HAL Collection UNC (Univ. de la Nouvelle Calédonie)
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Snapshots of coral reef biodiversity and challenges in a time of crisis
No full textInternational audienceCoral reefs are sanctuaries for a large portion of our planet’s biodiversity, but their rapid decline begs critical questions about what exactly is being lost, what are the driving forces that determine decline or resilience, and what are the implications for life on Earth. To address these questions, we synthesize the state of knowledge on the diversity of coral reef life forms at different scales of biological and ecological organization, encompassing variability in genes, biomolecules, cells, organs, organisms, populations, communities, ecosystems, socio-ecosystems, and biogeoclimatic systems, with a particular focus on French tropical overseas. We discuss research pathways to address knowledge gaps in various scientific disciplines, covering genetics (genomics, transcriptomics, proteomics, metabolomics), morphology, ethology, bio-acoustics, demography, functional ecology, macro-ecology, landscape ecology, human and social sciences, bioclimatology, and their cross-disciplinary interactions. Based on contributions from a team of coral reef experts working in coral reef regions spread around the world, our synthesis supports a better understanding of the various dimensions of coral reef biodiversity and proposes future research orientations for improving our knowledge of nature and its preservation. Given the rapid decline of coral reefs, and how much is still unknown, this work underscores the urgency of cross-scale biodiversity investigations for a systemic understanding of the drivers of biodiversity distribution and dynamics
Global patterns and drivers of untracked industrial fishing in coastal marine protected areas
No full textPublisher: American Association for the Advancement of ScienceInternational audienceMarine protected areas (MPAs) are expanding worldwide, but industrial fishing within their boundaries remains poorly understood. By combining vessel Global Positioning System data with satellite imagery, we detected industrial fishing in 47% of coastal MPAs worldwide between 2022 and 2024, with two-thirds of vessel detections (67%) untracked by public monitoring. These untracked vessels were most prevalent (80%) in MPAs with the most restrictive management category, which aims to prohibit all extractive activities. The presence and density of fishing vessels were mainly driven by the size and remoteness of MPAs rather than their management category itself. Including untracked vessels increased estimated fishing effort within MPAs by 28%, to an average of 4 hours per square kilometer per year. These results highlight the continued presence of industrial fishing vessels in MPAs and an important gap in our understanding of fishing pressure on protected areas worldwide
L'océan, patrimoine culturel du pays Né kwiè pu morü
No full textL'océan est un espace à forte valeur patrimoniale pour tous les Calédoniens. Pour les Kanak, il est essentiel en raison de sa richesse en faune et en flore et il se situeau coeur de la conception du monde et de l'organisation des sociétés. Plus largement, la majorité des peuples océaniens pensent leur origine mythologique commeissue de la mer. Porteur et révélateur de liens sociaux, de pratiques de pêche et de navigation, de savoirs traditionnels et de relations intimes au monde naturel, l'océanest donc partie intégrante de la société. La relation à l'océan constitue donc un patrimoine fondamental de l'identité du pays. L'ambition de ce chapitre est de rendrecompte, d'une part, de la relation du peuple kanak à l'océan et, d'autre part, du tissage ou du maillage serré qui se crée dans la durée avec tous les autres,humains et non-humains du pays et de la région. Le parc naturel de la mer de Corail, immensité océanique peu fréquentée aujourd'hui, présente toujours un intérêtmajeur pour les différentes communautés de la Nouvelle-Calédonie, qui l'appréhendent depuis leurs lieux de vie
The Comoros in need of sand
No full textOver the past 30 years, coastlines in the Comoros have undergone widespread erosion. At the same time, more and more sand is being removed, changing beach dynamics
Consistent Unimodal Body Length Distributions in Hundreds of Reef Fishes Across Diverse Life Histories
