Physical processes matters! Recommendations for sampling microplastics in estuarine waters based on hydrodynamics
Monitoring the abundance and characteristics of microplastics in estuarine waters is crucial for understanding the fate of microplastics at the land-sea continuum, and for developing policies and legislation to mitigate associated risks. However, if protocols to monitor microplastic pollution in ocean waters or beach sediments are well established, they may not be adequate for estuarine environments, due to the complex 3D hydrodynamics. In this note, we review and discuss sampling methods and strategies in relation to the main environmental forcing, estuarine hydrodynamics, and their spatio-temporal scales of variability. We propose recommendations about when, where and how to sample microplastics to capture the most representative picture of microplastic pollution. This note opens discussions on the urgent need for standardized methods and protocols to routinely monitor microplastics in estuaries which should, at the same time, be easily adaptable to the different systems to ensure consistency and comparability of data across different studies.
(Marine Pollution Bulletin. vol. 191, n° 0025-326X, pp. 114932, 02/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sex-specific DNA methylation and transcription of zbtb38 and effects of gene–environment interactions on its natural antisense transcript in zebrafish
There is increasing evidence for the involvement of epigenetics in sex determination, maintenance and plasticity, from plants to humans. In our previous work we reported a transgenerational feminization of a zebrafish population for which the first generation was exposed to cadmium, a metal with endocrine disrupting effects. In this study, starting from the previously performed whole methylome analysis, we focused on the zbtb38 gene and hypothesized that it could be involved in sex differentiation and Cd-induced offspring feminization. We observed sex-specific patterns of both DNA methylation and RNA transcription levels of zbtb38. We also discovered that the non-coding exon 3 of zbtb38 encodes for a natural antisense transcript (NAT). The activity of this NAT was found to be influenced by both genetic and environmental factors. Furthermore, increasing transcription levels of this NAT in parental gametes was highly correlated with offspring sex ratios. Since zbtb38 itself encodes for a transcription factor that binds methylated DNA, our results support a non-negligible role of zbtb38 not only in orchestrating the sex-specific transcriptome (i.e. sex differentiation) but also, via its NAT, offspring sex ratios.
(Epigenetics. vol. 18, n° 1559-2294, pp. 2260963, 02/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMS POREA, INSU - CNRS, CNRS, INRAE, CBIB, UB, GeT-PlaGe, GET, GENOTOUL, UT3, ENVT, INSERM, CNRS, Toulouse INP, INRAE, INRAE, IBGC, UB, CNRS
Per- and polyfluoroalkyl substances (PFAS) in surface sediments: Occurrence, patterns, spatial distribution and contribution of unattributed precursors in French aquatic environments
While perfluoroalkyl sulfonic acids (PFSAs) and perfluoroalkyl carboxylic acids (PFCAs) are ubiquitous in aquatic environments, non-targeted methods have recently revealed the presence of numerous unidentified per- and polyfluoroalkyl substances (PFAS). Besides those methods, the total oxidizable precursor (TOP) assay has proved useful to estimate the contribution of unattributed perfluoroalkyl acids precursors (pre-PFAAs). In this study, an optimized extraction method was developed to examine the spatial distribution of 36 targeted PFAS in surface sediments collected at French nationwide scale (n = 43), including neutral, anionic and zwitterionic molecules. In addition, a TOP assay procedure was implemented to estimate the contribution of unattributed pre-PFAAs in these samples. Conversion yields of targeted pre-PFAAs were determined for the first time under realistic conditions and led to differences in oxidation profiles compared to the common spiked ultra-pure water method. PFAS were detected in 86 % of samples and ∑PFAStargeted was in the range < Limit of Detection – 23 ng g−1 dry weight (dw) (median: 1.3 ng g−1 dw), with ∑pre-PFAAstargeted representing on average 29 ± 26 % of ∑PFAS. Among pre-PFAAs, compounds of emerging interest such as the fluorotelomer sulfonamidoalkyl betaines 6:2 FTAB and 8:2 FTAB were respectively detected in 38 % and 24 % of samples, with levels similar to those of L-PFOS (<0.36–2.2, <0.50–6.8 and < 0.08–5.1 ng g−1 dw, respectively). A hierarchical cluster analysis coupled with a geographic information system-based approach revealed similarities between groups of sampling sites. For instance, elevated contribution of FTABs were associated with the proximity to airport activities where betaine-based aqueous film-forming foam (AFFFs) might have been used. In addition, unattributed pre-PFAAs were strongly correlated with ∑PFAStargeted and they accounted for 58 % of ∑PFAS (median value); they were generally found in larger quantity near industrial and urban areas where the highest ∑PFAStargeted were also observed.
