One-quarter of freshwater fauna threatened with extinction
Authors: Sayer Catherine A. , Fernando Eresha , Jimenez Randall R. , Macfarlane Nicholas B. W. , Rapacciuolo Giovanni , Böhm Monika , Brooks Thomas M. , Contreras-MacBeath Topiltzin , Cox Neil A. , Harrison Ian , Hoffmann Michael , Jenkins Richard , Smith Kevin G. , Vié Jean-Christophe , Abbott John C. , Allen David J. , Allen Gerald R. , Barrios Violeta , Boudot Jean-Pierre , Carrizo Savrina F. , Charvet Patricia , Clausnitzer Viola , Congiu Leonardo , Crandall Keith A. , Cumberlidge Neil , Cuttelod Annabelle , Dalton James , Daniels Adam G. , De Grave Sammy , De Knijf Geert , Dijkstra Klaas-Douwe B. , Dow Rory A. , Freyhof Jörg , García Nieves , Gessner Joern , Getahun Abebe , Gibson Claudine , Gollock Matthew J. , Grant Michael I. , Groom Alice E. R. , Hammer Michael P. , Hammerson Geoffrey A. , Hilton-Taylor Craig , Hodgkinson Laurel , Holland Robert A. , Jabado Rima W. , Juffe Bignoli Diego , Kalkman Vincent J. , Karimov Bakhtiyor K. , Kipping Jens , Kottelat Maurice , Lalèyè Philippe A. , Larson Helen K. , Lintermans Mark , Lozano Federico , Ludwig Arne , Lyons Timothy J. , Máiz-Tomé Laura , Molur Sanjay , Ng Heok Hee , Numa Catherine , Palmer-Newton Amy F. , Pike Charlotte , Pippard Helen E. , Polaz Carla N. M. , Pollock Caroline M. , Raghavan Rajeev , Rand Peter S. , Ravelomanana Tsilavina , Reis Roberto E. , Rigby Cassandra L. , Scott Janet A. , Skelton Paul H. , Sloat Matthew R. , Snoeks Jos , Stiassny Melanie L. J. , Tan Heok Hui , Taniguchi Yoshinori , Thorstad Eva B. , Tognelli Marcelo F. , Torres Armi G. , Torres Yan , Tweddle Denis , Watanabe Katsutoshi , Westrip James R. S. , Wright Emma G. E. , Zhang E , Darwall William R. T. 
Published: January 2025

Abstract
Freshwater ecosystems are highly biodiverse1 and important for livelihoods and economic development2, but are under substantial stress3. To date, comprehensive global assessments of extinction risk have not included any speciose groups primarily living in freshwaters. Consequently, data from predominantly terrestrial tetrapods4,5 are used to guide environmental policy6 and conservation prioritization7, whereas recent proposals for target setting in freshwaters use abiotic factors8–13. However, there is evidence14–17 that such data are insufficient to represent the needs of freshwater species and achieve biodiversity goals18,19. Here we present the results of a multi-taxon global freshwater fauna assessment for The IUCN Red List of Threatened Species covering 23,496 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.