To improve our knowledge of the aggregation of species around anchored FADs in Mayotte, diving surveys are carried out every 3 months on 3 FADs. Various environmental parameters are also collected in order to establish links between them and aggregations. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

This dataset consists of a quantitative imaging dataset of ZooScan-imaged mesoplankton (> 200 µm), collected with high-speed net aboard the schooner Tara during the Tara Pacific Expedition (2016-2018). Samples were collected at the surface, generally on a daily frequency, across the Atlantic and Pacific Oceans from open-ocean stations (151 samples; open-ocean label: [i00_oa###]) and from stations in coastal waters of 32 Pacific islands (54 samples; island label: [i##_oa###]). The full description and discussion of this dataset can be found in the associated data paper Mériguet et al. (in rev). This dataset consists of 256 352 plankton individuals, plankton parts, non-living particles and imaging artefacts, ranging from 300 µm to a few mm, individually imaged and measured with the ZooScan (Gorsky et al., 2010). The objects were classified into 159 taxonomic and morphological groups. All images and their taxonomic annotations are available in the open-access EcoTaxa (Picheral et al., 2017) project at this link: https://ecotaxa.obs-vlfr.fr/prj/11292. The 'EcoTaxa ZooScan Tara Pacific HSN 300 microns export' dataset contains the EcoTaxa tsv exports which associate each object with these metadata (station name, sampling coordinates, sampling date and time, etc., the main metadata are found in the Classic Metadata ZooScan Tara Pacific HSN 330 microns.csv table) and describe it by numerous morphological features extracted from each individual object by ZooProcess. The csv table named 'Export EcoTaxa ZooScan read me.csv' defines the 160 metadata and data found in the EcoTaxa tsv export. The 'Descriptors ZooScan Tara Pacific HSN 330 microns.csv' table combined the data from which we calculated quantitative descriptors of the planktonic communities: abundance (ind.m-3), biovolume (mm3.m-3; as a proxy of biomass) calculated from the area, riddled area and ellipsoidal measurement of each object (see Vandromme et al., 2012 for the 3 calculations of biovolume), and Shannon diversity index. This was done for all taxonomic annotations and for several levels of grouping; living or non-living, plankton groups and trophic association. The individual biovolumes of organisms were arranged in Normalised Biomass Size Spectra (NBSS) as described by Platt (1978), with size expressed as Equivalent Spherical Diameter (ESD, µm). NBSS calculations were made for all taxonomic annotations and for the different levels of grouping. There are available for each station in the NBSS ZooScan Tara Pacific HSN 330 microns csv tables. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

During the oceanographic surveys conducted aboard the R/V Cornide de Saavedra (Spanish Institute of Oceanography, IEO-CSIC), its continuous navigation echosounder device was integrated into the data management system in 2011. Subsequently, daily data transmission to the IEO/NODC data center continued until the conclusion of vessel activity in 2013. Following a comprehensive review of quality control and assessment, encompassing clock verification, positional data, and recorded values, the entire dataset was provided with quality flags (QF) to optimize its usability. Both the data files and QF align with seadatanet.org standards. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

The Eurofleets+ IOPD research cruise took place from 28/06/2022 till 10/07/2022 in the Uummannaq region in West Greenland where a total of five fjords and the connecting shelf area were sampled. This data upload "Data from IOPD cruise Part 2 Water sample analysis and plankton identifications" contains: -Nutrient data of NH4, NO2, NO3, NOX, PO4 and DSi. -Chlorophyll a data. -Fatty acid profiles (in relative abundance) of the microzooplankton and mesozooplankton community. At certain stations the dominant species was picked out to have a separate fatty acid profile. -Phytoplankton identifications and counts by a FlowCam. - Zooplankton identifications of MultiNet samples by microscopy. A maximum of 10 specimen per species, per net, per sampling station were measured. - Zooplankton identifications of the Video Plankton Recorder data, accompanied with depth, temperature, salinity, turbidity, and fluorescence data from the CTD and FLNTU sensors mounted on the VPR. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

