- Associate professor in oceanography, specialist in the control of the biogeochemical cycle of carbon by hydrodynamics in a context of global changeedit
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The PHYTOBS dataset includes long-term time series on marine microphytoplankton, since 1987, along the whole French metropolitan coast. Microphytoplankton data cover microscopic taxonomic identifications and counts. The whole dataset is... more
The PHYTOBS dataset includes long-term time series on marine microphytoplankton, since 1987, along the whole French metropolitan coast. Microphytoplankton data cover microscopic taxonomic identifications and counts. The whole dataset is available, it includes 25 sampling locations. PHYTOBS network studies microphytoplankton diversity in the hydrological context along French coasts under gradients of anthropogenic pressures. PHYTOBS network allows to analyse the responses of phytoplankton communities to environmental changes, to assess the quality of the coastal environment through indicators, to define ecological niches, to detect variations in bloom phenology, and to support any scientific question by providing data. The PHYTOBS network provides the scientific community and stakeholders with validated and qualified data, in order to improve knowledge regarding biomass, abundance and composition of marine microphytoplankton in coastal and lagoon waters in their hydrological context....
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IntroductionWhile crucial to ensuring the production of accurate and high-quality data—and to avoid erroneous conclusions—data quality control (QC) in environmental monitoring datasets is still poorly documented.MethodsWith a focus on... more
IntroductionWhile crucial to ensuring the production of accurate and high-quality data—and to avoid erroneous conclusions—data quality control (QC) in environmental monitoring datasets is still poorly documented.MethodsWith a focus on annual inter-laboratory comparison (ILC) exercises performed in the context of the French coastal monitoring SOMLIT network, we share here a pragmatic approach to QC, which allows the calculation of systematic and random errors, measurement uncertainty, and individual performance. After an overview of the different QC actions applied to fulfill requirements for quality and competence, we report equipment, accommodation, design of the ILC exercises, and statistical methodology specially adapted to small environmental networks (<20 laboratories) and multivariate datasets. Finally, the expanded uncertainty of measurement for 20 environmental variables routinely measured by SOMLIT from discrete sampling—including Essential Ocean Variables—is provided.Re...
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Knowledge of the relative contributions of phytoplankton size classes to zooplankton biomass is necessary to understand food‐web functioning and response to climate change. During the Deep Water formation Experiment (DEWEX), conducted in... more
Knowledge of the relative contributions of phytoplankton size classes to zooplankton biomass is necessary to understand food‐web functioning and response to climate change. During the Deep Water formation Experiment (DEWEX), conducted in the north‐west Mediterranean Sea in winter (February) and spring (April) of 2013, we investigated phytoplankton‐zooplankton trophic links in contrasting oligotrophic and eutrophic conditions. Size fractionated particulate matter (pico‐POM, nano‐POM, and micro‐POM) and zooplankton (64 to >4000 μm) composition and carbon and nitrogen stable isotope ratios were measured inside and outside the nutrient‐rich deep convection zone in the central Liguro‐Provencal basin. In winter, phytoplankton biomass was low (0.28 mg m−3) and evenly spread among picophytoplankton, nanophytoplankton, and microphytoplankton. Using an isotope mixing model, we estimated average contributions to zooplankton biomass by pico‐POM, nano‐POM, and micro‐POM of 28, 59, and 15%, re...
