Rozprawy doktorskie na temat „Géochimie de l'environnement – Nouvelle-Calédonie”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 25 najlepszych rozpraw doktorskich naukowych na temat „Géochimie de l'environnement – Nouvelle-Calédonie”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
Klein, Perrine. "Dynamique du nickel, chrome, cuivre et zinc : du processus de compostage à l'épandage des matières fertilisantes d'origine résiduaire (MAFOR) dans des agrosystèmes de Nouvelle-Calédonie". Electronic Thesis or Diss., Nouvelle Calédonie, 2023. http://www.theses.fr/2023NCAL0004.
Pełny tekst źródłaRecycling waste-derived fertilizers (mafor) by returning them to the soil is a key practice for preserving soil organicmatter stocks while ensuring agricultural production. In New Caledonia, soils and mafor can contain high concentrationsof metallic elements (ME), notably nickel (Ni) and chromium (Cr). Copper (Cu) and zinc (Zn) are classically present inmafor. The aim of this thesis was to clarify the origin and behavior of Ni, Cr, Cu and Zn, from the production of compostfrom green waste and sewage sludge, to its use in agriculture. First, the results obtained on the compost showed thegeogenic nature of Cr and Ni, as opposed to the anthropogenic origin of Cu and Zn. The composting process doubled therapidly mobilizable Cr reservoir. Secondly, monitoring the application of compost on two contrasting soils showed thatmobilizable reservoirs depend on ME considered and soil type. Finally, the fate of available and mobilizable MEs wasstudied in an orchard with different fertilization and soil management practices. Agro-ecological practices appeared toimpact the transfer of MEs to orange trees, with facilitated uptake of (1) Ni, Cu and Zn when leguminous were cocultivated,and (2) Cr when straw was used. In the short term, the addition of compost has not resulted in any transfer of ME to the fruit. However, there is still a need for further research into the fate of MEs, with a view to establishing a local regulatory framework for the recovery of mafor
Traoré, Daouda. "Serpentinisation hydrothermale et altération latéritique des roches ultrabasiques en milieu tropical : Evolution géochimique et minéralogique de la minéralisation en platine de la Rivière des Pirogues (Nouvelle-Calédonie)". Phd thesis, Nouvelle Calédonie, 2005. http://portail-documentaire.univ-nc.nc/files/public/bu/theses_unc/TheseDaoudaTraore2005.pdf.
Pełny tekst źródłaFandeur, Dik Stefano. "Géochimie et cristallochimie du chrome au cours de l'altération de roches ultrabasiques en Nouvelle-calédonie (Massif du Koniambo)". Paris 7, 2009. http://www.theses.fr/2009PA077035.
Pełny tekst źródłaIn New-Caledonia, 35 Ma of deep weathering of ultramafic rocks yield soils strongly enriched in metallic trace elements (Ni, Co, Cr, Mn). In these soils, these large amounts of metallic trace elements constitute a significant risk for the environmental quality of this peculiar environment. Among these metallic trace elements, chromium is the most problematic because it is the most abundant (up to 3,8 wt% of Cr₂O₃), but also that showing the largest toxicity potential, depending on its redox state. After studying the redistribution of major and trace elements upon the formation of a 64 meters depth regolith in the Koniambo outcrop, a detailed study of the crystal-chemistry of chromium allowed to better understand thé behavior of this element along the weathering sequence. Initially as Cr(III), Cr is partially oxidized to Cr(VI) after redox reactions with Mn-oxyhydroxydes which accumulate at the boundary between the saprolitic and lateritic levels of the sequence. These Mn-oxyhydroxydes are also suspected to significantly increase the solubility of chromite, a mineral species usually considered as almost insoluble Regarding the very large solubility of Cr(VI), such an oxidation of Cr(III) should significantly increase the leaching of chromium along the sequence. However, mass balance with the Brimhall method indicate a quite restricted mobility for chromium, although slightly larger in the Mn-enriched levels. These observations are explained by the results of spatially-resolved analyses which show that, once oxidized by the Mn-oxyhydroxydes, Cr(VI) is re-adsorbed by the Fe-oxyhydroxydes (mainly goethite), abundant in these lateritic environments, underlying the importance of Fe-oxyhydroxydes to mitigate this leaching
Hédouin, Laetitia. "Caractérisation d'espèces bioindicatrices pour la surveillance des activités minières et la gestion de l'environnement en milieu récifal et lagonaire : application au lagon de Nouvelle-Calédonie". La Rochelle, 2006. http://www.theses.fr/2006LAROS161.
