ML20079N010

1988 Biological Monitoring Rept

ML20079N010
Person / Time
Site:	Brunswick
Issue date:	12/31/1988
From:	Benedict C, Blue R, Booth G CAROLINA POWER & LIGHT CO.
To:
References
RTR-NUREG-1437 AR, NUDOCS 9111110044
Download: ML20079N010 (81)

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$ BRUNSWICK STEAM ELECTRIC PLANT I

i 1988 Biological l Monitoring Report

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• BIOLOGY UtilT ENVIRONMEt4TAL SERVICES SECTION CP&L Carolitsa Power & Ught Company ESS RErTRENCE UBRARY 9111110044 001R31 PDa NUREO 1437 C PDR .

o I BRUNSWICK STEAM ELECTRIC PLANT 1988 BIOLOGICAL MONITORING RIPCRT Pr4 ared by:

l C. Benedict R. J. Blue Juvenile and Adult Impingement Editor I G. F. Rooth K. N. Cates Project Scientist Entrainment, Larval In,0ingement g D. S. Cooke -

River Larval Fish M A. B. Harris -

Statistics W. i. Herring -

Water Quality L. W,, Follard -

Marsh T. E. Thompson -

Report Compiler, Special Trawl Study Biology Unit Environmental Services Section 6

CAROLINA POWER & LIGHT COMPANY NEW HILL, NORTH CAROLINA March 1989 I Reviewed and Approved by:

a* I ~ Mh J. (va5' -

Principal Scientist Biology Unit I This report was prepared under my supervision and direction, and I accept full responsibility for its content.

-l 6Rtaa Manager k % lbJ.bsuu Environmental ServicesSection I

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, This copy of tte report 15 r<ot a controlled docueent as detailed in Environmental Services 1ection procccures. Any changes mece to the original of this report subsequen* to the date of Isswance can be obtelned from:

Vanspe (hvironmental Services Section Caroline Po.er & Light Ccepony

$he arc.) Harris Energy & Environmental Center Route 1, Boa 327 ,

New Hllt, North Carolina 27562

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l Acknowledgments i

The authors would like to thank many individuals who assisted i n collecting, identifying, and processing samples which marie this report possible. Thanks are extended to Debbie Calhoun, Della Lanier, Tina Reece, R. G. Sherfinski, and Ted Tyndall. Steve Parrish assisted in field collections as captain of the Pisces and constructed and maintained field and laboratory equipment.

Thanks also go to Kay Conaway who assisted with the data analyses for this report. A very special thanks to Susan Holth and to members of the Word Processing Subunit at the Shearen Harris Energy & Environmental Cen- ,

ter for assistance in typing this report. Sandra Price assisted with the

, completion of the figures appearing in this report.

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s Table of Contents Page f Acknowledgments..................................................... i L

List of Tab 1es...................................................... iii k List of figures..................................................... v

. Metric-English Conversion Tab 1e..................................... vi Common and Scientific Names Used in This Report..................... vii

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E x e cu t i v e S u m a ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

1.0 INTRODUCTION

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2.0 CAPE FEAR ESTUARY POPULATION H0NITORING...................... 2-1 2.1 Introduction............,.................................... 2-1 1 2.2 Methods...................................................... 2-1 2.2.1 Sample Co11ection............................................ 2-1 3 2.2.2 Data Analysis................................................ 2-2 l 2.3 Results and Discussion....................................... 2-4 2.3.1 Water Quality................................................ 2-4 2.3.2 Dominant Species............................................. 2-6 2.3.3 Seasonal Distribution........................................ 2-7 1 2.3.4 Spatial Distribution......................................... 2-8 2.3.5 Time-Series Analysis...........<............................. 2-10 l River Larval fish............................................ 2-10 B Marsh........................................................ 2-11 Alligator Creek ............................................. ~

2-11 Mott's Bay... ~.............................................. 2 12 l kalden Creek................................................. 2-12 Eld Head Creek.............................................. 2-13 2.4 funmary and Conclusions...................................... 2-13 3.0 PLANT-RELATED MONITORING PR0 GRAMS............................ 3-1 3.1 Introduction................................................. 3-1 l 3.2 Methods...................................................... 3-1 l 3.3 Results and Discussion....................................... 3-2 3.3.1 Dominant Species............................................. 3-2 3.3.2 Seasonality and Abendance.................................... 3-3 1 3.3.3 Entrainment Rates............................................ 3-4 3.3.4 Flow Rates................................................... 3-5 3.3.5 Fine-Mesh Screens............................................ 3-5 3.3.0 Survival Estimates........................................... 3-6 3.4 Summary and Conclusions...................................... 3-7

4.0 REFERENCES

................................................... 4-1 APPENDIX Special Trawl Study.......................................... A-1 ii

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I I List of Tables Table Page 1.1 The 1988 Brunswick Steam Electric Plant biolo monitoring program summary...................gical ................ 13 2.1 Annual mean density and the percentage of the total mean density for the most abundant taxa collected in the BSEP river larval fish program from 1983 through 1988........ 2-16 2.2 Total catch and percent total of the ten most abundant organisms collected in the BSEP marsh study during 1988...... 2-17 I 2.3 Annual catch-per-unit-effort by creek system for 13 selected speries in the BSEP marsh study during 1988......... 2-18 2.4 Time < cries analysis results for BSEP river larval fish data by station group indicatino trends in density from September 1976 through August 1988........................... 2-19 2.5 Time. series analysis results for BSEP marsh data by creek indicating trends in abundance from 1981 through 1988........ 2-20 3.1 Hean density and percent total of fish, penaeid shrimp, and portunid megalops entrained at the BSEP from Septembe' 1987 through December 1988.................... 3-9 3.2 Total larvae impinged at the BSEP during 1088, ranked by percent............................................ 3-9 L.3 Juvenile and adult impingement at the BSEP durin with compari sons to previous years. . . . . . . . . . ............. . . . .g 1988 3-10 3.4 Total jovenile and adult impingement catch per million cubic meters of water entrained and modal length for E selected species du-ing April, May, and June 1988 at 5 the BSEP..................................................... 3-11

a 3.5 Entrainment densities at the BSEP from September 1987 g through December 1988........................................ 3-12 i 3.6 Total number of selected species collected by trip in larval impingement at the BSEP during 1988................... 3-15 3.7- Entrainment rates at the BSEP from September 1987 through December 1988.............,.......................... 3-17 3.8 Mean dcqsity and percent total of fish, penaeid shrimp, and portunid megalops entrained at the BSEP from I

I September 1978 through December 1988......................... 3-E0 I 111 lI

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I listofTables(continuedl @ ,

l 3.9 Percent survival and number of impinged larval organisms returned alive, to the Cape fear Estcory during 1988.......... 3-21 g 3.10 Percent survival and number of juvenile and adult organisms returned alive to the Cape fear Estuary during slow-screen I ro t a t i o n i n 19 8 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-22 -

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I l f_i qu,r,e List of Figures Page 1.1 Location of fish dinrsicn structure, fish return system, and return bacin 4: the Brunswick Stearu Electric Plant....... 1-4 1.2 Brunswick Steam Electric Plant biologicti monitoring program sampling locations for 1988.......................... 1-5 I 2.1 Bottom salinity for selected stations in the Cape fear Estuary from September 1997 through December 1988....... 2-21 I 2.2 Hean daily freshwater inflow by month and mean bottom salinity at midriver Station 25 in the Cape Fear River from January 1985 through December 1988...................... 2-22 l 2.3 Bottem temperature for selected stations in the Cape feat Estuary from September 1987 through December 1988............ 2-23 I 2.4 Time-series analysis of total larval organism densities collected in Dutchman and Walden Creeks from 1979 through 1988................................................. 2-24 2.5 Time-series analysis of larval spot densities collected in the lower and upper areas of the Cape fear Estuary from 1977 through 1988............................................ 2-25 2.6 Time-series analysis of larval Atlantic menhaden densities collected in the lower area of the Cape Fear Estuary and Walden Creek from 1977 through 1988.......................... 2-26 2.7 Time-series analysis of blue crab data collected in Alligator Creek by the marsh trawl from 1981 through 1988.... 2-27 2.8 Time-series analysis of blue crab data collected in Mott's Bay by the marsh trawl from 1981 through 1988................ 2-27 2.9 Time-series analysis of blue crab data collected in Walden Creek by the marsh trawl from 1981 through 1988....... 2-28 2.10 Time-series analysis of white mullet data collected in Bald Head Creek by the marsh trawl from 1981 through l um 1988......................................................... 2-28 i g 3.1 brunswick Steam Electric Plant intake, discharge, diversion structure, and return system with associated effer 2 on fish.............................. ....................... 3-23 3.2 Mean monthly flow of water pumped at the BSEP from 1977 through 1982, 1987, and 1988................................. 3-24 l

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l Metric-English Conversion Table Ler,qth 1 micron (um) = 4.0 x 10-5 inch 1 millimeter (mm) = 1000 am = 0.04 inch I centimeter (cm) = 10 m = C.4 inch 1 meter (m) = 100 cm = 3.28 feet I kilometer (km) = 1000 m = 0.62 mile I Area 2

1squaremeter(m)=10.76squarefeet I hectare = 10,000 m2 = 2.4/ acres Waight I 1 microgram (ug) = 10-3 mg or 10-6 g = 3.5 x 10-8 ounce 1 milligram (mg) = 3.5 x 10-5 ounce 1 gram (g) = 1000 mg = 0.035 ounce i kilogram (kg) = 1000 c = 2.2 pounds 1 metric ton = 1000 kg = 1.1 tons 1 kg/ hectare = 0.89 pound / acre I

Volume 1 milliliter (ml) = 0.034 fluid ounce 1 liter = 1000 ml = 0.26 gallon Temperature i

Degrees Celsius ('C) = 5/9 (*F - 32) l ,

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Comon and Scientific Names Used in This Report r

American eel Anguilla rostrata r Atlantic menhaden Brevoortia tyrannus L Anchovies Anchoa spp. (all sizes combined)

Anchovy Anchoa spp. (> 13 mm)

Striped anchovy A. hepu tus j Bay t,nchovy A. mitchfill E Humichog Fundulus heteroclitus Silversides Atherinidae Atlantic silverside Afenidia menidia Pipefish Sygnathus spp.

Crevalle jack Caran: hippos Seatrout Cynosefon spp.

Weakfish C. regalis Spot Leiostomus xanthurus l Croaker AfIcropogonias undulatus P1ntish Lagodon rhomboldes Mullet I Striped mullet Afugli spp.

Af. cephalus White mullet Af. curema l Blennies Gobies Blennidae Gobiidae Naked goby Gobiosoma bosci I Searobin Fringed flounder Prionotes spp.

Etropus crossotus Flounder I Southern flounder Paralfchthys spp.

P. lethostigma Tonguefish Symphurus spp.

l Blackcheek tonguefish Shrimp S. plagfusa Penaeus spp.

g Brown shrimp P. aztecus 3 Pink *hrimp P. duorarum White shrimp P. settferus Psrdback shrimp I Grass shrimp Trachypeneus constrfetus Palaemonetes spp.

Blue crabs Callinectes spp.

Blue crab C. sapidus Lesser blue crab C. simitus vii

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SUMMARY

Biological monitoring was conducted during 1988 in the Cape fear I Estuary near Carolina Power & Light Company's Brunswick Steam Electric l

Plant. Comparisons of the results of this monitoring aere made to results from previous years with long-term trends discussed.

l Data collected during 1988 on the various stages of fish and shell-fish populations in the estuary indicated little change in species compo-sition or the seasonality of organisms compared to previous years.

