Biological Services Program FWS/OBS-81/04 October 1981 Proceedings of the National Symposium on Freshwater Inflow to Estuaries VOLUME Fish and Wildlife Service U.S. Department of the Interior The Biological Services Program was established within the U.S. Fish and Wildlife Service to supply scientific information and methodologies on key environmental issues that impact fish and wildlife resources and their supporting ecosystems. The mission of the program is as follows: • To strengthen the Fish and Wildlife Service in its role as a primary source of information on national fish and wild- life resources, particularly in respect to environmental impact assessment. • To gather, analyze, and present information that will aid decisionmakers in the identification and resolution of problems associated with major changes in land and water use. • To provide better ecological information and evaluation for Department of the Interior development programs, such as those relating to energy development. Information developed by the Biological Services Program is intended for use in the planning and decisionmaking process to prevent or minimize the impact of development on fish and wildlife. Research activities and technical assistance services are based on an analysis of the issues, a determination of the decisionmakers involved and their information needs, and an evaluation of the state of the art to identify information gaps and to determine priorities. This is a strategy that will ensure that the products produced and disseminated are timely and useful. Projects have been initiated in the following areas: coal extraction and conversion; power plants; geothermal , mineral and oil shale develop- ment; water resource analysis, including stream alterations and western water allocation; coastal ecosystems and Outer Continental Shelf develop- ment; and systems inventory, including National Wetland Inventory, habitat classification and analysis, and information transfer. The Biological Services Program consists of the Office of Biological Services in Washington, D.C., which is responsible for overall planning and management; National Teams, which provide the Program's central scientific and technical expertise and arrange for contracting bioloqical services studies with states, universities, consulting firms, and others; Regional Staffs, who provide a link to problems at the operating level; and staffs at certain Fish and Wildlife Service research facilities, who conduct in-house research studies. FWS/OBS-81/04 October 1981 PROCEEDINGS OF THE NATIONAL SYMPOSIUM ON FRESHWATER INFLOW TO ESTUARIES Volume I Edited by Ralph D. Cross and Donald L. Williams University of Southern Mississippi Southern Station, Box 5051 Hattiesburg, Mississippi 39401 Project Officer Norman G. Benson National Coastal Ecosystems Team Fish and Wildlife Service U.S. Department of the Interior NASA - Slidell Computer Complex Slidell, Louisiana 70458 Prepared for Coastal Ecosystems Project Office of Biological Services Fish and Wildlife Service U.S. Department of the Interior Washington, D.C. 20240 Disclaimer The findings in this report are not to be construed as an official U.S. Fish and Wildlife Service position unless so designated by other authorized docu- ments. This publication should be cited as follows: Cross, R., and D. Williams, eds. 1981. Proceedings of the National Symposium on Freshwater Inflow to Estuaries. U.S. Fish and Wildlife Service, Office of Biological Services. FWS/OBS-81/04 . 2 Vol. ii NATIONAL SYMPOSIUM ON FRESHWATER INFLOW TO ESTUARIES PREFACE The First National Symposium on Freshwater Inflow to Estuaries spon- sored by the U.S. Fish and Wildlife Service, was held in San Antonio, Texas on 9-12 September 1980. The Symposium focused attention on the importance of estuarine ecosystems to our Nation and their dependency on freshwater inflows. Estuaries have been degraded in many coastal areas and much of the documented damage has been attributed to alteration and re- ductions of freshwater inflow. The symposium was organized to accomplish the following objectives: 1. Identify the issue of estuarine freshwater inflow requirements as a National Environmental Problem. 2. Describe some values of estuarine ecosystems to the Nation for food, recreation, and fish and wildlife habi- tats . 3. Review models or method- ologies for predicting the effects of altering freshwater inflow on estuarine ecosystem functions, processes, and pro- duction. 4. Develop recommendations that bring the freshwater in- flow needs of estuaries more effectively into inland and coastal planning. Efforts were made to include participation of government leaders, engineers, ecologists, lawyers, econ- omists, hydrologists , and others in- terested in estuaries. We accom- plished all of the stated objectives to some degree. These Proceedings are an initial effort to develop a data base and to bring freshwater inflow into local, state, regional and federal planning and management processes. Participants emphasized that there was much concern for pro- tecting and restoring water needs of estuaries. Lack of planning was attributed to inadequate baseline data and models or methods of apply- ing the data. The Proceedings are organized by chapters that closely follow the Symposium's sessions. The discussion and some of the plen- ary presentations were edited from recorded material. Comprehensive and effective planning for freshwater inflow to estuaries requires that all inland land- and water-use decisions with- in a watershed that empties into the ocean should be made with a clear understanding of the conse- quences of these decisions on estu- arine ecosystems. Although this goal will be difficult to implement, it ^.s based upon the widely recognized eco- logical fact that all the ecosystems within a watershed are tied together. Several recommendations to pro- tect and restore estuarine ecosystems were developed from plenary sessions, technical papers, and discussions. These recommendations will be for- warded to agencies responsible for their implementation. Estuaries probably have been affected more by development and industry than any other ecosystem in our Nation because many of our largest cities are located either on major rivers providing fresh water to estuaries or on estuaries themselves. Estuaries are one of the best ecosys- tems for monitoring our success in integrating commercial development and environmental protection. Norman G. Benson Paul F. Fore Co-Chairmen Any questions or requests for this publication should be directed to: Information Transfer Specialist National Coastal Ecosystems Team U.S. Fish and Wildlife Service NASA/Slidell Computer Complex 1010 Gause Blvd. Slidell, Louisiana 70458 or Information Transfer Spceialist Office of Environment, Region 2 U.S. Fish and Wildlife Service Box 1306 Albuquerque, New Mexico 87103 ACKNOWLEDGMENTS The goal, objectives, and scope of the Symposium were developed by a steering committee consisting of the following: Norman G. Benson, U. S. Fish and Wildlife Service (FWS) , Co-chairman Paul Fore, FWS, Co-chairman James Barkuloo, FWS Keith Bayha, FWS Bert Brun, FWS John Byrne, FWS Ralph Cross, University of Southern Mississippi Nicholas Funicelli, FWS B.D. King, FWS Steven Goodbred, FWS Robert Hayden, FWS Joseph Kathrein, FWS William Lindall, National Marine Fisheries Service Norval Netsch, FWS Ted Robinson, U.S. Army Corps of Engineers Richard Wade, FWS (retired) Myron Webb, Symposium Coordina- tor, University of Southern Missis- sippi, handled the administrative work. Session chairmen introduced speakers, directed discussion, and assisted in editing the papers. Those session chairmen that were not on the steering committee were: Robert Stewart, FWS John Clark, Conservation Foundation Gordon Thayer, National Marine Fisheries Service Gilbert Radonski, Sport Fishing Institute Robert Livingston, Florida State University Charles Caillouet, National Marine Fisheries Service William Perret, Louisiana Wildlife and Fisheries Department Rezneat Darnell, Texas A&M University Emmet Gloyna, U.S. Water and Power Resource Service Wiley Kitchens, FWS Gerald Johns, California State Water Resources Board Carroll Cordes, FWS The Sport Fishery Research Foundation and the Environmental Quality Committee of the American Fishing Tackle Manufacturers Asso- ciation provided travel funds for some invited speakers. IV Preparation and publication of Fish and Wildlife Service, Coastal the Proceedings were supported by Ecosystems Project, the U.S. Department of the Interior, TABLE OF CONTENTS VOLUME I PREFACE iii ACKNOWLEDGEMENTS iv PLENARY SESSION: ESTUARIES AND FRESHWATER INFLOW 1 Introduction Robert Stewart 2 Welcoming Address Jerry L . Stegman 3 Keynote Address: How Congress Views Estuaries Keith Ozmore 5 Overview of U.S. Water Resources Planning, Policies, and Laws That Affect Coastal Areas Gerald Seinwell 10 Role of the National Marine Fisheries Service in the Protection of Freshwater Inflow Estuaries James W. Rote 18 Freshwater Inflows and Fish and Wildlife Service Operations Michael Spear 23 Freshwater Inputs and Estuarine Productivity Scott W. Nixon 31 POLICIES AND PROBLEMS IN DEALING WITH FRESHWATER INFLOW TO ESTUARIES 58 Introduction John Clark 59 Freshwater Inflow and Chesapeake Bay Mark Bundy 60 Problems of Freshwater Inflow Planning in California Ken Collins 62 Management of Freshwater Inflow to Estuaries: A Lawyer's Perspective James B. Tripp 65 Water Management on the Columbia River David Kent 79 VI Freshwater Inflow and Water Management in California Gerald Johns 84 Freshwater Inflow Planning in Texas Herbert Grubb 88 Federal and State Coastal Zone Management Efforts Directed at Estuaries and Freshwater Inflow Richard B. Mieremet 96 Corps of Engineers Policies on Freshwater Inflow Walter B. Gallaher 104 Banquet Address Honorable Robert L. Herbst 109 CHAPTER 1: FRESHWATER INFLOW STUDIES ALONG THE MID- AND NORTH 113 ATLANTIC COAST Chesapeake Bay Low Freshwater Inflow Study Alfred E. Robinson 114 Aspects of Impact Assessment on Low Freshwater Inflows to Chesapeake Bay G. Bradford Shea et al. 128 Freshwater Influences on Striped Bass Population Dynamics J. A. Mihursky et al. 149 Effects of Freshwater Flow on Salinity and Phytoplankton Biomass in the Lower Hudson Estuary P. J. Neale et al. 168 Assessment Methodologies for Freshwater Inflows to Chesapeake Bay C. John Klein et al. 185 CHAPTER 2: RESTORATION OF FRESHWATER INFLOW TO AN ESTUARY 200 IN CONJUNCTION WITH URBAN DEVELOPMENT Historical Background and Overview of Plan for Restoring Freshwater Inflow to an Estuary in Conjunc- tion with Urban Development Paul Larsen 201 vii Floral Description of Marco Shores Development Site Eric Heald 212 Meromixis in Coastal Zone Excavation Charles M. Courtney 219 Surface Water Flow from South Florida Wetland Area J. van de Kreeke and Ernest Daddio 232 Water Budget and Projected Water Quality in Proposed Man-Made Lakes Near Estuarys in the Marco Island Area, Florida Wayne C. Huber and Patrick L. Brezonik 241 The Ground Water Flow System in the Vicinity of Marco Island, Florida Vincent P. Amy 252 Summary of Papers Describing Restoration of Freshwater Inflow to an 264 Estuary in Conjunction with Urban Development CHAPTER 3: FISHERIES MANAGEMENT AND FRESHWATER INFLOW 268 The Effects of Freshwater Discharges on Sport Fish- ing Catch Rates in the St. Lucie Estuary, Martin County, Florida .Eleanor Van Os et al. 269 Effects of Freshwater Runoff on Fishes Occupying the Freshwater and Estuarine Coastal Watersheds of North Carolina Frank J. Schwartz 282 CHAPTER 4: FLOOD PLAINS AND ESTUARINE PRODUCTIVITY: ENERGY TRANSPORT, FRESHWATER RUNOFF, AND BIOLOGICAL RESPONSE 295 Variation in Freshwater Inflow and Changes in a Subtropical Estuarine Fish Community .Thomas H. Fraser 296 vm River-Derived Input of Detritus into the Apalachicola Estuary Robert J. Livingston 320 CHAPTER 5: MISSISSIPPI RIVER DELTA FRESHWATER INFLOW REHABILITATION 333 Flow Regime and Sediment Load Affected by Alterations of the Mississippi River J. R. Tuttle and A.J. Combe, III 334 Atchafalaya Delta: Subaerial Development, Environmental Implications and Resource Potential Robert Cunningham 349 Freshwater Introduction into Louisiana Coastal Areas John C. Weber and Robert A. Buisson Jr. 366 Biological Considerations Related to Freshwater Introduction in Coastal Louisiana Dennis L. Chew and Frank J. Cali 376 Effects of Wetland Changes on the Fish and Wildlife Resources of Coastal Louisiana David W. Fruge 387 CHAPTER 6: FISHERIES MANAGEMENT AND FRESHWATER INFLOW 402 A New Approach to Determining the Quantitative Relation- ship Between Fishery Pro- duction and the Flow of Freshwater to Estuaries .Joan Browder and Donald Moore 403 Texas Shrimp Fisheries and Freshwater Inflow .Ralph Rayburn 431 IX An Evaluation of Aquatic Life Found at Four Hydraulic Scour Sites in the Columbia River Estuary Selected for Potential Sediment Deposition. .Joseph T. Durkin et al. 436 CHAPTER 7: FRESHWATER INFLOW STUDIES IN SOUTHERN TEXAS ESTUARIES 453 The Effects of Freshwater Inflow on Salinity and Zooplankton Populations at Four Stations in the Nueces-Corpus Christi and Copano-Aransas Bay Systems, Texas from October 1972-May 1975 Richard D. Kalke 454 Nutrient Flux Between the Nueces Deltaic Marsh and the Nueces Estuary on the Texas Gulf Coast D. P. Wilcox and W. M. Childress 472 Estuarine Benthic Community Dynamics Related to Fresh- water Inflow to the Corpus Christi Bay Estuary R. Warren Flint and Steve C. Rabalais 489 The Effects of Floods on the Zooplankton Assemblage of San Antonio Bay, Texas, During 1972 and 1973 Geoffrey A. Matthews 509 VOLUME II CHAPTER 8: EFFECTS AND MEASUREMENT OF FRESHWATER INFLOW The Influence of Salinity Transition on Benthic Nutrient Regeneration in Estuaries , Randy E. Edwards Monitoring Freshwater Inflow to Estuaries by Remote Sensing Robert W. Johnson and Bruce M. Kendall 17 Concentration, Extent, and Duration of Salinity Intrusion into the Columbia River Estuary September-October, 1977-1978.... Robert J. McConnell et al. 41 CHAPTER 9: FRESHWATER INFLOWS AND THE SAN FRANCISCO BAY COMPLEX 54 The Nutritional Significance of the Distribution of Suspended Particulate Material in the Upper San Francisco Bay- Estuary William R. Barclay and Allen W. Knight 55 Effects of Freshwater Flow on Fishery Resources in the Sacramento-San Joaquin Estuary Perry L. Herrgesell et al. 71 Influences of Freshwater Inflow on Chinook Salmon (Oncorhynchus tshawytscha) in the Sacramento- San Joaquin Estuary Martin A. Kjelson et al. 88 CHAPTER 10: GULF OF MEXICO FRESHWATER INFLOW EFFECTS 109 Some Effects of Fresh Water on the Atchafalaya Bay System H. Dickson Hoese 110 Freshwater Inflow and Salt Water Barriers for Management of Coastal Wildlife and Plants in Louisiana Robert H. Chabreck 125 Establishment of Controlled Freshwater Diversions of the Mississippi River into the Louisiana Coastal Zone Marc E. Crandall and Joel L. Lindsey I39 Review of Estuarine-Related Projects by the Gulf of Mexico Fishery Management Council ,Vito J. Blomo 147 XI Values of Ecological Charac- terization Studies to Assess Effects of Freshwater Inflow to Estuaries James B. Johnston and Norman G. Benson 155 CHAPTER 11: REHABILITATION OF ESTUARIES THROUGH REINTRODUCTION OF FRESHWATER INFLOW 165 The Mouth of the Colorado River Project an Economic Development - Environmental Enhancement Project Joseph C. Trahan 166 Effects of Alterations of Freshwater Inflows into Matagorda Bay, Texas Neal E. Armstrong and George H. Ward, Jr. 179 Sediment--Asset or Liability Johannes L. van Beek and Klaus Meyer-Arendt 197 Loss of Colorado River Inflows to Matagorda Bay, Texas and Efforts for Restoration William J. Sheffield and Murray T. Walton 216 CHAPTER 12: FRESHWATER INFLOW PLANNING: PART I 230 Overview of Freshwater Inflow Depletions Keith Bayha 231 Management, Planning, and Organization in Initiating, Supporting and Coordinating an Ongoing Freshwater Diversion Proiect David J. Etzold 248 An Overview of Texas Law, Policy, and Agency Actions Concerning Estuarine Inflow Murray T. Walton 255 Freshwater Inflow to the Columbia River Estuary: A Northwest Regional Management Issue David H. Kent 270 Xll Scientific Progress and Deteriorating Ecosystems San Francisco Bay and the 1970' s Phillip A. Meyer and William T. Davoren 277 CHAPTER 13: FUNDAMENTAL FACTORS INFLUENCING FRESHWATER INFLOW TO ESTUARIES 288 The River Continuum: A Theoretical Construct for Analysis of River Ecosystems .Robin L. Vannote 289 Freshwater Inflow to Estuaries, Short and Long-Term Perspectives. .Robert B. Biggs 305 Precipitation Trends and Variability in the Vicinity of the Northwest Gulf Coast: 1900-1980 Jim Norwine 322 Rainfall-Related Trends in the Structure of a Fish- Crustacean Community in Texas' Galveston Bay System. .Darlene R. Johnson et al. 335 Historical Overview of Freshwater Inflow and Sewage Treatment Plant Discharges to the Potomac River Estuary with Resultant Nutrient and Water Quality Trends .Michael A. Champ et al. 350 CHAPTER 14: BASIN MANAGEMENT AND FRESHWATER INFLOW 374 Characterization of Freshwater Inflow Modification to Estuaries Resulting from River Basin Development .Marshall E. Jennings 375 Freshwater Flow Rates and Distribution Within the Everglades Marsh Peter C. Rosendahl and Paul W. Rose 385 xxii Effects of Upland Drainage on Estuarine Nursery Areas of Pamlico Sound, North Carolina Preston P. Pate, Jr. and Robert Jones 402 Endangered Estuarine Receiving Waters: The Effects of Low-Flow Land Runoff on Headwaters Biota David L. Correll 419 CHAPTER 15: FRESHWATER INFLOW PLANNING: PART 2 433 Strategies for the Management of Estuaries Rezneat M. Darnell 434 A Dynamic Methodology for Characterizing and Monitoring Estuarine Ecosystems T. L. Linton and S. G. Appan 448 Santee-Cooper Rediversion: Projected Impacts on Fishery Resources and Wildlife Habitats Lee A. Barclay, Jr. and Victor G. Burrell, Jr. 463 Methods of Computation and Ecological Regulation of the Salinity Regime in Estuaries and Shallow Seas in Connection with Water Regulation for Human Requirements Michael Rozengurt and Irwin Haydock 474 FINAL PLENARY SESSION John Clark 507 SUMMARY AND RECOMMENDATIONS OF SYMPOSIUM John Clark and Norman Benson 523 xiv PLENARY SESSION ESTUARIES AND FRESHWATER INFLOW Chaired by Dr. Robert Stewart, Leader, National Coastal Ecosystems Team Slidell, Louisiana INTRODUCTION Robert Stewart U.S. Fish and Wildlife Service National Coastal Ecosystems Team Our purpose here today is to be- gin to grapple with some of the is- sues. These are not new issues. They have been around for some time, but perhaps we can take a fresh look at them. Issues deal with freshwater inflow to estuaries where the quanti- ty and quality of water that flows into estuaries varies considerably. The purpose here in convening this symposium is twofold. First, we need to gain a better understanding of what the issues are; and, second, we need to arrive at some solutions or potential solutions and recommen- dations that will permit us to deal with the issues. There are no guid- ing rules for this symposium other than having a rather lively discus- sion and to reach some agreement on policy issues, technical issues, and on legal issues or new laws by the end of this symposium, so that we can come forward with strong recommenda- tions . WELCOMING ADDRESS Jerry L. Stegman Acting Regional Director Region Two U. S. Fish and Wildlife Service On behalf of the U. S. Fish and Wildlife Service (FWS), it is my pleasure to welcome all of you to the first National Symposium on Fresh- water Inflow to Estuaries. As I looked over the program, I was impressed by the comprehensive subject matter that has been includ- ed. I was also pleased to note the diverse participation by representa- tives of numerous Federal, state, and private agencies. I am sure these ingredients will combine to provide an excellent symposium. You may have asked yourself, how is it that a Fish and Wildlife Ser- vice Regional Office located in Albuquerque, New Mexico, is inter- ested in co-hosting a symposium of this type. The answer is that Texas falls within the Albuquerque Region's jurisdictional boundaries. Some of the most biologically productive coastal waters, barrier islands and salt marshes in the Nation occur along the Texas coast. We are con- cerned with protecting this valuable habitat from man's encroachment. The Fish and Wildlife Service and the State of Texas recognize many major threats to the Texas coastline. Water-development proj- ects are slowly but surely reducing the amount of fresh water reaching the estuaries. Channelization and dredge and fill projects are de- stroying valuable coastal environ- ments. Oil and gas and coal develop- ment are destroying valuable wet lands and are polluting these areas with toxic chemicals. For example, last year's IXTOC-I oil spill dis- charged 3 million barrels which translates into 126 million gallons of oil into the western Gulf of Mexico. Much of this found its way to the Texas coast. There is strong evidence that agricultural pesti- cides are reaching the near coastal areas . All of these and other activi- ties threaten and degrade valuable coastal fish and wildlife habitats and the commercial and recreational values associated with them. Region 2, in cooperation with the State of Texas, has implemented two major thrusts for habitat pres- ervation on the Texas coast. o The first is our active Coastal Land Acquisition Program. For in- stance, since 1977, the FWS has ac- quired approximately 54,000 acres of prime coastal prairie marsh (composed of salt, brackish, and freshwater marshes). These areas provide irre- placeable wintering habitat for wa- terfowl, other migrating birds, resi- dent wildlife, and nursery grounds for finfish and shellfish. o The second is our activities under the Fish and Wildlife Coordi- nation Act, wherein we review and report on various types of Federal water development projects, and re- view permit applications by private groups or individuals seeking Fed- eral permits for various types of private development. For several years now, Region 2 has also identified the problem of reduced freshwater inflow to Texas estuaries as our number one regional environmental problem. We have realized that there is a need for more comprehensive water resource planning in order to preserve fresh- water inflows and to protect valu- able fish and wildlife habitats. Consequently, the Director of the Service gave this region the lead to investigate environmental prob- lems specific to the Texas coast. In 1977 and 1978, we contracted two studies designed to determine, in part, the freshwater needs of fish and wildlife resources in Nueces/ Corpus Christi Bay and in Matagorda Bay, Texas. The objectives of these studies were to develop water man- agement plans and recommendations to assist Federal and state agencies in future development planning, and thus insure the future biological productivity of these bay systems. The study designs and progress have been closely coordinated with state and other Federal agencies. The Nueces-Corpus Christi Study is essentially complete and the Mata- gorda Bay Study is scheduled for completion in late 1981. In 1979, as an outgrowth of these studies, our Region was as- signed the lead role in developing a National Freshwater Inflow Budget Issue Paper in cooperation with the National Coastal Ecosystems Team and the other segments of the FWS. The purpose of this proposal was to con- duct similar studies of all remaining bay systems in the entire United States. However, because of funding restraints, a national, multi-year study was not established at that time. But that pioneering effort set the stage for this week's national symposium. In Texas, we have also identi- fied Galveston Bay as the next bay that needs to be studied for fresh- water inflow needs. The Office of Environment (FWS) is presently pre- paring a budget issue paper on Gal- veston Bay which will describe the serious problems associated with energy development, water resource development, and pollution and their relationships to freshwater inflow needs of that bay system. In summary, the FWS is proud of its past record and efforts on this issue of estuarine freshwater inflow needs. We also pledge our continued effort and support. During your stay at the sympo- sium, if there is anything we can do to assist you, please contact one of our FWS Regional employees. We'll do everything possible to assist you and to make this symposium one of the great milestones in our common goal to preserve the Nation's valuable coastal estuaries for future genera- tions . KEYNOTE ADDRESS: HOW CONGRESS VIEWS ESTUARIES Kieth Ozmore Environmental Consultant to Congressman Robert Eckhardt, Texas First, I want to thank the U.S. Fish and Wildlife Service for the invitation to present the keynote address at this most important sym- posium, and to commend the Coastal Ecosystems Project for sponsoring it. In my estimation, there is no more important area in the Nation than its estuaries, and none which faces greater dangers. My presentation today will deal primarily with two facets of the situation: the view from a congres- sional perspective; and the view of the value of those estuaries, from a member of Congress who represents a District which borders on the Galves- ton Bay System, one of the most pro- ductive estuarine systems in America. I note that my presentation is entitled "How Congress Views Estua- ries." I wish that I could tell you this morning that Congress views the estuaries the same as you and I. But that is simply not the case. It was not so long ago, when the House was considering a bill to gut the Section 404 permit program, that a prominent, influential member of Congress made this statement on the floor: "To hell with fish ... let's look out for people . " What this member failed to rec- ognize is that when we are looking out for shrimp, menhaden, blue crab, speckled trout and redfish, we are, indeed, looking out for people--just the same as we are looking out for people when we pass legislation to help the farmer make his land more productive for protein matter. Most of those attending this symposium already know that our estuaries are extremely productive of protein. Our problem is how to deliver this information to those public officials far inland—Denver , Frankfort, or Des Moines . Several years ago, when Texas A & M University inaugurated its course "Special Topics in Coastal Zone Man- agement," Robert Knecht, at that time Director of the Federal Office of Coastal Zone Management, was one of the guest lecturers. A member of my staff who had recently attended a na- tional oceanic conference along with Mr. Knecht in Seattle, Washington, was driving the agency official to A & M and they got into a conversa- tion on the importance of coastal zone management. My staff member com- mented that this Nation did not need coastal zone management or oceanic conferences in Seattle, Boston and Savannah--it needed such conferences in far-flung inland cities, and Mr. Knecht agreed. In looking over the preliminary program for this symposium, I am quite impressed at the expertise of those making presentations. It is encouraging that this symposium is being held inland—but not too far inland. In fact, hundreds of San Antonio residents commute back and forth to the coast for salt-water fishing and waterfowl hunting. I would like to suggest that additional symposia be held, but that they be scheduled perhaps in state capitals of inland states so that you educate not only members of Congress from those states, but state and local of- ficials as well. I suspect that the vast majority of residents of those areas do not have the faintest idea where shrimp come from or how impor- tant it is to preserve their nursery habitat. Let me hasten to add, however, that all the ignorance of our impor- tant coastal zone is not restricted to inland areas. A number of years ago, the Texas Parks and Wildlife Commission held a public hearing on how much it should charge for removal of bay bottoms. During the course of the hearing, one man who actually lived on the coast questioned why the state should be involved. He asked the question: "What good is that stinking old marsh, anyway?" Dr. Dan Willard, a botany professor at the University of Texas, was sitting up front, and one could almost see the hackles rise on his neck. He re- plied: "I would like for the gentle- man to know that, acre for acre, 'that stinking old marsh' produces more protein than the richest acre of farmland in the Midwest." While many members of Congress may not fully know the value of our coastal wetlands, I suspect that many of our problems lie with the paro- chial positions taken by some mem- bers. We have too few members who take a broad national overview of issues which we deal with every week. Their first, and sometimes only question is: "How does it affect my constituency?" For instance, today much of our energy is being produced from the continental shelf, and even a greater share probably will come from that area in the future. Inland officials read where the Sierra Club or Audubon Society has sued to pro- hibit drilling for oil and gas in an estuary. Their first reaction is that environmentalists are trying to keep constituents from driving their gas-guzzling automobiles and trying to freeze them in the dark just to preserve the habitat of a dickey bird. Which gets me now to the second phase of my presentation. I have long appreciated the beauty of a saltwater marsh and the stillness of an East Texas hardwood bottom. But in recent years I have come to the conclusion that if we are to preserve any of such beauty, we almost have to put a price tag on it. It is too difficult to place a dollar mark on the value that one derives from the aesthetic enjoyment of the outdoors. It should not be that way, but it is. Tellico Dam has shown us that we must have economic justifica- tion for preservation, and in most cases I think we can justify our po- sitions. Certainly we can when it comes to protecting the oceans and their bounties. One of the first concepts to be recognized when we begin to look at the dollar value of any resource is the long-term gain vs. the short- term. The first major battle I be- came involved in was in 1963 when the Texas Parks and Wildlife Commission amended two long-held rules on dredging of commercial oyster shell in Galveston Bay, posing threats to our oyster fishermen. Our argument then, and it still is a valid one, is that we must calculate the value of those reefs on a long-term basis, producing oysters year in and year out, and compare their value on a short-term basis as a component for cement or chemical products. We ar- gued that while their value for the latter may be quite high, if we kept the reefs intact and productive, then they would continue to produce oysters decade after decade, just as they have for thousands of years in the past. Their value, then, on a long-term basis would far surpass their short-term value for building roads or for other purposes. This is no less true for the wetlands which provide nursery grounds for the shrimp, the blue crab, and the finfish. During the past few decades, these areas have been destroyed, bit by bit, a few acres there, and a not so few acres which could have been destroyed had the Wallisville Reservoir project been carried out to completion. As one environmentalist puts it, we have "nickled and dimed our estuaries to death." While I recognize that the subject matter of this symposium is the importance of freshwater inflow, my point is this: if the estuaries are destroyed by dredging and fill- ing, then what good would it do to have the freshwater inflow? During the battle with the shell dredgers, they made the point that Galveston Bay was so polluted and that so much of it was off limits due to high levels of coliform that they might as well be permitted to dredge out the reefs. My positions was that pollution can be cleaned up, and there would be little point in clean- ing up pollution if the entire eco- system had been damaged beyond repair by its physical impairment. My argu- ment has been borne out as a valid one. Today, the biochemical oxygen demand flow into the Houston Ship Channel is only about 70,000 pounds daily, where a decade ago it was ap- proximately 300,000 pounds. So we must not let permanent destruction go unchecked because a temporary sit- uation prevents their use by mankind. The economic value of our wet- lands can be looked at from two view- points: one, its production of com- mercial species of marine life; and second, its production of species which are harvested by the recrea- tional fishermen. First, let me dis- cuss the shrimp fishery, for this is the one that I know most about. Thou- sands of residents along the Texas gulf coast make their livelihood, or part of it, from the shrimp fishery. In 1979, shrimpers landed 41,604,000 pounds of this delicacy at Texas ports, worth $153,115,000 ex-vessel value. By the time this harvest reached the dinner tables of America, it was worth about three times that or approximately $500,000,000. Loui- siana fishermen landed 50,125,000 pounds, with an ex-vessel value of $115,282,000 or $345,000,000 final value. The other three states front- ing on the Gulf of Mexico landed a total of 35,322,000 pounds, ex- vessel value of $109,245,000, or $327,600,000 final retail value. The total landings from the Gulf of Mexico amounted to 127,049,000 pounds, worth $377,642,000 at boat- side, or a whopping $1,133,000,000 dollars final retail value. In the entire nation, only 202,717,000 pounds of shrimp were landed, with an ex-vessel value of $471,573,000. This means, then, that our gulf landings amounted to 62.2 percent of the total American catch and just a little more than 80 percent of the ex-vessel val- ue of the U.S. harvest. Just one little reminder here: all of these shrimp spend some part of their life in the areas that we all are inter- ested in protecting our estuaries. The second economic value we place on our estuaries is their productivity of species important to the recreational fishery. The two most important of those species are the spotted weakfish, known in Texas as the speckled trout, and the channel bass, which we call the red drum or redfish. Speckled trout spawn in the estuaries, while the redfish spawns just offshore, and their fry go up into the nursery grounds of the estuaries. Moreover, two of the principal food fishes upon which these species depend are also estuarine-dependent . I speak of the shrimp and menhaden. Today, there are some 600,000 salt-water anglers in Texas. And with the ever-increasing movement to the ocean-front, this number will continue to increase dramatically. In 1975, the U.S. Fish and Wildlife Service Survey indicated that each saltwater angler fished an average of 12 days annually, spending approxi- mately $11.50 per day while fishing. With the 40 percent increase in costs since that time, this means that each of Texas' 600,000 anglers spent about $16 per day, or a total of $192 per year. All told, the expenditures for salt-water fishing in Texas would total $75,200,000 annually, and this does not include the capital outlay for the sportsman's boat, motor, trailer and terminal tackle. Again, on looking at it from a long-term gain basis, this impact upon the Texas coastal economy not only will continue, but it will continue to grow, as the population grows. Destroy our estuaries, and we destroy this important economic value. I would like to touch for a moment on the subject which you will be discussing here for the next three days--the freshwater inflows into the estuaries. I do not propose to speak as an expert--you will hear from them later. But I do have a few thoughts on the matter. Several years back, when the infamous Texas Water Plan was being proposed, we were told that it would provide a grand total of 2 million acre-feet annually to Texas bays. How generous! I am told that the Galveston Bay system alone needs something like 7 million acre-feet annually to remain productive. Since neither our commercial fisheries nor our sports fisheries are defined as an "industry" they do not legally come in for their share of freshwater flows. But some scheme must be de- vised to assure that enough fresh- water is released from the dams and impoundments to keep our bays pro- ductive. Sometimes I wonder why it would not be feasible to store some of the excessive rainfall during extremely wet years to be released subsequently in extremely dry years, such as we are experiencing now. For instance, in 1972 and 1973 we had something like 72 inches of rainfall in the Trinity River Watershed, where the annual average is about 42 inches. It seemed tragic that this fresh wa- ter inflow perhaps was wasted—al- though we are told that occasional flushings from heavy rainfalls are good for the estuarine systems--but 72 inches? During that period the fresh water reached five miles off- shore. I hardly think that kind of flushing is necessary to keep the estuaries healthy. On the other hand, though, how do you store even a por- tion of that kind of rainfall? One of our commercial fishing friends, a few years after those floods, came up with a proposal to construct a diversionary canal from the Trinity River, around Houston, to dump the surplus into the Brazos. He never did explain where we were to get the billions of dollars with which to purchase the right-of-way for the canal, nor who was going to foot the bill so that the oyster harvest would not be destroyed by the fresh water. Is it feasible to store some of the surplus in wet years? How much would we need to store? How much would it cost? Who would pay the cost? These are some of the ques- tions that need answers. In closing, let me say that we who love our coast are optimists. If we were not optimists, we would have long ago thrown in the towel. But we win a few now and then, such as the significant Wallisville Re- servoir project. I hope that this symposium brings happy results, that we can convince our friends that they too have a stake in our coastal wet- lands ... I hope that you will go away from this symposium with a new dedi- cation, a new hope that is a worthy one--one that will assure a better, fuller life for those coming on be- hind us . Again, thank you very much for the opportunity to be a part of this important symposium. OVERVIEW OF U.S. WATER RESOURCES PLANNING, POLICIES, AND LAWS THAT AFFECT COASTAL AREAS Gerald D. Seinwell Acting Director, U.S. Water Resources Council Washington, D. C. Estuaries play a subtle yet vi- tal role in our existence. They are the source of many of life's ameni- ties for all of us on land. And, freshwater inflows play a subtle yet vital role in the existence of the estuary. The delicate balance of fresh water and salt water breeds both the bounty of the estuary and the potential for its destruction. The environment which is formed where a river flows to the sea attracts not only spawning fish, aquatic mammals and shellfish, but also people. More than half of our Nation's population lives within 50 miles of the coast. Most of that population is concentrated in cities which thrive on or near the mouth of a river--Boston on the Charles, New York on the Hudson, New Orleans on the Mississippi, San Francisco on the Sacramento-San Joaquin. These con- centrations of people place great de- mands on the coastal zone. As a re- sult, our industrial, agricultural, commercial, and recreational needs are threatening the health and pro- ductivity of our estuaries. My purpose in coming here today is not to alert you to the problems surfacing in the coastal zone. Your presence indicates your awareness of these problems. Rather, I am here to lay before you the unbeaten path of U.S. law and policy which, if properly implemented, might lead us toward the goal we recognize today --the proper respect for our estua- ries and their lifeblood: the fresh- water inflows. I call the path unbeaten be- cause, although the laws exist and the policy has been enunciated, we have yet to take our first forceful step toward consideration of fresh- water inflows and their recipient estuaries. The first piece of legis- lation to come to mind when mention is made of the coastal zone is, of course, the Coastal Zone Management Act of 1972. Passage of that Act marked congressional recognition of the coastal zone as one of our Na- tion's prized resources. For manage- ment and protection of this resource, Congress naturally looked to the states — the source of local govern- ment zoning power. Since locali- ties derive their power to zone from a state enabling act, the state re- serves the right to require that each locality respect the needs of the en- tire state in its individual master plan. This supervisory function is what Congress sought to fund with the Coastal Zone Management Act. Federal funds assist the states in the devel- opment and administration of manage- ment programs designed to ensure that the locality respects the interests of the state and that, in turn, the state respects the interests of the 10 nation. This framework seems tailor- made to handle our freshwater inflow concerns. However, National objec- tives have not been the focus of the plans to date. Under the CZM program, each participating state must identify the boundaries of its coastal zone, define permissible land and water uses which have a direct and signi- ficant impact on the coastal zone, designate areas of particular con- cern, identify means of state con- trol over land and water uses (in- cluding constitutional provisions, statutes, regulations, and judicial decisions), and determine the re- spective responsibilities of local, state, regional, and interstate agencies . If participation were any measure of success, there would be cause to rejoice because 31 of the 35 states which are eligible to participate in the CZM program are doing just that. However, compli- ance with the procedural require- ments of the Act does not neces- sarily ensure that substantial a- chievement of national coastal zone management goals will be realized. The Water Policy Task Force on Environmental Statutes noted in its 1979 report that there is lin- gering doubt about the efficacy of the CZM program. In responce to such criticism, the Office of Coast- al Zone Management has offered a- mendments of its enabling legisla- tion which would serve to clarify the national objectives for the coastal zones and OCZM's authority to condition Federal assistance on the pursuit of those objectives. The President recommended enactment of these amendments in his 1979 En- vironmental Message. If these amend- ments were adopted by the Congress, the present patchwork of coastal zone programs may have a chance to become the tightly-knit fabric envisioned by the Congress when it passed the Coastal Zone Management Act in 1972. Another major piece of legis- lation which could provide a means for considering freshwater inflows to estuaries is the ubiquitous National Environmental Policy Act (NEPA) of 1969. Certainly the environmental impact statement (EIS) which NEPA requires can and should reflect a proposed project's probable impact on the timing, quality, and quantity of freshwater inflows to estuaries. One of the major impediments to consideration of these impacts in EISs to date has been a lack of awareness of the freshwater inflow problem. President Carter has al- ready resolved two identity crises which are similar to those suffered by the freshwater inflow and its re- cipient estuary. In Executive Orders 11988 and 11990, issued in 1977 under NEPA, the National Flood Insurance Act and the Flood Disaster Protection Act, floodplains and wetlands gained national recognition. Their protec- tors are now perceived as a force to be reckoned with. The WRC, CEQ, and FEMA were assigned the responsibility of assisting the other Federal agen- cies in their implementation of the orders and in monitoring their effec- tiveness. Perhaps if estuaries were similarly honored as the subject of an executive order, freshwater inflow would in turn get its fair share of attention. Of course, the potential may be argued that the existing execu- tive orders are sufficient to en- compass protection of estuaries and their freshwater inflows. Afterall, estuaries are a part of the flood- plain and inflows do flow in through wetlands. Estuaries are a very special part of the floodplain and 11 special attention must be paid to them. But, the President's articu- lation of this point in an order to the executive agencies could very well provide the impetus needed to get the inflow problem considered in environmental impact statements issued under NEPA and in other agency decisionmaking . There remains one further piece of legislation which predates all that I have discussed this far. In 1968, Congress passed what has since been dubbed the Estuary Protection Act. Unfortunately, this is not the name that Congress gave to the act. In fact, Congress did not name the act at all. Ordinarily, that dif- ference would be inconsequential. After all, NEPA has proven to be a potent statute, even though many still call it the National Environ- mental Protection Act rather than the National Environmental Policy Act. But, in the case of the Estu- ary Protection Act, the misnomer signifies all that is missing from current U.S. performance on estu- aries. The act purposes to "provide a means of considering the need to protect, conserve, and restore es- tuaries." The act provides for consideration, not protection. In 1970, a study was made pursuant to this act. No protection has ensued. There is a section of the act which has the potential to force Federal agencies to give special considera- tion to the needs of estuaries. This section provides that "in plan- ning for the use of development of water and land resources all Fed- eral agencies shall give considera- tion to estuaries and their natural resources, and their importance for commerical and industrial develop- ments, and all projects and reports affecting such estuaries and re- sources submitted to the Congress shall contain a discussion by the Secretary of the Interior of such estuaries and such resources and the effects of the project on them and his recommendations thereon." Note the delegation of responsibility to the Secretary of the Interior. The Congress in 1968 clearly gave the Secretary of the Interior the responsibility for administer- ing the act. Since that time, Pres- ident Nixon transferred responsibili- ty for commerical fisheries from In- terior to Commerce, thereby creating the problem of who should administer the Estuary Act. President Nixon is- sued that reorganization order in 1970. Since then, no action has been taken under the 1968 act. This conflict between Interior and Commerce over responsibility for the Estuary Act embodies all of the conflicts which plague our coastal areas. The coastal zone is a combat zone. Spawning grounds are fast be- coming sparring grounds. The men- haden and the mollusk pitch their freshwater demands against those of the power plant, the refinery, the irrigation canal, and the reservior. It doesn't take much to figure out who's winning the battle. If you need help--recall the snail darter and the Tellico Dam. Consider the interests of En- ergy, Transportation, Commerce, and Agriculture--all represented at the Cabinet level. Then it becomes clear that the problems which beset the estuary are the problems which beset the Estuary Protection Act. The bat- tle which rages in the coastal zone, rages as well on Capitol Hill. Trans- portation wants upwater ports. En- ergy wants hydroelectric power plants. Agriculture wants upstream diversion. Commerce wants coastal 12 development. If there has been lit- tle consideration of estuarine needs amid all this construction, it is not for lack of law on the books. It is for lack of coordination. These com- peting agencies must be brought under a unified plan if development is to be balanced with preservation. But, no one yet has been appointed to do the balancing. So, development goes on upstream without regard to down- stream, and now without regard to latter. This call for national coor- dination and farsightedness harks back to the provisions of the Coast- al Zone Management Act. CZMA could provide the necessary focus. How- ever, CZMA is limited in its effec- tiveness for a number of reasons. First, the program is voluntary. Second, the requirements are pro- cedural not substantive. The com- bination of these two factors tends to encourage states to take the money and run. Many of the participating states have succeeded in designating only one "area of particular con- cern." This kind of compliance is the means to no end. States must be encouraged to view the national interest. Some may do so simply by looking to a neigh- boring state. One of the most press- ing needs in the administration of CZMA is for improved coordination be- tween or among two or more states which share a common watershed. Sec- tion 309 of CZMA added in 1976, amendments which provide for inter- state grants to coordinate state coastal zone planning with respect to contiguous area--but it has never been funded. The problem of fresh- water inflow cannot even be approach- ed until there is provision for in- terstate planning. Fortunately, a few states are beginning to request that Section 306 administrative grants be made available for inter- state planning. For example, Pacific Northwest states, through the medium of the Title II river basin commis- sion, have requested interstate funds for the benefit of the Columbia River Estuary. The Great Lakes and New England River Basins Commissions have also been the recipients of Section 306 funding. In reviewing the obstacles which OCZM faces in carrying out its man- date, I have mentioned the lack of coordination among states and the lack of coordination among Federal agencies. There remains a third obstacle which also should be obvious --the lack of coordination between the states and Federal agencies. Section 307 of the act is entitled, "Interagency Coordination and Coop- eration." This section requires that Commerce coordinate its activities with other Federal agency activity. It also requires that each Federal agency operating within a state coastal zone be consistent to the maximum extent practicable with that state's coastal zone management pro- gram. As of this moment, these words have a hollow ring. Because there is little coordination of agency activi- ty at the Federal level, it would seem to follow that there can be lit- tle or no coordination of that activ- ity at the state level. These polit- ical realities make it difficult for OCZM to keep the goal of protection and wise use of the estuary at the forefront of its management program. In addition, the provisions of the Coastal Zone Management Act, as they are now interpreted, cannot ade- quately treat the freshwater inflow problem. For instance, Section 315 of the act makes grant money avail- able for the acquistion of estuarine sanctuaries. Florida is one state which has taken advantage of this 13 provision to create an estuarine sanctuary at the mouth of the Apala- chicola in the Gulf of Mexico. But this sanctuary protection does not extend upward into Alabama and Georgia to reach the freshwater trib- utaries which feed the river and the estuary. The sanctuary designation cannot or at least does not ensure proper quality, quantity, and timing of the freshwater inflow which origi- nates beyond the sanctuary's reach. The states of Florida, Georgia, and Alabama have agreed to pursue a Level B study to evaluate the water resources in the Apalachicola-Chata- hoochee-Flint River Basin. In their FY 1982 study proposal to the Water Resources Council, the three states recognized that "all the uses and all the parts of the river system are in- terrelated." The states and the council believe that a Level B study can enhance the existing uses and values of the river system, while at the same time reducing the present conflicts over river system manage- ment . Another factor which makes the act unresponsive to the freshwater inflow problem is one which could be corrected by a change in the ad- ministrative interpretation of a few choice words. The act provides that land and water uses governed by state coastal zone plans be only those which "have a direct and significant impact on the coastal waters." I think all of us here today would agree that freshwater inflow has a direct and significant impact on our coastal waters. Unfortunately, most of the states do not see it quite that way. In their evaluations of a sited project, they too often tend to look no further than the site itself. States must be encouraged to see be- yound the site, beyound even state borders. But, if they are to do so, they need the impetus the Federal Government can provide; that means the money, and the authority to make interstate agreements. That means the Coastal Zone Management Act, as it may be amended this fall. Up to this point, I have painted a rather gloomy picture. This was done in the spirit of realism. I would like to have been able to come before you and assure that freshwater inflow has been duly considered in every federally assisted development plan or project. It has not. There are several actions the council could take to assure that estuaries and their freshwater needs are more adequately considered. First, the council could examine the adequacy of existing and proposed policies and programs and recommend to the President changes in Federal programs and policies which might be needed. We have this authority under the Water Resources Planning Act. Second, the council could also take more concrete steps to encourage the states, which are funded by our Title III grants, to regard estuarine needs in their water resources planning. The Title II river basin commissions, which are funded partly by the coun- cil, have already begun to move toward proper consideration of fresh- water inflow and we can further en- courage this. These commissions are the ideal body to deal with the problems of interstate coordination in water resources plans. They have been created at the request of the states because those states recognize the inferiority of a development plan which does not look across state lines. As I mentioned earlier, three of these commissions have succeeded in getting CZMA funding in addition to our Title II funds. This is one 14 example of successful coordination among Federal agencies whose object- ives and responsbilities overlap. The Council could give increased attention to freshwater inflow in its assessment activities, in its policy analysis, in its state grant program, and in its regional planning program. The council can also ensure that freshwater inflow will be adequately treated by the planners of Federal projects. Section 103 of the Water Resources Planning Act requires the council to establish principles, standards, and procedures for the formulation and evaluation of Federal water projects. At tomorrow's coun- cil meeting, the members will--I hope--approve the publication of the revised P&S as a final rule. The new P&S included the requirement to con- sider instream flows. The procedures are contained in our manuals: for National Economic Development, for Environmental Qual- ity, for Regional Economic Develop- ment, and for what has been termed Other Social Effects. The Environ- mental Quality manual, for instance, provides that planners comply with relevant provisions of the Coastal Zone Management Act. This necessari- ly broad mandate will not of itself ensure due consideration of freshwa- ter inflow to estuaries. The manual cannot possibly set out all the ele- ments of each of the thirty or so Federal laws for which it seeks com- pliance. However, the council plans to mention the peculiar freshwater inflow problem in its Reference Hand- book which accompanies the various manuals going to the planners in the field. Luckily, the state-of-the-art is such that estuarine scientists can now predict the effects that irriga- tion projects, energy facilities, and harbor dredging will have on the del- icate balance of the estuarine eco- system. Scientists can now suggest thresholds for estuaries. These ad- vances in technology will be reflect- ed in the planning done in accordance with the Council's Principles and Standards . Thus far, I have recounted how each of the council programs might respond to the newly perceived needs of the estuary. There is one further council program which had the poten- tial to become a driving force in estuary protection. I am speaking of the Independent Project Review. In January 1979, President Carter signed an executive order which directs that the council perform an impartial technical review of preauthorization reports and preconstruction plans for Federal and federally-assisted water and related land resources projects. The Independent Project Review serves as a quality control mechanism. The order requires that all agencies sub- mit cost-benefit information; evalua- tion of reasonable alternatives; evidence of compliance with environ- mental and other laws; and evidence of public, state, and local involve- ment in the planning process. A detailed finding of the areas of compliance or noncompliance will be returned to the agency head at the end of the 60-day review period. This information will also be trans- mitted to Office of Management and Budget (0MB) and to the Congress when the agency submits its project proposal to the Congress. It is im- portant to note that the independent review is strictly a staff technical review. The findings do not go to the council members for review or approval but are transmitted by the chairman to the planning agency and are available to the public. The independent project review will provide a checkpoint for see- ing that the estuary and its fresh- water inflow received proper consid- 15 eration in the planning of Federal water resource projects. To date, the project review unit is still engulfed in the con- tinuing battle between the White House and certain factions of Con- gress over water policy in general and particularly over the omnibus water projects bill. Although we have statutory authority to per- form the review, a rider on our 1980 appropriations bill prohibit- ed the use of FY 1980 funds for the review until it was authorized after the date of the appropriations bill. The Senate Environment and Public Works Committee has reported out a bill authorizing the review but the House has not. We antici- pate some action on this matter this month, but the situation right now is so uncertain that any pre- diction of future congressional ac- tion would be meaningless. Suffice it to say that the council believes the independent review is necessary to ensure that projects are well planned; we are confident we will get the review up and running; and we would welcome the opportunities that the independent project review would provide for the consideration of estuaries and freshwater needs. So much for what the council may do with existing programs. I perceive that there could be a further role for the council in this arena. All of the interests which are finding themselves in pitched battle with one another in the coastal zone just happen to be mem- bers of the Water Resources Council. Actually, this is no coincidence. One purpose of Congress in creating the council was to coordinate all those agencies whose activities have some bearing on water and related land resources. The council can serve to mediate among the competing interests of Energy, Defense, Trans- portation, Agriculture, Housing and Urban Development, and the Environ- mental Protection Agency, but we can only do it successfully if those agencies want our help. For example, the council could offer the impetus needed to get the Estuary Protection Act to live up to its name. The Act needs recognition, funding, and the resolution of who is responsible for what between Interior and Commerce. The council could, in the next fiscal year, do the necessary analysis to determine how the act could be imple- mented in concert with agency reviews done under Section 404 of the Clean Water Act, NEPA, and other statutes to avoid duplication. This is the role that Congress envisioned for the council when it first conceived the idea of a coordinating, mediating body. To what better use could council efforts be put? Of course, with its small staff and other cur- rent initiatives, the council will need the support of its members to devote its resources to the fresh- water inflow/estuary problem. I have tried to set forth for you today the pattern of law and policy which surrounds agency de- cisionmaking at the Federal level. I have indicated the problems we have encountered in implementing that law and policy. I will now sum up some solutions to these probems which could be implemented at the national level . The Nation must be made aware of the valuable resource that is the estuary. The Nation must also be made aware of the critical role that freshwater inflow plays in the mainte- nance of this valuable resource. One way to achieve this would be a direc- tive such as an executive order from the executive office, similar to those employed to alert the country 16 to the special needs of wetlands and f loodplains . The Estuary Protection Act could be seriously implemented. Undoubtly, OMB and the Congress would be more inclined to grant the necessary fund- ing if the responsibilities of the various departments under the act be- came more clearly delinated. The Coastal Zone Management Act could be strengthened. Because the program is voluntary, the states should have more incentive to parti- cipate. Mitigation funds under the Coastal Energy Impact Program are a part of that incentive. These funds for the mitigation of effects caused by the siting of energy facilities are only available to those states which develop a coastal zone manage- ment plan. Care must be taken that this funding is not abused, but that it remains available to cooperating states . Regional or interstate planning must be encouraged. Within that scheme, some thought should be given to the funding of those states which are currently ineligible for CZM funds. The CZM Act must acknowledge in its eligiblity determinations that a state which has no coastal zone of its own may still be a major factor in the preservation of the estuarine system. Without the inclusion of these states, the act cannot pretend to consider the freshwater inflow needs of the coastal zone, and thus it cannot pretend to comprehensively consider the health and productivity of the estuary. All of this, of course, is more easily said than done. But as we are often told, recognition of a problem is the better half of solving it. I would like to see the Water Resources Council become part of the solution. And, that will take your help. The council provides a ready forum for discussion and solution of interagency coordination problems and of policy differences. I have the authority to propose the agenda for council action, and I have a small but competent staff to back- ground the issues and propose the options. But, unless the members are disposed to act, unless they sense in their agencies some interest in a problem and some willingness to yield some portion of agency turf, very little will happen. The council members are, in many cases, the secretaries of your departments. If you push, and we pull, our estuaries will be the winners . 17 ROLE OF THE NATIONAL MARINE FISHERIES SERVICE IN THE PROTECTION OF FRESHWATER INFLOW ESTUARIES John W. Rote Director, Office of Habitat Protection National Marine Fisheries Service Washington, D.C. Presented by Kenneth Roberts Deputy Director, Office of Habitat Protection National Marine Fisheries Service Under the Fishery Conservation and Management Act of 1972 and other laws the National Marine Fisheries Service (NMFS) is assigned the man- agement and conservation of the Na- tion's living marine resources, in- cluding those of a coastal, estu- arine, anadromous , and offshore na- ture. NMFS regards preservation and enhancement of the productivity of these resources and the habitats upon which they depend to be an es- sential aspect of this responsibi- lity. The goal of this symposium is to review problems associated with freshwater inflow to estuaries and to formulate recommendations. Un- der this goal the purpose of my presentation is to emphasize the critical importance of freshwater inflows to marine commercial and rec- reational fisheries and to discuss some of the problems and experiences we have encountered in the protec- tion of inflows. Mineral and organic nutrients from freshwater inflows contribute to the particular richness of estu- arine productivity. Inflow velocity, in combination with tidal forces, in- fluences estuarine circulation, the recycling of nutrients, and, in some cases, the distribution of organisms. The net result of these and other factors is a national system of rich, and productive estuaries, which are important because of their unique aesthetic qualities and the valuable living marine resources which they support. The importance of the estuarine environment to fisheries of the Uni- ted States is considerable. Sixteen wetland species or species groups account for 57 to 63 percent or about three billion pounds of recent annual U.S. commercial fish landings. It is estimated that 60 to 70 percent of the most valuable commercial species of the Atlantic and gulf coast occupy estuaries during all or part of their life cycles. Data compiled by the NMFS Rec- reational Fisheries Program indicate that in 1970 about 1.6 billion pounds of fish were caught by marine rec- reational fisherman. A 1975 study indicated that retail sales of about 2 billion dollars were attributable 18 to marine recreational fishing. Since the majority of marine angling is for finfish, the importance of estuarine- dependent and related species to rec- reational fishing is apparent. The basis for NMFS's resource protection activities stems princi- pally from the Fish and Wildlife Coordination Act (FWCA) and the Na- tional Environmental Policy Act (NEPA) . Protection responsibilities also derive from the Fishery Conser- vation and Management Act (FCMA) , the Coastal Zone Management Act (CZMA) , the Endangered Species Act, the Marine Mammal Protection Act, and the Columbia River Basin Fishery Develop- ment Program Act (Mitchell Act) . Due to the need to focus our ex- isting program resources on problems of the highest priority, we are at this time beginning to place more emphasis on developmental impacts, which are related to or dependent on freshwater inflows. The San Francis- co Bay and Delta, Columbia River, Chesapeake Bay, and the Gulf of Mex- ico coastal region have been identi- fied as particularly important areas of concern. I am going to briefly address each of these four areas. The urban-suburban area sur- rounding California's San Francisco Bay and Delta supports about 5 mil- lion people. With its strategic lo- cation and its huge natural harbor, the bay is a major center for com- merce and industry. The estuarine system itself has historically pro- vided abundant quantities of fish and shellfish. Of all our Nation's major estuaries which have had their fresh- water inflows altered, San Francisco Bay and the Sacramento-San Joaquin Delta stand out among the others. With population growth has come major changes to the estuarine sys- tem. Since the arrival of the gold seekers in the mid-19th century, intertidal wetlands have been re- duced to about 17 percent of their former size. The result has been the loss of fish and wildlife habi- tats and a reduction of tidal-relat- ed flushing, which in turn has led to progressive deterioration of the quality of bay waters. In particu- lar, increased trans-basin diversion of river inflow has limited the abil- ity of the system to flush itself naturally. Currently, with inflows of only 5,000 cubic feet per second (cfs) from the Sacramento-San Joa- quin Delta, one out of eight gallons of "freshwater" entering the bay is now sewage effluent. The State of California esti- mates that the State's chinook sal- mon populations have been reduced 90 percent from their historic lev- els. Since the early 1960s spawn- ing salmon in the Sacramento River system have declined more than 50 percent from the 1959-63 annual average of 420,000 fish. Striped bass populations in the San Francis- co Bay estuary have also declined by between 60 percent to 80 percent. A major factor responsible for these reductions has been reduction in freshwater inflow to the estuary. Two major diversions from the delta (the Central Valley Project and State Water Project pumping facili- ties) are used to export water to the south. The physical loss of fish caused by these diversions is sub- stantial. Evidence collected by the California Department of Fish and Game indicates that the loss of young striped bass to diversions is a major factor threatening survival of this species in the estuary. It has been estimated that 31 percent of the striped bass and 25 percent of the young chinook salmon are passed 19 through these pumping facilities and lost from the estuary. The ac- tual diversion of striped bass is believed to be even greater because essentially all of the striped bass eggs and larvae approaching the pumps are passed through the diver- sion system into canals. Continued or increased diver- sion of fish, fish eggs and fish larvae from the estuary will likely reduce the population's capability to be self-sustaining. If the ex- port of fish from the system is al- lowed to continue, the once-impor- tant fisheries of San Francisco Bay and tributaries may be even more seriously impaired. The inflow to the Columbia Riv- er estuary has also been altered. The most obvious impact to the fisheries, aside from the recent eruption of Mt . St. Helens, has occurred from habitat losses in upstream areas due to dams and reservoirs. Under the Mitchell Act, the NMFS has a long standing commitment to restoration and en- hancement of Columbia River salmon and steelhead trout. These popula- tions have been greatly impacted by mainstream hydroelectric development. As many of you know, up-river salm- on stocks, which have been declin- ing for many years, are now precar- iously few in number. Even with intensive management, Columbia River salmon and steelhead trout have also been substantially reduced from his- toric levels of abundance. As a re- sult, careful study is now being given to various aspects of this problem, including freshwater inflow requirements in the river and estu- ary, in order to better manage the survival of young salmon during their downstream migration. In Chesapeake Bay, as well as other east coast estuaries, stocks of striped bass have declined so drama- tically that Congress has approved and authorized funding of special studies to determine the cause. Ban- ning the commercial harvest of shad is being considered in Chesapeake Bay, since the catch has declined more than 80 percent since 1970 (i.e. from 5,150,000 to 994,000 pounds). On an "average day" about 1 gal- lon out of every 30 gallons of fresh- water inflow to the bay comes from sewage effluent. During the 1980 's one of every two to three gallons of Chesapeake bay inflow will be warmed by electrical generators. Each time a bay area home is developed, approx- imately four tons of silt are added to the Chesapeake. Yet it is esti- mated that the land needed for resi- dential purposes will approximately double between 1970 and 2020. Pro- jected increases in manufacturing indicate that industry also will require 50 percent more land. As populations and industries increase, more and more fresh water will be impounded and diverted to satisfy municipal and industrial needs. Unless political, social, and economic values are changed, the valuable natural resources of Chesa- peake Bay may very well continue to dwindle and go the way of the Atlan- tic and short-nosed sturgeon. The Gulf of Mexico estuarine area with its 207 estuaries is the largest in the United States, except- ing those of Alaska. Through the early 20th Century, its fisheries did not assume major national importance. However, since 1940 things have changed. The gulf's predominantly estuarine-dependent fisheries now produce nearly 70 percent of all United States commercial fish and shellfish and over 30 percent of the dollar value. Yet development and agriculture are altering the vital comingling of fresh and salt water in Gulf estuaries. 20 The large estuaries of the Florida Everglades were once fed by millions of gallons of fresh water from the Kissimmee River-Lake Okee- chobee and Big Cypress drainages. Over the last 80 to 90 years more than 1,500 miles of canals have been constructed to drain, divert, reroute and store this freshwater in "con- servation areas". This has been done to replenish groundwater withdrawal by Miami and the populous Gold Coast. Freshwater depletion has intensified because of the prolonged lack of significant rainfall from hurricanes over the past decade. The result of this depletion has been a lowering of overall Everglades water levels by nearly six feet. Accompanying this has been a drastic reduction in characteristic marsh and man- grove communities, and disappear- ance of native soil due to oxida- tion and fire. Fisheries in the Ten Thousand Island area of Florida Bay are clearly experiencing decline. Hypersalinity is now common near- shore and once-abundant commercial and sport fisheries for redfish and sea trout have undergone substan- tial declines. additional freshwater diversion this problem could become a major afflic- tion. In the north-central gulf area, water-dependent agriculture poses a unique and substantial threat to thousands of acres of low-salinity marsh habitat. Rice growers in Ver- milion Parish, Louisiana, concerned that saline water from Vermilion Bay will enter their fields, have proposed a series of permanent barriers to saline inflow. However, these bar- riers would cut off tidal exchange and segregate between 3,000 and 9,000 acres of low salinity marsh from the Vermilion Bay estuary. This impor- tant nursery habitat and area of productivity would be lost. Also lost would be millions of pounds of commercially and recreationally im- portant white shrimp, blue crabs, menhaden and other estuarine-depen- dent fish and shellfish. Thousands of tons of plant detritus and dis- solved organic matter, upon which Louisiana's estuarine food webs are based, would be lost from the estua- rine system. Apalachicola Bay in the north- east Gulf of Mexico is remarkably free of pollution and supports thriv- ing oyster, shrimp, and crab fish- eries. Proposals to dam the Apala- chicola River at several locations have been staunchly opposed because of the potential degradation of and alteration to freshwater inflows. However, farms and rapidly growing cities annually pump hundreds of millions of gallons of water from the headwaters of the river. This water use may result in much more damaging long-term impacts to the estuary than would the proposed water projects. Oyster beds are now being lost from intrusion of oyster predators and parasites upstream in the bay. With To wrap up, the maintenance of our Nation's estuaries is of vi- tal concern because of their impor- tance to living marine resources productivity, and maintenance re- quires inflows of suitable quality and quantity. Because of the NMFS responsibility for managing living marine resources, our impact assess- ment divisions and research elements have much to gain from these proceed- ings. We need additional research into freshwater inflow alterations and their impacts on the estuarine environment. We also need much more of the kind of information exchange which is occurring at this symposium. Finally, we need to assure that our information is adequately applied in 21 the regulatory and development deci- these needs can we adequately add- sions which impact on freshwater in- ress the problems which have brought flows. Only through confronting us together today. 22 FRESHWATER INFLOWS AND FISH AND WILDLIFE SERVICE OPERATIONS Michael Spear Associate Director-Environment U. S. Fish and Wildlife Service Washington, D.C. The mission of the U.S. Fish and Wildlife Service (FWS) is to provide the Federal leadership to conserve, protect, and enhance fish and wildlife resources and their habitats for the benefit of people. Our authorities are derived from direct congressional mandates, such as the Fish and Wildlife Coordina- tion Act, National Environmental Policy Act, the Endangered Species Act, as well as from executive and secretarial orders. I will comment on the major responsibilities of the FWS in the coastal zone and why we are concerned about freshwater inflow and the preservation of fish and wildlife habitats in estuaries. The Service has responsibilities in zone: several major the coastal that are directly involved in estuarine activities. Within the Division of Eco- logical Services, we have ex- perts in marine biology and fisheries biology who evalu- ate works or activities that propose modification of estu- arine systems, wetlands, and shorelands. As an integral part of their evaluation, they include all means and measures necessary to preserve the in- tegrity of the ecosystem. We have direct regulatory re- sponsibilities in administering the Endangered Species Act. There are over 40 federally- designated endangered species of birds, reptiles, mammals and fish in the coastal zone. Under the Fish and Wildlife Coordination Act (FWCA) we are charged to evaluate the effects of all federally funded, li- censed or permitted develop- ment projects on fish and wildlife resources and provide comments to the permitting or funding agencies. We review plans, recommend modifications or plans, and recommend miti- gation measures when appro- priate. We implement the provisions of the FWCA primarily through the Division of Ecological Servi- ces (ES). There are 25 ES Field Offices and Sub-Offices located on or near coastal areas The FWS has 115 national wild- life refuges on the coast that include over seven million acres . We participate in the Migra- tory Bird Treaty with Mexico and Canada which charges us with protection and management of all migratory birds includ- ing waterfowl. We have an active program to assist our Nation in planning and locating energy develop- ments in the coastal zone. This work includes developing methods for assessing and predicting impacts, assembling information for use in impact 23 assessment and project plan- ning, and conducting an eco- logical inventory of coastal resources . We administer part of the Anad- romous Fish Development Program and the Federal Aid to Fish and Wildlife Restoration Programs that provide funding for state conservation agencies. Many of these projects are in coastal areas . We review and comment on coast- al zone management plans devel- oped by states under the Coastal Zone Management Act. With stable budgets and person- nel limitations to accomplish the work in these inflationary times, the FWS recently went through an evalua- tion to identify resource priorities. The FWS concern for the coastal zone of the United States came out clear- ly. As a result of this effort, we are shifting people and funds to ad- dress these problem areas. Of the 70 nationally Important Resource Problems in 1980, the highest five involved estuarine ecosystems and more than half involved coastal areas. These will be updated peri- odically to address new problems as they arise. The most productive areas in the coastal zone for fish and wild- life are estuaries which depend upon freshwater inflow for their existence. We are deeply concerned when development projects on rivers reduce the volume of freshwater in- flow, alter seasonal inflows, or change sediment or nutrient con- tent. We are concerned when navi- gation and flood control projects prevent the natural distribution of fresh water and sediment into estuarine systems. The dumping of contaminants and sewage into estu- aries through river pollution or through industrial and urban devel- opments and non-point pollution from agriculture located directly on estuaries has magnified the de- terioration of estuarine habitats. The fact that our most produc- tive coastal fish and wildlife hab- itats--estuaries--also attract people and industry intensifies our problem of protecting and preserving them. Many of our largest metropolitan areas--Boston, New York, Baltimore, Washington D.C., New Orleans, Hous- ton, San Francisco, and Seattle-- were located on estuaries because of their natural harbors and because they are attractive places to live near and develop. I will concentrate my remarks on examples of some estuarine areas where critical freshwater inflow quality or quantity problems have developed. I will begin with the New York area and will discuss prob- lems geographically around our coast to San Francisco Bay. The Raritan Bay in the lower Hudson River estuary system is lo- cated in the New York metropolitan area. This system receives polluted freshwater inflow from the Raritan, Passaic and Hudson Rivers. This em- bayment is considered the most heav- ily polluted estuary in the North- eastern United States, and its prob- lems were recognized over a cen- tury ago. By 1880, commercial har- vesting of oysters and clams was pro- hibited because the shellfish were contaminated. This immense problem must be solved by reducing nutrient inputs, industrial wastes, and domes- tic sewage. Marsh restoration must also be emphasized. If Raritan Bay is ever to produce the food and 24 recreation of the past, a massive cleanup program will be necessary. Even if influxes of pollutants were reduced, the residual levels of con- tamination in the sediments might be sufficient to affect the estuarine biota for several decades. Action programs to clean up these rivers have been resisted because of their costs. Although estuarine systems are capable of treating some organic wastes, they are not capable of hand- ling unlimited volumes as the Raritan Bay case exhibits. Chesapeake Bay is the largest estuary on the east coast and is sur- rounded by a population of about 8 million people. The principal stresses on the system are sedimen- tation, nutrient enrichment and in- flux of toxic substances. There have been widespread changes in the bay biota in recent years and the most critical are the loss of rooted aquatic vegetation and the decline in oyster production. Dredging of navi- gation channels, construction of harbor facilities, erosion of the shoreline and the watershed, accumu- lation of toxic materials and heavy metals in the sediments and biota have been primary problems. The Environmental Protection Agency, U.S. Army Corps of Engineers, Fish and Wildlife Service, universi- ties, states, and other groups are conducting studies on Chesapeake Bay and there is strong support for pru- dent baywide management decisions. The FWS is working actively to pre- vent further deterioration of this valuable ecosystem. The State of Florida has serious freshwater inflow problems in Florida Bay and along the southwest coast. These problems began in 1882 when a small canal was constructed which diverted the southerly flowing water of the Kissimmee-Okeechobee-Ever- glades system into the Caloosahatchee River and then into the Gulf of Mexi- co. Substantial canal and water di- version efforts by private groups, the State of Florida, and the Federal Government have continued to redirect water that historically flowed south- ward through the Everglades into the south Florida estuaries. Most of the diversion has been for flood control, urban development and agriculture. The reduction of water flow through the Everglades and Big Cypress drain- ages into the estuaries has had the following consequences: The area of the south Florida Everglades has been reduced by 50 percent. Water levels in the Everglades have been reduced by 5 feet. The average period of overland flow in Everglades National Park has been reduced from 8 months to 4 months . Wading bird populations in freshwater wetlands have de- creased from about 1.5 million in 1935 to 300,000 today. There has been a catastrophic reduction in nursery habitat for estuarine finfish and shell- fish. Discharges of fresh water from canals into estuaries are often confined to short time periods and the sudden surges result in fish and shellfish mortalities in estuaries. Florida Bay has developed into a hypersaline area. It has es- sentially ceased to function as an estuary. 25 Solutions to these problems in- volve restoration of the natural sheet flow drainage and water storage capacity of the Everglades and Big Cypress systems. Without an appro- priate timing and allocation of fresh water to the estuarine and coastal systems of Florida, the abundant resources which attracted many people to that State initially will be gone. This will not only affect Florida's coastal waters but the Gulf of Mexico fisheries as well. Part of Apalachicola Bay has been established as a National Estu- arine Sanctuary. Extensive studies in Apalachicola Bay and the Apalachi- cola River have identified the close relations among river watershed man- agement, river inflow and estuarine production and species composition. The FWS is working with the State, local authorities, and other Federal agencies to prevent the estuarine degradation that has occurred in south Florida. The Louisiana coastal region comprises the most productive estu- arine system in the United States because of the large inflow from the Mississippi River and the vast wet- land acreages it has created. Louisiana estuaries support about 20 percent of the wintering population of dabbling ducks in the continental U.S. and about 30 percent of the continental wintering population of diving ducks. Louisiana leads all states in the weight of commercial fishery landings and supported over 5 million days of sport fishing in 1975. The region has 148 colonies of nesting seabirds, shorebirds and wading birds. In 1976, these colonies included over 750,000 birds. These fish and wildlife resources de- pend upon wetlands for their exis- tence and there is an annual loss of from 16.5 to 40 square miles of wet- land in some parts of coastal Loui- siana. Although natural causes have been responsible for some marsh sub- sidence and erosion, most of the losses have been attributed to man- caused actions . These actions include construc- tion of federally financed navigation channels, Mississippi River levees, flood control reservoirs, canal dredging and spoil disposal associat- ed with oil and gas access, and drainage of wetlands for agriculture. Saltwater intrusion has changed much of the brackish and freshwater marsh to salt marsh. Although the total catch of oysters and shrimp has not decreased significantly, more effort is being expended to attain these catches . The catch per shrimp boat has decreased from 44,000 pounds in 1945 to less than 5,000 pounds in 1972. The production per acre of oysters has decreased from 500 pounds in 1945 to about 75 pounds in 1972. The FWS introduced a plan to re- introduce fresh water into marshes in 1959. The Service also recommended that the Mississippi River and Tribu- taries Act of 1928 be amended to in- clude diverting river flow into these estuarine habitats. The act was amended in 1965 but no major federal- ly funded measures have been con- structed. The FWS through the Divi- sion of Ecological Services, is as- sisting the Corps of Engineers in developing this program. The FWS calculated that one structure alone would result in annual benefits of between $4.4 million and $5.2 mil- lion. The Atchafalaya River embayment is the only major area in Louisiana where a delta is developing on the 26 Louisiana coast. We are working with the Corps of Engineers to maximize delta development in Atchafalaya Bay when navigation maintenance and de- velopment work is required. We have excellent opportunities to reintro- duce fresh water into several marshes with this effort. I want to commend the Louisiana Legislature for directing the Loui- siana Department of Transportation and Development to prepare a fresh- water reintroduction plan. With both State and Federal efforts, we are optimistic that we can retard the loss and develop more Louisiana marsh habitat. The restoration of Louisiana wetlands will be of significant val- ue for hurricane protection, pollu- tion control, nutrient cycling, and flood control. Many of the measures we are recommending to benefit fish and wildlife have benefits to people as well, but they have not been ade- quately quantified. The freshwater inflow to estua- ries issue is more complex along the Texas coast of the Gulf of Mexico than in Louisiana for several reasons : Many rivers are involved in Texas while in Louisiana most of the freshwater flows to estu- aries comes from the Mississippi River and its distributaries. The Texas coast rainfall ranges from semi-arid levels in the Brownsville and Corpus Christi area to relatively high levels around Galveston and Houston. Great natural differences in rainfall occur between wet or hurricane years and dry or arid years . The competition for the use of water is intense in Texas be- cause of irrigation development, population and industrial growth. Much of the industrial growth is concerned with energy production, one of our Nation's primary problems. Water avail- ability is a primary deterrent to increase agricultural and industrial growth in Texas. The State of Texas has been dealing with the freshwater inflow to estuary problems effecttively from the standpoint of data collection and the development of predictive models. The freshwater needs of six estuarine areas have been quantitatively de- scribed in a study conducted by the Texas Water Resources Department that has been submitted to the Texas Leg- islature. Therefore, the people of Texas recognize the need for provid- ing freshwater inflow to sustain estuarine ecosystems if they expect estuaries to produce shrimp, oysters, fish, or waterfowl in the future. The FWS has several programs along the Texas coast that involve freshwater inflow to estuaries: The FWS considers the Texas coast to be one of the highest priority areas in the U.S. when it comes to preserving habitat for endangered species and for wintering migratory waterfowl and other birds. The coastal national wildlife refuges fur- nish part of these habitat needs but we intend to use all our re- sources to protect additional habitat through identifying and providing information on fresh- water inflow needs and habi- tat values, and by making sound scientific recommendations in our Coordination Act reports. 27 We have conducted freshwater in- flow and field studies in the Nueces-Corpus Christi estuaries and have an ongoing freshwater inflow study in the Matagorda Bay system. These studies, costing over $1.2 million, will assist us in providing techni- cally sound recommendations on freshwater inflow needs of se- lected estuaries. We believe that the best possible technical information and methods should be made available to state and Federal agencies and to persons responsible for making decisions on freshwater inflow. We are particularly concerned with the effects of industrial development and water use in rivers that flow into the Gal- veston Bay ecosystem. If we can conserve a significant part of the fish and wildlife habitat in the biologically productive Galveston Bay ecosystem, we will have accomplished much. We be- lieve that a comprehensive water management plan that considers industrial, urban, agricultural, and fish and wildlife needs should be prepared for this heavily populated growing area. If such a plan is properly pre- pared and accepted by State, Federal, and local governments, it would assist everyone in carrying out their responsibili- ties for preserving this impor- tant estuarine habitat. More important, it would make the Houston-Galveston area a more attractive place to live in and enjoy. The Service is going to continue to exercise all measures within its power to ensure that adequate fresh water is provided to sustain the estuarine ecosystems on the Texas coast . Probably no estuary in the United States has been changed more by man than the San Francisco Bay. The ecosystem extends from San Fran- cisco Bay to the Sacramento-San Joaquin Delta. The degradation pro- cess in the area started with hy- draulic gold mining in the 1800' s. Next, tidelands were filled for urban and industrial development. Pollution from the growing population and from industry intensified the problem. Finally, increases in agriculture and urban development led to massive wa- ter diversion. The bay ecosystem was impacted by a combination of reduced volume of freshwater inflow, filling in of the bay, and reduced water quality. The bay ecosystem provides recreational, scenic and aesthetic benefits to over 5 million urban and suburban residents. The inflow into the bay is now only half of the nat- ural amount and it is expected that the inflow will decrease by another 50 percent by the year 2000. Fish and wildlife resources and habitats have decreased significant- ly: In the San Joaquin River the en- tire spring chinook salmon run has been lost and the fall run is only 10 percent of its his- torical size. The chinook sal- mon run in the Sacramento River is about 40 percent of its size in 1953. Between 1960 and 1979, the striped bass population has de- creased by over 50 percent. Wa- ter diversion and saltwater in- trusion are the assumed causes of this decline. 28 Approximately 95 percent of the original 850 square miles of natural tidal marshes in the bay complex have been filled or lost. The remaining tidal marshes--about 43 square miles --contribute over 11 thousand tons of carbon annually to the San Francisco Bay estuary. Suisan Marsh furnishes about 25 percent of the wintering habitat for waterfowl in the Pacific Flyway and we have lost over 80 percent of the area of this marsh alone. Water diversions for agricul- ture, urban and industrial needs by Federal and State agencies and by private developers have been the main causes for these fish and wildlife resource losses. What has the FWS been doing to prevent further deteri- oration of this ecosystem? We have been handling our Coordination Act activities since the 1950' s, but un- til recently our effectiveness has not been good. We have received sup- port from private conservation groups, the State of California and other Federal agencies. The Califor- nia State Water Board provided a Wa- ter Right to protect striped bass and Suisun Marsh in 1978. Presently a four-agency group — California De- partment of Fish and Game, California Department of Water Resources, U.S. Water and Power Resources Service, and the Division of Ecological Serv- ices in the U.S. Fish and Wildlife Service—is attempting to work out satisfactory solutions to protect the remaining habitat. We would like to have a comprehensive water plan de- veloped that would include fish and wildlife water needs along with agri- cultural and urban needs. We are developing better data and methods for predicting impacts. We need to We need to conserve and enhance the remaining fish and wildlife habitats in the San Francisco Bay ecosystem. Heavy public involvement is essential and we are optimistic that progress is being made. An outstanding example of our progress is the Secretary of the Interior's support of instream flows for the Central Valley Project for the improvement of the delta marshes and San Francisco Bay ecosystem. A departmental draft EIS is currently undergoing public review that pro- poses legislation to reauthorize the Central Valley Project to save delta water quality and fish and wildlife needs on a permanent basis. Freshwater inflow problems have also been identified in several other estuaries along the Atlantic coast, in the Gulf of Mexico, Southern Cali- fornia, in the Pacific Northwest, and in Alaska. Particularly in Alaska, we have the opportunity to bring the freshwater needs of estuaries into the early stages of planning. Even though water allocation has not be- come a front line issue on the Atlan- tic coast, the issue will have to be addressed within the next 10 years. There are certain general obser- vations that I would like to em- phasize in concluding my remarks. First, many of the measures we are recommending to benefit coastal fish and wildlife resources will serve other functions as well, such as hurricane protection, water puri- fication, contaminant removal, and flood protection. Although direct economic benefits to man have not been quantified, they are real. As an example, it is cheaper and less energy intensive for natural pro- cesses to clean water than to use 29 expensive systems . waste water treatment Second, while there is a short- term ebb and flow, there is a strong trend in the Congress and from pri- vate and governmental groups living around our major estuaries that fa- vors a stronger environmental ethic and that state, Federal and local governmental groups are working to- gether more so than in the past. Public pressure is demanding this action and we hope it continues. sive planning. Although land and water planning appears to be anathema to the American way of doing things , we cannot protect important ecosys- tems in our estuaries without it. Comprehensive planning requires the integration of inland river and coastal planning. Fourth, we need to improve our capability to predict the effects of various amounts and qualities of freshwater inflow on estuarine eco- systems . Third, we need to develop com- prehensive planning procedures that will force us to consider the water needs of our natural ecosystems along with domestic, agricultural, and industrial water needs. We cannot address the problem of cumulative im- pacts effectively without comprehen- Finally, the Fish and Wildlife Service is going to take every mea- sure possible to preserve, protect and expand the estuarine habitat of our Nation. I am sure that this sym- posium will develop some innovative and practical ideas to assist us. 30 FRESHWATER INPUTS AND ESTUARINE PRODUCTIVITY Scott W. Nixon Graduate School of Oceanography, University of Rhode Island Kingston, Rhode Island ABSTRACT The processes responsible for the high level of production char- acteristic of estuarine systems are not yet well understood. There are at least five major hypotheses which have been put forward at various times to account for estu- arine production, including the fertilizing effect of nutrients in fresh water, advection of nutrient rich offshore water, the trapping of nutrients in estuarine circula- tion, the outwelling of nutrients from salt marshes and other wet- lands, and the rapid recycling of nutrients within the estuary. The remarkable similarity of primary and (to a lesser degree) secondary production levels among estuaries with widely varying fresh water in- puts, hydrodynamics properties, and geographical and geological charac- teristics suggests that a more gen- eral feature of estuarine systems is most important in enhancing pro- duction in these areas. While river inputs may contribute to the spring bloom, most of the production in many estuaries appears to take place during the warmer months and to be supported by recycled nutri- ents. Two characteristic features of estuarine systems are their shal- low depth and relatively strong mixing. Both of these features con- tribute to a relatively complete and rapid coupling of heterotrophic and autotrophic processes in estua- ries. Because remineralization appears to be a slower process than the formation of new organic matter, it may be that heterotrophic process- es play an important role in regula- ting the primary production of es- tuaries, and that the similarity of carbon fixation rates in various estuaries arises because of some common limit on the rate of nutrient recycling. More attention also needs to be given to the problem of understanding the relationship between short-term processes, such as annual production or regenera- tion, and longer-term processes, such as the continuous input of nutrients from rivers and anthro- pogenic sources. THE NATURE OF THE PROBLEM - WHY ARE ESTUARIES SO PRODUCTIVE? Estuarine systems are usually characterized by levels of primary production per unit which are con- siderably higher than those typical of offshore waters (Table 1). In many cases, the higher production of estuarine and nearshore waters has been attributed either direct- ly or by implication to the ferti- lizing effect of river inputs of nitrogen, phosphorus, or silica. The river appears to be the principal source of nitrogen and phosphorus in the estuary (Forge River, Moriches Bay, L.I.), (Barlow et al. 1963). 31 Table 1. Estimates of annual primary production in estuarine, nearshore, and offshore waters along the U.S. east and gulf coasts. Area Production 2 (g C/m /yr) New York-New Jersey Lower Hudson Estuary 820 (690-925) Mouth of the Estuary 640 N.Y. Bight Nearshore (<8 km) 420 N.Y. Bight Apex 370 Continential Shelf (<50 m deep) 160 Continental shelf (100-200 m deep) 135 Edge of shelf ( >1000 m deep) 100 r ■ b Georgia Inshore behind barrier islands 300 Continental Shelf (<20 m deep) 285 Continental shelf (20-200 m deep) 130 T ■ • c Louisiana Barataria Bay 360 Nearshore shelf 265 Gulf of Mexico 35 aRyther and Yentsch 1958; Mandelli et al. 1970; Malone 1976; O'Reilly et al. 1976; Thomas et al. 1976a, 1976b. bHaines 1979 CE1-Sayed et al. 1972; Day et al. 1973; (macrophytes and phytoplankton) ; Sklar 1976 32 The distribution of nitrate in the upper Chesapeake Bay. . ..suggests that the inflow of the Susquehanna River. . . is the major source ... (Carpenter et al. 1969). The high fishery productivity of the water adjacent the river mouth is a result of nu- trient contribution by the Mississippi River... (Ho and Barnett 1977). River inflow is clearly a ma- jor source of substances to the estuary (San Francisco Bay) ... (Peterson 1979). Conclusions such as these seem in- tuitively correct because the con- centrations of nutrients, particu- larly inorganic nitrogen and sil- ica, are usually much higher in fresh water than they are in coast- al sea water (Figure 1). But the situation is more interesting than it first appears, and even this simple relationship may be re- versed. For example, in their stud- ies of one of the world's major riv- ers, Ryther et.al. (1967) found that: In the surface water influenc- ed by the Amazon River compared with the surrounding seawater, the concentrations of nitrate, phosphate, and planktonic organ- isms were lower while the levels of silicate were appreciably higher. The direct over all ef- fort of the river, therefore, is to decrease the fertility of the ocean into which it flows. low that the higher concentrations of nutrients normally found in riv- ers will make freshwater inputs a major factor in estuarine nutri- ent dynamics. And it will require considerably more than a descrip- tion of the freshwater-saltwater nutrient concentration gradient to properly assess the role of fresh water in enhancing the productivity of estuaries. I think it is important to realize how confused we still are about this fundamental problem of estuarine (and nearshore) produc- tivity, and how far we still are from a full understanding of coast- al marine nutrient dynamics. If we keep our sense of humor and some perspective on the real com- plexity and challenge of the problem, it can be humbling and amusing to watch ecologists arguing that salt marshes are valuable because they "outwell" nutrients (which suppos- edly make the estuary productive) and because they provide "tertiary treatment" which removes nutrients from the estuary which supposedly are making it eutrophic (Nixon 1980) . In a symposium focusing on the importance of freshwater in- puts, the tendency is to emphasize the role of rivers in bringing "good" nutrients into the estuary. But in another context the emphasis is likely to be on the harmful ef- fects of "bad" nutrients from sew- age or agricultural runoff. FRESHWATER INPUTS AND OTHER HYPOTHESES While the behavior of the Ama- zon may be a remarkable exception, it still does not necessarily fol- Given the present state of know- ledge, it should not be surprising that a number of alternative hypothe- ses have been developed which attempt 33 O cr o o UJ > -J o C/> C/> 2 o 20 - 10 - 30 - 20 - 10 - MID NARRAGANSETT BAY BLACKST0NE RIVER (xlO)* /\ A A* \ "\s> •g' VXHARLESTOWN^p °J&ND °£ i — i — \ — i — i — i OFF SUSQUEHANNA / RIVER MOUTH , UPPER CHESAPEAKE / BAY / / A /.a T-7-1 — 1 — 1 / \ PAMLICO "RIVERS" / \ / \ ' ^ Figure 1. Dissolved inorganic nitrogen concentrations over an annual cycle in the fresh, estuarine, and inshore marine waters of three estua- rine systems on the Atlantic coast of the United States. Data from Nixon (unpublished) and Nixon and Lee (in press)for Narragansett Bay; from Whaley et al. (1966) for Chesapeake Bay; and from Harrison and Hobbie (1974) and Thayer (1974) for the Pamlico River and Sound. 