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THE INFLUENCE OF FOREST FRAGMENTATION AND OTHER ENVIRONMENTAL FACTORS ON LAKE SUPERIOR STREAM FISH ASSEMBLAGES
Citation:
Brazner, J. C., D K. Tanner, V M. Snarski, S L. Batterman, N E. Detenbeck, AND K. Olsen. THE INFLUENCE OF FOREST FRAGMENTATION AND OTHER ENVIRONMENTAL FACTORS ON LAKE SUPERIOR STREAM FISH ASSEMBLAGES. Presented at 1999 Midwest Fish and Wildlife Conference, Chicago, IL, December 5-8, 1999.
Description:
As part of a comparative watershed project investigation land cover/land use disturbance gradients for streams in the western Lake Superior region, we wanted to determine the relative influence of hydrogeomorphic region, forest fragmentation, watershed storage and in-stream habitat on fish assemblage structure and function. GIS characterization of 362 second and 90 third order watersheds for size, mature forest cover, area recently logged, and total wetland area allowed us to select 48 second and third order watershed from two hydrogeomorphic regions to examine fish assemblage response to landscape treatment factors. During the summers of 1997 and 1998, electrofishing gear was used to sample fish from stream reaches along fragmentation and watershed storage gradients in each region. Numerous floodplin, riparian and in-stream habitat variables were measured at 13 transects within each reach following fish sampling. Although a variety of region, fragmentation and storage related factors had significant influences on fish assemblages, water temperature appeared to be the single most important factor. We found lower temperatures and trout-sculpin assemblages at lower fragmentation sites, and higher temperatures and minnow-sucker-darter assemblages as storage increased. Factors related to riparian shading and flow distinguished brook trout streams (shaded/lower flow) from brown/rainbow trout streams (less shaded/higher flow).