The Future of Waterfowl Habitats in the Canadian Lower Great Lakes Wetlands

Waterfowl utilization of wetlands along the Canadian shore of the lower Great Lakes, and the impact of eutrophication, metal pollution, organic pollution, and sedimentation on both the wetlands and the birds are reviewed. The following stages of eutrophication have been identified in the region: increased biomass of filamentous algae, increased submerged macrophyte biomass, increased planktonic algal biomass followed by loss of submergent weedbeds, loss of floating-leaved plants and annual emergents, increased areas of cattail marsh followed by decline, bare mud substrates with anoxic sediments resulting in botulism-related mortality of birds. Comparison with a European model suggests that eutrophication, pollution, and sediment loads act synergis-tically to cause deterioration of these habitats. Restoration will require not only the control of point sources of pollution, but also a change in farming practices such as drainage and intensive crop production which, through runoff, are major contributors to sediment loads and eutrophication.