GULF RESEARCH REPORTS Vol. 6, No. 3 December 1979 ISSN: 0072-9027 Published by the GULF COAST RESEARCH LABORATORY Ocean Springs, Mississippi Gulf Research Reports Volume 6 | Issue 3 January 1979 Activities of the Gulf Coast Research Laboratory During Fiscal Year 1 978-79: A Summary Report Harold D. Howse Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.17 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Recommended Citation Howse, H. D. 1979. Activities of the Gulf Coast Research Laboratory During Fiscal Year 1978-79: A Summary Report. Gulf Research Reports 6 (3): 317-339. Retrieved from http:// aquila.usm.edu/gcr/vol6/iss3/17 This Editorial is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua. Cromwell(o)usm.edu. Gulf Research Reports, VoL 6, No. 3, 317 339, 1979. ACTIVITIES OF THE GULF COAST RESEARCH LABORATORY DURING FISCAL YEAR 1978-79: A SUMMARY REPORT HAROLD D. HOWSE Director , Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ADMINISTRATION Construction of a new facility, the Toxicology Building, was initiated and completed on the main campus of the Gulf Coast Research Laboratory (GCRL) during the year. The building design was based in part on the Environmental Protection Agency (F.PA) Toxicology Laboratory, Gulf Breeze, Florida, and the Bionomic Toxicology Laboratory at Pensacola, Florida. The building, designed and constructed at a cost to the Laboratory of $230,000, contains about 3,700 sq. ft. on three levels, and provides separate areas for maintaining stock experimental animals, algal culturing, bioassaying and storage. The Laboratory senior staff constitutes an advisory council that reviews toxicological research proposals, con tributes to the experimental design and, when applicable, participates in the studies. The annual operational budget consisted of $2,100,000 in State-appropriated funds, $1,140,226 in sponsored research and auxiliary funds, and $25,000 in Library Improvement Funds allocated by the 1978 State Legislature. BOA T OPERA TfONS The boats used to provide essential services include the 65-foot R/V GULF RESEARCHER, used in both the Laboratory’s research and educational programs; the 38- foot steel trawler HERMES, used principally in the educa- tional program; three diesel-powered cabin workboats; and some half-do2en Boston Whalers and other miscellaneous smaller craft powered by gasoline motors. The larger vessels are operated by six full-time boatmen, two of whom are licensed Masters for vessels of up to 100 gross tons. The Boston Whalers and other miscellaneous smaller boats are operated by scientists and technicians to meet the needs of some Laboratory research projects. During the year ended June 30, 1979, R/V GULF RESEARCHER was at sea for 89 days and 39 nights. The HERMES spent 50 days at sea and the smaller boats made innumerable trips over the same period. RESEARCH ANAL YTICAL CHENUSTR Y SECTION, Dr. Thomas F. Lytle-, Head Heavy Metals in St. Louis Bay (Funded by E. I. duPont de Nemours & Company, Inc. [Du PontJ): Because heavy metals pose a potential threat to estuarine waters whether coastal areas arc developed industrially or residentially, an assessment of heavy metals has been conducted in St. Louis Bay where very little of either type development exists. Heavy metals have been examined in as many ecological components of the bay as possible. Of primary concern to those interested in discharge limitations is the level of trace metals in the water column. This segment of the study, which gathered samples every two months for a year, was further divided into particulate and soluble heavy inelals. To gain some perspective into the retention of heavy metals in the hay, sediments collected twice throughout the bay were also analyzed for heavy-metal content. An organism collection was designed based on the criteria that the species contribute significantly to the biomass of the bay, be it a resident species or of commercial importance. Depending upon the criteria met, either whole animalsor edible portions were chosen for analyses. The metals chosen for analysis were: copper, chromium, cobalt, nickel, zinc, cadmium, iron, titanium, vanadium, mercury, arsenic, selenium, antimony, strontium, molyb- denum, beryllium, lead and also cyanide. All care was taken to avoid contamination in the collecting process, in sample preparation and in analysis. The only sample collection not totally successful was that of Fish. However, oysters, clams and some fish species were found in adequate numbers to give some idea of heavy-metal content in the living segment of Bay St. Louis. It had been hoped that the newly developed flameless techniques for atomic absorption could be used on all metals in the water samples. A great deal of time was devoted to adapting these techniques to the various matrices found in Bay St. Louis water. Though very sensitive and direct, flameless techniques at ihe present time are not suit- able to apply to numerous metals in great numbers of samples of varying composition. Lack of reproducibility, tremendous analysis time, and cost indicated that these highly praised techniques are best used on single sample, single metal problems. At present, the analyses are being concluded, and a final report is in preparation. Nutrients in St. Louis Bay (Funded by Du Pont): A sam- pling program was concluded in December 1978 to survey nutrients and other water-quality parameters in St. Louis Bay water to assess the distribution (laterally, vertically and temporally), source, and fate of these parameters. The choice of station locations was closely coordinated with other investigators at the Laboratory and associated projects 317 318 HOWSE to maximize data usability. The parameters chosen for study were: orthophosphate, total phosphorus, nitrate, nitrite, ammonia, chloride, sulfate, suspended solids, turbidity, alkalinity, and silica. Samples collected for inorganic and organic carbon were forwarded to the GCRL Environmental Chemistry Section for analyses. Most methods used in analysis, collection and sample handling were of EPA origin. Some methods required slight modifications to permit their application to coastal waters. At the present time, all analyses are complete and a compre- hensive data report is in preparation. Included will be: comparison of 1978 data with water-quality data from as early as 1966; comparison with the Pascagoula River and Back Bay of Biloxi; intercorrelation of parameters; distribu- tion as a function of salinity; proximity to proposed effluent sites; and season and trends within the phosphorus and nitrogen groups of nutrients. The Fate of Pollutants in Mississippi Sound (Funded by Mississippi-Alabama Sea Grant Program fM-ASGP]): This is a cooperative study with the Environmental Chemistry Section. Its objectives are as follows: to document the present load of pollutants in the rivers and estuaries of Mis- sissippi Sound; to g3in a historical perspective of pollution in that area by vertically profiling the pollutants in the sedi- ment column; to look at the distribution throughout the Sound as a function of sediment type and mobility; to assess the dangers of dredging in locales of high sediment pollution; to use key pollutants as indicators to trace pollutant move- ments; to educate the public to the current pollution situa- tion in Mississippi Sound; and to gain a means of predicting impact on Mississippi Sound under a wide range of environ- mental conditions. Since Pascagoula River is the most industrialized area along the coast, first efforts are being exerted there. This investigation is profiling the water quality in the Pascagoula River area. Included in the parameter list are: nitrate, nitrite, ammonia, orthophosphate, total phosphorus, suspended solids, turbidity, silica, phenols and Kjeldahl nitrogen. If phenol levels warrant, more sophisticated techniques will be developed to delect individual phenol components. Presently an attempt is being made to use phenolic aldehydes as tracers of paper mill waste movements. If successful, this will pro- vide a certain degree of prediction in examining pollutant movements in rivers. All data will be used ultimately in helping the State and local governments develop proper land utilization plans for the coastal zone. BOTANY SECTION, Dr. Lionel N, b'leuterius, Head Salt Marsh Vegetational Studies (Funded by GCRL): Quantitative information is being accumulated on the rela- tionship of marsh acreage versus open water in Davis Bay, a very productive estuarine system. In addition, the total area drained and amount of rainfall will be determined in this study of an entire estuarine ecosystem from the plant ecology viewpoint. A detailed vegetative map is being pre- pared as well as a map of the standing crop of all marshes surrounding Davis Bay. Vegetational structure of other Mis- sissippi salt marshes is being determined. This study will reveal the vegetational and ecological attributes of a very productive estuarine system and may have far-reaching consequences. Populational Studies on Salt Marsh Species (Funded by GCRL): This ongoing research is presently concentrated on the salt marsh rush Juncus toemerianus. Considerable popu- lation information has been gathered on the species and a portion of it is now in manuscript form. The ultimate goal is to document the distribution and the vegetative growth pattern of the major salt marsh species inhabiting the tidal marshes in Mississippi. Such populational studies are of considerable importance in relation to ecological work since ecotypes, single sexes, may dominate or compose large tracts of tidal marsh. Taxonomic work was also initiated as part of this study. Ecological Studies on Seagrasses and Salt Marsh Species (Funded by GCRL): This work involves synecological studies where more than one species compose the vegeta- tion. Included in this study is consideration of the hydraulic- aspects of flooding various salt marsh zones done in cooper- ation with the Physical Oceanography Section. Grand Bayou, a high salinity marsh dominated by Juncus rocmerianus on Deer Island, Mississippi, has been tentatively selected for this portion of the study. Tidal inundation and discharge rates can easily be established because of the small, contained ecosystem represented in Grand Bayou. A paper on tidal inundation and exposure has been prepared and accepted for publication. Quantitative data on plant productivity and the nutritive discharge of detritus and other water-quality parameters will be assessed on the discharge and on the rising tide. The nutrients of Grand Bayou salt marshes in relation to flood and ebb tides and the flux of soil-water salinity have been determined and manuscripts are in preparation. Studies of other ecological aspects of tidal marshes have been initiated. Biotic effects are also considered. Flowering phenology has been determined and a paper is in preparation. A graduate student completed thesis research on the response of the snail Littorina to the manipulation of salt marsh vegetation. Autecological Studies on Vascular Plants of Mississippi Salt Marshes (Funded by GCRL): This project is essentially an extension of populational studies, in that ecological parameters such as soil nutrients, soil-water salinity, eleva- tion, and other chemical and physical aspects of habitats (i.e., soil texture, evaporation), and the life history of the plant including germination are considered. Progeny and Genetic Studies on the Salt Marsh Rush, Juncus roemcrianus (Funded by GCRL): This work entails ongoing research begun several years ago. Plants have been grown from seed for several years to obtain Mendelian ratios, establishing the genetic mechanism responsible for the A Summary Report 319 sexual distribution found in this rush species. The work constitutes an effort to obtain basic information on this species which dominates Mississippi marshes. During the past year, controlled crosses between known parental types have been achieved and their seeds are presently being germ- inated. Hopefully, they will produce mature plants in less than the 2 years required under field conditions. An apparatus has been constructed in the greenhouse that can extend or shorten the photoperiod exposure to induce flowering. Also, experiments have been conducted dealing with the physiological requirement ol a cold period, known as vernalization, to induce flowering in this rush. If flowering can be induced, the growth and flowering cycle can be accelerated. An Illustrated Guide and Key to Salt Marsh Plants (Funded by M-ASGP and GCRL): The purpose of this work is to prepare an illustrated guide and key to the salt marsh plants of Mississippi. It entails about 1 80 line drawings and scientific descriptions of local species of vascular plants. Keys to families, genera and species are being prepared, A Phy to sociological Study of Horn and Petit Hois Islands (Funded by National Park Service, U.S. Department of Interior): This work was completed in 1978, data analysis and the final report completed in early 1979. Phytosocio- logical sampling was used to obtain information on com- munity composition and successional patterns and interrela- tionships between the plant communities on these islands. Significant products resulting from the work were large format maps, produced in seven colors, that delineated the major vegetational features of Petit Bois and Horn islands. They will be of considerable value in the proper manage- ment of the island sand invaluable as baseline data for future scientific studies. St. Louis Bay — Botanical Survey and Plant Ecology of Salt Marshesand Submerged Meadows (Funded by Du Pont). This work was completed in 1979 and the report is in the final stages of preparation. Vegetational mapping and com- munity composition of salt marshes and submerged grass beds were documented. Standing crop, annual production and chemical characterization of indicator plants and asso- ciated soils were determined as part of a baseline environ- mental study. Physiological Studies on Salt Marsh Plants (Funded by GCRL): Several experiments (cause and effect) were carried out in the greenhouse during fall, winter and spring. Modifi- cations arc needed to lower temperatures in the greenhouse before experiments can successfully be conducted during the summer. The effect of deficient nutrients, toxic levels of heavy metals, and the effects of different water levels have been determined. These data are presently being analyzed. Nutrient Enrichment Studies in Salt Marshes and Seagrass Beds (Funded by GCRL): This project involves several field experiments utilizing fertilizer. One study was com- pleted by a graduate student and a thesis prepared on the work. Another study entails nutrient loading of several different marsh types. The latter study has been in progress for several years and was previously a part of the general ecology studies described above. Two forms of nitrogen were applied to seagrass beds and the response observed. Further work is needed. Herbarium Collection of the Coastal, Estuarine and Marine Flora (Funded by GCRL): The herbarium of the Botany Section presently houses about 20,000 specimens of plants. Most of the collections have been made locally since 1970, and probably compose the most thorough col- lection of plants found in the northern Gulf of Mexico. Most of the herbarium specimens have been identified but only a few have been mounted on herbarium sheets. The herbarium is presently being organized and specimens cata- loged systematically. Duplicate specimens are exchanged with other herbaria throughout the United States, Lngland, Europe, Australia and South America for collections of their coastal, marine and estuarine plant specimens. The herbarium serves as a teaching and research collection and currently includes spermatophytes, algae and fungi, Addi- tional space is needed for an expansion of the herbarium. Tropic versus CONUS Military Materials and Equipment Evaluation Test (Funded by U.S. Army): A new experi- mental study was initiated in the spring of 1979 to deter- mine the effect of environmental factors on various military materials and equipment. This work is part of a nationwide military program. Studies on Plant Colonization on Dredge Spoil (Funded by GCRL): A considerable amount of information was com- piled over several years on plant colonization on dredged material. In addition, some information on plant succession has also been gathered. A more intense effort has recently been initiated because many years of observation have allowed insights otherwise unobtainable. Productivity and Decomposition Studies on Salt Marsh Plants (Funded by GCRL): Several studies were completed on this aspect of salt marsh research. In addition to esti- mates of standing crop, two regeneration studies were con- cluded. Manuscripts have not been prepared on these proj- ects, but the data have been analyzed. Assessment of decomposition was determined using nylon bags and new methods developed within the Botany Section. Further work is needed. ECOLOGY SECTION, Dr. Robert A. Wood man see, Head Phytoplankton Productivity in St. Louis Bay (Funded by Du Pont and GCRL): Phytoplankton productivity is a fundamental community process of primary significance to the aquatic food chain. It is affected by a number of naturally occurring variables and is sensitive to a variety of unnatural environmental perturbations. The photosynthetic rale of phytoplankton is being measured at six locations in St. Louis Bay by both the dissolved oxygen and radioactive carbon techniques, and is being related to light intensity, 320 HOWSE temperature, nutrients, chlorophyll, community composi- tion and grazing pressure. Environmental Baseline Survey of St. Louis Bay : Benthic Study (Funded by Du Pont and GCRL): Thirteen months of benthic infauna and epifauna collections were completed in December 1978 as part of the Laboratory’s baseline environmental survey of St r Louis Bay. Benthic animals from these collections were identified and the data subjected to statistical analyses. The analyses, which included multi- linear regression and cluster analysis, were done by the Laboratory’s Computer Section, the data processing center at Texas A&M University, and the Ecology Section’s mini- computer. Monthly sampling for benthic infauna has been continued at ihe same locations during the first half of 1979. Speci- mens from these collections have been partially processed and stored at the Laboratory. Results of this continued study will be used in conjunction with the first year’s work to investigate seasonal cycles and year-to-year changes in the benthic infauna of St. Louis Bay. Seasonal and Spatial Changes in the Macrobenthos of Simmons Bayou , Mississippi (Funded by GCRL): Analysis of the results of the 1976—77 benthic study of Simmons Bayou was completed. This study showed the adverse effects of a dead-end canal on both benthic infauna and water quality. A paper reporting these findings, entitled “Macro- benthos of Simmons Bayou and an Adjoining Residential Canal,” by James T. McBee and Walter T. Brehm has been accepted for publication in Gulf Research Reports. A Study of the Zooplankton and Flooring Components of the Water Column from the Surface to 1,200 Meters at OTEC Sites in the Northern Gulf of Mexico and Eastern Caribbean Sea (Funded by Department of Energy, Ocean Thermal Energy Conversion [OTEC] Program, Lawrence Berkeley Laboratory): A project to collect zooplankton and hydrographic data at possible OTEC sites in the Gulf of Mexico was initiated in June 1978. The current study is a continuation of the original contract which involved the collection and analyzation of zooplankton from an OTEC site south of Mobile, Alabama. It was expanded to include limited assistance with similar work at the Punta Tuna, Puerto Rico, OTEC site. Data are reported to the Lawrence Berkeley Laboratory, University of California. These data should provide the OTEC Program with some of the neces- sary biological data for proper design and environmental assessment of an offshore thermal energy conversion plant. EN VJR ON M ENT A L CHEMIS TR Y SECTION, Dr. Julia S. Lytle. Head Development of High Resolution Glass Capillary Gas Chromatographic Analysis Coupled with Data System (Funded by GCRL): Environmental pollution studies require constant updating and modification of accepted procedures to adequately deal with the complexity of separations and identifications of environmental pollutants. Recent improve- ments in gas chromatography demonstrated a need to make certain modifications to section procedures. Sample intro- duction into open tubular columns requires many special considerations that are not necessary for the larger packed columns. If the sample was to be introduced by the conven- tional microsyringe, the open, tubular glass capillary columns would be overloaded. To update section chromato- graphic capabilities, the Perkin-Elmer 3920 gas chromato- graph was converted to accept glass capillary columns using a split injection method. This system has been interfaced with a Perkin-Elmer Sigma 10 data system using special programmed calculation procedures. The Sigma 10 is also equipped with basic, a powerful programming tool for calculations such as merging of data from several chromato- graphic runs, statistical analyses and automatic parameter updating for methods developed in the laboratory. This combination has proven to be the essential component necessary to investigate a wide variety of environmental pollutants with a high degree of credibility. In performing analyses of environmentally significant molecules present in trace levels, the analyst is constantly seeking to extend the range of analyses to lower and lower concentration levels with accurate mreasurement. Intensified research efforts by national and slate governments have lead to intercalibration studies to assess the accuracy and precision of the data obtained. Petroleum Uptake by Marsh Plants (Funded by GCRL): Field experiments were designed to study the uptake of petroleum by marsh plants and to establish phylogenetic ties through hydrocarbon synthesis. Spartina a! tern if ora, Juncus roemerianus and Scirpus robustus stands were chosen tor these studies. Three types of crude oil were placed around the root systems by routine innoculatiOns into the sediment with a 100-ml syringe. After periods of 2 months and 6 months, tips of the plants were cut from each experi- mental plant and analyzed for high molecular weight hydro- carbons. Three separate experiments were carried out during different growth seasons, differentiating between maturation stages of individual plants. In each experiment, Juncus roemerianus absorbed crude oils into its tissue and Spartina and Scirpus did not. Not only did Juncus absorb petroleum hydrocarbons, but it produced almost equal amounts of alkenes and alkanes. Alkenes were almost absent in the other marsh plants. Biosynthesis of alkanes is not entirely understood and is even less understood for alkenes. By looking at various maturity stages in Juncus, insight has been gained into this biosynthesis. Some of the uptake experiments are presently being repeated and expanded to include uptake of naphthalene, and oqtadecene, an aromatic and an alkene compound. It is possible that Juncus could serve not only as a contributor of food for estuarine nursery grounds but also act as a buffer and absorb hydro- carbons to lessen the effect of oil spills. The Fate of Organic Pollutants in Estuaries and Rivers Emptying into the Mississippi Sound (Funded by M-ASGP and Du Pont): This study is a cooperative effort with the A Summary Report 321 Analytical Chemistry Section. The organic pollutants have been isolated and characterized; the trace metals and nutri- ents will be examined by the Analytical Chemistry Section. The object of the study thus far has been to document the hydrocarbon and total organic carbon levels in Bay St. Louis, Biloxi River and Bay, and the Pascagoula River system. In view of ever-expanding development of the coastal zone, continuing pollution assessment Is proposed to deal with the following issues of environmental concern: 1. The present conditions Qf Mississippi Sound and adjacent bays and rivers need careful documentation to determine just where emphasis should be placed in future monitoring efforts. 2. The sources of pollutants should be located and dis- persal of pollutants documented. The mechanisms responsible for transport and deposition of pollutants in any area of the Sound must be known for various environmental conditions. Prediction of the fate of materials discharged into the Sound system may then be possible. 3. The public should be made aware of the present and future dangers of pollution to water resources of the state. Only an informed public will be willing to take action to prevent future detriment to the environment and insist upon clean-up procedures. 4. Guidelines for proper development of the coastal zone should be facilitated by a thorough knowledge of potential impacts of pollutants at any location in Mississippi Sound. This study has two distinctly related areas of research. Trace metals to include such elements as copper, cadmium, zinc, nickel, manganese, silver, cobalt, lead and iron will be examined in all sample types used in the study. Their known toxic nature, stability and numerous sources warrant atten- tion in any pollution study. Hopefully, the data gained here will also be useful in predicting the fate of radionuclides as well. Among the organic pollutants being studied are hydro- carbons which can result from petroleum pollution. Fatty acids and alcohols, not occurring extensively in petroleum, may be used as tracers of natural organics in the Sound, as well as providing additional information on the composition of organic constituents of sediments and water. Both water samples (surface and bottom) and surface sediments were collected routinely at each sample site. Since trace metals and organics both are generally associated with fine-grain materials when in a nondissolved state, suspended material was examined separately from dissolved com- ponents and grain size analysis of sediments conducted. This may provide correlations to clarify sources of deposited pollutants and to assess the importance of suspended materials in transporting pollutants. Other studies have indi- cated the importance of trace metal-organic associations in water and sediments; therefore, this relationship will be examined as closely as possible. Where more appropriate, laboratory conditions will replace natural ones in trying to elucidate the character of this relationship. Studies of Chemical Constituents of Primitive Plants (Funded by GCRL): Cheinotaxonomic and geochemical studies are continuing on primitive plants. In the past, studies have been completed on ferns, mosses, fungi and lichens. The present study includes lilies, rushes, sedges and grasses. There are two purposes of the study. One purpose is to investigate the distribution of biosynthetically related compounds, hydrocarbons and fatty acids, relate them to a series of ancient plants, and determine what chemical changes took place in the evolution of plants. The other purpose is to establish hydrocarbon and fatty acid distribu- tion patterns which can help in identifying natural source materials and their environments, and distinguishing them from pollutant sources. Sediment High Molecular Weight Hydrocarbons in Bay St. Louis (Funded by Du Pont): During the past decade there has been an increasing concern over the possible effects of petroleum hydrocarbons in the marine environment. Because of this concern, a great amount of research is in progress on the biogeochemistry of these compounds. National agencies are initiating hydrocarbon baselines to be made on areas of potential oil pollution that would be sub- ject to economical and environmental stress. With the build- ing of a large Du Pont plant, it was determined that hydro- carbon baseline information was essential. To document present levels of hydrocarbons (aliphatic and aromatic) in St. Louis Bay, 13 stations were chosen for sediment studies to assess the hydrocarbon levels from the rivers and from known sites of possible hydrocarbon inputs, as well as correlate with other sediment studies made on the same stations. Sediments were collected during the First month of the study and hydrocarbon analyses made. These same stations were sampled during September, nine months after the First collection, and again analyzed. In an effort to use hydrocarbon data to detect the presence of petroleum pollution, parameters have been derived from gas chromatographic data which can be used to indicate the presence of petroleum hydrocarbons. Thirteen of these parameters were measured in all sedi- ments analyzed. Thus changes in these parameters can be detected by measuring the same parameters at any later time and can, therefore, establish both qualitatively and quantitatively the addition of petroleum influx to these sediments. FISHERIES MAN A CEMENT SECTION , Mr. William J. Demo ran. Head Oyster Resource Assessment and Monitoring Segment of the St. Louis Bay Baseline Survey (Funded by Du Pont): This study involved the mapping of existing oyster reefs to determine their present condition as to productivity, natural mortality, spawning and setting, and predators with emphasis on the incidence of one known disease that affects oysters along the Gulf coast. Historical and recent salinity data were 322 HOWSE analyzed to determine what effect they had on oyster growth in the Bay. The final report for this project is in preparation, A Survey and Assessment of Reef Shell Resources in the Mississippi Sound (Funded by the Mississippi Mineral Resources Institute): This project involved locating and mapping deposits of ancient oyster shells buried under the floor of Mississippi Sound. The quantity of shell material was estimated and the value of this resource determined at current market prices. Oyster Resources Damage (Funded by GCRL): Section personnel documented the damage to oyster resources caused by spring Hooding from Pearl River and opening of the Bonnet Carr6 Spillway. The study provided the basis for the Bureau of Marine Resources 1 application for unmatched federal funds to rehabilitate the damaged oyster reefs. The Bureau received $600,000 in federal funds under Public Law 88-309, Section 4— B. Section personnel planned and supervised the oyster rehabilitation project. In addition, proper documentation of the resource damages made it possible for oystermen and oyster dealers to apply for and receive loans from the Small Business Administration at an interest rate of 7-3/8%. FISHERIES RESEARCH AND DEVELOPMENT SECTION , Dr. Thomas D. Mcllwain, Head ANADROMOUS FISHES: Rearing and Stocking Striped Bass - Mississippi Gulf Coast (Funded by National Marine Fisheries Service [NMFS] , U.S. Fish and Wildlife Service and GCRL): The third seg- ment of the project dealing with the rearing and stocking of striped bass was begun in September 1978. The objectives of this program were to establish, by rearing and stocking, a striped bass population in Biloxi Bay; to stock sea-run striped bass and determine their success; and to establish a source of fry from Mississippi brood fish. Approximately 393,800 striped bass of South Carolina origin were stocked into Biloxi Bay. Some 56,700 of these fish were reared from eggs taken from Mississippi brood fish. The U.S. Fish and Wildlife Service provided 200,000 two- inch fingerlings from their hatchery at Meridian, Mississippi, and the remaining 193,800 were reared at GCRL from fry received from South Carolina. All spawning of Mississippi brood fish was done at the Mississippi Game and Fish hatchery facility on the Ross Barnett Reservoir. Brood fish were collected from the Pearl River near Jackson, Mississippi, by Mississippi Game and Fish Commission personnel. About 28,150 sea-run striped bass fingerlings were reared from fry provided by the State of Virginia. These fingerlings were stocked into the Bay of St. Louis, A total of 258 striped bass stocked in previous years were returned to project personnel. Over 400 stripers, weighing from 3/4 to 5 pounds, were tagged with Floy T— Bar tags and released. Three tags have been returned. Returns indicate little movement, although with so little data, it would be dangerous to generalize. A sampling program is in progress to check for natural reproduction of previously stocked bass and for occurrence of juvenile striped bass, to monitor previously stocked striped bass and continue assessing the results of all bass- stocking programs previously carried out in this area. Sport Fishing Analysis of St. Louis Bay (Funded by Du Pont): Data collection for this project was completed in December 1978. The work entailed gathering data on total effort expended and total harvest of sport fish caught in St. Louis Bay. Data were gathered on species composition, seasonal and numerical abundance, as well as on size compo- sition, method of capture, and catch per unit of effort. Data analysis is complete and a final report is in preparation. A Proposed Mississippi Marine Finfish (Selected) Fishery Management Plan (Funded by M-ASGP): A management plan for selected Mississippi marine finfish was developed and adopted by the Mississippi Marine Conservation Com- mission (MMCC). This was a cooperative effort with the University of Southern Mississippi (USM). A working group comprised of personnel from GCRL, USM, MMCC and Sea Grant Advisory Service, held workshop sessions each month. The MMCC selected ten species for inclusion in the plan and appointed a 12-member advisory committee to provide input from recreation and commercial fishermen, processors and consumers. Description and Comparison of the Eggs , Larvae, and Young of the Yellow Bass, Morone mississippiensis , with Striped Bass, White Perch, and White Bass (Funded by GCRL): Adult yellow bass have been collected in coastal Mississippi streams. Through temperature and photoperiod manipulation an attempt is being made to spawn these fish. The resulting eggs and larvae are being described and com- pared to the eggs and larvae of striped bass, white perch, and white bass. Food Habits and Feeding Selectivity of Larval Striped Bass under Intensive Culture Conditions (Funded by GCRL): Several types of live foods, as well as several types of pre- pared dry diets, are being tested as food for larval striped bass being reared under intensive culture conditions. To date, the most effective food has been weed zooplankton. No prepared diets have proved satisfactory. This is the second year of a three-year project. COMMERCIAL AND RECREA TIONAL FISHES: Fishery Monitoring and Assessment (Funded by NMFS and GCRL): The annual report for segment two of this project (October 1977— September 1979) was submitted on schedule. All scheduled monthly samples were collected and processed. Verified data were stored in the Laboratory computer. Selected analytical programs were used to write and publish reports on the relative abundance, size, growth, A Summary Report 323 and distribution of harvestable species each month. Cooperative efforts continue to expand the fishery data base for use in achieving optimum production from Mis- sissippi fishery resources through effective management planning and implementation. Information provided to the Mississippi Marine Conservation Commission (MMCC), Mis- sissippi Marine Resources Council (MMRC), National Marine Fisheries Service, Gulf States Marine Fisheries Commission, Gulf of Mexico Fisheries Management Council (GMFMC), fishermen, fishery industries, and various other State and Federal agencies contributed to a progressively improved scientific basis for Mississippi marine fishery management. Special shrimp sampling provided the MMCC with a sci- entific basis for seasonal and areal opening and closing of shrimp fishing seasons. The shrimp fishing community pro- vided cooperative sampling effort with commercial fishing gear and boats. Several newareasin State waters were added to the established sampling program. Experimental and commercial sampling showed almost identical results. The Commission opened the season June 15, after examining predicted dates and considering economic and social factors. Continued monitoring was carried out after the season opened. Results indicated that predictions from the sampling program were accurate. With the possible exception of croakers, all resources monitored in this project appear to be in good condition. Spotted seatrout and redfish provided good recreational catches and record volume of commercial redfish landings. A record catch of gulf menhaden was landed in 1978. Moni- toring of juveniles indicated a good crop for 1979. Through June, the 1979 season Mississippi landings showed a 29% increase over 1978. There was little change in fishing effort. Specimens collected in this project were provided to students and other agencies on request. The by-catch of the special shrimp sampling program was studied and, along with monitoring samples collected since the fishing season opened , will be researched for a master’s thesis. Fisheries Planning (Funded by GCRL, NMFS, MMCC and GMFMC): Active participation in fishery management planning activities of all concerned agencies in the Gulf of Mexico and several professional societies provided for effec- tive input of Mississippi’s interest in all Gulf of Mexico fishery management planning activities. Project personnel served in numerous important positions including chairman- ship and membership m key committees. Environmental Baseline Survey of Bay St , Louis, Nektonic Macrofauna (Funded by Du Pont): This segment of the multidisciplinary study of St. Louis Bay provided for collec- tion and study of the nektonic fauna of the bay. Sampling was completed in December 1978 and all samples were collected on schedule. Laboratory processing was completed as originally scheduled. Verified data for all collections were stored in the GCRL computer. Data analyses were carried out during the remainder of the contract period. Environmental Baseline Survey of Bay St. Louis, Nektonic Macrofauna (Funded by GCRL): This project is a continua- tion of the study initiated with Du Pont funding. The regular sampling program was carried out through June 1979, and is expected to continue through September. This will pro- vide two full years of data and strengthen the baseline data base for management. 1CHTHYOPLANKTON : Cooperative Billfish Study (Funded by M-ASGP and GCRL in cooperation with NMFS): Billfishes are important in sport and commercial fisheries of the Gulf region but little is known about their life history, biology, stock size or potential yield. Their larvae could provide a useful tool for estimating biomass and yield of adults, but the larvae of blue marlin, white marlin, and sail fish are difficult to separate from each other. This project initiated a study to resolve problems involved with identification of larvae of these three species from the Gulf ol Mexico and adjacent areas in the Atlantic. Once the larvae of various billfish species can be identified, their abundance in the plankton can be deter- mined and related to size of adult spawning stocks. The Role of Mississippi Sound in Recruitment to Sport and Commercial Fish Stocks (Funded by M-ASGP and GCRL): Mississippi Sound, located within the “fertile fisheries crescent” in the northeastern Gulf of Mexico plays a poten- tially important role in recruitment to sport and commercial fish stocks. Understanding the interactions among fish spawning, early life history patterns, and the environment of Mississippi Sound can lead to predictive capabilities related to effects of alteration of circulation patterns and introduction of pollutants on recruitment success, and in turn provide useful information for management purposes. This three-year study focuses on the pelagic early life stages of fishes, the most critical period in the life history of a species. It is during that period when year-class strengths and subsequent recruitment to fishable stocks are most likely determined. Objectives are to evaluate the importance of Mississippi Sound as a spawning and/or larval fish nursery area, to examine mechanisms of transport of fish eggs and larvae into and within estuarine nursery areas, to examine distribution patterns of pelagic young of important species, and to assess potential relationships between circulation patterns and survival of pelagic young and in turn future recruitment success. Larval Fish Collection (Funded by GCRL): Work has begun to establish a good regional collection of identified larval fishes from the northern Gulf of Mexico. Increased recognition of the importance of knowledge of the early life history of fish has created a need to know and identify the early pelagic stages. The collection will be useful as a reference source to other researchers studying the early life of Fishes in the northern Gulf. It will also be a source of material for studies of larval fish systematics as well as a teaching tool for graduate students interested in early life history research. 324 Howse The major initial source of material will be collections presently available at GCRL, as well as those planned for the future. Additional sources are also being sought. Prelim- inary acquisitions include over 50 identified species or species groups. GEOLOGY SECTION, Dr. Ervin G. Otvos, Head Offshore Barrier Island Study (Funded by GCRL): This ongoing study is aimed at understanding the geologic his- tory, genetic conditions, and present state of the six major Mississippi-Alabama barrier islands and the minor ones in Pelican Bay, Alabama. Three coreholes were drilled across Mississippi Sound in 1978, along a transect between Bayou la Bat re area (Alabama) and western Dauphin Island. At the same time, two additional coreholes were drilled in the Sound near eastern Petit Bois Island. Dredge samples from bottom sediments of the western Mississippi Sound were obtained from several locations for analysis. The Mississippi National Guard provided periodic photographic coverage of certain island sections, allowing monitoring of changes over a short period of time. Monthly photographic reconnaissance flights over the Pelican Bay islands were also made during the spring-summer of 1 979. Parts of the accumulated findings are being organized and processed for later presentation at professional meetings and for publication. Santa Rosa Island and Sound (Funded by GCRL): Study of the island, its lagoon and adjacent bays continued with granulometric and niicropaleontological analyses of drill core material provided by the U S. Army Corps of Engineers, testing laboratories and GCRL drillings. Complete sediment sequences of 1 5 coreholes from Santa Rosa Sound were pro- vided by the Corps, while the Section drilled an additional 1 5 shallow coreholes on the island and adjacent mainland areas. Comparison between this island and the Alabama- Mississippi barrier islands has major significance in under- standing their formation and development conditions, as well as the Holocene evolution of the whole northeastern Gulf coastal zone. Origins of Lake Pomchartraln and Surrounding Holocene Areas (Funded by GCRL): The organization of available research material was concluded and some of the results presented at the fall 1978 meeting of the Gulf Coast Asso- ciation of Geological Societies, Two papers have also been published on the subject. Holocene Geology of Hancock County Marshland (Funded by GCRL): Earlier obtained research material was organized; it provided the basis for a paper, prepared in conjunction with the Botany Section, for publication in SID A Contributions to Botany . Pleistocene Stratigraphy of Hancock County (Funded by GCRL): Detailed study continued of field samples and earlier drill material. New core material from four drillholes on the National Space Technology Laboratories site was obtained from the U S. Army Corps of Engineers. Five additional coreholes were drilled by the Geology Section. The research is aimed mainly at establishing the influence of late Pleisto- cene marine transgressions in the Hancock County area. Pleistocene Development in Southeastern Louisiana (Funded by GCRL): Field and laboratory work continued. Research results from the fossil-rich Tunica Hills (Mississippi- Louisiana) creek terrace sequence have been prepared and accepted for publication in Quaternary Research. Beach Sand Analysis { Funded by GCRL): Granulometric analyses were performed on numerous samples and a report on the results was provided to the Physical Oceanography Section. Sound Sediment Granulometry (Funded by GCRL): Granulometric analyses, related to various oyster reef areas, were performed on samples for the Fisheries Management Section. Samples were also processed for the Oyster Biology Section. St. Louis Bay (Funded by Du Pont): Monthly sediment analyses of collected Bay samples were performed on this project. Numerous additional samples were analyzed from various marsh areas along the northern Bay shores for the Botany Section. A report on the project has been submitted. After completion of the Du Pont project, sample analyses continued on a monthly basis for GCRL. MICROBIOLOGY SECTION, Dr. David W. Cook, Head Viral Evaluation of Prohibited Oyster Growing Waters (Funded by M-ASGP): This joint project with the University of Southern Mississippi is designed to assess the relationship between numbers of pollution-indicator bacteria in the water and the level of viruses found in oysters. GCRL is responsible for water- and oyster-sample collections and bacteriological analysis. Data produced will be available to State and Federal regulatory agencies for use in assessing present-day water quality standards. Environmental Baseline Survey of St. Louis Bay : Micro- biological Investigations (Funded by Du Pont): Water sam- ples from 14 stations in the Bay and adjacent rivers are being collected at 2-week intervals and analyzed for coli- forms and fecal coliforms. These data will document the present-day levels of sewage pollution in the Bay. Each month, water samples collected at 22 stations are analyzed for microbial biomass using adenosine triphosphate (ATP) methodology. These data will be correlated with phyto- plankton counts and productivity measurements. Populations of selected groups of bacteria are being studied in sediments from seven locations around the Bay. Metabolic activity rates and total biomass are being determined. Environmental Baseline Survey of St. Louis Bay : Pesticide Analysis (Funded by Du Pont): In this project, continued from last year, water samples were collected bimonthly from eight stations, sediment samples bimonthly from 1 1 stations, and oyster samples quarterly from two stations within St. Louis Bay. All samples were extracted and are cur- rently being analyzed by gas chromatographic methods for A Summary Report 325 chlorinated hydrocarbon insecticides and polychlorinated biphenyls. Steam Unit to Aid in Oyster Shucking . Part II. Microbial and Organoleptic Tests of Oysters Exposed to Steam (Funded by MMRC); When oysters are exposed to moderate temperatures, the adducter muscle relaxes* making the oyster easier to open. Investigations were carried out in cooperation with an oyster processor to determine if the heating process affected the microbiological or organoleptic quality of the oyster. Evaluations of the treatment on drip loss and shelf life of shucked oysters were also made. A Study of the Genus Bacillus in Marine and Estuarine Sediments (Funded by GCRL): Monthly sampling of sedi- ments from St. Louis Bay has continued to yield large num- bers of Bacillus. Over 1,000 cultures have been collected and are being identified in order to better understand the distribution, taxonomy and ecology of the genus Bacillus in estuarine sediments. Toxicity Testing: Inter-laboratory Comparison with Marine Animals (Funded by EPA): In conjunction with three contract and two EPA laboratories, GCRL conducted static and flow-through bioassay evaluations for the toxins silver and endosulfan against sheepshead minnows ( Cyprin - odon variegatus), possum shrimp {Mysidopsis bahia), and the copepod Acartia tonsa. These tests were conducted so that the EPA might gain insight into the expected similarity (or dissimilarity) of data as a function of the performing laboratory. Data generated thus far indicate that the static 96-hour LC 50 of endosulfan to C. variegatus is 2.2 ppb and to M. bahia 1.0 ppb, The static 96-houT LC 5() of silver to M. bahia was 176 ppb. Under dynamic conditions, endo- sulfan reflected a 96-hour LC S0 of 0.84 ppb to C. variegatus. Effluent Toxicity Evaluation: First Chemical Corporation (Funded by First Chemical Corporation): GCRL has con- tracted with First Chemical to perform flow-through bio- assay tests using the discharge effluent from its Pascagoula, Mississippi, plant. Test species are sheepshead minnows (Cyprinodon variegatus) and possum shrimp ( Mysidopsis almyra). These tests will be conducted quarterly for one year. First-quarter results indicate that for sheepshead min- nows, effluent concentrations less than or equal to 90% produced no mortality. For the mysids, mortalities at effluent concentrations less than 75% were not different from the controls. The biochemical oxygen demand, total inorganic and organic carbon, phenols, suspended solids, and total chromium analyses are being determined by the Microbiology, Environmental Chemistry, and Analytical Chemistry sections of GCRL as part of this contract. MICROSCOPY SECTION. Dr. William E. Hawkins, Head Studies on Intracellular Parasites and Tissue Responses in Oysters (Funded by M-ASC.P and GCRL): These studies continued for the second year. Oysters are being provided by the GCRL staff and the Food and Drug Administration Shellfish Sanitation Laboratory at Dauphin Island, Alabama, The oysters are being surveyed with light and electron microscopy for intracellular parasites. These parasites are found in inclusion bodies in the digestive gland. In addition, the incidences of inflammatory and hyperplastic lesions are being compared in oysters taken from various locations. The oyster may prove to be a useful indicator organism if a relationship is found between these cellular changes and certain environmental factors. Histological and Cytological Investigations of Various Organs and Tissues of the Atlantic Croaker (Funded by GCRL): This study is in its second phase which consists of preparation of an atlas of normal croaker histology and cytology. Croaker organs and tissues have been processed, sectioned, and photographed. The results of this study will provide a basis for determining pathological changes that might result from exposure to various toxicants. Studies on Histo pa Biological Effects of Heavy Metals on Marine Fish (Funded by GCRL): Studies are continuing on the effects of cadmium on tissues of the spot Lelostomus xanthurus. Initial efforts were aimed at determining the normal ultrastructure of the kidney and gills of these fish. In these studies, both transmission and scanning electron microscopy have been utilized. It was determined that after a 48-hour exposure of spot tissue to cadmium, the metal accumulated mainly in abdominal viscera and caused severe damage to proximal tubule cells in the kidney, OYSTER BIOLOGY SECTION, Dr. Edwin W. Cake. Jr.. Head Oyster Depuration in Mississippi: Engineering Assessments (Funded by M-ASGP and GCRL): The second phase of a 3-year study was completed. The study involved a sanitary engineering analysis of a small, pilot-scale, oyster depuration facility operated by the Oyster Biology Section at Point Cadet in Biloxi, Mississippi. Results indicated that water degradation in both open and closed depuration systems was not significant with regard to acceptable levels for waste discharged into receiving waters. In addition, the following conclusions were reached: solids generated during depura- tion can be removed via conventional gravimetric means; ozoniation provided adequate disinfection and reduced degradation of the process water; ozoniation will reduce or eliminate the need for wastewater treatment prior to dis- charge; and closed depuration systems can be operated for extended periods without significant problems and will function adequately in an open mode of operation. Enhancement of Oyster Production in a Tidal Lagoon in a U.S. Park Service Wilderness Area , Horn Island , MS. (Funded by GCRL): Study participants are attempting to increase the production of oysters in a wilderness lagoon via natural methods including branch culture, shell relaying, and the introduction of brood stocks from nearby island lagoons. All aspects of the study are being conducted with natural materials and without mechanical or motorized equipment as per wilderness guidelines. This is the first year of a two-year study in cooperation with the Gulf Islands National Seashore. 