Item Details

Title: History and timing of human impact on Lake Victoria, East Africa

Date Published: January 2002
Author/s: Dirk Verschuren, Thomas C. Johnson, Hedy J. Kling, David N. Edgington, Peter R. Leavitt, Erik T. Brown, Michael R. Talbot and Robert E. Hecky
Data publication:
Funding Agency :
Copyright/patents/trade marks:
Journal Publisher: The Royal Society
Affiliation: 1Large Lakes Observatory, University of Minnesota, 10 University Drive, Duluth, MN55812, USA
2Department of Biology, Ghent University, Ledeganckstraat 35, B-9000 Gent, Belgium
3Department of Fisheries and Oceans, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6
4Center for Great Lakes Studies, University of Wisconsin, Milwaukee, WI 53201, USA
5Limnology Laboratory, Department of Biology, University of Regina, Regina, Saskatchewan, Canada S4S 0A2
6Geological Institute, University of Bergen, Allegt. 41, N-5007 Bergen, Norway
7Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
Keywords: landscape disturbance; eutrophication; fish introduction; human impact; Lake Victoria;
Nile perch


Lake Victoria, the largest tropical lake in the world, suffers from severe eutrophication and the probable
extinction of up to half of its 500+ species of endemic cichlid fishes. The continuing degradation of Lake
Victoria’s ecological functions has serious long-term consequences for the ecosystem services it provides,
and may threaten social welfare in the countries bordering its shores. Evaluation of recent ecological
changes in the context of aquatic food-web alterations, catchment disturbance and natural ecosystem
variability has been hampered by the scarcity of historical monitoring data. Here, we present highresolution
palaeolimnological data, which show that increases in phytoplankton production developed
from the 1930s onwards, which parallels human-population growth and agricultural activity in the Lake
Victoria drainage basin. Dominance of bloom-forming cyanobacteria since the late 1980s coincided with
a relative decline in diatom growth, which can be attributed to the seasonal depletion of dissolved silica
resulting from 50 years of enhanced diatom growth and burial. Eutrophication-induced loss of deep-water
oxygen started in the early 1960s, and may have contributed to the 1980s collapse of indigenous fish
stocks by eliminating suitable habitat for certain deep-water cichlids. Conservation of Lake Victoria as a
functioning ecosystem is contingent upon large-scale implementation of improved land-use practices.