The role of settlement in structuring a hard-substratum community in the deep sea

Abstract

Larval settlement can play an important role in the structure of benthic communities in shallow-water habitats. Experimental studies of settlement and colonization in the deep sea, however, are few, and have concentrated exclusively on sedimentary habitats. Results are presented here from an in situ study designed to determine whether larval settlement patterns on a common, deep-sea hard substratum (manganese nodules) determine the subsequent structure of the epifaunal community. In a 7-wk deployment at a depth of 1240 m, settlement onto manganese nodules resting on the sediment in a relatively “low-flow” environment was significantly greater than onto nodules suspended in a “higher-flow” regime. After 2 yr, this difference in total number of individuals was no longer significant, but a new pattern in community composition emerged, which correlated to the presumed supply of paniculate food. Suspension-feeders dominated the elevated nodules (correlating to higher horizontal participate fluxes) and deposit-feeders dominated the nodules sitting on the sediment (correlating to higher particulate deposition). The faunal settlement patterns observed after 7 wk, therefore, appear to be altered by adult feeding requirements of the component species.