Coastal Wetlands Background and Significance

Outer Island Sand Spit and Lagoon. Photograph by E.J. Epstein

Wetlands found near the coasts of the Great Lakes include marshes, bogs, fens, sedge meadows, shrub swamps, hardwood swamps, coniferous swamps, spring seeps, and others. Wetlands specific to the Great Lakes coasts include freshwater estuaries, interdunal wetlands, ridge and swale systems, and lakeplain prairies. While there is no universally accepted definition of a coastal wetland, there are some significant characteristics distinguishing them from their inland counterparts and other wetlands found along the coast. Coastal wetlands exist because of their historic and present-day interactions with the Great Lakes. They serve as spawning grounds for fish, stopovers or staging grounds for migratory and breeding birds, and critical habitat for many rare plants and animals.

The importance of wetlands for performing various ecological services is well documented, and they have long been recognized as one of the most important ecosystems on Earth (Mitsch and Gosselink 1993). They are sometimes characterized as the “kidneys” of the landscape because of their functions in hydrological and chemical cycles and because they intercept wastes from both natural and human sources. Wetlands play an important role in cleansing polluted waters, preventing floods, protecting shorelines, and recharging groundwater aquifers. Wetlands are also important as carbon sinks on a global scale.

Wetlands throughout Wisconsin provide critical habitat for a diverse set of both aquatic and terrestrial plant and animal species. A number of coastal wetland sites host extremely rich assemblages of flora and fauna, including dwarf lake iris (Iris lacustris) and Piping Plover (Charadrius melodius) both of which are rare globally. Some rare plant species such as the coast sedge (Carex exilis), English sundew (Drosera anglica) and marsh bedstraw (Galium palustre), a Wisconsin special concern species, are found only in coastal wetlands. Long-term monitoring stations along the Great Lakes have documented high concentrations of migratory birds, over 100 of which are Neotropical Migrants or birds that winter in the Neotropics or southward (Finch 1991). The Great Lakes serve as migrant corridors and coastal wetlands offer critical food and shelter resources. In addition, some of the larger forested wetlands along Lake Michigan serve as ecological refuges for breeding bird species that are now more commonly found in northern Wisconsin. Table 1 lists many of the rare plants and animals tracked by NHI that have been documented within the Primary Sites for this project along with their state and federal status, where applicable.

Coastal wetlands near Wisconsin’s Great Lakes include several important natural communities and other natural features such as Forested Ridge and Swale, Great Lakes Dunes, and Interdunal Wetlands. Many of the natural community types tracked by NHI that have been documented within the coastal study area for this project are listed. Brief descriptions of these community types can be found in Appendix C.

More Information:

The Lake Michigan Coastal Zone