[From the U.S. Government Printing Office, www.gpo.gov]
Pollution Ecology of Winyah Bay, SC: * ~~Characterization of the Estuary and Potential Impacts of Petroleum I ~Dennis M. Allen William K. Michener,' and Stephen E. Stancyk ......v..~-g TD ~ ~ ~ Boo~~~~~~~~.~ ~~Uniest of So ut C aoln-S e ilPbiainN. 84-1 3 Property of CSC I POLLUTION ECOLOGY OF WINYAH BAY, SC: CHARACTERIZATION OF THE ESTUARY AND POTENTIAL IMPACTS OF PETROLEUM I Dennis M. Allen, William K. Michener, and Stephen E. Stancyk I Belle W. Baruch Institute for Marine Biology and Coastal Research University of South Carolina ~~~~~~~I ~Columbia, SC 29208 | Final Report for Phases II and III March 1984 Funds provided by the National Oceanographic and Atmospheric Administration U.S. Dept. of Commerce, through the Coastal Energy Impact Program (Grant No. NA-81-AA-D-CZ096). Awarded through the Division of Natural Resources, Governor's Office, State of South Carolina. 1 .. .DEPARTMENT OF COMMERCE NOAA �_COASIAL SERVICES CENTER '234 SOUTH HOBSON AVENUE I 2hARLESTON, SC 29405-2413 This report should be cited: Allen, D.M., W.K. Michener, and S.E. Stancyk, Eds., 1984. Pollution Ecology of Winyah Bay, SC: Characterization of the Estuary and Potential Impacts of Petroleum. Baruch Institute Special Publication No. 84-1 5, 271pp. _i o- o en b > Of .~~~~1~ TABLE OF CONTENTS I LIST OF TABLES v LIST OF FIGURES vii ACKNOWLEDGEMENTS ix EXECUTIVE SUMMARY x CHAPTER 1. ESTUARINE ECOLOGY AND THE SCOPE OF THE STUDY 1-1 by D.M. Allen and W.K. Michener CHAPTER 2. THE STUDY AREA 2-1 by D.M. Allen and W.K. Michener A. Winyah Bay Estuary 2-1 B. Sampling Locations 2-5 CHAPTER 3. METHODS AND MATERIALS 3-1 by D.M. Allen and W.K. Michener A. Extensive Series 3-6 B. Intensive Series 3-8 C. 48 hour Zooplankton Series 3-9 D. Special Multi-level Epibenthos Series 3-10 E. Special Chemistry Transect Series 3-12 CHAPTER 4. PHYSICAL-CHEMICAL CHARACTERISTICS 4-1 by W.K. Michener Introduction 4-1 Section I 4-2 Water Temperature 4-4 Salinity 4-6 Secchi Disk Visability 4-8 Phosphorus 4-10 Nitrogen 4-12 Chlorophyll a, Phaeopigments, and Organic Carbon 4-16 Section II 4-21 Water Temperature 4-22 Salinity 4-23 Phosphorus 4-25 Nitrogen 4-27 Chlorophyll a, Phaeopigments, and Organic Carbon 4-29 Section III 4-31 ii TABLE OF CONTENTS (CONT.) CHAPTER 5. ZOOPLANKTON 5-1 by N. Alon and S.E. Stancyk I. Taxonomic Diversity 5-5 II. Total Zooplankton 5-6 III. Dominant Zooplankton Categories 5-13 IV. Copepods A. Acartia tonsa 5-19 B. Eurytemora affinis 5-20 C. Parvocalanus crassirostris 5-23 D. Pseudodiaptomus coronatus 5-24 E. Euterpina acutifrons 5-26 F. Oithona colcarva 5-27 G. Halicyclops spp. 5-28 V. Meroplankton A. Barnacle larvae 5-28 B. Crab zoeae 5-30 C. Polychaete larvae 5-30 D. Molluscan larvae 5-31 CHAPTER 6. MOTILE EPIBENTHOS 6-1 by D.M. Allen A. Mysids 6-3 B. Amphipods 6-14 C. Isopods 6-17 D. Cumaceans 6-19 E. Decapod Shrimps: adults 6-20 F. Decapod Shrimps: larvae 6-22 G. Decapod Shrimps: postlarval penaeids 6-24 H. Decapod crabs: megalopae 6-27 I. Fishes: eggs 6-29 J. Fishes: larvae 6-30 K. Chaetognaths 6-36 L. Medusae and ctenophores 6-37 M. Total organisms 6-38 N. Sampling considerations 6-42 O. Summary 6-46 CHAPTER 7. CHARACTERIZATION OF WINYAH BAY AND POTENTIAL IMPACTS OF CHRONIC AND ACUTE OIL POLLUTION 7-1 by W.K. Michener and D.M. Allen Fates and Impacts of Oil in the Marine Environment: A Survey of Recent Literature 7-3 ~~~~~~~~~I ~~iii TABLE OF CONTENTS (CONT.) Ecological Consequences of Oil Discharge into Winyah Bay 7-10 The Upper Bay 7-12 Potential Impacts in the Upper Bay 7-15 The Middle Bay 7-19 Potential Impacts in the Middle Bay 7-22 The Lower Bay 7-24 Potential Impacts in the Lower Bay 7-26 LITERATURE CITED L-1 APPENDICES Key to Appendices I-VII A-1 Appendix I .A-2 Appendix II A-16 Appendix III A-26 Appendix IV A-47 Appendix V A-63 Appendix VI A-71 Appendix VII A-79 iv LIST OF TABLES CHAPTER 2 THE STUDY AREA PAGE 2-1 Locations, geomorphological characteristics, and salinity range for 14 stations in Winyah Bay . . 2-3 CHAPTER 3 THE SAMPLING PROGRAM: METHODS AND MATERIALS 3-1 Sampling dates for Extensive and Intensive Series. . 3-7 3-2 Sampling dates during the Special Chemistry Transect Series . . . . . . . . . . . . . . . . . .3-13 CHAPTER 5 ZOOPLANKTON 5-1 Relative abundance of three dominant zooplankton categories on the Extensive Series cruises . . . . . 5-3 5-2 Relative abundance of three dominant zooplankton categories on the Intensive Series cruises . . . . . 5-4 5-3 Comparative abundance of zooplankton from surface and bottom on the 48 hour sampling . . . . . . . . .5-15 CHAPTER 6 MOTILE EPIBENTHOS 6-1 Mean number of organisms on all Extensive Series cruises . . . . . . . . . . . . . . . . . . . . . . 6-6 6-2 Mean number of organisms at all 11 Extensive Series and 3 Intensive Series stations . . . . . . . 6-7 6-3 Percentage of total catch for each taxa on Special MN sampling . . . . . . . . . . . . . . . .6-12 6-4 Summary of occurrence of taxonomic groups in a variety of sampling gear during the Special MN sampling . . . . . . . . . . . . . . . . . . . . . .6-13 6-5 List of fishes represented by larvae or postlarvae in epibenthic sled collections . . . . . . . . . . .6-32 6-6 Comparison of total organism densities in different gear types on the Special MN sampling . . . . . . .6-43 6-7 Comparison of total organism densities at different tidal stages on Special MN sampling . . . . . . . .6-45 v LIST OF TABLES (CONT.) CHAPTER 7 ECOLOGY OF WINYAH BAY AND POTENTIAL IMPACTS OF PAGE CHRONIC AND ACUTE OIL SPILLAGE 7-1 Lethal concentrations of crude and No. 2 fuel oil . .7-5 7-2 The impacts of sustained low concentrations of No. 2 fuel oil on principal trophic components, species, and nutrients in the MERL microcosms .....7-7 vi LIST OF FIGURES CHAPTER 2 THE STUDY AREA PAGE 2-1 Location of sampling sites in Winyah Bay . . . . . . 2-2 CHAPTER 4 PHYSICAL-CHEMICAL CHARACTERISTICS 4-1 Surface salinity regime at three sites (MN, MS, US) during the Intensive Series . . . . . . . . . . . . 4-7 4-2 Composite plot of total nitrogen and dissolved nitrogen fractions vs. salinity . . . . . . . . . . 4-14 4-3 Concentrations of chlorophyll a vs. salinity . . . . 4-18 4-4 Composite plot of chlorophyll a and phaeopigment concentrations vs. salinity . . . . . . . . . . . . 4-20 4-5 Salinity of surface and bottom water during the 48 hour:sampling . . . . . . . . . . . . . . . . . 4-24 4-6 Orthophosphate concentrations of surface and bottom water during the 48 hour sampling . . . . . . 4-26 4-7 Nitrate-nitrite nitrogen concentrations of surface and bottom water during the 48 hour sampling . . . . 4-28 4-8 Chlorophyll a concentrations of surface and bottom water during the 48 hour sampling . . . . . . 4-30 CHAPTER 5 ZOOPLANKTON 5-1 Mean densities of total organisms at all 11 Extensive Series stations . . . . . . . . . . . . . 5-7 5-2 Mean densities of total organisms on each Extensive Series cruise ................... 5-9 5-3 Mean densities of total organisms at US during the Intensive Series (surface and bottom) . . . . . . . 5-10 5-4 Mean densities of total organisms at MS during this Intensive Series (surface and bottom) . . . . . . . 5-11 5-5 Mean densities of total organisms at MN during the Intensive Series (surface and bottom) . . . . . . . 5-12 5-6 Mean densities of total zooplankton at the surface and bottom during the 48 hour sampling . . . . . . . 5-14 vii 5-7 Percent composition at all 11 Extensive Series . . . 5-17 5-8 Percent composition on each Extensive Series cruise ............................... 5-18 5-9 Mean densities of all Acartia tonsa at the surface and bottom during the 48 hour sampling . . . . . . . . 5-21 5-10 Mean densities of Parvocalanus crassirostris at the surface and bottom during the 48 hour sampling . . . . 5-25 CHAPTER 6 MOTILE EPIBENTHOS 6-1 Percent composition of major taxa on all Extensive Series cruises ....................6-4 6-2 Percent composition of major taxa at all 11 Extensive Series stations . . . . . . . . . . . . . . . . . . . 6-9 6-3 Mean densities of total epibenthos and mysids on the Intensive Series cruises . . . . . . . . . . . . . . . 6-11 6-4 Mean densities of amphipods and crab megalopae on the Intensive Series cruises . . . . . . . . . . . . . . . 6-16 6-5 Mean densities of shrimp larvae and fish larvae on the Intensive Series cruises . . . . . . . ... . . . . . 6-25 6-6 Mean densities of total organisms on all Extensive Series cruises . . . . . . . . . . . . . . . . . . . . 6-39 6-7 Mean densities of total organisms at all 11 Extensive Series stations . . . . . . . . . . . . . . . . . . . 6-41 viii ACKNOWLEDGEMENTS A study of this magnitude would not have been 'possible without the help of dozens of individuals who were dedicated to their work. The editors would like to express their special thanks to research specialists Bruce C. Lampright, T. Lance Ferrell, and Elizabeth Haskin for their efforts in making field measurements and processing zooplankton and epibenthic sled collections. Noel Alon also invested a great deal of time in collecting and processing samples and analyzing the zooplankton data. Beth Thomas was a regular member of the sampling team and was involved with data management and manuscript preparation throughout the study. William Johnson processed water samples and aided in the development of the nutrient study. We also thank Wendy Allen, Doug Baughman, Lee Ann Clements, Mark Luckenbach, and Tom Wolaver for assistance in collecting samples, often under adverse conditions. D. Lynn Barker, Steve Hutchinson, Marvin Marozas, Robert McLaughlin, and Bobbie McCutchen contributed their time and expertise, especially during the analysis of collections and data in the laboratory. Don Caton and Paul Johnson are acknowledged for their keeping trucks, boats, and sampling equipment in operating condition. We thank Yvonne Coakley and Shelley P. Elmore for typing this report, and F. John Vernberg and Virginia Smith for help in administrating this grant. This study was funded by the National Oceanographic and Atmospheric Administration, U.S. Dept. of Commerce, through the Coastal Energy Impact Program (grant no. NA-81-AA-D-CZ096). We thank Michael Rowe and Trish Jerman of the Division of Natural Resources, Governor's Office, State of South Carolina for much help and encouragement in conducting this study. ix EXECUTIVE SUMMARY 1. Phases II and III of our study of the Winyah Bay Estuary consis- ted of a series of 33 sampling excursions between September 1981 and September 1982 during which physical, chemical, and biological mea- surements were made along the salinity gradient. Data were obtained from 14 locations within the estuary. The study was an expansion of phase I of an investigation to characterize Winyah Bay and assess the potential impacts of petroleum pollution on the ecosystem. 2. Analyses of water samples indicated that concentrations of all nitrogen compounds (NO3, NO2, NH4, TN) were consistently highest in the upper bay and decreased as a function of increasing salinity to- ward the ocean. A similar pattern was observed for phosphorus com- pounds. Concentrations were highest in winter when riverine inputs were greatest and utilization by phytoplankton was lowest. Previous studies have demonstrated that concentrations of nutrients in estuar- ine water are reduced in the presence of oil. Oiled sediments most likely affect rates of mineralization. 3. Phytoplankton production was lowest in the rivers and highest in the middle bay. A distinct seasonal trend with maximum phytoplankton activity in summer and minimum in winter was observed. Planktonic diatoms and dinoflagellates are generally less abundant in low salin- ity areas of estuaries, and the flushing activity of the freshwater input limits local populations. High chlorophyll concentrations in the middle bay are probably related to high nutrient densities and circulation patterns which encourage retention and production. The source of phytoplankton in the lower bay was the ocean. Effects of oil on phytoplankton are generally minimal once soluble (toxic) fractions leave the water column; however, indirect effects as a re- sult of changes in nutrient availability and herbivore grazing pres- sure may have long term repercussions for the ecosystem. 4. Copepods were the dominant zooplankters throughout the estuary during all seasons. Maximum densities in excess of 10,000 individu- als per cubic meter occurred during the warm months. Acartia tonsa, the most abundant species, dominated intermediate salinity areas. Other major species originated from the ocean and became more abun- dant in the middle bay as salinities increased. High salinity (mar- ine) copepods were almost never present in the upper bay and several species of freshwater copepods rarely occurred seaward of the upper bay. Although copepods including A. tonsa may be eliminated by sol- uble toxic chemicals during an oil spill, they appear to be relatively tolerant of petroleum compounds in the water column and can quickly repopulate an area. Responses of copepod populations to oil pollution are highly variable and long term effects are not well understood. 3 ~~~5. Temporary members of the zooplankton including larvae of crustaceans, polychaetes, mollusks, and fishes were the most important constituents of the community during the warm months. Highest densities were near the ocean and many species were confined to high salinity, lower bay areas. Crab zoeae and barnacle larvae were sometimes abundant in the upper bay. Most of these developmental stages only occur for periods of days or weeks and I ~ ~~~may represent the entire year's reproductive effort of short lived estuarine species. Larval stages of invertebrates and fishes are often more sensitive to oil pollution than adults. A spill during aperiod of peak reproduction is likely to have major and long lasting effects on certain populations. 6. Amphipods, mysids, cumaceans, isopods and other small crusta- ceans which live on or near the bottom were widely distributed throughout the estuary, but highest diversity was near the ocean and highest densities were usually in the middle bay. Amphipod populations were consistently high in some rivers. Permanent 3 ~ ~~~members of the motile epibenthos are particularly susceptible to chronic oil pollution since oil accumulates at the sediment surface where these animals feed and reproduce. Long term reductions in I ~ ~~~these populations would result in loss of primary foods for juve- nile fishes. 7. Shrimp, crab, and fish larvae comprising the motile epibenthos occurred throughout Winyah Bay, and their abundance was highly variable. Postlarval penaeid shrimp and dozens of commercially important species of larval fishes were most abundant during the warm months, especially in the middle bay. Relatively low densities of epibenthic larvae utilized upper estuary habitats. Due to patchy distribution, high motility, and preference for shallow marsh fringes and creeks, densities of larvae in epibenthic sled I ~ ~~~collections were large underestimates of the populations utilizing the estuary as a nursery area. Since most of these forms feed at the bottom, they would be very susceptible to post-spill or U ~ ~~~chronic oil pollution which results in oiled sediments. Fisheries would be adversely affected over long periods as a result of the destruction of larval forms and nursery habitat~s. 1 ~~~8. A major spill in the upper bay would have a less severe immediate impact on the organisms in the water column than a similar spill in the middle or lower bay; however, residuals from an upper bay spill would probably have a more severe long term effect. High densities of fine sediment particles which characterize the upper regiion of Winyah Bay would result in the rapid incorporation of oil into the sediments. Similarly, chronic discharges of relatively I ~ ~~~low concentrations of petroleum in the Sampit River would also result in oiled sediments. Microbial decomposition rates woulC probably not be sufficient to inactivate oiled sediments before they were redistributed by currents or runoff from spoil areas to I ~~~~~~~~~~~xi 9. Circulation patterns within the estuary indicate that Mud ' Bay and other shallow backish areas in the middle bay would be a final destination of spilled oil (slick) and ailed sediments originating from an accident or chronic imputs in the upper bay. Since this region is also the location of highest overall phyto- plankton, zooplankton, and larval fish production, severe ecological consequences would be inevitable. The presence of large intertidal marshes, vast shallow fine grained mudflats, and creeks whichI exchange water with the pristine North Inlet system suggest that a spill or the accumulation of polluted sediments in the middle bay would have the most severe impacts on the ecosystem as aI whole. 10. Although the probability of a major oil spill in Winyah BayI is not high, it is likely that one or more significant spills would occur during the lifetime of a refinery. A major spill would have a devastating effect on the ecosystem. Regardless of whether or not a major spill occurs, chronic discharges bf petro- leum and refined products into the water and air would be allowed by law and would continue as long as the refinery was in operation. The presence of toxic petrochemicals in the refinery effluent, the3 accumulation of an oily sludge on the bottom, and the reduction of dissolved oxygen levels in the Sanmpit River will contribute to the degeneration, displacement, or elimination of plant and animal populations in the Sampit River and, eventually, other sections ofI Winyah Bay. g ~~~~CHAPTER 1. ESTUARINE ECOLOGY AND THE SCOPE OF THE STUDY. 3 ~~~~Coastal areas where significant amounts of freshwater runoff meet the sea are known as estuaries. Formally defined, an estuary 3 ~~~is a semi-enclosed coastal basin which has an open connection to the ocean and within which saltwater is measurably diluted by 3 ~~~freshwater. Major fluctuations in the volume of freshwater inflow coupled with more regular variations in tidal amplitude result in I ~~~complex circulation patterns. Nutrients, organic materials, and 3 ~~~sediments introduced from both the rivers and the ocean are dis- tributed according to highly variable and complex current patterns. 3 ~~~Patterns are difficult to describe because of the dynamic nature of the system and restrictions on the number of measurements that can 3 ~~~be taken within any one combination of space and time. The motility of animals renders patterns of organism distribution within the I ~~~estuary more difficult to describe than those for passive materials. 3 ~~~Despite the dynamic character of an estuary such as Winyah Bay, there are distinct relationships between constituents of a parcel of 3 ~~~water and its salinity. Changes in nutrient concentrations and small organism abundance can often be explained by changes in salinity. 3 ~~~These relationships enable us to characterize an estuary in sufficient detail to be able to assess the potential impacts of pertubations 5 ~~~such as oil pollution. This study was developed: (1) to establish baseline information on specific physical, chemical, and biological characteristics of the5 Winyah Bay Estuary, (2) to determine the associations between the abiotic and biotic characteristics of the system, and (3) to assessI the potential impacts of energy related development on organisms which inhabit Winyah Bay. The study represents the second and third3 phases of a three year field oriented research program. Results of the first phase were published in a report entitled: Ecology of I Winyah Bay, SC and Potential Impacts of Energy Development (Allen et al., 1982). In that report, we described sampling programs and presented results of studies at No Man's Friend and South Jones3 Creeks. During the first phase, we also made collections along the axis of W~inyah Bay. The second phase of our program involved an5 expansion of the initial set of sampling sites along the salinity gradient in Winyah Bay. The original series of six stations were I sampled over a 28 month period, with five additional sites being added in the second year. At each sampling location, a complete set of physical measurements, water samples, and biological collections were made. Chemical analyses were conducted to determine nutrient concentrations,. and chlorophyll was measured to determine the density3 of microscopic plants (phytoplankton). Microscopic animals were collected in the water column with fine mesh nets and somewhat larger,5 but still less than half inch long, organisms were collected near the bottom. The catch included the developmental stages of almostI all conmmercially and recreationally important shrimps, crabs, an' 5 ~~~fishes as well as the small organisms upon which adults of these species prey. The third phase of the project consisted of a series of short term field studies designed to investigate the magnitude of variability in physical, chemical, and biological components measured at one 16ea- � ~~~tion over one or more tidal cycles. The techniques used to collect and process samples during the I ~~~second and third phases of this study were, in most cases, identical to 5 ~~~those used in the first phase. In our first report, we provided many detailed descriptions and diagrams of the organisms that were 5 ~~~collected in fine mesh nets. Only general information is used to preface the results of the analyses in this report. We hope that 5 ~~~the interested reader will review and consult the appropriate section � ~~~of the previous report. During the second and third phases of our study we made approximately 3 ~~~280 sets of physical measurements, 570 zooplankton collections, and 480 epibenthic sled collections. Many hours were involved in the field 3 ~~~collection, laboratory processing, and subsequent computer-aided 5 ~~~analysis of each collection. Although hundreds of hours of effort have already been spent on data management and statistical analysis of 5 ~~~this huge data set, the treatment of the results at this time is con- sidered preliminary. This report contains several chapters which I ~~~describe ge neral trends which were determined by tabular and graphical comparisons of mean values. The final chapter presents a synthesis of the physical, chemical, and biological trends established during the 1-3 two year study. It is important f or the reader to recognize that3 only general patterns and associations are described in this report and that sophisticated statistical techniques are being developed to explore these interactions in more detail. The results of these5 analyses will constitute formal scientific publications during the next several years. The vast siz~e of Winyah Bay and the large variability charac-g teristic of all measured components places limitations on the degree to which the estuary can be studied. The network of 14 regular stations was established to generate information on the differences between major habitat types, yet at least that many more different habitats occur within the system. We concentrated on subtidal habitats repre- senting the most dominant bottom types along the salinity gradient. Productive intertidal and shallow subtidal habitats were not sampled.1 With the amount of technical help available, it was not possible to study benthic, fouling, or fish communities within Winyah Bay. Our focus was on the abundant small organisms which are close to the base of the estuarine food web. Even with these restrictions, theI number of collections that we were able to make was limited by the1 rate at which we could process them in the laboratory. Nevertheless, sufficient information was generated to develop a description of the spatial and seasonal distributions of key zooplankton and motile3 epibenthic taxa. Several special short term studies were conducted to determine vertical distribution or patchiness near the bottom and9 to protride insight into the behavior of these organisms relative to 1-4 3 ~~~tidal currents and salinity regimes. The first report included a thorough review of scientific liter- 3 ~~ature dealing with the effects of petroleum and refined fractions on estuarine organisms. Rather than repeat this effort, we have devel- oped a final chapter in which we integrate our understanding of the 3 ~~physical, chemical, and biological characteristics of Winyah Bay with the known effects of oil pollution. Chronic and acute effects I ~~on the biota are assessed for the upper, middle, and lower bay. 5 ~~Particular emphasis is placed on effects on early life stages of fishes, crabs, and shrimps which utilize estuarine areas for nursery f ~~grounds. We believe that this is a realistic interpretation of the situation and hope that it will be useful in evaluating society's I ~~impact on Winyah Bay and determining the future of this estuary. I~~~~~~~~~~~~~- CHAPTER 2. THE STUDY AREA A. Winyah Bay Estuary The area considered in the present study includes the waterways and marshes which comprise Winyah Bay, South Carolina. Winyah Bay is one of the major estuarine ecosystems in the southeastern United States. The axis of Winyah Bay is roughly oriented in a northwest- southeast direction (Fig. 2-1). The estuary is narrowest near its confluence with the ocean (0.8 miles) and widest in the center (4.2 miles). At the upper end of the bay where the two major rivers converge, the width is about 1.2 miles. Prominant features of Winyah Bay include the long rock jetties which project more than a mile into the ocean from North and South Islands, several large islands within the bay, and a large shallow midsection known as Mud Bay. Winyah Bay has a mean depth of only 15 ft. (4.2 m) and many hectares of open waterways are less than 6 ft. (2 m) in depth. A 27 ft. (8.2 m) ship channel runs along the axis of the bay from the end of the jetties to Georgetown Harbor. Details of the bathymetry of Winyah Bay are available from Coast and Geodetic Survey navigation map No. 787 and several U.S. Army Corps of Engineers documents (e.g. Trawle, 1969). The entire Winyah Bay watershed is approximately 18,000 square miles (sq. mi.). Four major rivers drain into the system. More 2-1 --.. ~ J. .e, /.- R iver .:~.' .~ . k - Debid Georgetown 3 . DebIsland .I,~~ |~B W. Barch / - k''Q' Hobeaw B a ron y I WINYAN < North Inlet BAY 3 ; 015 Mud Bay,/, n SB eBI ..'nx~ � ATLANTIC Yaw.e...A dille 'C"entnr WieOCEAN ArvandfI A _ .. .> t *MN a, :f NtNrth e i * ante* km Figure 2-1. Location of sampling sites in Winyah Bay, SC. No Man's Friend (NMF) and South Jones (SJ) Creeks were the major study areas for Phase I of the study. Fourteen other stations were sampled during Phases II and III. They are described in Chapter 2 of this report. 2-2 Table 2-1. Locations, geomorphological characteristics, and salinity range for 14 stations in Winyah Bay which were sampled between August 1980 and September 1982. STATION LOCATION DEPTH (METERS) SEDIMENT SALINITY RANGE ABBREVIATION (LAT. - LONG.) AT MLW TYPE ( /oo) PR 330 21' 44" N 6.2 Firm Mud/Clay 0-11.7 790 20' 18" W SR 330 21' 28" N 8.0 Soft Mud 0-19.3 79� 17' 10" W PD 330 22' 29" N 3.0 Firm Mud/Clay 0-14.0 790 15' 40" W WR . 330 20' 30" N 9.5 Firm Mud/Clay 0-12.4 790 14' 45" W US 330 20' 40" N 6.4 Sandy Mud 0-17.3 790 16' 40" N BI 330 18' 42" N 6.7 Sandy Mud 0-22.0 790 16' 57" W TA 330 17' 40" N 1.0 Mud 0-17.7 790 15' 20" W PS 330 17' 30" N 0.8 Soft Mud 0-23.6 790 13' 28" W MS 330 16' 20" N 5.0 Sandy Mud 2.7-32.4 790 14' 22" W TC 330 17' 0" N 4.2 Sandy Mud 0-23.4 790 13' 40" W EP 330 16' 7" N 4.5 Sandy Mud 2.0-30.6 79� 16' 17" W MB 330 15' 28" N 3.9 Muddy Sand 1.8-31.7 790 13' 16" W And Shell SB 330 14' 36" N 4.2 Sand And Shell 3.8-33.9 790 11' 40" W MN 330 12' 6" N 3.6 Sand And Shell 21.5-35.3 79� 11' 17" W 2-3 than 16,000 sq. mi. of this drainage area is associated with the Pee Dee-Yadkin River system which originates in the Blue Ridge Mountain area of North Carolina. Water from this area flows across the piedmont region of both North and South Carolina, over the coastal plain of eastern South Carolina,and into Winyah Bay through the Pee Dee River. The Waccamaw River also receives water from the Pee Dee as the poorly defined, shallow, wide, swampy waterways merge upstream of the Highway 17 bridges. The Black and Sampit Rivers drain much smaller watersheds. Other characteristics of these watersheds are given by the Conservation Foundation (1980). According to Johnson (1972), the freshwater input to Winyah Bay Estuary ranges from 2000 to about 100,000 cubic feet per second (cfs), and mean runoff is approximately 15,000 cfs. Superimposed on this unidirectional freshwater flow toward the ocean is the regular semi-diurnal tidal pattern. Mean tidal amplitude is on the order of 4.6 ft. at the ocean end of Winyah Bay and 3.3 ft. at the Sampit River (5.4 ft. and 3.9 ft. on spring tides, respectively; Trawle, 1969). A salt wedge effect occurs as heavier salt water moves upestuary along the bottom with a flooding tide even though the overlying freshwater may be flowing toward the ocean. During periods of low freshwater inflow, flooding tides move salt water more than 15 miles upstream of the Highway 17 bridges, but under average river flow, the penetration is usually within a mile of the bridges. Differences between surface and bottom salinities during these periods may be more than 2. ppt. Corps of Engineers (Trawle, 1969) measurements indicate that while surface waters are usually 29-32 2-4 ppt near the ocean entrance during most flow conditions, surface salinities in Georgetown Harbor range from about 0-10 ppt. Salinity patterns in the mixing zone between these ends of the system are highly variable as a result of changing freshwater inflow, tidal amplitude, wind conditions, and bottom topography. Further information on the hydrography of Winyah Bay is available in Trawle (1969), Johnson (1970), and Bloomer (1973). Almost the entire shore of Winyah Bay is vegetated by marshes. Approximately 31,867 acres or 12,747 hectares of marsh are associated with this estuary. More than 77% of these marshes are regularly flushed through tidal action; the remaining 13% are impounded (Tiner, 1977). Some 80% of the marshes are vegetated by freshwater plants while most of the other 20% is inhabited by the brackish water grass (Spartina cynosuroides) and black rush (Juncus roemerianus). Of the 17 estuarine systems in South Carolina, Winyah Bay is most important in terms of freshwater marshes. In fact, about 35% of the state's freshwater marshlands occur here (Tiner, 1977). Rela- tively small stands of salt marsh cordgrass (Spartinia alterniflora) occur near the entrance of Winyah Bay, and a narrow band occurs adjacent to major waterways upstream to the middle bay. B. Sampling Locations Phases II and III of the Winyah Bay Study elucidated spatial and temporal patterns of the physical, chemical, and biological components of the estuary. A total of 14 sampling sites were visited on a regular basis. Their locations are shown in Figure 2-1. 2-5 Station location (latitude-longitude), depth, sediment type and salinity range are given in Table 2-1. Additional information on salinity patterns is presented in Chapter IV. The Pennyroyal Creek (PR) station was located in the Sampit River several hundred meters downstream of the confluence with Pennyroyal Creek. Tows were made parallel to the marsh shoreline on the south side of the axis of the river. The bottom was relatively flat and composed of firm muds and clays. Current velocities were slow to moderate, but detrital accumulations on the bottom were low. Salinities were generally less that% 5 ppt, but values to 12 ppt were recorded. There were no significant differences between surface and bottom salinities on any cruise. The Sampit River (SR) station was downstream of the Highway 17 bridge and adjacent to the SC Ports Authority Terminal. Measure- ments were made at the south side of the turning basin and sled tows were along the ship channel toward the mouth of the 'river. Sediments were soft muds, and currents were generally moderate to slow. Salinities ranged from 0 to 19 ppt on the bottom, and bottom salinities were up to 10 ppt higher than surface values. The Pee Dee River (PD) station was located approximately 1.3 km north (upstream) of the Highway 17 bridge. Water column measurements were made near mid channel. This area was the shallowest of the upestuary stations, and the bottom was characterized by high concentrations of marsh and terrestrial debris. Current velocities were moderate. Salinities were similar to those at other river 2-6 stations; bottom salinities reached a maximum of 14 ppt. Surface and bottom values did not differ by more than 5 ppt on any cruise. The Waccamaw River (WR) station was also situated about 1.3 km north of the Highway 17 bridge. Samples were collected near mid- channel in a large depression or basin which was more than 10 meters deep. The mud-clay bottom was usually free of organic detritus. Salinities were lower than those at PD on most cruises. Maximum bottom salinity was about 12 ppt and surface-bottom differences were less than 6 ppt. The Upper Station (US) was located in Winyah Bay on the eastern side of the ship channel just downstream of the mouth of the Sampit River. Water samples were collected upstream of navigation marker "28", and sled tows were parallel to the channel upstream of this location. Current velocities in this area were stronger than at any of the river stations. The bottom was relatively hard. Salinity regimes were similar to the SR station with distinct stratification apparent during most cruises. The Belle Isle(BI) sampling site was on the eastern side of the ship channel just upstream of the point where the channel curves to the southeast at Frazier Point. Water samples were taken near marker "24" and tows were made between markers "24" and "26". Moderate to strorg currents and a hard clean bottom were typical. Salinities at the bottom ranged from 0 to 22 ppt and surface values were up to 10 ppt lower than bottom values on some cruises. 2-7 Thousand Acre (TA) station was situated adjacent to the western creek draining Thousand Acre marsh on Hobcaw Barony. This shallow soft bottom area usually had high accumulations of marsh detritus. Currents were low to moderate. Salinities were as variable between cruises as the other upestuary stations, but no significant stratification was apparent. Bottom values ranged from 0 to 18 ppt. Pumpkinseed (PS) station was located in Mud Bay about 1 km west of the mouth of No Man's Friend Creek. The station was in shallow water at least 100 m from the eastern shore of the Marsh Islands. The sediment and current characteristics were similar to those at TA, but salinities were somewhat higher. The range at PS was from 0 to 24 ppt. No differences between surface and bottom salinities were observed. Middle station (MS) was located on the eastern side of the ship channel near marker "20". Water samples were taken near the marker and net tows were toward marker "18". The sediment was a hard sandy mud, but detrital accumulations were often high on this side of the channel.. Salinities ranged from 8 to 32 ppt on the bottom, but surface salinities were always much lower, sometimes by as much as 20 ppt. The Cut (TC) is a northwest-southeast oriented channel which runs between the Marsh Islands. The channel lies between Mud Bay and the ship channel. Water column measurements were made midchannel where currents were moderate. Sediments were firm and detrital accumulations were low. Salinities ranged from 0 to 23 ppt on the 2-8 bottom and differences between top and bottom were less than 4 ppt. The Esterville Plantation (EP) station was located in the western channel just above the Intracoastal Waterway channel which connects Winyah Bay and the Santee System. Collections were made about midway between the mainland at Esterville Plantation and the large marsh island. The bottom was firm sand mud, and moderate to strong currents limited detrital accumulations in this area. Salinity ranges for both surface and bottom were from 2 to about 26 ppt. Bottom salinities were sometimes up to 20 ppt greater than at the surface. The Mud Bay (MB) sampling site was on the eastern side of the ship channel across the channel from marker "17". Water samples were taken at the edge of the channel where current velocities were moderate to strong. The bottom was sandy and firm with little detritus. Salinities ranged from 4 to 33 ppt and differences between surface and bottom were as large as 11 ppt. Shell Bank (SB) station was located between the shore of North Island and the small spoil islands east of the ship channel. This is upestuary from channel marker "16". Currents were often strong and the bottom was more irregular than at any of the previously described stations. Shell debris was common in sled tows. Salinities ranged from 6 to 34 ppt on the bottom, and there was usually little difference between surface and bottom. Mother Norton (MN) Shoal station was the most seaward of the 14 stations. The samples were taken on the southern side of the ship channel near the base of the south jetty on South Island. Tows 2-9 were parallel to the channel and seaward of marker "I1". The bottomI was entirely sand and subject to major changes between cruises as3 a result of strong tidal currents. Salinities at the bottom were always greater than 30 ppt and the lowest surface measurements were3 about 22 ppt. Surface-bottom differences were as great as 11 ppt. 2-10~~~~~~ CHAPTER 3. THE SAMPLING PROGRAM: METHODS AND MATERIALS The field sampling program designed for the second phase of the Winyah Bay Study consisted of five major series. These series will be described in detail in this section following a description of the methods used for sampling the physical, chemical, and biological components of the estuary. Most of the physical- chemical, zooplankton, and epibenthic sled sampling procedures were similar to those described in our previous report on the first phase of the Winyah Bay Study (Allen et al., 1982). A complete set of physical measurements was taken at each station on each cruise. Multiple sets were taken at each station on certain cruises so that changes in animal abundance could be related to changes in several characteristics of the water column. Water temperature, conductivity, and salinity were measured at increments of one meter from surface to bottom with a Bechman RS-5 induction salinometer. Water depth was determined from the weighted, calibrated probe cable on the salinometer. Vertical visibility was measured with a 25 cm diameter Secchi disk on daylight sampling cruises. Current direction and meterological conditions were recorded in conjunction with the temperature-salinity measurements. On the short-term sampling series, tidal current velocity was measured with a Teledyne Gurley vane type current meter. 