Estimating plastic export from estuaries into the sea using an estuarine-mass-balance model
Estuaries act as an interface between rivers and the sea, and therefore play a key role in transporting plastic to the sea. However, plastic transport in estuaries is complex and estuary-to-sea export is still very uncertain. This study presents a macroplastic mass-balance model that can be applied to specific estuaries, and produces export estimates similar to previous studies. The daily plastic export from estuary to sea during the wet season was estimated to be 290 kg for the Rhine-Meuse Estuary (RME), and 19,431 kg for the Saigon Estuary, where the discharge into the sea is 3.5 times larger for the RME, compared to the Saigon Estuary. Due to limited river discharge measurements for the Saigon Estuary, a yearly simulation could only be performed for the RME, corresponding to an export of 13,300 kg. These estimates fall within the uncertainty range of previous studies. Deposition and remobilization from riverbanks resulted in the largest model fluxes, with magnitudes of 20 t/d for the RME and 430 t/d for the Saigon Estuary. At the same time, the model is most sensitive to the uncertainty in parameters related to deposition. Our results demonstrate that with the right measurements, making reliable estimates of estuary-to-sea export is possible. However, uncertainty in plastic transport processes, like deposition and remobilization, leads to poorly constrained parameters and increased overall model uncertainty. Automated sensors, targeted field experiments, and improved model structure can enhance export estimates and further improve understanding of plastic dynamics in estuaries.
(Marine Pollution Bulletin. vol. 230, n° 0025-326X, pp. 119793, 01/09/2026)
WUR, IGE, IRD, INSU - CNRS, CNRS, INRAE, Fédération OSUG, UGA, Grenoble INP, UGA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Evaluating migration hazard for recently remobilized managed coastal dunes
Sparsely vegetated or unvegetated coastal dunes are inherently dynamic, regardless of their size (Hesp et al., 2022). A salient characteristic of these dunes is their landward migration, driven by prevailing onshore winds, at rates that can exceed several meters per year. The rapid evolution of freely evolving coastal dunes inevitably raises concerns about the burial of infrastructure and more generally, the back dune areas. In a context where dune system remobilization is emerging as a nature-based management solution with multiple benefits (ecological reconnection, chronic marine erosion and sea-level rise effects mitigation), precise, spatially explicit quantitative assessments of dune migration hazards are essential. This is more critical given the trends of increasing urbanization and the concentration of socio-economic interests in coastal zones. Along the 230 km of the Aquitaine coast (southwest France), coastal dunes, which landscape is largely inherited from nearly two centuries of management, stabilization, and episodic mechanical re-profiling, have undergone spontaneous remobilization over the past decade (Nicolae Lerma et al., accepted). Across extensive sectors, dunes have transitioned from geometrically fixed, vegetated forms to aerodynamic, transgressive dunes (Figure 1a). This shift presents both opportunities and challenges for short- and long-term management strategies but also raises critical questions about accommodating rapid migration rates and evolving dune morphology. Current approaches to assessing burial hazards often overlook key parameters, such as interannual wind variability, climate change-induced trends in forcing, dune and back-dune morphology, and sediment budgets. Furthermore, methods relying on historical migration rates are inapplicable in regions where dunes were artificially stabilized during the 20th century through management interventions. Using annual airborne LiDAR data (Figure 1b.) and simulations with the morphodynamic model DUNA (Kombiadou et al., 2023, Figure 1c.), we analyze the factors influencing the migration speed of recently unvegetated dunes. We also investigate the impact of hybrid management strategies (designed to either accelerate or mitigate dune remobilization) at large spatial scales (hundreds of meters to tens of kilometers).
(13/07/2026)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ONF
Effect of the microparasite Perkinsus olseni on the bioturbation activity and engineering potential of the Manila clam Ruditapes philippinarum
Host behavioral modifications induced by parasites can have profound ecological consequences, especially when they affect ecosystem engineers such as bioturbators. While the influence of macroparasites on host behavior and, by extension, on ecosystem functioning is documented in the marine realm, the role of microparasites remains unexplored. The association between Perkinsus olseni, a widespread microeukaryotic parasite, and the Manila clam Ruditapes philippinarum, an abundant bioturbator in many coastal soft-bottom environments, is an interesting model for investigating this overlooked aspect. Infection by P. olseni has been shown to alter various physiological parameters in clams, such as immune response, metabolic activity, and reproductive performance. However, whether these internal disruptions translate into behavioral changes, such as modifications in sediment particle transports initiated by clams, remains an open question. In this study, we explore whether infection by P. olseni influences the bioturbation activity of the Manila clam, a process with significant implications for ecosystem processes, such as nutrient fluxes, in coastal environments. We did not report major changes in the engineering potential of the Manila clam when infected with non-lethal doses of Perkinsus olseni. However, we noticed a subtle increase in the magnitude of sediment transport activities, which may reflect behavioral adaptations. Given the ecological role of R. philippinarum as a driver of benthic processes, even little parasiteinduced behavioral shifts could cascade down to affect ecosystem processes such as sediment dynamics and benthic community structure. Exploring such interactions opens new perspectives on how microparasites may influence ecosystem functioning, not only through physiological disturbances but also via changes in host functional traits.
