Les travaux de thèse présentés dans ce manuscrit portent sur l'étude de quatre éponges marines issues de la zone Sud-Ouest de l'Océan Indien : Plakortis kenyensis, Theonella swinhoei, Haliclona fascigera et Fascaplysinopsis reticulata. Les travaux entrepris comprenaient l'étude chimique de ces éponges incluant l'extraction, l'isolement et l'identification des métabolites secondaires par différentes techniques chromatographiques (CLMP, CLHP...) et spectroscopiques (UV-visible, HRMS, RMN 1D et 2D...). Douze métabolites secondaires ont été isolés de ces éponges dont six de structures nouvelles, à savoir : l'acide 2,5-époxydocosan-6-én-21-ynoïque (HF1), un acide gras atypique isolé de l'éponge Haliclona fascigera ; la 8-oxo-tryptamine (FR2), la 6,6’-bis-(débromo)- gelliusine F (FR3), la 6-bromo-2’-déméthyl-3’-N-méthyl-1’,8-dihydroaplysinopsine (FR6), la 5,6-dibromo-2’- déméthyl-3’-N-méthyl-1’,8-dihydroaplysinopsine (FR7) et la 5,6-dibromo-3’-déimino-2’-déméthyl-3’-oxo-1’,8- dihydroaplysinopsine (FR8), cinq alcaloïdes indoliques isolés de l'éponge Fascaplysinopsis reticulata. La valorisation des molécules isolées a ensuite été envisagée via l'évaluation de leurs activités biologiques. Parmi les douze molécules isolées, sept ont montré une activité antipaludique, trois une activité inhibitrice du quorum sensing de la bactérie bioluminescente Vibrio harveyi et cinq une activité anti-microfouling par inhibition de l'adhésion et/ou de la croissance de souches microbiennes marines. / The work described in this manuscript concerns four sponges from the South-West Indian Ocean: Plakortis kenyensis, Theonella swinhoei, Haliclona fascigera and Fascaplysinopsis reticulata. The chemical study of the sponges including extraction, isolation and identification of secondary metabolites was undertaken using various chromatographic (MPLC, HPLC ...) and spectroscopic (UV-visible, HRMS, 1D and 2D NMR ...) techniques. Twelve secondary metabolites including six new molecules were isolated from these sponges. The new molecules are: 2,5-époxydocosan-6-en-21-ynoic acid (HF1) an unusual fatty acid isolated from the sponge Haliclona fascigera; 8-oxo-tryptamine (FR2), 6,6'-bis (debromo)-gelliusine F (FR3), 6-bromo-2'-demethyl-3'-N- methyl-1',8-dihydroaplysinopsine (FR6), 5,6-dibromo-2'-demethyl-3'-N-methyl-1',8-dihydroaplysinopsine (FR7) and 5,6-dibromo-3’-deimino-2’-demethyl-3’-oxo-1’,8-dihydroaplysinopsine (FR8), five indole alkaloids isolated from the sponge Fascaplysinopsis reticulata. The biological activities of the isolated molecules were then evaluated. Among the twelve isolated molecules, seven were active against the malaria parasite Plasmodium falciparum, three were identified as inhibitors of the quorum sensing-regulated bioluminescence in Vibrio harveyi and five, showing marine bacterial adhesion and/or growth inhibition, exhibited potential anti- microfouling activity.

