A-25 



Hudson Canyon was a large white galatheid crab Munidopsis 

 rostrata which was seen only on hard substrates. 



Community Analysis and Depth Zonation 



The results of the principal components analysis yielded 

 some broad faunal trends that could be related to depth and 

 substrate variability. However, extreme care must be taken 

 in interpretation of this data. The obvious problem with this 

 sort of survey is that samples tend to be concentrated in 

 areas that were not randomly chosen, hence this raises the 

 question of how representative they are of the study area as a 

 whole. This factor is compounded by the problem of species 

 recognition from photographs. Thus, patterns seen may or may 

 not be real in terms of species distribution if two closely 

 related species could not be discerned on the basis of gross 

 morphology. 



The data was first run with all dominant taxa included 

 in the data matrix. This analysis resulted in 73% of the 

 variation in the entire sample set being explained by 10 

 species or species assemblages. The first four end-members 

 of the analysis were monospecific, meaning that the numeri- 

 cally dominant species tended to be independently distributed. 

 In a biological sense this basically means that these species 

 are being controlled by different variables, and do not form a 

 tight interactive assemblage of organisms. The pattern that 

 does emerge is one of gradual replacement of species over 

 depth intervals. 



