New insights into subaqueous paleoseismology from the preserved imprints of paleo-earthquake markers on a normal fault scarp (Roseau Fault Lesser Antilles, France)
Assessment of seismic and tsunami hazards along coastlines requires knowledge of past earthquakes and their recurrence times along active submarine faults. To this end, subaqueous paleoseismological studies are performed and are based on sediment cores and seismic reflection images of faults. However, local site conditions sometimes preclude coring or seismic surveys and, even when possible, the resulting data may be limited. In addition to traditional geophysical and sedimentological data, seafloor geophysical data from submersibles can help elucidate the paleoseismic history of submarine faults. Here, we conducted a near-bottom geological survey using a Remotely Operated Vehicle (ROV) along the Roseau normal fault (Lesser Antilles, France) to study the fine morphology and paleoseismic history of an active submarine fault scarp. This fault hosted the Mw 6.3 2004 Les Saintes earthquake and shows a coseismic ribbon at its base. We used the submersible data to map and characterize several scarp morphologies including abrasion bands, notches, roughness changes, dark bands, and uplifted sediments along the fault scarp. We propose that these markers, which all formed at the seafloor, can ultimately be used to reconstruct the exhumation history of the fault scarp, because they are linked to base level changes (i.e. sedimentation and tectonic exhumation). At one site along the Roseau fault, the scarp’s detailed morphology can be explained by the occurrence of three earthquakes coupled to several episodes of rapid sedimentation. The penultimate earthquake may have generated a vertical offset of 3 m, where at the same location the 2004 event slipped by ~1.4 m. The penultimate earthquake was at least as energetic as the 2004 event, the Roseau fault being able to host a M7 event if broken entirely. Sediment rates from cores sampled near the fault show that the penultimate earthquake probably occurred within the past ~2.8 kyr. These observations highlight the potential of studying offshore faults with ROV optical imagery to better understand the seismic history of crustal faults.
(03/05/2026)
GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], IRD, UniCA, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, GFZ, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, iSTeP, INSU - CNRS, SU, CNRS, CY
Monitoring mineralogical and porosity transformations in modern Hebron ceramics caused by salt whitening agent using non-invasive methods
A field investigation conducted among potters in Hebron (Palestinian Territories) revealed the use of salt in clay pastes to produce white ceramics. An initial study (Teodorescu et al., 2022) sought to understand and explain this phenomenon. In addition to the visible whiteness, the potters also emphasised other qualities, such as porosity. This research aims to explore how the addition of salt influences the material’s properties to meet both the aesthetic and functional criteria valued by the potters. At the outset, raw materials and finished products were sampled directly from workshops in Hebron. A series of test briquettes were then produced in the laboratory following a protocol that allowed for precise control of both salt concentration and firing temperatures, based on the raw materials used by the Hebron potters. The goal was to assess the role of temperature and salt concentration in the development of the material’s pore structure. Firing temperatures were estimated from the reflectance spectral response obtained in the short-wave visible range (400–800 nm) and the infrared range (1000–2500 nm), using a hyperspectral camera (HSI). At the same time, the material’s porosity was examined through X-ray micro-tomography. The results indicated an increase in porosity with increasing temperature. More significantly, the addition of salt led to a redistribution of pores, favouring the formation of macropores. Furthermore, the results revealed that hyperspectral imaging is a highly promising non-destructive tool for estimating the firing temperature of ancient ceramics.
(Journal of Archaeological Science: Reports. vol. 71, n° 2352-409X, pp. 105660, 01/05/2026)
CEALEX, CNRS, UB, UBM, CNRS, PACEA, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, TEMPS, UP1, UPN, CNRS
High winter precipitation in Southern Europe during the Last Glacial Maximum as inferred from pollen sequences
(Quaternary Science Reviews. vol. 380, n° 0277-3791, pp. 109906, 01/05/2026)
GEOTOP, EPM, UdeM, UQAT, UQAR, UQAM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IACT, CSIC, UGR, HNHP, MNHN, UPVD, CNRS
Impact of combined atmospheric and marine heatwaves on the filtration activity of the invasive Asian date mussel, Arcuatula senhousia.
