A new species of Diopatra (Annelida, Onuphidae) from Akanda National Park in Gabon (West Africa)
Several ecological surveys were recently conducted in the Akanda National Park in Gabon. The main objectives of this study were to assess the urban impact on the estuarine ecosystem of Libreville and to document the benthic biodiversity of this ecosystem. Among all the species collected, a new species of Diopatra was discovered in different habitats, including mangroves. This species is described and illustrated in detail, and information on 16S gene is provided. Diopatra ariasi sp. nov. is a medium-sized species and belongs to the D. neapolitana complex, having antennae with long ceratophores and ventral lobes. This species is also characterized by the presence of ceratophores with 9–12 rings on antennae, by sensory buds which are semicircular, by spiraled branchiae from chaetiger 4–5; by bidentate pseudocompound falcigers with moderately long hoods in first four chaetigers; by pectinate chaetae with 11–15 teeth from chaetiger 6–8 and by bidentate subacicular hooks from chaetiger 15–18.
(Marine Biodiversity. vol. 55, n° 1867-1616, pp. 94, 21/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR MARBEC, IRD, IFREMER, CNRS, UM
Influence of cockle bioturbation on microphytobenthic primary producers: habitat and density-dependent effects
While the global impact of the edible cockle Cerastoderma edule on microphytobenthos (MPB) dynamics has been extensively studied, some underlying processes remain unknown, such as their non-trophic interactions. For this purpose, a laboratory mesocosm experimental approach was used to quantify the bioturbation generated by C. edule adults and their influence on oxygen and nutrient fluxes, MPB biomass and photosynthetic performance at the sediment-water interface. The effects of sediment properties and cockle densities (0, 288, 720 and 1,297 ind. m−2) were also investigated. Our results showed that cockles exert a net negative density-dependent effect on MPB biomass, with intensity varying according to sediment type. This is mainly due to sediment reworking by cockles and their emergence at the sediment surface, mechanically disrupting MPB biofilms. Nonetheless, the physiological status and photosynthetic performances of the remaining MPB cells were not impacted. This could be explained by cockle bioirrigation which stimulates nutrient fluxes at the sediment surface and cell turnover. In the finest sediment, the stimulation of MPB growth by nutrient fluxes did not compensate algal biomass loss due to burial, leading to a net decrease in MPB biomass. In coarser sediment, no significant impact of cockles on the net total MPB biomass was observed. This indicates a balance between suboptimal sediment condition for MPB, biofilm destruction by cockles, and enhanced bioirrigation rates that increase nutrient availability for MPB biofilms at the sediment-water interface.
(Marine Biology. vol. 172, n° 0025-3162, pp. 70, 21/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MERSEA, UNICAEN, NU, CESAM
Le mystère de la maladie des pêcheurs (2020-2021) sénégalais levé [Note politique AWA]
Il aura fallu quatre années d'investigations, la mobilisation d'une quarantaine de scientifiques à travers une vingtaine d'équipes de recherche situées dans une quinzaine de laboratoires à travers le monde, pour venir àbout de l'énigme de la maladie mystérieuse qui a sévit au Sénégal en 2020 et 2021 chez les pêcheurs artisans. Cette maladie mystérieuse a touché plus d'un millier de pêcheurs sénégalais, suscitant l'inquiétude et l'attentioninternationale, est une dermatite aiguë. Les mêmes symptômes sont apparus sur des pêcheurs artisans en Guinée en 2023. Une étude menée par un consortium scientifique international (article publié en février 2025)dévoile l'origine de cette maladie : une toxine, la Portimine A, produite par la microalgue marine Vulcanodinium rugosum, jusqu'ici inconnu au Sénégal et dans sa sous-région CSRP. Cette toxine, qui perturbe les cellules de la peau humaine, déclenche une inflammation sévère. Cette étude met en lumière une problématique plus large : l'impact croissant des toxines environnementales sur la santé humaine, dans un contexte du changementglobal, notamment le changement climatique et l'accroissement des flux de transport maritime qui favorisent la prolifération et la redistribution de certains micro-organismes marins, comme les dinoflagellés toxiques.Le trafic maritime favorise la dissémination d'espèces marines d'un écosystème à un autre, notamment par les eaux de ballast. L'épidémie de dermatite associée à la Portimine A illustre les risques imprévisibles queles transformations subies par les écosystèmes marins peuvent entraîner. Elle souligne également l'urgence de surveiller, de manière coordonnée interdisciplinaire à une échelle sous-régionale, les espèces marinesproductrices de toxines, de comprendre leurs mécanismes d'action et d'adaptation, et de développer des solutions pour prévenir et traiter les menaces qui pèsent sur la santé humaine et les écosystèmes marins.
