ie 203 WOSe\ CLS: Army Caast. Ero: Res ‘ Ctr. MR 82-12 Long-Term Changes in Beach Fauna at Duck, North Carolina WHO] DOCUMENT by COLLECTION R. J. Diaz and J. T. DeAlteris MISCELLANEOUS REPORT NO. 82-12 NOVEMBER 1982 distribution unlimited. Prepared for U.S. ARMY, CORPS OF ENGINEERS COASTAL ENGINEERING RESEARCH CENTER Kingman Building Fort Belvoir, Va. 22060 ie, 62-2. Reprint or republication of any of this material shall give appropriate credit to the U.S. Army Coastal Engineering Research Center. Limited free distribution within the United States of single copies of this publication has been made by this Center. Additional copies are available from: National Technical Information Service ATTN: Operations Division 5285 Port Royal Road Springfield, Virginia 22161 as an offi designate UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) REPORT DOCUMENTATION PAGE BERS RETCONGD ET NGICORI 1. REPORT NUMBER 2. GOVT ACCESSION NO 3. RECIPIENT'S CATALOG NUMBER MR 82-12 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED Miscellaneous Report 6. PERFORMING ORG. REPORT NUMBER 8. CONTRACT OR GRANT NUMBER(a) LONG-TERM CHANGES IN BEACH FAUNA AT DUCK, NORTH CAROLINA 7. AUTHOR(a) R.J. Diaz J.T. DeAlteris DACW7 2-81-C-0002 10. PROGRAM ELEMENT, PROJECT, TASK AREA & WORK UNIT NUMBERS 9. PERFORMING ORGANIZATION NAME AND ADDRESS DeAlteris Associates P.O. Box 624 Mathews, VA 23109 11. CONTROLLING OFFICE NAME AND ADDRESS Department of the Army Coastal Engineering Research Center Kingman Building, Fort Belvoir, VA 22060 MONITORING AGENCY NAME & ADDRESS(if different from Controlling Office) G31531 12. REPORT DATE November 1982 13. NUMBER OF PAGES 48 | 15. SECURITY CLASS. (of this report) 14. UNCLASSIFIED DECL ASSIFICATION/ DOWNGRADING SCHEDULE 15a. - DISTRIBUTION STATEMENT (of this Report) Approved for public release; distribution unlimited. - DISTRIBUTION STATEMENT (of the abstract entered in Block 20, if different from Report) - SUPPLEMENTARY NOTES - KEY WORDS (Continue on reverse side if necessary and identify by block number) Beach fauna Duck, North Carolina Pier impact | ABSTRACT (Cantinue em reverse side if meceasary and identify by block number) Long-term changes in the beach fauna at Duck, North Carolina, were inves- tigated. Twenty-one stations located on three transects on the oceanside and twenty-four stations located on three transects on the sound side were sampled seasonally from November 1980 to July 1981. The data collected in this study were compared to a previous study conducted in 1976 (Matta, 1977) to investigate the potential effects of the construction of the CERC Field Research Facility pier on the adjacent beaches. No effects on the benthic continued FORM DD , jan 73 1473 EDITION OF 1 NOV 65 1S OBSOLETE UNCLASSIFIED weet Se Me eA ee eaten ane elie A te SECURITY CLASSIFJCATION OF THIS PAGE (Wien Data Entered) SECURITY CLASSIFICATION OF THIS PAGE(When Data Entered) fauna were found. Changes observed in the benthic macrofauna on the ocean beaches were well within the range attributable to the natural variation of an open coast system. The ocean beach macrofauna was observed to form a single community migrating on and off the beach with the seasons. On the sound beaches, changes were detected in the benthic macrofauna; however, these were attributed to a salinity increase during the 1981 sampling year. 2 UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE(When Data Entered) PREFACE This report was published to provide coastal engineers the results of an investigation of the long-term changes in the beach fauna adjacent to the Coastal Engineering Research Center's (CERC) Field Research Facility pier at Duck, North Carolina. The work was carried out under CERC's Effects of Construction and Operations of Field Research Facility - Duck, North Carolina, work unit, Environmental Impact Research Program, Environmental Quality Area of Civil Works Research and Development. The report was prepared by R.J. Diaz and J.T. DeAlteris of DeAlteris Associates, Mathews, Virginia, under CERC Contract No. DACW72-81-C-0002. A.K. Hurme, Ecologist, Coastal Ecology Branch was the CERC contract monitor for the study, under the general supervision of E.J. Pullen, Chief, Coastal Ecology Branch, and R.P. Savage, Chief, Research Division. Technical Director of CERC was Dr. Robert W. Whalin, P.E., upon publication of the report. Comments on this publication are invited. Approved for publication in accordance with Public Law 166, 79th Congress, approved 31 July 1945, as supplemented by Public Law 172, 88th Congress, approved 7 November 1963. Kila BD ED MER HOP Colonel, Corps of Engineers Commander and Director Il Til IV VI CONTENTS CONVERSION FACTORS, U.S. CUSTOMARY TO METRIC (SI). INTRODUCTION . METHODS AND MATERIALS 1. Transect Locations 2. Sample Locations 3. Sampling Times o geio: bdo Osos oe 4. Measurement of Physical Parameters Gaba Grosbaay c 5. Sampling Device . é 6. Biological Sample processins pnd! Analysis 5 7. Sediment Sample Processing and Analysis RESULTS 1. Ocean Beach . 2. Sound Beach . DESCGUSSIONM sa ene 1. Ocean Beach . 2. Sound Beach . SUMMARY AN ae eer 1. Ocean Beach . 2. Sound Beach . 3. Sample Design . CONCLUSIONS 1. Ocean Beach . 2. Sound Beach . LITERATURE CITED . TABLES Water temperature (°Celsius) recorded on ocean beach Salinity levels (parts per thousand) recorded on the ocean beach St 1A ec Vertical distance (in meters) from MSL of sites on the ocean beach Carbonate concentration (in grams per 100 grams) on the ocean beach Organic content of sediments (in grams per 100 grams) on the ocean beach Mean grain size (in phi) of sediments at each site on the ocean beach Page 1S 1S U7 17 NY My 15 16 17 18 19 20 Ai QO 23 24 25 26 CONTENTS TABLES--Continued Sorting of sediments at each site on the ocean beach. Skewness of sediments at each site on the ocean beach . Kurtosis of sediments at each site on the ocean beach . Taxonomic list of macrofauna collected from November 1980 to July 1981 from the ocean beach . Distribution of dominant taxa from ocean transects Community structure statistics from ocean transects Station groups from cluster analysis of all ocean beach data Water temperature (°Celsius) recorded at each site on the SOUNGMDEAGHY ah lism aie weenie peas eo deer ys Salinity (parts per thousand) recorded at each site on the sound beach Vertical distance (in meters) from MSL for each site on the sound beach Carbonate concentration (in grams per 100 grams) on the sound beach Organic content of sediments (in grams per 100 grams) on the sound beach Mean grain size (in phi) of sediment at each site on the sound beach Sorting of sediments at each site on the sound beach Skewness of sediments at each site on the sound beach . Kurtosis of sediments at each site on the sound beach . Taxonomic list of macrofauna collected from November 1980 to July 1981 from the sound beach Distribution of dominant taxa from sound transects Community structure statistics from sound transects Station groups from cluster analysis of all sound data Page 18 18 18 19 20 22 24 24 25 25 25 27 Zall Ci, 28 28 29 27 28 CONTENTS TABLES--Continued Taxonomic comparison between 1976 (Matta, 1977) and 1981 (present study) macrobenthic species collected from oceanvibeachiy Aa ue wou Taxonomic comparison between 1976 (Matta, 1977) and 1981 (present study) macrobenthic species collected from sound beach eee I IGURES Location of the CERC Field Research Facility Location of transects on the study site . Cross section of the corer used as a sampling device Page 38 42 10 iil 13 CONVERSION FACTORS, U.S. CUSTOMARY TO METRIC (SI) UNITS OF MEASUREMENT U.S. customary units of measurement used in this report can be converted to metric (SI) units as follows: == lalallala] Multiply by To obtain inches 25.4 millimeters pine 2.54 centimeters Square inches 6.452 Square centimeters cubic inches 16.39 cubic centimeters feet 30.48 centimeters 0.3048 meters square feet 0.0929 square meters cubic feet 0.0283 cubic meters yards 0.9144 meters Square yards 0.836 Square meters cubic yards 0.7646 cubic meters miles 1.6093 kilometers square miles 259.0 hectares knots 1.852 kilometers per hour acres 0.4047 hectares foot-pounds 1.3558 newton meters ANISM RAS L,OLOW se LOT! kilograms per square centimeter ounces 28.35 grams pounds 453.6 grams 0.4536 kilograms ton, long 1.0160 metric tons ton, short 0.9072 metric tons degrees (angle) 0.01745 radians Fahrenheit degrees 5/9 Celsius degrees or Kelvins! 1To obtain Celsius (C) temperature readings from Fahrenheit (F) readings, use formula: C = (5/9) (F -32). To obtain Kelvin (K) readings, use formula: K = (5/9) (F -32) + 273.15. ee ana ee sepidauedtontads wing fase} ee a thr eae ad Pe il ££ ti es : et ems eunnaael | Bete. ye Ane Gouna rcs a Vike Oy 38m Waswal pm reg emit io i IY : ti ; q ma : yy x ' PROS BUC RRT NAR el) ie ie ie BNE EW AIS Pears ; $ hin by) 4 be fe MEAT y we Sdn EE sanuibaoy £4) Aye ay, PLVESE eit See 9) - iy \ $ , a} | i ee t mi te Ae ay i ¢ : at LONG-TERM CHANGES IN BEACH FAUNA AT DUCK, NORTH CAROLINA by R.J. Diaz and J.T. DeAlteris I. INTRODUCTION This report provides additional data on the fauna communities inhabiting coastal beaches, and assesses changes, if any, in beach fauna communities caused by coastal engineering projects. The study area was Duck, North Carolina (Fig. 1), which is the site of a research pier constructed and operated since 1976 by the Coastal Engineering Research Center (CERC). A preconstruction study of the fauna of this area was undertaken by CERC, and the results of this study are reported by Matta (1977). The study area consisted of both the ocean beach, adjacent to the pier facility, and the sound beach, opposite the pier facility. The ocean beach is a high salinity, high energy environment, and in the preconstruction study, was characterized by three faunistic communities. An Hmertta community was confined to the swash zone and the inner edge of the surf zone, a Scolelepis community ranged from the margin of the surf zone to 50 meters offshore, and a Parahaustortus community extended from 50 meters offshore to an undetermined point farther offshore. The sound beach is a low energy, low salinity environment, and in the preconstruction study was also characterized by three distinct faunistic communities. The Scolecolepides community extended from about 100 to 300 meters offshore, a Leptdactylus community extended from the beach margin to about 100 meters offshore, and a small developing marsh community was also found. This postconstruction study duplicated the techniques used in the field and laboratory during the preconstruction study. The resulting data set is compared with the results of the preconstruction study to evaluate possible Significant changes in the beach fauna adjacent to the CERC Field Research Facility (FRF). II. METHODS AND MATERIALS The methods and materials used in the final sampling plan of the 1975-76 study (Matta, 1977) were also followed in this study. 