Éditeur(s) : Amer Geophysical Union
Résumé : Benthic foraminiferal Mg/Ca has been shown to have great potential as a proxy for reconstructing deep water temperatures. However, the exact relationship between Mg uptake in benthic foraminifera and temperature is still ambiguous, and further exploration and refinement is much needed to reduce uncertainties associated with the method. Here, we present new core-top Mg/Ca data from benthic foraminiferal species from the lower part of the thermocline in the western tropical Atlantic (northern Brazilian margin). This area is unusual in that the changes in carbonate chemistry along the transect are very small, making it an ideal region for isolating and studying the role of temperature in the incorporation of Mg into the benthic shells. Our results show that benthic foraminiferal Mg/Ca largely reflects temperature in this area. Our data are combined with previously published data to produce new and improved Mg/Ca calibration equations for a number of benthic foraminiferal species within the Atlantic Ocean. Our study provides the first C. wuellerstorfi Mg/Ca data for the 46 degrees C temperature range and indicates that C. wuellerstorfi Mg/Ca is strongly controlled by temperature. As a result, the newly established C. wuellerstorfi calibration over the entire 06 degrees C temperature range is significantly improved with respect to previously published C. wuellerstorfi calibrations limited to the coldest part between 0 and 4 degrees C. Other benthic species (Cibicidoides kullenbergi, Globocassidulina subglobosa, Uvigerina peregrina, and Oridorsalis umbonatus) have also been studied, although these results are less conclusive.
Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2013-04 , Vol. 14 , N. 4 , P. 929-946

Droits : 2013. American Geophysical Union. All Rights Reserved.
http://archimer.ifremer.fr/doc/00181/29191/27596.pdf
DOI:10.1002/ggge.20043
http://archimer.ifremer.fr/doc/00181/29191/

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 15-19 octobre 1999
Résumé : The development of the FAD gave rise to technical problems owing to their conception, their setting spot and of their utilisation. Failings generated by the unreliability of components or the uncertain repair precariousness, those can prove to be here more and more expensive with the progression of the ageing of devices and reasons of their loss. For as various domains that aerospace or the fishing deck layout, the engineering has functional analysis tools that permit to reduce conception uncertainties of systems by the mean of a hierarchical classification of function values of components. The application of one of these techniques, the FMEA, Failure Mode and Effects Analysis, to the study of reasons of FAD loss in La Reunion describes perfectly everything that this type of method can bring to the appraisal in fishing technology. This preventive analysis method assess the potential risks integrates perfectly in the mind of a precaution approach as it would agree to see to apply to the FADs and to their exploitation.Original Abstract: Le developpement des DCP a entraine l'apparition de problemes techniques, issus tant de leur conception, de leur lieu d'implantation que de leur utilisation. Defaillances generees par le manque de fiabilite des composants ou la precarite de reparations aleatoires, celles-ci peuvent s'averer de plus en plus couteuses au fur et a mesure du vieillissement des systemes et cause a terme de leur perte. Pour des domaines aussi divers que l'aerospatiale ou l'amenagement de pont de peche, l'ingenierie dispose d'outils d'analyse fonctionnelle qui, par le biais d'une hierarchisation des valeurs des fonctions de chaque element des systemes etudies, permettent de reduire les incertitudes de la conception. L'application d'une de ces techniques, l'Amdec, analyse des modes de defaillance et de criticite, a l'etude des causes des pertes de DCP a La Reunion illustre parfaitement tout ce que ce type de methode peut apporter a l'expertise en technologie des peches. Cette methode d'analyse preventive qui recense et met en evidence les risques potentiels s'integre parfaitement dans l'esprit d'une approche de precaution telle que celle qu'il conviendrait de voir appliquer aux DCP et a leur exploitation.