326 HOWSE Population Dynamics of Selected Oyster Populations in Mississippi Sound and Adjacent Waters (Funded by Mississippi Bureau of Marine Resources [MBMR] and GCRL): A one-year monitoring program was begun on five of Mississippi’s commercial oyster reefs to determine rates of spatfall, growth, natural and unnatural mortality, and the prevalence of oyster pathogens and predators. The study should be the forerunner of an extensive moni- toring program for all reefs to produce data needed for proper management of the State’s oyster resources. Development of an Oyster Management Model Applicable to the Mississippi Oyster Fishery (Funded by MBMR and GCRL): During this one-year study the Oyster Biology and Fisheries Management section staffs will acquire and evaluate existing oyster production models for applica- bility to the Mississippi Sound oyster industry. They will attempt to determine the technical information inputs required to operate such a model and suggest modifica- tions so that the selected model will apply to the State’s situation. Data from the monitoring study (see previous project) may be utilized to manipulate the chosen model. Oyster Depuration in Mississippi: An Evaluation of Off- bottom Relaying for Cleansing Oysters (Funded by GCRL): The first year was completed of a two-year study to compare “oftbottom, containerized” relaying with depuration and traditional “onbottom” relaying. Initial results indicated that polluted oysters held in plastic chicken coops cleansed sufficiently within the widely accepted 15-day “relaying” period. The second year of the study will concentrate on system analysis and modification to design the best contain- erized alternative to onshore depuration and onbottom relaying. Oyster Mariculture in Mississippi: Seed Oyster Hatchery Operation and Testing (Funded by GCRL): Current experi- mental oyster mariculture research at the Oyster Biology Research Facility of GCRL at Pi. Cadet, Biloxi, MS, includes, but is not limited to the following projects: seed oyster production (hatchery production); experimental raceway and tank culture of hatchery-reared seed oysters; evaluation of new cultch materials for hatchery-rcared seed oysters; operational monitoring and utilization of a low-cost and low-energy greenhouse for oyster culture; design and testing of windmills for pumping and circulating water in maricul- ture systems; optimization of natural setting versus wild setting; and the feasibility of utilizing natural spatfall to increase seed production using Maheo and shell spat collectors. Oyster Mariculture in Mississippi: Field Tests with Hatchery -Reared Seed Oysters (Funded by GCRL): These ongoing studies involve the utilization of seed from the GCRL hatchery in various student and staff research including: growth and survival of seed oysters in Mississippi Sound and adjacent waters, and nursery and field techniques for handling spat and seed oysters in the wild. PARASITOLOGY SECTION, Dr, Robin M. Overstreet, Head Commercial Fishes of Mississippi: Spawning and Miscel- laneous Biological Parameters (Funded by NMFS and GCRL): The first of two tasks in this project was to deter- mine the season of spawning, size of spawning fish, fecundity, and other aspects of reproduction for the spotted seatrout and red drum in Mississippi. The second task involved evaluating specific aspects of migration, feeding, growth, and health of a variety of commercial finfishes and shellfishes. Digenea from Marine Fishes of the Northern Red Sea (Funded by the Israel Academy of Sciences and Humanities): This long-term project will ultimately produce a monograph on piscine adult digeneans of Red Sea fishes for the Fauna Palaestina series. Many specimens already have been collected and more are expected within Ihe next three years. Simul- taneous work also is being conducted on other parasites of Israeli fishes, some of which have been implicated in diseases of humans that consume the fish and of fish that are reared commercially. Pathological Effects of Larval Thynnascaris Nematodes in the Rhesus Monkey (Macaca mulatto) (Funded by the U.S. Air Force): The primary purpose of the study is to determine the pathological alterations in the alimentary tract of monkeys that have been administered one of the common local larval nematodes. Studies of Parasites of the Northern Gulf of Mexico Region (Funded by GCRL): Several studies are underway dealing with various different parasitic organisms. These studies deal with the taxonomy, systematics, anatomy, life histories, pathological effects, and control of the organisms. Some of these parasites have been implicated in harm to commercial and recreational fishes. These organisms include microbes, protozoans, metazoans, and even the hosts and potential hosts for the organisms. Experimental Organism Culture Group (Funded by GCRL); In early 1979, the culture-holding group of the Parasitology Section moved part of its operation into the front section of the new Toxicology Building on the Labor- atory’s main campus. The purpose of this group is to develop techniques for culturing various freshwater and marine organisms and to supply these organisms to various sections and other State institutions for use in experiments, primarily toxicity testing and parasitological life-cycle studies. Presently, several species of fishes, algae, copepods, amphipods, and other species are being reared. The facilities include those necessary for algal culturing, spawning fish, and holding fishes and invertebrates. Toxicity Testing: Inter-Laboratory Comparison with Marine Animals (Funded by EPA): This study was con- ducted in cooperation with the Microbiology Section (see page 324). Effluent Toxicity Evaluation (Funded by First Chemical Corporation): This study was conducted in cooperation with the Microbiology Section (see page 324). A Summary Report 327 Life Cycle Stages of Cyprinodon variegatus to Philadel- phia Academy of Sciences for Toxicity Testing (Funded by Philadelphia Academy of Sciences): Eggs, 2-day old larvae, 28-day old juveniles, and adults are being cultured for tests to be conducted by Scott Paper Company of Alabama. PHYSICAL OCEANOGRAPHY SECTION, Mr. Charles K. Eleuterius, Head Hydrographical— Meteorological Atlas of Mississippi Sound (Funded by M-ASGP): Mississippi Sound is one of the most productive estuaries in the world. Results of studies on the hydrography and meteorology of Mississippi Sound and adjacent areas appear in numerous documents. Planners, management authorities, educators, laymen and scientists are confronted with investing considerable time in a review of the literature to obtain fundamental information on the area. Information on the physical-chemical characteristics of Mississippi Sound does not exist at present. A single volume summarizing present knowledge would be a valuable reference. This research to develop such a reference source involves extensive statistical analysis of existing sets of hydrographic data to determine characteristic seasonal levels and spatial distributions of physical-chemical parameters. pH, tempera- ture, salinity, dissolved oxygen and density. Statistical measures of central tendency and variability of each param- eter at four depths will be shown in the form of isopleth charts. Some of the more informative results of remote sensing studies of Mississippi Sound conducted by the Earth Resources Laboratory, National Aeronautics and Space Administration, will be included; also, summarized infor- mation on hurricanes, wind, rainfall, air temperature, wave climate, rivers, and physiography of the basin. It is expected that the atlas will go to press by December 1979. Hydrology of St. Louis Bay (Funded by Du Pont): The water quality of an estuary is dependent upon the character of the waters received and the residence time of waters within the basin. The transport of dissolved or suspended materials, pollutants included, is almost wholly dependent upon the natural circulation of waters. Anomalous perturbations in levels of physical and chemical parameters are only detect- able if a baseline or norm has been established. The objective of the hydrological study of St. Louis Bay was the development of a baseline of hydrographic param- eters to serve as an estimate lor “normal” conditions. The hydrologic data-eollection effort, which was coordinated with the other disciplines participating in the environmental baseline study, obtained measurements of water tempera- ture, salinity, pH, dissolved oxygen, turbidity (depth of extinction of visible light), water color, and currents. In addition, fixed and automated sampling platforms continu- ously recorded wind speed and direction, water elevations, water temperature, pH, dissolved oxygen and salinity. Analyses of these data provided information on the vertical structure of the water column, influence of river flows, circulation patterns, and seasonal trends in the levels of the physical-chemical parameters. This study was the first major investigation of the hydrology of St. Louis Bay. When released, results of the study should prove valuable in the management of this complex estuarine subsystem. Numerical Model of St. Louis Bay Circulation (Funded by Du Pont): Essential to ascertaining the fate of dissolved or suspended materials in an estuary is an understanding of the natural circulation of the basin waters. A finite-difference numerical model based on the hydrodynamic equations of motion and continuity was applied to St. Louis Bay. The model, which alluws for the flooding and subsidence of waters from land areas, accommodates wind stress and includes a quadratic form of bed resistance. A 30-second time step was used to provide the necessary spatial resolution to properly represent the basin geometry and current regime. The model was tested initially using a simple sine wave as input, then later with the prescribed tidal conditions. Model graphic output consists of computer-generated hydro- graphs of water elevation and current vector diagrams. Initial test results agreed well with current measurements from the 13 hydrographic surveys conducted rn St. Louis Bay. Testing of the algorithms for wind stress and river flow will be done prior to final production runs. The model will be a valuable investigative tool for future investigations of St Louis Bay. Hydrology of Mississippi Sound North of Petit Bo is Pass (Funded by MMRC): To properly manage the Mississippi Sound estuary, it is important to know the spatial and temporal variability of certain physical-chemical parameters. Previously acquired hydrographic data were analyzed to determine mean levels of water temperature, salinity, pH, dissolved oxygen, nitrite-nitrogen, nitrate-nitrogen, ortho- phosphate and total phosphate. These seasonal mean levels were displayed in depth-composited isopleth charts. In addition, the statistical distribution of each parameter for each cruise was graphically displayed. The results of this study provided a hydrographic characterization of a pre- viously little studied area of Mississippi Sound. De velopment of a Plan for the Exploration o f Mississippi 's Marine Mineral Resources (Funded by Mississippi Mineral Resources Institute): The judicious exploration and assess- ment of mineral resources in Mississippi’s coastal lands, marine waters, and earth beneath the waters of the estuaries and adjacent continental shelf, require that a plan of study be prepared. This plan, developed in consultation with a geological oceanographer and a geophysicist, and with input from staff members of several Mississippi universities, is intended to eliminate duplication, establish research priorities and promote cooperation among research participants. Emphasis has been placed on combining sampling where technically and economically feasible. The plan also includes research to ascertain the environmental impact expected in the event a particular mineral resource is developed. The plan is expected to be completed by October 1979. 328 HOWSE Characterization of Tidal Bayous and Development of Statistical Evaluation/Monitoring Techniques (Funded by GCRL): This study involves analysis of four years of almost daily measurements. Baseline conditions on a number of physical-chemical parameters are being established that will assist in recognizing anomalous events when they occur. Monitoring techniques based on multidimensional graphics are being explored as a practical tool for management authorities. Characterization of the tidal bayou by both chemical and physical constituents will be accomplished as part of this study. Determination of Fundamental Factors Affecting the Hydrodynamics and Ecology of Mississippi Sound (Funded by GCRL): This study is actually an aggregate of investiga- tions that have provided much specific information on Mississippi Sound. The results have been fundamental to furthering an understanding of the hydrodynamics and ecology of the estuarine basin. Information such as the volume of water, area of the air-sea interface, statistical distribution of depths, classifi- cation of Mississippi Sound as to estuary type, geographical definition of Mississippi Sound, and fundamental period of oscillation, have been determined under this broad study. Recently, cross-sectional areas of the passes into Mississippi Sound were determined by a bathymetric survey. Presently, emphasis is on determining the frequency and cause of low- oxygen waters in Mississippi Sound. In addition, vertical gradients in temperature and salinity are being investigated. The results of all the investigations grouped under this one research caption are providing fundamental information required to address hydrodynamically related problems. Until these fundamental factors are provided, complicated hydrodynamic questions cannot be answered. PHYSIOLOGY SECTION, Dr. A, Venkataramiah, Head Seasonal Variations in Glycogen, Total Fat, and Caloric Energies of the American Oyster in the Mississippi Sound (Funded by GCRL): Oyster quality was determined in the past on the basis of glycogen content. The present studies were undertaken to relate oyster ( Crassostrea virginica Gmelin) quality to seasonal changes in lipids which contri- bute more to the caloric content. The total lipid and glycogen contents were found to undergo a significant seasonal change in relation to size and sex. Glycogen content was low in July and October, and high in February. Fat content was low in October and high in April. The caloric content of oyster meat decreased in the following order: April, February, July and October. Among the lipid classes, free sterol fraction has yielded the highest calorific energy in both “lean” (October) and “fat” (February) oysters. Phospho- lipids from lean oysters yielded more calories than from fat oysters. Variations in caloric content seem related to the degree of unsaturation of lipid class. Seasonal and Emperical Predictions of Meat Growth in Reef Oysters from the Mississippi Sound (Funded by GCRL): The relationship between shell length and meat weight is used to set minimum-size limits for the harvest of some bivalves. Considerable attention has been paid to this problem in other species of bivalves but not in oysters from Mississippi Sound. Therefore, experiments were made to propose predictive models to describe the relationship between meat weight versus shell length on a seasonal basis. Males and females exhibited a polynomial increase in meat weight as shell length increased. Growth rates of the reef population, as computed from the models, suggest that oyster meats increase in weight from October to April and decrease from April to October. Males seem to lose their weight for a longer duration than females. Meat weight per umt length revealed variations in the oysters. Small males (30 mm) were heavier from July to October, while females of the same size were heavier from October to April. Effects of Starvation and of Algal Feeding on the Tissue Cholesterol Levels in Penaeid Shrimp (Funded by GCRL): Tissue lipid and cholesterol contents of brown shrimp Penaeus aztecus Ives were compared in the laboratory among starved individuals and those fed green algae Ulva lactuta and Enteromorpha sp. or a pelleted diet. Cholesterol levels seem to vary with size of the shrimp, sex and diet. Shrimp fed a pelleted diet showed an increase in cholesterol content with increased body weight. Females showed a higher choles- terol content in certain tissues than males fed on the same diet. Muscle cholesterol increased linearly with body weight in females, while it was not size-related in males. Starvation did not alter the cholesterol level except in hepatopancreatic tissue. The cholesterol level decreased significantly in shrimp fed on green algae. Extrapolating these results, it was sug- gested that the bulk of marketable shrimp (60-68 count per pound) have relatively lower levels of cholesterol than was reported in nutritional and medical literature. “Jumbo” shrimp (30 or less count per pound) showed a value close to the reported value. Compared to caviar, organ meats, and eggs, shrimp muscle showed a low cholesterol content. Toxicity and Impingement-Entrainment Studies (Phase I) for Ocean Thermal Energy Conversion (OTEC) Plants (Funded by Department of Energy [DOE] ): In proposed OTEC plants, solar thermal energy of the tropical oceanic surface waters can be converted into electric energy. The energy conversion is accomplished by evaporating ammonia in heat exchangers with the help of thermal energy from the surface water. The vapor drives a turbine attached to an electric generator and the exhaust gas from the turbine is condensed to liquid ammonia with cold water drawn from depths of 2,000 feet or more which is then pumped back to the evaporator. The problem areas in this technology are: (a) corrosion of heat-exchanger metals; (b) leakage of ammonia into sea- water from heat exchangers; and (c) continuous dosing of chlorine into the system to clean the heat exchangers of biolouling and chlorine discharge into seawater. These A Summary Report 329 components used in OTEC plants have been known to be toxic to marine plants and animals. The DOE contracted with the Laboratory to study the toxic effects of the three components as well as their syner- gistic effects on: (a) a commercially important marine fish, and (b) a biologically important species in the marine food cycle. On the basis of findings, recommendations will be made to the DOE concerning lethal levels, incipient lethal levels (beyond which 50% of the test animals will not survive for 96 hours), and sublethal levels of each component to the selected marine animals. Also the DOE will be advised con- cerning chlorine dosage levels in OTEC plants. Since Septem- ber 1, 1978, the folio wing conclusions have been made: A. Mullet (which spawn in offshore waters) and marine copepods (whichever are available in large numbers) or sar- gassum shrimp were collected as experimental animals. If time permits, both copepods and shrimp will be tested. B. An experiment was carried out to find out if starva- tion during bioassay would affect the behavior and survival of test animals. In mullets, no such effect was observed during the 96- and 144-hour bioassay periods. C. An experiment was carried out to determine the salinity tolerance range of mullet. Mullet (4 to 6 inches) could withstand a 1 to 40 parts per thousand (ppt) salinity range when transferred from a control of 20 ppt. This infor- mation permits testing mullet in a common test salinity to which they have been acclimated slowly from their habitat salinity. D. Collection and maintenance techniques of mullet in the laboratory have been established. After some initial problems, marine copepods and sargassum shrimp were held fairly well for about 2 months. E. Although bioassay techniques with aluminum and ammonia are fairly well established in other laboratories, chlorine chemistry in seawater is not well understood. It is only in recent years that this line of research has attracted the attention of power-plant operators. The experimental results published from other laboratories raised more questions than provided answers. Therefore, the following tests were made in the laboratory to understand chlorine behavior and standardize techniques for bioassay. 1. Chlorine demand was determined in uncondi- tioned, deionized water (unconditioned water is free from animal contact or their wastes) versus unconditioned sea- water. The seawater exhibited a chlorine demand, compared to no appreciable demand in deionized water. 2. Chlorine demand was compared between uncon- ditioned seawater and conditioned seawater. For conditioning the water, mullet, or any one of the experimental species, can be kept in it for varying periods of time and would secrete ammonia or other metabolic wastes. The conditioned water has shown more chlorine demand than unconditioned water. 3. Chlorine demand was determined in relation to 6, 12, 18 and 24 hours of conditioning in seawater. The chlorine demand increased directly in proportion to the increased conditioning periods with the highest in 24 hours and fhe lowest in 6 hours. 4. Chlorine demand was determined in relation to the volume of conditioned test media by holding ten fish in each of 5, 10, 15 and 20 gallons of media. It was found that the smaller the volume, the higher the chlorine demand, and vice versa. This is due to the presence in a smaller body of water of higher concentrations of ammonia with which chlorine possibly combines to form some kind of chloramine. 5. Chlorine demand was determined in relation to biomass by holding test animals having volumes of 122 and 152 grams in 20-gallon tanks. A greater amount of chlorine was lost, as expected, in tanks with 122 grams volume than with 152. The loss was attributed to the presence of a lower ammonia level, 0.53 ppm, in the tank with 122 grams of fish in comparison to 0.62 ppm in the second tank. Bioassay studies with ammonia are near completion and studies with chlorine are in progress. Based on the data, lethal, incipient lethal, and sublethal levels of ammonia for mullet and sargassum shrimp were identified. SYSTEMA TIC ZOOLOG Y SECTION, Mr. C. E. Dawson, Head Systematic Studies on Fishes of the Families Microdes- rnidae, Duclyloscopidae and Syngnathidae (Funded by the National Science Foundation): Systematic studies continued on fishes of the families Microdcsmidae, Dactyloscopidae and Syngnathidae. Review studies on the pipefish genus N/anrwcampus and the polytypic species Oostethus brachy- urus were completed. Descriptions of several new or little- known Atlantic and Indo-Pacific pipefishes weie completed. In addition, a manuscript treating 6 genera and 29 species of American pipefishes was all but completed during this period. In connection with these tasks and other current problems, studies were conducted on these types and other fishes in a number of museums in the United States, Europe, Australia, and New Zealand. SPECIAL FACILITIES MARINE EDUCATION CENTER, Mr. Gerald C. Corcoran, Curator Visits to the Center increased again this year, from 30,1 55 to 32,754. The increase was not as great as in previous years, which is an indication that the present facility is fast reaching the maximum number of visitors that can be accommodated. The Curator assisted with a workshop for minority teachers and exceptional high school students on the Gulf Park campus of the University of Southern Mississippi. His presentation centered around the adaptation of saltwater techniques to studies of freshwater animals. Most of tire 100 participants were from schools located far from the coast. The continuing education program designed for teachers had a total of 30 students enrolled during the year, 20 of whom were teachers. “Basic Techniques in Marine Science for Teachers” was the only course offered at the Center during this time. 330 HOWSE The student intern program was discontinued this year. In its place a volunteer summer program was initiated, gour students from the seventh through ninth grades assisted in the care and feeding of the exhibited animals and thus were informally introduced to local marine and freshwater species. A similar program is planned for FY 80. As in past years, the Creative Learning in Unusual Envir- onments (CLUE) groups from Memphis, TN, visited the Center, with a total of six groups participating. Arrangements were made for staff supervision of daytime and nighttime seining on the beach, a boat tour of Biloxi harbor, a visit to Marine Life of Gulfport and a visit to the Center. The White- haven Methodist Day School also took advantage of those arrangements for a visit. A radio program on sharks was presented on Station WGCM, Gulfport- In addition, the Curator appeared on Station WLOX— ' TV, Biloxi, on 1 1 different occasions and presented slide programs on local wildflowers, crabs, salt- water fish, freshwater fish and other marine subjects. A weekly program has been suggested. Personnel at the Center continue to act as consultants to Marine Life of Gulfport on problems of water quality and diseases of marine animals. The same service is offered to local pet shops and individuals. Information on how to start and maintain marine aquariums is provided upon request. Color slides of poisonous and nonpoisonous snakes of the area were provided for educational purposes to Howard Memorial Hospital of Biloxi and a hospital in New Orleans. The Center was requested to have copies of the slides made that might be retained by the hospitals and used in their continuing education program. Center personnel continue to be called on to identify local snakes for area hospitals providing treatment to snake-bite victims. Two new publications have been generated at the Center: “Banded Coral Shrimp”and a “Fun Book” for the elementary grades. The coral shrimp pamphlet notes that this animal was first reported from Mississippi waters since establish- ment of artificial reefs. The “Fun Book” is a coloring book featuring local animals. THE GUNTER LJBRAR Y t Mr. Malcolm S . Ware, Senior Librarian Statistics on the number of persons using the Gunter Library were kept during this year for the first time and the average was found to be 70 per working day. A total of 257 standing orders were maintained for journals and serials. Three new exchanges of publications were established, and 10 new subscriptions were opened. Back numbers for 35 journal runs were purchased, and 377 volumes were bound. Significant additions were made to the journal collection through affiliation with the Science Book & Serial Exchange (SBSE). Many individual and collected reprints were received through exchange and donation, and others were acquired through interlibrary Ioan/photocopy for the various research sections as follows: Anadromous, 12; Botany. 35; Ecology, 16; Environmental Chemistry, 11; Fisheries, 24; Geology, 45; Library, 12; Microbiology, 27; Oyster Biology, 17; Parasitology, 49; Physical Oceanography, 18; Physiology, 56; and Systematic Zoology, 13. Total photocopy transactions received numbered 335. There were 1 19 requests for interlibrary loans from other libraries. Book purchases numbered 304 this fiscal period and the average cost per volume was $28.50. Cataloging personnel processed 502 books and 336 reprints. Donations of books, journals, reports, and reprints were received from the following institutions and individuals: University of Southern Mississippi, Department of Geology; National Marine Fish- eries Service, Pascagoula Station; Ronald Lukens, Walter Brehm, John Steen, Sandra Sharp, Dr. Gordon Gunter, Dr. Ervin Otvos, Dr. Thomas Lytle, all of the Gulf Coast Research Laboratory; Dr. E. J. Harvey, Gautier, MS; Dr. B. H. Atwell, Earth Resources Laboratory, Slidell, LA; and Dr. P. Isaacson, New York Department of Public Service. ICHTHYOLOGY RESEARCH MUSEUM, Mr. C. E. Dawson, Head Three hundred sixty-eight lots, representing approxi- mately 1,200 specimens, were cataloged. This brings the total vertebrate holdings to 16,729 cataloged lots, about 150,315 specimens. Invertebrate holdings are 1,080 cata- loged lots, about 3,460 specimens. Important gifts of specimens, particularly Syngnathidae, were received from museums and research workers in Japan, the Philippine Islands, India, Australia and New Zealand. Loans were made to a number of U.S. and foreign institu- tions, and gifts or exchange materials were provided for collections in Mexico, Australia and Belgium. Identifications were provided for fishes sent by a number of U.S. and foreign investigators. The Gulf Coast Research Laboratory is a member insti- tution of the Association of Systematics Collections. WA TER ANAL YSIS LABORA TOR Y, Dr. Thomas F. Lytle, Head The Analytical Chemistry Section through the Water Analysis Lab is profiling the water quality in the Pascagoula River area. Included in the parameter list are: nitrate, nitrite, ammonia, orthophosphate, total phosphorus, suspended solids, turbidity, silica, phenols and Kjeldahl nitrogen. If phenol levels warrant, more sophisticated techniques will be developed to detect individual phenol components. Presently an attempt is being made to use phenolic alde- hydes as tracers of paper mill waste movements. If success- ful this will provide a certain degree of prediction in exam- ining pollutant movements in rivers. All data will be used ultimately in helping State and local governments develop proper land utilization plans for the coastal zone. A Summary Report 331 COMPUTER SECTION, Mr. David Boyes, Head The total number of jobs processed through the Computer Center was 3,079 with the hours run reaching 1312.53. This is a net increase of 35.8% for jobs processed and 21,0% in hours run over last year. The main sections contributing to the job total were: Du Pont Project (1,258 jobs), Oceanog- raphy (343 jobs), Finance (273 jobs). Fisheries (166 jobs), Graduate Program (155 jobs), Botany (123 jobs), and Parasi- tology (76 jobs); with the remaining jobs contributed by other sections. Pilot Study for Menhaden Catch I Effort Log (Funded by Gulf States Marine Fisheries Commission): The main objec- tives of this project were: collection of catch/effort logs for the 1978 season; the design of a card format for logs; design of codes for locations, vessels, plants and species; storage of data in a compatible format with NMFS menhaden data; and preliminary analysis of the data base. This project produced approximately 32,000 cards of data and ran 1 10 jobs during 1978-79. PUBLIC IN FORMA TION/PUBUCA TIONS SECTION, Miss Catherine Campbell , Head During the last half of 1978, section personnel performed primarily publications work. One large project consisted of typing masters for the printing of a colloquium on mackerels held earlier in the year by the Gulf States Marine Fisheries Commission (GSMFC). About 120 pages were set in an 814- by 11-inch format; this work resulted in the GSMFC publi- cation, Proceedings : Colloquium on the Spanish and King Mackerel Resources of the Gulf n f Mexico . The staff also handled the printing of the Laboratory technical journal, Gulf Research Reports. After Dr. Harold D. Howse, editor, accepted papers for inclusion in Volume 6, Number 2, of the journal, they were copy edited by the staff for style, consistent usage and other details, then masters were typed in page format for printing the book. Work was completed during November and December; finished copies were received from the printer in late February and approx- imately 760 copies were mailed by the PI/P staff. The first manuscript for Volume 6, Number 3, of Gulf Research Reports was received by the Section in early March 1979 and was copy edited and printing masters set. Beginning with this issue, the editor adopted deadlines for the submission of manuscripts as follows: August 1 for papers of 10 or more typewritten, double-spaced pages and September 1 for shorter papers. Early this year, the staff began preparations for printing a new descriptive brochure for the Laboratory. Photographs were made during the summer and fall of 1978 and the booklet was written and edited. During January and Feb- ruary 1979, printing masters were set in 7- x 10-inch format and page layouts were made. The brochure was printed during April. Twelve issuesof the Laboratory newsletter, Marine Briefs, were produced and the publication completed its seventh year and entered its eighth. Staff members wrote and edited copy, took photographs, typed masters for printing and laid out pages for one 8-page, nine 6-page and two 4-page editions. Approximately 3,800 copies were distributed monthly. During August 1978, the staff edited copy for Marine Education Leaflet No. 10, Polychaetes of Mississippi Sound, set masters and made the layout; it was printed in Sep- tember. The leaflet was written by Walter Brehm of the Ecology Section. In November, the printing of the summer bulletin describing the academic program was handled by the section, and various other miscellaneous printing needs of the Laboratory were handled as they arose. During July, August and September of 1978, the section continued to present a public information program entitled “What’s in the Gulf for You?” during visits to public libraries along the Mississippi coast. Earlier, in June, visits were made to Pascagoula and Moss Point libraries and, later, to the following libraries: Biloxi, Gautier, City-County (Bay St. Louis), Gulfport-Harrison, West Biloxi and Ocean Springs. A film, “World Beneath the Sea,” live exhibits and a staff member were provided by the Laboratory's Marine Educa- tion Center (MEC). Section personnel gave out free literature including Marine Education Leaflets, tide tables, shark recipes, marine careers information, and materials published by Sea Giant programs. Library personnel and patrons were made aware of the services and activities available through the MEC, the Laboratory, and Sea Grant. There was interest in continuing the program in the summer of 1979. however, due to the gasoline shortage, it was not offered. The section provided Laboratory participation in the Mississippi State University -sponsored Harrison County Fair at Edgewater Mall Shopping City in September 1978, and in the Scout Expo’ ’79 at Biloxi’s International Plaza and the exhibits of the annual meeting of the Mississippi Acad- emy of Sciences in Jackson, the latter two events in March 1979. During the spring of 1979, section personnel reworked a display panel located in theCaylor Building foyer, according to a new color scheme and design concept. This 4- x 8-foot exhibit depicts aspects of both the academic and research purposes of the Laboratory. The section continued to disseminate information of Laboratory activities to the general public. Thirty-five news releases were mailed to about 50 selected daily and weekly newspapers, television and radio stations, wire services and special correspondents. In addition, approx- imately 100 pictures were made of small groups of field trip and summer college students and these were sent, with cutlines, to hometown and campus publications throughout the country. Assistance was provided to a number of outside writers, photographers and television crews who sought to cover activities of the Laboratory. Conducted tours were given by the staff to a dozen high school, college, and professional groups. 332 HOWSE The section also obtained Laboratory staff members to serve as speakers for civic clubs and judges for science fairs. ACADEMIC PROGRAM NEW AFFILIATE Eastern Kentucky University in Richmond, Kentucky, affiliated with the Laboratory during the year. The total of out-of-state affiliates is now 39. SUMMER SESSION, Dr. David W. Cook, Registrar The 1978 summer academic session involved 91 students registering individually for a total of 120 student courses. Thirty-nine students registered through Mississippi schools, 56 through out-of-state affiliates and four through non- affiliated out-of-state institutions. Courses taught during the 1978 summer session were: Salt Marsh Ecology, Dr. Lionel N. Eleuterius, staff Marine Microbiology, Drs. David W. Cook and William W. Walker, staff Introduction to Marine Zoology, Dr. Buena S. Ballard, Southwestern Oklahoma State University Marine Vertebrate Zoology and Ichthyology, Dr. J. William Cliburn. University of Southern Mississippi Marine Invertebrate Zoology, Dr. Edwin W. Cake, Jr., staff Marine Fisheries Management, Mr. J. Y. Christmas, Jr., staff, and visiting specialists Marine Aquaculture, Dr. Edwin W. Cake, Jr., staff Marine Ecology, Drs. James T. McBee and Robert A. Woodmansee, staff Marine Botany, Dr. R. B. Channell, Vanderbilt University Parasites of Marine Animals, Dr. Robin Overstreet, staff Special Problems in Marine Science, staff During the 1978-79 academic year, 35 students earned credit in the course Basic Techniques in Marine Science for Teachers, offered at night at the Marine Education Center located in Biloxi. This course was taught by Mr. Gerald C. Corcoran, staff. GRADUA TE RESEARCH PROGRAM Courses offered in the Graduate Research Program during this period included: Seminar, Special Problems in Marine Science, Special Topics in Marine Science, and Graduate Research in Marine Science. A total of 72 semester hours credit were earned by these students. Four new students were accepted into the Laboratory's Graduate Research Program during the year. Three students completed their degrees and three students completed their research projects and returned to their parent campuses for further coursework. Fourteen students in the program were candidates for the master’s degree and nine candidates for the doctorate. Each candidate's name, thesis title, degree sought and home university are listed below according to the senior staff member directing their work: Dr. Edwin W. Cake, Jr . . David H. Barnes, “Polychaetes associated with an artificial reef in the north central Gulf of Mexico,” M.S., University of Southern Mississippi. David A. Blei, “A successional study of the hydrozoans inhabiting an artificial reef in the north central Gulf of Mexico,” M.S., University of Southern Mississippi. Alfred P. Chestnut, “Substrate competition between Crassosrrea virginica (Gmelin) and associated sessile marine invertebrates,” Ph.D., University of Southern Mississippi. William W. Falk, “Food habits and feeding selectivity of larval striped bass, Morone saxatilis (Walbaum). under intensive culture,” Ph.D., University of Southern Mississippi. Kenneth Hase, “Enhancement of oyster production in a tidal lagoon in a U.S. Park Service wilderness area,” M.S., University of Southern Mississippi. Katherine A. McGraw, “A comparison of the growth and survival rates of hatchery-reared and natural oyster spat at selected locations in the Mississippi Sound and adja- cent waters with comments on the biology of oysters in Mississippi,” Ph.D., University of Washington. John E, Supan, “A comparison of ‘off-bottom’ relaying of oysters in the Mississippi Sound,” M.S., Univer- sity of Southern Mississippi. Mr. J. Y. Christmas, Jr.: James R. Warren, “Changes in the population of the juvenile groundfish, Micropogonius undulatus, Leiostomus xanthurus and Cy noscion arenarius, from Mississippi Sound before and after the opening of the 1979 shrimp season,” M.S., University of Southern Mississippi. Dr. Lionel N. Eleuterius: James C. Garrison, “Some relationships of salt marsh vegetation to abundance of the marsh periwinkle Littorina irrorala Say,” M.S., University of Mississippi. Stephen H. Sky-Peck, “A study of growth and nitro- gen content ot'Spariina alterniflora and J uncus roemerianus in response to source and concentration of nitrogen,” M.S., University of Mississippi. Dr. Gordon Gunter : Zubir bin Din, “The food and feeding habits of the common bay anchovy, Anchoa mitchilli diaphara Hilde- brand,” M.S. degree awarded 1979, University of Mississippi. Dr. Thomas D. Mcllwain : Frederick E. Schultz, “Description and comparison of the eggs, larvae, and young of the yellow bass, Morone mississippiensis, with striped bass, Morone saxatilis, white perch, Morone arnericanus, and white bass, Morone chry- sops M.S., University of Mississippi. Dr. Robin Overstreet: Daniel R. Brooks, “Evolutionary history of digenetic trematodes infecting crocodilians, including revision of Acanthostominae Poche, 1926 (Digenea: Cryptogonimidae),” A Summary Report 333 Ph.D. degree awarded 1979, University of Mississippi. Thomas L. Deardorff, ‘‘Nematodes of the genus Thy- nascaris Dollfus 1933* (Anisakidea) in the northern Gulf of Mexico,” Ph.D., University of Southern Mississippi. Alan C. Fusco, “The life cycle and development of Sirocamallanus cricotus. with notes on the taxonomic status of the genus,” M.S. degree awarded 1978, University of Southern Mississippi. Tom E. Mattis, “Larval development of two trypan- orhynch tapeworms from Mississippi Sound,” Ph.D., Uni- versity of Southern Mississippi. Mobashir Ahmad Solangi, “Pathological changes in some estuarine fish exposed to crude oil and its water- soluble fractions,” Ph.D., University of Southern Mississippi. Dr. A. Venkataramiah: Ann L. Gannam, “Effect of replacing dietary animal protein with plant protein supplemented by methionine on the growth and survival of Penaeid shrimp,” M.S. , University of Southern Mississippi. Shiao Vu Wang, “Studies on the effect of declining oxygen tension on the respiratory rate of brown shrimp, Penaeus aztecus Ives in relation to temperature and size,” M.S., University of Southern Mississippi. Dr. Robert Woodmans.ee: Zoghlul Kabir, “Relationship between the diurnal vertical migration and egg development in planktonic cope- pods in Mississippi Sound and adjacent northern Gulf of Mexico waters,” Ph.D., University of Mississippi. John P. Steen, “Factors influencing the spatial and temporal distribution of selected crustacean plankton species in Davis Bayou,” Ph.D., University of Mississippi. Michael C. Torjusen, “The distribution, abundance and feeding habits of larval and juvenile bothid flatfishes of Mississippi Sound and adjacent waters,” M.S., University of Mississippi. SCIENTIFIC FIELD TRIP PROGRAM As an adjunct to the teaching program, each year the Laboratory provides living accommodations, classroom laboratories, and essential services to visiting scientific field trip groups made up of college and university students and their professors. Such groups may stay for periods of up to several weeks, live in the dormitory, use Laboratory boats to make collections of marine life from the sea and from the beaches of offshore islands, and study their speci- mens in the classroom laboratories. During the year the Laboratory was visited by 33 field trip groups. The total number of people involved were 470 professors and students who stayed an average length of 4.18 days. Some came as far as 2,000 miles to study the marine life of the Gulf of Mexico. SPECIAL AND COMMUNITY SERVICES FISHER Y ASSISTANCE The Biloxi Schooner (Funded by GCRL): A newsletter, designed especially for the processing segment of the sea- food industry, was published monthly. It entered its second volume. The current mailing list is composed of 75 seafood companies and industry-related persons in Mississippi and five other states. Its content is technical in nature relating directly to the business of seafood production. Source material comes from Laboratory research, trade journals, scientific papers, Federal agency publications, and informa- tion gathered at seminars,conferences,and trade conventions. Seafood Merchandising Circular-Oysters (Funded by GCRL): In the previous year an educational fact sheet had been written at the request of a seafood packers association, to help food distributors and retailers better understand the nature of oysters. It was the intent of this fact sheet that better handling and selling would result by making more people in the food distribution chain better acquainted with this highly perishable product. A supply of waterproof paper was located and 3,000 copies were printed and given to oyster packers to put in their boxes of iced oyster jars before shipment to stores throughout the country. Wastewater Sampling Program (Funded by GCRL): To prepare the seafood industry for strict requirements of water pollution regulations administered by the EPA. this program was set up to test seafood plant wastewater effluent. The objective is to measure the “conventional pollutants” as defined by the EPA. There are limits on the amounts of these pollutants that can be contained in plant effluent if it is discharged into local waters rather than into a sewerage system. If samples tested show that a plant’s wastewater contains more than the allowable amounts of pollutants, then a plan is drawn up to help the particular plant lower these levels. The stale pollution control agency operates a waste- water discharge permit system subject to EPA approval; weekly sampling and a monthly report are required. Test results from this sampling program are reported to plant owners, who in turn use these data in their reports to the state. Data are gathered on each product processed. From December through June, 38 complete sample sets were made, which required spending 155.5 hours during 62 visits to the plants. These data will be of added benefit to the seafood industry in relation to the proposed regional sewerage system being planned by the state and EPA. Eventually that system will require all seafood plants to discharge their effluents into a treatment plant, A sewer-use ordinance will be drawn up setting allowable levels of pollutants entering the treatment plant. Data being accumulated from this sampling program will be of future value in helping to obtain realistic ordinance limitations. Due to the complexity and potential impact of the EPA’s wastewater guidelines, a reference library was started to keep this office informed and serve as a source of information for the seafood industry. The collection now contains a set of the laws, their amendments, and up-to-date rule changes; 334 HOWSE a 15-volume collection of documents developed to facilitate compliance of the food industry with the regulations; and research papers and other reference materials that have been developed on the seafood industry. additional assistance Extensive freezing and packaging experiments for a number of seafood products were begun at the request of a processor. This is a continuing project carried on at the sea- food plant. The experiments involve product preparation, freezing time/temperature studies, packaging material evalu- ation, and quality determination. Assistance was requested by an industry member who wanted to locate a volume source for several species of fish that were in high demand but could not be supplied locally. A marketing study was done of catch and distribution data from the southeastern states. The study defined a middle- Atlantic coast state as a good source of supply which was also within a reasonably economical transportation range from the Gulf coast. The names of fish dealers in that area were obtained and contact was made. Three industry members requested assistance concerning a seafood product shipping regulation. A study of published research was done to examine the basis for the regulation and gather support data for any proposed changes. These data were compiled in a statement on the issues involved with the regulation. This matter is currently under consid- eration by the seafood industry at the national level. This work will carry over into next year. EN VIR ON ME NT A L A FFAIRS The Environmental Affairs Committee is composed of all senior scientific staff members and is coordinated by the Ecology Section. The committee provided an interdis- ciplinary approach to environmental problems in the wet- lands and estuaries of Mississippi, primarily as a service to the Mississippi Marine Resources Council, which partially funded this work. However, (he committee also cooperates with other State and Federal agencies on special projects that are not under the direct jurisdiction of the Council. The majority of this work deals with the review of permit requests for work proposed in the wetlands and estuaries. Committee members made comments and recommendations on permit requests. In most cases a site visit was made by representatives of the Committee. Based upon these inputs, a letter to the Council was drafted stating any objections the Committee might have, reasons for those objections, and recommendations that might reduce or eliminate the objections. The Committee reviewed 54 permit applications during the year. In addition, a statement on the proposed 201 Regional Water Pollution Abatement Plan was drafted and presented at a public hearing convened by the Mississippi Air and Water Pollution Control Commission. Five members of the Committee were also members of the Deer Island Study Committee which was formed to assess the impact of a proposed skylift transportation system and the potential impact of 600 visitors per hour on the flora and fauna of Deer Island and the surrounding waters. PUBLIC SEMINARS The Gulf Coast Research Laboratory hosts a series of staff seminars throughout the year. These seminars are open to the public and speakers include inviled scientists as well as officials from various levels of local, state and federal government. The central purpose of the seminars is to pro- mote belter dissemination, understanding, and use of scien- tific information at all levels of society. Seminars presented during fiscal year 1979 were as follows: “ Principles of Health Ph ysics in the Radiochemistry Lab- oratory " by Mr. Ronald J. Forsythe, Assistant Director, and Mr. Kenneth Waller, Health Physicist, Regulatory Agent, Radiological Health Division, Mississippi State Board of Health, July 11, 1978. ‘Planetarium Science " by Mr. Jim McMurtray, Director, STARS Planetarium, July 25, 1978. “ Evolution of Several Marine Invertebrate Groups as Interpreted from the Fossil Record " by Mr, Jim Garrison, Botany Section, Gulf Coast Research Laboratory. July 28, 1978. “ Transport and Fate of Organic Compounds in Rivers and other Gulf Coast Hydroscience Center Research " by Dr. Dave Shultz, U.S. Geological Survey, Research Hydrolo- gist, National Space Technology Laboratories, August 8, 1978. “Testing Hypotheses of Evolutionary Histories of Para- sitic Helminths " by Mr. Daniel R. Brooks, Parasitology Section, Gulf Coast Research Laboratory, August 15, 1978. “Mississippi Cooperative Extension Service. . . .Research and Services ' ' by Mr. Leonard Slade, Jackson County Exten- sion Agent, August 22, 1978. " Mechanics of Enhanced Recovery "by Mr. Dave Meltzer, Senior Reservoir Engineer, Secondary Recovery Offshore Platforms, Chevron U.S. A., Inc., September 12, 1978. “Trends in Medical Research " by Dr. James B. Martin, M.D., Ocean Springs. September 26, 1978. “Salient Vegetative Features of Tidal Marshes and Evolu- tionary Implications from Plant Autecology " by Dr. Lionel Eleuterius, Head, Botany Section, Gulf Coast Research Laboratory, October 10, 1978, “Future Plans of Mississippi Power in Developing Energy Reserves" by Dr. Harry H. Bell, Jr., Vice President Engineering and Operations, Mississippi Power Company, October 24, 1978. “Assembly Line, Modular Production of Ships at Ingalls Shipbuilding " by Mr. A. C. Weeks, Litton Industries, Ingalls Shipbuilding Division, November 7, 1978. “Hurricane Meteorology and Reconnaissance ” by Capt. Jim Perkins, Meteorologist, Keesler Air Force Base, Novem- ber 21, 1978. A Summary Report 335 “Ecology of the Birds of Horn and Ship Islands , Missis- sippi" by Mr. Wayne C. Weber, Department of Biological Sciences, Mississippi State University, November 28, 1978. “Food and Feeding Habits of the Common Bay Anchovy , Anchoa mitchilli’ f by Mr. Zubir bin Din, Physiology Section, Gulf Coast Research Laboratory, November 30, 1978. “ Tick-Borne Rickettsial Diseases in Mississippi " by Dr. Lane Foil, Department of Entomology, Mississippi State University, December 5, 1978. “ The Gill Netting-Sport Fishing Controversy in the Mississippi Sound ” by Dr. Wendell Lorio, Director, Missis- sippi State University Research Center, National Space Technology Laboratories, January 16, 1979. “Gulf Teleost Cell Structure ” by Dr. Joe Wharton, Department of Microbiology, University of Mississippi Medical Center. January 23, 1979. “Marine Advisory Program Activities and Coastal Devel- opment" by Dr. David Veal, Mississippi Sea Grant Advisory Service, February 20, 1979. “Methods of Handling and Shedding Blue Crabs " by Ms. Harriet Perry and Mr. Larry Nicholson, Fisheries Section, Gulf Coast Research Laboratory, March 6, 1979. “Effects of Changes in Salinity on Biochemistry and Surface Ultrastructure of the Gill of the Mullet, Mugil cephalus ” by Dr. Fred Hossler, Department of Anatomy, Louisiana State University Medical Center, March 20, 1979. “Fish Eggs and Larvae : A Resource Assessment Tool ” by Dr. Sally L. Richardson, Fisheries Section, Gulf Coast Research Laboratory, April 10, 1979. “Present Status of Larval Taxonomy of Myctophid Fishes " by Dr. Muneo Okiyama, Associate Professor, Divi- sion of Marine Ecology, Ocean Research Institute, University of Tokyo, April 11, 1979. “ Utilization of Seafood Products" by Mrs. Bertha Fon- taine, Seafood Consumer Specialist, National Marine Fish- eries Service, April 24, 1979, “Home Health Service in Jackson County” by Nica Cason, R.N. and Joyce Rivera, R.N., Public Health Nurses, Jackson County Health Department, May 8, 1979. “Geology of the Gulf Coast " by Dr. Ervin Otvos, Head, Geology Section, Gulf Coast Research Laboratory, May 22, 1979. “ Toxicology Capabilities at the Gulf Coast Research Laboratory " by Dr. William Walker, Microbiology Section, Gulf Coast Research Laboratory, June 5, 1979. “A Study of Growth and Nitrogen Content of Spartina alternijlora and Junt as roemerianus in Response to Source and Concentration of Nitrogen ’* by Mr. Stephen Sky-Peck, Botany Section, Gulf Coast Research Laboratory, June 21, 1979. “Basic Studies in Reproduction Using Nematodes as Experimental Models ” by Dr. Eugene Foor, Wayne State University, June 26, 1979. STAFF PUBLICATIONS Brehm, Walter T. 1978. First Gulf of Mexico coast record of Manayunkia speciosa (Polychaeta: Sabellidae). North- east Gulf Science 2(T):73— 75. Brooks, Daniel R. 1978. Evolutionary history of the cestode order Proteocephalidea. Systematic Zoology 23(3): 312-323. and Alan C. Fusco. 1978. Some digenetic trema- todes from caudate amphibians in the southeastern United States. Journal of the Mississippi Academy of Sciences 23:95—99. ____ and Tom E. Mattis, 1978. Redescription of Nagrnia floridensis Marked, 1953 with discussion of the compo- sition of the Anaporrhutinae Looss, 1901 (Digcnea; Gorgoderidae). Proceedings of the Helminthological Society of Washington 45(2): 1 69- 1 7 1 . and Monte A. Mayes. 1978. Acanthobothrium clectricolum sp. n. and A. lintoni Goldstein, Henson, and Schlicht 1969 (Cestoda: Tetraphyllidae) from Narcine brasiliensis (Olfers) (Chondrichthyes: Torpedini- dae) in Colombia. The Journal of Parasitology 64(4): 615-619. and Robin M. Overstreet. 1978. The family Liolopidae (Digenea) including a new genus and two species from crocodilians. International Journal for Parasitology 8(4): 267 -273. and James R. Palmieri. 1978. Philophthalmus pidchrus sp. n. (Digenea: Philophthalmidae) from the intestinal ceca of a Malaysian moorhen. Proceedings of the Helminthological Society of Washington 45(2): 166-168. and Gerald D. Schmidt. 1978. Aeanthotaenia overstreeti sp. n. (Cestoda: Proteocephalidae) from a Puerto Rican lizard, the first acanthotaeniine in the new world. Proceedings of the Helminthological Society of Washington 45(2): 193 — 195. Buckner, Richard L., Robin M. Overstreet, and Richard W. Heard. 1978. Intermediate hosts for Tegorhynchus furcatus and Dollfuseniis chandler! (Acanthocephala). Proceedings of the Helminthological Society of Wash- ington 45(2): 195-201. Cake, E. W., Jr. 1979. Polypocephalus sp. (Cestoda; Lecan- icephalidae): A description of tenaculo-plerocercoids from bay scallops in the northeastern Gulf of Mexico. Proceedings of the Helminthological Society of Wash- ington 46(2): 165-170. Dawson, C. E. 1978. Review of the Indo-Pacific pipefish genus Bhanotia „ With description of B. nuda n. sp. Pro- ceedings of the Biological Society of Washington 91(2): 392-407. . 1978. Description of a new Western Australian pipefish ( Chneroichthys latispinosus), with notes on Syngnathus tuckeri Scott and Nannocampichthys Hora and Mukerji. Records of the Western Australian Museum 6(4) :4 13-421. 336 Howse and G, R. Allen, 1978. Synopsis of the “finless” pipefish genera ( Penetropteryx , Apterygocampus and Enchelyocampus, gen. nov.), Records of the Western Australian Museum 6(4): 39 1-4 1 1 . . 1979. A new wormfish (Pisces: Microdesmidae) from the eastern tropical Atlantic. Capeia 1979(2): 203-205. , F. Yasuda and C. Imai. 1979. Elongate dermal appendages in species of Yozia (Syngnalhidae) with remarks on Trachyrhamphus. Japanese Journal of Ichthy- ology 25(4):244- 250. Deardorff, Thomas L. and Daniel R. Brooks. 1978. Passer- ilepis schmid ti sp. n. (Cestoidea: Hymenolepididae) from the blue jay, Cyanocitta cristata L. in Nebraska. Pro- ceedings of the Helminthological Society of Washington 45(2): 190—1 92. and Robin M. Overstreet. 1978. Thynnascaris rhacodes sp. n. (Nematoda: Ascaridoidea) in fishes from the Israeli Mediterranean coast. Annales de Parasitologie Humaine et Compares 53(5):5 19 525. , Gerald D. Schmidt and Robert E. Kuntz. 1978. Allohymenolepis palawanensis sp. n. (Cyclophyllidea: Hymenolepididae) from the Philippine bird, Nectarinia jugularis (Tweeddale 1878). The Journal of Helmin- thology 52(3):21 1— 213. Eleuterius, Charles K. 1978. Classification of Mississippi Sound as to estuary type by vertical salinity structure. Journal of the Mississippi Academy of Sciences 23:23-32. _____ . 1978. Geographical definition of Mississippi Sound. Gulf Research Reports 6(2): 179-1 81 . . 1978. Classification of Mississippi Sound as to estuary hydrological type. Gulf Research Reports 6(2): 185-187. Eleuterius, L. N. 1978. Book Review: Coastal Vegetation, 2nd Ed., by V. J. Chapman. Plant Science Bulletin (A publication of the American Botanical Society) 24N:32. . 1978. Arevised description of the salt marsh rush, J uncus roemerianus, SJDA Contributions to Botany 7(4): 355-360. and S. McDaniel. 1978. The salt marsh flora of Mississippi. Castanea 43(2):86— 95. and Charles K. Eleuterius. 1979. Tide levels and salt marsh zonation. Bulletin of Marine Science 29(3): 394_400. and Ervin G. Otvos, Jr. 1979. Floristicand geologic aspects of Indian middens in salt marshes of Hancock County, Mississippi. SJDA Contributions to Botany 8(1): 102—1 12. Foster, C. A., T. G. Sarphie and W. E. Hawkins. 1978. Fine structure of the peritrichous ectocommensal Zootham- niurn sp., with emphasis on its mode of attachment to penaeid shrimp. Journal of Fish Diseases 1:321—335. Fusco, Alan C. and Robin M. Overstreet. 1978. Ascarophis distortus , a new spiruroid nematode from a chaetodontid fish in the northern Red Sea. Proceedings of the Biolog- ical Society of Washington 9 1(2):374— 378. and Robin M. Overstreet. 1979. Two camallanid nematodes from Red Sea fishes including Procamallanus elatensis sp. nov. from signaids. Journal of Natural History 13(l):35-40. Gearing, Juanita N., Patrick J. Gearing, Thomas F. Lytle and Julia S. Lytle. 1978. Comparison of thin-layer and column chromatography for separation of sedimentary hydrocarbons. Analytical Chemistry 50( 1 3): 1 833-1 836. Gunter, Gordon. 1978. The river shrimp genus Macro - brachium and its aquaculture potential in Mississippi. Proceedings Annual Meeting, Mississippi Chapter Amer- ican fisheries Society 2:11—22. ______ and W. David Burke. 1978. Further notes on how oysters land when planted. Proceedings of the National Shell fisheries Association 68: 1 -4. Hawes, Suzanne R. and Harriet M. Perry. 1978. Effects of 1973 floodwaters on plankton populations in Louisiana and Mississippi. Gulf Research Reports 6(2): 109— 124. Hawkins, W. E. and H. D. Howse. 1978. The cardiac ganglion of the blue crab, Callinectes sapidus Rathbun. A light and electron microscopic study. Transactions of the American Microscopical Society 97(3):363-380. Higgins, George G. and Charles K. Eleuterius. 1978. Missis- sippi Sound: Volume, surface area and bathymetric statistics. Journal of the Mississippi Academy of Sciences 23:39-45. Hossler, F. E., J. R. Ruby and T. C. Mcllwain. 1979. The gill arch of the mullet, Mugil cephalus. I. Surface Ultra- sturcture. Journal of Experimental Zoology 208(3): 379-397. , J. R. Ruby and T. D. Mcllwain. 1979. The gill arch of the mullet, Mugil cephalus. II. Modification in surface ultrastructure and Na, K-ATPASE content during adaptation to various salinities. Journal of Exper- imental Zoology 208(3):399^405. Krishnamoorthy, R. V., A. Venkataramiah, G. J. Lakshmi and Patricia Biesiot. 1978. Changes in lipid and sterol levels as oysters Crassostrea virginica (Gmelin) approach market size. Ninth Annual Meeting World Mariculture Society pp. 567 576. , A. Venkataramiah, G. J. Ukshmi and P. Biesiot. 1979. Effects of cooking and of frozen storage on the cholesterol content of selected shellfish. Jo urnal of Food Science 44(1):314-315. Lanning, F. C. and L. N. Eleuterius. 1978. The ash and silica of the salt marsh rush, Juncus roemerianus. Gulf Research Reports 6(2): 169-172. Laroche, J. L. and S. L. Richardson. 1979. Winter-spring abundance of larval English sole, Parophrys vetulus, between the Columbia River and Cape Blanco, Oregon, during 1972—1975, with notes on occurrences of three other pleuronectids. Estuarine and Coastal Marine Science 8:455-476. A Summary report 337 Lawler, A. R. 1978. Trichodinella lawleri Lom and Haidar, 1977, causing deaths of pinfish in aquaria. Drum and Croaker 18(2): 1-3. , John T. Ogle and Chad Donnes. 1978. New hosts for lymphocystis. Gulf Research Reports 6(2): 183— 184. _ and Steven L. Shepard. 1978. Procedures for eradication of hydrozoan pests in closed-system mysid culture. Gulf Research Reports 6(2): 1 77- 1 78. and Steven L. Shepard. 1978. A bibliography of the Rhizocephala (Crustacea: Cirripedia). Gulf Research Reports 6(2): 1 53— 1 67 . . 1979. North American fishes reported as hosts of Amyloodinium ocellatum (Brown, 1931). Drum and Croaker 1 9( 1) : 8- 1 4 . Lofton, S. R. and D. W. Cook. 1978. Evaluation of the agar plate procedure for IMViC typing of fecal coliforms isolated from seafoods. Proceedings of the Third Annual Tropical and Subtropical Fisheries Technological Confer- ence of the Americas. TAMU SG 79-101:88-93. Lytle/Thomas F. and Julia S. Lytle. 1979. Sediment hydro- carbons near an oil rig. Estuarine and Coastal Marine Science 8(7):6 19-626. Lytle, J. S., T. F. Lytle, J. N. Gearing and P. J. Gearing. 1979, Hydrocarbons in benthic algae from the eastern Gulf of Mexico. Marine Biology 5 1(3): 279 288. Nicavich, J. M., A. Clem, L, Muga and H. S. Plendl. 1978. Heavy ion identification using a thin Film scintillator detector. Nuclear Instruments and Methods 1 57:93—98. Ogle, J. T., S. M. Ray and W.J.Wardle. 1978. The feasibility of suspension culture of oysters ( Crassostrea virginica) at a petroleum platform off the Texas coast. Contributions to Marine Science 2 1 :63— 76. Otvos, Ervin G. 1978. Calcareous benthic foraminiferal fauna in a very low salinity setting, Lake Pontchartrain, Louisiana. Journal of Foraminiferal Research 8(3): 262-269. . 1978. New Orleans-South Hancock Holocene barrier trends and origins of Lake Pontchartrain. Trans- actions of the Gulf Coast Association Geological Societies 28:337-355. _____ . 1978. Origins of Fisherman Island: Reply. Bulletin of the Geological Society of America 89(12): 1786. . 1979. Barrier island studies, Misslssippi-Alabama Gulf Coast. Proceedings of the First Conference on Sci- entific Research in the National Parks 1 -.781-785. and W. A. Price. 