Wetlands of the Great Lakes

The beach swale - north photo

The coastal wetlands of Lake Huron consist of several types that have distinctive geomorphological features and hydraulic regimes. Most are connected to the main lake in one way or the other. When water levels are high, the wetland is flooded. When water levels are low, the wetland begins to dry up. It is this random cycle of ups and downs that create conditions in a Great Lakes wetland that are very different from an inland wetland.

These web pages will take you on a tour of some Lake Huron wetlands and explain some of the features. For information on the details, see the book Wetlands of the Great Lakes. See the map below for Great Lakes wetlands of the United States greater than 40 acres.

A Typical Great Lakes Wetland

A Great Lakes wetland is any wetland directly connected to one of the Lakes, and experiences the same changes in water levels. A coastal wetland is any wetland that meets the above criteria, and any wetland within 1,000 feet of a Great Lake. Thus a diked wetland, with no natural means to follow the lake level, is not a Great Lakes wetland, but is a coastal wetland. A dug wetland, or a swale, some 900 feet from a Great Lake shore, is a coastal wetland but not a Great Lake wetland.

A classical Great Lakes wetland has the general arrangement of ecotypes (or ecozones) shown above. Not all zones may be present in every wetland however. The rising and falling of the water on a seasonal basis and over longer periods, creates a dynamic system of change that does not allow much aging. When water levels trend low, the uplands and shrubs "migrate" lakeward. When levels average high, the wet meadow gets flooded out and the shore shrubs experience die back.

Each of the zones shown above in the diagram have specific characteristics and subtle differences that determine the hydrophytic vegetation present. While there may be blends of the zones at the edges and occasional disruptions due to hummocks or levies in the wetlands; the patterns are repeated for the most part in every Great Lakes Wetland. It is the slope of the wetland from open water to highland that determines the breadth of these zones. They all parallel the shoreline, sort of band-like. It is these zones which give the wetlands such great diversity in plant life and homes for wildlife of all levels. The key to identifying each zone is the plant life that grows there. Inland wetlands have very limited water level change, and usually steeper slopes than Great Lakes wetlands; thus distinct bands or ecozones are often absent, or very reduced . All this is very complicated and too detailed for web site descriptions, so if interested, see the references mentioned.

The definitions above allow the wetlands shown on the left figure to be identified around the Great Lakes. Many have some characteristics of the others. Thus it is not uncommon to see features of several types being blurred into some shore configuration that does not seem to match any one precisely. The type of coast line, the elevation and the orientation determines which type will be common there. Overall, the most rare type is the delta. Diked wetlands are very common along some shores. Many Great Lakes wetlands do not resemble typical marshes at all and many shore owners have difficulty appreciating the delicate nature and value of the shore zone to wildlife and plants. Forested swamps, separated from the Lakes, are very common along some shores. They may be a coastal wetlands, but they are usually not a Great Lakes wetland. Of course they are very important, like ponds and lakes, but not included in these web sites.

These web pages will take you on a visual tour of the Great Lakes wetlands, click on any name to go there. We are always looking for high quality photos of plants, shore scenes and wildlife. If you would like to share some of your photographs, email us.

Click on any Lake above to see location of U. S. wetlands 40 acres or more.

Sedge Wren (previously known as short-billed marsh wren) is a common bird of the wet meadow and grassy areas. The marsh wren (long-billed marsh wren) is usually found in cattail marshes. It has a pronounced eye stripe and black stripes on the back.

Hear the call of the Sedge Wren

Credits, Notes and Links

Wetland photos courtesy of Walter J. Hoagman.
Bird photo courtesy of Steve Baker.

A Webfoot Page by MSU Sea Grant Extension, Northeast District, and MSUE, Iosco Co. Write Walter Hoagman with comments or suggestions. We need photos of other ships, birds, plants, etc. please help.

Additional links to Maritime History, Birds, Plants, Islands, Wetlands, Museums and other Great Lakes Info.