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16 Dec 03

Lake Basin Management Problems in Africa: Historical and Future Perspectives

S. O. Wandiga

1. Introduction The African Great Lakes comprise a chain of fresh and alkaline water reservoirs located mainly in the Greater and Lesser Eastern and Central Rift Valley (Fig.1). Apart from Lake Chad and the man made Lake Kariba, the remaining Lakes Baringo, Malawi/Nyasa, Tanganyika, Victoria, Naivasha and Nakuru are situated in the Rift Valley and are tropical lakes. Each has its splendid and curative beauty that for aesthetic reasons alone earn them posterity (Figs. 2-7). The age of the oldest lakes range from 7 to 12 million years. Youngest, except for Lake Kariba, is about 400,000 years. Each lake has its own unique catchments basin with its own variety of endemic species. Table 1 presents unique characteristics of these lakes that focus attention to their conservation. All the lakes are used for the support of fast expanding human population. They are home to special animal and fish species. They provide water or electricity, trade and communication channels and have special economic value and resource base for the riparian communities. Figure 1. The Great Rift Valley Lakes Figure 2. Lake Victoria (Photo: M. Nakashima) Figure 3. Lake Tanganyika (Photo: S.Yamagishi) Figure 4. Lake Malawi/Nyasa (Photo: Bootsma) Figure 5. Lake Nakuru (Photo by Adams) Figure 6. Lake Kariba (Photo: N. Hata) Figure 7. Lake Chad. Source: Hutchinson and Kolawole (1987) Table 1. Unique characteristics of the lakes. On the other hand, each lake differs from the other with respect to limnology, catchments dynamics and human impacts (Hamilton, 1982). However, one thing in common to all the lakes is that they face unprecedented differentiating pressures from a variety of human related activities. The critical issues facing the lakes include rapid riparian population growth, unsustainable exploitation of fisheries and other living resources (over exploitation), pollution- microbiological and chemical, eutrophication, suspended soils arising from deforested catchments areas, fresh water shortage, global change habitat and community

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modification. The rapidly evolving ecological changes occurring in these lakes threaten their survival as sites of great human heritage and may alter permanently their ecosystem function and overall biodiversity (Hecky, 1992). The lakes have experienced rapid expansion of riparian population growth as a result of flourishing urban centres, volume of trade and commercial activities in their vicinities, easy transport and communication through them. Efforts to increase food productivity have resulted in the introduction of alien species to all of the lakes. The introduced alien species have accelerated the extinction of indigenous species in some lakes and may have altered the ecology of these lakes. Such human experimentations have had disastrous results in shallow lakes like L. Victoria, L. Chad and L. Naivasha. Industrial and commercial activities have blossomed around these lakes with the establishment of small and large industries in urban centres which today spew high loads of untreated industrial waste, sewage and solid waste into the lakes. Poor farming practices, firewood and charcoal burning activities have resulted in deforestation of the catchments. High nutrient and soil loads have entered the lakes through basins’ drainage rivers. Global climate change, high demand for irrigation waters, unpredictable weather condition extremes have potential risks for fresh water shortage, lake temperature change, silted lake shores and beds, altered ecology that have already started affecting the lakes or are foreseen in the future scenarios. Several socio-economic issues such as wide spread poverty, diseases like malaria, cholera, typhoid, tuberculosis and HIV/AID have serious implications on the riparian communities and may affect the management of the lakes. Conflicts such as between man and wild animals, between communities over the use of water, between farming, urban and indigenous communities have arisen. The basins environment does not have, if any, infrastructural development nor do the communities have resources to develop one without external assistance. Therefore, it is concluded that deterioration of the African Great Lakes has resulted from the following major causes:

• Rapid population growth of the riparian communities with concomitant rapid expansion of urban centres;

• Large demand of export markets for fisheries with no improvement of fish handling capacities and technologies;

• Lack of compliance to and enforcement of legislations governing fisheries industry and environmental pollution;

• Weak regional integration of legal, institutional and implementing mechanisms for sustainable ecosystems management

• Low level of community participation in ecosystems management due to lack of education and public awareness of issues

• Pervasive prevalence of endemic disease like malaria, HIV/AIDS, typhoid, cholera and tuberculosis that reduce productivity of people.

