Dietary guild structure of the fish community in the Northeast United States continental shelf ecosystem

Abstract

Trophic guild analysis identifies groups of species that use similar resources within a community. We evaluated the trophic guild structure in an assemblage of 40 fish species in the North- east United States shelf ecosystem using a 25 yr database of food habits. We explicitly accounted for ontogenetic diet shifts by separating predator species into size classes. There were 14 significant trophic guilds. These distinguished predators based upon prey size and location in the water column (i.e., benthic to pelagic feeding). Ontogenetic diet shifts were important in guild structure, particu- larly within dominant piscivores. The mean dietary overlap both between and within guilds was notably lower than in other fish communities due to the broad spatial and temporal scale of the study, the diversity of prey types consumed, and the generalist nature of predators in this system. The guild concept is a useful framework to simplify highly connected, complex ecosystems like the Northeast US continental shelf and identify ecologically similar functional units.