Fish communities in river networks provide significant ecosystem services that will likely decline under future land use and climate change. We developed a model that simulates the consequences to multiple populations of one or more fish species-a metacommunity- from multiple stressors across a river network. The model is spatiallyexplicit and age-structured, with three components: habitat suitability; population dynamics, including species interactions; and movement across a spatial network. Although this model is simple, it can form the basis of fisheries assessments and may be incorporated into an integrated modeling system for watershed management and prediction.

• Brenda Rashleigh(U.S. Environmental Protection Agency, Atlantic Ecology Division, Narragansett, Rhode Island, USA) Corresponding author
• Denis White(Oregon State University, Corvallis, Oregon, USA)
• Joe L. Ebersole(U.S. Environmental Protection Agency, Western Ecology Division, Corvallis, Oregon, USA)
• Craig Barber(U.S. Environmental Protection Agency, Ecosystems Research Division, Athens, Georgia, USA)
• George Boxall(U.S. Environmental Protection Agency, Western Ecology Division, Corvallis, Oregon, USA)
• Allen Brookes(U.S. Environmental Protection Agency, Western Ecology Division, Corvallis, Oregon, USA)