Chapter 8. Synthesis for all taxa Holland, R.A.¹, Garcia, N.¹, Brooks, E.G.E.¹ and Juffe, D.¹, with contributions from: Howard, G.² (Section 8.2.3); Foster, M.N.³ (Section 8.3.4); Harrison, I.³, Upgren, A.³, Alonso, L.E.³ (Section 8.5); Matthews, J.H.4, Wickel, A.J.5, Freeman, S.5 and Thieme, M.L.5 (Section 8.6) 1 Freshwater Biodiversity Unit, IUCN Species Programme, Cambridge, CB3 0DL, UK 2 Global Invasive Species Coordinator, IUCN, Wasaa Conservation Centre, Mukoma Road, P.O. Box 68200, 200 Nairobi, Kenya 3 Conservation International, 2011 Crystal Drive, Suite 500, Arlington, Virginia 22202, USA 4 Current address: Conservation International, 2011 Crystal Drive, Suite 500, Arlington, VA 22202, USA 5 WWF Conservation Science Program, World Wildlife Fund, 1250 Twenty-Fourth Street, N.W., Washington, DC 20037, USA MAIN: Fishers return to Senanga on the Zambezi River, at the southern end of the Barotse fl oodplain. © JENS KIPPING RIGHT: High species diversity in a fi sh catch at Ilagala market, Lake Tanganyika, Tanzania. © KLAAS-DOUWE DIJKSTRA IUCN AFR2011_pp228-269_chapter 8_synthesis v2.indd 228 4/3/11 19:08:39 CONTENTS 8.1 Introduction 230 8.2 Freshwater biodiversity across Africa 230 8.2.1 Patterns of richness and main threats 230 8.2.2 Distribution of threats to African freshwater species 235 8.2.3 Biological invasions affecting freshwater species in Africa 244 8.3 Conservation action 247 8.3.1 Congruence between taxonomic groups 247 8.3.2 Protected areas for freshwater ecosystems 247 8.3.3 Key Biodiversity Areas for freshwater species 249 8.3.4 Alliance for Zero Extinction – AZE sites 249 8.4 Livelihoods dependence on freshwater species 251 8.5 Areas for further work 258 8.5.1 Regions of Data Defi cient species and threatened species 258 8.5.2 Comparing distributions of Data Defi cient species with records of new species. 262 8.6 The future of African freshwaters 264 8.6.1 Climate change and African freshwater conservation: seeing the future through the past 264 8.6.2 African waters: special qualities and challenges 265 8.6.3 A short history of African eco-hydrological dynamism: the past 100,000 years 265 8.6.4 Signs of anthropogenic climate change in Africa 267 8.6.5 Projecting trends and responses 267 8.6.6 Implications for facilitating healthy responses to freshwater change 268 IUCN AFR2011_pp228-269_chapter 8_synthesis v2.indd 229 4/3/11 19:08:42 SYNTHESIS FOR ALL TAXA SYNTHESIS FOR ALL TAXA | CHAPTER 8 Platythelphusa maculate (LC), a small crab endemic to Lake Tanganyika, hides in empty Neothauma shells. © SASKIA MARIJNISSEN 8.1 Introduction world’s species that are dependent on freshwater habitats (Table 8.1) and, as such, understanding the distribution In this synthesis chapter, we combine information and status of this biodiversity, the threats which it faces presented in chapters 3 to 7 and consider the status and and the actions that need to be taken is key to ensuring its distribution of freshwater biodiversity across mainland continued survival and provision of benefi ts to people. continental Africa. We present a combined analysis for all fi sh, molluscs, crabs, odonates and plants, to illustrate patterns of richness and threat across African countries 8.2 Freshwater biodiversity across Africa and consider what drives these patterns. We discuss the role that existing protected areas have in conserving 8.2.1 Patterns of richness and main threats freshwater biodiversity and identify the location of Key Biodiversity Areas and Alliance for Zero Extinction sites, In previous chapters, analysis has been conducted at the as these represent important focal areas for conservation sub-catchment scale, as this represent the logical mapping effort. Finally, we examine the future of African freshwaters unit for freshwater species. Here, we fi rstly consider and consider one of the most signifi cant threats that they patterns at the country level to highlight important patterns 230 face. Africa is home to a signifi cant proportion of the relevant for policy makers. IUCN AFR2011_pp228-269_chapter 8_synthesis v2.indd 230 4/3/11 19:08:46 CHAPTER 8 Figure 8.1. Richness of species across continental Africa based on occurrence in countries. | SYNTHESIS FOR ALL TAXA SYNTHESIS FOR ALL TAXA Table 8.1. Estimated number of inland water At the country scale, richness for all freshwater groups dependent species by major taxonomic group. in Table 8.1 decreases from the equator. Such a pattern Data from the IUCN Red List of Threatened Species - has been suggested to represent a general rule in ecology September 2010. named after Eduardo H. Rapoport, who fi rst described it for Number mammals. Although Rapoport’s Rule has been called into question in recent years (Gaston 1998), patterns shown in Number of of species % of global Figure 8.1 demonstrate that, at this course scale, richness Taxon described assessed total found of freshwater taxa