covers the JC beach throughout much of the year; this mat can significantly influence the numbers and 

 types of species found inhabiting intertidal beaches (Soulsby et al. 1982). 



Seasonal and year-to-year fluctuations in intertidal community abundance and composition were 

 evident throughout the Millstone sampling program. However, an extensive evaluation of seasonal trends 

 in species abundance are not appropriate because the sampling is performed only four times per year. 

 A more important consideration, from the monitoring standpoint, is the removal of natural, temporal 

 variation that can significantly reduce our ability to identify power plant related impacts on infaunal 

 communities. Intertidal communites are strongly influenced by physical environmental conditions 

 (Holland and Polgar 1976) and interannual variations in these conditions are expected to effect rather 

 large changes in the overall abundance and composition of these communities. Attempts to model this 

 variation at the community level, using abiotic factors as explanatory variables, removed 20-60% of the 

 total variation in community density and 60-63% of the variation in numbers of species observed since 

 1980. After adjusting for the effects of the variation in these factors, both the average numbers of 

 species and individuals have not significantly changed at any of our intertidal stations since 1980. Species 

 compositional changes have also been relatively minor at our intertidal stations, and over the baseline 

 period, were limited to rearrangements in the ranking of dominant species rather than additions or deletions. 



INTERTIDAL CONCLUSIONS 



Long-term studies of intertidal infaunal communites characterized areas communities within and 

 beyond areas that will be potentially impacted by the Millstone facility. These data established spatial 

 relationships among sampling stations, and investigated the extent and direction of temporal fluctuations 

 in the abundance and numbers of species that have occurred from 1980 - 1985. During this period, no 

 changes in intertidal communities could be attributed to operation of Millstone Units 1 and 2 or 

 construction of Unit 3. Data presented here appear representative of natural, undisturbed intertidal 

 communities and will be the basis for ail future impact studies performed during 3-unit operating conditions. 



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