(pp. 16 p. multigr., 21/02/2026)
LEMAR, IRD, IFREMER, UBO EPE, CNRS, IRD, UCAD, LERBO, COAST, IFREMER, PSMS, URCA, PHYTOX, IFREMER, LBCM, UBS, UBO EPE, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPBS, CNRS, EPE UT, Comue de Toulouse
Non-Stationary Model Free Parameter In Equilibrium Shoreline Modelling
The state-of-the-art equilibrium shoreline model proposed by Davidson et al. (2013) is used to hindcast shoreline evolution. A similar approach to the work of Ibaceta et al. ( 2022) is adopted, where they introduced non-stationary model free parameters to improve long term shoreline change predictions. An Ensemble Kalman Filter (EnKF) is implemented to track the temporal variability in model free parameters and explore if their evolution can be linked to the environmental forcing. A correlation between the winter wave energy and the model free parameter φ (beach memory) is identified where high energetic winters are followed by an increase in the parameter suggesting such time variation in beach memory can be parametrized.
(21/02/2026)
UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, WRL, UNSW
En-échelon Rifting and Origin of the Volcanism in the Comoros
Two volcanic provinces have been recently discovered during the SISMAORE oceanographic cruise in the Comoros archipelago in the North Mozambique Channel between Madagascar and East Africa: N'Droundé, along the North-eastern insular slopes of Grande Comores Island and Mwezi, in the abyssal plain, north-east of Mayotte and Anjouan islands. By combining bathymetry and backscatter data, high-resolution seismic reflection and sub-bottom profiles, we have identified and mapped various tectonic (faults, forced folds) and volcanic structures (lava flows, edifices, sills, dykes) at several spatial scales on the seabed and in crosssection within the sedimentary cover. We have characterized the volcano-tectonic structures (geometry, segmentation, and kinematics) to better understand the link (geometry, chronology) between tectonic and volcanic processes. We show that volcanic and tectonic features are controlled by tectonic processes and viceversa. Ridges, volcanic cones and lava flows are set up along fissures and dikes during main rifting events to accommodate a N40°E regional extension within an E-W right lateral shear transfer zone. The volcano tectonic features are Plio-Pleistocene. This transfer zone lies between the offshore branch of the East African rift system and Malagasy grabens and may have formed when the East African rifts propagated offshore. We evidence a major rifting episode in the last Ma. The estimated volume and flux of extruded lavas show that the volcanism of the Comoros could be related to shallow tectonic processes.