1979. Problems of chenier genesis and terminology — an overview. Marine Geology 20: 251—268. Overstreet, Robin M. 1978 .Marine Maladies? Worms, Germs, and Other Symbionts from the Northern Gulf of Mexico. Mississippi-Alabama Sea Grant Consortium, MASGP- 78-021. 140 pp. . 1978. Trypanorhynch infections in the flesh of sciaenid Fishes. Marine Fisheries Review 40(10):37— 38. and Richard W. Heard. 1978, Food of the Atlantic croaker, Micropogoniasundulatus, from Mississippi Sound and the Gulf of Mexico. Gulf Research Reports 6(2): 145-152. and Richard W. Heard. 1978. Food of the red drum, Sciaenops ocellata, from Mississippi Sound. Gulf Research Reports 6(2): 131—135. Pequegnat, Linda H. and Richard W. Heard. \919.Synalpheus agelas, new species of snapping shrimp from the Gulf of Mexico and Bahama Islands (Decapoda: Caridea: Alphc- idae). Bulletin of Marine Science 29( 1 ): 1 1 0- 1 1 6. Richardson, S. L. and W. Stephenson. 1978. Larval fish data: a new approach to analysis. Oregon State University, Sea Grant College Program Publication ORESU— T— 78— 002, 16 pp. and W. A. Laroche. 1979. Development of the rockfishes Sebastes crameri, Sebastes pinniger , and Sebastes helvomaculatus (Family Scorpaenidae) off Oregon. Fishery Bulletin, U.S , 77(1): 1 -46. Stapp, Dennis S. 1978. A method of thermal structure prediction for estuaries. Journal of the Mississippi Acad- emy of Sciences 23:52—57. Taft, Stephen J. and Richard W. Heard, III. 1978. Aspects of the larval development of Ophthalmophagus sp. (Trematoda: Cycloeoelidae). 77 le Journal of Parasi- tology 64(4):597— 600. Venkataramiah, A.> D. W. Cook, P. Biesiot and GJ. Lakshmi. 1978. Nutritional value of high marsh grass and shrimp shell waste for commercial brown shrimp (Penaeusaztecus Ives), Proceedings of the Ninth Annual Meeting World Mariculturc Society pp. 217—224. Walker, W. W., A. R. Lawler and W. D. Burke, 1979. Acute toxicity of 3— Chloro-4-Methyl benzeneamine hydro- chloride to shrimp and crabs. Bulletin of Environmental Contamination and Toxicology 2 1(41 5): 643 -651. ABSTRACTS Brooks, Daniel R. 1978. Evolutionary history of the cestode order Proteocephalidea, The ASB Bulletin 25(2):61-62. Cake, E. W., Jr. 1979. Infections of Tylocephalum in com- mercial oysters and three predaceous gastropods of the eastern Gulf of Mexico. Proceedings of the National Shellfisheries Association 69:1- Cook, D. W. and S. R. Lofton. 1979. Freezer storage of whole blue crabs for use in picking plants. Abstracts of the Fourth Annual Tropical and Subtropical Fisheries Technological Conference of the Americas. ______ and T. E. Snazelle. 1979. Pigment production by mutants of Bacillus cereus grown on seawater media. Abstracts of the Annual Meetmg of the American Society fur Microbiology 1-89:109. deMond, John D. 1979. Colonization by amphipods of an artificial reef in the north central Gulf of Mexico. Journal of the Mississippi Academy of Sciences 24(Sup.): 121 . 338 HOWSE Duszynski, Donald W M Mobashir A. Solangi and Robin M. Overstreet. 1979. A bizzare new eimerian from the liver of killifish, Fundulus spp. Southwestern Association of Parasitologists Program and Abstracts Twelfth Annual Meeting, The University of Oklahoma Biological Station, April 19-21, 1979, p. 14. Eleuterius, L. N. 1978. Vegetative reproduction and turn- over in the salt marsh rush, Juncus roemerianus. 41st Annual Meeting , American Society of Limnology and Oceanography Victoria, British Columbia. Hall, Jerry F., 111. 1979. Germination of the salt marsh sedge Scirpus olneyi. Journal of the Mississippi Academy of Sciences 24{Sup.):3. Hawkins, W E., H. D. Howse and T. G. Sarphie. 1979. Ultrastructural observations on the heart of the oyster, Crassostrea virginica (Gmelin). Texas Society for Electron Microscopy Newsletter 1 0( 1 ) : 3 8 . , L. G. Tale, C. A, Foster and T. G. Sarphie. 1979. Acute effects of cadmium on tissues of a marine teleost. Anatomical Record 1 93( 1 ): 1 66. Higgins, George G. 1979. Lake Borgne: Volume, surface area and bathymetric statistics. Journal of the Mississippi Academy of Sciences 24(Sup.):43. Johnson, Robert R. 1979. Occurrence of drift disseminules on Mississippi and east Louisiana barrier islands. Journal of the Mississippi Academy of Sciences 24(Sup.): 1 1 . Lytle, Julia S. and Thomas F, Lytle. 1979. Hydrocarbon synthesis and uptake by marsh plants. Journal of the Mississippi Academy of Sciences 24(Sup.):30. McGraw, Katherine A. 1979. Growth and survival of hatchery-rearea and wild oyster spat in Mississippi Sound and adjacent waters. Proceedings of the National Shellfisheries Association 69: 1 Nicovich, J. M., Alex Clem, Luis Muga and H. S. Plendl. 1979. Heavy ion identification using a thin film scintilla- tion counter. Journal of the Mississippi Academy of Sciences 24(Sup.):29, Ogle, John. 1979. Effect of dredging and relaying on oysters in Mississippi Sound. Journal of the Mississippi Academy of Sciences 24(Sup.): 118. Otvos, Ervin G., Jr. 1978. New Orleans South Hancock Holocene barrier trends and originsofLake Pontchartrain. American Association of Petroleum Geologists Bulletin 62(9): 1762. Sky Peck, S. H. and L. N. Eleuterius. 1979. A study of growth and nitrogen content of Spartina alter nif ora and Juncus roemerianus in response to source and concentra- tion of nitrogen. Journal for the Mississippi Academy of Sciences 24{Sup.):7. Stapp, Dennis S. 1979. A thermal structure prediction model for estuaries using a relaxation method. Journal of the Mississippi Academy of Sciences 24(Sup.): 1 02. REPORTS Bond, Marvin T., Dennis D. Truax, Edwin W. Cake, Jr. and David W Cook. 1978, Oyster depuration facility: Engineering assessments. Annual Report, Mississippi- Alabama Sea Grant. MASGP-78— 038. 92 pp. Cake, E. W., Jr. 1979, The potential effects of a freshwater impoundment on oysters and their associates in the Pascagoula estuary and on certain other commercially important and endangered species which inhabit the lower Pascagoula Basin. Prepared for: Pickering, Wooten, Smith and Weiss, Inc., Engineering and Planning, Green- wood, Mississippi. 43 pp. Cook, D. W. and S. R. Lofton. 1978. Evaluation of methods for long term freezer storage of blue crabs for use in picking plants. Mississippi Marine Resources Council Report, Project No. CO-76-017. Demoran, William J. 1979. Mississippi Oyster Reef Rehabil- itation. Prepared for Mississippi Marine Conservation Commission. Eleuterius, Charles K, 1979. Hydrology of Mississippi Sound north of Petit Bois Pass. Mississippi Marine Resources Council Report, Project No. CO— ST— 78 -01 6. Eleuterius, L. N. 1979. A phytosociological study of Horn and Petit Bois islands. Final report for the National Park Service (with two color coded vegetational maps inserted in packet on inside back cover). Final Report, National Park Service Contract No. CX500060993. Ilowse, Harold D. 1979. Activities of the Gulf Coast Research Laboratory during fiscal year 1978 79: A summary report. Gulf Research Reports 6(2): 189-208. Lytle, Julia S. and Thomas F. Lytle. 1979. Pollutant trans- port in Mississippi Sound. Quarterly Report. Mississippi- Alabama Sea Grant Consortium Project No, R/ES-3. Lytle, Thomas F. 1978, Trace metals and water quality parameters in Bay St. Louis. Second Quarterly Report, Du Pont, July. . 1978. Trace metals and water quality parameters in Bay St. Louis. Third Quarterly Report, Du Pont, October. _____ . 1979. Trace metals and water quality parameters in Bay St. Louis. Fourth Quarterly Report, Du Pont, January. and Julia S. Lytle, 1979. Pollutant transport in Mississippi Sound. First Quarterly Report, Mississippi- Alabama Sea Grant Consortium, April. Mcllwain, T. C. 1979. Rearing and stocking striped bass Mississippi Gulf Coast. Annual Progress Report. National Marine Fisheries Service Project PL 89-304 AFCS-6— 2, 99 pp. Norris, Donald E., Robin M. Overstreet, Thomas L. Deardorff, Alan C. Fusco and Clayton M. MacConnelL 1979. Com- pletion Report: A survey of selected fishes and shellfishes from the U.S. Gulf of Mexico for larval helminths of potential public health import. FDA Contract No. 223-76-2141. Ogle, John. 1979. Dynamics of selected oyster populations. Quarterly Progress Report to the Mississippi Bureau of A Summary Report 339 Marine Resources. Contract No. CO-ST-79-Q18. 4 pp. Overstreet, Robin M. 1979. Completion Report: Parasites of commercially important fishes. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Commercial Fisheries Research and Development Act (PL 88-309) Project No. 2-262— R. . 1979. Completion Report: Handbook of Marine Parasites of the Northern Gulf of Mexico. Mississippi- Alabama Sea Grant Project No. 78 028. January 1, 1977 to June 30, 1978. Richardson, S. L. 1979. Final Report: Cooperative billfish study. Department of Commerce, National Oceanic and Atmospheric Administration, Mississippi-Alabama Sea Grant Program Project R/LR-1 1. Gulf Research Reports Volume 6 | Issue 3 January 1979 Macrobenthos of Simmons Bayou and an Adjoining Residential Canal James T. McBee Gulf Coast Research Laboratory Walter T. Brehm Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.01 Follow this and additional works at: http://aquila.usm.edu/gcr ifr Part of the Marine Biology Commons Recommended Citation McBee, J. T. and W. T. Brehm. 1979. Macrobenthos of Simmons Bayou and an Adjoining Residential Canal. Gulf Research Reports 6 (3): 211-216. Retrieved from http://aquila.usm.edu/gcr/vol6/iss3/! This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua. Cromwell(2)usm.edu. Gulf Research Reports, Vol. 6, No. 3, 211216, 1979. MACROBENTHOS OF SIMMONS BAYOU AND AN ADJOINING RESIDENTIAL CANAL J AMES T. Me BEE AND WALTER T. BREHM Ecology Section, Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ABSTRACT Species composition, abundance and seasonal variations of benthic macroinvertebrates in Simmons Bayou, Mississippi, and an adjoining dead-end canal were investigated from July 1976 through June 1977. Cluster analysis of the data summed over five stations indicated four major time periods: July, August -November, December -February, and March -June. Polychaetes and oligochaetes were most abundant in the winter and spring, amphipods in the summer, and chironomids in the spring. Temporal changes in abundance of polychaetes, oligochaetes, and chironomids appeared to reflect seasonal reproductive cycles. The peak in amphipod density corresponded with dense growths of Ruppia maritima. Within the dead-end canal, poor water quality and reduced infaunal densities appeared to be limited to the deeper water behind the sill. INTRODUCTION In recent years the Mississippi Gulf Coast has experienced a rapid growth in human population. Accompanying this growth has been an increased demand for residential and recreational waterfront property. Because such property is in short supply, regulatory agencies have received increased numbers of requests for permits to dredge canals through marsh lands to provide open water access to one or more homesites. These proposed canals are usually dead ended. Regulatory agencies require sound biological information to determine if the proposed alterations would be detrimental to the environment. For the coastal areas along the north- eastern Gulf of Mexico this information is largely lacking. Available studies on coastal canals from the area (Paulson et al. 1974, Paulson and Pessoney 1975) concentrate on hydrology and plankton with the benthos given only cursory attention. The purpose of this project was to study the bottom- dwelling macromveitebrales in a dead-end residential canal and in the nearby natural waterways. Comparisons of species composition of macrobenthos from the natural waterway were made with that from the canal. Seasonal variations of the benthos from the area were also investigated. AREA DESCRIPTION The study site was located in Simmons Bayou, a part of the Davis Bayou system, which empties into the Mississippi Sound near the mouth of Biloxi Bay (Figure I), Water movement in the study area resulted primarily from tidal action with some freshwater runoff occurring during periods of heavy rainfall. Five stations were cstablished-two in a natural bayou, two in a dead-end canal, and one in a dredged area of Simmons Bayou. Benthic samples and hydrological data were collected 17 times at these five stations at intervals of 17 to 31 days, from July 1976 through June 1977. Stations 1 and 2 were located in an unnamed natural bayou. This bayou meanders through diJuncus marsh and is connected to Simmons Bayou at both ends. Water depths at Manuscript received June 6, 1979; accepted July 31, 1979. these stations ranged from 30 to 120 cm depending on the state of the tide and direction of the wind. Stations 3 and 4 were located in a dredged dead-end canal. Permanent residences and small fishing camps border the west side and the south end of the canal. A small fringe area of marsh grasses and bushes borders the east bank. Water depth at the mouth was reduced by a sill. Station 3 was located near the upper end of the canal with water depths of 120 to 185 cm. Station 4 was located near the mouth of the canal on top of the sill in water depths of 30 to 120 cm. Station 5 was located in a portion of Simmons Bayou which was dredged through the marsh about 1 5 years ago . The south bank is an upland area covered with pine trees. and dense underbrush while the north bank borders a large marsh area. Samples were taken in water depths of 60 to 1 50 cm. Samples at stations 1, 2, 3, and 4 were taken in mid- channel. At station 5, samples were taken along the north bank. At all stations the substrate was sandy mud with considerable organic detritus. MATERIALS AND METHODS Measurements of temperature and dissolved oxygen were made with a Yellow Springs Instrument Co. Model 57 oxygen meter. Salinities were measured with an American Optical Goldberg refractometer. Benthic samples were collected with a 15.3 x 15.3 cm Ekman grab mounted on a 1 .5 m handle. A single bottom sample was collected at each station during each sampling period. The sediment was washed into a 0.52 mm screen with fresh water, the residue preserved with 10% formalin and stained with rose bengal. Benthic organisms were hand sorted from the screened residue under an illuminated magnifier, identified, counted, and stored in 70% ethanol. Cluster analyses, using the Bray- Curtis dissimilarity index and flexible sorting (Stephenson 197 2), were used to compare stations to investigate temporal changes. The “cluster intensity coefficient” 0 was set at the now conventional value of -0.25 (Boesch 1973). 211 212 McBee AND Brehm Figure 1 . Area map and station locations. Macrobenthos of Simmons Bayou 213 RESULTS AND DISCUSSION TABLE 1 . Continued During the study 16,115 organisms representing 45 taxa were collected. Of these taxa, 34 Were, identified to genus or species level (Table 1). This list includes a saccoglossan, Elysia chlorotica, and a turbellafian, Canatellia sp., not previously reported from Mississippi. The range of the sabellid polychaete Manayunkia speebsa was extended to the Gulf of Mexico (Brehm 1978), TABLE 1. Benthic fauna found in Simmons Bayou and an adjacent dead-end canal. Phylum Cnidaxia Class Hydrozoa unidentified hydrozoan species Phylum Ptatyhelminthes Class TurbdJaria Canatellia sp. Phylum Rhynehocoela Class Anopla Micrura leidyi (Verrill) Phylum MoUusca Class Gastropoda Anadara sp. Elysia chlorotica (Agassiz) Hydrobiidae Neritina reclivata Say unidentified nudibranch species Class Bivalvia Macorna mitchelli Dali Rangia cuneata Gray Tegula sp. Phylum Annelida Class Polychaeta Class Oligochaeta Class Hirudinea Capitella capitala (Fabricius) Eteone heteropoda Hartman Hypaniola floridana (Hartman) Laeonereis culvert fWcbstcr) Lumbrineris coccinea (Renier) Manayunkia speciosa Leidy Mediomastus ealiforniensis Hartman Parandalia americana Emerson & Fauchald Polydora ligni Webster Stenoninereis martini Wesenberg-Lund Streblospio benedicti Webster unidentified oligochaete species unidentified hirudinid species Phylum Arthropoda Class Insecta unidentified chaeoborinc species unidentified chironomid species unidentified corixid species Class Crustacea Almyracunia sp. Ampelisca abdita Mills Callinectes sapidus Rath bun Corophium louiaianum Shoemaker Cyathura polita (Slimpson) Edotea niontosa (Stimpson) Eurytemora sp. Gammarus mucronatus Say Grandidierella bontiieroides Stephensen Hargeria rapax (Hargcr) Macro Cyclops sp. Melita nitida Smith Parametopella cypris (Holmes) Penacus aztecus Ives unidentified harpacticoid species unidentified inysidacean species unidentified ostracod species Hydrological Data Bottom water temperatures, salinities, and dissolved oxygen concentrations at stations 1, 2, 4, and 5 were simi- lar throughout the study (Figure 2). Although temperatures and salinities at station 3 approximated the other stations for eight months of the study, these parameters were appre- ciably higher at station 3 than at the other stations from November through March. During this period the salinities of the bottom water were as much as 13°/oo higher than the surface readings and bottom water temperatures were up to 6°C warmer than the surface layers. This indicates that the water column at station 3 was stratified from November through March. The dissolved oxygen concentrations of the bottom waters were always lower at station 3 than at the other stations (Figure 2). These differences were greatest from November through March when the water column was stratified. Seasonal Effects Cluster analysis of the species data summed over the five stations for each collection period indicated strong seasonality (Figure 3). There was a summer (July), a late summer-fall (August— November), a winter (December- February), and a spring period (March— June). Differences between the seasons were due to changes in abundance of polychaetes, oligochaetes, amphipods, and chironomids (Table 2). Polychaetes and oligochaetes were most numerous in the winter and spring, arnphipods were most abundant in the summer, and chironomids exhibited their greatest density in the spring. Temporal divisions noted in this study appeared to reflect changes in species composition associated with sea- sonal spawning cycles of benthic macroinvertebrates. The recruitment of large numbers of juveniles during the winter and spring indicated spawning occurred during the cooler months. Tenore (1972) attributed vast seasonal changes in species composition and density in the Pamlico River 214 McBee AND BREHM Figure 2. Bottom water temperature, salinity and dissolved oxygen in Simmons Bayou. Solid line represents mean and range of values for stations 1 , 2, 4, and 5. Broken line represents station 3. Macrobenthos of Simmons Bayou 215 estuary to settling of juvenile forms during the fall and spring. Boesch (1973) reported that many species in Chesa- peake Bay successfully spawn during both spring and fall, and others may be more suc- cessful only in one of the sea- sons. The data presented here indicate a pattern similar to the findings of Tenore (1972) and Boesch (1973). The amphipods had their greatest recruitment d uring the cooler months but the abun- dance of these organisms in the summer appeared to be influenced by the amount of aquatic vegetation. During July dense growths of the sub- merged aquatic angiosperm Ruppia maritima were pres- ent throughout Simmons Bayou* especially at stations 1 and 2.T heRuppia died back in the fall and was not observed again during the study. Appar- ently this aquatic plant pro- vided a favorable habitat for the amphipods, thus they were able to maintain high population densities (10419/m 2 ) through part of the summer. Amphipod abundance dropped drastically during the fall, along with the disappearance of the Ruppia. TABLE 2. Mean density in individuals/m 2 of selected faunal groups during each season at Simmons Bayou. Summer 2 July- 20 July Late summer- Fall 4 August- 1 November Winter 1 December- 22 February Spring lSMarcli- 16 June Polychaetes 1,550 4,219 34,961 14,510 Oligochactcs 3,660 4,951 22,260 14,897 Amphipods 10,419 603 6,114 8,181 Chironomids 2,024 86 1,765 7,879 Station Differences Cluster analysis of species data summed for all collections (Figure 4) indicated that stations 1, 2, 4, and 5 were rela- tively similar to each other and very dissimilar to station 3. This large degree of dissimilarity was due to the greatly reduced number of species and individuals at station 3. Total densities of the benthic infauna were relatively high for stations 1,2,4, and 5 and greatly reduced at station 3 (Table 3). In fact, during the entire sampling period only 140 individuals, representing 17 species, were collected at station 3. This compares with approximately 45 species and 4,000 individuals at each of the other stations. Biological studies of multi- branched heu sing-development canals from other areas indi- cated that species composition and abundance of benthic organisms were detrimentally affected due to highly organic sediments and reduced water quality (Taylor and Saloman 1968, Barada and Partington 1 972, Gilmore and Trent 1 974, Lindall and Trent 1975). Although the canal system in this study was relatively short and unbranched, its overall effect appeared to be very similar to other canal systems. Densities of macroinverte- brates at station 3 were significantly lower (<* = .01) than TABLE 3. Comparison of density, in organisms/m 2 , of benthic macroinvertebrates of Simmons Bayou stations. Date Station 1 Station 2 Station 3 Station 4 Station 5 2 Jul 76 129 22,174 0 5,425 646 20 Jul 258 3,229 301 2,928 1,076 9 Aug 388 7,621 258 1,249 3,961 27 Aug 1,076 5,425 43 2,540 2,239 13 Sep 344 3,832 0 2,339 4,349 4 Oct 474 2,411 0 1,464 1,722 1 Nov 2,583 3,229 646 775 4,047 1 Dec 13,476 17,222 2,368 8,783 7,233 22 Dec 19,806 19,332 732 9,343 7,406 14 Jan 77 36,296 34,617 86 31,689 9,171 2 Feb 40,214 20,408 344 32,248 12,056 22 Feb 21,528 37,200 646 16,921 11,840 15 Mar 22,475 9,558 0 10,032 12,529 14 Apr 7,276 4,133 43 10,549 16,103 5 May 1,464 5,51 1 0 14,338 5,769 25 May 5,554 5,296 172 5,985 15,845 16 Jun 2,885 2,411 388 3,100 32,206 the other stations (Table 3). Although densities at all stations increased during the cooler months due to recruitment, this RELATIVE DISSIMILARITY 0.5 1.0 I I ) Figure 3. Clustering of com- bined stations by collection period using Bray-Curtis dis- similarity index and flexible sorting. RELATIVE DISSIMILARITY 0.5 1 .0 r - I I Figure 4. Clustering of com- bined collection periods by station using Bray-Curtis dis- similarity index and flexible sorting. 216 McBee and brehm period coincided with stratification of the water column in the dead-end canal and total densities at station 3 never reached those of the other stations. Apparently the larvae were either unable to settle at station 3 due to the reduced circulation and stratification or they did not survive because of the low dissolved oxygen content of the water. The area of poor water quality and reduced infaunal densities in the dead-end canal appeared to be limited to bottom areas behind the sill. Hydrographic measurements (Figure 2), infaunal densities (Table 3), and the results of the station clustering (Figure 4) indicated that the unfavor- able environmental conditions observed at station 3 did not occur at station 4. This was apparently due to the sill across the mouth of the dead-end canal. The sill acted as a dam, restricting water circulation to the surface layers, and con- tributed to the stratification and stagnation of bottom waters behind it. Thus, station 4, located on top of the sill in the circulating layer, appeared to be unaffected while station 3, located behind the sill in deeper water, had the reduced faunal densities and hydrological characteristics described by Barada and Partington (1972) and Gilmore and Trent (1974) as being typical of dead-end canals. ACKNOWLEDGMENTS The authors wish to thank Dr. Louise Bush for identi- fication of Canatellia sp . ; Drs. Edwin Cake, Adrian Lawler, Thomas Mcllwain and Robert Woodmansce, and Mr. John Steen for their advice and counsel in reviewing the manu- script; and Mr. Jerry McLclland for his help in collecting samples. REFERENCES CITED Barada, W. & W. M, Partington, Jr. 197 2. Report of Investigation of the environmental effects of private waterfront canals. Board of Trustees of the Internal Improvement Trust bund. Tallahassee, Fla. 63 pp. Boesch, D. F. 1973. Classification and community structure of macrobenthos in the Hampton Roads area, Virginia. Mar. Biol. 21(3):226-244. Brehm, W.T. 1978. First Gulf of Mexico coast record of Manayunkia speciosa (Polychaeta: Sabellidae). N.E. GulfSci. 2(1 ) :7 3— 75 . Gilmore, G. & L. Trent. J974. Abundance of benthic macroinvertc- brates in natural and altered estuarine areas. NOAA Tech. Report NMFS SSRF-6V . 13 pp. Lindalf W. & L. Trent. 1975. Mousing development canals in the coastal zone of the Gulf of Mexico: Ecological consequences, regulations, and recommendations. U.S. Natl. Mar. Fish. Serv., Mar. Fish. Rev. 37(1 0): 19-24. Paulson. O. L., G. F. Pcssoney, L, Massey & D. Weaver. 1974 Reconnaissance of the flushing characteristics and water quality in coastal canals of the Gulf of Mexico. Water Resources Research Institute. Mississippi State University, 21 pp. Paulson, O. L. & G. F. Pessoney. 197 5. Residential canals along the Gulf Coast. Water Resources Research Institute. Mississippi State University. 40 pp. Stephenson, W. 1972. The use of computers in classifying marine bottom communities, pp. 463-473. In: R. Fraser (ed.). Oceanog- raphy of the South Pacific. New Zealand National Commission for UNESCO, Wellington, N.Z. Taylor, J. L. & C. H. Saloman. 1968. Some effects of hydraulic dredging and coastal development in Boca Ciega Bay, Florida. U.S. Fish Wild!. Serv., Fish. Bull. 67:213- 241, Tcnore, K. R. 1972. Macrobcnthos of the Pamlico River Estuary, North Carolina. Feat. Monogr. 13 :5 1 -69. Gulf Research Reports Volume 6 | Issue 3 January 1979 Patterns of Suspended Particle Transport in a Mississippi Tidal Marsh System Courtney T. Hackney Mississippi State University Armando A. De La Cruz Mississippi State University DOI: 10.18785/grr.0603.02 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Hackney, C. T. and A. A. De La Cruz. 1979. Patterns of Suspended Particle Transport in a Mississippi Tidal Marsh System. Gulf Research Reports 6 (3): 217-224. Retrieved from http:// aquila.usm.edu/gcr/vol6/iss3/2 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua. Cromwell(2)usm.edu. Gulf Research Reports , Vol. 6, No. 3, 217-224, 1979. PATTERNS OF SUSPENDED PARTICLE TRANSPORT IN A MISSISSIPPI TIDAL MARSH SYSTEM 1 COURTNEY T. HACKNEY 2 AND ARMANDO A. DE LA CRUZ Department of Biology, Mississippi State University , Mississippi State, MS 39762 ABSTRACT The flux of suspended particulate organic detritus (POD) and suspended inorganic detritus (PID) was studied during ten diurnal tidal periods (24-hour) and three semi-diurnal tidal periods (12-hour) between May 1975 and April 1976. The concentration of POD ranged from 1.50 to 19.79 mg/I, while the PID ranged from 3.20 to 99.61 mg/1, There was a net export of POD during four of 13 tidal periods and a net export of PID during five tidal periods. There was a total net movement of 39.32 and 292,51 kg of POD and PID, respectively, into the marsh. On an annual basis, this is equivalent to the addition of 168g/m 2 /yr of detrital material to the marsh. The predictability of POD and PID concentration in the water was good (r 2 of 57.9 and 58.1%) during ebb tide based on nine biological and physical variables. The ratio of POD to total suspended material was 15.9% and constant during the year at all concentrations. Although the marsh may not be an important source of carbon for the estuary, data indicate that the marsh may regu- late the concentration of suspended detritus in the nearby bay by releasing detritus when the detritus concentration in the water is low and by accumulating detritus when this concentration is high. INTRODUCTION The high productivity of tidal marshes and the presence of high concentrations of particulate organic matter in adjacent coastal waters has led to the conclusion that tidal marshes export much of the carbon fixed by vascular plants on the marsh. An early study (de la Cruz 1965) of the trans- port of particulate organic detritus substantiated this initial conclusion. Recent investigations, however, suggest that the export of organic carbon from tidal marshes may not be a general phenomenon(Nadeau 1972;Heinle and Flemer 1976; Shisler and Jobbins 1977; Wood well et al. 1977), while other transport studies support the traditional view of a net detrital export (Heald 1969; Moore 1974; Settlemyre and Gardner 1977). Some variation in detritus transport should be expected among tidal marsh systems which differ in their vegetation, tidal regime (diurnal or semi-diurnal), tidal range, freshwater input from rivers and geographic orienta- tion with respect to the nearby open water and prevailing winds. Factors which might enhance the movement of par- ticulate material on and off the marsh have not been eval- uated with respect to the concentration of particulate material and its subsequent transport in the marsh system. This study examines the concentration of suspended particulate material (organic and inorganic) in a tidal creek draining an irregularly flooded Juncus marsh in Mississippi. The effects of 13 biological and physical variables on the concentration of detrital material during the ebb and flood 1 Research partially supported by grants from the National Sci- ence Foundation, Oceanography Section (NSF No. GA-35715) and from the Mississippi Marine Resources Council (MMRCNo. GR-76- 003). 2 Present address: Department of Biology, University of South- western Louisiana, Lafayette, Louisiana 70504. Manuscript received February 26, 1979; accepted May 22, 1979. stages of the tidal cycle were determined. In addition, the role of tidal marshes and particulate organic detritus in the productivity of estuaries was reexamined based on the current investigations and on the basis of recent works by other investigators. STUDY AREA The study area is located on the southeastern end of a deltaic island deposited by the Jourdan River. The marsh island is on the western side of St. Louis Bay in Hancock County, Mississippi (Figure 1). The study area included 5,84 ha of watershed drained by a small creek which in turn empties into Catfish Bayou. The creek channel is 95 m long, 3nd 4 to 6 m wide along most of its length. The creek channel has steep banks, but is not deeper than 1 m during mean low tide. The upper reaches of the creek are shallow (less than 20 cm) during low tide and are characterized by very soft bottom sediments, while areas of the creek near the mouth have firm mud substrates. The creek never drains completely, even during the lowest tides. A small bar at the mouth of the creek retains water in the creek when the water level is lower in the adjoining bayou. MATERIALS AND METHODS Hydrology A survey of the study area was made on February 21 and 22, 1975, and the elevation of the marsh was determined to the nearest 2.6 cm using standard survey equipment. The watershed of the study creek was determined by finding the highest point between the study creek and other nearby bodies of water. Where no elevated areas existed, the water- shed was estimated by including half of the area between the study creek and the body of water in question. The volume of water moving in and out of the creek was 217 218 Hackney and De la Cruz Figure 1. The western side of St. Louis Bay showing the marsh island on which the study area is located. Insert shows the location of the Wolf and Jourdan rivers relative to St. Louis Bay. determined by two methods. When the tidal height was above the creek banks, adequate water currents were present and a current meter (Weathermeasure Corporation Model F-582) was used to directly measure water flow. The current was measured approximately 20 cm below the surface. The current meter was accurate to ± 0.02 -0.05 m/s within the current range observed. The volume of water was calculated by multiplying the current velocity by the cross sectional area of the creek at the point of measurement. The cross sectional area of the creek was determined by measuring the depth of the creek every 0,5 m across the mouth of the creek and graphically producing an area of the mouth’s cross section for any level of water based on a permanent tidal gauge in the creek. For every unit (cm) increase or decrease of the tidal height the cross sectional area of the creek changed correspondingly. When the water level was below the creek bank, no measurable current was present. Water movement was determined by changes in the volume of water present in the creek. This was determined by measuring the cross sectional area of the creek at represent- ative points and determining the volume of the creek at any given tidal height, using a permanent tidal gauge located within the creek as a reference point. Thus, a 1-cm change of water level was accompanied by a known volume change at any point in the tidal cycle. The volume of water entering or leaving the creek is important in the calculation of net import or export of suspended materials during a tidal cycle. The weak diurnal tides along the Mississippi Gulf coast seldom return to the same level at the end of a tidal cycle. A suspended particu- late matter budget which does not account for this differ- ence would be inaccurate, although over many collections the bias is not important. An example of the calculations used to determine this correction factor may be found in Hackney (1977). Values reported here are the actual trans- port values although the corrected values are also reported for seasonal comparisons. It is assumed in all the calculations that the current was uniform across the entire cross sect ion of the creek, and that the concentration of suspended particulate material passing Particulate Material Transport 219 the collecting station was uniform during the specified time interval and with respect to depth and width. During the study, salinity, temperature and dissolved oxygen concentration of the water were measured in situ 20 cm below the surface every hour. Salinity was measured with a Yellow Springs S~C— T (salinity-conductivity- temperature) meter (Model 33), precise to ±0J°/oo. Dis- solved oxygen was measured with a Yellow Springs oxygen meter (Model 54), precise to +1% , Temperature was measured with a thermister attached to the oxygen meter and precise to ±1%. Three 1.22 m 2 pull-up traps (Higer and Kolipinski 1967) with 3.1 mm mesh were placed in the creek in March 1975. One net was installed along the south end of the creek approximately 22 m from the mouth, while the second and third traps were placed in the middle of the crock 70 and 92 m from the mouth. Collections were always made during ebbing tide at approximately the same water height during a tidal cycle as indicated by a permanent tidal gauge. One collection consisted of pulling each of the three nets on two successive days following the transport study. No reduction in catch was noted on the second day. These data provided information on the numbers and biomass of organ- isms in the creek during each transport study. A measure of the movement of organisms into and out of the creek was obtained by placing a 3.1 mm mesh bag seine across the entrance of the tidal creek. The bag stretched across the creek from the surface to the botiom. Organisms were removed during high slack tide and low slack tide. Although this technique was selective for smaller organisms (crabs and shrimp), it provided information on animal movements into and out of the creek. Suspended Paniculate Material Water was collected 20 cm below the surface every 2 hours during each of 13 tidal periods from May 1975 to April 1976. The collection for January 1976 was made on February 5, 1976. Samples were collected from two consecu- tive semi-diurnal (12-hour) tidal periods on September 19 and 20, 1975, and one on February 5, 1976. Water was col- lected in 44iter plastic jugs and preserved in 1% formalin solu- tion to prevent agglutination and bacterial decomposition of the suspended particulate organic detritus. Preservation did not alter the analytical results since prior testing with preserved and unpreserved samples did not differ with respect to combustible carbon (ANOVA [analysis of variance] at a - 0.05). Water samples were brought to the laboratory and filtered through a Gelman Type A glass filter (0.3 pm porosity) following the procedure of Golterman (1 969), with modifi- cation for the glass filters. The results are reported as the weight of oxidizable material (particulate organic detritus, POD) per liter of water and as the weight of nonoxidizable materia] (particulate inorganic detritus, PID) per liter of water, Golterman (1969) notes that the loss of bound water from clays in the PID is negligible. Appropriate corrections were made for the addition of formalin and for filter weight loss during ashing. RESULTS Transport The concentration of total suspended particulate material ranged from 4.6 to 119,4 mg/1. The oxidizable fraction, suspended POD, ranged from 1.5 to 19 ,7 mg/1 while the PID ranged from 3,2 to 99,6 mg/1. Concentrations between 12.0 and 36.0 mg/1. 2.0 and 4.5 mg/1 and 6.0 and 30.0 mg/I for total suspended material, organic fraction and inorganic fraction, respectively, were more common. There was a net export of suspended POD during four of the 13 tidal periods and a net export of PID during five tidal periodsfTable 1). Because of the variability in tidal Hushing, the amount of suspended materials exchanged varied greatly from tidal cycles in which there was little net exchange to cycles in which more than 167 kg of suspended materials were exchanged (Tabic I). The concentration of both POD and PID was always highest near low tide (Figure 2). Very little water exchange occurred during the lowest part of the t idal cycle. Incoming water filled only the tidal creek channel. Increased water How and volume of water moving into or from the marsh occurred during the flood portion of the tidal cycle. Thus, actual exchange was determined more by concentrations of detritus at higher tide levels; for example, from 1500 to 2000 hours and from 0400 to 1200 hours (Figure 2) during tire May 1975 sampling. There was a total net flux of 39 kg of POD and 293 kg of PID into the marsh during the 13 tidal cycles studied. Most of the tides which exported detritus occurred during the summer, while detritus was imported during most of the rest of the year. There were 385 tidal cycles (Tide Tables 1975, 1976) during the 12-rnonth study of detrital flux. Data from the 13 tidal cycles studied were integrated based on this information. More than 1 164.5 kg of POD and 8662.8 kg of PID were estimated to have been added to the 5.84 ha area of marsh drained by the small tidal creek. This is equivalent to the addition of 168 g of detrital material per m 2 per year. Fauna Thirty-two species of fish and four invertebrate species were collected. The winter fauna was dominated by Fundulus grand is and Fund ulus confluentus. During the spring and summer Brevnnrtia patronus and An choa mil chilli were very abundant. Palaemnneies pugio was present all year. For more details on the fauna of this area see Hackney (1977). Predictability The export or import of detritus depends on its concen- trations in the water during the ebb and flood tide and on the difference between these two values, assuming equal water volume transport. Jackson (1964) found that 220 Hackney and De la Cruz table i. Summary of particulate detritus budget expressed as kilograms pet tidal cycle. Date Organic Particulate Transport Out In Actual Net Compensated Net 5/27/75 46.603 31.931 -14.670 -14.786 6/28/75 25.839 6.587 -19.252 - 2.397 7/22/75 22.623 29.897 + 7,274 - 7.697 8/30/75 47.364 28.899 -18.465 -10.087 9/19/75 10.370 11.215 -1- 0.845 + 1.226 9/20/75 15.915 18.075 + 2.160 + 5.700 10/24/75 20.127 35.665 +15.538 +16.257 11/21/75 9.256 10.452 + 1.196 + 1.197 12/23/75 1.348 2.791 + 1.443 + 0.603 2/ 5/76 1.624 0.472 - 1.152 - 0.476 2/20/76 15.549 47.475 +31.926 - 1.528 3/26/76 16.529 25.283 + 8.754 + 8.603 4/16/76 28.846 52.579 +23.733 +41.833 Totals 261.993 301.321 +39.328 +38.440 Inorganic Particulate Transport Actual Compensated Date Out In Net Net 5/27/75 112.641 101.406 - 11,235 - 10.978 6/28/75 55.158 16.759 - 38.399 + 2.761 7/22/75 53.289 75.456 + 22.167 - 7.926 8/30/75 123.850 54.815 - 69.035 - 53.386 9/19/75 26.237 31.950 + 5.713 + 6.793 9/20/75 35.980 49.358 + 13.378 + 23.367 10/24/75 61.199 96.547 + 35.348 + 38.563 11/21/75 41.367 37.393 - 3.974 - 3.974 12/23/75 4.069 9.313 + 5.244 + 2.052 2/ 5/76 4.393 1.403 - 2.990 - 1.063 2/20/76 42.664 178.980 + 136.316 + 55.439 3/26/76 45,121 79.101 + 33,980 + 33.525 4/16/76 84.481 250.481 +166.000 + 165.998 Totals 690.449 982.962 +292.513 +251 171 temperature and tidal range affected the concentration of silt in English estuaries. A multiple regression analysis(Draper and Smith 1966) was used to determine the relationship of the dependent variable POD and the independent variables: temperature, salinity, dissolved oxygen, height of the water in the creek, tidal range, volume of water exported or imported during the day, biomass of organisms in the creek, number of these organisms, weight of plant debris moving in and out of the creek, time of day and time of year. This analysis was done separately for the ebb and flood tides. The analyses were repeated with PID as the dependent variable, The relative importance of the variables was determined by a subset selection procedure (Hocking and Leslie 1967), This procedure selected tidal height as the most important variable which explained the variation of POD and PID. 30 * E 20 =3 10 May 27- 28 f 1975 Low Tide _J • PID o POD 1600 2400 HOURS 800 Figure 2. Typical pattern of the concentration of particulate organic detritus (POD) and particulate inorganic detritus (PID) during a tidal cycle. During ebb tide, eight variables explained 57.9% of the variability of the POD and 58.1% of the variability of the PID collected during ebb tide (Table 2). Salinity, dissolved oxygen, temperature, day of the year (a measure of seasonal variation) and number of organisms in the creek were also important variables in explaining the variability of POD and PID. The number of organisms in the creek was also a signifi- cant factor in explaining some of the variability of detrital concentration (Table 2). Variable [7] was the biomass of organisms caught in one pull-up trap collection and variable [8] was the number of organisms caught in the same collec- tion. Although these two variables were based on the same data collection they did not exhibit colinearity. Variable [6] was the number of organisms caught in the bag seine which is 3 measure of their abundance and movement within the creek. Seasonality (time of year), variable [5] , was also important because more organisms were in the creek during certain times of the year (Hackney 1977). The influence of salinity, temperature and dissolved oxygen on detrital con- centration may also occur when these factors interact with the faunal component of the creek and with the season. When the same multiple regression analysis and subset selection procedures (using the same variables) were applied to the flood tide, no variable or combination of variables explained much of the variability of POD or PID. Erken- brecher and Stevenson (1977) noted that ebb and flood particulate Material Transport 221 TABLE 2. Multiple regression model for the concentration of suspended particulate matter during ebb tide and relevant summary statistics. Particulate Organic Detritus (POD) Particulate Nonorganic Detritus (PID) y = -1.1897 + 0.001 1 [5] + 0.01342 [2J 0.04927 (4) y = -6.527 + 0.006292 [5] +0.04668 [21 - 0.1978 [4] + 0.10759 13] + 0.00766 [1] + 0.00100- [6] + 0.4340 [3} +0.0456 [1] +0.00948 19] + 0.00167 [71 - 0.00052 [8) + 0.00028 [61 +0.01082 [7] - 0.00334 [8] x 2 = 0.5701 r 2 = 0.6144 mean square error = 0.01996 mean square error = 0.55018 total sum of squares = 2.5131 total sum of squares = 14.1940 number of observations = 62 number of observations = 62 Variable order selected by subset selection procedure and the cumu- Variable order selected by subset selection procedure and the cumu- lative r values. lative r 2 values. Variable Cumulative Variable Cumulative m 0.1995 [1] 0.3083 [21 0.2418 [91 0.3601 [31 0.3122 [41 0.3959 HI 0.3920 [31 0.4212 [51 0.4649 [5] 0.4739 [61 0.5336 [8] 0.5811 [7| 0.5607 [71 0.5940 [8] 0.5791 [8] 0.5811 [7] 0.5940 waters had distinctly different characteristics in a South Carolina tidal creek and that different biotic and abiotic factors were needed to explain the microbial concentration during ebb and flood tides. The source of suspended particulate detritus appears to be the same for material in ebb and flood waters since no difference between the ratio of particulate organic detritus to total suspended material was noted. A simple linear regression applied to these combined data produced an r 2 of 0.952 for N = 135 (Figure 3). The resultant model (Y = 1.21 + 0.15874X, where Y is the POD and X is the total suspended material) provides a high degree of predictability. The organic material was 15.87% of the total during the study period no matter how high or low the total suspended concentration was in the water. Thus, the similarity of the predictive models for POD and PID is not surprising. The sedimenl on this marsh contains from 4.9 to 13.0%oxidiz- able material (Hackney and de la Cruz 1978) while the intact decaying plant material found on this marsh contains 68 to 93% oxidizable materials (Hackney 1977). This seems to indicate that the source of the suspended detrital material is not directly from decomposition of dead plant material. The similarity between the organic ratio of particulate material in ihe marsh sediment and that of the suspended detritus may indicate that the source of marsh sediment is primarily through the deposition of suspended material, DISCUSSION Existing tidal transport studies of particulate organic detritus do not agree on either the net directional movement or on the percent of the overall vascular plant productivity in this movement. Estimates vary from near 50% net export TOTAL PARTICULATE MATERIAL mg/l Figure 3. Relationship of particulate organic detritus (POD) to total particulate material in the water between May 1975 — April 1976. 222 Hackney and De la Cruz to 6% net imports of particulate organic detritus. Nadeau ( 1 972), Shisler ( 1 975), Heinle and Flemer (1976), Woodwell et al. (1977) and the present study all reported net imports or at least no significant exports of suspended particulate organic detritus; while Teal (1962), de la Cruz (1965), Heald (1969), Day et al. (1973), Nixon and Oviatt (1973), Moore (1974), and Settlernyre and Gardner (1977) reported net exports. Some studies which reported high net exports are based on small data sets or on estimates rather than actual transport data. Only Moore’s (1974) study, which reported net exports of 40% and 28% of the vascular pro- ductivity of two marsh systems, was based on the amount of data reported by Shisler (1975), Heinle and Flemer (1976), and Woodwell et al. (1977), who found net imports. No single factor (he., morphometry, hydrology* etc.) can explain the differences found between marshes with a net annual export and those with a net annual import of partic- ulate organic detritus. All studies were made on tidal creeks except for Heald (1969) who studied a tidal river from which there was a constant supply of fresh water. Detrital export was expected in this system since there was a net export of water. The concentration of particulate carbon in water has been determined by combustion (de la Cruz 1965; Heald 1969) and by analysis in a carbon analyzer (Moore 1974; Shisler 1975; Heinle and Flemer 1976; and Woodwell et al. 1977). Theoretically, there should be little difference between the two techniques. Because each of the references cited used the same technique throughout their study, net exports or imports cannot be attributed to differences in techniques. Other studies (Day et al. 1973; Nixon and Oviatt 1973) report the flux only in terms of a predictive model, obtaining their values by subtracting all other potential pathways of energy loss from the total marsh productivity. This is a good approach, hut until the role of the microbial community in marsh soils is quantified, this technique may overestimate the export. Direct transport studies are deficient because they do not measure all of the tides during the year. The fewer tidal cycles examined, the greater the effect of one atypical tidal cycle on the annual budget. Conversely, the more tidal cycles examined (assuming random sampling), the more closely the estimates of total annual export or import approach the true value and the effect of one atypical day on the overall estimate is minimized. It is possible that some of these previous studies included data collected on atypical days or did not have a random sample of days including days when the weather was poor. When sampling was done on days preceded by fair weather, detrital export was observed in the study creek even though this is not what appears to he the usual pattern. Another approach also provides strong evidence that tidal marshes do not export large amounts of organic material. In Georgia’s estuaries, where a strong case is made by Odum and de la Ciuz (1967) for a nei tidal export of particulate detritus, Haines (1977) noted that the stable carbon isotope ratios of particulate detritus collected in Georgia estuaries did not resemble those of Spartina alterniflnra Stable iso- topic ratios of Spartina carbon are different from the carbon ratios of phytoplankton or terrestrial detritus (Haines 1976). Carbon ratios of the plants are not changed to a significant extent as the carbon moves up the food chain and as it is degraded on the marsh (Haines 1977). The samples were collected from a tidal creek and a tidal river and were separ- ated into five size fractions between 27 and 250 /am. The carbon ratios of all of these samples resembled those of organic matter of terrestrial or phytoplankton origin. Based on this and a mounting body of evidence from transport studies, Haines suggests a “re-examination of the assumption that the bulk of detrital carbon in Georgia’s estuaries is derived from S. al ter ni flora production.” Examination of the sedimentary history of a marsh along with transport studies may be one of the best methods of determining long-term trends. The addition of 4.7 mm/yr organic material to the Flax pond marsh (Flessa et al. 1977) and estimates of the rate of sedimentation (Armentano and Woodwell 1975) substantiates Woodwell et al.’s (1977) con- tention that little carbon is exported from the Flax pond system. Another useful approach may be to examine the transport into and out of the entire estuarine system (Happ et al. 1977), as well as the transport from small creeks draining marshes. This approach requires information on the input of river systems which may be difficult to obtain. More studies are needed to evaluate the dynamics and fate of suspended particulate detritus in the marsh-estuarine system. This study indicated that the amount of inundation of the marsh as reflected in the tidal height (variable [ 1 ] in Table 2), affected the particulate detritus concentration of water leaving the marsh. Therefore, differences in the amount of tidal inundation are suggested as an important factor with respect to particulate detritus transport reported in other studies. Tidal height was a measure of how much and to what extent the marsh was flooded. Tidal height does play a role in removing detritus from the water because marsh plants hinder or slow down the flow of water and produce conditions which may allow suspended material to leave the water column and settle on the substrate (Axelrad 1974). Once this material has settled, the current velocity necessary to resuspend the cohesive particles is greater than the current velocity necessary to transport these particles once they are in suspension. Particles smaller than 0.01 mm require as much current velocity to resuspend them as do particles over 2 mm (Hjulstrom 1939). The effect of the marsh biota may be important, particularly the filter feeders and amphipods as they remove detrital material from the water and deposit this as pseudofeces on the marsh. Many benthic amphipods also use detrital materials in the con- struction of their burrows (Thomas 1975). For this process to occur, water must reach these filter feeders, notably the Particulate Material Transport 223 pelecy pods Pnlymesoda caroliniana and Geukensia demissus, which live on the marsh, Fungi, bacteria and protozoa on the mud surface may be important in retaining detritus on the marsh once it lias settled. Conversely, the larger invertebrates and fishes tend to stir up the sediment. The grass shrimp Palaemonetes pugio and kill! fish, Fmdulus spp., were observed “muddying the water” on many occa- sions during this study. None of these biotic factors can affect the concentration of detritus in the water unless the marsh floods. Tabic 1 indicates the variation of transport due to the irregular flooding that is characteristic of Gulf coast marshes. Factors affecting the particulate detrital concentration of the waters also affect the overall transport of particulate detritus. Amphipods were generally more abundant in tidal marshes during cooler months (Thomas 1975), while fishes and larger Crustacea were less abundant. Most of the cooler months exhibited a pattern of net import of particulate detritus (Tabic 1). Conversely, exports occurred during summer months when the larger fauna were most abundant. The higher concentration of particulate detritus near low tide wasprobably due to the greater concentration of mobile organisms per unit of water. The warmer water temperatures also increased their activity. Other environmental factors also play an important role. Redfiekl (1972) noted that sedimentary material may be carried onto the marsh due to strong winds stirring up sedi- ment in nearby shallow areas. Strong winds produce these conditions in the nearby bay. Heavy rainfall in the nearby watershed thus increases the potential flow of material to the St. Louis Bay system by the Jourdan and Wolf rivers (Figure 1). Locally heavy rainfall during low tides could also increase the detritus load of bay waters. Presumably, imports of detritus onto the marsh arc caused by an increased amount of river-borne detritus in the water surrounding the marsh system. Redfield (1972) suggested that marshes along the eastern coast of the United States are building up at the rate of 2.5 mm/yr. This requires the addition of material. The marsh in the present study appears to have a long-term record of elastics and organic material accumulation as evidenced by recognizable Spartina rhizomes buried 20 to 40 cm below the surface of the Jimcus marsh. Spartina is characteristic of lower areas of this marsh (de la Cruz and Hackney 1977). While it is possible to predict the concentration of partic- ulate detrital material in the water that comes from marshes during ebb tide, based on information on tidal height, physical conditions of the water in the creek, time of the year and the abundance of organisms within the creek, the prediction of the concentration of particulate organic detritus in the water during flood tide is impossible. It probably depends gieatly on the configuration and current patterns of the nearby estuaries and on such random factors as weather conditions and nearby river discharge. This investigation suggests a net import of particulate material onto the marsh. Thus, it appears that high vascular plant productivity may not be the most important function of the marsh relative to the overall productivity of the estu- arine system. Net export of particulate material occurs some- what infrequently and is probably occasioned primarily by low concentrMinn&of particulate detritus in the surrounding bodies of water. The marsh may serve as a holding area for material discharged by rivers, importing material during high river discharge periods and exporting material when that discharge is small. Thus, marshes may act as a control mechanism by removing materials from the water when the concentration of these materials is high in the nearby bays and rivers and then exporting these same materials when the concentration is low. The marshes, then, may dampen oscillations in the concentration of suspended materials in nearby bodies of water. This would tend to produce a more even release of material to offshore waters. Thus, even if a marsh exports very little of its own production as suspended particulate matter, it may be important in the regulation of overall export of material from estuaries. REFERENCES CITED Armentann, T. W. & G. M. Woodwell. 1975. Sedimentation rates in a Long Island marsh determined by 2l0 Pb dating, Limnol Oceangr. 20:452-456. Axelrad, D, M. 1974. Nutrient flux through the salt marsh. Ph.D. diesis. The College of William and Mary. J 34 pp. Day. J. \V., Jr., W. G. Smith, P R Wagner & C. S. Wilmer. 1973. Community structure and carbon budget of a salt tnarsh and shallow bay estuarine system in Louisiana. Publication No. LSU-SG-72-Q4. Center for Wetland Resources, Louisiana Stale Univ., Baton Rouge, LA de la Cruz. A. A. 1965. A study of particulate organic detritus in a Georgia salt marsh-estuarine ecosystem. Ph.D. dissertation. University of Georgia. 10U pp. & C. T, Hackney, 1977. Energy value, elemental com- position and productivity of below ground biomass ol' a Juncus tidal marsh, Ecology 58:1165-1170. Draper, N. R. & H. Smith. 1966. Applied Regression Analysis. John Wiley and Sons, Ine., New York. 407 pp. Erkenbreeher, C. W. & L. H. Stevenson. 1977. Factors related to the distribution of microbial biomass in salt-marsh creeks. Mar. Biol . 40:121-125. Hessa, K.. W., K. J. Constantine & M. K. Cushman. 1977. Sediment- ation rates in a coastal marsh determined from historical records. Chesapeake Sri. 18:172-176. Golterman, H. L, 1969. Methods for chemical analysis of freshwaters. IBP Handbook No, 8, Blackwell Scientific Publications. Oxford, England, 172 pp. Hackney, C. T. 1977. Energy flow in a tidal creek draining an irreg- ularly flooded Juncus marsh. Ph D. dissertation. Mississippi State University. 