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# of Endemic Species
510: Fouta - Djalon
Major Habitat Type:
Michele Thieme, WWF-US, Conservation Science Program, Washington, DC, USA
C. Lévêque, Centre National de la Recherche Scientifique (CNRS), France; Samba Diallo, Centre National des Sciences Halieutiques de Boussoura (CNSHB), Conakry, Guinea
This ecoregion is defined by the Fouta Djalon plateau and is distinguished by an endemic aquatic fauna adapted to its headwater streams. Isolation of individual rivers, stability over geologic time, and numerous waterfalls and rapids that have restricted colonization by downstream species are believed to have encouraged the evolution of a high number of species restricted to the rivers draining the plateau. The vast majority of the plateau and the lower plains of Gaoual and Koundara are within Guinea.
Main rivers or other water bodies:
The following tributaries and rivers originate in the Fouta Djalon: the Tinkisso of the Niger basin, the Bafing and Téné Rivers of the Senegal basin, the Gambia, Komba and Tominé Rivers to the west, and the Kogon, Fatala, Konkouré, Kolenté, Kaba and Mongo to the southwest. In addition to the Senegal, the Gambia, and the Konkouré, other major river systems beginning in the Fouta Djalon include the Niger and the Kobal.
Floodplains are rather rare within the ecoregion, except in the Coliba basin northwest of the Koundara prefecture. These cover an area of between 300 and 400 km2. (Matthes 1993)Matthès (1993) has described many temporary and perennial lakes and ponds throughout the Fouta Djalon. Examples are the Mouké Djigué pond in the plain of Koloun in the Gaoual Prefecture; the pond of Brouwal in the Télimélé Prefecture, and lakes Kénè, Wèdou, and Kambouwol in the Lélouma Prefecture. These sites support traditional fishing activities and animal congregations (mammals, reptiles, birds, and insects).
The area is characterized by sections of blocky, elevated plateau (about 600 – 1,500 m) separated by deep gorges through which rivers and streams descend to the coast or to feed larger rivers inland (Daget 1962). Several of the important mountainous areas within the Fouta Djalon include Mont Loura(Mali), Fello Digui (Gaoual), Fello Sounga (Gaoual), and the raised edge of the piedmont (DNE et al. 1999; Bazzo 2000). Mont Lora is the highest peak in the region (1,538 m).
Rainfall in the region ranges between 1,600 – 2,200 mm/year, with 90% of it falling in the 6-month wet season (Hughes & Hughes 1992). The rivers descend rapidly from the plateau during the wet season, but because they drain areas dominated by sandstone, granite, and dolerite formations they have low particulate sediment loads (about 21 mg/l) compared to their dissolved load (35 mg/l). The majority of the dissolved load comes from atmospheric inputs rather than rock weathering (Orange 1992).
Flooding is intense during the wet season when large amounts of rain fall in a short period of time. However, due to the great age of the plateau and its well-weathered nature, sediment load is relatively low. The aquatic organisms of the plateau are adapted to periods of intense flooding followed by months with no rain, and thus, declining water levels.
The Fouta Djalon plateau is surrounded by a zone of forest/savanna transition, but the upland areas of the plateau are dominated by submontane vegetation, including the most prevalent species, Guinea plum tree (Parinari excelsa), and Parkia biglobasa (Martin 1991; Sayer et al. 1992). There is hardly any forest on the massif apart from some small relatively well-preserved forest reserves, and a 4.5 km2 pine plantation at Dalaba (DNE et al. 1999). The aquatic vegetation is dominated mainly by Marantacea and Cyperacea. The rivers are often bordered by a forest gallery with Pandanus. Grasses bordering the rivers are dominated by Hyparrhennia, Andropogon and Pennisetum. In many areas, the remaining forests constitute patches in the headwaters, galleries along the rivers and scattered trees on the floodplains.
The ecoregion supports a moderately endemic fish fauna with several relict species. The fish fauna is dominated by fish from the Cyprinidae (minnows), Mormyridae (snoutfishes), and Alestiidae (African tetras) families.
Description of endemic fishes:
About one-quarter of the sixty described fish species in the ecoregion are endemic. Nearly all of the endemic species are cyprinids and most of these are barbs.
Other noteworthy aquatic biotic elements:
The ecoregion is very rich in aquatic invertebrates. Among aquatic plants, more than forty families have been identified along the rivers, lakes, ponds, and flood plains.This ecoregion is also home to an endemic Bromeliaceae (pineapple family), Pitcairnia feliciana,the only member of this family to live outside of the Americas.
Justification for delineation:
Several factors facilitated evolution of the endemic fish fauna: individual rivers are extremely isolated from one another by the plateau; numerous waterfalls and rapids occur along their course, providing further isolation of headwater faunas from potential downstream colonists; and the cooler conditions afforded by the higher altitude of the plateau may have offered a refuge during periods of warming and desiccation at lower elevations. Initial uplifting in the late Jurassic created the Fouta Djalon plateau. In the Miocene, tectonic movements caused further uplifting, and the plateau has been relatively stable since that time. The plateau, as part of the Guinean range, has acted as a barrier to movements of aquatic species across it. For example, there are only a few fish species that are known from both slopes of the Fouta Djalon: Amphilius rheophilus and A. platychir, as well as Barbus cadenati, B. guineensis and B. dialonensis (Lévêque 1997). In general, the fish fauna has affinities with the Upper Guinea bioregion.
Level of taxonomic exploration:
Fair. Intensified data collection is needed.
Bazzo, D. (2000) "Atlas Infogéographique de la Guinée Maritime”, Ministère de l’Agriculture et de l’Elevage et Ministère de la Pêche et l’Aquaculture". Conakry, Guinea. CNRS-IRD-CNSHB.
Daget, J. (1962). "Les poissons du Fouta Djalon et de la basse Guinée" Mém. Inst. fr. Afr. noire 65 1-210.
Dne, Pnud, et al. (1999) "Evaluation de la diversité biologique de la Guinée: Vision, buts, et objectifs de la strategie nationale pour sa conservation et son utilisation durable. PROJET / GUI/97/G32/A/1A/99 SNPA-DB". Conakry, Guinea. Ministère Mines Géologie et Environnement.
Hughes, R. H.,Hughes, J. S. (1992). "A directory of African wetlands" Gland, Switzerland, Nairobi, Kenya, and Cambridge, UK: IUCN, UNEP, and WCMC.
Lévêque, C. (1997) Biodiversity dynamics and conservation: The freshwater fish of tropical Africa. Cambridge, UK: Cambridge University Press.
Martin, Claude (1991) The rainforests of West Africa. Basel, Switzerland: Birkhäuser Verlag.
Matthes, H. (1993) "Rapport préliminaire de la mission d'évaluation de la pêche continentale et de l'aquaculture en République de Guinée". FAO/SEP.
Orange, D. (1992). "Hydroclimatology of the Fouta Djalon massif and present dynamics of an old lateritic landscape" Science Geologiques 93
Sayer, J. A., Harcourt, C. S., et al. (1992) The conservation atlas of tropical forests: Africa. London, UK: IUCN.