Anchovies dominated the river larval fish samples and spot dominated the I marsh samples. Discrete groups of organisms were prevalent in the estuary with regard to winter-spring and summer-f all time periods as in previcus years. Environmental factors, particularly freshwater inflow, signifi-cantly influenced the distribution and abundance of individual species.

Densities of total larval organisms in the river and Walden Creek have not changed significantly over the past 11 years. Populations of juvenile organisms in Walden Creek have either not changed significantly or have increased over the past eight years. These trends indicate that operation of the Brunswick Steam Electric Plant has not adversely impacted the I nursery populations in Walden Creek even though it is in close proximity to the intake canal. Relatively low freshwater inflow during 1988 resulted in higher abundances of some species in the upper estuary.

Higher abundances of some species in the upper estuary indicated that operation of the Brunswick Steam Electric Plant did not prevent mevement to this area.

Plant intake modifications remained effective in reducing its es due to impingement and entrainment. The diversion structure excluded most I large organisms from the intake canal causing a reduction in the impinge-ment of large indivicuals. The protection of these individuals was impor-tant because they had survived life stages with high mortality rates and I ,

were the reproducing members of their respective populations. More water was used for condenser cooling in 1988 compared to the previous year; however, entrainment of larval organisms was reduced as a result of fine-mesh screens. Larval organisms that would have been entrained before the I viii I

I installation of fine-mesh screens were returned to the est*ry via the return system. Survival' study results indicated that substr cial numbers of fish and shellfish were returned alive to the estuary.

Operation of the Brunswick Steam Electric Plai.t during 1988 did not affect the species composition, abundance, seasonality, or distribution of fish and shellfish in the estuary. Environmental f actors have been and continue to be the dominant force influencing the organisms in the Cape fear Estuary.

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1.0 INTRODUCTION

I Carolina Power & Light Company (CP&L) was issued a permit in Jan-uary 1981 to discharge cooling water from the Brunswick Steam Electric Plant (BSEP) into the Atlantic Ocean under the National Pollutant Dit-charge Elimination System (NPDES). Cooling water is drawn from the Cape Tear River (CFR). As a stipulation of the NPDES permit, biological mon-l itoring was conducted to provide sufficient information for a continuing assessment of power plant impact on the Cape fear Estuary (CFE) with par-ticular emphasis on the marine and estuarine fisheries. With some modift-cation, this biological monitoring requirement was a continuation of research conducted on the CFE by various investigators since 1976 I (CP&L198Sa).

Another NPDES permit stipulation was installation of plant intake modifications to reduce entrainment and impingement of estuarine organ-isms. A permanent diversion structure was constructed across the mouth of the intake canal in November 1982 to reduce impingement by preventing large fish and shellfish from entering the canal (Figure 1.1). A third fine-mesh (1-mm) screen was installed on each unit in April 1987 to reduce entrainment. Thus, three of the four intake traveling screen assemblies I on each unit were covered with fine-mesh screens.

A maximum flow of 922 cubic feet per second (cfs) (26.1 cubic meters per second [ cms]) per unit is allowed from December through March, while during the period from April through November, 1105 cfs (31.1 cms) per unit is allowed. Intake cooling water continuously flows through fine-mesh screens during these periods. The flow of one unit may be increased to 1230 cfs (34.8 cms) resulting in use of a fourth intake pump operatil.g without fine-mesh screens during July, August, and September.

Data collected during 1988 were compared to data from previous years to examine long-term populatien trends' (CP&L 1980, 1982, 1983, 1984, 1985a, 1985b, 1986, 1987, 1988) . The 1988 biological monitoring program l contained several changes compared to previous years (Table 1.1). The nekton program and four marsh seine stations were discontinued in order to I 1-1 I

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streamline the overall monitoring program. In addition to the monitoring program, a special trawl study was conducted to better evaluate the l

factors which govern recruitment of organisms to the nursery areas upriver from the BSEP.

The BSEP biological monitoring program was designed to address ques-tions relating to the fisheries populations of the CFC and associated environmental variables (Section 2.0 and Appendix). Plant-rehtea pro-grens (Section 3.0) addressed questions concerning intake modifications te reduce entrainment and impingement.

l Sampling locations ranged from Dutchman and Bald Head Creeks to Alli-gator Creek adjacent to Wilmington, North Carolina (figure 1.2). Because l

several stations were sampled in each creck in the marsh program, the entire creek was designated as a sempling area.

Periods for which 1988 data are reported vary by study. T ht. river larval fish study data were collected from September 1987 through August 1988 to correspond to periods of larval recruitment. The marsh and impingement studies data were collected from January through Decem-ber 1988. Data for water quality and entrainment studies were collected from September 1987 through December 1988.

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I I Table 1.1 The 1988 Brunswick Steam Electric Plant biological monitoring program summary, Program frequency locations l Water quality Once per week 11, 15, 19, 24, 25, 29, 35, 38, 42 I River larval fish Twice per calendar 11, 18, 24, 25, 34, 37 I month 41 Marsh Seine Once every three weeks 16, 25 Trawl Once every three weeks 11, 15, 17, 21, 24, 27, l 28, 31, 32, 42, 43, 51 I Entrainment Four times per calendar Discharge weir month Impingement Juvenile and adult Twice per calendar month Fish return fiume month l Larval four times per calendar month Fish return fiume I

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[ su 440cnEU Figure 1.2 Brunswick Steam Electric Plant biological rnonitoring program sampling locations for 1988.

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2.0 CAPE FEAR ESTUARY POPULATION MONITORING t

2.1 Introduction Estuaries are important because approximately 93% of the East Coast's commercial fish, shellfish, and sport fish spend some portien of their lives in this ecosystem (McHugh 1967). The fisheries population of the l CTE was examined in 1988 to determine if operation of the BSEP had an adverse impact on these populations. The river larval fish study was designed to determine transportation of larvae into the estuary, while the marsh program was designed to determine successf;1 recruitment of post-larvae to the nursery areas. The associated hydrographic conditicns that control many of these movements were regularly monitored in the aater quality study. The estuarine monitoring program was oes;7ned to examine:

1. Freshwater inflow, temperature, and salinity flectuation.

2. Species compcsition.

3. Seasonal dis +.ribution of species.

4. Spatial distr;bution of species.

5. Relative yearly species abundance.

6. Long-term trends in species pcpulations.

Data from 1988 were compared with data from previous years to qucnt-ify changes in the numbers of organisms utilizing the CFE that were sus-ceptible to " cropping" by cperation of the BSEP. Population trends in Walden Creek were of particular interest because of Walden Creek's close l proximity to the intake canal.

l 2.2 Methods 2.2.1 Sample Collection Nine water quality stations have been sampled once per week since 1982. Surf ace and bottom temperatures and salinities were measured in degrees Celsius ('C) and in parts per thousand (ppt), respectively.

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l I Simultaneous replicate river larval fish samples were collected at night from the surface and 'oottom at each of seven stations once every two weeks (Figure 1.2). Five stations were located in the CFR channel and one each in Dutchman and Walden Creets. A 1-m diameter 505-um mesh net and a flowmeter were attached to each of four rectangular fr nes (Hodson et al.

1961). One of the two replicate surface and bottom samples from each sta-tion was processed (CP&L 1987). Stations and gears have not changed since 1981(CP&L1952).

The sampling gear (3.2-m trawl and 15.2-m seine), sampling methods, cnd hboratory procedures for the marsh program were identical to those used in orevious years (CP&L 1988). Trawl sampling locations were ident-ical to those in 1987 (Figure ..?). inree stations were located in Bald l

Head Creek, four in Walden Creek, two each in Mott's Bay and Alligator Creek, and one in the return basin.

The selection of marsh sampling locations was based on different salinity regimes typically present in the CFE. Said Head Creek is located in the polyhalir.e (18.0-30.0 ppt salinity) 2cne of tne estuary adjacent to the mouth of tre CFR (Figure 1.2). Walden Creek is located in the mesoba-line (5.018.0 ppt salinity) zone of the estuary near the BSEP intake canal. "mt'; Fay is an oligohaline (0.5-5.0 ppt salinity) to masohaline l

area well ipriver from the BSEP. Alligator Creek is the uppermost creek 3 system studied and 11 located in the head of the estuary where the salin- E ity regime is usually fresh to oligohaline.

2.2.2 Dat Analysis Bottom salinity and temperature values were plotted for stations I

characteristic of the va. ious salinity regimes in the CFR chanr.el and for three creek systens. The downriver station (15) was located near the mouth of the river, the midriver station (29) was in the vicinity of Sunny Point, and the upriver station (42) was approximately 17 kilometers north of 'he plant (Figure 1.2). One station from the middle of Bald Head, g Walden, and Alligator Creeks was plotted for comparison. Total freshwater W inflow was derived from formulas combining discharges from three United I

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States Geological Survey stream-gaging stations with estimates of runoff from ungaged areas just upst*eam and adjacent to the estuary (Glese et al.

1979,1985). Geged areas represent 73% of the total drainage area for the CFE (Giese et al. 1985).

I Biological data were collected and evaluated by three criteria:

species composition, location, and time. The data were summed over one or more of these criteria and a mean was calculated to represent the values. Densities of larval organisms were computed by dividing the num-ber of. collected organisms by the volume of water filtered and then multi-plying by 1000 to obtain number collected per 1000 m3 . The catch-per-unit-effort (CPUE) of juvenile organisms was calculated by dividing ihe total number of collected organisns by the nuber of trawl or seine 3

samples collected in each creek.

Time-series analyses were performed on river larval fish and marsh

, data (CP&L 1985a). Since the, distribution of numbers at any level tends to be skewed toward the low range of values, the loge (X + 1) transforma-tion of the individual samples was uscd to normalize the data prior to performing time-series analysis. The year-level terms in the time-series model serve as indications of yearly abundance after adjusting for envi-ronmental effects which impose selective periodicities on the distribution of organisms. Statistical testing for the presence or absence of signifi-cant periodicity within and among years provided an evaluation of model fit and. a testable method of biological or environmental interpretation.

Significance of the upward or downward trends was determined at the P $ 0.05 level. The coefficient of determination (R2 ) was used to indi-cate how well tne model explained the variability in the data.

River larval fish data were analyzed from September 1976 through August 1988 except for total crganisms which were analyzed from

September 1978 through August 1988. The marsh data were analyzed from January 1981 through December 1988. Occasionally time-ceries analysis could'not be used due to no catches of a particular species in some years or when the model failed to account for significant periodicities. In these situations, the mean loge (CPUE + 1) was used to compare popula-k tions.

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Spatial differences of larvae were determined by comparing time-series year-level terms - from Station 11 (Dutchman Creek) to Station 24

, (Walden Creek). Dutchman Creek is downriver and away from the direct in-fluence of the plant and serves as a control for Walden Creek which is located in the vicinity of the intake canal (Figure 1.2). Comparisons were also made between lower-estuary (average of Stations 12, 25, 37) and upper-estuary (average of Stati ns 34, 41) year-level terms. Spatial differences of organisms residing in the marshes were determined by comparing mean CPUE between the different creeks and the return basin.

Seasonal and spatial distributions and trends were bared on data collected by the gear (trawl or seine) deemed most effective for catching each species.

Recruitment periods of organisms to the marshes were determined by examining the CPUE and length-frequency distributions of each species by creek. Shrimp smaller than 21 mm and blue crabs smaller than 11 mm were identified only to genus and family, respectively, due to difficulties in accurately identifying organisms of this size to lower taxonomic levels.

