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Introduction

Central and Eastern Africa are home to an incredible depth of biodiversity. This is true of both the land itself and its inland waters. The Congo River has the highest species diversity of any freshwater system in Africa, and is only behind the Amazon as far as species richness globally (Brooks, Allen, & Darwall 2011). In both Central and Eastern Africa, freshwater fishes are integral to the income and livelihood of residents. They provide direct and tangible benefits in the form of fisheries, so their conservation is in the best interest of East and Central Africans.

The Region

Central Africa is not heavily developed, though this is likely to change over the next several decades. The countries that fall within this region include Equatorial Guinea, Congo, Gabon, Democratic Republic of Congo, and parts of Angola, Zambia, Cameroon, and Central African Republic. Central Africa is a heavily forested region that includes the Congo and Lower Guinea rainforests. The Congo basin and Lower Guinean Provinces within Central Africa are home to unique diversity, ecosystems, and threats.

The Central African region is bordered to the north by more savannah regions and to the south by the Central African plateau and southern African highlands (Brooks, Allen, & Darwall 2011). The Eastern Africa area is characterized by the Central African highlands and rift valley.

Central Africa includes an equatorial zone and some tropical zones. It does not have a true dry season and receives high amounts of rainfall (between 1,500 and 2000 mm a year). The region is sparsely populated and industrialization and urbanization are strongly regionalized. Much of the land remains undeveloped, which helps to explain why the majority of freshwater fish species in the area are classified as Least Concern (62%).

The Eastern Africa Region of the FFSG includes Burundi, Kenya, Malawi, Rwanda, Tanzania, and Uganda. Like Central Africa, it is highly diverse and of great regional importance for income and livelihoods. According to the 2005 IUCN-SSC assessment, over one million people are dependent upon the fisheries from Lake Tanganyika and Lake Victoria"s fisheries provide protein for the eight million people along the lake"s shore and support over 100,000 fishermen (Darwall, Smith, Lowe, and Vié 2005). Lakes Malawi and Tanganyika are the most species rich areas in Eastern Africa when combining all freshwater species (and thought to be some of the highest of any area globally). Therefore, they are key to the future of the region"s biodiversity.

In Eastern Africa a number of sites have been identified as regionally important for species richness, species endemism, and threatened species, the main sites being the African Great Lakes, Malawi, Tanganyika and Victoria. The Rufiji, Pangani and Tana River systems were also identified as important centres for freshwater biodiversity in the region (Darwall, Smith, Lowe, and Vi√© 2005).

Freshwater Fish Species

As a response to the lack of available data on freshwater taxa in Central Africa, the IUCN Species Programme conducted a regional assessment on the status and distribution of over 2,200 taxa, including freshwater fish, from 2008 to 2011. Much of the information contained in this report is a direct result of those assessments and studies.

The channel of the Congo River and its tributaries, the Ubangi River and the Kasai River, have the highest species diversity within Central Africa. Over 858 species have been assessed in the Congo basin alone. The Central African region is home to approximately 1,207 assessed species of fish from 47 different taxonomic families, and 71% of the freshwater fish species assessed in this area are endemic to the region (Brooks, Allen, & Darwall 2011). In all likelihood the number of species is higher because taxonomic surveys are lacking and new species are continually being discovered in the region. In fact, according to the IUCN Species Programme report, “With such a renewed focus on survey work and intensified efforts to fully document the status, extent and distributional limits of Central African fish species we can reasonably anticipate the discovery of many scores, if not hundreds, of new species in the coming decade,” (Brooks, Allen, & Darwall 2011).

Several factors contribute to the particularly high species diversity, especially in the Lower Guinea and Congo provinces. The area has a dense hydrographic network, diversity of river types and habitats, and many hydrographic barriers between habitats (e.g., waterfalls and rapids) (Thieme et al. 2005; Brummett et al. 2009a). Surprisingly, the highest levels of endemic species in Central Africa are present in the main channels of the largest rivers in the Congo basin (see image below) as opposed to being found in the isolated headwaters of river basins (Stiassny et al. 2010).

CA FW Species by RL Category

Figure 1: Number of freshwater fish species in each regional Red List Category in Central African region (Brooks, Allen, & Darwall 2011).

SppDistributionCA

Figure 2: The distribution of freshwater fish species endemic to Central Africa, mapped to river sub-catchments (Brooks, Allen, & Darwall 2011).

