LA SÉCHERESSE FLUVIALE ET SES IMPACTS SOCIO-ENVIRONNEMENTAUX : CAS DE LA VALLÉE DE MANOMBO, SUD-OUEST DE MADAGASCAR
Le fleuve Manombo, avec la baisse de son débit ces dernières années, est révélateur du dérèglement climatique qui affecte le Sud-ouest de Madagascar. Or, la présence de ce cours d'eau demeure un des piliers majeurs sur lesquelles reposent les activités socio-économiques des populations riveraines. Notre recherche a pour objectif d'évaluer les impacts socio-environnementaux de cette diminution de la ressource en eau, à partir d'observations directes et d'enquêtes auprès des utilisateurs de la basse vallée du Manombo. Les premiers résultats montrent l'asséchement et l'ensablement de nombreuses terres agricoles situées en contexte fluvial (Baiboho) ou en parcelle irriguée (Tanety) ; les formations de mangroves sont également affectées. Ces changements se traduisent par : (i)une déstabilisation des sociétés en place en raison de pratiques agricoles devenues inadaptées mais également (ii) une dégradation des écosystèmes forestiers qui résulte de ponctions accrues de la part de populations devenues vulnérables en quête de nouvelles ressources.
(15/10/2026)
LAM, IEP Bordeaux, IRD, UBM, CNRS, UBM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Temperature variations in caves induced by atmospheric pressure variations-Part 1: Transfer functions and their interpretation
According to thermodynamics, atmospheric pressure variations (APV) cause temperature variations in air. However, such variations are difficult to observe, except in thermally stable environments such as underground cavities. We have studied the properties of these temperature variations in four natural caves in France, where continuous time-series have been collected since 1998: Esparros, Aven d'Orgnac, Pech Merle and Chauvet-Pont d'Arc Caves, the last two containing unique prehistoric wall paintings. The pressure to air temperature transfer function (TF), evaluated from 8 × 10-7 to 8 × 10-4 Hz, strongly depends on frequency; its modulus, at the barometric tide S2 (12 h), varies from 2 to 14 × 10-3 °C/hPa. While the TFs show pluriannual stability, seasonal variations are observed when sufficiently long data sets are available. Rock surface temperature is also affected by APV and we extract the air to rock surface temperature TF at Esparros, Chauvet and Pech Merle Caves. The observed TFs are accounted for by an improved analytical model including gas adiabatic compressibility, heat exchange with the rock, heat diffusion in the rock, phase changes of water at the rock surface and an advective term due to barometric pumping motion in the air volume. This model has three free parameters: the effective rock surface to air volume ratio, the time constant of heat exchanges and the effective adiabatic coefficient of cavity air. It is sufficient to account for the various situations observed in natural caves. Using this model, the observed TFs can be interpreted; they reflect the type of thermodynamics active at a given location, in particular the presence of barometric winds, but the actual values of parameters remain difficult to predict. Thus, temperature variations induced by APV emerge as a fundamental tool to characterize underground environments, relevant in some cases for cave heritage preservation, illustrating the coupled processes active in the Critical Zone.
(Geosystems and Geoenvironment. vol. 2, 15/10/2026)
IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS
Sea-level fluctuations control the distribution of highly liquefaction-prone layers on volcanic-carbonate slopes
Understanding and quantifying the hazards related to earthquake-induced submarine liquefaction and landslides are particularly significant offshore of tropical volcanic-carbonate islands, where carbonate production competes with volcanism to create highly contrasted lithological successions. To improve the detection of liquefaction-prone layers, we analyzed physical properties and mineralogy and performed 70 dynamic triaxial tests on 25 sediment cores offshore of the eastern side of Mayotte (Comoros archipelago in the western Indian Ocean) in an area that has experienced significant seismicity since 2018. We found that the main parameter controlling the liquefaction potential offshore of Mayotte is the presence of low-density layers with high calcite content accumulating along the slope during lowstands. This phasing with sea-level fluctuations implies a significant recurrent geohazard for tropical volcanic-carbonate islands worldwide. Furthermore, the relationship we found between the cyclic resistance of sediment and its density and magnetic susceptibility represents a time-effective approach for identifying the hazards related to earthquake-induced liquefaction.
