RESULTS OF THE THIRD JOINT US-USSR BERING & CHUKCHI SEAS EXPEDITION (BERPAC) SUMMER 1988 UNITED STATES DEPARTMENT OF THE INTERIOR / Fish and Wndlife Service KJ <^ era CO 8 Ss^iJ3 • •• O M a IS"! L (V Woods ^-^^i Ju-^nographic \ - tieMco RESULTS OF THE THIRD JOINT US-USSR BERING & CHUKCHI SEAS EXPEDITION (BERPAC) '. r~ ; _D ; =0 : CD : O : r^ ; a I m ; D SUMMER 1988 ^wOQS VIC -u-^w >-■--• • T Li3P.Ar(Y , Results of the Third Joint US-USSR Bering & Chukchi Seas Expedition (BERPAC) Summer 1988 John F. Turner Director, US Fish and WildHfe Service, Washington, DC Yuriy A. Izrael Chairman, USSR State Committee for Hydrometeorology Moscow, USSR Harold J. O'Connor Project Leader, USA US Fish and Wildlife Service Patuxent Wildlife Research Center Laurel, Maryland Alia V. Tsyban Project Leader, USSR Institute of Global Climate and Ecology State Committee for Hydrometeorology Academy of Sciences Moscow, USSR Copies of this publication may be obtained from the Publications Unit, US Fish and Wildlife Service, 1849 C Street, NW. Mail Stop 130— ARLSQ. Washington, DC 20240. Suggested Citation: Nagel. P. A. (ed.) (1992). Results of the ThinlJoint US-USSR Bering & Chukchi Seas Expedition (BERPAC), Summer 1988. US Fish and Wildlife Service, Washington, DC. Disclaimer: The opinions and recommendations expressed in this report are those of the authors and do not necessarily reflect the views of the US Fish and Wildlife Service, nor does the mention of trade names constitute endorsement or recomiTiendation for use by the Federal Government. Foreword In the last few years, an ever-growing anthropogenic impact on different natural ecosystems and the adverse effects resulting from this impact have led humanity to reali/e the real threat of potential global ecological disasters and to give a high priority to environmental protection. Natural factors cause the bulk of nearly all man-made chemicals to eventually enter the World Ocean, which, owing to this, can be considered a tremendous reservoir/accumulator of contaminants. Elimination of these contaminants through natural processes of the ocean (i. e.. self-purification) occurs through a complex system of physical, chemical, and biological processes taking place in the ocean. However, conditions favorable for the existence of certain hydrobionts that were established over whole geological epochs are being disturbed by these anthropogenic impacts. For these reasons, it is obvious that while studying ocean pollution and its ecological consequences, it becomes necessary to have complex physical, chemical, and biological investigations, which calls for principally new, interdisciplinary approaches to the solution of this problem. The protection of the marine environment against the undesirable influence of anthropogenic factors are global problems common to all mankind. They can, and must, be solved by joint efforts of scientists from different countries. For this reason, and taking into consideration that the Bering and Chukchi Seas wash the US and USSR coasts (countries equally interested in the further fate of these unique regions of the World Ocean), it was considered appropriate that the efforts and knowledge of scientists of both countries be joined to study the state of the ecosystems of these seas. It is important to note that 1992 is the 20th anniversary of the US-USSR Agreement on "Cooperation in the Field of the Protection of the Environment" and the 1 5th anniversary of the beginning of joint US-USSR research within the framework of the special subproject "The Bering Sea." In 1977, 1984, and 1988, US-USSR integrated ecological expeditions aimed at investigations of Bering Sea ecosystems were carried out within the framework of the above agreement. These expeditions enabled scientists of both countries to add to the volume of knowledge of this poorly understood body of water. The following are the major research thrusts: a more detailed study of the oceanographic regime; accumulation of data on the spatial (horizontal and vertical) variability of nutrient concentrations; the study of the dynamics of arrival and elimination of the most important pollutants; acquisition of data on the structural and functional characteristics of planktonic and benthic communities; a more detailed study of the microbiological regime; and determination of the role of microorganisms in the biogeochemical cycles of elements in the destruction of organic pollutants. Long-term integrated investigations in the Bering Sea began on the first US-USSR expedition on board the R/V Volna in 1977. The scientific results of the expedition were presented in joint monographs published in the US (US Fish and Wildlife Service, 1982) and USSR (Izrael & Tsyban, 1 983 ). These investigations were further developed during the expedition canied out by Soviet scientists in 1981 on board the R/V Akademik Shirshov. New scientific data were obtained on the characteristics of the state of the Bering Sea ecosystem, the composition and physiological activity of bacterial populations, quantitative and qualitative composition of microzooplankton, and, investigated for the first time, the biogeochemical cycle of polyaromatic hydrocarbons (using the benzo(a)pyrene as the model compound). Scientific results of the expedition were published in the monograph Comprehensive Analysis of the Bering Seci Ecosystem (Izrael & Tsyban, 1987). The Second Joint US-USSR Bering Sea Expedition was carried out on board the RA' Akademik Korolev in 1984. During this expedition, a broad spectrum of questions were studied; they are considered in joint monographs published in the US (Roscigno, 1990) and the USSR (Izrael & Tsyban, 1990). The Third Joint US-USSR Bering & Chukchi Seas Expedition also took place on board the R/V Akademik Korolev in the summer of 1988. During the expedition, the Bering Sea (already investigated in 1981 and 1984), the Gulf of Anadyr, the Chirikov basin, and the southern Chukchi Sea were investigated (see Protocol of the Third Joint US-USSR Bering & Chukchi Seas Expedition . . . ). In the course of the third expedition, comprehensive studies of the state of Bering Sea ecosystems were continued and investigations in the Chukchi Sea were initiated. The present monograph contains scientific results obtained during the expedition and results which were obtained through //( situ laboratory experiments on samples collected during this expedition. The scope of problems elucidated in the monograph is wide: it includes the study of oceanographic aspects, hydrochemical conditions, variability of the spatial structure of planktonic biocenoses, microbial oxidation of organic pollutants, effect of toxic substances on the state of planktonic communities in conditions near to in situ, assessment of the elements of the ecosystem biotic balance, determination of the ratio between the processes of new formation and destruction of organic matter in the Bering Sea ecosystem, and determination of the elements of the biogeochemical cycles of organic pollutants in the Bering and Chukchi Seas. The investigations made it possible to conclude that, at present, the ecosystems of the Bering and Chukchi Seas are in a relatively favorable state. However, to maintain this state under conditions of ever-growing anthropogenic impacts from 111 both countries, a careful scientific approach is necessary to prevent exploitation of the natural resources of this unique area of the World Ocean. Scientific information obtained in the course of these joint ecological expeditions contributes to the development of such an approach. In conclusion, it should be noted that fundamental studies of northern polar marine ecosystems now have become even more important considering the newly emerging problems of global climate change. Ecological consequences of the predicted climate change on marine ecosystems may first manifest themselves in arctic areas of the ocean and affect fundamental natural phenomena, such as biogeochemical carbon cycling, sea level rise, production/destruction processes of organic matter, and others. Thus, these joint investigations of the role of arctic ecosystems in global climate formation processes, which were started by Soviet and American scientists, need continued extension and development. References Izrael, Yu. A. & Tsyban, A. V. (eds. ) ( 1983). Research on the Bering Sea Ecosystem. Gidrometeoizdat Publishers. Leningrad, 157 pp. (in Russian) Izrael. Yu. A. & Tsyban, A. V. (eds. ) ( 1987). Comprehensive Analysis of the Bering Sea Ecosystem. Gidrometeoizdat Publishers. Leningrad. 264 pp. (in Russian) Izrael, Yu. A. & Tsyban, A. V. (eds. ) ( 1990). Research on the Bering Sea Ecosystem. In Results of the Soviet-American E.xpeilition. The 37th Cruise of the Research Vessel Akademik Korolev. June-September, 1984. Gidrometeoizdat Publishers, Leningrad, 344 pp. (in Russian) Roscigno, P. F. (ed. ) ( 1990). Residts of the Second Jomi US- USSR Bering Sea E.xpedition. Summer 1984. US Fish and Wildlife Service Biological Report 90( 13). 347 pp. US Fish and Wildlife Service (1982). Joint USA-USSR Ecosystem Investigations of the Bering Sea. July-August 1977. Library of Congress #82-0845 13. Washington. D.C., 271 pp. IV Protocol of the Third Joint US-USSR Bering & Chukchi Seas Expedition on the RA^ Akademik Korolev In accordance with the memorandum of the 1 1th meeting of the US-USSR Joint Committee on the Environment Protection (Moscow, USSR, February 1988), the recommendation of the "Soviet-American Conference on the Ecology of the Bering Sea" ( Batumi, USSR, March 1988), and the plan of the joint bilateral activity of 02.07-2101 "Comprehensive Analysis ofMarine Ecosystems and Ecological Problems of the World Ocean", the Third Joint US-USSR Bering & Chukchi Seas Expedition was held on 26 July- 2 September 1 988 on board the Soviet research wtsi^eX Akademik Korolev. The delegation was headed by Prof. Alia V. Tsyban and Mr. Harold J. O'Connor (Project Leaders 02.07-2101 ). The Soviet delegates were represented by participants in the cruise from the USSR State Committee for Hydrometeorology and Control of Natural Environment; the Academy of Sciences from the USSR; and the Academies of Sciences from Ukraine, Belyorussia, and Estonia. A list of participants is given as Appendix A. The American delegates were represented by participants from the US Department of the Interior, Fish and Wildlife Service; University of Texas; Texas A&M University; University of Alaska; University of New England (Maine); University of Washington; University of South Carolina; Skidaway Institute of Oceanography; and Lamont-Doherty Geological Observatory. A list of participants is given as Appendix A. The principal objective of the Third Joint US-USSR Expedition was to characterize the contemporary condition of the fundamental oceanographic, hydrochemical (including pollution levels), and the hydrobiological parameters of marine ecosystems and to assess their assimilative capacity for marine pollution. This research was undertaken both on the polygons of long term investigations and in new areas of the Bering Sea (Gulf of Anadyr, Chirikov basin, and the Bering Strait ) and the southern portion of the Chukchi Sea. The main scientific tasks were 1. Biological, chemical . and physical fundamental data were collected to provide a comprehensive ecological and oceanographic profile of the Bering and Chukchi Seas. 2. Studies of the physiological and ecological characteristics of plankton organisms were conducted. 3. The ecological health of the Bering Sea was assessed. In accordance with protocols of the Joint American- Soviet meeting (Batumi, Mar. 1988), the research vessel Akademik Korolev. with the Soviet participants on board, arrived in Dutch Harbor. USA, on 24 July 1988. During a three-day port of call, the American specialists and their scientific equipment were taken on board. The Third US- USSR Expedition started on 27 July with the transit to the East Polygon. Complex ecological investigations in the Bering and Chukchi Seas were accomplished in four stages. In the first stage, work was started in the East Polygon (Stations 1-6) and was completed in the Gulf of Anadyr ( Stations 6-43). The next stage studied the areas of the southern Chukchi Sea (Stations 6—13) andincludedatransect of the Bering Strait. After a port of call to Nome, Alaska (USA, 17-18 August), investigations were continued in the Chirikov basin from the Bering Strait to St. Lawrence Island. The final stage of the expedition consisted of six stations (109-1 13)including the South Polygon. Complex ecological studies (see Frontispiece) were conducted in 113 stations of the transects and of three polygons (East, North, and South ). A map and station locations are found in the Frontispiece. The joint work and debarkation was completed on 2 September 1988 in Dutch Harbor. The entire duration of the Third US- USSR Expedition to the Bering and Chukchi Seas was 42 days. In accordance with specialties of the expedition's participants, working groups were organized (Appendix A). At these meetings, work schedules, joint studies, and model experiments were planned. During the expedition, several meetings of the Scientific Council Board were held. Examined were: /. ecological problems of monitoring studies of highly productive regions of the World Ocean; 2. the contemporary state of the knowledge of the Bering and Chukchi Seas' ecosystem; and 3. preliminary scientific results of the Third US-USSR Bering & Chukchi Seas Expedition. In the course of the meeting, scientific reports to the American and Soviet specialists were presented. During the Third Joint US-USSR Bering & Chukchi Seas Expedition, the following preliminary results were obtained: the research was undertaken in five different ecosystems in the Bering and Chukchi Seas. Two ecosystems were situated in the East and South Polygons and they have the characteristics of deep-water ecosystems. Three ecosystems were in shallow- water areas of the Bering Sea (Gulf of Anadyr, Bering Strait, Chirikov basin) and the Chukchi Sea (southern portion) and were typical shelf ecosystems. The structure of the water mass on the East Polygon consisted of the shelf s boundary and was influenced greatly by the Bering Current tlowing along the continental shelf-slope. Analysis of the distribution of temperature revealed the existence of two water layers. The minimum temperature was found at the depth of 150-250 m (boundary of the shelf- water of the Bering Current), and the maximum temperature was found at the depth of 400-500 m ( intermediate water of the Bering Sea). We must note that both the minimum ( 1 .6°C ) and the maximum (8.9°C) temperatures were approximately 0.3-0.5°C higher than the average long term data for the region. The distribution of nutrients ot the East Polygon was typical of such a shelf-slope region. In the surface layers the nutrients concentration was found to be low and their concentration increased slowly below 100 m. The microbiological community was characterized by variability ofwater mass in the East Polygon. The development of the heterotrophic, saprophytic microflora proved to be lower in total numbers in the deepwater stations 1 and 3 at the depth of 500 m (the indicator fonns were completely absent). There were upper and lower layers where the number of saprophytic bacteria varied from 0 cells/ml to 10' cells/ml. Preliminary data indicated that microbial community structure on the East Polygon did not change in comparison with the 1984 results. The highest quantity and biomass of neuston organisms was found on the East Polygon (in comparison with the other investigated areas). The average biomass was found to be four times higher than those results reported in 1984. Very interesting experiments were undertaken for the first time in the northern regions of the Bering (Gulf of Anadyr) and Chukchi Seas. The ecosystems of the northern areas of the sea are some of the most productive in the World Ocean. Results of primary production showed values more than 12 g C/m-d '. High concentrations of nutrients in the water masses are responsible for the high primary production. Significantly, the water mass is enriched with nutrients transported from the Gulf of Anadyr through the Chirikov basin and the Bering Strait to the southern area of the Chukchi Sea. This constant tlow fuels the increase of phytoplankton numbers and production occurs at the boundaries of these water masses. During the expedition, three local areas that had high phytoplankton production were discovered along the axis of the current. At these areas, the increase in biogenic sedimentation was also observed with the particulate matter settling from the euphotic zone containing more than 1.5% biogenic carbon. The lowest temperature (-1.6°C) was discovered in the Gulfof Anadyr. Such low temperatures have not been observed here during the last 20 years. In spite of the low temperatures, significant phytoplankton biomass was found in the Gulf of Anadyr. The highest values of chlorophyll « in the gulf reached 55 mg/nr\ The only values that were higher were those found in the Chukchi Sea. In the coastal area of the Gulf of Anadyr, a high quantity and biomass of microzooplankton and benthos were observed. Biomass of benthic organisms reached !.()()() g/nr in several investigated stations. The ecosystems in the Chirikov basin depend greatly on the Anadyr Current, which carries into the gulf different amounts of nutrients that are necessary for thte growth of phytoplankton. In turn, large amounts of nutrients were carried from the Chirikov basin through the Bering Strait to the Chukchi Sea. The southern area of the Chukchi Sea, bemg intluenced by Bering Sea waters, was rich in nutrients and unstudied until this time. Also, new practical knowledge of oceanographic features such as mass circulation, temperature, salinity distribution, and the general structural and functional characteristics of the ecitsystems was dclcrniined. During the expedition, we noticed that the function of the ecosystems of the Chukchi Sea was determined by at least two currents. High-salinity, nutrient-enriched, water masses are transported from south to north. They are carried by a flow that exits from the Gulf of Anadyr, crosses the Chirikov basin, flows through the Bering Strait, and ends in the Chukchi Sea. There is one more current, formed from the cold and relatively high salinity coastal Siberian waters, that is also enriched with nutrients. This current flows from northwest to southeast. These two flows of nutrients, discovered in the Chukchi Sea, determine the high biological productivity of this ecosystem. The merging of these two currents formed a wide area in the southeastern part of the sea. This area is characterized by the following: 1. concentrations of chlorophyll a reaches 77 mg/m' (a phytoplankton bloom was noticed at Station 45); 2. the average number of neuston organisms was 4,000 specimens/m-; 3. the number of infusoria of the Chukchi Sea was much larger than in the Bering Sea; 4. a maximum number of mesozooplankton was in the larvae of benthic organisms, which was dominated in the metazooplankton; and 5. high average biomass of benthic organisms — about 900 g/m- — was found, reaching 1,500 g/m- and even 2.000 g/m- at some individual stations. New species, which were not known before in the Chukchi Sea (testaceous moUusks, some echinodermata, and others) were found during the expedition. Many birds and mammals were also observed. From various investigations, the data indicate that the biological productivity is high in the Bering Sea and higher still in the Chukchi Sea. In spite of the fact that the investigated regions are far away from industrial areas, an array of anthropogenic organic contaminants ( polychlorinated biphenyls (PCB"s). hexachlorocyclohexane, chlordane. and DDT) were found in the surt'ace waters of these seas. The average measured concentration of hexachlorocyclohexane in the surface waters of both seas was more than 10 times the values of other anthropogenic contaminants (2.5 ng/1 isomer and 1.2 ng/1 isomer). Such levels of toxicants in the Bering and Chukchi Seas are potentially hazardous for the vulnerable arctic ecosystems. Analysis of the atmospheric samples produced similar results: concentrations of benzene hexachloride averaged 0.25 ng/m' and that for the isomer. 0. 12 ng/m'. The process of the degradation of the PCB's by natural microbial populations of the Bering and Chukchi Seas was studied. The preliminary results indicated that during the exposure (21 days) at temperate 6-10°C, the microorganisms oxidized up to 18% dichlorobiphenyl, up to 6% trichlorobiphenyl, 1% tetrachlorobiphenyl, and <1% penta/n-hexachlorobiphenyl (as compared to total amounts of these compounds compared in industrial mixtures of PCB ). It is important to note that the toxic compound 2, 3, 6, 2', 3', 6'-hexachlorobiphenyl was degraded by 50-70% by various bacterial populations for 2 1 days. Altogether these facts indicated thai a considerable part of chlorinated hydrocarbons may be retained and may accumulate in this arctic environment. This cau,ses serious concern as these pol I Litanls ha\ e known negative effects on biological processes. VI Experiments were conducted to study the photochemical decomposition of polyaromatic hydrocarbons (PAH's). For example, only a 3-hour exposure to sunlight of benzo(a)pyrene already showed a significant quantitative breakdown of this carcinogenic chemical. From the results of these studies, and from previous estimates of the accumulation of these compounds in the marine ecosystem, one needs to determine in detail the intensity of microbial destruction of pollutants; establish a "critical" concentration of individual pollutants that affect the ecological system; and study factors that affect important processes of the ecosystem. For example, the new formation of organic pollutants from the metabolic activity of microorganisms should be examined. During the period of the expedition, joint American- Soviet experiments were conducted. Preliminary results of these experiments allowed us to assess the range of "critical" concentrations of pollutants for microzooplankton in the Bering and Chukchi Seas. The range varied as follows: Benzo(a)pyrene 0.1-1 |ig/l Copper 2-8 ng/1 PCB 10-40 ng/1 Cadmium 20-40 [ig/l It is important to note that the established critical concentrations were l.OOOx higher that those found in natural seawater. With the results of the joint, multidisciplinary experiments, we have demonstrated that separate combinations of low concentration of nitrogen and phosphorus, which were typical for natural for natural water masses, not only do not stimulate but inhibit the growth of plankton communities. Most of the collected biological and chemical samples during the expedition need a prolonged series of studies in a laboratory with special equipment and instrumentation for final results to be obtained. However, even incomplete preliminary results obtained on board the ship, allowed us to assess the ecological structure and function in the Bering and Chukchi Seas as being intact, with both of these areas remaining as highly productive as any region in the World Ocean. Altogether, the distribution of chlorinated hydrocarbons (PCB, biphenyls, HCH) observed in the surface waters of these seas were probably transported by global atmospheric processes. At the end of the Joint Expedition on board the Akademik Korolev. there was an exchange of preliminary data. The future exchange of the joint analysis of data between American and Soviet scientists will occur in a series of three exchanges: /. 1 March 1988; 2. 1 June 1988; and 3. 1 October 1989. The two sides had agreed that the obtained data and results of the analyses belong to both sides. Any publications based on these materials should indicate that the results were generated during the Third Joint US-USSR Bering & Chukchi Seas Expedition. Both sides considered it useful to prepare and publish the joint manuscript containing the final analysis of the American-Soviet research of the 1 988 Expedition to the Bering and Chukchi Seas. American and Soviet participants expressed their interest in further development of joint research and consider it worthwhile to carry out further joint expeditions aimed to the fundamental studies of the ecological situation and the oceanographic regimes of the Bering and Chukchi Seas. Separate proposals for future joint research should be considered by the appropriate institutions in the respective countries. With this aim, the participants of the Third Joint US-USSR Bering & Chukchi Seas Expedition recommended that planning begin for the Fourth US-USSR Expedition to the Bering & Chukchi Seas, and the central Pacific Ocean in 1990. It is recommended also by the American-Soviet participants that a joint five-year program of ecological and oceanographic investigations for the Bering and Chukchi Seas will be jointly developed and published during 1989. Both sides note with satisfaction the friendly and constructive atmosphere of the expedition's work and the effectiveness of joint observations allowing for a variety of oceanographic and ecological studies. The American delegation would like to express their sincerest thanks and gratitude to the Captain and crew of the Akademik Korolev for their hospitality and cooperativeness. The American delegation thanks the Soviet delegation for providing an atmosphere of mutual respect, productive collaboration, and fruitful exchange of data. The associations established on this cruise will result in the exchange of data and information for many years to come. The Soviet participants of the expedition express their sincere gratitude and thanks to the American specialists for the fruitful and productive cooperation during the joint investigations of the Bering and Chukchi Seas. This protocol was written in English and Russian and was signed on board the research vessel Akademik Korolev, 2 September 1988. Both texts are equally authentic. For American side: The Leader of Project for the American Side Director, Patuxent Wildlife Research Center US Fish and Wildlife Service US Department of the Interior For Soviet side: Head of Expedition The Leader of the Project for the USSR Side Deputy Director of Laboratory for Environmental and Climate Monitoring Laboratory, Goskomgidromet and USSR Academy of Sciences Mr. H. J. O'Connor Professor A. V. Tsyban (This text is a reproduction of the protocol written on board the RA' Akademik Korolev in 1 988. The original was signed by both project leaders.) vii Acknowledgments We gratefully acknowledge and thank the many individuals without whose participation this monograph may not have been published with the same quality, accuracy, and clarity. We thank the US Fish and Wildlife Service and the USSR State Committee for Hydrometeorology for their continued support. Steven Kohl and Stephanie Miller. theCoordinatorand Associate Coordinator of US-USSR Programs, US Fish and Wildlife Service (Office of International Affairs), have provided invaluable assistance throughout every phase of this project. Their enthusiasm and energy given to this project, and the people involved with this project, are outstanding. Without each participant of the expedition and each author of research results, there would be no need for a monograph. There are far too many to name here; however, their names are listed with each subchapter and in Appendix A in this volume. It is their interest and excitement for the research presented here, and their spirit of cooperation so necessary for an international project, that provide the essence of the scientific accomplishments. We are indebted to each of the US and USSR chapter editors for their help and their patience with the seemingly endless questions and tasks assigned to them and, last but certainly not least, for their sense of humor, which is often the only saving grace in putting together a volume of this magnitude. Their names are listed alphabetically below: Sergei M. Chernyak Lawrence K. Coachman Gennady V. Panov Clifford P. Rice Boris V. Glebov Viktor V. Shigaev Jacqueline M. Grebmeier Gregory J. Smith Roger B. Hanson Alia V. Tsvban Cameron B. Kepler Yuriy L. Volodkovich Mikhael N. Korsak Terry E. Whitledge Alexander E. Lukin Stephen I. Zeeman C. Peter McRoy The "Production Team" at Patuxent Wildlife Research Center — Kinard Boone. Patricia A. Holt, Susan A. Liga, Robert E. Munro, Patricia A. Nagel, and John C. Sauer — deserves recognition for their dedication to meeting the challenge of producing a quality volume in time for it to be distributed to participants on the 1992 expedition. Harold J. O'Connor Alia V. Tsyban VIU Table of Contents Page Foreword iii Protocol of the Third Joint US-USSR Bering & Chukchi Seas Expedition on the RA' Akademik Korolev v Acivnowledgements viii Frontispiece xii Chapter 1 : GENERAL ECOLOGY 1 1 . 1 Program on Long-Term Ecological Investigations of the Bering Sea and Other Pacific Ocean Ecosystems (BERPAC Program) 3 1.2 Polar Marine Ecosystems and Climate 7 Chapter 1 References 13 Chapter!: OCEANOGRAPHY 15 2.1 Northern Bering-Chukchi Sea Ecosystem: The Physical Basis 17 2.2 Water Mass Modification from the Bering into the Chukchi Sea 27 Chapter 2 References 35 Chapter 3: HYDROCHEMISTRY 37 3.1 Biogenic Nutrient Content 39 Chapter 3 References 49 Chapter 4: MICROORGANISMS AND MICROBIOLOGICAL PROCESSES 51 4. 1 General Characteristics of the Bacterial Populations 53 4.1.1 Total Number. Biomass and Activity of Bacterioplankton 55 4. 1 .2 Thymidine Incorporation, Frequency of Dividing Cells and Growth Rates of Bacterioplankton 60 4. 1 .3 Bacterial Production and Destruction of Organic Matter 75 4.2 Heterotrophic Saprophytic Microflora 79 4.2.1 Distribution of Indicator Groups of Marine Heterotrophic Microorganisms 81 4.2.2 Taxonomic Composition of Heterotrophic Bacteria 87 4.3 Microbiological Transformation of Organic Matter 91 4.3.1 Transformation of Benzo(a)pyrene 93 4.3.2 Transformation of Polychlorinated Biphenyls by Marine Bacterioplankton 95 4.4 Biologic Characteristics of Marine Microorganisms 101 4.4. 1 Biological Features and Genotoxic Properties of Microorganisms 103 Chapter 4 References 1 1 1 Chapters: PLANKTON 117 5.1 Phytoplankton 119 5.1.1 Certain Characteristics of Phytoplankton 121 5.1.2 Phytoplankton Biomass Distribution in the Northern Bering Sea and Southern Chukchi Sea 123 5. 1 .3 Distributions of Algal Pigments in Near-surface Waters 127 5.1.4 Complex Hydrooptic Researches 135 5.2 Zooplankton 153 5.2.1 Ciliate Protozoa in Plankton 155 5.2.2 Characteristics of Zooplankton Communities 161 5.2.3 Some Characteristic Features of Epipelagic Necrozooplankton Distribution 172 5.2.4 Carbon Isotope Ratios in Zooplankton as Markers of Aging and Habitat Usage for the Bowhead Whale (Balaena Mysticetus) 177 5.2.5 Zooneuston 184 5.3 Icthyoplankton 193 5.3.1 Larval Fish Distribution 195 5.4 Modeling 199 5.4.1 Complex Ecological Evaluation of Planktonic Communities of the Pelagic Zone 201 Chapter 5 References 209 Chapter 6: PRIMARY PRODUCTION 213 6.1 Primary Production of Organic Matter 215 6.2 The Importance of Primary Production and CO, 2 1 8 6.3 Intensity of Biosedimentation Processes 224 6.4 Humic Acids 231 Chapter 6 References 237 Chapter 7: BENTHIC PROCESSES & BOTTOM FAUNA 241 7.1 Benthic Processes on the Shallow Continental Shelf 243 7.2 Characteristics of Benthic Biocenoses of the Chukchi and Bering Seas 251 Chapter 7 References 259 Chapter 8: BIOGEOCHEMIC AL CYCLES 263 8.1 Fate of Chlorinated Hydrocarbons 265 8.1.1 Long Range Transport of Atmospheric Organochlorine Pollutants and Air-Sea Exchange of Hexachlorocyclohexane 267 8. 1 .2 Migratory and Bioaccumulative Peculiarities in the Biogeochemical Cycling of Chlorinated Hydrocarbons 279 8.1.3 Organochlorine Contamination of Sediments, Fish, and Invertebrates 285 8.2 Fate of Petroleum Hydrocarbons 291 8.2.1 Distribution and Sources of Sedimentary Hydrocarbons 293 8.2.2 Distribution of PAH'S 301 8.2.3 Distribution of Benzo(a)pyrene and other Polycyclic Aromatic Hydrocarbons 308 8.3 Fate of Heavy Metals 315 8.3.1 Heavy Metals in Water and Sediment 317 8.3.2 Baseline Levels of Certain Trace Metals in Sediment and Biota 319 8.4 Distribution of Radionuclides 325 8.4.1 Investigation of Cesium-137 Distribution in Seawater 327 8.5 Distribution of Organic Matter 331 8.5.1 Characterization of Sediment Organic Matter 333 8.6 Abiotic Processes of Decomposition of Some Organic Contaminants 339 8.6.1 Solar Oxidation of Benzo(a)pyrene 341 8.6.2 Influence of Ultraviolet Radiation on the Fate of PCBs 343 Chapter 8 References 347 Chapter 9: ECOTOXICOLOGY 353 9.1 Effects of Pollutants on Plankton Communities 355 9. 1 . 1 Investigation of Negative Effects and Critical Concentrations of Some Toxic Substances on the Plankton Community 357 9. 1 .2 Effects of Hexachlorocyclohexane on Nitrogen Cycling in Natural Plankton Communities 364 9.2 Toxicity of Sediments to Test Organisms 371 9.2.1 Acute Toxicity Testing of Sediments 369 Chapter 9 References 377 Chapter 10: MARINE BIRDS 379 10.1 Water Masses and Seabird Distributions in the Southern Chukchi Sea 381 10.2 Associations Between Seabirds and Water Masses in the Northern Bering Sea 388 Chapter 10 References 397 Summary 399 General Conclusions 405 Appendix A 407 -68N -66N -64N ■-62N 180W Frontispiece. Sampling stations of the Third Joint US-USSR Bering-Chukchi Seas Expedition, Summer 1988. aboard the research vessel Akademic Korolev. Coordinates of the sampling stations on the Expedition. Station Latitude Longitude 1 57°53'67"N 174°49'85"W 2 57°49'97"N 175°5r83"W 3 57°94'50"N 175°07'50"W 4 58°50'83"N 174°50'33"W 5 58°50'00"N 1 75°50'{M)"W 6 59°50'00"N 179°30'00"W 7 60°47'43"N 177°87'03"W 8 60°93'53"N I76°94'62"W 9 61°33'52"N l76^1(r27"W Station Latitude Longitude 10 61°25'00"N 177^^76'00"W 11 61°58'33"N 178°65'00"W 12 61°88'17"N 179°42'00"W 13 62°18'33"N 179°85'00"E 14 62°83'68"N 179°5r08"W 15 62°55'00"N 178°50'00"W 16 62°34'I7"N 177°33'17"W 17 62°16'67"N I76°33'33"W 18 62°(K)'42"N 175°00'00"W Xll Coordinates of the sampling stations on the expedition - vouiinucd Station Latitude Longitude 19 62°4r67"N 174°00'00"W 20 62°3470"N 175°03'50"W 21 62°73'33"N 176°18'33"W 22 63°00'67"N 177°00'17"W 23 63°36'67"N 177°83'33"W 24 63°68'00"N 178°4735"W 25 64°00'00"N 179°33'33"W 26 65°00'00"N 178°66'67"W 27 64°74'00"N 177°77'50"W 28 64°25'00"N 177°50'00"W 29 63°83'00"N 176°97'33"W 30 64°17'33"N 175°96'83"W 31 64°33'33"N 175°00'00"W 32 64°00'00"N 175°00'00"W 33 63°50'00"N 175°00'00"W 34 63°16'67"N 174°00'00"W 35 63°00'00"N 173°00'00"W 36 63°42'83"N 172°16'67"W 37 63°66'17"N 172°82'67"W 38 63°91'67"N 173°58'33"W 39 64"=22'83"N 172°70'00"W 40 64°13'33"N 172°50'00"W 41 64°02'83"N 172°21'17"W 42 63°92'00"N 172°07'33"W 43 63°49'60"N 171°55'00"W 44 67°36'67"N 173°33'33"W 45 67°73'33"N 172°83'33"W 46 67°9r67"N 171°75'00"W 47 68°10'00"N 170°88'33"W 48 68°26'67"N 170°00'00"W 49 68°46'67"N 169°13'33"W 50 68°66'17"N 168°33'33"W 51 68°16'17"N 168°73'50"W 52 68°08'33"N 167°00'00"W 53 67°42'00"N 165°43'10"W 54 67°76'33"N 167°3r50"W 55 67°73'50"N 168°44'00"W 56 67°73'67"N 169°92'67"W 57 67°7r00"N 171°34'50"W 58 67^\50'00"N 172°20'00"W 59 67°15'33"N 172°00'00"W 60 67°26'17"N 170°82'67"W 61 67°33'33"N 169°75'00"W 62 67°33'33"N 168°7r67"W 63 67°34'17"N 167°73'33"W 64 67°29'67"N 166°7r00"W 65 67°33'33"N 165°00'00"W 66 66°92'50"N 165°9r83"W Station Latitude Longitude 67 66°93'33"N 166°83'33"W 68 66°9r67"N 167°83'33"W 69 66°90'75"N 168°9r08"W 70 66°9r67"N 169°9r67"W 71 66°9r67"N 171°00'00"W 72 66°55'00"N 170°16'67"W 73 66°55'00"N 169°3r67"W 74 66°55'00"N 168°60'00"W 75 66°55'00"N 167°23'33"W 76 65°93'33"N 169°58'33"W 77 65°9r67"N 169°36'67"W 78 65°85'00"N 169°2r67"W 79 65°70'33"N 168°67'50"W 80 65°66'67"N 168°50'00"W 81 65°63'33"N 168°35'00"W 82 65°63'83"N 168°33'33"W 83 65°67'13"N 168°49'83"W 84 65°7ri7"N 168°68'33"W 85 65°83'33"N 169°16'67"W 86 65°93'83"N 169°38'17"W 87 65°40'83"N 170°35'83"W 88 65°36'00"N 169°98'83"W 89 65°23'33"N 169°33'33"W 90 65°17'50"N 168°65'83"W 91 65°22'67"N 168°01'33"W 92 64°67'33"N I67°69'33"W 93 64°75'00"N I68°43'33"W 94 64°85'00"N I69°20'00"W 95 64°97'00"N 169°97'67"W 96 65°08'33"N 170°7333"W 97 64^^74'83"N 171°49'50"W 98 64°7r83"N 170°87'33"W 99 64°53'33"N 170°0r67"W 100 64°38'33"N 169°15'00"W 101 64°23'33"N 168°3170"W 102 64°08'67"N 167°38'83"W 103 63°66'67"N 168°33'33"W 104 63°84'50"N 169°20'50"W 105 64°03'33"N 170°08'50"W 106 64°22'33"N 170°98'17"W 107 64°38'33"N 171°65'00"W 108 54°49'33"N I76°49'17"E 109 54°53'83"N 175°47'50"E 110 53°95'00"N 176°01'17"E 111 53°52'67"N 175°53'17"E 112 53°I8'67"N 177°30'17"W 113 53°I3'67"N 177°19'50"W Chapter 1: GENERAL ECOLOGY Editors: ALLA V. TSYBAN & TERRY E. WHITLEDGE 1.1 Program on Long-term Ecological Investigations of the Bering Sea and Other Pacific Ocean Ecosystems (BERPAC Program) HAROLD J. O'CONNOR' . YURI Y A. IZRAEL^ , ALLA V. TSYBAN*. TERRY E. WHITLEDGE", C. PETER McROY , and LAWRENCE K. COACHMAN' 'US Fish and Wildlife Service, Patu.xeiU Wildlife Research Center. Laurel. Maiylaml. USA ' USSR State Committee for Hydrometeorology and Natural Environmental Control. Moscow, USSR ^Institute of Global Climate and Ecoloi^y. State Committee for Hydrometeorology and Academy of Sciences. Moscow. USSR "Marine Science Institute. University of Texas. Port Aransas. Texas, USA Institute of Marine Science. University of Alaska. Fairbanks. Alaska. USA 'School of Oceanography. University of Washington, Seattle, Washington, USA Introduction Deterioration of ecosystems on a large scale threatens many functional equilibria in the biosphere. This problem is particularly urgent for the World Ocean, which is the sink for many different pollutants that can produce significant ecological impacts. The ocean is able to assimilate a certain amount of anthropogenic compounds due to "self-purification" without visible deterioration of the ecosystem. However, continuous increase in the tlux of pollutants to the ocean creates the need for study of the resistance of marine ecosystems to anthropogenic impacts. Investigations of ecological consequences and elucidation of causal relationships between the impact levels and adverse biological effects are only poorly understood for the marine environment. The study of these interactions and responses is interdisciplinary in character and covers different fields of biology, ecology, chemistry, and physics of the sea. The dynamics of marine ecosystems, including biological and physical processes and biogeochcmical cycles, are closely related to changes in the climate of the Earth. The predicted global warming may have a pronounced effect on certain vital processes in the World Ocean, especially the resistance of its ecosystems to anthropogenic contamination. This is because the living ocean determines, to a great degree, the normal functions of the Earth's climatic system. Long-terni observations of physical, geochemical and hydrobiological processes are necessary for the assessment of ecological consequences of contamination in the ocean environment and isolation of local anthropogenic effects compared to the effect of climatic variability. The Bering Sea is located between the coasts of the Soviet Far East (USSR) and Alaska (USA ) and. naturally, an interest in the study of its ecosystems has been shown by Soviet and American scientists (Izrael & Tsyban, 1983a, 1977, 1990; Roscigno, 1990). In spite of comprehensive studies carried out in the Bering Sea in the last few years (Izrael et al. , 1 988b; Izrael & Tsyban, 1989, 1990; Coachman, 1990; Roscigno. 1990), a number of the oceanographic, hydrochemical. and biological parameters determining its ecosystem functions are as yet poorly known, when compared with, for instance, the Baltic, Mediterranean, and Black Seas. For example, the joint bilateral program of Bering/Chukchi investigations have been carried out for more than 13 years with the production of three monographs of cruise results. However, the as yet inadequate data on the characteristics and processes occurring in the ecosystems of the Bering Sea and North Pacific waters have led to the organization and implementation of an international program: Long-term Ecological Research of the Marine Ecosystems in the Arctic and Pacific Oceans (BERPAC Program). Goals, Objectives, and Scientific Basis of the BERPAC Program Goals The goal of the BERPAC Program is to examine the status of marine ecosystems of the Pacific Ocean, Bering Sea, and Chukchi Sea and to assess their role in determining global climate. BERPAC will study the dynamics ofthe.se ecosystems related to conditions ofglobal climate change and anthropogenic contamination. Objectives and Scientific Basis of the BERPAC Program Objectives of the BERPAC Program consist of the study of the biogeochcmical cycles of contaminants, related oceanographic processes, and food-web interactions in the North Pacific waters that flow through the Bering/Chukchi Seas, including study of the behavior of organic pollutants at the water/sediment interface since sediments are sources of the secondary pollution of ecosystems. Important topics of study are the control and the accumulation of pollutants in bottom deposits and the study of their migration within the sediments and their exchange with overlying waters . 1. Assessment of Ecological Consequences of Contamination Progressively severe changes in chemical contamination of the ocean biosphere are on the increase. Anthropogenic impacts influence not only the biotic component of the marine environment but different abiotic components as well. Such impacts lead to even more significant changes in the World Ocean and in the biosphere as a whole. Specific features of the Bering Sea and other ecosystems with "background" levels of contamination are such that they are especially vulnerable because of the continual input of small doses of pollution. This leads to a gradual accumulation of pollutants and may ultimately cause the degradation of the ecosystems. Therefore, ecological investigations and monitoring of the background regions of the ocean, especially in such highly bioproductive zones as the Bering Sea. are of great importance. In order to assess the ecological consequences of the pollution and isolate anthropogenic effects from the background of natural variability, it is necessary to make long- term observations of fundamental physical, chemical, and biological processes in selected areas of the above regions. These regions differ in their geographical location as well as in the subsystems of their ecosystems and are subjected to different anthropogenic impacts. 2. Study of the Processes Determining the Assimilative Capacity for Contaminants in Marine Ecosystems In the marine environment various physical, chemical, and biological processes occur through which contaminants can be eliminated from the ecosystem without serious disturbances of the biogeochemical cycles of the elements or changes in the biota. Diverse oceanological investigations carried out in the last few years have shown that the biotic component is important in the fluxes of pollutants. The ability of an ecosystem to protect itself against a foreign interference at the expense of many biological, physical, and chemical processes is its natural "immunity," and the measure of this immunity is its assimilative capacity. According to the contemporary interpretation (Izrael & Tsyban, 1983b, 1989; Izrael et ai. I988b,c), the assimilative capacity of a marine ecosystem is an integral function of its existing environmental status that reflects the ability of physical, chemical, and biological processes forelimination of pollutants and their impacts on the biota. When using the concept of assimilative capacity in practice, it is necessary to bear in mind that a marine ecosystem occupies a finite volume that may be isolated on the basis of the spatial distribution of organisms of various trophic levels, groups of ecologically similar species, and production/destruction processes, as well as physical and chemical characteristics. Hence, the assimilative capacity of each specific ecosystem also has a value that objectively characterizes existing properties of the marine environment. This value could be determined in practice on the basis of integrated investigations and monitoring of the marine environment carried out in accordance with existing methodological recommendations (Izrael & Tsyban, 1983b, 1985, 1987, 1989; Izrael et ai, 1988b). The use of this concept in the BERPAC studies will include investigations of the following basic problems: /. quantitative assessment of the balance of chemical elements in the ecosystem and possible changes in residence times due to disturbances; 2. assessment of adverse biological effects at the level of population and communities; and .?. determination of the critical concentrations at which contaminants adversely impact the marine organisms and communities. Thus, a conceptual model of the assimilative capacity, based on a better understanding of the laws of marine ecosystem functions, can serve as a theoretical basis for the development of forecasts of both the immediate and long-range consequences of anthropogenic and climatic impacts on the ocean ecosystems. 3. Study of the Elements of the Biogeochemical Carbon Cycle and its Role in Global Climatic Processes Global warming predicted in connection with the developing greenhouse effect depends directly upon the biogeochemical cycle of carbon — the most important process forming the Earth's climate. The basic elements of this cycle are carbon dioxide and other "greenhouse gases" exchanged within the ocean-atmosphere system, the function of the carbonate system, and the turnover of organic forms of carbon in the ocean. The most intensive uptake of atmospheric CO, occurs at high latitudes as a result of favorable thermal and hydrological conditions in the region (low sea surface temperature and permanent downwelling). These peculiarities explain the important role of the Bering Sea, a subarctic body of water having a large area, in the global cycle of carbon dioxide. The relationship between the rates and directions of CO, flow within the ocean-atmosphere system directly affects the functioning of the carbonate system. So, in the conditions where global warming is induced by an increase in the concentration of atmospheric CO,, a shift of the equilibrium between carbonate forms of carbon in seawater might occur, which will be accompanied by a decrease of pH and, consequently, elevation of the lysocline. Investigations of these processes, directly affecting the sedimentation of organic carbon and the vital functions of marine organisms, are only possible with direct determination of all components of the carbonate system (i.e., HCO„ CO,, H,CO„andCO,). To fully understand all of the characteristics of the oceanic portion of the global carbon cycle, it is necessary to study the processes of the circulation of its organic forms in the composition of dissolved and particulate matter and in the cells of living organisms (Zaitsev, 1970, 1980, 1983). The dynamic equilibrium of dissolved and particulate organic matter, living matter, and the content of organic carbon within water masses depends on the relations between production/destruction processes established in the ecosystem. In this connection, the predicted effects of global warming on the bioproductivity of the Bering Sea ecosystem will influence the organic carbon cycle. In order to study possible changes, long-term observations of the concentrations of all organic forms of carbon are necessary. Thus, to establish the carbon balance in the Bering Sea ecosystem, comprehensive long-tenn observations of all carbon constituents in the aquatic interface and the study of quantitative and qualitative composition of both the carbonate system and organic forms of carbon are required. 4. Investigation of the Physical Mechanisms Related to Climate Variations Existing global physical models of the ocean-atmosphere system do not make it possible to predict possible climate changes on a regional scale because of the extreme complexity of the modeled systems. Additional investigations of the physical development of regional models, in particular of a model for the Bering Sea, are an important need for long-term climate forecasting at the present time. This problem could be solved on the basis of long-term oceanological observations, in different regions of the Bering Sea, which are aimed at the acquisition of systematic information on the vertical distribution of temperature, heat content of the active layer and its variability with time, the structure and variability of ocean circulation, heat transfer by the basic sea currents, and heat and moisture tluxes across the sea surface. To develop the above models it is necessary to know the regularity of water mass formation in the deep basins of the Bering Sea. The following issues are not yet clear: North Pacific water must be involved in bottom water formation, but given the topographic isolation of Bowers and the central basins, how and where does this take place? Are sources the same for the different basins? What are the flushing rates (e.g., residence times)? There are three hypothetical mechanisms by which bottom water might possibly be formed: /. modification of surface (upper layer) water within the confines of the sea by cooling and brine enhancement through ice formation, creating water sufficiently dense to sink to the bottom; 2. subsurface mixings of North Pacific water with appropriate Bering Sea waters as it crosses the sills in the Aleutian-Komandorskiy island arc passages; and 3. direct advection of deep North Pacific water in through Kamchatka Strait and then sequentially through the gaps into the other basins. The BERPAC Program will investigate the mechanism of deep water formation, renewal rates, and flushing of the basins. Area of Investigations While selecting the study areas and location of stations in the Bering Sea, the diversity and contrast of ecological conditions in different regions of the sea were taken into account. In order to retlect a variety of ecological conditions in the Bering Sea more completely, it seems appropriate that integrated expeditions include work on polygons located in different areas of the sea (with the purpose of obtaining representative data on the structure and functions of the basic marine ecosystems) and work across transects (with the purpose of determining the space and time variations of the key ecological parameters). Investigations within the framework of BERPAC will be conducted on four polygons where investigations were carried out in 1981 (during the integratedecological expedition aboard the research vessel \Rjy]Akademik Shirshov), and in 1 984 and 1 988 ( during the second and third Soviet- American ecological expeditions aboard the RA' Akademik Korolev) (Izrael & Tsyban, 1987, 1990; Izrael e/ a/., 1988a; Roscigno, 1990). Deep stations will be repeated at four centered polygons in the four deep basins. The center station of each polygon will also be a location for a mooring containing sediment traps and current meters, funding permitting. Four other mooring locations will cover the entrance from the North Pacific (in the deep channel northwest of Komandorskiy Island), the main gaps in the ridges north of Attu, and a location on the east side of the central basin under the Bering Slope current. The mooring locations are also deep oceanographic stations, and 1 1 additional stations will provide continuity among the deep waters. In addition to polygons, observations are planned at stations along the transects located in areas that are not yet completely understood, such as the Gulf of Anadyr, the Chirikov basin, the Gulf of Alaska, the northern portion of the Pacific Ocean, and the deep-water central and southwestern areas of the sea. Larger scale studies in the Chukchi Sea and central Pacific ecosystems are also planned. The program for individual expeditions will be discussed specifically during joint symposia. Proposed Observations Complex observations during the ecological expeditions include meteorological (including aerological and geophysical studies), oceanographical, and ecological observations. Specifically, the following observations will be made: A. Meteorological observations will include routine observations of meteorological parameters, such as studies of direct solar radiation intensity and ultraviolet irradiation, cloud and cloud type studies, and collection of samples of atmospheric precipitation for chemical analyses. Aerological and geophysical observations will include temperature and wind sounding with the aid of radiosondes. Air samples will be collected for determination of sulfates and nitrogen oxides. Visual observations of oil and oil product contamination on the sea surface will be recorded. B. Oceanographic observations at designated sampling depths in the water column will include temperature, sahnity , nutrients, oxygen content, water color and transparency, biogenic elements, alkalinity, and petroleum hydrocarbons. Tracers for water mass types will include stable isotope content of seawater (oxygen, deuterium, tritium, freons, silica, and carbon 14). In addition, current velocity and direction will be determined, and sediment trap collections will be made. C. Ecological observations will include studies of the atmosphere, sea surface microlayer, water column, and bottom deposits in the environment. /. Atmosphere In rainfall, pH and the content of organic contaminants will be determined. In dust particles, the content of organic contaminants and metals will be determined. In the air at the sea surface, the content of "greenhouse" gases (CO,, nitrogen oxides), oxygen, and chlorinated hydrocarbons will be determined. 2. Sea Surface Microlaver. Water Column, and Bottom Deposits Water samples will be collected in the surface microlayer and at standard hy drological depths and at selected experimental depths (e.g.. themiocline. pycnoline. phyto- and zooplankton maxima, and sediment-water interface) (Zaitsev, 1980). a. In the surface microlayer. the following elements and parameters will be determined: - organic carbon ■ - contaminants (toxic metals, and aliphatic aromatic and chlorinated hydrocarbons), the state of neustonic communities; determination of the structural characteristics of bacterioplankton; total numbers, biomass of microorganisms, most probable numbers (MPN) of indicator groups of bacteria (e.g., paraffin- oxidizers, PCB-transforming and neurotrophic saprophyte groups), and indices of phyto- and zooneuston (numbers, biomass, species, size composition, species mass, and indicator forms), mutation (teratogenesis) of zooneuston organisms. h. In the water column, the following parameters will be determined: - water optical indices - contaminants (toxic metals, and aromatic, aliphatic, and chlorinated hydrocarbons) - the total concentrations of organic carbon and its composition - elements of the carbonate system (CO,, HCO„ CO,) - characteristics of bacterioplankton (total numbers, biomass, MPN, and distribution of indicator groups) and their biochemical and genetic capacities - structural characteristics of phyto-, microzoo-, and mesozooplankton (numbers, biomass, size, and species composition, species mass, and indicator forms) - functional characteristics of planktonic communities (heterotrophic CO. assimilation by bacteria, bacterial production, phytoplankton productivity) - biosedimentation rate of particulate matter. c. In the biota, the following parameters will be determined: - contaminants (toxic metals, and aromatic, chlorinated, and aliphatic hydrocarbons - organic carbon content, stable carbon, and nitrogen isotope content. (/. In bottom sediments, the following elements will be determined: - determinants (toxic metals, and aromatic, chlorinated, and aliphatic hydrocarbons - total organic carbon and nitrogen - stable carbon and nitrogen isotopes - structural characteristics of zoobenthos (numbers, biomass. species composition, and species mass) 3. Higher Trophic Levels During the expedition, zoological observations will be carried out: numbers, distribution, and migratory patterns of fish, birds, and marine mammals. 4. Model Experiments Model experiments will be performed under conditions similar to natural situations. During these experiments, the following parameters will be studied: - photochemical oxidation of organic contaminants - biodegradation potential of bacterioplankton with respect to organic contaminants (benzo( a )pyrene. PCB. etc.) - combined influence of contaminants on biological "targets'" and establishment of "critical" concentrations of the impact on plankton communities in the conditions of controlled ecosystems (Izrael, et ciL. 1988a) - sediment respiration and nutrient flux experiments. Connection with other International Programs The BERPAC Program has much in common with other international programs, but at the same time it has its own particular features mentioned earlier. Wide cooperation with other similar international projects is built within the framework of this program — in particular, in the preparation of joint marine expeditions. Wide data exchange is also planned. Schedule of Activities and Applications of Results Since 1977, successful joint investigations of Soviet and American scientists have been carried out in the Bering Sea within the framework of the specific theme of the bilateral cooperation "Bering Sea" (Project "Comprehensive Environmental Analysis"; Suhproject "Comprehensive Analysis of Marine Ecosystem State and Ecological Problems of the World Ocean"). Important stages of this cooperation were three joint ecological Soviet- American expeditions in the Bering Sea on the RA' V()//(«( Summer. 1977 }dndRJ\' Akadcmlk Korolev (Summer. 1984 and 1988). several symposia on the preparation of scientific programs, and analyses of the results of these expeditions, as well as three monographs describing the results of long-term Soviet-American investigations in the Bering Sea (Izrael & Tsyban. 1990; Roscigno. 1990). It is expected that these expeditions will be every four years and followed by international symposia and joint publications. Monographs on the results of future expeditions will be published. It is expected that seminars and symposia within the framework of the BERPAC Program will be conducted. Also included in the plans are special intercalibrations. a wide exchange of specialists, and joint experimental work. 1.2 Polar Marine Ecosystems and Climate YURIY A. IZRAEL* , ALLA V. TSYBAN' , TERRY E. WHITLEDGE", C. PETER McROY", and VIKTOR V. SHIGAEV* 'USSR State Committee for Hydrometeoroloiiy and Natural Environmental Control, Moscow, USSR institute of Global Climate and Ecology, State Committee for Hydrometeorohgy and Academy of Sciences, Moscow, USSR 'Marine Science Institute, University of Texas at Austin, Port Aransas, Texas, USA ' Institute of Marine Science, University of Alaska, Fairbanks, Alaska. USA Introduction The warming of the global climate predicted to have occurred by the middle of the next century will have a profound effect on the state of the World Ocean and, therefore, on the entire realm of relations between it and man. The magnitude and thrust of this effect may vary widely from one geographic zone to another. Possible physicochemical, ecological, or socioeconomic consequences will be detemiined by the specific characterofmarine ecosystems functioning, by regional factors, and by the roles played by particular regions in world and national economies. According to present predictions, the regions that will be most significantly impacted by global warming are those in higher latitudes (Roots, 1989), where most marked changes in the functioning of marine ecosystems may occur. This fact makes it a matter of urgency that we generalize the findings of ongoing environmental observations with a view to diagnosing the possible effects of global warming as early as is feasible. The assessment of these effects on circumpolar and polar marine ecosystems calls for the mobilization of a broad assortment of scientific methods and approaches. To this end, the present paper relies upon predictive assessments made available by global circulation models (GCM's) of the coupled ocean-atmosphere systems when applied to high-latitude regions; upon results obtained by modeling of the oceanic branch of carbon circulation in the marine environment; upon analyses of long-term environmental observations; and finally upon economic projections. The concluding section of the paper draws on these methods for an analysis of possible changes in the physicochemical parameters of the Bering Sea ecosystem that are expected to ensue as a result of the presumed warming of the world's climate. Effect on Physicochemical Processes Effect of Global Warming on the Temperature Regime and Water Circulation in the High-latitude Ocean Given all of its diverse ramifications, evaluation of the effect of global warming on the temperature regime and water circulation in the World Ocean is tantamount to the task of predicting possible changes in all fundamental natural processes as a result of new climatic conditions. Since changes in the composition of the atmosphere and its circulation affect processes occurring in the ocean and vice versa, dealing with the this problem requires consideration of the operation of the ocean-atmosphere system in conditions of a developing "greenhouse effect." In this connection, one of the most promising methods of investigating the sensitivity of the climatic system to the mix of gases constituting the atmosphere involves performing numerical experiments using models of global circulation in the unitary ocean-atmosphere system (Manabe&Stouffer, 1980;Schlesinger, 1986). Results obtained from such calculations make it possible to predict changes in temperature over the entire air column and in the surface layer of the ocean as a function of a given atmospheric composition and more especially as a function of CO, levels in the atmosphere. Of the numerous GCM ' s presently available for describing the behavior of the ocean-atmosphere system, we would suggest that the models that are most carefully developed and take into account the maximum number of factors affecting circulation processes are those developed by Oregon State University (Ghan, 1982; Schlesinger & Mitchell, 1987); Goddard Institute for Space Studies (Hansen et al., 1983, 1988); and by the NOAA Fluid Dynamics Geophysical Laboratory at Princeton (Manabe & Wetherald, 1980, 1987). Considerable quantitative differences notwithstanding, results obtained from numerical experiments run on the basis of the above models have shown close qualitative agreement of predicted trends in the behavior of the ocean-atmosphere thermal balance in high-latitude regions in the event of a doubling of the CO, content of the atmosphere. A constant problem with such models is the extremely widespread ice cover and the very weak thermohaline circulation in the northern part of the North Atlantic and Arctic Oceans (Bryan et al., 1988). According to calculations, the temperature of the lower layers of the atmosphere may be expected to rise by from 1 .3° to 4.2°C, with greater warming occurring over land than over water; the surface waters of the ocean would become 0.2° to 2.5°C warmer. Analysis of the seasonal dynamics of the temperature field with all three models indicate that maximum warming would occur in the Arctic and Antarctic regions during the winter period. The particular importance of the latter factor for the system of water circulation in the World Ocean should be noted. Thus, significant warming in the polar latitudes would be associated with a decrease in the temperature gradient between the equator and the poles and, as a consequence, with a decrease in the intensity of winds and oceanic currents (Mitchell, 1988). This in turn could lead to a shrinkage of oceanic upwelling areas and weakened upwelling. In addition to its effect on the circulation of World Ocean waters, warming in the Arctic and Antarctic region would have a marked impact on the state of the Earth' s cryosphere (glaciers, shelf and marine ice). Such changes would in turn affect the functioning of the climatic system. First, the ice that covers 1 1 % of the World Ocean's surface area to a large extent determines heat transfer between ocean water masses and the energy balance at the ocean-atmosphere interface. These factors influence the intensity of oceanic convection, which in turn establishes the time scale of processes that extend to great depths (e.g., CO, circulation). In addition, exposed ocean waters absorb considerably more solar radiation than do ice-covered waters (Walsh, 1983). Hence, changes in the extent of ocean ice cover would inevitably affect atmospheric circulation and temperature. Second, even minor changes in the Earth's cryosphere would lead to a significant change in global sea level as compared with current values. The rise in air temperature expected to occur in the Arctic would have considerable consequences for the extent of marine ice cover. Thus, sunmiers could bring about the complete melting of the ice cover around Svalbard, along the north coast of Siberia, and along the Arctic coast of Canada. Nevertheless, in our view the global warming predicted by the middle of the 2 1st century will not lead to a majordiminutionof the ice mass of the Antarctic and Greenland ice shields. Indeed, recent studies in the Northern Hemisphere have shown that the extent of ice cover over the past decade has increased despite a small rise in mean annual temperature (Bryan et uL, 1988). On the otherhand, the warming by 4° to 5°C that is expected (Mitchell, 1988) may lead to an acceleration of the flow of continental ice sliding into the ocean and, therefore, to some decrease in ice- cover thickness in the western Antarctic (Bud'ko & Izrael, 1987). It may be noted in summary that global warming would very likely entail displacement of surface isotherms toward the poles, changes in the functioning of upwelling areas, and some shrinkage of ice cover in the Arctic. Melting of sea ice in the Arctic may produce a freshening of waters in the northern Atlantic with consequential changes in the formation of ocean- bottom waters. This process may affect heat flow in a northerly direction, which might ultimately result in a shift in global oceanic circulation (Bi7an el <;/., 1988). Changes in the Carbon Cycle The doubling of the carbon dioxide content of the atmosphere predicted for the year 2050 may well disrupt the global carbon cycle and therefore involve severe consequences for the formation of the Earth's climate. Assessment of these consequences requires profound insight into the cause-and- effect relationships that constrained the natural variability of CO. content in past geologic ages. It should be noted that the elevated solubility of carbonates occasioned by the increased salinity of seawater resulting from increased CO, levels produces increased alkalinity and therefore augments the ocean's CO,-hoIding capacity (Boyle, 1988). Furthermore, CO, absorption in upwelling areas occurs largely through the photosynthctic activity of phytoplankton, whereas in the higher latitudes considerable amounts of atmospheric CO, are extracted by oceanic masses in the process of deep- water formation, particularly in places where the deep waters in question rise to the surface (Roots, 1989). In addition, increased carbonate solubility (as a consequence of the acidulation of the surface layer by increased amounts of dissolved CO,) can raise the alkalinity of seawater and hence enhance the ocean's ability to absorb CO, (Boyle, 1988). Possible increases in the amount of organic matter deposited in bottom sediments due to augmented entry into the marine environment of biogenic elements due to sea level rise can also be regarded as a probable mechanism of removal of human- generated CO, from the atmosphere (Siegenthaler, 1989). It is therefore evident that rises in the carbon dioxide content of the atmosphere may result in a disruption of the global carbon cycle. The scale and thrust of possible changes would be determined largely by the particularities of upwelling ecosystem functioning under global warming conditions. Changes in Biogenic Elements Increased releases into the atmosphere of gases and aerosols containing nitrogen, phosphorus, and sulfur compounds as a result of human activities in highly industrialized countries such as those of the North Atlantic seaboard are increasing the amount of these substances entering the ocean (Oppenheimer, 1989). This process is particularly significant in the case of nitrogen and sulfur, whose entry into the photic zone of the ocean through the atmosphere may be compared with its delivery by diffusion convection (Duce, 1986). Rises of nitrogen and sulfur levels of regional scale, especially in impacted ocean areas, may be accompanied by rises in the bioproductivity of the affected ecosystems. Such phenomena have already been reported for the coastal marine areas of the North Sea (Lancelot et al., 1987). Sea level rises accompanied by flooding and soil erosion would result in considerably augmented influx of N, P, and S into coastal areas, which might well produce intensified eutrophication processes in the ecosystems thus impacted. One consequence of this may be an acceleration of the biogeochemical cycles of all biogenic elements (Oppenheimer, 1 989). This would depend on regional circumstances, however. In the Beaufort Sea, for example, the erosion-susceptible peat might become an important source of organic carbon for the food chain in adjacent coastal waters. On the other hand, most continental high-latitude regions can expect increased precipitation, which would tend to increase biogenic-element input into the nearby ocean. Changes in Polliiltnit Cycles Being associated with the intensification of microbial degradation processes, the rise in marine surface-water temperature currently predicted for the higher latitudes could result in the accelerated hiodegradation of globally occurring pollutants (chlorinated and petrolic hydrocarbons, phenols, etc.), which would, in turn, promote the decomposition of such compounds down to their low-molecular-weight components and their flushing from the photic layer of the ocean (Tanabe, mSSJzraelera/., 1990). Ontheotherhand.highertemperatures imply reduced absorption of organic pollutants on suspended matter (Pierce et al., 1974), which would have the effect of diminishing the amounts of pollutants deposited in sea-bottom sediments. The increased fluxes of U V-B radiation being predicted in connection with the depletion of stratospheric ozone layer would intensify photochemical processes, especially at that ocean-atmosphere interface (Zika, 1989). This would enhance the photodegradation of both chlorinated and petrolic hydrocarbons, possibly reducing this type of pollution of marine environments (Doskey & Andren, 1987). It should be noted, however, that apart from this positive effect of promoting the removal of organic pollutants from seawater, prolonged UV-B irradiation may also prove very detrimental to any number of marine organisms inhabiting the surface layer of the ocean (US EPA, 1987). It may be expected that rises in the concentration of atmospheric CO, would produce a certain acidulation of surface waters ( Wilson & Mitchell, 1987). Even though this would not affect the behavior of hydrophobic organic pollutants, the consequences might prove very tangible from the standpoint of ionogenic compounds. Thus, lower pH values would tend to increase the permeability of cell membranes with respect to such compounds, and hence to the accumulation of the latter in marine organisms (Landner, 1989). In addition, higher acidity may reduce the stability of heavy metals hound by compounds ofhumic origin (Mantoura& Riley, 1975; Paxeus, 1985). This process could in turn exacerbate the toxic effects of heavy metals on marine biota (Sunda & Lewis, 1 978; Sedlacek et ai, 1983). Effects on Environmental Processes The predicted changes in the physicochemical parameters of the marine environment as a result of global warming would no doubt have considerable impact on the intensity and balance of the fundamental environmental processes occurring in marine ecosystems, as well as on the condition of biological resources both in coastal waters and in open sea and open ocean areas. Changes in the Conditions of Habitation of Marine Organisms As a rule, marine organisms possess considerable environmental (genetic, behavioral, etc.) flexibility, which enables them to adapt to continuously varying environmental conditions. This adaptability of marine organisms accounts for the relative stability of zoogeographic zonation with respect to climatic fluctuations (Odum, 1986). It is to be expected that global warming would be accompanied by directed ecological succession that would enable communities to adapt to a warmer climate; some high-latitude communities may acquire the characteristics of boreal communities, while temperate zone communities might become more like their subtropical counterparts. The processes described above could have serious consequences for the formation and distribution of all marine biological communities, including those of commercially important fish species. The effect of warming would be especially pronounced in subpolar-front regions ( Roots, 1 989), where increases of even a few tenths of a degree in deep water temperature can lead to a noticeable redistribution of both pelagic and benthic communities. On the other hand, comparable temperature rises in the tropical latitudes would have no significant effect on the functioning of marine organisms. It should be noted that temperature is not the only parameter that would be decisive for the state of marine life communities in the higher latitudes under global warming conditions. Another set of factors of considerable importance would be associated with possible changes in oceanic and atmospheric circulation (Bakun, 1990), which is an important influence on the distribution and density of marine populations. Changes occurring in the open ocean and in coastal areas might be associated with changes in species diversity. This effect would probably be less in evidence in the open ocean than in estuaries and tidal zones. Polar marine ecosystems in open areas would move more readily into new geographic zones, while coastal ecosystems would be more rigidly restricted by the physical characteristics of the relevant shoreline. This leads to the general conclusion that what one may expect in conditions of global warming that can entail considerable changes in the living condition of marine biota is a redistribution of marine life communities with the inevitable consequences for the fishing industry worldwide. Changes in Production-Degradation Processes and Biogenic Sedimentation In contrast to tropical and temperate regions where productivity is determined largely by biogenic-element levels alone, the chief limiting factors in circumpolar and polar areas are light and temperature. In this connection, the predicted warming of surface waters would lengthen the phytoplankton vegetation season, and therefore increase the productivity of such areas. On the other hand, temperature rises would be accompanied by accelerated microbial decomposition of organic matter. The most pronounced intensification of decomposition processes (by a factor from 1.1 to 1.3) might be expected to occur in the higher latitudes and more particularly in the shelf waters and surficial water masses of the boreal zone (Odum, 1986;Izrael&Tsyban, 1989). The rates of degradation processes in surface waters in the lower latitudes is determined by the influx of organic matter from the Arctic and Antarctic as intermediate and deep waters arrive by meridional transfer. This is why the effect of temperature on the rates of degradation processes in the equatorial and tropical regions is negligible. The changes in production-degradation parameters would have aconsiderable effect on the course biosedimentation proces.ses. According to one model ( Suess. 1 980), the magnitude and velocity of the biosedimentary flux is increasing in direct proportion to rising productivity. Given this circumstance, climate warming could increa.se biosedimentary fluxes in coastal upwelling areas where a significant rise in productivity is expected to occur (Bakun, 1990). The same could happen in coastal land areas that would be flooded as result of sea level rise. One the other hand, the acceleration of biodegradation processes in the higher latitudes would preclude any marked increases in biosedimentary fluxes. In addition to rising temperature, another factor that would affect the formation of new organic matter in the ocean would be the further intensification of ocean pollution due to human activities. According to present estimates, pollutant levels in the euphotic layer of the ocean by the middle of the next century can be expected to rise from 25% to 30% above current values (Izrael & Tsyban, 1989). Moreover, warming of water masses coupled with the acceleration of chemical reaction could increase the toxicity of pollutants for marine biota. This would necessarily have an adverse effect on the productivity of polar oceanic ecosystems (Patin, 1979; Tsyban et al.. 1985). It should be noted in conclusion that primary production values for a region do not constitute an adequate yardstick for assessing commercial fish resources. What is more important, as far as the fishing industry is concerned, would be the shifting of the most productive zones of the World Ocean, and especially of upwelling areas, as this would be fraught with serious repercussions in terms of the distribution of commercial fish stocks and fish resources replenishment. The Role of Ice in Sustaining Marine Polar Ecosystems Ice plays an important role in the development and sustenance of marine polar ecosystems for the following reasons: /. it is extremely important to the growth of the marine algae that are the primary food source in marine ecosystems; 2. it creates conditions conducive to primary-production synthesis at the ice-water interface, allowing plants to bloom, thus maintaining the abundance and species diversity of biological communities; i. it is extremely important to the vital activity of the organisms that ensure energy transfer from the primary- production level ( algae and phytoplankton ) up to higher trophic levels (fishes, marine birds and mammals); and 4. the latter factor in turn operates to maintain existent numbers of marine communities. One of the possible consequences of global warming might be the shrinkage and diminished stability of marine ice, which would directly affect the productivity of polar ecosystems. For example, the absence of ice over the continental shelf of the Arctic Ocean would produce a sharp rise in the productivity of this region, provided sufficient biogenic elements are available. Polar mammals need ice to obtain their food and to reproduce. For example, the extent of the polar bear's habitat is determined by the maximum seasonal surface area of marine, ice in a given year. This means that the disappearance of ice would threaten the very survival of the polar bear and of certain marine seals. Similarly, a reduction of ice cover would reduce food supplies for penguins and walruses and increase their vulnerability to natural predators and human hunters and poachers. Should the ice cover shrink, animals such as the sea otter would have to migrate to new territories. Furthermore, it remains unclear how the contraction of ice cover would affect the migration routes of animal (such as whales) that follow the ice front. Changes in water temperature and wind patterns as a result of global warming would almost certainly affect the distribution and size of the polynyas (unfrozen patches of water surrounded by ice ), which are so vital to the maintenance of polar ecosystems. In addition, changes in the extent and persistence of marine ice, combined with changes in the characteristics of currents such as the circumpolar current in the southern latitudes, could influence the distribution, biomass, and volume of available krill. Krill is an important link in the food chain of Antarctic Ocean fauna and is also of great importance for commercial fisheries. A proper understanding of the way in which the productivity of the Antarctic Ocean would change under new climatic conditions is essential in assessing the consequences of global warming for the World Ocean environment. Effects on Fish Stocks oi Climate change is one of the paramount factors that determine the fish reserves of the World Ocean, even though the sensitivity to this factor of particular stocks varies considerably from population to population and from region to region. Each population of a given species community is fitted to a particular hydrody namic structure with definite temporal and spatial characteristics. Given this fact, changes in ocean circulation could lead to the disappearance of certain populations or to the appearance of new ones. Most seriously affected would be the populations localized in habitat boundary waters (Troadec. 1989). One of the promising avenues for predicting the possible consequences of climate warming on the status offish fauna is the method of historical analogies. This method involves isolating salient features in the distribution and biomass offish stocks over a number of past intervals such that each interval is associated with specific climatic, and therefore environmental, characteristics, the purpose being to draw further analogies. The application of this method for describing the state of fish resources over the present century has made it possible to discern certain essential features. The warming that occurred in the first half of the 20th century was accompanied by the penetration of northern fish species into subarctic and arctic seas, something that was observed both in the North Pacific and the North Atlantic. Thus, a favorable change in environmental conditions as a result of warming can generate new commercial fish stocks. Moreover, the warming of the 1940"s and 1950"s showed that warming of the marine environment can have quite different consequences even for a single fish species, depending on specific features of habitat. For example, this period saw the most sizeable generations of Atlantic-Scandinavian herring, while the number of North Sea herring plummeted. Recent studies in the North Atlantic have brought to light a direct link between climatic variation on the one hand and the distribution and replenishment of fish resources on the other. Particularly noteworthy in this connection is the so-called "1970's anomaly" (Jenkins & Ephraums, 1990), remarkable for the concurrent effects it involved for several commercial stocks. Originating off the coast of eastern Greenland in the 10 lale I96()"s, it went on to skirt Greenland and Labrador in the direction of the North Atlantic current, reaching the Barents Sea in 1979-80 (Dickson ('?«/., 1984). In the late I980"s.this anomaly led to extremely low prevailing temperatures in the waters off northern Iceland, which was probably the cause for the drop in numbers of Atlantic-Scandinavian herring. The above changes in fish resources were brought about by relatively short-term tluctuations in the temperature of the environment. Proceeding on the assumption that global wanning would entail a long-term upward creep t)f temperatures, this factor may be expected to have even more profound effects on the fish resources of the ocean. A rise in the mean temperature of polar and subpolar waters of the World Ocean of just l°C could have a substantial influence on the distribution, growth, and replenishment offish populations. Commercially valuable fish stocks may acquire new spawning grounds, which would entail considerable changes in their distribution patterns. The strong homing instincts of salmonids in the Northern Hemisphere would probably render changes in the geographic distribution of these species to be fairly difficult. On the other hand, salmonid populations may suffer considerable attrition should geographic shifts of habitat become an absolute necessity for thein. A more complete assessment of the effects of global warming on the state of fish resources in the high latitudes of the World Ocean requires allowance not only for temperature rises, but also for increased hard ultraviolet radiation fluxes. The latter factor would impact first and foremost upon those fishes whose early developmental stages live either in neuston communities or in coastal ecosystems. It must be borne in mind that notwithstanding the relative opaqueness of seawater to ultraviolet radiation, the roe and fry floating and swimming near the surface, together with the accompanying phyto- and zooplanklon, corals, and algae of tidal /ones, would be subjected to prolonged and intense irradiation, which may well increase the mortality of young fish and adversely affect the gene pool of the marine organisms in question. Regional Aspects of the Problem (Using the Bering Sea as an Example) Taking into account all of the foregoing, we would draw particular attention to the extensive body of information concerning the functioning of the Bering Sea ecosystem built up in the course of long-term joint US-USSR studies (the project entitled Comprehensive Analysis of the Bering Sea Ecosystem, under the "Bering Sea" Program). According to predictions based on the use of GCM's, the effect of global warming on the Bering Sea region could take the fonri of a displacement of surface water isotherms toward the North Pole (warming by 0.5°C over a single decade would be accompanied by a shift in isotherms of over 30 km | Hansen et ai, 19881 ). Temperature rises could lead to earlier vernal blooming of phytoplanktt)n and to a lengthening of the entire blooming season. By present estiinates, primary production in the Bering Sea averages 0.6.3 g C/m7day, attaining 7 g C/ni7day in some places (McRoy&Goering, 1976; Izraelefa/., 1986;Whitledge etai. 1988). The predicted advent ofconditions more conducive to phytoplankton vegetation suggests increases of primary production up to 0.75-0.90 g C/m'/day. Starting from a current rate of degradation of organic matter in the Bering Sea that averages 0.3 g C/mVyear (Izrael et ai. 1986; Whitledge et ai, 1988), global warming might bring this value up to 0.35-0.50 g C/mVyear. The expected acceleration of microbiological and photochemical processes would be accompanied by more rapid decomposition of organic pollutants and, as a consequence, by a reduction of levels of pollution of the given ecosystems by human activities (Izrael et ai. 1990). An intensiflcation of production-degradation processes could also result in the acceleration of biosedimentation processes, especially in coastal areas. According the latest experimental assessments based on determinations of organic- matter biosedimentation rates (Izrael et al., 1986), 1.6 X 10' tons of C settle to the bottom of the Bering Sea annually. On condition that the balanced character of the biogeochemical carbon cycle is maintained, this value can be taken as the lower limit for the influx of atmospheric carbon into the waters of the Bering. It is relevant in the connection to mention that the total contribution of carbon to the World Ocean is 53 x 10'* tons/year (Odum, 1986). These figures confirm the significance of subarctic ecosystems in the overall context of the global carbon cycle and point up their major role in shaping the Earth's climate. One of the inost significant consequences of global warming may be the displacement of the subarctic front, which would entail radical changes in the environment of pelagic and benthic communities, including many valuable fish species. Since the Bering Sea is a fishing area of enormous importance to a number of countries that together catch 3 x lO*" tons of fish annually (Wilimovsky, 1974), it is imperative to foresee possible detrimental consequences of global warming in this region as they impact upon the distribution and replenishment of many valuable species offish, birds, and mammals. Elaboration of prognoses of the state of living resources in the Bering Sea area in conditions of global warming would greatly facilitate the development of an effective system of adaptive responses for this region. The long-term studies in the Bering and Chukchi Sea conducted over the past decade will continue and will in future encompass the issues discussed in the present paper within the context of BERPAC. Efforts under BERPAC are part of the USSR's MONOK program: The Integrated Ecological Ocean. 11 12 Chapter 1 References Bakun, A. (1990). Global climate change and intensification of coastal ocean upwelling. Scieme lAl . 198-201. Boyle, E. A. (1988). Vertical oceanic nutrient fractionation and glacial/interglacial CO, cycles. Nature 331, 55-56. Biid'ko, M. 1. & Izrael, Yu. A. (eds. ) ( 1987). Anthropogenic Change of Climate. Gidrometoizdat Publishers. Leningrad. 378 pp. Coachman. L. K. (1990). Bering Sea ecosystem: Basic characteristics and prospects for long-term research. In Research on the Bering Sea Ecosystem. Results of the Second Soviet - American E.xpedition. The 37th Cruise of the Research Vessel Akademik Korolev, June - September 1984. Gidrometeoizdat Publishers, Leningrad, 2. (in Russian ) Dickson C, Meincke. M.. Malmberg. R. & Lee. G. ( 1 984). The great salinity anomaly in the northern North Atlantic. Prog. Oceanogr. 20, 2. Doskey, P. V. & Andren. A. W. (1987). Modeling the flux of atmospheric polychlorinated biphenyls across the air-water interface. Environ. Sci. Technol. 15, 705-71 1. Duce, R. A. (1986). The impact of atmospheric nitrogen, phosphorus, and iron species on marine biological productivity. The role of air-sea exchange in geochemical cycling (P. Buat Menerd. ed. ). pp. 497-529. Ghan. S. J. ( 1982). A documentation of the OSU two-level atmospheric GCM model. CRl Report 35. Oregon State University. 395 pp. Hansen, J., Fung, 1., Lacis, A., Rind, D.. Lebedeff, S., Ruedy. R. & Stone, D. (1988). Global climate change as a forecast by Goddard Institute for Space Studies three-dimensional model. / Geophys. Res. 93, 9341-9364. Hansen, J., Russel, G., Rind, D., Stone, D., Lacis, A., Lebedeff, S., Ruedly, R. & Travis, L. (1983). Efficient three- dimensional global models for climate studies: Models 1 and II. Mon. Wea. Rev. Ill, 609-622. Izrael. Yu. A. & Tsyban. A. V. (1983b). Research on the assimilative capacity of the World Ocean. Reports of the USSR Academy of Sciences 272(3). 702-705 . (in Russian) Izrael. Yu. A. & Tsyban. A. V. (eds. ) ( 1983a). Research on the Bering Sea Ecosystem. Gidrometeoizdat Publishers, Leningrad, 157 pp. (in Russian) Izrael, Yu. A. & Tsyban, A. V. (1985). The ecology and problems of global ocean monitoring. In Comprehensive Global Ocean Monitoring 1, 19-48. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael, Yu. A. & Tsyban, A. V. (eds. ) ( 1987). Comprehensive Analysis of the Bering Sea Ecosystem. Gidrometeoizdat Publishers, Leningrad, 264 pp. (in Russian) Izrael, Yu. A. & Tsyban. A. V. ( 1989). Anthropogenic Ecology of the Ocean. Gidrometeoizdat, Leningrad, 528 pp. (in Russian) Izrael, Yu. A. & Tsyban, A. V. (eds. ) ( 1990). Research on the Bering Sea Ecosystem. In Results of the Soviet - American E.xpedition. The 37th Crui.se of the Research Vessel Akademik Korolev. June-September. 1984. Gidrometeoizdat Publishers, Leningrad, 344 pp. (in Russian) Izrael. Yu. A.. Tsyban. A. V.. Panov. G. V.. Korsak. M. N., Kudryatsev, V. M.. Volodkovich, Yu. L. & Chemyak, S. M. (1986). Comprehensiveanalysisof the Bering Seaecosystem. Monitoring and managing environmental impact: American and Soviet perspectives (G. E. Schweitzer & A. S. Phillips, eds. ). National Academy Press, pp. 58-88. Izrael. Yu. A., Tsyban, A. V.. Panov. G. V., Korsak, M. N. et al. (1988a). Comprehensive analysis of the Bering Sea ecosystem. In Comprehensive Analysis of the Environment. Proceedings from the Fifth USSR-US Symposium. Gidrometeoizdat Publishers, Leningrad, 528 pp. (in Russian) Izrael, Yu. A., Tsyban, A. V., Ventzel, M. V. & Shigaev, V. V. ( 1988b). Generalized model of the assimilative capacity of a marine ecosystem. Reports of the USSR Academy of Sciences 380(2) . (in Russian) Izrael, Yu. A., Tsyban, A. V., Ventzel, M. V. & Shigaev, V. V. ( 1988c). Scientific basis for ecological standardization of the anthropogenic impact on marine ecosystems (using the example ofthe Baltic Seaecosystem. Oceanology2S(2). (in Russian) Izrael, Yu. A., Tsyban, A. V., Panov, G. V. & Chemyak, S. M. (1990). Microbial transformation of polychlorinated biphenyls in polar sea regions. DAN USSR (Reports ofthe USSR Academy of Sciences) 310. 502-506 . (in Russian) Jenkins, J. T. & Ephraums, J. J. (eds. ) ( 1990) Climate Change: The IPCC Scientific Assessment. Cambridge University Press, Cambridge. 26 pp. Lancelot, C, Billen. G.. Sourina. A., Weisse. T.. Colijn, F., Veldhuis, M. J. W., Davies, A. & Wassman, P. (1987). Phaeocystic blooms and nutrient environment in the continental coastal zones ofthe North Sea. Ambio 16. 38^6. Landner.L. (ed. )(1989). Chemicals in the aquatic environment: Advanced hazard assessment. Springer Verlag. Berlin, 569 pp. Manabe. S. & Stouffer. R. J. (1980). Sensitivity of a global climate model to an increase in CO, concentration in the atmosphere. J. Geophys. Res. 85, 5529-5554. Manabe, S. & Wetherald, R. T. (1980). On the distribution of climate change resulting from an increase in CO, content of the atmosphere. J. Atmos. Sci. 37, 99-1 18. Manabe, S. & Wetherald, R. T. ( 1 987). Large-scale changes of soil wetness induced by an increase in atmospheric carbon dioxide. J. Atmos. Sci. 44, 121 1-1235. Mantoura. R. F. C. & Riley. J. P. (1975). The use of gel- filtration in the study of metal binding of humic acids and related compounds. Anal. Chim. Acta 78, 183-200. McRoy, C. P. & Goering, J. J. (1976). Annual budget of primary production in the Bering Sea. Mar. Sci. Comm. 2, 255-267. Mitchell, J. F. B. ( 1988). Local effects of greenhouse gases. Nature 332, 399-400. Odum, G. ( 1986). Ecology, Vol. 2. Mir Publishers, Moscow, 359 pp. (in Russian) Oppenheimer, M. ( 1 989). Climate change and environmental pollution: Physical and biological interactions, dim. Change 15, 255-270. 13 Patin, S. A. (1979). The Impact of Pollution on Biological Resources and Productivity of the World Ocean. Pishchevaya Publishers, Moscow, I 1 1 pp. (in Russian) Pa.xeus, N. (1985). Studies on aquatic humic substances. Ph. D. thesis. University of Goetenburg, Sweden. Pierce, R. H.. Jr. ( 1974). p, p'-DDT-adsorption to suspended particulate matter in sea water. Geochim. Cosmochim. Acta 38, 1061-1073. Roots, E. F. (1989). Climate change: High-latitude regions. Clim. Change 15, 223-253. Roscigno, P. F. (ed. ) ( 1990). Residts of the Second Joint US- USSR Bering Sea Expedition. Summer 1984. US Fish Wild. Serv. Biol. Rep. 90( 13), 347 pp. Schlesinger, M. E. ( 1986). Equilibrium and transient climatic warming induced by increased atmospheric CO,. Clim. Dyn. 1, 35-53. Schlesinger, M. N. & Mitchell, J. F. B. ( 1987). Model projections of the equilibrium climate response to increased carbon dioxide. Rev. Geophxs. 25, 760-798. Sedlacek. J., Kallquist, T. & Gjessing, E. (1983). Effect of aquatic humus on uptake and toxicity of cadmium to Selemistrum capricormitum. In Aquatic and Terrestrial Humic Materials (R. F. Christmann & E. T. Gjessing, eds), pp. 495-516. Printz, Ann Arbor, Michigan. Siegenthaler, U. ( 1 989). Exchange of CO, between atmosphere and ocean. UNESCO technical papers in marine science 56, 44-49. Suess, E. (1980). Particulate organic carbon tlux in the oceans — surface productivity and oxygen utilization. Nature 288, 260-263. Sunda, W. G. & Lewis. J. A. M. ( 1 978). Effect of complexation by natural organic ligands on the toxicity of copper to a nmccWuVdx ^[gdiC.Monochreysisluthery. Limnol. Oceanogr. 23, 870-876. Tanabe, S. ( 1 985 ). Distribution, behavior and fate of PCBs in the marine environment. J. Oceanogr. Soc. Jpn. 41. 358-370. Troadec, J. P. ( 1989). Report of the Climate and Fisheries Workshop. Organized by M. H. Glantz, NCAR, Boulder, Colorado, 7-8, 16. Tsyban, A. V., Volodkovich, Yu. L. & Pfeiffere, M. Yu. ( 1985). Circulation of the contaminants in the Baltic Sea ecosystem. Investigation of the Baltic Sea ecosystem, pp. 244—257. Gidriimeteoizdut Publishers, Leningrad, (in Russian) US Environmental Protection Agency (1987). Chapter 12. An assessment of the effects of ultra-violet-B radiation on aquatic organisms (J. S. Hoffman, ed.), US EPA, 400-1-87- 001 C. Walsh, J. E. ( 1983). The role of sea ice in climatic variability: theories and evidence. Atmosphere and Ocean, March 2 1 . Whitledge, T. E., Bidigare, R. R., Zeeman, S. L, Sambrotto, R. N., Roscigno, P. F., Jensen, P. R., Brooks. J. M., Trees, C. & Veidt, D. M. (1988). Biological measurements and related chemical features in Soviet and United States regions of the Bering Sea. Cont. Shelf Res. 8, 1299-1319. Wilimovsky, N.J. ( 1974). Fishiesof the Bering Sea: The state of existing knowledge and effort. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelly, eds. ), pp. 243-256, University of Alaska, Fairbanks. Wilson. C. A. & Mitchell. J. F. B. (1987). A 2 x CO, climate sensitivity experiment with a global climate model including a simple ocean. J. Geophys. Res. 92(D1 1 ). 313-315. Zaitsev, Yu. P. (1970). Marine Neustonology. Naukova Dumka Publishers, Kiev, 264 pp. (in Russian) Zaitsev. Yu. P. ( 1980). Zooneuston and methods for its study. \n Methods for Biological Analysis of Sea Water and Bottom Sediments, pp. 134-139. Gidrometeoizdat Publishers, Leningrad, (in Russian) Zaitsev, Yu. P. ( 1985). Biotic contours in ocean monitoring. In Comprehensive Global Ocean Monitoring. Proceedings from the First International Symposium 2, 76-83. Gidrometeoizdat Publishers, Leningrad . (in Russian) Zika, K. G. ( 1989). The role of photochemical processes in the air/sea exchange of chemical species. UNESCO Technical Report. 14 Chapter 2: OCEANOGRAPHY Editors: LAWRENCE K. COACHMAN & VIKTOR V. SHIGAEV 2.1 Northern Bering-Chukchi Sea Ecosystem: The Physical Basis LAWRENCE K. COACHMAN^ and VIKTOR V. SHIGAEV^ 'School of Oceanography, University of Washington, Seattle, Washington, USA • Institute of Global Climate and Ecology, State Committee for Hydrometeorology and Academy of Sciences, Moscow. USSR Introduction The northern Bering and Chukchi Seas, encompassing the Bering Strait (Fig. 1 ). together constitute the most enormous shelf sea of the World Ocean — that is, over 1,000 km in north- south extent with depths less than 100 m. The longer-term (>1 month) average flow is northward of Bering Sea water across the whole area into the Arctic Ocean, providing the Northern Hemisphere oceanic link between Pacific and Atlantic Ocean systems. It has been known that North America and Asia are separated by the Bering Strait since Simeon Dezhnev transited the strait inadvertently (blown by a storm) in 1648; and that the general flow of the water through the strait is northward since the voyages of Bering and Cook in the 18th century. 178* 180* 173" t7S* 164- I6r iW 158* ISA* 76' leO- I7B' 176* 174- 17;- 170" i68' i66- lei* Fig. 1. Bathymetry of the northern Bering and Chukchi Seas. Modem studies of the physical oceanography of various parts of this large regime, begun in the 1930"s by G. E. Ratmanov ( 19,^7a,b) and C. A. Barnes (Barnes & Thompson, 1938), were )iyn[he^izedinBering Strait: The Regional Physical Oceanography {Coachman etal., 1975). This study summarized the water masses, theirdistributions, something of the temporal and spatial variations in properties and causes thereof, and quantified the northward flow and its variations. It showed the integrated nature of the whole system: that the waters and its transported properties were intimately connected across the entire shelf sea from the Bering Sea basin to the Arctic Ocean and that the dominant property distribution inechanism is everywhere is advection (with the generally northward flow). Investigations of various biochemical properties within the region, from which the production of organic matter and its subsequent fate can be determined and explained, began much later than the physical studies. These were also much more piecemeal and limited in scope until the advent of the Inner Shelf Transfer and Recycling Program (ISHTAR) in 1985 (Walsh et al.. 1990), which undertook an integrated physical/chemical/biological study (i.e., ineasuremenls of all fundamentals of the basic ecosystem) of those portions of the region to which they had access, viz. the Chirikov basin and eastern part of the Chukchi Sea. The results from ISHTAR, after four years of intensive sampling and analysis, clearly demonstrate that the whole region, integrated into one regime by the north advection, is also integrated as an enormous ecosystem containing some of the highest primary production values ever measured in the World Ocean. The ecosystem is sketched schematically in Fig. 2. The generally northward' water flow is composed mostly of water from the northern Bering Sea basin, which enters the region in the Fig. 2. Schematic of the northern Bering Sea ecosystem. Open arrows indicate advection along which ecosystem activity is aligned; dashed Imes encompass the three production/deposition centers. 17 Gulf of Anadyr. The continuity of this flow, entirely through the system into the Arctic Ocean, provides integration between three serially-aligned production/deposition/regeneration centers; the output of the upstream Gulf of Anadyr center materially effects the biochemical activity of the Chirikov basin center, which in turn feeds the center in the Chukchi Sea. Confirmation of the integrated nature of the ecosystem is provided by measurements made during the first synoptic survey of the whole region from the Gulf of Anadyr through the southern Chukchi. The opportunity arose from amalgamation of ISHTAR into the Third Joint US-USSR Bering & Chukchi Seas E.\pedition, 25 July-2 September 1988, on board the research vessel (RfV ) Akademik Korolev (Korolev). The areal distribution of integrated chlorophyll ( Fig. 3 ) clearly shows in essence the ecosystem arrangement sketched in Fig. 2 — three high-production centers arranged sequentially along the pathway of flow of Bering Sea water from the northern Bering through the Gulf of Anadyr, then the Chirikov basin and Bering Strait, and on through the southern Chukchi. Thus, we are dealing with a single ecosystem. It is the purpose of this paper to describe, to the extent of current knowledge, the physical basis of this ecosystem: the water masses and their characteristics, the flow field, and the variabilities of the physical features. The paper concludes with a discussion of the downstream end of the system in the Chukchi Sea, about which very little is as yet known. 175° 165° 160° Fig. }. Integrated chlorophyll from the cruise odheAkmleinik K(iroU'\\ August 1988. Notice the three major production centers, and the edge of a fourth area of high chlorophyll biomass off Kolyuchm Bay in the Chukchi Sea (after Springer, McRoy & Whitledge, in press). Water Masses Salinity is the variable delimiting the water masses because in the colder high-latitude waters, it, rather than temperature, has the primary influence on water density. Based on sources and modifications, there are three water masses fundamental to the sy.stem (Coachman el ai. 1975), and it is convenient to define two others, more local products of modifications. The three basic water masses, Alaskan Coastal, Bering Shelf, and Anadyr Current, are arranged side-by-side in the east-west direction. Identification ofthe water mas.ses obtained at any particular time are done from T/S diagrams of stations from sections crossing Anadyr and Shpanberg Straits; these capture the characteristics of the three basic water masses at the same time. Figure 4 shows an example. Typically, in the T/S plane, values beneath the surface layer fall naturally into three groups; a group with intermediate values of S but very cold; and somewhat warmer groups to each side, both less and more saline. Spatial continuity shows the least saline group ( Alaskan Coastal) to occupy the eastern part of Shpanberg Strait, the most saline group ( Anadyr Current ) are always stationed in the western part of Anadyr Strait, while Bering Shelf water of intermediate salinities can usually be found near both ends of St. Lawrence Island. Thus, from Fig. 4, the ranges of salinity for the three water masses were Anadyr Current — 33.0 to 32.75; Bering Shelf— 32.75 to 3 1 .9 ; Alaskan Coastal— <3 1 .9. ALASKAN COASTAL 31 32 SALINITY %o Fig. 4. T/S diagram of stations crossing Anadyr and Shpanberg Straits, illustrating the definition of the basic water masses. Station numbers are at the bottom of each water mass curve. Notice the natural separation into three salinity groups. But salinity values of the water masses are not constant. There is a seasonal cycle because runoff at these high latitudes is markedly seasonal. Yukon River discharge peaks in June, when the flow grows in about one month's time to two orders of magnitude greater than in winter. The regional north flow is insufficient to flush all of this freshwater from the system immediately, so part of the freshwater accumulates over the summer and is only completely flushed by late fall (Coachman t'l ai. 1975). This effects primarily salinities of Alaskan 18 Coastal water and to a lesser extent Bering Shelf water; both these water masses show a decrease in S over the summer, which can amount to as much as one-half part per thousand. There are also interannual variations in the water mass salinities that are the same magnitude as those of the seasonal cycle (about 0.5). Figure 5 showstherangesofS values for the water masses for all the years when sections in June or early July encompassing Anadyr and Shpanberg Straits have been taken; similar times of year must be compared to avoid the seasonal variations. We see that, interannually, the salinities are not constant. Small year-to-year differences are probably not significant because definition of water mass boundary values can sometimes be somewhat fuzzy, but the long-term variation with either a 10 or 20-year period is definitely real. Anadyr Current water in the 1960"s frequently had S values >33.0, but during the 1970's and beginning of the 1980's, values this high were never observed; only in 1988 have salinities >33 reappeared. Similar sized interannual variations in S have also been observed in the central shelf water of the southeast Bering Sea Shelf; ranges of S observed there (Coachman, 1986) are also plotted in Fig. 5. Clearly we are seeing the effects of large-scale climatic fluctuation causing similar property variations ovei; the entire Bering Sea Shelf. This variation effects also the bottom water temperatures of central shelf waters, and the T and S are correlated — wanner with more saline and colder with fresher. The few measurements available of bottom water temperatures in the central Gulf of Anadyr, where the coldest water of the whole Bering Sea Shelf is always found (the so- called "cold center" of the Bering Sea; Barnes & Thompson, 1938), suggest an interannual variation incoldestTof at least 2°C may obtain, not unlike that of T on the southeast shelf (Fig. 5). The interannual climate variation is also manifested in interannual variablity of ice cover of the Bering Shelf, which is primarily responsible for establishing the T and S conditions of bottom waters for the following year: minimum ice/warmer bottom temperatures/more saline, and vice versa. ^m^ Southeast Central Shelf Bottom Woter T Ronge J Southeast Central Shelf Water S Range ;^ 0 I960 65 Fig. 5. Interannual variation ofsalinity ranges ofthclhrec basic water masses. Over the 2.'i years of observations, water masses were most saline in the late I960's, and least saline in the mid-mVO's. Temperatures and salinities of southeastern Bering Shelf water suggest similar variations, showing the changes to be part of a large-scale climatic variation. The water mass sources are all to the south of the northern shelf area, and the advection carries them northward. As Alaskan Coastal, Bering Shelf, and Anadyr Current water masses are arranged sequentially east to west and there is very little lateral mixing or diffusion in the system, these waters maintain their east to west relationship as they are advected north. Figure 6 shows their distribution during August 1988, based on the Korolev data. The water masses were distinguished primarily by salinity of the deeper water, but temperature and water column structure (depth and degree of layering) were also considered. Anadyr Current water mass (Fig. 6, 1) originates from water of the Bering Slope Current (Kinder et ai, 1975), a branch of which enters the Gulf of Anadyr in the west near Cape Navarin. This water hugs the western Siberian shore and remains identifiable as a distinct entity to Bering Strait. North of this strait, the water merges with and becomes indistinguishable from Bering Shelf water. "180 175° 170° 165° 160° Fig. 6. Spatial distribution of water masses in August 1988 (Korolev liala). I: Anadyr Current. II: Bering Shelf. Ill: Alaskan Coastal. IV: Gulf of Anadyr. V: Siberian Coastal. On the east side of the system, Alaskan Coastal water (Fig. 6, III) originates well to the south of the region. It has the lowest salinities because it is the recipient of runoff from all along the coast, from the rivers of Bristol Bay and the Kuskokwim River. As Alaskan Coastal water enters the region, additions of Yukon River water near the east side of Shpanberg Strait "reinforce" the low salinities, which happens again when the water passes through Kotzebue Sound north of Bering Strait. Thus some parts of this water mass can become quite fresh in late summer (S<30), and its area expands westward, but by the following winter the freshwater has flushed from the system and Alaskan Coastal water salinities are again >32. Bering Shelf water (Fig. 6, II) is the resident water mass of the whole central shelf region south of St. Lawrence Island. The waters filling the central shelf are basically mixtures of the two extremes: least saline coastal water and the most saline 19 water from the Bering Sea basin Shelf edge. Advection is small over the whole central shelf with water depths between 50 and 100 m (Coachman, 1986), so this water mass, intermediate in salinity and with long residence times, is most strongly conditioned by climatic factors such as brine rejection due to freezing and degree days of frost (see discussion in Coachman, 1986). Furthermore, Bering Shelf water in the area immediately south of St. Lawrence Island is directly influenced by special freezing conditions associated with the large polynya always found on its south side (Schumacher et al., 1983). In the area of this polynya, the freezing over-winter of the equivalent of 8 to 10 m of ice causes a substantial increase in salinities of the shallow watercolumns. Thus increased in density, some of this water moves away to the southwest (in the direction of deepening) into the central Gulf of Anadyr, where it can be distinguished as a separate water mass we call Gulf of Anadyr water (Fig. 6, IV); this is in fact the "cold center" water of Barnes and Thompson because its temperatures over the summer normally remain close to freezing (<- 1 .5°C) and are the coldest observed anywhere on the whole Bering Sea Shelf. Most of the year. Bering Shelf water (Fig. 6, II) moves north around both ends of St. Lawrence Island and then occupies the middle area between Alaskan Coastal and Anadyr Current waters. In late summer, however, some years Alaskan Coastal water expands to nearly fill Shpanberg Strait, as in late August 1988, and northward transport of Bering Shelf at these times is predominately through Anadyr Strait (Fig. 6). North of Bering Strait, Anadyr Current water becomes so blended with the shelf water it loses identity. Across the Chukchi Sea we continue to identify this water mixture as Bering Shelf water , because salinities are little altered by the admixture of Anadyr water, and the name connotes its basic origin. In the Chukchi Sea occurs another water mass, Siberian Coastal water (Fig. 6. V), identified by values of salinity greater than any entering the sea through Bering Strait contemporaneously. For example, in August 1988, the maximum observed S in Anadyr Current water was <33.0, while salinities ofSiberian Coastal water were up to 33.6. This water mass is associated with the Siberian Coastal Current. Though lateral mixing is in general quite small in this regime of strong advection, and relatively discrete boundaries obtain between the water masses (transitions between two water masses are typically complete in <10 km), there is some lateral interaction. This almost always takes the form of layering, the slightly heavier water mass on one side encroaches under the neighboring water, which fonns a lighter surface water layer; or, frequently, the lighter water mass is driven by wind over the heavier. Layering varies seasonally. In winter and spring there is practically none; all the shallow watercolumns are well mixed. Nomially only in deeper areas like the central Gulf of Anadyr does a layered structure survive the winter cooling and freezing. Layered water columns appear with the advent of freshwater accumulation and some seasonal warming, usually late June and July, and is most widespread at the end of summer before fall cooling begins. The extent and degree of layering observed in August 1988 (Fig. 7) is typical for late season. We make the following points and interpretations: /. Strong layering is typical of the boundary between Alaskan Coastal and Bering Shelf water, particularly in the Chirikov basin (cf Fig. 6). 2. Layering is minimal in very shallow near-shore waters, (e.g., in eastern Kotzebue Sound). 3. Both the Gulf of Anadyr and Siberian Coastal are basically layered water masses. In the Gulf of Anadyr depths in the central part deepen to 100 m (Fig. 1 ). Here the very cold water of the "cold center," with slightly enhanced salinities, resides beneath Bering Shelf water; water columns are sufficiently deep that the layering survives rigorous winter cooling and freezing. During the summer along the Siberian coast in the Chukchi Sea, runoff and ice melt create a very light, low salinity surface layer over the high salinity water at bottom; both layers are part of the Siberian Coastal Current. 4. Minimum stratification, even in late summer, is always observed directly downstream from Anadyr and Bering Straits, a consequence of turbulent energy generated in these constrictions. We can now positively show that all waters of the ecosystem derive from a single source, the water of the Bering Slope Current of the northern Bering Sea. During the Third Joint US- USSR Bering & Chukchi Seas Expedition, samples from all the water masses were analyzed for "O heavy oxygen isotope. Two factors make these measurements diagnostic for water mass analysis: 70' SALINITY LAYERING S130m) - SlOml. %o AUGUST 1988 °I80 175° 170° 165° 160° Fig. 7. Salinity layering (S at 30 m minus S near-surface) in August 1988. The distribution is typical: strong layering in the central Gulf of Anadyr (deeper water), along the boundary between Bering Shelf and Alaskan Coastal in the Chirikov basin, and in the Siberian Coastal Current. Very little layering in shallow water near Alaska, and in two plumes extending downstream from Anadyr and Bering Straits. 20 /. This stable isotope is most abundant in ocean water and least abundant in fresh precipitation and runoff, and so mixtures show intennediate values in proportion, just like salinity; and 2. the freezing process, which is important in increasing salinity of the northern shelf waters, does not alter the isotope abundance. The correlations between salinity and oxygen isotope for the water masses are plotted in Fig. 8 (oxygen isotope data from Grebmeier et ai, 1990). Isotope values are plotted as deviations from standard mean ocean water ('^Osmow)- so that most ocean waters have values close to 0 and freshwater is <-20 ppt. In Fig. 8, samples are plotted in two ways: as individual point correlations for samples from the Bering Slope Current (triangles), Alaskan Coastal (open circles) and Siberian Coastal (solid circles) water masses, and as envelopes encompassing many values for the other three. All samples lie on or very close to a line from S = 35, "*0 = 0 (ocean water) and S = 0, '"O = -24.6 (freshwater), from which we can conclude that all water masses are essentially simple dilutions of the most saline Bering Slope Current water by freshwater. The progression along the line is orderly. The v'8. S 0/SALINITY ANADYR CURRENT BERING SLOPE CURRENT GULF OF ANADYR •• SIBERIAN COASTAL WATER ALASKAN COASTAL O 31 32 33 34 BOTTOM WATER SALINITY. 7oo Fig. 8. Correlation of '"O with salinity. Koriilev cruise, August 1988. All water masses of the Northern Bering Sea Ecosystem are dilutions to varying degrees of Bering Slope Current water by freshwater. Gulf of Anadyr and Siberian Coastal waters are modifications of Bering Shelf water through salinity enhancement due to freezing. Arrows indicate direction of water mass modification. Data from Grebmeier. Cooper & DeNiro, 1990. precursor water to the whole system from the Bering Slope Current has both the highest salinities and abundances of '"O: S ~ 33 to 33.2, '"O - -1.5. These values are, of course, already slightly diluted from SMOW. In the ecosystem, the first step in dilution is observed in the Anadyr Current, because the current mixes to some extent with runoff (particularly the Anadyr River) in its transit around the Gulf of Anadyr. |In Fig. 8, the pathways of water mass modification are indicated by arrows.] Furtherdilution of AnadyrCurrent water produces the Bering Shelf water inass, ubiquitous to the whole northern shelf. Not all AnadyrCurrent water transits Anadyr Strait, but some is detlected to the south of St. Lawrence Island, where it meets and mixes with fresher waters from the Alaskan side of the system, forming this water mass with slightly reduced salinities and '"O. Samples from the Alaskan Coastal water mass show much greater and more variable dilutions because of proximity to the high runoff along the eastern side of the system. They also do not follow the dilution curve as closely because selected areas are subject to strong local freezing and brine rejection, for example within Norton Sound ( see Muench et ill.. 1981 ). The value at -3.3/31.5 is a good case in point. The two secondary water masses of the system. Gulf of Anadyr and Siberian Coastal, are both created from Bering Shelf water through salinity enhancement by freezing. The polynya south of St. Lawrence Island, as discussed , is the focal point for the salinity enhancement which turns Bering Shelf water into Gulf of Anadyr water ; the overwinter freezing increases salinities by about 0.5 but without changing "O. The Siberian Coastal water mass is apparently created in the same way. Bering Shelf water travels throughout the system, well north into the Chukchi Sea, without appreciable change in S. The whole system evidences very little lateral diffusion and exchange between water masses, and the Bering Shelf water, sandwiched in the middle, is effectively isolated from runoff and hence dilution from both Alaska and Siberia. In the Chukchi, vigorous freezing in certain areas in winter causes substantial increases in S values without modifying '*0, and this water is recirculated the following year as part of the Siberian Coastal Current (see discussion below). Flow Field The Anadyr Current, the branch of the Bering Slope Current that enters the Gulf of Anadyr near Cape Navarin and continuously supplies the nutrients to fuel the ecosystem, is a topographic boundary current of the eastern Bering Sea Shelf; it is also, coincidentally, located along the western boundary of the shelf. This was convincingly demonstrated by Kinder e/ al. ( 1986) who employed both laboratory models and numerical simulations, achieving results in very close agreement with what we know of the Anadyr Current. The basic driving force is the sink for Bering Sea water imposed by the northward flow through Bering Strait — that is, the pressure head created by a -0.5 m height difference between the Bering Sea and the Arctic Ocean (Stigebrandt, 1984). Thus, Bering Sea water must move northward across a shoaling topography. In this situation, the topographic gradient, f / h ~ 5 X 10 '' cm ' s ', is more than an order greater than the variation of Coriolis parameter, (3 ~ 1 x 10" cm' s '. The across-shelf flow is concentrated as a current along the lefthand boundary facing upslope (Fig. 9). Notice in the simulations that regardless of whether or not flow conditions are imposed along the Bering Sea slope, the cross-shelf flow still forms the same western boundary current on the shelL The numerical simulations indicated a current width of 50 km and speeds of 10-20 cm s ', both in excellent agreement with available data on the real current. Of course, within the Gulf of Anadyr, the flow, being strongly steered along isobaths, actually circulates clockwise around the gulf (cf. Fig. 1 ). Variability in flow of the Anadyr current is unknown. It seems probable, however, that it is a much steadier flow than those through Anadyr and Bering Straits. The large variability in the latter flows, predominantly at periods of a day to a week. 21 NUMERICAL SIMULATIONS OF BERING SHELF CIRCULATION BRING 3 I — -y SIMIT ALASI 0.7. In early summer each year, though, the correlation breaks down. Regional winds become light, without strong variations, the flow becomes decoupled from the wind, and the currents are stronger and directed more steadily to the north (Coachman & Aagaard, 1988). These are the conditions for short residence times, and were observed to obtain at the beginning of July each year. Over the remainder of the year, winds are both stronger and more variable, and the flow is driven into variations that are reasonably correlated with those of the wind. Thus the periods of slow and reversed (southward) How become more frequent, and residence times become markedly longer. This changeover from "summer" to normal wind regime occured at different timesbetween the beginning and end of August in 1985, 1987, and 1988. Nineteen eighty-six, however, was anomolous; the typical "suinmer" flow condition, decoupled from the wind, never really developed. The resulting longer residence times over the production season were undoubtedly responsible for the greater accumulation of biomass in the Chirikov than in the southeastern Chukchi basin in 1986, as opposed to more "normal" years when more accuinulates in the Chukchi ( Walsh £'/«/., 1989). To provide more insight as to specific wind conditions causing longer residence times. Fig. 13 was prepared. First, the north-south component of wind at Bering Strait was examined by itself, but no relationship with residence tiines was apparent. The forces driving the flow field variations are obviously more complex than just the local wind in Bering Strait. So the wind at Anadyr Strait was added, and a qualitative picture emerges. A primary condition for long residence times seems to be a sustained trend of change in the winds to northerlies (i.e., directed to the south) combined with a sustained, strong divergence of the wind field over the Chirikov basin. The divergence is where the winds at Anadyr are either less strong to the north, or stronger to the south, than those at Bering Strait. Under these conditions, the normal sea surface slope down to the north is negated and readily reversed. Without a "push" from the south, water parcels can hang around in the Chirikov basin for very long times (as long as two months). Fig. 13. North-south component of winds at Bermg Strait and Anadyr Strait over the summers of 1985-87 (data smoothed with S-point runnning means). Long residence times seem to be associated with changes toward strong south-directed winds and a sustained, strong divergence of the wind field over the Chirikov basin (hachured). Chukchi Sea The third, downstream production center of the northern Bering Sea ecosystem is in the Chukchi Sea. ISHTAR has studied the southeast comer of the region. Southwest from Pt. Hope lies a production center where huge chlorophyll biomass has been measured (cf. Fig. 3) and also some of the 24 highest values of prhiiary productivity ever measured in the World Ocean. Fuel for this production center is provided by Bering Shelf water. The water mass transits Bering Strait (where it becomes combined with the Anadyr Current water mass; see Coachman et al.. 1975) and circulates counterclockwise around Kotzebue Sound following the bathymetry (cf. Fig. 1). It still contains, in spite of high utilization upstream, considerable nutrients (e.g., -10 |i g-at NO,/l). The cruise of the Akademik Korolev expanded the studies to the west as far as Kolyuchin Bay. The most important finding was another center of production in addition to that southwest of Pt. Hope (Fig. 14), which was associated with an entirely different water mass. The maximum observed salinity of Bering Shelf/ Anadyr Current water in 1 988 was <33, while the salinities of the water of the center off Kolyuchin were up to 33.6 (Fig. 14. lower). At this time the Siberian Coastal Current did not extend all the way to Bering Strait, as demonstrated in the salinity distribution (Fig. 14, lower). The values >32. 9 stopped about 1 00 km short ofthe strait; apparently the current turns east and northeast, closing a gyre with the Bering Shelf water flow to the northwest, southwest of Pt. Hope (cf. Fig. 2). There are times, however, when the Siberian Coastal Current does reach to Bering Strait; Ratmanov (1937b) documented penetration of Siberian Coastal water into the strait in 1933. Fig. 14. Average chloroptiyll biomass (upper) and maximum S in the water column (lower) in the southeastern Chukchi Sea, Korolev data, August 1988. Note high chlorophyll off Kotyuchin Bay in addition to the center southwest of Pt. Hope, associated with water with higher salinity than any entering through Bering Strait. Thus, the full extent ofthe production area ofthe northern Bering Sea ecosystem in the Chukchi Sea is unknown. It is clearly much larger than previously envisioned. It is fueled by two different water masses — the Bering Shelf water from the south entering directly through Bering Strait, and a Siberian Coastal water associated with the Siberian Coastal Current. Prime questions are the source and extent ofthe latter. Few data are available to help search for the source; the best are from the cruise of the USCGC Norihwliul in 1963 (US Coast Guard Oceanographic Unit, 1965). Figure 15 plots the salinities (upper) and nitrates (lower), averaged for the water columns >20 ni, from these data for the Chukchi Sea and Long Strait. The distributions in August 1963 appear to be the saine as in 1988. A water mass with salinities greater than any coming into the system from the south follow the Siberian coast. There is a focal point for this water near Wrangel Island; T/S analysis ( Fig. 16) shows the water mass is not extant in the East-Siberian Sea to the west, but in fact shows the highest salinities at the stations in Long Strait, close to Wrangel Island. High nutrient concentrations are associated with this water; it is obviously this water that is responsible for the second region of production in the Chukchi Sea part ofthe ecosystem. The apparent source of this water in the vicinity of Wrangel Island is confirmed by sketchy data from three other cruises (Fig. 17): the Maud in 1922 (Sverdrup, 1929), Northwind in 1962 (US Coast Guard Oceanographic Unit, \%A).imdOshoru Maru'm 1972 (Faculty of Fisheries, 1974). It appears that the whole area east of Wrangel Island shows evidence of this high salinity water mass. MAXlMUf^ S in water column NORTHWIND 8-16 AUG 1963 180° 175° 170° Fig. LS. Maximum S (upper) and nitrate concentration (lower) from the Nonhwiiid. August 1963. The high S water has high nitrates, and seems to he coming from the vicinity of Wrangel Island. 25 CHUKCHI SEA NORTHWIND 8-16 AUG 1963 Where does this water come from? One possibiUty hypothesized initially was that the source of the water mass may be the pycnochne layer of the Arctic Ocean. The focal areaeast of Wrangel Island is the head of the Herald Submarine Canyon, which indents the Chukchi Shelf near Herald Island (see Fig. 1). The concept was that Arctic Ocean water might flow in-canyon along the bottom onto the shelf, as it does in Barrow Canyon on the eastern side of the Chukchi (Mountain et al., 1976). This hypothesis can be ruled out because the phosphate content of the Siberian Coastal water mass is much too low to be Arctic Ocean water. The most likely hypothesis is that the water mass is of Bering Sea origin. It is Bering Shelf water that enters the Chukchi Sea during fall and winter, where its salinities are enhanced through ice formation. Then the following summer the water is recirculated throughout the southern Chukchi Sea via the Siberian Coastal Current. Two observations in support of this hypothesis are: 7. the '"O values of the water are precisely those of Bering Shelf water (Fig. 8); and2. the focal point of highest salinities east of Wrangel Island is an area where the least amount of ice formation in winter is required to enhance salinities to the requisite -33.5 (Fig. 18). Fig. 16. T/S correlations for the Mir//iu(>(i/data. Individual lines are all stations in the Chukchi Sea; stations from Bering Strait and the East-Siberian Sea are enclosed in envelopes. Stations from Long Strait ( marked, see Fig. \5) have the highest S values of all. 13V -SO' Fig. 1 8. The amount of ice growth required to raise the salinity of water columns to 3.^.5 "/(x) . Notice the area of minimum necessary ice growth coincides with the area of highest salinities near Wrangel Island and Herald Shoal (from Aagaard, Coachman & Carmack, 1981 ). Fig. 17. Confirmation that the source of high salinity (and high nutrient) water is near Wrangel Island and Herald Shoal to its east side. Data from three cruises: (upper) Miiiid. 1922; (lower lelll Nurllmiiid. 1962; (lower right) Osharn Maru, 1972. With this hypothesis, the relatively high nutrient concentrations are supplied by the rich Bering Shelf water in winter that are not utilized or affected by freezing, so are available to fuel the Chukchi Sea end of the ecosystem the next summer. The circulation, insofar as it is known (Fig. 19). fits in with this hypothesis, though there must be more southerly components of flow in the western Chukchi, southwest of Herald Shoal, than indicated in the schematic depiction. The presence of the highest salinities near Herald Shoal, and particularly to its west and southwest, is not coincidence; the shoal water is undoubtably important in providing the most effective environment for salinity enhancement by freezing. 26 178" 176" 174*' I72« 170" 168" 166" 164" 162" 160" 158" 156" ^ — - VARIABLE — • — • "CORES" (vonoua posi ifions) / V 178" 176° 174° 172° 170° 168° 166° 164° 162° 160° 158° 156° Fig. 19. A best guess of the circulation in the Chukchi Sea (from Coachman, Aagaard & Tripp, 1975). Notice that Herald Island and Shoal are in the main pathway of Bering Shell water. However, there actually must be more movement of water toward the Siberian Coast near Wrangel Island than suggested in this schematic. L'envoi We have summarized the important physical oceanographic factors of the northern Bering Sea ecosystem. A unique set of features combine to make it one of the World Ocean's largest and most productive ecosystems. The key feature is advection of waterfrom a rich pool of nutrients (the Bering Sea Continental Shelf edge), across an enormous distance in shallow water. The nutrient supply continuously injected by the current is sufficient that they never become depleted and limiting, even with high production. There are two constrictions in the advective stream, dividing the system into three basins and three production centers. These are spaced such that the transit time of water across each basin, two to four weeks, is the same as a complete biological production-utilization-regeneration cycle. Turbulent energy injected into the water columns at the constrictions stirs them, "resetting" the system for the next round of production. The advection is driven northward from the Bering Sea into the Arctic Ocean by a sea surt'ace slope (the Arctic Ocean stands lower than the Bering). But there are important variations in the transport related to the local winds, which drive water against the land boundaries modifying the surface slope. Primary variations are over a few days (storm time scale), and as these are greatest and most frequent in winter, there is a seasonal cycle of lower net north transport in winter and greater in summer. Interannual variations are also significant. They affect mostly the geographically constricted Chirikov basin; here water parcel transit (residence) times can differ by a factor of five. The variability seems to have only a small influence on the actual amount of primary production in the ecosystem; rather, its importance lies in varying the amount of production that becomes deposited in the centers versus the amount that is transported through into the Arctic Ocean. The downstream (Chukchi Sea) end of the ecosystem is virtually unknown. Nutrients supporting very large production are supplied to this center by Bering Shelf water entering directly via Bering Strait and from a second source presumed to be Bering Shelf water enhanced in salt content through freezing during the previous winter and recirculated via the Siberian Coastal Current. But this is hypothesis; the circulation of the Chukchi is not known, nor the amount and extent of production, nor the amount of carbon that is exported to the Arctic Ocean. Considering the possible significant role of Chukchi Sea carbon export in global carbon budgets and climate warming (Walsh el cil.. 1989), further study of the Chukchi Sea end of the northern Bering Sea ecosystem has a very high priority. 2.2 Water Mass Modification from the Bering into the Chukchi Sea ANTHONY F. AMOS' and LAWRENCE K. COACHMAN* 'Marine Science Institute. University of Texas. Port Aransas. USA ' School of Oceanography. University of Washington. Seattle. USA Introduction The only Northern Hemisphere connection between the Pacific and Atlantic Oceans is across the shallow waters of the northern Bering and Chukchi Seas connected by the Bering Strait. The seminal work on the oceanography of the northern Bering Sea (Barnes & Thompson, 1938) led to further investigations on this important region that continue to this day. Coachman et al. (1975) reviewed the regional physical oceanography in the most comprehensive work on the Bering 27 Strait region to date. Studies since tiien. notably the Inner siielf Transfer and Recycling (ISHTAR) program iiave expanded our understanding of the regional oceanography yet further (Coachman, 1986: Walsh ^/ a/., 1989). Complete, integrated studies of the region have been restricted by its strategic significance, national boundaries, and Exclusive Economic Zones. The Third Joint US-USSR Bering & Chukchi Seas Expedition on the Soviet research vessel Akademik Korolev (Korolev) in the summer of 1988 (AK-47) afforded an opportunity for US and Soviet scientists to study the oceanography of the northern Bering/Chukchi Seas without limitations imposed by territorial boundaries. The cruise took place from 26 July to 2 September 1 988 and occupied 1 02 CTD stations in the Gulf of Anadyr, Chirikov basin, and southern Chukchi Sea (see Frontispiece). (An additional 1 1 stations were occupied near the Aleutian Islands and in deep parts of the Bering Sea, but are not discussed here.) There are three primary water masses in the northern Bering Sea, and the basis for their identification is salinity (Coachman et ai, 1975). The most saline is water from the continental slope of the eastern Bering Sea Shelf edge, which enters the region via the Gulf of Anadyr and Anadyr Strait to the west of St. Lawrence Island. This is the most important water source to the extremely productive northern Bering/Chukchi Sea ecosystem because of its high nutrient loading. The least saline water lies in the east, the Alaskan Coastal water, which flows parallel to the Alaskan coast northward through Shpanberg Strait to the east of St. Lawrence Island. The water mass of intermediate salinity, which is also the coldest, is Bering Shelf water in residence over the extensive shelf area south of St. Lawrence Island. It is advected northward around both ends of St. Lawrence, through both Anadyr and Shpanberg Straits, and northward between the other two; part of the water mass modification occuring in the system is com- mingling of these three water masses as they are advected northward. Salinity valuesof the water masses are not only space, but time-variable, as much as 0.5 ppt seasonally and interannually. Thus, in the absence of quasi-synoptic data from the whole system, the precise changes of water mass properties as they transit the various basins and straits have never been observed. As the Korolev data provide the first-ever quasi-synoptic picture of the regional water masses, this paper describes their modification as they are advected north from the shelf break of the Bering Sea through the Gulf of Anadyr, Chirikov basin, and the southern Chukchi Sea. Methods Conductivity-temperature-depth (CTD) casts were made surface-to-bottom using a Sea-Bird Electronics model SBE-9 system with a General Oceanics RMS 1 2 rosette water sampler. The rosette held 1 2, 2.5-liter "GO-FLO" water sampling bottles. These provided water samples for many other projects as well as samples for salinity analysis to compare with the CTD values. The salinity measurements were made usinga Beckman RS7-C laboratory salinometer. The Sea-Bird was delivered new, just two weeks before AK-47 began. It has a rated accuracy of 0.004°C/year over the range -5 to H-35°C, 0.0003 S/m/month over the range 0 to 7 S/m, and 0.02% of full scale over the depth range 0-3,500 m. The instrument was calibrated by the US Northwest Calibration Center in Seattle before and immediately following the Korolev cruise, with nearly no changes in output. Later, the same CTD was used in the Antarctic, where salinities from some 1 ,000 points were compared with samples run on AGE and Guildline salinometers — differences were less than 0.01 ppt. Subsequent calibrations have shown this instrument to be very stable and its accuracy is well within the tolerances acceptable for modem physical oceanographic research. Methods of CTD deployment and data reduction are pertinent to data quality, so they are outlined briefly. The CTD operator prepared the rosette and set up the computer about 15 min before each station. On station, the instrument was lowered to the sea surface (or up to 5 m below surface, depending on sea state) and held while the program to record data was started. It was then lowered at a rate between 1 5 and 30 m/min until it was about 5 m above the sea floor. When the instrument's attitude in the water column was seen to be stable, it was then lowered another 2 or 3 m. The computer was then reset for the uptrace, and the rosette bottles were tripped at predetermined depths on the upcast. Data is acquired by the Sea-Bird at a rate of 24 scans of pressure, temperature, and conductivity per second. For AK-47, scans were averaged in groups of six, giving four data groups per second to be recorded. At a drop rate of 30 m/min, CTD values were thus acquired approximately every 0. 1 25 m. The data are averaged internally, digitized, and transmitted to the ship via the center conductor in the sea cable through winch slip rings into the deck laboratory. The deck unit (Sea-Bird model 1 1) converts the data to computer-compatible signals, which are fed into a Packard-Bell AT-type computer via an IEEE 488 (GPIB) bus. Using Sea-Bird supplied software, the CTD data were displayed on the CRT monitor in real time as X-Y plots as the instrument was being lowered. As the rosette bottles were tripped on the upcast, the usual problems in calibrating the CTD conductivity sensor were encountered. Because of water disturbance on the upcast by the rosette and CTD housings, salinity readings by the CTD are suspect. Thus, comparison of salinity samples with the CTD output does not necessarily give valid in situ calibration data. Also, comparison with downcast values in shallow, highly variable shelf waters is likewise suspect. Nevertheless, at least two samples from each station were collected for checking the CTD calibration. An ancient Beckman salinometer was used to run these salinities, which presented problems with drift. In spite of all the difficulties, the results show /. consistency in Sea-Bird CTD output station-to-station; 2. close agreement with SEACAT data when the two instruments were run together; and 3. close agreement between CTD values and laboratory determinations, providing confidence in the accuracy of the data from AK-47. 28 Raw CTD data were recorded on the computer' s hard disk drive and archived on Iomega Bernoulli 20- Megabyte removable disk cartridges. One-meter average values for each station were created using Sea-Bird supplied software. A data report gives standard-level listings for all CTD data from the cruise (Amos. 1990). Results water depths in the Gulf of Anadyr are less than 1 50 m, and mostly less than 100 m. In the Chirikov basin and southern Chukchi Sea, water depths are even less — almost everywhere 30 m or less. The north-south size of this shallow shelf sea is enormous, subtending about 1,200 km from the shelfbreak in the northern Bering Sea to the shelfbreak in the Arctic Ocean. In this shelf sea, diverse water properties are encountered. Based on AK-47 data, in summer temperatures range from nearly 12°C at the surface near the Alaskan coast in the Chirikov basin, to -1.6°C at the bottom in the central Anadyr Gulf, southwest of St. Lawrence. Salinities range from 24 ppt at the surface near the Chukchi coast off Kolyuchin Bay to 33.6 ppt at the bottom in the same location (Station 45). A T/S diagram of all stations from AK-47 is shown in Fig. 1 . Surface values of each station are marked by "T" and bottom values by "B." and the dots are 1-m average values. This diagram includes not only the shelf stations but the 1 1 stations taken in the deep Bering Sea. These latter form a tight grouping: surface values are all >32 ppt up to about 33.4 ppt; there is a temperature minimum in the S band 33.2-33.4 (forming a marked ""V" shape in the diagram); deeper, there is a temperature maximum of 3.64°C, toward low salinities. A few stations with bottom water temperatures ~()°C and S's >33 ppt deviate from the mass of points. It has long been known that the main flow in the northern Bering Sea is northward through Bering Strait into the Arctic Ocean. Coachman and Shigaev (Subchapter 2.1, this volume) trace a primary pathway of this flow. Water from the Bering Slope Current, which tlows northwestward along the continental shelf edge of the eastern Bering Sea Shelf ( Kinder t'/ «/.. 1975), crosses the continental shelf southwest of St. Lawrence Island in the Gulf of Anadyr. The How maintains itselfas a current (transport -0.5 to 1 Sv) circumnavigating the gulf because its dynamics are analogous with tho.se of a western boundary current (Kinder et ciL. 1986). From the Strait of Anadyr, the flow follows the western side of Chirikov basin, transits Bering Strait, then curves northeastward into Kotzebue Sound before being steered by the topography to the north and west. The second main regional flow is that of coastal water on the east, entering through Shpanberg Strait east of St. Lawrence and hugging the Alaskan coast northward through Bering Strait, around Kotzebue Sound, and then northwest passed Pt. Hope and Cape Lisburne. Between these flows is advected a third water mass of shelf water; because this water mass is made on the large Bering Sea Shelf south of St. Lawrence through mixing of dilute coastal water with the more saline Bering Sea continental slope water, it is identifiable as a separate water mass by its intermediate values of salinity; it is also the coldest of the water masses in summer south of Bering Strait (cf. Coachman etal., 1975). The Korolev data provide the first quasi-synoptic coverage of all these water masses within the region, thus allowing quantitative as.sessment of the changes in temperature and salinity as they are advected northward from the Bering Sea into the Chukchi Sea. We now examine the water mass modifications basin by basin. GiilfofAiuutyr All CTD stations from the Gulf of Anadyr, together with Station 6 from the continental slope south of the gulf, are plotted in Fig. 2a. The latter is in the Bering Slope Current and thus shows the characteristics of this source water to the gulf. It has a water mass curve typical of the current; that is, a temperature minimum of ~2°C at S ~ 33.2 ppt, forming a "V" in T/S space, below which is a T maximum (T ~ 3.8°C at S ~ 33.7 ppt) followed by a T decrease and S increase to the deep basin bottom water type (T ~ 1.6°C; S ~ 34.7 ppt). Surface temperatures in the gulf are typically 6 to 8°C at this time of year, with salinities spread over the range 31.5 to 33 ppt. The spread in values reflects the nonconservative nature of properties in the upper layer with exchange across the sea surface, true in particular for temperature. 29 US/USSR BERING ANADYR ■88 LU CC D I- < cr UJ d LU 31 32 SALINITY (ppt) Fig. 2a. All CTD data (l-m average values) from the Gulf of Anadyr and Anadyr Strait stations, and Station 6 from the Bering Slope Current. Localized sources of dilution, the main source of freshwater being the Anadyr River entering midway along its western boundary , contribute to the spread in salinity values. Horizontal mixing of waters of the surface layer is evidently small. Bottom water values, on the other hand, are bunched much more tightly and cluster into two groups. One grouping is of cold water, <0°C, in the salinity range -32 to 32.7 ppt. The second group is wanner, ~0 to 2°C, and more saline, 32.7 to 33.3 ppt. When the spatial distribution of these stations is examined (cf . Frontispiece ), we see that the stations of the cold, lower S group are all from the middle of the gulf, centered around Stations 1 8 and 1 9, while the stations with warmer and more saline deep water are from around its perimeter, including Stations 12. 13 through 25. 26, 29, 31. and 33 to 38. Temperatures and salinities of the waters beneath the surface layer are conservative and are modified only through vertical and horizontal (lateral) mixing as the water masses transit the gulf. To expose the source water characteristics and their modifications within the gulf. Fig. 2b plots stations representative of each key water mass and location. The extreme of cold, lower salinity water is represented by Stations 18 and 19, from the central gulf. The temperatures are only about 0.1 to 0.2°C above freezing. This water is that of the "cold center" of the Bering Sea, identified already by Barnes and Thompson (1938). The water entering the gulf as the Anadyr Current is represented by Stations 12 and 13 close tp Cape Navarin. This water is from the Bering Slope Current (Station 6), which is the source of highest salinity water to the gulf; the source level lies in the depth range -50-200 m of the current. When the water mass enters the gulf off Cape Navarin. its characteristics are T ~ 1 to 2°C, S - 32.5 to 33 ppt. Thus, its propeilies have already been significantly modified in the 1 50 km transit across the shelf from the continental slope, not through surface exchange but through mixing with colder and less saline shelf water — the deep layers have been cooled - 1 .5 to 2°C and freshened -0.5 ppt. CL 1- < cr UJ -1 - GULF OF ANADYR CAPE NAVARIN ■18 1 BERING SHELF 19 I COLD CORE CENTER I I L 32 33 34 SALINITY Fig. 2b. T/S diagram of key stations from the Gulf of Anadyr; solid arrows indicate directions of major modifications. Most surface layer values arc not plotted. Water flowing north through Anadyr Strait is created from Bering Slope Current water by mi.xing with cold Bering Shelf water. The interaction is a two-stage process, first lateral layering (cf Station 29) followed by vertical mixing. This water mass then circumnavigates the perimeter of the Gulf of Anadyr following the bathymetric contours and interacting with water of the "cold center" enroute. The interaction is in two stages. First is a horizontal layering, or interleaving, of the less dense "cold center" water laterally above the denser water from the Bering Slope Current ( now the Anadyr Current). Station 29, halfway around the gulf, cleariy illustrates this stage of the interaction. Then vertical mixing becomes more effective, particulariy as the water masses are required to shoal to 50 m as they enter Anadyr Strait, and the result is homogenization into narrow ranges of T and S. When the water exits the gulf through Anadyr Strait it has essentially median values of T and S (Stations 39. 