56 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 27 



Highest values are generally the result of the presence of one or a 

 few large individuals, these sometimes weighing more than all others 

 combined. Some such animals are thalassemid echiuroids, echinoid echi- 

 noderms, large holothurians, or large shelled gastropods. 



Lowest values exist in the mouth ends of the canyons along shore, 

 where they join basins. These values range from 2.0 to 20.3 grams 

 to a square meter (Hartman and Barnard, 1958, p. 4) and highest 

 values occur in the outer series of basins, with the highest in Long 

 basin, where a value of 49.7 grams to a square meter was largely 

 due to the presence of an echiuroid worm. 



ABUNDANCE OF ANIMALS RESPECTING AREAL 



COVERAGE 



Total numbers of species and specimens follow a fairly uniform 

 pattern and generally decrease with depth. Infrequent occurrences of 

 very low or very high numbers can be correlated with unusual factors. 

 Thus, the summarized low values in Monterey canyon can be at- 

 tributed to sparse sampling and the low values in San Clemente rift 

 valley are the result of ineffective penetration by the grab. Other low 

 figures may be noted in Hueneme canyon, in 98 meters, where only 

 13 species and 30 specimens of polychaetes contrast with much higher 

 numbers in all other depths. This bottom is possibly a disturbed one. 

 The same applies to the one from 271 meters, where only 6 species 

 and 9 specimens are recorded. In Mugu canyon a poor bottom was 

 encountered in 119 meters where only 6 species and 15 specimens were 

 taken ; here the presence of Capitella suggested a polluted or diluted 

 substratum. In Dume canyon at 299 meters, only 14 species and 20 

 specimens of polychaetes were tabulated ; the sample contained three 

 large specimens of Brisaster townsendi, weighing 153.7 grams; it is 

 possible they were predatory on the fauna in their immediate environs. 



An unusually high count in Santa Monica canyon, in 116 meters, 

 was due to the presence of Capitella capitata subspp., perhaps related 

 to the proximity of outfall lines discharging fresh water. Redondo 

 canyon showed high counts in nearly all samples. Its lowest values 

 occurred on the fan, where impoverished conditions prevail. Unusually 

 high values were encountered in 741 meters, where 309 individuals, 

 nearly all small ampharetid polychaetes, were counted. 



In La Jolla canyon, at 274 and 371 meters, the samples were high 

 in specimens of Capitella. This canyon was somewhat impoverished 



