A global analysis of fish biodiversity using environmental DNA (eDNA) has shown that warmer climates amplify biodiversity as river catchments grow larger, while human activity dampens this effect. The research, led by the University of Zurich, Eawag, and Yunnan University, published its findings in Nature Ecology & Evolution.
The study underscores how climate and anthropogenic pressures interact to reshape freshwater ecosystems. In warmer regions, larger rivers naturally accumulate more species, but this relationship weakens where human impact is high, suggesting development and pollution alter natural biodiversity patterns.
Researchers collected eDNA from hundreds of river sites globally, detecting species without capturing fish. They found that catchment size explains more biodiversity variation in tropical than in temperate zones, but human disturbance reduces this spatial pattern significantly.
The findings highlight a need for region-specific conservation strategies. As global temperatures rise, tropical rivers could become biodiversity hotspots, but only if human pressures like dam building and runoff are managed. The team called for integrating eDNA monitoring into policy.
The approach offers a faster, cost-effective way to assess river health, though eDNA cannot distinguish recent from historical presence. This limitation means some detected species may no longer inhabit the sampled reaches.