The Asian date mussel, Arcuatula senhousia, originated from East Asia, is a highly invasive species that severely affects ecosystem functioning and biodiversity in various ecosystems in America and Europe. In recent decades, heatwave events have increased in severity and frequency, causing additional stress for intertidal organisms living in one of the most thermally challenging habitats. Therefore, understanding the impact of stressful environmental conditions on species' behavioural responses is essential for predicting the effects of biological invasions in the context of climate change. This study aimed to evaluate the response of A. senhousia filtration activity under two levels of realistic combined marine and atmospheric short-term heatwaves (strong and extreme), performed during spring and summer conditions. Although numerous intertidal organisms have been shown to suffer greatly from heatwaves, the results indicate that A. senhousia is able to withstand short-term heatwaves. The results showed that, for all intensities and seasons, heatwaves had no significant effect on the clearance rate. Although there was no distinct general trend regarding the influence of heatwaves on the behaviour of valve opening in spring, strong heatwave conditions significantly increased the valve gaping activity (e.g., increasing valve opening and time of active filtration) during the summer experiment without significant difference on the clearance rate. This highlights the importance of considering the season when attempting to understand and predict the impacts of heatwaves. Therefore, this species exhibits a high filtration rate as well as tolerance to heatwaves. However, future investigations should investigate if this resistance have an impact on the species growth and survival at a longer term. In the context of climate change, this species may have advantage over native ones, and its abundances may significantly rise, leading to important ecological consequences in terms of communities structures and habitat modifications.
(Estuarine, Coastal and Shelf Science. vol. 332, n° 0272-7714, pp. 109767 (14p.), 01/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PatriNat, MNHN, IRD, CNRS, OFB - DSUED, OFB, LERAR, COAST, IFREMER
Testing a new approach to quantify intracellular trace metal contents in microphytoplankton using sequential selective extraction
Current methodologies used to quantify intracellular trace metal (TM) contents in microphytoplankton rely on the assumption that samples consist exclusively of phytoplankton cells, with no contribution from inorganic particles. Therefore, the present study aimed to propose a sequential selective extraction protocol for suspended particulate matter that preserve the cellular integrity of phytoplankton until the final Aqua Regia extraction. Seawater was collected in the Arcachon Bay and filtered through polycarbonate membranes (PC; Isopore™, 2 μm pore size). These membranes were put in contact with various extractants to isolate specific TM fractions. A subset of membranes was used for observation with scanning electron microscope (SEM) to assess the impact of the extractants on phytoplankton integrity. Among the tested solutions (i.e. ascorbate, 0.1 M NaOH, hydrogen peroxide, EDTA, 1 M HCl), only hydrogen peroxide was found to be destructive for the phytoplankton cells. Accordingly, a four-step sequential extraction was established: (1) ascorbate solution, (2) 0.1 M NaOH, (3) EDTA, (4) 1 M HCl, in order to selectively remove TM associated with inorganic phases or organic matter. Subsequently, PC membranes were digested by Aqua Regia to break down the phytoplankton cells and quantify the intracellular TM contents. The established protocol proves to be robust and effective to quantification the minimal TM content in diatoms and silicoflagellates cells. Results showed that Al, V, Mn, Fe, Cu, As, Pb, and Th were present in low proportion in the Aqua Regia solution (less than 20 % of the total content), suggesting limited internalization. In contrast, Cr (93 ± 3 %), Co (74 ± 23 %), and Ni (79 ± 17 %) fractions were dominantly present in the intracellular fraction suggesting they play major roles in TM biogeochemical cycles involving phytoplankton.
