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Hydrogen diffusivity in iron-bearing olivine at asthenospheric mantle conditions
No full textInternational audienceThe effect of pressure on hydrogen diffusivity in San Carlos olivine (Fo90) single crystals was determined from hydrogenation experiments in a multi-anvil press at 6, 9 and 12 GPa, and at high temperature (900-1300°C), for various durations. Crystallographically oriented prisms of gem-quality San Carlos olivine were hydrogenated under controlled oxygen fugacity (Ni-NiO) and silica activity (10% Opx). Polarized Fourier-transform infrared spectroscopy was used to quantify the hydroxyl distribution in the samples parallel to the crystallographic axes. The diffusivity of hydrogen is consistent with a single diffusion mechanism, proton-vacancy coupled diffusion, which is dominated by the presence of trivalent ions (infrared band doublet at 3357-3329 cm−1). The inferred chemical diffusion coefficients are slower than in olivine hydrogenated at lower pressure (≤ 3 GPa) for the same diffusion mechanism and temperatures. Under the given experimental conditions, diffusion along the [001] axis is slightly faster than along [100] or [010]. Despite the pressure effect, hydrogen diffusion coefficients in the entire upper mantle remain fast enough to alter hydrogen concentrations at the grain scale, although too slow to enable km-scale re-equilibration of hydrogen-rich or hydrogen-poor anomalies. Melt migration is thus required to enable large-scale re-equilibration of H heterogeneities
Comparing Macroscopic and Quantitative Histological Methods to Determine Sexual Maturity in the Female European Plaice
No full textInternational audienceTo implement regulations in fisheries, like the minimum catch size for a species, data on the species' biological parameters must be collected and analyzed. Among these parameters, sexual maturity of the fish is evaluated. Multiple methods exist, and in this paper we used the macroscopic method (visual appreciation of the sexual organ to classify the fish into a maturity phase) and the stereological method (identifying and counting cells inside the fish's sexual organs to determine the maturity phase). The methods put forward try to minimize the subjectivity brought on by the human agent that will determine the maturity phase, through the implementation of guidelines and calibration exercises. Beyond lowering the human assessment bias, this article also shows that the macroscopic method, used to collect data that will later be exploited to set up fishery regulations, accurately determines the sexual maturity of female plaice only 40.4% of the time. This leads to estimations of size at first maturity of 28.6 cm for the macroscopic method compared to 20.6 cm when using stereology, differences in sizes that could have a major impact when setting up fishery regulations.</div
Déploiement et Maillage de stations instrumentées en IoT sur le territoire pour diverses études_AG AnaEE 2026 "ECOLOGGING"
No full textInternational audienceIn this poster, we present the deployments of the different types of instrumented stations developed within the framework of the "ECOLOGGING” project, carried out during the year 2024/2025, as well as the main developments, the results obtained, and the conclusions. The “ECOLOGGING” stations are deployed according to the nature of the studies conducted and the associated specific scientific needs.Dans ce poster, nous présentons les déploiements des différents types de stations instrumentées développées dans le cadre du projet "ECOLOGGING", réalisés au cours de l’année 2024/2025, ainsi que les principales évolutions, les résultats obtenus et les conclusions. Les stations ECOLOGGING sont déployées en fonction de la nature des études menées et des besoins scientifiques spécifiques associés
Disentangling Eastern Pacific Warming: El Niño 2023–2024 vs seasonal Panamá Bay influence
No full textInternational audienceUnderstanding the drivers of coastal ocean warming in the eastern Pacific is critical for distinguishing local variability from large‑scale climate phenomena such as El Niño. This study tests the hypothesis that anomalous warming in northern Ecuadorian coastal waters during January 2024 was primarily driven by the seasonal intrusion of Panamá Bay waters rather than the developing 2023–2024 El Niño event. Oceanographic and meteorological data were collected aboard the Pourquoi Pas? research vessel and compared against climatology (1940–2024), the 1997–1998 El Niño, and satellite observations. Winds were predominantly south-westerly, exceeding climatological averages while sea surface temperatures showed a pronounced south–north gradient. Salinity and mixed‑layer depths remained within seasonal ranges. The Intertropical Convergence Zone persisted north. Comparative analysis revealed weak or absent El Niño signals, with no discernible climatic impacts, wind, rain, thermocline and 20 C depths, T/S relationships, which were within seasonal values corroborated with biological and meteorological indicators. Instead, the seasonal incursion of Panamá Bay waters was the dominant warming driver. These findings refine understanding of eastern Pacific variability and provide the first deep profiles from this region, including serendipitous evidence of Antarctic Intermediate Water at ~1000 m, thereby enhancing observational coverage in a historically undersampled area