1. Transect Locations. Three transects were established on both the ocean and sound beaches (Fig. 2). On the ocean beach, transect II was located due east of bench mark 16 and 47 meters north of the pier on the FRF site. Transect I was located 258 meters north of transect II. Transect III was located 305 meters south of transect II. On the sound beach, transect IV was located 118 meters south of bench mark 64; this site included a small marsh. Transect V was located 34 meters north of bench mark 64 and 152 meters north of transect IV; this site a Vo. SS oes —= -—— 7 \ N G He DN \ . »S Nt eR % CERC FRF BO. eS Wan eile | N 1 \ ! KY ( \ \\ x ‘ Duck Ne ae /@ Nags Head j r Oregon Inlet Ce) / piers. wi Sen mit on ¢ sins Sat Oi , \ 0) 48 (km) [2 ack OEE See | Figure 1. Location of the CERC Field Research Facility. ATLANTIC To Virginia Beach, Vo. OCEAN CURRITUCK SOUND fmasNosts hho l TRANSECT North Boundary 258m 200m oe een nN ay _BM 64 CERC FIELD RESEARCH FACILITY South Boundary TRANSECTyIIL Duck, N.C. | Figure 2. Location of transects on the study site. contained a shallow east-west depression causing the transect to be in deeper water than the surrounding area. Transect VI was located 200 meters north of transect V in a barren sand area with little slope, which is typical of the sound beach. 2. Sample Locations. On the ocean beach, the zero point on each transect was the landward margin of the swash zone. Thus, the sites were in the same relative position with reference to the wave activity, but changed position between the sampling series with reference to a fixed point onshore. Sampling sites were located at 3.3, 7.6, 10.6, 15.2, 30.4, 45.6, and 60.8 meters (horizontal distance) from the swash zone. When possible, samples were collected during low tide so the sites were relatively the same distance from mean sea level (MSL) over the sampling series. However, the main criterion in determining the sampling times was the sea conditions. On the sound beach transects, the zero point was the sound margin (approximately +1.0 foot MSL, 1929 datum). Sampling sites 1 to 8, respectively, were placed 15.2, 38.0, 51.8, 61.0, 68.6, 76.2, 152.4, and 304.8 meters westward of the zero point. 3. Sampling Times. The sampling of all sites was made during each of the four seasonal sampling periods: November, January, April, and July. These periods were chosen to coincide as closely as possible with Matta's (1977) study and with the period of statistically determined low significant wave heights. The ocean beach was not sampled during unfavorable sea conditions. During the fall, winter, and spring seasons, the northwest winds following the passage of low-pressure centers provided excellent periods for collecting samples in the surf zone. 4. Measurement of Physical Parameters. Sites were located to the nearest foot by stretching a precalibrated nylon line, which was anchored to the shore, over the transect. The vertical distance to the nearest foot from MSL was determined by correcting measured site water depth at the time of sampling with tide gage data provided by the CERC FRF. The temperature to the nearest 0.5° Celsius was measured near the bottom of each site using a field thermometer. A bottom water sample was also taken for laboratory analysis to the nearest part per thousand of salinity. 5. Sampling Device. The sampling device (Fig. 3) was a corer constructed of a 6-millimeter (1/4 inch) circular steelplate with a 1l-centimeter hole in the center welded to a 15-centimeter section of 8.55-centimeter-diameter (3-3/8 inch) steel electrical conduit. A 2.54-centimeter (1 inch) pipe coupling was welded to the plate over the hole, and a 2.54-centimeter steel pipe was tightly screwed into the coupling. The leading edge of the steel conduit was sharpened to aid penetration. A long handle (about 100 centimeters) was used in the shallow areas, and a short handle (about 15 centimeters) was used in the deep areas that required diving. hy U; ——— 3 3/8° Steel Conduit (85cm) Figure 3. Cross section of the corer used as a sampling device. The corer was pushed into the substrate, then extracted with the hole at the top of the handle covered. The core sample usually remained in the corer until the sample was placed in a bag, but at the deep sites the open end was covered to prevent the sample from washing out. Four biological samples, each sample consisting of two combined cores, were taken at each site. Samples were placed in prelabeled plastic bags, stored at 1° to 4° Celsius, and returned to the laboratory for processing. An additional core sample was taken at each site for grain-size and chemical analyses. 6. Biological Sample Processing and Analysis. A magnesium chloride (MgC12) and seawater rinsing technique was used to extract the organisms from the ocean core samples (Cox, 1976); rose bengal was added to a 4 percent formalin solution to aid in the sorting. All organisms, 0.5 millimeter and larger, were separated and species identified and counted. The coring and extraction techniques used for the sound samples were identical to the methods used on the ocean samples, but tapwater was substituted for the MgCl>2 seawater solution. The resulting data were analyzed for community structure statistics according to methods described previously in detail by Diaz (1977) and Boesch (1972). Cluster analysis was performed on the data according to methods detailed by Boesch (1977). Animals in all samples were identified to the lowest possible taxonomic lievieds 7. Sediment Sample Processing and Analysis. Sand particle diameter and size distribution were determined by the use of U.S. standard sieves. Taylor series sieves (phi interval) and ROTAPR shaker were used for grain-size analysis. About 50 + 2 grams of material was sieved on the ROTAPR shaker for 10 minutes. Material retained on each sieve was weighed and the mean, sorting, skewness, and kurtosis statistics were calculated according to Folk (1968). The total organic content of each sediment sample was determined by the incineration method and the total carbonate content of each sediment sample was determined by the hydrochloric acid (HC1) method (Carver, 1971). ORE SUIERS 1. Ocean Beach. a. Physical Environment. For a given collection period, the temperature was fairly consistent between transects. There was also no variation in the temperature with depth, except in July, when deeper sites on the transects had slightly lower temperatures (Table 1). The salinity was also consistent within a collection period, except in November when a range of about 1 part per thousand was observed. There seemed to be no pattern to the salinity variations during any one season. For the entire study the total range of salinity was only 31.8 to 33.7 parts per thousand (Table 2). Table 1. Water temperature (Celsius) recorded at each site on the ocean beach. November 1980 January 1981 April 1981 July 1981 —.__ Transect Ill oooocooso nnunnnnn SrOoroiorOorOr) Table 2. Salinity (parts per thousand) recorded at each site on the ocean beach. Season November 1980 January 1981 April 1981 July 1981 Transect Sige SS I II III I II III 1 31.9 31.9 31.9 52S B2hS SD Pd) 2 31.8 32.0 32.1 32.2 32.8 32.0 3 32.5 SZ 32.4 32.0 32.1 Sty) 4 32.2 31.9 32.1 32.0 Bs 2 S22, 5 32.0 31.9 B57 32.1 S2e5 Sra 6 31.9 31.8 32.8 32.0 BF 1) 32.1 7 S2ial 32.3 S58 32.5 32.2 32.3 The depth range over each transect did change from collection to collection. This reflects the dynamic and unstable nature of the beach and nearshore. The depth relationship between the three transects did not remain the same. In November transect I was deepest, in January it was transect II, in April transect III, and in July transect II (Table 3). The total carbonate content of the sediment (Table 4) showed no pattern through time with large variation at a given site. However, there were differences along the transects (arc sine transformation, analysis of variance, ANOV, a = 0.004) with collecting sites nearest the swash zone having the highest carbonates (3.3 to 30.4 meters), except transect I, where the site at 3.3 meters had consistently low carbonate. There were no differences between transects (a = 0.11). The total organic content of the sediment was uniformly low at all sites through time (Table 5). The range of total organics for the entire study was only 0.05 to 1.29 percent. This range ,is small and close to the analytical precision of the incineration method. Mean grain size, sorting skewness, and kurtosis statistics indicate that the granulometry of the sediments was variable through time for any given site and transect (Tables 6 to 9). In general, there was a tendency for the sites 30.4 meters from the swash zone and farther to have finer sediments, poorer sorting, less skewness, and higher kurtosis. b. Macrobenthos. A total of 22 taxa were identified from all ocean samples (Table 10). One of which was a small meiofaunal nemerteanlike worm that was excluded from any analysis because of its size and overwhelming dominance. The 0.5-millimeter sieve, used in this study, did not adequately quantify this worm's presence. The haustorid amphipods presented an analysis problem. Matta (1977) identified Parahaustortus longimerus as the common haustorid. In the present study, there are three morphologically very similar haustorids common in the collections. They are P. longimerus, Haustortus canadensts, and Haustortus sp. (long rostrate form); therefore, to avoid inconsistencies between Matta (1977) and the present study, all Parahaustorius and Haustortus are grouped in the category of haustorids. Other haustorid species (Amphtporeta virginiana and Bathyporeta quoddyensts) will be maintained individually, since it is unlikely that they could be confused with other species. In November a total of 16 species occurred, while in January there were 8, 9 in April, and 13 in July. Many of these species had single site occurrences for a season. If they were eliminated, the number of species occurring would be reduced to 10, 5, 8, and 10, respectively. Crustaceans were the dominant taxa, followed by polychaetes, and mollusks (Table 10). The distribution of the six dominant taxa is summarized in Table 11. Community structure statistics of occurrence and diversity (Table 12) indicate a strong seasonal influence. The lowest values were in winter (January 1981) with many sites sampled that did not have any fauna. The highest abundance and diversity, overall, occurred in the fall (November 1980) followed by summer (July 1981). Sites 30.4 meters and farther from the beach (sites 5, 6, and 7) had the highest statistics throughout the study. 