Éditeur(s) : HAL CCSD Elsevier
Résumé : 00000 ăWOS:000386415300011
International audience
Highly biologically active marine sesquiterpene ilimaquinone was selected for chemical modifications. Its biotransformation was investigated using a combinatorial approach as an original way to screen different strains of microorganisms. Mucor circinelloides ATCC 8541 was able to structurally modify ilimaquinone into three different compounds. A stereospecific epoxidation was observed and compared to chemical epoxidation. A hydroxylation of the decalin ring was also observed as well as an unexpected substitution on the quinone ring by ethanolamine. Compounds were evaluated against several cell lines. (C) 2016 Elsevier Ltd. All rights reserved.
ISSN: 0040-4039

hal-01483185
https://hal.archives-ouvertes.fr/hal-01483185
DOI : 10.1016/j.tetlet.2016.09.075

Éditeur(s) : Public Library Science
Résumé : The European Union and other states are moving towards Ecosystem Based Fisheries Management to balance food production and security with wider ecosystem concerns. Fishing is only one of several sectors operating within the ocean environment, competing for renewable and non-renewable resources that overlap in a limited space. Other sectors include marine mining, energy generation, recreation, transport and conservation. Trade-offs of these competing sectors are already part of the process but attempts to detail how the seas are being utilised have been primarily based on compilations of data on human activity at large spatial scales. Advances including satellite and shipping automatic tracking enable investigation of factors influencing fishers' choice of fishing grounds at spatial scales relevant to decision-making, including the presence or avoidance of activities by other sectors. We analyse the determinants of English and Welsh scallop-dredging fleet behaviour, including competing sectors, operating in the eastern English Channel. Results indicate aggregate mining activity, maritime traffic, increased fishing costs, and the English inshore 6 and French 12 nautical mile limits negatively impact fishers' likelihood of fishing in otherwise suitable areas. Past success, net-benefits and fishing within the 12 NM predispose fishers to use areas. Systematic conservation planning has yet to be widely applied in marine systems, and the dynamics of spatial overlap of fishing with other activities have not been studied at scales relevant to fisher decision-making. This study demonstrates fisher decision-making is indeed affected by the real-time presence of other sectors in an area, and therefore trade-offs which need to be accounted for in marine planning. As marine resource extraction demands intensify, governments will need to take a more proactive approach to resolving these trade-offs, and studies such as this will be required as the evidential foundation for future seascape planning.
Plos One (1932-6203) (Public Library Science), 2015-01-27 , Vol. 10 , N. 1 , P. 1-14

Droits : 2015 Tidd 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/00254/36518/35064.pdf
DOI:10.1371/journal.pone.0116335
http://archimer.ifremer.fr/doc/00254/36518/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Before attaining the mantle wedge, where they trigger partial melting, volatiles released from dehydration reactions in the slab have to migrate across a relatively cold (<750 degrees C), peridotite-layer above the incoming slab. In order to unravel the mechanisms allowing for this initial stage of fluid transport, we performed a detailed field and microstructural study of metamorphic prograde peridotites in the Cerro del Almirez ultramafic massif (Betic Cordillera, Spain), where evidences of one of the most important dehydration reactions in subduction zones, the high-pressure antigorite breakdown (P = 1.6-1.9 GPa and T approximate to 680 degrees C), can be mapped in the field. This reaction led to arborescent growth of centimeter-size olivine and orthopyroxene, producing a chlorite-harzburgite with a spinifex-like texture. Microstructural observations and crystal preferred (CPO) mapping show no evidences of solid-state deformation during the prograde growth of olivine and orthopyroxene at the expenses of antigorite. However, a few tens to a hundred meters away from the reaction front, the metamorphic texture is partially obliterated by grain-size reduction in roughly planar conjugate zones, a few mm to meters wide. Grain size reduction zones (GSRZ) are characterized by (1) sharp contacts with undeformed spinifex-like texture domains, (2) important reduction of the olivine grain size (60-250 mu m), (3) olivine color change from brownish to colorless, (4) decrease in the modal amount of orthopyroxene, and (5) at the mm- to cm-scale, irregular shapes and abrupt terminations. Field and microstructural observations exclude that relative displacement took place across these GSRZ. Changes in modal composition imply reactions with fluids undersaturated in silica. Analysis of olivine crystal-preferred orientations (CPO) in GSRZ shows patterns similar, but more dispersed, than those in neighboring spinifex-like domains. It also reveals mm- to cm-scale discrete domains with rather homogeneous crystallographic orientations suggesting inheritance from the preexisting spinifex-like olivines in the host peridotite. Misorientation angles between neighboring grains in the GSRZ show peaks at similar to 5-10 degrees and similar to 20 degrees, but rotations are not crystallographically controlled. Based on these observations, we rule out the formation of the GSRZ by dynamic recrystallization during dislocation creep and propose that they record brittle deformation (microcraking) of the spinifex-like chlorite-harzburgite, probably induced by hydrofracturing at high pressure and relative low temperature conditions (680-710 degrees C). High-pressure hydrofracturing can, thus, be invoked as an efficient mechanism for fluid flow across the cold top-slab mantle layer, hence allowing the slab-derived fluids to ingress in the wedge.
ISSN: 0012-821X

hal-00534035
https://hal.archives-ouvertes.fr/hal-00534035
DOI : 10.1016/j.epsl.2010.06.029

