When waters rise: Biodiversity potentially affected on a major flooding in Southern Brazil

Southern South America is projected to experience increased heavy rainfall due to global climate change. These extremes events should be more common and affect negatively both human well-being and biodiversity. Here, we studied the effects of the massive flooding in May 2024 on biodiversity. We showed that 4,300 km² of native ecosystems were inundated, including 1,200 km² of forests and 1,020 km² of grasslands. Aquatic ecosystems, wetlands, and costal vegetation on sandy soils were also affected. Flooding affected 825 km² of an insufficiently Protected Area (PA) network, impacting 17% of areas designated for sustainable use and 26% of strictly PAs. Similarly, 1,440 km² of Permanent Preservation Areas (PPAs) were flooded, with 67% already lacking native vegetation. The flooding potentially affected 747 tetrapod species, including 84 threatened species, with amphibians and reptiles exhibiting the highest percentage of distribution affected. Threatened species were disproportionately affected by the flooding, especially amphibians, reptiles, and mammals. Therefore, restoration efforts, especially in PAs and PPAs, are critical to safeguard ecosystems and human communities in a world of rapid changes. Tetrapod species with reduced mobility, small-ranged species and threatened species should also be prioritized.