Citation:

BRAMBLETT, R. G., T. R. JOHNSON, A. V. ZALE, AND D. T. HEGGEM. DEVELOPMENT AND EVALUATION OF A FISH ASSEMBLAGE INDEX OF BIOTIC INTEGRITY FOR NORTHWESTERN GREAT PLAINS STREAMS. TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY. American Fisheries Society, Bethesda, MD, 134:624-640, (2005).

Impact/Purpose:

There are four basic objectives of the project:

Demonstrate the application of a comparative landscape assessment in analyzing the vulnerability of surface and coastal water conditions to declines based on landscape conditions (as estimated by landscape indicators as demonstrated in the mid-Atlantic landscape atlas) in western environments;

Develop and apply landscape assessment approaches relative to specific issues, including an ability to prioritize the vulnerability of areas relative to the Clean Water Act 303(d) designations; Quantify relationships between landscape conditions (as measured by landscape indicators) and surface and coastal waters in the west to reduce the uncertainty in comparative landscape assessments, and issue-specific, landscape assessments (e.g., Total Maximum Daily Load (TMDLs);

Complete a west-wide, comparative landscape assessment relative to surface and coastal water vulnerability;

Transfer landscape assessment technologies to Regional Offices so that they can conduct landscape assessments at many scales.

Description:

Quantitative indicators of biological integrity are needed for streams in the Great Plains of North America, but it was not known if the Index of Biotic Integrity (IBI) approach would be effective in this semi-arid region. Great Plains streams have a depauperate and tolerant ichthyofauna and highly variable physicochemical conditions that may mask the effects of non-point source pollution and stream habitat degradation. We developed an IBI based on fish assemblages by screening metrics for range, responsiveness to human influence, precision, and lack of redundancy and tested the IBI's ability to detect anthropogenic effects by validating the index with an independent data set. The IBI was composed of 10 metrics based on species richness and composition, trophic and reproductive guilds, and age structure. These 10 metrics had many significant correlations with substrate and water chemistry variables but had fewer significant correlations with riparian condition and watershed variables. Of the watershed variables, road density had the highest number of significant correlations with 14 final IBI metrics. The IBI was validated by demonstrating its responsiveness to aggregate measures of human influence, site-level habitat, and water chemistry, and lack of responsiveness to factors that varied naturally, such as stream size and site elevation. The IBI was also temporally stable in repeat visits within and between years to a subset of sampled reaches. This IBI can be used as a measure of biological integrity for management of prairie streams faced with threats such as introduced species, intensive agriculture, grazing, and coalbed natural gas extraction. Although we developed this IBI based on data from Montana prairie streams only, our IBI can likely serve as a framework for other North American plains streams and our results suggest that the IBI approach may be useful in other semi-arid regions of the world.

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