16 een 3. Table 4. Vertical distance (in meters) from MSL for each site on the ocean beach. April 1981 Jul Carbonate concentration (in grams per 100 grams) on the ocean beach, Season November 1980 January 1981 April 1981 July 1981 I II III II itt III oS 1.14 3.93 2 4.60 4.14 4.57 3.54 6.00 9.77 3 3.38 BOS 2.53 3.94 5.83 10.48 4 7.88 3.78 0.06 0.47 3.91 2.50 3 4.63 4.05 Sez 1.98 15.65 11.87 0 .88 2.20 5.69 Aoi 2.99 1.96 1.16 1 ook) 1.49 1.89 1.03 1.74 2.97 Do Oy 2 -01 0.56 3.00 3.94 Table 5. Organic content of sediments rams) on the ocean beach. - Season November 1980 1981 July 1981 Transect III I III 0. 0. 0.11 0.68 0.42 0. 0. 0.30 0.85 0.16 0. 0. 0.79 0.97 0.58 0. 0. 0.08 0.81 0.55 0. 0. 0.05 0.55 0.22 0. 0. 0.10 0.84 0.16 0. 0. 0.06 1.04 0.45 Season Table 6. Mean grain size (in phi) of sediments at each site on the ocean beach, November 1980 April 1981 i) > RR Re OCOCO° un Ww 17 CORM Re kee Table 8. Skewness of sediments at each site on the ocean beach. Season November 1980 January 1981 April 1981 July 1981 pe Ae | el el ad ea Table 9. Kurtosis of sediments at each site on the ocean beach. November 1980 January 1981 April 1981 July 1981 Table 10. Taxonomic list of macrofauna collected from November 1980 to July 1981 from the ocean beach. Polychaeta Scolelepts squamata Nephtys bucera Magelona rosea Stgambra sp. Glyeera dtbranchiata Hesionid Phyllodocid Mollusca Donax spp. Acteon sp. Epttontum sp. Amphipoda Parahaustortus longimerus* Haustortus canadensis Haustortus sp. Amphtporeta virgtntana Bathyporeta quoddyensts Corophiid Decapoda Emertta talpotda Ovaltpes ocellatus Isopoda Edotea sp. Cumacea Mysidacea Occurrences! ip) Moeeinvencesln VL) Isite occurrences out of a possible total of 21 for each collection date. Combined for analyses as haustorids. 3Total haustorid occurrences for November not speciated. Table 11. Distribution of dominant taxa from ocean transects. Values represent the sum of four replicates for a total area of 0.023 Square meter. For densities per square meter multiply by 43.1. Seolelepts squamata November 1980 January 1981 April 1981 July 1981 November 1980 April 1981 IIe SIWIEIL January 1981 July 1981 Haustorids November 1980 January 1981 April 1981 July 1981 Transect 20 Table 11. Distribution of dominant taxa from ocean transects. Values represent the sum of four replicates for a total area of 0.023 square meter. For densities per square meter multiply by 43.1.--Continued Amphiporeta virgintana November 1980 January 1981 April 1981 July 1981 Transect Bathyporeta quoddyensts November 1980 April 1981 Transect Tees il Site January 1981 July 1981 Emertta talpotda November 1980 January 1981 April 1981 Transect it JUL July 1981 Oroocnoec°ocnoe SOLOS ORS 2 | Table 12. Community structure statistics from ocean transects. Ene a ae November 1980] January 1981 April 1981 July 1981 Site | Statis- T posh) kL SU yi ealla Melony) ge MPLS TaLNTara| ya 1” pki N imate 1 | Ind OI 50 | © OO 3.) WiWeanaS eNO) | ih Spp Lene LITA Lt WO)": «ADP 0) Pas Weis ta if) 0 H! OL ORI OS! O20 OO OL0 Ose O20 O10 1 O20 O50 0.0 J! 025; 0.09 0. 33 | 0) 0.10.01) 0.10., | (0..92)101.01 (0).,0) | 00) mkOn Oman R 0, 52) 0.42)0-26)| O40) 0.0). 0,0) | 0,91 OO) 0.00 | 020) "ORO ROO 2 | Ind 24) = 2254 s10M sealed vORtu) Oy 4 2525) | a4 ome Spp 20 Ue | rate Oe v2 oF On Mats Wael 41 63 aes H! O73 O20 Os0 | O00) O60) OO |) O20 WsO O50 1 143 1.25 1.50 J! 0,25) 040) 050 | 000) 0.0) 00) 1040) 0.0) ¥10.0) | 0974 t0n 70 mOnES R 0.31 040) 00 (0,080.0 O10) \J020) 0,0) 410.0) | Oxo3 eemone 3 | Ind USA Se OMe Om rT MMS SCH ET 30) 0) 2s Spp DENS cane 2a On te OMe eel Tewsiummpdlgsconuangh Sana or 2 H! OREO) WD OBL OSLO” OL0 OL) | O20 O20 O40 |) 1-21 0.0 0.54 J! OES) Oar OSE | OLOn Os MOK || CoO) Os0) O20. O52 0.0 O.54 R Onc) NS CORO) WSO On OLO OL O04) dolS O.0 0.48 4 | Ind HOS, Arg beT pels cdi hte QuklicnOlapll LSD eeitbns a cabebe? TO eT Pe 1S Spp PN NOE UMN De DS (Yere AG pe et TRON 21. MIR a H! OnE sy Se O60 OO. | O20 0.0 O20 Ost7 ©.0 0,0 J! 02.88 0479) 0} 79) 111-0 410. 0) 10.0) 1102000 0 100 OPA 7OM ORONO R OL43 1 a4 106 | 1144) 0,0) 9050" 1/1029 10. 01700 10.43) OL ONMORO 5 | Ind Zaye 1S 935.1 tS yo aye 0° (32'.9" yh 178 Sze Spp By auth eee SUPP Dhak eles hc On iets agra 3h ln Aa 4 H! yh eT AO] OoOy) Wa) LAO O50 loss: O40 | O52 0.0 1.50 J 01.89 0.:791.0,.75).1.0..97.040)..0)..664|) 0 00.01.85:100ia| ROP S400 OmmORyES R 0.63 1.17 0.56 | 0.62 0.0 0.80 |/0.0) 0.58 0.0" | 0239/00) tomsz 6 | Ind AVE MAO niin Se i A CO BS Spp A’, | Gerba S hj. SoBe el tad AGU 2 ccene Sees 4 H! 1.44 1.52 1.20] 1.15 0.0 1.20}1.59 0.72 1.55 | 0.46 0.52 1.04 J! OF 72 0.59) 0.68 | 0.72) 0.0) 0.76) \/08.80!) 0.72) 0.78) 029 NOR SomOns2 R 1-00 12117, 0.84.) 11-03, 020), 0, 78))) 1514) 043, 1.21) | Os4 Se On4SmOmoy 7 \eind GOL G5. 162 1) O Vesa Sun aa sh Sens SiC A memmnloe Spp Gi aS age Sh A ON GRY eS naam Aye be nyo) 8 3 H! 1-45, 1-02 1-08)| 020). 1.560092) | 1458) OF 92) (0.84) (01551 om monn io 0.56 0.44 0.68|}0.0 0.99 0.92 | 0.79 0.92 0.84 | 0.27 0.72 0.06 R 1.22 0.96 0.48 10.0 0.96 0.91 | 0.79 0.91 0.37 | 0.47 0.96 0.38 lind - Number of individuals in all four replicates Spp - Number of species in all four replicates H' - Diversity (Shannon-Weaver formula) J' - Evenness (Shannon-Weaver formula) R - Richness (spp - 1/1n IND) 22 The cluster analysis delineated five major station groups from all the data (sites, transects, and seasons). Station group 1 was composed of mostly near-beach sites in November and April, and middepth sites in July (Table 13). Emerita talpotda was the dominant species at these sites (Table 11). Station group 2 was the deeper of the sites in November and July. Only one site in January and two in April were included in group 2. The dominant species at this station group were Scolelepts squamata (particularly in July), Donax spp., and the haustorids. Group 3 appeared to be transitional between groups 1 and 2. In November group 3 was in between groups 1 and 2. In January and April group 2 was the deeper of the sites, indicating the absence or low abundance of many dominant species. In July group 2 was close to the beach (Table 13). Group 4 represented the depauperate stations with only a few occurrences of any species. This group occurred mainly in January with one site in November and one site in July being included. Station group 5 was all the sites that had no fauna, which occurred mainly in January, with two occurrences in April and one in July (Table 13). Since there were only seven species that occurred at more than four of the collecting sites, the species cluster was not very informative. Emerita talpotda was in a group by itself and was the only species characteristic of the shallow nearshore sites. Edotea spp. was also in a group by itself because of its rareness; it occurred only five times during the study. The other five species, Scolelepts squamata, Donax spp., haustorids, Amphtporeta virgintana, and Bathyporeta quoddyensts, were all placed together as a single species group. 2. Sound Beach. a. Physical Environment. The temperature was constant at all the collecting sites in both January and July. In November there was a slight gradient, with deeper sites on all transects having lower temperatures. In April the temperature increased from transects 4 to 5 to 6, indicating diel warming of the water as samples were collected. Collecting started early in the morning at transect 4 and ended in the afternoon at transect 6 (Table 14). The range of temperature for the study was 0.0° to 23.8° Celsius. Salinity throughout the course of the study increased from about 3 parts per thousand to a little less than 8 parts per thousand. The increase in salinity is related to the general drought conditions that existed in the Currituck Sound drainage basin during the study period. There was a slight drop in salinity in the winter (January) with the average being 2.3 parts per thousand (Table 15). The depth from MSL on any transect was never greater than 1.09 meters (Table 16). The bottom on all transects sloped gradually out to a 304.8-meter distance. From collection to collection there was a maximum 0.5-meter difference in depth at any one site along a transect, with most differences being less than 0.2 meter. The total carbonate content of the sediments was very low, except at three sites where the fragments of Rangia cuneata shells were found (Table 17). No patterns in the carbonate content could be discerned. If the three high values are eliminated, the total range for all transects and seasons is only 0.00 to 0.83 percent. 23 Table 13. Station groups from cluster analysis of all ocean beach data. See text for explanation. November 1980 January 1981 April 1981 Transect INI aC VS AIL aba WE MOM) CIAL SRE eee Lae RTS EE Table 14. Water temperature (i Celsius) recorded at each site on the sound beach. Season | ___— November 1980 January 1981 April 1981 July 1981 Iransect Site IV V VI IV Vv VI Iv V VI Iv V VI ee a | | ha 1 LEO PA EVGNO 2-0 0.0 0.0 0.0 10.0 | --- --- 23.8 | 23.8 | 23.8 2 USO | ssy Ik Aye 0.0 0.0 0.0 10.0 | ~-- 17.0 PSA) 2808 | 2303 3 16.0 {17.0 | 18.0 0.0 0.0 0.0 10.0 | 14.0 | 17.0 Z35c3 |) 2Io8" |) 2508 4 16.0 |18.0 | 18.0 0.0 0.0 0.0 10.0 } 14.0 | 15.0 PSB) 2503 1) 230 S lo.0 718.0 | 17.0 0.0 0.0 0.0 10.0 | 14.0 | 15.0 23.8 | 23.8 | 23.8 6 NGO) > |) 1 7Osg | V6.0 0.0 0.0 0.0 10.0 | 14.0 | 15.0 2359 || 2809 25.8 7 160.0 |15.0 | 16.0 0.0 0.0 0.0 MSO VASO wl alSso 25} \) 2308 1) 25.8 8 16.0 | 14.0 } 15.0 0.0 0.0 0.0 MESO I) 1260") WSs) 2328) |) 23.18 | 23.8 24 Table 15. Season Salinity (parts per thousand) recorded at each site on the November 1980 January 1981 sound beach. July 1981 <. eS IV V VI V VI IV Vv 1 3.5 3.2 3.0 = a =e 6.7 _— 4.8 7.4 7.4 7.6 2 3.2 3.4 3.4 = —— sce 4.9 a 4.8 7.4 7.9 7S 3 3,2 3.9 3.3 So8 oo 1.8 Sor 5.5 5.8 7.6 7.9 Ded 4 3.1 3.8 3.4 3.0 4.1 — 6.5 4.9 5.9 7.8 7.9 7.8 5 Sot 3.1 3.2 sae —E 1.9 6.5 6.8 6.5 7.5 7.6 73 6 3.3 3.3 3.8 DoS sie 1.3 6.5 6.8 6.0 758 7.9 7.8 7 362 3.2 3.4 Aso 1.8 2.2 5.2 6.4 5.7 7.8 708 7.6 8 3.2 3.9 3.4 28 2.3 2.4 6.7 5.0 4.9 7.4 7.4 Tes Table 16. Vertical distance (in meters) from MSI for each site on the sound beach. Season April 1981 July 1981 Transect IV Vv VI IV V VI 1 -0.15 0.15 0.00 0.09 0.21 - 06 2 30,24 0.00 | -0,09 0,03 | 0.15 ole 3 -0,15 | -0,09 0,00 70,06 0,00 eli: 4 -0.24 | -0.09 |-0.09 -0.06 0.00 -12 5 -0.24 | -0.09 0.00 -0.06 0.00 a2. 