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Research Interests: Earth Sciences, Environmental Science, Oceanography, Multivariate Statistics, Biology, and 15 moreCapillary electrophoresis, Biological Sciences, Mediterranean Sea, Environmental Sciences, Biogeosciences, Community Structure, Bacterioplankton, Dissolved Organic Carbon, Marine Systems, Mediterranean Climate, Multivariate Statistical Analysis, Environmental Parameter, Microbial community, Driving force, and Environmental factor
Research Interests: Earth Sciences, Geology, Oceanography, Biological Sciences, Transport, and 15 moreCoastal fisheries, Variability, Impact, Sediment, Efficiency, Continental shelf, Bottom Trawling, Sea, Particulate Matter, Mediterranean Climate, Consequences, Trawling, Sediment Resuspension, Suspended Particulate Matter, and gulf of lion
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A multi-element biogeochemical model forced by a 1 km resolution hydrodynamical model was used to gain in understanding of the biogeochemical functioning of the North-Western Mediterranean (NW Med), the only region in the whole... more
A multi-element biogeochemical model forced by a 1 km resolution hydrodynamical model was used to gain in understanding of the biogeochemical functioning of the North-Western Mediterranean (NW Med), the only region in the whole Mediterranean Sea with a marked and recurrent spring bloom behavior related to the winter dense water formation characterizing this area. After an assessment of the simulation using satellite derived chlorophyll and Dewex project in situ nutrients observations, the nitrogen and phosphorus seasonal cycles were analyzed using model outputs on the period 2012-2013. Injections of nutrients during the wind intensification period allow the triggering of the autumn bloom. Then, convection in winter upwells large amounts of nutrients in the euphotic layer. When the conditions for phytoplankton development are gathered (reduction of vertical mixing, low grazing pressure), a bloom is triggered with a massive consumption of nutrients during more than one month resulting at the end of April in a depletion of nutrients at the surface. Nutrients consumption continues to deplete nutrients at increasing depth, increasing the nutriclines and deep chlorophyll maximum depths. That finally leads to the summer oligotrophy of the water column. Then a quantification of nitrogen and phosphorus budgets of the open-sea convection area was performed on an annual basis. The deep convection area represents a sink of nitrate and phosphate, and a source of organic nitrogen and phosphorus for the peripheric regions. Regarding the biogeochemical nitrogen cycle, the deep-nitrate based new production is responsible for 19% of the total nitrogen uptake. This new production dominates during the winter deep convection and spring bloom periods. Finally, our results suggest that the NW Med open sea convection represents a major source of nutrients for the Mediterranean surface sea.
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Research Interests: Chemistry, Kinetics, Carbon, Aquatic Toxicology, Environmental Chemistry, and 15 moreMedicine, Multidisciplinary, Identification, Bacteria, Nitrates, Herbicide, Dissolved organic matter, Herbicides, First Order Logic, Aquatic environment, Active Ingredient, Aqueous Solution, Hydrolysis, Molecular Structure, and Heterotrophic Bacteria
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Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainWe performed a multi-parameter monitoring during 14 months from February 2013 through April 2014 in a... more
Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainWe performed a multi-parameter monitoring during 14 months from February 2013 through April 2014 in a coastal station (NW Mediterranean). We studied the temporal variability of dissolved organic matter (DOC) in relation to changes in abiotic and biotic variables. The production of fluorescent dissolved organic matter (FDOM) peaked in winter, and the highest concentrations of FDOM humic-like compounds coincided with decreases of salinity, indicating a notable fresh-water contribution to the organic matter pool. The significant linear relationship between humic-like FDOM peak and Silicate concentration (r2=0.72 n=60 p <0.05) also reveals the importance of ground water inputs in the quality of dissolved organic matter. DOC concentrations showed its maxima in late spring and summer (probably because of a low bacterial activity associated to nutrient limitation). These DOC maxima in warm periods did not coincide with the FDOM peaks maxima as we could anticipate due to the photolability of FDOM compounds. We discuss the relative importance of bacterial activity, light conditions and fresh water inputs on FDOM temporal variabilityPeer Reviewe
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. Total alkalinity (AT) and total dissolved inorganic carbon (CT) in the oceans are important properties to understand the ocean carbon cycle and its link with climate change (ocean carbon sinks and sources) or global change (ocean... more
. Total alkalinity (AT) and total dissolved inorganic carbon (CT) in the oceans are important properties to understand the ocean carbon cycle and its link with climate change (ocean carbon sinks and sources) or global change (ocean acidification). We present a data-base of more than 44 400 AT and CT observations in various ocean regions obtained since 1993 mainly in the frame of French projects. This includes both surface and water columns data acquired in open oceans, coastal zones and in the Mediterranean Sea and either from time-series or punctual cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ± 4 µmol kg-1 for both AT and CT. Given the lack of observations in the Indian and Southern Oceans, we added sea surface underway AT and CT data obtained in 1998–2018 in the frame of OISO cruises and in 2019 during the CLIM-EPARSES cruise measured onboard using the same technique. Separate datasets for the global ocean, and for the Mediterranean Sea are provided in a single format (https://doi.org/10.17882/95414, Metzl et al., 2023) that offers a direct use for regional or global purposes, e.g. AT/Salinity relationships, long-term CT estimates, constraint and validation of diagnostics CT-AT reconstructed fields or ocean carbon and coupled climate/carbon models simulations, as well as data derived from BG-ARGO floats. When associated with other properties, these data can also be used to calculate pH, fugacity of CO2 (fCO2) and other carbon systems properties to derive ocean acidification rates or air-sea CO2 fluxes.
