A quarter of freshwater wildlife is threatened with extinction

A quarter (24%) of freshwater wildlife, including crustaceans, fish and insects, face a “high risk of extinction” due to “considerable pressures” such as pollution, dams or agriculture intensive activity that affects their habitat, concludes a study in “Nature” on Wednesday.

Fresh waters, including rivers, lakes or wetlands, are home to more than 10% of known species, including around a third of vertebrates and half of fish, although they represent less than 1% of the surface of the world. Earth.

This biodiversity is both very rich and very fragile, while it represents an important issue for the livelihoods and economic development of “billions of people around the world”, as well as a factor in mitigating the effects of climate change, emphasize the authors of the study.

Endangered decapods and tetrapods

Among the 23,496 species studied, the threat is particularly significant for decapods (shrimp, crayfish, crabs, etc.), 30% of which risk becoming extinct, but freshwater fish, tetrapods (frogs, salamanders, reptiles but also birds and mammals) and odonates (dragonflies) are also endangered, with respectively 26%, 23% and 16% of their species which are at risk of extinction.

89 freshwater species have already been confirmed as extinct since 1500, and 178 others are suspected of being extinct.

“There is an urgent need to act quickly if we do not want others to decline or disappear in turn,” warn the authors of the study, calling for “changes in practices in the management” of fresh water, taking take biodiversity into greater account.

Underestimated figures

These figures could be underestimated because, for a certain number (23%) of these species, information remains insufficient, specifies the study, which was based on the database and methodology of the red list of species. threatened by the International Union for Conservation of Nature (IUCN).

The dangers are diverse: 54% of threatened species are affected by pollution, 39% by dams and water extraction, 37% by land use change and associated effects of agriculture, and 28 % by invasive species and diseases.

Nearly a fifth of threatened freshwater species also suffer from climate change and severe weather events.

84% of spaces threatened

Most threatened species (84%) are affected by more than one threat.

This decline “continues, generally off the radar”, while the state of wetlands, 35% of which have already disappeared between 1970 and 2015, continues to deteriorate.

Of those that still exist, 65% face moderate to high threats and 37% of rivers of more than 1000 km see their natural courses hampered, underlines the study, deploring that freshwater ecosystems have “until now ‘recently not been given as much priority as marine and terrestrial environments’ in research.

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