The need for relevant hydrologic data for studies of freshwater species distributions and diversity

Streamflow, water temperature, and sediment are primary factors influencing the survival, growth, and reproduction of aquatic species.  Directional alteration of these variables can impact local biodiversity and cause extirpation of populations.  Although accurate estimates of spatial variation in these variables are not available for many regions, these types of data are primary to predicting the response of species to human-induced changes in aquatic habitat.  Development of these environmental data through the use of appropriate physical models is critical to our understanding of the potential responses of watershed hydrology and aquatic biodiversity to projected changes in climate and land use.