The biodiversity of Lake Victoria threatened

According to a report of the International Union for Conservation of Nature (IUCN) issued at the beginning of May, this biodiversity is diminishing and the risk of extinction of various species is increasing. This risk is estimated at 76% for endemic species, including fish, molluscs, crabs, shrimps, aquatic plants, and so forth (i.e. 150 species) and at 19.7% for the entire biodiversity of the region. In addition to this observation, the report provides several directives for supporting protective measures.

We hope that it will lead to more sustainable management of the water and territory of Lake Victoria, by informing the decision-makers and managers of conservation programs” said Will Darwall, Head of the Freshwater Unit of the IUCN and co-author of the report.

The multiple causes for the degradation of the lake’s ecosystem

The first problem is pollution, both industrial and agricultural. The lake is used as a discharge for various industries, drainage (millions of litres), fish cleaning companies, and for the neighbouring populations. For example, 500 vehicles are washed daily by young men for a paltry wage and with a high risk of disease.

Another threat is overfishing, which depletes the wealth of biological resources. The introduction of non-indigenous species has also seriously affected the quality of habitats. The Nile perch was introduced into the lake in the 1950s but has turned out be a ferocious predator for the local fauna, despite its inestimable commercial value. It rapidly became the most common and most fished species. More than 200 species of fish have disappeared, a phenomenon directly attributable to the introduction of the Nile perch. And now the perch itself has become a victim of overfishing by another predator! Another example of degradation is the water hyacinth, a South American plant introduced into Lake Victoria accidentally in the 1980s. It has developed considerably to the point of covering nearly 10% of the lake’s surface and forming thick layers that reduce the availability of oxygen and nutrients.

Lastly, climate change is also a current and a future threat. The level of the lake – 80% of which is supplied by rainfall and 20% by rivers – is falling. It lowered by 1.5 meter between 2002 and 2006. This lack of water is combined with depletion due to the large volumes of sediments washed into it from land erosion, deforestation and inefficient farming methods. The water has become turbid, eutrophication is increasing and biodiversity is suffering. And the populations, too. Two million people depend on the Nile perch for their living. Fish and local plants are also important sources of food for these often-poor people.

For further information