FISHERY BULLETIN: VOL. 72. NO. 2 



level of wind-influenced sediment distribution at 

 that season. 



6. Standing crop figures for the commercially 

 important clam, Mercenaria mercenaria, were 

 reduced in the bay as a whole. Some areas, 

 especially those in the path of the dredge, did 

 not recover one year after dredging. 



7. Land usage patterns were drastically altered 

 during the study as well as in the previous 15 yr. 

 Homes within 300 m of the bay increased by 94%. 



Rhodamine B placed in a toilet in a house 

 along the periphery of the bay was detected in 

 the bay water, although all houses have septic 

 tanks. Maximum coliform counts exceeded pres- 

 ent legal standards in 1968. 



8. Significant reductions in standing crop 

 figures occurred in the channel and the bay as a 

 whole. Recovery of biomass in the channel was 

 also affected by sediment composition and an 

 interaction between the sediment and the dredg- 

 ing process itself 



The effect of different sediment types and 

 seasonal variances on the biomass is shown to be 

 not significant, negating two of the most important 

 variables which might confuse the interpretation 

 of the pre-and post-dredging data. 



Chi-square analyses were done on number 

 of species and number of individuals in the bay 

 and in the channel. There were significant reduc- 

 tions in both parameters. Recovery of species and 

 specimen numbers appeared to be affected by 

 sediment type. 



Drastic reductions in biomass, species number, 

 and population size occurred in the dredged 

 channel as a function of the removal of the sub- 

 stratum and its in- and epifauna. Recovery had 

 not occurred at the termination of this study, 

 11 mo after dredging. 



Of perhaps greater significance are the sub- 

 stantial reductions in all parameters which oc- 

 cured in the bay as a whole, with only a few 

 stations showing recovery to pre-dredging levels. 

 Only one of the stations was more than 500 m 

 from the dredged channel and spoil deposition 

 areas. 



9. Goose Creek had a relatively high in- and 

 epifaunal standing crop estimated at 36.83 g/m^ 

 for the bay as a whole, including large forms. 

 This compares to Sanders' (1956) estimate of 

 54.627 g/m2 for Long Island Sound, but is much 

 higher than the standing crop levels obtained 

 for Upper Chesapeake Bay or the English 

 Channel. 



The number of organisms per m^ is lower for 

 Goose Creek than for the other areas reported 

 on, indicating a preponderance of large forms. 



10. Phytoplankton production in Goose Creek 

 was lower than that of Long Island Sound, but 

 far higher than that of the English Channel or 

 Upper Chesapeake Bay. There were three maxima 

 in phytoplankton production in Goose Creek in 

 1966-1967. 



11. The removal of the substratum in the 

 channel affected the population dynamics of the 

 infauna. The molluscs Tellina agilis, Lyonsia 

 hyalina, and Mulinia lateralis, while insignificant 

 components of the standing crop both before and 

 after dredging, increased in numbers in the post- 

 dredging samples. 



Two dominant forms, the polychaetes Cly- 

 menella torquata and Notomastus latericeus, 

 virtually disappeared after dredging. 



In the bay as a whole there appeared to be no 

 substantial change in the species mix, except 

 for the removal of the dense population of 

 Crepidula fornicata (34,000/m2) by the dredge 

 near the confluence of the three channels. No 

 recovery was noted for this species after 11 mo at 

 that station. 



In general, the bay sediments exhibited an over- 

 all reduction in epi- and infaunal populations, 

 which did not approach recovery levels 11 mo 

 after dredging. 



The Ampelisca spinipes and Nepthys incisa- 

 Nucula proxima communities described by 

 Stickney and Stringer (1957) and Sanders (1956, 

 1958) were not found in Goose Creek, being 

 replaced by a Clymenella torquata-Mya arenaria 

 community in the sandy sediments, and a Mer- 

 cenaria mercenaria-Sclerodactyla briaerius- 

 Nereis succinea community in the softer sub- 

 stratum. 



12. Animal productivity for Goose Creek was 

 calculated at 89.87 g/m^/yr before dredging and 

 31.18 g/m^/yr after dredging. During the post- 

 dredging year, 18,780 kg of animal production 

 was lost from the 0.32 km^ bottom of Goose Creek. 



13. The productivity of island II was considered 

 representative of unspoiled tall Spartina alterni- 

 flora marsh. Animal productivity was estimated 

 at 42.44 g/m^/yr, composed almost entirely of 

 Uca pugnax, Modiolus demissus, and Sesarma 

 reticulatum. This represented 5-7% of the total 

 productivity figures of 869.64 g/m^/yr. The gross 

 estimate for mixed peripheral marsh came to 

 4,553.57 kg/ha. Using this figure to calculate the 



476 



