148 



Life 



:^t'^ 



Figure 130. Abundant black 

 abalones Haliotis cracherodii 

 Leach in lower intertidal area 

 of southwest San Nicolas Is- 

 land. Photograph by R. M. 

 Norris. 



isopod Limnoria spp., the amphipod Chelura 

 terebrans, and the moUusk Teredo diegensis, 

 each of which can bore the wood so thor- 

 oughly that pihngs break and piers may fall 

 down (Hill and Kofoid, 1927; Menzies, 

 1951; Barnard, 1955). 



Many examples of Pleistocene faunas 

 from rocky shores are known on raised 

 marine terraces of southern California. A 

 good one is exhibited in a 2-meter section 

 of the twelfth terrace of the Palos Verdes 

 Hills now at an elevation of 1215 feet (371 

 meters) above sea level. Collections and 

 identifications by Woodring, Bramlette, and 

 Kew (1946, p. 94) show the presence of a 

 fauna that is characteristic of the full height 

 of the intertidal belt and includes Acmaea, 

 Haliotis, Tegula, Crepidula, Pamaulax (simi- 

 lar to Astraea), and many others famihar to 

 biologists who have studied the present 

 intertidal zone of rocky shores. Foraminifera 

 in the deposit have been identified by O. L. 

 Bandy (personal communication) as typical 

 of warm shallow water and of pre- Wisconsin 

 age. 



Pelagic Environment 



General 



The pelagic environment consists of sev- 

 eral zones separated according to depth of 



water. Over the continental shelf it is 

 termed the neritic zone and over deep 

 water from the surface down to perhaps 

 100 meters it is the epipelagic zone. For 

 southern California there may be little need 

 for separate use of these two terms because 

 their organisms are similar, owing to the 

 uniformity of the waters which is produced 

 by the small amount of runoff from the land 

 except during infrequent storms. Some dif- 

 ferences in pelagic organisms exist in the 

 two areas because of interrelationships with 

 benthos on the shelf (the sublittoral) zone, 

 but present information indicates that these 

 differences are minor, except for fishes. In 

 both the neritic and epipelagic zones plank- 

 ton (floaters and drifters) are far more 

 abundant than nekton (swimmers), and 

 phytoplankton far exceed zooplankton. In 

 the deeper zones, mesopelagic and bathy- 

 pelagic, the ratio of plankton to nekton is 

 probably smaller, and of course neither zone 

 contains much phytoplankton except in the 

 form of debris raining down from the 

 epipelagic zone above. The deepest zone of 

 the ocean, the abyssopelagic, is absent in the 

 continental borderland. 



Epipelagic Zone 



Phytoplankton is restricted to the epi- 

 pelagic zone and the adjoining neritic zone 