Several communities, national, regional, and international efforts to save these lakes have been initiated. Experiences and lessons learned from living with the people made and natural changes on the lakes, efforts to ameliorate the pressures are reviewed in this paper. 2. Background

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2.1 Description: Geographical, socio-economic, physico-chemical and environmental

characteristics of the lakes’ basins The African Great Lakes are situated in an area stretching from the Gulf of Eden covering Ethiopia, Kenya, Uganda, Republic of Congo, Rwanda, Burundi, Tanzania to the northern parts of Mozambique and Zambia (Fig.1). Some of the main lakes in the region include Victoria, Tanganyika, Malawi/Nyasa, Turkana, Albert, Edward, George, and Kivu. All are typical tropical lakes and are generally referred to as African Great Lakes eco-region (WWF SARPO, 2001). The large lakes of East African Rift Valley (Fig.1) are unique natural resources that are heavily utilised by their bordering countries for transportation, water supply, fisheries, waste disposal, recreation and tourism. Over fishing, siltation from the erosion of deforested basins, species introductions, industrial pollution, eutrophication and climate change are all contributing to a host of rapidly evolving ecological changes in the lakes’ basins that seriously threaten their ecosystem function and overall diversity (Odada, et. al. 2003a; Hecky and Bugenyi, 1992). Lakes Chad and Kariba are included in this review because the former is fast disappearing and the latter is one of the largest man made lakes. The physiographic statistics of each lake are given in Tables 2 to 10. Each lake exhibits a distinct physiographic feature that is rarely repeated except for transparency and dissolved oxygen. There is a steady decline in some of the features like transparency, dissolved oxygen, siltation and depth over time as a result of anthropogenic activities. Table 2. Physiographic statistics for Lake Victoria Table 3. Physiographic statistics for Lake Tanganyika Table 4. Physiographic statistics for Lake Malawi/Nyasa Table 5. Physiographic statistics for Lake Naivasha Table 6. Physiographic statistics for Lake Nakuru Table 7. Physiographic statistics for Lake Baringo Table 8. Physiographic statistics for Lake Chad Table 9. Physiographic statistics for Lake Kariba Table 10. Physiographic Statistics for Lake Malawi/Nyasa 2.2 Biophysical Features Fig 8 gives the Lake Victoria catchments basin. The ecology of the basin has seen rapid changes resulting from agricultural practices, thus has resulted in massive deforestation of forests originally found in the area before independence in the 1960s. Poor agricultural

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practices have resulted in increased soil erosion and particulate deposits in the lake. Massive soil erosion has been experienced in Rwanda, Burundi and Kenya. The three countries contribute most of the nutrients load deposited into the lake (Odada, et. al. 2003b). (Fig 8) Lake Victoria Catchments Basin All the African great lakes have had similar experience of rapid ecological alterations in their basins. The changes that occurred are represented by what happened in L. Nakuru. For example, Lake Nakuru in 1930 Nakuru Town was just a railway station. The forests were untouched and rangeland was unaltered (Fig. 9). However, between 1986 and 1998 as depicted in Figs. 10 and 11 considerable changes took place with he development of the town and the introduction of farming activities. In slightly over one decade, the catchments forest cover reduced to small patches (Fig. 11). Farming, illegal logging and urbanisation replaced the once thick forests. Demand for fresh water withdrawals increased and further reduced the river water volumes flowing to the lake. Lake Chad has possibly received the worst combined human and natural effects. Today, this lake that was once possibly the largest in Africa has been reduced to a pond during some seasons (Hutchinson and Kalowale, 1987). Figure 9. Lake Nakuru Catchments Basin (1930) Figure 10. Lake Nakuru Catchments Basin (1986) Figure 11. Lake Nakuru Catchments Basin Changes (1998) All the lakes are situated in valleys that are fed by rivers draining the catchments. The states of these rivers have changed with increased human population that has resulted in high farming activities and deforestation. Today these rivers have high loads of nutrients and pollutants that are drained into the lakes. For example, increased nutrient flows into Lake Victoria, coming mostly from rural areas (Verschuren, et. al., 2002) have been estimated to range between 69 x 107 kg/yr to 1.98 x 1010 kg/yr. L. Tanganyika receives 1,500 mm per thousand years in the southern basin, 500 mm per thousand years in the central basin and 4700 mm per 100 years in the northern basin, while Lake Victoria receives 2.3 mm per year of nutrient load (silt, P, N and others) (Odada, et al., 2003a; Verschuren, et. al., 2002). Most of this results from poor agricultural practices. Fertilizer use is less in the catchments basin farms compared to other basins but it may be estimated that the P and N nutrients are released mainly from soil particles washed off the upstream land by erosion, from burning wood-fuels, detergents and from human and animal waste from the areas surrounding the lake. The increased inflow of nutrients into Lake Victoria is resulting in eutrophication. Phosphorus and nitrogen concentrations have risen and algal growth has increased five-fold since the 1960s. A shift of algal flora composition towards blue-green algae is causing deoxygenation of water, health problems for humans and animals drawing water from the lake, clogging of water intake filters and increased treatment costs for urban centres. Deep water species have sharply declined and periodic upwelling of hypoxic water has caused massive fish kills (Talling, 1966, Verschuren, et al., 2002). Urbanization has led to destruction of littoral zone habitat, poorer water quality, and increased nutrient load, which in turn, has led to anoxic conditions in some areas of the lake, triggering massive indigenous fish die-offs in lakes Victoria, Naivasha, Nakuru, Baringo and Chad (Hutchinson and Kalowale, 1987; Verschuren, et. al., 2002; Oguttu-Ohwayo, 1990 and

