A5035468677- Marine and coastal ecosystems
- Marine Biology and Ecology Research
- Historical Studies and Socio-cultural Analysis
- Ocean Acidification Effects and Responses
- Microbial Community Ecology and Physiology
- Oceanographic and Atmospheric Processes
- European Political History Analysis
- Atmospheric and Environmental Gas Dynamics
- Methane Hydrates and Related Phenomena
- Diverse Cultural and Historical Studies
- Polish Historical and Cultural Studies
- Isotope Analysis in Ecology
- Arctic and Antarctic ice dynamics
- Multiculturalism, Politics, Migration, Gender
- Religious Tourism and Spaces
- Theology and Canon Law Studies
- Geology and Paleoclimatology Research
- Global Energy and Sustainability Research
- Medieval European Literature and History
- Aquatic Ecosystems and Phytoplankton Dynamics
- Protist diversity and phylogeny
- Historical and Religious Studies of Rome
- Geochemistry and Elemental Analysis
- French Historical and Cultural Studies
- Oil Spill Detection and Mitigation
Aix-Marseille Université
2018-2024
Centre National de la Recherche Scientifique
2011-2024
Institut de Recherche pour le Développement
2011-2024
Université de Bretagne Occidentale
2011-2024
Université de Toulon
2019-2024
Ifremer
2022-2024
Laboratoire des Sciences de l'Environnement Marin
2011-2024
Institut Français
2024
Institut Méditerranéen d’Océanologie
2018-2023
Institut Universitaire Européen de la Mer
2011-2023
Particulate organic carbon (POC) generated by primary production and exported to depth, is an important pathway for transfer the abyss, where it stored over climatically significant timescales. These processes constitute biological pump. A spectrum of particulate sinking velocities exists throughout water column, however numerical models often simplify this into suspended, fast slow particles. Observational studies suggest speeds in ocean strongly bimodal with >85% POC flux contained...
The dynamics of the particulate organic carbon (POC) pool in ocean are central to marine cycle. POC is link between surface primary production, deep ocean, and sediments. rate at which degraded dark can impact atmospheric CO2 concentration. Therefore, a focus geochemistry studies improve our understanding distribution, composition, cycling. last few decades have seen improvements analytical techniques that greatly expanded what we measure, both terms compound structural diversity isotopic...
Abstract The export of organic carbon from the surface ocean forms basis biological pump, an important planetary flux. Typically, only a small fraction primary productivity (PP) is exported (quantified as efficiency: export/PP). Here we assemble global data synthesis to reveal that very high efficiency occasionally occurs. These events drive apparent inverse relationship between PP and efficiency, which opposite typically used in empirical or mechanistic models. At scale, find low PP,...
The oceanic biological carbon pump (BCP) regulates the Earth cycle by transporting part of photosynthetically fixed CO2 into deep ocean. Suppressing this mechanism would result in an important increase atmospheric level. BCP occurs mainly form (1) organic (OC) particles sinking out surface ocean, (2) neutrally buoyant OC (dissolved or particulate) entrained downward water masses movements and/or mixing, and (3) active transport migrating animals such as zooplankton fishes. These various...
Abstract The ocean contributes to regulating atmospheric CO 2 levels, partly via variability in the fraction of primary production (PP) which is exported out surface layer (i.e., e ratio). Southern Ocean studies have found that contrary global‐scale analyses, an inverse relationship exists between ratio and PP. This remains unexplained, with potential hypotheses being (i) large export dissolved organic carbon (DOC) high PP areas, (ii) strong microbial recycling regions, and/or (iii)...
Iron is an essential nutrient that regulates productivity in ~30% of the ocean. Compared with deep (>2000 meter) hydrothermal activity at mid-ocean ridges provide iron to ocean's interior, shallow (<500 fluids are likely influence surface's ecosystem. However, their effect unknown. In this work, we show emitted along Tonga volcanic arc (South Pacific) have a substantial impact on concentrations photic layer through vertical diffusion. This enrichment stimulates biological activity, resulting...
Abstract The transfer of photosynthetically produced organic carbon from surface to mesopelagic waters draws dioxide the atmosphere 1 . However, current observation-based estimates disagree on strength this biological pump (BCP) 2 Earth system models (ESMs) also exhibit a large spread BCP estimates, indicating limited representations known export pathways 3 Here we use several decades hydrographic observations produce top-down estimate with an inverse biogeochemical model that implicitly...
Abstract. The oceanic biological carbon pump is an important factor in the global cycle. Organic exported from surface ocean mainly form of settling particles derived plankton production upper layers ocean. large variability current estimates strength emphasises that our knowledge a major planetary flux remains poorly constrained. We present database 723 organic export 234Th technique. dataset archived on data repository PANGEA® (www.pangea.de) under doi:10.1594/PANGAEA.809717. Data were...
Marine phytoplankton growth at high latitudes is extensively limited by iron availability. Icebergs are a vector transporting the bioessential micronutrient into polar oceans. Therefore, increasing iceberg fluxes due to global warming have potential increase marine productivity and carbon export, creating negative climate feedback. However, magnitude of flux, subsequent fertilization effect resultant export not been quantified. Using analysis samples, we reveal that concentrations vary over...