40). The two-stage interaction, layering followed by effective vertical mixing, conforms precisely with the model of water mass modification in the gulf proposed by Coachman et al. (1975). Chirikov basin All CTD data from the Chirikov basin, including Stations 39^3 from Anadyr Strait and 76-86 from Bering Strait, are shown in Fig. 3a. There is a concentration of bottom water values with temperatures -1 to 3°C in the S range 32.2 to 32.9 ppt. From these values, the remainder trend toward 30 US/USSR BERING '88 CHIHIKOV + Anadyr S Bering Straits tu cr D I- < cr D. z tu 10 /- 6 Fig. 30 31 32 33 SALINITY (ppt) 3a. All CTDdala{ 1-m average values) from the Chirikov basin, including Anadyr and Bering Straits. warmer and less saline values (to the upper left in the T/S, plane). Likewise, surface water values lie along the same general trend line. When the spatial distribution of stations is examined, we see that the colder, more saline water is associated with stations from the west side of the basin, while the warmer, least saline water is all on the eastern side. The Chirikov basin is a little shoaler on the east side, 30 m grading downward to nearly 50 m off Siberia. The freshwater sources to the water masses in the basin are essentially confined to the eastern side — the Yukon River and other runoff from the Alaskan coast. The freshwater generates layering in the water masses of the eastern portion of the basin, and together with the shorter water columns, seasonal insolation is very effective in warming, producing temperaures up to 1 2°C in the upper layer (in contrast with maxima of ~8°C in the Gulf of Anadyr). The coldest, most saline water is water of the Anadyr Current entering through the Strait of Anadyr (see above), and also shelf water from south of St. Lawrence Island (cold, relatively saline shelf water is probably also entering the basin around the eastern end of St. Lawrence, through the west side of Shpanberg Strait, but the A^o/'o/ev data do not cover Shpanberg Strait). To illustrate quantitatively the modifications occurring in the basin. Fig. 3b plots key stations. There is a salinity gradient of more than one-half ppt across Anadyr Strait. The most saline water is from the Anadyr Current (Station 39. cf. Fig. 2b). On the east side (Stations 42, 43), though, the waters are both less saline and colder — this is shelfwaterfrom south of St. Lawrence Island, which is originally Bering Slope water that has been in residence on the huge shelf south of St. Lawrence where it has become diluted to a small degree by a freshwater admixture from the Alaskan Coastal water (see Coachman & Shigaev. Subchapter2.1. this volume) and further modified in winter by products from freezing activity in the perennial polynya south of St. Lawrence ( Schumacher el al. . 1983). This is the origin 5- VBERING STRAIT (FAST) 179 CHIRIKOV BASIN UJ 3 cr z> I— < (r UJ Q. 2 2 SOUTHWEST OF NOME BERING STRAIT ^(WEST) 76;' 31 32 33 SALINITY Fig. 3b. T/S diagram of key stations from the Chirikov basin, illustrating the major water mass modifications therein. No change in salinity of the water on the western side indicates no lateral mixing; only deeper temperatures are raised through vertical mi.xing. On the east, small lateral as well as vertical mixing makes Alaskan Coastal water less saline, warmer, and a little less dense. also of the "cold center" water. The flow through the eastern part of Anadyr Strait is of this shelf water mass, not pure Anadyr water, giving rise to the cross-strait gradient in salinity. The three stations across the western channel of Bering Strait, Stations 76 on the west to 78 near large Diomede Island, illustrate the characteristics ofthese water masses after transiting Chirikov basin. The cross-strait salinity gradient is precisely the same as in Anadyr Strait, only the waters have wanned — minimum temperatures are now about 1.5°C instead of <0°C. We can interpret that modification of the water masses flowing northward through the middle and western part of the basin includes no significant lateral mixing — there is no evidence of any interaction between adjacent water masses within the flow, nor any reduction in salinities by admixtures of Siberian Coastal runoff on the west or fresher Alaskan Coastal water on the east. The only significant mixing is vertically in the water columns, which by mixing down warmer surface water has raised bottom temperatures by ~\°C. Alaskan Coastal water on the east side of the basin, not as well covered by Korolev data, is illustrated by Station 102 taken about halfway between Nome and St. Lawrence Island (see Fig. 1 ). This water is the warmest and least saline of the water masses, and the closer to the Alaskan coast, the warmer 31 US/USSR BERING '88 CHUKCHI/BERING STRAI" CHUKCHI 10 /- 5 30 31 32 SALINITY (ppt) Fig. 4a. All CTDdata(l-m average values) from Bering Strait and southern Chukchi Sea. and fresher it becomes; this accounts for the trend of data points in Fig. 4a from about 3°C. 32 ppt. toward 12°C, 30 ppt. The flow is northward parallehng the coast, then through the eastern channel of Bering Strait, where its characteristics are illustrated by Station 79. Thus, the modification of the waters on the eastern side of the basin involves both lateral and vertical mixing. Salinities are reduced by about 1 ppt in transit through admixing with fresher waters closer to shore, ultimately of course due to substantial coastal runoff As temperatures are in general higher in the shallower waters near shore, the lateral mixing also gives rise to some warming. Water temperatures are also increased through vertical mixing, as with the waters on the western side, and undoubtably the warming is more effective in the shallower waters of the eastern side. Between the two effects, T increases are of the order of 3°C. We note that the mixing processes on the eastern side are diapycnal, leading to decreases in water densities, which is not true of the modifications in the west. The reason for this is the difference in effects of salinity and temperature on density, salinity is much more important in "controlling"" density in cold water (cf slopes of isopycnals in Fig. 2b). Chukchi Sea All CTD data from the Chukchi Sea are plotted in Fig. 4a. Similarly to the Chirikov basin, there is a concentration of bottom values in the salinity range -32.2 to 32.9 ppt, but the temperatures of this water are slightly warmer than to the south, ranging from ~ 1 .5 to 4°C. From this concentration, data points extend in two directions. One trend is toward warmer and fresher, toward ~10°C and 30 ppt, much like the trend in the Chirikov basin data (cf. Fig. 3a). These data are from the water masses that have entered the Chukchi Sea from the south, through the Bering Strait; salinities have not been modified appreciably since transiting Bering Strait, but the small warming indicates that heat continues to be added to the bottom water through vertical mixing. WEST OF PT HOPE 49\-\48 SALINITY Fig. 4b. As with Figs. 2b, .^b, but illustrating the major water mass modifications occurring in the southern Chukchi Sea. The later and vertical mixing processes found in the eastern part of the Chirikov basin continue to modify the water masses How ing northward through Kotzebue Sound and passed Pt.Hope. A colder, more saline water mass indigenous to the Chukchi Sea is advected southeast by the Siberian Coastal Current, then circulates cyclonically and mixes with the water flowing north through Bering Strait. The other trend is toward a colder and more saline water type, -33.5 ppt and 0°C. This is water that appears nowhere south of the Bering Strait, so must be indigenous to the Chukchi Sea. The only water south of Bering Strait with S>33 ppt is in the Gulf of Anadyr and was not observed north of Anadyr Strait, which positively rules out the northern Bering Sea as a possible source for this relatively cold, high salinity water. Key stations illustrating the water masses in the southern Chukchi Sea are plotted in Fig. 4b. The current flowing northward through Bering Strait trends eastward into Kotzebue Sound, then tuins north and west and Hows passed Pt. Hope into the northern Chukchi Sea (cf. Coachman ct al., 1975, Chap. 4). The core of flow of this water, that with the highest salinities, is water transitting the western channel of Bering Strait (Stations 76-78; cf Fig. 3b). This water is observed west of Pt. Hope at Stations 48 and 49. The water east of this core tlow. between it and the Alaska coast (represented west of Pt. Hope by Station 50), is all less saline and warmer, and creates the data trend exposed in Fig. 4a. In traversing Kotzebue Sound (a distance of -350 to 400 km) salinities of the core water have been reduced a little, about 0.2 to 0.3 ppt, and bottom temperatures have been increased a further 0.5°C. Thus, both vertical mixing and a small amount of lateral 32 mixing, as obtained throughout the eastern part ol Chirikov hasin, eontinues to modify these water masses from the south as they traverse the southern Chukehi Sea. The relatively eold. sahne water that is not eoming from the south is found in the eentrai and western parts of the southern Chukehi Sea; in the Korolcv data the extreme \ alues are from Stations 44 and 45, north of Koi\ uehin Bay on the Siberian Coast (cf. Frontispiece). Current measurements (Coachman & Shigaev. Subchapter 2. 1 . this \c)lume) indicated this water was (lowing southeast, parallel with the Siberian coast, the so-called Siberian Coa,stal Current, This current is advecting the cold, high S water into the southern Chukehi Sea from somewhere in the northwest, perhaps near Long Strait (between Wrangel Island and the mainland). The flow did not, however, continue southeast as far as Bering Strait; no water with S>32.9 ppt was observed there. Thus, the Siberian Coastal Current separates from the coast before reaching Bering Strait, and curves eastward into the central part of the southern Chukchi Sea. Waters in the middle of the region, midway between Alaska and Siberia (Stations 47, 56). indicate considerable mixing has taken place between this cold, saline water, and the core water of the northward flow from Bering Strait that lies around the east and north sides of the central region. The interaction has reduced salinities of the Siberian Coastal water in the central region to ~.^3 ppt and warmed the mass by I to 2°C. We note the situation in August 1988 is undoubtedly the normal summer tlow pattern; however, under rare conditions it appears that the Siberian Coastal Current can penetrate farther southeast, as far as Bering Strait. Ratmanov (1937a) observed cold, saline water near Cape Dezhneva in summer 1933. but it was not moving southward through the strait. There is no evidence that this water ever penetrates into the Chiriko\ basin. Summary of Modifications The quantitative changes in temperature and salinity characteristics of the water masses as observed in August 1 988 are summarized in Table I . The changes are in characteristics of the water layers below the surface layer, which are conservative ( i.e., T and S values are altered by the processes of advection and diffusion only). The surface layer properties are affected also by surface exchange; in summer they are warmer and less saline than the deeper waters and much more variable. Table I shows, in addition to the approximate T and S change, the estimated distance over which the change has taken place and the property value change per km. The latter statistic gives an idea of the effectiveness of the mixing in that part of the regime; comments list the major processes acting. The greatest changes in water mass properties take place at the beginning, where the Bering Slope Current water crosses the outer shelf on its way into the Gulf of Anadyr. Layering of cold, less saline shelf water with warmer, more saline slope water, followed by vertical mixing, are effective in reducing S"s andT'sand. ultimately, creating the quite uniform Anadyr water mass, which is advected on northward through Bering Strait. The energy for the mixing is from shear in the Anadyr Current, generated both laterally as the current circumnavigates the gulf and vertically in the shoaling water columns. Across the Chirikov basin the major mixing is vertical; this process is stronger on the east side in the shallower water. Lateral mixing is small; there is essentially none in the west. and it is small in the east, leading to small reductions in S of the coastal water. These same processes continue to modify Anadyr/Bering Shelf and Alaskan Coastal waters in the southern Chukchi Sea at about the same rate. Siberian Coastal water, indigenous to the Chukchi Sea, enters the southern part of the sea from the northwest, and then apparently circulates in acyclonic gyre, interacting with Anadyr water around its east and north sides. The interaction seems moderately active and analagous with that in the Gulf of Anadyr; first a layering and interleaving of the water masses (densities differ by -0.5 st). followed by vertical mixing. We aeknowledge the helpof Margaret Lavender both in the field and in data reduction. Captain O. A. Rostovstev and Chief Scientist. Professor A. V. Tsyban. deserve special thanks, as does all the crew of the Korotev. Viktor Shigaev was a great help in liaison and interpretation, and the skill of hydrographic specialists Sergei and Anatoly was much appreciated. The senior author is indebted to Dr. R. S. Jones for allowing his participation in the cruise and for use of the L'TMSl equipment aboard the Konilcv. This is Contribution No. 777 of the Marine Science Institute. University of Texas. 33 TABLE 1 Water Mass Property Modifications (Summer). Change per km (xK)') km AS(ppt) AT(C) T S Comments Gulf of Anadyr Bering Slope Cur. to C. Navarin 150 -0.4 -1.5 2.7 10.0 lateral & vertical mix. with shelf water C. Navarin to mid-Gulf 250 -0.3 -.05 1.2 2.0 layering; small vertical mixing mid-Gulf to Str. of Anadyr 250 -0.2 +0.5 0.8 2.0 vertical mixing (homo- 500 -1-0.6 -t-2.0 1.2 4.0 genization) layering, then vert. mix. "cold core" Water in Anadyr curr. Chirikov basin Anadyr to Bering Strait 280 0.0 -1-1.5 0.0 5.4 vertical mixing Alaskan Coastal 180 -0.6 -1-2.5 3.3 14.0 strong vertical mix; lateral mix. with runoff Chukchi Sea Anadyr/Bering Shelf to Pt. Hope 380 -0.2 -^0.5 0.5 1.3 vertical mix.; small lateral mix. with runoff Siberian Coastal to mid-basin 220 -0.2 + 1.5 0.9 6.8 lateral mix. with Anadyr; vertical mixing 34 Chapter 2 References Aagaard. K., Coachman, L. K. & Carmack. E. C. ( 198 1 ). On the halochne of the Arctic Ocean. Deep-Sea Res. 28. 529-545. Aagaard. K.. Roach. A. T. & Schumacher. J. D. ( 1 985 ). On the wind-driven variabiHty of the flow through Bering Strait. / Geophys. Res. 90. 7213-7221. Amos. A. F. AkudemikKorolev(A¥.-M-Vil)C'\D&did: Standard level listings. Univ. Te.x. Mar. Sci. Piihl. TR/9()-00i. Barnes. C. A. & Thompson. T. G. (1938). Physical and chemical investigations in the Bering Sea and portions of the North Pacific Ocean. Univ. Wasli. Pithl ()cean<>i;r. 3(2), 35-79. Coachman. L. K. (1986). Circulation, water masses, and fluxes on the southeastern Bering Sea Shelf Com. Shelf Re.s. 5(1/2), 23-108. Coachman, L. K. & Aagaard, K. ( 1988). Transports through Bering Strait: Annual and interannual variability. J. Geophy.s. /?es. 93, 15535-15539. Coachman, L. K., Aagaard. K. & Tripp. R. B. ( 1975). Bering^ Slrail: The Regional Physical Oceanography. Univ. Washington Press. Seattle. 172 pp. Deleersni jder. E. & Nihoul, J. C. J. ( 1 988). General circulation in the northern Bering Sea. ISHTAR Annual Progress Report, 392 pp. Faculty of Fisheries ( 1974). Data Record of Oceanographic Observations and Exploratory Fishing 17, Faculty of Fisheries, Hokkaido University, Hakodate, 294 pp. Grebmeier, J. M.. Cooper, L. W. & DeNiro, M. J. (1990). Oxygen isotope composition of bottom seawater and tunicate cellulose used as water mass indicators in the northern Bering and Chukchi Seas. Lininol.Oceauogr. 35(5). 1182-1195. Kinder. T. H.. Chapman. D. C. & Whitehead. J. A.. Jr. ( 1986). Westward intensification of the mean circulation on the Bering Sea Shelf. J. Phys. Oceanogr. 16. 1217-1229. Kinder, T. H., Coachman, L. K. & Gait, J. A. ( 1975). The Bering Slope Current system. J. Phys. Oceanogr. 5. 231-244. Mountain. D. G.. Coachman, L. K. & Aagaard, K. (1976). On the How through Barrow Canyon. / Phys. Oceanogr. 6, 461-470. Muench, R. D, Tripp, R. B. & Cline, J. D. ( 198 1 ). Circulation and hydrography of Norton Sound. In The Eastern Bering Sea Shelf: Oceanography and Resources. Vol. 1, Chap. 6, pp. 77-93. Office of Marine Pollution Assessment, NOAA, US Department of the Interior. Washington, D.C. Nihoul, J. C. J.. Deleersni jder. E. & Djenidi. S. ( 1990). Modeling thegeneralcirculationof shelf seas by 3D- models. Earth- Sci.Rev. 26, 163-189. Ratmanov. G. E. (1937a). On the hydrology of the Bering and Chukchi Seas. In Investigations of the Seas of the USSR 25, 10-118. (in Russian) Ratmanov, G. E. ( 1937b). On the question of water exchange through Bering Strait. In Investigations of the Seas of the USSR 25, 119-135. (in Russian) Schumacher, J. D.. Aagaard, K., Pease. C. H. & Tripp. R. B. (1983). Effects of a shelf polynya on flow and water properties in the northern Bering Sea. J. Geophys. Res. 88, 2723-2732. Springer, A. M., McRoy, C. P. & Whitledge, T. E, (in press). The paradox of pelagic food webs in the northern Bering Sea. III. Patterns of primary production. Cont. Shelf Res. Stigebrandt, A. (1984). The North Pacific: A global-scale estuary. / Phy.^i. Oceanogr. 14, 464-470. Sverdrup, H.U. (1929). The waters on the north Siberian shelf. The Norwegian North Polar Expedition with the "Maud", 1918-1925. Scientific Results, l\, {2). 13\ Bergen. US Coast Guard Oceanographic Unit ( 1964). Oceanographic cruise USCGC Northwind Bering & Chukchi Seas July- September 1962. US Coast Guard Oceanographic Report 1, 104 pp. US Coast Guard Oceanographic Unit (1965). Oceanographic cruise USCGC Mw/Zniv/K/Chukchi, East Siberian, and Laptev Seas J uly-September 1963. US Coast Guard Oceanographic Report 6, 69 pp. Walsh, J. J., McRoy, C. P., Coachman. L. K.. Goering. J. J., Nihoul. J. C. J.. Whitledge, T. E.. Blackburn. T. H.. Parker, P. L.. Wirick. C. D., Shuert. P. G.. Grebmeier. J. M.. Springer. A. M.. Tripp, R. B., Hansell, D. A., Djenidi. S., Deleersnijder, E., Henriksen, K., Lund, B. A., Andersen, P., MuUer-Karger. F. E. & Dean. K. (1989). Carbon and nitrogen cycling within the Bering/Chukchi Seas: Source regions for organic matter effecting AOU demands of the Arctic Ocean. Prog. Oceanogr. 22(4). 277-359. 35 Chapter 3: HYDROCHEMISTRY Editors: SERGEI M. CHERNYAK & TERRY E. WHITLEDGE 3.1 Biogenic Nutrient Content TERRY E. WHITLEDGE' , MIKHAIL 1. GORELKIN^ , and SERGEI M. CHERNYAK* "Marine Science Institute. University of Texas at Austin. Port Aransas. Texas. USA 'Institute of Global Climate and Ecoloi;\. State Committee for Hydrometeoroloi^y and Academy of Sciences. Moscow. USSR Introduction The early investigation of the biogenic nutrient content of Bering Sea waters have shown these elements that are necessary for phytoplunkton grow ih lo often be present in surface waters in quite high concentrations (Barnes & Thompson, 1938). More recently, the Processes and Resources of the Bering Sea Shelf (PROBES) program did an exhaustive study of the physical-biological ecosystem dynamics of the southeastern Bering Sea Shelf. Over a five-year period, the nutrient content across the shelf was observed to be related to three frontal systems that governed the nutrient dynamics in the open ocean, outer shelf, middle shelf, and inner shelf (Coachman, 1986; WhitledgC(Vu/., 1986). The later program of Inner Shelf Transfer and Recycling (ISHTAR) further investigated the transport of water and nutrients through the northern Bering Sea into the Chukchi Sea and studied the primary production/decomposition processes that occurred in the Alaskan Coastal water, Bering Shelf water and Anadyr water (Walsh et al.. 1990). The Third Joint US- USSR Bermg & Chukchi Seas Expedition in 1988 was a tremendous enhancement to the ISHTAR sampling program, which had previously lacked a complete and quasi-synoptic sampling of all of the above water masses. The biogenic nutrient content is indicative of the potential primary production that ma\ occur in seawater and therefore is used to assess one ol the major factors controlling primary food production in the marine environment. The concentration of nitrogen, in the form of nitrate and ammonium, is particularly useful because most oceanic environments contain small concentrations of nitrogen relative to phosphorus and silicon and is often thought lo limit rales of primary production (Ryther & Dunstan, 1971 ). The uptake of biogenic nutrients along with carbon dioxide and light is important as fuel for primary production processes. The production of nutrients by regenerative processes must also be considered because the nutrients present in seawater are replenished on a continuous or periodic basis. These regeneration processes maintain the long-term primary production of an ecosystem especially on continental shelves where benthic regeneration also contributes nutrients to the euphotic zone. The biogenic nutrient content of water in the Bering and Chukchi Seas in general is high, reflecting its origin in the North Pacific Ocean. The deep Bering Sea, where few biological measurements have been taken, maintains high nutrient concentrations throughout the year, and plant biomass represented by chlorophyll is small. The continental shelf, which comprises about 45% of the area of the Bering Sea, varies from high to low nutrient concentrations as the annual cycle of primary production occurs (Whitledge etui, 1986). The primary purpose of this paper is to describe the nutrient, oxygen, and pH variations of the south and east regions of the deep Bering Sea, the northern Bering Sea Shelf and the southern Chukchi Sea ( Frontispiece). All of these areas were sampled on the Third Joint US-USSR Bering & Chukchi Seas Expedition in 1 988 as a part of a program to investigate the ecology and health of the Bering and Chukchi Seas. Methods Water samples were collected on the upcast with a Sea- Bird CTD/rosette sampler. Water samples were immediately collected in polyethylene scintillation vials and were analyzed on a model 300 Alpkem segmented flow analyzer at 80 samples per hour. The analytical techniques were adapted to small volume glassware from previously described methods (Whitledge et al.. 1981 ). The basic analytical methods were described by Armstrong et al. (1967) for nitrate, phosphate, and silicate. Ammonium was measured by the phenohypochlorile method of Koroleff (1970) as adapted to a continuous analyzer by Slawyk and Maclsaac (1972) and modified by Patton and Crouch (1977). Standard Winkler titrations were used to determine the concentration of dissolved oxygen. Results Northern Shelf Regions The physical transport of water from the North Pacific inio the deep Bering Sea moves eastward and north in a counter- clockwise gyre until it nears the coastline of the Soviet Union where it bifurcates and a northern segment Hows through the Gulf of Anadyr toward Bering Strait (Whitledge et al.. 1988). This long-term net movement of water carries a large quantity of biogenic nutrients from the deep Bering Sea onto the shallow northern shelf of the Bering and Chukchi Seas where primary production processes consume them. The northern tlow of water varies from about 0.5 to 1.0 Sv and produces bathymetrically induced upwelling as a result of the 30-50 m water depths of the shelf. 39 The temperature and salinity distribution clearly define the general circulation patterns between the Gulfof Anadyr and the southern Chukchi Sea. The differential between surface and bottom water was as large as 8.5°C and 1.5 "/„,, salinity in the Gulf of Anadyr ( Fig. 1 A,B ) but decreased to less than 1 °C and 0.5 "/,,,) in Chirikov basin after passing through Anadyr Strait. The low salinity (Fig. 1C,D) Alaskan Coastal waters and Bering Shelf waters maintain theireastem positions and reduced salinities throughout northward transport (Coachman & Shigaev, Subchapter 2.1, this volume). The relatively low temperature bottom water denoted by the -1.5°C isotherm delineates the cold high-salinity water formed during the previous winter months by production of ice. The presence of this cold water indicates the slow circulation velocities on the eastern Bering Sea Shelf. Accumulation of benthic regeneration products can occur in these waters. The nitrate content of the surface water (Fig. 2A) displays a pattern of reduced concentrations where the waters are stratified in the Gulf of Anadyr and Chukchi Sea. The largest surface concentrations of nitrate occur in the Chirikov basin after upwelling and mixing in Anadyr Strait, especially on the west side along the Soviet coastline, and extend into the southern Chukchi Sea. These very large surface concentrations support the high primary production rates reported in the Bering Strait region (Sambrotto et al.. 1984). Near bottom nitrate concentrations (Fig. 2B) originating in the deep Bering Sea provide a substantial part of the nitrogen to feed primary production processes. The nitrate values larger than 30 |imole/l are quite unusual for a shallow shelf region; even coastal upwelling regions seldom have greater than 1 5-20 fimole/l inside the shelf break. Concentrations of near bottom nitrate above 30 |imole/l disappear at Anadyr Strait 180 175 170 165 180 175 170 165 180 175 170 165 Fig. 1. The Mirlace (A) and bottom (B) distribution of temperatures (°C), surface (C) and bottom (D) distribution of salinity ("/„, ) measured in the northern Bering and Chukchi Seas. 40 probably as the result of strong vertical mixing; however, values larger than 20 |imole/l were observed on the west side of all three regions (Gulf of Anadyr, Chirikov basin, Chukchi Sea). The presence of these large near-bottom nitrate concentrations are almost certainly due to some nitrification (ammonium conversion to nitrate by bacteria) occurring in the Chirikov basin and Chukchi Sea. Ammonium, the regenerated form of nitrogen, was found to have very low concentrations (Fig. 2C) in surface waters. The very high affinity of phytoplankton to ammonium reduces concentrations to very low levels unless unusually large surface ammonium regeneration rates are occurring. The bottom ammonium concentrations (Fig. 2D ) reflect the active nature of nutrient regeneration in the near bottom waters and sediments. Decomposition of organic matter releases large amounts of ammonium especially where high priinary production/deposition is occurring. This process is best shown in the central Chukchi Sea and to a smaller extent in the western Chirikov basin. Remember that the east side of the Bering and Chukchi Seas has very small organic production rates compared to the western portions. The highest near bottom ammonium concentrations were found in the low temperature "winter water" in the Gulf of Anadyr and along the Soviet coast in the Chukchi Sea. These large ammonium concentrations reflect the accumulation that occurred over the several months since the cold water was produced. In both cases more than 4 (iniole/1 concentrations were observed in the two regions. The Gulf of Anadyr ammonium probably contributes to the surface increases of ammonium that are observed downstream after vertical mixing in Anadyr Strait. 180 175 170 165 ==V -+- -+- 180 175 170 165 180 175 170 165 Fig. 2. The surface (A) and bottom (Bl distribution of nitrate ()i mole/1), the surface (C) and bottom (D) distribution of ammonium ((J mole/1) measured in the northern Bering and Chukchi Seas. 41 The surface silicate concentrations (Fig. 3 A) are similar to those of nitrate, especially the strong east-west gradient in the Chirikov basin. Silicate is mainly utilized by diatom populations but other phytoplankton may also have a silicate requirement. Even the areas where high silicate concentrations have been reported in river discharge contained less than 5 |imole/l. Near- bottom silicate concentrations (Fig. 3B) reflect the large concentrations present in deep Bering Sea water with values above 50 [imole/l. Vertical mixing in Anadyr Strait and subsequent uptake by phytoplankton reduce concentrations to the range of 10-30 |imole/l. The east side of the ecosystem all had values less than 10 |imole/l. The surface phosphate concentrations (Fig. 3C) were adequate to support primary production processes throughout the area of investigation. Areas with phosphate concentrations less than 0.5 |imole/l also contained small amounts of nitrate and silicate; therefore, phosphate was always in plentiful supply compared to other nutrient forms. Near-bottom phosphate concentrations ( Fig. 3D) reflect both the enrichment from the deep Bering Sea into the Gulf of Anadyr and the cumulative effects of phosphate regeneration in the Chirikov basin and Chukchi Sea. The Gulf of Anadyr serves as the conduit for flow of water from the deep Bering Sea into the confined Chirikov basin. The center of the Gulf of Anadyr is stratified with the warmer surface waters depleted of nutrients ( Fig. 4), but near the coast, all isopleths rise toward the surface, indicative of active coastal upwelling. Surface concentrations of all nutrients were low enough to reduce primary production. The highest chlorophyll measured in this region (24-28 |ig/l) was on Station 26 at a 180 175 170 165 180 175 170 165 180 175 170 165 180 175 170 165 Fig. .^. The surface (A) and boltcim (Bl dislrihulion ol silicate (n mole/1), the surface (C) and hcitlcim (D) distribution of phosphate (|i mole/I) measured in the northern Bering and Chukchi Seas. 42 depth of 20-25 m. which coincides with the upwelling area, but the phytopianivton population was so great that nitrate, silicate, ammonium, and phosphate were reduced to 10.3, 1.2. 0.1. and 1 .4 |.imole/l respectively. The outer end of this transect was located in the near-hottom winter shelf water as indicated by the ammonium signature (Fig. 4B). The Chirikov basin receives water from the Gulf of Anadyr after nearly complete vertical mixing occurs throughout the water column in Anadyr Strait (Fig. 5). The very uniform vertical nutrient concentrations on the western end of the transect changes into a stratified system near the middle where Bering Shelf waters and Alaskan Coastal waters are encountered. The strong east-west gradients are the products of the lack of flow from the deep Bering Sea and the little vertical mixing in Shpanberg Strait on the east side of St. Lawrence Island. The Chukchi Sea receives the waters that flow through Bering Strait after passing through Chirikov basin ( Fig. 6 ). The nutrient content of this northward (lowing water has been reduced somewhat in the Chirikov basin, but the major portion remains to support primary production in the Chukchi Sea. The strong east to west gradient of nutrients remains similar to the more southern areas. The Chukchi transect of stations shows the large near surface concentrations of nutrients which corresponds to observations of the largest chlorophyll concentrations. Nitrate, ammonium, and phosphate concentrations show enhancement near the Soviet coast, which probably results from a southward tlowing Siberian Coastal Current (Coachman & Shigaev, Subchapter 2. 1 . this volume). The Alaskan Coastal water displays a low nutrient content consistent with more southern transects except silicate, which is enriched by about l()|imole/l. Even though past observations have shown all nitrogen in the Yukon River was removed quickly in the Chirikov basin, this nearshore increase in silicate may be related to the Yukon River. This would be consistent with the distribution of carbon isotope and C/N ratios as reported by Scalan et al. (Subchapter 8.5.1, this volume). The temperature-salinity diagram for all samples collected on the 1988 joint cruise (Fig. 7A) shows the very cold water below 0°C that falls into the salinity range of 32-32.7 7,k, . The low temperature water between 0 and 0.5°C has a salinity of 33-33. 5"/|,„ so this must represent water that was formed during ice production, which increases the salinity. The nitrate-salinity diagram for all samples (Fig. 7B) on the joint expedition fell predominantly in the salinity range of 32-32.5"/,,,. and the nitrate varied from about 0.1 to about 40 |ig-at/] . A few points deviated from this general distribution in low salinity water in the Alaskan Coastal Current that was depleted of nitrate and higher salinity samples from the deep Bering Sea where nitrate concentrations exceeded 50 ^g-at/l. STATION NO STATION NO 75 A ^ Vso V 100 200 DISTANCE (Km) 300 400 100 DISTANCE (Km) Fig. 4. The distribution of nitrate (A), ammonium (B), silicate (C) and phosphate (D) in a transect of stations across the Gulf of Anadyr. Units are H mole/1. 43 STATION NO STATION NO. 10 20 30 40 50 A 1 5 I 1 1 1 ^ I.I. \ S / L ^^^,.^ B 1 . 1 . 1 . 1 . 1 00 1 50 DISTANCE (Km) 100 150 DISTANCE (Km) 250 Fig. S. The di.slribution ot nitrate (A), uninionium (B), silieate (C) and phosphate (D) in a transect of stations across the Chirikov basin. Units are Jl mole/1. 3^^^^'°^^° STATION NO C7) o CD to CM (D s (D CD ^ 1 \ 1 l< 2 n ■> -- \ B 1 1 I 1 1 1 1 100 150 200 250 DISTANCE (Km) 350 100 150 200 250 DISTANCE (Km) Fig. 6. The distribution of nitrate (A), aninionium (B). silicate (C) and phosphate (D) in a transect of stations across Chukchi Sea. Units are |i mole/1. 44 I SAUNfTY (o/oo) Fig. 7. (A) Temperature ('€) and salinity ("/,„); (B) nitrate (n g-at/1) and salinity (7(x,) plot for all stations sampled in the Bering and Chukchi Seas. SAijNrrr (o/oo) Fig. 8. (A) Silicate (|i g-at/l) and salinity (7i„) plot; (B) phosphate (|i g-at/1) and salinity ("/„,) plot for all stations sampled in the Bering and Chukchi Seas. The silicate-salinity diagram for all samples (Fig. 8A) shows the range of silicate to be between 0.5 and 60 |ag-at/l for most samples between 3 1 and 33 "/„„. The low salinity Alaskan Coastal water had values below 20 |ag-at/l and the deep Bering Sea contained concentrations above 230 |ag-at/l. In contrast, the range of phosphate concentrations (Fig. 8B) was 0.23 to about 3.5 ug-at/1. The uniform distribution of phosphate compared to nitrate is probably due to the rapid regeneration of phosphate in the water column. Deep Bering Sea The South and East Polygons in the Bering Sea had stations with depths approaching 4,000 m. The vertical profiles of nitrate and silicate (Fig. 9B) provide some insight into the nutrient gradients in the deep Bering Sea. The concentrations of nitrate and silicate were very similar in the upper 100 m between the two polygon locations; however, the East Polygon had larger nitrate and smaller silicate concentrations compared to the South Polygon. The resulting plot of nitrate/silicate ratio with depth (Fig. 9A) clearly shows the differences. The low oxygen concentrations present in the South Polygon (Fig. 1 1 A) are more conducive to denitrification process, so it is likely that the nitrate has been lost from the deep water by this process. The near-bottom waters near the South Polygon had previously been observed to contain a layer of slightly less saline water near the bottom (Park et ai. 1975). The very distinct vertical distributions make further sampling in these regions a necessity. The vertical phosphate distributions in the deep Bering Sea (Fig. lOB) also tend to be elevated in the East Polygon compared to the South with values greater than 3 |imole/l. The dissolved inorganic nitrogen (DIN)/phosphate ratio showed that most deep ocean values were at or above 16:1. especially in near-bottom water where the ratios were >20: 1 . The vertical distributions of pH (Fig. 1 IB) and dissolved oxygen (Fig. 1 1 A ) in the deep Bering Sea reflect the relatively high rates of primary production in the surface waters and the slow rate of water circulation at depth. These distributions result from the consumption of dissolved oxygen and the respiratory release of carbon dioxide as particulate matter sinks into the deep sea. Since these parameters are both closely associated with the decomposition of organic matter it is not unusual for their relationships with salinity to be similar (Figs. 12A.B). The highest salinity waters in the deep Bering Sea have increased values of both pH and dissolved oxygen and may be related to bottom water renewal processes from the North Pacific Ocean. 45 s 1988 US-USSR CRUISE OOP BEWHO STATIONS (Tliousands) DEPTH (m) Fig. 9. The vertical distribution of (A) nitrate and silicate (|J mole/1) and (B) the nitrate/silicate ratio for all stations during the joint expedition. Discussion The biogenic nutiient content of the Bering Sea is closely coupled to the primary production and regeneration process occurring within its waters. The deep Bering Sea at South and East Polygons have a continued supply of nitrate, silicate, and phosphate to support primary production processes, but a phytoplankton bloom with large chlorophyll concentrations has not been observed. The high nutrients and low chlorophyll are similar to the situation observed in the North Pacific Ocean at Station P. The waters at depth in the deep Bering Sea hold large quantities of nutrients compared to other parts of the worid"s oceans, which indicates that the Bering Sea is a sink rather than a source. This fact is also true for constituents other than nutrients since there is no apparent ventilation of the deep waters. Future work in the deep Bering Sea should focus on the inputs to the deep water, its age and its level of anthropogenic contamination. The Gulf of Anadyr receives deep waters from the open Bering Sea and transmits these waters to Anadyr Strait, which separates St. Lawrence Island from the Soviet mainland. The waters in the Gulf of Anadyr are productive, especially near the coastline where upwelling occurs. The resulting phytoplankton Fig. 10. The vertical distribution of (A) the dissolved inorganic nitrogen/ phosphate ratio and ( B ) phosphate ((i mole/1) for all stations dunng the joint expedition. probably act as a seed population for the upwelled water in Anadyr Strait and provide organic matter to support regenerative processes. Note that this nutrient regeneration occurs in the deposition areas depicted by Coachman and Shigaev ( Subchapter 2. 1 . this volume). The bottom water in the central Gulf of Anadyr has the signature of winter water with its extremely cold temperatures of <0.5°C. These waters slowly transit through Anadyr Strait while being mixed with open Bering Sea waters. The Chirikov basin acts as the "chemostat" in the ecosystem by supplying large quantities of nutrients as inflows to ultimately produce organic matter. The transit time through the Chirikov basin may be so sinall that not all nutrients are utilized, similar to a wash-out condition. The northward transport also includes inner shelf water from the southeast Bering Sea that often produces a separate phytoplankton bloom in the middle of Chirikov basin (Hansell et al.. 1989). The majority of organic matter and remaining nutrients advect northwiu'd along the western edge into the Chukchi Sea (Hansell & Goering. submitted). The Chukchi Sea receives the northward tlow of nutrients and organic matter and further primary production occurs in the central portion where surt'ace concentrations of nitrate are 46 greater than 1 |imole/l (Fig. 2A). The organic matter then suhstantiaily falls to the bottom to fuel further processes and contributes to the high organic content of the sediments ( Walsh etal.. 1989). The e.xtended sur\ey during the 19S8 joint expedition encountered an additional source of high-salinity, high-nutrient water near Kolyuchin Bay. The high nitrate content of the southward tlowing coastal water (Coachman & Shigaev, Subchapter 2. 1 , this volume ) indicates that additional nitrogen is added to the central Chukchi Sea as it joins the Bering Strait water. There is some speculation about the original source of this southward tlowing water but oxygen- 1 8 data indicates that it may have been winter water that previously had passed through Bering Strait (Grebmeier <'/«/.. 1990). The importance of this additional nutrient input to the central Chukchi Sea is great because it could supply an additional amount of nutrients to enhance the annual primary production rates. The gains and losses of the Chukchi Sea are very poorly known but there is some speculation that nutrients utilized here transit to the deep ocean arctic basin. We would like to acknowledge D. Viedt for technical help in the collection ot field samples and its chemical analysis. We would also like to thank Dr. L. K. Coachman and the other US scientists aboard the research vessel {WM ) Akademik Korolev. Finally, a special thanks is given to all the Soviet scientists and especially Professor A. V. Tsyban and Captain O. A. Rostovtsev of the R/V Akademik Korolev. This project was part of the Third Joint US-USSR Bering & Chukchi Seas Expedition aboard the Soviet R/V AA«(/em;A- AV»o/e\'. We express appreciation to the US Fish and Wildlife Service, USA, and the State Committee for Hydrometeorology, USSR, who made our participation possible. This research was mainly supported by Grant No. DPP86()56.'i9 from the Division of Polar Programs of the National Science Foundation as part of the ISHTAR program. Contribution No. 766 of the Marine Science Institute. University of Texas at Austin. 0 500 1000 1500 2000 2500 3000 3500 Dapth (m) 12 10 E 8- i 6 o 32 33 34 Salinity (o/oo) 35 500 1000 1500 2000 2500 3000 3500 Depth (m) 32 33 34 Salinity (o/oo) Fig. 1 1. The vertical distribution of (A) dissolved oxygen (mg/1) and (B) pH for the deep Bering Sea stations. Fig. 12. (Al dissolved oxygen (mg/1) and salinity ["1^ ) plot (B) pH and salinity ("/„,) plot for the deep Bering Sea stations. 47 48 Chapter 3 References Armstrong. F. A. J.. Stems. C. R. & Strickland, J. D. H. ( 1 967). The measurement of upwelling and subsequent biological processes by means of the Technician Auto Analyzer and associated equipment. Deep Sea Re.\. 14. .^81-389. Barnes. C. A. & Thompson, T. G. (1938). Physical and chemical investigations in the Bering Sea and portions of the North Pacific Ocean. In University of Washington Publications in Oceanography, Vol. 3, pp. 35-79. Coachman, L. K. ( 1986). Circulation, water masses and fluxes on the southeastern Bering Sea Shelf. Cont. Shelf Res. 5, 23-108. Coachman, L. K, & Shigaev, V. V. ( 1992). Northern Benng- Chukchi Sea ecosystem:The physical basis. (Subchapter 2.1, this volume). Hansen, D. A. & Goering. J. J. (submitted). Pelagic nitrogen flux in the northern Bering Sea. Cont. Shelf Res. Hansen, D. A., Goering, J. J., Walsh, J. J., McRoy, C. P.. Coachman, L. K,, & Whitledge, T. E. (1989). Summer phytoplanklon production and transport along the shelf break in the Benng Sea. Cont. Shelf Res. 9, 1083-1 104. Grebmeier, J. M., Cooper, L. W. & DeNiro, M. J. (1990). Oxygen isotope composition of bottom seawater and tunicate cellulose used as water mass indicators in the northern Bering and Chukchi Seas. Limnol. Oceanogr. 35, 1178-1191. Koroleff, F. (1970). Direct determination of ammonium in natural waters as indophenol blue. Information on techniques and methods for seawater analysis, luterlab Rep.i. 19-22. Park, P. K., Broecker, W. S., Takahashi, T. & Reeburgh, W. S. (1975). Geosecs Bering Sea station, a brief hydrographic report. In Bering Sea Oceanography: An Update (D. W. Hood & Y. Takenouti, eds. ), pp. 207-244. Institute of Marine Science, Fairbanks, Alaska. Patton, C. J. & Crouch. S. R. ( 1977). Spectrophotometric and kinetic investigation of the Berthelot reaction for the determination of ammonia. Anal. Chem. 49, 464—469. Ryther, J. H. & Dunstan, W. M.(1971). Nitrogen, phosphorus and eutrophication in the coastal marine environment. Science 171, 1008-1013. Sambotto, R. M., Goering, J. J. & McRoy, C. P. (1984). Large yearly production of phytoplankton in the western Bering Strait. Science 225. 1 147-1 150. Scalan, R. S., Behrens, E. W., Caughey, M. E., Anderson, R. K. & Parker, P. L. ( 1 992). Characterization of sediment organic matter in the Bering and Chukchi Seas. (Subchapter 8. 5. 1, this volume.) Slawyk, G. & Maclsaac, J. J. (1972). Comparison of two automated ammonium methods in a region of coastal upwelling. Deep Sea Res. 19,521-524. Walsh, J. J., McRoy, C. P., Coachman, L. K., Goering, J. J., Nihoul. J. J., Whitledge, T. E., Blackburn, T. H., Parker. P. L.. Wirick, C. D., Shuert, P. G., Grebmeier, J. M., Springer, A. M., Tripp, R. D., Hansen, D. A., Djenidi, S., Deleersneider, S., Hendriksen, K., Lund, B. A., Andersen, P., Muller- Karger, F. E. & Dean, K. (1990). Carbon and nitrogen cycling within the Bering/Chukchi Seas: Source regions for organic matter affect AOU demands of the Arctic Ocean. Prog. Oceanogr. 22, 279-361. Whitledge, T. E., Bidigare, R. R., Zeeman, S. I., Sambotto, R. N., Roscigno, P. F., Jensen, P. R., Brooks, J. M., Trees, C. & Veidt, D. M. (1988). Biological measurements and related chemical features in Soviet and United States regions of the Bering Sea. Cont. Shelf Res. 12, 1299-1319. Whitledge, T. E.. Malloy, S. C, Patton, C. J. & Wirick. C. D. (1981 ). Automated nutrient analyses in seawater. Brookhaven Nat. Lab. Formal Rep. 51398, 227 pp. Whitledge, T. E.. Reeburgh, W. S. & Walsh, J. J. (1986). Seasonal inorganic nitrogen distributions and dynamic in the southeastern Bering Sea. Cont. Shelf Res. 5, 109-132. .49 Chapter 4: MICROORGANISMS AND MICROBIOLOGICAL PROCESSES Editors: ROGER B. HANSON & GENNADIY V. PANOV Subchapter 4.1: General Characteristics of Bacterial Populations 4.1.1 Total Number, Biomass, and Activity of Bacterioplankton ALLA V. TSYBAN, VASSILIY M. KUDRYATSEV, VLADIMIR O. MAMAEV, and NADEZHDA V. SUKHANOVA Institute of Global Climate ami Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow. USSR Introduction Until recently, marine microbiologists investigated only general characteristics of heterotrophic microorganisms. However, the development of new techniques (to measure biomass, growth rates, and metabolic activity) (Vieble, 1984), coupled with oceanographic measurements, has made it possible to quantitatively assess the importance of microorganisms in cycling of various organic and inorganic chemicals in the ocean. Such methods are now applied to detennine ecotoxicity and resident times of different anthropogenic contaminants. Investigation of microbiocenoses and quantitative assessment of microbiological processes in marine environment are the most important elements in the evaluation of anthropogenic inputs on marine ecosystem and their assimilation capacities. Information on the assimilation capacity can be obtained from long-term studies conducted across different geographical zones of the World Ocean (Izrael & Tsyban, 1983, 1989). Long-term microbiological research in the subarctic and arctic seas was started in the eariy 1980"s. Eariy results (Tsyban et al. 1987b; Izrael et al.. 1988) showed that the growth and function of microbiocenoses depended on the hydrological and hydrochemical conditions of the sea. The increase in human population and factors, and the transport of anthropogenic contaminants into the sea. has appreciably affected the growth and activity of marine microflora (Izrael & Tsyban, 1981, 1983a,b; Korsak, 1985). Materials and Methods Microbiological studies in the Bering and Chukchi Seas were conducted by the Soviet-American ecological expedition in summer 1988 (see Frontispiece). These studies paid particular attention to specific regions in these seas. In the Bering Sea, research efforts focused on the eastern and southern areas of the deep Bering Sea, the relatively shallow regions of the central area and the Gulf of Anadyr, and the shallow shelf area m the Chirikov basin. All these regions have unique hydrological, chemical, and biological conditions. To assess total population and biomass of bacteria, 381 samples were assayed in the BeringSea, of which 320 samples were assessed for dark CO, assimilation by bacteria. Microbiological studies were conducted for the first time in the Chukchi Sea. The study focused on the southern ice-free area of the sea to assess total number and biomass of bacteria; 1 1 5 samples were taken. For dark CO, assimilation by bacteria, 107 samples were taken at 21 stations. Total number of bacteria was determined directly on membrane filters "Synpor" with pore diameter of 0.32 |im (Razumov, 1932). A volume of 10 to 20 ml of water was filtered, cells stained with 5% erythrosine, and counted by light microscopy. Counts were done on 10-20 visual fields with a total magnification of xI.OOO. The number of bacteria was calculated by the formula: X: Sx lO^xa. S, X b xc where X = number of bacteria per one ml of water; s = filter area, mm-; 10*^ = coefficient for converting mm- to a = average number of bacteria counted in 1 visual field "c"; s, ^ area of eyepiece reticular network in fim-; b = volume of water filtered, ml; c ^ number of visual fields, where bacteria were counted over "S," area. The biovolume of bacterial mass was estimated from the average volume and total number of bacteria: where V n v, V = n X v, biovolume of bacterial mass, ^m'; number of bacteria per liter of water; average volume of a single bacterial cell, ;Um\ The linear dimensions of single bacterial cells were determined (Tsyban et al., 1988) with a calibrated eyepiece micrometer. From such measurements, the average volume of bacterial cells was calculated and equaled to 0.30 ;^m- . Bacterial mass was determined (Sorokin & Kadota, 1972; Romanenko & Kusznetsov, 1974) by the formula: Ph= nx vx 15x 10'' 2x 100 55 where 15 10-* 2 100 weight of bacterial biomass, jUg C/1; total number of bacterial per 1 of water; percentage of dry residue from raw biomass; weight of 1 ^m' of raw biomass of bacteria (/ig) with specific weight equal to unity; average biovolume of bacterial mass, jum'; carbon content from dry biomass; raw biomass, %. CO, dark assimilation by bacteria was assessed by radioisotopic method (Romanenko, 1964; Romanenko & Kuznetsov, 1974). To determine dark CO, assimilation by bacteria, the C'^ sodium carbonate (Na, "CO,; 20.4 x 10'~) was added to 100 ml of seawater. Water samples were incubated in the dark for 1-3 days at sea surface temperatures. After incubation, water samples were fixed with 40% formaldehyde solution and filtered (pore diameter 0.45 mm). Filters were exposed to 0. 1 N HCl vapors and radioactivity of bacteria on filter was measured by liquid scintillation. Rates were calculated by the formula c = *^-" ^ '■ Rxt where C, r R t CO, assimilation by bacteria, ^g C/1; carbonates concentration (mg/1), determined by directly titration (0.1 N HCl in the presence of methyl red indicator); radioactivity of bacteria on filters (dpm); radioactivity of isotope Na,"C03 used in experiment, dpm; incubation time. Results and Discussion Total Number. Bioma.^s. and Dark CO. Assimilaiion by Bacteria in the Bering Sea Results are shown in Table 1 . The growth, distribution, and activity of microflora varied both in time and locality in the Bering Sea. Bacterioplankton numbers, biomass, and activity in 1988 was generally higher than in the summers of 1981 and 1984(Tsybant'r«/.. 1987). In 1981 and 1984 the total number of bacteria fluctuated between 19-2,799 and 73-380 X 10' cells/ml. On average, the population and biomass of bacteria in 1988 amounted to 671 x 10' cells/inland 15.09 mg C/m', respectively. These values were almost twice as high as those found in 1981 and 1984. Comparing this data to other regions of the World Ocean, for instance, the total number of bacteria in the Barents Sea ranged between 10 and 500 x 10' cells/ml (Baitaz & Baitaz, 1986); in the Scotia Sea, populations of bacterioplankton reached 200-500 x 10' cells/ml (Azam et al.. 1981); in the Arctic Ocean, concentrations of bacterial population varied TABLE 1 Numbers, biomass and dark CO, assimilation by bacteria in the Bering Sea water, summer 1988. Sea area Total bacterial Bacterial biomass numbers (/jgC/l) (10-' cells/ml) Dark CO, assimilation by bacteria, /igC/l/d Bering Sea 283-1050 639 6.37 - 23.62 14.38 0.48- 1.73 0.98 Northern part of the Sea 276-1755 806 6.21 -39.49 18.13 0.49- 1.75 1,05 Gulf of Anadyr 381 -2391 727 8.57-53.79 16.38 0.09 - 2.02 0.38 Central part of the Sea .371 - 1601 722 8.35 - 36.02 16.26 0.09 - 2.69 0.53 East Polygon 147 - 3340 655 3.31-75.13 14.66 0.26-7.11 2.0 South Polygon 122- 1453 479 2.74-32.69 10.78 0.12-8.13 1.33 By and large in the Sea 122-3340 671 2.74-75.13 15.09 0.09-8.13 1.04 from 40 to 440 x 10' cells/ml (Dahlback et al.. 1982); in the region of Antarctic convergence, numbers varied from 200 to 350 X 10' cells/ml (Hanson et al.. 1983); and in oligotrophic areas of the Pacific, the density of bactenal population varied between 10' and 10"' cells/ml (Seki, 1986). Variations in the growth, number, and distribution of microflora in the Bering Sea with its complex mixture of water masses are specific to various areas in the basin. The maximum density of bacterial population was found on the shallow shelf of the Chirikov basin (Table 1). The total number and biomass of bacteria here were 2.7 times those in 1981. Relatively high bacterial population (1,755 x 10' cells/ml) and biomass (39.5 mg C/m') in this region were recorded at Station 106, located near St. Lawrence Island. In the northern part of the Chirikov basin, numbers and biomass of microflora were somewhat lower. Thus, at Station 96, the concentration of bacterioplankton was lowest, on average 583 x 10' cells/ml. Nevertheless, even though total bacterial numbers were comparatively low, the microflora activities were high. Daily dark CO, assimilation reached on average 1.42/igC/l. At other stations the bacterial activity was much lower, suggesting some bacterial cells were dormant. In the shallow northern part of the sea, a fairiy uniform distribution of bacterioplankton and reasonably steady level of acti\'ities occurred across the system. The surface microlayer showed relatively low concentrations of bacterioplankton, but bacterial activities were higher than in underiying waters. The bacterial dark CO, assimilation in the surface microlayer was, on average. I 2 1 pg C/1 daily, which corresponded to the level of mesotrophic waters. 56 Thus, the shallow northern part of the Bering Sea exhibited comparatively high total numbers and biomass and moderate activities of microflora and an even distribution of bacterial numbers across water types. From rates of bacterial activities and numbers, the microbiocenoses corresponded to mesotrophic modes. In contrast to the Chirikov basin, low microbiocenoses growth and absolutely different distribution of bacterioplankton were observed in the south Bering Sea (South Polygon, see Frontispiece). Total numbers and biomass of bacteria in this region comprised, on average, 479 x 10' cells/ml and 10.78 mg C/m'. This data is similar to those obtained in 198 1 (Tsyban et al., 1987). The moderate concentration of total bacteria and their biomass can be attributed to microorganisms being grazed by protozoa and microzooplankton. According to Mamae va ( 1 987 ), the evolutionary stage and metabolic activities of these grazers in the Bering Sea may be high. The variation in bacterioplankton distribution was clearly seen at South Polygon. The highest density of bacterial numbers (averaging 698 x 10' cells/ml) was found at Station 1 08; the lowest density (1 06 x 10' cells/ml ) occurred at Station 111. Three bacterial maxima were found in the water column. The first maximum occurred in the surface microlayer. The total number and biomass of bacteria in this layer averaged 1,027 X 10' cells/ml and 23.32 mg C/m', respectively, which was 1 .4 times that in the mixed layer. Microflora nourished in the surface microlayer because of various physical-chemical factors (e.g., particulate aggregates, nutrients, fatty acids and lipids) (Babenzien & Schwartz, 1970), from water-air interaction and from high surface tension. Japanese researchers (Saijo et al., 1974) have demonstrated that concentration of dissolved and suspended organic substances in the surface layer is 2-9 times that in the underlying layer. The second maximum of bacteria was found in the surface mixed layer (0.5—15 m), a zone of high phytoplankton biomass and photosynthesis. According to Fogg ( 1 97 1 ) and Kudryatsev ( 1973), the excretion of organic matter may constitute more than 20% of the total carbon produced by photosynthesis. The dissolved organic substances that are released by phytoplankton and other biota may be very important for bacterial growth. The results showed that maximum density of bacterial numbers (942 x 10' cells/ml) and high biomass (21.18 mg C/m') occurred at Station 1 08, and minimum numbers (427 X 10' cells/ml ) and low biomass (9.62 mg C/m') at Station 1 12. Below the euphotic zone, total number of bacteria and their biomass gradually declined. The third layer of high concentration of bacterioplankton occurred in the near bottom layers of water column. Thus, at Stations 110 and 111, near bottom bacterial population and biomass ranged from 510 to 761 x 10' cells/ml and 1 1.5 to 17. 1 mg C/m', respectively. Bacterioplankton activities also showed several maxima in the water column. In the euphotic zone of the south Bering Sea, bacteria appeared twice as active as those in the shallow northern part. Daily dark CO, assimilation by bacteria at South Polygon averaged 1.98 mg C/1. which is similar to bacterial activities in mesotrophic waters. Bacterioplankton activities in euphotic zone also correlated with the distribution of bacterial numbers. The highest dark CO, assimilation by bacteria occurred at Stations 108 and 1 10, where daily values averaged 2.43 and 2.73 /ig C/1, respectively. The lowest rate, 0.95 fig C/l/d, was at Station 109. Bacterioplankton activities declined with depth below the mixed layer in the south Bering Sea. However, between 150 and 2,000 m, relatively high activity of microflora was found, coupled with high dark CO, assimilation by bacteria that reached 2.0-3.0 /ig C/l/d. Thus, south Bering Sea possessed high bacterial activity, particularly in the euphotic zone, and low density of bacteria throughout water column. In this region, bacterial distribution showed considerable variation. Microbiocenoses also varied vertically across water column boundaries. Another studied region of the sea was the East Polygon (see Frontispiece) located on the eastern slope. At this site, depth of the water column ranged from 135 to 3,000 m and the water column possessed a mixture of water types, dissolved O, saturation, and temperature. All these factors undoubtedly intluenced the formation and structure of microbiocenoses and distribution of bacteria. Results showed relatively low activities, similar to results reported earlier at this site in 1981 (Tsyban etai. 1987). Total number and biomass of bacteria at East Polygon varied considerably (Table 1). Values averaged approximately 1 .4 times higher than those in the south Bering Sea. Maximum bacterial population (1,302 x 10' cells/ml) and high bacterial biomass (29.34 mg C/m') occurred at the shallow- water Station 5, and minimum bacterial (873 x 10' cells/ml) and low bacterial biomass ( 19.65 mg C/m') occurred at the deep-water Station 3, where bacterial activities were high. The highest rates of dark CO, assimilation by bacteria occurred here, averaging 2.94 /ig C/1, approximately 5 times higher than those measured at Stations 4 and 5. Bacterioplankton in the eastern region declined from the surface microlayer to the bottom. Maximum numbers (2,174 x 10' cells/ml) occurred at Station 4 where microbiocenoses showed a maximum stage of development in euphotic zone. The number and biomass of bacteria at East Polygon averaged 1,183 x 10' cells/ml and 26.62 mg C/m', respectively. Below the euphotic zone, bacteria and their biomass declined to their lowest values ( 103 x 10' cells/ml and 4.6 mg C/m') in near-bottom waters of 2, 700-3,000 m. Although microflora activities showed little variation with depth, dark assimilation of CO, by bacteria increased from surface layers to the bottom at Stations 2, 4, and 5. At Station 1 , maximum bacterial activity occurred in surface waters. Thus, the eastern Bering Sea possessed relatively high numbers, biomass, and activities of bacterioplankton in the surface microlayer and euphotic zone, but values tended to decline with depth. Microbiocenoses in the central basin and in the Gulf of Anadyr exhibit a position between northern and southern regions. The central basin is relatively shallow (45-145 m), with a sharp thermocline (between 25 and 45 m, temperatures ranging from 6.0 to 1 .0°C at Station 9) even though dissolved O, saturation remained constant with depth. 57 The bacterial density and biomass varied considerably between stations. Maximum average values of total numbers (1,103 X 10' cells/ml) and bacterial biomass (24.83 mg C/m') occurred at Station 6 and minimum values at Station 1 8, where values averaged 513 x 10' cells/ml and 11.55 mg C/m\ respectively. The distribution of bacterioplankton in the water column also varied with depth (Figs. 1,2). Numbers increased at the thermocline. In contrast to East and South Polygons, the surface microlayerhere lacked high concentrations of bacteria. Total numbers and biomass of bacteria averaged 691 X 10' cells/ml and 15.5 mg C/m', respectively. Highest density of bacterioplankton occurred in the euphotic zone, and cell number and bacterial biomass averaged 790 x 10' cells/ml and 17.8 mg C/m', respectively. Bacterial numbers declined with depth, but near the bottom, numbers reached a density of 708 X 10' cells/ml. Vertical and honzontal distribution 86 89 100 104 0 , ■ 05 10 E 15 t 25 a 0 os' 10 15 Vertical and horizontal distribution Scale 10 /ml 05 10 15 Stall L>n Localion^ "^ ^ 86 ^r vV ! ^' r "96 • ^89^ "^ ^ si 100 • 104 102 ' Fig. 1. Distribution of bacterial population in the northern Bering Sea, summer 1988. Compared to other areas, bacteria in the central basin showed the lowest activity (Table 1 ), and rates of dark CO, assimilation compared with those in oligotrophic waters. Maximum activity of bacterioplankton occurred at Station 7, where rates averaged 1 . 1 1 /ig C/l/d. At Stations 6, 1 8, and 19, all rates varied between 0.20 and 0.30 jjg C/l/d. In the surface microlayer and euphotic zone, microflora showed similar rates of dark CO, assimilation, averaging about 0.50 ng C/l/d. Near the bottom, rates averaged 0.37 /Jg C/l/d. Thus, in the central basin with shallow depths and strong thermocline, the bacteria numbers and biomass are modest but bacterial activity is low. In the Gulf of Anadyr, river effluence influenced microbio- cenoses. The Anadyr River discharges nearly 41 km' yearly into the Gulf of Anadyr (Dobrovolski & Zalogin, 1982). Fig. 2. Distribution of bactenal population in the southern Bering Sea, summer 1988. During the summer, surface salinities in the gulf waters declined, and terrestrial microorganisms and suspended organic matter of terrigenic origin enter the sea. Consequently, bacteria that absorb to suspended matter may seriously influence the structure of coastal bacterial populations. Total numbers and biomass of bacterioplankton in the Gulf of Anadyr are high (Table 1 ) and as high as those in the northern basin. Maximum numbers and biomass occurred at Stations 24 and 26 located in the gulf coastal waters, with minimum values at Station 22 nearest the open sea. Vertical profiles of bacterioplankton showed some increase in both numbers and biomass with depth (Fig. 3). The bulk of bacterioplankton concentrated in the euphotic zone where total numbers and biomass averaged 910 x 10' cells/ml and 20.5 mg C/m', respectively. Near-bottom waters contained the lowest density of bacteria in the water column. Bacterioplankton in the Gulf of Anadyr showed the lowest activity relative to other studied areas. This suggests that most of the microflora were dormant. The highest activity of microbiocenoses occurred at Station 26, the lowest activity at Station 1 1 . Dark CO, assimilation by bacteria at those stations averaged 1.11 andO. 17 ^ug C/l/d, respectively, and distributed evenly throughout the water column. Dark CO, assimilation in the surface microlayer, euphotic zone, and near the bottom ranged between 0.48 and 0.50 ^ug C/l/d. Thus, high density of bacterioplankton and low activities of microbiocenoses characterized the shallow Gulf of Anadyr with its sharp thermocline and low surface salinity. Generally speaking, bacteria remained constant with depth, although at Stations 1 5 and 22, highest numbers and activities of bacterioplankton occurred at the thermocline. In conclusion, by studying bacteria in the Bering Sea in summer 1988, it was possible to assess the status and variance of total number, biomass, and activities of bacterioplankton in relation to different hydrological and chemical conditions and 58 Venical and horizontal disinbuiion of cells. Siaiion Locaiions "."X -h 4 ) y 24 1 1 I C:: Fig. 3. Distribution of bacterial population in the Gulf of Anadyr of the Bering Sea, summer 1988. to compare them with the data obtained in previous years. Relating bacterial numbers, biomass, and activities with other oceanographic parameters, it was possible to analyze the microbiological conditions with increasing anthropogenic load in the Bering Sea ecosystem. Total Number, Biomass. and Activity of Bacterioplanktim in the Chukchi Sea Until recently, there has been no microbiological studies in the Chukchi Sea ecosystem. The first investigations, conducted in suinmer 1988, focused on bacterioplankton, their distribution, and biological status of the microbiocenoses. Microbiological studies included variance across the region, vertical distribution of bacterial nuinber, biomass, and activity. The Chukchi Sea is one of many adjacent seas of the Arctic Ocean. It freely communicates with cold waters to the north and limitedly with the Pacific. Nevertheless, every year 30,000 km' of water flow into the Chukchi Sea from the Pacific through the Bering Strait (Dobrovolski & Zalogin, 1982). Sea water teinperatures depend mostly upon solar warming and autumn-winter cooling. The space-time scales for salinity depend on the inflow of Pacific waters and river waters from coastal areas. The horizontal and vertical variance of dissolved oxygen and biogenic elements affect the formation and growth of microbiocenoses. The analysis of results (Table 2) shows that total number of bacteria and their biomass in the Chukchi Sea varied across locality and depths. In coastal waters of Chukchi and Alaska, maximum numbers and biomass of bacteria occurred. These regions are strongly influenced by both river effluence and Pacific Ocean waters. Deep-ocean waters from the Pacific, which are warm and enriched with biogenic nutrients, penetrate through the Bering Strait and mix with Chukchi Sea, resulting in varied growth and distribution of microbiocenoses across the Chukchi Sea. The activity of Chukchi littoral bacteria was high and equal to that of mesotrophic waters. Bacterioplankton showed the lowest activity in Alaskan waters. The distribution of bacterioplankton along sections across different water types (Fig. 4) can be attributed to water depths (0-45 m), temperature (0. 1-5.2°C), salinity (30.6% to 33.6%), and dissolved oxygen (from 51% to 98%). TABLE 2 Assessments of population, biomass and dark CO, assimilation by bacteria in Chukchi Sea Waters, summer 1988. Sea regions Total population Bacterial explored of bacteria bioinass 10' cells/ml (/igC/1) Dark CO, assimilation by bacteria, pg C/l/d Sea northern region 443 - 1987 913 9.97-44.71 20.55 0.13-2.79 1.00 Alaska coastal region 443 - 1908 923 9.97 - 42.93 20.97 0.12- 1.23 0.66 Sea central part 496-1718 875 11.16-38.65 19.69 0.47-4.01 1.61 Chukchi coastal area 305- 1385 967 6.86-31.16 21.76 0.47 - 3.67 1.57 On the whole over the Sea 305 - 1987 919 6.86-44.71 20.69 0.12-4.01 1.21 Maximum density of bacteria (averaging 997 X 10' cells/ml) occurred near the bottom in the Chukchi Coastal waters. In the euphotic zone and surface layer bacteria and their biomass were almost 1 .5 times lower than those near the bottom. In the Alaska littoral zone, bacterioplankton were most abundant between 0 and 25 m. In this layer, numbers and biomass averaged 92 1 x 10' cells/ml and 17.92 mgC/m'. In the surface microlayer and near the bottom bacterioplankton were somewhat lower than the euphotic zone. Due to mixing in the northern area of the sea, bacteria remained constant with depth as did hydrological and chemical factors. In the Chukchi Sea, the growth of bacteria equalled that of mesotrophic waters. The highest number of bacterioplankton occurred at Station 46. where bacteria and their biomass averaged 1.154 x 10' cells/ml and 25.96 mg C/m'. respectively. High bacterial activity also occurred at Station 45. The highest daily dark CO, assimilation by bacteria was averaged (2.08 /ig C/1) at Station 50. where bacterial numbers and biomass average 765 x 10' cells/ml and 17.01 mg C/m'. respectively. Vertically, total number, biomass, and activity of bacterioplankton increased from the surface microlayer to the bottom (Fig. 3). The waters in the central basin of the Chukchi Sea showed variable temperatures and dissolved oxygen. Waters mixing over this area distributed bacteria within specific localities. Maximum numbers occurred at Stations 55 and 74, and numbers and biomass of bacteria averaged 1,028 and 59 0 5; 15. <5 55J Vertical and honznntal disuihulion ol celK 69 61 57 10 telK/m 0 5 10 15 SIdUur i.ic liur 45 47 •' ,30 ( y • • 57 ^x r ba •- ^61 -• > 69 64 • - 65\ --• \ V^ •74 ^■^ Fig. 4. Distribution ofbacterial population in the Chukchi Sea, summer 1 ? l,108x lO'cells/ml and 23. 14and24.94mgC/m\ respectively. Minimum numbers and their biomass occurred at Station 57. where values averaged 446 x 10' cells/ml and 10.49 mg C/m\ In the central basin, highest bacterial activity compared with the other study sites. Maximum dark CO, assimilation by bacteria occurred at Station 64, where the rates equaled that of eutrophic waters. Minimum values occurred at Station 74. Vertically, numbers and biomass of bacterioplankton peaked between 0.5 and 25 m thick relative to values in the microlayer and near-bottom waters. In conclusion, microbiological studies were made for the first time in the Chukchi Sea. Water masses of the Chukchi Sea showed a high level of microbiocenoses growth comparable to mesotrophic waters. Additionally , bacterial numbers, biomass, and activity in the waters of the Chukchi Sea exceeded those found in the Bering Sea. 4.1.2 Thymidine Incorporation, Frequency of Dividing Cells, and Growth Rates of Bacterioplankton ROGER B. HANSON and CHARLES Y. ROBERTSON Skidaway Institute of Oceanography. Savannah. Georgia. USA Introduction The Third Joint US-USSR Bering & Chukchi Seas Expedition offered a comparative regional and depth analysis of bacterioplankton in the ice-free Chirikov basin and the south Bering Sea during late July and early August 1 988. This study focused primarily on the Chirikov basin, the region between the St. Lawrence Island and the Bering Strait. Two deep-water stations in the south Bering Sea ecosystem were also examined. The principal objectives were to characterize the spatial distribution and potential growth rate of bacterioplankton, to estimate bacterioplankton productivity, and to assess their importance relative to primary production in the western and eastern Chirikov basin. The results from this study provided some essential, first time estimates of bacterioplankton production, growth rate, and biomass in the shallow ecosystem of the northern Bering Sea and in deep waters of the south Bering Sea. 60 Materials and Methods Study Area and Slalion Locations The second leg of ihe 1988 US-USSR cruise aboard the research vessel Akademik Korolev focused pri manly on the shallow Chirikov basin (<50 meters), the region between St. Lawrence Island and the Bering Strait (see Frontispiece). In the Chirikov basin, three major water types occur and are bathymetrically steered northward across this northern Bering Shelf. Anadyr water (AW) is located in Soviet waters along the western boundary of the system. The Bering Shelf water ( BSHW) is restricted to the central basin; and Alaskan Coastal water ( ACW) is located near the Alaskan coast and forms the eastern boundary of the northern shelf ecosystem. These waters are identified by temperature/salinity profiles and bottom water properties. In the summer, AW is characterized with salinities >32.5"/(ki and temperatures 4°C (Walsh f/«/., 1989). Two additional areas were also made in deep water of the south Bering Sea basin near the Aleutians (see Frontispiece). Bacterioplankton dynamics were measured at Station 1 10 in the South Polygon (53°9'N. 175°9'W) and at Station 113, the old GEOSECS station in the eastern Bering Sea basin (53°2'N, 177°3'W). Physical Measurements Salinity, temperature, and depth data were collected using a Sea-Bird SBE9 CTD/General Oceanic Rosette System. This information was used to select water depths for bacterioplankton samples. TCA and were dissolved in Aquasol. Radioactivity, corrected for counting efficiency using an internal 'H standard, was detennined by liquid scintillation. Bacteria in 10-ml water samples were preserved with 0.2 |im filtered formaldehyde (2% final concentration) and stored at 5°C. One to 3 weeks following the cruise, bacteria were stained with Acridine Orange and filter on 0.2 |im Nuclepore filters for counting total bacteria in 10 microscopic fields filter ' (Hobbie etal.. 1977), along with dividing cells in 20 microscopic fields filter ' (Hagstrom el al., 1979). The frequency of dividing cells were calculated relative to the total number of single plus dividing cells. Bacterial numbers and dividing cells were determined by epifluorescence microscopy . Estimates of cell production and growth rates in natural populations of bacteria were calculated using two different techniques: thymidine incorporation into DNA material using the theoretical conversion factor of 2 x 10'* cells mole ' thymidine incorporated (Fuhrman & Azam, 1982) and the frequency of dividing cells using the empirical relationship between FDC and specific growth rate (u) of In u = 0.81 (FDC) -3,73 for southern ocean bacterioplankton (Hanson etal., 1983). Growth rates were calculated from estimates of cell production divided by standing stocks of bacteria. To convert cell production and standing stocks to carbon, an estimate of cell carbon was assumed to be 10 fentogram C cell ' based on estimates from Antarctica and British Columbia (Fuhrman & Azam, 1980; Fuhrman, 1981). Statistics Analysis Data transformation and statistics analysis (i.e., correlations, slope analysis, t-test, ANOVA) were computed with SAS, Inc., software. Bacterioplankton Measurements On the shallow Bering Sea Shelf, water samples for bacterioplankton measurements were collected from ? depths at 12 stations using 1.7-1 Niskins bottles on the rosette. Sample depths were chosen to represent surface mixed waters, hydrographic conditions within the region (i.e.. themiohalocline or midwater column), and near-bottom waters. In the deep Bering Sea at Stations 110 and 113, water samples were collected from 1 2 depths: 6 depths in the upper 250 m of the water column and 6 depths over the remaining water column down to the bottom. Bacterioplankton measurements included l"H-methyl|thymidine incorporation, bacterial numbers and frequency of dividing cells, and empirical growth experiments. For thymidine incorporation (Fuhrman & Azam. 1982). unaltered ?0-ml water samples were transferred to an 8-oz sterile Whiri Pak bag. | 'H-methyl|thymidine (84.8 Ci mmol ' ) was added to obtain a final concentration of 20 nmoles 1 '. Water samples were incubated in the dark at in situ surface temperatures. After 3 h. samples were chilled in an ice bath and ice-cold trichloroacetic acid (TCA) was added to a final concentration of S'/f TCA. After30minonice, 25-ml replicate samples were filtered on 25-min Millipore cellulose acetate filters of 0.45 |i pore size. The filters were rinsed with cold 57c Results and Discussion Bacterioplankton. Thymidine Incorporatum. and Frequency of Dividing Cells Anadyr water ( AW): Rates of thymidine incorporation by bacterioplankton along the western boundary of the Chirikov basin remained constant with depth, except at Station 86 where rates refiected the themiohalocline in the Bering Strait (Frontispiece, Figs. Ia,b). Ratesaveraged 1.37 pmolesl' h ' in AW (Table I ). Salinity profile at Station 86 characterized low- salinity ACW in the upper 15 m and high-salinity AW below 30 m. Rates of thymidine incorporation correlated strongly with temperature but not with the index of the population growth rate (i.e., specific activity of thymidine incorporation) (Fig. 2, Table 2). Bacterial populations were generally more abundant in surface waters in AW and averaged 3.7 x 10" cells 1 '. Highest numbers occurred in the surface waters of the Bering Strait (Station 86, Fig. la). Bacteria in these waters correlated with the narrow range in water temperatures (Fig. 3. Table 2). This relationship to the index of population growth rate was similar to that found for ACW (Fig. 2, Table 2). The frequency of dividing cells, an index of cellular growth rate, ranged from 4 to 8% dividing cells in surface 61 waters at all stations. Below the minimum frequency of dividing cells (<4%), dividing cells again increased with depth to5.1%nearthebottom(Figs. la,b). The frequency of dividing cells averaged 4.4% dividing cells over the water column. The specific activity of thymidine uptake, population growth rate, averaged 4.04 x 10 -' moles cell ' h ' (Table 2) and showed no relation to the frequency of dividing cells, cellular growth rate, except at Station 86. Both indices of growth rates showed no relation to temperature (data not shown). Alaskan Coastal water: With the exception of Station 9 1 where the water column was isothermal ( 10°C), ACW showed a strong thermocline near 10 m (Figs. 4a,b; 5a,b). Rates of thymidine incorporation along the eastern boundary of the Chirikov basin averaged 1 .55 pmoles 1 ' h ' but not significantly different (P = 0.05) from the rates measured along the western boundary (Table 1 ). At Station 84 in the Bering Strait and Station 91, thymidine incorporation varied little with depth, whereas at Station 92, the highest rates occurred within the thermocline. At Station 102 northeast of St. Lawrence Island, thymidine incorporation increased in the high salinity bottom waters (Fig. 4b). Rates of thymidine incorporation were related inversely with temperature and positively with the index of the population growth rate (Fig. 2, Table 2). Rates measured in the bottom waters of the eastern Bering Straits clustered with rates measured in the waters of the western boundary of the Chirikov basin (AW, see Fig. 2), suggesting similar bottom waters flowing through the eastern and western sides of the Bering Strait. Bacterial populations averaged 3.6 X 10* cells 1' (Table 1) and were also similar to population densities in AW. Highest densities occurred above the thermocline at Stations 92 and 102 and were approximately constant with depth at Stations 84 and 91 (Figs. 4a,b; 5a,b). Bacterial populations in ACW showed no relation to temperature. The frequency of dividing cells in ACW averaged 0.037 (3.7% dividing cells) (Table 1). The highest frequency of dividing cells (5.0%) occurred near the themiocline and declined towards the bottom, except at Station 91 where dividing cells remained constant over the water column. The specific activity of the population averaged 4.85 x 10^' moles cell ' h ' (Table 1 ) and was similar to the specific activity measured in AW. The specific activity showed no relationship to dividing cells except at Station 84 in the Bering Strait. Similar observation was seen at Station 86 in the western Bering Strait. Bering Shelf water: Waters at Stations 89, 100, 104, and 1 06 characterized BSH W ( Figs. 2,3 ). Waters at Stations 89 and 106 nearest to the western boundary of the system typify AW with bottom temperatures <2°C, whereas low-salinity ACW dominates surface waters near the eastern boundary at Stations 100 and 104. Rates of thymidine incorporation averaged 1 .70 pmoles 1' h ' (Table 1 ). Highest rates in BSHW occurred at Station 104, northeastof St. Lawrence Island (Fig. 3). Rates were highly variable with temperature (P > 0.05) but correlated significantly with the specific activity (Fig. 2, Table 2). Bacterioplankton populations averaged 5.2 x 10" cells 1 ' (Table 1 ) and were significantly higher than the Anadyr and ACWs ( ANOVA, P < 0.05). The highest densities occurred TABLE 1 Vertical distribution of averaged bacterioplankton parameters from the three water types measured in the Chirikov basin. Units: N = number of samples averaged at each depth, depth = meters. Thymidine Incorporation = pmoles 1 ' h ', Bacteria = 10" cells 1 ', Specific Activity of thymidine incorporation = 10-' moles cell ' h '. Anadyr Waters Thymidine Freq. Specific N Depth Incorp. Bacteria Dividing Activity 4 05 1.66 4.2 0.035 4.02 4 10 1.46 4.7 0.056 3.01 3 15 1.31 3.3 0.038 3.95 3 20 1.07 1.9 0.032 6.04 2 25 1.26 44 0.053 2,92 4 40 1.31 3.6 0.051 4.23 average 1.37 + -0.11 3.7 + -0.3 0.044 -1- -0.004 4.04 -1- -0.36 Alaskan Coastal Waters Thymidine Freq. Specific N Depth Incorp. Bacteria Dividing Activity 05 10 15 20 25 30-35 1.39 1.53 1.55 1.81 1.58 1.54 3.1 4.4 3.5 3.9 3.9 2.3 0.036 0.050 0.038 0.033 0.026 0.035 4.66 3.48 4.69 4.96 4.82 6.55 average 1.55-0.09 3.6-0.2 0.037-0.003 4.85-0.54 Bering Shelf Waters Thymidine N Depth Incorp, Bacteria Freq. Dividing Specific Activity 3 05 1.89 5,1 0.051 3.94 3 10 1.87 4,7 0.044 3.71 4 15 1.97 5,7 0,044 3,52 4 20 1.58 6,1 0,034 2,96 3 25 1.57 5,0 0,029 3,33 3 30-40 1.30 3,8 0.027 3,41 average 1.70-0,19 5,2-0,5 0.038-0,003 3,45-0,28 overall mean 1,54-0,08 4,1-0.2 0,040-0.002 4,11-0,24 above or within the thermocline. Bacteria numbers were also highly variable with temperature and specific activity (Fig. 3, Table 2). The frequency of dividing cells averaged 0.038 (3.8% dividing cells) (Table 1 ), In general, frequency of dividing cells decreased from 5.1% in the surface to 2.9% below the thermocline. The specific activity averaged 3.45 X 10^' moles cell ' h ' (Table 1 ), which was significantly 62 THYMIDINE INCORPORPATION 0 12 3 4 I — » — I — I — ' — I — r- THYMIDINE INCORPORPATION 0 12 3 4 I — T~i — r — I — I — I — I — I — I — r — ' — ' — ' — ' — I — ' — ' — ' — ' — I J BACTERIA ) 2 4 6 8 10 5 A oAnadyr \ ^^ Waters 10 IS CTA ^ Stc. 86 ^20 \ \ L 30 / 1 / 1 35 / 1 40 K 6 45 . 0 BACTERIA 2 3 4 5 6 7 8 9 Anadyr 5 Q 4 Waters 10 6^^ Sto. 95 15 Js-'O X 1— Q.20 LiJ Q 23 - <^ / 30 y^^^ 35 ;\. 40 O \k FREQUENCY OF DIVIDING 12 3 4 5 6 7 8 I t I I I [ I I I I I I I I I 1 I I I 1 I 1 I I I I I I I I I I I I I I 0 § 18 15 - 15 - ^ 20 - a. 20 UJ,5|. Q 25 - 30 48 1- SPECIFIC ACTIVITY 4 6 8 10 — 1 TEMPERATURE 123456789 10 I ' ' ■ ' 1 ' ' ' ■ I ' ■ ■ ' I ' ' ' ' I ' ' I I I I I I I I I I ■ ■ I SALINITY 31 32 33 34 35 —I — T — I — T — 1 — f—T — I— I— I — I — I — I — I — r— I — I — I — I — I — I 0 5 10 15 X I— Q.20 UJ Q 25 35 40 FREQUENCY OF DIVIDING 12 3 4 5 6 7 8 ftTIT]llll|IIT1ITTI(I>1ll|ITI)Illlt) SPECIFIC ACTIVITY 2 3 4 5 6 7 8 I I I I I I I I '' I I I ' I ' I I ' I ' I I I I I I I I ' I I TEMPERATURE 3456789 10 ■ I ■ ' I ' I ' 1 1 1 1 I I I 1 1 I I ■ I I I I I ' I I ' ' ' 1 1 1 1 1 1 SALINITY 31 32 33 5 - iiTT|tiii|ii — I r' \' 1 34 -" — 1 9 15 -e X 1 1- a. 20 - 6 UJ Q 25 . 30 1 35 J 40 . 6 to. Figure la. The vertical distribution of thymidine incorporation (pmoles 1 specific acliviiy of thymidine incorporation (10'-' moles cell ' h '), bacteria (10' cells 1 'l, frequency of dividing cells ("5 of total bacteria), h '), temperature (°C). and salinity ("A.O at Stations 86 and 95 (AW). 63 THYMIDINE INCORPORPATION 0 12 3 + THYMIDINE INCORPORPATION —I — r--r — f ' ■ r -T 1 1 1 1 1 BACTERIA 2 3 4 5 6 7 8 9 s 10 : ,7 Anadyr Waters Sta. 96 15 X h- Q.20 LJ Q 25 ■ i 30 I 1 35 1 40 L i 6 2 — 1 1 r- 3 4 —I r— T r— t — 1 BACTERIA 23456789 -T — r — 1 — I — I — I — > — 1 Anadyr Waters Sta. 98 5 10 15 I I— a. 20 UJ Q 25 40 FREQUENCY OF DIVIDING 2 3 4 5 6 7 8 I I ' I ' ' r ' ' ■ ' I ' ■ ' I I ' ' ' ' I ' ' I ' I ■ ' ■ ' I SPECIFIC ACTMTT m-i-P-r-i-r-T-n .X) 1 2 TEMPERATURE 3 4 5 6 7 8 9 10 0^° SALINITY 31 32 33 34 5 - Q 1 t I 10 - 6 I L 15 - 0 i \ X 1— Q. 20 UJ Q 25 - 6 I i 30 - ' 35 - 1 40 -A I k FREQUENCY OF DIVIDING 2 3 4 5 6 7 8 r T r r 1 r n r ^ T y y ii i-^ ti i t t"^ i"t~t |~t~t i t t SPECIFIC ACTIVITY 0 5 2 3 4 5 6 7 8 - 10 - i<^0 15 I 1— Q. 20 Ld Q 25 - \ 1 1 ^ s ii!i 30 \ \ \ \ 35 " \ \ 40 L X iD TEMPERATURE 1 23456789 10 1 ■ ■ ■ I I ' ' ' ■ I ' ' ' ' I ■ ' ' ' I ' ■ ' ■ I ' ' ' ' I ' ■ ■ ■ I ' ' ' ' I ' I I ' t SALINITY 15 I h- Q.20 LjJ Q 25 30 35 40 31 32 33 34 — 1 — r — ) — I — r— I — I — I — I — I — I — I — I — I — I — I Q I O 6 Figure lb. The vertical distribution of thymidine incorporation, bactena, frequency of dividing cells, specific activity, temperature and salinity at Stations % and 9X(AWs). 64 THYMIDINE INCORPORPATION 0 12 3 4 r- T- ~r~ BACTERIA 0 1 2 3 4 5 6 7 B 9 10 11 12 13 14 1 ' 1 ' r ■ I ' 1 ' 1 ' 1 ' I ' I ' I ' I ' I ' I ' I ' -iSr- -T«e — A- — Bering Sea sta. no THYMIDINE INCORPORPATION 0 12 3 4 I — I 1 — 1 1 1 1 ( 1 — f — I r — I 1 1 1 1 1 1 1 1 BACTERIA 0 1 2 3 4 5 6 7 S 9 10 1112 13 14 1 ■ r ' r ' 1 ' I ■ r ' I ' 1 ■ [ ' [ ' I 1 I I I ' I ' I ^&— Qffl>> & Bering Sea Sta. 113 FREQUENCY OF DIVIDING 12 3 4 5 6 7 8 1 ' I ' ' I ' ' ' I t ' ' ' ' I I ' ' ' I ' ■ ' ■ [ ' ■ ' ' I ' ' ' ' I SPECIFIC ACTIVITY 0 12 3 4 -1 — 1 — I — I- r~ OcO--A=-=^ -1 — r- 500 1000 1500 CL2000 u a 2500 3000 3500 4000 ^- -© (X FREQUENCY OF DIVIDING 1 2 3 4 5 6 7 8 1 ■ ■ ' ' I I I I I 1 I I I 1 r ' ' I ' I I I ' I I ' I I I I I I I ' I SPECIFIC ACTIVITY 1 2 3 -] — I — I — 1 — I — r— 1 TEMPERATURE 4 5 6 7 8 ' ' I ' ■ ■ ' I ' ' ■ ■ I ■ I I ■ I ■ ' ' ' I ' SALINITY 1 2 I ■ ' ' I I ' 32 1 1- 35 TEMPERATURE 3 4 5 6 7 8 9 SALINitV 33 34 0 500 : ^0 / 1000 : f^ : ® DEPTH sis : / : / - / '- 0) c ' I ' 3000 ■ 1 - CD • 1 3500 ■ 1 ' 1 ; 6 4000 -OD 4000 Figure 2. The venical distribution of thymidine incorporation ( pmoies 1 ' h ' ), bacteria (1 0' cells I ' ), frequency of dividing cells (% of total bacteria), specificactivity of thymidine incorporation (10 -' moles cell ' h'). temperature {°C), and salinity ("A.,) al Stations 110 and 1 13 in the south Bering Sea. 65 §4. O o u _c c '-0 -I I- a) "T 1 <- 5 —1 r- 10 Specific Activity — 1 13 a i_ o B-^ o u c c s: 1 - c) I I ' I 0 1 2 I ' I 3 4 I I I I I 5 6 7 Temperature I I I I I I I 9 10 11 12 -" — I — r- 10 —I 15 Specific Activity 4- o - o u _c c 1'^ d) A ^ ■'A ^ a/ /o / A A / / I I I I I I I I I ' I I I I I ■ I 4 5 6 7 8 9 10 11 12 Temperature Figure 3. Linear regression of thymidine incorporation plotted against specific activity (a.b)and temperature (c.d). Figs, 3a and 3c show data from ACW's (circles) and AWs (squares), and Figs. 3b and 3d show data from BSHW's (triangle) and BSW's (diamond). Statistics for linear regressions are given in Table 2. 66 THYMIDINE INCORPORPATION 12 3 4 THYMIDINE INCORPORPATION 0 12 3 4 BACTERIA 2 3 4 5 6 1 1 — ' — r — I — T — ' — r— BACTERIA 4 5 6 Alaskan Coastal Water Sta. 84 5 10 15 X I— 0.20 UJ Q 25 30 35 40 Alaskan Coastal Water Sta. 91 FREQUENCY OF DIVIDING 5 6 ' I ' ' ■ ' I ■ SPECIFIC ACTIVITY TEMPERATURE 0 5 - 10 - 15 CL 20 - bJ Q 25 - 1 2 3 4 5 6 7 8 9 10 ? D r— 1 — 1 — r 31 SALINITY 32 33 1 1 1 1 1 1 1 1 1 1 T— 34 30 40 FREQUENCY OF DIVIDING 2 3 4 5 6 7 8 ' I ' ■ ' ' I ■ ' ' ' 1 ' ' ' ' I ' ' ' ' I ' ' ' ' I ' ' ' ' I SPECIFIC ACTIVITY 2 3 4 5 6 7 8 TEMPERATURE 23456789 30 31 SALINITY 32 10 IS Q.20 UJ Q 25|-A 30 3S 40 -1 — I 1 1 1 T" 10 1 ' ' ' M ' ' ' ' 1 ■ ' ' ' 1 ' ■ ' ' 1 ' ' ■ ■ I ' ■ ' ■ I ■ ■ ' ' I 34 9 I 6 I 1 I 6 Figure 4a. The vertical distribution of thymidine incorporation (pmoles 1 ' h '). bacteria (10" cells 1'), frequency ofdividing cells (% of total bacteria), specific activity of thymidine incorporalion (K)-' moles cell ' h '), temperature (°C), and salinity ("/m) at Stations 84 and 91 (ACW's). 67 THYMIDINE INCORPORPATION 0 12 3 4 I — I — I — I — I — 1 — I — I — 1 — I — I — I — I — 1 — I — I — t — I — 1 — I — 1 BACTERIA 123456789 Q. 20 UJ Q 25 30 35 40 — 1 — 1 — <- A -I — 1 — r — <— I'll "^-^ ©^ 1 ■ ' I 1 1 - d ^ Alas kan Coastal Water L Sta. 92 THYMIDINE INCORPORPATION 0 12 3 4 r — 1 — 1 1 1 — I — r — 1 1 1 — 1 — 1 — 1 1 — 1 — I — 1 — 1 — 1 — 1 — I BACTERIA 1 23456789 5 10 15 X I— Q. 20 UJ Q 25 30 35 40 -~t--l - 1- T r r 1 , 1 I 1 •^ X > ® i b Alaskan . Sta. 102 Coastal Water FREQUENCY OP DIVIDING 2 3 4 5 6 7 8 1 SPECIFIC ACTIVITY 2 3 4 5 6 7 S 10 15 - Q_20 UJ Q 25 30 35 40 1 ' ' ' ' I ' - o' TEMPERATURE 1 23456789 10 1 I I I ' I ' I I ' I ' ' ' ' I ' ' ' ■ I ' ' ' ' I ' ' ' ' r ' ' ' ■ 1 ■ ■ ' ' I ' ' ' ' I SALINITY 30 31 32 33 34 5 - 10 "^^"^^ . - ' ' ®^ IS ©^ — ^ T / 1— / 0.20 Cp A UJ n 25 6 h 30 ■ 35 - FREQUENCY OF DIVIDING 12 3 4 5 6 7 8 5 - 10 15 0,20 UJ Q 25 30 35 I ' ' ' ' I ' ' ' ■ I ' I ' ' ' '"i SPECIFIC ACTIVITY 12 3 4 5 6 7 8 .30 40 5 10 15 - Ql20 UJ Q 25 30 - 35 - 40 - I ' ' ' ' 1 ' TEMPERATURE 3 4 5 6 7 8 9 10 I ' I I ' I I ' ' I I ' ' ' ■ r ' ' ■ ■ I ' ' ■ ■ I ' ' ' ' I ■ ' ' ' I ■ ■ ■ ' I ' SALINITY 31 32 33 34 — I — I — I — I — I — \ — 1 — I — I — 1 — 1 — r- ©■ o I 6 Figure 4b. The vertical dislribulioii ol ihyniidine incorporation (pinoles 1 ' h '). bacteria ( 11/ col Is I '), trcqiiency ol dividing cells (% of total bacteria), specific activity ol thymidine incorporation (I0-' moles cell ' h '). temperature ( C), and salinity ("/.) at Stations ^1 and 102 (ACW's). 68 THYMIDINE INCORPORPATION 0 12 3 4 I — I — I — I — I — r — ' — « — I — • — 1 — ' — r "T — T — I — 1 r- BACTERIA 123456789 15 1— Q. 20 UJ Q 25 -1 — 1 — I 1 — I 1 \ — 1 — I — I — I — 1 — I — 1 1 Berinql Shelf Waters Sta. 10 15 I f- 0.20 LiJ Q 25 30 35 40 THYMIDINE INCORPORPATION 12 3 4 — I — r— 1 1 — 1 1 — I— I 1 1 — I 1 — I 1 — I 1 1 1 — 1 BACTERIA 234567B9 1 — 1 — I — t — I — I — • — T — ' — r — I — I — ' — I — ' — 1 Bering Shelf Waters Sta. 106 FREQUENCY OF DIVIDING 12 3 4 5 6 7 8 I I I I I I I I I 1 SPECIFIC ACTIVITY .12345678 0 5 - till I » ' ' 1 T 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r r 1 1 10 r -^^ 15 - >^ :o I 1- 0.20 bJ Q 25 - ^ - / 0 30 - / / \ / \ 35 - / / / / \ 40 L O A TEMPERATURE 1 23456789 10 ri 1^1 I r I I ^'7 T T I r [T-i TT T r t-r r I T^ ^' I ' ' ' ' I ' ' ' ' I t-f-t-i SALINITY 30 31 32 33 34 Q. 20 LiJ Q 25 30 - — I 1 1 1 1 1 1 1 1 < \ 9^ I I FREQUENCY OF DIVIDING 12 3 4 5 6 7 8 I I ' ■ I I ' I ' ■ [ ■ ' ' M ' ' ' ' r ' ' I ■ I ■ ' ■ ' I ' ■ ■ ' I SPECIFIC ACTIVITY 12345678 5 - 15 Q. 20 bJ Q 25 30 35 I ' ' ' ■ I ■ ' ' ' I t ■ I I 1 I I I I 1 /^t) TEMPERATURE 123456789 10 I I r I I I I I I I [ I I I I I I ri 1 I * T I rt T ITT'T T riT rf-T-TTT-mn SALINITY 10 15 0.2TTTTItT'TT-rT I fTTTT-f 1'1 t 1 |Tr-rTT^' Tl | t T r I 1 -^0 SALINITY 31 32 33 34 5 10 15 X (— Q. 20 UJ Q 25 30 35 40 P^ o FREQUENCY OF DIVIDING 2 3 4 5 6 7 ' I ■ ' ' ■ I ' ' ' ' I ' ■ ' ' I ' ■ ' ' I ■ ' ' ■ t ' ■ SPECIFIC ACTIVITY 0 5 2 3 4 5 6 7 8 - \ -"^ 10 - 15 I 1— Q. 20 UJ Q 25 -O 30 - 35 4n - TEMPERATURE 123456789 10 I ' ' ' ' I ' ' ' ' I ' ' ' ' 1 ' ' ' ' 1 ' ■ ■ ■ I ■ ' I ' I ' ' ' M ' ' ' ' I ■ ' ' ■ I 30 10 15 I h- 0.20 UJ Q 25 30 33 40 SALINITY 31 32 — I — ^-~y — ' — ' — r — 33 34 I Figure 5b. The vertical distribution of thymidine incorporation (pmoles 1 ' h'),bacleria(10''cellsl'), frequency of dividing cells {% of total bacteria), specific activity of thymidine incorporation (10-' moles cell ' h '), temperature (°C). and salinity CVm) at Stations 1 00 and 104 (BSHW's). 70 15-1 10- -t-i O D m a) -1 1 1 1 1 1 1 r- — I 1 r- 10 ^5-, Specific Activity IS . c) 10 ■*-> U o m O/' a CO -e- ■8 -> I I I I I — I — I — I — I — 1 — I — r — I — I — I — 1 — I — I — I — I — f— ' — I 1 2 3 4 5 6 7 8 9 10 11 12 Temperature 15 10 o u D b) 0 / / /. 0 0/ 0/ ^- ii. £i -^A A A .iP ^ 15 10 -t-> o D m -T — r- 10 I 15 Specific Activity d) 0 A 0 / 0 / ^ir ^ / 0 / '^aO 0 / aO A A A A 0 0 -\ — r—1 — I — I — I — I — I — I — I — I — I — I — I — I — I — I — 1 — I — I — I — I — I 1 2 3 4 5 6 7 8 9 10 11 12 Temperature Figure 6. Linear regression of bacteria plotted against specific activity (a.b) and temperature (c,d ), Fig. 6c shows data from ACWs (circles) and AWs (squares), and Figs. 6b and 6d show data from BSHW's (triangle) and BSW's (diamond). Statistics for linear regressions are given in Table 2. 71 TABLE 2 Statistical analysis for linear regressions of plots in Figs. 5 and 6. Variable abbreviations: Thy (thymidine incorporation), Bac (bacteria), T (temperature), and Spa (specific activity of thymidine incorporation) are the parameters for the regression analysis. Statistics Abbreviations: F-value (value for data variance), r- (correlation coefficient), C.V. (coefficient of variation). Intercept (y-intercept). Slope (slope of the best linear regression), T-test (test of null hypothesis (Ho), Slope >0). Anadyr Waters Regres. F value r- C.V. Intercept Slope T-test Thy*T 5.6 0.23 22.7 1.94 -0.058 0.03 Thy*Spa 8.8 0.33 21.3 1.09 0.092 0.008 Bac*T 0.1 <0.01 29.3 3.44 0.015 NS Bac*SPA 26.2 0.59 18.7 5.11 -0.322 0.0001 Alaskan Coastal Waters Reeres. F value C.V. Intercept Slope T-test Thy*T 33.4 0.64 22.7 -0.56 0.887 0.0001 Thy*Spa 0.5 0.03 37.9 1.14 0.056 NS Bac*T 6.5 0.26 34.7 0.17 1.625 0.02 Bac*Spa 10.7 0.37 32.2 6.00 -0.564 0.004 Bering Shelf Waters Regres F value C.V. Intercept Slope T-test Thy*T 3.2 0.15 47.3 1.04 0.169 NS Thy*Spa 6.2 0.25 44.2 0.50 0.347 0.02 Bac*T 1.6 0.09 40.1 3.93 0.315 NS Bac*Spa 1.8 0.09 39.9 6.91 -0.507 NS Bering Sea water Regres. F value r- C.V. Intercept Slope T-test Thy*T 98.2 0.82 70.1 -0.92 0.418 0.0001 Thy*Spa 23.4 0.51 114.1 -0.21 0.797 0.0001 Bac*T 79.2 0.78 46.4 -1.37 1.433 0.0001 Bac*Spa 8.4 0.27 84.5 1.87 2.038 0.008 lower than Anadyr and ACW" s (T-test. P < 0.05 ). The specific activity again was unrelated to frequency of dividing cells (T-test, P> 0.05). Bering Sea water: The highest rates of thymidine incorporation and numbers of bacterioplankton were measured in the surface mixed layer of the south Bering Sea (Fig. 6). Incorporation rates ranged from 5 pmole 1 ' h ' above the thermocline to less than 1 pmole 1' h ' below the thermodine and less than 0.2 pmoles 1 ' h ' below 100 m. Rates were strongly correlated with temperature and specific activity (Fig. 2, Table 2). However, this strong relation could be attributed to any number of factors (e.g., phytoplankton productivity or biomass in the upper mi.\ed layer). Surface mixed layer processed the highest number of bacterioplankton (1 x 10" cells 1 '), and numbers decreased to less than l-2x 10'*cellsl' below l()()m(Figs. 5a,b). Likewise, bacteria correlated strongly with temperature and specific activity (Fig. 3, Table 2). Surface waters also had the highest frequency of dividing cells (4 to 7% dividing), but frequency of dividing cells decreased with depth to less than 2% dividing below 500 m (Fig. 6). At Station 1 10, bacterioplankton showed a secondary peak in dividing cells at 1 ,500 m, and below 2,000 m dividing cells increased with depth to nearly 12% dividing cells. Specific activity showed a similar distribution to frequency of dividing cells in the water column. In the mixed layer, specific rates averaged 2.5 x 10-' mole cell ' h ' (Table 1) and decreased to 0.1 1 X 10 -' mole cell ' h ' below 500 m. At Station 1 10, both specific activity and the frequency of dividing cells increased with depth below 1,500-2,000 m. At Station 113, specific activity, but not frequency of dividing cells, increased with depth below 1,500 m (the old GEOSECS Station). Spatial Distribution of Bacterioplankton In the Chirikov basin, bacterioplankton dynamics showed considerable variability through the water column and across the water types. The regional depth distribution of bacterioplankton parameters are summarized in Table 1 . In nutrient-rich AW, the highest rates of thymidine incorporation occurred in the surface and near bottom waters. Bacterioplankton, frequency of dividing cells, and specific activity, generally covaried with the rates of thymidine incorporation, even though the water column was isothermal. In nutrient-poor ACW, the thermocline was generally a dynamic region in the water column for bacterioplankton activity. Bacterioplankton, thymidine incorporation, frequency of dividing cells, and specific activity peaked within the region of the thermocline at water depths of 10-20 m, whereas in BSHW, the upper mixed layer contained highest bacterioplankton activity. Like BSHW, the highest bacterioplankton activity occurred in the upper mixed layer in the deep waters of the south Bering Sea. Below the thermocline, bacterioplankton uptake of thymidine diminished greatly even though measures of population growth rate increased with depth in bottom waters. In these deep waters, bacterioplankton populations were an order of magnitude or two lower than upper mixed layer. Comparison to other Marine Ecosystems Thymidine incorporation data reported here for Chirikov basin and south Bering Sea (0.0 to 4.7 pmoles 1' h') fell within the range of values reported for other coastal-shelf waters and adjacent and marginal seas in both high and low latitudes of the Northern and Southern Hemispheres. In polar waters of McMurdo Sound and the ice edge zone of the Ross Sea, Antarctica, where temperatures range from -1.8 to 5°C year round, Fuhrman and Azam (1980) found similar rates of thymidine incorporation of 0.2 to 1 1 .3 pmoles 1 ' h"' (calculated from values in Table 1, Fuhrman & Azam, 1980). Within the Antarctic Polar Front (2.5°C) of the Drake Passage, rates were also on the order of 0.1 to 10 pmoles 1 ' h ' over the upper mixed layer, but within the productive marginal ice edge zone (-1 to 2°C) off the Palmer Peninsula, rates as high as 200 pmoles 1' h ' were measured (Hanson & Lowery, 1983). In northern latitudes off Nova Scotia, Canada, Douglas et al. (1987) found thymidine 72 incorptiration rates ranging from 1 .4 pinoles 1 ' h ' in coastal waters with temperatures of 6.5°C to rates of 4.7pmoles 1 ' h ' at the shelf break with temperatures of 7.5-1 0°C. In the Celtic Sea where water-column temperatures varied from 8 to 15°C. thymidine rates ranged from 0.24 to 0.81 pmoles (values converted from data given in Table 3 in Joint & Pomroy. 1983). In coastal shelf waters off NW Spain with temperatures of I0-I8°C, rates of 0.1 to 10.1 pmoles 1' h' were reported (Hanson ei al., 1986a; Hanson et al.. accepted). In other temperate waters, rates ranged from 0. 1 to 20 pmoles I ' h ' for California Coastal waters (calculated from data in Table 1 in Fuhrman ct al.. 1980) and for southeastern US shelf waters (Hanson t-i al., 1988). Therefore, results from the Chirikov basin and surface waters of the south Bering Sea show that bacterioplankton during this late summer period appeared as productive as bacterioplankton on many continental shelves and oceanic ecosystems in northern temperate and southern polar regions. Bacterioplankton are the most abundant group of marine organisms in pelagic communities, yet the least understood in regard to population structure, function, and interaction with other pelagic communities in marine food webs. Total bacterioplankton counts varied little with water type on the north Bering Sea Shelf (overall 4.2 x 10"! 0.2 [S.E.J cells 1 ' ). The highest density of bacterioplankton occurred in the surface waters ofthe south Bering Sea (about 1.3x 10''cells I ')■ These densities are quite similar to values reported for other polar or subpolar regions (Fuhrman & Azam, 1980, 1982; Hanson et al., 1983; Garrison et al.. 1986; Pomeroy & Deibel, 1986; Douglas et al.. 1987; Kottnieier & Sullivan, 1987). Estimate of Bacterioplankton Productivity and Growth Rate.s Because of the uncertainty in the proportion of bacterioplankton that use thymidine for DN A synthesis relative to total metabolically active cells ( Douglas c/t//., 1987), we can only estimate the productivity of the bacterioplankton in the Bering Sea ecosystem. Our estimates are based on a theoretical conversion factor of 2 X 10"* cells produced (mole of thymidine incorporated) ' (Fuhrman & Azam, 1982), the accuracy of which depends on a number of assumptions that have been discussed previously (Fuhrman & Azam, 1982; Ducklow & Hill. 1985; Douglas e/rt/., 1987). Empirically derivedCF'sgenerally range 1 to5x lO'^cells produced (mole of thymidine incorporated) ' (Kirchman «'?«/., 1982; Riemann et al., 1984, 1987; Ducklow & Hill, 1985). Acknowledging the relative accuracy ofthe theoretical CF. we applied the theoretical CF and report the productivity of the bacterioplankton in the Chirikov on the order of 1 -5 x I O*" cells produced 1 ' h ', average 3 x 10" cells 1 ' h ' (Table 3). These rates of cell productivity in the Chirikov basin are on the same order as rates measured in other high and low latitude ecosystems. In McMurdo Sound and the Ross Sea. Antarctica, Fuhrman and Azam ( 1980) estimated cell productivity rangmg from<(). 1 to 21 X 10" cells 1' h' (rates adjusted 1.54 times; a theoretical CF of 1.3 x 10"* cells (mole of thymidine incorporated] ' was originally applied to thymidine incorporation for cell productivity estimates). TABLK 3 Bacterioplankton production (mg carbon m - d '), bioinass (g carbon m -), growth rate (u, d '). and doubling time (Ln 2/u,days) in the Chiriko\ basin and south Bering Sea. August 1 988. Bacterioplankton production based on estimates from thymidine (Thy) incorporation and frequency of dividing cells (FDC). N Production Biomass Growth Doubling Thy FDC Rate Time Anadvr Waters 2(J 263 835 1.48 0.18 3.8 Alaskan Coastal Waters 20 223 623 1.08 0.21 3.3 Bering Shelf Waters 20 245 1050 1.82 0.14 4.9 Bering Sea Waters (upper mixed laver) 6 387 1770 3.00 0.13 5.3 Dividing-cell productivity by the total number of bacterioplankton, an estimate of the specific growth rate of bacterioplankton population can be calculated. Specific growth rates in the three water types in the Chirikov basin are given in Table 3. Growth rates were not significantly different across the basin. Rates averaged 0. 1 8 day ' ( or a population doubling time of roughly 5 days). The doubling time of 5 days is similar to the doubling times reported for temperate coastal and shelf waters ( 1 to 4 days, Fuhrman & Azam, 1982; 4 days. Joint & Pomroy. 1983; 0.8 to 10 days, Hanson et al., 1986b, 1988). Assuming a thymidine-active subpopulation of 50% ofthe total number of bacterioplankton in the Chirikov basin, the doubling time of this subpopulation is 2.5 days. The doubling time of the thymidine-active bacterioplankton in Canadian Shelf waters off Nova Scotia ranged from 0.5 to 1.2 days (Douglas et al., 1987). Thus, mean growth rate for bacterioplankton of high latitude ecosystems are in general comparable to rates calculated for bacterioplankton in low latitude environments. Hagstrom et al. ( 1979) proposed a frequency of di\'iding cells (FDC) method to estimate bacterioplankton growth rates without incubation and radioactive organic substrates. Theoretical consideration and empirical evidence have shown that the frequency of cells in the dividing state is proportional to the growth rate ofthe population ( Newell & Christian, 1981; Larsson & Hagstrom, 1982; Hanson ('/«/., 1983). Tocalculate growth rates by the FDC technique, a basic assumption is that all cells are metabolically active. But because of inactive cells in the population. FDC values underestimate the growth state of the active population. Thus, estimates of bacterioplankton growth rates using FDC error conservatively. 73 The FDC values in this study ranged from 1 to 1 2% of the ceils dividing (averaged 4%). not much different from values reported elsewhere. Using the empirical relationship between FDC and specific growth rate, u (In u = 0.81[FDC]-3.73), (Hanson ef «/., 1983), for southern ocean bacterioplankton. we calculated a specific growth rate of 0.58 day ', a doubling time of 1.7 days. Growth rates estimated from the FDC method in the Chirikov basin were generally lower than those made from thymidine incorporation. A similar conclusion was made by Riemann ('/ al. (1984), although Newell and Fallon (1982) found lower results for thymidine incorporation compared with FDC. The results shown here for thymidine incorporation and FDC procedures indicate doubling times between 2 and 5 days. Correcting for inactive cells, bacterioplankton growth rates probably range on the order of 1 to 3 days during the late summer period in the Chirikov and south Bering Seas. In summary, bacterioplankton carbon production in the Chirikov basin and the surface waters of the south Bering Sea was estimated based on an average carbon content of 10 fentograms carbon per cell (Fuhrman & Azam, 1980). From thymidine-based cell productivity estimates, bacterioplankton production averaged 245 mg C m - d ' in the Chirikov basin and 387 mg C m - d ' in the upper mixed layer of the south Bering Sea (Table 3 ). Frequency of dividing cells- based production was 2 to 5 times the thymidine-based estimates (Table 3). The large difference between both estimates is attributed to the relative accuracy of the theoretical conversion factor and the empirically derived FDC equation. Thus, a comparison of bacterioplankton production and phytopiankton production in the Chirikov and south Bering Seas suggests that bacterioplankton production ranges between 5 and 33% of the phytopiankton production (Table 4). If we assume that the average growth yield of marine bacteria is about 50% of the organic matterconsumed, then bacterioplankton in these waters may consume upwards to 70% of the total phytopiankton production, but it is probably much less. Future bacterial studies need to evaluate the incorporation of thymidine into cellular components, growth kinetics, active cells, and empirical relationships of thymidine incorporation and frequency of dividing cells. The uiithors ihank the US Fish ,ind Wildlife .Service (USFWS) and Division of Polar Programs (NSF) for traveUi lid shipping assistance and Mr. Steven Kohl (USFWS) for logistical arrangements that TABLE 4 Comparison of bacterioplankton and phytopiankton production (mg carbon m - h ') in the Chirikov basin and south Bering Sea. August 1988. Bacterioplankton production estimated from thymidine incorporation and frequency of dividing cells (see Table 3). Bacterioplankton Phytopiankton Production Production Anadyr Waters (0-40 meters) 10.9-35.6 Alaskan Coastal Waters (0-35 meters) 9.3-25.9 Bering Shelf Waters (0-40 meters) 10,2-43.8 Bering Sea Waters (0-30 meters) 16.1-73.8 175 Percent Bacterioplankton 6-20 209 221 5-21 7-33 9-74 175-221 5-^^ allowed the authors to participate in the Third Joint US-USSR Bering & Chukchi Seas Expedition. Mr. Harold J. O'Connor (USFWS), the US Project Leader, and Dr. Alia Tsyban, the USSR Project Leader, represented the bilateral US-USSR Environmental Agreement under Activity 02.07-2 1 0 1 . Dr. Terry Whitledge and Dr. Alia Tsyban acted as chief scientists for the Americans and Soviets on the Soviet's RA' Akadcmik Korolcv. The authors acknowledge the cooperation and assistance of the captain, crew, and Soviet scientists during the research cruise aboard the RA' Akademik Korolev. 74 4.1.3 Bacterial Production and Destruction of Organic Matter VASSILIY M, KUDRYATSEV, VLADIMIR O. MAMAEV*. and TAMARA F. STRIGUNKOVA* ^Institute of Global Climate and Ecoloi;y. Stale Committee for Hydrometeorology and Academy of Sciences, Moscow. USSR 'Bach Biochemistrs- Institute and the Academy of Sciences, Moscow, USSR Introduction Bacteria play an important role in mineralization and detoxication of anthropogenic materials (e.g., oil hydrocarbons, pesticides, anionic surfactants, and heavy metal compounds) (Larsson & Lemkemeier, 1981; Tsyban, 1981; Bernard & George, 1986;Braginsky, 1986; Sahasrabudhe& Modi, 1987; Tsyban f/«/., 1987d; Kirsof/«/., 1988; O'Connor & Huggett, 1988). While considerable data have been published on the processes and mechanisms of organic matter destruction, the extent of biological self-purification have not been studied thoroughly enough, especially in subarctic and arctic areas of the World Ocean. In these regions, characterized by low temperatures and increasing anthropogenic load, the role of microbial transtomiationofcontaminants becomes considerably more important. In this regard, the assessment of bacterial production, destruction of organic matter, and the transfonnation of toxic organic compounds of anthropogenic origin is very important to determine the assimilation capacity, self- purification of organic contaminants, and prognosis of marine ecosystems. Materials and Methods The production-destruction process affected by bacteria in the Bering and Chukchi Seas was studied in July-August 1988 during the third Soviet-American ecological expedition. Bacterial production and the rate of organic matter (OM) destruction was measured in the Gulf of Anadyr, Bering and Chukchi Seas (Fig. 1 ). Dark CO, assimilation was measured by the Romanenko and Kuznetsov ( 1 974) method. Details are given in Methodical Foundationsof Integrated Ecological Monitoring of the Ocean ( Tsyban ef«/., 1988) and Kuznetsov and Dubinina( 1989). To determine dark CO, assimilation, water samples were taken from standard hydroiogical depths with Niskin bottles and added to 100-ml stoppered bottles. The bottles were tilled in the same way as samples taken for soluble oxygen (i.e.. Hushed with 3 water volumes). The bottles, filled with water, were placed in dark sacks and 0.5 ml of NaV CO,(specific activity about 20 X Kfcounts/min) were added. Bottles were stoppered without air bubbles under the stopper. Duplicate samples were taken from each depth. Two reference bottles were included at each station and, apart from radioactive sodium carbonate, 1 ml of 40% fomialdehyde solution was added. Bottles inside the sack were tightly closed to light and incubated at surface seawater temperature. BactenjI Decomposition produclion 1 of organic matter 0.5g CIm- BJ per l.Og Clttt • Station number 36 S^^ ^35 d1 .19 Fig. 1 . Bacterial prttductitin and dcctMiipttsitnin olarganic matter in the 0.5 to 4,'^ m layer in the Gulf of Anadyr, and central Bering Sea. summer, 1988. After suitable exposure, depending on temperatures, formalin ( I ml ) was added to each bottle. Water samples were filtered through a "Sinpor" membrane filter having pore diameter 0.35 or 0.45 |Jm and immediately treated with 1 '7c hydrochloric acid to remove residues of radioactive carbonate. Radioactivity was measured by means of liquid scintillation. Dark COj assimilation was calculated by the following formula: c = Cffe ■ Rxt where r = ^catl, ~ R = dark CO, assimilation, |ig C/l/d; radioactivity on filters, dpm/min; carbonate contents in the water, mg C/1 (determined by direct titration with 0.1 HCl in the presence of methyl red tracer); isotope added to each bottle, dpm/min; incubation time. 24 hours 75 Bacterial production was calculated by the fomiula Pb =:Q.x16.6, where Pg = bacterial production, |ag C/l/d; Q, = quantity of 14 CO, assimilated, |ig C/l/d; 16.6= relationship of total biomass carbon and biomass synthesized from carbon dioxide (100:6). To assess mineralization processes of organic matter, biochemical oxygen demand ( BOD) is usually used. In practice, BOD is more often determined after 24 hours of exposure under in situ conditions. Presently, there is no single and reliable technique for BOD determination. "Bottle" technique over-estimates the oxygen demand of bacteria and is labor intensive. Apart from that, the effectiveness of the oxygen technique in eutrophic waters to determine destruction of organic matter in waters with low temperature and primary production is difficult. In mesotrophic and oligotrophic waters, the radioisotope technique is extensively used to measure destruction of organic matter which is more sensitive and less labor intensive. The application of this technique is due to the relationship between oxygen demand and heterotrophic assimilation of CO, by bacteria (Romanenko, 1965), where 7 mg C/CO, is assimilated per mg of oxygen used for bacterial respiration. Hence, there is a coefficient to determine the quantity of oxygen consumed by bacteria relative to heterotrophic assimilation of CO,. Oxygen used by bacterial respiration was calculated by the formula where O, = Ct = 7 = O, = Cj/l. oxygen deinand for organic matter destruction, mg 0,/l/d; dark CO, assimilation, |ag/l/d; Coefficient between oxygen demand and CO, assimilation. Results and Discussion Bacterial Production and Organic Matter Destruction in the Bering Sea The change in bacterial numbers and biomass does not determine their biological state and role in marine ecosystems. These questions can be assessed by means of a sensitive radiocarbon technique to measure the bacterioplankton respiration. The data obtained in summer 1988 (Table 1) show considerable variance in the rate of bacterial production (1.5-135 |ig C/l/d) and destruction of organic matter (4.8^35.0 |ig C/l/d). Production in the Bering Sea averaged 17.3 ng C/l/d or 28.4 fig C/m'. The destruction of organic TABLE 1 The rates of bacterial production and destruction of oraanic matter in the Berins Sea in summer 1988. Investigated sea areas Bacterial production Organic matter destruction P/B Hg C/l/d gC/m- ngC/yd g C/m- Benna Strait 8.0-28.9 0.7 25.7-92.7 16.4 52.7 2.4 1.1 Northern 8.2-29.2 0.8 26.2-97.7 Bering Sea 17.6 56.5 (Chirikov basin) 2.5 1.0 Anadyr Bay 1.5-33.7 6.4 0.9 4.8-108.2 20.7 2.9 0.4 Central Bering Sea 1.5-44.8 8.9 1.3 4.8-144.1 28.5 4.1 0.5 East Polygon 4.3-118.5 33.4 100.2 13.8-380.9 107.3 321.9 2.3 South Polygon 2.0-135.5 22 2 66.6 6.4-435.5 71.2 213.6 2.1 Total for the Sea 1.5-135.5 17.3 28.4 4.8-435.5 55.7 91.2 1.2 matter averaged 55.7 |ig C/l/d or 9 1 .2 fig C/m-. These rates are 20 times higher than similar estimates obtained in summer 1981 and 1984 (Tsyban et al., 1987a). These rates also equalled production and destruction processes in mesotrophic marine ecosystems (Sorokin, 1980). High rates of bacterial production and destruction of organic matter occurred in eastern and south Bering Sea (e.g.. East and South Polygons). Maximum rates, found at Stations 3 and 108, averaged 47.8 and 153.7 |ag C/l/d, respectively. Low rates of bacterial production occurred between 0.5—15 m at Stations 5 and 109, where rates averaged 8.3 and 1 5.8 ng C/l/d, respectively. Rates of organic matter destruction at these stations averaged 26.8 and 50.9 |ig C/l/d. These rate processes in 1988 are 10 times higher than those measured in 1981. The rates of bacterial production and organic matter destruction varied considerably across the eastern and south Bering Sea areas (Table 1). Thus, southern and eastern Bering Sea were characterized by high but variable rates of bacterial production and organic matter destruction across the basin. A high production/biomass (P/B) coefficient was also obser\'ed in eastern Bering Sea (Table 1 ). In the central basin and in the Gulf of Anadyr, low rates of production and destruction occurred even though the total numbers of bacterioplankton in these areas were higher than in the southern and eastern Bering Sea (Tsyban et a!. , Section 4. 1 , this volume). The rate of bacterial production and organic 76 matter destruction in euphotic zone averaged 8.4 |ig C/l/d, and 26.9 )ig C/l/d, respectively. Lower rates occurred in the Gulf of Anadyr. Maximum activity of microflora and high rates of bacterial production of 25.5 and 18.7 |ag C/l/d and organic matter destruction of 8 1 .9 and 60.0 |.ig C/l/d were found at Stations 7 and26(Fig. I; Subchapter4. 2.1, this volume). The lowest rates of bacterial production of 4.2 and 2.8 |ig C/l/d and organic matter destruction of 13.4 and 9.1 |ig C/l/d were found at Station 6 in the deep central part of the Bering Sea, and at Station 1 1 in the Gulf of Anadyr. These results are similar to those obtained for stratified waters in the vicinity of frontal zone of the Irish Sea (Turley & Lochte, 1985). The results showed that the highest rates of bacterial production and organic matter destruction occurred in the surface microlayer and near-bottom waters in the deep central basin of the Bering Sea, higher than rates measured in the zone of phytoplankton photosynthesis. In Gulf of Anadyr, rates gradually decreased with depth, and in bottom waters, rates of bacterial production and organic matter destruction were two times lower than in the surface microlayer. In general, the central part of the Bering Sea and Gulf of Anadyr were characterized by the low bacterioplankton activity, the low rates of bacterial production and organic matter destruction, as well as by low production/biomass coefficient. Because of its distinct hydrological and hydrochemical characteristics, the northern part of the Bering Sea is much different in other areas in the sea. Shallow depths, intensive water exchange and unstratified water column produced a uniform distribution ofbacterioplankton and microflora activity. The rates of bacterial production and organic matterdestruction were high (Table 1 ) in this part of the sea. The average daily rate was about 18|igC/l. Organic matterdestruction amounted to about 56.6 |ig C/1, which is about 3 times higher than in the Gulf of Anadyr. Integrated over the water column, the rate of bacterial production was 0.8 g C/m- and destruction of 2.5 g C/m-. The highest microflora activities and diurnal rates of bacterial production of 12.1 |ag C/l/d or 0.85 g C/m- were found at Station 96 and the lowest rates at Station 92. The rate of organic matter destruction at Station 96 was 68.0 |ig C/l/d or 2.7 g C/m-, whereas at Station 92 destruction was two times lower (Fig. 2; Subchapter 4.2.1, this volume). The distribution of microflora activity in the Chirikov basin was independent of the uniform distribution of bacterioplankton. The rates of bacterial production and organic matter destruction in the surface microlayer decreased with depth. The daily rate averaged about 20 fig C/1 of bacterial biomass in the surface microlayer while organic matter destruction averaged to 65. 1 |ig C/l/d. Thus, the shallow waters of the northern Bering Sea was characterized by high rates of bacterial production and organic matter destruction, the integrated rates being much lower than in deep water areas of the sea. In addition, microflora activity varied horizontally and vertically, and P/B coefficient averaged 0.97 in the northern Bering Sea. Bacterial r— i Decomposition production H of organic master 0.5g C/m 2 ■-I per l.Og C/nT • Station number CHUKCHI PENINSULA I ^'°° n M I. 104 Fig. 2, Bacterial production and decomposition of organic matter in the 0.5 to 45 m layer in the northern Bering Sea, summer 1988. In summary, this investigation of microbiological processes in the Bering Sea allowed us to assess the scales of some links in production and transformation of organic matter. It was shown that CO, assimilation by heterotrophic microorganisms contributes to the production of organic carbon in the system. Microflora contribution to the total production via CO, fixation is sufficiently high and can amount to about 30% of the primary production. In addition, microflora contributes to the destruction of organic matter. The rate of destruction processes was determined based on the activity of bacterial population, trophic ability level, and hydrological and chemical conditions in the Bacterial Production and Organic Matter Destruction in the Chukchi Sea The rates of bacterial production and organic matter destruction were measured in the Chukchi Sea for the first time. The results (Table 2) show that a relatively high rate of production and destruction occurs in the water column. The average rate of bacterial production was about 20 \ig C/l/d, or 0.8 g C/m-. The rate of organic matter destruction was about 64.9 ng C/l/d, or 2.5 g C/m-. These rates are slightly higher than those in the Bering Sea. They agree with the rates of production and respiration in mesotrophic waters, such as temperate seas, regions of equatorial divergence, upwelling areas where daily production of bacterioplankton biomass varied from 5 to 20 |ig C/1 and respiration from 10 to 60.0 |ig C/1 (Sorokin, 1985). Based on microflora activity, rates of bacterial production, organic matter destruction, and bacterial respiration, some areas in the sea differed from other areas. The highest microflora 77 TABLE 2 The rates of bacterial production and organic matter destruction in the water column of the Chukchi Sea. summer 1988. Investigated sea areas Bacterial production Organic matter destruction ^gC/l/d gC/m^ |ig C/l/d gC/m= Northern part of the Sea 2.2-46.5 16.7 0.7 6.9-149.5 53.6 2.4 Coastal Alaska Area 2.0-20.6 11.0 0.3 6.4-65.9 3.54 1.0 Central part of the Sea 7.9-66.9 26.8 1.1 25.2-214.8 86.4 3.4 Coastal Chukotka Area 7.9-61.3 26.2 1.0 25.2-196.6 84.3 3.2 Total for the Sea 2.0-66.9 20.2 0.8 6.4-214.8 64.9 2.5 activity was found in the central basin of the Chukchi Sea ( Fig. 3; Subchapter 4.2.1. this volume ). In coastal waters of the Chukchi, rates of bacterioplankton production and organic matter destmction averaged 2-3 times higher than the rates of production and organic matter destruction in Alaskan Coastal waters. The daily rate of bacterial production averaged 26.8 ng C/1 or 1.1 g C/m-; bacteria respiration rate was 86.4 ]Xg C/i or 1.3 g C/m-; P/B coefficient was 1.3. A low microflora activity was observed in coastal areas of Alaska. Diurnal rates of bacterial production averaged 0.3 g C/m-, respiration rate 1 .0 g C/m', and P/B coefficient was the lowest, 0.5," measured in the region. Although the rates of bacterial production and organic matter destruction varied in the water column, microflora activity and organic matter destruction gradually increased from surface layers towards the bottom of the water column. Bactenal production (I5g C/m- i\ DcLomposition of organic matter per l.Og C/rrr Station number P Jl:^ iCIU {? CHUKCHI \ PENINSULA Fig. 3, Bacterial production and decomposition of organic matter in ttie 0.5 to 45 m layer of the Chukchi Sea, summer 1988. In the northern Chukchi Sea, rates of bacterial production in layer 25^5 m were 1.7 times higher than rates measured in water layer 0.5-25 m. Total production of bacterial biomassin bottom waters averaged 27.8 |ig C/l/d, while in euphotic waters production was 20 |ig C/l/d. In conclusion, the study of microflora and microbiological processes in the Chukchi Sea allowed us to identify specific features of formation and function of microbiocenoses in this Arctic Sea. In addition, the activity of microflora and rates of bacterial production was determined and the role of bacterioplankton assessed in the transformation of organic matter. The results showed that the rates of bacterial production and organic matter destruction in the Chukchi Sea equaled rates in mesotrophic waters. 78 Subchapter 4.2: Heterotrophic Saprophytic Microflora 4.2.1 Distribution of Indicator Groups of Marine Heterotrophic Microorganisms ALLA V. TSYBAN, GENNADIY V. PANOV, and SVETLANA P. BARINOVA Natural Environment and Climate Monitoring Laboratory and Academy of Sciences, Moscow. USSR Introduction Over the last few decades, the attention over ocean pollution has become one of the most urgent problems in applied oceanography and is drawing great attention by world scientific communities (Goldberg, 1970; Bemhard & Zattera, 1975; Izrael & Tsyban, 1981, 1985a, 1989; Pravdic, 1981; Gesamp, 1982; Kullenberg, 1984). Today's anthropogenic impact on the World Ocean creates a tense ecological situation. Pollutants are becoming not only a continuously active ecological factor (Izrael & Tsyban, 1985), but also an evolution factor by affecting sea organisms (Izrael & Tsyban, 1989). Pollutants getting into the sea environment, including xenobiotics, cause rapid change in sea organisms and, due to directional selection, result in active growth of certain hydrobionts and disappearance of others that are not able to tolerate the action of foreign substances. Organisms, which have adapted to new chemical compounds that pollute the sea environment and then take a dominant position in the biocenosis structure, are named after the chemical substance. There are grounds to suggest that the development of these hydrobionts is a function biological response to the chemical pollutants of the world's oceans (Izrael & Tsyban, 1981, 1985a, 1989). Biological significance of indicator types is determined by their special designation. Some fill a critical gap in biocenoses, others help to restore the natural backgrounds while still others determine the immunity of the sea ecosystem (Izrael & Tsyban, 1989). The latter include sea microorganisms. Microorganisms have high rates of reproduction and extensive range of constitutive and inductive enzymatic activity. The latter characteristic stipulates their ability to transform and utilize practically all naturally occurring organic compounds. For this reason, these organisms are distinguished for their unique ability to rapidly adapt to changing environmental conditions. For example, an accidental oil spill in the world's oceans would result in rapid and abrupt increase of hydrocarbon oxidizing bacteria by 3-5 orders of magnitude (Gunkel, 1968; Atlas el ai, 1976; Le Petet et ai. \911: Oppenheimer et ai. 1977; Atlas, 1981). The possibility of using microorganisms that are capable of oxidizing oil as indices of the degree of hydrocarbon oxidation under natural conditions and indicators of oil pollution was shown in the 1950's (Izjurova, 1950; Voroshilova & Dianova, 1950. 1952). According to Voroshilova and Dianova (1950, 1952), the number of oil-oxidizing bacteria in clean pools did not exceed 1 00 cells/ml, and in 50% of the cases, less than 10 cells/ml. Another parameter used as an index of the degree of water pollution with oil products is the ratio of the numbers of oil-oxidizing to heterotrophic bacteria (Voroshilova & Dianova, 1950; Gavrishova, 1969; Mironov, 1970). Atlas (1981) used the ratio between oil oxidizing microorganisms and total bacterial number as an index of oil pollution. The concept of using microbes as indicative of organic pollutants in the World Ocean has been most actively developed during the last 20 years. Itwas shown (Tsyban ef a/., 1985)that, depending on the phenomena under consideration, microbial cenoses may act not only as indicators of physicochemical and biological processes but also as a powerful biotic factor, facilitating pollutants' elimination from the sea environment. At present, physiological and biochemical potential of microbial populations is at the stage of active developments. However, these important fields of marine microbiology have not investigated the distribution in different parts of the World Ocean or with depth of heterotrophic bacteria using or transforming various organic substances. Bacteria using high- molecular toxic compounds (e.g., benzo(a)pyrene [BaP] and polychlorinated biphenyls [PCB's]), are an important characteristic of the world ecosystems state under the conditions of increasing anthropogenic influence. Materials & Methods Investigations of indicator microflora in the Bering Sea began in 1981 (Izrael et al., 1987) and continued during the period of the Second Joint US-USSR Expedition on board the research vessel (WW ) Akademik Korolev in 1984 (Izrael etai, 1988; 1989; 1990). These investigations were continued in 1 988 during the Third Joint US-USSR Bering & Chukchi Seas Expedition on the Akademik Korolev. It should be noted that in 1 988 observations were carried out not only in the same areas of the Bering Sea as in 1981 and 1984 but also covered some new areas: the Gulf of Anadyr, the Chirikov basin, the Bering Strait, and the southern part of the Chukchi Sea. All together, 82 stations were studied in the Bering Sea and 3 1 stations in the Chukchi Sea. Water samples from the near-surface microlayer 0-2 cm thick were taken with sterile water microsamplers, with sterile bottles, or with plastic Niskin Water samplers, presterilized with 96% ethanol. These samples were immediately analyzed to reveal indicator bacteria, including the following forms: saprophytic bacteria (SB), hexadecane oxidizers (HDB), benzo( a)pyrene transformers ( BaPB ), and polychlorobiphenyl transformers ( PCB B ). The detennination of bacterial indicator groups is viewed as a study of physiological activity of indigenous sea microflora prior to their isolation from the habitat. 81 Numbers were determined by the method of ultimate dilutions, described as early as 1927 by Razumov (1927), which is widely used in similar works (Gunkel, 1967; Atlas, 1981; Platpira, 1982, 1985; Shtukova, 1990). The method consists of adding into two to three rows of test tubes, containing a liquid medium or "sea potassium-yeast medium" (SPY). These media were supplemented with hexadecane, BaP, or PCB as the only source of carbon. Dilutions were made in measured volumes of analyzed seawater so that the initial sample in the first test tubes was diluted 1:10, and followed by 1:100, 1:1,000, 1:10,000 (etc.) times accordingly. After incubation, test tubes were checked for maximum dilution of the sample that showed growth of the bacterial physiological group understudy. Growth was determined visually by change in transparency and color of the medium. A special statistical McCredy table was used to determine the numbers of bacterial cells per milliliter. When using the method of ultimate dilutions, we assumed that the observed bacterial growth occurred when at least one actively dividing bacterial cell was transferred during inoculation. To study SB. fish broth made with seawater from investigated areas was used as a liquid medium, prepared from 0.5 kg of fish cooked in 1 liter of water, and diluted 10 times with the same seawater. The medium was poured into test tubes and sterilized in an autoclave with pressure 1 atm (1.01 X 10' Pa) for 20 minutes. To determine the number of other indicator bacteria groups, a liquid SPY medium was used (Tsyban, 1970; Seki, 1986) containing K.HPO^ (1 g), NHjCl ( 1 g), yeast extract (0.5 mg), and seawater ( 1 ,000 ml). These media were poured into test tubes and autoclaved. Sterile substrate, hexadecane, BaP, PCB, or Aroclor 1232 (0.01-1%) was added into test tubes after inoculation. The SPY medium, as an elective media, has found extensive application in the practice of marine microbiology ( Seki, 1 982; Tsyban etai, 1985; Izrael & Tsyban, 1989). The statistical method of prismatic ecograms was used to analyze the results (Tsyban, 1970). Results and Discussion Saprophytic Bacteria in the Bering and Chukchi Seas In the central Bering Sea (East Polygon), the MPN of SB varied within the range of 0-1.8 x 10' cells/ml, 222^40 cells/ml for the investigated stations. These bacteria varied with depth at Stations 1, 2, and 3 of about 3,000 m deep. Maximum concentrations of more than 1,000 cells/ml occurred at depths 10-25 m (thermoline), 150, 500, and 2,500 m. The above bacterial groups were not discovered at Station 1, 15 m and 3,000 m; at Station 2. 2,000 m; Station 3, surface microlayer; or Station 4, 25 m. At shallow-water stations ( Stations 4 and 5 ), SB increased only in deep-water and near-bottom layers of waters deeper than 100 m. Such distribution of microflora reflected water masses heterogeneity in this sea area. Compared to 1984 (Izrael c? a/., 1988; Tsyban el al., 1990), the number of SB at East Polygon remained constant (0-10'' cells/ml), but their vertical distribution varied with depth. In the northwest Bering Sea at the sections near St. Lawrence Island, SB distribution was also variable. Maximum concentrations ( 10' cells/ml) occurred at depth and in the near bottom layers of Stations 7, 18, and 19. Overall, the vertical distribution of this group of microorganisms showed an increase in numbers with increase in depth. At Station 36, not far from the St. Lawrence Island, the SB (10- cells/ml) remained constant over the entire water column from 1 5 m to the bottom. At other stations SB in the upper layers of water (0, 5, and 10 m) ranged from 10' to 10' cells/ml. Distribution analysis of mean SB number showed that maximum mean MPN values were typical for Station 7 (2.4 X 10' cells/ml). At other stations of the section (with the exception of Station 35), mean values for saprophytes varied between 105 and 360 cells/ml. At Station 35, the SB mean was about 96 cells/ml. First studies of microflora of the Gulf of Anadyr were made during this cruise. Numbers varied across a very wide range from zero to 1.8 x 10^ cells/ml. Maximum values occurred at Stations 24 and 27. At Station 1 1, SB did not range greatly — 0-300 cells/ml. mean 56 cells/ml. At Station 41, situated between the Gulf of Anadyr and Chirikov basin, SB averaged 7.1 x 10' cells/ml. Vertical distribution of saprophytes was variable, with a trend towards increasing concentration with depth (Fig. 1 ). In the Chirikov basin and Bering Strait, SB varied vertically and horizontally. Overall, concentrations ranged between 0 and 1.8 x 10' cells/ml. At Stations 96, 100, 102. and 104. cell ?f 27 Sialion No MPN, tcll5/ml 1 . 11-100 2-101-1000 CHUKCHI 'i^^ peninsula! 'l •.. I • '' •32 • 36 •l^ \ • 22 •35 •l3 •,5 • 19 • 10 • / b) C>7 T?f MPN. <:cllf,/ml 1 ■ 1-10 CHUKCHI T"-^ PENINSULA L 3- 101-1000 •3^#^' ^ • 27 < •24 3e.t \ •22 •55 •13 •,5 •,9 • 7 d) Fig. I. Vertical distribution of mean values of the most probable number (MPN) of heterotrophic-saprophytic (a), hexadecane oxidizing (b), benzo(a)pyrenc transforming (c) and PCB-transforming (d) bacteria at stations in the northwestern Bering Sea and the Gulf of Anadyr in summer 1988. 82 numbers averaged 10- cells/ml, and at Stations 89, 92, and 104, numbers averaged 10' cells/ml. At Station 102, in the southeastern part of the basin, SB averaged only 1 70 cells/ml, but near the Alaskan shore (Station 92) we found the largest concentrations (4.4 x 10' cells/ml) in the Bering Sea. In the deep Bering Sea (South Polygon), SB ranged from 0 to 1.8 X 10' cells/ml, but mean values (per station) were higher, 1.3-2. 6 X 10' cells/ml. Compared to 1984(Izraelc/^j/., 1988; Tsyban er ai. 1990), the numbers of SB increased slightly. In 1984, they were within the range of 0-3. Ox lO'cells/ml. Themean values were also higher in 1988 than in 1984. Distribution of these bacteria varied over water column depth. Saprophytic microflora in the near-surface microhorizon (0-2 cm thick) were absent or in extremely low numbers at Stations 108, 1 10, and 1 12. In summer 1988, the first microbiological survey in the southeastern Chukchi Sea was made. The area was characterized by two large sources of biogenous elements. Here, inorganic nitrogen compounds were being advected through the Bering Strait and along the coastal Siberian Current. Biogenous elements also originated from the Chukchi and Alaska Rivers. Through the combination of these flows, a wide area with high rates of primary production of organic matter by phytoplankton, was fonned in the southeastern Chukchi Sea. In the process of photosynthesis, phytoplankton excrete newly synthesized organic matterthat is substrate forbacterioplankton. Extensive growth of phytoplankton is usually accompanied by increased numbers of SB (Gocke, 1977; Rheinheimer, 1977, 1985). Indeed, our results show that the numbers of SB were higher in the Chukchi Sea than in the northwestern and northern parts of the Bering Sea. The number of SB varied between 1.8 and 2.0 x 10^ cells/ml, with averages between 0.4 and 16.6 X 10' cells/ml. Highest mean numbers of SB occurred in the coastal zone of Alaska (Station 66, 1 1.2 x 10' cells/ml; Station67, 16. 6x 10' cells/ml). High mean numbers of SB also occurred at Station 55, 10.3 x 10' cells/ml. At other stations in the Chukchi Sea, mean values varied between 0.4 X 10' cells/ml (Station 74) and 9.6 x 10' cells/ml (Station 57; Fig. 2). Vertical distribution of bacteria varied little over depth. At Stations 50, 55, 61, 67, and 69, SB distribution remained constant with depth and varied by no more than one order of magnitude at Stations 50, 61, and 69 ( 10--10' cells/ml). At other stations, SB varied by 2-3 orders of magnitude. The largest variation was observed at Station 49 (3-1.8 X 10-* cells/ml). Analysis of SB in the Bering and Chukchi Seas Relative to Temperature and Salinity During the time of expedition in the Bering Sea, water temperatures varied from - 1 .6°C to + 1 0. 1 °C and salinity ranged from 29.73% to 34.64%. For analysis, we grouped samples to both temperature and salinity (Fig. 3a). In the Bering Sea, 27% of the water samples fell in the temperature range between -2 and +2°C; 40% between +2 and +6°C; and 33% between +6 and + 10°C. The waters of the Chukchi Sea, in comparison with the Bering Sea, was colder. The majority of samples (65% ) fell within the temperature range between +2 and -i-6°C, and only 10% of samples had temperatures exceeding +6°C. • • dj y n-100 '01 1000 MF'N ^eWilmi /" ALASKA .^ • ^' • W52k >3 •e, •"•\ p.,^ 69* 67© #66 CHUKCHI PE.N1NSULA \*72 •74 •75,^ ■f K *( ALASKA r^ e Fig. 2. Vertical distribution of mean values of saprophytic (a), hexadecane oxidizing (b),BaP-transforming(c), and PCB-transforming(d) bacteria at stations in the Chukchi Sea in summer 1 988. Numbers near symbols are station numbers. N«IO cells/ml 6 — I Fig. 3. Occurrence rate (%) of samples with various combinations of temperature and salinity in pairs in the Bering (a) and the Chukchi (b) Seas in summer 1988. and mean values of heterotrophic saprophytic bacteria number in the above samples from the Bering (c) and Chukchi (d)Seas. Number of bacteria are 10' cells/ml. 83 In the Chukchi Sea, waters appeared less saline (24.04 to 33.66%) than the Bering Sea, and only 5% of the stations had salinities greater than 33%. Salinities less than 29.70% were included in the 29.70-31.35% for analysis (Fig. 3b). In the Bering Sea, the highest mean number of SB (3.7 X 10' cells/ml) occurred in warm waters, with temperatures +6°C and salinity between 33.00 and 34.65%, which represented a small percentage (3%) of the total number of analyzed samples. These samples dominated the surface 25 m in the southern Bering Sea (South Polygon and Station 1 13). Water samples from the Bering Sea with temperatures higher than 6°C and salinity 3 1 .3 1-33.00% represented 25% of samples. These samples were usually taken from the surface 25 m in the central, northwestern, and northern areas of the sea and contained about 8.0 x 1 0- SB cells/ml ( Fig. 3 ). Mean values of SB number with other pair combinations of temperature and salinity grouped close to each other, 1.0 to 3.7 x 10' cells/ml (Fig. 4). In the Chukchi Sea, the highest mean number of SB (1.15 x 10^ cells/ml) also grouped in relatively warm waters (> + 6°C), but in contrast to the Bering Sea, less saline waters (>31.35%). The lowestmeannumberofSB(5.7x 10- cells/ml) was similar to other pair combinations of temperature and salinity, 4.7 to 6.0 x 10' cells/ml (Fig. 3). Ecogram analysis showed that during the cruise in the Chukchi Sea, the saprophytic microflora grew rapidly as maximal mean SB in the Chukchi Sea (1.15 x 10^ cells/ml) occurred in warm, low salinity waters, typical of southeastern water (Stations 65 and 66). An area affected by river flow from the Alaska coast (Fig. 2). Hexadecane-oxidizing Bacteria in the Bering and Chukchi Seas The most probable number of HDB in the central Bering Sea, East Polygon, in summer 1988, varied between 0 and 1.8 X 10' cells/ml. Maximum numbers occurred only at Station 3', at depths of 45 and 150 m. At other stations, HDB varied less— 0-30, 0-180, and 0-300 cells/ml. In the South Polygon, HDB ranged between 0 and 180 cells/ml at Station 1 12 (average 90 cells/ml). At the other stations, HDB ranged from 0-1.8 x 10' cells/ml (averaged between 180 and 700 cells/ml). Samples with maximum HDB represented >10% of the total number of samples in this deep- sea area (Fig. 4). This bacterial group varied vertically. The greatest vertical variation occurred at a station nearest the St. Lawrence Island, where HDB increased with depth, with practically no hexadecane-oxidizing microflora in the near surface microlayer. Mean numbers of HDB in the section ranged between 10 and 100 cells/ml. Only at two stations. 7 and 19, did DB numbers exceed 10- cells/ml. Generally, in the southeastern Bering Sea, including the Gulf of Anadyr, HDB varied between 0 and 1.8 x 10' cells/ml. Hexadecane-oxidizing microflora occurred in 72% of the samples. Fig. 4. Occurrence rale ['~i ) of various value.s of the mosl probable number (MPN, cells/ml ) of heterolrophic saprophytic and other functions of groups in the Bering and Chukchi Seas in summer 1988: (a) southern Chukchi Sea; (b) northern Bering Sea (Chinkov basin) and the Bering Strait; (c) the Gulf of Anadyr; and (d) central and southern Bering Sea. In the Chirikov Basin, HDB also varied between 0 and 1.8 X 10' cells/ml, averaging between 10 and 100 cells/ml. HDB increased at Station 83 in the Bering Strait and at Station 89 (Fig. 5). In general, the HDB distribution in the Chirikov basin resembled the distribution in the open sea (Fig. 4). In the Chukchi Sea, HDB varied between 0 and 1.8 X 10"* cells/ml. Their distribution appeared extremely variable. Thus, at Station 66, only a few cells/ml occurred, while at Station 49, they ranged up to 3.4 x 10' cells/ml (Fig. 2). Generally, HDB occurred in 62% of the samples, but at only 1 0 cells/ml ; waters that are characteristic of nonpolluted seas (Fig. 4). A relatively high number ( 10- cells/ml) of HDB occurred in 2 1 % of the samples. This may be explained by the fact that microorganisms of this group also use aliphatic hydrocarbon as a source of carbon and energy. The source may be anthropogenic, but aliphatics also seep into the sea from underwater oil fields, and are synthesized and subsequently released by some seaweed. Prismatic ecogram analysis (Figs. 6,7) showed that the largest mean numbers of HDB (7.1 x 10- cells/ml)in the Bering Sea occurred in waters with high concentration of SB; that is, waters with relatively high temperatures (>6°C) and salinities (>33%) (Fig. 6). Such combinations of temperature and salinity occurred in only 3% of the total number of analyzed samples (Fig. 6). However, the numbers of hexadecane- 84 Fig. 5. Vertical distribulion of mean values of saprophytic (a), hexadecane oxidizing { b), BaP-transfomiing (c ). and PCB-transforming ( d) bacteria at stations in the northern Bering Sea (Chirikov basin) in summer 1988. oxidizing microflora were also high in waters with temperatures <6°C, but with relatively high salinity (>33%) (Fig. 6). In the Chukchi Sea, the highest mean number of DB (6.6 X 10- cells/ml) (Fig. 7) were found in waters with temperatures between +2°C and +6°C and salinity between 31.35% and 33.00%. Such conditions occurred in 60% of all the samples (Fig. 7). This analysis of hexadecane-oxidizing microtlora in the waters of the Bering and the Chukchi Seas confirms that these waters remain relatively unpolluted. The waters of the northern, central, and especially southern areas of the Bering Sea have experienced aliphatic hydrocarbon inputs of natural or anthropogenous origin. Benzo(a)pyrene Transforming Bacteria in the Bering and Chukchi Seas Mean numbers of BaPB in the northwestern Bering Sea, includingtheGulfof Anadyr, averaged about lO'ceils/ml. The highest concentration of BaPB occurred at Stations 24 and 27 near the coastal zone and at Station 41 between the Gulf of Anadyr and the Chirikov basin (Fig. 1). The vertical distribution of BaP-transforming microflora followed a similar distribution for hexadecane-oxidizing microflora. However, in the Chirikov basin, high mean numbers of BaPB were not only found at Stations 83 and 89. but also at Stations 86 and 104 (Fig. 5). Similar numbers occurred in the Chukchi Sea (Fig. 2). In the central and southern Bering Sea, BaPB varied between 0-3.0 x 10"" cells/ml, but most often values fell between 10 and 100 cells/ml (28%^ of all the samples) and 100-1,000 cells/ml (29% of all the samples), respectively N. celli/ml 500—1 Fig. 6. Occurrence rate (R,%) of samples with various pair combinations of temperature and salinity in Bering Sea in summer 1988 (a), and mean numbers of hexadecane oxidizing (b). BaP-transforming (c). and PCB-transforming (d) bacteria (cells/ml) in the above samples. (Fig. 4). As for BaPB distribution, the open waters in the central and southern Bering Sea differed from other areas. Here, 40% of samples possessed low BaPB numbers, whereas only 11% of samples contained more than 1,000 cells/ml (Fig. 4). Water samples with relatively high temperatures (>6°C) and salinity (>33%) in the southern Bering Sea again contained the highest mean numbers of BaP transforming microorganisms, 8.9 x 10- cells/ml (Fig. 6). In the Chukchi Sea, highest mean numbers of BaPB (6.0 x 10- cells/ml) occurred in water samples with relatively low salinity (<31.35%) and temperatures between 2°C and 6°C. Such conditions exist in the surface waters at Stations 45 and 59, a coastal area affected by the Siberian rivers outflow, and at Station 53 in Alaska Coastal waters ( Figs. 2,7). Compared to 1 984 and, as far back as 1 98 1 , the number of BaP-transforming microflora in the Bering Sea in 1988 has increased at a number of stations, and their distribution has become more extensive. Polychlorinated Biphenyls-transfonning Bacteria in the Bering and Chukchi Seas In 1981, research in the Bering Sea began on the number and distribution of heterotrophic bacteria that transform PCB's and has continued in summers 1984 and 1988. At the East Polygon, in the central Bering Sea, the PCBB varied between 0 and 180 cells/ml. Maximal concentration, 3.0 X 10' cells/ml, was measured at only 150 m at Station 1. The distribution of this bacterial group varied with depth, but 85 peaked at 0.5- 1 0 m, i 50-200 m, and 1 ,500 m at the deep-water stations. At shallow-water Stations 4 and 5. highest concentrations occurred at 0.5, 15, and 45 m. Compared to 1984, the numbers of PCB-transforming bacteria had not increased and their vertical distribution remained constant (Fig. 8). Vertical variations of PCBB in the northwestern Bering Sea resembled the distribution of both hexadecane and especially BaP-transforming bacteria. Maximum numbers of PCBB (10- cells/ml) occurred in near-bottom waters. At Station 7, which is the farthest from St. Lawrence Island, only 10 cells/ml were measured. At Station 35, the density of PCB-transforming bacteria increased to 180 cells/ml at 25 m. Fig. 7. Occurrence rate {9c) of samples with various pair comhinations of temperature and salinity in the Chukchi Sea in summer 1988 (a) and mean valuesof numbers (cells/ml ) of hexadecane oxidi/mg (b), BaP- transformmg (c). and PCB-transformina (d) bacteria. The horizontal distribution of PCBB in the northwestern Bering Sea, including the Gulf of Anadyr, was highly variable. Mean numbers ranged between 1 and 10 cells/ml at Stations 32 and 36; 1 1-100 cells/ml at Stations 7, 9, 10, 13, 19, 27, and 35; and 101-1,000 cells/ml at Stations 24 and 41 (Fig. 1). The variation of PCBB was generally greater than for HDB, but similar to the BaP-transfonning microflora (Fig. 1 ). Compared to 1981, the numbers of PCBB in 1988 increased 2-3 times, from 100 cells/m in 1 98 1 to 1 80 and 300 cells/ml in 1988. The distribution of PCBB also became more extensive in 1988 (Fig. 9). Stations 16(B) Fig. 8 Vertical distribution of PCB-transforming bacteria in the central Bering SeatEast Polygontsummer 1984 and I98X. The insert shows location of stations. 1 10 100 1000 Fig. 9 Vertical distribution of PCB-transforming bacteria at three stations of North Polygon in the northern Bering Sea near St. Lawrence Island in summer 1981. 