Cooperative Fish and Wildlife Research Units Program: Vermont
Education, Research and Technical Assistance for Managing Our Natural Resources

Fish are known to use deep-sea coral and sponge (DSCS) species as habitat, but it is uncertain whether this relationship is facultative (circumstantial and not restricted to a particular function) or obligate (required for a species to persist). To address this uncertainty, we analyzed underwater video transects collected over a ten-year period, documenting the locations and abundance of DSCS and demersal fishes in the Southern California Bight. Non-metric multidimensional scaling, indicator species, and cluster analyses revealed six distinct DSCS assemblages based on depth and substratum, and we identified 44 fish taxa that were predominantly associated with a particular assemblage. We then used logistic regression to identify the ecological drivers most associated with the presence of individual fish taxa throughout the study area. Factors related to fish presence included depth, substratum relief, latitude, fish density, coral cover, coral height, and the abundance of individual coral and sponge taxa. Even after controlling for depth and substratum relief, multiple fish taxa were much more likely to be found in locations containing specific DSCS taxa. Of particular interest, young-of-the-year rockfishes (Sebastes spp.) were more than twice as likely to be found in locations with Placogorgia spp., suggesting that this gorgonian coral serves as nursery habitat. Our results provide valuable information on the relationships between environmental conditions and demersal community assemblages, which is necessary to understand how future oceanic conditions may influence the abundance and distribution of DSCS and associated fishes.