(Marine Environmental Research, n° 0141-1136, pp. 108113, 01/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
MAGEST: Rapport scientifique sur les données 2025
L'objectif de ce rapport scientifique est de présenter l'évolution saisonnière de la qualité physico-chimique des eaux des estuaires nord-aquitains (Charente, Seudre, Charente), qualifiée par la température, la salinité, la charge en matière en suspension et l'oxygénation, pour l'année 2025. Il s'appuie sur les données acquises par le réseau MAGEST (https://magest.oasu.u-bordeaux.fr/) et les données de débits de la Charente, de la Garonne, de la Dordogne et de l'Isle @HydroPortail, https://hydro.eaufrance.fr/). Cette année, le rapport inclut également les données du Département de la Charente-Maritime, issues de deux stations situées en l’aval et juste en amont du barrage de Saint-Savinien. L’année 2025 se classe au 4ème rang des années les plus chaudes depuis le début du XXème siècle derrière les années 2022, 2023 et 2020, devant 2024. Après une année 2024 très excédentaire, le cumul des précipitations de l’année 2025 est légèrement déficitaire (- 8 % en Nouvelle Aquitaine), avec de forts contrastes saisonniers (source : Météo France). Les faits marquants du réseau MAGEST en 2025 sont : - des températures moyennes journalières de l’eau comprises entre 4.8 et 28.9 °C, avec un début d’été 2025 parmi les plus chauds jamais enregistrés par MAGEST ; - une intrusion saline, définie par une salinité (moyenne journalière) supérieure à 0.5, d’intensité et de durée moyennes : 118 jours à Tonnay-Charente et 75 jours à Bordeaux ; - une arrivée mi-juin et un départ automnal (fin octobre - début novembre) du bouchon vaseux à l’aval de la Charente, de la Dordogne et de la Garonne ; - une baisse estivale de l’oxygénation de l’eau prononcée à Bordeaux et à Libourne, avec des périodes d’hypoxie à Tonnay-Charente. Les objectifs de la disposition oxygène du SAGE Estuaire de la Gironde n’ont pas été atteints à Bordeaux, avec 31 jours sous le seuil objectif de 5 mg/L (moyenne journalière), dont 21 jours consécutifs du 11 au 31 août. À Libourne, il y a eu 7 jours sous ce seuil. Tonnay-Charente a enregistré 68 jours sous le seuil objectif, dont 11 entre 1.6 et 3 mg/L. Enfin, un article récent sur une analyse des conditions estuariennes influençant les migrateurs dans des estuaires de la façade atlantique française est brièvement présenté.
(30/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Observational constraints project a ~50% AMOC weakening by the end of this century
Climate models show considerable discrepancies in their future projections around the Atlantic, mainly due to uncertainties in the fate of the Atlantic Meridional Overturning Circulation (AMOC). Climate models suggest a reduction in AMOC strength of 32 ± 37% by 2100 (90% probability, Shared Socioeconomic Pathways 2-4.5 scenario, Coupled Model Intercomparison Project Phase 6). To refine this estimate and reduce its uncertainty, we use four different observational constraint methods. The best one, which provides the lowest leave-one-out error, integrates a large set of observable variables using ridge-regularized linear regression—a method unusual in climate science. It gives an estimate of the AMOC slowdown of 51 ± 8% (90% probability), i.e., a weakening ∼ 60% stronger than suggested by the multimodel mean. This refinement mainly results from correcting a bias in South Atlantic surface salinity, consistent with recent studies emphasizing its role in the proximity to an AMOC tipping point. This more substantial AMOC weakening has key implications for future adaptation strategies.
(Science Advances. vol. 12, n° 2375-2548, 17/04/2026)
ASTRAL, IMB, UB, Bordeaux INP, CNRS, Inria, UB, Bordeaux INP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Assessing spatiotemporal changes in the benthic habitats of the West Gironde Mud Patch through the analyses of surface sediments, benthic macrofauna and sediment profile images
This work aims to refine the current assessment of spatiotemporal changes in the benthic habitats of the West Gironde Mud Patch. It follows a survey based on the analysis of surface sediment characteristics and benthic macrofauna composition at 5 stations located along a depth gradient, which was achieved between 2010 and 2018. The present work extends this observation period to 2021 and includes the indirect assessment of bioturbation through the analysis of sediment profile image characteristics. Temporal changes in surface sediment characteristics were essentially seasonal with strong increases in chloropigment concentrations in spring. Temporal changes in benthic macrofauna composition were mostly interannual with a major difference between 2010 and 2016-2021 currently attributed to the impact of a major physical disturbance during 2013-2014. In this study, extending the observation period shows that full recovery of benthic macrofauna composition had not yet been achieved by 2021. Sediment profile image characteristics (tube and organisms numbers, area of subsurface structures, oxic void depth and aRPD thickness) showed: (i) clear seasonal changes at the two deepest stations, mostly associated with a spring increase in tube numbers; and (ii) no significant difference between 2010 and 2016-2021, except at the deepest station. The discrepancy between benthic macrofauna composition and sediment profile image characteristics may result from differences in the recovery dynamics of benthic macrofauna composition and functionalities. Overall, results clearly call for a further extension of the WGMP observation period, which could consist in a yearly sampling at only two stations.
