A-48 



Between the depths of 300 to 500 meters on the slope 

 south of Baltimore Canyon faunal similarity is extremely high 

 between adjacent 50-meter depth intervals (80% to 90%) . These 

 high values are due to the overwhelming presence of Hyalinoe- 

 oia artifex. This quill worm has a patchy distribution and 

 is extremely abundant where it occurs. It thus tends to 

 obliterate any trend found in the other fauna. Percentage 

 similarity, between adjacent 50-meter depth intervals, is 

 also uniformly high between 850 to 1300 meters (50%-80%) . 

 This high degree of overlap is due to the dominance of the 

 fish found throughout this zone. Percentage similarity is 

 again high between adjacent 50-meter depth intervals in the 

 1550 to 1800 meter range (70%-90%) . This is due to the 

 presence of one dominant species, Ophiomusium lymani 

 throughout this range. Faunal similarities between dives in 

 the depth range of 1700 to 1900 meters are also uniformly 

 high (70% to 80%) , being due to the ubiquitous presence of 

 Ophiomusium lymani. 



However, at intermediate depths comparisons between 

 slope and canyon fauna yield a low percentage faunal simi- 

 larity (10% to 20%) . The amount of species overlap between 

 adjacent depth intervals in a canyon is exceedingly variable 

 (3% to 90%). These results again point to the fact that 

 canyons provide rather unique habitats for their faunal 

 constituents. The high degree of environmental hetero- 

 geneity found on canyon walls provides opportunities for 



