Ecoregion Description

541: Albertine Highlands

Major Habitat Type:

montane freshwaters

Author:

Ashley Brown and Robin Abell, Conservation Science Program, WWF-US, Washington, DC, USA

Reviewers:

Marc Languy, WWF Eastern Africa Regional Program Office, Nairobi, Kenya; Lauren Chapman, University of Florida, Gainesville, FL, USA

Countries:

Democratic Republic of Congo

Boundaries:

The Albertine Highlands ecoregion is defined by the basins of the high-elevation rivers and streams that drain to the Lualaba River in the far eastern part of the Congo Basin. Whereas the Albertine Highlands topographic feature extends across the Democratic Republic of Congo, Uganda, Rwanda, Burundi, and Tanzania, this ecoregion is located entirely within eastern DRC. 

Main rivers or other water bodies:

The Lualaba’s eastern tributaries, which drain the western slopes of the Albertine Highlands, comprise the primary aquatic habitats of this ecoregion. Moving from south to north, these tributaries include the Luama, Elila, Ulinda, and Lowa Rivers, as well as the Lugula (tributary of the Ulindi) and the Oso (tributary of the Lowa). 

Topography:

Maximum elevation in the ecoregion is above 3,000 m asl for some eastern summits (e.g., Mount Kahuzi and Mohi (Itombwe)), which give way to the west to elevated plateaus at about 1,500 to 2,000 m asl (Hughes & Hughes 1992). After passing through the numerous wetlands of these plateaus, the rivers descend sharply to about 800 to 1,000 m asl, where the land levels off again in the middle and west of the ecoregion. A particularly extensive floodplain occurs along the banks of the Luama River for about 130 km, where the river flows through a relatively low valley and drains a swamp about 600 km² in extent (Hughes & Hughes 1992). 

Climate:

The climate in this ecoregion is tropical and wet. Mean annual rainfall is greatest in the higher altitudes. Average precipitation grades from over 2,200 mm per year in the center and west, at elevations of 1,000 to 1,300 m asl, to over 2,800 mm in eastern slopes above 1,800 m asl. Precipitation decreases with distance from the equator. Mean annual temperature is about 24^o C in the ecoregion. The mean daily maximum is about 30 ^oC and the mean daily minimum is 12 to 15^o C (Hughes & Hughes 1992). 

Freshwater habitats:

On their westward course, the headwater streams flow from the summits of the Albertine Highlands through savanna plateaus, where swamps and wetlands surround them. In the large swamps that line streams on the savanna plateaus, Typha domingensis and Cyperus latifolius dominate. Cyperus latifolius sometimes forms pure stands and covers large areas. Abundant wetlands along many of the rivers provide habitat for important waterbird populations.

Terrestrial Habitats:

Vegetation varies across the ecoregion with elevation. Wet rainforest and semi-deciduous forest grow below the plateaus (elevation between 1,500-2,000 m asl), whereas the vegetation is primarily woody savanna at higher elevations on the plateaus (Hughes & Hughes 1992). Miscanthidium violaceum, Scleria sp., and Nymphaea mildbraedii grow away from the plateau streams, and on the swamp edges a woody canopy about three meters in height is composed of Hypericum lanceolatum, Maytenus acuminatus, and Myrica kandtiana. At lower altitudes, Uapaca guineensis, Ficus mucuso, Irvingia smithii, Klainedoxa sp., and Mitragyna stipulosa dominate the riverside forest. Below 1,000 m, Gilbertiodendron dewevrei and Staudtia stipitata comprise gallery forests and Mitragyna stipulosa grows in semi-permanent swamp areas.  Monospecific stands of Michelsonia microphylla grow near the equator (Hughes & Hughes 1992).

Fish Fauna:

The aquatic fauna of this ecoregion is incompletely known; data are particularly patchy for fishes, reptiles, and aquatic invertebrates. Fish richness appears to be low, with only 16 described species (G. Teugels, personal communication). However, the waters of this ecoregion are poorly sampled and further investigation will probably reveal multiple new species. 

Other noteworthy fishes:

Interesting fish include Chiloglanis and Amphilius species possessing elaborate sucker-like mouths that allow them to cling to substrates and likely facilitate feeding on the vegetation growing on rocks (Welcomme & De Mérona 1988). Also of interest is Kneria wittei, which is found in streams up to 1,800 m in elevation.

Other noteworthy aquatic biotic elements:

Virunga National Park hosts several migratory bird species that use the area as a feeding and wintering ground, and large terrestrial mammals often congregate along rivers in the park (Wetlands International 2002). Two smaller, range-restricted mammals live in the waters of the Albertine Highlands ecoregion. The semiaquatic and endangered Ruwenzori otter shrew (Micropotamogale ruwenzorii) inhabits the slopes of the Ruwenzoris in the northeast of this ecoregion, in addition to the Lake Victoria ecoregion [857] (Kamdem-Toham et al. 2003). The aquatic genet (Osbornictis piscivora), endemic to the Congo basin, is largely restricted to the eastern part of the basin and is most commonly found in shallow headwater streams running through limbali forest.

The ecoregion hosts a highly endemic and rich aquatic frog fauna, in addition to several widespread reptiles. There are 53 known species of frog, and twenty-two of them are endemic. Many of the endemics, like the rare Ruwenzori river frog (Afrana ruwenzorica) and Albertine Rift reed frog (Hyperolius alticola), are from the Ranidae and Hyperoliidae families. Crocodylus niloticus, Pelusios gabonensis, and Pelomedusa subrufa occur here; researchers may discover other aquatic reptiles with further investigations.

Distributional data on aquatic macro-invertebrate assemblages in this ecoregion are largely unavailable, though some taxa have been relatively well-studied. For example, four species of freshwater molluscs inhabit the ecoregion, including the endemic snail, Tomichia hendrickxi. This species has been found in association with the macrophyte Lemna in thermal ponds with temperatures of about 35° C to 40° C. The related Tomichia kivuensis is associated with habitats containing fast currents, gravel bottoms, and aquatic plants (Brown 1994). 

Justification for delineation:

This ecoregion is defined by the upper basins of the high-elevation rivers that drain to the Lualaba River in the east of the Congo Basin. Although the fauna is incompletely known, it is thought that this area may have served as an important refuge zone for aquatic species during dry periods (Lévêque 1997). 

Level of taxonomic exploration:

Poor

References/sources:

Brown, D. S. (1991). "Freshwater snails of São Tomé, with special reference to Bulinus forskalii (Ehrenberg), host of Schistosoma intercalatum" Hydrobiologia 209 141-153.

Brown, David (1994). "Freshwater snails of Africa and their medical importance" London, UK: Taylor & Francis.

Hughes, R. H.,Hughes, J. S. (1992). "A directory of African wetlands" Gland, Switzerland, Nairobi, Kenya, and Cambridge, UK: IUCN, UNEP, and WCMC.

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.

Welcomme, R. L.,De Mérona, B. (1988) Lévêque, C.;Bruton, M.;Ssentongo, G. (Ed.). Fish communities of rivers. (pp. 251-276) Paris, France: ORSTOM.

Wetlands, International (2002) "Ramsar Sites Database: A directory of wetlands of international importance" <http://www.wetlands.org/RDB/Ramsar_Dir/_COUNTRIES.htm>(2003)