1984, and 1988. X - axis = station numbers and indices of stations; and Y - axis = depth (m). In the Chirikov basin and the Bering Strait, PCBB varied between 0 and 180 cells/ml. with 39% of all the samples containing 180 cells/ml (Figs. 4,5). Due to significant vertical variability, mean numbers for the various stations never exceeded 100 cells/ml. Only at Station 83 in the Bering Strait, the mean number of PCBB averaged more than 100 cells/ml, ranging from 180 to 690 cells/ml. Distribution of PCBB showed high numbers at 0.5, 45, 250, and 2,500 m. In the southern Chukchi Sea, PCBB also varied between 0 and 3.0 x 10' cells/ml (Fig. 2), but concentrations most often fell within the range of 10-100 cells/ml in 29% of all the samples (Fig. 4a). Although the mean numbers of PCB-transforming microflora ranged between 10 and 1,000 cells/ml (Figs. 2,6), PCBB at 6 out of 1 8 stations under investigation rarely exceeded 100 cells/ml. At the remaining 12 stations, PCBB fell within range of 10 and 100 cells/ml (Fig. 2). In the Chukchi Sea, 10% of samples contained PCB-transforming microflora with more than 10' cells/ml (Fig. 4a). These bacteria were absent in 16% of all those analyzed whereas, in the Bering Sea, as much as 30% of the samples had no PCBB (Fig. 4). PCB-transforming bacteria showed similar distribution ecograms as other indicator groups in the Bering Sea. Maximum mean numbers of PCB-transforming bacteria (7.4x 10- cells/ml) occurred at stations with high temperatures. 86 6-10°C, and salinities >33% in surface water. In the Chukchi Sea, the ecograms differed between Stations (Fig. 7). The largest mean number of PCBB (8.8x1 0' cells/ml ) again found in the waters with salinities of 3 1 .35-33.009; and temperatures >6°C (Fig. 7). The resemblance of ecograms between the Chukchi and Bering Seas (Fig. 6) indicates the variety of functional groups that exist in these seas and that these groups are widely distributed and comprise an integral part of the ecosystem. These ecograms illustrate again the variability and patchiness of these groups in these seas. In summary, from the results on the number and distribution of saprophytic, hexadecane-oxidizing. BaP- and PCB- transforming bacteria in the Bering and Chukchi Seas, and comparison with investigations conducted in 1981 and 1984, we found: /. In the summer of 1988, SB were ubiquitous, albeit highly variable, in the Bering and Chukchi Seas. In the Bering Sea, these bacteria occurred most frequently at hundreds of cells/ml, whereas in the Chukchi Sea, they exceeded 10' cells/ml. Based on boreal concentrations of SB. the Bering Sea can be characterized as oligomesotrophic and the Chukchi Sea as mesotrophic. 2. Hexadecane bacteria were also highly variable in the Bering and Chukchi Seas. In the Bering Sea, maximum numbers changed little since 1984 and were most abundant in the Bering Sea (South Polygon) where significant concentrations of anthropogenic hydrocarbons occurred. 3. Benzo(a)pyrene-transforming bacteria were also variable in the Bering and Chukchi Seas. These bacteria were widely dispersed in the Chukchi Sea, generally at lOcells/ml. Although the distribution of BaP-transforming bacteria was also patchy in the Bering Sea (the Chirikov basin, the Bering Strait, South and East Polygons), BaPB were most abundant at 1 00 cells/ml. 4. PCB-transforming bacteria covaried with the distribution of BaP-transfomiing bacteria. 5. Relative to 1981 and 1984, numbers in each functional group and their distribution increased significantly in summer 1988. suggesting that the Bering Sea ecosystem is experiencing anthropogenic inputs. 6. From characterizing the number and distribution of each functional bacterial group ( in particular. PCB-transforming bacteria) in the Bering and Chukchi Seas, we conclude that there exists an anthropogenous effect on the ecosystems. The degrees of entrophication varies with each region. In the central Bering Sea, as well as in the Gulf of Anadyr, anthropogenic impact is minimal. However, in the northern Bering Sea and in the southern Chukchi Sea, anthropogenic influences are evident. Because of the remoteness of the area from big industrialized centers, the presence and distribution of PCB- and BaP-transforming bacteria indicates the global propagation of organic pollutants via atmospheric processes. 4.2.2 Taxonomic Composition of Heterotrophic Bacteria ALLA V. TSYBAN\ GENNADIY V. PANOV\ SVETLANA P. BARINOVA, VLADIMIR I. IVANITSA', and GALINA V. KHUDCHENCO= 'Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences. Moscow, USSR ^Odessa State University. Odessa, USSR Introduction Methods and Materials The study of the morphologic characteristics and taxonomic composition of microorganisms of the Bering Sea was started in 1 98 1 and 1 984, and continued in 1 988 during the Third Joint US-USSR Bering & Chukchi Seas Expedition. In 1988, investigations included microbial structure (microbial population including taxonomic diversity ) of the Chukchi Sea. It is noteworthy that these microbiological investigations were conducted over extensive areas of the Bering and Chukchi Seas and that they included the taxonomic determination of heterotrophic bacteria that were isolated from different sites of the marine environment. The taxonomic investigation included 829 strains of bacteria isolated from different sites of the marine environment (the water column, bottom sediments, and biota): 432 strains isolated from the Bering Sea in summer 1981; 320 strains isolated from the Bering Sea in summer 1984; and 77 strains isolated from the Chukchi Sea in 1988. In addition, the results are compared to bacterial cultures isolated from the Baltic Sea impact region of the World Ocean. Bacteria from the marine environment and their culture were isolated using fish broth and fish peptone agar prepared with fresh seawater(Tsyban. 1980). The inocula were incubated at 28°C. 87 To characterize the cultures according to morphologic and phenotypic traits, generally accepted methods were used (Gerhardt, 1983; Yegerov, 1983). Taxonomic position of the strains was investigated using the schemes of marine Gram- negative bacteria and the 8th edition of Bergey's determinant (Shewanc/fl/., 1960;Pallroni, 1975; Sieburth, 1979;Buchanan & Gibbons, 1982; Oliner, 1982). Results and Discussion The morphology of 432 isolates of heterotrophic microorganisms from the Bering Sea environment in 1981 showed that rods accounted for 81.4% of the bacterial representatives. The cocci accounted for 18.6% of the isolates (Table 1 ). The length and width of the rods ranged from 0.7 to 2.0 and from 0.3 to 1. 5 |im, respectively. Their diameter varied from 0.5 to 1.5 |im. Most bacterial isolates (87.4%) possessed mobility (see Table 1 ). Peritrichs and monotrichs accounted for 74.5% and 25.5%, respectively. The presence of spores was found in 82 of 297 isolates, which accounted for 27.6% (see Table 1 ). For comparison, among 66 isolates from the Baltic Sea in 1982, the cocci were far less than in the Bering Sea, only 4.5% of the investigated isolates. The rest, 95.5%, were motive peritrich rods (see Table 1). The number of spores formed (13.6%) in the composition of Baltic microflora were also lower than in Bering Sea fiora (see Table 1 ). One of the most important morphologic and systematic traits of microorganisms is affinity to the Gram Stain. The test of 297 isolates from the Bering Sea bacteria showed that most isolates (70.8%) were Gram-positive; the remaining 29.2% were Gram-negative. It is interesting to note that among 66 isolates from the Baltic Sea, 60.5% of microorganisms were Gram-negative, and only 39.5% were Gram-positive (see Table 1 ). Visual pigments occurred in 59.2% of 432 bacterial isolates from the Bering Sea. Pigmentation of Bering Sea isolates ranged from white to red: 16.9% pink; 1 1.8% creamy; 9.3% yellow; 5.6% beige; 3.7% grey; and 14% red. One isolate formed brown colonies. Investigations of Baltic cultures showed that, unlike Bering Sea cultures, most isolates (60.6%) formed colorless colonies. Among these colonies, only 4 isolates were distinguished: 25.7% white, 9.1% beige. Most of Bering Sea isolates (67.2%) dissolved gelatine, decomposed peptone (9%), and formed ammonia. Others (12.64^) induced a change in protein molecules and formed hydrogen sulphide. Indole was also formed by 36.6% of the TABLE 1 Morphologic traits of the isolates of heterotrophic bacteria from the Bering and Baltic Seas in 1981 & 1982, respectively. Morphologic trail BermgSea. 1981 Baltic Sea, 1982 Number Number % Number Number % of of of of isolates isolates with determined morphologic traits isolates isolates with determined morphologic traits 432 81 18.6 66 3 4.5 432 351 81.4 66 63 95.5 297 82 27.6 66 9 13.6 432 377 87.4 66 63 95.5 432 55 12.6 66 3 4.5 297 210 70.8 66 26 39.5 297 87 29.2 66 40 60.5 Cocci Rods Presence of sporification Motile forms Immotile forms Gram-positive Gram-negative Pigmentation of colonies Absence of pigment Pigments: pink creamy yellow white beige brown black 432 176 40.8 66 40 60.6 432 73 16.9 66 - - 432 51 11.8 66 4 6.1 432 41 9.4 66 3 4.5 432 39 9.0 66 17 25.7 432 24 5.6 66 6 9.1 432 1 0.2 66 - - 432 - - 66 2 3.1 88 1 97 isolates studied. Nitrates were reduced to nitrites by 37.9% of cultures. Half of the isolates fermented glucose, and 13.5 and 23.2% of the isolates produced acid and gas. respectively. Only 3% of the isolates produced a significant amount of gas. In addition, of all the strains studied in the Bering Sea, 80.7% possessed catalase activity, 54.8% oxidase, and 29% lecithinase activity. The presence of lipase was found in 40.9% of 332 isolates (see Tables 2,3). It is noteworthy that while studying the physiological properties of bacteria isolated from an impact region of the World Ocean — the Baltic Sea — significant distinctions were found as compared with the bacterial populations of the Bering Sea, a background region of the World Ocean. For example, unlike Bering Sea isolates, 25.7% of Baltic microorganisms formed ammonia in the decomposition of peptone (see Table 2). In addition, Baltic isolates (on a percentage basis) possessed a greater ability to ferment glucose. lactose, and mannitol than that of Bering Sea isolates, and to produce gases (15.0%). Specific enzyme assays show that 80.7% of Bering Sea isolates possess the catalase activity (80.7%) slightly more than Baltic isolates (59.0%). On the other hand, oxidase(83%) and lecithinase (42.3%) activity proved to be typical of a greater percentage of Baltic isolates as compared to the Bering Sea. Similar results were found in 1984 for bacteria isolates from different localities in the Bering Sea. Taxonomic characteristics of 200 isolates from 1981, and 320 isolates from different sites of the Bering Sea were also determined on the basis of morphology and physiology. The results are presented in Table 4. The genera most prevalent were Bacillus (27.5%), Bacterium (22.5%), Pseudomonas (18%) and Platwcoccus ( 1 3.5%). These genera accounted for 81.5% of the number isolated from the sea. TABLE 2 Physiological properties of the isolates of heterotrophic bacteria from the Bering and Baltic Seas in 1981 & 1982, respectively. Physiological properties Bering Sea.1981 Baltic Sea, 1982 Number Number % Number Number % of of of of isolates isolates with determined traits isolates isolates with determined traits Break down of gelatine 332 224 67.2 Formation of ammonia glucose 432 225 52.2 66 54 81.5 lactose 432 58 13.5 66 21 31.7 mannitol 432 100 23.2 66 35 53.0 Formation of catalase 432 348 80.7 66 39 59.0 oxidase 432 236 54.8 66 55 83.0 lecithinase 432 125 29.0 66 28 42.3 lipase 332 136 40.9 - - - TABLE 3 TABLE 4 Distribution isolates from the Bering and Baltic Seas in 1981 and 1982 according to the basic enzymatic traits. Groups of bacteria Isolates possessing the above traits, % BerinaSea. 1981 Baltic Sea. 1982 Lactose positive Oxidase positive Catalase active 13.5 54.8 80.7 31.7 83.0 59.0 Taxonomic position of the isolates from the Bering Sea in 1981 and 1984. Isolated strains Genus in 1981 in 1984 Number 't Number % Pseudomonas 36 18 86 26.8 Xantomonas - 5 1.7 Bacillus 55 27.5 75 23.4 Bacterium 45 22.5 54 16.9 Planococcus 27 13.5 57 17.8 Aerococcus 2 1 3 0.9 Alcaligenes T 1 7 2.2 Halohaclerium - 2 0.6 89 These genera also dominated in 1984, accounting for 84.9% of the total number. However, the relative number of the genera Bacillus and Bacterium was somewhat less, while the numbers of the genera Planococcus and especially Pseudomonas increased. Generally, pigmented forms dominated (93.3%) of all isolates. For the Chukchi Sea, isolates fell between bacterial populations of the Bering and Baltic Seas (Table 5). Here, isolates from the Chukchi Sea occurred over 1 1 genera: Pseudomonas. Xantomonas. Alcaligenes. Klebsiella. Aeromonas, and others (Fig.l). Taxonomic diversity of the dominating genera in the Chukchi Sea was somewhat less than in the Bering Sea ( 1 3 genera) but greater than in the Baltic Sea (9 genera). TABLE 5 Some morphological traits of Lsolates of heterotrophic bacteria from the Bering. Chukchi and Baltic Seas in % of the total number of the investigated strains. Morphologic traits Bering Sea Chukchi Sea Baltic Sea Cocci Gram-positive Gram-neaative 18.6 70.8 29.2 L\0 29.9 70.1 4.5 39.5 60.5 Thus, this comparative analysis suggests that a distinction occurs between the morphological, physiological, and taxonomic characteristics of bacterial isolates from the Chukchi Sea realtive to the Baltic (an impact region) and Bering (a background region) Seas. Only the index of relation between pigmented and nonpigmented forms does not comply with this assessment. Based on this analysis ( i.e., the number of bacillary and Gram-negative bacteria, taxonomic diversity, and number of Pseudomomis sp. ) the Chukchi Sea is specified as a region with a higher level of anthropogenic pollution. Pseudomonas Xantomonas Alcaligenes Halobactenum Aefomonas Flavobactenum' Staphylococcus Micrococcus Planococcus Aerococcus Bacillus Ailhrobacter Another Benng Sea Fig. I. Taxonomic positin of the strains of heterotrophic microorganisms of the Chukchi. Bering, and Baltic Seas. 90 Subchapter 4.3: Microbiological Transformation of Organic Matter 4.3.1 Transformation of Benzo(a)pyrene YURIY L. VOLODKOVICH and OLGA L. BELYAEVA Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow. USSR Introduction Microorganisms, distributed in the World Ocean, play a leading role in the functioning of these ecological systems and in biogeochemical cycles. Microflora is the most active component in these ecological systems (Izrael & Tsyban, 1982). Its biomass in the upper 1 00 m layer of the World Ocean reaches 25 x 10''GC/m-, which is similarto plankton biomass. While possessing functional enzyme systems and high biochemical activity, the microbial communities influence oceanic biogeochemical cycles of carbon. Many polycyclic aromatic hydrocarbons (PAH's) that are distributed in sea and ocean ecological systems possess toxic, mutagenic, and carcinogenic properties, which can manifest a clear threat to biotic components and possibly to human health. Microbial transformation of aromatic hydrocarbons and heterocyclic compounds has been well studied (Rodoff, 1961 ; Treccan, 1963; Bumpus, 1989). However, the rates of benzo(a)pyrene (BaP) transformation in seawateras well as the significance of this process in local and regional systems have not yet been studied. This paper reports on BaP transformation as a process that eliminates this dangerous compound from the sea. The investigations were conducted in the Bering and Chukchi Seas as part of an all-round investigation of PAH's that started in 1981 (Tsyban et ai. 1987d). Methods and Materials Studies on the transformation of PAH's were conducted at nine stations in the Bering Sea and in the southern part of the Chukchi Sea in August 1988. This cruise was the Third Joint US-USSR Bering & Chukchi Seas Expedition on board the research vessel Academik Korolev. Seawater was collected in sterile samplers. Surface microlayers was sampled with metal screens (0.02 mm). Water column was sampled with Niskin (depths: 0.5, 2 and, 10 m). Water samples with natural microbial communities were transferred in sterile glass bottles for microbiological studies on board ship. The rates of BaP transformation by natural bacterioplankton was conducted under //; situ conditions. Water samples of 250- ml volume was transferred into 500 ml dark glass bottles along with BaP dissolved in acetone. Four BaP concentrations were used: 100 and 20 |ig/l (10 days) and, 1.0 and 10 ng/1 (21 days). Abiotic factors were followed in sterile water from each depth with respective BaP concentrations. These experiments and controls were repeated 2-3 times. To simulate in situ conditions, samples were incubated on the ship's deck in running water for 10-21 days. To temiinate the microflora activity, a few milliliters of concentrated HCl were used. Residual concentrations of BaP were extracted in 250 ml of benzol and stored until analyzed. The BaP benzol extracts were olated and evaporated. The evaporated part of the benzol extract was eluted by 2 ml of solution of 1,12 benzapareline in octane (concentration 0. 1 mg/ml) and also used as an inner standard. The concentration of BaP in non-octane solution was determined by spectral and fluorescent analysis with the use of Shpolsky at 196°C on spectrographer C-12 (Shpolsky et al.. 1952; Fedoseevaera/., 1986). Sensitivity of the method was determined at 1 x lO'" g/ml + 10%. The rate was determined as the difference between the initial (artificially introduced) and final mass of BaP. Rates are expressed in percent of BaP transformed. Results and Discussion One consequence of PAH's circulation in the sea is its distribution relative to specific microflora that are adapted to new hydrochemical conditions and capable of transforming these dangerous compounds. Our results show that BaP transformation occurs in Bering Sea waters (Tsyban et al., 1987c ). During the 1988 cruise in the subarctic region of the Chukchi Sea, BaP transformation was again confirmed. The distribution of BaP transformers was patchy with numbers in the 0.5 m surface layer ranging from 10 to 1,000 cells/ml. The maximum density occurred in the Chirikov basin at Station 89 where more than 10' cells/ml were found. The potential activity of the microflora to transform BaP was studied in 10 //; situ simulation experiments. The results show that bacterioplankton from the Bering and Chukchi Seas possess the ability to transform BaP (Fig. 1). Microbial transformation of BaP varied from 8 to 5 1 % (Table 1 ) with little variation between replicates. The lowest transformation (2-3%), which is within experimental error, was found in the central part of the Chirikov basin. Comparison of 1984 and 1988 data (Fig. 1; Tsyban et al.. 1986; Izrael et al., 1987) shows that BaP transformation is relatively stable in the Bering Sea. At North Polygon, BaP transformations ( 1 0-day incubation ) were about 45-55% during these years. Considering the differences in experimental conditions, the results show that maximum biodegradation occurred in the 0.5 m level of the Gulf of Anadyr waters. The rate was 39 mg of BaP/1 over a period of 10 days. In the 93 BaP transfiirmalion in perceni fnim the onginal tonteniralion urtacc liiver 1984 .urfafc layer 1*^88 1988 Fig. 1 . BaP microbial transformation m experiments iii ,v;7h in the Bering and Cliuckchi Seas water (August, 1988). Chukchi Sea, maximum activity of microbial populations was found at Stations 45 and 50, where 25—45% of the BaP was transformed. The e.xperiments showed little differences in the amount of PAH's degraded by bacterioplankton in the surface microlayer and 0.5 m level (Table 1 ). In certain areas of the World Ocean, these processes are more pronounced in the surface microlayer. the zone of air-sea interaction (Tsyban, 1985). However, there is no direct correlation between the BaP content in sea waters and amount transformed. For example, low rates of BaP transfomiation occurred in waters with the highest concentration of BaP, 63 |lg/l at Station 29. To study the degradation of PAH' s at in situ concentrations ( 1 and 10 |ig/l), long in situ experiments were conducted up to 2 1 days. The results show that 54-57% of the initial BaP mass was transformed with the first 5-7 days (Table 2 ); after 2 1 days the process declined considerably. Maximum degradation was 67-85% of the initial concentrations. Similar results were found for concentrations of 1 and 10 |ig/l. The results from Stations 36 and 50 showed that despite local features of the BaP transfomiation (Table 1 ), bacterioplankton of the Bering and Chukchi Seas possess similar biodegradation potential. Transformation and removal of BaP in the surface layer occurred at a rate of 7 |ag/l over a period of 3 weeks. In summary, from the investigations performed in 1981. 1984, and 1988 in the Bering and Chukchi Seas, heterotrophic microflora exist in the waters, and the heterotrophic microflora show a pronounced biodegradation potential in relation to TABLE 1 Microflora transformation of BaP in the Bering and Chukchi Seas Water in in situ experiments of 10 days. August 1988. Region of Station Level of BaPc ancentration. BaP the works No., sampling Hg/1 Microbial date nitial Final transfor- C, Control Exper. mation. %C, East 3, 0.5 100 99.8 14.7 Polygon 28.07 0.5 100 100 85.3 91.5 8.5 The Gulf 7, Surtace 100 99.7 of Anadyr 01.08 microlayer Surface 100 81.5 18.5 microlayer 0.5 100 76.0 24.0 0.5 100 80.5 19.5 The Gulf 18, Surface 100 99.7 of Anadyr 03.08 microlayer Surface 100 93.9 6.1 microlayer 0,5 100 60.7 39.3 The Chukchi 45 Surtace 20 19.9 Sea microlayer 09.08 Surface 20 17.9 10.5 microlayer 0.5 20 9.7 51.5 (1.5 20 15.8 21.0 The Chukchi 50 Surtace 20 20.0 Sea microlaver 10.08 Surface microlaver 20 15.1 24.5 0.5 20 10.9 45.5 The Chinkov 89 0.5 20 20.0 basin 11.08 0.5 20 19.2 3.8 0.5 20 19,5 2.6 The Bering Sea 110 10.08 0.5 0.5 20 20 20.0 17.8 11.0 0.5 20 13.8 31.0 0.5 20 12,1 39,5 PAH's (Izrael ct a!., 1987). In addition, the rate of BaP transformation in the Bering Sea microflora is sufficiently high and similar to rates measured in the Baltic Sea (Tsyban et ai, 1985). Thus, the metabolism of PAH's by microflora should be considered as an essentially important process in the detoxication and remov al of pollutants from the ecosystems of the World Ocean. 94 TABLE 2 Dynamics of BaP transformation catised by the Bering and Chukchi Sea waters microtlora in long in situ experiments (Auaiist 1488). Region, Length of Original On ginal Station No. j,\position. concentration concentration days BaP = 1 .0 BaP = 10.0 |4 g/l/C, Hg/ i/c,„ BP transformation ng % from C| mg 9c from C|,i The Bering 0 0 0 0 0 Sea. North 7 0.31 31 4.21 42.1 Polygon. 10 0.59 40 5.47 54.7 Station No. 36 14 0.85 85 6.68 66.8 South-East 0 0 0 0 0 part of the 3 1.53 15.3 Chukchi Sea, 5 0.29 29 3.91 39.1 Station No. 53 7 0.52 52 5.70 57.0 10 0.80 80 7.12 71.2 14 0.81 81 7.64 76.4 :i 0.83 83 7.81 79.1 4.3.2 Transformation of Poly chlorinated Biphenyls by Marine Bacterioplankton ALLA V. TSYBAN, SERGEI M. CHERNYAK, and GENNADIY V. PANOV Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences. Moscow. USSR Introduction Pollution of biosphere, the World Ocean, by xenobiotics has become not only an ecological problem but a social problem. In the postwar years, production of synthetic organic compounds increased worldwide. In 1950, 7 million tons were produced — by 1970,63 million tons, and by 1983. 230 million tons(Geiss&Bourdeaux, 1986). At present, 5 million different xenobiotics are produced by chemical manufacturers, with fifty thousand being sold on the world market every year. No iTiore than 10% of synthetic compounds (of the total amount produced) are reportedly toxic and only twenty thousand xenobiotics have been studied for genotoxic activity (Loprieno, 1981; Tanabe, 1983). Most investigated chlorinated hydrocarbons are PCB's (Tanabe, 1983). This is due to wide application in industrial and domestic materials, resistance to biodegradation and bioaccumulation capability, acute toxicity, and unfavorable effect upon reproductive processes in pelagic organisms. Also, analytical techniques allow for reliable PCB determination in most environmental samples. Current predictions (Bletchly. 1984) on the dynamics of chlorinated hydrocarbons in the marine environment indicate that chlorinated hydrocarbon concentration in the World Ocean will increase 1.3-1.7 times by the year 2000. Because of the production of new synthetic substances and accumulation in the environment, scientists are interested in knowing the sources and fates of xenobiotics. At present, the elimination of PCB's from the environment occurs through photochemical oxidation and microbial degradation. Aspects of PCB biotransfortiiation need further study. In recent years, a great body of information has been ctiilected, transformation of PCB's by individual strains of microorganisms, relating to different systematic groups (Ahmed & Focht, 1973; Sayler et cd.. \911: Furukawa et ai. 1978; Furukawa et ai. 1979, 1983; Liu, 1980; Furukawa & Chakrabarty, 1982; Furukawa, 1982; Brunner ef «/., 1985; Unterman et ai. 1983; Bedard el ai, 1986; Bopp, 1986; Bedard et ai. 1987a, 1987b; Kohler et ai. 1988). Many bacteria have been shown toutilize PCB's as a source of carbon and energy (Karasevich, 1982;Shieldst7a/., 1985). However, not all PCB congeners are subject to microbial attack, which is 95 associated with the structure of PCB components. Thus, results from laboratory assays indicate that different PCB congeners are subject to different degrees of microbial attack and that each strain is capable of transforming a different spectrum of congeners ( Kohler et ai . 1 988 ). Because the World Ocean can be regarded as a reservoir of anthropogenic compounds, the assessment of PCB transformation in the marine environment is important. Our investigations of PCB microbial transformation under natural marine conditions were conducted during the Third Joint US-USSR Bering & Chukchi Seas Expedition. This work assesses biodegradation potential of PCB " s by isolated bacterial strains and natural marine bacterioplankton communities. Materials & Methods Experimental assessment of marine microflora biodegradation potential of PCB's was made on board the research vessel Akademik Korolev in July-August 1988. Overall, 12 assays (Table 1) were conducted in the eastern, northern, and southern parts of the Bering Sea, including the Gulf of Anadyr, the Chirikov basin, and the southern Chukchi Sea. TABLE 1 Characteristics of the regions of sampling when conducting experiments (see Frontispiece for location of Stations). Sea. Sampling Stations Experiment Water Salinity Region Number Temperature (%) °C Bering Sea, 3 1 8.8 32.60 East Polygon Bering Sea, 7 2 7.2 32.60 Gulf of Anadyr 18 3 7.3 31.16 22 4 6.5 31.46 Bering Sea, 35 5 7.4 30.91 North Polygon Chukchi Sea 45 6 2.3 24.04 50 7 6.1 31.66 53 8 4.4 31.09 55 9 5.3 31.56 69 10 -> 2 32.26 Bering Sea, 89 11 6.1 31.70 Chirikov basin Bering Sea, 110 12 9.6 32.94 South Polygon Niskin bottles (5-10 1) sterilized with 96° ethanol were used to collect samples from the upper ().5-m surface layer. Subsamples (200 ml) were drained into .500 ml dark glass bottles. These bottles were washed thoroughly, rinsed with acetone and hexane, and sterilized with dry heat at 200°C for 2 hours. For assay control, seawater from the same samples were sterilized by autoclaving at 1 atm (1.01 x 10^ Pa) for 30 minutes. Gas-liquidchromatography (Tuistra&Traag, 1983; Kohler et ai. 1988) was used to determine background PCB concentrations in 200-ml samples, which were always below detection. To determine the most probable number (MPN) of saprophytic (SB) and PCB-transforming (PCBB) bacteria, a dilution method was used (Tsyban et al., 1988). To determine the MPN of SB, a broth based on seawater from the various regions was used as the culture medium (see Subchapter 4.3). The medium was distributed into test tubes and sterilized by autoclaving. After inoculation, PCB solution was added into each test tube. Considering the distribution of PCB in the Bering Sea conducted in 1984 (Izrael & Tsyban, 1990), experiments were based on the use of PCB Aroclor 1 232 mixture, a composition similar to the PCB mixture found in the region. Each experiment was conducted with two series of test bottles: the first series with PCB concentration of 100 ng/1 and the second series of lOng/1. Each test was duplicated. Polychlorinated biphenyls solution in ethanol was added to control and test bottles and thoroughly shaken for 1-2 min and then incubated in the dark to prevent photochemical processes. The experiment was incubated under //; situ conditions (range 2-10°C) over the period of investigations. At 1,3,5, 10, 14, and 21 days, water (1 ml ) was taken from each test and control bottle to determine the MPN of SB and PCBB. Concentrated H,S04 ( 1 0 ml ) was added into each bottle to stop microbial metabolism. The amount of PCB remaining was determined by gas-liquid chromatography. Results and Discussion From the Aroclor 1232 experiment. 1 9 out of 70 congeners were transformed and those (Table 2) became the focus of the study. In the East Polygon in the Bering Sea, the percentage of individual Aroclor 1232 consumption, with an initial concentration of 100 ng/1, varied from 7% for hexachlorobiphenyls (Table 2) to 95-100% for dichlorobiphenyls (Figs. 1,2). Trichlorobiphenyls were also transformed, ranging from 64 to 90%. Degradation of pentachlorobiphenyls varied little, ranging 36-44% (Fig. 1, Table 3). Fortetrachlorobiphenyls, this group of Aroclor 1232 congeners can be divided into those that were readily labile over the 10-21 days, a biotransformation rate of 49-58% of the initial content, and those that were relatively stable, a rate of 10-18% of the initial content. Similar observations were revealed with an initial PCB concentration of 10 ng/1. Transformation of congeners, however, was more rapid, especially during the first 3 days (Table 3). Figure 1 a shows the change in number of saprophytic and PCB-transforming microorganisms with an initial PCB concentration of 100 ng/1. After the first day. the MPN of the bacteria did not increase over the initial numbers, but bacterial break down of PCB's continued. For dichlorobiphenyls, 40to 52% of these congeners (nos. 5,8, 15; Fig. lb) were transformed 96 TABLE 2 Systematic numbering of Aroclor 1232 congeners (Ballschmitter and Zell, mSO), and congeners subjected to transformation by bacterioplankton of the Bering and the Chukchi Seas. PCB- 100 Congeners Numbers Structure 5 8 15 Dichlorobiphenyls 2,3 2,4/ 4,4/ 18 22 28 31 Trichlorobiphenyls 2,2/,5 2,3.4/ 2.4,4/ 2.4/.3 40 44 47 52 60 66 70 77 Tetrachlorobiphenyls 2.3/3.3/ 2.2/.3.5/ 2,2/.4,4/ 2,2/5,5/ 2,3/.4,4/ 2,3/.4,4/ 2.3/.4/.5 3.3/.4.4/ 87 97 101 Pentachlorobiphenyls 2.2/.3.4.5/ 2.2/.3/,4,5 2.2/.4.3.5/ 153 Hexachlorobiphenyls 2.2/.4.4/5.5/ 21 days Fig. la. Most probable number of sapropliy tic bacteria (.SB, cells/ml) and PCB transforming bacteria (PCBB, cells/ml) in the first day. The same trend also occurred with an initial PCB concentration of 10 ng/l. In the first day, 70-73% of dichlorobiphenyls were transfomied (Table 3). Over the next 10 days bacterial numbers increased exponentially with both bacterial groups of SB and PCB reaching 1.8 x 10^ cells/ml (confidence interval, 2.7 x 10' to 1.2 X 10^ cells/ml). The percentage of transformation of PCB days Fig. lb. Microbial transtormalion of individual Aroclor 1232 congeners (%) in the experiments. In Experiment No. I. PCB initial concentration was at lOOng/l. Numbers are coherent numbers, see Table 2. Samples collected from the Bering Sea. East Polygon (Station 3). tV-ww»iv.5Ji.« Control, initial composition of PCB 1 SI day t 18 A \ 8 10 15 -^wV A A jm K 3rd day 1 8 5 7 AX 8 K 10 15 , V 5th day 1 18 7 8 A \° J 1 -"VA, J\Ml^ V Fig. 2. Microbial transformation of Aroclor 1232 (congeners numbers 5, 8, 15; see Table 2 ) in the central Bering Sea, Station 3 (East Polygon) in July 1988. 97 also followed the increase in all numbers (Fig. la.b). However, after 10 days biotransformation decreased as most of PCB congeners remained practically unchanged. Figure 2 shows Aroclor 1232 chromatograms that reflect the change in concentrations of individual PCB congeners over the experiment period. The concentration of congeners varied from 0 to 10%. Experimental data (Table 3; Figs. 3,4.5) indicate a great similarity in the rates of PCB transfomiation in various regions of the Bering and the Chukchi Seas. In the Chukchi Sea. with a thawing ice flow and a low salinity of 24.04%. the change in the MPN of bacteria under study and the rate of Aroclor 1232 transformation were similar to those found in the Bering Sea (Figs. 1,5; Table 3). Controlbottles with sterile water and PCB concentrations at 100 ng/l or 10 ng/1 remained unchanged. cells/ml 10 10 10 0 1 10 14 € PCBB I 21 days Fig. .^a. Most probable number (MPN) of saprophytic bacteria (SB, cells/ml) and PCB transforming bacteria (PCBB, cells/ml). TABLE 3 Transformation rate (degradation percentage) of individual Aroclor 1232 congeners by bacterioplankton of the Bering and the Chukchi Seas. Experiment Numbers Congeners Numbers Initial concentration of PCB 100 ng/1 1 ?• 5 10 14 21 day days days days days days Initial concentration of PCB 10 ng/1 I 3 5 10 14 21 day days days days days days ^ s 10 II 13 14 5 8 15 18 22 28 31 40 44 47 52 60 66 70 77 87 97 101 153 5 8 15 18 22 28 31 40 44 47 52 60 66 52 71 87 94 100 100 70 86 92 98 100 100 46 72 86 95 100 100 73 87 95 100 100 100 40 67 84 95 95 95 70 81 94 100 100 100 14 34 50 57 61 64 33 57 58 61 63 63 14 44 61 61 65 65 31 54 57 62 62 62 29 58 78 90 90 90 54 82 89 90 90 90 12 38 59 66 66 66 30 52 55 59 61 67 10 10 40 45 45 50 30 50 52 55 55 55 18 40 54 58 58 58 38 48 55 58 58 60 5 12 15 15 15 18 6 13 17 20 20 20 5 10 12 15 15 15 10 12 13 14 15 15 13 38 44 50 50 50 32 48 54 56 58 58 5 II 18 18 18 18 6 13 17 19 20 20 12 19 45 48 48 49 32 44 51 52 52 52 5 7 10 10 10 10 6 8 10 10 10 10 10 33 40 42 42 42 20 40 43 45 45 45 g 29 35 36 36 36 20 28 36 37 38 38 8 ")T 33 44 44 44 21 25 36 47 48 48 3 5 7 7 7 7 ■) 6 8 8 8 8 53 72 88 95 100 100 71 87 93 99 100 100 46 72 87 94 100 100 72 86 95 100 100 100 41 66 85 96 96 96 69 82 95 100 100 100 13 35 51 57 61 65 32 56 57 62 64 65 14 43 62 64 67 67 30 55 58 62 62 62 30 57 77 90 90 90 50 80 86 90 90 90 12 40 60 66 66 66 31 52 54 60 60 65 10 10 39 44 44 49 29 51 53 54 56 56 17 41 55 57 58 58 37 49 54 59 60 60 6 12 15 15 17 18 7 14 18 21 21 22 5 10 12 15 15 15 10 12 13 14 15 15 12 40 44 50 50 50 27 51 55 59 59 59 6 12 19 19 19 19 6 13 17 19 20 20 98 TABLE 3 - continued Transformation rate (degradation percentage) of individual Aroclor 1232 congeners by bactenoplantvton of the Bering and the Chul^chi Seas. Experiment Numbers Congeners Numbers day Initial concentration of PCB lOOng/l 3 5 10 14 21 days days days days days dav Initial concentration of PCB Klniz/l 5 10 14 21 days days days days day'' 8 10 I 1 i; 13 11 70 77 87 97 101 153 5 8 15 18 22 28 31 44 47 52 60 66 70 77 87 97 101 153 5 8 15 18 22 28 31 10 20 44 48 48 4S .^3 46 52 52 52 52 5 7 10 10 10 10 6 8 10 10 10 10 9 32 41 42 42 42 21 41 43 45 45 45 21 29 36 37 38 39 20 28 36 37 38 38 8 •>2 33 44 44 44 20 26 38 48 48 48 3 5 7 7 7 7 2 6 8 8 8 8 52 72 88 95 100 100 72 86 92 100 100 100 47 71 85 95 100 100 70 87 94 100 100 100 40 65 84 95 100 100 72 85 94 100 100 100 14 35 52 55 62 64 31 57 59 61 65 65 13 44 61 64 68 68 29 54 59 63 63 63 30 57 77 90 90 90 51 81 87 90 90 92 12 39 59 66 66 66 31 55 55 59 64 66 17 41 55 58 58 58 36 50 56 60 61 61 6 12 15 15 17 18 6 14 19 22 -)-) 11 4 1 1 12 14 15 15 10 12 13 14 15 15 40 41 45 51 51 51 33 50 55 57 59 62 5 12 18 18 18 18 6 13 17 19 20 20 11 19 45 48 48 49 27 47 55 56 56 56 3 7 10 10 10 10 6 8 10 10 10 10 10 32 41 42 42 43 20 42 44 46 47 48 10 28 37 38 38 38 20 23 36 37 38 38 8 22 33 44 44 44 20 25 37 47 48 50 T 5 7 7 7 7 2 6 8 8 8 8 50 72 86 94 100 100 70 88 95 98 100 100 45 72 85 96 100 100 71 87 92 100 100 100 40 65 86 95 95 95 69 87 92 100 100 100 14 35 55 55 63 65 28 55 62 64 65 65 14 44 61 66 68 68 24 56 68 64 64 64 29 59 77 89 90 90 53 81 87 90 92 92 11 39 59 66 66 66 30 52 54 58 62 66 40 10 10 39 45 45 50 22 50 53 58 58 58 44 47 52 16 41 55 58 58 58 5 12 15 15 15 18 5 11 15 15 16 16 33 55 59 62 62 63 6 18 21 ii 22 23 10 12 13 14 15 15 60 44 50 50 50 23 55 60 65 69 70 66 70 77 87 97 101 153 5 12 18 18 18 18 6 13 17 19 20 20 12 19 47 48 48 48 29 47 50 59 59 60 5 7 10 10 10 10 6 8 10 10 10 10 10 32 42 42 42 42 20 40 45 45 45 45 9 29 3H 38 38 39 20 28 36 37 38 38 8 22 33 44 44 44 20 25 42 50 50 50 3 5 7 7 7 7 2 6 8 8 8 8 99 100 Fig. 3b. Microbial transformation of individual Aroclor 1232 congeners C/c) in E.xperiment No. 2, PCB initial concentration was at 100 ng/1. Samples collected from the Gulf of Anadyr of the Bering Sea. Station 7. Numbers are coherent numbers, sec Table 2 MPN. cells/ml 10^ 10 10 PCBB a) days 0 13 5 10 14 Fig. 4a. Most probable numbers of SB and PCBB. 21 PCB' davs Fig. 4b. Microbial transformation of individual Aroclor 1232 congeners in Experiment No. 6. PCB initial concentration at 100 ng/1. water from the Chukchi Sea. Station 45. Numbers are coherent numbers, see Table 2. Lm^w Control, initial composition ot PCB Initial 8 f V 3rd dav ^Jy}^jj-M 5th day 1 7 5 11 A. A ^ Jv^ [ Fig. 5. Microbial transformation of low chlorinated Aroclor 1232 congeners (coherent numbers 5. 8. 15) at Station 4 in the southern Chukchi Sea in August 1988. Analysis of PCB congeners, after biological degradation, showed that the decomposition of the chlorinated hydrocarbon is primarily affected by stearic configurations and halogen atom substitutions. The stability of PCB congeners is probably influenced by intermolecular bonds. The decomposition of PCB occurs through the production of arene-oxides, which are substituted with biphenyl molecules in positions 2, 2', 5, 5'. Thus, the results show that only low chlorinated biphenyls are subject to rapid microbial decomposition in the arctic and subarctic waters. Many such compounds, however, are only partially transformed, which in turn may be more toxic to marine biota. Highly chlorinated biphenyls. in contrast, are extremely resistant to degradations. Consequently, these compounds may accumulate in the ecosystem and circulate in the marine environment for many decades ( Izrael & Tsyban, 1989). In summary, the results clearly show the ecological toxicity of chlorinated hydrocarbon pollution in the arctic regions. Because of low arctic temperatures, chemical degradation of xenobiotics is practically absent due to slow rates of microbial transformation. 100 Subchapter 4.4: Biologic Characteristics of Marine Microorganisms 4.4.1 Biological Features and Genotoxic Properties of Microorganisms ALLA V. TSYBAN*. GENNADIY V. PANOV, VLADIMIR A. IVANITSA*. and GALINA V. KHUDCHENKO' Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences. Moscow, USSR 'Odessa State University', Odessa, USSR Introduction Local or regional increase in the concentration of some natural components, such as heavy metals, oil, and nonnatural components up to toxic levels, is a characteristic feature of the present ecological situation in the World Ocean (Izrael et al., 1987). Therefore, a serious problem has arisen, concerning a change in the metabolism of microorganisms as well as their adaptation to new chemical conditions of the environment. It has been determined that adaptation of microorganisms plays an important role in biodegradation of toxic organic compounds. Adaptation can be defined as a change in the microbial population which increases the rate of transformation of toxic substances as a result of the preliminary contact with these compounds. It is quite obvious that to predict the biodegradation rate of organic pollutants in the marine environment, it is necessary to gain an understanding of the mechanisms of microbial transformation, such as genetic transfer or mutation, enzyme induction, and changes in the level of populations. It is also obvious that these mechanisms play an important role in the process of adaptation of microbial populations to new substances. Although mechanisms of microbial degradation may differ, the process is under the genetic control of chromosome or extra chromosomal (plasmid) material. Numerous forms of genetic transmission with plasmids can occur and can offer strong possibilities for genetic engineering in nature, including the World Ocean. Evidence in support of this can be seen in the distribution of benzo(a)pyrene- and PCB-transforming bacteria in estuaries, the Baltic, Bering, and Chukchi Seas (see preceding Subchapters). While studying the mechanisms of biodegradation. controlled by plasmids, the traits providing selective advantages to marine organisms become of primary importance. Such traits are the resistance to bactericidal toxic compounds (for instance, heavy metals) and the ability to utilize a number of substances of a biogenic origin (Karasevich, 1 982; Izrael ei al. , 1987). Thus, protective functions determined by plasmid genes can be acquired by a microbial cell under changing environmental conditions. Although other traits should not be disregarded, they are not related to direct selection. These traits provide a cell with some advantages in the habitat and possibility of transferring traits inside a bacterial population (Izrael & Tsyban, 1989). The above account outlines the importance of studying the signs of plasmid transmission in marine microorganisms. The purpose was to assess and forecast the ecological state of the environment, including protective properties of marine ecosystems. In addition, change in the genotypes of marine microorganisms can be determined (Izrael & Tsyban, 1990). New data on the biological properties of heterotrophic microorganisms of the Bering Sea were recently obtained. Investigations of the physiological, biochemical, and genetic features of strains isolated from various components of marine ecosystems were conducted by microbiologists of the Natural Environment and Climate Monitoring Laboratory (Institute for Global Climate and Ecology from 1991) of the USSR State Committee for Hydrometeorology and USSR Academy of Sciences. These materials have already been published in part by Izrael f/(;/. (1987) and Izrael &T,syban( 1989, 1990). The present paper describes research on the biological, biochemical, and genetic features of strains isolated from the Bering and Chukchi Seas in 1984 and 1988. Methods and Materials Investigations were conducted on 320 strains of heterotrophic bacteria isolated from the Bering Sea in 1984, and on 77 strains of bacteria isolated from the Chukchi Sea water in summer 1 988. Selection of traits was determined by plasmids, and methods of data processing were determined by experimental procedures. The specific character of genetic investigations of a large collection of microorganisms isolated from the marine environment has necessitated the choice of the mass screening method. The collection of the cultures was subdivided into homogeneous groups based on traits that are easily identified in mass screening (Izrael & Tsyban, 1990). Resistance of cultures to antibiotics, organic pollutants, and heavy metals (Hg, Cd, Co, Cu, Pb. and Ni) were investigated as signs of the presence of plasmids. Ability to degrade petroleum hydrocarbons and paraffin was determined from the presence of the zone where bacteria grew on the compact nutritious medium prepared on seawater (Tsyban, 1980) around sterile disks soaked with relevant hydrocarbons. Minimum inhibiting concentrations (MIC) were serially diluted in a solid medium. Eleven antibiotics of the basic groups: ampicillin (Amp), benzylpenicillin (Ben), and mcthicillin (Mtt) from the penicillin group: gentamicin ( Gen ), kanamycin ( Kan ). monomycin ( Mon ), and streptomycin (Str) from the group of aminoglycosides; chloramphenicol (Clm) and tetracycline (Tet), broad-spectrum antibiotics; polymicin (Pol) from the group of polypeptide antibiotics: and nalidixic acid (Nal) in the range of concentrations from 0.06 to 4,000 |ig/ml. Due to high sensitivity of microorganisms to gentamicin. the range of its concentration was 0.06 to 8 Hg/ml. 103 Resistance of the strains to each antibiotic taken separately, frequency of mono-, di-, and polyresistant strains, as well as resistance spectra (R-spectra) were recorded. To determine the resistance of heavy metals, the following salts were used: Hg(NO,), 2H,0, Pb(NO,),. CdCl,. CuSO, (waterless), and NiSOj in the range of 0.5 to 1,024 ng/ml. In terms of the number of ions, this amounted to 0.4-882 for Hg2=*; 0.35-670 for Pb-^ 0.3-627 for Cd-*; 0.2-464 for Co-^ and 0.15-331 forCu^ Choice of the concentrations of antibiotics and heavy metals and assessment of the bioresistance level of marine microorganisms were based on literature data. Kulskyi er al. (1986), working on the problems of natural sensitivity of different representatives of microflora from aquatic and soil biocenoses, published information on maximum permissible concentrations (MFC) of these pollutants. The genotoxic effects of cultured microorganisms were studied using a biological model including three indicator strains of Escherichia coli: E. coli WP-2 (a wild strain that retains its unchanged complete gene pool). E. coli Pol A- (a strain that is unable to synthesize one of the enzymes responsible for DNA reparation [DNA polymerase 1 ] ), and E. coli Rec- (a strain that lacks a recombination system, specified by conjugation [Slater e? a/., 1971]). Growth suppression of genetically altered strains E. coli Pol A- and E. coli Rec- to a genotoxic effect of the substrate under study was accepted as proof of its carcinogenic activity. The pathogenic properties of bacteria strains were assessed using white mice as well the cultures of human embryo kidney cells (RH) and fish skin cells (EPC) (Tsyban, 1988). Results and Discussion In the process of experimental investigations, data were obtained that characterize the following biological properties pf marine microorganisms: the relation to organic pollutants (e.g.. resistance and degradation ability), resistance to heavy metals, genotoxic and DNA-damaging properties, and pathogenicity. Growth of cultures on media containing organic pollutants is defined not only by the cultures' ability to degrade these compounds, but also by their resistance to high concentrations of pollutants. The screening test made it possible to divide the strains of the dominant taxons into three groups: /. resistant to a pollutant and capable of degradation; 2. resistant but not capableofdegradation;andi. sensitive to a pollutant (Table 1 ). The results show that microorganisms isolated from the Bering Sea are rather resistant to the impact of oil and paraffin*. The greatest activity for oil degradation was exhibited by bacteria of the genus Pseudomonas; 72.6% of active cultures occurred among them, and only 6.0% of the strains proved sensitive to oil. In the study of effects of paraffin on the tested strains, it was observed that Bering Sea microorganisms were sensitive and that 28.7% of the investigated strains failed to grow in the presence of paraffin. TABLE 1 Decomposition of petroleum hydrocarbons and paraffin by microorganisms of different taxonomic groups isolated from the Berina Sea. Genus Number Percent of positively tested strains of strains Oil Paraffin DR R S DR R S Pseiidoinonas 84 72.6 21.4 6.0 65.5 10.7 23.8 Bacterium 52 69.2 25.0 5.8 67.3 17.3 15.4 Pkmococcus 58 65.5 27.6 6.9 62.1 5.2 32.7 Bacillus 76 69.7 23.7 6.6 53.9 7.9 38.2 Other genera 47 66.0 23.4 10.6 46.8 21.3 31.9 TOTAL 317 69.1 24.0 6.9 59.6 11.7 28.7 Note: D = decomposition; R = resistance; S = sensitivity. One of the processes occurring in natural microbial populations is microevolution of bacteria, proceeding under the selective pressure of anthropogenic factors. Thus, a variety of microorganisms may develop in their bioresistance to a number of pollutants. The mechanism of acquired poly resistance to unfavorable environmental factors is based on the intensive intra- and interspecific exchange of extrachromosomic elements of nuclear material (i.e.. plasmids). The level of this exchange is highest in sewage and may be the same in water bodies having high pollution levels (Baya er al., 1986; Kulskyi ef al.. 1986; Day et al.. 1987; Boominathan el al.. 1988; Gealt, 1988; Lmton, 1988; Schmidt & Schlegel, 1989). The character and level of antibiotic resistance were studied in representatives of the genera Pseudomo)uis and Bacillus that dominate in the microbial communities of the Bering and Chukchi Seas. MIC of antibiotics, the proportion of sensitive and stable strains, the number of resistance determinants, and the most widespread R-spectra were determined. In the study of R-strain distribution, the strains for which the MIC of an antibiotic exceeded 31.2 |ag/ml (2 |ig/ml for gentamicin), were considered R-strains. A common feature of all represented taxonomic groups of Bering Sea microorganisms was the small percentage of strains sensitive to all the antibiotics (0 to 6.3% in different taxonomic groups). The percentage of strains resistant to one antibiotic averaged 24.6%, with a maximum value for the representatives of Bacillus genus (37.5%). Strains resistant to two antibiotics occurred on average 12.0%, with small variations among different taxonomic groups, a range of 8.3-15.6%. Strains resistant to methicillin were most frequent and dominated among the representatives of the genera Pseudomonas and Planococcus (54.2 and 46.5%, respectively). They averaged 43.5% (Table 2). 104 TABLE 2 Resistance of Bering Sea microorganisms of different taxonomic groups to antibiotics (the proportion of resistant strains - R-strains, %). Total Genus of number of the strains Antibiot cs micro- Penicillins .■\minoglvcoside s organisms Amp Ben Krh Mtt 0\c Gen Kail Mon Ris Str Pseudomonas 48 45.8 37.5 20.8 54.2 56.3 16.7 14.6 16.7 37.5 12.5 Planococcus 43 27.9 23.3 9.3 46.5 39.5 2.3 32.6 27.9 20.9 23.3 Bacillus 64 21.9 18.8 9.4 32.8 25.0 6.3 4.7 1.6 10.9 7.8 Other genera 36 38.9 3 1 .0 8.3 44.4 52.8 11.1 8.3 13.9 TT ~l 16.7 TOTAL 191 32.3 26.7 12.0 43.5 41.4 8.9 14.1 13.6 22.0 14.1 Multiple resistance to antibiotics was typical of the majoiity of the heterotrophic microorganisms, isolated in the Bering Sea basin, irrespective of their taxonomic position. The percentage of such strains was 60.8%. The highest percentage found in the genera Pseudomonas and Planococcus was 70.8 and 67.5%. respectively (Table 3). TABLE 3 Number of determinants of resistance to antibiotics with microorganisms of different taxonomic groups. Total Percent number Genus of the Sensi- Monore- Diresis- Polyre- strains tive sistant tant sistant PseiuUnmmas 48 2.1 14.6 12.5 70.8 Planococcus 43 2.3 18.6 11.6 67.5 Bacillus 64 6.3 37.5 15.6 40.6 Other 10 genera 36 0 27.8 8.3 63.9 TOTAL 191 2.6 24.6 12.0 60.8 The percentage of microorganisms resistant to natural and semisynthetic penicillins ranged from 12.0% for carbenicillin to 26.7-41.4% forbenzylpenicillin, ampicillin, and oxacillin. The tendency was typical of all taxonomic groups. However, most strains were among the genus Pseudonumas (above 50% in some cases). Resistance to antibiotics is characteristic of Pseudomonades (Palleroni, 1975). Resistance of Bering Sea heterotrophic microorganisms to aminoglycosides occurred much less frequently. Maximum resistance to hentamycin, kanamycin. monomycin, and streptomycin varied from 8.9 to 1 4. 17f. Resistance to ristomycin was somewhat higher (22.2%). Among the different taxonomic groups, the greatest number of strains resistant to aminoglycosides occurred in the genus Planococcus. Analysis of resistance spectra of Bering Sea strains of the main taxonomic groups revealed great diversity (42. 37, and 33 spectra in the genera Pseudomonas. Planococcus. and Bacillus. respectively) as well as the absence of the dominating R-spectra. Diversity of R-spectra can probably be considered as an indication of an extraordinary genetic plasticity of the studied Bering Sea microorganisms. The study of antibiotic resistance of the strains isolated from Chukchi Sea water was conducted and compared with antibiotic resistance of the strains isolated from the Baltic Sea — an impact region of the World Ocean (Table 4). TABLE 4 Resistance of the microorganisms of the Chukchi and Baltic Seas (the proportion of R-strains, %). Genera of microorganisms Antibiotics Pseudom Chukchi Sea modes Baltic Sea Others Chukchi Sea B altic Sea Amp 14.8 77.8 8.8 68.2 Ben 70.3 93.3 64.7 90.9 Mtt 100.0 86.7 79.4 95.5 Gen 11.1 6.7 14.7 13.6 Kan im 17.8 58.8 50.0 Mon 92.6 28.9 67.6 68.2 Str 33.3 35.6 23.5 36.4 Clni 33.3 86.7 17.6 86.4 Nal 63.0 95.6 61.8 95.5 In Table 2, Pseudomonades of the Chukchi Sea were characterized by resistance to benzylpenicillin and methicillin, kanamycin and monomycin (77.7 and 92.6%, respectively), and nevigramon-nalidixic acid (63.0%). The majority of the Chukchi Sea strains showed a low resistance to gentamicin (11.1%) like those of the Baltic Sea. Only one-third of the strains proved resistant to streptomycin (33.3 %). Pseudomonades from the Chukchi and Baltic Seas were distinguished by the number of strains resistant to ampicillin, levomycetin, kanamycin, and monomycin. The proportion of the strains from the Chukchi Sea, which were resistant to the first two antibiotics, were considerably less than of Baltic Pseudomonades (14.8 and 33.3% versus 77.8 and 86.7%, respectively). As far as resistance to kanamycin is concerned. 105 the contrary situation was observed. The percentage of the strains resistant to kanamycin and other aminoglycosides in the Chukchi Sea were considerably higher (77.7 and 92.6% versus 17.9 and 28.9% in the Baltic Sea). The similar irregularities were found for other genera, isolated from the Chukchi Sea (Table 4). It should be noted that the modal values of MIC of antibiotics for Pseitdomanades from the Chukchi Sea did not exceed (except for methicillin) 1 25 |ig/ml. while in similar repre.sentatives of Baltic microflora, the modal MIC values of all antibiotics of the groups of penicillins, chloramphenicol, polymyxin, and nevigramon were 1,000 |ag/ml (Table 5). TABLE 5 Modal values of the MIC of antibiotics for murine bacteria, percent. TABLE 6 Antibioticogram of strains of marine Pseudomonades from the Chukchi Sea. Genera of microorganisms Antibiotics Pseudomonades Others Chukchi Sea Baltic Sea Chukchi Sea Baltic Sea Amp 7.8/40.7 > 1.000.0/60.0 7.8/32.4 > 1.000.0/36.4 Ben 31-125.0/18.5 > 1,000.0/73.3 250.0/26.5 > 1,000.0/77.3 Mtt > 1,000.0/62.9 > 1,000.0/84.4 > 1,000.0/50.0 > 1,000.0/90.9 Gen 0.5/55.6 0.3/31.1 0.5/38.2 1.0/36.4 Kail 62.5/37.0 15.6/31.1 31.2/20.6 125.0/27.3 Mon 125.0/40.7 15.6/37.7 250.0/23.5 62.5/27.3 Str 31.2/33.3 7.8/31.1 15.6/38.2 > 1,000.0/27. 3 Clm 15.6/29.6 >l,000.(J/46.6 7.8/47.1 > 1,000.0/3 1.8 Nal 250.0/25.9 > 1,000.0/40.0 15.6/23.5 > 1,000.0/68.2 Note: Modal values of the MIC (jjg/ml) are in the numerator; the proportion of strains with the given modal values (%) in the denominator. A similar situation was revealed in the analysis of the modal MIC values for other heterotrophic microorganisms of the. Chukchi Sea. Among the Pseudomonades of both the Chukchi and Baltic Seas, the percentage of those that are shown to be polyresistant to antibiotics is high (92.5%). Combination of resistance determinants are presented by 18 R-spectra. In contrast to Baltic strains, no dominating R-speclrum was revealed in Chukchi strains (Table 6). To determine if it is appropriate to relate the diversity of R-spectra and polyresistance to the antibiotics of the dominating taxonomic groups of heterotrophic microorganisms as criteria of the pollution level of the region under investigation, a comparison of data was obtained for Pseudomonas bacteria, isolated from the Bering, Chukchi, and Baltic Seas (Fig. 1, Table 4). In Fig. I, antibiotics were grouped according to the resistance to them by marine microorganisms. Resistance to the first group, comprising ampicillin, kanamycin, and streptomycin, is determined by plasmid genes. Resistance to the second group, comprising benzylpenicillin, methicillin, and monomycin, is determined by chromosomic genes. Figure 1 shows that in the Baltic and Chukchi Seas, among bacteria in the genus Pseiidoimmas. the number of strains resistant to the antibiotics is much higher than that in the Bering Sea. In the Baltic Sea, microorganisms of other taxonomic groups were Distribution among the spectra Abs. R-spectra number percent Amp Ben Mtt Kan Mon Str Clm Nal 2 7.4 Amp Ben Mtt Mon Str Clm Nal 1 3.7 Ben Mtt Kan Mon Str Clm Nal 2 7.4 Ben Mtt Ger 1 Kan Mon Str Clm 1 3.7 Ben Mtt Kan Mon Clm Nal 1 3.7 Ben Mtt Ger 1 Kan Mon Str 1 3.7 Amp Ben Mtt Kan Nal 1 3.7 Ben Mtt Kan Mon Nal 3 11. 1 Mtt Kan Mon Str Nal 1 3.7 Mtt Ger 1 Kan Mon Str 1 3.7 Ben Mtt Kan Mon 4 14.8 Ben Mtt Mon Nal ~> 7.4 Ben Mtt Kan Nal 1 3.7 Mtt Kan Mon Nal -> 7.4 Mtt Mon Clm 1 3.7 Mtt Mon Nal 1 3.7 Mtt Mon 1 3.7 Mtt 1 3.7 more resistant to antibiotics than those in the Chukchi Sea. In the Bering Sea, they were the most sensitive to antibiotics. Of special interest, in the Chukchi Sea, the Pseudomonades and other microorganisms showed more resistance to those antibiotics, which was determined by chromosomic genes. Bacteria of the genus Pseudomonas from the impact region of the Baltic Sea possessed a rather high sensitivity to aminoglycosides, especially to gentamicin and kanamycin. Resistance to penicillins was also found in 77.8-93.3% of the cases. In this case, the number of polyresistant strains, having three and more determinants of polyresistance, accounted for 95.6%. However, the Baltic strains also possessed the dominating R-spectrum in 42.2% of the strains. This information suggests that among the dominant heterotrophic microtlora in the Chukchi and Bering Seas, the formation of strains resistant to antibiotics exists. However, their abundance as a whole is less than in the impact region of the World Ocean, such as the Baltic Sea. Thus, it is possible to state that the percentage of resistance spectra and the level of polyresistant strains in bacterial cenoses reflect the level of pollution in the region. Based on toxicological estimates of "stress indices," heavy metals ranks second among pollutants behind pesticides ( Izrael & Tsyban, 1989). Therefore, the abundance of dominant marine bacteria that are resistant to heavy metals, may also characterize the degree of marine pollution. To examine this hypothesis the resistance of Chukchi Sea microflora to Cd, Co, Cu, Ni, Hg, and Ph ions was investigated. Similar responses of the strains from the Baltic Sea were studied for comparison (Tables 7,8). 106 R. % - proponion of resistant strains of microorganisi 100 - AmpicitlfitAmp) Genlamvcin fGeni Kunttmycin iKanf Slrepu>m\cin fSlr) AmpitillintAmp) Genfamycin (Gent Karuinyctn (Kant Slrepiomycin iSlr) BenzilpeniiHlintBfn) MeuaUin tMii) Monomycin iMon) Fig. I . Resistance of marine microorganisms to antibiotics. Thirty-three strains of Pseiidomonades, 1 7 strains of other bacillary bacteria (including 7 strains from the group Flavobacterium-Cytophaga. 5 from the ^Qnu^Arthrohacter, 2 from the genus Bacillus), and 12 strains of coccal forms (including 8 strains from the genus Siaphylococcus, 2 from the genus PUmococcus, and 2 from the genus Micrococcus) were studied for resistance to heavy metals. Results show that strains from the Chukchi Sea respond to heavy metals as those from the Baltic Sea; that is. a wide MIC range and high modal MIC values were found. These results suggest that bacteria from the Chukchi Sea have adapted to high concentrations of heavy metals. Because all groups of bacteria did not differ in the mode and MIC range of cadmium and lead, natural stability of the strains is one explanation. However, modal values for Co, Cu, Hg. and. partially. Ni. are substantially lower in Chukchi Sea strains relative to those from the Baltic Sea. For instance, the mode of cobalt MIC was 1.024 mg/1 for Chukchi Sea strains and 128 mg/1 for Baltic strains, while that for Cu was 256 and 128 mg/l and Hg was 32 and 16 mg/1. respectively. However, for Chukchi Sea strains, the lower and upper values of the MIC range were somewhat lower for most metals. Although specific strains from the Chukchi Sea are resistant to heavy metals, their resistance was considerably lower than in strains from the Baltic Sea. Anthropogenic pollution of marine waters with chemical substances produces a considerable negative effect on the genetic apparatus of microbes. This effect is due to mutagenic and genotoxic material of certain pollutants. Microorganisms are not only targets for the genotoxicants or mutagenes, but in some cases they themselves enhance the effect and strengthen it. Thus, microorganisms can, in the process of decomposition, activate transforming pollutants into more toxic forms. Similarly, it is acknowledged that microorganisms produce different biologically active substances that elicit a broad antibiotic effect. The chemical composition and structure of these compounds suggest that they can also possess mutagenic and genotoxic effects and, under environmental pressures, the mutagenic and genotoxic activity of microorganisms themselves can be strengthened. Thus, the development of marine microorganisms, conditioned by chemical pollution, can serve as an extra factor that strengthens the mutagenic stress upon microbial communities. If ecological conditions continue to deteriorate as in some regions of the World Ocean, the frequency of induced mutations may increase, resulting in an artificial evolution of bacterial strains. The problem of mutagenic, genotoxic, and carcinogenic effect of marine pollution, and the role of the microorganisms are not yet investigated. To detect genotoxic and DNA-damaging effects of chemical compounds, bacteria that are most sensitive are widely used. The disturbance of bacteria genotype is immediately expressed in its phenotype because of the gaploid chromosomes. In addition, a high level of correlation is observed between mutagenic activity found in microorganisms and their carcinogenic properties in animals. Therefore, three strains of Escherichia coli were used for the genetic screening: E. coli WP-2, E. coli Rec-, and E. coli Pol A-. Sixty-two strains of bacteria capable of decomposing hydrocarbons and cyclic organic compounds of the Bering Sea were studied. This work involved: I. heat-killed marine bacteria; 2. exometabolites — metabolic products released by bacteria into the culture medium; and J. endometabolites — metabolites contained in bacterial cells and released by ultrasound disintegration. The investigations showed that the ability to synthesize metabolites with general toxic activity and DNA-damaging effect was common to the different taxonomic groups of Pseudomonas. Bacterium. Alcaligenes. Planococcus. Flavobacterium-Cytophaga. Xantomonas, Arthrobacter. and Bacillus. The general toxic effect of Pseudomonades was noted for exo- and endometabolites and killed cells at 75, 50, and eO'/f of the 32 strains, respectively (Table 9). The DNA- damaging effect was found in 83% of all Bering Sea strains. The results suggest that the genotoxic effect of the genus Pseudomonas is not a specific feature of this genus. On E. coli Pol A- model this effect was typical of exometabolites found in 69% of the strains, endometabolites in 54% of the strains, heat- 107 TABLE 7 Range of heavy metal MIC values for microorganisms of the Chukchi and Baltic Seas Range of heavy metal MIC values, mg/1 Other non- Metallions Seas Pseudoincmades spore forming rods Bacilli Micrococci Cd-' Chukchi 136.7 19.6-313.4 19.6-156.7 39.2-156.7 ' Baltic 78.3-313.4 78.3-313.4 39.2-156.7 not investigated Co-* Chukchi 14.5-116.2 29.0-116.2 29.0-116.2 29.0-116.2 Baltic 29.0-464.7 232.3-464.7 29.2-4 not investigated Cu-* Chukchi 10.0-39.9 10.0-39.9 2.5-39.9 10.0-39.9 Baltic 20.0-39.9 20.0-39.9 20.0-39.9 not investigated Ni-* Chukchi 96.5-386.0 96.5-386.0 96.5-386.0 96.5-386.0 Baltic 48.0-386.0 96.5-386.0 96.5-386.0 not investigated Hg^* ChukThi 2.4-19.3 4.8-19.3 4.8-19.3 4.8-19.3 Baltic 4.8-38.5 4,8-38.5 4.8-19.3 not investigated Pb=* Chukchi 160.1-640.4 80.0-320.2 40.0-320.2 160.1-320.2 Baltic 80.0-320.2 160.1-320.2 160.1-640.1 not investigated TABLE 8 Modal MIC values of heavy metal salts for marine bacteria from the Chukchi and Baltic Seas. Mode of MIC of strains ( n- ig/l)/percent Other non- Metallions Seas Pseiidomonades spore fomiing rods Bacilli Micrococci CdCl, Chukchi 256/90.9 256/76.4 256/50.0 256/58.3 Baltic 256/40.6 128-256/35.7 256/42.9 not investigated CoCl, Chukchi 128/48.5 128/58.8 128/58.4 128/58.4 Baltic 1,024/59.5 512-1,024/42.9 1,024/42.9 not investigated CUSO4 Chukchi 128/45.4 128/58.8 64/41.7 128/58.4 Baltic 256/67.6 256/71.4 256/64.3 not investigated NiS04 Chukchi 1.024/42.4 256-512/35.3 256/50.0 512/50.0 Baltic 1,024/62.2 512-1,024/35.7 512/50.0 not investigated Hg(N0,),2H,0 Chukchi 16/51.5 16/58.8 16/41.716/50.0 Baltic 32/35.1 32/35.7 32/42.9 not investigated Pb(NO,)2 Chukchi 256/51.5 256/82.3 256/66.7 256/75.0 Baltic 256/8 1 . 1 256/85.8 256/85.8 not investigated Note: Modal values (mode) of MIC is in the numerator; propoilion of the strains resistant to the given concentration of the metal ions is in the denominator. 108 killed cells in 38% of the strains. On the E. coli Rec- niodel. the above figures were 50, 50. and 67'7f , respectively ( Table 9 ). Twenty-eight percent of the strains of Bering Sea Pseudomonades produce compounds possessing DNA- damaging effect upon both mutant strains. This suggests carcinogenic activity. TABLE 9 Toxic and DNA-damaging effects of metabolites of Psfuddimmadi's from the Bering Sea. Number of strains (%) with positive effect Test-object Exometa- Endometa- Killed bolites bolites cells E. coli WP-2 E. coli Pol A- E. coli Rec- 75 50 60 69 54 38 50 50 67 In representatives of the F/(n'()/«(rr('/7H/;;-Cv/( '/'/;«,!,'(/ group, DNA-damaging effect appears considerably lower than the Pseudomonas. Only one of the seven strains gave a positive effect in the model E. coli Pol A-. From the comparison of the results on toxic and genotoxic properties of the metabolites of the genus Pseudomonas isolated from the Bering and Chukchi Seas, it was found that the Chukchi Sea occupies an intermediate position between the Baltic and Bering Seas. With respect to an increase in the number of strains possessing the genotoxic activity, the seas are listed in the order of the Bering Sea, the Chukchi Sea, and the Baltic Sea. Thus, investigations showed that an ability to produce metabolites with a genotoxic effect is a marginal characteristic of marine bacteria, such as Pseudomonas, Alcaligenes, Xaiitomoiias. Arthrohaclcr, Bacillus, and Flavnhactehum- Cytopliaga. However, the ability of marine bacteria to produce substances possessing genotoxic activity, which was determined under laboratory conditions, does not affirm if these properties are dangerous under natural conditions. It remains unknown whether bacteria produce a genotoxic effect in the marine environment. To determine the minimum concentrations of bacteria, sufficient to elicit DNA-damaging effect, three strains of the Elavi)hacterium-Cytf>pha,i>a group, which manifested a genotoxic effect, were used. It was detennined that the maximum dilution of exometabolites, at which the DNA-damaging action was preserved, was 1:125. This corresponds to a bacterial density in seawater on the order of 1 x 10' cells/ml under experimental conditions. The active dilution for two other strains ranged from 1 :25 to 1 :5. This corresponds to a bacterial density to 1 x 10' to 1 x 10'' cells/ml. Exo- and endometabolites of four strains (including the above strains) with genotoxic and DNA-damaging effects were analyzed by means of the standard Ames test. The purpose is to elucidate questions about mutagenic activity. As test strains, the specialized strains Salmonella typhimurium TA-98 and TA- 100. when used, revert to prototrophicity with respect to histidine due to mutation of a reading frame shift and replacement of base pairs. The results from this test suggest that one of the four strains produced metabolites with mutagenic activity. Exometabolites of this strain, in a volume of 0. 1 ml per Petri cap, induced genetic mutations of the frame shift type. The frequency of occurrence was more than 40 times higher than spontaneous mutation (82.6 x 10*% as compared to the control value of 2.0 X 10"%). Of great importance seems to be the DNA-damaging effect clearly marked in the genus Pseudomonas. This genus has gained an advantage in conditions of marine pollution and develop in waters subjected to heavy anthropogenic inputs. So we speculate that the development of indicator microfiora, which includes bacterial decomposers in impact regions of the World Ocean, is secondary pollution of the marine environment (i.e., intensifying the potential response of chemical pollution and threatening the genotype of marine ecosystems). The ability of certain forms of microorganisms to change under the effect of chemical pollution can be far from safe for other marine organisms and man. There is a risk of possible genetic transformation of harmless bacteria under the pressure of the environmental mutagens and selection towards aggressive pathogenic forms of microorganisms. The risk increases if the protective mechanisms of animals and man have not yet adapted. In this case, transformation of the microorganisms can mutate from the nonpathogenic to quasi-pathogenic group and from the latter into the pathogenic group. Two main models are used to determine pathogenicity of microorganisms. One is classical and is based on the reproduction of an infection process in laboratory animals. The other examines the effect of bacteria on man and animal cell cultures as a model. Cell cultures provide a less expensive, rapid answer, with a more stable assay with higher sensitivity and reliability than results with experimental animals. Pathogenic properties of 1 4 strains from the Bering Sea, 1 8 strains from the Chukchi Sea, and 27 strains from the Baltic Sea were studied with the use of white mice and the reinoculated kidney cells of a human embryo (RH) and fish skin cells (EPC) (Tsybanf/«/.. 1988). The study included 26 strains of two groups of bacterial populations. These groups were Pseudomonas and Flavobacterium-Cytophaga, isolated from the Bering Sea and other regions of the World Ocean. With the use of the model of intraperitoneal infection, white mice did not reveal pathogenic properties. However, the use of cell cultures revealed a differentiation of strains by the level of potential pathogenic activity of bacteria cells. The cytopathic effects cause morphological changes of cells and disruption of the monolayer. For pathogenic strains, cytopathic response occurred in 50-100% of the tests, quasi- pathogenic (potentially pathogenic) strains — 25-50%, and nonpathogenic strains — less than 25%. Changes observed included vacuolization of cytoplasm, rounding-off of some cells, and acidification of the medium. For controls, two species were used: Pseudomonas fluorescence BKM-894(H) 109 as nonpathogenic, and Pseudomonas aeruginosa 2-9 as pathogenic. Cytopathic effect of these strains on RH ceils suggested that P. fluorescence BKM-894(H) did not produce an appreciable effect on the cell culture, while the aggressive strain P. aeruginosa 2-9 killed laboratory animals, destroyed the cell culture monolayer by 75-100% after 48 hours and completely suppressed the mitotic activity of the cells. Analysis of cytopathic data (Table 10) showed that 44.5, 44.4, and 11.1% of the bacterial strains of the genus Pseudomonas, isolated from the Baltic Sea, were pathogenic, quasi-pathogenic (potentially pathogenic), and nonpathogenic strains, respectively. Thus, both the quantitative and qualitative assessment of cytopathic data suggests a high pathogenicity of Baltic strains, and much higher than those of Bering strains. These results support the related level of anthropogenic pollution in the Baltic Sea (an impact region) and the Bering Sea (a background region). In the Chukchi Sea, the proportions of pathogenic, quasi-pathogenic, and nonpathogenic strains made up 66.7, 1 1 .2. and 22.2% of the total number of the investigated strains, respectively. TABLE 10 Cytopathic effect of the strains of Pseudoinonades on the culture of RH cells from the Bering, Chukchi and Baltic Seas. The proportion of strains with cytopathic effecl, % Region Nonpathogenic Potentially pathogenic Pathogenic BerinaSea 1984 Chukchi Sea 1988 Baltic Sea 1987 42.9 11.1 50.0 1.1 44.4 7.1 66.7 44.5 The discovery of pathogenic microorganisms in the Chukchi Sea is of much interest and requires a thorough study. The limited information available restricts an interpretation about the cause of this phenomenon. The results of parallel investigations of the cytopathic effect and invasive properties of 1 8 strains oi Pseudomonas and Flavobacterium-Cytophaga using the culture of kidney cells of a human embryo ( RH ) and fish skin cells (EPC) are shown in Table 1 1. The study of Baltic and Chukchi Seas strains, using the model of fish skin cells (EPC) made it possible to determine their pathogenic properties against fish. The comparison showed that 64. 2% of the studied strains possessed cytopathic action. The results also showed that a number of strains that did not manifest pathogenic properties on human cells produced cytopathic effects on fish cells. This confirms the different degree of pathogenicity of the same strains of marine bacteria for man and fish. TABLE 11 Cytopathic effect of the strains of Pseudomonades from the Chukchi and Baltic Seas on the culture of RH and EPC cells. Proportion of strains, % Number of the Pathogenic Potentially Nonpathogenic Region investigated pathogenic slrains RH EPC RH EPC RH EPC Chukchi Sea, 1988 18 66.7 77.8 22 2 22.2 0 Baltic Sea, 1987 14 50.0 71.4 50.0 28.6 0 0 Thus, these investigations suggest that under the pressure ofchemical pollutants, pathogenic properties of microorganisms can change as a result of transfomiation and selection. Besides an ability to decompose complex organic compounds and resist the action of antibiotics, heavy metals, and xenobiotics. marine microflora can acquire pathogenic properties. The discovered tendencies for increasing the aggressiveness of marine bacteria are based on the adaptation of the bacterial community to new chemical substrates, conditioned by transfer of genetic determinants. The process is accompanied by the selection and accumulation of strains in the polluted environment. These strains contain plasmids for decomposition of and resistance to xenobiotics. Based on the premise (Rochelle etal. 1 989 iofconjugation in one plasmid of genes responsible for decomposition and resistance to xenobiotics, with genes of antibiotics resistance and pathogenic properties, we hypothesize that the processes of adaptation of microorganisms to chemical pollution are accompanied by selection and accumulation of strains pathogenic for fish and man. This transition of microorganisms from saprophytes to quasi-pathogenic (potentially pathogenic ) and eventually pathogenic poses serious concerns for marine mammals and man. 110 Chapter 4 References Ahmed, M. & Focht. D. D. (1973). Degradation of polychlorinaled biphenyls by two species of Achromobacter. Can. J. MIcrohlnl. 19, 47-52. Atlas, R.M.( 1984). Microbiological degradation of petroleum hydrocarbons: An environmental perspective. MIcrohiol. Rev. 45. 180-209. Atlas, R. M.. Schofield. E. A., Morelli, F. A. and Cameron. R. E. (1976). Effects of petroleum pollutants on arctic microbial populations. Environ. PoUia. 10( 1 ), 35—43. Azam, F., Ammerman, J. W. & Cooper. N. (1981). Bacterioplankton distributional patterns and metabolic activities in the Scotia Sea. Antarctic J. U.S. 16, 164-165. Babenzien, H. B. & Schwartz, W. (1970). Studies of the microbiology of neuston. Limnologica 7, 247-171. (in Russian) Baitaz, O. N. & Baitaz, V. A. (1986). Some data about spatial distribution of bacterioplankton in the Bering Sea. Complex oceanological studies of the Barents and White Seas. Apatites, pp. 84-89. (in Russian) Ballschmitter,K.&Zell,M.(1980). Analysisofpolychlorinated biphenyls (PCB) by glass capillary gas chromatography. Freseniiis Z. Anal. Chem. 302, 20-3 1 . Baya, A. M., Brayton, P. R., Broun, V. L., Grimes, D. J., Russek-Cohen, E. & Colwell, R. R. (1986). Coincident plasmids and antimicrobial resistance in marine bacteria isolated from polluted and nonpolluted Atlantic Ocean samples. Appl. Environ. Microbiol. 51(6), 1285-1292. Bedard, D. L., Haberl, M. L., May, R. & Brennan, M. J. (1987a). Evidence for novel mechanisms of polychlorinated biphenyl metabolism in Alcalii>ene.\ ciitropus H850. Appl. Environ. Microbiol. 53, 1 103-1 112. Bedard, D. L., Untemian, R., Bopp, L. H., Brennan, M. J., Haberl M. L. & Johnson, C. (1986). Rapid assay for screening and characterizing microorganisms for the ability to degrade polychlorinated biphenyls. Appl. Environ. Microbiol. 51,61-768. Bedard, D. L., Wagner, R. E., Brennan. J. J., Haber, M. L. & Brown, J. F. ( 1987b). Extensive degradation of Aroclor and environmentally transfomied polychlorinated biphenyls by Alcaligenes eutrophus H850. Appl. Environ. Microbiol. 53, 1094-1102. Bemhard. M. & George. S. G. ( 1986). Importance of chemical species in uptake loss and toxicity of elements for marine organisms. Importance Chem. Speciat. Environ. Proce.s.s. Kept. Dahlem. Workshop. Berlin. 2-7 September. 1987. pp. 385-422. Bemhard. M. & Zattera. A. (1975). Major pollutants in marine en\ironment. In Marine Pollution and Marine Waste Disposal. Pergamon Press, Oxford and New York, pp. 195-300. Bidleman, T. F. & Olney, C. E. (1974). Chlorinated hydrocarbons in the Sargasso Sea atmosphere and surface water. 5r;>/(r£' 183, 516-518. Bidleman, T. F., Olney, C. E. & Rice, C. P. (1976). High molecular weight chlorinated hydrocarbons in the air and sea; rates and mechanisms ofair sea transfer. In Mar.Pollut. Transfer 10, 346. Birger. M. O. (ed. ) ( 1 973 ). Reference Book forMicrobioloi-ical and Virusological Methods of Investigation. Medicina Publishers, Mo.scow. pp. 177-180. (in Russian) Bletchly.J.D. (1984). Polychlorinated biphenyls: Production, current use, and possible rates of future disposal of OECD member countries. In Proceedings of PCB Seminar (M. C. Barvos, ed. ). pp. 343-372. Ministry of Housing, Physical Planning and Environment, The Netherlands. Boominathan, K., Gurujeyakshmi, G„ Balajee, S. & Mahadevan (1988). Xeno-disimilatory plasmids. Curr. Sci. (India) 57(21). 1182. Bopp, L. N. (1986). Degradation of highly chlorinated PCB"s by Pseiidomonas sp. strain LB400. J. hid. Microbiol. 1, 23-29. Braginsky, L. P. (1986). Certain regularities and reaction mechanism of freshwater ecosystems to pesticides and surfactants. E.\p. Aqiiat.To.xicol. 11, 7-22. (in Russian) Brunner. W., Suthedad, F. N. & Focht. D. D. (1985). Enhanced biodegradation of polychlorinated biphenyls in soil by analog enrichment and bacterial inoculation. J. Environ. Qiial. 14, 324-328. Buchanan & Gibbons (eds. ) (1982). Bergey's Manual of Determinative Bacteriology (8th ed.), pp. 196-207. The Williams and Wilkins Co., Baltimore, Maryland. Bullion. V. V. (1988). Extracellular production of phytoplankton and research methodology. J. Hydrobiol. 24, 64-73. (in Russian) Bumpus. J. (1989). Biodegradation of polycyclic aromatic hydrocarbons by Phaiierochaete chnsosporiiim. Applied Environ. Sci.. pp. 154-158. Cadee, G. C. ( 1988). Organic carbon in the upper 100 m and downward tlux in the Banda sea; monsoonal difference. Neth. J. Sea Res. 22, 109-121. Chemyak. S. M. & Mikhaleva. J. M. (1985). Chlorinated hydrocarbons in the Baltic Sea biota. In Study of the Baltic Sea Eco.system. 2. 82-84. Gidrometeoizdat Publishers. Leningrad, (in Russian) Dahlback, B., Gunnarson, L. A. H., Hermansson, M. & Kielleberg, S. (1982). Microbial investigation of suri'ace microlayers, waters column, ice and sediment in the Arctic Ocean. Mar. Ecol. Progr. Ser. 9. 101-109. Day, M. J., Bale. M. J. & Fry. J. C. (1988). Plasmid transfer in the freshwater environment. Safety Assur. Environ. Intro. Genet. Eng. Organ. : Proc. NATO Adv. Res. Workshop, Rome. 6-10 June, 1987. Beriin, pp. 181-197. Dean-Ross, D. (1987). Biodegradation of toxic waste in soil. A^A/A-fH-.v 53, 490-492. ill Dobrovolski, A. D. & Zalogin. B. S. (1982). The seas of the USSR. M. P. H. of Moscow State University, (in Russian) Douglas, D. J., Novitsky, J. A., & Foumier, R. O. (1987). Microautoradiography-based enumeration of bacteria with estimates of thy midine-specific growth and production rates. Mar. Ecol. Prog. Sen 36, 91-99. Ducklow. H. W. & Hill, S. M. (1985). Tritiated thymidine incorporation and the growth heterotrophic bacteria in warm core rings. Limnol. Oceanogr. 30. 260-272. Erickson, M. D. (1986). Analytical chemistry of PCB's. Butterworth Publishers, Boston. Massachusetts, pp. 5-53. Fedoseyeva, G. E. & Khessina, A. la. ( 1968). Application of quasilinear spectra of luminescence for quantitative detemiination of polycyclic hydrocarbons series. J. Appl. Spectr. 9(2), 282-288. Fogg, G. E. ( 1 97 1 ). Extracellularproducts of algae in freshwater. Arch. Hydrobiol. Beeh. 5, 1-25. Fuhrman, J. A. (1981). Influence of method on the apparent size distribution of bacterioplankton cells: epifluorescence microscopy compared to scanning electron microscopy. Mar. Ecol. Prog. Sen 5, 103-106. Fuhrman, J. A., Ammerman, J. W. & Azam, F. (1980). Bacterioplankton in the coastal eutrophic zone: distribution, activity and possible relationships with phytoplankton. Mar. Biol. 60, 201-207. Fuhrman, J. A. & Azam, F. (1980). Bacterioplankton secondary production estimates for coastal waters of British Columbia, Antarctica, and California. Appl. Environ. Microbiol. 39, 1085-1095. Fuhrman, J. A. & Azam, F. ( 1982). Thymidine incorporation as a measure of heterotrophic bacterioplankton production in marine surface waters: Evaluation and field results. Mar. Biol. 66, 109-120. Furukawa, K. (1982). Microbial degradation of polychlorinated biphenyls (PCB's). In Biodegradation and Deto.xication of •Environmental Pollutants (A. M. Chakrabarty, ed.), pp. 33-57. CRC Press, Boca Raton, Florida. Furukawa, K. & Chakrabarty, A. M. ( 1982). Involvement of plasmids in total degradation of polychlorinated biphenyls. Appl. Environ. Microbiol. 44, 619-626. Furukawa, K., Matsumura, F. & Tonomura, K. (1978). Alcaligenes and Acinetobacter strains capable of degrading polychlorinated biphenyls. Agric. Biol. C/)e;?!. 42,543-548. Furukawa, K.. Tomizuka, N. & Kamibayashi, A. (1979). Effect of chlorine substitution on bacterial metabolism of various polychlorinated biphenyls. Appl. Environ. Microbiol. 38,308-310. Furukawa, K., Tomizuka, N. & Kamibayashi, A. (1083). Metabolic breakdown of Kaneclors (polychlorophenyls) and their products by Acinetobacter sp. Environ. Microbiol. 46, 140-145. Garrison, D. L., Sullivan, C. W., & Ackley, S. F. (1986). Sea ice microbial communities in Antarctica. Bioscience 36, 243-250. Gavrilova, M. A. (1969). Microbial oxidation of some oil products in the water of the Danube. Gidrobiologiya. 5(3), 24-31. (in Russian) Gealt, M. A. ( 1988). Recombinant DNA plasmid transmission to indigenous organisms during waste treatment. Water Sci. Technol. 20{ll/\2}, 179-184. Geiss, A. & Bourdeaux, J. (1986). Analytical Cheniistty of PCB's. Butterworth Stoneham, Massachusetts. Gerhardt, F. (ed. ). (1984). Methods of General Bacteriology in 3 volumes. Mir Publishers, Moscow, (in Russian) Gocke,K. (1977). Heterotrophic activity. In Microbial Ecology of a Brackish Water Environment (G. Rheinheimer. ed. ). Springer Verlag, Berlin, Heidelberg, New York, (Ecol. Studies 25), pp. 198-222. Goldberg, E. D. ( 1970). Chemical invasion of ocean by man. McCraw-Hill Yearbook, Science and Technology, 280. Goldberg, E. D. ( 1975). Synthetic organohaloides in the seas. Proc. R. Soc. London. 189, 277-279. Gomes, H. R. & Pant, A. (1987). Extracellular products of photosynthesis in a tropical environment. Proc. Indian Nat. Sci. Acad. 53, 4S\^^5. Gorlenko, V. M., Dubinina, G. A. & Kuznetsov, S. I. ( 1977). Ecology of Aquatic Microorganisms. Nauka Publishers, Moscow, 289 pp. (in Russian) Gunkel, W. (1967a). Experimental-oecologische Untersuchungen ueber die limitierenden Faktoren des mikrobiellen Oelabbaues im marinen Mileue. Helgolaender Wiss. Meeresunterr., Bd. 15. (in German) Gunkel, W. (1967b). Arbeitssitzung ueber Gewaesserveroelung. Oelbekaempfung und Oelabbau. Helgolaender Wiss. Meeresunterr., Bd. 16, 285-384. (in German). Gunkel, W. (1968). Bacteriological investigations of oil-polluted sediments from the Cornish coast following the Torrey Canyon disaster. In Biological Effects of Oil Pollutant on Littoral Communities. Field Stud. 2, 96-102. Hagstrom, A., Larsson, U., Horstedt, P. & Normark, S. ( 1979). Frequency of dividing cells, a new approach to the determination of bacterial growth rates in aquatic environments. Appl. Environ. Microbiol. 37, 805-812. Hanson, R. B., Alvarez-Ossorio, M. R., Cal, M. R., Roman, M., Santiago, G., Varela, M. & Yoder, J. ( 1 986a). Planktonic response following a spring upwelling event in the Ria de Arosa, Spain. Man Ecol. Prog. Ser. 32, 101-1 13. Hanson, R. B. & Lowery, H. K. ( 1983). Nucleic acid synthesis in oceanic microplankton from the Drake Passage. Antarctica: evaluation of steady-state growth. Mar. Biol. 73, 79-89. Hanson, R. B., Pomeroy, L. R., Blanton, J. O., Biddanda, B. A., Wainwright, S., Bishop, S. S., Yoder. J. A. & Atkinson. L. P. (1987). Climatological and hydrographic influences on nearshore food webs off southeastern US: Bacterioplankton dynamics. Cont. Shelf Res. 8, 1321-1344. Hanson. R. B., Pomeroy, L. R. & Murray, R. E. (1986b). Microbial growth rates in a cold Gulf Stream eddy of the northwestern Sargasso Sea. Deep-Sea Res. 33, 427-446. Hanson, R. B., Santiago, G. & Cal, M. R. (accepted). Bacterioplankton productivity in an upwelling area off northwest Spain. Mar. Biol. 112 Hanson. R. B., Shefer, D., Ryan, T. H. .. Pope, D. H. & Lowery, K. H. ( 1983). Bacterioplankton in Antarctic ocean waters during late winter; abundance, frequency of dividing cells and estimates of production. Appl. Environ. Microbiol. 45, 1622-1632. Hobble, J. E., Daley. R. J. & Jasper. S. ( 1977). A method for counting bacteria on Nuclepore filters. Appl. Environ. Microbiol. 33. 1225-1228. Ivanov. M. V, ( 1 988 ). Microbiological components of sulphur- carbon cycle in ocean. In Comprehensive Analysisof Natural Environment, pp. 112-116. Transactions of the Soviet- American Symposium. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael, Yu. A., Simonov. A. 1. & Tsyban, A. V. (1980). Scientific aspects of complex investigation of Pacific Ocean waters with the purpose of preventing its pollution. Natural resources of the Pacific Ocean for the welfare of mankind. Moscow, pp. 101-1 16. (in Russian) Izrael. Yu. A. & Tsyban, A. V. ( 1981 ). Monitoring problems and ecological after-effects of ocean pollution. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael. Yu. A. & Tsyban, A. V. (1982). Ecological principles for monitoring state of World Ocean. In All-Round Global Monitoring of Natural Environment Pollutiim. pp. 44-61. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael, Yu. A. & Tsyban, A. V. (1983). About assimilation capacity of the World Ocean. Proceedings of the USSR Academy of Scieiues 252, 702-704. (in Russian) Izrael, Yu. A. & Tsyban, A. V. ( 1985a). Ecology and problems of complex global monitoring of the World Ocean. Transactions of the 1st International Symposium. Gidrometeoizdat Publishers. Leningrad, 1, 19-49. (in Russian) Izrael. Yu. A. & Tsyban. A. V. ( 1 985b ). Atmospheric pollutants transfers and their influence upon ocean-atmospheric interactions. In Ecological After-Effects of Ocean Pollution, pp. 7-27. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael. Yu. A. & Tsyban, A. V. (eds. ) (1987). All-round analysis of the ecological system of the Bering Sea. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael, Yu. A. & Tsyban. A. V. (1988). Methodic Principles of Ocean Complex Ecological Monitoring. Gidrometeoizdat Publishers, Moscow, (in Russian) Izrael, Yu. A. & Tsyban, A. V. ( 1989). Anthropogenic Ecology of Ocean. Gidrometeoizdat Publishers. Leningrad, (in Russian) Izrael, Yu. A. & Tsyban. A. V. (eds. ) (1990). Study of the Bering Sea Ecosystem. Number 2. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael. Yu. A., Tsyban, A. V., Panov, G. V. & Korsak. S. V. (1986). Comprehensive analysis of the Bering Sea ecosystem-monitoring and managing environmental impact. American and Soviet perspectives. Proceedings of the Fifth US-USSR Symposium on Comprehensive Analysis of the Environment, pp. 58-88. (in Russian) Izrael. Yu. A.. Tsyban, A. V.. Panov. G. A.. Korsak. M. N., Kudryatsev. V. M.. Volodkovich. Yu. L. & Chemyak. S. M. ( 1987). Comprehensive Analysis of the Bering Ecosystem. Monitoring and Managing Environmental Impact: American and Soviet Perspectives. National Academy Press, USA, pp. 58-88. Izrael, Yu. A., Tsyban, A. V. & Panov G. V., Korsak, M. N., Kudryatsev, V. M., Volodkovich, Yu. L. & Chemyak, S. M. ( 1 988). Comprehensive analysis of the Bering Sea ecosystem. In Transactions of the Soviet-American Symposium, pp. 77- 111. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael. Yu. A.. Tsyban. A. V., Panov, G. V. & Chemyak, S. M. (1990). Microbial transformation of polychlorinated biphenyls in polar sea regions. DAN USSR (Reports of the USSR Academy of Sciences) 310. 502-506. (in Russian) Izyurova, A. 1. (1950). Rate ofdisintegration of oil products in water and soil. Gigiena i sanitaria 5, 23-28. (in Russian) Joint, I. H. & Pomroy, A. J. ( 1 983). Production of picoplankton and small nanoplankton in the Celtic Sea. Mar. Biol. 77, 19-27. Karasevich, Yu. N. (1982). Fundamentals of Selecting Microorganisms Utilizing Synthetic Organic Compounds. Nauka Publishers, Moscow, (in Russian) Kirchman, D. K.. Ducklow, H. W. & Mitchell. R. (1982). Estimates of bacterial growth from changes in uptake rates and biomass. Appl. Environ. Microbiol. 44, 1296-1307. Kirso, U. E., Stom, D. 1., Belykh, K. I. & Irkha. N. I. (1988). Transformation of Carcinogenic and Toxic Sidistances in the Hydrosphere. 271 pp. Tallinn Publishers, (in Russian) Kohler, H. E., Kohler-Staub, D. & Focht, D. D. (1988). Cometabolism of polychlorinated biphenyls: Enhanced transformation of Aroclor 1 254 by growing bacterial cells. Appl. Environ. Microbiol. 54. 1940-1945. Korsak. M. N. ( 1 985 ). The results of investigations of plankton community in the Bering Sea. In Ecological After-Effects of Ocean Pollution, pp. 56-66. Gidrometeoizdat Publishers. Leningrad, (in Russian) Kottmeier, S. T. & Sullivan, C. W. ( 1987). Late winter primary and secondary production in seawater westof the Antarctica Peninsula. Mar. Ecol. Prog. Ser. 36, 287-298. Kudryatsev, V. M. (1973). Freshly synthesized organic substances discharged by the cells of plankton algae. //;/; Bidl. Biol. Inner Waters 18, 20-24. (in Russian) Kullenberg.G. (1984). The vital seas. Questions and answers about the health of the oceans. UNEP, 28. Kulskyi, L. A.. Savluk, O. S. & Potapchenko, O. G. (1986). Resistance of microorganisms to heavy metals. Water Chem. and Tech. 8(2). 38-43. (in Russian) Kuznetsov, S. J. & Dubinina, G. A. (1989). Methods of Investigating Aquatic Microorganisms. 288 pp. Nauka Publishers, Moscow, (in Russian) Larsson. P. & Hagstrom, A. ( 1 982). Fractionated phytoplankton primary production, exudate release and bacterial production in a Baltic eutrophication gradient. Mar. Biol. 67. 57-70. Larsson, P. & Lemkemeier, K. ( 1 98 1 ). Microbial mineralization of chlorinated phenols and biphenyls in sediment-water system from humic and clear-water lakes. Water Res. 23, 1081-1085. Le Petet, I., N'Guyen. M. H. & Tagger, S. (1977). Quelques donnees sur I'ecologie d'une zone marine littorale les relets d'une raffinerie de petrole. Environ. Pollut., 13. (in French) 113 Linton, A. H.( 1988). Plasmids in the environment. Schriftens. Ver. Wasser, Boden and Lufthyg, No. 78, pp. 197-224. Liu, D. (1980). Enhancement of PCB's biodegradation by sodium linginsulfonate. Water Res. 14, 1467-1475. Loprieno, N. ( 198 1 ). Short term tests to assess the mutagenic and carcinogenic hazards of new chemicals. Biol. Int. 3, 2-14. Mameava, N. V. (1987). Compositions and quantitative distribution of infusoria in the Pacific pelagic area. In Comprehensive Analysis of the Bering Sea Ecosystem. pp. 174-192. Gidrometeoizdat Publishers, Leningrad. (in Russian) McMans, G. G. & Peterson, W. P. ( 1988). Bacterioplankton production in the nearshore zone during upwelling of central Chile. Mar. Ecol. Prog. Ser. 43, 11-17. Mironov,O.G.( 1970a). Effect ofpollution on marine organisms and the process of selfpurification of the marine environment. In The Study of the Baltic Sea. Thesis report, Riga, 29 pp. (in Russian) Mironov, O. G. (1970b). On the role of microorganisms growing on oil, in self-purification and indication of oil pollution in the sea. Oceanology 10(5), 820-827. (in Russian) Mironov, O. G. (1985). The Interaction of Marine Organisms with Petroleum Hydrocarbons. Gidrometeoizdat Publishers. Leningrad, 127 pp. (in Russian) Newell, S. Y. & Christian, R. R. ( 1981). Frequency of dividing cells as an estimator ofbacterial productivity. A/?/)/. Environ. Microbiol. 42, 23-3 1 . Newell, S. Y. & Fallon, R. D. ( 1982 ). Bacterial productivity in the water column and sediments of the Georgia (USA) coastal zone: Estimates via direct counting and parallel measurement of thymidine incorporation. Microb. Ecol. 8, 33-46. O'Connor, J. M. & Huggett, R. (1988). Aquatic pollution problems North Atlantic coast, including Chesapeake Bay. . Aqiiat. To.xicol. 11, 163-190. OilintheSea(1985). Inputs, fates and effects. MARPOLMON Report. Nat. Acad. Press, Washington, D.C. Oliver. J. D. (1982). Taxonomic scheme for the identification of marine bacteria. Deep Sea Research 29(6A), 795-798. Oppenheimer, G. H., Gunkel, W. & Gassman. G. (1977). Microorganisms and hydrocarbons in the North Sea during July-August 1975. In Proceedings Oil Spill Conference. American Petroleum Institute. Washington D.C, pp. 593-610. Overbeck,J.( 1974). Microbiology and biochemistry. Mitt Int. Limnol. 20, 198-228. Pearson.C. R.(1983). Halogenated aromatic. In Environmental Handbook Part B, pp. 89-1 16. Pelleroni. N. Y. ( 1975). General properties and ta.xonomy of the genus Pseudonumas — genetic and biochemistry of Pseudomonas. pp. 1-36. New York. Platpira, V. P. ( 1982). Results of microbiological monitoring in the Gulf of Riga. In Environment and Hydrobiocenoses of the Gulf of Riga. Riga: Zmantne. pp. 76-92. (in Russian) Platpira V. P. (1985). Microflora and transformation of petroleum hydrocarbons in the marine environment. Riga: Zinantne, 162 pp. (in Russian) Piatt, J. (1984). Primary productivity in the central North Pacific comparison of oxygen and carbon fluxes. Deep-Sea Re.'i. 31. 1311-1319. Pomeroy, L. R. & Deibel, D. ( 1986). Temperature regulation and bacterial activity during the spring bloom in Newfoundland coastal waters. Science 233, 359-361 . Pravdic, V.(1981). GESAMP. The first dozen years. UNEP, 93. Razumov, A. S. ( 1932). Methodics for direct calculation of bacteria in water. Its comparison with the method of Koch. Microbiology 1, 131-136. Rheinheimer, G. (ed. ) (1977). Regional and seasonal distribution ofbrackish water environment. Springer Verlag, Berlin, Heidelberg, New York. (Ecol. Stud. 25), 121-137. Rheinheimer, G. H. (1986). Influence of eutrophication on bacterial abundance and activity in the Baltic Sea. In Integrated Global Ocean Monitoring. Proceedings of the First International Symposium. Gidrometeoizdat Publishers, Leningrad, 2, 280-286. Riemann, B., Nielsen, P., Jeppcsen, M., Marcussen, B. & Fuhrman, J. A. ( 1984). Diel changes in bacterial biomass and growth rates in coastal environments, determined by means of thymidine incorporation into DNA, frequency of dividing cells (FDC), and microautoradiography. Mar. Ecol. Prog. Ser. 17, 227-235. Riemann, B., Bjomsen, P. K., Newell, S. & Fallon, R. (1987). Calculation of cell production of coastal marine bacteria based on measured incorporation of ['H]thymidine. Limnol. Oceanogr. 32, 471-476. Rochelle. P., Fry, J. C. & Day. M. J. (1989). Factors affecting conjugal transfer of plasmids encoding mercury resistance from pure cultures and mixed natural suspensions of epilithic bacteria. J. Gen. Microbiol. 135(2), 409-424. Rodoff, M. (1961). Oxidation of aromatic compounds by bacterial. Appl. Microb. 3, 193-221. Romanenko, V. J. (1964). Heterotrophic assimilation of CO, by bacterial flora in water. Microbiology 33, 679-683. (in Russian) Romanenko, V. J. ( 1965). Ratio of oxygen and carbonic acid uptake in heterotrophic bacteria with peptone culturing. Microbiology 35, 397-402. (in Russian) Romanenko, V. J. (1985). Microbiological Processes and Decomposition of Organic Matter in Internal Waters. Nauka Publishers, Leningrad, (in Russian) Romanenko, V. J. & Kuznetsov. S. J. (1974). Freshwater Microorganisms Ecology. A Laboratory Hatulbook. Nauka Publishers. Leningrad, 194 pp. (in Russian) Sahasrabudhe, S. R. & Modi, V. V. (1987). Microbial degradation of chlorinated aromatic compounds. Microbiol. Set. 4, 300. Saijo, Y., Mitamura, O. & Ogiyama. K. (1974). Chemical composition of surface film in the coastal sea area and in freshwater lakes. Jpn. J. Limnol. 35. 110-116. Sayler, G. S.. Shon, M. & Colwell. R. R. ( 1977). Growth of an estuarine Pseudomonas sp. on polychlorinated biphenyl. M/c7-<;/;.£fo/. 3. 241-255. 114 Schmidt, T. & Schlegal, G. ( 1 989 ). Nickel and cobalt resistance of various bacteria isolated from soil and highly polluted domestic and industrial waters. FEMS Microbiol. Ecol. 62(3), 315-328. Seki, H. (1982). Organic materials in aquatic ecosystems. CRC Press, Inc., Boca Raton, Florida. Seki, H. (1986). Thresholds in eutrophication of natural waters. Environ. Monit. A.wt'.v.v. 7, 39-46. Shields, M.S., Hooper. S. W. & Sayler, G. S. ( 1 985 ). Plasmid- mediated mineralization of 4-chlorobiphenyls. J. Bacteriol. 163. 882-889. Shewan, Y. M., Hobbs, Y. & Hodkiss, W. A. (1960). A determinative scheme for the identification of certain genera of gramnegative bacteria with special reference to the Pseudomonadaceae. J. Appl. Bacteriol. 23, 379-390. Shpolski, E. v., Ilyin, A. A. & Klimov. L. A. (1952). Fluorescence spectra of coronene in frozen solutions. Transiictiou.^ of USSR Academy of Sciences 87, 935-939. (in Russian) Shtukova, Z. A. ( 1990). Bacterioplankton of the Baltic Sea in 1987. In Ecosysiem Investigation of the Baltic Sea, Issue 3. pp. 58-68. Gidrometeoizdat Publishers, Leningrad. (in Russian) Sieburth, Y. ( 1979). Sea Microbes. Oxford University Press, New York. Slater, E. E., Anderson, M. D. & Rosenkranz, H. J. (1971). Rapid detection of mutagens and cancerogens. Cancer Res. 31,907-973. Sorokin, Yu. J. (1971 ). Quantitative assessment of the role played by bacterioplankton in biological productivity of the Pacific tropical waters. In Functional Activities of Pelagic Communities in Trophic Regions of the Ocean, pp. 92-1 22. Nauka Publishers, Leningrad, (in Russian) Sorokin, Yu. J. ( 1980). Bacterioplankton. Bacterial production and degradation of organic matter. In Ecosystetn of the Pelagial of the Peruvian Region, pp. 104-115. Nauka Publishers, Moscow, (in Russian) Sorokin, Yu. J. ( 1982). The Black Sea. Nature and Resources. Nauka Publishers, Moscow, 216 pp. (in Russian) Sorokin. Yu. J. (1984). Bacterioplankton and primary production in the central part of the Indian Ocean. Biology of the Sea 2, 3-19. (in Russian) Sorokin, Yu. J. (1985). Bacteria and microzooplankton production. In Biological Resources of the Ocean. pp. 71-86. Agropromizdat Publishers. Moscow. (in Russian) Sorokin, Yu. J. & Kadota. H. (1972). Microbial production and decomposition in freshwaters. p. 1 12. Blackwell Publishers. London. Subramanian. B. R., Tanabe, S., Hidaka, N. & Tatsukawa. R. ( 1983). DDT and PCB isomers and congeners in Antarctic fish. Arch. Environ. Contain. Toxicol. 12,621-626. Tanabe, S. (1984). PCB in the western North Pacific. Arch. Environ. Contain. Toxicol. 13.731-738. Tanabe, S. (1985). Distribution, behavior, and fate of PCB in the marine environment. J. Occanogr. Soc. Jpn.. 41(5), 358-370. Treccan, V. ( 1963). Microbial degradation of hydrocarbons. Prog. Ind. Microbiol A, 1-33. (in Russian) Tsyban, A. V. ( 1970). Bacterioneuston and bacterioplankton of the Black Sea shelf zone. Naukova Dumka, Kiev 276. (in Russian) Tsyban, A. V. (ed. ) ( 1980). Manual for Methods of Sea Water and Bottom Sedimentations Biological Analysis. Gidrometeoizdat Publishers, Leningrad pp. 8-79. (in Russian) Tsyban, A. V. (1981). Methods of calculating microbial degradation of petroleum hydrocarbons. In Study of the Baltic Sea Eco.system 1. 61-68. Tsyban, A. V., Abalikhin, T. A. & Barinova, S. P. (1973). Microorganisms as a factor of pollution and self-purification processes in coastal water areas. Sanitaryprotection of seas and sea coasts. Transactions of Scientific and Practical Conference. Sukhumi, (in Russian) Tsyban, A. V., Korsak. M. N., Kudryatsev, V, M., Panov, G. V. & Azhipa, O. Ya. (1987a). Bacterial production and decomposition of organic matter. In Comprehensive Analysis of the Bering Sea Ecosystem, pp. 89-97. Gidrometeoizdat Publishers, Leningrad, (in Russian) Tsyban, A. v., Kudryatsev, V.M.,Mamaev,V.O. &Sukhanova, N. V. (1992). Total number, biomass and activity of bacterioplankton of the Bering and Chukchi Seas (Subchapter 4. 1. 1, this volume). Tsyban, A. V., Kudryatsev, V. M, & Panov, G. V. (1987b). Total amount and biomass of bacterial population. In Comprehensive Analysis of the Bering Sea Ecosy.stein. pp. 81-89. Gidrometeoizdat Publishers, Leningrad, (in Russian) Tsyban, A. V.. Panov. G. V. & Kudryatsev. V. M. (1987c). Distribution and quantitative composition of heterotrophic microorganisms, oxidizing organic polluting substance. In Comprehensive Analysis of Ecological System of the Bering Sea. pp. 97-1 1 1. Gidrometeoizdat Publishers. Leningrad. (in Russian) Tsyban, A. V.. Panov. G. V.. Kudryatsev. V. M.. Mikhailov, V. v., Lycheva.T. A. & Azhipa,0. Ya. (1990). Microorganisms and microbiological processes. In Ecosystem Investigation of the Bering Sea. issue 2, pp. 198-252. Gidrometeoizdat Publishers, Leningrad, (in Russian) Tsyban, A. V., Panov, G. V., Subbotin, V. G., Timoshenkova, N. P. & Chemyak, S. M. (eds. ) (1988). Methodological Foundations of Integrated Ecological Monitoring of the Ocean. Gidrometeoizdat Publishers, Moscow, 288 pp. (in Russian) Tsyban, A. V., Panov, G. V., Ventzel. M. V., Volodkovich. Yu. L. & Korsak, M. N. (1986). Long-term period ecological investigations in impact and background regions of the World Ocean. In Complex Global Monitoring of State of Biosphere, Vol. 3, pp. 45-60. Gidrometeoizdat Publishers, Leningrad, (in Russian) Tsyban. A. V., Volodkovich, Yu. L. & Belyaeva, O. L. ( 1 987d). Studying of benzo(a)pyrene circulation in the Bering Sea. In Comprehensive Analysis of the Ecological System of the Bering Sea, pp. 218-232. Gidrometeoizdat Publishers, Leningrad, (in Russian) Tsyban, A. V.. Volodkovich, Yu. L., Panov, G. V., Khessina, A. Ya. & Yermakov, Ye. A. (1985). Distribution and microbial degradation of carcinogenic hydrocarbons in some U5 regions of the World Ocean. In Ecological Consequences of Ocean Pollution, pp. 88-1 12. Gidrometeoizdat Publishers. Leningrad, (in Russian) Tsyban, A. V., Volodkovich, Yu. L. & Pfeiffere. M. Yu. (1985). Circulation of the contaminants in the Baltic Sea ecosystem. Investigation of the Baltic Sea ecosystem. Gidrometeoizdat Publishers, Leningrad, pp. 244-257. Tuistra, L. G, M. T. & Traag, W. A. (1983). Capillary gas chromatographic-mass spectrometric determination of individual chlorobiphenyls in technical Aroclors. / Assoc. Off. Anal. Chem. 66. 708-717. Turley, C. M. & Klochte, K. (1985). Direct measurement of bacterial productivity in stratified waters close to a front in the Grish sea. Mar. Ecol. Progr. Ser. 23, 209-219. Unterman, R., Bodard, D. L., Bopp, L. H., Johnson, C. & Haberl, M. L. (1985). Microbial degradation of PCB. In Proceedings: International Conference on New Frontiers for Hazardous Waste Management, pp. 481-488. U. S. Environmental Protection Agency, Cincinnati, Ohio. Vieble, W. J. ( 1984). Aquatic microbial ecology - research questions and opportunities. Trans., Ecol. Res. 1980. Proc. NATO ARW and INTECOL Workshop Future and Use Ecol. Decade Environ. New York. London, pp. 35^9. Vinogradov, M. E. & Shushkina, E. A. (1989). Macroscale distribution of quantitative characteristics of plankton in the Pacific. Oceanology 19. 121-125. (in Russian) Volodkovich, Yu. L. & Belyaeva, O. L. ( 1987 ). Biogeochemical cycles of benzo(a)pyrene in the Bering Sea ecosystem. In Proceedings of the Third Congress of Soviet Oceanologists, Vol. 1, pp. 91-93. Gidrometeoizdat Publishers, Leningrad, (in Russian) Voroshilova, A. A. & Dianova, E. V. (1950). On bacterial oxidation of oil and its migration in natural water bodies. Microbiology 19(3), 38-45. (in Russian) Voroshilova, A. A. & Dianova, E. V. (1952). Petroleum- oxidizing bacteria - indicators of the intensity of biochemical oxidation of petroleum under natural conditions. Microbiology 2\(A). 14-22. (in Russian) Yegerov, N. S. (ed. ). ( 1983). Manual for Practical Studies in Microbiology. Moscow State University, USSR, pp. 5-146. 116 Chapter 5: PLANKTON Editors: MIKHAIL N. KORSAK & C. PETER McROY Subchapter 5.1: Phytoplankton 5.1.1 Certain Characteristics of Phytoplankton MIKHAIL V. VENTSEL and NATALIA P. VASJUTINA Institute of Global Cliimite and Ecology, State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR Introduction This report presents results of the preliminary analysis of phytoplankton samples collected during the Third Joint US-USSR Bering & Chukchi Seas Expedition. The specimens were observed by the "living droplet" method using a light microscope. We determined the species composition of the microalgae, their size, and the number of cells. As a result, we have quantitative estimates of the total number and biomass of phytoplankton per unit volume. In addition, dominant species have been identified, since their development in the plant community strongly influences the value of the quantitative indices mentioned before. These results are shown in Table 1 . Distribution of phytoplankton was determined in the following regions: the Chirikov basin (Stations 87-107), the Gulf of Anadyr ( Stations 9^ 1 ). the central Bering Sea region (Stations 1-7), and the southern Bering Sea region (Stations 108-113). An intensive development of phytoplankton was observed in the Chirikov basin. The number and biomass of microalgae were high at all stations. The total number in the surface layer varied in the range of 500-1,700 x 10' cells/1, and the highest value was observed at Station 86. Total numbers of phytoplankton were dominated by diatoms: Leptocylindrus daniciis, Chaetoceros socialis. Chaetoceros debilis, and Rhizosolenia alata. Biomass at the surface varied in the range of 300-3,000 mg/1. The largest contribution to the total biomass was also due to diatoms: Leptocylindrus danicus, Rhizosolenia alata. and Chaetoceros concavicornis. At all stations in the Chirikov basin, the quantitative indices decreased with the depth. The only exception was Station 1 06. where the number and biomass were high at a depth of 45 m as well. In general at 40—45 m, the numbers varied in the range of 80-1,000 X 10' cells/1, and biomass — 120-850 mg/1. Thus, in the Chirikov basin an intensive development of phytoplankton was observed, with diatoms occupying a leading position in the plant community. In the Gulf of Anadyr, phytoplankton were not as abundant as in the Chirikov basin and their numbers varied in a smaller range, from 100 to 700 x 10' cells/1. At many stations, the number of phytoplankton increased with the depth (Stations 15, 19,32,36). This was probably connected with the presence of the pycnocline at these depths. The most numerous species in the plant community of the Gulf of Anadyr were algae of various classes: Class Bacillariophyceae — Fragilaria oceanica, Fragilaria striatula, Chaetoceros compressus, Chaetoceros socialis, Leptocylindrus danicus. Class Dinophyceae Class Chrysophyceae Gymnodinium wulffii, Goniaulax orientalis. Chromulina sp. Biomass of phytoplankton in this region varied over a wide range from 6 to 3,600 mg/1. High values of biomass were caused by the presence of large diatoms like Rhizosolenia alata. Amphiprora hyperborea, and Coscinodiscus oculus iridis in the plant community. In general, it may be noted that during the period of the expedition, the phytoplankton composition of the Gulf of Anadyr was very diverse. While the number of microalgae was evenly distributed throughout area, there was a wide range in the biomass values. This was connected with the presence of large forms of phytoplankton in the samples. There was an uneven distribution of phytoplankton in the central area of the Bering Sea. The phytoplankton numbers in the surface waters varied in the range of 100-2,400 X 10' cells/1 and biomass in the range of 40-1,800 mg/1. Quantitative indices decreased with depth, which was characteristic for all the central area stations, except for Station 7. At this station, the number and biomass of phytoplankton were roughly uniform with depth. Most abundant vegetation in this region consisted of small forms. The taxonomic composition of phytoplankton is characteristically depauperate in diatoms as compared with the northern part of the sea. The following species were numerically dominant: Class Chrysophyceae — Chromulina sp. Class Haptophyceae — Calyptrosphaera insignis. Class Xanthophyceae — Meringosphaeramediterranea. Class Cyanophyceae — Synechococcus sp. Class Loxophyceae — Pedimonas mikron. Class Bacillariophyceae — Fragilaria striatula, Chaetoceros debilis, Nitzschia delicatissima. In the southern part of the Bering Sea, phytoplankton was characterized by the following: their numbers at the sea surface varying in the range of 700-1, 700 X 10' cells/1. Among numerically dominant species there were no diatoms or peridinians. Instead, representatives of the following classes of algae were most abundant in this region: Class Cyanophyceae — Synechococcus sp. Class Loxophyceae — Pedimonas mikron. Their biomass ranged from 3 to 1,300 mg/1. As for biomass, the following species of microalgae were dominant: Class Bacillariophyceae — Fragilaria striatula. Chaetoceros concavicornis. 121 TABLE The number, biomass. and dominant species of phytoplankton. Sta. Depth Number Biomass No. cells/1 mg/1 1 0 1 84.600 264.6 10 87.414 5.3 20 132.600 266.3 25 60.452 6.2 45 51.435 4.0 2 0 2,440,800 1.824.8 45 39.000 19.9 3 0 106.600 208.3 10 648.960 130.6 45 23.400 5.1 4 0 590.200 1.458.3 15 477.100 484.7 45 68.900 127.7 5 0 285.243 333.5 15 38.592 14.2 45 146.523 102.6 6 15 469.300 215.5 7 0 183.300 43.5 45 104,907 45.5 128 267,800 71.7 9 0 678,000 106.4 32 610,200 54.6 88 16,250 5.8 11 135 71,961 23.4 13 0 3,651,596 26.3 130 119,646 73.8 15 0 96,030 7.4 42 185,600 47.1 19 0 153.600 211.9 55 374.400 56.3 24 0 363.200 32.1 45 214.400 13.6 27 0 316.800 3.640.1 45 374.400 334.8 32 0 463.078 56.6 45 610.324 71,3 35 0 224,070 23.9 45 277,420 171.0 36 0 126.973 18.7 45 313.698 151.2 41 0 742.632 2.584.5 45 83.226 123.5 83 0 496.000 269.0 86 0 1.740.800 3.158.0 89 0 912.000 2.654.x 45 281.600 521.3 96 0 953.600 937.8 40 1 .046.400 850.2 ino 0 1,148.800 2.934.2 102 0 486.400 3.109.7 lOX 0 651.600 2.7 45 1 .248.000 54.1 110 0 1.667.200 1,3.^9.2 112 0 1.420.800 131.5 45 358,40(1 82.2 113 0 1,324,80(1 121.5 45 1,244.800 73.2 Dominant Species Numerically Biomass Fragilaria striatula Chromitlinales sp. Synechococcus sp. Meringosphaera meditenanea Synechococcus sp. Chaetoceros debilis Synechococcus sp. Fragilaria striatula Synechococcus sp. Synechococcus sp. Chaetoceros debilis Nitzschia delicatissima Chaetoceros debilis Fragilaria striatula Chromulina sp. Fragilaria striatula Fragilaria striatula Fragilaria striatula Fragilaria striatula Fragilaria striatula Chromulinales sp. Chromulincdes sp. Chromulinales sp, Chroomonas sp. Chromulinales sp. Chroomonas sp, Synechococcus sp. Chroomonas sp. Pnmnesiides sp. Svnechoccus sp. Thalassiosira nordenskioeldii Phaeocystis pouchettii Phaeocystis pouchettii Fragilaria oceanica Phaeocystis pouchettii Phaeocystis pinichetiii Prvmnesiales sp. Chaetoceros compressus Phaeocystis pouchettii Chaetoceros socialis Leptocylindrus danicus Phaeocystis pouchettii Chroomonas sp. Chaetoceros socialis Chaefoceros subsecundus Leptocylindrus danicus Chaetoceros socialis Chaetoceros socialis Chaetoceros debilis Leptocylindrus danicus Pedimonas tnikron Synechococcus sp. Synechococcus sp. Synechococcus sp. Synechococcus sp. Synechococcus sp. Synechococcus sp. Amphiprora hyperborea Chromulinales sp. Amphyprora hyperborea Meringosphaera mediterranea Meringosphaera mediterranea Chaetoceros debilis Chaetoceros debilis Amphiprora hyperborea Calyptrosphaera insignis Chaetoceros debilis Chaetoceros concavicornis Chaetoceros concavicornis Rhizosolenia alata Coretron criophyllum Calyptrosphaera insignis Leptocylindrus danicus Fragilaria striatula Fragilaria striatula Denticulopsis seminea Fragilaria striatula Goniaulux orientalis Gymnodmium sp. Eucampia zoodiacus Distephanus speculum Chromulinales sp. Amph i roroa hype rbo rea Gymnodinium nuljfi Leptocylindrus danicus Rhizosolenia alata Leptocylindrus danicus Thalassiosira nordenskioeldii Gymnodinium wulffi\ Coscinodiscus oculus-iridis Fragilarai oceanica Dinohryon balticum Gymnodinium wulffii Goniaulax orientalis Chaetoceros compressus Gymnodinium wuljfii Chaetoceros socialis Leptocylindrus danicus Leptocylindrus danicus Rhizosolenia alata Chaetoceros concavicornis Leptocylindrus danicus Leptocylindrus danicus Leptocylindrus danicus Leptocylindrus danicus Leptocylindrus danicus Leptocylindrus danicus Hemiselmis sp. Distephanus speculum Chaetoceros concavicornis Fragilaria striatula Fragilaria striatula Gymnodinium wulffii Distephanus speculum ill Class Dinophyceae — Gyiuncdiniuni wiiljfii. Class Cryptophyceae — Hemiselmis sp. Class Chrysophyceae — Disteplunuis speculum. Thus, due to large ceil sizes, representatives (it both diatoms and peridinians dominated the biomass. In general, the following relationships in distribution of qualitative and quantitative characteristics of phytoplankton in the Bering Sea, in 1988, were noted: /. Depletion of the diatom and peridinian flora from north to south, which can be attributed to the seasonal succession of phytoplankton. 2. As for quantitative indices, they were subject to sharp variations both from station to station and at different depths, which was characteristic for the region under investigation, being hydrologically complex. 5.1.2 Phytoplankton Biomass Distribution in the Northern Bering Sea and Southern Chukchi Sea WILLIAM S. ROBIE. C. PETER MCROY. and ALAN M. SPRINGER liisiiiulf of Marine Science, University af Alaska. Fairbanks. Alaska. USA Introduction The ecosystem of the northern Bering Sea and southern Chukchi Sea Shelf region is strongly influenced by the advection of cold, nutrient-rich seawater from the edge of the deep Bering Sea basin ( Springer. 1988). This conclusion resulted from data collected by Inner Shelf Transfer and Recycling (ISHTAR) Project investigators between 1983 and 1989 (Walsh et ai, 1989). The project was the first large-scale scientific study attempting to elucidate the ecological processes of these northern shelf waters, aregion of extremely high primary and secondary productivity (McRoy et ai, 1972: Motoda & Minoda. 1974: Sambrotto et ai.. 1984: Springer. 1988) leading to high upper trophic level productivity (Hood & Kelley, 1974). The Third Joint US-LISSR Bering & Chukchi Seas Expedition, aboard iheAkadeinik Korolev. provided the first opportunity to extend the ISHTAR experimental design across the whole northern shelf area to examine the areal and vertical distribution of phytoplankton biomass. Historical studies of the Bering Sea region show high productivity associated with the continental shelf area in the southeastern Bering Sea ( Banahan & Goering. 1 986: Sambrotto et ai. 1986: Schneider et al.. 1986: Smith & Vidal. 1986; Walsh & McRoy. 1986) and in Bering Strait (McRoy et al., 1972;Motoda& Minoda. 1974:Iverson<'/«/.. 1979). Zenkevitch ( 1 963 ), working with many years of Soviet data, proposed that cold oceanic water from the North Pacific Ocean and warm shelf water from the southeastern Bering Sea create an east- west biogeographical division in the northern shelf region. A Japanese study by Motoda and Minoda ( 1974) also described zoogeographic associations in the pelagic fauna with cold and warm water masses. Kinder ef a/. (1 975) described the Bering Slope Current system as a northwest, subsurface flow of North Pacific Ocean water entering through the Aleutian Islands and continuing along the continental shelf slope bisecting at Cape Navarin to form the Anadyr Stream. Takenouti and Ohtani (1974) and Coachman et al. (1975) described the northern Bering Sea as consisting of three distinct water masses: Alaskan Coastal, Bering Shelf, and Anadyr water. Productivity and chlorophyll data from McRoy et al. (I972),Sambrottoe?fl/.( 1984). Springer( 1988). and Whitledge etal. ( 1988) showedextremely high phytoplankton production in the northern Bering Sea and southern Chukchi Sea. Benthic studies (Zenkevitch. 1963; Alton. 1974; Grebmeier et al.. 1988; Grebmeier & McRoy, 1989) revealed rich benthic fauna in this region, also indicating a persistent system of intense primary production in the overlying water. These studies led to the hypothesis that advection of cold, nutrient-rich, oceanic water (Anadyr water) onto the continental shelf of the northern Bering and southern Chukchi Seas fueled the high primary productivity (Walsh t'/fl/.. 1989). This production regime has been described as a "continuous culture" system analogous to an upwelling regime (Sambrotto et al., 1984). Prior to 1988, the data set describing the production associated with this flow was confined to the waters east of the US-USSR convention line. The joint US-USSR expedition allowed expansion of the data set across the entire shelf (see Frontispiece) to include the core of the Anadyr Stream. Study Area The study area extended from the South Polygon (53°N, 175°E) in the southern Bering Sea to the southeastern Chukchi Sea near Cape Lisburne (69°N, 167°W: Frontispiece). Ecological investigations began at the East Polygon (58°N, 1 75° W; Stations 1-5) and continued in the Gulf of Anadyr and 123 the Bering Shelf area southwest of St. Lawrence Island (Stations 6-43). After investigation of Anadyr Strait, the expedition proceeded north into the Chukchi Sea (Stations 44-75). After completing the studies in the Chukchi Sea, Bering Strait was surveyed twice (Stations 76-86). Proceeding south from the Bering Strait, studies were undertaken in the Chirikov basin (Stations 87-107) and the southern Bering Sea (Stations 108-1 13). including the South Polygon. Materials and Methods Phytoplankton biomass was assessed at each station in the Bering and Chukchi Seas as chlorophyll a fluorescence ( Parsons etai, 1984). Briefly, water samples (250 ml) were collected at 11 depths from each station using Niskin bottles attached to a rosette sampling apparatus. Samples were filtered through 25 mm Gelman glass fiber filters (pore size: 0.3 \im) in a multiple-sample filtration apparatus using a vacuum pump. Each filter was suctioned dry and then placed in a 20-ml glass test tube with 1 0 ml of 90% acetone to extract the photosy nthetic pigments. To facilitate extraction of all pigments, a tissue grinder was used to homogenize the filter in acetone. The sample was then transferred to a 15-ml centrifuge tube and centrifuged for 10 min. After centrifugation, the supernatant was transferred to a cuvette, where its fluorescence was measured using a Turner Designs fluorometer before and after acidification with two drops of 5% HCl. For analysis, chlorophyll data from stations on the shelf south of St. Lawrence Island, in the Gulf of Anadyr, and in the polygon stations were integrated from the surface to 50 m to give areal chlorophyll values. In the Chirikov basin and Chukchi Sea where the bottom is less than 50 m deep, chlorophyll values were integrated from surface to bottom. Results Chlorophyll concentrations were measured at each of the 113 stations studied during the cruise from 27 July to 2 September 1988. Samples for chlorophyll analysis were obtained at approximately 10 discrete depths at each station. Over 1,000 samples were collected and analyzed in this comprehensive study of the Bering and Chukchi Seas. Central Bering Sea Polygons The East and South Polygons each consist of five stations in the deep Bering Sea. The polygon stations are part of a continuing study and were included in the Second Joint LTS- USSR Bering Sea Expedition in 1984. East Polygon. Stations 1 to 5 were located in the East Polygon ( 58°N, 1 75° W) over the shelf slope area in the eastern Bering Sea (Frontispiece). Bottom depth at these stations ranged from 140 m at Station 5 to 3,190 m at Station 3. Integrated chlorophyll values ranged from 22 mg/m- at Station 5 to 121 mg/m- at Station 2. The average for all stations was 66 mg/m-. Deep-water (2,689 m and 3,190 m) Stations 2 and 3 had the highest values, 1 2 1 and 90 mg/m-, respectively, with the lowest values 22 and 48 mg/m-, being found at the shallower ( 140 m and 150 m) shelf-slope Stations 5 and 4, respectively. South Polygon. Stations 108 to 1 13 were located in the South Polygon (53°N, 175°W) in the deep basin of the Bering Sea over Bowers Ridge ( Frontispiece). The minimum depth at these stations is 220 m. Integrated chlorophyll values were less than 30 mg/m- at each station with the exception of Station 1 1 2 (67 mg/m-). The average for all stations was 35 mg/m-. Gulf of Anadyr and Western Bering Shelf Stations 7 to 43 were located in the Gulf of Anadyr and on the adjacent shelf southwest of St. Lawrence Island (Frontispiece). Integrated chlorophyll ranged from 13 mg/nr at Station 1 2, east of Cape Navarin outside the Gulf of Anadyr, to 797 mg/m- at Station 24 in the central region of the gulf (Fig. 1). Relatively low values (13 to 45 mg/m-) characterized the southern half of the study area, particularly the shelf area south of St. Lawrence Island. High values were measured near the northern coast of the Gulf of Anadyr. Stations 24 and 26 had exceptionally high concentrations of 797 mg/m- and 430 mg/m-, respectively. These were some of the highest values measured during the cruise. Station 26 had chlorophyll concentrations greater than 50.0 mg/m' in the top 10 meters, decreasing to less than 1.0 mg/m' below 20 meters (Fig. 2b). Fig. 1 . Depth integrated ((l-?0 m) chlorophyll (mg chl ii/nr ) lor Akademik Korolev stations. The highest chlorophyll values were found in the north and central Gulf of Anadyr with concentrations decreasing to the south and east (Fig. 1 ). A cross section, from Station 26 in the northwest comer of the gulf to Station 35 on the adjacent shelf area south of Anadyr Strait, shows a subsurtace chlorophyll maximum (>15.0 mg/m') located along the northern coast of 124 e) b) a) 87 88 STATIONS 89 90 91 0 30 60 90 97 98 99 100 101 20 02 0 15 26 27 28 30 45 60 29 32 33 34 35 325 430 38 39 107 100 200 300 DISTANCE 400 (km) 490 Fig. Vertical c 10 North ( ross-sections of chlorophyll (mg/m') arranged from South a to e). Transect location given on Frontispiece. the gulf at a depth of 20 to 30 m (Fig. 2b). A cross section from Station 1 3 to .Station 39, from the outer shelf ( 1 50 m) to Anadyr Strait (30 m), reveals high phytoplankton biomass strictly limited to the strait area providing evidence of the influence of nutrient-rich Anadyr water (Fig. 2a). Anadyr Sirail Data from Anadyr Strait indicate that high integrated chlorophyll values were associated with waters near the Siberian coast at Station 39 ( 193 mg/m-). Values decreased to the east to 23 mg/m- at Station 43 next to St. Lawrence Island (Fig. 1). A cross-section of Anadyr Strait provides another view of the association between phytoplankton stocks and Anadyr water. Chlorophyll concentrations decrease to less than 1.0 mg/m' across the eastern half of the strait (Fig. 2c). Chihkov basin Stations 87 to 1 07 were in the Chirikov basin (Frontispiece). Data from this area revealed high chlorophyll values on the western side of the basin, suggesting the presence of higher nutrient water (Fig. 1 ). Integrated chlorophyll values as high as 593 mg/m-, at Station 87, were observed close to the Soviet coast. The western side of the basin is characterized by values over 100 mg/m-. Chlorophyll values decrease to the east across the basin. Phytoplankton biomass of less than 50 mg/m- was characteristic of the eastern side of the basin in Alaska Coastal water. The maximum eastward extent of high chlorophyll values was observed in the central part of the basin at Station 94 (307 mg/m-). Data from a transect across the central basin, from stations 97 to 102, shows distinct areas of high biomass, one next to the Soviet coast and one in the central part of the basin (Fig. 2d). The western concentration has a subsurface chlorophyll maximum (>3.0 mg/m') at 10 to 15 m while the eastern area has a maximum (>8.0 mg/m') at 20 to 25 m. These two areas of high biomass lose their identity and converge with the water masses flowing toward Bering Strait (Fig. 2e). The highest concentration of chlorophyll in the Chirikov basin was measured at Station 87 the closest station to the Soviet coast. Bering Strait Bering Strait was surveyed twice. The first transect occupied six stations (76-8 1 ) across the strait while the second transect occupied five of the same stations (82-86), omitting only the westernmost station. Integrated values of chlorophyll indicate the same pattern for both transects (Fig. 1 ). Highest values, up to 619 mg/m- at Station 76, were observed adjacent to the Soviet coast west of Ratmanov Island and the lowest value ( 27 mg/m- at Station 8 1 ) occurred east of Diomede Island near the Alaskan coast. During the first passage, the chlorophyll maximum on the western side of the strait (>25 mg/m') was at the surface at Station 76 (Fig. 3a). On the eastern side of the strait there were noconcentrationshigherthan 1.7mg/m'. Although the western side of the strait showed high integrated values throughout the water column, most phytoplankton were close to the Soviet coast. In the second transect a similar pattern existed as in the first with the exception of a subsurface maximum (8.0 mg/m') on the western side at 30 m. Bottom concentrations on the eastern side near Diomede Island appear to match bottom 125 d) c) concentrations next to the islands on the western side indicating that some of the phytoplankton associated with Bering Shelf- Anadyr water flowed through the eastern portion of the strait. Chukchi Sea Stations 44 to 75 were in the southern Chukchi Sea (Frontispiece). The highest values of integrated chlorophyll (625, 696, and 1,167 mg/m-) found during the cruise were ^/ observed at stations 54, 56, and 55, respectively. Values in excess of 300 mg chl/m- characterized the majority of these stations with the highest values found in the center of the region (Fig. 1). Thirteen of the 31 stations, all in the center of the region or near the Soviet coast, had integrated chlorophyll values greater than 300 mg/m-. Only the outer regions of the study area to the north and east had values less than 1 00 mg/m-. In the Chukchi, as with the Bering Sea components of the cruise, high chlorophyll values were observed off the Soviet coast at Stations 44. 59, 7 1 , and 72. The lowest values in the area, less than 50 mg/m-, were found closer to the Alaskan coast. Cross sections from Stations 72-75 and Stations 7 1-66 show high phytoplankton biomass on the western side of the basin, presumably as a result of the flow of Bering Shelf- Anadyr water carrying its load of phytoplankton and nutrients (Figs. 3b,c). Cross sections from Stations 59-65, and Stations 44-50, indicate that the characteristic water masses of this system are no longer recognizable from chlorophyll distribution measurements ( Figs. 3d,e). North ofapproximately 67° latitude, the Bering Shelf-Anadyr water masses appear to spread out as current speed decreases and the flow becomes bathymetrically steered (Coachman & Shigaev, Subchapter 2.1, this volume). High chlorophyll concentrations occurred all across the transect even close to the Ala.skan coast at Station 48 (Fig. 3e). High integrated chlorophyll (>,W0 mg/m- )ischaracteristic of Stations 54 and 64 near the eastern side of the study area ( Fig. I ). Cross sections from the northern Chukchi Sea (Figs. 3d,e) exhibit a pronounced subsurface chlorophyll maximum similar to those observed in the Chirikov basin and Benng Strait. Concentrations greater than 70.0 mg/m' were measured at 15 m at Station 54. b) Discussion and Conclusion Our data support the general model that the advection of the Anadyr water mass over the continental shelf of the northern Bering Sea and into the Chukchi Sea strongly influences the biological regune. In its wake (Coachman et al.. 1975) is left a bounty of biological production resulting from its nutrient load and the morphology of the shelf. Chlorophyll measurements from the Gulf of Anadyr 3) indicate a northward flow of nutrient-rich water around the gulfs perimeter, originating from the bifurcation of the Bering Slope Current in the vicinity of Cape Navarin. The influence of Anadyr water (created by slight modification of Bering Slope water in the Gulf of Anadyr) is not evident until it reaches the euphotic zone as it flows around the Gulf of Anadyr and through Anadyr Strait. The flrst biological indications of this water mass are present at shallow-water stations in the northwest ^'g -"* Gulf of Anadyr where the nutrient-rich water is exposed to the CL UJ Q STATIONS 44 45 46 47 48 49 50 0 65 130 195 260 59 60 61 62 63 64 65 0 60 150 230 310 71 70 69 68 67 66 0 10 20 30 40 50 60 0 50 100 150 200 72 73 74 75 #=-^ ( 3 1 \^ 4 ^^.-^ ^^^~~ i^- -"""^^ 1 1 1 0 25 50 75 100 130 76 77 78 ,— , n 79 80 81 0 25 50 DISTANCE (km) Vertical cross-sections of chlorophyll (mg/m') arranged from South to North (a to e). Transect location given on Frontispiece. 126 euphotic zone. High phytoplankton biomass at Stations 24 and 26 with lower biomass at surrounding stations indicate that there may be a more complex production system operating in the Gulf of Anadyr than our sampling regime was able to adequately evaluate. Chlorophyll data indicate that the tlow of Anadyr water as the Anadyr Stream is entrained along the Soviet coast as it flows north. High chlorophyll measurements consistently occur near the Soviet coastline in the northern Bering Sea. However, the influence of the Anadyr Stream on phytoplankton biomass further from the coast was evident in a large loop of chlorophyll isoplelhs in the central Chirikov basin (Fig. 1). This pattern of phytoplankton distribution could result from the flow of Anadyr water through the western end of Shpanberg Strait into Chirikov basin or it could result from eastward advection of high nutrient water flowing through Anadyr Strait. Analysis of cross-sections from Chirikov basin indicate that the loop of phytoplankton biomass, shown as a distinct subsurface chlorophyll maximum, may be a separate entity from the phytoplankton stock closer to the Soviet coast ( Fig. 2d ). Both phytoplankton concentrations merge as Anadyr and Bering Shelf waters merge and flow through the western side of Bering Strait. The highest phytoplankton biomass in the Chirikov basin can be found near the Soviet coast. Future expeditions should examine the Soviet coastal areas more intensely. Water masses in the Chirikov basin (Anadyr, Bering Shelf, and Alaska Coastal) appeared well-defined with respect to phytoplankton biomass distribution. An explanation for the "loop" of phytoplankton in the central Chirikov basin is difficult from chlorophyll data alone. The flow of Anadyr and Bering Shelf water into the Chukchi Sea carries not only nutrients but phytoplankton from the productive regions upstream in the Chirikov basin. As opposed to the areas south of Bering Strait, identification of individual water masses by chlorophyll distribution is difficult. The absence of high chlorophyll values near the Alaskan coast reflects the passage of nutrient-poor Alaska Coastal water. The high nutrient Anadyr and Bering Shelf water masses and their associated phytoplankton stocks mix in Bering Strait and flow into the Chukchi Sea creating the large chlorophyll pool in the center of the basin (Fig. I ). Chlorophyll distribution in the Chukchi Sea supports the presence of a southeast flowing current, from the north on the Soviet coast (Zenkevitch, 1963; Coachman & Shigaev, Subchapter 2.1, this volume). Areal distribution and depth- sections of data indicate that the high chlorophyll values found in this region have a distinct source near the Soviet coast (Figs. l,3c-e). Depth-sections from the northernmost (Stations 59-65 and 44-50) transects suggest the existence of two separate chlorophyll stocks, one over Hope Sea Valley in the central Chukchi basin and one along the Soviet coast northeast of Kolyuchin Bay (Figs. 3d,e). Data from the southernmost transects in the Chukchi Sea, below 67° latitude, do not clearly show these stocks (Fig. 3b). It is difficult to distinguish the potential influence of high nutrient Siberian Coastal water from that of Anadyr Stream flowing north through Bering Strait. The data from the Akculewik Korolev expedition fill several gaps in the growing data base for the Bering/Chukchi Seas. Since 1983, the ISHTAR Project has studied the ecology of the northern Bering and southern Chukchi Shelf. But it was not until the results of the expedition aboard XheAkadeinik Korolev that hypotheses concerning the functioning of this productive marine ecosystem could be confirmed (see Walsh et ciL, 1 989). This project was part of the Third Joint US-USSR Bering & Chukchi Seas Expedition aboard the Soviet research vessel Akademik Korolev. We express appreciation to the US Fish and Wildlife Service and the USSR State Committee for Hydrometeorology . who made our participation possible. Our participation was funded in part by the National Science Foundation. Grant DPP-8405286. Contribution No. 627. Institute of Marine Science. University of Alaska. Fairbanks, AK 99775-1080, USA. 5.1.3 Distributions of Algal Pigments in Near- surface Waters ROBERT R. BIDIGARE, MICHAEL E. ONDRUSEK, and JAMES M. BROOKS Geochemicul and Environmental Research Group. Departmenl of Oceanography. Te.xas A&M Universitx. College Station. Texas. USA Introduction The Bering Sea is a productive, high-latitude oceanic environment whose expanse shelf supports large standing stocks of zooplankton and marine vertebrates. In contrast to most oceanic regions, the Bering Sea has high levels of phytoplankton biomass and production associated with waters overlying its shelf domain, as well as its open-ocean domain (Holmes, 1958; Kawamura, 1963; Taniguchi, 1969; McRoy etai, 1972; Koike ('/«/., 1982; Sambrotto <>/«/., 1984, 1986; Hansen et al., 1989). Wal.sh et al. (1985) proposed that a significant proportion of the shelf-based production is transported to the Bering Sea Slope, which serves as a major storage site for atmospheric carbon dioxide. The fact that the 127 zooplankton-to-phy toplankton biomass ratio calculated for the Bering Sea is higher than most oceanic areas (Motoda & Minoda, 1974) suggests that there is an efficient transfer of phytoplankton carbon to higher trophic levels. However, recent work by Springer et cil. ( 1 989 ) indicates that on average the zooplankton of the northern Bering Sea are unable to control the large blooms of diatoms that occur during springtime in this region. Sambrotto etal. ( 1 986 ) have shown that there is a significant degree of seasonal variability in both phytoplankton biomass and production on the southeastern Bering Sea Shelf. The shallowing of the mixed layer was the most important process responsible for bloom initiation, which occurs annually during early May. The investigators also concluded that vertical mixing forced by atmospheric events is important in controlling the magnitude of the spring bloom. Innerannual variations in zooplankton biomass have also been documented for the Bering Sea, which may reflect variations in meteorological conditions (Motoda & Minoda, 1974). During early to midsummer, boreal-oceanic diatoms dominate the phytoplankton community of the open western/central Bering Sea and the eastern Bering Sea Shelf, while temperate-neritic diatoms are characteristically found in the vicinity of the Aleutian Island chain (Motoda & Minoda. 1974: Whitledgeeffl/., 1988). The dominant offshore diatoms include representatives from the following genera: Chaetoceros sp., Rhizosolenia sp., Denticula sp., Thalassiosira sp., Nilzschia sp., Fragilaria sp., and Thalassiothrix sp. On the southeastern Bering Sea Shelf, diatoms are dominated by Thalassiosira aestivalis and T. nordenskioldii during prebloom conditions (April) and Chaetoceros spp. (especially C. debilis) during bloom conditions that occur during May (Sambrotto et al.. 1986). Kisselev (1937) also reported the presence of dinoflagellates and green algae in the northern Bering Sea. ' To further investigate the distributions of phytoplankton in the Bering and Chuckchi Seas, near-surface water samples were analyzed for pigment content by high-performance liquid chromatography (HPLC). This study was part of the Third Joint US-USSR Bering & Chukchi Seas Expedition, designed to examine biological-chemical-physical interactions in the Bering Sea. Materials and Methods A series of stations were occupied during July-August 1988 aboard the R/V Akademik Korolev in the Bering and Chukchi Seas. Near-surface samples were collected at 1 12 of these stations for the determination of photosynthetic pigment concentrations (Figs. 1-12). One-liler water samples were filtered through 47 mm GF/F glass fiber filters and transported to Texas A&M University for HPLC pigment analysis. Filters were extracted in 6 ml lOO'/f acetone (final acetone concentration - -90%) for 24-48 h (-20 "C). Following extraction, pigment samples were centrifuged for 5 min to remove cellular debris. Pigment extracts were analyzed for pigment content by HPLC (Bidigare, 1989). Briefly, chlorophylls and carotenoids were separated using a Spectra-Physics Model SP8700 liquid chromatograph equipped with a Radial-PAK C.s column (0.8 X 10 cm, 5 |i particle size; Waters Chrom. Div.) at a flow rate of 6 ml/min '. Prior to injection, 1 ml aliquots of the standards and algal extracts were mixed separately with 300 |i 1 of ion pairing solution (Mantoura& Llewellyn, 1983). A two-step solvent program was used to separate the algal pigments. After injection (500 \i\ sample), mobile phase A (80: 1 5:5; methanol:water:ion-pairing solution) was ramped to mobile phase B (methanol) over a 12-min period. Mobile phase B was then pumped for 18 min for a total analysis time of 30 min. Individual peaks were detected and quantified (by area) with a Waters Model 440 Fixed Wavelength Detector (436 nm) and a Spectra-Physics Model SP4400 integrator, respectively. The identities of the peaks were determined by comparing their retention times with those of pure standards and extracts prepared from "standard" plant materials of known pigment composition. On-line diode array spectroscopy (HPLC/DAS; 350-550 nm for carotenoids and 400-700 nm for chlorophylls) using a Hewlett-Packard Model HP8451 Diode Array Spectrophotometer was performed to confirm the identities of the major chlorophylls and carotenoids. The HPLC system was calibrated with pure standards whose concentrations were determined spectrophotometrically in 1-cm cuvettes (Bidigare, 1989). Known pigment quantities were injected and resultant peak areas were used to calculate individual standard response factors (ng area'). Pigment concentrations (ng pigment 1 ' ) of the samples were calculated with these response factors and knowledge of the extraction and sample volumes. The HPLC method employed is not capable of separating chlorophyll c, from chlorophyll r,, nor zeaxanthin from lutein. Results The quantitatively important algal pigments measured in suspended particulate samples collected from near-surface waters of the Bering and Chukchi Seas were chlorophyll a; chlorophyllide a; chlorophyll b\ chlorophylls c, -i- c,; chlorophyll c,; 19'-hexanoyloxyfucoxanthin: 19- butanoyloxyfucoxanthin; fucoxanthin; peridinin; diadinoxanthin; diatoxanthin: and p,p-carotene (Table 2). Concentrations of zeaxanthin plus lutein, prasinoxanthin, and alloxanthin were near or below the limit of HPLC quantification. Phytoplankton pigments in the study area were not uniformly distributed. Chlorophyll a concentrations ranged from 1 2 to 26,6 1 8 ng 1 ' , wi th highest concentrations measured in the Gulf of Anadyr and the Chukchi Sea (Fig. 1). Distributions of chlorophyllide a, chlorophyll c, fucoxanthin, diadinoxanthin, diatoxanthin, and |3,P-carotene all displayed patterns similar to that of chlorophyll rt (Figs. 2,4,7,10,1 1,12). In contrast, elevated concentrations of chlorophyll /' and peridinin were measured in a narrow zone extending from the Chirikov basin to just north of the Bering Strait (Figs. 3,6). Chlorophyll c„ 19'-hexanoyloxyfucoxanthin.and 1 9 -butanoyloxyfucoxanthin 128 levels were highest at stations occupied in the Chirikov basin and the south-central Bering Sea (Figs. 5,8,9). A tabular listing of stations, positions, and algal pigment concentrations is given in the Table 1. Discussion The concentrations of photosynthetic pigments in the marine environment are primarily dependent on the quantity, species composition, and photoadaptative state of the phytoplankton present. For these reasons, accessory chlorophyll and carotenoid pigments have been used as diagnostic "tags" for investigating algal distributions and their physiological processes. In coastal waters off Australia, Jeffrey (1974) documented the usefulness of acces.sory pigments for examining phytoplankton distributions in the water column. The thin- layer chromatographic method employed identified the major pigments as chlorophylls a. h, and c: carotene; astaxanthin; fucoxanthin; peridinin; diadinoxanthin; and neoxanthin. Chromatographic data were used to "fingerprint" vertical and temporal variations in the phytoplankton community structure. Several recent investigations have demonstrated the utility of HPLC as a "chemotaxonomical" tool for identifying marine algal groups. For example, high concentrations of zeaxanthin were used to infer the presence of cyanobacteria in the North Sea and tropical Atlantic Ocean (Gieskes& Kraay, 1983a). In another study, the dominance of a symbiotic cryptomonad was established for a spring bloom in the central North Sea by HPLC identification ofalloxanthin, a carotenoid characteristic of this marine algal group (Gieskes & Kraay, 1983b). HPLC pigment analysis has also been shown to be useful for characterizing phytoplankton biomass and compositional changes across frontal systems located at the northern wall of the Gulf Stream (Amone et ai, 1986; Trees el al, 1986) and in the Santa Barbara Channel (Smith et al, 1987). In this study, the criteria presented in Table 3 were used to infer distributions for the major algal groups (diatoms, green algae, dinoflagellates, chrysophytes, and prymnesiophytes). The most abundant accessory pigments detected in this study were chlorophyll c, diadinoxanthin, and fucoxanthin (Table 2), which reflect the dominance of diatoms in the Gulf of Anadyr and the Chukchi Sea during midsummer. In addition, the suite of pigments also common to the diatoms (chlorophyllide «, diatoxanthin, and p,P-carotene) all displayed elevated concentrations in these regions. Distributions of chlorophyll b and peridinin indicate that green algae and dinofiagellate abundances were highest in a band extending from just north of St. Lawrence Island, through the Bering Strait, and into the Chukchi Sea. These distributional patterns are consistent with those described by Kisselev ( 1937 ), who found that these algal groups were abundant in the northern Bering Sea. 1 9'-Hexanoyloxyfucoxanthin and 1 9'-butanoyloxyfucoxanthin concentrations were highest in waters overlying the Chirikov basin (located just north of St. Lawrence Island)and the central and southern regions of the Bering Sea, reflecting the presence of prymnesiophytes and chrysophytes, respectively; concentrations of these pigments were near the limit of HPLC detection at stations occupied in the Chukchi Sea. In summary, pigment concentrations in the Bering and Chukchi Seas were complex and variable and suggest that phytoplankton are not uniformly distributed with respect to both biomass and composition. A comparison of these distribution patterns with concurrently measured physico- chemical parameters (i.e., nutrients and currents) will provide insight into the factors affecting phytoplankton abundance in the Bering and Chukchi Seas. Fig. 1 . Contours of chlorophyll (J ( ng'l ' ) measured in Ihe Bering and Chukchi Seas during July-August 1988, aboard the R/V Akculemik Korulev. Fig. 2. Contours of chlorophyllide a (ng-1 ') measured in the Bering and Chukchi Seas during July-August 1988. aboard the RA' Akademik Korolev. 129 Fig. 3. Contours of chlorophyll /)(ng'l ') measured in the Bering and Chukchi Fig, 4. ContoursolchlorophyllttngM 'Jmeasuredinthe BeringandChukchi Seas during July-August 1988, aboard the RA' Akademik Korolev. Seas during July-August 1988, aboard the IW Akademik Korolev. Fig. 5. Contours of chlorophyll c, (ng-1') measured m the Bermg and Fig. 6. Contours of pendmm (ng'l ') measured in the Bering and Chukchi Chukchi Sea.s during July-August 1988, aboard the RA' Akademik Seas during July-August 1988, aboard the R/V Akademik Korolev. Korolev. 130 Fig. 7. Contoursoffucoxanthin ( ng'l') measured in the Benng and Chukchi Seas during July-August 1988, aboard the RA" Akademik Korolev. Fig. 8. Contours of 1 9'-butanoloxyfucoxanthin (ng'l ' ) measured in the Bering and Chukchi Seas during July-August 1 988, aboard the KN Akademik Korolev. Fig. 9. Contours of 19'-hexanoyloxyfucoxanthin (ng'l') measured in the Fig. 10. Contours of diadinoxanthin (ng-1 ') measured in the Bering and Bering and Chukchi Seas during July-August 1988, aboard the IW Chukchi Seas during July-August 1988, aboard the RA' Akademik Akademik Korolev. Korolev. 