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Witte, et. al, 1992). Some exotic species introduced into these lakes like the Nile perch may be better adapted to live in the lake as it now exists; perch have better vision at low light and do not require use of the littoral zone for cover and breeding. Haplochromines, on the other hand, have better daylight vision, and with some of the lakes now continually dusk-like, they are less able to avoid predators. In addition, Haplochromines traditionally relied on the littoral zone for breeding and for protection, since the immobile waters of the littoral zone contain less oxygen and dissuade perch from swimming there. The Haplochromines have been forced to come to the surface where they found voracious predator, the Nile perch (Verschuren, et al., 2002). The use of pesticides has intrinsic public health and environmental risks. Some pesticides are toxic and others are suspected to be carcinogenic, mutagenic and endocrine disruptors. Despite the reported rapid degradation of pesticides in tropical terrestrial, marine and freshwater (Wandiga, 2001; Aryamanya-Mugisha, 1993) aquatic environments the potential for bio-accumulation and bio-concentration of these pesticides even in the tropics (Taylor, et al, 2003 ) poses serious ecological and health concerns for the lakes. Among the sources of pollution are a number of basic industries such as breweries, tanning, fish processing, agro-processing, abattoirs and mining whose waste discharge is increasing in parts of their catchments leading to contamination of waterways by mercury (Kishimba, personal communication). Most of this results from poor sewage treatment plants. Human activities are affecting the lakes directly or indirectly. Global climate change resulting from greenhouse gases effects may have started affecting the lakes. For example the recent observation of rise in Lake Tanganyika’s water temperature has been attributed to climate change (Verburg, et. al., 2003). Similar observation has already been recorded for Lake Victoria (Bugenyi and Magumba, 1996). Lake Chad is a worst example of impact of climate change (Hutchinson and Kolawole, 1987). All the Great Lakes are affected by climate change. Table 11 gives the types of flora and fauna found in each lake. Except for the invasive species like water hyacinth and water lilies that are found in four lakes, each lake has a distinct characteristic of species. Indeed the table confirms the non-connectedness of these lakes. Their biodiversity is distinctively unique and further argues for their special treatment. Table 11. Flora (Macrophytes, Phytoplanktons) and Fauna (Fish) found in the lakes 2.3 Socio-economic issues The beginning of the decline of the Great Lakes can probably be traced to the early 1920s and 1930s, with the opening of the interior to settlement by the colonizing powers. Until then, the pressure on the Lakes was limited to that exerted by indigenous riparian communities whose population within each lake basin in the 19th and early 20th centuries varied but was small. With the establishment of urban centres around the lakes came more people to help with their construction, which was the beginning of a continuous increase in urbanization. Population increased for example around Lake Victoria at a rate of about 3.5% per year resulting in a population exceeding the carrying capacity of the land as it is today. As the population around the lakes grew, so did the fishing pressure on the native species and the farming pressure on the surrounding land. More efficient fishing techniques were introduced, and the fish caught got smaller and fewer. Demand for increased food production and the introduction of modern

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agricultural activities introduced fertilizer and pesticide runoff into the lake’s drainage rivers and directly into the lake itself (Wandiga, et. al, 2003) with serious implications for daily food intake and ecology. The lakes are economically important as sources for fish whose export has seen increased demand. The fisheries contribute directly or indirectly to the income of riparian communities with varied annual landed values in US$ millions. The catchments have seen cash crops, like horticultural produce, farming activities and together with small and medium scale industries became second income earners. Tourism and recreation facilities are well developed in most lakes environments and there is vibrant small artisanal activities to service the tourism industry. Utilization of the lake resources has made them to be designated by various governmental authorities as Development Zones. The same designating body has developed strategies to foster economic growth in the basins. For example, Lakes Victoria, Naivasha, Nakuru, Malawi, Tanganyika, Chad and Kariba have strategies for their development. Despite these efforts, the multiple activities in the lake basins have increasingly come into conflict with riparian communities due to several negative trends mentioned above and driving forces, often working in combination. Some major threats to the basin are:

• Ecological degradation e.g. pollution, land/forest degradation, biodiversity degradation, introduction of exotic species.

