French Research Institute for Exploitation of the Sea
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Influence of seawater treatment by ultrafiltration and culture conditions on the biochemical composition of the diatom Odontella aurita
No full textMicroalgae synthesized several biologically active substances. Their rapid growth rate and cellular plasticity in response to changing culture conditions renders microalgae a virtually inexhaustible resource with considerable industrial potential. However, the utilisation of this resource at industrial scale is subject to several constraints, both biological and technical, including contamination and predation, as well as the difficulty of processing very large volumes of water. This study ascertains the impact of culture conditions on the growth and biochemical composition of the marine diatom Odontella aurita and more especially the water treatment by ultrafiltration. Based on an original approach by an experimental design, results are presented to evaluate the impact of the culture parameters through a quantitative and qualitative analyzes on biomass concentration and microalgae growth in terms of the productivity, the dry weight composition and the cell composition. For the first time, a study shows that the seawater ultrafiltration process, utilized as a seawater treatment for microalgae cultivation, exerted a substantial influence on the growth dynamics of the culture, leading to an average increase in cell concentration of 47.5 % compared to cultures in chlorinated seawater. Additionally, the impact of this process on the biochemical composition of the biomass was noteworthy, as it leaded to an improvement in overall productivity (an augmentation x 1.76 of dry mass production) and a shift toward enhanced protein and carbohydrate production. Ultrafiltration resulted in a biochemical profile of the algal biomass that was composed mainly of proteins, carbohydrates and pigments. In contrast, the use of chlorinated water favours the proportion of lipids and minerals
Conformal taxonomic validation: A semi-automated validation framework for citizen science records
No full textCitizen science records are a valuable source of marine biodiversity data, especially where standardized sampling campaigns are limited in spatial or temporal scope. However, such records often contain biases and errors and typically require expert validation before they can reliably support scientific research. Validating large volumes of citizen science data remains an important challenge. In this paper, we present a semi-automated validation framework that combines a deep learning classifier with conformal prediction to generate sets of plausible taxonomic labels at multiple ranks, while providing rigorous control over prediction confidence. Extensive evaluation was carried out using 25,000 jellyfish records, both with and without prior validation, as well as against 800 expert-validated entries. Our results show that the method frequently produces singleton prediction sets that can be accepted automatically, offering a high-confidence and scalable solution for validating marine citizen science data
Recommendations to Heads of State and Government from the International Scientific Committee of the One Ocean Science Congress, Nice, 3-6 June 2025
No full textScientific research plays a pivotal role in supporting decision-makers to address global ocean challenges, including the impacts of and solutions to climate change, biodiversity loss, and environmental degradation. This involves delivering clear, evidence-based guidance that integrates Indigenous knowledge and diverse value systems. At this critical juncture for our planet, a close interaction between scientists and decision-makers to advocate for science-driven policies that promote long-term ocean sustainability, engage the public, foster inclusivity, and stimulate innovation through interdisciplinary research. Grounded in scientific insights, we provide 10 thematic recommendations aligned with the Ocean Action Panels to shape discussions at the 2025 United Nations Ocean Conferenc
Omics to Study and Manage Aquatic Environments: A Snapshot From the AquaEcOmics Meeting (Evian‐les‐Bains, 2025)
No full textThe AquaEcOmics meeting brought together 280 scientists applying omics tools to aquatic research in March 2025 (Evian‐les‐Bains, France). We synthesised here the main outcomes from the 167 presentations which were given. A similar number of presentations were about micro‐ and macroorganisms. While studies on macroorganisms mostly focused on stakeholder‐driven research and methodology development, studies on microorganisms tended to focus on fundamental scientific questions. These questions mostly contributed to community ecology studies using metabarcoding; functional ecology studies using metagenomics, metatranscriptomics and metabolomics; and to a lesser degree population genomics studies using metabarcoding and RADseq, ddRADseq. Stakeholder‐driven research presentations could be clustered in two groups: those using omics to replace existing standardised monitoring methods—also termed ‘retrofitting’—to meet regulatory frameworks (e.g., fish biomonitoring), and those investigating anthropogenic pressures by harnessing the full power of omics, for instance by sequencing the entire microbial diversity or by detecting resistance genes to antibiotics and metals in rivers. The carbon footprint and applicability of omics were also questioned, sparking animated debates among attendees. Finally, some presentations focused on methodological developments and encompassed sampling strategies and devices, issues related to reference libraries (completeness, curation), comparison of short reads versus long reads, and in situ detection and quantification of organisms (dPCR, models). The use of omics to study aquatic ecosystems is a fast‐evolving field. Meeting attendees agreed to maintain the generated momentum to promote omics as tools to improve the monitoring and protection of our environment
