Objective sampling design in a highly heterogeneous landscape - characterizing environmental determinants of malaria vector distribution in French Guiana, in the Amazonian region. Auteur(s) : Roux, Emmanuel Gaborit, Pascal Romaña, Christine A Girod, Romain Dessay, Nadine Dusfour, Isabelle Auteurs secondaires : Espace pour le Développement (ESPACE-DEV) ; Université Montpellier 2 - Sciences et Techniques (UM2) - Université des Antilles et de la Guyane (UAG) - Institut de recherche pour le développement [IRD] - Université de la Réunion Institut Pasteur de la Guyane Française ; Institut Pasteur de la Guyane - Réseau International des Instituts Pasteur Université Paris Descartes/PRES Sorbonne Paris-Cité ; Université Paris Descartes - Paris 5 (UPD5) - PRES Sorbonne Paris Cité Unité d'Entomologie Médicale ; Institut Pasteur de la Guyane This study was sponsored by the General Delegation of French Overseas Regions (Délégation Générale à l'Outre-Mer) within the framework of the project "Bioecology of the vectors of malaria in Cacao, French Guiana: towards assessing the exposure risk and improving the vector control". The study was also supported by OSE-Guyamapá, a cross-border cooperation project funded by the operational Program "PO-Amazonie" of the European Regional Development Fund in French Guiana. Éditeur(s) : HAL CCSD BioMed Central Résumé : International audience BACKGROUND: Sampling design is a key issue when establishing species inventories and characterizing habitats within highly heterogeneous landscapes. Sampling efforts in such environments may be constrained and many field studies only rely on subjective and/or qualitative approaches to design collection strategy. The region of Cacao, in French Guiana, provides an excellent study site to understand the presence and abundance of Anopheles mosquitoes, their species dynamics and the transmission risk of malaria across various environments. We propose an objective methodology to define a stratified sampling design. Following thorough environmental characterization, a factorial analysis of mixed groups allows the data to be reduced and non-collinear principal components to be identified while balancing the influences of the different environmental factors. Such components defined new variables which could then be used in a robust k-means clustering procedure. Then, we identified five clusters that corresponded to our sampling strata and selected sampling sites in each stratum. RESULTS: We validated our method by comparing the species overlap of entomological collections from selected sites and the environmental similarities of the same sites. The Morisita index was significantly correlated (Pearson linear correlation) with environmental similarity based on i) the balanced environmental variable groups considered jointly (p = 0.001) and ii) land cover/use (p-value<0.001). The Jaccard index was significantly correlated with land cover/use-based environmental similarity (p-value = 0.001). CONCLUSIONS: The results validate our sampling approach. Land cover/use maps (based on high spatial resolution satellite images) were shown to be particularly useful when studying the presence, density and diversity of Anopheles mosquitoes at local scales and in very heterogeneous landscapes. BMC Ecology pasteur-00914104 https://hal-riip.archives-ouvertes.fr/pasteur-00914104 https://hal-riip.archives-ouvertes.fr/pasteur-00914104/document DOI : 10.1186/1472-6785-13-45 PUBMED : 24289184 | Partager |
On the evolution of the oceanic component of the IPSL climate models from CMIP3 to CMIP5: A mean state comparison Auteur(s) : Mignot, J. Swingedouw, D. Deshayes, Julie Marti, O. Talandier, Claude Seferian, R. Lengaigne, M. Madec, Éditeur(s) : Elsevier Sci Ltd Résumé : This study analyses the impact on the oceanic mean state of the evolution of the oceanic component (NEMO) of the climate model developed at Institut Pierre Simon Laplace (IPSL-CM), from the version IPSL-CM4, used for third phase of the Coupled Model Intercomparison Project (CMIP3), to IPSL-CM5A, used for CMIP5. Several modifications have been implemented between these two versions, in particular an interactive coupling with a biogeochemical module, a 3-band model for the penetration of the solar radiation, partial steps at the bottom of the ocean and a set of physical parameterisations to improve the representation of the impact of turbulent and tidal mixing. A set of forced and coupled experiments is used to single out the effect of each of these modifications and more generally the evolution of the oceanic component on the IPSL coupled models family. Major improvements are located in the Southern Ocean, where physical parameterisations such as partial steps and tidal mixing reinforce the barotropic transport of water mass, in particular in the Antarctic Circumpolar Current) and ensure a better representation of Antarctic bottom water masses. However, our analysis highlights that modifications, which substantially improve ocean dynamics in forced configuration, can yield or amplify biases in coupled configuration. In particular, the activation of radiative biophysical coupling between biogeochemical cycle and ocean dynamics results in a cooling of the ocean mean state. This illustrates the difficulty to improve and tune coupled climate models, given the large number of degrees of freedom and the potential compensating effects masking some biases. Ocean Modelling (1463-5003) (Elsevier Sci Ltd), 2013-12 , Vol. 72 , P. 167-184 Droits : 2013 The Authors. Published by Elsevier Ltd. All rights reserved. http://archimer.ifremer.fr/doc/00170/28102/26612.pdf DOI:10.1016/j.ocemod.2013.09.001 http://archimer.ifremer.fr/doc/00170/28102/ | Partager |
Numerical study of shear on cohesive granular geomaterials : micro-macro relations, microstructure, and application to the simulation of landslides ; Étude numérique du cisaillement des géomatériaux granulaires cohésifs : passage micro-macro, microstructure, et application à la modélisation de glissements de terrain Auteur(s) : Estrada Mejía, Nicolás Auteurs secondaires : Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Université Montpellier II - Sciences et Techniques du Languedoc Alfredo Taboada(taboada@gm.univ-montp2.fr) Éditeur(s) : HAL CCSD Résumé : The present PhD thesis is devoted to the numerical simulation and analysis of shear on cohesive granular materials. In the framework of the Contact Dynamics method, we developed a model of cohesive bonding, which mimics cohesion by cementation. This model involves three contact strength parameters (a tensile strength, a coefficient of sliding friction, and a coefficient of rolling friction) as well as a local criterion, which controls the creation and the breaking of cohesive bonds. All contacts are cohesive at the beginning of the numerical simulations, and contact rupture leads to an irreversible loss of tensile strength (debonding). We varied systematically the three contact strength parameters and studied their influence on the shear strength, the dilatancy, and the microstructure of the granular media. Our results show that internal friction and macroscopic tensile strength have different origins at the contact scale. We also find that the microstructure of the granular media, when sheared at the steady state (also known as the `critical state"), is strongly affected by the local coefficients of sliding and rolling friction. In particular, the mechanical role of the weak network changes with these two contact parameters, which results from the formation of a new structure of force transmission. On the other hand, we also applied the same numerical simulation method to the simulation of landslides. We developed a methodology, which takes into account the initial morphology of the hillslope, the strength of geomaterials, and a triggering factor, integrating in the same model the initiation and propagation phases of the landslide. To illustrate this methodology, we applied it to the simulation of a hypothetical example of avalanche triggered by the progressive rise of a water table. Ce travail de thèse porte sur la modélisation numérique et l'analyse du cisaillement dans les milieux granulaires cohésifs. Dans le cadre de la méthode de la Dynamique des Contacts, nous avons développé un modèle de cohésion qui cherche à imiter la cohésion par cimentation. Ce modèle fait intervenir trois paramètres de résistance au niveau des contacts (une résistance à la traction, un coefficient de frottement de glissement, et un coefficient de frottement de roulement) ainsi qu'un critère de création et de rupture des liens cohésifs. Les contacts sont cohésifs au début des simulations et leur rupture entraîne la perte irréversible de la résistance à la traction. Nous avons fait varier les trois paramètres microscopiques et nous avons étudié leur influence dans la résistance au cisaillement, la dilatance, et la microstructure du milieu. Nos résultats montrent que le frottement interne et l'adhésion macroscopiques ont des origines microscopiques différentes. Nous observons aussi que la microstructure du milieu cisaillé à l'état stationnaire (aussi connu comme ``l'état critique") est fortement affectée par l'angle de frottement et la résistance au roulement au niveau des contacts. En particulier, le rôle mécanique du réseau faible change avec ces deux paramètres microscopiques, ce qui résulte de la formation d'une nouvelle structure de transmission de forces. D'autre part, nous avons appliqué cette méthode de simulation numérique à l'étude d'un processus naturel : les glissements de terrain. Nous avons développé une méthodologie qui tient compte de la morphologie initiale du système, de la résistance des géomatériaux, et d'un mécanisme de déclanchement, ce qui permet d'intégrer dans le même modèle les phases d'initiation et de propagation du glissement. Pour illustrer cette méthodologie, nous l'avons appliquée à la modélisation d'un exemple hypothétique d'avalanche déclenchée par la montée progressive du niveau d'une nappe d'eau. https://tel.archives-ouvertes.fr/tel-00311303 tel-00311303 https://tel.archives-ouvertes.fr/tel-00311303 https://tel.archives-ouvertes.fr/tel-00311303/document https://tel.archives-ouvertes.fr/tel-00311303/file/these_estrada.pdf | Partager |
