Wetlands are under threat from drainage, reclamation projects and a deterioration in water quality due to human development efforts, particularly in agriculture and industry. There is an increasingly harmful build up of sediments and toxic chemical pollutants affecting fish and other types of aquatic life.
The evidence is increasing of poor quality water bodies affecting wild life, notably migratory birds and in particular their reproductive capacities.
Wetlands include marshes, bogs, fens, and all stretches of water, whether fresh or salt, static or flowing, temporary or permanent. These may be estuaries and marine shallows, brackish and saline lagoons, natural and artificial lakes, small ponds or pot-holes, reservoirs, flooded gravel pits, rivers, streams, flood-meadows, and swamps.
Wetland habitats support a vast range of plant and animal life, and serve a variety of important functions, the full value of which are even now only beginning to be recognized. (Functions include: water regime regulation, flood control, erosion control, nursery areas for food fishes, fish production, waterfowl production, recreation, plant production, aesthetic enjoyment, and wildlife habitat). Wetlands are atmospheric sinks for carbon dioxide and producers of methane.
Wetlands are a significant, but severely impacted, natural resource. Only since the late 1960's have wetlands engaged the attention of individuals from a range of disciplines who endeavour to understand their variety and complexity. Recent but intense interest in wetlands is due largely to their role in aquatic and terrestrial ecosystems, and our changing perceptions of them. Humans have come to understand how important wetlands are to the existence of numerous plants and animals, as well as the many functions they perform (e.g., flood control, ground water recharge, and maintenance of water quality) that are important to our quality of life.
If a wetland dries up, for whatever reason, the area may become a source of, rather than a sink for, toxic substances. Anaerobic conditions will be replaced by aerobic ones, and immobile sulphide compounds will be oxidized to sulphates, lowering the pH and mobilizing metals such as iron and aluminium.
The Ramsar Convention was originally agreed in 1975 to stem the progressive encroachment on, and loss of, wetlands. In 1993, there were 77 parties to the Convention from regions throughout the world.
Systematic drainage of the Mesopotamian Marshes is well underway by the Government of Iraq, allegedly to crush the resistance of dissidents taking refuge there. The wetlands lie between the Tigris and Euphrates Rivers in lower Iraq and constitute of the the most important wintering areas in western Eurasia for migratory waterbirds. Iraq is not a signatory to the Ramsar convention and there is no national conservation strategy or legal protection for any part of the marshes. There are also reports that toxic chemical such as Indolin are purposely being poured into the waters, killing turtles and fish. Marsh Arabs, or Ma'dan, have lived in the marshes for at least 5,000 years. In addition to desiccation of the marshes (already initiated upstream by the construction of the Tabqa dam in Syria and the Ataturk dam in Turkey) and poisoning of the marshes, their villages are under intensive artillery bombardment.
A survey revealed that 86,868 hectares of lowland peat soils remained in Britain in 1991. In 1993 it was estimated that the maximum area of natural, undamaged lowland raised bogs in the UK is less than 6,200 hectares (6% of the area of "virgin" raised bog). That was much less than the minimum protection threshold of 10,000 hectares.
Because the importance of wetlands was poorly understood in the past, over half of the wetlands in the United States have been lost since the time of European settlement. In some states and many watersheds, less than 10 percent of the original acreage of wetlands remains. Although the rate of loss has been dramatically reduced in recent years, the United States continues to sustain a net loss of approximately 100,000 acres of wetlands every year.
Vast swamp areas on Borneo, in which can be found orang-utans, bears, deer, wild pigs and several species of rare birds, became threatened after the Indonesian government decided to farm about one million hectares of peatland in 1995.
African wetlands have a rich biological diversity, with many endemic and rare plant species as well as wildlife such as migratory birds. Wetlands are found in most African countries, the largest are the Okavango Delta, the Sudd in the Upper Nile, the Lake Victoria and Chad basins, and the floodplains and deltas of the Congo, Niger and Zambezi rivers. Despite being among the most biologically-productive ecosystems in Africa, wetlands are often regarded locally either as wasteland, habitats for pests and threats to public health or as potential areas for agriculture. As a result many wetlands are being lost. During 1970's and 1980's for example, Niger lost more than 80 per cent of its freshwater wetlands. Coastal wetlands in Egypt and Tunisia and freshwater wetlands in the Sudan are also under increasing threat.