Recovery of cichlid species in Lake Victoria: an examination of factors leading to differential extinction

Publication Type:Journal Article
Year of Publication:2000
Authors:F. Witte, Msuku, B. S. , Wanink, J. H. , Seehausen, O. , Katunzi, E. F. B. , Goudswaard, P. C. , Goldschmidt, T.
Journal:Reviews in Fish Biology and Fisheries
Volume:10
Pagination:233-241
Accession Number:5139739
Keywords:Africa, Victoria L., Article Geographic, Article Subject Terms: Extinction, Article Taxonomic Terms: Pisces, D 04668 Fish, Fisheries, Freshwater pollution, Inland fisheries, Lakes, Mortality causes, organisms, Pollution effects, Population status, Predation, Q1 01422 Environmental effects, Q5 01504 Effects on, Species extinction, survival, Terms: Africa, Victoria L., ZOOPLANKTON
Abstract:

More than 110 haplochromine species belonging to 12 trophic groups had been collected from the sublittoral waters in the Mwanza Gulf between 1978 and 1982. By 1987 almost 100 species had vanished and the contribution of haplochromine cichlids to the demersal ichthyomass had decreased from more than 90% to less than 1%. During the following years, few haplochromines were caught in sublittoral areas, but a slow increase of both individuals and species was observed between 1991 and 1995. Similar observations had been made in other areas of the lake after reduction of Nile perch, without specifying species or trophic groups that recovered. After 1995, the haplochromines in the Mwanza Gulf were no longer monitored systematically. However, through local fishermen and fishery researchers we heard that the amounts of haplochromines in the catches increased. Examination of several catches in 1997 and 1999 indeed revealed a substantial upheaval of two zooplanktivorous species in the sublittoral areas, whereas other species remained rare or absent. Processes involved in extinction are rarely well documented because ecological data of species in a community prior to and during the disturbance that causes extinction are often lacking. In particular for tropical ecosystems, the fish fauna of Lake Victoria offers one of the rare cases where these requirements are met. Here, we describe the resurgence of the two zooplanktivores and suggest explanations for differences in survival and extinction among closely related species.

Alternate Journal:Rev. Fish Biol. Fish.

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