2.3 Results and Discussion l 2.3.1 Water Quality I

E Salinity in the CFE typically exhioits a decline during the winter months and an increase from e'ely spring through late summer. This trend results from increased freshwater inflow during the winter followed by 1aduced inflows during the summer. Short-term decreases in salinity are E

sometimes observed during the late summer and early fall, typically a E period of high salinity. These decreases are the result of weather disturbances (resulting in increased rainfall) passing over the Cape Fear watershed. These disturbances are normally short in duration and salinity increases tc previous levels. Variations in freshwater inflow may shift salinity zonts throughout the estuary.

Salinity began to decrease during November 1987 (Fiaures 2.1 and 2.2). The decrease continued into February 1988, following the typical 2-4 l

I patterns in the CFR for that time of year. The increased freshwater inflow during early 1988 gradually subsided allowing salinity levels to rise well into midsummer. During August a sharp drop in salinity was I noted in the creek and river stations (Figure 2.1). This decrease was most likely a ressit of local precipitation. However, in September and November, two more salinity declines were observed. These occurrences resulted from a brief increase in freshwater inflow to the CFE (Fig-ure 2.2).

Average yearly freshwater inflow decreased by approximately 50% each year from 1984 through 1986 then increased to a level comparable to 1984 during 1987. Freshwater inflow again decreased by about 50% in 1988:

Year Daily average freshwater inficw (CMS) 1984 369 l 1985 1986 183 95 1987 337 1988 153 I The CFE exhibited typical seasonal variations in temperature during the yee" (Figure 2.3). A maximum temperature of 32.6'C was recorded dur-ing August in Bald Head Creek and a minimum temperature of 3.0'C was ob-served during January in both Bald Head and Walden Creeks.

lI l An outbreak of Gymnodinium spp. (red tide) occurred along the Nori.h l

Carolina coast during the fall of 1987 and the winter of 1988 (Bob Benton, pers. comm. , N.C. Department of Health Services, Division of Shellfish j- Sanitation). A maximum concentration of approximately 100,000 cells / liter was detected at the mouth of the CFR during the second week of December 1987. The organism was last detected on February 7, 1988.

i I

I 2-5

B 2.3.2 Dominant Species l

Seven fish taxa (anchovies, Gobiosoma spp., croaker, spot, silver-sides, Atlantic menhaden, and blennies), one shrimp genus (shrimp post-larvae consisting of Penaeusspp.), and one crab family (Portunidae) accounted for 94.9% of the larvae collected from the CFE in 1988. The most abundant taxa were similar to those of the previous five years (Table 2.1). Anchovies accounted for 50.6% of all larvae collected in 1988. Gobiosoma spp. densities increased in 1988 and accounted for 16.9%

of the total larval density. Croaker and spot densities accounted for 18.1% of all larvae collected in 1988 (Table 2.1).

Portunid crab megalops (primarily blue crab) accounted for 3.8% of the total larval density in 1988. The annual mean density of 83/1000 m 3 was a substantial decrease from the 1987 mean of 170/1000. m 3 (Table 2.1). However, fluctuations of over 50% annually are common in g

catches of blue crab and can result from variable temperature and salinity N patterns during recruitment (Leming and Johnson 1985).

Postlarval shrimp (brown, pink, and white) represented 3.6% of the I

total larval density in 1988 which was less than in 1987 due to reduced recruitment in the fall. Brown shrimp postlarvae usually enter the estu-ary from February through May, followed by pink and white shrimp from May E through October (Ccpeland et al. 1979). Therefore, the lower densities I were due mainly to reduced recruitment of pink and white shrimp.

Ten taxa comprised 96.5% of the total marsh trawl catch (Table 2.2). Spot was the numerically dominant organism collected, repre-senting 60.1% of the total catch. Grass shrimp, Atlantic menhaden, and bay anchovy comprised 24.3%, while the remaining 77 taxa made up 15.6% of the trawl catch. With the exception of pink shrimp and portunid crabs, l

the most abundant species collected in 1988 were the same as those col-1ected in 1987 (CP&L 1988). Hodson (1979); Huish and Geaghan (1979);

Weinstein (1979); and CP&L (1983,1984,1985a) also reported that catches in the CFE in past years were dominated by these species.

I 2-6 I

1 .

I l Ten species comprised 98.8% of the total marsh seine catch (Table 2.2). As in previous years, grass shrimp were numerically dominant J5 making up 50.3% of the total catch; while spot, Atlantic menhaden, and mummichog comprised another 42.4%. The remaining 29 taxa comprised 7.3%

of the total seine catch. With the exception of pinfish, the ten dominant species in 1988 were the same as in 1987 (CP&L 1988) and were similar to those collected in previous studies by Weinstein (1979) and CP&L (1983, I 1984,1985a). Thirty-three taxa were t.ollected in 1988 compared to sixty-five in 1987 (CP&L 1988). This was probably a result of reduced sampling effort which limited the number of different habitats sampled.

2.3.3 Seasonal Distribution I The seasonal distribution of many estuarine species is associated with recruitment of individual species. Increases in number and decreases in mean size are indicative of major recruitment periods of most species. Generally after recruitment ceases, an increase in mean size and a decrease in number occurs. During the subsequent several-month resi-dence and growth period, most species decline in number due to emigration and natural mortality.

I The seasonal and size distributions of selected species collected in 1988 followed these patterns Seasonal trendr -f selected species of larvae in the CFE during 1988 at each group of stations were similar to those occurring over the past 10 years:

Spot December through May Croaker October through April Portunid megalops August through December Flounder December through March Striped mallet December through March Atlantic menhaden February through May I Penaeid postlarval shrimp brovn February through May pink and white -

May through October Anchovies April through October Seatrout I Cobiosoma spp.

May through October May through October 2-7

T ,

I Abundance of Atlantic menhaden, spot, and southern flounder in the marshes peaked in the late winter and early spring. The 1987 recruitment of croaker to the marshes began in the fall of 1987 and peaked the follow-ing winter and spring. Portunid crab megalops recruitment to the estuary was during the fall of 1987 and 1988. Recruitment of young-of-year blue crab increased during the spring of 1988 following the respective mega-lopal recruitments. Brown shrimp, striped mullet, mummichog, Atlantic B

silversides, and white mullet were most abundant from spring through early a summer. The abundance of bay anchovy peaked in late summer. Pink shrimp and white shrimp reached their maximum numbers in the summer and early fall. These periods of maximum abundance were similar to those observed by other investigators in previous years (Weinstein et al. 1980; Xneib 1984; CP&L 1984, 1985a, 1988) and corresponds to the 1988 river larval fish data.

2.3.4 Spatial Distribution The distribution of most estuarine species is dependent upon many variables inherent to estuaries. Among these variables are temperature (Joseph 1973), turbidity (Blaber and 81aber 1980; Miller et al. 1984),

food availability (Lasker 1975), predation (Weinstein et al. 1980; W61nstein and Walters 1981), salinity (Gunter 1961), freshwater inflow (Rogers et al.1984), and transport by currents (Pietrafesa et al.1986; E Boehlert and Mundy 1988; Lawler et al. 1988). Different species and/or different life stages of the same species may respond differently to these environmental variables (Miller 1985). Salinity, freshwater inflow, and water-current transport may be the most important variables in determining the utilization of a particular area in the CFE by migrating organisms.

Densities of most larval species were greater in the creeks than in the river channel. The year-level term for total organism density in Dutchman Creek was 6.98, while the year-level term for Walden Creek was 6.82 in 1988. The year-level term was 6.56 for the lower river stations and 6.3b for the upper river stations.

I 2-8 l

1 The species-area association was similar to that reported using a principal-component analysis in 1984 (CP&L 1985a). Densities of Atlantic menhaden and croaker larvae were highest in the upper river areas, while I other species were found in the high-salinity areas downriver.

Bald Head Creek is usually a polyhaline system which would support large populations of species such as Atlantic silverside, white mullet, l and pink shrimp (Weinstein 1979). The CPUE of organisms in the marshes indicated that Atlantic silverside and white mullet were most abundant in Bald Head Creck; however, pink shrimp were most numerous in the middle to upper estuary (Table 2.3).

I Walden Creek supported larger numbers of Atlantic menhaden, mummichog, spot, striped mullet, brcwn shrimp, and blue crab than the other natural creek systems. These species are typically associated with oligehaline and mesohaline water (Weinstein 1979) which occurred in Walden Creek during the respective recruitment periods of these species in 1988.

Mott's Bay is generally oligohaline to meschaline and occasionally approaches polyhaline conditions depending upon the magnitude of fresh-water inflow. Bay anchovy and pink shrimp populations were largest in I Mott's Bay. Bay anchovy is usually more abundant in the oligohaline and meschaline zones of the estuary (Jones et al. 1978). The relatively large number of pink shrimp in the upper estuary may have resulted from high salinities (low freshwater inflow) in this area (Figure 2.2) during late summer a'd fall which made this area suitable as a pink shrimp habitat (Deegan and Day 1984; CP&L 1986, 1987).

Croaker and southern flounder were the most abundant species col-lected in Alligator Creek. These species are usually found in oligoht.line I areas (Weinstein et al. 1980).

The return basin, located at the fiead of a tidal creek, was most likely populated with estuarine o. ganisms by a combination of natural immigration and the BSEP fish return system. De CPUE of Atla tic menhaden, spot, croaker, brown shrimp, pink shrimp, and blue crab was I 2-9

p I

higher in the rettrn basin than in any natural creek system (Table 2.3).

Comparisons between the t uurn basin and individual stations in Walden Creek indicated population abundances and seasonal distributions of most species were similar to or greater than those of the middle and upstream l

stations. These results indicated the return basin was being utilized by g

transient organisms in the same manner as other upstream nursery habitats and were similar to those observed in previous years (CP&L 1988). The relatively large number of croaker and southern flounder may indicate the successful return of these organisms alive to the CFE by the return system g

since these species usually prefer oligohaline conditions. Upper e-scha. E line conditions usually exist in the eturn basin.

2.3.5 Time-Series Analysis I

River Larval Fish Studies of fish eggs and larval transport from the ocean to estuaries were reviewed by Norcross and Shaw (1984). They concluded that some of g

the factors causing fluctuations in the mean density between years are E spawning success, transpcet mechanisms (wind and water current), water temperature, and salinity. Fluctuations in the mean density of larvae among years is a natural and expected occurrence. Therefore, long-term trends are more useful in population evaluations than year-to-year compar-1 sons. Time-series analysis was used to evaluate whether the annual abun-dance of a particular species increased or decreased significantly over time.

Time-series analysis results showed that the density of total larval organisms in the areas closest to or upstream of the influence of the BSEP intake canal (Walden Creek, the lower river, and the upper river stations) has not changed significantly during the past 10 years (Table 2.4).

During the same time period, the total pensity of organisms in Dutchman Creek, an area below the influence of the plant, has declined signifi-cantly. This decline in densities in Dutchman Creek was attributable pri-marily to declines in Gobicsoma spp., flounder, and spot censities.

Although decreases occurred over the entire study period, the year-level 2-10

I terms for Goblosoma spp. and spot were up in recent years, while the year-level term for flounder has declined:

.g a Dutchman Creek year-level terms Species Year 79 80 81 82 83 Ba 85 86 87 88 l Spot 1.87 1.87 1.52 2.02 2.01 1.93 1.46 1.22 1.56 1.64 Gobiosoma spp. 3.29 2.64 3.40 2.59 2.45 2.68 2.28 2.73 2.91 2.95 Flounder 0.91 0.41 0.73 0.91 1.01 0.66 0.50 0.30 0.61 0.40 Tht. seasonal occurrence of total organisms was very similar in both Outchman and Walden Creeks from 1979 through 1988 (Figure 2.4). Similar patterns of seasonal occurrence were evident for spot and Atlantic menhaden (figures 2.5 and 2.6). Even though the seasonal occurrence of larval species has been-very consistent, there have been fluctuations in the densities from year to year. Significant increases in the densities of larval croaker, Gobiosoma spp., Atlantic menhaden, mullet, and shrimp have occurred in Walden Creek (Table 2.4). A,nchovies, Gobiosoma spp. , and shrimp have also increased significantly in the lower and upper river stations.

