Estuaries and Wetlands

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Estuaries are two special ecosystems that tend to overlap between marine and freshwater zones. An estuary is a “partially enclosed area of coastal water where sea water mixes with fresh water and nutrients from rivers, streams, and runoff” (Miller). Wetlands are areas on land that can be covered with water. They can be either coastal wetlands (such as bays, sounds, mangrove forests, and salt marshes) or inland wetlands covered by fresh water (such as marshes, swamps, floodplains, bogs, and fens).

Estuaries and Wetlands play an important role in the environment. Some of the many services they perform include: acting as breeding grounds and habitats for many organisms, improving water quality by filtering nutrients and pollutants, providing recreation for humans, controlling floods and erosion, absorbing carbon dioxide as part of biogeochemical cycles, providing natural products that are useful to humans, and replenishing streams. Many of these services stem from the fact that estuaries and wetlands serve as an intermediary between different sources of water.

Since 1800, 50% of all estuaries and wetlands have been destroyed or damaged. This damage is caused by dredging, filling in these ecosystems in order to develop the area, contaminating them with sewage discharge, land runoff, and airborne pollutants. Because wetlands fulfill a crucial role in the environment, they must be protected from further damage. The provisions and regulations in the Clean Water Act help fulfill this purpose. Non-regulatory conservation involves a relationship between citizens and government; the government provides individuals and organizations with the funds and technology for wetland restoration. These programs have been highly effective. For example, in 2000, 1.96 million acres of wetlands were preserved. Volunteer efforts can contribute to wetland protection as well. Two Oregonians, Dan and Kathy Ridgeway, repaired 260 crew of wetlands along 2.5 miles of the Sprague River with the support of the government.

Types of Wetlands

Salt marshes: marshes along the coast at river mouths, on coastal plains, and around lagoons, usually found with estuaries. Examples: Chesapeake Bay, San Francisco Bay, Long Island Sound.
Coastal fresh marshes: marshes located directly inland from salt marshes. Tides affect water movement, but salt levels are low.
Vernal pools: pools that fill up in the spring and dry up in the summer. They are usually not connected to other water bodies and serve as breeding grounds, but they do not contain any fish. Vernal pools are a type of marsh.
Prairie potholes: shalow depressions formed by retreating glaciers from the Ice Age. They are found in the USA in the upper Midwest and North and South Dakota. Prairie potholes are a type of marsh.
Swamps: dominated by woody shrubs and trees, unlike marshes, which are dominated by water and salt-tolerant grasses. There are forested swamps (shrubs and plants grow beneath a forest canopy of trees) and shrub swamps. Shrub swamps can be permanent or they can eventually turn into forested swamps. They include mangrove swamps.
Bogs: peatlands formed by plant decomposition, especially areas with acidic soil or poor drainage. The peat forms a mass of vegetation floating on the water.
Pocosins: boggy shrub wetlands found along a coastal plain. They are found in the USA from Virginia to South Carolina. Pocosins are a type of bog.
Forested floodplain wetlands: wetlands that occur along larger rivers.