83 pp. & A. A. de la Cruz. 1978. Changes in interstitial water salinity of a Mississippi tidal marsh. Estuaries 1 : 1 85 188. 224 Hackney and De la Cruz Haines, E. B. 1976. Stable carbon isotope ratios in the biota, soils and tidal water of a Georgia salt marsh, Estuarine Coastal Mar. Sci. 4:609-616. . 1977. The origins of detritus in Georgia salt marsh estuaries. Oikos 29:254-260. Happ, G., J. F. Gosselink &. J. W. Day, Jr. 1977. The seasonal dis- tribution of organic carbon in a Louisiana estuary. Estuarine Coastal Mar. Sci. 5:695-705.' Heald, E. J. 1969. The production of organic detritus in a south Florida estuary. Ph.D. dissertation. University of Miami. 110 pp. Heinle, D. R. & D. A. Flemer. 1976. Flows of material between poorly flooded tidal marshes and an estuary. Mar. Biol. 35:359 -373. Higer, A. & M. Kolipinski. 1967. Pull-up trap: A quantitative device for sampling shallow water animals. Ecology 48: ] QOS 1009. Hjulstrom, F, 1939. Transportation of detritus by moving water. Pp. 5-13 in: P. D. Trask, ed.. Recent Marine Sediments, Tulsa, OK, American Association of Petroleum Geologists. Hocking, R. R. & R. N. Leslie. 1967. Selection of the best subset in regression analysis. Technomelrks 9:531-540. Jackson, \V. H. 1964. Effect of tidal range, temperature and fresh- water on the amount of silt in suspension in an estuary. Nature 210:1017. Moore, K. A. 1974, Carbon transport in two York River, Virginia, tidal marshes. M.A. thesis. University of Virginia. 102 pp. Nadeau, R. J. 1 972. Primary production and export of plant materials in the salt marsh ecosystem. Ph.D. thesis. Rutgers University. 167 pp. Nixon, S. W. & C. A. Oviatt. 1973. Ecology of a New England salt marsh. Ecol, Monogr. 43:463-498. Odum, E. P. & A. A. de la Cruz. 1967. Particulate organic detritus in a Georgia salt marsh-estuarine ecosystem. Pp. 383-388 in: G. H. Lauff, ed., Estuaries. American Association for the Advancement of Science. Washington, D.C. Redfield, A. C, 1972. Development of a New England salt marsh. Ecol. Mo nogr. 42:201-237. Settlemyre, J. L. & L. R Gardner, 1977, Suspended sediment flux through a salt marsh drainage basin. Estuarine Coastal Mar. Sci. 5: 653-664. Shisler, J. K, 1975. Movement of organic carbon in natural and mosquito ditched salt marshes. Ph.D. dissertation. Rutgers Uni- versity, 1 34 pp. ______ &■ D. M. Jobbins. 1977. Tidal variations in the movement of organic carbon In New Jersey salt marshes. Mar. Biol. 40:127-134. Teal, J. M. 1962. Energy flow in the salt marsh ecosystem of Georgia. Ecology 43:614-624. Thomas, J, D. 1975. Garnmarid amphipods of the Barataria Bay, Louisiana region. M.S. thesis. Louisiana State University. 32 pp. Wood well, G, M., D. E. Whitney & D. W. Juers. 1977. The Flax pond ecosystem study: Exchanges of carbon in water between a salt marsh and Long Island Sound. Limnol. Oceanogr. 22:833-838. Gulf Research Reports Volume 6 | Issue 3 January 1979 An Annotated Key to the Mysidacea of the North Central Gulf of Mexico Kenneth C. Stuck Gulf Coast Research Laboratory Harriet M. Perry Gulf Coast Research Laboratory Richard W Heard Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.03 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Stuck, K. C., H. M. Perry and R. W. Heard. 1979. An Annotated Key to the Mysidacea of the North Central Gulf of Mexico. Gulf Research Reports 6 (3): 225-238. Retrieved from http:/ / aquila.usm.edu/gcr /vol6/iss3/3 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua. Cromwell(2)usm.edu. Gulf Research Reports, Vol. 6, No. 3, 225-238, 1979. AN ANNOTATED KEY TO THE MYSIDACEA OF THE NORTH CENTRAL GULF OF MEXICO KENNETH C. STUCK, HARRIET M. PERRY AND RICHARD W. HEARD Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ABSTRACT An annotated key is provided to 17 species in 11 genera of the order Mysidacea from the north central Gulf of Mexico. All species are illustrated. The occurrence of Bowmaniella dissimilis is reviewed in light of Holmquist’s 0975) renaming of B, dissimilis sensu Brattegard (1970). Reports of several species of Metamysulopsis are discussed. The possible hybridization of two species of Taphromysis is considered, INTRODUCTION With the exception of the decapod crustaceans, few com- prehensive keys exist to the estuarine and marine inverte- brate fauna of the north central Gulf of Mexico. Expansion of research efforts in the fields of ecology, fisheries biology and toxicology have increased the need for basic systematic reviews of many invertebrate groups. The authors intend to publish a series of illustrated keys to selected groups of Crustacea that will facilitate identification of local fauna. All descriptions and illustrations in the following key repre- sent original work, with the exception of Figure 1 . Peracaridans of the order Mysidacea are small shrimp-like organisms found in a variety of habitats. They may be part of the benthos, meroplankton or holoplankton, but most are typically hypoplanktonic. The majority of the species Manuscript received July 26, 1979; accepted August 16, 1979. are neritic, with both freshwater and marine representatives known. A side and dorsal view of a typical mysid is illustrated in Figure 1. The thorax is covered by a carapace which is not united with the last four thoracic segments. The first thor- acic segment is united with the head. Anteriorly, the cara- pace may project into a rostrum. The antcnnules are bira- mous. The antenna has a large scale-like exopod. The eyes are usually stalked, but in the genus Pseudomma, they are fused into an ocular plate that extends across the anterior margin of the carapace. The mouthparts consist of a pair of mandibles and two pairs of maxillae. The first, and occasionally the second, pair of thoracic appendages may be modified asmaxillipeds.The six or seven remaining thoracic appendages are biramous with filamentous exopods that sometimes bear swimming setae; some may have subchelate endopods. In the females, two or three antennule antenna antennal scale dorsal process statocyst 8 1 * 1 thoracic limb pleopods abdominal segments Figure l. Side and dorsal view of a typical mysid (modified from Smith, 1964). 225 226 Stuck et al. pairs of oostegites form a subthoracic marsupium to brood eggs. Mysidsare sexually dimorphic. The abdominal appendages or pleopods are rudimentary in females and developed in males. In the genus Bowrrumiella these abdominal append- ages are distinctive, with the third pleopod of the male bearing a large, complex copulatory organ. A pair of biramous uropods are located on either side of the teison, with the inner ramus bearing a bead-like statocyst. Many mysidaceans are filter feeders and some species use the second maxilla to produce a current and trap food; others are carnivores. A few forms are scavengers. Neritic and marine species often occur in large swarms and provide valuable forage for many fish. To date, about 460 species have been reported through- out the world. KEY TO THE MYSIDACEA OF THE NORTH CENTRAL GULF OF MEXICO 1 . Eyes fused, forming a large ocular plate extending across anterior margin of carapace (Fig. 2 e) Pseudomma sp. (Page 233) Eyes not fused into an ocular plate, supported on separate eyestalks 2 2. Distal end of teison emarginate (slightly indented), concave or deeply cleft (Fig. 5a— d, g, i, k, 1, p-s) 3 Distal end of teison convex, linguiform in appearance, without terminal cleft or emargination (Fig. 5f,h,j,m-o) ... 11 3. Antennal scale with lateral tooth present (though sometimes minute), devoid of setae on outer margin (Fig. 3a— d, 0 4 Antennal scale without lateral tooth, setae present on both inner and outer margins (Fig. 3g,i,k,o-q) 6 4. Each apical lobe of teison armed with 1 large spine (Fig. 5a); antennal scale small and rounded in appearance; sympod of antennal peduncle with large barbed projection on its inner distal corner (Fig. 3 a) . . . . Anchialina t ypica (Page 227) Each apical lobe of teison armed with 2 large spines (Fig. 5b— d); antennal scale of moderate size, more elongate; sympod of antennal peduncle without large barbed projection on its inner distal corner 5 5. Posterior margin of fifth abdominal segment with dorsal process (Fig. 1); outer uropod armed with 18 or more lateral spines; inner uropod armed with 5 or more large spines along medial margin, without small spines near statocyst (Fig. 4c, d) BowmanicUa spp. (Page 232) {Bowmaniellu hrasilicnm and BowmanicUa Jloridaria) Posterior margin of fifth abdominal segment without dorsal process; outer uropod armed with 16 or less lateral spines; inner uropod armed with 3 or 4 large spines along medial margin, 5 to 7 small spines near statocyst (Fig. 4b) .... BowmanicUa portoricensis (Page 227) 6. Terminal cleft or emargination devoid of spines on its inner margins (Fig. 5g, k, l) 7 Terminal cleft or emargination armed with spines or laminae (flat spine-like projections) (Fig, 5i, p-s) 8 7. Proximal one fourth of lateral margin of teison unarmed; terminal cleft moderately deep (Fig. 5g) Promysis atlantica (Page 234) Entire lateral margin of teison armed with spines; distal end with shallow emargination between large inner pair of spines (Fig. 5k, 1) Mvsidopsis / urea (Page 235) 8. Lateral margin of teison armed with 8 to 20 spines (Fig. 5p— s) 9 Lateral margin of teison armed with 25 or more spines (Fig. 5i) Bathymysis renoculata (Page 235) 9. Proximal half of lateral margin of teison devoid of spines (Fig. 5p); inner uropod bearing 15 or more spines along medial margin (Figure 4o) Heteromysis formosa (Page 237) Entire margin of teison bearing spines (Fig. 5q-s); inner uropod bearing 1 spine along medial margin (Fig. 4p—r). ... 10 KEY TO MYSIDACEA OF NORTH CENTRAL GULF OF MEXICO 227 10. Anterior margin of carapace with small lateral spine just below base of eyestalk (Fig. 2p) Taphromysis louisianae (Page 237) Anterior margin of carapace without lateral spine (Fig. 2q) Taphromysis bovjmani (Page 237) 1 1 . Antennal scale with lateral tooth (Fig. 3f); terminal portion of telson armed with several large spines on each lateral comer and 3 very small spines medially (Fig. 5f) Siriella thompsonii (Page 234) Antennal scale without lateral tooth (Fig. 3h, j, 1— n); apex of telson variously armed with 2 or more spines (Fig. 5h, j, m o) 12 12. Antennal scale more than 12 times long as wide (Fig. 3n); distal half of telson armed with 40 or more spatulate spines (Fig. 5o) Brasilomysis castroi (Page 236) Antennal scale 8 or less times long as wide (Fig. 3h, j, 1, m); lateral margins of telson armed with nonspatulate spines (Fig. 5h, j, m, n) 13 13. Proximal two thirds of lateral margins of telson devoid of spines; apex armed with 1 pair of spines slightly longer than laterals (Fig. 5h) Metamysidopsis swifti (Page 234) Entire lateral margin of telson armed with spines; apex armed with 2 or more pairs of spines distinctly longer than laterals (Fig. 5j, m, n) 14 14. Apex of telson armed with 8 or more long spines (Fig. 5m, n); inner uropods with 3 or less (rarely 4) spines near statocyst (Fig. 41, m) 15 Apex of telson armed with 6 or less long spines (Fig, 5j); inner uropods with 4 or more spines near statocyst (Fig. 4j) Mysidopsis bigelowi (Page 235) 15. Apex of telson with 12 to 16 long spines gradually increasing in length to the midline (Fig. 5n); inner uropod with 1 spine near statocyst (Fig. 4m) Mysidopsis almyra (Page 236) Apex of telson with 8 to 12 long spines abruptly increasing in length to the midline (Fig. 5m); inner uropod with 2 or more spines near statocyst (Fig. 41) Mysidopsis bahia (Page 236) ANCHIAL1NA TYPICA (KR0YER, 1861) Description Carapace Rectangular in appearance, anterior dorsal margin a broad rostral plate, the distal end appearing Hat and covering entire base of eyestalks. Posterior dorsal margin slightly concave, covering all thoracic segments (Figure 2a). Antennal peduncle and scale - Scale very small, about 1 .8 times as long as wide at its midlength, rhomboidal in appearance; lateral margin straight, devoid of setae, ending in minute tooth; apex and inner margin broadly rounded, bearing setae, distal tip with faint suture. Second segment of peduncle massive, about 3.5 times as long as third segment and 1.2 times as long as scale. Inner distal margin of sympod with long curved projection bearing barbs on inner margin, outer distal corner with small tooth (Figure 3a). Uropods — Exopods about 0.8 times as long as telson and slightly shorter than endopods; lateral margins usually bearing a row of about 18 spines, increasing in length to the larger inwardly curved distal spines, setae present along inner margin. Endopods slightly longer than telson, bearing patterned row of 45 to 50 spines of variable length, the distal 2 spines being longest, both inner and outer margins bearing setae (Figure 4a). Telson - Rather long, about 2.7 times maximum width; distal end with deep cleft bearing 30 to 40 slender laminae, increasing in length to apical lobes; lateral margins straight, distal one fourth curving slightly inward, proximal one fifth unarmed, remainder bearing 25 to 35 spines of variable length which tend to be more concentrated and longer distally; each apical lobe bearing 1 large straight spine (Figure 5a). Other characters — General appearance distinctly stout and robust. Integument covered with many minute hairs concentrated on dorsal surfaces of antennae, uropods and telson. First pair of pleopods in males unbamous, all others biranious. Third male pleopod with long 11-segmented exopod bearing modified setae. All pleopods of females reduced to uniramous plates. Length - Adult males to 5.8 mm and females to 5.0 mm. Ecology — Polyhaline, hypoplanktonic. BOWMANIELLA PORTORICENSIS BACESCU, 1968 Description Carapace — Anterior dorsal margin a long, slendei , acutely pointed rostrum descending somewhat between the eyes and reaching cornea. Posterior dorsal margin deeply concave. Key to Mysidacea of North Central Gulf of Mexico 229 Figure Antennal peduncle and scale: (a) Anchialina typtca, (b) Bowmaniella portoricensis, (c) Bowmaniella floridana, (d) Bowmaniella brasiliensts, (e) Pseudnmrm sp M (0 Amelia ihompsonii, (g) Promysis atlantica, (h) Metamysidopsis swifti, (i) Bathymysis renoculata, (j) Mysi- dopsis bigelowi, (k) Mysidopsis furca, (I) Mysidopsis bahia, (m) Mysidopsis almyra, (n) Brasilomysis ea&trol, (o) Heteromysis formosa, (p) Taphromysis louisianae, (q) Taphromysis bow man i. 230 STUCK ET AL. Figure 4. Uropod: (a) Anchiatina typica, (b) Bowmaniella portoricensis, (c) Bowmaniella brasiliemis, (d) Bowmaniella floridana, ( e)Pseu - domma sp., (f) Siriella thompsonii, (g) Pro my sis atlantica, (h) Meiamysidopsis swifti, (i) Bathymysls renoculata, (j) Mysldopsis blgelowi, (k) Mysidopsis furca, (!) Mysidopsis bahia, (m) Mysidopsis aimyra, (n) Brasitomysis castroi, (o) Heteromysis fortnosa, (p) Taphromysis louisianae, (q) Taphromysis bowmani, (r) Taphromysis bowmani, intermediate form. Key to Mysidacea of North Central Gulf of Mexico 231 0.5 = e,g,h,j 0.8 = a-d, f, i, k-o, q-s 1.4 = p Figure 5. Telson: (a) Anchialina typica, (b) Bowmanielb portoricensls, (c) Bowmaniella fioridana, (d) Bowmanfella brasiliensis, (e) Pseudornnw sp., (f) Siriella ihompsonii . (g) Promysis atlantica, (h) Meiamysidopsis swifti. (i) Boihymysls renoculata, (j) Mysidopsis bigelowi, (k) Mysi- dopsis furca, male, (I) Mysidopsis furca, female, (m) Mysidopsis bahia, (n) Mysidopsis almyra , (o) Brasiiomysis castroi , (p) Heteromysis formosa, (q) Tophromysis louisianae, (f) Taphromysls bowmani, (s) Taphromysis bowmani , intermediate form. 232 Stuck et al. bearing 2 oval-shaped lobes that form a slight sulcus, seventh and eighth thoracic segments exposed dorsally (Figure 2b). Antennal peduncle and scale - Scale about 3.2 times as long as wide at its midlength , faint suture separating distal tip of apex; lateral margin devoid of setae, ending in small distal tooth not extending beyond apex of scale; inner margin and apex setose. Third segment of peduncle about 0.4 times as long as second; entire peduncle about 1 .3 times as long as scale (Figure 3b). Uropods Exopods subequal in length with endopods bearing a row of 13 to 16 large spines on outer margin, inner margin setose. Inner margin of endopods bearing 3 or 4 large spines extending from area of statocyst to distal tip; row of 5 to 7 small spines extending distally from inner margin of statocyst; both inner and outer margins setose (Figure 4b). Telson — Cleft and rectangular in appearance, about 3.0 times as long as wide at its midlength ; lateral margins nearly straight, bearing 6 to 9 spines; each apical lobe with a pair of large spines. Terminal cleft relatively deep, about 0.14 times total length of telson, each inner margin bearing 14 to 17 spinules (Figure 5b). Other characters — Third pleopod of male bearing a large, complex copulatory organ on its distal end. All pleo- pods of females reduced to uniramous plates. Remarks The copulatory organ is similar to that of B. floridana in having a large striated lobe distally, but lacks the membranous accessory lobe. This species is easily distin- guished from B. brasiliensis by the lack of the hook-like terminal apophysis and the presence of a striated lobe distally. The illustrations and description presented here are in general agreement with the original description by Bacescu (1968) with some exceptions. BScescu reported the number of lateral spines on the telson to be 7 for females and 4 to 5 for males. Females examined by the authors from the northern Gulf of Mexico have 7 to 9 lateral spines on the telson, males 6 to 7. The depth of the terminal cleft was also slightly less in our specimens. Length -h Mature males to 9.0 mm and females to 1 1 .0 mm. Ecology - Hypoplanktonic, streamlined modified body adapted for burrowing in sand substrates. Polyhaline, not known from estuarine habitats. BOWMAN JELL A SPP. Reliable separation of B. floridana and B. brasiliensis is based on the structure of the distal complex of the male third pleopod. Females and immature males of these two species are, for all practical purposes, impossible to separate and are therefore treated together in the following description. Description Carapace - Anterior dorsal margin a long, slender, acutely pointed rostrum extending to cornea of eye. Posterior dorsal margin deeply concave, forming an M-shaped sinus with 1 small median and 2 larger lateral lobes, seventh and eighth thoracic segments exposed dorsally (Figure 2c, d). Antennal peduncle and scale — Scale about 3.5 times as long as wide al its midlength, faint suture separating distal tip of apex; lateral margin devoid of setae, ending in large distal tooth extending well beyond apex of scale; inner margin and apex setose. Third segment of peduncle about 0.3 times as long as second segment; entire peduncle equal to or slightly longer than scale (Figure 3c, d). Uropods — Exopod about 1.2 limes as long as endopod and bearing row of about 15 to 21 strong, evenly spaced spines along lateral margin; inner margin setose. Inner margin of endopod bearing 4 to 7 large spines qx tending from area of statocyst to distal tip; both inner and outer margins setose (Figure 4c, d). Telson - Cleft and rectangular in appearance, about 2.7 times as long as wide at its midlength; lateral margins nearly straight, bearing 6 to 8 spines; each apical lobe bearing 1 pair of large spines. Depth of cleft about 0.12 times entire length of telson, each inner margin with about 12 to 15 spinules (Figure 5c, d). Other characters - Posterior dorsal margin of fifth abdominal segment with articulated process (Figure 1) in both Bowrmniella floridana and B. brasiliensis, this process lacking in B. portoricensis. BOWMANIELLA ELORIDANA HOLMQUIST, 1975 Description Third pleopod of male — Copulatory organ large and complex. Terminal lobular complex composed of a large striated lobe and a smaller accessory lobe. Outer stylet slightly curved, smooth and pointed. Apical claw slightly curved, indented, bearing a row of curved spmes. Para- apical claw also curved, laminated and bearing many spines (Figure 6). Remarks - Brattegard (1970) included the northern Gulf of Mexico in the known range for B. dissimilis (Coif- mann, 1937). Holmquist (1975) stated that Brattegard 's illustrations are of specimens which do not belong to B. dissimilis, but to a new species, B. floridana. Examination of a large number of specimens of this type from the nor- thern Gulf of Mexico revealed agreement with Holmquist’s B. floridana (= B. dissimilis sensu Brattegard, 1970) with one exception. Brattegard stated, “bow absent" from male copulatory organ and Holmquist made no mention of such a bow. All specimens of B. floridana from the present study clearly possess a bow (Figure 6). Either Brattegard over- looked the bow or the specimens illustrated herein repre- sent a new species. These differences are currently under investigation by Thomas E. Bowman of the United States National Museum. Gastrosaccus dissimilis Coifmann, 1937, was originally described off the coast of Brazil between Pernambuco and Key to Mysidacea of north Central Gulf of Mexico 233 Rio de Janeiro. Brattegard (1970) considered Bowmaniella dissimilis conspecific with both Gastrosaccus dissimilis and Bowmaniella ( CoifmannieUa ) dissimilis sensu Bacescu, 1968. Tattersall (1951) reported G. dissimilis from the Louisiana Gulf coast; however, his illustration of the male third pleopod (fig. 29, p. 97) differs greatly from that of Coifmann ( 1 937) (fig. 3c, p. 7). While TattersalFs illust ration lacks detail, it is very similar to the male third pleopod of our specimens of B. floridana (Figure 6). No specimens of B. dissimilis were identified from our samples, suggesting that previous records for this species in the study area may be B. floridana. Bowman (personal communication) indicated that many published records of B. dissimilis are probably B. floridana : however, a reexamination of these specimens will be necessary to validate this assumption. Length - Adult males to 8.0 mm and females to 10.0 mm. Ecology - Hypoplanktonic, common in estuarine waters. BOWMANIELLA BRASILIENSIS BACESCU, 1968 Description Third pleopod of male - Copulatory organ smaller than that of B . floridana, lacking a large terminal lobular complex. Terminal apophysis descending from a hook-like seizing device. Inferior stylet developed into a long membranous lamina. Para-apical claw strongly curved upward, lower margin indented and bearing a row of slender spines. Apical claw long, slender and curving downward, bearing a few scattered spines (Figure 7). Remarks - Bacescu (1968) has referred to Coifmann’s (1937) illustration of the male third pleopod (Fig. 3c, p. 7) of Gastrosaccus dissimilis as being somewhat similar to his drawing (Fig. 6d, p. 366) of B. brasitiensis. Coifmann’s illustration clearly shows a slender apical claw which curves downward, an upward curving para-apical claw and a term- inal apophysis. These structures are also in general agree- ment with Q£ccscu*s detailed illustration (fig. 5b, p. 364) of the male copulatory organ; however, the identification of the para-apical and apical claw were apparently reversed. The taxonomic status of B. brasiliensis should be examined in light of these similarities. Bowmaniella brasiliensis is a fairly common species, often taken with B. floridana. The lack of published reports of this species from other Gulf states'suggests that it may have been included under the name B. dissimilis. Length — Adult males to 8.0mm and females to 10.0 mm. Ecology — Hypoplanktonic, common in estuarine waters. PSEUDOMMA SP. Description Carapace — Rectangular in appearance, lacking rostrum. Eyes fused, forming an ocular plate extending across anterior margin of carapace. Posterior dorsal margin strongly concave, exposing seventh and eighth thoracic segments (Figure 2e). Antennal peduncle and scale — Scale with setae along inner margin, outer margin lacking setae and terminating in large tooth. Third segment of peduncle about 1.2 times as long as second segment, extending two thirds of the distance along scale (Figure 3e). Uropods Exopods about 1.25 times as long as telson, subequal in length to endopods. Both endopods and exopods bearing setae along inner and outer margins, devoid of spines (Figure 4e). Telson - Linguifonn, entire, about 3.0 times as long as wide at its midlength; apex armed with 2 pairs of large spines, smaller pair laterally; lateral margins with 5 to 7 sharply pointed serrations (Figure 5e). 234 Stuck et al. Remarks - The species appears to be undescribed. Specimens do not key to any of the recognized species of Pseudomma (Bowman, personal communication). Descrip- tion awaits collection of male specimens. SIRIELLA THOMPSON I I (H. M1LNE-EDWARDS, 1837) Description Carapace — Anterior dorsal margin an acutely pointed rostral plate, partly covering the base and extending belween eyestalks. Posterior margin concave, loose, exposing eighth and part of seventh thoracic segments (Figure 2f). Antennal peduncle and scale — Scale about 5,5 times as long as wide at its midlength; lateral margin straight, devoid of setae, ending in tooth; apex rounded, extending past lateral tooth; inner margin and apex setose. Second segment of peduncle long and slender, about 4.0 times as long as third segment; entire peduncle about 0.8 times as long as scale (Figure 30- Uropods - Exopods about 1 .2 times as long as telson and slightly shorter than endopods; proximal three fourths of lateral margin devoid of setae and separated from distal one fourth by suture, a row of 3 to 6 graduated spines, increasing in length distally, located anterior to suture; outer margin of distal segment and entire inner margin setose. Endopod bearing row of about 70 spines of unequal size and irregular arrangement, extending from staloeyst to apex, which bears a single large spine; both inner and outer margins setose (Figure 4f). Telson ~ Slender, about 2.8 times as long as maximum width; distal end rectangular in appearance, armed with 3 pairs of long spines on corners, 3 much smaller spines and a pair of plumose setae medially; lateral margins nearly straight, except for slightly concave area along proximal one third; about 25 spines of variable size and spacing extend from about proximal one fifth to distal end (Figure 5f). Other characters - Endopods of thoracic limbs elongate, terminating in ‘'brush” of stiff setae. First pleopod of male with well-developed exopod and a bi-lobed(pseudobranchial) process, lacking a well-developed endopod. Pleopods 2 through 5 with both exopods and endopods well-developed and bearing colled, bi-lobed pseudobranchiae. All pleopods of females reduced to uniramous plates. Length - Adult males to 6.5 mm and females to 5.7 mm. Ecology — Polyhaline, planktonic. PROMYS/S ATLANTICA TATTERSALL, 1923 Description Carapace — Anterior dorsal margin a broad, bluntly pointed rostral plate which covers and extends past base of eyestalks. Posterior dorsal margin concave, exposing eighth and part of seventh thoracic segments (Figure 2g). Antenna! peduncle and scale — Scale about 8.0 times as long as wide at its midlength, bearing a few setae along both margins, lacking a lateral tooth; distal one fourth divided from remainder of scale by a suture. Third segment of peduncle about 0.7 times as long as second segment; entire peduncle about 0.8 times as long as scale (Figure 3g). Uropods - Exopods about 1.8 times as long as telson and slightly longer than endopods, setose along both margins. Endopods curving inward toward telson, inner margin bearing a row of about 24 spines of variable size and spacing extending from statocyst to distal tip; apex bearing 2 strong curved spines, much longer than others; both inner and outer margins setose (Figure 4g). Telson - About 1.8 times as long as maximum width, terminal notch devoid of setae or spines; lateral margins relatively straight, devoid of spines on proximal one fourth, distal three fourths armed with 18 to 23 spines of about equal size; each apical lobe with 2 spines, slightly longer than lateral spines (Figure 5g). Other characters — General body form slender, abdomen appears very elongate with sixth segment twice as long as fifth segment. Pleopods of males biramous, endopod of pleopod l rudimentary, exopod of pleopod 4 bearing a long barbed seta. All pleopods of females reduced to uni- ramous plates. Length — Adult males and females to 8.0 mm. Ecology - Polyhaline, planktonic, sometimes found in large aggregations. METAMYSIDOPSIS SWIFTl BACESCU, 1969 Description Carapace - Anterior dorsal margin a broadly triangular, bluntly pointed, rostral plate extending just beyond base of eyestalks. Posterior dorsal margin concave, exposing eighth thoracic segment (Figure 2h). Antennal peduncle and scale — Scale about 7.5 times as long as wide at its midlength, suture separating distal one fifth, setose along both margins, lacking lateral tooth. Third segment of peduncle about 0.8 times as long as second segment; entire peduncle shorter than scale (Figure 3h). Uropods - Exopod about 1.8 times as long as telson and 1 .4 times as long as endopod, outer margin slightly concave, setose along both margins. Inner margin of endopod bearing row of 14 to 21 spines of unequal size extending from area of statocyst distally along proximal two thirds; both inner and other margins setose (Figure 4h). Telson — Broadly linguiform with rounded apex; proximal two thirds devoid of spines* distal one third of each margin bearing 11 to 15 spines of about equal size and spacing lateral to a longer pair of midapical spines (Figure 5h). Other characters — All pleopods of males biramous, endopod of first pleopod rudimentary, exopod of fourth pleopod 6-segmented and bearing a long barbed seta off terminal segment. All pleopods of females reduced to uniramous plates. Key to Mysidacea of North Central Gulf of Mexico 235 Remarks - A certain confusion exists in the literature on the occurrence of several species of Metamysidopsis from northern Gulf waters. Tattersall (1951) reported Metamysidopsis munda (Zimmer, 1918) from Calcasieu Pass, Louisiana. Bacescu (1969) reviewed the genus Meta- mysidopsis and synonymized Tattersall's M. munda with M. mexicana Bacescu, 1969. An examination of Tattersall’s material from Calcasieu Pass, Louisiana, revealed specimens to be M . swift i and not M. munda or M. mexicana. Speci- mens identified as M. mexicana from Mullet Key, off Tampa, Florida, obtained from the U.S. National Museum, were also examined and found to be M. swifti\ however, the antennal scale and peduncle were of the size and propor- tions similar to M. mexicana . Of the hundreds of specimens examined from the northern Gulf, none have been identifi- able to either M. mexicana or M. munda. We therefore believe that neither M. mexicana nor M. munda has been reported reliably from the coastal waters of the northern Gulf. Length - Adult males to 4.8 mm and females to 5.5 mm. Ecology - Upper mesohaline, abundant in surf zone. BATHYMYSIS RENOCULATA TATTERSALL, 1951 Description Carapace Anterior dorsal margin a well-developed tri- angular rostral plate, apex pointed and extending well between eyes. Posterior dorsal margin concave, exposing eighth and part of seventh thoracic segments (Figure 2i). Antennal peduncle and scale — Scale about 7.5 times as long as wide at its midlength, with distal suture, setose along both margins, lacking lateral tooth. Third segment of peduncle about 0.6 times as long as second segment; entire peduncle slightly more than one half the length of scale (Figure 3i). Vropods — Exopods about 1 .6 times as long as telson and about 1.3 times as long as endopods, very slender in appearance, setose along both margins, Endopods about 1 .2 times as long as telson, bearing a row of about 33 equally spaced spines that gradually increase in length from area of statocyst to apex, both inner and outer margins setose (Figure 4i). Telson — About twice as long as maximum width, lateral margins armed with about 25 to 40 long spines, more concentrated along the distal margins; each apical lobe armed with 2 spines slightly longer than those along lateral margins. Terminal cleft deep, about one fifth of the total length of telson, bearing about 30 short spines proximally and 3 pairs oflarger spines distally (Figure 5i). Other characters — Pleopodsof males biramous, endopod of first pleopod rudimentary, exopod of fourth pleopod 8-segmented and about twice as long as endopod, distal margin of sixth and seventh segments of exopod each bear- ing a long plumose seta, eighth segment reduced and bearing 1 long and 1 short simple seta. Length - Adult males and females to 9.0 mm. Ecology — Polyhaline, hypoplanktonic. MYSIDOPSIS BIGELOW/ TATTERSALL, 1926 Description Carapace — Anterior dorsal margin a short, bluntly pointed rostral plate partly covering and extending slightly beyond base of eyestalks. Posterior dorsal margin slightly concave, loose, exposing eighth and part of seventh thoracic segments (Figure 2j). Antennal peduncle and scale — Scale about 6.5 times as long as wide at its midlength, bearing setae along both mar- gins, without lateral tooth or distal suture. Third segment of peduncle about 0.6 times as long as second segment; entire peduncle about 0.6 times as long as scale (Figure 3j). Vropods — Exopods about twice as long as telson and about 1.2 times as long as endopods, setose along both margins. A row of 4 or 5 graduated spines present along inner margin of endopod medial to statocyst, proximal spine being shortest and distal spine longest (Figure 4j). Telson - Broadly linguiform. without terminal cleft or emargination, length about 1.6 times maximum width; lateral margins slightly concave, bearing 10 to 13 short, stout, evenly spaced spines; apex rounded, bearing 3 pairs of widely spaced spines, the inner 2 pairs subequal in length and much longer than outer pair (Figure 5j). Other characters - Endopod of second thoracic limb greatly enlarged. Pleopods of males biramous, endopod of pleopod 1 rudimentary, exopod of pleopod 4 bearing a long barbed seta on the terminal seventh segment. All pleopods of females reduced to unirarnous plates. Remarks — Mysidopsis bigelowi is easily distinguished from the other species of Mysidopsis in the present key by the greatly enlarged endopod of the second thoracic limb. Length - Adult males and females to 7.0 mm. Ecology' - Polyhaline, hypoplanktonic, abundant in offshore waters. MYSIDOPSIS FURCA BOWMAN, 1957 Description Carapace - Anterior dorsal margin a bluntly triangular rostral plate extending only to base of eyestalks. Posterior dorsal margin loose, concave, exposing eighth and part of seventh thoracic segments (Figure 2k). Antennal peduncle and scale - Scale about 4.7 times as long as wide at its midlength, bearing setae along both mar- gins, without lateral tooth, faint suture present on distal tip. Third segment of peduncle about 0.6 times as long as second segment; entire peduncle about 0.6 times as long as scale (Figure 3k). Vropods - Exopodsabout 1 .2 times as long as endopods, slightly less than 1.5 times as long as telson in males, more than 1.5 times as long as telson in females. Endopods with 236 Stuck et al. row of 30 to 40 strong spines of variable length along inner margin extending from statocyst to near distal tip. Endopods and exopods bearing setae along both margins (Figure 4k). Telson — Showing sexual dimorphism. Female telson very distinctive, resembling a pitch fork; length about 1.2 times as long as maximum width; lateral margins concave, bearing 7 to 1 0 spines; apex armed with 2 pairs of long heavy spines, outer pair curved inward and inner pair almost straight (Figure 51). Male telson about 1,4 times as long as maximum width; lateral margins less concave than in females and bear- ing 10 to 12 spines; apex with 2 pairs of straight spines, outer pair about one-half length of inner pair (Figure 5k). Telson with slight emarginalion between the inner pair of spines in both males and females. Other characters — Pleopodsof males biramous, endopod of pleopod 1 rudimentary; endopod and exopod of fourth pleopod of males subequal in length, exopod 7-segmented, bearing a long barbed seta on distal tip. All pleopods of females reduced to uniramous plates. Remarks - Mysidopsis furca is easily distinguished from the other species of Mysidopsis in the present key by the armature and emargination of the distal end of the telson as well as by the large number and size of the spines on the endopods of the uropods. The female telson and uropods agree closely with the descriptions by Bowman (1957) but differ from those of Brattegard (1969), who apparently illustrated immature specimens. Length — Adult males and females to 6.0 mm. Ecology — Poly haline, hypoplanktonic. MYSIDOPSIS BAHIA MOLENOCK, 1969 Description Carapace ~ Anterior dorsal margin a broadly rounded rostral plate extending to base of eyestalks. Posterior dorsal margin loose, slightly concave, exposing eighth thoracic segment (Figure 21). Antennal peduncle and scale — Scale about 7.0 times as long as wide at its midlength, bearing setae along both margins, without distal suture or lateral tooth. Third segment of peduncle about 0.7 times as long as second segment; entire peduncle slightly less than one-half total length of scale (Figure 31). Uropods - F.xopod about 1 .8 times as long as telson and about 1.3 times as long as endopods, bearing setae along both margins. Endopod about 1.2 times as long as telson, bearing setae along each margin, with 2 or 3 (rarely 4) slender spines medial and slightly posterior to statocyst (Figure 41). Telson — Linguifonn, without terminal cleft or emargin- ation, length about 1 .7 times maximum width; lateral margins slightly concave, bearing 10 to 21 spines; apex broadly rounded, bearing 4 to 6 pairs of closely set spines abruptly increasing in length from lateral-most pair to medial pair (Figure 5m). Other characters - All pleopods of males biramous, endopod of pleopod 1 rudimentary, fourth pleopod bearing a long barbed seta on tip of 7-segmented exopod. Ail pleo- pods of females reduced to uniramous plates. Remarks - Many specimens of M. bahia examined from the northern Gulf displayed variable concentrations of heavy black pigmentation along the entire ventral margin in addi- tion to the normal ventral abdominal pigments character- istic of other species of Mysidopsis. Length - Adult males to 7.0 mm and females to 8.0 mm. Ecology — Estuarine, commonly occurring in salinities above 15.0 °/n o, rarely taken in salinitites as low as 2.0 °/oo, often collected with Af. almyra. MYSIDOPSIS ALMYRA BOWMAN, 1964 Description Carapace — Anterior dorsal margin a broadly rounded rostral plate, not produced between eyestalks. Posterior dorsal margin loose, concave, exposing eighth and part of seventh thoracic segments (Figure 2m). Antennal peduncle and scale — Scale about 7.0 times as long as wide at its midlength, bearing setae along both mar- gins, without distal suture or lateral tooth. Third segment of peduncle about 0.7 times as long as second segment; entire peduncle slightly less than one-half length of scale (Figure 3m). Uropods — F.xopods about 2.0 times as long as telson and 1 .3 times as long as endopods, bearing setae along both margins. F.ndopods about 1 .2 times as long as telson, bearing setae along both margins and 1 spine just posterior and medial to statocyst (Figure 4m). Telson — Linguiform, without terminal cleft or emargin- ation, length about 1.6 times maximum width; lateral mar- gins slightly concave, bearing 15 to 24 spines of variable size, but generally increasing in length distally ; apex rounded , bearing 6 to 8 pairs of spines gradually increasing in length from lateral-most pair to medial pair (Figure 5n). Other characters — Pleopodsof males biramous, endopod of pleopod 1 rudimentary, fourth pleopod bearing a long barbed seta on distal end of 7-segmented exopod. All pleo- pods of females reduced to uniramous plates. Remarks — This species superficially resemblesA/. bahia , therefore careful determination of the spination of the inner ramous of the uropod is necessary. Length - Adult males to 7.5 mm and females to 10.0 mm. Ecology - Dominant mysid in northern Gulf estuaries, common in mesohaline to near fresh conditions, found over a salinity range of 0.0 to 32.0 °/oo, an important food item for local juvenile demersal fishes. BRASILOMYSIS CASTROI BACESCU, 1968 Description Carapace - Anterior dorsal margin a large, triangular Key to Mysidacea of North Central Gulf of Mexico 237 bluntly pointed rostral plate extending well beyond eye- stalks. Posterior dorsal margin concave, loose, exposing eighth and part of seventh thoracic segments (Figure 2n). Antennal peduncle and scale — Scale very slender, about 1 5.0 times as long as wide at its midlength, suture separating distal one seventh, setose along both margins, lacking lateral tooth. Second segment of peduncle about 2.5 times as long as third segment; entire peduncle about 0.6 times as long as scale. Sympod with minute tooth on lateral margin (Figure 3n)- Uropods — Exopod about 1 .25 times as long as telson and 1.2 times as long as endopods, outer margin concave, both margins setose. Endopod with large statocyst, setose along both margins, lacking spines along inner margin (Figure 4n). Telson — Linguiform, very distinctive in appearance, without terminal notch; proximal one half of lateral margins armed with about 15 widely spaced spines becoming longer and more concentrated distally, distal one half armed with 40 to 60 (total both margins) closely set spatulate spines which are continuous around apex (Figure 5o), Other characters — Eighth thoiacic limb always directed backward, endopods well-developed with proximal two thirds of merus (longest segment) armed with 4 to 5 straight spines along outer margin and a row of 8 to 12 strong curved spines along inner, lower margin. First male pleopod uniramous, all others blramous, exopod of fourth pleopod with a long barbed seta extending from terminal segment. All pleopods of females reduced to uniramous plates. Entire body form very slender in appearance. Length — Adult males and females to 8.0 mm. Ecology — Upper mesohaline to polyhaline, hypoplanktonic. HETEROMYS1S FORMOSA S. I. SMITH, 1873 Description Carapace - Anterior dorsal margin broadly triangular, a bluntly pointed rostral plate covering base of eyestalks. Posterior dorsal margin deeply concave, exposing eighth and part of seventh thoracic segments (Figure 2o). Antennal peduncle and scale ~ Scale short, broadly rounded inner margii), about 2.6 times as long as wide at its midlength, setose along both margins, without suture or lateral tooth. Third segment of peduncle about 0.8 times as long as second segment; entire peduncle about equal in length to scale. Outer distal corner of sympod with a small tooth (Figure 3o). Uropods - Exopods broadly rounded, slightly longer than endopods and telson, setose along both margins. 'Endo- pods about equal in length to telson, bearing a rgw of 16 to 19 spines of equal size and spacing along inner margins, both inner and outer margins setose (Figure 4o). Telson - About 1.6 times as long as maximum width; lateral margins nearly straight, devoid of spines along proximal half, distal half bearing 10 to 18 spines of equal size and spacing; each apical lobe bearing 1 large spine. Terminal cleft deep and broad, containing a total of 16 to 30 laminae (Figure 5p). Other characters — Endopod of third thoracic limb (males and females) with carpus and propod us fused to form a long undivided segment armed with 3 pairs of strong spines on the inner distal margin. Pleopods of both males and females rudimentary. Ecology — Polyhaline, hypoplanktonic. T API l ROM Y SIS LOUISIANA E BANNER, 1953 Description Carapace - Rostral plate short and bluntly rounded, barely reaching base of eyestalks. Anterior margin of carapace with a small acute tooth just below level of eyestalk. Posterior dorsal margin slightly concave, loose, exposing eighth and part of seventh thoracic segments (Figure 2p). Antennal peduncle and scale — Scale about 5.0 times as long as wide at its midlength, bearing setae along both mar- gins, distal tip demarked by a faint suture, lacking lateral tooth. Third segment of peduncle about 0.7 times as long as second segment, distal margin reaching just beyond middle of scale (Figure 3p). Uropods - Exopods about twice as long as telson, bearing setae along both margins. Endopods about 0.8 times as long as exopods, setose along both margins and bearing 1 long spine just posterior to statocyst along medial margin (Figure 4p). Telson - Short, broad and distally emarginate; lateral margins slightly concave, bearing 10 to 12 spines along each side. Terminal emargination U-shaped, armed with 40 or more laminae along entire distal margin (Figure 5q). Other characters — First and second pleopods of males rudimentary; exopod of fourth pleopod 6-segmented , distal end bearing a terminal and subterminal seta forming a “pincer-like” structure; terminal seta spinous, tip acute. All pleopods of females reduced to uniramous plates. Remarks ~ The above diagnosis differs from the original description of T louisianae by Banner (1953) who did not report the presence of the spine near the statocyst. Length - Adult males and females to 9.0 mm. Ecology •— Estuarine, not collected in salinities above 2.0 °/oo, common in freshwater ditches. TAPHROMYSIS BOWMANI BACESCU, 1961 Description Carapace - Rostral plate short and bluntly rounded, barely reaching base of eyestalks. Anterior margin of cara- pace devoid of spines. Posterior margin of carapace concave, loose, exposing seventh and eighth thoracic segments (Figure 2q). 238 Stuck et al. Antennal peduncle and scale - Scale about 4.2 times as long as wide at its midlength, bearing setae along both mar- gins, distal tip demarked by a faint suture, devoid of lateral tooth. Third segment of peduncle about 0.7 times as long as second segment; entire peduncle about two thirds of scale (Figure 3q). Uropods — Exopods about 1.5 times as long as telson and slightly longer than endopods. Both endopods and exo- pods bearing setae along both margins. Endopods bearing 1 long spine located medial and posterior to statocyst (Figure 4q). Telson — Short, broad and distally emarginate; lateral margins bearing 8 to 10 spines on each side, distal one half straight. Terminal em a rgin at ion broadly V-shaped and armed with 30 or less laminae (spine-like projections) along entire distal margin (Figure 5r). Other characters - Plcopods 1 and 2 of males rudimen- tary; exopod of fourth pleopod 6-segmented, distal end bearing a terminal and subterminal seta forming a “pincer- like” structure; terminal seta of outer ramous bifid at its tip as opposed to acute in T. louisianae. All pleopods of females reduced to uniramous plates. Remarks — Many of the specimens from Mississippi show heavy pigmentation on the dorsal surface. Specimens of T. bowmani obtained from Destin, Florida, agree in all details with the original description by Bacescu (1961) and Brattegard (1970); however, material taken east of Mobile Bay showed considerable variation. The telson of T. bowmani from St. Louis Bay, Mississippi, (Figure 5s) closely resembles that of T. louisianae in having slightly concave lateral margins which bear 10 or more spines and a U-shaped emargination containing 30 to 36 laminae. The size and proportions of the antennal scale and peduncle also more closely resemble T. louisianae. These specimens lack the distinctive spine on the anterior carapace of T. louisianae and the mouthparts, thoracic limbs and male fourth pleo- pod are all clearly closer to T. bowmani. The spine on the inner margin of the endopod of the uiopod is of a size and position consistent with T. bowmani (Figure 4r), Specimens of both T. louisianae and this '‘intermediate” form of T. bowmani have occurred simultaneously in samples from Davis Bayou and St. Louis Bay, Mississippi, and Lake Pontchartrain, Louisiana. The senior author is currently investigating the possibility that this “intermediate” form represents a hybrid of the two species, or yet an unde- scribed third species of Taphromysis. Length - Adult malesto 8.5 mm and females to 9.0 mm. Ecology — Estuarine, found over a much wider range of salinity than the closely related species, T. louisianae. ACKNOWLEDGMENTS The authors wish to express their appreciation to Thomas E. Bowman of the National Museum of Natural History for his critical review of the manuscript, confirma- tion of identification of selected species and the loan of pertinent specimens from the Museum. Thanks are also due to Don Watson who inked all line drawings and to Adrian Lawler for his helpful criticisms and suggestions. For his support and encouragement we are grateful to Thomas Mcllwain. REFERENCES CITED Baccscu, M. 1961. Taphromysis bowmani. n. sp., a new brackish water mysid from Florida. Bull. Mar. Sci. Gulf Caribb. 11(4): 517 524. . 1968. Contributions to Die knowledge of the Gastro- saccinae psammbionte of the tropical America, with the descrip- tion of a new genus ( Bowmaniclla , n.g.) and three new species of its frame. Trav. Mus. Hist. Nat. ‘Grigore Aniipa' 8:355 -373, . 1969. Contributions a la connaissance du genre Metamy- sidopsis W. Tattersall 1951, M. swifti n. sp. - M. mexicana n. n, confondues avec M. munda Zimmer. Rev. Roum. Biol. SerZool. 14 (5): 349 -357. Banner, A. H, 1953. On a new genus and species of mysid from southern Louisiana. Tulane Stud. Zool. 1(1 ):3 -8. Bowman, T. E. 1957. A new species of Mysidopsis (Crustacea: Mysidaoea) from the southeastern coast of the United States. Proe . U.S. Nall. Mus. 107(3378):1 -7. Brattegard, T. 1 969. Marine biological investigations in the Bahamas. 10. Mysidacea from shallow water in the Bahamas and southern Florida. Part 1. Sarsia 39:17-106. . 1970. Marine biological investigations in the Bahamas. 1 1 Mysidacea from shallow water in the Bahamas and southern Florida. Part 2. Sarsia 41:1 -35. Coifmann, I. 1937. Misidacei raccolti dalla R. corvetla Vettor Pisani negli anni 1882-85- Ann. Mus. Zool, Univ. Napoli, new ser. 7(3):1-14, Holmquisf ,C.l 975. Arevision of the species Archaeomysis grebnitzkii Czcrnaivsky and .4. maculata (Holmes) (Crustacea, Mysidacea). Zoot. Jb.Syst. Bd. 102:51 71, Smith, R. I. 1964. Keys to Marine Invertebrates of the Woods Hole Region. SystematicsrF.cology Program, Contribution No. 11, Marine Biological Laboratory, Woods Hole, Massachusetts. 208 pp. Tattersall, W. M. 1951. A review of the Mysidacea of the United States National Museum. U.S. Nall. Mus. Bull. 201 :1 —292. Gulf Research Reports Volume 6 | Issue 3 January 1979 Records and Range Extensions of Mycidacea from Coastal and Shelf Waters of the Eastern Gulf of Mexico Kenneth C. Stuck Gulf Coast Research Laboratory Harriet M. Perry Gulf Coast Research Laboratory Richard W Heard Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.04 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Stuck, K. C., H. M. Perry and R. W. Heard. 1979. Records and Range Extensions of Mycidacea from Coastal and Shelf Waters of the Eastern Gulf of Mexico. Gulf Research Reports 6 (3): 239-248. Retrieved from http:// aquila.usm.edu/gcr /vol6/iss3/4 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua. Cromwell(2)usm.edu. Gulf Research Reports, Vol. 6, No. 3, 239-248, 1979. RECORDS AND RANGE EXTENSIONS OF MYSIDACEA FROM COASTAL AND SHELF WATERS OF THE EASTERN GULF OF MEXICO KENNETH C. STUCK, HARRIET M. PERRY AND RICHARD W. HEARD Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ABSTRACT Records of seventeen species of My sidacca from the Gulf of Mexico are presented . Bowmaniella portoricensis, Pseudomma sp., Siriella thompsonii and Bathymysis renoculata are recorded from the Gulf for the first time. Range exten- sions within the Gulf are established for Anchialina typica and Mysidopsis furca. Records of Brasilomysis castroi and Mysidopsis almyra from the Atlantic coast of the United States are reported . INTRODUCTION The offshore benthic and planktonic mysidacean fauna of the Gulf of Mexico are poorly known; however, the shallow-water species have been investigated by several authors. Brattegard (1969, 1970) reported eight species from coastal waters off southern Florida and presented their taxonomic characters. Farrell (1979) provided a key to 24 nearshore species from Florida but did not Include data on collection sites, The Mysidacea of the western Gulf of Mexico have been studied by Price, who identified seven species from Galveston Bay, Texas (1976), and four species from Mexico (1975, 1978). The taxonomic works of Banner (1953), Clarke (1956), Bacescu (1961, 1969), Bowman (1964) and Molenock (1969) have also added to the knowl- edge of the group in the Gulf of Mexico. Ecological studies and baseline inventories in northern Gulf estuaries have contributed data on a limited number of species (cited in text). Records of some Mysidacea from the Gulf of Mexico appear to be in error, due in part to confusion in the literature (Stuck et al. 1979). In addition to establishing new records and range extensions for Gulf mysids, data are presented here to clarify the known distribution of several shallow- water species. MATERIALS AND METHODS This report is based on a collection of mysid shrimps of the family Mysidae from the continental shelf waters off Mississippi, Alabama, and Florida, and supplemented with material from shallow, estuarine waters in the northeastern Gulf of Mexico. Specimens were provided to the authors from the following sources: 1 . National Marine Fisheries Service under Public Law 88-309, Project 2-42-R. 2. National Marine Fisheries Service under Public Law 88-309, Project 2-215-R. 3. Dames and Moore under Contract N. AA550— CT7- Manuscript received September?, 1979; accepted October 3, 1979. 34 from the Bureau of Land Management. 4. Steve Heath, Alabama Marine Resources Labora- tory; specimens from Dauphin Island and Gulf Shores, Alabama. 5. Shiao Wang, Gulf Coast Research Laboratory; specimens from continental shelf waters off Main Pass, Mississippi River. 6. Steve Manning, Gulf Coast Research Laboratory; specimens from Gulf Breeze, Florida. 7. Thomas E. Bowman, United States National Museum ; specimens from Mullet Key, Florida, and Calcasieu Pass, Louisiana. 8. The personal collections of Kenneth C. Stuck (KCS) and Richard W. Heard (RWH). Records of occurrence follow the style of Brattegard (1969, 1970). Plankton stations arc designated as either day (D) or night (N) and are followed by ihe depth of tow (S surface, M— midwater, B— bottom). Selected synonymies of interest to regional investigators are provided for each species when applicable. The study area, divided into four subareas based on geographic location, and collecting sites arc shown in Figures 1 through 5. Specimens were taken with a variety of gear types and these are included with station location and bottom type in the collecting sites listing. Sediment analysis was not available for many locations. A representative collection of the mysids reported herein has been deposited in the museum at the Gulf Coast Research Laboratory, Ocean Springs. Mississippi. COLLECTING SITES 1. Timbalier Bay, Louisiana; mud; Renfro beam trawl. 2. Terrebonne Parish, Louisiana; Gulf surf, sand; Renfro beam trawl. 3. Forty-two miles east of Main Pass, Mississippi River, 88°30'N, 29°25'W; plankton net. 4. Mouth of Bayou St. John, Orleans Parish, Louisiana; sand; Renfro beam trawl. 5. South shore of Lake Pontchartrain, Louisiana; sand, grass bed ; Renfro beam trawl . 239 240 Stuck et al. 6. North shore of Lake Pontcharlrain, Louisiana; sand, grass bed; Renfro beam trawl. 7. Cedar Point, St. Louis Bay, Mississippi; silty sand; Renfro beam trawl. 8. Henderson Point, Pass Christian, Mississippi; sand; Renfro beam trawl. 9. Gulfport Beach, Gulfport, Mississippi; sand; Renfro beam trawl. 10. East end of Deer Island, Mississippi; mud; Renfro beam trawl. 11. Fort Point, Biloxi Bay, Mississippi; sand, grass bed; Renfro beam trawl. 12. Davis Bayou, Mississippi; mud; Renfro beam trawl. 13. Belle Fontaine Beach, Mississippi; silty sand; Renfro beam trawl. 14. Cat Island Pass, Mississippi; Clarke-Bumpus plankton sampler. 15. Ship Island Pass, Mississippi; Clarke-Bumpus plankton sampler. 16. Ship Island; Gulf surf, sand; Renfro beam trawl. 17. Continental shelf,north central Gulf ofMcxico, 30°02'30" N, 88°40'15" W; plankton net. 18. Continental shelf,north centralGulf of Mexico, 29°42'00" N, 88°27'30" W; plankton net. 19. Continental shelf, north central Gulf of Mexico, 29°24'l5” N, 88°17'00" W; plankton net. 20. Continental shelf, north centralGulf of Mexico, 20°19'00" N, 88°14'00" W; plankton net. 21. Continental shelf, north central Gulf of Mexico, 29°17'1 5" N, 88°12'05" W; plankton net. 22. Dog Keys Pass, Mississippi; Clarke-Bumpus plankton sampler. 23. Chimney Lagoon, Horn Island, Mississippi; silty sand; Renfro beam trawl. 24. Middle Ground, Mississippi Sound; sand, grass bed; Re fro beam trawl. 25. Horn Island Pass, Mississippi; Clarke-Bumpus plankton sampler. 26. Dauphin Island, Alabama; gear type unknown. 27 . Gulf Shores, Alabama ; gear type unknown. 28. Gulf Breeze, Florida; sand; Renfro beam trawl. 