(Geochemistry, Geophysics, Geosystems. vol. 26, pp. e2024GC011576, 21/02/2026)
IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, BRGM, LMV, IRD, INSU - CNRS, CNRS, UCA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, iSTeP, INSU - CNRS, SU, CNRS, CY
Digital PCR (dPCR) vs. Quantitative PCR (qPCR) approaches for quantification of two Perkinsus species within clam tissue samples
The parasite Perkinsus olseni (Perkinsea, Alveolata), the etiological agent of Perkinsosis, infects a wide range of bivalves and gastropods, including clams, particularly in Europe. This parasite coexists in sympatry with another Perkinsus species, P. chesapeaki, which, as opposed to P. olseni, has not been directly associated to mortality events. Accurate detection and quantification of Perkinsus infections, even at low infection intensities, are crucial for monitoring clam population health and assessing risks associated with emerging diseases. In this study, we compared molecular methodologies based on duplex real-time quantitative PCR (qPCR) and digital PCR (dPCR) in order to develop effective host resource management strategies. We first evaluated detection capabilities and the impact of potential inhibitors using both methodologies across varying DNA concentrations. Subsequently, we applied these methods to two contrasting French environments: Noirmoutier, characterized by low prevalence and infection intensity, and Arcachon Bay, which exhibits high prevalence and infection intensity. Our results demonstrate that dPCR should be prioritized for detecting and quantifying parasites at low infection intensities (101 -102 cp.µL-1), as it might minimize false-negative results compared to qPCR. Notably, dPCR provided new insights and revealed cryptic infections, demonstrating greater efficiency in detecting P. chesapeaki in lightly infected sites such as Noirmoutier. Conversely, infection intensity was underestimated with dPCR relative to qPCR for clams with moderate to high Perkinsus infection levels (103 cp.µL-1 or higher), proving the latter more suitable for medium to heavily infected areas like Arcachon Bay. These findings are important as they represent the first in situ monitoring of both Perkinsus species using culture-free methodologies. This work provides essential tools for resource management and conservation strategies to address emerging diseases.
(Journal of Invertebrate Pathology. vol. 213, n° 0022-2011, pp. 108417, 21/02/2026)
SBR, SU, CNRS, AD2M, CNRS, SBR, SU, CNRS, ASIM, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Rapport intermédiaire du projet Vigie-Lacs
L’objectif du projet est d’acquérir des connaissances scientifiques indispensables à la préservation des communautés de plantes aquatiques des lacs et étangs du littoral aquitain fortement menacées par les activités humaines et le changement climatique. Ce projet pluridisciplinaire fait appel à plusieurs domaines scientifiques complémentaires, telles que l’écologie des communautés, l’autécologie, la biogéochimie, les biostatistiques, la génétique ou encore l’hydrogéologie.
(pp. 24, 21/02/2026)
UR EABX, INRAE, ECLA, USMB [Université de Savoie] [Université de Chambéry], INRAE, OFB, BioGeCo, UB, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Differentiating estuarine dissolved organic matter composition by unsupervised and supervised machine learning
Differentiating the composition of Dissolved Organic Matter (DOM) in estuaries is a major environmental concern, as the DOM characteristics are closely linked to biogeochemical and ecological considerations (e.g. water properties and trophic cycling). However, tracing the spatiotemporal variations of estuarine DOM is challenging due to multiple sources and complex transformation processes. Here, we investigate the dynamics of estuarine DOM by analyzing the optical properties of DOM through UV-Visible absorbance and fluorescence spectroscopy, while also capturing the variability of DOM using machine learning algorithms and explainable artificial intelligence. To this aim, we collected sub-surface water samples (n = 249) from a human-impacted estuary with intense industrialization and urbanization in France (Seine Estuary) across distinct land use characteristics in contrasting hydrological conditions. We then applied unsupervised and supervised machine learning techniques to analyze the optical properties of DOM, which were determined by UV-Visible absorbance and Excitation-Emission Matrix (EEM) fluorescence spectroscopy combined with parallel factor analysis (PAR-AFAC). Our results show that unsupervised machine learning (K-means clustering) captures the spatial variabilities of DOM, identifying three distinct estuarine zones based on pronounced spatial variations of several DOM optical parameters. Supervised machine learning (Light Gradient Boosted Machine, LightGBM) further validates the rationality of the defined zonation. Subsequently, explainable artificial intelligence based on SHapley Additive exPlanations (SHAP) analysis shows that DOM in each zone has specific characteristics. Our model indicates that DOM in the Seine Estuary is primarily influenced by high molecular weight materials and autochthonous contributions in the upper estuary (Zone I). The dominant contribution to DOM in the mid-estuary (Zone II) comes from autochthonous and aromatic material as well as transformation and (photo)degradation products. Lower estuary (Zone III) is mainly characterized by aromatic DOM (subject to photodegradation), low molecular weight compounds, autochthonous DOM, as well as transformation and (photo)degradation products. Overall, this study presents a workflow for differentiating the composition of DOM, tracing the variability and dynamics of DOM along the land-to-sea continuum, and elucidating the involved processes. The approach developed in the Seine Estuary has significant implications for environmental management and can be adapted to other land-sea continuums.
