Development and use of fish-based indicators of wetland quality for Great Lakes coastal wetlands

Seilheimer, T. S.
Ph.D. Thesis for the Department of Biology, McMaster University


This study focuses on fish habitat in Great Lakes coastal wetlands and the impact of environmental degradation, from nutrient and sediment loading, on fish assemblages. Wetland fish communities were studied on multiple spatial scales from a detailed study of a single wetland to one hundred wetlands over the entire Great Lakes basin. This research will be useful for wetland management by providing baseline information on fish habitat in coastal wetlands over a wide gradient of environmental conditions. This study details the development of the Wetland Fish Index on a group of forty-one wetlands in the southern and eastern Great Lakes, and the subsequent modification of the Wetland Fish Index to include sixty-one fish species found in northern and western Great Lakes. The Wetland Fish Index provides managers with a rapid method for assessing wetlands and tracking wetland condition through time. Analyses of water quality, fish community, and fish-based indicators show that conditions in an urban wetland, Frenchman’s Bay, have been relatively stable since the early 1980s. Differences in fish community and water quality were also shown between the northern sampling site, which is more degraded from watershed inputs, and the southern sampling site, which had more degradation-intolerant fish species. Changes in the wetland condition in both fish community structure and fish-based indicators were shown for Lake Ontario wetlands since the implementation of Remedial Action Plans. Finally, three biotic indices for measuring wetland condition were compared and their relative strengths and weaknesses were assessed. The zooplankton-based index was not successful in ranking wetlands with minimal degradation, while both the aquatic macrophyte-based and fish-based indices performed equally well for measuring wetland condition. The use of biotic indicators in Great Lakes wetlands are powerful tools for managers and researchers and are an essential aid in the protection of wetland habitat.

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