Le genre Chlorophytum Ker Gawl. (Asparagales, Asparagaceae) à Madagascar, avec la description de 12 nouvelles espèces, 4 nouvelles sous-espèces et 1 nouvelle variété
No full textInternational audienceThe genus Chlorophytum Ker Gawl. (Asparagaceae) is revised taxonomically for Madagascar. It is a palaeotropical genus of more than 200 species, all of which are geophytes that are distributed throughout Africa, the Arabian Peninsula (Oman), Southeast Asia, the Indian subcontinent, China and Australia. We recognise 39 endemic taxa for Madagascar (30 species, 4 subspecies, 3 varieties and 2 potential species not formally named due to incomplete material). Descriptions and geographical data are provided for all taxa, of which 17 are newly described in this revision: 12 species (C. albociliatum sp. nov., C. aspidistrifolium sp. nov., C. basivaginatum sp. nov., C. candelabrum sp. nov., C. darainense sp. nov., C. helvillae sp. nov., C. meridionale sp. nov., C. nigrogranulosum sp. nov., C. nusbaumeri sp. nov., C. ranirisonii sp. nov., C. ratovosonii sp. nov., C. tolyanum sp. nov.); 4 subspecies (C. sofiense subsp. gautieri subsp. nov., C. graniticum subsp. ambrense subsp. nov., C. meridionale subsp. ihosyense subsp. nov., C. meridionale subsp. tulearense subsp. nov.); and 1 variety (C. madagascariense var. boinense var. nov.). Chlorophytum gramineum (Baker) H.Perrier, is based on an illegitimate name (Anthericum gramineum Baker), and is replaced by the later legitimate name, C. madagascariense Baker, that we consider to be a taxonomic synonym. We retain the varieties described by Perrier de la Bâthie within this species, transferring them to C. madagascariense, and we give a new name – C. madagascariense var. pervillei nom. nov. Furthermore, we lectotypify eight species: C. decaryanum, C. decipiens, C. dianellifolium, C. geayanum, C. graniticum, C. namorokense H.Perrier, C. sofiense, C. subligulatum, and two varieties: C. dianellifolium var. transiens and C. madagascariense var. sciaphilum comb. nov.). An identification key and preliminary conservation status assessments following IUCN Red List criteria are provided for all species
Biochemical signatures of Holothuria tubulosa and Holothuria forskali (Echinodermata) in co-culture with sea bass in the Frioul Islands (France)
No full textInternational audienceConsiderable knowledge in the reproductive biology, habitat and life-history traits of European sea cucumbers was acquired in recent years with the objective to use them as extractive species in multi-trophic aquaculture systems. Yet, the trophic link between aquaculture wastes and sea cucumbers remains insufficiently evidenced. The aim of this study was to assess the potential of Holothuria tubulosa and H. forskali to utilise fish waste as a food source within a co-culture system. The two species were placed below sea bass cages in the northwest Mediterranean Sea. After one year of caging, fatty acids and stable isotopes indicated that sea cucumbers located near the fish cages were in good physiological condition. Higher levels of the fatty acid 18:2ω6, a biomarker of terrestrial plant oils, in sea cucumber tissues clearly indicate the transfer of fish feed to holothurians. In the case of H. forskali, this signature was also linked to an increase in bacterial biomarkers, indicating that sea cucumbers likely do not feed directly on fish wastes. Feeding habits differed between the two species, with H. tubulosa poorly modifying its diet when placed in captivity but probably requiring a significant access to sediment to maintain growth, while H. forskali probably collecting increased secondary production stimulated by the inputs of fresh organic matter directly on the cage walls. Finally, fatty acid profiles of both the body wall and muscular bands of the sea cucumbers revealed a similar imprinting of fish feed, indicating that each tissue can be analysed individually for trophic purposes
Anticipating potential environmental risks of offshore hydrogen production powered by offshore wind farm
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Phylogeny, systematics and evolution of mimicry patterns in Neotropical limenitidine butterflies