Droits : Ifremer
http://archimer.ifremer.fr/doc/00042/15289/12675.pdf
http://archimer.ifremer.fr/doc/00042/15289/

Éditeur(s) : HAL CCSD Royal Society of Chemistry
Résumé : International audience
Low-level water measurements of geological materials are fundamental in understanding the volatile inventories of the Earth from the mantle to crustal reservoirs. Here we describe the development of microanalytical techniques using the new SHRIMP SI ion microprobe to measure the abundances of OH− (as a proxy for water) in volcanic glass and nominally anhydrous minerals (NAMs). Samples were first analysed at the Carnegie Institute of Washington (CIW) on their Cameca ims-6f with calibrations based on previous FTIR and manometry analyses. SHRIMP SI is a large geometry ion microprobe and is currently mainly used for O and S isotope analyses. The analytical protocol used here incorporates multiple collection of 16O− and 16O1H− allowing rapid measurements. A single calibration line incorporating all glasses and NAMs for the SHRIMP SI allows calibration of 16O1H−/16O− to H2O over a wide range in concentration (50 to 15 000 ppm H2O). This calibration line has around a 10% uncertainty, which appears to be limited only by sample heterogeneity. The current background for SHRIMP analysis is between 20–40 ppm but this is expected to improve with improved pumping on the source chamber. A current limitation to water analysis of NAM samples, by any technique, is having a range of standard materials to enable OH− calibration to absolute H2O concentrations. Data are presented for 7 NAM samples (2 olivines, 2 orthopyroxenes and 3 clinopyroxenes) that appear to be promising as potential standards for international laboratory H2O measurements. These NAM samples have been analysed and characterised here by SHRIMP SI, FTIR, EMP and the Cameca ims-6f ion microprobe at CIW. Four of these samples have previously been measured by manometry to determine absolute H2O concentrations.
ISSN: 0267-9477

hal-01243514
https://hal.archives-ouvertes.fr/hal-01243514
DOI : 10.1039/c5ja00047e

Éditeur(s) : Elsevier
Résumé : Overexploitation of marine resources remains a problem worldwide. Many works advocate for the use of marine reserves as a central element of future stock management in a sustainable perspective. In the present paper, we address the influence of protected areas upon fisheries sustainability within an eco-systemic framework through a dynamic bio-economic model integrating a trophic web, catches and environmental uncertainties. The model is spatially implicit. The evaluation of the ecosystem is designed through the respect along time of constraints of both conservation and guaranteed captures. Using the mathematical concept of invariance kernel in a stochastic context, we define different MPA effects according to biodiversity catches or mixed points of view. Numerical simulations inspired from data of Abore coral reef reserve in New Caledonia illustrate the main concepts. In this case, it is pointed out how MPA conservation effect is not necessarily conflicting with MPA catches effect. it is shown that such a co-viability requires medium exploitation rate. Moreover, the climatic changes represented by rise in cyclonic events seem to reinforce these assertions. (C) 2007 Elsevier B.V. All rights reserved.
Ecological Modelling (0304-3800) (Elsevier), 2007-11 , Vol. 208 , N. 2-4 , P. 353-366

Droits : 2007 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2007/publication-3510.pdf
DOI:10.1016/j.ecolmodel.2007.06.018
http://archimer.ifremer.fr/doc/00000/3510/

Éditeur(s) : Elsevier Science Bv
Résumé : Academia and management agencies show a growing interest for ecosystem-based fishery management (EBFM). However, the way to operationalize this approach remains challenging. The present paper illustrates how the concepts of stochastic co-viability, which accounts for dynamic complexities, uncertainties, risk and sustainability constraints, can be useful for the implementation of EBFM. In the present case, this concept is used to identify fishing strategies that satisfy both ecological conservation and economic sustainability in a multi-species, multi-fleet context. Economic Viability Analysis (EVA) and the broader Co-Viability Analysis (CVA), are proposed to expand the usual Population Viability Analysis (PVA) and precautionary approach. An illustration is proposed, using data on the fisheries of Bay of Biscay (France) exploiting the stocks of nephrops and hake. Stochastic simulations show how CVA can guarantee both ecological (stock) and economic (profit) sustainability. Using 2008 as a baseline, the model is used to identify fishing efforts that ensure such co-viability. (C) 2012 Elsevier B.V. All rights reserved.
Ecological Economics (0921-8009) (Elsevier Science Bv), 2012-03 , Vol. 75 , P. 32-42

