Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In Western Mediterranean, the Rif belt in Morocco is part of the Gibraltar Arc built during the Tertiary in the framework of Eurasia-Africa convergence. The structural and metamorphic evolution of the internal units of this belt as well as their timing, crucial to constrain the geodynamic evolution of the Alboran Sea, is still largely debated.Our study on the Ceuta Peninsula (Northern Rif) provides new structural, petrological and geochronological data (U-Th-Pb, Ar-Ar), which allow to precise the tectono-metamorphic evolution of the Lower Sebtides metamorphic units with:(1) a syn-metamorphic thrusting event developed under granulite facies conditions (7–10 kbar and 780–820 °C). A major thrust zone, the Ceuta Shear Zone, drove the emplacement of metapelites and peridotitic lenses from the Ceuta Upper Unit over the orthogneisses of the Monte Hacho Lower Unit. This compressional event ended during the Upper Oligocene.(2) an extensional event developed at the boundary between amphibolite and greenschist facies conditions (400–550 °C and 1–3 kbar). During this event, the Ceuta Shear Zone has been reactivated as a normal fault. Normal ductile shear zones contributed to the final exhumation of the metamorphic units during the Early Miocene.We propose that the compressional event is related to the formation of an orogenic wedge located in the upper plate, in a backward position, of the subduction zone driving the geodynamic evolution of the Alboran domain. In this context, the episode of lithospheric thinning could be related to the opening of the Alboran basin in a back-arc position.Furthermore, unlike the previous models proposed for the Rif belt, the tectonic coupling between mantle peridotites and crustal metamorphic rocks occurred in Ceuta Peninsula at a depth of 20–30 km under high temperature conditions, before the extensional event, and thus cannot be related to the back-arc extension.
ISSN: 0040-1951

insu-01682810
https://hal-insu.archives-ouvertes.fr/insu-01682810
DOI : 10.1016/j.tecto.2017.11.028

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
The Ama Drime range located at the transition between the high Himalayan range and south Tibet is a N-S active horst that offsets the South Tibetan Detachment System (STDS). Within the horst, a paragneissic unit, possibly attributed to the upper Himalayan crystalline series, overly the lower Himalayan crystalline series Ama Drime orthogneissic unit containing large metabasite layers and pods that have experienced pressure >= 1.4 GPa. Combining structural analysis with new and published pressure-temperature (P-T) estimates as well as U-Th/Pb, Ar-39/Ar-40 and (U-Th)/He ages, the P-T-deformation-time (P-T-D-t) paths of the main units within and on both sides of the horst are reconstructed. They imply that N-S normal faults initiated prior to 11 Ma and have accounted for a total exhumation <= 0.6 GPa (22 km) that probably occurred in two phases: the first one until similar to 9 Ma and the second one since 6 to 4 Ma at a rate of similar to 1 mm/yr. In the Ama Drime unit, 1 to 1.3 GPa (37 to 48 km) of exhumation occurred after partial melting since similar to 30 Ma until similar to 13 Ma, above the Main Central Trust (MCT) and below the STDS when these two fault systems were active together. The switch from E-W (STDS) to N-S (Ama Drime horst) normal faulting between 13 and 12 Ma occurs at the time of propagation of thrusting from the MCT to the Main Boundary Thrust. These data are in favor of a wedge extrusion or thrust system rather than a crustal flow model for the building of the Himalaya. We propose that the kinematics of south Tibet Cenozoic extension phases is fundamentally driven by the direction and rate of India underthrusting.
ISSN: 0278-7407

hal-00486405
https://hal.archives-ouvertes.fr/hal-00486405
DOI : 10.1029/2009TC002551