The Late Cretaceous–early Paleogene is the most recent period of Earth history with a dynamic carbon cycle that experienced sustained global greenhouse warmth and can offer a valuable insight into our anthropogenically-warmer future world. Yet, knowledge of ambient climate conditions and evolution of the carbon cycle at this time, along with their relation to forcing mechanisms, are still poorly constrained. In this thesis, I examine marine sediments recovered from the South Atlantic Walvis Ridge (ODP Site 1262) and Indian Ocean Ninetyeast Ridge (IODP Site U1443 and ODP Site 758), to shed new light on the evolution of the climate and carbon cycle from the Late Maastrichtian through to the Early Eocene (~67.10–52.35 Ma). The overarching aims of this thesis are: 1) to identify the long-term trends and principle forcing mechanisms driving the climate and carbon cycle during this time period, through construction of 14.75 million-year-long, orbital-resolution (~1.5–4 kyr), stratigraphically complete, benthic stable carbon (δ13Cbenthic) and oxygen (δ18Obenthic) isotope records; 2) to investigate in more detail the climatic and carbon-cycle perturbations of the Early–Middle Paleocene (e.g., the Dan-C2 event, Latest Danian Event and the Danian/Selandian Transition Event) and place these in their proper (orbital) temporal context; 3) to investigate the Late Maastrichtian warming event and its relationship to the eruption of the Deccan Traps Large Igneous Province, as well as its role (if any) in the subsequent Cretaceous/Paleogene (K/Pg) mass extinction; 4) to provide the first orbital-resolution estimates of temperature and carbonate chemistry variability from the low latitude Indian Ocean spanning the Late Paleocene–Early Eocene, through analysis of trace element and stable isotope data from multiple foraminiferal species. Taken together, the results presented in this thesis provide a critical new insight into the dynamic evolution of the climate and carbon cycle during the greenhouse world of the early Paleogene, and shed light on the potential forcing mechanisms driving the climate and carbon cycle during this time.

L'oscillation de Madden-Julian (MJO) est la composante dominante de la variabilité intrasaisonnière dans l'atmosphère tropicale, se propageant vers l'est dans la bande équatoriale. Elle se compose d'un centre convectif (phase active) accompagné de la convergence des anomalies du vent zonal de bas niveau et de la divergence de niveau supérieur, et de zones de convection faible (phases supprimées). Trois périodes de l'activité MJO sur l'océan Indien et le continent maritime ont été choisies : 6-14 avril 2009, 23-30 novembre 2011 et 9-28 février 2013. Les simulations avec et sans paramétrisation de la convection ont été réalisées pour un grand domaine avec le modèle atmosphérique Méso-NH. Il a été obtenu que les simulations avec convection paramétrée n'étaient pas capables de reproduire un signal MJO. Pour 2009 et 2011, lorsque le couplage entre la convection et la circulation de grande échelle était fort, les simulations avec convection explicite ont montré une propagation visible de la MJO, ce qui n'a pas été le cas pour 2013. Pour 2011, les processus contribuant à la suppression de la convection ont été étudiés avec une analyse isentropique pour séparer les masses d'air ascendantes ayant une température potentielle équivalente élevée des masses d'air subsidentes ayant une température potentielle équivalente faible. Trois circulations de grande échelle ont été trouvées : une circulation troposphérique, une circulation de percées nuageuses dans la couche de tropopause tropicale, et une circulation de masses d'air à faible température potentielle équivalente dans la basse troposphère. Cette dernière correspond aux intrusions d'air sec de grande échelle des zones subtropicales dans la bande équatoriale, trouvées principalement pendant la phase supprimée de la MJO sur l'océan Indien. / The Madden-Julian Oscillation (MJO) is the dominant component of the intraseasonal variability in the tropical atmosphere, propagating eastward in the equatorial band. It consists of a convective center (active phase) accompanied by the low-level zonal wind anomaly convergence and the upper-level zonal wind anomaly divergence, and zones of weak convection (suppressed phases). Three time periods of the MJO activity over the Indian Ocean and the Maritime Continent were chosen: 6-14 April 2009, 23-30 November 2011, and 9-28 February 2013. The simulations with and without convective parameterizations were performed for a large domain with the atmospheric model Méso-NH. It was obtained that the simulations with parameterized convection were not able to reproduce an MJO signal. For 2009 and 2011 when the coupling between convection and large-scale circulation was strong, the convection-permitting simulations showed a visible MJO propagation, which was not the case for 2013. For the 2011 episode, the processes contributing to the suppression of the convection were studied using an isentropic analysis to separate the ascending air masses with high equivalent potential temperature from the subsiding air masses with low equivalent potential temperature. Three large-scale circulations were found: a tropospheric circulation, an overshoot circulation within the tropical tropopause layer, and a circulation of air masses with low equivalent potential temperature in the lower troposphere. The latter corresponds to the large-scale dry air intrusions from the subtropical zones into the equatorial band, mostly found during the suppressed MJO phase over the Indian Ocean.

