The Great Lakes ecoregion contains 20% of the world's fresh surface waters. These enormous water bodies dominate the region's ecology, shaping its climate, landforms, hydrology, and biota. Although the Lakes and surrounding landscape have undergone major changes as a result of human activities, most of the system's special biodiversity still survives in scattered areas. The freshwater marshes and sand dunes of the Great Lakes shores are of special biological importance. Extensive coastal marshes and estuaries play a pivotal role in sustaining the Great Lakes aquatic ecosystem. They process nutrients and organic material from the land, and make a major contribution to the aquatic food web. Many of the lakes' fish species depend upon them for spawning and rearing, as do large populations of migratory waterfowl for feeding and staging areas. Coastal habitats such as sand dunes and alvars support a high proportion of unique species and communities.
The southern portion of this ecoregion is fragmented. In the northern areas of this ecoregion, incompatible resource development is a major threat. Summer cottage and resort development is a major threat along all the Great Lakes shorelines. In southern Ontario especially, almost all the habitat has been lost to suburban development and agriculture. Pollution is also a threat to this ecosystem, especially in large urban areas along the Great Lakes like Hamilton, Buffalo and Detroit-Windsor. Major waterways like the St. Clair River and the Niagara River are also polluted.
In 2005 NCC launched a conservation blueprint for terrestrial and freshwater biodiversity for the Ontario portion of the Great Lakes. The primary partner in this work was the Ontario Ministry of Natural Resources.
