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Ecoregion Description


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Species Richness


# of Endemic Species


Threats

548: Malebo Pool

Major Habitat Type:

tropical and subtropical floodplain rivers and wetland complexes

Author:

Victor Mamonekene, Institut de Développement Rural, Université Marien Ngouabi-Brazzaville, Brazzaville – CONGO

Countries:

Congo; Democratic Republic of Congo

Boundaries:

The ecoregion is defined by the extent of the Malebo Pool of the Congo River, located directly north of Kinshasa. A largely lentic-adapted fauna inhabits the pool that spans the border of the Republic of Congo and the Democratic Republic of Congo.

Drainages flowing into:

Atlantic Ocean

Main rivers or other water bodies:

A rock-sill barrier in the channel of the Congo River causes it to expand into Malebo Pool directly above Kinshasa. Malebo Pool is located between Douvre cliffs upstream and the Kintambo rapids downstream. It is about 35 km long and 25 km wide and seldom exceeds 10 m in depth. Water levels fluctuate by about 3 m within the year. Water moves quickly through the pool as it makes its way towards the ensuing rapids.

Topography:

According to the Cahen hypothesis, reported by Roberts and Stewart (1976)(Roberts and Stewart 1976), the Congo Basin is thought to have been an interior drainage throughout the Miocene and most of Pliocene, perhaps forming an interior lake. Then, in the late Pliocene or early Pleistocene, a Lower Guinean coastal river captured the Malebo Pool and the Congo Basin drained to the coast. 

Climate:

The climate near Malebo Pool belongs to the Guineo-equatorial bas-Congolais type. It is characterized by a dry season from June to September and a rainy season from October to May, although there is a break in rainfall in January and February. High levels of precipitation occur from mid-November to mid-December and from March to April. These monsoonal rains originate from the Gulf of Guinea and Benguela current. Mean annual rainfall recorded at Brazzaville (1951-1960) is 1,370 mm. Mean monthly temperature ranges from maxima of 27 to 32°C to minima of 17 to 22°C.

Freshwater habitats:

Many small islands are located within Malebo Pool; the largest is called Ile Mbamou and it divides the mainstream into two channels. Extensive palm and papyrus swamps occur along its edges and there is frequent passage of floating mats of Eichhornia (Bailey 1986). Malebo Pool experiences two flooding events due to its location at the equator and the flooding of northern and southern tributaries of the Congo River at different times of the year. The first and smaller flood occurs from April to June and the second, larger one from October to January. The average annual flow of the Congo River at Pool Malebo is 30,000 m3/s during the low water period and 60,000 m3/s during the flooding season. In 1961 and 1962, when there were heavy rains in the basin, the flow reached 80,000 m3/s.

Fish Fauna:

The freshwater fauna of Malebo Pool, particularly the fishes, is lentic adapted (Citharinus spp., Distichodus spp., Tilapia spp.), although there are some rheophilic (Nannochromis nudiceps, Steatocranus gibbiceps, S. casuarius, S. tinanti) forms from the downstream rapids (Poll 1939). With over 200 fish species documented, this ecoregion is rich in fish species. Mormyrids (over 40) are the most abundant and show the highest diversification, followed by the mochokids (about 25) and the citharinids (over 20). 

Description of endemic fishes:

Most endemic fishes are catfishes, with four endemic Amphiliidae, one Clariidae, and three Mochokidae, although several of these are known only from their type locality. Among endemic fish are the mountain catfish, Leptoglanis mandevillei, L. brieni, and L. bouilloni and an upside-down catfish, Atopochilus chabanaudi.

Other noteworthy aquatic biotic elements:

This ecoregion is thought to be rich in aquatic insects, but low in richness and endemism for other aquatic taxa. Only ten frogs and eight aquatic reptiles are known from the ecoregion. Among these are the African keeled mud turtle (Pelusios carinatus), Central African giant mud turtle (Pelusios chapini), and dwarf crocodile (Osteolaemus tetraspis).

Justification for delineation:

This ecoregion is defined by the extent of Malebo Pool directly above Kinshasa. A largely lentic-adapted freshwater fauna inhabits the pool.

Level of taxonomic exploration:

Poor. Available data on the aquatic fauna of this ecoregion are old. Poll (1939; 1959) (Poll 1959)has published on the ichthyological fauna of the Malebo Pool and Sita (1980)(Sita 1980) has made a study of the vegetation. However, since those studies, there have been few studies on the aquatic flora and fauna reported from this ecoregion.

References/sources:

Bailey, R. G. (1986)"The Zaire River system" In Davies, B.R.;Walker, K.F. (Ed.). The ecology of river systems. (pp. 201-214) Dordrecht, The Netherlands: Dr W. Junk Publishers.

Poll, M. (1939). "Les poissons du Stanley Pool" Ann. Mus. Congo Belge Terv., C. Zool., sér. I Tome IV(1) 60 pp., 36 figs.

Poll, M. (1959). "Recherches sur la faune ichthyologique de la region du Stanley Pool" Annales du Musée Royal du Congo Belize 71 75-174.

Roberts, T. R.,Stewart, D. J. (1976). "An ecological and systematic survey of fishes in the rapids of the lower Zaire or Congo River" Bulletin of the Museum of Comparative Zoology, Harvard 147 239-317.

Sita, P. (1980). "La végétation du Stanley Pool en relation avec celle des plateaux voisins" Unpublished Thesis. .

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