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
A wave-resolving two-dimensional vertical Lagrangian approach to model microplastic transport in nearshore waters based on TrackMPD 3.0
Potentially acting as a source or a sink for plastic pollution to the open ocean, nearshore waters remain a challenging context for predicting the transport and deposition of plastic debris. In this study, we present an advanced modeling approach based on the SWASH wave model and the TrackMPD (v3.0) particle transport model to investigate the transport dynamics of floating and sinking microplastics in wave-dominated environments. This approach introduces novel features such as coupling with advanced turbulence models, simulating resuspension and bedload processes, implementing advanced settling and rising velocity formulations, and enabling parallel computation. The wave laboratory experiments conducted by Forsberg et al. (2020) were simulated to validate the model's ability to reproduce the transport of diverse microplastics (varying in density, shape, and size) along a comprehensive beach profile, capturing the whole water column. Our results underscore the robustness of the proposed model, showing good agreement with experimental data. High-density microplastics moved onshore near the bed, accumulating in proximity to the wave-breaking zone, while the distribution of low-density particles varied along the coastal profile depending on the particle properties. The study also sheds light on the primary mechanisms driving microplastic transport, such as Stokes drift, wave asymmetry, and settling/rising velocities. Sensitivity analyses on calibration parameters further confirm the robustness of the model results and the influence of these factors on transport patterns. This research establishes the SWASH–TrackMPD approach as a valuable tool, opening avenues for future studies to contextualize laboratory findings within the complexities of real-world nearshore environments and further refine our comprehension of microplastic dynamics across different beaches and wave-climate conditions.
(Geoscientific Model Development. vol. 18, n° 1991-9603, pp. 319-336, 21/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SIAME, UPPA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS
Dynamics of low and high density microplastics in the world's largest choked coastal lagoon under contrasting meteoceanographic conditions
The contamination by plastic waste in aquatic environments has become a global issue, scientifically reported since 1970. The size and durability of microplastics (MPs, 1 μm > 5 mm) have made these debris widely distributed in aquatic environments. Despite various ongoing initiatives, there is a need to fill gaps in understanding how MPs are transported from their release sources to their final destinations. Therefore, understanding the distribution and dynamics of MPs in coastal areas, such as lagoons and estuaries, which are considered continental sources of MPs to the oceans, is essential to help fill these gaps and propose alternatives for managing what is the environmental problem of the century. In this context, this study aimed to assess the transport patterns of MPs in Patos Lagoon, the largest choked coastal lagoon in the world, considering contrasting meteoceanographic conditions in the system dynamics, such as wind and discharge. Using the hydrodynamic model TELEMAC-3D and the model for plastics particles TrackMPD, simulations were performed using a type of MP polymer (Polypropylene - PP). The simulations of MP transport considered advection, dispersion and the contribution of biofilm in increasing particle density (representing high-density microplastics). The results indicated a gradient of MPs retention from north to south, with higher concentrations of MPs occurring in the northern part of the system. The central region of the lagoon showed a greater tendency for MP export towards the southern region than retention. Meanwhile, the estuary region of Patos Lagoon exhibited a tendency for export of low-density MPs free of biofilm and retention of higher-density MPs, subject to the action of the Plastisphere. Additionally, based on the results obtained from density occurrence maps, it was possible to suggest potential accumulation areas of MPs throughout the lagoon system, reinforcing that the system can act as a sink in specific regions.
(Continental Shelf Research. vol. 285, n° 0278-4343, pp. 105396, 21/02/2026)
FURG, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
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
Underwater sound data, recorded during a 18-month in situ experiment in Helgoland, Germany
This dataset shows the hourly sound pressure magnitude data measured underwater throughout the 18 months of experiment (11th of May 2023 – 31st of August 2024) in Helgoland (Margate) for different frequencies (10 Hz, 20 Hz, 30 Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz, 80 Hz, 90 Hz, 100 Hz, 200 Hz, 300Hz, 400 Hz, 500 Hz, 600 Hz, and 700 Hz) recorded by the HFNI valvometer. The mean sound pressure magnitude is also presented. Missing data corresponds to the stop of recording of the valvometer.