Pełny tekst źródłaMining activities constitute the major economic resource of New Caledonia. This doctoral research was realized in order to develop a programme for biomonitoring mining contamination in the New Caledonia coastal waters using marine organisms as “bioindicators”: the brown alga Lobophora variegata, the oysters Malleus regula and Isognomon isognomon and the clam Gafrarium tumidum. In this context, the bioindicative value of these four organisms for Ag, As, Cd, Co, Cr, Mn, Ni and Zn has been investigated through both laboratory and field experiments. Laboratory investigations of the bioaccumulation behaviour of the four organisms using radiotracer techniques demonstrated their high bioaccumulation and retention capacities for the contaminants tested. Moreover, the organisms respond to the most relevant criteria of a bioindicator species: the contaminant concentrations in organisms actually reflect those occurring in the environment. Field experiments showed that the analysis of contaminant concentrations in resident populations of clams, oysters and algae allowed discriminating sites according to their degree of contamination. In addition, transplantations of organisms between clean and contaminated sites indicated that the species displayed efficient bioaccumulation capacities for the contaminants in situ, and consequently, they can be used to monitor sites where the species were not naturally present. Overall, it is concluded that L. Variegata, G. Tumidum and I. Isognomon are efficient and reliable bioindicator species that may be used for active and passive biomonitoring of mining contamination in the lagoon of New Caledonia
Castellaro, Christine (1970. "Reconstitutions paléoclimatiques et paléoenvironnementales à l'Halocène et au Pléistocène terminale en Nouvelle-Calédonie et aux Seychelles (région indo-pacifique) : l'enregistrement par les coraux". Aix-Marseille 1, 1999. http://www.theses.fr/1999AIX11056.
Pełny tekst źródłaPascal, Frédéric. "Minéralogie, géochimie et dynamique sédimentaire des carbonates actuels et récents du bassin des Loyauté (Nouvelle-Calédonie, Pacifique sud-ouest)". Lyon 1, 1990. http://www.theses.fr/1990LYO10069.
Pełny tekst źródłaBréau, Ludovic. "Etude de la bioaccumulation des métaux dans quelques espèces marines tropicales : recherche de bioindicateurs de contamination et application à la surveillance de l'environnement côtier dans le lagon sud-ouest de la Nouvelle-Calédonie". La Rochelle, 2003. http://www.theses.fr/2003LAROS109.
Pełny tekst źródłaThe present work has two goals : i) identify few macrobenthic species as potential biomonitors of metal contamination of the coastal environment in New Caledonia ; ii) use jointly these species to assess bioavailable metal inputs in different areas of the SW lagoon. On the basis of biological inventories carried out in six different coastal sites, ten species (macroalgae, bivalves, echinoderms and octocorals) commonly found in these sites were selected. The study of concentration levels and geographical variability of Al, Co, Cr, Cu, Fe, Mn, Ni and Zn in soft tissues of these species showed that most of them appear to be suitable biomonitors, especially the alga Lobophora variegata and the bivalve Isognomon isognomon. Metal concentrations and spatial differences in these species revealed that two significant part of terrigenous metal inputs to the lagoon is bioavailable to these species
Quesnel, Benoît. "Altération supergène, circulation des fluides et déformation interne du massif de Koniambo, Nouvelle-Calédonie : implication sur les gisements nickélifères latéritiques". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S103/document.
Pełny tekst źródłaThe New Caledonia nickel laterite ore deposit, developed at the top of the Peridotite Nappe, hosts about 20% of the nickel resources worldwide. In order to better understand the formation of this eposit, our study, focusing on the Koniambo Massif, is not restricted to the ore zone but concerned with the whole peridotite pile. Our approach combined: i) the analysis of the internal deformation of the massif, ii) the isotopic characterization of quartz and magnesite veins which are suspected to represent by-products of the laterization process, iii) the 3D modelling of the lateritenickel ore deposit, based on a dataset of ~6000 subsurface boreholes and the study of some outcrops located into the mineralized area. The spatial and temporal evolution of the deformation associated with serpentinization is described across the ~800 m-thick rock pile of the Koniambo Massif. The upper part of the massif is densely faulted and preserves the record of two early deformation events. The first one is associated with synantigorite faults and the second one with syn-polygonal serpentine faults. The ~200m-thick serpentine sole is composed of breccias and mylonites and records pervasive tangential shearing associated with polygonal serpentine and magnesite. Thus, the serpentine sole represents a major décollement at the base of the nappe. Between the sole and the upper part of the massif, anintermediate structural level is identified, characterized by the presence of plurimetric shear zones that probably merge with the sole.The 3D characterization of the nickel distribution in the saprolite level, at both deposit and outcrop scales, gives evidence for processes implying not only vertical (as commonly assumed) but also lateral nickel redistribution. This lateral transport ismechanical or associated with fluids and leads to significant local enrichments. The isotopic characterization of the quartz veins associated with garnieritic ore shows that they formed under low temperature hydrothermal conditions. The structural and isotopic (coupling “stable isotope” and “clumped isotope thermometry”) characterization of the magnesite veins located at the serpentine sole shows that they are syn-tectonic and derived from low temperature meteoric water. As a result, we propose that active tectonics has enhanced the infiltration of the meteoric waters involved in the laterization process down to the base of the nappe
Lelabousse, Clement. "Diagenèse et reconstruction de variables environnementales à partir de la géochimie du corail Porites sp. (Nouvelle-Calédonie, Pacifique Sud-Ouest )". Phd thesis, Paris, ENSAM, 2012. http://tel.archives-ouvertes.fr/tel-00787482.
Pełny tekst źródłaJacotot, Adrien. "Dynamique du carbone dans les mangroves de Nouvelle-Calédonie : Passé, présent, futur". Thesis, Nouvelle Calédonie, 2017. http://www.theses.fr/2017NCAL0004/document.
Pełny tekst źródłaMangroves are complex and unique ecosystems that develop on intertidal areas along (sub)tropical coastlines. Due to their position, they are considered as major ecosystems in the coastal carbon cycle. Thanks to their high primary productivity, coupled with a high carbon sequestrating capacity in both biomass and soils, mangroves have been called “Blue Carbon” ecosystems. However, future climate change, and particularly increases in atmospheric CO2 concentrations, temperatures and sea-level rise, may alter its functioning. Within this context, the objectives were to (i) understand how eustatic variations may have impacted soil carbon stocks by the past, in order to better predict the effects of future sea-level rise, (ii) characterize CO2 and CH4 emissions from the soil and also from the water column within the mangrove forest, and (iii) evaluate the impact of future increase in atmospheric CO2 concentrations and in sea-level may affect the physiology of young mangrove seedlings. Increases in atmospheric CO2 concentrations will modify either the seedlings productivity and photosynthetic activity, therefore facilitating their ability to colonize new accommodation spaces due to the rising sea-level. This increase in sea-level will also have a consequent impact on soil carbon stocks, as we showed for the past eustatic variations of the late Holocene, also implying a migration of mangroves stands. Eventually, CO2 and CH4 emissions to the atmosphere were non-neglectable, particularly the one emitted from the water column
Houchot, Marie-Anne. "De l'évaluation en santé publique à une démarche de géographie de la santé". Phd thesis, Nouvelle Calédonie, 2008. http://portail-documentaire.univ-nc.nc/files/public/bu/theses_unc/TheseMarieAnneHouchot2008.pdf.
Pełny tekst źródłaMerrot, Pauline. "Géochimie, spéciation et mobilité des éléments traces métalliques (Fe, Ni, Cr et Mn) au sein des sédiments du lagon de Nouvelle-Calédonie". Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS551.pdf.
