Ecology of Western Lake Superior Region

Abstract

The twin ports of Superior, Wisconsin and Duluth, Minnesota were founded at the head of the world's greatest continuous mass of freshwater. The Laurentian Great Lakes contain about 20% of the world's freshwater resources. Half of that water is contained in the largest and most pristine of these lakes - Lake Superior. The tremendous size and purity 9f this water body make it one of the world's unique aquatic ecosystems. In addition to this resource, the Superior-Duluth harbor is protected by the largest natural inland sand bar in the world. Minnesota and Wisconsin Points, with a com­ bined length of over 9 miles, serve to protect what has become one of the largest and busiest ports in the world. The estuary itself contains over ll,500 acres of water and is fed by many small tributaries and two major river systems, the Nemadji and the St. Louis. The St. Louis River is the largest U.S. tributary to Lake Superior (See Figure 1). The juxtaposition of the estuary and Lake Superior and the effects of a major port on these water resources have served to create unique and contrasting aquatic environments. Some species populations in these two environments benefit and take advantage of both, while others are segregated by environmental gradients such as temperature or water purity. These in­ teractions, along with other physical conditions restricted to Southwestern Lake Superior, provide a variety of unique opportunities for the study and understanding of the behavior of freshwater organisms.