ML20138F471
| ML20138F471 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 07/31/1996 |
| From: | NORMANDEAU ASSOCIATES, INC. |
| To: | |
| Shared Package | |
| ML20138F373 | List: |
| References | |
| NUDOCS 9705050404 | |
| Download: ML20138F471 (57) | |
Text
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SEABROOK STATION 1995 ENVIRONMENTAL STUDIES REPORT SURFACE PANELS SECTION Prepared for NORTH ATLANTIC ENERGY SERVICE CORPORATION
. P.O. Box 300 Seabrook Station Seabrook,New Hampshire 03874 Prepared by )
NORMANDEAU ASSOCIATES 25 Nashua Road Bedford, New Hampshire 03310 i
Critical reviews of this report were provided by: i l
The Seabrook Station Ece!cgical Advisory Committee:
Dr. John Tietjen, Chairman (City University of New York)
Dr. W. Huntting Howell (University of New Hampshire)
Dr. Bernard J. McAlice (University of Maine)
Dr. Saul B. Saila (emeritus, University of Rhode Island)
Dr. Robert T. Wilce (emeritus, University of Massachusetts) s Northeast Utilities Service Company Aquatic Services Branch Millstone Nuclear Power Station Waterford, Connecticut 06385 July 1996 l
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i 9705050404 970429 DR ADOCK0500g3
TABLE OF CONTENTS PAGE 7.0 S URFAC E PAN ELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 S UM M ARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-ii LIST OF FIGURES ................................. . . . . . . . . . . . . . . . 7-iii LIST OF TAB LES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 7-iv 1
7.1 INTROD UCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7- 1 7.2 METHODS .................................................. 7-1 7.2.1 Field Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7- 1 i 7.2.2 Laboratory Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2 7.2.3 Analytical Methods . . . . . . . . . . . . .'. . . . . . . . . . . . . . . . . . . . . . . . . . 7-3 i 7.3 RES U LTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 7.3.1 Short-Term Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 7.3.2 Monthly Sequential Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7 7.3.3 Quarterly Sequential Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9 7.3.4 One Year Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10 l 7.4 DISC U SSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7- 1 1
7.5 REFERENCES
CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15 1
7-i j
SUMMARY
The fouling community settling and developing on surface panels has shown predictable seasonal patterns l
throughout the study. Trends observed during the operational and preoperational periods were similar. Most measures of enmnumity saucture (biomass, abundance, number of taxa), and abad=ca and frequencies of indivxiual l
taxa indicate fouling camnumity settlement (on panels exposed for one month) and development (on panels expose for periods of 1 12 months) showed no significant differences between preoperational and operational periods.
Some parameters measured on the year-end fouling community (panels exposed for one year) indicated changes ;
q during the operational period that were not consistent between nearfield and farfield areas. The wood-boring mollusk, Teredo sp. occurred in wood blocks for the first time since 1980, at both nearfield and farfield stations.
This orgamam has been present in the bivalve larvae study each year since 1984, and adults have been observed i on panels during the preoperational period in 1976,1979 and 1980. None cide findings in 1995 or in previous operational years indicate that Seabrook Station operation has any effect on the local fouling community.
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SUMMARY
The fouling community sealing and developing on surface panels has shown predictable seasonal panerns
- s. throughout the study. Trends observed during the operational and preoperational periods were similar. Most measures of communny structure (biomass, *ndmace, number of taxa), and abundances and fmquencies of individual j
taxa indicate fouling community seulement (on panels exposed for one month) and development (on panels exposed l for periods of 1-12 months) showed no significant differences between preoperational and operational periods.
I Some parameters measured on the year-end fouling community (panels exposed for one year) indicated changes during the operational period that were not consistent between nearfield and farfield areas. The wood-boring
- . mol!usk, Teredo sp. occurred in wood blocks for the first time since 1980, at both nearfield and farfield stations.
{ '} This organism has been present in the bivalve larvae study each year since 1984, and adults have been observed on panels during the preoperational period in 1976,1979 and 1980. None of the fmdings in 1995 or in previous
]l - i perational years indicate that Seabrook Station operation has any effect on the local fouling community.
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LIST OF FIGURES !
I PAGE 7-1. Surface panel sampling stations . . . . . . ...... .............. ......... . ..
7-2. Monthly number of taxa (on two replicate panels), abundance, and biomass on short-term panels at nearfield/ farfield station pair B 19 and B31 during the operational period (1991-1995) and 1995 compared to the means and 95 % confidence limits during the preoperational period (1978-1984 and July 1986-December 1989) . . . . . . . .......... ............ ....
7-3. A comparison between stations of the logdx+ 1) no. per panel total abundance and Mytilidae abundance in short-term panels during the preoperational (1978-1985; 1987-1989) and operational (1991-1995) pe riods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 1
) 7-4. Annual geometnc total abundance and abundance of Mytilidae on short-term panels at , Stations
! B 19 and B31, 1978-1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7-5. l.og abundance (no. per panel) of Mytilidae, and Jarsa marmorata, and monthly mean percent I frequency of Tubulada sp. on shon-term panels at Stations B19 and B31 during the operational period (1991-1995) and 1995 compared to the mean abundance or percent frequency and 95 % confidence limits during the preoperational period (1982-1984 and July 1986-December 1989) ............................................................
7-6. Mean biomass (g/ panel) and Mytilidae spat (percent frequency of occurrence) during the operational period (1991-1995) and in 1995 compared to mean and 95 % confidence limits during the preoperational period (Stations B19 and B31 from 1978-1984 and July-December i 1986-1989 for biomass and 1987-1989 for Mytilidae) on monthly sequential panels .........
- 7-7. Monthly mean percent frequency of occurrence for Jassa marmorata, Balanus sp., and Tubularia sp. at Stations B19 and B31 during the operational period (1991-1995) and in 1995, compared to mean and 95 % confidence limits during the preoperational period (1987-1989) on monthly sequential panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
- 7-8. Mean biomass (g/ panel) and Mytilidae spat (percent frequency of occurrence) and 95%
confidence limits (n=3) during 1995 from Stations B19 and B31 on Quarterly Sequential panels compared to the monthly preoperational means (1987-1989) . . . . . . . . . . . . . . . . . . . .
7-9. Mean percent frequency of occurrence and 95 % confidence limits (n = 3) for Jassa marmorata.
Balanus sp. and Tubularia sp. at Stations B19 and B31 during 1994 and 1995 compared to the monthly preoperational means (1987-1989) on Quarterly Sequential panels . . . . . . . . . . .
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LIST OF TABLES :
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! I 7-1. MEANS (PER PANEL) AND COEFFICIENT OF VARIATION (%) FOR SELECTED I
{ PARAMETERS AND SPECIES ABUNDANCES AT STATIONS B19 AND B31 DURING l THE PREOPERATIONAL AND OPERATIONAL PERIODS (1991-1995), AND 1995 M EAN S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .....................
7-2. RESULTS OF ANALYSIS OF VARIANCE COMPARING MONTHLY TOTAL NUMBER OF TAXA, NONCOLONIAL FAUNAL ABUNDANCE, TOTAL BIOMASS, AND SELECTED SPECIES ABUNDANCE OR PERCENT FREQUENCY ON SHORT-TERM PANEIS ATTHE MID-DEFITI STATION PAIR (B19, B31) DURING PREOPERATIONAL (1978-1989) AND OPERATIONAL (1991-1995) PERIODS . . . . . . . . . . . . . . . . . . . . . . . . .
7-3. ANOVA RESULTS COMPARING MONTHLY SEQUENTIAL PANEL BIOMASS AT THE MID-DEPTH (B19, B31) STATION PAIR DURING PREOPERATIONAL (1978-1989)
AND OPERATIONAL (1991-1995) PERIODS . . . . . . . . . . . . . . . . . ......,........
7-4. NEARFIELD/FARFIELD COMPARISON OF ANNUAL MEAN AND STANDARD ERROR .
OF MYTILIDAE SPAT AND JASSA MARMORATA LENGTHS (mm) FROM MONTHLY SEQUENTIAL PANELS COLLECTED IN 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7-5. NEARFIELD/FARFIELD COMPARISON OF ANNUAL MEAN AND STANDARD ERROR OF MYTILIDAE SPAT AND JASSA MARMORATA LENGTHS (mm) FROM QUARTERLY SEQUENTIAL PANELS COLLECTED IN 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7-6. DRY WElGHT BIOMASS, NONCOLONIAL NUMBER OF TAXA, ABUNDANCE, AND LAMINARIA SP. COUNTS ON SURFACE FOULING PANELS SUBMERGED FOR ONE YEAR AT STATIONS B19 AND B31. MEAN AND STANDARD DEVIATION FOR THE PREOPERATIONAL PERIOD (1982-1984 AND 1986-1989) AND MEAN FOR 1995 AND THE OPERATIONAL PERIOD (1991-1995) ..............................
7-7.
SUMMARY
OF EVALUA'I1ON OF DISCHARGE PLUME EFFECTS ON THE FOULING
. COMMUNITY IN VICINITY OF SEABROOK STATION . . . . . . . . . . . . . . . . . . . . . . . . .
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I. 7.0 SURFACE PANELS '
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7.1 INTRODUCTION
l The surface fouling panels program was designed to study species settlement pat- :
terns and fouling community development in the discharge plume area and the corresponding
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l farfield area. The main objectives of the panels program were: (1) to describe the temporal !
l patterns of the dominant organisms that comprise the fouling community, and to determine if !
i any of these organisms have the ability or potential to affect the operation of Seabrook Station, i t
l and (2) to describe the balanced indigenous fouling community in the vicinity of Seabrook Station and determine if the discharge from Seabrook Station has affected this community. The l
program is based on the hypothesis that the local fouling community is not adversely influenced l
by exposure to the thermal plume. Short-term panels, submerged for one month, provided I information on the temporal sequence of settlement activity, while monthly sequential panels, l collected after one to twelve months exposure and quarterly sequential panels collected after three, six, nine and 12 months, provided information on species growth and patterns of community development.
7.2 METHODS 1
7.2.1 Field Methods !
I Fouling panels (10.2 cm x 10.2 cm roughened plexiglass plates, bolted to pine blocks of equal size) were collected monthly from January through December at two mid-depth
, stations (nearfield B19, depth 12.2 m and farfield B31, depth 9.4 m, Figure 7-1). The designation mid-depth was based on the surface to bottom depth in relation to more shallow stations sampled for other programs in this study (i.e., benthos, macroalgae). Panel depths below the water surface ranged from 3 to 6 m depending on the tidal stage. Collections were !
made at Stations B19 and B31 from 1978 to 1984 and from July 1986 through 1995.
Historically, collections were also made at Station B04 from 1978 to 1984 and 1986-1993, and I at Station B34 from 1982-1984 and 1986-1993. Information on these stations is presented in i NAI and NUS (1994).
