Molecular detection reveals infection phenology of a host – Trematode system (Cerastoderma edule – Bucephalus minimus) in southwestern France
Accurate detection of parasites in their hosts is essential for pathogen control and ecosystem studies. The trematode Bucephalus minimus (Digenea: Bucephalidae) infects the edible cockle Cerastoderma edule, a commercially fished and ecologically important bivalve that serves as its first intermediate host, in which it can be difficult to detect. We investigated detection accuracy and infection phenology of this host-parasite system in Arcachon Bay, France. Cockles were collected monthly over one year to compare detection methods: stereomicroscopy of tissues versus molecular detection by quantitative PCR (qPCR) and digital PCR (dPCR). Visual detection reported 30% prevalence, qPCR 36%, and dPCR 50%, the most sensitive method. Seasonal cockle sampling and cohort analysis enabled tracking of the 2021 cohort over two years (Sep 2022 -Jun 2024) using both visual and molecular detection. With both approaches, first infection appeared when the cohort reached 14 mm shell length in fall 2022, most likely coinciding with sexual maturity. Molecular detection consistently revealed higher prevalence and greater temporal variation than visual detection, allowing for the first description of an infection phenology in this system. Prevalence sharply rose in spring 2023, was highest in summer, declined in fall, and increased again in spring 2024 to a lesser extent. These fluctuations appear linked to cockle size and maturity, as well as to the migration pattern of the definitive host (Dicentrarchus labrax), both influencing parasite transmission. Our results highlight the importance of using sensitive molecular methods to accurately assess parasite prevalence and understand transmission dynamics, essential for monitoring parasite and host populations.
(Journal of Invertebrate Pathology. vol. 216, n° 0022-2011, 23/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMS POREA, INSU - CNRS, CNRS, INRAE, ECOMAP, AD2M, SU, CNRS, SBR, SU, CNRS
Organic carbon composition and preservation in macrotidal coastal wetland sediment: insights from biomarkers and isotopic signatures
Coastal wetlands store high amounts of organic carbon (OC) in their sediments, but long-term preservation of this carbon depends on habitat type, sediment depth, and the molecular characteristics of organic matter (OM). This study explores the dynamics of OC deposition and preservation across vertical profiles (0–30 cm) in two adjacent coastal habitats—mudflat, and salt-marsh—within the macrotidal system of the Aiguillon Bay (France). A multi-tracer approach was applied, combining stable isotopes δ13C, C/N ratios, lignin phenols, and fatty acids. Sediment OC content ranged from 13.4 to 23.2 mgC g−1, with the highest concentrations found in the salt-marsh. δ13C and C/N signatures revealed dominant marine source in the mudflat, with a secondary contribution from microphytobenthos, and mixed marine–C₃ plant inputs in the salt-marsh. Fatty acids and lignin compositions supported this partitioning, with surface mudflat layers enriched in labile microbial and algal-derived compounds, whereas deeper salt-marsh sediments retained more resistant, C3 plant-derived signatures resembling those of terrestrial OM source. OM degradation rates were closely linked to source composition and depth. Degradation was concentrated within the top 5 cm of salt-marsh and the top 10 cm of mudflat. Below these depths, biomarker profiles changed minimally, delineating a transition to longer-term preservation. First-order degradation constants were three times higher in mudflat (0.53 yr−1) than in salt-marsh (0.17 yr−1), despite similarly high sedimentation rates (1.8 and 2.2 cm yr−1, respectively). This reflects differences in OM lability, with even minor contributions from microphytobenthos enhancing reactivity in mudflats. Salt-marshes, with their intermediate OM reactivity and high sedimentation rates, emerged as hotspots of carbon accumulation (366 gC m−2 yr −1), while mudflats also contributed substantially to coastal carbon sequestration (239 gC m−2 yr −1). These results highlight the value of depth-resolved, biomarker-based approaches to identify habitat-specific degradation dynamics; ultimately better understanding carbon accumulation in coastal ecosystems.
(Science of the Total Environment. vol. 1020, n° 0048-9697, pp. 181542, 23/05/2026)
LIENSs, INSU - CNRS, ULR, CNRS, iEES Paris, IRD, SU, UPEC UP12, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPG-ANGERS, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST
From Fixed to Transgressive Dunes, the Conditions and Timing of the Transition Along the Aquitaine Coast, France
Today most of the coastal dunes in temperate latitudes, especially in the northern hemisphere, are relatively stable. However, over the last decade, the Gironde coast, southwest France, has experienced substantial natural dune remobilization following a major marine erosion event. Annual, large-scale and high-resolution, airborne LiDAR data and Satellite imagery (Sentinel-2) are combined to address the coastal dune morphological changes and establish relations with forcing and controlling factors (vegetation cover, geomorphological descriptors). Between 2014 and 2023, about 10 out of 85 km of the Gironde dunes have switched from fixed to transgressive state. The analysis showed that in the vast majority of the cases the dominant process involved was dune front cannibalism. However, there is considerable spatial and temporal variability along the coast, depending on the vegetation cover evolution, the amount of sediment remobilized and the morphological characteristics of the dunes (steepness of the front slope, width)
(. vol. 41, pp. 10 - 15, 23/05/2026)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, ONF
Influence of Estuarine Turbidity Maximum Dynamics and River Discharge on Tide Propagation in Two Fluvial-Estuarine Systems
Tidal propagation in estuaries is shaped by the balance between morphological convergence and frictional effects, yet the influence of mud deposition associated with estuarine turbidity maxima remains unexplored. This study investigates the influence of Estuarine Turbidity Maxima (ETM) dynamics and river discharge on tidal propagation in the Loire and Gironde estuaries, combining frequency analysis of high-frequency observational data with an analytical model. Enhanced Harmonic Analysis reveals a tipping section-located downstream of the saline intrusion limit-in both hyperturbid systems, beyond which tidal properties (amplification, distortion, asymmetry) become highly sensitive to river discharge. Decomposing total friction into tidal, riverine, and interaction terms shows that the tipping point marks a regime shift where tide-river interaction dominates under low flow conditions, while the river term dominates during high discharge. Observations show that seasonal and interannual ETM-induced changes in bottom roughness can modulate tidal amplification by up to 35%, a mechanism confirmed by idealized modelling, while morphological changes have a more limited effect at these scales. Finally, scenario-based simulations suggest that sealevel rise and anthropogenic deepening may further enhance tidal amplification, 1 potentially promoting the upstream migration of salinity and turbidity maxima, with broader implications for estuarine functioning under future climate and human pressures.
(Estuaries and Coasts. vol. 49, n° 1559-2723, pp. 68, 23/05/2026)
RHITME, Cerema, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOMA, UB, CNRS
Non-stationary Model Free Parameter in Equilibrium Shoreline Modelling
The state-of-the-art equilibrium shoreline model proposed ShoerFor [1] is used to hindcast shoreline evolution. A similar approach to the work of Ibaceta et al. (2022) [2] 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.
(. vol. 42, pp. 646 - 651, 23/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, UNSW
Past trajectory of a Northwest Europe socio-ecosystem at the land-sea interface: Case study of the northern watersheds of the Bay of Brest over the last 150 years
The Bay of Brest (BB) is a macro-tidal estuarine environment that has been exposed to strong anthropogenic pressures over the past few decades, especially since the Second World War. This makes the BB an ideal site for studying coastal ecosystem transformations since the Industrial Revolution. We analysed five sediment cores collected in two key BB areas with varying exposure to marine hydrodynamic processes: i) the Elorn sector (3 cores) and ii) the Bay of Daoulas (2 cores) in the inner BB, close to the mouth of the Daoulas river. Our study used palynological (pollen and dinoflagellate cysts) and benthic foraminiferal assemblages, sedimentological data, and elemental geochemistry, at a very fine temporal resolution (2 to 16-year resolution). Working at a local spatial scale reveals robust correlations between the different driving forces and environmental changes over the last 150 years. Statistical analyses of these sedimentological and paleoecological time series reveal major breakpoints, specifically four key threshold periods: 1925–1938, 1960–1967, 1980–1987, and 2005, which are essential for understanding temporal changes in protist communities and the evolution of BB landscapes over this time period. Combining these findings with a reanalysis of regional precipitation patterns back to 1850, nutrient concentration data, and historical accounts of land-use practices, enables us to identify the main drivers of coastal ecosystem transformation. Our findings emphasize the strong influence of agricultural practices on trophic changes and the decline in the BB water quality, in agreement with coastal observatory series showing a notable increase in toxic algal blooms since the 1980s.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 690, n° 0031-0182, pp. 113703, 23/05/2026)
GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, BEEP, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEOARCHI, UBS, UBO EPE, IBSHS, UBO EPE, ENS Rennes, GR, UR, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, LMBA, UBS, UBO EPE, CNRS
Wave Input-Reduction for Shoreline Modelling of a High-Energy Environment with Complex Geological Settings
The long-term (decades) evolution of shoreline change along coastline (O(15)Km) with complex offshore wave transformation challenges both, state of the art process-based morphodynamics and reduce-complexity shoreline models. A major limitation is the computational time required to simulate the detailed spatiotemporal evolution of the wave field, particularly in regions where offshore wave refraction induces localized energy focusing. This study focuses on a 15-Km sandy coast on the North Medoc, southwestern France, characterized by high-energy, macro-tidal conditions, severe erosion, and complex offshore bathymetry. Effective coastal management strategies for the coming decades require the implementation of a reduced-complexity (RC) shoreline model. However, oversimplification of wave transformations in such a complex hydro-morphodynamic environment can result in flawed predictions of alongshore wavebreaking parameters and, consequently, shoreline change. Thus, a full wave propagation model is required, but computational time reduction techniques must be implemented to minimize computational cost. To address these challenges, this study introduces an easy-to-apply input reduction (IR) methodology that integrates offshore wave clustering to reduce computational costs when modeling long-term shoreline change within RC shoreline models.
(. vol. 42, pp. 652-658, 23/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
Colloid-facilitated release of PFAS from polluted-soil monoliths
Firefighting Aqueous Film Forming Foams contain per- and polyfluoroalkyl substances (PFAS). Because PFAS are persistent, firefighting training sites constitute a source of soil and groundwater contamination. Colloidal soil particles are known to facilitate the mobility of contaminants that have a strong affinity for soils. Indeed, colloid-facilitated transport of PFAS has been brought up repeatedly to discuss experimental observations regarding PFAS mobility. Still, it has only been observed experimentally for two PFAS molecules, using model experimental situations: repacked soil columns spiked with PFAS. We investigated for the first time the determinants and extent of colloid-facilitated transport of PFAS from AFFF-impacted undisturbed-soil monoliths during simulated rainfalls. These experiments showed that : (i) colloids contributed to the mobility—up to 70% of their concentration in leachates—of 12 PFAS having a perfluorinated carbon chain length nc ≥6, out of the 20 PFAS present in leachates; (ii) PFAS content in colloids was up to 25 times higher than in bulk soil, this enrichment stemmed from the adsorption on colloids of PFAS present in the soil solution; (iii) colloid-facilitated transport was exacerbated during transient flow regimes, which was probably related to the adsorption of PFAS and colloids to the moving air-water-interfaces. In addition, diffusion was the mechanism limiting the mobility of eight other PFAS with nc ≤7 and hydrodynamic conditions, linked to the soil structure, strongly affected the mobility of PFAS. The importance of colloidal particles as a carrier phase of PFAS calls for a renewed conceptual model of PFAS fate in soils.
(Journal of Hazardous Materials. vol. 511, n° 0304-3894, pp. 142279, 23/05/2026)
EMMAH, AU, INRAE, GERS-LEE, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRSTV, BRGM, UA, ULR, Cerema, CNRS, INSIS - CNRS, IMT Atlantique, IMT, Nantes Univ, Nantes Univ - ECN, Nantes Univ, Nantes Univ - ENSA Nantes, Nantes Univ, Institut Agro
Sustainability ranking of antifouling coatings for leisure boats – Balancing efficacy and environmental impact
Antifouling coatings are widely used on leisure boats to prevent biofouling, yet their environmental impacts vary significantly depending on formulation. This study systematically evaluated seven commercial antifouling products, including five copper-based coatings (with varying cuprous oxide content), one tralopyril-based coating and one biocide-free silicone foul-release coating. The evaluation included three complementary approaches: field-based efficacy testing, environmental risk assessment (ERA) modeling and ecotoxicological assays. Field trials were conducted over six months at three European coastal sites (Skagerrak, Kattegat and Atlantic) to assess the antifouling performance. Biocide release rates were quantified using X-ray Fluorescence and used to model environmental risks in accordance with EU guidelines. Acute toxicity of leachates was tested on four marine species (Aliivibrio fischeri, Phaeodactylum tricornutum, Artemia salina larvae and Oryzias melastigma larvae). The biocide-free silicone coating ranked highest in sustainability, combining strong antifouling efficacy with minimal acute toxicity. The copper-based coatings typically showed comparable efficacy at all sites despite differences in copper release but some only passed ERA thresholds in one of the sites (Atlantic). Lower copper content formulations generally exhibited reduced environmental impact. The tralopyril-based coating, despite being marketed as “environmentally safe”, demonstrated the highest toxicity and environmental risk. These findings highlight the need for environmental assessment of antifouling products to validate environmental safety claims and to promote lower impact formulations. While ERA modeling is suitable for biocidal products, ecotoxicological testing remains essential for biocide-free alternatives. Improved and standardized leaching protocols are needed to better reflect real-world conditions and support sustainable product development.
(Journal of Hazardous Materials. vol. 506, n° 0304-3894, pp. 141600, 23/05/2026)
OFB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GU, DTU, UMR MARBEC, IRD, IFREMER, CNRS, UM
Determinants of residential pesticide contamination in vineyard regions: a structural equation modeling approach
Background Previous studies have associated pesticide exposure among people living near fields with adverse health outcomes. However, the factors influencing residential contamination by agricultural pesticides remain unclear. Objective This study aims to assess the effect of the local environment, home characteristics, and occupant behaviors on residential contamination. Methods In 2021, wipe samples from outdoor and indoor surfaces were collected in 28 homes in Bordeaux vineyard region during peak pesticide spraying. Eight fungicides were analyzed by LC-MS/MS or GC-MS/MS. Environmental, residential, and occupant-related data were gathered through questionnaires and databases. Using multilevel structural equation modeling, we simultaneously examined the effects of multiple factors on pesticide contamination outdoors (Model 1, n = 227 samples) and indoors (Model 2, n = 543 samples), reporting standardized beta coefficients. Results Outdoor pesticide contamination was positively associated with local vineyard areas (beta = 0.79, p = <0.001) and the probability of a recent pesticide application (beta = 0.34, p = 0.09). In contrast, daily wind speed (beta = -0.54, p = 0.001), cumulative rainfall over the past month (beta = -0.32, p = 0.03), and cleaning (beta = -0.37, p < 0.001) were negatively associated with outdoor contamination. Indoor contamination was significantly associated with the annual local purchases of pesticides (beta = 0.79, p < 0.001) and pesticide track-in by occupants (beta = 0.16, p < 0.001). Conversely, households with active adults and children (beta = -0.49, p < 0.01), cleaning (beta = -0.40, p < 0.001), and surface contact frequency (beta = -0.30, p < 0.001) showed significant negative associations. Air exchange exhibited only a weak suggestive association (beta = 0.07, p = 0.09). Both models demonstrated good fit indices. Significance These results improve our understanding of residential pesticide contamination and could help inform the design of strategies to reduce exposure in rural populations.
(Journal of Exposure Science and Environmental Epidemiology, n° 1559-0631, 23/05/2026)
CHU Bordeaux, BPH, UB, INSERM, Irset, UA, UR, EHESP, INSERM, Biosit : Biologie - Santé - Innovation Technologique, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ECOSYS, INRAE