131 Fig. 1 1. Contoursofdiatoxanthin(ng»r') measured in the Bering and Chukchi Fig. 12. Contoursofp.p-carotene(ng»l"')measured in the Beringand Chukchi Seas during July-August 1988, aboard the R/V Akademik Korolev. Seas during July-August 1988, aboard the RA' Akcidemik Korolev. TABLE 1 Near-surface pigment concentrations (ng 1 ') measured in the Bering and Chukchi Seas during July-August 1988. Station Lat(N) Lon(W) Chlr, Chida Chk Per Bfuc Fuco Hfuco Diad Diat Chi/; Ch\a Car AKA-I .S7..'S4 174.48 35 42 125 95 35 272 140 60 13 120 717 0 AKA-2 57.50 175.52 26 116 183 66 51 733 181 63 0 112 869 0 AKA-3 57.93 175.08 45 44 186 116 60 476 218 115 9 153 1061 0 AKA-4 58.52 174.49 46 54 171 46 65 466 181 107 29 62 878 0 AKA-5 58.50 175.50 0 0 0 0 0 44 T) 14 0 0 194 0 AKA-6 59.50 179.50 0 0 38 20 37 235 124 33 0 74 658 0 AKA-7 60.47 177.83 0 0 46 0 14 57 105 6 0 0 228 0 AKA-8 60.94 176.93 0 0 0 0 8 17 29 0 0 0 175 0 AKA-9 61.34 176.10 0 0 0 0 35 40 9 7 0 0 TTT 0 AKA-10 61.25 176.76 0 0 42 0 42 70 151 43 9 0 351 0 AKA-ll 61.58 178.65 2 76 71 0 21 51 130 42 0 0 280 0 AKA-12 61.88 179.42 0 0 0 .0 16 27 41 14 0 0 208 0 AKA-13 62.18 179.85 0 0 0 0 14 47 44 14 0 0 203 0 AKA-14 62.84 179.51 0 0 13 0 1 24 ->-) 10 0 1 292 0 AKA-15 62.58 178.51 0 0 0 0 0 6 10 0 0 0 66 0 AKA-16 62.34 177.33 0 0 0 0 0 24 16 0 0 0 172 0 AKA-17 62.17 176.34 0 0 0 0 12 39 44 23 0 0 190 0 AKA-18 62.01 175.04 0 0 0 0 7 21 7 1 0 14 150 0 AKA-19 62.44 174.01 0 0 0 0 17 17 9 9 0 0 142 0 AKA-20 62.58 175.06 0 0 0 0 24 24 24 13 0 68 195 0 AKA-2 1 62.75 176.17 0 0 0 0 0 44 10 18 0 0 148 0 AKA-22 63.00 177.03 (J 0 0 0 0 0 10 0 0 0 81 0 AKA-23 63.35 177.84 0 0 0 0 3 TT 12 12 0 0 162 0 132 TABLE 1 - continued Station Lat(N) Lon(W) Chlr, Chida Chl( Per Bfuc Fuco Hfuco Diad Diat Chi/; Chla Car AKA-24 63.68 178.47 0 186 4,290 0 0 11,666 0 1,074 155 203 26.618 318 AKA-25 64.00 179.33 0 0 0 0 0 55 0 19 0 0 215 0 AKA-26 65.00 178.67 0 0 0 0 0 35 0 4 0 0 89 0 AKA-27 64.74 177.78 0 0 43 0 12 225 42 50 0 0 760 0 AKA-28 64.25 177.50 0 0 61 0 11 278 13 45 0 0 692 0 AKA-29 63.83 176.97 0 0 0 0 2 7 13 4 0 16 99 0 AKA-30 64.17 175.97 0 0 0 0 21 30 44 10 0 0 122 0 AKA-31 64.34 175.01 0 0 15 86 12 155 33 90 0 53 645 0 AKA-32 64.00 180.00 0 0 0 0 26 14 38 13 0 8 143 0 AKA-33 63.49 175.03 0 0 0 0 0 0 10 1 0 0 61 0 AKA-34 63.18 174.14 0 0 0 0 0 0 18 0 0 0 84 0 AKA-35 63.02 173.00 0 0 0 0 0 0 44 5 0 0 119 0 AKA-36 63.45 172.18 0 0 0 0 15 21 13 11 3 34 98 0 AKA-37 63.66 173.82 0 0 0 0 0 6 12 0 0 0 75 0 AKA-38 63.90 173.53 0 0 0 0 0 28 21 17 0 52 392 0 AKA-39 64.23 172.70 0 51 381 0 0 997 0 109 0 0 3,227 0 AKA-40 64.13 172.50 0 37 151 0 0 371 0 69 16 0 697 0 AKA-41 64.03 172.21 0 6 65 0 0 213 0 52 0 0 285 0 AKA-42 63.92 172.07 0 0 0 0 12 38 17 17 0 43 221 0 AKA-43 64.10 171.20 0 0 0 0 9 14 9 14 0 0 164 0 AKA-44 67.37 173.33 0 0 15 0 0 61 0 11 0 0 102 0 AKA-45 67.74 172.80 0 0 0 0 0 39 0 9 0 0 163 0 AKA-46 67.92 171.75 0 0 0 0 0 18 0 8 0 0 104 0 AKA-47 68.10 170.88 0 0 0 0 0 68 0 28 0 0 133 0 AKA-48 68.27 170.00 0 0 21 0 0 158 0 33 0 0 368 0 AKA-49 68.47 169.13 0 0 3 0 0 49 0 5 0 0 250 0 AKA-50 68.66 168.33 0 0 0 0 0 57 9 3 0 113 332 0 AKA-51 68.16 168.74 0 0 0 0 0 75 0 15 0 0 137 0 AKA-52 68.08 167.00 0 0 31 0 0 71 0 6 0 0 266 0 AKA-53 67.70 165.72 0 0 13 0 0 83 0 4 0 67 539 0 AKA-54 67.76 167.32 0 0 69 0 0 419 0 44 0 0 952 0 AKA-55 67.74 168.44 0 193 1,894 0 0 6,723 0 468 45 75 13,198 170 AKA-56 67.74 169.93 0 0 0 0 0 4 0 0 0 0 12 0 AKA-57 67.71 171.35 0 0 0 0 0 78 0 29 0 0 154 0 AKA-58 67.50 172.14 0 0 0 0 0 77 0 26 0 0 165 0 AKA-59 67.15 171.99 0 0 0 0 0 47 0 6 0 0 154 0 AKA-60 67.26 170.83 0 0 13 0 0 89 0 20 0 0 265 0 AKA-61 67.33 169.75 0 17 123 0 0 426 0 44 0 0 938 0 AKA-62 67.34 168.72 0 41 449 32 0 1,361 0 108 13 62 3,265 36 AKA-63 67.34 167.73 0 93 355 0 0 1,517 0 101 0 0 3,135 0 AKA-64 67.30 166.71 0 4 119 0 0 540 0 41 0 0 1,199 0 AKA-65 67.34 164.98 0 0 39 49 0 91 37 17 0 137 485 0 AKA-66 66.93 165.92 0 0 40 0 0 290 0 17 0 0 512 0 AKA-67 66.93 165.83 0 0 0 (1 0 89 0 18 0 0 324 0 AKA-68 66.92 167.83 0 19 102 0 0 475 0 45 0 0 834 0 AKA-69 66.91 168.91 0 8 284 0 0 1,283 0 118 23 0 3147 5 AKA-70 66.91 169.92 0 194 1,329 0 0 4,846 0 257 20 133 10,426 180 AKA-71 66.91 171.01 0 0 9 0 0 118 0 21 0 0 275 0 AKA-72 66.55 170.17 0 11 401 0 0 1,801 0 179 7 0 4,098 21 AKA-73 66.55 169.32 16 84 273 0 0 1,090 6 98 31 119 2,488 12 AKA-74 66.56 168.60 0 38 131 52 0 677 0 67 22 162 1,559 0 AKA-75 66.55 167.29 0 0 20 0 0 242 0 24 0 0 742 0 AKA-76 65.98 169.60 0 184 1,607 0 16 4,521 0 344 28 77 10,713 119 AKA-77 65.93 169.35 0 0 91 0 10 338 8 58 14 67 981 0 AKA-78 65.85 169.22 0 140 422 0 0 1,110 0 80 0 0 2.765 0 AKA-79 65.70 168.68 0 0 55 0 0 399 12 40 0 0 742 0 AKA-80 65.67 168.50 0 0 6 0 0 257 0 7 0 0 485 0 AKA-81 65.63 168.35 0 0 14 0 7 271 0 16 0 0 539 0 AKA-83 65.67 168.50 73 182 196 29 0 341 11 29 0 370 1,039 0 AKA-84 65.71 168.69 0 0 63 95 19 354 48 42 0 190 1,215 0 133 TABLE 1 - continued Station Lat(N) Lon(W) Chic, Chida Chk Per Bfuc Fuco Hfuco Diad Diat Ch\b Ch\a Car AKA-85 65.83 169.17 16 104 288 27 19 887 25 98 23 181 2,357 27 AKA-86 65.94 169.38 27 31 326 0 0 1,577 0 131 21 0 3,835 24 AKA-87 65.41 170.36 41 163 955 0 21 3,231 0 243 31 0 7.813 155 AKA-88 65.36 169.99 0 18 194 58 0 907 0 79 0 65 1.889 14 AKA-89 65.24 169.36 0 47 171 0 0 586 0 53 0 0 825 0 AKA-90 65.18 168.66 0 24 144 54 0 479 15 83 12 53 962 0 AKA-91 65.24 167.98 0 30 64 38 0 360 5 44 0 34 691 0 AKA-92 64.67 167.69 0 0 1 16 0 124 0 27 0 0 329 0 AKA-93 64.75 168.43 0 0 0 0 0 125 0 29 0 0 185 0 AKA-94 64.86 169.19 0 370 794 0 0 906 0 93 0 0 1.729 0 AKA-95 64.97 169.98 0 15 107 19 0 470 0 70 0 0 1.091 0 AKA-96 65.09 170.71 1-> 32 369 0 0 1.301 0 136 23 43 2,851 65 AKA-97 64.75 171.50 0 0 70 0 0 445 21 68 8 0 944 0 AKA-98 64.72 170.87 0 0 13 25 17 175 15 45 0 62 488 0 AKA-99 64.54 1 70.04 0 0 12 32 39 158 16 54 0 0 426 0 AKA-100 64.38 169.16 0 T) 93 0 0 320 0 42 0 0 421 0 AKA-101 64.23 168.32 0 0 40 0 0 213 0 55 0 0 311 0 AKA-102 64.09 167.39 0 0 21 0 0 273 0 42 0 15 226 0 AKA-103 63.66 168.36 0 0 0 0 0 144 0 39 0 0 251 0 AKA-104 63.85 169.21 0 21 211 0 65 836 0 165 0 0 773 9 AKA-105 64.03 170.09 T 0 112 38 239 583 83 197 7 77 1,315 3 AKA-106 64.22 170.98 1 0 67 0 114 246 122 112 6 127 874 0 AKA-107 64.40 171.62 0 0 36 0 0 295 0 14 0 0 476 0 AKA-108 54.42 176.74 0 0 26 0 66 126 104 59 0 0 483 0 AKA-109 54.5 1 175.47 0 0 15 0 63 118 104 46 0 10 412 0 AKA-110 53.93 176.01 64 75 114 0 40 267 199 147 14 0 369 0 AKA-111 53.53 175.54 0 0 54 16 61 120 133 85 14 47 396 0 AKA-112 53.43 1 76.59 99 129 234 30 72 623 308 124 0 75 801 0 AKA-113 53.17 177.22 0 0 103 30 47 108 214 45 0 111 533 0 TABLE 2 Average and range of photosynthetic pigment concentrations (ng 1 ' ) measured in near-surface waters of the Bering and Chukchi Seas durins Julv-Aucust 1988 (n = 112). Parameter Chic, Chida Chli Per BFuco Fuco HFuco Diad Diat Chi/) Chl(/ Car Average 5 26 167 10 13 567 30 64 5 31 1,301 10 Minimum ND* ND ND ND ND ND ND ND ND ND 12 ND Maximum 99 370 4.290 116 239 11,666 .308 1.074 155 370 26.618 318 *ND = not detectable 1.34 Pigment TABLE 3 List of the important phytoplankton pigments used as diagnostic source marlcers for interpretation of HPLC-derived pigment data. Significance Golden-brown Algae Fucoxanthm Chlorophyll c.+c. 19'-Hexanoyloxy fucoxanthm Fucuxanthin Chlorophyll r,+f, 19'-Butanoyloxyfucoxanthin Fucoxanthin Chlorophyll c,+Cj Peridmin Chlorophyll c. Chlorophyll b-containing Algae Lutem Prasinoxanthin Zeaxanthin Divinyl chlorophyll a Phycobilin-containing Algae Zeaxanthin Alloxanthin *Also contam minor amounts of zeaxanthin. Diatoms (and some Chrysophytes and Prymnesiophytes Prymnesiophytes Chrysophytes Dinoflagellates Chlorophytes* Prasinophytes* Prochlorophytes Coccoid Cyanobacteria Cryptophytes 5.1.4 Complex Hydrooptic Researches ALEXANDER A. KUMEISHA' . SERGEI N. DRAKOV, and ALEXANDER E. LUKIN' 'Institute of Physics and Academy of Sciences. Minsk. BSSR * Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR Introduction In the ocean ecological researches of today, the optical methods find practical application alongside of traditional biochemical methods. These new methods have undoubtedly some advantages over the conventional ones. It is possible to make measurements without disturbing the environment; there is high spatial and time resolution and wide diversification of the information received. The interaction of biological and hy drophy sical factors gives rise to the formation of conservative optical structures, dependent primarily on phytoplankton and their metabolites. As waters are carried by currents from regions of formation, the biocenoses living therein undergo gradual transformation, which is reflected in the optical properties. Thus, if we identify those optical features that are typical of water masses of different origin (or characteristic of water mass in one or another stage of transformation), we shall be able to identify ocean waters in terms of productivity and other biological properties. The properties of light scattering are dependent upon phytoplankton, which are extremely susceptible to pollution. By determining the deviation of water optical properties from natural level (in the regions that 135 potentially can be affected anthropogenically), we can draw conclusions about the extent of pollution and to monitor its dynamics. The paper presents the results of complex hydrooptical studies in the waters of the Bering and Chukchi Seas, The main objective pursued was to study spatial and time variability of hydrooptical characteristics and their correlation with biological and microphysical parameters of particulates. Hydrooptical Quantities — Definitions Distribution of light in the ocean water is a function of its absorption and scattering. These phenomena can (neglecting polarization) be fully described by three primary hydrooptical quantities; 1. indices of absorption k; 2. scattering cr, and 3. the angular dependence of scattering, x(Y) indicatrix. If a collimated monochromatic beam of light is incident along an axis (1) traveling through a small volume dV=dSdl in the medium, this beam passes in solid angle, dw and creates illumination E„(dS ) on an area normal to the beam. The amount of flux absorbed by the volume will be proportional to dF=KE„dSdl (1) Proportionally factor k is known as the coefficient of absorption, its dimension is M ' ". The scattering index cr. dF =aE„dSdl . (2) so that the full value of flux, scattered and absorbed on its path dl, will equal equations ( 1 ) and (2): dF=dF,+dF =(K+o)E„dSdl^E„dSdl . (3) The sum of absorption k and scattering o indices is known as attenuation index 8 , and the relationship A=5/e is the probability 01 photon survival. The dimension of attenuation index is e[M ']. T=e' defines the transmissivity of a water layer 1-m thick, also referred to as transparency of water. Expression (3) is a differential fonn of Bouguer's Law, according to which any flux that has travelled in a scattering and absorbing medium, is attenuated (hereinafter we shall consider the values of relevant indices determined to the In base): F(l)=F(o)exp(£l). (4) Scattering of light varies with direction. A flux of light, scattered in a single solid angle (or intensity of light dl) in a direction, making up angle y with axis 1, will be proportional to the value of volume dV of flux; dI(Y)-C(Y)E„dV. (5) Proportionality factor cs(y ) is ternied as the index of directed scattering and has the direction [ M ' ster ' ] ■ Scattered ( radiation diffused) is known as the indicatrix of scattering: X(Y)= 0(Y) ■ <6) o SinceJ /(y) dw= I, it can be treated as three-dimensional density of probability of photon scattering at some angle (y ) with respect to the direction of light propagation. Often used in hydrooptics are the so-called integral quantities — indices of scattering in front (6) and back ((i) hemispheres: 5=27tl C3(7)sinYdY, P = 2rtj cXyJsiuYdY kI2 (7) (8) and their ratio K=5/p, called the asymmetry factor. The extent of isotropy of scattering is defined by the mean cosine of scattering: c5sY = 2jrI x(Y)sinYCOSYdY (9) Parameters K and cosy characterize indicatrix "stretching," which increases with the increase of particle sizes. The anisotropy of scattering will also be characterized by R(YJ = 27i1 x(Y)sin(Y)dY. (10) determining a part of radiation scattered into solid angle with angular opening from 0 to y,,- Let us take 2° for Yo- Hydrooptic Instruments Critical for making complex hydrooptical measurements //( situ is their synchronism. The apparatus complex, used by us, made it possible to realize this principle with the help of rather simple technical means. The complex included an immersible transmittance meter with a bathometer and a board meter of angular light scattering indicatrix-meter. First, a vertical profile attenuation index e of water was measured, and second, the angular characteristics of light scattering (C5( y ) ) of samples were taken from different horizons. The photometer/transmittance meter used was a '■Kvant-3." The optical-mechanical and electronic units of the instrument are accommodated inside a hermetic case, which, via traction and electric connectors, is connected with a double cable-line, type KF 7-90-180. The meter measures and compares the intensity of light flux before and after its passing through a layer of certain thicknesses 1 ( defined by the instrument measurement base). This principle of measurement is realized as follows: formed by corresponding elements of the optical- mechanical unit, a probing beam of light is emitted through a 136 porthole into the seawater; then, after having been reflected from an outboard spherical mirror, it returns. Such a returning beam, attenuated by the seawater, is directed to a photomultiplier where it is compared with a reference beam, passing inside the instrument. Originally, this reference beam has the intensity equal to that of the probing beam. The required spectral range is discriminated with the aid of a suitable light filter, which is installed in front of the photomultiplier. A different signal is transmitted over the cable-line to the board block and registered there as a function of the depth probed. The instrument measurement base is 0.5 m; maximum depth of immersion, 250 ni (Kumeisha & Vinokurov, 1984). The assessment of measurement errors is a very difficult problem because of the lack of "clear water" reference. Usually verification is carried out with the aid of samples that are standardized neutral filters and thin glasses and whose coefficients of transmissivity (orrellection) are measured on a standard spectrophotometric equipment or can readily be calculated. Modeling has shown that the absolute error of measurements made to detemiine the attenuation index of clear {£ < 0.15 m ') waters is not in excess of 0.01%; in less clear waters the relative error is nearly 5%. A bathometer is an attachment to the "Kvant-3"" transmittance meter which allows an assessment, on the basis of visual analysis, of a profile of the attenuation index. The bathometer valves are tested for reliable functioning by measuring the transmittance of an assay selected, making use of a special cell in the "Kvant-3" instrument (intended for onboard analysis), and then comparing transmittance values with those measured //( situ on the horizons of probing. All tests showed satisfactory results. A board indicatrix meter is constructed as a cylindrical cell with an attached illuminator and scanning device with a photodetector. The illuminator emits a collimated beam of light, which, via portholes in the cell, transilluminates water samples (cell volume is 3 ml). The scanning device receives radiation scattered from the zone at angles from 0.5° to 165° relative to the direction of its propagation. The illuminator and receiver embody aperture and field diaphragms pemiitting alteration of angular divergence of light fiuxes and their cross- sections. The volume, subjected to photometry analysis, is 5- 10 ml. Hence, one can safely neglect the contribution of this factor to the scattering of zooplankton. Received light is directed to the photomultiplier through a glass light filter; an electric signal, proportional to the light flux, is then amplified, filtered, and applied to a digital recorder. In order to obtain absolute values of scattering indices, the intensity of light that has passed through the instrument is measured (Gabrilovich, 1976). The instrument was verified with the aid of monodisperse polystyrene latex solution. Comparing the results of measurements and calculations, the relative error of angular measurements of light scattering has been found to be 10%. Results All primary hydrooptic characteristics were measured at wavelength X = 530 mm. The obtained vertical profiles of attenuation index were tabulated through 1 m in shallow parts of the seas and through 5 m at depth H = 100-250 m. Since, in biology, they often operate with average characteristics ( related to water layer or water column), we also calculated average index of attenuation in layer 0-H: j e(H')dH' H = H Absolute values o{y) within 0.5-165°, full index of scattering and integral characteristics of indices (k, cos y and R [ Y„ = 2° 1 ) were calculated from angular relationships of light scattering. Volume concentrations V^ and V, (in cmVm') of coarse (particles having radii in excess of 1 urn) biological and fine mineral (less than 1 |im) fractions of suspended matter were assessed following Kopelevich (1981). Such calculations are possible using a physical model of scattering. Ocean water particulates is divided into two independent fractions in terms of size and index of refraction. Angles of y < 2° for coarse particles, and y> 45° for fine, can be calculated; however, the numbers are weakly correlated. This is, of course, an idealized model of ocean water particulates; yet, on the whole, it allows interpretation of material that has been collected earlier. Its advantage lies in the fact that it permits assessing the content of fine fraction particulates (including submicron particles), which is beyond the capacities of conventional geological methods. It should be noted, however, that the model has not been tried by the author ( Kopelevich, 1 98 1 ) to describe indicatrices of highly productive waters where variation of content of coarse and fine particulates differs from that in open ocean. Fine suspended particles may predominantly be of organic matter. Applicability of generally accepted concepts becomes doubtful when suspended minerals dominate in coarse fraction. This is why the assessments of particulates content, presented in this report, should be regarded only as preliminary, subject to verification through direct biological observations and through appropriate model-based calculations. Volume content of fine and coarse fractions (V, and VJ was inferred from the following relations: V, = 10.2o,4, ,-1-4x1 0-*o,,., -0.002, V, = 2.2xl0^o„.,-1.2a,45.„ (11) (12) where o,, ,and 0,43, are indices ofdirected scattering at l°and 45° angles. The optical type of water, assessed from measured values of 0,4;; I and o, , ,, will also be helpful when added to the above- mentioned parameters. Since according to ( 1 1 ) and (12) such 137 values show the content of fine and coarse fractions in particulates, the typification will differentiate waters by their contents of possible volumes of coarse and fine particles. High concentration of a certain fraction will be denoted by the letter "H,"" medium by "M,"" low by "L." Combinations of these will be denoted by two-letter codes, of which the first letter specifies volumetric content of fine particles and the second letter that of coarse particles. The numerical equivalent of the letters used has been given in Table 1 . This typification is very helpful. Comparisons of waters in the areas explored by us with typical ocean waters in different stages of development can be made quickly. For instance, from data of the same paper, type MM is typical of open ocean waters; types LM (particularly, LL and ML) are typical of deep-water horizons and types MH, HM, and HH only of higher productivity regions. Fraction TABLE 1 Volumetric content. cmVm' L M H Coarse Fine <0.1 <0.015 0. 1 -0.45 0.015-0.055 >0.45 >0.055 Chukchi Sea Investigation of Spatial-Temporal Variability of Transmittance Field Fig. I, Zonal dislnhution of attenuation index {£ ) average for a certain layer of water. It would probably be most reasonable to begin analyzing the hydrooptic characteristics of spatial-temporal variability by considering zonal distribution transmittance in northern waters. The frontispiece shows that route of expedition with numbers of stations. Numeration relates to the period of joint Soviet-American research. Water transmittance T is dependent upon the attenuation index (e ) according to the relation T = e*. In the literature, data is presented for the attenuation index field. In order to make it possible to compare our results with the data of other researchers, we shall keep to this tradition (i.e., we shall imply, when speaking of "transmittance" and "transmittance field," corresponding values of distribution e) . Figure 1 shows zonal distribution of attenuation index ( e) average for a certain layer of water. When interpreting the results, it is useful to bear in mind that, according to Kopelevich ( 1981 ), the suspended coarse fraction contributes 40-45*7^ to light attenuation in the green portion of spectruin in oligotropHic and mesotrophic waters and nearly 80% in littoral waters. It seems quite justifiable to apply the latter assessment to productive littoral waters of high latitudes. In this case, the vertical structure e ,„, will depend mainly on the distribution of suspended coarse fraction, while attenuation index (average for the layer) will be dependent on average content of coarse fraction. Maximum amounts of suspended matter are contained in the Chukchi Sea waters (with absolute maximum found at the area of Stations 55 and 60) and a minimum in the Gulf of Anadyr waters (with minimum found in its southeastern periphery ) ( Fig. 1 ). When assessed in this way, the Bering Sea waters will be in somewhat medium position. This zonal distribution reflects the main qualitative transfomiation that the Pacific waters undergo as they are transported to the Chukchi Sea, with an increase of suspended matter with increasing latitude. Another parameter that is closely associated with average attenuation, with wide application in oceanology, is transmittancy, or maximum depth at which a reference white disk (Secchi disk) is still seen. Such a depth is determined as follows: the disk is gradually immersed deeper and deeper into water, and the depth is noted at which the disk vanishes from sight and then appears in sight again when being raised. The average value H,, found froin the above-mentioned values is termed as Secchi transmittance of water or transmittancy. These measurements are important because transmittancy (associated with all primary hydrooptic characteristics and illumination conditions), in practice, may accurately be expressed in the form of a single uniparametric relationship derived from average value of attenuation ( e ) „,, index in layer O-H: - -A . (13) H., ( f> Proportionality factor A depends on the rest of primary optic properties of water (and, hence, on ocean region) and on illumination conditions. This allows with known a priori 138 valuesof Atoassess( e) |,,Jn those regions where no hydrooptic apparatus-assisted measurements have been carried out but a lot of material on white disk obsei^ation exists. The value of A for waters of the World Ocean varies from 3 to 8 (Ivanov, 1975). However, the calculations made by the author (Levin, 1983) show that under certain "standard" conditions of observation, the range of A depends on the actual variability of optical properties so the range should be narrower. Thus, if the Sun's altitude is more than 60°, and if the disk is observed from the solar board side, the coefficient A for waters having transmitlancy within 5-20 m and oblong indicatrix of scatting (1/k < 0.02). will change almost linearly with the change of probability of photon survival A from 5.1 (with A = 0.06) up to 6.6 (with A == 0.9). Calculations show that the most scattered ocean indicatrices known lower the A value by 10%. When the Sun's altitude is 30° and Ais within the same range, the A value must vary from 4 to 5.5 (if observed from the solar side of board) and from 5 to 8.5, when observed from the shadow side. Slight heaving of the sun will lower the A value to 3-5. From our apparatus-assisted and visual observations, we can assess the value of the proportionality factor for the waters of northern latitudes. Figure 2 shows an experimentally determined function of H,^ in the waters of the Chukchi Sea (triangles), northern area of the Bering Sea (clear circles), and Gulf of Anadyr (solid circles). It is obvious that most turbid waters are in the Chukchi Sea (Hf,= 4-10 m), moderately cloudy waters are in the northern area of the Bering Sea ( H^ = 6- 1 6 m), and relatively clear waters are in the Gulf of Anadyr (H^ = 10-24 m). Figure 2 illustrates two approximating curves plotted according tot 13) fortwo values of factor A (4.3 and 4.8). It is obvious that clear waters of the Bering Sea are more accurately described by (13) when A = 4.3 and turbid waters of the Chukchi Sea at A = 4.8. Discrimination, as manifested by the above-given assessments from the paper (Levin, 1983), may possibly be an evidence of different correlation between absorbing and scattering abilities of suspended matter in different areas. However, this fact can more reliably be borne out by numerous apparatus-assisted and visual observations. Eh-I'^ 1 0 Fig. E,\penmentally found function of H^^ in the waters of the Chukchi Se (A), northern area of the Benng Sea ( O) and Gulf of Anadyr (•). At this stage, the average value of A for northern areas is equal to 4.5. As mentioned earlier, the transmittance of water in the blue-green field of spectrum will depend mostly on the amount of particles present in the water. In productive areas of the ocean, the bulk mass of suspended matter is made up of phytoplankton. Optically, the type of algae can be defined by size, shape, and index of refraction. These characteristics directly affect the angular structure scattered radiation. The bigger size of biological particles and the higher their content in the total composition of suspended matter, the more forward- extended is the water scattering indicatrix and the higher the values of its integral characteristics — asymmetry factor K, mean cosine of scattering angle c"os"y, and portion of light R, scattered in the minor "forward" angle. As waters are carried over by currents from the regions where they formed, the conditions of suspended matter alter, due to the content changes and composition transformers. It is clear that since the latter of the two processes is more inertial, the angular characteristics of light scattering are inore conservative as compared with water transmittance. In this connection, it seems reasonable to determine the totality of angular and integral characteristics that are typical of water in which some species of algae prevail (some peculiar features of such algae being quite typical) and then to employ these characteristics as an indicator for identifying this type of water in the process of its propagation. The transmittance field correlates over lesser areas and can be used to give details in the processes of synoptic nature. Bearing in mind the aforesaid, let us now turn directly to analyzing the experimental data. We shall begin our review with considering the cross sections of transmittance field in the northern waters moving from to lower to higher latitudes. Gulf of Anadyr The crosscurrent Hows northwardly through this region (Sukhovey. 1986). We shall assume that waters at the starting points ofthe area underconsideration are of Pacific origin. The upper layer of water between 60° and 62° north latitude showed clear water in all quasi-latitudinal sections. Such water followed bottom relief and gradually ascended from 100 to 60 m. Beginning approximately from 62°N, the clear water mass was split by a subsurface maximum of cloudiness, propagating northward, to the Gulf of Anadyr. As proved by the analysisof angular and integral characteristics of light scattering, the waters in the area under investigations have high values of asymmetry factor (K = 80- 1 20) and mean cosine (0.95-0.96), an indication ofthe presence of coarse biological particles. Theirrelative volumetric content amounts to 88-92%. A cross section at nearly 63°N (Station 24) has an unusual transmittance structure of water (Fig. 3). In this and other figures, the solid circles show the horizons from which water assays were taken to assess light scattering data. Station numbers and depths from which assays have been taken are given in the figures. In the left-hand column are the asymmetry factor K , relative to volumetric content of suspended matter fine fraction: P= '^f ; R {Yo=2), V, + V,. 139 and small angle value of indicatrix x(y= 1°)- Given as fractions in the right-hand column are volumetric contents V^ and V, in (cmVin') of coarse and fine fractions and also the type of water (Kopelevich, 1983). Here, in the surface 10-m layer of water, there is intense development of diatomic particulates (ocean water was brown). At this station (Station 24), the white disk could be discerned at the depth as small as 3 m. The integral characteristics of light scattering here were also high ( K > 90, cos Y - 0.943 ); as for the coarse fraction, its relative content was somewhat lower (84%). For the purpose of comparison. Fig. 4 shows how chlorophyll a is distributed throughout that quasi-latitudinal section (data from Robie et al., subchapter 5.1.2, this volume). Obviously, there is certain correlation between the two presented structures. It is possible that conditions prevailing at the area of Station 24 were more beneficial for particulates development and that it was just those factors that caused a sharp rise of productivity in originally bioactive Pacific waters. It is noteworthy, however, that these waters give higher values of K and cos y • This can be explained as follows: All light- scattering indicatrices measured in northern waters (all in all about 100 angular relationships had been obtained) were analyzed statistically. The analysis showed the volumetric content of fine fraction increasing with the rise of productivity at a higher rate than that of coarse fraction. In other words, the relative content of the latter drops (which, by the way, was the case at Station 24). Accordingly, the indicatrix becomes less extended and its integral characteristics decrease. Since the water at Station 24 belongs to a very definite type, we shall consider the diatom particulates as having the following characteristics: K = 80-120, cos Y = 0.945-0.960, X,„ = 50-70, R„_,., = 0.1 7-0.22. (14) It is understood that the upper and lower boundaries are reached when the volumetric content of coarse fraction equals 88-92% and 84-85%, respectively. Gulf of Anadyr Littoral Waters Unusual structure of particulates was observed at Stations 26 and 30 at depths of subsurface maximum (15-30 m). Here, the volumetric content of fine fraction comprised more than Section 1 (25) (24) (23) Station No. (22) (21) Fig. 3. Section I. (Stations 2.'i-l9) Vertical strin.turc of transmiltance. 140 50%, but integral and angolar characteristics were tlie lowest (K = 12-13;-Tos Y = 0.77-0.78; x,, , = 44; R,, , = 0.135. Unfortunately, no water assays were taken at intermediate stations. At Station 32, water from the horizon subsurface ma.ximum manifested such integral characteristics of light scattering that are typical of diatomic particulates. This phenomenon can be attributed to the Anadyr River effluence. At Stations 41 and 42 in the Gulf of Anadyr, the transmittance structure was rather primitive; the upper 15-25-m-thick layer was occupied with clear water (e ;: 0.2-0.3 m ' ), and the lower one was more cloudy (e = 0.5-0.7 m '). Bering Sea Northern Region Figures 5-9 illustrate the field of transmittance as seen in the sections of the Bering Sea northern region. Clear water flows through the surface layer at Stations 93, 101, and 103, then runs deeper to 20-25 m ( section 5 ) and flows to the lower part of the right side of the Bering Strait. In the central and western parts of the sections, water turbidity increases up to 0.5-0.7 m '; the subsurface maximum of particulates, which can be traced on horizons 10-20 m, displaces westward with increasing latitude. The integral and angular characteristics of all assays, taken from subsurface and surface water, have the values that are typical of diatom particulates. Note that in the Bering Strait, turbid water with similar characteristics flows only on the left side. Very turbid water was observed in the upper layer of the right side of the strait (section 6), whence it could be traced further to the western part of section 5. This water gradually deepens with decreasing latitude and, in sections 3 and 4, it can be detected only on bed horizons. Its angular and integral characteristics sharply differ (K - 50-60; cos y = 0.91-0.92; X 1 1 1 = 37^5; R, , , = 0. 1 1 -0. 1 2 ) from integral characteristics of light scattering in diatom particulates. Here the relative content of fine fraction comprised 20-30%, with both absolute and relative maximum being on horizon 10 at Station 64. It is interesting to note that in section 2, cloudy water near the bed (see hatched e >1 m ') is of another nature. From isolines 0.9-9.9, it appears that cloudy water is associated with overlying productive waters. Moreover, assaying at Station 104 (horizon 26 m) gives a totality of integral characteristics that correlate with such waters. It is quite possible that it is the divergence of flows, flowing around St. Lawrence Island, that caused local features with water transmittance structure typical of zones where waters are rising. Typical of bottom waters in this section is the distribution of chlorophylls (Fig. 10). Note that clear water at the area of Station 103 is also characterized by definitely lower values of Chi a. Station No. (22) Fig. 4. Section I. (Station,s 25-19) Distribution ol chlorophyll <( (data from Robie t>f tj/.. Subchapter 5.2.1, this volume). 141 Section 6 Station No. 0-1 10 20- Q 30. 40- 50 56.1 Fig. ."i. Section 6. (Stations 82-86) Vertical stnjctureoltransmittancc. "H" and "M" letter codes above refer to Kopclevich water types; the first letter specifies volumetric content of fine particles and the second letter that of coarse particles. Refer to Table 1 for numerical equivalents. Section 5 . (89) Station No. (90) Sla 89-1 Om Sta 69»20m Sta 89'43m Sla 90-1 Cm Sta-91-10m 123 15 1376 62 5 869 51.5 7 35% 0 806 4.8% 0 681 21 5% 1 577 13,3% 0 461 31.8% 1009 0.277 0 06" 0 230 0 066 015 0431 0 182 0 071 0113 0471 90,0 MH 75 IVIH 48.1 HH 59 1 MH 37 3HH Fig. 6. Section 5. (Stations 89-41 ) (See Figure 5 legend.) Vertical structure of transmittance. Chukchi Seci The attenuation intdex fieltd for the Chukchi Sea is shown sectionally in Figs. 1 1-14. The figures show that clear water (e = 0.25-0.4 m') spreads in the surface layer in the northwestern region, anii it gradually moves towards the Chukchi coast with decreasing latitude. Areas of clear water can be traced at the northwestern region and at depths of 25-40 m beneath a thick surface layer of particulates (the core of this layer is shown in these sections densely shaded). Occasionally such portions of clear water occur in the lower interlayers. Also, deep clear water is gradually ousted by the rising bottom water and forced to flow towards the Chukchi coast. As a result, the ousted water merges with a cloudy subsurface layer in the central and eastern parts of the region explored. The angular and integral characteristics of assays, taken from surface and deep clear waters at Station 45, horizons 5, 19, and 28, are very close to and generally compatible with those of watercontaining diatom particulates. The difference lies in higher values of light scattering indicatrices at small angles (x,i > s 95-105), which, when studied optically, suggest bigger "effective" size of coarse fraction scatterers. It should be mentioned that the areas of relatively clear surface water have been recorded at Stations 51,52, 54, 65, and 67. At the areas of its spreading, the average transmittance is somewhat higher, which can be seen in the chart of zonal distribution (Fig. 1. isolines 0.8-0.9 in the eastern part of the region explored). 142 Section 4 (96) (95) .Station No. (94) Sla 96'12m Sla.96'25m Sla 96«40m ^310 0992 ^^^ 0 647 ^^ 3 ^294 ^^°''oo82 ^1 ""'"ooee i^^"'" oTm 0 242 0 209 0 209 85 0HH 70 3HH 76 0 HH (92) Sla 92- 1m Sla92-23m ^207 °°«= 59 1 , ,.. 69,1 HH 45 8HH Fig. 7. Section4. (Stations 96-92) Verticalstructureof transmittance. (See Figure? legend.) Section 3 102) .la 100*5m Sta 100-1 8m 35 9 120 0 Sta 102'5m Sla 102'15m Sla 102'20m "'= 0 370 ^7", °820^" 0 763 °8%-^ f.!!" 0214 !^°, 0168 1%'om 8 25° fi^ 0 224 """^ 0 '60 ° 252 0 058 0 229 """^ 73 3 MM ^^ 5 h 90 3 MH 79 4 MH 0 171 ' 56 5 HH 57 1 HH Fig. 8. Section 3. (Stations 97-102) Vertical structure of transmittance. (See Figure 5 legend.) 143 Station No. (105) (104) 0.285 Fig. y. Section 2. (Stations 106-1U3) Vertical structure of tranMTiiltance. (See Figure 5 legend.) Section 2 Station No. Chi,, (106) _ (105) (1042_ (103) Fig. 10. Section 2. (Stations 106-10,^) Distribution ot'chlorophyllK (data from Robie cfi;/,. Subchapter 5.1.2. this volume). 144 Section 7 (44) ^^^^ Station No. ^^^^ i. 0 314 0-02^ 0 278 0 026 0260 0.039 102 5 93 3 ^^^ 13.3% 0338 0.219 0,052 74.9 (49) (50) ■ 0 . 5 10 15 20 25 30 - 35 40 45 Sta.50«1m Sta 50-45m 76,6 718 14,4% 0399 17,2% 0,794 0193 0.067 0,175 0 165 69 7 61 1 Fig. 11a. Section 7. (Stations 45-50) Vertical structure of transmittance. Section 7 (45) Station No. (47) (48) (49) (50) 4- Fig. 1 lb. Section 7. (Stations 45-50) Distribution of chlorophyll a (data from Robie el ul.. Subchapter 5.1.2. this volume). 145 Section 8 (58) Station No. Fig. 12a. Section 8. (Stations 58-53) Vertical structure of transmittance. Section 8 Station No. (57) (56) (55) Fig. 12b. Section 8. (Stations 58-53) Distribution ot chlorophyll « (data from Robie efo/., Subchapter 5.1.2, this volume). 146 Station No Fig. 13a. Section 9. (Stations 59-65) Vertical structure of transmittance. (60) Station No. (61) (62) (63) (64) (65) Fig. I3b. Section 9. (Stations 59-65) Distribution of ciilorophyH a. (data from Robie e! ai. Subchapter 5.1.2, this volume). 147 The structure of the suspended matter in the subsurface layer had maximum development, as it surfaced, at Stations 34, 55, 56 (possibly 62), and 70. At Stations 55 and 70, the sea was a brown color. The optical structure that is observed here is typical of local divergence zones; most possibly, it is associated with the cyclonic nature of water circulation in this region of exploration (Sukhovey, 1986). The integral and angular characteristics of assays, taken from subsurface maximum, corresponded to diatom particulates and were close to the totality of integral characteristics of light scattering in productive water at Station 34 in the Gulf of Anadyr. The spreading of productive water can be assessed by "fitting" totality ( 14) to integral characteristics of light scattering in all other assays from the Chukchi Sea, thus assessing the areas of productive water spreading. For instance, at Station 53, such water could be traced throughout all depths from surface to bottom. Isoline 1 .0. in the eastern part of section 8, points to a generic relationship between Stations 53 and 55. It is not improbable that here, in the same zone of water upflow, some water flows down the sides. Bottom waters in the Chukchi Sea are very turbid (e > 1 m '). At all stations, where assays were taken from surface and bottom horizons, the highest volumetric contents of coarse and fine particulates, as assessed from (11) and (12), were found at the bottom. Here the integral characteristics of indicatrices had, on the average, relative content of this particulates equal to 1 6-1 7%; at Station 55, this parameter rose up to 23%. An exception was Station 57 where assays, taken from 39 m horizon, gave light-scattering integral characteristics that corresponded to those of productive water. It is certainly of interest that here, as at Station 53, a possible generic relationship between bottom water and productive water of higher layers can be deduced from isolines 0.7-1.0. Figure 15 shows vertical structure of water transmittance as depicted in the Bering Strait section (this section is the closest one by time: 16.08.88). It is evident that most cloudy waters were spreading along western and eastern coasts of the left strait and also along the eastern coast of the right arm. Qualitatively, however, the composition of particulates differed. In the turbid water along eastern coast of the right arm (the intensity of turbidity is depicted by shading of various denseness), the relative content of fine particulates was high (30%); by their light scattering integral characteristics these waters corresponded to earlier examined waters ( sections 3, 4, 5, 6). The coarse and fine fractions here also had rather high concentrations. Turbid waters in the left strait ( shown by dense shading) had integral characteristics that related these waters to the productive ones; relatively clear water spread in the upper layer of right strait into the west. By its integral characteristics, this water corresponded to water with diatom particulates. In the central parts of both arms, in mid-depths, clear water cores (designated as I and 11) were present; these cores differed from the surrounding waters by integral characteristics and transmittance. Fig. 14. Secliun 10. (Slation.s 71-66) Vertical struclure of Iransmiltance. 148 Relationship Between Attenuation Index of Directed Radiation and Chlorophyll Content One of the goals of ocean monitoring is the rapid measurements of parameters such as chlorophyll content. As applied to hydrooptics. the simplest way to attain this objective is to establish statistical relationships between chlorophyll concentration and optical parameters of water. Consider now the attenuation index at wavelength >.=530 nm. The attenuation index was layer-averaged, beginning with surface, and down to the maximum possible depth of probing; chlorophyll content from the surface to the lowest depths sampled. In shallow parts of the sea these depths coincided. (e) and (Chi a). The average attenuation index (i.e., the average content of particulates) was proportional to the average content of chlorophyll (Figs. 1,16). The northern part of the Bering Sea manifested less pigment content in cloudier water. These facts can be easily explained when considering the angular and integral characteristics of light scattering in the areas mentioned. In the Gulf of Anadyr, in the western half of the Bering Strait, and in the Chukchi Sea. the subsurface and middle horizon waters contained diatoms. The eastern part of the Bering Strait has a different particulates composition as judged by integral characteristics of light scattering. Apparently ' the particulates here had lower specific content of pigments; even though the concentration of particles was higher here, the average content of chlorophyll was lower. Now we consider how some quantitative assessments can be derived. Figure 17 shows how (Chi a) relation depends on (e). One can see that relationship between these characteristics bears a dual nature. In productive waters of the Chukchi and Bering Seas, the relationship will be other than that in clear and potentially bioactive waters of the Gulf of Anadyrand in waters with low productivity, such as in the eastern part of the Bering Strait. A useful criterion may be correlation between optical properties of these waters and angular and integral characteristics of light scattering by "developed" diatom particulates. The latter is distinguished by lowest values of P (83-84%). Unfortunately, it is problematic to establish reliable statistics. Because of the lack of experimental points ( we have data on chlorophyll content only for some, not all, stations) and their great dispersion. The latter is partially due to the fact that, for technical reasons, the probing procedure was undertaken 10-20 min after assaying, thus rendering measurements asynchronous. Besides, chlorophyll average content was calculated only on the basis of 5-8 assays. Nevertheless, for a rough estimate, we shall consider that interrelationship between (Chi a) and (e) in productive waters will look as follows: (Chi a) = 12.5(e>-5, in other -(Chi a) = 1.5(e>. In view of higher diatom particulates content in the Chukchi Sea, an attempt was made to calculate a linear regression equation for the current values of e and Chi a. On the whole. Station No. ^ _^^^^^^^ Sla 77 • 44m ^J^^^^ 67 0 Sla 76 • 40m 77 3 9 8% 1545 17°b 1 040 0190 0213 60 9 HH 0 227 0 169 97 5 HH Sla 78 • 10m Sta 78 • 42m 79 5 13 3% 1.138 16 0% 1 070 0 178 0 175 60 0 HH 60 7 HH Sla 79* Im Sla 80 • 26m StaSl • Im 70 6 573 61 6 14 3% 0.522 18 5% 0,571 30 2% ^.rJ^ 0177 0087 0 164 0 152 0 116 0 489 58 0 HH 57.4 HH 37.0 HH Fig. 15. Section 1 1. (Stations 76-81) Vertical structure ot transmittance. (See Figure 5 legend). 149 Fig. 16. Zona! distribution of chlorophyll a average for a certain layer of water (data from Robie el ai. Subchapter 5.1.2, tiiis volume). the result was negative. However, it was found that promising results (Fig. 18) are obtained by comparing relevant values only within the depths of localized subsurface turbid layer, notable also for higher chlorophyll concentrations (Figs. 1 lb, 1 2b, 1 3b). The correlation of current values of e and Chi a can be well expressed by the relation Chi a = 20E+7. Investigating Vertical Structure of Transmittance on Test Areas and Sections East Polygon. Waters at the area of deeply immersed East Polygon stations have a typical subpolar structure of transmittance. The upper 20-30-m layer was turbid (£ = 0.4-1.1 m '); below 50 m, very clear water (£ = 0,13-0.1 m'). At shallow Stations 131 and 132, near the bottom there appeared a thin turbid layer(8 = 0.2-0.25m '). At Station 132, there was a reduced content of particulates in the surfacelayer(e = 0.25m 'compared to £ = 0.6-0.7 m' at Station 131). South Polygon. Optical structures of transmittance at the South Polygon are characterized as subpolar. In the upper 50- m layer, the attenuation index was £ = 0.25-0.3 m ' (at Station 1 10, £ = 0.65-0.7 m '); lower depths (80 m) had clear water (£ = 0. 1 1-0.095 m '). The attenuation index changed gradually in the intermediate layer. Angular characteristics of light scattering showed that the volumetric content of coarse particulates per 10 m depth interval varied from 0.43 cmVm' (Station 1 1 1 ) to 0.59 cmVm' (Station 1 10); fine particulates varied from 0.05 cmVm' up to 0.09 cmVm' (at the same stations). Assays of deep water from 200 to 2,450 m (Station chl a 25 (mg/m ) • Anacjyr Gulf A Bering Sea {nonh area) + East Polygon O Chuckcht Sea /= • St, 24 / / / / / chl a (mg/nf ) /' 70 - 60 - /•20 20/ O Sta, 82 50 - ^y2o • Sta, 74 • Sta. 72 20^ A Sta. 81 40 - /C)l0 V Sta. 97 D Sta. 83 25 / D/ O Sta. 86 30 - %r'' 20 /VA20 20/ 6 7*30 10 - 4 5 e (m Fig. 17. Relationship (Chl a) from (f) in experiment.s. Fig. 18. Dependence Chl ii from within the depths of localized subsurface cloudy layer. 150 112) showed small differences in content. Volumetric content was 0. 1 87 cmVm' and 0.09 cmVm' at 200 m. and 0.218 cm Vm' and 0.04 cmVm' at 2,450 ni. The values are typical of deep waters of the Pacific (Kopelevich, 1981). The Secchi depth varied from 10 m (Station 132; most turbid surface waters) to 15 m (Stations 108, 111). Conclusions Before stating main conclusions, it should be noted that primary hydrooptic characteristics of the Bering and Chukchi Seas were investigated for the first time. The northern Bering and Chukchi Seas were discussed in terms of their transmittance and spatial variability in cross- sectional transects. 1. The transmittance of waters in this study decreases with the increase of latitude. The results of instrument-assisted measurements correspond to visual observations of Hb depths at which a standard white disk disappears ( 1 2-22 m in the Gulf of Anadyr. 7- 1 6 m in the northern Bering Sea, and 4- 1 0 m in the Chukchi Sea). The relationship between H^:, and the average value of attenuation index (ehs) may be expressed by the relationship ,, 45 H. (Eh.) 2. The zonal distribution of average transmittance reflects the dynamics of northern seas. It can be utilized to detect cyclonic eddies and to assess areas where waters have different conditions of formation. 3. Increased turbidity of water is accompanied by a higher rate of fine fraction particulates growth. 4. Waters with different qualitative composition of particulates display distinct angular and integral characteristics of light scattering. This feature enables optical properties of such waters to be used as an indicator in regionalizing the waters by their productivity . It is also helpful when investigating the dynamics of currents. It is shown that diatom particulates in potentially hioactive waters of the cross current increases with latitude. These waters are carried to the Chukchi Sea through the eastern portion of the Bering Strait. In the western portion, it was heavily turbid low-productivity water with relatively high content of fine fraction. 5. The waters in the Gulf of Anadyr and divergence zone in the Chukchi Sea are characterized by high productivity. They show similar values of angular and integral light scattering that are specific for diatomic particulates. This signifies the ability of biological particulates for intensive development in the Bering Sea (where beneficial conditions exist). It may also show affinities between the dynamic processes occurring in both the productive zones. 6. In waters with predominant content of diatom particulates (identifiable as a specific combination of angular and integral characteristics of light scattering ). the chart of zonal distribution of average transmittance correctly reflects ( in qualitative temis) the spatial distribution of chlorophyll content. 7. In high productivity waters of the Chukchi Sea, the relationship between chlorophyll concentration and attenuation index will be Chi c/,,,, = 20e,n,+7. 151 Subchapter 5.2: Zooplankton 5.2.1 Ciliate Protozoa in Plankton NILA V. MAMAEVA Institute oj Oceanology of the USSR Academy oj Sciences. Southern Branch. Gelendzhik. USSR Introduction Methods Intense growth of protozoa was observed throughout the Bering and Chukchi Seas. The maximum Cihophora biomass was found to be higher in the Chukchi than in the Bering Sea. Values were 1.22 and 2.33 g/m", respectively. Most of the infusoria mass occurred in the top 40 m of the water column. Although the taxonomic composition was virtually the same as in 1981, it was substantially different in the two seas. Genus Strombidiitm oligotrichids were predominant in both seas. The degree of Ciliophora development corresponded to chlorophyll levels. Ciliate protozoa are a key factor in the ecosystems of both seas. According to mean data for the layer of maximum concentrations, they may account for as much as 1.5 g of primary nutrient/m Vd circulating in the Bering and 2 g/mVd in the Chukchi. The production yield of ciliate protozoa is 1 g/mVd. Today, as pollution threatens to engulf the world's oceans, the study of sea areas removed from highly industrialized and densely populated regions (i.e.. areas such as the Bering and Chukchi Seas) is becoming of increasing interest to researchers (Izrael&Tsyban, 1983). Thehighly productive waters of these areas are characterized by extremely intense growth of early stages ofthe food chain, especially ofciliate protozoa (infusoria). As the major constituent of microzooplankton. the infusoria serve as a link between the primary food (algae and bacteria) on the one hand and the larger consumer species on the other. Hence, these organisms in large measure drive the transformation of organic matter in the lower stages ofthe food chain. In addition, ciliate protozoa are an excellent indicator of water quality or pollution level. Information about this component of the plankton community of the Bering and Chukchi Seas, however, remains meager. Fraginentary early data (Stepanova, 1937) have now been supplemented by more recent findings (Mamaeva, 1983). The chief purpose ofthe present study, undertaken within the Third Joint US-USSR Bering & Chukchi Seas Expedition in July-November 1988 during the 47th cruise ofthe research vessel (R/V)/4 A«(7('/;h' A: Korolev. was to pursue the investigation ofthe plankton Ciliophoracommunity. Research areas included 1. species composition; 2. quantitative distribution over the water column and sea areas; 3. links with abiotic and biotic factors in the environment; 4. quantitative role in the food chain; and 5. use as an indicator ofthe environmental status of a given sea area. The Bering and Chukchi Seas have extremely heterogeneous ecosystems. Individual areas of both seas are characterized by distinctive hydrological and hydrochemical parameters. This meant that this study had to be conducted in a discrete manner for each individual subarea chosen (Frontispiece). Sampling was performed using Niskin samplers. These were employed following preliminary probing to determine sharp temperature discontinuities and to identify water layers characterized by elevated chlorophyll and suspended matter levels. Parallel determinations were made of biogenic .component levels, pigment concentration, and traditional organic pollutant concentrations. Microzooplankton content was determined conventionally. Immediately upon sampling, 10 ml of the water contained in an oblong chamber were examined under the microscope using a succession of magnifications ranging from low to high. These samples were used to examine and count smaller untrapped forms that perished upon filtering and subsequent treatment of the water. One to three liters of the same sample were then reverse-filtered through a 10- 1 5 ^im mesh in order to isolate the larger protozoa. Samples were likewise taken using nets. Biomass was determined by measuring immobilized infusoria and comparing their shapes with geometric figures and precalculated volume. The specific weight of the organisms was assumed to be the same. The total number of samples taken in the Bering and Chukchi Seas was 350. Results Bering Sea The East Polygon (Frontispiece ) was situated in a complex hydrological setting that included a sharp bottom declivity. Most of the stations had depths of 3.000 m. but the two northernmost ones stood over j ust 1 45 and 2 1 4 m of water. The water contained large amounts of biogenic components: phosphates ranged from 1 .0 to 2.5 |ig al/1 and silicates from 20 to 30 |im at/I. The species mix within the polygon was varied and differed little from ambient conditions (Table 1 ). The predominant forms were smaller Strombidia 15-50 |a in size; the principal Tintinnida were Parafavella denticulate, Ptychocylis umula. and Codonellopsis turgescena. Also common were larger Stobilis, Didinium sp.. Mesodinium sp.. 155 and Suctorida (Table 1). The polygon in question had remarkably abundant infusoria (Fig. 1). In the layer of maximum abundance their numbers ranged from 18 to 67 X 10* individuals/m' and biomass reached 1.2 g/m' (Table 2). Station 2, with the least abundant infusoria, was apparently situated in a strong current. The major portion of the Ciliophora mass lay in the top 40 m of the water column, with two density maxima — one at the surface, the other at a depth of 10-20 m( Fig. 2). The South Polygon lay in the southernmost portion of the Bering Sea, in the vicinity of Aleutian Islands straits, linking it with the Pacific Ocean. The depths at its stations were on the order of 4,000 m, the salinity about 33 %,,. High biogenic component and chlorophyll levels were noted. The hydrological setting was exceedingly complicated, as evidenced by major differences in microplankton content at neighboring stations. The Ciliophora species mix was similar to that of the East Polygon, although some differences were noted. Thus, at Station 1 10, the species typical of the region were joined by Tintinnidium sp. and Cyclotrichium sp., while at the two southernmost stations (111 and 112), near the straits, there were some Steenstrupiella steenstrupii. Since this characteristically Pacific species was seen nowhere else in the Bering, it probably entered the sea through the straits. The quantitative distribution of Ciliophora both here and in the East Polygon was not uniform. Maximum abundance ranged from 1.9 - 36 X lO*" individuals/m' and biomass from 70 to 690 mg/m' (Table 3). Station 113, situated close to the central Aleutian Islands, had the most abundant ciliates. Located near CHUKCHI PENINSULA Bering Sea 109 .108 .110 =^11 *• '112 o o ^ t ^ (3o O Fig. 1 . Infu.soria biomass in the layer of maximum abundance in the East and South Polygons. ILegend:] Biomass in mg/m': 1) 1.220-460; 2)200-116;3)70-2.'5. TABLE 1 List of dominant infusoria taxa for the Bering Sea. Didinium gargantu Meun. Mesodiniiim rubra Lohm. Strombidium strobilis Wiiljf. Strombidium sp. Tontonia appendicularifonnis F-F. Tontonia sp. Leprotintinmts petlucidus { Cleve) Jorg. Codonellopsis tiirgescens K.a.C. Parafavella cylindirca (Jorg.) P. denticulata (Ehrb.) Pnchocylis iimula (C.a.L) Bdt. Canthariella brevis K.a.C. Buldir and Semichi Straits, Stations 1 10 and 1 12 had little microplankton (see Frontispiece). Most of the infusoria mass was localized in the top 40 m of the water column, with maxima at the surface and subsurface layers and at the temperature discontinuity depth of 10-25 m (Fig. 2). TheGulf of Anadyr portion of the Bering Sea is relatively shallow, most ofit less than 100 m deep. The waters of the gulf are a mixture of seawater and low-salinity Anadyr River runoff. The biogenic component concentrations were high, but 0. ,10 0, ,10 0^ ,10 0, ,10 ^125 0, ,200 70 70 0, ,10 0, , 7 0, , 7 0, , 7 0. .450 Oi .360 0. .160 0. .300 fTTt W 2' ^[32 ■ I 35 I 41 0, ^300 J 1100 0, ,170 70 50 y 86 ' I 96 10 0, ,5 0, ,3 0, 0. .300 0, J 100 0. .1 T ^ i Fig. 2. Vertical distribution of infusoria in the Benng and Chukchi Seas. [Legend;] the ordinate axis is depth in m; the upper abscissas are temperature in °C. the lower abscissas the biomass in mg/m'. Solid curves describe temperature profiles. Numbers from 3 to 1 11 refer to stations. 156 TABLK 2 Numbers (N, in 10" of individuals/m") and biomass (B, in mg/m') of infusoria at Bering Sea stations (N/B). Station Depth (m) No. 0 5 10 15 25 45 70 1 60(1/1221 55.4/795 19.5/282 21.9/211 8.6/80 5.5/195 0 2 13.7/323 7.7/39 5.2/24 18.0/116 3.4/1211 1.6/11 0.2/6 3 57.8/623 45.1/508 26.0/464 51.7/752 29.5/375 2.8/24 0 4 58.4/462 32.9/117 41.4/256 13.3/137 3.0/77 4.0/22 0.4/2 5 0 25.0/193 32.2/697 14.2/365 13.5/119 4.5/80 0.8/24 6 13.7/236 66.7/910 39.4/394 57.4/444 40.2/314 58.5/435 12.2/61 7 6.0/180 2.0/60 2.0/60 1 ..3/70 3.5/50 3.5/42 0 9 2.1/70 2.1/70 2.5/82 10.2/94 12.5/75 12.5/60 0 11 46.0/660 46.0/660 58.0/540 12.1/63 64.4/432 0.6/18 3.0/15 13 51.2/336 50.8/324 39.2/276 52.0/360 75.0/790 12.8/84 7.2/36 15 4.0/70 3.0/90 4.6/100 26.1/765 21.2/156 0.5/15 3.0/15 18 2.5/63 3.5/55 6.5/85 2.7/43 1 .6/23 1.0/20 0 19 8.0/115 8..3/259 1.4/17 2.0/100 2.0/60 2.0/60 0 22 5.0/145 5 1 .0/330 27.0/330 26.0/260 1 .5/45 1.2/12 0 24 0.3/9 9.0/90 54.0/420 8.0/235 3.0/40 1.0/10 0.7/18 27 25.0/450 19.0/270 12.0/220 15.0/400 9.0/210 3.8/230 3.5/35 32 7.1/360 30.0/300 28.0/240 9.0/145 9.0/120 2.0/60 0 35 2.0/60 0.5/5 0.5/5 0.3/3 0.3/3 0.2/2 0.5/15 36 5.0/92 2.0/160 2.1/70 5.7/110 2.2/80 0.3/9 0 41 2.6/182 4.1/132 3.0/60 12.0/280 1 .6/55 1 .0/30 0 83 2.85/40 2.15/15 2.10/30 1.07/13 3.21/45 10.0/105 0 86 10.0/235 7.03/120 8.03/140 8.13/160 7.15/210 2.05/25 0 92 3.13/120 2.29/75 2.10/15 2.80/23 0.50/5 0 0 96 16.25/1100 12.05/1040 4.13/280 4.03/130 1 .63/50 2.1/30 0 100 4.25/100 4.10/195 3.10/65 4.25/200 4.50/40 3.50/20 0 102 2.05/15 1 .35/30 1.2/55 1.25/85 2.00/15 0 0 104 8.05/95 2.10/15 2.35/55 4.10/160 2.85/35 0 0 106 2.00/15 2.50/50 1.50/10 0.5/5 0.5/5 2.0/10 0 108 2.15/30 2.53/80 4.05/125 2.08/25 4.1/45 1.65/20 0.53/10 109 0.83/10 8.03/45 6.45/200 4.28/110 4.88/100 1.50/20 0 110 1.50/25 1.90/35 1.20/25 1.60/70 1.00/30 0.70/5 0 111 10.0/200 8.80/190 2.55/75 3.2/100 2.4/30 1.6/10 2.00/20 112 2.80/30 1.50/45 2.43/36 2.83/85 2.03/22 2.05/63 2.0/22 113 36.19/500 35.25/690 14.05/250 10.08/125 5.22/90 1.00/12 0.50/5 markedly lower than in the central portion of the Bering Sea. As with the East Polygon, the predominant species were of the genus Strombidium and ranged from 15-50 |im in size. Throughout the gulf there were the large Strombidium strobilis. the predatory Didinium sp., and Tintinnida ( Ptychocylis iinuda. Pcmifavella denticulata). In contrast to the central sea, brackish- water species ( Tintinuopsis sp. and Leprotintinnuspellucidum ) were also present. The quantitative parameters maintained high values throughout the gulf (Fig. 3). In the maximum- concentration layer, the counts ranged from 6 to 75 X IO''individuals/ni\ The highest Ciliophora densities were observed in the southern portion of gulf. The amount of infusoria present declined considerably as one moved out of this area. The biomass distribution, which ranged from 60 to 790 mg/m' in the layer of maximum concentration, followed the same pattern (Fig. 3). Most of the infusoria were localized in the top 30 m of the water column, with one or two maxima either at the suiface or at a depth of 10-25 m (Fig. 2). Comparative analysis indicated that the infusoria distribution closely matched chlorophyll levels. The most infusoria- abundant stations (Stations 1 1, 13, 15, 19, 24, 27) were associated with an area rich in chlorophyll and phosphates. Ammonia as a by-product of microplankton metabolism was also plentiful. The portion of the Bering Sea situated north of St. Lawrence (Chirikov basin) is shallow with depth ranging from 27 to 49 m. The hydrological setting is very intricate, since it is a zone where three currents (water from the Gulf of Anadyr, Alaskan Coastal water, and water from the Bering Sea Shelf) meet and mingle. The Anadyr water is very salty and cold (temperature ranging down to 2°C at Station 96). Greatly diluted by the Yukon, the Alaskan Coastal waters are of low salinity and high temperature (29.7 ppt and 1 1.2°C at Station 92). These waters undergo only very slight mixing and flow into the Chukchi Sea mostly intact. The flows in the eastern and western portions of the strai t differ greatly in both biogenic element and chlorophyll levels. The coastal waters of Alaska are many times poorer in 157 180° Fig. 3. Distributionof infusoria biomass in the layer of maximum abundance for the Gulf of Anadyr. [Legend: | Biomass in mg/m': 1 ) 790-660; 2) 450-330; 3) 280-60. Numbers from 7 to 41 denote stations. biogenic elements. The heterogeneous character of the flows makes for an exceedingly complicated picture of microzooplankton distribution in regard to both actual species present and their quantities (Figs. 4—7 ). The species composition and ciliate counts for the western and eastern portions of the Bering Strait differed considerably. Dominant in the east were smaller Strombidia and the Tinnopsis sp. characteristic of less saline water. The bottom layers exhibited degraded algal debris, as was confirmed by chlorophyll a level analysis (1.3 mg/1 in the surface layer and 2.7 mg/1 at the bottom). Species variety and abundance were much greater by the western shore. The presence of heterogeneous flows in the Chirikov basin is evidenced by such things as closely placed Stations 100 and 102exhibitingcompletely different infusoria species mixes. The distinctiveness in question remains in evidence all the way to the neck of the strait (Fig. 7). The same may be said of the quantitative characteristics. The infusoria counts and biomass off Alaska were found to be several times lower than off the eastern coast of the Soviet Union (Figs. 4-7). The biomass in the most abundant layerof the strait ranged from 15 to 1,100 mg/m\ with counts from 2.0 to 16.25 X lO^individuals/m'. Thericheststation(Station96) was situated off the western shore, the poorest off the Gulf of Anadyr. Waters within the infusoria-rich stations exhibited high chlorophyll a concentrations (Fig. 7). The same sea areas showed elevated ammonia levels with a maximum of to CHUKCHI PENINSULA _/ ^6 Bering Sea ■63 Fig. 4. Biomass in the layer of maximum abundance for Bering Strait. [Legend:] Biomass in mg/m': 1) 1,100; 2) 280-200; 3) 160-15. Numbers from 83 to 106 denote stations. 2 mg/m'. The distribution of infusoria over depth in this shallow portion of the sea did not conform to any single pattern. With some stations the density maxima occurred at the surface and at a depth of 10-15 m (Fig. 2). The amount of ciliates at several stations increased considerably with depth, whereas in other instances the distribution with respect to depth was uniform. Chukchi Sea The sampling station in the southern portion of the Chukchi Sea constitutes a direct extension of the Bering Sea, inasmuch as three distinct flows enter it through the Bering Strait without undergoing much intermingling. These flows come from the Gulf of Anadyr, the Bering Sea Shelf, and the less saline Alaska Coastal waters (Coachman et cil.. 1975). The area in question is shallow, with depths at particular stations ranging from 35 to 55 m. Water temperature and salinity vary markedly, the water containing high concentrations of biogenic elements. Against a background of intense algal bloom (Chaetoceros, Thalossiosira. Rhizosolenia, and dinoflagellates), the ciliate community of the Chukchi Sea was quite discrete. It consisted of very large (up to 300-|am long) genus Strombidium infusoria, often of brownish and greenish pigmentation, and very large individuals of genera Cyclothchium. Askeiuisia. Didiniiim. Peritromus, elai. Sucking infusoria (Suctorida)andMe'iW/n/w;?! sp. were quite common. Tintinnida were scarce and few in number (Table 3). Clusters of Chaetoceros socialis often included smaller infusoria and dinoflagellates to fomi a kind of microcoenosis. The numbers and biomass of infusoria were very high throughout the region (Table 4, Fig. 8). In the layer of maximum abundance, the counts ranged from 2.5 to 25.1 X 10" individuals/m', and the biomass from 85 to 2,330 mg/m\ higher than in the Bering Sea. The highest 158 Station No. a. 50 -- Fig. 5. Comparison of infusoria biomass (circled, mg/m') with hydrochemical characteristics in the surface layer for Stations 92 and 96 in the Bering Strait. Fig. 7. Chlorophyll concentrations (mg/m') in the layer of maximum abundance for the Bering Strait. [Legend:] 1) 88-67; 2) 3.9; 3) 2.7-1.7. Numbers from 83 to 106 denote stations. Cape Dezhnev Diomedes Cape Prince of Wales Fig. 6. Comparison of infusona biomass (in tnangles, mg/m') with hydrochemical characteristics m the surface layer for Stations 83 and 86 in the Bering Strait. [Legend:] Species; 1 ) Siromhidhtm sirohilis: 2) Sirombidmm sp,; }) Didinuim: 4) A.'^kenasia; 5) Pnchocyiis: 6) Strombidium: 7) Mesodinium; 8) Didinium; 9) Tintiiiopsis. Relative sizes are respected. 159 TABLE 3 List of dominant infusoria taxa for the Chukchi Sea. Didinium sp. Mesodiniiim rubra Lohm. Cyclotrichium sp. Askenasia sp. Peritromus ovalis F-F Strombidium slrobilis Wulff Strombidium sp. Tonwnia appendicidarifonnis F-F. Tonlonia sp. Leprotiiuinmis pelhicidus (Cleve) Jorg. Tintinnopsis sp. Ptychocyiis sp. biomass was noted in the northern portion of the sea (Fig. 8), with vertical distribution varying considerably from station to station. The most frequent case was that of a single maximum, either at the surface or at a depth of 5-10 m. Occasionally the maximum number of ciliates occurred in the 15-25-m layer or at the bottom (Fig. 2). In our view, the high biological productivity of the Chukchi Sea is attributable largely to local processes, because shelf waters are actively enriched by organic matter through primary productivity in the presence of high biogenic levels. Discussion and Conclusions Our study of ciliate protozoa in the Bering and Chukchi Seas showed their development to be extremely intensive, which places both seas among the most productive of the world' s oceans. The ciliate distribution over the sea areas of the •69 •68 •67 -66 1 ED- [z:-3 Fig. 8. Biomass distribution (mg/nV) in the layer of maximum abundance at Stations 45-74 in the Chukchi Sea. [Legend:] Biomass: \) 2330; 2)450-250:3) 198-85. Bering and Chukchi may be described as a mosaic that reflects the heterogeneous character of their ecosystems. The principal mass of infusoria with depth occurred in the top 40 m, with one or two maxima. The species composition and quantitative characteristics of the Bering Sea infusoria during the present study (summer of 1988) were little different from those of spring 1 98 1 , which seems to indicate that the marine ecosystems in question had not experienced much deterioration as a result of human pressure. It was discovered that the Chukchi Sea is TABLE 4 Numbers (N, in millions of individuals/m') and biomass (B, in mg/m- ) of infusoria for the Chukchi Sea (N/B). Station Depth (m) No. 0 5 10 15 25 45 45 1.2U/6U 2.10/150 2.70/115 8.11/350 3.62/180 2.11/116 47 4.31/295 1.10/80 1.15/70 1.70/100 2.15/130 3.50/175 49 4.30/172 6.05/305 5.50/288 5.10/170 2.60/85 2.05/70 50 3.25/180 20.00/827 25.00/1765 17.00/630 5.10/117 1 .00/5 52 16.40/1208 12.05/380 5.14/170 0.50/15 2.30/100 0.70/50 53 25.05/755 15.25/495 24.23/740 25.10/2330 1 .60/60 2.60/25 55 10.20/260 5.10/300 12.70/425 10.10/150 1 .90/48 3.00/150 57 5.10/160 3.20/180 6.10/180 5.20/175 6.37/250 7.00/450 59 1.40/50 2.40/72 4.00/50 5.50/110 1 .00/80 2.50/150 61 2.10/60 3.20/135 4.35/170 2.10/80 3.20/115 5.00/150 64 8.10/220 10.50/320 6.13/285 11.00/270 3.20/30 3.20/180 67 8.00/138 5.40/110 4.20/75 1.6/35 1.00/5 0.80/4 69 2.18/85 1.20/46 0.80/34 1.00/50 2.50/35 1.50/15 72 1.50/100 0.80/34 2.50/35 2.00/70 3.20/100 3.00/90 74 5.13/60 8.10/250 2.10/50 1 .55/20 0.55/10 2.00/100 160 characterized by a very special species mix that includes numerous larger species. A particular microcoenosis was found to occur within Chaetoceros clusters. Also dominant were species of the genus Strombidium. The two seas differed considerably with respect to species structure. The level of ciliate development in the Bering and Chukchi Seas is very high. The maximum biomass in the former case was noted in the East Polygon and in the Bering Strait ( 1 .22 and 1.10 g/m\ respectively). Studies conducted in 1981 yielded similar values. The infusoria community in the Chukchi Sea developed no less intensively, with maximum biomass assays exceeding even those of the Bering Sea. A positive correlation was noted between ciliate biomass and chlorophyll concentration. Areas with very abundant ciliates showed elevated ammonium levels. These levels are a result of metabolic activity. Developing as intensively as they do, ciliate protozoa play a major role in plankton community metabolism in both seas. Thus, in the layer of maximum abundance averaged over the whole of the Bering Sea, they are capable of involving 1 .5 g of primary and bacterial production per cubic meter of water per day in the food chain, yielding 0.5 g of product per cubic meter over the same period. In the Chukchi Sea with a total biomass of 600 mg/m' in the layer of maximum abundance, the corresponding figures are 2 g of organic primary nutrient and 1 g of production, respectively. The findings of the present study indicate that infusoria are reliable indicators of the hydrological and hydrochemical characteristics of seawater. Thus, in the straits in the southern portion of the Bering Sea, we noted infusoria species that pointed to the connection with Pacific Ocean water. Distinct water masses passing through the Bering Strait are characterized both by distinctive species mixes and differing quantitative characteristics. The author is grateful to engineer O. N. Le vina of the Oceanology Institute of the USSR Academy of Sciences ( Southern Branch) for her contribution to the present study. 5.2.2 Characteristics of Zooplankton Communities ANDREY S. KULIKOV Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR Introduction The Third Jomt US-USSR Bering & Chukchi Seas Expedition, on board the research vessel (RA^) Akademik Korolev (July-August, 1988), carried on investigations of mesozooplankton of the Bering Sea that had been started in 1 977 on the Second Joint US-USSR Bering Sea Expedition on the RA' Volna (Izrael, 1983). During the 1988 expedition, investigations of mesozooplankton of the Chukchi Sea were also carried out. Along side previously investigated sampling areas East, North, and South Polygons (expeditions of Kolosovaefa/., 1987; Kulikov. 1990), sampling stations in the Anadyr Bay, the Chirikov basin, and Bering Sea were investigated. Materials and Methods Samples of mesozooplankton were collected with 30-1 Niskin bottles and, at the same time, at the majority of stations, with Big Jedy net (BJN) with 37-cm inlet diameter and filtering cone (168-mm mesh synthetic net). Sampling depths were those determined for combined hydrobiologic research (Timoshenkova & Kulikov, 1988)— that is, 5, 10. 25. 45. 70, and 100 m. Inshallowregions, the lower level was detemiined by the bottom depth at the station. Because of a special investigation of zooneuston carried out during the cruise, no samples from zero level were collected. A BJN was used for vertical tows to 100 m depth. Samples from the Niskin water sampler were filtered through 100-mm mesh gauze. All samples of mesozooplankton were fixed by formalin to the final concentration at 4% in the sample. Identification of species found in the sample and their total number calculation were carried out in a large Bogorov chamber (10-ml) with stereoscopic binocular microscope MSC-9 (LOMO). Samples collected with water bottles were checked for individuals of size range 0. 1-2.0 mm, and samples collected with nets, 2.0-20.0 mm. Fresh biomass was calculated on the basis of average individual weights of organisms and their total number (Lubny-Herzyg, 1953; Chislenko, 1968). Mesozooplankton sampling stations were classified using the polytetic conjugating method of isolated adjunction of hierarchic nonintersectional cluster analysis on the basis of values of Checanovsky-Sjerensen generality indices (Pesenko, 1982) for quantitative data; /,, = min (P-. PJ; (1) where P,j, P,^ is the percent of i species in the total number of mesozooplankton pernr inO-lOOm layer at j- and k-stations; and for qualitative data: 161 /.. 2a (2) (a+b) + (a+c) where a is the number of species common forj- and k-stations; b is the number of species to be found only at station]; and c is the number of species to be found only at station k. Results Species Composition and Species Complexes Seventy-four units of hydrobionts were found as a result of analysis of samples of mesozooplankton collected in the 100-m upper layer of the Bering and Chukchi Seas (Table 1 ). The most diverse and numerous group of organisms — copepods (Copepoda) — counted 26 species and dominated plankton on the majority of stations both in number and biomass. Data in Table 1 shows that epipelagic zones of all of the investigated water areas of the Bering and Chukchi Seas are marked by an active development of populations of two eurybiontic epipelagic species of copepods ( \.e..Pseudocalamus minutus and Oithona similis). Plastic species also could be found in the samples; the hydromedusa Ag/fl/!r/!(7 digitate, appendicularians Oikopleiira labradoriensis and Fritillaria borealis. Some regions are characterized by abundance of individuals of subarctic and boreal species of organisms that form a number of species complexes (Table 2). The calculated regions were defined on the basis of common character of taxonomic composition of the plankton (equation 2). Resultsof J,, cluster analysis are shown in Fig. 1. At the index value of 0.75, the stations were combined into three groups; their geographic position provided for the division of the northern part of the Bering Sea into four regions with relatively homogenous taxonomic composition of mesozooplankton community. Species composition of the southern part of the Chukchi Sea had more similarity than the northern part of the Bering Sea, which is why the fonner was regarded as the region inhabited with taxonomically homogeneous plankton fauna. Distribution of Mass Species Across the Study Region Oithona similis was the most numerous of the investigated populations. It was most developed at the East Polygon, the number of copepodites of this species alone averaged 91 1,000 ind/m-. A somewhat lower concentration was found at the South Polygon — 765,000 ind/m'. The number of O. similis in the northern part of the Bering Sea was considerably TABLE 1 Species composition of mesozooplankton and frequency (%) of occurrence in the Bering and Chukchi Seas. No. Species Areas of the Bering Sea (Station Nos.) South East Gulf of Central Western Eastern Chukchi Sea Polygon Polygon Anadyr shelf of region of region of (108-112) (105) (7.9,11, region Chirikov Chirikov 13.15.24, (18,19, basin (86, basin (83, 27.32,36) 22.35) 69,96,100, 104,106 92,102) PROTOZOA 1. FORAMINIFERA 87 1 RADIOLARIA 62 3. Noctihica sp. HYDROMEDUSAE 31 4. Aglantha digitate 69 5. Aeginopsis taiirenlii 25 6. Ptotocnide borealis 7. Rattikea octopunclata 8. Obetia flabetlata 9. Tiaropsis mutlicirrata 10. Eupliisa sp. 11. Cunine sp. SIPHONOPHORA 12. Dimophxes Arctica 25 13. CTENOPHORA ROTATORIA 6 14. Sxncliat'ta sp. 15. Trichocerca marina 16. NEMERTINI 19 17. Neinaloda POLYCHAETA 18. Tomopteris pacifica 63 19. Thyphloscotex sp. 37 20. Pot\chaita (larvae) 50 77 4 19 27 4 12 12 27 5 2 2 13 6 3 42 162 14 5 27 27 64 27 8 15 4 35 38 100 75 25 17 42 100 20 2 2 42 6 3 55 48 3 92 TABLE 1 - continued MOLLUSCA 2 1 . Gcisliojwda { larvae ) 22. Atlanta sp. 23. Limacina helicina 24. Clione limacina 25. Bivalvia (larvae) CLADOCERA 26. Evudne noidinanni 27. Podon leuckaitii OSTRACODA 28. Conchoecio sp. 31 COPEPODA 29. Calanus cristams 30. C. Piiimchrus 31. C.glacialis 19 23 48 64 32. Eiicalanus hiingii 33. Pseudocalanus miniitus 87 81 97 100 56 8 10 19 33 6 13 15 69 15 10 4 11 44 15 20 14 4 11 31 35 27 88 8 75 58 42 91 2 69 15 12 63 54 40 19 23 48 69 73 58 87 81 97 69 53 50 13 6 63 27 13 25 18 6 18 6 12 69 54 28 31 50 54 32 56 35 23 23 58 25 53 77 25 25 100 100 100 23 22 34. Microcalaiuis pyginaeiis 35. Pleuromamma sculullata 36. Aetidus pacificus 37. Racovitzanus antarcticus 38. Scolecithricella minor 63 27 13 12 39. Eiiiylemoru herdmani 40. E. pacifica 5 41. Metridia pacifica 87 69 67 59 42. Centropages mcmuiricini 2 43. Tortanus discaiidatus 44. Gaetanus intermedins 13 45. Epilaliidocera ampliit rites 46. Acartia Umgiremis 19 46 48 73 47. A. clausi 48. A. tumida 23 49. A. pacifica 50. Oitlwna similis 100 100 95 77 51. O.plumifera 44 19 7 52. Oncaea liorealis 81 81 55 28 53. On. miniita 8 54. Microsetella rasea 81 31 12 55. CIRRIPEDIA (larvae) 6 5 9 HYPERIIDEA 56. Hxperia galba 2 57. Paratlwmisto pacifica 63 35 12 12 58. P. liliellida 3 18 EUPHASIACEA 59. TInsanoessa longipes 6 1 5 60. Til. inermis 25 4 3 61. Euphaitsiacea [\aT\-dt) 25 27 22 14 38 8 28 DECAPODA 62. M(7cn(ra (larvae) 8 3 8 8 5 63. Anomiira [\diWit) 13 5 8 17 16 64. Brar/!/i/ra (larvae) 6 8 25 5 12 11 65. BR YOZOA (larvae) 6 ECHINODERMATA 66. Ophiophitheiis 25 18 32 69 92 75 67. Ophiurasp. 3u\. 6 18 12 68. Echinophitheus 6 12 50 92 63 69. Aiirigularia 19 75 22 CHAETOGNATHA 17 6 27 50 2 58 61 15 83 28 15 50 8 5 100 100 87 15 17 13 46 8 34 96 100 91 58 17 59 9 4 25 85 100 92 70. Parasagitta elegans 69 54 28 55 46 50 44 7 1 . Eiikrohnia liamata TUNICATA 72. Oikopleura labradoriensis 50 54 32 59 73. Fntillaria horealis 74. Ascuiia (larvae) 163 88 92 86 85 100 91 19 9 station Numbers 1.00—1 0.95- 0.90- O o liJ 0.85- 3 < > 0.80- 0.75- 0.70—1 Fig. I. Dendrogram of J^, values (as for qualitative data) at stations in the Bering Sea. Name TABLE 2 Composition of groups of species (complexes) of the Bering Sea mesozooplanivton. Composition South Bering Sea oceanic group (Vinogradov, 1956) North Bering Sea oceanic group (Vinogradov, 1956) Neritic group Anadyr group Calamis cristatus. C. phimchnts. Eucalanus bungii, Microcalanus pygmaeus, Metridia pacifica. Scolecithricella minor. Oncaea horealis. Microselella rosea, Parathemisto pacifica. CalaniLs glaciali.s. Parathemisto libeiliila. . Synchaeta sp., Podoii leuckanii. Evadne tiormanni. Centropages mcmurriclii. Tortanus discaudatus. Eurytemora herdmani. E. pacifica. Acartia longiremis, A. clausi, pelagic larvae of benthic organisms. Euphisa sp., Acartia tumidu. number, indym" inO-IOO(bolloml layer Chukchi Sea Fig. 2. Distribution of Oithoiui .s/mj//i (copepodite stages) in the northern Bering and southern Chukchi Seas. 164 lower than in central and southern regions (Fig. 2). Deep-water stations ofthe region (Stations 7, 1 l.and 15)showedacopepod accumulation density of 330,000 ind/m-. Most probably, conditions of the shelf waters of the Bering and Chukchi Seas exert a negative effect on population development. In the Gulf of Anadyr, western regions of Chirikov basin, and in Bering Strait as well as in the Chukchi Sea, population abundance did not exceed 50,000 ind/m-. Figure 3 shows the character of distribution of levels ofthe Pseudocalanus niinitus population. This species is most developed in the northwest regions of investigations in the Chukchi Sea were the number of P. minutus population reached 470,000 ind/m-. In general, the population of the shallow regions of the Chukchi Sea is two to three times more than that of the Bering Sea pelagic zone. The scattered character spatial location of populations and different sizes of copepods, which are bigger in the Chukchi Sea and smaller in the Bering Sea, suggest that there are at least two separate populations inhibiting the Bering and Chukchi Seas. The size of the Bering Sea population of P. w(>7inkton communilies in the defined region,s of the Bering and Chukchi Seas. Another type of community similar to the Anadyr community was found in the Strait of Anadyr (Station 41). Waters of the Anadyr Current originate in the gulf and flow through the strait. Due to mixing with north Bering Sea Shelf water, we observed a decrease of the content of the south Bering Sea oceanic species that lead to the decrease of zooplankton biomass to 25 g/m- and the increase of content of the appendicularian, Oikopleuni lahnidahensis. Effects of the Anadyr waters that are inhibited with the Anadyr type communities are also marked in the western Chirikov basin and the Bering Strait (Stations 86, 89, 96, 100, 104, and 106; Figs. 19,20). Theaverage values of quantitative indices of the community status of the region are similar to those of the Anadyr Strait. Total number of species was predominantly influenced by eurybiontic species and meroplankton (O. similis. 32<7c:P.minitus. 15'7f;meroplankton, 19%). About 50%ofthe zooplankton biomass of this region was constituted by the south Bering Sea species; 14%, appendicularian O. lahradoriensis; 10%, meroplankton organisms. One can usually find small quantities of the Anadyr complex species. The highly dynamic nature of hydrographic processes in this region cause wide ranges of variability of quantitative zooplankton parameter levels. The amplitude of variation of organism abundance equaled 1 82- 1 ,00 1 ,000 ind/m-, and total biomass, 12-35 g/m-, while the density of plankton conglomerations per cubic meter reached the maximum value for the study period, 1 .4 g at Station 104. The mesozooplankton community in the eastern Chirikov basin and Bering Strait (Stations 83, 92, and 102) was characterized by a predominance of a neretic group of species that includes larvae of benthic animals (73% of abundance and 55% of biomass): copepods Acartia longiremis. A. cleiusi, Centropages memurrichi. Tortanus discaunialus, Eurytemora herdmani, E. pacifica; the cladocera Evadne nordman, and Podon leuckartii. These species are primarily features of the summer season (Kun, 1975). Mesozooplankton samples showed practically no species from the south Bering Sea and Anadyr complexes, nor euphasiid larvae. As a result of formation of numerous agglomerations of small neretic organisms, the total number was considerably larger than that of the western basin and equaled 1.2-2.7 x 10" ind/m', while the biomass was smaller, averaging 14 g/m-. As it was shown above, results of statistic analysis of common character of species composition of the community of mesozooplankton sampled at stations in the southern Chukchi Sea demonstrated qualitative homogeneity of the plankton fauna of the region. At the same time, the structure of the community (i.e.. relative content of elements, their part in the monitored levels of total quantitative characteristics) was marked by considerable differences. Classification of stations on the basis of I,, value calculated according to equation I allowed differentiation into three groups of stations in terms of value of the index of 0.6 (Fig. 21). We should note that, in general, the mesozooplankton community of the Chukchi Sea Shelf was greatly affected by zoocenosis of the northern Bering Sea. It was manifested in the presence of the south Bering Sea oceanic and Anadyr groups of species at the pelagic zone. These groups were transported there most obviously by waters of the Anadyr Current (Coachman et al.. 1975). Although, their number was not significant and never exceeded the average of 5% of the total number and biomass of the community. Density of conglomerations of Ointhoiui similis population in the Bering Sea was at the same level. Mesozooplankton of the Chukchi region of investigation had another common feature; that is, prevalence of pelagic larvae of benthic animals (average of 35% of abundance and 20% of biomass) and Pseudocalanus miniitus (27% of abundance and 14% of biomass). In addition to the pronounced similarity of community structure, there were certain differences in some regions. In the northwest Chukchi Sea (Stations 45, 47, 57, and 59), we detected an intensive development of population of the appendicularian Oikopleiira labradoriensis that totaled 20% of the abundance and 57% of biomass (Figs. 19,20). This formed total index levels that are unusually high for the Chukchi Sea. The structure of community in the northwest (Stations 49, 50, 52, and 53) and south (Stations 69 and 74) regions most of all showed good agreement with the average assessments for the Chukchi Sea in general. Mesozooplankton ,171 station Numbers o M 111 3 _l < > 0.90- 085- 075- 0 70- 060- ©®®®@®®0®©©®®© Fig. 21. Dendrogram of J^^ values (as for qualitative data) at stations in the Chukchi Sea. in this pelagic zone is characterized by mass conglomerations of furcilia of euphaussiids. Their share in the total biomass of zoocenosis averaged 33%. The community of waters of central stations (Stations 55 and 64) was inhabited by meroplankton organisms (45% of number and 30% of biomass ). It is believed essential to note a relatively high amount of appendiculariansfnf(7/aWa borealis, whose biomass exceeded the biomass of another mass species of appendicularians, Oikopleura labradohensis, which dominated in the northwest region of the sea. Discussion Comparison of the study data and materials obtained during previous multipurpose ecologic expeditions of LAM in the Bering Sea in June 1981 and July 1984 (Kosolova et al, 1987; Kulikov, 1990) testifies to an insufficient variability of qualitative and quantitative parameters of mesozooplankton communities as a result of their seasonal development. At the East Polygon (1988, August), the Oithona similis population reached its maximum leading to a 1.5-2.0 increase of mesozooplankton abundance. Total biomass values showed the same rate of decrease due to seasonal migration of older copepodite stages of Calanus plumchrus and C. cristatus. To the west of St. Lawrence Island, in the region of sampling stations of eadier expeditions, at the North Polygon (1988, August — Stations 32, 35, 36, and 4 1 ), we defined a zone with a high level of zooplankton biomass that was formed due to transport of a great amount of large oceanic species of copepods with the Anadyr Current. Compared to July of 1981, the situation has changed. The abundance level decreased three times, while the biomass increased two times. In the southern part of the sampling area there was a similar pattern of variation of organism abundance; still, their peak value was three times larger. Total biomass of community in this region remained relatively the same between the years. 5.2.3 Some Characteristic Features of Epipelagic Necrozooplankton Distribution ANDREY S. KULIKOV Institute of Global Climate and Ecology, State Committee for Hydrometeorology and Academy of Sciences. Moscow. USSR Introduction One of the most important indices of the biological component state of marine ecosystems at the organismic population and community level is biological characteristics, including ecological mortality (Odum, 1975). Ecological or realizational mortality is considered to be the destruction of organisms; in particular, the conditions of the environment and its changing characteristics, in accordance with the firm conditions of habitat and state of affected populations and communities (Koval, 1984). Mortality is expressed both by the 172 number of organisms having died during a specific period of time and by specific death in connection with the whole number of population of organisms (Odum. 1975). The importance of the present trend towards investigation of marine ecosystems is evident. Results from the study of mortality make it possible to estimate a number of functional characteristics of pelagic communities (Beklemishev, 1969; Vinogradov, 1970), parameters of biosedimentational processes (Zhelezinskaya, 1969; Scott, 1977; Stepanov & Svetlichnii, 1978; Lebedewd etal.. 1982), and peculiarities of specific and temporal distribution of plankton animals (Zhelezinskaya, 1968. 1969; Koval, 1978; Kulikov, 1990). Given the large array of negative intTuences by environmental factors, as well as anthropogenic ones, the process of mortality in hydrobenthic research is important in studying the ecological consequences of oceanic contamination (Sheehan, 1984; Izraele/a/., 1989). In this context, it is necessary to note that the show of anthropogenic effects should be preceded by determining the background of natural variability. This is realized by means of long-term baseline investigations in broad regions in the World Ocean (Izrael&Tysban, 1983). Once sufficient data on marine zooplankton mortality levels are accumulated, it is possible to determine the approximate natural mortality levels in individual areas of the ocean, thus making it possible to identify regions of mass destruction of marine organisms. Investigations of A. F. Pasternak in the Black Sea determined that the number of dead mesozooplanktonic organisms averaged 5% of the total number of animals and 2% of their biomass (Sazjin, 1985). Similar characteristics were observed during a period of detailed ecological investigations in the Baltic Sea where the average number of dead copepods was about 5-6% of the numbers and biomass of animals (Kulikov. 1990). Mass destruction of plankton was caused by necrogenic factors from both anthropogenic and natural origins. Intensive losses of marine organisms were discovered in areas exposed to oil pollution (Vinogradov, 1970; Mironov, 1973), as well as areas of unregulated waste discharge ( Grinbart ei al. , 1976). Areas of the Baltic Sea showing levels of sulphurated hydrogen indicated high levels of death in copepods, averaging up to 13% of the total numbers and biomass of the community (Kulikov, 1990). Dead copepods found in frontal areas of upwelling, close to the shore of northwest Africa, reach 1 6% of total numbers (Weikert, 1977). Mortality conditions exist where brackish- water and marine planktonic complexes formed in the fronts oflarge rivers (Beklemishev, 1969; Koval, 1970a,b, 1984). Present investigations into the complex Bering and Chukchi Sea ecosystems were conducted to detemiine the variables of mortality in the population of mesoplankton communities. They will also determine the disturbance areas showing significantly higher concentrations of dead organisms, as well as any reasons for the increases. Materials and Methods Mesozooplankton samples were collected using 30-1 plastic Niskin bottles during the Third Joint US-USSR Bering & Chukchi Seas Expedition aboard the Soviet research vessel Akademik Korolev {iu\y-August, 1988). Permanent depths of sampling were 5, 10, 25, 45, 70, and 100 m. In the shallow areas, the lower horizon was determined by the depth to bottom of the station (Timoshenkova & Kulikov, 1988). Physiological state indicators for organisms were carried out by means of painting samples with neutral or red dyes for the duration of their lifetimes in accordance with Fleming and Couchman"s( 1978)inethod(Crippen&Perrier, 1974). Samples were brought up to a volume of 100 ml and were inserted into glass jars with screw tops. Then 2 ml (0.05% ) of dye was added to each sample ( 1 :2,000) and the capped jars were put into deep water with wastewater extract for the period of 1 h. Samples were then fixed using a neutral formula with a peak concentration of 4%. Calculations measuring differences between dead and live organisms were detemiined by means of a microscope having a 2 x 8 magnification. During the course of study, the following indices were used: number of dead individuals (ind/m- and ind/m'); biomass of dead organisms (mg/m', mg/m-); percent of number, identity, and biomass of dead fraction versus the total number (dead and alive); identity and biomass of the mesozooplankton community (%); ratio of the number and biomass of the dead fraction versus total number (dead and alive); and the biomass types of the total population (%). Since mesozooplankton groups of 0.1-2.0 mm intervals averaged 97% of all communities (of 0. 1-2.0 mm sizes) and their total biomass was 35%, the priority was in the description of the mesozooplankton state at all levels in the pelagic community for the number of characteristics that most fully accessed the situation in the investigated areas. Results The vertical distribution of quantitative indices of necrozooplankton in the euphotic zone of the Bering and Chukchi Seas were distinguished by type as well as the place and location of the station in relation to the hydrographical characteristics of water masses, degree of development of zooplankton communities, depth of layers and their quantitative extremes, etc. Zooplankton numbers differed during the investigations from 0 to 7,500 ind/m' (Station 1 1, 25 m), and biomass reached 100.3 mg/m'. The corresponding contents of dead marine organisms in zooplankton communities varied from 0 to 44.3% (Station 96, 25 m), and biomass varied from 0 to 49.9% (Station 32, 10 m). Some general features of distribution were found. Stations that were situated in more than 2,500 m (Stations 2 and 108, East and South Polygons) had high accumulations of dead animal bodies, up to 2,800 ind/m', were related to the upper warm layer (Fig. 1 ), and coincided with the accumulation of the maximum number of live organisms at that depth. However, the peak percentages of dead animals in the plankton were deeper in the layer of the thermocline, the cold intermediate layer, where their numbers reached 25% of the total zooplankton. Similar vertical distribution characteristics of necrozooplankton were found in the deep region of the continental shelf (East Polygon). At other stations situated on the outer slope of the eastern (East Polygon) and northwestern shelf regions, the highest values of absolute and relative characteristics of the 173 Station 2. 10 20 30 40 % Station 11. 0 1000 _] I I I I I 1 L 2000 3000 ind/r 10 20 30 I 40 3000 8000 J 1 I I - number of necrozooplankton (ind/m ) ^^H - percentage of necrozooplankton in total zooplankton community (%) Fig. 1. Vertical distribution of necrozooplankton at Station 2. vertical distribution of necrozooplankton coincided with depth. At Stations 5, 1 l.and 15, dead organisms were concentrated in the warm upper layer and upper layer of the thermocline ( 10 and 25 m). Here, their numbers reach 7,500 ind/m' which constitutes 34% of the zooplankton (Fig. 2), and biomass was 100 mg/m' or 40% of the total. The vertical structure of necrozooplankton at Stations 7, 9, and 13 were characterized by maxima in the cold intermediate layer (70-100 m; Fig. 3). The accumulation of dead animals numbered 1,100 ind/m' (39%), and biomass. 31 mg/m' (38%). The vertical distribution of necrozooplankton in the shelf regions of the Bering and Chukchi Seas was similar to those found in the deep-water regions. Accumulation of dead organisms, as a rule, was located either at the surface to the discontinuous layer at a depth of 25— 45 m (which divided warm upper and intermediate cold water masses) or to the 70 m layer (where there was a boundary of distribution for intermediate cold and near-bottom warm layers, as at Station 24). In the absence of stratification of water masses (homothennal -and homosalinal) — for example, at Station 96 — necrozooplankton were concentrated in large amounts at the near-bottom horizon, 5,400 ind/m', forming 44% of the total number, and 27 mg/m', comprising 35% of the total biomass. In most cases, significant high absolute numbers coincided in depth with peak percentages of the dead fractions. Analysis of the variability in the levels of quantitative indices for necrozooplankton distribution under a square meter of surface to the layer of 0-100 m enabled the identification of zones with increased concentrations in the Bering and Chukchi - number of necrozooplankton (ind/m ) ^^H - percentage of necrozooplankton in total zooplankton community (%) Fig. 2. Vertical distribution of necrozooplankton at Station 1 1 . 10 Station 13. 20 30 40 % 2000 3000 J I I I I I I L. ind/m - number of necrozooplankton (ind/m') - percentage of necrozooplankton in total zooplankton community (%) Fig. .1. Vertical dislnhulion of necrozooplankton at Station 13. 174 Seas (Fig. 4). The number of dead planktonic organisms at the East and South Polygons changed from 33.100 to 93,400 ind/nr, and the average was 56,900 ind/nr. This feature corresponded with the total amount (3.3%) of zooplankton. Estimated biomass showed a similar percentage of the necrozooplankton. Chukchi Sea (b d) * ® © Bering Sea Fig. 4. Percentage of necrozooplankton in total zooplankton community in the northern Bering and southern Chukchi Seas. The waters of the northwestern part of the Bering Sea differed widely in these characteristics. If, at Station 7, the farthest from the edge of the shelf, readings of both the absolute and related indices coincided with those considered at the East and South Polygons, then theircharacteristics increased several times in those stations situated over the slope of the continental shelf. At Station 11, the number and biomass of necrozooplankton reached the highest value during the period of investigation, to reach 196,300 ind/m- and 1,534 mg/m-, respectively, the percentage of dead organisms to total number of zooplankton was 20%. The frontal zone, which covered water masses composed of deep water and shelf water and extended over the 1 00-meter isobath (Stations 9, 15; Coachman, 1990), differed by low levels of absolute and high levels of relative values of necrozooplankton. At the same time, when the number of dead organisms was not higher than 2 1 ,600 ind/nr, their proportion in the community was 8%. Extreme conditions inhabited by zooplankton communities in the cold water masses of the central shelf region ( including Stations 18, 19, 22, 35, and 36) determined levels of dead organisms. Thus, the number of necrozooplankton, as a result of the total lack of pelagial community, was comparatively low-to-medium, 12,100 ind/m-, though about 7% of the whole community, both by number and by biomass, were not living. The content of dead organisms in zooplankton communities in the waters of the Gulf of Anadyr, Chirikov basin, Bering Sea, and the Chukchi Sea Shelf were negligible and, except in a few individual cases, didn't exceed 5% of number or biomass. Abnormally high mortality rates, with strong evidence of desiccation phenomenon, were seen at Station 96 in the western part of the Chirikov basin. The number and biomass of necrozooplankton at this station were 22 and 19%, respectively. Some increase in mortality of plankton organisms was found in the Gulf of Anadyr, at Stations 24 and 4 1 . The lowest mean levels of indices were found in the shelf waters of the Chukchi Sea. Necrozooplankton in this region averaged 9,500 ind/m-, and biomass, 88 mg/m- ( 1 .7 and 1 .6%, respectively). Lower total background indices were found at the central meridional section line (Stations 50, 55, and 69). The average number of dead organisms at these stations was 21,800 ind/m- (4% ), and mean biomass was 223 mg/m- (4%). The taxonomic composition of necrozooplankton in epipelagic waters of the Bering and Chukchi Seas include the major types of planktonic organisms (Table 1 ) and reflect the regularity of change of the types of live mesozooplankton in the study regions. A majority of the dead organisms ( approximately 80%) belong to two types of copepods, Oithona similis and Preudocaloims minutus (Fig. 5). The correlation of the number % ///// Percent of Oithona similis Percent of Preiidoccilonus minutus Areas I - deep water southwestern area and Continental Shelf of the Bering Sea: II - northern shelf area of the Bering Sea; III - southern area of the Chukchi Sea. Fig. 5. Dominating types of necrozooplankton composition. 175 TABLE 1 Average rates of biomass contents (%) of dead organisms in populations of dominant species of zooplankton in the Bering and Chukchi Seas. [( ) - data gathered at one station of the area.] Sta. Species Southwest Continental Outer .shelf Gulf of Anadyr West part of Central shelf East part of Shelf of the No. deep water Slope. Sta. frontal zone Sta. 24,: 27 the Chirikov Sta. 18,19,22, the Chirikov Chukchi Sea, Sta. 2.4.5. 11 & 13 Sta. 9& 15 32&41 basin. Sta. 35 & 36 Sta. 83.92 & Sta. 45-75 7& 108 86.89,96,100 104 & 106 102 1 Evadne iiorjmanni (79.3) -) Eiicalaniis bungii 7.5 1.1 (100.0) (100.0) (50.4) 3 Pseudoccilaniis minunis 4.8 5.7 1.4 4.7 5.8 7.0 10.5 4.1 4 Microcakmus pygmaeus 2.0 12.0 4.6 (15.9) 5 Metridia pacifica 1.9 8.9 3.9 4.4 3.9 10.2 9.0 6 Acartia sp. 47.4 3.6 2.1 (27.3) 5.4 4.3 7 Acarlia Uimida 1.1 (23.6) 8 Cenlropages momiirrichi (100.0) (25.3) 9 Oilhona similis 4.1 18.0 13.4 3.9 11.6 10.4 4.7 4.1 10 Oncaea borealis 4.9 20.6 9.7 8.5 27.9 1.3 (100.0) -) t 11 Cinipedia lan'ae 16.5 0.2 0.6 12 Echinodennata lan'ae (95.3) 1.2 13 Frilillaria borealis 11.9 2.9 2.5 of dead to living species types depends upon the degree of development of the population. In the upper deep-water regions in the Bering Sea, as well as the outer zone of the northeastern shelf, the size of the dead population of O. similis averaged 80% of the total number of necrozooplankton, while the size of the dead population of P. ininutiis was only 6%. The shoal waters in the shelf of the Bering Sea contained 49% and 27%, respectively, of these dead organism types. In the Chukchi Sea, dead populations of P. mimitiis predominated (61%). A number of other major types, such as Eucalanus bungii (juveniles), Microcalanus pygmaeus. Metridia pacifica. and Acartia sp., also contributed significantly to the fomiation of zooplankton accumulation; in higher latitudes, Onacea borealis made up about 10% of the total number. At the stations listed above, the structure of the necrozooplankton was destroyed and dominance was gained from types whose dead species were rarely found. In the western part of the Chirikov basin (Station 96), 73% of the dead portion of organisms were echinoderm larva; in the Gulf of Anadyr (Station 27), 36% were dead specimens of the neritic copepod. Acartia tiimida. Data collected on the death of specific populations of marine organisms will enable understanding of certain features of ecological relations in the study areas of the Bering and Chukchi Seas. These data are connected with the inass destruction as a result of the influence by negative external factors. In our opinion, the population condition of major types in the deep-water regions of the Bering Sea was favorable. There was a comparatively low population of dead organisms found in these areas, 5% on the average. The exception was a number of neretic copepods./lcnrrfV/ sp., that constituted about half of the dead organisms in the biomass. High mortality was found in O. Iwrealis and O. similis — 23% and 30%, respectively. Similar situations to the two species noted were found in the middle front zone of the northwestern shelf of the Bering Sea ( 100 m). The western part of the Chirikov and the Gulf of Anadyr was the area of highest mortality. The high content of dead organisms belonged to populations such as Eucalanus bungii. Microcalanus pygnwnus. Centropages memurrichi. Acartic tumida, and Frilillaria borealis. At Station 96, the dead population was 76% E. nordmanni. 43% O. similis. 73% O. borealis. and 95% echinoderm larvae. Populations of major oceanic types were affected by the strong influence of illumination in the total area northern shelf of the Bering Sea. The high mortality level, up to 14% inareasof shelf water mass (central shelf area and eastern part of the Chirikov basin), is a characteristic feature of populations of P. minutus. The shallow shelf of the Chukchi Sea had low averages of necrozooplankton. The only high mortality rates found in this area were for Metridia pacifica. 87% (Station 55); Eucalanus buugii. 50% (Station 55); and Oithona similis. 17% (Station 45). Conclusions During the investigation, the number and biomass of dead organisms varied widely, from 0 to 7.500 ind/m- and 100.3 nig/m\ respectively. The content of zooplankton communities reached 44.3% in number and 46.9% in biomass. The nature of the vertical distribution of necrozooplankton depended on the position of the stations. At deep-water stations (more than 2,500 m), dead remains of organisms accumulated, through the process of biosedimentation; in colder deep layers, these remains were from animals that died in the upper warm layer, the layer of highest concentration of living organisms. At the majority of the stations situated on the outer shelf of the eastern and northwestern Bering Sea, necrozooplankton concentrated in the horizons where mortality occurred. The reasons for this may be low biosedimentational rates or the high intensity of organism death. In the stratified waters of the shallow shelf regions of the Bering and Chukchi Seas, the ratio of dead animals was related to water mass boundaries, due to the absence of near-bottom horizons. Highest levels of 176 necroplankton relative to communities in the northwestern part of the Bering Sea were, at the outer continental shelf, 20% of the total number; at the frontal zone over the 100-m isobath, 8% of the total; and 7% of the total in the cold water mass of the central shelf area. These regions are joined either by extreme characteristics of the plankton community in the North Bering Sea Shelfand Pacific basin or in the extremely low temperature conditions of the water, which are near freezing. In the deep water area of the Bering Sea, the condition of the major oceanic populations were normal. The average of total dead specimens was 5% of total numbers. On the outer and northwestern shelf of the Bering Sea, the population of oceanic species appeared here together with Anadyr Curtent waters. As a result of the impact of unfavorable factors and intensive illumination, it is necessary to note that there is a high level of dead organisms of both oceanic and neritic types associated with the Anadyr Current. In the Chukchi Sea, necrozooplankton were at background levels with low mean values found during the entire period of study. 5.2.4 Carbon Isotope Ratios in Zooplankton as Markers of Aging and Habitat Usage for the Bowhead Whale (Balaena mysticetus) DONALD M. SCHELL, NORMA HAUBENSTOCK, and KIMBERLY A. VINETTE Institute of Marine Science. University of Alaska. Fairbanks. Alaska. USA Introduction The Third Joint US-USSR Bering & Chukchi Seas Expedition was used to obtain zooplankton samples from the two seas for stable isotope abundance studies. This paper presents the d"C and d'^N data acquired from the cruise on board the Soviet research vessel Akademik Korolev, in context with pre vious data on stable isotope values in arctic zooplankton. Although the nitrogen isotope data are also listed, we have confined the discussion to the more comprehensive carbon isotope data. Recent findings have shown that distinctive gradients exist in the stable isotope ratios of carbon in zooplankton from the Bering to the eastern Beaufort Seas. With increasing latitude, the heavier isotope is less abundant in the phytoplankton and this "signature" is passed up the food chain. We have been using these natural tracers to determine critical feeding habitats for bowhead whales (Balaena mysticetus) and to aid in separating US and USSR polar bear stocks that commingle in the Chukchi Sea during the winter months. The work on bowhead whales has been described in Schell et at. (I989a,b) and Saupe et al. (1989). The study on polar bears is still in progress. Isotope Ratios in Food Web Studies Ecosystem studies involving biochemical systems usually depend upon two approaches. One approach is to construct budgets or mass balances of a key element and attempt to determine which fluxes dominate these budgets. The second approach measures the key rates or processes within the system and then attempts to relate the findings to the overall goal. Although ideally the two approaches should be complementaiy and finally coalesce into abetter understanding of the ecosystem, this goal is usually difficult to attain. There may be mismatches between time and space scales of the two approaches or processes that cannot be determined to the required accuracy. Many of these quandaries are evident in any attempt at estimating the feeding requirements of bowhead whales. Because stable isotope ratios can contribute both source (tracer) information and process information, they are ideally suited for the measurement of elemental movements, which in this case is carbon. The field of stable isotope tracers has steadily expanded and a wealth of information on terrestrial and aquatic applications is now available. Fry and Shert (1984) and Peterson and Fry ( 1 987 ) review these applications and discuss the strengths and weaknesses of the many studies. There will be no attempt here to review all of these applications, but several pertinent findings will be presented. Rundel et al. ( 1989) presented a series of papers on various applications including several multiple isotope tracer studies. The fidelity of consumers to the isotopic compositions of diet underlies all ecological studies using stable isotopes. DeNiro and Epstein ( 1 978 ) plotted diet versus consumer isotope ratio and found that the transfer was conservative with regard to the whole animal. A small enrichment occurs of about one part per thousand per trophic step, typically slightly larger with herbivores and less with carnivores. This has been documented in both field and laboratory studies (see review by Peterson & Fry, 1987; McConnaughey & McRoy, 1979). A succinct report by Jones et al. (1981) documents the change in isotope ratios of cattle fed C-3 plants, then changed to C-4 plants, and then switched back again. Within 70 days, newly grown hair had reached equilibrium with the new diet after each change. Since the hair required several days to reach the surface of the skin following shaving, actual response was faster than the isotope ratios in the shavings indicated. 177 Within organisms, the complex pathways of biosynthesis can alter the isotope ratios in the end products relative to starting materials. The distribution of carbon isotopes has been studied by several authors (DeNiro & Epstein, 1978; Jones etai, 1981; Tieszen et al., 1983; Mizutani & Wada. 1988). Muscle tissue tends to closely approximate diet whereas keratinous proteins (hair, feathers, and hooves) are typically enriched by 2-3 "/,„ relative to diet. Schelle/ a/. (1989b) found that keratin in baleen averaged about one part per thousand heavier than muscle, which in turn was about 6 7,),) heavier than lipids. Polarbears, which are l-2trophicIevelsabovebowhead whales, also show an enrichment in keratin 5"C of 1-2 "/„, relative to the whales. As more and more studies are performed on ecosystem processes, the usefulness of stable isotope ratios as tracers has become increasingly evident. Background The initial work on this project commenced in 1985 and sought to establish the significance of the eastern Alaskan Beaufort Sea in the annual energy budget of bowhead whales. One approach to answering this question was to use the geographical differences in the stable isotope ratios (carbon and nitrogen) in whales and their prey organisms as natural tracers of food sources. Natural history investigations of the large baleen whales present formidable problems due to the difficulties in observing the animals in their natural environments. Schellt'?fl/. ( 1989a) demonstrated, however, that bowhead whales have marked annual oscillations in stable carbon and nitrogen isotope ratios along the length of the baleen plates in the mouth. These oscillations result from the annual migration of the animals from wintering grounds in the Bering Sea to the summering areas of the Canadian Beaufort Sea. Zooplankton along the migrational path have differing isotopic ratios of carbon and nitrogen, which are reflected in the composition of the keratin in the continuously growing baleen plates. Since up to 20 years feeding record may be present in the plate of a large bowhead whale, considerable insight may be gained on the natural history of the whales and their habitat usage. We have reported (ScheW etal., 1989a.b;Saupec/«/.. 1989) on the isotopic ratios in zooplankton prey that produce the large variations in B. mysticetiis and a revised growth rate for B. inystlcetus, detemiined through isotopic aging techniques. The stable isotope abundances in baleen oscillate in a regular pattern along the length of the plate in response to the compositional changes in the whale food (zooplankton) as the animal migrates. The isotope ratios in the baleen — and especially in the muscle and visceral fat of animals killedin the spring compared to those killed in fall — show that the greatest amount of food consumed by B. mysticetiis matches the isotopic abundances typical of prey species in the western and southern areas of the migratory range. The average "C isotope value in visceral fat and mu.scle tissue from spring-killed B. mysticetiis was enriched by 2.1 "/(,,, relative to two fall-killed animals, implying that a major fraction of the total carbon of the animal was derived from the western and southern parts of their annual range. Although it is impossible to accurately estimate the relative amounts of food that the whales obtain from the Beaufort versus Chukchi versus Bering Seas (because of the close similarity of zooplankton isotope ratios in the Bering and Chukchi), these data contrast with previous feeding scenarios that suggested that bowheads fed in the summer in the eastern Beaufort Sea and relied almost entirely on stored reserves for the winter (Lowry & Frost, 1984). The isotopic data from three adult whales analyzed indicate that these large whales have an average isotopic composition derived from prey obtained almost entirely in the western and southern parts of their range (Schell ??«/., 1989b). This might mean that the eastern Beaufort Sea is not nearly as important a feeding area for this segment of the population as the western Chukchi and the Bering Seas. The findings listed above are based on a limited number of whale samples. Nevertheless, the resuhs are sufficiently contrary to previously accepted growth rates and feeding scenarios that it is important that the data base be expanded to substantiate or disprove the indicated findings. The work performed on the cruise in 1988 sought to expand the zooplankton data from around the range of the bowhead, especially from the missing areas in the western Chukchi and the northwest Bering Seas, and to provide further insight regarding the cause of the isotopic shift between the southwestern and northeastern segments of the migratory range. The data collected on this cruise are part of the necessary samples required to fill the data gaps in the natural history of important marine mammals living in waters shared by the United States and the Soviet Union. Objectives of the 1988 Akademik Korolev Cruise Our overall goal was to use the isotopic gradients in the Bering-Chukchi-Beaufort Seas to determine the habitat dependencies and feeding strategies of the bowhead whale. By comparing the carbon isotope ratios in bowhead tissues with that in their prey organisms along the migratory route, we can establish, at least qualitatively, the importance of the various habitats to the animals. The objectives of this expedition were to; /. Obtain zooplankton for isotope analysis from the western (USSR) sector of the Bering and Chukchi Seas for comparison with zooplankton from eastern waters. 2. Interpret and synthesize new data in context with past findings to confirm or deny current interpretations of bowhead whale natural history with special reference to the role of the Bering-Chukchi Seas as feeding habitat. Methods Zooplankton were collected using ring nets with 505 mesh at the stations shown on Fig. 1 and listed in Table 1. Upon collection, samples were sorted to major taxonomic groups and to species where identification was feasible in the field. Samples were then frozen for later processing in the laboratory at Fairbanks. Procedures for sample handling and mass spectrometry are described in Schell et at. ( 1987). Milligram amounts of dried zooplankton were ground with CuO ( 750 mg) and sealed into evacuated quartz tubes. Following combustion 178 at 900°C for 1 .5 h, the tubes were cooled and opened on a high- vacuum hne. The carbon dioxide and nitrogen gases were cryogenically separated and the ratios of "C:'-C and "N;'^N determined with a VG ISOG AS isotope ratio mass spectrometer. Fig. 1 . Station locations and distribution of euphausiid 6"C values from the 1988 Akademik Korolev cruise. Average 8"C values listed are from Chukchi-Bering, western and eastern Beaufort Seas from 1985 to 1988. (from Saupefdi/., 1989). Results and Discussion The samples collected from \hc Akademik Korolev in 1 988 are listed in Table 1 . The data confirm the general patterns found by Saupe el al. (1989) and show that a consistently enriched 5"C fauna are present in the Bering Sea relative to the Beaufort Sea. The data were separated into general taxonomic groups and compared by region (Chukchi Sea versus Bering Sea) and by subregions (eastern versus western Bering Sea, etc.) using nonparametric statistics. The comparisons showed that no significant regional differences exist in the isotope ratios of the zooplankton from the Bering and Chukchi Seas. Although the samples span both the Anadyr and Alaska Coastal water masses, no significant difference was found between any of these adjacent waters. However, there are significant differences in the isotopic ratios when similar taxa are compared from the Bering-Chukchi region and the eastern Beaufort region. Figures 1 and 2 show 5"C values for euphausiids and copepods from the stations sampled on board the Akademik Korolev. These data are compared with the previous findings by Saupe «-? «/. (1989). The isotope data do reveal that the mean 5"C values of both copepods and euphausiids were depleted by approximately 1 °/„, when compared to the Bering Sea data of Saupe et al. ( 1 989 ). Also substantiating the findings of Saupe et al. ( 1 989), the euphausiids were again enriched by l.l°/oo relative to copepods from the same area. The lack of regional differences in the Bering-Chukchi data would seem to indicate that the observed depletions in the 1988 samples were areawide. It is noteworthy that the 5"C values in the baleen plates of the bowhead whales collected over the past few years show multi- year trends that are similar between animals. This would indicate that the shifts in 5"C are caused by an environmental or floristic change at the priinary producer level and are not due to shifts in biomass fraction in the zooplankton prey of the whales or shifts in feeding preferences by the whales. We do not yet know the cause of these changes. Fig. 2. Station locations and distribution of copepod 5"C values from the 1 988 Akademik Korolev cruise. Average 5"C values listed are from Chukchi-Bering, western and eastern Beaufort Seas from 1985 to 1988 (from Saupe el al. 1989). 179 TABLE 1 Samples collected from the Akademik Korolev in 1988. TAXA STATION LAT. LONG. S'^C 5"N °N °W (-"/,« ) ("/,„ ) Ampelisca sp. 61 67 20.0 169 45.0 8.58 Ampelisca sp. 69 67 00.0 168 43.9 19.18 9.36 Amphipod. Gainmaridae 45 67 44.0 172 50.0 19.60 Amphipod, Gainmaridae 59 67 09.2 172 59.8 I/.86 13.47 Amphipod, Gammaridae 100 64 22.6 169 10.9 12.27 Amphipod. Gainmaridae 100 64 22.6 169 10.9 20.22 8.17 Amphipod, Gainmaridae 25 64 00.0 179 20.0 19.99 8.50 Amphipod, Gainmaridae 61 67 20.0 169 45.0 17.76 12.19 Amphipod, Hyperiidae 6 59 30.0 179 30.0 21.71 8.20 Amphipod, Hyperiidae 104 63 50.7 169 12.3 9.54 Amphipod, Hyperiidae 38 63 55.0 173 35.0 21.62 9.58 Amphipod, Hyperiidae O") 63 00.4 176 00.1 24.82 11.57 Amphipod, Hyperiidae 20 62 34.7 175 03.5 23.68 Amphipod, Hyperiidae 32 64 00.0 175 00.0 22.19 9.85 Amphipod, Hyperiidae 95 64 58.2 169 58.6 21.60 11.23 Amphipod. Hyperiidae 11 61 35.0 178 39.0 20.61 11.56 Amphipod, Hyperiidae 40 64 07.5 172 32.2 22.85 9.90 Amphipod, Hyperiidae 9 61 20.1 176 03.2 22.36 12.01 Amphipod, Hyperiidae 107 64 23.0 171 39.0 22.01 Amphipod, Hyperiidae 13 62 II.O 17951.0 21.88 11.03 Amphipod. Hyperiidae 110 53 55.6 I76 00.0E 24.87 Amphipod, Hyperiidae 27 64 43.3 177 48.2 21.23 9.98 Amphipod, Hyperiidae 88 65 21.6 169 59.3 23.22 Amphipod, Hyperiidae 86 65 56.3 169 22.9 23.75 Amphipod, Hyperiidae 74 66 33.0 168 36.0 23.16 Sagitia elegans 47 68 06.0 170 53.0 20.74 12.82 Sagilta elegans 22 63 00.4 176 00.1 22.63 11.98 Sagitta elegans 107 64 23.0 171 39.0 21.29 9.96 Sagitta elegans 61 67 20.0 169 45.0 20.19 11.18 Sagitta elegans 56 67 44.2 169 55.6 21.27 8.84 Sagitia elegans 58 67 30.5 172 11.4 20.33 12.58 Sagitta elegans 6 59 30.0 179 30.0 22 22 11.33 Sagitta elegans 96 65 05.0 170 44.0 21.45 Sagitta elegans 110 53 55.6 I76 00.0E 23.99 Sagitta elegans 86 65 56.3 169 22.9 20.40 10.94 Sagitta elegans 9 61 20.1 176 03.2 21.58 15.13 Sagitta elegans 85 65 50.0 169 10.0 20.92 10.70 Sagitta elegans 32 64 00.0 175 00.0 21.36 14.84 Sagitta elegans 73 66 44.0 171 05.0 19.92 13.53 Sagitta elegans 60 67 15.7 170 49.6 20.73 Sagitta elegans 50 68 39.7 168 20.0 20.22 11.20 Sagitta elegans 11 61 35.0 178 39.0 21.30 11.01 Sagitta elegans 38 63 55.0 173 35.0 21.24 11.65 Sagilta elegans 13 62 II.O 179 51.0 21.16 12.66 Sagitta elegans 19 62 25.5 174 00.2 20.67 11.93 Sagitia elegans 20 ^' 62 34.7 175 03.5 22.26 15.49 Sagitta elegans 87 65 24.5 170 21.5 11.39 Sagitta elegans 95 64 58.2 169 58.6 20.50 12.68 Sagitta elegans 64 67 17.8 166 42.6 22.17 10.78 Composite Zooplankton 47 68 06.0 170 53.0 21.61 8.98 Composite Zooplankton 87 65 24.5 170 21.5 20.52 9.28 Composite Zooplankton 85 65 50.0 169 10.0 22.14 10.89 Composite Zooplankton 86 65 56.3 169 22.9 20.85 10.44 Composite Zooplankton 71 66 44.0 171 05.0 9.69 Composite Zooplankton 97 64 44.9 171 29.7 21.45 9.41 Composite Zooplankton 40 64 08.0 172 30.0 21.99 9.89 Composite Zooplankton 57 67 42.6 171 20.7 21.14 8.96 180 TABLE 1 - continued Samples collected from the Akademik Korolev in 1988. TAXA STATION LAT. LONG. 5"C 5''N °N °W (-"/,., ) ("/,„ ) Zooplankton 70 66 55.0 169 55.0 19.54 8.73 Zooplankton 99 64 32.0 17001.0 21.19 10.50 Zooplankton 38 63 55.0 173 35.0 21.15 9.15 Zooplankton 104 63 50.7 169 12.3 21.52 10.72 Zooplankton 27 64 43.3 177 48.2 19.32 8.61 Zooplankton 107 64 23.0 171 39.0 20.30 10.29 Zooplankton 78 65 51.0 169 13.0 21.77 9.69 Zooplankton 88 65 21.6 169 59.3 20.85 10.84 Zooplankton 25 64 00.0 179 20.0 18.92 8.76 Zooplankton 64 67 17.8 166 42.6 20.97 9.05 Zooplankton 58 67 30.5 172 11.4 19.68 8.32 Zooplankton 6 59 30.0 179 30.0 22.62 7.07 Zooplankton 42 63 55.2 172 04.4 22.80 9.67 Zooplankton 98 64 43.1 170 52.4 22 24 9.58 Zooplankton 32 64 00.0 175 00.0 23.38 9.92 Zooplankton 13 62 11.0 17951.0 23.04 10.45 Zooplankton 95 64 58.2 169 58.6 22.68 10.44 Zooplankton 50 68 39.7 168 20.0 21.45 11.68 Zooplankton 20 62 34.7 175 03.5 11.76 Zooplankton 106 64 14.0 1 70 54.7 22.50 9.91 Zooplankton 9 61 20.1 176 03.2 24.16 10.17 Zooplankton 11 61 35.0 178 39.0 23.45 10.69 Zooplankton 96 65 05.0 170 44.0 22.04 11.33 Zooplankton 67 66 56.0 165 50.0 20.65 10.68 Zooplankton 110 53 55.6 176 00.0E 25.87 Zooplankton 35 63 00.0 173 00.0 23.34 12.12 Zooplankton 22 63 00.4 176 00.1 11.04 72 66 44.0 171 05.0 22.90 96 65 05.0 170 44.0 22.34 11.77 35 63 00.0 173 00.0 23.61 12,27 22 63 00.4 176 00.1 24.25 10.99 50 68 39.7 168 20.0 21.98 12.47 9 61 20.1 176 03.2 24.18 10,62 45 67 44.0 172 50.0 20.98 10.60 40 64 08.0 172 30.0 8.37 47 68 06.0 170 53.0 20.62 10.72 67 66 56.0 165 50.0 22.29 14.18 58 67 30.5 172 11.4 20.61 10.78 25 64 00.0 179 20.0 19.25 10.86 104 63 50.7 169 12.3 22.79 10.47 20 62 34.7 175 03.5 23.57 13.54 55 67 44.1 168 26.4 21.25 10.63 98 64 43.5 171 11.0 21.73 11.57 59 67 09.2 172 59.8 21.80 10.43 64 67 17.8 166 42.6 22.12 13.95 74 66 33.0 168 36.0 21.78 10.87 57 67 42,6 171 20.7 20.73 10.34 85 65 50.0 169 10.0 23.64 10.72 61 67 20.0 16945.0 22.04 11.21 6 59 30.0 179 30.0 22.91 7.52 42 63 55.2 172 04.4 22.99 88 65 21.6 169 59.3 23.22 11 61 35.0 178 39.0 23.20 27 64 43.3 177 48.2 20.82 8.10 86 65 56.7 169 22.9 23.12 7.89 32 64 00.0 175 00.0 23.34 6.89 Composite Composite Composite Composite Composite Composite Composite Composite Composite Composite Composite Composite Composite Composite Composite Coinposite Composite Composite Composite Composite Composite Composite Composite Composite Composite Composite Composite Calanus sp Calaiuis sp Calanus sp, Calanus sp Calanus sp. Calanus sp. Calanus sp Calanus sp Calanus sp Calanus sp Calanus sp. Calanus sp Calanus sp Calanus sp Calanus sp Calanus sp. Calanus sp Calanus sp Calanus sp Calanus sp Calanus sp. Calanus sp. Calanus sp Calanus sp Calanus sp Calanus sp Calanus sp. Calanus sp, Calanus sp. 181 TABLE 1 - continued Samples collected from the Akadanik Koiolev in 1988. TAXA Calanus sp. Calaiuis sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Cahuuis sp. Calanus sp. Calanus sp. Calanus sp. Calanus sp. Euphausiid STATION LAT. LONG. 5"C ?,"N °N °W (-"/,„ ) ("/,„ ) 107 64 23.0 171 39.0 23.34 8.07 87 65 24.5 170 21.5 21.35 10.51 104 63 50.7 169 12.3 22.85 97 64 44.9 171 29.7 22.42 8.44 70 66 55.0 169 55.0 23.22 25 64 00.0 179 20.0 20.67 8.93 38 63 55.0 173 35.0 22.99 6.58 95 64 58.2 169 58.6 22.60 10.59 110 53 55.6 176 00.0E 26.77 85 65 50.0 169 10.0 22.61 8.57 98 64 43.5 171 11.0 22.12 11.80 6 59 30.0 179 30.0 24.70 8.58 70 66 55.0 169 55.0 22.08 15.00 13 62 11.0 179 51.0 22.21 12.15 40 64 08.0 172 30.0 22.62 9.75 87 65 24.5 170 21.5 20.88 9.90 107 64 23.0 171 39.0 21.67 12.59 76 65 58.0 169 35.0 22.30 11.14 11 61 35.0 178 39.0 21.71 9.21 27 64 43.3 177 48.2 22.07 7.28 25 64 00.0 179 20.0 20.44 9.46 110 53 55.6 176 00.0E 25.27 61 67 20.0 169 45.0 21.20 9.11 32 64 00.0 175 00.0 21.05 8.57 38 63 55.0 173 35.0 22.31 10.73 110 53 55.6 176 00.0E 25.63 3.97 40 64 08.0 172 30.0 21.99 10.25 11 61 35.0 178 39.0 23.53 10.54 6 59 30.0 179 30.0 22.87 5.77 97 64 43.5 171 11.0 23.29 7.46 6 59 30.0 179 30.0 22.16 7.67 27 64 43.3 177 48.2 20.83 8.27 32 64 00.0 175 00.0 9.78 25 64 00.0 179 20.0 21.78 6.93 38 63 55.0 173 35.0 21.30 9.01 88 65 2 1 .6 169 59.3 23.71 70 66 55.0 166 55.0 22.12 10.60 19 62 25.5 174 00.2 22.69 14.88 85 65 50.0 169 10.0 22.40 9.55 42 63 55.2 172 04.4 23.62 56 67 44.2 169 55.6 21.16 10.66 107 64 23.0 171 39.0 21.46 10.22 60 67 15.7 170 49.6 20.58 11.02 6' 59 30.0 179 30.0 23.66 8.98 1 10 53 55.6 176 00.0E 25.55 95 64 58.2 169 58.6 23.85 13 62 11.0 17951.0 21.87 10.12 76 65 58.0 169 35.0 22.18 61 67 20.0 169 45.0 21.58 11.41 86 65 56.3 169 22.9 20.86 10.72 87 65 24.3 17021.7 22.83 6 59 30.0 179 30.0 23.99 8.17 60 67 15.7 170 49.6 21.12 13.50 61 67 18.0 170 00.3 21.07 70 66 55.0 169 55.0 20.75 8.42 182 TABLE 1 - continued Samples collected from the Akademik Korolcv in 1988. TAXA STATION LAT. LONG. 6"C 5'-^N °N °W (-"/,.! ) ("/,., ) Euphausiid 87 65 24.5 170 21.5 19.64 8.54 Euphausiid 67 66 56.0 165 50.0 20.95 9.18 Euphausiid 86 65 56.3 169 22.9 20.32 6.55 Euphausiid 64 67 17.8 166 42.6 20.92 8.62 Euphausiid 93 64 58.2 169 58.6 21.11 8.99 Euphausiid 88 65 21.6 169 59.3 21.50 8.94 Euphausiid 98 64 43.5 171 11.0 22.44 12.28 Euphausiid 85 65 50.0 169 10.0 21.03 8.95 Euphausiid 22 63 00.4 176 00.1 20.46 10.94 Euphausiid 50 68 39.7 168 20.0 21.09 9.58 Euphausiid 6 59 30.0 179 30.0 21.52 8.09 Euphausiid 104 63 50.7 169 12.3 22.65 8.64 Euphausiid 55 67 44.1 168 26.4 19.63 9.04 Euphausiid 61 67 20.0 169 45.0 20.18 9.26 Euphausiid 99 64 32.0 17001.0 20. 1 3 10.87 Euphausiid 13 62 11.0 17951.0 21.53 10.84 Euphausiid 73 66 44.0 171 05.0 20.06 9.44 Euphausiid 42 63 55.2 172 04.4 8.12 Euphausiid 25 64 00.0 179 20.0 18.71 8.43 Euphausiid 107 64 23.0 171 39.0 21.97 Euphausiid 110 53 55.6 176 00.0E 23.41 Euphausiid Large 27 64 43.3 177 48.2 8.83 Euphausiid Large 11 61 35.0 178 39.0 20.63 9.51 Euphausiid Large 6 59 30.0 179 30.0 21.88 8.78 Euphausiid Large 50 68 39.7 168 20.0 21.00 Euphausiid Large 20 62 34.7 175 03.5 21.94 13.50 Euphausiid Small 11 61 35.0 178 39.0 20.74 10.77 Euphausiid Small 32 64 00.0 175 00.0 19.91 8.97 Euphausiid Small 76 65 58.0 169 35.0 21.57 8.64 Euphausiid Small 40 64 08.0 172 30.0 20.21 9.41 Euphausiid Small 38 63 55.0 173 35.0 20.77 8.28 Euphausiid Small 27 64 43.3 177 48.2 17.73 7.81 Phytoplankton 71 66 44.0 171 05.0 20.52 5.92 Phytoplankton 24 63 42.6 178 28.8 19.01 7.17 Phytoplankton 44 67 24.1 173 21.7 21.69 9.56 Phytoplankton 76 65 58.0 169 35.0 19.96 5.85 Phytoplankton 55 67 44.1 168 26.4 18.71 7.22 Phytoplankton 59 67 09.2 172 59.8 22.48 Phytoplankton 45 67 44.0 172 50.0 21.90 6.39 Phytoplankton 76 65 58.0 169 35.0 25.01 11,55 Phytoplankton 20 62 34.7 175 03.5 24.12 1 1 .80 Hippolytid Larvae 55 67 44.1 168 26.4 19.04 9.54 Hippolytid Larvae 42 63 55.2 172 04.4 20.54 Pandalid Larvae 50 68 39.7 168 20.0 19.93 1 L21 Decapod Larvae 86 65 56.3 169 22.9 19.96 8.65 183 5.2.5 Zooneuston YUVENALY P. ZAITSEV, LEONID N. POLISCHUK. and BORIS G. ALEXANDROV Department of Hydrobiology of Active Surfaces of the Sea. Institute of Southern Seas, Odessa, USSR Introduction Samples of zooneuston were taken at 33 stations in the Bering Sea and at 14 stations in the Chukchi Sea (see scheme with stations). The equipment for collecting zooneuston samples included a two stage plankton-neuston net FNS-2 and a fish fry trawl MNT (Zaitsev, 1971). A synchronous hauling of the upper two microhorizons, the neuston layer (0-5 cm) and the subneuston layer (5-25 cm) was performed. The MNT is a high speed equipment device for collecting hydrobiological material (rate of trawling up to 3 m/sec) in the 0-25 cm layer. The PNS-2 was hauled at a distance of several tens of meters at a velocity of 25 cm/sec. The volume of filtered water was determined taking into consideration the time of filtration and speed, as well as the working area of the net. Ninety-four samples altogether were taken in the Bering and Chukchi Seas. 47 samples each from the neuston layer and the subneuston layers (Table 1). TABLE 1 Zooneuston samples taken in the Bering and Chukchi Seas. Chukchi Sea Berina Sea Region Chirikov Gulf Gulf of Polygon Anadyr East Polygon South Amount of Stas. Samples 14 28 8 16 14 3 28 10 6 12 The aiea of sampling embraced a large water mass including the south part of the Chukchi Sea, Chirikov Gulf, and Gulf of Anadyr of the Bering Sea, as well as the oceanographic East and South Polygons. The most northerly station was situated at a latitude of 68°39'7"N, the most southerly, 57°25'7"N. Thus the study of zooneuston was carried out in the near polar and far polar waters. As a result of the interaction of the ocean and atmosphere on the ocean-atmosphere boundary, certain specific conditions of life are created. One of the contours of the biotopes 6f the halosphere is found here. The neuston population has much species diversity and in the abundance of organisms, and plays an important part not only in the life of the water layer, but in the sea bottom, especially in the shelf zone (Zaitsev, 1971). The study of neuston in high latitude sea watens — in this case, the Bering and Chukchi Seas — is important from many points of view. First of all, the neuston of extreme north as well as extreme south seas has not been studied. Secondly, the Bering and Chukchi Seas are known as background regions of the World Ocean (Tsyban et ai, 1985), and thus neuston from these waters will most certainly react to it (Zaitsev, 1986). The first preliminary investigations of zooneuston in the Bering Seas were carried out in the summer of 1 962 ( Chebanov, 1965; Zaitsev, 1971). A more profound study of neuston was performed by L. N. Polishchuk and B. G. Alexandrov under the guidance of Yu. P. Zaitsev in July 1984. The same authors studied zooneuston from 28 July to 31 August 1988 during the Third Joint US-USSR Bering & Chukchi Seas Expedition on board the research vessel (RA') Akademik Korolev. This was the first time neuston was studied in the waters of the Chukchi Sea. The animal population of the Bering and Chukchi Seas differs in species composition and high density of populations (Tables 2,3). It should be noted that because of specific natural conditions in those seas, such as low temperatures, ice fomiation, lengthy winter season, etc., only temporary forms of zooneuston developed that were capable of terminating their ontogenesis during the short period of hydrological summer. First of all, these include the larvae of bottom invertebrates (bivalves, gastropods, cirripeds, polychaetes, echinoderms, phoronides. nemertines). decapod larvae, euphausiid larvae, juvenile fornis of chaetoghaths, as well as early stages (eggs, nauplii, copepodites ), the majority of copepods, the cladocerean Evadne nordmanni , the pelagic polychaete Tomopteris pacifica, pteropods (Clione limacina, Limacina helicina). tunicates (Fritillaria borealis, Oikapleura labradoriensis). hydrozoans (Taghkea octopunctata, Aglantha digitate, Obelia sp., Pantaehogon haeckeli). and the siphonophore Dimophyes arctica. Adult copepods such as Oncea borealis, Tortanus discaudatus, Eurytemora pacifica. Acartia longiremis, and Pseudocalanus minutus behaved like neustophils. The most northern representative of the pontellid family Epilabidocera amphitrites proved to be a typical neuston. The average number of organisms in the neuston layer in the East Polygon amounted to 1 18,284 specimens/m', which is about 4.5 times greater than the amount discovered here in the summer of 1984. It is not difficult to give the reason for this significant difference. As to the ratio of the abundance of organisms in the neuston and subneuston layers, in 80% of the cases, there were more in the former layer (Table 4). Tintinnids, pteropods, nauplius eggs and, early copepodite stages of Copepoda (Ointhona siniilis, Acartia longiremis. Pseudocalanus minutus, Eucalanus hungii). decapod larvae, and juvenile polychaetes prevailed in the neuston layer. 184 TABLE 2 Qualitative composition of zooneuston of the Bering and Chukchi Seas in the period July 28-August 29, 1988. Bering Sea Chukchi Taxa Anadyr Ch irikov Eastern Southern Sea Gulf Gu If Region Region Protozoa Globigerina sp. - + + + + Tintinnoinea + + + + + Rotatoria Synchaeta sp. + + - - + Coelenterata Hydroidea Aglantlia digiUile + + + + + Ralhkea octopunctata + + - - + Ohelia sp. - - - - + Paniaehogon haeckeli - - + - - Scyphozoa Cyan eel sp. - + - - - Siphonophora Dimophyes arctica + - - - + Polychaeta Tomopteris pacifica + - - - - Polychaeta, larvae + + + + + Pteropoda Limacina helicina + + + + - Cllone limacina + - + + + Bivalvia, larvae + + - + + Gastropoda, larvae - + - - + Cirripedia Balanii, larvae + + - - + Lepas,}uv. - - - + - Nemertini, larvae - - - + - Ophiura, larvae + + - + + Echinoidea, larvae + + - - - Asteroidea, larvae - + - - - Phoronidea. larvae - + - - - Bryozoa. larvae - + - - - Copepoda Ointhona similis + + + + + Acaitia longireinis + + + + + Pseiulocalunus elongatus (=nunutus) + + + + + Calanus glacialis + + - + + Calanus plumclmis + + + + + Eucalunus hungii + + + + + Eiiiytemoni Iwrdmuni + - - + Euiytemora pacifica - + - - + Oncea borcalis - + - - + Ceniropages mcmurrichi - + - - + Torlaniis Jiscuudutus - + - - + EpiUihidocera amphitiites + + - - + Harpacticoida sp. + + + + + 185 TABLE 2 - continued Qualitative composition of zooneuston of the Bering and Chukchi Seas in the period 28 July-29 August 1988. Berii ig Sea Chukchi Taxa Anadyr Chirikov Eastern Southern Sea Gulf Gulf Region Region Cladoccra Evadne nordmaimi - + - + + Podon Iciickartii - + - - + Amphipoda Panithemisto japonica + + + - + Hyperiidae - + + + + Decapoda Brachiura ova, larvae + Euphausiacea, larvae + Chaetognatha Sagitta elegans + Tunicata Oikopleuni lahradoriensis + Fritillciriu horecdis + Pisces, ova, larvae + + + + + + + + + + + + TABLE 3 Average abundance (speciniens/ni') of organisms in the neuston (0-5 cm) and subneuston (5-23 cm) layers of the Chukchi and Bering Seas in the period of July 28- August 29. 1988. • Sea. Neuston Subneuston region layer layer Chukchi Sea 43.464 19.775 Bering Sea Polygon East 118.235 48.314 Polygon South + Station 113 56,749 53.244 Gulf of Anadyr 17,238 20,083 Chirikov Gulf 75,321 55,669 Average of the Bering Sea 67.240 44.340 The hydrozoan Pantaehogon liaeckeli. polychaete larvae, and nauplii of Eiiccdamis hitngii were encountered only in the neuston layer. As in the summer of 1984. copepods dominated in the neuston layer making up 93'7f of total abundance. In density of organisms in the neuston layer, this area leads among others investigated in the Bering and Chukchi Seas. In South Polygon, the hydrozoans Aglantha digiiale, larvae of bivalves, ophiurians, eggs, copepodites and adult Pseudocalaims ininutus. eggs of decapoda, and tunicates of Oikopleura and Fritillaria were found in the sample. Neuston Subneuston layer layer 225.295 109.432 134,079 68,397 30,772 45,810 47,273 16,692 53,764 2,240 118,234 48,314 TABLE 4 Abundance of organisms (specimens/m') in the neuston and subneuston layers in the Polygon East of the Bering Sea July 28-31, 1988. Station Number 2 3 4 5 Average V. copepodites of Calamis plumchnis. W-Calanus glacialis and. Evadne nordnuinni of Cladocera and also juvenile Lepas show complete adherence to the neuston layer. Thirty-three percent more organisms prevail in the neuston layer (Table 5). Average abundance in the region was 6,749 specimens/m', which is 1.6 times greater than in the summer of 1984. In comparison to other marine aquatories at that time, this region was characterized by high abundance indices. In 1988, according to quantitative characteristics, it ranks third after East Polygon and Chirikov Gulf. As copepods were the dominating group up to 80%, with hyperiids ( 1 7.6%) ranking second. The rotatorian Synchaeta. 186 TABLK 5 TABLE 6 Neuston Subneuston layer layer 51,761 57,414 143.692 71,539 74,810 43,278 33.035 80,063 3.972 18,811 61.454 54,221 33.226 48,664 56.749 53,294 Abundance of organisms (specimens/ni') in the neuston and subneuston layers in Polygon South and Station 1 13 (south region) in the Bering Sea, August 26-29, 1988. Station Number 108 109 110 111 112 Average for polygon 113 Average for region hydrozoan Agkmtha digitale, pteropods Limacina and Clioue, larvae of bivalves, cirripeds, and ophiuinans. all adult stages of Acartia tumida, nauplii. first three copepodite stages of Pseiidocahinus ininutus, nauplii. IV-V copepodite stages and adult Calanus glacialis, IV-V copepodite stages of Epilahidocera amphitrites, nauplii oi Acartia longiremis and Eucalanus biingii, hyperiids Paratheinisto japonica, zoea of decapods and tunicate Oikopleura all predominate in the neuston layer of the Gulf of Anadyr. Absolutely predominating in the neuston layer were tintinnids. the pelagic polychaete Tomopiehs, larvae of Bryozoa, nauplii of Calanus plumchrus and Epilahidocera amphitrites, and larvae ( megalopa) of decapods. In comparison to the subneuston layer. 36*^ more organisms predominated in the neuston layer. Average abundance in the region was 17,238 specimens/m' (Table 6) which is almost 7 times less than in the east and 3.2 times less than in the south. Copepods dominated in the Gulf of Anadyr similar to above-mentioned polygons, making up about 91%. In this region, a large amount of detritus formed from dying phytoplankton cells was found in zooneuston samples. A large amount of organic matter suspended near the pelagic surface layer possibly inhibited the development of neuston and was one of the reasons for low indices. As to the Chirikov Gulf, foraminiferous. tintinnids. all stages of ontogenesis of Oncea horealis, l-III stages of copepodites of Calanus glacialis, and adult forms of Tortanus and Epilahidocera were encountered only in the neuston layer. Similar to other regions of the Bering Sea. copepods (40% ) prevailed in Chirikov Bay; however, here there were significantly more zoobenthos larvae, especially the bivalves (20%) and marine urchins (23%). The average number of organisms in the neuston layer of Chirikov Gulf was 75.321 specimens/m\ which ranks second after the East Polygon in the Bering waters studied (Table 7). The most northern water mass studied is the Chukchi Sea. which has a quite diverse and abundant zooneuston. The rotatorian Synchaeta, the hydrozoans Rathkea, Obelia, Aglantlia, polychaete larvae, the pteropod Clione, larvae of bivalves, cirripeds. ophiurans. and marine urchins, all stages of ontogenesis of the copepods Aca/V/t/ longiremis, Pseudocalanus Abundance (specimens/m') of organisms in the neuston and subneuston layers of the Gulf of Anadyr of Bering Sea August 1-8, 1988. Station Number Neuston laver Subneuston layer 6 76,393 80.984 7 9,259 16.335 9 3,680 5.564 11 8,748 13.053 13 43,274 54.790 15 12,023 13.133 18 5,551 4,943 19 6,164 3.948 22 18.263 1 2.598 24 11,061 2.192 32 22,541 22.335 35 2,330 10,418 36 4.119 2.372 41 17.916 39,399 Average for region 17.238 20.083 TABLE 7 Abundance of organisms (specimens/m') in the neuston and subneuston layers of Chirikov Gulf in the Bering Sea, August 19-23, 1988. Station Neuston Subneuston Number layer layer 83 24,246 44.624 86 24,529 15.850 89 82,185 42,832 92 269.147 73.910 100 110.104 46.180 102 30.241 174.919 104 60.120 45.317 Average 75.321 55.669 minutus, Eutytemora pad flea, Eurytemora herdmani, Oithona similis, eggs and nauplii of Calanus glacialis, nauplii of Eucalanus hungii, nauplii and copepodite stages of Acartia f(//?!/V/fl.furcilliaofeuphausiids.megalops of decapods, juvenile polychaetes. and tunicates Oikopleura and Fritillaria quantitatively predominated in the neuston layer. Foraminiferous. the siphonophore Dimophyes arctica, gastropod larvae. I-IIl copepodite stages of Eucalanus pacifica, nauplii of Epilahidocera amihitrites, III-V copepodites of Calanus plumchrus, hyperiids. eggs, and larvae of fish were found in greater quantities in the neuston layer. In 86% of the cases, there were more organisms predominating in the neuston layer (Table 8). Average abundance for hydrobionts in the 0-5 cm layers was 43.464 specimens/m'. which is 1.5 times less than the average abundance of organisms in this biotope of the Bering Sea. 187 TABLE 8 Abundance of organisms (speciniens/m') in tiie neuston and subneuston layers of the Chuicchi Sea. 9-15 August 1988. Station Neuston Subneuston Number layer layer 45 7.522 3.300 47 67,608 21.875 49 24.767 14.447 50 45.612 28.940 52 19.139 12.120 53 51,158 14.806 55 25.198 9.522 59 19.854 9.435 61 55.572 30,052 64 64.568 24.263 66 162.169 59.902 71 44.039 26.134 74 3.626 3.887 75 17.659 18,172 Average for Sea 43.464 19.775 Similar to the Chirikov Gulf in the Bering Sea, the Chukchi Sea was dominated by copepods, bivalve larvae, and tunicates making up 50%, 26%, and 17%. coirespondingly. from the total number of organisms. Besides, protozoa, rotatoria, hydrozoans, polychaete larvae, cirripeds, ophiurians, marine urchins, cladocereans. euphausiids. decapod larvae, fish eggs, and larvae were encountered. Thus, the number of organisms in the neuston layer in comparison to the subneuston layer in the Bering Sea (East Polygon, 80%; South Polygon, 33%; Gulf of Anadyr, 38%; Chirikov Gulf, 75%) prevailed on the average in 63% of the cases; in the Chukchi Sea, 86%. The distribution of the number of organisms in the neuston and subneuston layers of the Bering and Chukchi Seas is illustrated in Fig. 1. Taking into consideration the dominance of organisms (%) in these two layers, seven regions less favorable for the development of neuston in comparison to others have been distinguished (Fig. 2). It is known that wind and surface water circulation have a great influence on the development and distribution of neuston. According to the general scheme of surface water circulation in the Bering and Chukchi Seas, the regions pertain to zones of mixing of waters of different origin, such as: I-II — warm Pacific and Bering marine waters; III-IV — warm Pacific and cold fresh Anadyr waters; V — cold fresh Anadyr and cold Chukchi marine waters; VI — warm Pacific and Bristol waters; and VII — warm Pacific and cold Chukchi marine waters. The data received, at first glance, do not coincide with Zaitsev's concept (1977), where it has been stated that a rich community of neuston develops on the boundaries between different water masses. Probably, the main factor here is the velocity of water currents. At small velocities a concentration of organisms occurs, initiating the development of hydrobionts; CHUKCHI PENINSULA «^^^ o^ o 3.23-3.68 O 3.69-4 15 () 4 16-4 60 C) 4,61-5 08 O 5.09-5.55 Concentration (%) in Neuston layer (0-5 cm). SubNueston I, LgN.no'm Fig. 1 . Distribution of organisms in the near surface microlayers and relation to abundance in stations in the Bering and Chukchi Seas. at greater speeds, organic matter promoting their development is carried out with the currents. The following explanation may also hold. The regions do not coincide with the areas of convergence of heterogeneous waters but with the centers of circulation of surface currents where funnels are formed and organisms are sucked into them entering the lower layers of the pelagic zone. This explanation, probably, is closer to the truth, as the regions with a higher density of organisms in the neuston layer (Fig. 3), when compared to regions unfavorable for the development of zooneuston. confimi that they are adjacent to one another, but the former overlap with marginal regions of circulation of surface currents. Five areas of distribution of organisms in the neuston layer of the Bering and Chukchi Seas having high abundance are distinguished: southwest of the southern region (South Polygon), southeast of the eastern region (East Polygon), the northwest of the Gulf of Anadyr, the north and east of Chirikov Gulf, and the east and north of the Chukchi Sea. The average abundance of organisms in the neuston layer of the Bering Sea is 68,658 specimens/m', and 43,464 specimens/m' in the Chukchi Sea. The most diverse in number was the eastern region in the Bering Sea ( East Polygon ), 1 18,234 specimens/m\ while the lowest numbers were found in the Gulf of Anadyr, 17,238/m\ Fig. 2. Areas ot absence ( 1 ) and presence (2 ) of aggregations olorganisms in the neuston layer. Isoline marks the boundary of equal distribution of organisms in the near surface microhorizons. On characterizing the qualitative composition of zooneuston represented by 47 taxa, it should be noted that the greatest species diversity was found in the Chukchi Sea and Chirikov Gulf (up to 38 taxa). The smallest amount of species (18) was discovered in East Polygon. The dominating group of organisms in all regions investigated in the Bering and Chukchi Seas was made up of copepods (Fig. 4). Among the 14 species of copepods. a significant part was played by three: Oithona similis, Acartia longireniis. and Pseudocalamts niinutiis. During the summer of 1 984, a similar pattern was observed, but the number of cold- loving Pseudocakmus organisms was more abundant than Acartiadht neritic, epipelagic species). But this was due to the slight heating of surface waters in comparison to that during the period of investigation. In the neuston layer, the copepods were represented by all stages of development, while the ratio of different age groups according to regions was about the same. More than half of the number of copepods pertained to earlier stages of ontogenesis (eggs, nauplii), which gives evidence for their high reproductive activity corresponding to the biological summer period. The wide shelf in the northeast part of the Bering Sea and slight depths in the Chukchi Sea maintain favorable conditions for the existence of bottom fauna with bivalve mollusks, echinoderms, polychaetes, etc., predominating. Their larvae CHUKCHI PENINSULA Fig. 3. Abundance ( Ig number/m") of zooneuston in regions investigated in the Bering and Chukchi Seas. 1^ 3.4; 2—3.4-3.6; 3—3.6-3.8; 4— 3.8-4.0; 5—4.0^.2; 6—4.2^.4; 7-^.4-^.6; 8—4.6-4.8; 9—4.8-5.0; 10— > 5.0. make up a significant part of the total number of zooneuston in the Chirikov Gulf (larvae of marine urchins, 24%; bivalve mollusks, 20%; and polychaetes, 29%). In comparing the Chukchi Sea to Chirikov Gulf, the role of bottom invertebrate was slightly less; they make up to 30% (larvae of bivalve mollusks, 26%; cirripeds, 3%; and ophiurans, 1 %). In the rest of the regions of the Bering Sea, the role of sea bottom larvae is insignificant. Even in East Polygon which is partly located in the neritic zone over small depths, they are represented by polychaetes making up only tenths of a fraction of specimens/m'. Probably, larvae from these regions are carried out by currents flowing from the south to the north and northwest. Thus, on the average, copepods in the neuston layer of the Bering Sea made up 77%; larvae of bottom invertebrates, 12%; hyperiids, 4%; tunicates, 3%; and shell infusorians, 2%. Many taxa are common for the fauna of zooneuston of the regions investigated. When using the method of Preston ( 1962), it has been established that the fauna of zooneuston of the Chukchi Sea and Chirikov Gulf are identical. The index (coefficient) of differences is minimum, while the high similarity index gives evidence, first, to similar conditions of existence, and second, to the exchange of fauna between these regions (Table 9). 