Benthic invertebrates that form habitat on deep banks off southern California, with special reference to deep sea coral

There is increasing interest in the potential impacts that fishing activities have on megafaunal benthic invertebrates occurring in continental shelf and slope ecosystems. We examined how the structure, size, and high-density aggregations of invertebrates provided structural relief for fishes in continental shelf and slope ecosystems off southern California. We made 112 dives in a submersible at 32−320 m water depth, surveying a variety of habitats from high-relief rock to f lat sand and mud. Using quantitative video transect methods, we made 12,360 observations of 15 structure-forming invertebrate taxa and 521,898 individuals. We estimated size and incidence of epizoic animals on 9105 sponges, black corals, and gorgonians. Size variation among structure-forming invertebrates was significant and 90% of the individuals were <0.5 m high. Less than 1% of the observations of organisms actually sheltering in or located on invertebrates involved fishes. From the analysis of spatial associations between fishes and large invertebrates, six of 108 fish species were found more often adjacent to invertebrate colonies than the number of fish predicted by the fish-density data from transects. This finding indicates that there may be spatial associations that do not necessarily include physical contact with the sponges and corals. However, the median distances between these six fish species and the invertebrates were not particularly small (1.0−5.5 m). Thus, it is likely that these fishes and invertebrates are present together in the same habitats but that there is not necessarily a functional relationship between these groups of organisms. Regardless of their associations with fishes, these invertebrates provide structure and diversity for continental shelf ecosystems off southern California and certainly deserve the attention of scientists undertaking future conservation efforts. Manuscript submitted 8 December 2004 to the Scientific Editor’s Office. Manuscript approved for publication 21 July 2005 by the Scientific Editor. Fish. Bull. 104:167–181 (2006). Benthic invertebrates that form habitat on deep banks off southern California, with special reference to deep sea coral Brian N. Tissot Program in Environmental Science and Reg 14204 NE Salmon Creek Ave. Washington State University Vancouver, Washinton 98686-9600 E-mail address: [email protected] Mary M. Yoklavich Fisheries Ecology Division Southwest Fisheries Science Center National Marine Fisheries Service, NOAA Santa Cruz Laboratory 110 Shaffer Road Santa Cruz, California 95060 Milton S. Love Marine Science Institute University of California Santa Barbara, California 93106 Keri York Program in Environmental Science and Reg 14204 NE Salmon Creek Ave. Washington State University Vancouver, Washington 98686-9600 Mark Amend Southwest Fisheries Science Center National Marine Fisheries Service, NOAA Santa Cruz Laboratory 110 Shaffer Road Santa Cruz, California 95060 ional Planning