Description du projet
Cartographie du rôle des diazotrophes dans le cycle du carbone
Les micro-organismes diazotrophiques favorisent la régulation de la productivité marine de la planète en convertissant l’azote et en contribuant aux puits de carbone. On ignore toutefois la quantité de carbone dérivé des diazotrophes qui est exportée vers le fond des océans. Le projet HOPE, financé par l’UE, cherche à le découvrir, ce qui permettra d’obtenir de meilleures prévisions sur le rôle de l’océan dans la séquestration du CO2 et l’atténuation du changement climatique. Les chercheurs emploieront des techniques isotopiques unicellulaires pour examiner cette pompe à carbone procaryote afin de cartographier ses caractéristiques transitoires et saisonnières. Une colonne d’eau expérimentale permettra également aux chercheurs de déterminer la manière dont les diazotrophes se regroupent, coulent et sont reminéralisés, et une plateforme de mesure autonome surveillera la manière dont les facteurs environnementaux contrôlent l’efficacité de la pompe. Cette approche génèrera de nouvelles estimations mondiales du carbone exporté par les diazotrophes.
Objectif
Diazotrophs regulate marine productivity in 60% of our oceans by alleviating nitrogen limitation, contributing to carbon (C) sequestration through the N2-primed Prokaryotic C Pump (PCP). Yet we don’t know how much diazotroph-derived organic C (OC) is exported to the deep ocean, which prevents robust predictions of how the ocean contributes to CO2 sequestration and climate change mitigation. This knowledge gap is due to the multiple and complex pathways by which diazotrophs are exported to the deep ocean, which quantification and drivers of variability are impossible to capture with current methods. HOPE will bridge this gap thanks to a new isotopic technique I developed and to a coupling between lab and in situ approaches examining processes occurring at different spatiotemporal scales, and capable of capturing both transient and seasonal features of the PCP. HOPE will: 1.Determine how various diazotrophs aggregate, sink and are remineralized by using an automated experimental water column I designed for this proposal 2.Decipher by which pathways diazotroph-derived OC is exported to the deep ocean thanks to a pioneer approach combining single-cell isotopic analyses, in-depth microbiological characterization of sinking particles and geochemical budgets 3.Investigate how environmental drivers control the whole process, from the surface diazotroph community up to their eventual export to the deep ocean, by deploying a cutting-edge autonomous platform, unique as it performs synoptic measurements both in and below the euphotic zone at high resolution (hourly/daily). In its final stage, HOPE will use the generated data to provide global, spatially resolved estimates of the contribution of diazotrophs to overall OC export. Based on my expertise at the interface between microbial oceanography and geochemistry, HOPE has the potential to deliver a multidisciplinary and ground-breaking knowledge leading to potential scientific-based recommendations to fight climate change.
Champ scientifique
- natural sciencesearth and related environmental sciencesgeochemistry
- social scienceseconomics and businesseconomicsproduction economicsproductivity
- natural sciencesbiological sciencesecologyecosystems
- natural sciencesearth and related environmental sciencesoceanography
- natural sciencesearth and related environmental sciencesatmospheric sciencesclimatologyclimatic changes
Programme(s)
- HORIZON.1.1 - European Research Council (ERC) Main Programme
Régime de financement
HORIZON-AG - HORIZON Action Grant Budget-BasedInstitution d’accueil
13572 Marseille
France