Дисертації з теми "Écosystèmes – Pacifique (océan ; ouest)"
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Barbin, Laure. "Distribution du micronecton dans le Pacifique tropical ouest : caractérisation de la structuration des écosystèmes par méthodes acoustiques." Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS139.
Повний текст джерелаPelagic ecosystems are key elements of the global oceans, hosting numerous exchanges between the euphotic surface and mesopelagic depths. This zone exhibits a high biodiversity and a complex trophic network, with micronekton as a central component. This compartment comprises organisms measuring between 2 and 20 cm and encompasses a wide variety of species, including fish, crustaceans, molluscs, and gelatinous organisms (such as jellyfish, pyrosomes, salps). Micronekton serves as the primary food source for top predators like tuna, marine mammals, and seabirds and is predominantly feeding on zooplankton, thus occupying a central position in the trophic network. Additionally, some micronekton species undertake a diel migration between surface and depths, known as the nycthemeral migration, occurring with each solar cycle: organisms residing in deep mesopelagic layers during the day (>300m) ascend to the surface at sunset and vice versa at dawn. This vertical migration, observed in all oceans, is one of the largest global migrations. Its substantial biomass on a global scale, central role in the trophic network, and migratory behavior contributing to oceanic biogeochemical fluxes make micronekton an indispensable element in the study of pelagic ecosystems. This thesis investigates micronekton in the tropical Pacific through three main axes: 1) observation methods and abundance estimation, 2) improvement through recent technologies, particularly broadband acoustic profilers, and 3) characterization of micronekton distribution at the Pacific scale by defining ecosystems linked to environmental variables. Axis 1) initially examines micronekton observation methods, their respective biases, and their complementary nature. By focusing on acoustic-trawl measurements in the southwest tropical Pacific, we compare micronekton abundance estimates obtained through trawling and acoustics to estimate the difference of abundance obtained by one and the other method at different depths. In axis 2), we explore the contribution of a broadband profiler to micronekton abundance and distribution studies, developing an echo-counting algorithm to estimate organism density by depth. The final axis 3) utilizes acoustic data collected during three WARMALIS campaigns in the western tropical Pacific to describe it at large scale. Five different ecosystems could be characterized. The spatio-temporal distribution of micronekton appears different in each of them, in relation with environmental variables (temperature, oxygen, salinity, currents, etc.). This division highlights the presence of the Warm Pool, the equatorial upwelling, and oligotrophic zones, each characterized by different vertical structuring and micronekton density. This thesis emphasizes the various biases of micronekton study methods and the utility of combining them to obtain more robust estimates. By then applying these methods to the tropical Pacific, it demonstrates the considerable variability of ecosystems on a Pacific scale. Including this spatial variability in global predictions of micronekton abundance and biomass is essential for refining estimates and understanding the link between the environment and biology. Finally, it reaffirms the need to consider micronekton for the sustainable preservation and management of oceanic ecosystems
Receveur, Aurore. "Ecologie spatiale du micronecton : distribution, diversité et importance dans la structuration de l'écosystème pélagique du Pacifique sud-ouest." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0401.
Повний текст джерелаThe New Caledonian pelagic ecosystem in the southwest Pacific contains a high diversity of predators, such as seabirds and cetaceans. The recent creation of the Natural Park of the Coral Sea created a need for solid information on the functioning of this remarkable ecosystem, particularly on the dynamics of the micronecton (organisms between 1 and 20 cm constituting food of top predators) and its central role in food webs, especially since is the most poorly understood. In this context, this PhD showed a strong influence of environment on its spatial and seasonal distribution with on average more micronekton in the south than in the north, and more in winter than in summer. The species composing the micronecton are riche in crustaceans in the north and in cephalopods and fish in the south. The micronecton abundance would tend to decrease under the influence of climate change. Finally, we showed that the spatial distribution of this group influenced the presence of six groups of predators: yellowfin tuna, albacore tuna, dolphin, dolphin, shearwater and red-footed body
Garidel-Thoron, Thibault de. "Dynamique climatique de l'Océan Pacifique ouest équatorial au cours du Pléistocène récent." Aix-Marseille 3, 2002. https://tel.archives-ouvertes.fr/tel-00008934.
Повний текст джерелаUsing planktonic foraminifera and coccolithophorids, we investigated past climate dynamics of the western equatorial Pacific warm pool (WPWP)during the Late Pleistocene. We developped a new planktonic foraminifera transfer function, not biased by the ecosystem structure. Using this method, the last 185 kyrs SSTs in the WPWP oscillated between 27 and 29. 5ʿC, in agreement with alkenones estimates. The "deep" atmospheric convection over the WPWP was thus a stable feature of the Late Pleistocene climate. As revealed by nannoflora, the precession cycles appear to force a rocking of the Indo-Pacific thermocline, following an "El Niño-Southern Oscillation-like" mechanism. At millenial time-scale, the Dansgaard-Oeschger cycles were find in past changes in East Asian winter monsoon. A 1500 yrs cycle imprints this 200 kyrs monsoon record. A high-resolution record of carbon isotopic changes in the WPWP, exhibits the occurrence of large methane gas-hydrates releases during the last glacial stage
Le, Bec Nolwenn. "Reconstitution des salinités et des températures des eaux de surface dans l'océan Pacifique tropical sud-ouest au cours du dernier siècle : étude multi-traceurs d'un corail scléractiniaire massif (Porites sp.) des îles Fidji." Paris 11, 2001. http://www.theses.fr/2001PA112102.
Повний текст джерелаDeschamps, Anne. "Contribution à l'étude de la formation du bassin ouest philippin : nouvelles données sur la bordure ouest et la dorsale fossile." Montpellier 2, 2001. http://www.theses.fr/2001MON20058.