189 CHUKCHI PENINSULA o« ppi^ I I Amphipoda I j Copepoda liii-ilj Tunicata ^B Larvae* I I Yana • Polychaeta+Gaslropoda+Bivalvia+Ciffipedia+Ophiura+Echinoidea +Asteroidea+Decapoda+Foromdea Fig. 4. Ratio between average abundance and qualitative composition ot zooneuston in investigated regions of the Bering and Chukchi Seas. TABLE 9 Coefficients of faunistic similarity and differences of zooneuston of the Bering and Chukchi Seas (according to materials collected during the summer. 1988). Sea, region 1 2 3 4 5 Similarity ■ # Chukchi Sea 0.69 0.80 0.43 0.55 Bering Sea Gulf of Anadyr 0.31 0.53 0.46 0.40 Chirikov Gulf 0.20 0.48 0.55 0.41 Eastern region (East Polygon) 0.57 0.55 0.45 0.62 Southern region (South Polygon) 0.45 0.77 0,59 0.38 Differences The indices of faunistic similarity in the other regions are high, which shows that their fauna are partly or completely isolated. The exchange of species is insignificant or there is none, while conditions forexistence of zooneuston aredifferent. In the Bering Sea, distribution of zooplankton can be divided into five faunistic groups (Vinogradov, 1956;Brodsky, 1957); south Bering Sea, north Bering Sea, east and west neritic, as well as, deep-water Bering Sea. After confirming, with the help of literature data ( Mescheryakova, 1 970; Motoda & Minoda, 1974; Kolosova et ai. 1987), the composition of indicator species characterizing the first four groups, an analysis was carried out of their distribution in the neuston layers of the Bering and Chukchi Seas (Fig. 5). The center of south Bering Sea faunistic group was situated over the deep water part of the south and east regions of the Bering Sea, and in the way of two tongue-like intrusions entered into the Gulf of Anadyr. The center of the north Bering Sea is broken in the area. One part is found south of the Gulf of Anadyr, another in the central and northeastern part of the Chukchi Sea. The center of the west neritic group is situated in the Chirikov Gulf and Chukchi Sea. One south Bering Sea faunistic group is characteristic for the south and east regions of the Bering Sea. The main part of the east neretic and faunistic group is located in the northeast of the CHUKCHI PENINSULA li* * Bering ^'4 s ft? . <■>. Q? Sea '¥• ^ ^ o^ m A B C D .Scheme of distrihulion (6()'/i and more dominating) ol Bering Sea faunistic groups in the neuston layer of the Bering and Chukchi Seas; A - south, B - north. C - west neritic, D - east neritic groups. 190 Chirikov Gulf, and through the Bering Strait near Alaskan shores enters the Chukchi Sea. The second part is found in the central region of the Chukchi Sea. Thus, there is a mixing of three faunistic groups in the Chukchi Sea (east, west neritic. and north Bering Sea). In the Chirikov Gulf (Bering Sea), a mi.ving of two faunistic groups occurs (east and west neritic). and in the Gulf of Anadyr, three (west neritic, north, and south Bering Sea). The conclusions obtained from the similarity of neuston fauna in the areas investigated according to Preston's methods (Preston, 1962) were confirmed in detail by biogeographic analysis based on quantitative as well as qualitative data. The mosaic distribution of Bering Sea faunistic groups in the neuston layer of the Chukchi Sea confirm the coinplex hydrodynamics of near surface waters and their connection with the Bering Sea. 191 Subchapter 5.3: Icthyoplankton 5.3.1 Larval Fish Distribution TINA WYLLIE ECHEVERRIA and C. PETER McROY Institute of Marine Science. University of Alaska at Fairbanks. Fairbanks. Alaska. USA Introduction Zooplankton samples are routinely taken during Shelf Transfer and Recycling Project (ISHTAR) cruises. Larval fish occurred incidentally in the samples. We decided to identify the fish and investigate the abundance and distribution of species. These results are part of the Third Joint US-USSR Bering & Chukchi Seas Expedition aboard the RA' Akademik Korolev from 27 July to 2 September 1988. Materials and Methods Ichthyoplankton were collected along with zooplankton in a 1 -m circular net with 505 jam mesh. A vertical tow was made through the water column at 40 m/min. All larval fish were identified to family. Species were identified and standard length (SL) measured using vernier calipers for the Gadidae and the Pleuronectidae. teleost families containing commercially utilized species. The depth the larval fish occupied cannot be determined from this sampling technique. Coachman and Shigaev (Subchapter 2.1, this volume) delineate three principal water masses in the northern Bering and Chukchi Seas. For the purposes of this study we are interestedin two of these water masses: /. water originating in the deep southern Bering Sea that travels in the Bering Slope Current into the Gulf of Anadyr then north through Bering Strait, herein referred to as Anadyr stream water (ASW); and 2. water that resides on the eastern central shelf of the Bering Sea characterized by lower salinity than ASW, herein referred to as Bering Shelf water ( BS W ). We delineated these two water masses further by the presence of certain zooplankton species. Indicator species for BSW are Thysanoessa raschii, Calanus marsluillae. and Calanus glacialis. Indicator species for AS W are: Thysanoessa inermis. Neocalanus cristatus. Neocalanus plumchrus. and Metridia spp. Water masses were defined in order to e.xplore the possibility of passive transport of fish larvae into or through the study area. Chlorophyll a concentrations, as measured by fluorescence (Parsons et a!.. 1984), were detennined for each station (see Robie et ai. Subchapter 5.1.2, this volume), integrating the concentrations from discrete depths for surface to bottom or to 50 m when depths were >50 m. Results and Discussion Seven families: Scorpaenidae (rockfishes), Liparididae (snailfishes), Ammodytidae (sandlance), Cottidae (sculpins), Stichaeidae (pricklebacks), Gadidae (codfishes), and Pleuronectidae (flatfishes) were present. Three species of Gadidae — Theragra chalcograinnia (walleye pollock). Boreogadus saida (arctic cod), and Eleginus gracilis (saffron cod) — were identified and two species of Pleuronectidae — Hippoglossoides elassodon (tlathead sole) and Limanda sp. (yellowfin sole) (Table 1 ) (Matarese et ai, 1989). TABLE 1 Larval fishes sampled from the northern Bering and Chukchi Seas, the number of stations where each family or species was collected, the total number of each family or species in the samples, and the percent of each family and species of the total number offish sampled during the cruise. Taxa Stations Larvae % Total (N) (N) Liparididae 18 25 14 Ammodytidae 3 3 -) Cottidae 1 1 <1 Stichaeidae 2 2 1 Scorpaenidae 1 1 <1 Gadidae Theragra chalcogramma 26 68 40 Boreogadus saida 3 5 3 Eleginus gracilis 3 3 2 Pleuronectidae Hippoglossoides elassodon 14 56 32 Limanda sp. 2 8 5 TOTALS 58 172 100% Fish larvae were found in 58 of the 90 stations sampled (Frontispiece). Abundance ranged from 1 to 29 fish per station (Fig. 1). Fishoccurthroughoutthestudy area, primarily along the eastern border to the Gulf of Anadyr, in waters characterized as both ASW and BSW. Larval fish may be associated with a particular water mass, but we cannot detemiine this because we did not take discrete depth samples. The association of larval fish relative to phytoplankton fields as measured by chlorophyll a concentrations can only be discussed generally. Integrated data for each station shows an association of larval fish with chlorophyll values less than 100 mg/m'. Theragra chalacogranuna was the most abundant and widespread of the identified species (Fig. 2). They were concentrated where BSW overlay AS W ( Fig. 4 ), with associated chlorophyll values below 100 mg/m- (Fig. 3). Two size classes, newly hatched larvae (4—7 mm SL) and larvae 20-25 mm SL dominated the samples (Fig. 5). The larvae occurred northward of known spawning grounds and north of where known adult concentrations occur (NOAA, 1987). 195 I I I I I I — I I I I I I I — I \ \ \ \ \ I \ I Chukchi Sea Fig. I. Abundance and distribution of ichlhyoplanl^ton during August 1988. Fig. 3. Concentration ot chlorophyll (mg/nr ) integrated throughout the water column (from Robie et al.. Subchapter 5.1.2, this volume). Larvae of T. chalcogramma occur where chlorophyll concentrations are 10) in the area of our highest concentrations (Fig. 2) (Sobolebskiy el al., 1989). Concentrations of pollock larvae in the Gulf of Anadyr can be explained by advection of eggs and larvae from known spawning areas. Pollock larvae in the Chukchi Sea occurred in ASW suggesting advection from the south. However, spawning grounds that support the advection of larvae into the Gulf of Anadyr are too far south to be a source of larvae in the Chukchi Sea. The speed ofthe Bering Slope Current is lOcm/s (Kinder et al., 1975; Khen, 1989). Using daily growth rates for larval pollock from the Gulf of Alaska (Yoklavich & Bailey, 1989), 5-7 mm SL larvae are approximately 4-5 days old. Adding the developmental rates for the pelagic eggs of 14 days, these larvae could be in the current for approximately 20 days. At average transport rates of 8.64 km/day, the larvae could cover 173 km. They would not reach the farthest stations where larvae were caught (Stations 47, 50, 69, 89, and 94; .see Frontispiece), located from 300-600 km from grounds where spawning is reported to occur in July and August (Hinckley, 1987). 196 Water masses defined hy zooplankton Theragra Chalcogramma 180° 1750 LONGITUDE 170° 165° Fig. 4. Dislributionof Anadyr and Bering Shelf water masses. Water masses were delineated by the species of /.ooplankton present in samples from 94 stations. Larvae of T chalcogramma occur where shelf waters overlie oceanic waters. The larger size range of larvae arc approximately 35 days old. If we add the incubation time for eggs of 14 days, these larvae could have been transported 740 km, placing them in our study area. The original spawning stock for these fish could be the continental slope area northwest of the Pribilof Islands, where spawning takes place as late as October (Hinckley, 1987). Two additional gadids, B. saida and E. gracilis, occurred in the Chirikov basin and Chukchi Sea where BSW overlay ASW, associated with chlorophyll values of 200-600 mg/m-. Two size modes were present, newly hatched larvae (5 mm SL) and larger larvae (20 mm SL). Both species occur within the known spawning areas and the area of adult distributions (NOAA, 1987). The flatfishes area represented principally by two species. Hippoglossoides elassodon concentrate at the eastern edge of the Gulf of Anadyr where BSW overiay ASW associated with relatively low integrated chlorophyll values (1 00 mg/m-). The samples are dominated by new hatched larvae (5 mm SL) and a few larger larvae ( 1 5 mm SL). The newly hatched larvae are 5 10 15 20 LENGTH (mm Standard length) Fig. 5. Size frequency histogram of T. chalcogramnui larvae. Two size groups occur, new hatched larvae (4-7 mm SL) and older larvae (20-25 mm SL). present north of reported spawning grounds and much later in the season than major spawning ( winter-spring)(NOAA, 1987). Again either larval transport into the area in Anadyr waters and/or a later more northerly spawning population can account for the presence of these larvae . Limanda sp. is probably the yellowfin sole, L. aspera. Positive identification could not be made due to the occurrence of L. prohoscidea in the study area, for which there is not larval description. Limanda sp. occurs in the Chukchi Sea in middle shelf water associated with relatively low chlorophyll values. Larvae range from 5 to 15 mm SL and occur in known spawning areas and during the spawning season. Conclusions 7. Larval tlsh susceptible to capture in a 1-m, bridled plankton net were primarily commercially important species. Walleye pollock (40% of the total larval fish) and flathead sole (38% of the total larval fish) were dominant species. This study is a preliminary evaluation of the species composition and distribution of larval fishes. The number of larval fish underestimates the abundance due to patchy distributions and the potential ability of larval fish to avoid the net we used. 2. The presence of larvae in the study area could be accounted for in most cases by known spawning stocks of the species in the area or by advective transport from known spawning regions. However, for 7". chalcogramma and H. elassodon, some of the newly hatched larvae were far north of known spawning areas, suggesting the possibility of as yet unknown spawning stocks. 3. The results indicate a distribution of larval fishes that warrants further investigation with the appropriate gear, sampling both larval and adult populations. We plan to investigate the possibility of a northern population of spawning walleye pollock in the area north of St. Lawrence Island. 197 Subchapter 5.4: Modeling 5.4.1 Complex Ecological Evaluation of Planktonic Communities of the Pelagic Zone ALLA V. TSYBAN, ANDREY S. KULIKOV, MIKHAEL N. KORSAK, VASSILIY M. KUDRYATSEV, and VLADIMIR M. VENTSEL Institute of Global Climate and Ecology. State Committee for Hydrotneteorology and Academy of Sciences, Moscow, USSR Introduction Population-biocenotic effects of anthropogenic impacts of the marine environment, the detection of which is necessary to characterize the ecosystem stability level, are reflected in the structural and functional characteristics of its communities. However, natural communities also can cause the reconstruction of the processes of the functioning and structure of the ecosystem biotic component. At the current level of knowledge in this field, it is difficult to distinguish between the results of anthropogenic impact and natural variability. It is only possible to solve this problem in the course of long-term observations on the basis of data on the background levels of the structural and functional characteristics (Izrael & Tsyban, 1989). Structural characteristics include evaluation of the species composition, numbers, and biomass of different systematic dimensional and trophic groups, as well as spatial and temporal variability of these parameters. Functional characteristics include the energy flux through communities, which are formed at the expense of productive and destructive processes, as well as trophic relations between the components of communities. A great body of data characterizing the structure and functional processes of the basic elements of plankton communities was determined on comprehensive ecological expeditions in the Bering Sea ( Izrael & Tsyban, 1990) organized by the Natural Environment and Climate Monitoring Laboratory in June 1981 and jointly with American specialists in 1984. These data have formed the basis for estimation of the integral characteristics of the status of the plankton communities inhabiting the epipelagic in the Bering Sea, carried out on the basis of the analysis of trophic relations between their elements. Calculations of the parameters of the production-destruction processes of zooplankton present an important stage in this work. Materials and Methods Our work is based on the data obtained during the comprehensive ecological investigations carried out during the expedition in the Bering Sea on board the RA^ Akademik Shirshov in June 1 98 1 and RA' Akademik Korolev in July 1 984 on the South, East, and West Polygons (Fig. I ). During the investigations, the basic structural characteristics of the plankton inhabiting the surface 100-m layer (numbers and biomass of bacterioplankton; species composition, number, and biomass of phyto-, microzoo-, and mesozooplankton) and functional ones (primary and bacterial production) were detennined. Results of the analysis of the data characterizing the status of individual dimensional-trophic groups of the Bering Sea plankton community and the description of the methods used in investigations have been published in the monographs (Izrael & Tsyban, 1987) and some papers (Moisyev, 1987). The ration and production of the heterotrophic link of plankton communities was calculated in accordance with a scheme developed in the plankton laboratory of the P. P. Shirshov Oceanology Institute of the USSR Academy of Sciences ( Vinogradov (feShushkina, 1987). The authors believe this to be the only acceptable method for determining the production values of heterotrophic elements of multispecies plankton communities in the ocean pelagic region, consisting of populations with an extended period of reproduction and functioning in conditions of limited food resources. The preparations of data for the calculations consisted, first, in separating out the elements of the communities with allowance for taxonomic, dimensional, and trophic particularities of the biota. Analysis of the trophic composition of zooplankton and communities, as a whole, was carried out using the literature data describing food interrelations in the epipelagic zones of subarctic and highly productive regions of the World Ocean (Petipa, 1981; Cooney & Coyle, 1982; Vinogradov & Shushkina, 1987). The results of the analysis made it possible to isolate nine basic elements in the Bering Sea plankton (Table 1 ) and evaluate the relations between them from the degree of the use of different kinds of food by various consumers (Table 2). The scheme of trophic relations includes, apart from the elements, dead organic matter (d+y ) that resulted from the vital activity of hydrobionts and could be consumed by them again. The feeding selectivity coefficient J assumed the values 1.0, 0.5, 0.2. and 0, which corresponded to the following gradations: "consume fully," "consume partially," "consume little," and "do not consume at all" (Vinogradov & Shushkina, 1987). In the case when all organisms making up the consumer element ( i ) are able to consume all the organisms making up the prey element (j). the coefficient was given the maximum value of 1 .0. The ability of one consumer to use a variety of the objects making up the prey elements for food, J was given the value 0.5 or 0.2. If there is no trophic relationship between the elements, J = 0. 201 65 Fig. I. Scheme of location ot the polygons in iho Bering Sea in June 1981 and July 1984. Group TABLE 1 Elements of the plankton community, their composition and characteristics. Caloric content, cal/mg wet Element A""!" Assimllability weight Composition of elements Phytoplankton (p) Small (< I.S m), (p,) Large (> I-") m). IpO Bacterioplankton (b) Zooplankton (z) Microzooplankton (a) Zooflagellates (a,) Infusorians (a,) Mesozooplankton (m) Fine nannophage filters (0 Small euryphages (v) (0.3-3.0 mm) Large euryphages (g) (3.0-30.0 mm) Predators (s) 1.0 0.6 0.5 1.0 1.0 0.6 0.7 1.0 0.6 0.7 0.8 0.6 0.7 0.7 0.5 0.7 0.7 0.35 0.5 0.7 1.0 0.5 0.7 0.7 0.35 0.4 0.05 Copepod nauplii, copepodite stages of fine calanoid genera Microcalaiius. PseudocaUiiuis. Acurua. larvae of mollusks, polychaetes, echinoderms; rotifers, appendicularians Younger copepodite of calanoid genera Calanus. Eiicalanus. older copepodites of calanoid genera Aciirtia. Pseiuloccilaniis. cyclopods, harpaclicoids, ostracods Nonpredatory pteropod mollusks Older copepodites of calanoid genera Catamis Eucalainis. Euphausia Decapod larvae, sideswimmers, nemertines, polychaetes Predatory pteropods Arrowworms Siphonophorcs, medusae, ctenopores 202 TABLE 2 Scheme of trophic relations and nutrition selectivity coefficient (J). Consumer- Prey ' - element element b ^1 a. f V P, P: d+y* b 0 0 0 0 0 0 0 1.0 a, 1.0 0 0 0 0 0 0 1.0 32 1.0 1 .0 0.2 0 0 1.0 0.2 0.5 f 0.5 1.0 0.5 0 0 1.0 0.5 0.2 V 0.2 0.5 0.5 0.2 0.2 0.5 1.0 0.2 g 0 0 0.2 0,5 0.2 0.5 1.0 0.2 s 0 0 0.2 0.5 0.5 0 0 0 * d+y- detritus suspend ed(d); ind dissolved (y). The supposition that the overall ration of each element of the community [C(i)| consists of its particular rations [r,,,,] on different food objects was used as the basis for the quantitative assessment of the trophic relations (Vinogradov & Shushkina, 1987). The particular ration r,,,, of the i-th consumer on the j-th prey element with the biomass B,j| was calculated by the modified V.S. Ivlev's equation (Shushkina et ai. 1984); r,„-r,7[l-exp(-^„B,„)/E,„l (1) where E,,, is consumption of the j-th element by all its users; Since the value E,,, had not been known at the moment of the calculation by the iteration method: first, the maximum tension with respect to the j-th feed, K„ = Ir,7/B„„ (2) and an underrated approximate value r,,,, were calculated. Then E|j =Zr|,j| was found and substituted into Equation ( 1 ) to obtain a new value r„j|, etc., up to satisfying the equality: E,pZr,„=Zr-r[l-exp(-^„B„)/E,J (3) The value of the maximum particular ration r,™" was calculated by the relation: C ^B,J, 2:b,j„ (4) The maximum overall ration C""' was determined by the balance equation (Vinbeig & Anisimov, 1966): C:-"^ = |P,"'-HR,] U, (5) where R is the metabolic rate of the i-th element 1/U, — the assimilability coefficient of the i-th element; and P""* — the maximum possible value of production of the i-th element was calculated by the formula: ,^ __ K?,"' "' ~ ' l-KT,- (6) where K?;-" — coefficientofthe expenditure of food assimilated by the i-th element in growth. The full real ration of each i-th consumer [C, ] was calculated as a sum of particular real rations: C = I r, (7) and production of the i-th element, expect phytoplankton, as: P, = C,„U;'-R, (8) All the dimensional and trophic elements were characterized by the definite numbers N, average weight W. and biomass B. Energy value of biomass was expressed in calories on the basis of caloric content values K. It is known that its average values for copepodite plankton are equal to 0.7-0.8 cal/mg wet weight (Vinogradov & Shushkina, 1987). At the same time, the caloric content of interzonal species of Copepoda and Euphausiacea, playing an important role in the trophic chain of the Bering Sea, increased at the expense of fat inclusions up to 1 .0-1 .5 cal/mg wet weight (Shushkina, 1977). The bodies of an overwhelming majority of these Crustacea, found in the samples during the present investigations, contained droplets of fat. In this connection, the caloric content value of large euryphages was assumed equal to 1 .0 cal/mg wet weight. The values of the coefficient of the use of consumed food in growth, in maximum meeting food requirements of consumers K( 2i max), and food assimmilability 1/U(i ) of each element are presented in Table 1. M. E. Vinogradov and E. A. Shushkina (1987) believe that one may use in the calculations the values of K(2 max) equal to 0.5-0.6 for elements including small animals that quickly reproduce themselves: bacteria, protozoans, and fine nannophage filters; and 0.4—0.5 for hydrobionts whose size exceeds 1 .0 mm. Assimilability was assumed as a value independent of the concentration of consumed objects — it was established equal, on average, to 0.6 for plant food and 0.7 for animal food (Sushchenya, 1975). It should be noted that Japanese researchers (Ikeda & Motoda, 1978) and American ones (Dagg et ai, 1982) used the value of the assimilability equal to 0.7 for calculations of production of the herbivorous plankton of the Bering Sea. The respiration rate of zooplankton was estimated with the use of the general dependence of the metabolic rate R on the weight of the body W at a water temperature of up to 20 grad, which was obtained experimentally (Shushkina el ai. 1984; Vinogradov & Shushkina, 1987): R = 0.6W"« (9) where R is measured in mcal/organism/day, and W in meal/organisms. A correction for temperature allowing for Q( 10)=2.2 was introduced into the values of the metabolic rate. The respiration expenditure of the bacterioplankton and zooflagellates was determined by other methods. The calculation for the bacterioplankton was carried out with allowance for the production measured during the investigations and the efficiency of the use of assimilated food in growth, determined experimentally (Sorokin & Mamaeva, 1980): K(2)=0.33. The value of R/W for zooflagellates was assumed equal to 250%. It remained constant in all the calculations (Shushkina t-rrt/.. 1984). At the productive stage of the development of plankton communities, the main course of energy is the production of photosynthesis, produced during the day under consideration. At the same time, some elements of the community are able to use the energy of autochthonous dead organic matter formed inside the community for a day and allochthonous dead organic matter introduced from outside or formed earlier, prior to the period of observations. Inclusion of dead organic matter, especially its dissolved fornis, into the trophic chain of a community occurs mainly through bacterioplankton. At the destructive stage of the development of acommunity, a situation may arise when the energy of autochthonous dead organic matter will not be sufficient to cover the ration of bacterioplankton. In this case, an element of self-regulation is introduced, according to the calculation scheme (Shushkina 203 etai, 1984; Vinogradov &Shushkina, 1987) — that is, bacteria consume, besides autochthonous organic matter, as much allochthonous organic matter as they need to meet their requirements for food in conditions of production of this element, determined experimentally, and in order that the production calculated on the above scheme corresponded to that determined experimentally (Shushkina era/., 1984b). Itis assumed that allochthonous organic matter consumed by other elements of the community is far less than that consumed by bacterioplankton, and it is not taken into account in the calculation scheme. The method makes it possible not only to estimate the net production of the community [P(0)] equal to the difference between the primary production formed at the entrance into the system [P(p)] and the heterotrophic destruction of the community D^, = Z R,, but also to estimate the actual production of the conmiunity, P^,,, which takes into account at the beginning the primary production and allochthonous organic matter arriving to the trophic chain the bacterial link: P„ , = P„+rbx-D,. (10) where r(bx) is the ration of allochthonous organic matter. There following tropho-ecological characteristics of the elements and community as a whole (Vinogradov & Shushkina, 1987) are used in the work: — the degree of the satisfaction of requirements in food of the consumer element (i): S, = c/c,"'''' (ID — real specific production of the prey element (j): ^' B, (12) where 2x0 = 1 day: and the ratio of the energy assimilated by bacterioplankton and other detritophages to the total energy of detritus energy and phytoplankton assimilated by all the heterotrophic parts of the community: i A,(d+y) P =1 — '^ s (13) • §,A,(d+y)4.Z A, As a criterion for determining the trophic character of waters, use was made of the ratio of the primary production level to the overall heterotrophic destruction level [Kjp = Pp / D„] according to the following ranges of the coefficient values: K(3p) > 2, hypertrophic; 2 > K(3p) > 0.7 eutrophic; and 0.7 > K(3p). oligotrophic water (Lebedeva, etal., 1982; Vinogradov & Shushkina, 1983). Results The values of the structural and functional characteristics of the plankton community found m the epipeiagic region of the southwestern Bering Sea at South and East Polygons consisted of 719^ mesozooplankton hydrobionts; the portions of other dimensional and functional groups accounted for 10% each. The results obtained have indicated that the community under consideration was at the destructive stage of the seasonal development and experienced a deficiency of newly formed organic matter. The amount of energy necessary to maintain the vital activity of heterotrophic elements lD(o)] was nearly four times more than the energy arriving to the community as a result of photosynthesis of phytoplankton [P(p)], which determined respectively the negative values of the net production of the community [P(o)]. Its average level was -1 1.8 kcal/m- day. The average values of the coefficient of the primary production of the community [K(3p)] made it possible to place the waters of the study areas into the category of mesotrophic waters. It should be noted that 74% of the values of the overall heterotrophic destruction consisted of the respiration expenditure by bacterioplankton. Energy of allochthonous organic matter arriving to the community though the bacterial link fully covered a shortage of the production of autotrophs. As a result, the actual production levels of the community [P(act)] had positive values and amounted to an average of 4.9 kcal/m- day. Functioning of the zooplankton elements of the community, in such a situation, was based to a great extent on the detrital food chain. The amount of the energy of dead organic matter assimilated by heterotrophic accounted, on average, for 53% of the total volume of the energy (p) assimilated by heterotrophs. Only 29% of the total ration of zooplankton consisted of phytoplankton. The basis objects of its food were the following heterotrophic elements: bacterioplankton (24%) and small zooplankton (37% ). The existence of the communities under conditions of a deficiency of newly formed organic matter caused a certain tension in the trophic relations, which was reflected in a comparatively low degree of satisfaction of the food requirements of zooplankton (5): 73%, on average, for infusorians and 81% for mesozooplankton, as well as in the negative values of the rates of real production (t, ) of micro- and mesozooplankton. This indicates a tendency for an increase in biomass of these elements. Unlike the polygons located in the southwestern deep- water region of the Bering Sea, the North Polygon was characterized by the status of the plankton communities in two kinds of water masses of different origin and having different hydrological indices, namely, the waters of the central shelf (the central and south areas of the polygon) and the waters of the Anadyr Current (the north area of the polygon) (Izrael & Tsyban, 1990). In this connection, the structural and functional characteristics of the plankton communities discovered in the region of the North Polygon differ greatly from those calculated for the community of the epipeiagic regions of deep-water areas of the Bering Sea and were different inside the polygon; the characteristics of its north region differed appreciably from those in its southern part (Table 3). In the waters of the Anadyr Current (the northern part of the North Polygon ), the community was at the clearly expressed production stage of succession. Its total biomass [B(o)] was maximum over the whole w ater area of the sea and amounted to an average of 61.3 kcal/m-. The biomass of phytoplankton makes up more than two-thirds of this volume; the remaining part consisting of mesozooplankton content of the pelagic region was not significant. The production of phytoplankton was almost four times more than the overall magnitude of destruction of organic matter. The magnitude of production of the community [P(o)J 204 TABLE 3 Structural and functional characteristics of the plankton community of the Bering Sea in July 1984. Elements of POLYGONS the plankton (i.j) South East West North Characteristics Northern part Southern part 1 ■> 3 4 5 6 7 B„. kcal/m- 41.3 ±7.3 37.9 ±6.6 51.0± 1.2 61.3 ±3.9 28.8 ±3.2 B/B„, % P 6±2 12 ±5 11 ±4 69 ±2 69 ±2 b 8±2 12±4 3 ± 0.5 2 + 0.3 9±3 a 14±6 12±2 9± 1 2 ±0.5 6±1 ni 72 ±7 64 ± 10 77 ±4 27 ± 1 17±2 D,„ kcal/m- 9.0 ± 1.7 17.7± 1.8 23.8 ± 3.3 10.8 ±0.4 11.4± 1.7 R/D„. % b 59+ 10 80 ±2 82 ±2 90 + 2 91 ±2 a 24 ±9 9± 1 8±2 3± 1 6±2 m 17±4 11 ±2 10± 1 7± 1 3± 1 Pp/D,, 0.33 ±0.1 3 0.22 ±0.08 0.27 ±0.06 3.90 ± 0.46 0.65+0.18 P„. kcal/m- day -7.1 ±2.6 -13.1 ±2.1 -15.1 ±2.1 30.1 ±3.2 -5.3 ± 2.3 P,,,, kcal/nr 0.7 ± 1 .3 6. 1 ± 3.4 7.9 ±0.1 44.1 ±3.0 7.3 ± 1.2 p, % 62 ±3 61 ±7 36 ±6 11 ± 1 30 ±9 E/C,. % P 24 ±6 23 ±4 40 ±9 94 ±1 78 ±7 b 28 ±2 27 ±3 16±2 2± 1 14 ±6 z 37 + 5 37 ± 5 38 ±6 4± 1 5± 1 d+y 11±2 13 ±2 6± 1 0 3± 1 6,% a 75 ±4 72 + 4 71 ±4 100 98 ± 1 m 82 ±2 80 + 2 82 ±3 100 99 ± 1 ^ P 0.62 ±0.51 2.58 ± 2.37 0.34 ±0.1 9 1.07 ±0.29 0.12 + 0.07 b 0.11 ±0.34 2.27 ± 0.65 5.27 ± 1.77 4.99 ± 1.28 3.13 + 0.94 a -0.12 ±0.09 -0.16 ±0.09 -0.17±0.10 0.36 ±0.03 0.38 ±0.01 m -0.13 ±0.05 -0.13 ±0.05 -0.12 ±0.06 0.08 ±0.01 0.10±0.01 reached the average value equal to 30 kcal/m- day, which made it possible to classify the waters of the studied area as hypertrophic waters. The degree of satisfaction of the food requirements of consumers (8) was maximum, which was indicative of the absolute availability of food. Ninety-four percent of their total ration consisted of phytoplankton; the detrital component was practically absent [E(i)/C(z)|. The average value of the index (p), through which the role of detritus in the total volume of energy assimilated by heterotrophs, was estimated and accounted for only 11%. Consequently, the food chain of the plankton community was realized more completely in the waters of the Anadyr Current as compared to other studied areas. In the waters of the central shelf region (the southern part of the North Polygon) the level of the overall biomass of the plankton community [B(o)l was very low and did not exceed 30 kcal/m'. This value was two times less than that in the waters of the Anadyr Current. While the fraction of phytoplankton remained constant in spite of the absolute reduction of the biomass of autotrophs by half, the mesozooplankton content decreased by 10%, and its biomass became three times less, and the role of bacterio- and microzooplankton increased to 9% and 6%, respectively. The productivity of waters in the region underconsideration was low and corresponded to the mesotrophic level. The relation between the rates of the primary production and overall heterotrophic destruction pointed to the predominance of the process of destruction of organic matter over photosynthesis in the same proportion as in the deep-water southwestern region of the sea. A deficiency of the consumed organic autochthonous matter [P(o)] reached 5.3 kcal/m- day. but it was covered in plenty at the expensive of allochthonous organic matter [P(act)]. Judging by the low production rate of phytoplankton (P/B = 0.25/day), the cells of algae were in an inactive state. It is felt that the major fraction of phytoplankton biomass arrived to this region from the water area of the Anadyr Current where plankton was characterized by the maximum possible production and by accumulation of the autotrophs due to the horizontal mixing of water mass. Due to the low productivity of the shelf waters, the trophic relations inside the plankton community were tense. The degree of satisfaction of the nutritional requirements of zooplankton did not reach the maximum level, 98-99%. Apart from phytoplankton ( 78% ), bacterioplankton (14%) and detritus made up the ration of the animals. The energy flux through the detrital chain increased up to 30% (p) as compared to that calculated for the Anadyr Current. In spite of the low productivity of shelf waters, the rate of actual production (^) of all the elements of the community was positive, which pointed to a tendency towards an increase in their biomass. 205 Conclusion The results of the comparative analysis of the status of the plankton communities discovered in June 1981 and July 1984 have shown that the majority of revealed changes constituted a part of the seasonal spring-summer dynamics of the structures and functions of the pelagic communities in the basin under consideration (Geinrikh, 1959; Kun, 1975). At the same time, it is obvious that the revealed differences were determined, to a certain measure, by the interannual variability of the habitats of the communities. At the present stage of investigations, it is not possible to distinguish between them, but we believe that the seasonal variability is a determining factor; therefore, the data obtained were considered in the aspect of the seasonal variability. The structural and functional characteristics of the Bering Sea plankton communities are described in detail in a monograph (Izrael & Tsyban, 1990). Comparing the structure of the community populating the deep-water southwestern Bering Sea in June 1981 and July 1 984, it should be noted that in the changeover from the spring to summer season, the biomass of the whole community decreased, on average, by a factor of 1.5, and, in particular in the East Polygon, by a factor of 2 (Fig. 2). A decrease in the level of the inde.x occurred primarily at the expense of phyto- and bacterioplankton. Their biomass decreased by a factor of 2.6 and 3.0, respectively. The character of changes in the biomass of plankton elements was not similar. Thus, at the West Polygon where the epipelagic community was, due to the geographic location, at an earlier stage of the seasonal development as compared with other sea areas (Kulikov, 1989), the biomass of microzooplankton increased by a factor of 1.7 and that of mesozooplankton, by a factor of 1.2. At the same time, a significant decrease of the mesozooplankton biomass (on average, by a factor of 1.7) was observed at South and East Polygons. As a result of the seasonal reconstruction of the structure of the community, the fraction of autotrophs reduced in July by a factor of 2 and that of zooplankton, vice versa, increased by a factor of 1 .2 in all the investigated areas of the deep-water region of the Bering Sea. In the shelf region of the northern Bering Sea, the trend of the seasonal succession in the north sharply differed from that in the south. In the south of the North Polygon, the dynamics of the structure of the shelf pelagic community had the same features as that in the deep-water regions (see Fig. 2). In contrast, in the northern area of that polygon, in the waters of the Anadyr Current, the biomass of the community increased by a factor of 1 .5. This was determined by an increase in the biomass of phytoplankton by a factor of 1.6 and in that of mesozooplankton by a factor of 2.3. The relative values of the biomass of these elements changed in the same direction, but to a lesser extent. At the same time, the fraction of the biomass of microheterotrophic elements decreased, on average, by a factor of 3-5. The character of the functions of the plankton communities in the surface waters of the Bering Sea also underwent a B,,, Kcal/m- 70 - :::-;,^OT IMS I 1984 Wesi l^tSl WS4 East 14X1 ms4 years South Polygons phvio- plankion ^/^^' ^j'^^;' ^^'^u baclerio- planklon microzoo- plankton mesozoo- plankton 1981 1984 Northern part 1981 1984 years, areas, polygon Southern part Fig. 2. Biomass of the plankton coniiniinities (B,,) and consisting elements (B)mJune 14X1 and July 1984. number of significant changes in July 1984 as compared to June 1981. For instance, the levels ofthe overall heterotrophic destruction of organic matter in the southwestern sea (South, East, and West Polygons) increased by a factor of 2-5 and at North Polygon by a factor of 6. So sharp an increase in the rate of destruction in July was caused by a significant increase by a factor of 6- 13 in the intensity of vital activity of the bacterial link of the epipelagic communities. The fraction of bacterial destruction in the total flu.x reached, on average, 90% in July 1984 versus 43% in June 1981. As a result of increased expenditure ofthe communities on metabolism in the summer period, the balance of production- destruction processes observed in spring was disturbed in the epipelagic region of the deep-water sea areas and shelf water masses (Fig. 3). A deficiency of newly formed organic matter [P(o)] in these regions amounted to an average of 1 2 kcal/m- day. Attention is drawn to the fact that in spring the inflow of the energy of allochthonous organic matter to the community was small and did not produce a significant effect on the levels of the actual production |P(act)|, and in summer its volume sharply increased and covered in plenty a shortage of organic matter produced in the community. Thus, for instance, at the West Polygon, in the most productive waters among those investigated in the deep-water sea area, the average value of the actual production of the community reached in June and July 1 . 1 kcal/m- day and 7.9 kcal/m- day, 206 Kcal/m^ day ^:^ ^^ n ^71 Fig. 3. Net (P„l and actual V{^J production of the plankton communities in June 1981 and July 1984. respectively. In the waters of the Anadyr Current, the level of the net production in summer increased as compared with spring values by a factor of 1 .5 and that of the actual production by a factor of two. Intensification ofdestruction in summer adversely affected the efficiency of production of the autotrophic link (Fig. 4). After the changeover of the community populating the epipelagic region of the southwestern deep-water area of the Bering Sea from the spring status to the summer one, the levels of the index K(3p) decreased by a factor of two to five, which is indicative of a decline in the trophic character of water, from the eutrophic levelinJune 1981 tothemesotrophiconeinJuly 1984. In shelf water masses, no changes in the level of trophicity occurred, since an increase in the destruction was compensated by an increase in primary production. In the waters of the Anadyr Current, in spite of an increase in the values of the coefficient on average by a factor of three, they remained at a high level, which characterizes the waters of this region as hypertrophic. It should be noted that during both the spring and summer seasons of the investigations, the energy tlux through the detrital food chain played an important role primarily in the functions of the plankton community populating the epipelagic region of the deep-water area of the Bering Sea (Fig. 5 ). The levels of the values of p, which characterized the energy fraction of assimilated dead organic matter in the total volume of the energy assimilated by heterotrophic elements, were maximum at later stages of seasonal development of the community (at the South and East Polygons). The trend of the seasonal succession of the Bering Sea plankton communities, accompanied by a change in the structure June 1981 July 1984 -boundary of levels of trophit uhiiiatler of Soutfiem Nonhem North Polygons, pans are^s Fig. 4. Efficiency of production Pp/D„ of the plankton communities in June 1981 and July 1 984. P^,- production ofphytoplankton;D„- heterotrophic destruction of the community. Net 40 Production 30 20 to 0 ~~x July 1984 Polygons, parts Soulhem Northern part ^ North 1 Fig. 5. Relations between level of energy assimilated by bacteria and other detritophages and level of energy of dead organic matter and phytoplankton assimilated by all heterotrophs of the plankton communities in June 1981 and July 1984. and parameters of the processes of functioning, also included a reconstruction of trophic interrelations between the elements of the communities in the quantitative respect. A decrease in the supplies of "primary food" in the epipelagic region of the deep-water in the summer season has led to intensification of preying of euryphages on others (Fig. 6). The fraction of animal food became predominant in the overall ration, of zooplankton elements in contrast to their spring ration, in which vegetable food predominated. A contrary tendency was observed at the North Polygon where the fraction of phytoplankton in the ration of zooplankton increased in a changeover to the summer season. In conditions of a summer deficiency of easily assimilated food, observed in the southwestern Bering Sea, the degree of meeting nutritional requirements (5) of micro- and mesozooplankton decreased appreciably as compared with the levels calculated for the spring season (Fig. 7). The real specific production of these elements {t,) acquired negative values, which was indicative of the appearance of a tendency towards a decrease in their biomass (Fig. 8). At the same time, trophic tension appeared in June in the elements of phyto- and bacterioplankton and, vice versa, disappeared in July, and it became possible for the elements to increase their biomass. 207 EfCzoo 1c 70- 60- 50 40 30- 20- 10- 0 1 90 80 70 60 50- 40 ^ ^ ^ Polygons, parts South North West Southern Northern 1 — North —I Polygons, pans 100 90- 80- 70- B — .— - — '^^ 90 June 1981 --K'' 8U 70 July 1984 South East Southern Northern L — North ' Polygons, pans Polygons, parts Fig. 7. The degree of satisfaction of the nutritional requirements of macrozooplankton (A) and mesozooplankton (B) in June 1981 and July 1984. ED ED ^ phyto- baclerio- iooplanklon Fig. 6. Composition of the ration of zooplankton (E/C,^^): A. June 1981; B. in July 1984. Phyloplanklon (p) polygons, areas 5.0 4.0 3.0 2.0 1.0 0 -1.0 Bactenoplankton (b) ,• 1984 — 4 polygons, areas 1981 0.4 0.3 0.2 0.1 0 -0.1- -0.2- Microzooplankton (a) -« 1984 1981 polygons, areas 0.2 0 1 0 -0.1 -0.2 Mesozooplankton (m) «1984 -»1981 ~^ polygons, areas Fig. 8. Realspecificproductionofelements(^,)of theplanktoncommunities(June 1981 andjuly 1984). 208 Chapter 5 References Alton, M. S.( 1974). Bering Sea benthos as a food resource for demersal fish populations. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelley, eds.), pp. 257-277. University of Alaska. Fairbanks. Amone. R. A.. Bidigare, R. R., Trees, C. C. & Brooks, J. M. ( 1 986 ). Comparison of the attenuation of spectral irradiance and phytoplankton pigments within frontal regions. SPIE Proceedings 637, 126-130. Banahan, S. & Goering, J. J. (1986). The production of biogenic silica and its accumulation on the southeastern Bering Sea Shelf. Cont. Shelf Res. 5( 1-2), 199-213. Beklemishev, K. V. ( 1969). Ecology and Biogeography of the Pelagial. Nauka Publishers, Moscow. 291 pp. (in Russian) Bidigare. R. R. ( 1989). Photosynthetic pigment composition of the brown tide alga: Unique chlorophyll and carotenoid derivatives. In Coastal andEstuarine Studies (E. M. Cosper, V. M. Bricelj & E. J. Carpenter, eds.), 35, 57-75. Springer- Verlag, Berlin. Brodsky, K. A. ( 1957). Fauna of copepods (Calanoida) and Zoogeographical Distribution in the Northern Part of the Pacific Ocean and Adjacent Waters. M. L. Izdatelstov Akademia Nauk, USSR, 222 pp. (in Russian) Chebanov, S. M. (1965). Distribution of Hyperiids in the Near-Surface Layer of the Southern Part of the Bering Sea and Adjacent Regions of the Pacific Ocean. Trudy VNIRO, 58, 85-91. (in Russian) Chislenko, L. L. (1968). Nomograms for Determining the Weight of Aquatic Organisms from Body Size and Shape. Nauka Publishers, Leningrad, 105 pp. (in Russian) Coachman, L. K. (1986). Advection and mixing on the Bering-Chukchi shelves. ISHTAR Progress Report 1986, pp. University of Alaska, Fairbanks. Coachman, L. K. (1990). The Bering Sea ecosystem: Basic characteristics and prospects for further studies. In Study of the Bering Sea Ecosystem. No. 2, pp. 20-27. ( Yu. A. Izrael & A. V. Tsyban, eds.). Gidrometeoizdat Publishers, Leningrad, (in Russian) Coachman, L. K., Aagaard, K. & Tripp. R. B. (1975). Bering Strait: The Regional Oceanography. University of Washington Press, Seattle, Washington, 172 pp. Coachman, L. K. & Shigaev, V. V. ( 1992). Northern Bering- Chukchi Sea ecosystem: The physical basis. (Subchapter 2.1, this volume). Cooney. R. T. & Coyle. K. O. (1982). Trophic implication of cross-shelf copepod distribution in the southeastern Bering Sea. Mar. Biol. 70(2), 187-196. Crippen, R. W. & Perrier, J. L. ( 1974). The use of neutral red and Evans blue for live-dead determination of marine plankton. Stain Technology 49,97-104. Dagg, J. J., Vidal. J.. Whitledge. T. E.. Iverson. R. & Goering. J. J. The feeding respiration and excretion of zooplankton in the Bering Sea during a spring bloom. Deep Sea Res. 29(1 A). 45-63. DeNiro. M. J. & Epstein. S. (1978). Influence of diet on the distribution of carbon isotope in animals. Geochim. Cosmochim. Acta 42. 495-506. Fleming, J. M.&Couchman, J.( 1978). Preservation of vitally stained zooplankton for live-dead sorting. Estuaries 1(2), 135-137. Fry, B. & Sherr, E. ( 1984). "C measurements as indicators of carbon flow in marine and freshwater ecosystems. Mar. Sci. 11, 13-47. Gabrilovich, A. B. ( 1976). A unit for complex measurements of characteristics of light scattering media. 28 pp. Institute of Physics, Belonissian Academy of Science, Minsk, (in Russian) Geinrikh, A. K. (1959). Biological seasons in the Bering Sea plankton and horizontal distribution of zooplankton biomass. Trudy Oceanography Institute AN SSSR 30, 107-114. (in Russian) Gieskes, W. W. C. & Kraay, G. W. (1983a). Unknown chlorophyll a derivatives in the North Sea and tropical Atlantic Ocean revealed by HPLC analysis. Lininol. Oceanogr. 28, 757-766. Gieskes, W. W. C. & Kraay, G. W. (1983b). Dominance of Cryptophyceae during the phytoplankton spring bloom in the central North Sea detected by HPLC analysis of pigments. Mar. Biol. 75, 179-185. Grebmeier, J. M. & McRoy. C. P. (1989). Pelagic-henthic coupling on the shelf of the northern Bering and Chukchi Seas. III. Benthic food supply and carbon cycling. Mar. Ecol. Prog. Ser. 53,79-91. Grebmeier, J. M.. McRoy, C. P. & Feder, H. M. (1988). Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. I. Food supply source and benthic biomass. Mar. Ecol. Prog. Ser. 48, 57-67. Grinbart, S. B, Stakhovskii, N. 1.. Vinnikova. M. A.. Gurtubaev. M. M. & Solovieva, O. A. (1976). Anthropogenic effect on the biocenoses of Odessa Bay and their protection. Third Conference of the All-Union Hydrohiological Society iRigd. 11-16 May 1976). Thesis report, Zinatne, Riga. Ch. 1, pp. 143-148. (in Russian) Hansen, D. A., Goering, J. J., Walsh. J. J., McRoy. C. P.. Coachman. L. K. & Whitledge. T. E. (1989). Summer phytoplankton production and transport along the shelf break in the Bering Sea. Cont. Shelf Res. 9, 1085-1104. Haryu, T. (1980). Larval distribution of walleye pollock, Theragra chalcogramma, in the Bering Sea, with special reference to morphological changes. Bull. Fac. Fish. Hokkaido Univ. 31(2), 121-136. Hinckley, S. (1987). The reproductive biology of walleye pollock, Theragra chalcogramma, in the Bering Sea. with reference to spawning stock structure. Fish. Bull. (US) 85. 481-499. 209 Holmes. R. W. (1958). Surface chlorophyll a, primary production and zooplankton volumes in the eastern Pacific Ocean. Cons. Perm. Int. E.xplor. Mer. 144. 109-116. Hood, D. W. & Kelley, E. J. (1974). Introduction. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelley, eds.), pp. xv-xxi. University of Alaska, Fairbanks. Ikeda, T. & Motoda, S. ( 1978). Zooplankton production in the Bering Sea calculated from 1956-1970. Mar. Sci. Comm. 4(4), 329-346. (in Russian) Ivanov, A. P. ( 1975). Fundamentals ofHydrooptics. 102 pp. Nauka Publishers, Minsk, (in Russian) Iverson, R. L., Coachman. L. K., Cooney. R. T., English, T. S., Goering, J. J., Hunt, G. L., Macauley, M. C, McRoy, C. P., Reeburgh, W. S. & Whitledge, T. E. (1979). Ecological significance of fronts in the southeastern Bering Sea. In Ecological Processes in Coastal and Marine Systems (R. J. Livingston, ed.), pp. 437^66. Plenum Press, New York. Izrael, Yu. A. (ed. ) (1 983 ). Study of the Bering Sea Ecosystem. Gidrometeoizdat Publishers, Leningrad, 1 57 pp. ( in Russian) Izrael, Yu. A. & Tsyban, A. V. (eds.) ( 1987). Comprehensive Analysis of the Bering Sea Eco.fystem. Gidrometeoizdat Publishers, Leningrad, 264 pp. (in Russian) Izrael, Yu. A. & Tsyban A. V. ( 1 989). Anthropogenic Ecology of the Ocean. Gidrometeoizdat Publishers, Leningrad, 528 pp. (in Russian) Izrael, Yu. A. & Tsyban, AV. (eds.) (1990). Ecosystem Investigations of the Bering Sea. No. 2. Gidrometeoizdat Publishers, Leningrad, 344 pp. (in Russian) Izrael, Yu. A., Tsyban, A. V., Kazakov, Yu. E, McLanin, D. D. A., Putz, P. E.. Alexander, D. E. & Brown, M, ( 1983). Study of the Bering Sea Ecosystem. Gidrometeoizdat Publishers, Leningrad, 157 pp. (in Russian) Jeffrey, S. W. ( 1974). Profiles of photosynthetic pigments in the ocean using thin-layer chromatography. Mar. Biol. 26, 101-110. Jones, R. J., Ludlow, M. M., Troughton. J. H. & Blunt, C. G. ( 1981 ). Changes in the natural carbon isotope ratios of the hair from steers fed diets of C4, C3, and C4 species in sequence. Search 12, 85-87. Kawamura,T.( 1963). Preliminary survey of primary production in the northern Pacific Ocean and Bering Sea, June-August 1960. Inform. Bull. Planktol. Jpn. 10, 28-35. Khen, G. V. ( 1 989). Oceanographic conditions and Bering Sea biological productivity. In Proceedings of an International Symposium in Biological Management of Walleye Pollock (Anchorage, Alaska, 1988), pp. 79-90. Alaska Sea Grant Report No. 89-1, University of Alaska, Fairbanks. Kinder, T. H., Coachman, L. K. & Gait, J. A. (1975). The Bering Slope Current system. J. Phys. Oceanogr. 5, 231-244. Kisselev, J. (1937). Composition and Distribution of Phytoplankton in the Northern Part of the Bering Sea and in the Southern Part of the Chukchi Sea. Tr. Inst. Okeanol. Akad. Nauk, USSR, 25 pp. Koike, I., Furuya, K., Otobe, 0., Nakai, T., Nemoto, T. & Hattori, A. (1982). Horizontal distributions of surface chlorophyll a and nitrogenous nutrients near Bering Strait and Unimak Pass. Deep-Sea Res. 29, 149-155. Kolobova, E. G., Kulikov, A. S. & Kosobokova, K. N. (1987). Mesozooplankton of the Bering Sea. In A Comprehensive Analysis of the Bering Sea Ecosystem {Yu. A. Izrael & A. V. Tsyban, eds.), pp. 141-174. Gidrometeoizdat Publishers, Leningrad, (in Russian) Kopelevich, O. V. (1981). Optical Properties of the Ocean Water. Ph.D. Thesis, University of Moscow, (in Russian) Koval, L. G. ( 1 970a). Elimination of zooplankton in regions of the Black Sea near estuaries. In Protecting Fish Stocks and Increasing the Productivity of the Southern Zone of the USSR. pp. 72-74. ANMSSR Publishers, Kishinev, (in Russian) Koval, L. G. (1970b). The living and dead zooplankton fractions of areas near estuaries and submerged canyons of the Black Sea. In Biological Processes in Marine and Continental Bodies of Water, pp. 1 75- 1 76. Thesis Report of the Second Conference of the AU-Union Hydrobiological Society. ANMSSR Publishers, Kishinev, (in Russian) Koval, L. G. (1978). Consideration of living and dead zooplankton as one of the ways of estimating living conditions. In Proceedings of the Second AU-Union Conference on Shelf Biology (Sevastopol. 24-26 Oct. 1978), Ch. 1, pp. 55-56. Sevastopol, (in Russian) Koval. L. G. ( 1 984). Zoo- and Necrozooplankton of the Black Sea. Naukova dumka, Kiev, 126 pp. (in Russian) KuHkov, A. S. (1989). Age composition of the populations of mass species as an index of the seasonal state of the mesozooplankton community. In Monitoring of the Natural Environment, pp. 88-100. (in Russian) Kulikov, A. S. (1990). Content of dead copepods in the plankton of open regions of the Baltic Sea in May-June 1987. In Study of the Bering Sea Ecosystem, No. 3, pp. 128-135(A.V. Tsyban, ed.). Gidrometeoizdat Publishers, Leningrad, (in Russian) Kulikov, A. S. (in press). Mesozooplankton. In Study of the Bering Sea Ecosystem. No. 2, Gidrometeoizdat Publishers, Leningrad, (in Russian) KumeLsha, A. A. & Vinokurov, V. V. (1984). Analysis of errors involved in detemiination of attenuation index by transmittance meters. 32 pp. Report No. 346, Institute of Physics. Belorussian Academy of Science. Minsk. ( in Russian ) Kun,M.S.( 1975). Zooplankton of Far-East Seas. Pishchevaya Publishers, 150 pp. (in Russian) Lebedeva, L. P., Vinogradova. M. E., Shushkina, E. A. & Sazhin, A. F. ( 1982). Estimate of the rate of the detritus formation process in marine plankton communities. Oceanography 22(4), 652-659. (in Russian) Levin, I. M. (1983). Correlation between white disc transmittance, hydrooptic characteristics and observation conditions. In Optics of the Sea, pp. 92-95. Nauka Publishers, Minsk, (in Russian) Lowry, L. F. & Frost, K. J. (1984). Foods and feeding of bowhead whales in western and northern Alaska. Sci. Rep. Whales Res. Inst. 35, 1-16, Tokyo. Lubny-Herzyg, E. A. (1953). Weight characteristics of the main representatives of the zooplankton of the Okhotsk and Bering Seas. DAN SSSR, 91(4), 949-952. (in Russian) 210 Mamaeva. N. V. (1983). Infusoria of Bering Sea plankton. In Marine Biology. No. 2. (in Russian) Mantoura, R. F. C. & Llewellyn. C. A. (1983). The rapid determination of algal chlorophyll and carotenoid pigments and their breakdown products in natural waters by reverse- phase high-perfonnance liquidchromatography. Anal. Chini. Acta 151. 291-314. Matarese, A. E., Kendall. A. W.. Jr.. Blood, D. M. & Vinter. B. M. (1989). Laboratory guide to early life history stages of Northeast Pacific fishes. NOAA Tech. Rep. NMFS80. 652 pp. Mescheryakova, 1. M. ( 1970). Plankton in the eastern part of the Bering Sea in the spring and autumn hydrological seasons. Trudy VNIRO. v, 70. -Izvestia TINRO, Pischevaya Publishers, Moscow. 72(5), 98-1 14. (in Russian) Moisyev. E. V. (1987). Some regularities of zooflagellate distribution in the Bering Sea. Mar. Biol. (Vladivostok), pp. 30-35. (in Russian) McConnaughey, T. & McRoy. C. P. ( 1 979 ). Food web structure and the fractionation of carbon isotopes in the Bering Sea. Mar. Biol. 53. 257-262. McRoy, C. P., Goering. J. J. & Shiels. W. E. ( 1972). Studies in primary production in the eastern Bering Sea. In Biological Oceanography of the Northern North Pacific Ocean (A. Y.Takenouti.ed.).pp. 199-216. Motoda Commemorative Volume. Idemitsu-shoten. Tokyo. McRoy. P. C, Hood, D. W.. Coachman, L. K.. Walsh. J. J. & Goering, J. J. ( 1986). Processes and resources of the Bering Sea shelf (PROBES): The development and accomplishments of the project. Cont. Shelf Re.s. 5( 1/2)5. Mironov,O.G. ( 1973). Oil Pollution and Marine Life. Naukova dumka, Kiev, 85 pp. (in Russian) Mizutani. H. & Wada. E. ( 1988). Nitrogen and carbon isotope ratios in seabird rookeries and their ecological implications. Ecology 69, 340-349. Motoda, S. & Minoda, T. (1974). Plankton of the Bering Sea. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelly, eds.). pp. 257-277. University of Alaska, Fairbanks. NOAA (1987). Bering. Chukchi, and Beaufort Seas Coasted and OceanZones Strategic Assessment: Data Atlas. Strategic Assess. Branch. Ocean Asses. Div.. Office Oceanogr. Mar. Assess., Natl. Ocean Serv.. N. O. A. A., Rockville, Maryland. Odum. E. (1975). Principles of Ecology. Mir Publishers. Moscow. 650 pp. (in Russian) Parsons, T. R., Malta, Y. & Lalli, C. M. (1984). A Manual of Chemical and Biological Methods for Seawater Analysis. Pergamon Press Ltd.. Elmsford. New York. 173 pp. Pesenko. Yu. A. ( 1 982 ). Principles and Methods of Quantitative Analysis and Faunistic Studies, pp. 119-227. Nauka Publishers, Moscow, (in Russian) Peterson, B. J. & Fry, B. (1987). Stable isotopes in ecosystem studies. Ann. Rev. Ecol. Syst. 18, 293-320. Pctipa. T. S. ( 1 98 1 ). Trophodynamics of copepods in marine plankton communities. Naukova Dumka, Kiev. 255 pp. (in Russian) Preston. F. W. (1962). The canonical distribution of commonness and rarity. Part 2. Ecology 43(N3), 417-420. Robie. W. R.. McRoy. C. P. & Springer, A. (1992). Phytoplankton biomass distribution in the northern Bering Sea and southern Chukchi Sea (Subchapter 5.1.2, this volume). Rundel, P. W.. Ehleringer. J. R. & Nagy, K. A. ( 1989). Stable isotopes in ecological research. Ecol. Stud, Vol. 68. Springer-Verlag, New York, 525 pp. Sambrotto. R. N.. Goering. J. J. & McRoy. C. P. (1984). Large yearly production of phytoplankton in the western Bering Strait. Science 225, 1 147~\ 150. Sambrotto. R. N.. Niebauer. H. J.. Goering, J. J. & Iverson. R. L. (1986). Relationships among vertical mixing, nitrate uptake, and phytoplankton growth during the spring bloom in the southeastern Bering Sea shelf. Cont. Shelf Res. 5(1-2), 161-198. Saupe, S. M., Schell. D. M. & Griffiths. W. (1989). Carbon isotope ratio gradients in western arctic zooplankton. Mar. Biol. 103. 427^32. Sazjin, A. F. ( 1 985 ). The role of detritus and migrating animals in the food supply of the deep-sea fauna of boreal andtropical regions of the Pacific Ocean. Oceanography 25(4), 685-691. (in Russian) Schell. D. M.. Saupe. S. M. & Haubenstock. N. ( 1 987 ). Bowhead whale feeding: Allocation of regional habitat importance based on stable isotope abundances. In Importance of the Eastern Alaskan Beaufort Sea to Feeding Bowhead Whales, 1985-86. (Final Report to US Minerals Management Service.) LGL Ecological Research Associates, MMS 87-0037. Schell, D. M., Saupe, S. M. & Haubenstock, N. (1989a). Natural isotope abundances in bowhead whale {Balaena mysticetus) baleen: markers of aging and habitat usage. Ecol. Stud 68,228-241. Schell, D. M., Saupe, S. M. & Haubenstock. N. (1989b). Bowhead whale (Balaena mysticetus) gmwlh and feeding as estimated by stable isotope abundance techniques. Mar. Biol. 103, 433-443. Schneider. D. C. Hunt. G. L.. Jr. & Harrison. N. M. (1986). Mass and energy transfer to seabirds in the southeastern Bering Sea. Cont. Shelf Re's. 5(1-2). 241-257. Scott. W. (1977). Trace elements in zooplankton particulate products. Nature, p. 269. (in Russian) Sheehan, P. J. ( 1984). Effects on individuals and populations at the ecosystem level. In Effects of pollutants at the ecosystem /fie/. Chapter 4. SCOPE 22. (in Russian) Shushkina. E. A. (1977). Production of zooplankton. In Biological Productivity of the Ocean, pp. 233-247. Nauka Publishers. Moscow, (in Russian) Shushkina, E. A., Vinogradov, M. E.. Lebedeva. L. P. & Umnov. A. A. ( 1 980). Energetics and structural and functional characteristics of the Black Sea plankton communities (autumn 1978). In Pelagic Ecosystems of the Black Sea, pp. 223-243. Nauka Publishers, Moscow, (in Russian) Shushkina, E. A., Vinogradov. M. E.. Vedemicov. V. I., Sukhanova, 1. N. & Tumantseva. N. I. (1984a). Structural and functional analysis of the planktonic communities of the southeastern Pacific Ocean. In Frontal Zones of the Southeastern Pacific Ocean, pp. 257-276. Nauka Publishers, Moscow, (in Russian) 211 Shushkina, E. A., Vinogradov, M. E. & Vostokov. S. B. (1984b). Assessment ofprimary production and heterotrophic destruction in the epipelagic region of the ocean. Oceanography 24, 130-138. (in Russian) Smith. R. C. Bidigare, R. R., Prezelin, B. B., Baker, K. S. & Brooks, J. M. ( 1987). Optical characterization of primary productivity across a coastal front. Mar. Biol. 96, 575-591 . Smith, S. L. & Vidal, J. (1986). Variations in the distribution, abundance, and development of copepods in the southeastern Bering Sea in 1980 and 1981. Cont. Shelf Res. 5(1-2), 215-239. Sobolebskiy, E. I., Shuntov, V. P. & Volkov. A. F. ( 1989). The composition and the present state of pelagic fish communities in the western Bering Sea. In Proceedings of an International Symposium on Biological Management of Walleye Pollock (Anchorage, Alaska, 1988), pp. 523-535. Alaska Sea Grant Report No. 89-1. University of Alaska. Fairbanks. Sorokin, Yu. I. & Mamaeva, T. I. (1980). Bacterial production and destruction of organic matter. In Ecosystems ofPelagium in the Peruvian Region, pp. 104-115. Nauka Publishers, Moscow, (in Russian) Springer, A. M. ( 1988). The Parado.x of Pelagic Food Webs on the Bering-Chukchi Continental Shelf Ph. D. dissertation. University of Alaska, Fairbanks. Springer, A. M., McRoy, C. P. & Turco, K. R. (1989). The paradox of pelagic food webs in the northern Bering Sea. II. Zooplankton communities. Cont. Shelf Res. 9, 359-386. Stepanenko, M. A. ( 1989). The state of stocks and distribution of pollock in the Bering Sea. In Proceedings of an International Symposium on Biological Management Walleye Pollock (Anchorage, Alaska, 1988), pp. 537-547. Alaska Sea Grant Report No. 89-1, University of Alaska, Fairbanks. Stepanov, V. N. & Svetlichnii. L. S. (1978). Nonstationary model of submersion of decomposing zooplankton. Mar. Biol. 47, 55-58. Vladivostok, (m Russian) Stepanova, V. S. ( 1937). Biological indicators of currents in the northern Bering and southern Chukchi Seas. Issledovaniay MoreySSSR 25. 175-213. (in Russian) Sukhovey. V. F. (1986). Seas of the World Ocean. Gidrometeoizdat Publishers, Leningrad, p. 243-247. (in Russian) Sushchenya, L. M. ( 1 975 ). Quantitative regularities of nutrition of the crustaceans. Nauka Publishers, Minsk. 207 pp. (in Russian) Takenouti, A. Y. & Ohtani, K. ( 1974). Currents and water masses in the Bering Sea: A review of Japanese work. In Oceanography of the Bering Sea ( D. W. Hood & E. J. Kelley, eds.), pp. 257-277. University of Alaska, Fairbanks. Taniguchi, A. (1969). Regional variations of surface primary production in the Bering Sea in summer and vertical stability ofwateraffecting the production. Bull. Fac. Fish (Hokkaido Univ.) 20. 169-179. Tieszen, L. L., Boutton T. W.. Tesdahl, K. G. & Slade. N. A. ( 1 983 ). Fractionation and turnover of stable carbon isotopes in animal tissues: Implications for "C analysis of diet. Oceanography 57, 32-37. (in Russian) Timoshenkova, N. P. & Kulikov, A. S. (1988). Methods of selection and processing of zooplankton samples. In Methodological Principles of Comprehensive Ecological Monitoring of the Ocean, pp. 219-229. Gidrometeoizdat Publishers, Moscow, (in Russian) Trees, C. C, Bidigare, R. R. & Brooks, J. M. ( 1986). Distribution of chlorophylls and phaeopigments in the northwestern Atlantic Ocean. / Plankton Re.s. 8, 447-458. Tsyban. A. V.. Korsak, M. N., Volodkovich, Y. L., & MacLaughlin. J. J. A. ( 1985). Ecological investigations in the Bering Sea. In Complex Global Monitoring of the World Ocean. Proceedings of the First International Symposium, Tallinn 2- 1 0 October 1983, v. 1 , Leningrad, Gidrometeoizdat: 40-163. (in Russian) Vinberg, G.G. & Anisimov, S. 1. ( 1966). Mathematical model of an aquatic ecosystem. In Photosynthesizing Systems of High Productivity, pp. 2 1 3-223. Nauka Publishers, Moscow, (in Russian) Vinogradov. A. K. ( 1970). Fish reproduction and oil pollution of the sea. In Proceedings of Second All-Union Scientific Conference on the Problem of Aquatic To.xicology. pp. 25-56. Elm, Baku, (in Russian) Vinogradov, M. E. ( 1956). Distribution of zooplankton in the western regions ofthe Bering Sea. Trudy VGBOl. 173-204. (in Russian) Vinogradov, M. E. & Shushkina, E. A. ( 1983). Succession of marine plankton communities. Oceanography 23, 633-639. (in Russian) Vinogradov, M. E. & Shushkina, E. A. ( 1987). Functioning of the Plankton Communities ofthe Ocean 's Epipelagial. Nauka Publishers, Moscow, 238 pp. (in Russian) Walsh. J. J. & McRoy, C. P. ( 1986). Ecosystem analysis in the southeastern Bering Sea. Cont. Shelf Rese. 5(1-2), 259-288. Walsh, J. J., McRoy, C. P., Coachman, L. K., Goering, J. J., Nihoul. J. J., Whitledge, T. E.. Blackburn. T. H.. Parker. P. L., Wirick, C. D., Shuert, P. G., Grebmeier, J. M., Springer, A. M.. Tripp, R. D., Hansell, D. A., Djenidi, S., Deleersnijder, E., Henricksen, K., Lund. B. A., Andersen, P., Muller- Karger, F. E. & Dean. K. (1989). Carbon and nitrogen cycling within the Bering/Chukchi Seas: Source regions for organic matter effecting AOU demands of the Arctic Ocean. Prog. Oceanogr. 22,279-361. Walsh, J. J., Premuzic, E. T.. Gaffney, J. S., Rowe. G. T., Harbottle. G., Stoenner, R. W., Balsam, W. L., Betzer, P. R. & Macko, S. A. (1985). Organic storage of CO, on the continental slope off the mid-Atlantic bight, the southeastern Bering Sea and the Peru coast. Deep-Sea Res. 32, 853-883. Weikert, H. (1977). Copepod carcasses in the upwelling region south of Cap Blanc. N.W. Africa. Mar. Biol. 42(4), 351-355. Whitledge, T. E., Bidigare, R. R., Zeeman. S. I., Sambrotto, R. N., Roscigno, P. F.. Jensen. P. R., Brooks, J. M., Trees, C. & Veidt. D. M. ( 1988). Biological measurements and related chemical features in Soviet and United States regions ofthe Bering Sea. Cont. Shelf Res. 8, 1299-1319. 212 Yoklavich, M. & Bailey. K. (9189). Growth of larval and juvenile walleye pollock from Shelikof Strait, Gult'oF Alaska, as determined from daily increments in otoliths. In Procecdinfis of an International Symposium on Biological Manaiit-ment Walleye Pollock (Anchorage, Alaska, 1988), pp. 24 1-252. Alaska Sea Grant Report No. 89- 1 , University of Alaska, Fairbanks. Zaitsev, Yu. P. ( 1971 ). Marine Neustonology. Published for NMFS,NOAA. US Department ofCommerce and National Science Foundation, Washington, D.C., 207 pp. (Russian translation). Zaitsev, Yu. P. (1977). Northwestern part of the Black Sea as an object for contemporary hydrobiological investigations. Mar. Biol. 43, 3-7. (m Russian) Zaitsev, Yu. P. (1986). Coneurobionts in ocean monitoring. In Integrated Global Ocean Monitoring. Proceedings of the Finst International Symposium, 2, 79-81. (in Russian) Zenkevitch, L. (1963). Biology of the Sea.s of the USSR. Interscience Publishers, New York. Zhelezinskaya, L. M. (1968). Study of natural mortality of certain organisms of the Black Sea pelagial. In Ecological Biogeography of the Contact Zones of the Sea, pp. 1 35-147. Naukova dumka, Kiev, (in Russian) Zhelezinskaya. L. M. ( 1969). "Rain" and "antirain" of dead aquatic organisms in the sea. In Biological Problems of the Oceanography of the South Seas, pp. 125-217. Naukova dumka, Kiev, (in Russian) Zhelezinskaya, M.O. ( 1 966). Quantitative mortality indices of the Black Sea plankton in the shallows. J. Zool. 8, 1251-1253 (in Russian). 213 Chapter 6: PRIMARY PRODUCTION Editors: BORIS V. GLEBOV & STEPHEN I. ZEEMAN 6.1 Primary Production of Organic Matter MIKHAIL N. KORSAK Institute of Global Climate and Ecology, State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR Introduction The Bering and Chukchi Seas are situated in the subarctic and arctic regions of the Pacific and Arctic Oceans. They are among the most productive regions of the oceans. Consequently, these areas are of great significance from the standpoint of fisheries. For example, the annual output of the sea products in the region of the Bering Sea is approximately 3 million tons, including I million tons of fish (Sorokin et al., 1983). The results of previous research conducted in the Bering Sea showed that, from the point of view of productivity, this basin is comparable to the upwelling regions of the Pacific and Atlantic Oceans (Sorokin, 1973;Izrael&Tsyban, 1981;Korsak, 1982, \985; Sorokin etal., 1983; Tsyban, 1985; Tsy ban (-/«/.. 1985). The amount of annual gross primary production in the Bering Sea is about 1-1.5% of the total primary production of the Worid Ocean (Sorokin et al.. 1983; Korsak, 1985). The amount of organic production reaches 7 g C m - d ' in some regions of the sea during the period of biological succession of the plankton community. This allows us to classify the Bering Sea as a eutrophic water basin (Sorokin. I973;Korsak, 1982; Sorokin era/., 1983; Tsyban efrt/., 1985). In contrast to the Bering Sea. the ecological system of the Chukchi Sea has been explored to a much lesser degree. The existing data from the literature, however, allow one to presume that the productivity of this basin is also rather high (Sorokin. 1973; Korsak. 1982). According to the classification of waters of the World Ocean, proposed by O. A. Koblents-Mishke etal. ( 1970), the Chukchi Sea is considered to be mesotrophic. The amount of net production of the region is 35-55 g C m- annually (Sorokin, 1973). For the purpose of comparison, it should be noted that this amount for the Bering Sea is 90 g C m -. The amounts of primary organic production in the Bering Sea and in the Chukchi Sea were determined during the course of the Third Joint US-USSR Bering & Chukchi Seas Expedition on the Research Vessel (R/V) Akademik Korolev in July- August of 1988. In contrast to the previous expeditions of 1 98 1 and of 1984, the research conducted this time covered a much larger area of the Bering Sea. including the insufficiently studied northwestern and northern regions of the sea, the Bering Strait, and the southern part of the Chukchi Sea. Materials and Methods The measurements of phytoplankton primary production were performed at 23 stations in the Bering Sea and 1 1 stations in the Chukchi Sea during the period from July 28 through August, 1988. The determination of phytoplankton production was conducted with the bottle method and '^C modification proposed by Sorokin (Sorokin, 1973; Sorokin et al., 1983). The depth of the euphotic zone was assumed to be equal to triple the Secchi disk transparency. The samples were taken with 5-1 Niskin bottles from depths of 0.5, 5, 10, 15, 25, and 45 m. As a rule, incubations were started in the morning and continued for a 6-hour exposure period. Seawater samples were incubated in a flowing seawater bath, located on the deck of the ship in conditions of natural light. Special experiments determining photosynthetic dynamics during the day were performed in order to calculate the daily production values. Radioactivity of the '^C labeled phytoplankton retained on the filters and of '^C isotope solutions was measured with the use of a scintillation counter, "Rack-P ,"' in the course of the voyage. The biomass of phytoplankton was calculated on the basis of chlorophyll concentration, with the assumption that chlorophyll accounted forO.3% of total organic content of phytoplankton. For calculation of daily values of F/B coefficients, it was assumed that the amount of organic carbon in the biomass of seaweeds is 6%. Results and Discussion The third complex ecological expedition started its work at the end of July 1988 in the region called East Polygon. This area is situated in the central part of the Bering Sea, near Pearle canyon. According to the results obtained during the expeditions of 1981 and 1984, the amounts of primary organic production in this area of the sea during the middle-to-end of biological summer were 430-530 mg C m - d ', and the values of P/B coefficients were 0.48-0.56 (Izrael & Tsyban, 1981; Korsak, 1982, 1985; Sorokin e/ a/., 1983; Tsyban, 1985; Tsyban era/., 1 985 ). The results of the measurements of primary production in the East Polygon during the third ecological expedition give ground to suppose that the development of phytoplankton on Stations 1-5 took place rather actively. The average values of primary production at these stations were approximately 1,300 mg C m- d ', with a station-to-station range of 840 to 2,600 mg C m' d ' (Tables 1, 2; Fig. 1 ). The value of P/B coefficient varied from 0.84 to 1.6. It is obvious that significant variations of the primary production indicate high heterogeneity of water masses in this region during the research period. Further experiments on determination of primary organic production were done in the Gulf of Anadyr. This region is comparatively less studied, from the point of view of production biology, than the rest ofthe Bering Sea (Fig. 1). At the entrance to the gulf, on Stations 6 and 7. the level of primary production 215 TABLE 1 Primary production (mg C nr' per day) at given depth for stations of the Bering Sea. Depth Station (m) 1 2 3 4 5 6 7 12 13 29 22 83 86 89 92 96 100 102 0.5 250 1,900 780 140 64 150 15 230 95 47 260 22 520 140 5.1 82 53 40 5 90 2,250 810 85 120 146 20 240 69 34 242 28 270 82 7.7 68 41 18 10 58 1.250 390 11 48 58 11 - - - 11 83 - 3.4 - 29 5.2 15 18 280 11.0 4.3 9.6 9.2 10 36 11 9.3 31 3.6 42 19 2.1 7.4 13 4.4 25 5 3.8 4.7 0.14 1.3 1.5 0.15 2.3 1 0.47 0 0.3 2.1 0.25 0.15 0.5 0.7 0.4 ?• 1,500 2.600 830 810 1,000 980 290 2.800 880 450 2.800 190 2,5001,070 82 750 560 240 B" 1.0 2.6 0.84 1.0 0.44 0.62 0.34 0.26 3.0 - - 0.76 3.5 1.4 0.6 3.5 1.5 0.6 P/B 1.6 1.0 1.0 0.84 2.5 1.6 0.90 - 0.28 - - 0.37 0.91 0.71 0.14 0.21 0.37 0.4 * Integral primary production (mg C m - d ') ** Integral phytoplankton biomass (g C m -) TABLE 2 Primary production (mg C m ' d ') in the Bering and Chukchi Seas. Depth Station 1 (m) 32 104 106 109 112 45 49 50 53 55 57 59 64 68 69 74 0.5 350 77 86 2.5 5.0 36 20 21 31 37 21 30 3.6 2.9 112 97 5 270 57 67 4.8 10.5 27 19 26 50 76 23 33 82 14 150 104 10 120 - 26 1.7 16 16 28 53 140 - 290 13 9 130 15 46 8.5 10 0.5 1.2 5 15 9.4 46 290 - 206 - 9 75 25 3.5 0.5 0.3 0.00 0.04 14 5 2.6 34 1-^0 75 195 42 0.4 24 18 45 - - - - 0.11 0.4 0 0.9 - - - - - - - P" 3,210 680 720 38 100 420 404 390 1,400 4,700 1.070 2,400 - - 970 2,020 B" - 1.3 0.78 0.56 0.40 5.0 - 0.13 0.84 16 5.0 2.8 - - 3.0 1.9 P/B - 0.52 0.92 0.07 0.25 0.08 - 3.0 1.7 0.29 0.2 0.86 - - 0.32 1.0 * Integral primary production (mg C m - d') ** Integral phytoplankton biomass (g C m -) 216 Chukchi Sea Fig. 1. Distribution of primary production in the Bering and Chukchi Seas (July-August, 1988). Values are represented in mg C/m- day. was 980 and 290 mg C m- d ', respectively (Table 1). The level of primary production at stations located in the gulf itself varied from 470 mg C m- d' at Station 19 to 3,200 mg C m - d ' at Station 32 (Table 1). The average value of primary production in the Gulf of Anadyr was 1,850 mg C m - d ', and the average value of the P/B coefficient was 0.8. It should be noted that the highest values of phytoplankton production were obtained in the western part of the gulf (Tables 1.2). In the eastern part of the gulf, the production of phytoplankton was considerably less (Fig. 1 ). The research on determination of primary production of phytoplankton in the Chirikov Basin showed that in the middle of August, the value of primary production was approximately 1,800 mg C m' d ' in the western part of the gulf, 600 mg C m- d ' in the central part, and only 320 mg C m - d ' in the eastern part of the gulf (Table 1 ). It should be noted that the peculiarities of the distribution of primary organic production in the northwestern and northern regions of the Bering Sea observed during the expedition are very closely correlated with the quantity of nutrients and the quantity of phytoplankton in these regions of the sea. Thus, according to the results obtained by the American research workers who participated in the expedition on board the RTW Akademik Korolev, the stations richest in nutrients and chlorophyll a were situated in the western part of the research area. An especially high concentration of chlorophyll a (55 mg Chi m') was discovered in the Gulf of Anadyr. High productivity of the Gulf of Anadyr waters can be explained by the topographically induced rise of deep waters. These waters are rich in nutrients and are brought into the photosynthetic zone by the transverse current along the shelf The same current, which provides high productivity of the Gulf of Anadyr, moves further on to the north, along the eastern Soviet coast and Saint Lawrence Island into the Chirikov basin. Situated between Saint Lawrence Island and the Bering Strait, the Chirikov Basin differs significantly from the Gulf of Anadyr. Cold waters, rich with nutrients, are located along the Chukchi coast. Alongthecoastof Alaska, however, there are low- salinity, low-nutrient shelf waters, which result from runoff from the coast. According to the data obtained by the American specialists, the concentration of chlorophyll a in this area was only 1-5 mg m - at that time. The investigations in the southern part of the Bering Sea were performed at the end of August, in the region called South Polygon. The amounts of phytoplankton production at stations in this region were comparatively small, 40-105 mg C m - d ', which seems to be typical for the period of biological autumn. During the expeditions on the RA"s Shirshov and Akademik Korolev, in 1981 and 1984, this region was investigated one month earl ier in the period of the middle of biological summer. Naturally, the values of primary production measured at that time were a bit higher for this region: on average, 190-320 mgCm-d'(Tsybanf/ a/., 1985). At the same time, the values of P/B coefficient were 0.11-0.71. This indicates relatively high intensity of photosynthesis, which is an important characteristic for the period of biological summer. The values of P/B coefficient during the third ecological expeditions on the stations of this region were 0.40-0.56. Concerning vertical distribution of primary production in the Bering Sea, it should be noted that, similar to the research of 1981 and 1984, the depth of the euphotic zone during this time did not exceed 45 m (Tables 1,2). As a rule, the vertical profiles of primary production had a maximum located within the area of optimal light conditions at 5- 1 0 m or more seldomly in the surface layer. The values of primary production below this maximum decreased monotonically (Tables 1 ,2). Consider that the average of the primary production of phytoplankton at the stations in the Bering sea was about 2,200 mg C m- d ', according to our data. Furthermore, according to the data obtained by V. M. Kudryatsev (Subchapter 4. 1 .2, this volume), the average of bacterial degradation in the photic zone of the Bering Sea during the period of our research work was 6, 1 00 mg C m - d ' . The value of the P/D - coefficient, which was used as an indicator of the balance between the processes of synthesis and destruction of organic substances in the Bering Sea ecosystem, was 0.36 during the period of the end of biological summer to the beginning of biological autumn. Besides the studies of the Bering Sea ecosystem during the course of the expedition on board the R/V Akademik Korolev, we pert'ormed ecological pelagic research of the eastern sector of the Arctic basin, that is, the Chukchi Sea. The average value of primary production in the southern part of this sea was 1,700 mg C m - d '. This fact indicates that the productivity of this area of the Chukchi Sea is very high (Table 2). The highest rates of photosynthesis were discovered in the central part of the basin, at Station 55 (Table 2). The minimum values of phytoplankton production were obtained in the course of 217 measurements in the eastern part of the basin, at Station 67 (Table 2; Fig. 1). Comparatively small values of phytoplankton production, about 400 mg C m - d ', were found at Stations 45, 49, and 50 (Table 2; Fig. 1). As was shown by the oceanographic and hydrochemical research conducted by the American scientists during the expedition, high productivity of the central and western regions of the Chukchi Sea is explained by the penetration of waters rich in nutrients, from the Anadyr current into these areas. In addition, the western regions of the sea could be also influenced by the flow of more saline and nutrient-rich waters moving to the south along the coast of Siberia. Together with Anadyr water brought from the Bering Sea, the above-mentioned current can provide the rather high productivity of the Chukchi Sea. The maximum concentration of chlorophyll, according to the data obtained by the American specialists during our expedition, reached 77 mg Chi m '. Shelf waters of the Chukchi Sea along the coast of Alaska are considerably less enriched with nutrients. Correspondingly, the concentration of chlorophyll and the values of primary production are much smaller in the eastern regio.is of the Chukchi Sea (Table 2; Fig. 1 ). Because of the somewhat greater transparency of waters in the Chukchi Sea, the depth of the euphotic zone there was correspondingly deeper. However, similar to the Bering Sea, it did not exceed 45-50 m (Tables 1.2). The maximum values of phytoplankton production were usually found at depths between 5 and 15 m, which is probably related to optimal light conditions. More seldom, the maximum of primary production in the Chukchi Sea was discovered in the surface layers of water (for example, on Stations 45 and 49) (Table 2; Fig. 1 ). Thus, the research of primary production in the Bering Sea, conducted during the expedition on board the RA' Akademik Korolev in 1988. made it possible to determine the level of productivity of the central, southern, northwestern, and western regions of the Bering Sea, including the Bering Strait for the period of the end of biological summer to the beginning of biological autumn. The results obtained indicate high productivity of the Bering Sea ecosystem and great heterogeneity of water masses from the point of view of biological parameters. The data on the rates of photosynthesis in the Bering Sea ecosystem, obtained in 1988, complement and extend the results obtained in the course of expeditions in 1981 and in 1984. The results from the previous expeditions characterize the status of plankton community of the Bering Sea during the period of summer phase of the seasonal succession of plankton community, while the results of the latest expedition cover the period of biological autumn. The results, which were obtained during the joint US-USSR ecological expedition in the Chukchi Sea, give an idea of the level of productivity of the region during the period of biological autumn. 6.2 The Importance of Primary Production and STEPHAN I. ZEEMAN Department of Life Sciences, University of New England. Biddeford. Maine. USA Introduction The high-latitude seas are among the most productive regions of the world (Koblentz-Mishke et al., 1970). This is despite the low temperatures encountered here and the severely reduced sunlight during the winter. The cold may even aid in the transfer of energy to higher trophic levels since this reduces metabolic requirements and losses through respiration ( Pomeroy & Deibel. 1986). The Bering Sea has been the focus of recent investigation by a team of scientists from the USSR and the USA (Whitledge et al.. 1988). The data reported here is a continuation of the effort begun in 1984 to characterize the oceanography of the Bering Sea with respect to the importance of phytoplankton primary production. High production rates and biomass values have been reported throughout the Bering Sea(Koikee/a/., 1982;Sambrottoe?a/., 1984, 1986; Whitledge etai. 1988). In the present study, the investigations extended into the Chukchi Sea and areas of limited access. An important function of phytoplankton production is the transfer of energy through food webs, which may ultimately result in higher levels of production of commercially important species. The Bering Sea is important in the production of finfish and shellfish (Hood & Kelly. 1974). It is the largest source of Pacific pollock, amounting to about 1.1 million metric tons (Washburn & Weller, 1986). This rich resource must be managed to sustain the populations, and this entails assessing the available food resources. Global climate change has come to the forefront of public attention with the international public, private, and scientific sectors becoming concerned about the possible consequences. Among the major unknowns in the global climate research is the function of ocean systems. Potentially, the oceans could 218 serve as a very large reservoir for storage of anthropogenic CO,. The physical, chemical, and biological mechanisms still are not well understood. It has been suggested that the capacity of the oceans to store CO, may have been overestimated {Brewer etal.. 1989). However, much research still needs to be conducted before an accurate understanding of the role of the oceans emerges. TTie Bering Seaecosystem may be an important area for storing carbon, both by burial in the sediments and via transport to areas of deep-water formation. Materials and Methods Primary productivity measurements were carried out at 30 of the 1 13 stations occupied (Fig. 1). Standard '^C methods using liquid scintillation counting were employed on samples from two depths. One sample was collected near the surface, the other from the subthermocline layer. The latter from the light absorption maxima if one was identified by a SeaTek //; situ beam transmissometer. Samples were collected with 8-1 Niskin samplers and samples from each layer were homogenized in a 20-1 carboy prior to subsampling. Triplicate subsamples were incubated with 2.5 ^ Ci NaH'^'CO, at each of eight light intensities from 0.25 to 200 |a Ein m - s '. Fluorescent lamps were used as the light source. Additional samples were kept in total darkness and at ambient, sea-surface, natural light. Incubations took place in water-cooled chambers at near- ambient sea-surface temperature. After 1-h incubations, samples were filtered through 0.4 |i m pore Gelman metricel filters. Filters were acidified in vials with 0.5 ml 1 .0 N HCl and counted in Ecolume scintillation cocktail (ICN Biomedicals, Inc.). Primary production rates were calculated and normalized to chlorophyll a concentrations (Strickland & Parsons, 1972). Alkalinity and total CO, concentrations were estimated by titration (Strickland & Parsons, 1972). Chlorophyll was determined fluorometrically by G. Holmes and W. Robie at the time ofsampling (Strickland & Parsons, 1972). Photosynthesis versus light intensity (P-I) parameters were estimated with a hyperbolic tangent function (Jassby & Piatt, 1976) and with a function incorporating photoinhibition (Platte/ a/., 1980). I'he best fit model was determined from the sum of squares obtained by using nonlinear least-squares regression (Systat, Inc.). Incident sea-surface light intensity was monitored continuously with a photosynthetically active radiation (PAR) sensor (Li-Cor LI-I92S) mounted on a post removed from most light interferences and connected to a data logger (Li-Cor LI- 1 000). Subsurface light was measured and the extinction coefficients calculated at each station with a LI- 1 85 quantum meter equipped with a LI-192S sensor (Li-Cor). The incident light, extinction coefficients, chlorophyll versus depth distribution, and P-I parameters were used in a numerical model to calculate integral production through the water column throughout the day. The program was written in Fortran 77 (Lahey Computer Systems) and could also be used to calculate seasonal and annual estimates of production. Results Figure 2 shows incident surface light intensity (as photon flux density). The maximum values ranged from about 350 to 1,900 |i Einm-s'. Storms were common near the Aleutians and the Polar Front, which accounted for some of the PAR variability. The areal primary production throughout the Bering and Chukchi Seas was relatively high, with a mean of 1.8 g C m-d'. The maximum value estimated was 15.3 g C m-d ', while the low value was 0.174 g C m- d '. The distribution of primary production had several peaks throughout the region, especially in shallow waters on the shelf. Not all the shelfarea was productive, however. Some of the lowest values recorded during this cruise occurred south of 2000 n 1500- Cfi M I 1000 500- ovm Day Fig. 1. Locations of stations where primary productivity was measured. pjg 2. Photon Hux density (15 min means) measurements taken during the cruise. July-August, 1988. 219 St. Lawrence Island. The massive changes in the production rates from south to north are most obvious in the three- dimensional representation shown in Fig. 3. The highest value (15 g C m-d') was found at Station 36 near St. Lawrence Island. There were also secondary peaks at Station 55 in the center of the Chukchi Sea (5.4 g C m -d '), Station 69 in the Chirikov basin (4.4 g C m-d '), and Station 24 in the Gulf of Anadyr (3.6 g C m-d'). A further breakdown of the data (Table 1) shows the values at each station with means for various regions. Daily Areal Primary Production 36 Fig. 3. Three-dimensional plot of primary productivity estimated during this study. Horizontal contour intervals are 1000 mg C m- d '. The numbers of selected stations are shown for orientation. Inset shows , limits of the contoured region. Much of the primary production was subsurface, with significant amounts below the themiocline in nutrient-rich waters. The importance of subsurface production is shown in Fig. 4. The peak in Fig. 4 is about 300 mg C m 'hr ' at a depth of31 m. The high carbon assimilation rates are not necessarily coincident with high chlorophyll ci values as shown in Fig. 5. The major subsurface production peak at 63.5°N is in a region where chlorophyll values were only about 1 mg m '. In another area at 67°N there was a peak in chlorophyll that was not associated with a production maximum. The productivity peak, however, is associated with a nutricline as evidenced by the NO, + NO, contours shown in the lower panel of Fig. 5. The P-I parameters were relatively uniform over the study area as shown by the P„„, values in Figs. 6a and 6b. The values were generally less than 1 0 mg C ( mg Chi ) ' hr ' , although some exceptional values were higher. Surface P„„, values were also generally higher than those from the deeper samples. Predictive modeling of primary production throughout the season based on calculated solar irradiance (Brock, 1981), but without taking account of ice cover, is shown in Fig. 7. Table 1 Areal productivity in various regions on a daily and hourly basis. The means for each region are presented ± 1 standard deviation. Region Station mg C m- d ' mg C m - hr ' Bering Shelf 4 918.33 91.81 6 105.63 11.02 9 744.33 60.38 18 1,222.98 111.71 19 751.85 82.53 35 483.13 56.93 Mean 704.37 ±381 69.1 ±34.95 (Station 36) 36 15.252.19 1596.61 Bering Deep 109 1,885.09 256.12 112 1,769.59 140.0 113 2,041.39 273.99 Mean 1.898.7 ± 1.^6 223.4 ±72.8 Gulf of Anadyr 24 3,599.01 405.45 27 548.11 71.99 32 1,698.07 173.52 Mean 1,948.4 ± 1540 216.9 ± 170.9 Anadyr Strait 41 1,722.97 175.39 Bering Strait 83 206,92 24.9 86 1,417.18 164.8 Mean 812.04 94.85 Chukchi Sea 45 503.55 72.66 49 1,222.03 127.40 50 375.61 51.03 55 5,450.28 396.71 57 264.88 32.71 59 1,949.28 302.77 64 150.64 18.41 69 4,444.64 521.93 74 241.8 32.32 Mean 1,622 ± 1987 172.9± 186.8 Chirikov Basin 89 3,163.37 346.09 96 760.05 81.91 100 604.25 89.6 102 143.0 23.76 106 494.46 39.73 Mean 1,033 ±1212 116.2± 131.5 The notable points here are that the baseline of the graph slopes downward from south to north, but the peaks of production increased from south to north. This may be related to interactions of limiting light and nutrients, or possibly the temperature gradient. In relation to the international interest in global climate change, the importance of the Bering Sea was also evaluated by estimating the ZCO, at all primary productivity stations (Table 2). Estimates of ZCO, flux through the Bering Straits was calculated from the total transport of about 1x10'' m's' 220 mg C m ^ hr~* n«i Fig. 4. Three-dimensional plot of primary productivity rates estimated along a transect from the Aleutian Islands to the Chukchi Sea. The major peakatStation.^6reaches300mgCm 'h 'at a depth of."* I m. Selected station numbers are indicated for orientation. (Favointe, 1974). Instantaneous shipboard measurements were close to this value, although a realistic estimate of the mean flu.x might be closer to 0.5-0.8 Sv (Coachman, personal communication). Transport of CO, was calculated from the average of surface and thermocline estimates of Z CO, and the 1 Sv transport. This comes to 35.3 x 10'' moles C yr ' on the eastern side of the strait and 32.8 x 10'- moles C yr ' on the western side. The combined east and west side transport would then be 0.82 x 10'' metric tons C per year. This provides an estimate of the flux of dissolved CO, but does not account for particulate flux. The present study cannot derive a value for the total particulate tlux but can estimate phytoplankton biomass and, therefore, phytoplankton particulate carbon flux. During the Latitude Fig. 5. Contour plots of primary productivity, chlorophyll a, and nitrate plus nitrite concentrations along a transect from the Aleutian Islands to the Chukchi Sea. cruise we occupied transects on either side of the Diomede Islands. The measured chlorophyll concentrations averaged 5.72 g Chi m ' on the western side and 1.1 g Chi m' on the eastern side. Taking the mean chlorophyll concentration for both sides and multiplying by the approximately 1 Sv transport results in an estimated annual particulate phytoplankton flux. Assuming a C/Chl ratio of 30, and that the chlorophyll concentrations remain unchanged seasonally, then the annual flux would amount to 3.2 X 1 O** metric tons C per year. This is about 0.4% of the estimated dissolved carbon flux. Other particulate material, either detritus or living, could contribute significantly to the total particulate carbon flux. Therefore, the relative magnitude of particulate versus dissolved transport will need to be investigated further. Another aspect to consider is how much carbon is fixed by primary production regionally. For example, in the region north of the Bering Strait, the cruise track covered approximately 85,320 km-. The average rate of primary production in the Chukchi was 1.6 g C m-d' (Table 2). Assuming a 60-day growing season, the southern Chukchi would fix roughly 8.2 X 10*" metric tons of carbon. A similar calculation for the Chirikov basin obtains a seasonal production of about 221 3.12 ^ 10" metric tons. The area of the Bering Sea is 2.268X 10''km-(Sverdrup<'?a/., 1942). The mean productivity rate for the entire Bering Sea (excluding Station 36) amounts to 1 .4 g C m - d ' , or 0. 1 9 X 10'' metric tons during the growing season. Discussion Oceanographers have become more aware of the importance of primary production in the Bering Sea since the charts of Koblentz-Mishke fro/. ( 1970) were published. More recent estimates of the magnitude of primary production range 40-1 30- X 20 10 0- Surface y H \- h t- h i-_ '-)- - 1 0- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 0 20 40 60 80 100 120 Station Fig. 6a. P„j, values for surface samples obtained during the summer of 1988. 40- 30- X 20 cu 10 h H - \- Deep h ^ h - -~^h — 1 0 I I 1 1 I r I I I I I I M I I I I I I I I I I I I I M 1 [ I I I I I I I I I I I I I I I I 1 1 I I M I I I I I I I I 0 20 40 60 80 100 120 Station Fig. 6b. P„,„ values for samples from below the Ihermocline. and in the deep chlorophyll maximum layer when one existed. Fig. 7. Results from numerical model simulating production through an entire year, based on summer P-I values, and neglecting ice-cover. Table 2 ECO; during Summer 1988 in the Bering and Chukchi Seas, for samples from the surface and a deeper layer below the thermocline. SCO, (mM) Region Station Surface Sub-Thermocline Bering Sea 6 and 9 Gulf of Anadyr 18 19 24 27 32 35 36 Chukchi Sea 41 45 49 50 55 57 59 64 74 Bering Strait 83 86 Chirikov basin 89 96 100 102 106 2.124 2.014 2.027 2.014 2.049 2.061 2.052 2.052 2.027 2.037 1.609 2.043 2.090 1.910 1.950 1.620 2.070 2.068 2.231 1.997 2.052 2.210 2.010 2.102 2.010 2.183 2.024 2.024 2.264 2.202 2.021 2.021 2.027 2.205 2.208 2.115 2.068 1.990 2.170 2.060 2.130 2.099 2.250 2.160 2.090 2.220 2.220 2.190 2.130 m to the grams of C m -d ' (Whitledge et ol.. 1988). Fisheries scientists were aware long before that this was a region of rich productivity (Hood & Kelly, 1974; Washburn &Weller, 1986). The present study adds new data to this knt)wledge base. It also confirms the patterns seen in the 1984 cruise. First, the regions of upwelling and associated high production were again seen, thus verifying that this is a continuing phenomenon. Second is the large expanse of the deep production maximum. The tighter grid spacing of stations in the present data set allowed a clearer picture about the extent of these phenomena and showed that they were localized in the region of the northern Bering Shelf and the Chukchi Sea. Figure 5 shows the productivity, chlorophyll, and NO3 + NO, concentrations along a north-south transect. The patterns show that the highest production occurred where there was upwelling of nutrient rich water. This tongue of water broke through to the surface between 64° and 65°N. Furthermore, P^^^ was generally lower in deep water than in the surt'ace waters at the same location. At Station 36 (63°25'N, 172°10'W), however, the P„^, values were nearly identical in surface and deep waters. These values were also higher than at most of the other stations (Fig. 6). The subsurface position of the primary productivity peak indicated that the phytoplanktoh were possibly nutrient-limited in the surface waters. At stations where upwelling appeared most intense and nutrient concentrations were greater, the productivity rates were high. However high, these rates were still not as great as in areas where the water column was stratified. The magnitude of vertical currents in the upwelling regions transport the phytoplankton from high light to low light and back. This circulation takes place at time scales that do not allow physiological adaptation. Cellular levels of chlorophyll and photosynthetic enzymes cannot be adjusted as rapidly as changes in light intensity. In the Chukchi Sea, the productivity maximum (between 67° and 68°N ) was generally in the surface waters. Chlorophyll concentrations there were also high, with a maximum centered around 15 meters in depth. The contribution to total water column production was greater at the surface than at the chlorophyll maximum. This was due to the shading of the deeper populations. This was not so at Station 36. however, where surface chlorophyll concentrations were below 2 mg Chi m '. Overall, the primary productivity of the Bering and Chukchi Seas was controlled by hydrographic conditions. There were high photosynthetic rates near the Aleutian Islands ( 1 .9 g C m -d"'), but not neariy the magnitude of those found at higher latitudes (15 at Station 36). On the continental shelf, there appeared to be a decline in production (0.7 g m'd ') and a lower nutrient regime in the surface waters. This is indicative that the populations there were nutrient-limited. The nutrient stress was alleviated further north on the continental shelf. Nutrient enrichment on the continental shelf was due to upwelling and served to stimulate production. In the region of the Bering Strait, topographic conditions led to turbulence and enhanced mixing of the water column (including the phytoplankton). The instability reduced production to some extent ( 1.4 g m -d '). In the Chirikov basin and the Chukchi Sea, the stability of the water column was greater while nutrient concentrations remained high. This combined effect produced high photosynthetic rates (1-1.6 g m"-d'), especially in the central portion of the area (5.4 g m-d '). It was clear from the data that the source of nutrients was the deep Bering Sea water. This water mass upwelled onto the continental shelf (see Coachman & Shigaev, Subchapter 2.1, this volume). The northward flow then provided a source of new nutrients and a standing stock of phytoplankton to the Chukchi Sea and Arctic Ocean. There also appeared to be a northern source of nutrients for the production maximum in the Chukchi Sea (.see Coachman & Shigaev. Subchapter 2.1. this volume). The origin of these nutrients is uncertain, but they may be from the region near Wrangel Island and flow off the Siberian coast. Some of these nutrients may have come from the Bering Sea and be recirculating around the basin from the previous year. The distribution of production, interestingly, nearly matches the northern distributions of historical whaling data (Nasu, 1974). The regions of high primary production also match historical dataofhighbenthicbiomass(Alton, 1974). Recently, the link between phytoplankton production and high benthic metabolism was shown by Grebmeier et al. (1988, 1989) for the Bering and Chukchi Seas. Although food webs in oceanic systems are difficult to quantify, the case of the Bering and Chukchi Seas seems fairly clear. A major pathway is for phytoplankton to sink to the bottom where they serve as a carbon source for a detrital food web. This food web ultimately feeds pollock and large mammals such as walrus {Odobeims rosmarus) and the gray whale (Eschiichtius gihhosus). Grebmeier ef «/.( 1 989 ) have implicated interannual variability of phytoplankton production as the causative agent for interannual variation in oxygen consumption rates in Bering Sea water. Another major pathway is more typical of pelagic systems, and that is through zooplankton. The relative importance of these two pathways was not studied, but it seems that in the northern Bering and Chukchi Seas, a large proportion must go through the benthic pathway. The importance of the Bering Sea phytoplankton does not end with food webs alone. The biology and chemistry of the Bering Sea might serve as major modulators of atmospheric CO,. The present study shows that about 166 metric tons of C are taken up by phytoplankton a year. Much of this is, of course, remineralized (Grebmeier et al.. 1989), but a fair fraction is buried in the sediments. A second mechanism of isolating carbon from the atmosphere is also possible. There are two major sources for the formation of bottom water in the oceans, the Antarctic, and the Norwegian Sea. Prior studies have shown that there is a transport of about 15 Sv into the Bering Sea from the North Pacific (Favorite, 1974). Most of that flow returns to the North Pacific. Still, about 1 Sv passes through the Bering Strait into the Arctic Ocean (Favorite, 1974) where circulation could bring it to the North Atlantic. Since much of the flow would be in deeper layers and under the ice cap. little of the CO, would be transferred back to the atmosphere. With the appropriate temperature and salinity, this water could form North Atlantic bottom water. An interesting thought here is that during the 223 winter, polynyas form in the Bering Sea near St. Lawrence Island allowing surface water to supercool. Extremely cold and highly saline waters have been found southwest of St. Lawrence Island (Takenouti & Ohtani, 1974). Such cooling reaches the bottom in the northern Bering Sea where the shelf region is generally shallow (Ohtani, 1969). The cold water would have a higher loading of CO,. Walsh et al. ( 1 985 ) have shown that much of the production on the shelf may be transported off the shelf. The off-shelf transport to deeper water in the Bering Sea could act as a sink for carbon. Similar transports occur off the shelves in the Arctic Ocean. The winter is also when strengthened flows are expected to occur due to meteorological forcing. Thus there would be an increased transport of water and CO, through the Bering Strait. Thewinter flows could supply source water for deep water mass formation. These water masses could form either in the North Adantic or in the North Pacific via outflow along the Kamchatka Peninsula. A salient point here is that in the Atlantic, the southward transport of CO, is only 0.26 gigaton of C per year (Brewer etal., 1989). This is a relatively small quantity in comparison to the annual production of CO, (about 5.5 gigaton). Thus, magnitude of the net Atlantic transport, while relatively small, is of the same order as the estimated Bering Strait northward transport (0.82 gigaton). Certainly not all the carbon in the Bering Sea flux finds its way to the Norwegian Sea, but it could be a significant contribution. Thus, the quantity of carbon stored in the North Atlantic bottom water may be in good part due to the flow from the Bering Sea. Additional storage of carbon may result from transport of particulate carbon to the deep basins of the Bering Sea. The Maine Undergraduate Science Consortium. MEDUSA, Contribution No. 010. 6.3 Intensity of Biosedimentation Processes BORIS V. GLEBOV' , VLADIMIR I. MEDINETS* , and VLADIMIR G. SOLOVIEV* * Institute of Global Climate and Ecology, State Committee for Hydrometeorology and Academy of Sciences. Moscow. USSR * State Oceanography Institute. Odessa. USSR Introduction Materials and Methods Marine organisms play an important part in the sedimentation processes. The influence of biotic processes upon sedimentation provides evidence of active participation of marine organisms in the biological accumulation (concentration) of chemical substances. They are also important in the subsequent transfer of these substances through organic products (organism remains, feces, etc.) or by the organisms themselves to the deep layers of the ocean and the bottom. The biotic processes directly or indirectly determine transformation and distribution of essentially all the elements in the sea. Changes occur in the physical and chemical form of the elements during these transformations. The organisms may accumulate essential elements as well as useless and even detrimental ones. The chemical substances are circulated from the external environment into the organisms and back by typical routes. These processes thereby form relatively closed biogeochemical cycles whose rates vary for different substances. The influence of marine organisms on geochemical mobility may be broken into biological accumulation and sedimentation stages (Lisitsyn, 1983). The essential regularity of these processes can be used to develop methods of determining the biosedimentation rates on the basis of vertical distribution of the elements differing from each other in their biogeochemical activity. With this in mind, it is logical to use natural radionuclides as tracers. Their concentration can be measured in the medium with a highly sensitive radiometric apparatus (McKee et al., 1984). From the middle of the sixties there began an intensive study of the distribution in the ocean of the two genetically connected natural radionuclides, -'^Uranium and -'""Thorium. -'^Thorium is the product of -'*U a-decay. This process of radioactive decay is the main source of -"Th in the sea. As shown previously, these isotopes display a shift in the radiochemical balance in ocean surface-water (Bhat et al.. 1969; Matsumoto, 1975). This shift is due to biological accumulation and biosorption of Th by planktonic organisms and suspended organic particles, which are then removed from the surface layer as a result of sedimentation. The bioaccumulation factors of Th for different types of plankton organisms in open ocean range from lO"* to 2 x 10' (Barinov et al., 1967). The average values of accumulation factors forTh in suspended organic particles are the same order of magnitude (Cherry & Shannon, 1974). -"^Uranium is relatively evenly distributed in the oceanic waters, where its concentration is about 3 |ig/l. Furthermore, the accumulation factors in plankton and detritus are some 3 to 5 orders of magnitude lower than those of thorium. Thus, the shift in the radioactive balance is in fact determined by the changes in the concentrations of -"Th due to its transfer in the process of biosedimentation. Knowing the vertical profile of these radionuclides, it is possible to calculate the sedimentation rate of the suspended organic matter (Polikarpov f/ 1//., 1976. 1980). 224 -"Thorium balance in a single volume of seawater is described by equation: The flux from the surt"ace water layer at depth H is determined as follows: ^A';- where (7) Njj^ — -"Th atoms concentration in sea medium; A'^ — -'*U atoms concentration in sea medium; X^ — -w-j-j^ radioactive decay constant; A.j^, — -'''U radioactive decay constant; k — factor of -"Th accumulation in suspended organic substance; P — rate of biosedimentation removal of suspended organic substance from single water volume. The general solution of differential equation ( 1) in relation to A'^ is as follows: ^n.,n = ^v.,0, • \' h -{X„+lfPi-i •P)J^ ^n,ore (X„,+k''Pj-\ \ -{\,,+ k- P}y -(X„ ^ If PI- 1 (2) where N^.„„ and Nyh,,,,, are -'■U and ''■'Th concentrations respectively, at times zero. Transforming equation (2) with regard for small value \ and N^, = constant to the results in: (3) For steady state conditions (dNj^dt = 0). the biosedimentation rate is determined by equation ( 1 ): P = k • /V,„ (4) Introducing specific activities of -'"U and -"Th in seawater, C^: = N,,'\, and C„, = A'„«Ar„ (4a) and specific activity of Th in the particulate organic matter: Cn'' = Nr„'\,.'k (4b) we obtain the equation to calculate the biosedimentation rate: p _(Q, - C„,) "A,,, ,c, •^ ^ »- ' The residence time of -'"'Th, r„, in the upper layers of water is inversely proportional to the rate of the biosedimental removal of this isotope (Coale & Bruland, 1987): Cr, (C, -C„,) • \„ (6) During the Third US-USSR Joint Research Expedition in J uly-August 1 988 experiments were carried out at 8 stations in the Bering Sea and at 3 stations in the Chukchi Sea. These measurements included the vertical profiles of -"*U and -"Th and the concentration -"Th in particulate organic matter (POM). These data were then used to calculate biosedimentation parameters in the region. The "^U concentrations in seawater were calculated based on the close correlation of -'-U with salinity (Turekian & Chan, 1971;Ku£'f(;/., 1977): Ci, = 0.07081 'S (8) where Q = specific activity of -"U (dpm l-^y,S = salinity ("/qo). -"Thorium concentrations were determined separately in filtered seawater and in POM. The POM samples were collected at 3-4 depths within the upper 100-m layer. The water (about 1 m') was forced by a vibrating immersion pump through a "Midiya" filtration unit. The filters were FPP-15-1.5, which retained suspended particles larger than \i 0.5 m (Vakulovsky. 1986). The following procedure was used to determine -"Th concentration in the filtered water. In plastic tanks cosedimentation of Th(4+) with Fe(3+)-hydroxide was performed on 100 1 of water. The precipitate was isolated by paper filtration, dried, and redissolved in 50-100 ml 8N HCl. This solution was then brought to a volume of 150 ml with 8N HCl. Thorium was isolated by passing the solution through glass columns packed with cation-exchange resin, Dowex in (H*) form. The resin was ashed at 450-500°C. The ash residue was placed in a scintillation vial, dissolved in about 1 ml of 0.5N HCl, and then 5-10 ml of scintillation cocktail was added. The p-activity of the sample was measured by liquid scintillation counting in a "Rack P-121, Wallac LKB." The radiochemical purity of the -"Th was checked by double measurement of activity , once immediately after isolation and then again 24 days later. The filters with the POM were dried at 60°C. The dry weight of the particulate matter and its concentration in water were determined by the difference in weight before and after filtration. The filters were then ashed in a muffle furnace at 450-500°C and the weight of the ash residue (with correction for ashing of the filter itself) was determined. The ash residue was dissolved in a HCl and HNO, mixture (3:1 ratio) then evaporated in a sand bath. The resulting dry residue was re- dissolved in 8M HCl. Any insoluble residue (silicates) was isolated by means of centrifugation. The supernatant was collected. Then 7 ml of 8M HCl was added to the remaining precipitate, mixed, and centrifuged again. The supernatant was again collected and added to the first collection. The procedure was repeated three times. The combined supernatant liquid was brought to a volume of 1 50 ml with 8M HCl. The -"Th was then determined as described above for the seawater samples. 225 Results and Discussion The calculation of -"*U concentration in seawater was based on salinity data obtained by American and Soviet specialists during the expedition. The calculated results of -"*U concentrations and measured -'^Th content in water and particulates are shown in Tables 1 and 2. Data analysis points to high spatial homogeneity of -'*U within the Bering Sea. The average concentrations of -"*U in the Bering Sea was 2.31 ± 0.01 dpm 1 '. Near the surface the content varied from 2.19 in the Gulf of Anadyr to 2.35 dpm 1 ' in the open waters of the Bering Sea. The vertical profile of -'*U showed a slight increase in concentration with depth. The maximum concentration gradient (in the Gulf of Anadyr) did not exceed 0.0002 dpm 1 '. In the Chukchi Sea, the -"*U concentration varied over a broader range, from 1.73 to 2.39 dpm 1'. and averaged 2.26±0.1 1 dpml'. Only in the western part of the Chukchi Sea, however, were vertical gradients of -'*U concentrations evident and also considerable differences from the average concentration for the sea. This was due to a thin (5-10 m) low-salinity water layer near the surface. Still, as a whole, in the central part of the Chukchi Sea -'"U concentrations were close to the average values for the Bering Sea. The -'^Th vertical profile in the upper layers of the sea is closely correlated with not only the hydrological parameters but also with the rates of the biosedimentation processes. This relationship determines the balance (R) between -'-U and -' ^Th in the euphotic layer: '^ = -p-- (9) In contrast to -'"U, it should be noted that a considerable part of -'^Th, in layers with high suspended loads, is in the POM. Because of this, the ratio of particulate to dissolved forms of -"Th varied considerably from region to region. In the Bering Sea, the total content of -"Th in water and in POM in the upper 100 m layer was in the range of 0.54-1.58 dpm 1'. The dissolved and particulate -"Th concentrations averaged 0.44 ± 0.03 and 0.40 ± 0.05 dpm 1 '. respectively. The R value averaged 0.43 in the Bering Sea. TABLE 1 Concentrations of -"*U and -"Th in seawater and POM of the Bering Sea. Date Station Latitude Depth Q, c„ (dpm/1 1 Longitude (m) (dpm/1) Dissolved Particulate Total svoe^N 0 2.84 0.38 0.29 0.67 1 75^05' W 20 2.32 0.33 0.37 0.83 40 2.33 0.28 0.66 0.94 80 2.34 0.31 0.31 0.62 60°28-N 0 2.33 0.61 0.56 1.17 177°50'W 40 2.32 1.22 80 2.35 1.20 120 2.35 0.76 63°00'N 0 2.23 1.04 176°00-W 20 2.23 1.35 40 2.30 1.50 80 2.36 0.99 63°00'N 0 2.19 1.12 173°00-W 20 2.23 1.23 40 2.27 1.07 60 2.30 1.43 65°14'N 0 2.25 88.66 0.22 0.88 169°2rW 20 2.29 0.39 0.25 0.64 40 2.30 0.54 0.25 0.79 64°23'N 0 2.25 0.27 0.27 0.54 169°09-W 15 2.27 0.59 0.16 0.85 30 2.32 0.99 0.33 1.32 53°59'N 0 2.36 0.38 0.61 0.99 176°00'W 20 2.35 0.29 0.30 0.59 50 2.36 0.62 0.44 1.06 170 2.38 0.59 0.32 0.91 53°irN 0 2.33 0.39 0.39 0.78 177°I8'W 20 2.34 0.26 0.39 0.67 70 2.36 0.58 1.00 1.58 29 Jul : 02 Aug 1 04 Aug 88 06 Aug 88 20 Aug 88 22 Aus 88 n Aug 88 29 Aug 1 35 89 100 110 113 In the Chukchi Sea, the -"Th concentration (dissolved + suspended) was lower (0.81 ± 0.08 dpm 1 ') than that in the Bering Sea. The dissolved -'''Th concentration (0.45 ± 0.06 dpm 1') was the same as in the Bering Sea while the particulate -"Th content was lower, amounting to 0.35 ± 0.04 dpm 1 '. The value of R in the Chukchi Sea averaged 0.36. The average value of accumulation factor of -"Th by particulates in the Bering Sea was 574 ± 63 dpm g ' of dry weight, and 650 ±280 dpm g ' of dry weight in the Chukchi Sea. It is evident that there were considerable variations of C^, within relatively homogeneous water masses and with depth at any given station (Table 3). On one hand, it can be due to the differences in the composition of the suspended matter, in particular the organic matter. This is because the Th accumulation factor in organic matter is some orders of magnitude higher than in inorganic matter (Cherry & Shannon, 1974; Polikarpov era/., 1976). On the other hand, with highly intensive sedimentation processes, the accumulation factors depend on the length of time the particles remain in suspension. TABLE 2 Results of determinations of -"U and -"Th concentrations in seawater and suspended particulates of the Chukchi Sea. Station Latitude Longitude Depth (m) (dpni/l) Ctt, (dpm/1) Date Dissolved Particulate Total 09 Aug 88 45 67°44'N (1 1.73 0.71 0.38 1.09 172°50'W 20 2.38 0.72 0.31 1.03 40 2.39 0.46 0.50 0.96 12 Aug 88 55 67°45'N 0 2.30 0.52 0.49 I.OI 163°26"W 20 2.32 0.38 0.35 0.73 40 2.32 0.42 0.25 0.67 14 Aug 88 69 66°55-N 0 2.30 0.45 0.45 0.90 168°50'W 15 2.30 0.23 0.11 0.34 35 2.30 0.20 0.35 0.55 TABLE 3 POM and -"Th concentrations in particulate matter of the Bering and Chukchi Seas. Station Depth Particulate organic -"Th activity -"Th activity in (m) matter in solution particulate organic (mg dry wt/m') (dpm/1) matter (dpni/g dry wt) 3 0 1,800 391 217 20 704 387 550 40 767 622 811 80 1.365 491 360 7 0 1,545 487 315 45 0 130 368 2,850 20 1,380 1,173 850 40 623 336 540 55 0 1,250 575 460 20 2,776 411 148 40 1,490 209 140 69 0 1,140 593 520 15 1,690 150 89 35 1,815 485 267 89 0 439 206 470 20 1,846 591 320 40 1,090 310 284 100 0 477 430 902 15 1,040 514 494 30 910 592 650 no 0 774 636 822 20 1,700 410 241 50 1,140 935 820 170 630 542 860 113 0 725 716 988 20 586 381 650 227 Our calculations showed that in the Bering and Chukchi Seas the correlation factor between C^ and the residence time of "■"Th, T-^ in various water layers was high, r = 0.86 (n = 26). The data gathered for -'*U and -'""Th concentrations in seawater made it possible to estimate the following biosedimentation parameters: — rate of biosedimentation at specific depths; — the POM concentrations; and — the residence time of POM in the water column. These results are presented in Tables 4 and 5, and in Fig. 1. The biosedimentation parameters varied considerably within the region studied. This was due both to the specific hydrody namic conditions found and to the structural and functional features of the ecological systems under study. In the Bering Sea, the biosedimentation rate was 46.5 ± 5.3 mg dry weight m ' d ' with an average POM concentration of 0.98 ± 0.04 mg dry weight m \ The average residence time of POM in the water column was about one month (29.7 ± 2.9 days). Within the Bering Sea, different regions had highly varied biosedimentation rates. In the Gulf of Anadyr, the biosedimentation parameters had the lowest values. The rate of biosedimentation ranged from 12.0 to 30.0 mg dry wt m' d '. POM concentration averaged 0.86 ± 0.05 g dry wt m ' (n = 9) and, as a rule, did not exceed l.Ogdry wt/m'. The residence time of POM ranged from 16.5 to 26. 1 days at 80-1 20 m depth, and up to 53.3-65.2 days in the euphotic zone. In the region north of St. Lawrence Island, the biosedimentation parameters featured a relative evenness in their vertical profiles. The biosedimentation rate amounted to 110.4mgdry wtm'd' at some depths and high concentrations of POM, more than 1 .0 g dry wt m \ were found throughout the water column. These are approximately the same values observed in the open sea. However, in this region significant changes in the vertical profiles of the biosedimentation parameters were noted. The maximum rates of POM removal were noted above the thermocline at 20-m depth. TABLE 4 Biosedimentation parameters in the Bering Sea. Station Depth Biosedimentation Particulate Residence (m) Rate Organic Matter Time (mg d.w. m ' d ') (gd.w. m') (days) 3 0 76.0 1.12 14.8 20 56.1 1.09 19.4 40 43.8 1.03 23.5 80 97.8 1.23 12.6 7 0 25.5 0.89 35.1 40 22.2 0.86 38.6 80 24.5 0.89 36.3 120 70.0 1.16 16.5 22 0 29.7 0.90 30.4 20 13.5 0.72 53.3 40 10.4 0.68 65.2 80 40.6 1.02 25.1 35 0 22.7 0.83 36.1 20 18.5 0.79 42.8 40 29.4 0.91 31.0 60 12.6 0.72 57.2 89 0 45.2 1.01 22.3 20 87.5 1.18 13.5 40 60.3 1.10 18.2 100 0 110.4 1.22 11.0 15 50.0 1.04 20.8 30 17.4 0.80 45.9 110 0 40.0 1.01 25.3 20 107.3 1.25 11.7 50 34.5 0.98 28.4 170 50.2 1.08 21.5 113 0 56.5 1.06 18.7 20 85.8 1.20 13.8 70 9.6 0.67 70.5 228 In the Chukchi Sea, the biosedimentation rate and particulate concentration were considerably higher values than those in the Bering Sea and averaged 85.0 ± 22.1 mg dry wt m ' d ' and 1.28 + 0.06 g dry wt m \ respectively. Maximum biosedimentation rates for this region occurred below the thermocline. The residence time of the POM in the water column averaged 23 ± 5 days in the Chukchi Sea. The vertical POM profile showed an increased concentration in the 15^0 m layer as compared with the surface waters. The high values of POM and high rates of biosedimentation were evidently due to the phytoplankton bloom observed during the investigation. The bloom achieved red tide proportions at certain stations in the Chukchi Sea. The POM concentrations as a whole matched the spatial distributions of the average biosedimentation rates (Table 6). The values of suspended organic matter for the regions investigated, as a whole, repeated the regularities of spatial distribution exhibited by the average biosedimentation rates (Table 6). In the Bering Sea, the minimum biosedimentation rates from the upper40-m layer were observed in the Gulf of Anadyr, 670-950 mg dry wt m ' d ' . The POM fluxes were much higher in the shallow northern Bering Sea, 1,630-2,800 mg dry wt m- d ', and in the open sea, 2,320- 3,130 mg dry wt m" d '. The average values of the biosedimentation parameters for the upper layer (0-40 m) of the Bering Sea were as follows: the POM flux was 1940 ± 410 mg dry wt m- d ', the POM concentration was 52.6 ± 2.4 g dry wt m -, and the residence time of POM was 19.5 ± 7.4 days. It should be noted that biosedimentation rates vary considerably in different parts of the sea. Near the coasts of the Chukchi Peninsula and Alaska, the sedimentation fluxes from the euphotic layer were the same as in the open and "prestrait" Bering Sea. In the central part of the Chukchi Sea, where the phytoplankton bloom was most intense, the POM flux increased to 5.9 g dry wt m- d '. This assessment of biosedimentation in the Bering and Chukchi Seas points to the high intensity of these processes. This is related to high productivity of the region — principally, to the high rate of organic matter formation in the subarctic and arctic zones of the World Ocean in summer. TABLE 5 Biosedimentation parameters in the Chukchi Sea. Station Depth Biosedimentation Partic ulate Residence (m) Rate Organic Matter Time (mg d.w. m d') (gd.w. m-) (days) 45 0 14.6 0.86 59.2 20 48.3 28 26.3 40 56.0 31 23.3 55 0 45.3 23 27.2 20 83.2 39 16.0 40 95.5 35 14.1 69 0 56.5 26 22.4 15 239.8 44 6.0 35 125.8 37 10.9 229 Slalioii TABLK 6 The average values of the bioscdimentation parameters for the upper layer (0-40 m) of the Bering and Chukchi Seas. Bering Sea Flux of POM POM (mg d.w. Concentration m- d ') (g d.w. m-) Residence Time (days) 3 2,.319 43.4 IH.7 7 948 35 .36.9 22 671 30.2 4.5.0 35 891 33.2 37.2 89 2.80.'S 44.7 15.9 100* 1 ,626 30.0 18.4 110 3,133 46.7 14.9 113 2,834 44.4 15.7 mean 1,940 ±4 10 39.7 ± 2.5 Chukchi Sea 26.3 ± 4.9 Station 1-lux of POM Residence POM (nig d.w Concentration Titne m'd') (g d.w. Ill ') (days) CHUKCHI SEA CHUKCHI PENINSULA BERING SEA Fig. lb ThebiosedimentalfluxesofthePOM (mgd.w.m -d ' ) from the upper layer (0-40 m) of the Bering Sea 45 55 69" mean 1.712 3,073 5,878 3,550 + 250 56.9 52.4 48.5 52.5 + 2.4 33.2 17.0 8.3 19.5 ±7.4 * 0-30 m layer ** 0-35 111 layer BERING SEA CHUKCHI SEA l-lg. le, Thebiosedinienlal nii.xcs of (he POM (mgd.w.m 'd ' ) from the upper layer (0-40 in) ol the Chiikehi Sea Fig. la. The bii>.\e(Jiniental Oiixesoflhe P(^M (mgd.w.m -d ' ) from the upper layer (0-40 m) cil the Benng Sea 230 6.4 Humic Acids IRINA V. PHRSHINA Institute of Global CUimilc and Ecology, State Committee for Hydroineteoroloi^v and Academy of Sciences, Moscow, USSR Introduction The bulk ofthc dissolved organic mnller in natural waters, which is resistant to biochemical degradation, consists of brown, heterogeneous polymers known as humic acids ( U A"s). These substances ticcount lor about 30-60';^ of the total dissolved organic carbon (DOC) in scawaler (Sluermer & Payne, 197.5; Paxeus, 1985). In oceanic areas unaf'tected by freshwater runoff, humic acids are mostly a by-product of algal cell degradation (Harvey etal.. 1988). The concentration of humic acids in seawater is, therefore, related to primary productivity of a region. Recent investigations (Carder el al., 1986, 1989) have shown that phytoplankton and marine humus are only weakly covariant. However, this lack of correspondence is perhaps due to significantly longer residence times for marine humic substances ( Bordovski & I vanenkov, 1 979) relative to the algal population that produced it and the quite variable Hushing and mixing rates for different regions. For this reason pools of marine humus could be indicators of past primary productivity that is not manifested in the present values of productivity and chlorophyll content of the area under consideration. Especially significant correlations between these two parameters could be expected in the highly productive regions such as the Bering and Chukchi Seas. Materials and Methods Collection and Extraction of Seawater .Seawater was collected at depths from 0^ 20 m with a pumping system "Midiya" (Glebov et al.. Subchapter 6..^, this volume). Seawater was pumped through the system of parallel filters (0.5|im pore size membrane) to remove particulate matter, and the filtrate collected in 10-12 plastic vessels (35 liter capacity). When each vessel was full, 70 ml of concentrated HCl was added to it. The acidified seawater (pH 2) was passed through two 1.5 x 15-cm glass columns containing 50 cm' of Amberlite XAD-2 resin at a flow rate of 2 l/h per column. Each column extracted 200-250 1 of seawater in each 48 h. Prior to use, the resin was cleaned as described by Gomez-Belinchon et al. (1988). Isolation of the E.xtracted Humic Acids Columns were first rinsed with 5 6 I of distilled water to remove salts. The collected HA's were elutcd with 500 ml of concentrated NH, solution. To prepare the columns for reuse, they were then eluted with acetone (500 ml), ethanol (800 ml ), and distilled water (8-9 1 ). The regenerated resin was then used to extract the next portion of seawater. The ammonia cluent was concentrated to dryness in a rotary evaporator. The crude HA's were dried in a desiccator over P^O,. Samplini^ I'rocedure for llwirometric Analysis The samples of natural water were taken with a 5- 1 Niskin bottle from the standard depths within the photic /.one (Table 1). The samples were stored in 100-200 ml glass bottles at about -5°C. Apparatus Infrared (IR) spectra were recorded on an UR-20 instrument (GDR). Ultraviolet (UV) spectra were recorded on a Hitachi spectrophotometer, model 100-60. Quart/cells with I cm path length were used. Fluorescence spectra (excitation and emission spectra) were recorded on Jasko spcctrofluorimetcr, inodel SP 240. Excitation and emission spectra were collected with 1 0-nm slit widths I'or both monochromators. Spectra were not corrected for wavelength dependence of monochromator throughout or PMT response. For all fluorescence measurements, 1 -cm path length quart/ cells were used. Chemicals All chemicals were of analytical grade. Preparation of the Standards An aliquot amount of the dried HA (-20 mg) was weighted and redissolved in distilled water (-20 ml). The aqueous HA solution was filtered to remove insoluble residue and added with distilled water to 25 ml. The insoluble residue was dried and weighed. Concentration of the stock solution of HA's was determined by subtraction of the weight of the dry residue from the initial aliquot amount of the HA samples. Calibration Curve Technique The prepared stock solutions were used to plot the calibration curves. Standard solutions were excited at 3 1 5 nm and emission spectra were recorded from 350 to 500 nm. The relative intensity of the standard solution was registered at the maximum of emission spectra and plotted against the concentration. The plot of relative intensity versus the concentration showed a linear relationship from at least 0. 1 ppm up to 20 ppm. This straight line relationship was valid forall of the standard curves. Obtained calibration curves were used for evaluating the concentration of humic acids in the seawater samples. 231 TABLE 1 Concentration (mg/1) of humic acids in the Bering and Chukchi Seas. Bering Sea Depth (m) T 41 89 100 Statio 102 ns no 111 112 113 0 0.3 0.3 1.9 0.8 0.8 0.6 0.5 0.6 0.4 5 0.9 0.5 0.9 0.7 0.9 1.2 0.3 0.6 1.0 10 1.0 0.8 1.4 0.7 0.9 0.4 0.3 0.7 0.6 15 0.9 0.3 1.2 0.7 0.9 0.4 1.2 0.7 0.5 25 2.5 0.3 1.3 0.8 0.8 0.6 0.5 0.5 0.4 45 0.4 0.9 Gl 0.7 If of Anadyr I.O 0.5 0.8 0.5 0.4 Depth (m) 15 19 ->-> 23 Station 26 27 28 29 0 0.1 0.2 0.2 0.1 1.0 0.8 O.I O.I 5 0.1 0.1 0.1 0.1 1.0 0.4 0.2 O.I 10 O.I 0.2 0.2 0.2 0.9 0.7 0.1 0.2 15 0.1 0.3 0.3 O.I 0.5 0.5 O.I O.I 25 0.1 0.3 0.5 0.4 0.8 0.7 0.2 0.2 45 0.2 0.7 Bering Strait 0.8 1.4 0.3 O.I Depth (m) 76 77 Stations 80 83 0 2.0 2.5 1.5 2.7 5 1.8 1.9 1.7 1.4 10 1.4 2.0 1.5 1.6 15 1.6 2.7 1.3 1.6 25 2.1 1.8 1.7 3.1 45 2.3 2.0 1.2 3.0 Chukch Sea Depth (m) 45 49 50 53 Stations 55 57 59 61 63 69 74 75 0 0.2 0.5 1.3 3.5 0.4 1.0 0.6 0.3 1.3 0.2 0,7 0.8 5 0.4 0.6 0.4 1.0 0.4 0.3 0.6 3.1 0.5 0.4 0.5 0.6 10 0.8 0.8 0.3 1.0 0.8 0.3 0.8 0.6 0.8 1.1 1.1 0.9 15 0.8 0.4 0.3 0.7 0.8 0.4 1.8 1.1 0.5 1.1 3.1 1.8 25 0.4 0.5 0.6 0.5 0.5 0.6 2.0 1.1 0.7 1.5 3.1 1.6 45 .07 0.6 1.1 0.5 1.4 0.6 1.6 0.5 2.5 1.2 1.8 1.2 232 Results and Discussion Three samples of HA's were isolated from seawater that was collected at Stations (50+53) and (69+74) in the Chukchi Sea and at Station 1 12 in the Bering Sea. They were characterized by the elemental analysis and spectroscopic studies. Elemental Analysis The results of elemental analysis of the HA samples are summarized in Table 2. TABLE 2 Elemental analysis of Humic Acids. Sample Station %C %H %0 %S %Ash HA-1 50+53 36.0 9.6 52.1 1.3 1.0 HA-2 69+74 35.4 9.8 51.2 1.6 2.1 HA-3 112 36.9 8.0 53.1 N.D. 2.0 As can be seen from Table 2, the humic materials are characterized by the high oxygen content (51-53%). which is typical for marine HA in general (Brown, 1987; Alberts et al., 1988). The presence of sulphur may indicate the presence of lignosulphonic acids (more or less biochemically degraded), which are one of the precursors of humic acids. As a whole, the humic materials isolated from the rather different environments show many similarities in elemental composition. Spectroscopic Studies The IR spectra of the HA studied are rather similar (Fig. 1 ). The broad band at about 3,400 cm ' and the inflection at about 2.600 cm ' are attributed to O-H stretching. The bands at 2,990 cm ' and 2,970 cm ' are due to C-H stretching. Carbonyl stretching gives rise to bands at 1,620 cm ' (conjugated C = 0). Signals from aromatic nuclei (skeletal vibrations) probably both contribute to the latter band and are also responsible for the band at 1,470 cm'. The complex band at about 1 , 1 20 cm ' presumably is due to C-O stretching of phenols and alcohols. A fairly well defined band at 980 cm ' is primarily attributed to aromatic C-H in-plane deformation. Finally, it should be pointed out that obtained IR spectra exhibited strong similarities in general appearance with those obtained by Paxeus ( 1985) and Dereppe et al. (1980). LU O z < z < QC 4000 3000 2000 1600 1200 800 Fig. I. IR-spectra of tlie isolated samples of humic acid. D, cm -1 Ultraviolet and Fluorescence Spectra The UV spectra of the HA samples are shown in Fig. 2. The spectra of aqueous solutions of HA do not exhibit characteristics bands except for the shoulders at 210-230 nm. The fluorescence spectra of the HA samples are shown in Fig. 3. The spectra show one broad band in the excitation spectrum (310-330 nm) as well as in the emission spectrum (400-420 nm). The fluorescence spectra of the HA agree with those obtained by Hayase and Tsubota (1983) and Cabaniss and Shuman( 1987). The pH-dependence of fluorescence intensity of the HA is complex (Fig. 4). Fluorescence intensity is the highest at pH values of 4-5. Decreases in the pH from 4 to 2 are followed by a fall in fluorescence intensity by 5-10%. Raising the pH value to 7.0-7.5 leads to a decrease in the intensity by 15-20%. Further increase in pH value does not affect the fluorescence intensity. LU O Z < CO DC o m < HA-2 HA-1 .HA-3 200 250 300 350 Fig. 2. UV-spectra of the isolated samples of humic acids. X, nm EXCITATION HA! EMISSION 200 250 300 350 400 450 1, nm Fig. 3. Fluorescence spectra of the isolated HA samples. 233 u 2 ttJ U W O HA-1 PH Fig. 4. pH-dependence of fluorescence intensity of the isolated HA samples. Calibration Cun-esfor the Isolated HA Samples The equations for the caUbration curves were determined by hnear least-squares fit. They are presented below. 1(1 ) = (30.0 ± 0.3) X C( 1 ) + ( 16.0 ± 0.2) 1(2} = (44.4 ± 0.2) X C(2) + ( 16.2 ± 0.2) 1(3) = (45.6 ± 0.2) X C(3) + ( 16.0 ± 0.2) Where / is the fluorescence intensity in relative units, C is concentration of HA in ppm, and the standard deviation (SD) for the method is 0.25 ppm (p = 0.05 and N = 6). It is clear from the given equations that both samples from the Chukchi Sea show practically the same calibration curves. This fact is very important. It leads to the conclusion that an HA sample isolated from a local area could be used as a standard for the whole basin. At least, this conclusion could be drawn for moderately sized regions such as the Chukchi Sea. water of the Bering Strait and Chukchi Sea was 1 .25 ppm near the surface and 0.85 ppm in the bottom water. In the present study the concentration of HA's in the surface water of the Bering Strait was 2.6 ppm and 1.8 ppm in the bottom water. Taking into consideration that HA's consist of 40-50% of carbon, the results from this study agree with the Loder's data on DOC distribution. The local HA maxima (30^0 g m - or 0.6-0.8 ppm) were found at Stations 26 and 27 (the Gulf of Anadyr), and Stations 100 and 102 (the Bering Sea Shelf). Other areas of the Bering Sea and the Gulf of Anadyr that were studied were characterized by an average value of HA concentration 20-22 g m - or 0.3-0.5 ppm. The distribution described here of HA was compared with the distribution of nutrients, chlorophyll a, and primary production in the same regions (Grebmeier, Subchapter 7.1; Korsak. Subchapter 6. 1 ; Whitledge. Subchapter 3. 1 ; Zeeman, Subchapter 6.2, this volume). Direct correlation between the parameters was not found. However, the comparison did point out that the highest HA concentration was found between the two maxima in primary production at Stations 36 and 53 (Zeeman, Subchapter 6.2, this volume) and behind the front of chlorophyll a in the Chukchi Sea (Whitledge. Subchapter 6.2; Grebmeier, Subchapter 7.1, this volume). To explain the observed relationships between distribution of primary production, chlorophyll a and HA, the following factors should be taken into consideration. First, the HA pool can be considered as a by-product of primary productivity. It is synthesized as a result of decay of newly produced organic matter and dead algal cells. However, there are great differences in the half-lives of humus relative to the algal population which produced it. When a phytoplankton bloom is transported offshore or northward and is grazed and degraded, the synthesis and accumulation of HA's goes on. This creates a lag between primary production and the HA concentration. Recent studies Fhtorimetric Determination of Hitmic Acids in the Seawater Samples Humic acid concentration in the seawater samples was determined as described in Pershina (1987) using calibration curve technique. The data are summarized in Table 2 and shown in Fig. 5. In considering the current results, the following main items could be pointed out. The highest concentration of HA's (75-80gm-or 1.8-2.2 ppm) was detected in the region of the Bering Strait (Stations 76, 77, and 83) and adjacent edge of the Chukchi Sea (Station 74). High concentration of HA (60-70 g m- or 1.6-1.7 ppm) was found in the northern edge of the Bering Sea Shelf (Station 89) and in the southern part of the Chukchi Sea (Station 69). Relatively high contents of humic substances (30-50 g m - or 1 .0- 1 .4 ppm ) were observed in practically the whole area of the Chukchi Sea except for the northwestern region adjacent to the East Siberian Sea (Station 45) ( 16 g m - or 0.4 ppm). These results from the Chukchi Sea agree with the previous study on the DOC distribution in Alaskan polar, subpolar, and estuarine waters (Loder. 1971; Hood & Reeburgh. 1974). In this study, the average concentration of DOC in the surface Fig. .S. Depth-integrated distribution of humic acids (g ni -). 234 on the effects of HA" s on remote sensing of ocean chlorophyll (Carder et al.. 1 986, 1 989) have shown that the lag time could be one or two months. Second, the accumulation and distribution of HA's is dependent to a great extent on the mixing and flushing rates for the region. A reduction in the Hushing or mixing rates should allow degradation products to accumulate relative to a well flushed environment. Therefore a bay or stagnant gyre should have more HA per unit of chlorophyll or newly produced organic matter than would a recently upwelled phytoplankton bloom. While considering the present results (Fig. 4) it should be stressed that the highest HA concentration is found in the region of the Bering Strait. According to Coachman ( 1 986) the water passing through the strait has three major components. In the west, the tlow is dominated by cold, saline water from the Gulf of Anadyr. In the east, the flow consists of warmer coastal water dominated by the Yukon River discharge. South of St. Lawrence Island, a third water mass is formed of modified shelf water. The Bering Shelf-Anadyr water in the west and the Alaskan Coastal-Yukon River water in the east maintain their identity during passage through the strait. The nutrient-laden western Bering Strait tlow is associated with a large standing crop of phytoplankton (Sambrotto et al.. 1984). It could be one of the main factors contributing to the local HA maximum. In addition, constant inflow of the degradation products from the highly productive waters could promote the synthesis and accumulation of HA's in the strait region as well. These sources include the Gulf of Anadyr, the Bering Sea Shelf, and the coast of Alaska. The lag of HA's behind the chlorophyll distribution and primary production value could be responsible for the observed HA maximum in the southern Chukchi Sea. The local HA maximum at Stations 26 and 27 in the Gulf of Anadyr and at Station 1 02 on the Bering Sea Shelf appears to be connected with the freshwater discharges of the Anadyr River and the Yukon River. The results showing the high HA distribution in the Chukchi and Bering Seas could be considered as the confirmation of high productivity in the region. Taking into consideration the long half-lives of HA's, the HA concentration may be used, in a limited sense, as a quasi- conservative water mass property. Humic acid pools may be interpreted as a measure of primary productivity of a region over the previous one or two months. For this approach to be useful, a better understanding of degradation rates from dead algal cells and newly produced organic matter to HA's is required. In addition, we need to understand the effects of flushing, mixing, and photolysis on the degradation products. Even without these more intense studies, a certain degree of accuracy can be expected from empirical studies of primary productivity and HA's. 235 236 Chapter 6 References Aagaard, K., Swift, J. H. & Carmack, E. C. (1985). Thermeihaline circulation in the Arctic-Mediterranean seas. J. Geophys. Res. 90, 4833^846. Alberts, J. J., Filip, Z., Price, M. T., Williams. D. J. & Williams, M. C. (1988). Elemental composition, stable carbon isotope rating and spectrophotometric properties of humic substances occurring in a salt marsh estuary. Org. Geochem. 8, 455-467. Alton, M. S. (1974). Bering Sea benthos as a food source for demersal fish populations. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelly, eds. ), pp. 257-277, Institute of Marine Science, University of Alaska, Fairbanks. Anderson, L. G., Dyrssen, D. & Jones, E. P. (1990). An assessment of the transport of atmospheric CO, into the Arctic Ocean. / Geophys. Res. 95(C2), 1703-171 1. Barinov, G. V., Blinov, M. V. & Gritchenko, Z. G. (1967). Natural radionuclides accumulation by seaweeds and plankton in the Ocean. Hydrophysical Investigations of the Pacific and Atlantic Oceans during Circumnavigation of the World by the "Michail Lomonosov " Scientific - Research Ship (20 voyages). Sebastopol, published by the Sea Hydrophysical Institute of the UkSSR Academy of Sciences, pp. 32-37. (in Russian) Bhat S. G., Krishnaswame, S., Lai, B. & Moore, W. S. ( 1969). -"Th/^"*U ratios in the ocean. Earth Planet. Sci. Lett. 5, 483-491. Bordovski, O. K. & Ivanenkov, V. N. (eds. ) (1979). Ocean Chemistry, Vol. 1 . Chemistry of Seawater, pp. 277-279. Nauka Publishers, Moscow, (in Russian) Brewer, P. G., Goyet, C. & Dyrssen, D. ( 1 989 ). Carbon dioxide transport by ocean currents at 25°N latitude in the Atlantic Ocean. Science 246, 477-479. Brown, J. W. ( 1987). Studies of huniic and full acid dynamics in coastal marine waters of South Florida. Mar. Environ. Re.'i. 21, 168-174. Cabaniss, S. E. & Shuman, M. S. (1987). Synchronous fluorescence spectra of natural waters: Tracing sources of dissolved organic matter. Mar Cheni. 21, 27-50. Carder, K. L., Stewart, R. G., Harvey, G. R. & Arter, P. B. (1989). Marine humic and fulvic acids: Their effects on remote sensing of ocean chlorophyll. Limnol. Oceanogr. 84. Carder, K. L., Stewart, R. G., Paul, J. H. & Vargo, G. A. (1986). Relationships between chlorophyll and ocean color constituents as they affect remote sensing reflectance models. Limnol. Oceanogr. 31,403-418. Cherry R. B. & Shannon, L. V. ( 1974). The alpha radioactivity of marine organisms. Atom. Energy Rev. 12( 1 ), 3^5. Coachman. L. K. (1986). Circulation of water masses in the Bering Sea shelf. Cont. Shelf Res. 5, 28-101. Coale K. H. & Bruland, K. W. (1987). Oceanic stratified euphotic zone as elucidated by -"Th:-"*U disequilibrium. Limnol. Oceanogr. 32(1), 129-200. Dereppe, J. M.,Moreaux,C. &Debyser,G. (1980). Investigation of marine and terrestrial humic substances by IH and 13C, nuclear magnetic resonance and infrared spectroscopy. Org. Geochem. 2, 117-124. Favorite, F. ( 1 974). Flow into the Bering Sea through Aleutian Island passes. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelly, eds. ), pp. 3-37, Institute of Marine Science, University of Alaska, Fairbanks. Gomez-Belinchon, J. I., Grimalt, J. O. & Albages, J. (1988). Intercomparison study of liquid-liquid extraction and absorption on polyurethane and Amberlite XAD 2 for the analysis of hydrocarbons, polychlorobiphenyls, and fatty acids dissolved in seawater. Environ. Sci. Technol. 22, 877-885. Grebmeier, J. M., Feder, H. M. & McRoy, C. P. (1989). Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. III. Benthic food supply and carbon cycling. Mar. Ecol. Prog. Sen 53, 79-91. Grebmeier, J. M., McRoy, C. P. & Feder. H. M. (1988). Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. I. Food supply source and benthic biomass. Mar. Ecol. Prog. Ser. 48, 51-61 . Harvey, G. R., Boron, D. A., Chesal, L. A. & Tokar, J. M. (1983). The structure of marine fulvic and humic acids. Mar. Chem. 12, 119-132. Hayase, K. & Tsubota, H. ( 1 985 ). Sedimentary humic acid and fulvic acid as fluorescent organic materials. Geochim. Cosmochim. Acta. 40, 159-168. Hood, D. W. & Kelly, E. J. (1974). Introduction. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelly, eds. ), pp. xv-xxi. Institute of Marine Science, University of Alaska, Fairbanks. Hood, D. W. & Reeburgh, W. S. (1974). Chemistry of the Bering Sea: An overview. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelly, eds. ). pp. 191-204, University of Alaska, Fairbanks. Izrael, Yu. A. & Tsyban, A. V. ( 198 1 ). Problems of Monitoring the Ecological Consequences of Ocean Pollution. Leningrad, (in Russian) Jassby, A. D. & Piatt, T. (1976). Mathematical formulation of the relationship between photosynthesis and light for phytoplankton. Limnol. Oceanogr. 21, 540-547. Koblentz-Mishke, 0. J., Volkovinsky, V. V. & Kabanova, J. G. (1970). Plankton primary production ofthe World Ocean. In Scientific Exploration ofthe South Pacific. Standard Book No. 309-01755-6, pp. 183-193. National Academy of Sciences, Washington, D.C. Koike, I., Furuya, K., Otobe, H., Nakai, T., Nemoto, T. & Hattori, A. (1982). Horizontal distributions of surface chlorophyll a and nitrogenous nutrients near Bering Strait and Unimak Pass. Deep-Sea Res. 29, 149-155. 