• Today, scientists believe that nearly 400 cichlid species are on the brink of extinction.
• The proliferation of water hyacinth and other aquatic plants, the abundance of green algae is incontrovertible evidence of a lake in deep ecological decline.
Discovered in 1858, Lake Victoria is Africa’s largest lake and the world’s second-largest freshwater lake by surface area.
The surface area of the lake is estimated at 68,800 square kilometers, which is 1.3 times larger than the combined landmass of Burundi and Rwanda.
The upland drainage basin covers Burundi, Kenya, Rwanda, Tanzania and Uganda. Nothing is more East African than Lake Victoria. The drainage basin of Lake Victoria, which is the total land area drained by the 23 rivers and streams that flow into the lake is about 194,200 square kilometers.
The combined size of the lake’s surface area and its drainage basin is about 45 per cent of Kenya’s territory. The combined population of the Lake Victoria basin is about 40 million, makingHence, this one the most densely populated regions of East Africa with an average population density of 205,000 persons per square kilometer. Counties like Kisii, Kakamega, for example have population densities above 1,000 persons per square kilometer.
The lake basin is estimated to be 400,000 years old. Three major dry periods have been recorded and the lake as we know it today arose from a dry landscape less than 15,000 years ago. Lake Victoria, also the source of the River Nile is the aquatic analogue of the tropical rainforest, vastly endowed with diverse species and ecosystems.
Among geneticists and ecologists, Lake Victoria is best known as the home of about 400 species of cichlids, evolved over just 15,000 years. This represents the most rapid and extensive evolutionary radiation of vertebrates anywhere on the planet.
Today, scientists believe that nearly 400 cichlid species are on the brink of extinction. The lake is hyper-rich with nutrients, which is the clearest sign of catastrophic ecological collapse. The proliferation of water hyacinth and other aquatic plants, the abundance of green algae is incontrovertible evidence of a lake in deep ecological decline. Moreover, the hitherto rich and diverse fisheries are now dominated by just three species; Rastrineobola (Omena), Nile perch and Tilapia.
What caused the dramatic shift in the lake ecosystem and when did it begin? The rapid increase in population, intensification of agricultural production and a surge in urbanisation in the Lake Victoria basis has exacerbated eutrophication, especially in the last three decades.
Evidence from lake sediment cores reveals that eutrophic changes in the lake began in the 1930s with a surge in population and intensified agricultural activity. The explosion of the Nile perch, the eruption of water hyacinth and algal blooms have contributed immensely to the decimation of cichlid species.
The ecological catastrophe in Lake Victoria has been long in the making. The solutions will be neither quick nor easy. We must start with land use and land management; control soil erosion, and halt the flow of nitrogen and phosphorus into our rivers. Moreover, we must manage the flow of municipal waste into the water system and step up the mechanical removal of aquatic weeds.
Nothing is more East African, we must all rise and save Lake Victoria!
Alex O. Awiti is Vice Provost at Aga Khan University. The views expressed are the writer’s