Повний текст джерелаBrunel, Jean-Pierre. "L'évaporation sous différents climats du sud-ouest Pacifique : études énergétique et isotopique." Paris 11, 1992. http://www.theses.fr/1992PA112475.
Повний текст джерелаLafoy, Yves. "Evolution géodynamique des bassins marginaux Nord-Fidjien et de Lau (Sud-Ouest Pacifique)." Brest, 1989. http://www.theses.fr/1989BRES2024.
Повний текст джерелаDurand, Pascale. "Taxonomie des bactéries oxydant les composés soufrés réduits en milieu hydrothermal profond : cas du sud-ouest Pacifique." Brest, 1992. http://www.theses.fr/1992BRES2008.
Повний текст джерелаRigolot, Patrick. "Origine et évolution du "système" ride de Nouvelle-Calédonie/Norfolk (sud-ouest pacifique) : synthèse des données de géologie et de géophysique marine : étude des marges et bassins associés." Brest, 1989. http://www.theses.fr/1989BRES2018.
Повний текст джерелаCillaurren, Espérance. "La pêche à la traîne autour des dispositifs de concentration de poissons mouillés à Vanuatu : un exemple dans le Pacifique sud-ouest." Brest, 1987. http://www.theses.fr/1987BRES2034.
Повний текст джерелаGrenier, Mélanie. "Le rôle du pacifique tropical sud-ouest dans la fertilisation du pacifique équatorial : couplage dynamique et multi-traceur." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/2070/.
Повний текст джерелаIn my thesis, I study the sources of the Equatorial Undercurrent (EUC). The EUC is composed of water masses that feed the central and eastern equatorial Pacific, an area of prime importance due to its biological productivity and its impact on climate. First, I used an ocean general circulation model (OGCM) to describe the EUC in terms of its source trajectories, transports and mean hydrological characteristics. Then, I characterized the geochemical enrichment of the water masses that feed the equatorial Pacific, the EUC waters being the main contributors to the High Nutrients - Low Chlorophyll (HNLC) area. For this purpose, I used geochemical tracers : the neodymium (Nd) isotopes and the Rare Earth Element (REE) concentrations. Finally, I coupled both approaches to quantify the geochemical evolution of the thermocline waters of the southwest Pacific
Couvelard, Xavier. "Structure et dynamique des jets barotropes créés par les îles du Pacifique Sud-Ouest." Toulouse 3, 2007. http://thesesups.ups-tlse.fr/149/.
Повний текст джерелаThe oceanic circulation entering the tropical southwest Pacific (SWP) is dominated by the broad westward flow of the South Equatorial Current (SEC), forced by the trade winds. It has been argued that the numerous islands of the SWP are able to restructure the SEC into a series of deep and narrow zonal jets, which control important pathways connecting equatorial and extra-equatorial signals. The primary objective of this study is to improve our understanding of the structure and dynamics of SWP zonal jets, giving special attention to topographic effects. Our study is based on the use of a high-resolution regional oceanic model, whose solution is compared with observations, as well as with solutions from global models and the Sverdrup relation. Our model indicates that the regional topography drives a general equatorward shift of the SEC, which is beneficial to the North Fiji, North Vanuatu and North Caledonian Jets. A depth-integrated vorticity budget shows that this topographic effect is considerably attenuated by baroclinicity and advection processes, but not to the point of total compensation as often admitted for the interior ocean. The effect of non-linear advection is to allow flow rectification of the jets fluctuations which takes the form of zonally elongated dipole circulations in the leeward side of the islands
Messié, Monique. "Contrôle de la dynamique de la biomasse phytoplanctonique dans le Pacifique tropical ouest." Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00137145.
Повний текст джерелаBendel, Valérie. "Cadre géologique et composition des minéralisations hydrothermales en contexte arrière-arc : exemple de la dorsale du bassin nord fidjien (sud ouest Pacifique)." Brest, 1993. http://www.theses.fr/1993BRES2003.
Повний текст джерелаGrenier, Melanie. "Le rôle du Pacifique Tropical Sud-Ouest dans la fertilisation du Pacifique Équatorial : couplage dynamique et multi-traceur." Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00876092.
Повний текст джерелаDuprey, Nicolas. "Variabilité climatique de deux périodes clés de l'Holocène, c. 7000-6000 et 3500-2500 BP, dans le Pacifique Sud-Ouest à partir de l'analyse d'archives biocarbonatées." Paris 6, 2012. http://www.theses.fr/2012PA066500.
Повний текст джерелаThis study aims to document the climate for two key periods of the Holocene from biocarbonated archives. The giant clam Tridacna maxima was validated as a paleoclimatic archive. Fossil specimens of this species were used to document the climatic variability in the Southwest Pacific during the early mid-Holocene – 7. 0-6. 0 ka BP – and during the Lapita migration over Remote Oceania – 3. 5-2. 5 ka BP – in addition to d18O records from fossils specimens of giant clams T. Gigas, Hippopus hippopus and fossils massive coral Porites sp. Records of Sr/Ca from Porites sp. Corals also provided paleo-SST records. The post glacial SST rise was completed at 7. 0-6. 0 ka BP and the southeastern edge of the WPWP was located in its current location. At that time the seasonal influence of the SPCZ over the SW Pacific was weaker than it is today as a result of the more northerly location of this structure. The El Niño Southern Oscillation (ENSO) variability was 25-30% weaker than today. The period when the Lapita culture at 3. 6-3. 4 ka BP, was characterized by a La Niña-like climatic mean state in the SW Pacific. The Lapita migration-phase at 3. 2-2. 7 ka BP is coincidental with a strong ENSO variability supporting that the climate had a significant role in the Lapita migration. Indeed, unstable climate may have triggered and/or promoted the development and the expansion of nomad foraging population based on marine resources as the Lapita were
Zimmermann, Gabrielle. "Variabilité morphologique et génétique des Macrobrachium (Crustacea, Decapoda, Palaemonidae) de l'Indo-ouest Pacifique : évolution des peuplements et applications à la gestion." Paris, Muséum national d'histoire naturelle, 2009. http://www.theses.fr/2009MNHN0041.
