Dietary connections of marine species in Puget Sound Marine Ecology Progress Series

Ecosystem-based fisheries management requires an understanding of the interactions between managed and unmanaged species and the connections they have with their habitats. Although aquatic plants provide important shelter for a variety of species, an often-overlooked component is the extent to which primary producers contribute to the diet of upper trophic levels. In this study, we reconstructed the dietary connections among 13 consumers, including vulnerable rockfish species, to 3 basal sources: particulate organic material (POM), eelgrass, and macroalgae. Using stable isotope ratio data, macroalgae was estimated to represent the greatest contribution to the diets of 11 consumers, with an average percent dietary contribution of 59% across all consumers, relative to POM (24%) and eelgrass (15%). For young-of-the-year rockfish (Sebastes sp.), POM and eelgrass together comprise approximately 48% of their basal diet, yet these same sources contributed <25% to the basal diets for older juvenile copper and quillback rockfishes (S. caurinus and S. maliger, respectively). Understanding the strength of these trophic relationships is an important step for predicting ecosystem consequences following perturbations within these habitats, and such information is vital to managers making decisions related to the conservation of valuable populations.