Upload
laureen-powers
View
219
Download
3
Tags:
Embed Size (px)
Citation preview
Lake VictoriaEast Africa
Introduce aspects of the ecology and management of Lake Victoria with special emphasis on changes in its endemic fish fauna.
Mean depth = 40mMaximum depth = 79mSurface area = 68,000 km2
Altitude = 1,134mShoreline development index = 3.7
Basin size = 263,000 km2
Population = 27.7 million
Start of the rainy season (cool/windy)
Lake Victoria – water hyacinthEichhornia crassipes
Lake Victoria – papyrus
Cyperus papyrus
Source: Bootsma and Hecky 1993
Source: Verschuren et al. 2002. History and timing of human impact on lake Victoria.Proc. Royal Society London 269: 289-294
Core taken in 1996 from a depth of 68mDiscontinuity near 25cm depth in the core represents a hiatus of ca. 40 years (stippled zone)
Note: Increasing abundance of diatoms starting in the 1960s but decrease again in the 1980s. Diatoms replace by bloom-forming cyanobacteria
Anabaena
Cyanobacteria bloom
Microcystis
Haplochromine cichlids
Lake Victoria food web prior to the introduction of the Nile perch
[Haplochromids in black]
Lake Victoria food webfollowing the introductionof the Nile perch
Witte et al. 1992
Witte et al. 1992
Goudswaard et al. 2008