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i Three different exposure strategies were employed at each station: short-term (ST) panels, exposed for one month; monthly sequential (MS) panels, exposed for increasing time periods from 1-12 months and quarterly sequential (QS) panels exposed three, six, nine and 12 months. Two replicate short-term panels and one monthly sequential panel were collected monthly at each of the stations. In addition to the one MS panel, two QS panels were collected in March, June, September and December for a total of three panels. In December, an additional MS panel was collected at each station.
, 7.2.2 Laboratory Methods ;
6 In the laboratory, each panel was dismantled and the panel face photographed. !
Fouling material wr.s scraped off the wood block and panel support apparatus and rinsed over a !
0.25 mm mesh sieve prior to storage or processing. Wood blocks from all MS and QS panels were dried, split, and examined for the presence of wood-boring organisms. !
All non:olonial species collected monthly on both ST replicates and one December l
, MS replicate were identified and enumerated. When high abundances of Mytilidae, Hiatella l sp. and Anomia sp. occurred, organisms were enumerated from subsamples generated using a Folsom plankton splitter (NAI 1990). Colonial animals, diatoms and macroalgae on ST panels l were quantified by determining the percent frequency of occurrence on the panel face (Mueller- I Dombois and Ellenberg 1974; Rastetter and Cooke 1979; NAI 1990). Colonial animals, diatoms, and macroalgal species were recorded as "P" (present, but not quantified) when found in the sample, but not directly on the panel face. For MS and QS panels, the percent frequency of occurrence of selected dominant animals (colonial and noncolonial), and diatom and j macroalgal species wu estimated using the procedure cited above. Counts were estimated for
- noncolonial species and recorded as an abundance class. Abundance classes, assigned I through 5, consist of ranges of numbers of individuals (1-10,11-100,101-1,000,1,001-10,000, > 10,000, respectively). Colonial and noncolonial dominants, diatoms, and macroalgae were recorded as "P" (present, but not quantified) when found in the sample, but not directly on the panel face. These laboratory methods for MS panels were initiated in 1987.
Random samples of m200 Mytilidae and =100 Jassa mannorata Holmes 1903 individuals found on MS and QS panels and in the residue were measured and recorded in 0.1 7-2
1 mm increments (NAI 1990). All J. marmorata and Mytilidae individuals less than 1.0 mm were recorded as < 1.0 mm and estimated at 0.5 mm in calculations of mean lengths, t
Dry-weight biomass from one of each pair of ST replicates and all MS and QS panels was determined after taxonomic processing by drying all faunal and floral material to a constant weight at 105'C.
b 7.2.3 Analytical Methods Analysis of Variance Recruitment on ST panels, measured on a monthly basis by the number of taxa, the abundance of noncolonial organisms, and total biomass, indicated the potential for fouling community development. Monthly biomass levels on MS panels give an indication of community development. Multiway analyses of variance (variables Preop-Op, Year, Station and Month) were used to compare fouling community settlement patterns (as exemplified by number of taxa, total abundance, total biomass and abundance and size of selected dominant species on ST panels) as well as community development (biomass, dominant species on MS panels) between preoperational (1978-1984 and 1986-1989 for ST panels and MS biomass, 1987-1989 for other MS variables) and operational (1991-1995) years at paired nearfield (B19) and farfield (B31) Stations (the two preoperational periods, 1978-1984 and 1987-1989, were treated as one period and were not statistically compared). Operational /preoperational and nearfield/farfield differences in monthly means for fouling community parameters and ,
abundances of dominant taxa were evaluated using a multi-way analysis of variance procedure i 4
(ANOVA), using a before-after-control-impact (BACI) design to test for potential impacts of plant operation. A fixed effects ANOVA model was used to test the null hypothesis that spatial ;
and temporal abundances during the preoperational and operational periods were not significantly (p>0.05) different. The data collected for the ANOVAs met the criteria of a Before-After/ Control-impact (BACI) sampling design discussed by Stewart-Oaten et al. (1986),
where sampling was conducted prior to and during plant operation and sampling station locations included both potentially impacted and non-impacted sites. The ANOVA was a two-way factorial with nested effects that provided a direct test for the temporal-by-spatial interaction. The main effects were period (Preop-Op) and station (Station); the interaction term (Preop-Op X Station) was also included in the model. Nested temporal effects were years 7-3
i within operational period (Year (Preop-Op)) and months within year (Month (Year)), which were added to reduce the unexplained variance, and thus increased the sensitivity of the F-test.
For both nested terms, variation was partitioned without regard to station (stations combined). -I
! , The final variance not accounted for by the above explicit sources of variation constituted the 1
Error term. Preoperational periods for each analysis e.re listed on the appropriate figures and
, tables. Log (x+1) transformed monthly mean values were used in the ANOVAs for ST noncolonial total abundance and all selected taxa abundances (Jassa marmorata and Mytilidae),
or frequencies of occurrence (Tubularia sp.). Non-transformed monthly means were used in
, the multiway analyses of variance for ST and MS biomass and short-term number of taxa. A l significant difference in the interaction (Preop-Op X Station) was investigated by comparing the l t
- l least square means with a paired t-test (SAS 1985). l l
l t Test i'
t Community development was also assessed by examining biomass, species . '
{ richness, and abundance on surface panels exposed for one year. A comparison was made between preoperational(generally 1982-1984 and 1986-1989, which was treated as one period)
- and operational (1991-1995) periods at each station using paired t tests (SAS 1985). Selected
- dominant species (Mytilidae and Jassa marmorata) lengths from MS and QS panels were also j compared using paired t tests to determine if average annual lengths varied between the nearfield and farfield station pair in 1995, f
t 7.3 RESULTS 7.3.1 Short-Term Panels i Short-term panels provided information on the seasonal cycles of settlement activity. Seasonal cycles in number of taxa in 1995 and during the operational period were -
similar to the preoperational trend (Figure 7-2). The number of taxa typically increased during ;
May and June and remained high throug"h September at both B 19 and B31. In 1995, number of taxa remained high through November at both stations, with the exception of July at B31. Monthly numbers of taxa during the operational period were generally similar to the preoperational period, although several months (May, June, August, October and November at 7-4
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B19 and June, August and October through December at B31) averaged higher than the upper-I '
95% confidence limit of the preoperational monthly means. During 1995, the monthly number i
of taxa was often higher than the preoperational period upper confidence limit, including April, June and August through November at B19 and August through December at B31. During
, several months, February at B19, and January, February and July at B31, the number of taxa in 1995 was lower than the lower 95% confidence limit of the preoperational period. The 4 annual mean number of taxa in 1995, although higher than either the preoperational or operational period mean (Table 7-1), was within the range of previously observed values (NAI l 1
1992). Based on ANOVA, the number of taxa was significantly higher during the operational period than the preoperational period (Table 7-2). ANOVA results indicated that the number !
of taxa at B19 was significantly higher than the number of taxa at B31 (Table 7-2). The interaction term (Preop-Op X Station) was not significant, indicating that the between-station .
difference occurred during the preoperational and operational periods, and was unlikely related to plant operation.
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Seasonal patterns of faunal abundance for non-colonial species at mid-depth Stations B19 and B31 during the operational years, including 1995, were similar to those during preoperational years. Historically, abundances remained low from January to May, increased in June and July, then declined from August to December (Figure 7-2). Mean abundances at both stations during 1995 were greater than the preoperational and operational l
_ period means, prunarily due to the elevated abundances during June through November (except July at B31), which were above the preoperational 95 % confidence limits (Table 7- 1, Figure 7-2). ANOVA results indicated that the interaction of the main effects (Preop-Op X Station) was significant; a significant increase in abundance between preoperational and operational -
periods occurred at Station B19, but there was no significant difference at B31 (Table 7-2, Figure 7-3). Historically, there has been an increase in total abundances every three to four years (Figure 7-4). These periodic increases have been observed at both stations. Abundances
, j in 1994 and 1995 were lower than in 1993, suggesting that a similar pattern is being repeated in the operational period. The significant ANOVA results, which only test operational and preoperational averages, are not indicative of plant effects. l Seasonal settling patterns for the entire fouling community (motile fauna, colonial i organisms, macroalgae) were also assessed by examining changes D Jomass. The 1995 seasonal trend for biomass at Station B19 followed a pattern generally similar to the
[ preoperational and operational periods, except that August and October values were unusually 7-5
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l high (Figure 7-2). Biomass remained low through July in 1995, peaked in August and October
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and then decline
- steadily through December. The unusually high biomass values in August l 1
and October 1995 at B19 resulted in an annual mean value that was twice the means of both the preoperational or operational periods (Table 7-1).
l At farfield Station B31, the operatbnal period biomass levels remained low l throughout the year. Only in November were mean operational period biomass luels above the 95% confidence levels established during the p coperational period. During 1995 at Station l B31, biomass levels remained low through July, peaking in August (4g/ panel) and remaining at l or above preoperational period means through October (Figure 7-2). November and December i values were consistent with operetional and preoperational periods. Annual mean biomass for f 1995 at both stations was higher than preoperational and operational means (Table 7-1) because I of the higher than normal August and October peaks observed at both stations. ANOVA results indicated, however, there were no significant differences for the main effects (Preop-Op and Station), and the interaction of the main effects (Preop-Op X Station) was not significant (Table 7-2).
. Several dominant taxa on short-term panels were monitored to determine their i
seasonal settlement patterns. Historically, Mytilidae (mainly Mytilus edulis Linn61758 spat) was the most abundant noncolonial taxon. Seasonally, the recruitment pattern for Mytilidae during 1995 at Stations B19 and B31 closely followed the operational and preoperational seasonal trends (Figure 7-5). Low to moderate settlement occurred from January to May.
Settlement increased in June and remained high until late fall, following the pattern of larval l availability (Section 4.0). The 1995 monthly abnad-e at Station B19 were higher than the ;
L operational and preoperational averages during July, August and October (Figure 7 5).
O Monthly abundances at Station B31 in 1995 were higher than operational and preoperational means during June, August and October. Annual mean abundances at Stations B19 and B31 in i
i 1995 were higher than their respective preoperational and operational averages (Table 7-1). j ANOVA results indicated that there was a significant interaction between the main effects (Preop-Op X Station). Similar to noncolonial abundance, Mytilidae abundance showed a significant increase between the preoperational and operational periods at B19, but no significant increase occurred at B31 (Figure 7-3). Mytilidae abundance, a major contributor to the observed trends in total abundance, has undergone a three to four-year abundance cycle unrelated to plant operation (Figure 7-4).