Éditeur(s) : HAL CCSD
Résumé : Understanding of the mechanisms driving diversification of species is a significant way to improve the management of ecosystems, predict the impacts of climate change and understand the actual and past biodiversity level. The aim of this thesis is to understand and comprehend genetic mechanisms behind the diversification of species in the presence of gene flow. This thesis is focused on the biological model Symphonia globulifera, which presents two ecotypes: the S.globulifera, specialist of seasonally flooded lowlands and S.sp1, specialist of terra firme. These two ecotypes show low genetic differentiation, despite the presence of two apparent phenotypes. A first part of this thesis was to test the presence of local adaptation of this using reciprocal transplant experiment gardens, allowing the understanding of the ecotypes distributions in their natural habitats. Then, this local adaptation in the presence of gene flow, directed me to the regulation of gene methylation in order to see the role this brand of epigenetics can have in the divergence of the ecotypes. In a third part of the thesis, new generation sequencing of the transcriptome ecotypes in reciprocal gardens transplantations allowed me to show the evidence of gene regulation to differentiate the ecotypes. This work thesis is based on phenotype records data, AFLP genotyping and high-throughput sequencing of the transcriptome, in order to show the important value of gene regulation in the divergence of the locally adapted ecotypes, and a weak role of DNA methylation in the establishment of local adaptation.
Connaitre et appréhender les mécanismes de la diversification des espèces est important pour la gestion des écosystèmes, la prévision des impacts des changements climatiques et la compréhension de la biodiversité actuelle et passée. Le but de cette thèse est de comprendre et de déceler les mécanismes génétiques à l’origine de la diversification des espèces en présence de flux de gènes. Cette thèse se focalise sur le modèle biologique Symphonia globulifera, qui compte deux écotypes : le S.globulifera spécialiste de la terra firme et le S.sp1, spécialiste des bas-fonds. Ces deux écotypes montrent une faible différenciation génétique, malgré la présence de deux phénotypes différents.Une première étape a été de mettre en évidence la présence d’une adaptation locale au sein de cette espèce, par le biais d’une expérimentation de jardins de transplantation réciproques, permettant d’expliquer la répartition des écotypes dans leur habitat naturel. Ensuite, dans le but d’identifier les mécanismes sous-jacent à cette adaptation locale, j’ai testé l’hypothèse que la méthylation des gènes pourrait être une marque de l’épigénétique contribuant à la divergence des écotypes, par l’utilisation d’enzyme sensibles à la méthylation dans un protocole de génotypage AFLP. Enfin, un séquençage haut-débit du transcriptome des écotypes en jardins de transplantation réciproques m’a permis de mettre en évidence une expression différentielle des gènes entre les écotypes, qui pourrait expliquer les différences phénotypiques observées entre les écotypes malgré une faible différentiation génétique. Ces travaux de thèse s’appuie, ainsi, sur des données de traits phénotypiques, de génotypage AFLP et de séquençage à haut débit du transcriptome pour montrer la valeur importante de la régulation des gènes dans la divergence des écotypes adaptés localement, et un faible rôle de la méthylation de l’ADN dans l’établissement cette adaptation locale.
https://tel.archives-ouvertes.fr/tel-01405400

NNT : 2015YANE0005
tel-01405400
https://tel.archives-ouvertes.fr/tel-01405400
https://tel.archives-ouvertes.fr/tel-01405400/document
https://tel.archives-ouvertes.fr/tel-01405400/file/these_-_tinaut.pdf

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Everyone is subject to environmental exposures from various sources, with negative health impacts (air, water and soil contamination, noise, etc.or with positive effects (e.g. green space). Studies considering such complex environmental settings in a global manner are rare. We propose to use statistical factor and cluster analyses to create a composite exposure index with a data-driven approach, in view to assess the environmental burden experienced by populations. We illustrate this approach in a large French metropolitan area. The study was carried out in the Great Lyon area (France, 1.2 M inhabitants) at the census Block Group (BG) scale. We used as environmental indicators ambient air NO2 annual concentrations, noise levels and proximity to green spaces, to industrial plants, to polluted sites and to road traffic. They were synthesized using Multiple Factor Analysis (MFA), a data-driven technique without a priori modeling, followed by a Hierarchical Clustering to create BG classes. The first components of the MFA explained, respectively, 30, 14, 11 and 9% of the total variance. Clustering in five classes group: (1) a particular type of large BGs without population; (2) BGs of green residential areas, with less negative exposures than average; (3) BGs of residential areas near midtown; (4) BGs close to industries; and (5) midtown urban BGs, with higher negative exposures than average and less green spaces. Other numbers of classes were tested in order to assess a variety of clustering. We present an approach using statistical factor and cluster analyses techniques, which seem overlooked to assess cumulative exposure in complex environmental settings. Although it cannot be applied directly for risk or health effect assessment, the resulting index can help to identify hot spots of cumulative exposure, to prioritize urban policies or to compare the environmental burden across study areas in an epidemiological framework.Journal of Exposure Science and Environmental Epidemiology advance online publication, 24 September 2014; doi:10.1038/jes.2014.66.
ISSN: 1559-0631

hal-01069587
https://hal.archives-ouvertes.fr/hal-01069587
https://hal.archives-ouvertes.fr/hal-01069587/document
https://hal.archives-ouvertes.fr/hal-01069587/file/Article_multiexpo_20140708_c.pdf
DOI : 10.1038/jes.2014.66