3-1 During all cruises, water samples were collected for chemical nutrient and plant pigment analyses. A one liter water sample was collected from about 30 cm below the surface and 30 cm above the bottom with a Niskin-type cylindrical sampler which could be closed with a sliding messenger once the sampler was situated at the proper depth. Once the sample was collected, a 3 ml unfiltered volume was pipetted into a prewashed culture tube and a 15 ml sample was filtered (Gelman glass fiber filter, Type A/F, 25 mm), preserved with two drops of mercuric chloride, and stored in acid washed vials. After this field processing, the samples were frozen on dry ice and returned to the laboratory for analysis. In the laboratory, nutrient concentrations were determined on a Technicon Auto Analyzer II. Filtered samples were used for the analysis of orthophsophate and (nitrate and nitrite) nitrogen. The basic method for analysis of orthophosphate followed that of Murphy and Riley (1962) as modified in Technicon Industrial Method No. 155-71W (1973) and described by Glibert and Loder (1977). The basic method for analysis of (nitrate and nitrite) nitrogen followed that of Technicon Industrial Method No. 158 71W (1972) as described by Glibert and Loder (1977). Unfiltered samples were used for the determination of total nitrogen and total phosphorous. Analysis was performed on a Technicon Auto Analyzer II and followed the basic procedure suggested by D'Elia et al., (1977) as modified by Edwards (unpublished). Concentratioius of chlorophyll a and phaeo-pigments were also 3-2 determined from the bottom and surface water samples. From the one liter samples, 20 ml was pipetted to a filtration apparatus consisting of Gelman glass fiber filters (type, -A/E, 25 mm). The filters were placed in scintillation vials that were prewashed in 90% acetone. Saturated magnesium carbonate solution (1 ml) was added and the vials were frozen in the field. In the laboratory, 9 ml of 100% acetone were added to the frozen samples resulting in a 90% acetone extraction solution. The samples were periodically agitated and stored at 5�C for 24 hours. A Turner flourometer was used to determine chlorophyll a and phaeo-pigments according to the method of Yentsch and Menzel (1963). Further information on the procedure is found in Holm-Hansen et al. (1965) and Strickland and Parsons (1972). During the special chemistry transect and the 48 hour zooplankton series, water samples were analyzed for total and dissolved carbon, total dissolved phosphorus, total dissolved nitrogen, and ammonia (NH4) in addition to the other parameters previously discussed. Two 15 ml samples (one filtered) were stored in acid-washed scintillation vials and refrigerated until they could be analyzed for dissolved and total organic carbon. Two 3 ml filtered samples were pipetted into pre-washed culture tubes and frozen on dry ice (for total dissolved nitrogen and total dissolved phosphorus). One 15 ml filtered sample was preserved with one drop of phenol and refrigerated for future ammonia analysis. Analysis of total dissolved nitrogen and phosphorus was conducted 3-3 on a Technicon Auto Analyzer II and followed the alkaline persulfate procedure as outlined by Gilbert et al. (1977). Ammonia analysis was also conducted on the Auto Analyzer and followed the "Berthelot reaction" method (Fiore, and O-Brien, 1962). Carbon samples were analyzed with a Beckman carbon analyzer (Model 915A) according to procedures recommended by the American Public Health Association (1981). A variety of sampling gear and techniques were used to collect microscopic organisms in the water column. Three basic types of zooplankton nets were used. One set of nets consisted of 30 cm diameter ring nets. These nets were towed against the current for a total of 90 seconds. Boat speed was increased every 30 seconds so that samples could be collected for about 30 seconds at each of three levels (bottom, middle, and upper) of the water column. These collections, known as oblique tows, were used to obtain samples which represented the entire water column. Another type of apparatus used to collect zooplankton was a square mouthed opening-closing net. These nets were deployed from an anchored boat during periods when tidal currents were sufficiently strong to push water and animals into the nets. To obtain a bottom sample, the apparatus would be lowered to the bottom, lifted up about 20 cm, and opened by means of a sliding messenger. On nets rigged with a double trip device, a second sliding weight was used to close the mouth of the net before hauling back to the surface. A surface sample was taken with the net mouth centered about 50 3-4 cm below the surface. Collections were made with both 153 gm and 365 gm mesh Nytex nets. All nets were fitted with General Oceanics Model 2030 torpedo type flowmeters to measure the volume of water filtered during the collection. Tows were usually for 90 seconds, but on some occasions, nets were set up to four minutes so that enough water would be filtered to yield a meaningful sample. Two sets of nets were usually deployed at the same time and place in order to assess the degree of patchiness in the water column. When the collection was removed from the net, it was placed in a labelled jar and preserved in a 10% borax buffered formalin solution with rose bengal stain. In the laboratory, a 2 ml subsample was taken from each collection and examined under a microscope. Copepod crustaceans, which generally dominated the samples, were identified and counted to species. Other organisms were assigned -to one of more than 50 other taxonomic categories. It usually took a trained technician about two hours to process a single zooplankton sample on the microscope. A complete list of zooplankton categories which occur in Winyah Bay was presented in Allen et al., 1982. Small motile organisms including early developmental stages of fishes, crabs, and shrimps were collected with an epibenthic sled. This apparatus consisted of a steel frame which oriented a rectangular (51 X 30 cm) net mouth perpendicular to the bottom. A set of skis enabled the frame to be towed just high enough off the bottom so that the device did not dig into the substrate. Thus, small animals within 30 cm of the bottom would be swept into the 3-5 365 mm mesh net as the device was towed behind a boat. Occasionally, a second net which collected animals 30-60 cm above the bottom was mounted above the net which sampled on the 0-30 cm zone. The sleds were fitted with the flowmeters identical to those used in zooplankton nets. Tows were usually for six minutes in the direction that the tidal current was moving. Landmarks were used to identify the same tow path on each cruise. Two or three collections were made in each combination of time and space to provide replicate samples. Samples were removed and preserved on board. in the laboratory, entire samples were processed unless large volumes of detritus or organisms required that the sample be split. At least 12.5% of each sample was counted. Each collection required about two hours of processing time on the microscope. Details of the taxonomic categories for the zooplankton and motile epibenthos are given in other sections of this report. A. Extensive Series The first series of collections in this second phase of the Winyah Bay Study is referred to as the Extensive series. This series of seven cruises was an extension of the series of nine cruises completed between August 1980 and August 1981. The six stations (SR, PD, WR, MB, EP, and MN) sampled during the first phase were visited again during the second phase, and starting in September 1981 an additional six stations (PR, TA, BI, TC, PS, and SB) were sampled in the same manner. The dates on which the extensive stations were visited are listed in Table 3-1. 3-6 TABLE 3-1 Sampling dates for the Extensive and Intensive Series in Winyah Bay I ~~~~~~~Cruise dates: Extensive Series September 29 and 30, 1981 November 31 and December 2, 1981 January 25 and 26, 1982 March 25 and 26, 1982 May 25 and 26, 1982 July 27, 1982 I ~ ~~~~~~~September 22, 1982 Cruise dates: Intensive Series September 28, 1981 3 ~~~~~~~~~~November 30, 1981 January 27, 1982 March 24, 1982 May 24, 1982 July 26, 1982 I ~~~~~~~~~~September 21, 1982 3-7 On each of the extensive cruises, single observations were recorded for atmospheric conditions, current direction, secchi visibility and depth at each station. Then a water temperature and salinity profile was taken. Water samples were collected from surface and bottom and later analyzed in the laboratory for total nitrogen, nitrate/nitrite, total phosphorus, orthophosphate, chlorophyll a, and phaeopigments. Zooplankton collections were made with both 153 gm and 365 gm nets at each station. Two simultaneous 90 second oblique tows were made with each mesh size. Two sequential six minute epibenthic sled tows were made with another boat at the same time that the zooplankton tows were being collected. B. Intensive Series This series of seven cruises was conducted during the same week as the extensive series, but the sampling plan on this series examined differences in the chemistry and biology at the surface and bottom. On the intensive cruises, more measurements were made at each station so that only three stations (one each in the lower (MN), middle (MS), and upper (US) portions of the estuary) were visited on that day. The cruise dates are given in Table 3-1. At each station single observations were made for atmospheric conditions (air temperature, wind direction and speed, cloud cover), secchi visibility, depth, and current direction. Water temperature 3-8 and salinity were recorded at one meter increments. Water samples were collected at the surface and bottom and later analyzed for total nitrogen, nitrate/nitrite, total phosphorus, orthophosphate, chlorophyll a, and phaeopigments. A set of eight zooplankton collections was taken with opening- closing nets at each station. First, two simultaneous 153 gm mesh collections were taken at the bottom, then two simultaneous 153 gm mesh collections were taken at the surface. Two simultaneous 365 gm mesh collections were then made at the bottom and followed with a pair at the surface. All tows were made with moderate to strong ebbing tides and lasted about 90 seconds. A set of twelve epibenthic sled collections was taken from another boat at the same time the zooplankton samples were being collected. Two sequential three minute tows were followed by two simultaneous three minute tows. Thenthe same procedure was followed to obtain six minute and nine minute collections. All tows were in the direction of the ebbing tide and originated from the same starting point adjacent to the stationary zooplankton boat. The tows were approximately 300, 600, and 900 meters in length for the 3, 6, and 9 minute collections respectively. C. 48 Hour Zooplankton Series This special series was collected from September 18 (1000 hr) to September 20 (1200 hr), 1982 at the Mother Norton Shoal (MN) station near the mouth of Winyah Bay. Physical measurements and 3-9 water samples were collected every hour for the 48 hour study. Wind conditions, air temperature, secchi visibility, and depth were recorded. Surface and bottom temperature, conductivity, salinity, and current velocity were measured. Water samples taken from the surface and bottom every hour were later analyzed for total nitrogen, nitrate/ nitrite, ammonia, total dissolved nitrogen, total phosphorus, orthophosphate, total dissolved phosphorus, total organic carbon, total dissolved organic carbon, chlorophyll a, and phaeopigments. Zooplankton collections were made with 153 gm opening-closing nets. Simultaneous collections were made at the bottom, then the surface from an anchored boat every two hours. Tow duration was estimated from a pre-collection flowmeter test to assure that sufficient time was allowed to filter a minimum volume of water. Most collections were for three minutes. Laboratory analyses of the samples were similar to those used in the other series. Only dominant copepods were enumerated to the species level. Other copepods and meroplanktonic forms were counted at higher taxonomic levels. D. Special multi-level epibenthos series On September 17, 1982, organisms susceptible to capture in 365 3m mesh nets were sampled at the Mother Norton Shoal (MN) station. The complex sampling program was designed to allow comparisons: (1) between catches at the surface and bottom, (2) between ingle level sleds, double level sleds, and opening-closing 3-10 nets, (3) between slow, moderate, and high velocity tidal currents, and (4) between passive (from a stationary boat) tows, with-the- tide tows, and against-the-tide tows. During the 8 hr cruise, secchi visibility, water temperature, salinity, and current direction and velocity were measured at three levels. Measurements were made at 30 cm below the surface, middepth, and 90 cm above the bottom during each of the three stages of the tide. All net collections were six minutes long. At each of the three tidal stages the following sequence of collections was made; Stage 1 Boat 1: simultaneous double level sleds from an anchored position Boat 2: simultaneous closing nets at bottom from an anchored position Stage 2 Boat 1: simultaneous double level sleds towed against the tide Boat 2: simultaneous closing nets at surface from an anchored position Stage 3 Boat 1: simultaneous double level sleds towed with the tide Boat 2: single sled towed with the tide Stage 4 Boat 1: simultaneous single sleds towed with the tide Boat 2: single sled towed with the tide The first set of samples was taken around slack high tide in the morning. The four stages took approximately one hour to complete. 3-11 The second set started about an hour and one half after high tide and the last set started about two and one half hours into the ebb tide when tidal current velocities reached a maximum. E. Special Chemistry Transect Series These seven cruises were done during the same weeks as the extensive and intensive cruises. Sampling was initiated at Mother Norton Shoal (MN) near slack flood tide and samples were collected at stations along the ship channel in Winyah Bay. The first collection (at MN) was at the highest salinity station (usually about 34 ppt) and subsequent collections were made at locations where the salinity was 5 ppt less than at the previous station. Due to the highly variable nature-of the salinity regime in the estuary, the number of stations sampled on each cruise was not consistent. Table 3-2 summarizes the sampling program and shows that during periods of maximum freshwater inflow (e.g. January) all collections were made within Winyah Bay. During low flow conditions, a number of stations were sampled upstream of the Highway 17 bridges in the Pee Dee and Waccamaw Rivers. Meterological observations (air temperature, wind direction and velocity), secchi visibility, and depth were recorded at each station. Surface and bottom temperature, conductivity, and salinity were measured and a water sample was usually taken at each level. In the laboratory, water samples were analyzed for concentrations of total nitrogen, total dissolved ritrogen, nitrate/nitrite ammonia, total phosphorus, orthophosphate, total dissolved phosphorus, 3-12 Table 3-2 Sampling dates and distribution of collections taken during the Special Chemistry Transect Series in Winyah Bay. Total Samples Total Samples Total Samples Total Samples Date In Winyah Bay In Pee Dee R. In Waccamaw R. On Cruise Sep. 1, 1981 13 6 5 24 Dec. 10, 1981 12 5 5 22 Jan. 29, 1982 16 0 0 16 Mar. 27, 1982 16 1 1 18 May 28, 1982 12 5 5 22 Jul. 25, 1982 14 1 1 16 Sep. 23, 1982 10 4 8 22 Total in Series 93 22 25 140 I dissolved organic carbon, total organic carbon, chlorophyll a and I phaeophytin. I I i 1I I U I I I I I I I I 3-14 I I ~~~~~~CHAPTER 4. PHYSICAL-CHEMICAL CHARACTERISTICS Introduction The following discussion of the results of the physical, chemical, 5 ~~~and pigment sampling programs conducted within Winyah Bay is divided into three sections. The first section contains results and analyses I ~~~of parameters measured during the extensive and intensive series of 3 ~~~cruises and the special chemistry transect series. By presenting this information first, the reader is introduced to the patterns of spatial j ~~~variability within the bay. It should be reiterated that water samples for the extensive and intensive series of cruises were not necessarily collected on the same day nor during the same tidal stage. However, water samples for I ~~~the special chemistry transect series were collected on the same day and generally within three hours of slack high tide. Sampling commenced at Mother Norton shoals at slack high tide and ended at the river R ~~~stations approximately three hours later. Therefore, water samples were collected within a relatively short time span and during the 5 ~~~same tidal stage. One major advantage to the sampling program maintained during the special transect series is that nutrient and pigment concentrations are obtained along the entiire salinity gradient. It is therefore possible to pinpoint sources and sinks of nutrients within the estuary as a whole. Also, by first understanding seasonal nutrient regimes 3 ~~~~~~~~~~~~~4-1 for the entire estuary, it is possible to explain values obtained at individual stations during the ext ensive and intensive series of5 cruises. The second section presents results and discussion of the parameters examined during the 48 hour zooplankton series. It provides a more detailed look at the short-term temporal variability at a single station.J The final section summarizes information presented in the first two sections and provides a general description of the temporal and spatialI variability of nutrients and plant pigments within Winyah Bay estuary. Also, results from Winyah Bay are compared to conditions observed at No Man's Friend and South Jones Creeks.1 Section II in the first part of this section, general patterns identifiedI during the special chemistry transect series for the chemical and pigment constituents are presented. Following this introduction isI a more detailed discussion of concentration ranges, seasonal and5 spatial variability, and unusual trends exhibited at the stations sampled during the extensive and intensive series of cruises.5 Data for individual chemical and pigment parameters from the special chemistry transect series were plotted against salinity toa examine their behavior within the estuary. Four different mixing patterns were possible. A Ilinear relationship of nutrients or pig- ments and salinity suggests that a constituent is mixing conserva- 4-21 t ~~~tively within the estuary. A negative linear trend is exhibited when freshwater inputs served as a source for the nutrient. Conversely, a positive linear trend is indicative of an oceanic source. Throughout 3 ~~~the study, nutrient concentrations in freshwater were generally higher than those observed in high salinity samples. Unless otherwise noted, 3 ~~~reference to a conservative mixing trend should be construed to mean that riverine inputs were the source of the nutrient and concentrations 3 ~~~decreased in a linear fashion as salinity increased. Two other mixing patterns were possible. A negative convex upward I ~~~curve was obtained when the estuary served as a source for the nutrient. When the estuary acted as a sink, negative concave upward curves were obtained. 3 ~~~~Although patterns illustrated by the plots are affected by numerous factors and should therefore be interpreted cautiously, this approach does provide a qualitative basis for understanding transport dynamics within the system. Also, this approach has been used in several other S ~ ~~estuaries to examine mixing patterns of silicate, trace metals, dis- solved oxygen, alkalinity, carbon, chemical nutrients, chlorophyll, and productivity. A more detailed explanation of this approach can ft ~~be found in numerous publications (refer to Sharp et al., 1982, and references included therein). Physical parameters are discussed first, followed by descriptions of the nutrient and pigment concentrations within Winyah Bay during I ~~~the sampling period. A brief discussion (from Allen et al., 1982) of j ~~~the importance of the individual nutriernts and pigments to estuarine 1~~~~~~~~~~~~~- ecosystem dynamics is included. All data collected during the intensive and extensive series of cruises are tabulated by station in Appendix I. Physical/chemical and plant pigment data collected during the special chemistry transect series are tabulated by salinity in Appendix III. Water Temperature Surface and bottom water temperatures were highest from May through September 1982 (range; 22.8 - 30.8�T). at all stations sampled during the extensive and intensive series of cruises. Highest average water temperatures were recorded in July and ranged from 26.3 to 30.8�C. The annual trend consisted of decreasing temperatures from July through January and increasing temperatures thereafter. The January low tem- peratures ranged from 4.6 to 7.6�C. Station differences in water temperature were small from September through January and no consistent unusual trends were observed. During March and May, riverine waters were warmer than oceanic waters. For example, during March a surface water temperature of 17.6�C was recorded at US. Surface temperatures were progressively cooler approaching MN. Values of 16.3 and 14.7�C were recorded at MS and MN respectively. A similar but less extreme trend was found in May when surface tempera- tures of 24.2 and 26.0'0 were recorded at MN and US, respectively. Such behavior is to be expected during the spring months when increased solar radiation warms the more turbid riverine water faster than ,ceanic water. Depth is also an important factor since shallow bodies 4-4 5 ~~~of water (rivers, lakes, etc.) can be warmed much faster than deeper oceanic water. I ~ ~~~A reverse trend was observed in November and January when high 9 ~~~salinity stations were slightly warmer than the freshwater stations. This trend was somewhat obscured by the warming that took place 3 ~~~within Winyah Bay during this period. Increasing water temperatures within the bay were most noticeable during July when water temperatures were 1-2'C warmer within the Mud Bay area than at other sites. Shallow basins such as Mud Bay are particularly susceptible to extreme tempera- V ~ ~~ture variations. F'looding of -warm exposed marsh surfaces and mud flats during the suimmer may significantly elevate water temperatures. Condi- tions or high turbidity also affect water temperature. Silt-laden 3 ~~~water tends to warm much faster than clearer water. Significant thermocline formation (temperature stratification within the water column) was not observed at most stations during any portion of the year. Surface and bottom temperatures rarely differed I ~~~by more than I'C. However, exceptions to this were recorded during May and July at the deepest stations where surface water temperatures were up to 2-30C warmer than bottom temperatures. Thi;s feature is t ~~~probably a predominant feature at deep high salinity estuarine stations during late spring and early summer when freshwater inputs are generally warmer than oceanic water. When this is the case, warmer less saline water tends to flow over cooler high salinity water and a salt wedge I ~~~or halocline (salinity stratification within the water column) is formed. Haloclines were commonly observed in Winyah Bay channels, 'iut 1 ~~~~~~~~~~~~~4-5 such stratification was prevented by high wind and current velocitiesI in shallow portions of the estuary.5 Relatively large seasonal temperature fluctuations were observed at the stations. July temperatures averaged 20 - 25"C warmer than January temperatures. Temperature variations between stations within Winyah Bay were generally less than 30C during a particular cruise. Diel temperature fluctuations will be addressed in Section II. Salinity9 Observed salinity values were primarily dependent on the degree ' of dilution of sea water by the riverine freshwater inputs. Inflow is related to the amount of freshwater entering the estuary as well as tidal intrusion of sea water. The amount of sea water entering the estuary is related to lunar phase (i. e. spring and neap tides), wind, and meteorological conditions. Figure 4-1 illustrates the sur- f ace salinity regime at three sites from MN (highest average salinity station) to progressively less saline areas (MS and US) throughout the sampling period. It is readily apparent that spatial variablility in salinity is large within Winyah Bay. The maximum range of salinitiesk observed during a cruise was 33.3 g/l. Salinities were generally highest in November and lowest in January after a period of signifi- cant precipitation. Salinity stratification was observed at all deep water stations during most of the year. Salinity differences of 10 - 15 g/l between surface and bottom water samples were common. This feature serves 4-6 36 A-~~~ ~MN 32 28- 24 a-.~.. 20 - 0 20 - '~16- - \MS 1 2- �~~~~ V ~~4- U I~~~ - u 0- I I I I I * I SEP NOV JAN MAR MAY JUL SEP Fig 4-1. Surface salinity regime at three sites (MN, MS, and US) during the intensive series of cruises within Winyah Bay from September 1981-September 1982. 4-7 as a significant factor affecting the distribution of many organisms and the formation and maintenance of a permanent community structure. This relationship will be discussed in much greater detail in Chapters 5 and 6. Persistance of a halocline can significantly affect nutrient and phytoplankton concentrations. When a halocline is present, phyto- plankton can be effectively trapped within the lower more stagnant water body and this often results in decreased primary production. Also, decomposition within this water mass can result in depletion of oxygen reserves and, therefore, have potentially adverse conse- quences on animal community metabolism and structure. Many factors affect the formation and maintenance of a halocline. High wind and current velocities break down or prevent stratification. Shallow areas (i. e. Mud Bay) rarely experience significant stratifi- cation since moderate to low wind velocities provide sufficient mixing to prevent such an occurrence. The relationship of salinity to nutrients will be discussed indivi- dually under the appropriate category. Secchi Disk Visibility Vertical visibility was measured with a secchi disk. Secchi disk visibility is directly related to the vertical coefficient of light absorbtion which is the region from the surface to the depth at which 99% of the surface light has disappeared (Cole, 1975). This region 4-8 is referred to as the euphotic zone, and is ecologically important because little or no photosynthesis can occur below this zone. Average secchi disk visibility for all intensive and extensive stations increased from September 1981 (0.621 m) to a maximum value of 0.657 m in November 1981. The lowest average value was recorded in January 1982 (0.433 m) and was followed by a significant increase in March (0.592 m). Secchi disk visibility subsequently decreased from March to July (0.556 m) and increased slightly in September 1982 (0.598 m). The low visibility observed in January was a direct result of high levels of freshwater input to the system. Heavy freshwater input resulted in increased turbidity which was related to increased erosion and silt loading upestuary. Decreased visibility from March through July was influenced by increased densities of phytoplankton and detrital material in the water column as well as increased agri- cultural runoff associated with spring planting upstream. Highest average secchi disk visibilities were recorded at MN and SB (0.689 and 0.706 m, respectively). These two stations represented the two most saline areas sampled. Dilution of silt laden freshwater at these locations resulted in a concomitant increase in secchi disk visibility. Phytoplankton and detrital concentrations are also usually lower in oceanic water. Several other factors influence the visibility at the more seaward stations including color of the water and tidal mixing. Average annual secchi visibility was low at the river stations, rav,7ing from 0.540 to 0.597 m at PD, SR, WR, and US. Lowest average 4-9 visibilities were recorded at TA and PS (0.446 and 0.507 m, respectively). Both sites were located within the shallow Mud Bay area. Numerous factors are responsible for the low values. Wind velocity affects visibility within Mud Bay much more than at other sites. Low wind velocities can cause complete mixing of the water column at Mud Bay resulting in' resus- pension of silt, detritus, and phytoplankton. At the other deeper water sites, low wind velocities generally affect only the upper strata. Complete mixing of the water column is also indicated by the absence of salinity and temperature stratification within Mud Bay which contrasts with the extreme salinity stratification characteristic of deep water sites within Winyah Bay. Tidal mixing and phytoplankton production are also important factors contributing to the low secchi disk visibility within Mud Bay. Phosphorus Phosphorus is vital in the operation of cellular energy transfer systems. Phosphorus is typically scarce in unpolluted environments and is often a major limiting factor to aquatic productivity. Phosphorus, usually in the form of orthophosphate, is rapidly assimilated by phyto- plankton as soon as it-is made available And is then passed to higher trophic levels through herlivory and subsequent predation. Concentration of phosphorus in estuarine waters is primarily affected by basin mor- phometry, geochemistry of the watershed, input of organic matter, organic metabolism in the water column, and the rate of loss of 4-10 phosphorus to the sediments (Reid and Wood, 1976). Examination of composite plots of total phosphorus and total dissolved phosphorus in surface water samples versus salinity for the special chemistry transect series revealed a trend of conserva- tive mixing from September 1981 through March 1982 (fall through spring). From May through September 1982, Winyah Bay appeared to act as a sink for BIoth constituents, with the exception of May 1982 when total phosphorus followed a conservative mixing trend. Although values were low and extremely variable throughout the year, Winyah Bay generally acted as a sink for orthophosphate. These results reflect the influence of phytoplankton on the nutrient regime within the bay. During cooler months when primary production is relatively low, total and total dissolved phosphorus mixing is conservative. As primary production increases within the bay, phosphorus tends to remain within the system. Mixing patterns and low concentrations of orthophosphate are the result of rapid assimilation of these nutrients by phytoplankton throughout the year. During the extensive and intensive series of cruises, highest average concentrations of total phosphorus (3.1 a At./1) and ortho- phosphate (1.1 m At./1) were observed in January and March, respec- tively. These findings reflect the significant input of nutrient- rich freshwater to the system during January. High values of ortho- phosphate during March suggest that it was made available to the environment faster than it could be assimilated by the phytoplankton. Second highest average concentrations of total phosphorus (2.6 u At-./1) 4-11 during July in Winyah Bay were caused by both high concentrations in the freshwater inputs and high primary productivity within the system. Lowest average total phosphorus concentrations (1.5 g At./I) were re- corded in November 1981 when freshwater inputs to the system were low and primary production was minimal. Average concentrations of total phosphorus in surface samples were generally higher at sites within Mud Bay than in other deeper water sites. For example, average surface concentration of total phosphorus at TA was 3.0 u At./1 compared to 1.8 g At./1 at MS. Ion exchanges between sediments and overlying water, and activity by microorganisms are probably responsible for this. phenomenon (Gooch, 1968; Pomeroy et al., 1969). Circulation of phosphorus retained in the sediments by nearby extensive stands of Spartina alterniflora may also be important (Pomeroy et al., 1969). Nitrogen Nitrogen is used in the synthesis of protein which is a major consti- tuent of living cells and, therefore, is essential to the existence of an ecosystem. Atmospheric nitrogen acts as a reservoir for a complex cycle involving plants, animals, and various forms of the element. Nitrogenous compounds are made available to the estuarine environment by bacterial fixation of elemental nitrogen, precipitation, surface runoff, riverine inputs, photochemical and lightning fixation, decomposing plant and animal tissues, and animal excretory products (amino acids, urea, uric 4-12 acid, ammonia). Available nitrogen is transformed into nitrates through bacterial action. Ammonium-nitrogen and, to a lesser extent, nitrite-nitrogen can be utilized by some phytoplankton species, although nitrate-nitrogen is primarily taken up by the cells and transformed into complex proteins (Russell-Hunter, 1970). Concentrations of inorganic nitrogen compounds (ammonia, nitrite, nitrate) regulate the productivity of an aquatic ecosystem because they are used in the synthesis of plant proteins which form the basis of the aquatic food web. Total nitrogen, total dissolved nitrogen, and nitrate-nitrite nitrogen generally followed a pattern of conservative mixing throughout the year. A composite plot of these three constituents plus ammonia from the July 1982 special chemistry transect cruise is presented in Figure 4-2. The apparent conservative mixing trends of total nitrogen, total dissolved nitrogen, and nitrate-nitrite nitrogen are representative of most other cruises. Total dissolved nitrogen constituted a significant portion of total nitrogen throughout the year. Although ammonia appears to be mixing conservatively during this particular cruise, this trend was not consistent. During September 1981, ammonia showed a distinct estuarine source. Ammonia concentrations were approximately I u At./1 at the freshwater and high salinity ends, but values averaging 5-6 g At./1 were recorded at mesohaline sites (10-26 g/l). During other cruises, ammonia values were usually low and highly variable, and no consistent trends were established. Conservative nitrogen behavior has been observed in nonurban tropical estuaries (Van Bennekom et al., 1978; Fanning and Maynard, 1978) and the Columbia Riier estuary (Stefansson -nd Richards, 1963). 4-13 Fig 4-2. Composite plot of total nitrogen and dissolved nitrogen fractions versus salinity for surface water samples collected during the July 1982 special chemistry transect cruise. 70 60 50 ' Total Nitrogen 40- 30 - Total Dissolved Nitrogen 20- Nitrate-Nitrite 10 - Ammonia I I I I I I I i I I I I I I I I I I I 0 4 8 12 16 20 24 28 32 36 salinity (�/oo) * _ _ - Z mW _r _ _ _ m During the extensive and intensive series :of cruises, maximum average concentrations of nitrate-nitrite nitrogen were recorded in January and March (17.4 and 25.0 g At./1, respectively). This period corresponded to the period of maximum freshwater input to the estuary. High levels of nitrogen loading from freshwater sources as a result of surface runoff within the watershed, and heavy detrital loading followed by decomposition were important factors during this period. Maximum values reaching 33.38 g At./I were usually recorded at upper estuary sites (WR and US). Lowest average nitrate-nitrite nitrogen concentration (2.61 u At./1) was obtained in September 1982 and corresponded to maximum densities of phytoplankton. Nitrate-nitrite nitrogen is rapidly assimilated by phytoplankton and a significant inverse relationship of phytoplankton to nitrate has been demonstrated (Tiner, 1981). Lowest nitrate-nitrite nitrogen concentrations were usually observed at the most seaward sites (MN and SB). Average cruise concentrations of total nitrogen did not follow established trends which were observed in the previous study of No Man's Friend and South Jones Creeks where total nitrogen tracked phytoplankton abundance (Allen et al., 1982). Lowest average total nitrogen concentrations were recorded in September 1982 when chlor- ophyll a values werehigh. Highest average concentrations were recorded in November and January (81.0 and 74.9 g At./1, respectively) when chlorophyll a values were low. Several factors were probably responsible for this anomalous behavior. The highest total nitrogen concentrations, 4-15 ranging from 108-168 a At./1, were recorded at mid-estuary stations (EP, US, BI). Dredging, which was observed adjacent to these sites, may have affected total nitrogen concentrations. Heavy freshwater inputs of nitrate-nitrite nitrogen and other forms of nitrogen were partially responsible for the high total nitrogen values observed during January. Highest average total nitrogen concentrations for all cruises were observed at EP, BI, SR, and US. Lowest average values were most com- monly recorded at MN. Chlorophyll a, Phaeo-pigments, and Organic Carbon Due to their capacity to photosynthesize, plants occupy the base of most food chains. There are two basic food chains in estuarine environ- ments. In one, rooted angiosperms and epiphytes are the primary producers, and in the other, phytoplankton are the primary producers (Russell-Hunter, 1970). In either case, the generated plant tissues are fed upon directly by grazing (herbivory), or indirectly through the consumption of dead plant materials and decomposers (detritivory). There may be several steps involved in a single food chain. For example, a single food chain may include a diatom species (phytoplankton), a herbivorous zooplankton species, two predaceous zooplankton species, a small fish, and a larger fish. The production of fish and invertebrate tissue in an estuary or salt marsh is obviously directly related to the productivity of the green plants. Consequently, in order to understand fluctuations in the populations of zooplankton, epibenthic and benwhic organisms, and fish, 4-16 it is also necessary to understand primary productivity within the ecosystem. Phytoplankton represent a high proportion of the standing crop of primary producers in estuaries and salt marsh creeks. Phytoplankton are microscopic aquatic plants which are primarily transported by tidal and wind driven currents. Assessments of chlorophyll a concentrations were used as indicators of primary productivity in this study. Determination of chlorophyll a is a rapid chemical method for quantifying the amount of living plant matter in the water column, but the relationship between living organic plant material and the quantity of plant pigment is highly variable, depending upon the species composition of the phytoplankton in the water as well as their state of nutrition (Strickland and Parsons, 1972). Despite this limitation, assessment of chlorophyll a still serves as a useful tool, providing a relative index of seasonal and diurnal changes in the standing crop of phytoplankton. Degradation products of chlorophyll may constitute a significant portion of the total green pigments in the water column. Typically, phaeophytin and phaeophorbide (collectively termed phaeo-pigments) represent the greatest percentage of chlorophyll degradation products (Strickland and Parsons, 1972). Determination of phaeo-pigments serves as a useful t-ool in determining relative rates of phytoplankton turnover. Although chlorophyll a data collected during the special chemistry transect series was often highly variable, three distinct concentration patterns emerged (Figure 4-3). During September and November 1981, 4-17 12- /m 10- 8 - 0^ -X/ 6 00~~~ 4O 8-1 0242 23 0 0 4- o~~ I �~~ 2' 00 ?