Marsh Alligator Creek I The cbendances of croaker, spot, and flounder increased significantly in Alligator Creek since 1981 (Table 2.5). Although the abundance of blue crab decreased over the entire study period, the time-series year-level term increased in 1988 (Figure 2.7). The abundances of f. Q ntic menhaden fluctuated from 1981 through 1988; however, there was no sicaificant trend for the study period. The year-level term calculated t'or 1988 was the highest since 1982 indicating successful' recruitment and upper estuarine utilization. Time-series analysis could not be performed on brown, pink, and white shrimp data because none were collected in Alligator Creek dur-ing one or more years since 1981. Annual mean loge (CPUE+1) values I 2-11 I

i I

indicated that the brown shrimp population remained much smaller in 1988 than the 1985 and 1986 populations (CP&L 1988). Pink shrimp, as in the past, were collected in low numbers reflecting a preference for more saline waters. No white shrimp were collected in Alligator Creek in 1988 af ter relatively large catches in 1986 and 1987 (CP&L 1988). This was probsbly due to poor recruitment to the estuary in 1988 compared to 1987 as documented by the river larval fish program (Table 2.1).

Mott's Bay Fluctuations in abundance of most species in Mott's Bay were usually '

I caused by changes in fr9shwater inflow and salinity during their respec-tive recruitment periods. However, these changes in flow anJ salinity conditions have not resulted in any significant trends since 1981 with the exception of juvenile blue crab (Table 2.5). The abundance of juvenile blue crab was relatively stable from 1984 through 1986 but declined sharp-ly in 1987 and remained low in 1988, resulting in a significant decreasing trend (Figure 2.8). Analysis of river larval fish data showed that no significant trend in the abundance of portunid megalops has occurred since 1979. This indicated that larval blue crab migrated to the upper estuary but have not settled out in the Mott's Bay area in recent years.. White shrimp were not analyzed because none were caught in 1984 and the popu-lation remained small in.1988 (CP&L 1984, 1985b, 1987, 1988). E 5

Walden Creek Flounder and brown shrimp populations in Walden Creek have increased significantly since 1981 (Table 2.5). Relatively large numbers of flounder were recruited to Walden Creek during 1983,1984, and 1987 as 1.

result of high freshwater inflow (CP&L 1984, 1985b, 1988). Although freshwater inflows were not high during the 1988 recruitment, the salinity in Walden Creek was depressed, thus allowing flounder to again utilize Walden Creek in large numbers. The 1988 population of juvenile blue crab was larger than during the - previous three years; however, an overall y decreasing trend in abundance occurred over the entire study period (Fig- ~u ure 2.9). The population trends of spot, croaker, striped mullet, whi' I

2-12

I mullet, pink shrimp, and white shrimp have not changed significantly over the study period, although substantial fluctuations among years have oc-curred. Atlantic menhaden data could not be analyzed due to significant periodicities which were poorly accounted for by the time-series model.

However, the mean 1988 annual loge (CPUE+1) indicated that the CPUE was the largest since 1982. This increased CPUE, along with the significant increasing trend from 1981 to 1987 (CP&L 1988), indicated that Walden Creek was heavily utilized by this species.

Bald Head Creek Croaker and striped mullet data showed increasing trends in abundance I during the study period (hble 2.5). Both species decreased in number during 1985). This may have been a result of slightly higher salinity during recruitment in 1988 than during recruitment in 1987. The white mullet population decreased significantly over the study period (Fig-ure2.10). The populations of Atlantic menhaden, flounder, pink shrimp, and juvenile blue crab have fluctuated substantially among years but have not changed significantly during the study period. Time-series analysis could not be performed on spot, brown shrimp, and white shrimp data from l g 8ald Head Creek due to significant periodicities which could not be ac-l 5 counted for by the model or due to none being collected during a year.

) The 1988 aanual mean loge (CPUE+1) values indicated the population of

(- brown shrimp was the smallest since 1991 (CP&L 1988). No white shrimp l were collected in 1988. This decrease in white shrimp followed the largest catch of the study in 1987 (CP&L 1988). The population nf spct in Bald Head Creek in 1988 was the largest since the study began in 1981 and l followed a significant increase from 1981 through 1987 (CP&L 1988). This reflected th_e general increase throughout the estuary as evidenced by

-g increasing densities of larval recruits in the icwer river during 1988

E (Figure 2.5).

~

2.4 Summary and Conclusions i

l The species composi t ion and seasonal occurrence of larval fish, shrimp, and crabs er.tering the Cape Fear Estuary have changed very littic I 2-13

F during the past 11 years. Anchovy, Cobicsomu spp. , and crocker have dominated the river larval fish samples. The species composition and sea-sonal occurrence of juvenile organisms r1 siding in the marsh nursery areas also e.xhibited little change over the past eight years. Marsh trawl and' seine samples were dominated by spot and grass shrimp.

a The spatial distributions of larval fish and shellfish were similar to what has been reported historically. Densities of total larval or-ganisms were greater in the creeks than in the river channel. Densities of Atlantic menhaden and croaker larvae were highest in the upper estuary indicating that these ocean-spawned fish were able to move past the Brunswick Steam Electric Plant intake canal area during recruitment to the estuary. The distributions of juvenile fish and shellfish residing in the marsh nursery areas were influenced by changing freshwater inflow and E

salinity during their respective recruitment periods. Pink shrimp, his- 5 torically more abundant in Bald Head Creek, were most abundant in Walden Creek and Mott's Bay. Croaker and southern flounder were also most abun-dant in the marshes above Walden Creek past the influence of the intake canal. All other species were most abundant in Walden or Bald Head Creeks. The greater abundance of some species in Walden Creek compared to the other creeks indicated that operation of the Brunswick Plant did not -

prevent these organisms from using this nursery area as a result of its close proximity to the intake canal. g E

Overall trends in the abundant.e of larval anchovy, croaker, Geblosoma spp., and postlarval shrimp during the past 12 years have increased, while abundances of spot and flounder have decreased, possibly reflecting fluc-tuations in natural occurrences arid :stribution of larvae in the Cape Fear Estuary. The effects of spawning, ccean currents, predation, fresh-I water inf bw, and many cther factors affect the success of a species to prcduce sufficient offspring for future populations. Total larval organ-isms exhibited a nonsignificant trend in abundance in Walden Creek, while

! species such as croaker, Gobiosoma spp.', Atlantic menhaden, mullet, and l Peraeus spp, increased in abundance. Juvenile fish and shrimp residing in .

l the marshes exhibited nonsignificant or increasing trends in abundance over the past eight years. Blue crab decreased in abundance in all creeks

! 2-14 I

5

I studied with the exception of Bald Head Creek. These decreases were probably a result of natural variation since the densities of portunid megalops (larval blue crab) showed no significant trend over the study I period. No reductions in the abundances of total lervae or nursery popu-

, lations in Walden Creek or the upper estuarine areas (Mott's Bay and Alli-gator Creek) have occurred.

The return basin supported large numbers of many estuarine species.

The relative abur. dances and seasonal distributions of most selected spe-cies in the return basin were similar to those in upper and middle Walden Creek, indicating the basin was being utilized as a nursery habitat.

The association between trends in abundance and environmental vari-ables, as well as large populations of fish and shellfish in the vicinity of and upstream of the Brunswick Steam Electric Plant in'ake canal, indi-cated tha'. pepulations in the Cape Fear Estuary were dependent upon natural phenomena and were not adversely impacted by the Brunswick Steam Electric Plant.

LI I

I

.I I

.g .

I E-15 I

i l

\

Table 2.1 Annual mean density (organisms /10003m ) and the percentage of the total mean density for the most l

abundant taxa collected in the BSEP river larval fish program from 1983 through 1988 (based on ranking for the 1988 larval year).

1983 1984 1985 1986 1987 _ 1988 ,

Mean Mean Mean Mean Mean Mean Taxa density i density % density % density % density % density %

Anchovies 614 41.7 587 48.3 1039 52.9 2196 70.9 1127 51.1 1088 50.6 l Gobiosoma spp. 86 5.8 82 6.7 102 5.2 383 I?.4 269 12.2 363 16.9 Croaker 367 24.9 210 17.3 255 13.0 174 5.6 352 16.0 333 15.5 Portunid megalops 114 7.7 104 8.6 190 9.7 45 1.5 170 7.7 83 3.8 Shrimp postlarvac 75 5.1 63 5.2 88 4.5 66 2.1 109 49 77 3.6 Spot 71 4.8 63 5.2 99- 5.0 37 1.2 50 '2.3 57 2.6 Silversides 6 0.4 11 0.9 23 1.2 22 0.7 4 0.2 18 0.8 Atlantic menhaden 19 1.3 20 1.6 13 0.7 10 0.3 8 0.4 15 0.7 liardback shrimp 14 0.9 8 0.7 17 0.9 14 0.5 7 0.3 13 0.6 81ennies 9 0.6 7 0.6 19 1.0 25 0.8 17 0.8 8 0.4 l

Other taxa 98 6.8 61 4.9 118 5.9 126 4.0 91 4.1 95 4.5 i

Total organisms 14 73 100.0 1216 100.0 1963 100.0 3098 100.0 2204 100.0 2150 100.0 l

m M M M M m gia -

m m m m m ui M M

O I Table 2.2 Total catch and percent total of the ten most abundant orge.n-isms collected in the BSEP marsh study during 1988.

Trawl Seine Taxa Catch  % Taxa Catch

' I Spot 69,006 60.1 Grass shrimp 39,712 50.3 l lg Grass shrimp 12,623 11.0 Spot 17,828 22.6 E l Atlantic 'nenhaden 10,983 9.6 Atlantic menhaden 10,054 12.7 Bay anchovy 4,216 3.7 Mummichog 5,626 7.1 Brown shrimp 4,135 3.6 White mullet 1,529 1.9 Croaker 3,058 2.6 Striped mullet 1,231 1.6 l Southern flounder Blue crab 2,736 1,870 2.4 1.6 Brown shrimp Atlantic silverside 833 466 1.1 0.6 I Pink shrimp 1,144 1.0 Bay anchovy 398 0.5 Portunidae 1,040 0.9 Pinfish 343 0.4 Other taxa 3,S87 3.5 Other taxa 912 1.2 Total 114,798 100.0 Total 78,937 100.0 Number of efforts 204 34 I

I I

I -

I I

2-17 I

1 I

Table 2.3 Annual catch-par-unit-effort (C00E) by creek system for 13 selected species in tre BSEP marth study during 1988.

I Bald liead Walden Hott's Alligator Return Species Creek _ Creek Bay! Creek % Basin %

Atlantic menhaden Bay anchovy 28 3

78 4

46 89 28 10 101 26 l

Spot 292 302 146 195 1295 Croaker <1 6 24 25 60 Southern flounder <1 7 5 47 27 Brown shrimp 5 40 10 1 45 Pink shrimp 4 7 8 <1 11 White shrimp 0 1 <1 0 <1 Blue crab 6 13 4 7 20 I

Mumich0g 5 Atlantic silversideS 28 23 303 4

l

- Striped mulleti 27 45 - - -

White mullets 57 32 - - -

I T

B Seine samples were not collected in Mott's Bay, Alligator Creek, or 5 the return basin.

5 0ata for these species were collected using the seine instead of the trawl used to collect other species.