This study investigates the upper ocean circulation along the west Australian coast, based on recent observations (WOCE ICM6, 1994/96) and numerical output from the 1/6 degree Parallel Ocean Program model (POP11B 1993/97). Particularly, we identify the source regions of the Leeuwin Current, quantify its mean and seasonal variability in terms of volume, heat and salt transports, and examine its heat balance (cooling mechanism). This also leads to further understanding of the regional circulation associated with the Leeuwin Undercurrent, the Eastern Gyral Current and the southeast Indian Subtropical Gyre. The tropical and subtropical sources of the Leeuwin Current are understood from an online numerical particle tracking. Some of the new findings are the Tropical Indian Ocean source of the Leeuwin Current (in addition to the Indonesian Throughflow/Pacific); the Eastern Gyral Current as a recirculation of the South Equatorial Current; the subtropical source of the Leeuwin Current fed by relatively narrow subsurface-intensified eastward jets in the Subtropical Gyre, which are also a major source for the Subtropical Water (salinity maximum) as observed in the Leeuwin Undercurrent along the ICM6 section at 22 degrees S. The ICM6 current meter array reveals a rich vertical current structure near North West Cape (22 degrees S). The coastal part of the Leeuwin Current has dominant synoptic variability and occasionally contains large spikes in its transport time series arising from the passage of tropical cyclones. On the mean, it is weaker and shallower compared to further downstream, and it only transports Tropical Water, of a variable content. The Leeuwin Undercurrent carries Subtropical Water, South Indian Central Water and Antarctic Intermediate Water equatorward between 150/250 to 500/750 m. There is a poleward flow just below the undercurrent which advects a mixed Intermediate Water, partially associated with outflows from the Red Sea and Persian Gulf. Narrow bottom-intensified currents are also observed. The 5-year mean model Leeuwin Current is a year-round poleward flow between 22 degrees S and 34 degrees S. It progressively deepens, from 150 to 300 m depth. Latitudinal variations in its volume transport are a response to lateral inflows/outflows. It has double the transport at 34 degrees S (-2.2 Sv) compared to at 22 degrees S (-1.2 Sv). These model estimates, however, may underestimate the transport of the Leeuwin Current by 50%. Along its path, the current becomes cooler (6 degrees C), saltier (0.6 psu) and denser (2 kg m -3). At seasonal scales, a stronger poleward flow in May-June advects the warmest and freshest waters along the west Australian coast. This advection is apparently spun up by the arrival of a poleward Kelvin wave in April, and reinforced by a minimum in the equatorward wind stress during July. In the model heat balance, the Leeuwin Current is significantly cooled by the eddy heat flux divergence (4 degrees C out of 6 degrees C), associated with mechanisms operating at submonthly time scales. However, exactly which mechanisms it is not yet clear. Air-sea fluxes only account for ~30% of the cooling and seasonal rectification is negligible. The eddy heat divergence, originating over a narrow region along the outer edge of the Leeuwin Current, is responsible for a considerable warming of a vast area of the adjacent ocean interior, which is then associated with strong heat losses to the atmosphere. The model westward eddy heat flux estimates are considerably larger than those associated with long lived warm core eddies detaching from the Leeuwin Current and moving offshore. This suggests that these mesoscale features are not the main mechanism responsible for the cooling of the Leeuwin Current. We suspect instead that short lived warm core eddies might play an important role.

