Fisherman collecting net, Sanaga River, Cameroon. Photo © Kevin Smith
Central Africa supports the highest diversity of freshwater species within Africa, of which a significant proportion are threatened. As development across the region increases the status of central Africa’s freshwater biodiversity will worsen unless successful conservation measures can be undertaken.
An immediate priority is to implement conservation actions in the basins that have been identified to contain exceptional levels of species diversity and those containing high levels of threatened species. These actions need to address the total impacts of key threats, such as the downstream impacts of deforestation leading to sedimentation, and agricultural and mining pollution, and the upstream impacts of dams through the loss of riverine habitat and impacts to migration routes and natural dispersal. If this situation continues along current trends some species will become extirpated from catchments, and given the high levels of endemism in the area, are at risk of becoming globally Extinct. Ecosystem level consequences from the loss of freshwater species are poorly understood, as are the knock on effects to the services they provide to human populations so a precautionary approach is required. It is often the poorest communities that rely most heavily upon freshwater resources, such as for protein source, for building materials, and for income when subsistence harvest surpluses are sold. For instance, in the Salonga river system, revenue’s from fishing account for 61% of cash income, and unlike agriculture, provide a year-round revenue. In these cases fishing acts as a ‘bank in the water’, allowing the local population access to an income source quickly to pay for basic necessities as and when costs arise. Consequently, this poorest section of the community, which has few alternative livelihood options, suffers heavily when species are lost and ecosystems are degraded.
Central Africa contains the highest proportion of Data Deficient species of any region in Africa (see IUCN Red List Status), with a range from 19% of mollusc species to 32% of crab species falling into this Category, and up to 45% of odonates if only endemics are considered. Areas of particular need for research can be highlighted through mapping the extent of Data Deficient species ranges where available (see Chapter 8 of the report). In addition to those areas also identified as centres of species richness, it is also clear that there is a deficit of information in the headwater regions of the River Congo.
Further research and survey work are needed to gather more information on these species’ distributions, taxonomy, ecology and their utilisation and threats. Due to their cultural history, central Africa and DRC in particular are greatly understudied areas, and more data are required to fill this information gap in order to complete a more comprehensive assessment of the entirety of Africa’s freshwater systems. Findings from future field surveys will undoubtedly uncover more threatened species, and will likely add to the growing body of evidence that freshwater biodiversity has great value to local livelihoods.
Protected areas need to be specifically designed for the protection of freshwater species, particularly those that have restricted ranges or limited numbers of congregation, migration or breeding sites. Design must take good account of the high connectivity within freshwater systems if the protected areas are to be effective. For example, the success of a protected area established for freshwater species conservation may be greatly reduced if upstream activities, often some distance outside the protected area boundaries, such as excessive water withdrawal or regulation, alter the downstream flow regime within the protected area to the detriment of those species being protected. A good understanding of the threats and ecology of the target species, as provided here, is often essential for optimising the design of the protected area. As central Africa is relatively un-developed, there is still an opportunity to identify and protect relatively pristine areas, and the development of protected areas and parks is an essential component of conservation recommendations. It is, however, critical that there are sufficient funds and the means to implement and manage conservation areas, particularly in the more isolated areas, most at risk from human encroachment. Without an increased capacity to manage these areas protected areas may be of little conservation value.
Key Biodiversity Areas are sites of global significance for biodiversity conservation. Standard criteria can be applied to identify areas pivotal for the maintenance of species populations important for conservation, based on a framework of vulnerability and irreplaceability. Irreplaceability refers to the spatial options for conservation of a species, in other words, how unique is a site critical for a species existence, and what other options for its conservation exist. Vulnerability is a measure of the probability that a sites’ biodiversity will be lost in the future. In freshwater terms these are defined within a practicable management unit, such as a river or lake basin. As part of the Pan-Africa assessment the IUCN Species Programme has developed a series of criteria to identify sub-catchments as Key Biodiversity Areas based on vulnerability and irreplaceability. These are:
Criteria 1: A site is known or thought to hold a significant number of one or more globally threatened species or other species of conservation concern. This is the vulnerability based criteria as it identifies sub-catchments containing species with the highest risk of being lost in the future. To apply this criterion each species must be assessed using the IUCN Red List, with those classified as Vulnerable, Endangered or Critically Endangered triggering KBA qualification.
Criteria 2: A site is known or thought to hold non-trivial numbers of one or more species (or infraspecific taxa as appropriate) of restricted range. This is the first of the irreplaceability criteria. Threshold values for restricted range differ between taxonomic groups. For fish, crabs and molluscs the threshold value was set as less than 20,000 km2 and for odonates the threshold value was set at less than 50,000 km2.
