General Information
The wetlands used to store floodwaters for at least 60 days; now, however, they store water for only 12 days, as most have been filled in or drained.
The Definition of Wetlands – According to the Ramsar Convention
The term "wetlands" was first used officially in 1953 in a report issued by the U.S. Fish and Wildlife Service (USFWS); this report established a framework for a subsequent publication addressing waterfowl habitats in the United States. Since then, definitions of wetlands have proliferated and varied according to the perspectives of ecologists and government officials. Although there is no single, universally accepted official definition, the definition established by the Ramsar Convention—an intergovernmental treaty signed in Ramsar, Iran, in 1971 to guide wetland conservation measures at national and international levels—is among the most widely cited and relied upon. It is as follows:
((The wetlands are areas of marsh, fen, peatland, or water—whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish, or salt—including areas of marine water the depth of which at low tide does not exceed six meters. This definition is broad enough to encompass open water bodies frequented by birds; a concept that served as the original impetus for advocating the protection of wetlands and associated aquatic sites.))ure?
The Types of Wetlands
The U.S. Fish and Wildlife Service (USFWS) has introduced a hierarchical system based on five ecosystem types:
1- Marine
2- Estuarine (associated with estuaries)
3- Riverine (associated with rivers) and Lacustrine (open water associated with lakes)
4- Palustrine (areas dominated by marshy characteristics with little open water)
5- Artificial (human-made/anthropogenic)
The Ramsar Convention added the following categories:
6- Man-made sites based on the physical appearance of wetlands.
7- Man-made sites based on function (i.e., hydrological systems and the role of wetlands within them).
There are other designations based on definitions distinct from those of the Ramsar Convention:
The tidal salt marshes
It's classified under the definition of a "transition zone" due to their location at the interface of land and open water.
"The Prairie potholes"
it's found in central North America; these are primarily fed by rainwater or groundwater and are not connected to a specific body of water.
The Carolina Bays
These are oval-shaped depressions located on the Atlantic coastal plain; they constitute a prominent feature of the regional landscape.
The Fens
These are a type of wetland fed by groundwater or surface water rich in dissolved minerals—unlike acidic bogs, which rely primarily on rainwater. Because their waters are rich in minerals such as calcium and magnesium, they are less acidic than bogs—tending to be relatively alkaline or neutral—and support greater plant diversity due to the abundance of nutrients.
The Mineral-rich wetlands (Fens)
The fens are a type of wetland fed by groundwater or surface water rich in dissolved minerals—unlike acidic bogs, which rely primarily on rainwater. Their waters contain minerals such as calcium and magnesium, and they are less acidic than bogs, tending to be relatively neutral or alkaline. They support greater plant diversity due to the abundance of nutrients. Layers of peat accumulate in fens, though the rate and composition of this accumulation differ from that of bogs.
The Mudflats (Intertidal zones)
The mudflats are relatively flat, unvegetated areas situated between salt marshes (which are submerged at high tide) and deeper water. They are typically found in somewhat sheltered areas characterized by limited wave action, although they remain exposed to the effects of wind, waves, and water currents. The sediments in these areas are highly unstable, and the physical energy and duration of inundation exceed the capacity of large plant communities to establish themselves and grow. Mudflats are found in various parts of the world, such as the St. Lawrence River lowlands, areas adjacent to seagrass meadows off the coast of Mexico, and Hudson Bay in Canada.
What is the importance of wetlands?
The wetlands are vital features of the natural landscape, providing numerous beneficial services to humans, fish, and wildlife.
These services—or functions—include
The atmospheric balance: Wetlands can play a role in this by storing carbon within their plant communities and soils rather than releasing it into the atmosphere as carbon dioxide, thereby helping to moderate global climate conditions.
Protecting and improving water quality.
Providing habitats for fish and wildlife.
Storing floodwaters.
Maintaining surface water flow during periods of drought.
These valuable functions stem from the unique natural characteristics of wetlands.