~~~~~~~~~~~~~~~~~~~~~~ 0 - ! I I ! I I I I I I I J I I I ! I I I 0 4 8 12 16 20 24 28 32 36 salinity (�/oo) Fig 4-3. Concentrations of chlorophyll a versus salinity from surface and bottom water samples collected during special chemistry transect cruises. Best linear regression lines represent datalrecorded for cruises I (September, 1981) and III (January 1982). Actual values recorded during cruise V (May 1982) are included add the concentration curve drawn was visually determined. One anomalous chlorophyll a value (>29) was not included. i' _ _' _ _ _ i' _ * I - M chlorophyll a concentrations appeared to decrease from freshwater to high salinity stations. Conversely, chlorophyll a concentrations increased from freshwater to high salinity areas during January 1982. From March through September 1982, the estuary was an apparent source of chlorophyll a; lowest values were observed at freshwater and high salinity areas. The usual pattern observed in January is likely related to the high degree of freshwater dilution throughout the estuary. Riverine and estuarine populations of phytoplankton were displaced toward the lower end of the bay. The strong correlation of phaeo-pigment and chlorophyll a concentra- tions which is typically observed in estuarine systems (Allen et al., 1982), was not consistently observed in Winyah Bay. This was due to the highly variable nature of the phaeo-pigment data. During most special chemistry transect cruises, the data were so variable that few clear and consistent trends could be established. In March 1982, phaeo-pigment and chlorophyll a concentrations appeared to track each other (Figure 4-4). On this particular cruise and two others (September and November 1981), phaeo- pigments appeared to have an estuarine source. Conservative mixing patterns were observed for total organic carbon and dissolved organic carbon throughout the year. During the extensive and intensive series of cruises, average chlorophyll a concentrations decreased from a high value of 6.13 mg/3. in September 1982. A spring peak may have occurred in Winyah Bay between the March and May cruises. 4-19 10' .8- CD~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 6 0 ~ 6l 9~~~~~~~~~~~~~~~ I 0 21 0 24 28323 '.C l am o Om 04 - .1I I I- ~~~~~~~~~~~~~~~~~~~~I I IJI-a I 1 0 4- p1 2 162- 4 2 23 ~~~~~~~~~slnty) (�/oo- Fg44Copstpotfhoohlaanphe-imncocnrtosvrusalntfo sufc a n 'otmwtrsmpe olce-uinspcachmtrtasetrue ~~V(a 92.Oeaom lu samlwanoicud. Maximum chlorophyll a concentrations for individual sampling periods were observed at several locations (TA, BI, EP, US, and SR) and probably represented patches of phytoplankton. Minimum average concentrations for individual cruises were most commonly recorded at WR (3 of 7 cruises) although minimal values were also observed at PD, PR, US, and SB. Average concentrations of phaeo-pigments for cruises generally tracked chlorophyll a concentrations. Phaeo-pigment concentrations decreased from an average value of 3.44 mg/m3 in September 1981 at all stations to a minimum of 1.53 mg/m. in November 1981 and then increased to a 3 maximum value of 5.04 mg/m3 in September 1982. Since phaeo-pigments are a degradation product of chlorophyll and values are related to zooplankton grazing and natural attrition of phytoplankton, a close seasonal correlation of chlorophyll a dnd phaeo-pigments may be expected. Section II Spatial and seasonal variability of physical, chemical, and pigment parameters were presented in the previous section. During the 48 hour zooplankton study, hourly changes in the parameters were recorded over a two day period. Although caution should be exercised in interpreting temporal variation over a single two day period, by combining these data with observations recorded during the 24 hour cruises at adjacent No Man's 4-21. Friend and South Jones Creeks (Allen et al , 1982), it is possible to examine the relative importance of diel, diurnal, and seasonal variation in Physical characteristics, and chemical and pigment concentrations. The first day of sampling was characterized by relatively clear skies and low to moderate wind velocities. Percentage of cloud cover and wind velocity increased during the second day and a severe storm interrupted sampling for a two and one-half hour period. Cloud cover remained, but wind velocities decreased through the remainder of the cruise. Specific data collected during the study are included in Appendix II. A description of physical, chemical, and pigment changes over the 48 hour period follows: Temperature Surface and bottom water temperatures only fluctuated from 25.8 to 27.4�C during the 48 hour study. During the first day, water temperature increased from a low of 25.8�C at 1000 hr to high values in late afternoon ranging from 27.1-27.4�C, and decreased thereafter to 26.60C at 2300 hr. Patterns exhibited during the second day were opposite to those observed on the first day. Temperatures decreased from a high of 26.9�C in early morning (0600 hr) to a daily low of 25.9�C at 1200 hr. This decline was evidently ca,-sed by the movement of a frontal system across Winyah Bay. 4-22 Sampling was missed during the severe storm which occurred from 1300-1500 hr. Water temperatures subsequently increased to approximately 26.50C after passage of the frontal system and remained relatively stable through the remainder of the sampling period (26.5 +/- 0.2�C). These minor fluctuations were probably not significant in terms of influences on chemical or biological processes measured during this period. Salinity Salinity of surface and bottom water ranged from 21.0 to 34.9 g/l through the 48 hour period (Figure 4-5). Salinity generally increased during the flooding tide and decreased during the ebbing tide. Salinity differences between surface and bottom samples were never greater than 3 gjl. The highest degree of salinity stratification occurred at times of low current velocity and was generally within one hour of slack tide. As current velocities increased, surface and bottom water mixed and this resulted in the breakdown of any halocline which had formed. A two-layered circulation pattern was observed around slack high tide when oceanic waters began to ebb. This pattern resulted in increasing bottom salinities and decreasing surface salinities. Salinity reductions of 3-4 g/1 occurred during the 3 hour period preceeding and following the passage of the frontal system through Winyah Bay (1300- 1500 hr, September 19, 1982). Thereafter, salinities resumed previous levels. 4-23 35' A~~~~~~ q 33- - 311 * 'I~~~ N v it h~~~~~~~~~~~~ 29 - 2 7 2 Io ~~I , ~~~~~~~~~~~~~~~ , I~~~: I\ a Fig 4-5. S~ a l nt o sufc(sldanbotm(oe)wtrdrig th 48huapin at o 29- : a " o . m m S 2- �, I/I I U) ' 23~~~~~~~~~~~~~~~~~~~~~~' 21- 1200 1800 0000 0600 1200 1800 0000 0600 1200 Fig: 4-5. Salinity of surface (solid) and bottom (dotted) water during the 48 hour sampling at Mother Norton Shoal (September 18-20, 1982). a Il �eE 1~~ 1Lr ' Lr I Phosphorus Total phosphorus concentrations ranged from 0.2 - 4.2 gg At/1 during the 48 hour study. Two dominant factors appeared to influence total phosphorus concentrations. Total phosphorus consistently increased during the ebbing tide to a maximum at slack low. This resulted from the input of phosphorus to the system from freshwater sources. Also, total phosphorus concentrations increased in bottom samples at slack low tide when salinity stratification was present. Ion exchanges between the pool of phosphorus in the sediments and overlying water was probably responsible for this phenomenon. Orthophosphate concentrations ranged from less than 0.1 pg At./I to 2.5 gg At./I. Sediment resuspension appeared to be the dominant factor controlling orthophosphate concentrations in the water column. Maximum values for orthophosphate were observed at maximum current velocities (mid flood and mid ebb; refer to Figure 4-6). During these periods, sediment loading in the water column was at a maximum and secchi disk visibility was correspondingly low. It should be noted, however, that immediately following the thunderstorm (after 1500 hr on September 19, 1982), high concentration values of orthophosphate were recorded at low tide (1700-1800 hr). These findings are not totally inconsistent, and are probably the result of high wind velocities causing bottom sediment resuspension and surface runoff of sediment and nutrients from the surrounding watershed. No consistent patterns were observed for total dissolved phosphorus. 4-25 2.6- 9 ma II em 2.2 ' co~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~a ISI a, i~~~~~~~~~~~~~~~~~~~~~' u~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ a 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /a i f�~~~~~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~ e I I 1.4 l.8 $4J t.O iIq i~' I !a - 0 a- : ,, 0.~~~~~~~~~6 0. 2 - 1200 1800 0000 0 601200 i,800 0000 0600 1200 Fig 4-6. Orthophosphate concentrations in surface (solid) and bottom (dotted) water during the 48 hour sampling at Mother Norton Shoal (September 18-~20, 1982). a-aI - (mam I Sa I * I S r~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I m 1.0-~~~ I, 0.- a a a a $1 m l ii : m a I5a I a~ a b d r 0.2- 0.a' U S I ' I ' * C S S I C I I * I IS 1200 1800 0000 060 1200 1800 0000 0600 1200 Fig 4-6. Orthophosphate concentrations in surface (solid) and bottom (dotted) water during the 48 hour sampling at Mother Norton Shoal (September 18-i20, 1982). Peaks at mid flood and mid ebb probably resulted from the significant contribution of orthophosphate to total dissolved phosphorus concentra- tions. High values at other times were likely related to increased biological activity which resulted in increases of dissolved organic phosphorus in the water column. Concentrations of total dissolved phosphorus ranged from less than 0.2 to 3.6 ug At./I. Nitrogen Total nitrogen concentrations ranged from approximately 8-68 Wg At./I during the 48 hour period. Although numerous factors affect total nitrogen levels, a conservative mixing trend was discernible. Consequently, highest total nitrogen concentrations were recorded at low tide when salinities were lowest. Total nitrogen concentrations decreased as high salinity water entered the bay. A similar conservative mixing pattern was observed for nitrate-nitrite nitrogen (Figure 4-7). Nitrate-nitrite nitrogen values generally ranged from 0.3-3.0 gg At./l. The highest value (3.66 ug At./I) was recorded after the storm on the second day and was probably influenced siginficantly by precipitation and surface runoff. Ammonia concentrations were typically in the range of 1-5 gg At/i. Although increases in ammonia concentration were observed at times when salinity stratification was present (most notably, slack high tide), a conservative mixing pattern was generally exhibited. However, the 4-27 4.0- 4' 3.5- 3.0' 2aa~~~~~~~~~~~~~~~~~~~~~~~~~~ l 2 0' O �� 0I I l!I '!~~~~~~C u~~~~~~~~~~~~~* ii I aI a va AK N a a a I , ,5 S I , ,,i, I It! I~~~~~~~~~~~~~~ 1.0- > I a.5- d a d aJ a 4- *11 S I I I I I I I I 1 I water , I a 0.s- I ' ! !, w aW j a I � a a I 00 1800 0000 0600 1200 1800 0000 0600 1200 Fig 4-7. Nitrate-nitrite nitrogen concentrations in surface (solid) and bottom (dotted) water during the 48 hour sampling at Mother Norton Shoal (September 18-20, 1982). data were highly variable and several other factors probably influenced ammonia availability in the water column. The approximate concentration range for total dissolved nitrogen was 8-51 ~g At./I. Dissolved fractions usually comprised nitrogen, and dissolved organic nitrogen fractions are constituents of total dissolved nitrogen. High values of ammonia and nitrate-nitrite nitrogen were usually reflected in total dissolved nitrogen concentrations. Other peaks in total dissolved nitrogen were presumably caused by dissolved organic fractions which often constitute a significant proportion of total dissolved nitrogen. Bacterial activity (decomposition) and animal excretion are two important biological sources of dissolved organic nitrogen. Chlorophyll a, Phaeo-pigments, and Carbon Maximum chlorophyll a concentrations (14.6 mg/mi3) were recorded near low tide during daylight hours on the first day (Figure 4-8). Subsequent daily low tide peaks were not as pronounced as those observed during the first day. Low values generally occurred at high tide and during night-time samples. Chlorophyll a concentrations as low as 1.9 mg/m. were recorded at high tide during the night. Temporally related variables, including tidal flushing and diurnal changes in photosynthetic rates, are often the most important determinants of phytoplankton abundance and primary production (Moll and Rohlf, 1981). 4-29 14- . II ;I gi II 12- I I I I 10- A Fig 4-8. Chlorophyll a concentrations in surface (solid) and bottom (dotted) water during the 48 hour sampling at Mother Norton Shoal (September 18-20, 1982). am i man o - ' 9 Phaeo-pigments closely tracked the pattern exhibited for chlorophyll a, which was probably related to the turnover of phytoplankton by zooplankton grazing and natural attrition. Since dead cells tend to settle to the bottom, surface phaeo-pigment concentrations were usually lower than bottom samples. Phaeo-pigment concentrations ranged from 0.5-12.8 mg/m3. Both dissolved and total organic carbon consistently exhibited highest values at low tide and lowest values at high tide throughout the 48 hour period. Total organic carbon values ranged from 2.6-6.4 mg/m3 and dissolved organic carbon values were similar. Freshwater inputs and concentrations within the water column were responsible for the high values observed at low tide. Section III The annual temperature range for Winyah Bay was 4.6-30.8�C. The annual water temperature pattern was similar to that observed in No Man's Friend and South Jones Creeks. Diel and diurnal temperature changes were usually an order of magnitude less than those recorded on an annual basis. Within Winyah Bay, temperature extremes were most often recorded in Mud Bay and were related to the shallow depth of the basin. Vertical temperature stratification in the bay was not significant. Thermocline formation is probably less important ecologically to community structure and nutrient availability in the bay than the significant 4-31 salinity stratification which was observed. The salintiy regime within Winyah Bay is a highly significant factor affecting nutrient availability, phytoplankton density, and invertebrate and vertebrate community structure. Salinity stratification, especially at the deeper water stations, is generally present throughout the year. At individual stations, salinity changes over the tidal cycle were frequently large. Changes in salinity of 20-25 g/l over the tidal cycle were common in the middle bay. The salinity regime at the river sites is more stable than at stations in the middle bay. Secchi disk visibility was usually most affected by biological activity. Generally,. visibility decreased as primary productivity increased. However, physical factors dominated in January when extremely high levels of freshwater input caused erosion and sediment loading in the watershed. This resulted in the lowest secchi disk visibilities recorded during the study. With the exception of January, annual trends in vertical visibility were similar to those recorded in NMF and SJ Creeks. Total phosphorus appears to mix conservatively within Winyah Bay during the cooler months when primary production is low. As primary productivity increases, Winyah Bay acts as a sink for total phosphorus. Orthophosphate is generally present in low concentrations throughout the year. Concentration of phosphorus in the system is significantly influenced by the amount of phosphorus entering the bay from riverine sources. The unusually high values observed in January were directly related to the high levels of freshwater input. Because of the January peaks in Winyah Bay, seasonal concentration plots were different from 4-32 those recorded for NMF and SJ Creeks. It is likely, though, that seasonal trends in Winyah Bay closely resemble those observed for NMF and SJ Creeks when freshwater input is low to moderate. When this is the case, total phosphorus concentration is heavily influenced by phytoplankton in the water column. Large changes in phosphorus concentrations can occur in a relatively short time period, and this was observed during the 48 hour study at Mother Norton Shoals. During this period, the range in total phosphorus concentration was greater than the average seasonal change for all stations. Mud Bay appears to be a major processing area for phosphorus within Winyah Bay. Low current velocities, shallow depths, and a large surface area contribute to this behavior. Nitrogen appears to mix conservatively in Winyah Bay throughout most of the year. Peak concentrations of total nitrogen in NMF and SJ Creeks appeared to coincide with phytoplankton densities. In Winyah Bay, however, nitrogen concentration was more closely related to the amount of nitrogen entering the bay from riverine sources. Short-term temporal variability in nitrogen concentrations; as observed at Mother Norton Shoals during the 48 hour sampling period, was as large as seasonal variability. Seasonal trends in chlorophyll a and phaeopigment concentrations were similar to those observed in NMF and SJ Creeks. Typically, chlorophyll a concentration and primary productivity is low in winter and high in summer. The absence of a spring peak in NMF and SJ Creeks and Winyah Bay 4-33 I was probably related to sampling frequency. In both studies, hourly changes in chlorophyll a concentration were often as large as seasonal 3 changes. 3 I a I I I I 11 a a II I I I 4-34 I I CHAPTER 5. ZOOPLANKTON The zooplankton community is comprised of a diverse assemblage of microscopic animals which are generally passively transported by water currents. The composition of the Winyah Bay zooplankton was discussed in considerable detail in the previous report (Allen et al., 1982). Information on the life histories, ecological roles, and spatial and temporal patterns of distribution was presented. This chapter sum- marizes the results of studies during Phase II and III of the project. The Winyah Bay ecosystem contains a great diversity of both per- manent and temporary planktonic forms. Among those species which spend their entire lives as plankton (holoplankton), copepods were generally the most abundant. The calanoid copepods, Acartia tonsa, Parvocalanus crassisrostris, Eurytemora affinis and Pseudodiaptomus coronatus are characteristic of eastern and southeastern coastal en- vironments and were common in Winyah Bay (Bowman, 1971; Alden, 1977; Lonsdale and Coull, 1977; Sandifer et al., 1980). Other calanoid copepods occasionally found in the area were Centropages hamatus, Centropages typicus, Centropages furcatus, Labidocera aestiva, Temora turbinata and Eucalanus spp. Among the cyclopoid copepods collected in Winyah Bay, only Oithona colcarva and Halicyclops spp. were common. Other cyclopoid species belonging to the genera Corycaeus, Cyclops, Eucyclops, Macrocyclops, Mesocyclops, Oncaea, Orthocyclops, Saphirella, 5-1 and Tropocyclops occurred only sporadically. Euterpina acutifrons, a cosmopolitan form, was the only harpacticoid copepod which regularly occurred in the bay. Other holoplanktonic crustaceans found in the study area included ostracods and cladocerans; however, these were not nearly as abundant as copepods. Other crustacean groups such as small decapod shrimps, isopods, amphipods, mysids, cumaceans, and stomatopods were uncommon in the zooplankton collections. Among the non-crustacean holoplankton, medusae, rotifers, appen- dicularians and chaetognaths commonly occurred in the samples. At times, these comprised a large percentage of the total organisms in the collections (Tables 5-1 and 5-2). The temporary or meroplanktonic forms consisted largely of the eggs and larval stages of fish and benthic invertebrates. The most common larvae found in the zooplankton collections were barnacles (nauplii and cyprids), crabs (zoeae), polychaetes, and molluscs (primarily gastropod veligers and bivalve larvae). During periods of peak abundance, these larvae accounted for a large percentage of total organisms in a sample. However, due to the diversity of these groups in the area, it is unlikely that multiple peaks of abundance represented larvae of the same species. Larvae of other benthic organisms were occasionally found at low densities. Pilidium larvae of nemerteans, Muller's larvae of turbellarians, actinotroch larvae of phoronids, cyphonautes larvae of bryozoans, and bipinnaria or pluteus larvae of echinoderms, were 5-2 Table 5-1. Relative abundance of the three most dominant categories expressed as percentage (in parentheses) of total zooplankton at each station on each extensive cruise. Italicized numbers are total categories present in each sample. ALL - annual means for each station; TOTAL means for each cruise for all stations. STATION SEP NOV JAN MAR MAY JUL SEP ALL F 3 11 is 10 17 12 12 13 PR AT (32) O N (62) RF (53) EA (77) AT (65) EA (59) O N (46) AT (30) ON 7) PL (14) CY (16) HA ( 6) CZ ( 9) CZ (21) AT (28) EA (28) CN ( 3) AT ( 8) EA ( 8) MC ( 6) cv ( 8) MC (15) ME (II) BN (10) r 2 9 19 9 10 12 9 11 SR iAT (84) AT (48) AF (36) EA (91) AT (72) cZ (43) RNI (83) AT (40) BN (10) PL (19) CY (24) CL ( 3) CZ (20) NC (19) BC C 7) RN (32) CM ( 2) RN (13) HA (11) CO N 2) RN ( 4) AT (I8) AT ( 6) EA (10) :2 MA 20 14 13 ME 13 14 P AT (85) AT (63) CL (33) EA (72) AT (83) MC (35) AT (63) AT (72) PC ON (10) FE (19) CY (32) CV C 8) BC ( 6) CZ (15) RN (27) RN ( 8) Pl (85) PL (12) HA ( 7) CY (72) PL (83) CM (35) ME (63) SC ( 4) 11 23 14 20 20 13 8 13 AT (90) FE (71) Os (44) EA (37) EA (46) EA (67) ME (38) AT (43) Wi t RN ( 5) AT (14) CY (17) CL (28) AT (45) NC (25) AT (38) EA (38) PL 2) CCM( 5) TP ( 9) CY (10) MC ( 6) CZ ( 3) ON (23) MC ( 6) F 10 24 22 15 15 19 13 15 AT (85) AT (76) CL (30) EA (72) AT (69) AT (72) ON (48) AT (68) el N (11) SM ( 8) CY (14) CM (14) CZ (1,c) MC (11) AT (43) SN (13) CM ( 1) PL ( 4) EA (11) CL ( 8) BC ( 7) CM ( 5) ME ( 4) CZ ( 5) is 16 20 14 11 12 9 14 TA AT (92) AT (34) E A (37) EA (67) AT (94) AT (47) AT (97) AT (90) T N ( 3) CH ( 7) CL (15) CM (15) RC ( 2) PL (25) ON ( 2) P. 2) L PC ( 1) PL (2) CY (11) CP ( 9) PL C I) EA (17) ME (.2) BC C 2) 13 14 21 16 10 14 6 13 PS nAT (79) AT (81) EA (35) EA (38) AT (93) AT (94) AT (97) AT (90) IPC(7) PC(9) OS (29) CM (36) PC(4) III.2) SN (2) PCC4) RN 6) ON ( 4) CL ( 7) OC ( 9) RN 1) CZ I) PC (.5) RN C 2) T 2 16 24 17 23 20 16 78 TC AT (69) AT (43) HA (20) OC (37) AT (73) AT (44) AT (67) AT (62)- ON (18) RN (42) OS (10) EA (15) BC ( 8) CZ (22) RN (21) ON (13) Pc ( 2) PC ( 4) EA ( 9) PC (11) PC ( 7) GV (15) cv ( 3) CZ ( 6) 14 21 28 15 27 17 12 i 8 AT (79) ON (69) CH (31) OS (31) AT (64) CM (29) ON (50) AT (53) ON (12) PC (8) AT (23) E A (20) PC (12) MC (24) AT (42) RN (20) PE ( 3) AT (5) CN (13) CY (14) ON (10) AT (23) BC ( 6) PC ( 2) 25 25 29 30 20 19 1 6 :2 AT (75) PC (24) EA (23) OC (27) AT (42) AT (54) AT (75) AT (55) Ms RN C 7) RN (21) BC (14) OS (18) RN (20) O N (11) RN ( 7) RN (13) PC ( 7) OC (11) CL ( 8) CM (11) PC (II) GV ( 9) CV ( 4) PC ( 8) 27 25 31 24 24 25 28 26 PC (33) ON (24) CP (28) OC (41) PC (42) AT (33) AT (31) PC (29) ON (21) PC (24) CM (12) CH (29) O N (23) ON (23) PC (22) eN (20) AT (12) CP (16) oC ( 8) Pc ( 8) EU ( 8) cv (10) BPI ( 8) AT (14) is 16 :2 17 15 1 6 13 - AT (77) AT (44) RF (18) EA (61) AT (65) AT (39) AT (53) AT (s8) TbTAL E R (13) RN (22) CY (12) OC (9) PC (7) EA (14) RN (32) RN (13) pC ( ) PC ( 9) EA (10) C( 5) EA (6) CZ (12) ME ( 3) EA ( 5) Organism abbreviations: AT- Acartia tonaa adults & copepodids GV - gastropod veligers 3C - barnacle cyprids HA - unidentified harpacticoid copepods RN : barnacle nauplii MC- - alicucloe SpQ. CM * Centmrc!aaea i.atu$8 ME M medusae CL - cladccerans (IC - oit;-ona cotcarva CM- copepod nauplii OS- ostracods CP - all ether copepodids PC - Pazvoc-alaua crassiroetris CV - unidentified cyclopoid copepods PE F Pseudodiaptoms s cOro~tue CZ - crap zoeae PL polychaete larvae EA - E:uxtl-cra affinia RF - rotifers EU- Euterpina acutifrcna TP - Tropcclgoopa pmainus FE - fish eggs & larvae 5-3 Table S-2. Relative abundance of the three most dominant categories expressed as percentage (in parentheses) of total zooplankton at each station on each intensive cruise. Italicized numbers are total categories present in each sample. S = surface tow; B - bottom tow: ALL = annual means For each station. STATION US MS LS TOw s B S B S B CRUISE 15 11 21 22 29 24 AT (86) AT (59) AT (74) AT (52) PC (27) PC (32) BN (6) GV (27) BN (7) PC (14) AT (14) AT (23) CN ( 3) BN ( 5) PC ( 7) PL ( 7) PL (12) PL (16) l1 14 22 23 26 . 25 AT (80) AT (87) AT (52) AT (60) PC (33) PC (34) CN ( 8) CN ( 6) BN (17) PC (11) OC (20) OC (19) PL (7) PL (5) PC ( 8) PL ( 6) PL (17) PL (12) 21 21 30 34 126 24 CL (42) CL (42) FE (48) UC (11) CP (29) CP (25) CY (18) CY (23) CL ( 9) FE (11) PC (19) PC (23) RF (12) CN ( 6) CY ( 8) CY (10) AT (15) AT (13) i I13 19 29 16 18 CN (24) EA (53) OC (39) OC (37) OC (73) CH (67) EA (20) CN (32) PC (16) CN (21) CH (12) OC (13) CL (19) HA ( 6) BN (12) HA (10) PC ( 4) PC ( 7) 11 15 17 21 26 29 AT (63) AT (97) AT (86) AT (78) PC (52) PC (50) CZ (30) CZ ( 1) pc ( 4) PC (10) CT (13) AT ( 9) HC ( 3) GV ( 1) CZ ( 3) BC ( 5) BC ( 6) BC ( 8) Ie , 23 i4 22 . 3 26 AT (36) AT (59) AT (41) AT (52) PC (21) PC (24) CZ (28) CZ (17) BN (39) OC (8) AT (19) AT (22) HA ( 4) GV ( 8) CZ ( 5) PC ( 8) O N (18) CN (12) 6 ?4 19 20 22 30 AT (46) BN (54) BN (63) AT (36) BN (42) BN (25) ON (45) AT (29) AT (19) GV (18) AT (18) AT (25) ME ( 8) 3C ( 5) PC { 8) PC (14) PC (16) PC (22) 14 16 20 24 23 25 AT (64) AT (67) AT (57j AT (53) PC (25) PC (30) ALL BN ( 9) BN (11) BN (24) PC (12) OC (15) AT (18) CZ ( 6) cv ( 8) PC ( 6) GV (5) BN (13) PL (10) Organism abbreviations: AT - Acarwtia tona adults & copepodids FE = fish eggs a larvae BC = barnacle cuprids GV = gastropod veligers BN - barnacle nauplii HA = unidentified harpacticoid copepods CH -� :ctrovages izlatua HC = iaicyclopFa spp. CL - cladocerans ME = medusae CN - copepod nauplii OC - ostracods CP - all other copepodids PC = Pamzoala:nus craarsiroatria CT - chaetognaths PL = polychaete larvae CY - unidentified cyclopoid copepods RF a rotifers CZ - crab zoeae UC - unidentified calanoid copepods EA - Euzrtemora affini3 5-4 identified in some collections. I. TAXONOMIC DIVERSITY Zooplankton samples collected during both extensive and intensive series showed large spatial and temporal variations in organism density and composition throughout the bay. Although the common species were widely distributed, each station was usually dominated by only a few taxonomic categories. Generally, the three most abundant categories in a sample comprised from 70 to over 90% of the total organisms (Tables 5-1 and 5-2). Results from the extensive series showed that the most seaward stations (MB and SB) were generally the most diverse with 15 to 31 zooplankton categories represented in any given sample (mean � S.D. : 24.1 � 5.0). SB consistently had at least 24 categories in each sample. Results from the other stations were highly variable with patterns of seasonal occurrence (Table 5-1). Upper estuary stations (PR, SR, PD, and WR) were generally the least diverse with 8-20 categories in each sample (mean � S.D. : 12.8 � 3.3). The middle bay stations (BI, TA, PS, TC, and EP) had 8-28 categories (mean � S.D. 15.2 � 5.1). The intensive series revealed a similar pattern. The upper station (US) was the least diverse (6-23 categories, mean � S.D. 16.1 � 4.3; Table 5-2). The middle intensive station (MS) had 14-34 categories, (mean � S.D. : 24.7 � 4.8), and the lower station (LS) had 5-5 16-30 categories (mean � S.D. : 25.0 � 3.9; Table 5-2). In general, taxonomic diversity increased during the winter when low numbers (I-10/m3) of freshwater species, especially cyclopoid copepods, occurred in the upper bay. This is in contrast to the findings for No Man's Friend and South Jones Creeks and North Inlet, where diversity was greatest during the warmer months when larval forms were introduced from high salinity areas (Allen et al., 1982; Barker unpublished). Most freshwater copepods never occurred in the vicinity of NMF and SJ in the middle bay. II. TOTAL ZOOPLANKTON Total zooplankton densities were generally much lower in the riverine extensive stations (PR, SR, PD, and WR with annual means of 6000 - 9500/m3) for most of the year, except when one or two species occurred at exceptionally high densities (Fig. 5-1; Appendix III. A). With the exception of EP, which generally had low total zooplankton numbers (annual mean : 7700/m3), all extensive stations had overall mean densities of 10000-13000/m3 (Fig. 5-1). The mean densities for most stations were similar to those reported for No Man's Friend and South Jones Creeks (8100/m : Allen et al., 1982), but were much lower than the North Inlet LTER collections (two-year mean = 20,000/m3: Barker, unpublished). Total zooplankton densities were greatest during the warmer months; the highest overall density (26,000/m3) occurred in May. Densities 5-6 TOTAL ZOOPLANKTON 18' IS ~~~I 16 ; 12 E 11 i 10 =l o 8I 0 6'- 24 0 2- I I I I i I I I I * w * PR SR PD WR BI TA PS TC EP MB SB ALL Fig. 5-1. Mean density (� 1 S.E.) of total organisms in zooplankton collections at 11 extensive series stations in Winyah Bay. Each mean is based on 14 samples taken over a 13 month period. A value based on all 154 collections is shown. 5-7 were generally about an order of magnitude lower during the winter months (Fig. 5-2). This was primarily due to the decrease in abundance or absence of dominant copepods such as Acartia tonsa and Parvocalanus crassirostris and the meroplankton. The exceptionally high total density rendered in May was the result of peak abundances of: (1) Acartia tonsa, Parvocalanus crassirostris, and meroplankton at most stations; (2) Eurytemora affinis and Halicyclops spp. at WR; and (3) Euterpina acutifrons and chaetognaths at SB. A similar temporal pattern of total zooplankton abundance was observed during the intensive cruises (Figs. 5-3, 5-4, and 5-5). Values for both surface and bottom tows were about an order of magnitude lower during winter months. Average total zooplankton numbers were higher at the bottom than at the surface (Appendix IV.A). At the upper station (US), total density was much higher at the bottom that at the surface throughout the year, except in winter (Fig. 5-3). Surface densities of total zooplankton ranged from 170/m3 in January to 1200/m3 in May, while bottom densities ranged from 150/m3 in January to 41800/m3 in May. The large difference during May was due to exceptionally high bottom densities in Acartia tonsa adults and copepodids (Appendix IV.B). At the middle station (MS), differences between surface and bottom densities were evident only in September 1981 and July 1982 when bottom numbers were almost double those at the surface (Fig. 5-4). This was due to much higher bottom densities of Acartia tonsa, Parvocalanus crassirostris, Oithona colcarva, polychnete larvae and gastropod veligers. 5-8 TOTAL ZOOPLANKTON 35' 30- 25. 20- o 15-9 51 0- SEP NOV JA MA M MAY JUL SEP ALL Fig. 5-2. Mean densities (+ 1 S.E.) of total organisms in zooplankton collections for each extensive series cruise in Winyah Bay. Each mean is based on 22 samples taken at 11 stations on each cruise. A value based on all 154 collections is shown; 5-9 TOTAL ZOOPLANKTON 40- 30- o~~~~~~~~~~~ - l _ 4 +~~~~~ _~~~~~~~~~~~ I I !~~~~~~~~ Cu U~~~~~~~~~~~~ I o - Ca 4 0 l- I 0. .3 SEP NOV JAN MAR MAY JUL SEP ALL Fig. 5-3. Mean densities (� 1 S.E.) of total organisms in zooplankton collections at the upper station (US) during the intensive series cruises in Winyah Bay. Surface (0) and bottom (') level values are shown for each of the seven cruises plus all cruises combined. 5-10 5-10 40 - TOTAL ZOOPLANKTON 35- 30- 25- 4-J 5 20- - I 10- 5- o0- I I I I I I I, SEP NOV JAN MAR MAY JUL SEP ALL Fig 5-4. Mean densities (1. S.E.) of total organisms in zooplankton collections at the middle station (MS) during the intensive series cruises in Winyah Bay. Surface (0) and bottom (e) level values are shown for each of the seven cruises plus all cruises combined. 5-1 5-11 TOTAL ZOOPLANKTON 45- 40- 4' 35- d~~~~~~~~~~~ 25- J~~~~~~~~~~~ J .5 4~~~ 20" 0 He z +~~~ s 15 4 > Fig. 5-5. Mean densities (I S.H.) of total organisms in zooplankton collections at the lower station (MN) during the intensive series cruises in Winyah Bay. surface (�) and bottom(') level values are shown for each of the seven cruises plus all cruises combined. ~~~~10'~~5-12 5- [ I I i I I I ! SEP NOV JAN MAR MAY JUL SEP ALL3 Fig.5-5.Mean densities (1 S.E.) of total organisms in zooplankton collections at the lower station (MN) during the intensive series cruises in Winyah Bay. surface (0) and bottom(') level values are shown for each of the seven cruises plusI all cruises combined. 5-12 At other times, there were no significant differences between surface and bottom concentrations. At the lower station (LS), differences between surface and bottom densities were less evident (Fig. 5-5). Bottom concentrations were higher only in September 1981 (44400/m3 vs. 13000/m3) and January 1982 (12000/m3 vs. 72/m3) due to greater numbers of A. tonsa, P. crassirostris, 0. colcarva, polychaete larvae and bivalve larvae. During other periods, surface densities were generally higher (Fig. 5-5). During the 48-hour sampling at Mother Norton, the bihourly trends of surface and bottom densities were similar, with peak abundance occurring shortly after high tides (Fig. 5-6). Although mean abundance of total zooplankton was higher for surface tows, the difference was not statistically significant (Table 5-3). Based dn this single 48-hour sampling period, no apparent relationship was evident between total abundance and the time of day (day/night). III. DOMINANT ZOOPLANKTON CATEGORIES The zooplankton community in Winyah Bay was dominated by relatively few copepod and meroplanktonic species (Table 5-1 and 5-2). Although mean densities and the presence or absence of other minor categories varied, the stations generally had similar dominant species on any cruise. Copepods comprised at least half of the total zooplankton at each station 5-13 6- Tidal amplitude -' 5- 4.; :`jv 4~ 4i boM 3- .r C 2- 0- 1200 1800 0000 00oo 12JO 180,0 oo6o 06�J 1200 50- U1 Total zooplankton a r~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ $4~i a40. - %~~~~~~~~~~~~~~~ a~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 30 a U U' o o4 . ci) 10- I~ 1100 1800 odoo 0660 1260 A 8bJ oo0o 0660 12b0 Fig 5-6. Mean densities of total zooplankton at surface (dotted) and bottom (;solid) during the 48 hour sampling at Mother Norton Shoal (September 18-20, 1982). ~~~ m -- as on M m - m Table 5-3 . Comparative abundance (mean #/m3 + S.E.) of zooplankton from surface and bottom tows taken during the 48-hour sampling at Mother Norton. Category SURFACE BOTTOM Acartia tonsa 3146.78 � 432.37 2495.56 + 421.89 Acartia copepodids ** 1719.65 � 154.45 1092.46 � 168.98 Paracalanus crassirostris 3371.75 � 325.63 3021.79 � 360.34 Euterpina acutifrons 1009.50 � 81.08 860.71 � 64.02 Oithona coZcarva 695.98 � 95.98 498.30 � 59.94 Pseudodiaptomus coronatus * 274.85 � 29.40 387.69 � 40.14 Other copepods 993.86 � 168.93 915.38 � 125.00 Copepod naupili 666.39 � 95.02 421.86 � 50.83 Other copepodids 447.72 � 64.30 467.62 � 77.94 [ Total copepods * 12326.48 � 788.58 10146.28 � 802.65 Barnacle nauplii * 4171.48 � 850.49 2336.57 � 382.76 Echinoderm larvae 822.98 � 207.13 715.48 � 189.81 Polychaete larvae 435.72 � 56.97 445.53 � 63.69 Gastropod veligers 744.00 � 137.98 1028.67 � 149.92 Crab zoeae 266.50 � 51.20 169.66 � 37.80 Other organisms 2904.42 � 243.46 3921.46 � 343.04 TOTAL ORGANISMS 23353.16 � 1625.47 20374.31 � 1224.38 NB. Categories with asterisks show significant differences in surface and bottom abundances: * p=O.05, ** p=O.Ol. 5-15 (Fig. 5-7) throughout the year (Fig. 5-8). Total copepods (represented as a percentage of the total zooplankton) ranged from 53% at SR to 95% at PS (Fig. 5-7); in the North Inlet LTER study, copepods comprised 70-85% of the total catch over a two-year period (Barker, unpublished). Some species of copepods were present throughout the year and they accounted for about 60% of total zooplankton in September to 90% in March (Fig. 5-2). Although they were not necessarily found in abundance at all stations, five copepod species (A. tonsa, P. crassirostris, P. coronatus, E. acutifrons, and O. colcarva) were year-round residents in the bay. Peak densities were observed during the spring and summer cruises. Other copepods appeared only during certain periods of the year. E. affinis and Halicyclops spp. were found only between January and July, while Centropages hamatus appeared only at the lower bay stations from November to July. The most common larval forms were barnacle nauplii and cyprids, crab zoeae, polychaete larvae, gastropod veligers and bivalve larvae. These groups exhibited distinct seasonal patterns in abundance, generally reaching peak densities in spring and summer. Other seasonal non-copepod forms included medusae, chaetognaths and appendicularians which occurred in warmer months, and cladocerans, ostracods and rotifers which appeared during colder months (Table 5-I and 5-2). Other planktonic organisms occurred sporadically and at very low densities. 