Éditeur(s) : HAL CCSD National Shellfisheries Association
Résumé : International audience
Monitoring gonad maturation for protandrous and functional hermaphrodite species such as the giant clam Tridacna maxima is difficult due to the juxtaposition and relative proportion of male and female tissues in the gonad [gonadal sex ratio (GSR)]. Here, the relevance of the widely used gonadosomatic index (GSI) as proxy of giant clam gonad maturation is tested with a large dataset (n ¼ 265). Gonadosomatic index is compared with other indices, namely the proportion of the male part harboring spermatozoids, the proportion of empty oocyte follicles, the mean oocyte diameter, and the oocyte elongation. At gonad scale, high index variability highlighted partial spawning. At individual scale, male and female maturation proxies were contrasted, showing either asynchronous emissions of male and female gametes or contrasted spermatogenesis and oogenesis duration. The GSI was mostly driven by the number and diameter of oocytes and therefore it is recommended here as primary proxy for female maturity. Except for the oocyte elongation, all indices were affected by the GSR, which ruled out drawing conclusions at population scale. These results highlight the need for maturation stage proxies that are optimized for functional hermaphrodite species.
ISSN: 0730-8000

hal-01613648
https://hal.archives-ouvertes.fr/hal-01613648
https://hal.archives-ouvertes.fr/hal-01613648/document
https://hal.archives-ouvertes.fr/hal-01613648/file/Gaertner-Mazouni-2016-eio.pdf
DOI : 10.2983/035.035.0107

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : The fixation of carbon in tropical forests mainly occurs through the production of wood and leaves, both being the principal components of net primary production. Currently field and satellite observations are independently used to describe the forest carbon cycle, but the link between satellite-derived forest phenology and field-derived forest productivity remains opaque. We used a unique combination of a MODIS enhanced vegetation index (EVI) dataset, a wood production model based on climate data and direct litterfall observations at an intra-annual timescale in order to question the synchronism of leaf and wood production in tropical forests. Even though leaf and wood biomass fluxes had the same range (respectively 2.4 +/- 1.4 and 2.2 +/- 0.4 Mg C ha(-1) yr(-1)), they occurred separately in time. EVI increased with leaf renewal at the beginning of the dry season, when solar irradiance was at its maximum. At this time, wood production stopped. At the onset of the rainy season, when new leaves were fully mature and water available again, wood production quickly increased to reach its maximum in less than a month, reflecting a change in carbon allocation from short-lived pools (leaves) to long-lived pools (wood). The time lag between peaks of EVI and wood production (109 days) revealed a substantial decoupling between the leaf renewal assumed to be driven by irradiance and the water-driven wood production. Our work is a first attempt to link EVI data, wood production and leaf phenology at a seasonal timescale in a tropical evergreen rainforest and pave the way to develop more sophisticated global carbon cycle models in tropical forests.
ISSN: 1726-4170

hal-01268497
https://hal.archives-ouvertes.fr/hal-01268497
DOI : 10.5194/bg-10-7307-2013
PRODINRA : 256018

Éditeur(s) : HAL CCSD
Résumé : International audience
This communication reports on a field experiment carried out on a microtidal beach in Camargue, France. The analysis is built on the initial work presented by Sous et al. (2016) on swash-groundwater dynamics. The analysis of a cross-shore network of buried pressure sensors allows to monitor the watertable dynamics over the full 2013-2014 winter season. The pressure head gradients are observed to be primarily seaward, forced by a higher level at the landward boundary. The groundwater flux is driven by the relative fluctuations of Still Water Level and inland elevations. Rain and tides have a little effect. A nearly isolated groundwater circulation is driven by wave activity below the swash zone whatever the overall watertable gradient. Estimations of beach groundwater discharge over the Gulf of Beauduc reveal the importance of beach groundwater in the exchanges between coastal aquifer and open sea.
Coastal Dynamics 2017
Helsingor, Denmark