Résumé : This document presents a survey of the sea-related activities in France, i.e. those of the commercial sector (exploitation of mineral and living resources, manufacturing industries, services) and those of the non-commercial public sector (Navy, State services, education, safety, marine research). A chapter is devoted to the protection of the coastal and marine environment. Each activity of the commercial sector is described by key-figures (turnover, value added, employment); the description of the non-commercial public sector includes data on costs, including personnel costs. In addition to these figures, qualitative information is given on the recent development, present situation and future prospect of each activity. This set of data and information makes it possible for the reader to assess the significance of the sea-related economy and the relative weights of its various components.
Ce document présente un panorama des activités liées à la mer en France, c'est-à-dire celles du secteur marchand (exploitation des ressources minérales et vivantes, industrie manufacturière, services) et celles du secteur public non marchand (Marine nationale, services de l'État, enseignement, sécurité, recherche marine). Un chapitre est consacré à la protection de l'environnement littoral et marin. Chaque activité du secteur marchand est décrite par des chiffres-clés (chiffre d'affaires, valeur ajoutée, emploi); pour le secteur public non marchand, sont fournies des données sur les coûts, notamment les coûts de personnel. Ces indicateurs sont accompagnés d'informations qualitatives sur l'évolution récente, la situation actuelle et les perspectives de chaque activité. Cet ensemble de données permet au lecteur d'apprécier l'importance de l'économie maritime et le poids relatif de ses différentes composantes.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2000/rapport-1346.pdf
http://archimer.ifremer.fr/doc/00000/1346/

Résumé : The purpose of this book is to value the economic significance of marine-related activities in France. Each industrial, or public non-commercial, sector is characterized by key figures relating to annual turnover, value added, employment and budget. These figures are accompanied with qualitative information on the recent development, current situation and future perspectives of the sector in terms of markets, employment and technological progress. Public and private R&D, and the protection of coastal and marine environment are also allowed for. Given the diversity of marine-related activities, this information aims at enabling the reader to assess their importance from a comparative angle.
Le présent ouvrage a pour but d'évaluer l'importance économique des activités liées à la mer en France. Chaque secteur - industriel marchand, public non marchand - est caractérisé par des chiffres-clés portant sur le chiffre d'affaires annuel, la valeur ajoutée, l'emploi, le budget. Ces indicateurs sont accompagnés d'informations qualitatives sur l'évolution récente, la situation actuelle et les perspectives du secteur : marchés, emplois, progrès technique. La R&D publique et privée, ainsi que la protection de l'environnement, sont également prises en compte. Compte tenu de la diversité des activités liées à la mer, ces informations visent à permettre au lecteur d'en apprécier l'importance sous un angle comparatif.

Droits : 1998 IFREMER
http://archimer.ifremer.fr/doc/1999/rapport-1312.pdf
http://archimer.ifremer.fr/doc/00000/1312/

Éditeur(s) : Gauthier-Villars
Résumé : Archaias angulatus is a soritid species found in abundance on littoral intertropical carbonate platforms. In the margino-littoral euryhaline biotopes, wedged in the neighbouring littoral marine environment, lives a distinct but similar form: Androsina lucasi. As the latter cannot migrate by sea or be transported by birds or fish, it cannot have been derived phylogenetically from an ancestral species before colonizing this wedged habitat in space and time. Only the idea of a reiterated phenomenon of speciation induced by the environment from another littoral species (Archaias angulatus) can explain its noticeable ubiquity in margino-littoral biotopes isolated from one another but each in contact with the biotopes favoured by Archaias angulatus. This interpretation is reinforced by morpho-structural, taxinomic, biological and ecological data concerning these two taxa.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 1 , P. 33-41

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00098/20895/18509.pdf
http://archimer.ifremer.fr/doc/00098/20895/

Éditeur(s) : HAL CCSD Editions Paralia CFL
Résumé : Le lido de Villeneuve-lès-Maguelone (Languedoc-Roussillon) est un archétype de littoral microtidal, dominé par la houle, en érosion, et largement affecté par la submersion marine lors des tempêtes. Les observations réalisées dans le cadre du Système d'Observation Littoral - Trait de Côte (SO LTC) concernent l'hydrodynamique et le transport sédimentaire dans l'avant-côte et la lagune. La tache d'observation MAGOBS (Observatoire Aresquiers-Maguelone-Palavas) de cet observatoire regroupe un dispositif instrumental automatisé composé de 30 points d'acquisition en temps réel entre 6 mètres de profondeur et le haut de plage (à terre) ainsi que dans la lagune. Le dispositif est opérationnel depuis mai 2011. Son déploiement a permis de déverrouiller les difficultés techniques liées à la mesure temps réel en zone littorale : choix du type des appareils de mesure, de la technologie embarquée, des cadences d'acquisition, résolution des questions du transfert de la donnée. Le dispositif produit 2 Tera-octets de données par an. Les données sont stockées sur un ensemble de serveurs dédiés. Les données sont mises en ligne sur le site du SO-LTC (www.soltc.org), immédiatement après premiers traitements et qualification. Elles commencent à être utilisées pour des calculs de niveau d'eau à la côte, et dansdes outils de prédiction des vagues et des niveaux à la côte associant mesure et modélisation.
ISSN: 1760-8716

hal-00854410
https://hal.archives-ouvertes.fr/hal-00854410
DOI : 10.5150/jngcgc.2012.064-G

