Worldwide, shellfish aquaculture and fisheries in coastal ecosystems represent crucial activities for human feeding. But these biological productions are under the pressure of climate variability and global change. Anticipating the biological processes affected by climate hazards remains a vital objective for species conservation strategies and human activities that rely on. Within marine species, filter feeders like oysters are real key species in coastal ecosystems due to their economic and societal value (fishing and aquaculture) but also due to their ecological importance. Indeed oysters populations in good health play the role of ecosystem engineers that can give many ecosystem services at several scales: building reef habitats that contribute to biodiversity, benthic-pelagic coupling and phytoplankton bloom control through water filtration, living shorelines against coastal erosion… The Pacific oyster, Crassostrea gigas (Thunberg, 1793), which is currently widespread worldwide, was introduced into the Atlantic European coasts at the end of the 19th century for shellfish culture purposes and becomes the main marine species farmed in France (around 100 000 tons) despite severe mortalities crisis. But in the same time and because of warming, natural oysters beds has spread significantly along the French coast and are supposed to have reach approximately 500 000 tons. In that context, Pacific oyster populations (natural and cultivated) in France are the subjects of many scientific projects. Among them, a specific long-term biological monitoring focuses on the reproduction of these populations at a national scale: the VELYGER national program. With more than 8 years of weekly data at many stations in France, this field-monitoring program offers a valuable dataset for studying processes underpinning reproduction cycle of this key-species in relation to environmental parameters, water quality and climate change.   Database content: Larval concentration (number of individuals per 1.5 m3) monitored, since 2008, at several stations in six bays of the French coast (from south to north): Thau Lagoon and bays of Arcachon, Marennes Oléron, Bourgneuf, Vilaine and Brest (see map below).   Methods used to monitor larval concentration: An important volume of seawater (1.5 m3) is pumped twice a week throughout the spawning season (june-september), at one meter below the surface at high tide (+/- 2h) in several sites within each VELYGER ecosystem. Water is filtered trough plankton net fitted with 40 µm mesh. After a proper rinsing of the net, the retained material is transferred into a polyethylene bottle (1 liter) and fixed with alcohol. At laboratory, sample is then gently filtered and rinse again and transferred into eprouvette. Two sub-samples of 1 mL are then taken using a pipette and examined on a graticule slide for microscope. The microscopic examination is made with a conventional binocular optical microscope with micrometer stage at a magnification of 10 X (or above). During the counting, a special care is necessary as larvae of other bivalves are also collected and confusion is possible. Larvae of C. gigas are also classified into four stage of development: - Stage I = D-shaped straight hinge larvae (shell length <105 µm) - Stage II = Early umbo evolved larvae (shell length between 105 and 150 µm) - Stage III = Medium umbo larvae (shell length between 150 and 235 µm) - Stage IV*= Large umbo eyed pediveliger larvae (shell length > 235 µm) * Larvae that are very closed to settle are sometimes identified into a separated 5th stage, but generally this stage is included in stage IV.   Illustrations: Location of the different Velyger sites along the French coast. From south to north: Thau Lagoon and bays of Arcachon, Marennes Oléron, Bourgneuf, Vilaine and Brest.   Legend: Pacific Oyster Larvae (left side) and Natural oyster bed (right side). Photos : © S. Pouvreau/Ifremer

This database contains hauls collated from 1965 to 2019, from fisheries dependent and independent data, from across eastern Atlantic waters and French Mediterranean waters. From this data diadromous fish spatio-temporal data was cleaned and standardised.

Three saltmarshes, Aiguillon, Brouage, Fier d'Ars, located in the Pertuis-Charentais Sea along the south-west coast of France, were studied to evaluate their sediment and mass accumulation rates (SAR; MAR) based on 210Pb and 137Cs profiles in sediments. Coastal saltmarshes play indeed an essential role in providing services such as coastal protection and supporting biodiversity. Saltmarshes are also critical environments for the accumulation of sedimentary organic carbon (blue carbon). However, the number of studies on saltmarshes remains underrepresented compared to studies on mangroves and seagrass. This work is a contribution to the effort to document sediment and mass accumulation rates of saltmarshes.A total of 16 1m sediment cores were collected in the three saltmarshes (Aiguillon, Brouage, Fier d'Ars) in 2021 and 2022 using an Eijkelkamp stainless steel peat sampler. Each sediment core was sampled every 1 cm from the top to the bottom of the core. The sediment layers were used to determine dry bulk density and selected radioisotope activities (210Pb, 226Ra, 137Cs, 228Th, 137Cs). Combining excess 210Pb and 137Cs has allowed to establish a reliable chronology of sediment deposition on a multidecadal timescale.

210Pb, 226Ra and 137Cs were measured by non-destructive gamma spectrometry on marine sediment cores, collected during RIKEAU 2002 cruise on board r/v Thalia, on the shelf of the Bay of Biscay

Gironde estuary environmental parameters and SPM maps generated from 41 Landsat-8/OLI and Sentinel-2/MSI images acquired over the period 2013-2018. Except bathymetry and daily river discharge data, that are accessible on public platforms, the dataset includes all of the time seris used in the publication: Analysis of suspended sediment variability in a large highly-turbid estuary using a 5-year-long remotely-sensed data archive at high resolution, Journal of Geophysical Research: Oceans, DOI:10.1029/2019JC015417.

Data collected by the Spindrift 2 Sails of Change vessel during its attempt at the round-the-world sailing record, the Jules Verne Trophy. More information at https://spindrift-racing.com/fr/.

This dataset contains bio-optical measurements from BioGeoChemical-Argo (BGC-Argo) profiling floats complemented with ocean-colour satellite matchups of variables related to the detection of coccolithophore blooms dominated by Emiliania huxleyi. BGC-Argo float data cover the global ocean from November 2012 to December 2018 and include measurements of the particulate backscattering coefficient (BBP_float in m-1), the concentration of Chlorophyll-a (CHLA_float in mg m-3), and the particulate beam attenuation coefficient (CP_float in m-1) with data processing and quality control described in the manuscript entitled “Detection of coccolithophore blooms with BioGeoChemical-Argo floats” submitted to Geophysical Research Letters. The data represent near-surface ocean conditions, calculated as the average value in the top 15m of the water column. Daily ocean-colour satellite data were downloaded from the GlobColour project (ftp://ftp.hermes.acri.fr) with a spatial resolution of 4km and matched with every BGC-Argo float observation by using a 5x5 pixel box and a 9-day temporal window. For each float observation, we extracted concurrent satellite data of the concentrations of Particulate Inorganic Carbon (PIC_sat in mmol m-3) and Particulate Organic Carbon (POC_sat in mmol m-3), from which we derived the proportion of PIC_sat to the total particulate carbon concentration (PIC_POC_sat in % and defined as PIC_sat / [PIC_sat+POC_sat]). Coccolithophore bloom periods were identified using annual times series of PIC_sat and PIC_POC_sat at each profile location as described in the submitted manuscript, and the column “inside_coccolithophore_bloom” reports the float observations occurring inside such blooms.

These data are outputs of a spatio-temporal model inferring fish distribution. The maps are based on high-resolution catch data (VMS-logbook). They have a montly time resolution and a 0.05° spatial resolution. Four demersal species of the Bay of Biscay are available in the dataset: common sole (Solea solea), megrim (Lepidorhombus whiffiagonis), anglerfish (Lophius spp) and thornback ray (Raja clavata). Maps are provided for year 2008 to 2018 ; they were produced in the context of the MACCO project (https://www.macco.fr/en/accueil-english/), an Ifremer project that aims at proposing alternative management strategies for the mixed demersal fisheries of the Bay of Biscay.

This dataset gather isotopic ratios (carbon and nitrogen) and concentrations of mercury species (methyl and inorganic mercury) measured in several tissues (muscle, liver and gonad) for three commonly consumed fish species from the south Bay of Biscay (France) in 2017 and 2018.

The Arcachon bay is a meso- / macro-tidal (0.8 to 4.6 m), semi-enclosed lagoon of 180 km² located on the South-western coast of France. Three main water masses are described in this bay: (i) the external neritic waters (ENW) directly influenced by the adjacent oceanic waters, (ii) the intermediate neritic waters (ItNW) and (iii) the inner neritic waters (InNW) more influenced by the continental inputs. The watershed of the Arcachon bay, mainly covered by forests, has an area of 3500 km² and the bay is considered as poorly anthropised. It hosts the largest Zostera noltei seagrass meadow in western Europe and is an important site for oyster farming and Manilla clam production. Since 1997, Arcachon Bay waters are monitored for hydrological and bio-geochemical parameters by the “Environnements et Paléoenvironnements Océaniques et Continentaux” (EPOC) Research Unit of the University of Bordeaux-CNRS, first in one single station (Eyrac), then on 2 complementary sites since 2005 (Bouee13 and Comprian). The monitoring is carried out within the national framework of the “SOMLIT” (“Service d’Observation en Milieu Littoral”) which is a French multi-site monitoring network initiated in the mid-1990s. SOMLIT is based on a joint strategy for 19 sites belonging to 12 ecosystems that are distributed over the three maritime facades of mainland France, i.e. the English Channel, the Atlantic Ocean and the Mediterranean Sea. Sampling of surface water samples is performed fortnightly at high tide for a group of 15 parameters (temperature, salinity, dissolved oxygen, pH, nitrate, nitrite, ammonium, phosphate, silicate, suspended matter, chlorophyll a, concentrations and isotopic ratios of particulate organic carbon and nitrogen) and 8 flow cytometry biological variables of pico- and nanoplankton. Vertical profiles of multiparametric probes concerning 4 parameters (temperature, salinity, fluorescence, PAR) are also performed. Given the significant diversity of coastal ecosystems where SOMLIT’s stations are located, strict and joint guidelines with regards to sampling strategy, measurement methods and data qualification and storage are paramount in order to make FAIR data available to users. The whole data acquisition strategy is carried out within the framework of the SOMLIT quality system formalized in 2006-2007 by referring to the ISO 17025: 2017 standard “General requirements for the competence of testing and calibration laboratories”. Unified sampling and analysis protocols are based on recognized disciplinary standards and on the expertise of the research teams. The scientific objectives of SOMLIT are 1) to characterize the multi-decadal evolution of coastal ecosystems; 2) to determine the climatic and anthropogenic forcings and 3) to make data and logistical support available for research activities and other observation activities. SOMLIT is therefore a research tool providing large datasets that also serve as logistical support for related research actions (from seasonal to long-term studies). Two additional national networks operate at the same SOMLIT sites: “COAST-HF” network performs high-frequency measurements (automated in situ measurements every 10 to 20 minutes) and “PHYTOBS-network” provides microphytoplankton biodiversity data. SOMLIT, COAST-HF and PHYTOBS are elementary networks of the Research Infrastructure “Infrastructure Littorale et Côtière” (ILICO) and are National Observation Services (SNO) of the Institut National des Sciences de l'Univers (INSU).