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. i The amphipod lassa marmorata (formerly known as J.falcata and revised by l Conlan (1990)) is a common fouling organism (Barnard 1957). This species lacks a larval stage, so recruitment occurs through dispersal ofjuveniles or adults through the water column 1 (Bousfield 1973). Throughout the study period, J. marmorata abundances et B19 and B31 were low during the early part of the year with a small late-summer increase (Figure 7-5). !
This seasonal rectuitment pattern also occurred in 1995. However, abundances at both stations I were above the upper 95% confidence limits of the preoperational period means from August through November. Annual mean abundances in 1995 were higher than the preoperational and
, operational means (Table 7-1) Based on ANOVA, there were no significant differences between the preoperational and operational periods, but abundances were significantly higher at B31 than B19 (Table 7-2). The interaction term was not significant, indicating that the pattern between stations was consistent between the preoperational and operational periods, and there was no effect due to the operation of Seabrook Station.
l Hydroids of the genus Tubularia are dense summer colonizers. They are important as habitat formers and provide a substrate (Field 1982) and food source (Clark 1975) for epifaunal taxa. During the preoprational period, Tubularia sp. increased rapidly beginning in June and reached peak cover in September (Figure 7-5). During 1995, peak percent cover occurred at both B19 and B31 from August through October when percent frequencies were 100% and above the upper 95% confidence limits of the preoperational years. Because of the i
extended and extremely elevated peak period at both stations,1995 annual means were higher l than either preoperational or operational means (Table 7-1). There was no significant j
. difference for the main temporal effect (Preop-Op; Table 7-2). Percent frequency was significa':tly higher at Station B19 than Station B31 for the entire study period (Table 7-2). The interaction of the main effevs (Preop-Op X Station) was not significant indicating no effect due l ., to the operation of Seabrook Station (Table 7-2).
>5 l 7.3.2 Monthly Sequential Panels Monthly sequential panels provide information on cumulative growth and succes-i, sional patterns of development within the fouling community. Seasonal patterns of community development were assessed by examining monthly biomass levels. At Stations B19 and B31 i during the operational and preoperational periods, monthly biomass on monthly sequential l panels remained low from January to June, increasing from July to a peak in late fall / winter 7-7
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1 (Figure 7-6). During 1995, biomass followed this same general pattern, although Station B31 experienced a slight decline in October. On an annual basis, the 1995 mean biomass at both stations was lower than either preoperational or operational means (Table 7-1). Historically {
there has been high year-to-year variability in mean biomass as is indicated by the high I coefficient of variation (CV) at each station during the preoperational period (Table 7-1).
There were no significant differences between the preoperational and operational periods, l
between stations, and no significant interaction of these main effects (Table 7-3). I I
Seasonal patterns of abundance of the community dominants in 1995 were similar l
- j. to those observed during the preoperational period in most cases. Mytilidae spat settled heavily I I
on panels in June at both stations (Figure 7-6). Peret hquer.cy of occurrence during 1995 reached high levels in July thu were maintained tt ,a December at both stations. During the operational period Mytilidae monthly percent frequencies of occurrence were similar to !
t monthly means during the preoperational period.
l Mytilidae spat measurements from monthly sequential panels in 1995 were com- !
pared to determine if mean lengths differed between the nearfield-farfield station pair.
Mytilidae annual mean lengths averaged 3.0 at Station 19 and 2.9 mm at Station 31 in 1995 l
(Table 7-4), and were not statistically different based on a paired t-test (t=0.1, p>0.9).
l Jassa marmorata percent frequency at Station B19 during the preoperational period was quite variable seasonally. This variability has continued throughout the operational period
, (Figure 7-7). However, in general, frequency of occurrence at B19 has been low from January l
to June followed by an increase in August through October and a slight decrease at the end of the year. Percent frequency followed this pattern at B19 during the operational period, and in 1995. The farfield Station B31 exhibited a more distinct mid-year peak in both the preoperational and operational periods. In 1995, there was little decline in frequency at B31 at the end of the year. The operational period was similar to the preoperational period although there were several instances in 1995 (August at B19; September, November and December at i B31) when percent frequency was above preoperational confidence limits (Figure 7-7). The average length of J. marmorata individuals colonizing monthly sequential panels was 3.6mm at !
- B19 and 3.5mm at B31 in 1995 (Table 7-4). A t-test indicated that there were no significant l
! differences in length between the nearfield (B19) and farfield (B31) stations (t=0.1, p > 0.8). l l
7-8 1
~
i i
f In 1995, Balanus sp. (including Balanus spp, and Semibalanus balanoides L.) was first found at Stations B19 and B31 in April, similar to previous years (Figure 7-7). Monthly percent frequencies in 1995 were high (> 60%) at both stations during June through August, m
^
contrast to the lower preoperational monthly means. With few exceptions, the operational monthly means at both stations were greater than the preoperational means but within the established 95% confidence limits.
I During the preoperational period, Tuhularia sp. generally first occurred in April at both stations, with the seasonal pattern of occurrence quite variable from year to year, as l
evidenced by the wide 95 % confidence intervals (Figure 7-7). In 1995, Tubularia sp. first i appeared during the summer at both stations. At B19, frequencies were higher than the preoperational 95% confidence limits during September and November. At Station B31, '
Tubularia sp. occurred only in July and October through December. During the operational period, Tubularia sp. has occurred later in the year (July at both B19 and B31) than during preoperational years.
Fifteen specimens of the woodboring " shipworm", Teredo sp., were found on the MS and QS panel blocks at Station B19 in October, November and December and at Station l B31 in October and December (NAI 1996). Teredo sp. individuals have been recorded from MS panels several times in the past, at Station B19 in 1976 (NAI 1977) and 1979 (NAI 1981a) and at Station B31 in 1980 (NAI 1981b).
7.3.3 Ouarterly Sequential Panels 3
Quarterly sequential (QS) panels provide additional information on growth and l successional patterns of development within the fouling community, and through panel
']
replication, allow assessment of within-station variability. Comparisons can be made with the i preoperational period by using the monthly preoperational mean from the MS panel program for those months sampled in the QS program (Figure 7-7). Quarterly biomass levels were used to assess patterns of community development. !
During 1995, biomass levels were first measurable in June and increased in September at both Stations B19 and B31; biomass continued to increase in December at B19 while decreasing at B31 (Figure 7-8). This seasonal trend paralleled those observed in ST 7-9
. _ . . _ . . - - - - - .. -~,_ - - - _ - . - .. - - -- - . - ---
panels (Figure 7-2) and MS panels (Figure 7-6) both in 1995 and during the preoperational ,
period. The annual average biomass in 1995 was higher than observed for MS panels (Table 7-
- 1) and higher than in 1994 (NAI 1995). The nearfield and farfield biomass values were similar in 1995. .
The number of taxa on QS panels in 1995 averaged 19.5 at Station B19 and 18.5 at Station B31 (Table 7-1), similar to the number observed in 1994. The number o rtaxa on QS l
- panels averaged higher than on ST panels, reflecting the longer exposure period of the QS l
panels. There were 22 taxa present on the December QS (12-month exposure) panels at both stations, compared to 19 at Station B19 in 1994 and 14 at Station B31. The increase in number of taxa observed in December 1995 compared to 1994 was also noted in the long-term panels (Section 7.3.4).
l l
i No Iominaria sp. blades were collected on QS panels in 1995 (Table 7-1), as in l
l 1994. While lominaria sp. blades were present on the December MS (12-month exposure ,
j period) panels at both stations, they occurred in relatively low numbers.
Seasonal pattraus of abundance of dominant animals on QS panels were examined in 1995. Mytilidae were not present during March but were present during the last three quarters with percent frequencies between 50% and 100% at both stations (Figure 7-8).
Seasonal patterns in 1995 were similar to those observed durbg the preoperational period. In 1995, Jassa marmorata frequency of occurrence was low in March and June, but reached 25 %
or higher for the rest of the year at both stations. J. marmorata first appeared in June at both stations and reached a high in September at B19 and in December at B31. Frequencies in September and December 1995 were higher than the preoperational average at both stations (Figure 7-9). In 1995, Balanus sp. first appeared and peaked in June at both stations followed j by a decline (Figure 7-9). Peak percent frequencies in 1995 (approximately 35% at B19 and 55% at B31) were lower than those observed during 1994 but higher than during the l
l preoperational period. Tubularia sp. appeared and peaked in September at both Stations B19 l- (35 %) and B31 (20%) (Figure 7-9). While peak occurrences were higher than observed during the same months preoperationally, they were lower than the peaks observed on MS panels in 1995 (Figure 7-7). The quarterly sampling regime misses the mid-summer months when the
! preoperational average has been highest on MS panels (Figure 7-7),
i 7-10
1 Mytilidae spat and /assa marmorata measurements from QS panels in 1994 were compared to determine if mean lengths differed between the nearfield/farfield station pair.
Mytilidae annual mean lengths averaged 4.2 mm at Station B19 and 3.3 mm at Station B31 (Table 7-5). This difference was not significant (t=-0.32, p>0.7). Average lengths of J.
marmorata individuals +olonizing QS panels averaged 2.6 mm at Station B31 and 2.8 mm at I Station B19. There was no significant difference in length between the two stations (t=0.30, p>0.7).
1
)
1 7.3.4 One Year Panels i l
Community development was also assessed by examining biomass, species richness (number of taxa) and abundance on surface panels exposed for one year. Year-end biomass in 1995 at B19 was similar to the preoperational mean, whereas biomass at B31 was lower than the preoperational mean (Table 7-6). The values at both stations were elevated from the 1994 operational period lows (NAI 1995). Mean year-end biomass during the operational period was not significantly different from the preoperational mean at either Station B19 or B31 (Table 7-6).
The number of noncolonial taxa in 1995 was higher than the preoperational mean at Stations B19 and B31 (Table 7-6). The operational mean was significantly greater than the preoperational mean at Station B19, while there were no significant differences between the preoperational and operational means at Station B31. The number of noncolonial taxa at B19 was similar to 1994 and, at B31, was double that found in 1994 (NAI 1995). At both stations, the number of taxa in 1995 was lower than the average for the operational period (Table 7-6).
Non-colonial abundance in 1995 was higher than both the preoperational and operational mean abund=> at B19 (Table 7-6). At B31, abundance in 1995 was higher than the preoperational mean, but similar to the operational mean. There were no significant differences between the preoperational and operational means at either station. Mean noncolonial abundance at the farfield station was higher than at the nearfield station during the operational period, consistent with the relationship between the preoperational means. I Laminaria sp. blade counts on one-year panels have been low during most years of l this study. At nearfield Station B19 Iominaria sp. did not occur during three of the seven 7-11
t l
preoperational years (NAI 1991,1992,1993) and has not occurred during any operational year until 1995 (Table 7-6). Lominaria sp. did occur during each preoperational year and early j operational years at farfield Station B31, but was absent during 1993 and 1994 (NAI 1995; 1
NAI and NUS 1994). Differences between operational and preoperational means were significant only at farfield Station B31.