34 to account for high estuarine produc- tivity without calling for a fertili- zation of the estuary by river in- puts. In general, there are four major themes other than freshwater input which appear in the litera- ture, and I think the quotes given below will give a good feel for the diversity of opinion they represent. 1. Fertilization by advection of deeper offshore waters General conclusions are that the usual pattern of exchange between inshore and offshore waters tends to enrich the coastal zone irrespective of enrichment by freshwater drainage. .. (Riley 1967). 2. Fertilization by marshes Apparently, large rivers do not have as great a local effect on the productivity of estua- ries and coastal waters as was once assumed. I think the most important discovery we have made in our 15 years study of production dynamics on the Georgia coast is that the high fertility of this region is self-produced with- in the salt-marsh estuary, and is not due to nutrients wash- ed down the rivers (Odum 1968). 3. Fertilization by concentration - the nutrient trap In estuaries fresh water de- rived from the land... mixes with sea water and is carried seaward in the upper layer of the embayment. A counter-cur- rent of sea water moves in from the outer sea to replace that entrained in the surface outflow. .. consequently , the redistribution of nonconserva- tive elements by the sinking of organized matter will tend to cause the concentration of N to increase upstream rela- tive to the motion of the sur- face layer. The estuarine circulation creates a trap in which nutrients tend to accum- ulate. (Redfield et al 1963). 4. Fertilization by rapid recycling . . .For the Georgia and South Carolina shelf, nutrient in- flux to the coastal zone via outwelling is of minor im- portance, mixing of deep water across the edge of the shelf is of minor importance, and in situ regeneration is the most important process in maintaining high rates of nu- trient flux and hence high rates of biological produc- tivity in the shelf waters. (Haines 1975). Each of these mechanisms deserves a serious consideration that is beyond the scope of this paper. But as a start, the various possi- bilities can be brought together in a conceptual model (Figure 2) , and we can begin to focus on fresh water input as one of at least five alternative explanations for estu- arine production. It may be, of course, that different explanations apply to different estuaries or that estuarine productivity is a consequence of all of these things happening together, a conclusion reached by Correll (1978) in his recent consideration of the problem: Thus, estuaries maintain high production by maintaining high nutrient levels in bottom sed- iments and water column. This is done by nutrient/plankton trapping via the "salt wedge" 35 A A SEWAGE RUNOFF D D D D d o o a o a a a anno A 00 Q 0 a a o 0 n n -'^"...v WETLANDS Figure 2. Conceptual model illustrating five common hypotheses concerning the factors responsible for bringing about high levels of estuarine primary production: 1) The estuarine nutrient pool (B) is simply fertilized by fresh- water input (A) which may or may not include anthropogenic inputs; 2) Nutrient- rich deep water from offshore (D) is brought into the estuary (E) by the estu- arine circulation pattern where it is rapidly mixed up into the euphotic zone (B) by strong tidal and wind effects; 3) The estuarine nutrient pool is ferti- lized by inputs to rivers (A) and the estuarine tidal waters (B) by outwelling of nutrients from fresh and salt marshes and other wetlands; 4) Nutrients in the estuary (B) are taken up by the estuatine plankton (B) which fall to the deeper water (E) and are carried back upstream by the landward flowing bottom water where they are entrained in the seaward flowing fresher surface water (A) and can be taken up once again by the estuarine plankton (B) and; 5) In- puts to (B) from (A) and (D) are much less important than the recycling of nutrients within the system (B,E,F). 36 OJ 4-1 o CO 03 O o xi 4-1 a o CO u 0) > •H U u o ■—1 M £ O 0) u y. 3 O) /■— , -5 -3' 4-f i-H O o d <-> O CO 4-> g s w •H X o en i-i CO ■d ^ ° • H h a <=> to d •H s 01 OJ u 3 M o u 37 countercurrent and the nutrient modulating actions of tidal marshes, bottom sediments, and submerged vascular plants. It is difficult to argue with the proposition that estuaries are high- ly productive because of all the things that make them estuaries, but it would be nice to know a bit more about the relative importance of the different features of estu- aries in this regard. Similarly, it may finally be true that each estuary represents a unique set of processes coming together in a spe- cial way to result in a particular level of production. But before having to treat each estuary separ- ately, I think the most useful course to begin with is to press hard for a general model or concept. If various unified views can be stated, and shown to fail, then we can al- ways fall back on the diversity and uniqueness of nature for an expla- nation. SOME OBSERVATIONS ABOUT FRESHWATER INPUT There are at least three char- acteristics of river input that are of interest in trying to assess the importance of this feature in gen- eral estuarine productivity, includ- ing the magnitude of water flow, the concentration of nutrients in the water, and the seasonal varia- tion of each. THE MAGNITUDE OF FLOW It is clear that the amount of fresh water being discharged along the coast is extremely variable (Figure 3) . The influence of this discharge on the salinity of the estuarine receiving waters, however, is more complicated, because that parameter also reflects the volume of the estuary, the tidal prism, and the mixing and flushing characteristics of the system. In general, however, all of these features seem to combine with freshwater inputs to produce estuaries with lower mean salinities along the southeast and gulf coasts of the United States (Figure 4) . It is very difficult to know if this apparent trend is real or if it arises simply because of the location of sampling stations on the various estuaries. If it is real, it would seem reasonable to expect that the influence of fresh water might be greater in these estuaries and that they might therefore be quite dif- ferent from more northern systems in their productivity if freshwater in- put is important in this regard. NUTRIENT CONCENTRATIONS As far as I am aware, there are remarkably few reliable measurements of the major nutrients in rivers flowing into estuaries and even fewer which include a total inventory of all of the major forms of the nutri- ents over an annual cycle. While documents summarizing the ionic composition of many substances of geochemical interest are available (e.g. Livingston 1962), the apparent variability and scarcity of data on nutrient chemistry seem to have ef- fectively prevented anyone from put- ting together a credible geographical summary. The problem is further complicated by the development of agriculture or the location of large urban areas along the lower reaches of many rivers, so that the anthro- pogenic contribution to the riverine nutrient load can be very large and extremely variable from estuary to estuary. The resulting expectation 38 o o < < Z> < UJ t \J 30 • • • • • • • • • • • • • • • • 'TEXAS ' /COAST/ ' o 1 1 / \° / \ / V 20 — • H • • • • • • 10 — • • • • 1 • 1 -. 1 • • 10 15 20 MEAN ANNUAL TEMPERATURE, °C 25 Figure 4. Mean annual surface water salinity and temperature at 46 estua- rine and nearshore sampling stations reported by the U.S. Department of Commerce (1960). The length of record varies. 39 (though based on little evidence) is that the amount of N, P, or Si being delivered to various estuaries ought to vary considerably (Jaworski, in press), and that if this feature is important in regulating primary pro- duction, it might also be expected to vary widely. SEASONAL VARIATION The inflow of freshwater varies seasonally to a greater or lesser degree in different estuaries as a function of rainfall, temperature, and watershed size and character- istics. In many (perhaps all) estuaries, a higher rate of freshwater input is associated with a higher rate of nutrient in- put as well, but because there is often some dilution of concentra- tion during periods of higher dis- charge, the total flux of nutrients may be more constant during the year than a simple inspection of the yearly discharge cycle may suggest. Overall, however, periods of high discharge will bring about an accumulation of fresh (presum- ably high nutrient) water in the estuary and result in a lowering of the salinity. The annual varia- tion in salinity differs consider- ably among estuaries for all of the reasons mentioned previously, but an excursion of 5 to 10 percent is not uncommon (Figure 5). If river input is important in driving the primary production of the estuary, we might expect to see some en- hanced production associated with this period of increased discharge and/or lowered salinity. SOME OBSERVATIONS ABOUT ESTUARINE PRODUCTION REGIONAL VARIATION - A COMPARISON OF SYSTEMS Primary Production In reviewing the various stud- ies of primary production in estu- arine systems, I have been impress- ed by the remarkable similarity of virtually all of the annual estimates (Table 2). With few exceptions (such as the highly eutrophic lower Hudson River), there appears to be somewhere between 150-400 gC/m /yr fixed in shallow coastal waters when an average is made over a whole estu- arine system. Values higher than these are certainly found in seagrass and seaweed beds, but when their pro- duction is apportioned over the whole estuary and added to the lower area-based phytoplankton pro- duction that is usually found in such shallow waters, the total pro- duction seems to fall in with that found in deeper plankton-based systems. The same may be true of estuaries with very productive in- tertidal or shallow subtidal ben- thic diatom communities, though there are too few measurements of this component to generalize with any confidence. It seems to me that this small variation in pro- duction (approximately a factor of 2-3) compared with the very large range in estuarine freshwater input (orders of magnitude) suggests that it is some other, more constant 40 40 r o o^ 30 >- < < LxJ NEWPORT, RI 20 10 PORTLAND, ME PORTSMOUTH, NH SOLOMONS MO 0 1 EUGENE I, LA i L_ -5 0 5 10 15 20 25 30 MONTHLY MEAN TEMPERATURE, °C Figure 5. Variation in mean monthly salinity and temperature in the surface waters at nine estuarine sampling stations along the Atlantic and gulf coasts of the United States (U.S. Department of Commerce I960) Length of record varies. 41 Table 2. Estimates of particulate primary production in some U.S. and Canadian estuarine and nearshore waters. Area Primary Production (g C/m /yr) Bedford Basin, N.S. (Piatt 1975) 220 St. Margaret's Bay, N.S. (Piatt 1971; Mann 1972 a,b) 790b Narragansett Bay, R.I. (Furnas et al. 1976) 310 Charlestown Pond, R.I. (Nixon and Lee, in press) 140 Block Island Sound, R.I. (Riley 1952) 285 Long Island Sound, (Riley 1956) 205 Hempstead Bay, L.I. (Udell et al. 1969) 215b Peconic Bay, L.I. (Bruno et al. 1980) 190 Lower Hudson Estuary, N.Y. (O'Reilly et al. 1976) 690-925 New York Bight Apex (Malone 1976) 370 Patuxent River, M.D. (Stross & Stottlemeyer 1965) 210 Chincoteague Bay, M.D./V.A. (Boynton 1974) 180 Pamlico River Estuary, N.C. (Kuenzler et al. 1979) 200-500 Inshore Sounds, N.C. (Dillion 1971; Thayer 1971) 345b North Inlet, S.C. (Sellner et al. 1976) 260 Salt Marsh Creek, G.A. (Turner et al . 1979) 90 Inshore Sounds, G.A. (Haines 1979a.) 300 Off Altamaha River, G.A. (Thomas 1966) 550 Nearshore Shelf, G.A. (Haines 1979a.) 285 Barataria Bay, L.A. (Day et al. 1973) 360 Nearshore Louisiana (Sklar 1976) 265 Columbia River Mouth (Anderson 1964) 80 Puget Sound, W.A. (Winter et al. 1975) 465 Burrad Inlet, B.C. (Stockner and Cliff 1979) 350 Kaneohe Bay, H.I. (Smith 1981) 165 Phytopl ankton only unless otherwise noted St. Margaret's Bay phytoplankton = 190; seaweeds = 600 Charlestown Pond phytoplankton = 30; benthic plants (not included seaweed) = 110 Hempstead Bay phytoplankton = 198; benthic plants = 17 North Carolina sounds phytoplankton = 70; benthic plants = 275 Barataria Bay phytoplankton = 165; benthic plants = 195 42 feature of estuarine systems that makes them so productive. The same could be said of the importance in this regard of salt marshes or estu- arine circulation patterns, both of which are features which vary widely among estuaries (Nixon 1980; Kjerfve et al. 1978). Secondary Production It is reasonable to ask if the similarity of estuarine primary pro- duction is reflected in a relative- ly small range in secondary produc- tion. Unfortunately, the great difficulty of obtaining measure- ments of the rate of production of higher trophic levels has made it impractical to answer this question directly. The best we may be able to do is to estimate the relative production of animal biomass in estuaries through the use of fish- ery yields. It is always risky to use landings data because of sam- pling problems and a number of other difficulties. Nevertheless, these data represent the best comparative information available and, after reviewing the fisheries yield data for a large number of lakes, Ryder (1965) concluded "that catch is a reliable estimate of fish produc- tion despite the variables affect- ing it." As far as I am aware, however, it is not known how good fish production is as an indicator of total secondary production. There are at least two ways to address the problem. First, the yield of a given estuary can be compared with its freshwater input as they vary from year-to-year and, second, the yields of various es- tuaries with different levels of freshwater input can be compared. In looking at variations over time in the Gulf of St. Lawrence region, Sutcliffe (1972, 1973) was able to find a strong positive correlation between river discharge and the catch (after appropriate time lags) of var- ious species. A similar positive re- lationship was reported by Turner (1979) for oyster landings in Mobile Bay, Alabama. However, an analysis of five years of total commerical landings data from five estuaries on the Texas coast provided more ambig- uous results which Armstrong (1980) interpreted as showing a curvilinear relationship with an optimum rate of freshwater input. In the case of shrimp, on the other hand, it appears that there is a strong negative lin- ear correlation between freshwater input and production if one compares the mean annual salinity of Lake Pontchartrain with the Louisiana landings (Turner 1979). A similar relationship appears to be evident, particularly over the past 30 years, between Mississippi River discharge and Louisiana shrimp landings (Bar- rett and Gillespie 1973; White and Boudreaux 1977), though there are other, longer-term cycles and trends in the shrimp data as well (Figure 6). But there appears to be little, if any, relationship between the dis- charge of the Mississippi and the production of the other major com- mercial species in coastal Louisiana (Figure 7). A cursory examination of landing records from Chesapeake Bay also failed to show any simple rela- tionship with discharge from the Sus- quehanna River, the major freshwater input to that system. Regional Variation If different estuaries are com- pared, it does not seem to me that the results show any relationship between yield and freshwater input (Table 3). An earlier comparison of seven Texas estuaries by Chap- man (1966) reached the opposite con- clusion, and he may be correct for the special conditions along the south Texas coast. However, there 43 Table 3. Annual landings (kg/h) a of finfish and shellfish from various U.S. estuaries . Estuary Reference Finfish Shellfish Total Narragansett Bay (1880) Near shore Rhode Island (1975) Long Island Sound (1880) Long Island Sound (1975) Peconic Bay, L.I. (1880) Gardiners Bay, L.I. (1880) Moriches Bay, L.I. (1880) Great South Bay, L. I. (1880) Jamaica Bay, L.I. (1880) Delaware Bay (1880) Delaware Bay (1975) Chesapeake Bay (1962) Chesapeake Bay (1975) Inshore North Carolina (^1945) Apalachicola Bay, F.L. (1966) Inshore Louisiana (%1975) Barataria Bay, L.A. (%1970) (1) (2) (3) (4) (5) (5) (5) (5) (5) (6) (7) (8) (7) (9) (10) (11) (12) 63 40 103 80 31 111 138 8 146 29 15 44 85 8 93 71 8 79 149 58 207 110 282 392 67 51 118 7 1 8 1 6 7 142 12 154 132 33 165 44 13 57 24 54 78 113 41 154 22 170-440 192-264 1. Clark 1887a 2. N.M.F.S. Area 539, W. Hahm, National Marine Fisheries Service, Woods Hole, Massachusetts 3. Clark 1887b 4. N.M.F.S. Area 611, W. Hahm, National Marine Fisheries Service 5. Mather 1887 6. Collins 1887 7. National Marine Fisheries Service 1975 8. McHugh 1967 9. Taylor et al. 1951 10. U. S. Department of the Interior 1970 11. Bahr et al. 1979 (unpublished manuscript) 12. Day et al. 1973 44 o o I-* sqi gOl'SONIONVl dlNldHS o o o co *c ^r 1 i 1 ___ l--o 1 1 1 o " °- — ~ ~ o- — -_ _ o" — =0 — _ _ — "6 0"~ "" \ o^ __ — ~"~o- _ __ ~-o o~ ~~ ~- — -o 0 _ --o - o- — _ — — ■io -o — " **" ^^^ - ,o- -" ' o: ^o UJ "~ ^o «C^ o o — " cr o 1 vHosia o ^>- °c 0 T ~ ~ ~ o — 1/ cr I CO 1 1 1 1 — p ' : 1 ~~ — o 1 m m 10 m in in m fO en O m ro O m cvj o in m £01 x |-S £w 439dVHDSI0 "IV0NNV NV3IN !■ S-l J3 to a o h-1 T3 CI CO Sj > •H OS •H & Cb •H CO (0 •H W W OJ O oo S-l u Cfl C C CO d (LI s > i m m CVJ 0) < \o w 00 c oo c •H )-l d tn 4-> d d ■H d oo o s-i O 01 2 0) •H XI p. > 4-> 4-> •H O o S-l 3 d s—\ o XJ 'H co I — 1 o >> e s-i -a S-i ■ — ft > S-l 4-1 oo •H l-l S-l O W E HI n) a, CD g > S ft P. •H ■h 3 S-. U 00 o P-l ■ — 1 a; j3 +-> d cu d oo -H o S-l w -d (0 4-1 s-i s u d d cu oo o S-l +j ■H d S-l •H 0) 4-1 To- >> as ll S-l s ~J a) « 3 S-l 1— 1 4-1 u 3 a> > s aj •H 3 CC u CJ 01 in CO >> OC (LI U 4J -• '-1 ■-i 00 co Zh O K < to cr u MISSISSIPPI RIVER /% 00 O < X z UJ "A/ OYSTERS 1950 I960 1970 1980 Figure 7. Mean annual discharge of the Mississippi River compared with the Louisiana landings of some estuarine species of major commercial importance. 47 PRIMARY PRODUCTION •— • CHL o STANDING CROP0""0 SOLAR RADIATION d3 TEMPERATURE t£3 RIVER FLOW c£3 100 -i "1I9.0°C 2 52 m3s"' NARRAGANSETT BAY, R.I. " °-l 280°C PATUXENT RIVER, MD 280°C t — i — i — i — i — i — i — i — i — n- COR E SOU N D , N.C. " :«JlK"'' -r~i — i — r~i — i — i — i — i — i — i~i -t~i — mi — n — i i i — i i i"^ l"f "i ' i "i "i i — i — i — r ■ 'f ' T ' U. NEAR-SHORE GEORGIA BIGHT " 100 -i 28.7°C I I I I t T 'I'T'I'T'I BARATARIA BAY, LA 9.3°C J' M' M J' COLUMBIA RIVER MOUTH Figure 8. Comparison of the relative seasonal distribution of solar radia- tion, water temperature, freshwater input, phytoplankton primary production and phytoplankton chlorophyll a (CHL a) in six estuarine and nearshore en- vironments over an annual cycle. Maximum values from which the normalized distributions were calculated are also shown for comparison. Data from sources in text (especially Table 2 and Figures 1 and 2) except as follows: Solar radiation, five-year mean from Climatological Data, National Summary (U.S. Dept. of Comm. , Ashville, N.C); Narragansett Bay plankton data from Durbin et al. (1975); Georgia Bight plankton from Haines and Dunstan (1975). 48 FRESHWATER INPUT AND ESTUARINE PRODUCTIVITY In a few systems, measurements have been made of the annual input of nitrogen from fresh water and other sources and of the annual pri- mary production in the estuary. If a Redfield (1934) model of stoichio- metry (106C:l6N) is used to calculate the amount of nitrogen required to support the annual production, it ap- pears that, with the exception of some highly eutrophic areas, most of the production must be sustained by recycled nitrogen (Table 5) . It may well be that the input of nutri- ents from fresh water may make some contribution (perhaps an important one) to spring bloom, but for most estuaries, most of the production takes place in the warmer months when recycling is much more important than inputs. I think we will con- tinue to find that this is a gen- eral feature of estuarine systems (Nixon 1981), and it helps to explain why estuarine primary pro- duction and, to a lesser degree, secondary production levels are so similar. It also helps explain why no one has yet developed dia- grams relating nitrogen loading rates to estuarine production as the limnologists have done so suc- cessfully with phosphorus loading in lakes (Vollenweilder 1976; Schin- dler 1981). The feature that estuaries have in common, and that sets them off from the sea, is that they are shal- low. They may have large rivers, or small rivers, or no rivers at all; they may have a great deal of salt marsh or very little; they may have grass beds or seaweed beds or phytoplankton, but they all have their zones of decomposition and nutrient regeneration (both pelagic and benthic) near the euphotic zone. Moreover, there is usually strong vertical mixing from tides and wind to assure that the coupling of de- composition and production is ef- fective. I think it is worthwhile to put forward the hypothesis that the high production of estuarine waters in general is brought about and maintained by the almost com- plete and rapid coupling of hetero- trophic and autotrophic processes. Moreover, if the relative rates of organic synthesis and decomposition are considered, it seems likely that the upper limit of production is set, for the most part, by the slow- er rate of remineralization. If so, one of the important features of an estuary may be the relative impor- tance of pelagic versus benthic re- mineralization, because the rate of these processes is quite different. The most rapid way to recycle nu- trients is to put the organic mat- ter through pelagic animals, such as microzooplankton. But we need to learn more about the processes of decomposition in the water and in the sediments. Ecologists, like the rest of society, have been pre- occupied with production and growth, with the input and consumption of "new" materials. We need to attend more to what Odum et al. (1977) have called the "regenerative half" of our systems. Now, having said all of that, I must admit to being uncomfortable that the discussion so far has cen- tered on short-term measurements and perspectives. We also know very lit- tle about the long-term effects of nutrient input to estuaries. In the short-run, primary production may appear to be supported largely by recycled nutrients, but in the long run, are nutrients being concentrated in the estuaries? Is the recycling rate higher in estuaries with greater input? The similarities of the pri- 49 Table 5. Comparison of the estimated amount of nitrogen required to support the observed annual primary production with the amount of nitrogen delivered to the estuary in freshwater inputs over the year. Area N for annual primary production/annual N input St. Margaret's Bay, N.S. (Sutcliffe 1972) 8.9' Narragansett Bay, R.I (Nixon 1981) 6.9 4.4 Long Island Sound CT. (Harris 1959) 20 aa Hudson River Estuary, N.Y. (O'Reilly et al. 1976, Duedall et al. 1976, Thomas et al. 1976a, 4-5 June 1974 1 day budget only) Pamilico River Estuary, N.C. (Kuenzler et al. 1979) 0.3 20 0.04 a Georgia Bight (0-20m) (Haines 1975) 111 San Francisco Bay, CA. (Peterson 1979) Kaneohe Bay, H.I. (Smith 1981) 1.3 0.6( ^a Freshwater flux includes inorganic nitrogen only ( includes only NCL ) Freshwater flux includes inorganic, dissolved organic and particulate nitrogen. "Freshwater flux includes inorganic and particulate nitrogen. Hudson River plus inorganic nitrogen in New York City sewage. 50 mary (and perhaps secondary) pro- duction suggest that this is not an important coupling, but we lack long- term data from estuaries, and it is not clear to me how short-term, rapid recycling of nutrients is linked to long-term inputs. The rivers have been flowing for a long, long time, and we know that most estuaries have been filling in with sediment in spite of a rising sea level. But, except for highly enriched urban areas, we do not know if they are also becoming more eutrophic. Fresh- water inputs may yet prove to play a role in the long-term fertility of estuaries . REFERENCES Anderson, G.C. The seasonal and geo- graphical distribution of pri- mary productivity off the Wash- ington and Oregon coasts. Lim- nol. Oceanogr. 9:284-302; 1964. Armstrong, N.E. Effects of altered freshwater inflow on estuarine systems. Fore, P.L.; Peterson, R.D., eds . Proceedings of the Gulf of Mexico Coastal Ecosys- tems Workshop, 1979, September 4-7, U.S. Dept. of the Interior, Fish and Wildlife Service, Port Aransas, TX. Albuquerque, NM: U.S. Fish and Wildlife Service; 1980:17-31. Bahr, L.M. , Jr.; Day, J.W. , Jr.; Stone, J.H. Energy cost-ac- counting of Louisiana fishery production. Baton Rouge, LA: Center for Wetland Resources, Louisiana State University; 1979 unpublished manuscript. Barlow, J. P.; Lorenzen, C.J.; Myren, R.T. Eutrophication of a tid- al estuary. Limnol. 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Develop- ment of an areal management con- cept for Gulf penaeid shrimp. New Orleans, LA: Louisiana Wild- life and Fisheries Commission. Tech. Bull. 22; 1977. Winter, D.F. ; Banse, K. ; Anderson, G. C. The dynamics of phytoplankton blooms in Puget Sound, a fjord in the northwestern United States. Mar. Biol. 29:139-176; 1975. 57 PLENARY PANEL POLICIES AND PROBLEMS IN DEALING WITH FRESHWATER INFLOW TO ESTUARIES Chaired by Mr. John Clark, Conservation Foundation 58 INTRODUCTION John Clark Conservation Foundation, Washington, D.C, Many years ago, the Conservation Foundation discovered that estuaries were a valuable resource; one that was vulnerable because of the inevi- table navigation, industrial, and general residential development that occurs along our shores. In a book produced during the late fifties by Lionel A. Walford--Living Resourc- es of the Sea--the Conservation Foun- dation made its pitch for the estuary as an endangered resource that vi- tally needed protection. The Founda- tion began an aggressive effort to protect wetlands and waters of estu- aries as intact resource units. One mistake made was to think that estu- arine conservation was largely a coastal problem. It may have been a coastal problem in the sixties when dredging and filling were occurring and wetland destruction was rapid. But now, with most of the worst of those destructive kinds of projects under control, we find that estuarine conservation is largely a water sup- ply problem dealing with the quanti- ty, the quality, the timing, and the rate of flow. This is where the scene has shifted and this is where we are going to have to work if we are going to protect estuaries. We have to know how much water is need- ed, what pollutants are tolerable, and at what times these waters flow into estuaries. As a result of this shift from concerning ourselves with the coastal area, to the water basin itself and the physical changes there, just about everything we have done in the conservation of estu- aries since 1965, when Congress started trying to get its estuarine legislation together, is all out of date. For instance, the Coastal Zone Management program in this country, which was fashioned to protect estu- aries, is powerless to cope with is- sues about water supply to estuaries. I don't know how many of you know it, but the first version of the Coastal Zone Management Act in 1969 and early seventies was known as the Estuarine and Coastal Zone Management Act. It was a resource protection initiative fashioned in Congress. Somehow in the next couple of years, before 1972, it got wrenched around strong- ly to becoming a land use oriented management act. Meanwhile, separate Federal programs and permit programs were devising some pretty good con- trols over dredging, filling, and wetland destruction. Because the Coastal Zone Management Act is power- less to do anything about water sup- ply, quantity, quality, and timing a new initiative is needed for estu- arine conservation. This initiative must have its roots in national water resources policy, not in coastal policy. This shadowy area is what Gary Wills calls the sunless marsh- lands of American politics. 59 FRESHWATER INFLOW AND CHESAPEAKE BAY Mark Bundy Maryland Department of Natural Resources, Annapolis, Maryland I am very pleased to discuss a few of the problems and policies associated with freshwater inflow to estuaries. Even though the subject is extremely broad and very diverse, I have directed my comments to the problems created from the competition between man and estuaries for fresh- water inflow. From the context of this presentation, I am using the term problem not to suggest an adverse effect as a result of change, but rather only to indicate that a change has taken place. The largest estuary in North America, of course, is the Chesapeake Bay. It is 695 miles long from the flats at the mouth of the Susquehanna River to its mouth at Hampton, Virginia. It varies in width from 4.2 miles to approximately 37.5 miles and contains an average of 18 tril- lion gallons of water. The total drainage area for the bay is approx- imately 64,000 square miles. Forty- two percent of this is the Susque- hanna drainage basin and another 22 percent comes from the Potomac River Basin. In all, the Chesapeake Bay drains six states and Washington, D.C. Of the total volume of fresh- water inflow, which averages approx- imately 69,000 cubic feet per second, the Susquehanna contributes 70 per- cent. There are approximately 2,700 species of mammals, birds, fish, and reptiles that have at one time or another been found around the bay. Among these are numerous species of resident and migratory fish and waterfowl which are dependent upon the Chesapeake estuary for all or a significant part of their life. The spawning of indigenous fish in the Chesapeake waters contributes greatly to the Atlantic coast stocks. This is especially true of striped bass. Researchers have estimated that 8 percent of the Atlantic coast strip- ed bass population is spawning in Maryland. As we are aware, the indigenous life associated with estuaries must share their water with our expand- ing human population. Recent esti- mates by the Army Corps of Engineers indicate that by the year 2020, the existing population around the Chesa- peake Bay will double. This will mean an increase from an existing eight-plus million population to over 16 million people, most of whom will be competing for their share of the water. Commercial fishing, maritime transportation, and a wide range of recreational activities are examples of man's various water-dependent ac- tivities. Estuaries are also expect- ed to provide water for municipal and industrial waste. This, of course, is not unique to estuaries. Rivers, streams, and lakes and the inland regions are also confronted with these demands. Man treats all wa- terways with equal disregard. Fish, waterfowl, and aquatic plants must also compete daily for their fair share. If we were to look at a map of the eastern United States, we would see that most major urban areas are located adjacent to an estuary. New York City on Raritan Bay, Philadelphia on the Delaware Bay, and the Newport News complex on 60 the Chesapeake are examples. There is no reason not to expect that these urban areas will not have the same or similar population increases as was already referenced for the Chesa- peake region. Recently much discus- sion has been given to an apparent trend in declining resources of the Chesapeake estuary. The temporary closure of the shad fishery, poor re- production of the oyster, reduced re- cruitment to the striped bass spawn- ing stocks, and significant declines in submerged aquatic vegetation have caused considerable concern. We are looking for explanations for these occurrences. Several research ef- forts have been directed at the prob- lems associated with changes in the inflowing fresh water. There is no need for any further discussion of these projects since several papers at this symposium will treat these subjects . Estuaries have both quantitative and qualitative problems associated with changes in freshwater inflow. Even estuaries with little or no urbanization in their watersheds have freshwater inflow problems, resulting primarily from natural events such as tropical storm Agnes in 1972 and Hur- ricane Allen earlier this year which carried large amounts of sediments to Chesapeake Bay. In estuaries that are highly urbanized, man's influence has exacerbated these problems. Let's now examine these problems a little more closely. Quantitatively, one of the first problems that we are con- fronted with is the restrictions to freshwater inflow. Restrictions can generally occur as a result of dams and weirs which are located primar- ily to provide water storage for municipal uses, electric power gen- eration, recreational uses, or agri- cultural purposes such as irrigation. Problems associated with these uses simply are a reduction of the amount of fresh water flowing into an estu- ary. A current example of one of the potential problems that exists in Maryland is the relicensing of the Conowingo Dam. The Conowingo is up for its fiftieth relicensing. As a part of this relicensing effort, a study is underway to determine what the minimum continuous discarge from the Conowingo Dam should be so that a condition can be placed on the license to ensure an adequate sup- ply-in particular for spawning fish such as shad and striped bass--of wa- ter below the dam. Another quantita- tive problem is the consumptive use of water for municipal and industrial purposes. Under normal conditions, these withdrawals are, perhaps, not as significant in the Chesapeake or on the east coast as they are in some areas of California. Major concerns, however, are created when freshwater inflow is reduced as a result of drought conditions. To address this situation, Maryland, Virginia, and the District of Columbia have entered into an allocation agreement. Let me read to you an excerpt from the draft plan: "Maryland is recognized as owning the Potomac River bottom to the low water line on the Virginia side of the river. Although Maryland ceded to the Congress of the United States a district of ten miles square to be used for the seat of the Feder- al Government, the transfer of owner- ship and a later consent given to appropriation of surface waters for supply to the city of Washington did not relinguish Maryland's sov- ereignty over the waters. Instead the Federal entity is considered by Maryland as a lower riparian user. Maryland's authority over the Potomac withdrawals under riparian permit system is not to allow it to deprive the District of Columbia or any other riparian users reasonable use of riv- er waters. Maryland, therefore, is to ensure that an adequate supply of water is available to the competing interests within the framework of 61 PROBLEMS OF FRESHWATER INFLOW PLANNING IN CALIFORNIA Ken Collins Water and Power Resources Service, Sacramento, California I will divide my presentation on policy into three parts. First, I will address the policy of the Water and Power Resources Service in terms of estuarine inflow. Sec- ond, I will speak of the problems of implementing that policy, and third, I will discuss the method of implementation of that policy in California. The policy of the Water and Power Resources Agency is sim- ple. It says that we will mitigate project-caused damages to the bio- logical community. A corollary to that is that water resources pro- jects do have an effect upon the estuarine environment. That is clear. If the policy is so clear, you may ask, then why don't we just implement it and get on about our business? That brings us to the problems associated with imple- mentation of policy. First, there is difficulty in defining the pro- blem. We plan to build a dam on river X and we go to the Fish and Wildlife Service, in accordance with the Coordination Act, and we tell them of out intentions and request to know exactly what the consequen- ces of that action will be. The Fish and Wildlife Service does their best and explains that they know some of the consequences but there are some things they cannot predict. If things were done properly, we wouldn't build the dam because there are many things we don't know. But that is not the way it is. We accept Fish and Wildlife's report and build the dam. Later the Fish and Wildlife Service reports to us that there are now certain factors about the dam that were not known initially but are known now. But, the dam has been built and is function- ing. So the information we didn't have initially is now useless. That brings us to problem number two. The Water and Power Resources Services is governed by law. The Congress of the United States assigns tasks for us to do, and regardless of how I feel morally, regardless of how the Secretary of the Interior feels morally, we must go by the law. As an example I will site the case of the United States vs California. If a state requests us to do a project for them, we can do it as long as it does not violate a Federal law. We may have to go to court in order to convince the state that the Federal Government is not subservient to state law. We all believe that certain things ought to be done, but if the law doesn't provide for it, we can't do it. So the only alternative is to change the law and that is what will have to be done in this case. That brings us to problem two-and-a- half. Lawyers, once they get into the act, forget what the problem is. So consequently, we have been going around and around in the courts on a problem that ought to be solved, but once it is in court we are dealing with the law and not the issue at hand. That brings up problem number three. Shasta Dam, for example, is there. It isn't going anywhere, it is going to be there forever. Now, what we do with Shasta Dam is another 62 issue. At the current time, Shasta Dam's yield and reservoir storage is committed by law to some other use. We have contracts signed; we have water that is being diluted; we have an economy that is based on that water; we have farmers that need water, etc. Now, if the problems that face our estuary are going to be solved, they are not going to be solved with Shasta Dam, because the water from Shasta is already committed. That brings us to problem number four, which is the policy of this agency and the policy of the Secre- tary of the Interior in terms of what ought to be accomplished in solving the problems of the estuaries. However, that policy is subject to interpretation based on the needs at the time, So, we plan to mitigate for all the project damages but, if a problem arises, the Secretary may decide on one course of action. In so doing, his office may look at the very same policy and decide on a whole new direction. That is some- thing that we need to recognize and deal with at staff level, even though we have little to do with the de- cision. I promised to present some solutions to these kinds of dilemmas and I think it was done in the proper manner in the State of California. We have formed a four agency group which consists of the Water and Power Re- sources Service, California Depart- ment of Fish and Game, California Department of Water Resources, and the Fish and Wildlife Service. To- gether, we formulate local policies that address issues we need to deal with. We recognize that there is a general policy for all agencies, but working together we can offer solu- tions to the problems that confront us. In conclusion, I would like to say that nature forever changes for its own reasons. Now, some changes we understand and some we do not, and the approach to the management of nature has been to keep it static. That my friends , is the paradox of our biggest problem. Something I think is quite im- portant for us to recognize and a very, very simple precept is that there are some people around this room who minimize or question the need for freshwater inflow to estu- aries. There are many people who are fully convinced that we need the total amount of water going to these estuaries that we have discussed. The size of an estuary is a very import- ant function of its total ability to put out products, to supply the needs that we are here to talk about. Now, in many estuarine basins, if not most, the effective size of an estuary is directly proportional to the amount of fresh water going in. Here is how that works, if you use, for instance, five to fifteen parts per thousand of salinity as the essential part of the richest segment of the estuarine basin? You can have an average of four acre-feet of this prime estuary for every one-acre-foot of dilution. So, if you put in ten acre-feet of dilution, you have forty acre-feet of estuary and so on, it is directly proportional. I think it is very important to think that it is not only the quality of the estuary that relates to the amount of fresh- water inflow, but its size. 63 Maryland's sovereign authority to regulate the appropriation of Potomac water within its boundaries." I must add that competing interests also in- clude the fish and resources as part of that system. To support this as- surance, Maryland legislative ap- proval is a necessary prerequisite to any withdrawal of water. A study as part of this allocation agreement is underway to determine what water can flow into the lower Potomac. The results of this study will, of course, be taken into consideration in any agreement that is finalized between the signatories. The third form of quantitative problems asso- ciated with urbanization on fresh- water inflow is interbasin transfers. Although this is not a significant problem in Maryland, there are two instances where the potential for interbasin transfer exists and anoth- er one is under consideration. In other areas of the country, this may be of a greater concern. The other problem associated with the inflow of fresh water and man's use of it is the quality of the water flowing into the estaury. There are many problems associated with water quality, but the majority of the problems stem from urbaniza- tion and agriculture. There is a great deal of work going on now to determine what is the exact quantity of agricultural activity that really adds to the problem of water quality as associated with the flowing waters . The primary concern with urban- ization is the sediment loading re- sulting from development. Another aspect is nutrient enrichment. Nutri- ent enrichment resulting from the discharge from municipal sewage treatment plants is an example. It is interesting to note that in a qualitative sense, the withdrawal of water for municipal and industrial uses can also create a quality prob- lem at the other end of the pipe in terms of the discharge from indus- tries by adding pollutants and other toxic substances and nutrient enrich- ment from sewage treatment plants. Additionally, the whole concept of land use change from a vegetated to a paved area increases the surface wa- ter run-off which may in fact lead to increased sediment load. The conse- quences of these kinds of problems can be broken into three basic groups. Natural consequences include the fluctuations in the salt wedge within the estuary, the altered us- ability of the water for aquatic re- sources, the volume of water, the seasonal timing of inflow, and the changes in sediment loading as it relates to the spawning of anadromous fish and resident fish. Another con- sequence related to the social-poli- tical arena are decisions related to the competition between human resources and indigenous resources; these all must be resolved in order to maintain a healthy environment. Lastly, we have jurisdictional con- sequences. These relate to the willingness of an upstream user to pay for the problem he is creating downstream out of his jurisdication. The Maryland coastal zone program goals related to freshwater inflow can be summarized as follows: to maintain or enhance the quality of estuarine water and to ensure an adequate supply of water for the indigenous aquatic resources. The on-going research in the Chesapeake Bay, some of which will be present- ed over the next few days, is de- signed to provide necessary infor- mation to make this goal a reality. 64 MANAGEMENT OF FRESHWATER INFLOW TO ESTUARIES: A LAWYER'S PERSPECTIVE James B. Tripp Environmental Defense Fund, Inc. New York, New York Rivers and their associated floodplains are integrally related to the estuaries into which they discharge. The chemical, physical, and biological conditions of any es- tuary are significantly influenced by those same characteristics of surface and ground freshwater in- flow. The condition of surface and ground water inflows is therefore of critical importance where the maintenance or restoration of the chemical, physical, and biological functioning of an estuary is a rec- ognized objective. Maintenance of freshwater inflow systems as part of an estuarine management program is hampered by three factors-- (1) Federal statutory programs which fail to recognize the interrelationships between riverine and estuarine systems; (2) inadequate scientific knowledge of these rela- tionships; and (3) Federal water re- source development programs that continue to promote massive altera- tion of riverine systems, including floodplain vegetation. Although existing statutory programs can be effective in controlling discharges of some pollutants into surface or ground waters entering estuaries, they are not so effective at con- trolling major alterations of fresh- water inflows, such as hydrologic modifications, alterations in sedi- ment patterns, and loss of riverine wetland floodplain vegetation, which affect estuaries. These legal con- straints are also a reflection of the state of scientific knowledge about riverine-estuarine relation- ships. Increased scientific know- ledge about these relationships will be useful in strengthening the ef- fectiveness of existing programs to combat degradation of freshwater flows to estuaries. MAJOR FEDERAL STATUTES AFFECTING FRESH WATER FLOWS ENTERING ESTUARIES Several Federal statutes ad- dress the subject of freshwater aq- uatic systems and estuaries. Key statutes include the Clean Water Act, the National Environmental Policy Act, the Costal Zone Management Act, as amended by the Coastal Zone Ma- nagement Improvement Act of 1980, and the Fish Conservation Policy Act. However, in significant re- spects these statutes do not and have not been administered effectively to maintain or restore the quality and quantity of freshwater flows to es- tuaries as part of a concerned pro- gram to protect those estuaries. The objective of the Clean Wa- ter Act, 33 U.S.C. S1251(a), is the maintenance and restoration of the chemical, physical, and biological integrity of the Nation's waters. These waters clearly encompass es- tuaries and freshwater flows to those estuaries. The National Environ- mental Policy Act, 42 U.S.C. S4221, The Federal Clean Water Act describes programs affecting ground 65 also provides national environmental policy guidelines in how Federal ac- tions should affect ecosystems. Be- cause many Federal water resource and energy projects typically modify the flows of fresh water to estuaries, NEPA, together with other statutes and regulations which govern plan- ning for such projects, could, in theory, be used to maintain those flows. In addition, recognition in the Fishery Resources Management Act of 1976, 16 U.S.C. S1801, of the importance of fishery habitats for maintenance of fish stocks is implicit Congressional acknowledge- ment of the necessity to protect es- tuaries . In salient respects, however, these acts provide governmental a- gencies at the state or Federal level with only very limited author- ity to maintain, protect or restore the chemical, physical and biolo- gical conditions of surface and ground freshwater flows as they af- fect estuaries. In terms of the Clean Water Act, so much of the de- graded hydrologic and quality con- ditions of freshwater flows to es- tuaries is categorized as non-point source pollution. Second, although ground water flows affect estuaries, Federal and state programs in gen- eral are not effective at regulat- ing withdrawals of ground water which may affect estuaries. Further- more, programs to protect ground water quality through regulation of water, including implicitly ground water flows to estuaries, in Sec- tions 102(a) and 208(b) (2) (K) , 33 U.S. S1252(a) and over ground water has not been clearly re- solved administratively or judic- ially. See, Tripp and Jaffe, "Pre venting Ground Water Pollution: Towards A Coordinated Strategy to Protect Critical Recharge Zones," 3 Harv. Env. L. Rev. 1, 13-20 (1979). discharges to ground water are just now being implemented, and, in gen- eral, they do not consider the ef- fect of polluted ground water on es- tuarine resources. Third, Federal environmental legislation cannot un- do the massive ecological impacts of Federal water projects. Finally, the jurisdictional scope of broad legislation designed to protect coastal resources, such as the Fish Conservation and Manage- ment Act of the Coastal Zone Manage- ment Improvement Act of 1980, is generally too limited to provide a basis for management of freshwater inflows to estuaries. Under the Fish Conservation and Management Act, 16 U.S.C. S1801, although the fish- ery management councils have the authority to make recommendations for inshore estuarine or fresh water ha- bitats which function as nursery or spawning grounds or food sources for Federal and related state pro- grams affecting groundwater quality arises under the Resource Conserva- tion and Recovery Act, U.S.C. S6901- 6907; the Safe Drinking Water Act, 42 U.S.C. S300f to j-9. For a dis- cussion of the potential impact of nitrate contamination in groundwater as it affects estuarine shellfish- eries, see Durand, James B. , Nu- trient and Hydrological Effects of the Pine Barrens on Neighboring Es- tuaries, p. 195, in Forman, R.T.T. , ed. Pine Barrens: Ecosystem and Landscape, 1979, Academic Press, N.Y. 3 Federal laws, regulations and directives applicable to the plan- ning of Federal water resource pro- jects include the 1965 Water Re- sources Planning Act, 42 U.S.C. S1962 and Sections 315, 401, 402, and 404 of the Clean Water Act, 33 U.S.C. S1323, 1341, 1342, and 1344. 66 The enforcement potential of the designated programs is influ- enced by a number of factors, includ- ing administrative interpretation of key provisions of the statutes in question, adminstrative willingness to utilize statutory enforcement pro- visions, judicial interpretations, the advance of scientific knowledge and the effectiveness of beneficiary groups, such as fishermen, shell- fishermen, hunters and recreation- ists, in expressing their political will. MAJOR PROBLEM AREAS WHICH EXISTING REGULATORY PROGRAMS DO NOT EFFECTIVELY ADDRESS Table 1 indicates that some of the pollutant/pollution types and sources affecting the quantity and quality of freshwater inflows to es- tuaries have been identified and are being regulated under existing pro- grams . These include reductions in BOD which affects dissolved oxygen levels, pathogens and, perhaps to a lesser degree, nutrients. In addi- tion, regulatory programs operated under Section 10 of the 1899 Rivers and Harbors Act, 33 U.S.C. S403, and Section 404 of the Clean Water Act, 33 U.S.C. S1344, have reduced non- federal discharges of dredged or fill material into waters of the United States, including wetlands, in particular discharges associated with non-water dependent activities. Together with Executive Orders 11988, 11990, these same programs have, futhermore, to a limited de- gree, beneficially altered patterns of discharge of dredged and fill material associated with Federal wa- ter resource development and other infrastructure projects. On the other hand, as the table indicates, major types and sources of pollution of freshwater inflows which degrade estuaries are subject to ineffective regulation; indeed, on the contrary, major economic incen- tives exist, in the form of Federal subsidies, which promote such pollu- tion. The major problem areas in- clude: A. All toxins from all sources, particularly from indus- trial, agricultural and street/urban runoff sources . B. Changes in the amount and patterns of sediment flow, due to destruction and con- version of riverine wetland vegetation and hydrologic modifications . C. Destruction of freshwater wetland/f loodplain ecosys- tems as a consequence of Federal projects, the sec- ondary impacts of such proj- ects and agricultural clear- ing and drainage. D. Ground water and surface wa- ter diversion, principally for irrigation, municipal and industrial water supply and perhaps, increasingly in the future, energy develop- ment. E. Agriculture as a source of pollution through introduc- tion of toxins and sedi- ment, and clearing and drainage of wetlands. F. Federally sponsored, funded and assisted programs—pri- marily Federal water re- sources development, but also federally assisted in- frastructure programs and energy development. Recent and on-going administra- tive actions and litigation have in- fluenced the scope and direction of some Federal programs which affect 67 marine fish species, Federal autho- rity to protect those habitats generally does not extend inland of the territorial seas. Instead imple- mentation of such recommendations is solely dependent on state action. Fishery management council recom- mendations on fresh water, as well as estuarine habitat protection are therefore apt to be valiant but un- heeded exhortations, with little en- forcement punch. MAJOR CATEGORIES OF FRESH WATER FLOW DEGRADATION AFFECTING ESTUARIES To evaluate the actual or po- tential impact of the Clean Water Act and other statutes which affect freshwater flows entering estuaries, it is appropriate to outline the major categories of degradation of such fresh water flows which can ad- versely affect estuaries. In gen- eral, the broad categories of degra- dation in freshwater flows entering estuaries involve the quantity and quality of those flows. Changes in quantity include modification in total volumes, sea- sonal discharges, rates and timing of freshwater flows. Changes in quality are of two kinds. They in- clude introduction of contaminants into surface or ground freshwaters in a manner, amount or rate such that they enter estuaries. Contam- inants of particular concern in- clude toxic synthetic organic com- pounds, heavy metals and pathogens and major alterations in fluxes of nutrients and sediments. Changes in quality also include reduction in the introduction of beneficial organic material, such as plant de- tritus in dissolved or particulate forms, in fresh waters entering es- tuaries resulting primarily from loss of riverine floodplain wetland vegetation. Thus, clearing, drain- age, filling or dredging of riverine wetland habitat can degrade estu- aries. In addition, since some estuarine fish species spawn in freshwater or depend on food origi- nating in freshwater inflows to es- tuaries, physical destruction of riv- erine habitat can reduce the pro- ductivity of estuaries. The major categories of pollu- tion of surface and ground fresh- water inflows affecting estuaries are summarized in Table 1. This table also summarizes the activities which are the sources of this pollu- tion, classifies these activities as point or non-point sources of pollution in Clean Water Act par- lance and designates these sources as major or minor in terms of their inflows. Table 1 also lists exist- ing Federal statutes which may con- trol these sources and qualitative- ly ranks the enforcement potential of these statutes, as presently ad- ministered, in terms of abating the pollution source so as to protect estuaries. It is recognized that this table represents an over-sim- plification of the sources of es- tuarine degradation through changes in freshwater inflows and types of Federal programs which are designed to abate such pollution or which, on the other hand, contribute to it. See, e.g., Livingston, R.J. , Effects of Forestry Operations on Water Quality and Biota of the Apalachicola Bay System, Final Re- port to Florida Sea Grant College (1978), 400 pp.; Livingston, R.J. , P.F. Sheridan, B.G. McLane, F.G. Lewis, III and G.G. Kobylinski, The Biota of the Apalachicola Bay Sys- tem: Functional Relationships, Florida Department of Natural Res- ources Marine Research Laboratory, Number 6 (1977), pp. 75-100. 68 ■■A CO 0) c OJ > •H 4-1 u II 01 •H o 4-1 HO c O 4-> 4) m e 4-1 c 11 O W £ a. 10 m +j a OJ CO 4-1 ■o 00 d CO o> 4-> a d o 4-1 -H u d o CO ■h a. 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EPA is in the pro- cess of developing effluent limita- tions for industrial discharges of toxins under Section 304 and 307 of the Clean Water Act, 33 U.S.C. SS 1314 and 1317 spurred on by legis- lation, and EPA has, belatedly, proposed and promulgated regulations designed to implement Subtitle C entitled "Hazardous Waste Management" of RCRA. If and when all of these programs are in place, control of industrial and municipal sources of toxic pollutants should be greatly enhanced. In addition, through lit- igation, e.g., NPvDC v^ Callaway, 392 F. Supp. 685 (D.D.C. 1975); followed by Administrative action, including See EDF v^ EPA, 489 F. 2d 1247 (D.C. Cir. 1973); W.A. Butler, "Fed- eral Pesticide Law," Federal Envir- onmental Law, Environmental Law, Environmental Law Institute, 1974, p. 1232. Natural Resources Defense Coun- cil v^ Train, 519 F. 2d 287 (D.C. Cir. 1975); Environmental Defense Fund, v^ Train, Civ. No. 75-0172 (D.D.C.) (settlement agreement, June 7, 1976); Natural Resources Defense Council v. Agee, Civ. No. 75-1267 (D.C.C.) (settlement agree- ment June 7, 1976). See, e.g., EPA Hazardous Waste and Consolidated Permit Regulations, 45 Fed. Reg. 33063-33588 (Monday, May 19, 1980); EPA, Proposed Ground Water Protection Strategy, Office of Drinking Water, (November 1980); Tripp and Jaffe, "Preventing Ground- water Pollution: Towards a Coordi- nated Strategy to Protect Critical Recharge Zones," 3 Harv. Env. L. Rev. (1979). promulgation of regulations under Section 404 by the Corps of Engi- neers, 33 CFR Part 320-329 (now under revision), and more recently, Avoyelles Sportsmen' s League , Inc. , et al., v^ Alexander, et al., 473 F. Supp. 525 (W.D. La. 1979), tena- tive efforts are now underway to con- trol conversion of riverine wetland forests to agricultural or other uses which destroy natural riverine over- flow vegetation and hydrologic cycles. However, these efforts are at best limited in geographic scope, primarily to western Louisiana, such that clearing and dredging of river- ine bottomland hardwood wetland forests continue; scientists are only beginning to understand the impact of agricultural pesticides on downstream riverine and estuarine systems; far too little is known about the impacts of changes of riv- erine hydrology and sedimentation patterns on estuaries; and Federal water resource development projects, now spurred on by coal export and energy development prospects, pro- ceed apace. On the whole, litiga- tion to halt such projects, primari- ly under NEPA, has met with only limited and, typically, only tem- porary success. o For a discussion of legal han- dles to protect riverine overflow forests, see P. A. Parenteau and J.T.B. Tripp, "Federal Regulations: Handles, Effectiveness and Remedies, "Transactions of the Forty-fifth North American Wildlife and Natural Resources Conference (1980), pp. 392-401. 9 For detailed discussion about the magnitude, scope and impact of agriculturally-related toxic pollu- tants, see C.J. Schmitt and P.V. Winger "Factors Controlling the Fate of Pesticides in Rural Watersheds of the Lower Mississippi: River Alluvial (1980), p. 354-375. 74 FEDERAL ECONOMIC PROGRAMS CONTRIBUTE TO ESTUARINE FRESHWATER INFLOW DEGRADATION Aside from industrial and muni- cipal toxin problems, as the above discussion points out, many of the problems contributing to degradation of the quantity and quality of freshwater flows to estuaries are a direct or indirect result of Fed- eral economic programs — direct ap- propriations, tax incentives and economic regulation. Thus while Federal regulatory programs, such as 404 may be working to maintain the quality and quantity of freshwa- ter inflows, Federal water resources development and other economic pro- grams still contribute to the degra- dation of those resources. Federal funds for navigation, irrigation, flood control, water supply and hydroelectric projects directly subsidize modifications of riverine systems in a manner which typically affects estuaries. Fed- eral subsidies in the form of tax incentives, agricultural flood con- trol, SCS engineering assistance, price supports and other U.S. Depart- ment of Agriculture programs to pro- mote the clearing and drainage of coastal flood plain wetland forests and their conversion to cropland or other non-forested uses. A com- bination of Federal irrigation pro- 10^ u a- For a comprehensive discussion of Federal subsidies in support of the conversion of bottomland hard- wood wetlands to agricultural use, see L. Shabman, "Economic Incentives for Bottomland Conversion: The Role of Public Policy and Programs," Transactions of the Forty-Fifth North American Wildlife and Natural Resources Conference (1980), pp. 402- 412. jects, particularly in the arid West and Southwest, and Federal controls on energy prices promote wasteful use of fresh water for agriculture, with contaminant downstream effects on estuaries. Federal infrastructure investments, such as those for highways and sewers, still support development in riverine flood plains. Finally, Federal economic regulations of railroads increases the cost of rail transportation relative to barge transportation and thus increases the "demand" for Federal navigation projects, although the Staggers Rail Reform Act of 1980 (P.L. 96448) over time should begin to rectify this inequity. IDENTIFICATION OF ALTERNATIVE STRATEGIES FOR ACHIEVING ECONOMIC OBJECTIVES WHILE MAINTAINING FRESHWATER INFLOWS TO ESTUARIES Because Federal economic pro- grams and policies play such a cru- cial role in activities which alter adversely freshwater flows to estu- aries, reformation of those policies is the single most important factor in any national strategy to protect estuarine resources through proper management of the quality and quantity of freshwater inflows. Judicial strengthening of private and public nuisance concepts to provide for strict liability for private polluters whose waste streams to ground or surface waters degrade estuaries is another important factor in such a strategy. Continued degradation of the Na- tion's renewable resource base which supports its fisheries and shell- fisheries should be deemed unaccept- able in terms of national and global trends for such resources If this 11 See The Global 2000 Report to 75 objective is to be attained, primary reliance on Federal or state regula- tory programs is only a partial answer. The larger quest must be the search for alternative pathways to achieve economic objectives which avoid disruption of surface and groundwater systems in a manner which will maintain estuarine resources. In many cases, because of the perverse impact of Federal economic policies, alternative conservation- oriented water supply, energy and transporta- tion investments not only avoid such disruptions but enjoy substantial economic benefits vis-a-vis disrupt- ive programs. In addition, insofar as conversion of riverine forests to agricultural use is expanded, other Federal policies which promote con- version of farmland to other non- agricultural uses should be al- tered. Finally, economic incen- tives to support development of in- novative technologies which will pre- serve riverine and estuarine renew- able resources must be identified and adopted. Federal natural resource agencies, such as the Department of the Interior, the National Marine Fisheries Service and Environmental Protection Agency should participate in the effort to identify and imple- ment such alternatives. DISCUSSION QUESTION: Gil Redonski, Sport Fishing Institute. Mr. Tripp, I'd like to ask you what the status of the Rural Clean Water Act is? You mentioned non-point source pollu- tion from agriculture, and that the Rural Clean Water Act would deal with the problem of non-structural pollution abatement. One of the problems is that, as I understand it, it has not been funded. Can you give us any insight on the fu- ture of the Rural Clean Water Act? REPLY: Only to a very limited degree. I'm not terribly familiar with the program, but I think you mentioned one of the problems which is funding. If you don't have funding, and unless you have a con- stituency that is interested in doing something about the problem in certain basins, the problems of erosion become virtually so severe that you might want to develop a constituency among the farmers to do something. The other major pro- blem is that all these U.S. Depart- ment of Agriculture programs are voluntary. There is no conservation service, even where they provide subsidies to farmers to enter the President, Entering the Twenty- First Century, Volume One, Council on Environmental Quality (1980). For economic analysis of al- ternative investments, see, e.g., Z. Willey et al., An Alternative to the Allen-Warner Valley Energy Sys- tem: A Technical and Economic Ana- lysis. EDF (July 1980); J.R. Morris and C.V. Jones, Water for Denver: An Analysis of Alternatives, EDF (1980); affidavits of Dr. Granville Sewall and Dr. Clifford Russell in support of motion for an injunction, EDF et al. v. Johnson, Civil Action No. 79-2228 (S.D.N.Y. 1979). 13 The rate of and courses of conversion of the Nation's agricul- tural land base to non-agricultural uses are presently under study by the National Agricultural Lands Study, CEQ and the U.S. Department 76 enforceable contracts with the farm- ers about how they should change their practices to reduce sediment discharges, pesticide discharges or clearing. It is a voluntary pro- gram, and by and large, a lot of them have a very short discount pe- riod. Of course, a lot of farmers are tenant farmers and are on year to year leases. They are not in- terested in spending any money to try and take care of these problems. But in a lot of cases, you are talking about investments that may not have a pay-off for ten years, and there just aren't a lot of farmers that want to wait that long, and the agencies aren't making them do it. QUESTION: Is the lack of tech- nical data slowing down some of the litigative initiatives that you know about? REPLY: I think that is a pro- blem. There is a tremendous amount of technical data. I can think of two examples: One is the effect of changes in the use of riverine flood plains on riverine hydrology and therefore, estuarine hydrology. You are talking about using some really sophisticated state-of-the- art models to try and predict what is going on and it is difficult to do. It becomes particularly diffi- cult when one is dealing with a large number of cumulative effects. I know that the Corps, in the case of the Cache River Basin said that project would have an insignificant effect on the levels of water on the White River. The Yazoo River Basin proposed pump project raised a of Agriculture. The Study is expect- ed to make recommendations on changes in Federal program and policies which support such conversion. question and comments on some draft EIS, as to how that would affect flood stages in the Mississippi. The response was that it would raise flood stages in the Mississippi by one foot at Vicksburg which struck me as being quite a bit, but they said downstream it would just disappear. I find that hard to believe, but it is very hard to find technical data to show response to that. Another example would be changes in inputs of organic nutrients resulting from the destruction of wetlands. It is just literally impossible to get any information on that because reduc- tions on the amount of organic nutrients which are of value to the river and the estuary are not re- flected in the water quality stand- ards. Water quality standards deal with BOD, or toxics. Introduction of contaminants or removal of something is a legal problem but also it is a serious technical problem. I think, when you talk about hydrology, you get into the driving forces behind the systems. That is a new and different world, the process side of the ecosystem rather than the structual side. I know a few years back I was working on an EIS for a highway crossing some wetlands on Long Island. In the mitigation recommendations, we suggested they fix up a few wetlands, but we also suggested that they open up some of the culverts and improve the water flow a little bit so as to improve the energy flux and other processes in the wetlands. That got down to Washington and it got a lot of interest from the folks in the Department of Transport- ation environmental review session because they thought it was really innovative and different to be trying to mitigate by adjusting the processes rather than just the struc- ture of the system. I think that gets us into a very complicated world 77 but I think it is one we are going to have to step into fairly soon, because you have these driving forces working on your ecosystem and what we are really driving at a lot of times is controlling them. Yet we are so used to buying pieces of wetland or building islands for mitigation, that we often loose track of the fact that what we are really after is trying to conserve the process base. Most of the agencies that may be concerned about this whole pro- blem tend not to appoint hydrolo- gists, or very few of them. The agencies that are interested in engineering manipulation of the river and estuaries, and there are a large number of them, have hydrolo- gists who don't have training in ecology. This doesn't seem to enter into their thinking. QUESTION: John Clark: I'd like to ask just one more question here before we move on to the next speaker. I would like to ask Jim what benefit he would see in the work he does from far more exten- sive quantitative, monetary evalu- ation of the resources that are de- pendent on estuaries. Is that going to help or hurt your case? REPLY: Tripp. My answer is that economic quantitative analysis of the value of the Nation's natural resource base should be pursued with vigor. I think you have to be acute- ly aware of the limitations of these studies. You also have to remember that the level of sophistication of economic analyses done to justi- fy water resource projects is also in an infantile state. Most of the time, we can take any Corps project, I won't speak for the Water and Power Resources Agency because I haven't done any work with it, and easily find highly qualified econo- mists who will go out and say it is an absurd methodology that the Corps uses and very overstated. A large economic analysis is a tool and nothing but a tool, carried out by various groups to further a po- litical fight. Even recognzing the severe limitations of quantitative economic analyses, I think that they should be carried on. I got a paper just the other day from an economist on the value of wetlands. His ar- gument was that the degree of so- phistication of analyzing the value of wetlands from the quantitative point of view is still in a very primitive stage, and that the major economic argument in support of pre- serving wetlands is uncertain, i.e., the risks that you take by destroying the resource. CLARK: I have some doubts whether the answer you get every time is all that helpful to you because I've seen some analyses of the values of components of estua- ries expressed in dollar terms funded with state-of-the-art analy- sis. In fact, it seemed like a rather trivial price tag per acre of wetland or per acre of estuary, and I'm not so sure that in every case the price tag we come up with is going to give us the answer we want. 78 WATER MANAGEMENT ON THE COLUMBIA RIVER David Kent Columbia River Basin Commission, Portland, Oregon We have heard comments about needing long term studies of estua- ries twenty-five years from now. How do we deal with Federal water resource projects when we lack adequate information from which to base decisions. Jim addressed these issues more from a national perspective. I would like to speak about the regional problems on the Columbia River. The Columbia River with its estuary and its tributaries is the dominant Pacific Northwest water re- sources system. Originating at Columbia Lake in the Canadian Rock- ies, the Columbia flows about 1200 miles to the Pacific Ocean. Dis- charges on an annual average are about a quarter of a million cubic feet per second of water at its mouth. The drainage area is about 260,000 square miles or about five times the drainage area of the Chesa- peake system. This 260,000 square miles includes about 85 percent of the total area of the Pacific North- west. The Columbia system, includ- ing its largest tributary the Snake River, flows through seven states as well as Canada. The Columbia River estuary, which for administrative purposes is defined as the last 46 miles of the river, is the ninth largest in the United States. Here fresh and salt waters mix in a rich and fragile environment. The re- gion's water problems stem largely from the competing uses to which the river is put. Residents of the Pacific Northwest count on the river to supply sufficient hydroelectric power and support ever-increasing agricultural production with irri- gation development. We count on it to provide transportation for com- merce while maintaining fishery re- sources and to provide recreation opportunities for everyone. What we are asking is that the Columbia be all things to all people all the time. Unfortunately, what we are asking is not possible all of the time. To help understand the puzzle of these competing uses, I am going to briefly describe just three of the major areas for concern. Pre- sently, the Columbia River with its storage system is used to generate about 80 percent of the electrical energy for the northwest. To supply this energy, the river's water must pass through turbines in one or more of the 60 mainstream or tributary generating plants. These turbines threaten the survival of juvenile fish moving downstream, while the dams present an obstacle to adult fish migrating upstream. As the human population of the region increases, so too will the demand for energy. Because most of the best hydroelectric sites al- ready have been dammed, it will be necessary to build more thermal or nuclear-generating plants which di- vert water for cooling purposes and much of this water then is lost. Approximately eight million acres of land in the Pacific Northwest are now being irrigated by water divert- ed from the Columbia River system. This accounts for more than 90 per- cent of the region's total water 79 diversion and comsumptive use. It is expected that within 20 years, there will be a 25 to 40 percent increase in irrigated land within this region. Already competition between the hy- droelectric generation and irrigation is intense. The amount of hydroelec- tricity generated depends on the vol- ume of water passed through a given generating facility. Reduction in volume means less potential for electric generation, not only at the first structure but at each of the dams that are downstream. In other words, the loss is multiplied by the number of dams downstream of the di- version site. Furthermore, electric- ity is used to pump the water inland for irrigation, thus placing addi- tional demands on existing generating capacity. Meanwhile, hydropower and irrigation demands are putting pres- sure on a third use of the Columbia's waters, the fish runs. For maintaining fish runs, water must be available in adequate quan- tity and quality for the fish to survive and at the proper time to provide for both the upstream and downstream passage of the juvenile fish, the amount of water available to generate electricity is reduced and you can see that all of these are interrelated and tend to compound each other. Power generation, irri- gated agriculture, anadromous fish runs are all vital to the Pacific Northwest region but, in varying degrees, are at odds with each other. It is clearly evident that the de- velopment of any one of these uses to their full potential can only be at the expense of others. Already you can see how difficult these con- flicts are to settle, and I have not even mentioned instream flow needs for navigation, recreation, water quality protection, and preservation of the natural environment. And there are others. But, competing uses are only half the problem. The other side of the puzzle is that of jurisdiction. The Columbia River system waters within the United States are con- trolled by seven states, at least nine Federal agencies, several state organizations, and a multitude of public entities, local jurisdictions, and under permit, private individu- als. Each of these entities has only limited authority over the responsi- bility for the management of the Columbia's water. Its flow is stored or diverted and consumed as a result of numerous decisions that are usual- ly uncoordinated and made with little regard for other demands. The riv- er's management is influenced by cit- izens' groups, municipalities, users from other states, local Indian tribes, and a host of these entities involved has overall or even broad responsibility for the uses of the Columbia River water. All too often, the result is a variety of piecemeal and conflicting policies that fall short of everyone's desire for wise management of the river. So, having explained that there are competing uses and numerous jurisdictions in- volved in water resource decisions before the water reaches the estuary, we can now address the question of how choices are made, or to put it another way, who gets what and why and how these impact the Columbia River estuary. It would be naive to suggest the water allocation decisions are based on what is best for all. Money influences decisions and managing the Columbia River is no different. Those uses which are economically most profitable, are the ones which receive the greatest consideration by the decisionmakers. In the case of the Columbia, hydropower is the most important. Irrigation is next, followed by transportation, and a 80 distant fourth or even further, would come fisheries and conservation. Let's examine this decision hierarchy in terms of its economics. What are the values of the various uses? I had some trouble digging up money figures for some of these, so I am going to have to improvise in some of the cases. First, let's look at electricity. As I mentioned earlier, hydropower presently provides about 80 percent of the region's energy. Most of the remaining 20 percent is generated at thermal electric or nuclear plants. As a power resource, the Columbia River system has more hydropower potential than any other system in America; about one-third of the national total. There are now over 24^ million kilowatts of installed capacity and another b\ million under construction, for a total of 30 million kilowatts. Ex- cept for some small projects, that is probably close to the river's short term potential. That hydro- power energy represents about 50 percent of the energy generated in the Pacific Northwest. I do not think I need to translate that into dollars and cents. It is enough to say that the hydroelectricity gen- erated on the Columbia River is big business. There are not many north- west residents who would want to see it otherwise since they are all well aware that they pay considerably less than the rest of the country for their electric energy. The mag- nitude of the dollar decisions in- volved warp the conservation and fisheries concerns of those who depend on the estuary and its re- sources. Let me add that it has been estimated that in the next two decades, the population of the Pacific Northwest region will jump from its present seven million peo- ple to more than eleven million. The demand for energy can be expect- ed to increase. Along side the increased de- mand for hydropower will be the in- creased demand for water to irri- gate farmlands, to produce more food and fiber for domestic use and export. The Corps of Engineers has estimated that our needs in the northwest for irrigated land may increase by four million acres over the next fifty years. New irriga- tion development has been increas- ing in recent years at a rate of about 80,000 acres per year. The projected increase of four million acres will deplete the Columbia River by nearly nine million acre- feet of water. That translates to more than 966 megawatts of poten- tial power and more than 1.8 billion dollars in economic revenue annual- ly. My rough calculations indicate that in 1972, the value of the seven highest-ranked crops in the Pacific Northwest was about 1.5 billion dollars annually. Taking the per- centage of those crops that are ir- rigated, I found their worth to be 930 million dollars annually. Had I included wheat, of which only five percent is irrigated, I would have found a total worth of over a bil- lion dollars. In other words, ex- cept for wheat, almost 90 percent of the income in the region from the seven more prolific crops is a direct result of irrigation. Per- haps, I need to clarify something for those of you who are not fami- liar with the Pacific Northwest. Except for the area west of the Cascade Range, most of the region has a fairly dry climate. Of the whole, only a small percentage is the lush green of the Willamette Valley or the rain forest of North- west Washington. Most irrigation in the north- west is powered by electricity. There are some who irrigate by grav- ity feed systems, but the majority 81 use sprinkler systems or other sys- tems that require electricity to pump the water. So not only is ir- rigation reducing the potential for energy generation by withdrawing water, it is also a tremendous con- sumer of electricity. This energy, that is lost, plus the necessary power to run the irrigation pumps, when valued at the replacement costs of the additional generation facili- ties that must be developed, results in a continuous and increasing ex- pense to power consumers in the northwest as irrigation grows. As I said earlier, the next use of the river, in terms of economics, would be transportation. Recent dollar figures are not available. Tonnages shipped are used as a mea- sure of water-borne commerce signi- ficance. In 1975, nearly 65 million tons of commerce were moved through the Columbia River system. This total comprised approximately 17 million tons of foreign imports and exports and 44 million tons of in- ternal and local movement. The system provides a principal water- borne outlet for a large portion of Oregon, Washington, and Idaho crops. Export grains and shipment of forest products are among the principal out- bound items of commerce. Much of the petroleum products used in the area are brought into the Columbia by deep draft tankers and then are distributed by barge and truck into the interior. Fortunately, naviga- tion on the river does not conflict with many other uses. Dams are built with locks, and water volumes for their operation are usually less than is needed for the fish- eries. There was no question as to whether the money should be spent to dredge the Columbia River chan- nel after the May 18 eruption of Mt. St. Helens. Millions of dollars to the region are lost every day that the navigation channel was closed. By the way, I believe the recent cost figure for that total dredging project was around 53 million dollars . In a distant fourth come the fisheries and the estuary. Cur- rently, the value of the fisheries to the region is about 20 million dollars. Obviously, that is pretty small when compared to the value of hydropower, irrigation, or trans- portation. It is this disparity in value that is the base of the issue of water use priorities. Fish re- quire adequate flows and assistance to negotiate dams and other water intakes. This water represents po- tential economic losses to other uses and the monetary returns from the fish do not amount to much re- gionally. Here is a quote from a big energy official in the north- west that I think captures the es- sence of the issue: "If the amount of water that must be spilled is as large as some fish interests request, the loss of energy could be substan- tial and possibly disproportionate to the value of the additional adult salmon that will return to the Col- umbia as a result." What he is say- ing, I gather, is that money is the scale on which we should weigh the worth of protecting the fisheries. I think that is a point that could well be argued. Having determined that economic reasoning seems to be carrying the greatest weight in de- cision priorities between the riv- er's competing uses, I would sug- gest that social concerns would follow, and finally, environmental protection. Obviously all of the current uses of the Columbia River are of value to the region. I am in no way saying that any one of them should be precluded. But, I am sounding a warning that must not be ignored. On the Columbia River, the 82 water volume is rapidly approaching, if not already passed, the point of over allocation, and a viable man- agement structure has not yet sur- faced. The implications of over allocation to the estuary and the river's natural systems is profound. Only now through the Columbia River Estuary Data Development Program and other research programs on the Columbia is the first piece of that puzzle called the Columbia River being studied systematically. Let us hope that the solution of this puzzle is found before it is too late for us to control changes in the way the Columbia River is man- aged. be taken care of by conservation rather than production of more power: REPLY; KENT; I haven't seen any figures on how much of that in- crease of energy consumption could be met by conservation. Some of the figures that have been tossed around have been as high as 50 percent. But as far as the northwest is con- cerned, I don't know. It is a fact, for what it is worth, that the northwest region has historically had very cheap electrical energy. It may very well be that shifting to alternative sources of energy could result in meeting most of these demands . DISCUSSION QUESTION: I would like to ask whether you think that, with an in- crease from seven to eleven million people, how much of the apparent increase in energy supply needs can Along the same lines, I read recently in Business Week that the per capita consumption of electrici- ty in the northwest is twice the level of consumption of the rest of the country and that would certainly suggest to me that the 50 percent figure is not far off. 83 FRESHWATER INFLOW AND WATER MANAGEMENT IN CALIFORNIA Gerald Johns California State Water Resources Control Board Sacramento, California I would like to present a brief example of how California has tried to handle its water supply problems and how it tried to merge techni- cal, legal information, legal prin- ciples and public interest in order to develop enforceable water quality standards to protect the San Fran- cisco Bay-Delta system. What this requires is adequate inflow to the estuary in order to protect that system. The delta represents about half of the fishery in California which either migrates through or lives in the delta, specifically, or in the bay area. In order to give you an idea of what we are talk- ing about here, I have a few slides which show California and some of its water supply projects. Most of California's water supply falls in the northern part of California a- bove the delta. However, about two- thirds of its population is below the delta and, in addition, water supplies to the San Joaquin Valley are provided not only from the San Joaquin River but also from the Sa- cramento River. An engineer once said that the problems in Califor- nia are not water supply problems. There is plenty of water in Califor- nia. What exists is a water distri- bution problem, because all the water is in the north and all the uses are in the south. So, one of the issues then is that the delta sits basic- ally at the hub or the center of this water distribution problem. When water supply and water distri- bution questions are raised, you always have the corollary issue raised with protection of in-basin users and the instream uses. We have the same problem in California as in the other basins in the Nation where their interests are all com- peting for the same block of water. We have in-basin users not only within the San Joaquin Valley and the upper Sacramento Valley that use the water there for agriculture and industrial supplies, but there are users in the delta that need water for salinity control, flow for fish protection and also a large exporting interest that takes water out of the delta, down the Califor- nia aqueduct into southern Califor- nia, and through the Delta-Mendota Canal into the San Joaquin River. Each of these interests, of course, questions the legimate needs of each in terms of whether or not their needs are legitimate. In order to adopt enforceable standards, you basically have to convince each other--all these competing interests --that each of their needs are legi- timate. In other words, goals and priorities for water development and water distribution must be estab- lished. Also you need to be able to document technically how you are going to achieve these goals. When California recently adopted a Water Rights Decision in 1978 and a water control plan to address the issues of protection for the delta, some- body needs to do the balancing. We have competing interests, and somebody has to step in and do an independent balancing act. That is basically what the agency that I 84 work for does. The State Water Re- sources Control Board is the water- right agency in California. People that divert water in California have to apply to our agency for an appropriate permit and we then set terms and conditions for those per- mits. In the delta they take the form of water quality standards and export limitations. We are also in charge of water quality laws in California. We im- plement not only California water quality laws, but also the Federal Clean Water Act. The board has five- members. Each member is appointed by the governor to a four-year term. In water right proceedings, which are quasi- judicial in nature, you have cross examination of witnesses and the board acts more or less as the judge. In Decision 1485, we had 32 very arduous days of testimony pre- sented where we had no fewer than 35 participating groups each cross ex- amining each other. It took over two years to accomplish. It is not the type of project you want to do very often, to say the least. In the delta, there are a number of agri- cultural uses on a number of is- lands that are created by the water entering through the delta. There are municipal and industrial uses within the delta. Pittsburg and Antioch also divert water for use within the delta and outside of the delta. There are interests that di- vert water from the center portion of the delta, interests that must manage the productive Suisun Marsh area, interests that manage delta fisheries, and that's all. But that is enough, because we are all looking for the same types of things. So when we hold hearings, we basic- ally invite parties to come together, present the information, and then we try to sort out the facts. The information is presented to us by U.S. Water and Power Resources Ser- vice, the U.S. Fish and Wildlife Service, the California Department of Fish and Game and the California Department of Water Resources in the four-agency ecological program. The program has been collecting data in the estuaries since 1959 and probab- ly has the best continuing record of fishery related impacts that exist. The history of water develop- ment in California is too great to go into here. I think it will suf- fice to say that the problems have been around since the early 1900' s. Water projects were built in 1945 and later supplied water in Califor- nia for inter-basin transfer. It has been a boiling controversy ever since. The things that I might men- tion rather quickly are the fact that we have some laws on the books that help guide how we should devel- op standards. The Delta Protection Act was adopted in the 1950 's and was labeled at the time as being the great law that would tell everybody exactly how much the delta should get or what it is entitled to but not how to provide the water. It becomes an administrative problem to try to provide the water. In 1976, we started our delta hearings and we were basically work- ing from a very set stage. We had already issued water right permits for the Central Valley Project and State Water Project. In these per- mits , we have a rather nice clause that the Federal Government is not too crazy about. Basically this is the reserve jurisdication. What we do is we recognize at the outset that we do not know everything there is to know. We adopt standards bas- ed on the imperfect knowledge at all times. We, however, reserve the jurisdiction to change those stan- dards later on. This does nothing 85 but create havoc with water-develop- ment engineers because they calculate their yields based on what the stan- dards are currently, and then the standards change in 10 to 15 years. So they are continually trying to figure out what is going to be the next set of standards. This is a thorny issue between the Federal Gov- ernment and the State. We have also adopted water quality control plans for the Central Valley and the delta under our Clean Water Act authori- ties. Here we had some legal guid- ance, but we did not have a clear set of principles that should be follow- ed. We also were in the process of having or experiencing a very exten- sive drought in California and everybody was clamoring for the same block of water. It didn't take very long before we had what I called an "ah ha" experience. You sit down and you go "ah ha," that's what the problem is. Our first major discovery was that if there was an easy political answer to the problems of water supply in California they would have thought of it 50 years ago. There was simply no easy way out of the problem. First, you are not going to please everybody, so what- ever decision you come up with it is going to have to be legally and technically defensible because you are likely to be sued no matter what you do. First, take the prob- lem apart, then divide it into bite size pieces and then start chewing away on the pieces. The other thing we had to do was to re- cognize that we were not going to solve all the problems all at once. You have concerns with basin devel- opment and export development and we had to pick out those that were most important and try to resolve them. Who should protect the delta was the first issue we were faced with? Was it the in-basin users who are diverting water within the basin or the exporters? There are many types of exporters in Califor- nia. In addition, you have the rather large State Water Project and the Central Valley Project which are delivering water to the San Joaquin Valley in Southern Califor- nia. The water law in California states that exporters are the last to be considered in the system re- gardless of the kind of priority or the way the development projects were built. The State Water Project and the Central Valley Project were the last of the exporters. I will give you a brief example of how we applied this concept in California. First of all, we had to develop a rational policy of what protection should be afforded fisheries. In this case, I will give an example of striped bass survival. Luckily, we had a rather large amount of data on striped bass. The informa- tion indicated that flow and diver- sion rates out of the delta affected striped bass survival, particularly young striped bass. We determined that had the project not been built, there would have been a stiped bass index of around 71. A striped bass index is a relative number that in- dicates the relative abundance of young fish in the estuary. With those same relationships, we deter- mined that the existing plans that we had at the time would have pro- vided an index of around 63. We then went about developing standards that would try to achieve this in- dex 63 goal at the mitigation level in the estuary. In the standards that we developed, we require much greater protection in wet years than would have been experienced historically and we tried to allow for lesser protection in critical dry years. Yet, we still try to get the overall protection needed Mi, to attain this mitigation level. In addition, we have some long-term goals of trying to reach what is called "recent historical levels." These provide a much higher pro- tection and include some major en- hancement. We feel this can only be achieved with the removal of the exports out of the southern portion of the delta where they are current- ly damaging the estuary. There are current proposals to do that. In summary, I would like to emphasize that we all know that estuaries have very difficult prob- lems that are hard to solve. They must be solved by taking the prob- lems apart, developing goals on which to base standards, and having the technical information available to back up those goals. The pro- gram must then be developed to attain a suitable solution. The other key ingredient is to have an agency with the authority that can implement the standards. The agency must actually implement the program. Decisionmakers need the scientific information that we will be talking about here, but it is fairly worth- less if we do not have the guidance in terms of what the public interest is. In closing, I would like to say that in the developing centers of California we realized at the outset that we could not make every- body happy. We have 14 lawsuits being sued by in-basin users, by exporters, and by people within the delta. We actually welcome these suits because we are developing new ground here; and we hope that these lawsuits will help resolve the long standing legal principles and questions of authority that have plagued us in the past. We were not successful in making every- body happy, however, we were suc- cessful in our secondary goal, and that was to make everybody equally unhappy. 