Lake Victoria Under Threat
Lake Victoria, also known as Victoria Nyanza, is one of the Great Lakes of Africa. Measuring in at 68,800 square kilometers (26,560 mi²), it is the continent’s largest lake, the largest tropical lake in the world, and the second largest fresh water lake in the world in terms of surface area. But as a result of two hydroelectricity damns, its health is being threatened.
The health of the lake and its inhabitants are at not the only ones at risk, considering the peoples living on its shores who are entirely dependent on the lake for food.
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A new study conducted by Yustina Kiwango of Tanzania National Parks and Eric Wolanski of James Cook University in Australia, and published online in the Springer journal Wetlands Ecology and Management, suggests that the damns continual overuse of the lake has decreased the lakes level by at least two meters between 2000 and 2006.
Both, located at the outlet of Lake Victoria in Uganda, have been using water at a rate of 20 to 50 percent above the allowable discharge agreed by Uganda and Egypt in 1997. Subsequently, the substantial drop in water level has left the papyrus wetlands around the lake dry. This has resulted in an 80% collapse in the tilapia fisheries recruitment.
But more than an environmental loss, the tilapia loss affects the local population, to whom the tilapia is a food staple. The study suggests that, in the long term, the Nile Perch may also be affected similarly.
An added impact of the overuse of the lake is increased eutrophication – an increase in chemical nutrients – and algal blooms. When they were underwater, the papyrus wetlands acted as a buffer for the lake from excess levels of nitrogen and phosphorus. They would absorb about half of the nitrogen and a quarter of the phosphorus, which flow into the lake. With the diminished lake, the papyrus has lost this role.
In the authors’ view, “the future of Lake Victoria and its people is very closely related to the future of its papyrus wetlands.”
Springer via PhysOrg - New threat to Lake Victoria?
Photo courtesy of Robin Hutton via Flickr
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