A global study of freshwater species has found nearly a quarter are threatened with extinction, with scientists calling for the findings to be used to help reduce the loss of freshwater biodiversity.

James Cook University’s Dr Michael Grant was a co-author of the study published in the journal Nature this week, which looked at how more than 23,000 freshwater species around the world are faring.

“It included 23,496 fishes, decapod crustaceans (such as crabs, crayfishes and shrimps) and odonates (such as dragon flies and damsel flies).

“Overall, 24% of these species are at high risk of extinction, with decapods having the highest percentage of species threatened - 30%, as compared to 26% for freshwater fishes and 16% for odonates,” said Dr Grant.

He said the most dangerous threats are pollution, dams, water extraction, agriculture and invasive species, with overharvesting also driving extinctions.

“Among the studied species, 54% of threatened species are considered to be affected by pollution, 39% by dams and water extraction, 37% by land use change and associated effects from agriculture and 28% by invasive species and disease,” said Dr Grant.

He said biodiversity is in decline globally with freshwater ecosystems being particularly affected, but assessments of freshwater fishes and invertebrates has received comparatively little investment, political will or attention, including from the mainstream conservation community.

“It seems like a case of out of sight, out of mind,” said Dr Grant.

He said the findings of the analysis could help to reduce the loss of freshwater biodiversity if they were integrated into conservation management and government policy.

“Given that around one-quarter of freshwater species are at high risk of extinction, we need to act quickly if we want to prevent further species declines and losses,” said Dr Grant.