Повний текст джерелаFreshwaters of the Indo-west Pacific islands are the home of many amphihalin organisms, whose amphidromous life-cycle has evolved as an adaptation to these habitats. Among them, the decapod crustaceans of the Macrobrachium genus are represented by more than 200 species distributed in the whole inter-tropical area. Very sensitive to changes in freshwater quality and over-fishing, many of these species are endangered. Nothing is known about their morphological variability, the evolutive history of their radiation, the structuration of their populations and their dispersal modalities. Though, such steps are the starting point for setting up management and conservation measures of these fragile organisms. In a first chapter, the morphological and genetic variability of the Macrobrachium australe population from Reunion Island is explored. Within this species, it reveals a strong relationship between the shape and the environment, which may be the result of a phenotypic plasticity phenomenon. A second chapter studies the evolutive history of the Macrobrachium species in the Indian and Pacific oceans. Molecular phylogenetic analysis are used, based on the nuclear 18S fragment and the mitochondrial COI fragment. In a third chapter, the structuration of M. Australe et M. Lar within a set of Indian Ocean and Pacific Ocean islands is considered. Possible larval migrations between the islands are explored. The larval marine cycle modalities are studied, along with the spatio-temporal aspects of postlarval return to freshwaters. A synthesis of the knowledge obtained is proposed, integrating possible applications to management and perspectives
Van, den Broeck Nathalie. "Rôle du phosphate dans le déclenchement et la limitation des efflorescences planctoniques dans les eaux du Pacifique tropical Sud Ouest : évaluation des conséquences sur le cycle biogéochimique du carbone." Aix-Marseille 2, 2003. http://www.theses.fr/2003AIX22099.
Повний текст джерелаSpecq, Damien. "Prévisibilité des fortes précipitations aux échéances infra-saisonnières sur le Pacifique Sud-Ouest tropical." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0089.
Повний текст джерелаNumerical subseasonal forecasting has met growing interest in the last decade, in the wake of the Subseasonal-to-seasonal (S2S) prediction project and its forecast database. This is due to recent and significant progress in two directions: a better understanding of the sources of predictability at subseasonal timescales, and a better representation of these phenomena in numerical models. However, the ability to forecast specific climate events beyond two weeks remains quite limited and sporadic. Yet, in the southwest tropical Pacific (110°E-200°E ; 30°S-0°), rainfall is expected to exhibit some subseasonal predictability, thanks to the influence of the Madden-Julian oscillation (MJO) - which is the main driver of subseasonal climate variability at the global scale - and El Nino Southern Oscillation (ENSO) - which provides low-frequency signals. The aim of this thesis is to document the subseasonal predictability of heavy rainfall periods in the southwest tropical Pacific with state-of-the-art S2S forecasting systems. A verification framework is applied to six systems from the S2S database on a common 18-year reforecast period (1996-2013) in the austral summer season (December-January-February), when heavy rainfall is the most frequent in the region of interest. Then, two approaches are developed in order to improve the verification scores compared to those obtained initially. On the one hand, various multimodel combination methods are implemented and improve deterministic and probabilistic forecast quality. On the other hand, statistical forecasts are produced using the dynamical models' output variables. The underlying assumption of this statistical-dynamical approach is that numerical models are better at forecasting large-scale climate drivers affecting rainfall, such as ENSO and the MJO, than rainfall itself. Provided that it includes both calibration of forecast precipitation along with ENSO and MJO information, this approach leads to a significant improvement of probabilistic forecasts of heavy rainfall events. Beyond a systematic evaluation with verification scores, this thesis also assesses the ability to forecast specific heavy rainfall events several weeks in advance. For this purpose, the emphasis is laid on referenced events that occurred in New Caledonia (163°E-169°E ; 23°S- 18°S). Located in the southern part of the domain, this archipelago exhibits limited subseasonal predictability of precipitation in the S2S systems. Their specific performance on the selected single events is evaluated in light of the large-scale ENSO and MJO context. This large-scale context also enables to identify windows of opportunity, when there is increased confidence that heavy precipitation will actually occur if forecast
Gasparin, Florent. "Caractéristiques des masses d'eau, transport de masse et variabilité de la circulation océanique en mer de corail (Pacifique sud-ouest)." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1986/.
