Water management engineering developments in the past century have degraded these wetlands through the construction on artificial embankments. These constructions may be classified as dykes, bunds, levees, weirs, barrages and dams but serve the single purpose of concentrating water into a select source or area. Wetland water sources that were once spread slowly over a large, shallow area are pooled into deep, concentrated locations.
Loss of wetland floodplains results in more severe and damaging flooding. Catastrophic human impact in the Mississippi River floodplains was seen in death of several hundred individuals during a levee breach in New Orleans caused by Hurricane Katrina.
The surface water which is the water visibly seen in wetland systems only represents a portion of the overall water cycle which also includes atmospheric water and groundwater. Wetland systems are directly linked to groundwater and a crucial regulator of both the quantity and quality of water found below the ground. Wetland systems that are made of permeable sediments like limestone or occur in areas with highly variable and fluctuating water tables especially have a role in groundwater replenishment or water recharge.
Wetlands can also act as recharge areas when the surrounding water table is low and as a discharge zone when it is too high. Karst cave systems are a unique example of this system and are a connection of underground rivers influenced by rain and other forms of precipitation.
These wetland systems are capable of regulating changes in the water table on upwards of metres ft. Groundwater is an important source of water for drinking and irrigation of crops. Unsustainable abstraction of groundwater has become a major concern. In the Commonwealth of Australia, water licensing is being implemented to control use of the water in major agricultural regions. On a global scale, groundwater deficits and water scarcity is one of the most pressing concerns facing the 21st century.
Tidal and inter-tidal wetland systems protect and stabilize coastal zones. Coral reefs provide a protective barrier to coastal shoreline. Mangroves stabilize the coastal zone from the interior and will migrate with the shoreline to remain adjacent to the boundary of the water.
The main conservation benefit these systems have against storms and tidal waves is the ability to reduce the speed and height of waves and floodwaters. The sheer number of people who live and work near the coast is expected to grow immensely over the next 50 years. From an estimated million people that currently live in low-lying coastal regions, the development of urban coastal centers is projected to increase the population by 5 fold within 50 years.
This management technique provides shoreline protection through restoration of natural wetlands rather than through applied engineering. Nutrient Retention. Wetlands cycle both sediments and nutrients balancing terrestrial and aquatic ecosystems. A natural function of wetland vegetation is the up-take and storage of nutrients found in the surrounding soil and water. These nutrients are retained in the system until the plant dies or is harvested by animals or humans. Wetland vegetation productivity is linked to the climate, wetland type, and nutrient availability.
The grasses of fertile floodplains such as the Nile produce the highest yield including plants such as Arundo donax giant reed , Cyperus papyrus papyrus , Phragmites reed and Typha cattail, bulrush. Sediment Traps. Rainfall run-off is responsible for moving sediment through waterways. These sediments move towards larger and more sizable waterways through a natural process that moves water towards oceans. All types of sediments which may be composed of clay, sand, silt, and rock can be carried into wetland systems through this process.
Reedbeds or forests located in wetlands act as physical barriers to slow waterflow and trap sediment. Water purification. Many wetland systems possess biofilters, hydrophytes, and organisms that in addition to nutrient up-take abilities have the capacity to remove toxic substances that have come from pesticides, industrial discharges, and mining activities. The up-take occurs through most parts of the plant including the stems, roots, and leaves. Floating plants can absorb and filter heavy metals.
Eichhornia crassipes water hyacinth , Lemna duckweed and Azolla water fern store iron and copper commonly found in wastewater. Many fast-growing plants rooted in the soils of wetlands such as Typha cattail and Phragmites reed also aid in the role of heavy metal up-take.
Animals such as the oyster can filter more than liters 53 gallons of water per day while grazing for food, removing nutrients, suspended sediments, and chemical contaminants in the process. The ability of wetland systems to store nutrients and trap sediment is highly efficient and effective but each system has a threshold. An overabundance of nutrient input from fertilizer run-off, sewage effluent, or non-point pollution will cause eutrophication.
