Wetlands are swamps, marshes, bogs, Carolina bays, floodplain bottoms and other areas where land is covered by shallow water at least part of the year. Wetlands, characterized by somewhat mucky soil, are home to a host of water-loving plants and animals. Wetlands can be transition zones between dry land and lakes, rivers or oceans; they share many characteristics of both environments. Some wetlands, such as Carolina bays, are isolated from any body of open water.
Wetlands range in size from thousands of acres to less than one acre. They occur just about anywhere, from the Arctic tundra to the humid tropical regions, in wooded areas or sunny, open, wet grasslands.
Once plentiful in the United States, wetlands are in serious decline now because of their loss to agriculture and commercial development. The United States has lost more than half of its original wetland areas. More than 400,000 acres are lost annually, even though development in wetlands is now regulated by the federal government.
People often view wetlands as worthless. Wetlands are sometimes drained and filled for development; others are polluted from dumping. But ecologists and others are beginning to get the message out that wetlands are some of the most biologically valuable ecosystems on earth and should be preserved.
Wetlands have numerous functions. Among them are:
1. Flood control: Wetlands, often called natural sponges, help control flood waters by absorbing water during heavy rainfall, then slowly releasing it downstream.
2. Water quality and availability: Like giant kidneys, wetlands help purify water by processing nutrients, suspended materials and other pollutants. Wetlands also increase the availability of water by absorbing and adding water in wet seasons, then gradually releasing it during dry periods.
3. Erosion control: Because they are often located between water bodies and high ground, wetlands buffer shorelands against erosion. Wetland plants also bind soil with their roots and help to absorb the impact from wave action.
4. Fish and wildlife habitat: Most fish and shellfish eaten by humans live in wetlands when they are young. Wildlife also migrate through wetlands, and many endangered species, such as the wood stork, live there, as do many other birds, amphibians, reptiles and mammals.
5. Recreation: Wetlands attract hunters, fishermen, hikers and boaters. Wetlands are also havens for bird watchers and provide scenic inspiration for artists and writers.
The University of Georgia's Savannah River Ecology Laboratory (SREL) located at the Savannah River Site near Aiken, S.C., has conducted wetlands and other ecological research for several decades. One of the most studied wetland types is the Carolina bay, found primarily in Georgia and the Carolinas.
Carolina bays are naturally occurring shallow depressions of an elliptical shape. They are typically isolated wetlands that are largely fed by rain and shallow groundwater. Researchers believe they are 10,000 years old or older. Some are wet all year, while others fill with water, then dry up, depending on the season.
Researchers have counted 194 Carolina bays on the Savannah River Site. These and other Carolina bays host a variety of plant and wildlife, providing a valuable habitat for such animals as frogs, salamanders, turtles, snakes and alligators. Also mammals such as deer, raccoons, skunks and opossums are believed to get food and water from Carolina bays. Amphibians, such as salamanders and frogs, are the most abundant wildlife found in Carolina bays.
Plants found in Carolina bays include loblolly and longleaf pines; black gum and sweet gum trees; blackjack and turkey oak trees; and shrubs such as sumac, gallberry and red bay. Also common in Carolina bays are broomsedge, water lilies and three-awn grass.
Researchers have also looked at the abundant microscopic organisms that live in Carolina bays. They are totally dependent on water to survive. Given the changing water levels of Carolina bays, Dr. Barbara Taylor, an assistant ecologist at SREL, is looking at how these microscopic organisms adapt to that extreme variability. She is developing a computerbased model that could predict the effects of climatic change -- particularly global warming -- on these and other biological communities.
The Environmental Protection Agency offers a toll free hotline that is responsive to public interest, questions and requests for information about the values and functions of wetlands and options for their protection. The hotline operates from 9 a.m. to 5:30 p.m., Eastern Time Zone, on weekdays. Callers within the United States, Puerto Rico and the U.S. Virgin Islands may reach the hotline by calling 1-800-832-7828.
This fact sheet was produced by the Outreach Program of the Savannah River Ecology Laboratory.
Last review: October 12, 2007