6 -0.24 |-0.15 |-0.12 -0.06 }-0.09 . 06 7 -0.39 |-0.39 |-0.30 -0.27 |-0.30 -42 8 -0.60 |-0.76 |-0.60 -0.42 |-0.39 SY) Table 17. Carbonate concentration (in grams per 100 grams) on the sound beach. Season November 1980 January 1981 April 1981 July 1981 — Transect VI IV Vv VI Iv Vv VI IV V VI 1 0. 0. 0.15 3.56 | 0.34 0.07 0.23 | 0.78 | 0.26 0.42 | 0.00 | 0.76 2 0. 0. 0.26 0.68 | 0.18 | 0.31 0.26 | 0.33 | 0.29 0.00 | 0.00 | 0.00 3 0. 0. 0.49 0.32 | 0.44 | 0.06 DS Zs) | Wests |) Wo ils 0.00 } 0.00 | 0.09 4 0. 0. 0.11 0.10 | 0.31 0.03 0.26 | 0.83 } 0.20 0.90 | 0.68 | 0.00 5 0. 0. 0.11 0.06 | 0.30 | 0.07 0.56 | 0.46 | 0.23 0.00 | 0.00 | 0.06 ) 0. 0. 0.15 0.10 | 0.55 | 0.35 0.82 | 0.09 | 0.13 0.00 } 0.00 | 0.00 7 0. 0. 0.32 0.13 | 0.55 | 0.03 0.19 UOy7 | 0)59 O22 OPS Ores) 8 0. 0. 0.12 0.13 } 0.27 | 0.40 0.69 | 0.46 | 0.36 1.23 | 0.00 | 0.00 25 Total organic content of the sediments was very low at all sites for all collections (Table 18). Total organic content ranged from 0.00 to 1.03 per- cent during the study. This range, analogous to the ocean beach organic content data, is likely within the analytical precision of the loss on the incineration method used. There were no discernible patterns of organic content within or between transects by the collection date, or between collec- tion dates (ANOV, arc sine transformation, a>0.14). The mean grain size, sorting, skewness, and kurtosis statistics indicated that the granulometry of the sound sediments was very consistent along the transects and through time (Tables 19 to 22). The total range for the mean grain size was 1.46 to 2.76 phi. Variation in the mean grain size was greatest between transects and time at the sites nearest the shore (sites 1 and 2), but this was still not much variation. Sorting was low, ranging from 0.34 to 1.26 for the study, with a weak tendency for sorting to increase nearer the shoreline. No trends were discernible in the skewness and kurtosis statistics. b. Macrobenthos. A total of 19 taxa were identified from all sound samples (Table 23). The chironomids presented the only analysis problem. Matta (1977) grouped all species as immature chironomids. In this study it was found that there were two genera Polypedilum and Cryptoehironomus present. For comparability all the chironomid species were grouped for all analyses. The dominant taxa were polychaetes, oligochaetes, amphipods, and chironomids. Within each major taxonomic group one species numerically dominated. Ltmnodrilus spp. was the dominant oligochaete and overall dominant in the sound samples. They were followed by Leptdactylus dysticus, an amphipod, and Laeonerets culvert, a polychaete. Polypedilum was the dominant chironomid but it did not occur in large numbers. Another abundant species was Scolecoleptdes viridis. Several species were common but never were abundant. They were Rangita cuneata, Gammarus sp., Monoculodes sp., Cyathura poltta, and Cryptochtronomus sp. The polychaete Streblospto benedicti was common only in July 1981, not having occurred during the other three seasons. Its appearance in July was undoubtedly due to the increasing salinity in the study area. The distribution and abundance of the more important taxa are presented in Table 24. There were only three species with only one or two occurrences. The community structure statistics of occurrence and diversity (Table 25) indicated two general trends. The first is related to time, as the study progressed community structure statistics all gradually increased, except for the number of individuals. This trend in general was not seasonal but a response to the increasing salinity. The changes in the number of individuals seemed to be neither seasonal nor salinity related. The second trend, which held for all community structure statistics, was that sample sites farther from the shore (sites 5 to 8) had higher statistics. The difference between the nearshore and the offshore sites was most pronounced in January 1981 where there were more than twice as many individuals as the offshore sites (Table 25). The sites farther from shore were deeper and better buffered from temperature extremes and ice. Community structure statistics did not show much seasonality over the course of the study. 26 Table 18. Organic content of sediments (in grams Season November 1980 er 100 grams) on the sound beach. April 1981 July 1981 Se = I <= <= IV V 1 0. 0. 0. 0.29 0.19 | 0.13 0.00 | 0 2 0. 0. 0. 0.69 | 0.06 | 0.19 0.58 | 0 3 0. 0. 0. 0.39 | 0.23 | 0.06 0.55 0 4 0. 0. 0. 0.36 | 0.19 | 0.46 0.42 | 0 5 0. 0. 0. 0.23 | 0.33 | 0.23 0.52 0 6 0. 0. 0. 0.62 0.119) |} O09 0.00 | 0 7 0. 0. 0. 0.159) ) | 10.26) ) 1) 0)..5:2 O29) 180 8 0. 0. Ws 0.13 | 0.43 | 0.65 0.22 0 Table 19. Mean grain size (in phi) of sediment at each site on the sound beach. November 1980 January 1981 April 1981 July Season Transect IV V VI 1V Vv VI IV V VI 1V Vv 1 2.36 | 2.49 | 2 De 2.46 | 2.38 1 DeAgwa|i229 De 2.40 | 2. 2 DAD |\/2o82 |\ 2 Ds 2.54 | 1.46 2 2.50 | 2.76 2, 2.36 | 2. 3 2.49 | 2.45 | 2 De 2.43 | 2.48 2 2.50 | 2.40 2. Bo || De 4 Aon | Bsa 2 Be 2.49 | 2.46 2 2.45 | 2.47 Dy Bes) Qo 5 DOG) Qasy \\ 2 De 2.46 | 2.48 2 2.43) | 2ua Dy. 2eSssileee 6 2.42 | 2.55 | 2 De 2.43 | 2.41 2 2.51 | 2.48 Re Dod || 2. 7 2E45 2249) ||) 2 De BAY || Rese 2 2.40 | 2.31 De Ro ||) 2e 8 Das | RAS || 2 De 2.49 | 2.50 2 2.47 | 2.35 Re 2) |) 2. Table 20. Sorting of sediments at each site on the sound beach. Season November 1980 January 1981 April 1981 Transect VI IV V VI IV V VI vl 1 0. 0.53 0.41 | 0.42 | 0.54 1.26 | 0.45 0.52 0. 0.40 2 0. 0.63 0.44 | 0.43 | 0.44 0.39 | 0.46 0.53 0. 0.41 3 0. 0.46 0.40 | 0.50 | 0.42 0.38 | 0.41 0.50 0. 0.43 4 0. 0.45 0.38 | 0.40 | 0.46 0.52 | 0.39 0.45 0. 0.46 5 0. 0.45 0.44 | 0.45 | 0.39 0.46 |0.48 0.43 0. 0.63 6 0. 0.49 0.45 | 0.42 | 0.47 0.45 ]0.40 0.42 0. 0.45 7 0. 0.51 0.44 | 0.41 | 0.46 O68) 1) OsSil Ooi 0. 0.47 8 0. 0.40 0.36 | 0.40 | 0.37 0.38 | 0.37 0.37 0. 0.43 27 Season ONAN HBWN Ee Table 21. November 1980 January 1981 April 1981 Skewness of sediments at each site on the sound beach. IV V -0.58 | 0.13 0.00 | 0.01 -0.01 0.00 -0.20 | 0.06 -0.09 |-0.05 -0.77 | 0.00 0.00 |-0.07 -0.03 |-0.07 Table 22. Season November 1 2 3 4 5 6 7 8 te a Ree NR eee Kurtosis of sediments at each site on the sound beach. January 1981 April 1981 July 1981 Le ee ee ee co ee ee el Se eT nN wn i So emo s Ree ee eee 1. 1. 1 1. 1. 1. 1. 1. Ll cel eel cel ee ce ce Ree Re ee ee nN MN 28 ee Od tO Table 23. Taxonomic list of macrofauna collected from November 1980 to July 1981 from the sound beach. Occurrences! Nemertea Unidentified sp. 0 0 0 1 Polychaeta Scolecoleptdes viridis 0 0 0 17 Laeonerets culvert 24 23 15 23 Lystpptdes grayt 3 0 0 0 Polydora ltgnt 1 0 0 1 Oligochaeta Limnodrilus spp. 24 23 21 23 Hirudinea Glossiphonid 1 1 0 0 Mollusca Rangta cuneata 8 12 4 8 Macoma sp. 0 0 0 6 Amphipoda Leptdactylus dystteus 25 213 23 24 Gammarus sp. 5 4 9 4 Leptochetrus plumulosus 0 0 9 5 Monoeulodes sp. 5 1 13 2 Corophtum sp. 0 0 2 2 Isopoda Cyathura poltta 6 3 6 5 Edotea triloba 1 0 0 0 Chironomidae2 Polypedtlum spp. 8 21 15 16 Cryptoehtronomus sp. 0 7 9 4 ee ee ee eee ee lsite occurrences out of a possible total of 24 for each collection date. 2combined for analyses as chironomids. 29 Table 24. Distribution of dominant taxa from sound transects. Values represent sum of four replicates for a total area of 0.023 square meter. For densities per square meter multiply by 43.1. Seolecoleptdes viridis Transect 1 1 70) 1 ORO 22 2 0 2 Ogu On 0 1 ORO 22 aziz. Ad) sal 5 GO O +2 1 0 l AS Ow eS) 26 oO. 4 1l 0) 0) 2 0 1 255 tO lS, 1l Te 35) 5 Sian 1 15 } ey ah 22 8 8 6 1 QO 8 il Oe 22 Bian 22) 17 WT 2 7 7 8 7 8 \@ 2 28 3 40 3 Ome 4, 8 8 5 9 OTOL a2. Oey 8) BY 23 6 Zi Streblospto benedictt November 1980 January 1981 April 1981 VAT Vial VV VT (RE SR a aT I 1 Q? ©. 0 O..@ OO: @ OO. 2 O° 0 © QO" OO 0) § @ > © 2 Ona: 3 0 O 0 @--'@) @ Q® @ © Suere 4 4 OO 0 O. 0H © © 0 1 1 5 ORONO OQ -@ © OG OM» @ SS Se 6 > @ © OO Oo 0) © >» @ 0 1 1 7 Y O -@ QO @ Q® @ ‘© 4 4 0 8 090 0 QO 0 O OO BS ©) a! Laeonerets culvert November 1980 January 1981 April 1981 July 1981 Transect IV VV IV V VI IV We Wat TV VI Site al be ae bead 1 30 LS: 22 4 2 0 0 1 39 290 44 2 21'S 9 PISO L2. 0 S Aly 212 30. 30 3 as) I) 2 So a) 50) 1 a) 0 Slee 4 4 SH ail 28 3 SO 4 0 3 41 58 35 5 SSS 2S) Q, AS 27 3 ZnO Oy XS. So) 6 LOM Bie 0 7 Wine) 0 O° 5 2 Gil Ai 7 36 S25 2 OWae ie2.9) 15 oO 14 18 28 23 8 JO. 22 NS al Busy 9 eal i wil 3 28 34. 39 Limnodrtlus spp. November 1980 January 1981 April 1981 July 1981 Transect IV Vivi IV V VI IV VV IV Vv VI Site 1 220 3 3 19 1 1 26 Sree Ohe22 4 u 0 2 Sih, 26 1 29 3 1 42 3 1 9 6 16 3 120 2 4 iba 1 0 &D O 3 115 ) 8 4 172 Bg) 14 10 i 26 2 5 6 13 5 5 Ge! 0) 2 12426) 14 5 1 11 3 9 6 350 20 9 16 229) 2) 2 Heh) NZ 9 7 108 23) tS) CONG IS 62 O) Bey WS} SE) S4 8 52 40 22S Zam a4 45 46 42 230 195 98 30 Table 24. Distribution of dominant taxa from sound transects. ' Values represent sum of four replicates for a total area of 0.023 square meter. For densities per square meter multiply by 43.1.--Continued_ April 1981 Transect IV Vieaval IV V VI iL 1 0 0 0 (0) 0 0 0 0 5 0 0 2 1 1 0 0 2 0 (0) 0 0 3 0 0) 3 0) 0 0 1 0 0) 0 0 0 0 i 0 4 0 (0) 0) 23 0 0 0 0 0 0 0 0 5 2 0 0 4 0) 0 0 0 0 0 0) 0) 6 2 0 0 1 0 1 0 0 0 2 0 0 7 (0) 0 1 6 3 4 2 0 1 2 0 3 8 0 0 1 4 1 4 10 2 (0) 6 7 (0) Leptdactylus dysttcus November 1980 July 1981 Transect rf) BI DH LUN rN NnkOAN AIH Gammarus sp. November 1980 January 1981 April 1981 Transect VIVANT i Ww IV. V_ VI SHRED [2 IO wig Rs | ae | ER CIDNEWNE SCOCCOCOrOW OO) CO) =O) Oli "00 ocoooococo°co Ssoooocorrf SLOrOrOeOsrOrre) rFoocOoracoo SCOOCOCOONOF rFPooofhkow —_ SCCOOCDCONNO cooooo0occoco oooooco°co =o Oo Oo = oo Monoculodes sp. 1981 VV Januar April 1981 IV November 1980 VV Va Transect ooroco°c*ccoco COOrnNoOoCoc°o CoOoOrroococe PBWUrFODOCOO ooooorre coooooo°co SOOO lolOorore FPONFNWOF WrIADMH We SROLOLOLOLOT ae: SOLO LOLOLOLOre. OOOO 2S) © ooOrON NN 3| Table 24. Distribution of dominant taxa from sound transects. Values represent sum of four replicates for a total area of 0.023 square meter. For densities per square meter multiply by 43.1.--Continued Cyathura polita Transect Site November 1980 January 1981 April 1981 July 1981 I Wat VV eave IN AY AL LV VA oe eo OND HLWNrR ooooooc°;cf SDOOrFOCOrRFNN SLO LOA TO.OLOrS. OOo Ol OrOrOr) SIOCVOLOXLOR OnE) SOLOLOVOROROROKS! CONOCOOCON OWOrecCceOo°o SF OCONln Oot ©) oooorewcjosf SVOLOeA FT OROe TO) ONOOCOCOCOO SE ——————————E————EE————EE—E—— Chironomids November 1980 January 1981 April 1981 Jul Transect 32 Table 25. November 1980 ZUS Si 16 9 7 2 1.08 1.62 0.34 0.58 1.43 1.53 626 122 6 7 0.53 1.84 0.21 0.66 0.78 1.25 1G 99 O89. 