87 FRESHWATER INFLOW PLANNING IN TEXAS Herbert Grubb Texas Department of Water Resources, Austin, Texas The Texas bays and estuaries are valuable public resources. They provide habitat for fish, birds, and other living organisms; they contain important archaeolo- gical and historic sites; and they are scenic and recreational assets. In addition, the bays and estuaries attract and support business and human uses; for example they have been modified to provide shipping lanes for Texas' marine commerce, and are used for recreation by thousands of visitors annually. Texas has shoreline with most of which row strips of lands . Behind almost 400 miles of the Gulf of Mexico, is bordered by nar- sand or barrier is- the islands are lo- cated seven major estuarine systems and several smaller estuarine areas. They are fed by eleven major rivers, ten with headwaters originating within the State. These range from the high precipitation drainage basins of the northeast Texas coast to the arid drainage basins of the southwest Texas coast. Associated with these drainage basins are ap- proximately 2,100 square miles of coastal environments, including more than 1.5 million acres of open- water bay surface area and approx- imately 1.1 million acres of adja- cent marshlands and tidal flats. Texas' estuaries are a source of significant quantities of inputs to the State's economy in the form of navigational networks, a natural source of treatment for nutritive wastes, mineral and energy deposits, fisheries, and recreation areas. For example, the total Texas harvest- of estuarine-dependent seafoods by commercial and sport fishermen aver- aged about 110 million pounds per year during the 5-year interval from 1972 to 1976 (i.e., ^20 million lbs/year of fish and ^ 90 million lbs/year of shellfish). Shipping lanes traverse the entire Texas coastal area, linking Texas' 33 ports, including the Brownsville Corpus Christi-Houston-Galveston- Beaumont-Port Arthur energy refining and petrochemical production and shipping complexes to world and national markets. Significant proportions of the crude oil and natural gas produced in Texas and sold into national markets are produced in the Texas coastal area and off-shore of the coast. The Texas coastal area also supports major agricultural enterprises rang- ing from tropical fruits and vege- tables to food grains, livestock, and timber. The Texas coastal area has five Standard Metropolitan Statisti- cal Areas (SMSA) in which about 3.8 million people or nearly 30 percent of the population of Texas live and work in a highly specialized, technologically advanced industrial society. These SMSAs are linked to the Texas interior through trans- portation and trade and are located near the mouths of rivers which are used throughout their extent as sources of fresh water for municipal, industrial, agricultural, mining, hy- droelectric power, navigation, rec- reation, and other purposes, includ- ing disposal of treated waste ef- fluent. All of these factors must be 88 taken into account, as the topic of freshwater inflow for bays and estuaries is considered. Since practically all (97.5%) of the coastal fishery species are con- sidered estuarine-dependent , and since the esturies themselves are dependent upon freshwater inflows for nutrients, sediments, and a viable salinity gradient, the oc- currence of sufficient freshwater inflow is necessary to maintain the productivity of Texas estuaries. Enactment of Senate Bill 1139 by the 65th Texas Legislature (1977) resulted in the consolidation of the three former Texas water agencies; the Texas Water Development Board (TWDB), the Texas Water Quality Board (TWQB) , and the Texas Water Rights Commission (TWRC) . In so doing, Senate Bill 1139 created a new Texas Department of Water Re- sources (TDWR) with a newly-created Texas Water Commission (TWC) as its judicial arm, and the existing six- member gubernatorially-appointed and Senate confirmed Water Development Board incorporated as TDWR's policy branch. All executive and adminis- trative functions of TDWR are the responsibility of the executive director, who is employed by the board. The executive director also assumes the mandates for development of and periodic updating and amend- ing, as necessary, a Texas Water Plan and completion of comprehensive studies to determine freshwater in- flow needs of Texas bays and estu- aries. The TDWR is charged with the responsibility of ensuring that all present and future water needs of the State are met through an orderly water development and management program. The substantive law of Texas with regard to water development, water quality, and water rights was not altered by consolidation of the water agencies. However, under TDWR an increasingly effective co- ordination of water quantity and water quality programs is being realized since problems and solu- tions associated with both aspects of water resources management are now within the sphere of a single water resources agency. State law directs the execu- tive director to "prepare, develop, and formulate a comprehensive state water plan," wherein the director must "also give consideration in the plan to the effect of upstream development on the bays, estuaries, and arms of the Gulf of Mexico and to the effect of the plan on navi- gation" (Section 16.051, Texas Water Code) . Codified from the Texas Water Development Board Act of 1957, these statute provisions were the first legislative direct- ives to focus Texas water resources planning on the real problems asso- ciated with alteration and/or de- pletion of riverine flows to the estuaries . As a result of the Legisla- ture's 1957 planning mandate, a Texas Water Plan was prepared, pub- lished, and released in 1968. Fol- lowing an affirmative finding by the Texas Water Rights Commission that the plan gave adequate considera- tion to the protection of existing water rights, the plan was formally adopted by the Texas Water Develop- ment Board in 1969. In addition to describing the State's water re- sources, projected requirements, and a proposed plan of development for each of the river basins in the State, the plan also provided for the delivery of up to 2.5 million acre-feet per year of supplemental freshwater inflow to Texas estuaries between Galveston and Corpus Christi through controlled releases from 89 the coastal component of the proposed Texas Water System. Conceptually, the system was to conserve and con- trol water from basins of surplus to areas of need throughout the State. Although the Texas Water Plan tenta- tively provided for supplemental freshwater inflow on an annual basis, it was clearly recognized that the quantity specified was a preliminary estimate based on the best available information at the time. Further- more, the optimum seasonal and spatial distribution of these pro- posed supplemental inflows could not be determined at that time because of insufficient ecological knowledge concerning these large-scale eco- systems and their interlocking com- ponents . The acute need for comprehensive estuarine data bases and reliable set of technical criteria for defining the responses of the ecosystems to variable freshwater inflow regimes was obvious in order to analytically solve the problem. Although several limited programs were underway, they were largely independent of one another and none of the programs were truly comprehensive. In fact, in some Texas estuaries virtually no data had been collected. Therefore, the Texas Water Development Board, in cooperation with the U.S. Geological Survey, initiated a reconnaissance- level study program during 1967. This Bays and Estuaries Program was progressively expanded through the following years, particularly after the additional legislative recogni- tion and funding provided through enactment of Senate Bill 137 by the 64th Texas Legislature in 1975. Un- der the mandate of this State law, the executive director of the depart- ment must "carry out comprehensive studies of the effects of freshwater inflows upon the bays and estuaries of Texas, which studies shall include the development of methods of pro- viding and maintaining the ecological environment thereof suitable to their living marine resources" (Section 16.058, Texas Water Code). Senate Bill 137 also amended State public policy, declaring "it is the public policy of the state to provide for the conservation and development of the state's natural resources, including ...the maintenance of a proper ecological environment of the bays and estuaries of Texas and the health of related living marine re- sources" (Section 1.003, Texas Water Code). Further, the law directs "in its consideration of an application for a permit to store, take, or divert water, the [Texas Water] commission shall assess the effects, if any, of the issuance of the permit on the bays and estuaries of Texas" (Section 11.147, Texas Water Code). The principal problems that have affected this assessment stem from the previously incomplete analysis of the freshwater inflow needs of Texas estuaries, and from the fact that the adjudication of surface water rights for each Texas river basin is a com- plex and extremely lengthy legal procedure. Required by the Texas Water Rights Adjudication Act of 1967 (Section 11.301, Texas Water Code), the adjudication process was estab- lished to assure each surface water claimant all of the due process and constitutional protection to which each is entitled, and to provide for the "administration of water rights to the end that the surface water resources of the state may be put to their greatest beneficial use" (Sec- tion 11.302, Texas Water Code). As of August 31, 1980 the adjudication program was about 72 percent complete (5,989 parties adjudicated of a total 8,336 parties statewide). Although the process has been accelerated in recent years, it may still be several years before adjudication of claims in all Texas river basins is 90 completed. Currently, several final judgments have been rendered by ap- propriate State district courts and certificates of adjudication have been issued by the Texas Water Com- mission for portions of the Rio Grande, Colorado, and San Antonio river basins. In considering each application for a permit for the appropriation of State water, the Texas Water Com- mission is directed to "assess the effects, if any, of the issuance of such permit upon the bays and estu- aries of Texas" (Texas Water Code, Section 11.147, as amended). Thus, a water rights permit may be denied for any valid reason, including detri- mental effects on the bays and estuaries. Similarly, in developing the State water plan, the TDWR is directed to "give consideration in the plan to the effect of upstream development on the bays, estuaries, and arms of the Gulf of Mexico..." (Texas Water Code, Section 16.051, as amended) . The commission must make decisions on each application for a permit, which could have a sig- nificant effect upon an estuarine system, using the best available information on existing unappro- priated water and relying upon recommendations or information pro- vided by the executive director, other State agencies such as the Texas Parks and Wildlife Department, as well as any testimony which may be presented at the public hearing on each such application. State law (Section 11.024, Texas Water Code) directs the commission to give preference to applications in the following priority order: (1) domestic and municipal uses, (2) industrial uses (includes commercial fish production or aquaculture) , (3) irrigation of agricultural lands, (4) mining and recovery of minerals, (5) hydroelectric power, (6) navigation, (7) recreation and pleasure, and (8) other beneficial uses (includes stockraising, public parks, and game preserves). Further, the commission is to give preference "to appli- cations which will effectuate the maximum utilization of water and are calculated to prevent the escape of water without contribution to a beneficial public service" (Section 11.123, Texas Water Code). When there are conflicts between appropriators of State surface water the law directs that "the first in time is the first in right" (Section 11.027, Texas Water Code) , except that "any appropriation made after May 17, 1931, for any purpose other than domestic or municipal use is subject to the right of any city or town to make further appropriations of the water for domestic or municipal use without paying for the water" (Section 11.028, Texas Water Code). Since all surface waters of Texas are the property of the State, and since the responsibility for allocation of surface waters among appropriators and competing uses in Texas rests with the Texas Water Commission pursuant to State law, it is crucial to understand that the official identification of estuarine freshwater inflow needs, the alloca- tion and possible direct appro- priation of State water to meet these needs, and the equitable adjudication of water rights and claims are deeply intertwined. Further, this fact must be recognized by all involved in the definition and resolution of this coastal issue. Finally, a technical problem exists, inasmuch as studies have shown that the freshwater needs of an estuarine ecosystem are not static annual needs. That is to say, that a range of quantities of inflow is apparently both realistic and desir- able for an estuarine environment 91 because extended periods of inflow conditions which consistently fall above or below the maintenance level of the ecosystem can lead to a de- graded estuarine environment, loss of important "nursery" areas for estuarine-dependent fish and shell- fish species, and a reduction in the potential for assimilation of organic and nutritive wastes. For example, Texas estuaries severely declined in their production of economically important fisheries resources during historic drought events and began to take on characteristics of marine lagoons, including the presence of starfish and sea urchin populations. Likewise, when inflows are extremely high, fisheries production is lowered. The department's studies show that where the estimated season- al inflow needs of different fishery species are similar, the species reinforce each other's need; however, where species are competitive by exhibiting opposite seasonal inflow needs, a management decision must be made to balance the divergent needs or to give preference to the needs of a particular species. A choice could be made on the basis of which species' production is more ecologi- cally characteristic and/or econo- mically important to the estuary. Whatever the decision, even a well regulated freshwater inflow manage- ment regime can only provide an op- portunity for an estuary to be viable and productive because there are no guaranties for estuarine product- ivity. The results of recent studies being carried out under S.B. 137 will provide the legislature and others in decisionmaking positions some of the important information necessary to establish policies and management pro- grams for each of the State's important estuarine systems. De- cisions as to how each of these systems are to be managed, insofar as resolving the issue of the quantity of freshwater inflow to be made available from total freshwater sup- plies available to meet all fresh- water requirements within the State, must be made by the Texas Legisla- ture. Given these decisions, the Texas Department of Water Resources can then develop the necessary mech- anisms whereby the Texas Water Commission can administer the appro- priation of state-owned water to accommodate the freshwater needs for each of the estuarine systems. FEDERAL INVOLVEMENT The Federal Government plays an important, although usually indirect role, in maintaining the proper amount and timing of freshwater in- flows to the State's bays and estuaries. Federal policies in the area of water resources are directed to control of flooding, erosion and sedimentation, and construction of multipurpose water projects. The Department of the Army improves stream channels, constructs dams to impound waters for flood control pur- poses. The Water and Power Resources Service also constructs reservoirs; other Interior agencies, including the Fish and Wildlife Service, im- pound water in projects for municipal and industrial water supplies, rec- reation, and fish and wildlife fea- tures. The Department of Agriculture constructs runoff and erosion control works and small flood-water retarding projects. The Water Resources Coun- cil studies and assesses the Nation's water supplies and grants funds to the States for comprehensive water resource planning. The Department of the Army is under a blanket directive to examine its flood control projects to consid- er the probable effect of the 92 project upon any navigable water, which would include bays and estuaries, and to consider other uses that may be properly related to or coordinated with the project. [33 U.S.C. 701 (1917)]. Furthermore, all Federal agencies, in considering flood control projects, are directed to consider nonstructural alterna- tives to reduce flood damage, e.g., those which avoid water impoundment. DISCUSSION Question: Do you feel, in your position where you look at the balance of forces around the undeni- ably political basis of water decisions, that there is a strong enough constituency for estuarine resources to, in effect, carry the balance, so that the decisions that are made in Texas are going to be properly in balance in reflecting the vital role of water in estuaries and their importance to the public con- stituency there? Are these strong enough to balance? Answer: Well, I'm not sure whether it is strong enough to accomplish what one might want to do, but I can testify that there is a strong voice there. Legislation has been passed for example to establish policy to protect the bays and estuaries. Now in terms of securing the adequate financing to get it done on anything other than perhaps a project-by-project basis at the present time, perhaps not. Question: I think there is feeling among many people that if the public at large were only more cognizant of the resource values of estuaries that we would have a lot less problem in guaranteeing the water supplies we need. I have never been able to quite understand just the nature of the type of pro- motional or public relations effort that is needed, but you did mention public education and I don't know whether we are talking about trying to jet up a silent spring for es- tuaries or really get things started or talking about the more tedious and long-term effort of starting it in the school systems. Do you have any thoughts on that at all? Answer: Sure, I wish that it had been woven into the fourth grade fifty years ago, but it wasn't. When I refer to public education, I would also include public education in about all phases of water. Peo- ple don't understand hydrology or the hydrological cycle, but they know when they run short of water. You said this is a rainy state, but you have only seen one day's worth. We have been through one of the hottest, longest, driest summers I think I have ever spent in my life. We did have a significant quantity of water in storage and to the best of my knowledge, no industry shut down operations for one day from lack of water. Last year was a rel- atively wet year and, according to our information, had more fresh water in our eastern basins than was need- ed for estuarine systems or the lag effect would have shown the fish- eries production to be down. In terms of public education, we've got to do both. We've got to have mass information to the water-con- suming public, to business and in- dustry to allow them to behave in their own best interests and to be frugal users of water. People talk about conservation, but tell them to treat water as if they had to carry it from the spring house and they wouldn't use so much, I sup- pose. Widespread mass education as well as fundamental science educa- tion in the colleges in the public education system. 93 Question: My comment, I should probably address to Ken Collins also: One of the problems we are up against--I work in California and I realize there are similar problems in Texas--is that a lot of times by the time information is available, the resource is over al- located and there doesn't seem to be a mechanism to provide for the kind of flexibility that is needed, particularly when we are dealing with a biological system that we don't have adequate information for. If it takes 25 years of stud- ies, by the time those 25 years are gone, we have allocated what- ever water we might have needed or that we determine that we need. I'm wondering whether you foresee this? I think Texas may be on the right track, at least coming up with some interim guidelines. I'm sure that you maybe don't look at the studies that you have generated in a four-year period as the final answer and that there is enough flexibility left in the system in case you are wrong and that you can generate some water into the sys- tem. I think it is going to in- volve some ground water management which neither California nor Texas have and that is a toughie. Answer: You are asking how do we turn the clock back and suggest- ing ground water management is a way. I'm not sure that is going to help in some cases depending upon what you mean by ground water man- agement. Among the things that we need to do in many of our ground water cases is to get more recharge which means diverting even more of our surface water in a short run in- to ground water aquifers or shifting the load off declining aquifers in this growing economy onto more sur- face water, which is placing more competition on the surface water case. In our water rights justfica- tion program, we are adjudicating to the extent that water has not been used and rights are cancelled. That may free up some water. We don't know of cases in which we are pre- sently beyond the point where we have observed that we would need to go back and cancel rights in addi- tion to that. Question: I know that it is a basic problem in California water rights law also it is sort of a user-lose situation and it encour- ages agricultural users, in parti- cular, to use their water right be- cause if they don't they lose the right to use the water. There has to be a change in that. Answer: You are raising a question about an institution with which I happen to agree and, in that respect, that is how to bargain with present water rights holders. In our adjudication program, those rights that cannot be demonstrated to have been used, some are being canceled. Those that have not dem- onstrated having been used for a period of ten years are being can- celled. Our water commission is also writing permits for major pro- jects with requirements for recent years flow through and releases and return flows, in one particular case, into Corpus Christi Bay; a minimum quantity combination of re- turn flows and/or unused water right. The commission is also writ- ing term permits. Question: As Jerry has ex- pressed in California we have been fortunate to have at least water protection through legal water pro- tection plans in the bay delta sys- tem. I was wondering if Texas is planning to set specific water qual- ity standards with flow standards included for the protection of your estuaries sometime in the future. 94 Answer: In terms of water qual- quantity standards that are antici- ity, the department does establish pated at this point. The studies standards for each of the segments will be the residual at the present including the bays and estuaries for time against which all new permit any discharge. I do not know of any applications will be measured. 95 FEDERAL AND STATE COASTAL ZONE MANAGEMENT EFFORTS DIRECTED AT ESTUARIES AND FRESHWATER INFLOW Richard B. Mieremet Office of Coastal Zone Management National Oceanographic and Atmospheric Administration Washington, D.C. INTRODUCTION It was largely due to the ef- forts of many of you here that Con- gress was able to bring about the passage of the Federal Coastal Zone Management Act of 1972 (P.L. 92-583). Because research scientists and re- source managers were able to start identifying the importance of our estuaries and the problems asso- ciated with keeping them productive and because of the initiative shown by some coastal states, Congress de- clared that: o the coastal zone is a rich area in a variety of ways and is esstential for the well-being of the Nation, o that increasing competing demands for land and water uses have led to perman- ent and adverse changes to fragile coastal ecosystems, and o that it is in the National interest to effectively manage these resources. (See Section 302 for full text) It was clear that better de- cisions had to be made about these important resources. In order to do this, Congress declared some sound policies which to this day have been tried and tested true and provided some important tools to make it all possible, policies were declared to: National o "preserve, protect, and where possible, to restore or enhance" coastal re- sources , o to encourage and assist the state governments to devel- op, comprehensive coastal management programs which take all interests into accounts , o to encourage the partici- pation of the public as well as federal, state, and local government decision- makers in the development of these comprehensive pro- grams , o and with respect to the im- plementation of those pro- grams, to encourage states and regional agencies to establish "interstate and regional agreements, co- operative procedures, and joint actions regarding environmental programs. (See Section 303 for full text) Therefore, in order to make these decisions, it was important to provide the states with the tools ne- cessary to develop these comprehen- sive coastal management programs. Naturally, the largest incentive for 96 participation was the prospect of financial aid and it was not long before all 35 coastal states and territories were participating in the national program. MANAGEMENT TOOLS SECTION 305. Under Section 305 the coastal states were given up to five years to develop compre- hensive coastal management pro- grams which were to include tack- ling all the problems which focus- ed on the coastal zone. This is one of the great strengths of the program but it also has its drawbacks which I will discuss under PROBLEMS. Suffice it to say that estuarine vitality was just one of the many problems that states had to address. Nevertheless, we saw that most states spent some and even consid- erable portions of their grants to do the following. ences between upstream and downstream managers. Let me provide you with one such example. Last year in Texas' 305 grant, Task 11 contained four sub-tasks addressing freshwater in- flow studies. These funds were used to support the Texas Department of Water Resources to develop a "knowledgeable framework" upon which to base legis- lation and administrative policies. Provided was $114,000 to collect data, develop various models and facilitate coordination. Many undertook educational and public relations pro- grams which were deemed nec- essary for not only the survival of their develop- ing programs but for what was to take place under their implementation phase as well. o Inventory their resources which included surveying and mapping bays, estuaries, and wetlands . o Publish comprehensive bib- liographies and other docu- ments useful to managers, researchers and the public. o Undertake research to de- lineate just what the prob- lems associated with estu- aries were. This was useful for instance, in helping de- velop the appropriate coastal zone boundaries, policies for management and institutional linkages. This last aspect is important since in many cases we have the differ- Some of you here have taken part in these various endeavors. Total expenditure under Section 305 came to approximately $70 mil- lion. It is, of course, impossi- ble to state just how much of that was spent solely on the subject of freshwater inflows and estuaries because so many of the studies which were undertaken were inter- related with other subjects. During this time, OCZM did attempt to provide some technical assistance to the states through such sources as the book entitled Coastal Ecosystems which was written by our distinguished chair- man. SECTION 306. Section 306, Program Administration, is not an 97 altogether different story but does go a little further. After the states have a federally approved management program, funding be- comes a longer term (8 years) prop- osition which will allow for more in-depth research and studies nec- essary in making sound management decisions on say, for example, the siting of a facility. Almost all states are now able to provide substantial funding to local governments which are usually the first in the decision-making pro- cess, proponents of the activities, and have the least in their pocket- book to look at the implications of their actions. Local governments are developing their own site-specif- ic comprehensive programs which will allow all parties to get a better handle on the problems if they become involved at the appropriate stage of development. Some of the Gulf States are just now in the process of getting their programs approved. Alabama is ap- proved and we hope Louisiana and Mississippi will be approved shortly (programs were approved in September 1980) . Florida and Texas are cur- rently in the Public Hearing Draft stages . Even though state participa- tion is voluntary, the Coastal Zone Management Act is substantive as well as procedural. States are re- quired to develop enforceable poli- cies to manage coastal resources. I would like to give a few short examples of some of the policies which were developed by the states which address our topic of concern. California: "30231. The bio- logical productivity and the quality of coastal waters, streams, wetlands, estuaries, and lakes appropriate to maintain optimum populations of marine organisms and for the pro- tection of human health shall be maintained and, where feasible, re- stored through, among other means, minimizing adverse effects of waste water discharges and entrainment, controlling runoff, preventing de- pletion of groundwater supplies and substantial interference with surface waterflow, encouraging waste water reclamation, maintaining natural veg- etation buffer areas that protect riparian habitats, and minimizing al- teration of natural streams." (The California Coastal Act of 1976 - PRC 30000 et. seq.) Oregon: Goal 16 - Estuarine Resources is a comprehensive goal enforceable by law. It addresses many issues about estuaries and re- quires comprehensive plans to take these into consideration. It is too lengthy to even summarize here but there is one interesting aspect I wanted to highlight. Namely, many states recognize that coastal zone management affords a good opportunity for restoring degraded estuaries. Under the mitigation requirements of the goal, it is suggested that: "Estuarine areas removed from effective circulation by causeways or other fills, where circulation can be restored or improved through replacement of the causeway with pilings or culverts." (Oregon Statewide Planning Goals and Guide- lines 16-19 for Coastal Resources, Effective: 1 January 1977). New Jersey: New Jersey has developed policies for surface and groundwater uses and for special areas such as shellfish beds re- lating to freshwater inflows. For example, the Groundwater Use Pol- icy (7:7E-8.6) states: "Coastal development shall demonstrate, to the maximum extent practicable, that the anticipated groundwater 98 withdrawal demand of the develop- ment will not cause salinity in- trusions into the ground waters of the zone, will not degrade ground- water quality, will not signifi- cantly lower the water table or piezometric surface, or signifi- cantly decrease the base flow of adjacent water courses. Ground- water withdrawals shall not exceed the aquifer's safe yield." (New Jersey Coastal Management Program, August 1980, page 220). Louisiana: Guideline 9.1 addresses uses that result in the alteration of waters draining into coastal waters and states that: "Upland and upstream water manage- ment programs which affect coastal waters and wetlands shall be de- signed and constructed to preserve or enhance existing water quality, volume, and rate of flow to the maximum extent practicable." In addition, the program is desig- nating wetland areas suitable for enhancement by freshwater diversion as Areas for Special Management. (Louisiana Coastal Resources Pro- gram, 1980, page 62 and 111). In addition to using the en- forceable policies to make manage- ment decisions, Section 306 funds can be used to prepare "special area management plans" or address "areas of particular concern." This means that funds could be used to identify specific resource- use conflicts which create the es- tuarine management problems and propose and implement solutions to those problems. SECTION 307. Section 307 deals with Federal consistency and even though it has been somewhat controversial in its implementa- tion, it can be useful for state coastal managers in addressing Federal activities such as dam construction which may take place outside of the coastal zone in the upper watersheds and have impacts on the coastal estuaries. SECTION 308. The Coastal Energy Impact Program has provided both planning and study funds and also construction funds to help ameliorate the impacts on coastal resources created by energy impacts either directly or indirectly. This is a multi-million dollar pro- gram of grants and loans and has been used for such purposes as constructing a freshwater diver- sion siphon in St. Bernard Parish called the Violet Siphon. A recent article in PLANNING describes the background of the necessity for this project and the role of coast- al management. It states: "When the state initiated efforts to adopt a coastal zone management act of its own to comply with federal funding requirements, Section 305 funds became available and planning for wetlands and coastal areas in St. Bernard went into high gear. There were some reservations about additional layers of federal bureaucracy and regulations being imposed on the area, but after the MRGO (Mississ- ippi River-Gulf Outlet Canal) experience, support from a federal agency to solve some of the problems caused by yet another federal agency was more than welcome. . .The police jury applied for and received a 100 percent federal grant to construct a freshwater di- version siphon--two 50-inch pipes from the river over the levee and into the Violet Canal. The grant for this project was the first 99 environmental mitigation construction grant funded under the Coastal Energy Impact Pro- gram of the U.S. Office of Coastal Zone Management." We have many other examples of requests and the use of funds which specially deal with freshwater in- flows, saltwater intrusions and the vitality of estuarine resources such as a $60,000 grant to Louis- iana to study saltwater intrusion in Tangipahoa Parish and $1,000,000 to Louisiana coastal parishes to construct and rehabilitate oyster reefs on natural seed grounds and to relay oysters from polluted to approved areas in Calcasieu Lake. These are projects which probably would never would have been funded otherwise. The costs in most cases are much to great for local governments to bear and in many cases state governments . SECTION 309. Section 309 pro- vides for interstate grants and even though it has never been fund- ed, it contains a provision of law which one day may be found useful in dealing with freshwater inflows. This section allows two or more coastal states to negotiate, and to enter into, agreements or com- pacts which the states deem to be desirable and which are binding and obligatory upon any state or party without further approval by Congress . SECTION 310. Research and technical assistance is one part of the CZMA which we badly want to see funded. Based upon needs identi- fied by the states and other prior- ity items identified by OCZM, this could be one additional resource in helping get at estuarine problems. SECTION 315. Estuarine sanc- tuaries in some cases have been helpful in getting to the problem of freshwater inflow, the most not- able is the Apalachicola Estuarine Sanctuary in Florida. During its establishment as a sanctuary, it was recognized that water inflow to the Apalachicola River and Bay was largely dependent upon the Chattahoochee and Flint Rivers in Alabama and Georgia. It was an im- portant tool in focusing the con- cern of the upstream users with the downstream management goals. Consequently, there were success- ful negotiations between the three states and they have jointly pro- posed to the Water Resources Coun- cil to undertake a Level B Study which will lead to further under- standing of the drainage from these three rivers and the competing de- mands for this winter. The purpose of the sanctuaries is to establish outdoor laborato- ries and to conduct research and edu- cational programs. This is one area where we would like to see more coordinated research taking place in order to make more enlightened management decisions affecting estu- aries . PROBLEMS While coastal zone management has many significant tools which are being used and will be used in the future to address problems re- lating to freshwater inflows to estuaries, it obviously can not cure them all. BOUNDARIES. In order to ad- dress inflow problems, one must generally view the entire water- shed or wherever major obstructions begin. In some states, this water- shed transcends the coastal zone boundary which they have delineat- ed. The states must draw a line 100 somewhere and OCZM has generally supported the state process in defining their boundary. Some states have included all or almost all of their state as the coastal zone be- cause of the watershed principle and others have included coastal mountain watersheds. Still others have narrow boundaries which stop at the 5 o/oo salinity line of the estuary and riv- ers. Extra efforts are needed to ensure good coordination of govern- mental actions. In order to shore up this potential weakness, some states have developed Memoranda of Under- standing, required consistency of their own state agencies with the coastal policies, and provided fund- ing to other state management agencies to assist in a cooperative mode in addressing the multi-juris- dictional problems. cial resources needed to address the issues . RESEARCH COORDINATION. Much re- search is being conducted on the health of our estuaries, yet many of the major questions are unanswered and there are still conflicting theories. The academic community, state and the federal governments are expending significant amounts of time and money on this issue. OCZM is contributing as well, but there needs to be some coordination of the resources so that they are utilized to the best advantage. There has to be a better marriage between basic and applied research and be- tween the scientists and the resource managers . COMPREHENSIVE PLANNING. Coastal zone management calls for a balance in decisionmaking. This often requires some compromises be made between preservation and development. It is likely that there will be times when the importance of freshwater inflow will get lost in the priori- ties where there are conflicting national/state and local interests. COST. While coastal management can currently assist in mitigation and restoration projects, the funding authorization is not projected to be long term. We must learn quickly from past mistakes and avoid the high costs of restoration in the future. SECTION 306/308 RELATIONSHIP. Section 308 is the best funding source for restoration and mitigation projects, but states which do not participate under 306 are not eligible for 308 funds. There may be states that choose not to participate but may have key estuaries which may CONCLUSION The Coastal Zone Management Act was passed because of concerns over estuaries and other coastal re- sources. Financial assistance and management tools are providing in- centives to state and local govern- ments to begin to address problems associated with freshwater inflows or the lack thereof. Special area management planning, enforceable policies, and improved coordination are being brought to bear on the de- cisionmaking process. Mitigation and restoration projects can help al- leviate some of the past problems. While coastal zone management cannot solve all of the inflow problems, especially for some of the larger rivers which transcend the coastal zone boundary, it can be a signifi- cant ally with other governmental entities in making better decisions and providing some support with which to do it. 101 LITERATURE CITED Meeks , Gordon, Jr. A Louisiana Swamp Story, Planning Vol. 46, Number 2, February 1980. DISCUSSION Question: Clark. I feel a little more hopeful now that the coastal management program will involve it- self in watersheds, but you've got one little problem up there, it goes something like this: we con- servationists over the years have taken on the dredgers , point-source polluters, the wetland fillers, and real estate interests. We have even taken on the nuclear plants. Now it is 1980 here on the coast and I ask who is next? Who are we missing? Who are we not taking on? Well of course, I think we all know that it is time to take on the farmers. The CZM won't take on the farmers. The Corps of En- gineers refuses to take on the farmers. The EPA tried it, got whipped and quit. That is my ques- tion, who will take on the farmers? Answer: Miermet: It is a very difficult thing. California, in plan- ning for their coastal zone, has a much larger boundary when they tried to address the issue of the very pro- ductive agricultural lands there and they tried to get some handle on the management aspect but that was re- jected and the boundary was quite a bit narrower than the coastal commission had proposed. It took out the forests and the agricul- tural lands. I think in a state like Louisiana when you fly over it, you see the wetlands and the agricultural lands side by side. Most states do have some policies that address agriculture and the purposes. I think that most states find that as being the highest use of the coastal zone, however, it is not so much a regulation as it is some other aspect of trying to protect agriculture. Question: My name is Chris Temke. I'm with the Florida Depart- ment of Natural Resources: I just wanted to elaborate for a moment on a point that Ben made earlier this afternoon that there was a definite lack of data which are needed to understand what the problems are in the estuaries, and what steps should be taken to resolve the problems and to mitigate these problems. I think the national estuarine sanctuary problem fits quite well in trying to answer this question. One of the major purposes of the program is to set aside areas for long term research and education, to establish a data base, and to understand what a relatively or completely undis- turbed system is like, and I feel as though these areas are new. They have only been in existence a few years and should be looked at quite closely by people that are thinking about doing research. Certainly, in the area of Rookery Bay, I'm trying actively to bring university people down here to do research, so we can develop a data base in this area which can be used to help develop a coastal zone policy. Comment: Clark. Beyond this research and education, I have no- ticed lately that some of the estu- arine sanctuaries have an agenda of conservation or resource management as well. Certainly Apalachicola , Rookery Bay, and Alcorn Slough have really increased the state-of-the-art as far as estuarine management is con- cerned. I think that there is more progress made in ultimate long-term benefits and coastal zone manage- ment in the estuarine sanctuary 102 program than any other part of the CZM program. I really am very enthusiastic about that. I hope we can invent something that will widen that out so that we don't have to restrict this type of de- signation of Federal assistance to local areas and unit resources. They will not have to restrict research and education to repre- sentative areas here and there, since every estuarine community that wants it, ought to be able to have the benefit of technical assistance and the designation and what comes with it in the way of Federal, state, and local cooperation and partnership. I think it is really a dynamite program. 103 CORPS OF ENGINEERS POLICIES ON FRESHWATER INFLOW Walter B. Gallaher U.S. Army Corps of Engineers, Dallas, Texas INTRODUCTION It is indeed a privilege to par- ticipate in today's panel session. I am substituting for Brigadier General Hugh Robinson, our Division Engineer, Southwestern Division. General Robinson asked that I express his sincere thanks to the USFWS for its ivitation and sends his sincere re- grets for being unable to participate in today's session. General Robinson did express his keen interest in this most important symposium and believes that the results and conclusions reached at this 3-day symposium will be most important in guiding our fu- ture efforts in conserving the valu- able fishery and shellfish resources of our Nation's estuaries. CoKI'S CAPABILITIES AND CONSTRAINTS The Corps of Engineers had plan- ned, constructed, and is presently operating more than 400 reservoirs across the United States. However, the water is owned, and water rights are controlled by individual states, usually a state water resources board within the state where the project is operated. Therefore, with the water use controlled by others, release of waters downstream or use for pur- poses other than authorized purposes are not usually possible without the state's agreement. During the planning process, various water-use needs, including mitigation require- ments, are considered and those fea- sible uses provided for in the proj- ect plans. Even reservoir releases for mitigation need state concur- rence to ensure the water is not di- verted before it serves the mitiga- tion purpose. The degree of control over wa- ter uses and the availability of so called "surplus water" vary with the states. Generally in the western states, particularly in the semiarid areas, water uses and availability are much more closely regulated than in the eastern states where more wa- ter is usually available. In states such as New Mexico and Texas, where all the available water has been ap- propriated, the states exercise full control over water use. In some areas, the Corps has some degree of flexibility in operation of proj- ects and releases of flood waters . In such cases, it is possible to work our water-level management plans for reservoirs and downstream re- leases for the benefit of fish and wildlife, and we have implemented these plans at many projects. Several existing authorities provide the Corps with direction to study and develop solutions to in- stream flow problems: a. Specific project or basin studies to solve a particular pro- blem. 104 b. Sec 216, PL 91-611, Com- pleted Project Review. This section authorizes review and report to con- gress of the operation and mainte- nance of completed projects when found advisable due to significant changes in physical or economic con- ditions . c. Sec 102(b), PL 92-500. This section makes it clear that the Corps will determine the need and value of storage for all stream- flow purposes other than water qual- ity control. This sounds all well and good; however, the problem of planning storage for fisheries needs is compounded when projections of the components of future flows and their relation-ship to state water laws are considered. d. Sec 22, PL 93-251, Compre- hensive Planning Cooperation with the states. Mechanisms exist to do limited project work as re-quested by specific states. e. Sec 65, PL 93-251, Water Quality Storage. This section per- mits conversion of water quality storage in authorized reservoirs if it is "not needed, or is needed in a different amount" to other authorized purposes of the project when Environmental Protection Agency (EPA) determines that such storage is unnecessary. f. The continuing responsibili- ty for project operation and mainte- nance requires frequent reanalysis of our water control management to en- sure instream flow procedures are the best use of the resource to accomp- lish the authorized purposes. President Carter, in his Memo- randum on Environmental Quality and Water Resources Management, 12 July 1978, directed all Federal agencies to cooperate with states to improve the operation and maintenance of existing water resource projects to address instream flow needs. The President's Memorandum stated in part: "In cooperation with the states, federal agencies shall im- prove, where possible, the opera- tion and management of existing water resources projects to protect instream uses. While not interfer- ing with state laws and responsibi- lity, federal agencies shall set a strong example in recognizing and protecting legitimate instream flow needs . " "In the planning stage, federal agencies shall establish and provide for the streamflow necessary to main- tain instream needs below dams or other facilities. For existing water resources project legislation that now lacks provisions for maintaining instream flow, and where commitments and economic feasibility permit, fed- eral agencies working in cooperation with the states shall develop legis- lative amendments to correct this situation. " Instream flow needs have per- plexed water resources planners for some time. There have been several reasons why the instream issue has been unclear. First, it is not un- common for planners and developers to see instream uses and out-of- stream uses as being in conflict. Historically, the legal and insti- tutional systems favored out-of- stream uses. Second, many agencies have a narrow perspective of the problem because their agency mis- sion is oriented to one use or anoth- er. As a result, even agencies ex- ercising control over related in- stream flow uses have tended to dif- fer in the development of criteria 105 and methods. Third, the use of the term "minimum flow" has created prob- lems. Traditionally, minimum flow has been used to describe the ulti- mate minimum that developers must leave in the stream, having taken all the rest. Overuse of this term has tended to crowd the real issue-- that there are instream uses, each having a specific range of flow re- quirements. For the purpose of this presentation, I am using this defini- tion of instream flow uses: "All beneficial uses of water in a stream channel, such as fish and wildlife habitat, navigation, hydropower, rec- reation, and aesthetics." There are four general categories in which in- stream flow problems can be classi- fied: (1) quantity, (2) quality, (3) physical barriers, and (4) flow fluc- tuations. Instream flow problems can also be a combination of these four categories. Furthermore, problems may result from the cumulative effect of several small projects, any one of which by itself would not cause in- stream flow problems . proposed, where commitments and eco- nomic feasibility permit, will be submitted by Corps districts as op- eration and maintenance items for in- clusion in the President's budget. As we continue our evaluation of instream flow problems and needs, consideration will be given to de- veloping a separate program and funding source to solve instream flow needs, such as a line item in the President's budget. In addition to the above, all existing projects here in the South- western Division are being evaluated with respect to stream flows for fish and wildlife needs. This eval- uation is not of the detail fre- quently associated with the planning of new projects. The time and fund- ing constraints require that this information be based upon data on- hand. This information will, of course, be incorporated into the overall evaluation of instream flow needs . Implementation of the Presi- dent's directive has brought about increased emphasis by the Corps on water control management in our projects. As a first step in es- tablishing a Corps-wide approach to meeting the President's directive, the Corps is currently making a project-by-project evaluation of all its existing water resources proj- ects. These evaluations will be used to assess the magnitude of instream flow-related problems and needs, the potential costs re- quired to meet these needs, the opportunities that might exist for enhancing instream flows affected by projects, and will serve as a basis to establish priorities in carrying out the necessary action. Until the information is gathered and evaluated, high priority proj- ects for which solutions have been It is the policy of the Chief of Engineers that reservoir regula- tion procedures be evaluated con- tinually. The objective of this policy is to improve water manage- ment in light of changing condi- tions . There are a number of available methodologies for determining the water requirements for instream uses, but none of these methods is uni- versally applicable. Policy stud- ies related to instream flow re- quirements are being conducted un- der the auspices of the Institute for Water Resources. Technical stud- ies are presently ongoing under the Corps Environmental and Water Qual- ity Operational Studies Program at the Waterways Experiment Station. These studies will assist the Corps in future planning needs in project 106 formulation studies. Areas of anal- ysis include: (1) evaluating tech- nical methods presently being ad- vanced through other federally spon- sored programs, such as the Coopera- tive Instream Flow Group in Fort Collins, Colorado, (2) appraising the impact of existing compacts op- erating at state and river basin lev- el; and (3) reviewing and apprais- ing emerging instream flow policies being developed. With regard to our Regulatory Functions Program, we will review all existing and potential permit applications to determine: (1) if at the time of permit approv- al, instream flows were cited as a need beyond that identified by the applicant, and (2) if any pending applications during a public inter- est review have recognized the need for instream flows. Conflicts will need to be cited and solutions pro- posed. SUMMARY Instream flow needs is a con- cept whose time has arrived. Un- fortunately, the problem has not been defined explicitly to allow the development of a corrective uniform methodology. An intensive evalua- tion effort is being made to define the magnitude and extent of the prob- lem so that an action program can be formulated. It is conceivable that in the not-so-distant future with expected human population growth in the United States and consequent in- creased demands on consumptive use of stored water, new reservoirs will be planned to satisfy all iden- tified needs. These may include storage and releases earmarked for replenishing freshwater inflows to bay and estuarine areas. However, there are many problems that will have to be overcome before this can be done. First, higher priority must be placed on water use for such purposes as fish and wildlife, and second, someone will have to pay for the storage and O&M costs. Further, once you have ironed out these prob- lems, there are other constraints to getting this water downstream to reach the bays and estuaries, such as channel losses, encroachment on water use, etc. The Corps is dedi- cated to work with all concerned parties to best meet all the water needs of our Nation—including freshwater flows to estuaries. DISCUSSION Comment: You mentioned the concept of dilution as the solution to pollution. In California we have been told that is one reason we can't have instream flows because dilution is not a solution to pollu- tion. I advise people to counter that by saying that low flows make no shows out of Cohos . Comment: I'm Jerry Valence from the California Resources Con- trol Board. One of the concerns that we have had in California re- lates to economics. I get the feel- ing that a lot of people are going to try to quantify economically the benefits of estuaries, and I suggest that there is a potential danger in that you are not going to be able to quantify adequately what we con- sider to be intangible benefits of estuaries. I think that maybe some- thing we may want to consider in our deliberations over the next few days is that there are intangible bene- fits, such as the benefit of being able to take your grandson fishing fifty years from now. What kind of benefit is that for estuaries? I'm 107 not sure we will ever be in the po- sition of quantifying all those im- pacts economically. I think what we need to do is set forth what we feel are appropriate goals to meet and then try to meet them. Economics is a part of that, but I don't think you can do a dollar for dollar com- parison and expect estuaries to come out on the top every time. There are other benefits which we just can't quantify that we need to recognize in our deliberations Reply: I would accept that there are hopes and expectations of our society that are beyond what we can measure in dollars and that is a tough one. Anybody else care to com- ment on that subject of economics? I know it is a burning issue that we are never going to solve. I think we are burned out. 108 BANQUET ADDRESS Honorable Robert L. Herbst Assistant Secretary of the Department of the Interior, Fish, Wildlife and Parks I always enjoy coming to Texas and often recall the first time I made a speech here. I was commis- sioner of Natural Resources in Min- nesota, and, before the meeting, was complaining about my problems to a group I had just met. I said, "I've got 4,000 employees, a yearly payroll of 189 million dollars, and I oversee 57 million acres of land. What a headache. " One of the listeners, a wind- burned Texan, said, "Son, I can understand your complaints, your outfit is almost as big as my ranch. " It was that same night after my speech that I knew I had said something to offend. As I sat down at my seat on the dais, a brawny cowboy pulled a chair up next to me and placed his six-shooter on the table. I must have turned a little pale, because he said, "Don't worry ain't nuthin' gonna happen to you. We'd just like to get the guy who invited you here." Well, I hope that won't be the case tonight, but I am prepared to take my chances because your sym- posium subject is tremendously im- portant and because what government does and has done has great impact on the water, coastline, and estu- aries of America. For those of us concerned with the preservation and conservation of our national, natural resources, the decade of the seventies was an extraordinary one--one marked by great public education, interest, and support. And because that pub- lic support was reflected in a series of legislative landmarks and by many positive executive and ad- ministrative acts at state and Fe- deral levels, we look back with great pleasure and satisfaction on an Environmental Decade. Yet, for all of that, while estuarine concerns were not totally ignored, they were not nearly as central a concern as we might have hoped. You, however, persisted in your research and your application of existing knowledge and I salute you for that. You have known what many others seem to have ignored: that many of our estuaries are producing less and show less diversity than in the past--seriously ill, if not slowly dying. You know that estuaries help feed a hungry world and that their destruction leads to certain and inevitable misery. You know that we cannot take the most productive ecosystems in the world--the natural factories where fresh water and salt water mix--the production sites, if you will, of immense populations of commercially valuable shellfish, crabs, and finfish, treat them in- differently and casually and expect to survive well. You know that we cannot drain, fill, pollute, or destroy estuaries in the name of progress or as a simple sin of greed 109 without ultimately inviting wide- spread distress. The coast—barrier islands and estuaries--may indeed be America's last frontier. How we behave here may determine to a great degree what the quality of life will be for fu- ture generations. Hopefully this symposium will itself be a watershed in turning both professional and public at- tention toward estuaries and in turning destructive forces away from them. You deserve and you will have important allies in this and we will need them in the decade ahead of us--one which may be more difficult for environmentalists than the one just past. Our history, in many fields both social and scientific, has been one of great activity followed by quies- cense, of movement upward, followed by rest on a plateau. Add in un- certain economic conditions and a strong budget-cutting impulse on every level of government and the eighties seem filled with difficul- ties . Despite all of that--despite obstacles, pitfalls, and those to whom our cries mean nothing—there is hope. There is hope that the people's attention will not stray from our concerns and the Nation' s — nor the world' s— environmental needs. President Carter has declared this year, "The Year of the Coast," and we in government have tried to follow his direction and to reach for his goals. Tonight, I want to restate his goals, speak of what we are doing, knowing what he has set forth is non-partisan and non- political . He said in his 1979 message on the environment, and I quote, "Am- erica's coastlines are extraordin- arily varied, productive and beauti- ful. The coastal zone is subject to unusual pressures, both from nat- ural causes and human activities. The opportunity of our citizens to enjoy beaches, bays, and marshes is often threatened..." He then set as his goals: To protect significant national resources such as wetlands, es- tuaries, beaches, dunes, barrier islands, and fish and wildlife. Manage coastal development to minimize loss of life and pro- perty from floods, erosion, saltwater intrusion, and sub- sidence. To assist in siting of energy, defense, transportation, and recreational facilities. To increase public access. To preserve and restore histor- ic, cultural, and aesthetic coastal resources. And to coordinate and simplify government decision-making. Some progress has been made in meeting these goals — some substan- tial progress, I think— but it hasn't been easy and it hasn't been total. What happens in my home state of Minnesota where the Mis- sissippi begins may seriously affect Louisiana where it ends. Surely what happens in St. Louis and Mem- phis and the lands around the lower river does. It is obvious yet it 110 seems a lesson which has to be re- learned by some almost daily. Management and protection of the coastal zone will never be sim- ple because many people and many diverse interests and areas are in- volved. We must tie together in- land river and watershed planning and management to coastal planning and management. They cannot be isolated, one from the other, pretending in an Alice in Wonderland World that fresh water, sediments, and nutrients will miraculously appear in estua- ries without being carried there by our streams and rivers. The people I work with at the Department of the Interior—in the Park Service, in Fish and Wildlife particularly, and in the Heritage Conservation and Recreation Ser- vice—understand all of this inter- dependence well. They understand and take seriously their special responsibility for our coasts. We oversee 115 national wild- life refuges in the coastal zone and they cover 7.2 million acres— more than that Texas ranch. We have 40 national park service areas along our coast, including some of our most sensitive barrier islands. HCRS , the Heritage Conservation and Recreation Service, newer and less well known than Parks or Fish and Wildlife— has an awesome respon- sibility in working to preserve the barrier islands which, of course, surround many of our estuaries. These islands functioning in a life-giving rhythm with estuaries and saltwater marshes and dunes have qualities unequalled and virtually unparalleled. They are unique in their ani- mal and plant life, providing a fav- orable habitat not only for fish and shellfish, but for reptiles, birds, and mammals. Barrier islands provide protec- tion for our mainland and recreation- al activities of a special sort for millions of people whose souls are refreshed and whose spirits soar like the osprey who nest and feed nearby. This is but one example of in- creased Federal awareness and in- volvement in the environmental health of our coasts. There are others. The responsibility to identify "approximate freshwater needs" of estuaries was given to the Water Resources Council in 1975 and it has an "independent review" func- tion of all federally-funded water projects. That is significant. Our Fish and Wildlife Service, through its responsibilities in im- plementing the coordination act, has considered the freshwater needs of estuaries in its assessments. We know that there are no reserved Federal water rights for estuaries, but we intend to protest, or cur- tail where we can, any action by another Federal agency or by a state agency or by individuals or corporations which will result in a changed ecology in our national wildlife refuges or our national parks along the coasts. Let me list several other proj- ects which some of you are involved in, but which all of you should be aware of. The FWS has ongoing studies in the Nueces-Corpus Christi and the Matagorda Bay estuaries of the 111 Texas coast to determine the effect of reducing freshwater inflow. The FWS is working closely with the U.S. Army Corps of Engineers in New Orleans to develop plans and methods for reintroducing fresh water into marshes and estuaries along the Louisiana coast that have suffered saltwater intrusion. On the West Coast, the FWS is working with the State of California and the Water and Power Resources Service to develop water plans that will protect fish and wildlife habi- tats in the Sacramento-San Joaquin estuary. The Pacific Northwest Basin Commission is developing a data base for planning the management of the Columbia River estuary. The FWS National Coastal Eco- systems Team has completed ecological characterizations--mostly from avail- able information — on six segments totaling 2,100 miles of U.S. coast- line. The FWS is making a strong ef- fort to protect the remaining bottom- land hardwoods along a number of riv- ers, including the Mississippi. It's interesting, by the way, to note that 56 percent of bottomland hardwood habitat in the lower Missis- sippi River alluvial plain was cleared between 1937 and 1978-- primarily for agriculture. Its ef- fects were horrendous and I'd wager that national gains were far less than national losses. To prevent further losses--some irrevocable and beyond repair--we are going to have to have a more sensible approach to water resource planning. In order to protect our river and estuary ecosystems which are so vi- tally connected physically and ecologically, we need a system of coordination and cooperation between engineers, planners, ecologists, na- tural resource managers, economists, and citizens. Rachel Carson, in many ways the patron saint of our environmental in- terests, once quoted Albert Schweit- zer who said, "Man has lost the cap- acity to foresee and forestall. He will end by destroying the earth." You at this symposium are among a small party devoted to foreseeing and forestalling frightful events. With the help of your wisdom, maybe we will not end by destroying the earth. At the very least, we will start by protecting the estuaries which give life. 112 CHAPTER 1 FRESHWATER INFLOW STUDIES ALONG THE MID- AND NORTH ATLANTIC COAST 113 CHESAPEAKE BAY LOW FRESHWATER INFLOW STUDY Alfred E. Robinson, Jr. Chief, Chesapeake Bay Study Branch, Baltimore District U.S. Army Corps of Engineers, Baltimore, Maryland ABSTRACT Chesapeake Bay is the largest estuary on the Atlantic coast of the United States and one of the more im- portant estuaries in the world. It is nearly 200 miles long and varies in width from 3 miles to 30 miles. Like all estuaries, it depends upon the inflows of freshwater to maintain its salinity regime. Salinity varia- tions, spatial and temporal, consti- tute the most significant physical parameter influencing the circulation dynamics of the estuary and the types of aquatic species which reside in it. The quantity of fresh water flowing into the Chesapeake may be substantially reduced in the future due to a marked increase in the con- sumptive use of water. The Corps of Engineers Low Freshwater Inflow Study was conceived as a result of the con- cern over this increased consumptive use. The objectives of this study are to assess the environmental, eco- nomic, and social consequences of these reduced flows and if appropri- ate, to formulate criteria for mini- mum freshwater inflows. A major por- tion of this work will be based on the results of a series of tests con- ducted on the Chesapeake Bay Model. INTRODUCTION The Chesapeake Bay is the larg- est estuary on the Atlantic coast of the United States and one of the more important estuaries of the world. The bay is about 200 miles long and varies in width from about 3 miles near Annapolis to about 30 miles at its widest point near the mouth of the Potomac River. It has a free connection with the waters of the Atlantic Ocean at its southern ex- treme and is connected near its northern extremity to the Delaware Bay through the Chesapeake and Dela- ware Canal. The tidal shoreline of the bay and its tributaries is about 7,000 miles long while the water sur- face area is about 4,300 square miles. The surface area of the bay proper is about 2,200 square miles and its mean depth is less than 28 feet. The entire system, including the tributaries to the head of tide, averages about 21 feet deep. There are, however, deep holes which occur as long narrow troughs. These troughs are thought to be the remnants of the ancient Susquehanna River Valley which have not been filled by post- Pleistocene sediments. The deepest of these holes (175 feet) is locat- ed near Kent Island where the Chesa- peake is at its narrowest. Figure 1 is a map of the Chesapeake Bay Area. The Chesapeake Bay receives wa- ter from a basin over 64,000 square miles in area. There are more than 50 tributary rivers with widely vary- ing geochemical and hydrologic char- acteristics contributing fresh water to it. The largest river on the East Coast of the United States, the Sus- quehanna, drains 42 percent of the basin. The Potomac River drains 22 percent, while the Rappahannock- York-James system drains about 24 percent. 114 Figure 1 Map Of Chesapeake Bay 115 The mean tidal fluctuation in Chesapeake Bay is small, generally between 1 and 2 feet. Saline water intrusion is highest along the east side of the estuary due to the in- fluence of the coriolis effect and the fact that the larger rivers are on the western shore. Salinities range from about 33 ppt inside of the mouth of the bay to near zero at the north end of it and at the heads of the embayment's tributary to it. Sa- linity variations, spatial and tempo- ral, constitute the most significant physical parameter influencing the circulation dynamics of the estuary and the types of aquatic species which reside in it. The ebb and flow of tides are the most readily perceptible water movements in the Chesapeake. Average maximum tidal currents range from less than 0.5 knots to over 2 knots. The tidal currents along with wind supply the necessary energy for the mixing of salt water from the ocean and fresh water from the tributaries. Tides, being oscillatory by nature, do not function as a mechanism for the net transport of water, suspended solids, or dissolved material. With- in the bay proper and its major trib- utaries there is superimposed on the tidal currents a non-tidal, two- layered circulation pattern that provides a net seaward flow in the upper layers and a flow up the estuary in the deeper layers. The physical and chemical dy- namics of the estuary make it a biologically special place. Salinity variations within Chesapeake Bay have allowed colonization by aquatic organisms of both fresh and salt water origin. Freshwater biota re- main in the fresher to slightly brackish portions. Many marine animals return to fresh water to reproduce. Also, with the aid of estuarine currents, the eggs and larval forms of some species are transported to less saline waters to hatch and develop. PROBLEM IDENTIFICATION Like all estuaries, Chesapeake Bay is dependent on the inflow of freshwater to maintain its salinity regime. The species that live in the bay year round and others that utilize it only in various portions of their life cycle are generally able to survive the natural daily, seasonal, and yearly variations in salinity. Drastically reduced fresh- water inflows during droughts or re- ductions of less magnitude over a longer period of time can impose en- vironmental stress. This may threat- en the health or even the survival of species sensitive to particular ranges of salinity, or may limit the spawning opportunities of other estu- arine species. Changes in freshwater inflow can also alter existing estu- arine-f lushing characteristics and circulation patterns. In short, the character of Chesapeake Bay and the health and well being of the eco- system depend on established physi- cal, chemical, and biological pat- terns in the bay. These are, in turn, intimately related to the volumes of freshwater inflows and the seasonal variations in these flows. In recent Corps of Engineers' studies it was found that, if present trends continue, the future quantity of fresh water flowing into Chesa- peake Bay could be substantially less than it is today. This predicted re- duction is primarily a function of increased consumptive use of water from the bay's tributaries resulting from an increasing population, the need for more food, an increasing level of economic activity, advances in technological processes, and in- creasing use of evaporative cooling 116 processes . The population of the Chesapeake Bay Region is expected to nearly double in the next 50 years. The majority of these people will prob- ably be served by central water sup- ply systems and it has been demon- strated that a typical community will return to a stream only 75 to 90 per- cent of the water withdrawn from it. It is possible that none of the water would be returned if an inter-basin transfer is involved. An increasing population needs more food. Because of limited land resources and economic factors it will probably be necessary to sub- stantially increase irrigation prac- tices. Almost all of the water used for this purpose never returns to the system or takes so long to return that, for all practical purposes, it is considered lost. As economic activity expands, more water will be needed for in- dustrial processes. This alone would result in a substantial increase in consumptive use. There is, however, a definite trend toward an increased use of processes such as cooling towers, which involve the evaporation of water. The consumptive use of water associated with this is often markedly greater than some other types of processes. Nearly every tributary to Chesa- peake Bay will be subjected to the consequences of increased consumptive uses of water. Table 1 has been pre- pared in order to assist in placing the magnitude of these uses in per- spective. Shown on this table are the actual discharges of the Susque- hanna River during August, September, and October of the drought year 1964, the anticipated consumptive uses of water in the year 2020, and the con- sequential reduced freshwater in- flows. These reduced inflows have been adjusted to reflect the influ- ences of several dams which have been constructed since 1964 and, where appropriate, the discharges from wastewater treatment plants. Under low flow conditions these consumptive uses often constitute a considerable portion of the natural flow in a river. For instance, the losses in the Susquehanna River dur- ing this dry period constitute from 24 percent to 66 percent of the na- tural river flow. Similarly, in the Potomac River, consumptive losses are from 40 percent to 70 percent and in the James River 11 percent to 36 per- cent of the natural river low flow. During periods of higher flows, the consumptive uses are only a small fraction of the total river flow. On the average, consumptive uses consti- tute 4 percent of the 39,000 cfs average flow in the Susquehanna Riv- er, 6 percent of the 7,900 cfs aver- age flow in the James River, 7 per- cent of the 11,000 cfs average flow in the Potomac River and 5 percent of the 76,600 cfs average contribution of fresh water by all tributaries to the bay. There is widespread concern relative to the potential consequen- ces of these reduced freshwater in- flows. The Susquehanna River Basin Report Coordinating Committee in its 1969 report identified this as a high priority study item and both the Susquehanna River Basin Commission and the State of Maryland have written to the Baltimore District Engineer requesting that the Corps of Engineers perform studies addressing the problem. In addition, the Chesa- peake Bay Study Advisory Group, 117 Table 1. Chesapeake Bay low freshwater inflow study. Susquehanna River weekly average low freshwater inflows with and without consumptive losses (cubic feet per second) . Week Ending Recorded Flow Consumptive Loss (2020) Reduced Flow Percent Reduction 5 Aug 64 12 Aug 64 19 Aug 64 26 Aug 64 2 Sep 64 9 Sep 64 16 Sep 64 23 Sep 64 30 Sep 64 7 Oct 64 14 Oct 64 21 Oct 64 28 Oct 64 5087 7155 4900 3968 3955 3182 2613 2415 2466 3980 3182 3462 3223 1752 1752 1752 1752 1632 1632 1632 1632 1632 1600 1600 1600 1600 3335 5403 3148 2216 2323 1550 981 783 834 2380 1582 1862 1623 34 24 36 44 41 51 62 68 66 40 50 46 50 118 Steering Committee, and Citizens Advisory Committee have identified reduced inflows as one of the more important problems facing Chesapeake Bay. Thus, the Chesapeake Bay Low Freshwater Inflow Study was conceived in an atmosphere of almost universal concern over the potential economic, social and environmental impacts of reduced freshwater inflows. STUDY OBJECTIVES Three objectives have been es- tablished for the Corps of Engineers' Low Freshwater Inflow Study as fol- lows : which have historically been respons- ible for certain features of water resource development. We have, therefore, established the study organization shown in Figure 2. This organization was conceived under the basic premise that the study would be a coordinated partnership among Fede- ral and state agencies, interested educational institutions, and the public. Each agency is charged with exercising leadership in those disciplines in which it has special competence. For instance, the Annapolis field office of the Fish and Wildlife Service has the lead role in those aspects of the Low Freshwater Inflow Study that are related to environmental concerns. 1. To provide a better under- standing of the relationship between the salinities in the Chesapeake Bay and the freshwater inflows contrib- uted by its tributaries; 2. To define the environ- mental, social and economic impacts of both short- and long-term reduc- tions in freshwater inflow; and 3. To recommend the minimum flow or schedule of flows that should be maintained in the major bay tribu- taries in order to assure the in- tegrity of Chesapeake Bay. STUDY ORGANIZATION The Low Freshwater Inflow Study as well as the other elements of the Corps' Chesapeake Bay Study Program are of such a complexity and magni- tude, and involve so many varied disciplines that no single entity could be expected to have the re- quisite personnel, equipment and technical know-how necessary to ac- complish the many special studies that are required. Such expertise does exist among the many agencies To facilitate the realization of these ends, an Advisory Group was established. The major purpose of this Advisory Group is to assist the district engineer in establishing broad guidance and providing general direction under which all parti- cipants will work. The group takes into consideration the views and needs of those involved in the study and advises the district engineer on establishing policy regarding both the execution of tasks and the reso- lution of conflicts that may arise. The Steering Committee consists of scientists who are knowledgeable about Chesapeake Bay. This committee is responsible for reviewing the work of other groups and bringing to their attention any pertinent advances in the art of water resource development or the environmental sciences. This committee also formulates plans for scientific activities that are a necessary adjunct to this study. For example, the Steering Committee has provided the primary guidance for conducting the Low Freshwater Inflow Study, particularly those aspects re- lated to biological evaluations and tests on the Hydraulic Model of Ches- apeake Bay. 119 Figure 2 Organization — Chesapeake Bay Study Baltimore District Corps Of Engineers Advisory Group Steering Committee, Liaison, & Basic Research Agriculture Navy Corps Of Engineers Pennsylvania Atomic Energy Commission Smithsonian Institution Atomic Energy Commission Virginia Commerce Transportation Interior Federal Power Commission Delaware Health, Education. & Welfare District Ot Columbia National Science Foundation Smithsonian Institution Housing & Urban Development Maryland Commerce Interior Pennsylvania Delaware National Science Foundation Virginia Distnct Of Columbia Environmental Protection Agency Maryland Water Q uality & Flood C ontroi. Economic Projection Suppy, Waste Navigation, Erosion, Recreation Task Fish & Wildlife Task Group Treatment, Noxious Weeds Task Group Fisheries Task Group Group Coordination Group Commerce Environmental Protection Corps Of Engineers Intenor Intenor Agriculture Agency Agnculture Agnculture Corps Of Engineers Housing & Urban Agriculture Commerce Health, Education, Commerce Development Intenor Atomic Energy Commission Federal Power Commision & Welfare Navy Environmental Protection Agency Transportation Corps Of Engineers Environmental Protection Agency Federal Power Commission Health, Education. & Welfare Navy Health. Education, & Welfare Intenor Transportation Transportation Corps Of Engineers Environmental Protection Agency Delaware District Of Columbia Maryland Delaware Transportation Environmental Protection Delaware Pennsylvania Distnct Of Columbia Pennsylvania Virginia Corps Of Engineers Delaware District Of Columbia Maryland Pennsylvania Virginia Agency Delaware District Of Columbia Maryland Distnct Of Columbia Maryland Pennsylvania Virginia Virginia 120 The task groups are functioning as basic work groups in each of the five study areas. The individual task groups are composed of those agencies interested in the study problems assigned to it. Through this mechanism it is intended that constant liaison, work review, and requisite agency interaction is main- tained. A public participation program has also been established so that the views of the general public are in- corporated in the study process. A major component of this program is a Citizens Advisory Committee composed of members of the Citizens Program for Chesapeake Bay--an umbrella organization consisting of environ- mental, industrial, and political groups . STUDY METHODOLOGY In the Low Freshwater Inflow Study, primary efforts have been pur- posely focused on those parameters directly related to salinity because it was apparent early in the work that there is not a sufficient data base available to address many of the other factors which may be affected by changes in freshwater inflows. One of these is the problem of de- fining the mechanisms of biotic transport--a phenomenon whereby many of the non-swimming species are transported to their place in the estuary by currents. There is, how- ever, only a minimal knowledge of the current patterns of Chesapeake Bay. Even more serious, there is little understanding of how species movement relates to these current patterns. Other areas where the data base is apparently inadequate include the interaction of individual species and families of species, and the rela- tionship of freshwater inflows to sediment patterns, the nutrient budget, and temperature. Further research is needed in all these areas before there will be a sufficient data base available to fully address them in management oriented studies such as the Corps of Engineers' Low Freshwater Inflow Study. This is not to imply that these factors are being ignored, rather, they are being ad- dressed only in the detail that is consistent with the available data base. Work on the Low Freshwater In- flow Study is progressing in accord- ance with the accepted interactive planning process. This process in- volves problem identification; the assessment of social, economic, and environmental impacts; the arraying of alternative solutions; and the formulation of a plan. As previously indicated the primary focus of this work is on the relationship between freshwater inflows and salinities. One of the reasons this type of study has rarely been done in the past, however, has been the difficulty of accurately determining this rela- tionship because it can be accom- plished only with the aid of tools which can simulate or reproduce the complex three-dimensional estuarine system. The Chesapeake Bay Model does have this capability. In fact, the only other way sufficient data to conduct this study could be made available would be to collect them from the real Chesapeake Bay; a nearly impossible undertaking. To do this it would be necessary to wait for a drought; and who knows when this will occur? During the drought, the data would have to be collected almost continuously over at least a three-year period. This costly venture would require hundreds of people, boats, and equipment. And finally, there is no way presently 121 available to simulate in the bay the depression in river flows associated with consumptive water use. On the other hand, a drought or depressed freshwater inflows can be simulated at any time on the Chesa- peake Bay Model as can nearly any other hydrologic event. The fact that the model is built to a hori- zontal scale of 1 to 1000 and a vertical scale of 1 to 100 means that Chesapeake Bay has been reduced to less than eight acres, a manageable size which allows for the ready, relatively inexpensive collection of data. And with a time scale of 1 to 100, one year's data can be collected in a little over 3.5 days. Pictures of the model and the 14-acre shelter housing it are shown in Figures 3 and 4. HYDRAULIC MODEL TESTS In order to accomplish the ob- jectives of the Chesapeake Bay Fresh- water Inflow Study, it will be neces- sary to conduct a series of three tests on the hydraulic model, i.e., a problem-identification test, a sen- sitivity test, and a plan formulation test. Both the problem-identifica- tion and the sensitivity tests focus on identifying the magnitude of the problem and determining the rela- tionship between freshwater inflows and salinities. The plan formulation test is oriented to the formulation of minimum acceptable freshwater in- flows from each of the major bay tributaries. In each test, a re- presentative variable long-term average tide and a weekly hydrograph of freshwater inflows will be used. Both of these will be controlled by a computer. The purpose of the problem iden- tification test is to determine bay- wide salinity levels during a drought of record under both natural flow conditions and flow conditions re- duced by projected consumptive loss- es. This test will be done in two parts. The first, or base part, will focus on establishing the salinity structure of the bay during natural drought conditions and determining the amount of time it takes to re- cover from a drought to a condition of dynamic normality. This will be done by simulating on the model the three low flow years of the worst drought of record (1964, 1965, and 1966) followed by two years of aver- age freshwater inflow conditions. The second, or future part of the test, will be concerned with the magnitude of change in salinities which would be caused by high consumptive uses of water during a severe drought. As in the first part, a five-year hydro- graph of freshwater inflows will be simulated in the model. In this case, however, the natural inflows during the three drought and two average inflow years will be reduced by an amount equal to the uncon- strained consumptive losses predict- ed to occur in the year 2020. A com- parison of the data from the base and future parts of the test will yield the changes in the salinity regime resulting from decreased freshwater inflows. The data from both of these parts will be used as the basis for specifically defining existing and potential problems as they relate to both short- and long-term reductions in freshwater inflows and in ascer- taining the environmental, social, and economic consequences of low freshwater inflows. They will also be used as a basis for formulating minimum freshwater inflow criteria. 122 Figure 3 Chesapeake Bay Model Shelter F/'gure 4 Chesapeake Bay Model 123 This will be a multi-disciplinary effort involving economists, tidal hydrologists , social scientists, en- gineers, and biologists. These data will also be important in estab- lishing the relationship between freshwater inflows and salinities in terms of both the effects of various quantities of inflow and the time it takes for salinity levels to respond to changes in flow (reaction time). It would be difficult, however, to determine from these data the role of each tributary in controlling salinity levels, especially in a geographic perspective. To accom- plish this it will be necessary to conduct another series of tests on the model (sensitivity tests). In these sensitivity tests, each major tributary to Chesapeake Bay will be analyzed separately. A one-year hydrograph of the natural freshwater inflows which occurred during the drought of record will be simulated in all tributary rivers except one. In that river, the freshwater inflows will be depressed by anticipated year 2020 consumptive losses. This will be repeated until all major tribu- taries have been addressed. The third, or plan formulation series of low flow model tests, will be oriented to formulating a schedule of freshwater inflows for each major tributary which will allow for a healthy biota consistent with social and economic feasibility. The tests to be run will be based on the model tests, impact analyses, and a screen- ing of alternative freshwater inflow levels . BIOTA ASSESSMENT A methodology for assessing the impacts of reduced freshwater inflows on the biota of Chesapeake Bay has been developed and is being applied by the consulting firm of Western Eco-Systems Technology (WESTECH) under contract with the Corps of Engineers. In view of the importance of this work, the fact that there is little precedence for it, and the fact that WESTECH is working right at the state-of-the-art, the Chesapeake Bay Study Steering Committee and the Fish and Wildlife Service are inti- mately involved providing guidance and review of the work as it prog- ressses . Recognizing that it is impossi- ble to address all of the over 2,700 species that live in Chesapeake Bay, WESTECH developed, through an in- tensive screening process, a list of over 55 study species. The present known and potential distribution of these species, average salinity, and known substrate were then plotted on maps. These maps will be the basic tool used in the evaluation of the primary impacts of flow changes. Additional maps will be prepared reflecting each set of hydraulic model salinity data. A determina- tion will then be made of the varia- tions in available habitat caused by salinity changes. These habitat variations will be used in assessing the primary biological impacts of flow reductions. The next step will be the as- sessment of secondary impacts. This is an extremely difficult task be- cause it involves not only the rela- tionship between salinity and orga- nisms, but the interrelationship among species and families of spe- cies. Because a sufficient data base is not available to address these in any great detail, the secondary im- pact assessment methodology consists of a systems analysis based on a conceptual model and the best avail- able scientific judgments. 124 PLAN FORMULATION Social and economic factors also play an important part in the Chesa- peake Bay Low Freshwater Inflow Study. An inventory has been made of those economic and social activities which might be affected by changes in freshwater inflows. Examples of these are the withdrawal of water for municipal and industrial use and a potential change in finfish and shellfish harvest which would affect the seafood harvesting and processing sectors. Intensive analyses will be performed relative to all such acti- vities to establish the social, economic, and environmental impact of reduced freshwater inflows. In conjunction with the environ- mental, social, and economic assess- ments a preliminary institutional analysis will be done to survey the existing political, legal and finan- cial structure as it relates to pos- sible implementation of flow cri- teria. This analysis will focus on the entire Chesapeake Bay Basin. The next stage of the program will be oriented to formulating and evaluating those alternate flows from the major tributaries which have the potential for alleviating any prob- lems which may be identified. Up- stream measures to achieve these flows will also be identified. Such measures may include reservoir stor- age to augment low flows in the river, conservation measures which produce reductions in consumptive use of water, and policy changes regard- ing future growth in water-consump- tion activities. The biological, economic, so- cial, and institutional impacts of the alternative flows and measures to achieve these flows will be assessed and evaluated, although the upstream analysis will probably be in consid- erably less detail than the assess- ment and evaluation of impacts in the bay proper. Based on these analyses, those alternative flows most accept- able under the guidelines provided through the Water Resources Council in its Principles and Standards will be identified and tested during the plan low flow model test. The data from the biological, social, economic and institutional analysis and the final model test will be used in the selection of the schedule of flows to be recommended for each of the major tributaries of the Chesapeake Bay. While a recommended flow schedule will be provided for each of the major tributaries, no recommenda- tion will be made as to the specific upstream measures that should be undertaken to meet the recommended flows. It is anticipated that recom- mendations for further study of spe- cific upstream alternatives will be included in the final report. DISCUSSION Question: Would you care to comment on any other uses that the model over on the eastern shore of the Chesapeake Bay is going to be put to in the near future? Answer: I'll answer this question in the context of how the Corps of Engineers is using the Hy- draulic Model in its studies of Chesapeake Bay. We have formulated a four-year program of tests on the model. The largest component of this program is the Low Freshwater Inflow Test that I have just described. But, we are also looking at other problems that are related to fresh- water inflow. One of these is the 125 problem of supplying water to the Washington Metropolitan Area. This area is already water short, and should we have another drought, there could be problems. My co-workers at the Baltimore District are currently conducting a study oriented to solving this water supply problem. One thing is clear. There are a lot of alternatives. An important one of these is a proposal to use Potomac Estuary at Washington as a supplemental water supply source. There are, however, some questions regarding this proposal. First, although the water at the lo- cation where an intake is being con- sidered is normally fresh, the salt wedge intruded to within several miles of it during the last drought. If large quantities of water are withdrawn during one of these droughts, will the salt wedge move far enough upstream to contaminate the water at the intakes? Second, the major wastewater treatment plant for Washington is located about 10 miles downstream from the proposed water supply intake. Will withdraw- ing water reverse the flow of the estuary sufficiently to cause the wastewater plume to reach these intakes? And third, will withdraw- ing water during the droughts result in sufficient change in the environ- ment to threaten the integrity of the ecosystem? In order to assist in answering these questions, we are going to con- duct a test on the Chesapeake Bay Model. This test will be in 16 parts. In each part we will simulate a constant flow into the estuary of zero, 250, 500, or 900 mgd, combined with a water supply withdrawal of zero, 100, or 200 mgd. Under each condition, the level of pollution and the salt content of the water will be determined. These data will be input to the social, economic, and environmental analyses that are nec- essary to determine the feasibility of using the estuary as a supplemen- tal water supply source for the Washington Metropolitan Area. The water of the Potomac Estuary is already rather polluted and it is anticipated that advanced treatment methods will be required to make it potable. In order to develop these methods, Congress has directed that a pilot treatment plant be construct- ed. We have already started work on this plant and anticipate that it will be completed next year. At that time, a one-year research program will be instituted. Last October, the State of Maryland asked us to conduct for them a short test on the Nanticoke River. A large quantity of toxic materials were stored at Sharptown, Maryland, and the state was concerned that they may somehow enter the waterway. Through use of the model, we were able to provide the state with the data needed relative to the fate of any toxic materials that may enter the Nanticoke River. Another test which will be done for the State of Maryland is related to the dispersion of the thermal plume from power plants. In this test we will simulate the heated discharge from an existing plant and a proposed one. The thermal plume will be moni- tored over a one-year period to ascertain its rate and extent of dis- persion. This test will also di- rectly benefit the Corps of Engineers as the State has already collected some field data, and we can use these data to verify that the model ac- curately simulates dispersion. The High Freshwater Inflow Test is one of our more important tests. The objective of this test is to 126 ascertain the impacts on Chesapeake Bay of large influxes of freshwater similar to those which occurred dur- ing Tropical Storm Agnes. We intend to simulate on the model three events of this type. Data collection ef- forts will be oriented to monitoring salinity levels and ascertaining how long the bay takes to return to a state of dynamic normality. These data will be used in assessing the social, economic, and environmental impact of high freshwater inflows. The latest test in our program is the Tidal Flooding Test. Today, the people of Chesapeake Bay area feel rather secure, as the last large flood was in 1933. Since that time, there has been much development in the flood plain, and if another storm occurred, there could be wide- spread damage. But, the flood plain of Chesapeake Bay and its tributaries is not that well defined. Our ob- jective is to use the hydraulic model in conjunction with a numerical model to provide a better definition of flood frequency. In this case, our primary tool will be the numerical model. Data from the hydraulic model will be used to assist in calibrating and verifying the numeri- cal model. I might add that con- junctive use of models is becoming increasingly important in addressing hydrodynamic phenomena. There is no question that better answers can be obtained if the numerical model and the hydraulic model are used so that their strengths are accentuated and their weaknesses minimized. REFERENCES U.S. Army Engineer District, Balti- more. Chesapeake Bay Plan of Study, June 1970. U.S. Army Engineer District, Balti- more. Chesapeake Bay existing condition report; 1973. Avail- able from NTIS, Springfield, VA; AD-A005500 thru AD-A005506. U.S. Army Engineer District, Balti- more. Chesapeake Bay future con- dition report; 1977. Available from NTIS, Springfield, VA; AD- A052482. U.S. Army Engineer District, Balti- more. Chesapeake Bay study re- vised plan of study; October 1978. Western Eco-Systems Technology. Ches- apeake Bay low flow study; Biota Assessment; 1980. 127 ASPECTS OF IMPACT ASSESSMENT OF LOW FRESHWATER INFLOWS TO CHESAPEAKE BAY G. Bradford Shea, G.B. Mackiernan, L. Chris Athanas, and D.F. Bleil Western Ecosystems Technology, Laurel, Maryland ABSTRACT Modification of the Chesapeake Bay hydrologic environment has oc- curred over the past several decades, and is expected to continue at least until the end of the century. An attempt to assess the impact of low freshwater inflows (due to drought and consumptive losses) upon the Chesapeake Bay biota is currently underway. Some of the tools being used in this assessment are 1) dis- tribution, tolerance, and life his- tory studies of selected estuarine species, 2) hydraulic modeling of the bay's salinity and circulation re- gimes, and (3) computer simulation of representative segments of the ecosystem. The uses and limitations of each are discussed. Critical life history stages, habitat and food requirements, and tolerance to physical stress have been used to select representative study species for evaluation of effects of reduced freshwater flows. This approach is limited by the in- ability of species-by-species anal- ysis to deal adequately with the interrelationships between estuarine organisms. Information on community structure and trophic relationships has been used to develop a conceptual model of major energy flows within the Chesapeake Bay ecosystem. A com- puter simulation model will be used to provide insight into the effects of low flow, and the propagation of these effects throughout the eco- system. The results of this study will aid managers in planning con- sumptive-use patterns of freshwater flows into the estuary. INTRODUCTION The U.S. Army Corps of Engineers has, among its responsibilities, that of setting low flows on many Federal water resource projects on regulated rivers. In addition, in 1965, Con- gress authorized the Corps, under Section 312 of the River and Harbor Act to "make a complete investigation and study of water util- ization and control of the Chesapeake Bay Basin." This authorization included authority to develop tools to study altered flow conditions including a hydraulic model. The investigation authorized by Congress led to, among many other products, a study of low flows and their impact upon the biota of the Chesapeake Bay and its tributaries. This "Biota Assessment" was under- taken beginning in 1979 by Western Eco-Systems Technology (WESTECH) un- der the auspices of the Corps of Engineers and is still in progress. The study area extends from the bay mouth to the head of the tide, as shown in Figure 1 . 128 Source- Md. Geologic Survey, 1970 Figure 1. Head Of The Tide In Chesapeake Bay Tributaries 129 The Biota Assessment is divided into two phases. The purpose of Phase I was to establish base con- ditions and develop methodologies with which to identify effects of low flow conditions on biological organ- isms. Phase II, which will begin during the autumn of 1980, will use these methodologies, together with salinity data from the Corps' hydraulic model to make assessments of biological effects during a drought comparable to that which occurred dur- ing the mid 1960's, a period of increased consumptive water loss due to increases in population and water use in the bay area (as pre- dicted for the year 2020) , and a combination of drought and consumptive water loss (i.e. a drought occurring in the year 2020). The methods developed to analyze these scenarios are explained in the remainder of this paper. DEVELOPMENT OF METHODOLOGY A given factor at the onset of the Biota Assessment of the Chesapeake Bay Low Flow Project was that it be based on the volu- minous existing research on the Chesapeake Bay. Research con- ducted in the assessment was to be aimed toward synthesis and classi- fication of this information and was to derive theoretical methods to increase its usefulness. No new field research was conducted. LITERATURE SEARCH The initial tasks included a search and compilation of the litera- ture and establishment of working contact with bay researchers in a wide variety of fields and insti- tutions. The literature search task consisted of a "keyword" computer search of major sources, coupled to a manual search of major journals and the "grey literature," including technical publications of academic institutions and government agencies. Establish Baselines The methodology developed during Phase I involved a multiple approach to assessing low flow impacts. This multiple approach included (1) set- ting a baseline, (2) selecting study species, and (3) defining tolerances for and interactions between those species. These multiple approaches are discussed in this and the fol- lowing two subsections. The word "impact" presupposes a change that can be measured. Such measurement requires establishment of base conditions and delineation of change from that base. For an estu- ary as complex as Chesapeake Bay, knowledge of the state of the system at a given time is severely limited by the difficulty of doing simul- taneous studies. Rather, even research on large projects is typically concentrated in a parti- cular tributary or bay-segment. Therefore, baselines were selected from particular time periods best suited to the data. Physical, chemical and bio- logical baseline periods were select- ed in order to set base conditions from which to draw data compilations and to serve as a basis for mapping. The physical baseline focused on sa- linity. The base period selected was 130 Water Year 1960. Data were drawn from the Chesapeake Bay Institute Salinity Atlas (Stroup and Lynn 1963). Setting the chemical baseline mostly involved nutrients. Data were drawn from USGS files and from large scale data banks from studies con- ducted at various periods during the 1960's and 1970's. Biological data were similarly selected from a com- posite of studies during the 20-year period, 1960 to 1980. An attempt was made to put this data into a context which defines the "health and pro- ductivity of the estuary;" however, after a discussion with other bay researchers, it became clear that these concepts could be defined only relative to the baseline and not in an absolute sense. SPECIES SELECTION Characterization of biological impact in an estuarine system must involve species at all major trophic levels. However, the Chesapeake Bay is estimated to contain over 2,500 species. Clearly some limitation is necessary. A multi-step process was em- ployed to select species which are both important to the Chesapeake Bay ecosystem and/or are sensitive to low flow effects (Figure 2). Some organ- isms which are not sensitive to flow changes are too integral a part of the ecological system not to be con- sidered. From the immense universe of bay species, a list of 167 candidate study species was selected by assess- ing from the literature the relative vulnerability of any portion of the species' life history to habitat alteration and other criteria. These were then reviewed by the anchor team and Corps Steering Committee. A second screening reduced the list to 81 species, based on availability of detailed literature on stress toler- ance and ecosystem importance. The final screening to 57 species was conducted through use of comparison matrices which compiled the sensi- tivity of each species or any vul- nerable life stage to specific habi- tat alterations (i.e. salinity, food, circulation, and substrate). The amount and quality of avail- able data, the economic or social value, and the competitive and pre- datory or trophic relationships were compiled from available literature and discussions with researchers. A weighted ranking system was then employed to identify the most important, most sensitive and best researched of the study species. These species were then used for determination of tolerances, distri- bution mapping, and conceptual and simulation modeling. Chesapeake Bay, although a relatively shallow estuary, supports a large variety of species in various habitats. These habitats range from deepwater pelagic zones to beds of submerged or emergent aquatic vege- tation (Figure 3). In order to explore the relationships by which organism distributions are controlled by environmental parameters, a class- ification for habitat types was de- fined. There have been numerous at- tempts at estuarine habitat classi- fication (Cowardin et al. 1977) for various purposes. Since the low flow study is mainly focused on salinity, this was chosen as the major variable in the habitat classification system used. We employed a minor modifi- cation of the Venice System (Symposium on the Classification of Brackish Waters 1959) in which the mesohaline category was divided into upper-and-lower mesohaline as follows (Figure 4): 131 Limnetic (tidal fresh water) 0.0 - 0.5 o/oo Oligohaline 0.5 - 5.0 o/oo Lower Mesohaline 5.0 -10.0 o/oo Upper Mesohaline 10.0 -18.0 o/oo Polyhaline Euhaline 18.0-25.0 o/oo 30.0 °/oo In addition, we have defined cate- gories of substrate, depth, season- ality (as related to temperature) and modifications of habitat by other organisms. These categories have been placed on base maps from known Chesapeake Bay data bases. Appro- priate combinations of categories into the requirements of a particular organism are then used to define that organism's "potential habitat," wher- ever sampling data are insufficient to define a "known habitat," or area where the organism has been previ- ously identified (see Figure 5). These habitat systems then were used to form the framework for inter- preting information in the literature on salinity tolerances or require- ments for salinity, depth, substrate, etc. Salinity tolerances, for in- stance, were derived for each orga- nism and the appropriate Venice cate- gory determined. Organism distribu- tion was defined by a combination of known locations with "potential habitat" derived from the Venice categories and the other param- eters discussed above. Locations of the salinity contours necessary were taken from seasonal data from the 1960 water year, largely from the Chesapeake Bay Salinity Atlas (Stroup and Lynn 1963). These have been plotted on 1:250,000 scale maps of Chesapeake Bay, as have categories of substrate, depth, and other habitat var- iables. Using these base maps, organism distributions have been mapped on 1:250,000 scale mylar overlays for the 57 study species. Examples of such maps are shown in Figures 6 and 7 . ECOLOGICAL RELATIONSHIPS Low flows cause direct or primary effects on species through physiological responses due to changes in salinity, nutrients, water quality and similar factors. These effects are generally either immed- iate or occur over a short period of time (i.e. a few days or weeks). In response, species may increase or decline in population, become extinct in the area, or migrate to suitable habitat in other parts of the estu- ary, if such habitat exists. These shifts in abundance or distribution imply a new interplay of trophic relationships, which we will term here indirect or secondary effects. The time span of such effects may range from several days to several years, or permanently in cases where a new ecological equilibrium is established. In order to investigate these species relationships, con- ceptual and mathematical models were developed for Chesapeake Bay. The approach to modeling used in the project is shown in Figure 8. Data from the scientific literature and related sources served as input to define physiological tolerances and constraints. Predator-prey inter- actions were defined and basic trophic interactions were charted for interrelated groups (i.e. phyto- plankton-zooplankton, etc.). These were then integrated and formed the basis for a conceptual model illus- trating the major trophic interac- tions and nutrient flows . The sum- mary version of this conceptual model is shown in Figure 9, using H.T. Odum's energy language to illustrate 132 x^ V s econd Pre liminory Species List 81 species <■ V Se m i f i n a I Selection 57 species Apply candidate criteria Availability of data and Ecosystem importance Weighted Screening Criteria Matrix Anchor Team Review Figure 2 SCREENING PROCESS FOR SELECTION OF STUDY SPECIES 133 134 FALL SALINITY ZONES In the CHESAPEAKE BAY Venice System Figure 4 RESH ® 0-.55S.