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.))
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 marsh-like characteristics with little open water)
5- Artificial (human-made/anthropogenic)
The Ramsar Convention added the following categories:
6. Human-made sites based on the physical appearance of wetlands.
7. Human-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
The classified under the definition of "ecotone" (transitional zone) due to their location at the interface of land and open water.
"The Prairie potholes"
The depressions found in central North America that rely primarily on rainwater or groundwater for replenishment and are not connected to a specific body of water.
"The Carolina bays"
The oval-shaped depressions located on the Atlantic coastal plain. There are also types that constitute a prominent feature of the regional landscape.
The (bogs)
It is a type of wetland fed by groundwater or surface water rich in dissolved minerals—unlike acidic bogs, which rely primarily on rainwater. Its waters are rich in minerals such as calcium and magnesium, and it has a lower acidity level than bogs, making it relatively alkaline or neutral; consequently, it supports greater plant diversity due to the abundance of nutrients.
The Fens
Fens are a type of wetland fed by groundwater or surface water rich in dissolved minerals—unlike bogs, which rely primarily on rainwater. Their waters are rich in minerals such as calcium and magnesium, and they have lower acidity levels than bogs, making them relatively alkaline or neutral; consequently, they support greater plant diversity due to the abundance of nutrients. Layers of peat accumulate in fens, though at a rate and with a composition that differ from those found in bogs.
المسطحات الطينية (مناطق المد والجزر)
المسطحات الطينية هي مناطق مسطحة نسبياً تخلو من الغطاء النباتي، وتقع بين المستنقعات الملحية (التي تغمرها المياه عند المد) والمياه العميقة. وتوجد هذه المسطحات في مناطق محمية نوعاً ما وتتميز بحركة أمواج محدودة، رغم أنها تظل عرضة لتأثيرات الرياح والأمواج والتيارات المائية. وتُعد رواسب هذه المناطق غير مستقرة للغاية، كما أن الطاقة الفيزيائية ومدة الغمر بالمياه تفوق قدرة المجتمعات النباتية الكبيرة على الاستقرار والنمو فيها. وتنتشر هذه المسطحات الطينية في أنحاء مختلفة من العالم، مثل الأراضي المنخفضة لنهر سانت لورانس، والمناطق المحاذية لمروج الأعشاب البحرية قبالة سواحل المكسيك، وفي خليج هدسون بكندا.
What is the importance of wetlands?
The wetlands are important features of the natural landscape, providing numerous beneficial services to humans, fish, and wildlife.
Some of these services—or functions—include
The atmospheric balance (wetlands may serve this additional function 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;
And maintaining surface water flow during periods of drought.
These valuable functions are attributed to 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 organisms, including microbes, plants, insects, amphibians, reptiles, birds, fish, and mammals. Crucial factors—such as
climate,
topography,
geology,
and water movement and availability—
play a role in determining the plant and animal species that inhabit each wetland area. The complex, dynamic relationships among the organisms living in a wetland environment are known as "food webs"; this explains why the characteristics of wetlands in states like Texas, North Carolina, and Alaska differ from one another.
The wetlands can be viewed as "biological supermarkets,"
as they provide abundant food that attracts 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 small 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 food 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 the 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 periods. Furthermore, the microbes, plants, and wildlife found in wetlands are integral components of global water, nitrogen, and sulfur cycles.
We derive a vast array of natural products from wetlands, including fish
The shellfish, blueberries, cranberries, timber, and wild rice; furthermore, certain medicines are extracted from wetland soils and plants. Many of the country's fishing and shellfish industries rely on species dependent on wetlands; in the southeast, for instance, fish and shellfish that rely on coastal wetland and estuary systems account for nearly the entire commercial catch and more than half of the recreational catch. Louisiana's coastal marshes are of immense value to commercial fishing and shellfishing. Wetlands also 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 the endangered species in the United States live exclusively in wetlands, while nearly half utilize wetlands at some stage of their lives; many other animals and plants also rely on wetlands for survival. Fish and shellfish inhabiting estuaries and marine waters, along with numerous bird species and certain mammals, depend on coastal wetlands to survive. Most commercial and recreational fish species spawn and rear their young in coastal marshes and estuaries. Common fish species that rely on coastal wetlands include menhaden, flounder, trout, spot, croaker, and striped bass. Shrimp, oysters, mussels, blue crabs, and Dungeness crabs also require 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 live.
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 as areas 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, their 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, reducing flood crests (peak levels) and mitigating erosion (flow velocity).
The wetlands located within urban areas and downstream are particularly valuable;
they help mitigate the significant increase in the rate and volume of surface runoff from pavements and buildings. Their water-retention capacity aids in flood control and prevents crop waterlogging. Often, the preservation and restoration of wetlands—alongside other water-retention measures—provide a level of flood control comparable to that achieved through costly dredging and dam construction. Historically, the hardwood bottomland wetlands along the Mississippi River stored floodwaters for at least 60 days; today, however, they store water for only 12 days, as most of these wetlands have been filled in or drained.
The challenges Facing Wetlands
The natural disturbances affecting wetlands include...
Contamination by agricultural chemicals...
...is common in many regions; pesticide-laden runoff can impact the entire wetland food web, often harming insects, aquatic arthropods, or herbaceous plants.
The fertilizer runoff into nearby waterways...
...can lead to eutrophication (nutrient accumulation) and the subsequent rapid proliferation of algae.
If these wetlands were to dry out, they would release carbon dioxide and methane back into the atmosphere
The plant communities have long adapted to climate change over millennia; however, human-induced climate change is occurring at an accelerated pace, triggering unpredictable shifts—including plant migration, altered interactions, invasions, and population declines. While models designed to track climate change dynamics lack the precision to predict the fate of any specific wetland, certain general trends are anticipated. Globally, wetlands play a neutral role regarding climate change: peatlands emit methane, yet they simultaneously store between 15 and 30 percent of the world's soil carbon. However, should rising temperatures cause peatlands to decompose, they would release two greenhouse gases—carbon dioxide and methane—thereby 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 that disrupt the balance of native wetland ecosystems. Meanwhile, in South Florida, the Burmese python (*Python bivittatus*)—a species native to Southeast Asia—has been competing with the American alligator (*Alligator mississippiensis*) for dominance since the 1990s, devastating mammal populations in the Everglades.
The cyclones periodically cause
mangrove trees to fall.
The erosion and sedimentation act
As complementary processes in active floodplains, where water flow shifts and a mosaic of vegetation patches forms. Beavers alter wooded landscapes by felling trees for dam construction and by impounding stream water.
The small, localized fires ignited by lightning
These 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 withstand grazing by muskrats.
Seasonal flooding
Tidal inundation
Waves
Cyclones
Fire
Drought
Grazing
Ice scour
Erosion
Sedimentation
Beaver activity
Inundation of river floodplains
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.
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