Freshwater Marshes

The Great egret (Casmerodius albus) winters in the tidal marshes along the Gulf Coast. Photo by  USGS photographer David Seawell.

Florida's freshwater marshes are non-tidal systems dominated by grasses, sedges and other emergent hydrophytes. These wetlands are non-forested and have non-peat soils (unlike bogs and fens). They are periodically or continually flooded. The water chemistry in Florida's marshes depends on nearby water sources. They can be either fresh water mineralized marshes (from groundwater, streams and surface runoff) or poorly mineralized fresh water marshes (results from direct precipitation).

Marsh wildlife: Common invertebrates in this detrital ecosystem are true flies including midges, mosquitoes, and crane flies. Nematodes and enchytraceids are important decomposers in the system. Dominant mammal species include herbivores such as muskrats, shrews and mice. Waterfowl are distributed throughout the ecosystem along an elevation gradient, according to water adaptations. Abundant species include ducks, geese, swans, songbirds, swallows and black ducks. Although the shallow marshes do not support many fish, deeper marshes are home to many species, including northern pike and carp.

Marsh vegetation: Characterized by tall reed plants, Typha and Phragmites grasses, Panicum and Cladium sedges, Cypress and Carex trees, Nymphea and Nelumbo floating aquatic plants.

Marsh soil characteristics: Inland marshes have alkaline soils with high concentrations of calcium and minerals. These soils are highly productive and have high microbial activity, which contributes to rapid decomposition, rapid recycling and rapid nitrogen fixation. Coarser soils like sand are found in marshes near waves or flowing water, but in more protected areas clays with decomposed organic material are more common.

Well-known marshes : The Florida Everglades is the single largest marsh system in the United States, occupying almost 10,000 square kilometers. Much of the land has been lost to development, but 4,200 square kilometers have been preserved, much of it as sawgrass marshes. The Everglades are threatened by altered water cycles caused by human development, drainage for development and polluted agriculture runoff.

For more information about the Florida Everglades, visit the Everglades section.

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