Threats to wetlands
Wetlands at risk
Industrial threatsA 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 speciesAlien 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.
PollutionPollution 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 changeClimate 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.
DamsWorldwide 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.
Mai Po Marshes
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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