Glass beads comprise the most frequently found evidence of trade between southern Africa and the greater Indian Oceanbetween the 7th and 16th centuries AD.  In this thesis beads recovered from southern African archaeological sites are organized into series, based on morphology and chemical composition determined by LA-ICP-MS analysis.  The results are used to interpret the trade patterns and partners that linked eastern Africa to the rest of the Indian Ocean world, as well as interconnections between southern Africa andEast Africa.   Comprehensive reports on bead assemblages from several archaeological sites are presented, including: Mapungubwe, K2 and Schroda in the Shashe-Limpopo Basin; Chibuene in southern Mozambique; Hlamba Mlonga in eastern Zimbabwe; Sibudu Cave in KwaZulu-Natal, Kaole Ruins in Tanzania and Mahilaka in northwest Madagascar.  The conclusions reached show that trade relationships and socio-political development in the south were different from those on the East Coast and that changes in bead series in the south demonstrate it was fully integrated into the cycles of the Eurasian and African world-system.

The most important component of the climate system over the Indian Ocean region is the southwest monsoon, which dictates the life and economy of billions of people in the tropics. Being a phenomena that involves interaction between atmosphere, ocean and land, the southwest monsoon is strongly influenced by upper ocean, primarily through warm sea surface temperature (SST). This is particularly true about the southeastern Arabian Sea (SEAS) and the onset of southwest monsoon over the peninsular India. A localized patch of warm water, known as the Arabian Sea mini warm pool (ASMWP), forms in the SEAS during February–March. It remain as the warmest spot in the northern Indian Ocean till early April. A large region, surrounding the SEAS, attains SST exceeding 30°C during April–May, with often the ASMWP as its core. The ASMWP is believed to have a critical impact on the air-sea interaction during the onset phase of southwest monsoon and on the formation of the onset vortex, during late May or early June. This thesis addresses the formation mechanisms of ASMWP, using a high-resolution Ocean General Circulation Model (OGCM) of the Indian Ocean. In addition to the formation of ASMWP, the SEAS is characterized by several features in its hydrography and circulation, which have been invoked in the past to explain the preferential warming of this oceanic region. During November–January, the prevailing surface currents transport low-salinity water from the Bay of Bengal into the SEAS and leads to strong haline stratification in the upper layer and formation of barrier layer (layer between mixed layer and isothermal layer). The vertical distribution of temperature in the SEAS exhibit inversions (higher subsurface temperature than that at surface) during December–February. A high in sea level and anticyclonic eddies develop in the SEAS during December and they propagate westward. These eddies modify the hydrography through downwelling and play an important role in the redistribution of advected low-salinity water within the SEAS. The seasonally reversing coastal and equatorial currents present in and around SEAS also have a major contribution in setting up the hydrography, through the advection and redistribution of cooler low-salinity water. These features make the SEAS a unique oceanographic region. The first hypothesis on the formation of ASMWP, which has been suggested by diagnostic studies, is based on the barrier layer mechanism. The barrier layer, caused by the influx of low-salinity water at surface, is argued to maintain a shallow mixed layer which can warm more efficiently. In addition, presence of barrier layer can prevent mixed layer cooling, by cutting off the interaction of mixed layer with cooler thermocline water below. However, a coupled model study have shown that there is no significant impact on the ASMWP formation from barrier layer, but only a weak warming effect during it mature phase during April. The second hypothesis, which is based on an OGCM study, has suggested that the temperature inversions present within the barrier layer can heat the mixed layer through turbulent entrainment and in turn lead to the formation of ASMWP during February–March. Both hypotheses rule out the possibility of air-sea heat fluxes being the primary reason in its formation. The strong salinity stratification in the SEAS during December–March is central to the hypotheses about formation of the ASMWP. Observational studies have only limited success in assessing the contribution from barrier layer and temperature inversions, as the ASMWP always form in their presence. OGCMs offer a better alternative. However, modelling processes in the northern Indian Ocean, especially that in the SEAS, is a challenging problem. Previous Indian Ocean models have had serious difficulties in simulating the