Éditeur(s) : Communication, ICES Conference and Meeting (CM), 2010, Nantes
Résumé : Chlordecone is a very persistent insecticide used in banana plantations of the French West Indies between 1972 and 1993. Chlordecone residues were found in inland water, in agricultural and freshwater products, and in marine organisms. This pollution has become of great concern in 2007. Therefore, a governmental action Plan was launched to better assess the pollution and to improve the consumer’s protection. Within this plan, 1048 samples from 69 different species of marine fishes and crustaceans were collected all around both the Guadeloupe and the Martinique Islands and analyzed. The results confirm the presence of chlordecone in marine organisms, with highly variable concentrations (from the detection limit to 1000 μg.kg-1). In 17.9 % of the samples, concentrations exceeded 20 μg.kg-1, the maximum acceptable level in fish according to the French regulation (Anon, 2008). Two main features of this contamination were characterized. 1) Because of the sedimentation of contaminated suspended soil particles, the sheltered bays are more exposed to chlordecone than the open coast where terrigenous flux are dispersed. 2) Species biology, particularly their lifestyle and diet, appear to influence contamination levels. Thus, the more contaminated species live in relation with sediment or are at high trophic level. These results have directly supported political decisions in order to prevent too high exposure of consumers to chlordecone. Fishing activities in sheltered bays have been forbidden for potentially highly contaminated species like benthic crustaceans and top predators. Further studies are under way to assess the importance of the trophic transport of chlordecone within the foodweb, and to evaluate the historical deposition of this insecticide in sediment and its further bioavailability.

Droits : 2010 ICES/CIEM ; Ifremer
http://archimer.ifremer.fr/doc/00014/12511/9361.pdf
http://archimer.ifremer.fr/doc/00014/12511/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Melting experiments were performed on a silica-rich peridotite composition at 10-17 GPa to determine majoritic garnet-melt partition coefficients (D) for major and trace elements. Our results show that D for many elements, including Na, Sc, Y and rare earth elements (REE), varies significantly with increasing pressure or proportion of majorite component. Lu and Sc become incompatible at 17 GPa, with D decreasing from 1.5 at 10 GPa to 0.9 at 17 GPa. As predicted from lattice strain, log D for isovalent cations entering the large site of majoritic garnet exhibits a near-parabolic dependence on ionic radius. Our data are used to refine a previously published predictive model for garnet-melt partitioning of trivalent cations, which suffered from a lack of calibration in the 10-20 GPa range. Our results suggest that Archean Al-depleted komatiites from Barberton (South Africa) may have been generated by partial melting of dry peridotite at depths between 200 and 400 km. We also speculate that transition zone diamonds from Kankan (Guinea), which contain inclusions of majoritic garnet, may have formed from the partial reduction of CO2-rich magmas that subsequently transported them to the surface. This hypothesis would provide an explanation for the REE patterns of majoritic garnet trapped within these diamonds, including Eu anomalies. Finally, we show that segregation of majoritic garnet-bearing cumulates during crystallisation of a deep Martian magma ocean could lead to a variety of Lu/Hf and Sm/Nd ratios depending on pressure, leading to a range of ε143Nd and ε176Hf isotope signatures for potential mantle sources of Martian rocks.
ISSN: 0024-4937

hal-00767567
https://hal.archives-ouvertes.fr/hal-00767567
DOI : 10.1016/j.lithos.2012.06.013

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Yearly monitoring in one of the most affected coastal zones by the Prestige oil spill, namely Nemiña and O Rostro beaches (NW Spain), has been carried out since 2004. Topographic data of beaches revealed seasonal altimetric changes up to 4 m that would prevent the on shore persistence of oil. However, surficial and subsurficial oil was detected in the intertidal area of both beaches in all campaigns. The hydrocarbon analysis confirmed that this oil corresponded to the Prestige oil, even nine years after the accident. Tar balls were highly biodegraded suggesting that the oil was accumulated on the subtidal sediments for a long time and transported to the coast by the action of waves. The present work provides new evidence of the long term persistence of deep oil spills from wrecks in marine areas where the hydrodynamic conditions play a twofold key role, in determining the exposed coastal area to recurrent contamination and in burying and resurfacing the oil in the intertidal zone.
ISSN: 0304-3894

hal-01071707
https://hal.archives-ouvertes.fr/hal-01071707
DOI : 10.1016/j.jhazmat.2013.01.057

Éditeur(s) : Actes du colloque, April 28-30 1997
Résumé : Due to favourable environmental conditions and political will, marine fish farming has developed recently around the Mediterranean. The Mediterranean area is characterised by a large number of islands which are extremely diversified from geographical, political or socioeconomic point of views. As a matter of fact, it turns out that almost a third of the Mediterranean fish farming production comes from these islands which have proven to offer good conditions for the development of that new activity. The reasons why somany enterprises have been established on islands are very diverse. Taking advantage of good environmental conditions is the most common motivation, since islands are usually less submitted to constraints due to town extension, industry development or intensive agriculture. Moreover, as far as European Union countries are concerned, incentive policy towards ultraperipheral or late development regions has made it possible to attribute specific subsidies to islands for aquaculture in the aim of more employment and wealth. Like any other economic activity, aquaculture has to face some specific constraints due to the insular context. Transport to and from the islands is more expensive and less regular, which has a negative impact on the price competitiveness of the insular products. Local markets are often too small to make it possible for the enterprises to develop first at a domestic level and to take advantage of economies of scale. Thanks to their positive and attractive world-wide image, Mediterranean islands could promote the quality of their products on the basis of geographical origin, of quality of the environment or of specific production processes. Information networks implementation and marketing approach in terms of image are challenges Mediterranean islands have to take up in order to supply the large European seafood market with quality products. [NOT CONTROLLED OCR]
Grâce à de bonnes conditions de milieu et à une volonté politique affirmée, l'élevage des poissons marins s'est développé récemment dans la Méditerranée. Le bassin méditerranéen possède un très grand nombre d'îles qui sont très diverses de par leur caractéristiques géographiques, politiques ou socio-économiques. Près du tiers de la production de poissons marins d'élevage des pays méditerranéens est réalisée dans des îles. Les raisons qui ont incité tant d'entreprises à s'établir sur des îles sont diverses. La motivation principale avancée par les promoteurs de l'aquaculture insulaire méditerranéenne est la qualité de l'environnement des îles et la disponibilité en sites, justifiée par le fait que les îles sont moins soumises à certaines contraintes comme l'extension des villes, le développement de zones industrielles ou l'intensification de l'agriculture. La politique d'aide envers les régions ultra-périphériques ou en retard de développement a permis d'attribuer des subventions spécifiques aux îles pour développer l'aquaculture dans un objectif de création de richesse et d'emploi. Comme toute autre activité économique dans les îles, l'aquaculture doit faire face à des contraintes directement liées à l'insularité. Le transport est plus coûteux et moins régulier, ce qui a un effet négatif sur la compétitivité prix des produits. Les marchés locaux sont souvent trop petits pour permettre aux entreprises de se développer d'abord en interne et de profiter d'économies d'échelle. Une réponse possible à cette contrainte de concurrence internationale pourrait être la promotion des produits sur la base de l'origine géographique,de la qualité de l'environnement ou de procédés de production spécifiques afin de valoriser l'image très positive et la notoriété de ces îles dans le monde entier. Les réseaux dédiés à l'information, à la recherche et au transfert technologique sont des outils nécessaires pour compenser les contraintes dues à la petite taille et à l'isolement dans le but de fournir le vaste marché européen en produits de la mer de qualité. [OCR NON CONTRÔLE]

