Wetland Ecosystems

The water cycle and our natural surroundings are vitally dependent on healthy wetlands. A wetland is an area that tends, at least periodically, to have waterlogged soils or is covered with a relatively shallow layer of water. These areas support plants and animals that are adapted to living in a watery environment.

Wetlands provide habitat for plants and animals. Many plants and animals are adapted to living in or near wetlands. We depend on some of these, such as fish, for food and sport. Waterfowl need wetlands for food, nesting, and resting places. Since wetland species are equipped to feed, reproduce, and find shelter in or near a wetland habitat, they cannot do the same away from a wetland.

For these plants and animals, a wetland habitat is a matter of life and death. A safe habitat is especially critical for plant and animal species that are having a hard time surviving. These endangered and threatened species are already low in numbers and may be clinging to life in just few wetland locations. If those wetlands are destroyed, then they may be pushed closer to extinction.

Wetlands filter and trap silt, litter, trash, and chemical pollutants. Wetlands work as natural filters. To understand how, picture an imaginary marsh. This large marsh is bordered on the west by a golf course, by a school on the east, and by residential streets on the south. Along its northern boundary, it drains to a small stream that eventually runs into a major river. When it rains, lots of pollutants run off the areas around the marsh into its water. Silt washes off from the golf course and runs into the marsh. Litter and trash from the school blow into the marsh. Fertilizers from nearby lawns in the housing subdivision pass through the soil into the marsh. And, finally, heavy metals and automobile by-products wash off the subdivision's streets and drain into the marsh.

Once the pollutants are in the marsh, they are trapped by the thick-growing herbs. The soil or silt, pesticides, metals, and automobile wastes settle to the bottom. The phosphates and nitrates in the fertilizers are broken down and recycled through the nutrient element cycle. By the time that water flows out of the marsh, through the stream, and into the river, many of the pollutants have been filtered out of the water and left behind in the marsh. Because of the marsh working as a filter, the water in the river is kept cleaner. This is not to say that wetlands, like the marsh, can filter any amount of pollutants and not be damaged. Every wetland reaches a cut-off point and once it reaches that point, it cannot absorb any more pollutants without being damaged. That is why we need to control the amount of pollutants that flow into our wetlands.

In Missouri and Illinois, our rivers flood each year. These floods often cause serious damage. The damage is lessened, however, due to the backwater wetlands such as lakes, swamps, and marshes along rivers. When a river floods, much of the water spills over into its backwater wetlands. These wetlands act like sponges and absorb the floodwater. This keeps the floodwater out of our cities and off our roads. Once the floods have peaked, the backwater wetlands release the floodwater slowly back into the river. As a bonus, some of the pollutants in the floodwater have been filtered and trapped in the backwater wetlands and never enter the river.

Wetlands provide food and water for humans. Wetlands provide some of the land that we need to live. We get our drinking water from rivers, lakes, and aquifers. We eat fish and other animals taken from the wetlands. The water is used even to irrigate some of the crops produced by Illinois and Missouri farmers. These crops help feed people all over the world and are an important part of our economy.

Wetlands provide opportunities for recreation and serve as living museums of our natural heritage. Wetlands give us a place to swim, fish, hunt, boat, or observe nature. In these wetlands we can study the beautiful plants and animals that live there.