237 Korsak. M. N. (1982). Characteristics of regeneration of organic matter in the Bering Sea. In Proceedings of the Second AU-Union Conference ofOceanologists, No. 5. Korsak, M. N. (1985). Results of a study of the state of the Bering Sea plankton community. In Ecological Consequences of Ocean Pollution, pp. 56-67. Gidrometeoizdat Publishers, Leningrad, (in Russian) Ku, T. H., Knauss, K. G. & Matheiu, G. C. (1977). Uranium in the open ocean concentration and isotopic composition. Deep-Sea Res. 24, 13-26. Lisitsyn, A. P. ( 1983). Biodifferentiation in Seas and Oceans. pp. 3-9. Published by Institute of Oceanography, Academy of Sciences, (in Russian) Loder, T. C. ( 1 97 1 ). Distribution of Dissolved and Particulate Organic Carbon in Alaskan Polar, Subpolar and Estuarine Waters. Ph. D. thesis. University of Alaska, Fairbanks (Cited in Hood & Reeburgh, 1974). Matsumoto, E. ( 1975). -'"'Th--"*U radioactive disequilibrium in the surface layer of the ocean. Geochim. Cosinochim. Acta 39,205-212. McKee B. A., DeMaster, D. J. & Nittrouer, C. A. ( 1984). The use of -'''Th/-"*U disequilibrium to examine the fate of particle-reactive species on the Yangtze continental shelf. Earth Planet. Sci. Lett. 68, 431-M2. Nasu, K. (1974). Movement of baleen whales in relation to hydrographic conditions in the northern part of the Bering Sea. In Oceanography of the Bering Sea (D. W. Hood & E. J. Kelly, eds. ), pp. 345-361, Institute of Marine Science. University of Alaska, Fairbanks. Ohtani, K. (1969). On the oceanographic structure and the ice fomiation on the continental shelf in the eastern Bering Sea. Bull. Fac. Fi.sh.. Hokkaido Univ. 20(2), 94-1 17. Paxeus, N. ( 1 985 ). Studies on Acjuatic Humic Substances, Ph. D. Thesis, University of Gotenburg, Sweden. Pershina, I. V. (1987). Determination of Fulvic Acids in Natural Waters. Ph. D. thesis, Moscow State University, USSR, (in Russian) Piatt, T., Gallegos, C. L. & Harrison, W. G. (1980). Photoinhibition of photosynthesis in natural assemblages of marine phytoplankton. J. Mar. Res. 38, 687-701. Polikarpov, G. G. & Yogorov, V. N. ( 1980). The ability of sea ecosystems to remove radioactive and chemical pollutants from the photic layer. Bulletin of the USSR Academy of Sciences 12, 80-96. (in Russian) Polikarpov, G. G., Zesenko, A. Ya., Yegorov, M. N. & Nazarov, A. B. (1976). Application of radioisotope methods in investigating production processes and dynamics of organic substance in the ocean. Sea Hydrophysical Investigations 74(3), 116-124. (in Russian) Pomeroy, L. R. & Deibel. D. (1986). Temperature regulation of bacterial activity during the spring bloom in Newfoundland coastal waters. Science 233, 359-361. Sambrotto R. N., Goering J. J. & McRoy C. P. (1984). Large yearly production of phytoplankton in the western Bering Strait. Science 225. 1147-1150. Sambrotto, R. N., Niebauer, H. J., Goering, J. J. & Iverson, R. L. (1986). Relationships among vertical mixing, nitrate uptake, and phytoplankton growth during the spring bloom in the southeastern Bering Sea middle shelf. Cont. Shelf Res. 5, 161-198. Sorokin, Yu. 1.(1 973 ). Primary production of seas and oceans. Advances in science and technology. General Ecology. Biocenology and Hydrobiology, Vol. 1, VINITI, Moscow, (in Russian) Sorokin, Yu. 1., Korsak, M. N., Mamaeva, T. I. & Kogelshats, D. G. (1983). Primary production and activity of the microflora in regions of the Peruvian upwelling. Bioproductivity of Ecosystems of Upwellings, pp. 74-87, Moscow, (in Russian) Strickland, J. D. H. & Parsons, T. R, (1972). A Practical HandbookofSeawater Analysis. Second edition, F/i^/;. Res. Board Can. Bull. 167. Stuemier, D. H. & Payne, J. R, (1975). Investigation of seawater and terrestrial humic substances with carbon-B and proton nuclear magnetic resonance. Geochim. Cosmochim. Acta 19, 1 109-1 1 14. Sverdrup, H. U., Johnson, M. W. & Fleming, R. H. ( 1942). The Oceans: Their Physics, Chemistiy, and Biology. Prentice- Hall, Englewood Cliffs. 1060 pp. Swift, J. H. & Koltermann, K. P. (1988). The origin of Norwegian Sea deep water. J. Geophxs. Res. 93, 3563- 3569. Takenouti. A. Y. & Ohtani, K. (1974). Currents and water masses in the Bering Sea: A review of Japanese work. In Oceanography of the Bering Sea (D. W, Hood & E. J. Kelly, eds. ), pp. 39-57, Institute of Marine Science, University of Alaska, Fairbanks. Tsyban, A. V. ( 1 985 ). Main results of ecological studies of the pelagial of the Bering Sea and northern Pacific Ocean. In Ecological Consequences of Ocean Pollution, pp. 25-36. Gidrometeoizdat Publishers, Leningrad, (in Russian) Tsyban, A. V., Korsak, M. N., Volodkovich, A. V. & McLaflin, D. D. (1985). Ecological studies in the Bering Sea. In Comprehensive Global Monitoring of the Ocean, pp. 140-163. First International Symposium, Vol. I.Moscow. (in Russian) Turekian, K. K. & Chan, L. M. ( 1 97 1 ). The marine geochemistry of the uranium isotopes -"Th and -" Pa. In A t7/v«;/()); A/!fl/v,s« in Geochemistry and Cosmochemistiy. University of Storiaget, pp. 311-320. Vakulovsky, S. M, (ed, ) ( 1986). Recommended Methods for Determining Radioactive Pollution in Water Resources. Gidrometeoizdat Publishers. Moscow, (in Russian) Walsh. J. J.. Premuzic, E. T., Gaffney, J. S,, Rowe, G. T., Hardbottle, G., Stoener, R, W., Balsam. W. L., Betzer, P. R. & Macko, S. A. (1985). Organic storage of CO, on the continental slope off the mid-Atlantic Bight, the southeastern Bering Sea and the Peru coast. Deep-Sea Res. 32,853-883. Walsh. J. J,, McRoy, C. P,, Coachman, L. K., Goering, J. J., Nihoul, J. J., Whitledge, T. E., Blackburn, T, H., Parker, P. L., Wirick. C, D.. Shuert, P. G,, Grebmeier. J. M., Springer, A. M., Tripp, R. D,, Hansen, D., Djenidi, S,. Deleersnyder, E,, Henriksen, K., Lund. B. A.. Andersen, P.. Muller-Karger, F. E. & Dean, K. ( 1989). Carbon and nitrogen cycling within 238 the Bering/Chukchi Seas: source regions for organic matter Whitledge, T. E., Bidigare, R. R., Zeeman, S. I., Sambrotto, R. affecting AOU demands of the Arctic Ocean. fwt;r. N., Roscigno, P. F.Jensen, P. R., Brooks, J. M., Trees, C & Oceanogr. 22,277-359. Veidt, D. M. ( 1988). Biological measurements and related Washburn, A. L. & Weller, G. ( 1986). Arctic research in the chemical features in Soviet and US regions ofthe Bering Sea. national interest. Science 233, 633-639. Cant. Shelf Res. 8( 12), 1299-1320. 239 Chapter 7: BENTHIC PROCESSES & BOTTOM FAUNA Editors: JACQUELINE M. GREBMEIER & YURIY L. VOLODKOVICH 7.1 Benthic Processes on the Shallow Continental Shelf JACQUELINE M. GREBMEIER Graduate Program in Ecology, University of Tennessee. Knoxville, Tennessee, USA Introduction Participation in the Third Joint US-USSR Bering & Chukchi Seas Expedition from 24 July to 3 September 1988 extended studies of pelagic-benthic coupling and benthic carbon cycling in the northern Bering and Chukchi Seas (Grebmeier et al., 1988; 1989; Grebmeier & McRoy, 1989) into Soviet waters previously inaccessible to US scientists. Scientific studies included benthic community structure and biomass, faunal bioturbation, benthic carbon cycling, and carbon accumulation in the sediments. In addition, data were collected and analyzed in cooperation with L. Cooper and M. DeNiro (University of California, Santa Barbara) to investigate a new technique for studying multiyear variation in water mass movement in polar seas using stable oxygen isotope measurements of tunicate cellulose and bottom seawater (Grebmeier et a!.. 1990). The shelf of the northern Bering and Chukchi Seas is shallow (30-70 m) and normally ice-covered from November to May. Northerly-flowing currents transport Pacific Ocean water through Bering Strait into the Chukchi Sea and Arctic Ocean ( Fig. 1 ). Three major water masses develop during the open- water season, each having different salinity, nutrient, and phytopiankton dynamics (Walsh et al.. 1989). The high nutrient load (20-33 |i M NO, -N) of the subsurface Anadyr Water provides a continuous source of nutrients for high primary production in the water column on the west side of the shelf from the Gulf of Anadyr to north of Bering Strait, but nutrient depletion limits production along the Alaska coastline after the spring bloom. Past studies have shown a direct relationship between the particulate organic matter tlux to the benthos and planktonic production in the surface waters of the ocean (Eppley & Peterson. 1979; Deuser et at.. 1981; Davies & Payne, 1984). The quantity and quality of freshly produced or consolidated organic carbon reaching the benthos is influenced by many factors, such as mixed layer and water column depth, zooplankton grazing, and bacterial decomposition in Ihe water column (Parsons ef«/., 1977). Supply of organic matter to the benthos is a major factor influencing benthic community structure, biomass, and metabolism (Mills. 1975; Graf t-r al.. 1982; Jorgensen, 1983; Smith el al.. 1983; Smetacek. 1984; Was.sman, 1984; Grebmeier t-r «/.. 1988. 1989: Grebmeier & McRoy. 1989). Sediment oxygen uptake rates provide information on aerobic utilization of carbon in sediments and have been shown to increase with elevated carbon fluxes to the sediments (Hargrave, 1973; Davies. 1975). Recent studies using shipboard sediment oxygen uptake experiments in the shallow shelf of the northern Bering and Chukchi Seas show the value of this measurement in delineating areas of high organic carbon flux to the benthos, which are coincident with areas of high water column production, benthic faunal biomass, and sediment carbon remineralization (Blackburn, 1987; Grebmeier & McRoy. 1989). These total sediment oxygen uptake rates are used as an indicator of food supply to the benthos. Fig. 1 . Study area in tlie northern Bering and Chukchi Seas showing local water circulations, water ma.sses, and bathymetry (modified from Coachman cfo/., 1975; Walsh « a/.. 1989). Marine benthic systems in polar regions can exhibit high abundance and biomass in spite of cold temperatures and only seasonal pulses of particulate organic matter to the benthos (White. 1977;Stoker. 1978; Petersen & Curtis. 1980; Grebmeier. 1987; Grebmeier& McRoy. 1989). High latitude shelves have a higher percentage of water column production reaching the benthos compared to both tropical and temperate regions, supporting larger benthic populations (Petersen & Curtis. 1980). In eariy spring, food supply to the benthos in the northern Bering and Chukchi Seas consists of ice algal cells, water column phytopiankton, and cells resuspended from the 243 bottom with older detrital material. The work of Coyle and Cooney (1988) indicates that a large portion of the eastern Bering Sea ice-edge bloom is ungrazed by zooplankton and sinks directly to the benthos. These workers also found that a separate zooplankton community on the middle shelf of the southeastern Bering Sea did not graze a significant proportion ofthe spring carbon production (Cooney & Coyle, 1982). Here again, a large percentage of the organic carbon settles to the benthos to support a rich benthic community (Feder et al.. 1980;Feder&Jewett, 1981;Walsh& McRoy, 1986). Likewise, In the northern Bering and Chukchi Seas, a significant portion of the high carbon production in the Bering Shelf and Anadyr waters reaches the benthos, supporting a high benthic biomass of infaunal invertebrates and high sediment carbon mineralization (Grebmeier et al., 1988, 1989; Grebmeier & McRoy, 1989; Walsh et al., 1989). Although sediment grain size composition is the dominant factor in determining benthic community composition on the continental shelf of the Bering and Chukchi Seas (Stoker, 1978; Grebmeier f/fl/., 1989), food supply is the major factor influencing benthic biomass (Grebmeier f/fl/., 1988: Grebmeier & McRoy, 1989). Carbon/nitrogen ratios in surface sediments can provide an indication of the quality of organic material arriving at the sea bottom, although water column nutrient concentration, zooplankton grazing, and bacterial degradation can influence these values (Parsons et al., 1977; Valiela, 1984). Past work has used surface sediment C/N values to separate areas of high and low particulate organic carbon loss to the benthos (Walsh et al.. 1981). Grebmeier el al. (1988) used C/N ratios, in combination with sediment respiration rates, to investigate the quality and quantity of organic material available to benthic populations in the northern Bering and Chukchi Seas. Low surface sediment C/N ratios (5-7 wt./wt.) suggest a higher quality, nitrogen-rich organic material deposition to the benthos under the highly productive Bering Shelf-Anadyr water .(280 g C m - yr '; Walsh et al., 1989), compared with lower quality, higher C/N ratios (8-14 wt./wt.), indicative of less labile, more refractory marine and terrestrial organic matter in the sediment under the less productive Alaska Coastal water (60gCm-yr ';Walshcfa/., 1989). In the southeastern Bering Sea, variations in the cross-shelf distributions of C/N ratios in surface sediments have been attributed to different proportions ofdetritus (Walsh ('/«/.. 1981; Walsh & McRoy, 1986). Lead-210(-"'Pb; half-life = 22.3 yr) is a particle-reactive, naturally-occurring radionuclide produced during the -'"Uranium decay series. Since -"Rn is a nonreactive, noble gas, some escapes to the atmosphere before it decays to -'"Pb, which is then washed out of the atmosphere via precipitation, forming a measurable flux of -'"Pb in excess of that produced solely from ---Rn decay within the water column and sediments. Lead-2 10 rapidly adsorbs onto particulate matter and descends to the bottom sediments. It has been used successfully in both freshwater and marine systems to quantify physical and biogeochemical processes on time scales of months to decades (Krishnaswami et a!., 1980; Walsh, 1988). In sedimentary studies, measures of excess -'"Pb ( - '"Pb-ex) in sediments provide an indicator of sediment accumulation, since -'"Pb concentrations in excess of that supported by decay in the sediments alone indicate accumulation of allocthonous materials. Used coincidently with organic carbon measurements in the sediment, -'"Pb-ex can provide information on sedimentation and accumulation rates of organic carbon in the environment. Stable oxygen isotope composition is normally expressed as '^O/'^O ratios in the standard 5 notation: 5 "<0 = (''standard/'*sample')x 10' 7„,, where R = '"0/"'0 and standard is standard mean ocean water (SMOW). The stable oxygen isotope composition of seawater (5 '"O) varies temporally and spatially in regions of the ocean, such as on shallow continental shelves influenced by freshwater input, which is depleted in the heavier oxygen isotope ('*0), relative to the lighter oxygen isotope ( '"O), particularly at high latitudes where fractionation is intensified (Ferronsky & Polyakov, 1982). Stable oxygen isotope variability in surface marine waters has been used to study oceanic circulation, and when combined with salinity and temperature data — water contributions from rivers, evaporated surface ocean waters, melting glaciers, and melting sea ice, can be separated and water types characterized (Epstein & Mayeda, 1953: Redfield 6 Friedman, 1969; Tan & Strain, 1980; Bedard et al., 1981: Fertonsky & Polyakov, 1982). Salinity is the predominant factor determining seawater density and water mass characteristics in the northern Bering and Chukchi Seas (Coachman et al., 1975). There is a known relationship between '"O content and salinity in ocean waters, with similar processes influencing both salinity and "'O content in tandem (Epstein & Mayeda, 1953: Fen-onsky & Polyakov, 1982). Thus, the major water masses in our study should be distinguishable by both 5 "*0 values and salinity concentrations. However, the salinity-5 ""O relationship can become decoupled when multiple freshwater sources of differing 5 "*0 values mix with saline water, leading to different 5 "O values but similar salinities for the mixtures. Another deviation from the salinity- 5 '"O relationship can occur when sea ice forms and the resultant brine injection increases the underlying waters' salinities but does not significantly change 6 ' '*0 values over the whole water column, although sea ice itself is affected ( Redfield 6 Friedman, 1969; Vetshteyn et al., 1974; Fertonsky & Polyakov, 1982). Thus '"O data can allow tracing of known water mass distributions in polar seas despite changes in salinity over the winter period. Oxygen removed from seawater by organisms reflects oceanic circulation processes in many circumstances. The oxygen isotope composition of cellulose is directly related to the oxygen isotope composition of water available to submerged aquatic plants and to members ofthe marine urochordate class Ascidiacea (tunicates), which synthesize cellulo.se (Epstein et al., 1977: DeNiro & Epstein, 1979, 1981). DeNiro and Epstein (1981) observed that aquatic plant and tunicate cellulose 5 "*0 values were 27 ± 3 "/„o more positive than the 5 "*0 values of the growth media. No significant temperature effects on isotopic fractionation were observed during cellulose synthesis in freshwater plants (DeNiro & Epstein, 1981) or during the carbonyl exchange reactions prior to cellulose synthesis that may govern the fractionation observed (Sternberg & DeNiro, 1983). Although tunicates have not been cultured under 244 different temperature regimes, the similar, consistent differences between the 5 '*0 values of water and tunicate cellulose for tropical and temperate animals that lived at temperatures differing by as much as 1 5°C ( DeNiro & Epstein, 1981) suggest that, as in plants, there is no significant temperature effect on oxygen isotope fractionation in tunicate cellulose. Material and Methods Stable Oxygen Isotope Composition-Seciwater and Tiinicates Bottom seawater for stable oxygen isotope analyses were subsampled in 20-ml vials, capped, sealed with Parafilm, and returned to the laboratory. Oxygen isotope ratios of water samples were determined by equilibrating 1 .0-ml water samples with approximately 300 |i moles of carbon dioxide for 48 hours, purifying the equilibrated carbon dioxide cryogenically, analyzing the CO, mass spectrometrically, and using mass balance considerations to calculate the original oxygen isotope composition of the water (Epstein & Mayeda, 1953). Tunicates were collected from both a 0.1 -m- van Veen grab (weighted with 32 kg of lead for enhanced penetration) and otter trawl. Animals were sorted, keyed to species or lowest taxon possible, and frozen in Whirl-pak bags. In the laboratory, tunicates were freeze-dried and the body wall of solitary animals dissected out for cellulose extraction. In the case of colonial ascidians. a section of the outer region of the animal was excised for extraction. Cellulose was extracted using a sodium chlorite-acetic acid oxidation procedure (Wise, 1944), Oxygen isotope ratios of cellulose were determined by pyrolyzing vacuum-dried and sealed samples in the presence of HgCl, at 520° C for 5 hours to form CO, CO, and HCl. CO was disproportionated to CO, and C by electrical discharge. HCl was removed by reaction with isoquinoline (Epstein et ai. 1977). The CO, was then analyzed mass spectrometrically. Sediment Oxygen Uptake Rates Sediment samples for respiration experiments were collected using a HAPS 0.0 1 33 m^ benthic corer or a box corer. A shipboard core incubation technique for benthic metabolism was used, following methods of Grebmeier and McRoy ( 1989), which are based on experimental techniques of Pamatmat (1971), Newrkla (1983), and Patching and Raine (1983). Subsamples for core incubations were collected with 13-cm diameter, 26-cm long acrylic cores ( 8-mni thick walls). Average sediment depths were 10-15 cm, with the remainder of the core barrel enclosing bottom water. Overlying bottom water was carefully siphoned off and replaced with bottom water collected with a Niskin bottle at the beginning of the experiment. The cores were sealed with air-tight lids. Battery-operated stirrer blades inside the core barrel mixed the water to reduce oxygen gradient formation without disturbing the sedmients (Newrkla, 1983). Control laboratory experiments showed no disturbance of sediment surfaces during stirring nor leakage of oxygen through the container walls (Grebmeier & McRoy, 1989). Cores were maintained in the dark at in situ bottom temperatures for 8- 1 0 hours. This experimental duration has been determined to be adequate for measurable depletion of oxygen (average 25%) in the chambers for similar sediments (Grebmeier & McRoy, 1989). Duplicate 60-ml water samples were collected at the beginning of the experiment from the bottom water Niskin bottle and at the end of the experiment from the sediment cores for determination of dissolved oxygen content by Winkler titration. After completion of the experiment, sediment cores were washed through 1-mm stainless steel screens. Animals were preserved in 10% seawater formalin, buffered with hexamethyltetramine, stored in plastic Whirl- pak bags, and saved for laboratory analy.ses (i.e., identification, abundance counts, and biomass weights). Benthic Faiinal Abundance and Biomass Quantitative benthic samples were taken with the 0.1 m- van Veen grab. Previous work in the Bering Sea (Feder et ai, 1973; Grebmeier, 1987) indicates that 4 grab samples per station are adequate to account for natural statistical variability at each station. Each sample was washed through 1-mm stainless steel screens and animals subsequently preserved in 10% seawater formalin, buffered with hexamethyltetramine, stored in plastic Whirl-pak bags, and saved for laboratory analyses. Animals were keyed to family level, abundance was recorded, then they were blotted dry and weighed to determine wet-weight biomass. Wet-weight values were converted to organic carbon biomass using previously verified conversion values (Stoker, 1978; Grebmeier, 1987). The carbon conversions enable comparison of biomass between stations by reducing the influence of the calcium carbonate tests of mollusks and echinoids on total biomass. Log-transformed abundance data were analyzed using a numerical clustering program to group stations according to faunal similarities (Feder et ai, 1985; Grebmeier era/., 1989). Sediment Characteristics Surface sediment subsamples were taken from the van Veen or Haps/box corer for total organic carbon and nitrogen determinations at each station. Samples were dried at 105°C overnight and homogenized with a mortar and pestle. One- gram subsamples of surface sediment (0-1 cm) were acidified with 2 ml of 1 N HCl and redried at 105°C overnight to obtain carbonate-free sediments, and then rehomogenized. Carbon and nitrogen contents were measured on a CHN analyzer. In addition, sediment subcores were collected at representative stations in each of the main basins, sectioned shipboard into 1-2 cm intervals, frozen, and returned to the laboratory. The concentration of -'"Pb was measured by gamma-spectrometry using low-background, high resolution, germanium detectors equipped with a Nuclear Data Model 990 microprocessor system programmed to record gamma spectra in 4,096 channels. Samples were dried at 105°C overnight, homogenized, and then packed in 90-cm' aluminum cans or 15-cm' plastic Petri dishes, depending on the amount of material available. The detectors were calibrated for the respective geometries with a certified mixed standard and the calibration procedures are described elsewhere (Olsen et ai, 1989). The low-energy (46.5 keV) -'"Pb gamma-ray was analyzed using a planar intrinsic-gennanium detector and correction for self-absorption (Cutshall et al., 1983). This technique allows for direct counting of radioactivity without leaching or radioactive 245 separation and allows for the simultaneous determination of both the total -'"Pb and the -'^Pb-supported level. Excess -'"Pb was calculated by subtracting the -'^Pb-supported level from the total -'"Pb activity. Results and Discussion Stable Oxygen Isotopes of Seawater and Tunicate Cellulose During August 1988, the stable oxygen i.sotope (6 "O) signature values were determined for the major water masses in the northern Bering Sea (Fig. 2). In the northwestern section of the study area, the Anadyr Current (a bifurcation of the Bering Slope Current further south) travels clockwise in the Gulf of Anadyr. Most of this high nutrient, saline water exits northward through Anadyr Strait (Fig. 1), but some of this Anadyr water travels southeast of St. Lawrence Island (Coachman etai, 1975; Walsh etai, 1989) . The 5 ''O value for deep Bering Sea water was -0.8'Voo, while Bering Slope Current water and Anadyr water were -1.2 to -1.3"/(x, and -1.4 to -LS^/ijo, respectively, showing the early stages of freshwater dilution as deep Bering Sea water is advected up onto the shelf (Fig. 2). The cold pool in the Gulf of Anadyr, southwest of St. Lawrence Island, had a 5 '"O value of -2.0'Voo and the Alaska Coastal water to the east had the most depleted 8 "*0 values (-3.0 to -5.0"/,„). This west to east depletion of "O in bottom seawater parallels the west to east decreasing gradient in salinity occurring across the shelf in spring/summer due to freshwater dilution of Bering Sea water (Coachman et ai, 1975: Schumacher et ai, 1983). deep Bering !•) Sea waler (3215 m depth) Bottom water "SMOW Siberian Coastal Waler Gult ol Anadyr waler tronlal station BSW-ACW Alaska Coastal Water Wollstiore Yukon River ll4mdeptri) Bottom water salinity {7oo) Fig. 2. Relation between bottom water '"O values and salinity for stations occupied in the northern Bering and Chukchi Seas in 1987 and 1988. Water masses are defined by both salinity and location (Grebmeier elal. 1990). The Bering Shelf water (BSW) is formed south of St. Lawrence Island in the summer as a mixture of water from the Bering Sea moving northward, mixing with the less saline cold pool of resident water formed in the polynya south of St. Lawrence Island over winter, but it is the least understood water mass in the northern Bering Sea (Coachman etal..\915). 5 "*0 values for BSW north of St. Lawrence Island in August range from -1.6 to -2.1"/fj(i (Fig- 2). The resident cold pool measured in the central Gulf of Anadyr southwest of St. Lawrence Island in August 1988 was composed of less saline water (32.4'V,j„) with a 5 '"Oof -2.0"/oo. Coachman ef a/. (1975) propose that this cold pool results from less saline water off the Alaska coast being advected into the area between St. Matthew and St. Lawrence Islands. It is subsequently cooled and salinated in the winter and then is isolated from surrounding shelf waters in the summer, although some mixing occurs along its boundary with northward flowing water from the southeast Bering Sea Shelf to form the modified Bering Shelf water advected north of St. Lawrence Island in the summer. A significant correlation was found between the stable oxygen isotope composition of bottom seawater and salinity in the study area, enabling determination of 8 "*0 values for the major water masses in the region dependent on freshwater dilution of the most saline Bering Sea basin core water as it moves onto the shelf (Fig. 2). The water most depleted in '"O was found offshore of the Yukon River (Figs. 2,3), with intermediate concentrations found in Bering Shelf water. The Fig. 3. Distribution of bottom waters 6 '"O values for stations occupied during the 1988 RA' Akmlemik Korolev cruise 47 ( • ) and the 1987 R/V Thomas Thompson cruise 214 (o). Isotope ration units: (Grebmeier fro/., 1990). waters most enriched in '"O were found to the west in high salinity Anadyr water. In addition, the 8 '"O-salinily dilution line shows the influence of brine rejection during ice formation enhancing salinity of the southeast-flowing Siberian Coastal water in the Chukchi Sea, even though the 8 "O remained constant in relation to the northwest-flowing Bering Shelf- Anadyr water, indicating the Siberian Coastal water sampled probably originated from south of Bering Strait. 246 The stable oxygen isotope composition of tunicate cellulose and its relationship to the water mass the animal grows in was studied for the first time in a polar system during the 1 988 field season in the major water masses of the northern Bering and Chukchi Seas. The 5 '''O values in the major water masses were mirrored in the 8 '"O values of the cellulose in the benthic tunicates living in/on the underlying sediments (Figs. 3,4 ). Our objective was to test for possible short- and long-term signals for water mass location in this region. By measuring the "*0 content of cellulose in tunicates, which are immobile as adults, we found evidence that these animals provide a long-term indication (over a 1-3-yr. lifespan) of water mass location during the growing season, presumably during the ice-free summer months (Fig. 4). Due to oxygen isotope fractionation during cellulose synthesis, the 8 "'O values of tunicate cellulose Fig. 4. Distribution of tunicate cellulose 8 '"O values for stations occupied during R/V Akademik Korolev cruise 47 (•) and R/V Alpha Helix cruise 1 I3(»)in 1988. Isotope ratio units: '7„|(Grcbmeierf/(7/.. 1990). are positive, but the relative ~2T/,„ enrichment in "O is consistent with differences between each water mass. This signal was also observed in tunicates underlying the Siberian Coastal water. Sediment Oxygen Uptake Rates The high nutrient load of the Anadyr water provides a continuous source of nutrients for high primary production in the water column during the open- water season on the west side of the shelf from the Gulf of Anadyr to north of Bering Strait, but nutrient depletion limits production along the Alaska coastline after the spring bloom (Fig. 5; Walsh et ai, 1989). Fig. 5. Depth-integrated distribution of chlorophyll a ( mg m - ) during August 1988 (after Walsh et ai. 1989). KEY ' 1964-1987 stations 1988 stations values < 10 mmol Op m' d' Fig. 6. Distribution of sediment oxygen uptake rates (mmol O., m • d ') for 1984-1986 {from Grcbmcier & McRoy. 1989) and 1988 (this study). 247 The distribution of sediment oxygen uptake rates measured in the Bering and Chukchi Seas in 1 988 ( Fig. 6) is similar to water column chlorophyll a concentrations ( Fig. 5 ). It further indicates the extension of a high sediment respiration zone, which can be used as an indicator of food supply to the benthos, to the west of the previously known zone in US waters (Grebmeier & McRoy. 1989). The highest benthic respiration rates in the southern Chukchi Sea occurred in the central region where a similar value was measured in 1985 (-35 mmol O, m-d'; Fig. 6). In contrast to the sediment regimes under Alaska Coastal water, sediment uptake rates in Siberian Coastal water and offshore Bering Shelf- Anadyr water had high respiration rates, indicating enhanced food supply to the benthos. Only a limited number of sediment respiration measurements were made in the Gulf of Anadyr, with values ranging from 10 to 40 mmol O, m-d '. Further sampling is necessary to determine realistically organic carbon supply to the various regions of the gulf. Benthic Macrofaiinal Biomass and Community Structure The highest benthic macrofaunal biomass for the study area was recorded in the southern Chukchi Sea in 1 988 and was coincident with the location of highest macrofaunal biomass measured in the previous 1984-86 study period (-30-60 g C m-; Fig. 7). The extension of this high biomass zone to the west, both under Siberian Coastal water and Anadyr-Bering Shelf water, suggests a major depositional regime for high quality organic matter to support the high secondary productivity in the underlying benthos. This western region of the Chukchi Sea contrasts greatly with the nearshore Alaskan waters, where benthic biomass nomially remained below 10 g C m-. Ampeliscid and isaeid amphipods and tellinid and nuculid bivalves dominated the benthic fauna in the offshore region of the southern Chukchi Sea (Fig. 8). Benthic regions closer to the Alaska coastline were characterized by a mixture of communities, including tellinid and nuculid bivalves, echiurids, brittle stars, phoxocephalid, isaeid and ampeliscid amphipods, maldanid and oweniid polychaetes, and styelid tunicates. The variability in benthic community composition indicates the heterogeneity of the sediments underlying the Alaska Coastal water (Grebmeier et ai, 1989). The highest biomass in the northern Bering Sea, north of St. Lawrence Island, was observed in the central basin, with lowest values once again along the Alaskan coast (Fig. 7; Grebmeier «'/«/., 1989). Ampeliscid and isaeid amphipods and tellinid bivalves dominated sandy sediments in this central region. Brittle stars and sea urchins were common in Anadyr Strait. A variety of benthic fauna characterized the region under Alaska Coastal water, which included ampeliscid and isaeid amphipods, tellinid and nuculid bivalves, echinarachniid sand dollars, and echiurids. The Gulf of Anadyr is characterized by two major faunal populations. The inner gulf is composed of a high biomass (10-^0 g C m-) of tellinid and nuculid bivalves and capitellid and scalibregmid polychaetes. These animals are deposit feeders, indicative of the fine-grained sediment structure in Fig. 7. Distribution of macrofaunal benthic biomass (g Cm ') for 1984-1986 (from Grebmeier ('/((/., 1988) and 1988. this region. The outer gulf is composed of a more variable biomass ( 1^0 g C m -) of nuculanid and nuculid bivalves and capitellid and scalibregmid polychaetes. The area of high organic carbon supply to the benthos, indicated by high sediment respiration rates (Fig. 6). supports a rich benthic biomass of amphipods and bivalves (Figs. 7,8), which in turn support the dominant benthic-feeding marine mammals in the region, the California gray whale (Eschrichtius gibbosus) and Pacific walrus ( Odobenus ros marus). Sediment oxygen uptake rates and benthic biomass show a strong pelagic- benthic coupling north of St. Lawrence Island into the southern Chukchi Sea, with the lowest apparent food supply to the benthos occurring in the low biomass regions underlying the Alaska Coastal water (Figs. 6,7). Sediment respiration and benthic biomass data were collected concurrently in the Gulf of Anadyr for the first time in 1988. The results support a high organic carbon flux to the benthos in the shallow nearshore Siberian waters and offshore regions southwest of St. Lawrence Island, with lower values in the central Gulf of Anadyr and deeper slope regions ( Figs. 6,7 ). The increased benthic biomass and sediment respiration on the shelf in the eastern part of the Gulf of Anadyr is in an area affected by the St. Lawrence Island polynya (SLIP) in the winter/spring (Arctic Ocean Sciences Board. 1 989), which indicates the region may be exposed to an additional carbon supply from enhanced open-water polynya primary production in the late winter-early spring. 248 Total Organic Ccuhan ami Nitrogen in Surface Sediments Both the quantity and quahty of organic matter reaching the benthos inlluences bcnthic standing stock and sediment respiration (Grebmeier et al., 1988; Grebmeier & McRoy, 1989). Total organic carbon (TOG) in surface sediments was highest in the Gulf of Anadyr and the western region of the Chukchi Sea ( Fig. 9 ), indicating a higher proportion of silt and clay in these sediments. The lowest TOG occurred in sediments under the Alaska Goastal Water (Fig. 9). The region north of St. Lawrence Island to Bering Strait has relatively low total organic carbon accumulating in the sediments due to the increased current speeds in this region. Fine sands characterize this sediment domain (Grebmeier era/., 1989). In addition, the general shape of the TOG isolines follow the bathy metrically- steered currents (Fig. 1). This is consistent with previous findings that indicate the influence of hydrodynamics on organic carbon loading and sediment composition, which in turn influences benthic population community structure and biomass in this region (Grebmeier et ai, 1988, 1989). High quality organic carbon settles to the benthos in these shallow waters, as evidenced by the low G/N values in sediments under the highly productive Gulf of Anadyr and Bering Shelf- Anadyr waters (Fig. 10). In contrast, highestC/N ratios (lowest quality material) occur in sediments underlying the outer shelf sediments in the Gulf of Anadyr and Alaska Goastal water in both the northern Bering and Chukchi Seas (Fig. 10). A similar pattern was observed between 1 984 and 1 986 to the east of the Fig. 8. Distribution of benthic communities based on data Irom 1984-1986 (from Grebmeier rt a/., 1989) and 1988. Fig. 9. Distribution of total organic carbon Ci) in surface sediments during August 1988. Fig. 10. Distribution of C/N rations (wt./wt.) in surface sediments during August 1988. 249 international date line and the influence of refractory terrestrial material on this food source, coming into the marine systems from Alaskan rivers, is supported by previous work (Grebmeier et al., 1988; Walsh et ai, 1989). Natural Radioisotope (-'"Pb) Content in Surface Sediments A preliminary study of spatial ''"Pb-ex distribution in surface sediments at select stations in the Gulf of Anadyr, northern Bering Sea, and southern Chukchi Sea indicated a higher concentration of the particle-reactive radionuclide -'"Pb in the higher silt and clay content sediments of the Gulf of Anadyr and southern Chukchi Seas (Fig. 11). This limited data set had a high correlation between surface sediment TOC and -'"Pb content (n = 9, r- = 0.7 1 . 0.00 1 < p < 0.005 ), indicating that regions of higher organic carbon content in the sediments were also regions of higher sedimentation and accumulation of organic matter from the overlying water column to the sediments. The highest -'"Pb-ex concentration in the Gulf of Anadyr occurred at the mouth of Kresta Bay, suggesting enhanced deposition of terrigenous and marine material at this site. In the Chukchi Sea. the highest -'"Pb-ex (3.8 dpm/g) occurred in the "hot spot" of high primary and benthic secondary productivity, and the lower total organic carbon in the sediments (1.3%) relative to surrounding stations may result from the high benthic consumption of organic matter at this site. The lowest -'"Pb-ex concentrations were measured in the sandy sediments of the northern Bering Sea (0.6-1.0 dpm/g), along with low organic carbon content (0.3%). However, this area is a region of high water column chlorophyll and benthic biomass. Recent studies by Blackburn ( 1987) suggest that efficient grazing by the benthic amphipods, along with rapid mineralization of organic matter in the sediments, results in lower sediment organic carbon content in this region. The present study, in addition to earlier -'"Pb studies (Grebmeier, unpubl. data), supports a reduced sediment accumulation in this region, although carbon flux to the benthos is high (Grebmeier & McRoy, 1989; M. Fukuchi, personal communication). An additional study was undertaken to determine the sedimentation rates based on vertical cores within each of the main study areas (Fig. 12). Preliminary data, based on natural log-normal distributions of -'"Pb-ex in sediment .sections with depth down the sediment core in the Gulf of Anadyr and southern Chukchi Sea, indicate low but variable sediment accumulation rates. Sedimentation rates ranged from 0.01-0.03 mm/yr in the southern Chukchi Sea to 0.04 mm/yr in the Gulf of Anadyr. The difference between these two regions is evident in the highly variable -'"Pb-ex values in the top 0- 1 0 cm in the southern Chukchi Sea stations ( Stations 45, 55), due to the extremely high mixing of these sediments by the high benthic fauna populations (Fig. 7; Grebmeier, 1987; Grebmeier & McRoy, 1989). In comparison, the one station analyzed in the central Gulf of Anadyr ( Station 22 ) occurred in a low benthic faunal abundance region in the central gulf ( Fig. 7 ), such that the surface sediment was little mixed and the -'"Pb-ex profile was undisturbed. Further studies are needed on longer cores in both the Gulf of Anadyr and Chukchi Sea to evaluate organic carbon sedimentation and accumulation in the Excess Pb-210 (dpm/g) 0 1.0 2.0 3,0 4,0 3. 4 E 73 12 16 47-100 + 47-045 47-055 Fig. 1 1. Distribution of-"'Pb-ex (dpm/g) und total orgunii; carbon (%)al select .stations during August 1988. Fig. 12. Verticle profile of -'"Pb-ex (dpm/g) at select stations in the Gulf of Anadyr: Station 22 ( AK47-022^ ); and southern Chukchi Sea: Station 45 (AK47-045 •) and Station .S.^i (AK47-055 o ). An additional -'"Pb-ex concentration for a surface sample (0-3 cm) in the northern Bering Sea is presented for coinparison: Station 100 (AK47-I00 +). sediments of these arctic regions. Previous data from the sandy sediments of the northern Bering Sea indicate little or no sediment accumulation in this region, with sedimentation rates a magnitude lower than values in the other two regions (Grebmeier, unpubl. data). These data support the conclusion presented earlier — that although organic matter is settling to the benthos in this region, highly efficient benthic faunal 250 consumption, sediment mineralization, and resuspension by benthic-feeding marine mammals inhibit fine sediment and organic carbon accumulation in this region. In conclusion, the shallow continental shelfof the northern Bering and Chukchi Seas exhibits a direct coupling of water column primary production to secondary benthic production and carbon cycling. The deposition of a high quantity and quality of organic carbon to the western regions of this area supports extremely high populations of benthic fauna, which in turn provide a large food source for benthic-feeding marine mammals. Shallow marine shelves in polar regions are important sites for carbon cycling and are likely to be directly impacted by global climate changes. Many thanks to the following people for assistance at sea during the study; D. Adkison, D. Veidt, T. Whitledge, V. Koltun, and B. Sirenko. L. Cooper performed all of the required chemical extractive procedures and vacuum line manipulations, while D. Winter performed the mass spectrometric analyses. Thanks to D. Hammond for suggestions and laboratory support during postdoctoral work at the University of Southern California. C. R.Olsenandl. L. Larsenof the Environmental Sciences Division, Oak Ridge National Laboratory, provided valuable technical advice and additional radionuclide analyses. Financial support was provided by NSF grants DPP 88- 13046, DMB 84-05003, DMB 88-96201. and DOE grant 87-ER606I5. This project was part of the Third Joint US-USSR Bering & Chukchi Seas Expedition aboard the Soviet research vessel Akademik Korolev. I express appreciation to the US Fish and Wildlife Service, USA, and the State Committee lor Hydrometeorology, USSR, who made participation on the project possible. Finally, I thank the captain and crew of the R/V Akademik Korolev for cooperation in the field. 7.2 Characteristics of Benthic Biocenoses of the Chukchi and Bering Seas BORIS I. SIRENKO and VLADIMIR M. KOLTUN Zoological Ii\stilHte. USSR Academy of Sciences, Leningrad. USSR Introduction Benthic fauna of the boreal and southern regions of arctic waters of the World Ocean are characterized by relatively high faunal diversity and biomass. Thus, the benthos plays a very important role in the energy balance of the marine ecosystem. At the same time most benthic organisms are quite sensitive to various environmental effects. In recent years the most prominent effect has been exerted by anthropogenic factors that have been increasing annually. In this respect, global ecological monitoring of the World Ocean is becoming more and more vital (Izrael & Tsyban, 1985). The present article is a continuation of the work started in 1977 by the USSR Committee on Hydrometeorology and Environmental Control in the Bering Sea. In 1988, the group of scientists that studied problems of the benthos during the 47th cruise of the research vessel {RfV) Akademik Korolev put forward the following tasks: J. definition of the structural characteristics of benthic communities in the regions covered by the expedition; 2. analysis of the quantitative distribution of benthic fauna; and 3. determination of annual variations in the structure of benthic ecosystems, if any, and reasons for these variations. It should be noted that the regions studied were selected based on data available from previous investigations. First attempts to quantitatively study characteristics of the benthos in the northern part of the Bering and Chukchi Seas were made in 1 933 during the cruise of the R/V Krasnoanneyets (Deryugin (felvanov, 1937;Makarov, 1937). Then, from 1950-52, more detailed studies of qualitative and quantitative characteristics of the benthos of the northwestern part of the Bering Sea were carried out during the cruise of the RA' Vityaz ( Vinogradova, 1954;Zenkevitch&Filatova, 1956;Belyaev, 1960;Filatova& Barsanova, 1964). Eastern and central parts of the Bering Sea were thoroughly studied during several cruises as part of Soviet expeditions in 1958-1960 (Neiman, 1963) and by American scientists in 1970-1974 (Alton, 1974;Stoker, 1981). In recent years investigations of the Bering and Chukchi Seas benthos were carried out by both Soviet (Sagaidachny & Chistikov, 1987) and American scientists (Grebmeier era/., 1988, 1989; Grebmeier & McRoy, 1989). On the basis of prior research and the present study, we investigated the annual variations of some benthic biocenoses and their quantitative characteristics in the Bering and Chukchi Seas. Material and Methods Samples of benthic fauna collected in 1988 during the 47th cruise oiiheRN Akademik Korolev in the Bering and Chukchi Seas were used as materials for the present study. A total of 1 59 macrobenthic samples from 86 stations were collected during the cruise, including 48 samples collected with a trawl and 1 1 1 samples collected with a dredger. Of the dredger samples, 25 were tested for qualitative parameters, with the remainder analyzed for quantitative parameters. In addition, meiobenthic samples were obtained at 46 stations. Samples were collected in three main regions: the Gulf of Anadyr and neighboring waters (14 trawl samples and 26 dredger samples); the northern Bering Sea from St. Lawrence 251 Island lo Bering Strait (11 trawl samples and 35 dredger samples); and in the southwest Chukchi Sea ( 1 8 trawl samples and 43 dredger samples; Figs. 1,2). In addition, five trawl 180 175 170 ; ^ ^ CHUKCHI / ^ y A PENINSULA ^ -Y_/'^ Gulfo 26 AAA 27 ^ ^ ^ Anadyr A \ -IP - \ A 31 . \ A 30 Z\A MA \ 25 ▲ 24 A A 29 32 A 41 ''aa(s~5$^;^-^ 36 X*' J \ 23 34 1 AA AA \^ k 22 35 / AA 15 AA ^-^ AA 19 13 AA 11 AA 9 AA 18 AAA Benng 5ea 7 65 63 62 61 Fig. K Distribution of quantitative (A) and qualitative (^) samples at stations in 1988 in the Gulf of Anadyr and neighbonng waters in the Bering Sea. 170 Chukchi Sea Bering Sea Fig. 2. Distribution of quantitative (▲) and qualitative (^) samples of benthos at stations in 1988 in the southeastern part of the Chukchi Sea and in the northern part of the Bering Sea. samples and eight dredger samples were collected in sampling grids further south in the Bering Sea, designated as East and South Polygons. The East Polygon was in the central part of the Bering Sea covering both its continental shelf and slope, and the South Polygon was in the southern part of the Bering Sea, near the Aleutian Islands. Samples were collected with the following equipment: Sigsby trawl (small size version: 0.9 m entrapment width, 0.5- mm mesh, 20-min trawl at 3 knots); dredger Ocean (entrapment area 0.25 m-), and van Veen bottom sampler (entrapment area 0. 1 m'). Dredging and trawling were carried out from starboard using a winch on the bow of a ship. Trawling was carried out for 20-min time periods while the ship was adrift. Most of the dredged samples were collected with a van Veen sampler. Usually two dredger samples at one station were averaged and treated as one sample. Meiobenthos samples were taken from the dredger samples. Seabed fauna was washed off on a washer using a set of 1 0. 5 , and 1 mm mesh sieves. After treatment, the extracted organisms were fixed in 4% formalin or 75% ethanol. The collected material was classified and treated in the ship lab. Preliminary identification of organisms was carried out to lowest taxon level possible. Final analysis of benthic material is still under way in the Institute of Zoology (USSR Academy of Sciences). Results The following section presents a brief review of the benthos of each of the investigated regions of the Bering and Chukchi Seas. The Gulf of Anadyr and Neighboring Waters The research work in the studied regions of the Gulf of Anadyr was carried out in the central part of the gulf and on the shelf at the gulf outlet. Due to the limited quantitative material obtained, only 5 biocenoses (Fig. 3) with 28 dominant benthic forms were determined (Table 1 ). Average biomass of benthos in the region equals 461 g m-. The most widespread benthic community is the biocenosis of ark shells Macoma cakarea that inhabit the entire central part of the Gulf of Anadyr at depths of 47-140 m. This biocenosis is subdominated by ark shells (Leionucula inflata, Cyclicardia crebricostata. and Yoldia). polychaetes (Amphictene moorei, Nicomache himbricalis. and Nephtys ciliata), ophiurae (Ophiiira sarsi), and some other bottom organisms. Alongside Macoma, another widespread organism is Leionucula: at some peripheral stations its biomass is equal to that of the dominant biocenosis. At Stations 24. 29, 30. and others that are situated in the center of the biocenosis, Macoma dominates completely; its biomass equals 80-94% of the total biomass of all benthos. Maximum benthic biomass at these stations reaches over 1,000 g m- (Fig. 4). Average biomass of the benthos in the Macoma calcarea biocenosis equals 616 g m -. The biocenosis Nuculana lameUosa radiata occurs in the open sea, south from the Macoma biocenosis. at a depth of 63-88 m within the lowest temperature region in the study area. 252 TABLE 1 Dominant benthic forms of the Gulf of Anadyr ( I ), northern part of the Bering Sea (2) and southeastern part of the Chukchi Sea (3). Questionable determination indicated by (?). Dominant forms 1 T 3 Dominant forms 1 2 3 Sponges Mollusks Halichondha panicea + + - Tridonta borealis - - + Coelenterata Cyclocardia crebricostata + + + Haliactis arctica - - + Liocyma fluctuosa - + - Epiaclis levisi - - + Macoma calcarea + + + Cersenia rubiformis - + - Leionucula inflata + + + Polychaetes Nucukma lamellosa radiata + - + Ampharete acutifrons + + + Serripes groenlandicus - + + Lumbrineris sp. + + + Yoldia amygdalea + + + Nicomache liihricalis + + + Tachrhynchiis erosus + - - Maldane sarsi + + + Echinodemiata Nocamphitrite groenlandica - - + Ctenodiscus crispatus + - - Nephtys pente - + 7 Gorgonocephalus caryi - + + Nephtys caeca + + + Ophiura sarsi + - + Nephtys ciliata + + + Opbiura sp. + + - Cistenides granulata + + - Echinarachnius parma + + - Phyllodoce groenlandica + - + Strongylocentrotiis pallidus + + + Amphictene moorei + - - Strongylocentrotus Scalibregma inflatum - + - droebachiensis - + - Stemaspis scutata - - + Myriotrochus rinkii - - - Siphunculida Holothuroidea - - + Golfingia margaritacea + + + Ascidia Echiurida Boltenia ovifera + + - Echiiinis echiiinis + - + Boltenia echinata - - + Bryozon Pelonaia cornigata - - + Alcyonidiion vennicidare - + - Synoicum solidum + + - Biyozoa sp. + - - Crustacea Total number of dominant forms Balanus crenatiis + + + for each region 28 28 29 Ampelisca sp + + + This is a pronounced biocenosis that was found at three stations (18, 19, and 22). Nucukma dominated the biocenosis, and its biomass constituted 80-90% of the total benthic biomass, which reached 2,81 1 g m-, average benthic biomass of the biocenosis oi Nucukma equaled 1,413 g m -. In the eastern part of the gulf, at a depth less than 50 m Macoma biocenosis is replaced by the biocenosis of sand dollars Echinarachnius parma. Station 25 was a boundary one where both dominant biocenoses are found. In the southeast region of the study, at a depth of 97-140 m, there is a biocenosis that is characterized by domination of polychaetes Nepthys ciliata and Nicomache luhricalis. along with ophiurae. Average benthic biomass of this biocenosis is not large if compared to the previous one and equals only 78 g m -. In the region between the continent and St. Lawrence Island, on mixed sediments of pebbles and rocks, there is a specific biocenosis dominated by sessile benthos (sponges Halichondria panicea, ceripedion Balanus crenatus, ascidiae Ascidiae. and sea hedgehogs Strongylocentrotus pallidus). Northern Bering Sea Due to the complexity of the hydrological regimes in the region north of St. Lawrence Island to Bering Strait, the biocenoses of the benthos are also very complicated. Three different water masses (waters of the Gulf of Anadyr, shelf waters of the Bering Sea, and Alaska Coastal waters) and enormous diversity of sediment grain size composition contribute to a mosaic structure of benthic faunal distribution. Small numbers of quantitative samples collected in this region 253 175 170 Bering Sea 65 62 61 Fig. 3. Distribution of biocenoses in the Gulf of Anadyr and neighboring waters. \-Macoma calcarea: 2-Nuculana lamellosa radiata; 3- Pohchaem: 4-Echinarachnius parma: i-Halicbomiria panicea + Balamis crenalus + Sirongylocenlnnus pallidus. 180 Fig. 4. Distribution of benthic biomass (g m -) at stations in the Gulf of Anadyr and neighboring waters. only allow determination of three biocenoses (Fig. 5). The region is dominated by 28 forms of benthic organisms (Table 1). Similar to the Gulf of Anadyr, there is also Macoma calcarea biocenosis; it was found in two areas in both the north and south areas of this region. The region was subdominated, and sometimes even dominated alongside of Macoma, by other ark shells (Yoldia amygdalae and Leioinicula inflata), polychaetes (Nepthys caeca and Moldane sarsi). amphipods, ceripedions(fia/fl/7/M(:re;;rt/«.v), and sponges. Maximum benthic biomass of this biocenosis (found at Station 89) is smaller than in the previous region and equals 649 g m -. North of St. Lawrence Island, in the eastern part at the banks of the Alaska coast and in the western area near the Soviet coast, we can clearly identify a biocenosis of sand dollars (Echinarachniiis pamia). with average biomass of 2,358 g m - and an extremely high maximum biomass of 4,378 g m- (Fig. 6). The entire region of the Bering Strait proper, from the Chukchi Peninsula to Alaska, as well as a small area to the north of St. Lawrence Island, at a depth of 44-50 m, is characterized by pebble and gravel sediments with stones, sand, and shells. This area is inhabited by fauna that is typical for this part of the Pacific with solid and mixed sediments: sponges Halichondria panicea; alcionariae Gersemia nibifonnis\ hedgehogs Strongyloceutrotus pallidus; ceripedions Balamis crenatus; and ascidiae Didendum sp. Benthic biomass in this biocenosis reaches 780 g m'-. Chukchi Sea Bering Sea m^ 5 Fig. 5. Distribution of biocenoses in the southeastern part of the Chukchi Sea and northern part of the Bering Sea. I -Macoma calcarea: 2-Lewnucula inflata: y Echinarachniiis parma:4-Haltchondriapanicea + Balamis crenalus + Slronnylocentroliis pallidus: 5-Serripes groenlandicus. Southeastern Chukchi Sea Average benthic biomass of the region is 673 g m -. It is dominated by 29 various benthic faunal forms (Table 1). Differences in distribution of benthos in the eastern and western parts of the region had been distinguished earlier by Grebmeier et al. (1988) and were observed during the present expedition. These differences are determined by peculiar features of waters surrounding these regions. A more diverse western part of the region has a most productive biocenosis (Macoma calcarea) at a depth of 38-52 m on muddy and sandy sediments; average biomass of this biocenosis is rather high and equals 979 g m - 254 with maximal biomass equal to or greater than 2,000 g m- (Stations55, 69; Figs. 5,6). At most ofthe stations (48, 55, 57, 60, and others), Macoma biomass by far exceeds that of other organisms of the biocenosis, equaling 60-70% of the total biomass. Alongside Macoma, this biocenosis is also dominated by ark shells (Leionucula inflala and Yoldia amygdala), polychaetes (Nepthys caeca. Maldane sarsi, Nicomache lumbricalis, and Lumhrinaris sp.), ophiurae (Ophiuni sarsi), and amphipods (Ampelisca spp.). 170 165 Chukchi Sea (1068)'°° Bering Sea Fig. 6. Distribution oi bcnthic biomass (g m -) at stations in the northeastern part of the Chukchi Sea and the northern part of the Bering Sea (symbols as in Fig. 4). In the western part ofthe region, the Macoma biocenosis borders the Leionucula inflata biocenosis at a depth of 44-50 m. Leionucula is obviously dominant here, as its biomass is 60-80% ofthe total biomass of biocenosis organisms. Average benthic biomass in the Leionucula biocenosis is 647 g m -. Closer to the Soviet coastline, there is a diverse biocenosis of ark shells {Mya truncata). The only bottom sample at Station 44 (entrapment area, 0.1 m') only penetrated to a shallow depth and cut off eight siphons of the large, deep- dwelling moUusks. South from the Macoma biocenosis, closer to Bering Strait, there is a pronounced mosaic character of benthic organisms. Different bottom samples show domination by various groups, including ascidiae, polychaetes, ark shells, holothuria, and sipunculida. In the eastern part ofthe region, near the Alaska coastline, at depths of 22-35 m, only an insufficient level of biocenosis of Senipes groenkmdicus ark shells occurs, with an average biomass of 228 g m -. The degree of domination by this species is minimal in this biocenosis. Other stations were marked by domination of polychaetes (Lumhrineris, Neoamphitrite, Maldane. Nephtys. Cistenides, and Niomache), ark shells (Leionucula, Nuculana, and Cyclocardia), numerous small holothuriae {Myriotrochus), actiniae (Haliactis and Epiaciis), and echiurids. Sessile benthic fauna was collected at Station 52 in 50 m of water; the dominant species was Balanus crenatus, which had a very high biomass (about 970 g m -; Fig. 6). In general, we should note a striking difference between abundance of benthos between the western and eastern parts of this region. In the west, there is an influence ofthe Gulf of Anadyr, Bering Sea Shelf waters, and waters of the Siberian shallows; in this region, average benthic biomass equals 673 g m '. In the east, there is an influence of depleted coastal waters of Alaska; average benthic biomass equals only 315 g m- (even with a relatively rich sample with Balanus), which is over two times less than in the western part. Benthos at East and South Polygons At East and South Polygons, 13 samples were taken at depths between 140 and 3,700 m; 8 of these samples were collected with a bottom sampler. Most of the samples are dominated by polychaetes ( usually from the family Maldanidae); in abysses at 3,000 m, there is a domination by large monocelled organisms (Komokiacea). Biomass at all stations is not large and varies from 0.7 g m - (in abyss) to 14.4 g m"' (in sublittoral regions); average biomass equals 7.5 g m -. Discussion Biogeographic Characteristics of Benthic Fauna ofthe Northern Bering and Chukchi Seas In terms of biogeography. the investigated regions ofthe Gulf of Anadyr, northern Bering Sea, and southeastern Chukchi Sea have very few differences. There is an advantage for a few species to dominate the faunal distributions in the region; 1 4 of 45 species that are dominant within each of these three regions are common for all of the regions (Table I). Twelve of the species can be found in two of the three regions. Only 19 species dominate in only one region. In all three regions, most of the area is occupied by Macoma calcarea biocenosis. The similarity of faunal characteristics between all three regions can be explained by the fact that they are all situated in the arctic area to the north of the Andriyashev Anadyr faunistic barrier (Andriyashev, 1939); this fact determines the similarity of most ofthe fauna. One can also note certain peculiarities within each ofthe regions. In this respect, the most demonstrative one is the southeastern area of the Chukchi Sea. The western part of this region is dominated by boreal-arctic species of the panarctic complex (Macoma calcarea. Leionucula inflata. Yoldia amygdala. Haliactis arctica, and Epiactis levisi); a narrower and relatively warmer eastern part is dominated by 255 warm water boreal-arctic species (Serripes gwenlandicus. Ampharete acutifrons, and Golfingia margariacea ) with limited occurrence in the Arctic. Preclassification of the collected benthic material indicates that some species that were found during the expedition had never been known to inhabit the Chukchi Sea before (e.g., coat- of-mail shells Hanleyella asiatica, some obelis shells, and some species of echinodermata). Annual Variation in the Distribution of Benthic Organisms Although the number of samples collected is not large, it allows us to compare the distribution of benthic organisms with that of previous expeditions (Deriugin & Ivanov, 1937; Makarov, 1937; Vinogradova. 1954; Neiman, 1963; Stoker, 1981; Grebmeier et ai. 1989). First of all, one can note that there is a coincidence in the location of principal biocenoses (i.e., Macoma calcarea, Echinarachnius parma. and sessile species biocenoses in the straits). According to data from the first quantitative benthos analyses in 1 933, in the central part of the Gulf of Anadyr, there was a domination of Macoma ca/carea (Makarov, 1937). Analysis of materials collected by the Institute of Oceanology, USSR Academy of Sciences, on the RA' Vityaz (1950-1952) provides a general confirmation for these data (Vinogradova, 1954; Filatove & Barsanova, 1 964 ). We should also note that, in some works, an overemphasis was given to Ophiura «7r.s/ (Vinogradova, 1 954; Zenkevitch & Filatova. 1958), which entitled the biocenosis even though it has a much lower biomass than that of ark shells (Vinogradova, 1 954). Obviously, it can be explained on the one hand by undue attention being paid to the number of individuals collected in a trawl ( a Sigsby trawl usually collects echinodermata, including ephiurae that inhabit the surface of the sediments), and on the other hand by density indices (Brotskaya& Zenkevitch, 1939) used for definition of communities and groups instead of the later accepted method of biocenosis definition based on biomass (Petersen, 1911, 1913; Vorobyov, 1949). A number of works based on the same material from the Gulf of Anadyr (Vinogradov, 1954; Zenkevitch & Filatova, 1958; Filatova & Barsanova, 1 964) locate biocenosis and groups with domination of either Ophiura sarsi or Macoma calcarea in different regions. It is interesting to note that the biomass characteristic of Ophiura sarsi found in trawl catches in 1933 and 1950-52 in the central part of the Gulf of Anadyr was not confirmed by the material that we collected in 1988. Ophiura sarsi was traced only in 3 dredger samples out of 26; it constitutes from 2 to 10% of the total biomass of the sample. Only 3 out of 14 trawl samples collected in the Gulf of Anadyr at a mass scale contained Ophiura sarsi. One can assume that there was a decrease of habitation density of these ophiurae during the recent 30-50 years, although to confirm this conclusion a more detailed investigation is required. Alongside the above-mentioned biocenoses that had inhabited the same region for many decades, new biocenoses were found both in the regions that had never been investigated before in the Chukchi Sea (e.g., Leionucula injlata biocenosis) and in the well researched regions in the Gulf of Anadyr (e.g., Nucukma lamellosa radiata biocenosis). The latter example requires a detailed study since it is of special importance for us as a vivid example of how one biocenosis is replaced by another. According to some authors, 28-38 years ago other biocenoses were found on the site where today we ^mdNuculana lamellosa radiata (Figs. 7A,B,C). For example, according to the data collected by the RA' Vityaz in 1950-52 (Vinogradova, 1954; Filatova & Barsanova, 1958), Ophiura sarsi + Macoma calcarea biocenosis was found (Fig. 7 A). According to a 1958-60 expedition, Neiman ( 1963) found there was a Yoldia traciaeformis biocenosis wedged in between Ophiura sarsi and Macoma calcarea biocenoses (Fig. 78). In addition, Neiman (1963) found that the present site of the Nuculana lamellosa radiata biocenosis was partially inhabited by the three above-mentioned biocenoses in 1 958-60, while according to the same data, biocenosis N. lamellosa radiata (probably defined as N. pernula) was located in the form of two small spots much farther to the south. The high degree of domination of Nuculana in our samples (80-90% of the total biomass) and high abundance values (up to 1 ,040-3,700 individuals m -) and a low density oi Macoma (up to 10 individuals m-) leave no doubt that N. lamellosa radiata biocenosis was defined correctly. The earlier data mentioned above, as well as numerous old shells of Macoma in our samples, testify to the fact that earlier this region was inhabited by Macoma calcarea biocenosis. It is interesting to note that according to Makarov ( 1937), in 1933, the region south of St. Lawrence Island was approximately the same region where, in 1958-1960, Neiman ( 1 963 ) found Nuculana biocenosis with five stations dominated by small Leda pemula (Nuculana lamellosa radiata). while at the neighboring Station 6 (where there was a domination of Macoma calcarea), the benthic community was dominated by drilled shells of Leda pernula. One can assume that at least from the 1930"s to the 1960"s, Nuculana biocenosis remained in the same region and then started to expand, and by the late 1 970" s/early 1 980's (i.e., during the last decade), it reached the region that we defined in 1988 where it replaced Macoma calcarea biocenosis. This conclusion is supported by our data where the age of Nuculana lamellosa radiata in our samples does not exceed 7-8 years. The fact that the replacement of Macoma by Nuculana occurred during the last decade is confirmed by an extremely small number of empty Nuculana shells that did not have enough time to pile up during the period equal to the average lifetime of these moUusks. Most likely, the northern boundary of Nuculana biocenosis that borders with the Macoma biocenosis was moving to the northwest; every year Nuculana biocenosis advanced into new areas, thus replacing Macoma biocenosis (Fig. 7D). Data from the 47th cruise of the RA' Akademik Korolev in 1984 indicated that the northern border of Nuculana biocenosis had moved northwards when compared to data collected in 1958-60 (Neiman, 1983; Fig. 7C). In the Gulf of Anadyr, we observed the disappearance of Cyclocardia crebricostata as described earlier by Neiman ( 1 963 ). At present, this earlier biocenosis has been replaced by biocenoses of Manocae and polychaetes (Figs. 3,7). 256 1950-1952 Benng Sea 1958-1960 "^ ^N.^ CHUKCM r 1 ) PENINSULA 3 c \ '\ ^"'\ ^ 1984 Benng Sea ■"''^^ CHUKCHI ^ D r. 1984 1988 ^^^^^X^ 1958-60 Benng Sea ^-3 -4 Fig. 7. Long-slanding variations of distribution of Mfcu/ana/ame/tosararfiato. Maconui cakarea et al., biocenoses in the Gulf of Anadyr and neighboring waters of the Bering Sea. Biocenoses distribution in various years: A-1950-1952 (Vinogradova, 1954); B-1958-1960 (Neiman, 1963); C-1984 (report on the 47th cruise of the R/\ Akademik Korolev); dashed line-present habitation of Nucuhma lamellosa radiala in 1988; D-gradual displacement of the northern boundary o( NucuUma lamellosa radiata biocenosis for 30 years in the northwestern direction (indicated with arrow); \-Macoma cakarea; 2-Nuculana lamellosa radiata. i-Ophiura sarsi; 4-Yoldia traciaefonnis. In the eastern part of the Chukchi Sea (Stations 54, 63, and 64), which is presently dominated by various species of polychaetes, echiurids, and amphipoda, a great number of empty shells of Macoma were found, which testifies to a former biocenosis that might have been dominated by these mollusks. There is also a tremendous increase in the average biomass of Macoma biocenosis in the Gulf of Anadyr that during the last 38 years has increased from 455 g m ' (Vinogradova. 1954) to 612 g m - (our data). Our values of average biomass in the regions studied are 2-2.5 times higher than that recorded 50 years ago (Makarov, 1937). It is hard to provide an unambiguous answer to the problem of variations within the same biocenosis and replacement of biocenoses. Most probably, there is a whole group of biotic and abiotic factors influencing changes in faunal populations and biomass. Let us consider the replacement of Macoma biocenosis with Nuculana biocenosis. It is quite obvious from the data presented by Makarov (1937) that most of the samples dominated by Leda {Nuculana) were collected in the coldest regions (below 0°C), both in the Chukchi and Bering Seas. At the same time, most often Macoma dominates in regions where bottom water temperature is above 0°C (though not in every case). Taking into account the direction of expansion of Nuculana biocenosis (which is a more coldwater species than Macoma). one could draw a conclusion that the cold spot expanded northward to the Gulf of Anadyr. In addition. according to Deryugin and Ivanov ( 1 937), the center of the cold Anadyr spot in 1933 was located in the region of the present location of the Nuculana biocenosis. Another possibility for a change in faunal composition could be preference by the dominant fauna for certain sediment grain size or chemical composition. Nuculana prefers a muddier sediment regime than Macoma (Scarlatto, 1981); it was also noted that the sediment dominated by Nuculana smells of hydrogen sulphide (i.e., there is a shortage of oxygen for mollusks). Nuculaces, which includes Nuculana, Tellinacea. and Macoma. incorporates species that are pocket detritus feeders. Still, \f Macoma can use gills to change its feeding mode to sestonophagy, nuculanae are most likely to feed on particles of food from the seabed by collecting them using labial palpus. Their gills perform only the function of respiration (Kuznetsov, 1984). Itispossiblethatmonofunctionality of the gills of Nuculana under conditions of oxygen deficiency gives them an advantage over Macoma. It is also possible that Nuculanae, like similar deepwater species, use the energy released from vital functions of sulfur bacteria; it may also give them the advantage over Macoma in case of inhabiting sludge contaminated with hydrogen sulphide. Continuing our examination of biocenoses replacement, we would like to discuss the general mechanisms of biocenosis biomass variation both in the case when dominant species are preserved and in the case when they are replaced with other species. During the last 20 years, due to long-standing observations of benthic biocenoses in various water areas, we have accumulated a lot of facts testifying to time variation of benthic biomass (Antipova, 1973, 1975; Antipovaefa/., 1974; Rachor&Gerlach, 1975;Klimova, 1977;Golikove?a/., 1986). Masse ( 1972) was the first person to distinguish three types of time variation of benthic organism's biomass. We will discuss the distribution of various types of dominant species' replacement in relatively stable ( nonseasonal ) biocenoses based on two types: reversible and irreversible. Irreversible replacement occurs either in cases of developing siltation by sediments (e.g., in the Gulf of Possiet; Kobyakov, 1962; Golikov era/., 1986) or in cases of pollution (the Baltic Sea). Reversible types of replacement of dominant species with a long life cycle can occur with considerable variation of abiotic conditions in the environment (considerable change of temperature, salinity, etc. ) that in most cases leads to a complete destruction of biocenosis. When normal environmental conditions are restored, the consequent succession in the long run will restore the previous biocenosis. Some of the shallow water biocenoses of the south Far East undergo similar changes; these biocenoses are characterized by a complete elimination of dominant species due to drastic desalination of water that occurs every 2-3 years. Additionally, reversible types of change of the dominant species may occur due to the change of biotic conditions — for instance, due to an invasion of a large number of predators that almost completely devour the dominant species. One or several subdominant species that are not affected by predators then become dominant; after predators leave the region, the 257 succession leads to restoration of the number and role of the dominant species. This type of change is characteristic of Riiditapes philippiuanon biocenosis in the Gulf of Possiet that is periodically subjected to an invasion of enormous numbers of the sea star Asterias amureiisis that devour practically all adult individuals of those mollusks in the biocenosis. Finally, the reversible type of replacement of dominant species with a long life cycle may occur due to shortage or a complete lack of a usual replenishment with young individuals of the population. In this case, non-occurrence of generations for several years may lead (at a natural limitation of older individuals) to a drastic decrease of biomass of the dominant species — in this case, former subdominant species with long life cycles become dominant. In addition, several species with short life cycles that manage to achieve a rapid and sufficient increase of their biomass due to absence of competition may also become dominant and increase their role in the biocenosis. Later on, with aging of young individuals of the former dominant species of the biocenosis, it can regain its domination. In this case, its domination goes on until the new unfavorable period begins. This situation may be jeopardized if there is more than one dominant species. Which of the various mentioned types of change in dominant species is characteristic of the Gulf of Anadyr is unknown. Only with continued studies of this biocenosis, on annual and interannual time scales, will we be able to determine the causes for the changes in benthic composition in this arctic system. The authors would like to thank J. Grebmeier and D. Adkison for their kind and interested assistance in collecting benthic samples in the wilderness of the Arctic. We would also like to thank G. N. Bouzhinskaya, S. D. Crebelny. A. G. Bazhin. and V. V. Tomanov for a prompt analysis of material. 258 Chapter 7 References Alton, M. S. ( 1 974). Bering Sea benthos as a food resource for demersal fish population. In Oceanography of the Bering Sea ( D. W. Hood, & E. J. Kelly, eds. ), pp. 257-277. Institute Marine Science, University of Alaska, Fairbanks. Andrijashev, A. P. ( 1 939). Essay on Zoogeography and Origin of Fish Fauna of the Bering Sea and Adjacent Waters. Leningrad State University, 185 pp. (in Russian) Antipova, T. V. ( 1973). Distribution and quantity of benthos on the southeastern Barents Sea in 1970. Proc. Polar Inst. Mar. Fish. Oceanogr. 33, 24-33. (in Russian) Antipova, T. V. (1974). Some changes of benthos of the Barents Sea in connection with terminal conditions. Proc. Polar Inst. Mar. Fish. Oceanogr. 21, 91-92. (in Russian) Antipova, T. V., Degtijreva, A. A. & Timochina, A. F. (1974). Changes of several years of biomass of plankton and benthos in Barents Sea. Proc. Polar Inst. Mar. Fish. Oceanogr. 21, 81-87. (in Russian) Arctic Ocean Sciences Board (1989). International Arctic Polynya Program (IAP2). A program of the Arctic Ocean Sciences Board. Institute Marine Science, University of Alaska, Fairbanks. Bedard,P.,Hillaire-Marcel.C.&Page,P.(1981). "*0 modeling of freshwater inputs in Baffin Bay and Canadian Arctic coastal waters. Nature 293, 287-289. Belijev, G. M. (1960). Quantitative distribution of bottom fauna in the northwestern Bering Sea. Proc. Oceanol. Inst. USSR. Acad. Sci. 34, 85-103. (in Russian) Blackburn,!. H.( 1987). Microbial food webs in sediments. In Microbes in the Sea (M. A. Sleigh, ed.), pp. 39-58. Ellis Horwood, Chichester. Brotskaya, V. A. & Zenkevitch, L. A. (1939). Quantitative evaluation of the bottom fauna of Barents Sea. Trans. Inst. Mar. Fish. Oceanogr. USSR 57, 5-126. (in Russian) Coachman, L. K., Aagaard, K. & Tripp, R. B. (1975). Bering Strait: The Regional Physical Oceanography. University of Washington Press, Seattle. Cooney, R. T. & Coyle, K. O. ( 1982). Trophic implications of cross-shelf copepod distributions in the southeastern Bering Sea. Mar. Biol. 70, 187-196. Coyle, K. O. & Cooney, R. T. (1988). Estimating carbon fiux to pelagic grazers in the ice-edge zone of the eastern Bering Sea. Mar. Biol. 98, 299-306. Cutshall. N. H., Larsen, I. L. & Olsen. C. R. (1983). Direct analysis of -'"Pb in sediment samples: Self-absorption corrections. Nuclear Instruments and Methods 206, 309-312. Davies, J. M. ( 1975). Energy flow through the benthos of a Scottish Sea loch. Mar. Biol. 31. 353-362. Davies, J. M. & Payne, P. ( 1984). Supply of organic matter to the sediment in the northern North Sea during a spring phytoplankton bloom. Mar. Biol. 78, 315-324. DeNiro, M.J. & Epstein, S. (1979). Relationship between the oxygen isotope ratios of terrestrial plant cellulose, carbon dioxide and water. Science 204, 5 1-53. DeNiro, M. J. & Epstein, S. (1981). Isotopic composition of cellulose from aquatic organisms. Geochim. Cosmochiin. Acta'XS, 1885-1894. Derjugin, K. M. & Ivanov, A. V. (1937). Preliminary observation on the study of benthos of the Bering and Chukchi Seas. E.xplorat. Fauna Seas 25, 246-249. (in Russian) Deuser, W. G., Ross, E. H. & Anderson, R. F. ( 1 98 1 ). Sea.sonality in the supply of sediment to the deep Sargasso Sea and implications for the rapid transfer of matter to the deep ocean. Deep-Sea Res. 28A(5), 495-505. Eppley, R. W. & Peterson, B. J. (1979). Particulate organic matter fiux and planktonic new production in the deep ocean. Nature 282, 677-680. Epstein, S. & Mayeda, T. (1953). Variations of O"* content of waters from natural sources. Geochim. Cosmochim. Acta 4, 213-224. Epstein, S., Thompson, P. & Yapp, C. J. (1977). Oxygen and hydrogen isotopic ratios in plant cellulose. Science 198, 1209-1215. Feder, H. M. & Jewett, S. C. ( 1981 ). Epifaunal invertebrates of the continental shelf of the eastern Bering Sea and Chukchi Seas. In The Eastern Bering Sea Shelf: Oceanography and Resources. Vol. II (D. W. Hood & J. A. Calder, eds.), pp. 1131-1154. University of Washington Press, Seattle. Feder, H. M., Day, R. H., Jewett, S. C, McCumby, K., McGee. S. & Schonberg, S. V. (1985). Infauna of the northeastern Bering and southeastern Chukchi Sea. In Outer Continental Shelf Environmental Assessment Program. Final Reports of Principal Investigators 32, 1-120. US Department of Commerce, NOAA, Washington, D.C. Feder, H. M., Haflinger, K., Hoberg, M. & McDonald, J. (1980). The infaunal invertebrates of the southeastern Bering Sea. Inst. Mar Sci. Rep. R78-6, University of Alaska, Fairbanks. Feder, H. M., Mueller, G. J., Dick, M. & Hawkins, D. (1973). Preliminary benthos survey. In Environmental Studies of Port ValdeziD. W. Hood, W. E. Shields & E. J. Kelley, eds.), pp. 1-493. Inst. Mar. Sci., Occas. Publ. 3, University of Alaska, Fairbanks. Ferronsky, V. 1. & Polyakov, V. A. (1982). Environmental Isotopes in the Hydrosphere. Wiley Publishers, New York. Filatova, Z. A. & Barsanova, N. G. ( 1 964). Bottom community in the western Bering Sea. Proc. Oceanol. Inst. USSR Acad. Sci. 69, 6-97. (in Russian) Golikov, A. N., Scariato, O. A., Bushinskaya, G. N.. Vasilenko, S. v., Golikov, A. A., Peristenko. L. P. & Sirenko, B. I. (1986). Changes of benthos of Possjet Bay (Sea of Japan) for 259 latest 20 years as a result of accumulation of organic material in bottom deposits. Oceanology 26(1), 131-135 (in Russian). Graf, G.. Bengtsson, W., Diesner, U., Schulz, R. & Theede, H. (1982). Benthic response to sedimentation of a spring phytoplankton bloom: Process and budget. Mar. Biol. 67. 201-208. Grebmeier, J. M. (1987). The ecology of benthic carbon cycling in the northern Bering and Chukchi Seas. Ph. D. dissertation. University of Alaska, Fairbanks. Grebmeier, J. M., Cooper. L. W. & DeNiro, M. J. ( 1990). Oxygen isotope composition of bottom seawater and tunicate cellulose used as indicators of water masses in the northern Bering and Chukchi Seas. Limnol. Oceanogr. 35, 1178-1191. Grebmeier, J. M., Feder, H. M. & McRoy, C. P. (1989). Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. 11. Benthic community structure. Mar. Ecol. Prog. Ser. 51. 253-268. Grebmeier, J. M. & McRoy, C. P. (1989). Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. 111. Benthic food supply and carbon cycling. Mar. Ecol. Prog. Ser. 53, 79-81. Grebmeier, J. M., McRoy, C. P. & Feder, H. M. (1988). Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. 1. Food supply source and benthic biomass. Mar. Ecol. Prog. Ser. 48, 57-64. Hargrave, B. T. ( 1973). Coupling carbon flow through some pelagic and benthic communities. / Fish. Res. Board Can. 30, 1317-1326. Izrael. J. A. & Tsyban, A. V. ( 1 985 ). Ecology and problems of complex global monitoring of the World Ocean. In Complex Global Monitoring of the World Ocean ( Yu. A. Izrael, ed.) pp. 19-48. Leningrad, (in Russian) Jorgensen, B. B. (1983). Processes at the sediment-water interface. In The Major Biogeochemical Cycles and their Interactions (B. Bolin & R. Cook, eds.), pp. 477-509. SCOPE 21, Wiley, New York. Klimova, V. L. (1977). Regularity of distribution and annual changes of bottom fauna in Peter the Great Bay (Sea of Japan). First Meeting of Soviet Oceanologists 2, 40, Moscow, (in Russian) Kobjakova, Z. I. (1962), On some changes of the fauna of coastal parts of Peter the Great Bay of the Sea of Japan. Herald Leningrad State University. Biol. Ser. 24(4), 61-63. (in Russian) Krishnaswami, S., Benninger. L. K., Alier, R. C. & von Damm, K. L. (1980). Atmospherically-derived radionuclides as tracers of sediment mixing and accumulation in near-shore marine and lake sediments: Evidence from ^Be, -'"Pb, and -■ "^ --"'Pu. Earth Planet. Sci. Lett. 47, 307-318. Kuznetzov, A. P. (1984). On role of bivalves in composition of marine bottom populations, their food adaptations and Irophical structure. Proc. Oceanol. Inst. USSR Acad. Sci. 119,47-59. (in Russian^ Makarov, V. V. (1934). Data on quantitative evaluation of benthos in the northern Bering Sea and southern Chukchi Sea. E.xplor. Fauna Seas 25, 260-291. (in Russian) Mass, H. ( 1972). Quantitative investigations of sand bottom macrofauna along the Mediterranean northwest coast. Mar. Biol. 15, 209-220. Mills, E. L. (1975). Benthic organisms and the structure of marine ecosystems. J. Fish. Res. Board Can. 32, 657-1663. Neiman, A. A. (1963). Quantitative distribution of benthos on the shelf and upper slope in the eastern Bering Sea. Trans. Inst. Mar. Fish. Oceanogr. USSR 4S, 145-205. (in Russian) Newrkla, P. ( 1983). Methods for measuring benthic community respiration rates. In Polarographic Oxygen Sensors (E. Gnaiger & H. Forstner, eds.), pp. 274-284. Springer- Verlag, Berlin. Olsen, C. R., Larsen, I. L., Lowry, P. D., McLean, R. 1. & Domotor, S. L. (1989). Radionuclide distributions and sorption behavior in the Susquehanna-Chesapeake Bay system. Maryland power plant and environmental review. PPER-R-12. Annapolis, Maryland. Pamatmat, M. M. ( 197 1 ). Oxygen consumption by the seabed. IV. Shipboard and laboratory experiments. Limnol. Oceanogr. 16, 536-550. Parsons, T. R. K.. Takahashi. M. & Hargrave, B. T. ( 1977). Biological Oceanographic Processes. 2nd Ed. Pergamon Press, Oxford. Patching, J. W. & Rame, R. C. T. (1983). Benthic metabolism and the supply of organic material to the sea-bed. In Experimental Biology at Sea (A. G. MacDonald & 1. G. Priede, eds.), pp. 311-345. Academic Press, New York. Petersen, C.G.J. ( 1911). Some experiments on the possibility of combatting the harmful animals of the fisheries especially the whelks in the Limfiord. Rep. Dan.. Biol. St. 19, 1-20. Petersen. C.G.J. (1913). Valuation of the sea. II. The animal communities of the sea bottom and their importance for marine zoogeography. Rep. Dan. Biol. St. 21, 1—44. Petersen, G. H. & Curtis. M. A. ( 1980). Differences in energy flow through major components of subarctic, temperate and tropical marine shelf ecosystems. Dana 1, 53-64. Rachor, E. & Geriach, S. A. (1955). Variations in macro- benthos. In German Bight Symposium on the Changes in the North Sea Fish Stocks and their Causes. ICES, pp. 11-16. Redfield, A. C. & Friedman, I. ( 1969). The effect of meteoric water, melt water and brine on the composition of Polar Sea water and ofthe deep waters of the ocean. Deep-Sea Res. 16, 197-214. Sagaidachny, A. V. & Chistikov, S. D. ( 1987). Some data on zoobenthos in Bering Sea. In Detailed Analysis ofEcosystems ofthe Bering Sea (Yu. A. Izrael & A. V. Tsyban, eds.), pp. 193-217, Moscow, Scarlato, O. A. ( 1 98 1 ). Bivalves of temperate latitudes in the western Pacific, Nauka Publishers, Leningrad. 408 pp. (in Russian) 260 Schumacher, J. D., Aagaard, K., Pease, C. H. & Tripp, R, B. (1983). Effects of a shelf poiynya on flow and water properties in the northern Bering Sea. J. Geophys. Res. 88, 2723-2732. Smetacek, V. (1984). The supply of food to the benthos. In Flows of Energy and Materials in Marine Ecosystems: Theory and Practice (M. J. Fasham, ed.). pp. 517-547. Plenum Press, New York. Smith, K. L., Laver, M. B. & Brown, N. O. (1983). Sediment community oxygen consumption and nutiient exchange in the central and eastern North Pacific. Linmol. Oceanogr. 28, 882-898. Sternberg. L. & DeNiro, M. J. D. (1983). Biogeochemical implications of the isotopic equilibrium fractionation factor between the oxygen atoms of acetone and water. Geochim. Cosmochim. Acta 47, 2271-2274. Stoker, S. W. (1978). Benthic invertebrate macrofauna of the eastern continental shelf of the Bering/Chukchi Seas. Ph. D. dissertation. Institute of Marine Science, University of Alaska, Fairbanks. Tan, F. C. & Strain, P. M. ( 1980). The distribution of sea-ice melt- water in the eastern Canadian Arctic. J. Geophys. Res. 85. 1925-1932. Valiela, I. (1984). Marine Ecological Processes. Springer- Verlag, Berlin. Vetshteyn, V. Y., Malyuk, G. A. & Rusanov, V. P. (1974). Oxygen- 1 8 distribution in the central Arctic Basin. Oceanol. 14,514-519. Vinogradov, A. K. & Neiman, A. A. (1965). Zoogeographical complexes, trophic zones and marine bottom biocenoses. Transact. Inst. Mar. Oceanogr. USSR 57, 425-426. (in Russian) Vinogradov, M.E. (1954). Materialsonquantitativeevaluation of bottom fauna of some bays of the Okhostsk and Bering Seas. Proc. Oceanol. Inst. USSR Acad. Sci. 9, 136-158 (in Russian) Vorobjev, V. P. (1949). Benthos of Azov Sea. Proc. Azov-Black Sea. Res. Inst. Mar. Fish. Oceanogr., 193 pp. Walsh, J. J. (1988). On the Nature of Continental Shelves. Academic Press, New York. Walsh J. J. & McRoy, C. P. (1986). Ecosystem analysis in the southeastern Bering Sea. Cont. Shelf Res. 5, 259-288. Walsh, J. J., McRoy, C. P., Coachman, L. K., Goering. J. J., Nihoul, J. C. J., Whitledge, T. E., Blackburn, T. H., Parker, P. L., Wirick, C. D., Shuert, P. G.. Grebmeier. J. M.. Springer. A. M., Tripp, R. D., Hansell, D., Djenidi, S., Deleersnijder, E., Henriksen, K., Lund, B. A., Andersen. P.. MuUer-Karger, F. E. & Dean, K. (1989.) Carbon and nitrogen cycling within the Bering/Chukchi Seas: Source regions for organic matter effecting AOU demands of the Arctic Ocean. Prog. Oceanogr. 22, 279-361. Walsh, J. J., Premuzic, E. T. & Whitledge, T. E. (1981). Fate of nutrient enrichment on continental shelves as indicated by the C/N content of bottom sediments. In Ecohydrodynamics (J. C.J. Nihoul, ed.), pp. 13-49. Elsevier Scientific Publishing Company, New York. Wassman, P. ( 1 984). Sedimentation and benthic mineralization of organic detritus in a Norwegian fjord. Mar. Biol. 83, 83-94. White, M. G. (1977). Ecological adaptions by Antarctic poikilotherms to the polar marine environment. In Adaptions within Antarctic Ecosystems (G. A. Llano, ed.), pp. 197-208. Gulf Publishing Company, Houston. Wise, L. E. (1944). Wood Chemi.stn-. Reinhold, New York. Zenkevitch, L. A. & Filatova, Z. A. (1958). General characteristics of qualitative composition and quantitative distribution of bottom fauna of Far Eastern Seas and the northwestern Pacific. Proc. Oceanol. Inst. USSR Acad. Sci. 27, 154-160. (in Russian) 261 Chapter 8: BIOGEOCHEMICAL CYCLES Editors: SERGEI M. CHERNYAK & CLIFFORD P. RICE Subchapter 8.1: Fate of Chlorinated Hydrocarbons 8.1.1 Long-range Transport of Atmospheric Organochlorine Pollutants and Air-Sea Exchange of Hexachlorocyclohexane DANIEL A. HINCKLEY' , TERRY F. BIDLEMAN* , and CLIFFORD P. RICE* ^EA Engineering, Science and Technology, Sparks. Maryland, USA ^Department of Chemistry. University of South Carolina. Columbia. South Carolina. USA *US Fish and Wildlife Senice. Patuxent Wildlife Research Center. Laurel. Maiyland, USA Introduction Recent evidence implicates long-range atmospheric transport and deposition of organochlorine contaminants (OC) to Arctic ecosystems ( Hargrave et al. ,1988; Pacyna & Oehme, 1988: Gregor & Gummer, 1989; Patton et al.. 1989). As a result, these contaminants have been found in arctic fish, marine mammals, birds, and plankton (Andersson £'/<;/., 1988; Kawano et al.. 1988; Muir et al., 1988. 1990a,b; Norstrom etal.. 1988). This raises concern because there are few species in the polar food chain, and arctic animals are able to bioconcentrate many of these hydrophobic pollutants due to their high lipid content. Muir et al. (1990a,b) found that atmospheric deposition of OC and subsequent bioconcentration may lead to high concentrations of pollutants in the diet of native Inuit. The Third Joint US-USSR Bering & Chukchi Seas Expedition took place on the RA' Akademik Korolev (Cruise AK-47). The Soviet Union and United States share a border between territorial waters in this region and, as a result, most scientific studies have been on either the Soviet or American side. The ecology and air masses of the area, however, do not recognize this boundary and a comprehensive investigation is not possible under these constraints. Because this study was cosponsored by the US Department of the Interior and the USSR Academy of Sciences we were able to cross the dateline many times, providing the first complete survey of the area. This paper will address levels of organochlorine compounds found in the atmosphere, microlayer, and surface water during Cruise AK-47, and focus on the air-sea exchange of hexachlorocyclohexane (HCH) in the Bering and southern Chukchi Seas. Hexachlorocyclohexane is an insecticide used throughout the world and is available in two fomiulations. technical-HCH and lindane. Technical-HCH is a mixture of five isomers in the following proportions (Metcalf, 1955): a 55-80%; (3, 5-14%; Y. 8-15%; 5, 2-16%; and e. 3-5%. Although all isomers are toxic, only the gamma isomer is insecticidal, and it is produced in pure form as the insecticide lindane. The limited data available about the tonnages of HCH used in Northern Hemisphere countries are summarized in Table 1. Most listings are from the United Nations Food and Agricultural Organization Production yearbooks (FAO. 1985, 1987). These should be considered lower limits of actual usage because many countries do not report such statistics to the FAO. Nevertheless, a usage pattern of technical-HCH in Asia and lindane in Europe can be seen. No use of technical-HCH in Europe during the 1980's is reported by the FAO. Technical-HCH has not been used in the United States since 1978, when manufacturers canceled their registrations or switched them to lindane, which is still registered for application (EPA, 1980a.b, 1985). The Soviet Union currently uses a fortified mixture of HCH that consists of 90% y-HCH with the balance composed of the other isomers (IRPTC, 1983). TABLE 1 Usage of HCH. Metric Tons/y Technical Country Year(s) HCH Lindane Reference India 1979-1981 21,390 283 FAO, 1985, 1987 India 1984-1986 24,412 - FAO, 1985, 1987 Turkey 1979-1982 1,695 75 FAO. 1985, 1986 Mexico 1979-1985 220 31 FAO. 1985. 1987 Italy 1979-1985 - 1,556 FAO, 1985, 1987 Poland 1979-1985 - 138 FAO, 1985, 1987 Pakistan 1979-1982 138 - FAO, 1985, :987 Japan 1948-1970 18.180 Tanabeefa/.. 1982 Peoples Republic of China - 20,000 Tanabeer«/.. 1982 Hungary 1979-1982 - 456 FAO, 1985, 1987 Scandinavian Pacyna & Oehme, Countries - - 29 1988 USA 1972-1976 48 335 EPA, 1980 The deposition of organic compounds from the atmosphere is controlled by their physical properties. Vapor pressures and water solubilities of the HCH's are sufficiently high that they remain primarily as gases in the atmosphere or dissolved in the water column with relatively small fractions sorbed onto particles (0.5-2.5%) (Tanabe & Tatsukawa, 1983; Bidleman, 267 1988;H;irgravee/a/., 1988). Taken together, the HCH isomers are the most abundant of the heavy organochlorines in northern troposphere and surface waters. As a result, low volumes of air (10-20 m^) are sufficient for the analysis of a-HCH, and a-HCH and y-HCH can be determined in 2-4 1 water. A knowledge of air and surface water HCH concentrations, along with the appropriate Henry ' s law constants and wind speed, allows the flux of HCH's across the air-sea interface to be calculated. For these reasons, the HCH's are appealing compounds for studying the air-sea exchange of a high molecular weight gas. Previous studies of air-seaexchange of halogenated organic gases have examined freons and low molecular weight chlorinated hydrocarbons such as CCI4 and CHCI3 (Hunter-Smith et al., 1983; Khalil et al., 1983; Singh e/ a/.. 1983). Experimental Methods Cruise Track Cruise AK-47 originated and terminated at the deep-water port of Dutch Harbor, Alaska, and lasted from 26 July- 2 September 1988. Surface (2 m) water concentrations of a-HCH and y-HCH determined at 19 stations of the AK-47 cruise, and air concentrations of a-HCH and hexachlorobenzene (HCB) were measured at 16 stations. Hexachlorocyclohexane and other OC concentrations in the microlayer (top 120 ^ m) and surface water (2 m) were compared at one station. Four high volume air samples were taken for y-HCH, heptachlor epoxide (HE), trans-chlordane (TO, cis-chlordane(CC),trans- nonachlor (TN), cis-nonachlor (CN), p,p'-DDT, o,p"-DDT, p,p'-DDD, p,p'-DDE, polychlorinated biphenyls (PCB), and polychlorinated camphenes (PCC). Sample Collection Surface water was collected using a sampler based on a design by Keizer ef a/. ( 1 977 ). This was constructed using two empty 4-1 glass bottles in protective plastic casings (Solvent bottle carriers, Nalgene Corp.) mounted on a wooden frame. Teflon elbows were cemented into the bottle caps, with a glass tube connecting the two bottles through the elbows. A messenger sent down the wire broke the glass tube, allowing water to fill the bottles within 5 min. Microlayer water samples were collected at one station from a small boat at least 1 km from the ship using a stainless steel screen (Garrett, 1965; Rice et al. 1982). At each station the surface water temperature and salinity were noted from a conductivity/temperature/depth (CTD) probe, and wind speed was taken from the ship's meteorological station. Low-volume air samples were taken using a pressure- vacuum pump (Millipore Corp. ). Air w as pumped through two or three polyurethane foam (PUF) plugs (4.8-cm diameter, 3.2-cm thickness) in a thick-walled glass tube (4.0-cm ID, 15-cm length) for 8-24 h at a flow rate of 20 1/mm, yielding volumes of 9.2-28.3 m'. Flow rates were monitored using an in-line Top-Trak Model 820 mass flowmeter (Sierra Instruments). Because of the low air volumes only a-HCH and HCB were quantified with this system. High volume air samples were taken using a Rotron DR-313 brushless pump. The air was pulled through a 20 X 25-cmGelmanAEbinderless glass-fiber filter (OFF) and two 7. 8-cm diameter x 7.5-cm thick PUF plugs at a flow rate of 0.4-0.5 mVmin for 3 days to yield 1.790-2,160 m' air. Details of this system are provided by Billings and Bidleman (1980. 1983). In both high and low volume systems breakthrough of analytes from front to back PUF plugs was monitored by the separate analysis of each plug. Samples and field spikes were immediately analyzed on board ship or were stored in a freezer (-20°C). Field high and low volume air sample spikes were prepared by pipetting 1.0 ml of a calibration standard containing 8-17 ng/ml organochlorine pesticides (OC) onto clean PUF plugs. Blank PUF's and GFF's were brought to the ship and returned with the samples. Water spikes were prepared by pipetting 1.0 ml of a calibration standard containing 10-17 ng/ml a-HCH and y-HCH in acetone to 3.5 1 water and extracting the spike using the method described below. Concurrent analysis of ambient water concentrations was done and the spike experiments were corrected for ambient HCH levels. Preconcentration and Cleanup Analytes from 3.5 I water were preconcentrated by two methods: liquid-liquid extraction into 300 ml dichloromethane (DCM) and adsorption onto Cg bonded-phase cartridges ( Hinckley & Bidleman, 1989). The C, bonded-phase cartridges were eluted with 3 ml 1:1 ethyl ether-hexane. Polyurethane foam plugs were extracted for 6-8 h in a Soxhlet apparatus with petroleum ether. Glass-fiber filters were cut into strips, placed in round-bottom flasks and refluxed in DCM for 8 h. All sample extracts were reduced and transferred to hexane or isooctane by rotary evaporation and nitrogen blowdown. High volume air samples were split into two fractions using a column of silicic acid and neutral alumina (Keller & Bidleman, 1984; Bidleman et al., 1987). All extracts were treated with concentrated sulfuric acid for cleanup before gas chromatographic (GC) analysis. Gas Chromatographic Analysis Gas chromatographic analysis of air and water samples .was done using a number of detection systems. Hexachlorocyclohexanes in water, HCH"s and HCB in low volume air samples, and DDT and its breakdown products; and PCB in high volume air samples were determined by GC with electron capture detection (GC-ECD), carried out using a Hewlett Packard 5840, Varian 3700, or Carlo Erba 4160 chromatographs with '''Ni ECD's. The instruments contained 25-m bonded-phase fused silica columns (polydi-methylsiloxane, S'/r phenyl, 0.25 |i m film thickness, Hewlett Packard or SGE Corp.). Carrier gases were hydrogen or helium at 30-40 cm s ', the injector temperature was 240°C and the detector was 320°C. Samples were injected using a Grob technique (30 s split time). Chromatographic data were collected using the HP-5840 integrator, a HP-3390A. or Shimadzu Chromatopac CR3A integrator. 268 Two types of mass spectrometry were used for the analysis of high volume air samples. The HCH's, TC, CC, TN, HE, p,p"-DDE and p,p'-DDT were determined by gas chromatography-electron impact mass spectrometry (GC-EIMS) using a Hewlett Packard 5890 GC with a 5970 mass selective detector. The instrument contained a 3()-m bonded-phase silica column (6% cyanopropylphenyl, 0.25 |i m film thickness, J & W Scientific). The carrier gas was helium at 30-40 cm s'; the injectorand transfer line temperatures were 240°C and 250°C. A 3 m Grob time was used for these analyses. Multiple ion detection ( MID ) employing the following ions was used: HCH 217, 219; HE 353, 355; TC and CC 373, 375; TN 407, 409; p,p" -DDT 235, 237; and p,p' -DDE 246, 248, 316,318. TC, CC, TN, CN, and PCC's were determined by GC- negative ion mass spectrometry (GC-NIMS) with MID using a Finnigan 452 1 C fitted with the same type column as was used for GC-ECD. The carrier gas was helium and samples were injected splitless (3 m Grob time). The ion source was maintained at 80°C and methane at 0. 18 torr was used. Ions monitored were: TC, CC, TN, and CN: 300, 302, 334. 408, 4 10, and 444; PCC's: 309, 311, 343, 345, 379, 381. 413, and 415 (Bidleman <>/«/., 1987). Air-Sea Equilibration of HCH When HCH is at equilibrium between the atmosphere and surface water: N = Ko.AC (4) C,/Cw = H/RT = Kh where C,^ and C^ are the concentrations of HCH in air and water, respectively (mol m '), R is the gas constant (8.2 X lO'atmm'mol ' K' ), T is the temperature in Kelvin, H is the Henry's law constant (atm m' mol '), and K,, is the dimension exchange constant between the atmosphere and surface water. Equation 1 is an expression of Henry's law. H was determined in the laboratory for a-HCH and y-HCH over the range of environmental temperatures in seawater using a gas stripping method (Mackay ei al., 1979) and a dynamic headspace method (Yin & Hassett, 1986). Details of these experiments are found in Hinckley (1989). The temperature dependence of H for a-HCH in seawater is log H (atm m' mol ') = (-31381 174)/T -i- (5.61 ±0.66) (2) and for -HCH the relation is; log H (atm m' mol ') = (-3183 ± 99)/T + (5.29 ± 0.34). (3) A two-layer model has been proposed for the study of gas exchange between air and sea (Liss & Slater. 1974). In this model an air film lies above and a water film below the interface. Transport of HCH through the interface occurs by molecular diffusion across the concentration gradients in both the air and water films. Usually resistance in one film dominates the exchange across the interface. Fick's first law applies to the fiux of HCH across the air-water interface: where N is the fiux of HCH through the interface, AC the difference in HCH concentration between the air at the interface and the well mixed troposphere, and K<,,\ is the overall exchange constant that includes resistances in the air and water films. Since the ratio of resistances to gas exchange for HCH between the air and water phase, R^w>100 (Hinckley, 1989), KoA is essentially the same as k,^ (exchange constant for the air phase, m s '). Assuming that the concentration of HCH in interfacial air is in equilibrium withC^, introduction of Equation 1 leads to N = k, (K„Cw - CJ. (5) According to Equation 5, a negative flux is from air to sea and a positive flux is from sea to air. Mackay and Yeun ( 1983) developed an equation relating kA(ms ') in the environment to the wind speed (m s ') at 10 m (U|n) and the gas phase Schmidt number (Sc): k^(ms') = 46.2 x 10'^(6.1 -h0.63U,„)"'U|oSc' (6) Using a procedure similar to that of Mackay and Yeun (1983), Sc was calculated for HCH, which was found to be independent of temperature, equal for both isomers of HCH, and equal to 2.9. Calculations for k^ were done by using Equation 6 for the locations listed in Table 5 and ranged from (1) 1.2 X 10' m s' at Station 110 (53°56'N, 175°58'E) to 1.0 X loams' at Station 100(64°23'N. 169°09'W). Detailsof these calculations can be found in Hinckley (1989). Results and Discussion Quality Control Spike recoveries of 10-17 ng HCH in water, 17 ng HCH from PUF (low volume air system), and 7-8 ng of chlordanes, and HCH and DDT's from PUF (high volume air system), shown in Tables 2a and 2b, ranged from 64 to 119%. Concentrations reported in this paper have been corrected for recovery. Breakthrough from front to back PUF (100 x back PUF/front PUF) averaged 1 8% for -HCH and 1 2% for HCB in the low volume air collection. Breakthrough for a-HCH and y-HCH ranged from 10-50% and 2-12% respectively in high volume air collection. Breakthrough of the chlordanes ranged from 1-5%, p,p'-DDT and p,p'-DDE 1-2%, o,p'-DDT 6%, and p,p'-DDD 13%. Concentrations reported are the sum of front and back PUF. Limits of detection (LOD) (Tables 2a,b), based on analysis of blank cartridges (Hinckley & Bidleman. 1989). analysis of liquid-liquid procedural and control blanks, and PUF plugs, were 0. 1 0 ng/1 for a-HCH and y-HCH in water. 20 pg/m' in air for a-HCH by ECD (low volume system), and 0.2-0.3 pg/m' for chlordanes by MS and HCH's and DDT's by ECD in the high volume system. Since the levels of y-HCH in air were only about three times the LOD with the low volume system. y-HCH was only quantified in the high volume air samples. 269 TABLE 2a Spike recoveries and limits of detection for water and low volume air samples. Sample ng a-HCH Type Spiked <7f Recovery LOD" Y-HCH % Recovery LOD- Water" 10-17 119.95,81(98^ 0.10 ng/L 89,87,82(86)^ 0.10 ng/L Air 17 85.76(80)' 20pg/m' a. LODbyECD. b. Preconcentration by liquid-liquid and bonded-phase extraction. c. Mean. TABLE 2b Spike recoveries and limits of detection for high volume air samples Pesticide ng Spiked % Recovery LOD a-HCH 7 64.67(66)-' 0.2 pg/m'" Y-HCH 7 67,82(74)- 0.2 pg/m'" TC 8 80,85(82)-' 0.3 pg/m" CC 8 75, 83 (79)-' 0.2 pg/m" TN 8 77,99(88)- 0.2 pg/m-'' p.p"-DDE 8 99,94(97)- 0.2 pg/m'" p,p -DDD 8 79,82(81)- 0.2 pg/m* o,p -DDT 8 94, 100(97)- 0.3 pg/m* p,p-DDT 8 91,94(93)- 0.3 pg/m* a. Mean. b. LODby ECD. The HCH " s mean concentrations in high volume air samples detemiined by ECD and EIMS and chlordanes deteimined by EIMS and NIMS are not significantly different (Table 3b) (t-test, a= 0.05). Alpha-HCH was quantified using both the low and high volume air collections. Comparison of the average concentration of CrHCH by both methods reveals no significant differences (t-test, a = 0.05) in mean concentrations, 266 pg/m' by high volume and 25 1 pg/m' by low volume. Liquid-liquid extraction and C„ cartridge methods of preconcentration were compared at four stations. Concentrations of a-HCH averaged 2.57 ± 0.16 ng 1 ' by extraction and 2.60 ± 0.12 ng 1 ' by bonded-phase cartridges, with no significant differences (T-test, a= 0.05). Similarly, y-HCH averaged 0.70 ± 0.09 ng 1' using extraction and 0.61 ±0.07 ngl' using bonded-phase cartridges, again revealing no significant differences. As comparable levels of HCH were found regardless of the preconcentration method, water at all remaining stations was analyzed using the liquid-liquid extraction method. Atmospheric OC Concentrations Airborne OC concentrations for the HCH's, chlordanes, and FCC found over the Bering and Chukchi Seas are listed in Table 3, DDT' s and PCB in Table 4, both using the high volume system, and Table 5 shows concentrations of HCB and a-HCH for the low volume system. Concentrations of HCB and the HCH's found over the Bering and Chukchi Seas are compared with literature values in Table 6. Concentrations of a-HCH were 200 pg m ' lower in the Bering and Chukchi Seas than in the Beaufort Sea, and y-HCH was 25 pg m ' higher than levels found in the Beaufort Sea in 1986 and 1987 (Patton et ai. 1 989 ). Tanabe and Tatsukawa (1980) determined atmospheric concentrations ofHCHoverthe Bering Sea in July 1979. They reported the mean Z HCH as 920 pg/m' with a wide range of 460-1 ,700 pg/m', higher than the mean Z HCH found duting thiscruise of 323 pg/m'. The a-HCH/y-HCH atmospheric ratio has been suggested as a "marker' for recent atmospheric transport of these pollutants (Pacyna&Oehme, 1988). During this expedition, the a-HCH/y-HCH ratio ranged from 2.0-3.7 and averaged 2.9. This is much lower than the value of 18 found in the Canadian Arctic in August 1986 (Patton et ai. 1989). Pacyna and Oehnie (1988) referred to low a-HCH/y-HCH of 1 —1 as a "European" source. Five-day back air trajectories for 6 of the days at sea (Fig. 1 ) show much of the sampled air to have been over the Soviet Union (trajectories D,E,F); however, no differences in a-HCH/y-HCH were observed for air masses from the North Pacific (trajectories B and C, a/y=3.3) compared to those passing over the Soviet Union (trajectories D,E,F,04'y=3.1). Pacyna and Oehme( 1988) suggested that high a-HCH/y-HCH ratios (>100) found at Ny Alesund in the Norwegian Arctic niay implicate a source froin the Soviet Union, which is inconsistent with reported use of the 90% lindane formulation in the USSR (IRPTC, 1983). 270 Collection Date TABLE 3a High volume air collection data. Sample Start Stop m' Air 26-31 July HAIR! 53-\'i8'N, 166°30'W 8-11 August HA1R2 65"40'N, 165°60'W 19-22 August HAIR3 65°40'N, 168°30'W 23-26 AuLHisl HA1R4 63'^75'N. 17n°00'W 58°3rN. 174°30'W 2,089 67°44'N, 168°26'W 2.161 64°23'N. 169°09'W 1,790 54°25'N. 176°44'E 1,988 TABLE 3b Airborne HCH's, ehlordanes. and PCC measured over the Bering and Chukchi Seas in 1988-' (pg/m'). Sample a-HCH y-HCH HE TC CC TN CN PCC ECD ElMS ECD ElMS ElMS EIMS NIMS ElMS NIMS EIMS NIMS NIMS NIMS HAIRI 192 356 58 91 I.I 5.3 3.2 6.1 3.3 2.7 1.8 0.21 49 HAIR2 245 ^10 57 III 0.7 1.9 1.8 2.4 2.5 1.2 1.3 0.16 38 HAIR3 358 210 84 74 1.4 4.1 2.8 4.1 3.5 1.9 1.9 0.16 34 HA1R4 291 163 71 33 1.9 -> 1 1.4 "> T 2.0 0,9 0.9 0.15 30 mean 272 261 68 77 1.3 3.4 2.3 4.2 2.8 1.7 1.5 0.17 38 sd 70 90 13 33 0.5 1.6 0.8 1.9 0.7 0.8 0.5 0.03 8 a. Based on GC-EIMS and/or GC-NIMS except a-HCH and y-HCH which was GC-ECD and GC-EIMS. b. PCC calculated as toxaphene. TABLE 4a Airborne DDT's ovei 'he Bering and Chukchi Seas in 1988. Sample pg/m' p.p i-DDT o,p'-DDT p,p-DDD p.p-DDE I-DDT HAIRI 26 14 3.0 3.0 46 HAIR2 19 7.6 3.6 8.2 38 HA1R3 39 15 8.2 12 73 HA1R4 14 4.6 4.1 11 34 mean 25 10 4.7 8.6 48 sd 11 5 2.4 4.0 18 I ABLE 4b Airborne PCB over the Bering and Chukchi Seas in 1988. Sample pg/m" Light' Heavy" Total' Total'' HAIRI 532 649 1,180 900 HAIR2 481 456 904 760 HAIR3 398 710 1,110 867 HAIR4 809 521 1,330 1,141 mean 555 584 1,130 917 sd 178 116 177 161 a. Calculated as Aroclor 1242. b. Calculated as Aroclor 1254. c. Sum calculated as Aroclors. d. Sum calculated as individual congeners. 271 TABLE 5 Low volume air collection data and airborne a-HCH and HCB over the Benng and Chukchi Seas in 1988". Collection PI g/m Date Sample Start Stop m' Air a-HCH ' HCB 29 July LAIRl 57°30'N. 174°30'W 57°30'N. 174°30'W 13.9 264 216 29-30 July LAIR2 57°56'N, 175°04'W 57°56'N, 175°04"W 27.5 252 228 1-2 August LAIR3 60°30'N. 177°30'W 6r20'N, 176°10'W 15.9 156 144 2 August LAIR4 61°20'N, 176°10'W 61°30'N, 178°40'W 14.1 276 228 2-3 August LAIR5 62°50'N, 179°30'W 62°30'N, 174°00"W 27.4 216 228 6-7 August LA1R6 64°00'N, 175°00'W 63°00'N, 173°00'W 27.3 276 180 9 August LAIR7 67°00'N. i73°oaw 67°45'N, 171°00'W 13.6 192 324 10 August LAIRS 68°25'N. 169°00'W 68°10'N, 168°29'W 13.7 252 264 1 1 August LAIR9 67°40'N. 165°43'W 67°44'N, 168°26'W 12.8 168 192 12-13 August LAIRIO 67°42'N. 172°00'W 67°17'N. 166°43'W 27.2 228 216 15 August LAIR 11 66°33'N. 168°36'W 66°00'N. 169°00"W 13.5 144 144 17-18 August LAIR 12 64°29'N, 165°24'W 64°29'N, 165°24'W 28.3 360 192 20 August LAIR14 65°14'N, 169°21'W 64°55'N. 168°00'W 11.5 228 156 22 August LAIR15 64°23'N, 169°09'W 64°20'N, 167°25"W 12.4 288 192 23 August LAIR16 63°5rN. 169°12'W 64°15'N. 170°50'W 12.5 240 180 26 August LAIR 17 54°25'N. 176°44'E 54°3rN. 175°28'E 9.2 312 204 27 August LAIR18 53°55'N. I75°58'E 53°55'N, 175°58'E 9.5 408 276 a. Based on GC-ECD. N 17 17 range 144-408 144-324 mean 251 210 Table 6 Comparison of HCH and HCB in Arctic Air. (pg m') Location HCB a-HCH 7-HCH IHCH Bering Sea, 1988 This Study range 144-324 144-408 57-84 201-492 mean 210 251 68 319 Bering Sea, 1979-' - - - 540- 1 ,700 Beaufort Sea." 1986-87 >1 19-233 283-731 24-53 324-767 Beaufort Sea,' May-June. 1986 73 425 70 495 Aug-Sept, 1986 63 253 17 270 Spitzbergen'' Fall, 1982-83 75-227 407-1,416 0.1-6 - *W/S, 1983-84 29-389 121-787 12-102 - Summer, 1984 20-201 260-774 24-100 - Bear Island'' Fall, 1982-83 78-200 277-1,550 0.1-67 - *W/S, 1983-84 87-201 110-469 23-80 - Summer, 1984 42-149 38-305 5-41 - Hope Island' 1 1982-83 100-200 250-1,700 <5-75 ( Jan Mayen'' t 1982-83 50-200 400-1,600 <5-50 - a. Tanabe & Tatsukawa, 1980 b. PMon etal., 1989 c. Hargrave f/ a/., 1988, mean values d. Pacyna & Oehme, 1988 e. Oehme &Ottar, 1984 Winter/Spring 272 r ' I » \ f— ^-^ -^.-v- 'N \ _- 'V 60° N ^ 160 E 170^ 18p°E '■/ ~- _L Fig. 1. Five day back air trajectories during Cruise AK-47. Location the samples were taken, and the termination of the air trajectory: □ 925 mb trajectory. O X.'iO mb trajectory. Each symbol denotes a six hour period. Following is the date of the sample and corresponding air: A, July 30, 1988-LAIR2, HAIRl : B. August4, l988-LAIR5:C.Augusl7, 1988-LAIR6;D.Augu.st 10, 1988-LAIR8,HA1R2:E, August 13, I988-LAlR10;andF, Augu.st28, 1988-LAIR18, HAIR4. 273 TABLET Companson of Chlordanes in Arctic Air. Location TC CC (pgm') TN CN ZChlordanes Bering Sea, 1988 This Study range 1.4-3.2 2.0-3.5 0.8-1.9 0.15-0.21 mean 2.3 2.8 1.5 0.17 Beaufort Sea,-" 1986-87 0.6-3.4 1.9-5.1 0.8-5.1 0.15-0.8 Beaufort Sea,^ May-June, 1986 - - - - Aug-Sept, 1986 - - - - Spitzbergen" Fall, 1982-83 0.6-6 - - - *W/S. 1983-84 0.6-5.1 - - - Summer, 1984 1.7-5.4 - - - Bear Island' Fall, 1982-83 0.5-1.7 - - - *W/S, 1983-84 1.2-1.3 - - - Summer, 1984 0.6-2.1 - - - Hope Island'' 1982-83 1.0-2.0 - - - Jan Mayen'' 1982-83 0.5-2.0 - - - Mould Bay' June. 1984 0.5-1.7 1.1-1.8 1.0-1.5 <0.2-0.4 4.4-8.8 6.8 3.6-13 3.6 L9 2.1-3.7 a. Panon etal.. 1989 b. Hargrave««/., 1988 c. Pacvna & Oehme, 1988 d. Oehme &Ottar, 1984 e. Hoffc&Chan, 1986 * Winter/Spring Other OC's measured over the Bering and Chukchi Seas were HCB. TC, CC, TN, CN, and PCC (Tables 3b,5). Mean HCB levels were 210 pg m ', close to the values found in the Canadian and Norwegian Arctic (Table 6). The average concentration of chlordane components (TC-i-CC+TN-i-CN) was 6.8 pg m\ similar to levels found in the Canadian Arctic (Table 7 ). The average ratios of the chlordanes ( R=CC:TN:TC ) in the Bering and Chukchi were 1.0:0.46:0.81. Although the TC:CC ratio is less than unity, there appears to be more TC than TN, a reversal of the order found in northern Canada by Hoff and Chan ( 1986) (R=l .0:0.89:0.56) and Patton el al. (1989) (R=1.0:0.74:0.50). Polychlorinated camphene concentrations of 38 pg m' were fourth highest of the atmospheric pesticides and were nearly the same as those observed in northern Canada (Table 8). Surveys of OC's in fish from the Canadian Northwest have found PCC's to be the most abundant pesticide residue (Muir et al., 1988; 1990a; Norstrom et al., 1988). Levels of PCC's in fish were sufficiently high that Muir ci al. ( 1990a) noted that consumption offish and fish livers by Inuit may lead to an intake of PCC's that exceeds the US National Academy of Sciences' (1977) acceptable daily intake. Atmospheric transport has recently been suggested as the source of PCC's to the arctic ecosystem (Bidleman et al., 1989). High concentrations of the DDT' s and PCB's were found over the Bering and Chukchi Seas (Table 4). These chemicals were entering the sampling system through the front end of the sampling apparatus ( breakthrough of DDT' s from front to back PUF was 1-13%) and no system contamination of either DDT or PCB was found in the blanks. The DDT's and PCB's were confirmed by GC-MS. As Table 8 shows, concentrations of DDT' s and PCB ' s found during cruise AK-47 are significantly higher than have ever been reported in the arctic regions. Contamination of the ship with these chemicals is suggested by these comparisons. It was known that the ship had been fumigated for insects prior to the cruise and high DDT concentrations suggest that this insecticide is what was used. Hydraulic fluids, which were found all over the ship, are known to contain significant amounts of PCB's in the United States (Interdepartmental Task Force on PCB's, 1972). It is not 274 TABLE 8 Comparison of DDT's. PCB's, and PCC's m Arctic Air. Location Sum DDT (pgm ') PCB^ PCC Bering Sea, 1988 This Study range mean 34-73 48 456-710 584 30-49 38 Bering Sea, 1979" - 4.5-15 - Beaufort Sea,' 1986-87 0.5-8.9 2.1-13 21-78 Beaufort Sea," May-June, 1986 Aug-Sept, 1986 <1 <1 <2 <1 - Spitzbergen' Fall, 1982-83 *W/S, 1983-84 Summer, 1984 - 25-75 25-150 - Bear Island" Fall, 1982-83 *W/S, 1983-84 Summer, 1984 - 10-40 10-30 - Hope Island' 1982-83 - 5.0-70 - Jan Mayen' 1982-83 25-300 a. Pentachlorobiphenyl or Aroclor 1 254 b. Tanabe & Tatsukawa, 1980 c. Pattont'/«/., 1989 d. Hargrave era/., 1988, mean values e. Pacyna & Oehme, 1988 f. Oehme &Ottar, 1984 * Winter/Spring known if PCB's are added to hydraulic fluids in the Soviet Union; however, it is a reasonable assumption that they are. Consequently, concentrations of DDT's and PCB's found during cruise AK-47 and reported in this paper probably represent contamination from the ship and are not an accurate atmospheric concentration for the Bering and Chukchi areas. Wilier OC Concentrations Levels of a-HCH and y-HCH in surface water are given in Table 9 and are compared with literature values in Table 10. Kawano et at. (1988) measured HCH's in the Bering Sea in July 1981 and found concentrations of a-HCH very close to those found during Cruise AK-47, but our y-HCH concentrations are about x3 higher than those found in 1981. Tanabe and Tatsukawa (1980) reported HCH in the Bering Sea in July 1979 about 1 ng/l less than was found during this cruise. Beaufort Sea locations further north appear to have higher a-HCH concentrations (Table 6), retlecting the Beaufort Sea's higher air concentrations (Hargrave et ai, 1988; Patton et ai, 1989) and enhanced air to sea exchange in the colder water (Beaufort Sea, -2°C; Bering Sea, 5°C). No significant differences in surface water concentrations of either isomer of HCH was found between the Chukchi Sea, Chirikov Basin, or Bering Sea (Tukey's test, a= 0.05) during Cruise AK-47. Concentrations of OC's in two microlayer and one 2-m water sainple at Station 3 (57°56'N. 175°05"W) are shown in Table II. NoenhancementofHCH'sorHCB was found in the microlayer; however, TC, CC, and TN were enriched in two, and HE in one microlayer sample. Flii.x of HCH Between the Atmosphere and Surface Water The departure from equilibrium for a-HCH is shown in Figs. 2-4 for the Bering Sea, St. Lawrence Island to the Bering Strait, and the Chukchi Sea; similar results for y-HCH are shown in Fig. 3. The disequilibrium is given as C^^-C", where C^ refers to the aqueous HCH concentrations found and C" denotes the aqueous HCH concentration in equilibrium with C^ (calculated from Equation I ). Average saturation indices (SI=100*c„/c" ) in the Bering and Chukchi Seas were 86% for a-HCH and 26% for y-HCH. The disequilibrium of HCH's was previously calculated for the Beaufort Sea (Patton et ai, 1989) using Henry's law constants for the HCH's, with their temperature dependence assumed similar to the PCB's (Burkhard t'f a/., 1985). Average SI in the Beaufort Sea were 93% and 24% for the a-HCH and y-HCH. Recalculation ofC" 275 TABLE 9 Surface water (2m) collection data and a-HCH and y-HCH in the Bering and Chukchi Seas in 1988-', Date Station^ Location Water Salinity Wind Temp. (ppt) Speed (°C) (m/s) Corresponding Air (ng/l) a-HCH Y-HCH 30 July 003 57°56'N, 175°04'W 8.8 32.6 5.5 LAIR2. HAIRl 2.56 0.72 1 August 007 60°29'N, 177°52'W 7.2 32.6 4.3 LAIR3. LAIR2 2.68 0.62 2 August 009 61°20'N, 176°06'W 6.8 31.7 4.1 LAIR3, LAIR2 2.55 0.74 4 August 019 62°25'N, 174°00'W 7.6 30.9 6.8 LA1R5 2.50 0.64 5 August 024 63°4rN, 178°28'W 5.6 32.0 2.1 none 1.95 0.50 7 August 035 63°00'N, 173°00'W 7.4 30.9 6.6 LAIR6 2.62 0.41 8 August 036 63°25'N, 172°I0'W 7.3 31.6 6.7 LA1R6 2.10 0.79 9 August 045 67°44'N, 172°50'W 2.3 24.0 5.7 LAIR7, HAIR2 1.91 0.54 10 August 050 68°40'N, 168°29'W 6.1 31.7 5.1 LAIR8, HAIR2 2.33 0.6 12 August 055 67°44'N, 168°26'W 4.0 32.2 8.6 LAIR9, HAIR2 2.31 0.63 1 3 August 061 67°20'N. 169°45'W 5.1 30.3 4.9 LAIRIO 2.75 0.64 15 August 074 66°33'N, 168°36'W 2.5 32.2 4.1 LAIR 11 2.59 0.59 18 August Nome 64°29'N, 165°24'W 18.0 25.0 4.0 LAIR 12 2.83 0.49 19 August 83 65°40'N, 168°30'W 10.1 30.3 8.3 HAIR3 2.92 0.57 20 August 089 65°14'N. 169°2I'W 6.1 31.7 8.8 LA1R14 , HA1R3 2.19 0.62 21 August 096 65°05'N 170°40'W 2.1 32.7 5.9 HAIR3 1.85 0.72 22 August 100 64°23'N, 169°09'W 6.3 31.8 12.0 LAIR 15 . HA1R3 1.91 0.51 23 August 104 63°51'N. 169°12'W 5.7 32.1 2.1 LAIR 16 1.78 0.39 28 August 110 53°56'N, 175°58'E 9.7 32.9 1.9 LAIR 18 , HAIR4 2.25 0.49 a. Based on GC-ECD. N 19 19 b. Figure 1. range mean sd 1.7J S-2.92 2.35 0.36 0.39-0.74 0.59 0.11 TABLE 10 Comparison of a-HCH and y-HCH concentrations in northern water from this study with reported values. (ng/l ) Location Date a-HCH Y-HCH Reference Bering and Chukchi Seas August. 1988 2.35 0.59 This Work N. Pacific and Kawano et al.. Bering Sea July. 1981 2.75 0.17 1988 Bering Sea July. 1979 3.9" Tanabe & Tatsukawa. 1980 Beaufort Sea June. 1986 4.40 0.57 Hargravee/a/.. 1988 Beaufort Sea August. 1986 4.53 0.65 Hargraveeffl/.. 1988 Beaufort Sea June, 1987 7.1 0.81 Pattonef«/.. 1989 Hudson Bay McCrea & Fischer, Rivers 1980-81 6.42 0.86 1988 a. Sum ofa-HCH and Y-HCH. 276 _l \ CD C o s u u 0.0 -0.5 -1.0 -2.0 -a.B flIpha-HCH Equi I ibrium and Flux Bering Sea 1 10 M "i i i I 00, "-^ 003 □ Cw- C° RVE QFlux ■2D0 id: -400 o \ CD •800 flIpha-HCH Equi I ibrium and Flux St. Lawrence Island to Bering Straits 2.0 1.0 ^ 0.0 D) -1.0 o *2.0 U -3.0 J •4.0 -5.0 U Noma m 036 104 ^ Dc,-c; ose 083 r-VA aooo 1000 0 ^-1000 3) ■ara g^ •3000 •4000 •BOOO QFlux Fig. 2. a-HCHdepartureformequilibrium C„-CJ.C. = actualconcentration. C'^ = waterconcentration at equilibrium with air.Eq. l,(ngl 'landflux (Eq. 5, pg cm - yr ') over the Bering Sea. Positive numbers indicate sea to air exchange and negative numbers air to sea exchange. Station numbers are provided below the bars. Fig. 3. a-HCH equilibrium C, - CJ, ng 1 ') and flux (pg cm- yr ') from St. Lawrence Island to the Bering Strait. Positive numbers indicate sea to air exchange, negative numbers air to sea exchange. Note the increased flux relative to the Bering (Fig. 2) and Chukchi Seas (Fig. 4 1. Station numbers are provided below the bars. N O 3 U flIpha-HCH Equi I ibrium and Flux Chukcli i Sea 0.0^^ -0.5 -1.0 -1.5 074 i i Oei 055 ^ I HVE 050 045 DCw - C° 0FIUX Giomma-HCH Equi I ibrium and Flux 0.0 -n.5 r^ l_ _I -500 35 CD -1.0 W C E v_/ O -1.5 -1000 (3) Q. 0 s u -2.0 X 1 -1500^ 3 -2.5 u_ -3.0 -2000 -3.5 □ C, - CO QFlux Fig. 4. a-HCH equilibrium C„ - C". ng 1') and flux (pg cm- yr ') over the Chukchi Sea. Positive numbers indicate sea to air exchange and negative numbers air to sea exchange. Station numbers are provided below the bars. Fig. 5. y-HCH equilibrium, (C. - CJ, ng 1') and the flux of y-HCH (pgcm-yr 'l. Station numbers are below the appropriate bars. The flux of y-HCH is from air to sea. 277 TABLE 11 Comparison of pesticides in microlayer and surface water. Station 3: 57°56'N, 175°04"W. ng/1 Pesticide Microlayer' Surface Water" a-HCH 1.82,2.31 2.56 Y-HCH 0.45, 0.59 0.63 HCB <0.005 0.06 HE 0.05. 0.34 0.05 TC 0.30,0.41 0.06 CC 0.25.0.26 0.05 TN 0.13,0.10 0.03 Sample volume 3.1-3.5 I layer thickness = I20|im. Sample volume 9.5 1, depth = 2 m. in the Beaufort Sea using experimentally determined Henry's law constants (Equations 2,3) resulted in slight changes in the estimated SI to 7 1 % and 28% for a-HCH and y-HCH. Thus in the Bering. Chukchi, and Beaufort Seas the SKa-HCH )>S1(Y-HCH). The Sr s of a a-HCH and y-HCH at Nome Station (64°29'N, 165°24'W)were 155%and68%. These Si's are greater than at other stations, and for a-HCH indicate a sea to air flux. This station was very shallow (15 m) and warm (I8°C), and the salinity was low (25 parts-per-thousand) due to Yukon River input into Norton Sound. We could find no report of HCH's in the Yukon River, but average concentrations of a-HCH and y-HCH in five rivers draining the Hudson Bay lowlands were 6.4 ng 1 ' and 0.9 ng 1 ' (McCrea & Fischer, 1986). These are above average HCH levels in the open Bering Sea. Influx of HCH's via cold Yukon River water and advection of cold Bering Sea water into Norton Sound followed by solar heating could lead to higher Si's, and in the case of a-HCH, to a reversal of the flux direction. An explanation for the lower SI of y-HCH at all stations is unknown, but our results suggest a more rapid disappearance of y-HCH than a-HCH in the upper water column. The second- order base hydrolysis of lindane follows the equations (Ellington etai, 1987): and dC/dt = -kJOH] (7) In k, (L mol ' min ' ) = -8895/T -i- 30.46 . (8) A half-life of over 1,600 days was calculated for lindane at the average temperature found in the Bering Sea (5°C) and pH 8. The application of this freshwater rate constant to seawater is uncertain; however, hydrolysis alone probably cannot explain the deficiency of y-HCH in surface water. More rapid breakdown of the HCH's appears to occur by photolysis. Saleht'/ a/. (1982) determined first-order photolysis rate constants for y-HCH in purified water (Milli-Q) and three fresh waters in the pH range 7.3-9.2. Adjusted midwinter half- lives were given as 65 d in Milli-Q water and 14-150 d in the natural waters. MalyandieM/. ( 1982) reported a 48-d half-life for y-HCH in distilled water with 5-25 mg/1 added fulvic acids. Isomerization of a small percentage of y-HCH to a-HCH occurred after 15-35 d irradiation. In distilled water alone, y-HCH degraded slightly more rapidly than a-HCH. The relative photolytic stability of the two HCH isomers under arctic conditions is unknown. Fluxes of HCH's were calculated by Equation 5 for all stations with concurrent air and surface water concentrations. It is important to note that these fluxes were estimated from kj values calculated from wind speed (Equation 6) and were not directly measured. How closely these estimates represent the actual situation is unknown. Despite model predictions, Peng et al. ( 1979) found no correlation between the on-station wind speed and the flux of radon between the atmosphere and surface water in the open ocean. Exchange rates in the Bering and Chukchi Seas ranged from -99 pg cm- yr ' (air to sea) at Station 7 (60°28'N, 177°50'W) to -1681 pg cm- yr ' at Station 45 (67°44'N, 172°50'W) (Figs. 2-5). Station 45 was different from others in this region in having sea ice and a low salinity of 24 parts-per- thousand from melting ice. Average fluxes were -290pgcm-yr ' in the Bering Sea and -SlOpgcm'yr ' in the Chukchi Sea. More dynamic fluxes were estimated from St. Lawrence Island to the Bering Strait, ranging from 1 ,620 pg cm- yr -' sea to air flux at Nome (64°29'N, 165°24'W) to -4.800 pg cm - yr ' air to sea flux at Station 100 (64°23'N, 169°09'W) (average = -1,290 pg cm - yr '). This is a shallow area (40-50 m) with a complicated geometry and a relatively high flow of 1.2 Sv (Coachman & Aagaard, 1988) producing a high degree of vertical mixing that may explain the variability of flux. Average fluxes over the entire cruise were -880 pg cm - yr ' for a-HCH and -965 pg cm - yr ' for y-HCH. Atlas's (1988) "best" estimate of HCH fluxes for the North Atlantic and North Pacific Oceans were -466 to -715 pg cm - yr ' for a-HCH and - 100 to -240 pg cm - yr ' for y-HCH. Atlas arrived at these fluxes using literature values of air and surface water HCH concentrations, Henry's law constants estimated as functions of temperature, and k,=7.5x 10 'ms'. Atlas assumed an SI of 90% for both HCH isomers. Our higher estimate of the y-HCH flux results from the considerably greater undersaturation of this isomer. This work was done with support of the US Department of the Interior. Fish and Wildlife Service; the US Environmental Protection Agency. Great Lakes Program Office. Grant No. R0005027-()l; and the USSR Academy of Sciences in accordance with Activity 02.07- 2101 "Comprehensive Analysis of Marine Ecosystems and Ecological Problems of the World Ocean" under Project 02.07-21 of the US- USSR Environmental Agreement. We wish to thank Joseph Kovelich of the Canadian Atmospheric Environmental Service for doing the five-day back air trajectories shown in Fig. 1 . Contribution No. 862 of the Belle W. Banich Institute. 278 8.1.2 Migratory and Bioaccumulative Peculiarities in the Biogeochemical Cycling of Chlorinated Hydrocarbons SERGEI M. CHERNYAK, VALERIA M. VRONSKAYA, and TATIANA P. KOLOBOVA Institute oj Global Climaie and Ecology. Stale Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR Introduction Among the multiple organic compounds polluting the environment, chlorinated hydrocarbons are of great importance, especially pesticide preparations (OC"s and PCB's). These compounds, owing to their exclusive properties, were widely used in the past and they are still being heavily used in certain countries, in spite of the fact that since 1971-1972 many developed countries have imposed restrictions or even a full ban on the use of certain pesticides (forexample, DDT). In fact, the world production of these preparations has hardly reduced in the recent decade, becoming stable at approximately 1.2 million tons of PCB's (Bletchly, 1984), 3 million tons of DDT(GoIdberg, I975;Tanabe, 1 982), and about 1 million tons of lindane (Tanabe, 1985). Their use over many years has resulted in the widespread distribution of these raw compounds tha> now have become a constituent part of practically all environmental compartments including marine ecosystems (Izrael & Tsyban, 1985a), and owing to the processes of atmospheric transfer, these contaminants have now gotten into quite remote regions rather quickly (Izrael & Tsyban, 1985b). Thus, forexample, residues of PCB have been found in fish and mollusks of the Antarctic (Subramian et ai, 1987) and in penguins (Subramian ('/a/., 1985). Note that the ocean, if one may put it that way, has a role of an accumulator of chlorinated hydrocarbons since, according to Tanabe (1985 ), up to 70% of all chloroorganic compounds discharging into the environment are concentrated in marine ecosystems. Having significant molecular resistance and a high degree of affinity with lipids and suspended agents, chlorinated hydrocarbons can be accumulated in hydrobionls and transmitted along the food chain. It is determined that the process of concentration in living beings depends both on physical and chemical properties of contaminants and on peculiarities of organism and environmental conditions (Tanabe, 1985). Sea organisms not only accumulate and transform contaminants but they also transfer them into different compartments, v^hich leads to their wide distribution in marine ecosystems. In this connection, the study of the processes of chlorinated hydrocarbon accumulation and distribution in different components of marine ecosystems and the study of their interaction with the environment assume ever greater importance. Note that investigations of the mentioned processes in background regions of the ocean that do not experience the pemianent anthropogenic influence, including ecosystems of the Bering and the Chukchi Seas, are of a special significance. Materials and Methods Seawater samples, 100 1 each, were passed through resin ( XAD-2 ) at the rate of 20 1 per hour. The adsorbed chlorinated hydrocarbons were eluted using 80 ml of ethanol to which an equal volume of the 2% sodium sulfate solution was added. The water-alcohol solution was extracted twice with n-hexane ( 25 ml ). The extract was concentrated with the rotary evaporator to 4-5 ml volumes; it was then purified by mixing it with concentrated sulfuric acid, neutralized with a 5%-NaHCO, solution, washed with the water, dried over sodium sulfate, and concentrated by evaporation with pure nitrogen gas to a volume of I ml. The concentrate was then injected into a Hewlett- Packard 5840A gas chromatograph with an autosampler. The chromatography was performed under the following conditions: a capillary 30 m fused quartz column with the 0.32 internal diameter; a DB-1 chromatography phase (0.25 |i m). The analyses were carried out under the conditions of column thermostat temperature programming: the starting temperature was 1 20°C for 1 min, the programming rate was 5°C/min up to 250°C. The chromatography time was 40 min. The injector temperature was 225°C; the electron capture detector temperature was 300°C. Based on tests of this method, it was found that the overall approach produced results that were within 1 5-20% of the expected values for the concentrations of chlorinated hydrocarbons in seawater. The bottom sediments were centrifuged for 20 min at a speed of 2,000 rpm to completely separate the silt from the water, then they were extracted with acetone, followed by a shaking with a hexane-acetone mixture (3: 1 ). The combined extract was mixed with an equal volume of the 2% sodium sulfate solution. The hexane layer was separated and the water-acetone layer was subjected to reextraction. The combined hexane extract was concentrated and then purified by mixing it with sulfuric acid to remove organic substances and with tetrabutylammonium sulfate to remove sulphur and sulfur-organic compounds. The purified solution was 279 concentrated in the flow of high-purity nitrogen gas to 1 ml and subjected to the chromatography analysis. The accuracy of this method was about 50%; therefore, the observed results should be interpreted only qualitatively. The samples of the marine biota were first separated from their shells (crabs, bivalves, urchins, etc.) and the soft tissues ground into a homogeneous mass, defatted with acetone, and subjected to preliminary processing similar to the analysis of bottom sediments. Simultaneously, separate subsamples were weighed for the determination of dry weight and fat content. Recoveries in these experiments were in the 93-97% range. The suspended materials were secured by filtering large water volumes (up to 300 1) through 0.45 |a m pore diameter membrane filters, which were previously cleaned with organic solvents. The chlorinated compounds were extracted from the suspended materials on these filters by extracting them with n-hexane in Soxhlet concentrators over 4-h periods ( 10 cycles per hour); thereafter, they were analyzed similarly to the seawater samples. Results and Discussions Table 1 presents the data on the concentration of chlorinated hydrocarbons in water of the Bering and Chukchi Seas. The comparative analysis of these findings shows the peculiar distribution of each of the studied xenobiotics. The most interesting results are for the hexachlorocyclohexanes. Thus, it is found that their concentration in water samples exceeds by approximately 10 times the concentration of other identified chloroorganic hydrocarbons such as PCB's and DDT's. These rather high concentrations of HCH isomers (up to 5 ng/1) with their low concentration in the atmospheric air samples TABLE 1 The concentration of chlorinated hydrocarbons in the seawater. Chlorinated hydrocarbon concentration (ng/1) cis- tr- tr- Stat. a-HCH P-HCH y-HCH pp'-DDE pp'-DDD pp"-DDT PCS clrdn clrdn nchl 3 2.33 0.44 0.99 0.008 0.001 0.003 0.2 0.005 0.004 0.002 7 2.45 0.52 1.32 0.005 0.002 0.002 0.3 0.004 0.003 0.001 9 2.15 0.12 1.48 0.002 0.002 0.003 0.2 0.004 0.004 0.001 13 1.64 0.35 0.75 0.007 0.001 0.002 0.4 0.008 0.006 0.002 15 1,20 0.62 0.62 0.006 0.001 0.002 0.2 0.004 0,003 0.001 18 1.40 0.09 0.44 0.005 0.001 0.001 0.3 0.005 0.003 0.001 22 1.40 0.19 0.59 0.003 0.002 0.003 0.2 0.008 0,005 0.003 24 1.76 0.23 0.36 0.007 0.002 0.006 0.8 0.007 0,007 0.002 26 1.58 0.32 1 .25 0.009 0.002 0.007 0.4 0.008 0.006 0.002 27 1.67 0.54 0.99 0.002 0.001 0.002 0.2 0.009 0.007 0.002 32 1.80 0.42 1.12 0.004 0.002 0.003 0.3 0.004 0.003 0.001 36 1.91 0.82 1.25 0.005 0.001 0.002 0.4 0.003 0.002 0.001 41 1.64 0.44 1.02 0.009 0.002 0.007 0.8 0.007 0.006 0.003 45 1.40 0.04 1.12 0.005 0.001 0.003 0.2 0.007 0.007 0.003 47 1.26 0.88 0.75 0.002 0.001 0.002 0.6 0.008 0.009 0.002 49 2.02 1.09 1 .02 0.005 0.001 0.002 0.7 0.007 0.008 0.002 50 2.38 0.73 1.30 0.004 0.001 0.004 0.8 0.004 0.003 0.001 53 2.50 0.64 1.12 0.012 0.002 0.006 0.7 0.004 0.002 0.001 55 2.78 0.92 1.17 0.005 0.001 0.003 0.2 0.005 0.009 0,001 57 2.54 1.13 1.12 0.002 0.001 0.002 0.4 0.007 0.005 0,004 59 2.50 1.21 1.59 0.003 0.002 0.003 0.2 0.004 0.003 0,001 61 3.02 0.95 1.87 0.011 0.002 0.007 0.6 0.008 0.006 0.002 64 2.18 0.71 0.59 0.006 0.001 0.005 0.8 0.008 0.005 0.004 67 1.80 0.55 0.31 0.004 0.002 0.004 0.6 0.009 0.005 0.009 69 1.40 0.38 0.28 0.001 0.001 0.003 0.5 0.004 0.003 0.001 72 1.01 0.68 0.13 0.002 0.002 0.007 0.2 0.004 0.003 0.001 74 3.. ^4 0.44 0.67 0.002 0.002 0.004 0.2 0.009 0.006 0.002 82 2.65 0.52 1.17 0.002 0.003 0.005 0.2 0.008 0.007 0.002 86 2.12 0.23 0.95 0.011 0.002 0.007 0.4 0.008 0.006 0.002 89 2.12 0.64 1.02 0.011 0.003 0.004 0.6 0.007 0.004 0.004 96 1.98 0.38 0.86 0.012 0.004 0.004 0.5 0.008 0.005 0.004 100 1.89 0.52 0.71 0.006 0.001 0.003 0.8 0.009 0.006 0.003 104 1.64 0.68 0.25 0.006 0.001 0.005 0.5 0.008 0.005 0.002 106 1.58 0.88 0.48 0.006 0.009 0.008 0.7 0.007 0.003 0.005 280 (according to the Ameiican specialists) were revealed for the first time in these arctic regions remote from human activities. Also, it was found that the concentration of HCH isomers in the Chukchi Sea water was 20 to 25% higher compared with the Bering Sea water (Table 1 ). These data can be explained with the Henry's law for volatile compounds. Such compounds as HCH isomers with relatively high volatility at low temperatures are usually dissolved in the water, and when temperatures rise they change into the gas phase. Since the Bering Sea water is generally warmer than the Chukchi Sea water, the Bering Sea water should retain less of these compounds ( assuming they both have the same levels overlying them in the air). The data on the study of the HCH isomeric composition confirms (3 to 4 times excess of the alpha-isomer concentration over the gamma-isomer concentration) that the main source of the HCH discharge into these regions is atmospheric from Southeast Asia where the hexachloran preparation with the 35% alpha-isomer concentration is mainly used. In the USSR and the USA, whose shores are washed by the Bering and the Chukchi Seas, only the lindane preparation with 98% of gamma-isomer is used. A number of interesting conformities to natural laws can ' be derived from a study of the distribution of the DDT group compounds in this investigated-region water (Table 1). First of all, DDT and its metabolites, DDD and DDE, are the only group of chlorinated hydrocarbons whose concentration in the Bering Sea has declined considerably since 1984 (from 0.8 ng/1 down to 0.01 ng/1 on average). In fact, the concentration of the DDT group compounds in a number of samples was at the level of minimum detection limit of the method which was, respectively for each analyte reported in Tables 1-4, the lowest value which could be reported for the number of significant digits reported (e.g.. if the results were presented as 2. 1 ng/g, then the detection limit for this column of data was 0.1 ng/g). The contamination of marine ecosystems with polychloro- biphenyls excites serious apprehension. These contaminants are a mixture of 209 different components having multiple physical and chemical properties. Every congener undergoes transformation processes at different rates and in different directions depending on the environmental conditions. As our investigation showed, the general PCB concentration did not change significantly over the last 5 years (1984-1988) remaining at the0.7to0.8ng/llevels(Tables 1,2). Furthermore, in addition to looking at total PCB' s, individual PCB congeners were also identified in all of the samples. Measuring the individual congeners provides additional information about the chemical and physical processes that interact to distribute the separate components of the PCB mixtures within each of the environmental compartments that were investigated. The comments that follow are some of the preliminary conclusions that resulted from these data. Of the total mix of possible hexa- through monochlorobiphenyls, di- and trichlorobiphenyls were the most abundant in the water samples. These data demonstrate, firstly, the primary accumulation of the more soluble components of the PCB's were appearing in the water and, secondly, the intensity of photochemical process in this geographic region appeared to be causing the formation of many low-chlorinated components. The results of the study relating to the general mix of CHC s identified, also allowed identification of new compounds that were not found earlier in these regions — viz. , cis-chlordane, trans-chlordane, cis-nonachlor, trans-nonachlor, and oxychlordane. These compounds are mainly used in temperate latitudes of the globe for control of termites and other insects. Their appearance in this arctic region, therefore, appears to occur as a result of long-distance atmospheric transfer processes. Their concentration in the water reaches the 0.02 ng/1 level (Table 1 ), with cis-chlordane and trans-chlordane usually making up most of the total; in many samples it exceeded the concentration of even the widely-used pesticide DDT, and in a number of cases it equaled the PCB concentrations. In the study of vertical distribution of chlorinated hydrocarbons, it was found they all reached depths of a few thousand meters (Table 2). The distribution of PCB's and DDT's was uniform while the HCH isomer concentrations TABLE 2 The vertical distribution of chlorinated hydrocarbons in the Southern Bering Sea (South Polygon). Chlorinated Hydrocarbon Concentration (ng/1) Depth (m) a-HCH P-HCH Y-HCH p,p"-DDE p,p'-DDD p,p'-DDT PCB 0 2.29 0.38 1.11 0.003 0.002 0.002 0.3 10 2.25 0.4 1.05 0.003 0.002 0.003 0.4 100 1.15 0.28 0.55 0.005 0.003 0.003 0.5 200 1.21 0.31 0.48 0.005 0.006 0.005 0.5 1000 0.95 0.12 0.40 0.006 0.005 0.005 0.4 3850 0.40 0.05 0.27 0.004 0.003 0.003 0.2 281 decreased sharply depending on the depth. It is considered (Tanabe. 1985) that the circulation of water masses and biogenous sedimentation (one of the most important processes for contaminant removal from the ocean surface layers) contribute to the passing of chlorinated hydrocarbons through the deep-water layers of the aquatic system. Investigation of the ice sample in the Chukchi Sea show that the concentration of HCH isomers reaches 3.4 ng/1, the DDT amount reaches 0.016 ng/1 and the PCB amount reaches the 0.9 ng/1 level. The availability of chlorinated hydrocarbons was identified in practically all samples of suspended matter (Table 3 ). Thus, using these data, it was found that the DDT accumulation coefficients ( DDT concentration ' n the suspended matter/DDT concentration in the water) for the suspensions were greater than 100 and even reached as high as 1,000 in some of the surface collections. The analyses of the suspended matter also showed that the HCH isomers are mainly in a dissolved state while the PCB concentration is evenly dispersed between two phases. It was also noted that the dissolved PCB forms usually included components with a low number of chlorine substituents, and the adsorbed forms mainly consisted of components with a larger number of chlorine substitutions. When studying the deepwater samples, however, and the relationship between the concentration of the adsorbed forms, the reverse correlation was found out — that is, the lower the level of chlorinated hydrocarbons dissolved in the water, the more was their affinity with the suspended phase. Therefore, the agents with low water solubility — for example, DDT's and highly chlorinated PCB ' s are sorbed by the suspended matter and easily transferred from the surface layers to the deep ones. At the same time, this process for low-chlorinated PCB's (the more soluble forms) ; nd lindane is less active. Based on the suspended sediment data it was also found that the fraction of sorbed chloroorganic compounds increases with the transition to the higher latitudes where the volume of the suspended agents was higher. Chlorinated hydrocarbons were also identified in all samples of plankton and neuston (Tables 4,5). Note that the accumulation coefficients in zooplankton were 10,000 to 100,000, and the absolute concentration was 45 to 90 ng/g of fat. The PCB accumulation coefficients in samples of plankton and neuston also ranged from 1,000 to 100,000. In contrast with the suspended solids, there was a more even concentration of all polychlorobiphenyl components in samples of plankton and neuston, which can evidently be explained by their overriding uniform lipophilic properties. Some residue data for chlordanes was also collected for the plankton; however, because of some methods problems, we can only qualitatively state that cis-chlordane, trans-chlordane, and trans-nonachlor appear to contribute a great amount to the total of CMC's measured in the plankton. The bioaccumulation of chlorinated hydrocarbons is even more obvious in benthic organisms (Table 6). The concentration of the DDT group in samples of benthic organisms varies from 3 to 49 ng/g of dry weight; the concentration of polychlorobiphenyls ranges from 2 to 102 ng/g of dry weight, with the PCB fractions having a balanced concentration both of low- and high-chlorinated biphenyls, and the DDT fraction had an increased concentration of 2,4'- (not reported in the tables, but indeed observed) and 4,4'-DDE components, which is evidently connected with the consumption of the partially dehydrochlorinated DDT mixture by benthic organisms. This investigation did not permit a determination of the dependence of the chlorinated hydrocarbon concentration in benthic organisms on the concentration of this material in the respective bottom sediments since contamination of the upper TABLE 3 The concentration of chlorinated hydrocarbons in suspended matter. Chlorinated Hydrocarbon Concentration (ng/g dry wt) Station a-HCH 6-HCH p.p-DDE p,p'-DDD p.p-DDT PCB 7 54 66 92 58 162 229 13 44 51 80 25 104 185 69 95 104 155 67 380 425 74 84 98 161 80 350 603 82 101 125 208 95 409 685 84 87 95 161 74 340 523 86 88 93 146 58 302 399 89 177 188 182 84 388 411 100 173 188 2\9 112 502 942 no 145 155 260 124 525 712 11.^ W 101 16fi 74 340 504 282 layer of bottom sediments was found to be rather uniform in these seas, viz., 0.3 to 3.4 ng/g of dry mass of DDT, 0.3 to 9.2 ng/g of dry mass of PCB. In conclusion, it should be noted that these experiments allow us to make a quantitative assessment of the influence of chlorinated hydrocarbons on different elements of the Bering Sea ecosystems. Therefore, on the basis of the data it was calculated that the seawater in these regions contain, at present, 1.6 t of PCB's, 32.5 t of hexachlorocyclohexanes, 42 kg of dot's, and 82 kg of chlordanes. Based on the preliminary estimated data, bottom sediments have accumulated 1.8 t of DDT' s and 6 kg of HCH" s. Thus, the following conclusion can be drawn. The PCB mass discharged into the ecosystem of the Bering Sea is distributed in equal portions between the waters and the upper layer (0-5 cm) of the bottom sediments. Dichlorodiphenyltrichloroethanes and their metabolites are mainly sorbed by the suspended solids and sedimented into bottom sediments. As regards HCH isomers, their behavior is conditioned by high volatility and dissolubility that results in the accumulation of the main mass of the agent that is discharged into an ecosystem from the waters of warmer climates. TABLE 4 The concentration of chlorinated hydrocarbons in neuston. Chlorinated Hydrocarbon Concentration (ng/g dry weight) PCB 3.5 3.7 2.5 2.3 2.5 2.6 2.8 2.3 3.1 4.1 3.7 3.5 3.8 3.5 1.9 3.5 6.5 7.1 5.1 7.1 3.3 3.5 2.8 3.6 5.5 4.3 6.0 3.3 3.4 3.9 3.5 3.3 4.3 4.6 5.9 4.8 4.9 4.8 Station pp"-DDE pp-DDD pp--DC 2 1.0 0.5 1.1 3 1.0 0.4 1.1 5 0.9 0.2 1.0 4 0.8 0.2 0.8 5 0.9 0.2 1.0 6 0.9 0.6 1.0 7 1.0 0.6 0.9 9 0.9 0.3 1.0 11 1.0 0.5 1.0 13 0.9 0.3 1.0 15 1.3 0.7 1.5 18 1.3 0.7 1.3 19 1.2 0.6 1.2 22 1.3 0.6 1.4 24 0.6 0.2 0.7 32 1.0 0.4 1.3 35 0.9 0.7 0.4 36 1.8 0.9 4.5 41 2.0 1.5 2.6 45 2.1 1.0 2.7 47 1.6 1.2 1.9 49 1.8 1.0 2.1 50 1.0 0.4 1.5 52 1.8 1.2 1.7 53 1.9 1.2 1.8 55 1.5 1.0 1.3 59 2.4 1.1 2.4 61 1.5 1.0 1.3 64 1.4 0.9 1.2 74 1.2 1.0 1.1 82 0.9 1.0 1.0 86 0.5 0.5 0.7 89 1.5 1.0 1.9 96 1.5 0.8 1.9 104 ") ") 1.0 2.5 106 1.9 0.6 2 2 109 1.4 0.9 1.8 111 1.4 1.0 1.8 TABLE 5 The concentration of chlorinated hydrocarbons in plankton. Chlorinated Hydrocarbon Concentration (ng/g of dry weight) Station p.p'-DDE p.p'-DDD p.p-DDT PCB 1 -I 3 4 5 6 7 9 11 13 15 18 24 27 32 35 36 41 45 47 49 50 52 53 55 57 59 61 64 67 69 72 74 82 86 92 111 1.2 1.1 0.5 1.1 0.9 0.9 0.6 0.6 0.8 1.2 1.2 1.3 1.4 1.8 0.8 1.9 1.5 1.2 1.5 0.8 1.0 1.0 2.0 1.3 I.I I.I 2 2 0.5 0.5 1.0 0.4 1.3 1.2 1.3 0.7 0.9 1.5 1.2 1.1 0.2 0.4 0.3 0.2 0.2 0.2 0.2 0.4 0.6 0.6 1.4 1.6 0.2 1.6 1.5 1.2 1.0 0.2 0.4 0.8 0.8 0.6 1.2 1.0 1.0 0.6 0.4 0.6 0.2 1.2 1.2 0.8 0.5 0.2 0.8 1.3 3.4 1.1 2.9 0.8 1.9 0.9 3.7 1.0 1.8 0.9 1.8 0.8 1.5 0.7 1.7 0.7 3.2 0.9 2.9 1.1 2.5 1.2 3.9 1.5 5.7 1.7 5.5 0.8 2.3 1.9 6.1 2.0 6.6 1.4 6.2 3.1 6.2 0.8 6.3 0.8 2.7 1.0 3.0 0.8 4.4 1.2 3.3 1.2 4.2 1.2 3.7 1.5 5.5 0.6 2.8 0.6 3.0 0.6 2.9 0.9 1.5 1.2 4.8 1.2 4.0 1.2 3.2 0.9 2.8 2.0 3.4 1.2 3.9 283 TABLK 6 The concentration of chlorinated hydrocarbons in benthic organisms (soft tissues). Concentration (ng/g of dry weight) Station Objects DDE DDD DDT PCB 12 69 13 19 27 35 45 50 65 47 55 52 53 52 53- 50 72 102 47 55 59 61 13 36 45 64 67 72 13 24 52 Phaeophyta Laminaria (seaweed) Anthazoa. Nephydae Eunephtya tiibifoniiis (corals) Actinoidea Actinia sp. Bivalvia Nucidana sp. Gflldia hyperborea EUiptica etliptica Gastropoda Margariles sp. Gastropoda Nudibranchia Crustacea Ainphipoda Slei^ocephalus sp. Ampilisca sp. Decapoda Chinocetis opiiio (crab) Piii>iinis sp. (hermit crab) 10 4 10 7 12 12 20 15 21 7 4 10 7 X 3 4 5 16 15 68 67 18 1 11 1 26 1 114 95 15 10 11 83 16 11 10 98 6 7 4 43 11 12 14 58 20 10 11 93 8 4 4 85 6 5 9 85 7 8 4 23 13 5 10 82 9 10 6 33 2 T 1 29 3 3 T 29 12 9 44 57 11 15 14 87 3 99 6 73 5 71 5 54 73 40 29 66 43 59 82 55 51 TABLE 6 - continued Concentration (ng/g of dry weight) Station Objects DDE DDD DDT PCB Pagunis sp. (hermit crab) OJ - - 55 .". 65 ?» 72 male -'"- 72 female -"- 96 _"_ 102 89 crab -"- 92 crab -"- Crustacea Pundalidae 92 96 _"_ Crangonidae 66 -"- Sclerocrcmgon sp 36 41 -■■- Shrimps 7 -'■- 45 72 _"_ 86 45 47 55 21 13 14 92 11 9 9 74 12 10 11 93 20 10 11 94 2 2 1 75 9 5 3 53 12 9 17 68 20 12 10 82 20 15 10 91 14 12 11 76 8 8 3 63 10 34 Gorgoi'ocephalus sp. 10 Echinoidea Sea Hedgehog Holothuroidea Mxriolriichiis rinkii 52 Hololhuria Bryozoa 21 Sea-mosses 102 -'■- 105 Tunicata 41 -"■- 96 B (ihvnia ovifcni 10 13 67 22 12 11 103 0 3 5 39 10 6 13 46 15 17 13 74 7 -> 1 21 Echinodermata Asteroidea 2 Cleiiodisciis crisraliix (star) 3 3 T 15 7 23 18 17 71 Ophiuroidea 7 Ophiura sarsi 28 23 14 54 19 -"- 12 10 13 73 35 -"- 21 12 15 62 64 .". 