(Geology. vol. 51, n° 0091-7613, pp. 402-407, 15/10/2026)
GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, 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, 15/10/2026)
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
Above and belowground functional space of herbaceous serpentinicolous species
Serpentine are described as stressful ecosystems being driven by multiple constraints including lack of nutrient, shallow soils and trace elements toxicity. Therefore, functional ecology theory predicts that serpentinicolous species should exhibit attributes similar to those of species found in other harsh environments, namely short size (plant stature functional axis), and slow soil-resource acquisition corresponding to conservative species (leaf economic spectrum axis) 1,2 . Our main objective was to verify if herbaceous serpentinicolous species found in western Europe were short and conservative as expected. Additionally, we investigated acquisitive roots traits related to mycorrhizal association and roots growth 3,4 . We sampled above and below ground traits of 46 species in 6 serpentinicolous herbaceous communities in the French Massif Central and the Apennines (Italy) in 2022. Aboveground traits were positioned in the global functional space provided by large database of aboveground plant traits. Principal component analysis on all measured traits provided additional insights regarding functional variation of studied species. If serpentinicolous species had small size as expected, they showed an important variation regarding the leaf economic spectrum and were not particularly conservative compared to the rest of herbaceous species sampled worldwide. This question the way corresponding species acquire nutrients in such harsh environments. Root trait analysis showed a large variety of strategies, species from the Apennines relying more on mycorrhizal association, and species from the Massif Central having faster root growth. This might be due to the biogeographical context and in particular the occurrence of a summer drought in the Mediterranean climate of the lower Apennines. Future work should investigate the correspondence of these functional variations with another tenet of functional adaptation of sperpentinicolous species: leaf metal accumulation or exclusion.
(15/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
RecruitNet: a global database of plant recruitment networks
Plant recruitment interactions (i.e., what recruits under what) shape the composition, diversity, and structure of plant communities. Despite the huge body of knowledge on the mechanisms underlying recruitment interactions among species, we still know little about the structure of the recruitment networks emerging in ecological communities. Modeling and analyzing the community-level structure of plant recruitment interactions as a complex network can provide relevant information on ecological and evolutionary processes acting both at the species and ecosystem levels. We report a data set containing 143 plant recruitment networks in 23 countries across five continents, including temperate and tropical ecosystems. Each network identifies the species under which another species recruits. All networks report the number of recruits (i.e., individuals) per species. The data set includes >850,000 recruiting individuals involved in 118,411 paired interactions among 3318 vascular plant species across the globe. The cover of canopy species and open ground is also provided. Three sampling protocols were used: (1) The Recruitment Network (RN) protocol (106 networks) focuses on interactions among established plants (“canopy species”) and plants in their early stages of recruitment (“recruit species”). A series of plots was delimited within a locality, and all the individuals recruiting and their canopy species were identified; (2) The paired Canopy-Open (pCO) protocol (26 networks) consists in locating a potential canopy plant and identifying recruiting individuals under the canopy and in a nearby open space of the same area; (3) The Georeferenced plot (GP) protocol (11 networks) consists in using information from georeferenced individual plants in large plots to infer canopy-recruit interactions. Some networks incorporate data for both herbs and woody species, whereas others focus exclusively on woody species. The location of each study site, geographical coordinates, country, locality, responsible author, sampling dates, sampling method, and life habits of both canopy and recruit species are provided. This database will allow researchers to test ecological, biogeographical, and evolutionary hypotheses related to plant recruitment interactions. There are no copyright restrictions on the data set; please cite this data paper when using these data in publications.
(Ecology. vol. 104, n° 0012-9658, pp. e3923, 15/10/2026)
CIDE, CSIC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFE, UPVM, EPHE, PSL, CNRS, IRD [Occitanie], IRD, INRAE, Institut Agro, UM
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, 15/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, 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, 15/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INERIS, ERT, IMT, HSM, IRD, INSU - CNRS, CNRS, UM, HSM, IRD, INSU - CNRS, CNRS, UM
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, 15/10/2026)
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
Continuum from microplastics to nanoplastics: effects of size and source on the estuarine bivalve Scrobicularia plana
Plastic has been largely detected in estuarine environments and represents major concern towards aquatic living organisms. The present study evaluates the impact of microplastics (MPs) and nanoplastics (NPs) under realistic exposure conditions. Scrobicularia plana individuals were exposed to low concentrations (0.008, 10, and 100 µg L−1) of environmental MPs and NPs as well as to standard PS NPs, as a comparison condition. The aim of this study was to understand the ecotoxicological effects of environmental plastic particles on S. plana gills and digestive glands but also to compare the effects of plastic polymers size in order to highlight if the size could induce different toxicity profiles within this model organism, at different levels of biological organization. Results showed a differential induction of detoxification enzymes (CAT, GST), immunity (AcP), DNA damage processes as well as a differential effect on behavior and condition index of animals depending upon the type of plastic, the size, the concentration tested, and the type of organ. This study underlines the necessity of testing (i) plastics collected from the environment as compared to standard ones and (ii) the effect of size using plastics coming from the same batch of macrosized plastics. This study concludes on the future need directions that plastic-based studies must take in order to be able to generate a large quantity of relevant data that could be used for future regulatory needs on the use of plastic.
(Environmental Science and Pollution Research. vol. 30, n° 0944-1344, pp. 45725–45739, 15/10/2026)
BIOSSE, UCO, GR, UR, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS