A dancing jewel damselfly (Platycypha caligata) rests on waterside vegetation. Dragonflies and damselflies depend on both freshwater and the surrounding landscape, leaving them vulnerable to changes on land. The new study shows that agricultural expansion and intensification are the dominant threat across nearly a third of their global range. Credit: Lars L. Iversen

Farming, dams and agricultural runoff are the biggest threats to freshwater biodiversity globally, with Europe and Northwest Africa the hardest-hit regions, McGill researchers have found.

Applying a mapping methodology previously used to study terrestrial species, the researchers identified where freshwater species are under threat, and which human activity seems to be responsible.

"The Global Geography of Threats to Freshwater Biodiversity" is published in Science .

Their study could help conservationists prioritize where interventions are most urgently needed, they said.

"At a time when global biodiversity frameworks risk overlooking…