(Continental Shelf Research. vol. 298, n° 0278-4343, pp. 105637 (14p.), 01/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UA, CHROME, UNIMES, DYNECO, IFREMER
Deciphering copper and zinc leaching from antifouling paints with different operating modes: flux determination and toxicity evidence
Laboratory experiments were performed using 3 antifouling paints with different operating modes immersed in seawater for 7 days, to estimate copper and zinc fluxes and determine the scale of the related contamination. The toxicity of antifouling paints leachates was also assessed for natural bacterioplanktonic and phytoplanktonic communities. Given the increase in copper and zinc concentrations (4 to 1750-fold enrichment in dissolved Cu and to 7 to 200-fold enrichment in dissolved Zn), a systematic mortality upon phytoplankton was evidenced within 2 days of exposure to leachates produced from 1 hour to 2 days of immersion, whatever the paint. This went oppositely with the environmental risks calculated according to European guidelines, demonstrating an acceptable risk for the environment. Considering that 1 hour of leaching from a 7 cm² painted disk polluted 0.5L of seawater with Cu in our experimental conditions whatever the paint used, we estimated that a painted ship hull of 15 m² can pollute more than 10 m 3 of seawater within the same time. Leachates produced after only 20 minutes even yielded phytoplankton growth inhibition or mortality for insoluble and self-polishing paints, respectively, shortening the time needed for a freshly painted ship hull of 15 m² to pollute 10 m 3 . The bacterioplanktonic community appeared less sensitive than phytoplankton but demonstrated the same hierarchy: the highest toxicity was observed for the insoluble matrix and the lowest toxicity for the soluble one. This study therefore brings added value in terms of biocides flux determination, range of studied paints and concrete toxicity evaluation.
(Marine Pollution Bulletin. vol. 225, n° 0025-326X, pp. 119265, 01/04/2026)
MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Dominance of cellulosic and synthetic microfibers in upper layers of the Atlantic Ocean: evidence from the Vendée globe 2020 race
This study investigates the large-scale assessment of microplastic and anthropogenic microfiber pollution across the Atlantic Ocean, using continuous upper layer (0-5 m) sampling device aboard a sailing vessel during the Vendée Globe race 2020. Building on 53 samples and around 64 m 3 of filtered seawater, we applied three-stage size filtration 300 μm, 100 μm and 30 μm to capture small-size particles typically undersampled in large-scale oceanic surveys. Microplastic concentrations were inversely proportional to particle size, with the 30-100 μm fraction reaching mean values of 65.09 MP/m 3 -three times higher than the 100-300 μm range and over 60 times higher than for particles >300 μm. Smaller fractions exhibited higher polymeric and morphological diversity, dominated by polyethylene, polypropylene, and epoxy resins, while larger particles were mainly polyester and polyamide microfibers from textile sources. In addition, cellulosic fibers represented 87 % of the anthropogenic microfibers >100 μm, surpassing synthetic counterparts. These included cotton, viscose, and other regenerated or natural fibers, indicating diverse potential sources such as clothes, hygiene products, and cigarette butts. Geographically, high microplastic concentrations were observed in the North Atlantic (~106.2 MPs/m 3 on average) near European coastal regions, whereas lower levels in the South Atlantic subtropical region (~49.8 MPs/m 3 on average) suggest vertical redistribution and spatial heterogeneity mediated potentially by ocean dynamics. These results highlight the need to incorporate all anthropogenic particles across fine-scale size classes into marine pollution international assessments. Continuous, opportunistic sampling using leisure, commercial or race vessels is shown to be a valuable approach for capturing particle diversity in remote and open oceanic regions.
(Marine Pollution Bulletin. vol. 225, n° 0025-326X, pp. 119173, 01/04/2026)
RDT, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CBMN, UB, ENITAB, INC-CNRS, CNRS, LOPS, IRD, IFREMER, INSU - CNRS, UBO EPE, CNRS