Jumeaux numériques des systèmes socio-écologiques dans les systèmes de courants de bord Est : incertitudes et mécanismes de l'impact du changement climatique sur les ressources marines du Chili central

Eastern Boundary Upwelling Systems (EBUS), such as the Humboldt Current System off Chile, are among the most productive marine ecosystems in the world and support valuable fisheries and coastal communities. They are particularly exposed to climate change and interacting stressors, including ocean warming, deoxygenation, and acidification. These stressors can interact in complex and nonlinear ways, affecting circulation, habitat availability, trophic interactions, species distributions, and marine-resource biomass. Yet major uncertainties remain in translating regional environmental changes into ecosystem and resource responses, partly because climate, biogeochemical, ecological, and socio-economic processes are traditionally studied separately. This PhD will develop an integrated digital twin of the Northern/Central Chilean coastal ecosystem to bridge these domains and trace climate signals from ocean dynamics and biogeochemistry through ecosystem processes to marine-resource responses and management. The framework will couple the regional ocean model CROCO, its biogeochemical component BioEBUS, and Atlantis, a state-of-the-art deterministic, whole-of-ecosystem, end-to-end model integrating biophysical, ecological, economic, and social components. This approach will provide a process-based representation of the physical–biogeochemical–ecosystem cascade, enabling uncertainty propagation into ecosystem and biomass projections and the development of the first ensemble of regional projections of marine-resource dynamics for this highly productive region. The research has three interconnected objectives. First, the PhD will develop, calibrate, and validate an Atlantis model for Northern/Central Chile and quantify how uncertainty from natural ocean variability, initial conditions, and ecosystem parameters propagates through the digital twin. Second, it will use extreme climate events, particularly El Niño, as storylines to investigate mechanisms linking physical and biogeochemical changes to trophic dynamics and marine-resource responses, with emphasis on nonlinear responses, ecological memory, hysteresis, and recovery. Third, the digital twin will be driven by regional climate projections to generate ensemble trajectories of bentho-pelagic ecosystem dynamics under different levels of global warming. These simulations will identify thresholds and potential regime shifts and enable controlled “what-if” experiments comparing alternative fisheries pressures and management strategies. The project will combine advanced numerical modelling, high-performance computing, ecological diagnostics, and uncertainty quantification. Particular emphasis will be placed on distinguishing robust climate-driven ecosystem responses from uncertainty arising from natural variability and model formulation, while identifying mechanisms underlying changes in biomass, trophic structure, and ecosystem function. The PhD will be conducted within an international collaborative environment involving CSIRO in Australia, the University of Toulouse/CECI-CERFACS, and the Universidad de Concepción, and will benefit from the CLAP and SAFESEA programmes under the auspices of the United Nations Decade of Ocean Science for Sustainable Development. Beyond its regional focus, the project will provide a benchmark framework for integrated climate–ecosystem projections in other Eastern Boundary Upwelling Systems. Its outcomes will support climate-resilient marine-resource management by linking environmental change to ecosystem and fisheries responses and informing science-based adaptation strategies. Overall, the project will train the next generation of researchers in the tools, concepts, and interdisciplinary skills needed to address complex sustainability challenges and advance integrated environmental and socio-ecological sciences. École doctorale : SDU2E - Sciences de l'Univers, de l'Environnement et de l'Espace Direction : Boris DEWITTE Financement : MSCA COFUND BEST