7.4 DISCUSSION The surface panels program was established to document the temporal and spatial l patterns in the recruitment and development of the fouling community and to monitor the l effects of Seabrook Station's operation on the community. The characteristics of Seabrook l Station's thermal plume have been estimated from hydrothermal modeling studies (Teyssandier i
et al.1974) and confirmed in recent field studies (Padmanabhan and Heckler 1991). Results from field studies generally confirmed initial model results, indicating that the discharge plume area was relatively small under the conditions tested. For example, the isotherm of a surface temperature increase of 3*F (1.7'C) covered a relatively small 32-acre area in the vicinity of the discharge area. Water temperatures were elevated at most by 2-3*F (under the conditions tested) in the approximate area where panels at nearfield Station B19 are deployed.
L l
The community settling and developing on surface panels has shown predictable seasonal patterns throughout the study, as evidenced by both measures of community structure (biomass, abundance, and number of taxa) and abundance or percent frequency of occurrence of dominant taxa. During 1995, abundance varied seasonally on ST panels and biomass varied seasonally on both ST and MS panels. Biomass exhibita. .imilar trends at nearfield and g farfield stations on both ST and MS panels. Temporal patterns of total and Mytilidae (the most abundant taxon) abundance differed significantly between the nearfield and farfield stations (Table 7-2, Figure 7-4). Historically (Figure 7-3), there has been a pattern of fluctuating total and Mytilidae abundances repeated over a several year period, suggesting that this difference is not indicative of plant effects. The number of taxa on ST panels was higher during the operational period than preoperationally. This pattern was consistent between stations and is, therefore, not related to the operation of "Seabrook Station. In most cases, the operational means closely followed the historical patterns established during the preoperational period (Table 7-7), indicating that settlement and development of the local fouling community remains unaffected by the operation of Seabrook Station.
7-12 l
l The year-end values for parameters measured for surface panels exposed for twelve months provide information on long-term successional development of the fouling community and reflect cumulative effects of biological processes such as recruitment, growth, and -
competition. One parameter, number of non-colonial taxa, showed a difference during the
' operational period that was not consistent between the nearfield-farfield station pair (Table 7-7).
The mean number of non-colonial taxa was significantly higher at Station B19 (nearfield) l- during the operational period. Although the number of taxa was higher at the farfield station,
- this difference was not significant. The same pattern was observed in 1994 (NAI 1995) and a j i
sumlar trend was observed in 1993 (NAI and NUS 1904),' where significant differences were noted at both stations. The algal species Imninaria sp. was present in 1995 at both stations, although it continued to occur at low levels, reflecting the declining trend that began during the preoperational years (NAI, 1991,1992,1993,1995, NAI and NUS 1994). However, the differences in abundance of faminaria between the preoperational and the operational periods were significant only at the midwiepth farfield Station B31. There is no indication that this effect is due to Seabrook Station operation, since the decline occuned at both nearfield and farfield stations and began prior to the operation of Seabrook Station.
The quarterly sequential panel program was initiated in 1994 to provide information on within-station variability of settlement and development. Given the varying exposure period (3,6,9, and 12 months), the program parallels that of the community development (1-12 months exposure, MS) proitratn. The methodology used is similar to the MS program, relyi.ng on percent frequencies for dominant taxa. Quarterly biomass values were i similar to those observed in the MS program in 1995. The atypical fall decrease observed in MS and QS biomass levels in 1994 was not observed in 1995 when biomass returned to a more typical seasonal pattern. Selected species Mytilidae, Balanus sp. and lassa marmorata
- collected in the QS program showed similar seasonal patterns and frequencies to the MS program, as would be expected. Tubularia sp. frequencies typically display a seasonal pattern
in the MS program that is not consistently detected by the QS program. QS panel analyses demonstrate within-station variability was high for all parameters, a factor which should be taken into account in interpretation of MS and ST results.
The occurrence of the shipworm Teredo sp. in 1995 in QS and MS wooden blocks
- that support surface panels is not unexpected for the Seabrook area. Occasional specimens I
have been collected previously during the surface panels study, including 1976 and 1979 at i
I 7-13 i
i 4
Station B19 and 1980 at Station B31 (NA! 1977,1981a, b). Addit.onally, teredinid veliger l
larvae have been observed in bivalve larvae samples every year since 1984.
i Teredo navalis is the most common teredinid reported for the Gulf of Maine (Grave 1928; Turner 1966), and is cosmopolitan in its distribution, being found in most semi-tropical t
to boreal ocean environments (Gosner 1971). Along the east coast of North America, it occurs a
from Newfoundland to Florida (Culliney 1975). While T. navalis is most abundant in
- j. - temperat: and semi-tropical waters south of Cape Cod, periodic outbreaks have been reported js in more northern boreal waters, including the Gulf of Maine (Dow and Baird 1953). The mode j of dispersion is through the larval stage; veliger larvae are planktonic for 2-3 weeks following release from the adult and can travel in ocean currents for hundreds of kilometers (Scheltema f 1971; Nair and Saraswathy 1971). l Based on the historic documentation of Teredo in the Gulf of Maine by other researchers and in the Hampton-Seabrook area specifically during preoperational study years of
- these monitoring studies, and the fact that Teredo sp. was identified at both nearfield anxi
, farfield stations in 1995, the most recent occurrence in 1995 QS and MS panels is not indicative of an impact from Seabrook Station operation.
i Overall, results in 1995 agree with those from previous years. There is no evidence that operation of Seabrook Station has had an effect on the local fouling community.
1 Y
i l
1 l
7-14 ;
)
..~
7.5 REFERENCES
CITED Barnard, J. Laurens. 1957. Amphipod crustaceans as fouling organisms in Los Angeles-Long Beach Harbors, with reference to the influence of seawater turbidity. California Department of Fish and Game. Contribution No. 212. Allan Hancock Foundation. !
Bousfield, E.L.1973. Shallow-Water Gammaridean Amphipoda of New England. Comstock Pub. Ithaca, NY. 312 pp.
Clark, K.B.1975. Nudibranch life cycles in the northwest Atlantic and their relationship to the ecology of fouling communities. Helgo. Wiss. Meere. 27-28-69.
Conlan, Kathleen E.1990. Revision of the crustacean amphipud genus Jassa Leach (Corophiodea; Ischyroceridae). Can. J. Zool. 68:2031-2075.
Culliney, J.L.1975. Comparative larval development of the shipworms Bankia gouldi and Teredo navalis. Mar. Biol. 29:245-251.
Dow, R.L. and F.T. Baird, Jr.1953. Methods to reduce borer damage to lobster traps. Tech.
Bull. No. 3. Dept. Of Sea and Shore Fisheries. Augusta, Maine.15 pp.
Field, B. 1982. Structural analysis of fouling community development in the Damariscotta River estuary, Maine. J. Exp. Biol. Ecol. 57:25-33.
Gosner, K.L.1971. Guide to Identification of Marine and Estuarine Invertebrates. Wiley-Interscience. John Wiley and Sons, Inc. 693 pp.
Grave, B.H.1928. Natural history of shipworm, Teredo navalis, at Woods Hole Massachu-setts. Biol. Bull. Woods Hole 55:260-282.
Mueller-Dombois, D., and H. Ellenberg. 1974. Aims and Methods of Vegetation Ecology.
John Wiley & Sons, NY. 547 pp.
Nair, N.B. and M. Saraswathy.1971. The biology of wood-boring teredinid molluscs. Adv.
Mar. Biol. 9:335-509 i l
Normandeau Associates Inc.1977. Seabrook Benthic Report. 1987. Tech. Rep. VII-6.
.1981a. Seabrook Environmental Studies.1979 Seabrook Benthic Report.
Tech. Rep. XI-5.
.1981b. Seabrook Environmental Studies.1980 Data Report. Tech. Rep. XII-2. !
.1988. Seabrook Environmental Studies.1987. A characterization of baseline .
conditions in the Hampton-Seabrook area. 1975-1987. A preoperational study for l Seabrook Station. Tech. Rep. XIX-II.
.1990. Seabrook Environmental Studies.1989 Data Report. Tech. Rep. XXI I.
l 7-15
. - - _ . _ _ - _ . -- ~_ -. - .- . - . - - . . - - . . - _ - . _ - -
~
i
,1991. Seabrook Environmental Studies,1990. A characterization of environ- !
mental conditions in the Hampton-Seabrook area during the operation of Seabrook Station.
Tech. Rep. XXII II.
.1992. Seabrook Environmental Studies,1991. A characterization of envi-ronrnental conditions in the Hampton-Seabrook area during operation of Seabrook Station.
Tech. Rep. XXIII-I. ,
,. .1993. Seabrook Environmental Studies,1992. A characterization of environ-
!- mental conditions in the Hampton-Seabrook area during the operation of Seabrook Station.
l Tech. Rep. XXIV-I.
l L .1995. Seabrook Environmental Studies,1994. A characterization of environ-mental conditions in the Hampton-Seabrook area during the operation of Seabrook Station.
l Tech. Rep. XXV-1.
.1996. Seabrook Environmental Studies,1995 Data. Unpublished data tables.
Normandeau Associates (NAI) and Northeast Utilities Corporate and Environmental Affairs
- (NUS).1994. Seabrook Environmental Studies,1993. A Characterization of Environ- '
l mental Conditions in the Hampton-Seabrook Area During the Operation of Seabrook Station. Prepared for North Atlantic Energy Service Corporation.
Padmanabhan, M., and G.E. Hecker. 1991. Comparative evaluation of hydraulic model and field thermal pitme data. Seabrook Nuclear Power Station. Alden Res. Lab., Inc. 12 p.
l Rastetter, E.B., and W.J. Cooke. 1979. Response of marine fouling communities to sewage i
abatement in Kaneohe Bay, Oahu, Hawaii. Mar. Biol. 53:271-280.
I SAS Institute, Inc. 1985. User's Guide: Statistics, Version 5 Edition. SAS Inst. Inc. Cary,
- NC 956 pp.
Scheltema, R.S. 1971. Dispersal of phytoplanktotrophic shipworm larvae (Bivalvia:
Teredinidae) over long distances by ocean currents. Mar. Biol.11:5-11.
Stewart-Oaten,A., W.M. Murdoch and K.R. Parker.1986. Environmental impact assessment:
"Pseudoreplication in time?, Ecology. 67:920-940.
- Teyssandier, R.G., W.W. Durgin, and G.E. Hecker. 1974. Hydrothermal studies of diffuser discharge in the coastal environment: Seabrook Station. Alden Res. Lab. Rep. No. 86-24.
Turner, R.D.1966. A Survey and Illustrated Catalogue of the Teredinidae (Mollusca:
Bivalvia). The Museum of Comparative Zoology, Harvard Univ., Cambridge, Mass.
