Wednesday, June 6, 2007 - 1:45 PM
278

Quantifying Great Lakes Wetland Habitat Structure for Environmental Assessment

Lucinda Johnson1, Jennifer Olker1, Valerie Brady1, Jan J.H. Ciborowski2, and Dan Breneman2. (1) Natural Resources Research Institute, University of Minnesota, Duluth, MN 55811, (2) Department of Biological Sciences, University of Windsor, Windsor, ON NiB 3P4, Canada

Great Lakes shorelines are degraded by hydrologic modification (watershed/wetland drainage & dyking), poor water quality (sediment, nutrient & contaminant inputs), and biological consequences of invasive organisms. Yet, the stressors’ influence on physical structure of shoreline habitats is poorly understood. We surveyed physical/biological structure of 5 geomorphic classes of Great Lake margins at >140 locations varying in anthropogenic pressure to determine the dominant structuring variables at  local and landscape scales, and the relative influence of local vs, watershed scale features on habitat quantity & quality. 66 aquatic and riparian habitat variables sampled across entire sampling units (wetland, bay, high energy shoreline), macrobenthic sampling transects and fish fyke net locations were summarized by principal components analysis (PCA). Four independent classes of variables related to 1) aquatic habitat types; 2) water column & substrate characteristics; 3) shoreline composition & vegetation and adjacent land use; 4) disturbance. Emergent vegetation and shallow-water substrate attributes were most affected by both geomorphic type and degree of stress, especially agricultural influences. We recommend several easily measured variables as simple surrogates for composite (PCA) measures of habitat structure.