4 I

I ,

I I

2-18 g

M M M M M M M M M M M M - -

M M Table 2.4 Time-series analysis results for BSEP river larval fish data by station group indicating trends in density from Septeinber 1976 through August 1988.

Station groups Dutchman Creek Walden Creek Lower river Upper river 11 24 18 + 25 + 37 34 + 41 _

2  ? 2 2 Taxon Trend R Trend R' Trend R Trend R Anchovy NS 0.98 NS 0.99 +*** 0.99 +*** 0.98 Croaker +* 0.97 +** 0.98 -* 0.99 NS 0.97 Gobiosoma spp. -* 0.98 +*** 0.98 4*** 0.99 +*** 0.97 i Atlantic menhaden NS 0.93 +** 0.96 -* 0.95 NS 0.94 i

Mullet NS 0.95 +*** 0.95 -* 0.90 NS 0.87 7 Seatrout NS 0.97 NS 0.96 NS 0 94 NS 0.97 5 Spot -*** 0.99 *** 0.99 -*** 0.99 NS 0.98 Penaeus sop,. +*** 0.98 +*** 0.98 +*** 0.96 +*** 0.96 Portunid megalops NS 0.98 NS 0.97 4* 0.98 NS 0.97 Flounder *** 0.98 0.97 0.97

-* -** -** 0.97 Total organisms i *** 0.98 0.96 0.98 NS NS NS 0.96 NS P > 0.05 0.01 < P < 0.05

~

• • 0.001 < P < 0.01

• • • P < 0.001 _

+ Increasing trend Decreasing trend

~2 R Amoant of variation explained by the time-series model I Data analyzed for period from September 1978 through August 1988.

I

t Table 2.5 Time-series analysis results for 8SEP marsh data by creek indicating trends in abundance from 1981 through 1988.

Alligator Creek Mott's 8ay Walden Creek 8aldhead Creek Species 2 2 2 2 Trend R Trend R Trend R Trend R Atl4ntic menhaden NS 0.79 NS 0.75 ID NS 0.80 Spot ++** 0.84 HS 0.89 NS 0.94 ID Croaker +*** 0.80 NS 0.81 NS 0.83 +* 0.76 Striped mullet NA NA 0.80 +***

NS 0.71 Wh1te mullet NA NA NS 0.88

• 0.87 Flounder +* 0.89 NS 0.80 +*** 0.88 NS 0.80 Brown shrimp ID HS 0.83 +** 0.96 ID Pink shrimp ID NS 0.88 NS 0.90 NS 0.85 White shrimp . ID ID NS 0.90 ID Blue crab *** 0.78 *** 0.80 *** 0.80 HS 0.80 NS P > 0.05 0.01 < P < 0.05 0 A01 < P < 0.01

• • • P 2 0.001

+ Iacreasing trend Decreasing trend I

ID Insufficient data for analysis or. poor model fit NA Analysis is not applicabit because seine hauls were not made 2

R Amount of variation explained by the time-series model gg m .

m m m M M M M M M M M M M M

River 40-3 .,

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- Boldhead Creek o o-o Wolden Creek

+-~ Alligctor Greek Figure 2.1 Bottom salinity for selected stations in the Cape Fear Estuary from September 1987 through December 1988.

2-21  !

I I

Sclinity (ppt) o c o c o c o n N N - -

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s 25-3 20-k 15' O u

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- Scidhead Creek ooo Walden Creek

+-+-+ Alligator Creek I Figure 2.3 Bottom temperature for selected stations in the Cape Fear Estuary from September 1987 through December 1988.

2-23

I 11 DUTCHMAN CREEK 10' 9 i

~ ,

. .. .... ' .... ..,4,,,, ,,,,, ,,, ,,, ,, ,,, ,

s E 6

) 1 i , k.. 4 .

- \b i e y5 i 5

3 3 l O'.

82 86 87 88 78 79 SO 81 53 84 SS 89 YeCr Observed Predictec . - Year level 10' WALDEN CREEK 9'

'~L .-

1 5-4 o

e 2 3 2 I 1

O.

78 79 SO 81 82 83 84 85 86 87 88 89 Yeo'r

, - Obs erved Predicted. - Year tevel Figure 2.4 Time series analysis of totallarval organism densities collected in Dutchman and WaldenCreeks from 1979 through 1988.

I, 2-24 I

)

LOWER RIVER AREA 6'

I 5- k I O

+4

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2-25

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I 2-26 l

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I 2-28

-)

I 3.0 PLANT-RELATED MONITORING PROGRAMS 3.1 Introduction Most large organisms in the estuarf near the BSEP are not affected by I plant operations since they are excluded from the intas canal by the 9.4-m mesh screening on the diversion structure (Figure 3.1). Organisms from the estuary small enough to enter the intake canal may be affected by plant operations in one of two ways: (a) they may be impinged on the plant intake screens where they are returned to the CFE via a flume and return basin or (b) they may be entrained by the plant.

I Entrainment sampling documented the species composition, seasonal-ities, and abundances of larval and postlarval organisms passing through I the enoling system over the past 11 years. Entrainment data were analyzed through December 198d rather than August as in previous years. This change was made so that a more complete comparison could be made to larval impingement data. Juvenile / Adult (J/A) impingement sampling documented species composition, weights, and length-frequency distributions of juve-nile and adult organisms irrpinged over the past 12 years and also provided evidence of the effectiveness of the diversion structure. Larval irpinge-ment sampling, which began in 1984, provided estimates of the total number of larvae and postlarvae impinged and has evaluated the success of the I fine-mesh screens and flow minimization in reducing entrainment nf organ-isms. Survival study results from previous years were used to determine how effective the return system was at returning impinged organisms to the CFE alive (1985a, 1986, 1987, 1988).

3.2 Methods I The collection gear and sampling methods for entrainment and impinge-I ment have remained unchanged since 1984 (CP&L 1985a). The J/A impingement program included fish and shrimp 3 41 mm, portunid crabs > 25 mm, and eels e.nd pipefish 3101 mm. Individuals smaller than these cutoffs were in-cluded in the larval impingement program.

I 3-1  !

I

r l

The densities of 1crv!1 organisms entrained were calculated as in the river larval fish study (Section 2.2.2). The densities calculated for all organistre fror, samples collected per sampling date were averaged to obtaia a maan number per 1000 m of water purrped through the plant. To obtain monthly estimates of impingement, the total number of hours in a month was div!ded by the nurnber of hours sarapled dur'ng that month. The resultant expans'en f actor was then mJItiplied by thJ number (for larval impinge-ment) or by the nu-ter and weight (for J/A igig;ement) of all the organ-isms icilected during that month. The 12 monthly ,otals were then summed to obtain its annual estimate. Lensities for J/A organisms impinged w e calculated using number per million cubir. meters of water pumped through the plant thereby allowing year-to year comparisons.

3.3 Results and Discussion -

3.3.1 D<.-4nant Species Spot was the dominant organism ent-ained in 1989 and comprised 21A%

1' the mean density of all crganisms entrained (Table 3.1). Cobiosoma spp.

(16.7%) was second most abundant and croaker (14.2%) was third. Other entrained taxa (In riecreasing o-der cf abundance) were 6..chovy (? 13 rmn),

Anchoa spps (< 13 m), silversides, portunid megalopn, poatlarval shrimp, At11ntic renhadea, and pinfish, g Ten taxa accounted for 94.37 of tha total lerval organisms impuged in 1988 (Table 3.2). The dominant taxa in larval impingement were spot, -

creder, Anchoa spp., postlarvel shrimp, and portunid megalopt.. Each corrprised between 28.6% and 9.4% of the tott.1 larval impingement catch.

The same seven species h.tve (1cainated the lar.ai impingement each year sirce 1984.

The total mean dent,ity nf organisms entrained and the total number of larval organisms impinged both shoed a decrease of about /7% from 1987 (Tables 3.1, 3.2; CP&t. 1988) . Tte relative abundance. of spot in both entrainment and larval inpingement increased frm 1987, whila abundance of postlarval shrimp, portunid megalops, and Cobiosoma spp. decreased L

I 3-2 g!

l (Tables 3.1, 3.2; CP&L 1988). These trends were cbserve:1 year-level ters for the 1987 and 1989 river larval fith time-series in the i analysis results for the lower river stations (figure 2.5).

Bay anchovy dominated '/A impingement during 1988 cecounting for I 70.2% of the 3,275,471 crganisms impinged (Table 3.3). Bay anchovy war.

followed in abundaMe by croaker, blue crab, brown shrimp, spot, and Atlantic menhaden. These six species accounted for almost 87.0% of tha total catch. Total weight of all organisms collected was 17,658 kg. The density by number of J/A organisms impinged in 1988 was 13.9% 1cwer than in 1987, while the dentity by weight was 50.0% greater then in 1987.

However, a decrease of 77.7% by number and 79.1% by weight wcs obse,'ved ccmpared to the mean for the prediversion ya.ars (1977 through 1982) indi-cating a reduction in impingement of larger organisms as a "esult of the I diversion ftructure.

The si:e of bay anchovy collected during 1988 in the J/A impingement study has remained essentially unchanged since 1984 (CP&L 1985a).

l Atlantic menhadin, spot, and croaker length frequencies were similar to

. past years with the e.xception of April through June catches (CP&L 1985a). Approximately 33% of the annual catch was impinged during April (Table 3.4). An increase in modal length durina April was probably due to a large number of diversion screen failures caused by large amounts of I- drifting vegetatioa and debris in the estuary. Some larger organisms

cntered the intake canal before the screens could be repaired. 'M s re-suited in the 50% increase in weight density, although overall number density was actually reduced by 13.8% (Table 3.3). A subsequent decrease

'9 imptapement densities and/or modal lengths indicated the number of crganisms entering the intaxe canal was reduced by the diversion structure af ter the diversion screens were repaired (Table 3.4).

, 3.3.2 Seasonality and Abundance ,

The seasonality for selected entrained species was similar to pre-vious years and usually correspended to the seasonalities of larval fish in the estuary. Mcwever, sin e fine-mesh screen installation and flow-minimization implementation (Jui; 1983), peak abundance periods of 3-3

entrained species may not have corresponded to peaks observed in the river larval fish program. Peaks in entrainment can be induced by operation of streens without fine mesh or an incre:se in the flow of cooling water as detemined by plant operational needs.

Entrainment densities of pink and white shrimp peaked in early Sep-tember (Table 3.5). Densities of portunid megalops peaked in mid to late October. Croaker densities peaked in early February. A peak density was observed for Atlantic menhaden and spot in late March. Brown shrimp peaked in mid-April. Goblosoma spp. and anchovy peaked in late July and early August, respectively. These peaks in densities corresponded to l

peaks in abundance of larval fish and shellfish in the CFE.

The typical winter and summer periods of abundance observed in the entrainment and river larval fish programs were also observed in larval impingement (Table 3.6). Atlantic menhaden, spot, croaker, and brown shrimp, all ocean-spawned species, were most abundant during the winter and spring months. The period of abundance for portunid megalops occurred during the late summer and fall. Ocean-spawned species, such as pink and white shrimp, and the estuarine-spawned species, such as anchovy and Cob!osoma spp. were most abundant during the summer.

3.3.3 Entrainment Rates W 5

Entrainment rates were computed by multiplying the mean density per day of each taxon by the mean flow through the plant per day. The mean daily flow of cooling water through the BSEP ranged from 1.7 x 100m3 in late January to 5.6 x 10 6m 3from July through September.