265 pp.
l
{
f 7-16
TABLE 7-1. MEANS (PER PANEL) AND COEFFICIENT OF VARIATION (%) FOR SELECTED PARAMETERS AND SPECIES ABUNDANCES AT STATIONS B19 AND B31 DURING THE PREOPERATIONALS AND ,
OPERATIONAL PERIODS (1991-1995), AND 1995 MEANS. SEABROOK OPERATIONAL REPORT,1995.
PREOPERATIONAL' 12M OPERATIONAL I
PARAMETER / PANEL" TAXON TYPE STATION MEAN' CV MEAN' MEAN' CV ST B19 11.3 30.4 15.1 13.6 13.3 Totalno.of taxa 4.8 B31 10.8 25.2 12.3 12.4 ST B19 53.7 17.2 101.7 79.5 11.8 Totalnoncolonial abundance B31 69.9 18.2 74.4 67.4 14.1 ;
ST B19 0.8 40.8 1.7 0.8 74.5 Totalbiomass (g) B31 0.6 67.5 0.9 0.6 54.4 ST B19 30.4 22.6 60.1 45.0 18.8 Mytilidae 23.5 39.9 B31 39.6 21.1 54.0 Jassa marmorata ST B19 3.0 29.0 8.6 2.9 37.9 B31 3.9 30.4 12.1 4.2 41.3 Tubularia spp. ST B19 1.9 51.2 3.6 2.2 21.2 B31 1.1 73.6 3.2 1.0 89.0 Biomass MS B19 207.8 106.6 172.1 197.2 49.3 ;
(g) B31 236.8 90.0 141.1 193.6 36.3 Biomass QS B19 - - 237.8 194.6 -
(g) B31 - - 259.6 208.3 -
Totalnumber of taxa QS BI9 - - 19.5 20.8 -
B31 - - 18.5 17.3 - .
Laminaria sp. QS B19 - -- 0 0 -
B31 - - 0 0 -
'ST = short term MS = monthly sequential AS = quarterly sequential 6Preoperational = 1978-1984; Jul 1986-Dec 1989 h.caic mean for total abundance, Mytilidae,J. marmorata abundance and percent frequency ofoccurrence for Tubularia sp. Preop. and Op. means are means of annual means.
i
- .u ,
- a
.t i
TABLE 7-2. RESULTS OF ANALYSIS OF VAC.IANCE COMPARING MONTHLY TOTAL NUMBER GF TAXA, !
I NONCOLONIAL FAUNAL ABUNDANCE, TOTAL BIOMASS, AND SELECTED SPECIES ABUNDANCE OR PERCENT FREQUENCY ON SHORT TERM PANELS AT THE MID-DEPTH STATION PAIR (B19 AND B31)
DURING PREOPERATIONAL(1978-1989) AND OPERATIONAL (1991-1995) PERIODS. SEABROOK '
OPERATIONAL REPORT,1995. i SOURCE OF MULTIPLE VARIATION di S IF COMPARISONS' i PARAMETER STATIONS Number of taxa B19,B31 Preop-Op= 1 305.10 47.58 "
- Op> Preop Year (Pre @)* 14 128.96 20.11 "
- Month (Year)' 166 86.11 13.43* "
Station' 1 50.55 7.88 *
- B19)B31 Preop-Op X Station
- 1 11.12 1.73 NS Error 180 6.41 Noncolonial faunal abundance B19,B31 Preop-Op 1 039 4.51' Op> Preop Year (Preop-Op) 14 1.57 I8.10***
Month (Year) 166 2.43 27.99' "
Station 1 0.05 0.57 NS Preop-Op X Station 1 0.69 7.97 " B190p B31 Preop B31On B19 Preop Error 180 0.09 Biomass B19,B31 Preop-Op 1 0.43 0.47 NS Year (Preop-Op) 12 2.56 2.79* ?
Month (Year) 146 2.79 3.05 *"
Station 1 3.02 3.30 NS Preop-Op X Station 1 0.01 0.01 NS Error 158 0.92 Mytilidae B19,B31 Preop-Op I 0.50 4.81* Op> Preop Year (Preop-Op) 14 2.14 20.85 "
- Month (Year X Preop) 166 2.86 27.49 "
- Station 1 0.08 0.79 NS Preop-Op X Station 1 0.56 538' B190o B31Preon B31On B19 Preop Error 180 0.10
SOURCE OF MULTIPLE STATIONS VARIATION df S l' COMPARISONS 8 PARAMETER Jassa marmorata B19,B31 Preop-Op 1 <0.01 0.0I NS Year (Preop-Op) 14 0.87 9.79'"
Month (Year X Preop) 166 0.82 9.18" * ,
Station 1 0.92 10.34 " B31>B19 Preop-Op X Station 1 0.05 0.53 NS Error 180 0.09 ,
Tubularia sp. B19,B31 Preop-Op 1 0.01 0.04 NS Year (Preop-Op) 14 0.9I 6.32"
- i Month (Year X Preop) 166 0.75 5.23 "*
Station 1 2.06 14.32 "
- B19>B31 Preop-Op X Station 1 0.08 0.53 NS Error 180 0.14
' Preop-Op = 1991-1995 v. previous years (1978-84; July 1986-December 1989) regardless of station j
' Year nested within preoperational and operational periods regardless of station
' Month nested within year regardless of station i
- Station regardless of year or period
(
' Interaction between main effects Station and Preop-Op
'NS = Not significant (p>G.05) i
- = Significant(0.05mp>0.01)
" = Highly significant (.01 a p>0.001) >
- " = Very highly significant (0.0012 p)
' Ranked in decreasing order LS means multiple means test used for significant interaction term I
I
- s TABLE 7-3. ANOVA RESULTS COMPARING MONTHLY SEQUENTIAL PANEL BIOMASS AT THE MID-DEPTH (B19, B31) STATION PAIR DURING PREOPERATIONAL (1978-1989) AND OPERATIONAL (1991-1995) PERIODS. SEABROOK OPERATIONAL REPORT,1995.
SOURCE OF STATIONS VARIATION df MS F Mid-depth Pre W l 4,756.22 0.42 NS B19,B31 Year (Preop-Op)* 14 276,118.10 24.61 "
- Station- 1 6,395.16 0.57 NS Month (Year)* 156 129,656.88 11.55 "
- Preop-Op X Station
- 1 38,260.42 3.4i NS Error 170 11,221.74
- Preop-Op = 1991-1995 v. previous years (1978-84; July 1986-December 1989) 6 Year nested within preoperational and operational periods regardless of station
' Station regardless ofyear or period
- Month nested within year regardless of station
' Interaction between main effects HS= Not significant (.05>p)
- = Significant (.01<ps.05)
" = Highly significant (.001<ps.01)
"* = Very highly significant (ps.001) l l . -_ -- -. - _ - - _ _ - - - _ - _ _ _ - - - - _ - - - _ --- _ _ --- - - - - _ - - _ - _ - - - - - - - _ _ - - _ - - _ - - - _ - - - -
t a
TABLE 7-4. NEARFIELD/FARFIELD COMPARISON OF ANNUAL MEAN AND STANDARD ERROR OF JASSA MARMORATA AND MYTILIDAE SPAT LENGTHS (mm) FROM MONTHLY SEQUENTIAL PANELS COLLECTED IN 1995. SEABROOK OPERATIONAL REPORT,1995.
MYTILIDAE SPAT JASSA MARMORATA STATION MEAN STANDARD MEAN STANDARD l
LENGTH ERROR LENGTH ERROR i (mm) (mm)
Mid depth B19 3.0 0.97 3.6 0.48 B31 2.9 0.94 3.5 0.43 I
l l
l l
P
l TABLE 7-5. NEARFIELD/FARFIELD COMPARISON OF AhWUAL MEAN AND l STANDARD ERROR OF MYTIL10 AE SPAT AND JASSA M4RMORATA LENGTHS (mm) l FROM QUARTERLY SEQUENTIAL PANELS COLLECTED IN 1995.
I SEABROOK OPERATIONAL REPORT,1995.
1 MYTILIDAE SPAT JASSA MARMORATA 1-MEAN LENGTH STANDARD MEAN LENGTH STANDARD STATION (mm) ERROR (mm) ERROR B19 4.2 2.23 2.8 0.55 B31 3.3 1.93 2.6 0.55 5
i i
4 TABLE 7-6. DRY WEIGHT BIOMASS, NONCOLONIAL NUMBER OFTAXA, ABUNDANCE, AND LAMINARIA SP.
COUNTS ON SURFACE FOULING PANELS SUBMERGED FOR ONE YEAR
- AT STATIONS B19 AND B31.
MEAN AND STANDARD DEVIATION FOR THE PREOPERATIONAL PERIOD (1982-1984 AND 1986-1989)
AND MEAN FOR 1995, AND THE OPERATIONAL PERIOD (1991-1995). ;
SEABROOK OPERATIONAL REPORT,1995. l PREOPERATIONAL 1221 OPERATIONAL
- STATION MEAN S.D. MEAN MEAN S.D. i BIOMASS B19 661.5 476.88 601.2 749.1 NS 506.49 (g/ panel)
B31 708.9 523.86 437.4 510.0 NS 271.47 NUMBER OF NON- B19 213 4.42 24.0 29.5
- 4.80 COLONIAL TAXA (Nolpanel) B31 25.9 4.60 30.0 31.0 NS 11.45 NONCOLONIAL B19 13,905.1 7,046.48 77,209.0 41,lll3 NS 34,032.68 ABUNDANCE (Nolpanel) B31 21,967.6 I8,398.27 58,961.0 59,481.8 NS 35,261.04 LAMINARIA SP. 6 B19 243 36.91 1.0 03 NS 0.50 (Nolpanel)
B31 393 29.24 9.0 6.4
- 6.43
- 01<ps.05 when preoperational and operational means tested for equality with a single sample t-test (SAS 1985)
' December MS panel only (one replicate)
'not determined to species due tojuvenile condition of most plants
'B19:1991,1993-1995; B31:1991-1995. B19 panel lost due to weather J
TABLE 7-7.
SUMMARY
OF EVALUATION OF DISCHARGE PLUME EFFECTS ON THE FOULING COMMUNITY IN VICINITY OF SEABROOK STATION.
SEABROOK OPERATIONAL REPORT,1995.
NEARFIELD-FARFIELD OPERATIONAL DIFFERENCES DEPTH PERIOD SIMILAR TO CONSISTENT WITH COMMUNITY ZONE PARAMETER
- PREVIOUS YEARS? PREVIOUS YEARS?6 .
