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DETECTING LEVELS OF SUSTAINABLE LAND-USE IN LAKE SUPERIOR WATERSHEDS USING STREAM INVERTEBRATE COMMUNITIES
Citation:
Brady, V. J., N E. Detenbeck, S L. Batterman, J. C. Brazner, V M. Snarski, AND D L. Taylor. DETECTING LEVELS OF SUSTAINABLE LAND-USE IN LAKE SUPERIOR WATERSHEDS USING STREAM INVERTEBRATE COMMUNITIES. Presented at 3rd North American Forest Ecology Workshop, Duluth, MN, June 24-27, 2001.
Description:
We have been investigating the relationship between watershed land-use and stream ecosystem "health" within 48 western Lake Superior watersheds, trying to identify sustainable land-use levels. Aquatic invertebrates, often useful in evaluating stream condition, were collected from riffles in each stream. Nonmetric multidimensional scaling (NMDS) ordination was used to evaluate invertebrate community differences and to correlate those differences with landscape, habitat, water chemistry, sediment, and hydrology variables. NMDS of the invertebrate communities indicated that vertebrates in both north and south shore streams were responding primarily to substrate, hydrology, and temperature differences among the diverse stream types. Ordinations on streams grouped by major common features were evaluated to better detect possible anthropogenic influences. Invertebrates in 21 north shore streams seemed to be most influenced by stream bottom type, temperature, stream and watershed size, and flow. Direct effects of human activity on stream communities were not apparent. However, land use may be altering sedimentation rates, hydrologic regimes, and stream temperature, and, thus, may be indirectly affecting stream invertebrates.