Ecological-Flow Response Relationships in the Ozark Highlands

Environmental flows are defined as the quantity, timing, and quality of stream flows required to maintain the function of particular organisms in a system or overall ecosystem structure and function. We developed ecological flow-response relationships in the Ozark Highlands, in conjunction with a new hydrologic classification of streams into natural flow regimes for this region. We sampled within the perennial groundwater flow regime at 21 USGS-gauged sites, stratifying by habitat type. We collected fish and crayfish using three-pass backpack electro-fishing, benthic macroinvertebrates qualitatively and quantitatively, and  habitat, geomorphological, and water quality data. We used hydrologic data to derive metrics based on magnitude, frequency, duration, and timing of flow, and calculated a hydrologic disturbance index (HDI) for all sites. In preliminary analysis of fish community data, we found significant negative relationships between Simpson's diversity and HDI and percent intolerant individuals and HDI, and a positive relationship between number of intolerant species and rapid habitat assessment score.  We also found a positive relationship between crayfish density and HDI. 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.