HAL Collection UNC (Univ. de la Nouvelle Calédonie)
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Cartographie des coraux par imagerie satellite à très haute résolution. Application aux données Sentinel-2, SPOT6/7, Pléiades et Pléiades Neo sur les récifs de La Réunion
No full textInternational audiencePar leur situation géographique le long des côtes, les récifs coralliens forment une barrière naturelle vivante atténuant l’énergie des vagues entrantes, protégeant les écosystèmes côtiers et les populations humaines des risques de submersion, d'inondation et d’érosion. Ces récifs font face à des pressions et perturbations croissantes, conduisant à des épisodes de mortalités des coraux qui les constituent et à une dégradation de leur état à l’échelle mondiale. Le pourcentage de couverture corallienne vivante est l'indicateur le plus communément utilisé pour évaluer l'état de santé des récifs coralliens. Les données de télédétection, notamment aériennes hyperspectrales ont depuis longtemps été mobilisées à La Réunion et ont montré leur efficacité pour ces suivis. Il s’agit de données coûteuses donc peu exploitables comme outils de gestion. Cet article montre l’apport de la donnée multispectrale satellite pour établir le suivi des récifs, notamment avec l’essor de la Très Haute Résolution Spatiale. Nous testons ici la capacité de différents indices spectraux calculés sur quatre types d’images satellites multispectrales (Sentinel-2, SPOT6/7, Pléiades et Pléiades Neo) à détecter les couvertures coralliennes vivantes des récifs coralliens. Nous utilisons La Réunion comme cas d’étude. Grâce à des données de références historiques et in-situ nous mettons en évidence que :(1) Les images satellites peuvent détecter les coraux vivant grâce l’indice de brillance Bleu Vert BIBG (R2 > 0,60 sur données historiques)(2) La nouvelle image satellite Pléiades Neo à très haute résolution, comprenant une bande Deep Blue, permet une meilleure détection avec l’indice spectral de brillance Deep Blue Bleu BIDBB, (R2 = 0,63 sur données in-situ). La méthode développée appliquée au couple indice-image a permis de générer une carte actualisée des couvertures coralliennes à haute résolution de l’ensemble de la plateforme récifale de l’Hermitage à La Réunion
Developing EO-based framework for estimating biodiversity variables of coral reef and seagrass ecosystems at Large Scale
No full textInternational audienceBiodiversity is a vital component of natural capital that significantly influences ecosystem functions and provides essential services and benefits, ranging from food security to cultural heritage. However, species are currently disappearing at a rate 100 to 1,000 times higher than the natural extinction rate. Coastal ecosystems are particularly concerning: they are among the most vulnerable due to their exposure to cumulative anthropogenic pressures while biodiversity knowledge is lacking. Supported by the French National Space Agency (CNES) and endorsed by the Space Climate Observatory (SCO), the BioEOS project aims to develop observation tools to characterize the spatiotemporal dynamics of coastal biodiversity. This initiative will map changes and produce operational indicators to assist in conservation and restoration efforts in the Marine Protected Area (MPA). The project primarily takes advantage of image time series from multispectral (Pleiades, Sentinel-2, Venus) and hyperspectral (EnMAP, PRISMA) satellite systems. A set of selected biodiversity proxy metrics are extracted using high SRL (Scientific Readiness Level) algorithms that have been widely used by the benthic scientific community. These algorithms encompass the inversion of radiative transfer models, machine learning-based scene segmentation, spectral unmixing, pansharpening, and the calculation of spectral indices. This approach enables to generate valuable information on bathymetry, bottom/habitat type abundances and distributions, as well as water column properties estimations. Coral reef and seagrasses of Southwestern Indian Ocean region (La Réunion, Mayotte, Glorieuses and Bassas da India) are the first targeted ecosystems for this experimentation. We present the main advancements of a demonstrator providing key essential variables contributing to various end uses through four distinct use cases. Additionally, we will discuss the strengths and limitations of the satellite systems employed, in light of the initial objectives set forth
Pyromechanics: A solid mechanics approach to deformation during pyrolysis
No full textInternational audienceDuring pyrolysis, organic materials undergo morphological changes that are important to predict, particularly in the field of thermochemical conversion. This work proposes an approach to model deformations during pyrolysis combining elastic, thermal expansion, and pyrolysis contributions. A three-dimensional anisotropic pyromechanics model is derived for porous media by volume averaging. It includes pyrolysis kinetics, mass, momentum and energy conservation for both solid and gas phases. A key advantage of the pyromechanics model lies in its physical framework, which effectively captures the effect of internal stresses on the overall deformation. Implemented as open-source within the Porous material Analysis Toolbox based on the OpenFOAM framework (PATO) using an incremental approach, the model is specifically applied to wood in this study. Two experimental validations are conducted using pyrolyzing cylindrical wood particles to verify the model’s predictions concerning temperature profile evolution and shrinkage effects. Importantly, the model’s capability to estimate stress distribution holds promise for further investigations into crack distribution and propagation