Fouling community: Mid-depth Abundance no NF:Op> Preop Settlement' FF:Op= Preop No. of taxa no yes Biomass yes yes ;
l l
Fouling community: Mid-depth Biomass yes yes Development-MS' ,
Fouling community: Mid-depth Abundance yes yes Development- No. of taxa no NF:Op> Preop l year end' FF:Op= Preop Biomass yes yes Fouling community: Mid-depth Mytilidae no NF:Op> Preop ,
Settlement
- FF:Op= Preop Mid-depth Jassa marmorata yes yes Mid-depth Tubularia sp. yes yes ,
' Abundance, number of taxa, biomass, total density, and frequency of occurrence evaluated using ANOVA, or t-test
- NF = nearfield FF = farfield
' Settlement = short term panels; Development = monthly sequential panels - MS; year end = one year exposure l
l l
i I
j
. ~ . - - - _ . . - - . . . = - - . = _ . _ . ~ . . _ . _ - -. - - _ _ - _ . . . . - . - . . . . - --
. N RYE LEDGE o .....
UTTLE .FARFIELD BOARS AREA *-
HEAD 0 .5 1 Nautical Mile . ..
0 1 2 Kilometers 9 ,
SCALE .:. .
CONTOUR DEPTH 4 .'!
- IN METERS ,.,.
1 0 .
GREA TBOARS j ,
HEAD .
'e HAMPTON i! ,k BEACH .' :
e:
BROWNS -
UVER .
. NEARFIELD
- Intake AREA c..
lbuTER f....'
V t SEABROOK -
V. >
l STATION .
~a ../A....... ' Discharge '
HAMPTON l SEABROOK SUNK -
HARROR ROCKS ,.
l
%% SEABROOK BEACH s . ',
- l \ s s
- V . .
SAUSBURYBEACH
- LEGEND Q = surface panens Figure 7-1. Surface panel sampling stations. Seabrook Operational Report,1995.
i l
i Number of Taxa
!" $ston BS Simlon 531 30 30 _ p,,,,,,,,,
_ f_
-- s CorelorW g l Opassond / 25 "*
25 m. 1M5 /...<
\
g WE f s
[ j*\
f .
- y,.' '\9,
, 20 -
J %w
'.,.,s W l
//pP,
% \
N ' 8, -
. T B #
fi si
/ \ (' ,,,\ s
,s ;//
/ s se -
.s Q
a d' m i 5 , t _
5 --
N# 0.
-;p /,
t 0.
M FEB M M M JUN R M SEP OCT NW De M FEB M M W M R M SEP OCT U DEC MONfH MONIN 1
Log (x+1) Abundance 1
r snson Be mason an j
5- m 6m
.- ep ,,ang 3 4
"* me5
/ \ 4 "* 1se5 e\
1 ,f.-- ....\ ' -s 1
' ' ,T,_ l', \--.Q '
.s
,/(
[ s's.,N., s ,,)x I'2g X.
t's 2 \
j# '
i
,/ !
j' , ~/ l 0 O"--
M FEB M M W M R M SEP OCT NW DEC M FEB M M W AN R AUG SEP OCT NCV Dhc MONIN i MON 1H Biomass Simeon BW Simion B31 10 _ 10 _
__ op,mong g
_p 3
"* 1M5 sg a
"* W l\
8 l '\
o e i
\\
^
a l I / '\ is l<
\ l \
2 Yl jf .
2 0 :_
~
- ~~
0 -
M FEB M M M JUN JUL AUG SEP OCT NW OEC M FEB M M M JUN R AUG SEP OCT NW DEC MONTH MONTH Figure 7 2. Monthly faunal number of taxa (on two relicate panels), abundance, and biomass on short-term panels at the nearfield/
station pair B19 and B31during the operational pedod (1991-1995) and 1995 compared to the means and 95% confidence limits during the preoperational peded (1978-1984; July 1986-December 1989). Seabrook Operational Report,1995.
Total Abundance 3.00 m s ..gg
-- -~
l 2
j
{ 1.s0 126 1
- t !
1.00 0,M
?
OJe 0.00 i emo mons om i emoo l a
l Mytilidae ;
2.00 me, i
1.75
{u0 E un 1
1J00 i? 0.re E-02 DD0 P=op=mune op=*=nw emoo Figure 7 3. A comparison between stations of the logio(x+1) no. per panel total abundance and Mytilidae abimdaner in short term panels during the preoperational(1978 1985; 1987 1989) and operational (1991 1995) periods. Seabrook Operational Report,1995.
l Total Abundance zoo
-. sie gg seo !
" .t l ,. 1 l! !*
ig tao sao
,I \.
l \ a t
l
.! ,\.
M soo ,
l \
t , ,
l.'. . .
l I '. l \ \
! \. . , i eo
\ ',~
\
- l l
\ l
- l :
l \s, >
/ ,
ao l
, , r,
, , .l * %
So i ,
o n n m a a a u a a a a a a m a a u m 1
Mytilidae zoo
- me
- set i
- l iso 140 i
l A .
h*coi l
i '.
/ '.
\
!\
l\ l l ** r : \
l \ ! \
/ a /. l \
oo l \' /\ '
l
/ . l ,
s ao l '\ '
l' \
/ i , N, i so ,,/ ,
,d o
M 79 40 m og as p as as 37 88 80 to a se se H as I
- i t
Figure 7-4. Annual geometric total abundance and abundance of Mytdidae on short-term panels I at Stations B19 and B31,1978-1995. Seabrook Operational Report,1995.
1 1
I
Mytilidce suam se sanan am
' 0 MacpwamW s
_ _ _. Pmopuss,ed o,,, ,. _ _ _ .
4
- E / \ 4
- M
/ \ /\
3
- g 3 f ,
f
,/[/ '"" .. s
/
N .s3 , N
.t 9 .
f 5 i o-
~
o #' '2 ~2>'-
uom m Jassa marmorata l susan se smaan an a s g,,,,,,,,
. _ . e,,,,,, ___. %
E 4 W I4 3 iN 3
~ ' s j ~ n T2 /
'N !2 / ,
\
g '/~~~"Q- g i ' , -' , . . ., .'N.
,w/,- ,a >
m . m a w a a a se oCr a osc M FEB M M M M R M SEP oCf G DEC uom m Tubularia sp.
amen es se am
. _ =; _opemand ,.
li--- ,\
to ---
opemazd so ---- ,--,,t s
a # E I l'. \ m # M l \
i j '.\ .
n
=
l \
m l -
l \
in
- a
. ,llJ/ \.\q'.\
l,l a=
l l
/N\.\
\
i a '/ m- , M k J M FEB M M W M R M SEP oCT p DEC M FEB M M W M R M Se oCT p OEC uom uom Figure 7 5. Log abundance (no. per panel) of Mytilidae and Jassa marmorata and monthly mean percent frequency of Tubularia sp. on short-term panels at nearfield Stations B19 and B31 during the operational period (1991-1995) and 1995 compared to the mean abundance or percent frequency and 95% confidence limits during the preoperational period (1982-1984; July 1986- December 1989). Seabrook Operational Report,1995.
f
l
- 1 I
l l~ Biomass ,
WM hp a ...
w a ....%
a m su n
- 88 ,
i M l M l en no l l
A,%.d->
l ,. / m .- .
e a M/ '.
lm i
a a ,. ...
,.-l / n
=
a l
.4lA/
oi -- oi m e a m w M R a sEP ocr a asc m e e e a M R a er ocr a osc MOMH MOMH Mytilidae swanse men M M r, --"----" 2 ,. e ...
w .. - .
. . ....% m ,ij a * * '
. a *
- j l
- . N I
'l e
ll ,/ e
{
lN a n I ll 4 4 !!
- a *a ll 3 m [
ei ! -
ei - -
M B W M M M R M MP ocT a DEc M M M m a M R M SEP Ocr a DEC EMH WOMH Figure 7-6. Mean biomass (g/ panel) and Mytilidae spat (pen:ent frequency of occurrence) during the operational penod (1991-1995) and in 1995 compared to mean and 95% - Ah limits during the preoperational period (Stations B19 and B31 from 1978-1984 and July-C =-*=
1986-1989 for biomass and 1987-1989 for Mytilidae) on monthly sequential panels. Seabrook
! Operational Report,1995.
- . = . - .. . _ _ _. . . - - _ . - . _ . - . _ _ _ - -
~
. Jasss marmor:ts 1
sum se som a 4
P=esemd monometre i so ---- op mare so ----
w e ++. uns a m m
. n p n
,s e s
e o %-; l % .-
i n l \ m t. ,,
- e s e //
- ea I' - ' K ;%,.y ea , fo ,, ...
m -
/'
r a
i
/
i s ie M ._
a pas a m m a a a w ocr e o m a Pts a m u a a a ser ocr o onc j womH Mom Balanus sp.
sum se swan an 1
80
- pas. mand i
, so . . . . a.op sm,s op,,,, so ---.
w I
- so
- *ss a
- um l n a ....
- a f'...
m ,. /p\ '. .
j m /j \ ,' ....,
so .,
l e j f% '
e , t 1
% /\'
. *m f ' *',/Q ~ l.* * ,
i, , *m ,
,/ j' [ N/ '
8 ,
ef,. / \ N 8 8
jF
/,V b i
- 8 o
fN/ o a pas a m m a a a up ocr a osc m e M a w a a a sur ocr a cac MOMH M0mH i
1
- Tubularia sp.
i sman se aman an m ,,,,,,,,, a-so ---. op ,e,ns . .__.
p
', e
- 888 a m *ss
/,'s n
.- l \ a 1
I**"
- m
,J-. -
/ \
, .'. .'\i
- a 5
=
a \ /,/ a ,-
. .k. / h-~, , ,
W i
s.
o:
- S.. ~
o.
/ =~ A*
Figure 7-7. Mean percent 0wy of occurrence forJassa marmorata, Balanus sp. and Tubularta sp. at Stations
- B19 and B31 during the operational period (1991-1995) and in 1995 coinpared to means and 95%
cehe limits during the preoperational period (1987-1989) on monthly sequential panels. Seabrook Operational Report,.1995.
i
Biomass siamon N stadon 83:
M e+e pmap 900 e+e Pmop g .... g g .... g
-.g _. g l
E0 000 E ,,,,- % ,f ' ~ ~ ~
j
/ MO /,
,.V IO 4.. -
ago
./ f ago go .f n ...
..'/
/
. . /. 's .
l O ,
/ O ,,.*** ,/
o ;- -n o .
M M SEP DEC M M SEP DEC WONTH WONTH Mytilidae Stanon m Stadon est O m ,r 100 m ,,,
m .....g ,',
, 90 -... m ,
a ~~
m .
n - - 1988 l l . .. / cn l j.
' ,2 ..........
ln , l ,. , /l
/ l.,
e !
l '/
p s' e l
ll' Y $ l h &' ll
/.*l a .l 2 it' w s o o N JUN MP DEC M JUN SEP DEC.