6 4 4 Woy Oot 0.45 0.35 0.97 0.66 221 77 5 4 3 1.07 1.41 0.46 0.70 0.74 0.69 209 109 S 8 8 O92) 72)521) 1380 0.40 0.74 0.60 0.75 1.49 1.48 384 7 6 5 5 0.58 1.76 1.89 0.23 0.76 0.81 0.84 0.87 0.95 15s . Of) 4 5 5 LS 69 TESS ONS 2073) 063, 0.60 0.94 0.87 102 41 67 4 5 6 1.42 0.71 0.65 Number of individuals in all four Number of species in all four replicates - Diversity (Shannon-Weaver formula) Evenness (Shannon-Weaver formula) Richness (spp. - 1/1n Ind) 33 Community structure statistics from sound transects. April 1981 S27 wes 5) 67 U 4 5 1.03 0.42 1.62 0.37 0.21 0.70 1.03 0.61 0.95 72 59. 6 6 7 2.19 0.78 1.39 Ne) 27 7 3 w 2.63 0.94 1.82 23) SE) replicates July 1981 69 357 V7 7 4 4 92 0.68 1.42 0.72 0.39 0.51 Ides) 0.58 0.69 93 94 146 8 6 6 2.00 0.78 1.00 The cluster analysis did not produce a concise grouping of stations with data trends that could be attributed to season, depth, or sediment statistics. At the group 6 level there was a mixing of stations from different seasons and locations along the transects (Table 26). Group 1, mainly transect IV in November, and the deepest stations (sites 7 and 8) from all transects in July, had the highest densities of the dominant species and also tended to have low evenness. Group 2, mainly transect IV in January and April, and the deeper sites from November, January, and April on all transects, had lower densities of dominant species and occurrences of Rangta cuneata and chironomids. Group 3 was the only station group to be entirely made up of one collection period, April, and represents stations of low community structure statistics. Group 3 was primarily transects V and VI. Group 4 also represented stations with low community structure statistics, but mainly in January, for transect V. Group 5 was mainly stations (sites 2 to 5) on transects V and VI in November and transect VI in January. Group 5 appears to be transitional between groups 3 and 4 in its character, having low densities of some dominants, but not others (Table 24). Group 6 is mainly stations (sites 1, 2, 4, 5, and 6) from July and represents more the increased salinity through time than the seasonality. The abundance of freshwater forms (Gammarus sp. and chironomids) decline while estuarine forms increase (Leptdactylus dysttcs, Rangta cuneata and Laeonerets culvert). In July there was also the appearance of additional estuarine forms that did not occur previously (Streblospto benedictt and Macoma sp.). Table 26. Station groups from cluster analysis of all sound data. See text for explanation. April 1981 November 1980 January 1981 i oe Ne i ea IV eVGA ae Be a at July 1981 IN WW Wal Transect CONDUNARWN FE NOnNAPUHPHA HA NONNUUNUNMN & NNWNWH De NOWNWWNWDBa Pw NONWWWDBwn do PRE DDDAHK AA PEDADAAUNAGA BPNDDAAAAA NPP RP RP eRe BANUUNUNMNN NONAUNUMUNN& RPrRNrRNNN From the species cluster analysis, four species groups were identified that related to dominance and the increasing salinity. Species group 1 was composed of Linnodrilus spp., Scolecolepides viridis, Laeonereis culvert, and Leptdactylus dysticus. These species were the major dominants that Occurred at most stations for all collections. They were the most characteristic of station groups 1 and 2. Species group 2 was Cyathura polita, Gammarus sp., Monoculodes sp., and Leptocheirus plumulosus. Group 2 did not seem to be characteristic at any station group, but is diffusely represented in all station groups. Species group 3 was Rangta cuneata and chironomids, which were characteristic of the deeper stations in station groups 1 and 2. Species group 4 was Streblospto benedictt and Macoma sp., which were the most characteristic of station group 6 for July. 34 The cluster analyses indicate a complex pattern of change through time. There was a shifting of the community structure that was in part due to the seasonality and increasing salinity. Station groups 1 and 2 represent the dominant fauna throughout the seasons. They are also the stations where species patterns did not seem to vary. If these two station groups are then considered constants, there is a progression of the other four station groups through time. Station group 5 was most typical of November, group 4 was typical of January, group 5 was typical of April, and group 6 was typical of July (Table 26). The faunal changes that occurred at these four station groups coincide best with the salinity. However, station group 4 does seem to reflect the severe water conditions of low abundance and species diversity. IV. DISCUSSION 1. Ocean Beach. a. Present conditions. The physical environment at the Duck ocean beach is typical of the high energy, sand beaches found along exposed ocean coasts. The sediment is graded from coarse sand in the swash zone to finer sand 30 to 60 meters from shore. The bottom is very unstable, creating a physically dominated environment. The fauna inhabiting these high energy beaches, which are very extensive environments along the Atlantic and Gulf of Mexico coasts, while not diverse, has been remarkably successful in coping with unstable substrate caused by high kinetic wave energy (Croker, 1967; Dexter, 1976; Holland and Dean, 1977; Shelton and Robertson, 1981). Emerita spp., Donax spp., and haustorid amphipods are three dominant groups of species that inhabit ocean beaches all around the world (Pearse, Humm, and Warton, 1942; Dahl, 1952; Dexter, 1972, 1974, 1976; Diaz, 1980). These three taxa were also dominant at Duck, accounting for 33 percent of all taxa and 71 percent of all occurrences (Table 10). imertta talpotda was the only species at Duck, North Carolina, to be common in the swash zone. It also exhibited a seasonal migration off the beach to deeper water in the winter and back to the beach in spring and summer . While the Emerita talpoida was not separated by sex, its pattern of recruit- ment seemed to follow the sequence as described by Diaz (1980) and Bowman — (1982) for the Duck, North Carolina, beach and for Bogue Banks, North Carolina, populations. At Duck, North Carolina, the highest numbers of immature individuals, summer of 1980 recruits, occurred in November 1980. In January 1981 they were not present in the sampling area probably having moved farther offshore than the transects. This offshore migration was documented by Bowman (1982). By April they were moving back to the beach and increasing in size. In July there were numbers of large ovigerous females. The Donax spp., which may reach densities as high as 60,000 per square meter (for comparison 1,392 in 0.023 per square meter) (Mikkelsen, 1981) on other beaches, was not consistently dominant at Duck. This species only occurred in any great number in November 1980 and then only subtidally and not intertidally as most other Donax spp. populations (Pearse, Humm, and Warton, 1942). The subtidal occurrence of Donax spp. at Duck may be related to the coarse grain size and the steep slope of the beach (Edgren, 1959). 35 The haustorid amphipods were the most diverse taxonomic group to occur on the Duck, North Carolina beach. Five species occurred with varying regularity. The genera Haustorius and Parahaustorius were the most common. Haustorius spp. occurred high in the swash zone to subtidal, while Parahaustorius longimerus was mainly subtidal. The other haustorids were mainly subtidal (Table 10). Scolelepis squamata, a spionid polychaete, which is common in high energy, sandy areas (Shelton and Robertson, 1981) was only common in July 1981. This may have been the result of a late spring or early summer recruitment, since most of the individuals were very small. No other species occurred at Duck that were other than incidental (five or fewer occurrences out of a possible 84, Table 10). This low number of species, while typical of the ocean beach, is a bit lower than was reported for other beaches (Pearse, Humm, and Warton, 1942; Dahl, 1952; Shelton and Robertson, 1981). The maximum species diversity (H') seasonally for the Duck beach--1.62 in November, 1.56 in January, 1.59 in April, and 1.67 in July--was lower than the average diversity reported by Shelton and Robertson (1981) for the surf exposed Texas beaches. Even if the Duck haustorids were considered separately, maximum diversity would not reach the average diversities reported by Shelton and Robertson. The Duck ocean fauna formed a single community unit. While Emerita talpotda was the only important species in the swash zone, it also occurred subtidally. This agrees with other beach studies that indicate a single community inhabits the high energy ocean beach environment (Pearse, Humm, and Warton, 1942; Dahl, 1952; Shelton and Robertson, 1981). The Duck beach fauna then was typical of other beaches in this respect. While Knott, Calder, and Van Dolah (1982) found distinct communities in the intertidal and subtidal habitats at beaches around Murrells Inlet, South Carolina, their transects were about 1 kilometer long. Where Knott, Calder, and Van Dolah's stations were similar to the current study in distance from shore, their data also indicated a single community. b. Comparison between 1975-76 and 1980-81. Matta (1977) surveyed the Duck beach in 1975-76. The present study occupied the same transects and stations as Matta and also employed the same methodologies. It is therefore possible to compare the two studies and establish what changes have occurred in 5 years. Matta's (1977) data are continually referred to as the early study or the 1976 conditions. On the average, temperature and salinity were higher in 1976. The depth was variable for both studies, but stations at the offshore end of the transects were deeper in 1976. The carbonate and organic content of sediments were similar between 1976 and 1981. While sediments appeared to be coarser in the beginning of the 1976 study, there is no overall difference in the grain size between 1976 and 1981. Sorting, skewness, and kurtosis are also similar between studies. It appears that the physical sedimentary environment at the sites sampled has not changed from 1976 to 1981. While the temperature and salinity are different, they are well within the range of the natural variation that open coast systems experience. 