NO. 2 OLGA HARTMAN : SUBMARINE CANYONS 5 



partly on direct diving operations and partly on dredging and photo- 

 graphic records. A long list of species includes fishes and invertebrate 

 animals, chiefly those to be expected in shelf depths. Three kinds of 

 plants were noted : Zostera above the rim on the south side, elkhorn 

 kelp as isolated plants, and Macrocystis, another kelp, attached to large 

 cobbles. The most conspicuous animals inhabiting the sandy bottoms 

 were large burrowing clams and a ceriantharid anemone. Rocky out- 

 crops supported attached purple gorgonians and vermetid gastropods; 

 other surface dwelling forms included starfish, sea cucumbers, large 

 snails and a few purple sea urchins. On two occasions the egg capsules 

 of a squid, Loligo opalescens, were so abundant on the canyon rim 

 that they looked like snowdrifts. Of further significance was the ob- 

 servation of decaying vegetation of kelp and surf grass along the 

 canyon floor at its head ; this becomes filled with sand and detritus 

 carried by longshore currents. Submarine slides, estimated to occur 

 about once a year, caused deepening of the canyon up to 10 to 20 feet, 

 and was followed by subsequent filling with detritus. 



The invertebrate animals named in this report are chiefly shelf 

 species attached to hard substrata, or existing in sandy or shaley or 

 rocky bottoms. The study did not extend into the deeper parts of 

 either La Jolla or Scripps canyons, but noted that the associations of 

 animals possibly extended beyond the limits studied (see Results, be- 

 low). 



The physical aspects of canyons, their stability or occasional 

 change, and the remarkable uniformity may be partly due to the 

 existing biota, especially since it has been found that like sediments 

 support similar organisms within a canyon, in a range of depth, but 

 that they may differ from those in adjacent shelf, or slope or basin 

 depths, and in other canyons. 



Another current study on California canyons is that by Peckham 

 and McLean (1961, p. 43), concerned with the fauna of the head of 

 the rock-walled Carmel submarine canyon, in depths to 200 feet, using 

 diving technics. These authors reported on a transition in the fauna at 

 depths of 70 to 100 feet, chiefly characterized by the replacement of 

 plants for attached corals, sponges, bryozoans and other epifaunal 

 organisms. 



ACKNOWLEDGEMENTS 

 This project was supported by the Allan Hancock Foundation of 

 the University of Southern California and the National Science Foun- 



