Transient biodiversity and food web responses in regulated aquatic ecosystems

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Large dams are a pervasive feature of the landscape around the globe, particularly because hydropower is being upheld as an opportunity to decarbonise our global economy. However, this should not be to the detriment of biodiversity and ecosystem functions. The long-term objectives of my research program are to understand the ecological processes underlying the stability and the resilience of aquatic communities in regulated rivers and reservoirs, and use this knowledge to predict the sustainability of these socio-ecological systems. Over the last few years, I have made critical transdisciplinary contributions to the study of biodiversity, aquatic productivity and food web processes in reservoirs. Over the next five years, I will advance our understanding of multitrophic biodiversity, food web interactions, and species network in regulated aquatic ecosystems, as well as interactions between ecological and biogeochemical processes with the goal of addressing how the dynamics and ecosystem functions of reservoirs change through time, and differ relative to natural ecosystems. Through a combination of time series analyses, modelling, lab and field studies, and syntheses, I will apply a multitrophic biodiversity lens and a cross-ecosystem approach to quantify how dams can influence food webs. We will also use a multidisciplinary approach and link ecology to biogeochemistry, with the goal of explaining the transient dynamics in reservoirs. More specifically, I will (1) examine the differences in multitrophic biodiversity between regulated and natural aquatic ecosystems over time and space, (2) evaluate the impacts of drawdown on terrestrial subsidies' inputs, uptake and food web, (3) link ecological and biogeochemical processes to understand the transient dynamics of ecosystems services and functions in regulated aquatic ecosystems. This program will result in the multidisciplinary training of two PhD students, one PDF and at least four BSc students in aquatic ecology and biodiversity science with expertise in field work, stable isotopes analyses, and sophisticated statistical methods (ecological network and structural equation modelling). In Canada and especially in Quebec, hydropower represents respectively 63% and 97% of our energy production and is a cornerstone of our economy. Our national strategy for GHG targets is also strongly linked to hydropower generation. It is thus essential to develop knowledge of the impacts of dams and reservoirs on aquatic communities through time and space to understand the processes by which aquatic communities adapt or not to the new conditions encountered in reservoirs. This conceptual framework can assist managers and scientists in developing expectations about the costs, benefits, and trade-offs of balancing ecosystem services provided by dams and biodiversity.