Повний текст джерелаWaters from the South Equatorial Current, the northern branch of the South Pacific subtropical gyre, have been identified as having an important contribution to climate variability and El Niño-Southern Oscillation. Initially a broad westward current extending from 2°S to 30°S, the South Equatorial Current splits upon the major archipelagos of Fiji (18°S, 180°E), Vanuatu (16°S, 168°E), New Caledonia (22°S, 165°E) and Australian coasts resulting in two main zonal jets entering the Coral Sea: the North Caledonian Jet (18°S, 180°E) and the North Vanuatu Jet (16°S, 168°E). In this work, we focus on the oceanic circulation using hydrographic data from sea cruises and we apply two inverse methods: the "inverse box model" and the "optimal multi-parametric analysis". Then, we report interannunal variability and its impacts on the Coral Sea circulation. We first study the East Caledonian Current which runs along the east coast of New Caledonia and feeds the North Caledonian Jet. Both currents extend about 100 km horizontally, to at least 1000 m depth vertically and transport 15 Sv (1 Sv = 106 m3. S-1). In the northern part, the North Vanuatu Jet is larger (~300 km) and shallower (0-500 m) and transports around 20 Sv. A part of these waters reaches Australia and supplies the Solomon Sea via its western boundary current, the New Guinea Coastal Undercurrent estimated at 30 Sv. These structures are characterized by water mass properties. Secondly, we emphasize the thermocline and intermediate waters to depict water mass pathways and mixing. In the thermocline, the New Guinea Coastal Undercurrent is mainly supplied by North Vanuatu Jet waters at the thermocline level while in the intermediate level, waters come from the North Caledonian Jet. This complementary approach shows that intermediate waters are mainly carried by deep currents and subsurface waters by the North Vanuatu Jet. In the last part, interannual variability is analyzed on the 1993-2010 period with a 1/10° numerical simulation and a proxy method based on altimetric data. Interannual variability of the South Equatorial Current mass transport follows the El Niño-Southern Oscillation with a 3-months lag. The North Vanuatu Jet leads this variability. Controlled by winds, the South Equatorial Current variability is associated with thermocline depth modulation, which involves intensification after an El Niño event (6 ±4 Sv) and a decrease after La Niña (4 ±4 Sv). We also show that temperature and salinity anomalies are the result of thermocline depth modulation
Le, Faouder Antoine. "Caractérisation géochimique (déséquilibres 230Th/238U, isotopes Sr, Nd et Pb, éléments en traces) du volcanisme de dorsale en contexte d'interaction point chaud dorsale : Cas des bassins marginaux du Sud Ouest Pacifique et de la dorsale Centrale Indienne." Brest, 2006. http://www.theses.fr/2006BRES2039.
Повний текст джерелаStudying U series disequilibria in young lavas (<10kyr) is a powerful tool for understanding magma genesis and transfer such as time constraints of melt ascent or mantle porosity. Combined trace element geochemistry, isotope composition and U series data are able to indicate source heterogeneity due to the possible input of plume-derived enriched material. Input of additional mantle material can be carried out under two forms : melt or solid transport state. A major constrain to decipher between these two mechanisms is the duration of transport. Thus, U series disequilibria can provide information about the rate of the transfer process and therefore the transport mechanism of the process. The study presented here (on lavas from the North Fiji and Lau basins and the Central Indian Ridge) is probably one of the first to constrain ridge hotspot interaction using U series disequilibria and accentuates the peculiar interest of this method
Cabioch, Guy. "Récifs frangeants quaternaires de la Grande Terre de Nouvelle-Calédonie (acifique sud-ouest) : structure interne et influences de l'eustatisme et de la tectonique." Aix-Marseille 1, 1988. http://www.theses.fr/1988AIX11138.
Повний текст джерелаSchmitt, Anaïs. "Histoire de l'expansion des récifs barrières du Sud-Ouest Pacifique au cours des dernièrs 1,5 Ma : lien entre la production carbonatée, les dépôts de turbidites et les changements environnementaux." Thesis, Nantes, 2018. http://www.theses.fr/2018NANT4066/document.
Повний текст джерелаSedimentary record from Australia eastern margin offshore the Great Reef Barrier Reef is used to better understand the dynamics of mixed margins of the Southwest Pacific, in relation to Barrier reef expansion during the Pleistocene. Significant variations are observed in the nature and frequency of the turbidites deposits in the deep sedimentary record, over the last 1.5 Ma. These variations are associated with the barrier reef expansion around 400-500 ka. Comparison with a similar sedimentary record located offshore New Caledonia show similar and nearly synchronous trend, highlights a potential common mechanism for the barrier reefs expansion in the SW Pacific region. This study further explores links between carbonate production and environmental changes which are addressed by the study of the ratio Mg/Ca in surface dwelling planktic foraminifera, a proxy for sea surface temperatures reconstruction. Single foraminifera analysis were also measured to quantify the range of temperature for a given period. Measurements were performed on two G. ruber morphotypes known to calcify at different depths. Mean temperatures and seasonality do not appear to be the main control factor of the barrier expansion in the region. The vertical trend of temperatures over the last 1.5 Ma, offshore the Great Barrier Reef and New Caledonia, seems to be associated with hydrodynamic changes of the Coral Sea
Gélin, Pauline. "Délimitation d'espèces et connectivité chez les coraux du genre Pocillopora dans l'Indo-Pacifique." Thesis, La Réunion, 2016. http://www.theses.fr/2016LARE0041/document.
Повний текст джерелаThis work focuses on the connectivity among populations of the coral genus Pocillopora in the Southwestern Indian Ocean and the Southwestern Pacific Ocean. These corals are widely distributed throughout the tropical fringe of the Indian and Pacific oceans. Traditionally, species were identified on the basis of morphological criteria [17 species described in Veron (2000)]. Different studies using genetic data revealed that the delimitation of species was sometimes blurred in these corals. Thus, in this work, the use of species delineation methods from mitochondrial (ABGD, GMYC, PTP) and nuclear (haplowebs) DNA, 16 primary species hypotheses (PSH) were identified. These PSHs were then confronted to assignment tests from microsatellite loci, revealing a minimum of 18 secondary species hypotheses (SSH). Once the species hypotheses are defined, it is possible to conduct connectivity studies. In this work, two SSHs with different ecologies were chosen to carry out these analyses. The first, Pocillopora damicornis type β (SSH05) was sampled in the lagoons and the second, Pocillopora eydouxi (SSH09) was sampled on the outer slope. The estimation of the genetic structure of the populations made possible to estimate the reproductive modes (sexual or asexual) in these two SSHs and the connectivity analyzes revealed complex structuring patterns for each of the SSHs
Duval, Sébastien. "Identifications des plaques dans le manteau en comparant les modèles tomographique et de reconstruction des plaques." Paris, Institut de physique du globe, 2012. http://www.theses.fr/2012GLOB0012.