Droits : 2012 Elsevier Science Bv
http://archimer.ifremer.fr/doc/00074/18571/16153.pdf
DOI:10.1016/j.ecolecon.2012.01.005
http://archimer.ifremer.fr/doc/00074/18571/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Multiple chemicals are emitted in residential accommodation. Aggregate Daily Doses (ADD) (ng/kg-bw/d) were estimated for 32 semivolatile organic compounds (SVOCs) of different chemical families that are frequently detected in French dwellings in both air and settled dust. Daily doses were determined using steady-state models for the population, categorized into 11 age groups covering birth to age 30. Three routes of exposure were taken into account: dust ingestion, inhalation (gaseous and particulate phases) and dermal contact with the gaseous phase of air. Contamination levels were preferentially retrieved from large, nationwide representative datasets. A two-dimensional probabilistic approach was used to assess parametric uncertainty and identify the most influential factors. For children aged 2 to 3 years, ADD estimates spanned orders of magnitude, with median values ranging from 8.7 pg/kg-bw/d for 2,2′,3,4,4′-pentabromodiphenylether (BDE 85) to 1.3 μg/kg-bw/d for di-isobutyl phthalate (DiBP). Inhalation, ingestion and dermal pathway contributed at varying levels, and depending on compound, air was the dominant medium for 28 of the 32 compounds (either by inhalation or dermal contact). Indoor exposure estimate variance was mainly driven by indoor contamination variability, and secondarily by uncertainty in physical and chemical parameters. These findings lend support to the call for cumulative risk assessment of indoor SVOCs.
ISSN: 0160-4120

hal-01635777
https://hal.archives-ouvertes.fr/hal-01635777
https://hal.archives-ouvertes.fr/hal-01635777/document
https://hal.archives-ouvertes.fr/hal-01635777/file/Article_Expo_Pelletier_Manuscript%20Env%20Int%20rev2.pdf
DOI : 10.1016/j.envint.2017.08.024

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We present evidence that GPS velocity estimates of plate motions and fault slip rates agree to within uncertainties with geologic estimates during the most recent phase of the geologic evolution of the E Mediterranean region (post-Late Miocene). On this basis, we use the GPS differential velocities to estimate the timing of initiation of the principal structures in NW Turkey, the N Aegean Sea, and central Greece, including, the Marmara Sea, the Gulfs of Evia (GoE) and Corinth (GoC). and the Kephalonia Transform fault (KTF). We interpret these ages to indicate that the North Anatolian fault propagated across the N Aegean, opening the GoE and GoC and initiating the KTF, during the past 1-4 Ma. We further suggest that Aegean extension that was earlier more distributed across the Aegean Basin became focused on this new fault system allowing the southern Aegean and Peloponnisos to translate SW with little internal deformation, as observed today with GPS. This change in tectonic configuration may account for the clear geologic evidence for crustal thinning throughout the S Aegean in apparent contradiction with low present-day strain rates. We further show that the low present-day strain rate along the southern edge of the Aegean micro-plate requires substantial aseismic slip along the plate interface below Crete, consistent with the low level of historic, subduction-type earthquakes along this segment of the subduction zone.
ISSN: 0040-1951

hal-00512634
https://hal.archives-ouvertes.fr/hal-00512634
DOI : 10.1016/j.tecto.2009.05.027