hal-01562908
https://hal.archives-ouvertes.fr/hal-01562908

Éditeur(s) : HAL CCSD
Résumé : International audience
We instrumented a car simulator by gathering low level data and fed it to an artificial neural network in order to perform blood alcohol content (BAC) estimations. The results depend on the quality of the data extraction and processing, and also on the selected inputs. We explain our data extraction and processing methodology, and how we used it to generate reliable and comparable features. At last, we describe the performances of individual features and how they combine. In the end, the prototype was able to accurately estimate the BAC value of a subject after being trained with driving samples of this subject with various BAC values.
Proceedings of ACHI 2013, The Sixth International Conference on Advances in Computer-Human Interactions
Nice, France

hal-00850137
https://hal.archives-ouvertes.fr/hal-00850137

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Necroptosis is a programmed cell death pathway that has been shown to be of central pathophysiological relevance in multiple disorders (hepatitis, brain and cardiac ischemia, pancreatitis, viral infection and inflammatory diseases). Necroptosis is driven by two serine threonine kinases, RIPK1 (Receptor Interacting Protein Kinase 1) and RIPK3, and a pseudo-kinase MLKL (Mixed Lineage Kinase domain-Like) associated in a multi-protein complex called necrosome. In order to find new inhibitors for use in human therapy, a chemical library containing highly diverse chemical structures was screened using a cell-based assay. The compound 6E11, a natural product derivative, was characterized as a positive hit. Interestingly, this flavanone compound: inhibits necroptosis induced by death receptors ligands TNF-α (Tumor Necrosis Factor) or TRAIL (TNF-Related Apoptosis-Inducing Ligand); is an extremely selective inhibitor, among kinases, of human RIPK1 enzymatic activity with a nM Kd; has a non-ATP competitive mode of action and a novel putative binding site; is weakly cytotoxic towards human primary blood leukocytes or retinal pigment epithelial cells at effective concentrations; protects human aortic endothelial cells (HAEC) from cold hypoxia/reoxygenation injury more effectively than necrostatin-1 (Nec-1) and Nec-1s. Altogether, these data demonstrate that 6E11 is a novel potent small molecular inhibitor of RIPK1-driven necroptosis.
ISSN: 2045-2322

hal-01616456
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01616456
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01616456/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01616456/file/s41598-017-12788-4.pdf
DOI : 10.1038/s41598-017-12788-4

