Major dams and the challenge of achieving “No Net Loss” of biodiversity in the tropics

Dam construction is booming across tropical regions critical for global biodiversity and ecosystem service provision. The principle of “No Net Loss” (NNL)—under which biodiversity impacts of development projects are quantified and fully mitigated—is being increasingly applied to large infrastructure development worldwide, including dams. We discuss the impacts of major tropical dams and associated implementation of NNL policies and outline three major challenges in achieving NNL: (1) overcoming practicalities implementing NNL in highly connected river systems over large spatio‐temporal scales; (2) the stakes are high if NNL fails because tropical regions are hyper‐diverse, rich in species endemism, and difficult to restore; and (3) inclusion of ecosystem services in NNL design is necessary due to the importance of tropical biodiversity for ecosystem service provision at multiple spatial scales. Overcoming these challenges is crucial when hundreds of dams are planned and under construction across the tropics, many potentially subject to NNL policies.