Raised temperatures due to climate change have been found to reduce the productivity of plants in the depths of Lake Tanganyika in East Africa.
Piet Verburg from the University of Waterloo, Canada and colleagues analysed records from the past century. Over this period they found a decline in 'vertical mixing', namely the volume of nutrient-rich water from the depths of the lake mixing its way into shallower, warmer layers.
Combined with fewer nutrients in shallower areas and less oxygen penetration, this has led to changes in the lake ecosystem. For example, the number of phytoplankton has decreased.
If global warming continues, there will be further reductions in the plant productivity in deep tropical lakes, the authors warn in this week's Science Express.
Reference: Science Express 26 June 2003