The Importance of Wetlands to Nature
The wetlands are among the most productive ecosystems in the world, rivaling rainforests and coral reefs. A wetland ecosystem can support a vast diversity of life, including microbes, plants, insects, amphibians, reptiles, birds, fish, and mammals. Crucial factors—such as climate, topography, geology, and water movement and availability—determine the specific plant and animal species that inhabit each wetland area. The complex, dynamic relationships among the organisms within a wetland environment are known as "food webs"; this explains why the characteristics of wetlands in states like Texas, North Carolina, ad Alaska differ from one another
The wetlands can be considered "biological supermarkets"
They provide vast quantities of food that attract numerous animal species relying on these areas for part or all of their life cycles. Dead plant leaves and stems decompose in the water, forming tiny particles of organic matter known as "detritus." This nutrient-rich material serves as a food source for many small aquatic insects, shellfish, and small fish, which in turn provide sustenance for larger predators such as fish, reptiles, amphibians, birds, and mammals.
The Importance of Wetlands to Humans
The functions and value of wetlands for humans depend on a complex set of relationships between these lands and other ecosystems within a watershed. A watershed is a geographic area where water, sediment, and dissolved substances collect and flow from higher elevations toward a common outlet or low-lying basin—such as a point in a larger watercourse, a lake, an aquifer, or an estuary. Wetlands play a vital role in the watershed ecosystem; the combination of shallow water, high nutrient levels, and primary productivity creates an ideal environment for the growth of organisms that form the base of the food web—organisms upon which numerous species of fish, amphibians, shellfish, and insects feed. Many bird and mammal species also rely on wetlands for food, water, and shelter, particularly during migration and breeding seasons. Furthermore, the microbes, plants, and wildlife found in wetlands are integral to global water, nitrogen, and sulfur cycles.
We benefit from wetlands through the production of a vast array of natural resources, including fish and shellfish, blueberries, cranberries, timber, and wild rice.
The certain medicines are also derived from wetland soils and plants.
Many of the country's fishing and shellfish industries rely on
The species dependent on wetlands; in the southeast, for example, fish and shellfish that rely on coastal wetland and estuary systems account for nearly all commercial catches and more than half of recreational catches. Louisiana's coastal marshes are of immense value to commercial fishing and shellfishing. Wetlands provide habitats for fur-bearing animals—such as muskrats, beavers, and mink—as well as for reptiles like alligators.
The Fish and Wildlife Habitats
More than one-third of endangered species
In the United States live exclusively in wetlands, and nearly half use wetlands at some stage of their lives; many other animals and plants also depend on wetlands for survival. Fish and shellfish inhabiting estuaries and marine waters, along with numerous birds and certain mammals, require coastal wetlands to survive. Most commercial and game fish spawn and rear their young in coastal marshes and estuaries. Among the most common fish dependent on coastal wetlands are menhaden, flounder, trout, spot, croaker, and striped bass. Shrimp, oysters, mussels, blue crabs, and Dungeness crabs also rely on these wetlands for food, shelter, and breeding grounds.
For many animals and plants—such as wood ducks, muskrats, sedges, and swamp roses—inland wetlands are the only places where they can survive.
The beavers may even create their own wetlands
For other animals—such as striped bass, peregrine falcons, otters, black bears, raccoons, and deer—wetlands provide food, water, and shelter.
Many bird species that breed in the United States—including ducks, geese, woodpeckers, hawks, wading birds, and numerous songbirds—build their nests and raise their young in wetlands. Migratory waterfowl utilize coastal and inland wetlands for resting, feeding, and breeding or nesting for at least part of the year. In fact, an international agreement was established to protect wetlands of international importance because certain migratory bird species rely entirely on specific wetlands and would face extinction if those areas were destroyed.
The wetlands act as natural sponges, absorbing rainwater, snowmelt, groundwater, and floodwaters, and then releasing them slowly. Trees, roots, and other wetland vegetation slow the flow of floodwaters, distributing them more gradually across the floodplain. This collective water storage acts as a buffer, lowering flood crests and mitigating erosion caused by high-velocity flows.