Pełny tekst źródłaNew Caledonia is covered on 33% of ultramafic rocks enriched in trace metals elements (Fe, Ni, Cr, Mn and Co). The erosion of these massifs represents an important source of these trace metals towards the lagoon, partially registered on the World List Heritage by UNESCO for its biodiversity. Understanding the geochemical cycle of these toxic trace metals is essential to evaluate the potential impacts on the biodiversity of this ecosystem. X-ray absorption spectroscopy (XAS) has shown that the contribution of iron sulfides is low, Ni and Fe are bearing by goethite and clays. These latter minerals representing the major phase for the Fe and Ni speciation were identified as chrysotile and green clays: a smectite (nontronite), a mica (glauconite) and a serpentine like a greenalite/berthierine. The clay minerals cycle and the green clay plays a major role in the Fe and Ni cycle, but also in Mn and to a lesser extent in the Cr cycles. The Mn speciation is shared by the clay minerals and the carbonates species whereas Cr is bearing by goethite and chromite inherited of laterite and in lesser extent by clay minerals. Cr is totally present under the reduced form which is the less toxic form. This absence of Cr(VI) is linked to the absence of Mn oxides in sediments avoiding the oxidation of Cr(III) to Cr(VI) and thus limits the impact on the environment. Finally, the chemical extractions of these metals show a relatively low bioavailability of trace metals except for Mn implying an effective long-term trapping for trace metals and thus limiting the environmental impacts even if the concentrations extracted are not negligible and can be threaten the biodiversity of the lagoon
Secchiari, Arianna. "Geochemical and Sr, Nd, Pb isotope investigation of the New Caledonia ophiolite". Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT173.
Pełny tekst źródłaThe New Caledonia ophiolite hosts one of the largest obducted mantle section in the world, hence providing a unique insight for the study of upper mantle processes. These mantle rocks belong to an “atypical” ophiolitic sequence, which is dominated by refractory harzburgites but it also includes minor spinel and plagioclase lherzolites. Upper crust is notably absent in the ophiolite, with the exception of some mafic-ultramafic cumulates cropping out in the southern part of the island. Although the New Caledonia ophiolite has been under investigation for decades, its ultra-depleted nature has made its characterization an analytical challenge, so that few trace element data are available, while isotopic data are completely missing. In this thesis a comprehensive geochemical study (major, trace element and Sr-Nd-Pb isotopes) of the peridotites and the associated intrusive mafic rocks from the New Caledonia ophiolite has been carried out. The peridotites are low-strain tectonites showing porphyroclastic textures. Spinel lherzolites are undepleted lithotypes, as attested by the presence of 7-8 vol.% of Na2O and Al2O3-rich clinopyroxene (up to 0.5 wt.% Na2O; 6.5 wt.% Al2O3), Fo content of olivine (88.5-90.0 mol.%) and low Cr# of spinel (13-17). Conversely, harzburgites display a refractory nature, proven by the remarkable absence of primary clinopyroxene, very high Fo content in olivine (90.9-92.9 mol.%), high Mg# in orthopyroxene (89.8-94.2) and Cr# in spinel (39-71). REE contents show abyssal-type patterns for spinel lherzolites, while harzburgites display U-shaped patterns, typical of fore-arc settings.Spinel lherzolites REE compositions are consistent with relatively low degree (8-9%) of fractional melting of a DMM source, starting in the garnet stability field. Conversely, REE models for harzburgites indicate high melting degrees (20-25%) of a DMM mantle source under spinel faies conditions, consistent with hydrous melting in forearc setting. Plagioclase lherzolites exhibit melt impregnation microtextures, Cr- and TiO2-enriched spinels and REE, Ti, Y, Zr progressive increase with respect to spinel lherzolites. Impregnation models indicate that plagioclase lherzolites may derive from spinel lherzolites by entrapment of highly depleted MORB melts in the shallow oceanic lithosphere. Mafic intrusives are olivine gabbronorites with a very refractory composition, as attested by high Fo content of olivine (87.3-88.9 mol.%), very high Mg# of clinopyroxene (87.7-92.2) and extreme anorthitic content of plagioclase (An = 90-96 mol.%). The high Mg#, low TiO2 concentrations in pyroxenes and the anorthitic composition of plagioclase point out an origin from ultra-depleted primitive magmas in a convergent setting. Geochemical trace element models show that the parental melts of gabbronorites are primitive magmas with striking depleted compositions, bearing only in part similarities with the primitive boninitic melts of Bonin Islands. The first Sr, Nd and Pb isotope data obtained for the New Caledonia ophiolite highlight the presence of DM mantle source variably modified by different processes.Nd-Sr-Pb isotopic ratios for the lherzolites (+6.98≤ƐNdi≤+10.97) indicate a DM source that suffered low-temperature hydrothermal reactions. Harzburgites are characterized by a wide variation of Sr, Nd and Pb isotopic values, extending from DM-type to EMII compositions (-0.82≤ƐNdi≤+17.55), suggesting that harzburgite source was strongly affected by subduction-related processes. Conversely, combined trace element and Sr-Nd-Pb isotopic data for gabbronorites indicate a derivation from a source with composition similar to Indian-type mantle, but affected by fluid input in subduction environment
Aupetit, Sylvine. "Rapprocher le droit de l’environnement et la réalité en Nouvelle-Calédonie : Des leviers d’amélioration de l’effectivité des normes juridiques environnementales en Nouvelle-Calédonie en faveur de la pérennité du patrimoine naturel". Thesis, Antilles, 2020. http://www.theses.fr/2020ANTI0531.
