Biological accomodation in the deep-sea benthos: comparative evidence on the importance of predation and productivity

Measures of the diversity and relative abundance of gastropod predators are positively and significantly correlated with overall gastropod diversity in 15 epibenthic sled samples collected from 478 to 4862 m along the Gay Head-Bermuda transect. Predator diversity is lowest on the abyssal plain, highest on the lower continental slope and abyssal rise, and relatively low on the upper continental slope. The variation of gastropod predator diversity with depth is similar to those of their most probable prey, the polychaetes and protobranch bivalves. Predator diversity and overall diversity were also related to variation in faunal density with depth. Density decreases exponentially with depth and reflects the average rate of production reaching the deep-sea benthos. Relationships among diversity, predation, and production are consistent with the theory that predators exert a diversifying influence on communities and that the degree to which they are able to do this depends on the rate and stability of production. The results suggest that both predation and productivity are important to biological accomodation in deep-sea communities and that their relative contributions to maintaining diversity vary considerably with depth.