Christophe Brabant, Laura J. Pollock, Lars Lonsmann Iversen
Mapping threats to the world’s freshwater biodiversity
Earth has entered an era of unparalleled human activities, resulting in dramatic biodiversity loss worldwide. Nowhere is this more true than in freshwater ecosystems, which are both the richest habitats on Earth as well as the most threatened globally. Anthropogenic pressures in freshwater ecosystems have been extensively studied, yet effective conservation action remains limited by the lack of information on the geographical patterns and when these pressures translate into threats to freshwater species. Here, we use comprehensive data from the International Union for the Conservation of Nature to map the impact of 45 threats to all assessed freshwater amphibians, reptiles, fish, mammals, dragonflies, and molluscs. Our results highlight the most acute overlap of threats’ impact to freshwater species occurring in Europe and Northern Africa. Crops and their water-borne pollutants stand out as the major threat to freshwater biodiversity globally, both in their average impact across watersheds and their global coverage. Additionally, in a given watershed, we find an association between the intensity of the impact of threats and the extinction risk of the species present. Our assessment reports global evidence of the far-reaching and dramatic impacts of anthropogenic activities, revealing a much more drastic impact of threats on freshwater biodiversity compared to their terrestrial counterparts. Our results provide the baseline knowledge for future mitigation actions and conservation initiative in freshwater systems. A baseline urgently needed in order to support sustainable planning for various domains of human activities and assist in setting conservation priorities for watersheds at risk.