(Water Research. vol. 284, n° 0043-1354, pp. 123900, 21/02/2026)
METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Semi-empirical forecast modelling of rip-current and shore-break wave hazards
Sandy beaches are highly attractive but also potentially dangerous environments for those entering the water as they can be exposed to physical hazards in the surf zone. The most severe and widespread natural bathing hazards on beaches are rip currents and shore-break waves, which form under different wave, tide, and morphological conditions. This paper introduces two new, simple semiempirical rip-current and shore-break wave hazard forecast models. These physics-informed models, which depend on a limited number of free parameters, can be used to compute the time evolution of the rip-current flow speed V and shore-break wave energy E sb . These models are applied to a high-energy mesotidal-macrotidal beach, La Lette Blanche, in southwest France, where intense rip-currents and shore-break wave hazards co-exist. Hourly lifeguardperceived hazards collected during patrolling hours (from 11:00 a.m. to 07:00 p.m. LT (UTC+2)) during July and August of 2022 are used to calibrate the two models. These data are also used to transform V and E sb into a five-level scale from 0 (no hazard) to 4 (hazard maximised). The model accurately predicts rip-current and shore-break wave hazard levels, including their modulation by tide elevation and incident wave conditions, opening new perspectives for forecasting multiple surf-zone hazards on sandy beaches. In addition, daily-mean hazard forecasts demonstrate even greater predictive skill, which is important for conveying straightforward messages to the general public and lifeguard managers. The approach presented here only requires a limited number of beach morphology metrics and allows for the prediction of surf-zone hazards on beaches where wave and tide forecasts are available.
(Natural Hazards and Earth System Sciences. vol. 25, n° 1561-8633, pp. 2379–2397, 21/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR ETTIS, INRAE, SMGBL, UR EABX, INRAE
Valve behavior of the oysters Crassostrea gigas and Ostrea edulis and physicochemical data measured during a one-year semi-controlled experiment testing the in situ impact of artificial light at night
Artificial light at night (ALAN) is a worldwide anthropogenic pressure altering the natural sun- and moonlight cycles, with putative impacts on organisms' biological rhythms, physiology, and fitness. Compared to terrestrial organisms, ALAN effects have been little studied in coastal ecosystems, despite their widespread exposure to ALAN. To help fill this gap, as part of the LUCIOLE project, we conducted a one-year in situ semi-controlled study to assess the ALAN impact on Crassostrea gigas and Ostrea edulis, two coastal and sessile oyster species likely exposed to ALAN. The experiment took place in the "île aux oiseaux" (44.7°, -1.18°) in Arcachon Bay (France) from December 2023 to November 2024. The experimental platform consisted of two oyster tables spaced 18 meters apart: one table for the control condition exposed to natural light and one table exposed to a continuous and realistic ALAN intensity (⁓10-6 µE/cm2/s; ⁓0.5 lx) using LED strips (white light). 16 individuals of each oyster's species were disposed on each table and were immersed underwater throughout the experiment. Their valve behavior was continuously measured during one year using the High-Frequency Non-Invasive (HFNI) valvometry. In addition to the oyster behavior, several physicochemical parameters were continuously measured underwater during the experiment: temperature, water depth, conductivity, salinity, turbidity, sound pressure magnitude, and light irradiance. This compilation of datasets gives an overview of all physicochemical parameters and behavioral data collected during this experiment.
(21/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS