A systematic map of hydropower impacts on megafauna at the land-water interface

Hydropower plants have been developed globally to provide renewable energy, increase water supply and help with flood control. Meanwhile, hydropower impacts on riverscape and aquatic species are widely documented. However, little attention has been paid to impacts on large semi-aquatic animals such as crocodylians, turtles, and otters, which are prone to environmental changes associated with hydropower development. We conducted a systematic mapping of evidence documented in the published literature and synthesised the effects of hydropower development on semi-aquatic megafauna (i.e., semi-aquatic animals with a reported maximum body mass ≥ 30 kg). We identified 68 relevant impact records from 30 studies, which demonstrated that hydropower plants profoundly altered the habitats of semi-aquatic megafauna and affected their interactions with humans and domestic animals. Hydropower plants posed adverse impacts on the distribution, fitness, movement, nutrition, and reproduction of semi-aquatic megafauna. Positive impacts, such as increased suitable habitats and available food resources associated with land cover change, were also observed in some instances. Our study reveals a considerable information gap on effects of hydropower development at the land-water interface and underscores the gaps in current assessments, such as the lack of monitoring schemes that compare the situations of semi-aquatic species before and after dam construction. It also emphasises priority regions for monitoring and conservation schemes, particularly in tropic regions that are experiencing rapid hydropower development. We highlight the need to incorporate hydropower impacts on semi-aquatic animals into planning and management of renewable energy infrastructure for better informed decisions on energy production and biodiversity conservation.