Retour sur deux projets de développement en aquaculture outre-mer : leçons pour l’avenir Auteur(s) : Lacroix, Denis Éditeur(s) : EDP Sciences Résumé : Lessons for the future from two development projects in aquaculture in the French overseas territories. Numerous research and development projects have been launched since the seventies in the French overseas territories. Their aim was to foster new activities in agriculture based on local productions for local markets, notably in the French West Indies (FWI). In this paper we analyze two development projects on the rearing of giant freshwater prawn, one in the FWI and the other in French Guyana, over twenty years after their launching. The purpose of these compared studies is twofold: first to try to understand why a set of relevant technical innovations ended in failure 15 years later; second to identify recommendations in terms of methodology in order to diminish risks of mistakes or failure for future projects. To reach this goal we followed two approaches. A first analysis is based on a set of three criteria: social acceptability, legitimacy and time planning. The second analysis, justified by the subjective need for an explanatory tool, is based on the actor-network theory. The results show that beyond the levels of political support and financial investment and support the three key criteria for success are: (i) reactivity of the decision-makers, notably when markets change, (ii) quality of leadership transfer between the launching phase and the stabilized phase, and (iii) capacity of the decision-makers to take into account the concrete consequences of the various scenarios. Regarding this third criterion, our analysis suggests that the scenario of full technical success needs to be explored, notably in terms of economic sustainability. The integration of these two types of analyses into an ex-ante frame should contribute to reducing risks of failure in similar development projects. De nombreux projets d’aquaculture ont été menés depuis les années 1970 dans les territoires et départements français d’outre-mer. L’objectif était de diversifier l’agriculture avec des productions destinées au marché local comme aux Antilles, ou à l’exportation comme en Guyane. L’étude s’intéresse au bilan de deux projets d’élevage de la crevette tropicale d’eau douce aux Antilles et en Guyane, plus de vingt ans après leur lancement. L’objectif est de comprendre comment des innovations technologiques pertinentes ont conduit à deux échecs sur le moyen terme et de tirer des recommandations de méthode afin de réduire les risques d’erreurs ultérieures. Pour cela, deux cadres d’analyse sont mobilisés : le premier s’appuie sur les concepts de temporalité, légitimité et acceptabilité ; le second, motivé par la recherche subjective de cadres explicatifs, emprunte la vision de la théorie de l’acteur-réseau. Les trois déterminants majeurs du succès ou de l’échec se révèlent être la réactivité des responsables face aux problèmes d’adaptation à l’évolution des marchés, la qualité du transfert du leadership lors du passage de la phase de lancement à la phase de croisière et enfin la capacité de prendre en compte dès le départ les conséquences des scénarios d’évolution du projet, y compris la réussite technique. Une capacité d’intégration de ces types d’analyse, dans un cadre ex ante, devrait permettre de réduire les risques d’échec dans des projets de développement similaires à venir. Natures Sciences et Sociétés (1240-1307) (EDP Sciences), 2013-12 , Vol. 21 , N. 4 , P. 400-415 Droits : NSS-Dialogues, EDP Sciences 2014 http://archimer.ifremer.fr/doc/00187/29784/28242.pdf DOI:10.1051/nss/2014004 http://archimer.ifremer.fr/doc/00187/29784/ | Partager |
Comparison of spaceborne measurements of sea surface salinity and colored detrital matter in the Amazon plume Auteur(s) : Fournier, Severine Chapron, Bertrand Salisbury, J. Vandemark, Douglas Reul, Nicolas Éditeur(s) : Amer Geophysical Union Résumé : Large rivers are key hydrologic components in oceanography, particularly regarding air-sea and land-sea exchanges and biogeochemistry. We enter now in a new era of Sea Surface Salinity (SSS) observing system from Space with the recent launches of the ESA Soil Moisture and Ocean Salinity (SMOS) and the NASA Aquarius/Sac-D missions. With these new sensors, we are now in an excellent position to revisit SSS and ocean color investigations in the tropical northwest Atlantic using multi-year remote sensing time series and concurrent in situ observations. The Amazon is the world's largest river in terms of discharge. In its plume, SSS and upper water column optical properties such as the absorption coefficient of colored detrital matter (acdm) are strongly negatively correlated (<-0.7). Local quasi-linear relationships between SSS and acdm are derived for these plume waters over the period of 2010-2013 using new spaceborne SSS and ocean color measurements. Results allow unprecedented spatial and temporal resolution of this coupling. These relationships are then used to estimate SSS in the Amazon plume based on ocean color satellite data. This new product is validated against SMOS and in situ data and compared with previously developed SSS retrieval models. We demonstrate the potential to estimate tropical Atlantic SSS for the extended period from 1998 to 2010, prior to spaceborne SSS data collection. Journal Of Geophysical Research-oceans (0148-0227) (Amer Geophysical Union), 2015-05 , Vol. 120 , N. 5 , P. 3177-3192 Droits : 2015. American Geophysical Union. All Rights Reserved. http://archimer.ifremer.fr/doc/00255/36610/35742.pdf DOI:10.1002/2014JC010109 http://archimer.ifremer.fr/doc/00255/36610/ | Partager Voir aussi Amazon-Orinoco river plume SMOS SSS conservative mixing ocean color salinity satellite oceanography Télécharger |
Analyse économique d'une nouvelle technique d'élevage de crevettes en cages flottantes au Brésil Auteur(s) : Paquotte, Philippe Éditeur(s) : Actes de la 8ème Conférence de l'IIFET (Marrakech, juillet 1996) Résumé : In the framework of French-Brazil co-operation, the French Institute of research for exploitation of the sea (IFREMER), the State of Bahia and the company Littoral Sul Maricultura have developed a new technique for shrimp farming (Penaeus vannamei) using floating cages. After trials carried out during three years, this technique turns out very interesting from several viewpoints. The growth speed and the survival rate are very good, the negative effects on the environmental quality are weak and local fishermen have proved eager to adopt this technique as a part-time activity. In the same time, a technico-economic analysis, using a computerised simulation tool, as well as a market analysis in the State of Bahia have been carried out in order to assess the feasibility of such a project and to help research and development decisions. Despite low first investment and good biological results, the ex-farm production cost of shrimps weighing 15 g is as high as 4,5 US$ per kilo. This price is due to the low productivity of the labour and to the cost of nets which have a short life-time. It is possible to consider this activity as profitable on the market of Salvador de Bahia. Nevertheless, the question is how to face the international competition, which is particularly strong in the case of tropical shrimps. The conditions allowing enterprises to develop a strategy based on product quality and environmentally friendliness are reviewed. [NOT CONTROLLED OCR] Dans le cadre de la coopération Franco-Brésilienne, l'IFREMER, l'Etat de Bahia et la société Littoral Sul Maricultura ont développé une nouvelle technique d'élevage de crevettes pénéides (Penaeus vannamei) en utilisant des cages flottantes. Après trois années de mise au point, cette technique s'est avérée intéressante sur plusieurs aspects. La vitesse de croissance et le taux de survie sont très satisfaisants, les effets négatifs sur la qualité du milieu naturel sont faibles et les pêcheurs locaux ont accueilli favorablement cette nouvelle pratique en complément de leur activité traditionnelle. Parallèlement, une analyse technico-économique utilisant un outil de simulation informatique ainsi qu'une analyse du marché de la crevette dans l'état de Bahia ont été conduites afin d'évaluer la faisabilité d'un tel projet et d'orienter les actions de recherche et développement. En dépit d'investissements initiaux plus faibles que dans les élevages en bassins et de bonnes performances zootechniques, le coût de production de crevettes de 15 g atteint 4,7 US$ par kilo. Dans les conditions de marché de l'Etat de Bahia, la rentabilité d'un projet d'élevage de crevettes en cage serait assurée, mais la faible productivité du travail et le coût de remplacement des filets ne permettent pas d'avoir des coûts de production aussi bas que dans les élevages en bassins. C'est pourquoi la question se pose de la possibilité pour ce type de production innovante d'affronter une concurrence internationale très forte comme dans le cas des crevettes tropicales. En particulier, les conditions dans lesquelles les entreprises peuvent développer une stratégie de compétitivité basée sur la qualité de leurs produits et sur le respect de l'environnement sont analysées. [OCR NON CONTRÔLE] Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/1996/acte-4071.pdf http://archimer.ifremer.fr/doc/00000/4071/ | Partager |
Rapport de mission à la Réunion. Projets « Qualitropic » Auteur(s) : Knockaert, Camille Résumé : Pratiquement inexistante il y a 20 ans, la pêche est devenue un secteur économique porteur d'emplois et créateur de valeur ajoutée, et constitue un enjeu de développement local non négligeable. Les activités de pêche se situent sur les localités suivantes : La Possession, Le Port, St Paul, St Gilles, Etang-Salé, St Leu, St Pierre, Terre-Sainte, Langevin, St Philippe, Ste Rose, St Benoît, Ste Marie, St Denis.
