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# of Endemic Species
Major Habitat Type:
tropical and subtropical coastal rivers
Dalmas Oyugi, National Museum of Kenya, Nairobi, Kenya and Michele Thieme, Conservation Science Program, WWF-US, Washington, DC, USA
Julius Sarmett, Pangani Basin Water Office, Ministry of Water and Livestock Development, Hale-Tanga, Tanzania
This ecoregion primarily covers the Pangani River Basin, which drains Mounts Meru and Kilimanjaro, and the North and South Pare and West Usambara Mountains. Several small coastal basins flowing into the Indian Ocean are also found within this ecoregion, in particular the rivers draining the East Usambara Mountains to the sea at Tanga. All together the ecoregion extends from just north of the Tanzania/Kenya border and then south of the mouth of the Pangani River.
Main rivers or other water bodies:
The catchment of the Pangani River covers about 42,000 km2 and comprises most of the ecoregion. The river flows southeasterly from the slopes of Mounts Meru and Kilimanjaro, and the North and South Pare and West Usambara Mountain blocks of the Eastern Arc Mountainsbefore draining into the Indian Ocean at Pangani (Dadzie et al. 1988). Major tributaries of the Pangani include the Ruvu, Kiluletwa, and Mkomazi Rivers. Lake Jipe is a shallow lake located on the Tanzania-Kenya border at 37° 40\' E, 3° 40\' S (to the east of Pare Mountains in Tanzania). It is 19 km long, 2 km wide, and only a few meters deep (Dadzie et al. 1988). It is fed by the River Lumi through a swamp at the north, with the water originating on Mt. Kilimanjaro and the Pare Mountains. Water leaves the lake through the Ruvu River at its northwestern end. A second lake, Chala, lies in a crater 19 km north of Lake Jipe and on the flank of Mount Kilmanjaro.It has steep rocky shores and deep waters. The Kikuletwa River begins on Mount Meru in the north-west and joins with streams from Mount Kilimanjaro before connecting with the Ruvu and becoming the Pangani (Baker & Baker 2001). The Pangani River is dotted with some small cataracts, the most outstanding of which is Soni Falls.
The Umba, Sigi (Tanga), Mkulumuzi, and Msangazi Rivers also drain this ecoregion into the Indian Ocean, primarily flowing from the East and West Usambara Mountains. These catchments are also included administratively within the Pangani Basin, such that its administrative area is 56,300 km2. The Umba eventually reaches the Indian Ocean at the town of Vanga in Kenya and the Sigi flows into the sea north of the town of Tanga in Tanzania. Swamps such as those above the Kalimawe Dam also occur in the ecoregion.
Rainfall varies substantially within the ecoregion. The lowlands receive an average of only about 500 mm of precipitation a year. The slopes of the mountains receive between 1200-2000 mm/year of rain, and at thehighest elevations of Meru and Kilimanjaro precipitation declines to a scanty 200 mm/year (as snow) (Hughes & Hughes 1992). Rainfall is strongly seasonal with a long rainy season from March to May when the Inter-Tropical Convergence Zone (ITCZ) passes northwards and a short rainy season between November and December with the passage of the ITCZ southwards. The dry season lasts from July to October, although there can be showers in coastal areas and on the mountains during this period, and mist precipitation forms from clouds within the mountain forests.
The terrestrial vegetation in this ecoregion is a mosaic of different types depending on altitude and availability of water. Vegetation types include alpine deserts and montane moorlands on the high mountains, montane and sub-montane forest, lowland coastal dry forest, coastal scrub, Acacia and Brachystegia woodland, riparian and swamp forests, floodplain vegetation, and mangrove forests (Hughes & Hughes 1992; Burgess & Clarke 2000). Though many plant species are endemic to the forests embedded within this ecoregion, the swamps and riparian forests are generally dominated by widespread species (e.g., Cyperus papyrus, Milicia excelsa, Antiaris toxicaria, Phragmites spp., and Ficus spp.) (Burgess & Clarke 2000). Grasses such as Echinochloa pyramidalis, Cynodon dactylon, and Oryza spp. dominate many of the floodplains of the ecoregion. Dry woodland composed of Acacia and Combretum also grows on the floodplain of the Pangani. Mangrove forests line river mouths throughout the ecoregion (Hughes & Hughes 1992; Kemp et al. 2000).
A relatively depauperate yet distinctive freshwater fish fauna inhabits this ecoregion. About one-third of the approximately thirty-five known freshwater fish species are endemic. Although Garra dembeensis is not endemic to the ecoregion, the Pangani River is the southern limit of its distribution. Cyprinids are the best-represented element of the fish fauna, although cichlids, anguillids, rivulines, mochokids, and other families are also present. About 15 species of fish occur in Lake Jipe, including the endemic O. jipe. Other species reported from Jipe include Rhabdalestes tangensis, Barbus paludinosus, Aplocheilichthys spp., Haplochromis spp., Astatotilapia bloyeti, and Clarias gariepinus. Cooler water temperatures limit the distribution of some species to higher altitudes within the ecoregion.
Description of endemic fishes:
Endemic species include Barbus venustus, Rhabdalestes tangensis, Ctenochromis pectoralis, Oreochromis hunteri, O. jipe and O. pangani. O. hunteri is restricted to Lake Chala; the juveniles of this species feed on algae and debris between boulders and occur together with crabs like Potamon platycentron (Lowe 1955).
