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
DroneSCAT: A Drone-Borne and Low-Cost Microwave Scatterometer for Subsurface Imaging
Using low cost and commercial elements, we designed and realized a drone-borne microwave scatterometer in the 1-6 GHz range for subsurface imaging applications. The core of the instrument of a portable vector network analyzer associated to lightweight horn antennas produced using 3D printing. It is carried by DJI drones and accurate positioning is performed with the help of the free Centipede GNSS system. We validated our DroneSCAT instrument over a coastal parabolic sand dune, allowing the detection of buried paleosols down to 3 meters. We then tested it for archeological prospecting and detect a strong reflector buried 1 meter deep. The DroneSCAT instrument allows the detection of subsurface structures, with the benefit of a very agile system and without need for contact with the ground.
(Drone Systems and Applications. vol. 14, n° 2564-4939, 25/06/2026)
OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, LAB, UB, INSU - CNRS, CNRS, PACEA, UB, CNRS, UBM, CNRS, UB, UBM, CNRS, UB, UBM, CNRS, CNRS, UBM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Protracted ocean circulation slowdown drove exceptional ice-sheet melting during ice age termination IV
Glacial terminations stand out for their high rates of sea-level rise, particularly during meltwater pulses. Termination IV (T-IV; ~340,000 years before present) is a prominent example, with sea level rising at up to ~5 m per century. Due to sparse absolute age constraints on marine records, the causes for the high rates of sea-level rise at T-IV remain elusive. In this work, we provide a speleothem chronology from northern Italy, which we transpose to North Atlantic marine records. We infer that the high T-IV sea-level rise rate likely relates to a feedback whereby protracted meltwater release caused enhanced ocean heat storage, followed by heat release upon circulation recovery, driving additional ice-sheet collapse. This analysis highlights the critical role of oceanic feedbacks in driving exceptional rates of sea-level rise during terminations.
Middle to Late Pleistocene climate records feature sharp transitions between maximum glacial and interglacial climate conditions, referred to as glacial terminations 1-3 . Terminations were first identified in benthic foraminiferal stable oxygen isotope (δ 18 O b ) records from deepocean sediment cores 4,5 , where negative δ 18 O b shifts were ascribed to ice-volume reduction and associated release of 18 O-depleted meltwater to the ocean 6,7 . Independent sea-level reconstructions 8-11 have corroborated this picture and provided quantitative insights, showing strong agreement with individual and stacked benthic δ 18 O b time series that reflect both deep-ocean temperature and ice volume changes 12,13 . Detailed inspection of terminations reveals that ice-sheet retreat is not gradual; instead, there were times of accelerated collapse that led to meltwater pulses and remarkably high rates of sea-level rise 10,14 . Glacial terminations are also punctuated by millennial-scale climate perturbations, with abrupt shifts in oceanic and atmospheric temperatures and ocean circulation 15,16 that likely reflect bi-stability of the Atlantic
(Nature Communications. vol. 17, n° 2041-1723, pp. 5675, 16/06/2026)
NTU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IMPA, CCMAR, UAlg, IGEC, Xjtu, CEPAM, UNS, CNRS, UniCA, GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], IRD, UniCA, HNHP, MNHN, UPVD, CNRS
Reconstructing the Exhumation and Paleo‐Earthquake History of a Submarine Normal Fault From Preserved Markers at the Seafloor (Roseau Fault, Lesser Antilles, France)
Assessing seismic and tsunami hazards along coastlines requires understanding past earthquakes and their recurrence along active submarine faults. Subaqueous paleoseismology commonly relies on sediment cores and seismic reflection data, but these methods may be limited by local site conditions or data quality. To overcome these limitations, a new approach using submersible‐based optical imagery can provide valuable insights into the paleoseismic history of submarine faults. In this study, we conducted a near‐bottom geological survey using submersibles along the Roseau normal fault (Lesser Antilles, France). This fault can host a M7 event if broken entirely. In 2004, it generated the Mw6.3 Les Saintes earthquake that produced a prominent coseismic ribbon at its base. High‐resolution submersible observations of the fault free face allowed mapping and characterizing detailed fault scarp morphologies, including new deformation markers such as abrasion bands, notches, roughness variations, dark bands, and uplifted sediments. These geomorphic markers form on the seafloor and are interpreted as records of fault scarp exhumation linked to changes in base level driven by sedimentation and tectonic activity. At one site, the observed morphology can be explained by three distinct earthquakes combined with episodes of rapid sedimentation. The penultimate earthquake produced a minimum vertical offset of 3 m, exceeding the 1.4 m slip associated with the 2004 event, indicating that it was at least as energetic. Sedimentation rates from nearby cores indicate that this penultimate event occurred much more recently than 2.8 kyr. These results demonstrate the value of submersible‐based offshore fault studies for reconstructing seismic histories.