(Science of the Total Environment. vol. 874, n° 0048-9697, pp. 162493, 02/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INERIS, ERT, IMT, HSM, IRD, INSU - CNRS, CNRS, UM, HSM, IRD, INSU - CNRS, CNRS, UM
Heart rate and behavioral responses in three phylogenetically distant aquatic model organisms exposed to environmental concentrations of carbaryl and fenitrothion.
Carbaryl and fenitrothion are two insecticides sharing a common mode of action, the inhibition of the acetylcholinesterase (AChE) activity. Their use is now regulated or banned in different countries, and the environmental levels of both compounds in aquatic ecosystems have decreased to the range of pg/L to ng/L. As these concentrations are below the non-observed-adverse-effect-concentrations (NOAEC) for AChE inhibition reported for both compounds in aquatic organisms, there is a general agreement that the current levels of these two chemicals are safe for aquatic organisms. In this study we have exposed zebrafish, Japanese medaka and Daphnia magna to concentrations of carbaryl and fenitrothion under their NOAECs for 24-h, and the effects on heart rate (HR), basal locomotor activity (BLA), visual motor response (VMR), startle response (SR) and its habituation have been evaluated. Both pesticides increased the HR in the three selected model organisms, although the intensity of this effect was chemical-, concentration- and organism-dependent. The exposure to both pesticides also led to a decrease in BLA and an increase in VMR in all three species, although this effect was only significant in zebrafish larvae. For SR and its habituation, the response profile was more species- and concentration-specific. The results presented in this manuscript demonstrate that concentrations of carbaryl and fenitrothion well below their respective NOAECs induce tachycardia and the impairment of ecologically relevant behaviors in phylogenetically distinct aquatic model organisms, both vertebrates and invertebrates, emphasizing the need to include this range of concentrations in the environmental risk assessment.
(Science of the Total Environment. vol. 865, n° 0048-9697, pp. 161268, 02/09/2026)
IDAEA, CSIC, CID-CSIC, CSIC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Author Correction: Freshwater influx to the Eastern Mediterranean Sea from the melting of the Fennoscandian ice sheet during the last deglaciation
(Scientific Reports. vol. 13, n° 2045-2322, 02/09/2026)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMD, INSU - CNRS, X, IP Paris, ENPC, SU, CNRS, ENS-PSL, PSL, GEOPS, INSU - CNRS, CNRS, GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], IRD, UniCA, AORI, UTokyo
Physiological effects of PFAS exposure in seabird chicks: A multi-species study of thyroid hormone triiodothyronine, body condition and telomere length in South Western France
There is growing evidence that poly and perfluoroalkyl substances (PFAS) exposure leads to the disruption of thyroid hormones including thyroxine (T4) and triiodothyronine (T3), and may affect telomeres, repetitive nucleotide sequences which protects chromosome ends. Many seabird species are long-lived top predators thus exhibit high contaminant levels, and PFAS-disrupting effects on physiology have been documented especially in relation to the endocrine system in adults. On the contrary, studies on the developmental period (i.e., chicks), during which exposure to environmental contaminants may have a greater impact on physiological traits, remain scarce to this date. We carried out a multi-species study with the aim to assess whether and to which extent chicks of four gull species (herring gull, great and lesser black-backed gull, yellow-legged gull) in South Western France are contaminated by PFAS, and to bring further evidence about their potential physiological consequences. Linear PFOS showed concentrations of concern as it was generally >10 times higher than the other PFAS, and exceeded a threshold toxicity level (calculated from previous studies in birds) in almost all sampled chicks. Nonetheless, in herring gull male chicks, total T3 levels were significantly and negatively associated with perfluorodecanoate (PFDA) and perfluorododecanoate (PFDoDA) and positively associated with perfluorotetradecanoate (PFTeDA) in female chicks. Total T3 levels were also positively associated with PFDoDA in great black backed gull male chicks and with perfluorotridecanoate (PFTrDA) in lesser black backed gull chicks. In lesser and great black-backed gulls, both females and males showed significant negative associations between several PFAS and their body condition, and a positive association between telomere length and L-PFOS in the yellow-legged gull. These results corroborate previous findings and need to be further explored as they suggest that PFAS may interfere with the physiological status of chicks during the developmental period, potentially inducing long-lasting consequences.