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1997/acte-4010.pdf
http://archimer.ifremer.fr/doc/00000/4010/

Éditeur(s) : Université de Bucarest - Université de Bretagne occidentale
Résumé : This study is focusing on the architecture and recent sedimentary evolution of the Danube channel, the youngest channel-levee system in the Danube deep-sea fan. The study was conducted as part of the BlaSON French-Romanian Project, and combined high-resolution seismic-reflection profiles and chirp profiles with multibeam bathymetry and piston cores. This data set was acquired in 1998 during a joint survey IFREMER-GeoEcoMar of the north-western Black Sea. Previous seismic and acoustic data were also used. The Danube deep-sea fan is a large passive-margin mud-rich fan. Like the other systems of this type (Amazon fan, Mississippi fan or Indus fan) the Danube fan consists of stacked channel-levee systems intercalated with mass-transport deposits. Seismic and sedimentary facies in the Danube fan are similar to those identified in most of the mud-rich systems. Nevertheless, the Danube fan is distinguished by a specific feature: its development in a freshwater environment. This is due to the peculiar water-level history of the Black Sea controlled by the link to the Mediterranean through the Strait of Bosphorus and the Sea of Marmara. This connexion was successively interrupted (during sea level lowstands) and re-established (when the sea level was rising above the Bosphorus). Temporary absence of marine water influx during lowstands together with large freshwater inputs from the Danube and other major rivers changed the Black Sea into a freshwater lake during times of fan activity. This peculiarity possibly favourised the development of hyperpycnal flow at the Danube mouth and the initiation of turbidity currents in the deep-sea fan. The Danube channel is directly connected to the large shelf-indenting Danube canyon (also known as Viteaz canyon). The Danube canyon is deeply incised into the shelf margin for 26 km landward of the shelfbreak. During lowstands this canyon acted as the most important path for sediment supply to the deep sea in this part of the continental margin. It consists of a main trough with steep flanks, and a meandering thalweg cut into the flat canyon floor, attesting for the development of the canyon by erosion in the entrenched axial thalweg. Sections with specific morphology, orientation and gradient identified along the canyon, are interpreted as phases of landward expansion of the canyon. Internal structure of the canyon shows several erosional surfaces, which indicate that the present morphology of the canyon is the result of its polyphasic evolution. Instability in the zone of the canyon is related to the important sediment supply at the Danube mouth, to the presence of the gas in the surficial sediment, and possibly under a structural control. The upper part of the Danube channel (between the Danube canyon and ~1400 m depth) consists in a single leveed-channel that has undergone significant overbank deposition, as attested by the well-developed levees. The levees are strongly asymmetrical, being higher and wider on the right-hand side looking downstream. This type of asymmetry is rather common in deep-sea fans, and is generally attributed to the Coriolis effect (Menard, 1955). The channel is slightly sinuous, partially filled and incised by an entrenched thalweg, connected to the axial thalweg of the Danube canyon. Detailed seismic investigation inside the channel trough documented several depositional phases within the channel fill, separated by erosional surfaces. These surfaces are associated with distinct terraces identified on the multibeam bathymetry, that can be followed downward along the main trough axis. The valley fill deposits (where not removed by the subsequent erosional event) show an axial HAR (High Amplitude Reflections) seismic facies with lateral lower amplitude continuous reflections consisting in a levee facies, as proved by sampling. This indicates that filling up was associated with flow within the channel, and not with interruption of fan activity. On the middle slope below 1400 m, this single channel bifurcates through repeated avulsions. As a result, several highly meandering channels developed. The onlap relationships between these channels indicate that only one channel was active at a time. Each phase of avulsion resulted in a depositional unit consisting in a basal unchannelized lobe defined as High Amplitude Reflection Packets (HARP, Flood et al., 1991) that underlies a channel-levee system. The deposition of HARPs was associated with the readjustment of the longitudinal profile of the channel after the breaching of a levee, which resulted in remobilization of upslope channel deposits and eroded levees. When this adjustment was complete, erosion ceased and levees began to develop above the HARPs (Pirmez et al., 1997). All the identified phases of avulsion followed the same pattern: (1) breaching of the lower and narrower left levee; (2) building of a unit of High Amplitude Reflector Packets (HARP) basinward of the bifurcation point by the unchannelized flow, while the former channel was abandoned; and (3) initiation of a new meandering leveed channel. The northward migration of the resulting units through repeated bifurcations is influenced by the asymmetry between levees (hence by the Coriolis effect), and confined between the high levees of the initial phase of the Danube channel (to the south) and the steep relief of the Dniepr fan (to the north). Structure of the fan valley fill indicate that the erosional surfaces inside the upper channel could be formed in response of successive avulsions, by the adjustment of the longitudinal profile of the channel following the breaching of a levee wall. Sediments removed by erosion formed the HARP lobes basinward of the avulsion point. When this adjustment was complete, a channel-levee system developed downward of the bifurcation, overlying the HARPs, but also upward of this point, as a confined channel-levee system inside the erosional trough of the fan valley. Fluvial incisions identified on the continental shelf, together with the coastline location during the last active period of the Danube channel, indicated that the paleo-Danube was directed towards the head of the Danube canyon. Paleo-Danube mouth was fairly close (ca. 10 km) to the Danube canyon, supplying sediment to the Danube channel. Furthermore, hyperpycnal flow probably prevailed in the freshwater environment that characterized the Black Sea during times of fan activity. These conditions would have enabled the development of a quasi-continuous river-canyon-deep-sea fan system, ensuring the effective transfer of the sediment between the coastal zone and the deep sea.
Ce travail est consacré à l'étude de l'architecture et de l'évolution sédimentaire récente de l'éventail profond du Danube, en particulier de son dernier système chenal-levée: le chenal du Danube. L'étude a été réalisée dans le cadre du projet de coopération franco-roumaine BlaSON, à partir des données sismiques, bathymétriques-acoustiques et sédimentologiques acquises en 1998 lors d'une campagne en mer Noire réalisée par IFREMER et GeoEcoMar. Des données sismiques et acoustiques antérieures ont été également utilisées. L'éventail profond du Danube s'enserre dans la catégorie des grands éventails vaseux. Comme les autres systèmes de ce genre (tel que les éventails de l'Amazone, du Mississippi ou de l'Indus) il est constitué d'une succession de systèmes chenaux-levées intercalés avec des dépôts de transport en masse. Le fonctionnement de l'éventail était conditionné par la baisse du niveau marin lors des périodes glaciaires. Ses faciès sismiques et sédimentaires s'apparentent aux faciès qui caractérisent la plupart des éventails de ce type. L'éventail du Danube constitue néanmoins un cas particulier parmi les autres systèmes étudiés, du fait de son fonctionnement dans un bassin lacustre. Ceci est dû à la situation spécifique de la mer Noire dont la connexion avec la Méditerranée, par le détroit de Bosphore et la mer de Marmara, a été successivement interrompue (au cours de périodes