Biota of the St. Marys River: habitat evaluation and environmental assessment

The St. Marys River provides vital habitat for many species of plants, invertebrates, fish, and birds. It is also subject to many at times conflicting uses, including recreational boating, sport and subsistence fishing, municipal and industrial withdrawals and inputs, as well as commercial ship traffic and hydroelectric power generation.In 1984, the United States and Canada jointly initiated the Upper Great Lakes Connecting Channels Study to identify and quantify the impacts of contaminants on these channels and their biota and to develop recommendations for more effective pollution control and surveillance programs. Results of the study in the St. Marys River showed that water entering the river from Lake Superior is of excellent quality. Industrial and municipal discharges in the Sault Ste. Marie, Ontario area have resulted in heavily contaminated sediments and a severely impaired benthic invertebrate community in this area and downstream; however, no major impacts on fish have been demonstrated. Nevertheless, major impacts of man on fish spawning and rearing habitats and on benthic and fish productivity have resulted from the alteration of channels, construction of navigation locks, and regulation of flow in the St. Marys Rapids. Increases in the productivity of such raptors as osprey during the 1980s suggest a reduction in organochlorine contaminants levels in their diet; however, the increasing numbers of gulls with low concentrations of PCBs, p,p-DDE and other organochlorines in their eggs may adversely affect gull young or their predators.