29. Brackish water pond, Destin, Florida; sand; fine-mesh dip net. 30. Continental shelf, north central Gulf of Mexico, 29°43'29" N, 87°54'30" W; box core. 31. Continental shelf, NE Gulf of Mexico, 29°47'59" N, 86°09'29" W; box core. 32. Continental shelf, NE Gulf of Mexico, 28°23'59" N, 85°15'03"W;box core. 33. Continental shelf, NE Gulf of Mexico, 27°57'00" N, 84°47 , 59" W; box core. 34. Continental shelf, NE Gulf of Mexico, 29°47'00" N, 84°05'00" W, box core. 35. Continental shelf, NE Gulf of Mexico, 29°05'0l” N, 83°45'0l"W;box core. 36. Continental shelf, NE Gulf of Mexico, 28°30'00" N, 83 0 29'58” W; box core. 37. Continental shelf, NE Gulf of Mexico, 27°57'00" N, 83°09'00"W;box core. 38. Continental shelf, NE Gulf of Mexico, 27°56'0l" N, 83°27'30" W ; hox core. 39. Continental shelf, NE Gulf of Mexico, 27°52'3 1 " N, 83°33'59" W; box core. 40. Continental shelf, NE Gulf of Mexico, 27°57'29" N, 83°42'29" W;box core. 41. Continental shelf, NE Gulf of Mexico, 27°56'30" N, 83°53'00” W;box core. 42. Continental shelf, NE Gulf of Mexico, 27°37.2' N, 83°53.5' W; box core. 43. Continental shelf, NE Gulf of Mexico, 27°24.2' N, 84°07.3' W;box core. 44. Continental shelf, SE Gulf of Mexico, 27°03'26" N, 83°0l'09"W;box core. 45. Continental shelf, SE Gulf of Mexico, 26°25'00" N, 82°15'09" W;box core. 46. Continental shelf, SE Gulf of Mexico, 26°25'00" N, 82°58'00"W;box core. 47. Continental shelf, SE Gulf of Mexico, 26°25'00" N, 83°23'0l” W; box core. 48. Continental shelf, SE Gulf of Mexico, 25°40.0' N, 82° 20.0' W; box core. Gulf Records and Range Extensions of Mysidacea 241 Figure 2. Location of stations in subarea I. Figure 4. Location of stations in subarea III. Mississippi i Alabama 243 Depth contours in meters 244 Stuck et al. SPECIES ACCOUNT Anchialirta typica (Krtfyer) Arichialus typicus Kryiyer, 1861, p. 53, pi. 2, fig. 7a 1 Anchialina typica: Hansen, 19 10, p. 52, pi. 7, fig. 2a- k Anchialina typica: li, 1964, p. 188, figs. 48-49 Anchialina typica: Brattegard, 1970, p. 24, fig. 6 Anchialina typica: Stuck, Perry and Heard, 1979, p. 227, figs. 2a, 3a, 4a, 5a Occurrence — Station 19NM(males— 4, females— 1, ovig- erous females-0, juveniles— 0), 20NM(1 -3-1—0), 21NM (0-0— 1—0), 31(1 -0-0-0), 34(0-1 -0-0), 35(1-0-0 0), 3 7(1 -0-0-0), 42(0 - 1 0-0), 4 5(0 - 1 -0-0), 48(0-0- 0- 1). Gulf of Mexico Records — Hopkins ( 1 966). Distribution - Widely distributed in the tropical and sub- tropical regions of the Atlantic and Pacific oceans (li 1964). Reported from waters off Nova Scotia (Nouvel 1943), the continental shelf off South Carolina (Wigley and Burns 1971), Biscayne Bay, Florida (Brattegard 1970). St. Andrew Bay, Florida (Hopkins 1966), and the continental shelf waters off Mississippi (present study). Bowmaniella portoricensis Bacescu Bowmaniella portoricensis Bacescu, 1968, p. 357, figs. la— n, 2a -e, 3 a— b Bowmaniella portoricensis: Stuck, Perry and Heard, 1979, p.227, figs. 2b, 3b, 4b, 5b Occurrence — Station 19DB(males— 1 , females— 21, ovig- erous females-0, juveniles 0), 20NM(0— 0-0-2), 30(0-1 — 0-0), 35(0-1-0-0), 37(0— 1 -0-0), 38( l -4—0— 1 ), 39( 1 — 0-0-0), 40(1-1-0-0), 46(0-1-0-0), 47(0 4-0-0), 48(0-1-0-0). Gulf of Mexico Records ^Previously unreported. Distribution - Cape Hatteras, North Carolina, to Fort Pierce, Florida (Wigley and Burns 1971), and continental shelf waters off Mississippi (present study). Bowmaniella floridana Holmquist Gastrosaccus dissimilis Tattersall, 1951 (in part), p. 97, fig. 29 Bowmaniella dissimilis: Brattegard, 1970, p. 1 1, fig. 2 Bowmaniella floridana Holmquist, 1975, p. 68 Bowmaniella floridana: Stuck, Perry and Heard, I979,p. 232, figs. 2c, 3c, 4d, 5c Occurrence - Mature males only, station 12(4), 13(6), 24(4). Gulf of Mexico Records - Tattersall (1951), Hopkins (1966), Bacescu (1968a), Brattegard (1970), Solomon (1970), Mackin (1971), Odum and Heald (1972), Williams (1972), Christmas and Langley (1973), Livingston et al. (1977), Cooley (1978). Distribution — In question. Remarks The taxonomic status of B, floridana is cur- rently being reviewed by Thomas E. Bowman of the United States National Museum. Stuck et al. (1979) have discussed the taxonomic problems associated with B. floridana, B. dissimilis and B. brasiliensis. Bowmaniella brasiliensis Bacescu Bowmaniella brasiliensis Bacescu, 1968a, p. 363, figs. 5a— d, 6 Bowmaniella brasiliensis: Stuck, Perry and Heard, 1979, p. 233, figs. 2d, 3d, 4c, 5d Occurrence - Mature males only, station 12(4), 13(6), 24(3), 26(2). Gulf of Mexico Records - Conte and Parker (1971), Mackin (1971), Price (1976, 1978). Distribution — Georgia (Brattegard 1974) to Brazil (Bacescu 1968a), Remarks - See Stuck et al. (1979). Pseudo mma sp. Occurrence - Station 20NM(females-2, juveniles— 2). Gulf of Mexico Records - Genus previously unreported. Remarks — This appears to be an undescribed species of Pseudomma, however, description awaits the collection of male specimens. Siriella thompsonii (H. Milne-Ed wards) Cynthia thompsonii H. Milne-Edwards, 1837, p. 462 Siriella thompsoni: Sars, 1885, p. 205, pi. 36, figs. 1-24 Siriella thompsoni: li, 1964, p. 62, figs. I4a-h, ISa-n Siriella thompsonii: Stuck, Perry and Heard, 1979, p. 234, figs. 2f, 3f, 4f, 5f Occurrence — Station 17DM(males— 1 , females— 1 1 , ovig- erous females— 2, juveniles— 0), 17NM(6— 28— 0— 3), 19DS (2— 7— 0-1), I9DB(2-0— 1-0), 20NS( 13-36-0-0), 21NS (2-4-1 -0). Gulf of Mexico Records - Previously unreported. Distribution — Oceanic with wide distribution in the tropical and temperate waters of the world (li 1964). Reported from the Straits of Florida (Tattersall 1926), and the continental shelf waters off Mississippi (present study). Promysis atlantica W. M, Tattersall Promysis atlantica W. M. Tattersall, 1923, p. 286, pi. 1, figs. 5 -6 Promysis atlantica: Tattersall, 1951, p. 245, fig. 56 Promysis atlantica: Clarke, 1956, p. 1, figs. 1—6 Promysis atlantica: Stuck, Perry and Heard, 1979, p. 234, figs. 2g, 3g, 4g, 5g Occurrence Station 3DS(males— 2, females— 7, ovig- erous females-0, juveniles— 1), 15DB(0-4-0-l), 17NM (2-14—2- 6), 1 8N M(0— 2— 2 —0) , 18NS(2-0-0- 0), 18NB (0-1— 0-0), 19DM(0-3 -0— 0), 19NS(0-l-0 l), 20NS (2— 4— 0—0), 21DB(6— 9— 1-0), 25DB(3-3-0-9). Gulf Records and Range Extensions of Mysidacea 245 Gulf of Mexico Records — Clarke (1 956),Hopkins(1966), Price (1976). Distribution - Brazil north throughout the Caribbean Sea, Gulf of Mexico and Atlantic coast of North America to just north of Cape Hatteras, North Carolina (Brattegard 1973). Metamysidopsis swifti Bacescu Metamysidopsis munda: Tattersall, 1951 (in part),p. 147 Metamysidopsis munda: Hopkins, 1966, p. 47 Metamysidopsis swifti Bacescu, 1969, p. 350, fig. 1 Metamysidopsis swifti: Brattegard, 1970, p. 30, fig. 8 Metamysidopsis swifti: Stuck, Perry and Heard, 1979, p. 234, figs' 2h, 3h, 4h, 5h Occurrence - Station 2(males-0, females— 0, ovigerous females—2, juveniles— 0), 13(0-4-0-0), 16(23-15-10-0), 26(0— l —0—0), Gulf of Mexico Records - Bacescu (1969), Brattegard (1970), Price (1975, 1976). Distribution - Mullet Key, Florida to Caribbean coast of Colombia (Brattegard 1973). Remarks - Metamysidopsis munda was reported from Calcasieu Pass, Louisiana, by Tattersall (1951); however, an examination of these specimens revealed them to be AL swifti . Specimens identified as M. mexicana from Mullet Key, off Tampa, Florida, were provided to the authors by Thomas E. Bowman of the United States National Museum. These specimens were also found to be M. swifti , thus adding the eastern Gulf of Mexico to its known range. Bathymysis renoculata W. M. Tattersall Bathymysis renoculata W. M. Tattersall, 1951, p. 153, figs. 57-58 Bathymysis renoculata: Stuck, Perry and Heard, 1979, p. 235, figs. 2i, 3i, 4i, 5i Occurrence - Station 18NM(males— 0, females— 1, ovig- erous females— 0, juveniles-0), 20NM(1 -0—0—1), 21NB (0—0— 0—2), 32(0-1 -0-0). Gulf of Mexico Records - Previously unreported. Distribution — Atlantic coast of the United States from New England to the southern tip of Florida (Tattersall 1951) and the north central Gulf of Mexico (present study). Remarks - This species was previously known only from the deeper waters of the western Atlantic Ocean at depths from 220 to 483 meters. It was identified in the present study from continental shelf waters off western Florida at depths of 180 meters. The records from the shelf waters off Mississippi were at much shallower depths, ranging from 37 to 91 meters. Mysidopsis bigelowi W, M. Tattersall Mysidopsis bigelowi W. M. Tattersall, 1926, p. 10, pi. 1, figs. 1-8 Mysidopsis bigelowi : Tattersall, 195 1 , p. 1 39, fig. 50 Mysidopsis bigelowi: Brattegard, 1969, p. 53, fig. 15 Mysidopsis bigelowi: Stuck, Perry and Heard, 1979, p. 235, figs. 2j, 3j, 4j, 5j Occurrence - Station 14DB(males-Q, females— 1, ovig- erous females-0, juveniles-8), 17NS(6-1 1-1-0), J7NM (7- 7— 3—0), 1 7NB(5— 8— 7— 1), 18NS(4-3-0-5), 18NM (8-6-1-0), 19NB(0— 3-2— 0), 20NS(1 -0-0-1), 20NM (4— 7— 0—0), 20DM(1 -3-0-0), 21DB(0-l-0-0), 22DB (3—1 — 1—1), 25DB(7— 2— 2— 1 2). Gulf of Mexico Records -Tattersall (195 1), Clarke (1 956), Brattegard (1969), Solomon (1970), Mackin (1971), Price (1976), Livingston et al. (1977), Sheridan (1978). Distribution - Aransas Bay, Texas (Solomon 1970), to Georges Bank (Wigley and Burns 1971). Mysidopsis furca Bowman Mysidopsis furca Bowman, 1957, p. 1 , figs. 12 Mysidopsis furca: Brattegard, 1969, p. 47, fig. 13 Mysidopsis furca : Stuck, Perry and Heard, 1979, p. 235, figs. 2k, 3k, 4k, 5k— L Occurrence — Station 17NM(maIes-0, females ! , ovig- erous females— 1, juveniles— 0), 18NM(0— 3-0-0), 18NB (1-1-1 -0), 34( 1 —2—0—0), 44(0- 1 -0-0), 45(2-0-0-0). Gulf of Mexico Records — Brattegard (1969). Distribution ~ North Inlet, South Carolina (Bowman 1957), to Pigeon Key, Florida (Brattegard 1969), and con- tinental shelf waters off Mississippi (present study). Mysidopsis bahia Molenock Mysidopsis bahia Molenock, 1969, p. 113, figs. 1 — 18 Mysidopsis bahia: Brattegard, 1970, p. 28, fig. 7 Mysidopsis bahia: Stuck, Perry and Heard, 1979, p. 236, figs. 21 , 31, 41, 5m Occurrence — Station l(males—l , females— 0, ovigerous females-0, juveniles-0), 2(0- 1-1-0), 6(0- 1-0-0), 7(0 1-0-1), 10(1-1-2-0), 12(0-0-1-0), 23(6-6-9—0), 24(0-2-12-0), 27(8-6-7-1). Gulf of Mexico Records — Molenock (1969), Brattegard (1970), Conte and Parker (1971), Mackin (1971), Odum and Heald (1972), Price (1976, 1978), Livingston et al. (1977), Sheridan (1978, 1979). Distribution - Laguna de Tamiahua, Mexico (Price 1978), to Buttonwood Channel, Cape Sable, Florida (Brattegard 1970). Mysidopsis almyra Bowman Mysidopsis almyra Bowman, 1964, p. 15, figs. 1-24 Mysidopsis almyra : Brattegard, 1969, p. 50, fig. 14 Mysidopsis almyra: Stuck, Perry and Heard, 1979, p. 236, Figs. 2m, 3m, 4m, 5n Occurrence — Station 1 (males— 14, females— 13, ovig- erous females— 9, juveniles 10), 2(4— 6-0-0), 4(13—12— 1-7), 5(90-22-41-2), 6(28-25-22-1), 7(7-7-19-0), 246 STUCK ET AL. 8(2-11-11-2), 9(0-3-14-0), 10(15-5-9-0), 11(32- 37-24-0), 12(24-25-69-0), 13(51-45-49-0), 15DB (1 1-0-4), 23(1-2-0-0), 24(7-3-4-0), 26(0-1-0-0), 27(10-5-3-2). Gulf of Mexico Records — Bowman (1964), Hopkins (1966), Brattegard (1969), Conte and Parker (1 97 i), Mackin (1971), Kalke (1972), Schmidt (1972), Odum and Heald (1972), Williams (1972), Christmas and Langley (1973), Subrahmanyam et al. (1976), Price (1976, 1978), Adkins and Bowman (1976), Tarver and Savoie (1976), Livingston et al. (1977),DesseUe et al. (1978), Gillespie (1978), Cooley (1978), Sheridan (1978). Distribution - Laguna deTamiahua, Mexico (Price 1978), to St. Johns River, Florida (Price and Vodopich 1979), and Ormond Beach, Florida (personal collection of RWH). Brasilomysis castroi Bacescu Brasilomysis castroi Bacescu, 1968b, p. 81, figs. 3—4 Brasilomysis castroi: Brattegard, 1969, p. 61, Fig. 1 8 Brasilomysis castroi: Stuck, Perry and Heard, 1979, p. 236, figs. 2n, 3n, 4n, 5o Occurrence — Station 1 5DB(males-0, feinales-0, ovig- erous females-0, juveniles-1), 17NM(1 -0-0-0), 18NS (1-1-0-0). 1 8NM(0— 2— 0— 0), 22DB(0— 1-0— 1), 25DB ( 0 — 2 — 0 — 2 ). Gulf of Mexico Records - Brattegard (1969), Conte and Parker (1971), Mackin (1971), Price (1976). Distribution - Brazil (Bacescu 1968b) to coast of Georgia (Brattegard 1974), and St. Catherine’s Sound, Georgia (personal collection of RWH). Heteromysis formosa S. I. Smith Hetcromysis formosa S. I. Smith, 1873, p. 553 Heteromysis formosa : Tattersall, 195 l,p. 235, figs. 100, 101 Heteromysis formosa: Brattegard, 1969, p. 92, fig. 29 Heteromysis formosa: Stuck, Perry and Heard, 1979, p. 237, figs. 2o, 3o, 4o, 5p Occurrence - Station 41(1 female). Gulf of Mexico Records — Tattersall (1951). Distribution - Western Atlantic from New England to the eastern Gulf of Mexico; eastern Atlantic Ocean, Norway, British Isles, France; Mediterranean off Monaco (Brattegard 1969). Remarks - One of the authors (KCS) examined a 1 2.0- mm specimen (female) from continental shelf waters east of the mouth of Main Pass, Mississippi River. Taphromysis louisiartae Banner Taphromysis louisianae Banner, 1953, p. 3, figs. 1—2 Taphromysis louisianae: Stuck, Perry and Heard, 1979, p. 237, figs. 2p, 3p, 4p, 5q Occurrence - Station 7(males-4, females-2, ovigerous females-0, juveniles-0). Gulf of Mexico Records — Banner (1953), Conte and Parker (1971), Mackin (1971), Conte (1972), Kalke (1972), Cali (1972), Harrel et al. (1976), Livingston et al. (1977). Distribution - Lavaca River, Texas (Mackin 1971), to Apalachicola Bay, Florida (Livingston et al. 1977). Taphromysis bowmani Bacescu Taphromysis bowmani Bacescu, 1961 , p. 5 17, figs. 1—2 Taphromysis bowmani: Brattegard, 1969, p. 89, fig. 28 Taphromysis bowmani: Stuck, Perry and Heard, 1979, p. 237, figs. 2q, 3q, 4q-r, 5r— s Occurrence — Station 6(males— 1, females-6, ovigerous females— 0, juveniles— 0), 7(1 — 1—0—15), 28(3-7—4-0), 29(3-2-0-0). Gulf of Mexico Records - Hopkins (1966), Brattegard (1969), Odum and Heald (1972), Subrahmanyam et al. (1976), Beck (1977), Livingston et al. (1 977), Bowman (1977), Cooley (1978), Sheridan (1978, 1979), Compton and Price (1979). Distribution - tipper Laguna Madre (Compton and Price 1979), to Biscayne Bay, Florida (Bacescu 1961). ACKNO WLEDGM ENTS The authors thank Thomas E. Bowman of the United States National Museum for confirming the identification of critical material. We acknowledge Don Watson and Beryl Heard for their assistance in the preparation of illustrations. Appreciation is extended to A. G. Fish of the University of Southern Mississippi for providing the incentive to undertake this study. REFERENCES CITED Adkins, G. & P. Bowman. 1976. A study of the fauna in dredged of its frame. Trav. Mus. Hist, nat . ‘Grigore Antipa’ 8:355-373. canals of coastal Louisiana. La. Wild!. Fish. Comm., Tech. Bull. _____ • 1968b. A fro my sis gv wen sis n.sp. and Brasilomysis 18:1-72. castroi n.g. n.sp. from the waters of the tropical Atlantic. Rev. Bacescu, M. 1961. 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Texas A&M University. 260 pp. Gulf Research Reports Volume 6 | Issue 3 January 1979 Studies of the Southern Oyster Borer, Thais haemastoma Gordon Gunter Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.05 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Gunter, G. 1979. Studies of the Southern Oyster Borer, Thais haemastoma. Gulf Research Reports 6 (3): 249-260. Retrieved from http://aquila.usm.edu/gcr/vol6/iss3/5 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(S>usm.edu. Gulf Research Reports, Vol. 6, No. 3, 249-260, 1979. STUDIES OF THE SOUTHERN OYSTER BORER, THAIS HAEM A STOMA GORDON GUNTER Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ABSTRACT Original work was carried on at the U.S. Bureau of Fisheries Laboratory on Apalachicola Bay from August 1935 to April 1936. Since then observations have been made in Texas, Louisiana and Mississippi. Five papers on specific aspects of the biology of the animal have been written since on this and other predatory gastropods. Here all commentaries are drawn together and unpublished matter is presented. The name Thais haemasioma is used because separations based upon the rugosity of the shells do not hold up. Perfectly smooth and very rugose specimens are found in the same bays, with various shell characteristics being related to various oyster reefs on which they grow. Radular movement is by the band-over-pulley method suggested by Husley (1853), Herrick (1906) Gunter (1936) and Carrikcr (1943). Evidence is presented showing that Thais can kill oysters without mechanical injury, presumbly by some paralytic material. About one-third of the oysters are opened by large Thais without any boring whatsoever. Smaller Thais are more prone to bore complete holes into the shell cavity of the prey. In Apalachicola Bay large Thais may eat one oyster about every 8 days and it was calculated that on St. Vincent's Bar 24 million adult oysters could be killed in a year. The resting gonads consist of a thin layer of tissue on the body over the liver and they are Javender^rey in the males and yellowish -orange in the females. They begin to thicken in January and the color intensifies. Egg laying takes place from April to July on the Gulf coast. No young or small Thais were seen in Apalachicola Bay probably because of heavy fresh- water drainage in the springs of 1934 and 1935. Several hundred Thais were measured and each mouth the length frequency mode was at 80.0 mm. The largest known specimen of Thais, a Louisiana specimen, was 103 mm long. A heavy kill of Thais took place in the spring of 1935 and no adults survived in Apalachicola Bay except on Hiles’ Bar near Indian Pass, which is close to the ocean. The Thais seemed to perish when salinity dropped to 9 /oo and stayed that way for several weeks. Both oysters and mussels survived at salinities lower than Thais could withstand. Thais shells are extremely hard and are difficult to break with a hammer. Nevertheless, they are cracked by stone crabs. They are also invaded by commensals such as the boring clam Diplothyra smithii, the annelid worm Poly dor a websteri, and the boring sponge Cliona. In Louisiana a so-called conch line was established by St. Amant (1938) when it was found that adult conchsdid not get much beyond the area in Barataria Bay where the salinity fell to around 20°/go. This was confirmed later by J . G. Mackin and Gunter at about 18°/oo, but has not been published. It has also been found that baby eonchs are found landward of this line. It was found by experiments that conchs were generally killed by water registering 9 /oo salinity and, additionally, that snails taken from low-salinity water survived transfer to still lower salinities or lived longer even in lethally low salinities than those coming from higher salinities. Attempts to trap conchs on oyster beds were unsuccessful because no baits more attractive than the surrounding oysters and mussels could be found, The conchs’ activity stopped at temperatures of 10°C and below. PROLOGUE Generally the human equation is not mentioned in scien- tific papers, although authors sometimes speak sharply about the data or presentation of other writers in the same field. However, it will clarify things to explain why the work described herein was begun 45 years ago and is slow in coming to an end. In barest terms, it was started under Dr. Paul S, Galtsoff in Washington and his resident assistant at the Indian Pass Laboratory, who was not noted for pro- ductivity. Furthermore, neither Dr. Galtsoff nor the writer was widely known for amiability and forbearance in those days. The upshot was that in less than eight months I turned in a report and left the employ of the U.S. Bureau of Fish- eries permanently in 1936. Publication as a bureau paper was not approved. 1 kept the manuscript with the hope of adding to it ; and have gained more information about TJiais Manuscript received July 2, 1979;acceptcd July 20, 1979. since that time. This has been used in commentary and the paper has been extended. INTRODUCTION Work was carried on from August 22, 1935, to April 15, 1936, at the Indian Pass Laboratory of the U.S. Bureau of Fisheries on Apalachicola Bay, Florida. It was planned as an integral part of the oyster pest investigation of the U.S. Bureau of Fisheries which extended from Massachusetts to Texas and ran from June 1935 to July 1936. The objectives of these studies were to determine to what extent Thais is a pest; to study its distribution and life history; and to devise a means of control, if possible. The work consisted of field studies in Apalachicola and nearby bays, but principally the former, and experiments and observations conducted in the laboratory. In the years after 1936, further observations were made in Texas, Louisiana and Mississippi. 249 250 Gunter THE ANIMAL STUDIED This snail is a prosobranchiate gastropod belonging to the order Stenoglossa. It was formerly considered to belong to the family Muricidae by taxonomists, but others separated the Purpuridae or Thaisidae from the larger group (cf. Clench 1947). The species has been variously listed in the older Litera- ture as Purpura haemastoma, P. jloridana and P. h.floridana. Johnson (1934) lists it as Thais floridana floridana Conrad. Clench (1947) considers that the United States specimens may be divided into two subspecies, Thais haemastoma floridana Conrad, which ranges from North Carolina around Florida to Pensacola and through the Indies to Venezuela, and T. h. haysae Clench, a large nodulose form living from western Florida to Texas. These subspecies are supposed to be separable generally on the basis of shell nodules (smooth to very rugged), and size. However.St. Amant (1938) found conchs in Barataria Bay which he could separate into these categories and Butler (1954) found both types in Pensacola Bay. He says that these differences will probably ultimately be shown to be environmental. Our own experience has been that there is no rhyme or reason to the distributions of these two supposedly different conchs along the Gulf coast. Conchs are variable on different reefs in the same bay and may be recognized as to reefs of origin, just as oysters are. In Apalachicola Bay in 1935, there were populations on some reefs which were no more rugose or nodulated than a Polinices shell, although they were not slick, while nodulated populations existed on other reefs in the same bay. In commenting upon these differences, in an unpublished report submitted to the Bureau of Fisheries in 1936, the author said that they indicated one of two things: either the groups from different localities do not mix with other strains or, if they do mix due to relatively wide distribution of pelagic larvae, differences in local environments cause them to grow in different ways. The latter supposition is much more likely. Cook (1895) presented data showing differences between shells of a gastropod associated with locality difference. The writer has gathered the impression that the amount of nodules present depends somewhat upon the size of the animal. There is a tendency for the Thais in the ‘‘Louisiana Marsh” region, east of the Mississippi River, to be larger and more rugose than those elsewhere; this is also a region where large oysters abound and today it is probably the largest natural oyster-producing ground on Earth. Therefore, there seems to be no reason for assigning two subspecific names to the Thais haemastoma complex in the Gulf. Conrad’s floridana is only given subspecific rank by leading American conchologists and according to Clench (1947) it is “exceedingly close to the typical form” (hae- mastoma of the Mediterranean, Africa, east and west coasts of South America, west coasts of Middle America and Mexico) from which it is said to be separable by color and being less nodulose. But since some of the northern Gulf Thais are as nodulose as any haemastoma there seems to be no good reason to adopt floridana either as a specific or subspecific name for this group. Very extensive statistical analyses, probably of larger collections than are now avail- able anywhere, must be made before the situation becomes clear. Indeed this may not suffice and other procedures such as serological, chromosome analyses, soft anatomy and life history studies may also be necessary. Such an under- taking may not be considered worthwhile for a long time to come, if ever. In the meantime it would seem the remaining conservative course is to use the only indubitably valid name, Thais haemastoma . External Anatomy The shell is a dextral, spirally coiled valve. There are seven whorls, the last and largest being known as the body whorl. Beginning near the apex and progressing spirally on the whorls is a double row of tubercles, leading to the aperture, which increase in size as they progress until they become blunt cones or nodules. They are much more pronounced in some animals than others and in some from other localities they are completely absent. The columella is straight and without a lumen. The aperture is prolonged as a short, open siphonal canal. Like all members of the Stenoglossa, Thais has a long retractile proboscis containing the odonlophoral apparatus and having the mouth opening at its extremity. Tire odonto- phoral mechanism of the Thais is doubtless similar to that of other prosobranchs, but it has not been described in print. Gunter (1936) analyzed radular movement of Thais and several other prosobranchs as a drilling mechanism. Several members of the genus Thais are known as rock shells, presumably because they are often found on rocks. However, the name is also appropriate because the shells are so hard. They are quite difficult to break with a hammer even on a rock surface, and they are opened easily only by cracking them in a vise. Nevertheless, Butler (1954) says they are cracked and eaten by hungry stone crabs (Menippc mereenaria). The writer has observed the same thing and Powell and Gunter (1968) showed that Menippe would kill and eat Thais in laboratory aquaria. In spite of their hardness, Thais shells are sometimes invaded by three kinds of shell-perforating organisms. These are the boring sponge Cliorn, the boring clam Diplothyra smithii (Martesia of most authors), and poly- chaete worms, Polydora sp. There are also little patches of closely adherent, green alga on many Thais and quite often, one or more fairly large oysters of either Crassostrea virginica or Ostrea equestris, species found on the Gulf coast. The siphon is a prolonged, roughly rectangular flap of the pallium leading out from the gill chamber, and is nor- mally folded together by the animal to form a tube. The mantle or gill chamber contains the gill and the ctenidium near the siphon. On the right side is the anus and rectal Studies of the Southern Oyster Borer 251 gland. This gland gives off a yellow mucous the function of which is unknown; it turns purple in sunlight. Before the days of the Greeks and Romans, the Minoans of ancient Crete used Mediterranean mollusks of the genus Thais and the related genera Murex or Purpura , to make the famous dye later known at Tyrian purple, which comes primarily from the rectal gland. When extended, the pedal base of the snail is a broad, rectangular organ with the operculum on the posterior dor- sal surface. The operculum completely closes the aperture when the foot is drawn in. It is made of thin, horny material. The nucleus of the operculum is lateral, The two eyes are sessile on the outer side of the base of the nonretractile tentacles. They have not been studied histologically and their grade of complexity is unknown. The eyes of Thais are not very well developed and apparently they are of use only in distinguishing light from darkness or degrees of darkness. The head consists, externally, mostly of a slightly raised portion bearing the tentacles. This part is not often exposed even when the animal is crawling about on solid surfaces. The tips of the tentacles, for about 3 or 4 mm, are smaller in diameter than the rest, and are retractile within the ten- tacles. They are black except at the very end and are prob- ably light sensitive. The pedal base is a light cream color and the upper sur- face of the flesh is a light, Finely streaked brownish-grey. The shells are various shades of yellowish-brown. The gonads are a thin sheet of tissue lying over the liver on the body coil. In the females they are of a pale yellow color tinted with orange, while in the males they are of a color best described as lavender-grey. These colors change as the breeding season approaches and become more vivid. All animals, except a very few females, have an S-shaped penis attached slightly behind and to the right of the right tentacle. This organ was observed to be large in the males, while in the females it ranges from an almost indiscernable rudiment to a size nearly as large as that of the males in some individuals. No sexual dimorphism could be discerned by general observation and several measurements made on the shell. Large Thais approach 100 mm in length in Florida and Louisiana waters. The largest specimen on record seems to be one 103 mm long from Grand Bayou, Louisiana (Clench 1947). A group of 53 “large” conchs brought in from the oyster reefs of Mississippi Sound in February 1956 ranged from 72 to 96 mm in length and averaged 82.5 mm. After being dried in room air for 2 days, the weight of these ani- mals ranged from 58 to 124 g, averaging 80.0 g. PREVIOUS WORK Ritter (1896), Kibbe (1898) and Swift (1898) mentioned among their lists of oyster enemies on the Gulf coast, a snail which they called variously, drill, conch, whelk or borer. The specific name was not given by these Navy officers but it appears that their references were to Thais, Moore (1899, p. 91) says that Purpura “causes consid- erable damage” on oyster beds in Louisiana. He placed several with oysters in aquaria but stated that they did not “molest them in any way.” He says that Tfjais ( Purpura ) “is found everywhere on the oyster beds of Louisiana excepting the less saline waters,” and that the Fishermen held it responsible for the destruction of the oysters of Chandeleur Sound. Moore (1907) later reported that Thais was not destruc- tive on the oyster bottoms of Texas. This was an error. Thais causes as much damage in Texas as it does elsewhere, Moore and Pope (1910) tried experiments by placing boxes of oysters and 77 mis together and boxes of oysters alone on oystet beds for over 2 months. When these were taken up it was found that only 2% of the spat survived and all upper valves of the dead spat which remained showed small round perforations, which were attributed to Thais. These workers also state that only spat were attacked and it is safe to say that adult oysters are not damaged due to their thicker shell. Moore and Danglade (1915, p. 41) stated that they found “practically no oysters” killed by Thais in Lavaca Bay and that they, being essentially saltwater animals, are confined to the lower part of the bay. Churchill (1920) gave a brief summary of information on Thais up to that time. The paper of Burkenroad (1931) seems to be the only one in the literature up to then concerning this animal alone. His chief findings were that’ (1) Both sizes of oysters are eaten, but the smaller ones are preferred.. (2) Mussels ( Mytilus ) are preferred to oysters. (3) Thais seems to be unable to live in water of low salinities and its range there- fore does not completely coincide with that of the mussel or the oyster. (4) During the breeding season Thais displays a strong negative geotropism so that it can be trapped at that time by driving stakes on the beds and taking them up after the animal has climbed them. St. Amant’s (1938) master’s thesis said that adult conchs lived in water with a salinity of 20°/°° or higher. This was called the conch line, J, G. Mackin and the writer have found this line to be at about 18.0% o and that small Thais live beyond the line in water of lower salinity. St. Amant found that the snails became inactive when the temperature fell to 10°C. He found them scarce on mud bottoms. Oysters were said to be the chief food. Development of the early stages was mentioned and the incubation period within the egg capsules was said to be 10 to 12 days, after which the larvae hatched. The breeding season was recorded as early March to late July with a peak in April and May. BEHAVIOR OF THAIS IN THE LABORATORY The writer has made many observations of Thais in the laboratory in Florida, Texas, and Mississippi over many years. The general conclusions are drawn together in the 252 Gunter following account. I am indebted to Ms. Judy Williams and Miss Kay McGraw for help in the laboratory and to many zoologists for long discussions, chiefly D. W. Menzet, Lyle St. Amant, J. G, Mackin, A. S. Pearse, Frank W. Weymouth, William J. Demoran and Sewell Hopkins. When first brought into the laboratory the animals are closed, sometimes completely, but usually with the siphon extending from under the operculum into the siphonal canal. When placed in tanks or jars with running sea water they usually opened and attached themselves by the foot to the substrate in less than 30 minutes. Those that did not open were dead or moribund. In cool weather animals lived in air over a week, if not exposed to the sun. In warm weather they died in 2 or 3 days under the same conditions. When placed in the air Thais would at tach to the substrate but could move very little if it was dry. They seemed to live and move about indefinitely on water tables in which the foot was submerged in only a millimeter or so of running sea water. Action of the Foot The foot of Thais progresses by small waves which start at the rear and move forward. There is an unseen division mark along the center of the foot and thus there are separate waves for each side. These start alternately and there are two waves on either side at one time. They do not extend at right angles across the foot, but are diagonal with the inner ends ahead of the lateral ends. Foot waves of gastro- pods are of various types and a classification of them was introduced by F. Vies, the French zoologist, in the early 1900s. According to this classification the foot waves of Thais are of the direct, ditaxic, alternate, diagonal type, which is virtually self-explanatory. It has been observed that the anterior margin of the foot is made up of a distinct band of tissue which undergoes a forward rippling motion not connected with the pedal waves. Thais can twist or turn the pedal base in any direction, but none was seen to crawl backwards. By shooting a strong stream of water under the foot, the writer has shown that the animals can cling to the sides of a glass jar with less than one fifth of the total area of the foot attached. The powers of suction and attraction to the substrate are local. This ability and the fact that Thais can turn and twist in any direction enables it to crawl about over oyster bars with ease. When feeding, Thais folds the front part of the foot so that it forms a short enclosed tube at its anterior portion through which the proboscis is extended. Animals in the natural state were not observed to feed with the proboscis unprotected or extended so that it could be seen, although it is possible they do, for they could be induced to do so as described below. Thais haeniastoma seems to be much more sensitive with regard to its proboscis, mouth and drilling apparatus than Melangena corona (Gunter and Menzel 1957). The latter gastropod seems to attack its victims when they are lively and far from dead, and lies about feeding with the whole proboscis extended and exposed. In contrast, r Thais is secretive and protective and in natural life seems never to have its proboscis exposed, but either retracted or covered by the foot. Demoran and Gunter (1956) thought to remove the proboscis of Thais and see how they would handle oysters then. To our considerable surprise this whole complicated apparatus was regenerated in 3 weeks time and the conchs went about cutting the edge of the oysters’ shells and killing them just as before. The pedal groove runs transversely across the anterior margin of the foot. In Ruccinum and Afurex this is the opening for glands which secrete the egg capsules (see Fretter 1941); the same is true for Purpura as shown by Pelseener (Dakin 1912). Egg laying in Thais was not observed. The foot of Thais apparently contains taste buds, as was shown for Busy con and Ilyanassa by Copeland (1918). In short, the foot functions in five known ways, namely, in locomotion, as an organ of taste, in protection of the proboscis, and probably in formation of egg capsules. It also seems to act as an accessory boring organ as shown below. Use of the Sense Organs Copeland (1918) has shown that in Busy con and Ilyanassa the osphradium is the organ of smell. This seems to be true of Thais also. When the animal is crawling about the siphon is continually moved from side to side or up and down so that it seems lobe testing the water. In all probability water drawn into the siphon is “smelled” in the gill chamber by the osphradium. Copeland (1918) has described the reactions of Busy con and Ilyanassa to food. There is a regular sequence of events which the writer has observed to be essentially the same in Fasciolaria gigantea , Busycon perversum, Melangena corona and Thais haemastoma . Although Copeland has made no such claims, these observations lead this writer to believe that the responses to food described by Copeland for the two above species are common to most carnivorous gastropods. These reactions may be described as follows: If a drop of oyster juice is placed on the tip of the siphon it contracts quickly and sharply. The animal then comes farther out of the shell and waves the siphon from side to side. If no further stimulus is given the animal begins to crawl abouL, waving the siphon meanwhile. If the stimulus came from one side the snail moves to that side. If the foot, head or tentacles are touched with a piece of oyster meat or a drop of juice, they recoil in the same manner and then the animal begins to move about. If the meat is left in contact with the foot and held so that the animal can feel it, but not fold the foot around it, the proboscis is slowly projected until it touches the meat and begins to rasp. If the meat is slowly moved down the side Studies of the Southern Oyster borer 257 Bay were sieved through three meshes of wire. The first was ordinary poultry wire, the second was galvanized wire mesh and the third was ordinary screen wire. This work was carried on from December 1935 to March 1936. No small Thais except the five listed above were found, although hundreds of small gastropods were caught, some of them being as small as 2 mm in length. The fact that all the young caught were taken on the bars seems to indicate that this is their natural habitat. Isolated specimens of large Thais have been reported from 13, 15 and 50 miles in the open Gulf, There is no explan- ation of their scarcity, unless it is that the 1935 breeding season was unsuccessful. Reliable men who have worked on the bay for years said that in some years reproduction does not take place and that the 1935 season was one of comparative scarcity of eggs. The gonads of both males and females began to thicken and enlarge in January. Previous to that time the gonads had been only thin strips of tissue over the liver coil. By the end of March 1936, the gonads were about 2 mm thick and had changed color in both sexes. Those of the female were light cream color and those of the males were of a waxy yellowish-orange color. Dr. A. S. Pearse (personal communication) observed the animals breeding in June of 1935. The last day he observed animals laying eggs was on June 1 9. He observed the animals congregated in bunches so that in some localities on St. Vincent’s Bar a half bushel of lhais were tonged in one bushel of total tonged material. salinity experiments Four sets of salinity experiments were carried out. In experiment 1, six sets of glass dishes were used con- taining two Thais and 1 liter of stagnant water. The experi- ments were started on November 19, 1935. The salinities of water in sets of dishes 1 to 6, respectively > were: distilled, 5.80, 10.93, 20.45, 30.59 and 34.19%o. The last was the same as the running sea water of the laboratory from which the animals were removed. Animals in sets 5 and 6 attached in 20 minutes. Those in set 4 opened in an average of 5 hours. No animals in the first three sets (salinities: distilled, 5.80 and 10.93) attached at all. On November 24, one animal from each jar of sets 1 to 3 were placed in running sea water of the laboratory which was approximately at a salinity of 30.99 o / O o. These all revived in 6 hours. On the tenth day one animal from each of the same sets were placed in running sea water at a salinity of approximately 25.007oo. The animal from set 3 (salinity 1 0.93) revived, while the other two did not. On the thirteenth day all of the single remaining animals in set 3 were dead. On the tenth day one animal in set 5 died from unknown causes. All other animals in sets 4 to 6 remained attached and sensitive lo touch throughout the experiment and were discarded on November 28. The temperatures and pH of the water in each jar were taken 18 times during the experiment. At the beginning of the experiment the pH of sets 1 to 6 was: 6.8, 73, 7.4, 7.7, 7.8 and 7.9, respectively. As time passed, the pH in the lower sets rose and that of the higher sets fell and on Novem- ber 28, ranged between 7.4 and 8.0, averaging 7.6 for all jars. Unfortunately temperatures could not be controlled. At the beginning of the experiments they ranged from 16.8 to 17.0°C and later rose to as high as 22 r 4°C; then fell to 9.2 and rose again to 19.4. Nevertheless, they were comparable from jar to jar and did not differ more than 0.8°C at any one time. Animals in a moribund condition were tested for sensi- tivity by pricking the siphon. If there was no reaction they were placed in sea water, where they sometimes revived. The best criterion of death was the strong putrid smell, apparently emanating from the rectal gland, which set in soon after death. No animal giving this smell ever revived in sea water although they seemed otherwise to be in the same condition as some animals which did revive. This experiment shows that Thais removed from water of comparatively high salinity (35.00°/oo) can be placed suddenly in water as low as 20.45 and after accustoming themselves, live in it. Also Thais removed from the same water and placed in water lower than salinity of 10.93°/oo cannot accustom themselves as shown by the fact they remain closed, and die. Nevertheless, they die very slowly and can survive in distilled water for at least 10 days. In experiment 2, eight battery jars were used. One liter of water and two Thais were placed in each. The latter were removed from water of salinity 32.90°/oo. The salinity of water in jars 1 to 8 was: distilled, 5.25, 10.05, 12.12, 14.00, 15.96, 19.93 and 32.90%o, respectively. All jars were aerated by glass and rubber tubing leading off from a small electric air pump. In jar 8, both animals opened in 40 minutes and remained so throughout the experiment. In jar 7, one opened in 6 hours and the other in 2 days. The latter animal closed in 8 days and was dead in 1 1 days. The remaining one closed in 15 days probably because multiplication of bacteria in the water. In jar 6, one Thais opened in 18 hours and the other in three days. They remained attached throughout the experi- ment although at the end one had the foot partly folded. Animals in jar 5 opened in 2 and 7 days, respectively, and remained so throughout the experiment. In jar 4, one specimen opened in 5 days and the other in 9 days. The latter partly folded its foot after 5 days. In jar 3, both animals opened in 7 days but partly closed two days later and remained that way. Animals in jar 2 remained closed. One revived in 12 days after being placed in sea water of salinity 27,59°/oo. The remaining one was dead by the fifteenth day. Animals in jar 1 did not open. One revived after 10 days when placed in water of salinity 28.86°/oo. The other was dead on the twelfth day. 258 Gunter On the eighth day of the experiment, it was found, due to evaporation and possibly the loss of salts by the animals, that the salinities of the jars had risen. They were in jars 1 to 8, respectively: 1.00 (estimated), 7.21, 11.92, 14.51, 16.42, 18.67, 22.11 and 35.86°/oo. They were changed in order to: distilled, 5.26. 10.01, 12.29, 13.99, 16.16, 19.79 and 27.83 0 /c»o. This apparently had little effect on the experimental animals for their behaviour was the same after as it was before the change. The experiment was stopped on December 18. At this time six of the remaining animals in the last five jars were attached. Two had the foot folded but not closed and one was dosed tight. The pH and temperatures were taken 13 times in all. The temperatures changed from 19.8 to 10.0°C and back to 17 ,1°C. There was no difference between jars greater than 0.5°C at any one time. The pH at the beginning of the experiment ranged from 6.4 in the first jar to 8.0 in the last one. The pH in the lower jars rose so that after the sixth day it fluctuated between 7.6 and 8.4 for all jars. This experiment shows that Thais removed from water of salinity around 33.00°/ O o can accustom themselves to water of salinity as low as around 1 2.00°/oo after several days. It also shows that the time taken for animals to accustom themselves roughly increases directly as the salinity decreases to the lethal or lower toleration point. Animals were not able to tolerate water of a salinity of 10.5°/oo and below, but could live as long as 10 days even in distilled water. It was found from the above two experiments that the lower salinity toleration point for Thais from water of salinity 32.00 to 34,00 c / oo , was around 10.00 to 11.00°/oo. Another experiment was devised to determine this point more exactly. This expectation was not realized, but another discovery of possibly more importance was made, as described below. The experiment was started on January 28, 1936. Three setsof two battery jars each were used. These each contained 1 liter of aerated water. The salinities from sets 1 to 3, respectively, were: 8.96, 10.03 and Il.06°/oo. Two Thais were placed in each jar. One animal in set 1 and one in set 2 did not open at all and were dead in 8 and 9 days, respec- tively. Contrary to what was expected, all ten other animals opened in from 1 hour to 2 days and remained so for 21 days when the experiment was stopped. The average time taken for the animals to open in each pair of jars from 1 to 3, respectively, was 24, 5 and 2 hours. It is seen that time increases as salinity decreases. The temperature and pi I of the water was taken 21 times during the 21 days the experiment was run. The water was changed 14 times. The salinity of that used for changes for sets 1 to 3 fluctuated between 9,00 to 9.16, 9.99 to 10.28 and 1 1 .04 to 1 1 .1 5%>o, respectively. The pH varied from 7.2 to 8.0. The temper- ature fluctuated between 15.5 and 21.8°C. The greatest difference between jars at any one time was 0.7°C. Previous to this experiment the animals used had been kept in the running sea water of the laboratory. On Jan- uary 13, this water dropped below salinity 20.00°/oo for the first time in 3 months. It was at 12.83 and down to 4.38 on January 28. The latter figure was the salinity from which the experimental animals were removed. The evident explanation then for the results obtained is that the Thais had somewhat acclimated themselves to lowered salinities in the laboratory, so that their toleration or lethal point of low salinities had fallen still lower. Federighi (1931a) found similar results working on Urosalpinx cinerea. He found that these animals from one locality died at a higher salinity than did those from other localities where the average envir- onmental salinities had been lower than in the first locality. On February 17, the foregoing experiment was stopped and the following one was started. It was really a continu- ation of the former experiment. All animals from each pair of jars were placed in one jar, making 3, 3 and 4 in jars 1 , 2 and- 3, respectively. One liter of fresh water of salinity 8.04, 9.04 and 10.04°/ O o was placed in jars 1 to 3, respectively. This water was changed using the same salinities on the third and on the fourth days. On the fifth day, the water was changed to salinities of 7.00, 7.85 and 9.04 c V oo, respec- tively. On the eighth day, this water was changed. On the ninth and fourteenth day, 100 cc of solution were removed from each jar and 100 cc of tap water added. On the fifteenth day, 1 50 cc of fresh water were added to each jar. The temperature of the water during the experiments varied between 12,4 and 24.0°C. The pH varied from 7.4 to 7.9 up to the fifteenth day when the water had turned milky. At this time pH for all three jars averaged 8.3. No water was added thereafter. All animals remained attached and opened up to the fourteenth day. From that time on the foot was partly folded. One animal in jar 3 was dead on the twenty-third day. Unfortunately, the writer was away from the laboratory at that time and when he returned on the twenty-fifth day the water was foul and the other three animals were dead, proably more from this cause than from the low salinities. Results from this jar had to be disregarded. On the same day, one animal in jar 1 was dead. On the thirtieth day, all animals in jar 1 and two of those in jar 2 were dead. The salinities of these jars were 6.22 and 6.88°/oo, respectively. The remaining animal in jar 2 was sensitive to pricking 4 days later when, due to evapoation, the salinity of the water had risen to 7.4l Q /oo, This was lowered to 5.75°/oo and the next day the animal was dead. This experiment shows that Thais can accustom them- selves to and live in water of salinities as low as 7.00°/ O o if it is lowered slowly, but died when the salinity reaches a point around 6.5%o. FIELD EXPERIMENTS On December 10, 1935, boxes containing Thais were placed at six stations. These stations were on Hiles’ Shallow Bar near Indian Pass, Picolyne Bar, north end of St. Vincent’s Studies of the Southern Oyster Borer 259 Bar, south end of St. Vincent’s Bar, Platform Bar and a small bar in East Bay. Each box was constructed of poultry wire over a wooden frame. Two were put down at each place. One of these contained 8 Thais and the other contained 8 Thais and 25 adult oysters. These were visited an average of five times each between December 10, 1935 and Feb- ruary 26, 1936. About January 13, flood waters from rivers above Apalachicola came into the bay and the salinities as a whole took a precipitous drop. Before this date, 10 oysters died from natural causes or were eaten by the Thais within the cages. No Thais died. From January 13 to February 26, when the salinities were low, 4 oysters died and 36 Thais died. Twenty-five of the Thais casualties were on the north and south of St. Vincent’s Bar and East Bay which were areas of the lowest salinity. Twenty -two of the dead Thais were in boxes containing oysters so it cannot be said that they starved to death. The bottom salinities taken from these stations dropped to a little above 9.0 %q. This experiment apparently proves that under natural conditions on the beds, oysters will survive lower salinities than Thais so that the range or habitat of oysters is, ot may be in part, in areas where the average salinities are lower than Thais can tolerate. This fact was also proven still more conclusively by natural events, for on February 17, 1936, Thais on St. Vincent’s Bar were seen to be dying. Freshly dead, undecayed animals were taken at this time. From then until February 27 they died in great numbers. On this last date, two apparently moribund animals revived when brought to the laboratory. Since February 27, all Thais shells taken on this bar have been empty. Apparently, Thais has been exterminated here by fresh water, while most of the oysters lived, although there were some casualties. In March 1936, 41 bushels of material were tonged from 16 bars. Thais were taken only on Hiles’ Shallow Bar near Indian Pass and it seems that this was the only place where they were present in Apalachi- cola Bay. Events of that nature seem to happen over and over on the Gulf coast, and result in the killing out of Thais and survival of oysters in low-salinity waters following high water or Hood periods. They are particularly noticable in Mississippi and Louisiana (Viosca 1928, Gunter 1953). ENEMIES The stone crab, Menippe mercenaria, can kill and devour Thais as noted above (Powell and Gunter 1968). Butler (1954) has stated that hermit crabs kill these conchs and Percy Viosca (personal communication) told the writer that several hermit crabs gathered around Thais and pinched their tentacles until they bled to death, after which they pulled the body from the shell and took it for their own. MISCELLAN1A Gastropod mollusks have existed since the upper Cambrian. As stated previously in this paper, the radula and, by the same token, the odontophore are present in every molluscan class except the Pelecypoda. Even so, as Krutak (1977) has pointed out. the radular teeth of gastropods have not been reported as fossils. This is quite strange insofar as the gastropod mollusks are organisms of vast abundance in the seas. This puzzle is explained if it is assumed that the conodonts, a group with no-known relatives or relations, are really the radular teeth of gastropods and other mollusks, extending back almost to the beginning of annual fossils in the Cambrian age. REFERENCES CITED Bayliss, William Maddock. 1927. Principles of General Physiology. Longmans, Green, and Co. Ltd. London. 882 pp. Burkervroad, Marlin D. 1931 Notes on the Louisiana conch, Thais haenmtoma Linn., in its relation to the oyster Ostrea virgin ica. Ecology X1I(4):656 664. Butler, Philip A. 1954. The southern oyster drill. 1953 Proc, Nat. Shelfish. Assoc. 44:67 75. Carriker,M. R. 1943. On the structure and function of the proboscis in the common oyster drill, Urosalpinx cincrca Say. / Marphol . 73:441-506. _____ , Dirk Van Zandt & Garry Charlton. 1967. Gastropod Urosalpinx: pH of accessory boring organ while boring. Science 158(3803)1920-922. Clench, William J. 1947. The generaPurpura and Thais in the Western Atlantic. Johnsonia 2(23) :6 1—91. Cook, H. A. 1895. The Cambridge Natural History, Molluscs, etc. Ed., Harmer, S. F. and Shipley, A.E.; Macmillan and Co., New York and London. 111:209-243. Copeland, M. 19 18. The olfactory reactions and organs of the marine snails Alectrioh obsoleta (Say) and Busycon canaliculatum (Linn .).J. Exp.Zoo. 25:177-277' Churchill, E. P. 1920. The oyster industry of the Atlantic and Gulf Coast. U.S. Comm. Fish. Rept. 1 9 19(1 921), Appendix VII, 5 5 pp. Dakin, W. J. 1912. Buccinurn, the whelk. Liverpool Marine Biology Committee Memoirs. London : Williams & Norgate. No. 20, 1 1 4 pp, Danglade, E. 1917. Conditions and extent of the natural Oyster beds and barren bottoms in the vicinity of Apalachicola. U.S. Comm. Fish. Rept. (1916), Appendix, pp. 1-78. Demoran, William & Gordon Gunter. 1956. Ability of Thais haemastoma to regenerate its drilling mechanism. Science 123(3208): 11 26. Dubois, R. 1909. Isomorphisme et isoebromatisme symbiotiques chez certains Lamellibranches marins. Bulletin de TInstitue General de psychologic 9 e annee, No. 4, 1909. Fedcrighi, II. H, 1931a. Studies on the oyster drill, Urosalpinx cinerea (Say). Bull. U.S. Bur. Fish , 47:85-115. . 1931b. Salinity death - points of the oyster drill snail Urosalpinx cinerea (Say ). Ecology 1 2(2):346— 35 3. Fischer, P. H. 1922. Sur les gasteropodes perceurs. J. Conchyliol. 67:1-56. Fretter, V. 1941. The genital ducts of some British stenoglossan prosobranchs. /. Mar. Biol. Asso. UK. 25:173-211. Gunter, Gordon. 1936. Radular movements in gastropods, /. Wash. Acad. Sci. 26(9) : 36 1 -365. 260 Gunter , 1952. Radular movement and boring efficiency of gas- tropods. Nature 169:630. . 1953. The relationship of the Bonnet Carre spillway to oyster beds in Mississippi Sound and the “Louisiana Marsh,” with a report on the 1950 opening. Publ. Inst. Mar. Set. Univ. Tex. 3(1): 17-71. & R. W. Men?, el. 1957. The crown conch, Melongena corona, as a predator upon the Virginia oyster. Nautilus 70(3): 84' 87. Herrick, J. C. 1906. Mechanism of the odontophoral apparatus in Sycotypus canaliculatus. Am. Nat. 40:707-737. Hibaya, T„ E. Iwai & Y. Hashimoto. 1953, Comparative studies on the Stomachal plates and crystalline style - II. Structure of the stomachal plates of Dolabella scapula. Bull. Jpn . Soc. Sci. Fish. 19:1-4. Huxley. T. H. 1853. On the morphology of the cephalous Mollusca. Philos. Trans. R . Soc., bond. B. Biol. Sci. Pp. 601 638. Jensen, A. S. 1951a. Do the Naticidae (Gastropoda: Prosobranchia) drill by chemical or by mechanical means? Vidensk. Medd. Dan. Naturhist. Foren. 1 1 3:25 1-261. . 1951b. Do the Naticidae drill by mechanical or by chemical means? Nature 1 67 : 901 . Johnson, C. W. 1934. List of the marine molluscs of the Atlantic coast from Labrador to Texas. Proc. Boston Soc. Nat. Hist. XL(1):1 1 8. Kibbe, I. P. 1898. Oysters and oyster culture in Texas. Bull U.S. Fish. Comm. XV11(1 897):313-314. Krutak, Paul R. 1977. Gastropod radulae: their potential in the fossil record. Trans. Gulf Coast Assoc. Geol Soc. XXVII: 314-322. Menzel, R. Winston & Sewell H. Hopkins. 1954. Studies on oyster predators in Terrebonne Parish, Louisiana. Texas A&M Research Foundation. Project 9, pp. 1—145. McGraw, K. A. & G. Gunter. 1972. Observations on killing of the Virginia oyster by the Gulf oyster borer, Thais haemastoma, with evidence for a paralytic secretion. Proc. Nat, Shellfish. Assoc. 62:95-97. Moore, Donald R. 1956. Observations of predation on echinoderms by three species of Cassididae. Nautilus 69(3):73 — 76. Moore, H. F. 1899. Report on the oyster beds of Louisiana. Rept. U.S. Fish Comm. 24(1 898) :49- 100. . 1907. Survey of oyster bottoms in Matagorda Bay, Texas. Rept. U.S. Fish Comm., Bur. Fish Doc. No. 610(1905). 86 pp. & T. B. Pope. 1910. Oyster culture experiments and investigations in Louisiana. Rept. U.S. Fish Comm., Bur. Fish Doc. No. 731 (1 9 1 8): 1 — 52. & E. Danglade. 191 5. Conditions and extent of the natural oyster beds and bottoms of Lavaca Bay, Texas. Appendix II. Rept. U.S. Fish Comm. 1914:1-45. Oswald, A. 1894. Der Russelapparat der Prosobranchier. J. Z. Naturwiss. 28:118-1 62. Preyer, W. 1866. Ueber das fur Speichel gehaltene Sekret von Dolium galea. Sitz. Ber. niederrhein. Ges. Natur. Heilkunde in Bonn. Pp. 6-9. Powell, Earnest H., Jr. &. Gordon Gunter. 1968. Observations on the stone crab in the vicinity of Port Aransas, Texas. Gulf Res. Rept. 2(3):285-299. Ritter, H. P. 1896. Report of a reconnaissance of the oyster beds of Mobile Bay and Mississippi Sound, Alabama. Bull. U.S. Fish Comm. XV(1895):325-339. Schiemenz, P. 1891, Wie bohrt Natica die Muscheln an? Mitt. Zool. Sta.Neapel 10:153-169. Swift, F. 1898. The oyster-grounds of the West Florida coast; their extent, condition, and pecularities. Bull. U.S. Fish Comm. XVIKl 897):285-287. St- Amant, Lyle S. 1938. Studies on the biology of the Louisiana oyster drill, Thais haemastoma haysae. Master’s thesis. Louisiana State University. Viosca, Percy, Jr. 1928. Flood control in the Mississippi Valley in its relation to Louisiana fisheries. La. Dep. Conserv. Tech. Pap. 4:1 • — X6. Gulf Research Reports Volume 6 | Issue 3 January 1979 A Study of Four Oyster Reefs in Mississippi John Ogle Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.06 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation OgleJ. 