5-16 Fig 5-7. Percent composition of zooplankton taxa at all 11 extensive series stations in Winyah Bay in 1981-82. The value for each taxa is a mean based on densities for all 7 cruises at that station. 100t ;- : : ; : 9-. - ,---- men=........ 80--i~ ~ .................. IIIIIIl.................. 70mmm~~~ ,................. ~ . :l 70I ::-: _i. : _i -- a ~ ~ ~ ~ .. '......... * - - - - - -,l O I60 I I .............' ......... �------- .----.-............... -.---JI I/J luyn ............... CD = , ,,,,, ......... .::::::::.:.:::: :::::::::- i lGU _ * ------- - ......... -------- .......... - ................. ......... " �:: '' ......... ........... o ......... ����'� e i...... ....�ew�.ee� ! Ql . ..... ......... ............... ........ z ...........------ 20: ......... ......... ..... . X ......... ����........... n-, � , '. ..��......' . 0. 5 3 110-.mm11 ......... '';;;- ''''111�� ��������~ PA... ..... ....Acartia Eurytemora barnacle others :. ......:.......... ......... PR SR PD WR BI TA PS TC EP MB SB Acartia s~0~ Parvocalanus other crab zoeae [TT.Acartia IIII11]1 Eurytemora barnacle others copepodids _IJJbarnacle nauplii Fig 5-8. Percent composition of zooplankton taxa on all 7 extensive series cruises in Winyah Bay in 1981-82. The value for each taxa is a mean based on densities for all 11 stations on that cruise. 100-- 90- 80- 80- n I mlmlll 111111111- �.1 _i 50::_ ............ 5" o 50 - .. . . . ,U. . : . n DU.. .......[ 50 Pi g -... . .......... . ........... .......... . ..... . .. ......_ . ........ *le~eele. .*. . . ...� . � . e. oo cl ; .................:.. .......... 3 ..-- ----- .......... ........ 40 - 1 � ' � � � � �� ' '' ' " '' '' ''' ' '' ' ��20 �- ONl .. ..........,,,,,,~ -,61 luflllu- l :,11' SEP NOV JAN MAR MAY JUL SEP ALL Acartia U Parvocalanus other crab zoeau adults O copepods Acartia Eurytemora ~ barnacle others copepodids nauplii - m - - - --- ~~~~~~~~~o m - m - IV. COPEPODS A. Acartia tonsa Acartia tonsa dominated the Winyah Bay ecosystem. It accounted for nearly 60% of all zooplankton collected during the study (Table 5-1). Mean densities which ranged from 1500/m at SB to 11000/m3 at TA were similar to values reported for No Man's Friend and South Jones Creeks (Allen et al., 1982). Adults and copepodids of A. tonsa, when present, generally comprised a significant portion of total zooplankton at all stations (Table 5-1; Fig. 5-7). Average annual abundance of the species was generally higher at the middle bay stations, where adults and copepodids comprised about 90% of all zooplankton at TA and PS and 60 to 70% at BI and TC (Fig. 5-7). The abundance of A. tonsa ranged from 15-20% of total zooplankton at the seaward stations (MB and SB) to 40-70% at the riverine stations (PR, SR, PD, and WR). A true euryhaline species with broad salinity tolerance range, A. tonsa is generally more abundant in bays and rivers than in oceanic waters (Grice, 1960; Lance, 1963; Bowman, 1971; Sandifer et al., 1980). Although A. tonsa was present year-round (especially at the lower bay stations), distinct seasonal variations in abundance occurred. It was absent at upper bay stations and was rare at the other stations during winter; highest densities occurred at all stations in spring and summer (Fig. 5-8; Appendix III.C,D). A warm-water species, A. tonsa comprised less than 5% of the zooplankton during winter months (Janu�ry- 5-19 March), but accounted for 40-80% during other months. These temporal patterns are similar to those reported for other estuarine systems (Sutcliffe, 1948; Woodmansee, 1958; Lonsdale and Coull, 1977; Sandifer et al., 1980; Allen et al., 1982). During the intensive sampling series, similar spatial and temporal patterns were observed for A. tonsa (Table 5-2). Both adults and cope- podids reached peak densities at the three stations during the spring and summer months. With few exceptions, A. tonsa densities were higher at the bottom than at the surface during these months of peak abundance (Appendix IV.B). Surface densities were 1300, 3000 and 800/m3 at US, MS and LS, respectively; corresponding bottom concentrations were 6100, 4000 and 2200/m3. In contrast to this pattern. a series of paired t-tests showed surface densities of Acartia copepodids during the 48 hour study to be significantly greater than bottom densities. Additionally, higher densities of adult Acartia occurred at the surface (Table 5-3). Com- bined adult and copepodid densities were significantly higher at the surface. Both surface and bottom peak abundances generally occurred shortly before low tides (Fig. 5-9). B. Eurytemora affinis .~~~~~~~~~~ This calanoid copepod comprised 5.5% of all zooplankton collected in the study, making it the second most abundant copepod in the Winyah Bay Estuary. When present, it was common at the upper and middle bay 5-20 6- Tidal amplitude 5- 4; n 3. -H bo I. 1 2. 0- O- 1'8Is 2'4 A :?2 HI 6 102 Lu r;12.. All Acartia tonsa 8- U 10- Ps. 6- jf%� J~ J I JJ � o o ln",, Z.' 8'. ,\ �,.,'i a i C) 4 �- .I O*'~~~~~~~~~~~~~~~~~~~~~~~~~----I 0 " o * I % I 1200 1800 2400 600 1200 1800 2400 600 1200 Fig 5-9. Mean densities of all Acartia tonsa (adults and copepodids) at surface (dotted) and bottom (solid) during the 48 hour sampling at Mother Norton Shoal (September 18-20, 1982). stations and rare at the most seaward stations (Appendix III.E). Characteristic of fresh or less brackish waters, E. affinis was the most dominant copepod at PR and WR, where it accounted for 28% and 38% of all zooplankton, respectively (Fig. 5-7). It reached a peak density of 16000/m3 at WR and 9000/m3 at PR. E. affinis also com- prised a sizable percentage of all zooplankton at SR, PD, BI and TA, where it was the second most dominant copepod (Fig. 5-7; Table 5-1). This large calanoid copepod was only occasionally collected in low densities at the lower bay stations (Appendix III.E). Its ocurrence in low salinity waters was also noted at No Man's Friend and South Jones Creeks (Allen et al., 1982) and in North Inlet (Barker, unpub- lished). A distinctly seasonal species, E. affinis first appeared at all stations (except WR) in January and reached peak abundances in late spring and-early summer (Fig. 5-83 Appendix III.E). It became the most dominant organism in March when it accounted for over 60% of all zooplankton and was the second most abundant copepod in the system in July (Fig. 5-8). During the intensive series, E. affinis most commonly occurred between January and July at the upper station (US), where it was the dominant copepod in March (Table 5-2). With the exception of a few individuals taken in bottom tows at MS in January and March, it was not collected at MS and LS (Appendix IV.C). At US, during peak abundance in March, bottom density (3700/m3) was much higher than the surface density (600/m3). 5-22 C. Parvocalanus crassirostris Overall, P. crassirostris was the third most abundant copepod in the Winyah Bay Estuary. It comprised 5% of the total zooplankton on an annual basis. This is in contrast to observations at No Man's Friend Creek, South Jones Creek and North Inlet where it was the most abundant copepod (Allen et al., 1982; Barker, unpublished). P. crassi- rostris was generally most abundant at the stations nearest the ocean and was either rare or absent at the riverine stations (PR, SR, PD, WR) (Fig. 5-7). At station SB, P. crassirostris was the most abundant copepod, accounting for nearly 30% of all zooplankton. It was the se- cond most abundant copepod at MB and comprised large percentages at BI, PS, TC, and EP. Densities at MB and SB were usually up to an order of magnitude higher than those at the other stations (Appendix III.F). Although densities were generally low during winter months, P. crassirostris was present year-round, especially at the most seaward stations (Fig. 5-8). With the exception of May collections at SB when mean abundance was 13100/m3, mean densities during the warmer months ranged from 1000 to 3400/m3. These densities were similar to values reported for No Man's Friend and South Jones Creeks (about 3200/m3: Allen et al., 1982), but they were much lower than those at North Inlet (15 - 20,000/m3: Barker, unpublished). Concentrations at the lower bay stations during winter months were an order of magnitude lower than during other periods. On the intensive cnuises, P. crassirostris was absent or rare at 5-23 the upper station (US) and had highest densities at the lower station (LS) during all months (Appendix IV.C). When abundant, the species comprised similar proportions of total zooplankton in both surface and bottom tows (Table 5-2). On most cruises, surface and bottom densities were equivalent (Appendix IV.C). A similarity between surface and bottom densities was also ob- served during the 48-hour sampling series at Mother Norton (Table 5-3). Peak densities tended to occur shortly after high tides (Fig. 5-10). D. Pseudodiaptomus coronatus P. coronatus, a relatively large calanoid species, was generally found at the lower bay stations (primarily TC, EP, MB and SB) where it comprised about 2%. of all zooplankton at each station (Appendix III.G). At peak abundance, mean densities only ranged from 100 and 900/m3. These were similar to values reported for No Man's Friend and South Jones Creeks (Allen et al., 1982). Although it is considered a fall-winter species in the southern part of its range (Sutcliffe, 1948; Woodmansee, 1958; Sandifer et al., 1980), P. coronatus disappeared in winter form all stations except MB and SB where it was rare. Peak densities occurred in late spring and fall at most stations., The exception was at SB where highest concen- trations were recorded during July. At the mouth of North Inlet, high densities occurred frmu late winter through summer (Lonsdale and Coull, 1977). 5-24 m m m -m m - m - - ~6 -Tidal amplitude 6- 5- 4 3- 2 1- 0- lm8 ll4 HOUR 2 2 { 2'4 f2 HOUR 8- Ln Parvocalanus crassirostris I' Ul Ln 6-, 1 I / ,I1 *: . /1,a I a\/ 2~~~~~~~~~~~~~~~~~~~~~~~~ Fi -0 en este f avclns rsioti atsrac (dttd andbtosld drgh4husmigtohNroSa(ee2 ,1 a \ 2 - __ ~ ,,'I :, ;! 2-~\ .-" -. -- ......' - T :/ I ,* r ~ ~~~~~~~~~~ 5 I m a I I I 1200 1800 2400 600 1200 1800 t2400 600 1200 Fig 5-10. Mean densities of Parvocalanus crassirostris at surface (dotted) and bottom (solid) during the 48 hour sampling at Mother Norton Shoal (September 18-20, 1982). Pseudodiaptomus coronatus showed some degree of vertical stratifi- cation. Densities were consistently higher at the bottom than at the surface during all intensive cruises (Appendix IV.D). This pattern was shown to be statistically significant during the 48-hour series at Mother Norton (Table 5-3). Jacobs (1961) found greatest densities of the copepodids of P. coronatus at the bottom of Georgia estuaries and contended that this species was not truly planktonic since it attached to suspended material. E. Euterpina acutifrons Euterpina acutifrons was the most abundant pelagic harpacticoid in the Winyah Bay Estuary. It primarily occurred at the most seaward extensive stations and was absent or rare at the uppermost stations (Appendix III.H). With peak densities of 1300 - 2500/m3, E. acutifrons comprised 2% and 4% of the total zooplankton at MB and SB, respectively. Peak abundance was similar to that at North Inlet (Barker, unpublished), but it was higher than that at No Man's Friend and South Jones Creeks (Allen et al., 1982). E. acutifrons was absent or rare at all stations during the winter months (January-March) and in July. It reached peak densities of up to 2500/m3 at the lower estuary stations in spring. In contrast, peaks of abundance at NMF and SJ Creeks were in late fall (Allen et al., 1982). Peaks at North Inlet occurred in summer and early fall (Lonsdale and Coull, 1977; Barker, unpublished). 5-26 During the intensive series, E. acutifrons was also most abundant at the most seaward station (LS) throughout the year (Appendix IV.D). It peaked in abundance (2000/m3) in fall at both the lower (LS) and middle (MS) stations. No clear-cut pattern in vertical distribution was evident during the intensive and 48-hour series (Table 5-3). F. Oithona colcarva The most abundant cyclopoid copepod in the lower estuary, 0. colcarva primarily occurred at the most seaward stations and appeared only sporadically at riverine stations (Appendix III.I). With peak 3 densities of 1000-1300/m3, it was the third most abundant copepod at MB and SB. It accounted for about 2% and 6% of the total zooplankton at MB and SB, respectively. 0. colcarva was present at the most seaward stations year-round. Its highest abundance was in late winter - early spring (March) at the SB station and during fall (September-November) at the other stations (BI, TA, PS, TC, EP, MB). Similar temporal patterns of abundance were observed at NMF and SJ Creeks (Allen et al., 1982) and at North Inlet (Lonsdale and Coull, 1977; Barker, unpublished). 0. colcarva was also the most dominant organism during March at stations TC, MB and SB, where it comprised 27-41% of the total zooplankton (Table 5-1). During the intensive series, peak abundance of 0. colcarva was observed in early spring at LS (14000/m3) and in fall at MS (1500/m3) 5-27 (Appendix IV.E). It occurred only at US in March, July, and September at relatively low numbers (< 360/m3). Although at LS during the spring peak, surface abundance was nearly twice that at the bottom, there was no consistent difference between surface and bottomdensities. During the 48-hour series, surface and bottom densities (500-600/m3) were also similar (Table 5-3). There was no apparent relationship between Oithona abundance and tidal or daylight conditions. G. Halicyclops spp. Copepods of the genus Halicyclops were the most dominant cyclopoids at the less saline, upper bay stations. During periods of peak abundance, Halicyclops was one of the three most abundant categories at PR, SR, PD and WR (Table 5-3). This copepod was absent in late summer-fall (September-November), appeared in January, and reached a peak abundance of 2300/m3 in late spring and summer (May-July) 6Appendix III.J). These cyclopoids were collected at similar densities in surface and bottom tows at the upper station on spring and summer intensive cruises (Appendix IV.E). V. MEROPLANKTON A. Barnacle larvae Among the meroplankton, larval stages of barnacles were the most 5-28 abundant larvae in the system. They were often one of the three most abundant categories in the collections (Tables 5-1 and 5-2). The two planktonic developmental stages of barnacles had similar spatial and temporal distributions. Barnacle nauplii were generally found at all stations, and comprised from 2% to 32% of mean zooplankton densities (Fig. 5-7). They were present in the estuary throughout the year, except in January-March when they occurred in low numbers (<50/m3) only at the most seaward stations (Fig. 5-8; Appendix III.K). Peak abun- dance (about 19000/m3) occurred in fall at most extensive stations. In contrast, densities of barnacle nauplii were highest from December through April in NMF and SJ Creeks (Allen et al., 1982) and between April and August in North Inlet (Lonsdale and Coull, 1977). Differ- ences may be related to the different spawning times of the various species which occur within the system. Barnacle cyprids were generally less abundant than the nauplii and sometimes constituted a sizable percentage of total organisms at some stations (Tables 5-1 and 5-2). Highest densities (from 600 to 2200/m3) were found during spring at most stations and in fall at the other stations (PR, SR, EP) (Appendix III.L). Cyprid densities were generally higher than those reported by Allen et al. (1982) for No Man's Friend and South Jones Creeks where peaks were around 200/m3. With the exception of the September intensive collection in the upper bay, barnacle nauplii densities were higher at the surface than at the bottom (Appendix IV.F). At Mother Norton, barnacle 5-29 nauplii densities were higher at the surface than at the bottom (Appendix IV.F). At Mother Norton, barnacle nauplii were signi- ficantly more abundant at the surface (Table 5-3). Cyprid densities were usually higher at the bottom. B. Crab zoeae Crab zoeae were common (up to 3600/m3) at all stations (Fig. 5-7) during certain times of the year (Appendix III.M). They were most abundant at PR where they accounted for 10% of all zooplankton. When presenit, they were usually among the most abundant groups in the collections (Tables 5-1 and 5-2). Zoeae occurred only during late spring and summer in both the extensive and intensive series. Densities tended to be higher at the surface than at the bottom (Appendix IV.G). During the 48-hour sampling, the difference between surface and bottom densities was not significant (Table 5-3). C. Polychaete larvae Polychaete larvae were found throughout the year at all extensive stations. Maximum densities were about 1400/m3 (Appendix III.N). From spring through fall, they comprised one of the three most abun- dant categories at the riverine stations (Table 5-1). During the intensive series, polychaete lar ae were generally 5-30 more abundant at the bottom than at the surface at US and MS (Appendix IV.G). Polychaete larvae densities were generally highest at LS; how- ever, no consistent pattern between surface and bottom abundances could be discerned at this station. At Mother Norton,surface and bottom densities (about 440/m ) were not significantly different (Table 5-3). D. Molluscan larvae Molluscan larvae also showed a distinct seasonal pattern of a bundance. Gastropod veligers occurred from spring to early fall in the uppermost and lowermost extensive stations; they were rare or ab- sent at stations TA and PS throughout the year (Appendix III.0). During peak densities in summer and fall, the most seaward stations had the greatest abundance of veligers (up to 2500/m3 at the exten- sive stations; 9000/m3 at the intensive stations). During these periods, bottom densities of gastropod veligers were up to one order of magnitude greater than those at the surface (Appendix TV.H). Bottom densities were also higher during the 48-hour series; however, the difference was not statistically significant (Table 5-3). Bivalve larvae were most common at the seaward stations (Appendix III.P). Peak densities (70-470/m3) occurred during May at all lower bay stations (TC, EP, MB, SB). They were only sporadically collected at the upper stations during spring and summer at densities less than 20/m3. In the intensive series, bivalve larvae were found throughout 5-31 most of the year at MS and LS (Appendix IV.H). Peak abundance was recorded during July at both MS (180/m ) and LS (1800/m ); bottom densities were usually higher than surface densities. In summary, the zooplankton community in Winyah Bay was dominated by only a few species of copepods and the meroplanktonic larval stages of benthic invertebrates. In most cases, three taxonomic categories accounted for up to 90% of all organisms present. Taxonomic diversity was relatively low at all stations. Although there were distinct differences in patterns of occurrence and abundance, on each cruise the same taxa occurred at most stations in the estuary. While the most common groups occurred throughout the year, certain copepods and most larvae were seasonally abundant. Many of the components of the Winyah Bay zooplankton play impor- tant roles in estuarine trophic dynamics, especially as food for young fishes and crustaceans. The zooplankton also serve as source of re- cruitment for benthic shellfish or fish populations. Perturbations adversely affecting the zooplankton constituents will ultimately in- volve other major components of the bay ecosystem. This is particu- larly significant since there are so few major taxa comprising the zooplankton community. Whatever affects the key species would surely affect the entire zooplankton community and subsequently other popula- tions which depend upon the zooplankton for food sources. Destruction of year classes of fish and invertebrate larvae would have serious long term repercussions. 5-32 CHAPTER 6. MOTILE EPIBENTHOS Organisms collected with an epibenthic sled (365 gm) include small crustaceans and fishes which either spend their entire lives within a few centimeters of the bottom or occur there only as devel- opmental stages for relatively short periods of time. Since all of these organisms are motile and aggregative to some extent, the com- position and abundance of the motile epibenthic community is highly variable in space and time. Although little information is available on the spatial and temporal distributions of motile epibenthic orga- nisms in estuaries, it is clear that they play very important roles in these ecosystems. In this chapter, we present the first level analysis of data based on more than 450 epibenthic sled collections taken throughout Winyah Bay over a 13 month period. More than 200 species of invertebrates and fishes have been collected with epibenthic sleds in the Winyah Bay - North Inlet area. Many of these forms only occur as incidental catches in the sled because they are either too large, small, or motile to be effectively collected with this sampling device. For this reason, copepods, crab zoeae, and other small invertebrates generally considered to be planktonic are not discussed in this chapter. Mollusks (clams and snails), polychaete worms, bryozoans, and other macroinvertebrates which are classified as benthic (living in the sediment) or fouling (attached to hard substrate) organisms are also deleted from the analysis. Softbodied invertebrates such as chaetognaths, medusae 6-1 (jellyfish), and ctenophores (comb jellies) often dominated sled catches, but they were usually not enumerated in the collection analysis. Shrimps, crabs, and fishes more than about 20 mm in length are generally able to avoid the sled, so incidental catches of these individuals were not considered in the final analysis. Most of the organisms collected were small (< 20 mm) crusta- ceans and fishes. Although some of the most common forms were mysids, amphipods and other small adult crustaceans, many were developmental stages of more familiar shrimps, crabs, and fishes. Thus, the motile epibenthos represents a community comprised of larval crustaceans and fishes as well as important prey species for these and other estuarine predators. The taxonomic categories considered here are identical to those discussed in our report on earlier studies of No Man's Friend (NMF) and South Jones (SJ) Creeks (Allen et al., 1982). The read~er should refer to this volume for additional information on these taxa (including drawings) and for specific scientific literature references. In the present report, summaries of the spatial and temporal distribu- tions of each of the major taxa collected in Winyah Bay comprise the first sectionand sections which address trends for total epibenthic organisms and the results of field experiments on sampling effective- ness follow. In the first section, entries for taxonomic groups in- clude: (1) a summary of cruise to cruise variation based on the ex- tensive series, (2) a summary of the spatial distribution based on the extensive series, (3) general trends with comparisons to NMF, SJ, 6-2 and the 6 Winyah Bay stations sampled in 1980-81, (4) a summary of spatial and temporal patterns within the intensive series, (5) results of intensive series experiments to determine patchiness on the bottom in 3 regions of the Bay, and (6) a summary of changes in abundance on the bottom and throughout the water column within one tidal cycle. A. MYSIDS Mysid shrimps represented the single most important group of organisms collected during the study. Neomysis americana was the most common species in the lower bay and the only mysid collected at salinities less than about 25 ppt. It was present in Winyah Bay and nearshore coastal waters year round. Mysidopsis bigelowi was common and sometimes outnumbered N. americana in collections from the lower bay, but only during the warmest months. Promysis atlantica, Metamysidopsis swifti, Bowmaniella floridana, and Brasilomysis castroi only occurred during summer in high salinity areasand none was abun- dant on any cruise. All species are included in the analysis of the spatial and temporal distribution within Winyah Bay. Mysids comprised more than half of all organisms collected on the September 1981, November, and March cruises (based on the mean of all 11 extensive series stations (Fig. 6-1)). In November, mysids accounted for 80% of the catch. In January, when mysids were least abundant in the system, they accounted for 15% of all organisms collected (Fig. 6-1). 6-3 Fig. 6-1. Percent composition of major epibenthic taxa for each cruise in Winyah Bay. The value for each taxa is a mean based on densities of all It extensive series stations on that cruise. 100 90 80 70 -~~~~~~~~Inv P,50 o\ f-~~~~~~~~~~~~~~~~~~~~~~~f-r 40 o~~s T3~-j EZZOcE 'u3- .~~~~~~~~~~~~~~~~~~~~'TA 40 O __ 30~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 20 ZT = = =c Lic j~ocbjcjtt L~ft OlI=~a f~M ~tflI2 ~~~~~~~~~~~~~~~~~~I 0~-~ SEP NOV JAN MAP , MAY JUL SEP MYSI DS jjjjjjjFISH LARVAE CRAB MEGALOPAE AMPHIPODS SHRIMP LARVAE OTHERS - 1 >jc iOS~ - - 30 - Highest mysid densities were in September 1982 (about 11/m ), and moderate densities were observed in November and May (about 6/m3). Densities of less than l/m3 were found in January (Table 6-1). The station with the highest density for all cruises combined was EP with 14/m3. SR had the second highest densities (about 10/m3), most stations had mean values of 3 to 7/m3, and PR had the lowest densities (0.1/m3) of all stations (Table 6-2). Mysids made up about 50% of the catch at 7 of the 14 stations sampled in the study (Fig. 6-2). They accounted for less than 10% of all organisms only at PR, PD, and PS. The largest collection of mysids was 51/m3 at EP in January. They were also very abundant at SR in September 1982 (42/m3), (Appendix V. A.). Most collections yielded densities of less than 5/m3. Differences between adjacent stations or consecutive cruises were often one to two orders of magnitude. No mysids were collected in the rivers in January or March when water temperatures and salinities were lowest. However, moderate densities were determined at SR in July when the bottom water was about 60/oo. In general, more mysids were found in brackish (Mud Bay) and high salinity areas, especially during winter and spring. The overall seasonal trend for the 11 station extensive series (1981-82) was very similar to that in the initial (6 station) study in the Bay during 1980-81, but mysids were up to 10 times more abundant during the earlier study (Allen, et al., 1982). 6-5 Table 6-1. Mean number of organisms per cubic meter plus or minus one standard error for each cruise in the Extensive Series from September 1981 through September 1982. Each value is a mean for collections made at all 11 stations on each cruise. SEP NOV JAN MAR MAY JUL SEP Total Organisms 6.1 + 1.6 7.6 � 3.3 4.8 + 2.0 8.3 � 2.6 19.4 + 4.3 10.5 + 3.0 25.3 + 9.2 Mysids 3.4 � 1.2 5.9 + 3.2 0.7 + 0.3 4.3 + 2.4 6.2 + 1.8 2.2 + 1.0 10.5 + 3.1 Amphipods 1.0 + 0.3 1.2 + 0.5 4.0 + 1.2 2.5 + 0.8 1.1 + 1.0 5.5 + 2.2 13.0 � 0.2 Shrimp Larvae 1.0 + 0.4 0.1 0.1 0.8 � 0.3 2.4 + 0.3 2.4 + 0.9 1.2 � 0.2 Postlarval Penaeids 0.1 0.1 0 0 0.5 + 0.1 0.1 0.1 Crab Megalopae 0.2 0.1 0 0.1 0.1 0.1 0.1 Fish Eggs 0.1 0.1 0 0.1 5.9 + 2.2 0.1 0 Fish Larvae 0.1 0.2 0.2 1.3 � 0.5 2.7 � 1.0 0.1 0.1 - _ am _ _ go _ _ _ ___s -mm ami _M_ Am m mm <ram - m gm am m -_ mm Table 6-2. Mean number of organisms per cubic meter plus or minus one standard error for all 11 Extensive and 3 Intensive stations. Extensive values are means of 14 collections and Intensive values are means of 60 collections taken during the 13 month study. + indicates presence at less than 0.1 per m3. PR SR PD WR US BI TA Total Organisms 3.5 + 1.5 14.9 � 5.0 30.6 � 14.1 5.2 � 2.6 5.2 � 1.0 10.2 � 4.2 18.1 � 4.8 Mysids 0.1 9.9 � 4.2 2.7 � 1.1 3.0 � 1.9 2.7 � 0.6 4.9 � 2.6 6.3 � 2.7 Amphipods 2.7 � 1.5 1.8 � 0.7 25.9 � 13.2 0.7 � 0.2 0.9 � 0.3 2.1 � 0.8 4.1 � 0.6 Shrimp Larvae 0.5 � 0.2 2.9 � 1.5 1.1 � 0.5 1.2 � 0.6 1.4 � 0.3 0.7 � 0.3 0.5 � 0.1 Postlarval Penaeids 0 0.1 0.2 � 0.1 0.1 0.1 0.1 0.8 � 0.5 Crab Megalopae + 0.1 0.2 � 0.1 0.2 � 0.1 0.1 + + Fish Eggs + + + + 0.1 2.0 + 1.4 5.0 + 3.5 Fish Larvae 0.2 � 0.1 0.1 0.4 � 0.2 0.1 0.1 0.2 + 0.1 1.3 � 0.5 Table 6-2. Continued PS TC MS EP MB SB MN Total Organisms 7.0 � 1.4 5.8 � 1.4 12.3 � 2.9 16.0 � 5.1 12.9 � 4.5 4.5 � 1.0 9.0 � 1.2 Mysids 0.6 � 0.1 3.1 � 0.3 7.0 � 1.7 13.5 � 2.4 6.1 � 1.8 2.0 � 0.3 2.1 � 0.3 Amphipods 3.4 � 0.8 0.4 � 0.1 0.5 � 0.1 0.7 � 0.2 2.3 � 0.6 0.4 � 0.1 0.6 � 0.2 Shrimp Larvae 0.8 � 0.1 1.0 � 0.2 1.0 � 0.2 0.8 � 0.1 0.7 � 0.1 0.8 � 0.2 1.4 � 0.3 Postlarval Penaeids 0.1 + + + + + + Crab Megalopae + 0.1 0.2 � 0.1 0.2 � 0.1 0.1 0.3 � 0.1 1.3 � 0.2 Fish Eggs 0.3 i 0.1 0.7 � 0.2 2.6 � 0.9 0.5 � 0.2 0.6 � 0;2 0.1 1.9 � 0.6 Fish Larvae 1.6 �+ 0.3 0.2 � 0.1 0.6 � .0.1 0.1 2.5 � 0.8 0.5 � 0.1 1.4 � 0.4 t 0' _ 1 A _ _ -' lj - am * _ _ i _s - A rn -, man - m ~ Fig. 6-2. Percent composition for major epibenthic taxa for each station in Winyah Bay. The value for each taxa is a mean based on densities from all 7 extensive cruises at that station. 100 90 LLLM 80 - .j60-_ __ g~~~~~QtZ3ID~~~~~-7"~ o - -~ O 5 0 - _ _ _ _ _ _ _ _ 40- * ~ _ $4~~~~~~~~~~~~_ ;1:K14- a~!UC,-( --- EZ 30 - E= MV0 cz 'i~=Ir- 1%1 In~~~s ~ ~ 0-, I = = 20 - E. S u lZ1 z ljc[ _ 44o3'~I--" C IC 10 I Cf ncjE E: ~ ~ ~ ~ ~ _ -u =L.J-tZ~ __~~-�_- ,, -~'~ -"""~~ ;aTI PR SR PD WR RI TA PS TC EP MB SB ~~ ~MYSIDS IIIIWIIIFISH LARVAE CRAB MEGALOPAE W ~~AMPHIPODS SHRIMP LARVAE OTHERS Although there are significant differences in abundance from year to year, a seasonal trend with a winter peak was observed during both years of sampling in the lower bay and at NMF and Si. A similar seasonal trend was seen in the intensive series. overall densities were highest at MS (Fig. 6-3, Appendix VI. A.), but this is primarily related to the occurrence of densities ofU up to 96/rn at MS in May. These high numbers occurred in the first two 3 minute tows, but not in any of the subsequent 3, 6,1 or 9 minute tows. Such variation is attributed to the patchy 1 occurrence of mysids on the bottom. Additional statistical tests will be performed on these data,. but the preliminary analysis4 indicates that mysids are widely distributed in low densities (especially in the middle and lower bay) and that high density aggregations occur in most areas for undetermined intervals that may range from hours to weeks. I Large short-term fluctuations in mysid densities were evident during the Special Series at MN in September 1982. Densities ranged from less than I to 20./rn3 during the 5 hour study (Table 6-3). Mysids were more abundant in bottom than surface samples during all stages of the tide (Table 6-3). They always comprised a greater proportion of the catch at the bottom, although during turbulent strong tidal velocity conditions, 16% of the surface* catch was mysids (Table 6-3). The density of mysids in all gear increased with increasing current velocity (Table 6-4). 6-10 Fig. 6-3. Mean densities (+1 S.E.) for 3, 6, 9 minute and all sled collections at 3 intensive series stations in Winyah Bay. Values are means of all 7 cruises. 30 _ X 25 TOTAL EPIBENTHOS C; 20 X 15 10 I I I I , I I , I I I 3 6 9 all 3 6 9 all 3 6 9 all UPPER MIDDLE LOWER 20- t, 18 - |MYSIDS 16 14 - 14.0 + 7.0 ci .4 a 12 2 cQ 10 - Qam *0 8 6I � 2- 4 4 4 + I I I I I I I I I I I I 3 6 9 all 3 6 9 all 3 6 9 all UPPER MIDDLE LOWER 6-11 Table 6-3. Percentage of the total catch that each taxonomic group camprised during slack, moderate, and strong current conditions at MN on September 17, 1982. Values for surface (upper) and bottom (lower) 365 gm closing nets are given for each taxa. Slack Moderate Strong Mysids 1 1 16 35 2 21 Amphipods 6 16 7, 6 16 3 Shrimp Larvae 27 17 18 18 7 12 Crab Megalopae 21 1 1 3 3 1 Fish Larvae 47 10 1 3 6 1 Chaetognaths 10 24 38 23. 51 52 Lucifer 8 9 7 12 3 4 Isopods 1 22 8 0 11 5 Others 7 0 4 0 3 1 6-12 Table 6-4. Summary of occurrence of taxonomic groups in a variety of sampling gear during the Special MN series on September 17, 1982. Density at surface(s) Range in density relative to bottom at Change in density Taxa (#/mj) for all gear all stages with increase current Total Organisms 7.2 - 66.4 B > S increase Mysids 0.2 - 19.8 B > S increase Amphipods 0.3 - 9.7 B > S no change Shrimp larvae 1.4 - 10.4 B > S no change Crab megalopae 0.1 - 1.2 B > S increase Fish larvae 0.1 - 6.9 S > B decrease Chaetognaths 1.4 - 33.8 B > S increase Lucifer 0.7 - 7.8 B = S no change Isopods 0.1 - 11.2 B > S increase B. AMPHIPODS This group of small pericarid crustaceans was the second most important group of motile epibenthic organisms in Winyah Bay. Due to the amount of time necessary to identify all indi- viduals to species, we were only able to deal with amphipods on the total amphipods level. Gammarids of the genera Batea, Coro- phium, Erichthonius, Microprotopus, Unicola, Gammarus, Listriella, Elasmopus, Melita, Stenothoe, and Synchelidium have been identi- fied from various sled collections, but no specific information on occurrence is available at this time. Caprellids of the genera Caprella and Paracaprella were also identified. All comments on distribution are for total amphipods. Amphipods were frequently the most abundant taxa in sled collections and often dominated the catches in the upper and middle bay (Fig. 6-2). More than half of all organisms collected in January, July, and September 1982 were amphipods (Table 6-1). High- est densities were in September 1982 (13/m3). During all other months densities were from 1 to 6/m3 (Table 6-1). Overall densities were highest at PD (26/m3) (Table 6-2). No other station had mean values greater than 4/m3. Amphipods accounted for more than 50% of the catch at PR, PD, and PS (Fig. 6-2). It is interesting that these are the 3 stations at which mysids were least important. Amphipods comprised less than 10% of the catch at most other stations. 6-14 The two largest catches were at PD in July (33/m3) and September 1982 (134/m3) (Appendix V. B.). The latter was the highest density of any epibenthic organisms determined in the study. In the previous study (Allen, et al., 1982). amphipods were generally more abundant in the upper bay, especially at the river stations. Densities at NMF and SJ were less than 1/m3 throughout the year. At the intensive series stations, overall densities were less than 1/m3 (Fig. 6-4). They were somewhat higher at US than MS and MN; however, none were collected at US.during November (Appendix VI. B.). Despite low temperatures and salinities, numbers of amphipods occurred in the US in Jarnuary. Variability between consecutive 3, 6, and 9 minute collections was high, but there did not appear to be significant differences between tows of different lengths at any station when data from all cruises were combined. Further testing will reveal the extent of patch- iness. The amount of variation over only 5 hours at MN (< I to 10/m3) was greater than that between most cruises (Table 6-3). Densities were greater on the bottom than near the surface (Table 6-3). Amphipods comprised equivalent proportions of the surface and bottom catch at slack and moderate tides, but like mysids, they were more important in surface catches during strong tidal current conditions (Table 6-4). 6-~ 15 Fig. 6-4. Mean densities (�1 S.E.) for 3, 6, 9 minute and all sled collections at 3 intensive series stations in Winyah Bay. Values are means of 7 cruises. 1.6 . A 1.4- AMPHIPODS X 1.2- 1.0' ' 0.8' 3 0.6 0.4.- 0.2' I I I I i I I I I 1 3 6 9 all 3 6 9 all 3 6 9 all UPPER MIDDLE LOWER 1.6' 1.4 - CRAB MEGALOPAE . 