Characteristics of ocean mesoscale eddies in the Canadian Basin from a high resolution pan-Arctic model
No full textMesoscale eddies are ubiquitous in the Arctic Ocean and are expected to become more numerous and energetic as sea ice continues to decline. Yet, the spatio-temporal characteristics of these eddies are poorly documented. Here, we apply an eddy detection and tracking method to investigate mesoscale eddies in the Canadian Basin over the period 1995–2020 from the output of a high resolution (1/12°) regional model of the Arctic - North Atlantic. Over that period, about 6,250 eddies are detected per year and per depth level and are distributed about equally between cyclones and anticyclones. On average, these eddies last 10 days, travel 11 km and have a radius of 12.1 km. These statistics hide strong regional and temporal disparities within the eddy population studied. In the top 85 m, the seasonal, decadal and interannual variability in the number of eddies and in their mean characteristics follow that of the sea ice cover. In contrast, below the upper pycnocline, the eddy number and properties show a weakened seasonality. At all depths, eddy characteristics and generation rate show a strong asymmetry between the slope and the centre of the Canadian Basin. The upper 85 m show an increase in the number of eddies generated along the slope, while a net diminution of the number of eddies generated is visible within the pycnocline layer along the slope presumably due to the stabilizing effect of the slope. An increased number of eddies are generated in the vicinity of the cyclonic boundary current in the AW layer. The vast majority of eddies have no temperature signature with respect to their environment, although a significant portion of long-lived eddies, located along the Chukchi shelf break, have a non-negligible temperature anomaly and penetrate into the Beaufort Gyre, thus suggesting a mechanism for the penetration of heat into the gyre. The number of eddies generated within the upper 85 m increases by 34 % over the 25 year of simulation, with the largest increase occurring in the open ocean and marginal ice zone. The number of eddies between the upper and lower pycnoclines increases by 45 %, with a strong year-long increase in 2008, presumably in response to the Beaufort Gyre spin-up in 2007–2008. The number of eddies in the Atlantic Waters (AW) layer shows an overall increase of 41 % with little interannual variability. Finally, the analysis shows that the dominance of anticyclonic eddies within the Beaufort Gyre reported from measurements with Ice Tethered Profilers is partly due to a spatial sampling bias. This model-based eddy census can thus help interpret some of the discrepancies found between observational studies by providing a consistent spatio-temporal characterization of mesoscale eddies in the Canadian basin
New observations confirm the progressive acidification in the Mozambique Channel
No full textNew observations obtained in 2021 and 2022 are presented and used to investigate the trend of the carbonate system (including pH and aragonite saturation state, Ωar) in the southern sector of the Mozambique Channel. Using historical and new data in April–May we observed an acceleration of the acidification ranging from -0.012 TS.decade-1 in 1963–1995 to -0.027 (±0.003) TS.decade-1 in 1995–2022. Result from a neural network (FFNN) model for all seasons also suggests faster pH trend in recent decades, -0.011 TS.decade-1 over 1985–1995 and -0.018 TS.decade-1 over 1995–2022. In May 2022 we estimated Ωar of 3.49, about 0.3 lower than observed in May 1963 (Ωar = 3.86). The lowest Ωar value of 3.23 was evaluated from the FFNN model in September 2023 that corresponds to the hypothetical critical threshold value (3.25) for coral reefs. In 2025 a marine heat wave was observed in this region (sea surface temperature up to 30 °C) and data from a BGC-Argo float indicate that sea surface pH was low in January 2025 (pH = 7.95) whereas War was low in Mach 2025 (Ωar = 3.2). A projection of the CT concentrations based on observed anthropogenic CO2 in subsurface water and emissions scenario, suggests that a risky level for corals (Ωar < 3) could be reached as soon as year 2034
Rapport d'activités 2024 de l'Observatoire des biocénoses aquatiques de la Sélune
No full textDepuis 2012, un programme scientifique est mis en oeuvre sur le bassin de la Sélune. Il a pour objectif de fournir un retour d'expérience sur l'opération de restauration et de remise en continuité du fleuve côtier Sélune, en renseignant les changements induits par l'effacement des barrages hydroélectriques de Vezins et La Roche Oui Boit (LROB). L'effacement de ces deux barrages en 2020 et 2022, respectivement, a permis de reconnecter 60 km du cours principal de la Sélune, dont 19 km historiquement ennoyés, ainsi que l'ensemble de la partie amont de l'hydrosystème. Cela correspond à un linéaire total de 994 km (source: BD Topage), soit plus de 75% du linéaire total du bassin hydrographique si l'on considère l'ensemble des affluents. Jusqu'à présent, les travaux scientifiques visaient à comprendre le fonctionnement du cours d'eau avec les barrages (phase 1 : 2012-2019) et pendant leur déconstruction (phase 2 : 2019-2022). Depuis 2022 et la fin des travaux d'effacement des barrages (phase 3), les scientifiques suivent le processus de restauration du cours d'eau afin d'en comprendre les mécanismes. Parmi les actions menées, un suivi sur le long terme de divers paramètres avant, pendant et après le