• High population pressure. • Wide spread poverty. • High incidence of diseases such as HIV/AIDS, malaria, bilharzia, tuberculosis,

typhoid and pneumonia • Policies, laws and regulations-scattered legislations, insufficient enforcement and un-

harmonised policies and laws governing natural resources management. 3. Management of Environment A first management issue is the stabilization of rapid riparian community growth. The basins’ urban centres have seen very rapid expansion of their dwellers who are seeking illusive jobs. The built infrastructures in these centres cannot cope with the fast population increase. As a result, almost all urban centres have no functionary public health facilities like sewer treatment plants. There are also non-existent enforcement of laws governing pollution of water, environment, farming practices and waste discharge in all countries. A second major management issue relates to land use/land cover change. The Great Lakes catchments have been adversely affected by farming, urbanization and infrastructures construction. Most original forests have been cut. Rivers have been diverted for irrigation and drilling of wells, withdrawal of waters from the lakes for farming, recreation and household use are prevalent. Today water conflicts are found in communities living around all the lakes reviewed in this paper. Lake Naivasha has a unique conflict between the large-scale farmers, urban dwellers and indigenous people who feel displaced and marginalized. Other management issues that require urgent considerations include preservation of lake shoreline, use of safe pesticides, fishery management, fertilizer use, introduction and control of alien species, urban planning and development and environmental monitoring. The community management bodies that have been established have not been sustainable in the long term because of framework of their articles of formation. Some of these bodies did

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not anticipate the rapid changes that have taken place. As such, their articles of association did not for example define what is a permanent building, and what is a cultivation, definition and provision of buffer zones beyond which no human activity is allowed was not included, no provision was made for free access or otherwise of animals to the littoral zone and to water direct from the lake. The rapid increase of human and animal population, the introduction of large scale farming and industry, the attendance pesticides, fertilizers, sewer and industrial pollution of lakes have become serious and raised conflicts between the stakeholders. 3.1 Capacity Building A number of researchers have conducted studies on these lakes that have great bearing on their management plans. However, there is lack of capacity building for the local scientists, community and young potential researchers. In some cases a number of students from external institutions have conducted useful research and earned M.Sc. degrees with only a few local students involved. Upon completion there is no one locally to carry on research. The other issue is failure to engage local communities or when engaged in projects they do so as a form of employment but do not integrate it as part of their daily life. Hence, at the end of the project they drift way from the lakes’ ecosystem management. There is also the issue of use of indigenous expertise trained locally and have excellent ideas and knowledge on these lakes. They are, however, not encouraged/assisted or supported through projects and research funding to ensure maximum implementation of lessons learnt from their indigenous knowledge. One good way will be to adopt a multidisciplinary approach in capacity building to resolve the challenges posed by different approaches perspectives to lake management. 3.2 Sharing, Transfer and Dissemination of Information Even though each lake is unique and share some common problems in some case, the lessons learnt from one basin are not transferred amongst the stakeholders involved in other basins riparian communities. There is therefore, need for information sharing, improving on lessons learnt and achievements from amongst all researchers, stakeholders involved and catchments basins in order to improve their management. The incorporation of scientific information and research in the lake management programs is also needed. 4. Policy Options

The feasibility of policy options in the Great Lakes are looked upon in conjunction with the establishment of the community/regional integration of their development authorities. The authorities offer good prospect for the success of the proposed policies, in that they provide an enabling environment for respective riparian communities/countries to work together towards common goals. Some means are required in order to incorporate all countries in the catchments basins in the management structure of the respective lake. Since, even though some may not share the lake shore, they form a significant part of the lakes catchments area and may be principal polluters, being the source of the highest sediment load and the original entry point for invasive species; for example Rwanda, Burundi and Democratic Republic of Congo in the case of Lake Victoria.

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Despite these enumerated drawbacks there have been good demonstrations of projects that have been initiated to save the lakes. The Lake Victoria Environmental Management Project (LVEMP), the Lake Naivasha Riparian Association (LNRA), the Lake Nakuru Community Development Organization (LNCDO), the Lake Baringo Community Based Land and Water Management Project (LBCBLWMP), Lake Chad Basin Commission (LCBC) have all demonstrated that riparian communities, national governments and international communities can work together for the restoration of the lakes environment. The experiences learned from each of the projects differ but in general there are positive results in tackling the issues and promotion of public awareness.

The Great Lakes Authorities need to be expanded to cover management agreements in the following areas:

• The development of a common environmental management policy; • The development of special environmental management strategies; • Taking measures to control trans-boundary air, land and water pollution

arising from developmental activities; • Integrating environmental management and conservation measures in all

development activities; • Strategies for poverty reduction • Improvement of health care facilities and control of endemic diseases • Construction and /or improvement of infrastructures and • Provision of educational facilities.

There are long term benefits that will accrue from a regional vision that results from harmonised policies and strategies. These benefits include but are not restricted to the following areas identified by the Regional Task Force, 2003:

• The population will prosper from livelihood derived from the properly managed resources, ecosystems and a clean healthy environment.

• Sustainable and equitable utilisation of resources will improve production and increase income generated from the same.

• Improved income and quality of life will create a healthy, well educated society with high quality of life, well developed infrastructure and free from poverty.