1979. A Study of Four Oyster Reefs in Mississippi. Gulf Research Reports 6 (3): 261-265. Retrieved from http://aquila.usm.edu/gcr/vol6/iss3/6 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(S>usm.edu. Gulf Research Reports, Vol. 6, No. 3, 261-265, 1979. A STUDY OF FOUR OYSTER REEFS IN MISSISSIPPI JOHN OGLE Oyster Biology Section, Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564 ABSTRACT A study of four oyster populations in Mississippi over 13 months (May 1978-May 1979) indicates that although oysters are sexually developed during most of the year (10 months), setting was variable in intensity , dependent upon location, and limited in all cases to one or two months. Mortality was variable, dependent upon location and was attributed to high predation at one station and to harvesting and fresh water at the other stations studied. Suggestions for management are discussed. INTRODUCTION The oysters and the oyster industry of Mississippi have been the subjects of numerous investigations dating back to the early part of the century. However, data that are avail- able consist of oyster bottom surveys and studies of setting. The densities of oysters on various reefs have been mentioned (Moore 1913, Engle 1948, MacKenzie 1977). An evaluation of different cultch materials (Veal, Brown, and Demoran 1972) conducted during 1971 and 1972 was invalidated by the lack of a spat set. During seven months of 1972, spat setting was monitored on fouling plates at one station in Bay St. Louis, MS (Haburay 1977). Setting was monitored on fouling plates at five stations in Mississippi Sound for one year (October J976-Qctober 1977)and that same study (McGraw, personal communication) provided information on the growth rates of oysters. However, only one of the five stations was near a commercial reef (Biloxi Bay). With recent interest in managing, developing and exploit- ing oysters, this lack of basic information has become apparent. This study was conducted to determine condition, setting, growth and mortality of oysters at four reefs in Mississippi, MATERIALS AND METHODS One-cubic-foot samples of reef material were collected monthly for 13 months at four stations: a lagoon at Horn Island, Graveline Bayou, a closed reef in Biloxi Bay, and a tonging reef at Pass Christian. The oysters at Horn Island are harvested publicly for recreation; the reefs at Graveline and Biloxi Bay are dredged for relaying and the reef at Pass Christian is harvested commercially. The Graveline and Pass Christian samples were dredged, while the Horn Island and Biloxi Bay samples were handpicked in shallow water. The number and size of all live oysters were determined and enumerated into four 25-mm-size classes: spat , seed , juvenile, and market sizes (Hofstetter 1977). The number of fresh single valves and boxes was determined and the percent of dead shell material was calculated. The average condition index was calculated according to the procedure of Hopkins (1949) with the shell cavity volume being determined according to the procedure of Galtsoff (1964). Gonadal development was determined on ten oysters by noting the condition of a gonadal smear. Hydrographic data, including temperature determined to the nearest degree Celsius and salinity determined to the nearest ppt with an American Optical toLal solids refractometer, were recorded for each station monthly. RESULTS Graveline oysters had the highest condition index (Table 1) throughout most of the study while Horn Island oysters had the lowest condition. Generally, oysters for all four stations had similar seasonal trends. Condition was high during May of both years (1978, 1979), However, values were also high during November 1978 and March 1979 for all stations. Values were low during the summer of 1978 and again during January 1979. Sexually developed oysters were found during ten months of a yearly period for at least one of the four stations (Tabic 1). January and February were the only months for which no sexually developed oysters were found at any station. Horn Island oysters were developed the greatest number of months (10 of 13) while oysters from Biloxi Bay and Graveline were developed during 8 of 13 months sampled. Setting of larvae, based upon spat set on shells, was variable in intensity, dependent upon location and limited to a couple of months. Spat were first noticed during July at Pass Christian with a peak of setting during August. Oysters at Graveline Bayou did not set until November with a peak showing up in the December sample. Setting was most pronounced at Horn Island with a peak during August. An additional set occurred during November at that station. A very low set occurred during August at Biloxi Bay. Growth of size classes was difficult to follow at Biloxi Bay due to the insignificant set, and at Graveline due to the late set in 1978. Growth of oysters at Horn Island was faster than growth at Pass Christian. Oysters which set during August at Horn Island were seed size in 5 months and had started to show up in the juvenile size class in 9 months (Table 2). Oysters which set during July at Pass Christian were seed size in 6 months and were showing up in the 261 Manuscript received August 31 , 1979; accepted September 28, 1979. 262 Ogle TABLE 1 . Average condition index and percent sexually developed oysters based upon ten oysters from four reefs in Mississippi over a 1 3-month period. 1978 1979 Station May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Condition Index Biloxi Bay 7.83 6.40 4.55 5.68 5.31 6.04 8.53 7.74 4.72 7.65 11.80 9.10 13.34 Graveline 7.46 7.19 5.68 4.68 6.28 10.01 16.80 13.54 11.19 13.09 16.80 10.60 11.69 Pass Christian 8.24 4.74 4.56 5.59 5.22 5.51 12.13 8.08 11.00 9.43 17.00 10.00 9.78 Horn Island 6.60 6.63 4.56 3.97 6.09 4.04 7.21 7.78 7.78 7.19 8.80 8.34 6.09 Percent Sexually Developed Oysters Biloxi Bay 90 100 100 90 70 10 0 0 0 0 0 70 80 Graveline 30 100 80 100 80 40 0 0 0 0 0 10 88 Pass Christian 80 100 50 80 70 50 20 40 0 0 0 90 100 Horn Island 40 50 90 100 100 20 0 20 0 0 0 90 90 TABLE 2. Size frequency distribution of live oysters contained in a standard (1 cubic foot) dredge sample. Percent Size Distribution 1978 1979 May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Spat (0-25 mm) 1.9 2.0 1.7 7.0 1.0 Biloxi Bay 2.9 3.6 6.0 1.8 1.2 2.1 1.7 4.8 Seed (26-50 mm) 63.4 23.0 33.5 18.5 16.0 15.1 16.5 24.0 17.2 12.5 45.7 21.1 20.8 Juvenile (51-75 mm) 23.8 35.0 39.1 57.3 44.3 52.7 44.4 32.0 38.4 43.4 44.3 38.6 48.8 Market (75 mm) 12.9 40.0 25.7 17.2 38.7 29.3 35.5 38.0 42.6 42.9 7.9 38.6 25.6 Spat (0-25 mm) 1.4 0.8 1.2 8.2 8.3 Graveline Bayou 1.1 56.3 64.8 49.8 53.9 59.9 55.0 56.9 Seed (26-50 mm) 21.3 13.3 25.9 17.0 19.0 46.3 14.7 9.3 14.8 10.4 10.1 11.3 14.1 Juvenile (51 75 mm) 28.1 40.7 31.3 32.7 31.0 37.9 11.3 14.6 15.5 11.4 11.9 14.1 14.0 Market (75 mm) 49.2 45.2 41.1 42.1 41.7 14.7 17.7 11.3 19.9 24.3 18.1 19.6 15.0 Spat (0-25 mm) 6.4 1.9 41.5 51.8 40.9 Pass Christian 26.2 19.4 15.3 14.3 10.7 12.9 13.5 7.7 Seed (26-50 mm) 28.2 23.5 11.8 9.4 19.8 5.0 9.2 13,3 73,2 16.6 29.5 18.9 27.8 Juvenile (51-75 mm) 30.9 26.1 17.8 17.6 26.6 18.8 10.2 16.3 7.2 19.8 37,6 15.3 28.9 Market (75 mm) 34.5 48.5 28.9 21.2 12.7 50.0 61.2 55.1 5.3 52.9 20.0 52.3 35.6 Spat (0-25 mm) 34.9 12.9 19.1 73.0 46.7 Horn 56.0 Island Lagoon 63.1 35.2 52.5 56.0 50.2 51.5 29.5 Seed (26 50 mm) 48.3 73.9 62.7 25.0 29.0 19.0 20.6 31.8 39.4 32.2 46.1 22.7 40.8 Juvenile (51-75 mm) 13.6 10.8 17.1 2.0 18.3 7.0 13.9 26.5 7.6 11.0 3.5 17.7 22.1 Market (75 mm) 3.2 2.4 1.2 0.0 6.0 17.7 2.4 6.5 0.5 0.8 0.2 8.1 7.6 A Study of four Oyster Reefs in Mississippi 263 juvenile size class in 10 months. The November set of oys- ters at Horn Island had reached seed size in 4 months. Horn Island contained the fewest marketable oysters, while Pass Christian had the most market-size oysters (Table 2). The greatest number of marketable oysters was typically found during the fall months. Graveline Bayou was depleted of marketable oysters during October due to dredging. The amount of dead shell was high for Pass Christian, but the most dead shell occurred at Gravelinc after it was dredged. Horn Island contained almost no dead shell mater- ial (Table 3). Monthly mortality was high for Horn Island and Pass Christian (Table 4). Horn Island oysters experienced high mortality during June, July, August, January, March and April. Pass Christian oysters experienced high mortality dur- ing October, November, December and January, and again during March, April and May. Graveline oysters experienced a high mortality during October, while the highest mortality for Biloxi Bay oysters was during August. The highest temperature (34°C) was recorded for Biloxi Bay whereas the lowest temperature (6 a C) was recorded for the lagoon at Horn Island (Table 5). The highest recorded salinity (32 ppt) was for Horn Island while fresh water occurred at Graveline and Pass Christian. The lowest salin- ity recorded for Biloxi Bay was 4 ppt and the lowest salinity recorded for Horn Island was 10 ppt. DISCUSSION The oyster population at Horn Island should be consid- ered marginally harvestable. Reproductive potential was greatest at that station with two sets of spat occurring during the year, but there was not much cultch for the spat to set on. That resulted in the elongated shells and large clusters of oysters characteristic for areas of soft, muddy bottoms. Oyster growth in the lagoon was rapid but there were few market-size oysters, indicating a high natural predation and mortality. Oyster drills were probably the major cause of mortality. The protozoan parasite Perkinsus marina, respon- sible for oyster mortalities in areas of high salinity, especially during warm months of the year, was not prevalent during this study (Ogle, unpublished manuscript). The lagoons of Horn Island could be evaluated as spat-collecting areas uti- lizing artificial spat collectors. The oysters at Graveline were generally the best oysters in Mississippi during this study period. The great number of large-sized oysters and their good condition was offset only by their being in an area closed to harvesting. The area was last harvested during February 1974 (W, J. Demoran, per- sonal communication). Harvesting of the bayou during October of this study period for relaying of the oysters afforded the author the opportunity to investigate the effects of dredging on a reef and the effect of relaying oysters to new beds (Ogle 1979). Dredging of the bayou reduced the number of adult oysters and increased the percentage of dead shell, as would be expected. The highest monthly mortality was also recorded during the month that dredging occurred. These effects were offset by an excellent set of spat the month following dredging. Graveline Bayou, being protected from adverse weather and accessible to small craft, would make an excellent tonging reef. Consideration should be given to eliminating the sources of pollution into the bayou. This area would then serve eastern Mississippi, which presently has no commercial open oyster reefs. Biloxi Bay, another closed oyster area, was dredged for relaying oysters during September and October. Dredging occurred adjacent to ihe sampling station, so effects of dredging were not recorded in this study. Biloxi Bay has been heavily dredged during the past several years. There was no significant spat set during this study and growth is known to be slow in this area, requiring 2 to 2Vi years to produce market-size oysters (Ogle, unpublished data). The oyster bottom should be resurveyed to insure that it is not being overharvested and restrictions placed on the taking of oysters from this area. Pass Christian was the only commercially harvested reef in this study. Harvesting occurred from September until April with heaviest tonging during October, November, December and January-rnonths for which mortalities were also high. Interestingly, these were also months with the highest percent of marketable oysters. Mortalities during March, April and May were attributed to low-salinity waters from the flooding of the Pearl River and the opening of the Bonnet Carre Spillway on April 16, 1979. Should fresh water persist and mortality increase, planting of seed oysters may be required. This study should be considered preliminary due to its limited scope and duration. In order to study the dynamics of a population adequately, especially oysters which require 2 years to reach a marketable size, several year classes should be followed over a period of several years. In addition, only four reefs were studied. Sampling should be expanded to cover all the major reefs in Mississippi. Because of the nonrandom nature of oysters on bottoms, the use of a standard volume sample only provided an indication of population dynamics. These data can then be used with surveys of the extent of oyster bottoms to estimate total oyster populations. The last survey of oyster reefs in Mis- sissippi was completed in 1977 and should continue to be updated periodically. ACKNOWLEDGMENTS I would like to thank Mr. John Supan, who collected most of the samples in this study, and Ms. Kathy Flurry who worked up those samples. 264 Ogle TABLE 3. Composition of a standard (1 cubic foot) dredge sample. 1978 1979 May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Biloxi Bay No. live 101 198 179 157 199 205 169 188 162 128 140 171 125 No. boxes 5 22 37 57 14 17 22 15 16 14 9 14 13 No. valves 17 11 48 60 3 6 26 17 9 7 6 11 11 % Dead shell 50.0 t* 16.7 16.7 t 4.0 8.3 8.3 4.2 t t 12.5 50.0 Graveline Bayou No , live 142 135 166 159 168 95 300 398 291 202 277 327 266 No. boxes 16 15 10 4 11 2 6 12 15 22 8 15 9 No. valves 32 28 38 33 19 89 88 60 38 36 30 11 12 % Dead shell 9.0 8.3 17.0 8.0 4.0 58,3 41.6 25.0 25.0 33.3 25.0 25.0 34.3 Pass Christian No . live no 157 135 245 196 80 108 98 56 121 85 111 90 No. boxes 3 10 2 18 8 30 46 40 20 15 7 25 34 No. valves 38 41 60 65 79 42 67 50 49 17 63 18 7 % Dead shell 25.0 20.8 50.0 41.6 50.0 33.0 17.0 33.0 42.0 16.7 50.0 33.3 50.0 Horn Island Lagoon No. live 469 372 346 697 345 425 846 381 620 763 864 260 569 No. boxes 69 169 93 191 19 37 68 62 400 109 226 83 94 No. valves 5 4 10 9 7 4 7 8 3 8 5 6 1 % Dead shell t t 4.0 t t t t t t t L t t *t - trace of shell TABLE 4. Percent monthly mortality based upon fresh boxes and valves contained in a standard (1 eubic foot) dredge sample. 1978 1979 Station May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Biloxi Bay 11.8 12.2 25.4 35.6 7.2 8.9 17.2 111 11.2 9.4 7.9 10.2 12.9 Graveline 18.4 17.7 14.9 11.4 10.9 32.8 14.3 9.5 10.5 7.9 7.6 5.9 5.3 Pass Christian 16.7 16.3 19.1 17.0 19.5 38.9 42.4 39.8 44.3 16.3 31.2 23.4 29.4 Horn Island 13.2 31.5 22.0 21.9 6.1 8.4 7.8 14.8 24.5 12.9 20.9 24.8 14.2 TABLE 5. Temperature (°C) and salinity (ppt) determined monthly for four stations in Mississippi over a 13-month period. 1978 1979 Station May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Temperature; Salinity Biloxi Bay 29; 6 34; 6 32; 8 29; 16 26; 18 23; 22 18; 26 1 1 ; 20 7; 16 13; 4 22; 4 20; 10 23; 8 Graveline 22; 18 30; 6 32; 11 28; 16 25 ; 19 23; 24 17; 21 11 ; 12 8; 15 10; 2 14; 5 19; 0 25; 2 Pass Christian 22; 17 28; 12 28; 18 28; 14 27; 18 23; 18 17; 18 11; 15 10; 16 15; 5 19; 5 20; 5 26; 0 Horn Island 24; 16 30; 12 24; 22 30; 25 - ; 22 14; 28 19; 32 12; 24 12,26 6; 11 16; 14 25; 10 26; 13 A Study of Four Oyster Reefs in Mississippi 265 REFERENCES CITED Engle, J. B. 1948. Investigations of the oyster reefs of Mississippi, Louisiana and Alabama following the hurricane of September 19, 1947- U.S Fish Wildl. Serv. Spec. Sci. Rep. 59, 79 pp. Galtsoff, P. S. 1964. The American oyster, Crassostrea virginica Gmelin. U.S. Fish Wildl. Serv. Fish. Bull. 64, 480 pp. Haburay, J. K. 1977. An investigation of the establishment of sessile marine communities, St. Louis Bay, Hancock County, Mississippi. Ph.D. dissertation. University of Southern Mississippi. Hofstelter, R. P. 1977. Trends in population levels of the American oyster Crassostrea virginica Gmelin on public reefs in Galveston Bay, Texas. Tex. Parks Wildl. Tech. Ser. 24, 90 pp. Hopkins, A. E. 1949. Determination of condition of oysters. Science 1 10:567-488. Mackenzie, C. L. 1977. Development of an aquaculture program for rehabilitation of damaged oyster reefs in Mississippi. Mar. Fish. Rev. 1259, 39(8). 13. Moore, 11. F. 1913. Condition and extent of natural oyster beds and barren bottoms of Mississippi Sound. U.S. Bur. Fish. Soc. 769, 61 pp. Ogle, J. T. 1979. Effect of dredging and relaying oysters in Missis- sippi Sound. J. Miss. Acad. Sci. 24(Sup,):l 18. . Occurrence and seasonality of Perkinsus marinus (Pro- tozoa: Apicomplexa) in Mississippi oysters. Gulf Coast Research Laboratory, Ocean Springs, MS. Manuscript in preparation. Veal, C. D., W. H. Bown & W. J. Demoran. 1972. Developments in off bottom oyster culture in Mississippi. Am. Soc. Eng. 1972: 72 575. Gulf Research Reports Volume 6 | Issue 3 January 1979 Marine Fishes of Panama as Related to the Canal Gordon Gunter Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.07 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Gunter, G. 1979. Marine Fishes of Panama as Related to the Canal. Gulf Research Reports 6 (3): 267-273. Retrieved from http://aquila.usm.edu/gcr/vol6/iss3/7 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(S>usm.edu. Gulf Research Reports, Vol. 6, No. 3, 267-273, 1979. MARINE FISHES OF PANAMA AS RELATED TO THE CANAL GORDON GUNTER Gulf Coast Research Laboratory ; Ocean Springs, Mississippi 39564 ABSTRACT Recent papers by Eskinazi, compared to studies made on the Texas and Louisiana coasts 35 to 45 years ago and on the south Atlantic coast 15 years ago, show remarkable similarities of the estuarine fishes of northeastern Brazil and the northern Gulf of Mexico. Forty-five of 48 families of the two areas are in common and about 35% of the species arc in common. On the west coast even greater correspondence might be expected between fishes of Peru and southern California, were it not for the restriction of tropical fishes by the Humboldt and California currents. When the lithospheric plate under North America pulled away from Pangaea, strong swimmers and pelagic fishes main- tained connections. Thus, the marine fishes have had strong connections for the last 70 million years. Further, the Pacific and Atlantic faunas were connected until the mid-Pliocene when Isthmus America became continuous about 5.7 million years ago. Marine euryhaline fishes are much more abundant than their freshwater counterparts. Thus large numbers of marine fishes are found in the fresh waters of Panama. One hundred thirty-seven (137) marine fishes have been found there and 57 species have taken up more or less permanent residence. No freshwater fish have taken up residence in the seas of Panama. The freshwater fishes of Central America came from the south and their movement has been very slow. Isthmus America was a ridged mountainous area with short, small rivers and small basins. The estuaries were small or nonexistent. Thus, one avenue for spread of fishes from fresh water was generally nonexistent. There are 32 river basins in Panama and fish have little access from one to the other. So the river basins have an insular aspect. The Canal runs through only three river basins. There are generally no problems to the passage of freshwater fishes in the Canal but they are stopped by even low salinity and, if back pumping becomes necessary to maintain the lakes used in the operation of the locks, most fresh- water fishes will not traverse the Canal. Thus, it may be said that there is little chance of transfer of freshwater fishes from one coast to the other. However, the tarpon has already crossed the isthmus and eight other species, including blennies, gobies and pipefishes, have made the passage according to ichthyological collectors. Actually only four fishes are indubitable crossers. Back pumping will increase the potentiality a great deal but no foreign process of gene flow or heredity other than what is present all over the world today and which was present when the Pacific and Atlantic were connected, is to be expected. Thus a sea level canal would present a new situation but nothing that could be antibiologrcal or deadly. COMMINGLING OF FISHES BETWEEN NORTH AND SOUTH AMERICA The zoogeography of marine and freshwater fishes are quite different affairs, and nowhere is this shown more clearly than in a comparison of the coastal fishes popula- tions of northern South America and southern North Amer- ica with parallel comparisons of the freshwater fishes of the same regions. The question is touched upon here because it relates to the composition of the fishes of Panama. MARINE FISHES Data concerning the coastal ichthyological fauna of north- eastern Brazil which were recently presented by Eskinazi (1972, 1974) show the remarkable resemblance between the genera and species of coastal fishes of northeastern Brazil and the coasts of Louisiana and Texas as described by Gunter (1938a, 1938b, 1941, 1945). The northern Gulf of Mexico lies in the so-called Carolinian Biogeographic Province which also includes the Caroiinas, Georgia and northern Florida on the Atlantic. The similarity of the shallow-water fish fauna of the Atlantic and Gulf coasts of this province is now well known. Possibly the best listing of the Atlantic ichthyofauna of this region for comparative purposes is that of Anderson and Gehringer (1965), although Manuscript received May 7, 1979; accepted May 14, 1979. it concerns the Cape Canaveral area which is at about the southern border of the Carolinian. A thorough comparison of shallow-water marine fishes of North and South America would be worthwhile, hut that subject is not the concern of this paper. However, a cursory comparison of the species listed by Eskinazi (1974) for northeastern Brazil shows that about 35% of the species along those shores are the same as those off the northern Gulf coast of the United States. Similarly, genera coincide closely and, with regard to Brazilian families, only the Cichlidae, the Erythrinidae and Symbranchidae, freshwater families which are sometimes taken in low-salinity coastal waters of Brazil, are excluded from the northern Gulf. The latter two come to southern Mexico and one comes to Florida and one cichlid has reached Texas fresh waters. Thus 45 of 48 families of the two areas are in common. The strong similarity between the shallow-water marine fishes of the North American east coast, south of Cape Hatteras, and northeastern Brazil is impressive and it may be said that strong ichthyofaunal connections extend from subtropic zone to subtropic zone, inclusively. On the western coasts of the Americas an even greater correspondence of the marine, shallow- water ichthyofauna from southern California to Peru might be expected because of more equable (low) water temperatures and (high) salinities and a generally more similar environment as a 267 268 Gunter whole, with rocky shores, few estuaries and a narrow shelf. However, Rosenblatt (1967) points out the restriction of the tropics by the Humboldt and California currents on the west coast of the hemisphere. The geographic reasons for the relations of the coastal fishes of the Americas is worth a short examination. The lithospheric plate under the North American continent began to pull away from the great land mass of Earth before South America did (Raven and Axelrod 1975) and the two continents were well apart (approximately 3,000 kilometers) during most of the Cretaceous Era, for about 100 million years beginning about 150 million years ago. During that period pelagic fishes and strong swimmers maintained connections over the area. Later, near the end of the Cretaceous Era (cf. Dengo 1973), a series of volcanic and nonvolcanic islands arose which connected the two continents along lines of the future isthmus. This came about some 70 million years ago. Then the shore species of fishes, well separated and differentiated over some 80 million years or so, including the weakly motile botton>d weilers, spread between the two continents by rafting and the other accidents of biological spreading, which become significant over long periods of time.“Rafting” by fishes would consist of floating along underneath, hiding in crevices or even clinging beneath the “raft” and as such would seem to be more common and successful than for air-breathers. Thus it may be said that the estuarine fishes of North and South America have had fairly strong connections for approximately 70 million years and possibly more. Further- more the Pacific and Atlantic faunas of both continents were not separated until the mid-Pliocene when Isthmus America began as an unbroken connection between the two continents (Emiliani et al. 1972). That was about 5.7 million years ago. Marine fishes of Panama are a section of a vast inshore fauna which extends from subtropic across to subtropic on either side of the equator and on both the Atlantic and Pacific coasts. It is composed of several hundred species, a few of which are no doubt still unknown. These were gener- ally treated by Meek and Hildebrand (1923-28), who listed 757 species. Details of the history of the study of the fishes of Panama have been given by Loftin (1965). Actually* the chief interest here is in the euryhaline marine fishes, those which are capable of with standing fresh water. There are not a great many euryhaline species in the strict terms defined by Gunter (1942, 1956), but there are a great many species which tolerate some admixture of fresh water and sea water. Gunter defined a fully euryhaline species of fish as one which has been recorded in both pure fresh water and pure sea water by competent observers. In comparison the partially euryhaline fishes which tolerate mixtures of fresh water and sea water enter from both fresh water and the ocean. However, Gunter pointed out that the marine invaders are much more numerous. In fact the estuarine fauna is predominantly of marine origin all over the whole world. Miller (1966) lists 137 species of marine fishes which are to be found in the fresh waters or almost fresh waters of Panama, and he states that in the whole of Isthmus America approximately 57 species, or one-third of the marine invaders, have taken up more or less permanent residence in fresh water. With regard to “pure fresh water,” all water from land and even rain water contains some mineral salts. The only boundary between sea water and fresh water which is objec- tive and chemically determinable, is at the concentration where the ratio of the chloride ion to the other ions changes from that of sea water to that of fresh water (Price and Gunter 1964). On coasts with drainage over silicate rocks and sediments the water is “soft” and the ratio change takes place at near 0.1 8% 0 . On coasts where the drainage is over carbonate rocks and the fresh water is “hard” the salinity at the change point to fresh water may be near 0.6?oo saline or higher than oligohaline sea water* of other areas. FRESHWATER FISHES No freshwater fishes have taken up residence irr the seas of Panama so far as the records show, and as the obverse side of the coin there is a group of freshwater fishes over the world which are extremely reluctant to enter salt water and are never found there (Myers 1938). Myers called them Primary freshwater fishes. A second group, which is made up of those species that occasionally are found in low-salinity waters and sometimes even higher, he called Secondary freshwater fishes. A third group, which may traverse the whole salinity gradient for various reasons, are called Periph- eral freshwater fishes. They were originally named by Nichols (1928) who recognized that most of them were of marine affinity. These terms have been adopted by recent students of ichthyogeography (cf. Loftin 1965; Miller 1966). Isthmus America, as a mid-Pliocene uplift, ranged from Tehuantepec, Mexico, to and including the coastal plain of Colombia, so that the southern part formed a little cap of northern South America. After this connection took place the freshwater fishes and other animals from both continents began to move up and down the isthmus. Older zoogeog- raphers held that most fauna moved from north to south, but as Myers (1938) pointed out, “There is not a scrap of factual evidence . . . on which to postulate a North American origin of the present South American fresh water fishes.” Myers (1938) goes on to say that one characin and one cichlid of the South American fishes have reached Texas. Of the six families of common North American fishes, the ♦Some purists would use “salt water" only for artificial brine mixtures and reserve “sea water" only for the oceans. However, there are too many "Old Salts” who have used "salt water” for seawater, or even for th»' sea itself, for such achange to come now. Marine Fishes of Panama as Related to the Canal 269 four main ones (perches, darters, sunfishes and minnows) have not penetrated Isthmus America and only two suckers and one North American catfish are found below Tehuan- tepec. The Poeciliidae may be autochthonous to Isthmus America and specifically to the Yucatan land mass (Myers 1938; Miller 1966). The freshwater fishes of Panama were first extensively studied by Meek and Hildebrand (1916). They listed 94 species of Primary and Secondary freshwater fishes and marine recent invaders, Meek and Hildebrand (1916, p, 233) stated that “the fish fauna of Panama is essentially that of South America and most of the forms seem to have entered from that direction.” Myers (1938, p. 343) has pointed out that “throughout the world the migrations of fresh-water fishes over extensive continental areas have been excessively slower than those of almost any creature that can creep, crawl, walk or fly, however closely that creature may have been bound by its ecological tolerance.” And he stated that this is nowhere better illustrated than in Isthmus America. If the ancestors of the characin and cichlid fishes now found in Texas and New Mexico left South America soon after the isthmus formed, they traveled at a rate of 1 mile in 475 years, 1 1.10 feet in a year or 0.365 inch (0.9266 cm) per day. This assumes a distance of 3,000 miles and a time span of 5.7 million years. Even if they started only a million years ago the speed of travel has been quite slow. The reasons for this slow spread of the freshwater fishes are obvious. Isthmus America is mostly a ridged, mountain- ous strip of land with sleep profiles and mostly short, small rivers. The river basins are small. In turn the estuaries are small and virtually nonexistent, especially in the dry season, Bcaler (1947) made the statement that in Panama, 475 streams empty directly into the oceans. For that reason the abundant characins and neotropical catfishes in Panama, “a vanguard from the south of the great Amazonian fauna,” (Miller 1966) cannot work their way along the sea shores. Even most Secondary fishes are precluded by full sea water and euryhaline groups, such as the Cyprinodontes, are shelter seekers and they do not roam the open beaches far from river mouths and estuaries. Gunter (1945) found only three on the sea beach among 9,010 specimens of six eury- haline species of cyprinodontoids in Texas waters, and these were near the passes to inside waters. Simpson and Gunter (1956), in a study of Texas coastal cyprinodontoids, set up no stations on the open sea beach because experience had shown that it was no place to catch these fishes. Gunter ( 1 957) reported one Cyprinodon variegatus and 1 2 Fundulus similis on open beaches among 10,633 other fishes. A few yards away at nearby stations in the passes 584 of the two species were caught. The numerous small river basins of Panama are well separated by steep ridges. There are 32 of these. In general the gradient is steep and the rivers are short. The Rio Bayano, the largest, is less than 100 miles in extent and many rivers are less than 10 miles long. The average length seems to be about 30 miles. During the dry season many of the smaller streams almost go dry, while in the rainy season they become torrents, and rises in height of 20 feet in an hour’s time sometimes take place. These accounts are taken from Meek and Hildebrand (1916) and Loflin (1965), who have been chief ichthyological explorers. According to Loftin (1965, p. 8), “Panama^ system of drainages may be summed up as follows: a large number of short, steep isolated streams with small watersheds, which course rather directly down from the mountains to empty separately into the sea. This feature may be the single most important limiting factor in the dispersal of freshwater fishes in Panama.” The 32 basins in the 29,000-square-mile area average about 906 square miles in extent, The dividing spine gener- ally runs closest to the Atlantic, except near the Canal, and the Chagres River Basin of the Atlantic side is the largest, but one of the lowest in average altitude. Half of the area of the country is above 1,000 feet in altitude with some peaks of 1 1,000 feet. These basins are almost as isolated as so many tropical islands at sea, and they have both a higher percentage of marine fishes in their streams and a rather sparse fauna withal. Tire Panamanian river basins have an insular aspect. The Canal connects or runs through only three river basins, the Chagres on the Atlantic and the (wo small basins between the Rio La Capita and Rio Bayano on the Pacific. Only the Chagres connects with the Canal and fish going from one basin to the other would have to go by way of the oceans, which is highly improbable, due to the reluctance of Primary fishes to enter even oligohaline salt water. In any case, no such instance has been noted. Even so, such a case would have probably caused less disturbance than the introduction of the Peacock Cichlasoma from Colombia into Gatun Lake did. The lake fishes have not been studied per se, but they are remnants of the riverine ichthyofauna of the Chagres River reported by Meek and Hildebrand (1916) and corroborated by Loftin (1965), species by species. Insofar as there were no natural lakes in all of Panama until the Canal was dug, it would seem that these fishes have been under some stress in the lacustrine environ- ment. The Peacock cichlid is a predator on the other fishes and is now bringing other pressures. It grows to a large size, 20 to 30 pounds, takes the hook avidly one-by-one from a school and is a fine food fish. However, these attri- butes to not arouse great enthusiasm among Latin Americans. In any case, it maybe assumed that there will be no passageway problems with freshwater fishes. Hildebrand (1939) said the freshwater fishes seemed to avoid the Canal, but, so far as his data went, this applied to the locks them- selves and not the cut or the channel through the lake. This means that these fishes avoid salt water even in its dilute concentrations. 270 GUNTER THE PANAMA CANAL AS RELATED TO FISHES The Canal runs from Limon Bay on the Caribbean Sea at Cristobal on the northern side to Balboa on Panama Bay of the Pacific Ocean. The course is almost due south for 6.5 miles to Gatun Lock which lifts ships 85 feet up in three stages to Gatun Lake. This lake was formed by damming the Chagres River and covers 164 square miles with depths up to 85 feet. The southward course of the channel continues on in the lake for another 5 miles and then goes directly cast. From that point on, there are over 600 cumulative degrees of turns before it reaches the southern terminal of the Bay of Panama, but all are generally southeast. From Gatun, the channel goes through Gaillard Cut to Pedro Miguel Lock, which lowers the ships 31 feet to Miraflores Lake. One mile farther on are the Miraflores Locks, which lower ships 54 feet back to sea level. The Canal channel is 50 miles long from ocean to ocean. The isthmus is 40.27 miles wide at this point. There are six pairs of locks all 1,000 feet long and 1 10 feet wide, with walls of 81 and 82 feet high. It takes 7 hours for a ship to pass through. A ship coming through from the north travels through salt water from Limon Bay to the lock at Gatun Lake where it is raised into freshwater. From there through Gatun Lake, Gaillard Cut and the Pedro Miguel Locks, the ship is in fresh wafer. In Miraflores Lake, the water is lightly brackish from the Miraflores Locks when the traffic is heavy. In summary, a ship or Fish following the same path would travel through 6 or 7 miles of sea and brackish water to Gatun Lake, 37 miles of fresh water through the lake, 2 miles of slightly brackish water in Miraflores Lake and 4 miles of brackish water to sea water at Balboa. There is no physical barrier to the crossing of the isthmus by a fish, as Hildebrand (1937) has stated. In this connection one should refer to Corps of Engineers reports (1956) and Hall (1956) concerning the locking of mullet ( Mugil ceph- alus ) from the St. Lucie Canal into the St. Lucie River when they were coming out of Lake Okeechobee, Florida. The Corps of Engineers found that it was much simpler to do this than to let the Fish stack up and Finally die in large masses at the locks while waiting to get back to sea. Hildebrand (1939) presented a table from data collected over an unknown number of years by Panama Canal officials, which shows that the salinities at the “Inner Harbor” at both ends of the Canal ranged from 16.0 to 20.0 °/oo saline. In Miraflores Lake it was 0.1 to 3.07oo and in Galun Lake it was 0,005 to Q.02°/oo (5 to 20 parts per million) or very soft fresh water. Menzies (1968) towed animals through the Canal and reported a salinity of 25.5°/oo in one of the Miraflores Locks, 1 .0 in Miraflores Lake, 0.0 in Pedro Miguel Lock and Gatun Lake and 23,5 in one Gatun Lock. Neither time, place, method of salinity determination or depth was given by Menzies. Abele (1972) found the salinity from top to bottom of the Pedro Miguel Locks to be 0.0 to 0.4% o , with an accuracy of 0.5%©. Jones and Dawson (1973) took salinities and temperatures at 2-meter intervals from top to bottom at 19 to 22 stations from the Bay of Panama to Limon Bay April 13-May 1 , and November 6-15, 1972, at the end of the dry and wet seasons, respectively. Those authors found that in the locks the water was very homogenous from top to bottom. At the end of the dry season the salinities were near 30.0°/oo in the lower Mira- flores Locks, 4.0 to 6.0 in the upper and 1 .0 to fresh from Miraflores Lake to Middle Gatun Lock. In the lowest lock, Gatun Lock, the highest salinity was 15,0% o . At the end of the dry season Miraflores Lake and the Middle Gatun Lock were salty, while the intervening areas were fresh. Essentially these reports all agree that from Pedro Miguel Lock to upper Gatun Lock, inclusive, the water is fresh even in the dry season. THE CANAL AS A PASSAGEWAY FOR FISHES Hildebrand (1937) showed that the euryhaline tarpon Megalops atlanticus (Valenciennes) had crossed the Canal to the Pacific and they are still reported there from time to time, but ichthyologists fail to catch them in their infinitely miniscule collections and doubt that they have established breeding populations there (Bayer et aJ. 1970; McCosker and Dawson 1975). In fact it would be quite unexpected for this warm-water, estuarine-loving species to expand quickly along the shores of Pacific America. Recent sports Fishing reports with pictures show the fish to be now 150 miles from Balboa. In addition to the tarpon, McCosker and Dawson (1975) list the following Fishes as having crossed the isthmus by way of the Canal: Atlantic to the Pacific Oostethus lineatus (Valenciennes). This is a completely euryhaline pipefish and breeds in both fresh and salt water as does Syngnathus scovelli on the United States Gulf coast (Whatley 1962), Lophogobius cyprinoides (Pallas). This fish has been found in the Third Lock Lake but a significant meristic difference between this and the Atlantic populations has been reported. However, there is no proof that it has reached the Pacific. Barbulifer ceuthoecus (Jordan and Gilbert). This species was collected in Panama Bay but it is said to not be eury- haline and may have “crossed” in water ballast. Lupinoblennius dispar Herre. Found only in Miraflores Lock, not in the Pacific. Hypleurochilus aequipinnis (Gunther). A breeding popu- lation was found in Miraflores Lock, but is was not taken in the Pacific. Marine Fishes of Panama as Related to the Canal 271 Pacific to Atlantic Gnaihonodon speciosus (Forsskal). This Fish has been taken from the lower Gatun Lock but has never been seen in the Atlantic. Ombranchus punctatus (Valenciennes). This Indo-Pacific goby has been found in Limon Bay. It is also found in Trin- idad and Venezuela. Possibly it has been there for ages. Gobiosoma nudum (Meek and Hildebrand). This goby was reported from Galeta Reef (Atlantic) one time. Of the eight above species listed by McCosker and Daw- son (1975) under the headings, “Marine Fish Migrants, Atlantic to Pacific,” and “Pacific to Atlantic,” there is one large fish, a carangid; one pipefish; three blennies and three gobies. Of these the pipefish Oostethus Uneatus and the gobies Ombranchus punctatus, Gobiosoma nudum and Barbulifer ceuthoecus, have been found in the other ocean. The pipefish seems to be an authentic migrant to the Pacific. The goby Ombranchus punctatus could have scarcely spread from Limon Bay to Trinidad and Venezuela since the Canal was opened and the most reasonable conclusion is that it has been a resident of both coasts for a long time. The goby Barbulifer ceuthoecus is admittedly stcnohaline and came in ballast. Gobiosoma nudum seems to be an actual migrant across the isthmus. Thus the tarpon, the pipefish and one goby are indubitable migrants across the isthmus by way of the Canal. At this rate it will take the 66 euryhaline fishes of Panama waters, according to Miller’s (1966) count, a matter of 1 ,950 years to cross the Canal as it is now constituted. McCosker and Dawson (1975) accept all putative canal crossers as crossers. For that reason they agree, although reluctantly it seems, with the conclusions of Bayer et al. (1970) that “there is no evidence to suggest any exchange of reef fishes through the present canal” and “current exchanges involve estuarine fishes, primarily gobies and fishes that can live among the fouling organisms on the hulls of ships.” However, the collections by these workers were made so far out on the Continental Shelf that the collections shed no light on the question of migration across the isthmus; and if the conclusions are correct, they derive from the prescience of experienced biologists and not from any particular data presented. However, Hildebrand adduced information somewhat contrary to those conclusions. Hildebrand (1937) previously gave evidence that the tarpon had crossed the isthmus and he gave more in 1939. He also said that Anchovia parva Meek and Hildebrand had crossed the freshwater barrier to the lower Miraflores Lock on the Pacific side. Remarkably enough he also reported the spotted jewfish, Promicrops itaiara (Lichtenstein), of the Atlantic from the lower Miraflores Lock. The fish weighed 47 pounds. These last two species are certainly putative crossers. Significantly, Hildebrand’s records and pictures show that several species and families of large fishes enter the locks, for example, the carangids or jacks, snooks, seabasses, groupers, snappers, grunts and sciaenids. These are not small blennies or gobies skulking in the fouling mats. Large fish can go through if they can pass the freshwater barrier. Gunter (1942) listed nine fishes from Panama that were fully euryhaline. On that list Oostethus lineatus was listed as only a “probable euryhaline.” Meek and Hildebrand (1923) reported it as breeding in the fresh water of Gatun Lake. In all, there are four fishes that have made indubitable crossings of the present Canal and gotten free of man’s works. Only one, the tarpon, is a large fish. The other three are the pipefish Oostethus lineatus\ a noncuryhaline goby, Barbulifer ceuthoecus, which evidently was carried by ship; and Gobiosoma nudum , the naked goby. Additionally there are putatives, probables and possibles, numbering some 15 or so fishes, if circumtropical species are included, such as Caranx hippos , Mugil cephalus and M. curema. If such species do cross it would be difficult to prove unless they were tagged. This means that no effect of their crossing can be detected, even though they have been separated at least 5 million years and the Pacific jack was considered to be a different fish, Caranx caninus, until recently. It is significant that both Hildebrand( 1939) and McCosker and Dawson (1975) thought that they found evidences of hybridization in the gobies taken within the Canal. The projected use of the Canal shows that in the year 2000 and thereabout the Canal traffic will use up in about a month’s time the 22 billion cubic feet of water held in Gatun Lake as a reserve. Back pumping has been suggested as a way out of this dilemna and it will no doubt suffice. The objection has been raised that this action will increase the salinity to such an extent that it will cause Gatun Lake and the Canal to become a greatly used thoroughfare for the fishes and even the sea snakes from the Pacific side. The comments especially from various ichthyologists say that this action would be “unwise,” “irresponsible,” “indefen- sible,” “dangerous,” etc. Such terms are not science and in fact are those that can be heard in adversary court trials any day. One report has even suggested that there will be some sort of change in the germ plasm so that the invaders will exert some sort of overwhelming dominance over the indigenous biota. We may wonder on this basis what evolu- tionary horrors were caused by freeflowing and commingling oceans in the days before the isthmus became a complete barrier. With regard to the salinity and what will happen when and if Gatun Lake attains a salinity of 5.0°/oo, which the engineers say is the most likely equilibrium to be attained by back pumping, there is not a great deal of information available. However, Gunter (1945) found that at the salinity range of between 0.0 and 5.0°/oo in Texas waters, the number of species of fishes was about one-half of those recorded at salinities of 30.0°/oo and above. Most of these were predominantly small and young specimens. Thus, 272 Gunter Gatun Lake might be expected to assume characteristics of a very low-salinity estuary so far as the marine fishes are concerned* It would also retain a good bit of its freshwater fauna while losing some of it. Myers ( 1 949) was troubled about his category of Primary fishes because some of them have been found capable of tolerating high salinity, if acclimated gradually under experi- mental conditions. The salinity of a freshwater fish’s blood is equal approximately to one-third sea water and at any salinity below 12.0%* it maintains the hyperosmotic rela- tionship of a freshwater fish to the salinity of the water. Some freshwater fishes live in quite highly saline lakes in the United States and hopefully the fishes of Gatun Lake would not be greatly disturbed by the slow increase of salinity to 5.0%*. The efficiency of the Canal as a passageway for fishes between the oceans would be indubitably increased by back pumping. In terms of proportions of the salinity change, some 30 species of fishes would be expected to make the crossing. Presumably these would be the snooks, jacks, mullets, snappers, gobies and other fishes now known to be euryhaline and semi-euryhaline in this region. As a result, there would be a change in competition in habitat niches, in interbreeding, in food chains and some change in gene flow, population genetics and general competition. In summary, the same old evolutionary panorama that goes on at all times in all oceans would be changed somewhat by back pumping, but not in any way that could be called unnatural. These changes would be hard to detect and hard to follow except for the presence of different species in an area where they were not known before. There is no reason to expect that these biological processes will fail to take place, or will change in any way to make them more or less strenuous, more or less wasteful of basic energy processes, or change in any way which can be objectively described as harmful, unless perhaps someone prefers one goby to another. Even so, these people can scarcely suffer over the preferred one’s demise over a period of 500 to 1 ,000 years, which would probably be the time required. The same general situation will hold true for a sea level canal. REFERENCES CITED Abele, L. G. 1972. Introductions of two fresh water decapod crusta- ceans (Hyrrenosomatidae and Atylidae) into North and Central America. Crustaceana 23:209-218. Anderson, William W. & JackW.Gehringer.1965. Biological-statistical census of the species entering fisheries in the Cape Canaveral area. U.S. Fish Wild l . Sery. Spec, Sci Rep. Fish. No 514. 79 pp. Bayei, F. M.. G. L. Voss & C. R. Robins. 1970. Biocnvironmental and radiological safety feasibility studies - Atlantic-Pacific Intcr- oceanic Canal. Report on the marine fauna and benthic shelf- slope communities of the isthmian region. Miami: University of Miami. Rosenstiel School of Marine and Atmospheric Science. 311 pp. Bealer, L. W, 1947. Panama. Encyclopaedia Britannica 17 :1 68-170. Corps of Engineers, U.S. Atmy, Jacksonville, Florida. 1956. Central and southern Florida project for flood control and other pur- poses. Part IV. Lake Okeechobee and outlets. Supplement 5. Special report on mullet migrations through St. Lucie Lock and Dam, 1955-56. 15 pp. Dengo, G. 197 3 . Estructura Geologica, Historia Tecionica y Morfo- logia de America Central. 2nd ed. Central Regional dc Ayuda Tecnica, A.I.D., Mexico. Emiliani, C., S, Gaeitner & B. Udz. 1972, Neogene sedimentation on the Blake Plateau and the emergence of the Central American isthmus. Palaeogeogr . , Palacoclima td. , Palaeoecol. 11*1-10, Eskinazi de Oliveira, Aida Maria. 1972. Peixes estuarinos do nordeste oriental Brasileiro. Arq. Cienc. Mar. 1 2(1 )i 35 — 41. . 1974. Ictiofauna das aguas estuarinas do Rio Pamaiba (Brasil). Arq. Cienc. Mar. 14( I ):4 1 —45. Gunter, Gordon. 1938a. The relative numbers of species of marine fish on the.Lnuistana Coast. Am. Nat. 72:77-83. . 1938b. Seasonal variations in abundance of certain estuarine and marine fishes in Louisiana, with particular reference to life histories. Ecol. Monogr . 8:31 3 346. 1941. Relative numbers of shallow water fishes of the northern Gulf of Mexico, with some records of rare fishes from the Texas coast. Am. Midi Nat. 26(l):l94-200. . 1942. A list of the fishes of the mainland of North and Middle America recorded from both freshwater and sea water. Am. Midi. Nat. 28(2):205-326. . 1945. Studies on marine fishes of Texas. Publ Inst. Mar. Sci. Univ. Tex. l(l):l -190. _____ , 1956. A revised list of euryhaline fishes of North and Middle America. Am. Midi. Nat. 56(2):345— 354. . 1957. Predominance of the young among marine fishes found in fresh water. Copeia 1 957(1 ): 1 3— 1 6. Hall, Gordon E. 1956. Mullet madness. Fla. Wildl. (October): 12, 41 42. Hildebrand. S. F. 1937. The tarpon in the Panama Canal. Sci. Mon. N Y. 44:245-246. . 1939. The Panama Canal as a passageway for fishes, with lists and remarks on the fishes and invertebrates observed. Zoologica (N.Y.) 24(3):15-45. Jones, M. L. & C. E. Dawson. 1973. Salinity-temperature profiles in the Panama Canal locks. Mar. Biol. 21 :86-90. Loftin, Horace Greeley. 1965. The geographical distribution of freshwater fishes in Panama. Ph.D. thesis, Florida State Univer- sity, Tallahassee, Florida, 264 pp. McCosker, J, E. & C. E. Dawson, 1975. Biotic passage through the Panama Canal, with particular reference to fishes. Mar. Biol. 30:343-351. Meek, Seth E. & Samuel F. Hildebrand. 1916. The Fishes of the Fresh Waters of Panama. Field Museum of Natural History, Chicago, Illinois. 371 pp, & . 1923. The Marine Fishes of Panama. Field Museum of Natural History, Chicago, Illinois. Part 1, Publ. No. 215, Zoological Series, Vol. XV. pp. 1-330. & . 1925. The Marine Fishes of Panama. Field Museum of Natural History, Chicago, Illinois. Part 2, Publ. No. 226, Zoological Series, Vol. XV. ppT 331-707. & . 1928. The Marine Pishes of Panama. Field Museum of Natural History, Chicago, Illinois. Part 3, Publ. No. 249, Zoological Series, Vol, XV. pp. 709 1045. Menzies, R J. 1968. Transport of marine life between oceans through the Panama Canal. Nature (Land) 220(5169):802-803. Miller, R. R. 1966. Geographical distribution of Central American freshwater fishes. Copeia 1 966(4 ):77 1 -810. Marine Fishes of Panama as Related to the Canal 273 Myers, G. S. 1 938. Fresh-water fishes and West Indian zoogeography. Ann. Rep. Smithson. Inst. 1937:339-364. . 1949. Salt-tolerance of fresh-water fish groups in relation to zoogeographical problems. Bijdr. Dierkd. 28:315-322. Nichols, J. T. 1928. Fishes from the White Nile collected by the Taylor expedition of 3 927; a discussion of the fresh-water fish faunae of Africa. Am. Mus, Novit. No. 319, 7 pp. Price, J. B. & Gordon Gunter. 1964. Studies of the chemistry of fresh and low salinity waters in Mississippi and the boundary between fresh and brackish water. Int. Rev. Gesamten Hydrobiol. 49(4):629-636. Raven, Peter H. & Daniel L Axelrod. 1975. History of the flora and fauna of Latin America. Am. Sci. 63(4):420-429. Rosenblatt, R. H. 1967. The zoogeographic relationships of the marine shore fishes of tropical America. Stud, Trop. Oceanogr. (Miami) 5:579-592. Simpson, Don G. & Gordon Gunter. 1956. Notes on habitats, syste- matic characters and life histories of Texas salt water Cyprino- dontes. Tulane Stud. Zool. 4(4): 11 5- 134. Whatley, E. C. 1962. Occurrence of breeding Gulf pipefish, Syn- gnathus scovelli, in the inland fresh waters of Louisiana. Copeia 1962(1):220. Gulf Research Reports Volume 6 | Issue 3 January 1979 A Filamentous Bacterium on the Brine Shrimp and Its Control Mobashir A. Solangi Gulf Coast Research Laboratory Robin M. Overstreet Gulf Coast Research Laboratory Ann L. Gannam Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.08 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Solangi, M. A., R. M. Overstreet and A. L. Gannam. 