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The Tara Microplastics mission was conducted for 7 months to investigate plastic pollution along nine major rivers in Europe—Thames, Elbe, Rhine, Seine, Loire, Garonne, Ebro, Rhone, and Tiber. An extensive suite of sampling protocols was... more
The Tara Microplastics mission was conducted for 7 months to investigate plastic pollution along nine major rivers in Europe—Thames, Elbe, Rhine, Seine, Loire, Garonne, Ebro, Rhone, and Tiber. An extensive suite of sampling protocols was applied at four to five sites on each river along a salinity gradient from the sea and the outer estuary to downstream and upstream of the first heavily populated city. Biophysicochemical parameters including salinity, temperature, irradiance, particulate matter, large and small microplastics (MPs) concentration and composition, prokaryote and microeukaryote richness, and diversity on MPs and in the surrounding waters were routinely measured onboard the French research vessel Tara or from a semi-rigid boat in shallow waters. In addition, macroplastic and microplastic concentrations and composition were determined on river banks and beaches. Finally, cages containing either pristine pieces of plastics in the form of films or granules, and others cont...
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The Tara Pacific expedition (2016-2018) sampled coral ecosystems around 32 islands in the Pacific Ocean and the ocean surface waters at 249 locations, resulting in the collection of nearly 58,000 samples. The expedition was designed to... more
The Tara Pacific expedition (2016-2018) sampled coral ecosystems around 32 islands in the Pacific Ocean and the ocean surface waters at 249 locations, resulting in the collection of nearly 58,000 samples. The expedition was designed to systematically study warm coral reefs and included the collection of corals, fish, plankton, and seawater samples for advanced biogeochemical, molecular, and imaging analysis. Here we provide a complete description of the sampling methodology, and we explain how to explore and access the different datasets generated by the expedition. Environmental context data were obtained from taxonomic registries, gazetteers, almanacs, climatologies, operational biogeochemical models, and satellite observations. The quality of the different environmental measures has been validated not only by various quality control steps but also through a global analysis allowing the comparison with known environmental large-scale structures. Such a wide released datasets opens...
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Pieter van Beek (1), Joseph Tamborski (1,2), Simon Bejannin (1), Marc Souhaut (1), Thomas Stieglitz (3), Olivier Radakovitch (3,4), Christelle Claude (3), Jordi Garcia-Orellana (5), Marc Diego-Feliu (5), Christophe Monnin (6), Charlène... more
Pieter van Beek (1), Joseph Tamborski (1,2), Simon Bejannin (1), Marc Souhaut (1), Thomas Stieglitz (3), Olivier Radakovitch (3,4), Christelle Claude (3), Jordi Garcia-Orellana (5), Marc Diego-Feliu (5), Christophe Monnin (6), Charlène Odobel (7), Mireille Pujo-Pay (7), Pascal Conan (7), Jean-François Ghiglione (7), Olivier Crispi (7), Mariia Petrova (8), Lars-Eric Heimbürger (8), Jean-Luc Seidel (9), François Lacan (1), Céline Charbonnier (10), and the MED-SGD
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Biomass, inorganic carbon and nitrogen uptake, ammonium regeneration, nitrification, and vertical flux of particulate matter were measured in the equatorial Pacific at 21 daily productivity stations occupied on a meridional transect... more
Biomass, inorganic carbon and nitrogen uptake, ammonium regeneration, nitrification, and vertical flux of particulate matter were measured in the equatorial Pacific at 21 daily productivity stations occupied on a meridional transect (150°W) between 1°N and 16°S. Three areas could be distinguished along the transect: (1) the equatorial area between 1°N and 6°S, where nitrate concentrations were typically eutrophic, reaching up to 3 μg‐at L−1 in surface waters; (2) an intermediate mesotrophic area between 6° and 10°S, where surface nitrate concentrations decreased from 1 μg‐at L−1 to zero; and (3) the oligotrophic area beyond 10°S, characterized by warm and nitrate poor waters. Although nitrate was the main form of inorganic nitrogen available for phytoplankton growth (70%–100% of total), its uptake was severely retarded in the equatorial sector. This lack of nitrate depletion in the equatorial sector between 0 and 6°S may in part result from the important ammonium supply (100 ng‐at L...