• Stabilisation of population growth and demographic changes will naturally develop from a healthy competent and productive population that is able to utilize and manage natural resources sustainably to achieve economic growth and development.

• Better governance, institutions and policies will arise from an empowered and gender sensitive community that recognizes its rights and upholds its laws in order to safeguard its institutions and policies.

5. Financing Financing of lake management projects have come from national and urban (local) governments, community levies, and international development facilities like the World Bank, the Global Environmental Facility (GEF), National Science Foundation (NSF), World

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Wildlife Fund (WWF), the regional bodies and bilateral technical assistance organizations. With the erosion of most government economic base, the financial resources from central and local governments have declined considerably. Community organizations financial contributions have depended on the economic viability of their trade in commodities they produce. The resources from development facilities organizations have been tied to projects with limited time-frame and objectives. At the end of the projects, the progress in ecosystem management has declined or stopped. Therefore, there is a need for a new financing framework that will involve the governments, communities and official donor assistance groups in a more sustainable manner. Special dispensations should be made for those benefiting from the lakes’ resources to contribute to their sustainable ecosystem management through taxes, levies and duties. The use of national planning and budgeting, as a stimulant for sustainable lake basin management would be ideal. While at the policy level a mechanism of flexible and effective funding that is founded on participation, transparency and accountability should be put in place.

6. Recommendations for Future Actions

In order to achieve the above management objective and using the recently concluded causal chain analysis (Odada, et. al. 2003b), it might be prudent to initiate at the national levels the following policy changes:

1) Over fishing

Establish:

• Quota for fishing • Quota for processing • Review of the rules and regulations and existing policies and protect endangered fish

species like some wild animals • Civic education and awareness campaign to riparian communities to use fish resources

sustainable. • Encourage fish farming and forming of co-operatives 2) Destructive Fishing Practices • Strengthen the monitoring and enforcement of restrictions • Enforce the rule of law • Provision of civic education and awareness, empower and involve more communities in

management • Imposition of size restrictions on fish processing factories • Provision of credit to artisan fishers • Involve politicians to support sustainable fishing 3) Pollution • Accreditation of Analytical Laboratories for standards enforcement. • Liberalisation of waste disposal activities to involve the private sector and communities.

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• Revision of regulations in urban planning that has not taken into account environmental issues and improvement of monitoring and enforcement.

• Improvement of natural resource management and farming practice through training, better governance and technologies in agriculture.

• Stronger vetting of technologies that are being promoted by the national and international agencies.

• Strengthen enforcement of regulations requiring effluent treatment in municipalities and industries.

• Incorporate all stakeholders in drafting of regulations and in monitoring and enforcing agreed upon regulations.

• Integration of institutional framework at two levels: national and regional • Integration of regulations and laws at two levels: national and regional. • Legal and economic empowerment of institutions e.g. Lake Victoria Fisheries

Organization (LVFO). • Enforce compliance to international conventions e.g. RAMSAR, CITES, and the

Biological Diversity Convention of Agenda 21. • Strengthening the capacity of National Environmental Protection Authorities in order to

be able to be more effective. • Demand management should be included as a priority option to improve efficient

utilization of water in order to reduce anthropogenic lake degradation. • Address trans-boundary lakes issues so that the management authorities are answerable

not only to member states but also to the communities. • Lake management approaches for these water bodies should address community poverty

issues as well as diseases affecting them and their inability and/or unwillingness to apply scientific knowledge to resolve sustainable lake management issues.

4) Recommendations for future research • Water quality assessment and improvement of use. • Study of socio-cultural issues (holistic rather than focusing within the fisheries sector,

encompassing also health, agriculture, education, etc. within the entire lake basin). • Resource inventory, mapping and use (including mapping of critical resources). • Assessment and harmonisation of legal and institutional status of National Acts, regional

and international Treaties and Conventions. • Study of the biology of the exotic species such as Nile perch, which is suspected to have

up to three different sub-populations. • Harmonization of lake basins authorities in order to bring coherence in issues arising

from different/interdisciplinary conflicts in lake management. Acknowledgement: The author is grateful to Samuel Ochola for literature search and assistance in putting this paper together. 6. References

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1. Aryamanya-Mugisha, H. (1993) Pesticides and Environmental Degradation. Proceedings of Uganda National symposium on Pesticide Information Network. (UNSPIN). APEMAF publication No. 6, 1-2.

2. Bugenyi F.W. and Magumba, K.M, (1996). The present physico-chemical ecology of Lake Victoria, Uganda. In: Johnson, T.C. and Odada, E.O. (Eds.). The Limnology, Climatology and Paleoclimatology of East African Lakes: Gordon and Breach, Toronto, pp. 337-355.

