Enhancing The Conservation Of Freshwater Biodiversity Through Improved Freshwater Conservation Planning Techniques

ABSTRACT Nel, J.L. 2008. Enhancing the conservation of freshwater biodiversity through improved freshwater conservation planning techniques. PhD thesis, University of Cape Town. Freshwater ecosystems and biota are among the most endangered in the world. This current situation is even more disturbing when future threats of escalating human demand and global climate change are considered. Urgent measures are therefore needed to conserve freshwater ecosystems and sustain the services they provide. These may take the form of formal protection but also need to include less restrictive mechanisms, such as implementing integrated catchment management and environmental water requirements. Systematic conservation planning provides a strategic and scientifically defensible framework for doing this. Pioneered in the terrestrial realm, uptake of systematic conservation planning for freshwater ecosystems has been slow. While broad principles are applicable, approaches need to be freshwaterspecific. The lack of freshwater-specific frameworks and tools is a key factor hampering the application of systematic conservation planning in the freshwater realm. The aim of this thesis was to address this need by developing a suite of frameworks and practical applications for planning in freshwater settings. The development of a framework for the rapid assessment of river ecosystem endangerment and protection levels provided a common currency for comparing the state of biodiversity across terrestrial and aquatic realms. It showed, for the first time, that the state of river ecosystems in South Africa is dire, far worse than that of terrestrial ecosystems. In addition, river ecosystems have very low levels of representation in protected areas, with many not represented at all. A more optimistic finding was that river systems in protected areas appear to be in a better overall condition than those outside of protected areas, emphasizing the potential of protected areas in conserving freshwater ecosystems. Currently, however, protected area systems worldwide show significant gaps in their conservation of freshwater biodiversity. A framework was therefore developed for locating and designing protected area systems for the benefit of river biodiversity. Conservation objectives were established for improving river biodiversity pattern and processes in both new and existing protected areas. These included representation of river ecosystems and freshwater fish species, representation of large-scale biodiversity Abstract ii processes associated with free-flowing rivers and catchment-estuarine linkages, and improving the persistence of river reaches already contained within protected areas. Data were collated in a Geographic Information System (GIS) and a conservation planning algorithm was used as a means of integrating the multiple objectives in a spatially efficient manner. Realistically, protected areas can only play a partial role in overall efforts to conserve freshwater biodiversity and need to be supplemented with other off-reserve conservation strategies. In addition, conservation strategies that focus only on representation of biodiversity in isolated areas are conceptually flawed, especially given the inherent connectivity of freshwater ecosystems. Such conservation strategies need to be augmented with approaches that address the persistence of freshwater biodiversity. A framework for planning for the persistence of freshwater biodiversity was therefore developed, synthesizing concepts from freshwater ecology and terrestrial conservation planning. When considering issues of persistence, making use of a multiple-use zoning strategy is a practical option because it helps to emphasize that different levels of protection, and hence utilization, can be afforded to different conservation areas. This helps to strengthen the linkages between people and conservation, and aligns more closely with planning categories used by water resource managers and land use planners. Planning for both representation and persistence should be achieved simultaneously to maximize spatial efficiency. Several methods of planning for representation and persistence were explored. An existing conservation planning algorithm (MARXAN) was adapted for use in freshwater settings through the incorporation of directional connectivity considerations. When using a conservation planning algorithm, the manner in which spatial efficiency between persistence and representation is achieved depends on whether or not a multiple-use zoning strategy will be applied during design. Given the practicalities of multiple-use zoning at local levels of planning, it is recommended that zones should be used in the design phase, rather than merely allocated at the end once the design is complete. In summary, research and practice in conservation has tended to focus on terrestrial biodiversity; while water resources management has tended to have a more utilitarian focus. It is high time to elevate freshwater biodiversity concerns on the agendas of both these sectors. By developing common conservation frameworks around which the water and conservation sector can engage and debate, this thesis attempts to enhance the integration of freshwater biodiversity concerns into both these sectors.