36 In comparing the fauna (only polychaetes, mollusks, and crustaceans) the qualitative similarity (Jaccard's coefficient) is 0.67, which is a moderate similarity for the overall fauna. If the comparison is made by a major taxonomic group, then the similarity between studies is 0.88 for polychaetes, 0.33 for mollusks, and 0.64 for crustaceans. The polychaetes are very similar between studies with two taxa occurring in 1976 that did not occur in 1981, and one taxon in 1981 that was not found in 1976. The only mollusk in common was Donax spp., with two other species occurring in 1976 that did not occur in 1981, and vice versa. The crustacean fauna had seven species in common and four that occurred in one study, but not the other. The overall number of species was 22 for 1976 and 21 for 1981. If only the four top dominant taxa are compared, they are identical between studies (Emertta talpotda, Donax spp., Scolelepts squamata, and haustorids). Species differences between the studies occur only in the uncommon species (Table 27). In 1976, the Emerita talpotda remained in the swash zone throughout the study because the temperatures on all four collection dates were always above 10° Celsius. In 1981 the temperature in January was low, 5° Celsius, and the Emertta talpotda left the swash zone. Densities of this decapod were lower in November 1975 than in 1980, but well within the range described by Diaz (1980) and Bowman (1982) for yearly variation. In the other comparable collections (April to July) densities were surprisingly similar between 1976 and 1981. In 1976, the Scolelepts squamata was more common, occurring at more than 70 percent of all collecting sites. In 1981 it occurred at 62 percent of the sites. Densities in 1976 were comparable to those in 1981, being slightly higher overall from April to July 1976. The November collections were similar, averaging 86 worms per square meter in 1976 and 74 worms per square meter in 1981. Scolelepts squamata occurred in and near the swash zone commonly in June to July 1976. In July 1981, when it was most abundant, it had one occurrence in the swash zone. In 1976, Donax spp. was widely distributed in June and July with occurrences in and near the swash zone. In July 1981, Donax spp. was virtually absent. In November 1975, there were few occurrences of Donax spp., all being found farther offshore. In November 1980 it was common, but only offshore. From the dynamic nature of this species populations (Mikkelsen, 1981) the differences between 1976 and 1981 are not outside the range of variation usually found in beach populations. The haustorid amphipods (Parahaustorius longimerus in Matta, 1977) were distributed similarly in 1976 and 1981, with there being slightly higher densities in 1976. After comparing the four dominant species, it seems that the basic species distributions and abundances are similar or within the ranges of variation reported in the literature. The species diversity (H') for both studies was low, with a slightly greater range in 1976 of 0.00 to 1.85. In 1981, the range of diversity was 0.00 to 1.67. One distinct faunal community seemed to be present in both S) [/ Table 27. Taxonomic comparison between 1976 (Matta, 1977) and 1981 (present study) macrobenthic species collected from the ocean beach. Taxon Polychaeta Seolelepts squamata Sptophanes bombyx Nephtys bucera Magelona rosea Stgambra sp. Microphthalmus sezelkowtt Travista carnea Glycera dtbranechiata Eteone heteropoda Hesionid Phylodocid Mollusca Donax spp. Ensts sp. Anadara ovalis Acteon sp. Epttontum sp. Amphipoda Haustorids Amphtporeta virgintana Bathyporeta quoddyensts Corophidd Jassa falecala Decapoda Emertta talpotda Ovaltpes ocellatus Pagurus longtearpus Isopoda Edotea sp. Cumacea Mysidacea 38 1976 1981 + + + t+ 1976 and 1981. While Matta (1977) felt there were two other communities in the deeper water, analysis of the 1981 data for species patterns showed there was no distinct deeper water community. Considering the great similarity of dominants, it is likely that cluster analysis of the 1976 data would produce the same single community found in 1981. 2. Sound Beach. a. Present conditions. The physical environment at the Duck sound beach is characteristic of the low energy, low salinity, sandy sounds in the North Carolina area. Sediments are virtually 100 percent sand with low organic and carbonate contents. The grain size of sediments is consistent, being fine sand. The water temperature was influenced by the air temperature. In January the temperature was 0° Celsius with a 5- to 10-centimeter ice cover. Temperatures higher than 24° Celsius do occur in the summer due to the shallowness of the sound system. Matta (1977) recorded 35° Celsius in July 1976. The salinity during the study increased from about 3 to 8 parts per thousand, reflecting the sensitivity of the system to the prevailing drought conditions. The fauna that inhabits these low salinity, shallow-water areas has to be able to cope with temperature extremes encountered during winter and summer. While not diverse, the fauna is generally a mixture of the eury-tolerant freshwater and estuarine species. Shifts in the balance between these forms are determined by what appears only slight shifts in salinity, on the order of 5 parts per thousand (Tenore, 1972; Diaz, 1977; Boesch, 1977). Oligochaetes, polychaetes, chironomids, and at times amphipods or mollusks are the dominant taxa in the low salinity areas in temperate estuarine systems along the North and South American and the European coasts (Tenore, 1972; Leppakoski, 1975; Diaz, 1977, 1980). Within any one of these major taxonomic groups there are generally only one or two species dominant in any particular area. In the Duck sound the dominants were Limnodrilus spp. (very likely all L. hoffmetstert from several mature specimens examined), an oligochaete, Laeonerets culvert and Scolecolepides viridis, both polychaetes, Polypedilum sp., a chironomid, and Lepidactylus dysticus, an amphipod. While the clam Rangia cuneata is a dominant in the deeper water sampled, it was not a dominant in the shallow water sampled. These four dominants accounted for 21 percent of all taxa and 71 percent of all occurrences (Table 23). The Genus Limnodrilus contains the most widely distributed and eury- tolerant species of oligochaetes known (Brinkhurst and Cook, 1974, Diaz, 1980). At Duck, North Carolina, Linmnodrilus spp. was the top numerical dominant on every collection date, reaching densities as high as 24,870 per square meter and averaging 2,290 per square meter for the entire study. While many Ltmmodrilus species can be pollution indicators, particular L. hoffmetstert, which is likely the only species at Duck (Brinkhurst and Cook, 1974), their presence at Duck does not indicate a degraded environment. At Duck the Limnodrilus spp. is part of a low salinity community in a physically controlled environment. They are well adapted to salinity (Diaz, 1980) and temperature (Kennedy, 1966) stress. Through the course of the study, the size of the Limnodrilus spp. was always small with very few mature specimens. This is likely a result of the salinity, which is very close to their maximum reported field tolerance (Diaz, 1980). 39 The Laeonerets culvert is a eury-tolerant nereid polychaete that is common over a wide range of salinity, from 0.5 to at least 18 parts per thousand (Tenore, 1972; Diaz, 1977). It was widely distributed at Duck, being most abundant in July, possibly as a result of the higher salinity. As with Linmmodrilus spp. most of the Laeonerets culvert were juveniles. They were only scattered occurrences of adult individuals from each collection date. Laeonereits culvert was always uniformly distributed with depth and between transects. In January it was the only dominant to occur in the same densities at the nearshore stations (sites 1 to 4) and offshore stations (sites 5 to 8). Its lowest densities occurred in April with about twice as many worms occurring at the offshore stations (Table 24). The Seolecolepides viridis, a spionid polychaete, is a eury-tolerant species with a large salinity range from 0.5 to 25 parts per thousand. It seems to do best in the 5 to 10 parts per thousand range. At Duck it commonly occurred in all collections, but was never really dominant until April and July, when salinities were more than 5 parts per thousand (Table 24). Unlike the other annelid dominants when Scolecoleptdes viridis occurred, the individuals tended to be larger. The chironomid larvae are predominantly freshwater fauna, but there are several Genera, including Polypedtlum and Cryptochtronomus, that are eury- tolerant (Roback, 1974). Polypedilum sp. was the dominant species at Duck. Chironomids were common but were never abundant. The greatest densities occurred in April and again in January. The Leptdactylus dystteus, a haustorid amphipod, has the lowest salinity tolerance of the haustorids. It ranges from 0.5 to about 15 parts per thousand. It is also a eury-tolerant species that is widely distributed in low salinity zones of estuaries. At Duck, Leptdactylus dystteus occurred about as frequently as Limnodrilus spp. and was second in numerical dominance, averaging about 1,025 per square meter for the entire study. The greatest densities occurred in July, followed by November. For all collection dates there were more Lepidactylus dysticus in the nearshore stations (sites 1 to 4) than the offshore stations (sites 5 to 8), even in January with a 5- to 10- centimeter ice cover (Table 24). The Duck sound fauna formed a single community unit for any one collection date. There was a gradual changing of the community from November to July. While the dominants were the same throughout the study the less common species changed with three species dropping out after November (Lystpptdes grayt, Edotea triloba, leech) and six appearing (Streblospto benedtett, nemertean, Macoma sp., Leptochetrus plumulosus, Corophium sp. , Cryptochtronomus sp.). The leech was the only freshwater form to drop out and Cryptochtronomus sp. was the only freshwater form to be added after November. All other species changes were due to estuarine species. Despite these changes there was still a single community characteristic of the Duck sound in July. The qualitative similarity (Jaccard's coefficient) between November and the other collections was 0.83 in January, 0.72 in April, and 0.69 in July, indicating the gradual shift in the nondominant taxa. Cluster 40 analysis also documented this gradual shift. The fauna assemblage in the sound at Duck is not unique. The same species occur in similar community groups in other estuarine systems (Diaz, 1977). b. Comparison between 1976 and 1981. Matta (1977) surveyed the Duck sound in 1975-76. The present study occupied the same transects and stations as Matta and also employed the same methodologies. This facilitates the 5- year