Citation:

Kelly, V. J. AND D H. Landers. LARGE-SCALE PATTERNS OF STREAMFLOW DISTURBANCE AND FISH COMMUNITIES IN UPPER MISSOURI RIVER BASIN, USA. Presented at 5th International Symposium on Ecohydraulics, Madrid, Spain, September 12-17, 2004.

Description:

Patterns of streamflow variability are likely to be a major organizing feature of the habitat template for stream fishes. Functional organization of stream communities has been linked to streamflow, especially to patterns of flow variability that describe the physical disturbance regime in stream fishes. The disturbance regime in streams is frequently represented by the variability in streamflow from both floods and prolonged low-flow periods. Streamflow disturbance is generally measured by the intensity, frequency, and predictability of timing for these extreme streamflow patterns. These kinds of ecologically-relevant streamflow metrics provide important context for understanding the response of fish assemblages to physical habitat conditions. This response is usefully described by functional as well as taxonomic characterization of fish assemblage composition, in order to provide greater inference about underlying physical processes. In particular, understanding the functional responses of fishes to the streamflow regime is critical for effective water resource management and stream restoration in areas of high levels of human water use.

This study evaluates the utility of metrics derived from flood- and low-flow frequency distributions to describe the functional characteristics of fish assemblages in Dakota streams of the upper Missouri Basin, USA. This region is characterized by extreme seasonal patterns of temperature and precipitation, and extensive water use for irrigation. Data are provided from the USEPA's Environmental Monitoring and Assessment Program (EMAP), a probability-based survey that is developing approaches to characterize habitat and biological status of rivers in 12 western states. Additional data are provided from the streamflow and water-use databases of the U.S. Geological Survey, and water-permit and dam inventory databases from the State water resource agencies. Flood- and low-flow frequency distributions are determined for EMAP sites from regional streamflow analysis of USGS gages. Because of the extent of human water use in this region, inference for ungaged sites is provided by regionalization of watershed characteristics that include a suite of human influences such as water permits and dam inventories. Functional organization of the fish assemblages is described by morphological and life-history attributes. The analysis of streamflow patterns and fish assemblage structure is focused on identification of distinct stream and community types, and determination of the association between patterns of habitat and community variation with streamflow factors. An emphasis is given on distinguishing local from regional controls on the diversity of physical habitat features and fish community attributes.

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