103 



3 in terms of species-group affiliations but differs in constancy and/or 

 fidelity levels of species-groups B, C, D and G. Species-groups H, J 

 and K are most characteristic of site-group 8, as they are present in 

 medium to high constancy and with high fidelity. Site-group 9 consists 

 of one station which is qualitatively different from all other stations 

 in several regards. 



Species-group N is unique in that it occurs at all the site-groups 

 and is present in high to very high constancy at six of the nine 

 site-groups. Naturally, with such widespread constancy its fidelity to 

 individual site-groups is very low. Examination of the frequency of 

 occurrence of the member species of species-group N shows that they 

 occur at from 53.6 to 87.5% of the stations sampled. This explains the 

 distinct separation of species-group N from the others in the dendrogram 

 (Fig. 37). Excepting the special cases of site-groups 6 and 9, we can 

 characterize the fauna of Casco Bay by species-group N. This group of 

 very tolerant, numerically dominant species which are undoubtedly 

 typical of nearshore bottoms over a large area. Superimposed on this 

 homogeneous fauna are smaller groups of species which are responding to 

 finer environmental distinctions and hence have a more restricted range 

 within Casco Bay. It is from among these other groups that initial 

 changes in community structure, potentially indicative of enviromental 

 degradation, should be sought. 



Several physical and biological parameters are compared in Table 11 

 on a site-group basis. The observed differences were subjected to 

 standard analysis of variance and the site-groups differed significantly 

 (> 95%) from one another in each of the measured parameters. This is 

 strong evidence that the numerical classification, using only species 



