Macroinvertebrate community composition relative to chemical/physical variables, land use and cover, and vegetation types within a Lake Michigan drowned river mouth wetland

Abstract

We analyzed macroinvertebrate community composition from 19 sites, spanning 5 vegetation types, in the White River drowned river mouth wetland (eastern shore of Lake Michigan). Sites were distributed along a gradient of anthropogenic disturbance from the less-impacted upper wetland to the more-impacted lower wetland. The relative importance of surrounding land use and cover, water quality, and vegetation type in structuring macroinvertebrate communities was evaluated using correspondence analysis (CA) of biotic data, and principle components analysis (PCA) of chemical/physical water quality data. A significant correlation (p = 0.001) between site scores of the CA and PCA showed that ambient chemical/physical water quality was likely an important driver of macroinvertebrate community composition. Canonical correspondence analysis (CCA) was then used to corroborate this relationship. Vegetation type, did not appear to structure macroinvertebrate communities to a significant degree. Both water quality and macroinvertebrate community composition correlated with surrounding land use and cover. Therefore, we hypothesize that macroinvertebrate communities in the White River drowned river mouth wetland respond to surrounding land uses via its influence on the abiotic environment. This response occurred even at the within-system scale used in this study. Practitioners of bioassessment protocols should, therefore, be aware of spatial heterogeneity in both water quality and macroinvertebrate community composition in Great Lakes drowned river mouth wetlands.