démantèlement des barrages était indispensable (McHenry and Pess 2008) afin d'appréhender le fonctionnement et l'évolution des milieux. Ainsi a été créé, en 2019, un observatoire des paramètres environnementaux de la Sélune : l'Observatoire Sélune. L'Observatoire Sélune rend compte de la dynamique de différents paramètres environnementaux en lien avec : les conditions abiotiques (coordonné par l'unité SAS de INRAE à Rennes) et les biocénoses aquatiques (coordonné par l'U3E de INRAE à Rennes). Le présent document rend compte des activités de suivi des biocénoses aquatiques pour l'année 2024, dans le cadre de l'observatoire Sélune et présente succinctement les résultats sur cette période. Aucune interprétation poussée des résultats n'est proposée, car l'observatoire a pour rôle d'assurer la collecte de paramètres environnementaux et de mettre à disposition les données acquises et traitées. La valorisation scientifique de ces données sera ainsi réalisée ultérieurement dans le cadre de programmes de recherche annexes. L'avancement et la réalisation des protocoles mis en oeuvre in situ et en laboratoire ainsi que les aspects calendaires, de fonctionnement et de valorisation sont renseignés pour l'ensemble des paramètres suivis
The Schistosoma Mansoni Male Tegument: An Ultrastructural Framework for Tubercles Morphogenesis
No full textThe tegument of Schistosoma mansoni adult males plays a central role in host–parasite interactions and is a major target for schistosomiasis treatment strategies. Despite its functional importance, the developmental biology of the male tegument—particularly the ultrastructural maturation of tubercles—remains poorly characterized. This study investigates the development of tegumental topography in adult male S. mansoni, with a focus on the ultrastructural formation of tegumental tubercles, which are key structures in drug development research. Beyond its surface functions, the tegument is critical for the immunological interface with the host and has recently emerged as a key site for somatic stem cell activity, making it a relevant target for studying regeneration, immune evasion, and therapeutic intervention in schistosomiasis
Scénarios pour la pêche et l’aquaculture en France en 2050
No full textLes mers et l’océan — auxquels la revue Futuribles a consacré toute une série d’articles entre 2020 et 2022 —, nous nourrissent, stockent le gaz carbonique, contribuent à la production d’électricité, sont un réservoir de biodiversité, mais sont aussi de plus en plus sous pression. Changement climatique, surpêche, pollutions… : les espèces aquatiques, animales comme végétales, sont menacées et avec elles, une partie des ressources contribuant à notre alimentation. Dans ce contexte, comment envisager l’avenir et faire en sorte que l’exploitation des ressources et services de la mer reste soutenable à long terme ? Afin d’éclairer les décideurs, citoyens et acteurs des secteurs en lien avec l’exploitation de la mer, une démarche prospective a été menée par l’Ifremer sur l’avenir de la pêche et l’aquaculture en France (projet « Foresea 2050 »). L’objectif était de proposer des scénarios décrivant divers futurs possibles pour ces filières, à l’horizon 2050, et d’esquisser les trajectoires les plus souhaitables. Mathieu Doray et Denis Lacroix présentent, dans cet article, la démarche prospective conduite entre décembre 2021 et juin 2023, qui a débouché sur cinq scénarios pour la pêche et l’aquaculture française en 2050, certains très négatifs (chaos, déclin) mais d’autres ouvrant des trajectoires plus positives (sobriété, zéro fossile, pari technologique). Ils précisent la méthodologie utilisée et les outils mis en place pour mesurer l’adaptabilité de ces scénarios à diverses ruptures possibles, positives comme négatives, et déterminer lesquels seraient les plus adaptables et propices à un développement durable. Cet exercice prospectif ouvre ainsi un certain nombre de pistes pour anticiper les changements à venir et permettre aux acteurs et instances économiques, scientifiques et politiques de cette filière, d’agir dès aujourd’hui pour s’orienter sur la trajectoire qui leur paraît préférable. S.D
Seasonal Mixed Layer Temperature in the Congolese Upwelling System
No full textThe Congolese upwelling system (CoUS), located along the West African coast north of the Congo River, is one of the most productive and least studied systems in the Gulf of Guinea. The minimum sea surface temperature in the CoUS occurs in austral winter, when the winds are weak and not particularly favorable to coastal upwelling. Here, for the first time, we use a high‐resolution regional ocean model to identify the key atmospheric and oceanic processes that control the seasonal evolution of the mixed layer temperature in a 1°‐wide coastal band from 6°S to 4°S. The model is in good agreement with observations on seasonal timescales, and in particular, it realistically reproduces the signature of the surface upwelling during the austral winter, the shallow mixed layer due to salinity stratification, and the signature of coastal wave propagation. The analysis of the mixed layer heat budget for the year 2016 reveals a competition between warming by air‐sea fluxes, dominated by the incoming shortwave radiation throughout the year, and cooling by vertical mixing at the base of the mixed layer, as other tendency terms remain weak. The seasonal cooling is induced by vertical mixing, where local wind‐driven dynamics play a secondary role compared to subsurface processes. A subsurface analysis shows that remotely forced coastal‐trapped waves raise the thermocline from April to August, which strengthens the vertical temperature gradient at the base of the mixed layer and leads to the mixing‐induced seasonal cooling in the Congolese upwelling system