Abstract Numerical simulations of ocean biogeochemical cycles need to adequately represent particle sinking velocities (SV). For decades, Stokes' Law estimating SV from density and size has been widely used. But while holds for small, smooth, rigid spheres settling at low Reynolds number, it fails when applied marine aggregates complex in shape, structure, composition. Minerals zooplankton can alter phytoplankton ways that change their SV, potentially improving the applicability models....
Abstract Arctic primary production is sensitive to reductions in sea ice cover, and will likely increase into the future. Whether this increased (PP) translate export of particulate organic carbon (POC) currently unclear. Here we report on POC efficiency during summer 2012 Atlantic sector Ocean. We coupled 234‐thorium based estimates flux onboard incubation‐based PP. Export (defined as fraction PP that exported below 100 m depth: ThE ‐ratio) showed large variability (0.09 ± 0.19–1.3 0.3)....
Abstract The vertical flux of marine snow particles significantly reduces atmospheric carbon dioxide concentration. In the mesopelagic zone, a large proportion organic carried by sinking dissipates thereby escaping long term sequestration. Particle associated prokaryotes are largely responsible for such loss. However, links between this important ecosystem and ecological processes as community development on different particle fractions (sinking vs. non-sinking) yet virtually unknown. This...
Abstract Diazotrophs are widespread microorganisms that alleviate nitrogen limitation in 60% of our oceans, thereby regulating marine productivity. Yet, the group-specific contribution diazotrophs to organic matter export has not been quantified, which so far impeded an accurate assessment their impact on biological carbon pump. Here, we examine fate five groups globally-distributed by using original combination mesopelagic particle sampling devices across subtropical South Pacific Ocean. We...
Abstract Upwelling ocean currents associated with oxygen minimum zones (OMZs) supply nutrients fuelling intense marine productivity. Perturbations in the extent and intensity of OMZs are projected future, but it is currently uncertain how this will impact fluxes redox‐sensitive trace metal micronutrients to surface ocean. Here we report seawater concentrations Fe, Mn, Co, Cd, Ni alongside redox indicator iodide/iodate Peruvian OMZ during 2015 El Niño event. The drove atypical upwelling...
Correlations between particulate organic carbon (POC) and mineral fluxes in the deep ocean have inspired inclusion of "ballast effect" parameterizations cycle models. A recent study demonstrated regional variability effect ballast minerals on flux POC ocean. We undertaken a similar analysis shallow export data from Arctic, Atlantic, Southern Oceans. Mineral ballasting is greatest importance high-latitude North where 60% associated with minerals. This fraction drops to around 40% Ocean. The...
The role of biominerals in driving carbon export from the surface ocean is unclear. We compiled particulate organic (POC), and mineral ballast fluxes 55 different locations Atlantic Southern Oceans. Substantial POC accompanied by negligible was recorded implying that association with phases not a precondition for to occur. proportion non‐mineral associated sinking ranged 0 80% highest areas previously shown be dominated diatoms. This consistent previous estimates showing transfer efficiency...
Abstract The ocean's potential to export carbon depth partly depends on the fraction of primary production (PP) sinking out euphotic zone (i.e., e ‐ratio). Measurements PP and flux are often performed simultaneously in field, although there is a temporal delay between those parameters. Thus, resulting ‐ratio estimates incorrectly assume an instantaneous downward flux. Evaluating results from four mesocosm studies, we find that peaks organic matter sedimentation lag chlorophyll by 2 15 days....
Abstract. In the ocean, sinking of particulate organic matter (POM) drives carbon export from euphotic zone and supplies nutrition to mesopelagic communities, feeding degradation activities which in turn lead flux attenuation. Oxygen (O2) minimum zones (OMZs) with suboxic water layers (< 5 µmol O2 kg−1) show a lower attenuation compared well-oxygenated waters (> 100 kg−1), supposedly due reduced heterotrophic activity. This study focuses on particle fluxes through hypoxic 60 kg−1);...
In marine oxygen (O2) minimum zones (OMZs), the transfer of particulate organic carbon (POC) to depth via biological pump might be enhanced as a result slower remineralisation under lower dissolved O2 concentrations (DO). parallel, nitrogen (N) loss atmosphere through microbial processes, such denitrification and anammox, is directly linked (PN) export. However it unclear (1) whether DO only factor that potentially enhances POC in OMZs, (2) if particle fluxes are sufficient support observed...
High mercury (Hg) levels have been observed for arctic biota, despite limited local sources of anthropogenic Hg in the Arctic. Scavenging exerts an important control on residence time surface waters. The downward export flux and burial rates bottom sediments are not well-constrained as a result lack particulate (Hgp) observations Arctic Ocean. Here, we estimated based concentrations suspended matter (SPM) using radionuclide pair 234Th/238U, coupled to Hgp/234Th ratios particles. Using new...
Abstract. The ocean's biological carbon pump (BCP) plays a major role in the global cycle. A fraction of photosynthetically fixed organic produced surface waters is exported below sunlit layer as settling particles (e.g., marine snow). Since seminal works on BCP, estimates strength BCP have improved but large uncertainties remain (from 5 to 20 Gt C yr−1 euphotic zone or mixed-layer depth). 234Th technique widely used measure downward export particulate (POC). This has advantage allowing flux...