A-3 



occurs where the sandy sediment of the shelf is replaced by 

 the silty sediment of the upper slope. The lower faunal 

 boundary occurs near the start of the lower slope which is 

 steeper, has a lower sedimentation rate and offers a greater 

 degree of substrate variability than does the upper slope. 

 However, the authors do point out that while the zones and 

 boundaries are indicative of the fauna as a whole, indivi- 

 dual species may have depth ranges that extend into at least 

 two of the zones. They also noted that the shallow and 

 middle faunal assemblages are dominated by various species 

 of fish, while the deeper zone is dominated by echinoderms. 



Rowe and Menzies (]969) and Rowe (1971) studied the 

 epibenthic fauna of Hatteras Canyon and the adjacent slope 

 using a combination of trawls and bottom photographs. Rowe 

 found that some of the dominant species of the continental 

 slope are present in reduced abundances, or are altogether 

 absent, in the canyon axis. This phenomena may be the 

 result of habitat differences between the canyons and the 

 adjacent continental slope. The canyons are characterized 

 by a higher variability of substrate types, such as outcrop, 

 and this provides a more heterogeneous environment. Addi- 

 tionally, canyons differ from slope regions in that they may 

 be areas of nutrient enrichment due to the reported funneling 

 characteristics of canyons (Rowe, 1972). 



Haedrich, Rowe, and Polloni (1975) conducted their 

 study of epibenthos using trawls. They found that the 



