Les foraminifères planctoniques vivants (LPF) contribuent à la pompe biologique du carbone océanique en générant des flux de Corg (cytoplasme) et de Cinorg (test calcaire). Dans cette étude, la morphométrie des tests, les abondances et les compositions spécifiques des assemblages de LPF dans l'océan Indien Sud (30°S-60°S, 50°E-80°E), ont été caractérisées à partir de la collecte par filet à plancton stratifié (Multinet) sur 19 stations échantillonnées pendant trois étés consécutifs (2012- 2014). En démontrant l'efficacité d'échantillonnage du Continuous Plankton Recorder pour spatialiser les données observées en 19 stations, l’étude de la dynamique de population des LPF montre l'effet de la position des fronts sur la production des LPF. Pour mieux contraindre l'impact des LPF dans la pompe biologique du carbone des hautes latitudes, la biomasse protéique et la masse calcique de plus de 2000 foraminifères ont été mesurées. Les différences de biomasse protéique et de poids normalisé par la taille entre années, espèces et masses d'eau suggèrent que les paramètres environnementaux affectent la production de Corg et de Cinorg des LPF. Le rôle des LPF sur la pompe biologique de carbone marin dépend des conditions hydrologiques et trophiques du milieu. Le rapport Corg/Cinorg est très différent selon les espèces considérées. L'applicabilité des tests de foraminifères planctoniques comme proxy de paléopompe du carbone dans les hautes latitudes dépendrait donc de l'effet exercé par les variations des conditions écologiques, et de la composition de l’assemblage. Cette étude propose une première estimation des budgets Corg et Cinorg produits par les LPF dans l’Océan Indien Austral. / Planktonic foraminifera contribute to the marine biological carbon pump by generating organic (cytoplasm) and inorganic (shell) carbon fluxes. In this study, we characterized LPF total abundances, assemblages and test morphometry (minimum diameter) along 19 stations sampled by stratified plankton net (Multinet), during three consecutive austral summers (2012-2014) in the Southern Indian Ocean (30°S-60°S, 50°E-80°E). By demonstrating the efficiency of CPR for LPF sampling, we analysed population dynamic between 19 multinet sampling stations, showing the effect of frontal position on LPF production. To better constrain the impact of those organisms in the biological carbon pump at high latitudes, we have quantified the individual protein-biomass and test calcite mass of more than 2000 LPF. Differences in size-normalized protein-biomass and in size-normalized weight between years, species, and water bodies suggest that environmental parameters affect the production of planktonic foraminifera organic and inorganic carbon to varying degrees. Consequently, planktonic foraminifera are assumed to affect the biological carbon pump, depending on ecological conditions and biological prerequisites. The applicability of planktonic foraminifera tests as proxy of the past biological carbon pump in high latitudes would hence critically depend on the effect exerted by changing in ecological conditions, and the presence of different species. This study proposes a first estimation of planktonic foraminifera Corg and Cinorg standing stock and fluxes in the Southern Indian Ocean.

Collecting sea cucumbers to supply the high value Chinese dried seafood market is a livelihood activity available to many people in the Western Indian Ocean (WIO), making it an important part of local economies. These fisheries are generally not successfully managed and tropical sea cucumber fisheries show continuing signs of decline. This thesis takes a social-ecological systems approach to guide better management of sea cucumber fisheries and aquaculture in the WIO. Papers 1 and 2 analyse the fishery situation in Zanzibar and find that in the absence of effective management institutions and income alternatives among fishers, leading to dependence, there are unsustainable expanding processes. Paper 3 compares the unmanaged fishery in Zanzibar to the highly controlled situation in Mayotte. In Mayotte, a protection effect is evident and the commercial value of stocks is significantly higher than in Zanzibar. The analysis of the situation in Mayotte demonstrates the importance of matching the fishery – management temporal scales through prepared and adaptive management to avoid processes that reinforce unsustainable expansion. Paper 4 analyses sea cucumber community spatial distribution patterns at a coastal seascape-scale in Mayotte establishing baseline patterns of habitat utilization and abundance, which can be used as reference in management. Paper 5 reviews the potential for sea cucumber aquaculture in the WIO. The review illustrates that this activity, which is currently gaining momentum, does so based on inflated promises and with significant social-ecological risks. Emphasis for improvements is, in this thesis, placed on the importance of prepared and adaptive institutions to govern and control expanding processes of the fishery. These institutional features may be achieved by increasing the level of knowledge and participation in governance and by integration of sea cucumber resources management into higher-level policy initiatives. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

The aim of this study was to identify the algal genera found in the different freshwater bodies on Marion Island, to relate the presence or absence of the genera to the chemistry of the water bodies and to group the genera according to their limno-chemical preferences. The Island's freshwater algal genera were also compared with genera found on other Southern Ocean islands. The major factors influencing the chemical composition of the freshwaters of the island are the surrounding ocean and the manuring of seals and seabirds. The Western and Southern lakelets and wallows had higher mean conductivity values than most of the other water bodies. Eastern Inland lakelets, crater lakes and glacial lakes had low ion and nutrient concentrations, since they are mainly situated inland, away from bird or seal colonies. The chemical composition of wallows was influenced by manuring of seals and seabirds. The freshwaters are acidic and lakelets tend to be more acidic than glacial lakes. The lentic waters were more acidic than the stream. In total, 106 genera, mainly belonging to Chlorophyta (60 genera; 56% of total) and Cyanophyta (29 genera; 27% of total), were found in the freshwaters on the island. Other algal divisions found were Chrysophyta (7 genera), Euglenophyta (4 genera), Pyrrophyta (2 genera) and Xanthophyta (4 genera). Mean number of genera per sample ranged from 8 (in wallows) to 16 (in Eastern Inland lakelets). Filamentous algae were present in all the samples. Abundant green algae were Cosmarium, Klebsormidium, Mougeotia and Oedogonium. The most common cyanobacteria were Lyngbya and Chroococcus. The filamentous yellow-green alga, Tribonema, was also common. There were distinct differences in the algal composition between the southern, western and northern lakelets and the lakelets on the eastern side of the island. Sixty percent of the algal genera were present in waters with low conductivity values. Trichodesmium, Sphaerocystis and Tolypothrix occurred in freshwater bodies with higher conductivity values. Variance analysis showed that 87 of the 106 genera were less likely to occur in nitrogen and phosphate containing waters. Chlamydomonas, Prasiola, Spirogyra Trachelomonas, Tribonema, Ulothrix and Xanthidium were among the genera commonly found in nitrogen and phosphate containing waters. Diversity (number of genera per sample) was negatively correlated with conductivity, PO4-P, NH4-N and NO3-N. Diversity declined significantly with increasing salinity and eutrophication. Genera likely to occur in acidic waters include Binuclearia, Chlamydomonas, Chroococcus, Cosmarium, Klebsormidium, Microspora, Oedogonium, Oocystis, Prasiola, Scenedesmus, Staurastrum, Stigeoclonium, Tetrastrum, Ulothrix, Lyngbya, Synura and Tribonema. Marion Island’s algal flora shows a high affinity with that of Îles Kerguelen and Crozet, both located in the same biogeographical province (South Indian Ocean Province) of the sub-Antarctic than Marion Island, and a lesser affinity with islands in other sub-Antarctic provinces. Algal genera were grouped according to their limno-chemistry preferences. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.

The aim of this study was to identify the algal genera found in the different freshwater bodies on Marion Island, to relate the presence or absence of the genera to the chemistry of the water bodies and to group the genera according to their limno-chemical preferences. The Island's freshwater algal genera were also compared with genera found on other Southern Ocean islands. The major factors influencing the chemical composition of the freshwaters of the island are the surrounding ocean and the manuring of seals and seabirds. The Western and Southern lakelets and wallows had higher mean conductivity values than most of the other water bodies. Eastern Inland lakelets, crater lakes and glacial lakes had low ion and nutrient concentrations, since they are mainly situated inland, away from bird or seal colonies. The chemical composition of wallows was influenced by manuring of seals and seabirds. The freshwaters are acidic and lakelets tend to be more acidic than glacial lakes. The lentic waters were more acidic than the stream. In total, 106 genera, mainly belonging to Chlorophyta (60 genera; 56% of total) and Cyanophyta (29 genera; 27% of total), were found in the freshwaters on the island. Other algal divisions found were Chrysophyta (7 genera), Euglenophyta (4 genera), Pyrrophyta (2 genera) and Xanthophyta (4 genera). Mean number of genera per sample ranged from 8 (in wallows) to 16 (in Eastern Inland lakelets). Filamentous algae were present in all the samples. Abundant green algae were Cosmarium, Klebsormidium, Mougeotia and Oedogonium. The most common cyanobacteria were Lyngbya and Chroococcus. The filamentous yellow-green alga, Tribonema, was also common. There were distinct differences in the algal composition between the southern, western and northern lakelets and the lakelets on the eastern side of the island. Sixty percent of the algal genera were present in waters with low conductivity values. Trichodesmium, Sphaerocystis and Tolypothrix occurred in freshwater bodies with higher conductivity values. Variance analysis showed that 87 of the 106 genera were less likely to occur in nitrogen and phosphate containing waters. Chlamydomonas, Prasiola, Spirogyra Trachelomonas, Tribonema, Ulothrix and Xanthidium were among the genera commonly found in nitrogen and phosphate containing waters. Diversity (number of genera per sample) was negatively correlated with conductivity, PO4-P, NH4-N and NO3-N. Diversity declined significantly with increasing salinity and eutrophication. Genera likely to occur in acidic waters include Binuclearia, Chlamydomonas, Chroococcus, Cosmarium, Klebsormidium, Microspora, Oedogonium, Oocystis, Prasiola, Scenedesmus, Staurastrum, Stigeoclonium, Tetrastrum, Ulothrix, Lyngbya, Synura and Tribonema. Marion Island’s algal flora shows a high affinity with that of Îles Kerguelen and Crozet, both located in the same biogeographical province (South Indian Ocean Province) of the sub-Antarctic than Marion Island, and a lesser affinity with islands in other sub-Antarctic provinces. Algal genera were grouped according to their limno-chemistry preferences. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.

Tuna are the major marine fishery in Sri Lanka, and yellowfin tuna (YFT) (Thunnus albacares) and skipjack tuna (SJT) (Katsuwonus pelamis) represent 94% of all tuna caught. The tuna catch in Sri Lanka has increased rapidly over recent years and this is true generally for the Indian Ocean. Tuna are a major animal protein source for 20 million people in Sri Lanka, while marine fisheries provide the main income source for most Sri Lankan coastal communities. While the importance of the fishery will require effective stock management practices to be employed, to date no genetic studies have been undertaken to assess wild stock structure in Sri Lankan waters as a basis for developing effective stock management practices for tuna in the future. This thesis undertook such a genetic analysis of Sri Lankan T. albacares and K. pelamis stocks. Samples of both YFT and SJT were collected over four years (2001 - 2004) from seven fishing grounds around Sri Lanka, and also from the Laccadive and Maldive Islands in the western Indian Ocean. Partial mitochondrial DNA (mtDNA) ATPase 6 and 8 genes and nuclear DNA (nDNA) microsatellite variation were examined for relatively large samples of each species to document genetic diversity within and among sampled sites and hence to infer stock structure and dispersal behaviour. Data for YFT showed significant genetic differentiation for mtDNA only among specific sites and hence provided some evidence for spatial genetic structure. Spatial Analysis of Molecular Variance (SAMOVA) analysis suggests that three geographically meaningful YFT groups are present. Specifically, one group comprising a single site on the Sri Lankan west coast, a second group comprising a single site on the east coast and a third group of remaining sites around Sri Lanka and the Maldive Islands. Patterns of variation at nDNA loci in contrast, indicate extensive contemporary gene flow among all sites and reflect very large population sizes. For SJT, both mtDNA and nDNA data showed high levels of genetic differentiation among all sampling sites and hence evidence for extensive spatial genetic heterogeneity. MtDNA data also indicated temporal variation within sites, among years. As for YFT, three distinct SJT groups were identified with SAMOVA; The Maldive Islands in the western Indian Ocean comprising one site, a second group comprising a single site on the east coast and a third group of remaining sites around Sri Lanka and the Laccadive Islands. The mtDNA data analyses indicated two divergent (M^ = 1.85% ) SJT clades were present among the samples at all sample sites. SJT nDNA results support the inference that multiple 'sub populations' co-exist at all sample sites, albeit in different frequencies. It appears that variation in the relative frequencies of each clade per site accounts for much of the observed genetic differentiation among sites while effective populations remain extremely large. Based on combined data sets for management purposes therefore, there is no strong evidence in these data to indicate that more than a single YFT stock is present in Sri Lankan waters. For SJT however, evidence exists for two divergent clades that are admixed but not apparently interbreeding around Sri Lanka. The identity of spawning grounds of these two clades is currently unknown but is likely to be geographically distant from Sri Lanka. Spawning grounds of the two distinct SJT clades should be identified and conserved.

Este trabalho tem por objetivo investigar a História Política do reino Monomotapa, na África austral, em sua relação com os agentes portugueses e luso-africanos estabelecidos no vale e no planalto do Zambeze no século XVII. A partir da última década do século anterior, sucessivos mutapa solicitaram apoio militar tanto à Coroa ibérica quanto a seus súditos que, instalados em terras africanas, arregimentaram e controlavam poderosos exércitos privados, compostos por homens escravizados. Em 1628, o assassinato de um embaixador português enviado à corte do mutapa Nyambo Kapararidze (c.1623-1629), seguido de um embargo comercial no decorrer do qual muitos comerciantes lusos foram atacados e mortos, precipitou um confronto armado entre portugueses e o Estado shona, que se prolongou até o ano de 1632. No centro deste conflito, uma luta pela sucessão dinástica: de um lado aquele que pode ser considerado o legítimo herdeiro do trono, de acordo com o direito costumeiro, Mhande Mavura; de outro, Nyambo Kapararidze, filho do mutapa anterior, Gatse Rucere, que ocupava o trono desde 1623. Mavura derrotou Kapararidze e, em troca do apoio das forças portuguesas, assinou um tratado diplomático com Filipe III, por cujos termos ele passaria a pagar um tributo anual em ouro ao rei ibérico, franquearia aos portugueses o trânsito, o comércio e a exploração das eventuais minas encontradas em seu território, aceitaria a presença permanente de um capitão português em sua corte e permitiria a construção de igrejas católicas de qualquer ordem em suas terras, entre outras concessões. Na visão de alguns historiadores, a assinatura deste tratado representa a conquista portuguesa do território do planalto. Mavura é considerado o fundador de um período de mutapas marionetes monarcas sem personalidade política que, embora oficialmente mantivessem o título dinástico e controle de um território paulatinamente reduzido, atuariam a serviço 10 dos interesses econômicos e políticos alheios ao reino, até a queda do último mutapa, em 1902. Em 1693, contudo, um ataque aos comerciantes estabelecidos na feira de Dambarare, orquestrado pelo mutapa Nyakunembire (1692-1694), pôs fim às pretensões lusitanas de controle do território do planalto. Objeto do presente trabalho, a sublevação deu início a um curto, porém intenso período de agressões que logrou expulsar definitivamente todos os comerciantes portugueses e luso-africanos estabelecidos nas feiras do planalto. Com base em uma cuidadosa releitura das fontes escritas portuguesas, este trabalho funda-se na hipótese de que a assinatura do Tratado de 1629 não inaugurou um período de mutapas marionetes, uma vez que a Coroa portuguesa nunca logrou estabelecer-se formalmente na região, e que a Revolta de 1693-95 foi uma resposta das sociedades do planalto à desestruturação política e social provocada por agentes lusitanos que, agindo à revelia das autoridades portuguesas, perseguiam interesses privados. / This work aims to investigate the Political History of the Monomotapa kingdom in Southern Africa in its relationship with the Portuguese and Luso-African agents established in the valley and plateau of the Zambezi in the 17th century. From the last decade of the previous century, successive mutapa requested military support both to the Iberian Crown and to its subjects who, settled in African lands, regrouped and controlled powerful private armies, made up by enslaved men. In 1628, the Portuguese ambassador\'s murder sent to the court of the mutapa Nyambo Kapararidze (c.1623-1629), followed by a commercial embargo in the course of which many Portuguese merchants were attacked and killed, precipitated an armed confrontation between the Portuguese and the Shona State, which lasted until the year of 1632. At the centre of this conflict was a struggle for dynastic succession: on the one hand, one who can be considered the \"legitimate\" heir to the throne, according to customary law, Mhande Mavura; on the other, Nyambo Kapararidze, son of the previous mutapa, Gatse Rucere, who occupied the throne from 1623. Mavura defeated Kapararidze and, in exchange for the support of the Portuguese forces, signed a diplomatic treaty with Philip III, under whose terms he would pay an annual gold tribute to the Iberian king, granting the Portuguese the transit, the trade and the exploitation of eventual mines found in its territory, he also would accept the permanent presence of a Portuguese captain in his court and allow the construction of Catholic churches of any order in his lands, among other concessions. In the opinion of some historians, the signature of this treaty represents the Portuguese conquest of the territory of the plateau. Mavura is considered the founder of a period of \'puppets mutapas\' monarchs without 12 political personality who, although they officially maintained the dynastic title and the control of a territory gradually reduced, would act to the service of economic and political interests unrelated to the kingdom, until the fall of the last mutapa, in 1902. In 1693, however, an attack on merchants established at the Dambarare fair, orchestrated by the Nyakunembire mutapa (1692-1694), put an end to the Lusitanian claims to control the plateau territory. Object of the present work, the uprising started a short but intense period of aggression that managed to definitively expel all the Portuguese and Luso-African traders established in the fairs of the plateau. Based on a careful re-reading of Portuguese written sources, this work is based on the hypothesis that the signing of the Treaty of 1629 did not inaugurate a period of \' puppets mutapas\', since the Portuguese Crown was never able to establish itself formally in the region, and that the Revolt of 1693-95 was a response from the plateau societies to the political and social disruption provoked by Lusitanian agents who, acting in the absence of the Portuguese authorities, pursued private interests.

Le roman de Mohamed Toihiri : roman fondateur et représentatif de la littérature comorienne. Son étude nous conduit à affirmer que c’est un roman d’analyse sociologique dans la mesure où il constitue un excellent document sur la vie quotidienne des Comoriens durant près de deux décennies (1975-1992). Mais il serait fort réducteur de le limiter à cela car ce roman ne se contente pas de présenter finement le fonctionnement de la société comorienne, il véhicule aussi une critique socio-politique radicale de celle-ci et de ses gouvernants. Ce roman inscrit son lecteur, de façon très subtile, dans son fonctionnement interne. Ce qui amène le commentateur à étudier cette inscription du lectorat ainsi que la réception de ce même roman qui démontre que si le premier roman de Mohamed Toihiri a été accueilli très froidement du fait de son engagement politique, le deuxième, beaucoup plus conciliant sur le plan politique, a bénéficié d’une réception favorable, voire même élogieuse. / Mohamed Toihiri's novel : a founding and representative novel of the Comorian literature. The analysis confoirms it is a sociological novel to the extent that it is a great novel dealing with the Comorians 'daily life for two centuries (1975-1992). But it would be specific to stop there because this novel not only cleverly shows how the Comorian society works, it is also a radical criticism of this socio-political society and of its government. This novel sbtly includes the reader in its internal functioning. Thus the commentator studied this readers inclusion as well as the novel's reception : while his first novel was given a cold welcom due to its political commitment, his second novel, politically softer, received a positive welcome not to say laudatory.

Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Notre thèse présente une approche sociale et environnementale de l'histoire des cyclones dans la société réunionnaise : il s'agit d'évaluer l'impact d'un événement destructeur, le cyclone, dans la mémoire collective et individuelle, dans l'évolution des sciences, des techniques, des alertes, de la gestion de la crise, de l'organisation des secours et de l'aménagement du territoire. Le cyclone peut donc être un objet d'Histoire à part entière. Parallèlement, notre recherche consiste à comprendre les conséquences des cyclones d'un point de vue géographique et humain. L'impact des cyclones est différent selon le lieu frappé et l'habitat ainsi que de leur évolution dans le temps. Par ailleurs, l'histoire des comportements humains apporte d'autres éléments à l'enquête avancée : la solidarité intègre cette région du monde dans un contexte national et international par l'aide sollicitée auprès de la métropole et d'autres pays. Les autorités et les services compétents entrent en compte pour l'administration de l'île et les choix à faire tant en terme de prévention, que d'information et de mobilisation. Parmi les cyclones marquants du XXème siècle, le cyclone des 26 et 27 janvier 1948 est communément appelé « le cyclone du siècle ». Cependant, le cyclone Jenny (28 février 1962), par ses apports, semble être le point de départ d'un demi-siècle de mutations. Et de fait, une césure dans l'histoire de la société réunionnaise. L'objectif final de notre recherche est de contribuer au progrès d'une prise de conscience collective des cyclones afin de mieux limiter les dégâts humains et matériels lors de leurs passages. / Our thesis presents a social and environmental analysis of cyclones history into Reunion Island society: Our purpose is to estimate the impact of a destructive event, the cyclone, on the collective and individual memory, upon sciences and technology evolution, crisis management, emergency services organisation and area development. Then, cyclone can entirely be an object of History. At the same time, we aim to understand cyclones consequences from a geographical and human point of view. Cyclones impact can be different, depending on the place or housing conditions and the way that they evolve in the time. Moreover, history of human behaviour bring other elements to our enquiry: mutual assistance integrate this world area in a national and international context, with help request to French metropolis and others countries. We must take administration and civil services into account in the island management and in the choices to be made, as far as prevention, information or mobilization are concerned. Among outstanding cyclones of the XXth century, January the 26th and 27th of 1948 cyclonic system is usually considered as “the cyclone of the century”. However, the cyclone “Jenny” (February the 28th of 1962), by its contributions, could be considered as a starting point of a half century of mutations. And then a cut into history of Reunion Island society. The final aim of our research is to contribute to a progress of a collective consciousness of cyclones in order to limit human and material damages.

L’étude des déplacements des baleines à bosse (Megaptera novaeangliae) en relation avec les paramètres environnementaux permet d’apporter des informations précieuses sur leur distribution et leurs préférences d’habitats. Grâce à des données d’observations opportunistes collectées dans le canal de Sainte Marie (Nord-Est de Madagascar) et des données de télémétrie collectées pour cette étude (25 baleines équipées de balises Argos), cette thèse a pour objectif l’étude des déplacements et de l’utilisation de l’habitat des baleines à bosse de Madagascar en fonction du sexe et du statut reproducteur. Des variables physiographiques et océanographiques (mesurées par satelllite) ont été extraites sous chaque position. Un schéma général d’utilisation de l’habitat en période de reproduction a également été proposé à partir de données de télémétrie provenant de différentes zones de reproduction de l’Hémisphère Sud: le Brésil (n=82 individus), l’Australie de l’Ouest (n=26) et l’Australie de l’Est (n=11). Dans le canal de Sainte Marie, nos résultats ont montré une ségrégation temporelle d’un mois avec une première partie de saison dominée par les groupes avec baleineaux et une seconde dominée par les groupes sans baleineaux (Chapitre III). La profondeur influence la distribution des groupes sociaux avec une préférence des couples mère-baleineau pour les plus faibles profondeurs (< 20 m). Le long de la côte de Madagascar, les déplacements localisés des femelles sont associés à des habitats plus profonds et plus éloignés de la côte que ce qui avait été supposé (Chapitre IV). En revanche, les mâles ne semblent pas montrer de préférences d’habitats particuliers bien qu’ils diminuent leur vitesse de nage dans les zones peu profondes. En zone océanique, les individus se déplacent de façon plus erratique dans les eaux les moins profondes, de faible courant ou les plus riches en chlorophylle a. La vitesse du courant de surface ne semble pas être un facteur majeur dans le déplacement des baleines à bosse. Cependant, elles semblent suivre la même direction que celui-ci lorsque ce dernier est fort. Notre étude comparative entres les zones de reproduction a montré que la distribution spatiale varie selon la période de la saison, entre les sites étudiés et selon le sexe (Chapitre V). En début et fin de saison, les mâles se déplacent de manière plus directe et exploitent des zones plus au large que les femelles, notamment celles avec baleineau. Au pic de la saison, les mâles et les femelles effectuent des déplacements plus localisés. La prise en compte des différences dans la variabilité spatio-temporelle des mâles et des femelles en zone de reproduction apparait être une nécessité pour mieux comprendre l’écologie des baleines à bosse et contribuer à la conservation de l’espèce. / Of key importance for the comprehension of humpback whales’ (Megaptera novaeangliae) distribution patterns and habitat use is to quantify how ecological and environmental factors affect the distribution of animals, which requires knowledge on dispersal movements of individuals. Using an opportunistic sightings dataset collected in the Sainte Marie Channel (Northeast of Madagascar) and satellite telemetry data acquired for this study (25 tagged whales), the aim of this thesis was to study the movements and the habitat use of humpback whales in Madagascar during the breeding season, according to sex and reproductive status. Physiographic and oceanographic variables (measured by satellite) were extracted under each position. A general distribution pattern of habitat use during the breeding season was also proposed based on additional humpback whales tracks from others breeding grounds of the Southern Hemisphere: Brazil (n=82 individuals), the Western Australian coast (n=26), and the Eastern Australian coast (n=11). In the Sainte-Marie Channel, groups without calves dominated the first 30 days of the breeding season, followed by an increase in groups with calves (Chapter III). Water depth influenced the distribution of social groups with mother-calf pairs more frequently found in relatively shallow water (0-20 m). Along the coast of Madagascar, over the shelf, females showed localized behavior in deep water and at large distances from shore suggesting that their breeding habitat extends beyond the shallow coastal waters (Chapter IV). Males’ active swimming speed decreased in shallow waters, but we found no influence of environmental parameters on males’ movements. In oceanic habitats, both males and females showed localized behaviors in shallow waters and high surface chlorophyll-a concentrations. The active swimming speed accounts for a large proportion of the whale observed speed while observed direction of tagged whales tending to be closer to the current direction when the current intensity was high. Our comparative study between breeding areas showed that the spatial distribution varies according to the period of the season, between the studied sites, sex and breeding status (Chapter V). Early and late in the season, males moved more directly and in more offshore areas than females, especially females with calves. At the peak of the season, both males and females performed more localized movements than at the other periods. Accounting for differences in the spatio-temporal variability of the distribution of males and females in the breeding grounds seems a necessity to better understand the humpback whales ecology and contribute to the species conservation.