28 



ALLAN HANCOCK PACIFIC EXPEDITIONS 



VOL. 27 



SAN DIEGO TROUGH, NORTHERN END 



This filled-in basin has some of the characteristics of a trench be- 

 cause its bottom areas contain living animals. It is included here be- 

 cause it was not evaluated in the basin report (Hartman and Barnard, 

 1960). Six samples, from 343 to 423 meters, yielded animals at all 

 depths. Biomasses are low, ranging from 3.7 to 0.5 grams per sample. 

 Most animal species occur as single individuals, but some are grouped, 

 notably Myriochelej a polychaete, best represented at 420 to 422 meters, 

 and Amphiura seminuda, an ophiuroid, in 420 meters. Most of the 

 species are those found in shallow to deep parts of the long-shore 

 canyons. 



LA JOLLA CANYON 



Eleven samples (see Fig. 10) come from 79 to 976 meters; sample 

 sizes range from 0.26 to 5.74 cuft and all were taken with the 

 Campbell grab. Biomasses range from negligible, coming from the 

 largest or third deepest sample, up to 81.8 grams from a moderately 

 large sample in 121 meters. Largest individuals in shallow, 79 to 121 

 m, depths are CerebratuluSj a nemertean, Aphrodita, Asychis and 

 other polychaetes. In deeper, 545 and 637 m depths, the largest are 

 Brissopsis and Arhynchite. 



-T 



Aricid?A. rdJ-nosAj: 



s; 



iliceous Sponge 7'y'T"*'*' 



LA JOLLA CANYON 



17° 70 



Contour Intervals in Meters 

 Numbers indicaite depth in feet. 



Showing; major communities of animals, 

 from shallowest to deepest axes depths. 



Fig. 10. La Jolla canyon, with contour intervals in meters. Numbers 

 indicate depth in feet. The major communities of organisms 

 are shown, from shallowest to deepest axes depths. 