La consommation :
18000 tonnes de produits de la mer consommées par an, représentant plus de 80 millions d' en valeur, soit une moyenne de 4.40 / kg par produit, ce qui correspond à une entrée de gamme de congelés en Grandes et moyennes surfaces (GMS), 90% de la population réunionnaise consommatrice de poissons à hauteur de 19 kg/hab./an contre 25 Kg/hab./an en Métropole et 48 aux Antilles Françaises.
Sur les 19 kg/hab./an de poissons consommés, seuls 750 grammes sont issus de la production de la pêche réunionnaise.
[Extraits] Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/2006/rapport-6491.pdf http://archimer.ifremer.fr/doc/00000/6491/ | Partager |
Territorial dynamics and identity claims of the Wayãpi and Teko indigenous people of the municipality of Camopi (French Guiana). ; Dynamiques territoriales et revendications identitaires des Amérindiens wayãpi et teko de la commune de Camopi (Guyane française). Auteur(s) : Tritsch, Isabelle Auteurs secondaires : Ecologie des forêts de Guyane (ECOFOG) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) - Institut National de la Recherche Agronomique (INRA) - Université des Antilles et de la Guyane (UAG) - AgroParisTech - Centre National de la Recherche Scientifique (CNRS) Université des Antilles-Guyane Bernard Thibaut Éditeur(s) : HAL CCSD Résumé : Indigenous territories comprise extensive areas of tropical forest and hold significant social and conservation value. Today, they are subject to various constraints and opportunities, and face many territorial transformations. These transformations are complex and multifaceted. They involve the adoption of new production and consumption modes, the modification of forms of social organisation and identity and territorial claims. However, the links between these on-going processes are still poorly understood, and make difficult to appreciate the adaptation dynamics of indigenous common natural resources management. This thesis is particularly concerned with the territorial dynamics of the Wayãpi and Teko indigenous people of the municipality of Camopi in French Guiana. It integrates methods that include land use analysis using remotely sensed data, socio-economic and agricultural systems analysis at the household scale, and empirical analysis on the influence of identity claims, kinship networks, and conservation policies. It shows that despite the residential settlement around local towns, the growth of cash income from wage labour and welfare, associated with strong kinship networks, allows the revival of mobility and the diversification of indigenous territorialities. Environmental policies implemented on the territory involve processes of identity and territorial claims and motivate the construction of a collective project of endogenous local development. A comparative approach with the situation of the wayãpi people living in Brazil and evolving in a completely different institutional, socio-economic and environmental context shows similar dynamics. Indigenous peoples of these two sites adopt "multi-local" land use systems, allowing them to extend their territory occupation and taking part of a broader dynamic of territorial and identity affirmation. They articulate forest and local town environments. This multi-local land use system can be interpreted as a new form of environmental governance, which overcomes the access difficulties to natural resources around local towns and ensures their sovereignty over the territory. Les territoires amérindiens couvrent de vastes étendues de forêts tropicales et possèdent une forte valeur sociale et environnementale. Soumis à des contraintes et opportunités variées, ils sont de nos jours le siège de nombreuses transformations territoriales. Ces transformations sont complexes et multiformes. Elles impliquent l'adoption de nouveaux modes de production et de consommation, le réajustement des formes d'organisation sociale et des dynamiques de réaffirmation identitaire et territoriale. Or les liens entre tous ces processus sont encore mal compris, et rendent délicate la compréhension des dynamiques d'adaptation des systèmes amérindiens de gestion des ressources communes. Cette thèse s'intéresse particulièrement aux dynamiques territoriales des Amérindiens wayãpi et teko de la commune de Camopi en Guyane française. Elle intègre des données sur l'occupation du sol obtenues par télédétection, des données socio-économiques et productives à l'échelle des ménages et des données qualitatives sur les processus identitaires, les réseaux de parenté, les politiques de conservation et la gouvernance du territoire. Elle montre que malgré la sédentarisation de l'habitat autour des bourgs locaux, la croissance des revenus monétaires issus des emplois salariés et des aides sociales, combinée avec le maintien de réseaux de parenté et d'entraide, permet une redynamisation des systèmes de mobilité et une diversification des territorialités amérindiennes. De plus, les politiques environnementales mises en place sur le territoire impliquent des processus de territorialisation et de revendications identitaires et motivent la construction collective d'un projet de développement local endogène. Une approche comparative avec la situation des Amérindiens wayãpi vivant au Brésil et évoluant dans un contexte socio-économique, institutionnel et environnemental bien différent montre des dynamiques similaires. Les Amérindiens de ces deux pays adoptent des systèmes d'exploitation du territoire multi-locaux, leur permettant d'étendre leur occupation du territoire et s'inscrivant dans une dynamique de réaffirmation identitaire et territoriale. Ils articulent ainsi les espaces de la forêt et des bourgs. Cette forme d'exploitation multi-locale du territoire peut être interprétée comme une nouvelle forme de gouvernance environnementale, qui leur permet de contourner les difficultés d'accès aux ressources naturelles autour des bourgs et d'affirmer leur souveraineté sur le territoire. https://tel.archives-ouvertes.fr/tel-00831619 tel-00831619 https://tel.archives-ouvertes.fr/tel-00831619 https://tel.archives-ouvertes.fr/tel-00831619/document https://tel.archives-ouvertes.fr/tel-00831619/file/These_TRITSCH_mai2013_vf.pdf | Partager |
Douze ans d'aquaculture tropicale Auteur(s) : AQUACOP Éditeur(s) : Actes de Aquaculture en milieu tropical Résumé : An important part of global aquaculture production comes from countries situated in the tropical "belt". Aquaculture in these countries must undergo significant development in the coming decade. Progress in aquaculture development has been underway for the last ten years. High temperatures lead to rapid and continuous growth allowing for year-round production and utilisation of vast coastal areas with unexploited brackish water. Countries interested by this activity are by and large developing countries and the socio-economic conditions are favourable, with an abundant workforce, high local demand and the need create export markets. L' aquaculture dans les pays de la "ceinture" tropicale représente une part importante de la production globale d'aquaculture dans le monde et doit connaître un développement très significatif dans la décennie à venir. Ce mouvement s'est amorcé dans les dix dernières années. En effet, les températures élevées entraînent des croissances rapides et continues, autorisent des productions toute l'année et permettent de valoriser de vastes étendues littorales d'eau saumâtre inutilisées. Les pays intéressés par cette activité sont en majorité en voie de développement et les conditions socio-économiques sont favorables, car il existe une main d'oeuvre abondante, une forte demande interne et le besoin de créer des marchés à l'exportation. [OCR NON CONTRÔLE] Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/1984/acte-4403.pdf http://archimer.ifremer.fr/doc/00000/4403/ | Partager |
Mapping heatwave health risk at the community level for public health action. Auteur(s) : Buscail, Camille Upegui, Erika Viel, Jean-François Auteurs secondaires : Service de santé publique et d'épidémiologie ; Hôpital Pontchaillou - CHU Pontchaillou [Rennes] Laboratoire Chrono-environnement (LCE) ; Université Bourgogne Franche-Comté (UBFC) - Centre National de la Recherche Scientifique (CNRS) - Université de Franche-Comté (UFC) Institut de recherche, santé, environnement et travail [Rennes] (Irset) ; Université d'Angers (UA) - Université des Antilles et de la Guyane (UAG) - Université de Rennes 1 (UR1) - École des Hautes Études en Santé Publique [EHESP] (EHESP) - Institut National de la Santé et de la Recherche Médicale (INSERM) - Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ) Éditeur(s) : HAL CCSD BioMed Central Résumé : International audience ABSTRACT: BACKGROUND: Climate change poses unprecedented challenges, ranging from global and local policy challenges to personal and social action. Heat-related deaths are largely preventable, but interventions for the most vulnerable populations need improvement. Therefore, the prior identification of high risk areas at the community level is required to better inform planning and prevention. We aimed to demonstrate a simple and flexible conceptual framework relying upon satellite thermal data and other digital data with the goal of easily reproducing this framework in a variety of urban configurations. RESULTS: The study area encompasses Rennes, a medium-sized French city. A Landsat ETM + image (60 m resolution) acquired during a localized heatwave (June 2001) was used to estimate land surface temperature (LST) and derive a hazard index. A land-use regression model was performed to predict the LST. Vulnerability was assessed through census data describing four dimensions (socio-economic status, extreme age, population density and building obsolescence). Then, hazard and vulnerability indices were combined to deliver a heatwave health risk index. The LST patterns were quite heterogeneous, reflecting the land cover mosaic inside the city boundary, with hotspots of elevated temperature mainly observed in the city center. A spatial error regression model was highly predictive of the spatial variation in the LST (R2 = 0.87) and was parsimonious. Three land cover descriptors (NDVI, vegetation and water fractions) were negatively linked with the LST. A sensitivity analysis (based on an image acquired on July 2000) yielded similar results. Southern areas exhibited the most vulnerability, although some pockets of higher vulnerability were observed northeast and west of the city. The heatwave health risk map showed evidence of infra-city spatial clustering, with the highest risks observed in a north--south central band. Another sensitivity analysis gave a very high correlation between 2000 and 2001 risk indices (r = 0.98, p < 10-12). CONCLUSIONS: Building on previous work, we developed a reproducible method that can provide guidance for local planners in developing more efficient climate impact adaptations. We recommend, however, using the health risk index together with hazard and vulnerability indices to implement tailored programs because exposure to heat and vulnerability do not require the same prevention strategies. ISSN: 1476-072X inserm-00762303 http://www.hal.inserm.fr/inserm-00762303 http://www.hal.inserm.fr/inserm-00762303/document http://www.hal.inserm.fr/inserm-00762303/file/1476-072X-11-38.pdf DOI : 10.1186/1476-072X-11-38 | Partager |
Coupling physical and biogeochemical processes in the Rio de la Plata plume Auteur(s) : Huret, Martin Dadou, Isabelle Dumas, Franck Lazure, Pascal Garcon, Véronique Éditeur(s) : Elsevier Résumé : A coupled three-dimensional physical-biogeochemical model was developed in order to simulate the ecological functioning of the Rio de la Plata estuary and plume. The biogeochemical model reproduces the nitrogen cycle between five compartments: dissolved inorganic nitrogen, phytoplankton, zooplankton, detritus and dissolved organic nitrogen. The coupling is tested in seasonal climatological configurations and for the particular year 1999. The circulation is forced with Parana and Uruguay rivers discharges, NCEP wind and tide. The biogeochemical model includes loads of inorganic and organic nitrogen from both rivers. The model reproduces the correct tidal amplitudes in the estuary, as well as the most outstanding features of the observed horizontal and vertical structures of the salinity plume. Simulated surface chlorophyll a concentrations exhibit maximum values all year long seaward of the turbidity front, between the 0.5 and 15 isohalines, in agreement with SeaWiFS images of the area. The model simulates well the low primary production in the light-limited highly turbid tidal river (20 gC/m(2)/yr), the high production area in the frontal zone where it can reach 500 gC/m(2)/yr, and the nutrient-limited production in the outer estuary and inner shelf (300 gC/m(2)/yr), with realistic values in each case. According to the 1999 model simulation, the tidal river is the location of organic nitrogen remineralization with a consequent increase of the inorganic pool. At the entrance of the frontal zone, inorganic nitrogen represents about 75% of the whole nitrogen pool, it is reduced to 50% at its sea end-member. The outer estuary has the same sink role for inorganic nitrogen, suggesting that organic nitrogen is the major form exported to the shelf. Continental Shelf Research (0278-4343) (Elsevier), 2005-03 , Vol. 25 , N. 5-6 , P. 629-653 Droits : 2004 Elsevier Ltd. http://archimer.ifremer.fr/doc/2005/publication-334.pdf DOI:10.1016/j.csr.2004.10.003 http://archimer.ifremer.fr/doc/00000/334/ | Partager Voir aussi Rio de la Plata SeaWiFS Primary production Chlorophyll River plumes Biogeochemical modelling Physical Télécharger |
Tectonic structure, lithology, and hydrothermal signature of the Rainbow massif (Mid-Atlantic Ridge 36°14'N) Auteur(s) : Andreani, Muriel Escartin, Javier Delacour, Adelie Ildefonse, Benoit Godard, Marguerite Dyment, Jerome Fallick, Anthony E. Fouquet, Yves Auteurs secondaires : Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE) ; Centre National de la Recherche Scientifique (CNRS) - Institut national des sciences de l'Univers (INSU - CNRS) - Université Claude Bernard Lyon 1 (UCBL) - École normale supérieure - Lyon (ENS Lyon) Institut de Physique du Globe de Paris (IPGP) ; Institut national des sciences de l'Univers (INSU - CNRS) - IPG PARIS - Université Paris Diderot - Paris 7 (UPD7) - Université de la Réunion (UR) - Centre National de la Recherche Scientifique (CNRS) Laboratoire Magmas et Volcans (LMV) ; Université Blaise Pascal - Clermont-Ferrand 2 (UBP) - Institut national des sciences de l'Univers (INSU - CNRS) - Université Jean Monnet [Saint-Étienne] (UJM) - Centre National de la Recherche Scientifique (CNRS) Manteau et Interfaces ; Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) - Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Scottish Universities Environmental Research Centre, Glasgow IFREMER - Centre de Brest ; Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) Éditeur(s) : HAL CCSD AGU and the Geochemical Society Résumé : International audience Rainbow is a dome-shaped massif at the 36°14′N nontransform offset along the Mid-Atlantic Ridge. It hosts three ultramafic-hosted hydrothermal sites: Rainbow is active and high temperature; Clamstone and Ghost City are fossil and low temperature. The MoMARDREAM cruises (2007, 2008) presented here provided extensive rock sampling throughout the massif that constrains the geological setting of hydrothermal activity. The lithology is heterogeneous with abundant serpentinites surrounding gabbros, troctolites, chromitites, plagiogranites, and basalts. We propose that a W dipping detachment fault, now inactive, uplifted the massif and exhumed these deep-seated rocks. Present-day deformation is accommodated by SSW-NNE faults and fissures, consistent with oblique teleseismic focal mechanisms and stress rotation across the discontinuity. Faults localize fluid flow and control the location of fossil and active hydrothermal fields that appear to be ephemeral and lacking in spatiotemporal progression. Markers of high-temperature hydrothermal activity (∼350°C) are restricted to some samples from the active field while a more diffuse, lower temperature hydrothermal activity (<220°C) is inferred at various locations through anomalously high As, Sb, and Pb contents, attributed to element incorporation in serpentines or microscale-sulfide precipitation. Petrographic and geochemical analyses show that the dominant basement alteration is pervasive peridotite serpentinization at ∼160–260°C, attributed to fluids chemically similar to those venting at Rainbow, and controlled by concomitant alteration of mafic-ultramafic units at depth. Rainbow provides a model for fluid circulation, possibly applicable to hydrothermalism at oceanic detachments elsewhere, where both low-temperature serpentinization and magmatic-driven high-temperature outflow develop contemporaneously, channeled by faults in the footwall and not along the detachment fault. ISSN: 1525-2027 hal-01115281 https://hal.archives-ouvertes.fr/hal-01115281 https://hal.archives-ouvertes.fr/hal-01115281/document https://hal.archives-ouvertes.fr/hal-01115281/file/Andreani_et_al-2014-Geochemistry%2C_Geophysics%2C_Geosystems.pdf DOI : 10.1002/2014GC005269 | Partager |
