36 research outputs found
Value and monitoring of biodiversity on Moorea Island, French Polynesia: a methodological approach of terrestrial and marine ecosystems
The island of Moorea in French Polynesia is representative
of a relatively well preserved small tropical oceanic island but both its terrestrial and marine ecosystems
are currently under strong anthropogenic pressures. The terrestrial ecosystems are facing an increasing urbanization,
and the destruction and modification of their natural habitats by cultivation and forestry plantations,
accidental or intentional fires, and particularly by the invasion of alien plant and animal species. Coastal areas
and reef ecosystems are threatened by shoreline artificialization, sedimentation due to soil erosion, increasing
uses of marine and lagoon resources and frequency of coral bleaching events. A significant erosion of terrestrial
and marine biodiversity is observed on the island since the last decades. In the context of the Land Management
Plan (PGA) and Marine Area Management Plan (PGEM) recently set up in the island by local authorities,
scientific surveys and inventories were made in 2006 in order to assess the status of terrestrial biodiversity (vascular
plants) and marine biodiversity (reef fishes) and compare areas with different anthropogenic pressures.
Studies conducted on the flora and the vegetation at low and middle elevation along altitudinal transects show
that the plant invasion process is related to climatic and topographic factors, and species autoecology. The
marine study aims to compare the protected areas with control areas in order to test the effectiveness of protection
measures and to propose a streamlined monitoring protocol. A methodological study in both terrestrial
and marine ecosystems was conducted in order to propose biodiversity indicators which are crucial for decision
making in conservation and sustainable development of island biodiversity. We used Geographic Information
System (GIS) as a fast and intuitive tool for mapping indicators and their variability. This methodological
approach developed on the island of Moorea could be used as a model for other tropical islandsMoorea est une petite ßle océanique tropicale de la Polynésie française relativement bien préservée,
mais dont les Ă©cosystĂšmes terrestres et marins sont actuellement soumis Ă de fortes pressions anthropiques.
Le milieu terrestre est confronté à une urbanisation croissante, à la destruction ou à la modification des habitats
naturels pour lâextension des cultures ou des plantations forestiĂšres, aux incendies volontaires ou accidentels, et
particuliĂšrement Ă lâinvasion dâespĂšces vĂ©gĂ©tales et animales introduites. Les zones cĂŽtiĂšres et les rĂ©cifs coralliens sont menacĂ©s par de multiples perturbations telles que lâartificialisation des lignes de rivage, lâapport de sĂ©diments
dus Ă lâĂ©rosion des sols, lâaugmentation des usages des ressources marines et lagonaires et de la frĂ©quence des
phĂ©nomĂšnes de blanchissement du corail. Une Ă©rosion sensible de la biodiversitĂ© terrestre et marine de lâĂźle est
observĂ©e depuis les derniĂšres dĂ©cennies. Dans le cadre du Plan GĂ©nĂ©ral dâAmĂ©nagement (PGA) et du Plan de
Gestion de lâEspace Maritime (PGEM) mis en place par les autoritĂ©s locales, des inventaires scientifiques ont Ă©tĂ©
rĂ©alisĂ©s en 2006 dans le but dâĂ©valuer lâĂ©tat de la biodiversitĂ© terrestre (plantes vasculaires) et marine (poissons
récifaux) et de comparer des zones soumises à différentes perturbations. Les études réalisées sur la flore et la végétation
de basse et moyenne altitude le long de transects altitudinaux montrent des processus dâinvasion vĂ©gĂ©tale
différents en relation avec les facteurs climatiques, topographiques et autoécologiques des espÚces. Les études
en milieu marin visent Ă comparer des aires protĂ©gĂ©es Ă des aires tĂ©moins afin de suivre lâefficacitĂ© des mesures
de gestion. La rĂ©flexion mĂ©thodologique menĂ©e parallĂšlement sur les deux Ă©cosystĂšmes a pour but dâillustrer
différents indices de biodiversité nécessaires à la prise de décision en matiÚre de conservation ou de développement
durable de la biodiversitĂ© insulaire et de rĂ©aliser un Ă©tat de rĂ©fĂ©rence pour Ă©tablir un diagnostic sur lâĂ©tat de
la biodiversitĂ©. La reprĂ©sentation cartographique des indices Ă lâaide dâun SIG, illustrĂ©e dans cette Ă©tude avec la
richesse spécifique terrestre et marine, permet une lecture intuitive et rapide de la variabilité de cet indice dont la
restitution est basĂ©e sur une standardisation du nombre dâespĂšces. Cette approche mĂ©thodologique dĂ©veloppĂ©e sur
