Dry Sahel



ID

504

Author(s)

Ashley Brown and Michele Thieme, WWF-US, Conservation Science Program, Washington, DC, USA


Countries

Algeria
Chad
Egypt
Libya
Mali
Mauritania
Niger
Sudan
Western Sahara

Reviewer(s)

Christian Lévêque, Centre National de la Recherche Scientifique (CNRS), Paris, France


Major Habitat Type

Xeric freshwaters and endorheic (closed) basins

Description

Freshwater habitats

In lowland areas, ephemeral streams (also called oueds or ouadis), which experience sporadic flooding from rainfall upstream at higher elevation, occur across the landscape. Water is often just below the land surface and oases dot the desert where water reaches the surface. Permanent or semi-permanent pools (also called gueltas) occur along stream-beds in mountainous areas.

Justification for delineation

During the late Pleistocene three major wet periods occurred across the Sahara, resulting in a higher prevalence of water courses. Rock drawings from later than 5,000 B.C. in the central Sahara even depict hippopotamuses (Beadle 1981). In the eastern Sahara, freshwater wetlands probably occurred across an area of about 15,000 km2 between 8,800 and 4,500 BP, including the large paleo-lake, called the West Nubian Lake (Pachur & Rottinger 1997). During the last humid period (within the last 10,000 years), connections probably existed between the Chad basin and the drainages of the mountain ranges in the southern Sahara, including the Adrar des Iforas, Tassili N’Ajjer, Hoggar, Borkou-Ennedi-Tibesti and Jebel Marra (Lévêque 1990). These connections presumably facilitated exchange of freshwater faunas between the basins. Remnants of the Sudanian fauna inhabit the few remaining watercourses and oases in the Sahel ecoregion. Due to the short-term period (5-6,000 years) since their isolation, there has been little divergence of the fauna from their Sudanian stock (Lévêque 1990).  

Level of taxonomic exploration

Fair


References

  • Beadle, L. C. (1981). "The inland waters of tropical Africa" England: Longman Group Limited.
  • Dumont, H. J. (1987). "Sahara" Burgis, M. J.;Symoens, J. J. (Ed.) African wetlands and shallow water bodies ( pp. 79-153 ) Paris, France: ORSTOM.
  • Lévêque, C. (1990). "Relict tropical fish fauna in central Sahara" Ichthyological Explorations of Freshwaters 1 (1) pp. 39-48.
  • Lévêque, C. (1997). Biodiversity dynamics and conservation: The freshwater fish of tropical Africa Cambridge, UK: Cambridge University Press.
  • Pachur, H. J. and Rottinger, F. (1997). "Evidence for a large extended paleolake in the eastern Sahara as revealed by space-borne radar lab images" Remote Sensing of Environment 61 (3) pp. 437-440.
  • Shine, T., Robertson, P. and Lamarche, B. (2001). "Mauritania" L. D. C. Fishpool and M. I. Evans (Ed.) Important Bird Areas in Africa and associated islands: Priority sites for conservation ( pp. 567-581 ) Newbury and Cambridge, UK: Pisces Publications and BirdLife International (Birdlife Conservation Series No. 11).
  • Wetlands International (2002) \Ramsar Sites Database: A directory of wetlands of international importance\ "<"http://ramsar.wetlands.org/">" (2003)