(21/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, AWI, AWI
Record of trace organic contaminants in a river sediment core: A fingerprint of regulatory changes?
This study reconstructs the historical deposition of 76 trace organic contaminants (TrOCs), comprising pharmaceuticals, pesticides, and per-and polyfluoroalkyl substances (PFAS), in a dated sediment core taken from a secondary channel of the Seine River downstream of the Paris conurbation. Sediment chronology, established through $^{210}$Pb and $^{137}$Cs radionuclide depth activities, spans the period from 1943 to 2022, providing a long-term record of anthropogenic influence on fluvial contamination. The vertical profiles of pharmaceutical residues reveal temporal patterns closely aligned with their respective dates of market introduction, followed by increasing concentrations and subsequent declines. Maximum TrOC sedimentary concentrations were observed during the 1980s, coinciding with incomplete wastewater collection coverage. A sharp decrease in concentrations post-2000 reflects significant improvements in wastewater collection and treatment infrastructure. For pesticides, sedimentary trends also correlate with usage history and regulatory actions, with detectable declines frequently preceding official bans, suggesting the influence of progressive restrictions or shifts in agricultural practices. In contrast, PFAS profiles display more complex dynamics: legacy compounds such as perfluorooctanesulfonic acid and its precursors peaked in the early 2000s, after which their decline was offset by the increasing presence of alternative substances (e.g., fluorotelomersulfonic acids, betaines), indicative of industrial substitution. Overall, sediment composition had a secondary influence on TrOC profiles, with external factors such as regulatory decisions and technological developments in wastewater treatment playing predominant roles. These findings underscore the utility of collecting and analyzing sedimentary archives for assessing the long-term effectiveness of environmental policies and for identifying persistent and emerging contaminants in riverine systems.
(Journal of Environmental Management. vol. 389, n° 0301-4797, pp. 126276, 21/02/2026)
METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEDI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LEHNA, UCBL, ENTPE, CNRS
Reconstructing the Mid- to Late Holocene human-environments interactions in Cape Corsica (Corsica Island, Western Mediterranean) based on sedimentology, pollen analyses and geochemistry
This paper aims to reconstruct the interactions between human populations and their environment over the last 4500 years in Cape Corsica, a rocky peninsula situated on the northern edge of Corsica Island. During the Iron Age and Roman times, this region in the North Tyrrhenian Sea was at the crossroads of maritime trade routes, and was therefore recognized for its geostrategic position. However, little is known about its exact contribution in terms of natural resources exploitation and land use, nor regarding the general Late Holocene landscape evolution of the area. Three boreholes were drilled in three coastal lagoons situated on the eastern shore of Cape Corsica, at Biguglia, Meria and Macinaggio. To reconstruct the coastal landscape configuration together with vegetation history, land use and mineral extraction, laboratory work comprised granulometry, loss on ignition, pollen identification and elemental geochemistry. The chronostratigraphy is based on nine radiocarbon datings for all cores, and complementary 137Cs and 210Pb measurements were performed on the Meria core for recent chronology. For the northern edge of Cape Corsica, pollen results reveal that the highest human impacts on the vegetation composition were recorded during the Late Neolithic/Early Bronze Age, throughout Roman times, and in the Pisan-Genoese period, respectively. For all these periods, forest and maquis opening was observed to be coeval with cereal cultivation, thus revealing development of agriculture at the northern extremity of Cape Corsica. Conversely, the Middle to Final Bronze Age and pre-Christian era were characterized by a major recovery of the maquis and scarce evidence of land use. At Biguglia lagoon in the southern part of the peninsula, the vegetation composition for the last 1100 years reveals forest opening with moderate development of agriculture and, in the 10th Cent. CE., the connection between San Damiano Island and La Marana coastal barrier. In Cape Corsica, local contamination by mineral extraction (antimony in the form of stibine) is attested in the Meria valley during the known period of exploitation and also prior to this activity, possibly dating from the Genoese or the Corsican independence periods.
(Journal of Archaeological Science: Reports. vol. 62, n° 2352-409X, pp. 104985, 21/02/2026)
CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, IPHES-CERCA, URV, ULiège, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
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