Assessment Process

The combined data sets for freshwater fishes, molluscs, plants (selected taxa), crabs and odonates are analysed here to present a synthesis of the status and distribution of some key components of freshwater biodiversity. For some analyses we have included additional information on freshwater dependent mammals (as defined on the IUCN Red List), freshwater turtles, amphibians, and waterbirds for which regional data sets also exist. The objective is to provide outputs of use in conservation planning for wetlands ecosystems and wetland species at the regional, national, and site scales. The combined data sets also provide a regional-scale knowledge base to enable the integration of freshwater biodiversity considerations within environmental and development planning throughout the region.

Selection of priority taxa

In the majority of cases, large-scale biodiversity assessments have focused on a limited range of taxonomic groups, most often including those groups providing obvious benefits to humans through direct consumption, or the more charismatic groups such as the mammals and birds. In the case of aquatic systems, it is the wetland birds and fish that have received most attention. It is, however, important that we take a more holistic approach by collating information to conserve those other components of the foodweb essential to the maintenance of healthy functioning wetland ecosystems, even if they are neither charismatic nor often noticed (especially submerged species). It is not practical to assess all species, so a number of priority taxonomic groups were selected to represent a range of trophic levels within the foodwebs that underlie and support wetland ecosystems. Priority groups were selected to include those taxa for which there was thought to be a reasonable level of pre-existing information. The taxonomic groups selected were: fishes; molluscs; odonates (dragonflies and damselflies); crabs and aquatic plants.

Although fishes provide a clear benefit to the livelihoods of many people throughout the region, either as a source of income or as a valuable food source, benefits provided by the other taxa may be indirect and poorly appreciated but nonetheless are most important. Given the wide range of trophic levels and ecological roles encompassed within these five taxonomic groups, information on their distributions and conservation status, when combined, will provide a useful indication of the overall status of the associated wetland ecosystems.