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A Multi-Assemblage Index of Stream Integrity: What Are the Fish, Bugs and Algae Telling Us?
Brian H. Hill 1, Frank H. McCormick 2, Michael B. Griffith 3, Alan T. Herlihy 4,
Philip R. Kaufmann 5, John L Stoddard 5 and Robert M. Hughes 6
1 US Environmental Protection Agency, Duluth, Minnesota
2 US Forest Service, Olympia Forestry Sciences Laboratory, Olympia, Washington
3 US Environmental Protection Agency, Cincinnati, Ohio
4 Department of Fisheries and Wildlife, Oregon State University, c/o USEPA, Corvallis, Oregon
5 US Environmental Protection Agency, Corvallis, Oregon
6 Dynamac, Inc., c/o USEPA, Corvallis, Oregon
We compared fish, macroinvertebrate, and periphyton assemblages collected from 400 streams with stream chemistry, channel and riparian habitat conditions, and watershed land use to develop an integrative, multiple assemblage index of biotic integrity. Streams were sampled from 1993-1998 as part of the US Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) surveys of the Mid-Atlantic region. We correlated 60 fish, 100 macroinvertebrate, and 200 periphyton assemblage attributes, and fish, macroinvertebrate, and periphyton indices of biotic integrity, with the environmental variables. On the strengths of their correlations with individual environmental variables and with the environmental gradients described by canonical axes, 9 attributes (3 fish, 3 macroinvertebrate, 3 diatom) were selected for a multi-assemblage index of biotic integrity (MABI). The 3 single-assemblage indices and the MABI were then compared on the strengths of their correlations with the individual environmental stressors and the with the disturbance gradients described by the canonical axes. In general, each assemblage's attributes and indices responded differentially to the environmental variables and disturbance gradients, but were similar in their overall assessment of regional-scale stream conditions. The MABI attempts to capture the unique stressor-response signals of each assemblage into a single index while retaining the fidelity of the regional assessment.
Keywords: diatoms, EMAP, fish, index of biotic integrity, macroinvertebrates, regional surveys