5 6 5 25 69 _"_ 5 3 3 21 18 Ophiura sp. 4 3 4 53 45 -"- 5 6 3 42 44 67 24 10 7 74 T 1 1 12 24 10 7 74 10 8 19 64 19 21 12 45 -> 3 8 99 2 2 7 29 8 12 15 73 4 5 3 27 284 8.1.3 Organochlorine Contamination of Sediments, Fish, and Invertebrates CLIFFORD P. RICE\ ALEXANDER J. KRYNITSKY*, and PASQUALE F. ROSCIGNO* ''Patuxent Wildlife Research Center, US Fish and Wildlife Service. Laurel. Maryland. USA *US EPA, Analytical Chemistry Laboratory. Beltsville. Maryland. USA *National Wetlands Research Center. US Fish and Wildlife Service. Slidell. Louisiana. USA Introduction Organochlorine (OC) contamination in the Bering Sea and Chukchi Sea ecosystems is relatively unstudied. Some data are available on walrus (Odobenus rosmarus divergens) from Little Diomede (Taylor et ai. 1989), and some fish, seals (.Leptonychotos weddelli), and lower food chain organisms from the southern Bering Sea Tanabe & Tasukawa, 1980; Kawanoe/fl/., 1986;Kawanofrfl/., 1988),butnocomprehensive study of OC"s in the northern Bering Sea and Chukchi Sea ecosystems has been attempted. The present account fills this data gap and was made possible through the Third Joint US- USSR Bering & Chukchi Seas Expedition aboard the research vessel (RfW) Akademik Korolev. Atmospheric sampling in other regions of the Arctic suggested that hexachlorocyclohexanes (HCH's), polychlorinated biphenyls (PCB's). hexachlorobenzenes (HCB ■ s ), and toxaphene might be found in the food webs of the Bering and Chukchi Seas (Bidleman era/., 1989; Pattone/rt/., 1989). Toxaphene was of special interest as few reports exist for this purported global contaminant despite evidence since 1978 that it occurs in biota in remote pristine environments (Zell & Ballschmitter, 1980). Materials and Methods Samples All samples were collected from the WW Akademik Korolev while participating on a joint US-USSR expedition to the Bering and Chukchi Seas from 26 July to 2 September 1988. The stations that were occupied are shown on the frontispiece to this volume and the numbering here corresponds to numbering shown in that figure. Zooplankton and phytoplankton were collected by net tows. Surface fihn organisms — neuston — were collected using a special surface trawl described by Zaitsev (Subchapter 5.2.5, this volume). All samples were stored in precleaned 1-Chemjars (I-Chem Research Inc., New Castle, Delaware) after excess water was decanted. Samples were stored frozen (-10°C). A bottom trawl was used to obtain benthic organisms, including shrimp, family Pandalidae; crabs, family Paguridae; molluscs, family Nuculidae; and urchins, family Strongyloccntrotidae. Large samples were placed in plastic Whirl-pak bags and frozen forstorage. Fish (pollack, Theragra chalcogramma; and a sculpin, Cottus sp.) were obtained by hook and line, wrapped in aluminum foil, and kept frozen until analysis. Sediments were obtained using a box corer provided by Texas A&M University. To secure the core samples from this collector, 10-cm core tubes were pushed into the box cored samples so that vertical profiles of the bottom samples could be obtained for later sectioning. Cores containing the sediment samples were capped and frozen in an upright position and were kept frozen until they were sectioned. Additional bulk samples were also taken from the box core collections. Nearsurface, 0-2 -cm layers were scraped off and placed directly in I-Chem jars. Deeper cuts, 0- 10-cm layers were collected using a stainless steel spoon. These samples (4-8 kg) were placed in 1-gal polyethylene jars, thoroughly mixed and subsampled in 1 00-200 g portions for OC and metals analyses. All collected sediment samples were kept frozen until preparation for gas chromatography (GO analysis. Analysis All samples were analyzed for organochlorines by electron capture gas chromatography; selected samples were analyzed for toxaphene using negative chemical ion GC mass spectrometry (GC/MS). Biota samples were homogenized whole without any separation of soft tissues from shells and exoskeletons, mixed with ignited Na2S04 (150 g to 10 g wet biota sample), dried overnight in a desiccator, then Soxhlet-extracted for 7 h using pesticide grade hexane. Biota extracts were split into two equal portions; one was dried and weighed for lipid determinations, the other was processed further prior to GC analysis. The sediment samples ( 20 g of slightly moist material ) were extracted by Soxhlet using a 50:50 mixture of pesticide grade acetone and hexane. To remove the water and acetone from the extracts, they were alternately washed with water and then hexane. The final hexane extract was dried by passing it through a column of ignited Na^SOj. The entire soil extract was processed for GC analysis. For initial removal of fats and other interfering materials from the extracts, we used the florisil column cleanup method ofCromartieandassociates(Cromartiee/a/., 1975). Silica gel column chromatography was used to separate PCB's in the extracts from the majority of OC pesticides (Cromartie et ai, 1975; Kaiser era/., 1980). For removal ofphthalates and traces 285 of fats, sulfuric acid was used as the final step of cleanup just prior to injection of the samples into the GC (Patton et al., 1989). The florisil and silica gel absorbent materials had to be extensively cleaned prior to use in order to reduce their blank contributions to acceptable levels. These cleanup steps involved ignition of the florisil overnight in a muffle furnace at 600°C and batch extraction by Soxhlet of the silica gel with pesticide grade petroleum ether. Extracts were analyzed by electron capture detection using a Hewlett-Packard model 5890 GC equipped with an autosampler. All data were processed using Nelson chromatography software. The GC separation was completed on a J&W DB-1701 (J&W Scientific, Folsom, California) megabore fused silica capillary column, 30 m x 0.53 mm ID. The carrier gas was H, at a flow rate of 20 ml/min. The heated zones were 250°C for the injector and 325°C for the detector. The GC program was as follows: 120°C hold for 1 min; increase to 160°C at 20°C/min; then programmed at 2°C/min up to 225°C; and finally held for 5 min. Quantitation was performed using the external standard method. Standard peak area integration was used for all single component pesticides; however, peak heights were used for PCB quantitation. The heights were summed for all peaks that matched the retention limes of Aroclor 1242, Aroclor 1254. or Aroclor 1260. Each extract collected from a silica gel fraction was prepared for injection into the GC by volume reduction to about 1 ml via a Kudema Danish concentrator assembly, shaking with 1 ml of concentrated sulfuric acid for 30 s, and reduction of the acid-treated extract to 0.5 ml by blowdown with N, gas. With the sediment extracts, it was necessary to add 2-3 drops of elemental mercury to each 0.5 ml of final extract, and mix it until all elemental sulfur was removed. Samples selected for toxaphene analysis were not treated with sulfuric acid in order to preserve structural integrity of the toxaphene components. Also, the fractionated silica gel extracts were recombined to allow for maximum recovery of any toxaphene that might have partially split into separate fractions. In preparation for injection these extracts were reduced by N, blowdown to 0.2 ml and injected into the Varian GC attached to a Finnigan TSQ-70 mass spectrometer operated in the negative chemical ionization mode. The mass spectrometer was set up according to the procedures of Swackhammer and associates (Swackhammer ef a/. , 1 987 ) except for modifications to the choice of the GC column (DB-1, 30 x 0.32 mm ID— 1 |i film thickness), minor changes to the GC operating conditions, and use of the external standard method for quantitation. For qualitative verification of toxaphene in the samples, the retention times of the peaks of each of the characteristic mass chromatograms were compared to similar chromatograms of the standards. The capillary column was able to resolve 68 peaks in the standard. The quantitation routine in this method allows for both retention-time-matched and nonretention-time-matched peaks to be included if they are present in the appropriate mass ranges; therefore, there was always plenty of integrated area above the blank levels to be used in the quantitations. Because of the selectivity of this program for identifying only toxaphene peaks, the toxaphene results should be considered very reliable. Procedural blanks were carried through each analytical step to correct for background interterences from reagent contamination and handling. Samples were processed in batches of 10 to 20, with at least one matrix spike, duplicate, and blank to monitor the accuracy and precision of the analysis for each batch. To report a residue as detectable, the raw number had to be at least twice the blank. Recoveries were monitored by carrying out matrix spikes with mixtures of the expected pesticides and Aroclor mixtures. The levels for spiking ranged from 2.5 to 12.5 ng/g for the organochlorine pesticides and 12.5 to 125 ng/g for the PCB's. For the biota the average recoveries were as follows; Total PCB— 49%; p,p'-DDE [2,2-Bis(p-chlorophenyl)- 1, 1-dichloroethylene]— 86%; HCB— 73%; alpha-HCH— 95%; gamma-HCH — 81%';oxychlordane — 77%;trans-chlordane — 88%; cis-chlordane— 88.6%; trans-nonachlor— 78%; p,p'-DDD [2,2-Bis(p-chlorophenyl)-l,I-dichloroethane] — 88.4%; cis-nonachlor— 76%; and p,p'-DDT [2,2-Bis(p-chlorophenyl)- 1,1,1 -trichloroethane] — 65%. For the sediment, the recoveries were all low but consistent as follows: Total PCB— 39%; p,p'-DDE— 57%; HCB— +6%; alpha-HCH — 45%; gamma-HCH — 44%; oxychlordane— 44%; trans-chlordane — 40%; cis-chlordane — 42%; trans-nonachlor — 41%; p,p'-DDD — 55%; cis-nonachlor — 42%; and p,p"-DDT— 36%. Duplicate results were collected for each batch of 20 or less samples. Generally there was good agreement between the two values, with the relative percent differences averaging less than 25%. Both electron impact and negative chemical ionization mass spectrometry were employed to confirm the residues identified by electron capture GC. In some cases, residues were identified even though they were below the detection limits of the electron capture methods. Results and Discussion Organochlorine residues were present in all of the samples analyzed (Tables 1,2,3). The highest single component OC measured was the HCH class of compounds, especially alpha-HCH at 8. 1 2 ng/g in one of the bivalve samples. In the mixed OC component classes of compounds, PCB's and toxaphene comprised the highest residues. For example, in neuston there was 67.9 ng/g total PCB's (Station 22); in zooplankton 23.9 ng/g total PCB's (Station 11 3, Table l);and in pollack 10.8 ng/g toxaphene (Station 4, Table 3). Of the single-component organochlorine pesticides other than HCH' s, HCB was relatively high in some of the crabs and bivalves, and trans-nonachlor and p,p'-DDD were generally high in fish, zooplankton. and phytoplankton. The sediment was notably devoid of most of the OC's found in biota (Table 2). Alpha-HCH was found in a few sediment samples, detectable levels of DDT and PCB's were measured in sediment surface layer (Station 45), and some chlordane peaks were evident in the deeperhomogenized sample (Station 13). Our data suggests that sediments are not reservoirs supplying organochlorines to the biota but rather acting as sinks. Further, it appears that the atmosphere is the major loading factor in this system. 286 TABLE 1 Organochlorine concentrations (ng/g fresh wt.) in biota from the Bering and Chukchi Seas. Sample Type Sta. % PCB- PCB^ PCB- Total HCB a-HCH Y-HCH 13-HCH OXY trans- cis- trans- cis- DDE DDD DDT No. lipid 1242 1254 1260 PCS CHL CHL NON NON Hermil Crab 5 2.hS 10,99 <3.07 <2,37 13.71 0.93 1,54 0,34 0.63 <0.19 <0.20 0,31 0,45 <0.19 0,43 <0.18 3,48 Hermit Crab 13 1.89 <5,56 <3.03 <2.33 <10.92 2.90 1.84 0,32 0.93 <0.19 <0.20 0.24 0.49 <0.19 0.44 <0.I8 <0.19 Hermit Crab 53 1,74 <6,62 <3.06 <2.36 <11.04 <0.45 1.80 0.33 1.57 0.21 <0.20 <0.17 0.20 <0.19 <0.38 <0.18 0.27 Hermit Crab 11)0 148 <5.84 <3.18 <2.45 2.0) more typical of an oil signature (see the discussion below). Gas Chronuitof^raphy Gas chromatographic analysis demonstrated that aliphatic hydrocarbons are ubiquitous in sediment extracts throughout the survey area. Normal alkanes were predominantly of terrestrial, biological origin as evidenced by the abundance of compounds with 23, 25, 27, 29, and 31 carbons (Fig. 5). The lower molecular weight alkanes were only a small percentage of the total n-alkanes in most cases. In general, most alkanes appeared to be of a biological origin, including complex mixtures of normal and branched alkanes and alkenes with 15, 17, and 21 carbons. The presence of petroleum related n- alkanes and/or UCM"s were observed in sediment extracts at Stations 22. 32, 33, 45, 67, 92, and 107. In gravity cores the highest concentrations were deep in the core suggesting an upward migration source. A low level unresolved complex mixture was observed at many locations. The geographic distribution of the total unresolved complex mixture is presented in Fig. 6. The co-occurrence of high fluorescence and R ratio values and GC derived indicators confirms the presence of microseepage at several locations. 294 Majdjnum Fluorescence Intensity Fluorescence Ratio (RI ) Wavelength (\) Fig. 2 . Summary of fluorescence analysisofsedimentextraclslrom the study area. Polynuclear Aromatic Hydrocarbons (PAH's) Quantitative PAH deteiminations revealed that low levels of PAH were detected throughout the study area. Generally total PAH concentrations were less than 100 ppb (Fig. 7). The highest PAH levels were detected in the deeper sections of gravity cores (averages for all samples at a site were used to produce regional maps)(Fig. 8). In general, relative regional anomalies in fluorescence intensity. UCM, and PAH coincide. Background PAH's, composed primarily of nonalkylated analogues, have been ascribed to pyrogenic sources ( Kennicutt & Comet, 1990). Thisisconsistent with much of the low level PAH and fluorescence intensities reported here. Polynuclear aromatic hydrocarbons compositions at locations with total PAH in excess of 100 ppb are more indicative of natural seepage. Macroseepage has been documented to the south and southwest of the present study area. Both oil and condensate seepage was detected and their general locations are consistent with the regional variations observed in the present study (Kennicutt et ai. 1990). Biomarkcr Analysis The previous reports of significant amounts of unique biologically-derived aliphatic hydrocarbons in the eastern Bering Sea was confirmed. Many of the sediment extracts contain compounds previously identified as olefins. A tetraene (Kovats Index |KI] = 2657). squalene (KI = 2895), and aC30 bicyclic tetraene (KI = 3027) are believed to be due to inputs from zooplankton and/or phytoplankton. These compounds were detected at most locations though concentrations varied widely. A suite of hopenes, moretanes, and pp-hopanes were present at several locations and appear to represent a recent background biological marker mixture. This background may represent erosionally exposed, in place, sediments or materials from the surrounding land masses that have been transported to the site of deposition (i.e., recycled). The precursor functionalized hopanoids and steroids representative of unaltered biolipids were not determined by the analytical methods utilized in this study. The hopanoid compounds most likely represent early alteration products of biogenic lipids of bacterial and/or algal origin. In contrast to these immature markers, overprinting by 17a, 21 (i hopanes; diasteranes; and steranes (oca and aPP) are evident at sites suspected of containing mature, migrated petroleum (Table 1 ). These mature biomarkers, which are only produced when temperatures are substantially higher than in these near-surface sediments, are present in extracts from a few stations (Table 1 ). These mature petroleum hydrocarbons — derived from a much deeper, higher temperature source — overprint the in situ biological and "recycled" immature lipids. Conclusions Aliphatic and aromatic hydrocarbons were widely detected at locations sampled in the Bering and Chukchi Seas. The hydrocarbons are a mixture of marine biological debris (bacteria, algae, zooplankton, phytoplankton), terrestrial plant biowaxes TABLE 1 Presence (+, ++, +++) or absence (-) of selected mature biomarkers in Bering Sea extracts. Core Triterpanes Steranes Monoaromatic Tiraromatic # (m/z=191) (m/z = 217) Steranes Steranes (m/z = 253) (m/z = 231) 3 + 7 - + 19 22 ++ +++ 32 +++ +++ 45 ++ -1- 47 - ++ 49 - + 50 - - 53 - - 66 - - 74 - - 79 - - 81 - - 92 - - 97 - - 109 - - 110 - + ++ 295 1? ^^^ ► • • • rv^ • • • • V • • • _v_24— • a^^ -"' ^' Fig. 3. Geographic dislribution of sediment extract nuorescence intensity from the study area (contour mdicates the highest 25'7c of the values, >300). (normal alkanes), "recycled" orexpo.sed immature sediments, petroleum (natural seepage ), andpyrolytic sources. The relative amounts and composition of hydrocarbons varied widely over the area sampled. The presence of a complete suite of normal alkanes and isoprenoids, an unresolved complex mixture, petroleum related PAH"s, mature biological markers (hopanes and steranes), and vertical distributions of hydrocarbons in cores confirm the presence of petroleum related hydrocarbons at several locations. This petroleum is most likely derived from natural seepage from much deeper source rocks and/or reservoired tluids. Significant geographic variations were noted in all parameters measured and definable regional highs were apparent. The coincidence of fluorescence and GC derived petroleum indicators provides confimiatory information on the presence of mature petroleum hydrocarbons at several locations. These regional highs were lower than previously reported macroseepage to the south and southwest survey. When present, mature biological marker distributions were similar in general, suggesting acommon source forthe migrated hydrocarbons. 296 '"■"^--i«r« Fig. 4. Geographic distnbution of sediment extract fluorescence ratios from the study area (contour indicates the highest 25% of the values. >0.21). 297 Average Alkane Concentration (ppb) n-C15 Fig. 5. SuniniLiry of the average n-alkane distnhulion and ccmcenlration fur all sites sampled. 298 Fig. 6. Geographic distribution of sediment extract unresolved complex mixture (UCM) concentrations by GC/FID from the study area. 299 Total PAH Fig. 7 Summary of sediment extract total polynuclear aromatic hydrocarhon (PAH I concentrations from the study area. Fig. X, Geographic distribution of sediment extract (PAH I concentrations for the study area (contour indicates the highest 2?% of the values, >65 ppb). 300 8.2.2 Distribution of PAH's NATALYA I. IRHA, EHA R. URBAS, and UVE E. KIRSO Institute of Chemistry, Estonian Academy of Sciences, Tallinn, USSR Introduction Among the more than 50,000 known pollutants in the hydrosphere, the carcinogenic polycyclic aromatic hydrocarbons (PAH" s) are detected in almost all compartments of marine ecosystems. The pathways for the movement of PAH's into seawater is still a subject of much discussion by the scientific community. Human activities (Kirso et al.. 1988) and natural processes (Lisitsyn, 1989) are considered two likeliest routes. A large amount of data has been obtained on the regularities of the distribution of a typical carcinogenic PAH — benzo(a)pyrene (BaP) — in the marine environment. In order to describe the modem distribution of PAH's, one must consider historical changes in man's culture (Izrael &Tsyban, 1985a). Due to their high hydrophobicity and low solubility, the investigation of PAH's in contact zones of the ocean (Vinogradov, 1990) (i.e., at the sediment-water and air-water interfaces, where so-called zones of 'condensed life' have been observed) are of interest (Fig. 1 ). Si jnlighl photolysis Air Assimilalion ^-"'^N.. b> living organ 1 Sims entrance into the food chain Accumulation and transmission of migrating biota / / Living matter f u — sorption BiosedimeniaKo t — Water layer thickness Fig. 1 . Scheme of natural agents contributing to the transformation of PAH in marine ecosystems. To obtain further information on the characteristics of the spatial and temporal variations in PAH pollution, a complex study of PAH concentration in the ecosystem of the Bering and Chukchi Seas (specifically the suspended matter, bottom sediments, and biota) during the cruise of the R/V Akademik Korolev was undertaken (47th cruise, July-November 1988). Sampling, Processing, and Analysis of Samples Sampling Preparation and analysis of samples of water, bottom sediments, plankton, benthos, and hydrobionts were carried out using standard methods (Tsyban et al., 1988). All the solvents used were preliminarily purified by passing them through activated carbon. To take samples from the surface microlayer (SML), a metal screen (cells 2x2 mm) was pulled horizontally across the sea surface. Samples from the other horizons were taken using a standard water sampler. The bottom sediments were taken with a dredge. These samples were dried at 50-60°C and stored in polyethylene bags. Suspended matter samples were taken from different horizons by means of a 'Midia' pump equipped with filters 0.5 |a m in pore diameter. The filters were previously purified with hexane. The filters with suspended matter were dried at room temperature and stored in polyethylene bags. Plankton and neuston samples were collected with plankton nets, and benthos were collected with a bottom trawl. Plankton and neuston samples were collected on filter paper and dried on foil in a drying oven. Extraction Water ( 2.5-5.0 1 ) was twice extracted with hexane ( 1 00 ml each) with a magnetic stirrer for 2 h. The combined extracts were dewatered with sodium sulphate, evaporated to 0. 1 ml and dried at room temperature. Bottom sediment samples (10.0 g) were extracted with 50 ml benzene under static conditions at room temperature in the dark for 48 h. The solids were removed and the extract was evaporated to 1-2 ml. Air- dried samples of plankton, neuston, and benthos tissues were saponified with a 92% ethanol-KOH mixture (25 ml of ethanol and 1 g of KOH per g of sample) at 45°C in a water bath for 48 h. The hydrolysate was extracted with hexane ( 10 ml each); the extract was concentrated and dried. Chromatographic fractionation of the extracts was carried out using thin layer chromatography plates, which were coated with aluminum oxide . The solvents for developing the plates were chosen as follows: (a) for separation of total PAH fractions, used a benzene:acetone mixture (9:1). (b) for separation of BaP, used a mixture of petroleum ether (fraction 40-70°) and chloroform (9: 1 ). The zones containing the PAH's on the plate was marked using fluorescence UV-irradiation (A^^^ ~ 360 nm). For identifying BaP, a BaP standard was used (a BaP solution in benzene, concentration 5 x 10"^ g/ml). The zone containing PAH's was collected and washed off with a 1:1 mixture of benzene:acetone. The extract was evaporated and 301 dried at room temperature. A quantitative determination of BaP was performed using the spectral-luminescence methods based on the measurement of the relative intensity of the luminescence of the BaP solution in n-octane and using benzo(ghi)perylene (BPer) as an internal standard, which was frozen at -196°C, (Shpolshy effect- [Fedoseyeva and Khesina, 1968]). A quantitative determination of the other PAH's was carried out using high-performance liquid chromatography ( HPLC). A mixture of PAH" s similar in composition to known environmental pollutants served as standards [US NIST Standard Reference Material, SRM-1647a|. The determination of the PAH"s was carried out starting with pyrene. which was the first to elute from the column. Conditions of Analysis Dry samples were dissolved in 0.2 ml of acetonitrile and introduced into a "Knauer" liquid chromatograph equipped with a 'Kratos' fluorescence detector. The excitation and emissions wavelengths were 295 nm and 418 nm; the eluent solution was 95% methanol in water at a flow-rate of 0.5 ml/min through a (25 x 0.25-cm) 'Perkin Elmer' Sil ODS column. The absolute calibration method was used for the determination. The sensitivity was 10'' g. Results and Discussion In the water, sediments, suspended matter, and biota of the Bering and Chukchi Seas, 10 PAH's were identified, of which eight are carcinogenic and three of these (viz., benzo(b)fluoranthene [BbF|, benzo(k)fluoranthene [BkF] and BaP) are highly carcinogenic (Table 1). PAH's in Water In the Bering Sea and the Bering Strait, the PAH concentration in water was below the sensitivity of the HPLC method. In the northwestern Bering Sea and eastward from St. Lawrence Island, the surface and near-bottom water contained a high concentration of PAH's (from 0.5 to 149.2 ng/1) which were made up of seven representatives of four- and five-nucleated PAH's (Table 2). In the surface layer the following compounds prevailed (wt. %): benzo(e)pyrene [BeP] 40.3, pyrene [P] 35.14; the concentration of other PAH's was as follows: BbF, 17.6: BaP, 4.76; and BkF, 2.2%. In the near-bottom layer, the distribution of PAH's was the following: BeP, 47.43: benz(a)anthracene [BaA] and chrysene [Chr], 40.4; Py, 7.67; BbF, 2.7; BaP, 1.9: and BkF, 0.2. Thus, the concentration of PAH's in surface and near- bottom layers differed. In the water of the central, southern, and partly northeastern areas of the Bering Sea and the Bering Strait, insignificant amounts of BaP were detected (Table 3), not exceeding the background level. In most cases, the PAH concentration in the surt'ace water layer was twice as high as that in the near-bottom layer. While in the central part of the Bering Sea (Fig. 2), the BaP concentration increased 10-fold from the top to the bottom (e.g.. Station 6 increased from 0.1 ng/1 at the surface to 1.02 ng/1 in the deepest sample). Table 1 List ol specific PAH's identified by displacement-elutional liquid chromatography Name Symbol Structural formula Carcinogenicity (Lee«u/, \VH\) Pyrene Chrysene Ben/(a)anlhracene Bcn/otelpyrene Ben/oihlfluoranthenc oS^ BaA BbF oc6^ Benzolkitluoranthene BkF Benzotalpyrene BaP Benzotg.h.ilperylene BPer Dibenzta.hlanthraccnc DBA Indeno(l,2,.^-cd)pyrene IPy Note Classification noncarcinogenic weakly carcinogenic strongly carcinogenic Symbol 0 Criterion: % of animals that developed lesions 0 33 >33 According to our data the total concentration of PAH's in the SML in that same area was also below the sensitivity of HPLC, but the concentration of BaP ( Fig. 3 ) is x3 as high as that in the surface layer; however, they did not exceed the values established for SML in the other oceanic environments (Anikejev&Urbanovitch, 1989). The concentration of PAH's in the Chukchi Sea waters was also often below the sensitivity of HPLC method. In the water of the southeastern part of this sea, the same 4- to 5-nucleated PAH's were identified as in the Bering Sea (Table 2): Py, BaA, Chr, BeP. BkF, BaP. Their overall concentration in the surface water layers did not exceed 5. 1 ng/1, but in the near-bottom layer it reached 24 ng/1, which is considerably lower than the respective values for the Bering Sea. Five-nucleated PAH" s accounted for the major portion of the total concentration of PAH in the surface layer ( wt % ): BeP, 72; BbF, 28. Benzo(a)pyrene, BaA, and Chr were present in trace amounts and the near-bottom layer was characterized by the following pattern: BeP, BbF, and BaP which accounted for 72, 23, and 5%, respectively. Benzo(a)anthracene and BkF were present in trace amounts. The abundance of BaP in the surt'ace water layers in the Chukchi Sea area, where the level of PAH was below the sensitivity of HPLC. was also insignificant being lower than for the Bering Sea (Table 3). However, in the near-bottom layers of both seas, its level was the same. It should be mentioned that the concentration of BaP in ice samples was somewhat higher than in the surface water layers (Fig. 4) and it increased with depth. 302 TABLE 2 PAH Loncentration (ng/1) in the Bering ( I ) and Chukchi (2) Sea waters (47th cruise of the RA' Akadeinik Korolev. July-November 1988). Indices Py BaA+ Chr BeP BkF BbF BaP surface layer (0-0.5 m) n* 2 - 5 1 3 1 3 1 4 1 6 15 minimum 3.4 - traces - 3.8 - 0.1 traces 0.1 - 0.07 0.01 ma.ximum 4.1 - q' q 5.2 3.3 0.5 - 6.4 1.8 1.6 0.5 average 3.8 - - - 4.3 - 0.2 - 1.9 - 0.5 0.2 standard deviation 0.5 - - - 0.8 - 0.2 - 3.0 - 0.5 0.2 near-bottom layer n* 3 T ■> 1 4 2 5 3 7 3 7 13 minmium 1.6 q 4.7 q 2.3 2.0 0.02 traces 0.2 1.2 0.2 0.01 maximum 7.0 15.0 56.0 3.7 88.4 10.0 0.3 0.1 4.3 3.2 2.4 0.6 average 4.5 - 30.3 - 28.0 6.2 0.1 - 1.6 2.3 0.8 0.2 standard deviation 2.72 - 36.3 - 40.6 5.3 0.1 - 1.4 1.0 0.8 0.2 n* - number of points q* - qualitative TABLE 3 Concentration of BaP (ng/1) in suriace ( 1 ) and boundary bottom (2) water layers of the Bering Sea, the Bering Strait and the Chukchi Sea (August 1988). Object Number of Points Limits Average ± standard dev. Number of Points Limits Average ± standard dev. Bering Sea Bering Strait Chukchi Sea 19 4 15 up to 0.78 0.14-1.60 up to 0.51 0.32 ± 0.24 0.57 ± 0.69 0.20 ±0.19 12 4 13 up to 0.74 0.10-0.31 up to 0.63 0.19 ±0.20 0.23 ±0.12 0.20 ±0.1 7 303 60° 55° 50° 165° 170° 175° 180° 175° 170° 165° Fig. 2. BaP concentration (ng/1) in the Bering Sea waters depending on depth (m). Station 3: (1 ) 0-0.5; (2) 45; (3) 100; (4| near the bottom layer. Station 6:, (1)0-0.5; (2) 10;(3)45;(4) 100. Station 18: , (1) 0-0.5; (2) 45; (3) 70. 1.0 r S 0.5 c o u CQ 0.1 0 0.65 Li 0.18 - surface micro layer H - surface layer 0.16 0.06 -:- 1.0 00 c c 1) 0.63 c o o 0.51 Oh CQ 0.16 r\ 0 ice 0±0.5 m 16 m 48.0 m bottom boundary layer Fig. 3. BaP concentration (ng/1) in surface microlayer and surface water Fig. 4. BaP concentration (ng/1) in ice and water samples from different samples in rhe Bering Sea (a = Station 1 10. b = Station 24). horizons of the Chukchi Sea (Station 15). 304 PAH's in Suspension It is known that PAH's, being of poor water solubility, are readily sorbed onto suspended particulate matter, accumulated in bottom sediments and are sorbed by biota (Fig. 1 ). In the Bering Sea and the Bering Strait, five suspended matter samples werecollectedatdepthsof 70and 170 m. The total concentration of PAH's in the suspended matter of the surface layer reached 1,620 ng/g, but in deeper horizons the maximum was only up to 1,018 ng/g (Station 110). In the samples at the surface in the Bering Sea the following 4-6-nucleated PAH's (Table 4) were identified (wt %): BaA plus Chr, 19.8; Py, 44.8; BeP, 22.0; BbF, 14.8; BaP, 12.8; and BkF, 2.5. It should be noted that the weight composition of PAH's in these suspended sediment samples varied within a wide range depending on the regions sampled; for example, at some locations the concentration of BbF reached 48%, that of BaA plus Chr, 42%, and BeP, 22%. At the same time, at deeper horizons, BeP concentration increased up to 78% of the total PAH's concentration and, correspondingly, the percent composition of the above PAH's decreased. The BaP concentration in the suspended matter never exceeded 1 5% of total PAH concentration. In the Chukchi Sea the concentration of total PAH's in suspended matter in the upper horizons. Station 45, was 3,544 ng/g, and at 40 m it was 89.0 ng/g. The PAH's in the suspended matter samples at the surface from the western part of this sea contained the same 4- to 6-nucleated PAH' s as were identified in the Bering Sea (Table 2) (wt %): BaA plus Chr, 16.4; BkF, 1.6; BaP, 2.2; BeP, 8.5; BbF, 0.33; and P was qualitatively identified. However, among the PAH's, dibenz(a)anthracene |DBA] prevailed, whose concentration reached 7 1 %. In the surface layer, BaA and Chr predominated, their concentration reaching 69% of the total PAH concentration, that of BbF was 20%. At deeper horizons, as a rule — BbF and BaP in the suspended matter averaged 30% of the total PAH's. Thus, the suspended matter of the Bering and Chukchi Seas contained a wide range of 4-6-nucleated PAH's. The composition and ratio of PAH's differed depending on depth and sampling area. PAH's in Biota The concentration of PAH's in the biota, as in the other elements of the ecosystem of the Bering and Chukchi Seas, is low, generally below the sensitivity of HPLC. The BaP TABLE 4 PAH content in the suspension ( ne/g I of the Bering ( 1 ) and Chukchi ( 2 ) Seas (47th cruise of the R/V Akadeinik Korolev. July-November 1988). Py BaA+ Chr BPer BkF BbF BaP BeP DBA Indices 1 2 1 2 1 2 1 2 1 -) 1 T 1 2 1 2 Om n* 3 1 3 1 3 - 3 1 3 1 3 1 3 1 1 minimum iljoo - tr. - - 6.0 - 19.8 - tr. - - - - maximum - 59.4 - 57.4 - 41.0 - 204 - 124 - 495 - - average 337 q* 19.8 581 19.1 - 19.0 5.8 111 8.1 80.8 79.1 165 302 - 2560 standard deviation 583 - 34.3 - 33.1 - 19.0 - 92.2 70.0 0.09 - - - - 1.5 40. 70 m n* 1 . 1 _ - - - 1 1 1 1 - - 1 minimum - - - - - - - - - - - - - maximum - - - - - - - - - - - - 1.6 average q* - q* - - - - 149 89.0 104 tr. - 896 - standard deviation - - - - - - - - - - - - - - 170 m n* 1 - - - - 1 - 1 1 - 1 - - minimum - - - - - - - - - - - - - - maximum - - - - - - - - - - - - - - average q* - - - - 18.5 - 259 - 148 - 593 - - standard deviation - - - - - - - - 0.1 - 0.07 0.06 - - n* - number of points q* - qualitative tr. - traces TABLE 5 Concentration of BaP (ng/i) in surface 1 1 ) and boundary bottom (2) water layers of the Bering Sea, the Bering Strait and the Chukchi Sea (August 1988). Object Plankton Zooplankton Neuston Number of min average standard Points max dev. 0.4-10.6 3.0 0.5-8.4 2.2 up to 10.0 2.6 Number of min average standard Points max dev. 2.9 2.4 3.0 10 0.22-12.6 7 0.6-1.9 2.8 2.0 3.9 2.6 .^(15 concentration (Table 5) in the biota of these regions varied depending on where the samples were taken, as did its average concentration; however, they never exceeded 3.0 |ig/kg dry wt. In the plankton and neuston of the Bering and Chukchi Seas seven 4- to 6-nucleated PAH's were detected (Table 6). The total PAH concentration in the plankton of the Bering Seas ranged from 40 to 480. but in the neuston from 26 to 1 14.8 |ig/kg on a dry weight basis. As shown in Table 6, the major PAH's in the plankton of the Bering Sea were 4- to 5-nucleated compounds, ( wt %): Chr, 40; BaA, 24.6; BbF, 22; BaP, 11.8; and BkF, 1.6. Also BPer, lndeno( 123cd)pyrene [IP], and BeP were detected in the phytoneuston of the northwestern part of the Bering Sea. The total PAH concentration in the neuston of the Bering Sea, as a rule, was somewhat lower than in the plankton and varied from 11 to 115 |ag/kg on dry wt. basis. The total concentration of PAH's in the neuston from the northwestern part of the Bering Sea exceeded its concentration in the plankton by a factor of 15-20. However, the composition and ratio of PAH's were nearly identical for both the neuston and theplankton; BaA plus Chr, 41; BbF, 36; BkF, 38; and BaP, 18.2. In the biota of the Chukchi Sea, the composition and distribution of PAH's was somewhat different from those in the Bering Sea. The total concentration of PAH's in the plankton varied widely, viz., from 12 to 677. For the neuston, they ranged from 20 to 1 88 |ig/kg on a dry weight basis. The percent weight of individual PAH's in the plankton samples was 41 for Chr, 26 for BbF, 2 1 .9 for BeP, and 1 . 1 for BaP. In some cases, trace amounts of BPer and IP were detected in plankton, and in one case BeP was detected. In the neuston, PAH's are represented mainly by 4- to 5-nucleated compounds with the distribution ( wt% ) being BbF (37.6%), BaA plus Chr (29%), BaP (25.8%), and BkF (75%). Thus, in the biota of the ecosystem of the Bering and Chukchi Seas. 4- to 5-nucleated carcinogenic PAH's are most common, with Chr, BaA, and BbF predominating (Fig. 5). PAH's in Bottom Sediment The concentration of PAH's in sediment of the Bering Sea varied from 0 to 1.7 |ig/kg on a dry wt. basis. The maximum of 1 .7 ng/kg was detected northwest of St. Lawrence Island (Station 32), which is considerably lower than for the Baltic Sea(Kirsoeffl/., 1985). TABLE 6 PAH concentration in the biota (ng/1) of the Bering ( 1 ) and Chukchi (2) Seas {47th cruise of the RA' Akademik Korolew July-November 1988). Indices BaA/ Chr BPer BkF BbF BaP BeP IP Plankton n* 5/4 -/4 minimum 0.1/2.7 -/l.O maximum 118/189 -/178.0 average 51/83 -/47 standard deviation 57.0/94.0 -/87.0 Neuston n* -) 4 mmimum 15.7 0.01 maximum 32.0 18.0 average 23.8 9.7 standard deviation 11.5 6.9 n* - number of points 71.0 49.0 3 4 6 4 5 4 1 1 1 1 0.1 0.6 1.7 0.5 0.6 0.01 - - 10.0 2.4 116.0 136.0 48.0 91.0 27.0 272.0 80.0 2.9 3.4 1.3 46.0 41.0 24.4 24.7 - - 5.7 0.9 50.0 64.0 31.0 44.2 - - 2 4 -) 4 -) 4 1 1 - 0.8 0.01 5.3 2.9 4.5 0.01 - - 3.7 1.8 35.6 31.8 16.5 7.6 27.0 65.0 - 2.2 2.5 20.4 12.4 10.5 8.4 - - 2.1 3.0 !1.4 11.7 8.5 8.3 Fig. 5. Distribution ol PAH's (wt%l in the biota ol the Bering Strait (Station 83); plankton (a), neuston (b). 306 In sediments in the southwestern parts of the Bering Sea and the Bering Strait, the PAH concentration is primarily below the detection limits of the method. At the same time, seven PAH's were detected near St. Lawrence Island and northeast of there (Table 7). Their total concentration ranged from 0.87 to 4.8 |ig/kg on a dry wt. basis, while BbF accounted for the major part (up to 66.77%). In addition to the PAH's listed in Table 7, low amounts of BaA and IP were detected in the southeastern part of the Bering (up to 10 and 10.48 wt'/r, respectively). The total PAH concentration in the sediment of the Chukchi Sea varied from 8.3 to 76.4 |ig/kg on a dry wt. basis. These values were higher than for the Bering Sea, and BbF accounted for 56.4% of this total. Seven representatives of the 4- to 5-nucleated PAH's were identified. Benzo(a)pyrene was present in nearly all of the sediment samples from the Chukchi Sea. The highest was 4.5 |ig/kg on a dry wt. basis (Station 40) which is about x3 higher than was measured in the sediment samples from the Bering Sea. Publisheddata(Malinsefa/.,1985;Israel&Tsyban, 1987; Kirso et ai, 1988) and those obtained by us show a relatively low level of PAH pollution of water, biota, and sediments in the Bering and Chukchi Seas. Of more concern, however, is the accumulation of the dangerous carcinogen BbF (Fig. 6) which was observed in these ecosystems both in the process of circulation and in biosedimentation. Apparently entering into the marine environment as part of oil pollution, BkF appears to have become concentrated in the neuston, suspended matter, and bottom sediments of these regions. Minor portions also seem to reenter the surface layer. Finally, this carcinogen enters the food chain making it a possible risk to man under the right conditions. (C) (d) Fig, 6. Distributionof PAH's (wt?}-) in compartments of the ecosystem of the Chukchi Sea (Station 74): near bottom layer (a); sediment (b); suspended matter (c); neuston (d). TABLE 7 Concentration (%) of individual compounds of total PAH concentration in the bottom sediments of the Bering Sea. the Bering Strait and the Chukchi Sea. Total PAH Station No. concentration (jig/kg dry wt.) Py BbF BkF BaP BeP BPer DBA 49 3.56 37.35 8.43 54.21 . . . 52 13.20 78.79 21.21 - - - - - 53 3.20 - 56.25 5.62 6.88 - 31.25 64 25.35 22.09 33.14 1.45 0.71 3 1 .56 11.04 - 67 76.40 17.02 31.41 2.62 - 18.06 10.73 - 69 24.83 39.47 56.39 1.03 3.14 - - - 77 3.56 - 50.56 5.06 16.29 - - 28.08 96 0.87 - 41.38 19.54 39.00 - - - 100 1.16 - 45.69 18.96 35.35 - - - 104 4.34 - 43.78 3.22 - 53.00 - 106 4.80 - 66.66 - 33.34 - - - 307 8.2.3 Distribution of Benzo(a)pyrene and other Poly cyclic Aromatic Hydrocarbons YURIY L. VOLODKOVICH and OLGA L. BELYAEVA Institute of Global Climate and Ecology, State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR Introduction In the recent decade, the impact of various social and economic factors on the environment has caused certain negative consequences, including changes in the natural chemical background caused by growing entrainment of pollutants in natural ecosystems. Pollutants, first propagating on the land and in the atmosphere, come by various routes to the world oceans and, in the long run, circulate within them (Izrael & Tsyban, 1989). Coastal regions rapidly accumulate pollutants to critical levels producing irreversible changes in the functioning of marine ecosystems. In open regions of the oceans, aquatic organisms and ecosystems as a whole begin to suffer from a constant impact of low intensity factors such as low doses of toxicants. Among numerous organic pollutants causing dangerous changes in the chemistry and biology of the marine environment, a unique role is played by polycyclic aromatic hydrocarbons (PAH's), including both the natural and anthropogenic-derived materials. With a significant molecular stability as well as pronounced carcinogenic and mutagenic effect, these chemicals present a great danger to the existence of marine organisms. The most characteristic and widely spread chemical of this series is benzo(a)pyrene (BaP), which is widely accepted as an indicator of environmental pollution by carcinogenic PAH"s (Izrael & Tsyban. 1989). Benzo(a)pyrene and PAH's are found in many compartments of sea ecosystems from Arctic (Mallet et al.. 1979) to Antarctic latitudes (Clark e?fl/., 1981). Entrainment of PAH's in the currents of these systems causes their further circulation throughout the seas. One of the consequences of these processes is accumulation of carcinogenic PAH's in traditional marine products; plants and animals sold in commerce (Comer, 1975; Mix et al.. 1983), which ultimately threaten the health of human beings. There are many publications on the distribution of these dangerous chemicals in hydrosystems; however, there is an obvious shortage of systematic information on the patterns and origins of biogeochemical cycles in the ocean ecosystems. This paper considers individual results from investigating biogeochemical cycles in the ecosystems of the Bering and Chukchi Seas. Distribution and accumulation of these toxic chemicals in components of marine ecosystems (in the water, surface layers, sediments, plankton, and neuston) was studied using benzo(a)pyrene as a model compound for explaining PAH processes in general. Considering that the increase in PAH's in a particular marine environment depends greatly on the proximity of the sources of these pollutants, it is noteworthy that there have been recent increases in sources of PAH's in the southeast marginal polar seas. These areas have been noted as only recently being affected by any pollutants at all, which therefore makes it important to study what other pollutants may also be of concern in these regions. Investigations performed in 1988 by the research vessel Akademik Korolev are a continuation of comprehensive work begun in the Bering Sea basin in 1981 and 1984 (Roscigno, 1990). Methods Sampling Polycyclic aromatic hydrocarbons circulation in ecosystem components of the Bering Sea and southern part of the Chukchi Sea, specifically, circulation of benzo(a)pyrene, was studied by the Third Joint US-USSR Bering & Chukchi Seas Expedition on the Akademik Korolev in August 1988. Samples were collected at 54 stations, which include four specific test polygons, the North (Stations 34-37), East (Stations 1-5) and South Polygons (Stations 108-1 12) in these waters. These polygons are sites of continuous sampling, which were visited in 1977, 1981, and 1984 by scienfists from the joint US-USSR expeditions. The goals of the sampling program were as follows; — collect seawater from surface to deep horizons, including a near-bottom horizon; — collect samples of floating ice; — collect bottom sediments (the upper 5 cm of the surface); — collect samples of plankton organisms taken in 45-100 m layers; — collect samples of neuston organisms taken from the top 10 cm of the sea surface; and — continue long-term monitoring at sites occupied previously in 1977. 1981, and 1984. Water was sampled using a Niskin water sampler, 5-101 per sample. Samples were obtained from 5-8 equally spaced horizons from the surface to the sea floor. Surface microlayer water (0.2 mm) was sampled by a stainless steel mesh (0.26 m-) screen. In order to prove that the vessel was not a source of contamination, some of the surface microlayer samples were obtained from a tender boat at a considerable distance 308 from the ship. Benzo(a)pyrene was extracted from 1 1 samples by triple extraction with benzene. Final processing of the benzene extracts (100 ml volumes) were carried out in the laboratory in Moscow. Bottom sediments were collected using an OKEAN dredge, which removed a 0.25 m- area of the bottom without disturbing its stratification. A 5-cm depth was removed from these grab samples (50 to 100 g). These were then dried at 60°C, wrapped in aluminum foil, placed in a plastic bag, and stored for later analysis. Plankton samples were collected using a Gedy net, which was allowed to drift behind the ship at 45- to 70-m depths for 1 h. The collected biomass was dried at 60°C to a constant weight and stored until analyzed at the laboratory in Moscow. Samples of neuston organisms were obtained using a surface neuston net "nHC-2" (see Subchapter 5.2.5, this volume). The samples were dried and prepared for subsequent analysis as described above. Chemical Analysis Quantitative Determination of Benzo(a)pyrene in Seawater The benzene extracts of the samples that contained the benzo(a)pyrene (BaP) were concentrated to 1 ml volumes and chromatographed using thin layer chromatography using alumina coated plates. The running solvent was heptane:benzene:acetone (100:60:6.7). The BaP-containing spot on the plate was scraped off and eluted with acetone. The acetone solvent was then exchanged with n-octane. Quantitative determinations of the BaP dissolved in the n-octane solutions were carried out by fluorescence analysis using the Shpolsky effect (Shpolsky et al., 1952; Fedoseyeva et al. 1968) at 196°C on a AOC-12 spectrograph using appropriate standards. BaP and others. Sensitivity of the method allowed quantitation of BaP down to 1x10 '"g/ml. with an error of less than 10%. Determination of Benzo(a)pyrene in Sediment and Biota Bottom sediments, plankton, and neuston were crushed to a powder. Portions of 3 to 5 g were extracted using 200 ml of benzene in a Soxhlet unit for 12- to 18-h periods. After concentration and chromatographic separation by thin layer chromatography on alumina plates using a (9: 1 ) benzene:acetone developing solution, the BaP spots were scraped off and quantitatively analyzed using the fluorescence technique discussed earlier. Results and Discussion The Third Joint US-USSR Bering & Chukchi Seas Expedition ( August to September 1 988 ) studied biogeochemical cycling of PAH's in marine ecosystems of the northern oceans using benzo(a)pyrene as a model compound. The expedition was a continuation of previous investigations in the Bering Sea ( Izrael eta!., 1987), and also was expanded to include the Gulf of Anadyr, the Chirikov basin and the Chukchi Sea, where this work was carried out for the first time. By positioning the sampling locations where work began in 1981 and 1984, as well as positioning them at new stations in the Gulf of Anadyr, we were able to cover both the deep- water areas of the Bering Sea (the East and South Polygons) and the northern shallow-water areas of the continental shelf. At the high latitude stations, BaP concentrations exceeded 10 ng/1 in 28 of the 45 surface water samples. The highest concentration values that were measured in these regions are shown in Fig. 1 for the water. Fig. 1. Distribution of the the highest benzo(a)pyrene concentrations (those >5 ng/1 ) measured in waters of the Bering and Chukchi Seas ( August 1988). The BaP spatial distribution in water of the southern Bering Sea and East, South, and North Polygons was generally homogeneous, without the spottiness characteristic of the previous expeditions (Tsyban et al., 1986; Volodkovich etal., 1987). The average concentration in the seawater was 3.5±0.48 ng/1. Notice that even taking into account all of the values, including the highest ones (up to 80 ng/1), the average BaP concentration did not exceed 9.3 ng/1, which is much below the levels recorded on the previous expedition in 1984. The majority of the BaP concentrations in the Bering Sea in August 1988 fell between 2 and 5 ng/1, which corresponded to the natural low levels of BaP in seawater reported by other investigators. In many cases, the maximum values found were only 0.4 to 0.6 ng/1. The highest BaP concentrations were 309 64 to 85 ng/1 (the East Polygon and the Chirikov basin) and 185 ng/1 in the Bering Strait. These high levels were found in photic layers of the water column (0.5 to 25 m). At the same time, BaP concentrations up to 40 ng/1 were recorded in deep water 1,000 to 3,000 m, the East Polygon, Station 3; and 20 ng/1 at the South Polygon, Stations 109 and 1 10. The BaP vertical distribution was also relatively homogeneous and, unlike the 1984 samples, did not tend to accumulate in the surface samples. However, 14 maxima out of the 42 that were measured (18% of the total number) corresponded to the 0.5 and to the 1 1 to 25 m horizons. The most homogeneous vertical distribution of low BaP levels was found in samples from the southern area of the Gulf of Anadyr (Station 6 — 0.6 to 1 .6 ng/1 ), in the central part of the Gulf of Anadyr (Stations 22, 24, and 27—0.8 to 4.0 ngA) and in the 10 to 500 m water layer at the East Polygon where it was 1 to 6 ng/1. The South Polygon contained BaP concentrations in the water between 1 to 21 ng/1, with those samples in the 0.5 m surface layer at 4.15 ng/1. The average for this entire station was 4.15 ± 0.37 ng/1. The highest BaP concentrations were found in deep water ( 1 ,000 to 3,000 m) in the western part of this polygon at Stations 109. 110, and 111. The southwest Station 1 1 1 showed relatively high concentrations at 0.5 and 45 m depths; this area also produced higher levels in 1984. At Station 1 13, which was east of the South Polygon, the BaP concentrations at the depth range of 25 to 2,000 m were characterized by considerable homogeneity, 1 .2 to 3 ng/1, and only in surface water (0 to 1 0 m ) were the levels higher, ranging from 8 to 13 ng/1. At the East Polygon, the BaP concentrations at the depth of 1,000 m was also relatively homogenous and low. 1 to 3 ng/1, which was the same in 1984. However, some individual horizons showed BaP concentrations that were among the highest concentrations found in 1988 (i.e., 25 to67 ng/1). Also, some of the highest values recorded in 1988 were at the 0.5 m layer (up to 59 ng/1) and at the depths of 100 to 1 .000 m (see Fig. 1 ). Note that the highest BaP concentration recorded in 1984 in the southeast part of this sampling area was 46.6 ng/1. The average BaP value in the East Polygon water was among some of the lowest compared with the other areas tested this year (i.e., 3.34 ±0.54 ng/1). The Gulf of Anadyr was investigated for the first time. It showed a pronounced BaP homogeneity and was uniformly characterized by low levels of 0.5 to 5.8 ng/1 (93% of the determinations). At anumber of stations, the BaP concentration throughout the whole water depth varied over even a smaller range (i.e., 1 to 3 ng/1). The exceptions were the 3 stations in the southern part of the gulf where the concentrations in the surface horizons ( 10 to 25 m) ranged from 1 6.5 to 23.9 ng/1 ( see Fig. 1 ). The average BaP value for the entire area of the Gulf of Anadyr was 2.22 ± 0.22 ng/1, the lowest among all the investigated northern regions. On the shelf near St. Lawrence Island, in the water of the larger part of the investigated horizons of the North Polygon, low BaP concentrations of 1 to 6 ng/1 dominated, with the average value being 3.68 ± 0.65 ng/t. The most homogeneous BaP distribution with depth was observed in the southern part of this polygon. Higher concentrations, up to 25 ng/1 in the 1 0 to 25 m horizon and 34 to 52 ng/1 in the 0.5 meter surt'ace layer were confined to the northern part of this region nearest to St. Lawrence Island (see Fig. 1). However, these recorded maxima were lower than in 1984. At higher latitudes the BaP distribution was characterized by generally higher concentrations. The water of the shallow Chirikov basin, the area between St. Lawrence Island and the Bering Strait, contained an average BaP level of 4,63 ± 0.54 ng/1. with the maximum values for individual samples being 2 to 4 ng/1. However, most stations ( see Fig. 1 ) at the 0 to 25 m depths showed increased BaP levels up to 68 to 85 ng/1. The highest BaP concentrations, both for this area and other areas in the north, were recorded at the 45 m depth in the western part of the Bering Strait that had a value of 185 ng/1. Of considerable interest are the samples that were collected for the first time from the southern part of the Chukchi Sea ( Stations 44 to 8 1 ). In the southern region of this investigated area, the BaP concentration over the water depth profile, including the surface layer, was within 0.8 to 3 ng/1; however, in the northern part of this area, BaP concentrations up to 15-56 ng/1 were measured, with maxima near the Alaska coastline (Station 64). The distribution of the high BaP water plume covered quite a pronounced area interacting in the north with the floating sea ice boundary (see Frontispiece station map). The vertical BaP distribution in this relatively shallow area (50-60 m) did not have any pronounced stable maxima since the higher BaP levels were found throughout the whole water depth from the surface to near-bottom horizons. Special note should be taken of the BaP concentrations in the samples of sea ice and the water collected from the surface microlayer (0 to 200 |a) that were taken at 68°N latitude. (Station 45). These values were 13 to 18 ng/1 and 20 ng/1, respectively. There was significant BaP concentration in the ice. With considerable ice areas occurring in the Chukchi Sea even in summertime, this would indicate that there is a potential danger from PAH accumulation in this substrate and the levels are reaching those that might pose a real threat to this vulnerable northern sea ecosystem. The results of this investigation show a wide distribution of BaP in the water and even ice cover of this subpolar region. The most frequently occurring concentrations were low levels, near the natural levels of 5 ng/1, with the BaP concentrations slightly higher at the northern latitudes (65°N latitude and higher). It was at these latitudes that most of the higher BaP concentrations (60-80 ng/1) were found. These areas include the East Polygon (deep water horizons) and the North Polygon (northern stations), as well as several locations in the Chirikov basin and the northern part of the investigated regions of the Chukchi Sea. Not only is BaP present in the waters of the Bering Sea and the Chukchi Sea, it is also found in the bottom sediments of these regions. In 1988, BaP was recorded in sediment at most of the 43 investigated stations. The exceptions were only 6 of the 43 locations that were in the southern part of the Gulf of Anadyr ( Station 6 and 7 ), to the north from St. Lawrence Island (Station 102), and along the Alaska coast (Stations 66, 310 67, and 52). It should be noted that the BaP concentration in the near-bottom water at these stations also had the low values (0.6 to l.Ong/1). In other regions the BaP concentrations in the upper 5 cm layers of the sediment, which are the primary areas of PAH accumulation (Bourcart era/., 1961; Larsene/a/., 1983), were within 0. 1 1 to 1.7 )ig/kg of dry mass. The maximum BaP concentration (4.5 |ig/kg) was measured in the shallow water of the northern section in the Chukchi Sea (Station 49). A high BaP concentration (0.87 |ig/kg) was also measured in the Gulf of Anadyr at Stations 12 and 13 near the Chukchi coast, and (1.7 |ig/kg) Station 43, and also in the center of the North Polygon where it was 0.87 |J.g/kg. The general character of BaP distribution in bottom sediments may be represented by the contours presented in Fig. 2. It is evident that the spatial BaP distribution in bottom sediments has quite a sophisticated structure with pronounced concentration maxima regions. The position of areas with maximum BaP concentrations in the sediment correspond to the central portions of the northern section of the Gulf of Anadyr, St. Lawrence Island, the central part of the Chirikov basin, and the Central part of the investigated area of the Chukchi Sea. 1 • 0 9 BaP content _ IL^ 0 6 mg/kg dry weight [7] BaP content undetermined Chukchi Sea Bering Sea H Fig. 2. Concentration contours for BaP measureii in the lop 5 cm-layers of sediment in the Bering and Chukchi Seas (August 1988). BaP accumulation was recorded in bottom sediments (Tsyban et al., 1987) in previous studies as well (1981 and 1984). Incidentally. BaP levels at a number of sampled stations showed no significant change over this time (Fig. 3 ), indicating 11 '^°"h I ^ Polygon (-P Bering Sea o 1 tdSl Polygon South Polygon I I D- 02 1988 BaP content mg/kg dr>' weight Fig. 3. Comparisons of the concentrations of BaP measured over time in surface sediments collected in 1981, 1984 and 1988 from similar locations in the Bering Sea. a relatively constant processing of this constituent at these locations. However, in general the total BaP accumulation in bottom sediment of the Bering Sea and the Chukchi Sea is 1 to 2 orders of magnitude lower than in impacted sea systems ( Tsyban etal.. 1985} and corresponds to the levels characteristic of relatively clean regions such as the western coast of Greenland (Mallet e/ a/., 1979). Benzo(a)pyrene distribution in the seawater showed a significant impact on the biotic component of this system, which was expressed, in particular, in the accumulation of this toxic compound in aquatic biota, especially in the phytoplankton. Earlier, in the investigated periods of 1981 and 1984. we showed their presence in all of the samples of plankton taken in the Bering Sea (phytoplankton and zooplankton). Its content in plankton organisms was at the level of 10' to 10' |ig/kg dry wt. In 1988. BaP was recorded in all 26 samples of plankton organisms taken at 22 stations in the Bering Sea and the Chukchi Sea. and in most cases. BaP content in plankton was within 0.2 to 0.9 |ig/kg (469^ of the samples) and 2.0 to 2.6 |ig/kg (23% of the samples). As one can see from Fig. 4. the highest BaP accumulation in plankton in the Bering Sea, 10.2 to 10.6 |i g/kg, was in the areas in the northern part of this area near the shallow water of the St. Lawrence Island, the North Polygon, and Station 100 in the Chirikov basin. 311 BaP content, mg/kg dry weight in biota 10-n Chukchi Sea : I Polygon '---■1® 1 Fig. 4. Distribution ofthehighestconcentrationsofBaPmeasured in plankton and neuston collected in the Bering and Chukchi Seas (August 1988). In the Chukchi Sea, the area of the highest BaP accumulation by plankton was located along the highest latitudes, with the maximum 12.6 |ig/kg occurring at Station 49. It should be especially noted that the maxima for BaP accumulation in plankton were found at those stations (35,1 00, and 49) that were also characterized by the maximum BaP levels found in bottom sediments. This fact is most pronounced at the northern section of the Chukchi Sea (Station 49): 12.6 and 4.5 )Jg/kg, respectively. These facts may indicate the primary role of biosedimentation processes in deposition of pollutants to bottom sediments — in particular, in highly productive shelf regions of the arctic seas. Plankton communities are particularly sensitive to changes of the hydrochemical background. Due to some physical and biochemical processes, PAH accumulation in plankton often exceeds the concentration in their habitat by 15 to 165 times. This process can be indicated by the coefficient of BaP accumulation by plankton organisms or the biomagnification coefficient ( ratio of BaP concentration in plankton to that in the water, Cp:Cw). In 1988, the most significant BaP accumulation was recorded at the East and North Polygons as well as in the Chirikov basin (Station 100), where accumulation coefficients were3.9x 10-,3.8x 10-,and2.0x 10-. In the other investigated regions, these values were within 0.2 x 10' to 8.8 x 10' (Table 1 ), which is comparable with the data obtained for these regions in 1984. Note that in 1981 the accumulation coefficients were higher than observed here with some as high as 1 0^ and 1 0\ A reason for these differences could be that in 1981 there was a higher BaP content in every element of the Bering Sea ecosystem than was present during the 1988 cruise. Benzo(a)pyrene accumulation was also discovered in the neuston community populating the surface layer of the seawater. Benzo( a)pyrene accumulation in neuston was comparable with that in plankton and had the values of 0.6 to 10.0 |ig/kg dry wt. (Table 2 and Fig. 4). Eleven investigated samples show relatively high BaP concentrations for neuston organisms from the Bering Sea — in particular, in the Gulf of Anadyr and the East Polygon (Fig. 4). These facts are evidence for a selective trend towards higher PAH accumulation in the biotic component of these ecological systems. Comprehensive investigations of PAH biogeochemical cycles carried out in this region of the world's oceans showed a widespread BaP distribution in the Bering and the Chukchi Sea ecosystems. The general character of BaP distribution and their accumulation in components of marine ecosystems testifies to the fact that even though the degree of pollution of these aquatic systems is not high, carcinogenic PAH's constitute a constant and characteristic feature for most regions of the Bering Sea and Chukchi Sea. 312 TABLE 1 Concentration of benzo(a)pyrene in plankton in the Bering and Chukchi Seas. August 1988. Area of Investigation Station Concentration of Benzo(a)pvrene No. In water, at In plankton collect site ng/kg wet wt. (C,) ng/1 (C.) Accumulation Factor for Plankton (C./C,) East Polygon Test Area 52 4.0x 10' Gulf of Anadyr 9 13 16 2.1 0.8 3.1 835 70 40 39 X 10' 8.8 X 10' I.3x 10' North Polygon Chukchi Sea Chirikov basin 36 47 49 50 52 56 57 72 89 92 100 2.7 8.4 12.5 7.2 6.4 0.9 1.7 1.4 4.3 6.8 5.2 1.020 560 1,260 378 459 90 22 200 86 63 137 1,063 38 X 10' 6.7 X 10' lOx 10' 5.8 X 10', 6.3 X 10' I.4x 10' 2.4 X 10' I2x 10' 6.1 X 10' I.5x 10' 0.2 X 10' 20 x 10' TABLE 2 Concentration of benzo(a)pyrene in neuston of the Bering and Chukchi Seas, August 1988. Sampling Area Station Number Concentration of Benzo(a)pyrene (|ig/kg wet wt.) East Polygon Test Area 2.5 1.2 1.94 Gulf of Anadyr 16 22 27 2.43 lO.O 3.0 Chukchi Sea 50 53 56 69 74 0.7 0.6 0.7; 0.8 7.8 1.9 313 Subchapter 8.3: Fate of Heavy Metals 8.3.1 Heavy Metals in Water and Sediment TATIANA P. KOLOBOVA and LYUDMILA G. MANYAKHINA Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR Introduction Materials and Methods Among numerous pollutants coming to the World Ocean, the greatest potential threat is posed by chemicals that have global distribution, continuous input, and pronounced adverse effect on living creatures. These substances include heavy metals. These and other substances may cause serious ecological changes on aglobal scale. Therefore, studying theiroccurrence and distribution may help us avoid their damaging effects. Pollution of the World Ocean by toxic metals is a most telling example of a global anthropogenic effect. Today there are practically no regions in the world oceans that do not contain increased levels of trace metals. Analysis of the modem data (Izrael & Tsyban, 1981) shows that millions of tons of toxic metals come to the world oceans every year. It is established ( Izrael & Tsyban, 1981; Sapozhnikov, 1982) that in recent years the anthropogenic components of some pollutants (including lead, mercury, arsenic) is comparable to and even exceeds natural flows of these elements to the world oceans. The present concentrations of toxic metals in the world oceans varies from single digit to hundreds of ng/1, which considerably exceeds (5 to 10 times ) their natural concentration in seawater. Being intrinsic constituents in the habitat, metals, when exceeding their natural concentrations in these habitats, can render an adverse effect on living creatures (Florence, 1983; Yablokov& Ostroumov, 1983). In view of the above, investigation of toxic metal behavior, as well as processes of their accumulation and distribution in sea ecological systems, takes an important place among environmental pollution problems. However, their concentration is usually lower than those of such widely spread pollutants as oil products and chlorinated hydrocarbons. At the same time, one has to note that, regardless of several serious studies aimed at evaluation of the World Ocean pollution by toxic metals performed in the last decades, individual seas, specifically those in the so-called background regions of the ocean, are still insufficiently studied. The present state of knowledge does not provide any complete concept of the processes of metal accumulation and distribution in ecological systems of these seas. Meanwhile, some of these seas — in particular, the Bering Sea and the Chukchi Sea — belong to the most productive and more used regions of the world oceans. That is why a study of toxic metal accumulation and distribution processes in such ecological systems, as well as their interaction with the environment, is of special interest. This paper discusses distribution of trace metals in water and bottom sediments of the Bering Sea and the Chukchi Sea on the basis of studies performed by the Third Joint US-USSR Bering & Chukchi Seas Expedition. The cruise track covered the larger part of the sea regions in this area, including shallow water and coastal areas as well as deep-water regions. Water was sampled using Niskin plastic bathometers. Preliminary treatment of samples was done using standard procedure described in detail in the Methodological Foundations of Integrated Ecological Monitoring of the Ocean (Tsyban etai, 1988). The top layers of the bottom sediments were sampled without disturbance of the stratification, using an OKEAN-50 dredger with 0.25 m- coverage area. After the samples were air dried at 20 to 25°C, they were sealed in plastic bags for storage. Further treatment of sediment samples was performed in the permanent coastal laboratory using the procedure described by Prokofyev and associates (Prokofyev et al, 1981 ). Solutions, resulting from acid digestion of the samples, were tested for metal concentrations using flame atomic absorption spectroscopy. Results and Discussion Tables 1 and 2 show the trace metal concentration in water and bottom sediments of the Bering Sea and the Chukchi Sea. Comparison of the data shows inhomogeneity of metal distribution in the water of the regions in question. For instance, concentrations of copper varied from 0.01 |ag/l (in the Gulf of Anadyr) to 0.46 |ig/l in the open areas of the Bering Sea (Station 109), with an average value of 0.08 |ig/l. Shallow- water stations ( up to 1 00 m deep ) demonstrated a direct relation between copper concentration in water and bottom sediments: a larger copper concentration in water is accompanied by its larger concentration in bottom sediments. Such a correlation was not found at the deep-water stations. In general, copper concentration in bottom sediments of the Bering Sea varied from 9.32 |ig/g dry wt. in the open areas of the Bering Sea up to 38.32 ng/g dry wt. in the Gulf of Anadyr with the average value 17.0 |ag/g. Sediments of the Chukchi Sea contained a significantly smaller copper concentration — found near the Alaska coastline ( Station 64 ) and the smallest one (4.6 jJg/g) near the arctic coast 317 of Chukthi (Station 59) — than in the other areas that were sampled. For the Bering Strait, in this shallow-water area, the copper concentration in bottom sediments only reached a maximum of 3.56 Hg/g. Cadmium showed a similar heterogeneity of distribution. In general, cadmium concentration in water varied from 0.0 1 to 0. 1 3 |ig/l in the Chukchi Sea. Cadmium concentration in the Bering Strait water was below the level of detection. The highest cadmium concentration (3.69 (ig/1 ) was found at Station 24 in the surface water layer, which is probably related to local geographic conditions. Cadmium distribution in bottom sediment showed little variation in its concentration and was generally low and of little significance, with average concentrations being 0.6 ng/g dry mass in the Bering Sea, 0.4 |ig/g in the Chukchi Sea, and 0.2 |ig/g in the Bering Strait. TABLE 1 Metal concentrations in the water of the Bering Sea and the Chukchi Sea. Station Horizon Concentration, |a g/1 (meters) Cu Cd Mn Zn Pb 1 0 _• 0.65 _ _ _ 25 0.06 0.06 0.04 0.30 2.05 2 30 - - - 0.46 0.02 100 - - 0.01 - 0.09 5 130 0.46 - 0.01 3.67 - 7 20 0.07 0.06 0.04 0.15 1.03 100 0.10 0.11 0.06 2.85 0.41 9 20 - - - - - 60 - - - 0.39 - 13 5 - - - - - 15 5 0.01 - - - - 75 - - - - - 24 IIMC 0.09 3.69 3.6 0.12 - 75 0.09 - 0.01 - 32 50 0.06 - - - 50 10 - - - 0.01 - 57 10 0.08 0.03 0.02 - 0.57 59 10 0.07 0.13 0.02 0.29 2.34 64 10 0.03 - - - - 69 10 - 0.01 0.02 - 1.29 72 10 0.17 - 0.04 2.13 0.07 74 10 0.016 - 0.01 - - 83 10 0.68 - 0.03 - - 86 10 0.08 - - 3.30 - 96 10 0.01 - - - 1.23 100 10 - 0.02 0.02 - 0.10 108 10 - O.ll - 0.76 1.87 109 1000 0.49 0.29 0.40 113 0.03 - - - - TABLE 2 Metal concentration in the bottom sediments of the Bering Sea and the Chukchi Sea (|J.g/g dry weight). Station Cu Cd Mn Station Cu Cd Mn 2 15.40 0.36 208.00 32 10.5 166.00 3 18.90 0.56 236.40 47 11.2 0.42 238,00 5 33.50 0.21 758.40 52 10.8 0.87 241.60 6 17.50 592.40 55 11.4 - 259.40 7 10.50 0.09 189.20 59 4.6 - 88.40 8 21.50 0.92 290.40 63 9.56 0.35 193.62 8(0.3) 18.90 0.54 258.40 64 12.52 0.77 209.02 8(1.2) 20.10 0.70 281.20 74 4.58 0.17 89.62 8(2.0) 20.10 0.68 271.40 92 2.24 0.03 83.82 8(5.0) 20.30 0.76 176.80 69 7.72 0.46 148.22 9 16.78 0.95 216.60 76 9.84 0.59 186.42 18 9.32 0.57 182.20 89 3.56 0.22 98.62 19 8.76 0.59 146.00 96 6.32 0.15 144.22 27 11.42 0.61 141.20 100 2.68 0.15 83.82 22 15.16 0.88 189.00 104 2.72 0.19 85.22 29 38.32 1.58 860.42 110 65.92 3.10 5,996.42 Note: Metal concentration is below sensitivity of method. (0.3) - depth of bottom sediment sampling, m. Metal concentration is below sensitivity of the method. The study of manganese distribution in the investigated ecological systems showed an extremely low concentration in seawater, except for Station 109. The concentration of manganese did not exceed 0.04 |ig/l ( see Table 1 ) . The average manganese concentration in bottom sediments was 220 |ig/g dry wt. These data are consistent with the results of Loring (1984) obtained for bottom sediment samples (340 |4g/g) taken near the Arctic coast. The high concentration of manganese (5,996.4 |ig/g) observed at Station 29 is, probably, related to manganese remobilization processes in this region of the bottom. Concentrations of zinc and lead were determined only in samples of seawater. The concentration of zinc in the Bering Sea varied from 0.15 |ag/l (central part) to 3.67 |ig/l (eastern part), and the concentration of lead varied from 0.02 |ig/l (eastern part) to 1.03 |ig/l (central part). The concentration of zinc and lead ranged from 0.01 to 2.13 |ig/l and 0.07 to 2.34 |ig/l, respectively. In conclusion, it should be noted that our results for metal concentrations in water and bottom sediments of the Bering Sea and the Chukchi Sea are close to the values obtained by other investigators (Hegge, 1982: Maeda, 1986; Hegge etai. 1987). Thus, studies from the Third US-USSR Joint Bering & Chukchi Seas Expedition verify that metal concentrations in water and bottom sediments of the Bering Sea and the Chukchi Sea are still at background levels. 318 8.3.2 Baseline Levels of Certain Trace Metals in Sediment and Biota ALEXANDER J. KRYNITSKY* , CLIFFORD P. RICE* . and PASQUALE F. ROSCIGNO* 'US Emironmental Protection Agency. Beltsville, Maiyland. USA ' US Fish and Wildlife Service. Patuxent Wildlife Research Center, Laurel. Maryland. USA *US Fish and Wildlife Sen'ice. National Wetlands Research Center, Slidell. Louisiana, USA Introduction The Bering and Chukchi Seas are believed to be relatively free from pollutants due to sparse human coastal populations and limited industrial development. Increased industrial activity, especially in petroleum exploration and production, is proposed for the future and thus preliminary studies in determining baseline concentrations of environmental contaminants are necessary. Up to now, there have been no comprehensive studies in determining baseline concentrations of trace metals in sediment and biota in the Bering and Chukchi Seas by the US or USSR. The US Fish and Wildlife Service was concerned that tissues collected from Pacific walruses (Odohenus rosmarus divergens) in the Bering Sea were high in cadmium (Taylor et al., 1989). For example, the maximum concentrations of cadmium were 50 ppm (wet weight) in the liver and 99 ppm (wet weight) in the kidney. Cadmium residues in verteSrate kidney or 1 i ver that exceed 1 0 ppm ( wet weight ) or 2 ppm whole body (wet weight) should be viewed as evidence of probable cadmium contamination (Eisler, 1985). Taylor et al. (1989) recommended that additional studies be conducted on cadmium contamination since levels exceed the safe levels of human consumption. Under the auspices of a cooperative program between the US and USSR, we conducted this study in order to help address the above issues. During the Third Joint US-USSR Bering & Chukchi Seas Expedition our purpo.se was to determine baseline concentrations of arsenic, cadmium, cobalt, copper, lead, manganese, and mercury in the sediment. Cadmium, arsenic, lead, and mercury were determined in biota. Trace metal results obtained by sediment analysis, unlike seawater analysis, are generally well above the analytical detection limit and contamination risks of the sediments from sample handling are insignificant (Szefer, 1988). Sediment data are, therefore, utilized as a tool for assessing sources and distribution of some elements in aquatic environments. We investigated trace metals in biota to determine if lower trophic organisms bioaccumulate these metals. This may explain high concentrations of cadmium in walruses further up the food chain. On this expedition we collected bivalves (Nuculoidae). hermit crabs (Paguridae), sea urchins (Strongylocentrotidae). shrimp ( Pandalidae), neuston, zooplankton, and phy toplankton. Materials and Methods Samples were collected from the Bering and Chukchi Seas while aboard the research vessel Akademik Korolev from 26 July to 2 September 1988. The stations were determined by the chief scientists from both the US and Soviet sides and the samples were collected opportunistically from each station. The stations sampled are shown in the preface to this book and the numbering corresponds to that shown in this figure. The zooplankton and phytoplankton were collected by net tows performed by the Russian scientists and described in Chapter 5 (this volume). The neuston samples were collected by Soviet scientists using a special surface trawl also described elsewhere in this text. Samples were placed in chemically cleaned I-Chem jars (I-Chem Research Inc., New Castle, Delaware). The excess water was decanted and the samples stored frozen until they were prepared for trace metal analyses. A bottom trawl, designed and operated by Soviet scientists, was used to obtain the benthos samples (shrimp, crabs, bivalves, and urchins). These samples were either placed in I-Chem jars or, for larger samp' .>, placed in plastic Whirl-pak bags, and frozen for storage. The sediment samples were obtained using a 30 cm- box corer provided by Texas A&M University. Surface layers (0-2 cm) of each sediment sample from the box corer were scooped with a teflon spatula and placed directly into precleaned I-Chem jars. The samples were frozen until trace metal analysis. Analysis Sediment Sediment samples for arsenic, cadmium, cobalt, copper, lead, and manganese were digested as described by Krynitsky ( 1987), with modifications for the above metals. A 2.0 g (wet weight ) aliquot was placed into a 50 ml polypropylene centrifuge tube and 5.0 ml of nitric acid and 0.5 ml of 30% hydrogen peroxide were added. The Krynitsky method was modified in that 5 ml of hydrofluoric acid were added in order to free the analytes from the silicates contained in sediments. The samples were allowed to digest for 2 h in a hot water bath at 90°C (Krynitsky, 1987). After digestion, the samples were diluted, shaken, and centrifuged prior to analysis. 319 A Perkin-Elmer Model 5000 flame atomic absorption spectrometer was used to analyze for copper, cobalt, and manganese. The parameters are described in the instrument's operations manual (Perkin-Elmer Corp., 1976). A Perkin-Elmer Zeeman Model 3030 graphite furnace atomic absorption spectrometer (GFA AS ) was used to analyze for arsenic, cadmium, and lead. The GFAAS conditions for arsenic are described by Krynitsky (1987). The GFAAS conditions for cadmium and lead are described by Hinderberger (1981). Separate 5.0 g (wet weight) aliquots of sediment were digested for mercury analysis under reflux in sulfuric and nitric acids (Monk, 1961). The determinations were performed by cold vapor atomic absorption spectroscopy (CVAAS) using a Coleman MAS-50B-Mercury analyzer. The detection limit for arsenic, lead, and cadmium was 0.05 ppm based on a 2.0 g sediment sample. The detection limit for mercury was 0.01 ppm based on a 5.0 g sediment sample. The detection limit for copper and cobalt was 0.2 ppm and that for manganese was 1 .0 ppm, based on a 5.0 g sample. All sediment analysis was based on wet weight. Biota After each station, samples were combined by family name for analysis. The digestion procedure for cadmium, lead, and arsenic was described by Krynitsky (1987). The entire sample (including shell in the benthos) was homogenized in a Virtis Model 45 blender. A 0.5 g wet weight aliquot of tissue was digested in 5 ml of nitric acid and 0.5 ml of 30% hydrogen peroxide as described above. Determinations for lead and cadmium were performed using the instrument parameters described by Hinderberger (1981) and arsenic as described by Krynitsky ( 1987). The detection limit for lead and cadmium was 0.05 ppm and that for arsenic was 0. 1 ppm, based on a 0.5 g sample wet weight. For mercury 1 .25 g were digested and analyzed according to the procedure described by Monk ( 1 96 1 ). "The mercury determinations were performed using a Spectro Products mercury analyzer equipped with a Varian VGA-76 vapor generation accessory. The detection limit for mercury was 0.05 ppm based on a 1.25 g sample wet weight. Moisture Determimitions Moisture determinations were performed by weighing out a separate 1.0 g of aliquot of biota or sediment into a tared aluminum pan. The sample was allowed to dry for 24 h at 1 10°C and the percent of moisture was calculated. Quality Assurance/Quality Control The samples were processed in batches of 1 0 to 20 samples with one matrix spike, one procedural blank, one duplicate sample, and one standard reference material (SRM) for each batch. The SRM used for sediments was provided by the National Institute of Standards and Technology (NIST), fomierly National Bureau of Standards. The SRM used was NIST 1 646 Estuarine Sediment, which contained the following certified values (ppm dry weight) for the metals of interest: arsenic 11.6±1.3, cadmium 0.36 ± 0.07, and cobalt 10.5 ± 1.3 . The SRM used for biota was provided by the National Research Council of Canada, Ottawa, Ontario, Canada. The SRM used was TORT- 1 , which is a freeze-dried sample of a partially defatted lobster. TORT- 1 contained the following certified values (ppm dry weight) for the metals of interest: arsenic 24.6 ± 2.2, cadmium 26.3 ±2.1, lead 10.4 ± 2.0, and mercury 0.33 ± 0.06. The matrix spike for the sediment consisted of : 300 ^g manganese; 10 |ig each of lead, copper, cobalt, and cadmium; 20 fig arsenic; 0.5 |ig mercury. The matrix spike for the biota consisted of (6.0 |ig arsenic and 5.0 |ig each of cadmium, lead, and mercury. Recoveries were monitored in both the standard reference materials and matrix spikes. The average recoveries ranged from 87-108% for the metals we investigated. The relative percent differences between duplicate results averaged less than 10%. Results and Discussion Trace metals, with the exception of mercury at a few stations, were present in all sediment samples collected in the Bering and Chukchi Seas (Table 1). The one deep-water station (Station 3) differed from the shallow- water stations in that mai]ganese and copper were much higher. This was probably due to the remobilization of these metals within the sediment core as a primary mechanism. Other investigators during the Second Joint US-USSR Expedition to the Bering Sea (Summer 1 984 ), who sampled more deep-water stations in the Bering Sea than were sampled during this cruise, observed the same phenomenon with these two metals (Iricanin & Trefry, 1991). When comparing the concentrations of trace metals obtained in sediments during the 1 988 cruise to those obtained during the 1 984 cruise (Table 2 ), the concentrations of lead and cadmium are generally higher for the 1988 cruise. During the 1988 cruise the stations sampled were primarily shallow-water stations (<200 m) where the primary productivity was high (Zeeman, Subchapter 6.2, this volume), and during the 1984 cruise the stations sampled were the deep-water stations (>600 m). These higher concentrations were most likely due to a downward vertical flux of planktonic organisms and other biogenic debris (Iricanin & Trefry, 1991). In general, the values for trace metal residues obtained from both the 1984 and 1988 cruises appear to be less than value for trace metals in sediments from some other parts of the world (Table 2), which suggests that the Bering and Chukchi Seas are relatively pristine. Only arsenic, cadmium, and lead had reportable values in the biota (Tables 3,4). The values of mercury in the biota are less than the detection limit. The benthos samples might be expected to have residue patterns similar to the sediments they reside in except in cases where bioavailability plays an important role. Even though the lead values in the sediment were 30 to 40 times higher than those for cadmium, the cadmium values in the benthos were in most cases higher than the corresponding lead values. This indicates that the benthos investigated bioaccumulated cadmium better than lead. Lead values were also comparable to the arsenic values in the sediment. As with cadmium, we found that the arsenic values in the benthos were 320 TABLE 1 Trace metal concentrations, ppm dry weight, for surficiai sediments (0-2 cm). A. Trace metal concentrations in sediments from the Bering Sea. Station Depth No. (meters) Pb Cu Mn Co Cd Hg As 3 3,092 8.5 31. 910. 7.4 0.35 0.06 3.5 7 140 7.9 13. 390. 8.5 0.24 <0.02 8.3 9 107 9.7 16. 360. 10. 0.46 0.033 14. B. Trace metal concentrations in sediment from the Gulf of Anadyr. Station Depth No. (meters) Pb Cu Mn Co Cd Hg As 13 148 7.4 6.5 290. 7.6 0.24 <0.02 9.8 18 75 9.5 13. 410. 8.4 0.17 0.026 19. 22 88 17. 14. 390. 6.9 0.46 0.063 14. 35 63 16. 13. 370. 10. 0.47 0.045 13. C. Trace metal concentrations in sediment from the Chukchi Sea. Station No. Depth (meters) Pb Cu Mn Co Cd Hg As 45 47 50 55 59 61 64 67 69 45 49 48 46 38 49 45 35 41 17. 16. 340. 15. 11. 350. 16. 10. 490. 5.2 6.7 220. 11. 7.8 210. 7.4 8.4 190. 4.7 6.3 220. 6.5 6.1 250. 7.8 8.2 300. ^^^ TABLE 2 9.2 0.39 0.036 20. 8.9 0.29 <0.02 12. 1. 0.16 <0.02 12. 5.5 <0.10 <0.02 6.2 5.6 0.13 <0.02 10. 5.7 0.32 0.025 7.2 4.7 <0.10 <0.02 6.0 5.3 0.13 <0.02 6.8 6.7 0.13 0.022 6.8 Comparison of the average values of trace metals in sediment obtained during the 1988 Joint US-USSR Expedition to other values of trace metals in surficiai sediments from different parts of the world. ppm Dry Weight Pb Cu Mn Co Cd Hg As Bering Sea 1988 8.7 ± 0.075 20 ± 7.9 553 ±252 8.6± 1.1 .35 ± .09 .03 ± .02 8.6 ±4.3 Gulf of Anadyr 1988 13 ±4.1 12 ±3.0 365 ± 46 8.2 ± 1.2 .34 ±.13 .03 ± .02 14. ±3.3 Chukchi Sea 1988 10±4.6 8.9 ±2.9 285 ± 90 7.0 ±2.1 .17±.13 <0.02 9.6 ±4.3 Bering Sea 1984- 3.5 ± 1.9 22 ± 12 362 ± 46 NA' .14±.13 .04 ± .03 NA Southem Baltic- 330. 52. 540. 21. 2.9 NA NA Ivory Coast West Africa' 93. 55. 190. NA NA 280 NA 'NA - Not analyzed. "Data from the Second Joint US-USSR Expedition to the Bering Sea, Summer 1984 (Iricanin & Trefry, 1991). •"Data obtained from Szefer er al. 1988. "Data obtained from Kouadio ei uL, 1987. 321 TABLE 3 Trace metal residues in bivalves, hermit crabs, shrimp, sea urchin, and sculpin from the Bering and Chukchi Seas. Station Common Family Name Number Name 22 Bivalve Nuculidae 35 Bivalve Nuculidae 45 Bivalve Nuculidae 59 Bivalve Nuculidae 59 Bivalve Nuculidae 100 Hermit Crab Paguridae 53 Hermit Crab Paguridae 41 Shrimp Pandalidae 41 Sea ppm Dry- Weight Hg As Pb Cd <0.25 7.8 <0.25 3.2 <0.25 11. 2 2 1.2 <0.25 5.1 0.97 1.3 <0.25 5.1 <0.25 5.2 <0.25 5.9 .031 1.9 <0.25 7.6 0.49 2.4 <0.25 11. 0.33 3.1 Urchin Strongy locentrotidae <0.25 <0.25 13. <0.5 0.75 1.3 3.5 TABLE 4 Trace metal residues in zooplankton, phytoplankton, and neuston from the Bering and Chukchi Seas. ppm Dry Weight Station No. Specimen Hg As Pb Cd 11 Zooplankton <0.25 4.5 215. 6.9 13 Zooplankton NA' 1.5 97. 1.7 15 Zooplankton NA 2.8 17. 1.3 50 Zooplankton NA 1.7 17. 0.75 55 Zooplankton NA 0.99 21. 0.85 57 Zooplankton <0.25 3.8 17. 1.4 52 Phytoplankton NA 1.4 31. 0.90 53 Phytoplankton NA <0.5 11. 0.51 61 Phytoplankton NA 0.59 47. 0.55 64 Phytoplankton NA 0.80 8.1 0.33 69 Phytoplankton <0.25 <0.5 103. 1.3 72 Phytoplankton NA 1.3 118. 1.7 83 Neuston NA 2.0 11. 1.0 86 Neuston <().25 2.8 33. 2.1 NA - Not analyzed. 322 higher than the corresponding lead values. For most marine species, arsenic exists as arsenobetaine, a water soluble organoarsenical compound that poses little threat to human consumption or to the organism (Eisler, 1988). The data indicates that a direct correlation cannot always be made between the residues found in the sediment to those found in the biota residing in that particular sediment. Arsenic values were comparable to the cadmium values in zooplankton and phytoplankton (Table 4). The lead values were probably unrealistically high (8. 1-215 ppm, dry weight), based on work of other investigators (Flegal, 1985). Flegal found that phytoplankton residues, collected from the central Pacific Ocean, contained 0.04 ppm lead (fresh weight) and zooplankton contained 0.05 ppm lead (fresh weight). We suspect that these high values may have been due to contamination from the ship's hull since the paint and rust chips from the ship were known to contain lead. The plankton tows were made only 15 to 20 m below the surface of the water and lead in the plankton and the neuston may have been contaminated by the rust or paint chips. These data should be cautiously interpreted. Cadmium and arsenic concentrations in the plankton and neuston may not have been as severely affected by the ship's contamination, but these findings should be viewed with caution because we do not definitely know the chemical contents of the paint and rust chips from the ship. For example, our values for cadmium (Table 4) were lower than those collected in the northeast Pacific Ocean where Martin et al. (1975) found cadmium concentrations ranging from 2.0 to 5.0 ppm (dry weight) except 10 to 20 ppm (dry weight) off Baja, California. To avoid problems with contamination from the ship, these investigators collected their samples from an inflatable dinghy rowed several hundred meters away from the ship. However, they found their cadmium data to be comparable to their data on the previous cruise when they performed their plankton tows directly off the research vessel. Both arsenic and cadmium tended to be elevated in these marine biota because of their ability to accumulate these contaminants from the seawater or food sources and not due to localized pollution (Eisler, 1985, 1988). We have no reason to suspect that the water column was severely contaminated, even though we did not analyze the water column for arsenic and cadmium. There are, however, cadmium values for water that were collected from the Bering Sea during the Second ( 1984) Joint US-USSR Expedition (Montgomery & McKim, personal communication). During the 1984 expedition, they found cadmium in the water column ranging from <5.0 to 100 ng 1. They used differential pulse anodic stripping voltametry and a rotating disk electrode to make these measurements. Cadmium especially tends to accumulate in a marine organism with the age of the organism (Eisler, 1985). In view of these facts, a likely explanation for the high cadmium concentrations found in walruses by Taylor and coworkers could be linked to longevity and not to pollution sources. To further explain the high concentrations of cadmium in walruses, more research is also needed to determine how much cadmium is bioaccumulated in the food chain. We wish to thank Mark Abramovitz. Steven Boateng, and Brenda Cheek for their able assistance in preparing these samples for analyses. The patience and expert assistance of the crew of the Akademik Korolev are deeply appreciated. We also wish to thank Texas A&M University for the use of their box corer and other coring equipment that was provided to us. 323 Subchapter 8.4: Distribution of Radionuclides 8.4.1 Investigation of Cesium- 137 Distribution in Seawater VLADIMIR I. MEDINETS\ VLADIMIR G. SOLOVIEV\ and BORIS V. GLEBOV 'Odessa Branch of Slate Oceaiwgraphic Institute, Odessa, USSR 'Institute of Global Climate and Ecology, State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR Introduction Nuclear exercises during the last 30 years and modem development of nuclear energy are the main sources of global and regional nuclear pollution of the biosphere, especially the world oceans. The main potential hazard is the accumulation of long-lived radionuclides of anthropogenic origin, such as Sr'*", Cs'", and Pt"", in various natural objects. The stable level of nuclear pollution in the environment (after the banning of nuclear exercises in the atmosphere) was disturbed in 1986 by the accident at the Chernobyl nuclear power station, which led to a massive input of radioactive substances. As a result of this accident, very high concentrations of radionuclides were found in the environment of Europe and the whole of the Northern Hemisphere (Uematsu & Duce, 1986: Buesseler, 1987; Kusakabe et ai, 1988; Nikitin et al., 1988). During the 47th cruise of the Soviet research vessel Akademik Korolev. we investigated the present state of radionuclide contamination in the waters of the Chukchi and Bering Seas based on the distribution of the long-lived radionuclide Cs'". Methods Sampling of large volumes of water (0.8-1.1 m') was carried out at depths of 0 to 170 m with immersion pumps, models 'NIVA' and 'MALYSH.' To selectively concentrate the Cs'" from the sea water, we used fibrous sorbents, "MILTON-T," impregnated with copper ferrocyanide (Vakulovsky, 1986). Aftersampling. the sorbent was ashed in an oven at temperatures not exceeding 450°C. The ash ( 1 0- 1 3 g) was packed hermetically in polyethylene film. Later these samples were transported to the special laboratory of the State Oceanographic Institute (Odessa Branch), where analyses were carried out using the following gamma-spectrometer: — scincilatic (firm LKL WALL AC type COMPU- GAMMA 1282) — semiconductoric (analyzer AMA-0202 with detector DGDK-IOOB) The accuracy was in the range of 10%, and the detection limit was 0.1 Becquerel (Bq). The concentration of Cs'" (the natural radioactive form of cesium) in every sample was less than the detection limit. Therefore, we suggest that the maximum possible concentration of Cs' " in the investigated samples could not be any higher than 0.015 Bq/m\ Results and Discussion The concentrations of Cs' " that were measured during this investigation of the Bering and Chukchi Seas are given in Table 1 . Assuming that the detection limit of Cs'** was the maximum possible concentration of this radionuclide in the investigated areas, and basing this concentration on the initial correlation of Cs'"/Cs"'' activities during the Chernobyl accident, we estimated its influence on the radioactive pollution of the TABLE 1 Concentration of Cs'" in the Bering and Chukchi Seas, summer, 1988. Date Location lat. long. Layer, (ml Average concentration, (Bq/m') 27.07 57°30' N,I74°30'W 0-80 1.6 29.07 57 56 175 04 0-80 2.0 01.08 60 28 177 50 0-120 24 03.08 62 10 179 50 0-60 2.0 04.08 63 00 176 00 0-80 2.3 06.08 64 43 177 50 0-20 1.9 07.08 63 25 172 10 0-60 3.7 09.08 67 44 172 50 0-40 24 10.08 68 40 168 20 0-40 2.2 11.08 67 46 167 19 0-30 2.9 11.08 67 45 168 26 0-40 2.8 14.08 66 55 168 50 0-30 3.2 15.08 66 33 168 30 0-40 2.8 65 58 168 36 0-3 1.8 ■• 65 55 169 22 0-3 1.7 •' 65 50 169 10 0-3 1.6 65 42 169 40 0-3 2.6 " 65 40 168 30 0-3 2.3 •■ 65 38 168 21 0-3 3.3 20.08 65 14 169 21 0-40 2.6 22.08 64 23 169 29 0-30 2.1 27.08 53 59 176 00 0-170 2.2 29.08 53 1 1 177 18 0-90 24 327 Bering and Chukchi Seas. These estimations showed that the maximum of "Chernobyl' s" concentration could not exceed 0.07-0.09 Bq /m\ Taking into consideration that the real concentrations of Cs'" in the Chukchi and the Bering Seas are 1.6 Bq/ m' (Table 1), then the maximum contribution of "Chernobyl's" Cs'" could not have been more than 6%. The results of the vertical distribution of Cs'" in the Chukchi and Bering Seas and the Gulf of Anadyr are given in Figs. 1, 2, and 3. The concentration of Cs'", which is the average value along the whole investigated area, was estimated as 2.4 Bq/m- (a range of 1.6 to 3.7 Bq/m- ), 2.4 Bq/m- for the Chukchi Sea and the Gulf of Anadyr, and 2.3 Bq/m^ for the Bering Sea. The maximum concentration, 3.7 Bq/m\ was determined in the 0 to 40 m layer to the southwest of St. Lawrence Island. Fig. 1. Vertical profiles of Cs'" concentrations in the Chukchi Sea (the mean direction of the currents are shown hy the arrows). Numerator = Cs'" budget (Bij/m-), denominator = the average concentration of Cs'" (Bq/m') at that station from the surface to the bottom. It is important to note that the vertical distribution of Cs'" in the Bering Sea was homogeneous. The vertical distribution in the Chukchi Sea, however, was characterized by an elevated concentration in the bottom layers (ranging from 2.5 to 5.5 Bq/m' and an overall average of 3.1 Bq/m'). The maximum gradients for vertical distribution were observed in the western Chukchi Sea — that is, 1 . 1 Bq/m' in the surface layer (0-3 m) and 3.5 Bq/m' at a depth of 40 m. Simultaneously, a correlation in spatial distribution of Cs'" and salinity was observed such that in a direction from the west to the east there was a decrease in the vertical gradients of these parameters and an increase of Cs'" concentrations with an increase in salinity in the upper layers. Fig. 2. Vertical profiles of Cs'" concentrations in the Northern Bering Sea. Fig. 3. Vertical profiles of Cs'" concentrations in the Gulf of Anadyr. Obviously, the flow of surface waters from the west into the Chukchi Sea significantly influenced the distribution of Cs'", especially in the western part of the Chukchi. The observed homogeneity of the Cs'" over these areas demonstrated the lack of local inputs of this material. The concentration level was typical for the world oceans and was indicative of global input of Cs'" from the atmosphere over a long period of time. 328 We calculated a concentration budget for Cs'", using its vertical distribution in different areas (Figs. 1,2,3). For the period from the beginning of nuclear exercises and extending up to 1978, the total input of Cs'" on the Earth's surface was estimated as 1,740 and 1,150 Bq/m' for the latitudes 60-70°N and 70-80°N, respectively (Vakulovsky etui. 1985). Accounting for radioactive disintegration, the concentration of Cs'" could decrease by no less than twice; therefore, the maximum estimated amount of Cs'" on the Earth's surface in the above-mentioned areas should not exceed 1,370 and 575 Bq/m- . Amounts of Cs'" in the seawater, calculated on the basis ofthis investigation, are 2 10 Bq/m"forthe Gulf of Anadyr and 120 Bq/m' for the Chukchi Sea and the northern Bering Sea. The average concentrations of Cs' " in the Chukchi and the Bering Seas are 10-50 times lower than in the Black Sea (Buesseler. 1987; Nikitin et al. 1988) and in the Barents, the Greenland, and the Kara Seas, where local sources of radioactive pollution are situated. 329 Subchapter 8.5: Distribution of Organic Matter 8.5.1 Characterization of Sediment Organic Matter RICHARD S. SCALAN' , E. WILLIAM BEHRENS*. MICHAEL E. CAUGHEY*, RICHARD K. ANDERSON*, and PATRICK L. PARKER' 'Universin- of Texas. Marine Science Institute. Port Aransas. Texas, USA ''University of Texas, Institute for Geophysics. Austin. Te.xas. USA * Aquatic Chemistry Section. Illinois State Water Sun'ey. Champaign. Illinois. USA "Coastal Science Laboratories. Inc.. Austin. Texas, USA Introduction Carbon isotopic compositions are effective indicators of the source of sedimentary organic matter (Craig, 1953). For example, Sackett and Thompson (1963). Hunt (1970), and Hedges and Parker ( 1 976) used stable carbon isotopes as a tracer of the incursion of terrestrial organic matter into the estuaries bordering the Gulf of Mexico and the Atlantic Ocean. A depletion in carbon of the heavier isotope ("C) is generally associated with terrestrially derived organic matter, while an enrichment suggests incorporation of marine derived material (Fry & Sherr, 1984). Nitrogen isotope variations are less associated with the environment of their origin (Sweeney & Kaplan, 1980) but rather reflect the trophic level from which the organic matter has been derived (Miyake & Wada, 1967; Wada & Hattori, 1976;Mackof?fl/., 1982; Minigawa& Wada, 1986). Primary producers of organic nitrogen are isotopically like their source, atmospheric nitrogen, while consumers of organic matter become enriched in the heavier isotope ( '^N) with each step up the trophic ladder. The isotopic composition of nitrogen incorporated into marine sediments may indicate not only the trophic shift but also the degree of cycling and recycling of the organic matter in the water column and in the sediments. Remineralization of organic nitrogen may not be accompanied by significant isotopic fractionation; however, many reactions of nitrogenous compounds in natural and cultured systems may lead to considerable nitrogen isotope fractionation (Cifuentes elal.. 1988;Hochf/a/., 1989). Carbon and nitrogen elemental content, and more specifically the C/N ratio, are also useful for indicating the sources of organic matter. Terrestrial plants with high carbon to nitrogen ratios are contrasted with marine organisms rich in organic nitrogen. The relative contributions of these two sources can be estimated by their C/N ratios (Fagancli et al.. 1988). Of course, the picture is complicated in nature because there are more than two end members in most ecologic systems. This report summarizes the results and conclusions of a four year effort to study the isotopic and elemental distribution of organic carbon and nitrogen of sediments within the Chukchi- Bering-Anadyr system. Included in the repertoire of samples are those recovered in the Third Joint US-USSR Bering & Chukchi Seas Expedition in August 1988. The present distribution of carbon and nitrogen throughout the arctic marine ecosystem can result from several well known but, perhaps, inadequately studied processes; 7. primary production through fixing atmospheric carbon dioxide and nitrogen by phytoplankton; 2. transport of nutrients into the system from upwelling of deep Pacific waters; i. transportation of primary production of terrestrial origin by rivers and streams; and 4. recycling of the.se elements by remineralization of organic matter both in the sediments and in the water column. In this report we are primarily concerned with the sources and sinks of these elements within the sediments. Methods Sediment samples were collected on eight different cruises from 487 stations at approximately 280 separate locations. Table 1 lists the cruise identifications, dates, and number of samples, plus replicates of sediments taken for each cruise. Sample station locations are shown on the map of Fig. 1. Because of strong bottom currents, some samples (particularly those recovered from the area of Anadyr Strait west of St. Lawrence Island) were mainly cobbles and boulders with very little fine-grained sediments at the surface. Samples from this locale are largely muds that were found adhering to cobbles or the van Veen grab. Samples were frozen at the lime of collection and maintained frozen until prepared for analysis in the laboratory. Samples were thawed, acidified, diluted, and picked free of any visible macro-organic materials such as worms, amphipods, hydroids, bivalves, etc. The residues were filtered, washed, air-dried at 60°C, and very gently disaggregated by passing through a screen of opening size equal to 150 |i meter. Any material not passing this mesh was discarded. TTie nitrogen isotope measurements were made on a Nuclide model RMS-6 mass spectrometer. For carbon isotopes a VG Micromass model 602-E instrument was used. The data are expressed by the conventional del notation: "("C/'-C), [("C/'-O 1 ("C/'=C)„„ J 10' «/,. ("C/'=C)„„ as the parts per thousand difference in the isotope ratio of the sample and an arbitrary standard, the carbon dioxide generated from the PeedeeBelemnite (Craig, 1957). Asimilarexpression, 333 TABLE 1 Cruises on which sediment samples were collected. Cruise Vessel Dates Number of ID samples HX-72 a- Helix 12-23 July 1985 96 HX-74 a- Helix 27 August-10 September 1985 29 HX-84 a- Helix 30 June- 10 July 1986 33 HX-85 a- Helix 11-26 July 1986 25 HX-88 a - Helix 24 August-9 September 1986 74 '1'1-213 T.G. Thompson 20 July-10 August 1987 61 TT-222 T.G. Thompson 2-25 July 1988 59 AK-47 Akademik Korolev 26 July-24 August 1988 110 Chukchi Sea « - Akademik Korolev Cruise o - ISHTAR Cruises oo CD CD 59 Fig. 1 . Location of stations from which sediment samples were recovered. 5"N, is used for "N/"'N data where atmospheric nitrogen is taken as the standard. Based on repeated analysis of samples and standards, the 5" C values have an error of less than 0. 1 per mil C'/,,,, ) and 5''^ N of less than 0.3 per mil. Sealed tube oxidations were used to prepare CO, suitable for isotopic analysis (adapted from Sofer, 1980). A sealed tube reduction of organic nitrogen (adapted from Macko, 1 98 1 ) in Pyrex tubes at 590°C combined with a postreduction purification, provided Nt suitable for nitrogen isotope analysis. Carbon and nitrogen elemental compositions of the dried sediments were measured using a Perkin-ElnierCHN- Analyzer, model 240 B. Sufficient numbers of blanks, standards, and replicated samples were determined to allow an estimated standard deviation of ±2% of the amount present. Perhaps one of the more readily assimilated means of representing large amounts of data is by contour plotting on a map of the study area. While an attempt has been made to be completely objective in the selection of contour lines, some subjectivity is probably inherent in the "canned" computer program used in these presentations ("SURFER Ver. 4, 1989," Golden Software, Inc.). Results and Discussion Because only the clay-silt fraction size was used for analysis, the C and N quantitative data do not represent values for the total sediment and thus cannot be used as direct indicators of total sediment organic carbon or nitrogen. This organic fraction probably represents, for the most part, material added to the sediments either directly or through incorporation into fecal pellets and other small particles. It includes material reworked or produced by bacterial or other nano-organisms. By restricting the analysate to the fine-grained fraction, it was hoped that the carbon and nitrogen analyzed would represent an integrated value uninfluenced by inclusion of even a small quantity of macro-organisms. Results of isotopic and elemental analyses of the sediments are summarized in Table 2 and are incorporated into graphical representations in the isopleths for 5" C, 5'^ N. weight percent C, weight percent N, and C/N ratios of Figs. 2 through 6. Although not all of the samples collected have been analyzed and results for some stations are incomplete, all of the contour 334 TABLE 2 Attribute Summary of Analyses of Sediment Samples 5" C 5" N C/N Average Std. Dev. (± 1 ) No. of Samples Maximum Value Minimum Value 21.5 0.88 8.0 0.12 8.66 1.24 0.52 2.27 0.07 2.39 234 299 167 299 299 16.0 4.30 19.4 0.43 38.2 27.3 0.12 0.2 0.0008 2.4 figures show a common trait for the measured parameters; viz., organic matter generated or deposited in the sediments of the eastern part of the study area is readily distinguished from that of the western part. Carbon In Fig. 2, six general locations show enrichment in organic carbon: southern Bering Sea, central and northern Gulf of Anadyr, western Anadyr Strait, just north of the Bering Strait, and western Chukchi Sea. Though other parts of the study area are less organic-rich than these "hot spots," the entire Bering- Chukchi locale is abundant in carbon comparable to many other shelf environments. The average (0.88, Table 2), for instance, is not unlike that found for the Gulf of Mexico and other shelf environments of the world (Plucker, 1970; Newman etal., 1973; Gearing ef«/., 1977). The distribution of the carbon isotope values (Fig. 3) shows lighter (more negative) values east and north of St. Lawrence Island as compared with those of the southern Bering Sea, Gulf of Anadyr, or the western Chukchi Sea Presumably there is a considerable contribution of terrestrial organic carbon from the Kvichak, Kuskokwim, and Yukon Rivers and other minor drainage systems of Alaska. No such sources are apparent in the western part of the study area due to drainage from the Chukchi Peninsula. The del 1 3-C values grade "lighter" away from the Yukon River toward the Seward Peninsula, suggesting either greater deposition of the terrestrially derived organic matter at some distance from the river delta (Dean, 1986, personal communication ) or a contribution from the Seward Peninsula, perhaps from older mining operations on shore or more recent pollution from anthropogenic sources at Nome, Alaska. Values of the Gulf of Anadyr and the western Chukchi Sea resemble those of the open ocean. They show no contribution of terrestrial organic matter from the Chukchi Peninsula or from the Anadyr River. Nitrogen Del 1 5-N values of the sediment fines are shown graphically in Fig. 4. Values of 8 to 9 per mil are common throughout the study area. They become somewhat lighter in the Gulf of Anadyr (7 per mil) in the southern Bering Sea (4.5 per mil) and in the eastern Chukchi Sea (4.5 per mil). Three isotopic "lows" Chukchi Sea Fig. 2. Areal dislribulion of carbon concenlrations in sediments. occur at the biological "hot spots" north of St. Lawrence Island and two locations just north of the Bering Strait in the central Chukchi Sea. An isotopic "high" is associated with the output of the Yukon River. Organic nitrogen content of sediment fines, shown in Fig. 5, is fairly consistent with the organic carbon content. Figure 6 shows the relationship between the two components. The relatively high cortelation is not unusual and merely reflects the similarities of all biological tissues. The scatter about the regression line illustrates the relative variations of the C/N ratios. The slope of the regression line in Fig. 6 corresponds 335 Chukchi Sea Gulf of 'V Anadyr J 7^ i-S?/' -^■21 ----. J L Fig. 3. Areal distribution of carbon isotope values of sediments. Chukchi Sea f^ (D w Fig. 5. Areal distribution of nitrogen concentrations in sediments. Chukchi Sea J \ \ L CO CO Fig. 4. Areal distribution of nitrogen isotope values of sediments. 0.0 0.1 0.2 0.3 0.4 Nitrogen (% by weight) Fig. 6. Relationship between carbon and nitrogen concentrations in sediments. 336 to a C/N ratio (at/at) of 7.7, slightly higher than the commonly accepted "Redfield Ratio" of 6.6 for marine organic matter (Froelich era/., 1979). Mostlikely,thisindicatesacontribution of terrestrially derived organic matter to these sediments. There is a possibility that recycling of sedimentary organic matter could lead to a selective reduction in nitrogen content, thus raising the C/N ratio. The distributions of C/N ratios in sediment tmes of the study area are shown in Fig. 7. A strong influence of the contribution of terrestrial organic matter is readily apparent at the mouth of the Yukon River. This is the same relationship as observed for the carbon isotopic composition distribution. Thus, much of the organic matter in these sediments must be derived from terrestrial sources transported to the Bering Sea by the Yukon River. The relationship between the two parameters is shown in Fig. 8. There is a complete overlap of samples from the area of the mouth of the Yukon River and Norton Sound with those from the rest of the study area. All of the samples having 5"C<-24 per mil or C/N ratio >1 1 are from the Yukon area. Figure 9 shows isopleths of a devised "environment of deposition" parameter formed from the normalized (0.0 to 1 .0), unweighted product of (5"C and the C/N ratio values used for Figs. 3 and 7, respectively. Both of these parameters are dependent, at least in part, on their terrestrial organic contribution. Thus, their product would tend to emphasize this m Q Q. -18 -20 -22 : -24 - -26 -28 • = Yukon Area - y 0 = Other Areas • D •X'" • - 0 ^y • - 4» • 1 1 1 1 1 1 1 1 1 13 15 17 C/N Ratio Fig. 8. Relationship between carbon isotope values and C/N ratios for sediments. Chukchi Sea Fig. 7. Areal distribution of C/N ratios in sediments. Fig. 9. Contours of a relative parameter of "environment of origin" of sediment organic matter. 337 aspect lid minimize the influence of those samples for which one or the other value was more influenced by a factor other than the environment of origin. The influence of Yukon derived organic matter is quite evident. A similarly derived parameter is shown by the isopleths of Fig. 10. In this case, contours of a normalized unweighted product of the carbon and nitrogen elemental content of Figs. 2 and 5 are plotted. Such a parameter would only tend to emphasize locations of concentrations of sediment organic matter in the fine-grained fraction (not biomass ). Organic "hot spots" are evident in the southern Bering Sea, the Anadyr River, the Gulf of Anadyr, Anadyr Strait, Bering Strait, and the western Chukchi Sea. No excessive sediment organic concentrations are apparent at the Yukon River Delta nor at the site of high biological activity reported by Grebmeier and McRoy (1989) northeast of St. Lawrence Island. Support for this study was provided, in part, by the ISHTAR project of the National Science Foundation (DPP-8405286, DPP-8605659) and by The University of Texas at Austin, Marine Science Institute. A major contnbution to the overall sediment study was the participation of one of us (E.W.B.) in the Third Joint US- USSR Bering & Chukchi Seas Expedition aboard the Soviet research vessel Akademik Korolev. We express appreciation to the USSR State Committee for Hydrometeorology and the US Fish and Wildlife Service, USA, who made this sampling effort and our participation possible. Chukchi Sea Fig. 10. Contours of a relative concentration parameter of sediment organic matter. 338 Subchapter 8.6: Abiotic Processes of Decomposition of Some Organic Contaminants 8.6.1 Solar Oxidation of Benzo(a)pyrene NATALYA I. IRHA, EHA R. URBAS. and UVE E. KIRSO Institute of Chemistry, Estonian Academy of Sciences. Tallinn. USSR Introduction The extent of photochemical processes and their contribution to self-purification of the marine environment from carcinogenic PAH's are determined by both the value and distribution of solar irradiation energy (Rabek, 1985; Mill etal.. 198 1 ) and the level of pollution of seawater, as well as the concentration and composition of pollutants. The latter may have an intluence upon the pattern and intensity of the degradation processes of PAH's (Kirso & Gubergrits, 1971; Gubergrits et al.. 1975). Although systematic studies have been carried out on the photooxidation of individual PAH's in water (Kirso & Gubergrits, 1971; Gubergrits et al., 1975; Paalme et al.. 1976. 1983b), there are few data on these processes under natural conditions. Therefore, during the cruise of the RA' Akademik Korolev (July-November 1988) a study was undertaken on the kinetics of the oxidative photolysis of a typical carcinogenic PAH — benzo(a)pyrene [BaP] (Car, 1971) in the Bering Sea (Table 1 ). It is known that the Bering Sea is almost wholly in the subarctic zone, excluding its northern parts, which are in the arctic temperature zones (Izrael & Tsyban, 1987). The main body of its waters is characterized by a subarctic structure whose specific feature is the existence of cold and warm intermediate layers. The upper layer thickness average 25-50 m, the salinity being 32.8-33.4 and the temperature about 5 to 7°C. According to Izrael and Tsyban ( 1 987), PAH' s are permanent and typical components of these ecosystems. Taking into account the low influence of this area from human activities, the physicochemical parameters of the atmosphere above these waters, and characteristics of the surface water layer, a study of sunlight photolysis of PAH's in seawater at lower temperatures and low intensity of solar irradiation was of interest. Methods and Materials Detailed descriptions of the techniques used in carrying out these experiments are described in Subchapter 2.6 of Residts of the First Joint US-USSR Central Pacific E.xpedition (BERPAC). Autumn 19H8 (Nagel, 1992). Experimental conditions are described in Table 1. Results and Discussion From kinetic data (Table 2; Figs. 1 , 2) it follows that during the first hour of exposure, a decrease in the BaP concentrations in seawater is described by a fonnal-kinetic equation for the first-order reaction, where c,, and c, are the initial BaP concentration at zero time, and that at a certain time t, k is the constant of the first-order reaction, the dimensions for this constant are per second (s '). TABLE 1 Exposure of BaP solution in seawater (the 47th cruise of the RJM Akademik Korolev] Month Experiment Coordinates Water Temp. Average dose of solar (1988) Number t = °C radiation Q MJ/m- during the first 3 hours August 53°58'N/176°28'W 53°58'N/176°28'W 14.1 15.7 1.48 1.09 341 TABLE 2 Kinetic characteristics of photochemical transformation of BaP in sea water under solar irradiation in the Bering Sea (47th cruise of the RA^ Akademik Korolev, July-November 1988) Experiment Initial Rate constant Number of Correlation Sterility No. (see BaP 10-V'(k±) data points coefficient of media Table 1 ) concentration r (first-order) 1 1.47 1.69 ±0.13 5 0.99 _ 2 4.20 1.60 ±0.08 7 0.99 + 4.44 1.20 ± 0.16 6 0.97 ~ C/Co 2 c o C/Co p 0 c o ■^0.5 c o c o o CO O ^0 a '- ^ a t ,hour 0 4 t ,hour Fig, 1 . Kinetics of BaP degradation under sunlight iiradition on the surface of the Bering Sea (coordinates; 67°42' N/l l.'i°4.^' W): a) in sterilized sea water; b) in sea water; and c) by autooxidation. Fig. 2. Kinetics of BaP degradation under sunlight Irraditlon on the surface of the Bering Sea (coordinates: 53'58' N/175°28' W): a) in sterilized sea water; b) in sea water; and c) by autooxidation. 342 8.6.2 Influence of Ultraviolet Radiation on the FateofPCB's SERGEI M. CHERNYAK Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow. USSR Introduction Chloroorganic compounds are considered to be the most environmentally resistent of organic compounds. The only abiotic process resulting in PCB destruction is photochemical decomposition (Brown et al.. 1984), which leads to dechlorination of the higher halogenated molecules. Studies on the photochemical degradation of PCB"s showed that the most active destruction of PCB" s at low concentrations occurs at the level of 1 ng/1 and that the PCB half-life values were about 1 to 2 years, depending on solar radiation rates (Bunce etai. 1978) It is important to note that PCB transformation by sunlight occurs both as a result of direct light absorption by these compounds and also due to the interaction between reagents formed by the sunlight and subsequent reaction with the PCB molecules — for example, by irradiation of an organic solute that the PCB's might be associated with (Van Noort et al., 1988). New data on photochemical PCB decomposition processes were obtained during the Third Joint US-USSR Bering & Chukchi Seas Expedition on board the research vesselAkademik Korolev in 1988. Materials and Methods In order to make an assessment of the impact of photochemical processes on the behavior of chlorinated hydrocarbons in marine ecosystems, scale-model experiments on the decomposition of standard Aroclor 1232 were carried out in the aquatic environment of the Chukchi Sea and the Bering Sea by exposing this Aroclor to natural sunlight. The experiments were conducted in 5-1 reactors with a surface area of 400 cm-. The side walls of the reactors were screened with dark foil. The Aroclor 1232 mixture was added in acetone to give a concentration of 100 ng/1 in the sterilized seawater that was placed in the reactors. Control flasks were prepared identically and screened from the sunlight. Every hour, three 0.5-1 samples were removed from each reactor. The samples were extracted by shaking with n-hexane (twice with 50 ml). The extracts were concentrated using a rotary evaporator to a volume of 2 ml, whereupon they were purified by shaking them with concentrated sulfuric acid. Tests for PCB microbial decomposition were carried out at the same time as the photochemical tests and under similar conditions. These results are described in Subchapter 4.4 of this volume. The PCB content in the solutions was determined using a Hewlett-Packard model 5840A gas chromatograph. The chromatography conditions were as follows: a 30-m fused quartz capillary column with an internal diameter of 0.32 mm and coated with a0.25-m layer of DB- 1 chromatography phase. The analysis was carried out using column thermostat temperature programming as follows; the initial temperature was 120°C. and the temperature was raised at 5°C/min up to 250°C and held there for 14 min; thus, the chromatography time was 40 min. The injector temperature was 225°C, the electron capture detector temperature was 300°C. Results and Discussion Table 1 shows the findings of the photochemical PCB decomposition in Bering Sea water. The data demonstrates that after 6 h of exposure, up to 50% of 2,2',3,4-tetrachlorobiphenyl component (BZ# 4 1 - Ballschmitter & Zell, 1980) and 30 to 40% of certain tri- and tetrachlorobiphenyls were decomposed. In the microbial tests, however, 75% of the added 2,2',3,4-tetrachlorobiphenyl and up to 50-60% of some of the low-chlorinated components underwent a reaction of oxidation in 12 h (Fig. 1). In the photolysis tests, only seven components of pentachlorobiphenyls exhibited some minor degradation. Hexachlorobiphenyls and higher-chlorinated compounds did not undergo any reaction under the experimental conditions. Therefore, only 16 main components of the Aroclor 1232 technical mixture were significantly altered in the photochemical degradation tests. The experimental data showed that in the seawater under the influence of photochemical PCB degradation, only direct dechlorination proceeded, and this was accompanied by isomerization and condensation. The rate of the reaction appeared to depend more on the molecular configuration than the numberof chlorine substituents. The availability of chlorine atoms in locations 2,2' or 4,4' of biphenyl molecules appears to be a necessary requirement for PCB's to undergo a reaction of photochemical degradation. Schematically, the process of photochemical PCB degradation ( hexachlorobipheny 1 ) in seawater can be shown in the schematic (Fig. 2) As the reaction scheme demonstrates, the photochemical PCB degradation in the seawater proceeds in a very regular pattern. Direct dechlorination takes place without the rupture of the bonds between the benzene rings and without biphenyl 343 TABLE 1 Photochemical degradation of different PCB components in sea water. Time of Exposure BZ' CI No. Position Ih 2h 3h 4h 5h 6h 7h 8h 9h lOh llh 12h 13h I4h 15h 16h 5d lOd 15d 20d PCB Decomposed as Percent of Total Added (%) 7 2,4 1 5 8 10 12 14 16 17 17 18 18 19 20 20 20 20 21 21 T2 23 16 2,2',3 3 8 11 13 16 18 19 21 ->-> 23 24 24 25 26 27 27 31 31 32 32 52 2,2',5,5' 1 3 5 6 8 10 12 13 15 17 19 22 24 27 28 29 29 31 31 31 49 2,2',4,5' 6 9 13 16 18 20 22 23 24 26 27 27 28 28 28 29 30 30 30 30 42 2.2',3.4' 7 12 16 18 21 23 25 27 28 29 30 31 32 33 34 35 40 41 41 41 47 2,2',4,4' 4 7 9 10 11 11 12 12 13 13 14 14 15 15 16 16 19 20 20 20 84 2,2'.3,3'.6 4 6 8 9 10 10 10 10 II 11 II 12 12 12 13 13 14 14 14 14 119 2,3'.4.4',6 2 5 6 7 8 8 9 9 9 10 10 10 10 11 11 11 15 15 15 15 36 3,3',5 3 4 6 7 8 8 9 9 9 10 10 10 10 11 11 11 11 11 11 II 91 2,2',3,4',6 3 3 5 6 6 7 7 7 8 8 8 8 9 9 9 9 9 9 9 9 102 2,2',4,5,6' 2 3 5 5 5 5 6 6 6 7 7 7 7 8 8 8 8 8 8 8 70 2,3'.4',5 2 3 3 3 4 4 4 5 5 6 6 6 7 7 7 7 7 7 7 7 66 2.3'.4,4' 2 2 3 3 4 4 4 5 5 5 6 6 7 7 7 7 7 7 7 7 85 2.2',3.4.4' 2 2 T 3 3 4 4 4 5 5 5 6 6 7 7 7 7 7 7 7 90 2,2',3,4',5 2 2 3 3 3 3 4 4 4 4 5 5 5 6 6 6 6 6 6 6 99 2,2\4,4',5 2 2 3 3 3 3 4 4 4 4 5 5 5 5 5 6 6 6 6 6 'Numbering corresponds to the convention of Ballschmitter and Zell ( 1 980). h = hours d = days c " o c b ° o ^-' B o O 10 Exposure time. 15 21 davs Fig. 1. Decomposition of PCB (Dichlorobiphenyls) under microbial and Photochemical transformation. Bering Sea. 53°58' N, I75°28' W. microbial decomposition photochemical decomposition pholochemical dccompostiton in presence if PAH. Structure decay. These reactions are accompanied by isomerization condensation processes, resulting in the fonnation of terphenols, tetraphenyls, and dibenzofurans (Bunce et ai, 1 978 ). These dechlorination products are now more susceptible to subsequent microbial degradation. When comparing the data on the scale-model experiments on photochemical breakdown with microbial PCB degradation in the seawater, it was determined that many of the PCB congeners that underwent photochemical degradation were not the ones undergoing decay from exposure to microflora. Of all the components of the technical Aroclor 1232 product, only 2,3"4,4'-tetrachlorobiphenyI and 2,3'.4'.5-tetrachlorobiphenyl responded to both microbial and photochemical degradation. However, the rate of photochemical reactions is 10 to 15 times slower than the rate of microbial degradation (see Subchapter 4.4 of this volume). It was also determined that othercontaminants (for example, PAH's) inhibited the photochemical degradation of PCB's by 10%. Furthermore, it was found that PCB's were inhibitory toward the photochemical oxidation of benzo(a)pyrene by 20% (Fig. 3 ). (These experiments were carried out jointly with N. Irha and E. Urbas from the Estonian Academy of Sciences and the final results will be published in the future.) Therefore, the processes of photochemical PCB degradation were studied for the first time in the marine environment in the arctic regions of the oceans during the Third Joint US-USSR Bering & Chukchi Seas Expedition. The data allowed definition of photochemical PCB oxidation in seawater, and gave a quantitative assessment of this process, which is very important to know when studying biochemical cycles and predicting ecological situations in marine ecosystems. 344 Cl- Cl CI ^& CI CI CI — <^:^e, CI CI CI CI Fig. 2. Schematic representation of the photochemical degradation of PCBthexachlorobenzene) according to Bunce el al. ( 1978). ioo*-p Oh cd CQ t+- O c o .2 C3 t-H C D O C o U o P 15 e 50 — r -^^ ■• i \ o 0 Q ■^Q O ■-D- 0 1 o -D-. t, hours Fig. 3. Change of the benzo(a)pyrene in time a) with addition; b) without addition of PCB in .sterilized sea-water; and c) by autooxidation with sunlight irradiation on the surface of the Bering Sea, 5.V58' N, 175"28' W. 345 Chapter 8 References Andersson, O., Linder, C. E.. Olsson, M., Reutergardh. L., Uvemo, U. B. & Wideqvist. U. ( 1988). Spatial differences and temporal trends of organochlorine compounds in biota from the Northern Hemisphere. Arch. Environ. Contcim. To.xicol. 17, 755-765. Anikejev, V. B. & Urbanovitch, M. J. ( 1989). Distribution of organic environmental pollutant in the surface microlayer- water system in some regions of world oceans. Geokhimiia, Nauka Publishers, Leningrad, pp. 738-744. (in Russian) Atlas, E. & Giam, C. S. (1986). Sea-air exchange of high- molecular weight synthetic organic compounds. In The Role of Air-Sea Exchange in Geochemical Cycling (P. Buat- Menard, ed.), D. Reidel, Dordrechtl, Holland. Atlas, E. & Giam, C. S. (1989). Sea-air exchange of high molecular weight synthetic organic compounds — Results from the SEAREX Program. In Chemical Oceanography (J. P. Riley. R. Chester & R. A. Duce, eds.), 10, 337-378. Academic Press, New York. Ballschmitter, K. & Zell, M. ( 1 980). Analysis of polychlorinated biphenyls by capillary gas chromatography. Freseniiis Z. Anal.lChem. 302.20-31. Bidleman, T. F. (1988). Atmospheric processes: Wet and dry deposition of organic compounds are controlled by their vapor-particle partitioning. Environ. Sci. Technol. 22, 361-367. Bidleman T. F., Patton, G. W., Walla, M. D., Hargrave, B. T., Vass, W. P.. Erickson, P., Fowler, B., Scott, V. & Gregor. D. J. (1989). Supply of toxaphene to Arctic Ocean fauna by atmospheric transport. Arctic 42, 307-3 13. Bidleman, T. F., Wideqvist, U., Jansson, B. & Soderlund, R. (1987). Organochlorine pesticides and polychlorinated biphenyls in the atmosphere of southern Sweden. Atmos. Environ. 21,641-654. Billings, W. N. & Bidleman, T. F. (1980). Field comparisons of polyurethane foam and tenax-GC resin for high volume air sampling of chlorinated hydrocarbons. Environ. Sci. Technol. 14, 679-683. Billings, W. N. & Bidleman, T. F. (1983). High volume collection of chlorinated hydrocarbons in urban air using three solid adsorbents. Atmos. Environ. 17, 383-391. Bletchly,J.D.( 1984). Polychlorinated biphenyls: Production, current use and possible rates of future disposal in OECD countries. In Proceedings ofPCB Seminar, (M. C. Barros, ed.). Ministry of Housing, Physical Planning and Environment, the Netherlands, pp. 343-372. Blummer, M. & Yongbloom, W. (1975). Polycyclic aromatic hydrocarbons in soil and recent sediments. Science 188(4183), 53-55. Bockris, J. O & Oh, J. M. (eds.) (1982). Environmental Chemistry. Khimija Publishers, Moscow, 670 pp. ( in Russian ) Bourcart, I., Lalou, G. & Mallet, L. ( 1961 ). About the present BaP-type hydrocarbons in the coastal muds and the beach sands along the coast of Ville France. C. R. Acad. Sci. , Paris. 252, 640-644. Brooks, J. M., Kennicutt, M. C, II & Carey, B. C. (1986). Strategies in offshore surface geochemical exploration. Oil and Gas Journal 84, 66-72. Brown, J. F., Bedard, D. L., Brenman, M. J., Camahan, J. C, Feng, H. & Wagner, R. E. (1987). Polychlorinated biphenyl dechlorination in aquatic sediments. Science 236(4802), 709-712. Buesseler, K. O. ( 1987). Chernobyl: Oceanographic studies in the Black Sea. Oceanus 30(3), 23-31. (in Russian) Bunce. N. J., Kumar, Y. & Brownlee, B. G. (1978). An assessment of the impact of solar degradation of PCB's in the aquatic environment. Chemospherel(2), 155-164. Burkhardt. L. P., Arm.strong, D. E. & Andren, A. W. (1985). Henry's Law constants for the polychlorinated biphenyls. Environ. Sci. Technol. 19, 590-596. Cifuentes, L. A., Sharp, J. H. & Fogel, M. L. (1988). Stable carbon and nitrogen isotope biogeochemistry in the Delaware Estuary. Limnol. Oceanogr. 33, 1 102-1 1 15. Clar, E. (1971). Polycyclic Hydrocarbons. Vol.2. Academic Press. London. Clark, A. & Low, R. ( 1 98 1 ). Aliphatic hydrocarbons in benthic invertebrates from two sites in Antarctica. Mar. Pollut. Bidl. 12(1), 10-14. Coachman. L. K. & Aagaard, K. ( 1988). Transports through Bering Strait: Annual and interannual variability. J. Ceophys. Res. 92,, 15535-15539. Comer, E. (1975). The fate of fossil fuel hydrocarbons in marine animals. Proc. R. Soc. Lond. 189. 1096-1 109. Craig, H. (1953). The geochemistry of the stable carbon isotopes. Geochim. Cosmochim. Acta 3, 53-92. Craig, H. ( 1957). Isotopic standards for carbon and oxygen and correction factors for mass-spectrometric analysis of carbon dioxide. Geochim. Cosmochim. Acta 12, 133-149. Cromartie, E. W., Reichel, W. L., Locke, L. N., Belisle, A. A, Kaiser, T. E., Lamont, T. G., Mulhem. B. M., Prouty, R. M. & Swineford, D. M. (1975). Residues of organochlorine pesticides and polychlorinated biphenyls and autopsy data for bald eagles, 1971-72. Pe.ftic. Monit. J. 9, 1 1-14. Dean, K. G. (1986). Model of the distribution of near-surface turbid water discharged from the Yukon River. ISHTAR Conference, New Orleans, Louisana. Eisler. R. (1985). Cadmium hazards to fish, wildlife, and invertebrates: A synoptic review. US Fish Wildl. Serv., Biol. Rep.85(l.2). Eisler, R. (1988). Arsenic hazards to fish, wildlife, and invertebrates; A synoptic review. US Fish Wildl. Serv., Biological Report 85( 1.12). Ellington. J. J.. Standi. F. E., Jr., Payne, W. D. & Trusty, C. (1987). Measurement of hydrolysis rate constants for evaluation of hazardous waste land disposal. Vol. 2. EPA 600/3-87/019. EPA (1980a). Environmental Protection Agency, ambient water quality criteria for cexachlorocyclohexane. EPA 440/5-80-054. 347 EPA (1980b). Environmental Protection Agency, lindane position document 2/3. EPA 540/9-87-153. EPA (1985). Environmental Protection Agency, guidance for the reregistration of pesticide products containing lindane as the active ingredient, 286 pp. EPA RS-85-027. Faganeli J., Malej, A., Pezdic, J. & Malacic, V. ( 1988). C:N:P ratios and stable C isotopic ratios as indicators of sources of organic matter in the Gulf of Trieste (Northern Adriatic). Oceanol. Acta 11, 377-382. FAO (1985). Food and .Agricultural Organization of the United Nations, Prod. Yearb., Vol. 39, Rome. FAO (1987). Food and Agricultural Organization of the United Nations, Prod. Yearb.. Vol. 41, Rome. Fedoseyeva, G. E., & Khesina, A. Ya. ( 1 968 ). Use of quasilinear luminescence spectra for qualitative determination of series of PAH'S. / Applied Spectroscopy 10(2), 282-288. (in Russian) Flegal, A. R. (1985). Lead in a pelagic food chain. In Heavy Metals ill Water Organisms (J. Salanki, ed.), pp. 83-90, Symposia Biolgica Hungarica, Vol. 29. Akacemiai Kiado, Budapest, Hungary. Florence, T. ( 1 983 ). Trace elements speciation and toxicology. Trends in Analytical Chemistry 2(7), 162-166. Froelich, P. N., Klinkhammer, G. P., Bender, M. L., Leudtke. N. A., Heath, G. R., Cullen, D., Dauphin, P., Hammond, D., Hartman. B. & Maynard, V. (1979). Early oxidation of organic matter in pelagic sediments of the eastern equatorial Atlantic: Suboxic diagenesis. Geochim. Cosmochim. Acta 43, 1075-1090. Fry, B. & Sherr, E. B. (1984). 5"C measurements as indicators ofcarbon flow in marine and freshwaterecosystems. Contrib. Mar. Sci. 27, 13-47. Garrett, W. G. ( 1965). Collection of slick-forming material from the sea surface. Limnol. Oceanogr. 10, 602-605. Gearing, P. J., Plucker, F. E. & Parker, P. L. ( 1977). Organic carbon stable isotope ratios of continental margin sediments. Mar. Chem. 5,251-266. Goldberg, E.( 1975). Synthetic organohalides in the sea. Proc. J. Soc. Land. Ser. B. 189, 277-289. Grebmeier, J. M. & McRoy, C. P. (1989). Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. III. Benthic food supply and carbon cycling. Mar. Ecol. Prog. Ser. 53.79-91. Gregor, D. J. & Gummer, W. D. (1989). Evidence of atmospheric transport and deposition of organochlorine pesticidesandPCB's in Canadian Arctic snow. Environ. Sci. Technol. 23,561-565. Gubergrits, M. Ya., Kirso U. E. & Paalme, L. P. (1975). Transformation of Carcinogenic Compounds in the Hydrosphere. Znanije Publishers, Moscow, (in Russian) Hargrave, B. T., Vass, W. P., Erickson, P. E. & Fowler, B. R. (1988). Atmospheric transport of organochlorines to the Arctic Ocean, Tellus 40B, 480-493. Hedges, J. I. & Parker, P. L. (1976). Land-derived organic matter in surface sediments from the Gulf of Mexico. Geochim. Cosmochim. Ada 40. 1019-1029. Hegge, D. T. (1982). Copper in surface waters of the Bering Sea. Geochimic. Cosmochim. Acta 46, 1301-1306. Hegge, D. T., Klinkhammer & Gullen, D. (1987). Manganese and copper fluxes in continental margin sediments. Geochimic. Cosmochim. Acta 51, 1059-1070. Hinckley, D. A. (1989). Vapor pressures, Henry's Law constants, and air-sea gas exchange of selected organochlorine pollutants. Ph. D. dissertation. University of South Carolina, Columbia. Hinckley, D. A. & Bidleman, T. F. (1989). Analysis of pesticides in seawater after enrichment onto Cg bonded- phase cartridges. Environ. Sci. Technol. 23, 995-1000. Hinderberger, E. J., Kaiser, M. L, & Koirtyohann, S. R. ( 1981). Furnace atomic absorption analysis of biological samples using L'vov platform and matrix modification. Atomic Spectroscopy 2( 1 ). Hoch, M. P., Kirchman, D. L. & Fogel, M. L, ( 1989). Nitrogen isotope fractionation in the uptake of ammonium by a marine bacterium. Annual Reportof the Directorof the Geophysical Laboratory. Carnegie Institute Washington. 1988-1989. Geophysical Laboratory, Washington, D.C. pp. 1 17-123. Hoff, R. M. & Chan, K. W. ( 1 986 ). Atmospheric concentrations of chlordane at Mould Bay, NWT., Canada. Chemosphere 15, 449-452. Hunt,J.M.(1970). The significance ofcarbon isotope variations in marine sediments, pp. 27-35. In Advances in Organic Geochemistry ( G. D. Hobson & G. C. Speers, eds. ), Pergamon Press, Oxford. Hunter-Smith, R. J., Balls, P. W. & Liss, P. S. ( 1983). Henry's Law constants and the air-sea exchange of various low molecular weight halocarbon gases. Tellus 35B, 170-176. Irha, N. I., Urbas, E. R. & Kirso. U. E. ( 1 992 ). The role of solar irradiation in the oxidative transformation of benzo(a)pyrene. In Results of the First Joint US-USSR Central Pacific E.xpedition (BERPAC). Fall 1988{P. A. Nagel,ed.), US Fish and Wildlife Service, Washington, D.C. Iricanin, N. & Trefry, J. H. ( 1991 ). Trace metal distribution in sediments from the Bering Sea. In Results of the Second Joint US-USSR Bering Sea E.xpedition. Summer 1984 (P. F. Roscigno,ed.),pp. 261-272. US Fish Wildl. Sen: Biol. Rep. 90(13). IRPTC (1983). International register of potentially toxic chemicals. United Nations Environment Program. Scientific Reviews of Soviet Literature on To.xicity and Hazards of Chemicals (N. F. Izmerov, ed.). Lindane, 40. Izrael, Yu. A. (1984). Ecology and Control of the State of Environment. Gidrometeoizdat Publishers, Moscow, (in Russian) Izrael, Yu. A. & Tsyban, A. V. (1981). Problems of the Monitoring of the Ocean Pollution and the Ecological Effects. Gidrometeoizdat Publishers, Leningrad, 59 pp. (in Russian) Izrael, Yu. A & Tsyban, A. V. (1985a). Ecology and problems of Worid Ocean monitoring. In Proceedings of the First International Symposium.Vo]. l,pp. 19^7. Gidrometeoizdat Publishers, Leningrad, (in Russian) Izrael, Yu. A. & Tsyban, A. V. ( 1 985b). Atmospheric transport of contaminants and their influence on the ocean and atmosphere interaction processes. In Ecological Sunry of Pollutants in the Oceans, pp. 7-24 Gidrometeoizdat Publishers, Leningrad. 348 Izrael, Yu. A. & Tsyban, A. V. (eds.)(1987). Comprehensive Analysis of the Bering Sea. Gidrometeoizdat Publishers, Leningrad, 263 pp. (in Russian) Izrael, Yu. A. & Tsyban, A. V. ( 1 989). Anthropogenic Ecology of the Ocean. Gidrometeoizdat Publishers, Leningrad, 531 pp. (in Russian) Izrael, Yu. A., Tsyban, A. V., Panov, G. A., Korsak, M. N.. Kudryatsev, V. M., Volodkovich, YuL. & Cherynak, S. M. ( 1 987). Comprehensive Analysis of the Bering Sea Ecosystem. Monitoring and Managing Environmental Impacts: American and Soviet Perspectives, pp. 58-88. Academic Press, Washington, D.C. Izrael, Yu. A., Tsyban, A. V., Panov, G. V. & Chemyak, S. M. (1990). Microbial transformation of polychlorinated biphenyls in marine polarregions. Reports of USSR Academy of Sciences (DAN USSR), 310(2), 502-506. (in Russian) Jones, D. W & Matthews, R. S. ( 1974). Carcinogenicity and structure in polycyclic hydrocarbons. Prog. Med. Chem. 180, 159-205. Kaiser, T. E., Reichel, W. L., Locke, L. N., Cromartie, E., Krynitsky, A. J., Lament, T. G., Mulhern, B. M., Prouty, R. M., Stafford, C. J. & Swineford, D. M. (1980). Organochlorine pesticides, PCB, and PES residues and necropsy data for bald eagles from 29 states — 1975-77. Pestic. Monit. J. 13, 145-149. Kawano, M.. Inoue, T., Wada, T., Hidaka, H. & Tatsukawa, R. ( 1988). Bioconcentration and residue patterns of chlordane compounds in marine animals:Invertebrates, fish, mammals, and seabirds. Environ. Sci. Technol. 11, 192-191 . Kawano, M., Matsushita. S., Inoue, T., Tanaka, H. & Tatsukawa, R. ( 1 986. ) Biological accumulation of chlordane compounds in marine organisms from the northern North Pacific and Bering Sea. Mar. Pollitt. Bull. 17, 512-516. Keizer, P. D., Gordon, D. C & Dale, J. ( 1977). Hydrocarbons in eastern Canadian marine waters determined by fluorescence spectroscopy and gas-liquid chromatography. J. Fish. Res. Board Can. 34, 347-353. Keller, C. D. & Bidleman, T. F. ( 1984). Collection of airborne polycyclic aromatic hydrocarbons and other organics with a glass-fiberfilter-polyurethane foam system. Atmos. Environ. 18, 837-845. Kennicutt, M. C, II, Brooks, J. M. & Denoux, G. J. (1988). Leakage of deep, reservoired petroleum to the near surface in the Gulf of Mexico continental slope. Mar. Chem. 24, 39-59. Kennicutt, M. C, II, Brooks, J. M. & McDonald, T. J. ( 1990). Origin of hydrocarbons in Bering Sea sediments. Part I: Aliphatic hydrocarbons and fluorescence. Org. Geochem. 17, 75-83 (submitted). Kennicutt, M. C. 11 & Comet, P. A. (1990). Resolution of sediment hydrocarbon sources: Multiparameter approaches. The John Hunt Symposium Volume (in press). Khalil, M. A. K., Rasmussen, R. A. & Hoyt, S. D. (1983). Atmospheric chloroform (CHCl,): Ocean-air exchange and global mass balance. Tellus 35B, 266-274. Kirso, U. & Gubergrits, M. (1971). Kineticsof oxidation of 3, 4-benzpyrene, phenol and 5 methylresorcinol activated by UV-irradiation. Proc. Est. Acad. Sci., Chem., Geol. 20(2), 134-139. (in Russian) Kirso, U. E., Paalm L., Kullik, E. A. & Veldre, I. A. (1985). Problems of monitoring of carcinogenic hydrocarbons in water medium. Proceedings of the First International 5>7wposium 3, 275-281 Gidrometeoizdat Publishers, Leningrad, (in Russian) Kirso, U. E., Stom, D. I., Belykh, L. I. & Irha, N. I. (1988). Decomposition ofCarcinogenic and To.xic Substances in the Hydrosphere. Valgus Publishers, Tallinn, (in Russian) Kouadio, 1 & Trefry, J. H. (1987). Sediment trace metal contaminations in the Ivory Coast, West Africa. Water Air Soil Pollut. 2,1. 145-154. Krynitsky, A. J. (1987). Preparation of biological tissue for determination of arsenic and selenium by graphite furnace atomic absorption spectrometry. Anal. Chem. 59(14), 1884-1886. Kusakabe, M., Ku, T. L., Harada, K., Tagushi. K. & Tsunogai, S. (1988). Chernobyl radioactivity found at the sediment- water interface in the North Pacific and Bering Sea. Geophys. Res. Lett. 15(1), 44-47. Larsen, P., Gadbois, A. & Johnson, A. ( 1 98 1 ). Distribution of polycyclic aromatic hydrocarbons in the sediments of Casco Bay. Bull. Environ. Contam. Toxicol. 30(5), 530-538. Lee, M. L., Novotny, M. V. & Bartle, K. D. ( 198 1 ). Analytical chemistry of polycyclic compounds. Academic Press, New York, Appendix 5, 441-449. Lisitsyn, A. P. (1989). Sedimentation system of ocean: a new modem approach to studying global and regional pollution. Proceedings of the Academy of Science USSR 4, 57-67. (in Russian) Liss, P. S. & Slater, P. G. (1974). Flux of gases across the air- sea interface. A'on/rt? 247, 181-184. Loring, D. H. (1984). Trace-metal geochemistry of sediment from Baffin Bay. Can. J. Earth Sci. 21, 1368-1378. Mackay. D., Shiu, W. Y. & Sutherland, R. P. (1979). Determination of air-water Henry's Law constants for hydrophobic pollutants. £nv/ra«. Sci. Technol. 13,333-337. Mackay, D. & Yeun, A. T. K. (1983). Mass transfer coefficient correlations for volatilization of organic solutes from water. Environ. Sci. Technol. 17,211-217. Macko, S. A. ( 1981 ). Stable nitrogen isotope ratios as tracers of organic geochemical processes. Ph. D. dissertation, University of Texas, Austin. Macko, S. A., Lee, W. Y. & Parker, P. L. (1982). Nitrogen and carbon isotope fractionation by two species of marine amphipods: Laboratory and field studies. J. Exp. Mar. Biol. Ecol. 63. 145-149. Maeda, M. ( 1986). Transport ofcopper from the Bering Sea to the north-western North Pacific. J. Oceanogr. Soc. Jpn. 42(5), 333-346. Malaiyandi, M., Shah, S. M. & Lee, P. (1982). Fate of ct- and y-hexachlorocyclohexane isomers under simulated environmental conditions. / Environ. Sci. Health A17, 283-297. 349 Malins, D. E., Margaret, M. M., Myers. M. S., Rhodes, L. D., Brown, D. W., Krone, C. A., McCain, B. B. & Chan, S. L. (1985). Toxic chemicals in sediment and biota from a creosote-polluted harbor: Relationship with hepatic neoplasms and other hepatic lesions in English sole (Pcirophiys vetulus). Carcinogenesis (10), 1463-1469. Mallet. L., Perdrian, A. & Perdrian, J. ( 1979). Pollution of BaP-type PAH in western regions of the Arctic Ocean. C. R. Acad. Sci.. Paris, 256, 34-87. Manual on the Determination of Trace Toxic Contaminants in the Sea Water( 1982). Gidrometeoizdat Publishers, Leningrad 42, 29. (in Russian) Martin, J. H. & Broenkow, W. W. (1975). Cadmium in plankton: elevated concentrations off Baja, California. Science 190, 884-885. McCrea, R. C. & Fischer, J. D (1986). Heavy metal and organochlorine contaminants in the five major Ontario rivers of the Hudson Bay lowland. Water Polliit. Res. J. Can. 21, 225-234. Metcalf, R. L. (1955). Organic Insecticides, their Chemistry and Mode of Action, Interscience, New York. Mill, T., Mabey, W. K., Lan. B. Y. & Baraze, A. (1981). Photolysis of polycyclic aromatic hydrocarbons in water. Chemosphere 10(11/12), 1281-1290. Minigawa, M. & Wada, E. ( 1986). Nitrogen isotope ratios of red tide organisms in the East China Sea: A characterization of biological nitrogen fixation. Mar. Chem. 19, 245-259. Mix, M. & Shaffer, R. ( 1983 ). Concentrations of unsubstituted polycyclic aromatic hydrocarbons in soft shell clams from Coos Bay, Oregon. Mar. Polhii. Bull. 14(3), 94-97. Miyake, Y. & Wada, E. ( 1 967 ). The abundance ratio of ' ■ N/'-'N in marine environments. Rec. Oceanogr. Works Jpn. 9, 37-53. Monk, H. E. (1961 ). Recommended methods of analysis of pesticide residues in food stuffs. Report by the Joint Mercury Residue Panel. Anal. Chem. 82,608-614. Montgomery, J. R. & Mckim, J. (Pers. Comm.). Dissolved labile and total cadmium in the Bering Sea. Data was obtained during the Second Joint US-USSR Expedition to the Bering Sea, Summer 1984. Muir, D. C. G., Norstrom, R. J. & Simon, M. (1988). Organochlorine contaminants in Arctic marine food chains: Accumulation of specific polychlorinated biphenyls and chlordane-related compounds. Environ. Sci. Technol. 22, 1071-1085. Muir, D. C. G., Ford, C. A., Grift, N. P., Metner, D. A. & Lockhart, W. L. ( 1 990b ). Geographic variation of chlorinated hydrocarbons in burbot {Lola lota) from remote lakes and rivers in Canada. Arch. Environ. Contani. To.xicol. 19, 530-542. Muir, D. C. G., Grift, N. P., Ford, C. A., Reiger, Q. W.. HendzekM. R. & Lockhart, W. L. (1990a). Evidence for the long-range transport of toxaphene to remote Arctic and sub- Arctic waters from monitoring offish tissue. In Long-Range Transport of Pesticides and other To.xic Substances (D. Kurtz, ed.), pp. 329-346. Proceedings of the ACS Symposium, Toronto, Ontario, Canada, 1988. Lewis Publishers, Chelsea, Michigan. Nagaya, U. & Nakamura. K. ( 1991 ). Investigation of several fallout radionuclides in Pacific deep waters. In Proceedings of the First International Symposium on Integrated Globed Ocean Monitoring 2,4\5^25. Gidrometeoizdat Publishers. Leningrad. Newman, J. W., Parker, P. L. & Behrens, E. W. (1973). Organic carbon isotope ratios in quaternary cores from the Gulf of Mexico. Geochini. Cosmochim. Acta 37, 225-238. Nikitin, A. I, Medinets, V. I., Chumichev, B. B., Katrich, 1. Yu., Vakulovsky, S. M., Kozlo, A. 1. & Lepioshkin, V. I. ( 1988). Radionuclide pollution of the Black Sea after the Chernobyl accident as it was in October 1986. Atomnaya Energiya 65(2), 134-137. (in Russian) Norstrom, R. J., Simon, M., Muir, D. C. G. & Schweinsburg, R. E. ( 1988). Organochlorine contaminants in arctic marine food chains: Identification, geographical distribution, and temporal trends in polar bears. Environ. Sci. Technol. 22, 1063-1071. Oehme, M. & Ottar, B. ( 1984). The long-range transport of polychlorinated hydrocarbons to the Arctic. Geophys. Res. Lett. 11, 1133-1136. Paalme, L. & Gubergrits. M. ( 1976). Kinetics of separate and cophotodegradation of benzo(a)pyrene and 3- methylchloranthene. Proc. Est. Acad. Sci. Chem. Geol. 25(4), 271-275. (in Russian) Paalme, L. P., Kirso, U. E. & Urbas. E. R. (1983a). Is benzo(a)pyrene an indicator of carcinogenic pollution? Voprosy Onkologi 29(7), 74-79. (in Russian) Paalme, L., Uibonuu, H., Gubergrits, M. & Jacquignon, P. (1983b). The initiated oxidation of polycyclic arenes in aqueous solution. O.xid. Comm. 4( 1-4), 27-34. Pacyna, J. M. & Oehme, M. (1988). Long-range transport of some organic compounds to the Norwegian Arctic. Atmos. Environ. 22, 243-257. Patton, G. W., Hinckley, D. A., Walla, M. D., Bidleman, T. F. & Hargrave, B. T. ( 1989). Airborne organochlorines in the Canadian high Arctic. Tellus 418, 243-255. Peng, T. -H., Broecker, W. S., Mathieu, G. G., Li, Y. -H. (1979). Radon evasion rates in the Atlantic and Pacific Oceans as determined during the Geosecs Program. / Geophys. Res. 84, 2471-2486. Perkin-Elmer Corp. ( 1976). Analytical methods for atomic absorption spectrophotometry. Perkin-Elmer Corp.. Norwalk, Connecticut, USA. Plucker, F. E. ( 1970). Stable carbon isotope ratios of organic matter of Gulf of Mexico shelf sediments. M. A. thesis. University of Texas, Austin. Prokofyev, A. K., Oradavsky, S. G. & Georgievsky, V. V. ( 1981 ). Methods of determination of toxic pollutants in the sea water and bottom sediments. Proc. State Ocecmogr. Inst. 162,51-55. (in Russian) Rabek, J. F. ( 1982). E.xperimental Methods in Plwtochemistiy andPhotophysics. Vol. 1 , Mir Publishers, Moscow ( Russian translation). Rice, C. P., Eadie, B. J. & Erstfeld, K. M. (1982). Enrichment of PCB's in Lake Michigan surface films. / Great Lakes Res. 8, 265-270. 350 Roscigno, P. F. (ed.) (1990). Biogeochemical cycle of benzo(a)pyrene. In Results of the Second Joint US-USSR Bering Sea Expedition, Summer 1984. US Fish Wildl. Sen:, Biol. Rep. 90(3), 219-22&. Sackett, W. M. & Thompson, R. R. (1963), Isotopic carbon composition of recent continental derived clastic sediments of eastern Gulf Coast, Gulf of Mexico, Bull. Am. Assoc. Petrol. Geologists 47. 525-531, Saleh, F, Y„ Dickson, K, L, & Rodgers, J. H, , Jr,( 1982), Fate of lindane in the aquatic environment: Rate constants of physical and chemical processes. Environ. To.xicol Chem. 1, 289-297, Sapozhnikov, V, V, (1982), Formation of the common salt composition of sea water and its physicochemical properties, pp, 172-240, In Pacific Ocean, Nysl Publishers, Moscow. (in Russian) Shabad, L, M, (1982), Chemical carcinogens in man's environment. In Comprehensive Monitoring of Environmental Pollution, pp, 69-77. Gidrometeoizdat Publishers, Leningrad, (in Russian) Shpolsky, E, V,, Ilyin, A. A, & Klimov, A, ( 1952), Fluorescence spectra ofcoronene in frozen solutions. Trans. USSR Acad. Sci. 87, 935-939, (in Russian) Singh, H, B., Salas, L, J, and Stiles, R, E, ( 1983). Selected man-made halogenated chemicals in the air and oceanic environment. J. Geophys. Res. 88. 3675-3683. Sofer, Z, (1980), Preparation of carbon dioxide for stable carbon isotope analysis of petroleum fractions. Anal. Chem. 52, 1389-1391. Subramanian, B, R,, Tanabe, S,, Hidaka, H, & Tatsukawa, R, (1985), Bioaccumulation of organochlorines (PCB's and pp"-DDE) in Antarctic Adelic penguins collected during a breeding season. Environ. Pollui. Sci. A. Subramanian, B, R,, Tanabe, S,, Hidaka, H,, & Tatsukawa, R, ( 1983), DDT'sandPCB isomers and congeners in Antarctic Fish, Arch. Environ. Coniani. To.xicol. 12,621-626, Swackhammer, D. L.. Charles, M. J, & Hites, R. A, (1987), Quantitation of toxaphene in environmental samples using negative ion chemical ionization mass spectrometry. Anal. Chem. 59, 9\3>-9\7. Sweeney, R. E, & Kaplan, I. R, (1980), Natural abundance of '^N as a source indicator for near-shore marine sedimentary and dissolved nitrogen. Mar. Chem. 9, 81-94, Szefer, P. & Skwarzec, B. ( 1988). Distribution and possible sources of some elements in the sediment cores of the southern Baltic. Mar. Chem. 23. 