A Fish-Eye View of Connectivity Across Watersheds and Effects on Downstream Waters

Whereas it is generally appreciated that fish can move extensively through stream networks, our understanding of key spatial processes that drive population dynamics is surprisingly limited. Here I provide a basic overview of some of these processes, including metapopulation dynamics, habitat complementation, supplementation, and neighborhood effects. I then turn to summarize what we know about importance of these processes for stream-living fishes and how they are relevant for understanding connectivity. From these examples I show that a spatially-explicit approach to studying fish in networks often leads to a fundamentally different view of the processes that are important for driving their productivity and persistence. This, in turn, has important implications for how we measure, model, and map physical processes in stream networks, and for how we implement management to protect and restore fish habitat. In conclusion, I argue there is compelling evidence that a perspective grounded in an understanding of spatial ecological processes should lead to a much better understanding of how both physical and biotic processes interact in stream networks. This perspective also provides a natural framework for better bio-physical integration in river research and management.