Éditeur(s) : HAL CCSD
Résumé : International audience
Symbiosis is a widespread phenomenon in the biosphere. In marine benthic environments breakdown of symbiosis is responsible for coral bleaching and dramatically affects coral reef ecosystems functioning [1]. In the water column, planktonic organisms are key component of pelagic ecosystems and a number of species form mutualistic association with microalgae forming a photosymbiosis [2]. Here we intended to investigate the genetic basis of photosymbiosis, through a transcriptomic approach on marine plankton organisms. We focused more specifically on associations occurring between radiolarian host (protist, zooplankton) and dinoflagellates symbiont (protist, phytoplankton) living inside the host cell. It has recently been highlighted that these holobionts are widespread in oligotrophic open oceans and there are also evidences of their fundamental implication in biogeochemical carbon, silica and strontium cycles [3, 4, 5, 6]. RNA-seq technologies allow obtaining an unprecedented amount of data for unicellular organisms isolated from the environment [7]. The study of such non-model holobionts datasets requires de novo assembly, which implies considerable computational resources and the potential production of chimeric sequences [8, 9].We therefore developed an original strategy aiming at accelerating and improving de novo assembly for holobiont datasets. We chose SIMKA [10] a fast kmer-based method initially developed to estimate the similarity between numerous metagenomic datasets, and which has been recently adapted to extract their common sequences. As our symbionts are identified, we used SIMKA to compare our holobionts transcriptomes to publicly available dinoflagellates transcriptomes [11] generating two datasets, one composed of reads from the symbionts and another with reads from the host (for which no reference data are currently available). Independent assemblies were then performed in parallel, accelerating the study process, and minimizing the proportion of resulting chimeric sequences. Our strategy produced a unique and comprehensive genomic dataset for Radiolaria [12, 13], and offers a pragmatic, large scale, comparison strategy to assemble and study holobionts [9]. Our new sequences obtained from holobionts study will be used for phylogenomics investigation, as reference for environmental metagenomic studies and ultimately to understand and characterize the molecular basis of symbiotic relationships in the plankton.Bibliografic references :[1] Simon K. Davy, Denis Allemand, and Virginia M. Weis. “Cell Biology of Cnidarian-Dinoflagellate Symbiosis”. In: Microbiology and Molecular Biology Reviews 76.2 (June 1, 2012), pp. 229–261. issn: 1092-2172, 1098- 5557. doi: 10.1128/MMBR.05014-11.[2] Janouškovec, J. et al. “Major transitions in dinoflagellate evolution unveiled by phylotranscriptomics”. in: PNAS 201614842 (2016). doi:10.1073/pnas.1614842114[3] Tristan Biard et al. “In situ imaging reveals the biomass of giant protists in the global ocean”. In: Nature advance online publication (Apr. 20, 2016). issn: 0028-0836. doi: 10.1038/nature17652.[4] Lionel Guidi et al. “Plankton networks driving carbon export in the olig- otrophic ocean”. In: Nature 532.7600 (Apr. 28, 2016), pp. 465–470. issn: 0028-0836. doi: 10.1038/nature16942.[5] Diane K. Stoecker et al. “Acquired phototrophy in aquatic protists”. In: Aquatic Microbial Ecology 57.3 (Nov. 24, 2009), pp. 279–310. doi: 10.3354/ame01340.[6] Johan Decelle et al. “An original mode of symbiosis in open ocean plankton”. In: Proceedings of the National Academy of Sciences 109.44 (Oct. 30, 2012), pp. 18000–18005. issn: 0027-8424, 1091-6490. doi: 10. 1073/pnas.1212303109.[7] Sergio Balzano et al. “Transcriptome analyses to investigate symbiotic relationships between marine protists”. In: Frontiers in Microbiology 6 (Mar. 17, 2015). issn: 1664-302X. doi: 10.3389/fmicb.2015.00098.[8] Li, B. et al. “Evaluation of de novo transcriptome assemblies from RNA-Seq data”. In: Genome Biology 15, 553 (2014).[9] Sangwan, N., Xia, F. & Gilbert, J. A. “Recovering complete and draft population genomes from metagenome datasets”. In: Microbiome 4, 8 (2016).[10] Gaëtan Benoit et al. “Multiple comparative metagenomics using mul- tiset k -mer counting”. In: PeerJ Computer Science 2 (Nov. 14, 2016). doi: 10.7717/peerj-cs.94.[11] Patrick J. Keeling et al. “The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): Illuminating the Functional Diversity of Eukaryotic Life in the Oceans through Transcriptome Sequencing”. In: PLOS Biol 12.6 (June 2014), e1001889. issn: 1545-7885. doi: 10.1371/journal.pbio.1001889.[12] Burki, F. et al. “Evolution of Rhizaria: new insights from phylogenomic analysis of uncultured protists”. In BMC Evolutionary Biology 10, 377 (2010).
International Conference on Holobionts
Paris, France

hal-01575069
https://hal.inria.fr/hal-01575069

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : L’article s’intéresse à la migration des Caribéens vers l’Éthiopie, et notamment celle des Rastafariens qui se définissent comme de « vrais Éthiopiens » et se disent « rapatriés » en Éthiopie. En dépit de leur nombre limité, ils n’en sont pas moins importants, car ils illustrent la persistance et les transformations des imaginaires et idéologies liant les Noirs du monde à l’Éthiopie ainsi qu’un pan méconnu des mobilités caribéennes qui, se dirigeant vers l’Afrique, se découvrent complètement à contre-courant.
The article deals with Caribbean migration towards Ethiopia, and especially the one of Rastafarians who define themselves as ‘true Ethiopians’ and ‘repatriates’ in Ethiopia. Despite their limited number, their experience is nonetheless important as it reveals the persistence and change in imaginaries and ideologies linking black all over the world to Ethiopia as well as unknown Caribbean mobility towards Africa, a mobility which is driven against the current.

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.942
http://journals.openedition.org/etudescaribeennes/942

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
This study investigates three-dimensional flow modes of orogenic plateaus by means of physical modeling. Experiments consist of shortening two contiguous lithospheres of contrasting strength, one being a weak plateau-type lithosphere and the other a strong craton-type lithosphere. The lateral boundaries are either totally confined or allow escape toward a lateral foreland on one side. Two synconvergence flow regimes are distinguished, which are governed by the balance between the gravity potential and the strength of the plateau crust and the resistance of its lateral foreland. The first regime implies transversal (orogen-normal) injection of plateau lower crust into the collision zone as a result of confinement of the plateau by an increasingly stiffer lateral boundary. As a precursor mechanism to channel flow, transversal injection responds to downward thickening of the plateau crust that is forcedly extruded into the orogenic wedge. The second regime is that of collapse-driven lateral escape of the plateau. This regime is established after a threshold is attained in the interplate coupling in the collision zone, which allows the gravity potential of the plateau to overcome the resistance of its lateral boundary. Under the collapse-driven escape regime (orogen parallel), such as that governing Tibet during the last 13 Ma, most of the convergence in the plateau and the top and rear of the collisional wedge is transformed into lateral flow and extension.
ISSN: 0148-0227