No full textInternational audienceAnimal body size distributions result from interactions of growth, mortality and recruitment. In ecology and fisheries science, theoretical models of fish body size distributions are widely used but rely on life‐history parameters—growth coefficient (K) and natural mortality rate (M)—that remain unknown for most species and are challenging to estimate. Analysing data from underwater visual surveys and exhaustive sampling, representing 3068 populations across 797 species of shallow‐water, mostly unfished marine fishes, we demonstrate that post‐recruitment body length distributions exhibit a consistent unimodal shape across species and populations. When scaled to the mean body length, these distributions are strikingly similar across all teleost and elasmobranch species, with diverse life histories and maximum body sizes ranging from 1 cm to 3 m. Observed size structure can be approximated by a truncated normal distribution with a coefficient of variation of ~0.34 (SE = 0.002). Such consistent observed body size distributions could be aligned with Beverton–Holt population dynamics theory, if assuming an M/K ratio of ~1.5 and logistic observational selectivity with 50% detectability at ~40% of maximum body length. Alternatively, observed distributions could reflect deviations from theoretical expectations, and reconciling the unimodal distributions with theory may require relaxing some model assumptions, such as continuous recruitment, constant density‐independent growth or constant natural mortality. Overall, the consistency of population‐ and species‐level body length distributions means that unfished size structure could be predicted from a single body size parameter. It also suggests evolutionary convergence of diverse growth and mortality processes towards a narrow range of viable outcomes
Caractérisation chimique de l’extrait d’écorce d’Alphitonia neocaledonica (Schltr.) et de ses activités anti-inflammatoires
No full textInternational audienceAlphitonia neocaledonica (Schltr.) Guillaumin is a small forest tree endemic of New Caledonia traditionally used to treat rheumatic pain and dermatoses. Very few studies described biological activities and phytochemical composition of this plant. This study aims to investigate the anti‐inflammatory and anti‐gout activities of A. neocaledonica bark extract (ANBE) and its chemical composition. Lipopolysaccharide (LPS)‐induced phorbol 12‐myristate 13‐acetate (PMA)‐differentiated THP‐1 macrophages and LPS/monosodium urate (MSU)‐treated THP‐1 model reproducing gout in vitro were used. Chemical analyses were undertaken using liquid chromatography–high resolution mass spectrometry (LC–HRMS) approaches. Dose‐dependent inhibitory effects of ANBE on inflammatory cytokines interleukin‐(IL‐)1β, IL‐6, and tumor necrosis factor‐α (TNF‐α) were observed. Inhibition of LPS/MSU‐dependent IL‐1β at 1 and 10 µg/mL was also reported. Chemical analyses by LC–HRMS allowed us to putatively identify some features such as epigallocatechin, iridoid‐ and flavonoid‐glycosides, oligopeptides, and triterpenoids in ANBE. These results provide some cues in favor of traditional uses of ANBE and support the need of further bioactivities and chemical investigations
Distributions of outputs given subsets of inputs and dependent generalized sensitivity indices
No full textBetter understanding mathematical and numerical models often requires investigating the impacts of inputs on the model outputs as well as interactions. Quantifying such eects for models with non-independent input variables (NIVs) relies on conditional distributions of the outputs given every subset of inputs. In this paper, by rstly providing additional dependency models of NIVs, functional outputs are composed by dependency models (yielding equivalent representations of outputs) to derive distributions of outputs conditional on inputs. We then provide an algorithm for selecting the necessary and sucient equivalent representations that allow for obtaining all the conditional distributions of outputs given every subset of inputs, and for assessing the main, total and interaction eects (i.e., indices) of every subset of NIVs. Unbiased estimators of covariances of sensitivity functionals and consistent estimators of such indices are derived by distinguishing the case of the multivariate and/or functional outputs, including dynamic models. Finally, analytical results and numerical results are provided, including an illustration based on a dynamic model.</div
Cartographie du risque épidémiologique : le défi des données fortement déséquilibrées
