Wetlands were once considered wastelands, land that developers could pave over and build on and that no one would miss. Now, we know better. What are wetlands and what role do they play in our ecosystem?

According to the United States Fish and Wildlife Service's National Wetlands Inventory,

Wetlands are lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or where shallow water covers the land and where at least one of the following attributes holds: 1) the land predominantly supports aquatic plants at least periodically; 2) undrained hydric soils are the predominant substrate; 3) at some time during the growing season, the substrate is saturated with water or covered by shallow water.

There are many different kinds of wetlands. Some of the common names may be familiar to you:

• Marshes are characterized by poorly drained mineral soils and by plant life dominated by grasses. They are commonly found at the mouths of rivers. There are three major types of marshes: tidal, freshwater, and saltwater.
  
  
• Swamps are characterized by poorly drained mineral soils and by plant life dominated by trees.
  
  
• Potholes are depressional wetlands found primarily in the upper Midwest. They were formed by glaciers in prehistoric times.
  
  
• Bogs are characterized by deposits of spongy peat and extensive growth of evergreen trees and shrubs. A bog floor is usually covered by a thick carpet of moss.
  
  
• Fens are peat-forming wetlands that support diverse plant and animal communities. They are often covered by grasses, sedges, reeds, and wildflowers. They are actually a type of open freshwater marsh that receives nutrients from upland sources, not from precipitation.
  
  
• Playa lakes are the flat-floored bottom of an undrained desert basin that at times becomes a shallow lake.

Wetlands play an important role in local ecosystems, supporting great biodiversity. The combination of shallow water, high levels of nutrients, and rich plant life is ideal for the development of organisms that form the base of the food web and feed many species of fish, amphibians, shellfish, and insects. Many species of birds and mammals rely on wetlands for food, water, and shelter, especially during migration and breeding.

Wetlands act like sponges, soaking up rain and excess floodwater runoff. One acre of wetlands stores up to 1.5 million gallons of flood waters. The wetlands then gradually feed this water back into streams, rivers, and other water sources. Areas where extensive wetlands destruction has occurred experience flooding because the wetlands no longer absorb the huge quantities of water that they once did. Some states—e.g., Ohio, Kentucky, California, and Missouri—have lost over 80% of their wetlands and severe flooding has become common there in recent years.

Scientists claim that wetlands not only contribute to our water supply, but they may also contribute to maintaining a healthy atmosphere. Wetlands store carbon within their plant communities and soil instead of releasing it into the atmosphere in the form of carbon dioxide, which contributes to global warming.

In January the United States Fish and Wildlife Service released its Wetlands Status and Trends Report. The news is mixed: even though there has been an 80% reduction in the rate at which America's wetlands are being destroyed, they are still disappearing at a rate of 585,000 acres annually. The loss of wetlands impacts all the species dependent on them, including humans.

The drop in rate of wetlands destruction is a result of federal, state, and local laws. The "Swampbuster" provisions of the Food Security Act of 1985 calls for withholding certain federal farm program benefits from farmers who convert or modify wetlands. In 1977 the United States Congress passed the Clean Water Act, which includes wetlands protection. These two laws have helped reduce the rate at which wetlands are converted to agriculture and other uses. In addition, a number of states have enacted laws to regulate activities in wetlands, and individual counties and towns have adopted local wetlands protection ordinances.

• Students can read the full report.

Teaching the Problem

Wetlands can provide a "case study" for studying concepts in different areas of science, such as food webs and ecosystems, habitat, climate, and water chemistry.

• You can find more information and ideas at the Environmental Protection Agency (EPA) site, America's Wetlands, designed specifically for students. The material is available in printable format (PDF) as well.
  
  
• The Riverdeep Current article, "Along the Food Chain," can be applied to a wetlands ecosystem.
  
  

• Students can respond in different forms of persuasive writing to the following scenario:
  
  Suppose the county in which you live is considering a proposal to allow a real estate developer to build an entertainment complex on local wetlands. Would you support the proposal? Why or why not?
  
  

Analyzing the Problem

Use the Wetlands Interactive Mapper Tool to generate a map of wetlands in the area of your school. Have students research local wetlands. (If there are no wetlands in your vicinity, then choose some from another location in your state.) Ask them to answer the following questions:

• How many acres do the wetlands cover today?
  
  
• How many acres did the wetlands cover before the nearest town was established?
  
  
• What type (e.g., marsh, swamp, etc.) are the wetlands?
  
  
• What are three typical plants that grow in the wetlands?
  
  
• What are three typical creatures found in the wetlands?
  
  
• How do the wetlands contribute to the water supply of your community?
  
  
• How has destruction of the wetlands affected your community?

1. The following sources provide general information on wetlands:
   
   
   • EPA's Wetlands: This comprehensive resource on wetlands includes educational materials.
     
     
   • USFWS's National Wetlands Inventory Center: The goal of the center and its Web site is to generate information about the characteristics, extent, and status of the nation's wetlands and deepwater habitats.
     
     
   • Sierra Club's Wetlands and Clean Water: The Sierra Club offers background information and opportunities for community action to save America's wetlands.
     
     
   • World Wildlife Fund's Spotlight: World Wetlands Week: This site was presented for Wetlands Week at the beginning of February, but the information is relevant year round.
     
     
   • National Wildlife Federation's Wetlands: This site offers a close look at some of the country's famous wetlands, including the Everglades, the Copper River delta, and the Texas coast wetlands.
     
     
2. You can find ideas for "field work" at the following sites:
   
   
   • United States Geological Survey's The Fragile Fringe: A Guide for Teaching about Coastal Wetlands: Lesson plans for classroom activities, mixed grade levels
     
     
   • National Wetlands Research Center's Wetland Science Lesson Plans: Biology and chemistry lessons for high school students
     
     
   • EPA's World in Our Backyard: An online book about wetlands, including classroom activity suggestions