Surface processes impact on present-day deformation of Pyrenees and Western Alps ; Impact des processus de surface sur la déformation actuelle des Pyrénées et des Alpes Auteur(s) : GENTI, Manon Auteurs secondaires : Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Université de Montpellier Jean Chéry Philippe Vernant Éditeur(s) : HAL CCSD Résumé : When the upper crust below the mountain ranges shows crustal extension with a direction collinear to the convergence direction, it is generally accepted that it is the result of gravitational collapse. However, recent studies challenge this paradigm by showing that erosion induces uplift and extension in the central part of the low convergent mountain ranges. In this study, we investigate the impact of denudation on the seismotectonic regime of mountain ranges.In order to identify a relationship between seismotectonic regime and erosion, the first part of this work presents a compilation of data in the mountain ranges. Based on these observations, a simple kinematic model is proposed to predict the seismotectonic regime of the study ranges.For low convergence rate and moderate mean elevation ranges, this model predicts an extension regime when the denudation rate is 15% higher than the convergence rate.The second part is devoted to the development of thermomechanical 2D finite element models to study the impact of surface processes on the deformation of the Pyrenees. The results show that the isostatic response to erosion reactivates pre-existing structures. The kinematics of an inherited fault plane can be predicted due to the gradient of the horizontal surface velocity profile. Thus, a plane located in the eroded zone is reactivated in normal fault when near the border of the erosion area, this same plane is reactivated in reverse fault. These results suggest that the current deformation in the North Pyrenean Zone could be the result of surface processes.Given the small number of studies quantifying erosion rates in the Pyrenees, the models developed in the second part suffer from high uncertainty. To remedy this, we study the central Pyrenees through a study that combines two types of data : watershed denudation rates from cosmogenic isotopes concentration, and incision rates from sediments buried in the karst. These results are presented in chapter 3. Denudation profiles obtained are consistent with reactivation of a normal fault plane located in the North Zone of the Central Pyrenees.From our study in the Pyrenees, a good correlation appears between the value of the rate of erosion and the glacier occupation. Given that the glaciers where more developed in the Alps, it raises the question of the impact of the late-würmian deglaciation on the present deformation of this range. A numerical model detailing this relationship is presented in the fourth chapter. Theresults show that deglaciation of the western Alps is controlled by the rheological heterogeneity of the crust. Some of our models predict uplift rates consistent with those highlighted by geodesy. Lorsque l’extension de la croûte sous les parties hautes des chaînes de montagnes est colinéaire à la direction de convergence, il est traditionnellement admis que le moteur est l’effondrement gravitaire. Pourtant, des études récentes remettent en cause ce paradigme en montrant que l’érosion induit un soulèvement et de l’extension dans la partie centrale des chaînes de montagne à faible taux de convergence. L’objectif de notre étude est d’étudier l’impact de la dénudation de la topographie sur le régime sismo-tectonique des chaînes de montagnes.La première partie de ce travail présente une compilation de données dans les chaînes de montagnes afin de dégager des relations entre régime sismo-tectonique et érosion. Sur la base de ces observations, un modèle cinématique simple permettant de prévoir le régime de la chaîne est proposé. Ainsi, pour les chaînes à faible taux de convergence et d’élévation moyenne, ce modèleprédit de l’extension lorsque le taux de dénudation est 15% plus élevé que le taux de convergence.La deuxième partie est consacrée au développement d’un modèle thermo-mécanique 2D en éléments finis pour étudier l’impact des processus de surface sur la déformation des Pyrénées.Les résultats montrent que la réponse isostatique à l’érosion permet de réactiver des structurespré-existantes. La cinématique d’un plan de faille hérité peut être prédite grâce au gradient du profil des vitesses de surface horizontales. Ainsi, un plan situé dans la zone d’érosion est réactivé en faille normale alors qu’en bordure de cette zone une faille est réactivée en régime inverse. Ces résultats suggèrent que la déformation actuelle des Pyrénées pourrait être la conséquence d’unprocessus d’érosion.Compte tenu du faible nombre d’études quantifiant les taux d’érosion dans les Pyrénées, les modèles développés dans la deuxième partie souffrent d’une forte incertitude. Pour y remédier, nous avons cherché à les quantifier dans les Pyrénées Centrales grâce à une étude qui combine deux types de données : taux de dénudation des bassins versants à partir des isotopes cosmogéniques, et vitesses d’incision à partir des sédiments piégés dans les karsts. Ces résultats sontprésentés dans la troisième partie. Les profils de dénudation obtenus sont compatibles avec unrejeu en faille normale d’un plan situé dans la Zone Nord Pyrénéenne des Pyrénées Centrales.Notre étude dans les Pyrénées, montre une bonne corrélation entre la valeur du taux d’érosion et la cartographie de l’occupation glaciaire. Les glaciers ayant été plus développés dans les Alpes, cela pose la question de l’impact de la déglaciation tardi-Wurmienne sur la déformation actuelle de cette chaîne. Un modèle numérique détaillant cette relation est présenté dans le quatrième chapitre. Les résultats montrent que la déglaciation des Alpes occidentales est contrôléepar l’hétérogénéité rhéologique de la croute. Certains de nos modèles prédisent des vitesses de surrection compatibles avec celles mises en évidence par la géodésie. https://hal.archives-ouvertes.fr/tel-01262333 tel-01262333 https://hal.archives-ouvertes.fr/tel-01262333 https://hal.archives-ouvertes.fr/tel-01262333/document https://hal.archives-ouvertes.fr/tel-01262333/file/these-Genti-2015-postjury.pdf | Partager |
Young Scientist Contract (CJS)2010 - 2015Genomic divergence in wild tree populations: Methods and cases of study ; Young Scientist Contract (CJS)2010 - 2015Genomic divergence in wild tree populations: Methods and cases of study : Louise Brousseau's Scientific report Auteur(s) : Brousseau, Louise Auteurs secondaires : Ecologie des forêts de Guyane (ECOFOG) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) - Institut National de la Recherche Agronomique (INRA) - Université des Antilles et de la Guyane (UAG) - AgroParisTech - Université de Guyane (UG) - Centre National de la Recherche Scientifique (CNRS) Ecologie et Ecophysiologie Forestières (EEF) ; Institut National de la Recherche Agronomique (INRA) - Université de Lorraine (UL) Unité de Recherches Forestières Méditerranéennes (URFM) ; Institut National de la Recherche Agronomique (INRA) Contrat Jeune Scientifique (CJS) Éditeur(s) : HAL CCSD Résumé : il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : ACTIVITY_REPORT Understanding genomic evolution in wild populations is of particular importance because evolution is a central process in our understanding of populations’ history and their future response to global changes. In addition to fundamental knowledge, the study of populations’ evolution has wide applications such as conservation/restoration genetics or epidemiology. Indeed, genetic diversity is the ‘fuel’ for populations’ evolution and adaptation to new conditions, and estimating the extent and the geographic structure of genetic diversity, as well as identifying the evolutionary forces behind (demography, gene flow, and adaptation) are thus major challenges in the current context of global changes. [br/]A particular attention is currently devoted to the process of genetic divergence in wild populations, with emphases on gene flow, local adaptation, and their interactions. Indeed, adaptation in wild populations is supported in many species by many kinds of experiments based on both quantitative phenotypic traits and molecular data. However, the processes governing populations’ evolution are poorly understood in the tropical rainforest of Amazonia, and the relative influence of neutral and adaptive processes are continuously discussed. [br/]I am a young scientist interested in the process of genomic divergence in wild (tree) populations. I aimed at understanding how evolution structures the genetic diversity and governs molecular divergence in wild populations, with particular emphases on gene flow and local adaptation. During five years as a young scientist, I worked on answering the following questions, focusing on two tree species occupying vulnerable areas: mainly [i]Eperua falcata[/i] in Amazonia and, to a lesser extent, [i]Abies alba[/i] in the Mediterranean area.