The daily rate of total organisms entrained ranged from 1.0 x 10 3 in ,

late December to 1.1 x 107 in early August (Table 3.7). An:hovy was entrained at the highest rate which peaked in early August at 8.4 x 106 ,

The next highest rate of 4.1 x 106 occurred for spot in late March. The maximum entrainment for croaker was in early February. Atlantic menhaden g

peaked in late March and brown shrimp in mid-April. Pink and white shrimp B reached their maximum entrainment in early to mid-September, while port-unid megalops peaked in mid to late October. Gobfosoma spp. were entrained in largest .w bers in late July (Table 3.7).

34 I

I 3.3.4 Flow Rates The volume of water entrained by the plant affects the number and weight of organisms impinged and entrained. The mean monthly flow tor 1988 was 1.2 x 108m3 / month and was greater than 1987 and the 1977 through 1982 mean (Figure 3.2). Mean monthly intake flow rates in 1988 ranged from 0.1 x 107m3/ month in February to 1.7 x 108 m3 / month in August. The increased flow in 1988 was the result of two generating units which oper-ated most of the year and increased flows allowed by the NPDES permit.

I 3.3.5 Fine-Mesh Screens

• I The NPDES permit issued in 1987 allowed for a maximum allowable flow I of 922 cfs (26.1 cms) during throttled three-pump operation from December through March and 1105 cfs M1.3 cms) during unthrottled three-pump opera-tion from April through November. One stipulation was all traveling screens operating on each unit during these flow regimes be equipped with fine mesh. However, during the periods of peak summer water temperatures (July, August, and September), a fourth pump (without fine-mesh screens) may be used to obtain a maximum flow of 1230 cfs (34.8 cms) for one unit.

I Removal of some fine-mesh screens occurred from July 15, 1988, to I September 19, 1988, because large numbers of skeleton shrimp clogged the screens resulting in high differential pressures. This caused the circu-lating water pumps behind the screens to trip off. Because of the high density of skeleton shrimp on the screens, the pumps could not be re-started until the fine mesh was renoved from Unit 2 screens. Screens 29, l 2C, and 2A were placed back into service with fine mesh on August 1, 9, and 12, respectively. Fine-mesh screening was removed from 10 screen on g July 16, 1988, and replaced on Septembtr 19, 1988. Fine-mesh Screen IB was removed from service for repair on August 2,1988, and placed back

! into service on September 1, 1988.

The total mean density of larvae entra;ned from September 1978 through August 1983 was 1692/1000 m3 (Table 3.8). From September 1983 through December 1988, the total mean density was 858/1000 m 3 or 49% less 3-5

,I l

1 1

i than the density for the period when fine-mesh screens were not being used. A comparison of September 1983 through August 1986 (two fine-mesh screens per unit) with Septtmber 1986 through December 1988 (three fine-mesh screens per unit) shewed a 31% reduction in mean density as a result l

of the third fine-mesh screen. The total mean density during Sep-tember 1986 through December 1988 was 61% less than during September 1978 l through AugJst 1983 (no fine-mesh screens).

3.3.6 Survival Estimates Survival was determined for selected size classes of the dominant or '

ganisms that have been impinged at the BSEP (CP&L 1985a, 1986, 1987, 1988). Slow-screen rotation speed (75 cm/ min) is the nortual mode of cper-ation; however, screens were periodically operated on fast-screen rotation speed (200 cm/ min) depending on the amount of detritus or number of organ-isms in the water column. Screens automatically switch to f ast-screen rotation speed when instrumentation detects high differential pressure.

Survival estimates of larval fish and shellfish were therefore calculated using both screen speeds. Survival estimates of J/A fish and shellfish were calculated using slow-screen rotation speeds since differences be-tween the two speeds were slight (CP&L 1988).

l 1he 15 taxa of larvae tested for survival accounted for "3% of the 9 total larvel organisms impinged in 1988. Of these, 1.6 x 100 (42%) would have been returned to the estuary alive if the screen were on fast rota-tion (Table 3.9). If the screens were on slow rotation, 1.1 x 100 (29%)

would have been returned alive. Percer.tages of number returned alive were lower than in 1987 as a result of the increase in impingement of larval spot and Atlantic menhaden, both of which exhibited low survival on slow-screen rotation (9% and 0%, respectively). Atlantic menhaden also exhib-ited very limited survival on fast-screen rotation. Another contributing factor to the overa'.1 decrease in percentages returned alive was the decrease in impingement of pos .'srval thrimp, portunid megalops, pink and white shrimp, and blue crabs. All these organisms exhibited extremely good survival regardless of the speed of screen rotation.

I 3-6

l Survival of J/A blue crabs and brown shrimp, the most valuable com-mercial species impinged, was 92.1% and 90.7%, respectively (Table 3.10). Juvenile / Adult spot and croaker survival wcs 57.1% and 53.1%, respectively, while bay anchovy showed low servival of 1.1%.

Survival study results indicated that 13.4% of the total number of J/A or-I ganisms impinged in 1988 and 41.0% of the total weight of J/A organisms impinged were returned alive to the estuary. However, these tv figures are considered an unverestimate since an assumption uf 100% mortality for all other taxa was made due to the lack of survival data on slow. screen

l rotation for these taxa. When J/A survival estimates were calculated excluding bay anchovy and other taxa, the survival for the remaining commercially important organisms was 75.4% by number and 72.9% by weight. The use of the fish return system resulted in an estimated return of juveniles and adults of over 59.000 spot, 70,000 croaker, 147,000 blue I crabs, and 107.000 brown shrimp alive to the CFE during 1988.

3.4 Summary and Conclusions Secsonality cf organisms and the dominant species collected in the 1988 entrainment program were similar to previous years with spot account-  ;

ing for over 21% of all organisms collected.

{

I Impingement catches of larvae were dominated by spot, croaker, Anchoa spp., postlarval shrimp, and portunid megalops. Approximately 78% of the total larval organisms impinged were tested ior survival. Survival I studies indicated that between 29% and 42% of these larval organisms were returned to the estuary alive.

The 1988 Juvenile / Adult impingement catch consisted of 3.2 million organisms weighing just over 17,500 kg. Bay anchovy, croaker, and blue crab were the most abundant species impinged. Impingement per million I cubic meters of water pumped in 1988 decreased approximately 14% in number but increased 50% in weight when compared to the 1987 catch. Compared to the prediversion structure period (1977-1982), the values for number and I weight are 78% and. 79% lower showing the continued effectiveness of the diversion structure. Survival studies documented a further reduction in I

3-7

I losses through Juvenile / Adult impingement, k' hen hay anchovy and less abundant taxa were excluded, approximately 75% by number and 73% by weight of all commercially important organisms were returned to the estuary alive during 1988 including approximately 90% of the most valuable commercial l

species (blue crab and brown shrimp). When all data were corsidered, the fish return system allowed approximately 13% by number and 41% by weight of all juvenile / adult organisms impinged to be returned to the estuary alive.

Overall, fewer organisms were affected by the operation of the Bruns-wick Steam Electric Plant than in past years. The diversion structure ex-cluded most large organisms. Even though more cooling water was withdrawn than during the previous year, fewer larval organisms were entrained prob-l ably due to increased use of fine-mesh screens. A large percentage of the larval and Juvenile / Adult organisms impinged was returned to the Cape Fear Estuary alive.

I 5

I 3-8

l l l l

l Tsble 3.1 Mean den;ity (number /1000 3 m ) and percent total of fish, penteid shrimp, and portunid megalops entrained at the BSEP from September 1987 through December 1988.

I Trecies

~

Density Percent Spot 122 21.6

~

Gobiosoma spo. 94 16.1 l Croaker Anchovy 80 79 14.2 14.0 I Anchoa spp.

Silversides 51 37 .

9.0 6.6 Portunid megalops 22 3.9 l Shrirrp postlarvae Atlantic menhaden 21 12 3.7 2.1 I Pinfish Other taxa 10 36 1.8 6.4 I

Total _ 564 200.0 Table 3.2 Total larvae impinged at the BSEP during 1988, ranked by per-I cent.

Species Total number Percent of total Spot 1.4 x 10 8 28.6 l Croaker Anchoa spp.

8.3 x 10 7 5.3 x 10 16.9 10.8 Shrimp postlarvae S.1 x 107 10.4 Portunid megalops 4.6 x 10 7 9.4 Anchovy 3.2 x 10 7 6.5 Gobiosome spp. 3.1 x 107 6.3 Atlantic menhaden 1.6 x 10 7 3.3 I Pinfish Hardback shrimp 6.9 x 10 6 6.3 x 106 3,4 1,3 Other taxa 2.5 x 10 7 5.1 Total 4.9 x 108 100.0 I

3-9

Table 3.3 Juvenile and adult impingement at the BSEP during 1988 wtth comparisons to prev 1cu;, years.

Number per million Weight (kg) per Percent Total cubic meters of Total million cubic meters i Species of catch number water pumped weight (kg) of water ptv.d Bay ancnovy 70.2 2,299,249 1,566 2,213.1 1.5 Croaker 4.0 131,988 90 3,963.4 2.7 Blue crab 3.7 119,479 81 3,597.0 2.4 Brown shrimp 3.6 118.116 80 1,114.4 0.8 Spot 3.2 104,697 71 930.5 0.6 Atlantic menbaden 2.3 75,187 51 1,316.3 0.9 Blackcheek tonguefish 1.5 47,676 33 190.9 0.1 y Striped anchovy 1.4 47,268 32 274.8 , 0.2 5 Lesser blue crab 1.3 41,102 28 113.0 0.1 Fringed flounder 0.8 24,795 17 101.4 0.1 Additional taxa (85)I 8.0 265,914 181 3,834.1 2.5 1988 totals 100.0 3,275,471 2,230 17,658 12.0 1987 totals 3,573,214 2,569 10,985 8.0 Percent change (1938 -13.9 +50.0 vs. '.987) 1977-1982 annual rean 14,267,926 10,000 83,523 57.3 Percent change (1988 -77.7 -79.1 vs. mean of 1977-1932)

I Number in parenthesis indicates taxa number.

_ _ _o

_ _ _ _ _ . _ _ . _ . ~ _ _ _ _ _ _ _ . _ . _- __ -- .._ _ _ _ _ _ _ _ _ _ - _

'I Table 3.4 Total juvenile and adult impingement catch per million cubic

! meters of water entrained and modal length (mm) f r selected I species during April, May, and June 1988 at the BSEP .

-. .. = .

iI _

Total 1988 April May June

, Total catch 2231 8181 3571 2017 Percent of annual catch 100 32.6 16.4 9.5 jl Croaker 90 405 (130) 322(125) 94 (130)

Spot 71 114(105) 280 (165) 195 (45)

Atlantic menhaden 51 143 (105) 64(95) 258 (45) 1 I i Humbers in the parentheses are modal lengths ,' n).

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Sample Total Atinntic Portunid Penacas date organisms Croaker menhaden Spot Anchovy Gordoson.a megalops spp.

05JAH88 4,941 4.346 10 211 163 0 62 1 12JAH8G 5,357 4,190 4 733 233 0 0 0 20JAN88 8,457 6,599 23 700 723 4 0 0 26JAN88 8,606 7,201 31 870 243 0 0 0 l 02fEB88 12,293 7,758 75 2,458 717 0 0 0 09fE888 13.035 4,310 161 6,565 810 0 0 0 16FEs188 7,320 3,271 125 3,181 310 0 0 0 l

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Sample Total Atlantic Portunid Penaeus date organisms Croaker menhaden Spot 8ichovy Gobinsomu rnegalops spp.

