Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Freshwater ecosystems are highly biodiverse 1 and important for livelihoods and economic development 2 , but are under substantial stress 3.
To date, comprehensive global assessments of extinction risk have not included any speciose groups primarily living in freshwaters. Consequently, data from predominantly terrestrial tetrapods 4 , 5 are used to guide environmental policy 6 and conservation prioritization 7 , whereas recent proposals for target setting in freshwaters use abiotic factors 8 , 9 , 10 , 11 , 12 , However, there is evidence 14 , 15 , 16 , 17 that such data are insufficient to represent the needs of freshwater species and achieve biodiversity goals 18 , Here we present the results of a multi-taxon global freshwater fauna assessment for The IUCN Red List of Threatened Species covering 23, decapod crustaceans, fishes and odonates, finding that one-quarter are threatened with extinction.
Prevalent threats include pollution, dams and water extraction, agriculture and invasive species, with overharvesting also driving extinctions. We also examined the degree of surrogacy of both threatened tetrapods and freshwater abiotic factors water stress and nitrogen for threatened freshwater species. Threatened tetrapods are good surrogates when prioritizing sites to maximize rarity-weighted richness, but poorer when prioritizing based on the most range-restricted species.
However, they are much better surrogates than abiotic factors, which perform worse than random. Thus, although global priority regions identified for tetrapod conservation are broadly reflective of those for freshwater faunas, given differences in key threats and habitats, meeting the needs of tetrapods cannot be assumed sufficient to conserve freshwater species at local scales. Globally, biodiversity is in decline 6 with freshwater ecosystems being particularly affected Declines are continuing, generally out of sight and out of mind, despite the importance of the freshwater realm.
This diversity of freshwater species provides essential ecosystem services such as nutrient cycling, flood control and climate change mitigation 2 , can be used as bioindicators of wetland quality 24 , and supports the culture, economy and livelihoods of billions of people worldwide 2.
