HAL Portal UPF (Université de la Polynésie française)
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Assessing recovery potential of coral reefs in Madagascar and the effects of marine protected areas
No full textInternational audienceLarge-scale disturbances and local stressors, most notably bleaching events, sedimentation, and overfishing,impact coral reefs around Madagascar. To enhance reef resilience, managers have established several marineprotected areas (MPAs) since 1966. Here, we assess the effects of MPAs on the resilience potential of coral reefsusing a multi-factor Recovery Index (RI), based on a multi-criteria analysis: the Technique for Order Preferenceby Similarity to an Ideal Solution (TOPSIS). We sampled 18 stations, half of which in unfished areas, along threeregions (Masoala in the NE, Nosy-Be in the NW and Salary Nord in the SW) that have been affected by thebleaching event of 2016, the most recent large-scale disturbance. We found a marked variation in RI betweenregions, with Masoala having the highest RI. We suggest that these results relate to the lower frequency of seasurface temperature anomalies (SSTa) along the east coast and the combination of more frequent SSTa andhigher anthropogenic pressures on the west coast. We also found RI variation among stations; most stations withhigher RI have high juvenile coral densities, which support important coral replenishment capacities. We furthernoted a positive effect of MPAs on recovery potential at Nosy-Be. We argue that the effectiveness of MPAs inMadagascar can be increased with Locally Managed Marine Areas, which feature a strong involvement ofintended users and are often easier to manage. Our study also demonstrates that TOPSIS can be a useful tool toestimate the recovery capacities of coral assemblages and to support resilience-based conservation actions
Plastic is in the details: the impact of plastic pollution through a mesocosm experiment
No full textInternational audienceMicrobial diversity plays key role in marine ecosystems, and quantifying the impact of plastic pollution on these organisms is essential to better anticipate and manage threats to these fragile ecosystems. In nine simplified tropical ecosystems (i.e. mesocosms), we tested a concentration gradient of macroplastics reflecting the amount of plastic released by pearl farms. In each mesocosm, we collected bacterial samples from three different compartments: macroplastics, water and animals, Tridacna maxima. The objective was to test how plastic concentration influences the bacterial community, whether certain bacteria respond similarly across these compartments, and to define a threshold concentration of plastic that would impact marine bacteria. We observed that over 70 % of the variability in the bacterial community was explained by the type of sample (51.8 %) and time (19.4 %). On a finer scale, we found that the abundance of 33 bacterial genera was significantly correlated with plastic pollution, with the highest concentration (4.05 g/L) accounting for the vast majority of the signal. The occurrence of these bacterial genera increased with high plastic concentrations, suggesting imbalanced competitive relationships favoring less pollutant-sensitive genera. Some of these bacteria were shared across compartments and have known ecological functions, including plastic degradation and pathogenicity. Our results align with prior studies that warn plastics can alter microbial interactions and promote the emergence of pathogenic families
Revitalisation de la langue des signes tahitienne : étude comparative du contexte océanien et européen
No full textLe maintien d’une langue dans un territoire annexe pose la question de la naissance d’une variété langagière propre au territoire. L’éloignement géographique est moteur de développement de variations langagières. Ces dernières peuvent s’exprimer dans des variations de signes, dans la mise en place de règles grammaticales différentes ou dans la création d’un vocabulaire propre au territoire. À Tahiti, cette question demanderait un travail de recherche auprès des locuteurs afin de mener une étude comparée entre la LSF de France métropolitaine et la LS parlée sur l’île.Les recherches ont longtemps présenté l’Europe comme le berceau des langues des signes. Ces dernières se seraient ensuite implantées dans le monde, dont le Pacifique, durant la colonisation. Bien que les langues des signes aient été essentiellement étudiées en Europe et Amérique du Nord, des études sont progressivement menées sur les autres territoires par les populations concernées. Les récentes recherches mettent en avant la diversité historique des LS qui auraient été présentes dans de nombreuses cultures pré-contact. On peut ainsi citer les langues des signes aborigènes nommées iltyem iltyem qui sont encore présentes dans le Nord de l’Australie.La force des identités et la prise de position du gouvernement actuel permet de se poser la question d’une reconnaissance officielle de la langue des signes tahitienne. Les différents entretiens menés ont amené la question suivante : reconnaissance des particularités territoriales des langues des signes : dans quelle mesure les processus d’institutionnalisation de la langue des signes italienne et des différentes langues du Pacifique peuvent inspirer la Polynésie française dans la reconnaissance d’une langue des signes tahitienne
Negative parental and offspring environmental effects of macroalgae on coral recruitment are linked with alterations in the coral larval microbiome