3. Hecky R.E, and Bugenyi F.W. (1992) Water quality: hydrology and chemistry of the African great Lakes and water quality issues; problems and solutions. Mitteilungen-Internationale Vereinigung fur Theoretische und Angewandte Limnologie, 23: 45-54

4. Hecky R.E. (1993). The Eutrophication of Lake Victoria. Verh. Int. Ver. Limnol. 25, 39-48

5. Hutchinson P and Kolawole, A., (1987) Environmental change and the South Chad Irrigation Project (Nigeria): Journal of Arid Environments, no. 13. p 170

6. Mugidde R. (1993). The increase of phytoplankton productivity and biomass in Lake Victoria (Uganda). Proc. Int. Ass. Theor. Appl. Limnol. 25, 846-849

7. Odada, E.O, Olago, D.O, Bugenyi, F, Kulindwa, K, Karimumuryango, J, West, K, Ntiba, M, Wandiga, S, Aloo-Obudho and Achola, P (2003a) Environmental assessement of the East African Rift Valley lakes. Journ. Aquatic Sciences 65(2003) 254-271.

8. Odada E.O, Olago, D.O, Kulindwa, K, Ntiba, M and Wandiga, S. (2003b) Mitigation of environmental problems in Lake Victoria, East Africa: Causal chain and policy options analysis. AMBIO. A jounal of the human environment. In press.

9. Oguttu-Ohwayo R. (1990) The decline of native fishes of Lake Victoria and Kyoga (East Africa) and the impact of introduced species, especially the Nile perch, Lates niloticus and the Nile tilapia, Oreochromis niloticus. Environ. Biol. Fisheries, 27, 81-86

10. Talling J.F. (1966). The annual cycle of stratification and phytoplankton growth in Lake Victoria (East Africa). Int. Rev. hydrobiol, 51, 545-621

11. Taylor D, Klaine, S.J, Carvalho, F.P, Barcelo, D. and Everaarts, J. (Eds.). (2003) Pesticide Residues in Coastal Tropical Ecosystems. Distribution, fate and effects. Taylor and Francis. London and New York Pp 49 – 80

12. Verburg P, Hecky, R.E. and Kling, H (2003) Ecological consequences of a century of warming in Lake Tanganyika. Science Vol 301. pp 505 – 507.

13. Verschuren T.J. Johnson, Hedy J. King, D.N. Edgington, P.K. Leavitt, E.T. Brown, M.R. Talbot and R.E. Hedy (2002) History and timing of human impact of Lake Victoria, East Africa. Proc. Roy. Soc. London B. 269, 289 – 294

14. Wandiga S.O, Lalah, J.O and Kaigwara, P.N. (2003) Pesticides in Kenya, In: Taylor, D, Klaine, S.J, Carvalho, F.P, Barcelo, D. and Everaarts, J. (Eds). Pesticide Residues in Coastal Tropical Ecosystems. Distribution, fate and effects. Taylor and Francis. London and New York Pp 49 – 80

15. Wandiga S.O. (2001) Use and distribution of organochlorine pesticides in Africa. Pure and Applied Chemistry 73 (7) 1147-1155.

16. Witte F., Goldschmidt, T., Wanink, J.M., Oijen, M.J.P. van, Witte-Maas, E.L.M. and Bouton N. (1992). The destruction of endemic species of flock: quantitative data on the decline of the haplochromine cichlids of Lake Victoria. Environ. Biol. Fisheries. 29, 1-28.

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17. WWF SARPO, (2001) In Lake Malawi/Nyasa Ecoregion: Biophysical Reconnaissance. A.J, Ribbink.

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Table 1. Unique characteristics of the lakes L. Victoria • The second largest fresh water lake in the world

• Hosts 500+ species of cichlids • Supports about 30 million people • Source of River Nile • Fastest cichlid fish evolution recorded

L. Tanganyika • Approximately 12 million years old • The oldest of African lakes and second to lake

Baikal in age and depth • Hosts 250+ species of cichlids • Hosts about 600 non cichlid species • Hosts about 2,000 species of plants and animals • Supports about 10 million people

L. Malawi/Nyasa • Approximately 2 million years old • Hosts 700+ species of cichlids • Supports about 11 million people

L. Naivasha • Only fresh water lake in the Kenya’s Rift Valley floor

• Hosts over 400 species of birds • Habitat to several animal species • Supports about 250,000 people • Only lake with community management

L. Nakuru • Home to flocks of flamingo birds, greater and lesser cormorants, 1.5 million birds and wildlife species

• Tourist attraction site • Supports 400,000 people

L. Baringo • 300 species of birds identified • Home to fish and animal species • Aesthetic beauty

L. Chad • Supports 20 million people • Once second largest wetland in Africa • Fastest dying lake in Africa • Hosts 93 species of fish

