PARENT SESSION
Oral Session #77: Aquatic Ecology: Food webs, invertebrates. Presiding: R.A. Washington-Allen.
Friday, August 10, 2001. 8:00 AM to 12:00 PM. Hall of Ideas H.

Food resource partitioning in the littoral food web of Lake Tanganyika, East Africa.

O'REILLY, CATHERINE¹, COHEN, ANDREW¹, ¹

ABSTRACT- The East African Great Lakes contain some of the worlds most diverse freshwater faunas, and various speciation mechanisms have been proposed for the development of these species flocks. Many cichlid species show divergent jaw morphologies, implying that food resource partitioning has been important in sympatric speciation. We investigated the role of food resource partitioning in the littoral food web of Lake Tanganyika, the oldest of the lakes. We found that resource partitioning existed within a feeding guild, but not necessarily at the species level. In cases when diet items were similar, differential foraging allowed for co-existence through spatial separation of feeding areas. Although benthic primary productivity rates are high relative to phytoplankton, benthic carbon supported a much smaller proportion of the food web than expected. This suggests that anthropogenic impacts to these diverse fish communities are more likely to occur through changes in habitat structure than in changes in benthic productivity, which have been documented in some areas of the lake.

KEY WORDS: stable isotopes, food webs, speciation, Lake Tanganyika