Science Inventory

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Description:

We analyzed data from coastal wetlands across all five Laurentian Great Lakes to identify patterns in fish assemblages and relationships to local habitat, watershed condition, and regional setting. NMDS ordination of electrofishing catch-per-effort data revealed an overriding geographic and anthropogenic stressor gradient that was strongly related to water clarity, vegetation structure, and fish composition. Wetlands in Lake Erie and lower Lake Michigan with agricultural watersheds, turbid water, little submerged vegetation, and a preponderance of generalist, tolerant fishes occupied one end of this gradient while wetlands in Lake Superior with largely natural watersheds, clear water, abundant submerged vegetation, and diverse fish communities occupied the other. Fish composition was also related to wetland morphology, hydrology, exposure, and substrate, but this was only evident when examining the less-disturbed wetlands. Anthropogenic disturbance appears to homogenize fish composition among coastal wetlands and mask other fish - habitat associations. Because land use is strongly spatially patterned across the Great Lakes and because aquatic vegetation is a key habitat element that responds to both biogeography and disturbance, it is difficult to disentangle natural from anthropogenic drivers of fish composition.

Purpose/Objective:

The objectives are to use assemblage ordination techniques to examine Great Lakes coastal wetland fish patterns on a basin-wide scale, and to relate them to geographic setting, anthropogenic impacts, and wetland habitat.

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