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# of Endemic Species
533: Southern Gulf of Guinea Drainages
Major Habitat Type:
tropical and subtropical coastal rivers
Victor Mamonekene, Institut de Développement Rural, Université Marien Ngouabi-Brazzaville,
John Sullivan, Cornell University, Ithaca, NY, USA
Cameroon; Congo; Equatorial Guinea; Gabon
In the Southern Gulf of Guinea Drainages ecoregion, coastal rivers flow through rainforests on their way to the
Drainages flowing into:
Main rivers or other water bodies:
The main rivers are the lower Sanaga, Nyong, Ntem, Benito, and northern tributaries of the Ogooué (Abanga, Okano, and Ivindo).
The topography of the ecoregion is dominated by a sedimentary coastal plain that gives way to an inland plateau.
The climate of this ecoregion is tropical and humid, with a mean annual rainfall of between 1,500 and 2,700 mm. Mean annual temperature varies between 24 and 27°C. Flood regimes within the rivers of the ecoregion are bimodal with peaks in April through June and October through December.
The rivers of the ecoregion have a dense network of tributary streams. The Ivindo is a mostly rocky, deep river punctuated by rapids along its course through dense tropical forest. During peak flows, the rivers overspill their banks and flood the forest. This occurs especially at the head of the
The dominant vegetation is littoral forest near the coast and a mixed mesophilous-evergreen forest inland.
This is a very rich region with observed numbers of fish species exceeding predicted numbers for some river basins (Teugels & Guégan 1994). Over 270 fish species are known from this ecoregion, 58 of which are endemic (Teugels, personal communication). A stretch of approximately forty kilometers on the
Description of endemic fishes:
About one third of the endemic fish are from the genus Aphyosemion. There are also several endemic genera within the Mormyridae (Boulengeromyrus, Ivindomyrus), Cichlidae (Parananochromis), and Clupeidae (Thrattidion) families. The Ivindo River appears to be the center of diversity of a “riverine species flock” of mormyrid fishes of the genus Brienomyrus in which most species are at present undescribed (Sullivan et al. 2002). Twelve distinct species in this genus are recorded in and near the rapids of Loa-Loa on the
The Monts de Cristal is a small coastal mountain range in northern
Other noteworthy aquatic biotic elements:
Over 20 species of aquatic molluscs live in the ecoregion’s waters. Members of the Neritidae, Ampullariidae, Planorbidae, and other families are present. There are also high numbers of frogs with about 100 species known, including several endemic species.
Several large-bodied aquatic vertebrates, such as the West African black forest terrapin (Pelusios
Justification for delineation:
This ecoregion is defined by coastal rivers of the West Coast Equatorial bioregion (lower Sanaga, Nyong, Ntem, Benito, and northern tributaries of the Ogooué) which are characterized by similar fish species assemblages. The short stretch of falls on the
Level of taxonomic exploration:
Fair. Roman (1971)) (Roman 1971)published a book on the fishes of Rio Muni (Equatorial Guinea) and Kamdem Toham (1998) and Kamdem Toham and Teugels (1998) (Kamdem Toham 1998; Kamdem Toham and Teugels 1998)studied the fish biodiversity of the Ntem River. Other taxa are less well studied.
Kamdem Toham, A. (1998). "Fish biodiversity of the Ntem river basin (Cameroon): Taxonomy, ecology and conservation" Unpublished Thesis. Katholieke Universiteit Leuven.
Kamdem Toham, A.,Teugels, G. G. (1998). "Diversity patterns of fish assemblages in the Lower Ntem River Basin (Cameroon), with notes on potential effects of deforestation" Archiv für Hydrobiologie 141(4) 421-446.
Kamdem-Toham, A., D'Amico, J., et al. (2003) "Biological priorities for conservation in the Guinean-Congolian forest and freshwater region: Report of the Guinean-Congolian forest and freshwater region workshop, Libreville, Gabon, March 30-April 2, 2000". Libreville, Gabon. WWF.
Lévêque, C. (1997) Biodiversity dynamics and conservation: The freshwater fish of tropical Africa. Cambridge, UK: Cambridge University Press.
Roman, B. (1971). "Peces de Rio Muni, Guinea Ecuatorial (Aguas dulces y salobres)" Barcelona, Spain: Fundation la Salle de Ciencias Naturales.
Sullivan, J. P., Lavoué, S., et al. (2002). "Discovery and phylogenetic analysis of a riverine species flock of African electric fishes (Mormyridae: Teleostei)" Evolution 56 597-616.
Teugels, G. G.,Guégan, J. F. (1994). "Diversité biologique des poissons d’eaux douces de la Basse-Guinée et de l’Afrique Centrale in Biological Diversity in African Fresh-and Brackish water Fishes, Geographical reviews, Symposium PARADI" Annales du Musée royal de l’Afrique Central, Sciences Zoologiques 275 67-85.
Thys van den Audenaerde, D. F. E. (1966). "Les Tilapia (Pisces, Cichlidae) de Sud-Cameroun et du Gabon étude systematique, Annales du Musée royal de l’Afrique Central, 8o - Sciences Zoologiques, 153" Tervuren, Belgium: Musée Royal de l’Afrique Central.