Upstream erosion from deforestation can overwhelm wetlands making them shrink in size and see dramatic biodiversity loss through excessive sedimentation load. The capacity of wetland vegetation to store heavy metals is affected by waterflow, number of hectares acres , climate, and type of plant.
Introduced hydrophytes in different wetland systems can have devastating results. The introduction of water hyacinth, a native plant of South America into Lake Victoria in East Africa as well as duckweed into non-native areas of Queensland, Australia, have overtaken entire wetland systems suffocating the ecosystem due to their phenomenal growth rate and ability to float and grow on the surface of the water.
The function of most natural wetland systems is not to manage to wastewater, however, their high potential for the filtering and the treatment of pollutants has been recognized by environmental engineers that specialize in the area of wastewater treatment. These constructed artificial wetland systems are highly controlled environments that intend to mimic the occurrences of soil, flora, and microorganisms in natural wetlands to aid in treating wastewater effluent.
Artificial wetlands provide the ability to experiment with flow regimes, micro-biotic composition, and flora in order to produce the most efficient treatment process. Other advantages are the control of retention times and hydraulic channels. Constructed wetland systems can be surface flow systems with only free-floating macrophytes, floating-leaved macrophytes, or submerged macrophytes; however, typical free water surface systems are usually constructed with emergent macrophytes.
The Urrbrae Wetland in Australia was constructed for urban flood control and environmental education. Kolkata is an example of how constructed wetlands are being utilized in developing countries. Using the purification capacity of wetlands, the Indian city of Kolkata Calcutta has pioneered a system of sewage disposal that is both efficient and environmentally friendly. Built to house one million people, Kolkata is now home to over 10 million, many living in slums.
Through a series of natural treatment processes — including the use of Eichhornia crassipes and other plants for absorbing oil, grease and heavy metals — the Cooperative has turned the area into a thriving fish farm and nature park.
Hundred of thousands of animal species, 20, of them vertebrates, are living in wetland systems. The discovery rate of fresh water fish is at new species per year. Biodiverse river basins. The Amazon holds 3, species of fresh water fish species within the boundaries of its basin whose function it is to disperse the seeds of trees.
One of its key species, the Piramutaba catfish, Brachyplatystoma vaillantii , migrates more than 3, km 2, miles from its nursery grounds near the mouth of the Amazon River to its spawning grounds in Andean tributaries m or yards above sea level distributing plants seed along the route.
Productive intertidal zones. Intertidal mudflats have a similar productivity even while possessing a low number of species. The abundance of invertebrates found within the mud are a food source for migratory waterfowl. Critical life-stage habitat. Mudflats, saltmarshes, mangroves, and seagrass beds contain bother species richness and productivity, and are home to important nursery areas for many commercial fish stocks. Genetic Diversity. Many species in wetland systems are unique due to the long period of time that the ecosystem has been physically isolated from other aquatic sources.
The number of endemic species in Lake Baikal in Russia classifies it as a hotspot for biodiversity and one of the most biodiverse wetlands in the entire world. Lake Baikal. Evidence from a research study by Mazepova et al. Its species of free-living Platyhelminthes alone is analogous to the entire number in all of Eastern Siberia. The 34 species and subspecies number of Baikal sculpins is more than twice the number of the analogous fauna that inhabits Eurasia.
One of most exciting discoveries was made by A. Shoshin who registered about species of free-living nematodes using only 6 near-shore sampling localities in the Southern Baikal. Human Impact. Biodiversity loss occurs in wetland systems through land use changes, habitat destruction, pollution, exploitation of resources, and invasive species.
The impact of maintaining biodiversity is seen at the local level through job creation, sustainability, and community productivity. Supporting over 55 million people, the sustainability of the region is enhanced through wildlife tours. Sustainable harvesting for medicinal remedies found in native wetlands plants in the Caribbean and Australia include the Red Mangrove Rhizophora mangle which possesses antibacterial, wound-healing, anti-ulcer effects, and antioxidant properties. Wetland systems naturally produce an array of vegetation and other ecological products that can harvested for personal and commercial use.
