HAL Collection UNC (Univ. de la Nouvelle Calédonie)
Not a member yet
7579 research outputs found
Sort by
Apprentilangue, un dispositif pour l’enseignement du vocabulaire pour des enfants de maternelle et d’école élémentaire
No full textInternational audienc
Liberté, probité, inéligibilité
No full textInternational audienceLa récente affaire dite des « assistants parlementaires du RN » a relancé le débat autour de la peine complémentaire d’inéligibilité qui a été requise contre Marine Le Pen dans ce dossier qui la met en cause pour des détournements de fonds publics au préjudice du Parlement européen. Si l’inéligibilité était prononcée tout en étant assortie, comme l’a demandé le parquet, d’une exécution provisoire, l’actuelle présidente du Rassemblement National pourrait en effet être empêchée de se présenter au futur scrutin présidentiel
Dynamics of Infragravity Waves Across the Southern Reef Barrier of Mayotte, Indian Ocean
No full textInternational audienceDue to climate change, tropical islands are being increasingly exposed to coastal hazards. Under energetic incident swells, infragravity (IG) waves can have a key contribution to extreme water levels and flooding, but their dynamics at barrier reef remains little studied. In this context, this study analyses IG wave generation mechanisms and transformations across a barrier reef to the southwest of Mayotte (Indian Ocean), combining a new comprehensive field dataset with phase resolving wave modelling. This analysis reveals that IG waves are mostly breakpoint-forced and suffer a substantial dissipation by bottom friction, particularly at low tide. Numerical experiments with reduced bottom friction representing a degraded coral reef suggest that IG waves would grow by about 20% across the reef at high tide. This study highlights the key role of coral reefs to dissipate IG waves and hence limit extreme water levels and subsequent coastal hazards.</div
Commercial Arthrospira platensis Extract Modifies the Photophysiology of Cladocopium goreaui, Coral Endosymbiont Microalgae
No full textInternational audienceArthrospira platensis extract is incorporated into sunscreen formulations for its beneficial and UV-protective properties on cultured human cells. However, its effects have not yet been assessed on non-target organisms such as endosymbiotic microalgae in coral tissue. To evaluate its effects, we investigated the photophysiology of the cultured dinoflagellate Cladocopium goreaui using PAM fluorometry (RLC, OJIP) after a 5-day exposure to different extract concentrations. Our results show that, through a hormetic effect, A. platensis enhances the performance index (Pi_Abs) at 0.018 mg L−1 by increasing the number of active reaction centers (RC/ABS) and improving electron transfer efficiency (φEo, ψEo) along the electron transport chain. Conversely, beyond 108.8 mg L−1, negative impacts appear on PSII, increasing the apparent antenna size (ABS/RC) and impairing the oxygen-evolving complex (K-peak), ultimately reducing the maximum relative electron transport rate (rETRm). This relative toxicity, obtained only for the highest concentrations, supports its potential incorporation into cosmetic formulations. This study contributes to improving the ecotoxicity assessment of cosmetic products on non-target organisms
Monitoring reef metabolism for a better management – case study of Reunion Island
No full textInternational audienceMonitoring carbon budget is a major challenge to improve coral reefs management (protection, conservation or restoration), including predictions about their fates by 2100. It requires sensors deployment, a collection of seawater samples and consideration of local factors such as tide, wind and benthic cover. This study assessed the benthic metabolic processes (organic production, respiration, calcification and calcium carbonate -CaCO3- dissolution) at three sites on the main shallow fringing reef of La Reunion Island. Autonomous sensors (current speed, temperature, salinity, PAR, dissolved oxygen -DO- and pH) were deployed during the warm and cold seasons between 2020 and 2022 and were complemented by discrete sampling of seawater for DO, pH and total alkalinity (TA) analysis. Metabolic budgets were calculated using a one-dimensional Eulerian approach of flow respirometry (study of changes in seawater chemistry along an axis, between two points, using fixed moored sensors). Due to the reef geomorphology, the variation in