An updated synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2023: the SNAPO-CO<sub>2</sub>-v2 dataset
No full textInternational audienceAbstract. Total alkalinity (AT) and dissolved inorganic carbon (CT) in the oceans are important properties to understand the ocean carbon cycle and its link with global change (ocean carbon sinks and sources, ocean acidification) and ultimately to find carbon-based solutions or mitigation procedures (marine carbon removal). We present an extended database (SNAPO-CO2; Metzl et al., 2024c) with 24 700 new additional data for the period 2002 to 2023. The full database now includes more than 67 000 AT and CT observations along with basic ancillary data (time and space location, depth, temperature, and salinity) in various oceanic regions obtained since 1993 mainly in the framework of French research projects. This includes both surface and water columns data acquired in open oceans, coastal zones, rivers, the Mediterranean Sea, and either from time series stations or punctual cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with certified reference material, with an overall accuracy of ±4 µmol kg−1 for both AT and CT. The same technique was used on board for underway measurements during cruises conducted in the southern Indian and Southern oceans. The AT and CT data from these cruises are also added to this synthesis. The data are provided in one dataset for the global ocean (https://doi.org/10.17882/102337, Metzl et al., 2024c) that offers a direct use for regional or global purposes, e.g., AT–salinity relationships, long-term CT estimates, constraint and validation of diagnostics CT and AT reconstructed fields, ocean carbon and coupled climate–carbon models simulations, and data derived from Biogeochemical Argo (BGC-Argo) floats. These data can also be used to calculate pH, fugacity of CO2 (fCO2), and other carbon system properties to derive ocean acidification rates or air–sea CO2 fluxes
"Les déesses irlandaises". Interview de Noémie BECK pour la Chaine YouTube Imaginaire celtique créée par Frédéric Armao, Noémie Beck et Gaël Hily. 15 juin 2025. sous-titrée en anglais. https://www.youtube.com/watch?v=BaFMov--UMM
No full textInterview pour la Chaine YouTube Imaginaire celtiqu
A Multimarker Approach to Identify Microbial Bioindicators for Coral Reef Health Monitoring—Case Study in La Réunion Island
No full textInternational audienceThe marine microbiome arouses an increasing interest, aimed at better understanding coral reef biodiversity, coral resilience, and identifying bioindicators of ecosystem health. The present study is a microbiome mining of three environmentally contrasted sites along the Hermitage fringing reef of La Réunion Island (Western Indian Ocean). This mining aims to identify bioindicators of reef health to assist managers in preserving the fringing reefs of La Réunion. The watersheds of the fringing reefs are small, steeply sloped, and are impacted by human activities with significant land use changes and hydrological modifications along the coast and up to mid-altitudes. Sediment, seawater, and coral rubble were sampled in austral summer and winter at each site. For each compartment, bacterial, fungal, microalgal, and protist communities were characterized by high throughput DNA sequencing methodology. Results show that the reef microbiome composition varied greatly with seasons and reef compartments, but variations were different among targeted markers. No significant variation among sites was observed. Relevant bioindicators were highlighted per taxonomic groups such as the Firmicutes:Bacteroidota ratio (8.4%:7.0%), the genera Vibrio (25.2%) and Photobacterium (12.5%) dominating bacteria; the Ascomycota:Basidiomycota ratio (63.1%:36.1%), the genera Aspergillus (40.9%) and Cladosporium (16.2%) dominating fungi; the genus Ostreobium (81.5%) in Chlorophyta taxon for microalgae; and the groups of Dinoflagellata (63.3%) and Diatomea (22.6%) within the protista comprising two dominant genera: Symbiodinium (41.7%) and Pelagodinium (27.8%). This study highlights that the identified bioindicators, mainly in seawater and sediment reef compartments, could be targeted by reef conservation stakeholders to better monitor La Réunion Island's reef state of health and to improve management plans. KeywordsMicrobiome • Bioindicators • Fringing coral reef • La Réunion Island * Philippe Jourand</div
: Crim. 9 janv. 2025, n<sup>os</sup> 23-84.535 et 23-86.226 (deux arrêts)