lâĂźle de Moorea pourrait servir de modĂšle pour dâautres Ăźles tropicale
Tectonic history of northern New Caledonia Basin from deep offshore seismic reflection: Relation to late Eocene obduction in New Caledonia, southwest Pacific
International audienceNew, high-quality multichannel seismic reflection data from the western New Caledonia offshore domain allow for the first time the direct, continuous connection of seismic reflectors between the Deep Sea Drilling Project 208 drill hole on the Lord Howe Rise and the New Caledonia Basin. A novel seismic interpretation is hence proposed for the northern New Caledonia Basin stratigraphy, which places the Eocene/Oligocene unconformity deeper than previously thought and revisits the actual thickness of the pre-Oligocene sequences. A causal link is proposed between the obduction of the South Loyalty Basin over New Caledonia (NC) and the tectonic history of the northern New Caledonia Basin. Here it is suggested that as the South Loyalty Basin was being obducted during early Oligocene times, the NC Basin subsided under the effect of the overloading and underthrusted to accommodate the compressional deformation, which resulted in (1) the uplift of the northern Fairway Ridge and (2) the sinking of the western flank of New Caledonia. This event also had repercussions farther west with the incipient subsidence of the Lord Howe Rise
Old lineage on an old island : Pixibinthus, a new cricket genus endemic to New Caledonia shed light on gryllid diversification in a hotspot of biodiversity
Few studies have focused on the early colonization of New Caledonia by insects, after the re-emergence of the main island, 37 Myr ago. Here we investigate the mode and tempo of evolution of a new endemic cricket genus, Pixibinthus, recently discovered in southern New Caledonia. First we formally describe this new monotypic genus found exclusively in the open shrubby vegetation on metalliferous soils, named 'maquis minier', unique to New Caledonia. We then reconstruct a dated molecular phylogeny based on five mitochondrial and four nuclear loci in order to establish relationships of Pixibinthus within Eneopterinae crickets. Pixibinthus is recovered as thesister clade of the endemic genus Agnotecous, mostly rainforest-dwellers. Dating results show that the island colonization by their common ancestor occurred around 34.7 Myr, shortly after New Caledonia re-emergence. Pixibinthus and Agnotecous are then one of the oldest insect lineages documented so far for New Caledonia. This discovery highlights for the first time two clear-cut ecological specializations between sister clades, as Agnotecous is mainly found in rainforests with 19 species, whereas Pixibinthus is found in open habitats with a single documented species. The preference of Pixibinthus for open habitats and of Agnotecous for forest habitats nicely fits an acoustic specialization, either explained by differences in body size or in acoustic properties of their respective habitats. We hypothesize that landscape dynamics, linked to major past climatic events and recent change in fire regimes are possible causes for both present-day low diversity and rarity in genus Pixibinthus. The unique evolutionary history of this old New Caledonian lineage stresses the importance to increase our knowledge on the faunal biodiversity of 'maquis minier', in order to better understand the origin and past dynamics of New Caledonian biota
L'Ă©ducation Ă la culture informationnelle
La publication des actes du colloque international L'Ă©ducation Ă la culture informationnelle (Lille, octobre 2008 - sous le patronage de l'Unesco) prĂ©sente les regards de chercheurs, de praticiens ou de reprĂ©sentants d'institutions sur cette notion et ouvre de larges perspectives interdisciplinaires. Le nouveau concept de « culture informationnelle » est proposĂ© par la communautĂ© internationale pour mieux apprĂ©hender la complexification actuelle des relations entre l'enseignement, l'Ă©ducation et l'information, liĂ©e au dĂ©veloppement exponentiel des technologies numĂ©riques. Quel rapport entretient l'Ă©ducation Ă l'information (information literacy) avec l'Ă©ducation aux mĂ©dias (media literacy) et l'Ă©ducation numĂ©rique (digital literacy) ? Le pĂ©rimĂštre de la « culture informationnelle » s'Ă©tend maintenant clairement au-delĂ du monde de la documentation et des bibliothĂšques. La notion mĂȘme doit ĂȘtre prĂ©cisĂ©e, revue, alors que les pratiques continuent d'Ă©voluer. Une place importante est consacrĂ©e dans l'ouvrage Ă l'analyse comparĂ©e des approches thĂ©oriques et de plusieurs expĂ©riences menĂ©es dans diffĂ©rents pays