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.

水力发电通常被视为一种清洁，可靠和可再生的能源，但也因其对水生生态系统生物多样性的潜在影响而得到认可。我们利用水库蓄水后鱼类物种丰富度变化的直接经验数据来开发用于生命周期评估（LCA）的生态指标，并考虑水电对水生生态系统的影响。从分布在三个生物群落（北方，温带和热带）的26个水库中的89个采样站（63个位于大坝的上游，26个位于大坝的下游）收集了数据。总体而言，水电对热带地区鱼类物种丰富度的影响是显着的，温带生物群落的幅度较小，而北方生物群落的幅度最小，因此在制定指标时需要进行区域化。对于给定的生物群落，水电的影响在各个尺度上都是一致的（在采样站和水库之间，方向性和统计意义相同）。但是，指标对研究的持续时间（蓄水后收集数据的时间段）很敏感，这可能会低估影响。该结果突出表明，在制定生态指标之前，需要考虑瞬态动力学持续到稳定状态的持续时间（物种丰富度的变化率= 0）。通过使用LCA方法，我们建议的指标有助于弥补在协助决策者评估水电等替代能源技术使世界经济脱碳的潜力同时最大程度地减少对水生生态系统的影响方面的重大空白。