Повний текст джерелаThe western Pacific had a complex history which can be compared with the complexity of the structures in the mantle. We combined two main sources of information to interpret these structures : the plate reconstructions from 120 Myrs to the present and the tomographic images. First, we built a model of plate motions reconstruction from 120 Myrs to present using the poles of rotation between the different plates. The poles of rotation are computed from the magnetic anomalies at the bottom of the ocean and some other geological studies. We can use them to know the motion between two plates separated by a ridge. A system of plate circuit can extend the reconstructions of plate motion between all the other pair of plates. The model is then referenced using a model of hotspots in order to obtain the absolute motion of each plate. We then built a tomographic model of the western Pacific by inverting the first arrival travel times of seismic waves generated during earthquakes. Two data sets were used in order to get the best resolution, the first dataset is coming from our own measurements of travel times and the second, which is a larger dataset, is coming from the ISC data. Then we proposed a match between the depth in the tomographic model and the plate boundaries reconstructions computed at different time. The Izanagi plate, which originaly occupied most of the north-west of the Panthalassa Ocean, was totally subducted under Japan because of the expansion of the Pacific plate. The later took the place of the Izanagi plate and subducts under the Japan nowadays. In this region, we can see two areas of high velocity anomalies separated by an area a lower velocity. We interpret these structures as the Izanagi plate and the Pacific plate separated by a ridge. The Philippine plate has rotated clockwise in association with a northward translation motion since the opening of the West Philippin basin 50 Myrs ago. This rotation made the margin between the Eurasia plate and the Pacific plate move by thousands of kilometers eastward. At the same position, we observe a spreading of the slab near the transition zone which is greater when we go further from the pole of rotation of the plate. The Tethys was an ocean between the two supercontinents of Laurasia in the north and Gondwana in the south. It closed due to the dislocation of the Gondwana continent followed by a rapid rise of the Indian plate and by the northeast motion of the Australian plate. India-Asia collision provoke the uplift of the Himalaya and the extrusion of micro-blocks forming the current Indonesia and Thailand. This extrusion was accompanied by a rapid motion of the margin, also visible in cross-sections in the tomographic model. Further east, at the north-east of New Zealand, there is a subduction which initially was the separation between the Australian plate with the Phoenix plate and later with the Pacific plate. Meanwhile, the opening of the Tasman Sea and Coral Sea caused the displacement of the margin to the east. Again, the tomographic image shows some spreading slabs associated. Using both the tomographic images and the reconstructions permit to : – find past structures like the Izanagi plate in the lower mantle ; – link the motion of the plate boundary with the spreading of slabs at the transition zone ; – constrain the position of plate boundaries
Améziane-Cominardi, Nadia. "Distribution bathymétrique des pentacrines du Pacifique occidental : essai de modélisation et d'application aux faunes du lias (problèmes de tectono-eustatisme au cours du rifting téthysien)." Lyon 1, 1989. https://tel.archives-ouvertes.fr/tel-02314185/document.
Повний текст джерелаKumar, Vandhna. "Descente d'échelle statistique du niveau de la mer pour les îles du Pacifique Sud-Ouest : une approche de régression linéaire multiple." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30234.
Повний текст джерелаSea level rise is a growing concern in the islands of the western Pacific. Over the altimetry era (1993-present), sea level rise rates in the western tropical Pacific were amongst the highest recorded across the world ocean, reaching up to 3-4 times the global mean. As more and more affected communities relocate to higher grounds to escape the rising seas, there is a compelling need for information on local scales to ease the adaptation and planning process. This is not a straightforward process as sea level varies regionally, driven by wind and ocean circulation patterns, and the prevailing climate modes (e.g. ENSO, PDO/IPO). On local scales, substantial sea level changes can result from natural or anthropogenic induced vertical ground motion. Motivated by such concerns, this thesis focuses on developing a statistical downscaling technique, namely a multiple linear regression (MLR) model, to simulate island sea levels at selected sites in the southwest Pacific - Suva and Lautoka in Fiji, and Nouméa in New Caledonia. The model is based on the knowledge that sea level variations in the tropical Pacific are mainly thermosteric in nature (temperature-related changes in ocean water density) and that these thermosteric variations are dominated by wind-forced, westward propagating Rossby waves. The MLR experiments are conducted over the 1988-2014 study period, with a focus on interannual-to-decadal sea level variability and trend. Island sea levels are first expressed a sum of steric and mass changes. Then, a more dynamical approach using wind stress curl as a proxy for the thermosteric component is undertaken to construct the MLR model. In the latter case, island sea levels are perceived as a composite of global, regional and local components, where the second is dominant. The MLR model takes wind stress curl as the dominant regional regressor (via a Rossby wave model), and the local halosteric component (salinity-related changes in ocean water density), local wind stress, and local sea surface temperature as minor regressors. A stepwise regression function is used to isolate statistically significant regressors before calibrating the MLR model. The modeled sea level shows high agreement with observations, capturing 80% of the variance on average. Stationarity tests on the MLR model indicate that it can be applied skillfully to projections of future sea level. The statistical downscaling approach overall provides insights on key drivers of sea level variability at the selected sites, showing that while local dynamics and the global signal modulate sea level to a given extent, most of the variance is driven by regional factors. [...]
Saulia, Emmrick André. "Cyanobactéries diazotrophes du Pacifique Sud : variabilité saisonnière, caractérisation morpho-génétique/chimique et potentiel de valorisation." Electronic Thesis or Diss., Nouvelle Calédonie, 2019. http://www.theses.fr/2019NCAL0003.
