African wetlands are among the most biologically diverse ecosystems on the continent, covering more than 131 million hectares, according to the Senegalese-based Wetlands International Africa (WIA). Yet, despite their importance and value; wetland areas are experiencing immense pressure across the continent. Commercial development ranks as the major threat for the draining of wetlands, including for tourism facilities and agriculture, where hundreds of thousands of hectares of wetlands have been drained.
Other threats to Africa's wetlands are commercial agriculture, settlements, excessive exploitation by local communities and improperly-planned development activities. The prospect of immense profits from recently discovered oil, coal and gas deposits has also led to an increase in on-and offshore exploration and mining in sensitive ecological areas.
In Nigeria, Guinea-Bissau and Mozambique, for example, wetlands and estuaries coincide with fossil fuel deposits and related infrastructure developments. In northern Kenya, port developments in Lamu are set to take place in the West Indian Ocean Rim's most important mangrove area and fisheries breeding ground.In KwaZulu-Natal and the Eastern Cape of South Africa, heavy mineral sands are located in important dune forest ecosystems, and gas is being prospected for in the water-scarce and ecologically unique Karoo. In East Africa, oil discoveries have been made in the tropical Congo Basin rain forest and the Virunga National Park – a world heritage site and a wetland recognised under the Ramsar Convention.
The Okavango Delta in Botswana, one of Africa's most important wetlands and designated as the 1,000th world heritage site by UNESCO, has been home to many threatened species and the main water source of regional wildlife in Southern Africa. Yet it is shrinking due to drier climate, increased grazing and growing pressure from tourism.
"This delta is a true oasis in the middle of the bone-dry Kalahari Sand Basin, a rare untouched wilderness that's been preserved by decades of border and civil wars in the Angolan catchment," said National Geographic explorer Steve Boyes in an interview. "Many people along the Okavango River live like communities did some 400 years ago – and from them I think we can learn a lot about how to be better stewards of the natural world."
Boyes calculated the abundance of life in the delta: more than 530 bird species, thousands of plant species, 160 different mammals, 155 reptiles, scores of frogs and countless insects.
"Everywhere you look you find life. We surveyed bats and we found 17 species in three days. We started looking for praying mantises and found 90 different species," he said.
A recent survey by the Botswana Department of Wildlife and National Parks and the environmentalist group BirdLife Botswana concluded that that the wetland's historical zones of dense reed beds and water fig islands were largely destroyed by hydrological changes and fire. Bush fires and a high grazing pressure further reduced the natural shores of the Okavango Delta.
Studies by BirdLife Botswana also showed that the slaty egret, a vulnerable water bird living only in Southern Africa, with its main breeding grounds in the wetlands of Zambia, Mozambique and Botswana's Okavango Delta, is now estimated to have a total population of only about 4,000 birds.