The movement of fishes and invertebrates between ecosystems can be a major source of energy to marine food webs. We use stable isotope analysis to trace and quantify these subsidies. In the northeastern Gulf of Mexico we determined that pinfish migration accounts for ~25% of the energy available to offshore food webs.
Large gag grouper (Mycteroperca microlepis) in the Gulf of Mexico, like the one above and left, receive a significant portion of their energy via the migration of small fishes from nearshore habitats such as seagrasses. These subsidies are important for supporting many fisheries species and can allow for offshore food webs to support far more biomass than reef food webs may be able to support in isolation.