MONTH MOdTH Figure 7 8. Mean biomass (g/ panel) and Mytilidae spat (percent frequency of occurrence) and 95%
l cefihe limits (n=3) during 1995 from Stations B19 and B31 on Quarterly Sequential panels compared to the monthly preoperaticaal means (1937 1984 and 19861989 for biomass and 19871989 for Mytilidae). Seabrook Operational Report,1995.
l
Jass2 marmoratz Season SW Susan 831 8 m Preap 20 ,,,p,,,,
90 .... 34 90 .... mg l
t to -- -- Ms m -- M 70 70 80 80
, i 50 40 s
s' ~~ ~~
m 40 s
i
/
g ,/ g ,s' g ,/ ,,......** w J*'
_..............- n
!' M M SEP DEC MUt M SEP CEC L
MONTH HONTH Balanus sp.
l l Smean BW Stanon 831 20 , ,, p ,,,
W ,+ p ,
30 .... gg ,,
90 . . . . -
3 94 / ..
a0 ses ,/ ,' ., e0 ses ,/ .
. 70 /
/ . /
m ;
/
m j
/
\-
Iem70
/
40 /
e 40 i
/ / ~%'~';'...................
i
,f~~~
' ~- ---------
sa a
l' / ~~~~,,'
m , ,< !/
= p = 4' -
m M seP DEC MUt M SEP DEC i MONTH MONTH Tubularia sp.
msnm se ammon est 2 +++ p.op
- j s0 . . . . g, so *++ Pman.
.....g l
70 m e
1e aa m
e
,/\ s s, .., am e
e m ,' m - ~~~.
Ng. -
~ "
.. . . ,,.. Z, m M se oEc uMt M SEP DEC
! uoNm woNM Figure 7 9. Mean percent frequency of occurrence forJassa marmorata, Balanus sp. and Tubularia sp.
at Stations B19 and B31 during 1994 and 1995 compared to the monthly preoperational means and 95% c=% limits (1987 1989) on Quarterly Sequential panels. Seabrook Operational Report,1995.
l I
i
I l~ j i I l'
i EVALUATION OF SEABROOK STATION SURFACE PANELS PROGRAM AFTER FIVE YEARS OF PLANT OPERATION l
l Prepared for l
i NORTH ATLANTIC ENERGY SERVICE CORPORATION P.O. Box 300 Seabrook Station l Seabrook, New Hampshire 03874 l
1 Prepared by
. NORTHEAST UTILITIES SERVICE COMPANY !
Safety, Health & Environmental Services Aquatic Services Branch Waterford, Connecticut 06385-0128 Critical reviews of this technical paper were provided by:
The Seabrook Station Ecological Advisory Committee:
- Dr. John H. Tietjen, Chairman (City University of New York) l Dr. W. Huntting Howell (University of New Hamshire)
Dr. Bernard J. McAlice (University of Maine)
)
L Dr. Saul B. Saila (emeritus, University of Rhode Island)
Dr. Robert T. Wilce (emeritus, University of Massachusetts)
Normandeau Associates,Inc.
25 Nashua Road Bedford,New Hampshire 03310 l
i July 1996 o
4
- Evaluation of Seabrook Station Surface Par, cts Program After Five Years of Plant Operation ,
i I
I I
4 Introduction j n Use of artificial substrata (e.g., exposure panels) is an effective experimental method to study
,? -
marine benthos that occur on hard surfaces. Standardized substrata (size, material and surfice texture, depth and orientation in the water column) are intended to simulate natural hard surfaces, )
while removing factors such as surface heterogeneity and orientation that produce variability naturally associated with the colonization of submerged surfaces (Osman 1977,1982; Sutherland l and Karlson 1977). The capability of deployment at specific locations ensures that panels and l
the developing fouling community are exposed to the desired degree of the stress of interest l
(Brown and Moore 1977; Schoener 1982) and the ability to take exposed panels to the laboratory ,
permits closer examination than is possible in the field (Cairns 1982). Therefore, when i
appropriate, exposure panel studies have been included in many environmental monitoring programs (Cory and Nauman 1969; Hillman 1975,1977; Osman et al.1981; NUSCO 1987; NAI
!+ 1996a).
l ;
l M The surface fouling panels program initated at Seabrook Station in 1975 was designed and implemented with two objectives. The first objective was to determine the composition and characteristics of the local fouling community, identifying species that could settle on power plant I structures and impair their operability. The second objective was to determine if the operation of Seabrook Station affected patterns of fouling species settlement and community development.
4 2 1 i
. , . . - - - - . _ . - - . - . - - - _ . . .- - -. . ~ . . - .
4 The Seabrook Station condenser cooling water discharge could potentially impact the local fouling community in several ways. Changes to water circulation patterns around nearby hard surfaces could affect abundance and species composition of available colonizers. Elevated temperatures could impact the exposed fouling community by affecting rates of recruitment and growth of settled organisms, changing long-term pattems of successional developmert. Finally, 1
the power plant discharge could affect the distribution or behavior of motile grazers and predators
!~
l, l which are important structuring factors in the fouling community. The purpose of this report is to evaluate the current surface panels program to: 1) determine how well the program has l
addressed its two objectives after over 20 years of study that include five years (1991-1995) of Seabrook Station operation; 2) identify any redundancy with other studies of the Seabrook i
monitoring program (such as the marine macrobenthos studies); and 3) determine if any questions remain that would merit continued surface panel rnonitoring.
t I
l l
Review of Methodology i
l l
l' The sampling methodology and data analyses used in the surface panels program were I
P
! designed to focus on key aspects of the fouling community (e.g., community parameters, selected !
J l
l- taxa) at sites determined to be most likely impacted by Seabrook Station operation. A synopsis 1
of the historical development of this program was presented in NUSCO (199.',).
l In the present surface panels program, fouling panels (10.2 cm x 10.2 cm roughened plexiglas i
plates bolted to pine blocks of equal size) have been deployed at two stations: B19 in the 2
e
1 nearfield area near the discharge and B31 in the farfield area (Fig.1). Panel depths below the surface have ranged from 3 to 6 m, depending on the tidal stage. Collections at these stations I s
have been made monthly through 1978-1984 and from July 1986 through 1995. Several panel 3 i
exposure strategies have been employed in the program. Short-term (ST) panels have been deployed monthly for one-month exposure periods over the sampling year (Jan-Dec). All i
- monthly sequential (MS) panels have been deployed at the beginning of the year, and then ;
a collected monthly, resulting in an increasing exposure from one to twelve months. Two replicate short-term panels and one monthly sequential panel have been collected monthly at each station.
Additionally, based on the previous evaluation (NUSCO 1993), a quarterly sequential (QS) panel l 1
program was initiated in the beginning of 1994 as a possible improvement and/or replacement '
of the MS panel program. The new QS panels have provided the sample replication needed to l
l l assess within-station variability. The two QS panels collected every three months (March, June, September, December), and the MS panel collected at the same time in those months, have provided three replicates for the 3, 6, 9, and 12-month exposure periods. Laboratory processing of panels has consisted of taxa identification and abundance determination, dry-weight l biomass, and length measurements for random samples of dominant taxa Mytilidae and Jassa marmorata.
lj lj Multiway analyses of variance with the main effects or classification variables Preop-Op, Year, i
Station and Month have been used to compare fouling community pattems of settlement (based on species richness, total abundance, biomass and abundance of selected taxa on ST panels) and i
development (biomass on MS panels) between preoperational and operational periods. A fixed- l
, effects ANOVA model based on the Before-After/ Control-Impact (BACI) sampling design 1
3
~
discussed by Stewart-Oaten et al. (1986) was used to test for potential impacts of plant operation.
A significant interaction term (Preop-Op X Station) was investigated by comparing least-squares l
l estimates of means. Paired t tests were also used to compare preoperational/ operational period i differences in biomass, number of taxa and abundance on surface panels exposed for one year, and differences in average annual lengths of Mytilidae and Jassa marmorata between nearfield i
and farfield stations. Further details of sampling methodology and data analyses are provided in NAI (1996a).
Results and Discussion Information critical to assessment of fouling conununity impacts related to Seabrook Station operation includes extensive physical and biological data. Hydrodynamic modeling, conducted l
prior to plant start-up to predict the areal extent of the thermal plume under various meteorological and marine current regimes, indicated considerable dilution of thennal effluent once the plume reached surface waters in close proximity to the discharge (AT 4 F ), and that further dilution (AT s2'F ) at the surface would occur within relatively short distances (0.5-1.0 l 1
km) from the discharge area (Teyssandier et al.1974). Subsequent field validation studies were l conducted after Seabrook Station began operation during October-November 1990. This period l was chosen because there was no vertical temperature stratification, similar to conditions used in the hydrodynamic model. Conclusions from these studies were consistent with modeling predictions, and estimated the area within the 3"F AT isotherm to be a relatively small 32 acres 4
t I
9
~
of surface water near the discharge (Padmanabhan and Hecker 1991). Based on both studies, surface panels at the nearfield B19 station were exposed to a maximum AT of 2-3' F (Fig. 2).
l Temperature increases at the nearest potentially-exposed natural hard substrate habitats were <l'F (i.e., at the intertidal and shallow subtidal sites near the Outer Sunk Rocks monitored through marine macrobenthos studies (NAI 1996b)).
l Analyses of biological data collected during the surface panels program have shown very consistent patterns of fouling species settlement and community development over the entire study period, including the first five years (1991-1995) of Seabrook Station operation (NAI 1996a). Assessment of seasonal settlement patterns was based on results of the short-term panels :
1
! study. While ANOVAs indicated significant differences among months and years, and between stations for community indices and abundances of dominant taxa, the Preop-Op X Station l interaction term was significant for only two parameters (Total noncolonial abundance and i
Mytilidae abundance; Table 1). In both cases, increases from the preoperational to operational period were observed at the nearfield station (B19), while no between-period changes were observed at the farfield station (B31).
To further investigate these apparent increases in abundance since 1990 in the nearfield area, the nonparametric Wilcoxon's signed-rank test (Lehmann 1975) was used to compare nearfield I
and farfield monthly time-series. This test provided strong support to the ANOVA results by concluding that there were significant differences between nearfield and farfield stations (B19<B31) for total non-colonial and Mytilidae abundance during the preoperational period (n=123; p=0.013 for non-colonials and p=0.018 for Mytilidae), and no significant differences after 1990 (n=59; p=0.428 for non-colonials and p=0.446 for Mytilidae).
