Wetlands are low lying areas where water is always at or just below the surface. Types of wetlands include rivers, streams and swamps.
Wetlands above Limantour Estero. Credit: Jessica Weinberg via San Francisco National Parks Science and Learning http://www.sfnps.org/node/4626
Why do we need wetlands?
Wetlands are important because they are a home to many species of plants and animals. Many organisms use wetlands to feed and reproduce. Wetlands are also important because they provide humans with many ecosystem services. Wetlands regulate flooding in local areas. They act like a sponge, soaking up incoming water. They also help protect shorelines from eroding or washing away. Wetlands also filter toxic chemicals out of water, helping to "purify" water for drinking. Wetlands also serve a cultural service to us by providing a place for outdoor activities, such as fishing, hiking, scientific and educational investigation, and bird watching.
Nutrient retention and Water Purification
Wetlands help balance terrestrial (on land) and aquatic (in water) ecosystems by retaining nutrients. The nutrients are stored in the plants and animals of the wetlands until they die or are taken by humans. When the organisms die, the nutrients are cycled back into the system by decomposers. This process keeps wetlands biodiverse, which in turn helps regulate other things like flooding, water purification, and climate.
Many wetlands have something called "biofilters," much like a filter in a fish tank. In the wetlands, these filters are most often plants that remove toxic substances that have come from pesticides, industrial waste, and mining. They do this through their stems, roots, and leaves. They store "heavy metals" like iron and copper commonly found in water waste from factories. Some animals can also do this, such as oysters. Oysters can filter more than 200 liters (53 gallons) of water per day, taking up nutrients and toxic chemicals while grazing for food.
Why do we need wetlands? U.S. Army Corps of Engineers Sacramento District project manager James Robb uses a watershed model Sep. 3, 2011, to show how wetlands filter water pollutants during a public outreach event in Loomis, Calif. Source: YouTube
Fabulous Wetlands with Bill Nye The Science Guy (1989). Published on Sep 21, 2012 (Recorded in 1989) A wacky and entertaining video featuring Bill Nye "The Science Guy" talking about the importance of wetlands. Produced by the Washington State Department of Ecology with funds from the National Oceanic Administration (NOAA) under the Coastal Zone Management Act. Go to http://www.ecy.wa.gov/programs/sea/we... for more information on wetlands. Source: YouTube
What are the human threats to wetlands?
Humans cause permanent damage to wetlands, sometimes damaging entire ecosystems. Humans change where water naturally flows by building dams and diverting rivers and streams to other places. This prevents water from getting to wetlands, making them dry out. Air and water pollution are also threats to wetlands, as chemicals dumped in or absorbed by the water are also absorbed by plant and animal life, often killing them. Not only would the loss of wetlands mean the loss of biodiversity and very likely the extinction of many species, but it would also mean more flooding and increases in air and water pollution in nearby communities.
New Orleans Flooded. Credit: "Navy-FloodedNewOrleans" by Jeremy L. Grisham - U.S. Navy. Licensed under Public Domain via Commons - https://commons.wikimedia.org/wiki/File:Navy-FloodedNewOrleans.jpg#/media/File:Navy-FloodedNewOrleans.jpg