comparison between the two data sets. Matta's (1977) data will be continually referred to as the early study or the 1976 conditions. The water temperature appeared higher in 1976, but the only month where samples were collected in 1976 and 1981 was July. In July 1976 the water temperature was 7° Celsius higher than the sampling date for 1981. This is well within the monthly range of temperature that is expected for that period of the year. Salinity was lower in 1976, being about 2 parts per thousand in October 1975 and March 1976, and about 3 parts per thousand in May and July 1976. In 1981 salinity went from about 3 parts per thousand in November 1980 to 8 parts per thousand in July 1981. This is a substantial increase in salinity considering the sensitivity of the low salinity fauna to changes in salinity (Leppakoski, 1975; and Diaz, 1977). The overall depth at the transects increased from 1976 to 1981 by about 0.25 meter at many sites. The sediment organic and carbonate content were slightly lower than in 1976, but since 1981 values were very low, this is probably not an important change to the fauna. The mean grain size was similar between studies, except in May 1976, when there appeared to be exactly a l-phi decrease in grain size at all sites sampled. By July 1976 the mean grain size had increased from 2.3 to 2.5 phi, the approximate model value for both studies. Sorting was similar, but skewness and kurtosis were greater in 1976. The major change in the physical environment between 1976 and 1981 was the increased salinity. The other changes (depth, skewness, and kurtosis) probably did not have any biological significance. In comparing the fauna (only annelids, mollusks, crustaceans, and chironomids) the qualitative similarity (Jaccard's coefficient) is 0.73, which is a moderate overall resemblance of the fauna from 1976 to 1981. If the comparison is made on the major taxonomic level, then the similarity between studies is 0.73 for annelids, 0.40 for mollusks, and 0.80 for crustaceans (Table 28). Chironomids cannot be compared since they were not speciated in 1976. All polychaetes from 1976 occurred in 1981, plus two other species (Polydora lignt and Streblospto benedictt). Among the oligochaetes there seemed to be a complete change in species. Matta (1977) reported finding Peloscolex sp. and Lumbrtculus sp. In the 2 to 3 parts per thousand salinity range, which existed in 1976, the only oligochaetes known to commonly occur are tubificids in the genus Linmodrilus and Tubificodies (= Pelosecolex) heterochaetus (Diaz, 1980). Most Lwnbrtculus species are robust worms that resemble earthworms and prefer high organic sediments. The samples from the sound are not the correct habitat for Lwnbriculus sp. Considering the possible differences between the 1976 and 1981 identifications, oligochaetes will be compared only as a higher taxon. The only mollusk in common between 1976 and 1981 was Rangta cuneata. Two other freshwater forms (Physa sp. and Ferrissita sp.) disappeared and Macoma sp., an estuarine species 4 Table 28. Taxonomic comparison between 1976 (Matta, 1977) and 1981 (present study) macrobenthic species collected from the sound beach. Polychaeta Seolecoleptdes viridis Laeonerets culvert Lystpptdes grayt Polydora lignt Oligochaeta Mollusca Rangia cuneata Macoma sp. Physa sp Ferrissta sp. Amphipoda Lepidactylus dysttcus Gammarus sp. Leptochetrus plumulosus Monoculodes sp. Corophtum sp. ITsopoda Cyathura poltta Edotea trtloba Decapoda Callinectes sapidus Insecta Chironomidae Tabanidae Cerotopogonidae Hirudinea Glossiphonid 42 appeared in 1981. Six crustaceans occurred in both studies. One freshwater form Cambarus sp. and one estuarine form Callinectes saptdus did not occur in 1981, and one estuarine species Corophium sp. occurred in 1981, but not 1976. Overall there were 16 taxa in 1976 and 17 in 1981. Of the five dominant species, four were the same in both studies (oligochaetes, Scolecoleptdes virtdis, Leptdactylus dystteus, and chironomids). In 1976 Monoculodes sp. was dominant, but not in 1981. In 1981 the Laeonereis culvert was dominant but not in 1976. In 1976, oligochaetes were not as abundant as in 1981, averaging 1,660 per square meter in 1976 and 2,290 per square meter in 1981. For both studies densities for transect IV were higher than the other two transects (the only exception was in March 1976). In 1976 Scolecolepides viridis tended to occur at stations farther offshore (stations 5 to 8) and averaged 69 per square meter for the study. In 1981 it averaged 500 per square meter for all collections, but Seolecolepitdes viridis became very abundant in April 1981 when salinity increased over 5 parts per thousand. In November 1980 and January 1981 it averaged 260 per square meter and in April and July 1981, 750 per square meter. Laeonerets culvert occurred only five times in 1976, in July, at low abundances. In 1981 it was the second numerically dominant species and occurred at almost every station. The Leptdactylus dystteus was common and abundant in 1976, averaging 540 per square meter. It increased in abundance by a factor of two from October 1975 (300 per square meter) to July 1976 (700 per square meter). In 1981 Leptdactylus dystteus was abundant, averaging 1,025 per square meter. The trend in this species is consistent with the increased salinity. Monoculodes sp. was much more abundant in 1976 than in 1981. In 1976 it was a dominant species occurring at 75 percent of all stations over the entire study. In 1981 Monoculodes sp. was uncommon occurring at only 22 percent of the stations. In 1976 it averaged 392 per square meter and only 151 per square meter in 1981. The decline in abundance of Monoculodes sp. is not related to the salinity change. It is an estuarine genus that should have been favored by the higher salinity. The chironomid larvae were widespread and abundant in 1976, occurring at almost all stations. They averaged 435 per square meter. By 1981 their importance had declined, occurring at 67 percent of all stations with an average abundance of 206 per square meter. While it is not known which chironomid species were abundant in 1976, the species present in 1981 were salt tolerant (Roback, 1974). The decline in chironomid, and possible shift to salt-tolerant forms, from 1976 to 1981 appears to reflect the increased salinity level. Species diversity (H') for both studies was low. The range of diversity for 1976 was 0.33 to 2.33, compared with 0.00 to 2.52 in 1981. These ranges seem typical for low salinity habitats (Boesch, 1972; Diaz, 1977). Low diversity was due to both low evenness and richness. In 1976 Matta (1977) identified three communities in the sound. However, with the possible 43 exception of a marsh area on transect IV in 1976 there did not seem to be three distinct communities. There was an overlap of the dominant species between the delineated community boundaries. With the low species number that occurred in the sound it is likely that they formed one basic low salinity community. In 1981, while salinity had increased there was still a single community in the sound. The marsh area on transect IV had receded shoreward of the first sampling site leaving all three transects with a very uniform physical environment. However, in 1981, transect IV did have higher abundances of individuals compared with the other transects. This is most obvious in the November collections and may be a relic condition associated with the marsh that was once present on the nearby existing marsh or both. There was a gradual shifting of the sound community in 1981, which attributed to increasing salinity. The major taxonomic dominants in both 1976 and 1981 were the same, but several of the species did change. V. SUMMARY 1. Ocean Beach. The ocean beach environment at CERC's FRF, Duck, North Carolina, was found to be typical of ocean beaches along the east coast in both physical and biological aspects. The macrofauna formed a single community unit that showed signs of migrating on and off the beach with the seasons. Comparing the long-term changes that occurred from 1976 to 1981 (5 years), there were no substantial changes in the carbonate or organic content of the sediments, or the grain-size distributions. The small differences observed from 1976 to 1981 in the physical environment were well within the range of natural variation that open coast systems experience. In the macrobenthic community the dominant species were identical from 1976 to 1981. The only long-term differences were found in the occurrence of the rare species. Differences observed in the abundance of species were all within natural population variations. There are no changes in the physical or biological nature of the study area that could be attributed to the FRF pier. The fauna present (1981 conditions) were typical for a high energy ocean beach and the data collected did not exhibit any effect of the pier on the beach. 2. Sound Beach. The sound beach environment was found to be biologically similar to other low salinity estuarine habitats along the east coast. The macrofauna community gradually changed throughout the course of the study in response to the increasing salinity (from 3 to 8 parts per thousand) over the year. Salinity was the only physical variable measured that changed significantly throughout the study. During any one season there appeared to be a single community present. Abundances of individuals on transect IV were generally higher than the other two transects, but the species were the same. Higher abundances may be attributed to either the relic marsh or the nearby existing marsh or both. 44 In comparing the long-term changes that occurred from 1976 to 1981 (5 years) the major change in the physical environment was the salinity. Other changes in the sediments and depths were difficult to quantify and probably did not have any biological significance. Despite the fact that a marsh was present at transect IV in 1976 and had receded by 1981, there was no change in the organic content of the sediments from 1976 to 1981. In the macrofauna community there were changes in the dominant species from 1976 to 1981. The amphipod Monoculodes sp. was dominant in 1976, but not in 1981. The polychaete Laeonereis culvert was dominant in 1981, but not in 1976. Among the less common species there were more changes with several not occurring in the 1976 and the 1981 collections. The community structure measures for both years were about the same and do not reflect any of the changes that occurred at the species level. Overall, the changes observed in the macrofauna over the 5 years were related to the increased salinity in 1981. 