06JUL88 43,469 0 0 0 20.918 10,969 269 10,587 12JUL86 5,056 0 0 0 1.E34 573 140 1,998 19JUL88 1,666 0 0 0 287 275 4 506 26JUL88 3,100 0 0 0 938 1,779 37 100 02AUG88 5,356 0 0 0 3,422 913 204 280 09AUG88 4,175 0 0 0 2,603 652 85 163 16AUG88 13,422 0 0 0 5,.71 1,159 103 1,374 23AUG83 6.051 20 0 0 2,76, 138 225 2,426 06SEP88 6,207 0 0 0 404 196 1,392 3.115

[13SEP88 7,485 0 0 0 1,400 199 897 2,454 20SEP88 5,103 4 0 0 655 1,172 74 2,725 l 275EP88 ' 5,350 28 0 0 278 132 3,546 774 040CT88 2,800 34 0 0 49 -36 1,922 599 l 110CT88 12,629 115 0 0 123 80 9,696 1,734 180Ci89 5,054 10 0 0 67 50 4,349 298 250CT88 3,92-? 124 0 0 33 42 3,168 195 08NOV88 7,58fi 3,645 0 0 617 8 2,667 15'i 15NOV88 1,87c 642 0 0 34 0 1,036 87 22NOV88 4,644 62 0 0 34 4 4,318 135 29NOV88 1,545 451 0 0 14 0 945 54 07DEC88 1,408 760 0 4 132 0 386 16 13DEC88 3,535 3,165 33 8 200 0 24 0 200EC88 807 179 2 24 62 4 295 0 27DEC88 1,251 226 10 113 90 0 340 0

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September 1978 - Septenner 1983 - September 1983 - September 1986 -

August 1983 Augusi 1986 December 1988 December 1988 Species Density Percent Density Percent Density fercent Density Percent Ccbiosoma spp. 373 22.0 289 30.5 249 29.0 160 24.5 Spot 164 9.7 69 7.3 80 9.3 105 16.0 Croaker 170 10.0 71 7.5 76 8.9 88 13.4 Anchoa spp. 191 11.3 141 14.9 122 14.2 80 12.2 m Anchovy 210 12.4 64 6.8 65 7.6 68 10.4 Portunid megalops 235 13.9 36 3.8. 35 4.1 32 4.9 Shrimp postlarvae 145 8.6 33 3.5 33 3.8 31 4.7 Silversides 61 3.6 139 14.6 105 12.2 29 4.4 Biennies 13 0.8 21 2.2 18 2.1 9 1.4 Pinfish 6 0.4 2 0.2 4 0.5 8 1.2 Other taxa 124 7.3 82 8.7 71 8.3 45 6.9 Total 1692 100.0 947 100.0 858 100.0 655 100.0 33 M M M M M M M M M M M M M M M M M M

g g g g g g 3 m a m m W W M M M M M Table 3.9 Percent during survival cnd number of impinged lerval orgcnisms returned alive to the Cape Fear Estuary 1988.

Percent survival Number returned alive Fast- Slow- Fast- Slow-Total screen screen screen screen Species number impinged rotation rotation rotation rotation "oaker 7 8.3 x 10 33.7 14.4 2.8 x 10 77 1.2 x 10 7 Spot 1.4 x 20 0 29.4 9.0 4.1 x 10 1.3 x 10 7 Anchovy 3.2 x 10 77 0.7 0.3 2.2 x 10 5 9.6 x 10 4 Shrimp postlarvac 5.1 x 10 6 Flounder 90.3 80.3 4.6 x 10 7 4.1 x 10 7 1.4 x 10 93.2 -

1.5 x 10 6 1.5 x 10 6 Striped mullet 69.8 1.1 1.0 x 10 6 1.1 x 105 Portunid megalops 4.6 x 10 7 87.0 86.3 4.0 x 10 7 4.0 x 10 7 Weakfish 2.0 x 10 6 12.6 -

2.5 x 10 6 4.7 x 10 6 m Searchin 89.8 -

4.2 x 10 6 4 Hardback shrimp 6.3 x 10 6

" Pink and white shrimp 78.8 48.4 5.0 x 10 6 3.0 x 10 6 4.5 x 10 3 95.8 75.0 4.3 x 10 3 3.4 x 10 3 Blue crns 2.4 x 10 5 91.7 95.1 2.2 x 10 5 Cobione:Ius spp. 2.5 x 106 2.3 x 10 5 Crevalle jack 15.4 -

3.8 x 10 5 1.2 x 10 4 35.9 -

4.3 x 10 3 Atlantic menhaden 1.6 x 10 7 3.2 0.0 5.1 x 10 5 0 Anchoo spp. 5.3 x 10 7 - - -

Other organisms (57 taxT) 5.6 x 10 7 Total organisms 4.9 x 108 Total organisms tested 3.8 x 10 8 t 1.6 x 10 5 0 (73;)I 1.1 x 108 (29%)5 1.6 x 10 8 (42%)E1.1 Total organisms tested 3.5 x 10 (71%)

(excluding anchovy) 0 (461) x 106 (31%)E I Percent of total organisms impinged that were tested.

S Percent of total organisms impinged that were tested excluding anchosy.

5 Percent of total organisms tested that were returned alive.

E Percent of total organisms tested (excluding anchovy) that were returned alive.

EI Table 3.10 Percent survival and number of juvenile and adult orgtisisms returned alive to the Cape fear Estuary duri g slow-screen rotation in 1988.

I Impinged Percenti Estimated survival l

}pecies Rumber Weight (kg) survival Number Wefqht (kg) l Blue crabs 160,581 3,710 02.1 147,895 3,417 1

Brown shrimp 118.116 1,114 90.7 107,131 1,010 Shrimp spp.

(pinkandwhite) 34,944 180 86.5 30,2?7 156 l Spot 104,697 931 57.1 59,782 532 g

Croaker 131,988 3.963 53.1 70,086 2,104 Bay anchovy 2,299,249 2,213 1.1 25,292 24 Other taxa 425,896 5547 N.D. N.D. N.D.

I Total 3,275,471 17,658 440,413 7,243 g

Percent survival 13.4 41.0 Total 976,222 15,445 415.121 7,219 (e.stludin bay anchovy Percent survival 550,326 9,899 42.5 46.7 l

Total 415,121 7,219 (excluding bay at.chovy and othertaxa)

Percent survival 75.4 72.9 iCP&L 1988 N.D. No survival data were collected for other taxa en slow-screen rotation.

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0, , , , , , , , , i , i Jon Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month I

W 1988 (mean monthy fbw - 122.4) E 8-G O 1987 (mean monthy fbw 115.0) E e-+ + 19771982 (mean monthh flow .120.4)

Figure 3.2 Mean monthly now of water pumped at the BSEP from 1977 through 1982,1987, and 1988.

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4.0 REFERENCES

I Blaber, S. J., and T. G. Blaber.

tion of juvenile estuarine 17:143-162.

1980. Factors af/ecting the distribu-and inshore fish. J. Fish. Biol.

Boehlert, G. W., and B. C. Mundy. 1988. Roles of behavioral and physical factors in larval and juvenile fish recruitment to estuarine nursery areas. American Fisheries Symposium. 3:51-67 CP&L. 1980. 1979 monitoring program. BSEP Cape Fear Studies, Supple-ment I. Carolina Power & Light Company, New Hill, NC.

1982. Brunswick Steam Electric Plant annual biological moni-tering report, 1981. Carolina Power & Light Company, New Hill, NC.

l 1983. Brunswick Steam Electric Plant annual biological moni-toring report, 1982. Carolina Power & Light Company, New Hill, NC.

I ,,

1984.

toring report.

Brunswick Steam Electric Plant 1983 biological moni-Carolina Power & Light Company, New Hill, NC.

I 1985a.

toring report.

Brunswick Steam Electric Plant 1984 biological mcai-Carolina Power & Light Company, New Hill, NC.

1985b. Brunswick Steam Electric Plant, Cape Fear Studies, I Interpretive Report. Carolina Power & Light Company, New Hill, NC.

1986. Brunswick Steam Electric Plant 1985 biological moni-toring report. Carolina Power & Light Company, New Hill, NC.

1987. Brunswick Steam Electric Plant 1986 biological moni-toring report. Carolina Power & Light Company, New Hill, NC.

1988. Brunswick Steam Electric Plant 1987 biological moni-toring report. Carolina Power & Light Company, New Hill, NC.

Copeland, B. J., R. G. Hodson, and R. J. Monroe. 1979. Larvae and post-larvae in the Cape Fear River estuary, North Carolina, during opera-I tion of the Brunswick Electric Plant, 1974-1978. North Carolina State University, Raleigh, NC.

I Deegan, L. A., and J. W. Day, Jr. 1984 Estuarine fishery habitat re-quirements. Pages 315-336 fn B. J. Copeland, K. Hart, N. Davis, and S. Fridey (eds.). Research for Managing the Nation's Estuaries:

Preceedings of a Conference. Raleigh, NC.

I ,

Giese, G. L., H. B. Wilder, and G. G. Parker, Jr. 1979. Hydrology of major estuaries and sounds of North Carolina. U.S. Geological Survey Water Resources Investigations 79-46. Raleigh, NC.

_ _ _ 1985. Hydrology of major estuaries and sounds of North Caro-lina. U.S. Geological Survey Water Supply Paper 2221. Raleigh, NC.

4-1 4

I Gunter, G. 1961. Some relatiens of faunal distributions to salinity in estuarine waters. Ecol. 37:616-619.

Hodson, R. G. 1979. Utilization of marsh habitats as primary nursery areas by young fish and shrimp, Cape Fear Estuary, North Carolina.

BSEP Cape Fear studies, Volume Vill. North Carolina State University, E Raleigh, NC. 5 Hodson, R. G., C. R. Bennett, and R. J. Monroe, 1981. Ichthyoplankton samplers for simultaneous replicate samples at surf ace and bottom.

Estuaries 4:176-184 Huish, M. T., and J. P. Geaghan. 1979. A study of adult and juvenile fishes of the lower Cape Fear River near the Brunswick Steam Elttctric Plant, 1975-1976. North Carolina State University, Raleigh, NC.

Jones, P. W. , F. D. Martin, and J. D. Hardy, Jr. 1978. Development of

'ishes of the Mid-Atlantic Bight, Volume 1. U.S. Fish and Wildlife Service. Washington, DC.

Joseph, E. B. 1973. Analysis of a nursery ground. Pages 118-121 in I A. L. Padieco (ed. ) . Proceedings of a workshop on egg, larval, and juvenile stages of fish in Atlantic Coast estuaries. Highlands NC.

Kneib, R. T. 1984 Patterns in the utilization of the 19tertidal salt marsh by larvae s...' juveniles of Fundulus heteroclitus (Linnaeus) and a Fundulus luefoe (Baird). J. Exp. Mar. Biol. Ecol. 83:41-51. 3 Lasker, R. 1975. Field criteria for survival of anchovy larvae: The relation betwee' inshore chlorophyll maximum layers and successful first feeding. Fish. Bull. 73:453-462.

Lawler, J. P., M. P. Weinstein, H. Y. Chen, and T. L. Englert. 1988. E Modeling of physical and behavioral mechanisms influencing recruitment E of spot and Atlantic croaker to the Cape Fear Estuary. American Fisheries Symposium. 3:51-67.

Leming, T. D., and D. R. Johnson. 1985. Application of circulation mod-els to larval dispersement and recruitment. Mar. Tecn. Soc. J.

19:34-41.

McHugh, J. L. 1967. Estuarine nekton. Pages 581-620 in G. H. Lauff l

(ed.). Estuaries. American Association for the Advancement of Sci- E ence. Washington, DC. E Miller, J. M., S. W. Ross, and S. P. Epperly. 1984. Habitat choices in estuarine fishes: Do they have any7 Pages 337-352 in B. J. Copeland, K. Hart, N. Davis, and S. Friday (eds.). Research for Managing the Nation's Estuaries': Proceedings of a Conference. Raleigh, NC.