hal-01229107
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01229107
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01229107/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01229107/file/2015JB012110_revised.pdf
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01229107/file/SupplementaryMaterial_final.pdf

Éditeur(s) : ISTPM
Résumé : The dwindling of the stocks of some marine animals traditionally fished is driving the producers to consider the exploitation of species which were seen as of lesser interest up to now. Among the latter, cephalopods hold a specific position. In the first place, they are not a new resource so to speak, having been eaten in Asian and Mediterranean countries for a long time, and, above all, they've been the object of a growing interest for a few years now. It is encouraging to see that this tendency is very distinct in our country where it can be thought that producers and consumers are now aware of the value of this abounding species. The actions aimed at optimising their exploitation are thus facilitated but they suffer from the imprecision of the statistical data on the fisheries. This data is indeed necessary to evaluate the availability of the stocks and to direct the production through a rational management.
L'amenuisement des stocks de certains animaux marins traditionnellement pêchés amène les producteurs à envisager l'exploitation d'espèces jusqu'à présent considérées comme de moindre intérêt. Parmi ces dernières, les céphalopodes occupent une place particulière. En premier lieu, ils ne constituent pas à proprement parler une ressource nouvelle, ayant de tous temps été consommés dans les pays asiatiques et méditerranéens, et surtout, depuis quelques années, ils suscitent un intérêt croissant dans nombre de pays. II est encourageant de constater que cette tendance est particulièrement nette dans notre pays où tout porte à croire •que producteurs et consommateurs ont pris conscience de la valeur de cette ressource disponible en abondance. Les actions destinées à optimaliser l'exploitation en sont facilitées mais se heurtent à l'imprécision des données statistiques sur les pêcheries. Ces dernières deviennent indispensables si l'on veut évaluer la disponibilité des stocks et orienter la production par une gestion rationnelle. On observe de plus qu'une étendue de plus en plus importante du domaine maritime tombe inévitablement sous le coup de réglementations locales ou internationales qui s'appuient très largement sur les statistiques de pêche. Si nous voulons aider efficacement les producteurs, nous devons disposer de données complètes et objectives. Sans attendre que soit atteint ce degré de précision, nous avons voulu aborder une étape plus élémentaire en réunissant les informations relatives à l'état actuel de l'exploitation des céphalopodes et aux solutions pour la développer. [OCR NON CONTRÔLE]
Science et Pêche (0036-8350) (ISTPM), 1977 , Vol. 265

Droits : Ifremer
http://archimer.ifremer.fr/doc/1977/publication-6666.pdf
http://archimer.ifremer.fr/doc/00000/6666/

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : Plant leaf litter generally decomposes faster as a group of different species than when individual species decompose alone, but underlyingmechanisms of these diversity effects remain poorly understood. Because resource C : N: P stoichiometry (i.e. the ratios of these key elements) exhibits strong control on consumers, we supposed that stoichiometric dissimilarity of litter mixtures (i.e. the divergence in C : N: P ratios among species) improves resource complementarity to decomposers leading to faster mixture decomposition. We tested this hypothesis with: (i) a wide range of leaf litter mixtures of neotropical tree species varying in C : N: P dissimilarity, and (ii) a nutrient addition experiment (C, N and P) to create stoichiometric similarity. Litter mixtures decomposed in the field using two different types of litterbags allowing or preventing access to soil fauna. Litter mixture mass loss was higher than expected from species decomposing singly, especially in presence of soil fauna. With fauna, synergistic litter mixture effects increased with increasing stoichiometric dissimilarity of litter mixtures and this positive relationship disappeared with fertilizer addition. Our results indicate that litter stoichiometric dissimilarity drives mixture effects via the nutritional requirements of soil fauna. Incorporating ecological stoichiometry in biodiversity research allows refinement of the underlying mechanisms of how changing biodiversity affects ecosystem functioning.
ISSN: 0962-8452

hal-01204222
https://hal.archives-ouvertes.fr/hal-01204222
DOI : 10.1098/rspb.2014.1682
PRODINRA : 289918