* LINE ®.5-5%o ALINE @ 5-10%. HIGH MESOHALINE ® 10-18 %„ LOW POLYHALINE © 18-25%. * »»«rt or IALT/IOOO 0* »*Tl« 135 Substrate Boundary Potential Habitat based on Salinity and substrate Figure 5 KNOWN AND POTENTIAL HABITAT OF HYPOTHETICAL BENTHIC ORGANISM BASED ON STATION DATA, SUBSTRATE AND SALINITY 136 Sources1 Burrell, 1972 Goodwyn, 1970 Grant & Olney, 1979 Heinle ,1969 Jocobs, 1978 Rupp, 1969 Sage 8. Olson, 1976 See Text 10 =3 Figure 6 CHESAPEAKE BAY ^/Iflj Acartia ciausi - COPEPOD SPRING DISTRIBUTION Average Adult Concentration '// Generally less than 5000m5 Generally more than 5000 m5 __ Upstream Boundary of Potential Hobitat AV\ Incomplete Knowledge MILES 137 Sources Mansueti & Ritchie S Koo, 1973 Scott 8 Boon , I 973 CHESAPEAKE BAY Morone s axe til is -Striped Bass DISTRIBUTION Known and potential Habitat ,".-'"' Spawning Area- Eggs a Lorvoe Juveniles ADULT a SUBADULT '// Summer Winter 138 a ■9 «■ >s O O ^ C c a 4 o — c *■ o • < CO o CO O o — > < o _J < > ! ? o o o O •"fs^ § • c > 3 E o u O O ^ /\ Q UJ N cc UJ i- a. S o o a o to o D c o • o o — o ° * 5 II • •9 *— C D O ^ C O o • CO — o < _l Q UJ N cr UJ Q. O c — o o — o •. «_ » ° c ; e • • £ • 2 £■ f uj *■ O > o CO o o o I- c a> E c o c UJ -I UJ o a o o o f ._ » * ° 2 o _ a> — — «- >» o o — o O o CO o D. CO • \ , > -J 2 ». f UJ UJ _ o 2 Z 2 o o •y Tv _ • O a, Q u = CO CO X! 5 > _l a> LU •S * Q 9 — o a> u- 2 £ u. 1 _l LU < > D cr 3 _ 1- LU U. Co 0. > ent reli Ih.e LU O o w - C — * O z o 3 o-o O ■ 140 producers, consumers and storage compartments . A conceptual model of this scope is complex, even in this summary form. Perturbation of the system by a stress, such as low flow, induces many concurrent changes in com- partments, functions of organisms and trophic flows. The human mind has difficulty dealing with such simul- taneous changes and their ramifica- tions. Computers form a powerful tool for dealing with such systems. Therefore a simulation program (designated Chesapeake Bay Ecosystem Model -CBEM) was created to assist in dealing with secondary effects. This model supplements the conceptual model and provides a tool to analyze the sensitivity of particular spe- cies or compartments to low flow ef- fects . CBEM has been initially defined for the lower mesohaline Venice zones, using data from the Patuxent River, one of the western shore tributaries of the bay. Under average flow conditions, the species and compartments utilized are shown in Figure 10. The system includes phytoplankton as the major producers, grazed by two competitive species of copepod zooplankters . These are grazed in turn by ctenophores during particular time periods. Other feed- ers include benthic grazers (oys- ters), juvenile fish and menhaden. The model is based on sets of quasi-linear differential equations which are periodically corrected to compensate for non-linear behavior in the ecosystem. The model operates by calculating daily productivities and abundances based on changing physical and chemical conditions which can be either input as data or calculated as the program evolves in time. Typical simulated timeframes range from 1 to 5 years for a run. Thus the effects of a low flow period can be tracked for long-term biological changes which occur after the system has returned to a physical or chemical equilibrium. The model was calibrated with data on known responses and growth rates of organisms, predominantly in the Chesapeake Bay; however, data from other estuaries were used where Chesapeake data did not exist. Tests of the model's validity under average flow conditions were then made, using existing historical data from the Patuxent River, which had not been used to create or calibrate the model. An example appears in Figure 11 for phytoplankton abundance. The figure shows that, in general, simu- lated phytoplankton abundance agrees well with observed data, although there is a fall bloom in the simu- lation which is not typically mani- fested in the data. Knowledge of such discrepancies prompt investi- gation of biological properties of the ecosystem which might supress or mask such a plankton bloom. The effects of predation, and the usefulness of CBEM as a tool to study predation effects are illus- trated in Figure 12. The changes may differentially affect several other species in the food web, and often are manifested quite differently at times throughout the year as popu- lation abundances, growth potential, and feeding behavior are altered. The main usefulness of both conceptual and mathematical models is to study effects of low flows, parti- cularly those associated with sa- linity changes. Average annual stream flow into Chesapeake Bay has historically ranged from lows near 50,000 cfs to highs near 150,000 cfs, a dramatic range of values, parti- cularly as it impacts salinity and water quality. Figure 13 shows two 141 oc z LU o 1 1- a. < UJ a 2 3 o O 2 2 o CO 142 24,000 -■ 18,000 -• E o O 12,000 -- 6,000 -- 0 0 MAX volvet X MIN valves WESTECH BEM Simulation Mont hs Figure 11 Sources of observed data: ANSP.unpub., 1975-79 ;Flemer et al, 1970 ; Stross and stottlemyer,l965 SIMULATED AND OBSERVED PHYTOPL ANKTON ABUNDANCE 143 1,00 0 -T 800 -• 600-- 400 -- 200 -- A. tonsa MODIFIED SIMULATION ^T ^ Acortio tonsa Simulation (Standard) Figure 12 SIMULATED ABUNDANCE OF Acartia tonsa AND A. c/ausi WHEN Mnemiopsis IS PREDATED AT A DAILY RATE OF 10% (Day 246-365) 144 FlfM »rv U iV1^ o a ^%>v s i CD UJ < UJ CO o> UJ "5 t- O 1- o> a: h E UJ z a> St- o a> >■ o ffi CD UJ < UJ 0. < to UJ X o z _J < CO o z 1- co < cr Z O o 3 O ro to ff> c c c a to to to ■o 5 o to 145 years of contrasting salinity regimes in the upper bay. The species which inhabit the bay are divided into groups with certain tolerances which govern their distribution (Figure 14), ranging from those limited to marine waters, to those limited to fresh water, either for their entire lifetimes or for critical stages such as spawning. The conceptual or CBEM models can be used as tools to study the effects of new organisms introduced into a given segment of the bay or tributary as salinity regimes change. For instance, CBEM has been run under conditions of higher salinity simu- lating low flow conditions in the Patuxent. The simulations involved the introduction of predators such as the sea nettle, which are not normally present under average flow conditions. Other factors such as respiration changes, abundance changes, etc. were also altered to conform to the expected changes due to low flows. The biological inter- actions which were then observed were checked against data from higher sa- linity zones and some data from a pre- vious drought period and shown to be within a reasonable range of values for such conditions. Obviously, such ecological modeling has many limitations. Its usefulness is limited by the validity and completeness of the input data base (which for many estuaries is not particularly good) . It is also limited by the number of simplifying assumptions that must be made. How- ever, we believe CBEM provides an effective tool for better under- standing the complex dynamic inter- actions which occur under estuarine conditions . APPLICATION OF METHODOLOGIES In Phase II of the Biota Assess- ment, the tools and methods developed during Phase I will be applied to assessing impact of three low flow scenarios based on Corps hydraulic model salinity data. Organism habi- tats, defined in Phase I for the 57 study species will be analyzed for changes under each low flow scenario. This will be quantified in terms of "impact ratios" which are measures of the change in either known or po- tential habitat due to salinity alterations. These ratios may be either positive or negative for a particular organism and represent a range rather than a single number, to reflect the inherent inaccuracies in data and gaps in current scientific knowledge of the estuary. These "impact ratios" will measure the direct effects of low flow conditions on individual species. Indirect or secondary effects which result from species inter- actions will be expressed quantita- tively or qualitatively (as possible and appropriate) utilizing conceptual or simulation modeling as described in the previous section. Quanti- fication of these secondary effects is difficult, particularly in areas where the data base is weak, such as tributaries on the eastern shore of the bay. SUMMARY Phase I of the Biota Assess- ment, a portion of the Chesapeake Bay Low Flow Study, has developed a set of tools and methods with which to assess impacts of low flows. These include 1 . Definitions of habitats using uniform variables on a bay- wide basis. 2. Selection of a set of study species which represent the 146 Jl <^ n^ — x o t-u- o sm ^ ■■ 0UJ o2. "~ _J o? r- < CO W. CM UJ z _l < X o w ui S CM CO UI z < X -J o Q. w UJ UI UI H CO UJ 2 ui -J z z _l UI z 2 CO J Z — < = < X < 3 O X X X < X H UJ o < > 2 >- X D. 5s X 3 X O 3 0- CO H UI UJ Q- (/> O z w X < 3 2 ui Q UI UI (- x< UJ o < cr > i- co UJ z or < 3 H- CO UI UJ C9 i— i UI © u. 0> o CA 0> O CD 0 < Z CO CO < or o u. o z o F= < M 147 main components of the ecological dynamics of the bay. 3. Definition of physical and chemical tolerances and distri- bution patterns for these organisms (distributions have been produced in a large size map atlas of the entire bay at 1:250,000 scale). 4. Conceptual and simulation models of bay organisms. These tools will then form the basis for analysis of Corps hydraulic model data representing various low flow conditions during Phase II of the Biota Assessment. DISCUSSION Question: (to Dr. Shea) I'm a little curious about this species basis approach to looking at the slough problem in the Chesapeake. You have identified 57 species you've been working with in terms of their salinity tolerance and how they might respond. I wonder, of these 57 species, how many, for example, were plankton or micro zoo- plankton or bacteria? Answer: What happens with that kind of approach—because of what people are conscious of--when you start going at it species by species they will start pointing out things they like to catch or eat or see in the bay. That's where we have species-related data on things like striped bass. Whereas what makes any estuarine system go or operate are things which we can't even recognize as a species. We don't have any data for them. Nobody eats or cares about them on an organism level. REFERENCES Boesch, H. F. The ecology of the marine cladocera of lower Chesa- peake Bay. University of Vir- ginia; 1977 101 p. Dissertation. Burrell 1972; Goodwin 1970; Grant & Olney 1979; Heinle 1969, Jacobs, 1978; Rupp 1969; Sage & Olson 1976. Cited in: Shea, G.B.; Mackiernan, G.B.; Athanas, L.C.; Bleil, D.F. ; Chesapeake Bay low flow study: biota assessment. Phase I: final report. Laurel, MD: WESTECH; 1980. Cowardin, L. , Carter, M.U.; Golet,F. C; LaRoe , E.T.; Classification of wetlands and deep-water hab- itats of the United States. Washington, D.C.: U.S. Fish and Wildlife Service, Department of the Interior; 1977; 100 p. Mansueti & Hollis 1963; Ritchie & Koo 1973; and Scott & Boon 1973. Cited in: Shea, G.B.; Mackier- nan, G.B.; Athanas, L.C.; Bliel, D.W.; Chesapeake Bay low flow study: biota assessment. Plase I: final report. Laurel, MD: WESTECH, 1980. Maryland Geologic Survey. Water. Bal- timore, MD: Maryland Educational Series No. 2. ; 1970. Pritchard, D.W. Observations of Cir- culation in coastal plain estu- aries. Lauff, G.H. , ed. Estuar- ies. Washington, D.C.: Am. Adv. Sci. Publ. 83; 1966. Stroup, E.D.; Lynn, R.J. ; Atlas of salinity and temperature distri- butions in Chesapeake Bay 1952 to 1961 and seasonal averages 1949 to 1961. Graphical summary report 2. Ref. 63-1, CBI ; Balti- more, MD: John Hopkins Univer- sity; 1963: 410 p. Symposium on the classification of brackish waters. Oikos 9:311- 312; 1959. 148 FRESHWATER INFLUENCES ON STRIPED BASS POPULATION DYNAMICS J. A. Mihursky, W. R. Boynton, E. M. Setzler-Hamilton, and K. V. Wood University of Maryland, Center for Environmental and Estuarine Studies Chesapeake Biological Laboratory, Solomons, Maryland and T. T. Pol gar University of Maryland, Center for Environmental and Estuarine Studies Chesapeake Biological Laboratory, Solomons, Maryland, and Martin Marietta Corporation, Environmental Center Baltimore, Maryland ABSTRACT A population dynamics study of striped bass (Mo rone saxatilis) was conducted in the Potomac Estuary from 1974-1977. Investigations included measurements of hydrodynamic char- acteristics; water quality, phyto- plankton; zooplankton; and striped bass egg, larval, juvenile, and adult stages. Larval and juvenile food habit data were also developed. Biological data indicated that striped bass year-class success, as measured by juvenile abundance, was not closely correlated to abundance of spawning stock, number of eggs deposited or early, non-feeding Larva] stages. These results sug- gested that densi ty- independent as opposed to density-dependent mech- anisms controlled the erratic pat- terns of year-class success of this species. Climatic data were compared to available juvenile abundance data for a 25-year period. Strong year- classes were correlated with colder than average winters (December) which were followed by above average spring (April) freshwater runoft to the estuary. Larval food habit studies, coupled with earlier work concerning larval transport suggested that high densities of zooplankton at the time of first larval feeding and the spa- tial distribution of the spawning stock contributed to larval survivor- ship and consequent establishment of year-class strength. In order to provide projected freshwater supplies for human activity in the Washington, D.C., metropolitan region a number of engineering devices have been proposed, including upstream reser- voirs, inter-connections to existing reservoirs, deep-well additions and advanced waste water treatment and reutilization. A number of the above devices have the potential to change hydraulic regimes in the Potomac. The effects of these changes are discussed and evaluated with regard to maintenance of the striped bass stock. '•'•"Contrib. 1024, Center for Environ- ment and Estuarine Studies of the University of Maryland. INTRODUCTION The striped bass is an important commercial and recreational fish native to the East Coast of the United States. It is an anadromous species that migrates during the spawning season from coastal high salinity areas to the fresh or 149 slightly brackish spawning grounds in the upper reaches of estuarine sys- tems. Research and management in- terests in this species have in- creased markedly in the past decade because of stock declines. Recent bibliographies were produced by Pfuderer et al. (1975), Rogers and Westin (1975) and Horseman and Kernehan in 1976. Early accounts of striped bass life histories were published by Scofield (1931), Pearson (1938) and Merriman (1941). Raney (1952) produced a useful summary of striped bass biology and life history. Synopses of biological data on the striped bass have been devel- oped recently by Smith and Wells (1977), Westin and Rogers, (1978) and Setzler et al. (1980). The species' natural distri- bution in coastal North America is from the Alabama River on the gulf coast (Brown (1965) to the St. Lawrence River in Canada (Magnin and Beaulieu 1967). Stocking programs have successfully introduced striped bass along the West Coast of the United States where they are reported to range from Ensenada , Mexico, to the Columbia River, British Columbia (Scofield 1931; Forrester et al. 1972) . Striped bass have been intro- duced and established in numerous in- land freshwater systems in the United States (Bailey 1975) and have also been transported to Portugal, Russia, and France (Stevens 1966; Delor 1973). In the middle of their natural East Coast range (Cape Hatteras to New England) , striped bass are known to undergo extensive coastal migrations; such migratory activity is rare toward the extremes of their range. Spawning occurs in the Gulf of Mexico from February through May (Barkuloo 1961, 1970) and occurs pro- gressively later in more northern (Barkuloo 1961, 1970) and occurs pro- gressively later in more northern waters. (Raney 1952, Bigelow and Schroeder 1953, Barkuloo 1970). The Chesapeake Bay system has been identified as the principal spawning and nursery area for striped bass on the Atlantic coast and may contribute as much as 90 percent of recruitment to the fishery in Atlantic coastal waters (Kumar and Van Winkle 1978; Berggren and Lieberman 1978) . Within the Chesapeake system, the Potomac estuary contributes about 20 percent of the striped bass stock, based upon commercial landings. This species is noted for fluc- tuations in abundance which in turn are attributed to periodicities in dominant year classes. Van Winkle et al. (1979) noted that ..."stat- istically significant periodicities of approximately 20 year and of 6 to 8 year are common to the time series for most states and regions." They stated further that ..."Since the periodicities are neither very pro- nounced nor simple, it is difficult to isolate the causative factors, which are most likely to be density- independent environmental factors enhancing survival of the young than intrinsic characteristics of the life cycle of striped bass." (Van Winkle et al. , 1979: 54). There has not been a strong year-class of striped bass pro- duced since 1970 on the East Coast and the yield from the fishery has declined markedly. As a result, substantial concern has been ex- pressed and it has been suggested that contaminants are now limiting striped bass success. The effects of heavy metals and petrochemicals upon striped bass are currently being in- vestigated (Whipple et al. 1979). The reauthorization of the Anadromous Fish Conservation Act (PS96-118) 150 by the Chaffee Amendment provides for an emergency 3-year study of striped bass populations. This new amend- ment recognized that "this species is experiencing a grave crises" and calls for two major efforts: (1) to monitor the status of existing popu- lations, and (2) to identify factors responsible for the decline in stocks. The major emphasis of the former deals with describing egg, larval, and juvenile stocks, while the latter deals with toxicological investigations . While contaminants may be im- portant factors in some areas, we hypothesize that in the Potomac Estuary extrinsic climate factors in combination with spawning behavior largely determine year-class strength. Our purpose here is to present data in support of this hypo- thesis and to speculate on possible impacts on striped bass stocks re- lated to changes in the volume and timing of freshwater discharges. As part of the power industry's response to projected electricity demands, a nuclear steam electric station was proposed at Douglas Point on the Potomac Estuary, a location that has been identified as part of the Potomac striped bass spawning grounds (Figure 1). The Maryland Department of Natural Resources, initiated a target species approach to examining the possible damage factor to the striped bass fisheries of the Potomac. The major issue con- cerned the effect of increased mor- tality rates of egg and larval stages caused by pumped-entrainment activity of the proposed power plant cooling water system on future fishable stocks. Thus a population dynamics study was conducted between 1974 and 1977 and included investigations of river hydrology, water quality, phytoplankton and zooplankton distri- butions, and quantitative character- ization of the temporal and spatial abundance of egg, larval, juvenile and adult stages of striped bass. POTOMAC ESTUARY STUDY The Potomac Estuary (Figure 1), a subsystem of the Chesapeake Bay, was declared a national estuary by President Johnson. The estuary has been utilized for transportation, recreation, fisheries exploitation and sewage disposal since colonial times. Industrial activity is rel- atively low compared to most East Coast estuaries. Population growth in the Washington, D.C. metropolitan area, located in the upper tidal Potomac, has been substantial in the last few decades. This growth has caused increased demands for electricity, domestic water supplies and has resulted in the release of increasing amounts of treated-sewage effluent to the upper Potomac Estuary. Summarized in Figure 2 are striped bass egg and larval densities typical of all years of our study. Several key points can be made from these time-space depictions. While egg deposition occurred throughout most of the study area, highest egg densi- ties appeared progressively upriver from those areas where spawning was initiated. This pattern was sup- ported by data from adult stock assessment studies (Jones et al. 1978). Secondly, despite an average net downstream transport of several centimeters per second, peak densi- ties of all larval stages persisted through time in the same area of the estuary or showed a slight upstream movement. It appears that the stable position of peak larval densities was the result of the successful recruit- ment of eggs deposited late in the spawning season at upriver loca- tions. Lastly, there was an abrupt 151 Figure ]. rransect Locations foi Potoma< Estuary striped I). is;, study, 1974- 1977 Each transect consisted oi from 2 to 6 Lchthyoplankton stations which tmpled weekl; from .April through mid- Inn'- with an oblique tow using a I -m, 505 ii esh plankton net. Shore stations from transects i to 10 were seim I k ! y for juvenile striped bass during the summers of 1975 and 19 6. Adult spawning stocks were sampled weekly from mid-March through mid- la i'Ii gil] nets deployed near transects 1 (1974 only), 6, 8 and (>. The Lnserl shows the Location oi the Potomac Estuary within Chesapeake Bay. Other hi. i i"i striped bass spawning an is within the Bay include the uppei Bay, the Choptank and Man ke Rivers on Maryland's Eastern Shore and the James, York and Rapp ihannock Rivers in Virginia . 152 2 o O 2 o ' ■ ■ ' i_ 1 4i 1 >. u o 00 01 d 3 3 ^j 4-) o o Vj u a 4-1 CO oo !-l ii 03 4-1 00 a, II ~3 ■1-1 Q Cm 0) a 4-1 >, ~ CO CO ii 4-1 — I 3 ~ a CJ ■H 3 on f-4 O .* ■r-i Cm O T3 4J TJ Q- Ii U »> CO O *< 4J ~ ' — i — - d ■H TJ 4J Si o ■1 CO d Dm o 4-i 4-1 or O to 3 4-1 W ■H Si - — * Ii CO ro u Q 3 — 03 — — ■i*. E 1 CO o 03 O 4-) ~ II z o 1 — ' a. II - CO 00 — a* 01 35 * ■H Si 4-» +J 3 - 3 ■H 4-1 4-J •H 00 a 3 O d CO Cm 0) o o TJ — T3 4i d -3 "C o n 03 U u 4-1 CU u CO — >> Si CO Oi 00 CO Si CO 1—4 Ii i. — 1 a, '-. Xi CO 3 T3 CO II 3 _ d II p , O m r—4 03 1) 1! = cu XI T3 o CJ CO II 4-1 ~ n -1 33 CN 1+4 01 d CJ o ■ H • H (1/ — O Si 00 F mm 4_> 3 d d 3 00 c — 00 •H •r-i ■H o CO O U- 4-1 <_> I— i -1- suohbdo"! pasuejj^ 153 truncation of larval densities beginning in the vicinity of Maryland Point (Md. P.) and extending down- stream. This suggested to us, and was later supported by work of Ulanowicz and Polgar (1980), that late stage larvae in this area were subjected to conditions which resulted in higher than normal mortality rates. Subsequent comparisons of strip- ed bass ichthyoplankton distribu- tions, zooplankton abundances, and food habits of larval striped bass provided evidence which suggested that quantity and distribution of zooplankton in relation to the first larval feeding stages may be a key factor in recruitment success. In a general fashion, larval abundance and the number of food items per larval stomach declined with the densities of food items (zooplankton) in a down-estuary direction (Figure 3) . The sharpest gradients in zooplankton densities coincided quite well with sharp declines in late stage larval densities. Moreover, it was found that striped bass larvae fed upon the largest prey items they could capture. Using Jacobs' (1974) modi- fication of Ivlev's Electivity Index: D =^±JL r+p - 2rp where D is the selectivity index, r is the proportion of a given food type in the feeder ration, and p is the proportion of the same food in the zooplankton, larval striped bass showed a positive selec- tion for adult Eurytemora af finis , cyclopoid adults and copepodites, and the cladoceran, Bosmina longirostris and a negative selection for copepod nauplii and most rotifer species (Table 1). Since the abund- ance of the favored-prey species was similar to the general zooplankton abundance pattern, Beaven and Mihursky (1979) concluded that food may have been limiting for striped bass larvae in the lower reaches of the spawning area. ENVIRONMENTAL INFLUENCES IN RECRUITMENT SUCCESS To this point, we have built a case which suggests that recruitment success is determined by the end of the larval stage and that position in the estuary where spawning takes place and zooplankton abundance are important factors regulating this process. In this section we attempt to show that these factors are in turn influenced by several climatic variables . Several authors have success- fully related internal ecosystem characteristic to the behavior of ex- trinsic variables (Menzel et al. 1966, Aleem 1972). Copeland (1966) found that fishery yields in some Texas bays increase in years of above average river flow. Menzel et al. (1966) showed similar trends for oys- ter stocks in Apalachicola Bay, Flor- ida. Heinle et al. (1975) concluded that colder than normal winters en- hance zooplankton and juvenile fish recruitment in the Patuxent River, Maryland. Sutcliffe et al. (1976) and Sutcliffe et al. (1977) demonstrated significant correlations between catches of 17 species of commercial marine fish and shellfish and sea temperatures in the Gulf of Maine. More to the point, in the California Delta larger year-classes of striped bass seem to result from 154 CO c CD Q c o c IS a o o N o 03 > CO CD Q. CO E CD +-; ■o o o o X 3 2 lh 0 Zooplankton Density 2H 1- 0 — Yolk-Sac Feeding Success \ i no larvae "zero zero w&. c CO £ 03 o .c +-> +-> c 03 CC ^ 05 CO T3 CO C 03 03 O) >> 3 i_ o 03 Q E CO CO o Q_ Downstream -*- Upstream ^-> IB 1 o -C 1— 1 ta 4-1 > •H u s-i r* V M oi r— 1 T3 111 to d 03 e 4-1 01 4-1 i—4 4-1 ■H — i U -a O C) 0 0 o T— 1 4-1 w ij T3 M oi = C *j 0 •H •H >r^4 43 ^ ox) J2 O OJ I" o 73 4-1 o ^ a- j-j " — § C r-l ft 03 '-' >>_^ ft (0 " S-l >> 01 « E 03 o => s 4-> W U OJ w 0) 03 3 C s-i e 3 O I O U, 'H 00 4-> 01 4-1 •H O 01 03 (jm eu T3 o 155 Table 1. Mean selectivity index for larval striped bass from the Potomac Estuary, 1978 (from Beaven and Mihursky 1979). Available zooplankton No. of samples from which mean index is calculated Larval Stage Yolk sac Finfold Postfinfold Copepoda Eurytemora af finis adults E. af finis copepodites E. af finis nauplii Cyclopoid adults Cyclopoid copepodites Unidentified nauplii +0.97 + 0.95 + 0.97 -0.21 -0.39 -0.33 -1.00 -1.00 -1 .00 + 0.29 + 0.66 +0.56 +0.34 + 0.62 -0.42 -0.95 -1.00 -1 .00 Cladocera Bosmina longirostris Daphnia species Chydorus species +0.37 + 0.34 +0.31 -0.10 -0.62 -0.23 -0.60 -0.75 - Rotif era Brachinous calycif lorus Brachinous species Keratella species Filinia longiseta Asplanchna species Polyarthra species Unidentified rotifer +0.18 -0.22 -0.81 -0.46 -0.52 -1 .00 -0.70 -1.00 -1.00 -1 .00 - 1 . 00 - ] . 00 -1.00 -1 .00 -1.00 -1 .00 -1 .00 -1.00 -0.76 -0.69 -0.87 156 years of high river flow. Turner and Chadwick (1972) demonstrated that in the Sacramento-San Joaquin System survival of young striped bass (up to 3.8 cm TLJ was related to summer river flow through the delta, which controls the transport of young bass to suitable nursery areas. Stevens (1977) and Chadwick et al. (1977) have shown that these river outflows and diversion of river water to the California aqueduct system impact recruitment to the sport fishery several years later and play a major role in controlling the size of the striped bass population. Although years of higher river flow in the California Delta have resulted in large year-classes, virtually all the eggs produced in the early and mid- portions of the spawning season in these high flow years are swept into the lower bays of the delta where survival is extremely low. The mid- summer size distribution of the juvenile fish indicates that they were produced from a small fraction of late spawning fish (Chadwick 19 74). Likewise in the Potomac- Estuary, striped bass eggs and larvae apparently experience a differential mortality with a greater probability of survival toward the end of the spawning season at the up-river transects (Pol gar et al. 1976, Ulanowicz and Polgar 1980, Setzler- Hamilton et al. 1981. Such results would seem to indicate that the production of a successful year-class is largely a dens lty- independent phenomenon, a conclusion first alluded to by Vladykov and Wallace (1952). available and several functions of these were used singly and in combi- nation as predictors of recruitment success. Summer surveys of juvenile striped bass relative abundance have been made in the Potomac since 1958. Recently, this data set has been shown to be a good indicator of both recruitment success (Polgar 1977, Ulanowicz and Polgar 1980) and com- mercial catch (Boynton et al. 1977) and was used here as the dependent variable in regression analyses. Results of a single factor and multiple factor analyses are sum- marized in Table 2. In general, statistically significant relation- ships were indicated for several functions of river flow and air temperature although the percent of the variability explained by the regressions was quite low (about 25%) . The percentage of the vari- ability explained using multiple linear regressions was considerably better (about 70%) and in all cases the 5-day maximum flow in April was the strongest predictor. A three- dimensional plot of this regression is shown in Figure 4. Note that all dominant year-classes are clustered in the quadrant bounded by colder than normal winters and greater than normal spring river flows. Addi- tional plots were made using the same temperature function but the highest five-day mean flow occurring in either March or May. Interestingly enough, the previous pattern was not observed suggesting that the timing as well as the quantity of river flow is an important factor in determining recruitment success. We reviewed several climatic data sets in an attempt to identify extrinsic factors which may play a strong role in regulating recruitment success. Such analyses are obviously constrained by the types of data available; in our case air tempera- ture and river flow were readily As in all statistical models, significant results or interesting patterns are, per se, incomplete; causation is certainly not demon- strated and for the model to be help- ful we need to be able to suggest mechanisms responsible for the statistical results. In our case, we 157 Table 2. Regression model summary. LINEAR REGRESSIONS Correlation Degree Independent Variable Coefficient Value River Flow Freedom Significance April 5-day mean high flow Total April flow March-May (e) April-May (j) February-April (j; ) March - April ( v) 0.51 4.24 1/12 10>p>.05 0.51 4.60 1/12 10>p>.05 0.45 3.08 1/12 10>p> .05 0.40 2.27 1/12 10>p>.05 0.49 3.79 1/12 10>p>.05 0.48 3.73 1/12 10>p>.05 Temperature Deviation from mean December -0.50 January -0.33 December & January -0.53 Freeze-Thaw Cycle December 0.47 January November 6.16 2.37 7.10 5.36 0.15 0.09 1/18 1/18 1/18 1/19 1/19 1/19 p<.025 N.S. p<.025 p .05 N.S. N.S Independent-Variables r Value April 5-day maximum flow and December Temperature Deviation 0.84 April 5-day maximum flow and December-January Temperature Deviation 0.82 April 5-day maximum flow and December-February Temperature Deviation 0.79 1 Juvenile index is dependent variable 158 |neH auias Jad sseg paduis '°N 'x^pui aimaAnp 1 a; *J 01 -a a •H B 01 u U CD d *J OJ 11 T- ^H •H 3 01 a; u > 3 -t 4-> ■i-i cb S-i T3 CD d a m in CD «, 4-> /— N CO U LH HI U ,JO '"— ' e i—l u 0) Q ■H (-1 ft < 4-1 d 0 •H 4J O o ^H m ft S-I |H cu CO > d ■H 0 « •H 1/1 U d nd OJ E R o •H *J Tl 0 u- OJ „ OJ ^-N h C ) Jt o H +1 ^— • CO 01 S-4 01 d >-J 4-> 3 M 60 Sj • H 01 U* a 159 currently hypothesize that low winter temperatures act to slow terrestrial losses of detritus and nutrients until the spring thaw at which time these materials are deposited in the river in larger than normal quanti- ties. Heinle et al. (1976) suggested that ice-scour of marshes in the Patuxent River was more complete in cold winters and served as an addi- tional organic matter source for zoo- plankton which in turn were more available to first-feeding larvae. River flow may act through several mechanisms and, at this juncture, we are uncertain as to the relative importance of these. One concept has it that higher than normal spring flows transport detritus and nu- trients to the spawning area in greater abundance than in lower flow- years. The enhanced load supports densities of zooplankton at levels appropriate for first-feeding larvae. Another concept extends the first, and suggests that higher than normal spring flows support higher zoo- plankton densities but also expands the area of the river which has this characteristic. Thus, there is a larger nursery area in which zoo- plankton stocks are above critical densities for first-feeding larvae (Polgar et al. 1978). An emerging view is that there is always some zone of the upper nursery area which has sufficiently high zooplankton stocks to support some recruitment, even in years of average or low flow. In this view, the key to successful recruitment involves the distribution i't spawning adults. Preliminary analyses suggest that certain water temperature patterns in tht spring (which are influenced by river flow) act to delay spawning until adult tish have migrated far up into the spawning area. When spawning does occur, ^merging larvae have suffi- cient time to grow through the critical feeding stages prior to being transported out of the rich nursery area. During years of high flow, the area! dimensions of this zone expand. ["hus , while we can suggest and, by inference, support several mechanisms, further refine- ments are obviously needed. HYDRAULIC ALTERATIONS OF THE POTOMAC ESTUARY The United States Army Corps of Engineers, in response to legislation requiring the development of water supply plans for major Northeast metropolitan regions, has assisted in developing such a plan ior the Washington, D.C. ,ict\i. The overall program, commonly referred to as NEWS 2020, is the Northeast Water Supply plan to the year 2020. [Tie Washington metropolitan area obtains the major portion of its water supply from the Potomac River upstream of Great Falls. As given in Figure 5, the minimum low flow re- corded was 388 million gallons per day (mgd) on September 196b, while the peak summer withdrawal was 488 mgd on 18 July 1974. A key issue then is the adequacy of river flow to meet demand during 1 ov How periods. Early alternatives suggested were installation of dams on the mainstem river or tributaries in order to withhold spring excess flow and to release tins water during summer Low flow periods. Subsequent considera- tions were various water conservation scenarios (Figure 5 and Table 3; Water Forum Notes 1978). Although conservation efforts may reduce pro- jected increase demands, there still remains the possibility oi storing a portion of excess spring flows to in.ot. future water needs. If spring I 1 ows are critical to sir iped bass success in the Potomac, it may be that future conflicts will develop 160 900 800- C o E Q £ 700 o Q o, 600 o i_ a) > < J 500 d" a. 400 baseli ne «/> c ,0 "5 2000 1980 2000 2020 Time Horizon ^ o Q '5 D c o 1000 Jun1 Jul 'Aug' Sep 1966 Figure 5. Projected average daily water demands for the Washington, metro- politan area until the year 2030. See Table 3 for explanation of null and baseline projections and projected water demands based on various conserva- tion scenarios. Lower graph depicts daily discharge of the Potomac River at the Washington D.C., gauging station from June-September 1966; the lowest summer flow on record. Peak summer withdrawal for the Washington Metropolitan area was 488 on 18 July 1974; 1966. minimum; low flow was 388 mgd on 10 September 161 Table 3. Summary of alternate water conservation scenarios for the metro- politan Washington area (from Water Forum Notes 1978). .Null -Projection of current rates of water use with no operation changes imposed. .Baseline -Projection of current rates of water use with incorpora- tion of current and anticipated metropolitan Washington Area plumbing regulations. .Scenario 1 -Baseline plus: Additional low water use fixtures to new residential con- struction, retrofitting water-saving devices to existing residential , .Scenario 2 -Scenario 1 plus: A reduction in outdoor residential water use achieved through a water conservation educational campaign directed at changing individual water use habits, .Scenario 3 -Scenario 2 plus: A reduction in indoor and outdoor nonresidential water use achieved through a water conservation educational cam- paign directed at employees' personal use and manage- ment's water use habits, .Scenario 4 -Scenario 3 plus: A reduction in the unaccounted for water use by mini- mizing the amount of water lost from leaks through system improvements, and .Scenario 5 -Scenario 4 plus: The most efficient available low-water use fixtures to indoor new residential and nonresidential; retrofitting water-saving devices to existing residential; a behavior modification to indoor and outdoor, new and existing residential and nonresidential water use; and a reduction unaccounted for water use by minimizing the amount of water lost from leaks through system improvements. 162 between the need to meet domestic/ industrial water supply requirements and flow requirements needed for successful striped bass recruitment and maintenance of fishable stocks. Given the data we have available con- cerning storage capacity, it is not possible to calculate how much of the spring peak could be placed in storage. In any case, it seems pru- dent to consider the possibility of storing river water during periods of the year when flow substantially exceeds demand either prior to or after spawning events. high discharge. Larvae apparently have sufficient time to complete the critical stages prior to being trans- ported out of this zone. The above represents what appears to be a con- sistent pattern, but one that may nonetheless be modified as analyses continue. Concerning the role of river flow and striped bass success, the case we have built for the Potomac suggests that any significant diminution of springtime freshwater discharge to the estuary would tend to decrease the probability of sub- stantial recruitment success. CONCLUSIONS Intensive sampling of fish egg and larval populations, zooplankton distributions and results of larval stomach analyses indicated that first-feeding larvae represent the critical stage in striped bass re- cruitment and that high densities of zooplankton are necessary for suc- cessful recruitment to occur. Adult spawning stock size is seen to be relatively unimportant compared to factors controlling zooplankton densities and distributions in the estuary. We have tried to build a case which invokes winter temperature patterns and spring river flow as important factors influencing the density and areal distribution of zooplankton and perhaps the migration pattern of adult striped bass. In years having low winter temperatures and high river flow, adult bass appear to move farther up river prior to spawning, possibly due to tempera- ture regulated spawning patterns. Eggs are deposited at the head of the spawning area which has sufficient organic matter resources, due to high freshwater discharge, to support zoo- plankton populations at densities required by first-feeding larvae. The areal extent of the zone char- acterized by high zooplankton densi- ties is also enlarged during years of LITERATURE CITED Aleem, A. A. Effect of river out- flow management on marine life. Mar. Biol. 15 :200-208; 1972 . Bailey, W.M. An evaluation of striped bass introductions in the South- eastern United States. Proc. 28th Annu. Conf. Southeast. As- soc. Game Fish Comm. 1974:54- 68; 1975. Barkuloo, J.M. Distribution and abundance of striped bass (Roc- cus saxatilis, Walbaum) on the Florida Gulf Coast. Proc. 15th Annu. Conf. Southeast Assoc. Game Fish Comm. 1961:223-226 Taxonomic status and repro- duction of striped bass (Morone saxatilis) in Florida. U.S. Bur. Sport Fish. Wildl. 16 p. 1970; Tech. Pap. 44. Beaven, M.; Mihursky, J. A. 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The life history of the striped bass, or rockfish, Roccus saxatilis (Walbaum) .U.S. Bur. Fish. 825-860; Bull. 49, 1938. Pfuderer, H. A.; Talmage, S. S.; Col- lier, B. N.; Van Winkle, W.,Jr.; Goodyear, C. P. Striped bass-a selected annotated bibliography. Oak Ridge Natl. Lab., Environ. Sci.Div.; 1975; 158 p. Publ.615. Polgar, T.T. Striped bass ichthy- Rogers, B. A.; Westin, D. T. A bib- liography on the biology of the striped bass, Morone saxatilis (Walbaum). Univ. Rhode Island; 1975; Mar. Tech. Rep. 37. 134 p. Scofield, E. C. The life history of the striped bass, The strip- ed bass of California, Roccus lineatus. Div. of Fish & Game of Calif.; 1931: 36-60. Fish. Bull. #29. 165 Setzler, E. M. ; Boynton, W. R.; Wood, K. V.; Zion, H. H.; Lubbers, L.; N. Mountford, N. K. ; Frere, Tucker, L. ; Mihursky, Synopsis of biological on striped bass, Morone tilis (Walbaum) : P; • J. A. data saxa- 1980; NOAA Technical Report NMFS Circular 433, FAO Fisheries Synopsis No. 121. Setzler-Hamilton, E. M.; Boynton, W. R.; Polgar, T. T. ; Mihursky J. A.; Wood, K. V. Spatial and temporal distribution of striped bass eggs, larvae, and juveniles in the Potomac Estuary. Trans. Am. Fish. Soc. 110:121-136; 1981. Smith, W. G.; Wells, A. Biological and fisheries data on striped bass, Morone saxatilis (Walbaum). Sandy Hook Laboratory, Northeast Fisheries Center, NMFS, NOAA, U.S. Dept. of Commerce, High- lands, N. J. Tech. Ser. Rep. 4; 1977. Stevens, D. E. Food habits of striped bass, Roccus saxa- tilis , in the Sacramento-San Joaquin delta. Turner; J. L.; Kelley, D. W. compilers, Ecolo- gical studies of the Sacramento- San Joaquin Delta. Part II. Fishes of the delta, Calif. Dept. Fish Game, Fish. Bull. 136:68- 96; 1966. Stevens, D.E. Striped bass, Morone saxatilis , class strength in re- lation to river flow in the Sa- cramento-San Joaquin Estuary, California. Trans. Am. Fish. Soc. 106:34-42; 1977. Sutcliffe, W.H., Jr.; Drinkwater, K.; Muir, B. S. Correlations of fish catch and environmental factors in the Gulf of Maine. J. Fish. Res. Board Can. 34:19-30; 1977. Sutliffe, W.H., Jr.; Loucks , R. H.; Drinkwater, K. F. Coastal cir- culation and physical oceano- graphy of the Scotian Shelf and the Gulf of Maine. J. Fish. Res. Board Can. 33:98-115; 1976. Turner, J. L.; Chadwick, H. K. ; Dis- tribution and an abundance of young-of-the-year striped bass, Morone saxatilis , in relation to river flow in the Sacramento- San Joaquin estuary. Trans. Am. Fish. Soc. 101:442-452; 1972. Ulanowicz, R. E.; Polgar, T. T. In- fluences of anadromous spawning behavior and optimal environ- mental conditions upon striped bass, (Morone saxatilis) year class success. Can. J. Fish. Aquat. Sci. 37:142-154; 1980. Van Winkle, W. ; Kird, B. L. ; Rust, B. W. , Periodicities in Atlan- tic coast striped bass (Morone saxatilis) commercial fisheries Fish. Res. Board data. J. 36:54-62; 1979 Can. Vladykov, V.D. ; Wallace, D.H. Stu- dies of the striped bass, R. saxatilis (Walbaum), with spe- cial reference to the Chesapeake Bay region during 1936-1938. Bull. Bingham. Oceanogr. Coll. 14(1) : 132-177 ; 1952. Water Forum Notes. Metropolitan Washington Area Water Supply Study, No. 4; Dec. 1978. Balti- more, MD: U.S. Army Corps of Engineers, 1978. Westin, D.T. ; Rogers, B.A. , Synopsis of biological data on the strip- ed bass, Morone saxatilis (Wal- baum) 1972. Graduate School of 166 Oceanography, Kingston, RI : Univ. of Rhode Island, Marine Technical Rep. 67; 1978. Whipple, J. A.; Eldridge, M. ; Ben- ville, P.; Jarvis, B. ; Bowers, M. The impact of estuarine de- gradation and chronic pollution on populations of anadromous striped bass (Morone saxatilis) in San Francisco Bay-Delta, Cal- ifornia. A report submitted to the NOAA, Office of Marine Pol- lution Assessment, 6010 Execu- tive Boulevard, Rockville, MD; 1979. 167 EFFECTS OF FRESHWATER FLOW ON SALINITY AND PHYTOPLANKTON BIOMASS IN THE LOWER HUDSON ESTUARY Patrick J. Neale, Thomas C. Malone and David C. Boardman Lamont-Doherty Geological Observatory, Palisades, New York ABSTRACT INTRODUCTION A two dimensional box model was used to describe variation of phytoplankton biomass in the lower Hudson Estuary under different flow conditions. Both the flux contribution of estuarine circu- lation and other gain or loss pro- cesses are quantified by the model. Lag between gauging data and freshwater flow in the estu- ary, the vertical structure of current velocity and salinity, and the tidal variation of salinity in each layer were considered in the estimation of model parameters. Results indicate that estuarine circulation was strong and flush- ing times relatively short under both high and low flow conditions. Biomass fluxes in terms of chloro- phyll a were dominated by bound- ary inputs during high flow and by growth and grazing during low flow. The good agreement found between independent measurements of specific rates and specific rates estimated from the model indicates that the model gives a reasonable description of estua- rine phytoplankton processes, and may be applicable in other estuaries . Phytoplankton biomass variations in estuaries are primarily the result of material fluxes due to estuarine circulation and fluxes due to biolo- gical and particulate processes (e.g. growth, sinking, and grazing). Thus fresh water effects on estuarine circulation can be translated to effects on phytoplankton biomass if the relative contribution of circu- lation-related fluxes is known. In this paper we approach the problem by using models of circulation to make estimates of each flux component dur- ing different freshwater flow condi- tions . Simple, first order models have been used successfully to study pol- lutant (Pritchard 1969) and nutrient (Simpson and Hammond unpublished; Taft et al. 1978) distributions in partially mixed estuaries. These models do not include explicitly the dynamics of circulation or details of diffusion processes, but lump all effects into a small number of para- meters. A one-dimensional descrip- tion of the tidally averaged concen- tration of some property C is given by the advection-dif fusion equation: 168 1 A 2- (EA 5- C 8x 8 x I QO ■ | I U) A = cross-sectional area Q = flow rate E = dispersion coefficient E includes the effects of upstream bottom advection and tidal mixing. If E is constant with distance and C is constant with time (steady-state), C is exponentially distributed, i.e. C (x) = Coexp TV A) + C (la). This model has been useful in the study of longitudinal salt distributions (Simpson and Hammond unpublished; Stommel 1953), but is of limited use in problems where vertical variations are important (Hansen 1967). This is the case for phy- toplankton distributions in the lower Hudson Estuary (Malone et al. 1980) which is partially mixed and characterized by two- layered flow (Abood 1974). A simple model which incorpo- rates vertical variation is the two-dimensional box model (Prit- chard 1969, Taft et al. 1978). In this model the estuary is divided into a series of longi- tudinal segments and each segment is divided vertically into two layers at the boundary between up- and down-stream net non-tidal flow. Assuming that salinity distribution approximates steady state, and following the notation of Pritchard (1969), the equations defining transport are: Qul = Qf su/rsii ui Qn = Qf sui/fsH - sui: Qvi where Q Qui+r ^i (2) (3) ui upper layer downstream flow at the i boundary Q.. . = lower layer upstream flow at the i boundary S . ,S = upper and lower layer tidally averaged salini- ties at i boundary Qf = freshwater flow Q . = vertical flow between .th , , . ,.th i and (i + 1) boundary These equations are derived from continuity of salt (Q . S . = 0 . ui ui Mi S ) and fresh water flow (Q = Q . - Q, . ) . Defining the mean ui li 6 salinity in the upper and lower layer box between the i and i + 1 boundary as Mui=^(Sui+l+Sui)' Mn = ^(si1+i + sn> <*> continuity of salt in each box is attained by the parameter E. (verti- cal exchange) in Q . S . - (Q . , S . ,+ Q . M, . ui ui ui-1 ui-1 VI ll + E. [M, . - M .]) = 0 (5) 1 li ui Q1 . S. . - (Q. . . S. . . + Q . Mn . li li li-l li-l vi li + E. [M. . - M .]) = 0 (6) 1 li ui 169 If property 'C is substituted into Eqs . (4), (5) and (6), Eqs . (5) and (6) define the time rate of change of the amount of ' C in each box d M ui V ./dt ui and d M li 'V with appropriate sub- vu/dt, scripts denotes volume. Dividing through by volume (independent of time to the order of the estimate) and using Eq. (4) to transform equations in 'M' to equations in 'C defines a matrix equation d C/dt = A C + p (t) (7) C = vector of box boundary property concentrations (upper and lower) A = matrix of coefficients derived from Eqs. (4), (5) and (6) This paper discusses the rela- tions between freshwater flow, cur- rents and salinity in the lower Hudson Estuary relevant to the con- struction of a box model, and applies the model to the distribution of chlorophyll a , an index of phyto- plankton biomass. The Chlorophyll a field derived from the model can be compared to observed Chlorophyll a field to determine whether additional source (growth, resuspension) or sink (grazing, sinking) terms are needed to balance Eq. (7). These terms can be calculated by direct substitution of observed C's into Eq. (7). Thus the model provides a method for separating the component of the phytoplankton dynamics due to circu- lation from other effects and the estimation of flushing times of phyto- plankton from the estuary. The characteristics of the data set used are discussed in Malone et al. (1980) and the present work extends and re- fines the flux calculations given therein. p(t) = vector of boundary condi- tion functions MATERIALS AND METHODS If dC/dt = 0 (property in steady- state) and inputs occur in upper layer upstream boundary and lower layer downstream boundary, algebraic substitution shows that Eq. (7) is solved by C . = a S. + b, a and b determined by the boundary condition C, S pairs. This model improves on Pritchard (1969) by letting concen- tration variables define box boundary concentrations with mean box values calculated by Eq. (4), whereas the opposite approach is used in the previous model. This optimizes the use of observed salinity data by using it directly in Eq. (2) which is sensitive to small changes in salinity. Samples were collected at ap- proximately weekly intervals from February to June and July to Septem- ber during 1977 and 1978. Surface chlorophyll (in vivo fluorescence) and salinity (conductivity and temp- erature) were monitored continuously with and against the tide along a transect between MP -7 and MP -25 (Figure 1). Vertical profiles of current speed and direction, tem- perature, salinity and chlorophyll a were obtained at 6 stations (Figure 1) with a Savonius rotor current me- ter , conductivity-temperature-depth sensor, submersible pump and bottle casts. Vertical profiles were ob- tained every 1 to 3 h over two tidal cycles on 8 occasions at MP -7 and 2 occasions at MP 18. Bottles were used to collect samples for extracted chlorophyll a and primary productivity 170 Figure 1. The Lower Hudson Estuary with station locations and box boundaries indicated by lines normal to axis at MP -7, MP -3, MP 0, MP 6, MP 11, MP 18 (MP = mile point, miles north (+) or south (-) of the Battery). Insets show cross-sectional profiles at MP -7, and MP 18. The Upper Bay station location actually varied between MP -4 (1977) and MP -2 (1978). 171 experiments as described by Malone (1977). Netplankton and nannoplank- ton refer to phytoplankton popula- tions that were retained and passed by a 20 ym mesh screen, respectively. Freshwater flow of the Hudson River at Green Island (250 km north of Upper Bay) was provided by the Water Resources Division of the Geological Survey, U. S. Department of Interior. Total freshwater flow in the lower estu- ary was calculated by applying a correction for lower basin flow (Hammond 1975; Deck 1980). Cross-sectional areas for each station were obtained from fathom- eter profiles, and volumes north of MP 0 were calculated using linearly varying area. In the upper bay the dimensional data of Quirk, Lawler, and Matusky (1970) was employed. RESULTS AND DISCUSSION FRESHWATER FLOW During water flow 1977 and at Green .7 1978, fresh- to below 2 The 25-year 10 m d . 10 ,7 Island (Q ) 3 -1 m d (spring) m d ranged from 37 x 7 3-1 x 10 m d (summer) . annual mean is 3.1 x In the spring there were large amplitude peaks of short duration which arrived earlier and were higher in 1977 than in 1978 (Figure 2) . Summer flow was much lower and less var- iable (1977 x = 1.23, sd = 0.31, 1978 x = 1.32 sd = 0.37). Green Island is located at mile point (MP) 154, 136 miles upstream from the northern most station. Conse- quently, two corrections must be applied to Q to estimate fresh- water flow into the lower estuary (Qf ) : (1) lower basin inputs must be added to Q and (2) a lag must be used to account for the time required for a change in QpT to be reflected in Q . Hammond (1975) and Deck (1980) adjusted Q for lower basin contributions to freshwater flow in the estuary (Q ) , but possible lag times and spreading of flow peaks were not accounted for. Lag time estimates range from 5 to 20 days (Stewart 1958; Hammond 1975), though the possibility of shorter times in the spring has been noted (Hammond 1975). Since adjusted Q can change ul as much as 25 x 10 d in as lit- tle as 4 d during spring (Figure 2), this is the season when accurate lags are most needed. Lag times between Q T and Qf were examined through the corre- lation of < S > , the average sur- face salinity between MP 25 and MP -7. QpT was adjusted as above and smoothed1 by a centered moving average to allow for flow peak spreading during transit. The aver- aging period was varied as a function of the lag (Table 1). During high flow (Qf > 5 x 7 3 -1 10 m d ) variations in < S >x were mainly a function of QHf changes. By comparing variations in Q„T with variations in < S > a lag of 1 day was found to give the maximum correlation (Figure 2) . The correlation was also examined by fitting < S > = ( < S > ) exp (b Q ) (cf. Eq* la) for lag Xt?mes of 11, 7, and 1 days. A one-day lag time gave the best fit 7for, D2t.h high and low (Qf 5 x 10 m d ) flow conditions liable 1). Such a short lag under low flow condi- tions indicates the poor sensi- tivity of the model during low flow since this lag is shorter than the minimum low flow lag of 5 d calcu- 172 OO 00 »9 00 ss oo "eV oo -o> 00 ZE x 'JO oo >i 00 •91 00'8 "bPiP .lOf— -a o oZ OCT 00 -»9 00 ^'s 00 -8» 00 0* 00 "ZE x -a: a <=z OCT X! 0) oo oo CO d CO OJ ■P O o s co O d d •H PS d o w 3 .d ch o 3 o u a CO -d OJ M eg 0) d 60 U O 4-1 >» CO d 4-1 CO hi d o CO •V d « S-l cu O OJ J3 T5 d CO W d o xi u OJ & CO 4-> U CO ft + A *■— ' 10 V .2 '-o CO fc r- H o CO 4-1 3 II ch -J0 00 »z 00-91 00 '8 00 d CO y^ > CO T) r-~ r-~ o pt| 1-H I-H 173 oo co 13 d E C •H 03 co r~ 3 o r~- M 0> a X X O" lO 4-1 T3 S-l 0) a| o X lM 4-> ih o o* O ^^ e ..*» t/j 3 * O -\<" T3 i—l #■ G 4-1 ^» oJ 3 CO -o O 4-1 ai 1— 1 X 4-1 oo ca T3 ■H 3 d 01 ■•—i 03 3 T3 03 / \ X) r-H 4-1 c 1 ■H o T3 3 ^ co 01 X E 00 03 A r- Sh w O 0) V X > 03 >> >1 • 4-> m OJ 00 ■H TJ 03 CI A| rH •H 0) i— 1 4-1 01 01 03 o* l-i X CO \— * XI 4-1 4J 01 3 o o o 03 4-1 « l—l m 4-1 X r— 1 i-i 4-1 03 3 X •r-l 3 co oo 3 o< •H CU C X -o (0 0) T3 CD Sh X O E o 4J ■H 4-1 o Sh 4-1 o 01 o f — s E Cu 4H CO c O* 03 o co •H XI 03 S-l 10 ^^ 3 0) CO > CU o, n o 00 X o 0) 0) o- T3 S-l CU oo X S-l o 03 4-1 o r^ 1— 1 o 4-i X o A >^ E CO ai 03 co u V TD •H ^_/ CO 4-> i — i 03 CO || 3 •H 4-1 OJ i — i 03 X X a 4-1 A 4-1 o- t/3 CO V S-l oo o 03 c 1*4 r— 1 t— 1 o •H >» CD 4-1 03 r-H CO / — \ TD XI 3 03 cr 1 r-H H 0) T3 l—l tn O 3 O h-1 A CO V 3 o r-H l-H X oo CO d CN CO a o \0 CO CO co cm o CM a\ r~- cm o as c~> l-H O rH r— vo -J CO i—i CM CM CO CM CO -;c d ^s 00 00 o> CO CO CO -3- r~- 01 v£> r-H 3 O lO r-H 4-1 i— i V 0) E •H /— N 4-1 ^3 r-H r^ 00 03 hJ d 03 u •H 4-1 •H d oo 4-1 o c a o ■H CO 10 OJ Sh 00 01 Sh CO c m o 174 MP -4 0 11 18 10. 10. 10. 10 .5, SALINITY nP . -s. 1 10 10. 10 10. 10. 1. Figure 3. The correlation (r) of original variables and the first two principal components from vertical profiles of current velocity and salinity at stations in the lower estuary in 1977. Velocities or sa- linities that correlate with a common component tend to co-vary. On this basis components were labelled "surface" ( o ) or "bottom" (A ) . Similar results were obtained from analysis of 1978 salinity data. 175 lated from the volume of water needed to create a Green Island to Battery gradient (Hammond 1975). However, since variations in Qgj during this time are small, the lag-related errors in Qf estimates are also small and 1 day lag time was used under all flow condi- tions . SALINITY PROFILES Tidally averaged salinity in the upper and lower layers are need- ed to compute volume transports between layers and boxes. Since the required data are not avail- able except occasionally at MP -7 and MP 18, an empirical model of tidal variations in salinity was used to estimate tidal averages given a salinity profile and the vertical boundary between surface and bottom layers at each sta- tion. The vertical boundary was determined by examining the prin- cipal components (Morrison 1976) of velocity and salinity profiles averaged over 2-m sections at each station (Figure 3). Two components accounted for most of the variance (94%-98%) in both velocity and salinity. Varimax rotation (Morrison 1976) of the two-compo- nent structure at each station showed a "surface" and "bottom" component with a mid-water column boundary (Figure 3). The velocity and salin- ity structure at each station was similar, in agreement with the Hud- son's classification as a partially mixed estuary with dominantly two layer flow. Using this analysis as a guide, upper and lower layer mean salinities were determined from depths having a larger correlation with component 1 or component 2, respectively. These upper and lower layer salinities were then used to esti- mate tidally averaged salinities by using them to fit an empirical model for salinity distribution in each layer. S (x,t) = So exp (-kx) + St (-COS (2 TVt)) (9) x = distance upstream from MP -7 t = proportion of time elapsed in tidal cycle (LWS-LWS) at x (deter- mined from USCG tide tables) S = half tidal range, Sq = mean salinity at MP -7 k = fitted advection- diffusion parameter An estimate of tidally averaged salinity was then obtained by in- tegrating (9) over the tidal cycle at each station. Since the equa- tion is non-linear, Gauss-Newton non-linear regression was used to determine the least squares set of parameters (Snedecor and Coch- ran 1978) for each set of two successive sampling times (1 day apart 1977, 1 week apart 1978). Data were not pooled if Qf changed significantly during the sample period, and data sets with less than 2 degrees of freedom were omitted. 176 This empirical model account- ed for observed distributions fairly well, implying a relatively small contribution to S (x,t) by higher order terms such as dis- tance dependent S and other peri- odic tidal components. The fit- ted equations had high coefficients of determination (1977 20 out of 22 had r^ > 0.88, 1978 17 out of 20 had r > 0.83) and estimated half- tidal ranges were close to ranges observed at MP -7 and MP 18 when profiles were obtained at 1-3 h in- tervals. Variations in k reflected the decrease in longitudinal salinity gradient from spring to summer and stronger gradients in the upper than the lower layer. Using the same method on whole water column aver- ages, an average lower estuary xross- section area of 1.8 x 10 m , and Q as calculated above, values of E (= -Qf/kA) from 500 to 5000 m /s were calculated over a Q range of 2 - 20 x 10 m d . Simpson and Ham- mond (submitted) have suggested 500 to 2500 m /s for lower estuary over a Q range of 2 - 10 x 10 m d VOLUME TRANSPORTS Mean transports under high and low flow conditions were higher than mean Q_ in each layer (Figure 4). The ratio of Q to Qr ranged u 1 from 2 to 6 under high flow condi- tions and from 5 to 12 under the low flow conditions. Ratios of 10 to 40 have been reported in other partially stratified estua- ries, e.g. the James River (Prit- chard 1967), Mersey Estuary (Bowden 1960) , and Juan de Fuca Straight (Tully 1958). Differ- ences in this ratio between high and low flow periods were primar- ily due to changes in Q with Q (and Q ) remaining relatively con- stant. Such stability over a wide range of Q reflects the inverse relationship between Qf and vertical salinity gradients and is primarily a consequence of an increase in verti- cal exchange under low flow condi- tions (Figure 4) . CHLOROPHYLL a DISTRIBUTIONS Mean upper and lower layer Chlorophyll a concentrations for the box model were computed from vertical profiles of Chlorophyll a by averag- ing over the depth ranges used to average salinity. When profiles were available from two consecutive days at a given station they were aver- aged. Tidal variations in Chloro- phyll a were considerable but, unlike salinity, tidally averaged profiles were not calculated. Mean Chloro- phyll a over two tidal cycles at sta- tions MP -7 and MP 18 had average coefficients of variation of 44 per- cent (27 to 607o) in the upper and 31 percent (16 to 57%) in the lower layer. However, the upper and lower layer Chlorophyll a concentrations were positively correlated (r 0.60 to 0.99, P< 0.05) except in May 1977, 1978 when r was not significant. This implies that the between layer dif- ferences used to calculate source and sink terms were less variable than Chlorophyll a concentrations used to calculate upper and lower layer fluxes . Flushing times were calculated by applying Chlorophyll a distribu- tion data to Eq. (7) and setting the boundary inputs to zero. Solutions for time varying Chlorophyll a ob- tained through the method of similar- ity transformations (Noble and Daniel 1977) had the general form of p, exp (Ak1-) + pQ, where A, is the k eigenvalue of A (Eq. 7) and the p's 177 18 M^ mi 15 11 4T 11 18 MP -^> 4T 11 21 -3 ■ *%> -^ If 20? ST 13? 13? 32 29 34 57 IB) 13 2? 28 15 -^> 2? 23 17 <3- — I -^> -^> 4? 34 3? 27' 21 24 -^> 7? 33 31 (CI ID) 26 87 1ST 38' Q 132 E49] 44? 59 14^ ^ Go] 195 36? 30 00 261 31? 86 30 450 13 4? -18 39 -2V 5? -8 ElE 48 10Q L3 10T -6 -41 93 12T7 RT1 133 ^> 35T 22 -30 219 29 18 10 KM 1 3) (14) (24) 0 -5 (41) -11 (33) Figure 4. Two dimensional box model for the lower Hudson Estuary for sta- tions between MP 18 and MP -7. Models (A) and (B) are for volume transport (10 m d ) during high flow and lyw flow periods respectively. Models (E) and (D) are for mass transport (10 mg Chi ad ), during high and low pe- riods respectively. Arrows indicate downstream upper layer flow, upstream lower layer flow, and vertical advection from lower to upper layer. Double headed arrows in (A) and (B) indicate the vertical exchange coefficient, E (10 kg d ppt ). Double headed arrows in (C) and (D) indicate vertical transport of Chi a due to exchange ([ + ] upward [-] downward), and source (+) and sink (-) fluxes are in the center boxes. 178 are constants. Flushing times de- termined from the full solution (t , time to 90% of difference between initial and asymptotic total amount of Chlorophyll a in the estuary) were found to be close to -In (0.1)/ \ which is the 90 percent decay time for A , the smallest magnitude eigenvalue of A Solutions for speci- fic boundary conditions were about \ day less than t and in only 2 out of 25 cases did the difference slightly exceed one day. Using this simpli- fication, response times averaged 2.8 d during high flow and 5.3 d during low flow. The minimum (0.8 d) oc- curred during 1977 peak flow and the maximum (6.8 d) during 1977 low flow. Because of the relative stability of estuarine net circulation with re- spect Qf variations (Figure 4) , flushing times remain short even during low flow periods (c.f. Ketchum 1967). A well-mixed lower Hudson Estuary (i.e. Qf <<< tidal flows) would not be as stable. Mean water residence times (=Estuary volume/Qf) would be longer, increasing from 7.6 d (high flow) to 26.0 d (low flow). CHLOROPHYLL a FLUXES In light of the possible effects of variability of Chlorophyll a on scales of a tidal cycle (discussed above) to several days (discussed below) , we chose to examine the mean Chlorophyll a fluxes during high and low flow periods (roughly winter to early-spring and late spring to summer). Though this does not resolve short term variations, such as the occurrence and fate of parti- cular phytoplankton blooms, a fairly reliable picture emerges of Chloro- phyll a fluxes in terms of the sea- sonal variation of flow regime and biomass of phytoplankton size frac- tions (Malone 1977, Malone et al. 1980). Input fluxes to the estuary reflected the occurrence of net- plankton blooms in adjacent coastal waters and advection into the estuary under high flow and growth of nanno- plankton within the estuary under low flow conditions (Malone 1977, Malone et al. 1980). During high flow the main source of Chlorophyll a was at the mouth of the estuary (MP-7) in the lower layer (Figure 4), where bottle samples had a mean of 64 percent Chllorophyll a in the net- plankton fraction (range 49-90%). The most important input during low flow was the upstream boundary upper layer where nannoplankton accounted for 92 percent of Chlorophyll a on the average (range 82-97%). A small- er input of Chlorophyll a occurred at MP -J (12 x 10 mg Chi a d vs. 35 x 10 mg Chi a d at MP 18), and, unlike the high flow period, was not dominated by net-plankton (mean % net 31%, range 2% to 84%). Fluxes within the estuary showed that Chlorophyll a propagated longi- tudinally and vertically away from its sources (Figure 4). Chlorophyll a was advected upstream during high flow by a consistently larger lower layer influx than downstream upper layer flux. Vertical advection and exchange transported Chlorophyll a from the lower to upper layers. Thus the flux of Chlorophyll a during high flow followed the longitudinal and vertical flux into the lower layer, a consequence of vertical exchange fluxes from sources in the upper layer. South of MP 0 net vertical fluxes into the upper layer reflected the lower layer input at MP -7. The high flow pattern of large sinks in the upper layer and smaller source fluxes in the lower layer (except between MP 0 and MP -3) is best explained by the sinking of phytoplankton within the estuary. An average sinking rate of 3.5 m d 179 would account for the Chlorophyll a fluxes from the upper layer (Table 2) . This is a reasonable sinking rate for netplankton diatoms (Smayda 1970) , and comparable to estimates of 2 to 4 m d in the apex of the New York Bight (Halone and Chervin 1979). Resuspension of phytoplankton from estuarine sediments may contri- bute locally to source fluxes in the lower layer, but since there is no net source flux from the estuary any such contribution must be balanced by settling out elsewhere in the lower layer. The source flux in the upper layer of the upper bay segment (MP 0 to MP -3) was unusual as the only high flow upper layer source flux and may have been an input from the ad- jacent East River (Figure 1), which is not included in the model. Since significant growth did not occur elsewhere in the estuary upper layer and there is no evidence that growth rate varied within the estuary, it is unlikely that the source flux was due to phytoplankton growth. Further- more, if the source flux was due to growth, the model fluxes imply that the average doubling times would have been 0.4 d (Table 2). This is short- er than the phytoplankton doubling times (1-2 d) reported for the lower estuary during spring (Malone 1977). Since direct measurements of exchange with the East River (Figure 1) have not been made, this question and the related question of why the source flux anomaly was absent during low flow conditions (i.e. upper bay fluxes were similar to fluxes in ad- jacent boxes) cannot be resolved. Clearly the details of Chlorophyll a circulation in the upper bay merit closer study. The pattern of source and sink fluxes during low flow was consistent with high phytoplankton growth rates during the summer, in the upper layer and high grazing rates by zooplankton in both layers. The average growth rate estimated from source and sink fluxes was 1.22 d" (Table 2). This is high but comparable to a growth rate of 1.27 d estimated from C primary pro- ductivity (Malone 1977). Estimates of potential fluxes due to copepod grazing were computed from July per copepod grazing rates in the New York Bight apex (Chervin et al. in press) and copepod abundances in the estu- ary. These estimates were in rough agreement with lower layer sink fluxes (Figure 4) . The above calcu- lations assume that copepod abun- dances and grazing rates are the same in the upper and lower layers. Any vertical variations would strong- ly affect rate estimates, and this recommends the separate sampling of each layer in future studies of estu- ary zooplankton. N0N- STEADY -STATE VARIATIONS IN CHLOROPHYLL a The above discussion assumes that source and sink fluxes were in "local" steady state, i.e. that the rate of significant variation in the boundary conditions and processes contributing to within box fluxes is slower than the response rate of the lower estuary. Generally, the response times were shorter than the weekly sampling interval and it is not known how much variation occurred on time scales shorter than 7 days. However, the time scales of phyto- plankton blooms are generally longer than the estuary response times given here. Netplankton blooms in offshore waters during winter-spring typically last 1 to 2 weeks (Malone and Chervin 1979, Malone et al. in press). Nano- plankton biomass at the upstream upper layer was fairly constant dur- ing most of the low flow period (mean 180 Table 2. Rates computed from model source and sink fluxes for high flow and low flow conditions. Box High Flow Mean Chi a Specific rates: upper layer MP to MP Upper layer Lower layer Gain Loss b,c Doubling d e Growth Time 7.0 -3.0 6.86 9.02 3.0 0.0 5.01 7.82 0.0 6.0 3.60 6.96 6.0 11.0 2.73 5.86 Entire upper layer mean sinking rate -7.0 -3.0 -3.0 0.0 0.0 6.0 6.0 11.0 11.0 18.0 6.02 4.76 4.06 4.09 4.03 Entire upper layer 0.80 0.50 0.90 (3 0.69 .5 m d ) Low Flow 6.90 0.20 0.44 5.15 0.51 0.46 3.62 1.22 1.32 2.61 0.41 0.96 1.97 0.50 1.72 0.72 1.70 1.22 0.4 0.64 1.0 0.99 0.7 2.54 0.3 1.37 0.5 2.22 0.3 0.6 Gain - source flux/total amount of Chi a in the box (i.e. Chi a concentra- tion x box volume) . Loss = sink flux/total amount of Chi a in the adjacent MP -3 to Mp -7 box. It was assumed that the loss rate in the MP 0 MP 3 upper layer was the same. "Loss = sink flux /total amount of Chi a in the corresponding lower layer box assumed to also apply to the upper layer. Growth rate = gain + loss. "Doubling time = In 2/growth rate, "Sinking rate needed to account depth difference between upper and lower layer of 5.1 m. Sinking rate needed to account for a loss rate of 0.69 d over the mean 181 4.43 yg 1 , 1 sd 1.35 yg 1 ) when growth rates are high and fairly constant (Malone 1977). A few exceptions to this overall pattern may have occurred, but their effect on means calculated over high and low flow periods should be small. Not included in above nannoplankton biomass mean are two occasions when Chlorophyll a exceeded 10 yg 1 . At these times the day to day vari- ability of Chlorophyll a was high (i.e. > factor of 2) probably as a result of downstream advection of a "patch" of Chlorophyll a from the upper estuary (Malone et al. 1980). During low flow variations also oc- curred at the lower layer boundary at MP-7 (mean Chlorophyll a 8.06 yg l" , sd 6.24 yg 1 ). These variations were probably related to inputs from Raritan Bay (O'Reilly et al. 1976), but it is not known how these inputs change with time. CONCLUSIONS AND RECOMMENDATIONS MODELING APPROACH The two-dimensional box model based on suitably averaged and cor- rected salinity data is a valuable tool for studying phytoplankton distributions in estuaries. In addi- tion to describing the essential features of two-layered estuarine circulation and interactions between estuarine and coastal waters, the model provides independent estimates of fluxes due to estuarine circu- lation and fluxes due to other pro- cesses. Flux component estimates for the lower Hudson Estuary compared reasonably with the results of other analysis. The seasonal variation in Chlorophyll a circulation was con- sistent with previous observations on the direction of Chlorophyll a transports into and within the estu- ary (Malone 1977, Malone et al. 1980). More importantly, rates of phytoplankton growth, sinking, and grazing inferred from source and sink fluxes agreed with rates calculated from experimental data. Hopefully the present success of the two- dimensional box model will motivate its application to other, similar situations . FRESHWATER FLOW EFFECTS Using the two-dimensional box model we can see the results of natural variations in freshwater flow on circulation and response times in the lower estuary. The estuarine transport and increases in response time are small compared to changes in Qf. This result probably applies to other partially mixed estuaries of fairly constant cross-sectional area, such as the James River (Pritchard 1967). However, modifications to the model to study the effect of very low Qfs will not be valid in general, since the Q at which the estuary would no longer be partially mixed and the two-dimensional box model would not apply cannot be determined by such an empirical approach. Inde- pendent estimates of salt transport at MP -7 showed a similar stabilizing tendency, in which estuarine circu- lation is maintained by increasing influx of salt as freshwater flow increased (Hunkins submitted) . In light of this stability the direct effect of changes in fresh- water flow on phytoplankton biomass in the lower estuary was small com- pared to the effects of seasonal variations in rates of phytoplankton growth and grazing within the estuary and the development of netplankton blooms in adjacent coastal water (Malone 1977, Malone et al. 1980, Malone and Chervin 1979). During both flow regimes the 182 estuary was a net sink for Chloro- phyll a though the reasons for this were different in each case. During high flow when advection from ad- jacent coastal water was the main source of Chlorophyll a, only a small percentage of the input was lost in the lower estuary (4%) (probably as a result of sinking) . The rest was re- cycled back into coastal waters (89%) or further upstream (7%) . The lower estuary was a sink with respect to both the upper estuary and offshore waters during low flow. The loss was 17 percent of total input. However, the loss was the net result of the active processes of growth (mean for lower estuary low .Jilow by above cal- culations 192 x 10 mg ChL a d~ ) and grazing (mean 239 x 10 mg Chi a d ). Thus phytoplankton dynamics changed from a passive system of advection and sinking during high flow to an active system of growth and grazing during low flow. ACKNOWLEDGEMENTS This research was supported by NSF Grant OCE 76-80883 and OCE 80- 00677. Lamont-Doherty Geological Observatory Contribution No. 3160. LITERATURE CITED Chervin, M.B. ; Garside, C. ; Litch- field, CD.; Malone, T.C.; Thomas, J. P. Synoptic investi- gation of nutrient cycling in the plume of the Hudson and Raritan Rivers. Malone, T.C. ed. NOAA Tech. Report. (in press) . Deck, B. Nutrient element distri- butions in the Hudson estuary. New York: Columbia University, 1980. Dissertation. Hammond, D.E. Dissolved gases and kinetic processes in the Hudson River Estuary. New York: Colum- bia University; 1975. 161 p. Thesis. Hansen, D. V. Salt balance and circulation in partially mixed estuaries. Lauff, G.H. ed. Estuaries. Washington, D.C.: American Association for the Advancement of Science; 1967: 45-51. Hunkins , K. Salt transport in the Hudson Estuary. Submitted to J. Phys . Oceanogr.; 1980. Ketchum, B.H. Hydrographic fact- ors involved in dispersion of pollutants introduced into tidal streams. J. Boston Soc. Civil Engrs. 37:296-314; 1967. Abood, K.A. Circulation in the Hud- son Estuary. Roels, O.A. ed. Hudson River colloquim. Annals of the New York Academy of Sciences 250:39-111; 1974. Bowden, K.F. Circulation and mix- ing in the Mersey Estuary. In- ternational Association of Sci- entific Hydrology. Committee of Surface Waters Publication 51: 352-360; 1960. Malone, T. C. Environmental regu- lation of phytoplankton pro- ductivity in the lower Hudson Estuary. Estuarine Coastal Mar. Sci. 5: 157-171; 1977. Malone, T. C; Chervin, M. The pro- duction and fate of phytoplank- ton size fractions in the plume of the Hudson River, New York Bight. Limnol. Oceanogr. 24:683- 696; 1979. Malone, T.C; Neale, P.J. Boardman 183 D.C. Influences of estuarine circulation on the distribution and biomass of phytoplankton size fractions. Kennedy, V.S. ed. Estuarine perspectives. New York: Academic Press; 1980. Malone, T.C.; Garside, C; Neale, P.J. Effects of silicate de- pletion on photosynthesis by diatoms in the plume of the Hudson River. Mar. Biol. 58: 197-204; 1980. Am. Soc. Proc. Am. Soc. Civil Engineers 95: 115-124; 1969. Quirk, Lawler, and Matusky Engin- eers. Assimilative capacity study. Albany, NY: New York State Dept. of Environmental Conservation; 1970: 38-39. Simpson, J.J. ; Hammond, D.E. Ap- plication of one-dimensional models to the Hudson River Estuary. Unpublished. Morrison, D.F. Multivariate stat- istical methods. New York, NY: McGraw-Hill Book Co. 1976: 266- 301. Noble, B.; Daniel, J.W. Applied lin- ear algebra. Englewood Cliffs, N.J.: Prentice-Hall, Inc.; 1977: 393-402. O'Reilly, J. E . ; Thomas, J. P.; Evans, C.E. Annual primary production (nannoplankton, netplankton, dissolved organic matter) in the Lower New York Bay. (U.S. Dept. of Commerce NOAA) Paper #19 McKeon, W.H. and Lauer, G. J. ed. Fourth Symposium on Hud- son River Ecology. Hudson River Environmental Society, Inc., N.Y. 1976. Pritchard, D. W. circulation estuaries . Estuaries . Observations of in coastal plain Lauff, G.H. ed. Washington , D.C: American Association for the Advancement of Science; 1967: 37-44. Pritchard, D.W. Dispersion and flush- ing of pollutants in estuaries. J. Hydraulics Division, Proc. Smayda , T.J. The suspension and sinking of phytoplankton in the sea. Barnes, H. ed . Oceanography and marine biology, Vol. 5. George Allen and Unwin; 1970: 353-414. Snedecor, G.W. ; Cochran, W.G. Sta- tistical methods. Ames, Iowa: The Iowa State University Press. 1978: 465-470. Stewart, H.B. Upstream bottom cur- rents in New York Harbor. Sci. 127: 1113-1115; 1958. Stommel, H. Computation of pollu- tion in a vertically mixed estuary. Sewage Ind. Wastes 25:1065-1071; 1953. Taft, J.L.; Elliot, A.J.; Taylor, W.R. Box model analysis of Chesapeake Bay ammonium and nitrate fluxes. Wiley, M.L. ed. Estuarine interactions. New York: Academic Press; 1978: 115-130. Tully, J. P. On structure, entrain- ment and transport in estuarine embayments. J. Mar. Res. 17: 523-535; 1958. 184 ASSESSMENT METHODOLOGIES FOR FRESHWATER INFLOWS TO CHESAPEAKE BAY C. John Klein, Owen P. Bricker, David A. Flemer, Thomas H. Pheiffer, James T. Smullen, and Richard E. Purdy Environmental Protection Agency, Annapolis, Maryland ABSTRACT The U.S. Environmental Protec- tion Agency (EPA) Chesapeake Bay program is conducting an in-depth study to assess the principal factors having adverse impacts on the water quality of the bay. The program fo- cuses on the point and nonpoint sources of pollution including nu- trients and toxic chemicals that are associated with various land use practices. Water quality data will be evaluated through use of stochas- tic and deterministic models. Field data collected on specific land uses from five test basins will be the basis for research to verify nonpoint source runoff rates. The field data will be used to calibrate and verify mathematical models in the test basins including nonpoint source loading, stream transport and estuarine processes. In particular, the estuarine models will simulate the impacts of nutrients on water quality. Fall line water quality data will serve as an independent data set to compare the point and nonpoint source projections associ- ated with various land use activi- ties . Mathematical models will be employed on a bay-wide scale to gene- rate nonpoint source loadings basin- wide and to assess the impact from those loading on the tidal bay for the present (1980) and future (2000) conditions. Several growth scenarios that include consumptive freshwater use will be evaluated for their im- pact on water quality in the bay. INTRODUCTION The Chesapeake Bay is one of the largest estuarine complexes in North America. It is a moderately strati- fied system exhibiting temporally and spatially complex hydrodynamics in both the vertical and the horizontal directions (Pritchard 1967). The bay is 195 miles long with 8,000 miles of shoreline, a surface area of (tidal estuarine system) about 4,300 square miles and a drainage basin of 64,000 square miles. The bay re- ceives drainage water from six states with the major supply contributed by the states of Pennsylvania, Maryland and Virginia (Figure 1). The Susque- hanna River supplies about 50 percent of the annual freshwater supply with the Potomac and James Rivers account- ing for another 35 percent. Because of the bay's size, its wealth of natural and economic re- sources and the need for a continued stewardship, the U.S. Environmental Protection Agency was authorized in 1976 to initiate the Chesapeake Bay Program. The program is a five-year study of the environmental quality and resources management of the bay. From a list of 10 candidate problem areas, the program initially under- took work in three technical areas; (1) toxic chemicals in the food chain, (2) eutrophication (the supply 185 Figure 1. Chesapeake Bay and its drainage basin. 186 and accumulation of excess nutri- ents), and (3) the decline of sub- merged vegetation. Recently, dredg- ing and spoil disposal were added as a fourth technical area. There is also a focus on management as a spe- cial area of study. The program has a strong focus on water quality which is inextric- ably linked with freshwater supply. The many important uses of the bay including associated living resources require that water quality and quan- tity information be an integral part of the research plan (U.S. EPA 1980). The quantity and timing of freshwater inflow to the bay is known to affect the circulation and distri- bution of salinity in the bay's waters. The salinity distribution has a fundamental relationship to the growth, reproduction and survival of the biota and to the chemistry of the bay's waters and sediments. Knowl- edge about circulation is important in specifying the distribution and characterization of pollutants and the resulting exposure of organisms to toxic chemicals and nutrients. A conceptual program framework is provided to assist in the tracking of the numerous activities that range from an analysis of loadings of toxic chemicals and nutrients to the tidal estuarine system to possible manage- ment control alternatives (Figure 2) . This paper emphasizes the modeling approach, model components, analyti- cal approach and problem assessment. Beacuse of the state of the art and the allocation of resources, more emphasis is given to water quality modeling of nutrients and their rela- tionship to the dissolved oxygen deficit than to toxic substances. All work discussed in this paper was undertaken with the intent of bay- wide application. Work in the submerged aquatic vegetation area is oriented with emphasis on the distribution and abundance of the grasses environment- al factors, e.g., light requirements and herbicide effects, ecological processes, e.g., nutrient cycling and value of the grasses as food and habitat to fish and wildlife. This work will not be discussed specif- ically in this paper except in the context of sources and transport and fate of nutrients, sediments and toxic chemicals within the bay sys- tem. OBJECTIVES NUTRIENTS The objectives of the eutrophi- cation program are: (1) To determine the state of the bay with regard to nutrient enrichment, past and pres- ent, (2) to quantify the nutrient levels in Chesapeake Bay based on water quality standards, non-degrada- tion and water quality enhancement for years 1980 and 2000, and (3) to evaluate nutrient control alterna- tives for achieving and maintaining acceptable nutrient levels in the Chesapeake Bay at present (1980) and in the future (2000). As referenced above, the second objective of the eutrophication pro- gram is to quantify nutrient loadings to the Chesapeake Bay from various sources. In order to achieve this important objective, current research is directed toward: (1) assessing point source information on municipal and industrial sources, (2) compiling statistics on land use and population trends in the bay basin, (3) measur- ing nutrient loadings from the major tributaries to the bay, (4) estimat- ing nutrient fallout from the atmos- phere, (5) verifying nonpoint source 187 are some troubling discrepancies between the Texas commercial land- ings data reported by Chapman (1966) and those presented by Armstrong (1980). The differences are not due to a 14 year lag in sampling years, be- cause the data discussed by Armstrong (1980) were first presented by Cope- land (1966) and may, in fact, be part of the same data set (1956-62) used by Chapman (1966). If the numbers reported by Chapman are too high, particularly the 450 kg/ha assigned to Galveston Bay, then his argument for a positive relationship between freshwater input and fisheries yield is not very compelling. It seems clear that while there may be some estuaries in which there is a good correlation (either posi- tive or negative) between freshwater discharge and fisheries yield, the mechanism involved is probably some- thing other than a simple fertilizing effect of the river itself (eg. Huntsman 1955; Barrett and Ralph 1977; Sheridan and Livingston 1979). In fact, considering all of the fac- tors that go into determining the catch of finfish and shellfish in an estuary, it is remarkable how similar the area-based yields are from most coastal marine systems. SEASONAL CYCLES There appear to be few systems in which the seasonal cycle in pri- mary production corresponds with the cycle of river discharge (Figure 8). With the exception of Narragansett Bay and perhaps a few other areas which have a strong winter-spring phytoplankton bloom, the general pattern seems to be for production to peak during the summer, some months after river discharge has de- clined following spring runoff. Be- cause the freshwater usually carries sediment with it, the offset in pro- duction may be due to decreasing turbidity as salinity rises or to a combination of increasing solar radi- ation and temperature (Figure 8) . In the case of Narragansett Bay, the freshwater input is very small and initiation of the winter-spring bloom has been shown to be due to light and other factors rather than to river discharge (Hitchcock and Smayda 1977; Nixon et al. 1979) . It is possible to examine the potential contribution of freshwater nutrient inputs to the spring-summer phytoplankton bloom in a more general way. As river (or groundwater) flow increases, fresh water will accumu- late in the estuary, and the salinity will decrease. As noted earlier, the annual salinity excursion for many estuaries appears to fall around 5 o/oo to 10 o/oo (Figure 5). A sa- linity decline of 5 o/oo will repre- sent an accumulation of varying amounts of fresh water, depending on the salinity of the nearshore and es- tuarine water with which it is being mixed (Table 4). If the concentra- tions of dissolved inorganic nitrogen (the major limiting nutrient in coastal marine waters) in the river water lie between 10 to 100 yM, the amount of river-borne nitrogen per unit volume of lower salinity estu- arine water can be calculated and an estimate made of the primary produc- tion this amount of nitrogen could support (Redfield 1934). The result suggests that in most estuaries the accumulation of "new" nitrogen from fresh water is not likely to support more than a few days of growth under bloom conditions when production rates often reach or exceed 500-1000 mg C/m /day. But the total primary production cannot be calculated with- out a knowledge of the turnover rate and residence time of the nitrogen in the estuary. 188 feco lu \a so UJ UJ z£ > HO zO So (OQ (A UJ Z o 0. 5 O O 1- , Z w LU LU ^O LU LU Oh << MAN STR _i 1 O 1 « pa CU « 0) Oh <8 to 01 U CO 0J 00 CD •u CO S-l 4-1 CO CI 0) s UJ 60 CO C CO E 00 CI •H & O i—l > OJ •d u o U o s OJ E (0 S-l tH m a 4-» UJ o c o u CN 4J s- 3 00 •H 189 runoff from data collected on five test drainage basins in Pennsylvania, Maryland and Virginia, and (6) cali- brating and verifying mathematical models to include nonpoint source loading models, stream transport mod- els and estuarine response models. studies will provide a baseline des- cription of the estuarine system against which future changes can be measured. The overall goal of the toxics program is to provide a sound scientific foundation on which ef- fective strategies can be built. TOXICS The Chesapeake Bay Toxics Program has been designed to address a number of problems associated with the estuarine environment. Two of the greatest threats to an estuary are sediments and toxic materials. Sediments tend to fill in estuaries and toxic materials adversely impact the estuarine biota. These two fact- ors are studied together since the majority of heavy metals, radio- nuclides and organic toxic chemicals, are known to adsorb to fine grain particles both in the water and sedi- ments. To assess the impacts of these materials, the toxics program is pursuing research on the pres- ent distribution of sediments and toxic materials to the bay, and the behavior and fate of sediments and toxic materials within the bay. The first area of investigation will provide data about what toxic chemi- cals are in the system now, where they are located and their form (e.g., inorganic, organic, etc.). The second area of investigation will document the types of materials en- tering the bay, the various sources of these materials (natural and anthropogenic) , and will provide a first estimate of the rates of addi- tion to the estuary. The third area of investigation will delineate the routes and mechanisms of transport of sediments and toxic materials within the estuary, the sites of ac- cumulation (sedimentation), the chemical behavior (mobilization and cycling) and will begin to identify biological impacts. Together, these COMPONENTS OF METHODOLOGY FALL LINE MONITORING Through an interagency agreement with the EPA Chesapeake Bay Program, the U.S. Geological Survey is con- ducting a two-year intensive study at the fall line of the major rivers draining into the tidal Chesapeake Bay. The Susquehanna, Potomac and James monitoring sites are located at Conowingo, Maryland (dam and Rt. 40 bridge), Washington, D.C. (Chain Bridge), and at Cartersville , Vir- ginia, respectively. Measurements are being made for suspended sedi- ment, nitrogen, phosphorus, carbon, trace metals, pesticides, sulfate and major ions, chlorophyll a, total solids and freshwater discharge. Physical parameters are measured daily with nutrients and metals be- ing monitored monthly (twice a month for Susquehanna). In addition, high- flow sampling over the hydrograph is being carried out to assess the im- pact from upland nonpoint source run- off. The products of this study in- clude estimated input loadings to the bay of suspended sediment, major dissolved species, selected nu- trient species, and trace metals, plus a seasonal characterization of pesticide runoff. Levels of con- fidence will be made by the United States Geological Survey (USGS) for the various loading curves. These field-measured loadings will be in- troduced into the bay-wide water quality model for calibration and 190 verification purposes. Also, the USGS will compare its loading data with historical data to note any trends in loadings to the bay from the major tributaries. An interim data report of the USGS effort is now available (Lang and Grason 1980) . POINT SOURCE INVENTORY The bay program will make esti- mates of municipal and industrial point source loadings from existing EPA and state agency files. Mason and McFadden (1980) reported that the EPA Waste Water Systems Inventory Survey is the best available data base for municipal point source dis- charges. This survey provides treat- ment plant flows for the present and projected design flows of municipal plants. Information is available for 1978 (actual) and year 2000 (pro- jected) effluent concentrations of phosphorus, ammonia, total Kjeldahl nitrogen, and total nitrogen for all municipal point sources in the Chesa- peake Bay basin with flows in excess of one million gallons per day. The most up-to-date and accurate informa- tion will be utilized during model calibration and verification and for all model production runs. INTENSIVE WATERSHED STUDIES A set of intensive watershed studies is being conducted to char- acterize runoff pollution loadings and to facilitate projections of non- point source loads in the Chesapeake Bay basin. The approach is to iso- late small study sites which exhibit relatively homogeneous land use, geology, soils, topography, land surface maintenance practices, etc. These factors and others are being related to the nonpoint source load- ing regime observed during monitor- ing periods to characterize runoff water quality by quantifiable land and land use parameters. The tech- nique of intensive monitoring of small watersheds was chosen because it represents the state of the art of runoff pollution assessment. The intensive watershed studies are in- tended to identify the specific sources of runoff pollution loads and also to identify some of the physical characteristics that determine the responses of each source to hydro- meteorologic inputs. When the data are linked with appropriate water quality assessment tools, they will allow an assessment of the water quality impacts of present and fu- ture land use changes and provide the potential for the control of runoff loadings through the application of Best Management Practices (BMPs). Presently, nonpoint monitoring programs have begun in the Occoquan River (9 sites) and Ware River (4 sites) watersheds in Virginia and the Pequea Creek basin (5 sites) in Pennsylvania. Similar studies are scheduled to begin this summer in Maryland watersheds (14 sites). Sites have been selected to represent a variety of land uses (18 Agricul- tural, 6 Forested, 6 Residential, 2 Mixed), soils, and geologic forma- tions as well as various other para- meters, e.g., slope. These sites are being monitored during both base flow and storm event conditions for a variety of pollutant constituents. In addition, the performances of several nonpoint pollution control measures are being evaluated. Measures of various land, land-surface and cul- tural parameters are being documented on each site for use in later charac- terization efforts to be made through the use of a deterministic computer- based hydrologic, water quality model . 191 ATMOSPHERIC INPUT Atmospheric deposition of ma- terials in the form of wet fall and dry fall has been identified as a significant source of metals and cer- tain organic compounds to the Great Lakes. In order to determine the importance of atmospheric inputs to the Chesapeake Bay, a network of ten sampling stations fringing the bay has been established. At each sta- tion, both wet fall and dry fall will be continuously collected using Aero- chem Metric model 301 samplers. Ex- tensive chemical analysis will be performed on all of the samples for inorganic constituents, and on se- lected samples for organic compounds to provide an assessment of the types and amounts of materials contributed to the estuary from the atmosphere. partition coefficients, as a measure of bioaccumulation potential. The toxic screening protocol is being developed for the states of Maryland and Virginia under contract with the Monsanto Research Corporation. The toxic chemical identifica- tion involves the use of gas chroma- tograph/mass spectrometer procedures which are compatible with those of Dr. Robert Huggett of the Virginia Institute of Marine Science who is measuring toxic organic chemicals in sediments and benthic biota from the bay. Both procedures utilize compu- ter capability to identify specific compounds and to store the data base and "finger-prints" of unknown chem- icals for future reference. BASELINE SEDIMENT STUDIES POINT SOURCE ASSESSMENT Two approaches are being used to obtain data on toxic chemical load- ings from point sources to the bay. The first approach utilizes informa- tion available from the National Pollution Discharge Elimination Sys- tem permits. From these permits es- timates can be made on the volume of industrial discharges to the bay. Knowledge of industrial chemical processes will give information on the expected kinds of chemicals and a first order estimate of their effluent concentration. The second approach is also qualitative. It involves the identification of a wide range of toxic organic chemicals as part of a toxic screening protocol. Approximately 30 effluents will be examined from plants discharging effluents into the bay and its tidal tributaries. The work includes chem- ical analysis of the effluents, the development of a set of bioassays and the application of octanal/water The Chesapeake Bay Program is conducting an intensive survey of the physical, chemical and biological characteristics of the sediments of the Chesapeake Bay estuary. Surface sediment is being sampled on a kilo- meter grid in the Maryland portion of the bay and on a 1.4 kilometer grid in the Virginia portion of the bay. The surface sediment samples are be- ing analyzed for particle size dis- tribution, and the content of water, carbon and total sulphur. Maps por- traying these parameters are in prep- aration. In addition, maps showing the areas of sediment accumulation and erosion on the bay bottom have been compiled. Rates of sedimenta- tion have been determined independ- ently using Pb geochronology and pollen biostratigraphy . A set of surface sediment samples and cores (1-meter depth) from selected transects across the bay has been analysed for a suite of trace metals. Interstitial water chemistry has been investigated in 192 in the upper meter of sediment at stations from the mouth of the Sus- quehanna River to the Virginia Capes on a seasonal basis. These data per- mit calculations of the benthic flux of nutrients and trace metals from the bottom sediment to the estuarine waters. At the same locations, box cores have been collected for benthic infaunal investigations. The inte- gration of the physical and chemical characteristics of the sediment with the benthic infaunal biota will pro- vide better understanding of the role of bottom sediments in estuarine processes . EXISTING CONDITIONS IN BAY BAYWIDE SURVEY The hydrodynamic field survey was designed to provide a data set with which to construct and verify a numerical model of the Chesapeake Bay. The aim was to provide a one-month measurement series of the circulation and driving forces of the Chesapeake Bay System to include: temperature, salinity, current, tide stage, freshwater inflow and meteo- rological measurements. Seventy current meters were moored throughout the bay during the month of July. Nearly half of the current meters had salinity and tem- perature recording capability (pri- mary moorings). The mouth of Chesa- peake Bay between the Virginia Capes was the most heavily instrumented, in order to obtain an estimate of the inflow and outflow of the estuary. Instruments were also concentrated on the Cape Charles City - Mobjack Bay transect because of the unique cir- culation features which have been demonstrated in this area (Figure 3) . The Smith Point - Tangier Sound section was designed to measure the outflow from the Potomac as well as the interaction of the Tangier Sound water masses with the bay proper. Single moorings were deployed off Chesapeake Beach, at the Bay Bridge and north of Pooles Island in order to coordinate with the intensive in- formational base that already exists from previous Chesapeake Bay studies. Additional primary moorings were provided by the United States Geolog- ical Survey in the Potomac River and by the Maryland Water Resources Administration near the mouths of the Chester and Patuxent rivers. Two wind speed and direction recorders were placed on the lower eastern shore of the Chesapeake Bay to fill in the sparse distribution of National Weather Service meteorologi- cal stations that now exist for the bay area. In addition, two tide sta- tions were established on the lower eastern shore, because this area was not covered adequately with tide gages. A comprehensive set of nutrient data for Chesapeake Bay and its trib- utaries was collected during the pe- riod of July 9-16, 1980. This data set will characterize boundary condi- tions for the bay (bay mouth and tributary mouths) and will also in- clude several transects across the bay. Water movement data, as well as temperature, salinity, chlorophyll a, dissolved oxygen, suspended sediment and nutrients (particulate, dissolved and total nitrogen and phosphorus silicate, ammonia, nitrite, nitrate, organic forms of nitrogen) were col- lected at thirteen bay transects for the purpose of mass balance and mod- el verification. Sampling at bay transects was performed twice a day at each depth where a current meter was recording water movement. Also, during the eight-day, July field study, sampling was conducted at three-hour intervals for thirty-six 193 Figure 3. Moored instrument array positions, June - July 1980. 