Повний текст джерелаThe southwest Pacific Ocean and the waters of New Caledonia are characterized by high abundances of cyanobacteria. Among these cyanobacteria, some have the ability to fix atmospheric nitrogen (N2), and are called diazotrophic cyanobacteria. These organisms are known to contain high added value metabolites and nutrients in varying proportions, which give them potential for economic development that may be of interest to New Caledonia. Several of these cyanobacteria have been isolated in culture from the coastal and offshore waters of the Southwest Pacific, but the precise characterization of their diversity and their potential for recovery are still unknown. With a view to a better knowledge of diversity and a possible economic valuation, the objectives of this doctoral work were (i) to study the seasonal variability of the diversity / activity of diazotrophic cyanobacteria in the lagoon of Noumea, (i) to carry out a morphogenetic and proteomic characterization of indigenous strains recently isolated in culture and (iii) to evaluate their potential for valorization
Bordenave, Aurélien. "Evolution tectono-sédimentaire d’une marge obductée : l’exemple de la Nouvelle-Calédonie et de son domaine offshore (Sud-Ouest Pacifique)." Thesis, Bordeaux 3, 2019. http://www.theses.fr/2019BOR30024/document.
Повний текст джерелаFrom Permian to Early Cretaceous the eastern Gondwana margin was an Andine subduction context. Late Cretaceous widespread regional rifting affects this region and precedes Cretaceous to Eocene seafloor spreading of the Tasman Sea, leading to the isolation of the Zealandia continent. During the Eocene, a major tectonic event affects the entire region and leads to the obduction of mantellic material on the northeastern margin of Zealandia, which presently outcrops in New-Caledonia. The stratigraphic records of these tectonics events are accessible within the western New-Caledonian basins, in which very thick sedimentary series were deposited and are now visible through onland outcrops. The Phanerozoic eastern Gondwana subduction episode is recorded by volcanoclastic turbidites whereas rifting and post-rift phases are associated with fluvial-estuarian deposits capped by deeper deposits. The complex pre to syn-obduction phase is recorded by a very thick syntectonic gravity flow unit (“Flysch”), composed of turbidites originating from various siliciclastic and carbanoceous sources. These sedimentary series are well mapped and identified in New-Caledonia, but a detailed sedimentological description and interpretation is still lacking. Core descriptions from the CADART well which recovered 1930 meter of “flysch” series, combined with outcrop descriptions should bring new insight onto the sedimentary facies, geometries and stratigraphic architecture of these series. Following this, we focused on newly acquired data in the New Caledonian Basin, including new multichannel seismic data acquired during the TECTA cruise as well as new drilling data performed in 2017 during IODP Expedition 371. The main objective of this study is to improve the knowledge of the tectonic history of New Caledonia, from these sedimentary records. On a fundamental aspect, this study will allow to better understand the obduction mechanisms. In addition, this study should provide new information on the potential petroleum system of New-Caledonian basins
Regoli, Fabienne. "Diversité cryptique du zooplancton carbonaté et réponse aux changements globaux du pléistocène à l'anthropocène." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4330.
Повний текст джерелаThe Equatorial West Pacific thermocline dynamic is strongly modulated by climatic phenomenon as the ENSO and the Indo Asiatic monsoon. Here we use fossils of two morphotypes of the same planktonic foraminifera species, Globigerinoides ruber, from the Southern edge of the Western Equatorial Pacific as proxy of paleostratification, in order to track climate changes since the last 800 000 years. Our results show a regular beating of the Equatorial Pacific thermocline in response to Glacial/ Interglacial changes connected to the high latitudes. During glacials, the reinforced South subtropical gyre increases the advection of cold waters from the Antarctic to the West Pacific. This mechanism was progressively intensified by the increasing obliquity amplitude since 800 000 years. The morphometric study of the two morphotypes of Globigerinoides ruber indicates that the test shape responses to environmental changes at Glacial/Interglacial time scale. Furthermore these results suggest that those two populations have distinct environmental requirements, allowing to uses them as proxy of stratification. The mono-morphotypic calibration for Mg/Ca derived-paleotemperatures indicates that there is no specific thermodependance of magnesium between the two morphotypes
Chuk, Hen Shun Nomenjanahary Lalaina. "Le juge face à la convention d’arbitrage dans les pays du Sud de l’océan Indien : Madagascar, Maurice, Comores (OHADA), La Réunion et Mayotte (France)." Thesis, Paris 10, 2019. http://www.theses.fr/2019PA100135.
Повний текст джерелаArbitration is an alternative to judicial proceedings. The arbitration agreement has two effects, first it grants jurisdiction to the arbitral tribunal and, second, it excludes the state judge. However, this eviction of national jurisdictions has limits. Some circumstances require the intervention of the state judge.In such cases, he has a delicate balance to achieve. He intervenes beside or within a procedure that shall in essence be held elsewhere. Through a comparative study of arbitration laws and practices in the Southern Indian Ocean, the thesis draws the wavering line between helpful assistance and obstructing interference.In the first part, the study focuses on arbitration practices in the region, and more particularly on how national laws address arbitration agreement. Then, the analysis deals with the negative effect of competence-competence and the obligation of national courts to refer the parties to arbitration.In the second part, the thesis focuses, firstly, on the judge’s assistance to solve difficulties throughout the constitution phase of the arbitral tribunal and, secondly, on its support for interim measures before or during the arbitral proceedings.In this part of the world, there are modern laws governing interactions between national courts and arbitration. In practice, difficulties arise due to a mistrust that would explain why arbitration does not develop in some of the studied countries
Szitkar, Florent. "Signature magnétique des sites hydrothermaux dans différents environnements : contributions des données de haute résolution." Paris, Institut de physique du globe, 2013. http://www.theses.fr/2013GLOB0005.