L. Kariba • One of the largest man made lakes in the world • Source of water, electricity, fisheries, recreation

and bird watching • Home to birds and animal species

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Table 2. Physiographic statistics for Lake Victoria Latitude 0o 21’N Longitude 3o 0’ S Age About 400,000 years Altitude 1100 m Length 337km width 240km Surface Area 68,870 km2 Volume 2,760 km3 Shoreline 3450 km Perimeter 3200 km Maximum depth 84 m Mean depth 40 m Catchments 184,000 km2 Oxygenated Zone -35 m Transparency 1.5m Temperature 24oC- 28oC pH 7.6-8.2

Table 3. Physiographic statistics for Lake Tanganyika Latitude 03o 20’-08o 48’S Longitude 29o 03’-31o 12’ E Age About 12 million years Altitude 773 masl Length 673 km width 12-90 km, average about 50 km Surface Area 32,600 km2 Volume 18,880 km3 Shoreline 1,838 km Maximum depth 1,320m in north basin, 1,470 m in south basin Mean depth 570 m Catchments 220,000 km2

Stratification Permanent, meromictic Oxygenated Zone -70 m depth in north, -200 m depth in south Transparency 7-16m Temperature 23-27oC pH 8.6-9.2 Salinity About 460 mg/l

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Table 4. Physiographic statistics for Lake Malawi/Nyasa Latitude 90 34’-14o 40’S Longitude 33o 50’-33o 36’E Age About 2 million years Altitude 471m Length 505/603km width 87km Surface Area 43,935-52,461km2 Volume 84,000km3 Shoreline 1500km Maximum depth 704-785m Mean depth 290-426m Catchments 126,500km2 Oxygenated Zone 170-210m Transparency 12-20m Temperature 22.1-29.5oC (depending on depth) pH 7.9-9.1 surface, 7.8 (300m deep)

Table 5. Physiographic statistics for Lake Naivasha Latitude 0o 42’- 0o 50’S Longitude 36o 16’-36o 26’E Age 2 million Altitude 1885 m Length 17km width 14km Surface Area 180-210km2 Volume 50-600 m3 Perimeter 130 km Maximum depth Crescent island, 15 m Mean depth 4-6 m Catchments 3,292 km2 Oxygenated Zone 5.6-8.2 mg/l Temperature Mean Max. 19.5-23oC, Min. 16oC pH 8.5-9.0 Salinity 150-185 mg/l Evaporation 1735-1865 mm/yr

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Table 6. Physiographic statistics for Lake Nakuru Latitude 0o 22’S Longitude 36o 05’ E Altitude 1,759 masl Surface Area 42 km2 Volume 0.092 km3

Maximum depth 4.0 m Mean depth 2.5 m Catchments 1800 km2 Oxygenated Zone Mean 6-8mg/l Evaporation 1539 mm/yr Temperature 18.2oC pH 10.5 Salinity 122mg/l

Table 7. Physiographic statistics for Lake Baringo Latitude 0o 32’ – 0o 44’N Longitude 36o 02’ – 36o 08’E Altitude 975 m asl Length 22 km Width 10 km Surface Area 129 km2 Maximum depth 8 m Catchments 6,820 km Conductivity 420 µS/cm Secchi depth 0.1 m Temperature 21 – 31 oC PH 8-9

Table 8. Physiographic statistics for Lake Chad Latitude 12o 20’-14o 20’ N Longitude 13o 00’-15o 20’E Altitude 280 m asl Surface Area 10,000-25,000 km2 Volume 72 km3 Shoreline 500-800 km Maximum depth 10-11m Mean depth 1.5 m Catchments 2,426,370 km2 Temperature 20 – 30 oC pH 7.2-8.0

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Table 9. Physiographic statistics for Lake Kariba Site Name AFR-04 Lake Name Lake Kariba

State

Southern, Zambia; and Matabeleland North and Mashonaland West, Zi

Country Zambia and Zimbabwe

Latitude 17:2S Longitude 27:5E Altitude [m] 485

Photo : C. H. D. Magadza Surface area [m2] 5,400,000,000 Volume [m3] 160,000,000,000

Maximum depth [m] 78 Mean depth [m] 31

Water level control Regulated Normal range of annual

water level fluctuation [m] 2.5

Length of shoreline [m] 2,164,000 Residence time [yr] 3

Catchments area [m2] 663,000,000,000 Hours of bright Sunshine

[hr yr-1] 2,920

Solar radiation [MJ m-2 day-1] 23.9 Freezing period None

Mixing type Monomictic Annual fish catch [t yr-1] 11,000

18

Table 10. Physiographic Statistics for Lake Malawi/Nyasa Site Name AFR-13 Lake Name

Lake Nyasa (Lake Malawi)

State

Niassa, Mozambique; Malawi; and

Ruvuma, Tanzania

Country Mozambique, Malawi and

Tanzania Latitude :1S Longitude 34:5E Altitude [m] 500

Photo : H. Bootsma

Surface area [m2] 6,400,000,000 Volume [m3] 8,400,000,000,000 Maximum depth [m] 706 Mean depth [m] 292