Pełny tekst źródłaHaste of biodiversity loss and climate change are notorious threat to mankind. Now, some reactions to both converging movements are a matter for human societies. We buy into the premise of politic aims in favor of the continuity of natural heritage. Law, that go with their implementation, can then be a shield for this natural heritage. Indeed, law is expected to actually channel people’s behaviour. Nevertheless, it does not always hits this target. New-Caledonia is a biodiversity hotspot where climate change can have huge impacts. It is also a very original status in the French Republic, that allows a local environmental legal system. Environmental law effectiveness is worth thinking about specifically in New-Caledonia. Two paths could lead to behaviours suiting closer to the law. First of them consists in adopting law in a way that eases its consistency and solidity, but also the harmonization of its contents with local reality. The second one aims to accompany the legal requirement with realistic sanctions, spurring on the people to respect them
Paillon, Christelle. "Etude de la connectivité entre les communautés de poissons de différents habitats du lagon de Nouvelle-Calédonie par microchimie des otolithes et de l'environnement". Thesis, Nouvelle Calédonie, 2014. http://www.theses.fr/2014NCAL0058/document.
Pełny tekst źródłaEcological connectivity is defined by organism movements between habitats.Among the tools used to measure connectivity, otolith microchemistry is the only one able toreconstruct the fish movement throughout their entire lifetime, and thus include ontogeneticmigrations. However, it is seldom used in oligotrophic environments that typically show poorchemical contrasts such as coral reefs. In this context, this study focused on otolith microchemistryof coral reef and mangrove fishes of New Caledonia. This work comprises two parts. First, amethodological part to assess the potential of otolith microchemistry in New Caledonia, with onechapter on the determination of multi-elemental signatures of habitats from the Main Island and onechapter on the relationships between environmental and otoliths microchemistries. Second, thepreviously developed methodology was applied to ecological questions, with a chapter on theimportance of mangrove on the life cycle and the spatial distribution of a Lutjanidae, Lutjanusfulviflamma, and a chapter on the lifetime movement patterns of this species. Results revealed ahigh potential of otolith microchemistry in New Caledonia with a high power of discriminationbetween mangroves and coral reefs. Relationships between environmental and otolithmicrochemistries were complex and species-specific. However, strong chemical contrasts in theenvironment were traduced in the otoliths. Results showed a strong connection between differenthabitats for L. fulviflamma, in particular between mangroves and reefs with a crucial importance ofmangroves as nursery grounds. Three different patterns of lifetime movements among habitats wereidentified. This diversity illustrates a high variability of ecological connectivity patterns amongindividuals, with a possible return to the juvenile habitat during the adult stage
Jacquet, Séverine. "Impact des apports en nutriments sur le réseau trophique planctonique du lagon sud-ouest de Nouvelle-Calédonie". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00962269.
Pełny tekst źródłaCarassou, Laure. "Les assemblages de larves de poissons deans le lagon de Nouvelle-Calédonie : structure spatio-temporelle et relations avec les facteurs abiotiques et biotiques de l'environnement". Phd thesis, Ecole pratique des hautes études - EPHE PARIS, 2008. http://tel.archives-ouvertes.fr/tel-00961365.
Pełny tekst źródłaDavid, Victor. "Pour une meilleure protection juridique de l’environnement en Nouvelle-Calédonie Innover par la construction participative du droit". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEH001/document.
