Ecologists seek to understand the ways that human activities are altering the structures and processes that support biodiversity and nature's contributions to people. Food web research at the interface of community and ecosystem ecology is promising in this regard. An industry of studies has utilized stable isotopes in recent decades to rapidly characterize energy and material transfer among organisms in freshwater food webs. Nevertheless, these efforts have been somewhat siloed and mainly locally-based, and lack of a centralized database has limited efforts to tackle questions about food web change using isotopes at a global scale. Here we present IsoFresh, a freshwater food web database that contains species-level carbon (δ13C) and nitrogen (δ15N) stable isotope values for 15343 organisms, representing 1001 food webs and including > 1600 fish species and associated potential prey, from 65 countries around the globe. Our hope is that IsoFresh is used to explore fundamental and applied food web questions, contributing new knowledge about global environmental change so that human societies can better conserve and manage freshwater ecosystems along desirable future trajectories.