No full textInternational audienceThe persistence of reef-building corals is threatened by macroalgal competitors leading to a major demographic bottleneck in coral recruitment. Whether parental effects exist under coral–algal competition and whether they influence offspring performance via microbiome alterations represent major gaps in our understanding of the mechanisms by which macroalgae may hinder coral recovery. We investigated the diversity, variability and composition of the microbiome of adults and larvae of the coral Pocillopora acuta and surrounding benthic substrate on algal-removed and algal-dominated bommies. We then assessed the relative influence of parental and offspring environmental effects on coral recruitment processes by reciprocally exposing coral larvae from two parental origins (algal-removed and algal-dominated bommies) to algal-removed and algal-dominated environmental conditions. Dense macroalgal assemblages impacted the microbiome composition of coral larvae. Larvae produced by parents from algal-dominated bommies were depleted in putative beneficial bacteria and enriched in opportunistic taxa. These larvae had a significantly lower survival compared to larvae from algal-removed bommies regardless of environmental conditions. In contrast, algal-induced parental and offspring environmental effects interacted to reduce the survival of coral recruits. Together our results demonstrate negative algal-induced parental and offspring environmental effects on coral recruitment that could be mediated by alterations in the offspring microbiome
L’agriculture urbaine tahitienne: Les jardins collectifs, des tiers lieux entre bienfaits sociaux et sociétaux
No full textInternational audienceA place for socialising and socialising, a community garden is a meeting place where you can extend your social network. The gardens studied have a civic and even political dimension, which means that they can be likened to ‘third places’. As part of the public realm, they are new spaces for leisure, learning, sharing, working together, innovation and entrepreneurship. With the development of community gardens in the Papeete area, this study confirms the importance of links between urban dwellers and these leisure spaces. In the words of the people we met, these gardens represent hybrid places that lie between the public and private spheres, and between collective and individual space.Espace de socialisation et de sociabilisation, un jardin collectif est un lieu de rencontre, permettant d’étendre son réseau social. Ceux étudiés sont assortis d’une dimension d’expression citoyenne, voire politique, qui revient à assimiler les jardins collectifs à des « tiers lieux ». Au sein de l’espace public, ils caractérisent de nouveaux espaces de loisirs, d’apprentissage, de partage, de travail en commun, d’innovation et d’entrepreneuriat. Face au développement des jardins collectifs dans l’agglomération de Papeete, cette étude confirme l’importance des liens entre les urbains et ces espaces de loisirs. Dans les discours des personnes rencontrées, ces jardins représentent des lieux hybrides qui se situent entre la sphère publique et privée, puis entre l’espace collectif et individuel
L'OCCIDENT FACE AUX CRISES DEPUIS LE XIXE SIÈCLE.: LE RETOUR À LA TERRE ET À LA LOCALITÉ EST L'UNE DES RÉPONSES TRADITIONNELLES AUX CRISES
No full textInternational audienceResponses to epidemics and climate change since ancient times, as well as their interpretations, ar e recurrent in times of crisis. Confronted with what may appear to be a series of global crises - health, environmental, economic and even democratic - the ideas on the virtues of what is local and rural are becoming increasingly important. We propose to put this return to locality ‘in historical perspective’. The first part of the paper presents the major events, in France, and explains the major changes in the agricultural world between the 18th and 19th centuries. The second part highlights the aesthetic, artistic, utopian and literary reactions to the ravages of industrialisation in France and England. The third part deals with the integration of nature in the city since the 18th century, and then the nostalgic aspirations for working the land since the 19th century. Finally, in these times of pandemic, we conclude this study on the current movements of degrowth, ecology and return to the local, in favour of food and collective gardens.Les réponses aux épidémies et au changement climatique depuis l'Antiquité, ainsi que leurs interprétations, sont récurrentes en temps de crise.Face à ce qui peut apparaître comme une série de crises globales - sanitaires, environnementales, économiques et même démocratiques - les réflexions sur les vertus du local et du rural prennent de plus en plus d'importance. Nous proposons de mettre ce retour au local "en perspective historique". Une première partie présente les événements majeurs qui, en France, expliquent les grandes mutations du monde agricole entre le 18e et le 19e siècle. Une deuxième partie met en lumière les réactions esthétiques, artistiques, utopiques et littéraires face aux ravages de l'industrialisation en France et en Angleterre. Une troisième partie traite de l'intégration de la nature dans la ville depuis le XVIIIe siècle, puis des aspirations nostalgiques au travail de la terre depuis le XIXe siècle. Enfin, en ces temps de pandémie, nous concluons cette étude sur les mouvements actuels de décroissance, d'écologie et de retour au local, en faveur de l'alimentation et des jardins collectifs
Ethnobotanic and genetic diversity of sugarcane in French Polynesia
No full textInternational audienceBackground: In French Polynesia, traditional tō (Saccharum officinarum) have been reexploited in the recent years to produce organic certified rum. Former botanists have described the sugarcane which were spread by Polynesians during their migrations of the Eastern Pacific. One of them, referred by botanists as Otahiti was the main cultivar grown for sugar production until the 1880s.Methods: Between 2013 and 2017, we collected 15 sugarcane accessions in the Society Islands and examined their taxonomic status to establish the correspondence with those described by former botanists. Nine morphological traits were repeatedly measured including stalk colour, tillering, stalk height, stalk diameter, and internode lengths. We also analyzed them using flow cytometry, PCR markers and in one case molecular cytogenetics.Results: The results showed 4 modern hybrids cultivars, 9 traditional S. officinarum and one intergeneric hybrid between S. officinarum and the wild genus Miscanthus floridulus, Tō 'ā'eho. Among the traditional S. officinarum sugarcane cultivars, we suggested that Polynesian sugarcane called Tō ‘irimotu and Tō re’are’a could correspond to Otahiti.Conclusions: The studies of processing characteristics also revealed the high Brix of the Tō 'ā'eho and its potential for producing rum. These types of hybrids support the hypothesis of Pacific being a satellite center of sugarcane diversity