What
Are Wetlands and Aquatic Habitats?
Wetlands are transitional areas, sandwiched between permanently flooded deepwater
environments and well-drained uplands. They include mangroves, marshes (salt,
brackish, intermediate, and fresh), swamps, forested wetlands, bogs, wet prairies,
prairie potholes, and vernal pools. They often contain more plants and animals
and produce more organic material than either the adjacent water or land areas.
Aquatic habitats include permanently flooded parts of estuaries and nearshore
environments like seagrass beds, rivers, ponds, and lakes. Aquatic habitats
are also critical to fish and wildlife as well as economically and recreationally
valuable to humans.
Why Are Wetlands and Aquatic Habitats Important?
Wetlands are among the most productive habitats on earth providing shelter
and nursery areas for commercially and recreationally important animals like
fish and shellfish, as well as wintering grounds for migrating birds. Coastal
marshes are particularly valuable for preventing loss of life and property
by moderating extreme floods and buffering the land from storms; they also
form natural reservoirs and help maintain desirable water quality.Aquatic
habitats like these along the Gulf of Mexico are vital to seabirds, fish,
and shellfish; economically the gulf alone contributes billions to the economy.
Riverine deep water-like the Mississippi River and its many channels-is not
only essential for navigation, industry, and recreation and therefore responsible
for billions of dollars to the economy, but is also invaluable for natural
resources. Songbirds and waterfowl use rivers as migratory guides, and rivers
and lakes are both essential to countless species of fish, amphibians like
frogs and salamanders, and reptiles like turtles, snakes, and alligators.
What's Happening to Wetlands and Aquatic Habitats?
But wetlands have come under natural and human threats (from subsiding or
sinking land to draining or filling for new development). Scientists estimate
that the lower 48 United States have lost more than half of their wetlands
since colonial times. Coastal wetlands especially have been seriously threatened.
For example, Louisiana alone has 40 percent of the coastal wetlands in the
lower 48 States and is still losing from 25 to 35 square miles a year of wetlands
to open water because of erosion and subsidence.
In addition to coastal wetlands, seagrasses in the estuaries along the coast of the Gulf of Mexico and worldwide have been depleted. Serious problems also include the tremendous loss of forested wetlands in the South; while they account for more than a third of all wetlands in the lower 48 states, they also account for two thirds of the annual loss of all wetlands in the continental United States. Wildlife, especially migratory birds like waterfowl and Neotropical birds have experienced population declines and distributional shifts, partly because of habitat alteration.
Rivers and other aquatic habitats have also undergone huge changes. They suffer impacts from various causes, ranging from dredging to both point and nonpoint source pollutants to contaminants. Estuaries have also seen enormous changes in water quality and structure from dredging, fringing urban development, industries, and shipping. All of these, in turn, change the ecological structure and functions of these habitats and their ability to support fish, shellfish, and wildlife.
Restoring these wetlands and improving aquatic habitats have become imperative
to maintaining an ecological balance. To restore and manage these valuable
wetlands and deepwater habitats, however, requires scientific research because
much remains unknown about which restoration and management techniques work
best and how restored ecosystems work compared to natural ones.
This document prepared by the National Wetlands Research Center
URL - http://www.nwrc.usgs.gov/wetlands.htm.
Last Modified: 11/03/2003 (SBH)
Contact: nwrcweb@usgs.gov