Pełny tekst źródłaWhat environmental law for which society? With a method that combines a socio-anthropological examination and a legal examination, this thesis raises the question for New Caledonia, through an analysis of the recent past, contemporary difficulties and a re-foundation made possible by an evolution of legal thought and by means of tools developed recently elsewhere, which have made it possible, for example, to recognize the legal personality of elements of nature.Recognized as a global hotspot of biodiversity, with the exploitation of its huge nickel resources being a major environmental threat, how does New Caledonia, nearly 150 years after its annexation by France and its commitment for thirty years on the path of decolonization, fare in protecting its natural environment? The answer we get from the study of positive law, institutions, comparative law, speeches and field work is clear: the law applicable today in New Caledonia is the result of an exogenous rationalization of social relations. It is in fact unsuited to the cultural context of the Pacific. Balanced Man-Nature relations have been "disenchanted" by Christianization, colonization and scientific rationalization. As in many places, in New Caledonia, the sacredness that characterized these relationships has been sidelined in favor of what we have chosen to call "Noah’s complex" and which has become the foundation of any environmental policy. Our diagnosis on the limits of the current environmental law, reveals in detail the shortcomings of contemporary institutional engineering, based on political concerns for a peaceful management of a plural society and for rebalancing between communities and territories to compensate for underdevelopment due to past mistakes.However, there is a favorable context in recent years to re-enchant the legal protection of nature and its elements. Governments or judges in other latitudes recognize the legal personality of elements of nature. It is now possible to go beyond a restrictive conception of legal pluralism as the tight coexistence of irreconcilable legal orders and to advance towards a hybridization of the endogenous right and a legal order associated with the forms of the modern state. We will closely follow the co-construction, with the populations and the customary authorities, by the Loyalty Islands Province, of a negotiated environmental law and innovative principles that finally allow to fully take into account within positive law the Kanak vision of nature. Thanks to a participative method of elaboration of the law, it appears that we can reconcile the pluralisms (cultural, social, political and legal) of New Caledonia in the 21st century, within the framework of a negotiated law that is the only guarantee for the effectiveness of the law to protect the natural environment in a context of global environmental change
Juhel, Jean-Baptiste. "Base de référence, impacts anthropiques et mesure s de protection pour les requins récifaux de Nouvelle - Calédonie". Thesis, Nouvelle Calédonie, 2016. http://www.theses.fr/2016NCAL0002/document.
Pełny tekst źródłaAnthropogenic impacts on coral reefs are largely documented through changes in functional diversity, ecosystem services or resilience. Among trophic groups, apex predators in general and sharks in particular are the most sensitive to disturbance due to conservative life history traits (e.g. slow growth, late sexual maturity, low fecundity). By some estimates, shark populations have declined by >90% worldwide. To ensure the sustainability of their populations and their functional role in the reef community, appropriate management measures must be implemented. The aims of this thesis are 1) to assess reef shark populations in New Caledonia; 2) to evaluate the efficiency of stereo baited remote underwater video systems (S-BRUVS) in surveying shark distribution comparing them to underwater visual censuses (UVC) and to evaluate their potential improvements ; 3) to evaluate the impact of human proximity on diversity, abundance and behaviour of reef sharks and 4) to determine the efficiency of management measures currently in place in New Caledonia to protect reef shark populations. The results of S-BRUVS and UVC were congruent and revealed a dramatic decline of shark abundance of ~90% along the anthropogenic gradient in a country where shark fishing is historically absent. An important behavioural alteration of the grey reef shark (Carcharhinus amblyrhynchos) towards bait was highlighted. Individuals remained farther from the device, exhibited more cautious approaches, interacted less with the bait and took longer to bite it as human proximity increased. Human proximity was the main driver of the abundance decline (46 to 71%) and the behavioural alteration towards shier individuals (50 to 80%). Globally, MPAs in New Caledonia are not effective in protecting reef sharks. However, the oldest and most restrictive MPA (Merlet) hosts shark abundance close to that of some remote reefs of the archipelago and partially protect the behaviour of individuals. These results 1) emphasize the unique role of remote coral reefs as the last refuges for sharks ; 2) reveal that in absence of shark fishing, human proximity condition shark abundance and behaviour with potential ecological consequences and 3) indicate that the MPAs efficiency to ensure the protection of reef sharks is effected by their ability to exclude human presence over a sufficiently large area
Sellier, Virginie. "Développement de méthodes de traçage sédimentaire pour quantifier l'impact des mines de nickel sur l’hyper-sédimentation des rivières et l'envasement des lagons de Nouvelle-Calédonie Investigating the use of fallout and geogenic radionuclides as potential tracing properties to quantify the sources of suspended sediment in a mining catchment in New Caledonia, South Pacific Combining visible-based-colour parameters and geochemical tracers to improve sediment source discrimination in a mining catchment (New Caledonia, South Pacific Islands) Reconstructing the impact of nickel mining activities on sediment supply to the rivers and the lagoon of South Pacific Islands: lessons learnt from the Thio early mining site (New Caledonia)". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASV013.
