Climate change threatens food supplies: As Lake Tanganyika warms, food-fish populations shrink.

Long-term changes in the temperature of Lake Tanganyika in East Africa could have devastating impacts on a major food source for the region. Already, fish stocks in the lake have fallen by 30% in the past 80 years while algae declined by 20%, reports a team of researchers supported by the National

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In addition to the commercially important species of fish, which supply up to 40% of the animal protein for communities bordering the lake in Tanzania, Zambia, Burundi, and the Democratic Republic of Congo, the algae and other organisms at the bottom of the food chain have also been affected by the changes. The researchers found that increasing air and water temperatures due to climate warming have decreased circulation from the deep water to the surface, thus altering the distribution of nutrients that support life in the food chain.

"Our research provides the strongest link to date between long-term changes in lake warming in the tropics, recorded by instruments, and declining productivity of the lake's ecosystem, as seen in sediment cores," says research team member Andrew Cohen of the University of Arizona.

More trouble may be ahead for the lake and the people depending on it: Experts predict a further 1.5[degrees]C rise in future air temperature.

"Given the already significant problems of malnutrition and civil conflict in central Africa, a significant decline in fishing yields resulting from climate change could lead to extremely serious consequences for the region's food supply," Cohen concludes.

Source: National Science Foundation, Office of Legislative and Public Affairs, 4201 Wilson Boulevard, Arlington, Virginia 22230. Web site www.nsf.gov.