Although zooplankton was extensively studied in the North Sea, knowledge about winter zooplankton assemblages is still scarce, despite potential influence of zooplankton overwintering stocks on seasonal plankton succession and productivity. Furthermore, several economically and ecologically important fish species reproduce during winter contributing to the zooplankton community as passive members (eggs) or predators (larvae). To shed some light on winter zooplankton distribution, abundance and composition in the Southern North Sea and Eastern English Channel, we defined assemblages based on mesozoo- and ichthyoplankton data sampled between January and February 2008 using fuzzy-clustering and indicator species. Mesozoo- and ichthyoplankton (eggs+larvae) were integrated in a common analysis by using a spatial grid adapted to the datasets and defined by means of a geostatistical method developed in agronomics. Potential environmental drivers of assemblage distribution were evaluated by means of GLMM and comparison with data from 2022 facilitated insight about the inter-annual representativeness of the assemblages. Five zooplankton assemblages were found varying with regard to total zooplankton abundance, dominant and indicator taxa. Spatial variability of abiotic (dissolved nutrients, salinity, depth, temperature, organic matter in suspension, chlorophyll a), biotic variables (phyto- and microplankton composition), water masses and fish spawning grounds were revealed as potential drivers of assemblage distribution. Assemblages off the Rhine-Scheldt estuary and in the German Bight harbored the biggest zooplankton overwintering stocks that might influence the grazing pressure on phytoplankton spring production. Assemblages off the Rhine-Scheldt estuary and covering the English Channel and the Southern Bight were found to be of high importance for herring and plaice larvae. Although further analyses suggested inter-annual representativeness of the assemblages found (2008 vs 2022), the assessment of further years would be necessary to account for potential inter-annual variability. Future studies could profit from the assessment of microzooplankton facilitating insight in fish larvae feeding potential and zooplankton overwintering strategies. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

The ARCHYD dataset, which have been collected since 1988, represents the longest long-term hydrologic data sets in Arcachon Bay. The objectives of this monitoring programme are to assess the influence of oceanic and continental inputs on the water quality of the bay and their implications on biological processes. It also aims to estimate the effectiveness of management policies in the bay by providing information on trends and/or shifts in pressure, state, and impact variables. Sampling is carried on stations spread across the entire bay, but since 1988, the number and location of stations have changed slightly to better take into account the gradient of ocean and continental inputs. In 2005, the ARCHYD network was reduced to 8 stations that are still sampled by Ifremer to date. All the stations are sampled at a weekly frequency, at midday, alternately around the low spring tide and the high neap tide. Data are complementary to REPHY dataset. Physico-chemical measures include temperature, salinity, turbidity, suspended matters (organic, mineral), dissolved oxygen and dissolved inorganic nutrients (ammonium, nitrite+nitrate, phosphate, silicate). Biological measures include pigment proxies of phytoplankton biomass and state (chlorophyll a and phaeopigment). Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

The ReZoEnv field campaign was conducted at 9 sites distributed within contrasted seagrass (Zostera notlei) meadows in the Arcachon Bay. This multi-parameter survey was conducted during one year (November 2015 – November 2016). Water levels, temperature and light were recorded every 10 minutes. While bed sediment characteristics (granulometry, water content, organic matter content), seagrass characteristics (coverage, biometry, chlorophyll and CNP content) were measured monthly. Additionally, wind-wave parameters were obtained from high frequency pressure sensor at 4 sites, every 20 minutes. List of sites : ANDE : 44.745091 N, 1.121366 O FONT : 44.722631 N, 1.080133 O GAIL : 44.662573 N, 1.099575 O GARR : 44.705132 N, 1.121562 O HAUT : 44.729331 N, 1.15608 O ILE : 44.683117 N, 1.162716 O JACQ : 44.724563 N, 1.181109 O PASS : 44.689927 N, 1.089491 O ROCH : 44.648529 N, 1.127736 O Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

MARLEY (Monitoring deep-seA coRaL EcosYstems) is a deep seafloor observing system dedicated to the monitoring of cold-water coral habitats. The system is deployed in the Lampaul canyon off Brittany, France since August 2021 and maintained each year during the ChEReef-Obs cruises. The study site is a coral garden dominated by Madrepora oculata, located on a sedimented platform at 780 m depth. MARLEY is equipped with a CTD SBE 37-SIP, an oxygen optode Aanderaa (4330 or 4831), an ADCP Teledyne RDI Workhorse 300kHz, a turbidity sensor Wetlabs ECO NTU (sensitivity: 0-1000 NTU), a sediment trap Technicap PPS 4/3 – 24 bottles and a camera module. The camera module, which can be moved from up to 30 m from the main station, is equipped with a camera AXIS Q1786, two flash lights and a fluorometer & scattering meter SEA-BIRD ECO FLNTU. All sensors are controlled and synchronised by the Communication and Storage Front-end - 2nd generation (COSTOF2), which is also managing data storage. Optical sensors are protected from fouling by electrochlorination (20 seconds, each 6 hours). The oxygen optode is calibrated each year prior to deployment. These datasets provide raw data from the oxygen optode Aandera 4831, the CTD Seabird SBE37, the Wetlabs ECO NTU and the SEAR-BIRD ECO FLNTU covering the period 28/08/2021 to 19/01/2022, with a frequency of 15 minutes. Data from Wetlabs ECO NTU include raw counts and Nephelometric Turbidity Unit (NTU) derived from manufacturer’s calibration with Scale Factor = 0.0611 and Dark Counts = 50. Data form SEABIRD ECO FLNTU include raw counts at 695 nm (Chlorophyll) and 700 nm (Turbidity). Chlorophyll concentration (µg/l) is derived from manufacturer’s calibration with Scale Factor = 0.0180 and Dark Counts = 48. Nephelometric Turbidity Unit (NTU) is derived from manufacturer’s calibration with Scale Factor = 0.0481 and Dark Counts = 50. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

This dataset contains current data acquired between September 2016 and July 2017 using 2 TCM3 Ocean Bottom Tilt Current Meters installed next to the Tour Eiffel and Montségur hydrothermal vent sites. The TCM-3 Ocean Bottom Tilt Current Meter from Lowell Instruments LLC (North Falmouth, MA, USA) measures current using the drag-tilt principle. The logger is buoyant and is anchored to the bottom via a short flexible tether. Drag from moving water tilts the logger in the direction of flow. The logger’s accelerometer and magnetometer channels are used to record the amount of tilt and direction of tilt (compass bearing). The array comprised 3 currentmeters, deployed near the Tour Eiffel, Montségur and White Castle hydrothermal vent sites (the instrument at White Castle did not recover data). The array is not connected to an energy node. The currentmeter's internal clocks are set to UTC time before deployment. Clock drift after recovery is not implemented in data but added as metadata in the file "Sites and Sensor metadata". Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

Approximately 25% of Antarctic Bottom Water has its origin as dense water exiting the western Ross Sea, but little is known about what controls the release of dense water plumes from the Drygalski Trough. We deployed two moorings on the slope from February, 2018, to January, 2019, to investigate the water properties of the bottom water exiting the region at Cape Adare and the relationship with the seasonal cycle, winds, and tides. Mooring P2 was placed at 1750 metres depth on the slope at Cape Adare at the same location as an earlier deployment of mooring CA1 in the CALM experiment (Gordon et al., 2015). Instruments on P2 were placed at the same depths as CA1 to continue that time series. Mooring P3 was placed on the same isobath on the slope at the mouth of the Drygalski Trough to measure the water properties moving along the slope from the east. Findings from the observations are described in Bowen et al. (2021). Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.