A study published Thursday in Science maps global threats to freshwater biodiversity across more than 21,000 species, identifying 45 types of threats that endanger vertebrate life in ecosystems covering less than 4% of Earth's surface but hosting nearly a third of the planet's vertebrate species.
Biologist Christophe Brabant of McGill University in Montreal led the research. The team found that freshwater species face higher threat impacts than species restricted to terrestrial environments, on average. Most threats stem from human activity.
Geographic analysis reveals distinct regional patterns. In South America, agriculture and aquaculture pose the greatest risks. In the eastern United States, residential and commercial development combines with excess human emissions. Europe and northwest Africa face the most acute pressure. Europe experiences pollution from urban, agricultural, and industrial sources, while northwest Africa confronts pollution, damming, and intensive water use combined. In less populated regions like Siberia and northern Canada, threat levels were comparatively mild.
Specific species illustrate the pressures. The critically endangered European eel confronts threats from urbanization and pollution. The fire salamander struggles with manmade habitat destruction and competition from invasive species, compounded by agricultural activity.
Brabant told Courthouse News that the 2022 Kunming-Montreal Global Biodiversity Framework establishes commitments to reduce pollution, manage agriculture sustainably, and conserve and restore ecosystems. He noted that COP17, currently taking place in Armenia, marks the first global review of progress implementing that framework.
Conservation requires local action coordinated across river basins, Brabant said. Approaches include working with farmers to reduce fertilizer and pesticide runoff, restoring riverbank vegetation, protecting wetlands, adjusting dam operations to maintain seasonal flows, protecting connected habitats, and removing obsolete barriers. Brabant stressed that decisions about land use must consider long-term effects on freshwater ecosystems and the people who depend on them.