NO. 2 OLGA HARTMAN : SUBMARINE CANYONS 



SUBMARINE CANYONS OF SOUTHERN CALIFORNIA 



PART II 

 BIOLOGY 



By Olga Hartman 



INTRODUCTION 



This study of the benthic fauna of the submarine canyons off 

 southern Cah'fornia is the third in a series of areal studies on the 

 quantitative, ecological, and systematic evaluations of the marine ben- 

 thic invertebrate animals existing along the borderlands of southern 

 California. A biological sampling program was begun in 1952, along 

 the shelf and slope lands of the San Pedro area, using a large 

 orange-peel-grab sampler, covering about a fourth of a square meter 

 of surface. The analysis of more than two hundred samples from the 

 San Pedro area resulted in the recovery of several hundred kinds of 

 invertebrate animals, with locations showing their distribution, abun- 

 dance, community structure and physical environment (Hartman, 1955). 

 The shallow bottoms of Santa Monica Bay were next sampled, chiefly 

 in the environs of outfall lines, from shallowest shelf to slope depths. 

 The results (H,artman, 1956) showed the possible effects of waste 

 products on the kinds, numbers and productivity of bottom areas. 

 Analyses of 150 samples revealed the predominance of polychaetes in 

 shallowest depths, followed by polychaetes with small crustaceans and 

 pelecypods in deeper bottoms. A more diversified fauna but lower in 

 standing crop was found in areas more remote from waste bottoms. 



The shelf depths off southern California, from Point Conception 

 to. south of the Mexican border, were next sampled. Several thousand 

 quantitative samples were taken between 1955 and 1960. The analyzed 

 results, based on more than 200 samples completely classified, revealed 

 the presence of many kinds of animals existing in predictable as- 

 sociations and changing with kinds of sediments, distance from shore, 

 depth of bottom, and other physical factors. The detailed analyses 

 (Hartman, in press) are voluminous; they provide data on more than 

 1700 species of invertebrate animals, including chiefly polychaetes, 

 echinoderms, small crustaceans (mainly amphipods), mollusks (mainly 

 small pelecypods), echiuroids, and a few other kinds. 



