NO. 2 OLGA HARTMAN : SUBMARINE CANYONS 49 



In 793 meters, with 2.7 grams: 



polychaetes 74.1% 



mollusks 25.9 



In 976 meters, with 1 1.4 grams: 



polychaetes 74.6% 



pogonophorans 14.9 



ophiuroids 10.5 



In 708 meters weights were negligible and the bottom impoverished. 



Coronado canyon: — This was sampled in depths of 123 to 1265 

 meters ; biomass values are as follows: 



211.4 gm/ sq.m., in 960 m. 30.8 gm/ sq.m., in 123 m. 



109.0 gm/ sq.m., in 566 m. 23.6 gm/ sq.m., in 1265 m. 



45.8 gm/ sq.m., in 344 m. 7.6 gm/ sq.m., in 812 m. 



42.2 gm/ sq.m., in 1 77 m. 4.8 gm/ sq.m., in 1 105 m. 



Most significant in this canyon is the fact that highest values are 

 in considerable depths (960 m), that the shallowest end has low values, 

 associated with the presence of Capitella, and that values increase 

 thereafter due to the presence of a diversified shelf fauna. The bottoms 

 are impoverished at about 812 meters, and below this level a deepwater 

 fauna exists. These three dips are best seen at the 177 m, 812 m and 

 1105 m levels, and the peaks of standing crops at 566 m, 960 m and 

 1265 m levels. 



Percentages of weights by major animal groups are as follows: 

 In 123 meters, with 15.4 grams: 



ophiuroids 68.2% 



polychaetes 29.9 



crustaceans 1-9 



In 177 meters, with 21.1 grams: 



polychaetes 68.7% 

 mollusks 9.5 



ophiuroids 9.0 



an echinoid 3.8 



In 344 meters, with 22.9 grams: 



polychaetes 52.4% 



2 echinoids 42.8 

 a nemertean 4.8 