de bas niveau) et reprise (quand le niveau marin remontait en dépassant le seuil du Bosphore). L'absence de l'apport d'eau salée pendant les périodes glaciaires, associée avec l'augmentation de l'apport fluvial, ont déterminé l'installation d'un milieu d'eau douce dans la mer Noire à chaque fois que la baisse du niveau permettait la reprise du fonctionnement de l'éventail profond. Cette situation particulière aurait favorisé la formation des courants hyperpycnaux à l'embouchure d'un fleuve du débit du Danube qui déversait ses eaux turbides dans un bassin lacustre, et aurait donc influencé l'apparition de courants de turbidité dans l'éventail profond. Le chenal du Danube s'est développé sur la pente continentale en prolongation du canyon du Danube (ou Viteaz) auquel il est directement connecté. Le canyon est incisé de manière significative (26 km) dans la plate-forme continentale. Au cours de bas-niveaux marins il constituait la principale voie de transfert des sédiments terrigènes vers le bassin profond dans cette partie de la marge. Le canyon est constitué par une entaille avec des flancs abrupts et un talweg axial incisé, qui montre l'importance du processus d'érosion du fond pour le développement du canyon. Les segments qui ont été identifiés le long du canyon, avec des morphologies, des orientations et des pentes spécifiques, sont interprétés comme des phases d'avancement du canyon vers la côte. Plusieurs incisions sont visibles dans la structure interne du canyon et témoignent que la morphologie actuelle du canyon est le résultat de son évolution polyphasée. L'instabilité de la zone du canyon est en relation avec les apports sédimentaires importants à l'embouchure du Danube, avec la présence du gaz dans les sédiments superficiels, et possiblement sous un contrôle structural. Sur la pente supérieure (entre le canyon du Danube et environ 1400 m de profondeur) le chenal du Danube présente des levées bien développées et fortement asymétriques, avec la levée droite plus haute et plus large que la levée gauche. Ce type d'asymétrie, fréquemment décrit dans les éventails profonds est généralement attribué à l'effet Coriolis (Menard, 1955). Le chenal est légèrement sinueux, partiellement comblé et incisé par un talweg axial qui représente la continuation sur la pente du talweg incisé dans le canyon du Danube. L'analyse sismique détaillée du remplissage de la vallée montre plusieurs phases de dépôt, séparées par des discontinuités érosives. Ces surfaces d'érosion correspondent à des terrasses emboîtées, relativement parallèles le long de la vallée, visibles dans la bathymétrie. Les dépôts qui constituent le remplissage du chenal présentent un faciès sismique de type HAR (High Amplitude Reflections) dans l'axe du chenal, partiellement (ou parfois totalement) enlevé par les phases d'érosion subséquentes, qui continue latéralement avec des réflexions litées correspondant à un faciès sédimentaire de levée. Le remplissage de la vallée a été donc associé avec des écoulements dans le chenal, et non pas avec l'interruption de son fonctionnement. Sur la pente inférieure, le chenal unique bifurque plusieurs fois par avulsion et forme de nouveaux systèmes chenaux-levées méandriformes. Ces systèmes se succèdent verticalement en onlap, ce qui montre qu'un seul chenal a été actif à la fois. Chaque phase d'avulsion a eu comme résultat la mise en place d'une unité constituée par un lobe défini comme "High Amplitude Reflection Packets" (HARP, Flood et al., 1991) à la base, et un système chenal-levée au sommet. Le dépôt d'un lobe HARP est associé avec de l'érosion dans le chenal en amont du point d'avulsion pour l'ajustement de son profil après la rupture de la levée. Quand le chenal a retrouvé son profil d'équilibre, l'érosion a cessé et des levées ont commencé à se développer au-dessus des HARPs (Pirmez et al., 1997). Toutes les phases d'avulsion se sont développées d'après le même modèle: (1) la rupture de la levée gauche, plus étroite; (2) le dépôt d'un lobe HARP par les écoulements non-chenalisés en aval du point d'avulsion, et l'abandon de l'ancien chenal; (3) l'initiation d'un nouveau système chenal-levée. La migration systématique du chenal vers le nord est influencée par l'assymétrie des levées (donc par la force de Coriolis), et confinée entre les grandes levées de la phase initiale du chenal du Danube, au sud, et le relief abrupt de l'éventail du Dniepr au nord. La structure sédimentaire du chenal du Danube indique que les surfaces érosives à l'intérieur du remplissage du chenal se seraient formées en réponse aux avulsions, du fait de l'ajustement du profil du chenal après la rupture d'une levée. Les sédiments du chenal érodés au cours de ce processus ont formé les lobes HARP. Quand le chenal a retrouvé son profil d'équilibre, un système chenal-levée s'est développé en aval du point d'avulsion au dessus du lobe HARP, mais aussi en amont de ce point, où il se trouve confiné dans la vallée érosive. Les incisions fluviatiles identifiés sur la plate-forme continentale et la position de la ligne de côte pendant la dernière période d'activité du chenal du Danube montrent que le paléo-Danube se dirigeait directement vers la tête du canyon du Danube. Son embouchure était située à proximité du canyon, qui alimentait le chenal du Danube. Cependant, les courants hyperpycnaux devaient prévaloir dans le milieu de salinité réduite qui caractérisait la mer Noire lors des périodes actives de l'éventail. Ces conditions auraient favorisé la mise en place d'un système quasi-continu fleuve-canyon-éventail profond, qui contrôlait le transfert des sédiments entre la côte et le bassin profond.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2002/these-1206.pdf
http://archimer.ifremer.fr/doc/00000/1206/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We sought transversotrematid trematodes from French Polynesian fishes by examining 304 individual scaled fishes of 53 species from seven families known to harbour the family elsewhere. A single species was found at two locations in the Tuamotus Archipelago on two species of Chaetodontidae (Chaetodon auriga and Chaetodon ephippium) and one species of Lutjanidae (Lutjanus gibbus). The species closely resembles Transversotrema borboleta Hunter & Cribb, 2012 from chaetodontids and lutjanids of the northern Great Barrier Reef (GBR) but differs from it consistently in 8 base positions of ITS2 rDNA. This level of variation exceeds that between some clearly morphologically distinct pairs of species of Transversotrema and the form from French Polynesia is thus interpreted as a distinct, though cryptic, species and named Transversotrema polynesiae n. sp. The new species forms part of a complex of species, here characterised as the T. borboleta complex, associated with chaetodontids and lutjanids in the tropical Indo-West Pacific. Most of the putative species within this complex are yet to be described. Comparison of identical numbers of matched samples of fishes from French Polynesia, Heron Island (southern GBR) and Lizard Island (northern GBR) revealed 1, 4 and 10 species of Transversotrema respectively suggesting that the French Polynesian fauna is depauperate for this family. In addition to those species apparently missing from suitable hosts in French Polynesia, several species from further west infect fishes (especially Nemipteridae) that are themselves absent from French Polynesia. This dramatic east–west decline in richness contrasts strongly with what is known for monogeneans, which appear to maintain their richness over the same scale, and is more precipitate than is known for other groups of trematodes. The decline might be explained in part by the absence of the as yet unknown first intermediate hosts in French Polynesia. However, we predict that it is explained by other life cycle traits. We hypothesise that the characters of large short-lived cercariae, short-lived miracidia, the absence in the life-cycle of second intermediate hosts that are capable of transporting the species, and definitive and first intermediate hosts that have limited vagility combine to give marine Transversotrematidae limited dispersal capacity and a propensity for localised speciation.
ISSN: 1383-5769

