JC and GN was accompanied by increases in more traditionally dominant members of these communities 

 (e.g., Lumbrineris tenuis, Aricidea catherinae, Polycirrus eximius) 



Temporal shifts in community composition and abundance have occurred throughout the study at 

 all subtidal stations. This variation often reflects the interaction of biotic and abiotic factors (CouU 

 1985; Holland 1985; Nichols 1985) and temporal shifts in numbers of species, abundance, diversity and 

 species composition are characteristic of shallow-water benthic communities (Green 1969; Eagle 1975; 

 McCall 1977; Watling 1975; Holland and Mountford 1977; Rachor and Gerlach 1978; Loi and Wilson 

 1979). Even though subtidal abundances in the 1986, were lower than in recent years, regression models, 

 which included natural abiotic factors as variables, accounted for the lower values; thus the observed 

 differences were not due to plant operation. Shifts in infaunal species abundance probably reflected 

 variations in recruitment success and mortality, processes which are frequently linked to predation and 

 changes in the local physical and chemical environments (Nichols 1985; Gallagher et al. 1983). The 

 short-term rearrangements in the ranking of a few of the dominant species apparently reflect the effect 

 of these natural phenomena (Watling 1975; Flint and Younk 198.3; Nichols and Thompson 1985). 



SUBTIDAL CONCLUSIONS 



The Millstone subtidal benthic monitoring program detected some power plant related impacts at 

 stations in the immediate vicinity of the discharge (EE) and intake (IN) structures. Observed changes 

 occurred prior to 1985, and were attributed to Unit 3 construction activities and not to operation of 

 Millstone Units 1 and 2. Recent observation of community parameters at IN indicate the area is 

 recovering from the disturbance. The opening of the second discharge cut may have caused recent 

 changes in sedimentary and community parameters observed at EE. The widespread nature of infaunal 

 community changes at GN and JC suggest a response to naturally occurring events and are not related 

 to operation or construction of the Millstone facility. Data obtained during this study period will enable 

 us to distinguish any future impacts due to 3-unit operation of the Millstone facility from those that 

 occur naturally. 



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