(Geochemistry, Geophysics, Geosystems. vol. 27, pp. e2026GC012905, 11/06/2026)
GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], IRD, UniCA, LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, GFZ, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, iSTeP, INSU - CNRS, SU, CNRS, CY
Modélisation morphodynamique de cordons dunaires en remobilisation sur le littoral de Nouvelle-Aquitaine
À la suite de l'hiver 2013-2014, les cordons dunaires de la côte aquitaine, fortement impactés par l'érosion marine, évoluent principalement sous l'effet des processus éoliens. Sur plusieurs kilomètres, des systèmes historiquement fixés par la végétation ont progressivement migré vers l'intérieur des terres sous forme de dunes aérodynamiques. Ces dynamiques offrent l'opportunité d'étudier les processus de remobilisation dunaire. Les modèles morphodynamiques éoliens constituent des outils prometteurs pour simuler ces processus, mais peu d'études ont évalué leur capacité à reproduire les observations in situ. À partir de données de vent, transport sédimentaire et topographie collectées lors de la campagne AEOLEX-1 sur le site de La Teste, cette étude évalue les performances du modèle DUNA. Les résultats montrent une bonne reproduction des processus physiques : le vent est correctement simulé (R² > 0,7 pour l'intensité, R² > 0,91 pour la direction) et, moyennant une calibration du paramètre separation angle, l'évolution morphologique présentent des erreurs centimétriques sur une année pour une dune de 25 m de hauteur. DUNA constitue ainsi un outil adapté pour l'étude de l'évolution des dunes peu végétalisées et offre des perspectives pour l'appui à la gestion des cordons dunaires remobilisés.
(Revue Paralia, n° 1760-8716, 09/06/2026)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS
L'hydrosystème dunaire littoral dans un contexte de changement global : prémices d'une étude hydrogéologique du continuum océan-dunes-lac en Nouvelle-Aquitaine
(09/06/2026)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
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, pp. 108570, 01/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMS POREA, INSU - CNRS, CNRS, INRAE, ECOMAP, AD2M, SU, CNRS, SBR, SU, 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
Physiologically based kinetics and toxicodynamic (PBK-TD) modelling in zebrafish embryos: A novel approach to assess endocrine disrupting chemicals acting on brain aromatase
Endocrine-disrupting chemicals (EDCs) can interfere with neurodevelopment through modulation of estrogen signaling pathways, including brain aromatase (cyp19a1b) expression. However, linking external exposure to internal dose and biological effects remains a key challenge for risk assessment. In this study, we developed a physiologically based kinetic-toxicodynamic (PBK-TD) model to describe the time-and concentration-dependent induction of brain aromatase in zebrafish embryos. Using EASZY assay protocol, transgenic tg(cyp19a1b:GFP) embryos were exposed to three model estrogenic compounds, 17α-ethinylestradiol (EE2), bisphenol A (BPA), and bisphenol F (BPF), from 0 to 96 h post-fertilization. GFP fluorescence and RT-qPCR measurements were used to characterize temporal dynamics of brain aromatase expression. A previously established PBK model was adapted to predict internal concentrations, particularly in the brain, and coupled to an indirect response TD model describing aromatase induction. The PBK model adequately predicted internal concentrations for all compounds (majority within 3-fold error). The PBK-TD model successfully captured the onset of inducibility (~44 hpf) and reproduced the full time-course of GFP responses. Internal dose-response analysis revealed substantial differences in potency between compounds, with EE2 showing markedly higher potency than bisphenols. Importantly, relative potency rankings differed when based on internal versus external concentrations, including an inversion between BPA and BPF. Overall, this work demonstrates that combining EASZY assay and PBK-TD modelling provides a more mechanistically relevant assessment of endocrine activity, improved interpretation of zebrafish embryo assays and is first step toward for quantitative in vitro-in vivo extrapolation and qAOP development.
(Computational Toxicology. vol. 38, n° 2468-1113, pp. 100423, 28/05/2026)
INERIS, SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
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ECOSYS, INRAE, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INRS, SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS