XII. California borderland basins, 1,641 to 2,358 meters. 



The California outer borderland basins are found in depths normally 

 considered abyssal, but seem to have a fauna quite different from that of 

 equivalent depths to the south. Although this area (fig. 3) is not within 

 the strict area under consideration in this paper, it is important to indicate 

 these differences, and to list the fauna found there. The author was 

 fortunate to be consulted concerning fauna present in three areas along 

 the California coast from Los Angeles to San Francisco, as part of a study 

 of atomic waste disposal grounds, carried out by the Advanced Systems 

 Division of the Pneumodynamics Corporation. Nine 5-meter otter trawl 

 stations (Table III) were taken in depths of from 1641 to 2358 meters, 

 four in the Santa Cruz Basin off Los Angeles, three in the Farallon Basin 

 off San Francisco, and two in a small unnamed basin off Point Arguello. 

 Although the trav/ls used in the California borderland basins were smaller 

 than many of those used in the abyssal regions off Mexico, the inner liners 

 of the nets were of same mesh size. Catches were of comparable size, and 

 the individual animals were also of the same size in both regions. The 

 basic composition of catches from the two regions were also similar, i.e., 

 equal amounts of ophiuroids, asteroids, mollusks, polychaetes, etc. Tem- 

 peratures ranged from about 2.5° to 4°C., and oxygen about 1 to 1.5 ml/L., 

 while the sediments were all silty clay. 



None of the basins was completely closed, such as those described by 

 Hartman and Barnard (1958), and seemed to be well-oxygenated and 

 flushed by bottom currents. In configuration and environmental character- 

 istics these three areas differed little from the basins studied in the deep 

 borderland off Baja California, therefore it was somewhat surprising to 

 find such a completely different fauna there. All three areas were very 

 rich, both in species and in individuals. For instance, one short trawl 

 with a small 15 foot "try" net, produced two large tubs of living animals, 

 including hundreds of specimens of a small pecten, Cyclopecten randolphi 

 tillamookensis. One surprising aspect of this basin fauna was its close 

 affinity with bathyal and shelf fauna of the northern Pacific. Many of the 

 species were formerly known only from the Gulf of Alaska, and in the 

 vicinity of the Bering Sea and the Kamtchatka Peninsula. None of the 

 animals was typical of those collected by the Albatross in Central 

 American waters. This would suggest that there is some zoogeographic 

 separation in the deep sea, which parallels geographic breaks along the 

 shore. It also suggest that there is a migration south of many species 