Other noteworthy aquatic biotic elements:
A rich aquatic-associated amphibian fauna is known from this ecoregion, with several species endemic to the montane regions. For example, Hyperolius tanneri is known only from a swamp at 1,410 m asl in the western Usambaras; Phrynobatrachus keniensis occurs in upland meadows of Kenya and Mount Meru; and Parhoplophryne usambarica and Phrynobatrachus krefftii are restricted to the Usambara Mountains.Crustaceans like Macrobrachium idyella and M. rude have also been reported to occur in the Pangani River basin.
The coastal portion of the ecoregion contains parts of two Endemic Bird Areas (Coastal Forests and Eastern Arc Mountains) (Stattersfield et al. 1998), but the endemic and restricted range bird species are confined to forests or coastal woodland habitats and none are associated with wetland habitats. A number of wetland Important Bird Areas do, however, occur within the ecoregion, for example, the Nyumba ya Mungu Reservoir, located on the Pangani River downstream of the confluence of the Ruvu and Kikuletwa Rivers. This sitehosts significant congregations of wetland birds, including the largest known colony of Ardea cinerea from East Africa and significant numbers of Egretta ardesiaca, Dendrocygna bicolor, Charadrius pecuarius, Sterna nilotica, Chlidonias hybridus, and Rynchops flavirostris (Baker & Baker 2001). Lake Jipe in Kenya also supports a diverse assemblage of wetland birds (Bennun & Njoroge 2001).
Justification for delineation:
This ecoregion encompasses the Pangani, Umba, Sigi (Tanga), Mkulumuzi, and Msangazi river basins and is characterized by a fish fauna with about thirty percent endemism. This ecoregion is part of the Eastern and Coastal bioregion, whose fish fauna likely arrived within the last 12,000 years, since the last interpluvial (Roberts 1975).
Level of taxonomic exploration:
Poor. Apart from the works of Lonnberg (1910), Lowe (1955), Bailey (1966; 1969), Dadzie et al. (1988), and Eccless (1992), the freshwater systems of this ecoregion are little studied. However, Seegers (pers. comm.) is currently preparing a book on the fishes of the Pangani River. Despite Lowe’s 1955 recommendation to carry out a comprehensive taxonomic review of the native fauna before the proliferation of alien species, little work has been done and the taxonomy is now much more complicated. For instance, Lowe (1955) associated the four spined tilapiines with those of Lake Victoria, yet Bailey (1966) deemed them to be exceptionally distinct. There is therefore a need not only to unravel the tilapiine taxonomic disparities, but also to document the aquatic diversity of the ecoregion by completing comprehensive taxonomic as well as ecological studies.
Bailey, R. G. (1966). "The dam fisheries of Tanzania" East Africa Agricultural and Forestry Journal 32(1) 1-15.
Bailey, R. G. (1969). "The non-cichlid fishes of the eastward flowing rivers of Tanzania, East Africa" Revue De Zoologie Africaine 80 171-199.
Baker, N. E.,Baker, E. M. (2001)"Tanzania" In Fishpool, L.D.C.;Evans, M.I. (Ed.). Important bird areas in Africa and associated islands: Priority sites for conservation. (pp. 897-945) Newbury and Cambridge, UK: Pisces Publications and BirdLife International (Birdlife Conservation Series No. 11).
Bennun, L.,Njoroge, P. (2001)"Kenya" In Fishpool, L.D.C.;Evans, M.I. (Ed.). Important bird areas in Africa and associated islands: Priority sites for conservation. (pp. 411-464) Newbury and Cambridge, UK: Pisces Publications and Birdlife International.
Burgess, Neil D.,Clarke, G. Philip (2000) Coastal forests of eastern Africa, IUCN Forest Conservation Programme. Gland, Switzerland: IUCN.
Dadzie, S., Haller, R. D., et al. (1988). "A note on the fishes of Lake Jipe and Lake Chale on the Kenya-Tanzanian Border" Journal of East Africa Natural History Society and National Museums of Kenya 192 46-52.
Eccles, D. H. (1992) A field guide to the freshwater fishes of Tanzania. Italy: FAO.
Hughes, R. H.,Hughes, J. S. (1992). "A directory of African wetlands" Gland, Switzerland, Nairobi, Kenya, and Cambridge, UK: IUCN, UNEP, and WCMC.
Kemp, J., Hatton, J. C., et al. (2000). "East African marine ecoregion: Reconnaissance synthesis report" Tanzania: WWF.
Lonnberg, E. (1910)"Fishes" In Sjöstedt, Y. (Ed.). Wissenschaftliche Ergebnisse der schwedischen zoologischen Expedition nach dem Kilimanjaro, dem Meru und den umgebenden Massaisteppen Deutsch-Ostafikas 1905-1906.. (pp. 1-8) Stokholm, Sweden: P. Palmquist Aktiebolag.
Lowe, R. H. (1955). "New species of tilapia (Pisces, Cichlidae) from Lake Jipe and the Pangani River, East Africa" The British Museums of Natural History 2(12) 350-368.
Roberts, T. R. (1975). "Geographical distribution of African freshwater fishes" Zool. J. Linn. Soc. 57 249-319.
Stattersfield, A. J., Crosby, M. J., et al. (1998). "Endemic bird areas of the world: Priorities for biodiversity conservation" Cambridge, UK: BirdLife International.