By Laura Husband

Lake Tanganyika in East Africa is at its hottest for 1,500 years and is likely to affect the fish supply of those living in the four countries that surround it, a new study has found.

The study carried out by a team of geologists from Brown University, US took samples from the lake bed to measure its temperature.

The temperature increased rapidly in the 20th Century and today the surface temperature is a record 26 degrees Celsius. The warming has already affected the ecosystem and the number of fish.

“Our data shows a consistent relationship between the lake surface temperature and productivity including the number of fish,” said geologist and lead author of the study Jessica Tierney.

As the lake’s surface temperature continues to rise, fish productivity is expected to decline and this will affect the fishing industry in the region, explained Tierney.

Lake Tanganyika is one of the richest freshwater ecosystems in the world. The lake divides into levels naturally: the top 100 metres have most of the animal species while the water closest to the lake bed has less oxygen but more nutrients. The ecosystem relies on the two types of water mixing together.

Tierney found that as the lake warms the two levels cannot mix together. This means fish will struggle to get nutrients from the waterbed.

People throughout South-Central Africa depend on Lake Tanganyika’s fish, said geology professor Andrew Cohen.

The climate change models, if accurate, show the warming in the region will only get worse, explained geology professor James Russell.