hal-01333467
https://hal-univ-perp.archives-ouvertes.fr/hal-01333467
DOI : 10.1016/j.parint.2013.11.009

Éditeur(s) : Inter-Research
Résumé : The marine environment is of special interest for studying hybridization between closely related taxa because of the high dispersal potential of planktonic larvae, such as those of most bivalve species. The oysters Crassostrea angulata and C. gigas are known to be very close genetically and entirely inter-fertile under controlled conditions. However, hybridization in the wild had not been investigated, mainly due to the lack of nuclear diagnostic markers. In the present paper, we first estimated genetic differentiation between these 2 closely related taxa using 8 microsatellite markers. Interestingly, 5 markers displayed significant differences of allele size between taxa. The subsequent sequencing of alleles of one of these microsatellites showed several mutational events, which suggested null alleles and homoplasy. The presence of 1 insertion/deletion event in its 5' flanking sequence enabled us to design a new bi-allelic ('C' and 'NC') nuclear PCR-restriction fragment length polymorphism (-RFLP) marker (CG44R). This, together with a mitochondrial DNA marker, was used to analyze populations of C. angulata and C. gigas. The CG44R allele frequencies were very different between C. angulata (f[C] = 0.91) and C. gigas (f[NC] = 0.92) populations. This analysis also provided evidence for hybridization between C. angulata and C. gigas in a wild Portuguese population where the 2 taxa are in contact due to recent transportation of C. gigas stocks for aquacultural production. Our results represent the first indication of hybridization between these 2 taxa in the natural environment, and contribute to knowledge of the evolutionary history of the Crassostrea genus.
Marine Ecology Progress Series (0171-8630) (Inter-Research), 2004 , Vol. 272 , P. 141-152

