Flow-Ecology Relationships of Fishes in the Ozark Highlands

We examined flow-ecology relationships in the Ozark Highlands over two years with contrasting environmental conditions, a drought year (2012) and a flood year (2013).  We examined metrics of community structure in fish using an IT multiple regression approach with a priori selected predictor variables incorporating hydrology, habitat, geomorphology, and water quality.  We found that hydrology was an important variable influencing fish community structure, but often less important than other types of environmental variables, especially in a drought year.  We found substantial between-year variation in flow-ecology relationships.  When a small set of a priori flow alteration metrics were examined we did not see strong flow alteration-ecology relationships.  Exploratory canonical ordination showed strong flow alteration-ecology relationships.  Fish responded to alteration in a combination of duration, frequency, and magnitude of flow variables.  Flow alteration, along with habitat, geomorphology and water quality, appear to have important influences on fish community structure.  Ecological responses that we observed differed significantly between drought and flood years, and this highlights the importance of understanding temporal variation in flow-ecology relationships for resource planning.  Variables and relationships highlighted by this study could be used by managers to conserve stream fish communities in the Ozark Highlands.