Definition

General natural community overview

Lake Superior is a unique and vast resource of fresh water covering 31,700 square miles. It is the largest freshwater lake in the world by surface area and has 156 miles of coastline in Wisconsin. The lake is primarily cold water with summer maximum water temperatures below 22 degrees Celsius. Lake Superior is relatively infertile with a historic fish fauna that consisted primarily of lake trout, ciscoes/whitefishes (Salmonidae), and sculpins (Cottidae). Warmer and more fertile harbors and bays (e.g., Chequamegon) had a more diverse assemblage of cool and warmwater fishes, especially in the family Percidae. Now the biota is dominated by introduced or invasive non-native species. Due to extirpations in other lakes, Lake Superior supports the last remaining Great Lakes population of two whitefish relatives - kiyi and shortjaw cisco.

Lake Superior has not experienced the same levels of development, urbanization and pollution as the other Great Lakes. Although Lake Superior is the cleanest and most healthy of all the Great Lakes, it is still threatened by toxic pollutants that bioaccumulate in the food chain and persist in the environment. These substances can be transported long distances in the atmosphere and end up in the lake. Local sources contribute pollutants to air and water, adding to the pollutant load entering Lake Superior. Because of its long retention time (191 years), pollutants entering Lake Superior can remain in the lake for over a century before draining to the lower Great Lakes.

Rare animals

Species of Greatest Conservation Need

The following Species of Greatest Conservation Need are listed according to their level of association with the natural community type, based on the findings in the Wisconsin Wildlife Action Plan.

Please see the Wildlife Action Plan, Chapter 2.4 to learn how this information was developed.

Opportunities

Management Opportunities

The following Ecological Landscapes have the best opportunities to manage for , based on the Ecological Landscapes of Wisconsin Handbook.

Major
A major opportunity for sustaining the natural community in the Ecological Landscape exists, either because many significant occurrences of the natural community have been recorded in the landscape or major restoration activities are likely to be successful maintaining the community's composition, structure, and ecological function over a longer period of time.

Important
Although the natural community does not occur extensively or commonly in the Ecological Landscape, one to several occurrences do occur and are important in sustaining the community in the state. In some cases, important opportunities may exist because the natural community may be restricted to just one or a few Ecological Landscapes within the state and there may be a lack of opportunities elsewhere.

Present
The natural community occurs in the Ecological Landscape, but better management opportunities appear to exist in other parts of the state.

Threats / Actions

These threats and priority conservation actions were identified for the community type in Wisconsin, and they apply to all of Wisconsin's Ecological Landscapes unless otherwise indicated. Please see the Wisconsin Wildlife Action Plan, Chapter 3.3 , for more information

Threats

• Exotic aquatic plant and animal species alter aquatic habitats, food webs and species interactions.
• Development and urbanization of harbors and river mouths is causing degradation and loss of wetland and aquatic habitats.
• Contamination from industrial micro-contaminants (e.g., polychlorinated biphenyls or PCB’s) are making fish unsafe to eat.
• Dams on tributaries block fish migration.
• Non-point source pollution resulting from urbanization and poor watershed land-use practices is degrading nearshore and tributary habitat and water quality.
• Overfishing (now largely controlled and regulated) historically depressed some populations.

Conservation actions

• Various treaties, institutions, and citizen groups exist to help manage biodiversity in Lake Superior, and these resources should be called upon to assist with management for Species of Greatest Conservation Need.
• Improve regulations and education to prevent the introduction of additional exotic invasive aquatic species and the slow the spread of existing invasive species.
• Protect and restore harbor and river mouth habitats.
• Work to reduce or eliminate and remediate sources of micro-contaminants.
• Remove dams or install effective fish passages at dams.
• Improve watershed land-use practices to reduce non-point source pollution.
• Continue state involvement in federal and regional programs to minimize long-distance atmospheric transport of toxic and/or harmful substances.
• Continue application of effective fisheries management to ensure that commercial and recreational fisheries are maintained at sustainable levels.

Photos

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Photos

Note: photos are provided to illustrate various examples of natural community types. A single photograph cannot represent the range of variability inherent in a given community type. Some of these photos explicitly illustrate unusual and distinctive community variants. The community photo galleries are a work in progress that we will expand and improve in the future.