Повний текст джерелаFont, Yvonne. "Contribution à l'étude de la terminaison ouest de la subduction des Ryukyus au niveau de la collision active arc-continent à Taiwan : apports de la sismique réflexion et de la relocalisation hypocentrale." Montpellier 2, 2001. http://www.theses.fr/2001MON20204.
Повний текст джерелаTilliette, Chloé. "Influence du fer et autres éléments traces issus des sources hydrothermales peu profondes sur la biogéochimie marine dans le Pacifique Sud-Ouest." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS046.
Повний текст джерелаThe Western Tropical South Pacific Ocean has been identified as a hotspot for dinitrogen (N2) fixation by diazotrophic organisms, with some of the highest rates recorded in the global ocean. The success of these species relies on non-limiting concentrations of dissolved iron (DFe) in the photic layer of the region, whose origin remains unclear. In this thesis work, the distribution of DFe was studied along a 6100-km transect from Noumea to the gyre waters, crossing the Lau Basin and the Tonga Arc (175°E to 166°W, along 19-21°S). Combined with an optimal multiparametric water mass analysis, DFe anomalies were determined over the transect area, the most notable being present along the Tonga Arc. The results demonstrated that water masses of remote origin entering the Lau Basin could not explain the concentrations observed at the surface in this region, leading to the confident conclusion that DFe originates from shallow hydrothermal sources present along the arc. Although a non-negligeable portion of this DFe input is transported over long distances, a large majority is rapidly removed near the sources through a variety of processes highlighted by a box model. Besides iron, hydrothermal fluids are enriched in numerous other metals that may be toxic to organisms. These fluids, introduced directly into the photic layer, could have an impact on phytoplankton. Their effect was evaluated in an innovative experiment during which natural plankton communities were subjected to an enrichment gradient of hydrothermal fluids. Despite an initial toxic effect of a few days, hydrothermal inputs ultimately induced N2 fixation, productivity and organic matter export rates two to three times higher than those of the non-enriched control. This fertilizing effect probably results from the detoxification of the environment, rich in numerous potentially toxic elements, by resistant ecotypes able to produce strong ligands, such as thiols, limiting the bioavailability of certain metals. The additional supply of fertilizing elements by the fluids, in particular DFe, thus allowed the subsequent growth of the most sensitive species. These experimental results, faithfully reproducing the in-situ observations, confirm the involvement of shallow hydrothermal fluids in the high productivity observed in the region. Hydrothermal sources could be traced at different spatial and temporal scales through the deployment of drifting (for a few days, along the Tonga Arc) and fixed (for a year, along the Lau Ridge) sediment traps and through the coring of seafloor sediments at the trap deployment sites (geological time scale). Al-Fe-Mn tracing revealed that the lithogenic material exported at small and large spatial scales in the region originated from shallow and/or deep hydrothermal sources located along the Tonga Arc. This hydrothermal signature has also been detected in the seafloor sediments, particularly in the vicinity of the Lau Ridge where the presence of a major active source is strongly suspected. Finally, the similar patterns observed for the export of biological and hydrothermal particles suggest that surface production is closely linked to hydrothermal inputs into the photic layer. In conclusion, this thesis work has demonstrated the influence of shallow hydrothermal sources on the fate of trace elements, particularly iron, in the water column and seafloor sediments, and their link to biological productivity in the Western Tropical South Pacific region
Duprey, Nicolas. "Variabilité climatique de deux périodes clés de l'Holocène, c. 7000-6000 et 3500-2500 années BP, dans le Pacifique Sud-Ouest à partir de l'analyse d'archives bio-carbonatées." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00794476.
Повний текст джерелаDeplus, Christine. "Comportement mécanique de la lithosphère océanique : cas d'une subduction complexe." Paris 11, 1987. http://www.theses.fr/1987PA112507.
Повний текст джерелаLeroux, Marie-Dominique. "Intensification rapide des cyclones tropicaux du sud-ouest de l’océan Indien (SWIO) : dynamique interne et influences externes." Thesis, La Réunion, 2012. http://www.theses.fr/2012LARE0014/document.
Повний текст джерелаDespite significant improvements in Tropical Cyclone (TC) track forecasts over the past few decades, anticipating the sudden intensity changes of TCs remains a major operational issue. The main purpose of this thesis is to analyze TC rapid intensification processes in relation with external forcing induced by upper-level troughs originating from the mid-latitudes. The impact of initial storm structure on storm evolution and prediction is also documented. An objective definition for rapid intensification in the southwest Indian Ocean is first proposed. The location and frequency of TC-trough interactions are identified, as well as TC-trough arrangements conducive to TC intensification. An interesting study case, TC Dora (2007), is chosen to run numerical simulations initialized with synthetic TC observations blended in a global analysis. The simulated TC-trough interaction is intricate with potential vorticity (PV) advection from the trough into the TC core at mid and upper levels. Vortex intensification first occurs inside the eyewall and results from PV superposition. Further intensification is associated with a subsequent secondary eyewall formation triggered by external forcing from the trough. The numerical model is able to reproduce the main features associated with outer eyewall spin-up, inner eyewall spin-down, and their effects on vortex intensity changes. Another numerical study examines typhoons in the northwest Pacific and demonstrates the critical role played by initial vortex structure in TC track and intensity prediction. Upgrading the initial specification of a TC inner-core structure in numerical models is recommended for future TC prediction improvements
Houssard, Patrick. "Variations des concentrations en mercure dans les réseaux trophiques marins de l'Océan Pacifique Sud : état des lieux, caractérisation des sources et relations avec la dynamique trophique et physique du milieu." Thesis, Nouvelle Calédonie, 2017. http://www.theses.fr/2017NCAL0001/document.
