Biogeography and species diversity of diatoms in the Northern basin of Lake Tanganyika

Abstract

Abstract The geographical distribution and diversity of the diatoms in the northern basin of Lake Tanganyika (historically by far the most intensively studied area of the African Great Lakes concerning this group) are examined and compared with the data available for Lake Tanganyika as a whole. Most of the diatom taxa recorded in Lake Tanganyika are cosmopolitan in distribution, but c . 21% have a distribution restricted to the African continent and c . 8% are endemic to Lake Tanganyika. The lowest species diversity seen among the diatom communities examined was at the northernmost part of the northern basin. Effects of the high sedimentation rate of the River Ruzizi, and of pollution originating from urban and industrial sources, were evident in the diatom communities. A clear north-south trend of increased diatom diversity and a change in species composition was evident. These trends were particularly evident among endemic taxa, notably in members of the genus Surirella . Diatom communities, and especially their endemic components, may thus be valuable bioindicators of environmental perturbations within this and other ancient lakes.