(Journal of Invertebrate Pathology. vol. 217, n° 0022-2011, pp. 108605, 01/07/2026)
ECOMAP, AD2M, SU, CNRS, SBR, SU, CNRS, EDYMAR, AD2M, SU, CNRS, SBR, SU, CNRS, AD2M, SU, CNRS, SBR, SU, CNRS, SBR, SU, CNRS, CNRS, STAMAR, INSU - CNRS, SU, CNRS, ISTerre, IRD, INSU - CNRS, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, UGA, FR2424, SBR, SU, CNRS, UB, Bordeaux INP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CENAREST
Continuous speleothem record from central Tunisia (the Mine cave) reveals climatic events for the last 27 ka
The Last Deglaciation, a key period punctuated by many climatic events, has been recorded in several natural archives but, it has been rarely recorded continuously on speleothems because of the presence of stops in their growth rate due to cold/dry climates. Here we present the results of a stalagmite (Min-stm2) from the Mine Cave (Oueslatia, Tunisia) that cover continuously the last 27 ka BP after a very slow growth between 120 ka to 35 ka. The time resolution, calculated with twenty-eight U/Th dating points and a 1 mm sampling space for stable isotopes, reaches 24 years during the Bølling-Allerød (BA) period, while it was the lowest (330 a/mm) during the Younger Dryas (YD). The growth rate (GR) curve reveals a sudden growth increase at 27.5 ± 0.08 ka BP, a key point in the stalagmite history, demonstrating that infiltration due to a humid and a relatively temperate climate started again at least in Tunisia. More vigorous northwesterly winds combined with the southern displacement of the ITCZ belt may explain this abrupt hydrological change. Despite of extreme cold climate that occurred N-Mediterranean area (i.e. Western Europe) during the Last Glacial Maximum (LGM) and the Oldest Dryas, the studied stalagmite kept a sustained GR showing a quite high humidity in the N-Tunisia area. The Last Deglaciation is here clearly marked by a large decrease in the calcite δ18O and δ13C between maximum values at 21.9 ka, denoting the coldest conditions, and minimum values at 8.5 ka coinciding with the warmest conditions. Even if the isotopic curves nicely mimic the ice and marine core records of the deglaciation, detailed events show some noticeable differences. For example, the stalagmite δ13C at the end of the BA is interrupted by a rapid and pronounced isotopic increase denoting colder conditions after 13.3 ± 0.1 ka BP which could be related to the IACP (Intra Allerød Cold Period). GR during the YD appears extremely slow. The Holocene onset, at about 11.7 ± 0.09 a BP, is marked by a gradual decrease in δ18O and δ13C until 8.3 ka associated with high GR suggesting increased precipitation. Despite the high time resolution during this period (better than 40 years), the 8.2 ka event is not recorded, marking a different sensitivity compared with more western and northern speleothem records. While the δ18O continuously increased after the Holocene optimum at 8.3 ka, a positive excursion occurred on the δ13C between 8.3 ka and 6.3 ka suggesting a reduction in the vegetation activity. This is likely due to increased seasonality with drier spring/summer conditions and humid autumn/winter and/or lower CO2 dissolution in the soil water during infiltration. The comparison with a former studied stalagmite from the same cave brings precious information about the local influences in recording detailed climatic variations.
