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DETECTING STREAM INVERTEBRATE COMMUNITY ALTERATION DUE TO MID TO LOW LEVELS OF WATERSHED LANDSCAPE MODIFICATION
Citation:
Brady, V. J., N E. Detenbeck, S L. Batterman, J. C. Brazner, V M. Snarski, AND D L. Taylor. DETECTING STREAM INVERTEBRATE COMMUNITY ALTERATION DUE TO MID TO LOW LEVELS OF WATERSHED LANDSCAPE MODIFICATION. Presented at North American Benthological Society Meeting, LaCrosse, WI, June 3-9, 2001.
Description:
As part of an investigation into the effects of watershed landscape alteration on stream ecosystems, quantitative invertebrate samples were collected from riffles in 26 second and third order south shore Lake Superior streams. Nonmetric multidimensional scaling (NMDS) ordination was used to evaluate invertebrate community differences and to correlate those differences with landscape and habitat (riparian zone, instream habitat, water chemistry, sediment and hydrology) variables. NMDS of the vertebrate communities separated these Lake Superior streams into three distinct groups. Invertebrates were affected by major differences in sediment and hydrology among streams. Ordinations on streams grouped by common substrate features were evaluated as a means to better detect possible anthroprgenic influences. Although there was little difference among sandy streams (9 streams) and clay streams (11 streams) each yielded solutions that recovered 92% and 77% of the variation in their invertebrate datasets. Invertebrates in both rocky and clay stream groups appeared to be responding to differences among stream substrate and 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.