New freshwater ecosystem atlas
How many and which rivers and wetlands do we have to maintain in a natural condition to sustain economic and social development, while still conserving our freshwater biodiversity?
The answer to this question is illustrated in an atlas that was introduced in November 2011 by the deputy minister of water and environmental affairs, Ms Rejoice Mabudafhasi. The atlas is the result of a project that started three years ago and contains mapped river, wetland and estuary priorities for South Africa.
The project partners included the South African National Biodiversity Institute (SANBI), the Council for Scientific and Industrial Research (CSIR), the Water Research Commission (WRC), the World Wide Fund for Nature - South Africa (WWF), the Department of Water Affairs and the Department of Environmental Affairs, the South African Institute for Aquatic Biodiversity (SAIAB) and the South African National Parks (SANParks).
Project leader and CSIR principal scientist, Dr Jeanne Nel, says water influences the well-being of a country's people; water shortages or a decline in water quality will hamper economic development. Ultimately, she adds, the quantity, quality and timing of water flow are determined by the health of the ecosystems through which the water flows.
The 2004 National Biodiversity Assessment highlighted the shocking state of river ecosystems in South Africa, with 84% of ecosystems associated with South Africa's large rivers being critically endangered, endangered or vulnerable. While this study explored main rivers, the 2011 National Biodiversity Assessment took smaller tributaries into account. This assessment was less pessimistic but still found that over half of South Africa's river ecosystems are threatened.
The starting point for the work was agreeing on criteria for priority areas. The project used data from the national river health programme as well as from a multitude of river surveys and assessments, some of which were coordinated by the then Department of Water Affairs and Forestry. The research team also sourced data from the different provincial structures in the various water management areas. These data sets were then put into a spatial format and were once again taken to freshwater ecologists and biodiversity experts at regional review workshops.
"The atlas content summarises the data and on-the-ground knowledge of the freshwater ecological community in South Africa, representing over 1 000 person years of collective experience. The collaborative spirit of the freshwater scientific community in South Africa has been one of the biggest success factors of the project," says Driver. Dr Harry Biggs, Program Integrator: Adaptive Biodiversity Outcomes at SANParks says: "The evaluation of an expert who has been in the field for years, is incredibly important."
Dr Ernst Swartz, senior scientist at SAIAB, believes the project will make a difference in the conservation of freshwater fishes in South Africa. "For the first time, freshwater fish experts around the country prioritised threatened fish species and their surviving populations on a national scale. The maps we produced are a benchmark for future conservation planning and represent a significant step towards prioritising our efforts to prevent extinction of our unique freshwater fish fauna."
Some of the key findings that emerged once the data had been collected and processed, include:
- Overall, tributaries are in a far better state than mainstream rivers and they offer excellent conservation opportunities. They also support the sustainability of hard-working rivers further downstream by diluting poor water quality and 'flushing' pollutants. Only 35% of the length of South Africa's mainstream rivers is in a good condition, compared to 57% of the tributaries.
- Some 57% of river ecosystems and 65% of wetland ecosystems are threatened. The high levels of threat result particularly from intense land pressures, especially around cities.
- By treating less than a quarter (22%) of our rivers as priority areas, South Africa will be able to conserve natural examples of its diverse freshwater ecosystems while contributing to sustainable development of water resources in the country.
- South Africa has only 62 free-flowing rivers, which constitute only 4% of our river length. Free-flowing rivers have become a very rare feature in the South African landscape and the few representative examples must be kept free-flowing.
- The priority areas identified in the atlas protect over 50 threatened fish species. Many of these fishes are on the brink of extinction, but by managing a very small proportion of our rivers, this can be avoided.
19 Priority Area Maps
The atlas contains 19 priority area maps: one for each water management area in South Africa. The maps show river priority areas and the associated land that drains into that particular river reach, called the sub-catchment. It also shows wetlands, or clusters of wetlands that are priorities. It has different colour fish symbols to indicate the presence of a fish sanctuary for critically endangered and endangered and other threatened indigenous freshwater fish. Upstream management areas are also indicated: in these areas development can go ahead, but must not impact on the condition of the downstream priority areas.
The atlas is also available on DVD with a GIS viewer. The project team has compiled an implementation manual to provide guidance on how the freshwater ecosystem priority areas should be implemented.