Empirical characterization factors to be used in LCA and assessing the effects of hydropower on fish richness

Total characterization factor estimates (CF) and their 95% CI for boreal (in blue), temperate (in green) and tropical reservoirs (in orange). A negative value represents a gain of species and a positive value a loss of species. The black dots represent the reservoirs used in this study. [Display omitted] •First empirically based characterization factors for fish biodiversity in LCA;•Extensive literature search to extract rate of change in fish richness;•Development of characterization factors for hydropower from three biomes;•High impact of hydropower in the tropics, lower impacts in temperate & boreal regions;•Hydropower can decarbonize our economy but at higher ecological cost in the tropics. Hydropower is often presented as a clean, reliable, and renewable energy source, but is also recognized for its potential impacts on aquatic ecosystem biodiversity. We used direct empirical data of change in fish species richness following impoundment to develop ecological indicators to be used in Life Cycle Assessment (LCA), and accounting for hydropower impacts on aquatic ecosystems. Data were collected on 89 sampling stations (63 stations located upstream, and 26 located downstream of a dam) distributed in 26 reservoirs from three biomes (boreal, temperate and tropical). Overall, the impact of hydropower on fish species richness was significant in the tropics, of smaller amplitude in temperate biome and minimal in boreal biome, stressing the need for regionalisation when developing indicators. The impact of hydropower was consistent across scales for a given biome (same directionality and statistical significance across sampling stations and reservoirs). However, the indicators were sensitive to the duration of the study (the period over which data have been collected after impoundment), which can underestimate the impacts. This result highlights the need to account for the duration of the transient dynamics to reach a steady state (rate of change in species richness = 0) before developing ecological indicators. By using the LCA approach, our suggested indicators contribute to fill a major gap in assisting decision-makers when evaluating the potential of alternative energy technologies, such as hydropower, to decarbonize the worldwide economy, while minimizing the impacts on aquatic ecosystems.