Integrating ecological niche and hydrological connectivity models to assess the impacts of hydropower plants on an endemic and imperilled freshwater turtle

Abstract

Hydropower is the main renewable energy source around the globe; however, cumulative impacts of hydropower plants (HPPs) come with vast environmental concerns. As freshwater species are susceptible to hydrodam-induced environmental modifications, an understanding of how HPPs change species distribution is required to predict and mitigate the impacts of the expansion of hydroelectric matrices generation, securing energy provision and biodiversity conservation. We assessed the impacts of HPPs on the distribution of an endemic and imperilled freshwater turtle with very unique ecological requirements, the Williams' side-necked turtle Phrynops williamsi. To prevent and mitigate impacts, we prioritized sites for species conservation by classifying planned HPP locations according to their predicted adverse effects on species distribution. We built ecological niche models to estimate the distribution of the species. Then, we contrasted the species distribution with current and planned HPPs in Brazil to (i) verify whether HPPs locations coincide with high suitability areas; (ii) assess the difference in the magnitude of impacts on species caused by HPPs regarding their licensing stage and type; and (iii) identify priority areas for species conservation over the sites where new HPPs are planned based on an integrative analysis of ecological niche and hydrological connectivity models. Finally, we assessed the risk of species extinction at multiple levels according to IUCN criteria. HPPs overlap areas of high suitability for the species, independently of type or licensing stage. Differences in adverse impacts among HPP types were determined by the affected area and the degree of disruption in connectivity. In the future, the area impacted by small HPPs will nearly equal those of large HPPs, which currently have the highest impacts on species. The conservation status of the species partially corroborated previous assessments and suggested that its extinction risk was underestimated at some levels. Synthesis and applications. Our modelling approach highlights potential conflicts between hydropower generation and species conservation. This analysis can be a complementary tool to drive decisions on the ecological sustainability of HPPs; it can reveal the patterns of cumulative impacts of HPPs on riverine species and freshwater ecosystems, informing the planning of sustainable energy provision.