Thousands of freshwater species are threatened with extinction

Thousands of freshwater species worldwide are threatened with extinction. This is reported by a research group led by the International Union for Conservation of Nature (IUCN) in the journal Nature. The team analyzed data on more than 20,000 species – and the results warn of a massive loss of biodiversity in rivers, lakes and other freshwater habitats.

Decapods in particular are threatened

When it comes to the loss of biodiversity, the focus is often on dramatic insect deaths, starving polar bears or bleaching corals. The research group led by Catherine Sayer from the IUCN has now assessed the extinction risk of freshwater wildlife. Fresh water includes rivers, lakes, karst and other springs as well as oases and provides habitat for more than ten percent of all known species.

Numerous species of fish, crabs and dragonflies lived in and around such waters – their risk of extinction has so far been neglected. To change that, the research group analyzed data on almost 23,500 species on the IUCN Red List and also identified their biggest threats.

The result: Around 24 percent of these freshwater animals are at high risk of extinction. Broken down by group, decapods (Decapoda), which include crabs, crabs and shrimps, are particularly at risk – 30 percent of the species examined are threatened with extinction. For freshwater fish it is 26 percent, for odonates, i.e. dragonflies and dragonflies, 16 percent.

In addition, 89 species have been documented to be extinct since the year 1500 and 178 species are presumed extinct, according to the study. 11 species are therefore only found in captivity and no longer in the wild. In view of this, “urgent action must be taken to prevent further species declines and losses,” write the researchers.

No more excuses for inaction

Looking at the causes, the scientists found that 54 percent of the threatened species examined would be affected by environmental pollution, 39 percent by dams and water extraction and 37 percent by land use changes and the associated effects of agriculture, for example. Invasive species and diseases are responsible for the threat in 28 percent. Some species are threatened by several causes at the same time. For fish, the research group points to the impairment caused by overfishing and also dams, which block migration routes.

Overall, their analysis makes it clear that something urgently needs to be done about these threats in order to prevent further decline and loss of species, the authors warn: “The lack of data on the status and distribution of biological diversity in freshwater no longer serve as an excuse for inaction.”