The wetlands located in urban areas and downstream are particularly valuable, as they help manage the significant increases in the rate and volume of surface runoff from pavement and buildings. Their capacity to retain water aids in flood control and prevents crops from becoming waterlogged. Conserving and restoring wetlands—along with other water-retention methods—often provides the same level of flood control as costly dredging and dam construction. Hardwood bottomland wetlands along the Mississippi River used to store floodwaters for at least 60 days; now, they store water for only 12 days, as most have been filled in or drained.
The challenges Facing Wetlands
The natural disturbances affecting wetlands include...
Pollution by agricultural chemicals is common in many regions; pesticide-laden runoff can impact the entire wetland food web, often harming insects, aquatic arthropods, and herbaceous plants.
The fertilizer runoff into nearby waterways...
It can lead to eutrophication (nutrient accumulation) and subsequent algal blooms.
If these wetlands were to dry out, they would release carbon dioxide and methane back into the atmosphere.
The Plant communities have responded to climate change over millennia; however, human-induced climate change is occurring at an accelerated pace, triggering unpredictable shifts—including plant migration, new interactions, invasions, and population declines. While models designed to track climate change dynamics lack the precision to predict the fate of a specific wetland, certain general changes are anticipated. Globally, wetlands are considered climate-neutral; peatlands, for instance, emit methane but simultaneously store between 15 and 30 percent of the world's soil carbon. However, if peatlands begin to decompose due to rising temperatures, two greenhouse gases—carbon dioxide and methane—will be released, contributing to further warming.
The Invasive Species
The Burmese python (*Python bivittatus*) is found in the waters of the Florida Everglades. These snakes have nearly wiped out many small mammals in the area—including rabbits, foxes, bobcats, raccoons, and opossums—as the introduction of non-native flora and fauna, whether intentional or accidental, has led to the establishment of invasive species in wetlands worldwide. In Australia, for example, the giant sensitive plant (*Mimosa pigra*) is believed to have been introduced via the Darwin Botanic Gardens prior to the 1890s; unpalatable to most wildlife, it forms dense thickets and disrupts the balance of native wetland ecosystems. Meanwhile, in South Florida, the Burmese python (*Python bivittatus*)—a species native to Southeast Asia—has competed with the American alligator (*Alligator mississippiensis*) for dominance since the 1990s, decimating mammal populations in the Everglades.
The Hurricanes periodically cause
The mangrove trees to fall.
The Erosion and sedimentation
The act as complementary processes on active floodplains, where shifting water flows create a mosaic of vegetation patches. Beavers alter wooded landscapes by felling trees for dam construction and by impounding stream waters. Small, lightning-ignited fires
These two phenomena create gaps believed to be essential for seedling growth. Fire-adapted wetlands include the Everglades, the St. Lawrence River marshes, and various peatlands. Prairie ponds in the Upper Midwest of the United States are adapted to drought and tolerate grazing by muskrats.
Seasonal flooding
Tidal inundation
Waves
Hurricanes
Fire
Drought
Grazing
Ice scour
Erosion
Sedimentation
Beaver activity
River floodplain inundation
The wetlands can easily be altered or destroyed; they can be cut off from their water sources through the modification of drainage areas or the construction of dams and water-retention barriers. Major U.S. cities—such as Chicago and Washington, D.C.—are situated on sites that were once partially covered by wetlands; however, as these cities expanded, most of those wetlands were drained, filled in, or otherwise fundamentally altered. Although it is nearly impossible to precisely quantify the global loss of wetlands, it is known that the United States—specifically the contiguous forty-eight states, a region of relatively recent development—has lost more than half of its original wetland area, primarily due to conversion into agricultural land.
How Wetlands Adapt to Natural Challenges
The coastal salt marshes and mangroves adapt to regular flooding and wave action, as well as sedimentation.
The Links