Water level control Regulated Normal range of annual

water level fluctuation [m] 1.25

Length of shoreline [m] 245,000 Residence time [yr] -

Catchments area [m2] 6,593,000,000 Hours of bright Sunshine

[hr yr-1] 2,860

19

Table 11. Flora (Macrophytes, Phytoplanktons) and Fauna (Fish) found in the lakes

species Victoria

Tanganyika

Malawi Naivasha

Nakuru Chad Baringo

Kariba

A. antinorii +

O. spirilus niger + M.salmoides + T. zillii + + + O.leucostictus + O.niloticus + + L.reticulata + O.mykiss + B. amphigrama + Microcystis aeruginosa (Kutz.) Kutz

+

Cyanophyta + Chlorophyta + Bacillariophyta + Cyperus papyrus + + + + Eichhornia crassipes + Pistia stratiotes + + + + Salvinia molesta + Wolffia arrhiza + Nymphaea caerulea (water lilies)

+ + + +

Potamogeton schweinfurthii

+ +

P. pectinatus + P. octandrus + Najas pectinata + Ipomoea aquatica + Cyrtobagus salviniae + Samea multiplicatus + Neochetina bruchii + Microcystis aeruginosa + + Lyngbya + Oscillatoria + Melosira + small-toothed carp (Aplocheilichthys antinorii)

+

Barbus amphigramma + + large-mouth bass (Micropterus salmoides

+

Citharinus citharus + Salvinia auriculata + Baswamp crayfish (Procambarus clarkii)

+

Ceratophyllum demersum

+

Potamogeton pusillus + Lagarosiphon ilicifolius

+

Vallisneria aethiopica + Najas sp +

20

Cylindrospermopsis raciborskii

+

Anabaena circinalis + + + + + Lyngbya sp + Synedra acus, + Melosira granulata + Peridinopsis cunningtonii

+

Tetraedron minimum. + Brachionus falcatus + Bosmina longirostris + Sargochromis codringtoni

+

Synodontis zambezensis + + Tilapia rendalli + + + + Claiasr gariepinus + Synodontis nebulosus + + Schilbe mystus + + Heterobranchus longifilis

+

Malapterurus electricus + Eutopius depressirostris

+

Sarotherodon mossambicus

+

Brachionus calyciflorus + Keratella tropica + Barbus gregori + + Clarius mossambicus + + Labeo cylindricus + Citharanus distichodoides

+

Labeo coubie + Heterotis niloticus + Alestes ssp. + + Lemna perpusilla + Spirodela polyrhiza + Azolla africana + + Neptunia oleracea + Potamogeton spp. + + Vallisneria spp. + Ceratophyllum demersum

+ + +

Utricularia spp. + + Spirulina platensis + + Cyperus laevigatus + Typha domingensis + + Sporobolus spicatus + Paradiaptomus africana

+

Brachionus spp. + Oreochromis alcalicus grahami

+

Varicorthinus nyassensis

+

Labeo mesops + Opsaridium +

21

microcephalus Bagrus meridionalis + Bathyclarias sp + Oreochromis squamipinnis

+

O. shirana + O. saka + Haplochromis kiwinge + + H. livingstonii + + H. taeniolatus + + H. phenochilus + + Lethrinops sp + Pseudotropheus sp + Labidochromis sp. + Labeotropheus sp. + Serranochromis thumbergi

+

Rhamphochromis sp + Thpha, Carex + Stolothrissa tanganikae + Limnothrissa miodon + Lamprichthys tanganicus

+

Engraulicypris minutus + Bathybates minor + Bolengorochromis microlepis

+

Lates mariae + L. angustifrons + L. stappersi + Phragmites spp + Vossia + Hydrilla verticillata + Polygonum spp + Tilapia niloticus + Labeo victorianus + Protopterus aethiopicus + Bagrus docmac + Scibe + Melosira nyassensis + Lyngbya contorta + Pediastrum clathratum + Glenodinium spp. + cenedesmus spp + Cyclotella spp + Fragillaria spp + scillatoria spp + Kirchneriella sp + Treubaria sp + Chroococcus limneticus

+

Chrysochromulina parva

+ +

Chromulina sp. + Nitzschia sp + + Stephanodiscus sp. +

22

Strombidium sp + Closterium aciculare + Pediastrum sp + Botryococcu sp. + Microcystis sp. + Melosira granulata + + Surirella muelleri + Cylindrospermopsis raciborskii

+

Lyngbya sp + Synedra acus + Peridinopsis cunningtonii

+

Synechococcus spp + Anabaenopsis arnoldii + A. elenkinii + Navicula elkab + Nitzschia frustulum + Chroococcus minutus +

Source: World Lakes Database, A Directory of African Wetlands,