A-51. 



CONCLUSIONS 



On the whole the analysis of the submersible photographs 

 identified submarine canyons as providing rather unique habi- 

 tats for their faunal constituents. They provide a variety 

 of substrate types, and are implicated as being areas of 

 increased current activity and nutrient enrichment. Our 

 analysis supports the evidence that suggests the existence of 

 three major faunal provinces on the continental margin. The 

 shelf and shelf-break area is dominated by crustaceans and 

 fish. While fish dominate the upper portion of the slope and 

 echinoderms dominate the lower slope. This trend was somewhat 

 obscured within canyons, attesting to the greater environmental 

 heterogeneity afforded by canyons. The canyon fauna is unique 

 in that it is frequently composed of high percentages of 

 sessile organisms such as corals and sponges. At intermediate 

 depths filter-feeding corals tend to dominate the faunal assem- 

 blage. Another finding was that canyon epifauna was generally 

 more abundant than slope epifauna at comparable depths. 



Within these three major depth zones gradual faunal 

 replacement with increasing depth was observed. Shallow water 

 species tended to have narrower depth ranges than deep water 

 species. These ranges may be determined by the availability 

 of suitable substrates rather than by temperature variability 

 or barometric pressure. Another trend noted was that of the 

 gradual emergence of some species with increasing latitude. 