109-129, Tanabe. S. (1985). Distribution, behavior and fate of PCB's in the marine environment. / Oceanogr. Soc. Jpn. 41(5). Tanabe, S. Tatsukawa, R. (1980). Chlorinated hydrocarbons in the North Pacific and Indian Oceans. J. Oceanogr. Soc. 7/7/;. 36, 217-226. Tanabe, S. & Tatsukawa, R. (1983). Vertical transport and residence time of chlorinated hydrocarbons in the open ocean water column. / Oceanogr. Soc. Jpn. 39, 53-62. Tanabe, S., Tatsukawa, R., Kawano, M. & Hidaka, H. (1982). Global distribution and atmospheric transport of chlorinated hydro-carbons: HCH (BHC) Isomers and DDT compounds in the western Pacific, eastern Indian and Antarctic Oceans. / Oceanogr. Soc. Jpn. 38, 137-147. Taylor. D. L., Schliebe, S. & Metsker, H. ( 1 989). Contaminants in blubber, liver and kidney tissue of Pacific walruses. Mar. Pol hit. Bull. 20. 465-468. Tsyban. A. V., Panov, G. V., Subbotin, V. G., Timoshenkova, N. P. & Chernyak, S. M. (eds.) (1988). Methodical Foundati(ms of Integrated Ecological Monitoring of the Ocean. Gidrometeoizdat Publishers, Moscow, (in Russian) Tsyban, A. V., Panov, G. V., Ventzel, M. V., Volodkovich, Yu. L. & Korsak, M. N. (1986). Long-term ecological investigation and impacts in background regions of the World Ocean. In Global Biospheric Monitoring, Vol. 3., pp. 45-60. Gidrometeoizdat Publishers, Leningrad, (in Russian) Tsyban, A. V., Shabad, L. M., Khesina. A. Ya. et al. (1984). Circulation and biodegradation of carcinogenic hydrocarbons of benzo(a)pyrene in the marine environment. Proceedings Acad. Sci. USSR 252(6), 1490. (in Russian) Tsyban. A. V., Volodkovich, Yu. L. & Belyaeva, O. L. ( 1987 ). Studying benzo(a)pyrene circulation in the Bering Sea. In Comprehensive Analysis of the Bering Sea Ecosystem, pp. 218-232. Gidrometeoizdat Publishers, Leningrad, (in Russian) Tsyban, A. V., Volodkovich, Yu. L., Panov, G. V., Khessina, A. La. & Yermakov, Ye. A. (1985). Distribution and microbial degradation of carcinogenic hydrocarbons as illustrated by benzo(a)pyrene in some regions of the world oceans. In Ecological Consequences of Ocean Pollution. pp. 45-60. Gidrometeoizdat Publishers, Leningrad, (in Russian) Uematsu, M. & Duce, R. (1986). Tracking the Chernobyl plume across the Pacific. Mariiimes 30. 1^. United States Academy of Sciences (1977). Drinking water and health. Washington, D.C., 602. Vakulovsky, S. M. (ed.) (1986). Methodological Recommendations on the Detertnination of Radionuclide Contamination. Gidrometeoizdat Publishers, Moscow, (in Russian) Vakulovsky, S. M, Nikitin, A. I & Chumichev, V. B. (1985 ). A contamination of the Arctic Seas by radioactive residues of west European factories. Atomnaya Energiya 58(6), 445^49. (in Russian) Van Noon, P.. Smit, R.. Zwaan, E. & Ziylstra, J. (1988). Pitfalls in the aquatic photochemistry testing of chlorinated aromatic compounds. Chemosphere 17(2), 395-398. Venkatesan, M. I. & Kaplan, I. R. (1982). Distribution and transport of hydrocarbons in surface sediments of the Alaskan outer continental shelf Geochim. Cosmochim. Acta 46. 2135-2149. Vinogradov, M. E. ( 1 990). About modem problems of study ing the ecosystem of the ocean. Proc. Acad. Sci. USSR 1, 88-97. (in Russian) 351 Volodkovich, Yu. L. & Belyaeva, O. L. (1987). Biogeochemical Yin, C. & Hassett, J. P. ( 1986). Gas-partitioning approach for cycles of benzo(a)pyrene in the Bering Sea ecosystem. In laboratory and field studies of mirex fugacity in water. Proceedings oftheThird Congress of Soviet Oceanographers, Environ. Sci. Technol. 20, 1213-1217. Vol. 1. , pp. 91-93. Gidrometeoizdat Publishers, Leningrad. Zeeman, S. I. ( 1992). Importance of primary productivity and (in Russian) CO, accumulation in the Bering and Chukchi Seas. Wada, E. & Hattori, A. (1976). Natural abundance of ''^N in (Subchapter 6. 2, this volume.) particulate organic matter in the North Pacific Ocean. Zell, M. & Ballschmitter, K. (1980). Baseline studies of the Geochim. Cosmochini. Ada 40, 249-251. global pollution. Fresenius Z. Anal. Chem. 300, 387^02. Yablokov, V. V. &Ostroumov,S. A. (1983). Nature Protection — Problems and Perspectives, 111 pp. Forest Industry Publishers, Moscow, (in Russian) 352 Chapter 9: ECOTOXICOLOGY Editors: MIKHAIL N. KORSAK & GREGORY J. SMITH Subchapter 9.1: Effects of Pollutants on Plankton Communities 9.1.1 Investigation of Negative Effects and Critical Concentrations of Some Toxic Substances on the Plankton Community MIKHAIL N. KORSAK'. TERRY E. WHITLEDGE*. VASSILIY M. KUDRYATSEV, and NILA V. MAMAEVA* ^Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR ^Marine Science Institute, University of Texas at Austin, Port Aransas, Texas, USA *Southeni Division of the Oceanographic Institute of the USSR Academy of Sciences, Oceanologiva, USSR Introduction In recent decades anthropogenic effects have contributed to pollution in the World Ocean and have decreased the natural ability of marine ecological systems forcontinued reproduction and regulation, especially in those regions where continuous pollution inputs occur (Izrael, 1979; Izrael & Tsyban, 1989). Since marine environmental pollution continues to occur, it is necessary to conduct ecotoxicological research on the effects on plankton. In order to predict the ecological consequences of marine pollution, it is necessary to understand the oceanographic and biological processes controlling the values and the limits of critical concentrations of different pollutants ( Izrael & Tsyban, 1989). The critical concentration concept means that the content of the pollutants in the aqueous medium will not initiate nonreversible changes in the ecosystem being considered. If pollutant concentrations are larger, then the value of critical concentration will lead to degradation and nonreversible changes of the plankton (Nosov & Syrotkina, 1981; Egorov etal., 1 984; Korsak& Egorov, 1985;Lifshits& Korsak, 1988; Izrael & Tsyban, 1989; Maximov et ai, 1989; Korsak & Timoshenkova, 1990). The results of ecotoxicological research has shown that the intluence of low concentrations of pollutants on a plankton community causes individual physiological effects in sensitive marine organisms. However, there may be no significant changes in the ecosystem that are expressed in the form of structural and functional changes of the main ecosystem characteristics such as primary production/destruction (P/D) coefficients, for example. The increase of a toxic contaminant influence in an ecosystem first results in a decrease of the number and biomass of the most sensitive plankton organisms. If a toxicant concentration increases further the most .sensitive organisms will be completely replaced by more resistant planktonic species that occupy the nearest ecological niche (Odum, 1975; Nosov & Syrotkina, 1981). In the final stage there will be a few species, but total biomass will possibly increase. During the Third Joint US-USSR Bering & Chukchi Seas Expedition, ecotoxicological experiments were performed on the basis of a "dose-effect" scheme (Lifshits & Korsak, 1988; Korsak & Timoshenkova, 1990). They were conducted with the purpose of determining the limits of natural variation of critical concentrations of a plankton community to benzo(a)pyrene (BaP), polychlorinated biphenyls (PCB's), cadmium (Cd), and copper (Cu) pollutants. The biological responses measured were primary production (P), bacterial production (B^,), and the total number of microzooplankton. Experimental Procedure Water samples for the experiments were collected from the surface with 5-1 plastic Niskin samplers. Nutrient samples were analyzed in the initial water for nitrate, ammonium, and phosphate using standard techniques. The experimental additions of 0.1, 1.0,5.0, and IOngofBaP/1; I.O, 10, 20, and 50 |ig of PCB/I; 2, 4, 10, and 20 |ig of Cu/I; 10, 20, 40, and 60 |ig of Cd/1 were made within 30 min after collection. The experimental bottles (150 ml) were placed in a shipboard deck incubator with flowing seawater under natural illumination. At the end of incubation unpreserved subsamples were used for the determination of the total number of microzooplankton as well as primary production and bacterial destruction using previous '"'C-methods (Egorov et ai. 1984). The data were then used for calculations of LC^o values (Liftshits & Korsak, 1988). Results The ecotoxicological data and critical concentrations of BaP, PCB's, Cu and Cd from experiments performed in the Bering and Chukchi Seas are presented in Tables 1-8 and Figs. 1-8. Those data show the range of toxicity of the investigated pollutants in the following decreasing toxicity: BaP, Cu, PCB's, Cd (Table 7, 8; Figs. 1-8). The LC,n values, which approximate critical concentration values for BaP during its influence on phyto- and microzooplankton in the Bering Sea, vary from 0.1 to \0\xgf[ in relation to primary production (Table 7). When microzooplankton are used as a biological target, the critical concentration values range from 0.05 to 7 ^ig/1 (Table 7). For the Bering Sea, the average critical concentrations for BaP on phyto- and microzooplankton were 3. 6and 1.0 (ig/1, respectively (Table 7). The most sensitive phytoplankton communities to 357 100 50 Station 3 10 Copper Concentrations (pg/1) 20 f \ t \ 1 \ 100- "^ -< \ \ Station 45 iO- \ - ^ P "" ^ ~~~ ~~^ N 2 4 10 Copper Concentrations. (|ig/ll ^^^^^__ Station 7 rceniage N \ \ \ \ P S. 50- \ \ \ \ \ 4 10 Copper Concentrations (|jg/l) 20 100 50 10 Copper Concentrations (|jg/l) Station 89 20 ^ -^^ Station 9 100- \ \^ \ ^"\ P \ 50- ^"-.^ ~~ -_ N 4 10 Copper Concentrations (|jg/l) 20 Fig. 1 . Negative effects of Cu concentrations on primary production (P) and the total number of infusoria (N) on Stations 3. 7, and 9. 100 Station 110 10 Copper Concentrations Ipg/I) 20 Fig. 2. Negative effects of Cu concentrations on pnmary production (P) and the total number of infusoria (N) on Stations 45, 89, and 1 10. BaP additions were located in the Bering Sea on Station 3, and microzooplanlcton on Stations 7 and 9 (Tables 1,5; Figs. 6.7). It should be noted that toxicity tolerance of BaP increased from Station 3 to Station 7 (from 0.1 to 10 ^g/l, Figs. 6,7; Table 1 ) when primary production is used as a biological target. A toxicity tolerance of the bacterioplankton community to BaP was higher than for phytoplankton and the bacterial production rates in ecotoxicological experiments were much larger than in control bottles (Tables 1,5). This stimulation effect can probably be explained by the influence of released organic matter from dead plankton organisms. The data of primary and bacterial production obtained in ecotoxicological experiments can be used to calculate P/D coefficient changes under different additions of pollutants (Table 5; Fig. 8). The P/Bp coefficients were calculated and found to be in good correlation with P/D coefficients, which we believe depend upon the stability of the whole plankton community (Odum, 1975; Izrael & Tsyban, 1989). The critical concentration of BaP to the plankton community ( target P/Bp) was calculated to be about 0.05 |ig/l (Table 8). It should be mentioned that the critical concentrations of BaP to the phytoplankton and microzooplankton population were the same order but higher than for the whole plankton community (Table 8). The critical concentration values of Cu (2-20 |ig/l) to phytoplankton had the same order of variation as BaP (Tables 1 ,2,7). The Bering Sea microzooplankton were found to have critical concentrations of Cu. about 2-15 |ig/l (Table 7; Figs. 1 ,2 ). The average critical concentrations of Cu for phyto- and microzooplankton in the Bering Sea were, correspondingly, 10 and 6 |ig/l (Table 7). The phytoplankton populations most sensitive to Cu additions were located on Stations 3 and 89. and for microzooplankton, correspondingly, on Stations 7 and 9 (Figs. 1.2). It is necessary to mention that bacterial production increased in ecotoxicological experiments on Stations 3 and 4 with larger Cu concentrations, but in other areas on Stations 7 and 35, the values of bacterial production decreased significantly (Table 4). The critical concentration of Cu (target bacterial 358 100 50 Station 3 P 10 20 40 60 Cadmium Concenlralions (pg/ll 00- __- — '"^x Station 3 \ \ \ \ \ \ \ ^ P 5U- \n ^^-^^ ~~~~— ;^l^.^__ 10 20 50 PCB Concentrations (pg/1) 100 S 50 N 10 20 40 Cadmium Concentrations (pg/1) 60 00 Station 7 50 ^■O:^ 10 20 50 PCB Concentrations (pg/1) 100 - 50 10 20 40 Cadmium Concentrations (pg/1) 60 Fig- 3. Negative effects of Cd concentrations on piimary production (?) and the total number of infusoria (N) on Stations 3. 7, and 9. production) for bacterioplankton in Anadyr Bay, on Stations 35 and 7. were very close to critical concentrations for phyto- and microzooplankton in the same area (3-20 |ig/l). The value of P/Bp coefficient increased together with Cu concentrations on Station 7, and we think that 3 |ig/l Cu was very close to the critical concentration for the whole plankton community because this toxic effect disturbs the balance of organic matter significantly (Table 6; Fig. 8). Low bacterioplankton tolerance on Station 35 to Cd and Cu additions probably depends upon the high level of primary production and biomass of phytoplankton. which can suppress bacterioplankton (Tables4,6). The phytoplankton populations most sensitive to Cd additions were located on Stations 3 and 9, and the most sensitive microzooplankton populations were at Station 7 (Table 2; Fig. 3). The average Cd critical concentrations for phyto- and microzooplankton in the Bering Sea ecosystem were 40 and 28 |ig/l, respectively (Table 7 ). The critical concentration of Cd to the whole plankton community ( P/Bp - target) on Station 3 was nearly 8 |ig/I (Tables 6,8 ). It was noticed that the sensitivity of plankton to Cd additions, as well as to additions of BaP and Cu, varied significantly among different stations (Tables 1-8; Figs. 1-7). The sensitivity of 100- 50- 20 PCB Concentrations (^ig/l) 50 Fig. 4. Distribution of benthic biomass (gm-) at stations in the Gulf of Anadyr and neighboring waters. Station 100-, PCB Concentrations (pg/1) ^ Station 45 00- \ ^^^ 50- ^-^ ^P ----___ _ _ _ __N 20 PCB Concentrations 50 (|Jg/l) Fig. 5. Negative effects of PCB concentrations on primary production (?) and total number of infusoria (N) on Stations 18 and 45. 359 Station 3 0.1 1 5 10 Benzo(a)pyrene Concentrations (pg/i) 100 50- ^N — V- Station 45 0.1 1 5 10 Benzo|a)pyrene Concentrations (|ig/l) 100- 50- Station 7 0.1 1 5 Benzo(a)pyrene Concentrations (jag/l) 10 100 50- Station 9 Benzo(a)pyrene Concentrations (pg/1) Fig. 6. Negative effects of BaP concentrations on primary production (P) and total number of infusoria (N) on Stations 3, 7, and 9. phytoplankton and microzooplankton to toxicants varied over a range of about one order of magnitude for all values (Table?). Concerning the PCB's additions, it should be noted that the highest toxicity on the phytoplankton community was found on Stations 3 and 7, and for microzooplankton on Stations 18 and 41 (Figs. 4,5). The average critical concentrations of PCB's for phyto- and microzooplankton in the Bering Sea ecosystem were 30 |ag/l and 1 1 |ig/l, respectively (Table 7). The strongest PCB's toxic effects on bacterial production were found at Stations 3 and 4, and critical concentrations to the bacterioplankton community were about 50 )ag/l (Table 3). It was very surprising that on Station 35, additions of Cu, Cd, and BaP had a very strong negative effect, but toxic amounts of PCB's additions showed that values of bacterial production were stimulated (Tables 3 and 4). The PCB ' s critical concentrations for the whole plankton community calculated for Station 3 were about 5 |ig/l (Table 5 ). The critical concentrations data obtained in the Chukchi Sea ecosystem showed that values of critical concentration of BaP (target Station 53 Fig. Benzo(a)pyrene Concentrations (pg/1) 7. Negativeeffactsof BaP concentrations on primary production (P) and total number of infusonia (N) on Stations 45 and 53. primary production and microzooplankton) were significantly less than in the Bering Sea ecosystem (Tables 7,8). At the same time, the effects of heavy metals and PCB's on primary production in the Bering Sea were slightly stronger than in the Chukchi Sea ecosystem (Tables 7.8). The critical concentration of BaP and PCB's on infusoria of the Chukchi Sea was three and two times lower than the Bering Sea, while the effects of Cu and Cd were slightly higher (Tables 7,8). The above mentioned differences in the sensitivity of plankton communities can be ascribed to the difference in adaptation of these communities to the pollutants and also to their species composition. It should be noted that the temperature of the water in the Chukchi Sea during our studies was about 5°C lower than that in the Bering Sea. For this reason, the comparative resistance of the plankton communities of the Chukchi Sea to the toxic contaminants would be even less than was determined in the course of these ecotoxicological experiments (Oduni, 1975; Izrael & Tsyban, 1989). Discussion The values of critical concentrations of the pollutants obtained in our experiments of 1984 and 1988 show that the resistance of the plankton community of the Bering Sea for the summer period were similar for Cu and Cd ( Liftshits & Korsak, 1988; Izrael & Tsyban, 1989). In addition. Station 35 near St. Lawrence Island, which had the highest levels of primary production, was the most sensitive to all toxic contaminant additions, both in 1984 and 1988. Further study is needed to 360 350- 1 \ Station 3 Slation 7 300- Copper iMgfll Copper (Mg/I) 250- ^- -^ ' f'Bp 200- ISO 100 J'" P 150- ~V____ \^ ^ 50 I-C50 ■\ 50- V ^P/Bp " ' - P 2 4 10 20 LC,o 2 4 10 20 \\ r ^^ /^ 250- 1 Station 3 250- 1 '~^ ?on- / Cadmium (^g/l) 200- Station 3 150- / ... p 150- 100- benzotalpyrene (^jg/I) 50- \^ 50- , L^^O-- . .-__I!^ ^4 _ _ _ P/Bp ascertain the cause of the relatively low resistance to plankton organisms in this part of the Bering Sea to these toxic contaminants. Comparing the data obtained in the Bering and Chukchi Seas in 1988 and similar experiments performed in the Baltic Sea in 1987, it should be noted that the ranges of critical concentrations of the investigated pollutants were very similar (Tables 7,8) (Liftshits & Korsak, 1988; Korsak & Timoshenkova, 1990). It is evident that the resistance of the plankton community of the Baltic Sea to BaP and PCB's was lower than in the Bering Sea (Korsak & Timoshenkova, 1990; Liftshits & Korsak, 1988). On the other hand, the resistance of plankton of the Bering and Chukchi Seas to Cu and Cd was much lower than that in the Baltic Sea (Liftshits & Korsak, 1988; Korsak & Timoshenkova, 1990). These differences are probably very significant because the temperature of the Bering/Chukchi Sea water was 10°C lower than during the research in the Baltic Sea. As a result of these investigations, it should be noted that from the number of pollutants under consideration, the most dangerous pollutants to the plankton communities of the Bering, Baltic, and Chukchi Seas are BaP and Cu, because the maximum concentrations of these pollutants in the water are nearly the same values as the critical concentrations. The other pollutants investigated appear less hazardous to the plankton communities. 10 20 Fig. 8. Variations of some functional characteristics (p,BP.P/Bp) in ecotoxicalogica! experiments. TABLE 1 The toxic effects of PCB's and BaP to primary production in ecotoxicological experiments (relative values of primary production represented in %). Pollutant Station Number Pollutant pgBaP/l Station Number pg PCBs/1 3 7 8 18 45 3 7 9 45 53 0 100 100 100 100 100 0 100 100 100 100 100 0.1 100 62 112 160 130 0.1 43 89 102 72 126 LO 20 15 97 140 93 1.0 12 140 78 38 67 5.0 17 43 102 64 67 5.0 7 62 48 38 46 10.0 2.0 33 - 44 45 10.0 5 57 -- 44 65 361 TABLE 2 The toxic effects of Cu and Cd on primary production in ecotoxicological experiments (relative values of primary production in %). Pollutants Station Number Pollutants Statior Number HgCu/1 3 7 9 89 110 113 lag Cd/1 3 7 9 0' 100 100 100 100 100 100 0 100 100 100 2 87 112 135 82 86 109 10 104 120 125 4 60 136 114 85 83 92 20 88 115 118 10 61 127 156 71 74 81 40 84 128 96 20 31 122 84 48 64 31 60 82 108 90 TABLE 3 The toxic effects of BaP and PCBs on bacterioplankton in ecotoxicological experiments (relative values of bacterial production in %). Pollutant |jg/l Station Number 3 4 5 35 45 50 0 100 100 100 100 100 100 0.1 230 — 154 76 88 55 BP 1.0 280 152 120 50 95 100 5.0 250 360 114 13 100 96 10.0 360 370 94 18 95 52 0 100 100 100 100 100 100 0.1 100 109 140 160 116 78 CB 1.0 71 84 160 180 100 67 5.0 66 71 136 155 73 64 10.0 55 75 120 130 67 42 TABLE 4 The toxic effects of Cu and Cd on bacterioplankton in ecotoxicological experiments (relative values of bacterial production in %). Pollutant \ig/\ Station Number 7 35 45 50 72 96 Cu Cd 0 100 100 100 100 100 100 100 100 2 440 220 102 144 234 103 200 150 4 590 1030 77 33 257 108 238 192 10 545 665 65 20 257 160 252 240 20 1260 360 64 7 300 170 440 160 0 100 100 1(X) 100 100 100 10 250 270 59 75 430 93 20 560 1030 63 18 250 200 40 573 1140 66 8 120 87 60 1200 1130 48 0.9 110 77 362 TABLE 5 Variations of primary (Pi. bacterial production (B,,) and P/B,, coefficient in ecotoxicological e.xperiments. Pollutant Station 3 Station 45 Pollutant PCB ng/l Station 3 Station 45 BaP ng/1 P Bp P/B,, P B,. P/B, P Bn P/B, P Bp P/Bp 0 78 34 2.3 36 84 0.43 0 78 34 2.3 36 84 0.43 0.1 34 78 0.44 26 74 0.35 0.1 78 34 2.3 47 98 0.48 1.0 9.4 95 0.10 11 80 0.14 1.0 16 24 0.65 33 84 0.39 5.0 5.5 86 0.06 14 85 0.16 5.0 13 22 0.60 24 61 0.39 10.0 3.9 121 0.03 16 80 0.20 10.0 1.6 19 0.08 16 56 0,29 TABLE 6 Variation.s of Primary (P) and bacterial production (Bj,) and P/B, coefficient in ecotoxicological experiments. Pollutant Station 3 Station 7 Pollutant Station 3 Station 7 Cu ng/1 P Bp P/B, P Bp P/B, Cd |ig/l P Bp P/B, P Bp P/B, 0 78 25 3.1 15 145 0.10 0 78 25 3.1 15 145 0.10 2 68 108 0.62 17 148 O.ll 10 81 62 1.3 18 86 0.21 4 46 147 0.31 20 112 0.18 20 69 138 0.50 17 92 0.19 10 48 135 0.36 19 94 0.20 40 66 142 0.47 19 95 0.20 20 24 313 0.08 18.3 92 0.20 60 64 300 0.22 16 70 0.23 Values of primary (P) and bacterial production (B ) in mg C/mVday. TABLE 7 The values of "critical"" concentrations of some pollutants in the Bering Sea ecosystem. Pollutant Critical concentrations* |ig/l Primary Bacterio- Plankton Production Infusoria plankton (P/B,) TABLE 8 The values of critical concentrations of some pollutants in the Chukchi Sea ecosystem. Pollutant Critical concentrations* |ig/l Primary Bacterio- Plankton Production Infusoria plankton (P/B,) BaP PCBs Cu Cd 0.1-10.0 0.05-7 3.6 1.0 6-50 1-20 30 11 2-20 2-15 10 6 25-60 5-60 40 28 10.0 50.0 3 - 20 15 -60 0.05 1 -3 * Above the fraction bar - the range of variation for the critical concentrations of pollutants; below the fraction bar - the average values. BaP PCBs Cu Cd 0.5-1.0 0.75 0.15-0.5 0.32 30-40 35 l-IO 5 15-10 12 6-10 8 40-60 50 10-60 30 35 60 0.05 50 * Above the fraction bar - the range of variation for the critical concentrations of pollutants; below the fraction bar - the average values. 363 9.1.2 Effects of Hexachlorocyclohexane on Nitrogen Cycling in Natural Plankton Communities RAYMOND N, SAMBROTTO', DANIEL A. HINCKLEY* . ROGER B. HANSON*, and NILA V. MAMAEVA* ^Lximont-Doherty Geological Obsenatoiy of Columbia University. Palisades, New York. USA *EA Engineering Science and Technology. Hunt Valley. Maryland, USA *Skidaway Institute of Oceanography, Savannah, Georgia, USA "Southern Division of the Oceanographic Institute of the USSR Academy of Sciences, Gelendzhik-7, Oceanologiya, USSR Introduction Man-made substances find their way into the ocean by both direct run off from land and by atmospheric transport. In the case of atmospheric transport, pollutants can be spread to areas far from their point of origin (Flegal & Patterson, 1983); therefore, the question arises as to what effects this input will have on the plankton of the open ocean. The gamma isomer of hexachlorocyclohexane (y-HCH) has been used widely as the pesticide lindane. This report describes the results of on-board experiments designed to investigate the effects of hexachlorocyclohexane (HCH) on natural plankton communities in the Bering Sea. A variety of pollutants produce measurable toxic effects on marine plankton. These pollutants include a wide variety of herbicides, insecticides, fungicides, and organochlorines such as DDT (Butler, 1977). Most relevant to this work, the pesticide y-HCH exhibited toxic effects on marine algae in laboratory studies (Ukeles, 1962; Daste & Neuville, 1974; Moore & Dorward, 1974; Neuville era/., 1974). Additionally, HCH can be transported by the atmosphere to the open ocean. High latitude seas appear to be particularly susceptible to such inputs because HCH is more soluble at the low temperatures commonly found there (Hinckley etai. Subchapter 8.1.1, this volume). However, it is difficult to extrapolate most laboratory studies into accurate predictions as to the specific effect of pollutants on marine plankton. In the ocean, pollutant concentrations are much lower than those used in most laboratory experiments. Also, laboratory experiments cannot duplicate the community diversity of most ocean plankton systems. Our goal in the present work is to provide a better basis on which to assess the effects of HCH on marine biota by examining the effects of HCH on natural communities at concentrations approaching the actual pollutant levels measured in the ocean. Methods Results of two separate experiments carried out during the cruise of the RA' Akademik Korolev to the Bering Sea in August and September 1988 are presented here. The basic protocol for both experiments was similar. Near-surface (5 m) water was collected using clean techniques that included the use of a go-flow ™ bottle on a kevlar^"^ wire. The samples were then transferred to acid-cleaned 5-1 polyethylene containers and incubated on-deck in incubators cooled with surface seawater. The source water for the two experiments was chosen to provide contrasting high latitude plankton communities. The first experiment was started 2 1 August 1 988 with surface water collected at 65°5.2'N and 170°42.7'W (Station 96) that had a total water depth of 42 m. This experiment will hereafter be called the shelf experiment. The second experiment was started 26 August 1 988 with surface water collected at 54°25.3'N and 176°43.7'W (Station 108) that had a total water depth of 3,835 m; this will be referred to as the "oceanic experiment." Selected ambient characteristics of each sampling site are shown in Table 1 . Table 1 Characteristics of the water collected for the two HCH experiments. Shelf Experiment Oceanic Experiment (Station 96) (Station 108) Collection date 8/21/88 8/26/88 Latitude 65°5.2'N 54°25.3'N Longitude I70°42.7'W 176°43.7'W Water depth (m) 42 3835 Temperature (°C) 2.33 9.17 Salinity ("/,„) 32.73 33.12 Oxygen saturation (%) 98.1 104.0 POj(nM) 2.83 2.71 Si(OH,)(nM) 36.20 34.17 NO, + NO;(N+N;|iM) 21.11 20.70 NH,(nM)" 0.58 1.92 Chlorophyll (7 (Hg 1 ') 6.3 0.72 Bacteria (10" cells/1) 2.4 3.0 Ciliates(#/I) 10,000 364 In each experiment, the water was subdivided into three 7.5-1 containers a control that was not modified in any way; an experimental container to which the HCH in an acetone solvent was added; and a solvent control that was treated only with the same amount of acetone that was used as the carrier for the HCH. In the oceanic experiment, the HCH treatment was replicated. At 0, 24, and 48 h after the experiments were started, samples were withdrawn for each of the following measurements: /. The concentration of HCH was routinely measured in each container by withdrawing 1 0 ml samples. In the oceanic experiment, the amount of HCH that adhered to the container walls was also measured by washing down the container walls with solvent at the end of the experiment. The specific amounts of HCH and HCH already present in the ambient water, as well as that added to the experimental containers, is shown in Fig. 1. 2. The concentration of nutrients, including nitrate and nitrite ( N+N ), ammonium ( NH4), phosphate ( PO4 ), and silicate (SKOHlj), were measured on an autoanalyzer using conventional autoanalyzer techniques on 50-ml samples (WhMedgc etal., 1981). 3. The concentration of chlorophyll a was measured by the extracted fluorescence method on 50-ml samples (Parsons eial.. 1984). 4. The rates of ammonium uptake were measured by the "N tracer method on 1 1 samples (Sambrotto et al., 1986). 5. Bacterial counts were obtained from staining and direct microscopy, and bacterial activity was measured by the 'H thymidine technique on 1 50-ml samples (Fuhrman & Azam, 1982). 6. Microzooplankton abundance and was estimated from ciliate counts. These were done immediately on board by microscopic counting of unstained 100-ml samples. 7. Additional volume was withdrawn from the experimental containers for other measurements that are not discussed here. The combined volume requirements of all samples were accommodated within the experimental design and the limitations imposed by the 7.5-1 containers. Results The amount of HCH added to the experimental containers at the beginning of each experiment was composed of equal parts of the a and y isomers (Fig. la). In all experimental containers, the concentration of HCH decreased over the 48-h period. The net loss of total HCH in the shelf and oceanic replicate #1 were similar, although the net loss in oceanic replicate #2 was almost 50% greater (Fig. Ic). In the oceanic replicates, the net loss of a HCH was slightly greater than that for Y -HCH. Functionally, the remaining measurements fall into one of three groups. Group 1 measurements are those that reflect only the biomass of the organisms in the containers and include chl a. bacterial counts, and ciliate counts. Group 2 measurements a) CD d X b) X o 100 80 60 40 20 0 100 80 60 40 20 0 ; E ; '; ■ z 31 48 hrs. : 3/2 / 45 hrs Ambient n .— ^ ft ■ 30 , JJl 1 t u — -L c E nj DC a: I i o 00 DC C\J IT c\j DC CM DC « ffl E - « g I ^ g C) Shelf expt. Oceanic R.#f Oceanic R.#2 Fig. I . The concentrations of a and y isomers of HCH in the experimental (HCH) containers at the beginning and end of the shelf (Fig. la) and oceanic (Fig. lb) experiments. Also shown are the total HCH concentrations in the ambient water when it was first collected and the concentrations recovered from the walls of the containers at the end of the oceanic experiment. Each value is the result of two analyses. Fig. 1 c summarizes the net changes in each isomer in the experimental containers over the 48 h periods. are those that reflect both biomass and specific activity and include bacterial activity and net changes in ambient nutrients. Group 3 measurements reflect only the specific uptake rates of 365 the plankton and include the NHj uptake rates as well as the bacterial activity on a per-cell basis. To further organize the experimental results, the data are presented as the net changes observed during the 48 h of the experiments (i.e., the measurement at the time of observation minus the initial [Otime] measurement). Chlorophyll a levels increased dramatically in all of the containers in the shelf experiment (Fig. 2). The increase was less in the incubations exposed to acetone (the acetone control and the HCH containers). The observed increases in chl a levels in the oceanic experiment were much less than those on the shelf. Unfortunately, the untreated control in the oceanic experiment ran out of sample volume before the final chl a sample could be taken. The 48-h increase in bacterial numbers was the same for both the acetone control and HCH experimentals in both shelf and oceanic experiments (Fig. 3). However, the changes in bacterial numbers relative to the untreated control were very control acetone HCH rep.#1 HCH rep.#2 Fig. 2. Net 48 h changes in chl <; concentration in the untreated control, acetone control and HCH experimental containers. Initial values for each expenment are given in Table 1. control HCH rep,#1 HCH rep. #2 Fig. 3. Net 4X h change in bacterial numbers in the untreated control, acetone control and HCH experimental containers. (Note that untreated shelf control did not change). Initial values tor each experiment are given in Table 1. different between the shelf and oceanic areas. In the shelf experiment, bacterial numbers in the acetone and HCH containers increased more than the untreated control (which did not change). In the oceanic experiment, the opposite change occurred. There also was a difference between the shelf and oceanic response on the basis of bacterial activity (thymidine incorporation; Fig. 4). There was little difference between the treatments and controls in the shelf experiment. However, in the oceanic experiment, acetone markedly depressed activity. The presence of HCH appeared to make up for this inhibition in that bacterial activity in the HCH experimentals were similar to the untreated control. Changes in ciliate abundance are only available for the shelf experiment (Fig. 5). Ciliate numbers decreased in all containers. However, the decrease in the acetone control was less than either the untreated control or the HCH experimental. The 48-h changes in the concentration of dissolved inorganic nutrients fall into one of three distinct categories: /. The effect of treatments on net 48-h changes are similar in both shelf and oceanic experiments and the effects of HCH cannot be distinguished from acetone alone. In this category 140 T 120 - 100 I 80 I 60 TO ^ 40 Q) O 03 20 CD ^'-' - ■ shelf □ oceanic \ — I 1 r 1 ■- HCH Rep#1 HCH Rep#2 Fig. 4. Net 48 h change in bacterial activity (thymidine incorporation) in the untreated control, acetone control and HCH experimental containers. Initial values for each expenment are given in Table 1 . n control acetone f- CH rep.#1 '^nnn ■ ■ 4nnn H finnn H nr\Pir\ 1 nnnn c3 Fig. 5. Net 48 h change in ciliate concentration in the untreated control, acetone control and HCH experimental container for the shelf experiment. 366 control acetone HCH rep #1 HCH rep #2 Fig. 6. Net 48 h change in phosphate concentration in the untreated control, acetone control and HCH experimental containers. Initial values for each experiment are given in Table 1 . are the observed changes in phosphate (Fig. 6). However, in the oceanic experiment, the net consumption of phosphate was greater in the HCH treated experimentals than in the presence of acetone alone. 2. The effect of treatments on net 48-h changes are opposite in shelf and oceanic experiments and the effects of HCH cannot be distinguished from acetone alone. In this category are the changes in N + N (Fig. 7) and silicate (Fig. 8). Acetone slowed the net consumption of ambient N + N in the shelf experiment (Fig. 7) but resulted in a net increase in N + N in the oceanic experiment (Fig. 7). Likewise, the presence of acetone slowed the consumption of silicate in the shelf experiment ( Fig. 8 ) and produced a net increase in silicate in the oceanic experiment (Fig. 8). 3. The effect of treatments on net 48-h changes are similar in both shelf and oceanic experiments, and in both locations the effects of HCH are distinct from acetone alone. The observed net changes in ambient ammonium are in this category (Fig. 9). In both the untreated and acetone-treated containers in both shelf and oceanic experiments, the ammonium concentrations control acetone HCH rep,#1 HCH rep.#2 control acetone HCH rep.#1 HCH rep.#2 Fig. 8. Net 48 h change in silicate concentration in the untreated control, acetone control and HCH experimental containers. Initial values for each experiment are given in Table I. 0.6^ 0.4 0.2 0 -0.2 -0.4 ■ shell jceanic r — - 1 1 1 control acetone HCH rep.#1 HCH rep. #2 Fig. 7. Net 48 h change in N+N concentration in the untreated control, acetone control and HCH experimental containers. Initial values tor each experiment are given in Table 1. Fig. 9. Net 48 h change in ammonium concentration in the untreated control, acetone control and HCH experimental containers. Initial values for each experiment are given in Table 1 . decreased. However, in all containers treated with HCH, the ammonium concentrations increased during the 48-h experiment. Like the changes in ammonium levels, the specific rates of ammonium uptake were higher in the HCH-treated containers attheendofbothexperiments(Fig. 10). In the shelf experiment, ammonium uptake rates increased in the acetone and HCH containers at 48 h. In the oceanic experiment, the ammonium uptake rates in the HCH-treated containers were markedly higher than either the untreated or acetone-treated containers at 48 h. Discussion The most significant findings from our experiments were the effects of HCH on plankton nitrogen cycling (Figs. 9,10). The results clearly indicate that the added HCH produced a measurable effect beyond that ofthe acetone carrier alone. The ambient ammonium pool is extremely dynamic and reflects the net result of uptake and regeneration processes. The fact that both the specific rates of ammonium uptake and the ambient 367 0.025 0 to -^ TO Q. 3 control acetone HCH rep.#1 HCH rep.#2 Fig. 10. Net 48 h change in ammonium specific uptake rates in the untreated control, acetone control and HCH experimental container for the shelf experiment. For the untreated control, acetone control and HCH experimental containers of the oceanic experiment, the measured values (and not the changes) are shown because the initial measurements for this experiment are not available. ammonium levels increased in the experimental containers suggests that HCH acted to increase net ammonium fluxes in both shelf and oceanic areas. The proportion of new to total nitrogen production (new plus regenerated) in the plankton can be related to the flux of carbon from surface waters (Eppley & Peterson, 1979). Therefore, any change in this ratio would affect the biogeochemical cycling of carbon as well as nitrogen. This is a subject of broad importance because the biological flux of carbon from surface waters is a major sink for atmospheric CO, and may be an important sink forrising levels of this greenhouse gas. The changes observed in our experiments suggest that atmospheric input of pollutants like HCH can decrease the amount of carbon exported from surface waters by increasing the amount that is regenerated in siiii. We feel that these results provide a basis for preliminary quantitative extrapolation for several reasons. This is one of the few studies to examine the effects of pollutants on natural populations of open ocean plankton. The amount of HCH added to the experimental containers (80-90 ng/1) was approximately 10 times the highest level of HCH yet measured in ocean water (Hinckley el ai. Subchapter 8. 1 . 1 , this volume). However, it is not unreasonable that localized, higher concentrations of HCH exist in the ocean. Also, although it is difficult to assess the effect of chronic (long-term ) exposure of marine plankton systems to pesticides, we suspect that the changes in nitrogen cycling also would have been observed at lower HCH concentrations in longer experiments. In addition to the potential increased regeneration induced by exposure to HCH, the literature on pollutant effects on plankton indicates that there are significant differences among the sensitivities ofplankton populations to pollutants. Although little information on the specific effects of HCH is available, a number of studies with other pollutants have shown that marine algal community changes are a much more sensitive indicator of toxic effect than specific measurements done on unialgal cultures. For example, in a number of studies, diatom populations were particulariy sensitive among the organisms studied (Maloney& Palmer, 1956:Men/,elt'r«/., 1970; Mosser el ai, 1972; Fisher el ai. 1974). This suggests that the combined effects of pollutants on carbon flux are greater than this preliminary HCH experiment suggests because diatoms are typically associated with high levels of new production and their sensitivity to pollutants would further reduce carbon flux. The results of the experiments can be interpreted in terms of the known biological differences between the shelf and oceanic regimes. The shelf and oceanic waters of the subarctic North Pacific differ markedly in the amount and character of phytoplankton productivity (Sambrotto&Lorenzen. 1986). In shelf areas of the eastern Bering Sea, intense, diatom-dominated blooms occur in the spring and summer months (Sambrotto el ai. 1986). However, in oceanic areas, the phytoplankton crop remains low throughout the year, despite an abundance of surt'ace layer nutrients, most likely due to intense grazing pressure by both macro- and microzooplankton (Frost, 1990). Thus the shelf and oceanic experiments provide insight into the reactions of two distinct plankton systems to airborne HCH. A complete analysis of the causality of the effects observed in the nitrogen system is not possible given the limited measurements made and the known complexity of plankton systems. However, observations on specific components of the community over the course of the experiments offer some insight as to the biological changes accompanying the changes in nitrogen cycling. Unfortunately, ciliate abundance data are available only for the shelf experiment and do not reflect any distinct effect of HCH. Volume restrictions at the end of the experiments contributed to the scatter in other measurements relating to biomass as well. For example, the chl a change for the replicates in the oceanic experiment varied widely and obscured the detection of any possible difference between the experimentals and acetone control. However, changes in the bacterial community are apparent, particularly if the data are examined on a per-cell basis ( Hanson el ai. 1988; Fig. 11). On this basis, HCH suppressed cell- specific activity on the shelf, while oceanic cell-specific activities increased. These differences closely parallel the observed changes in phosphate, which were also opposite in 300 ^250 control acetone HCH rep.#1 HCH rep #2 Fig. 1 1 . Net 48 h change in specific activity of thymidine incorporation per bacterial cell {based on the data in Figs. 3 and 4) in the untreated control, acetone control and HCH experimental container for the shelf experiments. 368 shelf and oceanic experiments (Fig. 6). These observations suggest that there is a causal link between the phosphate pool and bacterial activity. However, it is not known whether this effect is brought about directly by the bacteria or perhaps by reduced bacterial grazing by microtlagellates. Also, the fact that the response of the shelf community was opposite to that of the oceanic communities in terms of both bacterial activity per cell and net phosphate change may be an effect of the known biological differences between the communities. The oceanic community has a greater diversity of bacterial populations as well as a more highly developed microbial loop than shelf waters (Azam ct al.. 1983). Thus oceanic waters harborbacterial populations that can metabolize HCH and its metabolites, and in an active microbial loop, these populations would quickly exert dominance. In shelf waters, the rise in bacterial numbers in the treated containers (Fig. 3) may simply reflect diminished grazing pressure because the cell-specific activity for bacteria decreased here (Fig. 1 1 ). Wheeler and Kirchman (1986) suggested that bacterial uptake is an important sink for seawater ammonium. In the oceanic experiment the changes in cell-specific activity for bacteria and ammonium uptake rates are similar and, therefore, enhanced bacterial activity is one possible explanation for the elevated ammonium uptake rates. However, in the shelf experiment, cell-specific activity decreased in the same containers that ammonium uptake rates increased and, therefore, a similar cause and effect is less plausible here. The results of the HCH analysis on the wall washings (Fig. 1) indicate that little HCH was lost to wall adhesion andthat the HCH decreases observed over the experiments were due to chemical or biochemical breakdown. Therefore, the greater per-cell bacterial activity in the oceanic area may also be responsible for the slightly greater disappearance of HCH from the oceanic containers (around 35%) than from the shelf container (around 31%), particularly in the case of oceanic replicate #2, that exhibited the greatest net loss of HCH (Fig. 1 ); bacterial activity (Fig. 4); ammonium change (Fig. 9); ammonium uptake rate (Fig. 10); and bacterial activity per cell (Fig. 11). However, certain freshwater phytoplankton also have been shown to metabolize HCH (Sodergran, 1971; Singh, 1973) and hydrophobic pollutants are accumulated to varying degrees by marine phytoplankton (Rice & Sikka, 1973). Thus, neither the organisms nor the mechanisms responsible for the observed decrease in HCH can be identified in our experiments. This work was supported by NSF grant #DPP86 13769. This project was part of the Third Joint US-USSR Bering & Chukchi Seas Expedition aboard the Soviet research vessel Akademik Korolev. We express appreciation to the US Fish and Wildlife Service, USA, and the State Committee for Hydrometeorology, USSR, who made our participation possible. In addition, we would like to thank Dr. Richard Dugdale for analyzing the 13N samples and Dr. Clifford Rice for his helpful comments on pesticide effects. Last, but not least, we would like to thank the captain and crew of the R/V Akademik Korolev for their many contributions to our work at .sea. 369 Subchapter 9.2: Toxicity of Sediments to Test Organisms 9.2.1 Acute Toxicity Testing of Sediments PASQUALE F. ROSCIGNO, ARTHUR V. STIFFEY*, W. DAVID BURKE', and DIANE K. ARWOOD" WS Fish and Wildlife Sen-ice. National Wetlands Research Center, Slidell. Louisiana, USA Wflirt/ Oceanographic and Atmospheric Research Laboratory, Stennis Space Center, Mississippi, USA ' Gulf Coast Research Laboratory, Ocean Springs, Mississippi, USA • Department of Oceanography, University of Southern Mississippi, Stennis Space Center, Mississippi, USA Introduction The Bering and Chukchi Seas are rich with hving and energy resources valuable to both the USA and USSR. A balance between exploiting the petroleum reserves and conserving the unique structure and functions of the marine food webs must be attained if the Bering and Chukchi Seas are to remain productive ecosystems. As a response to this development, a program must be formulated that will serve to monitor and protect the important ecosystems of these seas (Hood & Calder, 1981; Izrael & Tsyban, 1986; Hale. 1987; Becker, 1988). A consensus has emerged that a comprehensive monitoring program must integrate chemical survey infomiation, single- species toxicity testing, and field survey data into an ecosystem- level evaluation of contaminants impact. Each of these approaches, taken separately, does not provide the information needed to protect living resources (Levin et al.. 1984; Long & Chapman, 1985; Izrael & Tsyban, 1986; Connell, 1987). While chemical surveys are important in detemiining the benchmark levels (Rice et al.. Subchapter 8. 1 .3, this volume; Krynitsky et al.. Subchapter 8.3.2, this volume) and the biogeochemical pathways of toxicants in the environment (Flegel & Patterson, 1983), little information about the contaminant's biochemical, physiological, and ecological effects can be obtained (Cairns & Pratt, 1987). Similarly, the utility of measuring individual species' response to environmental contamination has its limitations. Possible responses that can be measured include determining rates of biotransformation (Griffiths et al.. 1982), bioaccumulation and food-chain transfers ( Foster et al. . 1987). and single-species toxicity tests (Chapman & Long, 1983). Extrapolation from these single-species assessments of exposure to a determination of ecosystem-level adverse impacts cannot be properly deduced. Field survey data are often extremely complex and natural variability may mask perturbations caused by exposure to contaminants (Levin et al.. 1984). More sophisticated field experiments are needed to determine the impact of an invertebrate's exposure to a toxicant on its reproduction, immigration, and recruitment and to assess how these impacts change benthic community structure (Kimball & Levin, 1 985 ). The Sediment Quality Triad provides one model, from many that are being developed, that could serve as a framework. It encompasses chemical surveys, single-species toxicity testing. and field ecological assessments into an integrated assessment of the actual ecological impact of contaminants on living resources (Long & Chapman, 1985; Chapman, 1986). The object of this paper is to examine two single-species toxicity tests that might be useful candidate tests as rapid screening procedures in a comprehensive monitoring program. One test uses the brine shrimp, Artemia salina (an anostracan crustacean), and examines mortality of instar II and III nauplii as the end-point (See Fig. 1) (Persoone & Wells, 1987). The other uses the marine dinoflagellate Pyrocystis lunula and measures the suppression of bioluminescence as an end-point (See Fig. 2) (Stiffey, 1990). These two tests are applied to determine the acute toxicity of sediment samples (collected during the Third Joint US-USSR Bering & Chukchi Seas Expedition, 26 July-2 September 1988) to these organisms. 100 pm INSTAR I INSTAR II Fig. I. Morphology of nauplii ot\4r/('min. Materials and Methods INSTAR III Preparation of Sediments Sediment samples were collected as described by Rice et al. (Subchapter 8.1.3, this volume) and Krynitsky et al. (Subchapter 8.3.2, this volume). The sediment was stored at -4°C until analyzed in the laboratory. The suspended particulate phase of the sediment sample was used to determine whether these samples were acutely toxic to the test organisms. Sainples were thawed to room temperature and mixed in a blender until thoroughly homogenized (usually about 15 min), and filtered ( 1 micron- Whatman) 3.8% seawater was aerated and used for 373 Fig. 2. Drawing ofPyrocvi/is/H/iH/ii cells; the long axis ib> approximately 100 microns. preparing dilution water. A 500-ml sample of the sediment was poured into a 2,000-ml flask and seawater was added to bring the final volume to 1 1. This suspension was stirred for 5 min with a magnetic stirbar and the suspension allowed to settle for 1 h at 25°C. The liquid phase, which is the suspended particulate phase, was then poured into another 2,000-ml flask and stirred for 5 min; then the pH and dissolved oxygen (DO) were recorded. The pH was adjusted to 7.8, and if the DO was below 4.9 parts per million (ppm), the phase was aerated for 5 min. At that point, pH and DO were recorded for 20 min at 5-min intervals. This reaeration continued until DO was stabilized above 4.9 ppm. This test medium was used for toxicity testing (Federal Register, 1985). Artemia salina Toxicity Test The A. salina toxicity test was modified from several sources ( Peltier & Weber, 1985; Vanhaecke&Persoone, 1984; Persoone & Castrisi-Catharios, 1989; Persoone et al., 1989) and ARTOXKIT M (Persoone, State University of Ghent, Belgium). The following is a brief description of the procedure used. Artemia salina cysts were obtained from Aquarium Products (Glen Bumie. MD), with its cyst origin identified as Columbia. Filtered ( 1 |a-Whatman) 3.8% seawater was used for hatching the Artemia cysts and preparing the dilution water (Persoone (feCastritsi-Catharios, 1989). Hatching was initiated 48 h before the start of the toxicity test. A 2,000-ml separator/ funnel was used as an incubation chamber where 15 to 20 ml of Artemia cysts were added and mixed vigorously using an air stream for 24 h at 27°C under continuous illumination. Upon hatching, the nauplii were allowed to settle to the bottom of the separatory vessel and drained into a 250-ml beaker containing fresh dilution water. At the end of the 24-h incubation period, the larvae are at instar 1 of their life cycle (Fig. 1 ). The inslar I nauplii were incubated for another 24 h, in continuous light, at 27°C. Their positively phototactic response permits them to be concentrated near the vicinity of a light beam and allows for easier pipetting ( Peltier & Weber, 1 985 ). At this point, and for the duration of the exposure to the test medium, the larvae were at instar II-III stage (Fig. 1). The larvae were not fed during the entire procedure and no mortality was observed due to starvation. Two multiwell plates each consisting of 24 individual wells (3 ml) were used to test the elutriate produced from the processing of each sediment sample. Two replicates for each sediment sample were produced. In all, forty-four wells (20 experimental and 4 seawater controls) were used and positions within the multiwell plates were randomly assigned. One ml of the test elutriate was added to a well and 10 Artemia nauplii were added by micropipetting. The wells were then placed for 24 h in an incubator without light at 27°C. After the incubation period, each well was examined under a dissecting microscope using a xlO magnification and the live Artemia were counted. Mortality was determined if a larva was not observed moving for 10 seconds (Vanhaecke & Persoone, 1984). If any of the sediment elutriate samples showed any signs of mortality, a LC50 was calculated (Peltier & Weber, 1985). Pyrocystis lunula Toxicity' Test Pyrocystis lunula, a marine dinoflagellate, was maintained in f/2 medium, its composition given in Table 1 (Guillard & Ryther, 1962). Cultures of P. lunula were maintained at 20°C and illuminated with cool white fluorescent lamps shaded to a light intensity of 17 u-einsteins/cm-. The illumination cycle was 1 2 h light and 1 2 h dark. TABLE 1 Composition of f/2 Medium. Constituent Concentration NaNO, NaH,P04«H,0 Fe sequestrene' Na.SiOj'QHp Vitamins; Thiamine«HCL Biotin Trace Metals: CuS0j'5H,0 ZnS0/7H_,0 • CoCL,'6H,0 MnCL,'4H,0 Na_,Mo04«2H,0 Seawater* 150 nig 10 mg 10 mg (1.3 mg Fe) 30-60 mg (3-6 mg Si) 0.2mg 0.001 mg 0.001 mg 0.0196 mg (0.005 mgCu) 0.044 mg (0.01 mgZn) 0.020 mg(0.00.'i mgCo) 0.360 mg (0.1 mg Mn) 0.0126 mg (0.005 mg Mo) To 1 liter The medium is modified by the omission of silicate and the addition of TRIS buffer to increase the final pH to 7.6. ■ Sodium iron salt of ethylene dinilriloletraacetic acid (EDTA). " Artificial seawater is prepared from the formula of Lyman and Fleininy (1940). 374 Cells were counted in a Sedgwick-Rafter chamber and their concentration was adjusted to 100 cells/ml for use during the toxicity test. To be certain that the dinollagellate culture emits the maximum quantity of light, it is necessary that the culture be stirred vigorously. An acrylic rod was fitted into the chuck of a variable speed electric motor drive set at -100 rpm. During the test, the rod was inserted approximately two-thirds of the way into the vial containing the test medium and P. lunula cells and stirred for 2 min to ensure that the light producing ability of the dinoflagellate was exhausted. A solid state photometer ( Stiffey et al. , 1 985 ; Stiffey et cil. , 1987) measured biolummescence and a multirange stripchart recorder with a chart speed of 3 cm/min was connected to the photometer that was adjusted so that the recorder registered the cumulative light fluxes as a function of time (Fig. 3). PHOTOTUBE DDDII AMPLIFIIiR RliKlRDPK Fig. 3. Equipment used for the measurement of luminescence intensity. Station 3 7 9 13 18 22 35 45 47 50 55 59 61 64 67 69 75 96 109 110 TABLE 2 Stations Where Sediments Were Tested And Results of Toxicity Tests. Artcmia Pxrocx.sris The percentage of bioluminescent quenching was calculated with the following equation: % quenching : C-E X 100 where C = displacement of the reorder pen ( in mm) during the stirring of the control culture, and E = the displacement of the pen during stirring of the test elutriate (Stiffey, 1990). Depending on the degree of toxicity of the test medium, bioluminescence may be totally suppressed, or a degree of light diminution relative to seawater controls may be noted. If any decrease in bioluminescence was observed, an LC^,, was calculated (Peltier & Weber, 1985). Results and Discussion For the stations examined, none of the sediments appear to be acutely toxic to A. salina and P. luuuUi (Table 2). This agrees with the levels of contamination reported from this region detemiined by chemical analysis (Rice <»;«/.. Subchapter 8.1.3, this volume; Krynitsky et al.. Subchapter 8.3.2, this volume). Since toxicity was not observed, LC^„ values were not calculated. This illustrates the rapidity and cost-effectiveness of initial screening for toxicity. In a hierarchical approach to ecotoxicological assessment, a positive indication of toxicity would have triggered a series of assessment procedures where definitive toxicity tests, field experiments, and other investigations could be performed. A negative response allows resources to be redirected to areas of greater concern. These two toxicity tests showed great potential for use on research vessels and to generate timely information that could be pursued while the vessel is still on-station. During a catastrophe such as an oil spill, a rapid assessment of toxic impact can direct prevention and clean-up procedures, which can maximize the effort in protecting valuable fish and wildlife resources. The organisms are easy to culture and maintain and require very little in terms of space and equipment. End-points such as mortality or diminution of bioluminescence are easy to measure and provide clearly defined criteria for assessing the quality of the sediment. Several drawbacks in using these tests do exist and reflect not so much the limitations of these particular tests but the symptomatic problems confronting toxicity testing in general (Kimball & Levin, 1985). While the suspended particular phase testing is a proper approach for use with pelagic organisms such as Artentia and Pyrocystis, it is not a direct measure of sediment toxicity. It would have been desirable to use a sediment-dwelling organism. While much research is being conducted in the area of sediment toxicity testing, it as not as well developed as water-phase testing (Levin et al. , 1 984; Long & Chapman, 1985). The lack of cultured benthic species is a major limitation. With a wide spectrum of sediment types found in the marine environment and with each benthic species having its own tolerance for sediment substrate, the definitive marine sediment test that is rapid and cost-effect is still to be developed. A promising approach may be the use of artificially 375 formulated sediments as substrates for culturing benthic invertebrates in the lab (Watzin & Roscigno, 1990). An invertebrate common to the Bering and Chukchi Seas that might be suitable is Ampelisca. Their importance as food sources for many marine mammals makes species from this genus likely candidates for a sediment toxicity test. Until more region-specific test species are available, organisms such as Anemia and Pyrocystis will serve as reliable surrogates. With more developmental work, these two species can be used as part of an integrated ecotoxicological monitoring program that can provide useful information toward establishing baseline conditions for the Bering and Chukchi Seas. The anticipated assaults from oil development can be monitored so that impacts to these ecosystems can be minimized. Special thanks to W. Walker, M. Watzin, A. Alonzo, and J. Johnston for their help and support. 376 Chapter 9 References Azam, F., Fenchel, T., Field, J. G., Gray, J. S., Meyer-Reil, L. A. & Thingstad, F. (1983). The ecological role of water column microbes in the sea. Mar. Ecol. Prog. Scr. 10. 257. Becker. P. R. (1988). Beaufort Sea— Information update. OuterContinental Shelf Environmental Assessment Program, Minerals Management Service, 86-0047, 86 pp. Butler, G. L. (1977). Algae and pesticides. Reskliie Reviews 66, 19. Cairns, J., Jr. & Pratt. J. R. (1987). Ecotoxicological effect indices: A rapidly evolving system. Water Sci. Technol. 19, 1-12. Chapman, P. M. ( 1986). Sediment quality criteria from the sediment quality triad: An example. Environ. Toxicol. Chem. 5, 957-964. Chapman, P. M. & Long, E. R. ( 1983). The use of bioassay as a part of a comprehensive approach to marine pollution assessment. Viewpoint 14, 8 1 -84. Connell, D. W. ( 1987). Ecotoxicology — A framework for the investigations of hazardous chemicals in the environment. Amino. 16. 47-50. Daste. P. H. & Neuville, D. (1974). Toxicity of agricultural pesticides used in marine environments. La Peche Maritime 55, 693. (in French) Egorov, S. N., Korsak, M. N. & Korolenko, M. I. (1984). The influence of some heavy metal ions on primary production and content of hydrocarbons in seawater. Biol. Sci. 5, 60-64. (in Russian) Eppley, R. W. & Peterson, B. J. (1979). Particulate organic matter tlux and planktonic new production in the deep ocean. Nature 238, 677. Federal Register (1985). EPA 40 CFR Part 435, Oil and gas extraction point source category, offshore subcategory; Effluent limitations, guidelines and new source performance standards; Proposed Rule. pp. 34,631-34,635. Fisher. N. S.. Carpenter, E. J., Remsen, C. C. & Wurster, C. F. (1974). Effects of PCB on interspecific competition in natural and gnotobiotic phytoplankton communities in continuous and batch cultures. Microb. Ecol. 1, 39. Flegal, A. R. & Patterson, C. C. ( 1983). Vertical concentration profiles of lead in the central Pacific at 15°N and 20°S. Earth Planet. Sci. Lett. 64, 19. Foster, G. D., Baksi, S. M. & Means. J. C. (1987). Bioaccumulation of trace organic contaminants from sediment by Baltic clams (Macoma halthica) and soft-shell clamsiMyaarenaria). Environ. To.xicol. Chem. 6.969-916. Frost, B. W. (1990). Control of phytoplankton stock and production in the open subarctic Pacific Ocean: SUPER modeling. &«■ (abst.) 71(2), 189. Fuhrman, J. & Azam, F. ( 1982). Thymidine incorporation as a measure of heterotrophic bacterioplankton production in marine surface waters; Evaluation and field results. Mar. Biol. 60. 109-120. Griffiths. R. P., Caldwell, B. A., Broich, W. A. & Morita, R. Y. (1982). The long-term effects of crude oil on microbial processes in sub-arctic marine sediments. Estuarine Coastal Shelf Sci. 15, 183-198. Guillard, R. R. L. & Ryther, J. H. (1962). Studies of marine planktonic diatoms. Can. J. Microbiol. 8, 229-239. Hale, D. A. (ed.) (1987). Chukchi Sea— Information update. OuterContinental Shelf Environmental Assessment Program. Minerals Management Service, 86-0097, 106 pp. Hanson, R. B., Pomeroy, L. R., Blanton, J. O., Biddanda, B. A., Wainwrighl, S., Bi.shop, S. S., Yoder, J. A. & Atkinson, L. P. (1988). Climatological and hydrographic influences on nearshore food webs off the southeastern United States: Bacterioplankton dynamics. Cont. Shelf Res. 8(12), 1321. Hinckley, D. A., Rice, C. & Bidleman, T. (1992). Long-range transport of atmospheric organochlorine pollutants and air-sea exchange of hexachlorocyclohexane. (Subchapter 8. 1. 1. this volume.) Hood, D. W. & Calder, J. A. (1981). Consideration of environmental risks and research opportunities on the eastern Bering Sea shelf. In The Eastern Bering Sea Shelf- Oceanography and Resources. Vol. II (D. W. Hood and J. A. Calder, eds.), pp. 1229-1322. Izrael, Yu. A. (1979). Ecology and Monitoring the State of the Environment, 373 pp. Gidrometeoizdat, Leningrad. (in Russian) Izrael, Yu. A. & Tsyban, A. V. (1986). Scientific Justification for the Integrated Ecological Monitoring Program. Gidrometeoizdat Publishers, Moscow. Izrael, Yu. A. & Tsyban. A. V. (1989). Anthropogenic Ecology of the Ocean. 528 pp. Gidrometeoizdat. Leningrad. (in Russian) Kimball, K. D. & Levin, S. A. ( 1985 ). Limitations of laboratory bioassays: The need for ecosystem-level testing. BioScience 35, 165-171. Korsak, M. N. & Egorov, S. N. (1985). Investigation of the combined effects of some heavy metals on phytoplankton in microecosystems. In Ecological Effects of Ocean Contamination, pp. 64-72. Gidrometeoizdat, Leningrad, (in Russian) Korsak, M. N. & Timoshenkova, N. P. ( 1 990). Ecotoxicological investigations in the Baltic Sea. In Investigations of the Baltic Sea Ecosystem, 3, 47-55. (in Russian) Krynitsky, A. J., Rice, C. P. & Roscigno, P. F. ( 1 992 ). Baseline levels of certain trace metals in sediment and biota ( Subchapter 8. 3. 2, this volume.) Levin, A., Kimball, K. D., McDowell, W. H. & Kimball. S. F. (eds.) (1984). New perspectives in ecotoxicology. Environ. Manage. 8, 375^42. Liftshits, A. V. & Korsak. M. N. (1988). Ecotoxicological screeningof the pelagic ocean. Hydrobiol. J. 24{6), 10-13. (in Russian) Long, E. R. & Chapman, P. M. ( 1985). A sediment quality triad: Measure of sediment contamination, toxicity and infauna community composition in Puget Sound. Mar. Pollut. Bull. 16,405^15. 377 Lyman, J. & Fleming, R. H. (1940). Composition of seawater. J. Mar. Res. 3. 134-139. Maloney, T. E. & Palmer, C. M. (1956). Toxicity of six chemical compounds to thirty cultures of algae. Water Sewage Works 103, 509. Maximov, V. N., Kadomtsev, S. B., Korsak, M. N. & Liftshits, A. V. (1989). Geometrical analysis surface of the impact in ecotoxicological experiments. Proc. USSR Acad. Sci. Ecol. Iss. 4, 42-54. (in Russian) Menzel, D. W., Anderson, J. & Randtke, A. (1970). Marine phytoplankton vary in their response to chlorinated hydrocarbons. Science 167, 17-24. Moore, R. B. & Dorward, D. A. (1968). Accumulation and metabolism of pesticides by algae. / Pycoi 4 (suppl.), 7. (abstr.) Mosser, J. L., Fisher, N. S., Teng, T-C. & Wurster. C. F. (1972). Polychlorinated biphenyls: Toxicity to certain phytoplankters. Science 175, 191. Neulille, D., Daste, P. & Longchamp, R. (1974). Comparative toxicity of diverse pesticides with respect to two species of diatomes used in the oyster-culture. C. R. Acad. Sci. Paris Ser. D. 279, 675. (in French) Nosoz. V. N. &Syrotkina, N. V.(1981 ). The influence of zinc and chromium ions on the phytoplankton community. Hydrobiol.J. 17(4), 42-54. Odum. Y. (1975). Fundamental Basis of Ecology. Mir Publishers, Moscow, 675 pp. (in Russian) Parsons, T. R., Malta, Y. & Lalli, C. M. ( 1984). A Manual of Chemical and Biological Methods for Seawater Analysis. Pergamon Press, New York. Peltier, W. H. & Weber, C. I. (eds.) (1985). Methods for measuring the acute toxicity of effluents to freshwater and marine organisms. 3rd Ed. Environmental Monitoring and Support Laboratory, Cincinnati. Off. Res. Dev., US Environ. Prot. Agency. EPAy600/4-85/013. Persoone, G., Van De Vel, A., Van Steertegem, M. & De Nayer, B. (1989). Predictive value of laboratory tests with aquatic invertebrates: Influence of experimental conditions. Aquat. To.xicol. 14, 149-166. Persoone, G. & Castritsi-Catharios, J. ( 1 989). A simple bioassay with Anemia larvae to determine the acute toxicity of antifouling paints. Water Res. 23, 893-897. Persoone, G. & Wells, P. G. (1987). Artemia in aquatic toxicology: A review. In Artemia Research and its Applications. Vol. I. Morphology, Genetics, Strain Characterization, and Toxicology, pp. 259-275 (P. Sorgeloos, D. A. Bengston, W. Decleir & E. Jaspers, eds.). Universal Press, Wetteren, Belgium. Rice, C. P. & Sikka, H. C. ( 1973). Uptake and metabolism of DDT by six species of marine algae. J. Agric. Food Chem. 21, 148. Rice, C. P., Krynitsky, A. J. & Roscigno, P. F. (1992). Organochlorine contamination sediments, fish, and invertebrates. (Subchapter 8. 1. 3, this volume.) Sambrotto, R. N. & Lorenzen, C. J. (1986). Phytoplankton and primary production in the Gulf of Alaska. In The Gulf of Alaska: Physical Environment and Biological Resources (D. W. Hood & S. T. Zimmerman, eds.) Chap. 9; pp. 249-284. University of Washington Press, Seattle. Sambrotto, R. N., Niebauer, H. J, Goering, J. J., & Iverson, R. L. (1986). The relationship among vertical mixing, nitrate uptake and growth during the spring phytoplankton bloom in the southeast Bering Sea middle shelf. Cont. Shelf Res. 5(1/2), 161. Singh, P. K. ( 1973). Effect of pesticides on blue-green algae. Arch. Mikrobiol. 67, 166. Sodergren, A. (1971). Accumulation and distribution of chlorinated hydrocarbons in cultures of Chlorella pyrenoidosa (Chlorophyceae). Oikos 22, 215. Stiffey, A. V. (1990). Microbiological assay using bioluminescent organism. US Patent — 4, 950, 594 (21 Aug.). Stiffey, A. v.. Blank. D. & Loeb. G. I. (1987). Solid state photometer circuit. US Patent — 4, 689, 305 (25 Aug.). Stiffey, A. V., Blank, D. & Loeb, G. I. ( 1985). An inexpensive photometer. / Chem. Ed. 62, 360-361. Ukeles, R. (1962). Growth of pure cultures of marine phytoplankton in the presence of toxicants. Appl. Microbiol. 10, 532. Vanhaecke, P. & Persoone. G. (1984). The ARC-test: A standardized short-term routine toxicity test with Artemia nauplii. Methodology and evaluation. In Ecoto.xicological Testing for the Marine Environment Vol. 2, pp. 143-151 (G. Persoone, E. Jaspers and C. Claus, eds.). State Univ. Ghent and Inst. Mar Sclent. Res., Bredene, Belgium. Watzin, M. C. & Roscigno, P. F. (1990). Community-level field approach for testing the toxicity of contaminated sediment (Abstract). In Global Environmental Issues — Challenge for the 90's. Society of Environmental Toxicology and Chemistry. Washington, D.C. Wheeler, P. A. & Kirchman, D. L. (1986). Utilization of inorganic nitrogen by bacteria in marine systems. Limnol. Oceanogr. 31, 998. Whitledge, T. E., Malloy, S. C. Patton, C. J. & Wirick. C. D. ( 198 1 ). Automated nutrient analysis in seawater. Tech. Rep. 5 1398. Departmentof Energy and Environment. Brookhaven National Laboratory, Upton, New York. 378 Chapter 10: MARINE BIRDS Editor: CAMERON B. KEPLER 10.1 Water Masses and Seabird Distributions in the Southern Chukchi Sea JONATHAN M. ANDREW* and J. CHRISTOPHER HANEY» 'Regional Office, US Fish & Wildlife Senice, Anchorage. Alaska. USA 'Woods Hole Oceanographic Institution. Woods Hole. Massachusetts. USA Introduction The Bering and Chukchi Seas represent highly strategic territories to the countries at their margins. Fishery stocks, populations of migratory wildlife, mineral resources, pollution control, and navigation through international straits are among the sovereignty and management concerns shared by both the Soviet Union and United States. Given the recent declaration of 200-mile Exclusive Economic Zones and attendant regulation of resource development on outer continental shelves, both countries have a strong basis for mutual cooperation and joint research in these high latitude seas. Seabirds are among the natural resources shared by both countries. Very large populations of murres, puffins, guillemots, auklets, kittiwakes, and other species breed on islands in the northern Bering Sea (e.g., St. Lawrence Island) and within Bering Strait (e.g.. Little Diomede Island) and may forage across jurisdictional boundaries (Sowls et ai. 1978; NOAA, 1988). In fact, the most important offshore foraging sites used by seabirds from these colonies are often unknown because at- sea censusing has been previously limited to the east side of the International Convention Line (cf. Springer et ai. 1989). Recent studies have shown that environmental gradients from east to west across the northern Bering and southern Chukchi Seas have profound consequences for both benthic (Grebmeier et ai. 1988, 1989; Grebmeier & McRoy, 1989) and pelagic food webs (Springer effl/., 1989). Variability in hydrographic regimes is also thought to influence the distribution and species composition of seabird colonies (e.g.. Springer et ai. 1984, 1 987), but no synoptic comparisons of seabirds to water masses and oceanographic properties have been made across either the northern Bering or southern Chukchi Seas. The principal objectives of the Third Joint US-USSR Bering & Chukchi Seas Expedition were to characterize the fundamental oceanographic, hydrochemical and hydrobiological parameters of these marine ecosystems (e.g.. Whitledge et al.. 1988), and to assess their capacity for assimilating marine pollution (I ARPC, 1988). Main scientific tasks included /. collecting biological, chemical, and physical data to provide comprehensive ecological and oceanographic profiles of the Bering and Chukchi Seas; 2. studying the physiological and ecological characteristics of plankton organisms; and 3. as.sessing the ecological health of the Bering Sea. Here we report on marine distributions of seabirds in the southern Chukchi Sea during late summer (August 1988). We interpret our findings within the contexts of /. concurrent oceanographic measurements of both seabird and water mass locations; 2. along- rather than across-shelf variability in seabird abundance; and 3. the affects of colony adjacency and reproductive status in detecting seabird use of water masses. Materials and Methods Study Area The Chukchi Sea ranges from Wrangel Island off northeastern Siberia, USSR, east to Point Barrow, Alaska, and south to Bering Strait (Fig. I). The study area for this cruise extended from Kolyuchin Bay on the Chukchi Peninsula, Soviet Union, northeastward to Cape Lisbume, Alaska, and then south to the strait. The Chukchi Sea continental shelf is uniformly shallow, ranging between 40 and 60 m in depth. Unlike many continental shelves, the Chukchi Shelf is primarily oriented east-west instead of north-south. The relatively deep Barrow and Herald Canyons transect the outer continental shelf margin to the north, and Herald Shoals (20-30 m sill depth) dominates the north-central Chukchi seafioor. This analysis was confined to the southern Chukchi Sea, where bottom slopes are very slight except on immediate approach to land. Fig. 1. Study area and bathymetry in the southern Chukchi Sea. 381 During summer, the Chukchi Sea is supplied with relatively warm water through the Bering Strait which results in ice-free conditions over 50-100% of its area by late summer (Stringer etal., 1980). Three distinct water types that conserve salinity, but not temperature, flow northward through Bering Strait into the Chukchi Sea (Coachman et ai. 1975; Aagaard, 1984; NOAA, 1988). Anadyr water on the west is the most saline (>33 ppt), followed by Bering Shelf water in the center, and finally Alaska Coastal water (<31.5 ppt) on the east. Anadyr water mixes extensively with Bering Shelf water and loses its identity soon after entry into the Chukchi Sea (e.g., Grebmeier etal.. 1989). During its northward flow, Alaska Coastal water is augmented by additional freshwater inputs from Kotezebue Sound. Siberian Coastal water intrudes from the East Siberian Sea along the Siberian coast and is characterized by salinities <32 ppt (Coachman et ai. 1975). The general flow from the strait eventually veers eastward past Pt. Hope, steered in part by bathymetry. Tidal amplitudes are small and do not contribute significantly to water mass movements (NOAA, 1988). Seabird Censuses Seabirds were counted aboard the research vessel (RA') AA"«£/e/?»A' A'o/o/ev between 8 and 15 August 1988. Shipboard counts were conducted along transect lines running along the Chukchi Sea Continental Shelf, generally in east-west directions (Frontispiece). Sixty-two 10-min transect counts were conducted in the southern Chukchi Sea portion of the joint expedition. A total of 129.5 km- was censused at an average ship speed of 15 knots (Table 1 ). Transects were taken while the ship was in motion and used a 300 x 300 m zone (90° sector) extending forward and abeam of the vessel on the side with the best viewing conditions (Tasker et ai. 1984). Ship position (latitude/longitude) was recorded at the beginning and end of each transect count. All birds sitting or fiying within the transect were counted, but sitting and flying birds were recorded separately. Counts were conducted between oceanographic stations by a single observer from the ship's flying bridge 12 m above the ocean surface. Binoculars were frequently used to detect birds missed by the unaided eye. Thick-billed (llria lomvia) and common (U. aalge) murres, jaegers, and small dark alcids could not always be identified to species. All data were logged on standard USFWS project forms. In addition to the transect counts, 18 station counts were obtained while the ship was stopped for oceanographic sampling. Station counts recorded all birds seen within 600 m of the ship during a 15-min period. Ecological research on the RA' Akademik Korolev was undertaken in five ecosystems in the Bering and Chukchi Seas ( Bering Sea Shelf, Bering Sea Slope, Gulf of Anadyr, Chirikov basin, and southern Chukchi Sea). The oceanographic data used in this analysis are from the southern Chukchi Sea, the only region from which we had sufficient seabird transects and station counts. Along the transect lines, the vessel was stopped to deploy instruments for measuring physical and biological attributes of the water at 32 stations (Stations 44-75, Frontispiece ). A CTD hydrocast unit recorded depth, pressure, water temperature, conductivity, salinity, and density (o, ). Vertical cross-section profiles along transect lines were obtained from programs developed at the Institute of Marine Science, University of Alaska, Fairbanks, and Woods Hole Oceanographic Institution. Analysis Relationships of seabirds to water masses were examined by first categorizing all 10- and 15-min counts by the water type in which they occurred. Ship position, sea surface temperature, and salinity were used to place each transect within the proper water mass. Seabird abundances were expressed both as the number km - and hour counted. Numbers of birds per 10-min transect were used as sample units in multiple comparisons (Kruskal-Wallis rank sums analysis) across all water mass types. When there were significant overall differences, individual comparisons between water mass types were made using Mann- Whitney {/-tests. If values of U were outside limits of regular probability tables due to large sample size, the approximate normal deviate Z was used as the test statistic (Snedecor& Cochran, 1980). Zvalueswere corrected for tied groups. Results Water Mass Distrihiitions Three distinct water masses were recorded within the southern Chukchi Sea during August 1988 (Figs. 2-6). We follow previous convention in designating these water mass types (e.g., Coachinan e! ai. 1975; Coachman, 1987). TABLE 1 Allocations of census effort by water mass type: SCW=Siberian Coastal water; BSAW=mixed Bering Shelf-Anadyr water; ACW=Alaska Coastal water. 10-min transect counts 15-min Station Counts Number Total Average Total X area/ Number Total of time speed area transect of time counts (mm) (knots) Range censused counts (niin) sew 23 BSAW 24 ACW 1 5 230 240 150 15.0 15.0 15.0 13-16 48.07 15-16 50.16 15 31.35 2.09 2.09 2.09 7 105 8 120 3 45 38: The water masses were oriented south to north across the Chukchi Shelt'and were not exclusively related to bathymetry, water from Bering Strait progressed northward through the central Chukchi Sea and constituted a tongue of relatively high surface salinity, with less saline water both on the west and east sides (Fig. 2). Fig. 2. Surface honzontaldistnbutionsofsalinity( in parts per thousand: ppti along the southern Chukchi Sea Continental Shelf. Alaska Coastal water (<3 1 .5 ppl) lies to the east of mixed Bering Shelf- Anadyr water 031.5 ppt) which was situated immediately north of Bering Strait. Siberian Coastal water (<3l..'i ppt) lies west of Bering Shelf- Anadyr water between Kolyuchin Bay and Cape Dezhnev on the north coast of the Chukchi Peninsula. Alaska Coastal water ( ACW) occurred in the eastern part of the southern Chukchi continental shelf (Fig. 2). This water mass is characterized by salinities <31.5 ppt, relatively high surface temperatures (>6°C; Figs. 3,4), and a north-south orientation along the coast of western Alaska. The transition between this and the next water mass was weaker than between the other two water masses (cf. Coachman el ciL. 1973). Mixed Bering Shelf-Anadyr water (BSAW; Grebmeier et al.. 1989) was confined to the area immediately north of Bering Strait between the two other water masses and is characterized by salinities in excess of 31.8 ppt (Fig. 2), low surface temperatures of -1 to -i-2°C, and a vertically mixed water column (Figs. 3-6). The contribution of Bering Shelf and Anadyr Waters to the southern Chukchi Shelf is especially evident in Fig. 3, which illustrates a tongue of colder surface water extending northward from Bering Strait into the Chukchi Sea. Also, because isolines of temperature and salinity (Figs. 4,5) were oriented more vertically along the southern (e.g.. Stations 72-75) than along the northern, more stratified sections, the separate identity and lack of lateral exchange of water masses flowing north through the strait is apparent. 60- (» Fig. 3. Surface horizontal distributions of temperature (in X) along the southern Chukchi Sea Continental Shelf. To the east of BSAW and north of the Chukchi Peninsula, Siberian Coastal water (SCW) occurred. This water mass was characterized by very low surface salinities (24-31.5 ppt), medium surface (3-5°C) and low bottom temperatures (-1 to 1 °C ), and a highly stratified water column ( Fig. 6). The bottom salinity in SCW (Fig. 5, top) is also higher than that of water from Bering Strait (Fig. 5, bottom). Siberian Coastal water is thought to intrude eastward from the East Siberian Sea along the Siberian coast (Coachman et al.. 1975). The tongue of SCW during the 8-15 August 1988 cruise of the Akademik Korolev (Fig. 2) extended further east than during the 24 July- 1 August 1972 cruise of the R/V Oshoro Maru (Fig. 72, Coachman t7fl/., 1975). The transition between SCW and BSAW was marked by very steep gradients of temperature and salinity compared to the BSAW-ACW transition. Species Accounts Northern Fulmar (Fi2 birds km') in SCW (Tables 2,3). but this procellariiform also occurred in BSAW and ACW in lesser numbers. Colonies west of Provideniya on the Chukchi Peninsula (D. Siegel-Causey & J. Piatt, personal communication) and at St. Matthew Island in the central northern Bering Sea (Sowls et al., 1978) would be the nearest origins for fulmars in the Chukchi Sea. Both of these colonies are south of Bering Strait (Fig. I ). Short-tailed Shearwater (Puffinus tenuirostris). Short- tailed shearwaters were >50 and >500 times more abundant in SCW than BSAW and ACW, respectively (Table 2). This austral species breeds in New Zealand, southern and eastern Australia, Tasmania, and adjacent islands, migrating to the Bering and Chukchi Seas during the Northern Hemisphere summer (Hunt et al.. 1981 ). High concentrations have been recorded at Aleutian Island passes (e.g., Unimak) during May- June and September-October and northeast of St. Lawrence Island during August-September (NOAA, 1988). 383 Station Station Fig. 4. Vertical cross-section profiles of lemperaturc (in °C) along five west to east transect lines along the southern Chukchi Sea Continental Shelf. Panels are arranged from north (top) lo south (bottom) (cf. Frontispiece). Fig. 5. Vertical cross-.section profiles of salinity (in ppt) along five west to east transect lines along the southern Chukchi Sea Continental Shelf. Panels are arranged from north (top ) to south (bottom ) ( cf. Frontispiece ). Isohales are illustrated in 0.5 ppt. Red Phalarope {Phalaropus fiilicarici). Phalaropes were absent from ACW but were recorded in both BSAW and SCW where they were equally abundant (Table 2). Many of the phalaropes tended to occur either near the boundary between water masses or at locations with steep horizontal gradients in salinity — for example. Stations 60. 70, and 72-73 (cf. Frontispiece, Fig. 2). Little is known about phalarope distributions and autumn staging areas in the western Chukchi Sea. Small flocks of 10-20 individuals were also observed feeding in association with gray whales ( Esch rictius robust us ) . Pomarine Jaeger (Stcrconihus ponutrinus). Based on 10-min transect counts, Pomarine jaegers were most abundant in SCW (Table 2), possibly because this water mass also had large numbers of short-tailed shearwaters that jaegers could exploit t kleptoparasitize ) for food. Jaeger abundances derived from the 15-min station counts (Table 3) were equal across the three water masses. Long-tailed Jaeger (Stercorarius lonsicaudus). Three individuals of this jaeger species occurred in SCW near Station 61 (Frontispiece). Hemn^GuW (Lams argeutatus). Herring Gulls were most abundant in SCW (Tables 2, 3). Although apparently not nesting locally on the Soviet side of the .southern Chukchi Shelf (e.g., NOAA, 1988), herring gulls breed on the Chukchi Peninsula ( AOU, 1 983 ) and at Koozata Lagoon on St. Lawrence Island in the northern Bering Sea (Fay & Cade, 1959; Sowls etcii. 1978). The race that occurs in the southern Chukchi and northern Bering Seas is the darker-mantled Siberian form, L. a. vegac (Grant, 1986). 384 station Depth (m) Fig. 6. Vertical cross-section profiles ol density (in a, units) along five west to east transect lines along the southern Chukchi Sea Continental Shelf. Panels are arranged from north (topi to south (bottom) (cf. Frontispiece). Isopycnals are illustrated m ().!i units of o,. Glaucous Gull (Lams hyperhoreiis). This gull was about equally abundant in SCW and BSAW as recorded by lO-min transects (Table 2). Based on 15-niin station counts (Table 3), it was most abundant in SCW and approximately equally common in BSAW and ACW. The more homogeneous distribution of this species across the three water mass types compared to the herring gull may be due to colony distribution and adjacency. Glaucous gulls nest in small colonies (<100 individuals) from Kolyuchin Bay eastward to capes Serdtse Kamen and Dezhnev on the northern coast of the Chukchi Peninsula, and on the coast of western Alaska from Cape Lisburne south to Kotzebue Sound (NO A A, 1988). Larger colonies (> 1 00 individuals) exist near Cape Thompson and at the Diomede Islands (Sowlsf'/fl/.. 1978: NOAA, 1988). Black-legged Kittiwake jRissa tridactyla). Kittiwakes were more than twice as common in SCW than in BSAW and ACW (Tables 2, 3). Small colonies « 10,000 individuals) are found around the coastline of the entire southern Chukchi Sea, whereas large colonies 010,000 individuals) are restricted to Cape Lisburne, Cape Thompson, and the Diomedes (Sowls etai. 1978; NOAA, 1988). Sabine's Gull (Xema sahini). Small numbers of Sabine's gulls were observed only in SCW and BSAW (Tables 2,3). Arctic Tern {Sterna panidisaea). Ten arctic terns were recorded in SCW near Station 45 (Table 2; Frontispiece). This location is not far from a small breeding colony on Kolyuchin Island (NOAA, 1988) near the western edge of the study area. Common Murre(L'naflfl/,gf ) and Thick-billed Mune(L'nfl lonivia). Abundances of murres showed a trend of increasing abundance from west to east when unidentified individuals and both species were combined (Table 2). Thus, ACW had the highest murre densities: 3.5 birds km - versus 2.6 and 1 .3 birds km ' in BSAW and SCW, respectively. The at-sea abundances parallel the distribution of colonies from which murres probably originate. Only small colonies (< 100,000 individuals) are located on the Soviet (western) side of the Chukchi Sea, whereas two large colonies ( 100,000-1,000,000 individuals) are situated at the eastern end of the study area in Alaska at Cape Lisburne and Cape Thompson (Fig. I: NOAA, 1988:Sowls etal., 1978). Withineach water mass type, there was generally a decrease in murre abundance with increasing distance from land and colony of probable origin. Largest numbers were counted near Stations 49, 50, and 51 (< 1 20 km from the Cape Lisburne colony) and near Stations 60 and 61 (<100 km from colonies at and east of Cape Serdtse Kamen: Fig. I ). KinVitz' ^MurTeleHBraclixrampliitsbrevirosiris). Four of these murrelets were seen together on 1 5 August in BSAW near Station 74 (Frontispiece). Although very uncommon in the Chukchi Sea, this alcid breeds north to Pt. Hope, Alaska, and is casual in northeastern Siberia (AOU, 1983). Parakeet Auklet iCxclorrhxnchu.s psittaciila). Three parakeet auklets were counted between Stations 73 and 74 in BSAW (Frontispiece). This location is <65 km from the closest of several colonies at Cape Dezhnev on the western side of Bering Strait (NOAA, 1988). Least Auklet {Aeihiapusilla). Least auklets were far more abundant in BSAW than SCW and ACW (Table 2). Except for a few individuals near Stations 50, 55, 58, and 6 1 (Frontispiece ), greatest numbers were in the southern portion of the Chukchi Sea between Stations 72 and 75. This latter location is 85-95 km from the closest colony on Little Diomede island, where the breeding population of least auklets numbers just under 1,000.000 birds (Sowls et al.. 1978). Crested Auklet (Aeihia cristatella). Crested auklets occurred t)nly near Station 73 in BSAW (Table 2: Frontispiece). A breeding colony of 140,000 birds is located 85 km south at Little Diomede Island (Sowls ei al.. 1978). Tufted Puffin {Fraiercula cirrhata). Tufted puffins were unrecorded in SCW and on the western side of the southern Chukchi Sea (Tables 2, 3). Single birds only were observed near Stations 49, 50, and 72-75. As few as 100 individuals of this puffin species breed north of Bering Strait, mostly near Capes Lisburne and Thompson in northwestern Alaska (Sowls etai. 1978). 385 TABLE 2 Seahird abundance (density and number per hour) recorded during 10-minute transects in the southern Chukchi Sea by water type. Siberian Bering -Anadyr Alaska Coastal water Coastal water water Number/ Number/ Number/ Number/ Number/ N umber/ km hr km hr km hr 2.1 26.9 0.1 1.5 0.2 2.0 53.3 668.9 1.0 13.0 <0.1 0.8 0.1 1.3 0.4 5.3 0.0 0.0 0.2 2.9 0.0 0.0 0.0 0.0 0.5 6.5 0.1 1.8 <0.l 0.8 <0.1 0.8 0.0 0.0 0.0 0.0 <0.1 1.0 0.0 0.0 0.0 0.0 0.2 3.1 0.0 0.0 0.0 0.0 <0.1 0.5 <0.1 0.3 0.0 0.0 1.4 18.0 0.4 5.0 0.2 2.4 <0.1 0.8 <0.1 0.8 0.0 0.0 0.2 2.6 0.0 0.0 0.0 0.0 0.3 3.7 1.3 16.5 0.3 4.0 0.1 1.6 0.0 0.0 0.0 0.0 0.9 11.5 1.0 12.8 3.2 40.0 r) 0.0 0.0 <0.1 1.0 0.0 0.0 0.0 0.0 <0.1 0.8 0.0 0.0 0.1 1.6 6.8 85.8 0.1 1.2 0.0 0.0 1.1 13.3 0.0 0.0 1.1 13.3 2.6 32.8 0.4 5.2 0.0 0.0 0.1 1.5 <0.1 0.4 <0. 1 0.3 0.2 2.5 0.0 0.0 Northern fulmar iFidmanis glucialis) Short-tailed shearwater (Puffiniis tenuirostris) Red phalarope (.Phalawpus fuUcaria) phalarope sp. (Phalaropus sp.) Pomarine jaeger [Srerconiriiis pomunnus) Long-tailed jaeger (Slercorariiis longicaiuliis) jaeger sp. iSleicorariiis sp.) Herring gull {Uiius argentatus) Glaucous gull (Lcinis hxperboreus) Black-legged kittiwake (Rissa tridaayla) Sabine's gull (Xema sabini) Arctic tern {Stenui paradisaea) Common murre iUria aalge) Thick-billed murre Wria loinvia) murre sp. {Uria sp.) Kittlitz"s murrelet (Brachyramphus hrevirostris) Parakeet auklet (Cyctorrhynchus psittacidu) Least uuklet (Afthia pusilla) Crested auklet [Aelhia crisiatella) auklet sp. {Aelhia sp.) Tufted puffin {Fratercula cirrhata) Horned puffin {.Fralercula conncuUita) TOTAL 60.7 765.3 15.2 194.7 4.5 56.8 Homed Puffin (Fratercula corniculata). Homed puffins were most abundant in BS AW ( Tables 2.3) and were unrecorded in ACW. This puffin was observed near Stations 58.59, 69, 70. and 72-75. All of these locations lie within 90 km of small colonies (5 m) (Ashmole, 1971 ; Sowls etal., 1978; Brown, 1989). Only observations of sitting birds were used for comparison with habitat parameters to provide the most conservative estimate of birds actually using a water type habitat. Both sets of reclassified bird data were examined along with the other biological and physical data to determine the degree of pattern concurrence and differences in average abundance among water types. Hydrographic data were collected with a Sea-Bird(R) CTD at all stations (Coachman & Shigaev, Subchapter 2. 1 , this volume). Seawater density is arguably the most useful physical property for differentiating between water types and masses. Density is primarily a function of salinity in this and other high- latitude baroclinic tlow systems (Royer, 1981). Further, the communities that inhabit these water types differ, reflecting the different sources of these waters, and this information can also beusedinadefmitivemanner(Springer£'r(;/., 1989). Therefore, salinity values and, secondarily, zooplankter distributions were used collectively to delineate differences among water types. Anadyr Stream water was defined as waters having salinities >32.5, BSW salinities were <32.5 and >3 1 .0, and CCW salinity values were <31.0. These definitions approximate those described for water masses by Coachman and Shigaev (Subchapter 2. 1 , this volume) forthiscruise of the RA'AAat/ew/A: Korplev and also take into account water type positions as defined by a more biological parameter, zooplankton communities (see Wyllie Echeverria & McRoy, Subchapter 5.3.1. this volume). The diving depth capabilities of planktivorous seabirds in this region, primarily auklets (Aethia spp. ), are largely unknown. However, water depths throughout the northern Bering Sea Shelf region do not exceed 50 m, and the most conservative prediction of diving capabilities based upon currently available information (Piatt & Nettleship, 1985) puts most of the water column within reach of even the smallest of these birds. Auklets depend heavily on large deep-water copepods advected onto the Bering Sea Shelf via ASW (Springer & Roseneau, 1985). and so they may be able to exploit prey stocks carried in the ASW at depth. For this reason the position of each bird transect was determined with respect to water type distribution at the surface, and distribution of auklets in particular was also compared with water type distributions at each of 5, 10. 15, and 20 m depths. Zooplankton were collected by vertical tow of a 1-m- diameter ring net at all oceanographic stations (Fig. 1). These tows were made from the ocean bottom through the full water column, so the data reported here give an integrated view of zooplankton distribution and abundance, but it is not possible to derive depth of occurrence for any given zooplankter. Evidence from previous oceanographic cruises suggests that the majority of zooplankters concentrate near the pycnocline, which is generally located in the upper 15-20 m in the north Bering Sea in summer (Coachman, 1986; Hunt et al., 1990; ISHTAR group, unpubl. data). Zooplankton samples were preserved at sea in 5% formalin in seawater. In the lab, these samples were sorted by the lowest taxonomic level possible, usually to species (Springer et al., 1989). To compare the distribution and abundance of zooplankton with that of seabirds, only zooplankton species reported to be most important in the diets of planktivorous seabirds are considered here. These are calanoid copepods, including Calamts marshallae, Neocalanus plumchni.'i, N. cristatus. and the euphausiid genus Thyssanoessa (Bedard, 1969; Piatt et al., 1988; Hunt & Harrison, 1990), Because it is unknown which particular zooplankton species birds may have been feeding on during this cruise, if any. these four species will be considered collectively and their quantities summed as an estimate, or index, of available prey. Statistical comparisons were made between categorically classified seabird data and water type position at the surface. Except for the case of auklets as discussed above, more species-specitlc comparisons generally were not often possible because of the high variability associated with at-sea observations. Significant differences in seabird abundances among water types were detected using a series of Kruskal- Wallis nonparametric tests (g.< 0.05) (Zar, 1984). Results Densities of all seabird species combined were not significantly different among water types (p > 0.05. Table 2). However, average densities of surface-feeding birds were significantly more abundant in ASW than BSW or CCW (Fig. 3). Densities of this group of birds were not highest in BSW but significantly different between BSW and CCW. Abundances of shallow-feeding birds, predominantly short- tailed shearwaters and black-legged kittiwakes, were not 391 TABLE 2 Seabird densities (sitting birds/ 10 min transect and birds/km-) in each water type in the northwest Bering Sea during July and August 1988. Seabird Species Anadyr Bering Coastal Stream Shelf Runoff water water water "x X "x X ^ X birds/ birds/ birds/ birds/ birds/ birds/ transect km- transect km- transect km- 49.6 35.7 1 -> 1.6 0.4 0.3 0.3 0.2 0.2 0.1 1.5 1.1 11.2 8.1 0.4 0.3 0.0 0.0 <0.1 <0.1 0.0 0.0 0.0 0.0 0.0 0.0 <0.1 <0.1 0.0 0.0 0.5 0.4 0.0 0.0 1.7 1.3 0.0 0.0 1.4 1.0 25.0 18.0 0.1 0.1 0.0 0.0 0.0 0.0 0.4 0.3 1.4 1.0 12.7 9.2 <0.1 <0.1 <0.1 <0.1 0.0 0.0 4.6 3.3 5.7 4.1 0.3 0.2 1.2 0.8 0.5 0.4 0.0 0.0 0.3 0.2 0.3 0.2 0.0 0.0 0.0 0.0 0.1 0.1 0.1 0.1 0.0 0.0 <0.1 <0.1 0.0 0.0 0.5 0.4 2.8 2.0 37.7 27.2 6.1 4.3 6.5 4.7 0.3 0.2 Northern Fulmar Short-tailed Shearwater Fork-tailed Storm-Petrel Herring Gull Glaucous Gull Black-legged Kittwake Common Murre Thick-hilled Murre murre sp. Parakeet Auklet Least Auklet Crested Auklet auklet sp. Tufted Puffin Homed Puffin total murres total auklets TOTAL 68.2 49.1 41.7 30.: significantly different among the three water types. The trend was for shallow-feeders to be more abundant in CCW than in BSW or ASW (Fig. 3). Deep-feeding bird abundances were significantly higher in CCW than in either ASW or BSW. Bird densities in ASW and BSW were not apparently different, however (Fig. 3). Densities of murres, particularly common murres {Urio aalge). made up the majority of the deep divers in CCW. Plankti vore distributions were significantly different among water types. These were much more abundant in ASW than BSW or CCW, and differences between BSW and CCW could not be detected (Fig. 3). Piscivorous seabirds, predominantly murres and black-legged-kittiwakes {Rissa tridactyla), were also significantly different in abundance among water types. Birds with this prey preference were more abundant in CCW than either ASW or BSW. The latter two water types did not have different bird densities (Fig. 3). Zooplankton (number of zooplankters/km-). or potential prey of planktivores, was more abundant in ASW and BSW than CCW. Between ASW and BSW, zooplankton densities were not significantly different, although abundance in ASW exceeded that of BSW (Fig. 4). Fig. 3. BSW CCW water type 00 80 20 ^M T ■ PLANKTIVORE □ PISCIVORE BSW water tvpe Mean densities (plus/minus one standard error) of seahirds grouped by foraging method (A) and prey preference (B), in three water types in the northwest Bering Sea. ASW = Anadyr Stream water. BSW = Bermg Shelf water, CCW = Chukchi Coastal water. 39" ™ 5 4000 S 9 3000 Fig. 4. Average zooplanklon abundance (mean nuniber/waler lype plus/ minus one standard error) in each of three water types in the northwest Bering Sea. Abbreviations are as indicated in Fig. 3. Auklet distributions (i.e., all auklet species considered collectively) did not differ significantly between ASW and BSW when the distributions of those water types were considered at the surface, and at 5, 10, and 15-m depths, respectively (see Fig. 5). Mean abundances of auklets in both these water types were significantly greater than the mean abundance of auklets in CCW, however. This pattern changed at the 20-m depth; auklets were significantly more abundant in ASW than BSW (Table 3). Chukchi Coastal water was not observed anywhere in the cruise track at the 20-m depth. Discussion hnplicit in all studies of this type are the assumptions that physical features of the pelagic habitat in which birds forage may enhance prey availability and that birds can exploit these features in some way to promote foraging efficiency. In this study, seabirds are unevenly distributed among the water types detected at the surface in the northwest Bering Sea. At these large spatial scales, it appears that seabirds are foraging selectively in water types in which their preferred prey type may be most abundant. Planktivorous birds preferred ASW, which contains the greatest abundance of large oceanic zooplankters. Piscivores, in turn, preferred CCW, which may have the greatest abundances of fish of the three water types. This last conclusion is limited by a lack of information about prey-sized fish distribution in this area at this time, but what data are available suggest that oceanographic conditions in ACW (low salinities, shallow depths, high stability) provide better habitat for small/juvenile fish than BSW or ASW. In that CCW also has these properties, it may also be assumed to be good prey fish habitat. How the different water types affect foraging success via specific foraging strategies requires further investigation. Where AS W is observed at the surface, it may be upwelling zooplankters that would otherwise be unavailable to surface-foragers. Birds employing this strategy are known to congregate at mesoscale features such as convergent fronts that concentrate prey (Brown, 1980). Further, they are among the most mobile and far- ranging foragers of the seabirds included here, and are thereby least limited to a single broad domain. Deep-feeding birds might be expected to be found in water types in which vertical structure concentrates prey and thereby reduces energetic costs of diving (Hunt et ai, 1990). Deep- feeding birds in this study were found in highly-stratified areas where a lens of CCW overlay BSW or ASW. Because deep- feeding birds are exploiting a foraging niche unavailable to surface- or shallow-feeders, their distributions might be related to distributions of preferred subsurface waters. Planktonic prey abundance and distribution can be better assessed than those of fishes with the sampling methods used here, so the relationships between planktivorous, deep-feeding auklets and zooplankton was used to explore this idea. However, when TABLE 3 Auklet abundance ( x /km- ) in each water type in the northwest Bering Sea in July and August 1988. Water mass positions are estimated at five depths: 0, 5, 10, 15 and 20 m. depth Anadyr Stream Bering Shelf Coastal Runoff (m)' water SE X water SE water X SE 0 6.3 2.1 4.4 2.8 0.7 0.7 5 6.3 2.1 4.4 2.8 0.7 0.7 10 6.3 2.1 4.4 2.8 0.7 0.7 15 5.1 1.6 5.0 3.5 1.0 1.0 20* 8.2 3.4 1.3 0.5 -.- ' Water type positions did not differ appreciably at depths above 15 m. * p < 0.05, determined by Kruskall-Wallis test. 393 a. c. BERING SEA ISLANDS ^ ^ -H — I 1 H i h 56 --54 52 175 177 179 179 177 175 173 171 169 167 165 EIW Fig. 5. Dislnbutionul wutci lypesal varlousdcplh^lMnracc/OnKu). 5(b), l(){c), 15(d), and 2()(elm)inthe northwest Bering Sea, Abbreviations are as indieated for Fig. }. 394 planktivorous deep-feeding birds, the auiclets. were considered separately with respect to water type positions at the surface, the pattern was quite different. Aukiets (i.e., least [Aethia pusilla] and crested auklet [A. cristatelUi] abundances combined) were found in the greatest numbers where ASW occurred at depths of at least 20 m. At 15 m or shallower, aukiets did not show apparent preference for either ASW or BSW, the same result reported by Day et al. (in prep.). Results of dietary analyses suggest that diet composition of aukiets does not change much from year to year, in terms of the prey species consumed (Bedard, 1969; Springer & Roseneau. 1985; Piatt el al., 1988; Hunt et al.. 1990). Zooplankton species are not evenly distributed among water types, so aukiets might be expected to select water types that contained their preferred prey. Again, it is assumed that aukiets have access to each of the water-type habitats considered here. Despite their energetically-costly mode of flight, aukiets have been observed feeding in large aggregations at least 1 1 1 km from the nearest colony(Schauer.pcrsonal observation). Most aukiets breeding in the area of this cruise would be able to reach each of these water types within this distance. Based on the results of the zooplankton distribution analysis in this study (see also Springer et al.. 1989). aukiets should occur in greatest abundance in ASW. When water type distribution is examined at 20 m below the surface, aukiets are clearly concentrated in AS W areas. This may be related to concentration of prey at strong property gradients between water types (e.g., halocline, pycnocline). Examination of these data using only surface salinity values obscures this pattern, and no preference between ASW and BSW can be determined. Taken as a whole, these results suggest that prey preference dictates foraging habitat selection by seabirds at macroscales. Foraging method is probably more important in explaining mesoscale variations in seabird distribution. I am grateful to the US Fish and Wildlife Service and the State Committee for Hydrometeorology. USSR, who made the Third Joint US-USSR Bering & Chukchi Seas Expedition possible. Many thanks also to the captain and crew of the Soviet RA' Akademik Korolev, and to J. Andrew. N. Haubenstock. and B. Bergeron, who collected seabird data and zooplankton samples. C. Chu assisted with computer programming. T.WyllieEcheverria assisted with zooplankton sample processing. T. Whitledge provided access to CTD data. This manuscript benefitted from reviews by C. B. Kepler. C. P. McRoy. E. C. Murphy, and J. A, Miller. This project was supported in part by a grant from the National Science Foundation. USA ( DPP-K4-()52S6). This is contribution number 874 of the Institute of Marine Sciences, University of Alaska, Fairbanks. APPENDIX 1 Species Accounts This section summarizes the relative densities of seabirds among water masses at the species level. When possible, information has been provided here regarding locations of nearest known breeding colonies, abundance of North Bering Sea breeding populations, and pertinent foraging habits for each species described. In addition, how each species was reclassified for the analysis of trophic group(s)/water type relationships is noted here. Nineteen seabird species were observed in the study area. Some seabird species were observed in such low numbers that statistical analysis of their habitat preferences was not possible. For this reason, these species are not included in the detailed species-specific densities given in Table 2, but their presence in the cruise track area is noted in this section. Average densities of all seabird species combined were highest in ASW (49.1 birds/km') (Table 2). Areas influenced by CCW had the next highest total densities (30.2 birds/km=), followed by BSW (8.8 birds/knr). All of the locations of colonies of breeding seabirds referred to below are shown in Fig. 1. Northern Fulmar (Fulmaris glacialis). This surface- feeding seabird was found in average densities in ASW, 22 times higher than densities detected in BSW (Table 2). The closest breeding colony of this species is at St. Matthew Island, from which fulmars may tly several hundred kilometers to feed (Sowlsera/., 1978). However, this species is known to forage noctumally, so birds observed by day in the northern Bering Sea could be nonbreeders rather than breeding birds foraging at great distances from their colonies. Short-tailed Shearwater {Puffinus tenuirostris). This species does not breed in the Bering Sea but spends the boreal summer here. This shallow-diving planktivorous species was at least five times more abundant in CCW than in BSW or ASW. Observations were made by J. Andrew during this cruise. Fork-tailed Storm-Petrel (Oceanodroma fiircata). These surface-feeding plankti vores nest mostly in the Aleutian Islands (Sowlser«/., 1978). They are commonly found at sea, north to the latitude of the Pribilof Islands, although there are no reports of nesting there. This species was 28 times more abundant in ASW than in BSW and was absent from CCW. Steller's E\dex (Pohsticta stelleri). Six flying individuals were observed in only one of the transects surveyed, over BSW. Little can be said, therefore, about pelagic habitat preferences of this species. They are noted here because of current interest in the pelagic distribution (largely unknown) of this species. Red Phalarope (Phalaropus fulicaria). This species was seen flying in very low densities (<0. 1 birds/km-) in ASW and BSW. No conclusions can be reached about significant habitat preferences for this species. Results from other studies indicate that mesoscale oceanographic features may be most important in explaining distribution of phalaropes at sea (Brown, 1980). Pomarine Jaeger (5/t'/-cY)nvrHf.s7)w?u»7/i».?). Parasitic Jaeger iS. parasiticus), and Long-tailed Jaeger (5. loneicaiidu.'i). The distribution of these species might be expected to mirror that of fulmars or kittiwakes (Rissa spp. ). which they often parasitize. Observations of jaegers are too limited in this study, however, to draw conclusions about their habitat preferences. Flying jaegers were observed in low numbers in all three water types. Herring Gull (Lams anieutatits) and Glaucous Gull (L. Iixperboreiis). Abundances of the.se two species were too low for determination of habitat preferences (both<0. 1 birds/km-). Only small populations of herring gulls nest in Alaska, with five of the six documented North Bering Sea breeding sites located on St. Lawrence Island. Most of 395 these are pmbably the Siberian race L. argentatus vegae (Sowls etai. 1978). Trukhin and Kosygin ( 1987) recorded numbers of these birds on the order of hundreds to thousands between February and August 1963-65 and 1983-84 in the Gulf of Anadyr. Although they were considering a wide variety of factors influencing distribution (e.g., sea ice. breeding, and nonbreeding periods combined), it may be that this species was not adequately sampled during the study described here or that abundances or distributions of this species within this area are changing through time. Glaucous gulls are relatively more numerous and are not found south of 59°N( Sowls fM/.. 1978). Breeding birds occur on St. Matthew and Hall Islands, St. Lawrence Island, and much of the northwest coast of Alaska, including Norton Sound. Pelagic densities reported here are similar to those found previously for the study area (Trukhin & Kosygin, 1987). Blacklegged Kittiwake (Rissa tridactvla). In Alaska, an abundance of black-legged kittiwakes breed throughout the northern Bering Sea. These breeding populations are estimated to be over 1.3 X 10'' birds (Sowls eft//., 1978). This kittiwake has been classified as a shallow-diving piscivore for this analysis, although they are known to eat crustacean prey as well, in small amounts. This species was found in the greatest density in CCW, at three times the density observed in ASW. In BSW, kittiwakes were not observed on the water or taking prey. Common Murre {Vria aalee) and Thick-billed Murre (U. lomvia). Murres are classified here as deep-diving piscivores, although a small fraction of the thick-hilled murre" s diet may also consist of zooplanktonic crustaceans. Breeding colonies of these birds are widespread throughout islands and coasts of the north Bering Sea: St. Matthew and Hall Islands. Karaginskiya Island, St. Lawrence Island, the Diomede Islands, and coastal cliffs of Alaska and the Chukchi Peninsula all support nesting murres, totalling over 2x10'' birds (Sowls etai., 1978; Gerasimov, 1986; Vyatkin. 1986; Kondratiev & Kitesky, unpubl. data). The two murre species are sometimes difficult to distinguish at sea, so that densities were calculated for unspecified "murres" as well as for each species when available. Common murre density in CCW was 17 times their density in BSW. This species was not observed on the water in ASW. Thick-billed murres were less common in the study area; these birds were found only in ASW in low numbers. The density of murres not distinguished to species followed the general pattern of common murres described above, as did densities of total murres (all murre data considered collectively regardless of species). Pigeon Guillemot ( Cepplnis columha). Only one individual ofthisspecies was seen flying over ASW. No conclusions may be made as to its habitat preferences in this study. Parakeet AukletfCvc/or/'/nvu/H/.v/^.s /?/(/('»/(;). This species breeds on St. Lawrence Island, King Island, the Diomede Islands, and in small numbers at a few points along the mainland Alaska coast where suitable crevices are available (Sowlsffrt/., 1978). It is estimated that 1 x 10' parakeet auklets nest on the southern portions of the Chukchi Peninsula ( Kondratiev & Kitesky, unpubl data). Nesting is also assumed on Karaginsky Island (Gerasimov, 1986). Parakeet auklets were observed in very low densities in BSW and ASW, and they were not found at all in CCW. Crested Auklet (Aethia chstatella). These deep-diving planktivores nest in large numbers on the St. Matthew and Hall Islands, St. Lawrence Island, King Island, and the Diomede Islands. North Bering Sea populations are estimated at 1 x 10* birds. Crested auklets were absent from CCW, and the density found in ASW was about two times that found in BSW. Least Auklet (A. pusilla). Like the other auklet species. Least Auklets prey on zooplankton, primarily crustaceans, and are capable of relatively deep diving. This species could be the most abundant breeding seabird of the north Bering Sea, with breeding populations totalling about 2.3 x 10" (Sowls et ai. 1978). Breeding colonies are located at St. Matthew Island, St. Lawrence Island, King Island, and the Diomede Islands. Densities of least auklets were approximately the same in ASW and BSW, but low in CCW. Auklet species. Small numbers ofauklets observed during this cruise could not be identified to species. Birds in this classification showed the same trends as for the identified auklet species (i.e., absent from CCW and found in similar abundances between ASW and BSW, with the density in ASW only slightly exceeding that of BSW ). Previous work indicates that the absence of auklets from coastal waters (i.e.. ACW) occurs across the north Bering Sea ( Hunt t7 o/. , 1 98 1 ; Day et al. , in prep.). Tufted Puffin jFratercula cirrhata) and Homed Puffin (FnilercuUi conncidata). These two species occurred at very low densities only in BSW, although small breeding colonies, primarily of horned puffins, occur on island and coasts throughout the north Bering Sea. Both species breed in the greatest numbers in the Gulf of Alaska. Other observations (Schauer, unpublished data) east of the Convention Line have shown both species of puffins to be present in significantly higher densities at sea in ACW than in ASW or BSW. Because ACW was not sampled during this study, it is probable that puffins were not present in the cruise track rather than being undersampled. Based upon the low densities reported here, little can be concluded about their habitat preferences in this study area. 396 Chapter 10 References Aagaard, K. ( 1 984 ). Current, CTD. andPressure Measurements in Possible Dispersal Regions of the Chukchi Sea. Final Rep.. OCSEAP, NOAA/BLM. 6 pp. Andrew. J. A. & Haney, J. C. ( 1992). Water types and seabird distributions in the southern Chukchi Sea (Subchapter 10.1. this volume. ) AOU (1983). Checklist of North American Birds. 6th Ed. American Ornithologists' Union, Washington, D.C. Ashmole, N. P. (1971). Seabird ecology and the marine environment. In Avian Biology, Vol. 1 (D. S. Famer & J. R. King, eds. ), pp. 233-286. Academic Press, New York. Atkinson, L. P., Lee, T. N., Blanton, J. O. & Chandler, W. S. (1983). Climatology of the southeastern United States continental shelf waters. J. Geophys. Res. 88, 4705^738. Bedard, J. (1969). Feeding of the least, crested, and parakeet auklets around St. Lawrence Island, Alaska. Can. J. Zool. 47. 1025-1050. Brown. R. G. B. (1980). Seabirds as marine animals. In Behavior of Marine Animals, Vol. 4 (J. Burger. B. J. 011a & H. E. Winn. eds. ). pp. 1-39. Plenum Press. New York, 515 pp. Brown, R. G. B. (1989). Seabirds and the arctic marine environment. In Proc. of the 6th Conf. of the Comite Arctique Intl., 13-15 May 1985 (L. Key & V. Alexander, eds. ), pp. 179-200. E. J. Brill Pubis.. Leiden, 637 pp. Coachman, L. K. ( 1986). Circulation, water types and fluxes on the southeastern Bering Sea shelf. Conl. Shelf Res. 5 (1,2), 23-108. Coachman. L. K. ( 1 987 ). Adveciion andMi.xing on the Bering- Chukchi Shelves. Component A. Advection and mixing of coastal water on high latitude shelves. ISHTAR 1986 Progress Report. VOL. 1. Inst. Mar. Sci.. University of Alaska. Fairbanks. Coachman. L. K.. Aagaard, K. & Tripp, R. B. (1975). Bering Strait: The Regional Physical Oceanography. University of Washington Press, Seattle. Coachman, L. K. & Shigaev. V. V. (1992). Northern Bering- Chukchi Sea ecosystem: The physical basis. (Subchapter 2.1, this volume.) Day. R. H.. McRoy. C. P. & Tripp. R. B. (1990). Macro- and mesoscale distribution of seabirds in the northern Bering Sea, Alaska (in prep). Fay, F. H. & Cade, T. J. (1959). An ecological analysis of the avifauna of St. Lawrence Island, Alaska. Univ. Calif Puhl. Z; situ production. Local maxima of humic acids in other areas were related to freshwater discharges from the Anadyr River and the Yukon River. The organic carbon distribution in sediments indicate that there are several depositional zones in the major basins that were studied. The major total carbon depositions appeared to follow the regions where the major algal blooms occurred. The carbon signatures for these regions were mostly marine rather than terrestrial. Some specific regions of organic matter buildup indicated terrestrial origins, especially near the mouth of the Yukon River. Chemical and isotopic data indicate that terrestrially derived organic matter is transported from the North American continent into the eastern area of the Anadyr-Bering-Chukchi study area, while little Asian-derived terrestrial material is incorporated into the western sediments. Observation of seabird abundance and distribution were compared to the several distinct water masses that existed over the studied regions. Piscivorous birds predominated by 10 to 20 times in the Alaska coastal area and planktivorous birds were by far more numerous in the Anadyr and Bering Central Shelf water masses. There also was a distinct water mass affinity for northern fulmars and short-tailed shearwaters to locate in the Siberian Coastal water, and these were the same species that were dominant in the Bering Shelf- Anadyr waters. For the southern Chukchi Sea Shelf, these same bird species exhibited greater along, as opposed to across, shelf variability in abundance. The densities corresponded well to the locations of distinct water masses in similar zonal patterns. Anthropogenic pollutant impacts on the area were assessed by observing their distributions, degradation processes, and toxic effects. In general, concentrations of chlorinated hydrocarbon pesticides and polychlorinated bipheny Is ( PCB ' s ) were typical of data reported for other nearby arctic ecosystems. Chlorinated hydrocarbons quantified in the atmosphere included hexachlorocyclohexanes (HCH), hexachlorobenzene, toxaphenes. and chlordane. Polychlorinated biphenyls and DDT's were found at excessively high concentrations, suggesting possible contamination from the ship. Detailed studies of the tlux of a- and y-HCH across the air-sea intertace indicated that, in many areas, the predominate flux for the Y isomer was from the air and that there was a net atmospheric loading of this compound into this area. No local sources were apparent. The concentration of DDT in the seawater was lower than the 1984 BERPAC data, although its level of accumulation in the suspended sediment was still very high, as before. In water, the HCH's are the contaminant group of highest concentration (3.44 ng/1), exceeding the concentration of the other chloroorganic pesticides more than 10-fold. The HCH isomer ratio, a-HCH versus y-HCH, indicates their presence is probably due to long-distance atmospheric transport. In biota, PCB's were measured at levels as high as 67.9 ng/g in neuston and 23.9 ng/g in zooplankton. a-HCH concentration ranged from I to 10 ng/g; the isomer concentrations were lower. Chlordanes, DDT. and hexachlorobenzene were present at low concentrations in most samples. Toxaphene was measured in biota for the first time in these seas. Residues were highest in fish at 1 0.8 ng/g. Sediments had low to nondetectable residues of most compounds analyzed. The HCH's {a, p. and y isomers) displayed behavior that was different from the other measured organochlorines ( OC s ). Global behavior of these compounds in the world's oceans indicates that higher levels tend to occur in colder waters of the poles rather than equatorial waters, which are geographically closer to the areas of their major use. It has been postulated that the globe may function as a giant distillation device, driving them into the air near the equator where they eventually distill into the cooler waters at the poles. In support of this theory, it was observed that the water concentrations for the HCH isomers did indeed exhibit a gradient for higher water concentration with increasing latitude; this relationship was strongest for the P-HCH isomer. The HCH"s also bioaccumulated to a lesser extent than the other OC"s in this system, e.g., bioaccumulation factors for HCH of 5.8 X 10Sersus6.3 x lOM'orthe sum of DDT residues in fish tissue;thisappearstorelatetotheirrelatively low lipid solubility. 402 Aliphatic and aromatic petroleum hydrocarbons were ubiquitous in the sediment from the study area. Generally, hydrocarbon concentrations were low and similar to previous reports. The occurrence of high fluorescence intensity and R ratio values and GC-derived indicators suggests the presence of microseepage at several locations; this implies that underlying petroleum deposits may exist. Low level polyaromatic hydrocarbon (PAH) concentrations (<100 ppb) appear to be related to combustion sources. Specific studies on benzo(a)pyrene (BaP) distribution were conducted, with the assumption that BaP was a good model compound for the other PAH's in the system. The spatial and vertical distribution of BaP in the water of the Bering Sea was relatively uniform, having an average value of 3.5 ng/1. Similar concentrations were observed in previous collections from these areas in 1981 and 1984. A relatively high BaP content was recorded in the Chirikov basin. Benzo(a)pyrene concentrations in sea ice samples averaged about 15 ng/1; in bottom sediments it was 0.7 to 1.7 |ig/kg dry wt. Benzo(a)pyrene concentrations in plankton and neuston. respectively, ranged from 0.2 to 10.0 and 0.6 to 10.0 )ag/kg dry wt. The concentration of BaP in benthic organisms ranged from 0.05 to 13.0 |ig/kg on a dry weight basis. Mixed PAH's were specifically characterized in several compartments of the system. In the water, bottom sediments, suspended sediment and biota of the Bering and Chukchi Seas, 10 PAH's were identified, of which eight are carcinogenic and three of these, benzo(b)fluoranthene, benzo(k)fluoranthene, and BaP, are highly carcinogenic. In the surface water layer, BaP and pyrene prevailed. The overall concentration ip the surface water layers did not exceed 5.1 ng/1, but in the near- bottom layer it reached 24 ng/1. The total concentration of PAH's in the suspended matter reached 1 1.2 ng/g. The total concentration of PAH's in the plankton varied widely (12 to 677 |ig/kg) and for the neuston ranged from 20 to 1 88 |ig/kg on a dry wt. basis. The first data for heavy metals for this area were recorded on this expedition. Concentrations of copper in the water varied from 0.0 1 to 0.46 |ig/l in the open areas of the Bering Sea with an average value 0.08 )ig/l. Shallow-water stations demonstrated a direct relation between copper concentration in water and bottom sediments. The other heavy metal water concentrations were as follows: cadmium ranged from <0.01 to 0. 1 3 |ig/l; manganese did not exceed 0.04 Hg/1; zinc varied from <0.01 to 3.67 )ag/l; and lead varied from <0.01 to 1 .03 |ig/l. In the sediment, the metals investigated (As, Cd, Co, Cu. Pb, Mn, and Hg), with the exception of mercury, were detected in all of the surficial samples (0-2 cm). The concentrations of cadmium, cobalt, lead, mercury, and arsenic appeared to be higher in the shelf areas. Downward fiuxes of planktonic organisms and biogenic debris aie likely sources. Arsenic and cadmium were elevated in most of the marine biota. Tendencies for bioaccumulation rather than localized pollution appear to be the cause. The average concentration of Cs'" for the entire area was 2.4 Bq/m'. The vertical distribution of Cs'" in the Bering Sea was homogeneous, but for the Chukchi Sea it was characterized by an elevated concentration in the bottom layers (ranging from 2.5 to 5.5 Bq/m') and an overall average of 3.1 Bq/m\ The observed homogeneity of the Cs' " indicates the lack of local input of this material. The maximum possible contribution of "Chernobyl's" Cs'" did not exceed 6%. Microbial degradation of many of the PCB congeners ( 1 9 of 70 that were added) was observed. Of these 19 congeners, the dichlorobiphenyl homologs were degraded the fastest, 95 to 100'?^^, and the trichloro homologs next, 64 to 66%, then the tetra's, 10 to 58% and the penta's at 36 to 44%. The hexachlorobiphenyls (HCB's) were degraded only slightly, 7%. With photochemical degradation of PCB' s in seawater, it was found that those congeners of the PCB mixture that did not undergo microbial transformation were often more susceptible to photochemical decomposition. Hexachlorobiphenyls and higher-chlorinated compounds did not undergo any reaction. The photochemical degradation proceeded with direct dechlorination accompanied by isomerization and condensation. The rate of the reaction depends on the molecular configuration, with locations 2,2' or 4,4' favoring photochemical attack. Overall rates of photochemical degradation were slower than the rates for microbial breakdown. Thus microbial breakdown is probably more important to the removal of PCB's than are photochemical processes. It was also determined that the presence of PAH" s could inhibit the photochemical degradation processes by 10%. Microbial degradation experiments with BaP showed that pelagic microflora of this region can transform between 8 and 45 percent/time of the total concentration of BaP. Maximum rates were observed in the Gulf of Anadyr, at the North Polygon, and in the southwest Chukchi Sea. In 21 -days of incubation, 84% of the added BaP was destroyed. The photochemical trans fnrmation is described by a formal first- order kinetic equation. The rate constant values was 0.69 h. Based on relative rates of reaction for microbial versus photochemical breakdown of BaP, photoxidation shares in importance with microbial processes. Natural populations of phyto-, microzoo-, and, bacterioplankton were tested for their susceptibility to some representative natural contaminants (BaP, PCB' s, Cu, and Cd). Primary productivity, bacterial respiration, and cell growth were monitored. Susceptibility was found to vary with pollutant type, collection location, and with the endpoint being monitored. The range of toxicity from the most toxic to the least were as follows: BaP.Cu, PCB.andCd. For BaP, the range of LD,„ to phytoplankton wasO. 1 to 10 |ig/l for primary productivity and for microzooplankton, 0.05 to 7 |ig/l for cell growth. Bacterioplankton had a higher tolerance for all the chemicals than the phytoplankton or microzooplankton, and in some cases their activity was stimulated by the toxicants. This behavior was believed to be an indirect effect caused by increased organic matter resulting from the death of the other organisms in the mixed cultures. Chukchi communities were found to be more sensitive than the Bering Sea organisms to BaP and PCB but less sensitive to Cu and Cd. Characterization of an area of low resistance near St. Lawrence Island agreed with similar findings in 1984 for this area. Comparing the 403 critical C' centration values in the Bering-Chukchi Sea to those foi the Baltic Sea, a highly polluted region, it was found that the Baltic was more susceptible to PCB's and BaP but slightly less susceptible to Cu and Cd. For the Bering and Chukchi Seas, BaP and Cu are the two pollutants whose critical concentration levels approached the natural levels that were found for this region; therefore, these pollutants may be having an impact in this region. Toxicity of a- and y-HCH to natural communities of microplankton were tested. At concentrations from 80 to 100 ng/1, distinct effects were observed on the ambient ammonium pool and '''N ammonium uptake rates, both of which increased in the experimental containers. Bacterial activity per cell increased in the oceanic experiments and decreased in the shelf experiment. These tests indicate that HCH has the capability of altering plankton nitrogen cycling in open ocean systems. A sediment bioassay technique was employed to examine the toxic potential of sediment collected from several regions throughout the study area. Standard single species test protocols were carried out employing Artew/a salina (brine shrimp), and a dinoflagellate, Pyrocystis lonula. No acute effects were observed. These first time tests provided benchmark values that will be useful to future studies monitoring the status of these waters. 404 Conclusions The Third Joint US-USSR Bering & Chukchi Seas Expedition was very productive. It provided new information and improved data sets to enable better understanding of the processes that are occurring in these subpolar-polar regions. Several measures of biological activity confirmed that the summertime productivity here is extremely high, matching some of the highest natural biological activity in the world. As expected, the activity was also quite variable. This variability was caused by several interacting factors. The most dominant factor for this system is the upwelling of nutrient-rich deep current waters that takes place predominantly on the northern Bering Sea Shelf and within and the Chirikov basin. Some representative high values of biological activity that were measured are as follows: 800,000 cells/ml and 18 |ig C/1 for bacteria for the northern Bering Sea; bacterial destruction rates of 107 |ig C/l/d in the Bering Sea; 1,800 mg C/mVd of carbon fixation in the Chirikov basin; phytoplankton counts between 500 and 1 ,700 cells/ml in the Chirikov basin; average biomass of 40 g wet weight/m- for microzooplankton in the Chirikov basin; and benthic biomass in excess of 400-500 g/m- in productive areas. As with previous BERPAC expeditions, the intricate balance of numerous processes working together was verified. A modeling effort revealed the obvious importance of seasonality to regulating this biological activity but it also demonstrated the importance of taking a more holistic approach to future studies. Plans for future modeling are being built around carbon cycling. Carbon is also central to the problems involved with global climate; therefore, it is important to understand more fully the role of carbon processes that are taking place in the Bering-Chukchi Seas ecosystem. Initial data were accumulated on the carbon budget of this system. As a likely carbon sink, this area has an important role in minimizing CO, increase worldwide, especially since increasing CO, may be the single most important factor leading to global warming. The estimated flux of dissolved carbon to the Chukchi Sea-Arctic Ocean amounted to 0.82 x 10" metric tons per year. A significant portion of this carbon likely finds its way to the deeper waters of the Arctic Ocean and eventually may be incorporated into the North Atlantic bottom water. Both of these avenues would act as a sink for greenhouse gas. In addition to its significant impact on the carbon budget, the Bering and Chukchi Seas area also plays a critical role in global climate processes because of the major northward current flow that arrives from the deep Pacific and that is part of the global current that has a central role in regulating the world's climate. This oceanic current is largely responsible for the high productivity of the Bering-Chukchi region and thus, the fisheries and economy of the area are intimately linked to this system. Achieving a better understanding of this current flow and its link to the biology of this system is therefore of extreme importance. The expedition provided further evidence to show that there is still much about the processes taking place in this ecosystem that is only poorly known. For example, using observations from the Gulf of Anadyr and along the Chukchi Peninsula, it was possible to confirm the hypothesis about the current entering the Gulf of Anadyr with a large quantity of nutrients to produce production-deposition centers in the Gulf of Anadyr and Chirikov basin. Also, improved access to areas in the Chukchi allowed di.scovery of many new features about this system. For example, evidence was found for a previously unreported southerly flow of nutrient- and salt-rich water flowing southward along the Siberian coast and merging with the northerly flowing Bering Strait water. Also, many zonal current patterns were identified in the Chukchi basin that had major effects on the biology of the system — for instance, bird sightings, optical measurements, and Cs'" concentration profiles. Considering the fact that such an intense period of biological activity is compressed into the relatively short ice-free period in this region, there is a great deal of concern that disruptions, even though relatively slight, may have profound effects on the ecosystem components and functions. Anthropogenic influences were one of the effects that were studied. Monitoring at specific sites provided information for long-term assessments. With benzo(a)pyrene (BaP) and polychlorinated biphenyls (PCB's), the concentration levels have remained relatively stable since the 1981 and 1984 BERPAC cruises; for DDT, the levels have declined. The absolute abundance of bacterioplankton has increased since the summers of 1 98 1 and 1 984, and for this expedition the indices for microbial cenoses were five times higher than they were in 1984. Indirect evidence of an anthropogenic impact is indicated by the fact that species that can tolerate and metabolize certain pollutants were isolated from these regions. These species also appeared to have increased in abundance over the 1984 levels. In toxicity tests with mixed populations of pelagic flora, harmful effects were observed with BaP and copper at LD,^ values as low as 2 ppm. These concentrations are approached by the natural levels measured in this region. Representatives of several taxonomic groups of bacteria from the region were isolated that had the potential to produce products with mutagenic or genotoxic ( RN A damaging ) effects. Fortunately, for the present, expression of this trait is unlikely, since factors leading to the expression (i.e., extreme anthropogenic pressures or dense bacterial abundance) do not presently exist in the Bering- Chukchi Seas ecosystem, although the fact that the potential is there is certainly cause for concern. Several organic contaminants were measured for the first time in these areas. Among these were observations of high levels of the hexachlorocyclohexane ( HCH ) class of compounds, with an average concentration in water of 3.44 ng/1, and toxaphenes. Also, chlordanes were measured in most samples 405 (e.g., atmosphere, water, biota [plankton, benthos and fish], sediment, and suspended matter). The levels of these organochlorines were typical ofthose found in other neighboring arctic areas, which indicates that there are no local .sources of contamination. One especially interesting observation concerning the levels of HCH" s in surface water was a suggestion of an increasing gradient of concentration with increase in latitude. This supports a theory that these compounds are released into the atmosphere from warm seawater near the equator, and they condense in the colder waters at the poles. There was also evidence, from careful studies of the equilibrium partitioning of the a and y isomers at the air-water interface, that the present levels of the y isomer (Lindane) was on the increase in the Bering-Chukchi Sea area. Trace metal concentrations were measured for the first time in this area. Levels were typical of pristine areas, and no local sources were indicated. Cadmium, however, may require future study, since biomagnification to moderate levels was noted in some of the biota. Microbial degradation of selected congeners of PCB was observed using laboratory incubations of isolates from the region. Rates under these conditions were most rapid for the lower chlorinated homologs, i.e., 95 to \00'7c reduction of the dichlorobiphenyls in 20 days; and less for each succeeding increase in chlorine number, with only 7% reduction of some of the hexachlorobiphenyl htimologs. The activities also varied with the structural position of the chlorines. Studies of photochemical degradation of PCB in in situ tests indicated that the rates for photooxidati ve breakdown were much slower than microbial degradation rates. However, many of the congeners resisting microbial breakdown were degraded in the photochemical tests. In similar tests with BaP, it was found that the rates for BaP degradation by microbial action were comparable to the rates for photochemical decay. These tests demonstrate that even in ecosystems such as the easily damaged and cold waters of the Bering-Chukchi Sea possess the capability to cleanse themselves of man-made pollutants. Several interesting findings emerged from the benthic studies. There were several sites where evidence for petroleum seepage was observed. This confirms the possibility that there may be underlying petroleum deposits in the area. Based on isotope and carbon data from the bottom, it was noted that there is a gradual east to west gradient and high to low concentration of terrigenous source carbon across the areas of each of the major basins. The evidence suggests that most of the land- based carbon is supplied from the Alaskan coastline to these major basins. Contour plots of dissolvedhumics in surface water samples indicated that the maximum levels were often displaced from the areas where actual algal blooms were occurring. This suggests that monitoring for these resistant forms of dissolved organic matter might provide a means to measure the locations and source strengths of previous blooms. 406 Appendix A Participants of the Third Joint US-USSR Bering - Chukchi Seas Expedition, Summer 1988. Tsyban, A. V. * Volodkovich, Y. L, * Roscigno, P. F. * Whitledge. T. E. * Rostovtsev, O. A. Nelepov, Y. N. Vaytekaya, Y. I. Petrovskaya, S. V. Microbiology and Nutrient Working Group Panov. G. V. * Whitledge, T. E Barinova, S. P. Gorelkin, M. 1. Hanson, R. B. Kudryatsev, V. Mamaev, V. O Marchenko, A. Robertson, C. Veidt, D. * Yatsuk, V. Group Leader Group Leader M. USSR Chief Scientist USSR Asst. Chief Scientist US Co-Chief Scientist US Co-Chief Scientist Captain of the RfV Akademik Korolev Asst. to the Captain on Scientific Affairs Scientific Secretary Interpreter Bacterial degradation of pollutants Nutrient chemistry Microorganism indicators Nutrient chemistry Bacterial production Bacterial production Numbers and biomass of microorganisms Technician Bacterial production Nutrient chemistry Hydrochemistry Biogeochemical Cycles of Pollutants Worliing Group Chemyak, S. M. Rice, C. P. Belyaeva, O. L. * Hinckley, D. A. Irha, N. 1. Kolobova. T. P. Krynitsky, A. J. Pershina, I. V. Roscigno, P. R. * Urbas, E. Vronskaya, V. M. Group Leader Group Leader Chlorinated hydrocarbons Chlorinated hydrocarbons Polyaromatic hydrocarbons Chlorinated hydrocarbon Photochemical oxidation of PAH's Trace metals Trace metals Dissolved organic matter Sediment toxicology Photochemical oxidation of PAH's Pollutants in biota Physical Oceanography Working Group Amos, A. F. Gis, S. Shigaev, V. V. Bogarev, S. Coachman, L. K. Drakov, S.N. Kumeisha, A. A. Lavender, M. Lukin, A. E. Group Leader Group Leader Group Leader Conductivity /temperature/depth Hydrology, currents Conductivity/temperature/depth, currents Hydrological oceanography Physical oceanography Vertical profiles Hydrooptics Conductivity /temperature/depth, currents Hydrooptics 407 Benthos, Birds, and Mammals Working Group Grebmeier, J. M. Koltun. V. M. Andrew, J. M. Sirenko, B. I. Group Leader Group Leader Benthic carbon cycling Benthos Sea birds, mammals Macro-benthos Plankton, Neuston, Primary Production, Pigments Working Group Korsak, M. N. * Zeeman, S. I. * Alexandrov, B. G. Bergeron. B. Haubenstock. N. Holmes, G. Korzhikov, 1. Kulikov, A. S. Levina, O. Mamaeva, N. V. Polishchuk, L. N. Robie, W. S. Sambrotto, R. N. * Ventsel, M. V. Wright, T. Group Leader Group Leader Primary production, nutrient modeling Primary production Neuston Chlorophyll, zooplankton Chlorophyll, zooplankton Phytoplankton, C/N Primary production Mesozooplankton Microzooplankton Microzooplankton Biogeography of zooneuston Chlorophyll Phytoplankton, '^N production Phytoplankton Sediment hydrocarbons, phytoplankton pigments Sedimentation and Natural Isotopes Working Group Behrens. W. Glebov. B. V. Adkisson, D. Medinets, V. I. Soloviev, V. G. Group Leader Group Leader Natural isotopes in sediments Biosedimentation Sediment hydrocarbons, phytoplankton pigments Biosedimentation Biosedimentation *_ Also participated in the Second Joint US-USSR Expedition to the Bering Sea, Summer 1984. Soviet Participants: Alexandrov, Boris G. Microbiologist Junior Scientist, Institute of Biology of the South Seas & Academy of Sciences of LIkranian SSR, Odessa Branch 37 Pushkinskaya Street, 27001 1 Odessa,UkSSR Barinova, Svetlana P. Microbiologist Leading Engineer, Institute of Global Climate and Ecology. USSR State Committee for Hydronieteorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR 408 Belyaeva, Olga L. Hydrobiologist Junior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Chemyak, Sergei M. Chemist Senior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Drakov, Sergei N. Hydrobiologist Leading Designer, Institute of Physics & Academy of Sciences, Beleorousskoi SSR Leninsky Prospekt, 70 Minsk, BSSR 220602 Irha, Natalya I. Organic Chemist Scientist, Institute of Chemistry & Academy of Sciences, Estonia SSR Akademia Teye Street, 15 Tallin, ESSR 200108 Kolobova, Tatiana P. Analytical Chemist Senior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Koltun, Vladimir M. Hydrobiologist Department Head and Leading Scientist, Zoological Institute & USSR Academy of Sciences Universitetskaya Street, I Leningrad. USSR 199034 Korsak, Mikhail N. Hydrobiologist Senior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR 409 Korzhikov, Igor A. Hydrobiologist Junior Scientist. Far Eastern Regional Research Institute of Goskomgidromet USSR 24 Dzerjinskiy Street. 690600 Vladivostok, USSR Kudryatsev. Vassiliy Microbiologist Senior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Kulikov, Andrey S. Hydrobiologist Junior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Kumeisha, Alexander A. Hydrooptician Senior Scientist, Institute of Physics & Academy of Sciences, Beleorousskoi SSR Leninsky Prospekt, 70 Minsk, BSSR 220602 Levina. Olga N. Lukin, Alexander E. Hydrobiologist Engineer, Southern Division of the Oceanographic Institute & Academy of Sciences Gelendzhik 7,353470 Oceanologiya, USSR Hydrooptician Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Mamaev, Vladimir O. Microbiologist Post Graduate Student, Institute of Global Climate and Ecology. USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street. 107258 Moscow, USSR 410 Mamaeva, Nila V. Protozoologist Senior Scientist, Southern Division of the Oceanographic Institute of the USSR & Academy of Sciences Gelendzhik 7,353470 Oceanologiya, USSR Marchenko, Alexander S. Hydrobiologist Senior Engineer, Institute of Biology of the South Seas & Academy of Sciences of Ukrainian SSR, Odessa Branch 37 Pushkinskaya Street, 27001 1 Odessa, UkSSR Medinets, Vladimir I. Hydrobiologist Engineer, Odessa Dept. of the State Oceanographic Institute Goskomgidromet, USSR Proletarski Boulevard, 89 Odessa, UkSSR 15270015 Nelepov, Yeugeniy N, Far Eastern Regional Research Institute of Goskomgidromet of USSR 24 Dzerjinskiy Street, 690600 Vladivostok, USSR Panov, Gennadiy V. Microbiologist Senior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Pershina, Irina V. Analytical Chemist Junior Scientist, Institute of Global Climate and Ecology. USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Petrovskaya, Svetlana Institute of Global Climate and Ecology. USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Polishchuk, Leonid N. Hydrobiologist Senior Scientist, Institute of Biology of South Seas & Academy of Sciences of Ukranian SSR. Odessa Branch 37 Pushkinskaya Street. 27001 1 Odessa. UkSSR 411 Ros» . tsev, Oleg A. Far Eastern Regional Research Institute of Goskomgidromet of USSR 24 Dzerjinskiy Street, 690600 Vladivostok. USSR Shigaev, Viktor V. Oceanographer Senior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Sirenko, Boris I. Hydrobiologist Senior Scientist, Zoological Institute & USSR Academy of Sciences Universitetskaya Street, I Leningrad, USSR 199034 Tsyban, Alia V. Chief Scientist Professor of Ecology and Deputy Director, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences 12, Morozov Street, 123376 Moscow, USSR Urbas, Eha R. Organic Chemist Scientist, Institute of Chemistry & Academy of Sciences, Estonia SSR Akademia Teye Street, 15 Tallin, ESSR 200108 Vaytekaya, Yanina I. Hydrochemist Engineer, Hydrometeorological Observatory of Klaipeda Board of Hydrometeorology of Lithuania Goskomgidromet of USSR Taikos Street, 26, 235800 Klaipeda, LSSR Ventsel, Mikhail V. Hydrobiologist Junior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR Volodkovich, Yuriy L. Hydrobiologist Senior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR 412 Vronskaya, Valeriya M. Hydrobiologist Junior Scientist, Institute of Global Climate and Ecology, USSR State Committee for Hydrometeorology & Academy of Sciences Glebovskaya Street, 107258 Moscow, USSR American Participants: Andrew, Jonathan Wildlife Biologist US Fish and Wildlife Service Santa Ana/Rio Grande Valley National Wildlife Refuge Route 2, Box 202A Alamo, Texas 78516 Amos, Anthony Physical Oceanographer, Ph. D. Marine Science Institute University of Texas P.O. Box 1267 Port Aransas, Texas 78373 Adkisson, Daniel L. Geological Oceanographer P. O. Box 1 53 Bass Harbor, Maine 04653 Behrens, E. William Research Chemist, Ph. D. Institute for Geophysics University of Texas 8701 North Mopac Boulevard Austin, Texas 78759 Bergeron, Beth Research Chemist Institute of Marine Science University of Alaska Fairbanks, Alaska 99775 Coachman, Lawrence K. Physical Oceanographer, Ph. D. School of Oceanography University of Washington Seattle, Washington 98195 Grebmeier, Jacqueline Biological Oceanographer, Ph. D. Graduate Program in Ecology 108 Hoskins University of Tennessee Knoxville, Tennessee 37996-1 191 Haubenstock, Norma Research Chemist Institute of Marine Science University of Alaska Fairbanks, Alaska 99775-1080 413 Hanson, Roger B. Biological Oceanographer, Ph. D. Skidaway Institute of Oceanography P.O.Box 13687 Savannah, Georgia 31416 Hinckley, Daniel Chemist, Ph. D. EA Engineering, Science and Technology 11019 McCormick Hunt Valley, Maryland 21031 Holmes, George Research Assistant Institute of Marine Science University of Alaska Fairbanks, Alaska 99775 Krynitsky, Alexander J. Chemist US Environmental Protection Agency Analytical Chemistry Group Beltsville, Maryland 20705 Lavender, Margaret Physical Oceanographer School of Oceanography University of Washington Seattle, Washington 98195 Rice, Clifford P. Research Chemist, Ph. D. Patuxent Wildlife Research Center US Fish and Wildlife Service Laurel, Maryland 20708 Robie, William Research Assistant Institute of Marine Science University of Alaska Fairbanks, Alaska 99775 Robertson, Charles Research Assistant Skidaway Institute of Oceanography P.O. Box 13687 Savannah, Georgia 31416 Roscigno, Pasquale F. Ecologist, Ph. D. National Wetlands Research Center US Fish and Wildlife Service NASA-Slidell Computer Complex 1010 Cause Boulevard Slidell, Louisiana 70458 Sambrotto, Raymond Biological Oceanographer, Ph. D. Lamont-Doherty Geological Observatory Columbia University Palisades, New York 10964 Veidt, Denise Research Assistant 39 Franklin Avenue Mastic, New York 11950 414 Whitledge, Terry E. Chemical Oceanographer, Ph. D. Marine Science Institute University of Texas P.O.Box 1267 Port Aransas, Texas 78383 Wright, Thomas Research Assistant Geochemical and Environmental Research Group Texas A&M University 10 South Graham Road College Station, Texas 77840 Zeeman, Stephen I. Biological Oceanographer, Ph. D. University of New England (Maine) 1 1 Hills Beach Road Biddeford, Maine 04005 415 ,^^^' C.N^ ) ^^M^mw^m