194 hours along the transect at the mouth of the Chesapeake Bay. This 36-hour intensive survey was critical to es- tablishing the previously undefined boundary at the mouth of the bay both for nutrients and hydrodynamics. The set of bay-wide nutrient data collected during the July inten- sive survey will be used to verify a predictive water quality model of the tidal Chesapeake Bay. In order to make the model function properly, model coefficients or rates must be determined and then read into the model's computer code. These model values will be obtained from the July data as well as from experiments carried out this May and August by bay research institutions. Examples of these model rates are grazing coefficient for zooplankton, benthic dissolved oxygen demand, light ex- tinction coefficient and ratios of N and P to chlorophyll. The model selected for application to the bay is the model developed by Dr. H. S. Chen of the Virginia Institute of Marine Science. ANALYTICAL APPROACH WATER QUALITY MODELING The need for mathematical de- scriptors of the processes which in- teract to generate the trophic condi- tion of the Chesapeake Bay system was reflected in the CBP Eutrophication Work Plan of late 1977 (Pheiffer et al. 1977). The plan called for the selection of water quality assessment tools which would develop loads from the tributary basin and "translate material loads into eutrophication levels." Many predictive models of storm runoff pollution have been developed and reported in the literature over the past decade. They range from complex, computer-based models of rainfall/washoff to a simple statis- tical relationship between streamflow (or runoff) and aerial pollutant yield rates. Modelers generally classify the former (complex) type as deterministic models and the latter (simple) as parametric models. The trade-offs between these two general classes of modeling approaches have been described as an inverse rela- tionship between the risk of not representing the system versus the difficulty in obtaining a solution (Figure 4). In other words, the level of effort involved with the set-up, calibration, verification and production utilization of a model should be justified by the level of significance required of the results, the quality and extent of the cali- bration/verification data base and, above all, the availability of the resources necessary to perform the work (Smullen 1980). The level of modeling selected for the non-tidal drainage basin of Chesapeake Bay is referred to as HSPF or Hydrological Simulation Program in FORTRAN. This state-of-the-art mod- eling package was developed by EPA Environmental Research Laboratory at Athens, Georgia. The HSPF model is a continuous simulation model which simulates the movement of water and associated pollutants on land sur- faces as well as the dispersionary and flow characteristics of conserva- tive and non-conservative constitu- ents in branching stream systems and rivers. Constituents modeled include conservative minerals, temperature, BOD, chlorophyll a, organic and or- tho-phosphorus, ammonia, nitrate, ni- trite, dissolved oxygen and coliform bacteria. It also considers nutrient cycles, zooplankton and algal growth. The work plan proposed to be implemented under the EPA/Northern 195 ^LLI I • ^ H B& X 2 LU o _l DL 3= O 2 S O CD o 1- 1 ■* CD k. 3 O) 196 Virginia Planning District Commission Cooperative Agreement has three major components (Hartigan 1980). The first component will be a comprehen- sive analysis of the hydrologic and nonpoint source nutrient loading data collected by the investigators for the Pequea, Chester, Patuxent, Occoquan and Ware sites. This 50 to 60 station-years of data will then be used to develop, using continuous simulation model calibration tech- niques, transferable land use, non- point pollution relationships for application to the entire Chesapeake Bay drainage basin (approximately 64,000 square miles). The second component will be the actual calibration and verification of the HSPF model to the entire drainage basin. This basinwide model will be segmented to provide suffi- cient loading information to account for point and nonpoint sources of nutrients at the fall lines (Susque- hanna, Potomac and James) yet not so detailed that computer costs for long-term simulations would be pro- hibitive. The third component of the pro- posed effort involves the modeling production run phase. The verified basinwide model will be run to pro- duce time series output. This output will then be analyzed to generate loadings, based on existing (1980) and future (year 2000) land use pat- terns for the entire bay. These loading data are an essential input to a bay-wide water quality model of the tidal Chesapeake. The bay-wide model covering the bay proper to the head of tide will be employed to identify water quality problem areas based upon fall line loading information. The work will be performed by the Virginia Insti- tute of Marine Scince (VIMS). The approach will be to adapt an existing water quality model to the entire tidal portion of the Chesapeake Bay. The model will not only address the effects of a particular loading scenario, but will be used in an iterative fashion to determine neces- sary fall line loadings given a par- ticular bay water quality condition. The model is a two-dimensional, depth averaged, finite element, real time, hydrodynamic , water quality model developed by H.S. Chen at the Virginia Institute of Marine Sciences. The hydrodynamic portion of the model incorporates hydrologic as well as meteorological and astronomi- cal effects. The water quality com- ponent addresses the following constituents: phytoplankton, organic nitrogen, ammonia nitrogen, nitrite- nitrate nitrogen, organic phosphorus, inorganic phosphorus, carbonaceous biochemical oxygen demand and dis- solved oxygen deficit. In general, the model simulates primary pro- duction and its resultant affect on dissolved oxygen concentrations with constants for zooplankton grazing and sediment to water column fluxes of nutrients . The limiting constraint in using a depth-averaged model is the loss of vertical resolution. This problem is negligible when mixing causes surface to bottom exchange of water mass re- sulting in a uniform concentration throughout the water column. How- ever, when pressure gradients are strong and stratification is exhibit- ed, dramatic changes in surface to bottom concentrations are possible. It is the latter case in which a better resolution of the problem is needed. The problem becomes one of test- ing the validity of depth averaging in areas delineated as having a dis- solved oxygen problem. In order to accomplish this, a three-dimensional 197 real time hydrodynamic model is being developed by Camp, Dresser and McKee . This model, like the VIMS model, is also a finite element model. The model will be used to investigate the nature of the hydrodynamics in areas determined to have a dissolved oxygen problem using the VIMS model. If vertical mixing cannot be assumed, then the depth averaged concentration will be vertically profiled using historical data. The key indicator used in this approach to define the existence of a eutrophication problem will be dis- solved oxygen concentrations. In order to assess possible biota effects as the result of depressed DO concentrations, an indices approach will be taken. A preliminary report on selected and developed indices for use in the detection, measurement and assessment of estuarine nutrient en- richment was prepared in October of 1979 by the Chesapeake Research Con- sortium and will be used for this purpose. TOXIC RISK ASSESSMENT As a final component of the pro- gram, the toxic chemicals of concern will be subjected to a risk analysis. These chemicals are being identified in the sediments , water and selected biota of the bay and from effluents that enter the bay. Considerable background data are being developed on the sources, loadings to the tidal estuary and transport and fate of toxic chemicals in the bay. This information will be used to develop an exposure assessment model which will estimate the concentration of a toxic chemical at a specified loca- tion and time to the extent possible in the estuary. This model, coupled with information on toxicity of specified compounds to selected organisms and knowledge about the distribution and abundance of organ- isms, will be the basis for the risk assessment. Three levels of risk assessment are to be used. All chemicals of concern will be evaluated by the automated methods which constitutes level one. Lists of toxic chemicals will be compared to the chemicals of concern. Chemical Abstract System (CAS) numbers will be used in the searches. The lists of chemicals will include the proposed and estab- lished water quality criteria chem- icals and other lists of chemicals from various resources which include toxicity data that can be easily stored on a computer system. Only select chemicals will be evaluated by the second level of risk assessment. The second level involves a thorough literature search and review for select chemicals of concern. When data are still deficient and/or there is reason for extra concern, then the third level of assessment will be in- cluded. The third level involves a structure-activity relationship ap- proach. The structure-activity rela- tionship approach invlolves the generation of analogs and/or metab- olites followed by a literature search and review of these compounds. Principles of chemistry and toxi- cology are used to evaluate the literature data and to estimate the hazard of the chemical of concern. SUMMARY The bay-wide methodology as presented here characterizes the system as to what is coming into the system, what is currently in the system, how it moves about within the system and an approach to assess its impacts. In the toxics as well as the nutrient program areas, the framework is to identify the present 198 distribution, current impacts and behavior and fate of toxics and nu- trients. This information will pro- vide a baseline description of the estuarine system against which future changes can be measured, and possible control measures assessed. Program. U.S. E.P.A. 68-01-4144; 1980. Contrib. PREFERENCES Hartigan, J. P., Jr. A modeling study of nonpoint pollution loadings and transport in the Chesapeake Bay basin. Work Plan of North- ern Virginia Planning District Commission; 1980. Lang, D.J.; Grason, D. 1980. Water quality monitoring of three ma- jor tributaries to the Chesa- peake Bay - interim data report. U.S. Geological Survey Water Resources Investigations; 1980: 80-78. Mason, B. J. ; McFadden, J.E. Landuse and point sources in the Chesa- peake Bay Study area. Annapo- lis, MD: U.S. Environmental Pro- tection Agency, Chesapeake Bay Overton, D.E.; Meadows, M.E. Storm- water modelling. New York: Aca- demic Press; 1976. Pheiffer, T.H. et al. Eutrophica- tion work program for Chesapeake Bay; 1977. Report of Eutroph- ication Work Group. Pritchard, D.W. Observations of cir- culation in coastal plain estu- aries. Lauff, G. ed. Estuaries Washington, DC: American As- sociation Advancement Science. 1967: 37-44. Smullen, J.E. A water quality assess- ment methodology for the Chesa- peake Bay watersheds. Working Paper, Chesapeake Bay Program, EPA; 1980. U.S. Environmental Protection Agency, Office of Research and Develop- ment. Research Summary, Chesa- peake Bay. 1980; EPA-600/8-80- 019. Water Quality of the Upper Great Lakes, IJC Report to the Govern- ments of Canada and the U.S., May 1974; 91 p. 199 CHAPTER 2 RESTORATION OF FRESHWATER INFLOW TO AN ESTUARY IN CONJUNCTION WITH URBAN DEVELOPMENT 200 HISTORICAL BACKGROUND AND OVERVIEW OF PLAN FOR RESTORING FRESHWATER INFLOW TO AN ESTUARY IN CONJUNCTION WITH URBAN DEVELOPMENT Paul Larsen Larsen and Associates Miami, Florida ABSTRACT The Marco Island development proceeded concurrently with changing wetland regulations. Permits to con- struct sold lands were denied. The developer has proposed a substitute plan calling for development of 1,500 acres of uplands and 2,500 acres of wetlands located near the estuary. A key feature of the new plan is the proposed restoration of freshwater inflow to fringing estuarine wetlands impacted by prior construction of roads and drainage works. Technical reports upon which this plan is based are presented. BACKGROUND AND STATUS OF ORIGINAL DEVELOPMENT PLANS Marco Island is located in a mangrove estuarine area on the south- west coast of Florida approximately 10 miles south of Naples, 100 miles due west of Miami, and 20 miles northwest of Everglades National Park (Figure 1). When the Marco Island project started in 1964, State and Federal regulations encouraged the development of waterfront communities in mangrove areas. Initial plans called for dredging and filling large portions of the 19,500 acre original ownership area (Figure 2) . The ini- tial phase of the overall 19,500 acre plan consisted of Marco Island itself (7,000 acres). Dredge and fill per- mits to construct the first 22 per- cent (1,550 acres) of the island were routinely granted in 1964 by State and Federal agencies. In 1969, the Corps of Engineers approved the com- pletion of the next 31 percent (2,200 platted acres) of the community. Because in 1969 over 75 percent of the Marco Island lots were already sold, the Corps acknowledged the con- tinuing sale of lots on the remaining 47 percent (3,300 platted acres) of the island. They also acknowledged continuing sales in a 2,500 acre new- ly platted mainland area known as the Collier-Read tract. To accomodate new regulatory concerns, however, the Corps and the developer agreed that no additional lots would be sold on 10,000 additional unplatted acres until after all development permits were obtained. In 1972, according to new State regulations, the Governor and Cabinet of the State of Florida formalized an environmental agreement with Deltona. In return for State approvals to com- plete the development of Marco Island the developer agreed to deed over 4,000 acres of mangrove wetlands and 201 FIGURE 1 LOCATION 202 co z < -J a. LU Z a. o -J lu > u a a in co > m a CO co < co z < _l 0. Z III 2 a. o -I III > III Q E O CO < III £ < 111 Z a. o -I 111 > 111 a co o o 111 z E o < III > CO s o 111 a CO o 111 a E a. a ""3 H z E III a. o ui ui a CD Q _l o co CO a E ui H ^ w < Q. UI E u. 1- < O Z H z o UJ Z 111 z UI a 3 o > > UJ u. UJ a '•■ 203 estuarine bay bottoms into State ownership. In 1974 the developer satisfied new requirements of Federal law and received water quality certi- fication for the remaining unpermit- ted canals on Marco Island. In 1976, the Corps relied on 1975 regulations to grant permits for 16 percent (1,120 platted acres), and to deny permits for the remaining 31 percent (2,170 platted acres) of the Marco Island plan (Figure 2). OVERVIEW OF REVISED DEVELOPMENT PLANS Shortly after the 1976 Corps decision, the developer purchased three sections of lands immediately north of his original ownership. Vegetation mapping and ecosystem analysis of the entire unpermitted ownership began (Figure 3). At the same time urban planners started work on a development plan that aimed to achieve many objectives. A. The maintenance of the estuarine ecosystem required preser- vation of essentially all estuarine bays and surrounding mangrove areas. Freshwater inputs to the estuary had to be maintained or enhanced. B. Attractive substitute wa- terfront lots had to be provided for customers denied their lots by the Corps in 1976. C. The project had to mitigate the financial losses resulting from the 1976 denials. Therefore, addi- tional residential units beyond those specifically denied had to be includ- ed in the plan. D. The new project had to be linked to the existing Marco communi- ty for marketing purposes and for efficiency in providing community ammenities such as transportaion, potable water, sewer, emergency ser- vices, commercial and business areas, education facilities, recreation, health care. The resulting revised plan of de- velopment for Deltona's 17,000 acre Marco ownership is restricted to 4,000 acres comprised of 1,500 acres of uplands and 2,500 acres of interi- or wetlands. The remaining 13,000 acres of wetland ownership will be preserved (Figure 4) . RESTORATION OF FRESHWATER INFLOW TO THE ESTUARY Inland from the Marco estuary the topography is flat with eleva- tions rising at approximately one foot per mile. Before railroads, highways, agriculture, and large scale inland land development, the water table was near the ground sur- face and extensive areas were flooded for portions of the year. Freshwater flows to the estuary were the gradual and steady result of surface sheet flow and ground water movement fed by a large interior basin (Figure 5). Aerial photos, on-site inspec- tion, and government publications (McCoy 1972; Carter et al. 1973; Swayze and McPherson 1977) show that surface flows from interior areas northeast or "upstream" of the proposed development site have been altered by land development drainage, agricultural irrigation and drainage, and road and barrow ditch construc- tion. These factors have lowered the water table and short-circuited surface flows directly to the estuary . 204 FIGURE 3 VEGETATION MAP FOR UNRESOLVED OWNERSHIP AREA SCALE IN MILES 205 FIGURE 4 REVISED DEVELOPMENT PLAN FOR UNRESOLVED OWNERSHIP AREA SCALE IN MILES 1 — 206 Hi O < z < oc o a iu N 3 in z z < z u ILI V) iu cc a. iu E 3 a a < z < oc Q o iu IU z (A < Z 5 s o rS " VJU-. ■ X HJ 1 : : \ ^B^r o , . jT\ffy £ « C J ■i X 3 y - A * ' (A ^& 207 Drainage patterns on and immedi- ately adjacent to the proposed Unit 24/Unit 30 development site were al- tered by early (1926) railroad con- struction, early highway construction (Belle Meade grade) , drainage ditches (adjacent to State Road 92 and Port au Prince subdivision), golf course and airport construction, and by agricultural drainage practices. On a local basis these factors raised the water table in some areas creat- ing probable vegetation changes from saline to fresh. In other areas these factors channelized surface and groundwater flows directly to the estuary resulting in certain fringing estuarine areas being cut off from historical freshwater flows. In addition, the channelized flows changed the timing and quality of freshwater inputs to the estuary. The proposed plan for restoring freshwater inputs to the estuary is based upon blocking all channelized flows that presently leave the site. Real estate lakes will be constructed in uplands and in impacted freshwater wetlands immediately upgradient from the estuary. Lake excavation mater- ials will be utilized to fill adja- cent areas for roads and dwellings. A low levee will isolate the lake from the estuary. Water levels in the lake will seasonally vary between +1.5 and 2.0 (NGVD) duplicating pre- sent water table fluctuations. The lake will be fed by rainfall, surface runoff from adjacent development areas, and by groundwater inflow. The lake will discharge by evapora- tion, groundwater outflow, and over adjustable weirs to spreader ditches which will overflow into preservation estuarine wetlands. Freshwater out- flow from the lake will thus be de- livered to the estuary via sheet flow across preservation wetlands. Up- gradient surface flows from offsite will be routed via grassed swales around the development and supplied to spreader ditches and then via wetland sheet flow to the estuary (Figures 6 and 7) . In this particular area of Florida there is a natural berm near the water's edge. This berm causes shallow impoundment of extensive areas. The berm is overtopped by high spring tides. The shallow im- pounded area is therefore filled by rainfall, surface runoff from upgra- dient, and by overtopping spring tides. Surface discharge from the man-made lake will be supplied via spreader ditches into this shallow natural impoundment. Slow migration across this impounded area to the estuary will allow polishing and treatment of outflows prior to arrival at the estuary. All the real estate lakes will be interconnected allowing the flexi- bility of routing surface discharge to the adjustable weir and spreader ditch immediately upgradient from particular fringing wetlands that can be improved by freshwater inflow. The lake system is designed to ini- tially retain a 100-year, 24-hour storm. Weirs will be adjustable to allow subsequent discharge over a protracted period thus simulating historical freshwater inputs to the estuary. During dry periods ground- water inputs to the lake will be rou- ted to spreader ditches and then to wetland surface flow instead of lost to drainage ditches as at present. CONCLUSION This project is not intended to set a precedent for wetland develop- ment. The goal is to achieve a com- promise where changing government regulations have halted an ongoing project. Development of 1,500 acres of uplands and 2,500 acres of 208 o 111 U uj < -I £** « CO UJ CO O o < o a. >■ H 209 < w K < -I < a 11) s > a a > o z o « < tij ce LU w a o _i (0 -I < oc < o 111 < a oc u < z u (0 4 HI * < < a > a -1 a < -i z o o s UJ OC 3 a o o UJ < _i 1- o UJ o CO (0 o z oc a 3 y X t- *• < CM 2 t- UJ z z u 3 (0 210 interior wetlands is planned. A key feature of the plan is hydraulic de- sign to restore freshwater inflow to fringing estuarine wetlands impacted by prior construction of roads and drainage works. The following sec- tions of Chapter Two provide techni- cal information upon which this plan is based. LITERATURE CITED Carter, M. et al. Ecosystems analysis of the Big Cypress Swamp and estuaries. U.S. Environmental Protection Agency, Region IV; 1973. A. Floral Description of Marco Shores Development Site. Eric Heald. B. Meromixis in a Coastal Zone Excavation. Charles M. Courtney. C. The Ground Water Flow Sys- tem in the Vicinity of Marco Island, Florida. Vincent P. Amy. McCoy, J. Hydrology of western Collier County, Florida. Pre- pared by U.S. Geological Survey for the State of Florida Depart- ment of Natural Resources; 1972 Report of Investigations No. 63. D. Surface Water Flow from a South Florida Wetlands Area. J. van de Kreeke and Ernest Daddio. E. Water Budget and Projected Water Quality in Proposed Man-made Lakes near Estuaries in the Marco Island Area, Florida. Wayne C. Huber and Patrick L. Brezonik. Swayze, L; McPherson, B. The effect of the Faka Union Canal System on water levels in the Faka- hatchee Strand, Collier Coun- ty, Florida. U.S. Geological Survey Water Resources Investi- gations 77-61 prepared in coop- eration with the National Park Service; 1977. 211 FLORAL DESCRIPTION OF MARCO SHORES DEVELOPMENT SITE Eric Heald Program Director Tropical Bio-Industries Development Co. Miami, Florida The proposed development tract covers the land lying between Macllvaine Bay in the south and the old "Belle Meade Grade" in the north and extends 4,827 m from east to west. The western boundary is State Road 951. The tract includes some farmed land in the northeast corner, a golf course and airport, and an excavated lake known as Lake Marco Shores . The flora of the tract was exam- ined from the air and on the ground in October and November 1976. Aerial photography from 1962 and 1974 at a scale of 2.54 cm = 304.8 m was used to locate various large-scale plant associations. Ground observation confirmed the photo registry and was used to describe details of plant cover not evident on the aerials. Exotic plants such as Melaleuca and Brazilian pepper were largely absent from this tract. Fire has had a se- rious effect on the plants and soils of the tract as evidenced by numerous burnt out hammocks and pine stands. The results of the study are present- ed in Figure 1 and Table 1 which pro- vide a map and list of visually domi- nant plant groupings and also by Figure 2 which subdivides the area according to duration of flooding. To interpret Figure 1 , associa- tions or features have been lettered according to the following key: A - Pineland associes; B - Pine barrens; C - Swale with mixed grasses, rushes and scrub buttonwood; D - Eleocharis (tall phase) and freshwater man- groves; E - Eleocharis (short phase) and freshwater mangroves; F - Pot- hole ponds; G - Chara ponds; H - But- tonwood hammocks and strands on "Gandy peat" soil; I - West Indian hardwood hammock; J - Cresent Lake; K - Red mangrove berm that experi- ences daily tidal influence; L - Man- grove impoundment and possible weekly tidal; M - Farmland; N - Impacted tidal creek system; 0 - Golf course and airport; P - Lake Marco Shores; Q - Polyhaline mangrove; R - Fresh- water red mangrove forest; S - Black rush (Juncus roemerianus) ; T Fimbristylis-Spartina . The present mangrove and emer- gent vegetative associations north of the main east-west levee extension are depositing their leaf, seed and twig fall in situ and this is leading to a rapid elevation of soil pro- files. The Water Surveillance Branch for Region IV of The U.S. Environ- mental Protection Agency (USEPA) , has collected field data on water quality and primary production in this area (Cavinder 1979). In pure Eleocharis stands they found a live standing crop biomass of 295 g/nu (ash free dry weight) with 136 g/m of dead material. The accretion of material within the marsh has been hastened by a heavy growth of Chara in the permanent open ponds. The USEPA and Courtney (1979) have re- ported high rates of respiration 212 i— o 4-J L- ■— i/i Q. TO to E ^ — O E OJ C> U cn TO c S- ■TO E to to C u. l/l TO i~ t- TOl 3 o O EICX 1/1 X sz U T3 Q TO TO C Q to o TO M i- CL o i — •p- TO Q c r— JZ JZ 3 o 1- CL <_) CC U ► -■ TO O 1- r— Ol i/i »r- nl TO T3 TJl'r- C r— TO TD Q. 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TO tA CL L- "O i/l o E a. at c to C7i30CCJZiajTO L- jz-'-i — 4-jl-l. cE Dim l/i_oo-i/iatati-/''~TOa) *oi/i 3C i^_4_nj>r— C 1-TOQJ L-r-CJZL-L-E •— ■•- O L a Oi/iatat4-JL-TO> u o> id jfotL-i-jZJZi/iat l- u+j**- cw+j-rjj'D oj "oatoi TO-"— "4-TOTOTOL-J3' — > Cl-TO i — jzTOQ.aiatJZ3-r-o TO-r-at CC3i^n JUUC 2- J 1/131/1 > Oi o ■- L_ i*- Oi C i- to a> E ■— 213 214 relative to production in community metabolic studies of the standing water in these ponds and marshes. Periodic severe oxygen depletion was observed. Examination of plant community structure (Figure 1), aerial photo- graphy and water depths strongly sug- gest that the area north of the east- west levee, airport, and golf course was a freshwater habitat that was in- vaded by salt water species such as the red mangrove which have the abil- ity to live in "hard" freshwater. South of the artificial east- west levee and east of the airport runway lies a weak tidal mangrove community occupying a shallow basin approximately 119 hectares (ha) in area. It is dominated by black man- groves up to 6 m in height with a considerable admixture of smaller reds and whites. Large buttonwood snags along the dashed line between L and Q (Figure 1) attest to a formerly fresher regime, and a comparison of 1952, 1963 and 1974 aerial photogra- phy suggests a rapid continuing inva- sion of mangroves there, as well as to the north of the levee. Most of the basin remains shallowly inundated for much of the year, as a result of direct rainfall combined with rela- tively frequent though weak tidal penetration. evident in the 119-ha basin. This suggests that either (a) production of these materials is very low, or (b) tidal export is adequate to pre- vent accumulation of particulates. We suggest that the latter case pre- vails, and that there is a gradual net movement of particulates in a southeasterly direction through the basin or "impoundment" rim (shown as dashed line in Figure 1) toward the head of Unknown Bay. Figure 2 divides the 1,011- ha area south of the Belle Meade grade into four main zones based on the present duration of flooding. Zone 1 includes the living pinelands and adjacent sand barrens. These areas are infrequently flooded in their upper elevations and to depths of only about 13 cm at the lowest barren sites during the period June through September in years of normal rainfall. Zone 1 lies at a somewhat lower elevation than the lowest level of zone 1 but higher than zone 2. Zone 1 supports short spike rush, Eleocharis , which grows in water es- timated to average 28 cm in depth. This area is called "light rush" to conform with the terminology of Reark (I960; 1961) and Van Meter (1965). Flooding in zone 1 probably lasts from June through December .at the present time. Zones 1 and 1 cover about 267 ha. Tides probably penetrate the 119- ha basin on a seasonal basis by over- flowing laterally from the large ti- dal creek that flows north from the head of Unknown Bay. Tidal waters enter also on a more frequent basis via a series of shallow creeks and swales which penetrate the "lip" of the basin in the southeast. These also provide the main drainage from the basin. A build-up of flocculent mate- rial and leaf debris is not strongly Zone 2, variously covered by Eleocharis , red mangroves, rushes and salt joint grass, Paspalum distichum, lies at a still lower elevation. Measurement of water marks and peri- phyton growth on plant stems indicate an average maximum depth of flooding of about 38 cm, so these areas must lie about 10 cm lower than the zone 1 lands and about 25 cm lower than the seaward margins of the pineland barrens. Zone 2 is a region of "heavy rush" which probably remains flooded, at least with some water, during the 215 158 US 216 period June through February. The approximate area of zone 2 is 374 ha. Zone 3 is dominated by fresh- water red mangroves of the "spider" type (Craighead 1971) with consider- able acreage of open ponds along the northern edge of the zone. These ponds are often surrounded by tall Eleocharis or Paspalum. The clear water of these ponds, abundant peri- phyton and scant organic content of bottom muds suggests that, even here, dry down occurs often enough to per- mit oxidation of organics. Marginal depth of water over the pond rims (30 cm) where Eleocharis and Paspalum flourish is about the same as the average depth in zone 1 , but the depth of water in the open ponds probably averages 40 cm at nor- mal rainy season maximum or about 10 cm lower that the confining banks which support tall Eleocharis , Paspa- lum, and red mangroves. The hydro- period in this area probably averages 10 to 11 months. Within zone 3 but a little far- ther south of these clear water, shallow ponds, one first encounters permanent water ponds surrounded by dense stands of trees dominated by red mangroves. The water is heavily stained with humic acids and Chara sp. becomes the dominant submerged macro-plant. Ruppia maritima , or widgeon-grass, is often found in shallow margins of these ponds. Typi- cally, a berm surrounds these ponds and it appears that these ponds were once surrounded by buttonwood ridges on which cabbage palms grew as well. Peaty soil may exceed 60 cm in depth in these berms. The pond bottom sedi- ments are not peat but fine sand mixed with a high percentage of fine organic flocculent material which makes these muds extremely sticky. Where Chara flourishes there invari- ably is a blue mud deposit indicating natural anerobiosis and high produc- tion of H S and methane. Zone 3 oc- cupies 34f> ha . Seaward of the east-west running levee one enters the main mangrove forest association which can be best described as zone 4, polyhaline man- groves. Strictly speaking this zone encompasses the entire mangrove com- munity between Mcllvaine Bay and Unknown Bay. Primary interest, how- ever, is focused upon those portions lying east of the existing airport runway (Figure 1). The majority of this community consists of a 119- ha semi-impounded forest dominated by black mangroves of small to medium height lying behind the crest of a low levee (dashed line between L and Q of Figure 1) topped by large, dead buttonwoods . From that levee the land slopes gradually seaward to Un- known Bay and its associated creeks. The impoundment behind the low buttonwood levee had evidently expe- rienced greater fresh water influence prior to major drainage diversions further north. The increased saline influence has favored black and white mangroves at the expense of button- woods. In spite of the reduced fresh water input this impounded area re- mains inundated for up to 10 months of the year, and its lowest spots are probably always flooded to between 10 and 20 cm by a combination of resid- ual fresh and tidal waters. ACKNOWLEDGEMENTS I greatly appreciate the as- sistance and keen observations of Durbin C. Tabb and Gary L. Beardsley in preparing this report. 217 LITERATURE CITED Cavinder, T.; Hicks, D.; Howard, H.; Koenig, M. ; Murphy, P. A survey of physical, chemical and biolo- gical characteristics; Unit 30, Marco Island, Florida, August 1978 and March 1979. U.S. Envi- ronmental Protection Agency, Re- gion IV; 1979. Courtney, C. A limnological descrip- tion of Lake Marco Shores-- a man-made, brackish water lake. A thesis submitted in partial ful- fillment of the requirements for the Degree of Master of Science in Environmental and Urban Sys- tems at Florida International University; 1979. Craighead, F.C. The trees of South Florida. Coral Gables, FL: The University of Miami Press; 1971. Reark, J.B. Ecological investiga- tions in the Everglades. Uni- versity of Miami, Department of Biology, First Annual Report. 1960; 25 p. (mimeo) . Reark, J.B. Ecological investiga- tions in the Everglades. Uni- versity of Miami , Department of Biology, Second Annual Report. 1961; 19 p. (mimeo) Van Meter, N. Some quantitative and qualitative aspects of periphy- ton in the Everglades. Coral Gables, FL: University of Miami; 1965. Thesis. 218 MEROMIXIS IN A COASTAL ZONE EXCAVATION Charles M. Courtney Applied Environmental Services Marco Island, Florida INTRODUCTION Lake Marco Shores was created as a dredge and dragline excavation in 1972 when The Deltona Corporation de- veloped the Marco Shores Golf Course and Airport (Figure 1). Much inter- est has been expressed in this lake because of its use as a prototype of additional proposed excavations. Over the period 28 October 1976 to 21 June 1977, I conducted seven preliminary profiles of temperature, conductivity, salinity and dissolved oxygen in the lake. Observations indicated that Lake Marco Shores was developing a meromictic type of stability composed of three vertical strata: the mixolimnion, the chemo- cline, and the monimolimnion. MATERIALS AND METHODS Because each of the three layers was easily definable by in situ mea- surement, an intensive sampling pro- gram was employed from January to December 1978 to describe changes within these layers over an annual cycle. During that interval over 40 trips were made to each of two sta- tions on the lake (Figure 2) to moni- tor the vertical distribution of the following routine parameters: Secchi depth, temperature, conducti- vity, salinity, and dissolved oxygen. On 20 January 1977 during an unpre- cedented cold spell (air temperature reached 2.2°C) a profile of tempera- ture was made to a depth of 3.5 m in 0.3 m increments using a YSI Model 47 Scanning Telethermometer coupled to a YSI Model 80A Single Channel Laboratory Recorder. A series of twelve monthly chemical profiles were made. Nutrients were analyzed by standard methods (Strickland and Parsons 1972; USEPA 1974, 1975; Rand et al. 1976) . The bathymetry of the lake (Fig- ure 2) was accomplished during the period 25-26 October 1976 using a Raytheon Model DE-719B Survey Fatho- meter. Continuous climatological data were collected at two sites (Marco Island and Rookery Bay) which bracketed the lake at distances of approximately 4.8 km. Additional rainfall data were collected on a weekly basis at two locations in the watershed of Lake Marco Shores and at two locations on the lake shore (Figure 1), using Taylor wedge type rain collectors mounted on staffs which also served as ref- erences to monitor weekly surface water levels. On each trip to the lake actual wave heights were mea- sured against a fixed staff at the eastern end of the lake for compari- son with maximum theoretical values. Five clusters of 4 well points each were installed around the lake to de- termine if ground water exhibited the same vertical structure as the lake. 219 W (LI U o jC L ^ iLiOvV V D (/) 0) > cc 3 O 111 .-H s Ul 2 > c3 ro IT 8 T3 roooooooo 1 fit ii 0) co a-, wo w^jino fl o JIlDU -P LU nr O (0 or^ li-o o U en oo m \f\ B I O)]! UJ o < Q. UJ UJ (A o * IIW 2 K UJ < 3 — ' if/ * * Q (A c CD O // J7 W Z ^ -H (0 /tf <" 3 O fD CO LTl / / •- *" rH CO r~ ffAfl O 1- (9 O cr\ m s-j H // < 3 U. O o a >~^ // o: O UJ e c T3 C // ^ -J N 0 O * • — a, gj v-i u i J Jo> l\ x-x © 1— 1 co -J3 ■p eg IMA a; -p < £ £ (U UJ 0 X oe 0) M S +j-o £ nix; £ a) to O .a (0 B)Cifi!-HCH4J3 -p UJ ^ ^^. S-l D c a x s o a-H V4 CE \ X. w . (0 M0)t-i(nQ>OO f3 o X en \\ << _)Z < a* <^(B2S -K z OTO o — z UJ o o — t« < UJ < I w 0- _l UJ -1 \ 1 ^1 o 2* 2 of _J o < OIL J 03 u *-> s-i CO 3 u 3 'wo) llVdNIVy NV3H •QA9'N ("J) N0I1VA313 223 > H o U IH o W *■ wi rg (*") Hld30 IH303S 8 £ 8 s & (01 « I/6uj) v TUHdOHCHHO OJ (Ni — — (01 » I/6uj) NIlAHdOaVHd a = (LI a 03
  • > X! Oh O ^25- 0 O / \ •25 E < ■2 5 S Z / \ > UJ20 Uj2°- E K 111 / \ ■Ug U 1 z -20 w U. f \ IT UJ Ul t 15 / \ < O. 15- O O ■"5 in 0 .1.0 UJ \ 5io- -—- a-\ -15 O: 4 X O -1.0 1 ? .a Q \\ a 5 •s -05 UJ ^ I Q. -0 5 0900 1000 1100 1200 1300 1400 0900 1000 1100 1200 1300 TIME (hr.) ® TIME (hr.) ® 6/3/77 6/6/77 E 30- S— N FLOW ■ 3.0 "g 30- N — S FLOW -30 -~ 0 u O c 25- • 2.5 u £ 25- < /\ •25 i> E UJ O 20- ■2.0 1 UJ 20- / \ ' — * z O / \— /^ """"-^ -2.0 UJ UJ tr UJ 15 - u. Ul •15° i.a q. z UJ *v* \ K -1.5 < u. 5 10- 0 < Ul 5 - 1 T < Q ■ 0.5 u. u. 5 io« § j W 5- / ^-^ A O CO -10 Q -0.5 _ n 1300 1400 1500 1600 1700 1000 1100 1200 1300 1400 1500 TIME (hr.) © TIME (hr.) ® -H4: 6/21/77 - 3.0 0 ^Hnmul^ N^S FLOW 0> jc < 0 - 2.5 E 1= u 4C rr^° "■ 0 UJ ^^* -C 4) O z X - A & - 20 0 < 4/5/78 1/) > UJ3! K 111 Li- it 30 O: < - 1.5 I O 1/) UJ 0 is- z UJ N— S FLOW _E ■ 15 *"* UJ 0 •3 4-> r-l CO ca 3 5- 4-1 u 00 >1 x: ■ . 5 .5 3 ■2 c ^ 1 TOTAL MONTHLY WATER DISCHARGE (M5/M0N) % N— S FLOW M -* ♦ rt n — > o 1 ^^^^^^ z ^^^Z-J- ►- 8 ^ ~~ ■ ^ ^ «■"■ """ a. III -1 K T r~"" u to ,< < o W|j £ 5 ^\ 3 < oil zH K a ^"V ^*>* ™ J -- 3 ! t \ --' - ti •tC **^^ z - -> < z y s Jr* ' I 4 ^^\v O z ^ » 8 0 i -^— - ^^^ 3 < -J ^==~~~^7^:~-~^~~-~^ 3 -» Z 1 1 1 1 1 ~—» — 1 ' \ 3 5 s "go «n o « o *> to rt N N — — RAINFALL (CM) 237 DATE APRIL 1978 (DRY SEASON) 0.91 TIDE HEIGHT (m) 0-38 0 NGVD H -0.15 NORTH GAGE SOUTH GAGE 1 1 i 3 5 6 DATE SEPTEMBER I978 (WET SEASON) FIGURE WET SEASON VS DRY SEASON MEASURED WATER LEVELS AT NORTH AND SOUTH ENDS OF CULVERTS 238 not always agree with field measure- ments (for example Figures 3B and C) , it is apparent that averages of observed and computed discharges taken over several points are in good agreement. A statistical analysis revealed that when averaging over a month the discharges computed from the 6-min tide records yields a maximum probable error of 0.075 m /sec at the 90 percent confidence level (Daddio and van de Kreeke 1979). RESULTS Figure 4 is a plot of the monthly rainfall recorded at the Rookery Bay Marine Station and the net monthly water discharge through the culverts computed using Eq. 4. The net water discharge is exclusively toward the south for the entire recording period. The discharge hydrograph shows a definite seasonal trend with the largest discharges occurring during the wet season (here defined as June through September) . The maximum monthly discharge for one year beginning June 1977 is 3.51 x 10 m /month in July 1977. The dry season discharges are still sut>7 stantial and on the order of 10, m„/month with a minimum of 0.27 x 10 m / month during the month of Nov- ember 1977. For comparison the subsurface ^run-off is estimated at only 10 m /month based on figures presented by Amy (1980). It is noteworthy that although water flowing through the culverts experiences tidal reversals for most of the year relatively few reversals occur through the wet season months. This is exemplified by measured water levels at the north and southside of the culverts during April (dry season) , and September (wet season) ; see Figure 5. During September the water levels on the northside are practically always higher than the levels on the southside leading to unidirectional flow. During April the head difference changes sign. Mean water levels during September are about 0.20 m higher than during April . The total rainfall for the 1- year period beginning 7June 1977 is 144 cm or 3.11 x 10 m for the drainage basin of which 1.66 x 10 m was discharged through the cul- verts. This yields a run-off ra- tio of 0.53 for the drainage ba- sin. Assuming no net water stor- age over a period of a year, the remaining 47 percent of rainfall is lost largely by evapotranspi- ration. This percentage is consid- erably lower than the 76.2 per- cent evapotranspiration reported for the Big Cypress Swamp (Carter et al. 1973) . This may be a result of accelerated runoff associated with channelization in this study area. Also, there exists a possibility that the freshwater lens on the golf course (Amy 1980) forces ground water derived from areas north of the drainage basin to surface and be- come part of the surface runoff. CONCLUSIONS Water export is determined with a semi-empirical relationship between discharge and water eleva- tion differences across culverts which convey surface run-off out of the study area. Monthly water export ranges from 0.27 x 10 m / November 1977 to 3.51 x for July 1977. The total flow fox a one-year period is 1.66 x 10 m representing 53 percent of the rainfall. mouth for 10 m /month 239 REFERENCES Amy, V.P. The ground-water flow system in the vicinity of Marco Island, Fla. Cross, R. ; Wil- liams, D. , eds., Proceedings of the National Symposium on Fresh- water Inflow to Estuaries. San Antonio, Texas, September 9-11, 1980. Washington, DC: U.S. Fish and Wildlife Service, Office of Biological Services; 1981. FWS/ OBS-81/04. Carter, M. et al. Ecosystem analysis of the Big Cypress Swamp and estuaries. U. S. Environmental Protection Agency, 1973. Region IV; Daddio, E.; van de Kreeke, J. Flux of dissolved organic carbon from a wetland area near Marco Island, Fla. Miami, FL: University of Miami; 1979. Rosenstiel School of Marine and Atmospheric Sci- ence Tech. Rep. TR 79-2. Tabb, D.; Heald, E.; Beardsley, G. Natural resource assessment of Marco Island Mainland properties tract. Report to Deltona Corp., Miami, FL; 1977. Unpubl. ms . WATER BUDGET AND PROJECTED WATER QUALITY IN PROPOSED MAN-MADE LAKES NEAR ESTUARIES IN THE MARCO ISLAND AREA, FLORIDA Wayne C. Huber and Patrick L. Brezonik Department of Environmental Engineering Sciences University of Florida, Gainesville, Florida INTRODUCTION The proposed Marco Island de- velopment plan calls for the excava- tion of a large group of intercon- nected lakes in two areas known as Units 24 and 30 near Marco Island, Florida . The area has been described in detail elsewhere in this series. The land uses and lake areas are tabulated in Table 1 for Units 24 and 30. The latter is considerably larger both in total area and lake area. Existing Lake Marco Shores (see paper by Courtney) also will be incorporated into the lakes of Unit 30. The quality of the proposed lakes is of considerable importance, both to the riparian owners and to the nearby estuarine areas that will receive surface discharges. Although the areas will be surrounded by berms sufficient to contain the 100-year storm volume, some net runoff will leave via spreader ditches and enter the mangrove and marsh areas. Hence, an a priori assessment of lake water quality was desired to evaluate the potential for problems within and downstream of the lakes. This paper describes the techniques used for the assessment. Although the potential exists for a variety of pollutants to enter the lakes, only a few are criti- cal to the lake evaluation. In par- ticular, the nutrients, total nitro- gen (T-N) and total phosphorus (T-P) are important to the long term po- tential for eutrophication and are examined in detail. Such common parameters as dissolved oxygen will not be a problem on the basis of data from existing Lake Marco Shores and experience with similar lakes else- where. Moreover, the scope of the parent investigation did not require a comprehensive evaluation of all water quality parameters. Hence, T-N and T-P are emphasized in this paper. A complication is the fact that the deep lakes will be stratified due to the influx of hypersaline ground water below a depth of roughly 6.5 ft (2.0 m) . Based on samples from existing Lake Marco Shores, water in the lower layer (monimolimnion) will likely be of poor quality, with high concentrations of nutrients. The fresh upper layer (mixolimnion) , on the other hand, should be of much better quality; the point of this investigation is to determine how much better. The lakes will be meromictic, that is, permanently 241 Table 1. Land use categories, Unit 24 Unit 30 (ac) (%) (ac) (%) Residential (Including schools, churches, parks, golf courses) Commercial Roads & Right of Way Multi-Family Residential TOTAL LAND AREA 234.7 44 1147.77 40 19.2 4 72.6 14 121.9 23 448.4 85 115.26 4 491.74 17 423.57 15 2178.34 76 Lakes Major Lake-Deep Area Major Lake-Shallow Area TOTAL LAKE AREA TOTAL AREA 60.20 361.64 19.76 342.55 79.96 15 704.19 24 528.36 100 2883.53 100 NOTE: 1 ac x 0.405 = ha 242 Table 2. Lake water budget evaluation. Unit 24 (in/yr) Unit 30 (in/yr) Inflow Precipitation Surface Runoff Interflow Groundwater 50.0 50.0 30.8 17.2 39.2 21.9 41.2 14.0 Inflows 161.2 103.1 Outflows Groundwater Evaporation Surface Outflow 41.2 14.0 44.4 44.4 75.6 44.7 Outflows 161.2 013.1 (Note : Inches x 25.4 = mm) 243 stratified. Density differences are so great across the chemocline that the possibility of overturn is nil. Hence, the lower layer will influence the upper only by vertical diffusion. and 0.65 years for Units 24 and 30 respectively. These values influence lake water quality. LAKE NUTRIENT LOADINGS LAKE WATER BUDGET The lakes receive water from surface runoff from the various land uses; from interflow, (i.e., water that infiltrates to the shallow water table, forms a ground water mound, and thence moves laterally to the nearby lakes) from regional ground water flow in the shallow fresh water layer, and from direct rainfall. Water is lost by surface runoff, ground water outflows and evapora- tion. If the change in storage is zero on an average annual basis, then inflows equal outflows, and the water budget equation may be evaluated for each term. Annual precipitation in the area is about 50 inches (1,270 mm). Surface runoff and interflow were evaluated utilizing a land surface evapotranspiration rate for the region of 75 percent of annual rain- fall (Figure 1). Groundwater move- ment was determined by analysis of regional potentiometric contours (see paper by Amy in this proceedings). Lake evaporation was taken as 70 per- cent of pan, and surface outflows were deduced by subtraction, knowing all other terms. The derived water budget is shown in Table 2 in which units are inches over the lake surface area. Assuming the depth of the fresh- water layer in the lakes will be 6.5 ft (2 m) (Figure 2) residence times for these layers may be computed by dividing the volume above this depth by the sum of inflows (or outflows) in Table 2 expressed as a volumetric flow rate, yielding values of 0.42 The primary task is to develop loadings for TN and TP that coincide with the various pathways of the water budget inflows to the lake, plus possible diffusion from the lower layer. The latter was cal- culated on the basis of gradients measured across the chemocline in existing Lake Marco Shores. Concen- trations in ground water and rainfall were measured. Loadings for urban stormwater were needed to evaluate this contribution to surface runoff and interflow. Fortunately, Broward and Dade Counties (near Fort Lauderdale and Miami) in southeast Florida were the sites of four intensive urban runoff monitoring programs by the U.S. Geological Survey (USGS) in the mid 1970' s (Mattraw and Sherwood 1977; Mattraw and Miller 1978; Hardee et al. 1979; Miller et al. 1979). These data were acquired as part of the EPA Urban Rainfall-Runoff-Quality Data Base (Huber et al. 1979) and analyzed statistically to develop flow weighted average concentrations which were then used to develop surface runoff and interflow loadings to the lakes. The USGS data are appropriate for use in the study area because of similar meteorologic, hydrologic, and demographic charac- teristics of the locations. The USGS data also have the unusual advantage of a large number of sam- ples, from 15 to 41 storms at the four sites of differing land uses. Incorporating the various fluxes, the nutrient loadings shown in Table 3 are developed. Of interest is the influence of the lower layer on both T-N and T-P and the relative 244 insignificance of urban run off on T-N. IMPLICATIONS FOR LAKE WATER QUALITY An assessment of predicted im- pacts on the lakes of the T-N and T-P loads may be performed using critical loading rate estimates developed by Vollenweider (1975) and Dillion and Rigler (1975), and specifically for Florida lakes, by Brezonik and Shan- non (1971) and Kratzer (1979). Two sets of critical rates are given: those below which the lakes should remain oligotrophic ; and those above which the lake should tend to eutro- phy or suffer degraded water quality. These are compared in Table 4 with the loadings of Table 3. On the basis of N:P ratios for the lakes, phosphorus is probably the most important relative to the pre- diction of trophic conditions. Phos- phorus limitation is in fact typical of most lakes , with nitrogen limita- tion occurring only in unusual geo- logical circumstances or for lakes receiving large loadings of sewage effluent (which typically has very low N:P ratios). Units 24 and 30 will be on central sewers and the proposed lakes will receive no sewage effluent. The phosphorus loading rates for the lakes are at or below the exces- sive levels given by both Vollen- weider (1975) and Brezonik and Shan- non (1971). The lakes of Unit 24 receive higher loadings than those of Unit 30 in part because they have more deepwater with a large flux due to vertical diffusion. On the basis of the phosphorus loading rates, lakes in both units are expected to be mesotrophic with fair to good water quality. The T-P concentrations in the lakes may be predicted using mass balance approaches in which the steady state concentration is a function of loading rate, detention time and mean depth (Dillion and Rigler 1975; Kratzer 1979). The predicted average T-P concentrations are 0.020 to 0.026 mg/1 for Unit 24 and 0.014 to 0.019 mg/1 for Unit 30, respectively, where the range results from using several different pre- dictive relationships . These ranges are consistent with observed T-P concentrations in existing Lake Marco Shores. On the basis of the nutrient loadings and T-P concentrations other parameters can be predicted by vari- ous regression relationships. On the whole, predicted water quality is good with Secchi disk transparencies on the order of 1.2 to 1.5 m and T-N of about 1 . 3 mg/1 . Chlorophyll a levels in the lakes have been predicted using cor- relations of average T-P vs. chloro- phyll a reported in the literature (Dillion and Rigler 1974 and Kratzer 1979), and from reported predictive relationships between phosphorous loading rates and chlorophyll a levels (Kratzer 1979). Predicted chlorophyll a concentrations range from about 6 to 13 nig/m in Unit 24 and from 3 to 13 mg/m in Unit 30. These values are in the mesotrophic to slightly eutrophic range. Chloro- phyll a is a commonly used trophic indicator, and it serves as a measure of algal biomass in lakes. In summary, the predicted water quality parameters indicate that water quality in the proposed lakes will be satisfactory and that nutri- ent-overenrichment will not be a problem. 245 Table 3. Nutrietn loads tolakes in units 24 and 30. Unit 24 Unit 30 1096 (30%) a 5164 (32%) 408 (11%) 3590 (22%) 1879 (51%) 5618 (35%) 289 (8%) 1746 (11%) T-N Loads Surface + Interflow (lb/yr) Rainfall (lb/yr) Groundwater (lb/yr) From Lower Layer (lb/yr) Total Load (lb/yr) 3672 16118 Normalized Loading (lb/ac/yr) 2 (g/m /yr) T-P Loads Surface + Interflow (lb/yr) Rainfall (lb/yr) Groundwater (lb/yr) From Lower Layer (lb/yr) Total Load (lb/yr) 225 1154 Normalized Loading (lb/ac/yr) 2.81 1.64 (g/m2/yr) 0.32 0.19 Percent of total load. Loading = total load/watersurface area. 45.9 22.9 5.2 2.6 114 514 (51%) (45%) 28 246 (12%) (21%) 36 108 (16%) (9%) 47 286 (21%) (25%) 246 CU CN ON 00 i— I ■-I r~ m r~ CO ^O CM •• •H CO Q 60 3 2 /■N o <: o CNI 00 vtrl v£> . l-i o CM a a. 3 o o o o o o o o o o O ut-l UM H o s^ cn M Vj cu cfl z 4-J i-i 3 O 00 c ^3 cfl cu l-i u pi •iH ■r-l 00 o 1—1 CO cfl o t-l "O Z • 1 1 1 1 • 1 1 1—1 Pn O o CM 1 1 1 1 CO CN 1 ' l-l cfl -3 O ^ CN ON •i-l W o ~^ CO 1—1 4J 3 z CN Ph| • . •H • . M B o o l-i CO i—l ON Q II II O cfl CM VO E W en CU Zl • • l-l a a, H cu l-l UO CM CU • pi Pi u X < 4-i cn M c cO cu u . Q o J ■3 O u u 3 •H CO CO en J3 >. >. 4-j en cr cr O O 4J ^N^ ^^ (X co l-i N O en m cn „ co 4J 3 cfl E E Q •■-I U IN IN cr Q. cr Q- 4-) •3 r-- on 2 r-l CJ Pi pi •H cu en ON , i-l i—l CO 3 CO ■ PL.I • . cn > cn cn CO O o cu cr cr ^ Q 4J •r-l l-l l-l < CO CJ ^ •— s /-N C O cfl JD r^ CO lO i—l rJ en )-i >% 5n >, 1-1 u l-i U 4J . 60 4-) 4J ~-~ N*- "-- >% >, ?N l-l 4-J 1—1 O rW H C -H 0) co CNI CN ■*-* o CU CO U 2 ■H C g g r-l g -h g i—l CN i—l CN i—l CN U-t e cj O II II W •3 ^ 3 --~ cfl \ CO \ co 6 co e co E 3 •H M CO i— l 60 cu eo cu to a; --~- CU ^ CU ~- w i—i -i -— U^' u to u to l-i to CU o Zl • . >. C H en ►J > < < < ^ < ^ < ^ w > CN i—i JZ o 3 cu CO CL-r4 • Z CO s~\ Pi 4-1 • • CO e e ►J pi en 60 cn 3 r-~ r^ < r-^ c l-i cr . u oc ON •H O cu r-l !-H l-l c /— \ i—i Cx-s -3 4J H •H C m ^ O UO CO CJ - II II M T3 o r>. u i—l r-- O Cfl 4J Pi CO e CJN C -* X. rj S^J P-, E .—I Cu N r-~. 1-1 i—i r-~ J-i •U 4J u cu 4J 4J « s 0) ON 1—1 r-l on CO^-v •-N •H ■i-l o x; •r-l -r-l < o l-i .-i o •r-l r-l y> i-i CN . C c Z 4-J C C H U < 03 n^ > Q^ ^:^ ^■s 03 z Z CO Z Z 247 RAINFALL 100% EVAPOTRANSPIRATION 75% SURFACE RUNOFF 1 1% LAKE LEVEL ♦6.0 NGVD ♦2.0 NGVD 0.0 NGVD -4.5 NGVD FIGURE 1 THE LAND SURFACE WATER BUDGET 248 SOUTH & SOUTHWEST NORTH & NORTH EAST ESTUARY EXISTING GOLF COURSE ■EXISTING LAKE GROUND SURFACE POTENTIOMETRIC SURFACE RECHARGE INTERFACE (CHEMOCLINE)^ IN LAKE HYPERSALINF GROUND WATER INTERFACE - ACTUALLY 'A TRANSITION NOT SHARP AS SHOWN. A. EXISTING ESTUARY NATURAL AREA SPREADER DITCH DEVELOPMENT AREA SHALLOW LAKE DEEP LAKE INTERFACE (CHEMOCLINE)^ IN LAKE FRESH GROUND WATER HYPERSALINE GR B. PROPOSED FIGURE 2. REGIONAL GROUND WATER PATTERN. 249 DISCHARGES TO ESTUARIES Using the predicted surface outflow rates and concentrations, discharges of T-P and T-N to the nearby estuaries may be computed as 65 kg/yr and 5,060 kg/yr, re- spectively, from the two units. These values are somewhat less than present discharges from the area due mainly to a reduction in surface outflows under the planned develop- ment. On the basis of nutrient loads, the urban development is ex- pected to have little impact on the estuaries . SUMMARY Methods exist for prediction of lake and effluent water quality for the projected urban developments in southwest Florida. Analysis of nu- trient budgets for the proposed lakes indicates mesotrophic condi- tions (fair to good water quality) with no deleterious effect on estu- arine marshes. ACKNOWLEDGEMENTS This study was performed for the Deltona Corporation, Miami, Florida. LITERATURE CITED Brezonik, P.L.; Shannon, E.E. Tro- pic state of lakes in North Central Florida. Gainesville, FL: University of Florida; 1971. Water Resources Research Center Publ. 13. Dillion, P.J.; Rigler, F.H. The phosphorus chlorophyll relation- ship in lakes. Limnol. Oceanogr. 19:767-773; 1974. Dillion, P.J.; Rigler, F.H. A simple method for predicting the capacity of a lake for develop- ment based on lake trophic status. J. Fish. Res. Board. Can. 32: 1519-1531; 19 75. Hardee, J.; Miller, R.A.; Mattraw, J.C. Jr. Stormwater runoff data for a highway area, Broward County, Florida. USGS Open File Report 78-612. Tallahassee, Flo- rida, 1978. Hardee, J.; Miller, R.A. ; Mattraw, J.C. Jr. Stormwater runoff data for a multifamily resi- dential area, Dade County, Florida 1979. Huber, W.C.; Heaney, J. P.; Smolenyak, K.J. ; Aggidis, D.A. Urban rain- fall-runoff-quality data base, update with statistical ana- lysis .Cincinnati , OH: U.S. En- vironmental Protection Agency. EPA Report EPA-600/8-79-004; 1979. Kratzer, C.R. Application of input- output models to Florida lakes. Gainesville, FL: Dept. of En- vironmental Engineering Sciences University of Florida; 1979. 169 p. Thesis. Mattraw, H.C. Jr.; Hardee J., Miller, R.A. Rainfall, runoff, water quality and load data for a residential area, Broward Coun- ty, Florida. Tallahassee, FL: U.S. Geological Survey; 1978. USGS Open File Report 78-324. Mattraw, H.C. Jr.; Sherwood, C.B. Quality of stormwater runoff from a residential area, Broward County, Florida. USGS Journal of Research 5:823-834; 1977. Miller, R.A.; Mattraw, H.C. Jr.; Har- dee, J. Stormwater runoff data for a commercial area, Broward 250 County, Florida .Tallahassee, FL: U.S. Geological Survey; 1979 USGS Open File Report 79-982. Vollenweider , R.A. Input-output mo- dels, with special reference to the phosphorus loading concepts in limnology. Schweiz. Z. Hy- drol. 37:53-84; 1975. 251 THE GROUND WATER FLOW SYSTEM IN THE VICINITY OF MARCO ISLAND, FLORIDA Vincent P. Amy Geraghty & Miller, Inc. West Palm Beach, Florida INTRODUCTION The Deltona Corporation's planned development of a coastal area near Marco Island includes the creation of a series of intercon- nected lakes ranging in depth from a few feet to as much as thirty feet. Construction of these lakes will penetrate the water table aquifer in an area that is a mix of coastal wet- lands and uplands. Because the lakes are to be created as part of a com- munity development, one of the fact- ors to be considered is the impact on water quality. The previous section of this re- port revealed that both fresh and hypersaline water existed in Lake Marco Shores. Because of the ge- ometry of the lake and the density difference between the two fluids, no mixing has occurred; a distinct boundary exists between the two. Hypersaline ground water also was found in shallow wells drilled in the vicinity of the lake. Much has been written regarding the effect of runoff on the quality of lake water; little has been written on the in- fluence of ground water quality and the contribution of the ground water flow system. Accordingly, this study was conducted by Geraghty and Miller to investigate the influence of ground water on the proposed lake system. The principal goals were to estimate groundwater input to the the property and to investigate fresh-salty ground water relation- ships in the vicinity of Lake Marco Shores . METHODS The study was based on evalua- tion of data collected from a variety of sources--an existing network of multi-zone monitor wells on the pro- perty, new multi-zone wells, explora- tory and observation wells installed by the South Florida Water Management District (SFWMD) , and information from published reports. In addition to an existing network of five multi- zone monitor wells on the property, multi-zone monitor wells were in- stalled at five other locations on the property to provide more complete coverage. Two wells, 10 and 30 feet deep (3.05 and 9.14 meters) were in- stalled at each site. Each well was sampled during drilling and geologic logs were prepared. After completion and development, water samples were collected from each well and sent to a certified laboratory where analyses for selected constituents were performed. The elevation of each well was determined so that water level measurements could be refer- enced to NGVD (National Geodetic Vertical Datum) and contour maps and cross-sections depicting the groundwater flow system could be prepared . 252 The observation well network was completed in late February 1980 dur- ing the dry season. Since then, Applied Environmental Services (AES) personnel have been measuring water levels periodically. These measure- ments have been used in preparing water table contour maps. In addition to site-specific data, similar information from areas surrounding the property also has been used. Data on water levels, quality, and geology from a network of exploratory and observation wells installed by the SFWMD were used to depict regional conditions. The locations of all wells are given on Figure 1. Information also was obtained from a variety of published reports dealing with the hydrogeology of the general area. Clay and silt layers are not present. The thickness of the sand ranges from five to six feet north of the planned development to as much as 25 feet (7.62 meters) near the west end of Lake Marco Shores. In general, the sand is thicker along the southern part of the area near the lake and thinner to the north. The Fort Thompson-Caloosahatchee Marl Formations (undifferentiated) underlie the sand throughout the study area. Typically, these forma- tions consist of ±20 feet (6.1 meters) of a hard, sandy, shelly limestone. Marl is present in places. Near the bottom of this zone, cavities are frequently en- countered. Most of the observation wells installed as part of the Geraghty & Miller field program pene- trated cavities in the upper 20 feet (6.1 meters) or so of the limestone. RESULTS SUBSURFACE CONDITIONS The zone of interest in the study area consists of the upper 30 to 60 feet (9.14 to 18.3 meters) of sedimentary rocks formed by uncon- solidated sand and limestone. A typical cross-section is illustrated in Figure 2. The section is drawn approximately parallel with the di- rection of groundwater flow. The entire area is overlain by a veneer of fine- to medium-grained clean, quartzitic sand (Pamlico Sand) with varying amounts of organic material. The upper one foot or so consists of silty, peaty material throughout much of the area. The predominant color of the shallower sand beds is tan to brown, owing to the presence of and staining by organic matter. Deeper portions of the sand range in color from tan to gray. The Tamiami Formation underlies the Fort Thompson-Caloosahatchee Formations. The upper portion of the Tamiami Formation consists of the Ochopee Limestone member which is about 130 feet (39.6 meters) thick. This unit consists of abundant shell fragments and cavities, particularly above depths of about 80 feet (24.4 meters) . HYDROLOGIC CHARACTERISTICS The Pamlico Sand and the under- lying limestone formations form a single hydrologic unit, especially in the upper 80 feet (24.4 meters) or so. No clay or silt confining beds are present in the Pamlico Sand, and there appear to be no con- fining units in the limestone. Thus, the sand will transmit water to the limestone and vice versa, so that both the sand and limestone respond hydrologically as a single unit form- ing a water table aquifer in the area, 253 FIGURE I. LOCATION OF OBSERVATION WELLS AND SECTION A -A. 254 o o I o ro O I O in I O 10 I 291 85|D1- c c O O .O o> 01 £ 0) a c a a. a. >> < X E > o E o 3 T3 C o 11) e o XI E 5 o a> <7> „ ^ >. -i —> N, c o en E o s (i) "5 o > CO CD JZ >> S- re 3 +-> on UJ o •I — U CD l\l CD +J •r- 3 c o * — * ■f — UJ 4-> Q_ u n (_> "O re •i — s- S- CO jz o +-> (O u 1 Q_ ■ 00 C_) O- 3 . Q. • E Q CD oo LU CD O LU > □_ > CLCO re 1— O re O cC ■1 — S_ LU 4- end 4- +-> Qi o 3 LxJ o C O 21 CO CD ^ £Z 1 1 C7> 3 or. 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Although this is not a complete look at the effects of the agricultural canals, it aids in the interpretation of St. Lucie Canal discharge effects. For instance, in interpreting the move- ment of sheephead, the influences of discharges from the St. Lucie Canal or C-23 alone do not indicate an exodus from the inner estuary to cause the increase in the catch rate in the inlet section. However, analysis of discharges from C-23A in- dicate that the first response is a decrease in catch rate in the North Fork followed by an increase in the inlet section. The analysis of C-23A flow has apparently captured subtle- ties in the change in rates that the other analyses have not. PAST AND PRESENT SPORT FISHING PRESSURE The total number of boaters in the North Fork and fishermen in the South Fork, bridge and inlet sections, was estimated to be 70,500 angler days spent in the late 1950' s (Table 4). Estimated angler days for this 1978-79 study (including for comparison only the boaters from the North Fork) was 66,303. Based on a 25-year projection included in the Fish and Wildlife Service 1959 report, the current angler utilization is less than the actual 1956-57 survey and only 42 percent of the projected amount . Over the years, species prefer- ences in the North Fork have changed and diversified. However, the per- centage of fishermen who are after certain species has remained about the same and snook still leads as the most preferred species. In terms of species that make up the harvest, snook has dropped from over 26 per- cent of the harvest to just over 2 percent in this survey. Croaker has also dropped significantly from 14.1 percent to only 3 percent of the harvest, whereas gray snapper has remained about the same. Three species that have greatly increased as a percentage of the harvest are bream or sunfishes which have moved from 1.3 percent to 19.3 percent, mullet which has increased from 0.5 percent to 18.9 percent, and the com- bined catch of weakfish and spotted seatrout which has increased from 0.5 percent of the harvest to 8.2 percent in this study. North Fork catch-per-unit of effort was calculated for the months July through April. The puffer, mul- let, and bream catches have signifi- cantly increased the catch rates for the summer months. In the 1956-57 survey, the most successful month was December. February, with a substan- tial contribution by bream, was the most successful month of this 1978- 79 survey. CONCLUSIONS The catch rates of nine impor- tant fish species were found to be significantly influenced by the mod- erate freshwater discharges from the St. Lucie Canal, Stuart, Florida, 277 >, ( — 1 i—i S- ro —^ +-> QJ a>^ ^ ^^ N CU 3 -^ CU ro c 3 C sz -^ j^: -^r. 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The dis- charges from the St. Lucie Canal over the survey period amounted to 440,000 acre-feet as compared to the previous 21-year average of 561,000 acre-feet. In addition, 91,000 acre-feet from C-23 and 88,000 acre-feet from C-23A also flowed into the estuary during the survey period. We propose three theories for the significant changes in catch rates we found in response to the moderate discharges: (1) movement within the estuary, possibly due to the enhanced food supply flushed through with the freshwater; (2) movement to adjacent areas within the estuary that are initially less influenced by the effects of the dis- charges; and (3) movement to the far- thest zone from the discharge sources . Both snook and mullet moved within the estuary in patterns that would indicate movement in response to food supply. However, snook being carnivorous, exhibited a more in- stantaneous reaction. Small fishes, including juveniles and forage fishes are often flushed through with the discharges. As a result, it is a well-known fact that snook move to these structures during discharge periods and are more easily caught. Mullet, on the other hand, consume primarily detritus and algae. Their feeding response, evident after pro- longed discharges, may be a side- effect of the increased detrital ma- terial made available. Mullet also demonstrated tempor- ary movement into the South Fork in response to North Fork discharges as did gray snapper. Previous studies indicate that a stratified layer of freshwater moves out of the South Fork, into the main estuary, and out the inlet following St. Lucie Canal discharges (Haunert and Startzman 1980). If indeed waterflow from one or the other fork results in minimum mixing with the adjacent fork, then the sheltering effect of the adjacent fork, not only from salinity changes but associated turbulence, is an important consideration in fish move- ment . It is evident that there may be a threshold discharge amount beyond which sheltering is no longer effec- tive. For example, gray snapper catch rates increased instantaneously down the South Fork as a result of North Fork discharges. However, as the duration of North Fork discharges lengthened, catch rates for snapper increased in the inlet section. Indications are that the first re- sponse of gray snapper may be to move to the South Fork as a result of North Fork discharges, but soon afterwards, as effects are felt in the South Fork as well, movement is toward the inlet section. Sheepshead, black drum, Irish pompano or mojarra, weakfish, gaff- topsail catfish, croaker and event- ually gray snapper all showed a tendency for increased catch rates in the inlet section, the farthest zone from the discharge sources. This movement lagged 1-6 weeks behind the discharge. Although several of these species are considered to be salinity limited, they were all affected simi- larly by the discharges. An analysis was done to see how the four inflow sources, rain, St. Lucie discharges, C-23 and C-23A discharges, affect the time fisher- men spend on the estuary. Short-term effects of the discharge sources on fishing pressure indicate that neither weekly cumulative rainfall 280 nor St. Lucie Canal discharges sig- nificantly affect fishing pressure throughout the estuary. On the other hand, increases in North Fork dis- charges (C-23A) were found to be correlated with increased South Fork usage. However, fishing pressure in both the North Fork and inlet section were negatively affected by C-23 and C-23A freshwater releases. Comparison of this study with studies done on the North Fork in 1959 and fishermen counts done on the estuary, indicate that less angler days are spent on the St. Lucie now than in the late 1950's. The cause of this loss in angler usage over the past 22 years may be the drop in harvest percentages of the most de- sirable species, notably snook, croaker, and tarpon. In terms of fishermen's expenditures, the cost of this loss amounts to approximately one million dollars per year. In conclusion, freshwater dis- charges by the St. Lucie Canal were found to have significant short-term effects on the catch rates of nine important estuarine species. Essen- tially what this means to local fishermen is that during discharges species habits are less predictable, and the augmented freshwater releases are causing fish movements. Long-term analyses show an actual drop in angler usage of the estuary in the face of great increases in human populations. LITERATURE CITED American Fisheries Society. Special Publication No. 6, 3rd Edition, 1970. Gunter, J.; Hall, G. Biological investigations of the St. Lucie Estuary (Fla.) in connection with Lake Okeechobee discharges through the St. Lucie Canal, 1963. Gulf Coast Research Lab- oratory 1(5): 189-307. Haunert, Daniel E.; Startzman, J. Some seasonal fisheries trends and effects of a 1,000 cfs freshwater discharge on the fishes and macroinvertebrates in the St. Lucie Estuary, Flor- ida, 1980. South Florida Water Management District, Technical Publication 803; 1980. U.S. Dept. of the Interior, Fish and Wildlife Service. An interim report on the fish and wildlife resources in relation to the Corps of Engineers plan of development for the St. Lucie Canals, Florida; 1959. U.S. Dept. of the Interior, Fish and Wildlife Service. A report on the effects of the St. Lucie Canal discharges on the fish and wildlife resources of the St. Lucie River system (A unit of Lake Okeechobee regulation) , 1960. Preliminary draft. A list of common and scientific names of fishes from the United States and Canada. Washington, D.C.: U.S. Dept. of the Interior, Fish and Wildlife Service. 1970 National Survey of Fishing and Hunting. Resource Publication No. 95. 281 EFFECTS OF FRESHWATER RUNOFF ON FISHES OCCUPYING THE FRESHWATER AND ESTUARINE COASTAL WATERSHEDS OF NORTH CAROLINA Frank J. Schwartz Institute of Marine Sciences University of North Carolina Morehead City, North Carolina ABSTRACT INTRODUCTION Presently 37 freshwater and 77 marine fishes, within 13 freshwater and 38 marine families, respectively, are known to inhabit the oligohaline or euryhaline "freshwater" estuaries of coastal North Carolina for pro- longed periods. Most species are typical primary, secondary, diadro- mous, complementary or sporadic fishes, as defined by Myers (1938; 1949a, b; 1951). Eighteen of the freshwater and 37 of the marine fishes noted are new additions to the lists compiled by Schwartz (1964) and Gunter (1942, 1956) of known fishes which occur in low salinity fresh waters. The extent of the euryhaline zone created by seasonal or sudden runoff conditions, is described for each of the major coastal watersheds of North Carolina. Maximum or mini- mum salinity occurrence levels are noted for each species frequenting the area. Comments similar to Gunter et al. (1974) are presented on length of survival in low saline water situations and/or responses to other environmental variables, in relation to fish size. habitats Douglas Fishes are usually categorized as primary, secondary, peripheral freshwater or marine, yet we know that there are anadromous, cata- dromous, diadromous, amphidromous , potamodromous , oceanodromous , vicar- ious, complementary or sporadic (Myers 1938; 1949a, b; 1951) fishes that pass into or out of fresh or marine regimes (Hoar and Randall 1979). Faunal fish surveys, however, are usually stilted to sampling either in fresh or marine (i.e., Carr and Goin 1955; 1974; Livingston et al. 1976, 1977). Occasionally, there have been efforts to study the "salting out" effects where fresh waters mix with marine waters (i.e., Chesapeake Research Consortium 1976; Lauff 1967; Wiley 1978). More importantly almost no prolonged study has been aimed at that unstable area where fresh waters meet estuarine waters, the area that was estuarine and which suddenly is transformed into a freshwater habitat by increased freshwater run- off or to what happens to the fish faunas of either regimes when 282 subjected to sporadic or rapid freshwater intrusions. DEFINITIONS AND TERMINOLOGIES While some would prefer to call that area located between fresh and saline waters, where two waters di- lute each other, an estuary (Hedgpeth 1951; McHugh 1966; Lauf 1967; Prit- chard 1967a), others designate it as brackish waters (Dahl 1956; Kinne 1964; Caspers 1967). To others the battle rages on in the search for an adequate terminology that defines the freshwater-saline interzone (McHugh 1967; Abbott and Dawson 1975; Schubel and Hirschberg 1978). Some even characterize this body of water by inferring it is made up of monotonous or abundant, mainly euryhaline marine fishes (Hedgpeth 1957). I am like- wise at a loss when referring to this stratified euryhaline zone or habitat which flood or freshwater runoff waters convert into a purely fresh- water habitat (Pritchard 1967a). Is it simply an extension of the fresh- water zone or should some new termi- nology be applied to this temporary zone, habitat, or condition? The unsettled definition of what is fresh water (Gunter et al. 1974) rages just as that of what is an estuary. For many years fresh waters were defined as those of 0.2 to 0.05 percent (Valikanges 1933; Dahl 1956) even though an international attempt was made to classify fresh water as those of 0-0.5 ppt salinity (Sympo- sium in Classification of Brackish Waters 1958). Kinne (1964, 1967) presented good overviews to the prob- lem. Gunter et al. (1974) and Odum (1953) presented excellent reviews of the physiological and environmental influences on estuarine fishes which can be extended to what happens to a fish which finds itself suddenly "trapped" or subject to a runoff freshwater intrusion area of a stream or river. I will not resolve, here- in, the question of whether such fishes should be referred to as eury- haline, oligohaline or some other designation (Gunter 1942, 1956; McHugh 1964; Gunter et al. 1974) but add to the list of known occurrences of fresh water and marine fishes that we know live in such waters, with comments on their sizes, and possibly interacting factors. METHODS The fishes encountered in the runoff zone of the major rivers of North Carolina were captured during the past 12 years (1968-1980) by various sized anchored gill nets and 8.0-13.5-m semiballoon otter trawls. Gill net sets were usually for 24 hr and trawl tows were for 0.25 to 0.5 hr duration. Specimens captured by gill net, unless too damaged by crabs or decayed by high summer water tem- peratures, or otter trawl were pre- served in the field in 10 percent formalin for later study and/or in- clusion in the fish collection at the Institute of Marine Sciences, Morehead City, North Carolina. Environmental variables of water temperature, oxygen, current speed, tide state, salinity were recorded by Taylor temperature thermometers (°C) , direct reading YSI oxygen (ppm)-tem- perature probes, and A/0 ref Tacto- meters for salinity in ppt. Fish lengths were recorded as standard lengths unless a total (tonguefish) or fork length (sturgeon) was more representative . DESCRIPTION OF NORTH CAROLINA RIVERS AND SOUNDS Schwartz and Chestnut (1973), Williams et al. (1973), and Williams 283 and Deubler, in part (1968), compiled the seasonal isohalines of the sound and coastal waters of North Carolina. The rivers that empty into the coast- al sounds (Figure 1) are most af- fected in early spring, especially March or April, when runoff (the re- sult of rains or melting snow up- stream) is highest. The major water- sheds of North Carolina, from north to south, are the Chowan-Roanoke, Albemarle Sound, Pamlico-Pungo River, Neuse River, Bay River, Newport Riv- er, White Oak River, New River, and Cape Fear River (Figure 1). These likewise feed into the major sounds of Albemarle-Currituck, Croatan, Roanoke, and Pamlico. Numerous smaller sounds exist south of Pamlico Sound but they are usually short in length or subject to more oceanic in- fluences than freshwater runoff (Figure 1). Most of the major rivers of North Carolina have extensive wa- tersheds and are usually 10m or less deep. The Cape Fear River, in the southern portion of the state, is the largest and is dredge-maintained upstream at 13 to 15m to Wilmington, North Carolina. Albemarle and Currituck Sounds are typically freshwater habitats during most of the year. Spring freshet runoff of these freshwaters extend 28 km into the low saline 8 ppt to 20 ppt Croatan and Roanoke Sounds thereby carrying fresh waters southward to Oregon Inlet (Figure 1). During the late fall (November) sa- line waters from Croatan and Roanoke sounds may extend into and along the lower eastern third of Albemarle Sound . The Pamlico-Pungo rivers are usually saline from near Washington and Winsteadville , North Carolina. Spring or sudden runoffs lower these 10 ppt to 17 ppt waters to 0 ppt for distances of 60 and 15 km respective- ly. The short 5 km Bay River is not included in the discussions of this study as it usually does not have a clearly defined freshwater intrusion zone. Instead runoff waters flow out into Pamlico Sound as a layer over the highly saline bottom waters. The Neuse River is fresh-water to just downstream of Grifton, North Carolina. The affected area of spring freshwater intrusion moves 0 ppt salinity waters 35 km to the junction of the Neuse River with Pam- lico Sound. Surface waters of Pam- lico Sound, during hurricane or other heavy rains, have been found fresh the entire extent from west to east and often pour out the inlets in the outer banks as a definite visible water mass (Schwartz 1973). However, 7 ppt to 32 ppt salinities usually prevail within Palmico Sound (Schwartz and Chestnut 1973) . The Newport River is a short compressed estuary of 12 km and is subject to large saline intrusions from the nearby Atlantic Ocean (Hyle 1976). The freshwater runoff zone has extended downstream for 4 to 5 km from its confluence with the estuary near the "Crossrocks . " The White Oak River is a long shallow river subject to high saline intrusions from the nearby ocean in its lower courses. During runoff the vertical freshwater face has been moved downstream 15 km to Stella, North Carolina. The New River is another saline intrusion-influenced river, yet the runoff zone is often extended south- east of Jacksonville, North Carolina for 12 km. The Cape Fear River is a swift river which, in its lower 30 km, is subject to 2-m tidal influences. Cape Fear experiences the highest 284 JO so Figure 1. Major rivers and sounds of coastal North Carolina illustrating areas considered freshwater (/////), runoff or distrubed estuarine i MP and saline (S) habitats. 285 runoff of any watershed, 257,929 to 7,264,664 liters/mo and flows of 66 cm/sec have been recorded (Schwartz et al. 1979a, b). However, that area from Campbell Island, 9 km south of Wilmington, North Carolina, to the man-made cut, "Snows Cut," 15 km fur- ther downstream is often subjected to periodic freshwater runoff which pro- duces 0 ppt recordings throughout the 13-m deep waters for periods of 6 to 8 weeks (Schwartz et al. 1979a, b). DISCUSSION Hoagman and Wilson (1976), Lowe- McConnell (1975), and Schubel et al. (1976), have documented the natural or induced downstream shift of the oblique or vertical freshwater-saline interface of a coastal stream or river following a rain or hurricane. Others (Chesapeake Res. Cons. 1976) have noted the resiliency of these saline-depressed waters as they re- turn to nearly "normal" states within short or long intervals but have not resolved the question--is this dis- turbed zone a truly freshwater or some sort of hybrid habitat? Like- wise, what happens to the freshwater and marine fishes that are momentari- ly "trapped" within these temporary and rapidly chemically changing wa- ters (Aller 1978; McHugh I960)? It is to this unstable and temporary no man's land between fresh and saline waters that I now address this report. RESULTS To date only Schwartz (1964) has compiled a list of freshwater fishes that are known from runoff freshwa- ter-euryhaline waters. Gunter (1942, 1956) compiled a similar list for 150 marine fishes known from euryhaline waters. Otherwise the sporadic occurrence of a species is usually treated as a brief note that one or more characteristically freshwater or marine fish was encountered in a freshwater, euryhaline, or marine habitat or vice versa (Rohde et al. 1979). I now add to Schwartz's 28 (1964) and Gunter' s 150 (1942, 1956) species lists of fishes that 37 freshwater (Table 1) and 77 marine (Table 2) fishes, within 13 fresh- water and 38 marine families re- spectively, are known to frequent or live in "freshwater" runoff habitats within the major tributaries of North Carolina (Figure 1). Seven of the freshwater species were found in wa- ters that were or reverted to 22 ppt to 31 ppt salinities following run- off. These included the longnose gar (Lepisosteus osseus) , gizzard shad (Dorosoma cepedianum) , golden shiner (Notemigonus chrysoleucus) , white catfish (Ictalurus catus ) , brown bullhead (Ictalarus nebulo- sus) , mosquitofish (Gambusia af finis , and flier (Centrarchus macropterus) . Of these Schwartz (1964) had, else- where, collected the gar from 23.4 ppt, gizzard shad 22.6 ppt, golden shiner 14.4 ppt, and white catfish 14.5 ppt (Schwartz and Kendall 1968) waters. Twenty-five of the 37 fresh- water fishes were found in higher sa- linities, in North Carolina, than previously noted by Schwartz (1964). In some cases, such as the gizzard shad, mosquitofish, bluegill, and pumpkinseed, their occurrences were recorded as abundant. Most of the freshwater fishes (20) were rare cap- tures in the runoff zone, which re- verted to 1 ppt to 27 ppt salinities. Thirteen species were common to zones that had been lppt to 31 ppt salin- ity Nine centrarchids and eight cy- prinids were fishes that frequented the runoff disturbed areas for pro- longed periods of 6 to 8 weeks prior to their retreat upstream into "pure" freshwater habitats. No trend was evident of increased number or kind of fish inhabiting the runoff area. 286 TABLE 1. List of 37 freshwater fishes, within 11 families, known to occur In previously considered estuarine waters of North Carolina when subjected to periodic flood water runoff. Common-Sclent i f ic Name Watershed Max. Prev. New Sal . Che Alb r.im N Np WO Ne CF Sal. Lit. High Status Cars - Lepisosteidae Longnose gar - Lepisosteus osseus Bow fins - Amiidae Bowfin - Amia calva Herrings - Clupeidae Gizzard shad - Dorosoma cepedianum Mudminnows - Umbridae Eastern mudminnow - Umbra pygmaea Pikes - Esoc idae Chain pickerel - Esox niger Minnows - Cyprinidae Carp - Cyprinus carpio Silvery minnow - Hybognathus nuchal is Golden shiner - Notemigonus crysoleucas Ironcolor shiner - Notropis chalybaeus Dusky shiner - Not ropis cummingsae Spottail shiner - Notropis hudsonius Coastal shiner - Notropis petersoni Swallowtail shiner - Notropis procne Suckers - Catostomidae Creek chubsucker - Erimyzon oblongus Shorthead redhorse - Moxostoma roacrolepidotum Freshwater catfish - Ictaluridae White catfish - Ictalurus catus Blue catfish - Ictalurus furcatus Yellow bullhead - Ictalurus natal is Brown bullhead - Ictalurus nebulosus Tadpole madtom - Noturus gyrinus Margined madtom - Noturus ins ignis Cavef ishes - Ambly ops idae Swamp fish - Chologaster cornuta Pirate Perch - Aphredoderidae Pirate perch - Aphredoderus sayanus Livebearers - Poeciliidae Mosqultofish - Gambusia af finis Sunfishes - Centrarchidae Flier - Centrarchus macropterus Banded pygmy sunfish - Elassoma zonatum Bluespotted sunfish - Enneacanthus gloriosus Redbreast sunfish - Lepomis auritus Pumpkinseed - Lepomis gibbosus Warmouth - Lepomis gulosus Bluegill - Lepomis macrochirus Largemouth bass - Micropterus salmoides Black crappie - Pomoxis nigromaculatus Perches - Percidae Swamp darter - Etheostoma fusiforme Tessellated darter - Etheostoma olmstedi Sawcheek darter - Etheostoma serri f erum Yellow perch - Perca f lavescens X X X X X X X X 31 S X X X - - - - X 5 X X X 30 S X X 12 S X X 5 S X X _ _ _ 0 0 X 1 S X X - - 0 0 0 0 6 s X X X - - - - X 27 s - - - - - 0 - - 6 0 0 - - 0 - - X 2 X X - - 0 0 0 - 4 s 0 0 0 0 0 0 - X 3 X - 0 0 0 0 0 0 1 X _ X 9 s X X - - 0 0 0 - 8 s X X X X _ _ _ X 27 s 0 0 0 0 0 0 0 X 1 X X 5 - - X - - - - X 27 s X X 5 X 0 - - - X - - 5 X - - - - - 0 - 5 X X X _ X _ _ X 5 X X X X - - - X 24 0 0 - - X 0 0 - 2 X X X 5 S X X 7 X X X X - X - - 15 S X X X 7 X X X - X X - X 9 S X X X - - X - X 5 S X - - - - 0 0 X 1.3 X _ X _ _ _ 0 X 5 S X X - X 0 - - X 6 8 5 X X X 0 _ _ X s c R C C Abd R Abd C R C C C C 0 = not known from watershed = known in watershed but not collected in disturbed portion X = known from disturbed portion of watershed Cho = Chowan River Alb = Albemarle Sound, includes Currituck, Croatan and Roanoke Sounds Pam = Pamlico River and Sound N = Neuse River Np = Newport River WO = White Oak River Ne = New River CF = Cape Fear River Max, Sal. = Maximum salinity in which specimen was captured Prev. Lit. = Previous literature citation of either C (Gunter) or S (Schwartz) * = established new high for recorded salinity observation C = Common R = Rare \bd = abundant , yg = young S = Schwartz 1964 C ■= Gunter 1942, 1956 287 .... .,,.il.-i. .1 . ~r i.irlnr ...irr*. of Horlh Carolina . •• ppi *.»l in it in. l.ir pi . > > *«*),•< trd to period I ujlri ruoof I (See Tablr I for .■■plana! ion of s-iih.'l - 1 ^.^..n-S, !rnt III La»pri-i > - ff(i.'*i[on( Idao Sea laapres - Prt roayton narlnu-. Hrqu.lca Shar-s - Car: l> jt In n idae Atlantic ihirpnoif shark - Rh 1 zcpr ionodon >. I a. Skates - Rajidae Clearnose skate • Hal* eglantrrla o n St Ingra.a - Dasvat Idae Southern stlngrav - Dasvatls amerlcana 0 I) Allan', aayails aablna 0 0 Sturgeons - Ac Ipenserldae Atlantic sturgeon - Aclpensrr oavrhvnchus Freshwater Eels - Angulllidae Anerlcan eel - AriRullla rostraca Conger Eels - Cangrldae Conger eel - Conger oceanlcus 0 0 Snake Eels - Opblchth 1 dae Shrimp eel - Qphlchihus gosesl 0 0 Herrings - Clupeldae Atlantic menhaden - Brevoortla tvrannus Blueba.k herring • Alosa aestivalis Hickory shad - Alosa roedlocrls X X X X X X Alewlfe - Alosa pseudoharengus X X American shad - Alosa sapldlsslsa X X Threadfln shad - Dorosoma petenense Atlantic thread herring - Oplslhonema ugllnurn 0 0 KllChovlca - Ejigrau 1 Idae Striped anchovy - Anchoa liepsetus Bay ancfiow - Anchoa Bit .rhl 1 1 1 X X -he* - Batracholdldae Oyster toadflsh - Opsanus tap 0 0 Cllngfishes - Goblesocldae Sklllctflsh - Goblesox si rumsus 0 0 Codfishes - Cadldae Spotted hake - Urophycls reglus 0 0 Cusk-eels - Ophldildae Crested cusk-eel - Ophldlon welshl 0 0 Needlefishes - Belonldae Atlantic needlefish - Strongylura aatlna X X Kllllflshes - Cyprlnodoncldae Sheepshead minnow - Cyprlnodon varlegatus Banded kllllftsh - Fundulus diaphanus Mummlchcg - Fundulus heteroc 1 1 lus Striped kllllftsh - Fundulus aalalls Rainwater kllllftsh - Lucanla parva 0 0 X X 0 0 0 0 0 0 Sllverslde* - Atherlnldae Rough sllverslde - Heobras martlnlca Tidewater sllverslde - Nenldla heryllina Atlantic illversldc - Henldla menldla 0 0 X X 0 X Plpeflshea - Syngnat Mdae Lined seahorse - H 1 ppoc aapus erectus Chain pipefish - Syngnathus loulsianae 0 0 0 0 0 0 Snooks - Cent ropooldae Snook * CentroponuB undr 0 0 leaperar r Basses • Percichtl.vldae White perch - Korone aaerlcana Striped bass - Moron* saxatllls X X X X Sea Basses - Serranldae Black sea bass - Centropr 1st is striata 0 0 Blueflshes - Pomatomldae Blueflsh - PonatoBua saltatrlx 0 Jacks - Carangldae Crevalle jack - Caranx hippos Atlantic bumper - Chloroscotabrus chrysurus 1) l.\ 0 0 Snappers - Lul janldae Cray anapper * Lutlanua grlseus 0 X Hojarras - Cerreldae Spot fin mojarra - Euclnostomus argenieus 0 0 Grunts - Poaadasyldee Plgflah - Orthopristls chrysoptera 0 0 Porglea ■ Sparldae Sheepahead - Archoaargua probat a< ephe lus 0 0 Plnllih - Lagodon rhonboldes 0 u Druas - Sclarnldae Silver perch - Balrdlella chryaura Spotted seatrout - Cynoaclon nebulosua UeaWfUh - Cynoaclon regalia Spot - Leloatoaua xanthurua Southern klngflah - Mentlclrrhus atoerlcanua 0 0 0 0 o n 0 0 0 0 Atlantic croaker - Hlcropogonlas undulatua Red drum - Sclaenopa ocellata Star drua - Stelllfer lanceolatus 0 0 0 0 0 0 0 X -Ailletm - "ugl I Idae Striped mullet - Hug 1 1 cephalua hft, 1 1 r mu 1 I r t - Hugll cureaa X X 0 0 Staraaiera - Uranoecopldar Southern itargairr - Aatroacopus u-graecua 0 0 Coabtooih blennlea - Blenntldae Created blennv • Hypleurochl lua gealnatua Frr.ilcd Mrnnv - Hvpaob lenn lua lonthas 0 0 0 0 M"r--- F|, ir Ida* Fal aleeper • Doraltator aaculalus 0 0 ' .,r 1** -obi 1 Jar Lyra toby - Evorthodua Ivrlcua 0 0 Harrr, ,,.i .,.. ; ,. ■ i, ..,.», 0 0 Sh.rpiatl aobv - Cobionel lu. haatatua 0 0 Frvahvatfl gob) - (k>blonellua ahufrldil 0 0 NaWi) *. > ■ .-■ 1 ■ ..j. ' .... | 0 0 Buiterfiahaa - ttroautelda* Harveitflah - Peprllua alapldoiua 0 0 Eaaroblnt - rrt|lld*e llghead avaroblfl - Prionotua trlbulu* 0 X l*'"" f luundrri - l,,|MJir ifcellate.1 <; -.mU, «. , paatta quadroce] lata U 0 Ba. -m ' ■ . .: Fr Inged f loundet - El ropua croaaotua 0 0 Su«»ei f louMdel .■ . Ipnt alui X |) S.-u(h«m fl.-unJet P., , ,tlgma Br.^aJ 1 loundei F'.r . . i ,,..,. Wlnd.^panr ... 1 0 0 \i 0 •..-Ir, ...ieiJar Mot,<: hokei Tun,, i,, BjaeulatHa Tongue f 1 1 he . > r, ■ , I . . , i j „ Blackthrek tongue ft ah • Svajpnufu» plati, .i Abd Abd R (vg) Abd (yg) 2 88 Of the marine fishes found in freshwater runoff areas, all 77 list- ed (Table 2) were found in 0 ppt salinity waters for extended periods as long as six weeks. As expected, anadromous, catadromous , and diadro- mous fishes such as sturgeon, her- rings, shad, and eels also were abundant in the 0 ppt runoff water zones. Other abundant fishes within the runoff area were the bay anchovy; tidewater and Atlantic silversides; white perch; striped bass; bluefish (young) ; sheepshead (yg) ; pinf ish (yg); black drum (yg) ; striped and white mullet; summer, southern, and windowpane flounders; hogchokers ; and blackcheek tonguefish (Table 2). Thirty-seven of the 77 marine or euryhaline fishes were common to the various disturbed runoff watersheds of the state while only 15 were rare occurrences within these waters. Herrings (9 species), drums (7), and flounders (7) were the dominant groups of fishes captured in the run- off zones. Thirty-five of the 77 marine fishes occurred in 0 ppt wa- ters and had not been reported pre- viously by Gunter (1942, 1956). Of the fishes encountered with- in the runoff zone, most were small juvenile or one-year-old age class individuals. Some species, such as the drums and flounders, were known to migrate to low salinity nursery waters and hence their presence in the runoff zone could be accounted for by such behaviors (Marshall 1976; Weinstein 1979, 1980). None exhib- ited external signs of stress or ema- ciation as a result of their living in or encounter with the runoff zone. The presence or absence of several species within a watershed or the runoff area was also a function of zoogeography (Jenkins et al. 1972; Rohde et al. 1979) rather than run- off or environment, as North Carolina lies at the junctures of many coastal north and south ranging species. Like Gunter et a_l. (1974) presence or absence of a freshwater or marine fish in a runoff area was dependent on many other factors, expecially water temperature and oxygen content. Water temperatures and oxygen levels, in most areas, of North Carolina were not limiting factors as most runoff occurred during months when water temperatures were low and contained high levels of oxygen (see Schwartz 1973; Schwartz et al. 1979a, b, six-year study of Cape Fear Riv- er) . Whether the varying chemical content of the various watersheds (Geraghty et al. 1973) played a role in the enhancement or demise of a species that was subjected to the sudden runoff waters remains unknown. Likewise nutrient change, as a result of runoff, is poorly known for North Carolina waters, the exception being the Neuse River where Hobbie and Smith (1975) noted the effects of runoff on various environmental parameters . Nichols (1977), Schubel and Hirschberg (1978), and many others have documented the enormous sediment changes that can occur in a body of water which has been subjected to river floods. Giese et al. (1979), reviewing the hydrology of the major estuaries of North Carolina, noted the effects of sediment "salting out" following freshwater inflow and cal- culated the number of days one could expect upriver portions of major rivers to be drastically affected by this phenomenon. Edgwald (1972) and Griffin and Ingram (1955) reviewed the sediments of coastal Pamlico and Neuse Rivers as a result of runoff. In turn, these sediments most likely caused changes in bottom chemical conditions (Aller 1978) or bottom 289 macroinvertebrates faunas (Schwartz et al. 1979a, b) on which the run- off zone fishes fed (Schwartz et al. 1980). Yet little information ex- ists, in North Carolina, on the fate of freshwater fishes, their transport into or within the runoff area, and how they are affected by sediments (Custer and Ingram 1974) . LITERATURE CITED Abbott, D.; Dawson, C.E.; Oppenheim- er; C.H. Physical, chemical, and biological characteristics of estuaries. Water and pol- lution handbook. New York: Mar- cel Dekker Inc., N.Y. Vol. 1.; 1971. 51-140. CONCLUSIONS AND RECOMMENDATIONS Many aspects remain unresolved in relation to fishes and the runoff zone and will provide research for the future. Thus, we must take the next step and test various species, under a variety of sudden or runoff conditions (Livingston et al. 1976), to determine why some cyprinids, centrarchids , clupeids, sciaenids, and bothids can exist in the unstable environment caused by freshwater run- off while others cannot. Only then will we begin to understand a runoff habitat, a fish's needs, and how we can best assure its survival in these rapidly changing runoff waters and habitats . ACKNOWLEDGEMENTS Aller, R.C. The effects of animal- sediment interactions on geo- chemical processes near the sediment-water interface. Wiley, M. L. ed. Estuarine interac- tions. New York, NY: Academic Press; 1978: 157-172. Carr, A.; Coin, C. J. Reptiles, am- phibians and freshwater fishes of Florida. Gainesville: Univ. Fla. Press; 1955: 341p. Caspers , H. Estuaries: Analysis of definitions and biological con- siderations. Lauff, G. H. ed. Estuaries. Washington, DC: Amer. Assoc. Adv. Sci., Pub. 83; 1967. Chesapeake Research Consortium. The effects of tropical storm Agnes on the Chesapeake Bay Estuarine System. Ches . Res. Consort. Publ. 54, Baltimore, MD: Johns Hopkins Univ. Press; 1976. Thanks are due Maury Wolff and Dennis Spitzbergen, N.C. Division Marine Fishes for their comments per- taining to freshwater inflow limits. Drs. A. F. Chestnut (IMS) and W. Hogarth (CPL) reviewed the manuscript. Helen Nearing typed the text while Brenda Bright typed the tables. Jackie Tate prepared Figure 1. Fund- ing, in part, was provided by the U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, University of North Carolina Research Council, N.C. Board of Science and Technology, Institute of Marine Sciences, and Carolina Power and Light Company. Custer, E.S., Jr.; Ingram; R.L. In- fluence of sedimentary processes on grain size distribution curves of bottom sediments in the sounds and estuaries of North Carolina. Univ. No. Caro- lina Sea Grant Publ. UNC-SG-74- 13; 1974. 88p. Dahl, E. Ecological sedentary bound- aries of Poikilohaline water. Oikos 7:1-23; 1956. Douglas, N.H. Freshwater fishes of Louisiana. Baton Rouge, LA: Claitor's Publ. Div. ; 1974. 290 Edgwald, J.K. Coagulation in estuar- ies. Univ. No. Carolina Sea Grant Publ. UNC-SG-72-06 ; 1972: 204p. Geraghty, J.J.; Miller, D.W. ; von der Leeden, F.; Troise, F.L. Water atlas of the United States. Washington, New York: Water Info. Center Publ. Port 1973; 119 p. Giese, G.L.; Wilder, H.B.; Parker, G.C., Jr. Hydrology of major estuaries and sounds in North Carolina. U.S. Geol. Surv. Water Res. Investig. 79-46, 1979; 175p. Griffin, G.M.; Ingram, R.L. Clay min- erals of the Neuse River Estu- ary. Sediment. Petrol. 25(3): 194-200; 1955. Gunter, G. A list of the fishes of the mainland of North and Middle America recorded from both freshwater and sea water. Amer. Midi. Nat. 28(2) : 305-326; 1942. Gunter, G. A revised list of eury- haline fishes of North and Mid- dle America. Amer. Midi. Nat. 56 (2):345-354; 1956. Gunter, G. ; Ballard, B. S.; Venka- taraniah, A. A review of sa- linity problems of organisms in Central States Coastal area sub- ject to the effects of engineer- ing works. Gulf Res. Rep. 4(3): 380-475; 1974. Hedgpeth, J.W. The classification of estuarine and brackish wa- ters and the hydrographic limits. Rep. 11 Nat. Res. Comm. 1951: 49-56. Hedgpeth, J. W. Estuaries and la- goons II. Biological aspects. Hedgpeth, J. W. ed . Treatise on marine ecology and paleocology. Vol. 1, Hedgpeth, J. W. ed. Mem. 67 Geol. Soc. Amer. Vol. 1; 1957: 643-729. Hoagman, W.J.; Wilson, W.L. The ef- fects of tropical storm Agnes on fishes in the James, York, and Rappahannock Rivers of Virginia, The effects of tropical storm Agnes on the Chesapeake Bay Estuarine System. Chesapeake Res. Consort. Inc. Publ. 54; 1976: 464-477. Hobbie, J.E.; Smith, N.W. Nutrients in the Neuse River Estuary. Univ. No. Carolina Sea Grant Publ. UNC-SG-75-21; 1975: 183p. Hoar, W.S.; Randall, D.J. eds . Fish physiology. VIII. Bioenergetics and growth. New York: Academic Press, 1979. 786p. Hyle, A.K. , II. Fishes of the New- port River Estuary, North Caro- lina, their composition, season- ality, and community structure. Chapel Hill, N.C.: Univ. No. Carolina; 1976: 192p. Jenkins, R. E.; Lachner, E. A.; Schwartz, F.J. Fishes of the central Appalachian drainages: Their distribution and dispersal, Holt, P. C. ed. The distribu- tional history of the Southern Appalachians Pt. Ill Vertebrates. Blacksburg, Va . ; 1972: 43-117. Kinne, 0. The effects of tempera- ture and salinity on marine and brackish water animals. II. Salinity and temperature salinity combinations. Ocean- ogr. Mar. Biol. Annu . Rev. 2: 281-399; 1964. Kinne, 0. Physiology of estuarine organisms with special reference 291 on salinity and temperatures. General aspects. Amer. Assoc. Adv. Sci. Publ. 83:525-540; 1967. Lauff, G.H. editor. Estuaries. Amer. Assoc. Adv. Sci. Publ. 83, 1967. 757p. McHugh, J. L. Management of estu- arine fisheries, Smith, R. F. ; Swartz, A. H.; Massman, W. H. eds. A symposium on estuarine fisheries. Washington, D.C: Amer. Fish. Soc. Spec. Publ. 3. 1966: 133-154. Livingston, R. J.; Cripe, C. R.; Laughlin, R.A. ; Lewis, F.G., III. Avoidance responses of estuarine organisms to storm water runoff and pulp mill effluents, Estuarine processes, Vol. 1. New York: Academic Press, Inc., 1976: 313-331. Livingston, R. J.; Kobylinski, G. J.; Lewis, F.G., III; Sheridan, P.F. Long-term fluctuation of epi- benthic fish and invertebrate populations in Apalachicola Bay, Florida. Fish. Bull. 74(2) : 311- 322; 1976. Livingston, R. J.; Sheridan, P. S.; NcLane, B. G. ; Lewis, F. G.,III; Kobylinski, G. J. The biota of the Apalachicola Bay system: Functional relationship, Pro- ceedings of a conference on the Apalachicola drainage system. Fla. Mar. Res. Publ. 26; 1977: 75-100. Lowe-McConnell , R.H. Fish communi- ties in tropical freshwater. New York: Longman. 1975: 337p. McHugh, J. L. Estuarine nekton. Lauff, G. A. ed . Estuaries. Washington, DC: Amer. Assoc. Adv. Sci. Publ. 83; 1967. Myers, G. S. Freshwater fishes and West Indian Zoogeography. Annu. Rept. Smiths. Inst. Publ. 3451: 339-364 for 1937; 1938. Myers, G. S. Use of anadromous, cat- adromous and allied terms for de- signating fishes. Copeia 1949 (2):89-96; 1949a. Myers, G. S. Salt-tolerance of fresh- water fish groups in relation to zoogeographical problems. Bidjr. Dierkande (Leiden) 27:315-322; 1949b. Myers, G. S. Freshwater fishes and East Indian Zoogeography. Stan- ford Icthyol. Bull. 4(1):11-21; 1951. Marshall, H.L. Effects of mosquito control ditching on Juncus marshes and utilization of mos- quito control ditches by estu- arine fishes and invertebrates. Chapel Hill, N.C.: Univ. No. Carolina, 1976. 294p. Disserta- tion. McHugh, J.L. The pound-net fishing in Va . Pt . 2. Species composi- tion of landings reported as .menhaden. Comm. Fish. Rev. 22 (2) : 1-16; 1960. Nichols, M.M. Response and recovery of an estuary following a river flood. J. Sediment. Petrol. 47 (3) : 117 1-1186 ; 1977. Odum, H.T. Factors controlling marine invasion into Florida fresh- waters. Bull. Mar. Sci. Gulf. Caribb. 