Local control of recruitment in an epifaunal community and the consequences to colonization processes

Abstract

We found that recruitment, abundance, and dominance within two subtidal epifaunal communities in southern New England, USA persist year after year over large areas of the bottom. This long-term persistence in both dominance and recruitment is not expected in such an open system with disturbances continually creating open patches for recruiting larvae whose identity and abundances change both temporally and spatially. We suggest that the persistence results from strong local control of recruitment that overrides any variability in larval production and dispersal of species from outside a site. Although local dynamics that control persistence involve all life-stages, we found that intense predation on post-settlement individuals has drastic effects. This predation alters the relative abundances of recruits, prevents the invasion of some species, and allows others to dominate. In addition, epifaunal communities are often dominated by species producing short-lived, poorly dispersed larvae. The continued local recruitment of these species at a given site can contribute to the long-term persistence of dominants already present. Based on these observations, we suggest that a system of locally reproducing, self-sustaining populations coupled with strong local environmental differences (e.g. predation on recruits) limiting the invasion of other species may better represent some subtidal benthic communities than a system with widely-dispersed larvae, recruitment dominated by production outside the community, disturbance creating continual changes in dominance, and little long-term persistence.