The mean particle size of GN sediments increased throughout the year and 

 the silt-clay content decreased. Since the GN station is not effected by 

 plant operation these changes are considered natural and the continuation 

 of a trend that began during 1980. The mean particle size of IN sediments 

 remained consistent over the year, but the silt-clay content increased 

 substantially in June. This increase in silt-clay was caused by erosion of 

 soils used in construction of the Unit 3 intake, and not by the operation 

 of Units 1 and 2. 



Changes in the subtidal communities involved the addition of Polydora 

 caulleryi among the dominant species at three of the four stations, (GN, 

 JC, EF) , and the increased density of Exogone hebes at all stations, 

 particularly IN, The increased abundances of P^. caulleryi at Millstone 

 subtidal stations was considered a natural and sediment associated change 

 since the non- impacted (GN) and potentially- impacted stations (JC, EF) 

 showed elevated densities during the same sampling period. Further, Kinner 

 and Maurer (1978) noted high densities of P^. caulleryi in medium to coarse 

 sediments within Delaware Bay. Sediments of this type are common at JC, EF 

 and GN, while the IN station is generally comprised of fine sediments. 

 Additionally, heavy siltation in June at IN may have buried newly settled 

 P^. caulleryi . 



While the density of Exogone hebes increased at all stations in 1983, 

 the high abundance at IN may have also resulted from changes in the 

 sedimentary environment. Gibbs (1969) reported high densities of E^. hebes 

 in the silty layers of fine to very fine sediments in Plymouth Sound, 

 England. The addition of silt to the already fine IN sediments could have 

 enhanced niche availability, while the active burrowing nature of E. hebes 

 would prevent burial caused by siltation. 



CONCLUSIONS 



During 1983, the spatial differences observed among infaunal sampling 

 stations and the temporal variations in abundance and species numbers were 

 typical of those observed in previous years. Natural, physical processes 

 appeared most responsible for the different spatial distribution of species 

 and temporal variations exhibited by the communities located within and 

 beyond the influence of the power plant. Changes in community structure 



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