The most significant of these is fish which have all or part of their life-cycle occur within a wetland system. Food converted to sweeteners and carbohydrates include the sago palm of Asia and Africa cooking oil , the nipa palm of Asia sugar, vinegar, alcohol, and fodder and honey collection from mangroves. More than supplemental dietary intake, this produce sustains entire villages. Coastal Thailand villages earn the key portion of their income from sugar production while the country of Cuba relocates more than 30, hives each year to track the seasonal flowering of the mangrove Avicennia.
Over-fishing is the major problem for sustainable use of wetlands. Industrial-scale production of palm oil threatens the biodiversity of wetland ecosystems in parts of south-east Asia, Africa, and other developing countries. Exploitation can occur at the community level as is sometimes seen throughout coastal villages of Southern Thailand where each resident may obtain for themselves every consumable of the mangrove forest fuelwood, timber, honey, resins, crab, and shellfish which then becomes threatened through increasing population and continual harvest.
Other issues that occur on a global level include an uneven contribution to climate change, point and non-point pollution, and air and water quality issues due to destructive wetland practices. Wetlands perform two important functions in relation to climate change. They have mitigation effects through their ability to sink carbon, and adaptation effects through their ability to store and regulate water.
Carbon sequestration has sponsored blue carbon initiatives. More on blue carbon and carbon sequestration. In contrast, high water during deluges lake marsh phase causes turnover in plant populations and creates greater interspersion of element cover and open water, but lowers overall productivity. During a cover cycle that ranges from open water to complete vegetation cover, annual net primary productivity may vary fold.
Coastal wetlands, such as tropical mangroves and temperate salt marshes are known to be sinks of carbon, therefore mitigating climate change, however they are also emitters of nitrous oxide N 2 O , [49] which is a greenhouse gas with a global warming potential times that of carbon dioxide and the dominant ozone depleting substance emitted in the 21st century.
Although wetlands act as natural buffers towards nutrients expelled from surrounding watersheds, excess nutrients mainly through anthropogenic sources have been shown to significantly increase the N 2 O fluxes fluxes from their soils through denitrification and nitrification processes Table 1. A study in the intertidal region of a New England salt marsh showed that excess levels of nutrients might increase N 2 O emissions rather than sequester them.
Table 1. Nitrous oxide fluxes from different wetland soils. Table adapted from Moseman-Valtierra [57] and Chen et al. Nitrous oxide fluxes from wetlands in the southern hemisphere is lacking as are ecosystem based studies including the role of dominant organisms that alter sediment biogeochemistry.
Aquatic invertebrates produce ecologically relevant nitrous oxide emissions emissions due to ingestion of denitrifying bacteria that live within the subtidal sediment and water column [71] and thus may also be influencing nitrous oxide production within wetlands. Wetlands have historically been the victim of large draining efforts for real estate development, or flooding for use as recreational lakes. Wetlands are very effective at filtering and cleaning water pollution, [73] often from agricultural runoff from the farms that replaced the wetlands in the first place.
To replace these wetland ecosystem services enormous amounts of money had to be spent on water purification plants, along with the remediation measures for controlling floods: dam and levee construction. In order to produce sustainable wetlands, short-term, private-sector profits need to come secondary to global equity.
Decision-makers must valuate wetland type, provided ecosystem service, long-term benefit, and current subsidies inflating valuation on either the private or public sector side. Wetlands are vital ecosystems that provide livelihoods for the millions of people who live in and around them. The Millennium Development Goals MDGs called for different sectors to join forces to secure wetland environments in the context of sustainable development and improving human wellbeing.
A three-year project carried out by Wetlands International in partnership with the International Water Management Institute found that it is possible to conserve wetlands while improving the livelihoods of people living among them. Case studies conducted in Malawi and Zambia looked at how dambos — wet, grassy valleys or depressions where water seeps to the surface — can be farmed sustainably to improve livelihoods.