1.2 U 1.0' 0.8 0.6' 0.4l 0.2 4 t 1 I I I l I I I I I I I 3 6 9 all 3 6 9 all 3 6 9 all UPPER MIDDLE LOWER 6-16 Since many species of amphipods live in the sediment or are associated with fouling organisms (sponges, hydroids, etc), the epibenthic sled does not effectively sample all amphipod populations. All values are probably large underestimates of actual amphipod densities at most locations; however the trends described here are probably representative of the groups' distribution on open bottom of Winyah Bay. Amphipods are particularly abundant ( > 100/m3) along shore zones, docks, and wherever hard substrates occur. There is a high diversity of species especially in the lower bay during the warm months, and other sampling gear and locations must be used to provide more specific information about this group. In general, amphipods are major sources of food for most predaceous fishes in the estuary. C. ISOPODS Isopods are also pericarid crustaceans that, with the exception of few species such as Aegathoa oculata, are closely associated with sediment and debris on the bottom. Crawling and burrowing forms such as Edotea montosa, Acinus depressus, Cassidinidea lunifrons, Sphaeroma spp. and Chiridotea spp. were identified from the collections. Aegathoa oculata was by far the most widely distributed species within the system. The patterns described are for total isopods. Isopods occurred in only about 30% of all collections and, 6-17 generally, only a few individuals were taken. The highest density was at SB in September 1981 (1.3/m3) and most densities were less 3 than 0.5/m . They were present at all stations in September 1981,. May, and September 1982 and occurred at some of the stations on every cruise. Densities were typically low in the rivers and upper bay since most species were high salinity forms. Aegathoa was collected at salinities as low as 6 ppt. Mud Bay stations TA and TC were consistently the locations of highest abundance for isopods. In the intensive series, isopods were consistently most abundant at MN where all species occurred. A density of 1.3/mr3 at MN. in May was the highest for all stations on all cruises. US densities were clearly the lowest of the 3 stations. Insufficient numbers were collected to determine variation between 3, 6, and 9 minute tows at any location. At NMF and SJ, isopods also usually occurred at densities less than 1/m3. They were collected throughout the year, but were most abundant during the warmest months. Isopods were most common in the lower bay during the 1980-81 study. Densities ranged from 10/m3 at MN in September to less than 1/m3 at other locations. Peak densities were during the warmest months. Densities ranged from 0.1 - 11.2/m3 during the 5 hour special series study at MN (Table 6-3). Such a fluctuation indicates the high tidal variability associated with isopods. Bottom densities 6-18 were higher than those near the surface (Table 6-3), but isopods made up a higher proportion of the surface catch, especially during moderate and strong current conditions (Table 6-4). Surface catches were dominated by Aegathoa. Densities of isopods increased with increasing current velocities (Table 6-3). Although they were present at all locations during the study, isopods were not abundant enough in sled collections to consider them important components of the system. Sled determined densities are certainly underestimates of actual abundance for benthic forms and for Aegathoa which is a good swimmer capable of avoiding the net. D. CUMACEANS This last group of pericarid crustaceans includes Leucon americanus, Cyclaspis varians, Oxyurostylis smithi, and at least two unidentified species. As a group, cumaceans occurred in only 20% of the collections. Maximum density for the study was less than 0.5/m3. Cumaceans were present in lower and middle bay collections on most cruises during the warm months. Middle bay stations TC, MB, and EP were the locations of maximum abundance throughout the year. None occurred in the rivers during most of the year; however, in September 1982 when bottom salinities were 10 to 15 ppt, significant numbers were collected at PD, SR, and WR. No cumaceans were taken at any stations in JaTuary or in July when salinities were low. 6-19 Among the intensive series stations, MN was consistently highest in cumacean densities. A maximum density of 0.8/m3 was observed in May and some cumaceans were taken at MN on every cruise. MS densities were comparable, but few were collected at US. Numbers were too low to test differences between 3, 6, and 9 minute tows at any station. Low densities characterized the six Winyah Bay stations during the 1980-81 study. Peak densities were 4/m3 at MB, but lower bay collections were consistently highest. NMF and SJ densities 3 were usually less than 1/m3. Cumaceans were the least important of the pericarid crustaceans in the system, but since these organisms spend most of their lives buried in the sediment, they may be more abundant than sled catches would indicate. E. DECAPOD SHRIMPS: ADULTS At least 15 species of small adult decapod shrimps were collected with the sled. All 3 species of Penaeus and Trachypenaeus constrictus were collected as sub-adults and adults. Young Sicyonia spp. occurred in some summer collections at MN. Adult Palaemonetes vulgaris and P. pugio were widely distributed. These larger shrimps were considered incidental catches and not enumerated. Smaller (< 15 mm) adult shrimp such as Periclimenes americanus, Latreutes parvulus, Lysmata wurdemmani, Tozeuma carolinense, Neopontonides beaufortensis, and Ogyrides spp. were occasionally 6-20 collected in low numbers in the lower bay. These species were enumerated during sample processing, but are not discussed here. Snapping shrimps such as Alpheus spp. and the mud shrimps Upogebia affinis and Callianassa spp. were rarely encountered. Larval and small adult stomatopods or mantis shrimps (Squilla empusa) were also collected. None of these species is considered individually in this report, but the larvae of all decapod shrimps are considered as a group in another section. Two small adult sergestid shrimps were studied in more detail. Acetes americanus is a coastal species which only occurred in the lower bay during the warm months. Among the extensive series stations, densities were always highest at SB. Maximum densities 3 (0.3/m ) were in September 1982. None were collected at any station in January and March. This pattern is similar to that determined in the 1980-81 study, but summer densities were higher (maximum 3 3 31/mr at MN) during that year. SJ densities reached 5/m3 in August 1980 and NMF densities peaked at 1/m3 at that time. Lucifer faxoni had a similar pattern of spatial and temporal distribution. Both sergestid species were often taken in the same collections.Lucifer was somewhat more abundant than Acetes 3 with densities reaching 3.3/m3 at MB in March. Highest densities in Winyah Bay were at SB in September 1981 and November. None occurred at any station during January and July when salinities were lowest. With the exception of a few individuals in saline bottom waters at SR, none occurred in the rivers. 6-21 Lucifer was present at MN during the September 1982 special series sampling in sufficient numbers to comment on its short term distribution. Densities ranged from 0.7 to 7.8/rn3 over the 5 hour period (Table 6-3). There was no difference between bottom5 and surface densities and abundance in the samples was not closely related to the stage of the tide (Table 6-3). Lucifer accounted for a larger portion of the surface catch at moderate and strong velocities (Table 6-4).3 Both sergestid shrimps are high salinity warm water species5 which have a very limited distribution within the estuary. They may be considered indicator species for higher salinity water masses within Winyah Bay. F. DECAPOD SHRIMPS: LARVAE The taxonomic composition of the larval shrimp catch was not precisely determined because of the high diversity of species represented during the warm months. Most decapod shrimp'species pass through 4-7 stages of development before they become small adults and most of these larval stages are difficult to identify to the species level. There is little doubt that the vast majority of early stage shrimp larvae in the upper bay were Palaemonetes spp. since grass shrimp are one of the few shrimps capable of reproducing in low salinity areas. Grass shrimp larvae were also collected at the most seaward stations along with other larvae belonging to spec'es listed as small adults in the previous section. 6-22 The patterns described in this section are for total shrimp larvae. A distinct seasonal trend with maximum densities occurring during the warmest months is consistent with previous studies in other temperate estuaries. In Winyah Bay, highest densities were in May and July (2.4/m3) (Table 6-1). March and September 3 (1981 and 1982) values were on the order of 1/m . Densities less than 0.1/m3 were typical of the coldest months. Shrimp larvae were not a significant part of the epibenthic community from March to November, but they comprised 25% of the catch in July (Fig. 6-1). Among the 14 stations sampled, SR had the highest mean 3 density (2.9/m ) (Table 6-2). Lowest densities were at PR and TA (0.5/mr3) and most other stations had mean values around 3 3 1/m . During 1980-81, maximum densities (3/m3) were found at WR and MN. Summer peak densities at SJ and NMF were from 4 to 6/m3. Shrimp larvae comprised the largest portion of the catch (30%) at WR, although this group was also important at SR, PS, TC, and SB (Fig 6-2). They accounted for at least 5% of all organisms collected at every station. The highest density determined in the study was 15/m3 at SR in July (Appendix V. C.). No shrimp larvae were taken in the rivers or upper bay in November, January, or March. TA was the only station with some shrimp larvae on the January cruise. Densities increased at all stations from March to May and decreased after September. Gravid adult shrimp were never collected during the 6-23 coldest months. Densities at intensive series stations US and MN were similar (1.5/m3) and somewhat higher than those at MS (Fig 6-5). There. did not appear to be significant differences in densities determined with 3, 6, and 9 minute tows but further statistical tests will be conducted to establish the degree of patchiness. The seasonal pattern for the intensive series was identical to that determined in the extensive series with one notable exception. Some shrimp larvae occurred in every tow at US in March. July US densities were among the highest in the study (Appendix VI. C.) Shrimp larvae densities ranged from 1.4 to 10.4 over the 5 hour study at MN in September 1982 (Table 6-3). There was no significant change in density as a function of tidal velocity. Even though larvae were more abundant in bottom than surface collections (Table 6-3), they accounted for a larger percentage of the surface catch at all stages of the tide. Shrimp larvae were the second most important group at the surface during slack and moderate stages of the tide. G. DECAPOD SHRIMPS: POSTLARVAL PENAEIDS Late larval stages of the penaeid shrimps are readily recognized in epibenthic sled collections and because of the commercial importance of this group of shrimps, they were enumerated in the ana.-?ses. The spatial and seasonal patterns of distribution described here are for larval shrimps belonging to the genus Penaeus (or 6-24 Fig. 6-5. Mean densities (+1 S.E.) for 3, 6, 9 minute and all sled collections at 3 intensive series stations in Winyah Bay. Values are means of all 7 cruises. 2.5_ SHRIMP LARVAE 1.5 m4 1 1.0 _ 0.5- t JI I I I I ! I I I 3 6 9 all 3 6 9 all 3 6 9 all UPPER MIDDLE LOWER 2.2 ' 20'FISH LARVAE ' 2.0 � 0.9 2.0 ' 1.8 i 1.6 - 4~~~~~~~~~~~~~~~~~~~~~~~~~~I e 1.4 - d 1.4 1.2 - 1.0 - 0.8 - 0.6 - 0.4 - 0.2 - i I i I i I .. , I 3 6 9 all 3 6 9 all 3 6 9 all UPPER MIDDLE LOWER 6-25 Trachypeneaus). No attempt was made to separate the individuals to species. Although there is no doubt that huge numbers of these larvae migrate from the ocean to estuarine nursery areas in Winyah Bay, they grow very rapidly and are probably only susceptable to capture by the sleds for days or weeks. For this reason and because of the likelihood that postlarval penaeids reside in habitats other than those routinely sampled with the sleds, it is not surprising that densities in the collections were so low. Nevertheless, information given for the general seasonal and spatial distribution of these larvae represents the only data of its kind. Extensive series station densities were usually less than 3 0.5/m . Highest densities were in May and none were collected in January or March (Table 6-1). Among all stations, TA had the highest mean density (0.8/mn3) (Table 6-2). Most stations had mean densities of less than 0.1/m3. None were collected at PR on any cruise. The highest density of postlarval penaeids determined in the study was 5.2/m3 at TA in May (Appendix V. D.). None had been collected at any station during the two previous cruises (January and March) and penaeid larvae were only collected at two other stations on the May cruise. They were more common in the lower and middle bay in July and occurred at all stations except PR in September 1982. However, densities were always less than 0.3/m3 whenever they were present. 6-26 No penaeid postlarvae were collected at the intensive stations from September through March (Appendix VI. D.). Some occurred in the US in May, the US and MS in July, and the LS and MS in September 1982. Generally, densities were less than 0.1/m3. Too few were captured at the ship channel stations to compare differences between the 3, 6, and 9 minute tows. None were collected during the special series at MN. H. DECAPOD CRABS: MEGALOPAE At least 7 species of anomuran and 14 species of brachyuran crabs were collected during the sled study in Winyah Bay. As was the case with the shrimps, the occurrence of individuals larger than about 15 mm was considered incidental. Hermit crabs (Pagurus spp. and Clibanarius vittatus) were occasionally present in collections, but the sled did not effectively sample these common forms. Other anomurans including Euceramus, Porcellana, Emerita, and Hypoconcha were also incidentals. Among the brachyurans, Callinectes, Portunus, Ovalipes, Calappa, Libinia, and Cancer were sometimes represented by juveniles and small adults. Menippe, Neopanope, Rhithropanopeus, and Pinnixa were also collected, usually in association with bottom debris or shell. Almost all of these species were most commonly encountered in the lower bay. Fiddler crabs of the genus Uca were never taken as adults in the sled, but megalopa stage larvae of this group were common in summer collections. The analysis of the distribution of megalopae 6-27 that follows is for total crab megalopae Crab megalopae densities were uniformally low throughout the year. None occurred on the January cruise, and the highest overall density was only 0.2/mr3 in September 1981 (Table 6-1). Megalopae never accounted for more than 2% of the total catch for any cruise (Fig. 6-1). Among the stations, MN had the highest overall density of 1.3/m3. All other stations had mean values of 0.3/m3 or less (Table 6-2). Megalopae did not account for more than 5% of the catch at any station except SB (8%) (Fig 6-2). Megalopae were present at most stations on all cruises except January, when none occurred anywhere, and March (Appendix V. E.). The highest density was at SB in May (1.4/mr3), but most values 3 were less than 0.5/m . Densities were consistently low at PR, TA, and PS even during the warmest months when magalopae were most abundant. Although the same seasonal pattern was found during the 1980-81 studies at NMF, SJ, and 6 Winyah Bay stations, megalopae were less abundant during 1981-82. Maximum densities in the previous study were greater than 50/mr3 (MB, June). Since the megalopa is a relatively short-lived developmental stage, sampling intervals on the order of weeks or months are too long to generate a good understanding of temporal patterns of abundance. Additional short term studies at locations in the lower bay are necessary to elucidate these patterns. 6-28 The seasonal pattern for crab megalopae in intensive series collections was identical to that in the extensive series. None were taken anywhere on the January cruise and few were collected in the US on most cruises (Appendix VI. E.). Low densities made it difficult to determine whether their distribution on the bottom was patchy. Densities were also low on the special series cruise at MN in September 1982. The range was from 0.1 to 1.2/m3 (Table 6- 3). Bottom densities were higher than those at the surface (Table 6-3), but megalopae accounted for 21% of the surface catch at slack tide (Table 6-4). The proportion of the surface catch was negligable at moderate and strong velocities. All megalopae examined in these samples were Uca spp. I. FISHES: EGGS The identification of fish eggs to even the family level is a very difficult and tedious task. It was beyond the scope of this study to process samples on this level, so the discussion below is restricted to total fish eggs. Interpretation of the patterns is complex because: (1) fish eggs exist on time scales of hours to days, (2) many species produce eggs that are too small to be retained in 365 um nets, and (3) some species produce eggs that are attached to the bottom and others have various degrees of buoyancy. There is no doubt that the sled collects only a small portion of the available eggs in that section of the water 6-29 column which is least likely to have high densities of eggs. The only cruise on which fish eggs were present in high densi- ties was May when values were 5.9/m3 (Table 6-1). None were taken in January and September 1982; other months had overall densities on the order of 0.1/m3. TA had the highest overall densities (5.0/m3). The next highest values were at MS (2.6/m3). Only small numbers were collected in the rivers, but some were present at all stations (Table 6-2). No eggs were collected at any station in January or September 1982 and the only ones collected in September 1981, November, and March were in the lower estuary (Appendix V. F.). May was the only cruise on which fish eggs occurred at every station. The highest densities of the study were 35/m3 at TA and 14/m3 at BI in May. A similar low density pattern was found at NMF, SJ, and the Winyah Bay stations in 1980-81. A similar seasonal pattern was observed during the intensive series. Among these stations, densities were also highest in the middle bay in May. Densities were too low to determine differences between 3, 6, and 9 minute tows (Appendix VI. F.). Similarly, num- bers of fish eggs in the special series were too low to comment on vertical distribution or the effect of tide stage. J. FISHES: LARVAE Most of the problems associated with the identification and 6-30 quantification of fish eggs in estuarine waters also apply to fish larvae. Certainly more than 180 species of fishes are repre- sented by eggs and larvae (or postlarvae) in South Carolina estuaries. Early yolk-sac stages cannot be easily identified beyond the family level; however, older larvae were distinguished to lower taxonomic levels during sample processing. Following verification of the identification and the measurement of all individuals, further information on how various species utilize Winyah Bay will be available. Preliminary information based on the analyses of sled collected larvae at NMF and SJ Creeks is available in Chapter 7 of the first report (Allen et al., 1982). A list of fish larvae identified from Winyah Bay sled collections in 1981-82 is presented in Table 6-5. In this section, spatial and temporal distributions for total fish larvae are described. Fish larvae were most abundant on the May cruise (2.7/m3 (Table 6-1). The mean density for March was 1.3/m3, and values for all other months were 0.2/m3 or less. Larvae were important constituents of the catch in March and May (15%), but they were less abundant on all other cruises (Fig. 6-1). Among all stations, MB had the highest densities (2.5/m3). Values at TA, PS, and MN were less than 1/m3, and all other stations had much lower mean densities (Table 6-2). Fish larvae accounted for more than 10% of the catch at TA, PS, MB,. and SB in the middle and lower bay (Fig. 6-2). 6-31 Table 6-5. List of species of fishes represented by larvae or postlarvae in epibenthic sled collections in Winyah Bay Estuary. FAMILY GENUS-SPECIES COMMON NAME Elopidae Elops saurus ladyfish Anguillidae Anguilla rostrata American eel Ophichthidae Myrophis punctatus speckled worm eel Clupeidae Alosa spp. blueback herring and/or American shad Brevoortia tyrannus Atlantic menhaden Dorosoma spp. gizzard shad and/ or threadfin shad Engraulidae Anchoa mitchilli bay anchovy Anchoa hepsetus striped anchovy Synodontidae Synodus foetens inshore lizardfish Ariidae Arius felis hardhead (juveniles) Ictaluridae Ictalurus spp. brown bullhead and/ or channel catfish Batrachoididae Opsanus tau oyster toadfish (juveniles) Gobiesocidae Gobiesox strumosus skilletfish Gadidae Urophycis spp. southern hake and/ or spotted hake Atherinidae Menidia menidia Atlantic silverside Syngnathidae Syngnathus spp. northern pipefish and/or chain pipefish (juveniles) Percichthyidae Morone spp. striped bass and/ or white perch Serranidae Centropristis striata black sea bass Centropristis philadelphica rock sea bass Carangidae Caranx spp. crevalle jack and/ or horseeye jack Chloroscombros chrysurus Atlantic bumper 6-32 I Table 6-5 Cant. 5 ~~FAMILY GENUS-SPECIES CO4MMON NAME Centrarchidae Lepomis spp. redear and/or '3 ~~~~~~~~~~~~~~~~~~redbreast sunfish Lutjani~dae Lutjanus griseus gray snapper Gerreidae Eucinostomus spp. spotf in mojarra and/or silver jenny Pomada syidae Orthapristis chrysoptera pigfish I ~ ~Sparidae Lagodon rhomboides; pinfish Sciaenidae Bairdiella chrysura silver perch Cynoscion regalis weakfish Leiostomus xanthurus spot Menticirrhus spp. northern kingfish S ~ ~~~~~~~~~~~~~~~~~and/or southern kingfish Micropogonias undulatus Atlantic croaker Sciaenops ocellata red drum 5 ~~~~~~~~~~Stellifer lanceolatus star drum Ephippidae Chaetodipterus faber Atlantic spadefish (juveniles) Mugilidae ?4 icephalus striped mullet (juveniles) Blenniidae Hypsoblennius hentzi feather blenny Gobiidae Gobiosoma spp. naked goby and/ 3 ~~~~~~~~~~~~~~~~~~or seaboard goby Stromateidae Peprilus alepidotus harvestfish (juveniles) Peprilus triacanthus butterfish (juveniles) 5 ~~Triglidae Prionotus spp. bighead searobin and/or leopard searobin Bothidae Ancyclopsetta quadrocellata ocellated f launder 6-33 Table 6-5 Cont. FAMILY GENUS-SPECIES COMMON NAME Citharichthys spilopterus bay whiff Etropus crossotus fringed flounder Paralichthys lethostigma: southern flounder Paralichthys dentatus summer flounder Soleidae Trinectes maculatus hogchoker Cynoglossidae Symphurus plagiusa blackcheek tonguefish Balistidae Monacanthus hispidus planehead filefish (juveniles) 6-34 The highest density determined in the program was about 16/m3 at MB in May (Appendix V. G.). The only other major catches were at TA and PS in March and May. River densities were typically low. Densities were usually less than 1/m3, and none were collected anywhere in January. In general, highest numbers occurred in the middle bay in spring (Appendix V. G.). Densities at NMF and SJ Creeks were higher than most Winyah Bay Stations. Winter values of about 3/m3 and summer densities from 6 to 12/m3 in these creeks may indicate that such habitats are more important nursery areas than open waterways. During 1980-81, Winyah Bay densities were usually about 1/m3. Intensive series patterns of abundance were similar to the extensive series patterns in that US densities were lowest. Densities at MS and MN were comparable to extensive series station values. Generally, highest densities were in the spring (Appendix VI. G.). Some differences in the densities determined in 3, 6, and 9 minute tows may indicate the extent to which larvae occur in patches on the bottom (Fig. 6-5). On the special series MN cruise, fish larvae densities ranged from 0.1 to 6.9 (Table 6-3). The range in densities during a 5 hour study at one location was greater than the differences between adjacent stations or cruises in the'extensive cruises. Such variability is common among these motile organisms. During the special series, fish larvae densities decreased as velocity increased (Table 6-3). Surface densities were greater than bottom 6-35 densities (Table 6-3) and larvae accounted for a larger percentage of the surface catch during slack and moderate current conditions (Table 6-4). Fish larvae were the most important (45%) group in surface collections at slack tide; they became less important at the surface as current velocities increased (Table 6-4). K. CHAETOGNATHS Chaetognaths or arrow worms are very abundant in Winyah Bay, especially in the lower bay during the warm months. During the 1980-81 study of motile epibenthos, chaetognaths dominated 7 of the 9 cruises at MN. Densities of these elongate (< 10 mm) 3I zooplankton predators were often on the order of 100/mi At least 3 species of the genus Sagitta were identified in lower bay collections. A similar seasonal pattern was found at NMF and SJ during 1980-81, and densities were equivalent to those in the lower bay at the same time. Chaetognaths are high salinity coastal species which are moved toward the upper bay with the salt wedge and, thus, may serve as indicators of salt water penetration and water mass residence time in the upper bay. Since sample processing time was more than doubled when chaetognaths were present, it was difficult to justify counting all individuals. Problems with retention of small individuals in 365 gm nets, their wide vertical distribution within the water column, and the apparent insignificance of chaetognaths in the diets of estuarine fishes all contributed to the decision not 6-36 to count chaetognaths in either the sled or zooplankton collections during the 1981-82 extensive or intensive series. Chaetognaths were counted in the special series collections 3 at MN. Densities ranged from 1 to 34/m . Bottom densities were greater than surface densities and they increased with increasing current velocity (Table 6-3). They were the most important organisms in the collections at all stages of the tide, but accounted for a larger proportion at the bottom than the surface (Table 6-4). L. MEDUSAE AND CTENOPHORES Medusae representing many hydrozoan families (especially F. Bougainivilliidae) were collected in most samples during most of the year. Larger jellyfish such as Stomolophus meleagris, Chrysaora quinquecirrha, and Rhopilema verrilli were incidentals in the sleds. Ctenophores commonly collected were Mnemiopsis leidyi and Beroe ovata. Sometimes small (< 15 mm) jellyfish were so dense that sample volumes were more than one liter. The first attempt to conduct the special series in September 1982 at MS was cancelled after 2 hours because medusae fouled the nets. Medusae were not enumerated in any of the samples for the same reasons that chaetognaths were not counted; however, a distinct pattern was observed. Small medusae were most abundant in the middle bay in summer and fall. Whereas chaetognaths were major zooplankton predators near the ocean, medusa dominated near the bottom further up the bay especially -J the channel. Few medusaa were found in the river or at the lower bay stations near flood tide. Other 6-37 sampling gear and procedures must be used to determine more specific patterns of medusae and ctenophore distribution within Winyah Bay. There is no doubt that medusae play a major role in the estuarine food web and may be a major factor influencing zooplankton abundance and community structure. When medusae were abundant, densities of all motile epibenthos, especially mysids, were near zero. M. TOTAL ORGANISMS In this section trends for total epibenthic organisms are discussed. The category includes mysids, amphipods, isopods, cumaceans, decapod shrimp larvae, postlarval penaeids, Acetes, Lucifer, crab megalopae, fish eggs and fish larvae. None of the incidental forms (e.g. chaetognaths, medusae, crab zoeae orcopepods) was considered in this analysis even though such forms often totally dominated the sled collections. Overall densities for total organisms were on the order of 5 to 10/m3 during September 1981, November, January, March, add July and reached their highest levels in May (19/m3) and September 1982 (25/m3) ( Fig 6-6). An abrupt increase in density occurred in May after relatively low densities persisted through the winter. The lower density on the July cruise was probably related to the major freshwater runoff at this time. Low upper and middle bay salinities in July are thought to have displaced the high salinity forms,which dominate the summer community,toward the ocean. During 6-38 b - _ - - - - - -- - - - - � Fig. 6-6. Mean densities (�1 S.E.) of total epibenthic organisms on all 7 extensive series cruises in Winyah Bay in 1981-82. Each value is the mean for all 11 stations on that cruise. 26 4 25.3 � 9.2 24 - TOTAL EPIBENTHOS 22 - 20 - 18 - 16 - A o 14 12 - 10 - It 8 - 6 1 4- SEP NOV JAN MAR MAY JUL SEP SEP NOV JAN MAR MAY JUL SEP the 1980-81 study of 6 stations, total organism densities ranged from 4 to 25/m3 with a peak of 55/m3 in June (Allen et al., 1982). The seasonal pattern and overall abundance at NMF and SJ Creeks was comparable to the middle bay stations. Of the 14 stations sampled in 1981-82, PD had the highest density of total organisms (31/m3) (Table 6-7). This was almost entirely due to the occurrence of high densities of amphipods during summer and fall. At most stations mean densities were 10 to 100 organisms/m3 (Fig. 6-6). Lowest values (about 5/m3) were found at PR, WR, US, TC, and SB. Highest variability between cruises was at the river stations, where salinity fluctuations between cruises were highest. Total organism density tended to be highest in the middle bay, especially at TA, MS, and EP (Fig. 6-7). Mud Bay stations PS and TC were more comparable to lower bay stations SB and MN. PR had the lowest mean density, but WR and US were also low. The density at SR was significantly higher than at the other river stations with the exception of PD. The highest density of totaJ organisms collected in the study was 147/m3 at PD in September 1982 (Appendix V. H.). The second highest density was at TA in May. Most collections had 2 to 15 organisms/m3, but no motile epibenthic organisms occurred at PR in November or WR in January. Generally, total organism densities throughout the bay were lowest in winter and when salinities were lowest (Appendix '. H.). 6-40 Fig. 6-7. Mean densities (+1 S.E.) of total epibenthic organisms at all 11 extensive series stations in Winyah Bay in 1981-82. Values are means.of all collections taken at that location on the seven cruises. 32.5-- ~30.~0-~ ~~4 30.6 + 14.1 30oo0- 3 06- t 14. 1TOTAL EPIBENTHOS 27.5 - 25.0 22.5 - 20.0- .,-4 o 17.5 - 4 15.0 I 12.5 - 10.0-- 7.5 -- 't 2.5 PR SR PD WR BI TA PS TC EP ' MB SB The range in densities between intensive series cruises was from 5 to 15/m3 and the seasonal pattern of distribution was consistent with the summary based on the extensive series (Fig, 6-3). US densities were generally lower than MS and MN densities, with the exception of the May cruise on which very high densities of mysids were caught in a few of the US tows (Appendix VI. H.). Total organism densities on the special series cruise at MN in September 1982 ranged from 6 to 66/m3 over the 5 hour period CTable 6-6). Higher densities occurred on the bottom than surface especially during strong current conditions (Table 6-3 and 6-5). There was a trend toward increasing abundance with increasing current velocity (Table 6-3). N. SAMPLING CONSIDERATIONS One of the purposes of the special series cruise was to examine the differences in the performance of various sampling gear. A comparison of total organisms in closing nets deployed at the surface and bottom showed significantly more animals occurred at the bottom during slack and strong current conditions; more were in surface tows during moderate currents(Table 6-4). Un- fortunatly, values at both levels at slack and moderate tides may be misleading because such low volumes of water were filtered. There were no significant differences in the size of the catch between the 0 to 30 cm level and the 30 to 60 cm level sled nets at any stage of the tide (Table 6-6). Single level sled values were very similar to those in both levels of the double sleds. 6-42 MM- mm"m m -Mm mm mm M - Table 6-6. Comparison of densities of total organisms collected in different gear types at slack, moderate, and strong current conditions. Values are mean number per cubic meter plus or minus one standard error. Slack Moderate Strong All Surface closing net 14.5 � 3.6 49.5 � 19.0 17.2 � 1.4 26.4 � 9.2 Bottom closing net 57.1 � 23.1 23.3 � 5.5 57.6 � 8.0 .45.9 � 10.5 O! Upper level sled 12.7 � 1.4 28.9 � 2.8 66.4 � 6.2 33.8 � 6.9 Lower level sled 12.1 � 1.3 36.6 � 4.4 56.0 � 5.0 33.3 � 6.2 Single level sled 7.2 � 0.6 47.6 � 2.3 52.2 � 1.9 34.9 + 7.5 Densities of total organisms increased in all sleds as current velocities increased (Table 6-6). This trend was also evident when all gear were considered together (Table 6-7).1 By far the highest densities (95/rn3) were collected when3 nets were towed against a strong tide; however, the mean density for tows in the direction of the strong tide (54/m ) was also high (Table 6-7). All of this evidence indicates that sleds are most effective in collecting organisms during peak tides, presumablyI when many swimming forms remain near the sediment - water interface where current velocities are lowest. Changes in the vertical distribution of organisms susceptible to capture in 365 amn nets3 and/or changes in the effectiveness of the sampling device in capturing the organisms are two major problems which complicate1 the interpretation of field survey data. Since there was no way to collect samples at the same stage of the tide at all stationsI on each cruise, care had to be taken to sample the stations in the same sequence on each cruise. Starting time, time on station, atid travel time between stations were consistent between cruises.3 On extensive cruises, lower bay stations were sampled at the beginning of ebb tide. Middle bay stations were sampled around peak tides,3 and upper bay stations were sampled near low tide. On intensive series cruises, lower and upper bay stations were sampled at moderateI ebbing velocities and middle bay samples were taken near peak3 velocities. Mud Bay and PR velocities were always low. Further analyses will be conducted using all available data to determine the extent to which stage of tide may have influenced patterns of abundance.3 6-44 ~~~~~~~~~~~~~~~~~~~mm MMMMMM"AMmir mm - - - -- -- -- - - - Table 6-7. Comparison of densities of total organisms collected at slack, moderate, and strong tidal velocities. Mean values (�+ S.E.) are given for (1) all gear towed in the direction the tide was flowing, (2) all gear towed against the tide, and (3) all gear deployed from an anchored boat. Towed With Tide Towed Against Tide Stationary All Methods Slack 5.7 �+ 0.9 17.2 �+ 5.2 25.4 + 8.7 18.3 �+ 5.0 al Moderate 28.9 + 6.3 26.9 + 1.1 46.9 + 7.9 33.7 + 5.4 Strong 53.5 + 2.3 94.5 + 9.3 31.3 + 6.1 53.0 + 7.6 0. SUMMARY Motile epibenthic crustaceans and fishes constitute an essential link in the estuarine food web. Most of these small animals assimilate plant material, algae, and microorganisms and make this energy avail- able to higher trophic levels. Other species are represented in the community by developmental stages of forms which grow and eventually feed on smaller epibenthic crustaceans. Mysids, amphipods, and small decapods are major sources of food for most commercially and recrea- tionally important fishes in Winyah Bay. Petroleum pollutants threaten the motile epibenthos through several mechanisms, but the most significant potential harminvolves the accumulation of hydrocarbons in fine grained sediments. Since these organisms live near the bottom, they are particularly suscep- tible to the ingestion of polluted particles. Lethal and sublethal effects on respiration, growth, feeding, and reproduction are known for common epibenthic forms. Low concentrations of toxic petrochem- icals associated with the effluent of a refinery are likely to have adverse long term effects on these organisms. Due to their critical ecological role, destruction of motile epibenthic forms will have severe repercussions for the entire estuary. 6-46 I ~~~~~CHAPTER 7. ECOLOGY OF WINYAH BAY AND POTENTIAL IMPACTS OF CHRONIC AND ACUTE OIL SPILLAGE It is estimated that tens of thousands of scientific papers I ~~~describing the effects of petroleum on the marine environment have been published in the past twenty years (Gunkel and Gassmann, 1980). Fortunately, it is not necessary to examine the entire literature 3 ~~~base available to achieve an understanding of the impacts of petro- leum on temperate marine environments. Numerous literature reviews 3 ~~~by respected authorities in the field have been published recently which summarize this voluminous literature and attempt to integrate information which may often appear to be contradictory and confusing (NAS, 1975; Clark, 1982; Olsen et al., 1982). Also, a review of I ~~~literature more pertinent to the habitats and species assemblages 3 ~~~present within Winyah Bay has been previously prepared (Allen et al., 1982). 3 ~~~~Since further extensive review of the literature would be ex- tremely time consuming and repetitive, it is the intent of the authors 3 ~~~to only present examples from the most recent literature which add to our understanding of oil impacts in the marine environment. Following I ~~~a survey of the most recent literature, we will attempt to integrate 3 ~~~probable impacts with what is now known about the ecology of Winyah Bay. Emphasis will be placed upon the effects of oil on primary 3 ~~~producers, zooplankton, and epibenthic organisms (including early life history stages of fishes, crabs, and shrimps) since this was t'-e 3 ~~~focus of phases II and III of the study. 