3. Sample Design. The sample design employed in this study and by Matta (1977) was identical. This allowed for the best comparison of conditions through time at the selected transect locations. Considering the physically controlled nature of both the ocean and sound beaches, any environmental impact that could be detected by fixed, widely spaced transects would have to be large and widespread. Thus, fixed transects would likely not detect any changes that were very localized. Most importantly, in physically controlled environments the impact has to be very severe (with the possible exception of toxic substances, which are not at issue here) in order to be detected in the background noise of high natural variability that the physical environment imparts to the fauna. On the ocean beach, considering the biology and physical environment, it is unlikely that any reasonably executable sampling scheme could be developed to detect the pier effects at the site sampled in the intertidal and subtidal (out to 60 meters) beach. Any effects of the pier are far overshadowed by changes in the wave climate. On the sound beach, salinity is the main factor controlling the biological community and, in order to understand the changes in the community, salinity changes have to be incorporated into the sampling design. This could be accomplished by more frequent sampling. Should a major impact occur in either the sound or ocean beaches, the transects as established would provide the necessary background data for assessing the impact. They also give useful detail on the long-term variation of the two systems. 45 VI. CONCLUSIONS 1. Ocean Beach. No changes in the physical or biological environment from 1976 to 1981 could be attributed to the pier. Any differences documented were well within the natural variability that ocean beaches experience. Considering this large natural variability, it does not seem that a reasonably executable sampling scheme could be developed to find the pier effects in the intertidal or subtidal beach. 2. Sound Beach. Salinity in 1981 was higher than in 1976. This increase in salinity caused most of the changes in the macrofauna. There were no noticeable effects of the marsh on any transect, except transect IV, which generally had higher numbers of individuals than the other two transects. Considering the fluctuating nature of salinity, any future monitoring of the sound beach should include consideration of a long-term salinity record. 46 LITERATURE CITED BOESCH, D.F., "A New Look at the Zonation of Benthos Along the Estuarine Gradient ," Eeology of Marine Benthos, B.C. Coull, ed., University of South Carolina Press, Columbia, S.C., 1977, pp. 245-266. BOESCH, D.F., "Application of Numerical Classification in Ecological Investigations of Water Pollution," Eeology Research Sertes, EPA, 600/3-77-033, 1977. BOESCH, D.F., "Species Diversity of Marine Macrobenthos in the Virginia Area," Chesapeake Setence, Vol. 13, 1972, pp. 206-211. BOWMAN, M.L., "The Relationship of Emerita talpotda to Beach Characteristics," M.S. Thesis, University of Virginia, Charlottesville, Va., 1982. BRINKHURST, R.O., and COOK, D.G., "Aquatic Earthworms (Annelida: Oligochaeta) ," Pollution Ecology of Freshwater Invertebrates, C.W. Hart and S.L.H. Fuller, eds., Academic Press, New York, 1974, pp. 143-156. CARVER, R.E., Procedures tn Sedimentary Petrology, Wiley-Interscience, New Yorks LO COX, J.L., "Sampling Variation in Sandy Beach Littoral and Nearshore Meiofauna and Macrofauna,"' TP-14, U.S. Army, Corps of Engineers, Coastal Engineering Research Center, Fort Belvoir, Va., Sept. 1976. CROKER, R.A., 'Macro-infauna of Northern New England Marine Sand: Long-term Intertidal Community Structure," Ecology of Marine Benthos, B.C. Coull, ed., University of South Carolina Press, Columbia, S.C., 1967, pp. 439- 450. DAHL, E.,"Ecology and Zonation of Fauna of Sand Beaches!' Oikos, Vol. 4, IWO52= joe! WkoA7/e DEXTER, D.M., ''Comparison of the Community Structure in a Pacific and an Atlantic Panamanian Sandy-beach," Bulletin of Marine Setence, Vol. 22, 1972, pp. 449-462. DEXTER, D.M., ''Sandy-beach Fauna of Pacific and Atlantic Coasts of Costa Rica and Columbia," Revue Btology Tropics, Vol. 22, 1974, pp. 51-66. DEXTER, D.M., "The Sandy-beach Fauna of Mexico,'' Southwest, Wature, Vol. 20, 1976, pp. 479-485. DIAZ, H., "The Mole Crab Emerita talpotda (Say): A Case of Changing Life History Pattern,"' Ecological Monographs, Vol. 50, 1980, pp. 437-456. DIAZ, R.J., "The Effects of Pollution on Benthic Communities in the Tidal James River, Virginia," Ph.D. Dissertation, University of Virginia, Charlottesville, Va., 1977. 47 DIAZ, R.J., "Ecology of Tidal Freshwater and Estuarine Tubificidae (Oligochaeta) ," Aquatte Oltgochaeta Biology, R.D. Brinkhurst and D.G. Cook, eds., Plenum Publishing Corp., New York, 1980, pp. 319-330. EDGREN, R.A., 'Coquinas (Donax vartabilts) on a Florida Beach," Ecology , Vol. 40, 1959, pp. 498-502. FOLK, R.L., Petrology of Sedimentary Rocks, Hemphill, Austin, Tex., 1968. HOLLAND, A.F., and DEAN, J.M., "The Community Biology of Intertidal Macrofauna Inhabiting Sandbars in the North Inlet Area of South Carolina, U.S.A.," Ecology of Martine Benthos, B.C. Coull, ed., University of South Carolina Press, Columbia, S.C., 1977, pp. 423-438. KENNEDY, C.R.,''The Life History of Limodrilus hoffmeistert Clap. (Oligochaeta: Tubificidae) and Its Adaptive Significance!' Oikos, Vol. 17, 1966, pp. 158-168. KNOTT, D.M., CALDER, D.R., and VAN DOLAH, R.F., "Macrobenthos of Sandy Beach and Nearshore Environments at Murrells Inlet, South Carolina, U.S.A.," unpublished manuscript, 1982. LEPPAKOSKI, E.,''Assessment of Degree of Pollution on the Basis of Macrozoobenthos in Marine and Brackish Water Environments }' Academy Aboensts, Series B, Vol. 35, 1975, pp. 1-90. MATTA, J.F., "Beach Fauna Study of the CERC Field Research Facility, Duck, North Carolina,'' MR 77-6, U.S. Army, Corps of Engineers, Coastal Engineering Research Center, Fort Belvoir, Va., Apr. 1977. MIKKELSEN, P.S., ''A Comparison of Two Florida Populations of the Coquina Clam, Donax vartabtlis, Say, 1822," Veltger, Vol. 23, 1981, pp. 230-239. PEARSE, A.S., HUMM, H.J., and WARTON, G.W., "Ecology of Sand Beaches at Beaufort, North Carolina," Eeologteal Monographs, Vol. 12, 1942, pp. 135-190. ROBACK, S.S., "Insects (Arthropoda: Insecta) ,"" Pollution Ecology of Freshwater Invertebrates, C.W. Hart, Jr. and S.L.H. Fuller, eds., Academic Press, New York, 1974, pp. 313-376. SHELTON, C.R., and ROBERTSON, P.B., "Community Structure of Intertidal Macrofauna on Two Surf-Exposed Texas Sandy Beaches," Bulletin of Marine Setence, Vol. 31, 1981, pp. 833-842. TENORE, K.R., "The Macrobenthos of the Pamlico River Estuary, North Carolina," Ecologtcal Monographs, Vol. 42, 1972, pp. 51-69. 48 @I-c8 ° ou amy /cn* £07@OL *ZI-Z8 cou f£((*S°N) JaqueD Yoreassy BuylesuTsuq Teqyseoj) 3iodel snosueT{Te9STW :seTzes “AI °*(°S°N) Jajue9 yoieesoy BuTAsveuTsuy [eyseop *TII “Lr ‘staetTvyed “II *OTITL “I ‘“Saetd *€ «“eUTTOIeD YIION SHONG °*Z “eUNeZ YyoRag °*T *(uaxe} 219M APTS puNnos 9y} UO sUOTIeIS ANOF-AQuaM} pue eptsuess0 ay} uo suoT}e3s auo—AjuUeM. Worzy setTdwes) eutfoie9 yqaaion ‘yong qe aetd AATTTOeY yoAeassay PTety S,jequag yoressoy SutTiseutsuq Teqyseoy ay. 07 Jueoelfpe euney yoeoq ayq ut sasueyo W194-2u0T ay JO uoTIeSTASeAUT Ue JO Sji[NSeI saptAojad jaoday «°Z86T IeqWeAoN,, *8TITI 1AaA0D (71-78 *ou £ Jequeg yoIessay BuyiseuTsuyg Teqyseopn / yiodei snosueTTeosTW)--*wo gz ‘ “TTT °d [gy] “7861 “SIIN Worz eTqeTTeae : °eA “SpTeTyButads ‘azaqueaQ yoiesssy BuyiseutTsuyq Teqyseo) ‘sisvsauTsuy jo sdiop ‘Awry *S°n : “eA SATOATEG JAO¥--STISITYEd “*“L°f pue zetq “ry fq / eutyTore9 yuION ‘SyONG Je eunez yoeeq ut seZueyo wW19e3q-Bu0] “ru “zeta c1-28 °ou amy /¢n* €072OL 71-78 °ou £((*°S°n) Jequeg yo1eessy BupTIseutTsuq Te3seo)) Jiodai snosueTTeo9sTW :seTies “AI °(°S°N) Jaques yoIeessay BuTissuypsZuq Teyseop “III “Lr ‘SstseatTvyed “II °OTITL ‘Il «“Saetd *€ “eUTTOAeD YIION ‘HONG *Z “eUNey YyoRag °“T *(uayxeJ 91eM apts punos 9yW UO suUOTIeIS ANOJ-AQuUIMQ pue eptsues.0 ay} uo suoT je IS |UO-AjUeM] Woy saTdwes) euT[oIeD YqION ‘yONG Je JatTd AATT Toe, yoieessy PTety s,jequea yo1eesoay SuyiseutTsuq Teqseoy ayy 0} Queoelpe eunez yoeaq oy. uT seZueyo W194-Bu0T ay} JO uot eBTAseaAuT ue FO SqTNsed saptaoiad jaoday «861 TEequeAON,, °8T3T2 IsA0D (ZI-Z8 *ou £ azequag yoIeessy BuTiseutTZuq Teqseog / jiodei snosaueT{eosTW)--"wo gz { *TTE “d [gy] °7861 “SIIN Worz eTqeTTeae : eA SpTeTyBZutads ‘iequep yoiessay ButiseutTsuy [eqseo) ‘sadouTsuq Jo sdiop ‘Away *S°n : *eA SATOATOG 310qg--STIJeqTVed “L°f pue zetd “ry hq / eutyoiej yqION ‘HONG Je eunez yoeaq ut sasueyo wW19q-3u07 OP, SADA (NEY ZN amqT/cn* £0201 *7I-Z8 *ou S((*S*N) 1eqUueD YoIPessy Suyieeutsug Te seo)) Aiodei snoaueTTedsTW :seties “AI *(*S'n) Jajue) yoieessy BSuyiseuzZuq Teyseo) “TII ‘Lr ‘staeqtved ‘II “OTJEL “1 “Sietd *€ “eUTTOIeD YAION ‘yONG *Z “euNez Yyorog *T *(ueyxe] Bem apts punos ayj uo suOTIeAS ANOFZ-AQUaMy pue aptsueesco ay uo suoTjeqs aU0-AAQUAaM] wWoiz setTdmes) eutjTore9 yaIoN SyONG Je JeTd AQTT POR, yoAeassy pTety s,jaqueg yoieaseay suTieeutsuqg [e3seoD) ay} 07 Quadefpe euney yoeaq ayq ut sasueyo W19a}-SuoT ay} JO uotjesTysoeauT ue jo sj[nser saptaoad j10day «C861 TeqUeAON,, *9TITI 1eA09 (Z1-Z8 *ou £ Jaque9g Yyo1essoy SuTiseutsuq Te3seo) / y1ode1 snosueTTeostTW)--°wo gz { “TIT °d [gy] °7861 ‘SILIN Worz oTqeTTeae : °eA SpTetyButadg ‘aequeg yoieesoy BSuyiseutSuy [Teqseop ‘siseuT3uq jo sdiop ‘Away °S*n : *eA SAFOATOEG JIOJ--STASITVEC *L°r pue zetd “rey hq / eutptoie9 yzION ‘HONG Je euNezZ yoeaq ut sesueyo w1aq-Bu0y] “cou ‘zetd cI-cB °ou amqT/cn° £072OL °*ZI-ZB8 *ou £((°S°N) Jequep yoreasay Suyiseuzsuq Tejseo)) Jiodai snosue{Te9sTW :seTies “AI °*(°S°N) Jaque Yyoieessy BuyiseuTsuy Teqyseop “III “Lr ‘stseqtved “II "OTATL *I1 «°SdeTd °€ “*eUTTOIeD YIION “HONG *Z “teuNezZ YyoReg °T *(uayxe] 91am apts punos s9yq uo suOoyt}eqS ANOFZ-AQUMQ pue apTsueecs0 ay} uo suotjeqs suo-AjUeM} WoIZ satdwes) euyzjfoieg yqIoN ‘HONG Je aaetd ATT POR, yoAeessy pTetTy S$,jeque yoreesey SuyTieeutsuq Teqyseog ay} 03 Queodefpe euneyz yoreq oy. ut sazueyo W194-Bu0T ay} JO uot est AseAuT ue Jo sz[nse1 sapytaoid qaoday «C861 TEqWeAON,, *aTITI 1eA0D (ZI-Z8 *ou { taqueg yoreesey Suyisveuzsuq Teqyseog / yiodei snosue{Te9sTW)--°wo gz { “TIT *d [84] “7861 “‘SILN Worz oTqeTTeae : °eA SpTety3utidg ‘1aqua) yoleessy BuTissutTsuy Tejseop ‘siseuTsuq jo sdiop ‘kway *s*n : *eA S1FOATOG JIO™¥--STISITVEd “L°f pue zetd “ry hq / euzp~oie9 yzION ‘HONG 3e euNeyz YyoORaq uT saBsueyd wW194-3u0] “cou ‘zeta it i