1979. A Filamentous Bacterium on the Brine Shrimp and Its Control. Gulf Research Reports 6 (3): 275-281. Retrieved from http:// aquila.usm.edu/gcr /vol6/iss3/8 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua. Cromwell(2)usm.edu. Gulf Research Reports , Vol. 6, No. 3, 275-281, 1979. A FILAMENTOUS BACTERIUM ON THE BRINE SHRIMP AND ITS CONTROL 1 MOBASHIR A. SOLANGI, ROBIN M. OVERSTREET AND ANN L. GANNAM Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ABSTRACT A strain of a colorless, filamentous bacterium (tentatively identified as Leucothrb t rnucor) heavily infests the brine shrimp, Artemia salina. Its uitrastructure, unlike that of some other strains, does not reveal a distinct middle layer between its outer cell wall layer and cytoplasmic membrane, irregular blebs extending from the cell layers, or an external sheath. An entire infestation, represented as a mat of the bacterium with associated debris and microorganisms, sloughs from the shrimp when exposed to a variety of treatments. Primarily because most effective treatments are toxic to the shrimp, 100 ppm teiramycin provides the treatment of choice. INTRODUCTION A bacterium, tentatively identified as a strain of Leucothrix mucor, infested 100% of the adult brine shrimp, Artemia salina, in a 200-liter intensive culture tank. These heavily infested shrimp died at a faster rate than the stock could be replaced by maturing individuals. Death, however, did not appear to occur rapidly upon infestation. Because of ihe vulnerability of the shrimp to the bacterium, the known pathogenic effect of I. mucor on many crustacean larvae and eggs confined in rearing facilities (e.g., Nilson et al. 1975, Lightner 1975), and the potential to contam- inate larval crustaceans by feeding them brine shrimp, we tested a variety of treatments on infested individuals. Also, because of the large number of poorly characterized strains of L, mucor , we present some morphological data on the form we encountered. MATERIALS AND METHODS Infested Artemia salina were obtained from the Oyster Biology Section of the Gulf Coast Research Laboratory. Brine shrimp eggs, presumably uninfested, came from San Francisco Bay ponds and the hatched shrimp were main- tained in salinities of 45 to 50 parts per thousand (ppt) at 23 to 25°C with whole wheat flour; adults averaged 1 1 mm in total length. In order to identify the bacterium, we observed it with a Nomarski differential interference contrast and an electron microscope, studied it histologically, and cultured it using the methods of Pringsheim (1957). A few heavily infested brine shrimp were embedded in paraffin and sectioned at 6 to 7 pm, and the sections were stained using Harris' hema- toxylin and eosin stain, Bennhold’s method lor amyloid, McManus’ method for glycogen (PAS), and alcian blue ! This study was conducted ip cooperation with the U.S. Depart- ment of Commerce, NQAA, National Marine Fisheries Service, under PL 88-309, Project Nos. 2-262-R and 2-325-R. Manuscript received July 27, 1 979; accepted August 1 3, 1 979. method for mucosubstances (Luna 1968). Additional material was fixed in 3% glutar aldehyde, post-fixed in osmium tetroxide, embedded in Spurr’s embedding medium, sectioned on an LKB ultratome, stained with uranyl acetate and lead citrate, and photographed with a Siemens Elmiskop 1A electron microscope. Infested shrimp in groups of about 15 individuals were placed in glass bowls each containing 70 ml of artificial seawater (50 ppt, Rila Marine Mix) at 24±1°C. Diseased shrimp were exposed to the various chemicals listed in Table 1 . All tests were conducted in duplicate or triplicate, usually for periods of time commonly used for each type of treatment. When treatments lasted 48 hours, saltwater and chemicals were replaced after 24 hours. Experimental hosts were not fed while tested, and we defined cure as the absence of bacterial filaments. RESULTS Bacterium The colorless, filamentous bacterium attached its PAS- and congo red-positive holdfast to the gills, swimming appendages, antennae, and all other external surfaces of the shrimp’s adult and late instar stages. The site of attach- ment stained purplish-red to purple using McManus’ method and predominately blue using the alcian blue method. A loose mesh of bacterial filaments helped trap and support considerable debris and a variety of unidentified micro- organisms (Figures 1—4). Rosettes of filaments occurred commonly (Figure 5). Some infested appendages exhibited extensive deterioration, but the histological relationship between the bacterium and those lesions was not critically examined. Most attached filaments did not appear to penetrate deeply into the cuticle, and we never observed filaments extending through the cuticle or within a host. Filaments varied in appearance. Most typically contained refractive granules (Figure 4); however, many filaments had few or no granulated segments. We did not analyze the chemical composition of these granules. Widths of 50 typical 275 276 SOLANGI ET AL. TABLE 1. Treatments tested for controlling infestations of Leucothrix mucor on adult brine shrimp. Treatment Number of shrimp Number of replicates Concentration 1 Exposure-period in hours Average percentage cured ± SE Average percentage died ± SE Control 152 9 48 25.5 ±2.5 34.2 + 6.9 Formalin 46 3 40 ppm 12 58.7 ±5.2 21.7+7.3 Potassium permanganate 45 3 10 ppm 1 44.4 ±4.7 20.0 ±3.1 Nitrofurazone 2 46 3 100 ppm 6 47.8 ±3.8 10.8 ± 2.8 Cu trine 3 45 3 100 ppm 4 60.8 ±3.2 15.2 ±1.4 Cutrine 45 3 100 ppm 48 28.8 ±6.5 53.3 ±3.9 Cutrine 45 3 0.5 ppm 4 51.1 ±1.8 20.0 ±3.1 Cutrine 47 3 0.5 ppm 48 48.2 ±7.3 48.9 + 8.8 Terramycin 4 78 5 10 ppm 48 37.1+5.5 38.4 ±3.1 Terramycin 77 5 50 ppm 48 45.4+7.2 36.3 ±6.7 Terramycin 74 5 100 ppm 48 67.5 ±8.1 25.6 + 4.6 Terramycin 84 5 200 PPm 48 51.1 ±2.2 21.4 ±6.1 Terramycin 16 1 200 ppm 1 43.8 12.5 Salinity reduction 5 47 3 10 ppt 48 72.3 ±9.3 19.1 ±8.8 Freshwater 15 1 0 ppt 1 40.0 33.3 1 Based on commercial preparations and not active ingredients 2 5-nitio-2-furaldehyde semicarbazone 3 Copper sulfate + triethanolamine and other additives 4 4-(Dithethylamino)-l ,4 ,43,5,58,6,1 1 ,12a-octahydro-3,5,6,10,l 2,12a-hexahydroxy-6-methyl-l ,ll-dioxo-2-nephthacenecarboxamide 5 Produced with Rila Marine Mix filaments from three shrimp ranged between 1 and 2 jum. Cells near the base of the filaments averaged 2.3 urn (1.0 to 2.9 jum) long by 1.8 n m (1.5 to 2.0 /rm) wide, those near the middle were 1.6 by 1.6 jum, and those near the apex, 2.2 by 1.0 gm. Twenty nOngranulated cells near the middle of a filament averaged 2.4 by 1.3 pm. Examination of the filament’s ultraslructure revealed fibrillar nuclear material, storage granules, and ribosomes dispersed in the cytoplasmic matrix. /Ml those features (Figures 6—11) are considered typical components of L. mucor in its broad sense, except for an aspect presented in Figure 8 and mentioned below. The outer wall layer and the cytoplasmic membrane were both simple and smooth. Each was about 1 1 nm wide with the total wall about 45 to 5 5 nm wide. Some filaments appear similar except the cells obtain a length as long as ten times the width. Figure 8 illustrates the variation in length between adjacent cells of these fila- ments. The long cell length is not typical of /,. mucor, and the organism probably represents a strain or species distinct from the dominant organism of our study. The cuticle at the site where L. mucor attached (Figure 7) was altered and notably rougher than the smooth adjacent cuticle. No significant underlying cellular damage was apparent, even though slight penetration of the holdfast occurred within the cuticle. The second cell in the middle filament of the rosette in Figure 7 represents one of several similar examples observed ; it differed from the others shown by having more granules and a large, central, irregularly shaped, compact structure. The cell is possibly a reproductive cell; however, we do not discount the possibility of a normal cell undergoing degeneration. Nauplii had no conspicuous infestations, whereas juveniles at about the sixth instar, the stage when the rate of molting frequency decreases, possessed numerous short filaments, both isolated and in rosettes. A moderately heavy infestation was conspicuous when comparing an infested host with a noninfested shrimp (Figures 9-10). The entire bacterial mass sloughed from treated individuals (Figure 1 1). In a single attempt to culture our material, no more than eight cells developed in a chain. Numerous spherical cells, presumably gonidia, glided about on our “slide cultures.” Filaments could not be demonstrated from liquid media when kept stationary or shaken or from a streaked agar plate. Treatment The average percentage per replicate of adult brine shrimp having sloughed bacterial mats and remaining free of I,, mucor after exposure to a variety of treatments is listed in Table 1. Moderate variations in results for each concentration occurred among replicates. All treatments indicated some success for cure, but for reasons presented in the discussion I Figures 1-5. Leucothrix mucor on brine shrimp. (1) Moderate infestation showing abundant debris. (2) Close-up of setae showing attached bacterial colonies. (3) Close-up of debris and microorganisms. (4) High-power view of filaments showing granules. (5) Rosettes on brine shrimp seta. 278 SOLANGI ET AL. Figuies 6 -8. Election micrographs of filamentous organisms on brine shrimp. (6) Typical cells comprising a filament of Leucolhrix mucor, x 32,800. (7) Holdfast attachment site for a rosette of Leucothrix mucor, x 29,300. Note assumed reproductive cell situated as second cell in middle filament. (8) Filament with some elongated cells, probably not Leucothrix mucor, x 16,100. Filamentous Bacterium on Brine Shrimp 279 Figures 9—11. Photomicrographs of control shrimp and infestation of Leucothrix mucor. (9) Noninfested brine shrimp. (10) Brine shrimp moderately infested. (1 1) Sloughed mat and associated debris. and in Table 1 , treatment with 100 ppm terramycin seemed most practical. DISCUSSION Leucothrix mucor comprises a variety of over 30 strains (Raj 1977). Characterizations of these strains based on the combination of morphological features, biochemical assess- ments, and culturing ability arc known for only a few. Because identification of our material is not positive and variations among strains are considerable, we tentatively consider our strain one of L. mucor. Some strains of L. mucor differ in many respects from the one we report. Ours from the shrimp fits no clearly defined assemblage of characteristics. It has no sheath-like layer around the cell wall such as that reported by Anderson and Hcffcrnan (1965), but neither do most strains. Brock and Conti (1969) showed irregularities and bleb-like exten- sions from the cell layers and a well-formed, thin, single- membrane, or middle layer (pcptidoglycan), between the inner and outer double membranes, whereas the present form has relatively smooth membranes and no distinct middle layer. Abundant rosettes, such as those present on the brine shrimp, are not thought to be typical in rich nutritional regimes (Raj 1977). Sleenbergcn (San Diego State University, personal communication) has shown that a strain from the shrimp Pcnaeus californiensis has a uniquely different guanine-plus-cytosinc ratio of deoxyribonucleic acid along with a lack of antigenic similarity when compared to other isolates. Consequently, that strain may not be L. mucor. The electrophoretic mobilities of enzymes were not studied in our material, but Kelly and Brock (1969) have shown significant differences in mobilities of two dehydrogenases from different strains. Strains also differ in their tolerance to salinity. The status of the one or more species of ' ihiothrix , which closely resemble L. mucor . also remains uncertain because these anaerobic forms containing sulfur granules have not been consistently cultured. The composition of granules in our aerobic material was not analyzed, but their presence was inconsistent. Some filaments had them and others did not; moreover, a filament occasionally consisted of cells both with and without granules. Filaments from moribund shrimp, following three days of a gradual reduction in salinity, also possessed cells with and without granules, in any event, the presence and absence of granules did not provide evidence indicating the existence of two separate species or strains. The holdfast did not spread out over the host's cuticle nor did it penetrate extensively. Couch (1978) suggested that the assumed mucoid substance of this holdfast might coat the gills of penaeid shrimp and block gas diffusion. We found that the cuticle became deformed at the attach- ment site. The holdfast of a strain of L. mucor on the peritrich Zoothamtlium sp. infesting the gills of penaeid shrimp has been observed by Foster et al.( 1978) to penetrate the stalk of the ciliate and to spread out into the extracellular fibrillar matrix. Leucothrix mucor , on occasion, probably penetrates several organisms or their products. It entangled the ciliate h'pistylis sp. on fishes in low-salinity habitats (Overstreet and Howse 1977), but the filamentous organism (0.3 jam wide) within the stalk was definitely not L. mucor as implied by those authors (in their Figure 31 ). In the natural environment, many crustaceans remain free of infestations by preening themselves. Bauer (1977) showed this by ablating the third maxillipeds of the shrimp lieptacarpus pictus so that it could not groom its antemiules. The antcnnules of these test individuals became heavily fouled with Leucothrix sp. Leucothrix mucor infests Artemia saline and many other crustaceans extensively when the medium is rich with nutrients. Consequently, rearing facilities foster infestations. According to J r A. Quick. Jr. (Dow Chemical Company, personal communication). L. mucor infests the shrimp only when the medium is enriched, even though shrimp popula- tions exceed 100 per liter. Consequently .when practicality prevents culturing crustaceans by decreasing the nutrient levels, treating the system with chemicals should be consid- ered. When contaminating rearing facilities, several strains of L . mucor can kill animals 11 hosts. Lightner el a!. (1975) postulated that heavy infestations on penaeid shrimps caused 280 SOLANGI ET AL. hypoxic conditions for the shrimp which thereby weakened or killed them, especially those shrimp moiling or already in low-oxygen conditions. In all the treatments tested (Table 1), the entire infesta- tion on an individual sloughed as one mat. A mat involving some append ages and setae can be seen in Figure 1 1 . Sloughed mats seemed to remain attached to a complete or partial molt involving the infested regions. Follow-up attempts to acquire mats for ultrastructural analysis of the holdfast and cuticle were unsuccessful. Such an investigation, however, seems desirable because sloughing often occurred within 1 to 2 hours after treatment. The 2-day treatment with 100 ppm terramycin seemed the most desirable. In fact, introduction of 100 ppm into the culture tank eliminated the organism permanently, suggesting that the drug killed the parasite. The only other reported use of terramycin in controlling L. mucor was by Sandiferand Smith (1976) who obtained inconsistent results using 1-hour dips of concentrations up to 30 ppm. Their strain infested reared juveniles of Macrabrachium rosenhergi (the Malaysian prawn) in salinities of 12 to 13 ppt. We found an increasing percentage of cured individuals and a decrease in mortality as wc increased the dose to 100 ppm. A concen- tration of 200 ppm produced results similar to those of 100 ppm. Treatments other than terramycin had a variety of draw- backs. Rapidly decreasing the salinity from 50 to 10 ppt was successful, but the shrimp cannot survive and reproduce in low-salinity conditions for extended periods. Conse- quently, bacteria in the system would presumably reinfect the shrimp if the salinity were increased or if the shrimp from water with high-salt content were removed, treated, and returned. Moreover, when gradually decreasing the salinity to 10 ppt over 48 hours, only 2 of 17 shrimp sloughed their bacterial mats. When under stress from many chemicals for time periods of various lengths, the brine shrimp is hardy. For example, specimens could withstand more than 10 minutes of 3% glutaraldehyde or 10% formalin and then live for at least 1 hour if transferred to normal sea water. On the other hand, even low concentrations of certain chemicals caused patho- logical responses in shrimp. Both potassium permanganate and formalin, used as indicated for treatments, caused shrimp to twirl, a continuous orbital movement from the surface to the bottom of the water column. Most host deaths caused by those compounds occurred during the first day, whereas those recorded in other treatments except Cutrine-plus® occurred gradually. Sandifer and Smith ( 1 976) noted heavy mortality of prawns with KMN0 4 for long and short exposures, and Lightner (1977) reported a potential for severe gill damage in penaeid shrimp following a 1-hour treatment of 10 ppm. In our material, we noted blackened gills. Twirling occurred in all treatments except terramycin, with that behavior most pronounced in high concentrations of cutrinc and least pronounced in nitrofurazone. Nitro- furazone appeared to be the second-best treatment, but was tested for 6 hours only and should be investigated further. The algacide Cutrine-plus (a chelated copper compound), while an effective drug for brine shrimp in a bath for up to 4 hours, caused many mortalities during 48-hour exposures, even at 0.5 ppm of the commercial product. In addition to twirling, those shrimp exposed to Cutrine-plus for less than 4 hours at 100 ppm also rotated in a spiral around their own axes. Lightner and Supplee (1976) also noted a toxic response by the California brown shrimp to that drug. In order for those authors to increase biomass and decrease mortality of that shrimp, they introduced 0.1 ppm Cutrine weekly for a 24-hour period in a flow-through system. A few other treatments have been tested with a variety of success (Lightner 1977, Sindermann 1977). ACKNOWLEDGMENTS We thank J. A. Quick, Jr. for allowing us to utilize some of his extensive knowledge on brine shrimp. David W. Cook provided culture media, Roswitha Buxton assisted with the superb electron micrographs and histochemical results, and John Ogle provided technical help. REFERENCES CITED Anderson, J. 1. W. & W. P. Heffernan. 1965. Isolation and character- ization of filterable marine bacteria./. Bacterial. 90:1713-1718. Bauer, R. T. 1977. Antifouling adaptations of marine shrimp (Crus- tacea: Decapoda: Caridea); functional morphology and adaptive significance of antennular preening of the third maxillipeds. Mar. Biol. 40(3):261 -276. Brock, T. D. & S. F. Conti. 1969. Electron microscope studies on Leucothrix mucor. Arch. Microbiol. 66:79-90. Couch, J. A. 1978. Diseases, parasites and toxic responses of com- mercial penaeid shrimps of the Gulf of Mexico and South Atlantic coasts of North America. U.S. Natl. Mar. Fish. Serv., Fish. Bull. 76(1):1 -44. Foster, C. A,, T. G. Sarphie & W. E. Hawkins. 1978. Fine structure of the peritrichous ectocommensal Zoothamnium sp,, with emphasis on its mode of attachment to penaeid shrimp. /. Fish Dis. 1(4): 321 -335. Kelly, M. T. & T. D. Brock. 1969. Molecular heterogenicity of isolates of the marine bacterium Leucothrix mucor. J. Bacteriol. 100(1):14-21. Lightner, D. V. 1975. Some potentially serious disease problems in the culture of penaeid shrimp in North America. Pp. 75-97 in Proceedings U S. -Japan Natural Resources Program, Symposium on Aquaculture Diseases . Tokyo. . 1977. Filamentous bacterial disease of shrimps. Pp. 31 - 35 in Disease Diagnosis and Control in North American Marine Aquaculture; Developments in Aquaculture and Fisheries Science Vol. 6. Elsevier Scientific, Amsterdam. , C. T. Fontaine & K. Hanks. 1975. Some forms of gill disease in penaeid shrimp. Pp. 347 365 in Proceedings, 6th Annual Workshop, World Mariculture Society. Seattle, Washington. Filamentous Bacterium on Brine Shrimp 281 & V. C. Supplee. 1976. A possible chemical control method for filamentous gill disease. Pp. 473-481 in Proceedings, 7th Annual Workshop, World Mariculture Society. San Diego, California. Luna, L. G. 1968. Manual of Histologic Staining Methods of the Armed Forces Institute of Pathology. 3rd edition. McGraw-Hill, New York. 258 pp. Nilson, E. H., W. S. Fisher & R. A. Shleser. 1975. Filamentous infest- ations observed on eggs and larvae of cultured crustaceans. Pp. 367-375 in Proceedings, 6th Annual Workshop, World Mari- culture Society. Seattle, Washington. Overstreet, R. M. & H. D. Howse. 1977. Some parasites and diseases of estuarine fishes in polluted habitats of Mississippi. Ann. N.Y . Acad. Sci. 298:427 -4 6 2. Pringsheim, E. G. 1957. Observations on Leucothrix mucor and Leucothrix cohaerens nov. sp. with a survey of colorless fila- mentous organisms. Bacteriol. Rev. 2 1 (2):69 — 8 1 . Raj, H. D. 1977 . Leucothrix. CRCCrit. Rev. Microbiol. 5:271-304. Sandifer, P. I. &. T. I. Smith. 1976. Experimental aquaculture of the Malaysian prawn, Macrobrachium rosenbergii (de Man), in South Carolina, U.S.A. Pp. 1-7 in FAO Technical Conference on Aquaculture. Kyoto, Japan. Sindermann, C. J. 1977. Filamentous bacterial infestation (Leuco- thrix). Pp. 85-88 in Disease Diagnosis and Control in North American Marine Aquaculture; Developments in Aquaculture and Fisheries Science Vol. 6. Elsevier Scientific, Amsterdam. Gulf Research Reports Volume 6 | Issue 3 January 1979 The Annual Flows of the Mississippi River Gordon Gunter Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.09 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Recommended Citation Gunter, G. 1979. The Annual Flows of the Mississippi River. Gulf Research Reports 6 (3): 283-290. Retrieved from http://aquila.usm.edu/gcr/vol6/iss3/9 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(S>usm.edu. Gulf Research Reports , Vol. 6, No. 3, 283-290, 1979. THE ANNUAL FLOWS OF THE MISSISSIPPI RIVER GORDON GUNTER 1 Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ABSTRACT The Mississippi River drains two thirds of the lower United States plus 13,000 square miles of Canada. When North America was being colonized by Europeans, the river overflowed its banks about once every 3 years and spread onto the floodplain, which today covers 34,600 square miles of the valley. A natural levee formed alongside the river where the silt was dropped when water left the channel; the levee now slopes away from the river at about 7 feet per mile. This high ground was settled first by the white man at New Orleans in 1717. The spring floods barely topped the natural levee and the original town was protected by a ring levee 3 feet high. As more overflow areas were cut off from the river, the levees increased in height to about 40 feet. The hydraulics of the river became better and today more water and silt flows out to sea. About three fourths of the floodplain is closed off from the river, but in 1882 and 1927, the river took that land hack, and in 1973 almost 60% of the 22-million-acre area was flooded. Nevertheless, there have been no levee breaks since the Corps of Engineers took over flood control in 1928. The mean flow of the river since 1900 has been 646,000 cubic feet per second (cfs) moment to moment. The mode, median, quartiles and dedies of annual flows are given, and the measurements of dispersion, the standard deviation and coefficient of variation are given. The Alchafalaya River distributary has increased considerably at the expense of the Mississippi River since 1858. During the flood year of 1973, the Atchafalaya carried 37% of the total flow. It is estimated that unless it is brought under control, in about 60 years the Atchafalaya will equal the Mississippi. Flood years are not especially associated and in several cases low flows and flood years are close together. Measurements of river flows before 1900 are unreliable or absent. Since then, however, careful measurements of the daily flows of both distributaries have been taken by the Corps of Engineers and used to compile mean flows in cfs by years. The data extend for a series of 79 years. They were furnished to the author by the New Orleans District of the Corps. These data were used for all calculations given here on flows. The lowest flow recorded for the Atchafalaya was 13,300 cfs on September 22, 1925. The lowest flow for the Mississippi was 75,000 cfs on November 4, 1939. The highest for the Atchafalaya was 781,000 cfs at Simmesport on May 12, 1973; the highest for the Mississippi was at Tarbert Landing on February 19, 1937, at 1,977,000 cfs. Subjectively described floods of 1782, 1828, and 1882 tie in with 1927 and 1973 as 50-year floods. The 1927 and 1973 floods were remarkably similar; the former was the larger. The largest known flow of the river is only 25% less than the maximum which meteorologists say could be generated. Presumably such a flood could be handled without catastrophe. INTRODUCTION The establishment of European civilization in North America may be looked upon as a long march across the continent as the people established settlements, clearings and highways, and undertook utilization of the natural resources. This process can be divided into three large under- takings which resulted in actual change of the physical land- scape. The first task was the clearing of the impenetrable eastern forest which was then crossed only by Indian trails. This magnificent area of climax forest was not felled by the lumbermen: instead it was cut and burned piecemeal to make clearings for the settlers. West of the Mississippi River, settlements involved the plowing of the prairie and the killing of the buffalo. These processes brought about destruc- tion of both the tall and short grass prairies. The introduc- tion of livestock and the activities of farming insured the 1 At various times between 1938 and 1979, the writer has been an employee of the Sacramento District and consultant to the New Orleans and Vicksburg districts and various other districts of the Corps of Engineers and to the Office of Chief of Engineers, U.S. Army, Washington. Manuscript received July 24, 1979; accepted July 26, 1979. prolonged destruction of the prairies. Another vast change introduced by the white man has been his attempts to control the preeminent central Missis- sippi River which drains much of the lower United States and part of Canada. The river and its appurtenances com- prise geographic and geological factors. As such, it is dif- ficult to control and, in fact, cannot be controlled except within very definite narrow limits. Thus, unlike the biotic provinces conquered and partially obliterated by man, the Mississippi gives the impression of fighting back at encroach- ments upon its domain. Obviously, if mankind is to control the river, even to a small extent, we must know as much as possible about it. Herein the writer analyzes to some extent the characteristics of the annual flow. At the end of the present year, 1979, we shall have a time series of only 80 years of adequate data dating from 1900 to consider. Variations in previous flows are considered where they are known. BACKGROUND INFORMATION The Mississippi River watershed is exceeded in area on Earth only by the watersheds of the Amazon and the Congo. It drains two thirds of the lower United States (some 283 284 GUNTER 1,244,000 square miles) and about 13,000 square miles of Canada. The average rainfall over this area is about 30 inches and about one fourth of this reaches the sea by way of the river. The economic and historical influences of this great river system have been enormous. Geographical, geological and hydrographical descriptions, and some history of the river have been given by Trowbridge (1930), Elliott (1932), Russell (1936, 1948), Fisk (1944) and Gunter (1952). The river begins in Minnesota and flows southward within its alluvial plain between the escarpments of its valley. In a few places it touches these escarpments as at the bluffs of Vicksburg and Natchez. The river has a natural levee all along its floodplain which consists of fine, alluvial soil that forms from sand and silt deposits when the river overflows its banks during high-water periods. Essentially the load is deposited quickly as the cur- rent speed falls after it leaves the channel. This levee slopes away from the river, at the rate of about seven feet to a mile, to the low-lying swamps on either side. This natural levee system was the finest land available when the first white man came into the country, and it was better drained than any other land of the area. High water comes every year between December-January and June- July. A flood ensues when the river overflows its natural levees. The area which is subject to flooding under natural conditions consists of 34,600 square miles or 22.1 million acres south of Cairo, Illinois, including 1 8,000 square miles of deltaic plain. Floods occur about every three years under natural conditions, but nowadays they are largely restrained by man-made levees. The fine arable land along the river which remained high and dry after the spring floods had gone down, in contrast to the swampy areas back away from the river, led to exten- sive settlement up and down the river banks, beginning when New Orleans was first settled in 1717. The river was the great travel connection from the days of the pirogues and canoes of the Indians and early explorers, to the time of the flatboats and steamboats and today the powerful diesel-motor towboats, with their huge strings of barges, and the ocean-going freighters. The fact that the river was the great avenue of travel and commerce, reinforced the tendency of the Europeans to settle along its banks. The only alternative was for the settlers to go beyond the swamps to the edges of the valley itself, that is to the escarpments, which were sometimes as much as 50 miles away. The river did not overflow and discommode the settlers every year but rather about once every three years, and even so, the floods were not very high in the beginning, although they filled in the back waters at times and went to the very edges of the valley, being commonly 50 miles wide along the lower river and even 80 miles in the widest place. But the vast areas of swamps lying alongside the river acted as overflow basins for floods and when the white man first came to live along the river, low levees or banquettes, three feet high around the Vieux Carr£ or Old Square, sufficed to protect the settlement of Nouvelle Orleans. In brief, it may be said that various situations and condi- tions constrained the white man to settle in areas which were naturally part of the river’s overflow area and which was subject to flooding. Circumstances which were not even recognized and of which the future portent was not foreseen, set the European settler upon the course of opposing and fighting the river rather than frying to live with it. Living with the river would have entailed building human dwellings and other structures on pilings or earthen banks about three feet high. However, it was easier to build a low embankment around the town of New Orleans and this was first completed in 1721 . In effect, the colonials built a ring levee. This was a rather innocent beginning, but as settlers moved up and down the river they were forced for their own protection, and later by law, to build levees and the river was cut off more and more from its natural overflow areas. As this took place, the floods and in turn the levees became higher so that now they are up to 40 feet. This situation was aggra- vated along the lower river by the closure of former distribu- taries, Bayou Manchac to the east just below Baton Rouge, and both Bayou Plaqucmine and Bayou Lafourche lower down on the west bank. This situation was reviewed and summarized by Gunter (1952, p. 123) in the following words: “Levees grew ever higher as the river was cut from its flood basins and so did floods. Today levees at some points are thirty-five feet high. In addition many tributary streams were leveed and they in turn were cut off from their flood basins. Maps of the present system show a bewildering tracery of leeves, quite difficult to describe in detail, which however is unnec- essary for our purposes. It is sufficient to say that the total levee system was around 991 miles long in 1880 and 2,130 miles long in 1935. Up to 1885 the effects of levees were not so great as they have become since. According to Elliott (1932, p. 83) the flood of 1882 may be taken as typical of a major flood prior to extensive levee con- struction. ‘Comparison of succeeding flood crests with this flood gives a definite indication of the increase in flood heights.’ He gave figures taken at the Carrollton (New Orleans) gauge showing that the crest was at 14.95' feet in 1882, 16 feet in 1890 and 21 feet in 1912. The Red River Landing gauge regis- tered 48.50 feet in 1882, 53.20 feet in 1912 and 57.45 feet in 1927. The greatest flood of all was in 1927 when numerous crevasses modified flood heights on the lower river, making them useless for comparison. At the Cairo, Illinois gauge the 1927 high water crest was at 56.4 feet. The highest previous crest was at 54.69 feet in 1913. At the time of the 1912 flood the gauge stood at 54.0 feet. In summary, levee construction started in 1717, 235 years ago, at New Orleans and was a gradual the Annual Flows of the Mississippi River 285 process up until about 1880. From that time the rate was accelerated, until the nineteen-thirties when the whole system was greatly extended and more or less stabilized, following the disastrous flood of 1927. Flood heights became higher as the levee system increased.” Viosca (1927) discussed the developments that would have come about along the river if the white man had not elected to fight it in the beginning and he and Gunter (1956, 1957) discussed the changes which have taken place within the great valley. Gunter (1952) has also discussed some gen- eral changes which have taken place around the river's mouth. At the present time about three fourths of the 35,000- square-mile floodplain area has been cut off from the river by levees. It appears that devegetation of the land also has tended to increase the peaking of annual floods, which means an increase in flood heights. The most disastrous flood of all time came in 1927. Efforts at flood control became coordinated and administered by the Corps of Engineers, U.S. Army, following the 1927 catastrophe. RIVER FLOW AND MAJOR FLOODS The Atchafalaya Problem Table 1 gives the measured flows of the Mississippi River for each year of the twentieth century in terms of mean flow per second for each year. These figures were furnished by the New Orleans District of the Corps of Engineers. Data before 1900 are unavailable or unreliable. Today the Mississippi River has two large natural distri- butaries, the main river and the Atchafalaya. The flows of the two distributaries are given in the same terms. According to Elliott (1932) the Atchafalaya in 1858 carried 77,061 cfs of water during high-water stages. Insofar as the flood or high-water flow is at least around 700,000 cfs in the main river, the Atchafalaya had 10% or maybe even less of the flow in 1858. Since that time the Atchafalaya has grown greatly. This growth has been common knowledge and has been written up in the New Orleans newspapers many times. It was known to early writers such as Mark Twain. In the early 1930s the writer talked to old people who had seen footbridges across the original Atchafalaya Bayou (Gunter 1952) in antebellum days. Apparently, it is an old main channel of the river of a thousand years or so ago, which changed to the left of the direction of flow and is now trying to change back again. According to Comeaux (1970) a raft in the upper Atchafalaya began to grow sometime between 1500 and 1778, but with Shreve’s cutoff, which removed a large oxbow in the main river, the Atchafalaya was virtually bypassed and it decreased in size until 1839, when raft removal was first attempted. In 1861, the process was completed and the Atchafalaya began to grow rapidly. Floods decreased along the lower Mississippi and increased on the Atchafalaya until all farming along that stream came to an end. TABLE 1. Mississippi River system flows. This consists of the combined Atchafalaya River flow at Simmesport and the Mississippi River flow at Red River Landing (at Tarbert Landing after June 1963), furnished by New Orleans District, Corps of Engineers, U.S. Army. Figures are in thousands of cubic feet per second and each figure is the mean flow per day for 365 days. Year Mississippi River at Red River Landing Atchafalaya River at Simmesport Combined Flow 1900 432 64.7 497 1901 377 55.4 432 1902 461 70.2 531 1903 639 136 775 1904 465 76.8 542 1905 576 104 680 1906 592 103 695 1907 676 134 810 1908 667 146 813 1909 581 105 686 1910 473 73.7 547 1911 459 70.6 530 1912 646 138 784 1913 584 122 706 1914 409 69.7 479 1915 653 126 779 1916 640 140 780 1917 510 93.8 604 1918 400 61.9 462 1919 602 120 722 1920 657 145 802 1921 527 95.4 622 1922 566 125 691 1923 590 116 706 1924 548 98.3 646 1925 368 50.0 418 1926 476 98.8 575 1927 867 239 1106 1928 601 147 748 1929 643 177 820 1930 419 99.8 519 1931 283 57.8 341 1932 516 139 655 1933 522 145 667 1934 292 71.8 364 1935 574 177 751 1936 346 85.5 432 1937 514 158 672 1938 511 161 672 1939 445 143 588 1940 313 94.9 408 1941 376 114 490 1942 499 157 656 1943 520 165 685 1944 475 159 634 1945 683 264 947 1946 509 202 711 1947 426 165 591 1948 448 173 621 1949 555 226 781 286 Gunter TABLE 1 . (Continued) Year Mississippi River at Red River Landing Atchafalaya River at Simmesport Combined Flow 1950 696 297 993 1951 625 256 881 1952 466 193 659 1953 373 152 525 1954 262 94.2 356 1955 363 139 502 1956 332 131 463 1957 548 238 786 1958 482 233 715 1959 382 161 543 1960 409 176 585 1961 514 236 750 1962 475 223 698 1963 268 110 378 1964 367 105 472 1965 416 187 603 1966 370 133 503 1967 385 170 555 1968 434 220 654 1969 457 225 682 1970 437 216 653 1971 388 191 579 1972 481 239 720 1973 720 377 1097 1974 586 322 908 1975 564 310 874 1976 374 164 538 1977 379 162 541 1978 470 202 672 In the first decade of the present century the Mississippi proper carried 84.5% of the river flow while the Atchafalaya River carried 15.4%. From 1970 to 1978, inclusive, the Atcha- falaya carried 32.9% of the total flow and the Mississippi carried 66.1%. The change in the partition of flow has been approximately an 18% decline in 78 years in the Mississipi flow as shown by Table 2, with a commensurate increase in the Atchafalaya. If the present tendency continues, the Atch- falaya River will carry as much water as the Mississippi in about 49 years from the present (1979) or circa year 2038. Apparently, aggrandizement by the Atchafalya still contin- ues in spite of attempts by the Corps of Engineers to stop it. In fact, Table 3 shows, in terms of the mean flows for each month, that during the flood year of 1973, the Atchafalaya took over 37% of the flow. Nevertheless, IheOld River Con- trol is operated by the Corps to retain approximately the same distribution of flow as would have been obtained under natural river conditions of 1950. The larger Floods Measurements of river flow were not as accurate in the 1800s as they are today, but there are indications (cf. Elliott 1932) that the 1882 flood was about equivalent to those of 1927 and 1973. Thus these three floods are roughly equivalent to 50-year floods. TABLE 2. The mean flow of the Mississippi and Atchafalaya livers in decade intervals from 1900 to 1978 in thousands of cfs. Percentages are given below. Decade Mississippi Atchafalaya Totals 1900-1909 546.6 99.5 646,1 84.5 15.4 1910-1919 537.6 101.7 639.8 84.0 15.9 1920-1929 584.3 129.1 713.4 81.9 18.0 1930-1939 442.2 123.9 566.1 78.1 21,8 1940-1949 480.4 172.0 652.4 73.6 26.3 1950-1959 452.9 189.4 642.3 70.5 29.4 1960-1969 409.5 178.5 588.0 69.6 30.3 1970-1978 439.9 218.3 658.2 66.1 32.9 The 1927 flood is rated as the most destructive of all time because there were more and greater crevasses in the lower floodplain and no doubt there were greater areas of flooding. In part this is due to the fact that levees were not as good then as they are today. It is also partly because a major portion of the flood control system, consisting of reservoirs on the upper river, the Bonnet Carre Spillway, and the major floodways of the Atchafalaya River, did not exist at that time. Even so the 1973 flood put 13 million acres of the 22-million-acre floodplain under water at one time. Actually about one fourth of the floodplain today is left free and not cut off from the river by levees. Final data on the combined daily flow of the Mississippi and Atchafalaya rivers, as shown in Table 4, give a lower total flow for 1973 than 1927. Table 4 shows the daily mean flows for each month. It should be noted, too, that the greater flow of the river fell in the first six months during 1973, while in 1927 flood waters lasted for seven months through July. The 1973 data and the flood data for 1927 were used to calculate the fact that during 1927 the river put 127.0 cubic nautical miles of water into the Gulf of Mexico, whereas in 1973 the figure was 126.5 cubic nautical miles. Figured another way the river flowed an average of 1,106,000 cfs during 1927 and 1,097,000 cfs in 1973 or 63,000 cfs con- stantly less during the latter year. So it appears that the 1927 flood was the greatest of record. The 1973 flood was about the same in magnitude and the two were remarkably similar; but the 1973 flood came and went without flooding on the lower river valley. There is no doubt that the Bonnet Carre Spillway and the floodways of the Atchafalaya played an Important part during this period of crisis in flood control. The annual Flows of the Mississippi River 287 TABLE 3. Daily discharges fur 1973, computed in thousands of cubic feet per second. Mississippi River at Tarbert Landing, Mississippi Atchafaiaya River at Simmesport, Louisiana Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1 935 822 759 1093 1357 1216 703 367 247 222 394 599 1 440 399 406 548 722 661 439 202 129 93 208 290 2 936 842 722 1112 1393 1191 643 392 241 225 374 656 2 440 407 404 558 719 674 429 212 126 97 204 312 3 938 854 686 1154 1327 1159 627 403 239 227 360 700 3 440 414 385 571 682 648 420 219 123 102 187 330 4 914 863 654 1181 1329 1126 614 408 239 231 346 740 4 443 416 368 570 685 601 412 222 125 103 181 347 5 888 867 620 1205 1403 1070 596 407 238 231 350 767 5 439 420 351 573 725 625 405 222 128 115 198 342 6 885 873 594 1241 1388 1090 572 399 237 235 357 785 6 441 424 339 580 720 620 397 219 136 125 202 341 7 892 875 S80 1273 1373 1045 550 388 234 271 374 798 7 444 423 333 595 709 579 389 214 141 137 216 348 8 897 881 565 1292 1322 1054 535 374 232 307 394 826 8 446 425 332 603 727 607 382 207 143 146 223 361 9 900 872 559 1291 1447 1029 5)1 355 230 336 402 844 9 452 426 330 609 731 606 375 198 142 161 223 375 10 902 861 563 1268 1392 1037 494 335 228 359 403 861 10 454 427 326 620 740 549 360 187 141 172 224 390 11 904 846 582 1291 1354 1012 467 313 229 377 397 878 11 456 426 331 622 759 562 344 175 141 177 223 403 12 908 839 591 1352 1428 1014 447 294 232 394 386 892 12 459 427 340 634 781 570 328 165 142 182 219 399 13 909 842 618 1296 1418 992 441 279 235 408 374 909 13 461 429 347 626 727 542 314 162 148 188 215 398 14 908 858 660 1342 1426 978 433 269 231 415 362 933 14 464 434 357 626 742 552 305 155 156 195 204 401 15 911 868 709 1335 1428 983 430 263 227 418 349 946 15 464 442 376 679 736 574 297 145 155 207 193 416 16 892 873 745 1387 1498 1003 421 260 223 423 342 954 16 465 439 401 691 763 528 287 138 150 211 183 418 17 882 875 780 1359 1441 979 414 255 220 427 334 962 17 464 439 414 710 749 530 277 135 145 217 175 421 18 867 880 800 1408 1440 957 404 254 218 430 328 968 18 466 440 424 730 760 539 274 133 140 224 167 414 19 848 885 814 1323 1402 975 396 260 222 427 321 950 19 446 439 433 668 739 546 268 134 122 235 159 414 20 819 876 833 1368 1426 964 384 267 216 425 318 954 20 429 442 441 686 739 550 265 137 121 238 156 407 21 796 871 857 1233 1409 937 372 277 207 430 311 925 21 412 436 445 674 737 534 251 142 121 233 155 387 22 765 866 868 1286 1392 910 361 283 218 435 302 886 22 396 433 454 648 727 515 239 146 101 231 151 384 23 742 860 887 1298 1370 878 350 285 213 439 299 834 23 383 430 462 596 730 503 228 144 109 229 149 375 24 708 856 945 1279 1361 856 339 291 209 437 305 805 24 376 4 25 483 688 749 513 216 141 113 230 150 373 25 698 849 983 1285 1299 856 328 296 207 437 314 801 25 371 421 499 641 727 463 209 142 112 230 156 373 26 699 839 995 1244 1372 850 319 296 210 439 327 791 26 369 416 5)3 683 767 492 201 144 101 227 162 372 27 709 819 1005 1280 1299 819 300 297 208 434 355 774 27 371 410 528 674 733 475 191 141 91 229 178 366 28 727 789 1021 1260 1352 811 293 283 209 430 407 724 28 375 408 523 692 704 472 183 138 89 228 206 361 29 751 1041 1360 1297 744 294 268 212 427 454 717 29 381 521 687 706 472 180 137 90 224 232 356 30 767 1054 1433 1220 763 308 260 218 420 530 715 30 386 531 724 687 452 182 134 92 222 260 352 31 792 1072 1207 336 256 411 720 31 392 539 689 193 129 215 351 Mean 842 857 779 1284 1373 977 441 311 224 372 362 826 Mean 427 426 417 640 729 552 298 165 126 188 192 373 Max. 938 885 1072 1433 1498 1216 703 408 247 439 530 968 Max. 442 399 539 730 781 674 439 222 156 238 260 421 Min. 698 789 559 1093 1207 744 293 254 207 222 299 599 Min. 369 399 326 548 682 452 180 129 89 93 149 290 TABLE 4. Monthly flow of the Mississippi and Atchafaiaya rivers in terms of the mean flows computed in thousands of cubic feet per second. Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1927 1117 1311 1395 1662 2223 ■ B 348 652 1973 1269 1283 1196 1924 m IQ m 554 1199 The Periods and Times of Great Floods De la Vega, the chronicler of De Soto’s explorations, recorded a flood that began on March 10, 1543, which was said to have crested 40 days later, and lasted about 80 days. It was said to cover the valley for 20 leagues on each side of the river. In terms of the old Spanish league, this would be a distance of about 105 miles and the flood must have touched both escarpments of the valley. This distance seems to be excessive, but in any case, this was clearly a very large flood 436 years ago. We have nothing to compare it to after- wards. The location was thought to be at Helena, Arkansas. La Salle recorded another flood in 1664. The French settlers at New Orleans encountered a flood in 1717 and again in 1718 before levees were constructed. The city was flooded by crevasses at least eight times up to 1849. From 1717 to 1816, there were 17 floods recorded on the river 288 Gunter according lo the summary given by Elliott (1932, pp. 105- 113), but between 1817 and 1916, there were 37 recorded floods. Thus, it would appear that levees brought more floods by raising flood heights, if the flood occurrences were reliably reported. However, Elliott says that they were not well recorded before 1799. As he pointed out, the hydraulics of the river have become much more efficient throughout the years so that the river could accommodate a 2,000,000-cfs flow in 1932, although between natural banks it carried only 1 ,000,000 cfs. Also according to Elliott, the 1882 flood was the last typical major one before extensive leveeing. In the 47 years prior to and including 1882, there were 19 floods; in the 47 years from 1883 to 1929, there were 16 floods. Thus, the floods were not increased after 1882 (Elliott 1932, p . 1 04) although lcvcc and flood heights rose on all the gages* from St. Louis to Carrollton (New Orleans). Actually there were 37 floods in the 1800s and only 27 floods in the first 80 years of this century, counting flows of over 700,000 cfs as a flood year, including the year 1979, which is not over at this writing. There have been only nine floods in the past 30 years by the same token and 17 in the first 50 years of the century. Actually, Elliott’s criteria for floods in the twentieth century presumably were gage heights, crevasses, etc., but since 1927, there have been no crevasses. Looked at another way, from about 1775 on, it seems that considerable attention was paid to floods and in fact measurements by a gage at Natchez were attempted in 1770. From that year to 1929, inclusive, there were 53 floods listed by Elliott (1932) or a flood every 2.87 years. The annual river flow, as shown in Table 1, is generally very high in flood years, but not always. In 1922, the average flow was only 691,000 cfs but there was a flood, of which Elliott said (1932, p. 114), “The 1922 flood stages were well below previous records at all gaging stations above White River, but from that point to Carrollton they exceeded all previous records.” Three crevasses occurred. Because of the last instance, we have listed as a flood year all years in Table 1 in which the total “instantaneous” flow was above 700,000 cfs. There were 25 such years out of the 78 total during this century so far, giving an average of one every 3.00 years. The approach then seems to be fairly consistent with actual overflows in switching to high-water years with no crevasses as a means of measuring floods. But the idea is also arbitrary and floods listed by Elliott for the ceniury up to 1929 were in years 1903, 1907, 1912, 1913, 1916, 1920, 1922, 1927 and 1929. If the year 1927 is removed from this series, the range and mean cfs of flows were 691,000 lo 820,000, and 771,000, whereas the same figures for 1908, 1915, 1919, 1923 and 1928, which were not listed as flood years, were 706,000 to 813,000 and 754,000. It is clear that flood years depend a lot on concen- tration of river flow in certain months, and a nonflood year may have higher average flows than some flood years. These high-water months are nearly always in the first six or seven months of the year. Some high-flow months also come in the latter part of the year, such as December 1973, and if so they contribute to flooding in the following year. A great drought on this continent began in the early 1930s and ended in the late 1950s, so that possibly there will be more rain in the next 50 years. In fact, Price and Gunter (1943) pointed out that a change to drier weather took place in south Texas about 1870. The idea of a climatic change was laughed out of court by the scientific community at that time, but it is now recognized that a definite change to drier and warmer weather took place in about 1876 in the United States and was reversed again in the late 1950s, 1957—1958 to be precise. Today we have high waters or “swells” in the river, as some early writers called them, without any flooding at all outside the levees. And so it is to be hoped that in the future, variations in river flow will be shown by gage heights and cfs readings rather than floods and destruction. This does not mean that all-out leveeing is advocated. Rather it would seem that return to the river of the vast overflow areas between the natural levees and the escarpments of the valley should be effected wherever possible. This would permit lower levees and enrichment of the valley by its natural soils rather than their artificial waste into the sea, which prevails today. Prior to lire flood of 1882, there was not extensive leveeing, but there were accounts of floods by various authorities, according to whom the greatest floods were in 1782, 1785, 1791 and 1809. During the latter year the Natchez gage was installed, and people on the lower river thought the Great Lakes were emptying southward through the river. From then on this gage registered at 48.0 feet and above in 1813, 1815, 1823 and 1828. This gage was at 47.8 in 1858 and 49.0 in 1859. It registered 45.75 in 1882. The St. Louis gage came into use in 1826 and most of the other gages in 1844. These gave more objective information on floods. The years 1840 and 1844 had major floods. The written accounts of Elliott (1932) and the gage readings indicate that the greatest floods were 1782, 1828 and 1882. Thus 1782, 1828, 1882, 1927 and 1973 would be on 48-year intervals, the so-called 50-year floods. Possibly in 1782, 1828 or 1882 there were 100-year floods, but we have no objective data for precise comparisons. But subjec- tively the accounts leave little doubt that all of these would rank minimally as 50-year floods. In 1882, the whole Mississippi floodplain, 34,600 square miles, was reported to have been flooded. The 1927 flood followed high rises on all watersheds contributing to the Mississippi River. It scarcely seems possible that in a relatively stable geo- logic and climatic era that the river flow could be multiples of times what it has already been in the last few thousand *A variant of “gauge” used invariably by the Corps of Engineers. the Annual flows of the Mississippi River 289 years. That would mean that the so-called 500- or 1,000- year floods would possibly be less than 100% or twice dif- ferent from the average. In any case, we are approaching a 250-year record of the river and there seems to be some evidence for a 50-year cycle of great floods in which the river flows a little less than twice the mean flow for an average year. The known minimum annual flow is 341,000 cfs and the known high is 1.106.000 cfs, the mean being 646,000 or rather close to flood-year flows (700,000 cfs) most of the time. The median is 655,000 cfs. These data are all taken from Table 1 . It should be remembered that these figures are the means for the whole year. In 1939, there was one day at Red River Landing when the Mississippi flowed only 85,000 cfs for a day. According to Elliott (1932, p. 95) climatic experts have estimated that the river flow could vary up to about 3,000,000 cfs, which is 21 .4% above the 2,261 ,000 greatest flow which has been observed. Perhaps this would come with a 500-year flood. Some Statistics of Flows The mean daily flow of the Mississippi River, as shown by Table 1, ranged from 341,000 in 1931 to 1,106,000 cfs in 1927. The lowest daily combined flow during this 79-year stretch has not been determined but the highest was 2.261.000 on May 16, 1973. The reader should hold in mind that these figures are in terms of the mean flows in cubic feet per second for the whole 24-hour day. The lowest instantaneous flow of the Mississippi proper has been given as 85,000 cfs. For the combined distributaries it must have been 100,000 cfs or a little more. The statistical measures of the central tendency of an array of figures, such as the Mississippi River flows, are a powerful but simple statistical tool which is often neglected. The mean or average annual flow has already been given as 646,304 cfs. By coincidence, this is almost precisely the annual figure for 1924. In the 1900-1978 time series, 38 years were equal to the mean or below it, 41 years exceeded the mean. The measurement of the median number shows that it is 655,000 cfs. The mode of all measurements was at 655,400 cfs, very close to the median. It seems that the central tendency figures are all skewed a little to the left of midpoint or a little less than the point between the extremes. This seems to follow from the fact that the flood and high-water periods are generally not as long or as extensive as the low- water periods, even in some flood years. The years 1927 and 1973 were exceptions, Similarly, Table 5 shows that most flows were in the 500,000 and 600,000 classes, with 53 of the 79 years, or 67%, below 699,000. In terms of dispersion, the decile annual flows seem to be at 432,000 and 820,000 cfs, and the quartiles are at 531 .000 and 748,000 cfs annually. This also shows a certain skewness towards the low side. The standard deviation was calculated to be 159.4 and the coefficient of variation was 0.247. TABLE 5. Annual flows of the Mississippi River numbered in class ranges of 100,000 cfs from 300,000 to 1 ,100,000 for the twentieth century. Figures in thousands. Class Ranges Annual Flows 300 3 400 10 500 17 600 23 700 15 800 6 900 3 1,000 1 1,100 1 Inspection of Table 1 shows that high-water years were not particularly associated. In 1903, 1912, 1913, 1916, 1920, 1 929 and 1937, there were low-water years (less than 500,000 mean cfs) within the second year before or after a flood year. In contrast, in 1907, 1922, 1950 and 1973, there were high-water years (over 800,000 cfs mean) next to or within the second year of the flood years. In summary, there was continuous high water or a tendency towards several such years together during four flood years, but in seven flood periods the river was variable, so to speak, with high- and low-flow years close together. One of the lowest river flows of all time occurred in the summer of 1976, three years after the great flood of 1973, and three years before the 1979 flood and the Bonnet CarnS Spillway opening. Biological Importance of the River The river brings down large amounts of nutrient salts and cool, fresh water into the bays and estuaries of Louisiana and Mississippi during the late winter arid spring. These factors have large effects on fisheries production of the area but no exhaustive treatment has been presented. Biologists know that oyster reefs are killed by floods (Gunter 1953) and that larval brown shrimp are repelled sometimes by walls of cold, low-salinity water as they try to enter the estuaries during the early months of the year. But an ade- quate treatment awaits a better and longer series of biological data. This concerns the most productive fishery area on the continent (Gunter 1963) and presumably the information will be forthcoming. Ancient Flows According to Emiliani et al. (1976), the Mississippi River used to flow 2 to 5 times more than at present, but this was 11,000 to 7,000 years ago when the Wisconsin ice sheet of 290 Gunter North America was melting. The climate at that time was nothing like that of the fairly stable present. During an earlier period of glacier melting some 18,000 years ago, a lake containing some 1 ,800 cubic miles of water behind an ice dam in Washington, Idaho and Montana, made its way to the Pacific some 330 miles away following melting of the dam. The flow was 10 million cubic meters per second or 345 million cfs or 10 times the combined flows of the rivers of the world (Snow 1976). It dug the Grand Coulee and cleared out the Columbia River Gorge. It was all over in 30 days. Such cataclysmic water flows are simply not characteristic of today’s climate. CONCLUSIONS AND SUMMARY In 1900, the Corps of Engineers instituted measurements of the flow of the Mississippi and Atchafalaya rivers, the two distributaries of the Mississippi River system. These are given in cubic feet per second for the whole year as a mean or average figure. A seriesof 80 integers will have been collected at the end of 1979. The flow has ranged from 341,000 cfs in 1931 , four years after the greatest flood, to the greatest annual flow of record in 1927 at 1,106,000 cfs. The mean- annual flow has been 646,000 cfs to the end of 1978. The median is at 655,000 feet and the mode is 655,400 cfs. The decile figures are 432,000 and 820,000 cfs. The quartiles are at 531,000 and 748,000. All of these figures seem to be on the low side or skewed to the left, but most flows are also on the low side and outnumber flood years by two to one, there being one flood in three years. Since 1928, when the Corps of Engineers took over flood control, there have been virtually no crevasses and levee breaks, and floods are registered by high water, arbi- trarily set here with an annual-mean flow of 700,000 cfs. Even so there have been some floods with crevasses at lower flow figures and some high-flow years in the 800,000-cfs class without floods. This comes about because floods depend also on the concentration of runoffs in given months. The measurements of dispersion show 159,408 cfs for the standard deviation and a coefficient of variation of 0.247, none of which is particularly noteworthy. Apparently the Atchafalaya carried about 10% of the total flow in 1858. It has grown to approximately 33% of the total flow and, during 1973, it carried 37% of the total flow. The river’s greatest measured flow, 2,261,000 cfs, has been only 6.63 times the mean of its lowest annual flow, 341,000 cfs. The floods of 1828 and 1882, which covered the flood- plain, fit well with 1927 and 1973 as 50-year floods, although the older floods may have been greater. These floods seem to come when all tributaries are contributing heavily. These seem to be about the peak floods that can come under the present climatic regime. The climatologists estimated for Elliott (1932) that the maximum expected flood would be about 3,000,000 cfs. This is only 21.4% greater than the greatest high that has been experienced recently, 2,261,000 cfs, on May 16, 1973. Presumably, the 3,000,000-cfs flood would be a 500- or maybe even a 1000- year flood. With spillways, floodways, reservoirs upstream and strong levees, all operated judiciously along with some sacrifice of the floodplain, it would seem that we could hope to get by such a crises without an overwhelming catastrophe. But such a confrontation between man and the river is certain to come and it must be met with careful planning and relentless vigilance. REFERENCES CITED Comeaux, Malcolm L. 1970. The Atchafalaya River Raft. Louisiana Studies. Winter, pp. 217—227. Elliott, D. C. 1932. The improvement of the lower Mississippi River for flood control and navigation. U.S. Waterways Experiment Station, U.S. Army Corps of Engineers, War Department. 345 pp. Emiliani, Cesare, Claes Rooth & Jerry J. Stipp. 1978. The late Wisconsin flood into the Gulf of Mexico. Earth and Planelury Science Letters 41:1 59- 1 62. Fisk, H. N. 1944. Geological investigation of the alluvial valley of the lower Mississippi River, Mississippi Valley Commission, Vicksburg. 87 pp. Gunter, Gordon. 1952. Historical changes in the Mississippi River and the adjacent marine environment. Publ. Inst. Mar. Sci., Univ. Tex. 2(2):119-139. ______ . 1953. The relationship of the Bonnet Carre Spillway to oyster beds in Mississippi Sound and the “Louisiana Marsh,” with a report on the 1950 opening. Publ. Inst. Mar. Sci. t Univ. Tex. 3(1):17— 71. . 1956. Land, water, wildlife and flood control in the Mississippi Valley. Proc. La. Acad. Sci. XIX:5-10. . 