HAL Portal UPF (Université de la Polynésie française)
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The French Pacific between Free France and the Vichy regime : an account of a political civil war in the French empire (1940 – 1944)
No full textInternational audienc
Behavioural response to boat noise weakens the strength of a trophic link in coral reefs
No full textInternational audienceIn oceans, the noise generated by human activities has reached phenomenal proportions, with considerable harmful effects on marine life. Measuring this impact to achieve a sustainable balance for highly vulnerable marine ecosystems, such as coral reefs, is a critical environmental policy objective. Here, we demonstrate that anthropogenic noise alters the interactions of a coral reef fish with its environment and how this behavioural response to noise impairs foraging. In situ observations on the Moorea reef revealed that the damselfish Dascyllus emamo reacts to boat passage by moving closer to its coral bommie, considerably reducing the volume of water available to search for prey. Using boat noise playback experiments in microcosms, we studied D. emamo's behaviour and modeled its functional response (FR), which is the relationship between resource use and resource density, when feeding on juvenile shrimps. Similar to field observations, noise reduced D. emamo's spatial occupancy, accompanied by a lower FR, indicating a reduction in predation independent of prey density. Overall, noise-induced behavioural changes are likely to influence predator-prey interaction dynamics and ultimately the fitness of both protagonists. While there is an urgent need to assess the effect of anthropogenic noise on coral reefs, the ecological framework of the FR approach combined with behavioural metrics provides an essential tool for evaluating the cascading effects of noise on nested ecological interactions at the community level
[Working Paper]. Sociologie de la maladie d'Alzheimer et des maladies neuro-évolutives en Polynésie française : sociologie participative des besoins des publics et de l’offre médico-sociale
No full textTerritoire autonome au sein de la République française depuis 1984, la Polynésie française (PF) conçoit et met en œuvre sa propre politique sanitaire. Peu institutionnalisé, l’accompagnement des personnes dans l’avancée en âge et la maladie repose essentiellement sur la prise en charge à domicile par les proches. Sur 27 900 habitants de plus de 65 ans (ISPF, 2022), moins de 200 résideraient aujourd’hui en structure dédiée subventionnée. La maladie d’Alzheimer et maladies apparentées semblent largement sous-déclarées dans ce contexte : moins de 500 cas sont effectivement renseignés auprès de la Caisse de Prévoyance Sociale (CPS), alors que 2 200 patients seraient probablement atteints. L’accompagnement et la prise en charge des maladies neuro-évolutives apparaît comme un enjeu important pour les prochaines décennies, dans un contexte de vieillissement populationnel rapide, amorcé au siècle dernier. Ce projet vise à fournir un état des lieux socio-sanitaire complet sur l’expérience quotidienne des maladies neuro-évolutives en PF, les freins sociologiques à leur diagnostic et les modalités de prise en charge par les services publics
La Loi Hamon vue d'outre-mer : l'exemple de la Polynésie française
No full textInternational audienceAspects répressifs du droit de la consommation polynésie
Relations taille-poids pour les espèces de poissons abondantes des récifs coralliens de huit îles de Polynésie française
No full textInternational audienceHere we present length-weight relationships (LWR) for 11 reef fish species from eight islands in French Polynesia. A total of 1,930 fish were collected from five islands in the Society Archipelago (Moorea, Tahiti, Raiatea, Huahine, Tetiaroa) and in three atolls of the Tuamotu Archipelago (Takapoto, Tikehau, and Rangiroa). These fishes span trophic levels, including planktivores, herbivores, and carnivores, and are among the most abundant species for the region. Estimates include LWRs for species never previously published or available in the literature or accessible databases. Measurements of total length (TL: 0.1 cm precision) and total weight (W: 0.01 g precision) were taken. These estimates increase the number of available and robust LWRs for coral reef fishes, providing a better understanding of patterns of growth for these species. With a particular focus on small-bodied species, among the most abundant observed in underwater visual censuses, these estimates will allow marine resource managers and local scientists to characterize fish biomass in French Polynesia with greater precision.Nous présentons ici les relations longueur-poids (LWR) pour 11 espèces de poissons de récif corallien de huit îles de Polynésie française. Au total, 1930 poissons ont été collectés dans cinq îles de l’archipel de la Société (Moorea, Tahiti, Raiatea, Huahine, Tetiaroa) et dans trois atolls de l’archipel des Tuamotu (Takapoto, Tikehau et Rangiroa). Ces poissons couvrent plusieurs niveaux trophiques, avec des planctonophages, des herbivores et des carnivores, et sont parmi les espèces les plus abondantes de la région. Les estimations comprennent des LWR pour des espèces qui n’ont jamais été publiées auparavant ou qui ne sont pas disponibles dans la littérature ou les bases de données accessibles. Les mesures de longueur totale (TL : précision de 0,1 cm) et de poids total (P : précision de 0,01 g) ont été effectuées. Ces estimations augmentent le nombre de LWR disponibles et robustes pour les poissons des récifs coralliens, ce qui permet de mieux comprendre la croissance de ces espèces. Avec un focus plus particulier sur les espèces de petite taille, parmi les plus abondantes observées lors des comptages visuels sous-marins, ces estimations permettront aux gestionnaires des ressources marines et aux scientifiques locaux de caractériser les biomasses de poissons en Polynésie française avec une plus grande précision