Pełny tekst źródłaNew Caledonia, an island located in the south-western Pacific Ocean and currently the world's sixth largest producer of nickel, is facing unprecedented sedimentary pollution of its river systems. Indeed, nickel mining that started in the 1880s accelerated soil erosion and sediment transport processes. Hyper-sedimentation of the Caledonian hydro-systems has been observed after the deployment of mining activities on the archipelago. Although this phenomenon exacerbates the flooding problems experienced in these tropical regions, the sediment contributions generated by nickel mining remain unknown and are nevertheless required to guide the implementation of control measures to reduce these sediment inputs.To this end, a sediment fingerprinting study was carried out in a "pilot" catchment: the Thio River catchment (397 km²), considered as one of the first areas exploited for nickel mining in New Caledonia. Different tracers such as radionuclides, elemental geochemistry or "colour" properties were tested to trace and quantify the mining source contributions to the sediment inputs generated during two recent cyclonic flood events (tropical depression in 2015, cyclone Cook in 2017). A sediment core was also collected in the floodplain of the Thio River catchment to reconstruct the temporal evolution of these mining source contributions. The results of this study show that mining sources dominated sediment inputs with an average contribution ranging from 65-68% for the 2015 flood event to 83-88% for the 2017 flood event. The impact of the spatial variability of precipitation was highlighted to explain the variations in the contributions of these sources across the catchment. The temporal variations in the contributions of the mining sources deduced from the analysis of the sediment core were interpreted at the light of the mining history in the Thio River catchment (pre-mechanization, mechanization, post-mechanization of mining activity). The contributions of mining sources were again dominant with an average contribution along the sedimentary profile of 74 %. Once validated, this tracing method has been tested in four other catchments of New Caledonia in order to evaluate the validity of the approach in other contexts
Anso, Jérémy. "Maintien à long terme de communautés d'insectes forestiers dans un contexte de changement global : Réponses écologiques des communautés d'Orthoptères dans une succession forestière et face à la progression d'espèces invasives". Thesis, Nouvelle Calédonie, 2016. http://www.theses.fr/2016NCAL0005/document.
Pełny tekst źródłaIn the context of global biodiversity crisis at world scale, research of efficient environmental proxies are urgently required, especially in tropical island ecosystems, to better assess environment quality and select conservation priorities. In New Caledonia ecosystems, crickets have a dominant contribution to natural communities, according to their richness, diversity and range of colonized habitats. They are highly abundant in ecosystems and also have a high contribution to the soundscape with their ability to produce species-specific airborne signals. In this context of search of efficient environmental proxies, we measured the response of cricket communities in a ecological succession on utlramafic soils and facing the spread of 2 invasive ants (Wasmannia auropunctata and Anoplolepis gracilipes). Through both classical community census and bioacoustic approach through passive acoustic monitoring, we have been able to characterize specific cricket assemblage of species in each succession stage, with a striking sensitivity for biological invasions. Also, a global acoustic analysis of soundscape, greatly dominated by crickets, provides similar results without taxonomic or acoustic identification or knowledge. These preliminary results provide critical insights for the management of ecosystems, Our findings open up promising field of research in order to generalized innovative bio-indication concepts using cricket community in other cricket rich tropical regions
Marre, Jean-Baptiste. "L'évaluation économique des services écosystémiques marins et côtiers et son utilisation dans la prise de décision : cas d'étude en Nouvelle-Calédonie et en Australie". Thesis, Brest, 2014. http://www.theses.fr/2014BRES0087/document.