Criteria 3: A site is known or thought to hold a significant component of the group of species that are confined to an appropriate biogeographic unit or units. This is the second of the irreplaceability criteria. Freshwater Ecoregions of the World were utilised as the biogeographic units and for each subcatchment the proportion of species that occur in just one ecoregion was calculated. A sub-catchment qualifies under criterion 3 if 25% or more of the species within it are restricted to the ecoregion.
A KBA can be identified under the vulnerability and the irreplaceability criteria simultaneously; indeed many species trigger more than one criterion. A KBA network defined according to the presence of species meeting the criteria would be expected to include all sites that play a crucial role in maintaining the global population of these species.
KBA analysis for the irreplaceability criterion includes mapped species that are currently listed as Data Deficient. Additional field surveys may prove a species to be more widespread, however, until known otherwise, we should assume these species have restricted ranges and are of conservation concern. Based on these criteria we identified 471 level 6 sub-catchments in central Africa that would qualify as potential freshwater Key Biodiversity Areas. These sub-basins may qualify as KBAs independantly or as a combination of connected subcatchments, depending on local management options, and can be applied to define a graduation of freshwater protected areas, from a freshwater focal point, to a critical management zone or a catchment management zone. For instance, a single level 6 sub-catchment, such as that associated with the Western Equatorial Crater Lakes, might be defined as the appropriate management unit for Stomatepia mongo and would therefore qualify as a KBA in its own right. More often, the most practical management unit will consist of connected level 6 subcatchments, such as those making up the Ubangi River.
Potential Key Biodiversity Areas (KBAs) for the central Africa region, mapped to river sub-catchments.
EIAs, when correctly undertaken, are a valuable tool for informing the development planning process, particularly where threatened or restricted range species are expected to be found. This report (and the IUCN Red List website) provides data useful to the initial planning stages of EIAs, as the expected species composition of every sub-catchment in the region can be identified, along with information on species ecology, and their conservation status in the wider global or regional context. This information is of great value in that it enables the person conducting the EIA to better understand the conservation value of a species through knowing whether it is endemic to a particular river basin or is threatened. It should be noted, however, that the spatial data presented are of too low resolution to replace the need for additional field surveys as required for a fully comprehensive EIA.
The interaction between anthropogenic requirements from a freshwater ecosystem and its requirements for maintaining basic ecological function is complex, and many human activities if badly managed can have direct and devastating impacts on freshwater ecosystems. With this in mind, water resources must be managed in a way that the ecological requirements of freshwater species are considered when planning and managing use of hydrological resources, in order to ensure the maintenance of goods and services that those ecosystems provide. Integrated Water Resource Management (IWRM) is a concept of integrating the work of conservation in maintaining ecosystem functions whilst maximising economic and social benefits from a given river basin (see the Global Water Partnership Toolbox for more information on IWRM and case studies, at www.gwptoolbox.org). A component of IWRM is the management of Environmental Flows, defined as “the water regime provided within a river, wetland or coastal zone to maintain ecosystems and their benefits where there are competing water uses and where flows are regulated. Environmental flows provide critical contributions to river health, economic development and poverty alleviation. They ensure the continued availability of the many benefits that healthy river and groundwater systems bring to society”. Management of Environmental Flows aims to maintain the health of freshwater ecosystems
through defining and providing the specific water requirements of those freshwater species within the system. These species not only require a specific quantity and quality of water to flow, but the timing of the flow cycle may be critical for such events as spawning 120 and migration in some fish species. The biodiversity assessments conducted here provide a baseline dataset of the species found within each catchment, and information on their basic ecological requirements and life history. More detailed studies can then be focused on those species for which specific flow requirements are thought to be most critical.
One of the most challenging parts of the process is presentation of the biodiversity assessment outputs in a format which is suitable and accessible to the widest range of stakeholders. In particular, outputs need to be accessible to natural resource managers, developers and policy makers. This requires production of a range of products, including brief summaries of the issues and recommendations (policy briefs), more detailed technical reports, and comprehensive data sets. This report will serve as the detailed technical report of the assessment findings, and the full database including electronic maps for all species distributions is available. All species global assessments and distribution maps (jpegs) will be directly accessible online through the main IUCN Red List website. Regional assessments are also available from the Search Tool above. Ultimately, all species distribution maps will be accessible online.
Identification of the primary end-users of this information is also a challenge given the multitude of different organizations with overlapping and sometime contradictory jurisdiction for the management of wetland ecosystems. Preliminary efforts have been taken to identify these stakeholders through an online survey of end-user data needs but more work needs to be done in this area. The preliminary results can be found here.
In conclusion, we hope that the information provided through this assessment will be taken up by the key stakeholders in freshwater ecosystems throughout central Africa and will be integrated in the decision making processes for environmental and development planning in wetland ecosystems. In this way, we hope that the future impacts of development actions affecting inland water ecosystems can be minimized and mitigated to the benefit of freshwater species and those people who rely on freshwater species for their livelihoods and pleasure.