(Quaternary Science Reviews. vol. 384, n° 0277-3791, pp. 109921, 01/07/2026)
LMRE, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, UTM, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IGEC, Xjtu, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, UNIROUEN, NU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Molecular detection reveals infection phenology of a host – Trematode system (Cerastoderma edule – Bucephalus minimus) in southwestern France
(Journal of Invertebrate Pathology. vol. 216, n° 0022-2011, pp. 108570, 01/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SBR, SU, CNRS
Adverse effects of sodium fluoride exposure on the development, thyroid morphology and disease resistance in rainbow trout (Oncorhynchus mykiss) embryos and larvae
Endocrine disruptors, ubiquitous in terrestrial and aquatic environments, have come under increased public and scientific scrutiny and are classified as substances of great concern for human health and the environment. The main objective of which is to determine the potential role of sodium fluoride (NaF) on rainbow trout health, with a particular interest in the thyroid hormone system, the immune system, and the development and behavior in early life stages. Rainbow trout ( Oncorhynchus mykiss ) embryos (265DD) were exposed for 15 days to NaF at 0, 0.5, 1, 5, 8 and 15 mg/L of F-. After the first 15 day-exposure, larvae were divided into three batches (1) exposed to NaF for further 8 days at the same concentrations, (2) infected with the Infectious Hematopoietic Necrosis virus, or (3) held in clean water. Fish were monitored daily to follow their development, morphology and behavior and sampled after 15 or 23 days of exposure, with and without viral infection, to evaluate effects on the THS (eye development, thyroid) and their capacity of resistance to IHNV. Results show impaired growth (decrease in size and an increase in the rate of abnormalities rate) and significative behavior impact at 15 mg/L of F- with a decrease of activity (speed, and light stress reaction). 5 mg/L of F- caused delayed hatching, a decrease in virus-related mortality, an increase of thyroid follicles number, and increased photoreceptor layer thickness. Further analyses will determine the immunotoxicity of this potential ED by analyzing gene activity and blood parameters in older fish.
(Aquatic Toxicology. vol. 295, n° 0166-445X, pp. 107815, 01/06/2026)
VIMEP, ANSES, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, VU, UB, ANSES
A multi-proxy sediment record of atmospheric contaminant deposition in the Paris Basin since the nineteenth century
Small ponds represent valuable but still underexploited archives for reconstructing long-term environmental contamination, particularly those disconnected to fluvial networks. In this study, a sediment core from the Saint-Denis pond (Paris Basin, France) was used to reconstruct the historical evolution of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and per- and polyfluoroalkyl substances (PFAS) over the last 150 years. The 137Cs record, characterized to the well-defined atmospheric fallout peak in 1963, was retained as the most robust age model, particularly for the second half of 20th century, when investigated contaminant dynamics were strongly influenced by human activities. The resulting chronology indicates continuous sediment accumulation from the late 19th century to 2021.Temporal trends in PAHs, PCBs, and PFAS closely match known historical production, use, and regulatory phases, providing independent validation of the 137Cs-based age model. Although indirect contaminant transfers via surrounding forest soils cannot be entirely excluded, the sediment record predominantly reflects atmospheric-driven contamination. This multi-proxy approach demonstrates the relevance of pond sediments for environmental monitoring and retrospective assessment of long-term contamination trends at the regional scale.
(Environmental Monitoring and Assessment. vol. 198, n° 0167-6369, pp. 625, 21/05/2026)
METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, EPHE, PSL, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, iSTeP, INSU - CNRS, SU, CNRS, GéHCO, UT, GEDI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Contrasting effects of seasonality and agricultural practices on periphytic biofilm metabolism and functions
Intensive agriculture exerts a strong pressure on biodiversity and the environment. Agroecological farming promoting ecological processes and ecosystem services appears as a promising alternative to conciliate commodity production and low environmental footprint. However, we lack proper quantitative assessment of the impact of various farming practices on adjacent natural ecosystems. Aquatic environments are particularly sensitive to land-use change, making it essential to evaluate how agricultural practices influence their ecological integrity. Periphytic biofilms, complex microbial communities colonizing submerged substrates, are widely recognized as relevant indicators of structural and functional biodiversity in aquatic ecosystems. Their rapid response to environmental variation makes them especially suitable for assessing the effects of agricultural practices. In this study, we investigated periphytic biofilms from two rivers, Barbanne and Engranne, along a gradient of agricultural practices (conventional, intermediate, organic). Biofilms were colonized on artificial substrates for four weeks during two seasons: spring (May–June 2025) and autumn (October–November 2025). Functional traits (algal composition, organic matter, photosynthetic and enzymatic activities), physicochemical parameters, and microbial activity through untargeted metabolomics were analyzed. During spring, functional traits revealed a clear spatial separation between the rivers. Engranne showed higher proportions of cyanobacteria and diatoms, with greater organic matter content, whereas Barbanne was dominated by green algae and exhibited higher copper tolerance. Multivariate analyses revealed a strong seasonal structuring of samples, distinguishing both rivers and seasons, but showing no clear effect of agricultural practices. Metabometabolomic profiles displayed the same trend, with samples grouped by season and not by agricultural practices. Overall, seasonality explained the observed variability better than the agricultural practices. This study underscores the need for multi‑season, multi-scale and long‑term monitoring to reliably evaluate the effects of agricultural practices on aquatic ecosystems.
(19/05/2026)
UR EABX, INRAE, UB, CNRS, INRAE, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR SAVE, UB, Bordeaux Sciences Agro, INRAE
Temporal Variability and Size-Fractionation of Trace Metals During a Diurnal Cycle in a Coastal System: The Case of Arcachon Bay
Coastal systems are vital to human societies, delivering numerous ecosystem services. However, human activities introduce contaminants, especially trace metals (TM) that contribute to their degradation. These environments are inherently dynamic and complex, characterized by rapidly occurring biogeochemical processes. As a consequence, highfrequency sampling is required to evaluate short-term TM dynamics. The hourly temporal variations in nine TM (V, Mn, Ni, Cu, Zn, Cd, Pb, Co and U) concentrations and sizepartitioning (<0.02, <0.2 µm, raw sample and in the suspended particulate matter) were investigated during a 27 h diurnal cycle within the Arcachon Bay (SW France). The results demonstrated that: (i) the TM were mainly represented in the potentially bioavailable fraction (<0.02 µm), except for Pb which remained predominantly associated with the particles, (ii) the temporal variability for U and V was only due to the mixing of water bodies contrarily to the 7 other TM, (iii) there was no clear influence of daytime conditions on TM concentration and/or size-partitioning, and (iv) a superimposition of multiple processes controlling TM speciation. Finally, the calculated risk quotients for species demonstrated an ecological risk for the marine biota for Co and Cu. These findings highlight the importance of high-frequency sampling combined with size-fractionation approaches to better resolve TM speciation dynamics, thereby helping to address the persistent knowledge gap in the distribution and biogeochemical cycling of TM between particulate, colloidal and truly dissolved phases in aquatic systems.
(Journal of Marine Science and Engineering, n° 2077-1312, 09/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Which benefits of fluvial annex sediment analysis for quantifying and tracing industrial pollution along the Saône River?
In the context of river ecological restoration in Europe and in order to achieve a “good” ecological and chemical status in watercourses, it is essential to quantify the volumes of contaminated sediment accumulated in fluvial annexes, which may be remobilized during floods or human interventions. These assessments not only allow the evaluation of ecotoxicological risks, but also help to assess the ecological functions associated with reconnection to the main channel. The Saône River (France), the main tributary of the Rhône River in terms of hydro-sedimentary contributions, has been little studied from this perspective, despite numerous developments (dykes) that have profoundly altered the lateral connectivity of its main channel. A more in-depth knowledge of the Saône River is therefore clearly needed to guide effective and safe ecological restoration actions.The volumes of sediments accumulated in three fluvial annexes distributed along the Saône River were estimated by combining ground-penetrating radar (GPR) transects with sediment cores sampling. These sediment archives were characterized (grain-size, organic matter content, trace metal content) to reconstruct the temporal trends of metal accumulation, based on ¹³⁷Cs and ²¹⁰Pb dating. Depending on the site, these sediment sequences provide six to eight decades of records, extending back to the 1940s for the longest. These data allow quantification of contaminants stocks (trace metals) and estimation of the annual load of contaminated suspended matters by the river in each site.The study sites exhibit contrasting morphologies and varying levels of lateral connectivity with the main channel. These differences influence the sediment storage volumes within the fluvial annexes, ranging from 8,000 m³ to 100,000 m³. These results reveal metal enrichment since the 1940s, with a clear and well-documented increase in Cd, Cu, Pb and Zn during the post‑World War II economic expansion (1950s), reaching maximum concentrations during the 1970s. Their concentrations subsequently declined in the 1990-2000s before stabilizing at lower plateau values.A specific feature concerns the contamination history of Ag, most likely driven by the photographic industry, which presented a three-phase pattern: (i) regular increase in the 1970s and 1980s, (ii) successive peaks between 1986 and 1994, and (iii) a marked decline in the late 1990s-2000s, with the decline of silver. This typical signal was observed at all studied sites along the river, despite hydrological connectivity differences. These sedimentary record complement monitoring data, especially for trace metals that were difficult to quantify in the past. This study highlights the major influence of historical contamination sources that released polluted sediments at the basin scale over several decades. This reconstruction also has national-scale implications and complements records obtained by other research works (such as on the Seine or Garonne rivers), highlighting the extent and persistence of pollution linked with photographic product manufacturing in Western Europe before 2000. Together, these results provide an integrated understanding of sediment dynamics and contamination, offering key insights for future river management and restoration strategies.
(04/05/2026)
LEHNA, UCBL, ENTPE, CNRS, ENTPE, ENTPE, LEHNA IAPHY, LEHNA, UCBL, ENTPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GéHCO, UT, [Anthropo-Sed], EVS, ENS de Lyon, Mines Saint-Étienne MSE, IMT, UL2, UJML, INSA Lyon, INSA, UJM, UJM EPE, ENTPE, ENSAL, CNRS, ALLHiS, UJM, UJM EPE