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Assessing seismic hazards remains one of the most challenging scientific issues in Earthsciences. Deep tectonic processes are classically considered as the only persistentmechanism driving the stress loading of active faults over a seismic cycle. Here we show via amechanical model that erosion also significantly influences the stress loading of thrust faultsat the timescale of a seismic cycle. Indeed, erosion rates of about B0.1–20mmyr1, asdocumented in Taiwan and in other active compressional orogens, can raise the Coulombstress by B0.1–10 bar on the nearby thrust faults over the inter-seismic phase. Masstransfers induced by surface processes in general, during continuous or short-lived andintense events, represent a prominent mechanism for inter-seismic stress loading offaults near the surface. Such stresses are probably sufficient to trigger shallow seismicity orpromote the rupture of deep continental earthquakes up to the surface.
ISSN: 2041-1723

insu-01087103
https://hal-insu.archives-ouvertes.fr/insu-01087103
https://hal-insu.archives-ouvertes.fr/insu-01087103/document
https://hal-insu.archives-ouvertes.fr/insu-01087103/file/Steer2014_NatureComm_accepted.pdf
DOI : 10.1038/ncomms6564

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : Tropical plant diversity is extraordinarily high at both local and regional scales. Many studies have demonstrated that natural enemies maintain local diversity via negative density dependence, but we know little about how natural enemies influence beta-diversity across habitats and/or regions. One way herbivores could influence plant beta-diversity is by driving allocation trade-offs that promote habitat specialization across resource gradients. We therefore predicted that increasing resource availability should be accompanied by increasing herbivory rates and decreasing plant allocation to defense. Second, relative abundances within plant lineages are predicted to reflect patterns of habitat specialization and allocation trade-offs. A phylogenetic context is vital not only to compare homologous plant traits (including defense strategies) across habitat types, but also to connect evolutionary trade-offs to patterns of species diversification in each phylogenetic lineage. We tested these predictions for trees in white-sand, clay terra firme, and seasonally flooded forests in Peru and French Guiana that represent the range of soil fertility, forest structure, and floristic compositions found throughout the Amazon region. We established 74 0.5-ha plots in these habitats and sampled all trees. Within 12 representative plots we marked newly expanding leaves of 394 saplings representing 68 species, including the most abundant species in each plot in addition to species from five focal lineages: Swartzia and Inga (Fabaceae), Protieae (Burseracaeae), Bombacoideae (Malvaceae), and Micropholis (Sapotaceae). We measured total leaf production rates for each sapling and calculated relative herbivory impact as the ratio between herbivory rate and leaf production rate. Herbivory rates averaged 2.1% per month, did not correlate with leaf production rate, and were similar across habitats. Relative herbivore impacts exceeded leaf production rates for most species. Leaf production rate averaged 2.8%, was significantly higher in seasonally flooded forests than the other two habitats, and exhibited significant correlations with specific leaf area. Species with high herbivory rates exhibited significantly lower relative abundances in terra firme forests. Overall, focal species within lineages present contrasting patterns regarding their herbivory rates and leaf production rate within habitats. These results highlight why a lineage-based approach is necessary when attempting to connect hypotheses regarding evolutionary trade-offs to community assembly patterns.
ISSN: 0012-9658

hal-01032418
https://hal.archives-ouvertes.fr/hal-01032418

Éditeur(s) : HAL CCSD Springer
Résumé : Subduction is a major process that plays a first-order role in the dynamics of the Earth. The sinking of cold lithosphere into the mantle is thought by many authors to be the most important source of energy for plates driving forces. It also deeply modifies the thermal and chemical structure of the mantle, producing arc volcanism and is responsible for the release of most of the seismic energy on Earth. There has been considerable achievements done during the past decades regarding the complex interactions between the various processes acting in subduction zones. This volume contains a collection of contributions that were presented in June 2007 in Montpellier (France) during a conference that gave a state of the art panorama and discussed the perspectives about "Subduction Zone Geodynamics". The papers included in this special volume offer a unique multidisciplinary picture of the recent research on subduction zones geodynamics. They are organized into five main topics: Subduction zone geodynamics, Seismic tomography and anisotropy, Great subduction zone earthquakes, Seismogenic zone characterization, Continental and ridge subduction processes. Each of the 13 papers collected in the present volume is primarily concerned with one of these topics. However, it is important to highlight that papers always treat more than one topic so that all are related lighting on different aspects of the complex and fascinating subduction zones geodynamics.
https://hal.archives-ouvertes.fr/hal-00808864

ISBN : 978-3-540-87974
hal-00808864
https://hal.archives-ouvertes.fr/hal-00808864

Éditeur(s) : HAL CCSD
Résumé : International audience
Background: Everyone is subject to environmental exposures from various sources, with negative health impacts (air, water and soil contamination, noise...) or with positive effects (e.g. green space). Studies considering such complex environmental settings in a global manner are rare.Aims: We propose to use data mining techniques to create a composite exposure index with a data-driven approach, in view to assess the environmental burden experienced by populations. We illustrate this approach on a large French metropolitan area.Methods: The study was carried out in the Great Lyon area (France, 1,260,348 inhabitants in 2007, 527 km²) at the census block group (BG) scale. Indicators on NO2 annual concentrations, noise levels, proximity to green spaces and to industrial plants, and road traffic were synthetized using Multiple Factor Analysis (MFA), which allows to explore the relations between exposures and BGs without a priori knowledge, and to synthetize indicators of different types. Hierarchical clustering was then used to create BG classes. Results: The four first components of the MFA explained respectively 23, 14, 13 and 12% of the total variance. Clustering in 3 classes group: 1) BGs far from industries, greener and with less noise and air pollution than the average; 2) BGs close to industries with less green spaces and air pollution than the average; and 3)BGs far from industries but with higher levels of noise, air pollution and traffic. Greater numbers of classes were tested in order to assess a variety of clustering.Conclusions: We present a data driven approach using data mining techniques, which seem overlooked for cumulative exposure assessment in complex environmental settings. Although it cannot be applied directly for risk or health effect assessment, the resulting index can help to identify hot spots of cumulative exposure, to prioritize urban policies or to compare the environmental burden across study areas in an epidemiological framework.
Environment and Health – Bridging South, North, East and West. Conference of ISEE, ISES and ISIAQ.
Basel, Switzerland

hal-01432884
https://hal.archives-ouvertes.fr/hal-01432884
https://hal.archives-ouvertes.fr/hal-01432884/document
https://hal.archives-ouvertes.fr/hal-01432884/file/Poster_2013_ISEE_20130711.pdf

Éditeur(s) : HAL CCSD Geological Society of America
Résumé : International audience
Lakes are major depositional systems for which the related depositional processes have long been considered relatively simple. Breaking this statement, this study presents a detailed analysis of deposits in Lake Saint-Jean, the third largest natural lake in Québec. In addition to postglacial deltaic and coastal depositional systems fringing the lake, current-controlled features such as a large subaqueous prograding wedge and three sediment drifts have been identifi ed in its central portion based on two-dimensional (2-D) acoustic high-resolution subbottom profiles. The large subaqueous prograding wedge is a 4-km-long and up to 15-m-thick heterolithic shelf-like construction in the southeastern part of the lake. The three sediment drifts are 0.1–0.5-km-long and 2–5-mthick mud mounds distributed on the lake floor in the central portion of the lake. Diatom analyses and radiocarbon dating show that the development of these current-controlled features occurred during the lacustrine phase, after the disconnection with the postglacial marine Laflamme Gulf at 8.5 cal. k.y. B.P. Depositional facies show evidence of recurrent bottom-current activity. Related deposits alternate with pelagic sedimentation stages characterized by the settling of mud and biogenic accumulations. We investigated the origin of bottom currents using a numerical simulation (SYMPHONIE, an oceanographic model), with the aim of modeling wind-induced lake-scale water circulation. Simulations suggest that the subaqueous prograding wedge and the three sediment drifts result from wind-induced bottom currents generated by storm events having wind speed greater than 10 m s–1. Such strong winds are able to significantly affect sedimentation in the central portion of Lake Saint-Jean. Theresulting wind-induced sedimentary features were integrated into a refi ned lacustrine depositional model that summarizes the evolution of a group of water bodies referred to as “wind-driven water bodies.” This study applies a new tool for lake strata characterization and highlights the potential diffi cultyin differentiating them from marine deposits in the geological record.
ISSN: 0016-7606

insu-01184724
https://hal-insu.archives-ouvertes.fr/insu-01184724
DOI : 10.1130/B31145.1

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/