Threats to wetlands

Half of the world's wetlands have disappeared since 1900. Development and conversion continue to pose major threats to wetlands, despite their value and importance.

Tourist resort on a very fertile swamp. Fethiyé, Turkey  rel=
A tourist resort built on a very fertile swamp in Fethiyé, Turkey.
© WWF-Canon / Michel GUNTHER

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Wetlands at risk

Conversion of wetlands for commercial development, drainage schemes, extraction of minerals and peat, overfishing, tourism, siltation, pesticide discharges from intensive agriculture, toxic pollutants from industrial waste, and the construction of dams and dikes, often in an attempt at flood protection, are major threats to wetlands everywhere.
 

Industrial threats

A major threat is the draining of wetlands for commercial development, including tourism facilities, or agricultural land. In addition, unwise use of freshwater to feed these developments poses a further threat. In all too many places, the amount of water being taken from nature's underground aquifer is far outstripping its ability to replenish itself. The result is that as the water level drops, millions of trees and plants are dying because they are deprived of their life-sustaining supplies.

Hundreds of thousands of hectares of wetlands have been drained for agriculture. Globally, agriculture accounts for 65% of the total water withdrawal on Earth. Agriculture and other industries such as paper making are often very wasteful and inefficient with water.
 

Invasive species

Alien invasive species have had severe impacts on local aquatic flora and fauna, and can upset the natural balance of an ecosytem. For example, the introduction of Nile perch to Lake Victoria has pushed many of the lake's native cichlid species to extinction.
 

Pollution

Pollution in wetlands is a growing concern, affecting drinking water sources  and biological diversity. Drainage and run-off from fertilized crops and pesticides used in industry introduce nitrogen and phosphorous nutrients and other toxins like mercury to water sources. These chemicals can affect the health and reproduction of species, posing a serious threat to biological diversity.
 

Climate change

Climate change is also taking its toll. Increases in temperature are causing polar ice to melt and sea levels to rise. This in turn is leading to shallow wetlands being swamped and some species of mangrove trees being submerged and drowned.

Yet at the same time, other wetlands - estuaries, floodplains, and marshes - are being destroyed through drought.
 

Dams

Worldwide there are now over 40,000 dams which alter the natural flow of water and impact on existing ecosystems. Whilst there is much debate about the need for dams to be built, WWF argues that development should be as sustainable as possible to ensure minimum negative impact on biodiversity.

 
 / ©: WWF-Canon / R.LEGUEN
Dried-up brackish swamp, Camargue, France
© WWF-Canon / R.LEGUEN Dried-up brackish swamp, Camargue, France
 / ©: Michel GUNTHER / WWF-Canon
Dead trees drowned by Itaipu lake created by the Itaipu dam in the Atlantic rainforest. Brazil - Paraguay
© Michel GUNTHER / WWF-Canon

Mai Po Marshes

Mai Po Marshes, Ramsar site, Hong Kong, China. / ©: WWF-Canon / Mauri RAUTKARI
Mai Po Marshes, Ramsar site, Hong Kong, China.
© WWF-Canon / Mauri RAUTKARI
The designation in 1995 of Hong Kong's Mai Po Marshes as a wetland of international importance under the Ramsar Convention could not come a moment too soon.

Under constant threat from housing and land development, a myriad of infilling schemes, pollution from sewage, new industry, and even livestock waste, the marshes will now be the focus of international attention.

Already, a Sino-Hong Kong environmental liaison group is studying ways to improve the management of the marshes, and a joint water quality research project is under way. This may, however, be an example of ‘too little, too late’.

Mai Po is a startling reflection of the degradation suffered by wetlands the world over.

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Did you know?

    • In the Philippines, 80% of coastal wetlands have been drained, degraded, or destroyed in just 30 years.
    • Globally, agriculture accounts for 65% of the total water withdrawal on Earth.
  •  / ©: Ramsar

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