3 ~~~~~~~~~~~~7-I A proposal to construct and operate a crude oil refinery on the Sampit River in upper Winyah Bay has generated considerable interest3 in the potential impacts of the industry on the Winyah Bay Estuary. In addition to the three phase study reported in Allen et al. (1982)3 and the present document, the Coastal Energy Impact Program (NOAA) supported three other investigations of oil pollution in Winyah Bay. Our studies describe physical, chemical, and biological character- istics of the estuary and assess potential impacts of petroleum, especially on zooplankton and early life stages of crustaceans and5 fishes which inhabit the system. Thebeau et al. (1982) developed an Environmental Sensitivity Index which classifies each coastal habitat type according to its vulnerability to spilled oil. They found that more than 80% of the shoreline of Winyah Bay falls within the most5 sensitive categories. May (1982) developed an oil spill trajectory model for Winyah Bay. Difficulties in predicting the fate of spilledI oil and deploying effective containment and clean-up equipment inU a large and physically dynamic estuary such as Winyah Bay are f or- midable. Bidleman and Svastits (1983) conducted baseline measure-3 ments of petroleum hydrocarbons in water samples from locations within Winyah Bay and found present levels were low.3 7-21 3 ~~~~~FATES AND IMPACTS OF OIL IN THE MARINE ENVIRONMENT; A SURVEY OF RECENT LITERATURE It is estimated that half of the petroleum discharged by the 3 ~~~United States into the marine environment enters estuaries from coastal metropolitan areas and rivers (NAS, 1975). Concentrations U ~~~of petroleum hydrocarbons in the water column typically approach 3 ~~~0.1 ppm near these metropolitan areas. Although water column "concentrations decline rapidly with distance from the source, 5 ~~~surface sediment concentrations of 500 ppm or greater appear to be present over large portions of urbanized estuaries" (Olsen et al., 3 ~~~1982). Recent research suggests that "major environmental impacts may be expected when water column concentrations are sustained at 3 ~~~0.1 ppm and more and when surface sediment concentrations attain 3 ~~~500 ppm" (Olsen et al., 1982). It is impossible to precisely determine the fate of oil from 5 ~~~specific discharges (Wheeler, 1978) because of highly variable environmental conditions; however, it is now known that all but 3 ~~~the most volatile fractions are incorporated into the bottom sedi- ments (Olsen et al., 1982). Most of the serious long term effects 3 ~~~associated with oil discharges are reported for low energy environ- ments (lagoons, estuaries, and marshes) where oil tends to persist 3 ~~~for long periods (Vandermeulen, 1982). In general, substantial 3 ~~~restoration to pre-spill conditions in acutely polluted areas occurs within two years (Clark, 1982). However, subtle changes in sensitive areas may persist for decades (Southward and Southward, 3 ~~~~~~~~~~~7-3 1979; Sanders et al., 1980; Vandermeulen, 1982). 1 Effects of chronic discharges are often difficult to determine 3 since these subtle changes may be masked by natural changes (Lewis, 1982). Generally, intertidal and subtidal benthic communities respond 3 most dramatically. Temporal changes after an acute spill are similar to spatial changes observed around chronic discharges. Such effects 3 are generally seen as "a simplification of the ecosystem with domi- nance of a few species" (Southward, 1982). 1 Three approaches have been used to determine the effects of oil 3 on marine ecosystems. The first approach employs bioassays which determine the minimum concentrations of petroleum or its constituents 3 necessary to kill the test organisms. Table I summarizes results of some 96 hour bioassays which have been conducted on a variety of marine organisms (from Olsen et al., 1982). Although the lethal concentration is influenced by numerous factors (including the type of oil, the manner in which the oil is presented, and the sensitivity of the species) bioassays provide important information about the relative toxicity of hydrocarbons to different species and life 3 stages in a community (Olsen et al., 1982). Generally, juveniles are more sensitive than adults and larval crustaceans appear to be 3 among the most sensitive groups of organisms to hydrocarbons (Rice et al., 1977 ). I In the second approach, field observations are used to report the actual effects of chronic and acute oil pollution. Hundreds of I scientific papers describe significa-t reductions in zooplankton, 3 7-4 1 Table 7-1. Lethal Concentrations of Crude and No. 2 Fuel Oil Determined Through 96-Hour Bioassays in Which Hydrocarbon Concentrations Were Measured Directly (Adapted from Rice et al., 1977a) Crude Oils No. 2 Fuel Oil Source (ppm) (ppm) 6 Species Shrimp and Crab 0.9-1.8 - Brodersen et al., 1977 Stage I Larvae 4 Shrimp Species - 1-6.6 Neff et al., 1976 6 Crustacean Species 0.6-4.2 0.5-1.7 Rice et al., 1977b 4 Limpet and Chiton Species 3.6-9.6 0.4-5.6 Rice et al., 1977b 3 Fish Species 5.5-19.8 3.9-6.3 Anderson et al., 1975 4 Fish Species 1.2-2.9 0.8-2.1 Rice et al., 1977b 3 Polychaetes 9.5-12.5 2.3-2.7 Rossi et al., 1976 Polychaete 12.5-19.8 2-8.4 Rossi and Anderson, 1976 shellfish, fish, bird, and benthic populations following an oil spill.I Much of this literature was reviewed previously (Allen et al., 1982) and will not be repeated here. Chronic oil pollution in rivers can also result in significant declines in commercial catches of fishes5 and crustaceans in adjacent bays (Spears, 1971). Medium and long term changes to fisheries stocks may be much more significant than3 any immediate effects which are reported (Cnexo, 1981).* The newest approach to studying oil pollution in the marine environment entails the use of microcosms which are built to mimic3 the marine ecosystem. A recent series of experiments which inte- grated pelagic and benthic ecosystems was conducted by researchers3 at the University of Rhode island (Olsen et al., 1982). Water accomodated No. 2 fuel oil was added to three microcosms and a con-3 centration of 0.2 ppm. was maintained throughout the experiment (February 1977 through October 1977). Effects were compared toI three un-oiled control microcosms. A second set of experiments5 was conducted from March 1978 through July 1979 in a manner similar to the first, but a lower concentration of 0.1 ppm was maintained.3 Recovery of the ecosystem was monitored for one year after oil additions ceased. Results of the experiments which measured effects3 on the experimental ecosystem are presented in Table 1I. The researchers' interpretation of the results is extracted verbatimI from published literature and is presented in summary form below (from Olsen et al., 1982): 1. General conclusions:3 "The chronic-addition experiments led to several major 7-61 Table 7-2. The Impacts of Sustained, Low Concentrations of No. 2 Fuel Oil (0.2 and 0.1 ppm) on Principal Trophic Components, Species, and Nutrients in MERL Microcosms Expressed as Percentages of Mean Oiled Compared to Mean Control Microcosms (from Oviatt et al., 1982) Recovery 0.2 ppm 0.1 ppm from 0.1 ppm A. Water Column C14 Productivity +179%b + 37% + 4% Chla +120%a + 67% + 25% NH3 - 77%b - 19% - 42% NO2 + NO3 - 71%b - 63% - 58% P04 - 14% - 40% - 63% SiO4 - 3% - 74%a - 63% Zooplankton Biomass - 43% - 23% - 9% Total Zooplankton - 78%b - 16% - 10% Acartia tonsa +633%c +463%a + 81% Acartia clausi - 69%a + 2% + 58% B. Macrofauna Total Macrofauna - 30%a - 42%b - 64% Mediomastus ambiseta - 35% - 55%b - 83% Nucula annulata - 37%a - 13% - 36% Ampelisca abdita -100% - 93%a - 98% Chaetozone sp. +221% +203% +276% C. Meiofauna Total Meiofauna - 38%b + 23% - 18% Nematodes - 46%b + 9% - 23% Harpacticoids - 57% - 35%a + 19% Foraminifera +257% +202%a - 14% Ostracods -100% - 94%b - 68%a Juvenile Bivalves - 3% - 90% - 37% Juvenile Polychaetes +223% + 18% +277% a. Statistically significant at the 90 percentile b. Statistically significant at the 95 percentile c. Acartia tonsa flourished in only one of the three oiled tanks; time- averaged numbers in each tank during oiling were 5242, 18, and 38. 7-7 conclusions. The first is that the key factors affecting the magnitude of the impact of oil on major components of the ecosystem are the generation times of species and the length of time organisms are in contact with the oil. Since the oil disappeared rapidly from the water column, populations of short-lived planktonic species sensitive to the low oil concentrations recovered days or weeks after oiling ceased. Approximately half the oil added to the water column became incorporated in surface sediments, and here it persisted and had severe, long-lasting effects on the longer-lived benthos." 2. Water column nutrients: "All principal nutrients were lower in the waters of oiled tanks than in controls. During the recovery experiment, for example, ammonia, nitrate, nitrite, phosphate, and silicate were all reduced by approximately 50 percent. This too is attributed to the radical decline in the benthic community, which therefore produced a slower rate of remineralization of nutrients to the water column." 3. Phytoplankton: "The phytoplankton flourished at sustained concentrations of both 0.1 ppm and 0.2 ppm and during the recovery experiment. Primary productivity, for example, increased by 179 percent at 0.2 ppm and by 37 percent at 0.1 ppm. Since many of the animals killed by the oil were herbivores, the reduction in their numbers is the most likely reason for increases in the 7-8 populations of phytoplankton. Experiments on the effects of similar concentrations of oil on isolated phytoplankton populations confirmed that the oil itself does not cause increases in plant biomass. Increases were also seen in the populations of benthic microflora in the oiled microcosms". 4. Macroalgae: "A visually obvious difference between the oiled and con- trol microcosms during both experiments was the virtual absence of the fouling community of primarily subtidal species of macroalgae that grew and had to be removed from the walls on the control tanks". 5. Benthic Fauna: "Once the concentration of hydrocarbons in the top one centimeter of sediments reached approximately 500 ppm benthic populations that were sampled every month during the experiment began to decline rapidly. The only excep- tion was on Chaetozone species that was tolerant of the oil and became twice as abundant in oiled tanks. The normally abundant populations of amphipods (primarily Ampelisca) and ostracods were particularly sensitive. The recovery experiment demonstrated that the benthic community was as severely depressed during the year after oiling had ceased as it was during the highest oil addition experiment". 7-9 6. Zooplankton: "Chronic additions that produced mean concentrations of 0.1 ppm and 0.2 ppm in both experiments caused reductions in the total biomass and numbers of zooplankton. At the higher concentration, zooplankton numbers declined by 78 percent and biomass by 43 percent. The drastic effect of the oil on the total zooplankton population was softened by the tolerance for oil at both concentrations shown by one species (Acartia tonsa). This large [copepod] crusta- cean took advantage of the abundant phytoplankton and was 633 percent more abundant in oiled tanks during the first oiling experiment and 463 percent more abundant in the second experiment, relative to the controls. After oiling ceased, the entire zooplankton population rebounded rapidly and was more abundant during the year-long recovery exper- iment in previously oiled tanks than in controls. This is attributed to the decreased grazing pressure of the benthic community". Ecological Consequences Of Oil Discharge Into Winyah Bay The physical complexity of an estuary such as Winyah Bay cannot be overemphasized in any discussion of the spatial and temporal dis- tributions of the organisms which inhabit it. At any location between the ocean entrance and the source of freshwater input, large changes 7-10 I ~~~in salinity, turbidity, current characteristics, nutrient concentra- 3 ~~~tions, and organism abundance occur over short intervals of time (minutes and hours). Variability over a single tidal cycle may be as large as that measured during an entire year. Because of the dynamic nature of estuaries, it is difficult to describe patterns 3 ~~~of distribution for most components; however, during the present study several general trends were observed and these patterns will I ~~~be described in this section of the report. 3 ~~~~The major characteristic used to distinguish water masses within an estuary is salinity. In the following discussion, three 3 ~~~salinity zones are identified and used to describe distributional patterns of chemical and biological components within Winyah Bay. 3 ~~~The upper bay is dominated by freshwater input from the rivers. The middle bay is the primary mixing zone, and the lower bay is I ~~~dominated by saltwater input from the ocean. During periods of low and moderate freshwater inflow, the salinity gradient from 0 to 35 ppt is gradual, but during major flooding periods most of Winyah 5 ~~~Bay will be less than 10 ppt and a steep gradient occurs near the ocean entrance. Preliminary analyses of the relationships between 3 ~~~the physical properties of the water column, especially salinity, and those chemical and biological characteristics measured simul- 3 ~~~taneously indicates that there are predictable associations. The following characterization of the three regions within Winyah Bay I ~~~stresses the interactions between components. An assessment of 3 ~~~potential impacts within each of the regions will follow the I ~~~~~~~~~~~~7-11 ecological characterization. Impact predictions will be based upon:I (1) the literature reviewed in the previous section (2) other literature sources with which we are most familiar (Allen et al., 1982, NAS, 1975; and many of the references described therein) and (3) our3 current understanding of the ecology of Winyah Bay. The Upper Bay Tidal amplitude is lowest in the upper bay. The predominant1 direction of water flow is toward the ocean, especially following major3 storms when freshwater inflow is at the maximum level. Although the effect of the flooding tide may be detected many miles upstream,3 increases in river depth are more often the result of a backing up of the freshwater inlfow than to a penetration of salt water. LittleU vertical salinity stratification was evident at any of the river stations except in the lower Sampit River where relatively high salinity water'remained near the bottom. Salinity near the bottom of the ship3 channel outside of the Sampit River was often lower than that at the bottom of Georgetown Harbor.3 There appears to be little doubt that the source of nitrogen for the estuary is the rivers. High concentrations of phosphorus also3 occurred in the upper bay. Despite 'high levels of nutrients, chlorophyll a and carbon concentrations in this region were low relative to theI middle and lower bay. Dec--eased secchi disk visibility in the upper bay3 7-121 was primarily due to high concentrations of fine mud/clay particles and tannins which originated from further upstream. Low light penetra- tion and low salinity apparently minimize phytoplankton production even in the presence of high nutrient concentrations. Additionally, the oceanward flow of surface water prohibits the establishment and maintenance of resident phytoplankton populations in this area. Attached benthic diatoms are, however, abundant along the shore zone and on the marsh surface. Total zooplankton densities were also lowest in the upper bay, especially during major periods of freshwater inflow. There are relatively few freshwater zooplankton species in South Carolina's coastal rivers, and those that were collected in the upper bay during high flow conditions were not abundant. Freshwater cladocerans, rotifers, and insect larvae were collected when the upper bay was essentially freshwater, but during lower flow conditions, the copepods Halicyclops and Eurytemora were more abundant in the upper bay than anywhere else in the estuary. Acartia, the most important copepod in the estuary, was usually present in the upper bay, but densities decreased to zero during periods of high freshwater inflow. Con- spicuously absent from the upper bay, even when salinities were highest, were at least four other copepod species which were abundant near the ocean. Each species of copepod was more abundant in one region than another, but their abundance in all regions varied significantly from season to season. With the exception of the larvae of a few low salinity invertebrates, 7-13 meroplankton was never abundant in the upper bay. Crab zoea (Uca and Rithropanopeus) were important summer constituents of the upper Sampit River zooplankton. Barnacle nauplii and polychaete larvae densities were also high at the river stations at times. Short lived peaks of high densities of only a few species characterized the upper bay meroplankton. Among the epibenthic crustaceans, amphipods were most important in the rivers and upper bay. Gammarid amphipods were patchy in their distribution, but local populations such as those in the Pee Dee River were apparently large. Habitat specificity accounts for large differences in abundance between adjacent areas. Amphipod species composition in the upper bay is different than that in high salinity areas, and it is unlikely that populations move between regions of Winyah Bay. Mysids were also abundant in the upper bay, especially in the bottom waters of the lower Sampit River. The marine-brackish water mysid Neomysis was most abundant at this location when river flow was minimal, and it was absent only when salinities were below about 5 ppt. No other mysid species were collected in the upper bay. Aggregations of Neomysis are highly motile and are capable of selecting suitable habitats within the region. Deep relatively high salinity bottom water in Georgetown Harbor was inhabited by higher densities of mysids than surrounding river and ship channel habitats. Shrimp larvae densities were higher in the lower Sampit River than anywhere else in Winyah Bay possibly because of t ,e presence 7-14 of saltier water. Larvae of the grass shrimp Palaemonetes, which occurs in high densities along the river banks, piers, and ricefield ditches, dominated all shrimp larvae collections in this area. Den- sities in the ship channel were somewhat lower. Upper bay densities of fish eggs and larvae were lower than those from more saline areas. Few species of freshwater or marine fishes produce early life stages which develop in low salinity regions of an estuary. Although some species such as catfishes, gars, and minnows reproduce in the upper bay, they do not produce young which inhabit river bottoms or major channels. Fish larvae and juvenile fishes are much more abundant in shore zone and rice- field ditch habitats, but these areas were not sampled in the pre- sent study. Sciaenid and other brackish-marine fishes move to low salinity areas only after completing their early life stages in more saline regions. It is also likely that the low densities of larval fishes in upper Winyah Bay are related to low concentrations of chlorophyll and low zooplankton densities. Potential Impacts in the Upper Bay Effects of chronic oil pollution within the Sampit River would probably be minimal during the first 1-2 years of plant operation. Baseline studies within Winyah Bay indicate that current water column concentrations in the rivers and bay are very low (Bidleman and Svastits, 1983). It is possible, though, that hydrocarbons and 7-15 other pollutants normally associated with runoff from municipal areasI are having some effect upon localized benthic populations within the Sampit River. However, sampling of benthos within several locations in the Sampit River must be conducted before any such effects can be quantified. Since so little information is currently available, we consider a thorough study of the benthos and sediment chemistry ofU the Sampit River absolutely essential to the assessment of potential impacts of an oil refinery. Routine discharges from plant operation will result in the buildup of hydrocarbons in bottom sediments of the Sampit River to levels which would have detrimental effects upon local biota. High3 turbidity in the rivers (especially the presence of fine mud and3 clay particles in the water column) will only exacerbate the process since heavier oil fractions will floculate with particles and accum- ulate on the bottom. Effects of routiine operation will be most noticeable in areas nearest the effluent discharge. However, these3 effects will be detected throughout the Sampit River system as oiled sediments spread along the bottom. Suspension of bottom sedimentsI by tidal action and river flow will eventually result in a patchy distribution of oiled sediments throughout much of the Sampit River system and portions of the upper bay. Oiled particles will also3 enter the uppter bay as a result of runoff from dredged sediments (from Georgetown Harbor and the ship channel) which are deposited3 in spoil areas between the Waccamaw and Pee Dee River bridges and on Hobcaw Barony, across the bay. Through this mechanism, petroleumI 7-16 pollutants will become widely distributed within the estuary. Acute oil spills, depending upon the size and location of the spill,could possibly affect much of the Sampit River system and por- tions of the upper estuary. Large oil spills in the upper portion of Winyah Bay would affect the middle and lower regions of the estuary. Because of the net flow of water toward the ocean, oil spills in the upper bay are more likely to impact lower portions of the bay than riverine habitats far up the Waccamaw and Pee Dee Rivers. However, under certain conditions spills would be transported to marshes upstream of the bridges. Chronic and acute oil pollution in the upper bay would also result in decreased nutrient concentrations within the system. Benthic communities would experience drastic declines. Concomitant declines in rates of remineralization of nutrients by the benthos would result in decreased nutrient availability. Such effects would be most noticeable in the Sampit River since its watershed is much smaller and receives less phosporus and nitrogen nutrients from agricultural runoff than the other rivers. Primary production in the water column would probably increase as a result of the destruction of herbivore populations. Some restructuring of the phytoplankton community would be expected as highly sensitive species are destroyed and other less sensitive species experience significant increases. The most dramatic detri- mental effects upon primary producers would be the destruction of intertidal marsh plants which receive direct oiling. Plant communities 7-17 along the shore zone and adjacent to the rice field ditches would be expected to experience the most drastic declines. Pertubation of the marshes would not only result in the overall reduction of primary production, but it would eliminate irreplacable habitats for major estuarine invertebrates, fishes, and birds. Species diversity in the zooplankton community would decrease since most species are very sensitive to hydrocarbons. Less sensitive species such as Acartia tonsa, which is generally least abundant in upper portions of the estuary, may assume a greater role throughout much of the year as other species are reduced in numbers. However, total zooplankton numbers and biomass in the upper regions of the bay may decrease by as much as 70-80 %. The zooplankton community would be dominated by only a few species which may be abundant seasonally. Amphipod populations, which were most abundant in the rivers and upper bay, would probably be eliminated or severely reduced since they are extremely sensitive to hydrocarbons. Crustacean larvae, especially shrimp larvae which were more abundant in the Sampit River than any other site sampled in Winyah Bay, are generally very sensitive to petroleum and would probably experience dramatic decreases in abundance. Crab zoeae, which are important constituents in the upper Sampit River, would also be affected. Barnacle nauplii and other members of the meroplankton which are important at the river sites would probably not be affected as severelyas other groups since they spend less of their lives as plankton and are generally, as a group, less sensitive to hydrocarbons. 7-18 I ~~~Mysids were very abundant in the upper bay and often dominated the 3 ~~~epibenthic community. Although mysids are highly motile, their proximity to contaminated bottom sediments throughout their entire life cycle make them particularly susceptible to oil pollution. Damage to larval and juvenile fish populations would be greatest in the shore zone and rice field ditch habitats where they are known to be most abundant. Extensive acute oil pollution would result in I ~~~massive depletions of fishery stocks. . Affects of chronic oil pollution would inevitably result in a decline of commercial and recreational catches. Tainting of fish flesh from ingestion of oiled prey items 3 ~~~and direct exposure to oil could become a serious problem and result in severe financial hardship to local fishermen (McIntyre, 1982). Many of the hydrocarbons'associated with refinery effluents are known to be carcinogenic and may constitute a significant long term human 3 ~~~health hazard. I ~~~The Middle Bay The region which extends from the Belle Isle-Frazier's Point 3 ~~~constriction of Winyah.Bay to the Shell Banks near the narrow ocean end is physically the most complex region. Subsections of the middle bay such as the shallow expanse of Mud Bay, the narrow high velocity ship channel, and secondary channels indicate the diversity of habitats I ~~~in this region. The extent to which freshwater inflow and saline tidal waters mix at any location is the result of many inte...acting factors 1*~~~~~~~~~ ~~7-19 including bathymetry, runoff, tide stage, tide amplitude, and wind:; conditions. Riverine inflow generally moves seaward along the sur- face, even when more saline bottom waters are moving upstream with the flooding tide. Salinity stratification is most distinct in the ship channel. More thoroughly mixed water occurs around the marsh islands and in Mud Bay. Low current velocities, low secchi disk visibility, and high sedimentation rates characterize the Mud Bay area and these features contrast sharply with the dynamic tidal patterns of the major creeks which connect the northern side of Mud Bay to North Inlet. Mud'Bay had higher concentrations of nitrogen and phosphorus than the central portion of the middle bay where amounts of all con- stituents were highly variable. Chlorophyll a and carbon concentra- tions were generally highest in the middle bay where high nutrient concentrations and complex circulation patterns probably enhanced production. Due to the lower salinity of the surface waters along the axis of the estuary, primary production was lower in the chan- nels than in the shallows. Overall densities of total zooplankton in the middle bay were intermediate between the rivers and ocean; densities and species composition were also most variable here. Acartia, a truly euryha- line copepod, usually dominated collections throughout the middle bay and was more abundant there than in other regions of the estuary. During periods of major inflow, Acartia densities decreased and Eurytemora and Halzcyclops densities increased. During medium and 7-20 low freshwater inflow conditions, the marine copepods Parvocalanus, Pseudodiaptomus, Oithona, and Euterpina were more abundant in the middle bay. Marine forms were usually most abundant in the high salinity bottom waters in the ship channel. Densities of copepods, particu- larly Acartia, were often highest at the shallow open water stations in Mud Bay, but densities of meroplankton such as crab zoeae, barnacle nauplii and cyprids, and polychaete and mollusk larvae were often low in these areas. Densities of these invertebrate larvae were usually higher in secondary channels such as EP and TC. Seasonal fluctuations in abundance were significant for all zooplankton constituents, but distributions within the estuary at any time were closely related to the salinity regime. Epibenthic sled studies indicated that Mud Bay was of primary importance to the estuary as a nursery ground for fishes and shrimps. Highest densities of fish eggs and penaeid shrimp postlarvae and second highest densities of fish larvae and amphipods were found in this area. The tidal creeks NMF and SJ were equally important. Channel stations in:.the middle bay yielded the highest densities of mysids and fish larvae. Almost all species of fish larvae were collected in all of the middle bay habitats, but species composition and abundance were highly variable. The high densities of pericarid crustaceans and copepods in the middle bay are most likely related to the high chlorophyll concentra- tions typical of this region. Rich benthic communities and high 7-21 I numbers of planktivorous medusae, menhaden, and mullet are related to the high productivity of this brackish area. Despite the complexity of the middle bay, biological activity appears to be greater than elsewhere in the system. This productivity is manifest in the ability 3 of a small number of species which tolerate a wide range of physiolo- gical conditions to utilize the large amounts of organic material I which are synthesized and accumulate in this region of the estuary. Potential Impacts in the Middle Bay The impacts of acute oil spillage in the middle region of the bay would probably have the most disastrous effects of any area in the Winyah Bay system. The presence of large expanses of complex and highly productive habitats make this region particularly susceptible to petroleum impacts. High current velocities near the ship channel would result in the rapid spreading of oil from a spill throughout the middle and lower bay. Vast areas of aquatic macrophytes are present wibhin the Thousand Acre Ricefield complex and along the periphery of Mud Bay. Water entering No Man's Friend and South Jones Creeks inundate hundreds of acres of Spartina alterniflora marsh within the North Inlet system. An oil spill in the middle bay could seriously affect this highly productive community and significantly reduce the valuable habitat it provides for the biotic community. High sedimentation rates and low current velocities within Mud Bay would rapidly increase the rate at which o)il is incorporated into 3 7-22 1 the bottom sediments. Mud Bay appears to harbor a highly productive benthic community as evidenced by the higher nutrient concentrations in the area. Remineralization of nutrients by benthic organisms would be severely depressed by oil pollution and result in lower availability of nutrients to primary producers and consumers. Phytoplankton may experience rapid population increases in this area as a result of decimation of herbivore populations. Acartia tonsa populations would likely continue to dominate in the middle region of the estuary after an oil spill. However, species diversity would decrease drastically as other more sensitive zooplankton species are reduced in numbers. Temporary members of the zooplankton community such as crab zoea, barnacle nauplii and cyprids, and molluskan larvae would probably be most affected at areas near mid-channel and EP. Mud Bay also plays an extremely important role as a nursery ground for fishes, crabs, and shrimps. The high population densities normally encountered in this area would be severely reduced following an oil spill. Such an occurrence would have estuary-wide implications. Continued resuspension of bottom sediments in Mud Bay would serve as a mechanism for long-term contamination of the local plant and animal communities. The abundant amphipod populations in Mud Bay would be particularly susceptible to oil pollution and may be substantially reduced.. Mysids and fish larvae which were most abundant in the middle bay would decline in numbers. Although densities would be expected to increase during recovery from an oil spill, some species which are 7-23 exposed to contaminated bottom sediments throughout their life cyclesI may take several years to return to normal levels.I Perhaps the'greatest danger of an oil spill in this area relates to the trapping of oiled sediments in Mud Bay. Such an event could be expected to cause impacts for many years or decades as a result of resuspension in the water column. Also, damage to the region wouldI inevitably be reflected in decreased catches of commercially important fishes, crabs, and shrimps. Damage to shellfish resources and fisheryI nursery habitats in North Inlet would result from the transport of oil residues and sediments through NMF and SJ1 Creeks. Because of the special characteristics of the middle bay; even a relatively small spill or the persistence of low concentrations of petroleum hydrocarbons would have serious adverse effects. The Lower Bav Tidal amplitude and current velocities are greatest in the ocean dominated lower region. During periods of major freshwater inflow, surface water masses with salinities below 20 ppt fl'ow to the ocean entrance to Winyah Bay, but strong tidal currents inhibit stratifica- tion in this region. Water clarity was always greatest in the lower bay, a feature probably related to low suspended particle and chloro-I phyll concentrations. Nitrogen and phosphorus concentrations were consistently lower in this region, which indicates that ocean waters are relatively poor in nutrients and riverine nutrient inputs are 7-241 depleted or diluted before reaching the ocean. Physical and chemical characteristics are similar to those at the mouth of North Inlet. Total zooplankton densities were generally higher in the lower bay than further upestuary. Copepods were also the most important taxa near the ocean, but the diversity of species was much greater. Acartia was not nearly as important as it was in the middle bay except when it was displaced to the more seaward regions during major inflow. Halicyclops, a low salinity copepod, only occurred during the major runoff in January. During most flow conditions, marine copepods such as Parvocalanus, Oithona, Pseudodiaptomus, Euterpina. and Centropages were present in densities which changed from season to season. Barnacle larvae densities were usually high especially during periods of salinity stratification. Nauplii densities were higher at the surface and cyprids were more abundant near the bottom. Relatively low numbers of zoeae were present in the lower bay, but megalopae densities near the bottom were the highest of any region. Peak densities of mollusk and pdlychaete larvae were observed near the ocean. The lower bay was also the highest density area for chaetognaths, echinoderm larvae, and appendicularians. In general, summer species diversity was highest near the ocean. Total motile epibenthos densities were also highest in the lower bay. The largest variety of pericarid and decapod crustaceans occurred in high salinity areas throughout the year. Lowest density and diversity values were recorded during periods of maximum inflow. Intermediate densities of mysf is, amphipods and fish larvae occurred there. Although 7-25 shrimp larvae densities in the lower bay were the lowest in the estuary during the 1981-82 cruises, peak densities occurred there during the 1980-81 cruises. Isopods, cumaceans, sergestid shrimps, and postlarval penaeid shrimps were usually most abundant in lower bay collections. f Although early developmental stages of most fishes, crabs, and shrimps were collected in relatively high densities during the warmest months, it is likely that most motile forms moved to more productive, less turbulent habitats such as those described for the middle bay. AdultsI of most crustacean and finfish species of commercial importance repro- 3 duce in the ocean. Larval white and brown shrimp, blue crabs, mullet, spot, croaker, and flounder enter the estuary and move to iiursery areas within the system. Young shad, sturgeon, and striped bass, spawned well up the rivers, move to more saline nursery areas as they develop. There3 appears to be little doubt that middle bay habitats are essential for the completion of the life cycles of almost'all major coastal fisheryI species. Although there is a great deal of biological activity in the3 lower bay, this area may be beat categorized as the corridor of movement between ocean and middle bay habitats. Few motile forms appear to reside5 in the dynamic lower bay region. Potential Impacts in the Lower Bav High current velocities in the lower bay would rapidly spread any oil from a spill over a large distance upestuary or to the nearshore coastal environment depending upon tide and wind conditions. Low3 7-26 nutrient concentrations and phytoplankton densities near mid-channel in the lower portion of the estuary would probably not be significantly affected by oil spillage. The greatest damage to primary producers and nutrient regimes in the lower bay would be felt if oil entered marshes on Cat, South and North Islands. Oiled vegetation would experience massive mortality and nutrient concentrations would concomitantly decrease. Rich benthic communities which are present in these areas would be seriously damaged. Recovery from a major spill would take more than a decade. High species diversity of zooplankton in the lower bay would de- crease as more sensitive species were replaced by those less sensitive. However, zooplankton populations would not be expected to experience serious long-term effects since recruitment from adjacent near shore and upper estuary sites would be rapid. Effects on the abundant mero- plankton in the lower estuary including crab magalopae, barnacle nauplii, and echinoderm larvae would be similar to those observed for other mem- bers of the zooplankton community; however, if a spill occurred during the peak reproductive period of some species, long term effects on the populations would result. Populations of crustacean larvae including shrimps and crabs which were very abundant in the lower bay would be affected by an oil spill. Since most shrimps, crabs and larval fishes migrate to more suitable nursery grounds near the middle of the estuary and do not feed for prolonged periods in the lower bay, impacts to these organisms would probably be less severe here than at sites lc-zated further up the 7-27 estuary. Also, low turbidity and high current velocities would likelyI reduce the buildup of hydrocarbons in the sediments at the ocean end5 of the estuary. Therefore, unless oil entered low-energy marsh habitats and protected shore areas, severe and long-term ecological damage to3 benthd~s and plankton in the lower bay would not be expected. Oil deposited on the jetties and sandy beaches would have severe reper- 1 cussions for populations peculiar to these habitats. A survey of the recent literature and integration with our presentI knowledge of Winyah-Bay indicate that highly productive areas in the middle bay / North Inlet and similar areas adjacent to the river sites (especially the shore zone and'ricefield ditch habitats) would experi-3 ence the most severe effects to the invertebrate and vertebrate popu- lationis should an oil spill occur. Effects from chronic oil pollution may not be detected during the first year or two of plant operation; however, significant environmental degradation including substantiala decreases in local commercial and recreational fisheries will eventually3 result from the chronic discharge of petroleum into the upper bay. 7-281 LITERATURE CITED Alden, R. 1977. Zooplankton, Chapter V, p. V-1-174, In: Center for Natural Areas. A summary and analysis of environmental informa- tion on the Continental Shelf and Blake Plateau from Cape Hatteras to Cape Canaveral. Volume i, Book 1. B.L.M. Contract No. AA 550-CT7-39. Allen, D.M., S.E. Stancyk, and W.K. Michener, 1982. Ecology of Winyah Bay, SC and Potential Impacts of Energy Development. Baruch Inst. Spec. Pub. No. 82-1. 