Rift Valley lakes explained

Rift Valley lakes
Location:East Africa
Type:Series of lakes
Pushpin Map:Africa

The Rift Valley lakes are a series of lakes in the East African Rift valley that runs through eastern Africa from Ethiopia in the north to Malawi in the south, and includes the African Great Lakes in the south. These include some of the world's oldest lakes, deepest lakes, largest lakes by area, and largest lakes by volume. Many are freshwater ecoregions of great biodiversity, while others are alkaline "soda lakes" supporting highly specialised organisms.

The Rift Valley lakes are well known for the evolution of at least 800 cichlid fish species that live in their waters. More species are expected to be discovered.[1]

The World Wide Fund for Nature has designated these lakes as one of its Global 200 priority ecoregions for conservation.

Geology

Lake Malawi and Lake Tanganyika have formed in the various valleys of the East African Rift zone. Lake Kivu's "still waters ... hide another face: dissolved within are billions of cubic meters of flammable methane and more still of carbon dioxide, the result of volcanic gases seeping in."[2]

Ethiopian Rift Valley lakes national park

The Ethiopian Rift Valley lakes are the northernmost of the African Rift Valley lakes. In central Ethiopia, the Main Ethiopian Rift, also known as the Great Rift Valley, splits the Ethiopian highlands into northern and southern halves, and the Ethiopian Rift Valley lakes occupy the floor of the rift valley between the two highlands. Most of the Ethiopian Rift Valley lakes do not have an outlet, and most are alkaline. Although the Ethiopian Rift Valley lakes are of great importance to Ethiopia's economy, as well as being essential to the survival of the local people, there were no intensive and extensive limnological studies undertaken of these lakes until recently.[3]

The major ones are

Lake Tana, the source of the Blue Nile, lies in the Ethiopian highlands north of the Rift Valley; however, it is not a Rift Valley lake.[4]

Eastern Rift Valley lakes

South of the Ethiopian highlands, the rift valley splits into two major troughs. The Eastern Rift is home to the Kenyan Rift Valley lakes, while most of the Central African Rift Valley lakes lie in the Western Rift. This area includes the Gregory Rift in Kenya and Tanzania.

Kenya

The Kenyan section of the Rift Valley is home to eight lakes, of which three are freshwater and the rest alkaline. Of the latter, the shallow soda lakes of the Eastern Rift Valley have crystallised salt turning the shores white and are famous for the large flocks of flamingo that feed on crustaceans.

Tanzania

All the lakes in the Tanzanian section of this group are alkaline:

Western or Albertine Rift Valley lakes

The lakes of the Western or Albertine Rift, with Lake Victoria, include the largest, deepest, and oldest of the Rift Valley Lakes. They are also referred to as the Central African lakes. Lakes Albert, Victoria, and Edward are part of the Nile River basin.

Lake Victoria (elevation 1134m (3,720feet)), with an area of 68800km2, is the largest lake in Africa. It is not in the Rift Valley, instead occupying a depression between the eastern and western rifts formed by the uplift of the rifts to either side. Lakes Victoria, Tanganyika, and Malawi are sometimes collectively known as the African Great Lakes.

The Western Rift Valley lakes are fresh water and home to an extraordinary number of species. Approximately 1,500 cichlid fish (Cichlidae) species live in the lakes. In addition to the cichlids, populations of Clariidae, Claroteidae, Mochokidae, Poeciliidae, Mastacembelidae, Centropomidae, Cyprinidae, Clupeidae and other fish families are found in these lakes. They are also important habitats for a number of amphibian species, including Amietophrynus kisoloensis, Bufo keringyagae, Cardioglossa cyaneospila, and Nectophryne batesii.

Southern Rift Valley lakes (Tanzania and Malawi)

The Southern Rift Valley lakes are like the Western Rift Valley lakes in that, with one exception, they are freshwater lakes.

Other lakes of the Great Rift Valley

External links

Notes and References

  1. Web site: https://web.archive.org/web/20041222185611/http://www.worldwildlife.org/wildworld/profiles/g200/g182.html . December 22, 2004. WWF Global 200 Ecoregions – Rift Valley Lakes (182) . www.worldwildlife.org . 16 March 2008.
  2. News: What Lies Beneath . The Economist. 2016-03-12.
  3. Web site: Tudorancea, C. & Taylor W.D. (Eds) Ethiopian Rift Valley Lakes . www.euronet.nl . 16 March 2008 . Hynes . H. B. N..
  4. Book: Smith, Anthony . Anthony Smith (producer) . The Great Rift: Africa's Changing Valley . . London . 1988 . 978-0-8069-6906-0 . registration .
  5. Plisnier P.-D., Chitamwebwa D., Mwape L., Tshibangu K., Langenberg V., Coenen E. . 1999 . Limnological annual cycle inferred from physical-chemical fluctuations at three stations of Lake Tanganyika . Hydrobiologia . 407 . 45–58 . 10.1023/A:1003762119873. 2268/294749 . 24637697 . free .
  6. Bos AR, CK Kapasa and PAM van Zwieten . 2006 . Update on the bathymetry of Lake Mweru (Zambia), with notes on water level fluctuations . African Journal of Aquatic Science . 31 . 1 . 145–150 . 10.2989/16085910609503882. 2006AfJAS..31..145B . 86387950 .

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