Flow-Ecology Relationships in the Ozark Highlands

Environmental flows are defined as the quantity, timing, and quality of stream flows required to maintain the function of organisms in a system or overall ecosystem structure and function. We developed ecological flow-response relationships in the Ozark Highlands based on a hydrologic classification of streams into natural flow regimes. We collected fish, crayfish, macroinvertebrates, habitat, geomorphological, and water quality data at 21 USGS-gauged sites in streams within the groundwater flow regime. We calculated hydrologic metrics based on magnitude, frequency, duration, timing and change rate of flow, and calculated a hydrologic disturbance index (HDI) for all sites. We found significant negative relationships between fish Simpson's diversity and HDI and percent intolerant individuals and HDI, and a significant positive relationship between number of intolerant species and rapid habitat assessment score.  We found the best model for predicting Simpson's diversity and percent intolerant individuals to be a single variable model consisting of total phosphorus.  This study can serve as the basis for more informed conservation of freshwater biota and ecosystems in the Ozark Highlands as well as providing methodologies for use in other regions.