Miller, J. M. 1985. Effects of freshwater discharges into primary nursery areas for juvenile fish and shellfish: criteria for their protection. Pages 62-84 in _ Water Management and Estuarine 3 Nurseries. UNC Sea Grant publication UNC-SG-WP-85.2. Raleigh, NC. E 4-2 I

I I Norcress, L. B., and R. F. Shaw. 1984. Oceanic and estuarine transport of fish eggs and larvae: A reviee.. Trans. Am. Fish. Soc.

l 113:153-165.

Pietrafesa, L. J., G. S. Janowitz, J. M. Miller, E. B. Nobic, S. W. Ross, I and S. P. Epperly. 1986. Abiotic factors influencing the spatial and temporal variability of juvenile fish in Pamlico Sound, North Caro-lina. Pages 341-353 in V. S. Kennedy (ed.). Estuarine Variability.

Academic Press, Inc., New York, NY.

Rogers, S. E. , T. E. Targett, and S. B. Van Sant. 1984 Fish-nursery use in Georgia salt-marsh estuaries: The influence of springtime fresh-water conditions. Trans. Am. Fish. Soc. 113:595-606.

Weinstein, M. P. 1979. Shallow marsh habitats as primary nurseries for I fishes and shellfish, Cape Fear River, North Carolina. Fish. Bull.

77:339-357.

Weinstein, M. P., S. L. Weiss, and M. F. Walters. 1980. Multiple deter-I min (nts of community structure in shallow marsh habitats, Cape Fear Estuary, NC. Mar. Biol. 58:227-243.

I Weinstein, M. P. , and M. F. Walters. 1981. Growth, survival, and produc-tion in young-of-year populations of Lefostomus xanthurus Lacepede residing in tidal creeks. Estuaries 4:185-197.

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I APPENDIX Special Trawl Study I

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I INTRODUCTION l Tresh oligohaline marshes are important nursery areas for many com-mercia11y important fish species (Rozas and Hackney 1984). Annual vari-ations in abundance of organisms in these marshes can be large; therefore, an understanding of the f actors which cause these large variations is I needed to determine if operation of the BSEP is having an adverse effect on the use of these marshes by juvenile estuarine dependent fish.

METHODS '

Sample Collection Samples were collected once every two weeks from January through the first week in May 1988. This study period was chosen in order to coincide with historical periods of maximum recruitment of spot to the CFE and associated tidal creeks (CP&L 1988). One sampling station each was lo-cated in Walden Town, and Alligator Creeks (Figure A-1).

The 3.2-m trawl and tow distance used for this study were identical to that used for the marsh program (CP&L 1982). Each station was sampled with the trawl on a low-outgoing or low-slack tide. Bottom temperature

('C) and salinity (ppt) were rec rded for each trawl sample as well as during the previous or following hign-slack tide.

All organisms were identifitd and counted. Minimum and maximum lengths were recorded for grass shrimp, blue crab, and portunid crabs. Up I to 50 individuals of each of the remaining species were measured to the nearest millimeter.

Data Analysis I -

A regression analysis (Ott 1984) was performed on the number of spot I collected by trip in Alligator Creek with the loge (catch +1) regressed against selected environmental variables. Variables of particular inter-est were total freshwater inflow, salinity, and salinity fluctuation. A I

A-2

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I log, (X+1) transformation was performed on the freshwater inflow data.

Freshwater inflow was further divided into two components: The first was the seven-day average freshwater inflow during the sampling week and the second was the seven-day average freshwater inflow one week prior to the l

sampling week. Freshwater inflow was calculated according to Giese et al.

(1979, 1985) to estimate the total freshwater inflow to the Cape Fear Estuary (CFE) taking into account the lag time between the gaging stations and the CFE.

RESULTS AND DISCUSSION The catch for spot was highest in Walden Creek followed by Alligator and Tcwn Creeks (Table A-1). The low catch in Tewn Creek was probably due to the station location which was subject to relatively high-flow velocity most of the time. Attempts to place a station further up the tidal creek were not possible cue to numerous hangs. This station was therefore not representative of this creek system, and for this reason, data from Town

. Creek were not analyaed.

Results of the regression analysis showed that a negative linear I

relationship using freshwater inflow one week prior to sampling best ac-counted for most of the variation in the abundance of spot at Alligator Creek (Teble A-2). Models using freshwater inflow, salinity, and salinity B fluctuaticn during the sampling week did not perform as well. B The number of spot coilected in Alligator Creek on March 8 and April 7 was greater .than that collected in Walden Creek. The seven-day average freshwatar inflow one :eek prior to each sampling date decreased to below 140 cms indicating a negative correlation between freshwater in-flow ar.d catch (Figure L 2). Salinity for these dates in Alligatcr Creek was O ppt on all tides except for March 8 (Table A-3). These results support the conclusions of Rcgers et al. (1984) that initial use of the upt.er estuary nursery areas by some species is based on the timing and mhynitude of changing freshwater inflow rather than salinity. Spot pechebly moved into A1113ater Creek as a result of water-current transport even thougn freshwater conditions existed at this station. Decreases in I

A-3 E_

R Decreases in freshwater inflow will have an effect on estuarine circulation patterns within a day or less; however, salinity adjustments at the head of the estuary may take several days depending on the magnitude of freshwater inflow (Lepage and Ingram 1988). Salinity conditions recorded in Alligator Creek on the sampling dates are therefore a good indication of salinity conditions existing during the entire period ft.' January through the first week in May.

I Increases in freshwater inflow limit the penetration cf the net-nontidal drift upriver (Giese et al. 1979,1985). The upriver movement of organisms such as spot, which use the net-nontidal drif t to move up the estuarine axis (Weinstein tt al.1980), would therefore be limited by in-creases in freshwater inflow. Since spot migrate into the upper portion of the water column at night and on a rising tide (Weinstein et. al 1980),

this species is more severely affected by increasing freshwater inflow than other species.

I Species such as croaker and finunder, which are con-sistently more abundant in the upper CFE (CP&L 1988), exhibit different behaviors. Croeker do not migrate vertically to the same degree as spot and floundet and are appawitly able to lic on the bottom and avoid down-river ansport during periods of high freshwater inflow (Weinstein et. al 1980; Boehltrt and Mundy 1988; Luler et al.1988).

Changing freshwater inflow during the recruitment of larval spot to the CFE influenced the eventual utilization of the upriver nursery areas by juveniles of this species. Initial recruitment of spot to the upriver I nurseries was probably a result of water-current transport rather than salinity. This cor.clusion is supported by that of Lawler et al. (1988) who found that once inside the iniet, tidt.' flows, net-nontidal flows, and the vertical migratory behavio cf spot are major determinants of recruit-ment and distribution in the CFE. Large variations in the annual abundance of spot are evident in the fresh oligohaline marshes of the uppec CFE. However, fluctustions in the, yearly abundance of spot in the upriver nursery areas relative to the lower nursery areas of the CFE are I of the BSEP.likely the result of variation in freshwater inflow and not the operation t

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Table A-1 Total catch and perce.it total catch of the five most abundant species collected at each creek and all creeks combined from January to May 1988.

A11 Walden Town Al1Igator Stations Creek Creek Creek Species Catch  % Catch  % Catc} C i - Catch  %

Spot 19,703 81.3 13,112 83.2 6,541 50 11.8 81.2 Atlantic menhaden 1,547 6.4 1.392 8.8 1 0.2 154 1.9 Grass shrimp 1,273 5.2 860 5.5 252 59.3 161 2.0 Southern flounder 1.035 4.3 146 0.9 2 0.5 887 11.0 Croaker 333 1.4 44 0.3 90 21.2 205 2.5 Portunidae 72 0.3 57 0.4 3 0.7 12 0.2 o HakcJ goby 15 < 0.1 5 < 0.1 9 2.1 1 < 0.1 An.srican eel .5 < 0.1 0 0 4 0.9 0 0 Other Mxa 249 1.0 136 0.9 14 3.3 99 1.2 Total 24,237 100.0 15,752 100.0 425 100.0 8,060 100.0 Number of efforts = 27 l

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.I Table A-2 Regression analysis for spot collected in Alligator Creek as a function of selected environmental variables from January to Coefficient of determination Variable R 2

I Freshwater inflow one week prior to sampling (seven-day average) 0.80 Freshwater inflow during the sample week 0.47

- (seven-day average)

. Low-tide salinity in Alligator Creek 0.13 i

High-tide salinity in Alligator Creek 0.13 Salinity fluctuation in Alligator Creek 0.13 Table A-3 High-tide (H) and low-tide (L) salinity (ppt) values recorded for Walden and Alligator Creeks from January to May 1988 I -

Walden Creek Alligator Creek DATE H L Fluctuation H L fluctuation

, 1/14/88 5 4 1 0 0 0 1/28/88 8 5 3 0 0 0 2/11/88 / 4 3 0 0 0

} 2/25/88 8 6 2 0 0 0 3/08/88 12 9 3 1 0 1 3/24/88 10 6 4 0 0 0 4/07/88 14 12 2 0 0 0 4/22/88 14 11 3 0 0 0 l 5/03/88 14 11 3 2 0 2 I

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A- 7 l

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O Jan 14 Jan 28 Feo11 Feb 25 Mw8 Mw 24 Apr7 Apr 22 May 03 e st.

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Figure A 2 Trawl catches of spot in Walden and Alligator Creeks compared to seven-day average freshwater inflow one week prior to sampling date, January through May 1988.

I A- 9

I REFERENCES Boehlert, G. W., and B. C. Mundy. 1988. Roles of behavioral and physical factors in larval and juvenile fish recruitment. to estuarine nursery areas. American Fisheries Symposium. 3:51-67.

I 1982. Brunswick Steam Electric Plant Annual Biological Mon-itoring Report, 1981. Carolina Power & Light Company, New Hill, NC.

CP&L. 1988. Brunswick Stears. Electric ' Plant 1987 biological monitoring I report. Carolina Power & Light Company, New Hill, NC.

I Giese, G. L., H. B. Wilder, and G. G. Parker, Jr. 1979.

major estuaries and sounds of North Carolina. U.S. Geological Survey Water Resources Investigations 79-46. Raleigh. NC.

Hydrology of 1985. Hydrology of major estuaries and sounds of North Caro-lina, U.S. Geological Survey Water Supply Paper 2221.

Lawler, J. P., M. P. Weinstein, H. Y. Chen, and T. L, Englert. 1988.

l Modeling of physical behavioral and mechanisms influencing recruitment of spot and Atlantic croaker to the Cape Fear Estuary.

American Fisheries Symposium. 3:51-6/

Lepage, S. , and R. 3. Ingram. 1988. Estusrine response to a freshwater pulse. Est. Coast. Shelf Sci. 25:657-667.

Ott, L. 1984. An introduction to statical methods and data analysis.

PWS Publishers. Boston, MA.

Rogers, S. E., T. E. Targett, and S. B. Van Sant. 1984 Fish-nursery use in Georgia salt-marsh estuaries: The influence of springtime freshwater conditions. Trans. Am. Fish. Soc. 113:595-606.

Rozas, L. P., and C. T. Hackney. 1984. Use of oligohaline marshes by g fishes and macrofaunal crustaceans in North Carolina. Estuaries.

E 7:213-224 Weinstein, M. P., S. L. Weiss, R. G. Hodson, and L.R. Gerry. 1980.

1 t

I Retention of three taxa of postlarval fishes in an intensbely flushed tidal estuary, Cape Fear River, North Carolina.

78:419-435.

Fish. Bull, l-I

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