J. Great Lakes Res. 31 (Supplement 1):171–187 Internat. Assoc. Great Lakes Res., 2005 Fish Habitat Use Within and Across Wetland Classes in Coastal Wetlands of the Five Great Lakes: Development of a Fish-based Index of Biotic Integrity

ABSTRACT. The relative importance of Great Lake, ecoregion, wetland type, and plant zonation in structuring fish community composition was determined for 61 Great Lakes coastal wetlands sampled in 2002. These wetlands, from all five Great Lakes, spanned nine ecoregions and four wetland types (open lacustrine, protected lacustrine, barrier-beach, and drowned river mouth). Fish were sampled with fyke nets, and physical and chemical parameters were determined for inundated plant zones in each wetland. Land use/cover was calculated for 1- and 20-km buffers from digitized imagery. Fish community compo-sition within and among wetlands was compared using correspondence analyses, detrended correspon-dence analyses, and non-metric multidimensional scaling. Within-site plant zonation was the single most important variable structuring fish communities regardless of lake, ecoregion, or wetland type. Fish com-munity composition correlated with chemical/physical and land use/cover variables. Fish community composition shifted with nutrients and adjacent agriculture within vegetation zone. Fish community composition was ordinated from Scirpus, Eleocharis, and Zizania, to Nuphar/Nymphaea, and Pontede-ria/Sagittaria/Peltandra to Spargainium to Typha. Once the underlying driver in fish community composi-tion was determined to be plant zonation, data were stratified by vegetation type and an IBI was devel-oped for coastal wetlands of the entire Great Lakes basin