Biodiversity responses to hydroelectric reservoir management

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Hydrological modifications to lakes and rivers are a pervasive form of environmental change in Quebec and around the world. While there are clear social benefits to regulate aquatic ecosystems (e.g. flood control, hydroelectricity), the ecological impacts are less clear and represent issues that local communities in Quebec are wrestling with. In particular, winter water level drawdowns are a common practice in north temperate reservoirs, but ecological research on this topic is limited. In partnership with QCBS and local community groups, we have conducted a synthesis of the literature as well as a field survey of reservoirs. Our research has shown that many juvenile and adult fish populations show a surge in abundance following reservoir creation but fish communities as a whole appear to be unaffected by the level of water level drawdown. In contrast, high macroinvertebrate abundances tend to only occur in nearshore sites if they are not exposed by drawdown, suggesting that benthic resources for fish could be limiting. We are now evaluating whether fish growth and diets are altered by water level drawdown. Check out the video made by FQRNT and Canal Savoir covering our preliminary findings. See video here.