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2004/publication-3355.pdf
http://archimer.ifremer.fr/doc/00000/3355/

Éditeur(s) : Université des Antilles et de la Guyane
Résumé : L’organisation et de la gestion des espaces publics en milieu urbain est au centre des préoccupations de la puissance publique. Cet intérêt est lié dans les pays en développement aux nombreux dysfonctionnements recensés dans la ville. Ces difficultés entretenues par la démographie galopante, l’urbanisation informelle et à l’accroissement des activités industrielles, commerciales entre autres. A Dakar, la question de la mobilité urbaine est exacerbée par les puissants mouvements pendulaires entre la ville centrale et la périphérie amplifiés par les stationnements anarchiques et par l’inorganisation des modes de transports urbains.Le type d’espace public choisi pour cet article est une gare routière située au cœur du Plateau de Dakar : Petersen. Elle apparaît comme l’une des plus importantes gares routières du pays, surtout en termes de fréquentation avec plus de 50 000 personnes par jour. Le mode de gestion appliqué ici est la concession, une convention par laquelle la puissance publique confie la gestion de l’équipement à la SAGES une structure privée prenant en charge les intérêts parfois très contradictoires des différents acteurs.
The organization and management of public spaces in urban areas is a central concern of public authorities. This interest is linked in developing countries with numerous shortcomings identified in the city. These difficulties sustained by massive population growth, urbanization informal, and increased industrial activities, commercial and others. In Dakar, the question of urban mobility is exacerbated by the significant commuting between the city center and the periphery that are amplified by the chaotic parking lots and the disorganization of urban transport modes.The type of public space chosen for this article is a bus station in the heart of the Plateau de Dakar: Petersen. It appears as one of the largest bus stations in the country, especially in terms of attendance with over 50,000 people per day.The management method applied here is the concession, an agreement by which the public entrusts the management of equipment at the SAGES, a private organization that supports some very conflicting interests of different actors.

urn:doi:10.4000/etudescaribeennes.4445
http://etudescaribeennes.revues.org/4445

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The contourite depositional system (CDS) along the southwestern Iberian Margin (SIM), within the Gulf of Cadiz and offshore areas of western Portugal bear the unmistakable signal of Mediterranean Outflow Water (MOW) exiting the Strait of Gibraltar. This locality records key information concerning the effects of tectonic activity on margin sedimentation, the effects of MOW dynamics on Atlantic circulation, and how these factors may have influenced global climate. Over the last four decades, numerous studies have been conducted on the late Miocene, Pliocene and Quaternary sedimentary stacking pattern of Neogene basins along the SIM for both academic and resources exploration purposes. However, understanding of the region rests primarily on basic seismic stratigraphy calibrated with limited data from only a few exploration wells. The Integrated Ocean Drilling Program (IODP) Expedition 339 recently drilled five sites in the Gulf of Cadiz and two sites on the western Iberian margin. The integration of core and borehole data with other geophysical databases leads us to propose a new stratigraphic framework. Interpretation of IODP Exp. 339 data along with that from industry sources and onshore outcrop analysis helps refine our understanding of the SIM's sedimentary evolution.We identify significant changes in sedimentation style and dominant sedimentary processes, coupled with widespread depositional hiatuses along the SIM within the Cadiz, Sanlucar, Doñana, Algarve and Alentejo basins. Following the 4.5 Ma cessation of a previous phase of tectonic activity related to the Miocene–Pliocene boundary, tectonics continued to influence margin development, downslope sediment transport and CDS evolution. Sedimentary features indicate tectonic pulses of about 0.8–0.9 Ma duration with a pronounced overprint of ~ 2–2.5 Ma cycles. These more protracted cycles relate to the westward rollback of subducted lithosphere at the convergent Africa-Eurasia plate boundary as its previous NW–SE compressional regime shifted to a WNW–ESE direction. Two major compressional events affecting to the Neogene basins at 3.2–3 Ma and 2–2.3 Ma help constrain the three main stages of CDS evolution. The stages include: 1) the initial-drift stage (5.33–3.2 Ma) with a weak MOW, 2) a transitional-drift stage (3.2–2 Ma) and 3) a growth-drift stage (2 Ma-present time) with enhanced MOW circulation into the Atlantic and associated contourite development due to greater bottom-current velocity. Two minor Pleistocene discontinuities at 0.7–0.9 Ma and 0.3–0.6 Ma record the effects of renewed tectonic activity on basin evolution, appearing most prominently in the Doñana basin. Several discontinuities bounding major and minor units appear on seismic profiles. Quaternary records offer the clearest example of this, with major units of about 0.8–0.9 Ma and sub-units of 0.4–0.5 Ma. Sedimentation is controlled by a combination of tectonics, sediment supply, sea-level and climate. This research identifies time scales of tectonic controls on deep-marine sedimentation, specifically over periods of 2.5–> 0.4 Ma. Shorter-term climatic (orbital) mechanisms control sedimentation at time scales of ≤ 0.4 Ma. The role of bottom water circulation and associated processes in shaping the seafloor and controlling the sedimentary stacking pattern on continental margins has to be seriously reconsidered in future multidisciplinary studies. This is not only because of the common occurrence of sandy contourite deposits in deep water setting and their economic interest for hydrocarbon exploration, but principally because they archive the heartbeat of the interior Earth and therefore have important sedimentary and paleoceanographic implications.
ISSN: 0025-3227

hal-01356166
https://hal.archives-ouvertes.fr/hal-01356166
DOI : 10.1016/j.margeo.2015.09.013