(Science of the Total Environment. vol. 901, n° 0048-9697, pp. 165920, 02/09/2026)
PhyMA, MNHN, CNRS, CEBC, ULR, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sampling terrigenous diffuse sources in watercourse: Influence of land use and hydrological conditions on dissolved organic matter characteristics
Diffuse and point sources of dissolved organic matter (DOM) in streams influence its composition, interactions and fate in the aquatic ecosystem. These inputs can be very numerous at the scale of a watershed, and their identification remains a challenge, especially for diffuse sources related to land use. The complexity of the transfer mechanisms and the reactivity of DOM throughout the soil-water column continuum raise questions about the sampling of diffuse sources in watercourses. To answer this issue, we compared the characteristics of soil-extracted DOM influenced by a particular land use (homogenous sub-catchment of forest and vineyard) and DOM collected from the watercourse adjacent to the soil samples. A 28-day incubation experiment of soil extracts was designed to remove the labile fraction of DOM. During the first 3 days, between 40 and 70 %of the DOC mass was lost for both types of soils. A set of optical indicators (UV–Visible, EEM fluorescence and HPSEC/UV-fluorescence) showed that the labile fraction was mostly composed by low (<1 kDa) and high (>10 kDa) protein-like molecules. At the end of the incubation, soil-extracted DOMwas mainly composed of medium molecules (1–10 kDa) associated to terrigenous humic-like compounds. Its optical and size molecular signature tended towards that in the adjacent watercourses and was specific to land use.However, the characteristics of DOMin watercourses was also influenced by the hydrological conditions, probably due to a transfer of top soil DOM during high water periods and both deep soil and autochthonous DOM during low water periods. These results were obtained by a set of indicators, including novel ones derived from HPSEC/UV-fluorescence. Finally, this study demonstrated that it is possible to sample the DOM representative of a land use directly in the river downstream of the homogeneous sub-basin by multiplying the samples during contrasting hydrological conditions.