[br/][u]Scientific questions:[/u][br/]- Which evolutionary drivers are responsible of the structure of genetic diversity in wild populations occupying wide areas? This question was addressed at different geographical scales: from large (regional) to very local (microgeographic) scales. [br/]- What is the relative influence of neutral (gene flow, inbreeding) and adaptive drivers in the process of genetic divergence?[br/]- Is microgeographic adaptation possible in spite of extensive gene flow between populations occupying the extreme boundaries of an ecological gradient? [br/]- What is the extent of natural selection in the (whole) genome of wild populations? [br/][br/]My research work is at the interface between three promising disciplines: Evolutionary genomics (i.e. the study of populations evolution and the evolutionary drivers behind), Bioinformatics (i.e. the treatment of next-generation data), and Bayesian modelling (i.e. the empirical calibration of complex mechanistic model). I intend to take advantage of the recent advances in sequencing and informatic technologies to bring up to date the field of ecological genetics and evolutionary biology, by developing modern research strategies to study the process of genomic divergence in wild populations. https://hal.archives-ouvertes.fr/hal-01204218 hal-01204218 https://hal.archives-ouvertes.fr/hal-01204218 PRODINRA : 286326 | Partager |
Larval dispersal and movement patterns of coral reef fishes, and implications for marine reserve network design Auteur(s) : Green, Alison L. Maypa, Aileen P. Almany, Glenn R. Rhodes, Kevin L. Weeks, Rebecca Abesamis, Rene A. Gleason, Mary G. Mumby, Peter J. Auteurs secondaires : The Nature Conservancy ; The Nature Conservancy ARC Centre of Excellence for Coral Reef Studies (CoralCoE) ; James Cook University (JCU) Coastal Conservation and Education Foundation (CCEF) Laboratoire d'Excellence CORAIL (LabEX CORAIL) ; Institut de Recherche pour le Développement (IRD) - Université des Antilles et de la Guyane (UAG) - École des hautes études en sciences sociales (EHESS) - École pratique des hautes études (EPHE) - Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) - Université de la Réunion (UR) - Université de la Polynésie Française (UPF) - Université de Nouvelle Calédonie - Institut d'écologie et environnement Centre de recherches insulaires et observatoire de l'environnement (CRIOBE) ; Université de Perpignan Via Domitia (UPVD) - École pratique des hautes études (EPHE) - Centre National de la Recherche Scientifique (CNRS) College of Aquaculture, Forestry and Natural Resource Management (CAFNRM) ; University of Hawai'i at Hilo Angelo King Center for Research and Environmental Management ; Silliman University Marine Spatial Ecology Laboratory [Brisbane] (MSEL) ; The University of Queensland [Brisbane] Éditeur(s) : HAL CCSD Wiley Résumé : International audience Well-designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1–0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5–3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3–10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds (e.g. some groupers, emperors, snappers and jacks) or thousands of kilometres (e.g. some sharks and tuna). Larval dispersal distances tend to be <5–15 km, and self-recruitment is common. Synthesising this information allows us, for the first time, to provide species, specific advice on the size, spacing and location of marine reserves in tropical marine ecosystems to maximise benefits for conservation and fisheries management for a range of taxa. We recommend that: (i) marine reserves should be more than twice the size of the home range of focal species (in all directions), thus marine reserves of various sizes will be required depending on which species require protection, how far they move, and if other effective protection is in place outside reserves; (ii) reserve spacing should be <15 km, with smaller reserves spaced more closely; and (iii) marine reserves should include habitats that are critical to the life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and be located to accommodate movement patterns among these. We also provide practical advice for practitioners on how to use this information to design, evaluate and monitor the effectiveness of marine reserve networks within broader ecological, socioeconomic and management contexts. ISSN: 1464-7931 Droits : http://creativecommons.org/licenses/by-nc-nd/ hal-01334353 https://hal-univ-perp.archives-ouvertes.fr/hal-01334353 https://hal-univ-perp.archives-ouvertes.fr/hal-01334353/document https://hal-univ-perp.archives-ouvertes.fr/hal-01334353/file/Green_et_al-2015-Biological_Reviews.pdf DOI : 10.1111/brv.12155 | Partager |
Late Quaternary channel avulsions on the Danube deep-sea fan, Black Sea Auteur(s) : Popescu, Irina Lericolais, Gilles Panin, N Wong, H Droz, Laurence Éditeur(s) : Elsevier Résumé : Analysis of new high-resolution seismic-reflection profiles, chirp profiles and previously published sidescan data, together with piston cores on the Danube Fan provide new insight into the recent sedimentation processes in the deep northwestern Black Sea.The latest channel-levee system on the Danube Fan developed probably during the Neoeuxinian lowstand (oxygene isotope stage 2) in a semi-freshwater basin with a water level about 100 m lower than today. Sediment supplied by the Danube was transported to the deep basin through the Viteaz Canyon, which was directly connected to the leveed channel of this system on the middle slope. Channel avulsion was common in the middle fan, as indicated by four main phases of bifurcation. Each phase developed after the same pattern: breaching of the lower and narrower left levee by turbidity currents, building of a unit of High Amplitude Reflection Packets (HARP) by the unchannelized flow while the former channel was abandoned, followed by initiation of a new meandering leveed channel. The northward migration through successive bifurcations is influenced by the asymmetry between levees, hence by the Coriolis effect. In the lower fan where the levees became too low to maintain a stable pathway for the turbiditic flows, channel migration occurred. Locations of HARPs and channels after bifurcation are controlled by the pre-existing bathymetry. Sedimentary deposits are confined between the high levees of unit 0 (the initial phase of the youngest channel-levee system) to the south, and the steep relief of the Dniepr Fan to the north.The HARPs of the most recent phase of avulsion are the most severely constrained by local topography and form a very narrow elongate structure that is at most half as thick as the previous HARPs. Their distal part is not covered by channel-levee systems and is visible both on sidescan mosaics and on chirp profiles and was sampled in core BLKS 98-20.Sea level controlled fan activity but the evolution of the last channel-levee system with several bifurcations during a single sea level lowstand suggests that the primary control of channel avulsion and sand delivery is probably autocyclic.The presence of important HARP sand bodies in the mud-rich Danube Fan is presumed by analogy with a similar seismic facies on the Amazon Fan and indicated by the sands cored in BLKS98-20. However, only drilling of the HARP units could verify this interpretation. Marine Geology (0025-3227) (Elsevier), 2001-09 , Vol. 179 , N. 1-2 , P. 25-37 Droits : 2001 Elsevier Science B.V. All rights reserved http://archimer.ifremer.fr/doc/2001/publication-474.pdf DOI:10.1016/S0025-3227(01)00197-9 http://archimer.ifremer.fr/doc/00000/474/ | Partager |