A wetland is an area of land that is either covered by water or saturate d with water. The water is often groundwater , seep ing up from an aquifer or spring. Seawater can also create wetlands, especially in coastal areas that experience strong tide s. A wetland is entirely covered by water at least part of the year. The depth and duration of this seasonal flooding varies. Wetlands are transition zone s. They are neither totally dry land nor totally underwater; they have characteristics of both.
The saturation of wetland soil determines the vegetation that surrounds it. Plants that live in wetlands are uniquely adapted to their watery hydric soil.
Wetland plants are called hydrophyte s. Seasonally dry wetlands or wetlands with slow-moving water can often support trees and other sturdy vegetation. More frequently flooded wetlands have mosses or grasses as their dominant hydrophytes. Wetlands exist in many kinds of climate s, on every continent except Antarctica. They vary in size from isolated prairie pothole s to huge salt marshes.
They are found along coasts and inland. Some wetlands are flooded woodlands, full of trees. Others are more like flat, watery grasslands. Still others are choked by thick, spongy mosses. Wetlands go by many names, such as swamps, peatlands, sloughs, marshes, muskegs, bogs, fens, potholes, and mires. Most scientists consider swamp s, marsh es, and bog s to be the three major kinds of wetlands. Swamps A swamp is a wetland permanently saturated with water and dominated by trees.
There are two main types of swamps: freshwater swamps and saltwater swamps. Freshwater swamps are common in inland areas. Saltwater swamps protect coasts from the open ocean. Freshwater Swamps Freshwater swamps often form on flat land around lakes or streams, where the water table is high and runoff is slow.
Seasonal flooding and rainwater cause the water level in these swamps to fluctuate , or change. Freshwater swamps are common in tropical areas near the Equator. These equatorial swamps usually experience year-round heat and humidity.
Tall evergreen trees dominate the swamp forests. Many species of these trees, such as bubinga and ovangkol, are harvested for timber.
Bubinga and ovangkol are expensive, luxury woods used to make musical instruments such as violins, as well as furniture. The thick canopy of trees means Congolian swamp forests are more shaded and humid than other wetlands. The muddy floor of these swamps is home to hundreds of insects, reptiles, and amphibians, including dozens of species of frogs.
Congolian swamp forests are also home to a wide variety of large mammals. Most of these mammals are herbivore s. Colobus and mangabey monkeys eat mostly tropical fruit. Other mammals, such as forest buffalo, forest elephants, and lowland gorillas, feed on the abundant vegetation of the wetland.
In fact, an adult male gorilla can eat up to 32 kilograms 45 pounds of leaves, fruit, and bark every day. In more temperate climates, cypress trees often grow out of the still waters of freshwater swamps.
Spanish moss may hang from tree branches. Willows and other shrubs may grow beneath the trees. Angular knobs called cypress knee s sometimes poke as much as 4 meters 13 feet above the water.
Scientists are not sure what purpose knees serve. They may simply provide support, or they may transport oxygen to the roots. Tiny water plants called duckweed often form a green cover on the surface of the water.
Alligators, frogs, and snakes called water moccasins may swim among the plants. Reptiles and amphibians thrive in freshwater swamps because they are adapted to the fluctuating water levels. Cypress swamps are common throughout the U. The bayou s of the state of Louisiana, near slow-moving parts of the Mississippi River, are probably the most famous American swamplands.
Shrimp, crawfish, wading birds, and fish such as catfish are native to bayous. Distinct cultures have also developed near bayous and other freshwater swamps.
In Louisiana, the food and music of Cajun culture is closely associated with bayou wildlife and imagery. Saltwater Swamps Saltwater swamps are usually found along tropical coastlines. Formation of these swamps begins with bare flats of mud or sand that are thinly covered by seawater during high tides. The brackish water of saltwater swamps is not entirely seawater, but not entirely freshwater, either.
Some hydrophytes, such as mangrove trees, can tolerate brackish water. Mangroves are easy to recognize because of their tall, stilt-like roots, which hold the small trunks and branches of the trees above water.
Mangrove roots anchor sediment and help soil accumulate around them. They also help build sediment through their growth and decay. Many organisms live among mangrove roots.