low-salinity water in the Bay of Bengal and its intrusion into the SEAS. The northward advection of low-salinity water in the SEAS, along the west coast of India, is used to be absent in model simulations. Moreover, the coarse resolution inhibited those models from simulating faster surface currents and vigorous eddies as seen in the observations. In this thesis, we use an OGCM of the Indian Ocean, based on the recent version of Modular Ocean Model (MOM4p0), to study the ASMWP. The model has high resolutions in the horizontal (1/4o x 1/4o) and vertical (40 levels, with 5 m spacing in upper 60 m), and has been forced with daily values momentum, heat and freshwater fluxes. The turbulent (latent and sensible) and long wave heat fluxes have been calculated as a function of model SST. The freshwater forcing consists of precipitation, evaporation and river runoff, and there are no surface restoring or flux adjustments. The river runoff has been distributed over several grid points about the river mouth instead of discharging into a singe grid point, which has resulted in remarkable improvements in salinity simulation. The model simulates the Indian Ocean temperature, salinity and circulation remarkably well. The pattern of model temperature distribution and evolution matches very well with that in the observations. Significant improvements have been made in the salinity simulation, including the Bay of Bengal freshwater plume and intrusion of low-salinity water from the bay into the SEAS. The salinity distribution within the SEAS is also well represented in the model. The use of appropriate horizontal friction parameters has resulted in the simulation of realistic currents. The observed features in the SEAS, including the life cycle of the ASMWP, low-salinity water, barrier layer, temperature inversions, eddies and currents are well represented in the model. Present study has unraveled the processes involved in the life cycle of barrier layer and temperature inversions in the SEAS. Presence of low-salinity water is necessary for their formation. Barrier layer develops in the SEAS during November, after the intrusion of low-salinity water from the Bay of Bengal. The barrier layer is thickest during January–February, and it dissipates during March–April. The variations and peak of barrier layer thickness is controlled by variations in isothermal layer depth, which in turn is dominated by the downwelling effects of anticyclonic eddies. The intense solar heating during March–April leads to the formation of shallow isothermal layer and results in the dissipation of barrier layer. Temperature inversions starts developing in the SEAS during December, reaches its peak during January–February and dissipates in the following months. Advection of cooler low-salinity water over warmer salty water and penetrating shortwave radiation is found to cause temperature inversions within the SEAS, whereas winter cooling is also important to the north and south of the SEAS. There is significant variation in the magnitude, depth of occurrence and formation mechanisms of temperature inversions within the SEAS. Analysis of model mixed layer heat budget has shown that the SEAS SST is mainly controlled by atmospheric forcing, including the life cycle of ASMWP. It has also shown that the heating from temperature inversions do not contribute to the formation of ASMWP. In an experiment in which a constant salinity of 35 psu was maintained over the entire model domain, the ASMWP evolved very similar to that in the standard run, suggesting that the salinity effects are not necessary for the formation of ASMWP. Examination of wind field show that the winds over the SEAS during November–February are low due to the blocking of northeasterly winds by Western Ghats. Several process experiments by modifying the wind and turbulent heat fluxforcing fields have shown that these low winds lead to the formation of ASMWP in the SEAS during February–March. The low winds reduce latent heat loss, resulting in net heat gain by the ocean. This helps the SEAS to keep warmer SST while the surrounding region experience intense cooling under the strong dry northeasterly winds. As the winds are weak over the SEAS, the mixed layer is not able to feel the stratification beneath and the mixed layer depth is determined by solar heating, with or without salinity effects. In addition, the weak winds are not able to entrain the temperature inversions present in the barrier layer. The winds are weak during March–April too, and the air-sea heat fluxes dictate the SST evolution during this period. Therefore, during November–April, the SEAS acts as a low wind heat-dominated regime, where the evolution of sea surface temperature is solely determined by atmospheric forcing. We show that, in such regions, the evolution of surface layer temperature is not dependent on the characteristics of subsurface ocean, including the presence of barrier layer and temperature inversions.

Ce mémoire a pour objectif d’analyser la pertinence d’une culture stratégique particulière, celle de l’Inde. Au moins quatre variables culturelles à dimension sécuritaire – l’identité, les valeurs, les normes et les perceptions – permettent d’expliquer la conception de la sécurité et du pouvoir indiens. L’hypothèse avancée dans ce mémoire est la suivante : à cause de l’influence de la culture stratégique indienne, l’océan Indien est perçu par l’élite indienne comme l’endroit où réside la principale menace à la sécurité de l’Inde. En outre, cette perception particulière de la menace permet de mieux comprendre les ambitions maritimes de l’Inde dans l’océan Indien à l’aube du 21e siècle. Afin de confirmer l’hypothèse, nous analysons l’influence de la culture stratégique indienne sur les approches stratégiques privilégiées par les décideurs Indiens au sein de l’océan Indien. Nous concluons, sur la base de l’étude cas, que l’objectif stratégique de New Delhi est de devenir la puissance maritime dominante de l’océan Indien. Le moyen privilégié est la création d’une marine océanique puissante, capable de maintenir en permanence une escadre en patrouille loin de ses bases navales. Sur le plan théorique, les actions indiennes – qui ont surtout un caractère défensif – sont justifiées par une doctrine de non-ingérence des grandes puissances dans les affaires indiennes, doctrine calquée sur la doctrine Monroe. Selon la doctrine indienne, seules les puissances régionales sont à même de préserver la stabilité dans la région de l’océan Indien. Conséquemment, le Gouvernement indien œuvre à réduire l’ingérence des marines de guerre étrangères au sein de l’océan Indien. / This thesis aims to analyze the relevance of a particular strategic culture, that of India. At least four cultural variables, each with a specific security dimension - identity, values, norms and perceptive lens - help us understand the Indian notions of security and power. The main hypothesis put forward in our paper is as follows: because Indian elite are deeply influenced by the prevailing Indian strategic culture, they perceive the Indian Ocean as the place where the main security threat to the country’s security lies. In addition, this particular security perception makes it possible to better understand India’s maritime ambitions in the Indian Ocean at the dawn of the 21st century. To confirm this, we analyze the influence of Indian strategic culture on strategic approaches privileged by Indian decision-makers within the Indian Ocean. We conclude that New Delhi’s strategic objective is to become the dominant maritime power in the Indian Ocean. The means to bring about this end is the creation of a strong blue water navy capable of sustaining a permanent squadron on patrol far from its naval bases. Furthermore, Indian naval activities - which are mainly defensive in nature - are justified by a doctrine of non-interference by major powers in Indian domestic affairs, a doctrine modeled on the Monroe Doctrine. According to the Indian doctrine, only the regional powers are able to preserve stability in the Indian Ocean region. Consequently, the Indian Government works to reduce the presence of foreign naval forces in the Indian Ocean.

Around Sri Lanka and to the south of India sea surface temperatures (SST) are cooler compared to the surrounding region during summer monsoon. This region where SSTs are relatively cooler is known as the cold pool. Owing to its possible impact on monsoon variability, some studies have been carried out to understand the evolution of cold pool SST during this period. These studies suggest, coastal upwelling along southern coast of Sri Lanka and eastward advection of cooler water contributes to the decrease in SST during summer monsoon. However, the processes leading to the formation of cold pool, still, remain unknown. In this study, we have investigated the mechanism responsible for the formation and maintenance of southern Bay of Bengal (BOB) cold pool using high resolution satellite data, model simulations and in-situ observations for the year 2009. Our study reveals formation of cold pool is dominated by atmospheric processes, whereas oceanic processes dominate its maintenance. Cooling of SSTs during premonsoon and onset phase acts as a prerequisites for the formation of cold pool, which are linked to the reduction in Net Heat flux (NHFX) during theses periods. The changes in NHFX during premonsoon and onset phase are dominated by reduction in Short-wave (SW) radiation associated with strong convective activity over cold pool. Convective activity over the cold pool are associated with the northward movement of Maximum Cloud Zone (MCZ) that forms over Equatorial Indian Ocean (EIO) during these periods. SST within the cold pool after the steady increase during February-April months, cools first during premonsoon rain event and then during monsoon onset. Analysis of high resolution satellite data for the period 2003-2009 suggest that, these sequence of events occurs with minor amount of inter-annual variability. Lead-lag correlation also made it clear that SST response in 5 days to the corresponding variation in atmospheric processes. SST within the cold pool shows several intraseasonal cooling events during the summer mon-soon. Considering that rainfall above the cold pool is very low during the summer monsoon, these cooling events occurring within the summer should be necessary for maintaining the cold pool. The seasonal evolution of SST shows that it continues to decrease till the end of the summer monsoon. In-situ data collected during CTCZ field program in 2009, at two time series locations (TSL) and model simulations were used to determine the processes responsible for such cooling events. To estimate the contribution from advection to the observed SST tendency at fixed location, a measurement stratergy called ‘opertaion advection’ was used in this study. This stratergy involves measurement of oceanographic parameters along four edges from TSL directod along North, South, East and West for estimation of horizontal temperature gradients. Our results from SST cooling events captured by CTD at two fixed locations suggests that horizontal advection and entrainment dominate the SST evolution. Model temperature equation evaluated near the TSLs are convinient with the observations and suggest that atmospheric forcing is not responsible for intraseasonal cooling events.

Au cours du XIXe siècle, l’industrialisation de la parfumerie mondiale, et plus particulièrementfrançaise et grassoise, a pour conséquence d’augmenter les besoins en matières premières naturellesmalgré l’invention et la place de plus en plus marquée des molécules de synthèse dans lescompositions parfumées comme aromatiques. Afin de s’approvisionner en plantes à parfum,aromatiques et médicinales (ppam), de nombreux entrepreneurs français et grassois multiplient lesrelations commerciales avec des pays étrangers, comme l’Italie et la Bulgarie. Dans le même temps,l’implantation croissante des parfumeurs en Afrique, en Asie, en Amérique et dans l’Océanie répondà des stratégies diversifiées en fonction des colonies mobilisées : au Maghreb, ils étendent la culturedes ppam méditerranéennes ; en Indochine et en Guyane, ils s’approvisionnent en matières premièresspécifiques comme la badiane ou le bois de rose ; tandis que l’Afrique et l’Océanie font office delaboratoire pour de multiples acclimatations d’espèces méditerranéennes mais surtout tropicales,comme la vanille ou l’ylang-ylang. Parmi ces « colonies laboratoires », les îles de l’Océan Indien,pour lesquelles l’ylang-ylang, le géranium, le giroflier ou la vanille étaient, jusqu’au XIXe siècle,totalement inconnues, deviennent, sous l’impulsion des parfumeurs français et grassois, un desprincipaux centres de production mondiaux. L’objectif de cette thèse est de revenir sur cettetrajectoire singulière, de l’essor des premières fabriques en France jusqu’à la création d’un réseaumondial d’approvisionnement et de questionner les liens et les relations entre les différentes zonesproductrices et la métropole. / During the XIXth century, the beggining of industrialisation of perfumery in the world. Specifically inFrance and in Grasse. Resulted in an augmentation in raw materials in spite of the invention and theincrease of the synthetic molecules in the perfume and aromatic composition. In order to supply itselfin raw materials, many French and Grasse society organise trade relations with foreign countries, likeItaly and Bulgaria. In the same time, the increasing establishment of the perfumers in Africa, Asia,America and Oceania, corresponds in diversified strategies according to the mobilized colonies : inthe Maghreb, they extend the culture of mediterranean raw materials ; in Indo-China and Guyana,they are supplied out of specific raw materials like the star anise or the rose wood ; while Africa andOceania, they serve as a laboratory for multiple acclimatizations of mediterranean raw material andalso tropical species, like vanilla or ylang-ylang. Among these « colonial laboratories », the islandsof the Indian Ocean, for which ylang-ylang, geranium, clove or vanilla, were, until the XIXth century,completely unknown. They became one of the principal world production centers of raw materialsunder the influence of the French and Grasse perfumers. The objective of this thesis is to considerthis singular trajectory, since the rise of the first factories in France until the creation of a worldnetwork of supply. It also questions the links and the relations between the various producing zonesand the Grasse perfumery.

Ce travail de recherche interroge un large corpus romanesque de l’île Maurice, produit en français et en anglais pendant les années 1990 et 2010, sur ses différentes inscriptions de la postcolonialité. Ces dernières années voient un mouvement d’innovation et de rupture esthétique, thématique et poétique parmi une jeune génération d’écrivains francophones tandis qu’un tel dynamisme, à quelques exceptions près, semble moins à l’œuvre dans la littérature mauricienne d’expression anglaise. Alors que les voix novatrices des uns se caractérisent par une écriture de la transgression, de la démystification, de l’anti-tropicalisation ainsi qu’une mise en scène complexe d’interrogations sur des questions identitaires, celles des autres restent confinées dans un certain immobilisme. Le constat d’un champ littéraire clivé à plusieurs égards est inévitable. Une lecture croisée, entre ces différentes scénographies, qui s’articule autour des leitmotivs de la violence et de l’interculturalité permettra d’analyser de façon critique un certain nombre de tendances scripturaires romanesques actuellement en coprésence à Maurice. Selon quelles modalités se fait la représentation et la négociation des espaces-temps insulaires ? Quelles logiques ethnoculturelles et dynamiques idéologiques sous-tendent ces textes ? Comment le roman met-il en scène les facteurs de l’ethnicité, de la classe, du genre ? En d’autres mots, comment pense-t-il – ou refuse de penser – la complexité de la nation multiculturelle ? Notre démarche comparatiste visera à comprendre les spécificités dominantes d’un espace littéraire éclaté et en déséquilibre et de problématiser dans quelle mesure le renouveau poétique offre des réflexions novatrices sur les enjeux identitaires contemporains de la société et la littérature mauriciennes. / This research project explores the different inscriptions of postcolonial identities in an extensive corpus of Mauritian novels written in French and English between 1990 and 2010. Over these last few decades, aesthetic, thematic and poetic innovation can be observed in a young generation of Francophone Mauritian writers, whereas such tendencies are rare among their Anglophone counterparts. While the former can be characterized by their subversive, demystifying and anti-exoticising postures, as well as their complex ways of interrogating issues of identity, the latter rather seem artistically stagnant. The Mauritian literary field clearly reveals itself as unequal as far as quantity and quality are concerned. A postcolonial ‘cross-reading-against-the-grain’ of these different texts, which focuses on leitmotivs of violence and interculturality, allows us to interrogate critically a certain number of literary tendencies currently found in Mauritius. How do the novels negotiate the island’s topographies and temporalities? Which ethno-cultural logics and ideological dynamics can be found underlying these contemporary texts? How do the novels represent complex factors such as ethnicity, class, gender? In other words, how do the Mauritian writers reflect on – or refuse to do so – the complexity of their multicultural nation? This comparative endeavour aims at understanding the dominant characteristics of a very heterogeneous literary field and seeks to analyze to what extent the new aesthetic tendencies offer original perspectives on contemporary issues of identity in Mauritian society as well as its literary production.