Ashanti



ID

515

Author(s)

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


Countries

Ghana
Ivory Coast

Reviewer(s)

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


Major Habitat Type

Tropical and subtropical coastal rivers

Drainages flowing into

Atlantic Ocean


Main rivers to other water bodies

From west to east, the main rivers of the ecoregion are the Bia, Tano, Ankobra, and Pra (called the Ofin in its upper course). The lower course of the Tano River inundates 75 km2 of forested swamps before flowing into the Aby lagoon complex (Hughes & Hughes 1992). The Bia River also feeds into this complex. Lake Bosumtwi (38.5 km2), an endorheic crater lake created by a meteor impact approximately one million years ago, lies in the northeastern corner of the ecoregion (John 1986; Turner et al. 1996).



Description

Boundaries

This ecoregion is located in Ghana’s previously forested southwestern corner and a small portion of Côte d’Ivoire’s southeast. 

Freshwater habitats

The relatively short rivers of this ecoregion descend gradually from historically forested lowlands into coastal lagoons and swamps. 

Terrestrial habitats

Moving from north to south, semi-deciduous, moist evergreen, and wet evergreen rainforest forms the natural vegetation, but these now occur in patches due to clearance for agriculture. Along the coast, mangroves line river mouths, especially in the southwestern half of the ecoregion (Hughes & Hughes 1992; Sayer et al. 1992).

Description of endemic fishes

There are several fish with highly restricted distributions within the ecoregion. Endemic cichlids such as Chromidotilapia bosumtwensis live only in Lake Bosumtwi (FishBase 2001), while Limbochromis robertsi is only known from the Pra River. The spiny eel, Aethiomastacembelus praensis, is restricted to the upper reaches of the Pra River (Teugels et al. 1988).

Justification for delineation

This ecoregion is defined by the previously forested Ashanti region of Ghana, which probably, with the Eburneo ecoregion [514], remained during dry climatic phases and acted as an aquatic refuge (Hugueny & Lévêque 1994). The fish fauna of this ecoregion is primarily Nilo-Sudanian, with a portion of the fauna of limited distribution to the Ashanti and Eburneo [514] ecoregions. Examples of such species include Marcusenius furcidens, Citharinus eburneensis, and Synodontis bastiani.

Level of taxonomic exploration

Good


References

  • FishBase (2001) \Search FishBase\ "<"http://www.fishbase.org/search.cfm ">" (2001)
  • Hughes, R. H.;Hughes, J. S. (1992). "A directory of African wetlands" Gland, Switzerland, Nairobi, Kenya, and Cambridge, UK: IUCN, UNEP, and WCMC.
  • Hugueny, B. and Lévêque, C. (1994). "Freshwater fish zoogeography in West Africa: Faunal similarities between river basins" Environmental Biology of Fishes 39 pp. 365-380.
  • John, D. M. (1986). "The inland waters of tropical West Africa" Stuttgart, Germany: E. Schweizerbart'sche Verlagsbuchhandlung.
  • Sayer, J. A., Harcourt, C. S. and Collins, N. M. (1992). The conservation atlas of tropical forests: Africa London, UK: IUCN.
  • Teugels, G. G., Lévêque, C., Paugy, D., et al. (1988). "Etat des connaissances sur la faune ichtyologique des bassins côtieres de Côte d'Ivoire et de l’Ouest du Ghana" Revue d’Hydrobiologie Tropicale 21 pp. 221-37.
  • Turner, B. F., Gardner, L. R., Sharp, W. E., et al. (1996). "The geochemistry of Lake Bosumtwi, a hydrologically closed basin in the humid zone of tropical Ghana" Limnology and Oceanography 41 (7) pp. 1415-1424.
  • Wetlands International (2002) \Ramsar Sites Database: A directory of wetlands of international importance\ "<"http://ramsar.wetlands.org/">" (2003)