The root system provides shelter and a place to feed on fallen leaves and other material. Crabs, conchs, and other shellfish are abundant in mangrove swamps.
Saltwater swamps are also home to a huge variety of birds. Mangrove roots and branches provide excellent nesting site s. Saltwater swamps are home to seabirds, such as gulls, as well as freshwater birds, such as herons.
The abundance of plants, insects, and small animals provides food for these birds, whose droppings help fertilize the swamp. The Sundarbans, a saltwater swamp in India and Bangladesh, has the largest mangrove forest in the world.
Located on mud flat s near the delta of the Ganges River, the area is saturated in freshwater. The Sundarbans also experience strong tides from the Indian Ocean. The biodiversity of the Sundarbans stretches from tiny algae and moss to Bengal tigers. Dozens, perhaps hundreds, of different species of mangrove trees thrive in the Sundarbans. In drier areas of the swamp, palms and grasses grow. Insects such as bees build hives in the trees. In fact, harvesting honey has been a major economic activity in the Sundarbans for centuries.
Bees and other insects are one of the main food sources for tropical birds in the area. Storks, ibises, and herons nest in the high branches of mangrove and palm trees. Smaller birds such as kingfishers and pigeons roost in shrubs. Many reptiles and amphibians live in and around the swamp, including frogs, toads, turtles, and snakes. Some of the snakes of the Sundarbans, such as the Indian python, regularly grow up to 3 meters 10 feet long.
Monitor lizards and crocodiles, also native to the Sundarbans, are even larger. The large reptiles of the Sundarbans regularly prey on mammals such as deer, boar, mongooses, and monkeys. However, the most famous predator of the Sundarbans is the Bengal tiger, an endangered species. Bengal tigers are apex predator s—human beings are their only natural predator. In the Sundarbans, Bengal tigers swim in the swampy water and climb trees.
The cats, which can grow to kilograms pounds , have been known to attack people in the swamp. Scientists and honey collectors are especially at risk. Marshes North and south of the tropics, swamps give way to marshes. These wetlands form a flat, grassy fringe near river mouths, in bays, and along coastlines.
Many are alternately flooded and exposed by the movement of tides. Wetland soils—and the wetland's position in the cycle—collect and hold floodwaters, then slowly disperses them. Wetlands along the edges of open waters buffer the shoreline from erosion. Wetlands produce and recycle huge amounts of plant and animal life, much of which is passed on to adjacent land and water habitats.
Further, rich wetland ecosystems are critical permanent or nursery habitat for myriad species of plants and animals. As the state's population of Reduced summer water levels are likely to diminish the recharge of groundwater, cause streams to dry up, and reduce the area of wetlands, resulting in poorer water quality and less habitat for wildlife. For ducks, geese and other migratory birds, wetlands are the most important part of the migratory cycle, providing food, resting places and seasonal habitats.
Some of these birds use wetlands as a breeding ground, coming back every spring to mate and produce offspring. More than one-third of the United States' threatened and endangered species live only in wetlands, and nearly half use wetlands at some point in their lives.
Many other animals and plants depend on wetlands for survival. Estuarine and marine fish and shellfish, various birds, and certain mammals must have coastal wetlands to survive. Most commercial and game fish breed and raise their young in coastal marshes and estuaries.
Menhaden, flounder, sea trout, spot, croaker, and striped bass are among the more familiar fish that depend on coastal wetlands.
Shrimp, oysters, clams, and blue and Dungeness crabs likewise need these wetlands for food, shelter, and breeding grounds. For many animals and plants, like wood ducks, muskrat, cattails, and swamp rose, inland wetlands are the only places they can live. Beavers may actually create their own wetlands. For others, such as striped bass, peregrine falcon, otter, black bear, raccoon, and deer, wetlands provide important food, water, or shelter.
Many of the U. Migratory waterfowl use coastal and inland wetlands as resting, feeding, breeding, or nesting grounds for at least part of the year. Indeed, an international agreement to protect wetlands of international importance was developed because some species of migratory birds are completely dependent on certain wetlands and would become extinct if those wetlands were destroyed.
Reference: U.
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