CLEARWATERS: Ecosystem indicators for Lake Ontario

The Great Lakes Basin contains five lakes: Superior, Michigan, Huron, Erie, and Ontario. They span more than 750 mi from east to west along the U.S.-Canadian border. Together they comprise the earth's largest system of fresh surface water—more than 550 mi³ of water covering nearly 100,000 mi².

Excessive nutrients, toxic contaminants, exotic species, and habitat loss have taken their toll on the Great Lakes Ecosystem over the last two centuries. The magnitude of these effects became abundantly clear in the early 1970s when Lake Ontario colonial water birds experienced widespread and near total reproductive failures because of high levels of toxic contaminants in the fish they depend on for food.

Three decades later we find Great Lakes' water quality to be much improved, and the populations of Lake Ontario colonial water birds have recovered. The Lake Ontario Lakewide Management Plan (LaMP), a bi-national effort led by USEPA, Environment Canada (EC), NYSDEC, and the Ontario Ministry of the Environment (MOE); these are the “Four Parties” to LaMP.

LaMP provides a mechanism for coordinating continuing efforts to restore the Lake Ontario ecosystem. A recently completed set of ecosystem indicators furnishes one means for LaMP to track its progress in restoring Lake Ontario.

Backdrop

Lake Ontario is the last of the chain of Great Lakes that straddle the Canadian-U.S. border. Its shoreline is bordered on the north by Ontario and on the south by New York State.

Ontario is the smallest of the Great Lakes, with a surface area of 18,960 km² (7,340 mi²), but it has the highest ratio of watershed area to lake surface area. It is relatively deep, with an average depth of 86 m (283 ft) and a maximum depth of 244 m (802 ft), second only to Lake Superior. More than 80% of surface water inputs to Lake Ontario originate from upstream Great Lakes and connecting waters. Lake Ontario discharges to the St. Lawrence River.

Seven near-shore areas of Lake Ontario have been identified as “Areas of Concern.” They include Toronto Harbour and the Rochester Embayment, which bear significant adverse environmental effects related to localized contaminant sources. These problem areas are being dealt with through individual Remedial Action Plans (RAPs).

Developing ecosystem indicators

Much work has gone into developing Lake Ontario ecosystem objectives and indicators over the last decade. The earlier Lake Ontario Toxics Management Plan began the development of ecosystem goals and objectives when it formed the Lake Ontario Ecosystem Objectives Work Group (EOWG). U.S. and Canadian monitoring experts on the EOWG have developed broad ecosystem goals and objectives for Lake Ontario, and they were presented in the LaMP 1998 problem assessment report.

Trend during 1980-2001 in the number of established bald eagle nesting territories in the Lake Ontario Basin—one measure of ecosystem recovery.

Ecosystem goals for Lake Ontario
The Lake Ontario Ecosystem should be maintained and as necessary restored or enhanced to support self-reproducing diverse biological communities. The presence of contaminants shall not limit uses of fish, wildlife, and waters of the Lake Ontario basin by humans and shall not cause adverse health effects in plants and animals.

As a society we recognize our capacity to create great changes in the ecosystem, and we shall conduct our activities with responsible stewardship for the Lake Ontario Basin.

Ecosystem objectives
Aquatic communities: The lake waters shall support diverse and healthy reproducing and self-sustaining communities in dynamic equilibrium, with an emphasis on native species.

Wildlife: The perpetuation of a healthy, diverse, and self-sustaining wildlife community that utilizes the lake habitat and/or food shall be ensured by attaining and sustaining the waters, coastal wetlands, and upland habitats of the basin in sufficient quantity and quality.

Human health: The waters, plants and animals shall be free from contaminants and organisms resulting from human activities at levels that affect human health or aesthetic factors such as tainting odor and turbidity.

Habitat: Offshore and near-shore zones surrounding tributary, wetland, and upland habitats shall be of sufficient quality and quantity to support ecosystem objectives for the health, productivity, and distribution of plants and animals in and adjacent to the lake.

Stewardship: Human activities and decisions shall embrace environmental ethics and a commitment to responsible stewardship.

The LaMP took the next step and developed specific indicators with measures and targets needed to track progress in achieving its ecosystem objectives. Eleven indicators were selected using the following criteria. Indicators should:

Critical pollutant indicators: Concentrations of critical pollutants in water, young-of-the-year fish, herring gull eggs, and lake trout for comparison against existing guidelines

Lower food web indicators: Nutrients, zooplankton, and prey fish (for example, alewife and smelt), which reflect the ability of the ecosystem to support higher-level organisms such as lake trout and water birds

Upper food web indicators: Populations and reproduction rates of herring gull, lake trout, bald eagle, mink, and otter—all top-level predators dependent on quality habitat and sufficient populations of healthy prey, free of problematic contaminant levels.

These indicators reflect lakewide conditions and are sensitive to a number of stressors. For example, healthy populations of bald eagles and lake trout, both top-level native predators, indicate the presence of suitable habitat, healthy populations of prey organisms, and low levels of environmental contaminants. Healthy populations of eagles and trout also reflect society's commitment to responsible stewardship through actions to protect their habitats, limit their harvest, and reduce levels of contaminants in the environment.

Operating with the indicators

Now that indicators have been selected attention will shift to data collection and synthesis. Fortunately, much of this work is already being done through existing programs such as the binational Lake Ontario Committee of fishery managers. Further study will be necessary to define specific targets for phytoplankton, zooplankton, and prey fish populations, and it may require many more years before meaningful targets can be developed. Nevertheless, data collection and reporting on basic measures of these populations will—in the meantime—provide a measure of how well these aspects of the ecosystem are faring.
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Frederick Luckey is an environmental scientist with USEPA Region 2 and is currently assigned to NYSDEC in Albany as a Lakewide Management Planner. Phone 518-402-8133. Mr. Luckey wishes to hear comments or suggestions on the content of this article and the approach being taken to track progress in restoring the Lake Ontario ecosystem.