Повний текст джерелаMercury is a naturally distributed heavy metal which is characterized, under its organic form (monomethylmercury; MMHg), by its bioaccumulation in living organisms and its biomagnifications along food chains. Since the awareness of MMHg neurotoxicity, lots of research works have focused on understanding where and how MMHg is formed and transmited to marine food webs. Those questions are keys in order to anticipate how MMHg, in commercially fish species, will respond in a context of increasing mercury emissions and climate change.This work is part of this approach by studying total mercury spatial variations from muscle tissue of three tuna species: bigeye, albacore and yellowfin tuna, captured within the south Pacific Ocean. Every tuna species demonstrated a consistent and similar spatial trend, with higher total mercury concentrations in the southwest and lower concentrations in the western equatorial Pacific. This spatial trend seems to be in accordance with varying tuna diet linked to the thermal features of the water column. By combining archival tagging data and nitrogen stable isotope analysis, we showed that the deepening of bigeye tuna vertical habitat around New Caledonia might allow them to forage on deeper and MMHg enriched preys. Additionnaly, dissolved MMHg profiles in the southwest Pacific suggest higher methylation processes in the epipelagic zone leading, possibly, to higher MMHg bioavailability for marine food chains.This study highlighted the key role of tuna trophic ecology and particularly foraging depth in their MMHg exposure. Those features have to be considered in future studies evaluating food webs contamination at a spatial or temporal scale
Leroux, Marie-Dominique. "Intensification rapide des cyclones tropicaux du sud-ouest de l'océan Indien : dynamique interne et influences externes." Phd thesis, Université de la Réunion, 2012. http://tel.archives-ouvertes.fr/tel-00787099.
Повний текст джерелаGasparin, Florent. "Caractéristiques des Masses d'Eau, Transport de masse et Variabilité de la circulation océanique en mer de Corail." Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00840821.
Повний текст джерелаMaufroy, Alexandra. "Drifting Fish Aggregating Devices of the Atlantic and Indian Oceans : modalities of use, fishing efficiency and potential management." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT150/document.
Повний текст джерелаSince the mid 1990s, the use of drifting Fish Aggregating Devices (dFADs) by purse seiners, artificial objects specifically designed to aggregate fish, has become an important mean of catching tropical tunas. In recent years, the massive deployments of dFADs, as well as the massive use of tracking devices on dFADs and natural floating objects, such as GPS buoys, have raised serious concerns for tropical tuna stocks, bycatch species and pelagic ecosystem functioning. Despite these concerns, relatively little is known about the modalities of GPS buoy tracked objects use, making it difficult to assess and manage of the impacts of this fishing practice. To fill these knowledge gaps, we have analyzed GPS buoy tracks provided by the three French fishing companies operating in the Atlantic and the Indian Oceans, representing a large proportion of the floating objects monitored by the French fleet. These data were combined with multiple sources of information: logbook data, Vessel Monitoring System (VMS) tracks of French purse seiners, information on support vessels and Local Ecological Knowledge (LEK) of purse seine skippers to describe GPS buoy deployment strategies, estimate the total number of GPS buoy equipped dFADs used in the Atlantic and Indian Oceans, measure the contribution of strategies with FOBs and support vessels to the fishing efficiency of tropical tuna purse seiners, identify potential damages caused by lost dFADs and finally to propose management options for tropical tuna purse seine FOB fisheries. Results indicate clear seasonal patterns of GPS buoy deployment in the two oceans, a rapid expansion in the use of dFADs over the last 7 years with an increase of 4.2 times in the Indian Ocean and 7.0 times in the Atlantic Ocean, possible damages to fragile coastal ecosystems with 10% of GPS buoy tracks ending with a beaching event and an increased efficiency of tropical tuna purse seine fleets from 3.9% to 18.8% in the Atlantic Ocean over 2003-2014 and from 10.7% to 26.3% in the Indian Ocean. Interviews with purse seine skippers underlined the need for a more efficient management of the fishery, including the implementation of catch quotas, a limitation of the capacity of purse seine fleets and a regulation of the use of support vessels. These results represent a first step towards better assessment and management of purse seine FOB fisheries
Pang, Xiaolei. "Heat and salinity transport across the Indonesian Archipelago over the last 270,000 years : new insights into the orbital and millennial dynamics of the Indonesian Throughflow and the Intertropical Convergence Zone." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS365.
Повний текст джерелаThis work aimed at reconstructing the late Quaternary evolution of surface and thermocline temperature and ocean surface water δ¹⁸O in the Indo-Pacific Warm Pool by combining Mg/Ca-thermometry and stable oxygen isotope analyses on surface and thermocline-dwelling planktonic foraminifers retrieved from sediment cores in the eastern tropical Indian Ocean. This study allowed to re-evaluate the effects of different cleaning methods and in-situ dissolution on the Mg-thermometry of planktonic foraminifers, evidencing the need for species-dependent corrections. Then, the IPWP evolution over the last 270,000 years has been explored. Results indicate that surface water δ¹⁸O chiefly reflects lateral advection rather than local precipitation history, and suggest that surface IPWP hydrology is controlled by the latitudinal migration of the Intertropical Convergence Zone at orbital timescale as well as during abrupt northern hemisphere climatic events (i.e. Heinrich events). Ocean surface salinity in the IPWP and Agulhas leakage region varied synchronously, implying their teleconnection through oceanic and atmospheric circulation. Moreover, changes in the transport of thermocline water to the Indian Ocean by the Indonesian Throughflow (ITF) have been reconstructed. Results show that thermocline water transport was weaker during glacials (i.e. MIS 6 and 4-2) than during interglacials (MIS 7, MIS 5 and Holocene), and exerted significant influence on Indian Ocean TWT change
de, Garidel-Thoron Thibault. "Dynamique climatique de l'océan Pacifique ouest équatorial au cours du Pléistocène récent." Phd thesis, 2002. http://tel.archives-ouvertes.fr/tel-00008934.
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