Hydropower dams and reservoirs and their impacts on Brazil's biodiversity and natural habitats: A Review

Much of the electric energy produced within the extensive territory of Brazil (8,511,000 km²) comes from large and small reservoirs built to produce hydroelectric power, which flood large natural areas, negatively impacting regional biodiversity. Huge reservoirs originating from Amazon river dams, such as Balbina (2,360 km², with 26,000 wild animals rescued), in the 1970s, and Tucuruí (2,430 km², 284,000 animals rescued, including more than 19,000 howler monkeys), in the 1980s, caused huge losses of natural forest habitats and the consequent decimation of wild fauna. After being rescued, wild animals were released in neighboring areas, whose territories and spaces were already occupied by local animals. In the face of competitive exclusion or because of the principle of xenophobia, these displaced animals ended up dead or experienced truly little success. As well as causing the loss of regional biodiversity, the reservoir creates a vacuum in the previously continuous environment, causing habitat fragmentation. In addition to the Amazon biome, other rivers in different biomes, such as the Pantanal, have also been threatened with the proliferation of dams. There, the hydrological regime influences nutrient cycling, ecological community, phenology, upstream migration of fish and other factors. Fish migrate to the headwaters for spawning behavior that takes place at the headwaters. If they encounter obstacles, such as hydroelectric dams, the migration is interrupted. This review aims to assess the effects on biodiversity of major hydroelectric plants, with their dams and reservoirs, and discusses viable proposals for damage mitigation, environmental compensation, and biodiversity conservation actions