Lake Ejagham

Lake Ejagham
Coordinates 5°45′N 8°59′E / 5.750°N 8.983°E / 5.750; 8.983Coordinates: 5°45′N 8°59′E / 5.750°N 8.983°E / 5.750; 8.983
Type Solution basin
Primary outflows Munaya River (part of the Cross River system)
Basin countries Cameroon
Max. length Approximately 1,050 metres (3,440 ft)[1]
Max. width Approximately 700 metres (2,300 ft)[1]
Surface area 0.49 square kilometres (0.19 sq mi)[2]
Max. depth Approximately 18 metres (59 ft)[1]

Lake Ejagham is a small lake near Eyumodjock in the Southwest Region of Cameroon. Unlike many other lakes in the region, it is not a volcanic lake, but is likely a solution basin formed by groundwater during the last Ice Age.[1] This highly isolated lake is roughly oval in shape, lacks an inflow, but has an outflow into the Munaya River (part of the Cross River system).[1][3] The outflow is impassable to most fishes because of a waterfall.[1]

Despite its very small size, it supports 7 endemic species of tilapiine cichlid fishes (Coptodon deckerti, C. ejagham, C. fusiforme, C. nigrans, Sarotherodon lamprechti, and S. knauerae). Of these, 6 were only scientifically described in 2010 and 2011, and have therefore not been rated by the IUCN, but they likely face the same threats as C. deckerti (the single older species that has been rated by the IUCN).[2][4][5] C. deckerti is considered critically endangered due to pollution and sedimentation from human activities, and could also be threatened by large emissions of carbon dioxide (CO2) from the lake's bottom (compare Lake Nyos).[5] A species of catfish from the genus Parauchenoglanis has been introduced to the lake, and this probably presents a serious threat to the endemic cichlids.[2]

See also

References

  1. 1 2 3 4 5 6 Freshwater Ecoregions of the World (2008). Western Equatorial Crater Lakes.
  2. 1 2 3 Dunz, A. R., & Schliewen, U. K. (2010). Description of a Tilapia (Coptodon) species flock of Lake Ejagham (Cameroon), including a redescription of Tilapia deckerti Thys van den Audenaerde, 1967. Spixiana, 33(2): 251-280
  3. ↑ Schliewen, U.K., Tautz, D., and Pääbo, S. (1994). Sympatric speciation suggested by monophyly of crater lake cichlids. Nature 368(6472): 629-632.
  4. ↑ Neumann, D., Stiassny, M. L. J, & Schliewen, U. K. (2011). Two new sympatric Sarotherodon species (Pisces: Cichlidae) endemic to Lake Ejagham, Cameroon, west-central Africa, with comments on the Sarotherodon galilaeus species complex. Zootaxa 2765: 1–20
  5. 1 2 Moelants, T. (2009). "Tilapia deckerti". IUCN Red List of Threatened Species. Version 2010.4. International Union for Conservation of Nature. Retrieved 29 April 2011.


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