5 l
1 l* Periodic enhancement of mytilid abundance has been documented near effluents of other power plants in New England, but these changes were short-lived (several months), with no long-term effect on long-term benthic community structure (BECO 1995; NUSCO 1996). While these analyses indicate possible increases in Mytilidae and total abundance in the nearfield area during the operational period, time-series of annual means for these parameters for nearfield and farfield stations exidbited remarkably similar patterns (Fig. 3). For both parameters, it appears that the operational period increase at the nearfield station was largely the result of a single year of exceptionally high abundance (1993). Given the documented spatial and temporal variability in abundance pattems exhibited by Mytilidae in these studies and elsewhere (Menge 1976; Seed 1976; Fell and Balsamo 1985; King et al.1985; Newell et al.1991; Petraitis 1991; Seed and Suchanek 1992) and the overall dominance of this taxon on surface panels, the changes noted during the operational period are not consistent with a power plant impact. ,
Mytilidae abundance and total faunal density were also monitored on the nearest natural hard 1 l
surfaces as part of the marine macrobenthos destructive sampling studies. These studies revealed 1
no changes in Mytilidae abundance or total faunal density on submerged rock ledges during Seabrook operation for all four nearfield/farfield pairs, including the B19/B31 pair near surface 1
panel study sites (NAI 1996b). Another component of the marine macrobenthos program, the l subtidal bottom panels program, monitored settlement of benthic organisms, including Mytilidae, l on artificial substrata placed near natural hard surfaces. Results of this study indicated increases in Mytilidae abundance during the operational period at both the nearfield (B19) and farfield l
(B31) stations, which is not consistent with a power plant impact. Similarly, macrozooplankton l
studies showed an overall increase in Mytilidae plantigrade larvae during the operational period 6
!* in both nearfield and farfield areas.
Annual development of the fouling community was assessed through analyses of monthly sequential and quanerly sequential panel data. Seasonal abundance pattems of selected taxa on monthly sequential panels were similar between preoperational and operational years. Statistical analysis of community indices (Table 1) indicated a difference between stations in preoperational-operational periods trends in one instance (no. of taxa); however, this result (i.e., an increase during the operational period at the nearfield station, with no difference at the farfield station),
taken in context with the between-period similarity of most other study parameters, does not represent a change of developing fouling community beyond what is expected from natural variability. Results of the quarterly sequential panel study in 1995 were consistent with monthly sequential panel results, and through panel replication, provided information on within-station variability. For most parameters analyzed (biomass, abundance of selected taxa), variability within a collection was quite high, particularly during peak periods (NAI 1996a). Similar l
variability has been documented in other exposure panel studies (e.g., Brown and Moore 1977).
The 15 Teredo spp. individuals found in quarterly and monthly sequential wooden surface !
panels in 1995 was not an unexpected event for the Seabrook area. Occasional specimens have been collected previously during the surface panels study, including 1976 and 1979 at Station j
B19, and 1980 at Station B31 (NAl 1977,1981a, b). Additionally, Teredo spp. veliger larvae have been observed in bivalve larvae samples every year since 1984.
Occurrence of Teredo navalis, the most common teredinid north of Cape Cod, has been well 4
documented in the Gulf of Maine (Grave 1928; Tumer 1966; Gosner 1971; Culliney 1975), at l
times exhibiting periodic outbreaks (Dow and Baird 1953). Based on the historic documentation 7
P of Teredo in Gulf of Maine through these and other studies, and the fact that Teredo sp. was ,
identified at both nearfield and farfield stations in 1995, the most recent occurrence in 1995 surface panels cannot be attributed to the operation of Seabrook Station. Similarly, overall results i
of surface panel, marine macrobenthos and hydrothermal studies show no indication that Seabrook Station operation has impacted the local fouling community.
C Conclusions f e
i L
Twenty years of surface panel studies (including five full years (1991-1995) of Seabrook l operation) have demonstrated that the two original objectives of this program have been met. .
The temporal settlement patterns of potential foulers of power plant structures have been
]
characterized, and none have created plant operational problems. Current biofouling control measures and the in-station fouling panels program have proven to be sufficient to maintain plant operability.
The extensive physical and fouling community database gathered since 1975 has provided all I
needed evidence for effective impact assessment. Environmental conditions in the vicinity of
- Seabrook Station discharge before and after plant operation have allowed a balanced indigenous 4
. fouling community to colonize and develop on nearby hard surfaces, with no evidence of power !
plant effects. Specifically, hydrothermal studies (Padmanabhan and Hecker 1991) have shown )
that the nearfield surface panel study area is more exposed to the thermal plume than the nearest i
, natural hard substrate habitats (Outer Sunk Rocks). These studies indicate that there is no natural j i
l 4
- 8 i
l* hard benthos or fouling community affected by the thermal plume. Consistent with this physical data,20 years of biological studies of both areas (surface panels and marine macroben'hos study sites) indicate no evidence of ecological impacts to hard benthos from Seabrook operation. In addition, the same community parameters, dominant taxa, and patterns of settlement and development studied on surface panels are also monitored by the marine macrobenthos program on the nearest natural hard surfaces (destructive and non-destructive studies) and on subtidal l bottom panels (Table 2) in the vicinity of stations B19 and B31 (Fig.1).
Based on this evaluation, we request to discontinue all surface panel monitoring because no impacts have occurred after five years of Seabrook Station operation.
l l
l References Cited I
BECO (Boston Edison Company). 1981. Benthic studies in the vicinity of Pilgrim Station. I Section III.B. in Marine ecological studies related to operation of Pilgrim Station. Semi-Annual l
Report No.18. January 1981-June 1981. l
- Brown, R.T., and S.F. Moore. 1977. An analysis of exposure panel data collected at Millstone Point, Connecticut. MIT, Cambridge, Massachusetts. Rep. No. MIT-EL 77-015. I19 pp.
Cairns, J. (ed.). 1982. Artificial Substrates. Ann Arbor Science Pub., Inc. Ann Arbor, Michigan. 279 pp. '
Cory, R.L.., and J.W. Nauman. 1969. Epifauna and thermal additions in the Upper Patuxent River Estuary. Chesapeake Sci. 10:210-217.
Culliney, J.L. 1975. Comparative larval development of the shipworm Bankia gouldii and Teredo navalis. Mar. Biol. 29:245-251.
l l
Dow, R.L., and F.T. Baird, Jr. 1953. Methods to reduce borer damage to lobster traps. Tech.
Bull. No. 3. Dept. of Sea and Shore Fisheries. Augusta, Maine. 15 pp.
9 l
. . . .. - .. -_ .- . - ~. .
4 J C Fell, P.E., and A.M. Balsamo. 1985. Recruitment of Afytilus edulis L. in the Thames estuary, l
- with evidence for differences in the time of maximal settling along the Connecticut shore. ;
- Estuaries 8
- 68-75.
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~ . , _ _ m _ .. . _ _ _ . _ _ _ . _ _ _ _ _ . . _ . _ _ . . _ _ _ . . _ . _ _ . . _ . _ _ _ _ .
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' l characterization of environmental conditions in the Hampton-Seabrook area during the operation l
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characterization of environmental conditions in the Hampton Seabrook area during the operation of Seabrook Station. Prepared for North Atlantic Energy Service Corp.
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i 1
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= surface panels Fig.1. Surface panel sampling stations. From NAl (1996a) 13
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l o se i.coe :.aco SCALE IN FEET l Fig. 2. Locations of selected Seabrook Station thermal plume isotherms (17,27, and 37) under various tidal conditions in relation to the nearfield surface panel station (B19), based on hydrothermal modelling and field verification studies. From Padmanabhan and Hecker (1991).
14
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i Fig. 2. (continued)
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Pi
!' Total Abundance am - me
- am soo l:
/ :
soo l \
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Fig. 3. Annual geometric means of total abundance and abundance of Mytilidae on short-term panels at Stations B19 and B31,1978-1984 and 1987-1995.
1 I 16 i
?
1 Table 1.
Summary of evaluation of discharge plume effects on the fouling community in the vicinity of Seabrook Station. From NAl (1996a).
1 NEARFIELD- 1 FARFIELD OPERATIONAL DIFFERENCES PERIOD SIMILAR TO CONSISTENT WITH COMMUNITY PARAMETER' PREVIOUS YEARS PREVIOUS YEARS?'
Fouling community: Abundance no NF:Op> Preop Settlement' FF;Op= Preop No. of taxa yes yes Biomass yes yes l
Fouling community: Biomass yes yes Development' Fouling community: Abundance yes yes Development-year end' No. of taxa no NF;Op> Preop l FF;Op= Preop Biomass yes yes Fouling community: Mytilidae yes NF:Op> Preop Settlement' FF:Op= Preop Jassa marmorata yes yes Tubularia sp. yes yes
- Abundance, number of taxa, biomass, total density, and frequency of occurrence evaluated using ANOVA or t-test. !
- NF = nearfield, FF = farfield. '
' Settlement = short-term panels; development = monthly sequential panels; year-end = one year exposure period.
l 0
17
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- j. !
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- Table 2. ,
A summary of community parameters and selected taxa assessed in surface panel and marine r macrobenthos studies as described in NA! (1996a, b).
l ser1bre Panels Marine Macrohenehee ,
Short-term Monthly Quarterly Bonom panels Intertidal Subtidal Sequential j
Sampling stauons Bi9.B31 i B19.B31 B04.B19. BIMLW. B5MLW B04. Bl3. Bl7 i B31.B34 B19.B31.B34.
l _, B35 Community
[ paramesen
{i Species richness monthly time-senes assessed monthly /
if and ANOVA quarterly t-tests, for assessed with ANOVA for Aug.
assessed with ANOVA for Aug. '
1-yr panels Total abundance monthly time-series assessed monthly / assessed with assessed with (fauna only) - and ANOVA quarterly, t-tests for i- ANOVA for Aug. ANOVA for Aug.
, 1 yr panels I 1
(
Total biomass monthly tune serws assessed monthly / assessed for algae assessed for algae and ANOVA questerly. ANOVA triennual samples, triannual samples.
on monthly panels. ANOVA for Aug. ANOVA for Aug. ,
t-tests for 1-yr '
panels j Selseced taxa l Mytilidas monthly tinw senes monthly / quarterly
' dominant taxon. dominant taxon. domment taxon.
and ANOVA time series ('6 counts on triennual triannual aburut tnannual abund.
freq.) and hfe.
and annual panels estunates and life estimates.
l history studies stage studies ANOVA. and life stage studies Jana marmorara monthly time series monthly / quarterly dominant taxon and ANOVA time-series (% (shallow subtidal freq.) and hfe-sites). tnamiual history studws abund. estimates.
ANOVA and life stage studies '
Tubulana sp. monthly tune-series monthly < quarterly counts on annual presence absence presence.: absence 9 and ANOVA time-series (% panels for August for August J freq-)
l Lammano sp. assessed on 1 yr counts on annual inannual abund.
q, panels with t testa panels estimates and ANOVA in transect studv.
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