In addition to seasonal changes, annual differences in infaunal 

 densities and species numbers have occurred at all intertidal monitoring 

 stations. Again, these changes were more evident at JC. Since 1976, 

 unusual periods of low population densities (in the case of JC, low 

 community densities) occurred between September 1977-September 1978 and 

 September 1980-September 1981. In many cases, reduced abundance has been 

 evidenced by the lack of a September peak, the period when many of the 

 dominant intertidal species were most abundant. This has been particularly 

 true at JC . Since intertidal communities are so strongly influenced by 

 seasonal environmental conditions, an increase (or decrease) in the 

 intensity of the naturally rigorous winter conditions, could lead to 

 regional changes in these assemblages which should be evident at all 

 stations. However, due to the difference in station orientation, this 

 influence was more apparent at the JC station. 



During 1983, the abundances, number of species, and species 

 composition were consistent with the long-term patterns established by 

 previous years studies. No long-term changes in any community parameter 

 have occurred solely at impacted stations. 



SUBTIDAL 



Spatial differences among potentially impacted vs non-impacted stations 



During 1983, the potentially impacted IN community was spatially most 

 distinct from all other subtidal communities. This assemblage contained 

 fewer species, and individuals and included more suspension feeders than 

 any other community. Although this station is located near the power plant 

 intake structures, previous hydrographic studies (NUSCo 1978) and 

 observations by divers indicate that natural tidal currents in this area 

 exceed those created during power plant operation. During 1983, however, 

 there were physical differences in the IN sediments collected in June most 

 likely as the result of wave induced erosion of soils being used during 

 construction of the Unit 3 intake. Sedimentation of this fine material in 

 the vicinity of the IN station lead to a considerable increase in the 

 silt/clay fraction of the sediments. However, the June infaunal sampling 

 was performed just after construction began and most likely, before the 



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