Benthic cyanobacterial metabolites interact to reduce coral larval survival and settlement
No full textInternational audienceBenthic cyanobacterial mats (BCMs) are becoming increasingly abundant on coral reefs worldwide. High growth rates and prolific toxin production give them the potential to cause widespread coral recruitment failure through allelopathic effects, but few studies have made the link between their toxicity for coral larvae and in situ toxin concentrations. Here we investigated the allelopathic effects of the benthic cyanobacterium Anabaena sp.1 on larvae of the coral Pocillopora acuta. This cyanobacterium produces several non-ribosomal cyclic lipopeptides of the laxaphycin family with cytotoxic properties. Therefore, we measured the concentration of laxaphycins A and B in Anabaena mats and in the water column and tested their effects on coral larvae. We found that Anabaena crude extract reduces both larval survivorship and settlement and that laxaphycin B reduces settlement. When larvae were exposed to both laxaphycins, there was a reduction in both larval survival and settlement. In the natural reef environment, laxaphycin A and B concentrations increased with increasing proximity to Anabaena mats, with concentrations being consistently above LC50 and EC50 thresholds within a 1 cm distance of the mats. This study demonstrates that laxaphycins reduce the survival and inhibit the settlement of coral larvae at concentrations found near Anabaena mats in situ. It further shows a combined effect between two cyanobacterial metabolites. As BCMs become more common, more of their secondary metabolites might be released in the water column. Their occurrence will lead to a reduction in coral recruitment rates, contributing to the continuing decline of coral reefs and shift in community structure
Challenging trophic position assessments in complex ecosystems: Calculation method, choice of baseline, trophic enrichment factors, season and feeding guild do matter: A case study from Marquesas Islands coral reefs
No full textInternational audienceAbstract Assessments of ecosystem functioning are a fundamental ecological challenge and an essential foundation for ecosystem‐based management. Species trophic position (TP) is essential to characterize food web architecture. However, despite the intuitive nature of the concept, empirically estimating TP is a challenging task due to the complexity of trophic interaction networks. Various methods are proposed to assess TPs, including using different sources of organic matter at the base of the food web (the ‘baseline’). However, it is often not clear which methodological approach and which baseline choices are the most reliable. Using an ecosystem‐wide assessment of a tropical reef (Marquesas Islands, with available data for 70 coral reef invertebrate and fish species), we tested whether different commonly used TP estimation methods yield similar results and, if not, whether it is possible to identify the most reliable method. We found significant differences in TP estimates of up to 1.7 TPs for the same species, depending on the method and the baseline used. When using bulk stable isotope data, the choice of the baseline significantly impacted TP values. Indeed, while nitrogen stable isotope (δ 15 N) values of macroalgae led to consistent TP estimates, those using phytoplankton generated unrealistically low TP estimates. The use of a conventional enrichment factor (i.e. 3.4‰) or a ‘variable’ enrichment factor (i.e. according to feeding guilds) also produced clear discrepancies between TP estimates. TPs obtained with δ 15 N values of source amino acids (compound‐specific isotope analysis) were close to those assessed with macroalgae. An opposite seasonal pattern was found, with significantly lower TPs in winter than in summer for most species, with particularly pronounced differences for lower TP species. We use the observed differences to discuss possible drivers of the diverging TP estimates and the potential ecological implications
L'obligation de proposer une intégration dans un corps d'accueil ne s'applique pas aux agents détachés pour exercer des fonctions sur une base contractuelle
No full textInternational audienceNote sous TA Marseille, 12 janvier 2024, no 210359
A new set of N isotopic reference values for monitoring Ulva green tides in coral reef ecosystems
No full textInternational audienceGreen tides occurrence has increased in coral reefs, yet few reference values have been documented to support bloom management in these ecosystems. Here, we took advantage of recent Ulva green tides that occurred in New Caledonia to (i) identify the elements limiting the growth of Ulva spp. during these blooms; and (ii) validate the use of isotopic markers for identifying sources of nutrients that generated blooms. N/P ratios highlighted a stronger limitation of algae by phosphorus than by nitrogen on sites under oceanic influence, while the proportions of N and P were optimal for algal growth at sites where green tides occurred. Macroalgae highly exposed to sewage water was characterized by higher δ15N than macroalgae collected in areas exposed to synthetic inorganic fertilizers. From these results, we established a new set of threshold values for using δ15N in Ulva species as an indicator of nitrogen source type in coral reefs
