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Fact Sheet 2010–3110

National Water-Quality Assessment Program

Streamflow Characteristics and Benthic Invertebrate Assemblages in Streams Across the Western United States

By Anne M.D. Brasher, Chris P. Konrad, Jason T. May, C. Scott Edmiston, and Rebecca N. Close

Thumbnail of and link to report PDF (1.9 MB)Introduction

Hydrographic characteristics of streamflow, such as high-flow pulses, base flow (background discharge between floods), extreme low flows, and floods, significantly influence aquatic organisms. Streamflow can be described in terms of magnitude, timing, duration, frequency, and variation (hydrologic regime). These characteristics have broad effects on ecosystem productivity, habitat structure, and ultimately on resident fish, invertebrate, and algae communities. Increasing human use of limited water resources has modified hydrologic regimes worldwide. Identifying the most ecologically significant hydrographic characteristics would facilitate the development of water-management strategies.

Benthic invertebrates include insects, mollusks (snails and clams), worms, and crustaceans (shrimp) that live on the streambed. Invertebrates play an important role in the food web, consuming other invertebrates and algae and being consumed by fish and birds. Hydrologic alteration associated with land and water use can change the natural hydrologic regime and may affect benthic invertebrate assemblage composition and structure through changes in density of invertebrates or taxa richness (number of different species).

This study examined associations between the hydrologic regime and characteristics of benthic invertebrate assemblages across the western United States and developed tools to identify streamflow characteristics that are likely to affect benthic invertebrate assemblages.

For additional information contact:
Director, Utah Water Science Center
U.S. Geological Survey
2329 Orton Circle
Salt Lake City, Utah 84119

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Suggested citation:

Brasher, A.M.D., Konrad, C.P., May, J.T., Edmiston, C.S. and Close, R.N., 2010, Streamflow characteristics and benthic invertebrate assemblages in streams across the western United States: U.S. Geological Survey Fact Sheet 2010-3110, 4 p.



Study Design

Statistical Analyses


Summary and Conclusions

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