No full textDATA AVAILABILITY STATEMENT: The data that support the findings of this study are openly available in the Dryad repository at https://doi.org/10.5061/dryad.7h44j104b (Pàez et al, 2025). Newly generated sequences were deposited in GenBank at https://www.ncbi.nlm.nih.gov and are registered with the following accession numbers: PX243222–PX243274, PX244453–PX244551 (COI); PX114826–PX114854 (EF1a); PX172283–PX172334 (GAPDH); PX172335, PX254824–PX254850 (IDH); PX254786–PX254823 (RpS5); PX207538–PX207552 (ArgKin); PX172259–PX172282 (CAD); PX207522–PX207537 (CycY); PX172235–PX172258 (DDC); PX270910–PX270945 (Exp1); PX172202–PX172234 (Nex9); PX114965–PX115012 (PolII); PX114932–PX114964 (ProSup); PX114890–PX114931 (PSb); PX114855–PX114889 (RpS2); PX207556–PX207592 (UDPG6DH) (see Table S1 for details).International audienceThe Neotropical butterfly genus Adelpha Hübner exhibits remarkable species diversity and striking convergence in wing colour patterns potentially explained by mimicry, making it an exceptional model for exploring trait evolution and its relationship with speciation. To date, unresolved phylogenetic relationships hinder a comprehensive understanding of the evolutionary biology of the genus. Using a novel multi‐marker dataset combining one mitochondrial and 15 nuclear gene fragments, we generate the most comprehensive phylogeny of the genus Adelpha to revisit its systematics and investigate the evolution of mimicry colour patterns. Our dataset encompasses 83 of the 87 known extant species and six Limenitis species that were recently excluded from Adelpha (134 of c . 160 subspecies in total), collectively displaying 14 distinct mimicry patterns. We provide conclusive evidence that corroborates previous work on the polyphyly of Adelpha as historically conceived and describe the genus Adelphina Páez & Willmott n. gen . to stabilise the nomenclature. The comprehensive phylogeny provided in this study lays a solid foundation for future research into the processes driving diversification within these species interacting through mimicry. Ancestral character state reconstruction reveals the gradual evolution of mimicry patterns. The more common mimicry pattern IPHICLUS (forewing with orange subapical spot and white band) is inferred as ancestral, but repeated convergent evolution is also recovered. Evolutionary convergence is also observed for the second most abundant mimicry pattern, COCALA (orange‐white banded). Increased rates of mimicry pattern evolution are also found towards the equator. These results underscore the complexity of mimicry evolution in the Neotropical limenitidines, i.e., Adelpha and Adelphina n. gen. , emphasising the need to explore its interplay with other biotic and abiotic factors
Les défis olympiques de la luge : relations institutionnelles, représentativité internationale et standardisation des infrastructures (1964-2026)
No full textInternational audienceCe chapitre explore l’histoire olympique de la luge de course, entre 1964 et 2026. Discipline sportive au passé foisonnant quoique méconnu, la luge accède au milieu du XXe siècle aux honneurs olympiques pour ne plus quitter le programme de l’évènement quadriennal d’hiver. Restent des défis de taille pour asseoir sa place dans le microcosme olympique, parmi lesquels les relations institutionnelles entre la Fédération internationale de luge (FIL) et le CIO ; la question de la représentativité internationale de ce sport ; ou encore les évolutions techniques relatives à la confection des pistes dédiées (et bientôt « combinées » avec les pratiques du bobsleigh et du skeleton). En se reposant sur les archives du Centre d’études olympiques de Lausanne, l’analyse montre le chemin parcouru par le sport de luge jusqu’au cœur des Jeux d’hiver et du Mouvement olympique
Monitoring nitrogen pollution using isotopic composition of macrophytes in oligotrophic tropical coastal areas: A short review
No full textInternational audienceThis review explores the application of nitrogen stable isotopes measurements as a tool for monitoring nitrogen inputs in coastal zones, focusing on oligotrophic tropical ecosystems. Pulsed nutrient enrichment leads to the proliferation of macroalgae, compromising the health of coral reefs and seagrass beds. Through the analysis of 52 studies, we compile isotopic signatures measured in macroalgae and seagrass, while proposing reference thresholds to identify nitrogen pollution sources in tropical areas. By standardizing these isotopic compositions, our review aims to provide useful benchmarks for researchers and managers of coastal ecosystems. The main pollution sources identified include wastewater, groundwater, aquaculture, and fertilizers, each characterized by distinct δ 15 N ranges. Among these, wastewater and sewage show the highest isotopic values (>10 ‰), while inorganic fertilizers exhibit the lowest (down to -4.5 ‰). Macroalgae, particularly Dictyota and Rhodophyta species (e.g. Laurencia), were most frequently used as bioindicators due to their wide distribution and responsiveness to nutrient variation. Thalassia testudinum emerged as the most commonly used seagrass species across studies. However, seagrasses overall were less frequently employed than macroalgae, and typically displayed less sensitivity to nitrogen enrichment in their isotopic signatures. The review highlights practical aspects of isotopic monitoring, including macrophyte selection, caging techniques, sample preparation, and environmental variables affecting interpretation such as seasonality, depth, and hydrodynamic conditions. Caging, though underused in seagrass studies, proved essential in areas lacking native bioindicators. Finally, we provide recommendations for future studies to enhance consistency and standardization allowing temporal and intersites comparisons. This approach offers a cost-effective and sensitive tool for detecting nutrient inputs in vulnerable tropical ecosystems.</div