(Science of the Total Environment. vol. 872, n° 0048-9697, pp. 162104, 02/09/2026)
RiverLy, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Marine diatoms record Late Holocene regime shifts in the Pikialasorsuaq ecosystem
Abstract The Pikialasorsuaq (North Water polynya) is an area of local and global cultural and ecological significance. However, over the last decades, the region has been subject to rapid warming, and in some recent years, the seasonal ice arch that has historically defined the polynya's northern boundary has failed to form. Both factors are deemed to alter the polynya's ecosystem functioning. To understand how climate‐induced changes to the Pikialasorsuaq impact the basis of the marine food web, we explored diatom community‐level responses to changing conditions, from a sediment core spanning the last 3800 years. Four metrics were used: total diatom concentrations, taxonomic composition, mean size, and diversity. Generalized additive model statistics highlight significant changes at ca. 2400, 2050, 1550, 1200, and 130 cal years BP, all coeval with known transitions between colder and warmer intervals of the Late Holocene, and regime shifts in the Pikialasorsuaq. Notably, a weaker/contracted polynya during the Roman Warm Period and Medieval Climate Anomaly caused the diatom community to reorganize via shifts in species composition, with the presence of larger taxa but lower diversity, and significantly reduced export production. This study underlines the high sensitivity of primary producers to changes in the polynya dynamics and illustrates that the strong pulse of early spring cryopelagic diatoms that makes the Pikialasorsuaq exceptionally productive may be jeopardized by rapid warming and associated Nares Strait ice arch destabilization. Future alterations to the phenology of primary producers may disproportionately impact higher trophic levels and keystone species in this region, with implications for Indigenous Peoples and global diversity.
(Global Change Biology. vol. 29, n° 1354-1013, pp. 6503-6516, 02/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
U–Pb age constraints on the Carboniferous-Permian transition in continental basins of eastern equatorial Pangaea (France): implications for the depositional history and correlations across the late Variscan Belt
Intramountain late Carboniferous–Permian basins of western Europe developed during the latest orogenic stages of the Variscan Mountain Belt in eastern Pangaea, at equatorial palaeolatitudes. Their stratigraphic framework is mainly based on continental subdivisions (e.g. Stephanian and Autunian continental stages), which can be contentious due to biostratigraphic biases, resulting in long-distance diachronous subdivisions. To provide precise inter-basinal and global correlations to the internationally recognized chronostratigraphic marine stages, this study reports new U–Pb geochronology from the Aumance and Decize–La Machine basins, located in the northern French Massif Central. Zircon grains extracted from three volcanic ash-fall layers give weighted mean 206 Pb/ 238 U ages of 299.11 ± 0.35 Ma; 298.73 ± 0.36 Ma and 298.59 ± 0.35 Ma (2σ total propagated uncertainty) by the chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) method, coinciding with the Carboniferous–Permian transition (Gzhelian and Asselian stages). These ages imply that the northern Massif Central basins developed synchronously in relatively short periods of time (<10 Myr), reflecting substantial sedimentation rates. Finally, the new chronology of infilling of these basins confirms that they were connected during the late Carboniferous and early Permian periods, improving the knowledge on the late-orogenic Variscan geodynamic setting in this area
(Journal of the Geological Society. vol. 180, pp. jgs2023-075, 02/09/2026)
GR, UR, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UniCa, MIT, BRGM, BGS, UB, CNRS
Blue mussels’ valve behavior exhibits daily and lunar rhythms during the high Arctic polar day
Marine species exhibit a multitude of biological rhythms, in accordance with their complex ecosystem governed by sun, earth and moon trajectories. Because of the inclination of the earth’s axis, the high Arctic ecosystem is characterized by several months of permanent illumination during the polar day. The persistence of biological rhythms in this photic context remains unclear. Yet, this information is crucial for the understanding of polar ecosystems functioning, as well as to predict the impact of future climate changes. Particularly, the impact of extreme photoperiods on recent invasive species remains largely unknown. Here, we investigate how environmental cycles shape the behavior of a re-emerging polar resident, the mussel Mytilus sp. during polar day (17 April to 26 August 2020; Svalbard, Ny-Ålesund, 78°56ʹ N, 11°56ʹ E). Our results show that in the high Arctic polar day, mussels’ behavior is shaped by both the photoperiod and the diel sun trajectories above the horizon. In addition, mussels also exhibit tidal, semi-lunar, and lunar rhythms of valve opening amplitude. We argue that these rhythms may have ecosystems functioning implications, and that the mussels’ ability to deal with drastic light regimes may explain their northward expansion and new resettlement in high Arctic.
(Marine Biology. vol. 170, n° 0025-3162, pp. 113, 02/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NIVA