No full textInternational audienceThe advent of big data collection has contributed to the development of knowledge extraction methods, but it has also introduced new challenges. One of the main issues is dealing with highly imbalanceddatasets, particularlyin class labelsforcategorical classificationtasks. This article presents a comprehensive strategy developed to address the issue of imbalanced data in a spatio-temporal epidemiological study of leptospirosis. The approach was evaluated using real data for a binary classification task, predicting the presence of contamination risk with the bacteria associated with leptospirosis, where the majority class represents 95% of the labels. By applying under-sampling, training 200 machine learning models, and using weighted predictions, our strategy achieved a balanced accuracy of 76.19%, an AUC-ROC of 83.29%, and a recall of 83.93%.L'émergence de la collecte de données massives a contribué au développement de méthodes d'extraction de connaissances, mais elle a également apporté son lot de défis. Parmi ces défis, on retrouve le problème des données fortement déséquilibrées, notamment dans les classes à prédire d'une tâche de classification catégorielle. Cet article présente une stratégie complète développée afin de pallier la problématique de données déséquilibrées dans le cadre d'une étude épidémiologique spatio-temporelle de la leptospirose. L'approche est évaluée sur des données réelles pour une tâche de classification binaire de "présence de risque" de contamination de la bactérie associée à la leptospirose, où la classe majoritaire représente environ 95% des classes à prédire. Par le sous-échantillonnage, l'entraînement de 200 modèles d'apprentissage supervisé et une prédiction pondérée, notre stratégie a atteint une justesse équilibrée de 76,19%, un AUC de 83,29% et un rappel de 83,93%
Widespread presence of metallic compounds and organic contaminants across Pacific coral reef fish
No full textInternational audienceCoral reef fishes represent an invaluable source of macro- and micro-nutrients for tropical coastal populations. However, several potentially toxic compounds may jeopardize their contribution to food security. Concentrations of metallic compounds and trace elements (MTEs), and persistent organic pollutants (POPs, including pesticides and polychlorobiphenyls PCBs), totalizing 36 contaminants, were measured in coral reef fish from several Pacific islands. The objective of this study was to describe the spatial distribution of these compounds and contaminants in order to identify potential variables explaining their distribution at a Pacific-wide scale. To achieve this, we applied Boosted Regression Trees to model species-specific and community-level contaminant and inorganic compound concentrations at the scale of the tropical Pacific Ocean. Overall, using 15 easily accessible explanatory variables, we successfully explained between 60 and 87 % of the global variation, with fish body size being the most important correlate of MTEs and POPs concentrations in reef fish. Our modeling approach allowed us to estimate and map the distribution of the community-level concentration of 19 contaminants and inorganic compounds at the scale of the equatorial and south Pacific Ocean. Spatial patterns varied significantly depending on the compound, with modeled quantities per 100 g of fish flesh generally being higher in the central and southwest Pacific than in the eastern part of the basin. These patterns were influenced by a combination of biological, environmental, anthropogenic and biogeographical variables. Overall, this approach represents an important step toward the estimation of concentrations of the main compounds on the basis of species identity and fishing location. Our results enhance our understanding of the extent of contamination in the Pacific while underscoring the urgent need for long-term and large-scale spatial monitoring of diverse compounds in this region
Comparaison des mesures par questionnaire et par accélérométrie des composantes du sommeil chez les adolescents calédoniens
No full textInfographie résumant l'article scientifique suivant : Wattelez G., Amon K. L., Forsyth R., Frayon S., Nedjar-Guerre A., Caillaud C., Galy O. Self-reported and accelerometry measures of sleep components in adolescents living in Pacific Island countries and territories: Exploring the role of sociocultural background. Child: Care, Health and Development. 2024; 50(3), e13272. doi: 10.1111/cch.13272Infography related to the following scientific paper: Wattelez G., Amon K. L., Forsyth R., Frayon S., Nedjar-Guerre A., Caillaud C., Galy O. Self-reported and accelerometry measures of sleep components in adolescents living in Pacific Island countries and territories: Exploring the role of sociocultural background. Child: Care, Health and Development. 2024; 50(3), e13272. doi: 10.1111/cch.13272Infographie résumant l'article scientifique suivant : Wattelez G., Amon K. L., Forsyth R., Frayon S., Nedjar-Guerre A., Caillaud C., Galy O. Self-reported and accelerometry measures of sleep components in adolescents living in Pacific Island countries and territories: Exploring the role of sociocultural background. Child: Care, Health and Development. 2024; 50(3), e13272. doi: 10.1111/cch.1327