Éditeur(s) : Springer
Résumé : While it is well known that the ocean is one of the most important component of the climate system, with a heat capacity 1,100 times greater than the atmosphere, the ocean is also the primary reservoir for freshwater transport to the atmosphere and largest component of the global water cycle. Two new satellite sensors, the ESA Soil Moisture and Ocean Salinity (SMOS) and the NASA Aquarius SAC-D missions, are now providing the first space-borne measurements of the sea surface salinity (SSS). In this paper, we present examples demonstrating how SMOS-derived SSS data are being used to better characterize key land–ocean and atmosphere–ocean interaction processes that occur within the marine hydrological cycle. In particular, SMOS with its ocean mapping capability provides observations across the world’s largest tropical ocean fresh pool regions, and we discuss from intraseasonal to interannual precipitation impacts as well as large-scale river runoff from the Amazon–Orinoco and Congo rivers and its offshore advection. Synergistic multi-satellite analyses of these new surface salinity data sets combined with sea surface temperature, dynamical height and currents from altimetry, surface wind, ocean color, rainfall estimates, and in situ observations are shown to yield new freshwater budget insight. Finally, SSS observations from the SMOS and Aquarius/SAC-D sensors are combined to examine the response of the upper ocean to tropical cyclone passage including the potential role that a freshwater-induced upper ocean barrier layer may play in modulating surface cooling and enthalpy flux in tropical cyclone track regions.
Surveys In Geophysics (0169-3298) (Springer), 2014-05 , Vol. 35 , N. 3 , P. 681-722

Droits : Springer Science+Business Media Dordrecht 2013
http://archimer.ifremer.fr/doc/00152/26334/24430.pdf
DOI:10.1007/s10712-013-9244-0
http://archimer.ifremer.fr/doc/00152/26334/

Éditeur(s) : Springer
Résumé : Large benthic foraminifers are considered to be good indicators of shallow marine carbonate environments in fossil series. Over the last 50 years, the palaeoenvironment of Tertiary Nummulites accumulations has been a matter of debate, particularly because of difficulties in interpreting these deposits, and in this way, the absence of analogues in present-day seas does not help. The aim of this paper is to insight the different ways Nummulites tests and clasts may accumulate according to their hydrodynamic behaviour. Based on experimental measurements and on SEM observations, it appears that the high primary skeletal porosity of Nummulites made them easily transportable. The calculated threshold shear velocities confirm that large-sized Nummulites can be moved by weak wave-driven currents. This peculiar hydrodynamic behaviour of Nummulites could explain the diversity of depositional models. Depending on local hydrodynamic conditions, autochthonous Nummulites deposits can be preserved as in situ winnowed bioaccumulations or be accumulated offshore, onshore or alongshore, away from the original biotope.
Facies (0172-9179) (Springer), 2006-05 , Vol. 52 , N. 2 , P. 221-235

Droits : Springer-Verlag 2005
http://archimer.ifremer.fr/doc/00085/19597/17234.pdf
DOI:10.1007/s10347-005-0035-z
http://archimer.ifremer.fr/doc/00085/19597/

Éditeur(s) : Université de Bretagne Occidentale
Résumé : Ce travail contient les résultats d'une analyse comparative menée entre des séries ophiolitifères de la nappe des schistes lustrés dans la région du Queyras et des données sous-marines. Ces dernières comprennent : 1) Une observation de la croûte océanique du Banc de Gorringe (Sw Portugal) effectuée par l'auteur lors d'une plongée du submersible CYANA. 2) Une revue des dragages, carottages et forages réalisés dans diverses provinces des océans actuels et concernant toutes les manifestations du démantèlement et du transport de matériaux de la croûte et du manteau océaniques.

Droits : UBO
http://archimer.ifremer.fr/doc/00034/14521/11833.pdf
http://archimer.ifremer.fr/doc/00034/14521/

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : Climate may act on the dispersal and connectivity of marine populations through changes in the oceanic circulation and temperature, and by modifying species' prey and predator distributions. As dispersal and connectivity remain difficult to assess in situ, a first step in studying the effects of climate change can be achieved using biophysical models. To date, only a few biophysical models have been used for this purpose. Here we review these studies and also include results from other recent modelling efforts. We show that increased sea temperature, a major change expected under climate warming, may impact dispersal and connectivity patterns via changes in reproductive phenology (e.g., shift in the spawning season), transport (e.g., reduced pelagic larval duration under faster development rates), mortality (e.g., changes in the exposure to lethal temperatures), and behaviour (e.g.. increased larval swimming speed). Projected changes in circulation are also shown to have large effects on the simulated dispersal and connectivity patterns. Although these biophysical modelling studies are useful preliminary approaches to project the potential effects of climate change, we highlight their current limitations and discuss the way forward, in particular the need for adequate coupled hydrodynamic-biogeochemical simulations using atmospheric forcing from realistic climate change scenarios. (C) 2010 Elsevier Ltd. All rights reserved.
Progress In Oceanography (0079-6611) (Pergamon-elsevier Science Ltd), 2010-10 , Vol. 87 , N. 1-4 , P. 106-113

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00031/14176/11522.pdf
DOI:10.1016/j.pocean.2010.09.005
http://archimer.ifremer.fr/doc/00031/14176/