Conservation of freshwater biodiversity in Oriental Asia: constraints, conflicts, and challenges to science and sustainability

Abstract

Freshwater ecosystems in Asia are under grave threat. Large and growing human populations and the rapid pace of development have led to the degradation of natural environments throughout the region. Conservation of freshwater biodiversity faces particular challenges because of a lack of public awareness of its magnitude and importance. Even taxa with high public-relations value, such as fishes, are rather poorly known, and the variety of other animals associated with lakes and riverine wetlands, including charismatic and endangered megafauna, seems to have escaped wide attention. The rate and extent of environmental change in Asia are having impacts on the aquatic biota that may be greater than anywhere else on the planet. Particular threats include water pollution, from point and nonpoint sources, which is almost ubiquitous; overharvest of fishes, turtles, and crocodilians; flow regulation and impoundment of rivers; as well as drainage basin degradation and climate change. Many lakes have been so modified by human activities that they function as enormous fishponds, and the introduction of exotic species (especially, but not only, fishes) or the translocation of native taxa has contributed to the extinction of endemic species in isolated drainage basins. The prognosis is grim, and we can anticipate a loss in biodiversity and homogenization of the regional biota. Reversal of these trends will require a change in focus by limnologists and water-resource managers, and the urgent adoption of a conservation agenda for freshwater science in Asia.