275 pp. American Public Health Association. 1981. Standard methods for examination of water and wastewater. APHA. Washington, D.C. 1134 pp. Anderson, J.W., J.M. Neff, B.A. Cox, H.E. Tatem, and G.M. Hightower. 1975. Characteristics of dispersions and water-soluble extracts of crude and refined oils and their toxicity to estuarine crustaceans and fish. Mar. Biol. 27:75-88. Bidleman, T.F. and A.C. Svastits. 1983. Baseline studies of petroleum hydrocarbons in Winyah Bay. Final report to the Coastal Energy Impact Program, Division of Natural Resources. Columbia, SC. 59 pp. Bloomer, D.R. 1973. A hydrographic investigation of Winyah Bay, South Carolina and the adjacent waters. Masters Thesis, Georgia Institute of Technology. 57 pp. Bowman, T.E. 1971. The distribution of calanoid copepods off the south- eastern U.S. between Cape Hatteras and southern Florida. Smithsonian Contr. Zool. 96:1-58. Brodersen, C.C., S.D. Rice, J.W. Short, T.A. Mecklenberg, and J.F. Karinen. 1977. Sensitivity of larval and adult Alaskan shrimp and crabs to acute exposures of the water-soluble fraction of Cook Inlet crude oil. In: American Petroleum Institute. Proceedings of the 1977 Oil Spill Conference (Prevention, Behavior, Control, Cleanup). Washington, D.C. Clark, R.B. 1D982. The impact of oil pollution on marine populations, communities and ecosystems: a summing up. Phil. Trans. R. Soc. Lond. B 297:433-443. CNEXO. 1981. Amoco Cadiz: fates and effects of the oil spill. Paris: Le Centre National pour d'Exploration des Oceans. 881 pp. Cole, G.A. 1975. Textbook of limnology. The C.V. Mosby Company, Saint Louis. 283 pp. L-1 Conservation Foundation, The. 1980. A reconnaissance of the structure and dynamics of the Winyah Bay ecosystem. p. 1-36, In: The Conservation Foundation. Winyah Bay Reconnaissance Study (Techni- cal Supplement). Washington, D.C. D'Elia, C.F., P.A. Steudler, and N. Corwin. 1977. Determination of total nitrogen in aqueous samples using persulfate digestion. Limnol. Oceanogr. 22:760-764. Fanning, K.A. and V.I. Maynard. 1978. Dissolved boron and nutrients in the mixing plumes of major tropical rivers. Neth. J. Sea Res. 12:345-354. Fiore, J. and J.E. O'Brien. 1962. Ammonia determination by automatic3 analysis. Wastes Eng. 33:352. Glibert, P.L. and T.C. Loder. 1977. Automated analysis of nutrients in seawater: a manual of techniques. Woods Hole Oceanogr. Inst. Tech. Rept. WHOI-77-47. 46 pp. Gooch, E.L. 1968. Hydrogen sulfide production and its effect on inorganic phosphate release from the sediments of the Canary Creek marsh. M. Sci. Thesis, Univ. of Delaware. 61 pp. Grice, G.D. 1960. Calanoid and cyclopoid copepods collected from the Florida Gulf Coast and Florida Keys in 1954 and 1955. Bull. Mar. Sci. Gulf Carriib. 10:217-226 Gunkel, W. and G. Gassmann. 1980. Oil, oil dispersants and related substances in the marine environment. Relgolander Meeresunters. 33:164-181. Holm-Hansen, O., C.J. Lorenzen, R.W. Holmes, and J.D.H. Strickland. 1965. Fluorometric determination of chlorophyll. J. Conseil, Conseil Perm. Intern. Exploration Mer. 30:3-15. Jacobs, J. 1961. Laboratory cultivation of the marine copepod Pseudodiaptomus coronatus (Williams). Limnol. Oceanogr. 6(4):443-446. Johnson, F.A. 1970. A reconnaissance of the Winyah Bay estuarine zone, South Carolina. S.C. Water Resources Commission. Report No. 4. 36 p. Lance, J. 1963. The salinity tolerance of some estuarine planktonic copepods. Limnol. Oceanogr. 8:440-449. Lewis, J.R. 1982. The composition and functioning of benthic ecosystems in relation to the assessment of long-term effects of oil pollution. Phil. Trans. R. Soc. Lond. B 297:257-267. L-2 Lonsdale, D. and B.C. Coull. 1977. Composition and seasonality of the North Inlet, South Carolina zooplankton. Ches. Sci. 18:272-283. May, J.P. 1982. Oil spill trajectory model for Winyah Bay, South Carolina. Final report to the Coastal Energy Impact Program, Division of Natural Resources. Columbia, SC. 51 pp. McIntyre, A.D. 1982. Oil pollution and fisheries. Phil. Trans. R. Soc. Lond. B. 297:401-411. Moll, R.A. and F.J. Rohlf. 1981. Analysis of temporal and spatial phytoplankton variability in a Long Island salt marsh. J. Exp. Mar. Biol. Ecol. 51:133-144. Murphy, J. and J.P. Riley. 1962. A modified single solution method for the determination of phosphate in natural waters. Anal. Chim. Acta. 27:31. National Academy of Sciences. 1975. Petroleum in the marine environment. Workshop on inputs, fates, and the effects of petroleum in the marine environment, May 21-25, 1973, Airlie, VA Nat. Acad. Sci., Washimgton, D.C. 107 pp. Neff, J.M., J.W. Anderson, B.A. Cox, R.B. Laughlin, Jr., S.S. Rossi, and H.E. Tatem. 1976. Effects of petroleum on survival, respiration, and growth of marine animals. In: American Institute of Biological Sciences. Sources, Effects, and Sinks of Hydrocarbons in the Aquatic Environment. Washington, D.C. 515-559. Olsen, S., M.E.Q. Pilson, C. Oviatt, and J.N. Gearing. 1982. Ecological consequences of low, sustained concentrations of petroleum hydrocarbons in temperate estuaries. Univ. Rhode Island Pub. 30 pp. Oviatt, C., J. Frithsen, J. Gearing, and P. Gearing. 1982. Low chronic additions of No. 2 fuel oil: Chemical behavior, biological impacts and recovery in a simulated estuarine environment. Mar. Ecol. Progr. Ser. 2:179-191. Pomeroy, L.R., R.E. Johannes, E.P. Odum, and B. Roffman. 1969. The phosphorus and zinc cycles and productivity of a salt marsh, p. 412-419. In: D. J. Nelson and F.C. Evans (eds.) Symp. Radioecol., Proc. 2nd Nat. Symp. Ann Arbor, Mich. Reid, G. and R. Wood. 1976. Ecology of inland waters and estuaries. P. Van Nostrand Company. New York, 485 pp. Rice, S.D., J.W. Short, and J.F. Karinen. 1977a. Comparative oil toxicity and comparative oil sensitivity. In: Proceedings, NOAA-EPA Symposium on Fate and Effects ,of Petroleum Hydrocarbons, Pergamon Press, Oxford. L-3 Rice, S.D., J.W. Short, and J.F. Karinen. 1977b. Toxicity of Cook Inlet crude oil to several Alaskan marine fishes and invertebrates. In: American Institute of Biolgocial Sciences. Sources, Effects, and Sinks of Hydrocarbons in the Aquatic Environment. Washington, D.C. 394-406. Rossi, S.S. and J.W. Anderson. 1976. Toxicity of water-soluble fractions of No. 2 fuel oil and South Louisiana crude oil to selected stages in the life history of the polychaete, Neanthes arenaceodentata, Bull Envir. Contain. Toxicol. 12:18-24. a Rossi, S.S., J.W. Anderson, and C.S. Ward. 1976. Toxicity of water- soluble fractions of four test oils for the polychaetous annelids Neanthes arenaceodentata and Capitella capitata. Envir. Pollut. 10:9-18. Russell-Hunter, W.D. 1970. Aquatic productivity: an introduction to some basic aspects of biological oceanography and limnology. Macmillan, New York. 306 pp. Sanders, H.L., J.F. Grassle, C.R. Hampson, L.S. Morse, S. Garner-Price, and C.C. Jones. 1980. Anatomy of an oil spill: long term effects from the grounding of the barge "Florida" off West Falmouth, Massachusetts. J. Mar. Res. 38:265-380. Sandifer, P.A., J.V. Miglarese, D.R. Clader, J.S. Manzi, L.A. Barclay, E.B. Joseph, and M.D. McKenzie. 1980. Ecological characterization of the Sea Island coastal region of South Carolina and Georgia. Vol. III; Biological features of characterization area. U.S. Fish and Wildl. Serv., Office of Biol. Serv., Washington, D.C. FWS/OBS-79/42. 620 pp. Sharp, J.H., C.H. Culberson, and T.M. Church. 1982. The chemistry of the Delaware Estuary: general considerations. Limnol. Oceanogr. 27(6): 1015-1028. I Southward, A.J. 1982. An ecologist's view of the implications 6o the observed physiological and biochemical effects of petroleum compounds i on marine organisms and ecosystems. Phil. Trans. R. Soc Lond. B. 197:241-255. Southward, A.J. and E.C. Southward. 1979. Recolonization of rocky shores in Cornwall after use of toxic dispersants to clean up the "Torrey Canyon" spill. J. Fish. Res. Bd. Can. 35:683-706. Spears, R.W. 1971. An evaluation of the effects of oil, oil field brine, and oil removing compounds. AIME Environmental Quality Conference. Am. Inst. of Mining, Metallurgical, and Pet. Engr., Washington, D.C. ~L-4~! L-4 i I Stefanson, U. and F.A. Richards. 1963. Processes contributing to the nutrient distributions off the Columbia River and Strait of Juan de Fuca. Limnol. Oceanogr. 8:394-410. Strickland, J.D.H., and T.R. Parsons. 1972. A practical handbook of seawater analysis. Fish. Res. Bd. of Can., Ottawa. 310 pp. Sutcliffe, W.H. Jr. 1948. A list of calanoid copepods from the plankton at Beaufort, NC. J.Elisha Mitchell Sci. Soc. 64:234-236. Technicon Industrial Systems. 1972. Nitrate and nitrite in water and seawater. Industrial Method No. 158-71W. Technicon Industrial Systems. 1973. Orthophosphate in water and seawater. Industrial Method 155-71W. Thebeau, L.C., T.W. Kana, and D.D. Domeracki. 1981. Sensitivity of coastal environments and wildlife to spilled oil, State of South Carolina. Final Report. Research Planning Institute. Columbia. 93 pp. Tiner, R.W., Jr. 1977. An inventory of South Carolina's coastal marshes. S.C. Mar. Res. Cent. Tech. Rep. No. 23. 33 pp. Trawle, J.J. 1978. Georgetown Harbor, South Carolina; Report 1, hydraulic, salinity, and shoaling verification; hydraulic model investigation. U.S. Army Engineer District, Charleston, S.;C. Miscellaneous paper H-78-6, Report 1 of a series. Van Bennekom, A.J., G.W. Berr, W. Helder, and R.T. Devries. 1978. Nutrient distribution in the Zaire estuary and river plume. Neth. J. Sea Res. 12:296-323. Vandermeulen, J.H. 1982. Some conclusions regarding long-term biological effects of some major oil spills. Phil. Trans. R. Soc. Lond. B 297: 335-351. Wheeler, R.B. 1979. The fate of petroleum in the marine environment. Exxon Production Research Company Special Report. Woodmansee, R.A. 1958. The seasonal distribution of the zooplankton off Chicken Key in Biscayne Bay, Florida. Ecology 39(2): 247-262. Yentsch, C.S. and D.W. Menzel. 1963. A method for the determination of phytoplankton chlorophyll and phaeophytin by fluorescence. Deep-Sea Res. 10:221-231. L-5 KEY TO APPENDICES I-VII Parameter Unit of Measurement Water Temperature degrees Centigrade (C) Air Temperature degrees Centigrade ( C) Salinity grams/liter (g/l,o/oo ,or ppt) Secchi Disk meters Wind Velocity miles per hour Wind Direction degrees Water Velocity meters/second Conductivity millimhos/cm Total Nitrogen Total Dissolved Nitrogen microgram Atoms Nitrogen/liter Nitrate-Nitrite (ug At. N/1) Ammonia Total Phosphorus Total Dissolved Phosphorus microgram Atoms Phosphorus/liter Orthophosphate (ug At. P/1) Chlorophyll a Phaeo-pigments milligrams/cubic meter Dissolved Organic Carbon (mg/m3) Total Organic Carbon Organism abundance (Appendices IV-VII) is expressed as number/cubic meter. A-1 Appendix I. A. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Pennyroyal Creek Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.8 14.3 7.5 17.7 26.4 29.0 26.9 Bottom 24.6 13.8 7.6 17.5 26.3 28.9 26.9 Salinity Surface 8.0 11.4 0.0 0.2 5.7 1.0 10.6 Bottom 8.3 11.7 0.0 0.5 5.9 1.1 10.6 Secchi Disk 0.65 0.70 0.45 0.58 0.52 0.50 0.40 Total Nitrogen Surface 71.7 77.6 - 87.3 - 63.4 54.5 Bottom 51.1 72.3 54.9 86.8 - 64.9 51.2 Nitrate-Nitrite Surface 14.16 8.23 8.59 26.61 12.97 13.55 0.57 Bottom 14.15 8.18 7.91 26.48 12.79 13.47 0.76 Total Phosphorus Surface 3.0 1.9 - 2.5 - 3.1 1.6 Bottom 3.0 2.1 1.5 2.8 - 3.2 1.4 Orthophosphate Surface 0.56 0.59 0.39 1.01 0.62 0.86 0.81 Bottom 0.49 0.51 0.40 1.04 0.57 1.02 0.95 Chlorophyll a Surface 0.59 2.75 1.06 1.88 2.95 2.55 5.16 Bottom 1.45 1.93 1.30 2.10 2.70 2.36 5.16 Phaeo-pigments Surface 1.62 1.96 1.84 2.25 3.18 2.69 5.17 Bottom 2.00 2.06 2.50 3.37 3.77 4.08 5.67 A-2 Appendix I. B. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Sampit River Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.8 14.1 5.7 16.9 27.2 29.5 27.0 Bottom 24.3 13.3 6.0 16.8 25.5 28.1 26.7 Salinity Surface 7.3 10.3 0.0 0.5 3.9 0.8 9.4 Bottom 11.1 16.4 0.0 4.0 17.1 6.2 19.3 Secchi Disk 0.65 0.65 0.48 0.52 0.50 0.43 0.55 Total Nitrogen Surface 65.7 66.7 87.9 124.1 - 62.2 48.1 Bottom 100.6 93.5 77.5 115.2 - 44.9 Nitrate-Nitrite Surface 13.73 9.67 16.28 28.65 14.15 15.42 0.77 Bottom 11.66 7.99 16.09 28.92 9.86 16.14 0.63 Total Phosphorus Surface 2.8 1.6 1.7 2.0 - 3.2 0.8 Bottom 5.7 9.5 2.6 3.1 - 10.4 1.6 Orthophosphate Surface 0.44 0.37 0.38 1.28 0.66 0.83 0.62 Bottom 0.45 0.47 0.49 1.23 0.53 0.84 0.65 Chlorophyll a Surface 2.80 1.74 1.16 1.88 6.08 4.68 11.97 Bottom 10.03 3.93 1.64 2.71 4.30 20.09 8.60 Phaeo-pigments Surface 2.40 1.30 1.29 1.79 4.20 2.27 4.28 Bottom 14.45 7.96 3.48 3.88 5.64 20.19 6.93 A-3 Appendix I. C. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Pee Dee River Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.7 13.8 5.8 17.0 26.4 29.3 26.8 Bottom 24.3 13.5 5.8 16.0 26.1 28.6 26.4 Salinity Surface 9.6 9.0 0.0 0.0 4.0 0.9 12.5 Bottom 10.6 9.0 0.0 0.0 5.6 1.7 14.0 Secchi Disk 0.55 0.55 0.70 0.58 0.52 0.40 0.58 Total Nitrogen Surface 91.3 86.2 65.8 63.6 - 58.3 53.5 Bottom 65.5 89.2 - 85.3 - 64.9 42.4 Nitrate-Nitrite Surface 13.91 9.44 18.50 29.00 13.96 18.89 5.16 Bottom 13.38 9.54 18.03 28.72 13.46 17.27 4.73 Total Phosphorus Surface 2.2 1.9 1.7 0.1 - 3.0 1.4 Bottom 4.3 2.3 - 2.2 - 3.5 1.1 Orthophosphate Surface 0.36 0.36 0.42 0.71 0.48 1.09 0.76 Bottom 0.40 0.38 0.42 0.91 0.48 0.76 0.76 Chlorophyll a Surface 5.77 1.88 0.64 1.79 2.77 2.44 13.39 Bottom 5.65 2.27 0.90 1.74 5.45 3.78 11.36 Phaeo-pigments Surface 3.23 1.56 0.67 2.05 3.53 2.01 4.88 Bottom 4.74 2.17 1.11 2.12 12.57 3.04 5.81 A-4 Appendix I. D. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Waccamaw River Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.2 13.4 5.7 16.4 26.7 29.6 26.7 Bottom 23.8 13.1 5.4 16.2 26.0 28.3 26.6 Salinity Surface 3.4 4.8 0.0 0.2 1.1 0.0 6.0 Bottom 8.1 7.7 0.0 0.2 3.9 0.0 12.4 Secchi Disk 0.45 0.75 0.75 0'.60 - 0.43 0.60 Total Nitrogen Surface 88.6 100.6 73.4 - - 63.3 47.4 Bottom 66.6 84.7 88.6 - - 67.3 62.1 Nitrate-Nitrite Surface 16.22 11.48 18.85 27.78 16.86 22.02 3.39 Bottom 14.51 11.26 18.62 28.19 14.95 22.24 5.36 Total Phosphorus Surface 2.6 1.7 1.4 - - 3.0 1.4 Bottom 5.7 3.1 0.8 - - 3.4 3.1 Orthophosphate Surface 0.38 0.49 0.37 0.57 0.54 1.74 0.50 Bottom 0.40 0.43 0.58 1.38 0.46 1.42 0.64 Chlorophyll a Surface 2.58 1.04 0.75 1.52 3.93 0.55 10.75 Bottom 6.63 2.02 0.83 1.47 5.45 0.99 17.86 Phaeo-pigments Surface 7.47 0.83 0.68 1.74 3.11 1.10 5.31 Bottom 6.65 3.23 0.70 2.04 18.36 2.61 14.09 A-5 Appendix I. E. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Upper Station Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.9 12.0 4.6 17.6 26.0 28.2 26.6 Bottom 24.7 12.6 4.6 17.1 25.7 27.8 26.7 Salinity Surface 5.3 11.2 0.0 1.9 2.6 0.0 10.6 Bottom 10.1 17.3 0.0 3.0 7.5 10.5 16.7 Secchi Disk 0.65 0.75 0.45 0.65 0.50 0.55 Total Nitrogen Surface 62.9 124.0 66.7 71.2 - 53.4 58.3 Bottom 64.7 86.6 82.9 70.8 - 62.7 59.2 Nitrate-Nitrite Surface 16.56 9.82 24.40 33.38 14.79 19.90 0.09 Bottom 14.09 10.47 24.83 31.14 13.46 17.33 2.03 Total Phosphorus Surface 2.9 1.9 2.0 2.9 - 2.8 1.3 Bottom 3.0 2.6 1.5 1.8 - 4.0 2.2 Orthophosphate Surface 0.42 0.60 0.46 1.61 0.53 0.80 0.64 Bottom 0.36 0.95 0.44 1.87 0.60 0.74 0.69 Chlorophyll a Surface 6.76 1.69 1.00 1.91 5.35 3.58 52.36 Bottom 5.90 2.41 0.77 2.31 3.63 11.77 2.31 Phaeo-pigments Surface 2.66 1.44 0.98 2.31 4.59 3.06 - Bottom 3.34 2.94 0.68 3.01 4.46 6.88 13.78 A-6 Appendix I. F. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Belle Isle Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.8 13.6 5.4 16.8 26.8 28.7 26.5 Bottom 24.7 13.1 5.2 16.3 25.0 28.0 26.3 Salinity Surface 12.1 16.2 0.0 1.0 8.9 3.5 16.9 Bottom 19.3 22.0 0.4 6.0 20.1 13.9 20.8 Secchi Disk 0.65 0.50 0.40 0.43 0.64 0.60 0.58 Total Nitrogen Surface 96.8 78.1 82.2 65.1 - 60.4 42.9 Bottom 87.9 168.6 76.8 127.9 - 69.0 49.2 Nitrate-Nitrite Surface 7.50 8.11 17.53 31.72 11.92 18.71 2.39 Bottom 10.27 5.67 18.56 27.65 6.92 17.39 5.45 Total Phosphorus Surface 2.0 1.6 1.5 2.7 - 2.7 1.1 Bottom 3.5 11.7 1.8 11.5 - 4.7 2.6 Orthophosphate Surface 0.57 0.60 0.36 1.08 0.46 0.54 0.61 Bottom 0.39 0.58 0.30 0.86 0.53 0.63 0.72 Chlorophyll a Surface 6.14 1.25 1.25 3.57 7.50 4.54 17.67 Bottom 5.28 5.63 0.75 3.87 3.44 9.34 9.93 Phaeo-pigments Surface 3.33 1.56 1.65 3.42 4.98 3.09 4.93 Bottom 5.57 15.53 1.00 18.62 9.15 8.76 6.86 A-7 Appendix I. G. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Thousand Acre Sep Nov Jan Mar May. Jul Sep Water Temp. Surface 22.9 12.8 5.3 15.9 25.5 30.8 26.5 Bottom 23.9 12.8 5.3 15.9 25.5 29.5 26.3 Salinity Surface 13.2 16.8 0.0 2.1 17.2 3.2 17.2 Bottom 16.4 17.7 0.0 5.0 17.1 4.3 17.3 Secchi Disk 0.35 0.45 0.55 0.42 0.32 0.40 0.63 Total Nitrogen Surface 53.2 72.3 83.5 62.0 - 63.6 50.8 Bottom 47.5 83.0 42.7 68.3 - 64.5 48.5 Nitrate-Nitrite Surface 10.97 8.41 19.36 30.05 11.65 18.54 1.62 Bottom 10.39 7.67 19.83 27.74 11.50 18.06 1.10 Total Phosphorus Surface 3.6 2.0 1.3 2.3 3.3 5.3 Bottom 3.6 2.2 2.3 3.0 - 3.2 1.8 Orthophosphate Surface 0.33 0.53 0.36 0.79 0.36 0.31 0.74 Bottom 0.40 0.59 0.35 0.98 0.50 0.24 0.61 Chlorophyll a Surface 13.01 2.27 1.20 2.34 8.97 9.94 12.38 Bottom 5.90 1.69 1.11 3.44 8.17 8.33 18.67 Phaeo-pigments Surface 4.84 1.50 1.15 2.81 4.92 5.75 5.35 Bottom 3.11 2.30 1.02 4.41 6.21 6.39 6.81 A-8 Appendix I. H. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Pumpkinseed Island Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.2 12.9 5.0 15.5 25.5 30.0 27.1 Bottom 24.2 12.6 5.1 15.4 25.4 29.6 26.8 Salinity Surface 17.4 22.1 0.0 5.5 16.6 6.4 18.8 Bottom 18.9 23.6 0.0 7.9 18.2 6.2 20.1 Secchi Disk 0.45 0.65 0.25 0.70 0.50 0.45 0.55 Total Nitrogen Surface 80.9 - 63.0 82.7 - 57.9 37.3 Bottom 69.9 82.4 78.2 53.9 - 60.3 38.9 Nitrate-Nitrite Surface 8.17 6.55 20.09 27.27 8.48 15.97 1.51 Bottom 8.77 5.71 19.20 25.23 7.98 15.82 5.40 Total Phosphorus Surface 2.1 - 2.6 1.7 - 2.7 0.8 Bottom 1.8 1.6 1.3 1.6 - 2.9 1.3 Orthophosphate Surface 0.43 0.55 0.32 1.58 0.44 0.28 0.71 Bottom 0.37 0.70 0.33 1.11 0.44 0.59 0.67 Chlorophyll a Surface 8.35 1.64 1.84 1.64 6.08 8.46 9.29 Bottom 7.37 1.78 2.09 2.34 7.99 9.94 10.95 Phaeo-pigments Surface 3.54 1.44 5.78 2.35 5.64 4.69 3.36 Bottom 4.41 1.66 5.19 2.26 8.69 4.46 3.83 A-9 Appendix I. I. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Middle Station Sep Nov Jan Mar May Jul Sep Water Temp. Surface 25.1 12.6 4.9 16.3 26.2 28.9 26.8 Bottom 24.7 13.2 5.1 15.2 24.7 27.5 26.4 Salinity Surface 16.9 21.1 2.7 7.9 12.5 5.9 23.0 Bottom 26.7 31.3 8.4 23.8 25.0 25.5 32.4 Secchi Disk 0.55 0.65 0.35 0.78 0.47 1.00 0.75 Total Nitrogen Surface 76.5 72.4 84.3 55.1 - 48.3 30.0 Bottom 88.5 67.8 76.7 44.2 - 48.0 19.7 Nitrate-Nitrite Surface 9.65 6.69 19.23 26.06 9.09 14.36 4.04 Bottom 7.68 3.18 15.40 9.38 4.41 4.42 1.79 Total Phosphorus Surface 1.7 1.4 2.8 1.9 - 1.8 0.90 Bottom 1.7 1.5 2.4 0.7 - 1.8 0.60 Orthophosphate Surface 0.42 0.69 0.24 1.28 0.35 0.46 0.51 Bottom 0.35 0.36 0.26 0.93 0.41 0.45 0.49 Chlorophyll a Surface 6.88 2.02 1.30 1.81 9.85 10.75 14.00 Bottom 3.56 2.94 4.05 2.58 2.87 8.94 5.64 Phaeo-pigments Surface 2.71 1.65 1.19 2.16 4.87 5.31 3.54 Bottom 3.02 2.86 2.30 1.80 2.43 5.84 3.37 A-10 Appendix I. J. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: The Cut Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.6 13.3 5.6 15.7 26.2 29.5 26.3 Bottom 24.6 13.0 5.6 15.5 25.3 28.5 26.1 Salinity Surface 17.8. 22.2 1.5 9.0 17.8 6.2 20.9 Bottom 21.1 23.4 0.0 12.0 20.0 7.1 22.0 Secchi Disk 0.55 0.55 0.30 0.75 0.70 0.65 - Total Nitrogen Surface 92.2 81.9 77.3 50.7 - - 37.0 Bottom 81.6 70.2 79.7 57.1 - - 40.1 Nitrate-Nitrite Surface 8.35 6.05 18.91 23.94 8.00 16.71 5.53 Bottom 7.88 5.59 18.47 20.82 6.77 16.59 5.45 Total Phosphorus Surface 1.9 1.5 4.1 - - - 3.4 Bottom 1.6 2.0 4.9 2.2 - - 3.8 Orthophosphate Surface 0.33 0.73 0.23 1.31 0.48 0.28 0.57 Bottom 0.29 0.66 0.26 0.78 0.51 0.88 0.71 Chlorophyll a Surface 9.58 2.41 1.59 2.05 4.49 6.81 8.88 Bottom 4.79 1.93 1.78 2.10 3.01 7.23 9.33 Phaeo-pigments Surface 4.16 1.71 3.03 1.78 3.66 4.08 4.96 Bottom 3.29 2.96 3.74 4.27 4.96 5.67 10.05 A-11 Appendix I. K. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Esterville Plantation Sep Nov Jan Mar May Jul Sep Water Temp. Surface 25.2 13.8 6.1 18.9 26.9 28.7 26.0 Bottom 24.6 13.1 7.1 15.5 24.9 28.0 26.0 Salinity Surface 11.2 24.8 3.7 2.2 22.2 2.0 13.0 Bottom 20.5 26.8 25.5 22.1 24.9 2.3 16.7 Secchi Disk 0.45 0.65 0.35 0.58 0.58 0.45 0.73 Total Nitrogen Surface 60.9 108.2 67.3 63.4 - 63.0 - Bottom 86.6 76.4 192.1 - - 69.1 57.1 Nitrate-Nitrite Surface 12.72 5.09 15.84 30.10 6.69 18.37 4.32 Bottom 7.21 4.07 7.01 11.17 4.33 18.62 2.37 Total Phosphorus Surface 2.8 1.5 2.0 2.2 - 3.2 - Bottom 6.7 1.3 14.2 - - 5.1 2.9 Orthophosphate Surface 0.37 0.71 0.22 0.77 0.47 0.47 0.50 Bottom 0.37 0.74 0.34 0.72 0.51 1.11 0.42 Chlorophyll a Surface 8.44 2.27 1.78 3.13 10.38 3.40 13.39 Bottom 8.79 2.31 17.59 2.29 3.63 3.92 13.79 Phaeo-pigments Surface 6.11 1.72 1.98 2.06 4.67 3.01 4.70 Bottom 14.02 2.04 25.73 2.29 5.21 8.29 10.02 A-12 Appendix I. L. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Mud Bay Sep Nov Jan Mar May Jul Sep Water Temp. Surface 25.1 13.9 6.0 16.8 27.0 28.5 25.7 Bottom 24.7 13.5 6.0 16.5 23.8 28.1 26.0 Salinity Surface 16.9 31.9 1.8 10.0 21.5 8.8 23.6 Bottom 26.7 32.7 4.0 11.5 32.4 9.3 23.8 Secchi Disk 0.55 0.75 0.30 0.60 0.62 0.42 0.48 Total Nitrogen Surface 76.5 48.2 74.4 51.7 - 50.8 33.9 Bottom 88.5 75.4 78.1 53.0 - 67.8 41.9 Nitrate-Nitrite Surface 9.65 2.00 18.07 21.90 .6.83 15.36 4.42 Bottom 7.68 1.38 12.37 21.01 1.25 15.25 4.24 Total Phosphorus Surface 1.7 0.9 8.8 1.9 - 2.2 1.1 Bottom 1.7 1.4 5.0 2.2 - 4.6 1.8 Orthophosphate Surface 0.42 0.41 - 0.78 0.51 0.59 0.64 Bottom 0.35 0.39 0.48 0.83 0.38 0.66 0.59 Chlorophyll a Surface 6.88 2.60 2.70 2.05 3.32 2.66 5.92 Bottom 3.56 2.80 9.50 2.56 2.70 4.46 8.81 Phaeo-pigments Surface 2.71 1.84 4.34 2.89 2.69 4.55 8.11 Bottom 3.02 2.51 12.33 3.49 3.53 15.29 8.28 A-13 Appendix I. M. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Shell Bank Sep Nov Jan Mar May Jul Sep Water Temp. Surface 24.8 13.9 5.6 15.2 24.1 28.6 26.1 Bottom 24.7 13.5 5.8 14.8 23.0 27.9 26.3 Salinity Surface 32.2 33.2 3.8 22.5 32.7 14.1 31.7 Bottom 32.2 33.9 6.3 25.5 33.5 19.3 31.5 Secchi Disk 1.15 0.85 0.30 0.63 0.88 0.55 0.58 Total Nitrogen Surface - 60.9 73.5 41.6 - 48.5 27.2 Bottom 65.9 75.0 96.6 44.8 - 43.9 27.8 Nitrate-Nitrite Surface 0.14 1.67 17.45 8.88 1.47 13.90 1.77 Bottom 0.85 0.96 17.12 7.38 0.66 9.17 1.75 Total Phosphorus Surface - 0.8 7.8 0.9 - 2.0 1.0 Bottom 1.2 1.4 6.1 0.7 - 2.3 1.1 Orthophosphate Surface 0.16 0.43 0.27 2.27 0.29 0.59 0.62 Bottom 0.29 0.33 0.29 0.87 0.83 0.63 0.56 Chlorophyll a Surface 4.42 1.88 3.56 2.87 2.00 1.78 2.96 Bottom 3.69 2.22 5.77 2.92 1.81 1.31 2.96 Phaeo-pigments Surface 1.81 1.47 6.48 1.91 1.36 4.67 5.62 Bottom 2.32 2.49 10.16 2.14 1.59 8.09 6.18 A-14 Appendix I. N. Physical/chemical characteristics and plant pigments during extensive and intensive series of cruises within Winyah Bay (1981 - 1982). Location: Mother Norton Sep Nov Jan Mar May Jul Sep Water Temp. Surface 25.4 13.3 5.8 14.7 24.2 29.0 26.5 Bottom 25.0 13.3 6.6 14.6 22.8 26.3 26.5 Salinity Surface 31.4 35.3 21.5 27.0 32.4 31.3 32.8 Bottom 33.6 35.3 33.3 30.0 34.1 34.2 33.3 Secchi Disk 1.05 0.75 0.28 0.47 0.57 0.95 0.75 Total Nitrogen Surface 51.1 76.2 74.5 31.2 - 27.0 25.0 Bottom 38.5 49.0 64.9 34.4 - 28.6 23.5 Nitrate-Nitrite Surface 1.60 1.23 10.13 5.04 0.75 3.22 .1.01 Bottom 0.72 1.31 1.53 2.53 0.32 0.55 0.96 Total Phosphorus Surface 1.3 1.0 3.0 0.7 - 0.9 1.0 Bottom 1.3 0.8 3.4 0.8 - 1.6 1.0 Orthophosphate Surface 0.11 0.22 0.17 0.40 0.35 0.12 0.36 Bottom 0.08 0.17 0.14 0.40 0.22 0.24 0.43 Chlorophyll a Surface 3.56 3.69 8.11 2.82 5.47 4.27 8.47 Bottom 6.39 3.81 7.99 3.14 5.10 9.94 9.91 Phaeo-pigments Surface 1.63 1.40 3.67 1.83 2.44 3.56 5.25 Bottom 2.73 1.62 6.33 3.10 3.05 7.60 5.37 A-15 Appendix II. A. Physical/chemical characteristics and plant pigments during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Water Date Time Air Wind Wind Velocity Temp. Vel. Dir. Tide S B 9-18 1000 27.0 5.0 225 Flood 0.53 0.17 1100 28.0 7.0 180 Flood 0.25 0.10 1200 28.0 11.0 190 Ebb 0.85 0.40 1300 29.0 11.5 190 Ebb 1.05 0.90 1400 29.0 13.0 230 Ebb 1.40 1.10 | 1500 28.0 13.5 190 Ebb - - 1600 27.5 14.0 190 Ebb 1.15 0.95 1700 28.0 15.0 190 Ebb 0.58 0.52 1800 27.5 15.0 190 Flood 0.10 0.20 1900 26.0 15.0 202 Flood 0.65 0.55 2000 26.0 10.0 180 Flood - - 2100 26.0 17.0 180 Flood - - 2200 26.0 12.5 180 Flood 0.60 0.45 2300 26.0 9.0 190 Slack 0.25 0.10 9-19 0000 26.0 15.5 202 Ebb 0.55 0.40 0100 25.0 13.5 247 Ebb 1.05 0.80 0200 25.0 10.0 225 Ebb 1.45 1.05 0300 25.0 5.0 202 Ebb - 0400 25.0 5.0 202 Ebb 1.15 0.85 0500 24.0 <5.0 Var. Ebb 0.55 0.35 0600 24.0 <5.0 Var. Slack - - 0700 24.0 <5.0 Var. Flood - - 0800 25.0 0.0 - Flood - - 0900 25.0 <5.0 Var. Flood - - A-16 Appendix II. A. Physical/chemical characteristics and plant pigments (continued) during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Water Date Time Air Wind Wind Velocity Temp. Vel. Dir. Tide S B 9-19 1000 26.0 <5.0 Var. Flood - - 1100 27.5 7.0 60 Flood - - 1200 29.0 10.0 180 Slack - - 1600 25.0 15.0 220 Ebb - - 1700 25.0 15.0 180 Ebb - - 1800 25.5 15.0 90 Ebb - - 1900 25.2 11.0 215 Flood - - 2000 25.0 11.5 225 Flood - - 2100 25.0 10.0 200 Flood - - 2200 25.0 11.5 210 Flood - - 2300 25.0 12.5 180 Flood - - 9-20 0000 25.0 14.5 190 Flood - - 0100 26.0 13.0 190 Ebb - - 0200 25.5 14.0 210 Ebb - - 0300 25.5 14.5 210 Ebb - - 0400 25.0 13.0 210 Ebb - - 0500 25.0 11.0 230 Ebb - - 0600 25.5 11.5 220 Ebb - - 0700 25.0 12.0 190 Flood - - 0800 25.0 11.0 170 Flood - - 0900 26.0 13.0 170 Flood - - 1000 26.0 13.0 170 Flood - - 1100 27.0 13.0 170 Flood - - 1200 27.0 14.0 210 Flood - - A-17 Appendix II. B. Physical/chemical characteristics and plant pigments during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Temperature Conductivity Salinity Date Time S B S B S B 9-18 1000 25.8 26.3 52.1 52.3 33.4 33.5 1100 26.2 26.3 52.5 53.0 33.8 33.8 1200 26.4 26.1 53.2 53.5 33.8 34.5 1300 26.1 26.1 53.0 53.1 33.9 34.0 1400 26.8 26.6 51.4 52.2 32.4 33.2 1500 26.9 26.9 49.1 50.0 30.9 31.4 1600 27.3 27.2 45.0 45.2 28.1 28.2 1700 27.2 27.3 41.1 42.1 25.3 25.9 1800 27.1 26.9 40.7 43.8 25.1 27.1 1900 27.4 26.7 - - 31.2 32.7 2000 - _ - - -_ 2100 27.0 27.0 54.2 54.2 34.9 33.9 2200 26.9 27.0 54.0 54.2 33.9 34.4 2300 26.7 26.6 53.6 53.6 33.7 34.5 9-19 0000 26.7 25.8 53.4 53.5 33.7 33.9 0100 26.8 26.6 53.6 53.9 34.8 34.9 0200 26.6 26.7 53.1 53.7 34.2 34.5 0300 26.8 26.9 49.9 49.9 31.8 31.4 0400 26.6 26.7 45.0 46.0 28.2 29.0 0500 26.9 26.8 41.2 42.0 26.2 26.6 0600 26.5 26.9 39.4 40.3 24.6 25.5 0700 26.7 26.4 41.4 41.8 26.1 25.8 0800 26.5 26.5 51.0 50.8 32.3 32.2 0900 26.2 26.2 48.8 49.0 30.9 31.1 A-18 Appendix II. B. Physical/chemical characteristics and plant pigments (continued) during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Temperature Conductivity Salinity Date Time S B S B S B 9-19 1000 26.1 26.1 50.3 49.1 31.4 31.2 1100 26.3 26.1 50.3 50.9 32.0 32.4 1200 26.2 25.9 50.7 51.2 32.1 32.3 1600 26.4 26.1 42.3 43.4 25.7 26.9 1700 26.5 26.7 40.5 40.4 24.9 25.2 1800 26.4 26.2 35.2 37.5 21.0 22.8 1900 26.0 26.4 38.8 40.3 23.8 25.9 2000 26.7 26.6 45.7 46.7 28.8 29.4 2100 26.5 26.7 51.2 51.4 31.6 32.8 2200 26.4 26.4 51.9 52.2 33.5 33.2 2300 26.4 26.5 51.6 53.3 32.8 34.1 9-20 0000 26.6 26.7 51.7 54.0 32.8 34.6 0100 26.5 26.5 52.8 53.3 33.7 34.1 0200 26.4 26.6 51.8 52.6 33.3 34.0 0300 26.5 26.5 50.2 50.6 32.4 32.5 0400 26.7 26.5 47.2 47.4 30.3 30.1 0500 26.7 26.7 41.0 41.8 25.7 26.2 0600 26.7 26.4 38.8 40.0 24.2 24.3 0700 26.7 26.7 38.5 42.2 24.0 26.7 0800 26.5 26.7 49.2 43.4 28.2 27.8 0900 26.2 26.4 52.0 52.0 33.2 33.4 1000 26.3 26.5 52.5 52.5 33.7 33.7 1100 26.5 26.5 53.6 53.6 34.4 34.4 1200 26.6 26.6 54.6 54.1 33.4 34.8 A-19 Appendix II. C. Physical/chemical characteristics and plant pigments during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Total Nitrate- Dissolved Total Nitrite Ammonia Nitrogen Nitrogen Date Time S B S B S B S B 9-18 1000 0.56 0.32 2.49 1.30 20.2 10.8 - 18.9 1100 0.40 0.24 1.09 2.38 18.4 8.8 9.1 24.1 1200 0.45 0.40 1.79 1.98 - 14.5 19.2 17.6 1300 0.42 0.25 1.01 1.34 13.3 - 19.6 18.1 1400 0.71 0.52 1.28 1.88 14.8 - 22.6 18.8 1500 1.04 0.98 1.26 1.84 12.1 13.2 28.3 14.2 1600 1.63 1.51 1.74 1.68 20.0 16.5 30.6 31.9 1700 1.77 1.87 2.32 1.61 17.0 22.4 27.6 24.1 1800 1.55 1.90 1.48 2.39 23.9 22.6 32.3 30.1 1900 1.61 1.07 2.00 1.41 15.2 22.7 21.2 27.6 2000 0.61 2.03 1.20 1.35 18.9 - 14.6 18.1 2100 0.64 0.42 1.79 1.42 27.9 - 16.0 16.0 2200 0.57 0.36 1.32 1.60 20.9 14.7 - 22.8 2300 0.41 0.32 7.70 2.19 13.4 19.3 16.4 32.1 9-19 0000 0.72 0.45 1.22 6.48 23.0 51.2 17.9 22.9 0100 1.34 0.37 5.08 0.85 48.5 21.8 16.2 19.7 0200 0.88 0.48 9.63 2.50 23.8 19.2 29.0 18.1 0300 0.75 0.91 1.89 2.00 17.5 26.7 18.2 21.7 0400 1.85 1.58 4.36 6.02 41.9 30.9 23.0 26.4 0500 2.12 2.04 2.60 2.40 29.5 28.4 25.7 26.0 060 2.13 2.28 2.08 3.28 29.6 25.5 27.6 31.1 0700 2.21 2.09 3.40 4.48 39.6 31.6 27.1 36.1 0800 1.57 1.46 4.16 2.73 36.6 30.7 23.5 23.1 0900 0.60 0.63 0.00 4.03 13.3 13.7 22.9 20.0 A-20 Appendix II. C. Physical/chemical characteristics and plant pigments (continued) during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Total Nitrate- Dissolved Total Nitrite Ammonia Nitrogen Nitrogen Date Time S B S B S B S B 9-19 1000 0.58 0.44 0.43 0.29 17.4 26.0 19.2 11.2 1100 0.45 0.45 0.72 0.58 15.0 17.0 19.0 22.8 1200 0.69 0.45 2.28 0.31 25.6 22.5 19.6 18.3 1600 3.66 2.26 0.00 4.84 - 29.1 29.1 30.2 1700 1.85 1.85 4.89 1.99 30.4 24.6 33.4 30.7 1800 2.19 2.15 2.43 4.18 23.5 27.0 24.0 31.9 1900 2.31 2.23 1.68 2.33 31.0 29.2 -27.8 31.8 2000 2.20 2.24 2.58 2.43 27.2 29.0 26.0 32.2 2100 0.93 1.07 1.20 0.78 21.6 13.2 31.1 27.2 2200 - 0.84 1.22 1.76 17.0 27.7 18.7 15.2 2300 1.02 0.53 3.36 0.79 19.6 21.3 19.1 25.5 9-20 0000 1.71 0.46 1.28 1.07 17.1 19.7 19.2 26.1 0100 0.93 0.56 1.41 1.36 26.7 19.3 25.8 17.0 0200 1.01 0.89 1.48 2.48 20.1 21.1 23.7 25.2 0300 1.35 1.06 2.07 1.99 18.3 22.4 28.4 31.6 0400 1.69 1.74 2.16 2.51 23.3 21.4 28.6 26.5 0500 2.75 2.52 2.82 2.11 25.6 22.8 28.6 32.6 0600 3.13 3.02 2.26 2.36 34.8 35.5 33.0 41.2 0700 3.14 2.53 2.49 3.46 29.7 24.9 33.0 54.6 0800 2.26 2.49 2.49 1.97 39.7 29.4 36.4 38.7 0900 1.10 1.10 1.22 1.28 24.5 23.6 36.3 60.1 1000 1.11 1.08 1.27 1.79 30.9 16.4 42.4 54.2 1100 0.60 0.65 0.75 1.11 25.7 22.2 35.4 36.4 1200 1.15 0.43 1.77 1.02 35.0 19.4 26.5 68.6 A-21 Appendix II. D. Physical/chemical characteristics and plant pigments during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Total Dissolved Total Orthophosphate Phosphorus Phosphorus Date Time S B S B S B 9-18 1000 0.089 0.208 0.3 0.3 - 0.6 1100 0.118 0.154 0.2 0.4 0.2 0.8 1200 0.214 0.225 - 1.1 0.7. 0.9 1300 0.224 0.750 0.9 - 1.0 0.8 1400 0.818 0.939 2.6 - 0.9 1.0 1500 0.177 0.303 0.2 0.2 1.1 0.5 1600 0.250 0.271 0.4 0.2 1.2 1.3 1700 0.244 0.315 0.3 0.6 1.0 1.1 1800 0.314 0.404 0.3 0.4 0.8 1.4 1900 1.041 0.418 0.2 0.2 0.7 1.7 2000 0.099 0.084 0.5 - 0.6 0.8 2100 0.162 0.241 1.1 - 0.6 0.4 2200 0.285 0.233 0.5 0.3 - 0.9 2300 1.061 1.320 0.0 0.5 0.4 1.7 9-19 0000 0.712 0.420 0.0 2.8 0.4 1.1 0100 0.679 0.356 1.3 0.7 0.5 1.0 0200 0.422 0.446 0.2 0.3 0.8 0.7 0300 0.490 0.531 0.7 0.6 0.8 1.0 0400 1.019 0.971 1.1 1.9 0.7 1.0 0500 1.225 0.717 1.0 0.8 1.1 1.3 0600 0.582 0.572 0.8 0.7 1.0 1.6 0700 0.602 0.647 1.0 0.7 1.0 1.6 0800 0.416 0.331 1.2 0.6 1.0 4.2 0900 0.585 1.141 0.2 0.1 1.0 0.5 A-22 Appendix II. D. Physical/chemical characteristics and plant pigments (continued) during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Total Dissolved Total Orthophosphate Phosphorus Phosphorus Date Time S B S B S B 9-19 1000 0.930 0.751 0.1 0.0 0.5 0.3 1100 0.385 0.325 0.0 0.1 0.6 1.1 1200 0.266 0.250 0.1 0.0 0.6 0.6 1600 1.395 0.670 - 1.1 0.9 1.0 1700 0.943 1.490 0.5 0.3 1.2 1.4 1800 0.866 1.129 0.4 1.1 1.0 1.3 1900 0.624 0.517 0.5 0.8 1.1 1.1 2000 0.412 0.329 1.2 0.5 1.3 1.1 2100 0.421 0.348 0.4 0.2 1.2 1.3 2200 - 0.406 0.1 3.6 0.6 1.0 2300 1.023 1.554 1.0 0.3 0.4 1.0 9-20 0000 0.539 0.368 0.9 0.4 1.2 1.2 0100 0.461 0.462 0.5 1.6 1.1 0.7 0200 0.416 0.277 0.3 0.4 0.5 0.7 0300 1.635 1.312 0.5 0.5 1.2 1.2 0400 1.384 1.614 0.4 0.6 0.9 1.0 0500 0.655 0.600 0.6 1.0 0.9 1.2 0600 0.578 0.635 1.3 1.4 1.2 1.8 0700 0.621 2.481 1.0 0.7 1.3 1.7 0800 1.823 1.687 0.9 0.6 1.2 2.1 0900 1.640 1.091 2.6 0.6 2.2 2.6 1000 0.444 0.391 0.7 2.2 2.7 2.6 1100 0.442 0.419 0.7 0.6 1.7 1.4 1200 0.419 0.359 0.8 0.6 1.8 2.3 A-23 Appendix II. E. Physical/chemical characteristics and plant pigments during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Dissolved Total Organic Organic Carbon Carbon Chlorophyll a Phaeo-pigments Date Time S B S B S B S B 9-18 1000 2.7 2.3 3.7 2.9 3.59 3.80 2.36 2.19 1100 2.7 4.3 2.9 2.8 3.37 4.48 1.86 3.22 1200 3.9 3.8 3.3 3.0 5.16 4.33 2.92 3.93 1300 2.3 2.5 3.6 3.6 3.79 5.43 4.91 4.27 1400 2.6 2.5 3.4 3.4 5.98 5.64 3.59 3.25 1500 3.4 3.6 4.4 4.2 6.33 4.12 2.75 7.01 1600 3.4 3.5 4.2 4.4 7.57 9.63 4.00 3.51 1700 3.8 4.2 4.8 5.2 9.08 9.98 3.88 4.43 1800 4.4 4.8 4.5 4.8 9.01 9.75 6.77 5.64 1900 3.8 3.5 4.2 4.2 6.54 14.61 2.61 11.98 2000 2.8 4.0 2.6 2.7 2.55 2.89 4.23 2.57 2100 3.3 2.8 2.6 2.6 2.76 4.10 3.43 0.94 2200 2.6 3.2 3.1 3.2 2.54 5.92 2.52 7.86 2300 3.1 3.4 2.9 5.6 1.93 5.71 2.12 6.88 9-19 0000 3.7 4.0 3.2 4.6 2.92 6.34 1.91 4.91 0100 - 3.0 3.4 3.3 2.97 4.98 2.51 5.87 0200 3.6 3.8 3.6 3.3 3.06 4.40 2.82 4.74 0300 4.9 4.5 4.0 3.6 3.37 3.65 3.77 4.45 0400 5.1 3.8 4.5 4.5 3..30 3.24 4.15 3.96 0500 4.5 4.6 4.2 5.2 3.21 3.51 3.02 4.19 0600 4.6 5.0 5.0 5.1 3.56 4.06 2.99 5.08 0700 4.2 4.2 4.6 5.0 4.06 4.33 1.95 4.18 0800 - 2.9 4.8 3.9 4.27 5.85 4.69 10.25 0900 2.5 2.5 3.3 3.2 4.47 4.13 3.04 3.01 A-24 Appendix II. E. Physical/chemical characteristics and plant pigments (continued) during intensive 48-hour sampling program at Mother Norton Shoals (September 1982). Dissolved Total Organic Organic Carbon Carbon Chlorophyll a Phaeo-pigments Date Time S B S B S B S B 9-19 1000 2.8 2.5 3.2 3.1 3.16 5.16 1.91 3.42 1100 2.6 3.1 3.5 3.5 2.46 4.20 4.48 4.40 1200 2.8 2.7 3.4 3.3 3.27 6.95 2.63 0.50 1600 - 3.8 4.3 4.8 6.40 6.54 3.24 4.55 1700 3.5 3.8 4.5 4.6 7.57 8.53 4.58 6.31 1800 4.3 4.2 4.8 4.9 6.54 7.71 3.85 4.63 1900 4.3- 4.5 5.0 5.4 4.68 8.19 3.08 5.46 2000 4.4 4.1 4.5 4.1 4.19 5.10 4.06 3.30 2100 3.1 2.9 3.5 4.3 4.75 6.26 4.46 8.83 2200 2.8 3.2 3.2 3.2 3.23 3.31 3.97 2.38 2300 3.1 3.1 3.2 3.8 3.92 4.54 3.15 5.54 9-20 0000 2.6 2.5 3.5 3.2 3.51 6.13 3.50 4.08 0100 3.5 3.2 3.1 3.2 3.15 3.30 3.25 3.74 0200 2.5 3.1 4.3 3.5 3.40 5.23 3.34 4.36 0300 3.1 3.5 4.4 4.3 4.06 4.75 3.90 6.15 0400 5.4 6.2 4.9 4.2 3.17 3.51 4.60 4.75 0500 7.5 6.0 6.4 5.5 3.30 3.37 5.15 5.14 0600 7.5 8.0 5.9 5.8 5.02 4.61 4.56 4.72 0700 6.8 6.3 5.0 5.0 7.01 4.33 4.38 6.12 0800 6.9 7.1 4.5 4.8 3.85 3.51 5.48 5.57 090? 5.5 4.9 4.8 4.8 7.23 7.51 9.18 10.04 1000 6.9 5.5 4.8 5.7 7.44 9.44 9.55 12.82 1100 3.4 5.4 3.5 3.4 5.71 5.71 5.94 6.12 1200 4.5 3.2 3.5 3.7 5.57 7.02 3.88 6.19 A-25 Appendix III. A. Physical/chemical characteristics and plant pigments tabulated by salinity for the special chemistry transect series. Cruise 1. (October, 1981) Total Depth Conduc- Water Ortho- Dissolved Total Salinity S/B tivity Temp. phosphate Phosphorus Phosphorus 0.0 S 0.0 - 0.92 2.0 2.3 0.0 S 0.0 - 1.15 2.8 4.2 2.2 S 3.7 25.6 0.46 1.9 2.4 3.5 S 6.0 25.6 0.40 2.2 2.9 4.6 B 7.7 24.1 0.43 1.4 3.8 4.7 B 8.0 24.5 0.37 1.7 2.7 5.3 S 9.1 25.6 0.39 1.5 2.2 5.4 S 9.2 24.6 0.35 1.6 2.2 6.8 B 11.3 24.5 0.37 1.8 4.6 6.9 S 11.6 24.6 0.33 1.4 2.2 6.9 B 11.6 24.6 - - - 7.5 B 12.4 24.5 0.41 1.4 4.6 11.0 S 17.9 25.0 0.41 1.4 2.0 11.7 S 19.2 25.1 0.36 1.2 2.5 15.6 B 25.0 24.8 0.40 1.7 2.2 15.7 S 25.6 25.6 0.33 1.0 2.2 18.8 B 29.7 24.8 0.40 1.0 2.4 23.6 S 37.8 26.2 0.27 1.0 1.4 24.9 B 38.9 25.0 0.33 0.9 1.4 25.7 S 40.6 26.0 0.28 0.7 1.2 32.0 B 48.9 25.0 0.16 0.4 1.4 32.5 S 29.8 25.2 0.12 0.4 0.9 33.2 B 50.5 25.1 0.50 0.3 1.3 33.5 B 51.1 25.0 0.20 0.5 1.8 34.3 S 51.8 25.4 0.08 0.4 0.6 A-26 Appendix III. A. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 1. (October, 1981) Total Depth Nitrate- Dissolved Total Salinity S/B Ammonia Nitrite Nitrogen Nitrogen 0.0 S 5.75 14.45 68.4 72.1 0.0 S 1.15 6.85 71.3 83.3 2.2 S 2.59 16.95 64.8 76.2 3.5 S 1.71 13.41 70.5 72.8 4.6 B 2.88 15.94 59.9 87.8 4.7 B 2.11 13.44 72.6 87.5 5.3 S 2.90 16.01 64.1 79.6 5.4 S 2.05 15.34 64.6 77.2 6.8 B 2.85 14.89 63.5 95.4 6.9 S 2.24 14.41 61.5 71.2 7.5 B 3.77 14.97 64.4 87.3 11.0 S 4.91 14.74 59.4 68.4 11.7 S 6.14 13.69 57.0 62.5 15.6 B 5.71 11.30 54.2 62.2 15.7 S 4.92 12.61 53.1 54.2 18.8 B 3.96 8.32 39.4 66.2 23.6 S 5.22 6.38 46.9 46.9 24.9 B 6.83 .6.56 41.4 40.5 25.7 S 4.77 4.39 39.0 43.9 32.0 B 2.63 1.51 - 39.3 32.5 S 2.15 3.51 34.4 40.5 33.2 B 3.81 0.86 29.1 35.3 33.5 B 0.96 0.61 21.1 46.0 34.3 S 1.55 0.40 32.4 34.5 A-27 Appendix III. A. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 1. (October, 1981) Dissolved Total Depth Chloro- Phaeo- Organic Organic Salinity S/B phyll a pigments Carbon Carbon 0.0 S 0.83 0.73 21.0 0.0 S 1.01 1.98 32.0 - 2.2 S 8.35 3.08 8.5 - 3.5 S 7.74 2.42 21.5 4.6 B 6.63 1.68 25.0 4.7 B 6.51 2.61 19.0 5.3 S 8.60 2.72 5.5 - 5.4 S 7.37 2.91 20.5 6.8 B 6.63 5.49 18.5 - 6.9 S 5.90 5.42 17.0 7.5 B 6.14 8.29 10.0 11.0 S 4.30 2.51 15.0 - 11.7 S 9.46 4.63 16.5 15.6 B 4.18 2.87 9.5 15.7 S 8.11 3.21 12.5 18.8 B 3.69 4.28 12.0 - 23.6 S 5.41 2.56 10.0 24.9 B 3.93 2.42 10.5 - 25.7 S 2.70 1.60 9.5 - 32.0 B 5.77 3.00 8.5 12.5 S 3.93 0.71 6.5 - 33.2 B 6.14 4.71 5.5 33.5 B 8.72 5.94 6.5 - 34.3 S 3.47 1.20 8.0 A-28 Appendix III. B. Physical/chemical characteristics and plant pigments tabulated by salinity for the special chemistry transect series. Cruise 2. (December, 1981) Total Depth Conduc- Water Ortho- Dissolved Total Salinity S/B tivity Temp. phosphate Phosphorus Phosphorus 0.0 S - - 0.07 - 6.2 0.0 S - - 0.20 - 4.4 0.0 S - - - 1.0 3.7 4.4 S 5.5 9.2 0.49 1.7 2.4 6.0 S 7.5 9.0 0.30 1.2 3.4 6.9 S 8.4 9.1 0.47 1.2 2.2 9.1 B 11.0 9.2 0.42 1.2 4.8 9.3 S 11.2 9.3 0.41 1.0 3.9 9.8 B 11.6 9.1 0.43 1.4 8.4 11.3 S 13.5 8.9 0.41 1.1 9.6 12.0 S 14.2 9.2 0.37 0.8 2.8 14.4 S 16.8 9.0 0.38 0.9 2.5 17.5 S 19.3 8.3 0.45 0.7 3.9 22.2 B 25.0 8.9 0.51 0.6 3.2 28.1 S 31.2 8.8 0.35 0.6 2.4 31.4 B 34.6 9.3 0.30 0.5 2.5 32.6' B 36.0 9.5 0.24 0.4 1.3 33.2 S 36.7 9.5 1.84 0.4 1.1 33.2 S 36.6 9.7 - 0.2 1.2 33.2 B 36.7 9.7 - 0.3 1.1 33.2 B 36.8 10.0 0.15 0.4 1.1 33.3 S 36.8 9.9 0.20 1.5 1.2 33.6 B 37.0 9.5 0.43 - 1.0 A-29 Appendix III. B. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 2. (December, 1981) Total Depth Nitrate- Dissolved Total Salinity S/B Ammonia Nitrite Nitrogen Nitrogen 0.0 S 6.88 11.73 - 159.4 0.0 S 1.67 6.01 - 107.8 .0.0 S 0.96 - 64.9 95.4 4.4 S 0.14 10.83 65.3 93.0 6.0 S 3.14 8.81 61.4 80.3 6.9 S 0.53 10.46 76.2 64.8 9.1 B 0.20 9.95 61.5 92.9 9.3 S 0.02 9.30 78.3 84.0 9.8 B 0.28 9.00 69.6 93.0 11.3 S 0.62 8.86 72.9 110.8 12.0 S 0.09 8.19 67.4 67.8 14.4 S 0.02 7.20 65.5 82.8 17.5 S 3.86 7.38 49.2 70.1 22.2 B - 6.85 53.3 71.9 28.1 S 0.15 5.65 70.0 76.8 31.4 B 1.24 2.68 70.6 66.6 32.6 B - 1.29 66.1 73.8 33.2 S 0.15 1.41 60.9 75.7 33.2 S 0.12 - 35.2 83.6 33.2 B 0.21 - 39.6 59.3 33.2 B 0.47 0.74 41.0 43.7/ 33.3 S - 0.78 66.3 50.1 33.6 B - 0.94 59.0 A-30 Appendix III. B. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 2. (December, 1981) Dissolved Total Depth Chloro- Phaeo- Organic Organic Salinity S/B phyll a pigments Carbon Carbon 0.0 S 7.39 13.44 13.6 20.6 0.0 S 3.07 3.40 - 18.2 0.0 S 1.64 1.71 12.1 9.4 4.4 S 3.93 1.96 7.9 10.3 6.0 S 5.77 4.39 10.3 10.8 6.9 S 3.56 1.75 8.8 9.1 9.1 B 4.05 5.65 9.7 10.9 9.3 S 5.16 4.77 8.8 11.5 9.8 B 6.63 9.53 9.1 17.3 11.3 S 6.39 10.70 9.7 16.3 12.0 S 3.07 3.51 8.8 10.3 14.4 S 3.44 2.68 7.6 8.5 17.5 S 4.42 5.16 7.3 10.0 22.2 B 3.81 4.62 6.7 8.8 28.1 S 3.81 3.12 7.0 8.8 31.4 B 4.42 3.78 8.8 6.1 32.6 B 4.30 2.63 6.7 5.8 33.2 S 4.67 2.03 6.2 5.5 33.2 S 4.30 2.86 6.8 5.6 33.2 B 4.30 2.98 5.4 6.1 33.2 B 4.55 3.08 7.0 6.9 33.3 S 4.18 3.44 6.8 5.8 33.6 B 3.69 2.32 5.7 5.8 A-31 I Appendix III. C. Physical/chemical characteristics and plant pigments tabulated by salinity for the special chemistry transect series. Cruise 3. (January, 1982) Total Depth Conduc- Water Ortho- Dissolved Total Salinity S/B tivity Temp. phosphate Phosphorus Phosphorus 0.0 S 0.0 5.8 - 0.9 2.0 0.0 S 0.0 5.2 0.51 0.7 1.1 0.0 S 0.0 4.7 2.44 - 2.1 0.0 B 0.0 4.9 0.96 - 1.5 2.1 S 2.5 5.9 0.50 1.1 2.0 5.6 S 6.4 6.1 0.35 1.1 1.6 11.6 B 12.7 5.8 0.26 0.6 6.5 17.5 S 19.2 6.7 0.22 0.7 1.6 22.5 B 23.8 6.3 0.27 0.3 2.4 24.2 S 25.8 7.2 0.11 0.4 1.5 26.4 S 28.1 7.2 0.11 0.3 1.3 26.4 B 27.6 6.4 0.11 0.2 1.6 27.7 B 29.0 6.5 1.15 0.3 2.1 31.0 B 32.0 7.1 0.12 0.2 2.5 31.2 B 32.6 6.6 0.36 0.1 - 31.6 B 32.8 6.8 0.08 0.2 ' 2.4 I I A-32 Appendix III. C. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 3. (January,1982) Total Depth Nitrate- Dissolved Total Salinity S/B Ammonia Nitrite Nitrogen Nitrogen 0.0 S 0.88 18.17 86.1 82.6 0.0 S 0.29 23.26 71.4 91.2 0.0 S 0.15 27.66 77.3 85.4 0.0 B 0.51 29.03 97.7 85.3 2.1 S 0.60 14.99 74.5 73.9 5.6 S 4.21 18.51 64.4 71.5 11.6 B 0.02 9.44 68.9 109.9 17.5 S 0.10 13.54 70.7 61.9 22.5 B - 6.98 73.0 63.1 24.2 S 0.22 5.83 92.0 53.0 26.4 S 0.66 4.16 64.6 70.4 26.4 B 1.56 4.20 54.7 51.0 27.7 B 0.77 3.49 77.7 55.0 31.0 B 4.94 2.09 56.8 56.4 31.2 B - 0.93 57.9 31.6 B 0.34 0.66 50.2 51.5 A-33 Appendix III. C. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 3. (January, 1982) Dissolved Total Depth Chloro- Phaeo- Organic Organic Salinity S/B phyll a pigments Carbon Carbon 0.0 S 1.20 1.33 10.6 10.3 0.0 S 1.88 3.65 10.0 15.7 0.0 S 1.06 1.07 10.3 10.6 0.0 B 0.98 1.17 4.9 10.6 2.1 S 1.40 1.77 11.7 11.4 5.6 S 7.00 5.35 12.6 12.6 11.6 B 9.14 10.03 7.3 14.9 17.5 S 2.99 1.95 8.0 10.0 22.5 B 7.98 5.64 5.4 11.1 24.2 S 7.99 3.10 6.0 6.0 26.4 S 5.65 2.32 5.4 5.1 26.4 B 8.23 4.12 4.8 7.7 27.7 B 10.55 5.98 6.3 8.0 31.0 B 2.32 5.46 9.4 5.5 31.2 B 9.15 7.06 5.5 8.5 31.6 B 9.15 6.72 4.0 7.7 A-34 Appendix III. D. Physical/chemical characteristics and plant pigments tabulated by salinity for the special chemistry transect series. Cruise 4. (March, 1982) Total Depth Conduc- Water Ortho- Dissolved Total Salinity S/B tivity Temp. phosphate Phosphorus Phosphorus 0.0 S 0.0 16.9 1.02 - 0.5 0.0 S 0.0 16.1 1.52 - 0.2 1.0 S 0.5 15.3 0.89 1.4 3.5 2.0 S 1.1 16.2 0.89 1.1 2.4 5.5 S 7.9 15.4 0.83 1.0 2.0 8.0 S 13.8 15.9 0.93 0.6 1.7 10.8 B 12.0 15.9 1.01 1.0 - 15.5 S 22.9 15.0 0.50 0.4 0.8 20.0 S 28.4 14.6 0.54 0.4 - 21.6 B 29.2 14.6 0.51 3.2 1.8 29.0 B 38.4 14.2 0.26 0.2 0.7 29.0 B 37.7 14.2 0.33 0.3 0.6 29.1 B 37.0 14.3 0.37 0.2 0.6 30.8 B 40.4 14.0 0.42 0.1 0.8 32.0 S 40.3 13.9 0.45 0.1 0.9 32.0 S 39.7 14.1 0.42 - 0.7 32.0 B 40.3 14.2 0.15 0.2 0.2 32.1 B 40.4 14.2 0.65 - 0.7 A-35 Appendix III. D. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 4. (March, 1982) Total Depth Nitrate- Dissolved Total Salinity S/B Ammonia Nitrite Nitrogen Nitrogen 0.0 S 6.40 15.57 65.1 131.3 0.0 S 5.10 23.85 - 98.0 1.0 S 0.80 27.67 54.9 88.3 2.0 S 3.20 25.23 62.1 80.1 5.5 S 3.30 22.28 52.9 73.1 8.0 S 0.40 22.78 42.5 61.6 10.8 B 3.90 19.52 44.5 - 15.5 S 7.40 15.44 39.5 55.4 20.0 S 2.40 12.53 40.9 65.7 21.6 B 0.40 11.79 33.6 106.2 29.0 B 3.50 2.18 60.8 46.7 29.0 B 1.00 3.15 34.7 34.0 29.1 B 5.20 4.39 25.3 37.7 30.8 B 3.10 0.49 36.4 50.7 32.0 S 1.20 1.78 20.9 42.4 32.0 S 3.50 1.58 24.0 50.6 32.0 B 2.50 1.07 22.4 41.4 32.1 B 1.60 0.76 20.2 60.1 A-36 Appendix III. D. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 4. (March, 1982) Dissolved Total Depth Chloro- Phaeo- Organic Organic Salinity S/B phyll a pigments Carbon Carbon 0.0 S 1.69 2.12 13.6 13.9 0.0 S 1.16 2.11 14.4 12.8 1.0 S 3.69 4.86 12.9 17.2 2.0 S 1.93 2.06 13.3 16.1 5.5 S 2.22 1.68 11.9 11.1 8.0 S 4.67 2.03 11.1 11.9 10.8 B 4.57 28.49 9.7 - 15.5 S 1.98 1.38 8.3 10.0 20.0 S 2.07 1.60 6.9 10.0 21.6 B 2.95 4.67 7.2 11.4 29.0 B 2.51 1.89 4.7 6.9 29.0 B 2.36 1.76 5.0 5.6 29.1 B 2.60 2.02 5.3 6.1 30.8 B 2.70 2.42 4.2 9.7 32.0 S 2.94 2.22 3.9 21.9 32.0 S 2.80 2.19 5.0 - 32.0 B 2.02 1.87 3.9 10.0 32.1 B 2.51 2.30 4.4 7.3 A-37 I Appendix III. E. Physical/chemical characteristics and plant pigments tabulated by salinity for the special chemistry transect series. Cruise 5. (May, 1982) Total Depth Conduc- Water Ortho- Dissolved Total Salinity S/B tivity Temp. phosphate Phosphorus Phosphorus 0.0 S 0.0 - 1.18 2.4 3.3 1.0 S 1.8 26.5 0.67 2.1 2.8 2.2 S 4.0 26.8 0.57 1.9 2.8 2.6 S 4.6 26.5 0.58 1.7 2.9 3.2 S 5.7 26.7 0.52 1.7 2.4 5.1 B 8.8 26.0 0.50 1.5 3.5 -5.8 S 10.1 26.5 0.44 1.5 2.4 7.1 S 12.3 26.5 0.49 1.5 2.1 7.5 B 12.8 26.0 0.53 1.4 2.5 8.1 B 13.6 26.1 0.80 1.3 2.1 10.8 S 18.2 26.4 0.37 1.0 3.7 12.7 S 21.1 26.2 0.28 0.9 2.0 16.7 S 27.4 26.2 0.28 0.8 2.1 21.3 B 33.9 25.4 0.48 1.5 2.2 22.3 B 35.3 25.5 0.34 0.6 3.8 23.2 B 36.5 25.6 0.37 0.8 2.8 23.7 S 37.8 25.8 0.38 0.7 1.3 25.3 B 39.5 25.3 0.36 0.3 1.4 29.5 S 45.6 25.1 0.54 0.6 1.1 31.7 B 47.9 25.4 0.24 0.6 1.7 32.5 S 50.0 25.7 0.23 1.0 1.8 33.5 B 51.5 25.7 0.19 0.5 1.2 A-38 Appendix III. E. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 5. (May, 1982) Total Depth Nitrate- Dissolved Total Salinity S/B Ammonia Nitrite Nitrogen Nitrogen 0.0 S 0.23 8.00 63.5 68.0 1.0 S 0.25 16.13 51.9 58.6 2.2 S 1.41 15.31 51.7 59.4 2.6 S 0.19 11.83 56.7 64.1 3.2 S 0.20 13.45 51.5 55.9 5.1 B 0.16 13.13 50.5 66.8 5.8 S 0.20 13.64 49.1 58.1 7.1 S 0.29 12.63 48.8 53.6 7.5 B 0.13 12.51 48.1 56.5 8.1 B 0.14 12.27 49.2 53.3 10.8 S 0.21 11.05 41.5 66.2 12.7 S 0.21 10.40 38.8 50.8 16.7 S 2.51 8.29 31.7 48.6 21.3 B 0.13 9.17 37.6 48.4 22.3 B 0.16 5.91 32.0 62.3 23.2 B 0.15 5.36 30.9 50.4 23.7 S 0.08 5.36 27.0 36.2 25.3 B 0.40 4.30 24.2 34.3 29.5 S 0.54 3.12 21.8 32.9 31.7 B 0.45 1.44 23.1 36.2 32.46 S 0.49 1.24 22.3 28.3 33.5 B 0.55 0.38 14.9 31.8 A-39 Appendix III. E. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 5. (May, 1982) Dissolved Total Depth Chloro- Phaeo- Organic Organic Salinity S/B phyll a pigments Carbon Carbon 0.0 S 0.59 1.22 17.4 19.1 1.0 S 2.65 3.15 10.3 10.9 2.2 S 1.64 1.58 11.1 11.1 2.6 S 2.95 4.44 14.3 13.7 3.2 S 4.30 3.67 11.4 11.4 5.1 B 2.83 5.95 11.7 13.7 5.8 S 5.77 3.70 11.2 12.4 7.1 S 3.93 3.34 10.9 11.1 7.5 B 3.07 4.20 10.9 12.4 8.1 B 2.46 3.48 11.1 11.1 10.8 S 29.20 8.50 10.0 11.2 12.7 S 8.85 5.24 9.4 10.0 16.7 S 6.51 4.46 9.4 9.7 21.3 B 3.81 4.51 8.5 10.3 22.3 B 3.93 7.96 7.1 12.4 23.2 B 2.70 6.54 6.5 9.1 23.7 S 5.16 2.92 6.5 7.4 25.3 B 3.19 4.54 5.6 7.1 29.5 S 5.04 2.12 5.3 5.6 31.7 B 3.19 3.73 6.5 5.9 32.5 S 2.70 1.29 7.4 5.1 33.5 B 2.58 4.58 3.8 5.7 A-40 Appendix III. F. Physical/chemical characteristics and plant pigments tabulated by salinity for the special chemistry transect series. Cruise 6. (July, 1982) Total Depth Conduc- Water Ortho- Dissolved Total Salinity S/B tivity Temp. phosphate Phosphorus Phosphorus 0.0 S 0.0 28.4 0.58 2.8 3.5 1.7 S 3.3 28.1 0.81 2.1 3.4 2.8 S 5.5 28.1 0.77 1.5 2.7 5.1 S 9.5 29.2 0.23 1.3 2.9 9.5 S 16.7 28.5 0.34 1.0 2.0 15.0 B 25.4 27.7 0.22 0.7 0.0 15.4 S 26.1 27.5 0.42 0.6 1.7 16.3 B 27.5 27.4 0.51 2.0 3.8 17.3 B 28.5 27.6 0.38 0.5 4.1 19.6 B 32.6 27.2 0.82 0.3 2.8 23.6 S 38.1 27.9 0.41 0.3 1.5 28.8 S 45.7 27.2 0.86 0.3 1.4 30.1 B 47.7 26.4 0.26 0.0 2.1 32.3 B 50.2 25.9 0.22 0.0 2.1 32.8 S 51.6 27.3 0.24 0.2 1.9 32.9 B 51.6 27.3 0.21 0.0 1.9 A-41 Appendix III. F. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 6. (July, 1982) Total Depth Nitrate- Dissolved Total Salinity S/B Ammonia Nitrite Nitrogen Nitrogen 0.0 S 1.21 22.41 62.4 70.7 1.7 S 0.62 20.19 54.5 62.6 2.8 S 1.32 20.27 54.2 60.3 5.1 S 4.73 19.87 51.5 63.9 9.5 S 0.70 18.15 48.4 55.9 15.0 B 1.36 14.10 40.1 0.0 15.4 S 0.72 13.24 35.5 45.9 16.3 B 1.18 19.68 50.0 60.4 17.3 B 0.88 13.39 35.4 60.5 19.6 B 0.95 10.37 29.4 51.9 23.6 S 1.43 10.31 29.4 40.8 28.8 S 1.55 10.07 31.7 40.4 30.1 B 0.47 3.44 18.6 39.1 32.3 B 0.35 1.82 14.5 41.2 32.8 S 0.40 1.40 14.8 33.0 32.9 B 0.57 1.18 11.5 37.9 A-42 Appendix III. F. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 6. (July, 1982) Dissolved Total Depth Chloro- Phaeo- Organic Organic Salinity S/B phyll a pigments Carbon Carbon 0.0 S - - 11.4 10.8 1.7 S 4.40 6.87 10.6 11.0 2.8 S 7.16 4.49 10.3 12.7 5.1 S 7.98 6.04 9.4 11.9 9.5 S 8.26 5.77 9.2 10.4 15.0 B 23.54 68.80 8.1 30.0 15.4 S 8.81 4.22 7.5 9.6 16.3 B 8.95 4.83 9.5 13.3 17.3 B 9.34 9.13 7.1 10.6 19.6 B 8.40 7.01 6.3 9.3 23.6 S 7.98 4.67 6.4 6.4 28.8 S 4.40 10.50 8.7 8.1 30.1 B 11.36 9.69 3.8 5.8 32.3 B 14.61 14.57 3.5 6.7 32.8 S 8.40 7.51 3.8 6.7 32.9 B 9.74 9.83 3.5 6.6 A-43 Appendix III. G. Physical/chemical characteristics and plant pigments tabulated by salinity for the special chemistry j transect series. Cruise 7. (September, 1982) Total Depth Conduc- Water Ortho- Dissolved Total Salinity S/B tivity Temp. phosphate Phosphorus Phosphorus 0.0 S - - 0.62 1.6 0.0 2.3 S 4.1 26.6 0.57 0.9 2.2 3.3 S 6.0 26.8 0.57 0.8 1.4 5.0 S 8.7 26.2 0.38 0.5 2.1 5.1 S 9.0 26.5 0.50 1.0 1.2 7.3 S 12.5 26.0 0.38 0.6 0.9 8.5 B 14.3 26.3 0.38 0.6 2.7 1 12.0 S 20.1 26.1 0.43 0.3 0.7 12.6 S 21.1 26.7 0.37 - 1.0 1 13.9 B 22.9 25.8 0.44 0.5 1.2 15.3 B 24.9 26.0 0.41 0.2 1.0 1 15.9 S 25.9 25.5 0.41 0.0 0.7 17.7 B 28.4 25.6 0.38 1.6 8.7 21.9 B 34.9 25.8 0.47 0.4 2.0 | 23.3 B 26.7 25.3 0.44 0.2 2.3 24.6 S 38.9 25.7 0.45 1.0 0.6 26.3 B 40.8 25.3 0.45 1.2 1.2 28.9 S 45.2 25.7 0.38 0.3 0.6 U 32.9 B 50.5 25.7 0.35 0.1 1.3 33.3 S 51.2 25.6 0.40 0.1 0.7 35.0 B 53.4 25.4 0.35 0.0 1.4 A-44 Appendix III. G. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 7. (September, 1982) Total Depth Nitrate- Dissolved Total Salinity S/B Ammonia Nitrite Nitrogen Nitrogen 0.0 S 5.41 2.98 44.1 10.2 2.3 S 1.44 0.50 39.4 48.2 3.3 S 1.31 - 40.7 54.5 5.0 S 3.87 2.21 39.3 60.0 5.1 S 2.02 4.64 44.3 48.2 7.3 S 2.59 1.77 37.5 47.0 8.5 B 2.88 0.19 40.5 55.1 12.0 S 1.69 1.06 36.8 44.4 12.6 S 1.45 4.94 35.3 36.5 13.9 B 2.48 4.38 40.4 63.2 15.3 B 3.36 3.40 31.8 58.9 15.9 S 1.59 3.12 26.0 42.3 17.7 B 3.08 2.45 34.1 82.1 21.9 B 3.03 0.85 26.1 46.1 23.3 B 2.61 0.18 25.8 53.7 24.6 S 3.08 4.89 33.6 27.2 26.3 B 2.97 4.35 27.5 34.6 28.9 S 2.36 2.49 21.1 31.6 32.9 B 1.92 1.40 12.8 32.4 33.3 S 1.53 1.21 15.9 22.9 35.0 B 1.43 0.55 11.4 30.3 A-45 Appendix III. G. Physical/chemical characteristics and plant pigments (continued) tabulated by salinity for the special chemistry transect series. Cruise 7. (September, 1982) Dissolved Total Depth Chloro- Phaeo- Organic Organic Salinity S/B phyll a pigments Carbon Carbon 0.0 S 3.72 3.48 6.5 6.9 2.3 S 11.77 5.22 6.2 6.8 3.3 S 19.28 5.46 6.5 7.1 5.0 S 5.78 7.06 8.8 10.0 5.1 S 10.32 4.21 6.0 6.5 7.3 S 13.59 5.79 6.9 7.1 8.5 B 7.91 5.80 6.2 7.5 12.0 S 16.64 4.78 6.3 6.2 12.6 S 22.12 5.03 6.2 7.4 13.9 B 14.00 10.01 5.8 8.2 15.3 B 11.77 9.10 5.7 8.5 15.9 S 20.70 5.52 5.5 6.2 17.7 B 8.88 4.96 6.0 6.3 21.9 B 9.95 11.11 5.1 7.5 23.3 B 4.13 13.40 4.8 8.9 24.6 S 4.41 2.92 4.3 5.2 26.3 B 4.34 5.93 3.8 5.4 28.9 S 3.51 4.81 3.4 4.6 32.9 B 4.34 2.74 2.8 4.2 33.3 S 3.10 5.05 2.8 3.5 35.0 B 6.06 7.66 2.3 4.5 A-46 Appendix IV. A. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Total Zooplankton Station Date Sep Nov Jan Mar May Jul Sep All PR 4548 1386 2212 2618 10146 15278 6070 6036 SR 12210 3344 934 6958 17462 2270 23026 9458 PD 9098 2367 307 1516 32310 2938 11245 8540 WR 3240 1654 122 998 34463 1834 4592 6700 BI 26625 5360 224 2080 20948 9322 14452 11287 TA 21344 8090 364 848 46268 2646 3400 11852 PS 8702 8690 665 440 30658 5177 17877 10316 TC 11707 10852 476 339 28499 16106 21196 12739 EP 18409 4866 1948 98 7896 1900 18692 7687 MB 19082 8818 374 860 24456 10330 21947 12267 SB 10294 7724 1340 3176 31530 11524 9692 10754 ALL 13205 5741 815 1812 25876 7211 13835 9785 A-47 Appendix IV. B. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Total Copepods Station Date Sep Nov Jan Mar May Jul Sep All PR 3899 136 896 2454 7705 11706 1827 4089 SR 10733 1996 468 6646 12949 1064 1524 5054 PD 7904 1539 184 1338 27198 2426 7151 6820 WR 2983 342 60 604 33616 1708 1758 5867 BI 23723 4558 133 1892 15731 8300 6418 8679 TA 20494 7496 256 828 43950 1808 3316 11164 PS 8037 8298 408 419 30062 4978 17498 9957 TC 9242 6038 242 280 24378 8158 15396 9105 EP 15444 1016 1851 66 6440 1690 7942 4921 MB 16876 5758 226 560 15754 6933 18526 9233 SB 5832 5008 1082 2881 20416 6260 6823 6900 ALL 11379 3835 528 1633 21654 5248 8016 7435 A-48 Appendix IV. C. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the-average abundance for all stations within a specific sampling period are also presented. Acartia tonsa Station Date Sep Nov Jan Mar May Jul Sep All PR 793 26 0 0 4430 157 658 866 SR 3056 96 0 0 5292 296 318 1294 PD 2091 794 0 0 15642 44 3036 3087 WR 830 142 0 0 13238 2 934 2164 BI 6612 1670 1 3 8598 3112 1840 3120 TA 6566 2208 0 12 18142 772 1186 .5555 PS 2310 2004 0 14 10648 2966 10238 4026 TC 1410 1082 8 2 10242 4027 5898 3239 EP 6587 149 434 4 3840 154 4332 2214 MB 5416 391 4 6 4994 2230 5926 2710 SB 772 96 8 56 947 1924 1073 696 ALL 3313 787 41 9 9638 1426 3222 2634 A-49 Appendix IV. D. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Acartia copepodids Station Date Sep Nov Jan Mar May Jul Sep All PR 2922 90 0 0 2210 156, 1058 920 SR 7222 1514 0 0 7278 108 1085 2458 PD 5600 690 0 0 11090 26 4010 3059 WR 2101 98 0 0 2170 0 809 740 BI 16015 2420 0 0 5958 3564 4320 4611 TA 13082 4600 0 28 15280 473 2116 5083 PS 4568 5030 0 16 17962 1913 7139 5233 TC 6716 3550 0 16 10591 3132 8259 4609 EP 7933 82 22 8 1226 283 3450 1858 MB 8918 562 3 10 5338 3347 10436 4088 SB 441 280 22 122 637 1876 1919 757 ALL 6865 1720 4 18 7249 1352 4055 3038 A-50 Appendix IV. E. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Eurytemora affinis Station Date Sep Nov Jan Mar May Jul Sep All PR 0 0 182 2027 598 8954 0 1680 SR 0 0 13 6352 0 104 0 924 PD 0 0 1 1086 98 411 0 228 WR 0 0 0 366 15999 1233 0 2514 BI 0 0 25 1505 0 11 0 220 TA 0 0 136 568 0 453 0 165 PS 0 0 232 166 0 51 0 64 TC 0 0 44 52 0 18 0 16 EP 0 0 60 20 0 221 0 43 MB 0 0 84 6 0 0 0 13 SB 0 0 90 0 0 0 10 14 ALL 0 0 79 1104 1518 1041 1 535 A-51 Appendix IV. F. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Paracalanus crassirostris Station Date Sep Nov Jan Mar May Jul Sep All PR 6 0 0 0 11 0 8 4 SR 81 2 0 0 0 0 0 12 PD 17 2 0 0 26 0 0 6 WR 10 0 0 0 0 0 0 1 BI 180 122 0 0 530 26 100 137 TA 264 27 0 1 66 0 0 51 PS 630 768 0 16 1200 14 80 387 TC 218 408 1 38 1970 58 332 432 EP 165 384 74 0 967 0 34 232 MB 1352 2146 4 74 2594 110 730 1000 SB 3368 1858 22 243 13086 1066 2090 3105 ALL 572 519 9 34 1859 116 307 488 A-52 Appendix IV. G. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. PseudodiaDtomus coronatus Station Date Sep Nov Jan Mar May Jul Sep All PR 4 2 0 0 0 0 32 5 SR 86 0 0 0 16 0 0 14 PD 27 0 0 0 0 0 0 4 WR 10 2 0 0 0 0 0 2 BI 307 115 0 0 279 0 0 100 TA 157 28 0 0 129 0 0 45 PS 43 37 0 0 0 0 0 11 TC 291 125 0 0 872 152 225 238 EP 550 4 0 0 207 0 57 117 MB 795 50 0 2 172 272 465 246 SB 141 66 2 16 142 582 326 182 ALL 216 39 0 2 165 91 I00 88 A-53 Appendix IV. H. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Euterpina acutifrons Station Date Sep Nov Jan Mar May Jul Sep All PR 0 0 0 0 0 0 8 1 SR 0 0 0 0 0 0 0 0 PD 0 0 0 0 0 0 13 2 WR 0 0 0 0 0 0 0 0 BI 0 16 0 0 37 0 43 14 TA 0 0 0 0 70 0 0 10 PS 0 0 0 0 78 0 20 14 TC 11 127 0 0 385 0 216 106 EP 0 44 9 0 96 0 0 21 MB 0 244 1 1 1264 0 506 288 SB 156 107 2 0 2456 31 292 435 ALL 15 49 1 0 399 3 100 81 A-54 Appendix IV. I. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Oithona colcarva Station Date Sep Nov Jan Mar May Jul Sep All PR 14 0 0 0 0 0 0 1 SR 86 0 0 0 0 0 0 12 PD 72 0 0 78 0 4 14 13 WR 0 0 0 0 0 0 0 0 BI 280 38 0 4 37 26 28 59 TA 134 40 0 4 94 3 0 39 PS 282 90 0 38 78 4 20 73 TC 288 209 2 125 97 64 100 126 EP 104 153 6 4 18 2 40 47 MB 214 978 20 236 192 66 182 270 SB 627 684 110 1316 826 368 354 612 ALL 191 199 13 157 122 49 67 114 A-55 Appendix IV. J. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Halicvclops spp. Station Date Sep Nov Jan Mar May Jul Sep All PR 0 0 72 148 412 2300 0 419 SR 0 0 39 82 136 426 0 98 PD 0 0 2 70 220 1041 0 190 WR 0 0 1 85 2062 454 0 372 BI 0 0 2 30 0 1036 0 152 TA 0 0 4 0 0 39 5 7 PS 0 0 30 0 0 0 0 4 TC 0 0 6 0 0 485 32 75 EP 0 0 5 1 0 454 0 66 MB 0 0 4 1 0 10 0 2 SB 0 0 12 0 0 0 0 2 ALL 0 0 16 38 257 568 3 126 A-56 Appendix IV. K. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Barnacle nauplii Station Date Sep Nov Jan Mar May Jul Sep All PR 336 855 70 0 344 0 2816 632 SR 1280 444 0 0 610 2 19040 3054 PD 934 56 0 0 670 0 2986 664 WR 164 17 0 0 34 0 1042 180 BI 2801 434 0 0 370 92 6918 1516 TA 540 164' 0 0 488 52 68 187 PS 514 312 0 12 174 12 338 195 TC 2074 4514 2 16 170 590 4480 1692 EP 2174 3362 14 1 753 35 9295 2233 MB 1421 1848 2 48 4972 1173 1578 1577 SB 2116 1882 2 34 7214 2666 822 2105 ALL 1305 1262 8 10 1436 420 4490 1276 A-57 Appendix IV. L. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Barnacle cyprids Station Date Sep Nov Jan Mar May Jul Sep All PR 42 3 35 0 256 0 266 86 SR 0 16 12 0 306 0 1703 291 PD 8 19 0 0 2092 4 132 322 WR 0 25 0 0 457 0 25 72 BI 25 87 0 0 1430 88 500 304 TA 43 168 4 3 1093 24 0 191 PS 7 18 6 2 154 30 20 34 TC 28 25 39 18 2248 491 446 471 EP 45 14 24 1 294 34 1126 220 MB 70 79 52 28 643 212 608 242 SB 34 54 90 10 830 538 64 231 ALL 28 46 24 6 891 129 444 221 A-58 Appendix IV. M. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Crab zoeae Station Date Sep Nov Jan Mar May Jul Sep All PR 0 0 0 0 898 3258 118 610 SR 0 0 0 0 3446 974 18 634 PD 0 0 0 0 293 451 13 108 WR 0 0 0 0 134 64 10 30 BI 0 0 0 0 3201 372 0 510 TA 23 0 0 0 266 88 0 54 PS 0 0 0 0 154 52 0 29 TC 10 0 0 0 1533 3530 21 728 EP 0 5 0 0 127 14 0 21 MB 0 0 0 0 2078 266 0 335 SB 12 0 0 0 294 238 10 79 ALL 4 1 0 0 1130 846 17 285 A-59 Appendix IV. N. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Polychaete larvae Station Date Sep Nov Jan Mar May Jul Sep All PR 128 198 0 0 90 140 16 82 SR 112 667 1 0 135 104 16 146 PD 208 296 1 0 1386 14 13 274 WR 76 79 0 0 188 2 5 50 BI 51 226 0 0 21 301 0 86 TA 156 172 0 0 470 662 0 208 PS 88 8 0 1 116 84 0 42 TC 199 188 1 2 0 672 62 160 EP 76 212 0 0 116 62 28 70 MB 536 776 0 32 364 108 162 283 SB 408 512 4 125 570 146 214 283 ALL 185 303 1 14 314 209 46 153 A-60 Appendix IV. O. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Gastropod veligers Station Date Sep Nov Jan Mar May Jul Sep All PR 128 0 0 42 809 35 337 193 SR 40 0 0 80 16 0 96 33 PD 25 0 0 114 647 0 40 118 WR 0 2 0 78 34 12 5 19 BI 0 0 0 0 18 44 14 11 TA 0 9 0 0 0 0 0 1 PS 0 0 0 0 0 9 0 1 TC 11 0 0 1 0 2472 574 437 EP 520 0 0 0 84 40 138 112 MB 0 76 0 2 108 964 973 303 SB 12 12 0 31 369 1178 502 301 ALL 67 9 0 32 190 432 244 139 A-61 Appendix IV. P. Zooplankton abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Bivalve larvae Station Date Sep Nov Jan Mar May Jul Sep All PR 0 0 0 0 0 0 0 0 SR 0 0 0 0 0 0 0 0 PD 0 0 0 0 0 4 0 1 WR 0 0 0 2 0 6 0 1 BI 0 0 0 0 18 0 0 3 TA 0 0 0 0 0 0 2 0 PS 0 0 0 0 0 4 0 1 TC 38 0 1 0 122 18 0 26 EP 0 0 18 0 64 0 0 12 MB 0 40 10 2 129 80 61 46 SB 59 18 28 40 466 248 33 127 ALL 9 5 5 4 73 33 9 20 A-62 Appendix V. A. Zooplankton abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, depth, and month. The annual average for each station and depth is also presented. Total Copepods Station Sep Nov Jan Mar May Jul Sep All US surf. 10452 9008 72 1884 7566 1562 3182 4818 bot. 19572 21336 69 6776 40654 4086 7731 14318 MS surf. 11298 2406 211 187 23033 3088 6360 6655 bot. 20430 5342 372 2260 14983 13170 9875 9490 LSsurf. 8616 14652 6716 16579 13876 27784 7344 13652 bot. 31469 12670 10464 5656 12040 25401 7906 15086 Total Zooplankton Station Sep Nov Jan Mar May Jul Sep All US surf. 11538 10196 176 2892 11176 3832 6773 6655 bot. 29874 22906 152 7062 41782 6536 23461 18825 MS surf. 12964 3640 688 236 24708 6353 19902 9784 bot. 26428 6730 626 2494 16100 16674 14572 11947 LSsurf. 13040 21165 7239 18122 19259 44344 16183 19908 bot. 44352 17949 11967 6105 14860 37746 13226 20887 A-63 Appendix V. B. Zooplankton abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, depth, and month. The annual average for each station and depth is also presented. Acartia tonsa Station Sep Nov Jan Mar May Jul Sep All US surf. 2160 2616 0 3 2704 838 942 1313 bot. 5203 10276 0 12 21705 2343 3222 6109 MS, surf. 3989 1092 12 4 12778 604 2656 3020 bot. 9220 2556 12 42 9890 3885 2482 4012 LS surf. 1139 96 840 60 585 1972 942 805 bot. 7996 334 1229 72 981 3556 1556 2246 Acartia copepodids Station Sep Nov Jan Mar May Jul Sep All US us surf. 7774 5514 0 0 4388 556 2158 2913 bot. 12294 9544 0 0 18658 1482 3622 6514 MS surf. 5590 818 6 3 8480 1996 1184 2582 bot. 4601 1498 3 20 2698 4820 2734 2339 LS surf. 668 384 244 66 456 6390 1940 1450 bot. 2376 686 352 17 322 4892 1792 1491 A-64 Appendix V. C. Zooplankton abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, depth, and month. The annual average for each station and depth is also presented. Eurytemora affinis Station Sep Nov Jan Mar May Jul Sep All US surf. 0 0 0 584 70 16 0 96 bot. 0 0 2 3744 42 54 0 549 MS surf. 0 0 0 0 0 0 0 0 bot. 0 0 44 34 0 0 0 11 LS surf. 0 0 0 0 0 0 0 0 bot. 0 0 0 0 0 0 0 0 Paracalanus crassirostris Station Sep Nov Jan Mar May Jul Sep All US surf. 8 18 0 0 0 0 0 4 bot. 336 16 0 0 42 6 98 71 MS surf. 902 296 10 38 934 220 1535 562 bot. 3604 722 38 235 1664 1310 2060 1376 LS surf. 3471 6896 1398 651 10090 9384 2566 4922 bot. 14368 6118 2747 448 7494 9072 2889 6162 A-65 Appendix V. D. Zooplankton abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, depth, and month. The annual average for each station and depth is also presented. PseudodiaDtomus coronatus Station Sep Nov Jan Mar May Jul Sep All US surf. 94 0 0 0 0 0 0 13 bot. 332 140 0 0 42 0 492 144 MS surf. 224 55 8 1 304 101 182 125 bot. 548 48 0 6 352 828 494 325 LS surf. 47 55 0 16 466 '134 72 113 bot. 200 106 0 22 983 369 78 251 Euterpina acutifrons Station Sep Nov Jan Mar May Jul Sep All US surf. 0 0 1 0 0 0 0 1 bot. 0 16 0 0 42 0 98 22 MS surf. 16 46 4 0 224 0 433 103 bot. 0 14 0 0 132 51 1750 278 LS surf. 236 1298 27 0 690 493 350 236 bot. 160 722 26 0 636 480 248 160 A-66 Appendix V. E. Zooplankton abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, depth, and month. The annual average for each station and depth is also presented. Oithona colcarva Station Sep Nov Jan Mar May Jul Sep All US surf. 16 0 0 2 0 5 0 3 bot. 358 0 0 9 0 8 172 78 MS surf. 262 46 32 92 29 28 202 99 bot. 1274 176 40 917 54 1404 136 571 LS surf. 916 4138 470 13211 555 1988 230 3073 bot. 2307 3412 838 783 314 2021 236 1416 Halicvcloos spp. Station Sep Nov Jan Mar May Jul Sep All US surf. 0 0 4 192 362 142 0 100 bot. 0 0 4 238 84 100 0 61 MS surf. 0 0 3 0 0 0 0 <1 bot. 0 0 5 2 0 0 0 1 LS surf. 0 0 0 0 0 0 0 0 bot. 0 0 13 0 0 0 0 2 A-67 Appendix V. F. Zooplankton abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, depth, and month. The annual average for each station and depth is also presented. Barnacle nauplii Station Sep Nov Jan Mar May Jul Sep All US surf. 708 200 0 384 20 18 3030 623 bot. 1424 98 0 16 42 283 12701 2080 MS surf. 902 604 12 28 30 2494 12555 2376 bot. 871 352 14 12 10 214 308 254 LS surf. 1008 2126 0 265 79 7814 6758 2578 bot. 676 1714 26 0 98 735 3365 945 Barnacle cyprids Station Sep Nov Jan Mar May Jul Sep All US surf. 15 168 1 0 188 38 30 63 bot. 101 73 1 0 167 62 1084 212 MS surf. 33 262 6 4 623 262 488 240 bot. 186 295 10 10 820 788 448 210 LS surf. 30 18 0 0 1060 242 488 193 bot. 0 95 78 0 1208 45 448 210 A-68 Appendix V. G. Zooplankton abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, depth, and month. The annual average for each station and depth is also presented. Crab zoeae Station Sep Nov Jan Mar May Jul Sep All US surf. 0 0 0 0 3324 1040 0 624 bot. 0 0 0 0 418 1128 0 221 MS surf. 0 0 0 0 812 300 62 168 bot. 0 0 0 0 113 264 22 57 LS surf. 44 0 0 0 456 304 48 122 bot. 50 0 0 0 56 300 12 60 Polychaete larvae Station Sep Nov Jan Mar May Jul Sep All US surf. 246 743 1 0 30 21 0 149 bot. 634 1176 1 0 0 116 74 286 MS surf. 288 254 0 6 16 42 0 87 bot. 1796 370 6 44 0 871 174 466 LS surf. 1588 3604 280 576 458 4302 445 1607 bot. 7314 2166 732 64 408 3896 350 2133 A-69 Appendix V. H. Zooplankton abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, depth, and month. The annual average for each station and depth is also presented. Gastropod veligers Station Sep Nov Jan Mar May Jul Sep All US surf. 76 0 1 29 29 28 0 23 bot. 8144 0 1 49 292 508 1009 1429 MS surf. 207 4 2 1 48 14 126 57 bot. 1343 7 1 0 15 342 2675 626 LS surf. 40 94 0 184 54 44 48 66 bot. 374 60 26 14 80 78 34 95 Bivalve larvae Station Sep Nov Jan Mar May Jul Sep All US surf. 0 0 1 0 0 0 0 <1 bot. 0 42 4 0 0 6 24 11 MS surf. 12 4 3 0 14 23 43 14 bot. 83 0 16 10 24 152 101 55 LS surf. 164 78 198 144 312 501 256 236 bot. 621 35 496 106 219 1338 360 454 A-70 Appendix VI. A. Epibenthos abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Mysids Station Date Sep Nov Jan Mar May Jul Sep All PR 0.16 0 0 0 0.24 0.23 0.26 0.13 SR 1.13 0.01 0 0 9.21 16.32 42.31 9.85 PD 8.91 0.19 0 0 0.44 1.21 8.09 2.69 WR 18.24 0.23 0 0 0.44 0 1.74 2.95 BI 0.60 1.78 0.10 0.51 26.22 0.16 5.11 4.93 TA 1.27 1.23 0 0.64 15.05 0 25.90 6.30 PS 1.50 0.79 0 0.39 0.09 0.07 1.79 0.66 TC 1.68 4.32 0.26 4.68 6.77 3.90 0.37 3.14 EP 2.74 51.31 0.42 2.61 7.25 1.54 28.91 13.54 MB 0.59 0.20 1.66 38.12 1.53 0.16 0.16 6.06 SB 0.97 4.96 4.77 0.45 1.05 0.37 1.10 1.95 ALL 3.44 5.91 0.66 4.31 6.21 2.18 10.52 A-71 Appendix VI. B. Epibenthos abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Amphipods Station Date Sep Nov Jan Mar May Jul Sep All PR 0.06 0 3.38 0.46 0.01 15.09 0.17 2.74 SR 0.15 0 5.14 0.04 0.01 6.22 0.89 1.78 PD 1.27 0.15 0.32 11.41 0.08 33.42 134.81 25.92 WR 1.20 0.86 0 0.15 0.21 2.12 0.12 0.67 BI 0.68 0 0.25 8.40 0.09 1.23 3.93 2.08 TA 3.99 8.29 2.73 1.59 8.21 1.80 1.85 4.07 PS 3.55 1.99 17.78 0.07 0.16 0.09 0.29 3.42 TC 0.30 0.66 1.04 0.06 0.71 0.11 0 0.41 EP 0.05 0.62 0.02 0.87 2.26 0.71 0.41 0.71 MB 0.13 0.10 11.82 4.11 0 0.02 0.03 2.32 SB 0.04 0.78 1.21 0.24 0.07 0 0.16 0.36 ALL 1.04 1.22 3.97 2.49 1.07 5.53 12.97 A-72 Appendix VI. C. Epibenthos abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Decapod shrimp larvae Station Date Sep Nov Jan Mar May Jul Sep All PR 1.78 0 0 0 0.86 0.42 0.06 0.45 SR 0.53 0 0 0 3.91 15.46 0.69 2.94 PD 0.20 0 0 0 4.35 0.26 2.78 1.08 WR 5.98 0 0 0 0.03 0.01 2.58 1.23 BI 0.26 0 0 0 3.28 1.03 0.49 0.72 TA 0.14 0.02 0.03 0.02 1.41 1.46 0.43 0.50 PS 0 0.03 0 0.60 1.81 0.26 3.05 0.82 TC 0.06 0.01 0 0.13 2.57 3.89 0.49 1.02 EP 0.91 0 0 0.06 0.50 2.73 1.13 0.76 MB 0.38 0.02 0 0.06 3.41 0.51 0.72 0.73 SB 0.25 0.08 0 0.04 4.33 0.19 0.48 0.77 ALL 0.95 0.01 0.01 0.08 2.41 2.38 1.17 A-73 Appendix VI. D. Epibenthos abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Postlarval penaeid shrimp Station Date Sep Nov Jan Mar May Jul Sep All PR 0 0 0 0 0 0 0 0 0 SR 0 0 0 0 0 0 0.06 0.01 PD 0 0 0 0 0.01 0 0o14 0.02 WR 0 0 0 0 0 0 0.02 0.01 BI 0 0 0 0 0 0 0.03 0.01 TA 0.07 0.11 0 0 5.17 0.09 0.15 0.80 PS 0.08 0.02 0 0 0.01 0.02 0.27 0.06 TC 0 0 0 0 0 0.02 0.18 0.03 EP 0 0 0 0 0 0 0.12. 0.02 MB 0 0 0 0 0 0.02 0.10 0.02 SB 0' 0 0 0 0 0.05 0.18 0.03 ALL 0.01 0.01 0 0 0.47 0.02 0.11 A-74 Appendix VI. E. Epibenthos abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Crab megalopae Station Date Sep Nov Jan Mar May Jul Sep All PR 0.04 0 0 0 0 0.01 0.02 0.01 SR 0.07 0 0 0 0.02 0.12 0.34 0.08 PD 0.62 0.02 0 0 0.01 0.40 0.46 0.22 WR 0.72 0 0 0 0.01 0.14 0.27 0.16 BI 0.05 0.02 0 0 0.23 0 0.02 0.05 TA 0 0.05 0 0 0.05 0 0 0.01 PS 0 0.09 0 0 0 0 0 0.01 TC 0.15 0.23 0 0 0.20 0.33 0 0.13 EP 0.51 0.15 0 0 0.08 0 0.33 0.15 MB 0.03 0.01 0 0.08 0.31 0.02 0.01 0.07 SB 0.07 0.45 0 0 1.35 0.13 0.13 0.30 ALL 0.21 0.09 0 .0.01 0.21 0.10 0.14 A-75 Appendix VI. F. Epibenthos abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Fish eggs Station Date Sep Nov Jan Mar May Jul Sep All PR 0 0 0 0 0.02 0 0 0.01 SR 0 0 0 0 0.02 0 0 0.01 PD 0 0 0 0 0.16 0 0 0.02 WR 0 0 0 0 0.01 0 0 0.01 BI 0 0 0 0 14.16 0 0 2.02 TA 0 0 0 0 34.78 0.02 0 4.97 PS 0 0 0 0 1.93 0 0 0.28 TC 0 0 0 0 4.81 0 0 0.69 EP 0 0 0 0 3.62 0 0 0.52 MB 0.06 0 0 0.03 3.96 0 0 0.58 SB 0 0.01 0 0 1.00 0 0 0.14 ALL 0.01 0.01 0 0.01 5.86 0.01 0 A-76 Appendix VI. G. Epibenthos abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Fish larvae Station Date Sep Nov Jan Mar May Jul Sep All PR 0.01 0 0 0.57 0.28 0.20 0 0.15 SR 0.01 0 0 0.11 0.67 0.06 0.02 0.12 PD 0.03 0.14 0 0.02 2.37 0.22 0 0.40 WR 0.04 0.20 0 0.07 0.35 0.02 0.02 0.10 BI 0.02 0.04 0.03 0.70 0.70 0.07 0.03 0.23 TA 0.14 0.50 0.12 5.52 1.98 0.06 0.43 1.25 PS 0.12 0.20 0.27 6.83 3.06 0.65 0.17 1.61 TC 0.01 0.09 0.27 0.04 0.93 0.10 0.04 0.21 EP 0.01 0.02 0.04 0.05 0.79 0 0.04 0.14 MB 0 0.03 0.65 0.51 16.12 0.09 0.05 2.49 SB 0.01 0.81 0.37 0 2.32 0.12 0 0.52 ALL 0.04 0.18 0.16 1.31 2.69 0.14 0.07 A-77 I Appendix VI. H. Epibenthos abundance during extensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station and month. The annual average for each station and the average abundance for all stations within a specific sampling period are also presented. Total Organisms Station Date Sep Nov Jan Mar May Jul Sep All PR 2.18 0 3.41 1.03 1.51 16.00 0.54 3.52 SR 2.22 0.02 5.17 0.15 13.97 38.38 44.64 14.94 PD 11.38 0.53 0.32 11.43 7.46 35.51 147.30 30.56 WR 26.49 1.33 0 0.22 1.09 2.44 5.00 5.22 BI 1.88 1.89 0.40 9.61 44.87 2.61 9.93 10.17 TA 5.80 10.64 2.92. 7.78 66.96 3.49 28.95 18.08 PS 5.75 3.28 18.05 7.91 7.22 1.25 5.73 7.03 TC 2.70 5.53 1.57 5.11 16.14 8.41 1.12 5.80 EP 4.39 52.57 0.50 3.61 14.62 4.98 31.12 15.97 MB 1.47 0.46 14.55 43.05 28.67 0.95 1.41 12.94 SB 2.70 7.46 6.38 0.80 10.82 1.06 2.47 4.53 ALL 6.09 7.61 4.84 8.25 19.39 10.46 25.29 A-78 ............i.................................................... I Appendix VII. A. Epibenthos abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, month, and length of tow. Mean represents the average of the three tows. Abundance is expressed as number per cubic meter. I Mysids 3 Station Sep Nov Jan Mar May Jul Sep All Upper 3 min. 0.92 0.04 0.01 0.10 9.17 10.39 0.26 2.98 6 min. 1.46 0.14 0 0.05 7.85 6.84 - 2.72 9 min. 0.43 0 0 0.04 12.98 4.47 - 2.99 3 Mean 0.94 0.06 0.01 0.06 10.00 7.24 0.26 2.65 Middle 3 min. 0.20 0.04 0.59 1.04 96.17 0.03 0.13 14.03 6 min. 0.84 2.39 4.76 0.53 5.92 0.06 0.27 2.11 9 min. 1.89 2.95 4.57 14.30 10.45 0.23 0.06 4.92 I Mean 0.98 1.79 3.31 5.29 37.51 0.11 0.15 7.02 Lower 3 min. 0.76 0.16 1.65 2.47 0.02 0.05 4.33 1.35 | 6 min. 0.39 0.13 4.30 1.57 0.74 0 9.12 2.32 9 min. 0.25 0.08 6.34 10.11 2.13 0.01 0.10 2.72 I Mean 0.47 0.12 4.10 4.72 0.96 0.02 4.51 2.13 I | A-79 l Appendix VII. B. Epibenthos abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, month, and length of tow. Mean represents the average of the three tows. Abundance is expressed as number per cubic meter. Amphipods Station Sep Nov Jan Mar May Jul Sep All Upper 3 min. 0.16 0 0.33 0.03 0 9.37 0.06 1.42 6 min. 0.09 0 0.38 0.01 0.04 3.42 - 0.66 9 min. 0.07 0 0.55 0.01 0.01 2.81 - 0.58 Mean 0.10 0 0.42 0.18 0.02 5.20 0.06 0.85 Middle 3 min. 0.34 0.08 3.45 0.11 0.28 0.49 0.14 0.70 6 min. 0.85 0.07 0.82 0.15 0.12 0.02 0.05 0.30 9 min. 0.35 0.01 1.98 0.62 0.16 0.01 0.01 0.45 Mean 0.51 0.05 2.09 0.30 0.19 0.17 0.06 0.48 Lower 3 min. 0.52 0.43 0.08 2.00 0.40 0.24 0.24 0.56 6 min. 0.56 0.25 0.12 0.91 1.63 0.01 0.15 0.52 9 min. 0.22 0.40 0.85 1.27 2.50 0.03 0.11 0.77 Mean 0.44 0.36 0.35 1.40 1.50 0.09 0.17 0.62 A-80 Appendix VII. C. Epibenthos abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, month, and length of tow. Mean represents the average of the three tows. Abundance is expressed as number per cubic meter. Decapod shrimp larvae Station Sep Nov Jan Mar May Jul Sep All Upper 3 min. 1.05 0 0 0.02 4.00 4.33 0.54 1.42 6 min. 0.80 0 0 0.01 1.68 6.33 - 1.47 9 min. 0.26 0 0 0.01 1.32 8.31 - 1.65 Mean 0.70 0 0 0.01 2.34 6.32 0.53 1.41 Middle 3 min. 0.14 0 0 0.01 1.22 0.47 2.97 0.69 6 min. 1.15 0 0 0.03 7.17 0.24 1.97 1.51 9 min. 0.70 0.01 0 0.03 3.48 0.11 0.97 0.76 Mean 0.66 0.01 0 0.02 3.95 0.28 1.97 0.98 Lower 3 min. 0.47 0.01 0 0.01 0.89 1.29 7.23 1.41 6 min. 0.45 0.01 0 0.01 2.49 0.36 8.38 1.67 9 min. 0.29 0.01 0 0.03 3.01 0.25 3.62 1.03 Mean 0.40 0.01 0 0.01 2.13 0.64 6.41 1.37 A-81 Appendix VII. D. Epibenthos abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, month, and length of tow. Mean represents the average of the three tows. Abundance is expressed as number per cubic meter. Postlarval penaeid shrimp Station Sep Nov Jan Mar May Jul Sep All Upper 3 min. 0 0 0 0 0 0.01 0 0.01 6 min. 0 0 0 0 0 0 - 0 9 min. 0 0 0 0 0.01 0 - 0.01 Mean 0 0 0 0 0.01 0.01 0 0.01 Middle 3 min. 0 0 0 0 0 0.02 0.03 0.01 6 min. 0 0 0 0 0 0.01 0.01 0.01 9 min. 0 0 0 0 0 0.02 0 0.01 Mean 0 0 0 0 0 0.02 0.01 0.01 Lower 3 min. 0 0 0 0 0 0 0.11 0.02 6 min. 0 0 0 0 0 0 0.06 0.01 9 min. 0 0 0 0 0 0 0 0 Mean 0 0 0 0 0 0 0.06 0.01 A-82 Appendix VII. E. Epibenthos abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, month, and length of tow. Mean represents the average of the three tows. Abundance is expressed as number per cubic meter. Crab megalopae Station Sep Nov Jan Mar May Jul Sep All Upper 3 min. 0.14 0 0 0 0 0.05 0.12 0.04 6 min. 0.01 0 0 0 0.01 0.04 - 0.01 9 min. 0.03 0 0 0 0.02 0.07 - 0.02 Mean 0.06 0 0 0 0.01 0.05 0.12 0.03 Middle 3 min. 0 0 0 0 2.68 0.04 0.08 0.40 6 min. 0 0.02 0 0.01 0.85 0.02 0.18 0.15 9 min. 0.06 0.01 0 0.01 0.23 0.04 0.01 0.05 Mean 0.02 0.01 0 0.01 1.25 0.03 0.09 0.20 Lower 3 min. 0.23 0 0 0.03 0.16 0.03 0.24 0.10 6 min. 0.16 0.01 0 0.06 0.45 0.01 0.06 0.96 9 min. 0.14 0.02 0 0.02 0.60 0.01 0.01 0.54 Mean 0.18 0.01 0 0.04 0.40 0.02 0.11 1.32 A-83 Appendix VII. F. Epibenthos abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, month, and length of tow. Mean represents the average of the three tows. Abundance is expressed as number per cubic meter. Fish eggs Station Sep Nov Jan Mar May Jul Sep All Upper 3 min. 0 0 0 0 0.22 0.11 0 0.05 6 min. 0 0 0 0 0.06 0.08 - 0.02 9 min. 0 0 0 0 0.07 0.03 - 0.02 Mean 0 0 0 0 0.12 0.07 0 0.03 Middle 3 min. 0 0 0 0 5.95 0 0.01 0.99 6 min. 0 0 0 0 29.03 0.01 0.01 4.15 9 min. 0 0 0 0 20.42 0.01 0.01 2.92 Mean 0 0 0 0 18.47 0.01 0.01 2.64 Lower 3 min. 0 0.01 0 0 23.05 0 0 3.29 6 min. 0.02 0.01 0 0 10.55 0.02 0.01 1.52 9 min. 0.01 0.01 0 0 5.34 0.02 0.01 0.77 Mean 0.01 0.01 0 0 12.98 0.01 0.01 1.86 A-84 Appendix VII. G. Epibenthos abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, month, and length of tow. Mean represents the average of the three tows. Abundance is expressed as number per cubic meter. Fish larvae Station Sep Nov Jan Mar May Jul Sep All Upper 3 min. 0 0 0.02 0.08 0.47 0.16 0.01 0.11 6 min. 0.02 0 0.01 0.08 0.23 0.19 - 0.09 9 min. 0.02 0 0.01 0.05 0.62 0.06 - 0.13 Mean 0.01 0 0.01 0.07 0.44 0.14 0.01 0.10 Middle 3 min. 0.02 0.02 0.16 0.20 2.27 0.65 0.06 0.48 6 min. 0 0.02 0.89 0.01 5.30 0.17 0.03 0.92 9 min. 0.03 0.07 0.64 0.02 1.76 0.08 0.09 0.38 Mean 0.02 0.04 0.56 0.08 3.11 0.30 0.06 0.60 Lower 3 min. 0.09 0.03 0.19 0 12.77 0.74 0.08 1.99 6 min. 0.33 0.01 0.25 0.03 8.44 0.54 0.12 1.39 9 min. 0.01 0.01 0.15 0.03 3.71 0.91 0.40 0.75 Mean 0.14 0.02 0.20 0.02 8.30 0.73 0.20 1.37 A-85 Appendix VII. H. Epibenthos abundance during intensive series of cruises within Winyah Bay (1981 - 1982). Mean abundance is presented by station, month, and length of tow. Mean represents the average of the three tows. Abundance is expressed as number per cubic meter. Total Organisms Station Sep Nov Jan Mar May Jul Sep All Upper 3 min. 2.44 0.07 0.37 0.26 13.93 24.47 1.30 6.12 6 min. 2.70 0.16 0.41 O.17 1 9.94 16.96 - 5.06 9 min. 1.06 0.02 0.57 0.12 15.09 15.79 - 5.44 Mean 2.06 0.08 0.45 0.19 12.99 19.08 1.30 5.16 Middle 3 min. 0.85 0.39 4.45 1.73 108.91 2.55 3.78 17.52 6 min. 3.19 2.65 6.59 0.89 48.89 0.82 3.23 9.47 9 min. 3.16 3.21 7.41 15.28 36.75 0.69 3.33 9.98 Mean 2.40 2.08 6.13 5.97 64.85 1.36 3.45 12.32 Lower 3 min. 4.00 1.40 1.96 5.98 37.95 5.79 15.65 10.39 6 min. 2.79 0.72 4.75 3.22 27.38 1.73 20.66 8.75 9 min. 1.35 0.78 7.66 13.69 21.53 1.61 8.51 7.88 Mean 2.72 1.00 4.79 7.63 28.95 3.04 14.94 9.01 A-86