Pełny tekst źródłaCoastal and marine ecosystems are some of the most heavily exploited with increasing degradation. This alarming situation appeals for urgent and effective actions. The optimal balance between use and conservation of ecosystems theoretically requires all costs and benefits to be considered in decision-making, including intangible costs and benefits such as non-market use and non-use values. The broad aim of this PhD is to examine how these economic values associated with coastal and marine ecosystem services can be measured, and how the economic valuation exercise may be considered and influence management decision- making.The first analytical part of the thesis focuses on assessing non-market use and non-use values, through econometric methods. The characterization and estimation of non-use values are complex and controversial, especially when the valuation exercise is focusing on individuals who are users of the ecosystem services being considered. An original approach based on a stated preference method, namely choice experiments, is developed then empirically applied in quantifying non-market values for marine and coastal ecosystems in two areas in New Caledonia. It allows the estimation of non-use values for populations of users in an implicit way. An in-depth analysis of the individuals’ choice heuristics during the valuation exercise is also conducted, with a focus on payment non-attendance. This issue is dealt with by comparing multiple modelling approaches in terms of: (1) inferred attendance, in relation to stated attendance; (2) attendance distribution according to several socio-economic variables; and (3) welfare estimates.After noting that the potential influence of economic valuation in decision making is unclear and largely unexplored in the literature, the second major component of this PhD aims to examine if, how and to what extent the economic valuation of ecosystem services, including measures of non-market values, influence decision-making regarding coastal and marine ecosystems management in Australia. Based on two nation-wide surveys, the perceived usefulness of the economic valuation of ecosystem services by the general public and decision-makers is studied, and the reasons why decision-makers may or may not fully consider economic values are elicited. Using a multi-criteria analysis, a part of the surveys also aims at examining the relative importance of different evaluation criteria (ecological, social and economic) when assessing the consequences of a hypothetical coastal development project on commercial activities, recreational activities and marine biodiversity
Cardona, Emilie. "Influence de l'environnement trophique de l'élevage en biofloc sur les performances physiologiques de la crevette Litopenaeus stylirostris : Étude de paramètres de la nutrition, de l'immunité et de la reproduction". Thesis, Nouvelle Calédonie, 2015. http://www.theses.fr/2015NCAL0001/document.
Pełny tekst źródłaBiofloc is an intensive rearing system with zero or minimal water exchange where a diverse population of microorganisms (microalgae, zooplankton and bacteria) develops in association with organic matter to form the floc particles. These particles play the double role of biological filter and dietary supplement. This dissertation aims to better understand the process of this rearing system and its interactions with the Litopenaeus stylirostris shrimp. Two specific objectives were integrated within the framework of this general objective: (i) to measure the production gain from biofloc rearing and (ii) to study the interaction between biofloc environment and shrimp and to assess its role on production performances of shrimps. Thus, our results show production gains of shrimp reared in biofloc in terms of survival, growth, reproductive performances and quality of larvae. This better performance can be explained by the contribution of natural productivity, estimated between 37 and 40%, in shrimp food. This food supplement, constantly available in the environment, provides energy, nutrients and bioactive molecules. The natural productivity represents a source of lipids, in particular of phospholipids and polyunsaturated fatty acids, which were essential for the reproduction and development of larvae during the lecitotrophic stage; these lipids were accumulated in digestive gland and eggs from females reared in biofloc. The natural food is also a glutathione source, a powerful antioxidant molecule, which contributes to strengthen antioxidant defense system of shrimps and protects lipids against peroxidation, a cause of oxidative stress. Bacteria were dominant in natural productivity of biofloc environment and contribute to shrimp food. Thus, in the last part of this dissertation, we characterized the taxonomic diversity and abundance of bacteria in biofloc environment and showed their influence on shrimp intestinal microbiota. Generally, we observed a better health of biofloc resulting in up-regulation of the studied genes involved in immunity and anti-radical defenses after oxidative stress with hydrogen peroxide. The positive effects of biofloc rearing on survival, growth and reproduction originate from food complement provided by natural productivity
Traoré, Daouda. "Serpentinisation hydrothermale et altération latéritique des roches ultrabasiques en milieu tropical : évolution géochimique et minéralogique de la minéralisation en platine de la rivière des Pirogues (Nouvelle-Calédonie)". Phd thesis, 2005. http://tel.archives-ouvertes.fr/tel-00964062.
Pełny tekst źródłaNicholson, Kirsten. "le complexe de Tangihua, Nouvelle Zélande et ses relations avec l'unité de Poya, Nouvelle Calédonie". Phd thesis, 1999. http://tel.archives-ouvertes.fr/tel-00760055.
Pełny tekst źródła