3:134-156; 1953. Pritchard, N.W. What is an estuary: physical viewpoint. Lauff, G.H., 292 ed. Estuaries. Washington DC: Amer. Assoc. Adv. Sci. Publ. 83; 1967a. Pritchard, N. W. Observations of cir- culation in Coastal Plain estu- aries. Lauff, G.H. ed . Estu- aries. Washington, DC: Amer. Assoc. Adv. Sci. Publ. 83; 1967b; 37-44. Rohde, F.C.; Burgess, G.H.; Link, G.W. Jr. Freshwater fishes of Croatan National Forest, North Carolina, with comments on the zoogeography of coastal plain fishes. Brimleyana 2: 97-118; 1979. Schubel, J.R.; Carter, H.H.; Cronin, W.B. Effects of Agnes on the distribution of salinity along the main axis of the bay and in contiguous shelf waters. Ef- fects of tropical storm Agnes on the Chesapeake Bay estuarine system. Chesapeake Res. Consort. Publ. 54; 1976: 33-65. Schubel, J.R.; Hirschberg, D.J. Estu- arine graveyards , climate change, and the importance of the estu- arine environment. Wiley, M. L. ed. Estuarine interactions. New York: Academic Press; 1978: 285-303. Schwartz, F.J. Natural salinity tolerances of some freshwater fishes. Underwat. Nat. 2(2): 13-15; 1964. Schwartz, F. J. Biological and envi- ronmental assessment of four navigation improvement areas to Croatan, Roanoke, and Pamlico Sounds, North Carolina. Wilming- ton, DL: Rept. U.S. Corps En- gineers. DACW 54-72-C-0047; 1973: 75p. Schwartz, F.J.; Chestnut, A.F. Hydro- graphic atlas of North Carolina estuarine and sound waters, 1972. UNC-SG-73-12 Sea Grant Publ.; 1973: 132p. Schwartz, F. J. Kendall, A. Lethal temperatures and salinity toler- ances for white catfish, for white catfish, Ictalurus catus , from the Patuxent River, Mary- land. Chesapeake Sci. 9(2): 103-108; 1968. Schwartz, F.J.; Morgan, S.; McAdams , M.; Sandoy, K. ; Mason, D. Food analyses of selected fishes cap- tured in Cape Fear estuary and adjacent Atlantic Ocean, North Carolina, 1973-1978. Carolina Power Light Co. Pts. 1, 2, 3, Morehead City, NC : Inst. Mar. Sci. 1980; HOOp. Schwartz, F. J.; Perschbacher , P.; McAdams, M.; Davidson, L.; San- doy, K. ; Simpson, C. ; Duncan, J.; Mason, D. A summary report 1973-1977. An ecological study of fishes and invertebrate raa- crofauna utilizing the Cape Fear River estuary, Carolina Beach Inlet, and adjacent Atlantic Ocean. Carolina Power Light Co. Morehead City, NC: Inst. Mar. Sci. XIV: 1979a: 571p. Schwartz, F. J.; Perschbacher, P.; McAdams, M. ; Simpson, C. ; San- doy, K. ; Duncan, J.; Tate, J.; Mason, D. An ecological study of fishes and invertebrate ma- crofauna utilizing the Cape Fear River estuary, Carolina Beach Inlet, and adjacent Atlantic Ocean. Annu. Rept. for 1978. Carolina Power Light Co. More- head City, N.C.: Inst. Mar. Sci. XV; 1979b: 326p. Symposium on the Classification of Brackish Waters. Venis 8-14 April. Centro Naz. Studi Talas- sograf. Consiglio. Naz. Rich- erche XI; Suppl . ; 1958: 5-248. 293 Valikanges, I. Uber die biologie der Ostee als Brakwassergebiet . Verh. Int. Ver. Theor. Angew. Limnolog. 6; 1933. Shallow marsh primary nurseries Weinstein, M. P. habitats as for fishes and shellfish, Cape Fear River North Carolina. Fish. Bull. 77(2):339-357; 1979. Weinstein, M. P.; Weiss, S. L. ; Hod- son, R. G.; Gerry, L. R. Re- tention of three taxa of post larvae fishes in an intensively flushed tidal estuary, Cape Fear River, North Carolina. Fish. Bull. 78(2): 419-436; 1980. Wiley, M. L. ed. Estuarine Inter- actions. New York: Academic Press, 1978. 603p. Williams, A.B.; Deubler, E.E., Jr. A ten-year study of meroplankton in North Carolina Estuaries. Assessment of Environmental Factors and sampling success among Bothid flounders and Penaeid shrimps. Chesapeake Sci. 9(1):27-41; 1968. Williams, A. B.; Posner, G.S.; Woods, W. J.; Deubler, E. E., Jr. A hy- drographic atlas of larger North Carolina Sounds. Univ. No. Caro- lina Sea Grant Publ. UNC-SG-73- 02, 1973; 129p. 294 CHAPTER 4 FLOOD PLAINS AND ESTUARINE PRODUCTIVITY: ENERGY TRANSPORT, FRESHWATER RUNOFF, AND BIOLOGICAL RESPONSE 295 VARIATION IN FRESHWATER INFLOW AND CHANGES IN A SUBTROPICAL ESTUARINE FISH COMMUNITY Thomas H. Fraser Environmental Quality Laboratory, Inc. 1767 S. Tamiami Drive Port Charlotte, Florida 33952 ABSTRACT INTRODUCTION Trawl-susceptible fishes have been sampled for five years in Char- lotte Harbor, Florida. During this period, freshwater inflow recorded on the Peace River has varied from the second lowest to near the mean flow for the past 49 years. The 12 most abundant of 43 taxa captured, com- prising about 98 percent of the total catch, were used in the detailed analysis with flow. Average seasonal abundance appeared to be inversely related to flow in the wet season and directly related to flow in the dry season. Strong correlations exist for flow in June and the average abundance for June through September, and also for December-January flows and the average abundance for December through May. Apparent cycles of flow with an average period of six years occur in each season. The wet season of 1977 may represent a minimum point in the wet season cycles. A predicted astronomic tidal effect with a period of 8.86 years reached a minimum in 1977. Relative abundance during the wet season of 1977 was higher than all other wet seasons and may have influenced abundances in the dry season of 1977-1978. In the Apalachicola drainage basin (Meeter et al., 1979), varia- bility in abundance may be affected by long-term periodic changes of regional (local) climate. The long- term data of Livingston et al. (1978) show a correlation between river flow and fish abundance. This study and others such as Livingston et al. (1976) in the Apalachicola estuarine system provide the nearest (geograph- ic) long-term data on fishes and physical factors to this study. A study of upper Charlotte Harbor has been underway for five years. Flow characteristics of the Peace River and the subtropical cli- mate of the estuarine area are much different (Taylor, 1974) from those described by Livingston and other workers for the Apalachicola, yet the faunas are similar. This report briefly addresses the following topics: (1) the rela- tionship of abundance in Charlotte Harbor to Peace River flow; (2) tem- poral variation in abundance; (3) the relationship of abundance to other factors, such as temperature; and (4) long-term patterns that might 296 exist in flushing. river flow and tidal A review of Charlotte Harbor characteristics and adjacent bodies of water can be found in Taylor (1974). Information on fishes in the specific area of this study can be found in Finucane (1966), and Wang and Raney (1971). Both studies des- cribe seasonality and general fish community composition. Each study noted that decreasing abundance occurred with decreasing salinity as a result of high flows. Wang and Raney (1971) also noted the apparent influence of low temperature decreas- ing abundance in the winter. Their survey data show that the location of this study site is representative of the upper third of the harbor. This project was funded by General Development Corporation, Miami, Florida, as part of on-going studies of the aquatic biota, water quantity and water quality issues for Charlotte Harbor. Since freshwater flow is sea- sonal in Florida, the data are divided into dry season (October-May) and wet season (June-September) (Bradley 1972). Dry season rainfall is usually the result of cold fronts sweeping in from the north, while wet season rainfall is the result of local convective thunderstorms usually influenced by the position and strength of the "Bermuda high pressure system" in the Atlantic Ocean, providing an easterly flow of moisture across the state. Tidal information was based on the NOAA tide tables for 1971-1980. One ebb tide each day was chosen on the basis of greatest predicted range and examined for long-term variation in the average yearly range. The analysis assumed no effects by cli- matic conditions (wind speed and direction) or by high freshwater dis- charge . 3 Cubic meters per second (m /s) is converted to cubic feet per second (cfs) by multiplying by 35.31. METHODS RESULTS AND DISCUSSION Eight, two-minute repetitive 16- foot otter trawls were taken around Marker #1 (26°56.63'N, 82°03.60'W) in upper Charlotte Harbor about once a month to collect fishes and inverte- brates from bottom depths of 3. 5-4. 5m at night after twilight. The net was 5/8-inch mesh with 3/16-inch Ace mesh lining the bag and was towed at 1100 rpms by a 7.3m boat. Timing of the trawl commenced when the line reached 51m. In situ water column profile data were taken at 0.5m intervals for temperature, salinity, dissolved oxygen, pH and redox potential just before the series of trawls. Peace River flow was taken from the USGS station at Arcadia, Florida . PEACE RIVER FLOWS About 70 percent of all fresh water measured at USGS gauging stations to Charlotte Harbor passed Arcadia, Florida during this study. Peace River flow is highly variable both within a particular year and be- tween years. During the 49 years of record, annual mean flow ranged from 11.01 m /s in 1956 to 72.81 m /s in 1960, an increase of over six-fold in a 5-year period. While it may be fortuitous that the high and low records for 49 years occur within the same 5-year period, it dramati- cally illustrates changes in flow which can occur from year to year. 297 The river has distinct periods of high and low flow each year. High flow usually occurs from June through October, and low flow from November through May (Table 1). There is com- monly an order of magnitude differ- ence between low and high flow in a given year. Even within low and high flow periods, day-to-day flow varia- tion can be large with respect to the monthly or seasonal average flow. This natural variation in flow pro- duces large standard deviations asso- ciated with monthly mean flows. For example, the standard deviations as- sociated with each monthly mean flow during the period of record (1931- 1980) ranged from 74 percent to more than 100 percent. During this five-year study period, mean river flow was about 28 percent less than the mean for the period of record (Table 1). Seasonal pattern of the five-year mean flow was not very different except for late winter through early spring (February-April) . Examination, for example, of the wet season freshwater accumulation data provides a means of classifying each year (Figure 1). Two wet sea- sons, 1975 and 1977, were drier than the others. In 1979 most of the sea- son (June through August) was drier than average. However, flow in Sep- tember was more than 2.6 times the previous three months, resulting in a seasonal flow ranked as wetter than average (Table 2). Similar analyses were done for the dry season (Figure 2). The use of specific mean flows in comparison to the long-term means may be misleading, especially if the distribution of monthly flows is skewed, as in the case with Peace River flows. For example, the mean flow for June is 32.3 m /s (Figure 3), but 73 percent of the obser- vations are less than the mean. Dry season distributions as exemplified by December plus January are similar- ly skewed (Figure 4 and Table 1). Wet season median flow for the period of record accumulated by month was about 25 percent less than the long- term mean accumulation. The five years of flow data during this study generally fall on the low side of the median as well as the mean for the long-term frequency distribution. Only July 1978, August 1978 and Sep- tember 1979 exceed the long-term monthly average for wet seasons (Table 1). October 1979, November 1975, December 1977, January 1978 and 1979, February 1978, March 1978, April 1980, and May 1978, 1979, 1980 exceed the long-term average. Cyclical patterns in both the wet and dry season flows appear to occur over a 5 to 8 year period (Fig- ures 5 and 6) and average about 6 years. These longer term changes in flow are variable. However, since the high flow peaks in 1959-1960, wet season changes have been much less than those before 1959-60. The high flow peaks in the dry season have been relatively low since the last high peak in 1970. Cyclical patterns have been found by Shih (1975), for water levels in Lake Okeechobee and the Kissimmee River, and by Meeter et al. (1979), for the flow of the Apalachicola River. These oscillations are varia- ble but tend to repeat at intervals of 5 to 7 years. The fish data reported here coincide with low points for both the wet and dry seasons and for ascending trends. However, the high- er flows are much less then during other intervals. 298 00 3 O u js *j m r— on 1) C 3 S-l O to -a o eo U S-l < nj S-l CJ > ■ H OS OJ u 03 41 Cl< 0) x: CO 3 0) E Ln 00 ON CNJ CD *d- 1 — 1 i — i r~ 00 X co o O o^ < — i 1 — 1 C\J CNJ CNJ OO i — 1 i — 1 — i — i >! C\J o CJ! 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LL- < ro +-> CO CD CD IS) CD oo 299 XI oc 3 o 1-1 -E u-1 r- 00 <7> cn«> to h-r*- r»- cncn en a. 8i o < 5 3 Z 3 E o u 4-1 c o «J 0J 4-1 u 3 S-l o 3 o tw*ax NOiivnnwnxv 3 CD S-i > o 0) ea B S-i o 3 e 3 u o < 3 C3> 00 r-~ ■r-H O^ 300 3 Table 2. Ranking of Mean flows (m /s) of the Peace River from highest to low- est for wet and dry season at Arcadia, Florida, from June 1975 to May 1980. Rank Highest to Lowest Mean Flow 1 2 3 4 5 Mean Flow (1975-1980) Period of Record (1931-1980) Mean Flow Median Flow June - September October - May 3 Rankings for Period of Record. Wet Season Dry S Year 2 eason Mean Year Mean Flow Flow 1978 53.2 (18)3 1979-80 24.3 (16) 1979 46.5 (23) 1977-78 19.3 (26) 1976 45.1 (26) 1978-79 15.3 (30) 1975 30.4 (37) 1975-76 12.5 (34) 1977 21.8 39.4 56.9 45.7 (45) 1976-77 7.8 15.9 20.7 19.3 (39) 301 ,h4o«x Nouvirmnoov oo 3 o M -C *-> LO r^- o> rH E 0 s- 4-1 W _ C o £ t/) 03 < OJ s w >. » S-i T3 I lT> < Jh O ' 4-1 K 3 o 3 i — i 4-1 » u 01 *j si 3 E -C U3 > ■H - OS o 1) w o s OJ Oh M 4-1 O i 1/3 c S-i u, ,_ 302 LU < UJ S/£W MO"ld NV3W i e > x> S o ■H 4-> 3 XI •H S-l CJ c O) 3 cr CJ S-l 4-1 •o C! co O +J = z u a d >-> u o 4-1 3 o 4-1 fl CO en ■ 00 S-l •H UJ tH 4-> 303 < UJ >- u in o v u c «3 O 00 on S o u u CO 3 C 03 1-1 OJ CJ a o 3 o «5 > CD C ■3," Ho S/fW MOId NV3W X3 304 o .00 O 0> o <0 en < UJ >- o m en O en -O (-1 o pq « u S-l < S-l > ■H (J a< OJ -C j-> Sj o s o c o w OJ in 0) c = 0) 00 « s-l > ca c •H > o 1 1 i o o o CM T O T O T O nr o CM 03S/£lN in cn aj t— ' s-i 3 S ac o •H S-l fn 4-1 305 -8 < LJ >- -I o to T3 o Pn T3 «S O S-l < S-l > •H 04 » n -o c 03 OJ E OJ 00 « S-i > nj OC C •H > o E Sj M » T" O 00 s 1^ o o T o o CM 03 S /£W • CM vO (V) CU i-i S-l 3 E 00 o •i-l S-i 306 TIDES Tidal flushing in Charlotte Harbor is subject to long term cycles. One of these cycles lasts for 8.86 years with a 4.43 year span for coincidence of perigee and the farthest northerly and southerly dis- placement of the moon relative to earth's equator. An analysis of the maximum predicted daily ebb-tide range from 1970 to 1980 suggests that the average annual ebb-tide range can vary by about 10 percent or 6 cm. The minimum range occurred in 1977. Flushing in Charlotte Harbor, as influenced by river flow and tidal exchange apparently was near a mini- mum in 1977. A dry season followed by a dry, wet season should result in evaporation exceeding precipitation, coupled with low river flows and a minimum exchange between the estuary and gulf, salinities should rise in the harbor. The longest duration of high salinities occurred in 1977 (Figure 7) . FISH ABUNDANCES Mean abundances for the five years averaged by month show the annual tendencies for each species (Table 3). The very dry, dry season of 1976-1977 was followed by an extremely dry, wet season (Tables 1 and 2). During the driest wet season (1977) seven taxa (L. xanthurus , A. felis , ■ L. rhomboides , B. marinus , T. P. scitulus maculatus , and plagiusa) showed abundances not ex- ceeded in any other wet season (Table 4). Bagre marinus showed the great- est dry season abundance in the following dry season, unlike the other two species more common in the wet season. Three of these four taxa with usual dry season preference (L. rhomboides , S. plagiusa , and P. scitulus) showed abundance in the following dry season greater than all other dry seasons (Table 5). The presence of L. rhomboides during the past five years was basically re- stricted to the wet season of 1977 and the following dry season. Influence of one season's abun- dance on the following dry season appears to be of short duration. Species abundances in the following dry season, 1977-1978, were apparent- ly influenced by the unusual wet sea- son abundances. However, this dry season was also relatively wet and that may have been a confounding influence. The wet season of 1978 showed no apparent influence from the preceding wet or dry seasons of 1977- 1978. The wet season of 1976 was usually low in relative abundance (Table 4). This may be the result of early and high sustained flows that produced adverse conditions or rates of change in Charlotte Harbor salin- ity and dissolved oxygen (Figure 7). Flows greater than those observed in June 1976 have occurred about 27 per- cent of the time (Figure 3). This could mean that relative abundances may be as low as or even lower than those observed in 1976 for the upper part of the harbor about 27 percent of the time. Among the abundant taxa, some species were not collected during some seasons. Two species were not collected at all during the wet sea- son of 1976 and another three species were represented by a total of five specimens (Table 6). In the 1975 wet season three taxa were rare and two were absent. One to three taxa in the remaining wet season were rare or absent. One to four taxa were rare during dry seasons. Taxa frequently showing seasonal rarity were L. rhomboides , B. marinus and E. gula. Lagodon rhomboides probably is not a 307 en so IT) O sO - I . V s-l 0) c u 3 <0 i-l E C nj >» ■H C en C o > 0 . 01 jj o ai XI CO 1^ UD O LD CM i-H i— I CO CO CO «* >- cm ro O t-H =C cm *3- r-. ud 0> a, 3 o; cm en co ■— i =E i— i v CM o CM «*■ CM ** CM CO OJ in en *$■ r— i n o ■3) O CM OO 4-1 a « TJ Ol a o 3 d — 03 03 TJ 3 ■u 3 if. 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Eh CO fcj OQ 309 Table 4. The average number of specimens for the 12 most abundant benthic fishes in upper Charlotte Harbor by ranked wet season for 5 years. SPECIES 1 Anchoa mitchelli 2 Cynosoion arenarius 3 Arius felis 4 Leiostomus xanthurus 5 Mentioirrhus amerioanus 6 Trinectes maculatus 7 Lagodon vhomboides 8 Bagre marinus 9 Symphurus plagiusa 10 Prionotus scitulus 11 Eucino 'storms gula 12 Bairdiella chrysura Wet Season: June - September. 1 R 2 A N K 3 4 5 978 1979 1976 1975 1977 420 91 44 82 92 71 178 41 567 273 0 216 4 11 255 34 82 3 0 271 19 23 4 27 8 3 11 5 9 27 2 <1 <1 0 26 5 37 1 6 67 3 2 3 1 26 11 <1 0 2 30 1 12 0 8 1 3 6 <1 <1 8 310 Table 5. The average number of specimens for the 12 most abundant benthic fishes in upper Charlotte Harbor by ranked dry season for 5 years. RANK SPECIES 1 1979-80 2 1977-78 3 1978-79 4 1975-76 5 1976-77 Anahoa mitchelli. 83 206 251 184 124 Cynosoion arenarius 27 9 74 3 2 Arius fetis 158 25 21 < 1 1 Le-iostomus xanthurus 2 22 55 2 132 Mentioirrhus amevicanus 16 11 75 22 6 Tvi-nectes maculatus 14 12 37 5 10 Lagodon rh.orribovd.es <1 56 < 1 < 1 4 Bagre marinus 5 12 1 < 1 < 1 Synrphurus plagiusa 5 19 6 10 6 Prionotus seitulus 6 17 3 6 8 Eucino stomas gula 17 15 < 1 13 1 Bairdiella chrysura 7 7 1 4 < 1 Dry Season: October - May. 311 ^-i n CO r-< r-H CO o 00 (3 \r, r- ~ . — OJ a = >-) 1-1 o U-t w 0) 4-1 to T3 (b S- .-H o ft — E u M to CO W o CO >J zr lt> lti <—* •-< u O •H O 4-1 4-1 (J 01 •H si -d 4-1 4-1 a 4-1 aj o jO Jj 4-1 to OJ c a T3 d 3 TO TO 4-> a CO o o w E TO 01 CM 0! i-1 >1 OJ — Jd 4-1 > ~ <+H TO o I o 5 00 ta as i— ' < >> m , 2 vO jd 00 «J o CO CO CO Tl O .-I crt i — i i-h O CO o ."» •<■> «•-. o to to § 3 •»> Sj tj i: 3 3 T 1 3 oj r-~ ■H r4 ^- CO r^ CO CO o o OJ OJ OJ UD O co m CTt t— ' m OJ O I — <3" ^J- O O i£> OJ «4D ^d" LO O OJ CO 1^ to ts ■ •§ tj to 3 •»4 o s. 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CTi en o >- a CO X CM CM C\J CM CM CO h- QJ CD c_) CD C CO CO CM 1 — 1 LD CTl ■=d- S- "O zs - CT> CTl CTl CTl CTi o E CM ! CO T3 u-) d d l-i x O CO 4-1 r- 1 U CO o •H w 05 CO 0) CD u U CO CD CD 0C0-, CO M CD CD > 4-1 < 4-1 O X 00 c CD ■H H J4 X C CO CO H u CO X CO 0) z CD O C-. cn c I/) co co o CTi ^d- CM LD =3 s- co CD 00 r-. CT> CTi CTl LD cn LD CTi CTi +-> C/1 Cl) 3 iz o ;r _J < Q" C) 4-> c ) +-) i (/) u_ CD -C CD • i — re 316 o 8* 00 1 X o (- < o f- 15.2 15 .3 18. 9 24.6 z o 1 If) (J UJ 2 < FEB. MAR. &PRIL MAY CO 0> < o ~5 < Id UJ CO > < >- 2 tr 1 Q o o o 00 T" o o N 8 o o CVJ 30NVQNn9V 1VN0SV3S NV3W 0) J3 ~ o oo d d r- 0) o ( T3 S-l r^ d .d r-~ 3 +J i — i X> CO S-l o + C X> CO S >> 01 <1J o 6 u r^ 0) d CO co m o II s~~, ° CO X X -d o\ 73 71 d d 1 o o o m g •H * r-~ +J 1-1 5 co CO d o* z S-* ^ oo < 0) w d -> •H 3 o ,— 1 O (/j co CD o *-H S- . o 01 \ S-l 2uj CO t, a ° co ■v ,— 1 01 ■H >, o O J3 u '""> CO (XI ^ * U. o 3C CO +J d •H o o ■g * a, -I (J -G (U « li. 0) 4J • o Z Q u < d i-H d ^ o 4-1 -H Si 4-> S-l /-n CO c CD n) OJ 0) > X d -H •H CO •H u « J-l U-l ^. o Xi < u cd d u .T3 ■H <+-l co d Pm O S co 317 December to May. Flows in June and December plus January are poorly cor- related with subsequent seasonal flows for the period of record (R values less than 0.3). Perhaps long-term trends might occur for abundances of fishes in the upper third of Charlotte Harbor as a result of specific variations in riv- er flow. If the general trends ob- served for this data set are descrip- tive for relationships between flow and abundance, then one might expect average abundance to follow the flows. Thus, for wet season average abundance would be inversely related to flow in June (Figure 8) and dry season average abundance directly re- lated to flow in December-January (Figure 9) . Comparisons of relative abun- dances showed that among the top six species in Apalachicola Bay (Sheridan and Livingston 1979), three were among the top six in Charlotte Harbor (Anchoa mitchilli Leiostomus xanthu- rus and Cynoscion arenarius) . In both estuaries mitchilli was most abun- dant. The abundance pattern of A. mitchilli was apparently different in Charlotte Harbor with peaks in Feb- ruary and June rather than October- November in Apalachicola Bay. Cynos- cion arenarius was abundant in Char- lotte Harbor during the summer with peaks in June and August, rather than May and August. Leiostomus xanthurus was abundant in Charlotte Harbor from April through August with peaks in April-May and July, rather than in March. the end of declining temperature in the dry season, were correlated with fish abundance. 2. Extremely dry, wet seasons are accompanied by obvious increase in the abundance of very common species as well as the appearance of species not abundant during wetter wet seasons. 3. Changes in abundance during extremely dry, wet seasons may in- fluence abundance in the following dry season. 4. Extremely cold temperatures can temporarily influence abundance and presence periods . of taxa for short 5. Long-term periodicity in river flow may average about six years for both wet and dry seasons. The amplitude in flows may be quite variable . 6. Coincidence of other regu- lar long-term cycles such as tidal flushing may enhance environmental changes produced by fluctuating river flow. 7. It seems reasonable to expect some supra-annual oscillation in fish abundance related to changes in flow. The limits of variation are not clear, for the data only approach the known low-flow spectrum but are not even close to the known high-flow spectrum. CONCLUSIONS AND RECOMMENDATIONS Upper Charlotte Harbor 1. Year-to-year variation in river flow, particularly during the beginning of the wet season and near Charlotte Harbor and Apalachicola Bay 1. At least some of the more common taxa in both estuaries show abundance patterns that are dis- similar in time. These differences could be an expression of the varia- tion in the physical characteristics of the estuaries without implying 318 significant genetic populational differences. Although, depending on life history patterns, this may be one indication of major estuaries having distinct subpopulations such as described by Weinstein and Yerger (1976) for Cynoscion nebulosus . 2. Long-term periodicity in the flow of the Apalachicola River and the Peace River, while approxi- mately similar in duration, may be the result of regional (local) cli- matic effects. Thus, it may be im- portant to view general estuarine changes in periods much longer than the annual cycle in order to identify natural population oscillations from those resulting from man-made changes in flow. Southwest Florida Many of the observations for Charlotte Harbor, particularly in terms of the fauna, seasonal patterns of flow, long-term cycles may have analogues from about Estero Bay to Tampa Bay because of similar climatic and tidal conditions. populations in Apalachicola Bay, Florida. Fishery Bulletin 74: 311-321; 1976. Livingston, R.J. ; Thompson, N.P.; Meeter, D.A. Long-term varia- tion of organochlorine residues and assemblages of epibenthic organisms in a shallow north Florida (USA) estuary. Marine Biology 46:355-372; 1978. Meeter, D.A. ; Livingston, R.J.; Wood- sum, G.C. Long-term climatolo- gical cycles and population changes in a river-dominated estuarine system. In: Ecologi- cal Processes in Coastal and Marine Systems. Marine Science 10; New York: Plenum Press; 1979:315-338. Sheridan, P. F. ; Livingston, R. J. Cyclic trophic relationships of fishes in an unpolluted, river- dominated estuary in North Florida. Ecological Processes in Coastal and Marine Systems. Marine Science 10; Plenum Press; 1979:143-161. LITERATURE CITED Bradley, J.T.The climate of Florida. Climates of the United States; Water Information Center, Inc.; 1972; 1:45-70. Finucane, J.H.; Faunal production project. U.S. Fish Wildlife Service; 1966:18-20. Circular 242. Gilmore, R.G.; Bullock, L.H.; Berry, F.H. Hypothermal mortality in marine fishes of south-central Florida, January 1977. North- east Gulf Science 2 (2):77-97; 1978. Livingston, R.J. ; Kobylinski, G.J.; Lewis, F.G.; Sheridan, P.F. Long-term fluctuations of epi- benthic fish and invertebrate Shih, S.F.; Time series analysis and its application to water re- sources. Proceedings Second World Congress, International Water Resources Association; 1975; 5:223-236. Taylor, J.L.; The Charlotte Harbor estuarine system. Florida Scientist; 37 (4): 205-216. 1974. Wang, J.C.S.; Raney, E.C. Distribu- tion of fluctuations in the fish fauna of the Charlotte Harbor estuary, Florida. Mote Marine Laboratory; Charlotte Harbor Estuarine Studies; 1971; 1-56. Weinstein, M.P.; Yerger, R.W. ; Pro- tein taxonomy of the Gulf of Mexico and Atlantic Ocean sea- trouts , genus Cynoscion. Fish- eries Bulletin 74(3): 599-607. 319 RIVER-DERIVED INPUT OF DETRITUS INTO THE APALACHICOLA ESTUARY Robert J. Livingston Department of Biological Science Florida State University Tallahassee, Florida ABSTRACT The exact significance of river-derived particulate organic matter to estuarine biota remains in doubt. This is due, in part, to al lack of information regarding temporal (seasonal, annual) features of detrital loading. Quantitative as well as qualitative aspects of such detritus movement are probably an important feature of estuarine productivity. Long-term (5-year) studies of detritus movement into the Apalachicola estuary indicate that the timing of river flow peaks, together with changes in the wetlands vegetation along the flood plain and macrophyte cycles within the estuary, are important determinants of short- and long-term trends of the input of particulate organic matter. Research by the Florida State University Aquatic Study Group is currently addressing the specific response of estuarine biota to multiple climato- logical factors in an attempt to evaluate the biological significance of river flow into the Apalachicola estuary. INTRODUCTION River-derived freshwater input has various effects on receiving coastal systems. Some studies have described the production and movement of particulate organic matter in streams and rivers (Kaushik and Hynes, 1971; Hynes et al., 1974; de la Cruz and Post, 1977). De la Cruz (1979) has reviewed various aspects of the production and transport of detritus in estuaries . Post and de la Cruz (1977) estimated the trans- port of allochthonous particulate organic matter into a gulf coast bay and found that variation of net in- put depended on qualitative features of the leaf litter and the hydrolog- ical features of the system. Var- ious factors such as local meteoro- logical conditions, flow variation, litter fall and decomposition rates, river size and configuration, topo- graphy of the drainage system and physiography of the receiving estu- ary are all involved with the net input of organic matter to river- dominated estuaries. While various studies indicate that there is con- siderable seasonal and annual varia- tion in sediment discharge into bay systems, there is relatively little information concerning the qualita- tive composition of particulate organic matter as it moves into coastal areas and the temporal varia- bility of such movement. Such aspects of detrital flux could be of importance to the biological organization of the receiving estuary although there are few analyses that 320 take into consideration the timed in- teractions of upland watersheds and downstream dependent systems (Liv- ingston and Loucks 1979). Indeed, the biological significance of detri- tus fluxing in such systems remains in doubt (Haines 1979; Odum et al. 1979). The present study is part of a comprehensive long-term program to determine the functional relation- ships of hydrology (Meeter et al. 1979), energy relationships (White et al. 1979), food web character- istics (Sheridan and Livingston, 1979), and the timed interactions of river inflow and biological produc- tivity (Livingston and Loucks 1979) in the Apalachicola estuary. This paper will address specific questions related to the timing (seasonal, annual) of net inflow of particulate organic matter to the Apalachicola Bay system. MATERIALS AND METHODS A monitoring program was estab- lished to estimate short- and long- term trends of river-derived detrital input into the Apalachicola estuary. Sampling stations were established along the lower reaches of the river (Figure 1: stations 7, 8). Surface and bottom samples were taken at station 7; mid-depth samples at sta- tion 8. Once each month, from August 1975 to the present, water was pumped through a series of sieves (mesh size: 2.00, 1.00, 0.500, 0.250, 0.125, 0.090, 0.045 mm). All samples were taken on a falling tide. The amount of processed water depended on local conditions and varied from 50 to 1000 liters. Detritus samples were preserved in 2 percent HgCl„. Details of the laboratory procedures are given by Livingston et al. (1976). Dry weight (dried at 100°C for 24 hours) and ash-free dry weight (dried at 500°C for one hour) deter- minations were made for each sample (± 0.001 g) . All such samples are referred to as microdetritus , and only total values (i.e., all sieves) were used for this study. A qualitative estimate of the identifiable particulate matter in the estuary (macrodetritus) was made by analyzing monthly trawl tow sam- ples (32 replicate 2-minute tows with a 5-m otter trawl at 11 perma- nent stations; Figure 1) from Janu- ary, 1975, to the present. Samples were preserved in the field with 10 percent buffered formalin. In the laboratory, the detrital samples were identified according to origin (macrophyte or tree species, where possible), dried (100°C for 24 hours), and weighed (± 0.01 g) . Data were expressed as dry weight totals per sample. River flow data (Blountstown, Florida) were provided by the U. S. Army Corps of Engineers (Mobile, Alabama). Air temperature and local rainfall data were provided by the Environmental Data Service (National Oceanic and Atmospheric Administra- tion, Apalachicola, Florida). Rain- fall data in the Tate's Hell Swamp were provided by the East Bay for- estry tower (Apalachicola, Florida). RESULTS AND DISCUSSION Various studies (Livingston et al. 1977; Livingston and Duncan, 1979; Meeter et al., 1979) have indi- cated the relative importance of meterological conditions such as temperature, local rainfall, and river flow on the spatial and tem- poral aspects of habitat in the Apalachicola estuary. Such func- tions, over the study period (1975- 1980), are shown in Figure 2a. While the average summer high temperature 321 u Q) 4-1 O CO CO 3 H e 4-1 o cn » 4-1 lO 4J 4J o c * £> 01 ~. 3 !-i -Q 4-1 co •H Cfl 3 S-i 4-) 4-1 •a cn cn U a* •H ^H T3 c CO e ^H en cfl o 3 cn o 4J •H •H cn x; M c CJ 4J o cfl 01 •H H ~3 4-1 CO o cfl a. u 4-1 < a to CO 01 E cn 42 3 4J T3 4-1 C •H M-l CO »-l o 4-1 •V SJ 4-1 cn -3 U •H O CO cn 1-1 £ ?*, o U ^H •H T) B a • cO 01 i-l u >> cfl 01 4-1 M •H c 3 H 3 M cfl 0 •H 3 X! fe 3" cn 322 OOf O'fcZ oei o« 09 O'O O'Ofc O'OE 0'02 001 O'O OSI O1 OL OS O'O Oloas/euj WO UJ O 3 UJ Q O'ooz o 091 oo? ooe O'O*- 00 E 016 0 09 OOii 0 02 O'O 0 09 O'Oh 0 02 O'O 0UW/6w 01^/Buj OJ r-4 > >-l •r-l 03 OS OJ 03 XI ^ C o m u •h ao .3 d U -H 03 )-l r-4 G. 03 uj &. < ? > 1) 0) n«ca 1) 4-> 4-> W as S W £ r-l •i-i as d 4J ■h o E 4-> UJ >> 60 r-l as -H M as OJ TJ > C >> 03 OJ E I aj o E U U 03 i -d a «1 o . Si (J as " 60 -tJ £ ■H C/3 =1 M '" 1-1 u aj £ 4-1 OJ u S-l 3 w e o S-l [fl T3 o S-l ■H O = 00 .H = a\ »h 1_l w d 3 " 4-> -H Ui U -~^ 3 4-> 4J Mil •£, 3 "^ 60< o •H S4 ^ o u E 3 60 >> •- S-l w as ■H 3 ^5 as oj i-j X) w e o W S-l 3 4-1 4-1 03 3 >» • S-l 00 3 3 OJ XI o S-l u « 6 o u •H u S3 i— I OS < OJ jC J3 MH 4-1 •H ifl 3 — I 03 04 4-> E (/J 03 03 1—1 3 w 03 1) S-l rH 4-1 O, 323 did not vary to any extent, there was a progressive decline in winter low temperatures over the first three years with a minimum occurring during January, 1977. This was followed by progressively warmer winters (1978- 1980). Apalachicola River flow was seasonal with the highest daily peaks occurring during winter and spring months. After moderately high flows in 1975, there was a two-year period of relatively low winter-spring flows (1976-1977). This was followed by a series of high peaks in the early winter months of 1978 and spring of 1979 and 1980. Local rainfall peaked during summer-fall periods with rela- tively high rainfall in 1975. This was followed by a period of low rain- fall (1976 through 1978). Increased precipitation was observed in 1979 and 1980. These data indicate various phase differences in the climatological features of the study area as part of longer-term cycles (Livingston and Duncan 1979; Meeter et al. 1979). Analysis of the temporal varia- tion of macrodetritus and microdetri- tus is given in Figure 2b. A qual- itative determination of the macrode- trital component indicates spatial differences in detrital distribution (Livingston et al. 1977). Areas dominated by the Apalachicola River have winter peaks of wood debris and leaf litter derived from wetlands vegetation along the river flood plain. Dominant plant forms represented in the detritus include oaks (Quercus spp) , cottonwood (Populus deltoides) ,sweetbay (Liquid- ambar styraciflua) , tupelo (Nyssa aquatica) , river birch (Betula nigra) , and maples (Acer rubrum) . Detritus in the outer bay stations, farthest from river input, was dominated by various macrophytes including seagrasses and algae. Benthic macrophyte-derived detritus usually peaked in late sum- mer or fall, reflecting growth and decay patterns of Ruppia maritima, Ulva lactuca , Halodule wrightii , Vallisneria americana , and Gracilaria spp. A bimodal seasonal cycle of estuarine detrital peaks was super- imposed over a long-term trend that tended to reflect supra-annual varia- tion of river flow. The first sea- sonal peak of debris was absent dur- ing 1980 at which time river flow tended to peak later in the spring. There were indications that although the amount of debris in the bay tends to follow river flow conditions, the specific time of the year of river flooding is also an important factor in the amount of available detritus. The long-term trends of microdetritus were somewhat consistent with this pattern (Figure 2b) , and the highest levels of such particulate matter tended to coincide with maximal river peaking early in the year. (January-February). Such peaks in microdetritus usually were closely associated with river flow peaks in time whereas the macrodetritus showed differential lags as explained by Livingston et al. (1977). Thus, there were short- and long-term asso- ciations of available detritus and river flow conditions (i.e., seasonal peaks) that reflected qualitative differences in the form of the or- ganic matter as well as the seasonal distribution of river peak phenomena. Overall, peak detrital flows re- flected seasonal river flow patterns with major peaks occurring during winter-spring months. Such patterns of total detrital loading (flux) fol- lowed detrital concentrations (mg ash-free dry weight/m in the Apala- chicola River. A linear regression of micro- detritus and river flow by season (Table 1, Figure 3) indicated that there are seasonal differences in the relationship of detrital concentration and river flow. During summer periods, there is no 324 Table 1. Linear Regression (log/log) of total microdetritus (ash-free dry weight) and riverflow (m /sec) by month/year by Season (8/75-4/80). Station 7 (Surface) R R June-August 0.08 0.23 September-November 0.48 0.23 December-February 0.70 0.49 March-May 0.77 0.60 ot (significance) 0.39863 0.03469 0.00188 0.00057 Station 7 (Bottom) June-August 0.08 0.01 September-November 0.21 0.04 December-February 0.77 0.60 March-May 0.55 0.30 0.40243 0.22867 0.00037 0.02253 Station 7 (Mid-depth) June-August 0.35 0.12 September -November 0.19 0.04 December -February 0.64 0.40 March-May 0.68 0.46 0.11809 0.25542 0.00570 0.00397 325 * • . > CD < LU 5 U. o" LX LU < o 2 • * 6 > z> O < z UJ z I-' Q. Z> LU -5 (/> ■ ► • • * ► * ■ ► ■ • 'T- cn 1^ Q CM in -ojDjiu -shin jap 6| i *-> t/i B o u H-l c u J£ m j-> w r-4 nj JJ O 4-> -— ' U3 3 +J ■H l-l •U U •o o u u •H > E > U-l o^ o CO 1-4— !/J c o L. •H • ^™ U L. X! 4-> >» D) O S ^^^^^ o ^ "H 60 ^ o , r-l H \ o -H ^ « \^s in nj N ■H ° « " <3 ™ o "2 *j is n ^ ^S 1) M rv- " l-l 3 • w n M D r-~ u 3 d oo o •H -H P* 4-> 326 direct correlation of river flow and detritus in the system. By the fall, there is still no significant rela- tionship although there are occasion- al influxes of detritus with minor peaks in the river flow. By winter, however, there is a strong direct re- lationship between microdetrital loading and river flow peaks. How- ever, the winter regression differs from that of the spring detrital loading which, though significantly associated with river flow levels, requires higher river levels for com- parable concentrations and loading of detritus. This analysis indicates that the degree and timing of river flooding on a seasonal basis affects the level of detrital loading to the estuary. The key to the biological sig- nificance of the detrital flux into the estuary lies in the spatial/ temporal response of the estuarine biota. Such a response is not easily determined because of the natural variability of the system. Livings- ton (1978) and White et al. (1979) have described the experimental basis for the detrital-based energy system in the Apalachicola estuary whereby organic particulate matter and dis- solved nutrients are transformed into microbial biomass. Such energy is then utilized by a diverse macro- fauna. Sheridan and Livingston (1979) and Laughlin and Livingston (in review) have detailed some key components of the food web structure in the Apalachicola estuary. The detrital input is an important part of the system. The timed reaction of the biological components to climato- logical features such as rainfall and river flow have also been established (Livingston et al. 1977; Livingston and Loucks, 1979). There are various indications that seasonal and annual variation of river input is an important factor in the estuarine response. The results of this study indicate that the qualitative and quantitative aspects of detrital in- put into the estuary are dependent on a number of factors that vary throughout a given season, and from year to year. While the important detrital food web is closely asso- ciated with the timing and degree of river flooding, functional relation- ships remain undetermined and are currently under study. However, it is clear that, while the river is important with regard to bay produc- tivity, such relationships depend to considerable degree on climatological conditions, trophic response, and the natural history of various estuarine species . The data presented here are preliminary in that the biological response of the estuary remains de- pendent on various features of the estuarine habitat. Experimental studies are currently being carried out to determine the relationship of the estuarine food webs and com- munity structure with potential bio- logical-controlling features such as predation and competition. However, the results of this study indicate the importance of the specific timing (seasonal, annual) of clima- tological events relative to the quality and quantity of input of allochthonous detritus which moves into the estuary. Periodic (pulsed) movement of detritus is only one part of the biologically important fea- tures of habitat organization. A knowledge of the details of biologi- cal response to such environmental variables will be necessary if we are to understand the impact of anthropogenic alteration of the tim- ing and extent of river flow on receiving estuarine systems. LITERATURE CITED de la Cruz, A. A. Production and transport of detritus in wet- 327 lands. Paper presented at the National Wetland Symposium. Disneyworld Village, Lake Buena Vista, Florida; 1978 November 7-10; 1979. de la Cruz, A. A. ; Post, H.A. Pro- duction and transport of organic matter in a woodland stream. Arch. Hydrobiol. 20:227-238; 1977. Haines, E.B. Interactions between Georgia salt marshes and coastal waters: a changing paradigm. Livingston, R.J., ed. Ecological processes in coastal and marine systems. New York: Plenum Press; 1979: 35-46. Hynes, H.B.N. ; Kaushik, N.K. ; Lock, M.A.; Luch, D.L.; Stocker, Z.S.J. ; Wallace, R.R. ; Williams, D.D. Benthos and allochthonous organic matter in streams. J. Fish. Res. Board Can. 31:545- 553; 1974. Kaushik, N.K. ; Hynes, H.B.N. The fate of the dead leaves that fall into streams. Arch. Hydrobiol. 68:465-515; 1971. Laughlin, R.A. ; Livingston, R.J. Spatial/temporal variability in the distribution of the blue crab (Callinectes sapidus) in a north Florida estuary (in review) . Livingston, R.J. Effects of forestry operations (clearing, draining) on water quality and biota of the Apalachicola Bay system. Florida Sea Grant, Final Report; 1978; 400 pp. Livingston, R.J.; Duncan, J. Short- and long-term effects of for- estry operations on water quality and epibenthic assemb- lages of a north Florida estu- ary. Livingston, R.J., ed. Ecological processes in coastal and marine systems. New York: Plenum Press; 1979: 339-381. Livingston, R.J.; Loucks , 0. Pro- ductivity, trophic interactions, and food web relationships in wetlands and associated systems. Paper presented at the National Wetlands Symposium. Disney- world Village, Lake Buena Vista, Florida; 1978 November 7-10; 1979:101-119. Livingston, R.J.; Iverson, R.L.; White, D.C. Energy relation- ships and the productivity of Apalachicola Bay. Florida Sea Grant Program, National Oceanic and Atmospheric Administration (Final Report); 1976: 437 p. Livingston, R.J.; Sheridan, J.S.; McLane, B.G.; Lewis, F.G., III; Kobylinski, G.G. The biota of the Apalachicola Bay system: functional relationships. Liv- ingston, R.J.; Joyce, E.A., Jr., eds. Proceedings of the Confer- ence on the Apalachicola Drain- age System. Gainesville, Flori- da; 1976 April 23-24. Florida Department of Natural Resources, Mar. Res. Lab. Contr. #26; 1977: 75-100. Meeter, D.A.; Livingston, R.J.; Woodsum, G. Short- and long- term hydrological cycles of the Apalachicola drainage system with application to gulf coastal populations. Livingston, R.J., ed. Ecological processes in coastal and marine systems. New York: Plenum Press; 1979: 315-338. Odum, W.E.; Fisher, J.S.; Pickral, J.C. Factors controlling the flux of particulate organic car- bon from estuarine wetlands. Livingston, R.J., ed. Ecologi- cal processes in coastal and 328 marine systems. New York: Plenum Press; 1979: 69-80. Post, H.A.; de la Cruz, A. A. Litter- fall, litter decomposition, and flux of particulate organic material in a coastal plain stream. Hydrobiologia 55:201- 207; 1977. Sheridan, P.; Livingston, R.J. Cyclic trophic relationships of fishes in an unpolluted, river-domi- nated estuary in north Florida. Livingston, R.J. , ed. Ecological processes in coastal and marine systems. New York, Plenum Press; 1979: 143-161. White, D.C.; Livingston, R.J. ; Bob- bie, R.J.; Nickels, J.S. Effects of surface composition, water column chemistry, and time of exposure on the composition of the detrital microflora and as- sociated macrofauna in Apalachi- cola Bay, Florida. Livingston, R.J. , ed. Ecological processes in coastal and marine systems. New York: Plenum Press; 1979: 83-116. 329 DISCUSSION Question: What are the implications for water release in the Woodruff Dam? Answer: The Woodruff Dam is actually a flow-through system. They don't have a storage capacity. During the winter time it flows at the normal actual river flow. In fact, we modeled the river before and after and there is no difference in flow. The only difference has to do with the freshwater fishing along the river. During the low summer flows, I can tell you when everybody is turning their air conditioners on, because you've got big six-foot waves going down the river which are destroying the habitat of freshwater fishes which are trying to reproduce at that time. I would say that the only control would be relatively minor and possibly not even allowed because they have a certain legal amount of water that has to go over that dam. The only way they could help the situation is in the summer flows by not running it in at times when the freshwater fishes are try- ing to reproduce. Question: There's not a hydro- electric generator, is there? Answer: Yes, there is. Question: The only release of water that takes place in the summer is through the hydroelectric reserve? Answer: We've got other problems that are more pressing than regula- tion, I think. One would be the ac- tual allowance that the river be kept running. It has been projected that by 2005 the Atlanta area will have grown to such a size that we're not going to have any more flow out of the Chatahoochee which is one of the main parts of that system. That would mean that we're all going to be struggling for water. I have heard other papers that are telling the same thing. If there's one thing at this conference that has to be faced, it is that within the next thirty years we might not be getting any more flows that we're showing here. Certainly, these peaks are going to be knocked off that river. There's no doubt that they're going to be able to store enough water there for use, so that you're not going to be getting this peak anymore. This system is going to change. I think we can start to predict how it's going to change by recognizing the relationships we've got right now. As far as controlling the dam, I really don't think that's going to help much at this particular point. Question: There's one more point. With the effect of the dam do you basically have higher lows and lower highs? Answer: We've done a hydroelectric record on pre-dam and post-dam flows, and we cannot detect any serious changes in peaking except for minor changes in summer lows and perhaps, somewhat lower highs. Answer: Well, it goes through the hydroelectric system, yes, and they are generating electricity. You can watch the peak on weekends. Question: So, you've got a general raising of the lows and lowering of the peaks but it's not something real drastic? Question: If you could conceive that some kind of water regulation could take place on that river, what would you ask for? Answer: The Army Corps of Engineers predicted that the closer they get to the bay with the dams, the more winter peaks will be lowered. 330 Question: Generally, what do you want out of that river? Answer: I'll tell you what I want. I want to leave this system alone. I want it to work like it has always worked. I'll tell you why. It's one of the last functional systems we've got. Most of the other systems I've gone over have either been dammed or there's agriculture or pollutants or something else in the river. We can't find any pollutants here, and the river's still flooding. We've still got tremendous productivity. I'd like to see it all stay the same and study it and find out how it goes, and, then, I can help out, perhaps, in the Chesapeake where they don't have such base-line data. It is critical to have base-line data to see how the system functions because when you put man in these systems you change the system. The orchestra's not playing the same tune and it isn't predictable. Or, maybe it's too predictable. This is a national estuarine sanctuary. This is the largest, most ambitious estuarine sanctuary in the country. Eight percent of the people in this system would like to keep the system the way it is. That's another point. We've done a lot of work with educat- ing these people on how this works by going into schools, by going on radio and TV, and presenting the scienti- fic data to the public. Question: That's 2,000 square miles of your watershed. What about the other people up in Georgia and Alabama? Answer: I'll be quite honest with you. There's some people up there who have said this is going to be the next Ruhr valley of the south. They want to dam it and make this a major channel for industrialization. I don't think that should go on. I think it should still be a multiuse system. They can use it, but they don't destroy it for other people. Question: If there's a mechanism to get scientific data, can you get it in the hands of the right people to use it? I think that should be a question answered at this conference. Answer: Don't you think that's due partly to the fact that working on estuaries falls between the responsi- bilities of all the agencies? Question: It's doesn't escape all the agencies. I think it is a very valid question to ask. It's quite simply, yes, for us today. You talk about flows to the estuary deter- mined by places like Atlanta and the institutional interface is through agencies such as HUD, which provides grants for permissions to construct new housing developments and this type of thing. We have very weak methodology to input into that process. I'm from Galveston, Texas, now, and we're trying to deal with that question in the Houston area. So far it's a very slow battle. Furthermore, we don't even really know what we're trying to accomplish there . Answer: I think Bob Herbst touched on that, and I'd like to emphasize that the worst enemy we've had as far as constructing a system has been the Federal Government. Not just the Federal Government, but the Congress of the United States with the various edicts they have made over the years. Keeping that a deep channel has shown over one-half billion dollars for navigation alone. The flood plain insurance program actually encourages people to settle all through some of these sensitive flood plain areas and along our barrier islands which is another rather sensitive area. 331 They build bridges with federal funds out to our barrier islands. The last data I was showing you were purchased and actually paid for by the fisher- men in Franklin County, because I've not been able to get any sustained federal funding for any of this re- search. The one sustained group that has funded me has been a county that is considered to have the poorest per capita income in the state. I think our worst enemies are right here in Washington, D.C. Question: How do you propose to stop or slow down the influx of people to Florida? Answer: I don't want to slow them down. I want to put them in the right places. You could put a lot of people in that valley and not affect a thing. Question: You talk like it's up to the county commissions to regulate what happens. Answer: The point is though, I'm not trying to make it overly simple. There are outside agencies that are working, and there are also laws. These laws apply to these systems . If you have enough information on how this system works it makes it a little more difficult to destroy the system. I don't say it won't be destroyed. You can make it difficult if you have the answers already in the scientific literature. We're winning cases. They won that Red River thing because he had some in- formation and it was bought by the court. But you can't go in and say, "I'm an environmentalist, and I love this system, and I want it to go on the way it is." Or "I'm so and so from the Fish and Wildlife Service, and I'm a big man in Washington, and I want this system to stay the way it is. You can't do that. It doesn't work that way. Question: You've got a lot of answers on the upper Apalachacola and I'm impressed. How can you translate that into instruction or direction at the decision level in the remote area if it's affecting your particular aspect of the sys- tem? That's the problem we're facing. I had to go out and talk to HUD and tell HUD what I want. Answer: Each group has to solve that problem separately because each situ- ation is different. In our area we have established an estuarine sanc- tuary there. Through the sanctuary, we're now going to get new programs. We're going to apply them all the way up to Atlanta and make sure that the people all along that tri-river sys- tem know what's going on. 332 CHAPTER 5 MISSISSIPPI RIVER DELTA FRESHWATER INFLOW REHABILITATION 333 FLOW REGIME AND SEDIMENT LOAD AFFECTED BY ALTERATIONS OF THE MISSISSIPPI RIVER J. R. Tuttle Lower Mississippi Valley Division, Corps of Engineers A. J. Combe, III U. S. Army Corps of Engineers New Orleans District, New Orleans, Louisiana ABSTRACT The Mississippi River drainage basin includes all or part of 31 states and 2 Canadian Provinces cov- ering about 41 percent of the con- tiguous United States. The shape of the basin is much like a funnel with the spout entering the Gulf of Mexico in the State of Louisiana. Over the past several thousand years the Mississippi River has occu- pied and abandoned seven deltas re- sulting in progradation of the shore- line and development of a large low- relief deltaic plain in south Louis- iana. In its natural state, the river channel and its vast floodplain were used to convey all flows south- ward to the Gulf of Mexico following natural drainage patterns evolved over centuries of meandering by the river. Man's occupation of the val- ley brought with it extensive modi- fications to the river and its flood- plain. These modifications, which made it possible for man to survive and prosper in the valley, have changed the distribution of water and sediment in distributaries and major outlets entering the estuaries. Distribution of flow to the coastal area of south Louisiana has changed significantly over the past 140 years. A massive log raft re- moved by the State of Louisiana from the Atchafalaya River in the middle 1800' s and subsequent natural en- largement, hastened by flood control and navigation works, has resulted in the Atchafalaya River, a major dis- tributary of the Mississippi River, transporting about 25 percent of the discharge of the Mississippi. On the Mississippi, extension of flood pro- tection levees resulted in closure of three distributaries above New Orleans and confined water and sedi- ment to a well-defined leveed chan- nel. In the Atchafalaya Basin, de- velopment of basin guide levees con- fined floods to a leveed floodway and two outlets, Atchafalaya River below Morgan City and Wax Lake Outlet. In the past 30 years average suspended sediment loads in the Mis- sissippi River Basin have been re- duced about 50 percent. The natural process of sediment deposition in the Atchafalaya Basin has progressed from near the head of the Atchafalaya River in the late 1800' s to Atchafa- laya Bay, materially hastened by alterations in the basin. The middle reach of the Atchafalaya has experi- enced significant natural filling and 334 the formation of a new delta is oc- curring on the Louisiana coast ap- proximately 77 miles west of the modern bird's-foot delta of the Mis- sissippi . INTRODUCTION All runoff from the large drain- age basin of the Mississippi conver- ges in south Louisiana and exits into the Gulf of Mexico (Figure 1). Over the past 6,000 to 8,000 years the Mis- sissippi River has occupied several positions (Figure 2) resulting in progradation of the shoreline and development of a large low-relief deltaic plain in south Louisiana (Fisk 1952). The Atchafalaya Basin, a large lowland bounded by the high natural levees of the Mississippi and Bayou Lafourche on the east and Bayou Teche on the west, is the most promi- nent feature in the Lower Valley (Figure 3). Within the Atchafalaya Basin, the Atchafalaya Floodway and Atchafalaya Bay are currently experi- encing morphological changes on a grand scale (Figure 4) . Prior to the 1840' s, the Missis- sippi was the primary route for de- livery of water and sediments to the gulf. Discharges up to bankfull re- mained in the channel and exited into the gulf with the exception of minor percentages that diverted through distributaries. Discharges exceeding bankfull flowed generally southward through the Atchafalaya Basin low- lands and into the gulf through nu- merous bayous and outlets. Distribu- tion of flow and sediment is signifi- cantly different today. The Atcha- falaya River, a dynamic distributary of the Mississippi, has a distinct gradient advantage and is currently controlled to carry about 25 percent of the flow and sediment load of the Mississippi River. Flood flows now enter the Atchafalaya Basin in a con- trolled fashion, rather than through levee crevasses. Major natural dis- tributaries, Bayou Manchac, Bayou Plaquemine, and Bayou Lafourche have been closed by flood protection levees. This paper describes the natural regime of the river, reviews alterations of the Mississippi River drainage system, and discusses their effect on the flow regime and sedi- ment loads entering estuaries. NATURAL DRAINAGE PATTERN OF SOUTHERN LOUISIANA Estuaries of south Louisiana (Figure 5) can be divided into three zones: zone 1 lies east of the modern Mississippi River and its bird's-foot delta and includes Lakes Maurepas, Ponchartrain, and Breton Sound; zone 2 is bounded on the east by the Mississippi River and its delta and on west by the high natural ridges of the Lafourche system; and zone 3 is the broad Atchafalaya Basin bounded on the east by the Lafourche system and on the west by the natural higher levees of the former Teche delta system (Figure 2). In its nat- ural state, distribution of water and sediment to estuaries in zone 1 was via Manchac Bayou, a distributary located about 15 miles downstream of Baton Rouge, Louisiana, to Lakes Maurepas, Ponchartrain, and Borgne, and Pass A Loutre at the mouth of the Mississippi River; in zone 2 via Bayou Lafourche, a distributary located at Donaldsonville, Louisiana, and southwest pass at the mouth of the Mississippi River; and in zone 3 via the Atchafalaya River and Bayou Plaquemine, a distributary lo- cated at Baton Rouge, Louisiana. The 335 c ■H t/3 ■H OS a. U3 •H w •H S 3 OO ■H 336 Q S-i > •H OS a, CO CO 1) h S 00 Uh 337 NATURAL ATCHAFALAYA BASIN Figure 3. Natural Atchafalaya Basin. 338 RIG. 4 ATCHArALAYA BASIN fLOOOtMr HISTORICAL CONVERSION OF WATER AREAS TO LAND AREAS THROUGH ACCRETION RANCC 13 TO ATCHAFALAYA BAY Figure 4. Atchafalaya Basin Floodway. 339 6 H u > •H ~ 3 00 340 distribution system was periodically supplemented during high flows by various crevasses and breaks in the natural and later man-made levee systems of the lower Red and Missis- sippi rivers (Elliott 1932). NATURAL FLOW REGIME For discharges up to bankfull the Mississippi River and four major distributaries, delivered flow to the estuaries. Estimated bankfull capa- city of the Mississippi River in 1851 was about 1,000,000 cf s . The com- bined peak discharge of Bayous Pla- quemine and Lafourche in the 1858 flood was 45,000 cubic feet per sec- ond (cfs), with the peak of Bayou Plaquemine being three times greater than Bayou Lafourche. No measure- ments were available for Bayou Man- chac or Atchafalaya River, however, based on early descriptions, Bayou Manchac had less capacity than Bayou Lafourche and the Atchafalaya River was choked by a massive log raft probably rendering it ineffective ex- cept during flood overflow. In times of flood, the Atchafalaya Basin (zone 3) served as the major outlet for ex- cess flood waters. Flows entered the Basin by overtopping banks, through the Atchafalaya River and Bayou Pla- quemine with some contribution from Bayou Lafourche, and through cre- vasses in natural levees on the west bank of the Mississippi from Red Riv- er Landing, Louisiana, to Donaldson- ville, Louisiana. Zone 1 and zone 2 received excess flood water through crevassing of natural levees which occurred frequently but not neces- sarily in every flood. NATURAL SEDIMENT DISTRIBUTION There is no reliable data upon which to make a determination of the magnitude of sediment loads trans- ported by the Mississippi River in its natural state. Measurements of suspended sediment were taken in the 1800 's at various locations on the river; however, the equipment used and the random sampling procedures followed make the results of those measurements of little practical use (Paper H 1930). It is assumed that the distribution of sediments was about in proportion to the distribu- tion of flows previously described. It is very probable that only a minor portion of the sediment loads entered distributaries, and that accompanying excess flood flows ever reached the vicinity of the coastline due to the low topographical features of zones 1 , 2 , and 3. ALTERATIONS OF THE MISSISSIPPI In recent history numerous al- terations of the Mississippi have been accomplished, each designed to fulfill a specific objective and ne- cessary for man to continue to sur- vive and prosper in the Mississippi River Valley. Not all alterations affect the flow regime and sediment load of the river, at least not sig- nificantly, and some alterations af- fect only the distribution (the route of discharge and sediment) rather than the magnitude of discharge and sediment loads. Those alterations considered significant include: levees, reservoirs, bank stabiliza- tion, and removal of Atchafalaya Riv- er log raft. 341 LEVEES The primary effect of levees on flow regime and sediment loads enter- ing estuaries has been confinement of discharges and sediment loads to three specific all stage outlets: Head of Passes and vicinity; Atcha- falaya River, south of Morgan City, Louisiana; and Wax Lake Outlet, west of Berwick Bay, Louisiana and one flood relief spillway, Bonnet Carre Spillway located just north of New Orleans, Louisiana (Figure 6). Levee extensions closed Bayous Man- chac, Plaquemine, and Lafourche in 1828, 1866-1867, and 1903, respec- tively. BANK STABILIZATION It has been estimated that cav- ing banks in the lower Mississippi River, prior to stabilization, yield- ed annually about 1,000,000 cubic yards of material per mile of river (Shen 1971). The program of bank stabilization in the lower Missis- sippi River steming from the 1928 Flood Control Act is about 76 percent complete. Recently, estimated vol- umes of material caving into the riv- er annually in the Vicksburg Dis- trict, are a fraction of the previous estimate, therefore, revetments are probably responsible for a substan- tial portion of the reductions in suspended sediment loads experienced on the Mississippi River and tribu- taries . RESERVOIR REGULATION Over the past 50 years several hundred single and multipurpose re- servoirs have been constructed in the headwaters of the major tributaries of the Mississippi. Currently these reservoirs control the runoff from about 58 percent of the basin area. Reservoirs trap large percentages of incoming sediment loads, therefore, it is possible that reservoirs have influenced reduction of suspended sediment loads on the Mississippi. REMOVAL OF ATCHAFALAYA RIVER LOG RAFT In 1831 Captain Shreve made a cutoff in the Mississippi River across the neck of Turnbull Island (to aid navigation) which left the mouth of the Red River and the head of the Atchafalaya River in an ox- bow lake with a two-way connection to the Mississippi River (Figure 7). The Atchafalaya, at this time, was an ineffective distributary of the Mississippi, choked by a massive log raft covering 20 miles of its length. A few years after Shreve' s cut off, local interest, and later the State of Louisaina, undertook removal of the raft for the purpose of develop- ing navigation on the Atchafalaya. Their efforts were eventually suc- cessful and the Atchafalaya was re- portedly open by 1855 (Latimer 1951). Because of a distinct gradient ad- vantage, the Atchafalaya enlarged rapidly near its mouth causing lands previously exempt from overflow to be submerged annually by the increasing volume from above. Local interest responded by building levees, con- fining flows, and closing outlet channels, causing the Atchafalaya to scour its bed, thus, hastening the inevitable natural enlargement of the river. While the upper Atchafalaya was rapidly enlarging, the middle and lower reaches of the Atchafalaya Basin were experiencing rapid and ex- cessive sedimentation, signaling the beginning of a deltaic process. In 1932 efforts to hasten the develop- ment of an efficient well-defined single channel through the deteri- orating reach were undertaken. The present, channel is a culmination of those efforts. 342 Figure 6. 343 SHREVES CUT-OFF DEVELOPMENT OF OLD RIVER Figure 7. Shreves Cut-Off, FIG. 7 344 Development of the Atchafalaya Floodway levees system was undertaken in 1932, which confined flow to about 50 percent of the original floodplain width from the leveed Atchafalaya River to just above Morgan City Reach. In 1942 work was undertaken to construct a channel through Teche Ridge for the purpose of diverting 20 percent of the Atchafalaya flow to western Atchafalaya Bay. Subsequent, natural enlargement has increased the diversion to about 30 percent of the Atchafalaya flow. EFFECT OF ALTERATIONS ON FLOW REGIME AND SEDIMENT LOADS Bay, south of Morgan City, Louisiana; and Atchafalaya Bay, west of Morgan City, Louisiana. The present distribution of flow to coastal Louisiana is 70 percent at Head of Passes; 21 percent, Atcha- falaya Bay, south of Morgan City; and 9 percent, Atchafalaya Bay, west of Morgan City. The high-level outlet, Bonnet Carre Spillway, diverts flood flows in excess of 1,250,000 cfs to Lake Ponchartrain. This outlet has been operated six times, 1937, 1945, 1950, 1973, 1975, and 1979. In summary, alterations have re- duced flows in the Mississippi, in- creased flows in the Atchafalaya, closed three distributaries, and con- fined flows to three all-stage out- lets and one high-level-flood outlet. FLOW REGIME SEDIMENT LOADS Alterations of the Mississippi River, its drainage basin, and adja- cent floodplain have been extensive, but, the effect of these alterations has been distribution of flow rather than influence on the annual volume of flow delivered to the estuaries. Removal of the Atchafalaya River log raft and subsequent alterations which hastened the natural enlargement pro- cess have resulted in the Atchafalaya River now carrying 30 percent of the total latitude flow of the Missis- sippi under normal conditions (Figure 8). This includes all of the Red River and portions of the Missis- sippi . Levees have closed distributar- ies and confined flood flows of the Mississippi River drainage system to three all-stage outlets and one high-level outlet. The all-stage outlets are Head of Passes, south of New Orleans, Louisiana; Atchafalaya At the latitude of Red River Landing, Louisiana, sediment data have been collected at the following stations: Red River Landing, Louis- iana, (September 1949 to date); Simmesport, Louisiana (September 1951 to date); Morgan City, Louisiana (1965 to date); and Wax Lake Outlet, Louisiana (1965 to date). The data consist of suspended sediment meas- urements which measure that portion of sediment load that is suspended in the water from the water surface to about 3 feet above the riverbed. The measurements at Red River Landing represent the sediment loads transported by the Mississippi. The average annual load at this station for the period 1950-1959 was 307 mil- lion tons for an average annual vol- ume of flow of 332 million acre- feet. For an equivalent volume of flow the average annual load for the period 1966-1976 was 170 million 345 ■ nnmj cici UU 1 — ■ LU LU — I 031 H 31dW BAIU 03 Id 010 H1NI C961 ca ^ ^ lu X"-1 ^ CO _j L i_i i ICO /OS / LU 1 °~ gfe 00 6 LU LL. LU Cfl DOWN THE MISSISSfPPi RIV! AT TARBERT LDG., 1 »— LU C_3 LU 1 ao cn CD r- cn CD CO cn to cn oo cn CD CO cn cvi cn cn 2 o fan 1+4 O d o 3 •H u W cnooi — coud^s-cocsj M01J JO 39VlN33H3d u 3 oo 346 tons, a reduction of about 50 per- cent. At Simmesport, Louisiana, on the Atchafalaya River the average annual sediment load for the period (1951-1959) was 134 million tons for an average annual volume of flow of 122 million acre-feet. For an equi- valent volume of flow, the average annual load for the period (1966- 1976) was 70 million tons, a reduc- tion of about 50 percent. Based on records available, channel stabiliza- tion and other features have reduced average annual suspended sediment loads delivered to south Louisiana by 50 percent. The Atchafalaya Basin is unique and very complex relative to sediment loads and distribution. As previous- ly mentioned, removal of the raft at the head of the fledgling Atchafalaya initiated the natural developments of that stream as a major distributary of the Mississippi. As scour en- larged the upper channel, rapid sedi- mentation took place in the middle reach of the basin. Development of a reasonably well-defined channel in the middle reach (1932-1968) de- creased the rate of sedimentation in that reach, causing more sediments to be transported to Atchafalaya Bay. By the 1950' s significant influx of sediments to the Atchafalaya Bay begin to occur (Roberts et al. 1980) indicating that it took approximately 100 years for the initial channel development to push through to the coast of Louisiana, even though the process was materially hastened by alterations in the basin. Since 1950 the influx of sediment to the bay has increased dramatically. The refer- ence cited above indicated that for the period 1973-1975 only 17 percent of the total average annual suspended sediment was retained in the Atcha- falaya Basin with 65 percent carried by the lower Atchafalaya River and 19 percent carried by Wax Lake Outlet, resulting in the rapid filling of Atchafalaya Bay. SUMMARY AND CONCLUSIONS Under natural conditions water and sediment, contained within the channel and including the Red River which was a tributary of the Missis- sippi, flowed to the gulf by way of the Mississippi River and four pri- mary distributaries: Bayou Manchac, Bayou Plaquemine, Bayou Lafourche, and the Atchafalaya River. In time of flood, excess water and sediment flowed from the Mississippi and Red Rivers southward to and through nu- merous bayous into the lakes and swamps along the coastline of Louis- iana . Alterations of the Mississippi and Atchafalaya Rivers over the past 140 years have significantly affected the distribution of flow and sediment loads entering the estuaries of south Louisiana. The most significant al- terations were: removal of the Atcha- falaya River log raft and subsequent alterations which hastened natural processes; confinement of flood flows by levees limiting discharges to three specific outlets; and those al- terations that affected a 50 percent reduction in average annual suspended sediment loads transported by the Mississippi and Atchafalaya rivers. Review of alterations and their affect on flow regime and sediment loads entering estuaries has led to the following conclusions: a. The average volume of flow delivered annually to south Louisiana has not been affected by alterations. 347 b. The total (Mississippi plus Atchafalaya) average annual suspended sediment loads delivered to south Louisiana have decreased about 50 percent since the early 1950's. flood control and navigation. U.S. Army Corps of Engineers, Mississippi River Commission, Vicksburg, Mississippi; 1932: 3 Vol. c. The average annual volume of water transported by the Mississippi below the latitude of Red River Land- ing has decreased due to increased diversions to the Atchafalaya River since the middle 1800' s. d. Developments in the Atcha- falaya Basin, following actions of the State of Louisiana to establish navigation on the Atchafalaya River in the middle 1800' s, have signifi- cantly hastened the natural enlarge- ment processes in the Atchafalaya Basin and Atchafalaya Bay. Fisk, H.N. Geological investigation of the Atchafalaya Basin and the problem of the Mississippi River diversion. U.S. Army Corps of Engineers, Mississippi River Commission, Vicksburg, Missis- sippi; April 1952: 2 Vol. Latimer, R.A.; Schweizer, C.W. The Atchafalaya River study. U.S. Army Corps of Engineers, Miss- issippi River Commission, Vicks- burg, Mississippi; May 1951: 3 Vol. e. Channel enlargements in the middle and lower reaches of the Atchafalaya Basin have been instru- mental in channeling sediments to the Atchafalaya Bay, reducing the poten- tial for overbank sedimentation in the Atchafalaya Basin above Morgan City, and causing acceleration of a significant marsh area in Atchafalaya Bay. LITERATURE CITED Paper H, Sediment investigations on the Mississippi River and its tributaries prior to 1930. War Department, U.S. Army Corps of Engineers, Mississippi River Commission, St. Louis, Missouri; 1930. Roberts, H.H.; Adams, R.D.; Cunning- ham, R.H.W., Evolution of sand- dominant subaerial phase, Atcha- falaya Delta, Louisiana. Am. Assoc, of Petroleum Geologists Bull. 64:2; Feb. 1980. Elliott, D. C. The improvement of the Lower Mississippi River for Shen, H.W. River mechanics. 1971, 2 Vol. 348 ATCHAFALAYA DELTA: SUBAERIAL DEVELOPMENT ENVIRONMENTAL IMPLICATIONS AND RESOURCE POTENTIAL Robert Cunningham Center for Wetland Resources, Louisiana State University Baton Rouge, Louisiana ABSTRACT A major geologic event in the history of the Mississippi delta sys- tem is now in progress along the cen- tral Louisiana coast. Because of a distinct gradient advantage, the main distributary of the Mississippi Riv- er, the Atchafalaya River, is rap- idly developing a subaerial delta in Atchafalaya Bay, 130 miles (200 km.) west of the modern bird-foot delta. The subaerial growth of the new delta is being monitored with remote sensing techniques, land and hydro- graphic surveys and a sediment sampl- ing program. Initial formation of new land in the Atchafalaya Delta has been found to occur sporadically with accretional periods coinciding with flood pulses ofl the river. Approxi- mately 12.39 mi (32 km ) of new land had been formed by 1976 with addi- tional accumulations following the 1979 flood. A prototype data collection pro- gram is currently underway to provide data for a study of estuarine hydro- dynamics and sediment transport in the bays and near offshore areas of the Atchafalaya-Vermilion estuarine complex. Accretional impact lines include subaerial deltaic sedimenta- tion, subaqueous bay fill and mud- flat-marsh building in a region for- merly characterized by shoreline re- treat. These impacts are presently producing negative effects on open water habitats, but the potential for improved marsh and aquatic nursery ground environments and expansion of human habitats in the vicinity of Morgan City far outweighs loss of open bay habitats. The Corps of Engineers is considering several pro- ject alternatives for mitigation of present impacts and management of future delta growth. INTRODUCTION A remarkable new geologic event in the 6,000 year history of the Mis- sissippi delta complex is currently unfolding in Atchafalaya Bay, along the central Louisiana coast near Mor- gan City, Louisiana (Figure 1). Con- struction and abandonment of a major delta lobe of this system occurs on a time scale of about 1,000 years (Kolb and Van Lopik 1966). Since the present 800-year-old bird-foot Balize Delta has prograded far out onto the continental shelf, the Mississippi River has lost much of its efficiency for delivering water and sediment to the gulf. 349 FIG.1 Regional setting , Atchafaylaya Bay. 350 The Atchafalaya River, a vener- able distributary of the Mississippi River, has a distinct gradient advan- tage because of its shorter route to the Gulf of Mexico. Aided by man's activity, the Atchafalaya has rapidly increased its proportion of the Mis- sissippi's latitudinal flow to more than 30 percent during this century. The result has been the rapid devel- opment of a new delta 130 miles (200 km) west of the modern Balize Delta. The new Atchafalaya Delta is the fifth major event in the 6,000 year history of the delta system. The delta is building into an area where the effects of deltaic sedimentation have been absent for over 2,000 years (Frazier 1967). This region, tradi- tionally characterized by shoreline retreat, is experiencing a reversal in the landloss trend and local shore line progradation. Scientists at Louisiana State University, Center for Wetland Re- sources became intensely interested in this delta-building episode be- cause of the opportunity to study the estuarine hydrodynamic, geological and biological processes taking place. Through a cooperative effort with the Corps of Engineers, NOAA Sea Grant and Naval Oceanographic Pro- grams, active monitoring of delta- building processes began in 1975. The purpose of this paper is to address the development of the Atcha- falaya Basin and the new delta, its impacts, and possible management al- ternatives to deal with these im- pacts . ATCHAFALAYA BASIN DEVELOPMENT This new episode of delta build- ing started about 1950 (Shlemon 1975), but since the initial delta growth took place in the subaqueous (underwater) environments of Atcha- falaya Bay, there was little aware- ness of this event during the first twenty years of development. In 1973 definite subaerial delta lobes and artifically created spoil islands began to appear at Atchafalaya Bay and by 1975, at the end of three con- secutive high water years, in 1975, the emerging deltas had grown to en- compass several square miles of the bay. Associated environmental and engineering problems emerged quickly. Fisheries were disrupted as sediment- choked freshwater spread throughout adjacent bays and marshes. Channel shoaling impeded navigation on the heavily used waterways near Morgan City. Rapid changes in the flowline also created alarming flood control problems for Morgan City. The Atchafalaya River was a distributary of the Mississippi as far back as the 1500' s (Fisk 1952). During the middle and late 1800' s, flow from the Mississippi and Red Rivers into the Atchafalaya was in- creased by the removal of a log raft and dredging of a navigation channel. By the mid-1900' s a natural channel had become so well established through the diversion that the volume of flow increased at an alarming rate. Total capture of Mississippi River flow seemed inevitable because of the Atchafalaya' s shorter route to the Gulf of Mexico and its decided gradient advantage. Old River con- trol structure, built in 1963, was designed to prevent this possibility by limiting the diversion into the Atchafalaya to approximately 30 per- cent of the flow of the Mississippi. Because the lower course of the Atchafalaya River contained a network of lakes and swamp catchment 351 basins, much of the sediment load carried by the increasing flow was deposited in these areas before it reached Atchafalaya Bay (Figure 2). Progressive sedimentation began to drastically reduce open water areas in the basin. Grand and Six Mile Lakes in the lower basin filled rap- idly during the period from the 1930' s through the 1960's. By 1975 only small remnants of open water remained . It was not until the early 1950' s that sedimentation at the coast began to initiate noticeable effects. This occurred only after the channel through the basin had developed well enough to convey silts and small amounts of sand to the bay. During the 1950' s and 1960's silts and clays transported to the coast began to be deposited near the mouths of the outlets in the bay. By the early 1970' s a thick platform of silty clay deposits covered not only Atchafalaya Bay, but adjacent off- shore areas as well. As much as six feet of bay fill was deposited between 1952-1972 as the delta front advanced to the Point Au Fer shell reef (Shlemon 1975). Prior to 1972 very little sand-sized sediment was being deposited in Atchafalaya Bay. The years 1973-75 were unprece- dented flood years on the Atchafalaya River (Figure 3). River discharge doubled normal conditions during the peak flow periods. More importantly, both the volume and size distribution of sediments reaching Atchafalaya Bay changed dramatically (Table 1). An extraordinary increase in the amount of sand, scoured from the basin and transported to the bay, was noted during this period (Roberts et al. 1980). ATCHAFALAYA DELTA DEVELOPMENT CHANGES IN BATHYMETRY Bathymetric changes in Atcha- falaya Bay over the decade 1967-77 have been impressive. The 1967 map (Figure 4) shows silty distal bar de- posits represented by the 4-foot con- tour were beginning development in the bay. By 1972 these deposits cov- ered most of the bay. Following the 1973-75 high water years, an extensive network of sandy distributary mouth bar deposits had emerged in both Wax Lake and lower Atchafalaya River lobes (Figure 5). Approximately 15 mi of these de- posits had become subaerially exposed (Rouse et al. 1978). A seaward ex- tending, branching network of dis- tributary channels had also devel- oped . The 1977 bathymetric chart emphasizes the tremendous volume of coarse-grained sandy material de- posited during the 1967-77 decade. Figure 6 illustrates the areas of net accretion/erosion and their magni- tudes in Atchafalaya Bay over the period (Roberts et al. 1980). Areas with accumulations of 7-8 feet are generally regions of dredge spoil accumulation. Small areas of bay scour are noted, due primarily to the increasingly restricted routes by which water can exit the bay. As the initial subaerial phase of delta growth was monitored, using repetitive satellite imagery, it was noted that substantial increases in bar exposure became apparent only after major flood crests (Figure 7). Little growth was noted between these flood peaks. For example, 6 mi (15.5 km ) of bar exposure are shown on this image (A) following the 352 □ ACCRETION 19171930 ACCRETION 19301960 ACCRETION 1960-1975 FIG. 2 History of lacustrine delta fill, Grand and Six Mil Lakes. After Roberts et al. 1980. 353 500 2 m o 73 74 75 76 77 78 79 FIG. 3 Average monthly discharge of Atchafalaya River . USCOE data. CD Boy ihorelina t 1 0 and above □ 0 lo -2 :-- CD -2 lo 10 ■10 FIG. 4 Bathymetric map, Atchafalaya Bay, 1967 (contours are in feet). USCOE data. 354 FIG. 5 Bathymetric map, Atchafalaya Bay , 1977 (contours are in f«et). USCOE data. FIG. 6 Net accretion and erosion in Atchafalaya Bay, 1967-77 (contours are in feet ).After Roberts et al. 1980. 355 26 SEP 73 17 FEB 74 < o a o •-* o o nj o -h o •— < c/i h in .-< a. ■H tfl a) QJ J-. E QJ 6 > G O 357 record flood of 1973. In 1974 little additional deposition, except for dredge material, was noted because of the absence of an extreme flood crest (B) . In 1975 another major flood peak doubled the bar exposure to about 12 mi (30 km ) (D) (Rouse et al. 1978). Another high water year was ex- perienced in 1979 (Figure 3). Data for a new topographic survey are cur- rently being compiled. Preliminary indications from recent aerial photo- graphy and island transects show marked aggradation or vertical build- up of existing islands, welding of several islands, and a reduction in the number of active distributaries. Only a small increase in the area of the delta was noted, indicating the possibility of a new phase of deltaic development — a subaqueous ma- rine delta, forming just seaward of the Point Au Fer shell reef (Van Heerden 1980). VEGETATION RESPONSE The following table lists the acreages of vegetation colonizing the emergent islands: Natural Sp< sil Island Islands Vi ?getation 1974 216 790 1975 380 796 1976 1,117 1,783 1977 no no change change 1978 1,113 1,783 (1 acre = 0.0040 km ) Vegetation progradation showed a marked increase during a year fol- lowing major flood, as was evident the year following the 1975 flood (Sasser personal communication). A slight decrease was noted during sub- sequent low water years due to a lack of sediment nourishment and erosional processes. Figure 8 il- lustrates vegetation progradation, covering approximately 4.5 mi (11.7 km ) of the delta as of the end of the 1978 growing season. Preliminary results from a 1980 vegetation inven- tory indicate another large increase in acreage resulting from the 1979 flood. All developing habitats in the delta have been documented as being freshwater habitats (Montz 1978). REGIONAL IMPACTS OF DELTAIC PROCESSES During the investigation of sub- aerial delta growth in Atchafalaya Bay it became apparent that the im- pact of the sediment-laden discharge from the Atchafalaya River extended far outside the confines of Atcha- falaya Bay. In fact, estimates indi- cate that less than 50 percent of the fine-grained sediment transported to the bay is actually deposited there. Satellite imagery, available since 1972, tends to support this conclu- sion (Figure 9). Turbid flows were found to impact as little as 300 mi during Low discharge and as much as 1,200 mi during flood periods. To study these regional impacts, Landsat images collected between 1972-1977 were studied. Turbidity patterns which appear on the imagery were excellent indicators of the major components of estuarine circu- lation when correlated with a mathe- matical model tuned with wind and 358 ATCHAFALAYA BAY FIG. 8 Vegetated areas. Atchafalaya delta ,1978. 359 RG. 9 LANDSAT Photograph, 30 Jan. , 1974. ■»\j ■■ ■ 4 i I I / > ■* > * 4 i - :,„'*:«-*-*-♦- "+ "* 5* ■» ^ ^ * !, J, J, ■.III T *„* If. T I. J J *\ )» * •> ^» n v 4 . $ V, y <» >, *, V . V i *, V J, I-./ J, 4 V V *. 4 ^ i ATCHAFALAYA to VERMILLION BAY Currents (cm/sec) Falling Tide Wind 15kn/30deg Lower Atchafalaya River , ,'rf <- *^ "N »N "^ 4 4 ' *■.'«,< . *, v *^ ^ J. i »-,*-i*-,'*>*-l*v« ' L •* r* ' . " e ip <+ ..« "< ' *■ ?-,*-,*- ' - - *-,.*-.?~,3s- u«-1(«- :• 'i-'V* f-.f-i*-!?-!? • < « -^ «»,.*«,«•,*■ -• f - • ,*-.- ' ". *- *»,>,: " • ' • 1 ■ 1 , ........... , , t ^ T 'r f T ■• • fj T f f f f T 1 t T FIG. 10 Current vector plot: Hart 2-dimensional mathematical model. 360 tidal conditions occurring at the time of the satellite pass (Figure 10). Since the estuary is shallow and well mixed, patterns which appear at the surface on Landsat were con- sidered to be representative of the water column in the bays. Offshore, the high sediment concentrations and sharp interface between the sediment plume and the more saline gulf water are thought to indicate strong mass density differences and a zone of f locculation. The results of the remote sens- ing model study indicate a more pro- nounced impact to the west, due in part to the predominance of south- easterly winds in the spring during the peak discharge period. Compli- menting tidal currents carry large volumes of sediment into the bays west of Atchafalaya Bay, as evidenced by a thick accumulation of sediments recently sampled in Vermilion Bay (Van Beek 1977) . Mud flat accretion has been detected as far west as the Texas coast, carried by the prevail- ing westerly littoral drift. An extensive prototype data- collection program, to provide data for a study of system hydrodynamics, sediment transport and delta growth trends, is currently underway in the estuary and near offshore areas. LSU-Sea Grant and Waterways Experi- ment Station are working coopera- tively, as well as independently, on this extensive modeling effort. PROSPECTS FOR THE REGION Projections of delta growth made by the Corps of Engineers indicate that the bay will be essentially filled by subaerial delta deposits by the year 2000, extending well off- shore by the year 2020 (USCOE 1974). LSU studies indicate a slightly more conservative estimate of bay filling in light of recent evidence of bay scour on the delta flanks and the sporadic flood-related nature of delta growth (Roberts et al. 1980). Projections of delta growth are made somewhat easier since the Atcha- falaya Delta is evolving in a similar manner as those described for sub- deltas of the modern Mississippi Riv- er and other shallow water deltas (Figure 11). Presently the mass and aerial extent of the Atchafalaya Delta are comparable to that of the Mississippi River's Baptiste Collette sub-delta, which started its building phase in 1874. Deltas of the Colo- rado, Trinity and Guadalupe Rivers in Texas, which are growing into shallow bays behind barrier islands, are also somewhat analogous to the Atchafalaya setting. However, several dilemmas are being posed by the growth of the At- chafalaya Delta which may bring about an alteration of natural delta growth patterns. Fisheries in the region have been severely impacted by ex- cess fresh water and sediment loads. There has been a decline in shrimp and fish catches, and a near collapse of the oyster industry in the area (Van Beek 1977). The State of Louis- iana discarded a sediment barrier plan, designed to ease these impacts in the bays to the west of Atcha- falaya Bay, as ineffective. There are equally pressing pro- blems faced by flood control and navigation interests. Morgan City, for example, is severely threatened with flood problems created by rising flowlines resulting from delta growth. Navigation interests are plagued with shoaling problems and, at the same time, are requiring deeper draft 361 0 4 6 Stat. mi. 0 2 4 6 8 10 Km. BAPTISTE COLLETTE CREVASSE TRINITY DELTA ATCHAFALAYA DELTA GUADALUPE DELTA COLORADO (f DELTA MATAGORDA FIG. 1 1 Comparison of size and shape of Atchafalaya delta with crevasse-splay deposit of modern Mississippi River and other smal modern deltas from coast of Texas. 362 navigation to support the booming oil industry. Levee and channel exten- sions are planned to alleviate these problems, but negative impacts as- sociated with salinity intrusion and marsh deterioration are feared if the projects are built. Other alternatives under con- sideration to aid these interests involve changes in distribution of flow between Wax Lake Outlet and the lower Atchafalaya River. Wax Lake Outlet is experiencing rapidly in- creasing flows at the expense of the lower Atchafalaya River because of its shorter route to the gulf. This is causing increased shoaling near Morgan City and loss of channel cross-sectional area for flood con- veyance past Morgan City. Among the proposals under con- sideration by the Corps of Engineers to alleviate this problem is a plan to construct a weir or overbank struc- ture above Wax Lake Outlet. This structure would restrict the passage of normal flows while allowing high flows over the weir during flood events. The project would increase normal flows past Morgan City, en- couraging natural channel scour, and hopefully result in an improved flood conveyance and improved navigation. A citizens group from Morgan City has proposed a complete closure of the Lower Atchafalaya River above Morgan City, with 100 percent of the flow exiting at Wax Lake Outlet. While this plan would afford flood protection, the cost, coupled with negative environmental impacts, makes it infeasible. None of these proposals will substantially alter long-term delta- building processes in the region; they will merely change the focal point of the impact. Regardless of the approach, there are urgent overall needs for Louisiana to capitalize on these deltaic processes. Numerous studies have shown that a renewed cycle of delta growth is essential for the replacement of lost land and the maintenance of environ- mental productivity in the coastal zone as a whole. The regenerative effects of deltaic sedimentation are particularly necessary for the long- term health of Louisiana's seafood industry. The economic hardships for fishing and navigation interests in the Atchafalaya-Vermilion area can be eased, but not prevented. Perhaps the addition of new land will stim- ulate economic alternatives for this region, similar to the development between New Orleans and Venice, Louisiana . Habitats and fishing grounds can shift in location and character in response to these deltaic processes. Unfortunately, people cannot. Econo- mics dictate the maintenance of the status quo in a highly dynamic geo- logic situation. The greater the superimposition of people and their settlements in a rapidly changing area like the Atchafalaya-Vermilion region, the more complex the prob- lems, and the more difficult the solutions . SUMMARY AND CONCLUSIONS The study of the subaerial growth and regional impacts of the Atchafalaya Delta have led to the following conclusions: 1. The subaerial phase of delta development started significantly after the flood of 1973, with abrupt increases in growth occurring follow- ing major flood events. 363 2. Vegetation progradation oc- curs most rapidly during the years following major floods, with little expansion noted during subsequent low water years due to erosional proces- ses . 3. Sediment-laden discharge impacts surrounding bays, marshes and near offshore areas, with the most significant impacts occurring west- ward due to the combined impact of wind, tidal currents and littoral drift. 4. Delta growth may be substan- tially altered by man in order to mitigate the impacts of delta growth processes upon fisheries, navigation and flood control interests. iana Academy of Sciences. 16:71- 84; 1978. Roberts, H. H., Adams, R. D., Cun- ningham, R. H. Evolution of sand-dominant subaerial phase, Atchafalaya Delta, Louisiana. Amer. Assoc. Petroleum Geolo- gists Bull. 64:264-279; 1980. Rouse, L. J. , Roberts, H. H. , Cun- ningham, R. H. W. Satellite ob- servations and subaerial growth of the Atchafalaya delta, Louis- iana. Geology 6: 405-408; 1978. Sasser, C. E. LSU-Sea Grant sponsored research, unpublished. LITERATURE CITED Fisk, H. N. Geological investiga- tions of the Atchafalaya basin and the problem of the Missis- sippi River diversion: U.S. Army Corps of Engr. , Miss. River Comm. , Vicksburg, Miss. l:145p; 1952. Frazier, D.E. Recent deltaic deposits of the Mississippi River: their development and chronology. Gulf Coast Association Geological Society 1967; 287-311. Kolb, C. R., Van Lopik, J. R. De- positional environments of the Mississippi River deltaic plain. Deltas in their geologic frame- work: 1966: 17-61. Available from Houston Geological Society. Montz, G.N. Vegetational character- istics of the Atchafalaya River Delta. Proceedings of the Louis- Shlemon, R. J. Subaqueous delta for- mation - Atchafalaya Bay, Louis- iana. Deltas: 1975: 209-221; Available from Houston Geologi- cal Society . U.S. Army Corps of Engineers (USCOE) . Preliminary draft environmental impact statement, Atchafalaya Basin floodway. New Orleans District; 1974. Van Beek, J. L. A jetty from Pt. Chevreuil: an evaluation of a proposal to reduce sedimentation in the Cote Blanche and Vermil- ion Bays. Coastal Environments Inc. for Louisiana State Plan- ning Office; 1977: 59p. Van Heerden, I. H. Sedimentary re- sponses during flood and non- flood conditions, Atchafalaya delta, Louisiana. Baton Rouge: Louisiana State University; 1980. 150 p. Master's Thesis. 364 DISCUSSION Question: You stated that your measurements show that about 50 per- cent of the sediment delivered to Atchafalaya Bay vicinity is being re- tained in delta building and related processes, and that another 50 per- cent is escaping. Is that basically correct? Answer: The only thing we have to base that estimate on are some hydro surveys done in the bay and some cross-sectional sediment range measurements taken inside the basin from which we computed sediment bud- gets for the Atchafalaya Basin. What leaves the system was determined by looking at sequential hydrographic surveys. Looking at one in 1967, one in 1972, and one in 1977, we have tried to quantify the amount of de- position in the bay. And then we just simply subtract the amount of deposition from what was coming into the system and, from that, we deter- mined that less than 50 percent of the material is being retained in the bay. But that's not exactly the whole story because the type of mate- rial that is being retained in the bay is the coarse-grained material or the sandy material, whereas the fine silts and the clay particles as seen on the landsat imagery, are easily escaping the bay with tidal processes. It's a complex problem. Question: I have a second part to my question. My name is Sherwood Gagliano. Is the escape of this other 50 percent or less due largely to the maintenance of the navigation channel through the Achafalaya, and, if so, has the sediment transport in that channel been measured? Answer: We're currently in a cooperative program with USGS mea- suring some of the major distributa- ries in the delta. However, it's al- most impossible, as your group has found, to measure out around Eugene Island at the break in the reef, where the navigational channel cuts through, to determine just how much is escaping by that route. But I understand in talking to Johannas that your measurements indicate that perhaps as much as 20 percent is es- caping at least below the subaerial portion of the delta. Whether or not it's going into the bay or the reef, no one knows. There is some indica- tion from our studies that there is a good possibility of a marine delta forming seaward of the shell reef. We have some side scan sonar data and sediment data and there's been some sand sampled out there. It could be that the dredging of the navigation channel and the confinement of flow is carrying some of the sediment out beyond the reef. But you know, this is all kind of speculation right now. We haven't really confirmed that. We're working on that problem right now. Speaker: John Weber "Planning Prob- lems Associated with Freshwater In- troduction into Louisiana Coastal Areas" Question: (Dan Taylor, Fish and Wildlife Service). Have your studies progressed far enough to determine what you will tie the fish and wild- life benefits to. That is, what phy- sical parameters, like the movement of isohalines, or reduction in marsh deterioration, and, if so, what do you plan to tie those benefits to? Answer: I'd like to pass that question on to the next speaker. He's more familiar--are you talking about the Mississippi-Louisiana Estuarine Study, or both of them? 365 FRESHWATER INTRODUCTION INTO LOUISIANA COASTAL AREAS John C. Weber and Robert A. Buisson, Jr. Department of the Army, New Orleans Distict Corps of Engineers, New Orleans, Louisiana ABSTRACT AREA DESCRIPTION AND BACKGROUND INFORMATION The conservation and enhance- ment of fish and wildlife resources through the control of salinities in portions of the estuarine area of Louisiana are the purposes of one authorized project and two ongoing studies in the U.S. Army Engineering District, New Orleans. The primary measure identified for controlling salinities is to divert water from the Mississippi River near the delta to adjacent estuarine areas. Plan- ning and implementing this type of project presents a challenge from both technical and institutional standpoints. Technically, the state-of-the-art for quantifying benefits and impacts must rely on expert judgment and assumptions. From the institutional aspect, freshwater diversion is supported by many Federal, State, and local agencies and organizations. However, obtaining local cooperation and sup- port for specific diversion sites may be the most difficult problem to solve because the local areas where diversion facilities would be located are not necessarily the areas receiving significant benefits from diversion. In some areas, benefits may not outweigh adverse impacts involved with constructing and operating diversion facilities. For the most part, benefits would be widespread and would accrue to interests not directly participating in the project. The State of Louisiana contains one of the Nation's most productive estuarine areas. The area consists of 363 miles of shoreline directly fronting waters of the open Gulf of Mexico (Becker 1972) and is pre- dominantly composed of 4.2 million acres of estuarine marsh lying at or near National Geodetic Vertical Datum (NGVD) (U.S. Army Corps of Engineers 1970). Pocked with numerous shallow lakes and bays and interlaced with a complex network of channels and ca- nals, both natural and manmade, this mixing zone represents a resource of great value to the State and Nation. It is estimated that there are nearly 30,200 total miles of shoreline in the area, including the tidal shore- lines of bayous, rivers, marsh lakes, islands, and canals (Becker 1972). The salinities of the waters in the lakes, bays, and channels vary from near zero to over 28 parts per thou- sand, depending upon location and numerous climatological , meteorologi- cal, and hydrological factors. A unique feature of the estu- arine area is its interrelationship with the Nation's largest river, the Mississippi. The average flow of the Mississippi River into the area is about 450,000 cubic feet per second (U.S. Army Corps of Engineers 1970). Below Old River, the Mississippi transports some 300,000,000 tons of 366 sediment in an average year (U.S. Army Corps of Engineers 1970). Most of the present estuarine-marsh com- plex owes its existence to the delta- building process of the Mississippi River. Historically, the Mississippi River annually overflowed the vast marshlands and estuaries, depositing sediments throughout the flood plain and also in the shallow waters of the Gulf of Mexico, over the continental shelf. The sedimentation from these yearly floods generally exceeded in total effect the attritional pro- cesses of erosion, compaction, and subsidence, so that the shoreline ad- vanced seaward (U.S. Army Corps of Engineers 1970) . Investigations have disclosed that continuing change is taking place in nearly all of the important physical and chemical parameters from which the area derives its unique character. Further, it has become apparent that these changes relate, in the long-term sense, pri- marily to the alteration of the over- flow regimen of the Mississippi Riv- er. In the past 250 years, man has increasingly restricted the river overflow into the estuarine zone in Louisiana through the construction of works to control devastating floods and to provide for dependable naviga- tion. Deprived of the overflow, with its nourishing sediments, the area is yielding to the sea through subsi- dence and erosion. Another important source of change in Louisiana's estu- arine area is the development of the area for various economic pursuits, particularly those associated with the fisheries and petroleum indus- tries. The construction of new wa- terways to service these industries has had a profound effect on salini- ties and flow patterns in the area (U.S. Army Corps of Engineers 1970). ESTUARINE AREA STUDIES A number of agencies at the Federal, State, and local level have recognized the changing conditions of the Louisiana estuarine environment. As a result, Congress has directed the U.S. Army Corps of Engineers to undertake certain investigations to determine the feasibility of provid- ing water resource improvements in the interest of conservation and en- hancement of fish and wildlife re- sources. The U.S. Army Engineer Dis- trict, New Orleans, has conducted several investigations involving di- version of freshwater from the Mis- sissippi River to portions of the estuarine area. The earliest study, conducted in the late 1950' s, re- sulted in the congressional authori- zation of the Mississippi Delta Re- gion Salinity Control project. The project, which is depicted in Figure 1, was authorized by the Flood Con- trol Act of 1965 as part of the Com- prehensive Plan for Modification of Flood Control and Improvement of the Lower Mississippi River (U.S. Army Corps of Engineers 1979). It con- sists of four gated-water or salin- ity-control structures on the banks of the Mississippi River with con- necting levees and channels that will introduce fresh water from the Mis- sissippi River to the bays and marshes of the Mississippi Delta. Salinity-control structures would be located on the east bank of the river at Bohemia and Scarsdale and on the west bank at Myrtle Grove and Home- place. The objective of the project is to increase wetlands productivity by the establishment of an ecological regimen favorable to the production of oysters, shrimp, fish, furbearing animals, and migratory waterfowl. The current estimated cost of the project is $30,000,000, of which $22,500,000 367 u u v si (A OJ Ul 3 370 0 k k o m k S-l < 3 CI ■H U 3 j-> CO W nj C ct) •^ co ■H 3 O c "5 ■H Cm Ck •H co co •H CO CO 3 371 Poydras, Louisiana, and openings of the Bonnet Carre Spillway in 1950, 1973, 1975, and 1979. The spillway is a feature of the Mississippi River and tributaries project, lo- cated about 33 miles above New Orleans. It is designed to introduce floodwaters from the Mississippi River to Lake Ponchartrain to prevent overtopping of levees at and below New Orleans. Data on these flood control diversions indicate that after a short-term adverse impact, dramatic increases in fish and wild- life populations have been experi- enced for the next several years. Considering the limited information on actual experiences, the technical studies will necessarily be mostly theoretical . Of the technical studies that must be conducted, the ecological studies play a crucial role and form a base for the engineering and economic studies. The ecological studies must quantify the physical and chemical changes desired in the environment to produce optimal con- ditions for fish and wildlife re- sources. However, because of the presently imprecise nature of the science, these analyses are diffi- cult to perform. Our current knowl- edge of relationships between changes in the physical and chemical parameters and biological communi- ties are based largely on inductive reasoning and expert judgment. Because the optimal conditions to be achieved by the diversions cannot be precisely defined, a logi- cal approach to the study is to stage development of the project. Under this approach, a diversion plan would be developed based on current ecological studies and other technical studies that are dependent on the ecological studies, all of which would be performed at the same level of detail. Studies for site evaluation, design, and cost estimates would be performed at a full level of detail. Prior to construction of the entire project, a pilot element would be constructed to provide sufficient data to re- evaluate and modify additional ele- ments of the plan, as necessary. Such an approach would also facili- tate resolution of institutional arrangements for specific sites and permit construction at the earliest practicable time. INSTITUTIONAL CONCERNS Developing institutional ar- rangements to divert Mississippi Riv- er flow to adjacent estuaries is a difficult task. Both political and social institutions play an essential role in the planning process and can be critical determinants of the im- plementability of a plan. The capa- bility and willingness of existing institutions to meet project require- ments in monetary, and nonmonetary terms is a necessary ingredient for eventual realization of a diversion plan. The institutions considered critical include, among others, State, parish (same as county), and municipal governments and agencies, tax structures, and general local and regional attitudes. Potential diver- sion sites along the Mississippi Riv- er are all located in the State of Louisiana in 10 parishes which have political jurisdiction over the lands adjacent to the river. In addition, numerous cities, towns, and communi- ties, including the city of New Or- leans, are located on the banks of the river in the area. A major complication with fresh- water diversion is that a project of the magnitude being considered would 372 have serious adverse as well as bene- ficial effects. The beneficial effects would be widespread in relation to the adverse effects, which would be concentrated at and near the diversion sites. The ad- verse effects can be separated into two distinct categories: those that would occur in the developed areas adjacent to the river, and those that would occur in the estuarine area at and in the vicinity of the freshwater introduction. The lat- ter type would be an adverse impact on the environment and fish and wildlife resources. The general configuration of the lower Mississippi River and the development of the area play a major role in the problem. The natural alluvial levees and ridges located beteeen the Mississippi River and uplands adjacent become highly developed as urban, industrial, and prime agricultural lands. These developed lands have been protected from Mississippi River floods and, in most cases, from tidal flooding from the direction of the estuaries. Any diverted river flow must be routed through these developed lands, which would cause problems in these areas. Each diversion site would require at least structures in the Mississippi River levee to insure continued flood protection, and at many possible sites, additional structures would be required in levees bordering the estuaries. For diversions of the magnitude con- sidered essential to affect major portions of the estuaries, channels are required to convey the flow. These channels would require lands, relocations of residential and com- mercial structures , and modifica- tions to intercepted drainage sys- tems, roads, streets, railroad tracks, pipelines, and utilities. The detrimental effects on the estuaries could include localized short-term impacts in the vicinity of the freshwater introduction and long-term impacts that would encom- pass a much larger area. Antici- pated adverse impacts consist of the following: high levels of coliform bacteria, heavy metals, pesticides, phenols, and PCBs ; too fresh an area for oysters and other sessile organ- isms to survive; temperature differ- ences (river water is cooler) ; and increased turbidity. The magnitude and extent of the areas adversely affected would vary depending on the location of diversions. However, the percentage of the area adversely affected would probably be small compared to the area benefited. Downriver sites are the most effec- tive, but the estuarine areas that would be adversely affected are among the most productive and are heavily fished. Another factor that will influ- ence local institutions is the con- tribution that fish and wildlife re- sources make to the local economies. Generally, the importance of fish and wildlife to the local economies in- creases progressively from upriver to downriver. Therefore, the situation occurs that where fish and wildlife are not economically important, the adverse impacts and commitments ne- cessary are not offset by the bene- fits to the local area. At downriver sites, fish and wildlife may be im- portant from an economic viewpoint, but because the detrimental effects in both the developed and estuarine areas are not offset by the benefits in the local area, local interests do not usually find such a plan acceptable. This latter situation is one of the reasons why the authorized Mississippi Delta Region has not been implemented. 373 There is no doubt that the benefits from a diversion project would be regional in nature and accrue to local and regional interests that are not directly participating in the project. For this reason, the concept of river water diversion is broadly supported; however, the institutional diffi- culties at the local level have not yet been resolved. The most common- ly suggested approach to resolution of the problem is for all interests that will benefit from the project to organize and provide some sort of recompense to those that would be adversely affected. This sort of solution could be accomplished in a number of ways. Currently, alterna- tives for minimizing the adverse impacts are being fully explored. SUMMARY Many problems and difficulties must be overcome to achieve effectual salinity alterations in the Louisiana coastal zone. Because of the diffi- culties in projecting finite impacts and benefits, a pilot project should be constructed which would afford opportunity to collect and evaluate extensive biological and water quality data. The analysis of these data would provide a means to modify additional elements of the overall plan. An aggressive approach must be implemented to educate local interests of the merits of freshwater diversion and overcome institutional problems . LITERATURE CITED Coastal Louisiana. Report No. 15. Baton Rouge, LA: Coastal Resources Unit, Center for Wet- land Resources, Louisiana State University; 1972. U.S. Army Corps of Engineers, New Orleans District. Report on Mississippi River flow require- ments for estuarine use in coastal Louisiana. Fish and Wildlife Study of the Louisiana Coast and the Atchafalaya Basin; 1970; 28p. U.S. Army Corps of Engineers, New Orleans District. Plan of Sur- vey, Louisiana Coastal Area; 1975; 58p. U.S. Army Corps of Engineers, Lower Mississippi Valley Division, Water Resources Development by the U.S. Army Corps of Engineers in Louisiana; 1979; 205p. DISCUSSION Question: Dan Tabberer Fish and Wildlife Service. Have your studies progressed far enough to determine what you will tie the fish and wild- life benefits to, that is, what physical parameters, like movement of isohalines or reduction in marsh deterioration, and, if so, what do you plan to tie those benefits to? Answer: I'd like to pass that question on to the next speaker, he's more familiar with them. Are you talking about the Mississippi- Louisiana Estaurine Study, or both of them? Becker, R. E. Measurement of coastal Louisiana's shoreline. Hydro- logic and Geologic Studies of Question: Either one. Answer: I guess a fair answer to your question, Dan, is that I don't know if we've progressed to 374 that point, but I don't see where it makes that much difference which parameters we tie them to as long as we can document the benefits asso- ciated with that diversion. And, as I mentioned to you earlier this morn- ing, we can recommend to Congress a program that has a B.C. (benefit/ cost) ratio of less than one if it is an environmental enhancement project. The district engineer views fresh- water diversion in that manner and he would have no problem at all rec- ommending to higher authority that the project be authorized even though we are having problems coming up with monetary values for benefits. Question: Just what is your anticipated schedule for implementa- tion of the first structure? Answer: That is somewhat in the state of flux, because the Louisiana Coastal area study is a long-term study so what we have to do with that one is to get authorization to go with an interim report to address just freshwater diversion instead of erosion prevention and hurricane protection and other things we're supposed to study. The request to do that is now in Washington and we're waiting for approval. And as far as the Mississippi-Louisiana estuarine study, we're attempting to accelerate that schedule and combine the state two and three phases of the study which will shorten the period of time for it. But we do not have authorization to do that at the present time, that's the best answer I can give you. 375 BIOLOGICAL CONSIDERATIONS RELATED TO FRESHWATER INTRODUCTION IN COASTAL LOUISIANA Dennis L. Chew and Frank J. Cali U.S. Army Corps of Engineers New Orleans, LA 70160 ABSTRACT Louisiana has experienced a rapid loss of coastal wetlands due to natural processes such as subsid- ence and erosion, as well as man's engineering activities including leveeing, channelization and pe- troleum exploration. These activi- ties have led to a reduction in overbank flooding and natural dis- tributary flow which historically provided fresh water, sediments and nutrients to estuarine areas. In addition, construction of large navigation channels has caused pro- gressive intrusion of saline waters. This has resulted in conversion of fresh, intermediate and brackish marshes to intermediate, brackish and saline marshes, respectively, as well as loss of some areas of wooded swamp. Saltwater intrusion and loss of wetlands have adversely affected productivity of wildlife and fishery resources and have led to declines in populations of waterfowl, fur- bearers and important shellfish and finfish species. Influx of saline waters is particularly harmful to the American oyster, due to in- creased predation. Juvenile stages of shrimp, menhaden and blue crabs are estuarine-dependent and utilize nearshore estuaries and adjacent wet- lands as nursery areas. One way to ameliorate loss of wetland nursery areas and rate of saltwater intru- sion is timely introduction of fresh water to provide sediments and nutrients vital to coastal wetlands. Major constraints to freshwater in- troduction in Louisiana are poor water quality and lower temperatures in the Mississippi River as compared to adjacent estuaries. INTRODUCTION Louisiana is experiencing a rapid loss of wetlands, including bottomland hardwood forests, wooded swamps and coastal marshes. Gagliano and van Beek (1970) reported that coastal Louisiana is experiencing a net land loss in excess of 16.5 square miles per year. These land losses have occurred as a result of natural processes, as well as man's engineering activities. Natural processes of subsidence, compaction and erosion have converted large areas of coastal marshes to open water (Morgan 1973). Construction of major naviga- tion channels and oil exploration canals have also been responsible for loss of large areas of wetland habitat. An example is the Mississippi River-Gulf Outlet, a 78-mile-long channel which runs from New Orleans to the Gulf of Mexico. Channel excavation, dredged material 376 disposal and bank erosion associated with this channel have caused the direct loss of over 24,000 acres of forested wetlands, coastal marsh and associated shallow estuarine waters (U.S. Fish and Wildlife Service 1980). Leveeing of the Mississippi River has disrupted historical pro- cesses of overbank flooding and dis- tributary flow, thereby depriving coastal marshes of fresh water, nutrients and sediments. Reduced freshwater inflows, in combination with navigation channels, have resulted in saltwater intrusion and a reduction in quality of existing marsh habitat. Serious declines in swamp and marsh habitat have resulted in severe impacts on fish and wildlife resources and it is anticipated that these losses will continue in the future. Reduction in habitat has led to decreases in populations of wildlife, including resident and migratory waterfowl, wading birds, shorebirds, furbearers and a variety of small and big game animals. These losses have led to decreases in com- mercial fur harvest and reduced op- portunities for activities such as waterfowl, big game and small game hunting. Saltwater intrusion has caused drastic changes in plant and animal communities. Fresh-intermediate marshes have been converted to more saline types and some areas of wood- ed swamp have been entirely elimi- nated. These changes in habitat types have seriously altered the structure of wildlife communities. Conversion of fresh-intermediate marshes to more saline types has re- sulted in elimination of valuable wa- terfowl habitat and has also reduced populations of important furbearers such as muskrat (Ondatra zibethica) and nutria (Myocastor coypus) . Loss of coastal marshes has also adversely impacted the produc- tion of fish and shellfish species. In coastal Louisiana, the majority of commercially important fish and shellfish species are estuarine- dependent, with juveniles utilizing the estuaries as nursery areas. Marshes provide a source of organic detritus, a vital component of the estuarine food web; the importance of marsh vegetation as a source of organic detritus has been well docu- mented (Darnell 1961, Odum et al. 1973). Increases in salinity levels in Louisiana estuaries have reduced availability of low salinity nursery habitat important to penaeid shrimp (Penaeus spp.), blue crabs (Cal- linectes sapidus) , Atlantic croakers (Micropogon undulatus) and menhaden (Brevoortia spp.). Saltwater intru- sion has also eliminated habit.it important to the American oyster (Crassostrea virginica). Salinities exceeding 12-15 ppt permit the south- ern oyster drill (Thais haemostoma) and other oyster predators to move in over oyster reefs. In addition, saltwater intrusion has caused areas suitable for oyster cultivation to shift inland and closer to sources of pollution. This has led to more frequent oyster reef closures by public health officials. In order to ameliorate these problems, the New Orleans District of the U.S. Army Corps of Engineers has undertaken studies to investi- gate the diversion of fresh water from the Mississippi River to coast- al areas of Louisiana. Two promi- nent studies being undertaken are entitled "Mississippi -Louisiana Estuarine Areas Study" (MLEA) and the "Louisiana Coastal Area Study" (LCA). The MLEA study area is lo- cated in southeastern Louisiana, 377 southern Mississippi, and south- western Alabama. The 4,700-square mile area extends from Dauphin Island, Alabama, on the eastern end of Mississippi Sound, to the east bank of the Mississippi River be- tween Bayous Manchac and Terre Aux Boeufs in southeastern Louisiana. The LCA study area encompasses that part of the Mississippi River Deltaic Plain located in southern Louisiana, exclusive of the active Mississippi Delta, extending from the Atchafalaya River on the west to Breton Sound on the east. A map of the two study areas may be seen in Figure 1. STUDY OBJECTIVES AND IMPACTS OF FRESHWATER DIVERSION MEASURES Planning objectives to be satisfied by freshwater diversion measures include creation and resto- ration of coastal wetlands, enhance- ment of vegetative growth, creation of favorable salinity gradients (5-15 ppt) and increases in productivity of fish and wildlife resources. BENEFICIAL IMPACTS FISHERY RESOURCES Fishery resources will be bene- fitted by reduction in saltwater in- trusion which will increase availa- bility of nursery habitat with favorable salinity regimes. Sediment and nutrient input resulting from freshwater diversion will serve to decrease marsh loss and enhance vegetation growth. Increases in nutrient input will also increase production of phytoplankton and zoo- plankton populations, which are highly important in the estuarine food web. Increases in acreage of marsh and vegetative biomass will benefit fisheries production by in- creasing production of organic detri- tus. The majority of finfish and shellfish species of commercial and recreational importance are estu- arine-dependent , utilizing inshore estuaries as nursery areas. Juve- niles of estuarine-dependent species move into estuarine nursery areas, and taking advantage of low salini- ties, elevated water temperatures and abundant food, grow very rapidly dur- ing the warm spring and summer months. The value of shallow marsh nursery areas for estuarine-dependent species has been well documented. Studies by Rogers (1979) and Simo- neaux (1979) in the Upper Barataria Basin have shown such areas to be of value to juvenile Atlantic croaker and menhaden, respectively. White and Boudreaux (1977) conducted stud- ies which demonstrate the importance of shallow marsh areas in Louisiana for brown shrimp (Penaeus aztecus) and white shrimp (Penaeus setiferus) . Turner (1979) reported that inshore shrimp catches in Louisiana are di- rectly proportional to the area of intertidal wetlands and not related to mere areal extent of estuarine waters. More (1969) documented the value of marsh habitat for blue crabs. Studies in Texas have shown the value of shallow marsh waters as habitat for immature sand seatrout (Cynoscion arenarius) and southern flounder (Paralichthys lethostigma) (Conner and Truesdale 1973). The value of freshwater inflow has been historically demonstrated. Viosca (1938) reported the 1937 open- ing of the Bonnet Carre' Spillway re- sulted in beneficial effects on oysters, saltwater finfishes and penaeid shrimp. Gunter (1950) re- ported the 1945 and 1950 openings 378 rvKX! • 1 z o to LU ,£ o bj q: o: / °- a 3 > T3 3 +J CO ■-1 a 4-> Oi •H •H r- 1 T> 4-1 01 01 d TO CJ T3 3 i— 1 CU 3 O O U TO XI CO > u CJ o &« "—l TO E c TO "O 0) c a TO 1-1 > •H PS T3 3 TO c T3 3 TO 01 01 VI 01 3 O •H 4-1 TO •H •1-1 TO 0) Oh 4J On S-i 1— 1 TO Oh 4-> o S-l i— 1 ■H S-l 00 d O 01 TO •r-l 01 •r-l 01 XI OS 4-1 > •H CJ c 0] 4-> 0) 0) s~s oi a x: a •H o H a Cl, 4-4 3 * 01 TO cu oi 0) XI 01 XI 0) c u a 4-1 TO oo S-l c • >-3 o •H >> 03 T3 W =! 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Cooler temperature of diverted fresh waters, as well as synergistic effects of temperature and salinity, could adversely affect growth and survival of these populations. Venkataramaiah et al. (1974) con- ducted a series of laboratory experi- ments with brown shrimp which clearly demonstrated effects of interaction between salinity and temperature. Barrett and Gillespie (1973) reported that the total number of hours of wa- ter temperature below 20°C after the first week in April appeared to be a critical factor influencing brown shrimp production in Louisiana. Ju- venile brown shrimp survive and grow best at salinities ranging from 15-20 ppt; discharge of cooler river waters during periods of rising salinities and temperatures could lower tempera- tures and salinities enough to sig- nificantly reduce production of brown shrimp. Oysters can also be ad- versely affected by synergistic ef- fects of salinity and temperature. Salinities below 5 ppt when tempera- tures are below 20°C do not signifi- cantly harm oysters. However, pro- longed periods of salinities less than 5 ppt when temperatures exceed 20°C can lead to high mortalities (Lindall et al. 1972). WILDLIFE RESOURCES Primary adverse impacts on wildlife resources would result from excavation and dredged material dis- posal due to construction of diver- sion channels. It is estimated that a typical diversion channel would require a right-of-way approximately 500 feet wide for the channel itself, berms, levees and disposal area. Habitat types which would be impact- ed include bottomland hardwood for- ests, wooded swamps and marshes. Diversion routes under investigation under the MLEA and LCA studies range in length from 4 to 65 miles. CONCLUSIONS It is acknowledged that the concept of freshwater diversion is not without problems; however, cer- tain measures could be taken to lessen the severity of some of the negative impacts. Adverse impacts on fisheries resources could be minimized by careful planning of the design and operation of diversion structures. If possible, water should be diverted at a site in the river where pollution is minimal; however, this may not be feasible from an engineering standpoint. Benefits would be optimized by di- verting water in late winter and early spring before the majority of juvenile organisms have moved into nursery areas. Also, diversion structures should be located far enough from receiving water to allow solar heating of diverted water. Maximum heating could be obtained by allowing overland flow through marshes. This would have the addi- tional benefit of stabilizing nutrient concentrations and reducing levels of toxic substances. In- tensive water quality monitoring of released water and receiving water would be necessary through at least two growing seasons. If high pol- lution levels are observed in the river, control structures could be closed until water quality improved. Animal and plant tissues should be analyzed to determine the degree of bioaccumulation of toxic substances. It is evident that coastal Louisiana is experiencing severe problems resulting from loss of 383 coastal wetlands and saltwater in- trusion, and that freshwater diver- sion is one of the primary measures which could be used to alleviate these problems . Positive and nega- tive aspects of the measure must be carefully weighed. At the present time, it is the general consensus of the agencies responsible for regulation and management of fish and wildlife resources in coastal Louisiana, as well as the public, that overall benefits would out- weigh negative impacts. ACKNOWLEDGEMENTS Rouge, LA: Louisiana State University; 1973; 259-276. Darnell, R. M. Trophic spectrum of an estuarine community based on studies of Lake Ponchartrain, Louisiana. Ecology 42: 553- 568; 1961. Dugas , R. J. Oyster distribution and density on the productive portion of state seed grounds in southeastern Louisiana. Louisiana Department of Wild- life and Fisheries, Seafood Division, Technical Bulletin 23; 1977; 27p. This paper is based in part on information contained in Planning Aid Reports on the Mississippi and Louisiana Estuarine Areas Study and the Louisiana Coastal Area Study. The reports were prepared by David W. Fruge and Richard Ruelle, U.S. Fish and Wildlife Service, Division of Ecological Services, Lafayette, Louisiana, for the U.S. Army Corps of Engineers, New Orleans Dictrict. LITERATURE CITED Barrett, B. B. ; Gillespie, M.C. Primary factors which influence commercial shrimp production in coastal Louisiana. Louisiana Wildlife and Fisheries Commis- sion. Oysters, Water Bottoms, and Seafoods Division, Techni- cal Bulletin 9; 1973; 28p. Conner, J.V.; Truesdale, F. M. Ecol- ogical implications of a freshwater impoundment in a low-salinity marsh. Chabreck, R.H., ed . Proceedings of the Coastal Marsh and Estuary Management Symposium. Baton Gagliano, S.M.; van Beek, J.L. Geo- logic and geomorphic aspects of deltaic processes, Missis- sippi delta system. Hydrologic and geologic studies of coast- al Louisiana. Baton Rouge: Coastal Studies Institute and Department of Marine Sciences, Louisiana State University 1: 1-140; 1970. Gunter, G. The relationship of the Bonnet Carre Spillway to oyster beds in Mississippi Sound and the "Louisiana Marsh," with a report on the 1950 opening. Publications of the Institute of Marine Science, University of Texas 3: 17-77; 1950. Ho, C.L.; Barrett, B.B. Distribu- tion of nutrients in Louis- iana's coastal waters in- fluenced by the Mississippi River. Louisiana Wildlife and Fisheries Commission, Oysters, Water Bottoms and Seafoods Division, Technical Bulletin 17; 1975; 39p. Lindall, W.N., Jr.; Hall, J.R.; Sykes, J.E.; Arnold, E.L., Jr. 384 Louisiana coastal zone: analyses of resources and resources de- velopment needs in connection with estuarine ecology. Sections 10 and 13 -- fishery resources and their needs. Prepared by National Marine Fisheries Ser- vice Biological Laboratory, St. Petersburg Beach, Florida, for Department of the Army, New Orleans District, Corps of Engineers, Contract No. 14-17- 002-430; 1972; 323p . More, W.R. A contribution to the biology of the blue crab (Callinectes sapidus Rathbun) in Texas, with a description of the fishery. Texas Parks and Wildlife Department, Technical Series No. 1; 1969; 31p. Morgan, J. P. Impact of subsidence and erosion on Louisiana coast- al marshes and estuaries. Chabreck, R.H. , ed. Proceed- ings of the Coastal Marsh and Estuary Management Symposium. Baton Rouge, LA: Louisiana State University; 1973; 217- 233. Simoneaux, L.F. The distribution of menhaden, genus Brevoortia, with respect to salinity, in the up- per drainage basin of Barataria Bay, Louisiana, Baton Rouge, LA: Louisiana State University; 1979; 96p. M.S. Thesis. Turner, R. E. Louisiana's coastal fisheries and changing environ- mental conditions. Day, J.W. , Jr.; Culley, D.P., Jr.; Turner, R.E.; Mumphrey, A.J. , Jr., eds . Proceedings of the Third Coast- al Marsh and Estuary Management symposium. Baton Rouge, LA: Louisiana State University; 1979; 363-370. U.S. Fish and Wildlife Service. A planning aid report on the Mis- sissippi and Louisiana estu- arine areas study. Prepared by the U.S. Fish and Wildlife Service Division of Ecological Services, Lafayette, Louisiana, for the U.S. Army Corps of Engi- neers, New Orleans District; 1980; 86p. Odum, W.E.; Zieman, J.C.; Heald, E. J. The importance of vascular plant detritus to estuaries. Chabreck, R.H., ed. Proceed- ings of the Coastal Marsh and Estuary Management Symposium. Baton Rouge, LA: Louisiana State University; 1973; 91-114. Rogers, B.D. The spatial and tempo- ral distribution of Atlantic croaker Micropogon undulatus , and spot, Leiostomus xanthurus , in the upper drainage basin of Barataria Bay, Louisiana. Baton Rouge, LA: Louisiana State Uni- versity; 1979; 96p. M.S. Thesis. Venkataramaiah, A.; Lakshmi, G. J. ; Gunter, G. Studies on the ef- fects of salinity and tempera- ture on the commercial shrimp. Penaeus aztecus Ives, with spe- cial regard to survival limits, growth, oxygen consumption, and ionic regulation. Prepared for U.S. Army Engineers Waterways Experiment Station, Vicksburg, Mississippi, Contract Report H-74-2; 1974; 134p. Viosca, P., Jr. Effect of the Bon- net Carre Spillway on fish- eries. Louisiana Conservation Review 6:51-53; 1938. 385 Wells, F. Hydrology and Water Qual- White, C. J.; Boudreaux, C.J. Dev- ity for the Lower Mississippi elopment of an areal management River. Prepared by United concept for gulf penaeid States Geological Survey for the shrimp. Louisiana Wildlife and Louisiana Department of Trans- Fisheries Commission, Oysters, portation and Development, Of- Water Bottoms, and Seafoods fice of Public Works, Technical Division, Technical Bulletin Report 21; 1980; 83p. 22; 1977; 77p. 386 EFFECTS OF WETLAND CHANGES ON THE FISH AND WILDLIFE RESOURCES OF COASTAL LOUISIANA David W. Fruge U.S. Fish and Wildlife Service Lafayette, LA ABSTRACT The vast wetlands of the Louisiana Coastal Region (LCR) are of national importance to fish and wildlife. These wetlands winter one-fourth of the North American dabbling duck population, a large portion of the Mississippi Flyway's diving ducks, and over 400,000 geese. Coastal Louisiana also sup- ports numerous other migratory birds, many of which nest in its wetlands. The LCR marshes produce the largest fur harvest in North America, and support the largest volume of estuarine-dependent fish and shelfish landings in the United States. Fish and wildlife-related recreation in the LCR is also ex- tensive, including 11.9 million man-days of saltwater fishing and crabbing in 1975 and 676,000 man- days of waterfowl hunting during the 1977-1978 season. Prior studies documented an annual land-loss rate of over 16.5 mi /yr (42.7 km yr) in the LCR. More recent investiga- tions indicate that this rate of wetland loss more than doubled since 1956. Wetland deterioration, which is partially attributable to natur- al causes, has been greatly accel- erated by human influences such as navigation channel excavation, agricultural drainage, and construc- tion of mainline Mississippi River levees that have prevented fresh- water and sediment overflow into adjacent subdelta marshes. Contin- ued wetland deterioration may lead to serious declines in estuarine- dependent fish and shellfish har- vest, fur catch, waterfowl habitat, and related fish and wildlife pro- ductivity. The U.S. Fish and Wild- life Service (USFWS) has long advocated freshwater diversion for habitat improvement in the Missis- sippi Deltaic Plain Region and is presently participating in the evaluation of several freshwater diversion sites being investigated by the U.S. Army Corps of Engineers. Preliminary USFWS estimates indi- cate that the monetary value of fish and wildlife productivity can be increased by more than $4.5 million/yr with a single large-scale freshwater diversion structure that would introduce Mississippi River water into the Lake Pontchartrain- Lake Borgne Basin of southeast Louisiana. Because federally fi- nanced public works projects have played a major role in wetland de- terioration in the LCR, mitigation of these losses through the federal public works program would seem appropriate. INTRODUCTION AREA SETTING The Louisiana Coastal Region (LCR) contains a vast expanse of 387 valuable wetlands. Chabreck (1972) estimated that this area contained approximately 2.5 million acres (1 million ha) of fresh to saline marsh, 1.8 million acres (0.7 mil- lion ha) of ponds and lakes, and over 125,000 acres (50,588 ha) of bayous and rivers in 1968. The LCR has been divided into two main physiographic units (Morgan 1973) : the Deltaic Plain of the central and eastern portions and the Chenier Plain of the western portion (Figure 1). Both of these regions have been developed over the past 5,000 years by a series of prograd- ing and overlapping deltaic lobes composed of sediments transported by the Lower Mississippi River and its distributaries (Morgan 1973). Both the Deltaic Plain and the Chenier Plain have been the subject of extensive ecological characteri- zation efforts by the U.S. Fish and Wildlife Service's National Coastal Ecosystems Team. Based on Chabreck (1972) and Gosselink et al. (1979), it is estimated that 74 percent of Louisiana's coastal marches occur in the Deltaic Plain, while 26 per- cent are found in the Chenier Plain. IMPORTANCE TO FISH AND WILDLIFE FISHERIES Louisiana leads the United States in volume of commercial fish- ery landings. Nearly 1.7 billion pounds (0.8 billion kg) of commer- cial fish and shellfish were landed in Louisiana during 1978 (National Marine Fisheries Service 1979). The bulk of this catch is composed of estuarine-dependent species in- cluding menhaden, Atlantic croaker, seatrout, spot, red drum, blue crab, brown shrimp, white shrimp, and American oyster. The LCR also sup- ports a large recreational fishery. Approximately 580,000 persons ex- pended over 5 million saltwater angling days in the area in 1975, spending over $35 million (U.S. Fish and Wildlife Service 1977). It has also been estimated that 6.9 million days of sport crabbing effort occur- red in the LCR in 1975 (U.S. Fish and Wildlife Service 1977). Ap- proximately 373,000 recreation days were spent sport shrimping in the LCR in 1968 (U.S. Fish and Wildlife Service 1976). WILDLIFE The Louisiana coastal marshes are of great importance to migratory waterfowl, wintering more than two- thirds of the entire Mississippi Flyway waterfowl population in recent years (Bellrose 1976) . Palm- isano (1973) noted that one-fourth of the North American puddle duck population winters in these wet- lands, with peak numbers of over 5.5 million of these birds recorded during December 1970. Coastal Louisiana's wetlands also support over one-half of the continental mottled duck population, with fall populations of 75,000 to 120,000 birds reported (Bellrose 1976). Diving ducks are also abundant in the Louisiana coastal marshes and adjacent waters during the fall and winter months. More than 90 percent of the Mississippi Flyway' s 870,000 lesser scaup winter in Louisiana, primarily in its coastal zone. (Bellrose 1976). In addition, near- ly 38 percent of the canvasbacks that winter in the Mississippi Fly- way occur in Louisiana, mostly in Six Mile and Wax Lakes of the Lower Atchafalaya Basin and Atchafalaya Delta (Bellrose 1976). Many ducks present in fall and spring are transients that utilize the LCR for 388 Miles Figure 1. Physiography of Louisiana Coastal Region (adapted from Morgan 1973) 389 feeding and resting enroute to or from Central and South America (Palmisano 1973) . The Louisiana coastal marshes and adjacent rice- fields have supported 369,000 lesser snow geese and 55,000 white-fronted geese in recent years (A.R. Brazda personel communication). The LCR wetlands provide im- portant habitat to numerous other migratory birds. Common game spe- cies include clapper rail, king rail, sora, common snipe, purple gallinule, and common gallinule. Non-game migratory species are also abundant in the area. A total of 148 nesting colonies of seabirds, wading birds, and shorebirds re- presenting 26 species and over 794,000 nesting adults were inven- toried in the LCR during 1976 (Portnoy 1977). In addition, ap- proximately 14 active bald eagle nests were recorded by Fish and Wildlife Service personnel in the LCR during 1980, representing the largest nesting concentration of this endangered species in the south-central United States. Because of its extensive coast- al wetlands, Louisiana has been the leading fur-producing area in North America as long as records have been kept (Lowery 1974). The Louisiana fur harvest accounted for nearly one-third of the Nation's fur take in the 1969-1970 season (U.S. Fish and Wildlife Service 1971). Accord- ing to the Louisiana Department of Wildlife and Fisheries (1978b), over 3.2 million pelts worth more than $24 million were taken in Louisiana during the 1976-1977 season. Musk- rat and nutria, primarily coastal species, accounted for nearly 90 percent of the pelts harvested dur- ing that period. Alligators in the LCR exceed 300,000 (Louisiana Department of Wildlife and Fisheries 1980a), per- mitting controlled hunting in much of the area. In 1979, 16,300 alliga- tors, worth approximately $1.7 mil- lion, were harvested in the LCR (Louisiana Department of Wildlife and Fisheries 1980b). The LCR supports extensive sport hunting and other wildlife-oriented recreation. For example, an esti- mated 676,000 man-days were spent waterfowl hunting in the LCR during the 1977-1978 season (Louisiana Department of Wildlife and Fisheries 1978a), and the 1980 demand for con- sumptive wildlife-oriented recreation in the LCR has been projected at 1.14 million man-days (U.S. Fish and Wildlife Service 1976). MAGNITUDE OF WETLAND DETERIORATION IN COASTAL LOUISIANA Gagliano and van Beek (1970) documented a net annual -land-loss rate of 16.5 mi (42.7km ) in the LCR. This estimate was based on a comparison of maps covering the periods 1931-1942 and 1948-1967. Using U.S. Geological Survey quad- rangle sheets and aerial photographs for the period 1960-1974, Adams et al. (1976) established a net annual marsh-loss rate in the Barataria Basin of the LCR estimated at 3,200 to 7,416 acres (1,295 to 3,001 ha). Craig et al. (1979) compared this rate reported by Adams et al. (1976) to the 1,942 acres (786 ha) reported by Gagliano and van Beek (1970) for this area, indicating an increase in the land-loss rate of 65 percent to 282 percent over the rate reported by the latter authors. Recent studies of wetland loss have been conducted in the Chenier Plain ecosystem of 390 southwest Louisiana and southeast Texas (Gosselink et al. 1979). Based on these studies, it was estimated that approximately 5,000 acres/yr (2,024 ha/yr) of natural and im- pounded marsh were converted to open water, spoil deposits, or agricultur- al or urban uses between 1952 and 1974 in the Vermilion, Chenier, Mer- mentau, and Calcasieu basins of southwest Louisiana and the Sabine Basin of southwest Louisiana and southeast Texas. A recent study (Wicker 1980) of the Mississippi Deltaic Plain Region (MDPR) conducted for the Fish and Wildlife Service's National Coastal Ecosystems Team and the U.S. Bureau of Land Mangement has produced alarming statistics. Preliminary analysis of data obtained from plani- metering habitat maps prepared for this study revealed that approxi- mately 464,500 acres (187,983 ha) of coastal marsh were lost in the Louis- iana portion of the MDPR between 1956 and 1978, for an annual loss rate of over 20,200 acres (8,175 ha) or (31.6 mi /yr) (Robert Ader 1980 personal communication) . Combining this esti- mate with the estimated marsh-loss rate of 5>,000 acres/yr (2,024 ha/yr) or 7.8 mi /yr (20.7 km /yr) for that portion of the Chenier Plain found in western Louisiana and extreme south- east Texas, it is estimated that the marshes of the entire LCR are being lost at an estimated rate exceeding 25,000 acres/yr (10, 118 ha/yr) , or over 39 mi yr (101.0 km /yr) . This is more than twice mi /yr (42.7 km /yr) the rate of 16.5 reported by Gagliano and van Beek (1970). CAUSES OF WETLAND DETERIORATION Wetland deterioration in the LCR is attributed to land loss and salt- water intrusion. According to Craig et al. (1979) land loss in the LCR results from an interaction of nat- ural and man-induced impacts. Natural land loss occurs through subsidence, compaction, and erosion of the sub- strate following cessation of active deltaic deposition (Morgan 1973). Barrier islands and tidal inlets buf- fer coastal marshes from stormy energy and regulate salinities. The erosion of barrier islands and widen- ing of tidal inlets have also been identified as causes of land loss (Craig et al. 1979). Numerous man- induced alterations have accelerated natural wetland loss. The construc- tion of federally financed navigation channels, mainline Mississippi River levees, and upstream diversions and flood control reservoirs have vir- tually eliminated overbank flooding along the Lower Mississippi River. Consequently, most of the riverborne sediments are being transported past formerly active deltas and into the deeper Gulf of Mexico (Gagliano and van Beek 1970). This loss of sedi- ment input has, except in Atchafalaya Bay, prevented large-scale delta building and has accelerated subsi- dence and erosion of existing marshes. Other human causes of wet- land loss include canal dredging and associated spoil disposal and drain- age of wetlands for agricultural pur- poses (Gagliano 1973) . Gagliano at- tributed approximately 25 percent of the total land loss in coastal Louis- iana during the past 30 years to oil and gas industry dredging. Saltwater intrusion, another major cause of wetland deterioration, is occurring in many areas of the LCR. This process has been docu- mented at numerous locations, such as Barataria Bay (Van Sickle et al. 1976) and along the Mississippi River-Gulf Outlet in southeast Louisiana (Fontenot and Rogillio 1970). Saltwater intrusion has wide- ranging adverse effects, such as al- lowing encroachment of the predaceous 391 southern oyster drill (Thais haemastoma) onto productive oyster reefs (Pollard 1973) and conversion of fresher marsh vegetation to more saline types. FISH AND WILDLIFE IMPLICATIONS OF WETLAND DETERIORATION FISHERIES The marshes of the LCR are ex- tremely important to the maintenance of its estuarine-dependent sport and commercial fisheries. These wet- lands produce vast amounts of organic detritus, an important trophic com- ponent of estuarine fish and shell- fish productivity (Darnell 1961; Odom et al. 1973). The marshes and asso- ciated shallow waters of the LCR are also important as nursery habitat for many estuarine-dependent species. This importance has been documented by numerous authors, such as Herke (1971), White and Boudreaux (1977), Rogers (1979), and Chambers (1980). There is growing evidence that the amount of marsh is the most important factor influencing estuarine-depend- ent fishery production. Turner (1979) reported that Louisiana's com- mercial inshore shrimp catch is directly proportional to the area of intertidal vegetation, and that the area of estuarine water does not seem to be directly associated with shrimp yields. He further noted that the loss of wetlands in Louisiana has a direct negative effect on fisheries. Although the effects are masked by large annual variations in yield, wetland losses in the LCR reported by Craig et al. (1979) are equivalent to 6.31 million pounds (2.86 million kg) of shrimp harvest "lost" over the past 20 years (Turner 1979). Lindall et al. (1972) presented evidence that shrimp and menhaden are being harvested at or near maximum sus- tainable yield. These species accounted for nearly 99 percent of the total volume of Louisiana's commercial fish and shellfish land- ings in 1976 (Plaisance 1977). Fur- ther evidence that this is occuring was presented by Harris (1973), who noted that any substantial decreases in marsh habitat will result in de- creased estuarine-dependent fishery production. An analysis of the de- pendence of menhaden catch on wet- lands in the LCR was conducted by Cavit (1979). The findings of this analysis suggest that menhaden yields are greatest in those LCR estuarine basins having the highest ratio of marsh to open water. Based on the evidence cited above, continued wet- land loss in the LCR could lead to serious declines in its estuarine- dependent fishery. WILDLIFE Wildlife dependent on the LCR marshes face serious habitat de- clines as a result of future land loss and saltwater intrusion. Losses of fresh to intermediate marsh (Chabreck 1972) or conversion of these wetlands to more saline types will adversely affect migratory puddle ducks, as relative abundance of these waterfowl in the LCR is highest in these marsh types (Palmisano 1973). Based on rather conservative projections of declines in habitat quality and abundance in the LCR, it has been estimated that demand for waterfowl hunting will exceed available supply by 454,000 man-days by the year 2020 (U.S. Fish 392 and Wildlife Service 1976). Habitat quality and quantity for other marsh birds will also be reduced by contin- ued wetland deterioration. Nutria comprised roughly 70 percent of Louisiana's total fur harvest between 1970 and 1975 (O'Neil and Linscombe 1975). Palmisano (1973) reported that nutria catch per acre is highest in fresh marsh, declining progres- sively in the intermediate, brackish, and saline marsh types. Alligator populations also reach peak levels in fresh to intermediate marshes (Palmisano et al. 1973). Accord- ingly, continued wetland deteriora- tion can be expected to result in declines in fur harvest and alligator populations, especially as land loss and salinity intrusion reduce fresher marsh acreage. DISCUSSION OF MEASURES TO REDUCE WETLAND DETERIORATION Except for regulation of devel- opment, the primary measures investi- gated to date for control of wetland deterioration in the LCR have in- volved diversion of Mississippi River water into adjacent marshes and estu- arine areas for salinity control and creation of new subdeltas. A plan for introduction of Mississippi River water into the subdelta marshes of southeast Louisiana was submitted by the U.S. Fish and Wildlife Service to the U.S. Army Corps of Engineers in 1959 (U.S. Fish and Wildlife Ser- vice 1959). This plan included a recommendation for the construction of four water control structures, having a combined discharge capacity of 24,000 cubic feet per second (cfs), to divert Mississippi River water for salinity control. The structures would have benefitted an estimated 264,500 acres (107,043 ha) of marsh and estuarine waters. The annual benefits of this plan in in- creased oyster yields, furbearer har- vest, and waterfowl utilization were estimated at $841,600, exceeding costs by 62 percent. Recognizing that the project was necessary to partially rectify wetland degradation brought about by the construction of federally financed Mississippi River mainline levees, the U.S. Fish and Wildlife Service (1959) recommended that the Mississippi River and Trib- utaries Project authorized by the Flood Control Act of 1928 be amended to recognize fish and wildlife as a project purpose and to include the service's freshwater introduction plan as an integral feature. That plan, now known as the "Mississippi Delta Region, Louisiana," project, was authorized by Public Law 89-298 on October 27, 1965. Detailed plan- ning of one of the four authorized diversion structures was initiated in 1969, but was suspended when local interests failed to furnish economic justification for their requested change in the location of that structure (U.S. Army Corps of Engi- neers 1975). It should be noted that, despite the obvious need for the pro- ject to mitigate the adverse effects of the Mississippi River mainline levees, the project is classified as "enhancement," making local interests responsible for 25 percent of the project costs. This has been cited by local interests as one reason for their reluctance to participate in the project. The most comprehensive treat- ment of measures for arresting land loss and salinity intrusion in the LCR is contained in a report prepared by Gagliano et al. (1973b) under contract to the U.S. Army Corps of Engineers. That study was conducted in conjunction with a broad evalua- tion of the LCR by an ad hoc in- teragency group and evaluated two primary measures for addressing wet- land deterioration, including: 393 (1) controlled introduction of Mis- sissippi River water into adjacent estuarine marshes and bays for salin- ity control and nutrient input; and (2) creation of subdeltas along the lower Mississippi River through con- trolled freshwater diversion into adjacent shallow bays. A multi-use management plan for south-central Louisiana was subse- quently developed (Gagliano et al. 1973a). This plan recommended cer- tain developmental controls, manage- ment and maintenance of barrier islands, erosion control, and surface water management including supple- mental freshwater introduction, management of existing runoff sur- pluses and controlled subdelta build- ing with diverted Mississippi River water and sediments. Despite the virtually universal recognition of the seriousness of the wetland deterioration problem in the LCR and the existence of plans to address that problem, no major feder- ally financed measures have been implemented. However, two ongoing federal water resource studies being conducted under the leadership of the U.S. Army Corps of Engineers offer considerable promise for large-scale supplemental freshwater introduction into the subdelta marshes of the LCR. These include the Louisiana Coastal Area Study and Mississippi and Louisiana Estuarine Areas Study. With regard to the latter study, prelimi- nary estimates by the U.S. Fish and Wildlife Service indicate that be- tween $4.4 and $5.2 million in annual benefits to fish and wildlife can be realized with a single large- scale diversion into the Lake Pont- chartrain-Lake Borgne area of south- east Louisiana (Fruge and Ruelle 1980). In 1979, the Louisiana Legis- lature enacted legislation directing the Secretary of the Louisiana De- partment of Transportation and Development to prepare a freshwater diversion plan for Louisiana. That plan is expected to complement any freshwater introduction measures implemented by Federal agencies. CONCLUSIONS AND RECOMMENDATIONS It is clear that the important fish and wildlife resources of the LCR are threatened by rapid, contin- ued degradation of its wetland habi- tat through land loss and saltwater intrusion. This problem is widely recognized by natural resource man- agers, scientists, and the public at large, and positive measures have been proposed to address it. How- ever, definitive action must be taken to implement these measures at the earliest possible date. Be- cause federally constructed flood control and navigation works have played a major role in the deteriora- tion of Louisiana's coastal wetlands, it would seem that mitigation of these adverse impacts should be accomplished primarily through the public works programs of the Federal Government. LITERATURE CITED Adams, R. D.; Barrett, B. B.; Black- mon , J . H . ; Gane , B . W . ■ Mclntire, W. G. Barataria Basin: geologic processes and frame- work. Baton Rouge, LA: Louis- iana State Univ. , Center for Wetland Resources,- Sea Grant publication no. LSU-T-76-006 1976; 117p. 394 Ader, R. U.S. Fish and Wildlife Service, National Coastal Eco- systems Team; Personal communi- cation; 1980 August 12. Bellrose, F.C. Ducks, geese and swans of North America. A Wild- life Management Institute book sponsored jointly with Illinois Natural History Survey. Harris- burg, PA: Stackpole Books; 1976: 543 p. Brazda, A.R. U.S. Fish and Wildlife Service, Office of Migratory Bird Management; Personal com- munication; 1981 March 16. Cavit, M.H. Dependence of menhaden catch on wetland habitats: a statistical analysis. NSTL Sta- tion, MS: U.S. Fish and Wild- life Service, Office of Biologi- cal Services, National Coastal Ecosystems Team; 1979; 12 p. Un- published report submitted to U.S. Fish and Wildlife Service, Ecological Services Field Of- fice, Lafayette, LA. Chabreck, R.H. Vegetation, water and soil characteristics of the Louisiana coastal region. Baton Rouge, LA: Louisiana State Univ. Agricultural Experiment Station. 1972; 72 p. Bulletin No. 664. Chambers, D. G. An analysis of nek- ton communities in the upper Barataria Basin, Louisiana. Ba- ton Rouge, LA: Louisiana State Univ.; 1980. 286 p. Thesis. Craig, N. J.; Turner, R. E. ; Day, J. W. , Jr. Land loss in coastal Louisiana. Day, J.W. , Jr.; Cul- ley, D. D., Jr.; Turner, R.E.; Mumphrey, A. J., Jr., eds . Pro- ceedings of the third coastal marsh and estuary management symposium; 1978 March 6-7; Louis iana State Univ. , Baton Rouge, LA. Louisiana State Univ. Division of Continuing Educa- tion, 1979: 227-254. Darnell, R. M. Trophic spectrum of an estuarine community based on studies of Lake Pontchartrain, Louisiana. Ecology 42(3): 553- 568; 1961. Fontenot, B. J., Jr.; Rogillio, H. E. A study of estuarine sportfishes in the Biloxi Marsh Complex, Louisiana. F-8 Completion Re- port, a Dingell-Johnson Project. Baton Rouge, LA: Louisiana Wild Life and Fisheries Commis- sion; 1970; 172 p. Fruge, D. W. ; Ruelle, R. Mississippi and Louisiana Estuarine Areas Study. A planning-aid report submitted to the U.S. Army Corps of Engineers, New Orleans Dist- rict, New Orleans, Louisiana. Lafayette, LA: U.S. Fish and Wildlife Service, Division of Ecological Services; 1980; 86 p. Gagliano, S. M. Canals, dredging, and land reclamation in the Louisiana coastal zone. Hydro- logic and geologic studies of coastal Louisiana. Baton Rouge, LA: Coastal Resources Unit, Center for Wetland Resources, Louisiana State Univ., 1973; 104 p. Report no. 14. Gagliano, S. M. ; Culley, P.; Earle, D. W. , Jr.; King, P.; Latiolais, C; Light, P.; Rowland, A.; Shlemon, R. ; van Beek, J. L. Environmental atlas and multi- use management plan for south- central Louisiana. Hydrologic and geologic studies of coastal Louisiana. Baton Rouge, LA: 395 Center for Wetland Resources, Louisiana State Univ., 1973a; 132 p. Report No. 18, Vol. 1. Gagliano, S. M. ; Light, P.; Becker, R. E. Controlled diversions in the Mississippi Delta System: an approach to environmental management. Hydrologic and geo- logic studies of coastal Louis- iana. Baton Rouge, LA: Coastal Resources Unit, Center for Wet- land Resources Unit, Louisiana State Univ., 1973b; 146 p. Re- port No. 8. Gagliano, S. M. ; van Beek, J. L. Geologic and geomorphic aspects of deltaic processes, Mississip- pi Delta System. Hydrologic and geologic studies of coastal Louisiana. Baton Rouge, LA: Coastal Resources Unit, Center for Wetland Resources, Louisiana State Univ., 1970; 140 p. Report no. 1 . Gosselink, J.G.; Cordes, C.L.; Par- sons, J.W. An ecological char- acterization study of the Che- nier Plain coastal ecosystem of Louisiana and Texas. Slidell, LA: U.S. Fish and Wildlife Service, Office of Biological Services; 1979. 3 vol. FWS/OBS 78/9 through 78/11. Harris, A. H. Louisiana estuarine- dependent commercial fishery production and values (regional summary and WRPA-9 and WRPA-10 analysis of production and habi- tat requirements). Report pre- pared for U.S. Department of Commerce, National Marine Fish- eries Service, Water Resources Division, St. Petersburg, FL: 1973; 36 p. Available from: National Marine Fisheries Ser- vice, St. Petersburg, FL. Herke, W. H. Use of natural, and semi-impounded, Louisiana tidal marshes as nurseries for fishes and crustaceans. Baton Rouge, LA: Louisiana State Univ.; 1971. Available from: Univer- sity Microfilms, Ann Arbor, MI; Publication no. 71-29,372. 264 p. Dissertation. Lindall, W. N., Jr.; Hall, J. R. ; Sykes, J. E.; Arnold, E. L. , Jr. Louisiana coastal zone: analyses of resources and re- source development needs in connection with estuarine ecology. Sections 10 and 13-- fishery resources and their needs. St. Petersburg Beach, FL: National Marine Fisheries Service Biological Laboratory; 1972; 323 p. Prepared for U.S. Department of the Army, New Or- leans District, Corps of Engi- neers, Contract no. 14-17-002- 430. Louisiana Department of Wildlife and Fisheries. 1977-78 water- fowl survey. Baton Rouge, LA: 1978a. 12 p. Louisiana Department of Wildlife and Fisheries. Wildlife resources of Louisiana. Baton Rouge, LA: 1978b; 34 p. Wildlife education bulletin no. 93. Louisiana Department of Wildlife Fisheries. Alligator regula- tions adopted by Louisiana Wildlife and Fisheries Commis- sion at its regular meeting held in New Orleans, Louisiana on Tuesday, July 29, 1980. New Orleans, LA: 1980a. 6 p. mimeo- graph. Louisiana Department of Wildlife 396 and Fisheries. News release no. 80-48, 1980b August 8. Lowery, G. H. , Jr. Fur in Louisiana. The mammals of Louisiana and its adjacent waters. Baton Rouge, LA: Published for Louisiana Wildlife and Fisheries Commis- sion, Louisiana State Univ. Press; 1974: 21-45. Morgan, J. P. Impact of subsidence and erosion on Louisiana coastal marshes and estuaries. Chabreck, R. H. , ed. Proceedings of the second coastal marsh and estuary management symposium; 1972 July 17-18; Louisiana State Univ., Baton Rouge, LA: Louisiana State Univ. Division of Contin- uing Education; 1973: 217-233. Palmisano, A. W. Habitat preference of waterfowl and fur animals in the northern gulf coast marshes. Chabreck, R. H. , ed. Proceed- ings of the second coastal marsh and estuary management sympo- sium; July 17-18; Louisiana State Univ., Baton Rouge, LA. Louisiana State Univ. Division of Continuing Education; 1973: 163-190. Palmisano, A. W.;Joanen, T. ; McNease, L. L. An analysis of Louis- iana's 1972 experimental alliga- tor harvest program. Paper pre- sented at 27th annual meeting of the Southeastern Association of Game and Fish Commissioners. Hot Springs, AR. ; 1973 October. National Marine Fisheries Service. Fisheries of the United States, 1978. Washington, D.C.: 1979; 120 p. Current Fisheries Stat- istics no. 7800. Available from: U.S. National Marine Fisheries Service, Washington, DC: N0AA-- S/T 79-183. Odom, W. E.; Zieman, J. C. ; Heald, E.J. The importance of vascular plant detritus to estuaries. Chabreck, R. H. , ed. Proceed- ings of the second coastal marsh and estuary management sympo- sium; 1972 July 17-18; Louisiana State Univ., Baton Rouge, LA. Louisiana State Univ. Division of Continuing Education; 1973: 91-114. O'Neil, T. ; Linscombe, G. The fur animals, the alligator, and the fur industry in Louisiana. New Orleans, LA: Louisiana Wildlife and Fisheries Commission; 1975; 66 p. Wildlife education bulle- tin no. 106. Plaisance, 0. Louisiana landings, annual summary 1976. Washing- ton, DC: National Oceanic and Atmospheric Administration, Nat- ional Marine Fisheries Service; 1977; 8 p. Current Fisheries Statistics no. 7222. Pollard, J. F. Experiments to re- establish historical oyster seed grounds and to control the southern oyster drill. New Orleans, LA: Louisiana Wild Life and Fisheries Commission, Oyster, Water Bottoms and Sea- foods Division, 1973: 82 p. Technical bulletin no. 6. Portnoy, J. W. Nesting colonies of seabirds and wading birds coastal Louisiana, Mississippi, and Alabama. Slidell, LA: U.S. Fish and Wildlife Service, Bio- logical Services Program; 1977; 126 p. FWS/OBS-77/07. Rogers, B. D. The spatial and temp- oral distribution of Atlantic croaker, Micropogon undulatus , 397 and spot, Leiostomus xanthurus , in the upper drainage basin of Barataria Bay, Louisiana. Baton Rouge, LA: Louisiana State Univ. ; 1979. 96 p. Thesis. Turner, R. E. Louisiana's coastal fisheries and changing environ- mental conditions. Day, J. W. , Jr.; Culley, D. D. , Jr.; Turner, R. E . ; Mumphrey, A. J., Jr., eds. Proceedings of the third coastal marsh and estuary man- agement symposium; 1978 March 6-7; Louisiana State Univ., Baton Rouge, LA. Louisiana State Univ. Division of Contin- uing Education; 1979: 363-370. U.S. Army Engineer District, Corps of Engineers, New Orleans, Loui- siana. Mississippi Delta Region Salinity Control Structure, Louisiana, condition of improve- ment, 30 June 1975. In Project Maps, Volume 2: Flood Control, Mississippi River and Tribu- taries. 1975 (p. 3-17A). U.S. Fish and Wildlife Service, Division of Ecological Services; 1976; 61 p. Unpublished. U. S. Fish and Wildlife Service. 1975 National Survey of hunting, fishing and wildlife associated recreation. Washington, DC: 1977; 91 p. Van Sickle, V. R. ; Barrett, B. B.; Ford, T. B.; Gulick, L. J. Bara- taria Basin: salinity changes and oyster distribution. Baton Rouge, LA: Center for Wetland Resources, Louisiana State Univ., 1976; 22 p. Sea Grant publication no. LSU-T-76-02. White, C. J.; C. J. Boudreaux. De- velopment of an areal management concept for gulf penaeid shrimp. New Orleans, LA: Louisiana Wildlife and Fisheries Commis- sion, Oysters, Water Bottoms and Seafoods Division; 1977; 77p. Technical bulletin no. 22. U.S. Fish and Wildlife Service. A plan for freshwater introduction from the Mississippi River into sub-delta marshes below New Orleans, Louisiana, as part of the Mississippi River and Tribu- taries review. Atlanta, GA: 1959; 48 p. Available from: U.S. Fish and Wildlife Service, Division of Ecological Services, Lafayette, LA. Wicker, K. M. Mississippi Deltaic Plain Region ecological charac- terization: a habitat mapping study. A user's guide to the habitat maps. U. S. Fish and Wildlife Service, Office of Bio- logical Services, 1980. FWS/ OBS - 79/07. 45p. + App. U.S. Fish and Wildlife Service. Fur catch in the United States, 1970: Washington, DC: 1971; 4p. Wildlife leaflet 499. U. S. Fish and Wildlife Service. Fish and wildlife study of the Loui- siana coastal area and the Atcha- falaya Basin Floodway. Appendix D, part 3: Sport fish and wild- life harvest. Lafayette, LA: DISCUSSION Question: Mark Crandle, Coastal Management Section-Louisiana. I'd like to ask somebody from the Corps if anybody has--it seems like funding is a major problem here — attempted to get this 25 percent max that the locals have to put up changed in any way? 398 Answer: (from the panel) Not that I know of but that's an excel- lent idea. I don't think that's the only hindrance to the implementation of the plan. It would still be dif- ficult, of course, but not impossible to construct such a site in a parish that did not want that site in that parish. I know certainly that's an area that the State of Louisiana could assist us in, either offering to cover that 25 percent, or convince local interests that they don't mind putting up the 25 percent, or if it happens to go to 100 percent Federal funding, then they ought not oppose the construction of such a site in their community. Question: Do you have any indi- cation of how the retention of the sediments in the Atchafalaya Bay wouldi change if you changed the major flow from the Atchafalaya to the Wax Lake Outlet? Would there be a change in the retention there? Answer: (from the panel) No, I just think it would change the loca- tion of deposition slightly. It's possible, yes, that it could since the reef does form sort of an impedi- ment over on the lower Atchafalaya River side, whereas on the Wax Lake side that's not necessarily the case. But I think you would still get even- tually a general fill of the bay be- hind the reef. Question: Clark Lozes , Plaque- mines Parish. My basic reason for attending is to find out what's happening on a national scale and to find out more about what's happening in the rest of the states. I am a little nervous so please bear with me on this. I'm not normally a public speaker, but I do have several ques- tions. In regard to introducing fresh water into the marsh, and es- pecially because we do have such a bad marsh, I see two basic concepts: one, we're trying to spend Federal money to improve a very small area in the whole United States. I think that this is good for the local community however, I think it can be served better. We have an area on the right descending bank of the Mississippi approximately 40 miles miles below the city of New Orleans called Empire that has a ship chan- nel and locks . We can easily di- vert the flow of Mississippi water into the marsh through the locks . This is an area that needs to be studied a little bit farther be- fore we go opening up new freshwater inflows. In addition to that at the Algiers Canal just south about mile 68 on the Mississippi River, there is the ability to take fresh-water from the river and introduce it through the bayou. This would not cost any great amount of money to do. It would require some coordination on both the U.S. Corps of Engineers, the marine biologists, and more than likely, other state agencies. One of our problems that we see is the lack of local government input. An ex- ample of this was last year when we had oyster fishing on what we call Quarantine Bay right adjacent to a bayou which is a freshwater inlet for oysters. The BODs indicated by the health department showed that the oyster reef should be shut down. The water being poured on the oyster reef was from a controlled structure put there by the Federal Government. We had closed down three other water control structures to stop BODs. It took us three and a half weeks to get the government to come down and close their water control structure. That's what we don't want to see- Federal Government interfering with the local fishermen. If it's time to close it down, Gentlemen, it's time to close it down. It's not three weeks later that affects the 399 local fisherman. That's our biggest fear. Over any type of federally- funded projects, how much can the local community input and control the effects that are basically theirs? Answer: (from the panel) the idea behind these projects is to, in the long term, increase the overall availability of areas suitable for things like growing oysters. Over the years the salinity intrusion has gradually shifted the areas suitable for growing oysters inland. If you really divert large amounts of fresh- water from those areas they are going to be destroyed but in the long run the idea is to have a larger area available and increased overall pro- duction. But if you do have these mass amounts of freshwater diver- sions, you are going to wipe out some areas that presently exist. In some way those people will have to be com- pensated. But it's long-term, over- all benefits that are being looked at. You'll have, theoretically, a much larger area available for those types of things than you do now. Question: It's been my experi- ence that there was little local in- put into most of the planning of the Corps of Engineers and other federal projects. Were local people pretty well excluded from a lot of the nego- tiations in this case, or was it well publicized, or what was the case? Answer: (from the panel) I haven't been affiliated with these studies that long and I'm not even familiar with when the last public meeting was held. I know that some of the guys from Fish and Wildlife Service have been involved a lot longer than I have, and can address that, relative to when the last public meetings were held down in Plaquemines Parish. If they would be kind enough to bail me out. Comment: Scott Nixon, Rhode Island. I can't resist after hearing all of this to make an unpopular ob- servation. And that is when we hear there's too much freshwater over on one side, and then there's not enough on the other side and the Corps has done all this work of building dams and levees and moving the water around, we want them to build more and move it around somewhere and bail us out because we screwed that up and we've got problems with the water quality. And maybe that will work and maybe that won't, but I'm struck by hearing all of this this morning that when each of these projects was undertaken we had a glowing report as to what it was going to do for us. And yet we find afterwards that there were all sorts of fallouts that we hadn't anticipated and now we've got all kinds of other problems and we want to do another six projects to get us out of that one. And my impression from reading the lit- erature is that we really don't understand these systems and there is a tremendously complex environment in coastal Louisiana to make a really compelling case. That we know what is going to happen if we put fresh water here, there, or somewhere else, and that some of the cost-benefit calculation that must go into doing the kinds of freshwater studies rest on the assumption of what we're go- ing to get in terms of fisheries yields for moving the freshwater somewhere else and promoting one kind of wetland over another one. And, at least, in that area we really don't have a good case for a lot of those linkages that people are supposing are there. Somebody mentioned Gene Turner's paper to- day, but that's an awfully slim kind of evidence to bring forward for spending millions and millions of dollars of Federal money. So an outsider to Louisiana, I'm not all 400 that sure that I'm anxious about having them spend all that money either. Comment: Mark Crandle, Coastal Management. Increased production is going to be an added benefit if it exists. But what we're dealing with here is the physical loss of land, in terms of hurricane protection and many other things. That we're actu- ally just losing land mass, whether or not it's tied to fishery produc- tions or not. And we have to do something to address that problem specif icaly. It's nice to be able to justify your problem by saying well, we're going to have more shrimp, we're going to have more oysters, and more of this. But there is a very real problem that has abso- lutely nothing to do with the fish- eries production and that's physi- cal protection of the coastline of Louisiana . 401 CHAPTER 6 FISHERIES MANAGEMENT AND FRESHWATER INFLOW 402 A NEW APPROACH TO DETERMINING THE QUANTITATIVE RELATIONSHIP BETWEEN FISHERY PRODUCTION AND THE FLOW OF FRESH WATER TO ESTUARIES Joan A. Browder Office of Fishery Management, Southeast Fisheries Center National Marine Fisheries Service, Miami, Florida Donald Moore Environmental Assessment Branch, Southeast Region National Marine Fisheries Service, Galveston, Texas ABSTRACT Freshwater inputs to estuaries appear to enhance the production of marine organisms, because the highest marine standing stocks along shore- lines are found in or near estuaries, which receive freshwater inputs. Despite this apparent connection, ef- forts to quantify the role of fresh- water in estuarine production not only have contradicted one another but have, in some cases, been con- tradictory to the basic concept of the value of freshwater inflows to estuarine production. In this paper we describe the water regimes, water management problems, and related estuarine research of several dis- tinct regions of the Gulf of Mexico, from south Texas to south Florida, and then suggest an approach to ex- amining the role of freshwater in estuaries that could lead to a uni- fying principle applicable to all situations . INTRODUCTION Coastal areas receiving fresh water are important to the production of fish and shellfish. The relation- ship between freshwater inflow and production is recognized but has been difficult to quantify. Fishery man- agers have few guidelines and little information to evaluate the effect of water management projects on fish- eries, but they must decide how much water can be diverted or how much the seasonally of flow can be altered without reducing estuarine produc- tivity. "Production functions" quanti- tatively relating fish production to freshwater flow under various circum- stances are needed. Although the functions may differ for each estu- ary and each species, determining such functions for even one estuary would be valuable in establishing a methodology. Determining production functions for several estuaries may lead to the development of a genera- lized model applicable to any estu- ary. Such a model surely must incor- porate hydrologic, meteorologic, and hydrodynamic concepts as well as physiological and ecological informa- tion and will therefore require an interdisciplinary effort. This paper will (a) provide a brief history of scientific work done in the Gulf of Mexico that relates to this problem; (b) summarize some re- cent work in Florida, Louisiana, and 403 Texas; (c) suggest new perspectives; (d) establish the rationale for an interdisciplinary approach; and (e) present a research outline. HISTORICAL OVERVIEW Activities of man that affect the quantity and/or timing of the flow of fresh water to estuaries in- clude: (1) dams for irrigation and power; (2) diversions; (3) canals in uplands; (4) deforestation; (5) clearcutting; (6) grazing; (7) road construction; and (8) paving (as in urban development). Ways in which these activities affect flow are shown in Table 1. All activities that increase peak flow and decrease dry season flow change the timing of flow by decreasing the lag between rainfall and runoff. Studies examining the potential effects of such changes fall into several types: (1) laboratory studies relating growth rates and mortalities of spe- cific organisms to salinity and tem- perature ; (2) field studies determining the frequencies and abundances of cer- tain organisms at various salinities and temperatures; (3) statistical studies determining estuarine food chains; (4) statistical studies of the re- lationships between landings and prior salinities or river discharge rates (effects on recruitment). Findings of these and related studies are summarized as follows: (1) Salinity-occurrence ranges, tol- erance ranges, and optima have been determined for a number of estuarine species . (2) Certain synergistic effects of salinity and temperature have been established. (3) Many organisms occurring in es- tuaries can withstand wide fluctu- ations in salinity. High calcium concentrations improve the capabil- ity of estuarine organisms to toler- ate near-freshwater conditions. (4) Estuaries are nursery grounds of many fish and invertebrate species that primarily occur, spawn, and are harvested offshore. (5) Salinity gradients partition estuarine habitat between different species and (possibly) different co- horts of the same species. (6) Low salinities (and possibly high salinities) reduce predation and parasitism on American oysters. Al- though difficult to demonstrate, ju- venile fishes and invertebrates may be protected from predation by sa- linity extremes. (7) Terrestrial detritus flushed in- to estuaries by the flow of fresh wa- ter forms the base of a major estu- arine food chain. (8) Significant relationships be- tween fishery yields and freshwater flow have been demonstrated by cor- relation-regression techniques for a number of estuaries and species. The correlations have been positive in some estuaries and negative in others and have been positive for some spe- cies while negative for others. 404 Table 1. Effects of anthropogenic activities on the quantity of freshwater flow to estuaries. 3 3 o o r- 1 rH 4-1 4-1 d 3 C 3 3 o o 3 O o O co 1— 1 o w 1—1 rH 03 m r— I CO 4-1 4-> 4-1 4-1 > +J CO >> +J 4-1 4-1 01 S-l O 11 s-l o 01 OJ ft T3 j-> ft T3 4-1 4-> >> o CO 4-> o o ex CO >> CO 3 J3 4-1 10 g ■H o CO T3 O >• T3 tt C < CO 3 1/) CO U 1 ^ -a ° S^ „ >> E u <0 aj s-i -C oo co <0 -H •H 4_| TJ 4-1 s o o r-t c 4-1 O 1 -H >> ^ oo u S-i 3 3 o 1—1 4-1 3 ■H S-l oj 4-> «) s XI • VI 4-1 01 «J i-i 4-> 4-1 •H ,£) 4-1 m O XI ft >» •H S-l XI 03 m S-l 4-1 00 «J 4-4 ■H o T3 «j r- 1 01 0) S-l -o CO o E 3 o 4J 3 4-1 & U 4-> 0) a 4-1 o 4-1 i 0) 4-1 3 CO ft 4J a • l-l •H XI O) 00 r-l 3 ft O E S-l •H -= CO 4-1 d • o CM ■H 4-> 0) U S-i 3 3 ■a oo o ■H U fn ft 422 Such a study should have five data-gathering elements: (1) moni- toring of freshwater flow rates; (2) measurement of vertical profiles of salinity, temperature, oxygen, and current direction and velocities; (3) measurement of detrital biomass and decomposition rates; (4) mapping of isohalines and quantification of area between isohalines periodically during the nursery season; (5) map- ping and quantification of poten- tially productive habitat area, based on physical and biological features, at different levels of high tide; and (6) monitoring of fishery yield and effort. In addition, we should also measure the input rates of nutrients, detritus, sediments, and toxic com- pounds . Some of the potential relation- ships that should be explored through statistical analysis and computer modeling are: (1) "Production area" (defined as the area of overlap of the favorable salinity band and favorable stationary physical and biological habitat features) vs. freshwater flow during the nursery season; (2) stratification vs. fresh- water flow; (3) fishery production vs. production area; (4) fishery production vs. area of marsh; (5) detrital decomposition vs. stratifi- cation; (6) recruitment vs. currents during critical periods of postlarval transport; and (7) fishery production vs. water quality. Such studies, conducted in a number of gulf coast estuaries and employing ocean engineers, physical oceanographers , remote sensing spe- cialists, systems ecologists, hydrol- ogists, geologists, and fishery biol- ogists could contribute significantly to a quantitative understanding of the role of fresh water in fishery production. ACKNOWLEDGEMENTS The authors appreciate the as- sistance of Bernard Yokel, Rookery Bay Marine Research Station, Naples, Florida; Peter Schroeder, South Florida Environmental Research Foundation, Don Allen, James Zuboy, and Lynn Pulos of the National Marine Fisheries Service, Miami, Florida, and others who contributed to this report. We thank Jeanette Bass, National Marine Fisheries Service, Miami, Floirda, for typing the manu- script. LITERATURE CITED Allen, D. M. ; Hudson, J.H.; Costello, T.J. Postlarval shrimp (Penaeus) in the Florida Keys: species, size, and seasonal abundance. Bull. Mar. Sci. 30:21-33; 1980. Barrett, B. B. ; Gillespie, M. S. 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Louisiana coastal zone: analyses of resources and resource devel- opment in connection with estua- rine ecology. Sections 10 and 13, Fishery resources and their needs. Report of the commerical fishery work unit of the Nation- al Marine Fisheries Service to the U.S. Army Corps of Engineers (Contract #14-17-002-430); 1972; 320 p. Located at: NMFS, South- east Regional Office, 9450 Koger Blvd., St. Petersburg, FL 33702. Livingston, R.J. Diurnal and season- al fluctuations of organisms in a north Florida estuary. Estua- rine Coastal Mar. Sci. 4:373- 400; 1976. Livingston, R.J.; Iverson, R.L.; Es- tabrook, R.H.; Keys, V.E. Tay- lor, J. , Jr. Major features of the Apalachicola Bay system: physiography, biota, and re- source management. Fla . Sci. 37: 245-270; 1974. Hicks, D. B. Appendix D-l - Public health. The Naples Bay study. Available from Collier County Conservancy, P.O. Box 2136, Naples, FL 33939. 1979b: 15 p. Hildebrand, H. H. ; Gunter, G. 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Current Fishery Statistics Nos . 3309, 3627, 3901, 4156, 4529, 4962, 5232, 5616, 5923, 6423, 6723, 7223, and Washington, D.C.: 1962- 4675, 6124, 7523. 1977a. National Marine Fisheries Service, NOAA, U.S. Dept. Comm. Gulf coast shrimp data. Annual Sum- maries. Current Fisheries Sta- tistics Nos. 3358, 3515, 3784, 4111, 4411, 4781, 5107, 5412, 5712, 5925, 6126, 6425, 6725, 6925, 7225, and 7523. Washing- ton, D.C. : 1962-1977b. National Marine Fisheries Service, NOAA, U.S. Dept. Comm. Prelimi- nary report. Fisheries of the United States, 1978. Current Fishery Statistics No. 7800. Washington, D.C: 1979; 120p. Odum, H.T.; Odum, E.C. Energy basis for man and nature. New York: McGraw-Hill; 1976. Odum, W.E. in a 1971. Tech. from: Pathways of energy flow south Florida estuary. Univ. Miami Sea Grant Bull. No. 7; Available University of Miami, Ro- senstiel School of Marine and and Atmospheric Science, 4600 Rickenbacker Causeway, Miami, Fl 33149. Parker, R.H. Changes in the inver- tebrate fauna, apparently attri- butable to salinity changes, in the bays of central Texas. J. Paleont. 29:193-211; 1955. Pearse, A.S.; Gunter, G. Salinity. Hedgpeth, J.W. , ed. Treatise on marine ecology and paleoeco- logy. Geol. Soc. Am. Mem. 67. Washington, D.C: American Geo- logical Society; 1957: 129-158. Ray, S.M. Biological studies of Dermocystidium marinum, a fun- gus parasite of oysters. Mono- graph in biology. Rice Institute Pamphlet, Special Issue. Hous- ton, TX: 1954; 114p. Reid, G.K.; Hoese, H.D. Size distri- bution of fishes in a Texas es- tuary. Copeia 1958: 225-231. 427 Sheridan, P. F. ; Livingston, R. J. Cyclic trophic relationships of fishes in an unpolluted river- dominated estuary in north Florida. Livingston, R. J., ed. Ecological processes in coastal and marine systems. New York: Plenum Press; 1979: 143-161. Simmons, E.G. An ecological survey of the upper Laguna Madre of Texas. Publ. Inst. Mar. Sci. Univ. of Tex. 4:156-200; 1957. Simmons, H. B. Some effects of up- land discharge on estuarine hy- draulics. Proceedings, American Society of Civil Engineers 81: Paper 792; 1955. Simpson, B. Appendix F-Engineering. The Naples Bay study. 1979; 27 p. Available from Collier County Conservancy, P.O. Box 2136, Naples, FL 33939. Stokes, G.M. The distribution and abundance of penaeid shrimp in the lower Laguna Madre of Texas, with a description of the live bait shrimp fishery . 1974; 32 p. Tex. Parks Wildl. Dept. Tech. Ser. 15. Sutcliffe, W.H. Some relations of land drainage, nutrients, parti- culate material, and fish catch in two eastern Canadian bays. J. Fish. Res. Board. Can. 29: 357-362; 1972. Sutcliffe, W.H. Correlations between seasonal river discharge and lo- cal landings of American lobster (Homarus americanus) and At- lantic halibut (Hippoglossus hippoglossus) in the Gulf of St. Lawrence. J. Fish. Res. Bd . Can. 30: 856-859; 1973. Sykes, J.E.; Finucane, J.H. Occur- rence in Tampa Bay, Florida, of immature species dominant in Gulf of Mexico commercial fish- eries. U.S. Dept. Inter. Fish Wildl. Serv. 1966. Fish. Bull. 65: 369-379. Tabb, D. B. ; Dubrow, D. L. ; Manning, R. B. The ecology of northern Florida Bay and adjacent estu- aries 1962. Fla. St. Bd. Con- serv. Tech. Serv. 37. Tenore, K. R. ; Hanson, R. B. Avail- ability of detritus of different types and ages to a polychaete macroconsumer , Capitella capi- tata . Limnol. Oceanogr. 25:553- 558; 1980. Texas Department of Water Resources. Sabine-Neches estuary: a study of the influence of fresh water inflows. LP-116. 1979a Dec. Draft report. Available from: P.O. Box 13087, Capitol Station, Austin, TX 781711. Texas Department of Water Resources. Trinity-San Jacinto estuary: a study of the influence of fresh- water inflows. LP-113. 1979b Dec. Draft report. Available from P. 0. Box 13087, Capitol Station, Austin, TX 78711. Texas Department of Water Resources. Lavaca-Tres Palacios estuary; a study of the influence of fresh- water inflows. LP-106. 1979c Sept. Draft report. Available from: P. 0. Box 13087, Capitol Station, Asutin, TX 78711. Texas Department of Water Resources. Guadalupe estuary: a study of the influence of freshwater in- flows. LP-107. 1979d Oct. Draft 428 report. Available from: P. 0. Box 13087, Capitol Station, Austin, TX 78711. Texas Department of Water Resources. Nueces and Mission-Aransas es- tuaries: a study of the in- fluence of freshwater inflows. LP-107. 1979e Nov. Draft re- port. Available from: P. 0. Box 13087, Capitol Station, Austin, TX 78711. Texas Department of Water Resources. The influence of freshwater in- flows upon the major bays and estuaries of the Texas gulf coast. LP-115. 1979f Dec. Executive Summary. Available from: P. 0. Box 13087, Capitol Station, Austin, TX 78711. Thomas, T.M. A detailed analysis of climatological and hydrological records of south Florida with reference to man's influence up- on ecosystem evaluation. Univ. Miami, Tech. Rep. 70-2: 1970; 80 p. Available from: University of Miami Rosenstiel School of Marine Science, 4500 Ricken- backer Causeway, Miami, FL 33149. van de Kreeke, J. Appendix C - Hydro- graphy. The Naples Bay study 1979; 43 p. Available from Col- lier County Conservancy, P. 0. Box 2136, Naples, FL 33939. Van Sickle, V. R. ; Barrett, B. B.; Ford, T.B.; Gulick, L.J. Bara- taria Basin: salinity changes and oyster distribution. Sea No. LSU-T-76-002: Available from: Wetland Resources , State University, Grant Publ. 1976 22p. Center for Louisiana Baton Rouge, LA. Venkataramiah, A.; Lakshmi, G. J.; Gunter, G. Studies on the ef- fects of salinity and tempera- ture on the commercial shrimp, Panaeus aztecus Ives, with special regard to survival lim- its, growth, oxygen consumption and ionic regulation. Ocean Springs, MS: Gulf Coast Re- search Laboratory. Contract Rep. H-74-2: 1974. 134 p. Con- tract Report. Available from: U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. Turner, R. E. Intertidal vegetation and commercial yields of penaeid shrimp. Trans. Am. Fish. Soc. 106:411-416; 1977. van Beek, J. L., Gagliano, S. M. , Delta-building potential of the Colorado River central Texas. Contrib. No. DACW-64-79 -C-0024. Append. I - Delta growth study. Mouth of Colorado River, Texas. Draft Phase 1 General Design Memorandum and Environmental Impact Statement (Diversion Features); Galveston, TX: U.S. Army Engineer District; 1980. Wallace, D.H. Sexual development of the croaker, Micropogon undula- tus , and distribution of the early stages in the Chesapeake Bay. Trans. Am. Fish. Soc. 70: 474-482; 1940. White, C.J.; Perret, W.S. Short term effects of the Toledo Bend Pro- ject on Sabine Lake, Louisiana. Mitchell, A.L., ed. Proceedings, 27th Annual Conference, S.E. Assoc. Game Fish Comm. ; 1973 October 14-17. Hot Springs, AR: 1974; 710-721. 429 Wiersema, J.M. ; Mitchell, R.P. A sur- vey of the Sabine Lake hydrogra- phy as it relates to the commer- cial fishery. Sabine Power Sta. Ecol. Prog. Vol. 2. TRACOR Proj . No. 077-004-12; Doc. No. T73-AU- 9506-U. 1973; 54. Available from: Espey, Huston & Associ- ates, Inc., P. 0. Box 519, Aus- tin, TX 78767. Yokel, B. Appendix E - Biology. The Naples Bay study 1979; 54p. Available from Collier County Conservancy, P.O. Box 2136, Na- ples, FL 33939. Zein-Eldin, Z.P.; Griffith, G.W. An appraisal of the effects of sa- linity and temperature on growth and survival of postlarval pen- aeids. Mistakidas, M.N. , ed. Proceedings on the world scien- tific conference on the biology and culture of shrimps and prawns, Mexico City, 1967 June 12-21. Rome: Food and Agri- culture Organization of the Uni- ted Nations. FAO Fish Rep. 57; 1969; 1015-1026. DISCUSSION Question: A question directed to Joan Browder: If you would, share some of your plans perhaps for con- tinuing your research. Answer: We were thinking that the study could have five data- gathering elements; one would be the monitoring of freshwater flow rates. Two would be measuring of vertical profiles of salinity, temperature, oxygen, and current direction and velocities. Three would be the measures of the detrital biomass and detritus decomposition rates. Four would be the mapping of the iso- halines and the quantification of the area between isohalines periodi- cally during the nursery season. This is where we would utilize the remote sensing techniques in combination with some field measurements. Five would be mapping and quantif icaton of potentially productive habitat areas based on physical and biologi- cal features at different levels of high tide. This is measuring the stationary habitat features, the areal stationary habitat that we consider to be important to differ- ent estuarine organisms. And then the monitoring of fishery yield and effort would be number six. In addition, of course, we should not neglect to measure the input rates of the detritus, the nutrients, and sediments and toxic compounds because we need to keep tabs on these too. Now, some of the potential relation- ships that should be explored through both statistical analysis and com- puter modeling once we begin to gather this data are production area, which we have defined as the area of overlap of the favorable salinity band and the favorable stationary physical and biological habitat features. Look at that versus fresh- water flow during the nursery season. Look at stratification versus fresh- water flow, look at production areas versus stratification, look at fish- ery production versus production area, and look at fishery production versus the area of marsh. Look at detrital decomposition versus strati- fication or degree of stratification. And look at recruitment into the estuary versus the currents that occur during critical periods of post larval transport. And then look at fishery production versus water quality. 430 TEXAS SHRIMP FISHERIES AND FRESHWATER INFLOW Ralph Rayburn Texas Shrimp Association Austin, Texas ABSTRACT The shrimp industry is a signif- icant industry in Texas . The econom- ic impact of shrimp to this State was approximately one-half billion dol- lars in 1979. The continued viabil- ity of this fishery is directly re- lated to the well being of the criti- cal marsh and estuarine habitats. Wa- ter managers must therefore consider this impact in all planning pro- cesses . INTRODUCTION The State of Texas has long held a reputation as a major pro- ducer of animal protein for the Nation. While in the public's mind this notoriety might be thought to result from only the production of beef, it should be noted that Texas is also a leader in the har- vesting of seafood. According to statistics supplied by the National Marine Fisheries Service in their publication Fisheries of the United States 1979 , Texas produced million pounds of seafood in 84.9 1979 with a value of $160.2 million. Of this, approximately 42 million pounds were shrimp with a value of $152 million (Farley personal com- munication) . This exvessel value represents an economic impact of approximately $500 million per year. HISTORY OF THE SHRIMP FISHERY The shrimp fishery originated in the bays and estuaries of the Gulf of Mexico. Fishery pioneers used large drag seines set close to shore and hauled by men or horses. Using this method, shrimp fish- ing was worthwhile only when shrimp were abundant near shore. The otter trawl was introduced into the shrimp fishery between 1912 and 1917. Using this gear, the fishermen continued to shrimp entirely in bays and shallow water, however, the otter trawl did reduce the seasonality of the fishery. Eventually, the in- dustry expanded and fishing grounds in the offshore region were dis- covered . As the industry developed from its conception along the coastal shores to its current status as a multi-million dollar contributor to the economy, two distinctive forms emerged. These forms are known as the bay shrimp industry and the gulf shrimp industry. Each indus- try has its own character and per- sonality. In addition, harvesting practices vary considerably in the two groups based on the importance of the particular shrimp species and the growth period within which harvesting takes place. There are three shrimp which basically species of support the 431 commercial shrimp fishery. These are Penaeus aztecus Ives, the brown shrimp, Penaeus setiferus Linnaeus, the white shrimp, and Penaeus duor- arum Burkenroad, the pink shrimp in the Gulf of Mexico (Van Lopik et al. 1980). Adult brown shrimp and, in some cases, white shrimp are caught by the offshore operators while ju- venile brown shrimp and white shrimp are caught by the inshore shrimpers. The annual catches of these dominant species tend often to be highly variable, associated to a great degree with environmental con- ditions. The effects of the environ- mental factors on the brown, white and pink shrimp are most pronounced during their critical estuarine- growth phase (Van Lopik et al. 1980). RELATIONSHIP OF THE SHRIMP INDUSTRY TO FRESHWATER INFLOWS To understand the importance of freshwater inflows and the resulting marsh area vitality to the shrimp industry, it is necessary to review the life cycle of the commercial penaeid shrimp. Current thought is that these shrimp spawn offshore in the Gulf of Mexico. The eggs hatch into the first of three larval stages. For 15 to 20 days, the shrimp larvae drift helplessly with the prevailing currents, hopefully terminating their journey at the en- trance to a bay system. The larval shrimp then molt into postlarvae and begin another migration to the upper bays and estuarine areas. With favorable conditions, the ju- venile shrimp grow rapidly in these areas. As the shrimp near maturity they begin to migrate through the bays and reenter the Gulf. Here spawning takes place and the cycle is reinitiated. According to Van Lopik et al. (1980), the weakest link in this cy- cle is the estuarine-growth phase. In this area, local fluctuations in temperature and salinity could po- tentially drastically effect both the availability of marsh suitable for growth and the actual growth rate of the shrimp. In addition, man-made al- terations such as impoundments , bulk- heading and alterations in freshwater discharges can accentuate the fluc- tuations causing considerably more detrimental impact. Turner (1977) has observed that there is a direct relationship between actual marsh acreage and yield of shrimp. This work is in harmony with that of Barrett and Gillespie (1973) which shows that the annual brown shrimp production in Louisiana is correlated with the acreage of marsh having waters above 10 ppt salinity. It appears from these findings that yields of the three major com- mercial species of shrimp in the Gulf of Mexico are dependent on maintenance of healthy estuarine marshes, mangrove areas and grass- beds in their natural state. Speci- fically, these areas provide post- larval, juvenile and subadult shrimp with food and protection from preda- tors as well as assist in main- tenance of the essential gradient between fresh and salt water (Van Lopik et al. 1980). A key element to the vitality of a marsh or estuary is in its very definition which speaks to the need for fresh water (Chapman 1972). This mixing of river waters and seawater 432 creates a nutrient sink of sulfates, carbonates, phosphorus and nitro- genous compounds (Copeland 1966) . In addition, large amounts of detritus are washed into the estuary by the river flow. This detritus is a principal element in the food web of estuarine ecosystems (Copeland 1966). There is some evidence that the various species of shrimp dif- fer in their affinity to freshwater inflow as it is translated into sa- linity regimes. In fact, Gunter et al. (1964) have shown that salinity may be a limiting factor in the dis- tribution and abundance of the com- mercially important penaeid species. In their studies, juvenile P. az- tecus were most abundant in es- tuarine waters of 10 to 20 ppt sa- linity whereas P. setiferus were more abundant in waters below 10 ppt and P. duo ra rum tended to reach a larger abundance in waters greater than 18 ppt. These ob- served preferences are clearly de- picted in species composition of the catch. Statistics tend to show the greatest concentration of brown shrimp to be off Texas where bay salinities are generally high- er. In Louisiana white shrimp are dominant due in part to the rela- tive freshness of the inside wa- ters, while pink shrimp appear to be more abundant in the catch off southern Florida where salinities approach oceanic conditions (Gun- ter et al. 1964). Gunter and Hildebrand (1954) showed a correla- tion between the catch of white shrimp on the Texas coast and the average rainfall for the State. Their results show a significant correlation between the rainfall of the previous two years and the catch of white shrimp. Copeland (1966) also showed that an increase by similar fluctuations in shrimp catch, generally after a two year period. Williamson (1977) stated that in San Antonio Bay, brown shrimp abundance in May through July was not affected by inflows in the May to June period or those from the previous September and October time frames. White shrimp on the other hand did vary positively in August with increases in the spring in- flows. There also appeared to be some enhancement of white shrimp numbers by fall inflows of the pre- vious year. White and Perret (1973) show- ed that the timing of inflow is also important. In their eval- uation of the effects of the Toledo Bend Project on Sabine Lake, they attributed the reduc- tion in catch for the brown and white shrimp to operational pro- cedures of the dam. Historically, heavy discharges occurred during spring and tapered off during the summer. The operating procedures of the dam changed this pattern by holding back the inflow surge until mid-May. This alteration has produced a near freshwater sit- uation within Sabine Lake which has devastated the brown and white shrimp populations. IMPLICATIONS TO PLANNING AND MANAGEMENT There continue to be ever in- creasing demands for the available surface water. Frequently the need to allocate water to the es- tuary is overlooked. Fortunately, it appears that many water mana- gers now see the need for consider- ing freshwater and associated nu- trient flows into the marsh areas to 433 preserve the valuable fishery re- sources. Water certainly is a pre- cious commodity which has long been taken for granted. Water uses must be more efficiently managed. No doubt there are methods of managing flows into estuaries to preserve or even enhance the fisheries. As was mentioned above, brown and pink shrimp tend to prefer a higher salinity than do white shrimp. Because brown shrimp tend to dominate the Texas catches the water manager might justify in- creased allocation of surface wa- ter upstream in order to increase the salinity and thereby benefit the brown shrimp. The fallacy in this position is that such actions would be to the detriment of the white shrimp crop. Under the cur- rent situation, the population of brown shrimp and white shrimp tend to complement each other. Much as a farmer planting two crops, if one fails due to unfavorable envi- ronmental conditions the other may be successful enough to carry the farmer to the next season. The major crops in the the case of the Texas shrimp fishery are brown and white shrimp. Although brown shrimp are reported to spawn throughout the year, the high spawning periods are distinct from those of the pink or white shrimp. The staggered nature of peak spawning periods between the avail- able species allows for the pos- sibility of maintaining vitality within the resource. Uncontrol- lable environmental conditions may impact one crop but not the other. shrimp populations continue to be harvested by the small near-shore operators especially during the fall open season in the bays where white shrimp are predominant in the har- vest. The more effective management of inflow to estuaries might be a solution to the ever increasing re- quirements placed on surface water. This effort however, must be based on sufficient information to maintain and enhance the important marine fisheries . CONCLUSIONS Sufficient information is available to show the importance of freshwater inflow to the vital- ity of the Texas shrimp industry. While ever-increasing requirements are being placed on the surface water resources, the need for bal- anced salinity regimes as well as sufficient nutrient and sediments to maintain a sound habitat should be paramount in the allocation process . Water management agencies, fish- ery resource protection agencies and the fishing industry should maintain a close working relationship to in- sure vitality of the estuaries and the significant fisheries resource. LITERATURE CITED Another consideration in main- taining both the brown and white shrimp populations is the socioeco- nomics of the industry. While it is true that brown shrimp represent the higher level of catch, the white Barrett, B.B.; Gillespie, M.C. Pri- mary factors which influence commercial shrimp production in coastal Louisiana. La. Dept. Wildlife and Fish. Tech. Bull. 9:28; 1973. 434 Chapman, C. R. The impact on estu- aries and marshes of modifying tributary runoff. Chabreck, R.H. , ed. Proceedings of the coastal marsh and estuary man- agement symposium. 1972: 236p. Copeland, B.J. Effects of decreased river flow on estuarine ecology. J. Water Poll. Contr. Fed. 1831- 1839:1966. Gunter, G. ; Christmas, J.Y. ; Kille- brew, R. Some relations of sa- linity to population distribu- tions of motile estuarine orga- nisms with special reference to penaeid shrimp. Ecology 45(1): 181-185; 1964. Gunter, G. ; Hildebrand, H.H. The re- lation of total rainfall of the State and catch of the marine shrimp (Penaeus setiferus) in Texas waters. Bull. Mar. Sci. Gulf Caribb. 4:95; 1954. Farley, 0. Personal communication. National Marine Fisheries Ser- vice, Galveston, Texas. 1980. Turner, R.E. Intertidal vegetation and commercial yields of penaeid shrimp. Trans. Am. Fish. Soc. 106:411-416; 1977. White, C.J. Perret, W.S. Short term effects of the Toledo Bend Proj- ect on Sabine Lake, Louisiana. Proc. of the 27th Annu. Conf. S.E. Ass'n of Game and Fish Comm. 1973; 710. Williamson, S.C. Penaeid shrimp abun- dance and riverine flow in San Antonio Bay, Texas. Proc. of the 31st Annu. Conf. Southeast Assoc, of Game Fish Comm. 1977; 522. Van Lopik, J.R. et al., Fishery man- agement plan for the Gulf of Mexico United States waters. Tampa, FL: Gulf of Mexico Fish- ery Management Council, 1980. 435 AN EVALUATION OF AQUATIC LIFE FOUND AT FOUR HYDRAULIC SCOUR SITES IN THE COLUMBIA RIVER ESTUARY SELECTED FOR POTENTIAL SEDIMENT DEPOSITION Joseph T. Durkin, Travis C. Coley, Keith Verner, and Robert L. Emmett National Marine Fisheries Service, Hammond Biological Field Station Coastal Zone & Estuarine Studies, Northwest and Alaska Fisheries Center Seattle, Washington ABSTRACT Substantial scouring of estua- rine sediment occurs from flushing of a major river system with an an- nual spring freshet of 20,300 m /s. The effect is heightened by diurnal marine water intrusion combined with spring tides having ranges exceeding 3 m. Estuary depth is maintained by these forces at the end of jet- ties, promontories, and adjacent bridge openings. Hydraulic stress in these areas suggests biological instability, a low standing crop and occupancy by species tolerant of such physical conditions. Be- cause inwater sediment disposal at sites with low biological activity is preferable to deposition at bio- logically rich and stable sites, scour sites were investigated for potential dredge deposition. Bio- logical inventories of aquatic life were conducted in October, November 1978 and May 1979, at four diverse scour sites in the Columbia River estuary, river km 4 to river km 24. Investigative timing was related to the completion and initiation of normal maintenance dredging. Benthic infauna, epifauna, and pelagic; fish were studied as well as food utilization of dominant fin- fish. The 71 sampling efforts pro- duced 42 species of finfish consist- ing of 31,870 individuals. Also captured in this sampling were 4 species of decapod crustaceans re- presenting 4,957 epifauna. Numer- ically important benthic inverte- brates included amphipods and cope- pods. Inventory studies indicated low suitability for sediment depo- sition due to biological richness at the Tongue Point and Interstate Bridge sites. Jetty A site was biologically poor, and has poten- tial suitability as a deposition site. Tansy Point site may be suitable for depositon at pre- determined times. Inventory eval- uation studies should be tested under controlled deposition condi- tions preceding sustained usage. INTRODUCTION High volume flows characterize the Columbia River, the Nation's second greatest river and the lar- gest flowing into the Pacific Ocean 436 from the Western hemisphere. High flows are particularly noticeable from late May to early July as snow melt runoff from several, mountain ranges averages 20,300 m /s. The effect is magnified by spring tides that exceed 3 m. Estuarine hydraulic forces combine to naturally deepen sites adjacent to jetties, peninsu- las, or bridge openings. Dredging is never required at these sites since navigation channel depths may be ex- ceeded by 3 m to 20 m. There is an annual removal of 3,000,000 m of sediments from the lower Columbia river estuary with most returned to the water. Es- tuarine sediment deposition can adversely impact many groups and species of aquatic life. Particle size change, smothering, and rein- troduction of toxic substances are several factors which can alter a natural biological system. The National Marine Fisheries Service (NMFS) is vitally interested in minimizing adverse impacts to eco- nomically important fish as well as food organisms they utilize. The Corps of Engineers (COE) is charg- ed with the responsibility of main- taining a 12-m deep, 180-m wide (40ft x 600ft) navigation channel for ocean shipping through the Columbia River estuary. The principal means of sediment removal to river km 32 is by hopper dredge which results in an inwater disposal. Sediment disposal of material dredged near the mouth is often placed in the ocean but several sites are utili- zed within the estuary. Concern over the continuing effect of dredge material on demersal finfish and shellfish by NMFS and COE sug- gested the agencies investigation of alternative sites. In an earlier NMFS study, Dur- kin (1975) indicated relatively few finfish and shellfish off the Colum- bia River's North Jetty, whereas comparable sampling at nearby sites revealed greater numbers of fish. These results seemed to indicate the water turbulence off the North Jetty caused biological instability resulting in a low standing crop of demersal organisms. This concept, when applied to an estuarine situ- ation, indicates use of similar ha- bitats for sediment deposition rather than continued use of exist- ing controversial inwater disposal sites . A biological inventory of sev- eral hydraulically dynamic sites by NMFS was proposed to the Portland District COE in order to determine if estuarine hydraulic scour sites normally had low biological stand- ing crop, were unstable, and sup- ported species tolerant of stress. The concept was accepted by the COE, and inventory sampling was scheduled for the conclusion and beginning period of normal hopper dredging activity. It was empha- sized by NMFS that should a site have apparent biological deficien- cies more intensive sampling would precede and follow any deposition test by COE hopper dredges. METHODS AND MATERIALS Four sites were selected for inventory studies, each near the navigation channel and in the lower 18 miles of the estuary (Figure 1). Sites were named after nearby land promontories or structures. Thirty pelagic finfish surveys were made with a 200-m purse seine whereas forty demersal finfish surveys were made with an 8-m shrimp trawl. Each sample effort was five minutes in duration. Purse seine and trawl sets 437 1 Jetty "A" 3 Interstate bridge j • ■ /ft N>> \ „ l'*' fflfi" . -_-^^ - ASIOBIA oatcON WASHINGTON SHIP CHAN --• - Trawl Tow O - Puru Seine Set o - Bonthic Invertebrate/ Sediment Core 2 Tansy Point 4 Tongue Point ?^ Jv "«»»"« .£^r Figure 1. — The Columbia River estuary with the sampling effort shown for the four hydraulic scour sites. 438 were made in an upstream or easterly direction but trawling was undertaken specifically during flood tide condi- tions. During the two survey peri- ods, October /November 1978 and May 1979, there were five trawJ sets and five purse seine hauls made at each site. An exception occurred at Jetty A where hazardous wave action and tidal currents prevented the purse seine effort. Finfish were identified to spe- cies, anesthetized, examined, mea- sured in millimeters and weighed in grams either' aboard the vessel or at the Hammond Laboratory. In each sam- ple up to 50 randomly selected indi- viduals of each species were selected for length/weight frequency measure- ment and up to ten were sacrificed for stomach content determination. Decapod crustaceans such as crab and shrimp were weighed and measured. Specimens retained for food- utilization studies were injected with Formalin (Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA.) into the stomach immediately after capture. The stomach was later removed between the esophagus and pyloric sphinct- er, contents placed in 70 percent alcohol and examined with a 10- power microscope. Food items were identified to the lowest possible taxon, air dried, and weighed to the nearest 0.0001 gm. Benthi c infauna, captured with a 0.05-m Ponar sampler, were wash- ed free ol sediments, retained on a 0.595-mm sieve, and fixed in a 10 percent Formalin-rose bengal stain solution. A series of 10 samples taken at each of four sites during both survey periods resulted in 80 samples. All inver- tebrates were identified, sorted into groups, counted and weighed. Similar groups were air dried for 10 minutes, weighed to the nearest 0.0001 gm and preserved in an al- cohol-glycerin solution. Sediment samples were gathered during each benthic invertebrate survey. Ten substrate samples were collected at each site during each survey, for a total of 80 samples. Temperatures and salinities were taken on the bottom and surface at each site and survey with a Beckman RS5-3 salinometer. Sediment samples were refrigerated and transferred to a private analytical laboratory for determination of particle texture components and total volatile solids. Particle-size categories followed the Wentworth scale described by Twenhofel and Tyler (1941) and were listed in percentage weight of the total sample. RESULTS FINFISH AND DECAPOD CRUSTACEAN EVALUATION The various species of fish and decapod shellfish captured during trawl and purse seine sam- pling are presented in Table 1 . The list includes 47 species with 37 appearing in trawl catches and 22 in purse seine catches. The fall 1978 trawling survey averaged 56.3 finfish and 78.5 shellfish per minute of sampling effort whereas the May 1979 survey yielded considerably less with an average 7.5 finfish and 34.7 shellfish for 439 TABLE 1.- -Finfish and decapod shellfish captured with purse seine and trawl nets during sampling at four hydraulic scour sites in the Columbia River estuary Oct. /Nov. 1978-Hay 1979 , FISH Pacific lamprey Spiny dog: . White sturgeon American shad ... herring rn anchovy Chum salmon Coho salmon Sockeye salmon Chinook salmon "0" Chinook salmon "I" Cutthroat trout Rainbow (steelhead) trout Wliitebait smelt Surf smelt Long Tin smelt Eulachon Peamouth -scale sucker Pacific tomcod Walleye pollock Three spine stickleback Bay pipefish Redtail surfperch Shiner perch ' in surfperch Snake prickleback Saddleback gunnel Pacific sand lance Vermi 11 ion rock fish Padde 1 sculpin Prickly sculpin Buffalo sculpin Pacific staghorn sculpin Warty poacher Prick lebr east poach.:- r Showy snailfish Pacific sanddab Speckled sanddab Butter sole En lish sole flounder Sand sole SCIENTIFIC NAME Entosphenus tridentatus Squalus acanthias Acipenser transmontanus Alosa sapidissima Clupea harengus pallasi Engraulis mordax Oncorhynchus keta Oncorhynchus kisutch Oncorhynchus nerka Oncorhynchus tshawytscha Oncorhynchus tshawytscha Salmo clarki Salmo gairdneri Allosmerus e Hvpomesus pret iosus Spirinchus thaleichthys Thaleichthys paeificus MsMocheiliis caurinus romus macrocheilus i igadus proximus TheraKfa cha 1 co^ramma Gasterosteus aculeatus Svn^nathus griseolineatus Amphistichus rhodo terns Cymatogaster aggregata ■ . . ! . . : . i:ia le Lumpenus sagit ca Pholis ornata Ammodytes hexapterus Sebastes miniatus Artedius fenestralis Cottus asper Enophrys bison Leptocottus armatus Occella verrucosa Stellerina xyosterna Li par is pulchellus Citharichthys sordidus Citharichthys stigmaeus Isopsetta isolepis Paropbrys vetulus Platichthys stellatus Psettichthys melanostictus Number 1978 Numb er 1979 Trawl P urse Seine Trawl Purse Seine Total _ 4 4 8 2 - - - 2 1 - 1 - 2 - 571 _ 156 727 2 ■ _ 228 17573 127 2183 29 16 2355 - - - 9 9 - 3 1 1473 1477 - - - 9 9 - 95 - 1151 1246 _ 6 - 450 456 _ - - 13 13 _ _ - 173 173 1 _ 5 - 6 - 190 - 898 1088 3719 4 2 314 40 39 - 1 - 3 4 - - - 32 32 - _ 5 2 7 497 - 275 2 774 _ _ 5 - 5 - 39 - 27 66 1 - - - 1 5 - - - 5 553 65 5 11 634 4 _ - - 4 18 .. S3 - 81 31 - 1 - 32 _ - 1 - i - _ 1 - 1 - _ 1 - 1 29 _ 26 - 55 1 _ _ - 1 315 1 166 1 483 1 - 3 - 4 5 - 25 - 30 - _ 21 - 21 1 _ - - 1 1 _ 4 - 5 6 _ 1 - 7 20 _ 20 - 40 255 6 81 13 355 33 _ 4 - 37 Sub Total 5628 20507 750 4985 31870 COMMON DECAPOD CRUS'I Sand shrimp Sand shrimp Sand shrimp Dungeness crab SCIENTIFIC NAME Crangon franciscorum Crangon s tyliros t ris Crangon nigromaculata Cancer magister Traul Purse Se ine Trawl Purse Total 1881 L69 7 161 0 n 0 0 2218 289 213 19 4118 458 7 374 Sub Total 2218 0 2720 19 4957 I OTA I 7846 20507 3470 5004 36827 440 each minute of effort. The purse seine effort in 1978 produced 274.8 finfish per minute of effort due to a large catch of Pacific herring at Tongue Point while the May 1979 sur- vey averaged 66.4 finfish per minute. Catch results indicated both sub- stantial numbers of finfish and spe- cies diversity at sample sites. Eco- nomically important species were com- mon and included coho salmon, Onco- rhynchus kisutch; chinook salmon, 0. tshawytscha ; starry flounder, Pla- tichthys stellatus ; American shad, Alosa sapidissima ; and Pacific her- ring, Clupea harengus pallasi . A summary of species and num- bers captured at each site is shown in Table 2. Grouped weights are included to provide further assess- ment of catch results. Purse seine catches at the Tongue point site had substantially more pelagic fish than other areas in October and May. Trawl catches revealed the Interstate Bridge site had the highest number of demersal finfish, but many were also found at Tongue Point. The Dungeness crab, Cancer magister , was abundant at Tansy Point. Overall, the catch results indicated Tongue Point had a high biological value in terms of fish and crustaceans. Several important finfish spe- cies captured in this study were ex- amined to determine if their sizes and food utilization were comparable between the sample sites. The five species, chinook salmon, Pacific her- ring, American shad, Pacific tomcod, Microgadus proximus , and Pacific staghorn sculpin, Leptocottus arma- tus, represent 66.7 percent of all finfish captured. Shad and herring represent pelagic species while chi- nook salmon occur in both pelagic and intertidal habitats, whereas tomcod and staghorn sculpin are demersal fish. Pacific herring populations consisted of at least two age groups in the October 1978 survey, with larger fish in the marine hab- itat and smaller fish at the fresh- water site (Figure 2). The modified Index of Relative Importance (IRI), described by Pinkas (1971), indi- cated herring were actively feeding on calanoid copepods , but only at Tongue Point. In the May 1979 survey, a single herring age group predominated at Tansy Point and the Interstate Bridge. Zooplankton was the principal diet though a substantial proportion of fish examined had not eaten. American shad were also repre- sented by two distinct age groups but they were present during both surveys (Figure 3) . It was evident the age groups had increased in length sev- eral centimeters between October and May. The IRI indicated the impor- tance of unidentified plant material consumed at the upper three sites during the fall survey. At Tongue Point where most shad were found, however, calanoid copepods were also an important food item. In May 1979, shad consumed the benthic amphipod Corophium salmonis and calanoid copepods at Tongue Point and Tansy Point. Copepods were the important identifiable food item at the Interstate Bridge where most shad were captured. Chinook salmon length fre- quency and IRI categories are shown in Figure 4. Only subyear- ling fall chinook were encountered in the 1978 survey with most taken at Tongue Point. Identifiable food items at that site were pri- marily insects. The May 1979 chi- nook catch consisted of subyearling fall chinook, yearling spring chinook and a few residuals. Diet of all the 441 c ir. £ l~l -C 01 ■— c c u a > re T3 HI - £ 3 0) to ~0 > c 0> 1- V- 4J oi a. o- o: x eft E- .c T3 < w o ;_> -h a v- J c o (U 3 -w a) ■8 2""= 4-> f- 01 0/ 6 e 3 3 a. re oc oc ■_ u 3 3 -C "O en o ■h a. i~ re c o •h ai < in (Si 0] 01 01 oi a. a c- ■a o D. 01 O 0) 01 V- V- ai a; S E .c 13 0} o 0) 0> u- re u-i re co c u •h ai -h (u * * a) a vi 0) ^ Cfi 0) (U v- u 4_> 4-1 ■H •H 0) u> j= .c CJ a> ■fl ■fi oc oc — | — < r. a 3 3 0) 01 U- m CA C C 3 3 Z T3 j: -a .c -a bJ cr O en o oi o rn ■H a ■H 0- ■H O. ^ tfl l*- 10 u* re >-. U c u c o c u a> (/> 0) •H ID •H 01 :r. U- a U-, fj u. o o ^ i-> a- i < a> 0) 01 0! 01 0) 01 til \- M 4-1 4-1 •r-4 (ii 01 £ J 01 •i i OC '-4 O. a 3 3 0) 01 01 yi C C 3 3 c -o x: T3 -C 13 UJ oi o 01 () 01 0 ai •H o. •H a ■H p. 14— 01 U-t re >4- re U C o c u c u t/l -H 01 •H o> L 02 U. a u. o u. a 3 >>o. 442 PACJ'JC MURING DO l°78 Po.,,1 I Inter stats Bridge Tongue ,0| Po.nt 5o[ Tan, , Po.nl Inter s tale Bridge Tongue Po.nt n» IftJs^.w- kSf n-68 10 12 If 16 18 20 22 24 FORK IF.NGTH IN cm PERCENT J C D U Z T n: 5 5 Empty CAIANOID COPEPODS r n: 10 6 Empty cladocera unidentified copepods digested material 100 0 100 Jta n :48 3 Empty 0 TJT-n n=22 14 Empty 100 n:24 10 Empty 100 LlI PERCENT F.a Figure 2. Length frequency and food habits of Pacific herring captured at four estuarine hydraulic scour sites during two surveys. The IRI diagram for this and the following four figures shows numerical percent of food organisms above the horizontal line, the percent weight below the horizontal line, and width of the box represents the percent frequency of occurrence of the item in stomachs (see enlarged diagram below) . Index of Relative Importance (IRI) numerical value determination (N + W)F = IRI. 100 50 50 tool 0 PERCENT NUMBER PERCENT WEIGHT 50 100 PERCENT FREQUENC, OF OCCURRENCE 443 WWtKKAW >H»» OCT. 1978 T«nty Intor ■ tat* Bridgo n=5 oL •«a . 9 n:9 3 A . - it. IK' • KU :9 1 Empty A-COIOPHrUM SAIMONIS C CAl>NOlD COtl^OM N NEOMTSIS AftCEOlS U UNIDENTIFIED COfi'ODi X-PlANT MATERIAL T FISH SCALE* I DIGESTED MATERIAL 0:43 4 Empty MAY 1979 1 Jatly A laniy Point qL. jf a pa/nip n . (I n=27 * • rat* 5 ■ ridg* oL id»^-M^ . n = 115 ■ .n^ifS^.tVi To n g 11 • F»int 0L ._ 10 12 14 16 18 20 22 24 26 28 30 FORK LENGTH IN cm m n:ll 3 Empty PUCINl F.O Figure 3. Lengths and food use of American shad captured during two surveys at four Columbia River estuarine sites. OCT 1978 t CHINOOK SALMON Tom, 51 Point u^ stole - Bndg. 0 n:J 1 Empty - - - longu. ,0T Pent 5; 1 = 72 A COROPHIUM SAIMONIS B ANISOGAMMARUS CONFER VICOLUI G ClRRIPEDIA H HOMOPTERA K DIPTERA M CORIXtOAE O HYMENOPTERA Z DIGESTED MATERIAL MAY 1979, Jotty ■ H- n:34 1 Empty 6 8 10 12 14 16 18 20 'Oil LENGTH IN cm PIICENT I. o Figure 4. Lengths and food use of chinook salmon. 444 young salmon was consistently the benthic amphipod, C. salmonis , at the three sites. Diptera was the other identifiable food item. stream sites indicating higher avail- ability of prey organisms in that area . Pacific tomcod length frequen- cy and IRI categories are shown in Figure 5. Most of the 1978 fish fall into two age groups though a smaller size group appears at Jetty A and a few larger fish at the In- terstate Bridge. Prey items varied considerably between the four sites. The IRI indicated anchovy, amphi- pods , mysids, and crangon shrimp were all extensively utilized. The 1979 survey indicated tomcod were present at the two marine sta- tions, but only one age group was represented. Benthic amphipods and mysids were numerically important food items, whereas digested fish and crangon shrimp accounted for most of the weight. The demersal Pacific staghorn sculpin size group and food utili- zation is shown in Figure 6. Inter- gradation of sculpin length obscured any size grouping during both sur- veys though the larger sculpin were found off Tongue Point in October and at Tansy Point in May. Epiben- thic fauna diversity typified the diet of sculpin caught in October. Benthic amphipods, C. salmonis and Anisogammarus confervicolus , and fish were the essential diet items of sculpin in May. Dietary organisms for the fish varied dramatically during the Oct- ober survey depending upon species and where they were caught. The May survey results indicated a smaller selection of food items and substantial use of both calanoid copepods and benthic amphipods. The incidence of empty stomachs was some- what less in the fish captured at up- Particle size ranged from medi- um gravel (8mm) down to clay (0.00 to 2mm). The proportional average value of ten samples for each site was de- termined and plotted by size cate- gory (Figure 7). The unbroken lines indicate results from the fall 1978 survey, while the dotted lines re- present results from May 1979. Sev- eral characteristics were noted. (1) Medium grain sand (0.25-0. 5mm) was the major size category of sedi- ments at all sites. (2) The high proportion of medium grain sand was unchanged at all sites between the two surveys. (3) Slightly higher proportions of both larger and finer sediments were found at sites above Jetty A. (4) The scour sites are essentially homogeneous substrate habitats with little evidence of sediment accumulation or seasonal change. Total volatile solids (TVS) were analyzed in each sediment core with the range and average for each site and survey shown in Figure 7. The sediment was essentially clean sand with average levels of two per- cent or less, though two samples exceeded the EPA six percent level. Averages of two water quality parameters (salinity and temperature) gathered with sediment and benthic infauna samples also appear in Fig- ure 7. The values are represented from readings taken at the surface (S) or bottom (B) . The salinity levels ranged from marine to fresh from Jetty A to Tongue Point, and from bottom to surface. Salinities change dramatically with season and 445 OCT. 1978' l«lly 51 r 1 Janty 1 Point Jtr __, ■tt. t^r^:' ■ , I [-^Xt^ <1 tnT«r Bridg.^ Tonqual . «>oint oL 6 8 10 12 14 16 18 20 22 24 26 28 FORK LENGTH IN X ll I Z >• o- u> tt tf» 0 o 5 _• ■ " 2 o mil °l < CO m O X 0 t I: IN #--r 2 3 _ i j o -^ 1— 2 — 2-J 6I u 3 4-1 CO 01 01 > •H Pi ,0 e 3 rH O U 0) 4-1 a •H to oi 4-1 •H 05 i-l 3 O O to Vj 3 O 14-1 to > 3 to s >. w 0 o 1 os c 0) C O -t(N •H *" 3 lli T3 • I CO * C : io 0 •H 4-1 L° •0 ■H e .o 0 *■ O in — — o H |i = -«n (N Cfl o 1 : : O •H v» ta */» «a to 5 o « s- >~. o » X. ° 1 s p-> C Ol E*& 0 £~ |f §5 * o.<* 0 1-1 3 SO ■H 447 water volume, however, in this study they were generally comparable at the time of the October and May surveys. Water temperatures were similar from surface to bottom through both sur- veys. Depths at sample sites were greater during the May survey and may reflect fresher runoff conditions . and Durkin and Emmett (1980). How- ever, scour area invertebrate densi- ties were considerably lower than those found in nearby estuarine em- bayments by these same investigators. CONCLUSIONS BENTHIC INVERTEBRATES Taxonomic groups and species captured in the 80 October and May samples are listed in Table 3. In- cluded are the sites and surveys where they occurred. There were 43 groups or species listed with the highest diversity found at Tansy Point and the Interstate Bridge. Some epibenthic invertebrates spe- cies were captured with the infau- na grab-sampler and others with the trawl. Epifauna include the bivalues Corbicula manilensis and Mytilus edulis , several species of mysids, crangon shrimp, Dungeness crab, cope- pods, cladocerans and Trichoptera. Comparative abundance of ben- thic invertebrates is shown for the four sites and two survey periods in Table 4. The density of infauna organisms was low at all sites in October although copepod epifauna at the Interstate Bridge provided an appearance of numerical impor- tance. The May survey results re- vealed greater infauna densities at all four sites. Increases occurred in nearly all groups, but particu- larly the Amphipoda, Nematoda, and Copepoda . Jhe densities of organ- isms per m were greater than pre- viously reported in estuarine sam- pling studies at or near the navi- gation channel by Sanborn (1973, 1975), Higley and Holton (1975, 1978) Hydraulic forces which maintain water depths at the four study sites apparently result in a uniform sub- strate which accumulates little sedi- mentary material. Benthic infauna densities increased substantially between surveys though there was no obvious change in sediment particle size. Some of the sites appear to have substantial numbers of pelagic schooling fish, demersal fish and shellfish. Fish examined for food utilization consumed other fish, zoo- plankton, insects, a variety of epi- fauna, and benthic amphipods . The amphipod most frequently consumed, C. salmonis, is an infauna tube-dwelling species that apparently migrates into the water column because it was con- sumed by both pelagic and demersal fish. On the basis of the inventory, the Jetty A site would be suggested as a test disposal site particularly in October and November, whereas Tongue Point would be excluded from further consideration. The Inter- state Bridge site, though not as valuable as Tongue Point, should also be excluded from a test disposal effort. Tansy Point may have po- tential as a test disposal site though further evaluation is needed, particularly during the active dredg- ing season. A test disposal program should provide for an evaluation of fisheries and infauna by preliminary and post disposal sampling. The 448 TABLE 3.--Benthic invertebrate and epifauna collected October-November 1978, and May 1979 at four scour sites in the Columbia River estuary. Jetty A Tansy Point Interstate Bridge Tongue Point 1, 2 1, 2 1, 2 alb I Phylum Ctenophora 1 ,-*2 J Phylum Platyhelminthes Class Turbellaria 2 Phylum Nemertea 1,2 1, 2 Phylum Acanthocephala Phylum Nematoda 1, 2 1,2 Phylum Annelida Class Polychaeta Family Nephtyidae Nephtys californiensis 1 , 2 Family Nereidae Neanthes limnicola 2 Family Orbiniidae Haploscoloplos spp. 1, 2 Family Phyllococidae Eteone dilatea 2 Family Spionidae Polydora spp. 1 Spio f ilicornis 2 1 Family Capitellidae Capitella capitata 1 Class Oligochaeta 2 1 1, Phylum Mollusca Class Gastropoda 2 Class Bivalvia Family Corbiculidae Corbicula manilensis 1 Family Tellinidae Macoma balthica 1 , 2 Family Mytilidae Mytilus edulis 1, 2 2 Phylum Arthropoda Subphylum Mandibulata Class Crustacea Subclass Branchiopoda Order Cladocera 12 2 Subclass Copepoda 1, 2 1, 2 1, 2 Subclass Cirripedia Family Balanidae Balanus crenatus 2 aj Collected in October-November 1978 bj Collected in May 1979 2 1, 2 1, 2 1, 2 2 1, 2 1, 2 1, 2 1, 2 449 Table 3. — (Cont.) Subclass Malacostraca Superorder Peracarlda Order Mysidacea Family Mysldae Archaeomysis grebnitzkii Neomysls mercedis Acanthomysls macropsls Neomvsis kadiakensis Order Cutrtacea Family Diasiylidae Diastylopsis dawsoni Family Leuconidae Hemileucon comes Order Isopoda Suborder Flabellifera Family Sphaeromatidae Gnorimosphaeroma oregonensis Suborder Valifera Family Idoteidae Mesidotea (=Saduria) entomon Idotea f ewkesi Order Amphipoda Suborder Gammaridea Family Corophiidae Corophium salmonis Corophium spinicorne Family Gammaridae Anisogammarus conf ervicolus Family Haustoriidae Eohaustorius estuarius Family Oedicerotidae Monoculodes spinipes Family Phoxocephalidae Paraphoxus milleri Superorder Eucarida Order Decapoda Suborder Natantia Family Crangonidae Crangon f ranciscorum Crangon stylirost ris Suborder Reptantia Cancer magister Class Insecta Order Diptera Family Chironomidae Family Heleidae Order Trichoptera Order Hymenoptera Jetty Tansy A Point 1, 2 1. 2 Trawl Trawl Phylum Chaetognatha 1 1, 2 1, 2 Trawl Trawl Trawl Interstate Tongue Bridge Point 1 9 1 2 1, 2 1 J Trawl-* 2 1, 2 Trawl 2 Trawl Trawl Trawl 1, 2 1, 2 Trawl 1, 1 2 2 2 1, 2 1, 2 1, 2 1, 2 2 1, 2 1, 2 cj Species captured with 8 m shrin 450 XI oi X a HI 1-1 CO 3 en cr X O) 0 •H Ij u oi cu 4-1 ft 0) E >^ oi M > 0) 1-1 ft 3 01 0) Vj o CD 13 XI 4-1 ti 3 01) C c •H C u •H 3 XI 01 oi 01 4-1 14-1 c 4-1 CO c dl (11 -D 4-1 CO UJ O 0) cu (fl r-U Cl ft 3 t" o rt p en 01 j- (fl co 3 u 0 on ■H 1- CN (0 e > in 14-1 o o • o CD O u c CO CO c TI o c ft 3 J3 c < 1 r-H w ►J > 4-1 01 C C -H CO O H ft 4-1 < 0) 0) 4J P d OO-H c o o cu H 0) 4-1 CO 0) 4-1 00 oi x 01 lu 4-1 PQ c ^ 4J 01 C CO o H Cu 4-1 < Cu D o « O 00 00 O Cl ■j m m (M \o O ft nl . . -H ft -H X >,O0o)4-ic0OIUt-I i— I -H 3 (9 > h 1< n O i— I ■— I CO -H J3 -H >> CuOi-lOcQ4-iU2 O U X < CO CO X CO O X ft o •H ft O _ CO X CO ft X E ft cj o co CO l-i CO 01 XI CJ O O ft CO 01 4-1 ft 3 E 01 01 .-H O CJ < O l-i u o 0) CO CO i- U 01 01 4-1 4-1 ft ft 0 o C J3 01 cj E v-l 1-1 >, l-i 01 a: H .c n 01 cn 4J CO I- 01 > 0 r l-i XJ or CO ft r. rH o 4J c ",/ J= 01 CO 01 _l 4-1 J3 •H < CJ CJ CU o H 00 >£1 00 r- 1 CN O O 00 O o CN CO fl 451 Corps of Engineers should also moni- tor sediment particle movement from the test site to determine its fate. It is recommended that riverine and oceanic sites with hydraulic scouring be evaluated biologically to deter- mine why some areas are rich in spe- cies and others are not. ACKNOWLEDGEMENTS the Columbia River estuary. NMFS. Coastal Zone and Estuarine Studies. 1980; 44p. Higley, D.L.; Holton, R.L. Bio- logical baseline data Youngs Bay, Oregon. Final Report 1 November 1973 through 30 April 1975. Corvallis, Oregon: School of Oceanography, Oregon State University, 1975; 75-6p. This study was conducted with contractual assistance from the Portland District, U.S. Army Corps of Engineers, DACW 57-79-F-9145 . We appreciate the cooperation and assistance of Jack Bechley, Navi- gation Division. Roy Pettit, Nick Zorich, and David Miller contributed essential effort in the studies data gathering phase while Sandy J. Lippovsky assisted with laboratory analysis of stomach contents. Imo- gene Abrahamson typed the manuscript and Jim Peacock prepared plates for the figures. We are indebted to these and other staff personnel in Hammond, and Prescott, Oregon and Seattle, Washington who supported this effort. REFERENCES Higley, D.L.; Holton, R.L. A grab- sample study of the benthic in- vertebrates of the Columbia Riv- er estuary. Supplemental data Rep. 1 November 1975 through 29 February 1976. Port of Astoria. 1978; 76-3p. Pinkas, L. ; Oliphant, M.S.; Iver- son, I.L. Food habits of al- bacore, bluefin tuna, and boni- to in California waters. Cali- fornia waters. Calif. Dept. Fish and Game; Fish Bull. 1971; 105p. Sanborn, H.R. Benthic infauna ob- served at five sites in the Columbia River from August 19 73 to July 1974, Nat. Mar. Fish. Ser. Final Rep. to U.S. Army Corps of Engineers and Col. Riv. Prog. Off. ; 1973; 19p. Durkin, J.T. An investigation of fish and decapod shellfish found at four dredge disposal sites adjacent to the mouth of the Columbia River. Report to Portland District Corps of En- gineers and NMFS Columbia Riv- er Program Office; 1975; 29p. Durkin, J.T.; Emmett, R.L. Benthic invertebrates, water quality and substrate texture in Baker Bay, Youngs Bay and adjacent areas of Sanborn, H.R. An investigation of the benthic infauna at two dredge and four dredge dispo- sal sites adjacent to the mouth of the Columbia River. Nat. Mar. Fish. Ser. Final Rep. U.S. Army Corps of Eng. and Col. Riv. Prog. Off; 1975; 15p. Twenhofel, W.M. ; Tyler, S.A. Meth- ods of study of sediments. New York: McGraw-Hill Book Co.; 1941. 452 CHAPTER 7 FRESHWATER INFLOW STUDIES IN SOUTHERN TEXAS ESTUARIES 453 THE EFFECTS OF FRESHWATER INFLOW ON SALINITY AND ZOOPLANKTON POPULATIONS AT FOUR STATIONS IN THE NUECES-CORPUS CHRISTI AND COPANO-ARANSAS BAY SYSTEMS, TEXAS FROM OCTOBER 1972 - MAY 1975 Richard D. Kalke University of Texas Marine Science Institute Port Aransas Marine Laboratory Port Aransas, Texas ABSTRACT Between October 1972 and May 1975, two periods of major freshwater inflow (June-November 1973 and August and September 1974) affected zoo- plankton populations in the Nueces- Corpus Christi and Copano-Aransas Bay Systems. Inflows resulted in re- placement of estuarine species with freshwater species and the lowering of salinities to near 0 parts per thousand (ppt) . Populations of the calanoid copepod, Acartia tonsa, were lowest during maximum inflow but sharply increased following salinity increases as small as 1 to 3 ppt. INTRODUCTION During the period October 1972 through May 1975 the Texas Water De- velopment Board and the City of Cor- pus Christi funded a project to moni- tor the effect of freshwater inflow on the phytoplankton, zooplankton, and benthic communities in the Nueces-Corpus Christi and Copano- Aransas Bay Systems. Increased muni- cipal, agricultural, and industrial usage of fresh water prompted the need for research in determining re- quirements of freshwater inflow into Texas estuaries. The study area was located with- in the south central climatological division (Texas Water Development Board 1968) between 27°40' and 28°10' north latitudes and 96°50' and 97°30' west longitudes. The average annual precipitation in this climatological division was 84.4 cm. Aransas Bay, composed of Copano , Aransas, Redfish, St. Charles and Carlos bays, has about 5.7x10 ha and has an average of 81.3 cm annual rainfall (Texas Water Development Board 1968). Aransas Bay, histori- cally, has received about 7.3x10 m of fresh water annually. Physical characteristics of the Aransas Bay system, i.e. water circulation, drainage, and oyster reef distribu- tion, are given by Parker (1959) and Gunter (1945). According to Gunter minimal amounts of water, if any, from the Nueces-Corpus Christi Bay intrude into the Aransas Bay system. Collier and Hedgpeth (1950) give a detailed analysis of the hy- drography of the study area. The Corpus Christi Bay system is composed of Nueces, Oso, and Corpus i >-4 Christi bays which total about 5 . 4x 10 ha (Texas Water Development Board 1968). The average rainfall for this area is 76.2 cm annually. This bay, historically receives ap- proximately 1.23x10 m of fresh wa- ter annually. Descriptive studies of the Corpus Christi Bay system include Hood (1952) and Anderson (1980). Thirty sample sites were estab- lished in such a pattern as to give the broadest possible coverage of the different areas and physical para- meters (Figure 1). Although 30 sta- tions were established only four were located in close proximity to major sources of freshwater inflow and these sites were selected to monitor freshwater inflow effects on zoo- plankton communities. Station 38-2 was located at the mouth of the Nue- ces River. Station 200-2 was at the entrance of Oso Bay. In Copano Bay, Station 44-2 was near the mouth of the Aransas River and Chiltipin Creek. Station 54-3 was at the en- trance of Mission Bay. MATERIALS AND METHODS Zooplankton samples were col- lected with a 0.5-m #10 mesh (153 u) nylon net. One-minute surface tows were made in a counterclockwise di- rection from the port side of the boat so that the net was towed clear of the boat's wake and wheelwash. The amount of water filtered was mea- sured with a General Oceanic Model 2030 digital flowmeter attached in the center of the mouth of the net. Samples were preserved with 5 percent buffered Formalin. In the laboratory, plankton sam- ples were subsampled using a Hensen- Stemple pipette. Counts were made using a Wild M-5 dissecting micro- scope. Standing crops were express- ed as total numbers of individuals per cubic meter (m ) . Local rainfall data, which were collected at the Corpus Christi In- ternational Airport were obtained from summaries of annual rainfall for this area (United States Department of Commerce 1972, 1973, 1974, 1975). Total inches of rainfall for the 10- day period prior to and including the collecting date, were used for linear correlations with salinity data. Streamflow data were obtained from the Texas Natural Resources In- formation System in Austin, Texas for the following gaging stations :0821- 1000, Nueces River near Mathis, Tex- as; 08211520, Oso Creek at Corpus Christi, Texas; 08189700, Aransas River near Skidmore, Texas; 08189- 800, Chiltipin Creek at Sinton, Tex- as; and 08189500, Mission River at Refugio, Texas. These were the most downstream gaging stations nearest the sampling sites. Streamflow was measured in cubic feet/second (cfs). Total inflow for a 10-day period, prior to and including the date of data collection, were used for linear correlations. All linear correla- tions between streamflow and zoo- plankton standing crops were calcu- lated using raw data. The critical level for rejection of signifi- cance for a linear correlation was p = 0.05. Water temperature, dissolved ox- ygen, conductivity, and salinity were measured at each station. Salinity was the only hydrographic data used for analysis in this presentation. RESULTS The highest recorded rainfall from October 1972 to May 1975 for 455 456 the 10-day pre-collection period was 21.6 cm recorded in June 1973 (Fig- ure 2). Lower peaks of 13.2 and 19.3 cm were recorded in September and October 1972, respectively. In June 1974, 6.1 cm of rain occurred and in September 1974, 8.1 cm of rain were recorded. Salinity ranges and means for each station were: Station 38-2, 0.2- 31.6 ppt, x= 12.8 ppt; Station 200-2, 0.2-35.2 ppt, x = 24_^4 ppt; Station 44-2, 0.0-18.3 ppt, x = 7.7 ppt; Station 54.3, 0.1-17.1 ppt, X = 7.9 ppt. Salinity was negatively correlated with local rainfall at Stations 38-2, 200-2, 44-2, and 54-3 (r = -0.45, -0.73, -0.53, and -0.51, respectively, p£ 0.01). Streamflow and salinity patterns for Stations 38-2 and 200-2 are given in Figure 3. Streamflow for the Nue- ces River (Station 38-2) had its first major increase in June 1973 to 23,960 cfs (670.9 m /sec), followed by a decrease to 6,007 cfs (168.2m / sec) in July and 4,596 cfs (128.7 m /sec) in September. The highest inflow for Station 38.2 was 99,930 cfs (2798.0 m /sec) which occurred in October 1973. The salinity de- creased to 3.6 ppt in June 1973 and reached a low of 0.4 ppt in October and November 1973. Although the in- flow decreased to 2,868 cfs (80.3 m /sec) in December 1973 the salin- ity was still low at 1.3 ppt. An- other influx of fresh water was re- corded on the Nueces River in August and September 1974 (28,471 cfs (^97.2 ni /sec) and 64,210 cfs (1797.9 m /sec), respectively. For August 1974 salinity decreased to 0.4 ppt and in September 1974 salinity was 0.2 ppt. Streamflow had a negative correlation with salinity for Station 38-2 (r = -0.47, p < 0.005). In June 1973 the inflow for Oso Creek (Station 2QO-2) increased to 2,944 cfs (82.4 m /sec) with a cor- responding decrease in salinity to 8.2 ppt. (Figure 3). Streamflow dropped in July and August to 134 cfs (3.8 m /sec) and 92 cfs (2.6 m /sec) , respectively, and salinity increased to 23.3 ppt and 24.2 ppt, respec- tively. Major inflows of 5,511 cfs (154.3 m /sec) with corresponding sa- linities of 0.2 ppt and 3.6 ppt, oc- curred in September and October 1973. Although flow increased in June and September 1974 to 905 cfs (25.3 m /sec) and 304 cfs (8.3 m /sec), respectively, no decrease in salinity was measured. Streamflow was nega- tively correlated with salinity at Station 200-2 (r = -0.77, p 10.005). The Aransas River-Chiltipin Creek drainage (Station 44-2) and the Mission River (Station 54.3) had inflow and salinity patterns similar to each other (Figure 4) . Major streamflow increases occurred from June through October 1973, in May and June 1974, and in September 1974. Both Station 44-2 (r = -0.50, p £0.005) and Station 54.3 (r = -0.49, p £0.005) had negative corre- lations between streamflow and sali- nity. To determine effects of fresh- water inflow on zooplankton popula- tions, species were first catego- rized to be estuarine or freshwater species. A list of the dominant zoo- plankton is given in Table 1. Those species with an asterisk are con- sidered to be freshwater organisms. The effect of streamflow on standing crops (total number of in- dividuals/m ) of estuarine and fresh- water zooplankton at Station 38-2 is shown in Figure 5. Standing crops of 457 Table 1. List of Dominant Estuarine and Freshwater Zooplankton Phylum Protozoa Class Mastigophora Order Dinoflagellata Noctiluaa saintillans Phylum Rotifera Phylum Annel ida Class Polychaeta Phylum Mollusca Class Gastropoda Class Pelecypoda Rotifera sp. A Braahionus plioatilis Brachionus quadradentata* Lecane sp.* Platyias quadricornis* Polychaete larvae Gastropod larvae Pelecypod larvae Phylum Arthropoda Class Crustacea Order Diplostraca Cladocerans (immature)* Family Sididae Diaphano soma sp.* Family Daphnidae Ceriodaphnia sp.* Daphnia sp. * Moina sp. * Simocephalus sp.* Family Bosminidae Bosmina sp.* Family Macrothricidae Illyocvytis spinifer Macro thrix sp.* Order Calanoida Family Diaptomidae Diaptomus sp.* Pseudodiaptomus aoronatus Family Paracalanidae Paracalanus crassirostris 458 Table 1 Cont.'d Family Pontellidae Labidoaera aestiva Family Acartiidae Acartia tonsa Family Unidentified Copepod nauplii Order Harpacticoida Family Laophontidae Onychocamptus mohammed* Family Cletedidae Cletocamptus albuquerquensis* Cletocamptus dietersi* Order Cyclopoida Family Oithonidae Oithona spp. Family Cyclopidae Cyclopoid copepodids* Cyclops sp.* Eucyclops agilis* Eucyclops speratus* Macrocy clops albidus* Mesocyclops edax* Microcyclops sp.* *Denotes freshwater species 459 1 1 1 1 1 1 1 1 1 1 1 1 1 m i o o o i i i i 1 L i ~ o «■ . n C > v:: S»S N0U»1S 2->» NOIITIS ; 002 NOUTiS — •% AilNIIVS rst Nouvis TiVdNiva "WDcn jo sbhoni O U nj «3 00 CI •H •a 3 u a •H C o •r-l D< "C o a ex « ■a i o u o a •H « S-l i—l (0 U o i— i T3 C «J LO r-~ C c^ o »~* • 1-t J-) £* nj (15 J-> 2 w >^ XI Ovl r^ >i cr\ 4-1 — •i-i c )-i •r-t u - CSl ^ c > s c^ s-i 01 X> o 4-> U o I O o CM a i 00 co e o 4-> to o o S-l 4-1 •H (3 A3 to d (8 3 o s 0) S-l 4-1 GO CO 01 S-l a oo 461 C%) AilNHVS rX) A1INTTVS M3AIM NOISSM C-M NOI1V1S ( -M| *t»3t) 01 X SW/jW «0-UMV3)Ut X33MD NldiniMD M3AIM SVSNVMT ^-►fr N0I1V1S 2 U 0) o 4-1 u o CO I m -o c 03 CM I > 4-> ■H a (0 c to 3 o E 19 01 ttJ S-l 3 00 462 (°'6oi i|03i> ooi x 3»«/ji McndHvaais (0160| *|03«) 01 X dOUO 9NI0NV1S NOlXNVldOOZ 831VMHS3MJ Z-OT (°»0| »|03») 0001 X dOtO 9NI0NV1S NOlXNVldOOZ 3Nia»niS3 N0I1V18 s o I— I 4-1 s eo m M a 0) a •v •H > •H T3 C •H ^H <« J-" o 4-> ^~^ a o i-i u 00 a •H TJ d n) 4-> M • LO CJ r-~ o ON 4-> r-l M a >» m <0 t— i a a. o i o N CN r^ Sj o-> 0) r— 1 4-1 4J to (Z> W u c m in Ul •) 0001 X dONO 9NI0NV1S NOlXNVIdOOZ U31VMHS3Md NOlMNVIdOOZ 3NIUWUS3 Z-OOZ N0I1V1S o I— I 4-1 s ffj 1) n 4-> OQ TJ CI e to rH S3 T3 C O a, o u u a •H X) CI IT) s CI o 4-> CI 03 a, eg o r- o o^ N '-' !-l U ,fi <9 O 4.) u 3 J= w O OJ *-" - «" eg i "O O a o a) CM 3 4-> 4-) CO 14 3 0) 465 ( 6o| •lOtt) 01 X '••/,*» M01 JNV3M1S o s 0) S-l 4J w C m fO (°»©| UMB) 01 X dOMO WHONVIS (°»«>l»»»»000IX 4MO 8MWNV1S NOlMNVIdOOZ «31*»HS3«J NODDnridOOZ 3MMVIUS3 Z-»fr NOUV1S 3 TJ ■H > •H T> C •H ^H «5 *• 4-1 s O n 4-1 W G, O S-i U oo e •H T3 C >> -* 0) c s M —i i Q. s" i* n as N r— 1 £ 1-1 <" u ^ -l 4-1 • A3 « 3 4-> 4-1 CO W w ^ O 4-4 f- CIO OJ 01 i—l Sj -h 3 <4-l oc o •H !-4 b a 466 (°60| Host) 001 X 3»«/t»» M0tdHV3»US S „ ( c'»0| »|09«) 01 X dOMO 0NI0NV1S NOiXNVldOOZ U31VMHS3dJ (0l6o| viom) 0001 X dOMD ONWNViS NOiXNVldOOZ 3NIM*fllS3 o I— I 4-1 E CO 0) S-l a CO s w i— i CO 3 ■H > •H C •H CO 4-> o 4-) w Oh O u u 60 c •H c CO 4-1 . r- c^ a o 4-1 a CO iH a. o o N U U O CD C •H 1-1 CO 3 4-> W C-Vfi NOIlViS 00 w CJ (9 (J O i—l — 1 % H w >1 n rH ca •H 0) 4-> S-l « 3 •rH M u ■r) -C In CJ 474 0) >> -o X1 J3 O 4-1 O ^r r— 1 tn 0i 4-1 4-1 4-1 u o XI ■H 01 u a !-M •H 01 4-1 XI T3 «S 3 i — i 01 s^ XI oo 0) n! a a o o S-l N 4-1 XI It) X 4-1 4-1 0) a 01 o en > •H <0 01 4-> 01 .—1 a) 1-1 "0 nj 01 C X! a 10 4-1 a 3 ■H o 4-1 x o i— 1 (A « w T3 CN 01 •H S-l 4-1 01 «J 4-1 O a o Oi N XI 4-> tn QJ ^3 o C 4-1 « a N 01 a to 00 o 01 (3 •H S-l •H +J ft s « 01 o ^3 S-l X a tn to a en 3 a 0) o XI ■H a rH en •r-l 4_| S-l i-H ^H « C8 S-l £ TJ -O 01 •H 01 > tn 4-) 4-1 -i-l 0) 4-> S-l u O o 01 4-1 Q X a oo a 01 •H . X 0) xi Xi tn oi oo 4-1 4-> -o a 4-1 01 •H -H 4-1 H o CJ 3 to x -o a. a oo _. «j to ■h -a XI 0) 4-1 in o ly h mars oo u i—i e 01 S x) 10 S-l M «J o. I! 5 a < E 01 <» a •H ■a x a tn *J (0 tn oo a a CN 4-1 0) O i-f tn S-l ■o s-i 3 (0 O 0) oo 01 O 4-1 •H S-l — 1 to Pn M ■H J. 475 Mexico were obtained from the Na- tional Weather Service prior to sam- pling and then adjusted to compensate for the distance between the marsh and the gulf. In an effort to con- solidate the data for analysis the mean and slack tides for each tide cycle were combined. These events were then designated as flood and ebb tides. Exchanges of water between the Nueces deltaic marsh and bay were estimated by determining flow rates past a sampling station. A mea- sured distance of 100 ft (30.5 m) was laid out along the bank of the Rincon Bayou near its mouth. A weighted (partially submerged) float was then released in midstream and allowed to move with tidal flows. Elapsed time between start and finish yielded the flow rate in m/sec. To determine flow volumes, a cross-sectional map of the bayou was made using a sound- ing line and tide staff gauge (Figure 3). Individual measurements of velo- city were multiplied by the cross- sectional area represented by each respective sampling point to estimate volumes of flow. Velocity measure- ments were replicated to ensure reli- ability. ANALYTICAL METHODS AND EXCHANGE OF MATERIALS Total organic carbon and inor- ganic carbon measurements were made using a Dohrmann Model DC-50 organic carbon analyzer modified to measure inorganic carbon. Particulate orga- nic carbon was determined using the method described by Menzel and Vac- caro (1964) and the Dohrmann DC-50 organic carbon analyzer. Total phos- phorus and ortho-phosphorus concen- trations were determined using the oxidative and spectrophometric meth- ods outlined in Standard Methods (APHA 1975). Nitrate, nitrite, and organic nitrogen forms were deter- mined using methods outlined in Strickland and Parsons (1965) and Standard Methods (APHA 1975). A Beckman Model 25 UV-Vis Spectrophoto- meter was used in the final analysis of nitrogen and phosphorus forms. Ammonia concentrations were deter- mined using and Orion ammonia probe and Model 901 Orion microprocessor. The detection limits , of the probe ranged from 0.02 x 10 to 1.7 x 10 mg/1 free ammonia. Exchanges of materials on each sampling date were calculated by mul- tiplying the mean concentrations of replicate samples by the estimated flow volume for each tide stage in a 24-hour tidal cycle. Total exchanges of nutrients between the marsh and the estuary were determined from the difference in quantities of materials entering (flood tides) and leaving (ebb tides) the Rincon Bayou. RESULTS Flows in and out of the marsh are for the most part attributable to tidal action, and to a lesser ex- tent wind seiche. Flow rates varied seasonally with highest rates occur- ring in the spring (8.61 m /sec in April flood tide) and the lowest oc- curring in the late fall (0.59 m / sec in November flood tide). During the course of the study no major wea- ther events such as hurricanes or sustained flooding occurred. Spills from the Nueces River into the upper marsh occurred only once during the study period. This event was a brief spill, which was dispersed by evapo- ration and flows down tidal channels through the marsh to Nueces Bay. Low- er marsh inundation (Figure 2) oc- curred daily during most of April and May when tides were at their peak. 476 CO 3 o c o o £ o o CD 0) m O- \ <3- o . 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It is apparent then that, (1) the winter export of all nitrogen parameters is over- shadowed by the larger imports ob- served during the spring, and (2) nitrate and nitrite nitrogen are ex- ported in nearly the same percentages as ammonia and organic nitrogen. As was the case with carbon and phos- phorus transport rates, fluxes were greatest during the periods of high flood and ebb tides (i.e., during April and May) . year. The reason for this is that the Nueces River must reach a flow rate in excess of 3000 cfs in order to top its bank and flood the marsh. Apparently with such infrequent flooding, it would then appear that most of the annual nutrient transport occurring in the marsh system would depend mostly on tidal inundation. Obviously, during wet years when flooding occurs more frequently and is of longer duration, the importance of nutrient flux on tidal flows will tend to be lower relative to total nutrient flux. DISCUSSION Our data indicate that the Nue- ces Deltaic marsh served as a nutrient sink during our eight-month study period. The fact that we found the Nueces marsh serving as a nu- trient sink agrees with a seasonal study performed by Espey, Huston, and Associates (1977). Other investiga- tors (Ho et al. 1970; Pomeroy et al. 1972; and Valiela et al. 1973) have also suggested that tidal marshes may act as nutrient sinks. However, most investigations have determined that brackish marshes tend to export C, N, and P on an almost continuous basis (Armstrong and Gordon 1977; Dawson and Armstrong 1975; Armstrong and Hinson 1977; and Heinle and Fle- mer 1976). Thus, the Nueces marsh offers an interesting contrast to the normally encountered brackish marsh system, at least with respect to nu- trient transport. The Nueces marsh is unlike most river-impacted tidal and brackish marshes in that it is totally inun- dated only on rare occasions. His- torical data compiled by the Texas Water Development Board (1958-1979) indicate that Nueces River spills oc- cur on an average of only 22 days a From the data in Table 1, quan- tified nutrient flux in the Nueces marsh appears slight relative to other studies (de la Cruz 1965, Teal 1962) , even though there is a defi- nite import phenomenon occurring. Carbon transport data in our study is positive — that is, we found car- bon to be imported. Teal (1962), on the other hand, suggest that as much as 45 percent of the net production of a Spartina sp . marsh is available for export (as detritus). De la Cruz (1965) described similar occurrences when he measured suspended and float- ing particulate organic matter in a Georgia marsh and found that 19 to 29 percent of the annual net production may be exported to the estuary. The fact that the importation of particulate organic carbon (which amounted to 66 percent of the TOC) was so high, is not so unusual be- cause most of the import occurred during the spring when low detrital production and increasing planktonic populations are observed. Thus, the higher TOC and POC concentration on flood tides would be expected. Chan- ley (1957) has also suggested that low export of TOC and POC, especially in the higher elevation marshes, could possibly be due to the utili- zation of detritus in the production of peat or peat-related material. 484 Phosphorus concentrations that we observed are similar to those en- countered by Heinle and Flemer (1976) in the Patuxent Estuary, but were somewhat higher than those measured by Pomeroy et al. (1962) in Doboy Sound, Georgia. The overall impor- tation of phosphorus into the Nueces marsh leads us to suspect that per- haps the marsh is somewhat phosphorus limited. This appears to contradict the findings of Armstrong and Gordon (1977) who found phosphorus to be passively exported by flood and tidal waters in a similar marsh environ- ment. They concluded that net ex- portation of phosphorus indicated that an excess of this nutrient was present and therefore was not a li- miting factor to plant production. Our data suggest that had we moni- tored the transport of phosphorus in July, August, and September of 1979, we may have indeed seen a net export of phosphorus since the June concen- tration showed a net flux of 0 and 0.4 kg/hr of total and ortho-phos- phorus, respectively, out of the marsh. However, the definite impor- tation of both total and ortho-phos- phorus during the spring months and the fact that ortho-phosphorus con- stituted 80 percent of the net phos- phorus flux, indicates that phos- phorus is not in excess in this sys- tem. Similar findings that support this hypothesis were reported by Es- pey, Huston, and Associates (1977). data tend to agree with these stud- ies, because we observed that there was a net flux into the marsh of both organic and inorganic nitrogen. The fact that most of this importation occurred during the spring growing season reinforces the nutrient-limit- ing concept. The higher organic nitrogen val- ues (0.5 to 1.5 g/m observed on flood and ebb tides during the fall and winter coincide with the vegeta- tional dieback and decomposition oc- curring at this time. Inorganic ni- trogen (NO and NQ ) concentrations were low CO. 07 g/m ) throughout the study period. In fact, the net flux for each form was close to zero sug- gesting that perhaps inorganic nitro- gen demands within the marsh are just barely being met by allocthonous in- puts of inorganic nitrogen. This supposition would seem logical if the system was not impacted by other sources of nitrogen, such as river spills, agricultural runoff, and sew- age contamination. Since the report- ed concentrations of inorganic nitro- gen are at or near their detecta- bility limits and no other sources of nitrogen were considered in the estimation of inorganic nitrogen transport, little credence can be given to our estimates of direction and magnitude of net fluxes of in- organic nitrogen. Several investigators (Valiela et al. 1973, Van Raalte et al. 1974, and Valiela and Teal 1974) have sug- gested that free nitrogenous nu- trients are readily utilized in marsh ecosystems. Valiela and Teal (1974) observed increases in the standing crop of Spartina sp. following the application of a high nitrogen fer- tilizer (without phosphorus) , thus suggesting that higher salinity marshes are nitrogen limited. Our CONCLUSION Nutrient transport in the Nue- ces marsh appears to be rather atypi- cal when compared to other high sali- nity riverine marsh systems. It is characterized by infrequent and in- complete inundation by both flood and tidal waters and tends to serve as a nutrient sink. It appears to 485 be a system where tidal flow con- tributes significantly to the trans- port of nutrients. Nutrient con- centrations within a tide are not as critical to the determination of net flux as is the flow rate between flood and ebb tides. The fact that similar amounts of nitrogen and phos- phorus were imported into the Nueces marsh suggests that both of these forms could be limiting nutrients for this system. The transport data generated in this study are meaningful in that they begin to describe the nutrient flux of a rather unique estuary. However, in order to fully describe nutrient transport in the Nueces marsh, a study period of 12 to 24 months should be employed. In addi- tion, as many of the point and non- point sources of nutrients as pos- sible (such as agricultural runoff, rainfall, sewage contamination, river spills, etc.) should be considered in the experimental design of the study. Vegetational and sediment exchange rates would also be very helpful in the determination of nutrient flux within as well as between the marsh and the estuary. Only in this way can nutrient transport between the Nueces marsh and Nueces estuary be accurately assessed. ance. The manuscript was typed by Ms. Sharon Dumas and Ms. Elaine Cur- ry. Figures were drafted by Ms. Julie Kerestin. LITERATURE CITED American Public Health Association. Standard methods for the exa- mination of water and wastewa- ter. 14th ed. Washington, D.C: APHA; 1975; 874p. Armstrong, N.E.; Gordon, V.N. Ex- change rates for carbon, nitro- gen, and phosphorus in Nueces and San Antonio Bay marshes. Re- port to the Texas Water Develop- ment Board for IAC (76-77)-06l0 by the Center for Research in Water Resources. Austin, TX: The University of Texas at Aus- tin. CRWR-152, EHE 77-05. 1977. Armstrong, N.E.; Hinson, M.O. Jr. In- fluence of flooding and tides on nutrient exchange from a Texas marsh. Proceedings of the Forth Biennial International Estuarine Research Conference. 1977, Oc- tober 2-5. Estuarine Research Federation, Mt . Pocono, PA., (in press) . ACKNOWLEDGEMENTS Results reported in this paper are a portion of a larger study of the Nueces Corpus Christi Bay System funded by the U.S. Department of In- terior, Fish and Wildlife Service (contract No. 14-16-0009-77-074). Project officer for this study was Dr. Nicholas Funicelli. Principal investigators were Dr. Don E. Hen- ley and Mr. Don G. Rauschuber. Mr. Ted Tyndall provided invaluable field and fisheries identification assist- Benton, A.R. , Jr.; Hatch, S.L.; Kirk, W.L.; Newman, R.M. ; Shell, W.W. ; Williams, J.G. Monitoring of Texas coastal wetlands. Col- lege, Station, Texas A&M Remote Sensing Center, Texas A&M Uni- versity, TX; 1977. Chanley, P.E. Survival of some ju- venile bivalves in water of low salinity. Proc. Natl. Shellfish Association. 48:52-56, 1957. 486 Cruz, de la, A. Study of particulate organic detritus in a Georgia salt marsh estuarine ecosystem. Athens, GA: University of Geor- gia. 1965:l4lp. Dissertation. Dawson, A.J.; Armstrong, N.E. Ex- change of carbon nitrogen, and phosphorus in Lavaca Bay, Texas Marshes. Volume II, The role of plants in nutrient exchange in the Lavaca Bay brackish marsh system. Report to the Texas Water Development Board by the Center for Research in Water Re- sources. Austin, TX: The Univer- sity of Texas CRWR 129, EHE-75- 06. 1975. Espey, Huston, and Associates. Marsh biology and nutrient exchange studies of three Texas estua- ries. Report to Texas Depart- ment of Water Resources, Austin, Texas. 1977; 450p. Heinle, D.R.; Flemer, D.A. Flows of materials between poorly flooded tidal marshes and an estuary. Mar. Biol. 35: 359-373; 1976. Henley, D.E.; Rauschuber, D.G. Fresh- water needs of fish and wildlife resources in the Nueces-Corpus Christi Bay area, Texas: a lit- erature synthesis. U.S. Fish and Wildlife Service, Office of Biological Services, Washington, DC. FWS/OBS-80/10; 1981; 4l0p. Ho, C.L.; Schweinsberg, E.H.; Reeves, L. Chemistry of water and sedi- ments in Barataria Bay. Baton Rouge, LA: Louisiana State Univ. Coastal Series 5:4-56; 1970. Menzel, D.W. ; Vaccaro, R.F. The mea- surement of dissolved organic and particulate carbon in sea- water. Limnol. Oceanogr. 9:138- 142; 1964. Pomeroy, L.R. , ; Shenton, L.R. ; Jones, R.D.H.; Reimold, R.J. Nu- trient flux in estuaries. Spec. Symp. Am. Soc. Limnol. Oceanogr. 1: 274-291; 1972. Strickland, J.D.H.; Parsons, T.R. A manual of seawater analysis, Bull. Fish. Res. Bd. Can. 125: 1-203; 1965. Teal, J.M. Energy flow in a salt marsh ecosystem of Georgia. Eco- logy 43:614-624; 1962. Texas Department of Water Resources. Open computer files on Texas river flow and rainfall data. 1958-1979. Valiela, I.; Teal, J.M. Nutrient li- mitations in salt marsh vegeta- tion. Reimold, R.J. Queen, W.H. eds Ecology of halophytes. New York: Academic Press; 1974:547- 563. Valiela, I.; Teal, J.M. ; Sass, W. Nu- trient retention in salt marsh plots experimentally fertilized with sewage sludge. Estuarine Coastal Mar. Sci. 1:261-269; 1973. Van Raalte, CD., Valiela, I.; Car- penter, E.J.; Teal, J.M. Inhi- bition of nitrogen fixation in salt marshes measured by ace- tylene reduction. Estuarine Coastal. Mar. Sci. 2:301-305; 1974. DISCUSSION Question: Scott Nixon, Univer- sity of Rhode Island. One thing be- fore we start speculating on the marsh being a source or a sink or comparing the different systems is 487 the problem of making the paths there. You have made the point that the concentration difference between the flood and ebb tides is very small. The net flux you have come up with is essentially a result of water balance; therefore, we have to account for the water budget. This marsh is consuming water over the year, so we have to reconcile the fate of the stored water. I'm won- dering, in light of the work done at South Carolina and Virginia in trying to address the problem, how hard it is to get a good mass balance through the bridgeway with the cur- rent meter measurements or area height models? How good do you think your measurements really are when it comes to coming up with an average concentration and a one spot velo- city measurement in the pass? Answer: We noticed that the tidal amptitude is very low in this area, that the current speeds were very slow by measuring the current with a weighted float technique. This may not be state-of-the-art, but it proved to replicate itself very well during each measurement. Since the nutrient portion of this study was a small part of the over- all study, I felt that at the time it was the best that we could do. I hope that answers your question. Question: Brian Fry, Port Aran- sas Marine Lab. I was wondering, is it possible that the water measured on the flood tide actually comes back on the ebb tide; that actually this marsh is not very well flushed but the water just goes say a hundred meters downstream and then comes right back? Answer: Well, our measurements were taken at two locales (1) where the Rincon Bayou intercepts the Nue- ces Bay and (2) approximately two miles up the bayou in the marsh. We noticed, via staff gauges, signifi- cant changes in tidal amplitude at both measurement stations indicating substantial water movement. However, since the marsh is in a low tidal amplitude area, most tidal pools and tidal channels are not completely drained during a complete tidal cy- cle. Thus, in answer to your ques- tion it is possible that flood and ebb tide waters are one and the same with respect to nutrient and particu- late content and that the marsh is not very well flushed. It is, how- ever, difficult to imagine that this phenomenon is more the rule than not and that very little bay water is actually transported in and out of the marsh system. 488 ESTUARINE BENTHIC COMMUNITY DYNAMICS RELATED TO FRESHWATER INFLOW TO THE CORPUS CHRISTI BAY ESTUARY R. Warren Flint and Steve C. Rabalais University of Texas Marine Science Institute Port Aransas Marine Laboratory Port Aransas, Texas ABSTRACT In September 1979 Corpus Chris- ti Bay was impacted by tropical storm-intensity rains that resulted in an intensive period of freshwater inflow to the bay, dramatically de- creasing salinity below normal levels for more than a month. The existence of an historical data base on benthic infauna for this estuary allowed an investigation to be conducted con- cerning effects of this intensive freshwater inflow on the estuarine benthos. Several months after the inflow event, densities of dominant infaunal populations increased to levels never observed and producti- vity of the benthos, as represented by biomass changes, increased sub- stantially over previous years. We speculated that the nutrients as- sociated with the intensive freshwa- ter inflow increased the primary pro- ductivity of the estuarine ecosystem. This increased productivity was, in turn, eventually reflected by the benthos. These data may provide a missing link in the correlations be- tween freshwater inflow events in south Texas estuaries and yields of some of the important fisheries such as shrimp. INTRODUCTION Bays and estuaries along the coastline of the northwestern Gulf of Mexico are strongly influenced by freshwater inflow and its associated nutrients. This is true primarily because these bays and estuaries are located in a semi-arid climate re- ceiving usually less than 70 cm of rainfall per year (Flint and Rabalais 1981). It is thought that in these hypersaline systems, freshwater in- flow, which is very unpredictable in nature, affects estuarine community species composition, the vitality and productivity of estuarine food chains, and the harvests of many fisheries related to the estuarine ecosystem, such as shrimp. The links between the inflow of fresh water and the resulting effects as reflected by the changes in fishery harvest, how- ever, are presently not well under- stood. During the 24-hour period be- ginning with the evening of 18 Sep- tember 1979, an extensive low pres- sure system engulfed the south Texas coast and heavily impacted the Corpus 489 I co u o 00 d a, e co w oo d •H 5 o w co CO X 0) H ■ H 15-1 3 l0 < CO 5- OJ TRANSECT 2 SONDJFMAMJJASONDJFMAMJJASONDJFMAMJJASONDJFMAMJJASONDJF 1974 1975 1976 1977 1978 1979 lOOi ^ CO o ui or o 80- LU LU CD 0_ 5 CO 60 3 ^ < 40 2| 2 £ 20-| 2 TRANSECT 2 SOND JFMAMJJASONDJF MAMJJ A S 0 N 0 JFMAMJJ ASONOJ FMAMJJ A S 0 N 0 JF 1974 1975 1976 1977 1978 1979 SONOJFMAMJJASONDJFMAMJJASONOJFMAMJJASONDJFMAMJJASONOJF 1974 1975 1976 1977 1978 1979 Figure 2. Plots of salinity, meaxi number of infaunal species and mean in- faunal density (individuals/O. 09m ) between September 1974 and February 1979 for the shallow water sampling stations (transect 2, Stations 4-6). 494 40-i 30- 20 < V) \0- ~i 1 1 1 r -i 1 r t 1 1 r 30-1 D >- 20- o 10- □ THARYX SETIGERA ■ LUCINA MULTILINEATA iu -4" UUnJ r30 -20 CO z Q -10 CD z UJ Q 225- 150 7 5- ■ MEDIOMASTUS CALIFORNIENSIS □ STREBL0SPI0 BENEDICT! u i i i i r JASON 1977 I JU J A S 0 N 1978 Ll A S 0 1979 -60 D 40 > UJ D -20 Figure 3. Comparison of late summer and early fall salinities and densities (individuals/0. 09m ) for some of the dominant infaunal species during the collection years 1977, 1978, and 1979. 495 CO 120 o LU a CO u. O or LU CD ID < O 100- 1975 1976 1977 1978 SAMPLING DATE 1979 1980 5600. >_ 4200 LU Q _, 2800 O 1400- _STATI0N 4 .STATION I SEPT FEB 1975 SEPT FEB 1976 SEPT SEPT FEB 1977 SAMPLING DATE FEB SEPT FEB SEPT FEB 1978 1979 I960 Figure 4. Comparisons of total number of infaunal species and total infaunal desities (individuals/0 .09m ) for sampling Stations 1 and 4 over the five year period prior to the freshwater inflow event of September 1979 and after this inflow period. 496 lu a, ll. — Q. uj CO CD rv_ Q. LU CO 1^- CD |^_ »- 0_ LU CO CO LU h- LJ Lu 0> h- 0. LU CO LO CD 1^ LU Lu 0> f- Q. LU CO o •H U 0) ft rl CO 0) >> 0) > •rl 4-1 0) 43 • •P T3 O U -H 01 U > 0> o ft O UO 4-1 CO Z 00 a *o — ■ •H (3 _l r—l <0 Q_ ft :> <0 r~- < T— t u CD o u 4-1 0) 4=> >. e +J 01 •H 4-1 r-l O, •rl 0) 43 Cfl CO 4-1 4-1 •H O 3 c j-i 0) d 0) r-l > CO 0) (3 d 3 CO O 4-1 r-l d 4-1 •H C •H 4-1 o u 01 d 4-> O CO w 3 ■H 43 u w CO OJ ft u a 4-1 O U OJ 43 +J LO O •P OJ u u 3 O 00 -H •rl U rM ft Aiinigvnn03 ivNnvdNi 497 further exhibited some of the dyna- mics that were occurring in the ben- thos after the inflow event. Equi- tability of the infauna varied tre- mendously over the entire study du- ration (1974 to 1979). A distinc- tive decrease in this community mea- sure was observed, however, a short time after the intense freshwater in- flow event, with equitabilities for the two observation stations reflect- ing their lowest values for the en- tire six years of study. This pat- tern suggested that although there was an increase in number of infau- nal species (Figure 4) after the in- flow event, the corresponding in- crease in total infaunal density was due to increases in a few populations which then dominated the community structure. The dominance by a few species in respect to density, caused the evenness of species distribution to drop significantly (Figure 5). Evaluation of infaunal commun- ity structure using the numerical classification technique of cluster analysis further documented the dra- matic changes that occurred in the Corpus Christi Bay benthos follow- ing the freshwater inflow event in September 1979. An examination of the similarity in community struc- ture between all collection periods for station 1, between 1974 and 1980, with the exception of the early sum- mer months, showed a very striking pattern (Figure 6). The period of January to April 1980 exhibited a dissimilarity with all other col- lection periods at a level greater than 65 percent. The dissimilarity in benthic community structure be- tween this period and all others was strong enough to override any natural seasonal patterns that may have ex- isted in the data. The same pattern was observed for station "4 benthic community structure. A closer evaluation of speci- fic time periods during the total study period served to emphasize the effect that the freshwater inflow event had on the benthos. Figure 7 compares the early fall periods (July to October) and the winter pe- riods (December to March) for all collection years at stations 1 and 4. The highest dissimilarities ob- served for any collection periods for the fall were slightly over 40 percent with no significant separa- tion for the 1979 collection periods. In contrast, the winter dendrograms exhibited highest dissimilarities around 60 percent with a distinct separation of the winter 1980 col- lection periods. This ability of the cluster analysis technique to sepa- rate benthic community structure characteristics of winter 1980 from all other winter periods while not being able to also separate charac- teristics for fall 1979 in respect to previous fall periods further indicates that the benthos was def- initely changed by the freshwater inflow. Furthermore, there appeared to be a slight lag in the overall response of the benthic infauna to this natural disturbance of the estuarine ecosystem. Although the intensive inflow event occurred in September and salinities remained low well into October, the benthos did not reflect the dramtic increase discussed so far until December January. A very good example of these changes is derived by focusing on one of the dominant populations in the study area. Figure 8 illus- trates the size class distribution for the bivalve Abra aequalis during February and March of 1979, prior to the inflow event and during February and March 1980, after the inflow event. Several trends are apparent. 498 October November August November July September October October August December December November July August August March April January December February October November March July February March April Oec ember January January March April January February September December January July August October November September September November October April July February March April February December February March April January 20 STATION I PERCENT DISSIMILARITY 40 60 80 l_ 100 1 1 1 1 \ 1 - I 1 1 1 1 L 1 ■ 1 1 ZL i "1 i 1 I l 1 1 " 1 _l_ 1 1 1 1 Figure 6. Dendrogram from the cluster analysis results of infaunal species composition evaluation for all collection periods at Station 1 over the study duration with the exception of the summer months, May and June. 499 < _) J Z z O w _ o 1- a: < or u Z z o < I ^ % ~ 3 I 5 a I e I •! 2 o -I 2 < I- UJ z o < t- 10 _=x^ ^A I t t a l. a ■JS u-l sO »J VO ■* O -J -1 < « O •o E => -C 3 C L. o -> O I- X X o o -s a u. x **. W 0) •H U 0) Q- C0 i— 1 W C! 3 • to >% 4H T> C 3 •H 4-> en IH O >> t0 c/3 CQ 4-1 i— 1 ■H 3 4-> tn VI > 3 i— 1 ft to S-l c o fO (_> ^ 4-1 in 3 oo i— 1 a u ■H S-l oo 3 c "O ■H 4-J w to T3 u O 4-1 •H M S-l 3 UJ i— 1 ft .— 1 ■H S-l r— 1 t/1 1— 1 to S-l O <4-l S-l o <4-l CO = fO o S-l OO 4-1 m o S-l 3 T3 d Q to > c o ■ •H r-~ 4J •H cu CO S-l o 3 a « s ■r-l o t*4 o 500 en < 3 O LlJ < < cc < < 5 ■a in x CO sivnaiAiaNi jo yaawnN nvioi T3 d TO >> S-i 00 CJ •H S-I 3 TO 3 CT< 01 TO TO U 3 O c/i G o ■H £) TO i— I 3 P- O a, u o CO d o u] ■H « . 00 B o u .2 " w « ■H T3 >, S-I w TO m 3 TO *-• U o o o Q. CO CD 0> T O O o 10 o o o o (^ 6CT0/6w) o o o -> C 3 +J d (-1 O CO w w E o CO c 3 CO "4-1 e c £ CO 4-» s >. (0 4-t « ° -H • (/] u o 3 U 60 ■H C p4 -H ssvwoia Q3ansv3ivM ivioi 503 28,000- STATION 1 •* in < 21,000- o CD Y = 3 09X * 229 1 n = 33 r =0 83, P< 0.001 _J < Z j=> 14,000- Ll z * < 1- o H 7,000- * * ^-^^^ * * « * • *^ ^"^ * • * 50 1500 3000 4500 TOTAL INFAUNAL DENSITY 6000 12,000- STATION 4 y = I.03X* 177.8 * ID CO n = 33 r =0.70, P<0.00l * < 2 O CD _l < 8,000- z 3 < U. z * _J < H ^ 4,000- "-"■"^ * * * * 1 2000 4000 6000 8000 TOTAL INFAUNAL DENSITY Figure 10. Linear regression best-fit curves for total infaunal biomass (mg/0.09 m ) correlated against total infaunal density (individuals/0.09 m ) at Stations 1 and 4 in Corpus Christi Bay. 504 2 2 O o 1 »-*■ < < h- H to (/) 1 1 ■■ MOUNI U3J.VMHS3HJ SS VIAIO "1V101 - 0) ON U 0) CTN H 3 i-i T: os xi r~- o i o u i-i m s-i S -Q o a u u s > u v 0^ i ON ^ CD T3 •H t-l (LI W d 3 flj 4-1 c o u o o 4-1 0) 00 3 2 •r-l ^ I ™ ^ ° .a •H g IM a, s-i o u O 73 4-> d (0 O i-i 00 05 E C nj o s-i -H 00 4-1 O (8 4J 4-1 oo to •H se n O W 01 o 3 ■H '-' 4_) (0 TO > cr "o i- d 3 i-i rH oo 2 S3 !-> O i-l OO a\ 41 i—i '- i d vo OO r-~ ■H ON (JL, 1-4 d n ai S-l ft HI T3 41 4-1 «3 OO i—i co 3 A3 u e r-l O (0 -H O XI 505 of Beulah and the effects of these rains were therefore confounded and not totally interpretable. The logic involved in focusing on the dynamics of populations on the sea floor for this study in- cluded the fact that because of the sedentary nature of these fauna, they represent a potential barometer in- dicating changes to the system unlike fish and many planktonic fauna which are relatively mobile and able to avoid adverse conditions prevailing over a preceding point. Furthermore, the benthos represents an important component of the estuarine ecosystem not only because of their trophic re- lationships with important fisheries but also because their activities and functioning within the sediments play a large role in material fluxes from the sediment sinks, including the nu- trients which potentially drive the production of the system. Unlike the few previous studies documenting accounts of effects of freshwater flooding on the estuarine benthos (Stone and Reish 1965; Boesch et al. 1976), the results of this study suggest that the inflow event had a positive impact on the func- tioning of the ecosystem. Stone and Reish (1965) reported mortalities of benthic invertebrates resulting from heavy rainfalls in the upper portions of some California estuaries. Wells (1961) reported effects of freshwater inflow from a series of successive hurricanes on oyster reef fauna of the Newport River estuary in North Carolina indicating mass mortalities and community structure changes. In a similar fashion, Thomas and White (1969) observed high invertebrate mortality following an unusually heavy spring thaw discharge into the Bedford River, Prince Edward Is- land. In contrast to the above reports concerning small estuarine systems which do not have the volume of water to buffer against dramatic salinity changes, two studies in large estua- ries also showed either high mortali- ties and community structure changes or that salinity changes simply de- termined the distribution of fauna. Boesch et al. (1976) observed the benthos in the lower Chesapeake Bay after Hurricane Agnes and found that many abundant species were eliminated from the shallow bottoms and several species were eliminated or reduced in abundance in the deeper waters after extensive freshwater intrusion into the estuary. Fradette and Bourget (1980) found that numbers of organ- isms and biomass decreased markedly from higher salinity areas to areas affected by freshwater inflows in the Gulf of St. Lawrence. In the present study, from the cluster analysis results it would ap- pear that community structure changes had occurred after freshwater inflow (Figure 6 and 7). In fact a few spe- cies did occur which had not been present previously increasing the number of species present in the bay (Figure 4) . The most striking ben- thic changes that occurred, however, were the tremendous increases in densities (Figure 4) which had a pro- found effect on the clustering tech- niques employed. The dominant fauna did not disappear or change, as was observed in other studies. These fauna simply increased their produc- tion of biomass and numbers to rec- ords never observed before, in res- pect to the historical data base. There is a possibility that in the previous studies cited above, either because of the smallness of the estuary or becuase the salinity changes after freshwater inflow were so dramatic (Boesch et al. 1976) that 506 the impact to the system was delete- rious. Corpus Christi Bay is a hy- persaline estuary and the events des- cribed here included measured changes in salinity from the normal 25 to 30 ppt down to 11 ppt at one point in the bottom of the channel. This change may not have been sufficient to produce the same negative impact to the system as observed in other studies . We conclude from this study, however, that periodic freshwater in- flows to the Corpus Christi Bay eco- system are extremely important in maintaining productivity of the eco- system. We hypothesize that the freshwater inflow represents an in- crease in nutrients to the estuarine habitat which is then reflected by and increase in primary production of the system. Much of this in- creased primary production is ulti- mately diverted to the benthos (Flint and Rabalais 1981) and ulti- mately stimulates increased ben- thic infaunal production, represent- ing additional food supplies to many of the important area fisheries such as shrimp. The lag time observed in this study between the inflow event and changed dynamics of the benthos is represented by dynamics in the lower trophic levels that must occur before the events are reflected by the benthos. Therefore, from the data pre- sented above, we feel that the kind of freshwater inflow observed dur- ing September 1979 is definitely be- neficial to the entire estuarine eco- system. The significance of docu- menting the effects within the Corpus Christi Bay system are obvious. En- vironmental managers in this area are constantly faced with decisions in- volving freshwater resources and ef- fects to the estuary, related to the regulation of their flows. In addi- tion, since the benthos is included in the trophic webs involving many of the important fisheries of the area, such as shrimp, the indirect effect to the fishery, reflected by future catch statistics correlated to the heavy freshwater inputs, and their effect to the benthic populations provide sound information to further test some of the models developed by environmental managers in recent years (Martin et al. 1980). We feel that this information on the benthos provides a missing link in the cor- relation observed between freshwater inflow and shrimp statistics. LITERATURE CITED Boesch, D.F.; Diaz, J.; Virnstein, R. W. Effects of tropical storm Ag- nes on softbottom macrobenthic communities of the James and York estuaries and the lower Chesapeake Bay. Chesapeake Sci. 17:246-259; 1976. Day, J.S.; Field, J.G.; Montgomery, M. Use of numerical methods to determine the distribution of benthic fauna across the conti- nental shelf of North Carolina. J. Animal Ecol. 40:93-126; 1971. Downing, J. A. Aggregation, transfor- mation and the design of benthos sampling programs. J. Fish. Res. Board Can. 36:1454-1463; 1979. Flint, R. W. , Rabalais, N.N. Environ- mental Studies of a marine eco- system: south Texas outer con- tinental shelf. Austin, Texas: Univ. of Texas Press; 1981:235p. 507 Flint, R. W. ; Younk, J. A. Estuarine benthos: Long-term community structure variations, Corpus Christi Bay, Texas. Estuaries. [1981] in press. Mills, E. L. ; Fournier, R.O. Fish production and the marine eco- system of the Scotian Shelf, eastern Canada. Mar. Biol. 54: 101-108; 1979. Fradette, P.; Bourget, E. Ecology of benthic epifauna of the estuary and Gulf of St. Lawrence: fac- tors influencing their distribu- tion and abundance on buoys. Can. J. Fish. Aquat. Sci. 37: 979-999; 1980. Lance, G. N.; Williams, W.T. A gene- ral theory of classif icatory sorting strategies. I. Hierar- chical systems. Computer J. 9:373-380; 1967. LLoyd, M.; Ghelardi, R.J. A table for calculating the "equitability" component of species diversity. J. Animal Ecol. 33:217-225; 1964. Martin, Q. ; Powell, G. ; Thorn, G. ; Chang, G.; Belaire, S.; Gold- stein, A.; Taneman, G. Lavaca- Tres-Palacios Estuary: A study of influence of freshwater in- flows. Austin, TX: Texas Dept. Water Resources; Pub. //LP-106; 1980. Pielou, E.C. Shannon's formula as a measure of specific diversity: its use and misuse. Am. Natural- ist 100:463-465; 1966. Scheefe, H. The analysis of variance. New York: Wiley; 1959. Stone, A.N.; Reish, D.J. The effect of freshwater runoff on a pop- ulation of estuarine polychae- tous annelids. Bull. So. Calif. Acad. Sci. 64:111-119; 1965. Thomas, M.L.H.; White, G. N. Mass mortality of estuarine fauna at Bideford, P.E.I. , associated with abnormally low salinities. J. Fish. Res. Board Canada 26: 701-704; 1969. Wells, H.W. The fauna of oyster beds with special reference to the salinity factor. Ecol. Monogr. 31:239-266; 1961. 508 THE EFFECTS OF FLOODS ON THE ZOOPLANKTON ASSEMBLAGE OF SAN ANTONIO BAY, TEXAS DURING 1972 AND 1973 Geoffrey A. Matthews National Marine Fisheries Service Galvestion, TX 77550 ABSTRACT Plankton tows and hydrographic measurements were taken encompassing a single flood in 1972, and three floods in 1973 in San Antonio Bay. The shallow bay was rapidly flushed by influx of flood waters as was in- dicated by reductions in salinity and in the densities of the dominant species, Acartia tonsa . Floods re- placed the typical estuarine zoo- plankter (Balanus sp . nauplii, Oi- thona colcarva , Paracalanus cras- sirostris , Oikopleura spp . , and the cyphonautes larvae of Membranipora sp.) with the freshwater ones (Diap- tomus spp., Cyclops spp., Arcella discoides , Moina sp., Diaphanosoma sp. and other cladocerans) . During the 1972 flood, total zooplankton densities fell from 10,800/m before the flood to 3,400/m after the flood, but they increased rapidly when the river flow returned to base level. After the three floods in 1973, a cumulative decrease in total density of over two orders of magni- tude was found. There had been in- sufficient time to reestablish pre- flood densities between each flood. The rapidity with which densities were re-established and the areas in which these increases were first found indicates the majority of the density changes were due to influx of zooplankton-rich bay water from Espiritu Santo Bay, rather than from population explosion by surviving re- fuge populations. It is important to note that the seasonal occurrence of a flood may severely reduce the sur- vival of a bay's annual recruitment of economically important species whose larval stages are members of the zooplankton or which depend on zooplankton as food. It is also important to note the interdependency of these estuaries as currents flow carrying life from one into the next. INTRODUCTION Most estuarine plants and ani- mals depend in some manner on fresh water from rivers and streams for their survival. The variability in quality and quantity of the fresh- water inflow during a year and through several years can lead to dramatic environmental changes in an estuary, and thus in the organ- isms living there. With the in- creasing use of estuaries for var- ious economic purposes it has be- come essential to know what to ex- pect when certain environmental factors change. The objective of this paper is to describe the effects of floods on the zooplankton of a shallow estuary, San Antonio Bay, Texas . 509 MATERIALS AND METHODS STUDY AREA San Antonio Bay covers an area of about 305 km and is located in the middle of the Texas coastline at latitude 28°20' North and longi- tude 96°45' West. It is a shallow bar-built estuary with an average natural depth of 1.5 m and contains many shallower oyster reefs and few places as deep as 3 m, however, re- cent shell dredging in the middle bay area has increased the depth in about 20 percent of this section to 4 m. Matagorda Island isolates San Antonio Bay from the Gulf of Mexico, and most salt water must flow into Matagorda Bay and through Expiritu Santo Bay before reaching San Antonio Bay. Fresh water from the combined flows of the San Antonio and Guada- lupe Bay flow into upper San Antonio Bay (Figure 1). Annual evaporation slightly exceeds annual rainfall in normal years. SAMPLING REGIME Eleven sites were selected to represent the bay (Figure 2). To facilitate biological analyses with respect to salinity, these sites were partitioned into: Zone 1 = the upper bay, Zone 2 = the middle bay, and Zone 3 = the lower bay. Zooplankton was collected at each site twice per month by making a one-minute oblique tow with a #10 mesh (150 micron pore width) conical Nitex net which had a mouth diameter of 0.5 m and a length of 1.3 m. A flowmeter mounted in the net mouth measured the amount of water fil- tered on each tow. After each tow, the net was washed and the bucket's contents were preserved in 5 to 10 percent Formalin. Water temperature and salinity were taken immediately following the tow. DATA COLLECTION River flow rates were obtained for the rivers and creek from the U.S. Geological Survey annual re- cords. Ten-day average river flow rates were calculated for each sam- pling time. Each average was based on the sum of the daily flow rates of each of the three tributaries for the day of sampling plus the nine previous days, i.e. the summation of 30 values divided by 10. SAMPLE ANALYSIS Methods similar to those used by Hopkins (1966) were used to ana- lyze each zooplankton sample. A sub- sample taken with a Hensen-Stemple pipet and containing between 200 and 1,000 organisms was examined from each tow. Each organism was identi- fied to the lowest taxon possible-- usually to genus or species. Counts from the subsample were converted to numbers per cubic meter of bay water. RESULTS AND DISCUSSION THE SINGLE FLOOD OF 1972 Collections on May 4, before the flood, showed fairly high densities of zooplankton in Zone 1 and moderate levels in Zones 2 and 3 (Table 1). The composition of the zooplankton was typically estuarine for all zones at this time. Just before the flood there was a freshet which introduced sufficient fresh water to reduce the 510 Figure 1. Components of San Antonio Bay System and vicinity. (1) Mission Lake (2) Guadalupe Bay (3) Hynes Bay (4) San Antonio Bay (5) Ayers Bay (6) Mesquite Bay (7) Cedar Bayou (8) Espiritu Santo Bay (9) Shoalwater Bay (10) Barroom Bay (11) Matagorda Bay (12) Pass Cavallo (13) Guadalupe River (14) San Antonio River (15) Green Lake (16) Seadrift, Texas (17) Austwell, Texas (18) Port O'Connor, Texas (19) Aransas Wildlife Refuge (20) Matagorda Island (21) Victoria Barge Canal (22) Intracoastal Waterway. 511 0 12 3 4, i i i ■ i km Figure 2. Collection sites in San Antonio Bay, Texas meters in parenthesis. Depths are given in 512 o ■H C o 4J - < d to o o 1—1 4-1 U CU 4J 4-1 <0 T3 c to CU 4-1 CO 0) = 1) •H ij — 1 O cu Cm T3 ■H ■a to J3 c •H CO OJ s-l <+H CO 4-1 CU o •H 4-> a •H o CO •H a 4-1 0) a T5 — •H c u o 4-1 4-1 d ■X o d o (0 i— i cu o. — o H o Cx] co to X •~H CU H cu 1— 1 •s 4= >> CO to H cc u cu 4-> to X! CO cu S-i O o o o S-l 0J 4-1 to 3 -d to cu S-l o H Sj CU 4-1 to -d CO CU S-l o H o ^H O C^ m o U~l 4-> co CO O »* ^O H CNl o o o o in cm O CN m i-h O CO O i-i co CN i—i l-» l-H > Cn CO < 2 CO m O O o o o o r»- o o m en m vO a\ o> o\ r^ o 00 00 m \D o CO in o CN a o o hJ P>H CU CU >> > >> d d i—l i— 1 CO d d d 3 s >-> r> •d •-) CO r*. CN vo O CN CN CN 513 average salinity in Zone 1 to about 7 parts per thousand. Total zooplank- ton density in Zone 1 increased slightly over its value at the pre- vious sampling (19 April), but it de- creased in both Zones 2 and 3. A few common freshwater zooplankters such as Cyclops sp . , Diaptomus sp . , and cladocerans were introduced into Zone 1, but no freshwater-related changes in diversities were found in the zooplankton of Zones 2 and 3 at this time (4 May) . The flood began on May 8, peak- ed on May 16, and had decreased to a freshet level by the sampling trip on May 23. Salinities in all zones had fallen to between 1 and 4 parts per thousand. Several changes had oc- curred in the zooplankton, and total zooplankton densities in Zones 1-3 had decreased to 20, 73, and 26 per- cent, respectively, of what they had been 19 days earlier. The percent of the total density contributed by taxa of freshwater origin had in- creased from 1.3 to 54.5 percent in Zone 1, and from 0 to 17 percent and 43 percent for Zones 2 and 3, and most of the dominant taxa in all three zones were of freshwater origin (Table 2). By the collection time of June 7, the river flow rate had decreased to only 5 percent of the maximum flood flow rate, but the river rate was still slightly elevated above base flow rate. Salinity remained depressed in Zone 1 and increased only very slightly in Zones 2 and 3. Zooplankton densities were now even lower in Zone 1 , but they had dou- bled in Zone 2 and had quadrupled in Zone 3. Contributions by taxa of freshwater origin to these den- sities were down to 7.4, 0.4, and 0.9 percent for Zones 1 to 3, respec- tively, and only in Zone 1 were they representing about half of the domi- nant taxa (Table 3) . Diversities in all zones were lower than during the previous sampling. The percent of the diversity contributed by fresh- water taxa was also lower, but it was still between 44 and 18 percent. Freshwater inflow increased to freshet levels again on June 19, just a few days prior to sampling. Sali- nity remained at about 1.5 parts per thousand in Zone 1, but slight in- creases in salinities to about 6 and 10 parts per thousand were found in Zones 2 and 3 respectively. Densi- ties reached a low in Zone 1 at 584/ m , but increased in Zones 2 and 3 to above 20,000/m . Freshwater taxa ac- counted for virtually nothing in Zones 2 and 3. Diversity increased in Zones 1 and 2 but not in Zone 3. Freshwater taxa accounted for 54 per- cent and 12 percent of the diversity in Zones 1 and 2 respectively; none was found in Zone 3. All of the dominants in Zone 1 were of freshwa- ter origin except Acartia tonsa . River flow rate continued to decrease after the spike in late June, and salinity in Zone 1 final- ly increased to 2.5 parts per thou- sand at the time of the sampling on July 6, but it remained unchanged in Zones 2 and 3. Zooplankton den- sities increased an order of magni- tude in Zone 1 and also increased again in Zones 2 and 3. Contribu- tions by freshwater taxa to the den- sity in Zone 1 decreased to about 3 percent and they increased in Zone 2 to 0.5 percent. Diversity de- creased by almost half in Zone 1, just slightly in Zone 2, and 514 o •r-l = o 4-1 - < d 03 <*) a •H CM r- s 4-1 o o o o 14 X! W fa 03 4-> O H O O O O r- p- co i-h \0 O O CM OO O O M3 o CO >3- ■vT r-l rH CO co oo lO X 03 1+4 4-> O u > 03 03 o 03 4-1 O H 14 UJ 4-1 0J 3 -C 1/3 OJ U fa o O^ CO o so CM o ^3- m co CM co p- CM so CO O SS as co co co CO i-i i-i CM in co <3* m CM in oo vj3 CM O0 CO OJ 4-1 03 Q 1^ < >> 03 s a o o .-J fa CD CU >> > >> d a r— 1 i—l 03 3 3 3 3 s I-i l-i l-J •-3 CO r-~- CM vO O CM CM CM Table 3. Composition of the zooplankton community in each zone before, during, and after the May 1972 flood in San Antonio Bay, Texas. Each zone's composition is represented by its 12 most abundant taxa . * indicates taxa of freshwater origin. Surface and bottom salinities (o/oo) are given for each zone on each date. ZONE 1 ZOSS 2 zo:;: Surface: 1.5 Botton : 1.7 Acartia tonsa Asplanchr.a sp. Gastropod velioers ♦Cyclops sp. •Sinocephalus sp. Harpacticoids *Diaptonus spp . •Arcella disccides *Perissocyt her idea sp. Copepod nauplii Ergasilus sp. Ostracods Date: 7 June 1972 4.7 5.3 Acartia tonsa Balanus sp . nauplii Paracalanus crassirostris Cyphonautes larva 4A Copepod naur 1 : : Oithor.a colcarva ♦Cyclops so. Polychaete larvae Asplanchna sp. Epistylis sp. Ergasilus sp. •Brachionus quadridentatus 5.8 6.1 Acartia ton;a Balarus sp. nauplii Pseudodiaptcms cor Paracalanus crassir O.Thonantes larva = Oithor.a colcarva Copepod nauplii Spionid larvae Fish eggs Polychaete larvae •Brachionus cruadridc Bivalve velioers Date Surface: 1.5 Bottom : 1.7 Acartia tonsa •Ilyocryptus spir.ifer •Cyclopoids •Epheiteropterar. larva •Diaptor-.us spp. •Trooorv-cioos orasi :s *Diaphanosona sp. 5rachi.or.us cl icati lis •Apocyclccs paj~.ar.er ;Sis *Arce 11a discoides *F.nabcocoel worn: *.M.oina m crura 22 June 5.8 6.5 Acartia tonsa 1972 Balanus sp. nauplii Gastropod veligers Oithona colcarva Copepod nauplii Her.icyclcps sp . copepodic Keopanope texar, j zoea Kalicyciops fos'-eri Spionid larvae Ergasilus sp. Calliar.assa sp. sl zoea •Ostracods, Cyprididae 9.3 10.0 Acartia tonsa Balar.us sp. nauplii Spior.id larvae Copepod nauplii Pseudodiaotor-.us coror.atus Gastropod veligers Oithor.a colcarva Bivalve veligers Calliar.assa sp. -1 zoea Halicvclocs fosteri Gobicso~3 bosci larvae Rithropar.oDeus harrisii Da te: 6 July 1972 Surface: 2.6 6.6 9.4 Botton : 2.3 6.6. 9.5 Acartia tonsa Acartia tonsa Acartia tor.sa Balanus sr>. naucln Balanus sp . nauplii Balar.us sp. nauplii •CVclOOS St. Cooeood nauolii Pseudodiaotcr.us coror.atus Copepod nauplii Paracalanus crassirostr is Tir.tmno^sis sr . Paracalanus crassirostris PseudodiactoTnus coronat us Oithcr.3 colcarva Gastropod veligers •Ostracods Pseudod lap tonus coror.atus Asp lancnna sp . Harpacticoids Ergasil js sp. •Cyclopoibs Gastropod veligers Polychaete larvae Oithona colcarva Ergasilus sp . Tiatyias quadncorr.is 'Eucyclops sp. Brachyuran zoea Copepod nauplii Fish eggs Bivalve veligers Gastropod veligers Anchoa mitchilli larvae Spior.id larvae CvDhcnautes larva &A Surface: 2.6 Bottom : 3.0 Acartia tor.sa Balanus sp. nauplii Gastropod veligers Copepod nauplii Spionid larvae •Arcella discoides Halicvclor-s fosteri Bivalve veligers Pseudodiac tonus coronatus Tintinnorsis sp ■ Balanus sp. cypris Oithona colcarva te: 20 July 1972 8.1 8.2 Acartia tonsa Balanus sp . nauplii Copepod nauplii Brachionus plicatilis Kneru, op s i s nccradyi Gastropod veligers Favella pananensis Balanus sp . cypris Cypr.onautes larva **A Bivalve veligers Pr.eudoci aotorrus coronatus 9.5 11.8 Acartia tonsa Balanus sp . nauplii Oithor.a colcarva Copepod nauplii Cyphonautes larva -A Pseudodiap tonus coronatus Balanus sp. cypris Mneniopsi s mccradyi Spionid larvae Paracalanus crassirostris Neocanooe texar.a zoea iicatilis Faracalanus crassirostris Brachionus 516 Table 3. Concluded. ZONE 1 ZONE 2 Date: 19 April 1972 Surface: 12.2 15.2 19.6 Bottor. : 12.0 15.6 19.6 Acartia tonsa Acartia tonsa Acartia tonsa Gastropod veligers Balanus sp. nauplii Oithona colcarva Balanus sp. nauolii Oithona colcarva Pseudcdiaotomus coronatus Bivalve veligers Uca sp. zoea Oikocleura sp. •Ostracod *2 Tintmnopsis sp . Paracalanus crassirostris Tmtinnopsis sp . Pseudodiaotomus coronatus Fish eocrs Balanus sp. cypris Gastropod veligers Cyphonautes larva -A Copepod nauplii Bivalve veligers Cooepod nauolii - Oithona colcarva Balanus sp. cypris Ophiopluteus larvae Spionid larvae Spionid larvae Balar.us sp. nauclii Pseudodiactornus coronates Paracalanus crassirostris Balanus sp. cvpris Paracalanus crassirostris Copepod nauplii Anchoa nitchilli larvae Date: 4 Kav 1972 Surface: 6.7 19.7 23.6 Bottom : 7.0 20.1 23.9 Acartia tor.sa Acartia tonsa Balanus sp . nauplii Gastropod veligers Balanus sp. nauplii Oikcrleura sc . •Cvcloos sc. Paracalanus crassirostris Acartia tonsa Balanus sd. nauolii Cyphonautes larva -A Ophiopluteus larvae Bivalve veligers Oithona colcarva Cyphonautes larva *Cladocerans Bivalve veliaers Oithona colcarva •Diaotonus soc . Gastropod veligers Copepod nauplii Copepod nauplii Brachyurar. zoea Fish eacs Ergasilus sp . Oikorleura sc. Paracalanus crassirostris Paracalanus crassirostris Cooeood nauolii Bouaamvillia sp. Cyphonautes larva *.-. Harpacticoics Eivaive velicers Balanus sp . cyrri: Balanus sp. cypris Polychaete larvae Date: 23 Kay 1972 Surface: 1.1 l.S 3.9 Botto-. : 1.8 2.0 4.2 Acartia tonsa Acartia tonsa Acartia tonsa •Cladocerans •Cyclopoids •Cyclopoids •Cyclopoids •Diaptornus spp. Oithona colcarva •Cyclops vernal is •Calanoid (freshwater) •Eurvtenora affir.is •Arcella discoides •Arcella discoides •Eurytenora sp . •Apocyclops panamensis •Microcycloos sp. •Arcella discoides •Diaptonus spr . •Moma sp . •Diaotor.us St. •Eurytenora sp . •Dianhanosoma so. •Moina micrura •Brachio.nus quadridentatu 3 •Cladocerans Gastroood velioers Tintmnids •Cyclops sp. Nematodes Copepod nauplii Harpacticoids •Diaohanosor^a sp . •Cenodaoh.ma st . •Cyclops vemalis Balanus sc . nauolii 517 remained unchanged in Zone 3. Fresh- water taxa accounted for only 15 per- cent of the diversity in Zone 1, 16 percent in Zone 2, and 3 percent in Zone 3. The zooplankton throughout the bay was returning to its estua- rine dominants with few exceptions. Salinities were slightly higher in all three zones during the sam- pling on July 20, but river flow rate had not decreased from the previous sampling date. Zooplankton density had increased substantially in Zone 1, but had decreased by half in both Zones 2 and 3. A few fresh- water taxa contributed to the zoo- plankton only in Zone 1. Diversi- ty had increased only in Zone 1, and had fallen slightly in Zones 2 and 3. Arcella discoides was the only freshwater species to reach the dominance list, and it was in Zone 1. The ctenophore, Mnemiopsis mccradyi, reached the dominance list in both Zones 2 and 3, and should be considered as a possible cause for the decrease in zooplankton den- sities in these two zones. The species and taxa which most characterize the estuarine zooplank- ton community were also most often found in the dominance tables be- cause they contributed greatly to the densities in each zone and par- ticularly to those in Zones 2 and 3. These species and taxa forming the estuarine zooplankton community in San Antonio Bay are Acartia tonsa, Balanus sp . nauplii, Oithona colcar- va , Pseudodiaptomus coronatus , Para- calanus crassirostris , cyphonautes larvae of Membranipora sp., spionid larvae, polychaete larvae, and gas- tropod veligers. Acartia tonsa was usually very abundant, and is known to tolerate very low salinities (Conover 1956) . Even the flood could not displace it from being the domi- nant zooplankter. Only during the winter and spring with salinities above 20 parts per thousand was A. tonsa often replaced as the dominant taxon by Balanus sp. nauplii. Many of the typically estuarine species were replaced by species and taxa of freshwater origin during the flood (Table 3) . The most character- istic of these freshwater taxa were the freshwater calanoids Eurytemora affinis and several species of Dia- ptomus ; the freshwater cyclopoids Cyclops sp . , Eucyclops sp . , Apocy- clops panamensis and Microcyclops sp.; the cladocerans Moina micrura and Diaphanosoma brachyurum; the rotifers Brachionus quadridentatus , B. Calycif lorus and Platyias quad- ricornis; and the protozoan Arcella discoides . There were many other taxa of freshwater rotifers, clado- cerans, copepods , and insect larvae that entered the bay with floods and freshets, but most were found in low densities and frequencies. Most of these freshwater spe- cies are characteristic of backwater areas (Ward and Whipple 1959; Cooper 1967) rather than the open river it- self. These freshwater species' pop- ulations may have been dense locally, but when they were washed into the bay by the floods their densities were considerably lower than those of the estuarine zooplankters in- habiting the bay. The dilution and displacement of bay water by the fresh water of a flood creates a nat- ural dilution of the estuarine zoo- plankton, and when the diluting wa- ter has relatively few zooplankters the result is a reduction in the to- tal zooplankton density in the bay. This is what happened during the May flood. Diversity, however, was in- creased in the bay because of the 518 influx of freshwater species. The myriad of backwater localities along the tributaries allowed for many dif- ferent species' populations to flour- ish, and during the flood they were washed down the rivers and into the bay. Initially, more freshwater spe- cies and taxa were added to the sam- pling sites than estuarine species were displaced or killed. Diversity declined after this initial increase probably because most of the fresh- water zooplankton had already been carried down the river, and because flow rates declined so that fewer remaining plankters were carried in- to the bay. the May 1972 flood. Diversity ap- peared to be regulated considerably by the amounts and rates of river inflow (Figure 3). During the first four months the diversity trend fol- lowed the river flow rate but was one sampling delayed (time lag ef- fect) . From the beginning of the June flood through the October flood, this relationship was no longer found. In spite of the decrease in river flow rate during the last of the year, diversity in all zones also decreased. Much of this de- crease was due to the cold weather when many meroplankters are no long- er found in bay waters. It is evident that the zoo- plankton community in the bay was greatly changed by the flood and that the changes occurred within two weeks of the start of the flood, and probably much sooner. Re-estab- lishment of the typical estuarine zooplankton community depends sub- stantially on the reduction of riv- er flow rates, and after flow rates fall below freshet levels, it can still take two months to re-estab- lish the estuarine species in the upper bay. Only about one month was required to re-establish it in the lower and middle bay areas. In this specific case the east side of the bay was first supplied with high- er salinity water from Espiritu San- to Bay which was rich in estuarine zooplankton. Many tidal cycles and their attendant circulation patterns were required to re-establish the estuarine zooplankton along the west side of the bay. MULTIPLE FLOODS OF 1973 The species composition of the freshwater zooplankton that entered the bay with the river inflow was very much the same as found during The percentage of the diversity of each zone, contributed by taxa of freshwater origin, was greatly in- creased by the June and October floods (Figure 4) , and these percen- tages were much higher for Zone 1 than for Zones 2 and 3. Percentages contributed by freshwater taxa in Zones 2 and 3 were similar and they varied together more closely than with that of Zone 1 during the en- tire year. The total zooplankton density decreased an order of magnitude from the start of the year to the end, but it also decreased much lower at times between these end points (Figure 5). Total density showed an inverse rela- tionship to river flow rate. The June and October floods each caused a decline in total density of nearly two orders of magnitude which was never completely regained through the rest of the year. The recovery time, or time required for the density of a zone to re-establish its preflood level, appeared to be between two weeks and a month, i.e. between one and two sampling trips. The recov- ery time depended on tides, circu- lation patterns, spawning rates and periods, and temperature. 519 (OL * -3as/fui) MOIJ H3AIH I 1 0 in o lt3 o lo n n cm •- ^ VXV1 J° ON XI *J ■H 3 oo C o 1— 1 CO „ CO r~- CfN I— 1 oo a •H VJ 3 XI #* w co X » co PQ O ■H C o 4-1 c < V ~i c C/0 Ml CO c ci •l-l H CO U im •H •o lJ o •1-1 4-1 w M a N CO >» CO CO T3 oi o u PH a oo « CO H S-l a, o S o o N 1— 1 1+4 4H O S-l CU >i > U •H •H S-l C/J S-l CU (L) oo > CO •H S-l T3 (LI > > CO o T3 4J 1 O CO T— 1 X « 0J 4-> JS 4-> (-1 4-> CO •H s 3 x: CO 00 (LI a S-l o 4-4 i— i CO >> X ** CO T) r— (11 c^ ^J 1—1 -1 X 00 •H a Vj ■H 4-> S-l d 3 o ■o u »• w CO 0) CO 00 X m (Li 4-1 H C tu »* u >» S-l CO 0) m eu o ■H • d ac d 4J •H CO co (J4 CO "O 521 ABUNDANCE ZONE 1 ZONE 2 — ZONE 3 ■■•• o X LU > en F MAM 1973 Figure 5. Total zooplankton densities averaged for each zone in San Antonio Bay, Texas, during 1973, along with the 10-day average river flow rates for each sampling date. 522 After each flood the zooplank- ton did recover, but in each case the recovery was incomplete. Densi- ties were 10,000/m to 20,000/m be- fore the April flood ^ decreased to 2,000/m to 6,000/m during the flood and recovered to 4,000/m to 20,000/m afterwards. The June flood arrived soon after this recovery, and densities., declined again, this time to 400/.m to 800/m ~ Recovery to 4,000/m to 12,000/m occurred be- tween the two major flow periods of this flood, and much of these densi- ties were due to moderate populations of freshwater zooplankters . Zoo- plankton -density in Zone 1 fell to only 64/m after this second pulse of flood water. Equipment failure pre- vented sampling the other zones. After the flood, the densities re- covered again to 1, 800/m to 11,000 /m , just slightly lower than the preflood values. At the start of the October -flood the densities were about 850/m to 9,500/m , and they declined to 70/m at the end of the flood. Recovery after the flood was delayed in Zone 1, but it was rapid in Zones 2 and 3 with preflood densi- ties being attained within a month. to Zone 1 sooner and for a longer time than for the other zones which is reasonable considering Zone 1 is closest to the river mouth. The cumulative effects of the floods during 1973 appear to be those of temporarily increasing diversity and decreasing density. Increased diversity in the bay as a whole is logical with the addition of fresh- water taxa to those taxa already existing in the bay. Much of the decrease in density can be attrib- utable to the relatively low densi- ties of Balanus sp . nauplii in De- cember 1973 versus the same time the previous year. This is a result of stressing or killing the adult bar- nacles with the very low salinities which existed in the bay for such an extended period. Matthews et al. (1975) noted relatively low standing crops of phytoplankton from early October through December 1973 as com- pared with the other periods. This paucity of food could have resulted in the poor spawn among the surviving barnacles, and thus the lower densi- ties after the floods. Zooplankton of freshwater or- igin contributed greatly to the to- tal density of each zone during these floods. Their contributions during the April flood were relatively minor, reaching only 33 percent of the total density in Zone 1 and much less for those in Zones 2 and 3 (Fig- ure 6) . Their contributions during the June flood were much greater, reaching 97 percent for Zone 1 near the middle of the flood, and 68 per- cent and 35 percent for Zones 2 and 3 respectively. Similar levels of contribution were found for each zone during the October flood. Dur- ing all three floods, the freshwater taxa contributed a greater percentage CONCLUSIONS AND RECOMMENDATIONS Prolonged exposure of an es- tuary to fresh water such as was found during the floods in San Anto- nio Bay in 1973 may be considered damaging to the zooplankton and other fauna of the area on a temporary ba- sis. Typical estuarine fauna are replaced by freshwater fauna and to- tal zooplankton densities are usu- ally greatly reduced during each flood. Because the 1973 type of flooding occurs once in 100 years or less, and because its effects are rapidly erased by influx of organisms and zooplankton from neighboring 523 (01 x -39S/fUJ) my d3A,y (==J CD O «=> • — r~- its < < ° S ° rvi fJ rvi O en O CO I o CO I CD CO I I I I O Lf) O LO CNJ «— — u t-i o O 4-1 4-1 -o (0 11 0) oo 4-> «3 « l-i S-l 11 > 3 RJ o i— 1 tfl 4-1 (LI •H U 4-1 1) ■H > I/) •H c J-l 0J -a 1) oo a «) o S-l 4-> 11 j»5 > a «3 « >— 1 S* & nj s * 4H = TD * M 3 H S O c o 4-> c < a 14 00 u 0u C oo el SO SlAISINV9clO Md lN33H3d 1) a S e O nj 1) N w u 3 X! £ OO o u tn 1> U 524 bays, there is no need to take pre- ventive action. The seasonal timing of floods can have important consequences. The occurrence of a flood when larvae of economically important species are in the zooplankton could signifi- cantly reduce future harvests in the bay by displacing or killing these larvae. At this time the im- portance of the influx of organisms and zooplankton from neighboring bays can not be overstated. Re- cruitment from these bays can assist in re-establishing these economically important species. Thus, it is nec- essary to define the circulation pat- terns between estuaries and to real- ize their interdependence so as not to delude ourselves into relinquish- ing one estuarine area to pollution as though it were an entity unto itself. Biology of Acartia clausi and A. tonsa . Bull. Bingham Ocean- ogr. Coll. 15:156-233; 1956. Cooper, D.C. Ecological parameters concerning the zooplankton com- munity of the San Antonio Estua- rine System. Austin, TX: Univ. of Texas; 1967; 124p. Thesis. Hopkins, T.L. The plankton of the St. Andrew Bay System, Florida. Publ. Inst. Mar. Sci. Univ. Tex. 11:12-64; 1966. Matthews, G.A. ; Marcin, C.A.; Clem- ents, G.L. A plankton and ben- thos survey of the San Anto- nio Bay System, March 1972 to July 1974. Tex. Parks and Dept. Coastal Fish. Div. Final Report to the Tex. Water Devel. Board, 1975; 76p. LITERATURE CITED Conover, R.J. Oceanography of Long Island Sound, 1952-1954. VI Ward, H.B.; Whipple, C.G. Freshwater biology. 2nd Ed. Edmondson, W.T. ed. New York: John Wiley and Sons, Inc. 1975; 1248p. 525 * U.S. GOVERNMENT PRINTING OFFICE 1981-775-163 Portland, Ore. ' 1 1 Twin 1 y \r t Denver. Colo. 1© Albuquerque, N. M. Cities, Minn. Dston, Mass. . Atlanta, Ga * o 0® LEGEND Headquarters • Office of Biological Services, Washington, D.C. National Coastal Ecosystems Team, Slidell. La. Regional Offices U.S. FISH AND WILDLIFE SERVICE REGIONAL OFFICES REGION 1 Regional Director U.S. Fish and Wildlife Service Lloyd Five Hundred Building, Suite 500 N.E. 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