No full textInternational audienceEn cas d’atteinte alléguée à la liberté d’expression, il appartient au juge, après s’être assuré, dans l’affaire soumise, du lien direct entre le comportement incriminé et la liberté d’expression sur un sujet d’intérêt général, de vérifier le caractère proportionné de la déclaration de culpabilité, puis de la peine. Un tel contrôle nécessite un examen d’ensemble, devant prendre en compte, entre autres éléments, les circonstances des faits, la gravité du dommage ou du trouble éventuellement causé
DNA methylation landscapes before and after Pacific Oyster Mortality Syndrome are different within and between resistant and susceptible Magallana gigas
No full textInternational audiencePacific oysters face recurring outbreaks of Pacific Oyster Mortality Syndrome (POMS), a polymicrobial multifactorial disease. Although this interaction is increasingly understood, the role of epigenetics (e.g., DNA methylation) appears to be of fundamental importance because of its ability to shape oyster resistance/susceptibility and respond to environmental triggers, including infections. In this context, we comprehensively characterized basal (no infection) and POMS-induced changes in the methylome of resistant and susceptible oysters, focusing on the gills and mantle. Our analysis identified differentially methylated regions (DMRs) that revealed distinct methylation patterns uniquely associated with the susceptible or resistant phenotypes in each tissue. Enrichment analysis of genes bearing DMRs highlighted that these epigenetic changes were specifically linked to immunity, signaling, metabolism, and transport. Notably, 31 genes with well-known immune functions were differentially methylated after POMS, with contrasting methylation patterns between the phenotypes. Based on the methylome differences between phenotypes, we identified a set of candidate epibiomarkers that could characterize whether an oyster is resistant or susceptible (1998 candidates) and whether a site has been exposed to POMS (164 candidates). Overall, the findings provide a deeper understanding of the molecular in teractions between oysters and POMS infection, opening new questions about the broader implications of epigenetic mechanisms in host-pathogen dynamics and offering promising strategies for mitigating the impacts of this devastating disease. Beyond its biological aspects, this study provides insights into potential epigenetic biomarkers for POMS disease management and targets for enhancing oyster health and productivity
Assessing physical activity/behavior of adolescents living in the Pacific with accelerometer data: 231 GENEActiv records in New Caledonia
No full textInternational audienceThis paper presents a dataset related to the physical activity behavior of 206 adolescents (107 females and 99 males) from 11 to 16 years old and 25 adults (13 females and 12 males) living in rural (77 adolescents and 15 adults) and urban (129 adolescents and 10 adults) parts of New Caledonia, an archipelago of the South Pacific. Physical behavior was assessed through 60-Hz triaxial GENEActiv accelerometers worn for 5 to 7 consecutive days between July 2018 and April 2019. Participants were randomly recruited at school and trained staff fitted the devices on the nondominant wrist, at which time all were reminded of the expectations while wearing the device.The dataset contains restricted raw .bin accelerometer data provided by the GENEActiv software and open 1-second epoch .csv accelerometer data derived from the .bin files with an R script, provided in the repositories as well. Similarly, there is open information (age range and sex) and restricted information (age in months, place of living, declared cultural community and socioeconomic status) about the participants.The paper describes the file contents, describes the participants involved when collecting this dataset, and gives examples of how the data can be processed to assess the physical behavior of these participants.This high-quality dataset contains diverse sociodemographic information about the participants, which will enable the determination of correlations with their physical behavior. Moreover, since raw data with high granularity and continuous information is provided, studies interested in data processing and testing new methods on time series analyses can use the dataset
Consommation de boissons sucrées et facteurs associés chez les adolescents scolarisés de Nouvelle-Calédonie
No full textInfographie résumant l'article scientifique suivant : Wattelez G., Frayon S., Cavaloc Y., Cherrier S., Lerrant Y., Galy O. Sugar-Sweetened Beverage Consumption and Associated Factors in School-Going Adolescents of New Caledonia. Nutrients. 2019; 11(2):452. doi: 10.3390/nu11020452Infography related to the following scientific paper: Wattelez G., Frayon S., Cavaloc Y., Cherrier S., Lerrant Y., Galy O. Sugar-Sweetened Beverage Consumption and Associated Factors in School-Going Adolescents of New Caledonia. Nutrients. 2019; 11(2):452. doi: 10.3390/nu11020452Infographie résumant l'article scientifique suivant : Wattelez G., Frayon S., Cavaloc Y., Cherrier S., Lerrant Y., Galy O. Sugar-Sweetened Beverage Consumption and Associated Factors in School-Going Adolescents of New Caledonia. Nutrients. 2019; 11(2):452. doi: 10.3390/nu1102045