Within Central Africa it is possible to distinguish two main “ichthyological provinces” based upon the composition and distribution of fishes: the Lower Guinean and the Congo basin Provinces (Roberts 1975; Leveque 1997). The Congo basin province is home to fewer threatened species compared to Lower Guinea, where threatened species are spread throughout. Out of the 26 species that are Critically Endangered in the Lower Guinea province, 23 come from the Western Equatorial Crater Lakes ecoregion. Twenty-one of these are lake cichlids (Stiassny et al., 1992; Schliewen et al. 1994; Schliewen 2005). This ecoregion is an area of concern due to the high concentration of the entire region"s Critically Endangered fish species. Only one species of fish, Teleogramma brichardi, is Critically Endangered in the Congo basin province.

In 2005 the IUCN/SSC Freshwater Biodiversity Assessment Programme conducted regional assessments of various freshwater taxa, including 1090 species of freshwater fish covering 41 families (Figure 3). The assessments were in part the result of the 2003 IUCN Red List data on Eastern Africa freshwater fishes. In this 2003 assessment, 100 fish species were assessed. Of those, 55% were Threatened or Extinct and 45% were Data Deficient (IUCN 2003). The extremely high level of Threatened species is in part due to bias in selecting those species already known to be threatened. The 2005 regional assessments helped to alleviate the selection bias. The results of the 2005 study presented a less bleak picture of threat statuses for Eastern African freshwater fishes. Twenty-eight percent of the total number of fish taxa assessed at the global level were classified as threatened. The main areas of threatened fishes are within Lake Victoria. Invasive species, eutrophication, and overfishing have contributed towards the threatened status.

EA FW Species RL Category

Figure 3: Number of freshwater fish species in each regional Red List Category in Eastern African region. The categories are abbreviated as: EX = Extinct; CR = Critically Endangered; VU = Vulnerable; NT = Near Threatened; LC = Least Concern; DD = Data Deficient (Darwall, Smith, Lowe, and Vié 2005).

Like Central Africa, regional endemism in Eastern Africa is very high (82%) for freshwater fishes, particularly within the Rift Valley lakes (Darwall, Smith, Lowe, and Vié 2005). This indicates a significant degree of adaptation to local environmental conditions within the region. Many of these endemics are from the family Cichlidae. As far as species distribution in Eastern Africa, the greatest concentrations of species are in the African Great Lakes, Malawi, Tanganyika, and Victoria (Darwall, Smith, Lowe, and Vié 2005).

Threats

Eastern and Central African freshwater fish species face numerous threats, including:

•Habitat loss. The greatest threat to all freshwater species in these regions comes from habitat loss due to agriculture and deforestation. Increasing population and poverty, coupled with false valuations of rainforest biodiversity have led to habitat destruction and over- exploitation of the forest resources (Stiassny 1996). Habitats are lost as land is converted for use in logging, agriculture, and even charcoal production. Loss of forest can be problematic to riverine and (especially) lake ecosystems. Both are heavily dependent on nutrients derived from surrounding forests. Forested watersheds are being lost at an annual rate of 7% in some areas, such as the Congo Basin (Revenga et al. 1998). Land is also converted to plantations in parts of the region for use on such crops as bananas, rubber, and oil palms. Slash-and-burn agriculture is common.

•Dams and infrastructure development. Dams are actually less of a threat in Central Africa than in other parts of Africa. The Lower Guinea province currently does have several dammed rivers and other dams are planned for development in the region. Dams can threaten seasonally migratory species and spawning.

•Water pollution. Pollution of freshwater in the region can come from sedimentation, mining activities, human settlement, and agricultural runoff (Brooks, Allen, & Darwall 2011; Brummett et al. 2009).

•Mining. Mining threatens freshwater fishes in thee ways: pollution, increased sedimentation, and deforestation. Gold, diamonds, and mineral ores are the targeted materials in Central and Eastern Africa regions. Diamond mining, for example, causes major habitat modification and increased sedimentation from digging up river beds and clearing of riparian vegetation (Brooks, Allen, & Darwall 2011).

•Population growth. In many parts of Africa, especially Eastern African countries the growth rate projections are much higher than the global average. This is not inherently negative; however, growing populations require more drinking water and water required for irrigation. Population is more of a driver to other threats than a threat itself.

CA_Threats

Figure 4: Percentage of fish species in Central Africa known to be affected by each threat (Brooks, Allen, & Darwall 2011).

Conservation Action

The IUCN Global Species Programme has come up with several recommendations following its assessments in 2011. They are as follows:

•Future efforts in managing inland waters must take account of the upstream and downstream connectivity in freshwater ecosystems. Environmental Impact Assessments should be utilized for future development projects in these regions, such as dam construction.

•Integrated Water Resource Management is recommended along with the initiation of additional river/lake basin authorities, and increased capacity to manage protected areas.

•Data Deficient species make up a noteworthy percentage of all species in Central Africa, particularly among endemics. Many of the regions with Data Deficient species also include relatively high numbers of threatened species. This may mean that that the Data Deficient species are in fact threatened, but have not been adequately assessed. Therefore, these regions should be identified as priorities for further monitoring and surveys (Brooks, Allen, & Darwall 2011).

•It is imperative to maintain the pristine areas of habitat in the region and to protect these areas from looming threats such as forestry, dams, and mining. Developing parks and protected areas around rivers and wetlands is essential. Particular attention should be paid to those areas with exceptionally high levels of diversity and those containing high levels of threatened species.

•Protected Areas need to be expanded to target entire water catchments, or at least the catchments for headwaters, if wetland sites are to be more effectively protected (Darwall, Smith, Lowe, and Vi√© 2005). Protected Areas would be more effective if they covered more of the fishes" habitats. In Eastern Africa, the amount to which freshwater fish habitats are protected is illustrated in Figure 5 (below).

E. Africa PAs

Figure 5: The relationship between freshwater fish distribution and Protected Areas (Darwall, Smith, Lowe, and Vié 2005).

•Further research and survey work in Eastern and Central Africa would be beneficial and help shed light on species" distributions, taxonomy, ecology, and threats.

•The use of Key Biodiversity Areas (KBAs) could serve as an effective framework methodology to help direct actions to sites for which conservation and management intervention would be most effective in meeting regional targets. KBAs focus on areas of the greatest species richness, numbers of threatened species, and regionally endemic restricted range species (Darwall, Smith, Lowe, and Vi√© 2005).

References

Brooks, E.G.E., Allen, D.J. and Darwall, W.R.T. (Compilers). 2011. The Status and Distribution of Freshwater Biodiversity in Central Africa. Gland, Switzerland and Cambridge, UK: IUCN.

Brummett, R., Tanania, C., Pandi, A., Ladel, J., Munzimi, Y., Russell, A., Stiassny, M., Thieme, M., White, S. and Davies, D. 2009a. Water resources, forests and ecosystem goods and services. In: De Wasseige, C., Devers, D., de Marcken, P., Eba"a Atyi, R., Nasi, R. and Mayaux, P. (eds.) The forests of the Congo Basin: State of the forest 2008, pp.1411–1457. Publications Office of the European Union, Luxembourg.

Darwall, W.R.T., Smith, K., Lowe, T. and Vié, J.-C. (eds.) 2005. The Status and Distribution of Freshwater Biodiversity in Eastern Africa. Occasional Paper of the IUCN Species Survival Commission 31. IUCN, Gland, Switzerland and Cambridge, UK: IUCN SSC Freshwater Biodiversity Assessment Programme.

Lévêque, C. (ed.) 1997. Biodiversity Dynamics and Conservation: the Freshwater Fish of Tropical Africa. ORSTOM, Paris.

Revenga, C., Murray, S, Abramovitz, J. and Hammond, A. 1998. Watersheds of the World: ecological value and vulnerability. World Resources Institute and Worldwatch Institute, Washington DC, USA.

Roberts, T.R. 1975. Geographical distribution of African freshwater fishes. Zoological Journal of the Linnaean Society 57: 249–319.

Stiassny, M.L.J. 1996. An overview of freshwater biodiversity: with some lessons from African fishes. Fisheries 21(9): 7–13.

Schliewen, U. 2005. Cichlid species flocks in small Cameroonian lakes. In: Freshwater ecoregions of Africa and Madagascar: a conservation assessment. Eds. Thieme, M.L., Abell, R., Stiassny,

Schliewen, U.K., Tautz, D. and Pääbo, S. 1994. Sympatric speciation suggested by monophyly of crater lake cichlids. Nature 368 (6472): 629–632.

Stiassny, M.L.J., Schliewen, U.K. and Dominey, W.J. 1992. A new species flock of cichlid fishes from Lake Bermin, Cameroon with a description of eight new species of Tilapia (Labroidei; Cichlidae). Ichthyoogical Exploration of Freshwaters 3(4): 311‚Äì346.

Stiassny, M.L.J., Revenga, C. and Comer, P. 2010. Aquatic ecosystems: diversity and dynamism. In: Fresh water: the essesence of life. Eds. Mittermeier, R.A., Farrell, T.A., Harrison, I.J., Upgren, A.J. and Brooks, T.M. pp. 93‚Äì117. CEMEX and ILCP, Arlington, Virginia, USA.

Thieme, M.L., Abell, R., Stiassny, M.L.J., Skelton, P., Lehner, B., Teugels, G.G., Dinerstein, E., Kamdem Toham, A., Burgess, N. and Olson, D. 2005. Freshwater ecoregions of Africa and Madagascar: a conservation assessment. Island Press, Washington DC, USA.