is highest in equatorial countries and Group species in Africa in Africa decreases with latitude. Crabs 1280 120 9% Fish >15000 2836 c. 19% Equatorial countries also contain signifi cant numbers Molluscs >5000 624 c. 12% of species classifi ed as being of conservation concern Odonates 5680 705 12% according to the IUCN Red List (Figure 8.2), with the highest Amphibians 4251 624 15% concentrations occurring in a band across the centre of Waterbirds 868 279 32% the continent through Tanzania, D. R. Congo, Uganda and Mammals 145 32 22% Kenya. However, high numbers of threatened species are 231 IUCN AFR2011_pp228-269_chapter 8_synthesis v2.indd 231 4/3/11 19:08:50 Figure 8.2. Richness of threatened species across continental Africa based on occurrence in countries. SYNTHESIS FOR ALL TAXA SYNTHESIS FOR ALL TAXA | CHAPTER 8 also found in countries extending down the east coast sub-catchments in western Africa, and sub-catchments (Mozambique, Malawi) and up the west coast (Cameroon, that trace the course of major rivers through the centre of Nigeria). To the far north of the continent, Morocco also the continent, primarily in D. R. Congo (Figure 8.3). Areas has high numbers of threatened species, mainly due to of lowest richness correspond with arid regions, such as over-abstraction of water associated with agricultural the Sahara, Namib, and Kalahari deserts, where there are production in this comparatively arid landscape. Moving few suitable habitats for freshwater species. south of the equator, development of South Africa’s water resources and the spread of invasive species has led to Africa is home to some species with remarkable adaptations high numbers of threatened species in this country. that enable them to cope with ever changing habitats that arise through fl ooding or seasonal rainfall patterns. Perhaps By combining information on fi sh, odonates, crabs, the most famous such adaption is found in the Lungfi sh molluscs and plants at the sub-catchment scale, a clearer (Protopterus annectens (LC)), which is able to cocoon picture of the drivers of biodiversity patterns within and itself in mud when its fl oodplain habitat dries up. Less well between countries emerges. Across equatorial countries, known are the annual Killifi sh (e.g., Nothobranchius spp.) areas of highest richness are driven by the diversity of that exploit temporary pools or even puddles in roads as 232 species in the Great Lakes of eastern Africa, rivers in coastal habitats. When these temporary water bodies dry up, the IUCN AFR2011_pp228-269_chapter 8_synthesis v2.indd 232 4/3/11 19:08:54 CHAPTER 8 Figure 8.3. Combined richness of fi ve freshwater groups at the sub-catchment scale. Species richness = number of species per river/lake sub-catchment. | SYNTHESIS FOR ALL TAXA SYNTHESIS FOR ALL TAXA eggs of the fi sh can remain buried in the mud for years until water once again returns to awaken them. In the most arid regions, where freshwater species coexist with human populations, there is often intense pressure on water resources, creating areas of high concentrations of threatened species. For example, in The African lungfi sh Morocco and Algeria sub-catchments containing high (Protopterus annectens) numbers of threatened species are situated along the (LC) normally lives on coastline where the majority of the human population fl ood plains, and when is found. Across the continent a similar pattern is often these dry up it survives found with threat richness corresponding to areas of by secreting a thin slime high human population density (Figure 8.4). Although a around itself, which range of different drivers of threat are identifi ed, broadly dries into a protective speaking, results confi rmed fi ndings from other studies cocoon. that activities associated with agricultural production © ROGER BILLS/SAIAB 233 IUCN AFR2011_pp228-269_chapter 8_synthesis v2.indd 233 4/3/11 19:08:58 Figure 8.4. Combined richness of threatened species based on the fi ve freshwater groups at the sub-catchment scale. Threatened richness = number of threatened species per river/lake sub-catchment. SYNTHESIS FOR ALL TAXA SYNTHESIS FOR ALL TAXA | CHAPTER 8 and urbanisation within catchments represent the most management zones. The transmission of threats in this way pervasive threat to species and the health of the world’s requires a co-ordinated approach to management between freshwaters (Allan 2004). countries. However, there is a long history of disputes arising due to such transboundary issues, principally relating to use Based on sub-catchment analysis, the high concentration of water resources. Realisation that the connected nature of of threatened species recorded for Tanzania (Figure 8.2) freshwater systems means all stakeholders need to be jointly arises as the country borders Lakes Victoria, Tanganyika involved in management actions has the added benefi t of and Malawi.