Are Infaunal Predators Important in Structuring Marine Soft-Bottom Communities?

Abstract

The role of infaunal predators in structuring marine soft-bottom communities was evaluated according to these predators': 1) effects on prey density based on manipulative field experiments, 2) feeding rates, 3) effects on prey distribution, 4) effects on species diversity, and 5) interactions with their prey. Estimates of feeding rates indicate that many predatory taxa have the potential to reduce the size of prey populations and suggest that nemerteans are likely to have a larger impact on infaunal abundances than polychaetes. Infaunal predators have been demonstrated to have a significant effect on infaunal densities and to affect the spatial and temporal distribution of their prey. The effects of these predators on species diversity apparently depend on the predator and the diversity of the system. These conclusions may not be applicable to all soft-bottom habitats or all groups of infaunal predators because they are based on studies of very few taxa conducted almost exclusively in intertidal, unvegetated, mud habitats. Additional studies are needed on the effects of predation by infauna on infaunal population dynamics and on the mechanisms of interactions between predator and prey. Further investigation will probably reveal that different groups of infaunal predators play different roles in structuring soft-bottom communities.