Discovery of novel proteins involved in spermatogenesis in the rat ; Découverte de nouvelles protéines impliquées dans la spermatogenèse chez le rat Auteur(s) : Chocu, Sophie Auteurs secondaires : Institut de recherche, santé, environnement et travail [Rennes] (Irset) ; Université d'Angers (UA) - Université des Antilles et de la Guyane (UAG) - Université de Rennes 1 (UR1) - École des Hautes Études en Santé Publique [EHESP] (EHESP) - Institut National de la Santé et de la Recherche Médicale (INSERM) - Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ) Université Rennes 1 Charles Pineau Éditeur(s) : HAL CCSD Résumé : Spermatogenesis in mammals is a complex biological function including cellular processes such as proliferation, meiosis and differentiation, aiming to the production of male gametes in the testis. If the seminiferous epithelium is well described in terms of organization and cellular morphology of cells that compose it, the processes by which undifferentiated diploid germ cells enter meiosis and give haploid cells that undergo many morphological transformations, are not fully decrypted. These processes rely on the coordinated and sequential expression of genes, including specific products for each stage of germ cell development These gene products are essential at each key stage of spermatogenesis. Transcriptomics since the 1990s, and proteomics since the 2000s have contributed to the improved. understanding of these mechanisms. A long term proteomic study aiming at characterizing the proteomes of Sertoli cells and germ cells, and a recent study that characterized and quantified the transcriptome of isolated rat testicular cells at high resolution using de novo sequencing of transcripts (RNA-Seq), have been the basis of my thesis work. The latter study showed the accumulation of long non-Coding RNAs (lncRNAs) and testicular unannotated transcripts (TUTs) at meiotic and post-Meiotic stages of spermatogenesis in the rat. In this context, my thesis work aimed at validating the coding potential of many genes expressed in germ cells using RNA-Seq combined with shotgun proteomics, a so-Called PIT (Proteomics Informed by transcriptomics) approach. In this approach, the protein sequences translated from the transcripts assembled by RNA-Seq in the different testicular cell types are integrated into a custom database of protein sequences used to query mass spectrometry data obtained from proteins of meiotic and post-Meiotic cells. The PIT approach showed that 69 TUTs or lncRNA (corresponding to 44 loci) code for proteins in meiotic cells and post meiotic cells, and we confirmed experimentally the meiotic and post-Meiotic expression for two new transcripts encoding for VAMP9, a protein of the SNARE family, and a new testicular enolase T-ENOL. The post-Meiotic expression of T-ENOL protein was confirmed by immunohistochemistry using a polyclonal antibody raised against the recombinant protein. This approach also allowed us to identify new isoforms of known proteins, specific to each stage of spermatogenesis. Germ cells and Sertoli cells maintain a dialogue which is necessary to the success of spermatogenesis and spermiogenesis. Another part of my work aimed at identifying membrane proteins, in germ cells and residual bodies, that may be involved in the dialogue between Sertoli cells and germ cells, using a ICPL relative quantification proteomic approach. The ICPL analysis enabled us to establish a list of 166 proteins whose expression is differential between pachytene spermatocytes, round spermatids and residual bodies. Their differential expression suggests that these proteins may play a role in spermiogenesis. Thanks to the Gene Ontology annotations, a list of 8 proteins with a putative role in signal transduction, cell recognition or differentiation, thus potentially involved in the dialogue between Sertoli and germ cells was drawn. In addition, I provided a first proteome of rat Sertoli cells, germ cells and residual bodies obtained by shotgun proteomics. La spermatogenèse chez les mammifères est une fonction biologique complexe incluant des processus de prolifération cellulaire, de méiose et de différenciation uniques visant à la production des gamètes mâles au sein du testicule. Si l’épithélium séminifère est bien décrit sur le plan de son organisation et de la morphologie des cellules qui le composent, les processus par lesquels les cellules germinales diploïdes indifférenciées entrent en méiose pour donner ensuite des cellules haploïdes subissant par la suite de nombreuses transformations morphologiques, ne sont pas totalement décryptés. Ils reposent sur l’expression coordonnée et séquentielle de gènes dont les produits spécifiques de chaque stade de développement des cellules germinales sont essentiels aux étapes clés de la spermatogenèse. La transcriptomique depuis les années 1990 et la protéomique depuis les années 2000 ont contribué à l’amélioration de la connaissance de ces mécanismes. Une étude protéomique visant à caractériser par des approches systématiques et différentielles les protéomes des cellules de Sertoli et de la lignée germinale, et d’autre part une étude récente, réalisée dans notre unité, qui a permis de caractériser et de quantifier le transcriptome des cellules testiculaires isolées de rat en utilisant le séquençage de novo des transcrits (RNA-Seq), ont été à la base de mes travaux de thèse. Cette dernière étude a mis en évidence l’accumulation de longs ARNs non codants (lncRNAs) et de transcrits testiculaires non annotés (TUTs) aux stades méiotique et post- méiotique de la spermatogenèse chez le rat. Dans ce contexte, mon travail a consisté à valider le potentiel codant de nombreux gènes exprimés dans les cellules germinales par une approche dite PIT (Proteomics Informed by Transcriptomics) couplant protéomique Shotgun et RNA-Seq. Dans ce type d’approche, les séquences protéiques déduites des transcrits des différents types cellulaires, assemblés par RNA-Seq, sont intégrées dans une base personnalisée de séquences protéiques utilisée pour interroger les données de spectrométrie de masse obtenues à partir de protéines de cellules méiotiques et post-Méiotiques. L’approche PIT a permis de montrer que 69 TUTs ou lncRNA (correspondant à 44 loci) codent pour des protéines dans les cellules méiotiques et post méiotiques. L’expression post-Méiotique de deux nouveaux transcrits, l’un codant pour la protéine VAMP9, une protéine de la famille SNARE, et l’autre pour une nouvelle énolase T-ENOL a pu être confirmée. L’expression post-Méiotique de T-ENOL a été confirmée par immunohistochimie à l’aide d’un anticorps polyclonal produit contre la protéine recombinante. Cette approche nous a également permis d’identifier de nouvelles isoformes de protéines connues spécifiques de chaque stade de la spermatogenèse. Les cellules germinales et les cellules de Sertoli entretiennent le dialogue nécessaire au bon déroulement de la spermatogenèse. Une autre partie de mon travail a consisté à identifier des protéines membranaires des cellules germinales et des corps résiduels, susceptibles d’intervenir dans le dialogue entre les cellules de Sertoli et les cellules germinales, par une approche protéomique de quantification relative ICPL. Cette approche a permis d’établir une liste de 166 protéines différentiellement exprimées entre les spermatocytes pachytène, les spermatides rondes et les corps résiduels, qui sont susceptibles de jouer un rôle dans la spermiogénèse. Grâce aux annotations de le Gene Ontology, j’ai pu établir une liste de 8 protéines ayant un rôle supposé dans la transduction du signal, la reconnaissance cellulaire ou bien la différenciation. Par ailleurs, j’ai pu établir par protéomique Shotgun un premier protéome des cellules de Sertoli, des cellules germinales et des corps résiduels chez le rat. https://tel.archives-ouvertes.fr/tel-01127389 Droits : info:eu-repo/semantics/OpenAccess NNT : 2014REN1S064 tel-01127389 https://tel.archives-ouvertes.fr/tel-01127389 https://tel.archives-ouvertes.fr/tel-01127389/document https://tel.archives-ouvertes.fr/tel-01127389/file/2014REN1S064.pdf | Partager |
Assessment of tropical shrimp aquaculture impact on the environment in tropical countries, using hydrobiology, ecology and remote sensing as helping tools for diagnosis Auteur(s) : Fuchs, Jacques Martin, Jean-louis M. Populus, Jacques Résumé : After a period of rapid development of the sites (an increase in both reared surface area and production), tropical shrimp aquaculture is currently being faced with critical problems due to economical and ecological constraints. In many countries with favourable conditions for shrimp aquaculture such as indonesia or Vietnam, sites are often badly selected and/or over-exploited. This conducts to sorne extent to decreases or collapses in the production due to the difficulty in predicting the maximum production capacity of the sites. Furthermore, it appears that production sustainability depends on many factors among which socio-economy and ecolo gy are of prime importance.
The STD3 project titled « Assessment of tropical shrimp aquaculture impact on the environment in tropical countries using hydrobiology, ecology and remote sensing as helping tools for diagnosis )) was initiated in 1994, with the aim to study the sustainability of marine shrimp aquaculture in tropical areas, main! y Indonesia and Vietnam, through the following tasks: (i) improve site selection and study the impact of aquaculture on marine environments presenting a variable sensitivity to organic sewage, (ii) analyse the socio-economical aspects and profitability of the aquaculture industry and of common resources (iii) use remote sensing and geographical data bases for diagnosis and monitoring of site degradation (iv) reinforce the capacity of Asian
scientists through training.
Severa! aquaculture sites have been investigated in the Lampung region (South Sumatra, Indonesia), the Mekong delta (Vietnam) and on the West coast of New-Caledonia, providing a large range of typical ecosystems encountered in Asia and in the Pacifie, from coralline sites to coastal plains with mangrove and deltaic areas. The study concerned the spatial structure and seasonal influence of these ecosystems, the temporal variation during the course of the project (3 years) and the relation between the ecological structure and farm productions.
Remote sensing provides a synoptic vision over large land expanses. Severa! scenes were processed for landuse mapping using conventional classification techniques. Concerning water quality assessment, a general relation for the Java sea was found between image and field data in terms of total suspended matter. Applying this relation to a new site in Sumatra has provided an initial approach to water type and, together with land use mapping, a preliminary assessment of the suitability of the area to shrimp aquaculture development.
Socio-economic research has been focused on the identification ofneeds for collective action, including public policy, in the perspective of shrimp farming sustainability. The main concern is in the regulation of shrimp farming intensification and extensification at the scale of coastal ecosystemic entities in a common property resource management perspective. The common considered here is coastal water quality. Comparing the local development profiles and the institutional grounds for the design and implementation of collective management rules shows that variables such as land tenure system, farm owner socio-economic profile, social homogeneity or heterogeneity of the farmers are key factors to analyse the potential for sustainability. The defmition of
water quality and the possible means to ensure its collective management are discussed. The main conclusion is that the economie incentives to farming development are strong but there is no significant difference among traditional, semi-intensive and intensive systems in terms of economie efficiency or wealth distribution.
The description of the functioning of the different kinds of ecosystems make it possible to give an advice concerning the positioning of the activity inside the ecosystem, and furthermore to have a reference state in order to determine the impact of the activity on the coastal environnement. This impact can be summarized as an increase in the concentration of total suspended matt€?r, of particulate organic matter and of sulfate reducing bacterias. This organic ma~.er is either issued from rearing activities or from telluric origine, due to mangrove eradication when building the ponds.
An evaluation of the relationship existing between productivity and characteristics of each ecosystem bas been conducted by correlating ecological indicators data (concentration of total suspended matter, particulate organic matter, chlorophyll, percentage of pheopigments in total pigments and cyanobacteria and sulfatereducing bacteria in water and sediments) with the average production of the farms. This comparison lead to the compilation of a scale of observed production integrating the range of these environmental parameters with shrimp production levels, bound to facilitate the positioning of shrimp farming in relation with the confmement leve! of each ecosystem.
Lastly, ali geographie data originated from the various compartments of the study have been geo-referenced and loaded into a geographical information system. This allows to display any query made on spatial variables and their related statistical data, including the ir variations over the last few years and to reveal patterns and phenomena otherwise not obvious. Le programme mis en oeuvre par la DRV (Paris, CREMA-L'Houmeau, DELIAO Brest, COP Tahiti, GIE/RA Nouvelle Calédonie), dans le cadre d'un projet européen STD3 «(Sciences et Technique au Service du Développement», en collaboration avec l'Université de Montpellier II, l'Ecole Nationale d'Agronomie de Rennes, l'ITC (Hollande), l'Institut Océanographique de Nha Trang (Vietnam), le BADC de Jepara et le BPPT de Jakarta (Indonésie), avait pour but la mise au point de méthodes permettant d'améliorer la sélection des sites ainsi que le suivi du développement et de l'impact de l'aquaculture des crevettes Péneides en milieu tropical pour éviter la surexploitation. Quatre axes de recherche ont été défmis : a) identifier la nature et quantifier les rejets de déchets issus de ce type d'aquaculture, b) définir les caractéristiques écologiques des écosystèmes susceptibles d'accueillir l'activité aquacole et suivre leur évolution sous l'influence des rejets, c) déterminer l'influence de la gestion des fermes et des ressources (aspects économiques) sur les performances de productivité, d) déterminer la capacité de la télédétection comme outil de diagnostic d'impact à l'échelle de la région, e) mener un programme de formation d'étudiants et jeunes chercheurs Vietnamiens et Indonésiens. Droits : 1998 Ifremer http://archimer.ifremer.fr/doc/00132/24357/22357.pdf http://archimer.ifremer.fr/doc/00132/24357/ | Partager |
Contexte économique et financier international, national et local Auteur(s) : Para, Georges Année de publication : Loading the player... Éditeur(s) : CEREGMIA : Centre d'Etudes et de Recherche en Economie, Gestion et Modélisation Informatique Appliquée Université des Antilles et de la Guyane Extrait de : "Fiscalité et réforme territoriale" : états généraux des finances locales de la Martinique, les 9 et 10 février 2012. Université des Antilles et de la Guyane Description : Monsieur Georges Para nous présente une thématique intéressante sur le "Contexte économique et financier international, national et local". Un focus particulier sur la Martinique est développé à partir des thèmes suivants : démographie, emploi et chômage, activité et production, revenus et inégalités et disparités territoriales. Siècle(s) traité(s) : 21 Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification Permalien : http://www.manioc.org/fichiers/V12183 V12183 | Partager Voir aussi Economie Enquêtes Chômage Insularité Education Commerce Emploi Démographie Crise financière Crise sociale Martinique France ; Télécharger |
Speciation in the Deep Sea: Multi-Locus Analysis of Divergence and Gene Flow between Two Hybridizing Species of Hydrothermal Vent Mussels Auteur(s) : Faure, Baptiste Jollivet, Didier Tanguy, Arnaud Bonhomme, Francois Bierne, Nicolas Éditeur(s) : Public Library Science Résumé : Background: Reconstructing the history of divergence and gene flow between closely-related organisms has long been a difficult task of evolutionary genetics. Recently, new approaches based on the coalescence theory have been developed to test the existence of gene flow during the process of divergence. The deep sea is a motivating place to apply these new approaches. Differentiation by adaptation can be driven by the heterogeneity of the hydrothermal environment while populations should not have been strongly perturbed by climatic oscillations, the main cause of geographic isolation at the surface. Methodology/Principal Finding: Samples of DNA sequences were obtained for seven nuclear loci and a mitochondrial locus in order to conduct a multi-locus analysis of divergence and gene flow between two closely related and hybridizing species of hydrothermal vent mussels, Bathymodiolus azoricus and B. puteoserpentis. The analysis revealed that (i) the two species have started to diverge approximately 0.760 million years ago, (ii) the B. azoricus population size was 2 to 5 time greater than the B. puteoserpentis and the ancestral population and (iii) gene flow between the two species occurred over the complete species range and was mainly asymmetric, at least for the chromosomal regions studied. Conclusions/Significance: A long history of gene flow has been detected between the two Bathymodiolus species. However, it proved very difficult to conclusively distinguish secondary introgression from ongoing parapatric differentiation. As powerful as coalescence approaches could be, we are left by the fact that natural populations often deviates from standard assumptions of the underlying model. A more direct observation of the history of recombination at one of the seven loci studied suggests an initial period of allopatric differentiation during which recombination was blocked between lineages. Even in the deep sea, geographic isolation may well be a crucial promoter of speciation. Plos One (1932-6203) (Public Library Science), 2009-08 , Vol. 4 , N. 8 , P. 1-15 Droits : 2009 Faure et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://archimer.ifremer.fr/doc/00129/24012/21972.pdf DOI:10.1371/journal.pone.0006485 http://archimer.ifremer.fr/doc/00129/24012/ | Partager |