Influences of Flow Regime Alteration on the Abiotic and Biotic Components of Streams

Streams are altered by a variety of human-induced landscape changes (e.g., groundwater pumping, damming, and climate change). One of the most notable instream changes associated with these alterations is altered patterns of flow or the natural flow regime. Native fish species have adapted to the natural flow regime and rely on specific flow components (e.g., magnitude and duration of high flows during spawning) to successfully complete their life-history. The objective of this study was to develop and test several flow-ecology hypotheses for reproductive guilds of fishes to determine the relationship among abiotic components of streams and level of flow alteration. We assessed the structure of the current fish assemblage by sampling 15 streams of the Arbuckle Mountains and Ozark Highlands ecoregion. The abiotic structure (i.e., width-depth ratio, deposited sediment, channel unit heterogeneity, and residual-pool depth) of the 15 streams was measured and multivariate analyses were used to determine how flow regime alteration related to the physical structure of streams. The results of this study will be used to develop improved environmental-flow standards based on the needs of reproductive guilds and changes to the abiotic structure of streams.