current orientation and its unidirectionality, spatio-temporal variability of metabolic budgets could not be related to benthic cover (Pleiades satellite images). Those factors strongly influenced variations of seawater chemistry and our ability to estimate the seawater residence time. We will show here, for instance, that reef geomorphology creates conditions for a flow re-entrainment of TA-depleted seawater (due to reef calcification activity) exiting the reef. Such TA-depleted seawater is immediately redirected towards the reef flat leading to an overestimation of daily reef net calcification rates (Gnet). At one site (33% of coral cover), Gnet was estimated at 283 mmolCaCO3.m-2.d-1. Such rate characterizes reefs with a coral cover up to 60%. Gnet accounted for 40% of reef gross primary production GPP (GPP = 726 mmolC.m-2.d-1, similar to the Indo-Pacific median) while calcification usually corresponds to 15-20% of GPP for typical coral/algal reef flats. The Eulerian method that was used in our study is a punctual approach and can be a powerful tool for monitoring coral reefs metabolism, mainly through the use of autonomous sensors. However, accurate estimations on a large spatio-temporal scale need long-term surveys and may be limited due by the difficulty of integrating the specific hydrodynamic conditions of each coral reef studied
Highlighting the resilience potential of marine protected areas in the face of coral bleaching with passive acoustic monitoring
No full textInternational audienceMarine Protected Areas (MPAs) can increase the resilience of reef communities to disturbances, playing a role in sheltering biodiversity from climate-related impacts. To determine if the protection status allows for better resilience after coral bleaching events, we recorded soundscapes of eight reefs of Moorea Island (French Polynesia). We compared the biophony of MPAs to the one of adjacent non-protected zones recorded in 2015, before two bleaching events (2016 and 2019), to the one in 2021. Then, the biophony from 2021 was compared within and outside MPAs. We hypothesize that differences in the biophony between these periods vary within and outside MPAs. The main result is an increase in the nocturnal high frequency (2–22 kHz) mass phenomena of benthic invertebrates, observed at sites with higher coral cover post-bleaching compared to pre-bleaching: nocturnal power spectral density (PSD) and peak frequency of invertebrate sounds varied between 2015 and 2021. For fish sounds, no daytime difference was observed, while nocturnal PSD was higher in 2021. These observations reflect distinct bleaching histories. High-frequency PSD measurements and the associated frequency values demonstrated strong correlation with temporal changes in coral cover. We suggest including it in long-term reef monitoring due to its complementary nature with respect to classical methods
Uncertainty in risk maps. Application to floods and marine submersion hazards
No full textInternational audienc
Diving into Diversity: Haslea berepwari (Bacillariophyceae, Naviculaceae), a new species of marine diatom from New Caledonia
No full textInternational audienceThe current article introduces and describes Haslea berepwarisp. nov., a new species of diatom discovered in the vicinity of Boulouparis, New Caledonia. Under light microscopy, H. berepwarisp. nov. strongly resembles Haslea pseudostrearia, but preliminary molecular barcoding conducted using partial 18S and rbcL genes suggested that it was a distinct species. This was confirmed first by scanning electron microscopy which showed the differences in stria densities between both species. A short-reads genome-skimming protocol applied on H. berepwarisp. nov. led us to obtain its complete mitochondrial and plastid genomes. The mitogenome is 36,572 bp in length and as already observed among other species of Haslea spp., the nad6 and nad2 genes are fused within a single open-reading frame. The plastome is 131,897 bp length, and unlike the mitogenome, it is not colinear with those of H. pseudostrearia. The results derived from the sequencing of the plastome allowed to perform a 123-gene multigene maximum likelihood phylogeny that associates H. berepwarisp. nov. to H. pseudostrearia with maximum support at the nodes but also strictly distinguishes them, suggesting a greater genetic distance between these species than what has been previously observed between other marennine-producing species