In 1982, numerical classification techniques could be applied to a 

 long term (3 yrs) data base for the first time (NUSCo 1982). Classifica- 

 tion of intertidal and subtidal communities (stations) illustrated high 

 within-site community similarity (Figs. 3 and 4); the relationship among 

 and between-sites provides strong comparative data against which future 

 changes in overall community structure will be evaluated. Additionally, 

 classification of species that numerically dominated over three years 

 has revealed recurrent groups of species characteristic of the infaunal 

 communities around Millstone Point (e.g. taxa in Group I in Figs. 5 and 

 6). Further long term information on specific populations will enhance 

 our ability to detect more subtle impacts which might otherwise be 

 impossible to detect at the community level. 



Other quantitative measures used to describe infaunal communities 

 have also become more appropriate, given the longer data base now available. 

 Over three years, seasonal patterns in community density (Fig. 7) and 

 numbers of species (Fig. 8) that were previously masked by within-year 

 variability, have become recognizable. 



The benthic program is now providirig 16ng term data that is directly 

 comparable to previous years. The overall result is that we are now 

 able to characterize these communities in terms of the "consistency" and 

 relative "stability" over years rather than in terms of the "variability" 

 observed within any single year. 



Since much of the data collected prior to 1979 and nearly all 

 collected prior to 1976 (when samples were frozen) do not provide long 

 term continuity, we believe that our current program should be continued 

 through the Unit 3 operational phase. This study will provide the long 

 term data base needed to quantitatively assess any changes in infaunal 

 density or composition caused by the addition of Unit 3. 



16 



