Conservation of Aquatic Ecosystems

Freshwaters are among the most biodiverse ecosystems on Earth, and on average their species are also the most imperiled. Although data are often poor, there is evidence that large numbers of freshwater fishes, amphibians, mammals, reptiles, and species from many macroinvertebrate groups are at risk of extinction. Major categories of threats are habitat degradation, water pollution, flow modification, species invasion, overexploitation, and climate change. Stresses to freshwaters, derived both from activities on the terrestrial landscape and direct modifications to freshwater systems, are typically multiple and overlapping in effect. Conservation of freshwaters faces many challenges related to data gaps, the position of freshwaters within larger landscapes, the connected nature of many freshwater systems, and the demand for water resources by numerous user groups. Traditional conservation strategies designed to protect terrestrial species and habitat are typically insufficient for freshwaters; strategies must be tailored to the distinctive features of freshwaters and will have to be developed and applied within the context of integrated basin management to ensure that threats are mitigated and critical ecosystem processes, often linked to hydrology, can function within natural ranges of variation.