1957. Wildlife and flood control in the Mississippi Valley. Trans. N. Am. Wildl. Nat. Resour. Conf. 22:189-196. . 1963. The fertile fisheries crescent. J. Miss. Acad. Sci. 9:286-290. Price, W. Armstrong & G. Gunter. 1943. Certain recent geological and biological changes in South Texas, with consideration of probable causes. Proc. Trans. Tex. Acad. Sci. 26:138—156. Russell, R. J. 1936. Physiography of lower Mississippi River Delta. La. State Dep. Conserv,, Geol. Bull. 8:3-199. J 94 8. Coast of Louisiana . Bull. Soc. beige Geol. Paleontol. llydrol. 57:380-394. Snow, Dean. 1976. The Archaeology of North America. The Viking Press, Inc., New York. 272 pp. Trowbridge, H. C. 1930. Building of Mississippi delta. Am. /Issoc. Pet. Geol. Bull. 14:867-901. Viosca, Percy, Jr. 1927. Flood control in the Mississippi Valley in its relation to Louisiana fisheries. Trans. Am. Fish. Soc. 57:49-61. Gulf Research Reports Volume 6 | Issue 3 January 1979 Adaptation of a Brown Water Culture Technique to the Mass Culture of the Copepod Acartia tonsa John Ogle Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.10 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Ogle, J. 1979. Adaptation of a Brown Water Culture Technique to the Mass Culture of the Copepod Acartia tonsa. Gulf Research Reports 6 (3): 291-292. Retrieved from http:// aquila.usm.edu/gcr/vol6/iss3/10 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(2)usm.edu. Gulf Research Reports, Vol. 6, No. 3, 291-292, 1979. SHORT COMMUNICATIONS ADAPTATION OF A BROWN WATER CULTURE TECHNIQUE TO THE MASS CULTURE OF THE COPEPOD ACARTIA TONSA JOHN OGLE Oyster Biology Section , Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564 ABSTRACT The use of bay water, filtered to 5 microns, was found to be sufficiently nutritious to sustain an average of 232,000 adult Acartia tonsa per m 3 . Copepods survived up to 24 days as adults and produced up to 75 nauplii per adult. Nauplii could be sieved to produce copepods of known age or known parentage. Survival of nauplii to adults ranged from 15 to 88%. Culture water varied from 6 to 28 C in temperature, and from 1 to 26 ppt in salinity. INTRODUCTION The usefulness of the copepod Acartia tonsa (Dana) as a source of larval fish food and for bioassays involving cope- pods of known age has generated considerable interest in their culture. Culture systems for copepods have traditionally required the feeding of cultured algae (Kinne 1977). The culture of algae is time intensive and expensive, making it economically impractical to produce the numbers of cope- pods necessary for larval food. The use of bay water filtered through a 5-micron GAF filter bag has been found to be sufficiently nutritious to allow the rearing of moderate numbers of copepods at the Gulf Coast Research Laboratory oyster biology facility located at Point Cadet, Biloxi, Mississippi. Nitrate values of ambient water and the resulting phytoplankton, as indicated by chlorophyll-a determinations over several years, were found to be comparable to or exceed values for cultured- algae diets that were being fed to oyster larvae. This has led to Ihe use of the “brown water” technique for the operation of an oyster hatchery (Ogle 1979). The contamination of oyster larval cultures in late summer and fall by Acartia tonsa led to the use of the identical techniques for culturing copepods in moderate numbers throughout the winter and spring months. MATERIALS AND METHODS The culturing facility consisted of a 3.9 x 13 m (1 2 x 40 ft) greenhouse constructed of a double wall of poly- ethylene (Monsanto 602) stretched over polypropylene pipes anchored to the ground. The copepods are reared in four fiberglass circular tanks of 1890-1 (500-gal.) capacity. Bay water is pumped by a 1-hp pump from a pier extending 46 m (150 ft) into Mississippi Sound and passes through a Manuscript received August 3 1 , 1979; accepted September 28, 1979. 5-micron filter bag into the culture tanks. The water is not fertilized or aged. The tanks are stocked with approximately 1 million copepods and the water is completely changed three times weekly. The tanks are drained through 2,54-cm (1 in.) pipes into a sieve box which filters out the copepods before the water flows to a waste drain. Drains and air lines are changed with each water change. Tanks are hosed out, scrubbed and allowed to air dry between changes. Aeration is provided in each tank by a single stone from a vibrator pump. The copepods used for stocking were recruited from the wild by holding tanks of unfiltered water for several days and then removing the stage animals desired. By culturing unstocked tanks containing bag-filtered water it was demon- strated that no recruitment occurred from using water passed through a 5-micron filter. The various stages of copepods can be separated readily by utilizing sieves of various sizes. A 212-micron sieve will retain only the adults, allowing copepodites and nauplii to pass through. The copepodites will be retained by a 100- micron sieve and ihe nauplii by a 45-micron sieve, If cope- pods of known parentage arc desired, one can sieve a mixed population, retain the adults, and in the following change retain the nauplii from those parents. If animals of known age are required, the tanks can be sieved daily, thereby concentrating all nauplii hatched within the preceding 24 hours. These nauplii are then reared to maturity in separate tanks. After three changes during a week’s period, the nauplii will have grown to adults. On the fourth change (9 days), these copepods will themselves be producing nauplii. Contrary to previous reports of sensitivity to handling (Gentile and Sosnowski 1968), these copepods were handled somewhat roughly as they were routinely sieved and concen- trated into 10 1 of water, stirred with a plunger plate, and a 1-ml sample withdrawn and enumerated to estimate the total number of animals. 291 292 Ogle RESULTS Copepods were reared from November 1978 until May 4, 1979. During November and December, five successive gen- erations were reared, Naupliar production and survival were followed for one generation during the month of December, and production of an additional generation was followed during April (Table l). Naupliar production ranged from 2.3 to 75 nauplii per adult for the month of December and ranged from 2.2 to 10 nauplii per adult for the April brood. The copepods survived as adults for about 20 days during December and 24 days during April. Survival of the nauplii varied from 17 to 69% during December and 15 to 88% during April. During these studies, a life cycle was com- pleted in 9 to 12 days. Temperature ranged from a low of 5.5°C to a high of 27.7°C averaging 20°C, while salinity ranged from a low of 1 ppt to a high of 26 ppt averaging 12 ppt over the culture period. DISCUSSION Copepods have been reared in fertilized ponds previously (Raymont and Miller 1962) with densities of 100 and 200 per liter of water. However, several species were mixed and no control was possible over the population. Bay water was used in 1 -gallon jars by Reinle (1966) in his rearing experiments for producing small numbers of copepods. The production from the system used here averaged 232,000 adults per m 3 which is 580 times the maximum concentration of copepods found in adjacent waters (Mcllwairi 1968). This was accom- plished simply by removing competitors and predators and without fertilization or supplemental feeding. Production from these tanks was excessive to the requirements of bio- assay purposes and experimental larval fish-reaiing, but can- not meet the needs for mass fish-rearing projects. The results are encouraging and it is possible that with supplemental feeding, better handling techniques and more constant culture conditions, even higher yields might be achieved. TABLE 1. Naupliar production and survival of Aeartia tonsa during the months of December (1978) and April (1979). Date Brood Parents Numbers Produced Nauplii per adult Survival % Nauplii Copepodites Adults 12/14 1 180,000 410,000 300.000 70.000 2.3 17 12/18 2 160,000 1,200,000 1,000,000 830,000 7.5 69 12/22 3 80,000 2,000.000 1,100,000 1.300,000 16.4 65 12/26 4 20,000 1,500.000 830,000 _ 75.0 _ 12/30 5 20,000 540,000 - - 27.0 4/ 3 1 80,000 720,000 _ 220.000 9.0 31 4/ 9 2 70,000 700,000 - 490,000 10.0 70 4/16 3 60,000 130,000 - 20.000 2.2 15 4/23 4 50,000 170,000 - 150,000 3.4 88 REFERENCES CITED Gentile, J. & S. Sosnowski. 1968. Methods for the culture and short Mcllwain. T. 1968. Seasonal occurrence of the pelagic Copepoda in term bioassay of thecalanoid cope pod .4c II HI IV V VI 1 II Ill IV V VI Chlorophyeophyta Ankistrodesmus + + + + Bracteococcus + + Chbrnydomonas + + + + + + + Chloreila + + Chlorococcum + + + + + + + + + + + Chlorosarcina + Chlorosarcinopsis + + + + + + + + + + + Gleocystis + ' Klebsormidium + + + Microspora + Pedimonas + Pleua strum + + + Radiosphaera + Rhizoclonium + + + Spongio clitoris + Stigeoclonium + + + Tetracystis + + + + + + + Ulothrix + Ch xy sophy co phyta A mphora + + + + Botrydiopsis + Chrysosarcinia Fragilaria + + + + Navicula + + + + + + + + + + + + Nitzschia + + + + Ochromonas + + + + Cyanochloronta Anahaetia + + + + + + + + + Aphanotheca + + + Calothrix + + + Chroocodcus + + + + Microcoleus + Microcystis + + + Nodularia + + + Nostoc + + + Oscillaloria + + + + + + + + + + + + Schizorhrix + + + + + + + + + + + Spirulina + + + + + + Totals 12 13 19 12 9 12 14 12 11 9 12 16 DISCUSSION Differences in the total number of genera between the fall and spring flora were probably due to the decreased precipitation in the spring of 1979; this is particularly true of site III which drains a freshwater ditch. The high ratio of blue-green to green algae in this study may be due to the alkaline nature of the soils. The Cyanophyceae and Bacil- lariophyceae have been previously described as growing best in alkaline conditions (Lund 1946, Baker and Bold 1970, MacEntee et al, 1972, and Brock 1973). The diversity of blue-green algae in this study compares favorably with that reported by Sage and Sullivan (1978) for a Mississippi salt marsh. Although there were fewer genera of diatoms found in our study than reported for a coastal salt marsh by Sulli- van (1978), the diatom flora of the salt Hats compared favorably with that found in saline prairie soils by Nordin and Blinn (1972). Brock (1973) stated that the green algae are the least sensitive to pH and are almost universal in occurrence in soils. However, one genus, which is reported to be sensitive to pH, is Chlorosarcinopsis (McComb and Maples 1979). Olson (1961) reported this genus to be characteristic of Wisconsin pine forests and their acidic soils. McComb and Maples (1979) reported Chlorosarcinopsis as rare in the acid soils (pH 4.6 to 5.2) beneath a slash pine canopy. Chantanchat and Bold (1962) found Chlorosarcinopsis to be a prevalent genus in arid alkaline soils. Dykstra et al. (1975) reported that Chlorosarcinopsis was the most abundant alga in the coastal soils of Texas (pH 6,2 to 6.7). In this study, we found Chlorosarcinopsis to be the most common green alga in the alkaline coastal soils of Louisiana. A number of environmental parameters have been sug- gested as important factors affecting the distribution of soil algae. These include moisture, light, organic matter and phytotoxins. We believe that soil pH is one of the most important factors affecting the frequency and occurrence of soil algae, particularly in view of the known sensitivities of blue-green algae to low pH values. Further studies are , jneeded concerning the effect pH has on the distribution of edaphic green algae. Such studies should consider sensitiv- ities to pH values and distribution patterns at the species level. REFERENCES CITED Baker, A. F. &. H.C.Bold. 1970. Phycological Studies X. Taxonomic Studies in the Oscillatoriaceae. Univ. Tex. Publ. No. 7004. Brock, T. D. 1973. Lower pH limit for the existence of bluegrcen algae: evolutionary and ecological implications. Science 179: 480-483. Brown, R. M. & H. C. Bold. 1964 .Phycological Studies V. Compar- ative Studies of the Algal Genera Tetracystis and Chlorococcum. Univ. Tex. Publ. No. 6417. Chantanchat, S. & H. C. Bold. 1962. Phycological Studies II. Some Algae from Arid Soils. Univ. Tex. Publ. No. 6218. Drouet, F. 1968. Revision of the Classification of the Oscillatoriaceae. Acad. Nat. Sci., Philadelphia. Mono. No. 15. 370 pp. Dykstra, R, F., F. J. MacEntee, S. J. Bold & II. C. Bold. 1975. Some edaphic algae of the Texas coast. Tex. J . Sci. 26: 1 7 1 —1 75. Lund, J. W. G, 1946. Observations of soil algae. 1. The ecology, size and taxonomy of British soil diatoms. New Fhytol. 45 ;56- 110. short Communications 303 MacEntee, F. J., Sister G. Schrenkenberg & H. C. Bold. 1972. Some observations on the distribution of edaphic algae. Soil Sci. 114: 171 -179. & H. C. Bold. 1978. Some microalgae from sand. Tex. J. Sci. 30:167-173. McComb, K. P. & R. S. Maples. 1979. Some observations of algal communities in soils supporting slash pine {Finns elliolii Engelm.). Proc. La. Acad. Sci., in press. Nordin, R. N. & D. W. Blinn. 1972. Analysis of a saline tallgrass prairie ecosystem. IV. Preliminary investigation on soil algae. Proc. N. D. Acad. Sci. 24:8-17. Olson, J. W. 1961. Soil algae of some conifer and hardwood forests. Ph.D. dissertation. Univ. of Wisconsin. Round, F. E. 1965. The Biology of Algae. St. Martin’s Press. New York. Sage, W. W. & M. J. Sullivan. 1978. Distribution of bluegreen algae in a Mississippi Gulf coast salt marsh. J. Phycol. 14: 333-337. Sorensen, L. O. & J. T, Conover. 1962. Algal mat communities of Lyngbya confervoides (C. Agardh) Gomont. Publ. Inst. Mar. Sci. Univ. Tex . 8:61-74. Sullivan, M. J. 1978. Diatom community structure: Taxonomic and statistical analysis of a Mississippi salt marsh. J. Phycol. 14; 468-475. Gulf Research Reports Volume 6 | Issue 3 January 1979 Notes on Sea Beach Ecology. Food Sources on Sandy Beaches and Localized Diatom Blooms Bordering Gulf Beaches Gordon Gunter Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.14 Follow this and additional works at: http://aquila.usm.edu/gcr Part of the Marine Biology Commons Recommended Citation Gunter, G. 1979. Notes on Sea Beach Ecology. Food Sources on Sandy Beaches and Localized Diatom Blooms Bordering Gulf Beaches. Gulf Research Reports 6 (3): 305-307. Retrieved from http:// aquila.usm.edu/gcr/vol6/iss3/14 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(2)usm.edu. Gulf Research Reports , Vol. 6, No. 3, 305-307, 1979. NOTES ON SEA BEACH ECOLOGY. FOOD SOURCES ON SANDY BEACHES AND LOCALIZED DIATOM BLOOMS BORDERING GULF BEACHES GORDON GUNTER Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ABSTRACT Food production along sandy beaches is much different from that of rocky beaches. No large algae grow on sand beaches. Small filamentous green algae find footholds upon molluscs, mole crabs, strands of Leptogorgia and logs. Basic food along the sand beach is made up of diatoms, bacteria, unicellular algae and detritus; diatoms are probably the most abundant autotrophic organism; the beach bacteria are largely heterotrophic. Most food on sandy beaches comes from the sea. The sandy shore seems to be barren, but it swarms with plant and animal life. Food production has a seasonal aspect- Food strands more abundantly on sandy beaches because the force of water reluming to the sea is much less than that coming in. Beach materials are concentrated in a strand line. All organic materials are returned to the food cycle. Beached animal remains are consumed immediately until their breakdown products ooze away to enrich the sand substrata The material of logs may not be redistributed until a number of years have passed. Food producing algae arc diatoms, green algae, peridinians and blue-greens. Many of them are quite small and must be detected by bacteriological methods. They are probably quite significant. Food production from autotrophic algae appears to be relatively steady compared to drifting materials, which may vary enormously. Various types of food drift in as a result of dinoflagcllate blooms, catastrophic cold kills and stranding cetaceans. Seasonal drifting materials such as saigassum. Leptogorgia and jellyfish come in at particular times of the year. The river mouLh floods bring in material. The artificial jetsam of ships washes up on the beaches. Nutrients and salts are also concentrated on beaches from organic remains. As a result, a type of beach-hugging plank- tonic bloom has been noted on the Texas coast when the sea is calm following heavy rains. It consists of a yellowish-brown conglomeration of diatoms of the species Chaetoceras sp.> 15 to 20 feet wide along the shore for many, many miles. It follows heavy rains and the event is parallel to some aspects of the Florida red tide which occurs in calm weather, often following heavy rains, which are thought to bring chelating substances from the land. There are variations in time both in production of food on beaches and that washing in from the sea. Quantitative studies have not been made; nevertheless, certain nonquanti- tative observations and distinctions can be made. Food production and the sources of food for animals living along sand beaches are considerably different from those of rocky beaches. In contrast to rocky shores, no large algae grow on sand beaches except for filamentous green varieties which find small footholds upon certain molluscs such as Donax, the mole crab Emerita, strands of the alcy- onarian coral Leptogorgia , and other beached objects such as logs. They occur only in negligible amounts. Thus the basic food along the sand beach is microscopic plants, chiefly diatoms, bacteria, various other unicellular algae and detritus. The diatoms are probably the most abundant autotrophic organisms produced on the beach. Presumably the beach bacteria are largely heterotrophic. Most of the food consumed on sandy beaches comes from the sea. Pearse et al. (1942, p. 137) have made similar comparisons before and their words are worth quoting, “A marine sandy beach seems like an inhospitable place for plants and animals to become established. On a rocky, wave-beaten headland, where storms rage and intertidal areas are exposed alter- nately to cool, surging water and hot or cold desiccating air, there may be an abundant biota of attached seaweeds, hydroids, barnacles, clams, etc. The rocks may be literally carpeted with living things. On the other hand a shifting, Manuscript received April 9, 1979; accepted April 19, 1979. sandy beach is usually without much apparent life. There may be seen an occasional scuttling crab, a school of little fishes wiggling into the shallows, or a solitary sandpiper drilling holes with Ills long beak. In general a sandy shore seems to be a barren, clean place — admirable for bathing, but unpromising as a habitat where a biologist may collect or study animals. But appearances are deceiving. Marine littoral sands swarm with plant and animal life.” Along both rocky and sandy beaches food production has a seasonal aspect on temperate coasts, and the total production or peaks change from year to year. Neverthe- less, this process has aspects of steadiness and regularity. Possibly the same thing holds for drift of planktonic mater- ials from the sea, but information on that point is lacking. There is a second fundamental difference between the sand beach and the rocky beaches in that the rougher and more abrupt the beach, the less organic materials, especially large particles or bodies, tend to strand and add their incre- ment to the food of the shoreline. This holds true for two reasons. Rocky beaches are generally not wide and the water from waves and tide is channeled into quite strong currents returning to the sea. Floating objects may bump or bounce against rocks, which act as more or less pointed bodies, and be swirled out to sea again long before they ground on relatively level bottom. This is not to imply that stranding does not take place on rocky coasts, for it sometimes does and the total frequency may even be high, but the tendency is less than on an even-bottomed sand beach. The amount of food stranding on rocky coasts will 305 306 Gunter be at a maximum on gravelly or cobblestone beaches, which are not greatly different from sand beaches, and decreases with increasing roughness of the substrate and size of the rocks. On the bluff-like rock walls which prevail on some coasts, nothing strands except negligible scraps in small clefts and cracks. In contrast, everything which drifts into the surf of a sandy beach finally strands. The writer has pointed out before that returning currents are much weaker than those driving in from the sea and that all floating materials become beached where they drag bottom (Gunter 1946). Another factor which serves to further reduce the ability of breaking waves to carry flotsam (and sediments) seaward again was pointed out by Dr. David DeVries (personal communication). This is because part of the water from any breaking wave train percolates into the beach, to return slowly to sea level at that particular stage of the tide. This percolation (or loss of water) on the foreshore portion of the beach is most effective in reducing energy of return flow for the more gently slopping, sandy beaches. Stranding holds true for whale carcasses and other large objects and for microscopic animals and plants as well. Subsequent higher tides may move beached objects higher up on sandy beaches, but they are not carried back to sea. Thus there is an aspect of finality about the stranding or beaching process. This is especially true of the wide Gulf beaches, where, except for a few days a month, tides are negligible and occur only once a day. Hedgpeth (1957, pp. 590-591) discussed the sorting action of strong and weak currents of incoming and outgoing waves with regard to sand, beached organisms and “the usual flot- sam.” It is only reversed by extreme flooding from land or actual cutting away of the beach by currents, both of which are rare occurrences. Beaching has been so commonly observed that it has given rise to a descriptive term, i.e., the strandline. The flotsam of the ocean, extending as a line down the beach, is characteristic of this environment all over the world. Thus, although sand beaches are harsh envir- onments fitted only for the hardier organisms, they are not poor in food. To the contrary, food materials from a wide area are concentrated there within a narrow band. It goes without saying that all organic materials drifting into the beach are returned in some manner to the food cycle. Even the logs and grass stems are slowly broken down by bacteria, while the more edible products are consumed directly and immediately, both by permanent beach dwellers and certain land animals which remove organic materials away from the beach cycle. In this latter category the various birds probably play the greater part, Food-producing algae, according to Humm (Pearse et al. 1942), aside from the few macrophytes, are diatoms, green algae, peridinians and blue-greens. Some are only 3 microns in size and are seldom abundant enough to be seen. However, they are to be found everywhere by bacteriological methods and Humm states that they are probably more “significant in the economy of the beach than previously supposed.” Food production on the beach is relatively steady from autotrophic algae while that from drifting materials varies enormously in abundance. This matter has not been noted particularly in the literature and it is worth some attention. One group of drifting materials may be called sporadic or irregular. There are many examples over the world but only certain ones which have been observed personally will be mentioned. During the various cases of catastrophic mortality in the sea, huge numbers of animals, chiefly fishes, drift onto the beach. Photographs relating to dinoflagellate bloom or the red tide in Florida (Gunter et al. 1 948) and others connected with cold kills on the Texas coast (Gunter and Hildebrand 1951) have been published. Although the latter are of bay beaches, the writer (Gunter 1941) has noted that numbers of molluscs and fishes also wash up on the outside of beaches after the heavy cold kills. When these catastrophic mortal- ities come, and they are fairly common in widely spaced places on earth, the beach fauna receives a vast superabun- dance of food. It is well known that carcasses of cetaceans commonly come ashore. Numbers of locality records derive from such instances. Some species are prone to stranding in large num- bers while alive and large porpoises of the genus Globicephala are especially noted for this characteristic. Lowery (1943) published photographs of 49 of these animals that had become beached on the Louisiana coast following a hurri- cane. There are several other examples in the literature. Animals such as the ghost crabs Ocypode gather around such carcasses and dine upon the rich fare until the lique- fying remains ooze away into the sand. A second group of drifting materials may be called seasonal. On the Texas coast during the spring, vast wind- rows of Sargassum pile up on the beach. In certain years this drift is much greater than in others. In 1950 a band approximately 15 yards wide and 1 foot deep lined the Texas coast for over 300 miles. The weights involved must have been of the order of several thousand tons. During the summer the alcyonarian coral, Leptogorgia setacea (Pallas), rolls ashore in large masses and to such an extent that some thoughts have been given to the possibility of commercial use of the central horny core as a source of iodine. Still later in the year, when the winds blow from the north, thousands of the jellyfish Stomolophus meleagris Agassiz are sometimes beached. It should also be mentioned that Physalia and Velella move steadily into the strandline throughout the summer, but arc relatively scarce in winter. Certain beaches around river mouths, such as those of the Louisiana coast, receive influxes of material from land following the annual spring high-water periods. The amounts are greatly increased in flood years. These materials consist largely of plant remains, such as logs and the water hyacinth. The logs and dead trees sometimes make the beaches virtually impassable. Short Communications 307 In addition to the purely natural causes of organic depo- sition upon the beach, there are certain artificial ones, some of which have a seasonal character. Beaches near ship lanes or in the vicinity of coastwise traffic receive certain amounts of garbage. Trash materials from commercial fishermen’s catches seasonally drift up on some beaches. Near Port Aransas, Texas, certain fishes, chiefly tarpon, drift ashore in considerable numbers in summer due to the sport fishing industry of that town. Food materials drifting onto beaches may be roughly divided into two categories on a basis of whether their availability is immediate or deferred. Most animal remains are immediately available to the beach animals. On the other hand, plant remains must first be subjected to bacter- ial action and, in some cases, it may be years before they become totally available. Even the most edible animal bodies are not all consumed before part of them oozes away into the sand. These factors tend to have a damping or time- spreading effect upon the amounts of food available to beach animals following mass beachings, part of the food may become available over a time spread of a few weeks, months or even years after mass strandings. Humm (Pearse et al. 1942) made a particular study and found that the various bacteria species that destroy the celluloses and hemi-celluloses are quite common. They slowly destroy logs many years after their stranding. Chit- inoclastic bacteria have been found abundant on both Atlantic and Pacific beaches. It is clear that organic material drifting into the beaches varies enormously from time to time and this variation may be seasonal or completely sporadic, with some instances being years apart. Seasonal drifts usually cover a few hun- dred miles. The sporadic cases may relate to a few hundred miles of beach, but certain others, such as the strandings of cetaceans are entirely local. In any case, the concen- tration of organic materials in a narrow band on the shores of the seas is impressive. Pearse et al. (1942, p. 176) concluded “Sand beaches are not barren wastes, as they appear at first glance, but are swarming with life, and continually digest and furnish food to plants and animals.” The shifting sands of the seashore are probably not good sites for the process of fussilization. Nevertheless, the mere fact that the beaches are points of concentration makes them worthy of consideration in this respect. p ossils of open-sea animals have been described from beach deposits. It is obvious that remains of land animals and plants might also be found along old beach lines. It seems probable that nutrient salts are also concen- trated upon beaches, as would be expected from concen- tration of organic remains. This is suggested by a type of plankton bloom which occurs along the Texas coast. When the water of the Gulf is relatively calm, following heavy rains, a narrow band of diatoms sometimes forms along the Gulf shore of Mustang Island, extending from the water’s edge out 15 or 20 yards. The writer has seen it running along the shore without break for a distance of 16 miles, which was as far as it was traced, and extending on out of sight. The organisms were so thick they gave the water a yellowish-brown appearance somewhat like tea. The phe- nomenon has been observed two or three times and the organisms in one instance were collected in a plankton net by the late David Kramer (personal communication). He found that the water contained a perfectly uniform popu- lation of billions of Chaetoceras sp., which is commonly looked upon as an open-sea genus. Presumably, this diatom bloom takes place next to the beach when the common nutrient salts are leached out by rainwater and remain concentrated in the calm sea right next to shore, or they may wash down a chelating agent from land, as has been suggested for the Florida red tide. In any case, the parallel of blooms following rains and calm weather is suggestive. REFERENCES CITED Gunter, G. 1941. Death of fishes due to cold on the Texas coast. Ecology 22:203-208. . 1946. Records of the blackfish or pilot whale from the Texas Coast. J Mammal. 27:374-377. & H. H. Hildebrand. 195]. Destruction of fishes and other organisms on the south Texas Coast by the cold wave of January 28-February 3, 1951 .Ecology 32:731-736. ___ , Robert H Williams, Charles C. Davis, & Walton Smith. 1948. Catastrophic mass mortality of marine animals and coin- cident phytoplankton bloom on the west coast of Florida, November 1946 to August 1947. Ecol. Monogr, 18:309-324. Hedgpeth, J. W. 1957. Sandy beaches. Pp. 587-608. In: Treatise on Marine Ecology and Paleoecology. Geol. Soc. Am. Mem. 67. Volume 1 , Ecology. Lowery, G. H., Jr. 1943. Check-list of the mammals of Louisiana and adjacent waters. Occas , Pap. Mus. Zooi La, State (Jniv. 13:113-257. Pearse, H. S., H, J. Humm & G. W. Wharton. 1942. Ecology of sand beaches at Beaufort, North Carolina. Ecol. Mongr. 12:135-190. Gulf Research Reports Volume 6 | Issue 3 January 1979 Notes on the Genus Probythinella Thiele, 1928 (Gastropoda: Hydrobiidae) in the Coastal Waters of the Northern Gulf ofMexico and the Taxonomic Status ofVioscalba louisianae Morrison, 1965 Richard W Heard Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.15 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Heard; R. W. 1979. Notes on the Genus Probythinella Thiele; 1928 (Gastropoda: Hydrobiidae) in the Coastal Waters of the Northern Gulf ofMexico and the Taxonomic Status of Vioscalba louisianae Morrison, 1965. Gulf Research Reports 6 (3): 309-312. Retrieved from http:// aquila.usm.edu/gcr/vol6/iss3/ 15 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(2)usm.edu. Gulf Research Reports, Vol. 6, No. 3, 309-312, 1979. NOTES ON THE GENUS PROBYTHINELLA THIELE, 1928 (GASTROPODA: HYDROBIIDAE) IN THE COASTAL WATERS OF THE NORTHERN GULF OF MEXICO AND THE TAXONOMIC STATUS OF VIOSCALBA LOUISIANAE MORRISON, 1965 RICHARD W. HEARD Gulf Coast Research Laboratory , Ocean Springs , Mississippi 39564 ABSTRACT The gastropod genus Probythinella Thiele, 1928, is considered a senior synonym of Vioscalba Morrison, 1965. Probythinella louisianae (Morrison, 1965) n, comb, tentatively is recognized as a valid species distinct from the closely related P. lacustris (Baker, 1928) and P. prorera Pilsbry, 1953. The eastern range of P. louisianae is extended to Mobile Bay, Alabama. Limited observations on the habitat and TAXONOMY Confusion has existed concerning the taxonomy of the gastropod genera Probythinella Thiele, 1928, and Vioscalba Morrison, 1965, which have been reported from brackish water of the northern Gulf of Mexico. During the past sev- eral years, in conjunction with various benthic and parasi- tologic studies. 1 have collected and observed large numbers of Probythinella from estuarine areas in this region. Using these observations and the existing literature, I have been able to clarify the taxonomic status of the genus Vioscalba and to give an opinion on the specific identity of the northern Gulf populations of Probythinella. Two species of the genus Probythinella Thiele, 1928, have been described; both are known only from North America. Probythinella lacustris (Baker, 1928), a fresh- water species, has been reported from central Canada and from the central United States as far south as Arkansas (Hibbard and Taylor 1960). The second species, P, protera Pilsbry, 1953, was described from “fossil” shells taken from Pleiocene deposits near Tampa Bay, Florida (Pilsbry 1953). Solem (1961) reported a living population of P. protera from estuarine habitats in Lake Pontchartrain, Louisiana, and concluded that other living gastropod species were known from the Pleiocene period and that the phenomenon was not as significant as it would seem. There also is the possibility that Pilsbry’s specimens of P. protera were of recent origin and were not fossil shells. William G. Lyons (personal communication, 1979) indicated that the type locality for P. protera, a dredge-fill area, has a mixture of recent and fossil mollusk shells. Without referring to Solem’ s (1961) study, Morrison (1965) described a new genus and species, Vioscalba louisi- anae. He reported large populations of this gastropod from Lakes Pontchartrain and Borgne, and dead shells from Hope- dale, Louisiana, and Heron Bay, Mississippi. Morrison further stated that V. louisianae and P. protera were closely related but distinct species, and transferred P. protera to the genus Manuscript received September 4, 1979; accepted October 3, 1979. reproduction of P. louisianae are reported. Vioscalba . The name Vioscalba louisianae has been used for this species in subsequent publications (Tarver and Dugas 1973, Dugas, Tarver and Nutwell 1974; Tarver and Savoie 1976; Andrews 1977). Andrews reported V louisianae to be a common brackish-water species along the Texas coast. She listed it under the family Stenothyridae and mentioned that it might be a synonym of V. protera [-Probythinella protera] . 1 have compared my material with published des- criptions of P. lacustris, P. protera and V louisianae . 1 also have examined shells o iP. lacustris from Ohio in the collec- tions of the Florida State Museum. Based on these observa- tions, especially the similarity of the male copnlatory organs (verges) and the shells, I conclude that the genus Vioscalba Morrison, 1965, definitely is a junior synonym of Proby- thinella Thiele, 1928, The specific designation for living populations of Proby- thinella occurring in estuarine areas of the northern Gulf is more difficult to determine with certainty. Morrison (1965) distinguished P. protera from V. louisianae as follows: “V. protera has a more abruptly truncated spire; the body whorl and the penultimate whorl of protera are flatter toward the suture; in contrast all whorls of louisianae are more regularly rounded from suture to suture. The shells of louisianae appear markedly more obese than the specimens of pro few seen.” Solem (1961) reported that P. protera appeared to be closely related to the freshwater species, P. lacustris, which has its earliest known occurrences in the late Pleisto- cene (Hibbard and Taylor 1960). Considerable variation in shell morphology of P. lacustris had been reported, and this variation, coupled with other factors, created considerable taxonomic confusion. Hibbard and Taylor (1960) clarified the taxonomy of P , lacustris , listing its synonyms and sum- marizing what was known of its biology. Concerning intra- specific variation they stated: “There is no warrant for taxo- nomic recognition of the known variation within Pro by thin- ella lacustris Solem (1961) also noted considerable varia- tion in the shell morphology within the population oi Proby- thinella protera from Lake Pontchartrain and stated that the constricted aperture of P. protera was the most consistent 309 310 Heard difference between the two species. He further suggested that the constricted aperture of P. protera and two other gastropods, Texadina sphinc to stoma Abbott and Ladd, 195 1 , and Amphithalamus dy status Pilsbry and McGinty, 1950, might be “a convergent response to some unknown ecological factor in the Gulf Coast estuarine environment, since it has occurred in [their] three distinct lineages.” Shell variation within the northern Gulf populations of Probythinella is great enough to make them nearly, if not completely, indistinguishable from the fossil shells of P. protera, as well as some of the shell forms of P. lacustris. Figure 1 illustrates two shells of Probythmella from Lake Pontchartrain showing differences in their spires and aper tures. The soft parts are illustrated in Figure 2, which shows the pigmentation of the mantle and visceral mass (A) and two aspects of the male copulatory organ, the verge (B, C), If P. protera sensu Pilsbry, 1951, proves not to be a fossil form and extant populations are found in the Tampa Bay area, a careful comparison of the verge, radula, pigmentation pattern, and other morphological features of the soft body parts of this species with those of the northern Gulf popula- tions of Probythinella will be needed to determine if they are conspecilic or distinct species. If, on the other hand, P. protera is a true fossil species, its specific status in relation to P. lacustris and the brackish water forms from the northern Gulf of Mexico becomes largely a matter of taxonomic conjecture. Based on the information available, three taxonomic options exist concerning the specific name for the popula- tions of Probythinella occurring in the northern Gulf : ( 1 ) all known specimens of Probythinella, including fossil and brackish-water forms, are variants or ecotypes of a single species —P. lacustris, (I) all fossil and living specimens of the genus from coastal areas of the Gulf of Mexico are P.pro tera; (3) there are three distinct species presently known in North America-/? lacustris (Baker, 1928);/ ) . protera Pilsbry, 1953; and P. louisianae (Morrison, 1965). Pending additional collections and biological studies, 1 accept the third option and recognize Probythinella louisianae (Morrison, 1965) n. comb, as a distinct species, which is conspecific with P. protera sensu Solem, 1961 . If living specimens of Probythin- ella with constricted apertures characteristic of P . protera and P. louisianae should be collected in brackish-water areas along the west coast of Florida near the Tampa Bay area, then option 2, or Solem’s (1961) designation for the northern Gulf specimens as ‘P, protera,’' will probably be correct, with P. louisianae becoming its junior synonym. Detailed morphologic, ecologic, physiologic, and behavioral com- parisons of P. lacustris and P. louisianae will be needed to A B Figure 1. Probythinella louisianae (Morrison, 1965) from Lake Pontchartrain, Louisiana; shells A and B demonstrate morphological variation from same population; specimen within box represents life size of adult snail. Short Communications 311 Figure 2. Probythinella iouisianae (Morrison, 1%5) from Lake Pontchartiain, Louisiana; A-adult female, dorsal aspect (shell removed), showing pigmentation on mantle and visceral mass; B -adult male, dorsal aspect (shell removed); C-adult male, frontal aspect; a-verge (penis), b-single lobe on convex margin of verge, c-edge of mantle, d-visceral mass, e-tentacles, f-snout, g-foot, h-operculum, i-opening of sperm duct (vas deferens) at tip of verge. refute or validate option 1. Cross-breeding experiments between the two species would be especially useful. BIOLOGICAL NOTES I have made some limited observations on the distribu- tion, ecology, and reproduction of P. Iouisianae , which are included here as a possible stimulus for futher study. I have found P. Iouisianae in several locations east of its published range-in Mississippi (St. Louis Bay, Back Bay of Biloxi, Davis, Simmons, and Heron bayous, and the West Pascagoula River) and in Alabama (mouth of East Fowl River and Mobile Bay). The Alabama record extends the known eastern range of P. Iouisianae approximately 113 kilometers. My attempts to Find this species in a number of areas along the eastern Alabama and western Florida coasts, including Escambia, Appaiachicola and Tampa bays, were unsuccess- ful; however, my collections were limited, leaving the pos- sibility that Probythinella may still occur in these areas. Specimens of P. Iouisianae collected during this study were all from areas with low salinities, usually less than 10 ppt and in some instances approaching freshwater condi- tions. Living specimens were always found subtidally, usually in water depths greater than a meter. The largest concentra- tions occurred on Fine sand-silt bottoms^ut some specimens were occasionally found in muddy areas. My observations of specimens maintained in the laboratory indicate that P. Iouisianae usually occurs partly covered by the bottom sediment or just under it. As the snails move through the sediment they leave distinct tracks. I never observed speci- mens of P. Iouisianae penetrating deeper than 3 to 4 mm into the sediment. A number of other invertebrates occurred in association with P, Iouisianae, including Texadina sphinc- tostoma Abbott and Ladd, 1951; Neritina reclivata (Say, 1822); Rangia cuneata (Gray, 1831 )\Mulinia sp .\Macoma mitchelli Dali, 1 895 \Mytilopsis leucophaeta (Conrad , 1831); Corophium lacustre Vanhoffen, 1811; Hargaria rapax (Hargar, 1879); Hypaniola florida (Hartman, 1951); Streb- lospio benedicti Webster, 1879; and chironomid midge larvae. The smooth, cream-colored shells of P. Iouisianae were often fouled with reddish-brown or rust-colored encrustations. These encrustations appeared to be due, at least in part, to small invertebrate (turbellarian?) egg cases and associated microflora. While maintaining P. Iouisianae in glass culture bowls in the laboratory, I observed female snails depositing egg cap- sules on hard surfaces, including pieces of dead shell and wood, the shells of other/*. Iouisianae . and the bottoms and sides of the culture bowls. Each newly deposited egg capsule contained a single egg in an early stage of cleavage. When viewed dorsally, the capsules were circular with diameters of 0.5 to 0.6 mm. In lateral aspect, the capsules were dome- shaped with Rattened proximal surfaces attached to the sub- strate by a mucoid adhesive. After 8 to 12 days of develop- ment, a small juvenile snail with fully formed protoconch emerges from each capsule. There is no planktonic veliger stage, and the newly hatched snails crawl about on the bottom sediments and begin feeding. Probythinella Iouisianae can occur in relatively large numbers, often exceeding 1,000 per square meter, but little is known about its bionomics. Morrison (1965) reported that the snails are eaten by wild ducks; however, there are no other published data on their impact on the estuarine food chain as either consumers or prey for other organisms. It is probable that P. Iouisianae and its even more numerous gastropod associate T. sphinctostoma play an important role in the reworking and enrichment of the sediments on which 312 HEARD they occur. My observations indicate that both these snails are deposit feeders. Individuals of either species, despite their small size (2.5 to 3.5 mm shell length), consume a consider- able amount of bottom material and daily produce large num- bers of fecal pellets. The ecological and nutritional import- ance of fecal material from estuarine and marine invertebrates and its probable role in the food web have been discussed and documented by Newell (1965), Johannesand Satomi(1966), Frankenberg, Coles, and Johannes (1967), Frankenberg and Smith (1967), and Kracuter (1976). Since/', lauisianae and T. sphinctostoma often occur in great numbers over large areas of bay bottom, studies are needed of their nutritional and overall ecological impact on northern Gulf estuarine systems. ACKNOWLEDGMENTS This study was supported in part by a grant entitled “Helminths of the Gulf of Mexico” from the State of Mississippi to R. M, Overstreet, and by a contract (No. DACN— 29— 77— C-02 53) from the U.S. Army Corps of Engineers to the Center for Wetland Resources, Louisiana State University. Appreciation is extended to B. Heard for preparing the illustrations, and to R. M. Overstreet and Walter B. Sikora for their constructive comments and sug- gestions on the manuscript, Fred G. Thompson kindly allowed me to examine specimens of P. lacustris in the collections of the Florida State Museum. REFERENCES CITED Andrews, J. 1977. Shells and Shores of Texas. Univ. of Texas Press, Austin. 365 pp. Dugas, R J., J. W, Tarver & L. S. Nut well. 1974. The mollusk com- munities of Lakes Pontchartrain and Maurepas, Louisiana. La. Wild!, Fish. Tech. Bull. 10:1-13. Frankenberg, D., S. L. Coles &, R. E. Johannes. 1967. The potential trophic significance of Callianassa major fecal pellets. Limnol. Oceanogr. 12(1): 1 1 3-120. & K. L. Smith. 1967. Coprophagy in marine animals. Limnol. Oceanogr. 1 2(3);443 -450. Hibbard, C. W. & D. W, Taylor. 1960. Two late Pleistocene faunas from southwestern Kansas. Contrib, Mus. Paleontol. Univ. Mich. 16(1). 1-223, Johannes, R. E. & M. Satomi. 1966. Composition and nutritive value of fecal pellets of a marine crustacean. Limnol. Oceanogr. 11(2): 191-197. Kraeuter, J. N, 1976. Biodeposition by salt-marsh invertebrates. Mar. Biol. 35:215- 223. Morrison, J. P.E. 1965. New brackish water mollusks from Louisiana. Proc. Biol. Soc. Wash. 7R(27):217-224. Newell, R. 1965. The role ordettitus in the nutrition of two marine deposit feeders, the prosobranch Hydrobia ulvae and the bivalve Macoma hall h tea. Proc Zool. Soc Lond. 144:25-45. Pilsbry, H, A 1953 Plieocene Mollusca of southern Florida, with special reference to those from North Saint Petersburg: Vitrinell- idae and fresh water mollusks. Monogr. Acad, Nai. Sci. Phila. 8:41 1-447, Solern, A 1961. Hydrobiid snails from Lake Pontchartrain, Louisiana. Nauiilus 74(4) :1 57-160. Tarver, J. \V. & R. J. Dugas. 1973. A study of the clam, Rangin cun. eata, in Lake Pontchartrain and Lake Maurepas, Louisiana. La. Wildl. Fish . Comm. Tech. Bull. 5:1-87. & L. B. Savoie, 1976. An inventory and study of the Lake Pont chart rain- Lake Maurepas estuarine complex. Phase II- Biology. La. Wildl. Fish. Comm. Tech Bull. 19:7-99. Gulf Research Reports Volume 6 | Issue 3 January 1979 First Record of a Bloom of Gonyaulax monilata in Coastal Waters of Mississippi Harriet M. Perry Gulf Coast Research Laboratory Kenneth C. Stuck Gulf Coast Research Laboratory Harold D. Howse Gulf Coast Research Laboratory DOI: 10.18785/grr.0603.16 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Perry, H. M., K. C. Stuck and H. D. Howse. 1979. First Record of a Bloom of Gonyaulax monilata in Coastal Waters of Mississippi. Gulf Research Reports 6 (3): 313-316. Retrieved from http:// aquila.usm.edu/gcr/vol6/iss3/ 16 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(2)usm.edu. Gulf Research Reports , Vol. 6, No. 3, 313-316, 1979. FIRST RECORD OF A BLOOM OF GONYAULAX MOM LATA IN COASTAL WATERS OF MISSISSIPPI HARRIET M. PERRY, KENNETH C. STUCK AND HAROLD D. HOWSE Fisheries Research and Development, and Microscopy Sections, Gulf Coast Research Laboratory , Ocean Springs, Mississippi 39564 ABSTRACT Data are presented on a bloom of the toxic dinottagcllate Gonyaulax monilata in coastal waters of Florida, Alabama, Mississippi and Louisiana. This paper documents the first record of a bloom of this species in Mississippi Sound and adjacent Gulf of Mexico. INTRODUCTION Red tides resulting from toxic dino flagellate blooms are a common phenomenon in the coastal waters of Florida and Texas. Periodic!) looms of the unarmored dinoilagellate Gymnodinium breve have created both economic hardships and public health problems for residents of the Florida west coast for over 100 years. Gymnodinium breve tides occur most frequently from Anclote Keys off Tarpon Springs to the Florida Keys (Joyce and Roberts 1 975). Toxic red tides in northern Gulf waters more often arc associated with blooms oi the armored dinoflagellate Gonyaulax monilata. Howell (1953) first described G . monilata and found it was associated with discolored water and small fish kills on the east coast of Florida near Melbourne. Me also identified this dinoflagellate as the causative organism for the red water and fish kill reported by Connell and Cross (1950) from Offats Bayou, Galveston, Texas (Wardle et a). 1975). Gatesand Wilson ( 1960), Marvin (1965), Marvin and Proctor (1965), Ray and Aldrich (1966) and Wardle et al. (1975) have since documented the occurrence of summer blooms of G . monilata in the Galveston area. Williams and Ingle (1972) studied a G. monilata bloom associated with a fish kill from the west coast of Florida, establishing the first record of its occurrence in offshore waters. Red tides caused by toxic dinoflagellate blooms have not been reported from Mississippi Sound, although phyto- plankton blooms causing discolored waters are a frequent occurrence during warmer months. The senior author observed extensive blooms of the blue-green alga Oscillatoria erythraeum in waters near the offshore barrier islands in August 1974 and July 1976. Small localized blooms along mainland beaches may be responsible for the “jubilees’' that occur periodically (Gunter, personal communication). MATERIALS AND METHODS Aerial surveys were made on August 14, 17, 21, 29 and on September 25, 1979, to monitor the bloom and map the Manuscript received October 1 1 , 1979; accepted October 15, 1979. affected areas in Mississippi waters. A number of investiga- tions were conducted by boat to collect samples of the organism and to check for fish kills. Cell counts were made from dip samples taken in areas of intense water discolor- ation. After measuring the volume of the sample, it was gently mixed and an aliquot withdrawn. The aliquot was placed in a settling chamber for a period of 24 hours. The organisms were identified and counts made in 50 fields (chosen randomly) at a magnification of 250X using a Zeiss inverted microscope equipped with phase contrast. Deter- mination of numbers of organisms per liter was made using the following formula: cells/liter = number f t0 * a ^ area ~ir concentr ated volume counted b reacovere ^lL aliquot volume , liters filtered Observations by personnel of the National Marine Fish- eries Service (NMFS) Laboratory in Pascagoula, Mississippi, and reports from local fishermen were also recorded. RESULTS AND DISCUSSION Reports of red water in the vicinity of Ship Island Pass were received by Gulf Coast Research Laboratory personnel on 8 August 1979. Analysis of samples taken on 9 August confirmed the presence of large numbers of the dinoflagellate G. monilata . Gonyaulax monilata is a small, sub-spherical armored dinoflagellate that appears somewhat llattened through the antero-posterior axis. It characteristically forms chains of up to 40 cells in length (Figure 1), but also may exist as single cells (Howell 1953). The incidence of Jong chains in a bloom serves as an index of the growth phase (Aldrich et al. 1967). Rapidly increasing populations have the highest per- centages of individuals in long chains, while short chains of two and four cells are more common during the stages of maximum and declining numbers. The initial aerial survey on 14 August located extensive 313 314 PLRRY I-T AL. Figure 1. A photomicrograph of Gonyaulax monilata showing the long chain structure characteristic of this dinoflagellate. Normarski differ- ential interference contrast, X 210. areas of discolored water in the western sector of Mississippi Sound and adjacent Gulf of Mexico (Figure 2). Heaviest concentrations of the organism were found between Cat and Ship islands. Long streaks of red water were noted south of these islands extending into upper Chandeleur Sound, Louisiana. Large patches of discolored water were observed in Mississippi Sound to the north of Cat Island reaching to within 3 miles of the mainland in the Pass Christian area. Smaller patches occurred south of Horn and Petit Bois islands and near Round Island, south of Pascagoula. A similar pattern of distribution was noted on 17 August, although the water discoloration was less intense. On 21 August, the bloom appeared to be dissipating (Figure 3). The long streaks of red water south of Cat and Ship islands had virtually disappeared and the patches occurring north of Cat Island were diminished in si?.e, A few streaks of intense water discoloration were observed to the east of Grand Island (Halfmoon Island) and a semicircular patch was noted between Cat Island and Isle au Pitre, Louisiana. By 29 August, only a few patches of red water were sighted north of Cat Island and near Grand Island. Visual observa- tions on 30 August by NMFS personnel aboard the R/V OREGON 11 indicated that the bloom still persisted in off- shore waters in the area of 29° 1 5' N, 88°40' W. No areas of water discoloration were observed on the final survey on 25 September. The heavy seas and winds brought about by Hurricane Frederic (which struck the Mississippi/Aiabama coast on 1 1 - 12 September) appeared to have completely dissipated the bloom. The initial outbreak of the G. monilata bloom followed a period of lowered salinities in Mississippi Sound due to heavy rains associated with Hurricane Bob (II July) and Tropical Storm Claudette (23 July). Surface temperatures and salinities during the bloom ranged from 30.0 to 30.8°C and 24.0 to 26.0 ppt, respectively. Extensive blooms of G. monilata occurred in Florida and Alabama concurrent with the Mississippi outbreak. Large areas of discolored water were reported in the Pensacola Bay estuary (William Young. Florida Department of Envir- onmental Regulation fFDERJ persona! communication) and in lower Mobile Bay and adjacent offshore waters (Walter Tatum, Alabama Department of Natural Resources, personal communication). Personnel of the FDER monitored the bloom in Pensacola Bay from 2 August until 24 August. A maximum cell count of 3.18 x 10 7 cells/liter was taken on 15 August. Water temperature was 28.0°C and salinity 14.0 ppt at the time the above sample was collected. Small Short Communications 315 8/14/79 Figure 2. Areal distribution of bloom on 14 August 1979. 8/21/79 Figure 3. Areal distribution of bloom on 21 August 1979. 316 Perry et al. fish kills were associated with the bloorn in both Florida and Alabama. A maximum cell count of 1.65 x 10 7 cells/liter was made from a dip sample in heavily discolored water south- west of Cat Island, Mississippi, on 22 August. Although our cell counts were high enough to cause death in marine organisms (Wardle et al. 1975), no mortality was observed associated with the bloom in Mississippi. Because the bloom occurred in open waters and was patchy in its distribution, schools of fish evidently were able to avoid it. ACKNOWLEDGMENTS The authors thank Dr. R. B. Channel of Vanderbilt Uni- versity for confirmation of identification of G. monilata and Chris Modert of Gulf Coast Research Laboratory (GCRL) who analyzed the plankton samples. For their help in field observations, appreciation is extended to R. M. Overstreet, Kay Richards, Kenneth Melvin, Myron Loman, Thomas Van Devender and James Warren, all of GCRL; to Bennie Rohr of the NMFS, and to the personnel of the Gulf Islands National Seashore, National Park Service. REFERENCES CITED Aldrich, D. V., S. M. Ray & W. B. Wilson. 1967. Gonyaulax monilata: Population growth and development of toxicity in cultures. J. Protozoal. 14(4 ):6 36 639. Connell, C. II. &. J. B. Cross. 1950. Mass mortality of fish associated with the protozoan Gonyaulax in the Gulf of Mexico. Science 1 12(2909):359-363. Gates, J. A. &. W. B. Wilson. 1960. The toxicity of Gonyaulax monilata Howell to Mugil cephalus. Limnol. Oceanogra. 5(2): 171 -174. Howell, J. F. 1953. Gonyaulax monilata. sp. nov., the causative dino- flagellale of a red tide on the east coast of Florida in August - September, 195L Trans. Am, Microsc. Soc. 72(2): ) 53“ 156. Joyce, E. A. &. B. S. Roberts. 1975. Florida Department of Natural Resources red tide research program. Pp. 95-103 in Proc. 1st Intend. Conf Toxic Dinoflagella te Blooms. Massachusetts Science and Technology Foundation, Wakefield, Massachusetts. Marvin, K, T. 1965. Operation and maintenance of salt-water labor- atories. U.S. Fish Wildl. Serv. Circ. 230:84-86. & R. R. Proctor, 1965. Description of salt-water labora- tories, U.S. Fish Wildl. Serv. Circ. 230:94-102. Ray, S M. & D. V, Aldrich. 1966. Ecological interactions of toxic dinoflagellales and molluscs in the Gulf of Mexico. Pp. 75-83 in F.E. Russell and P. R. Saunders (eds ,), Animal Toxins. Pergatnon Press, New York. Wardle, W. J., S. M. Ray & A, S, Aldrich. 1975. Mortality of marine organisms associated with offshore summer blooms of the toxic dinofiagellate Gonyaulax monilata Howell al Galveston, Texas. Pp. 257-263 in Proc. 1st Intern!. Conf. Toxic Dino flagellate Blooms. Massachusetts Science and Technology Foundation, Wakefield, Massachusetts. Williams, J. & R. M. Ingle. 1972. Ecological notes on Gonyaulax monilata (Dinophyecae) blooms along the west coast of Florida. Fla. Dep . Nat. Resour. Mar. Res. Lab,, leaf 7. Ser. Vol. 1, Pt. 1, No. 5, 12 pp.