Éditeur(s) : HAL CCSD
Résumé : International audience
ABSTRACT :A satellite retrieval of surface solar irradiance (SSI) based on GOES satellite data is presented and validated for the French Guiana with three years of in situ measurements from six ground stations. We propose a particle filter approach combining GOES satellite observations and in situ data. We propose an original observation function based on a joint probability distribution and taking advantages of the characteristics of both the involved type of data. The statistical results are compared with those of existing estimation methods and they are found to be in accordance with them. The daily bias ranges from -12 W/m² (-6% of the mean of measurements) to 12 W/m² (6%), depending on the stations. The daily root mean square difference ranges between 23 W/m² (10%) and 27 W/m² (15%). The correlation coefficient is close to 0.92. There is no seasonal climatic effect on the method, the bias and RMSD remain similar for both the rainy and the dry season, but better correlation is observed in the rainy season than in the dry season. Uncertainties are mainly due to the presence of specific tropical atmospheric conditions during the dry season. The method has been tested through various tests: cross-validation scheme has highlighted the potential generalization of the model in a temporal dimension; the ability of the method to effectively duplicate anomalies in surface solar irradiance time series has also been tested. The robustness of the results shows the interest of the method compared to other existing estimation methods. Because of its simplicity of implementation this method opens new prospects in estimating surface solar irradiance. It is concluded that using a particle filter and original observation function method allow a high-quality surface solar irradiance estimation in French Guiana.RESUMEUne méthode d'estimation de l'irradiance solaire de surface (SSI) à partir de données satellites GOES est présentée et validée par comparaison avec trois années de mesures in situ provenant de six stations météorologiques de Guyane Française. Dans cet article, nous proposons une approche par filtre particulaire combinant observations du satellite GOES et données in situ. Nous proposons une fonction d'observation originale basée sur une distribution de probabilité conjointe des deux types de données. Les résultats statistiques sont conformes à ceux des méthodes existantes. Le biais journalier varie de -16 W / m² (-7% de la moyenne des mesures) à 12 W / m² (6%). L'erreur quadratique moyenne (RMSD) est comprise entre 23 W / m² (10%) et 27 W / m² (15%). Le coefficient de corrélation est de 0,92. La méthode est peu sensible aux variations climatiques saisonnières, le biais et RMSD restent similaires en saison des pluies comme en saison sèche, mais une meilleure corrélation est observée pendant la saison des pluies. Les incertitudes sont principalement dues à la présence de conditions atmosphériques tropicales spécifiques en saison sèche. La méthode a été soumise à différents tests : un processus de validation croisée a mis en évidence la possible généralisation du modèle dans une dimension temporelle, la capacité du modèle à reproduire efficacement des anomalies dans les séries temporelles d'irradiance solaire de surface a aussi été testée. La robustesse des résultats obtenus montrent l'intérêt du modèle par rapport aux autres méthodes d'estimation existantes. A cause de sa simplicité de mise en oeuvre cette méthode ouvre de nouvelles perspectives en matière d'estimation de l'irradiance solaire au sol. Nous concluons que l'utilisation d'un filtre particulaire combinée à une fonction d'observation originale permet une estimation de haute qualité de l'irradiance solaire au sol en Guyane Française.
Canadian Journal of Remote Sensing

meteo-01304574
https://hal-meteofrance.archives-ouvertes.fr/meteo-01304574
DOI : 10.1080/07038992.2015.1040150

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We develop a block model for the Aegean and surrounding areas, constrained by Global Positioning System (GPS), in order to investigate the degree of coupling on the Hellenic subduction interface (i.e., the fraction of the motion across the plate boundary accommodated by elastic strain accumulation). We use previously published models, and seismicity to define the geometry of the interface separating the down-going Nubian slab from the overriding Aegean. This model provides a good fit to the GPS observations; for the ∼200,000 km2 Aegean block the wrms of the residual velocities is 1.4 mm/yr for 80 GPS velocity estimates, approximately the 95% level of the GPS velocity uncertainties. We investigate the degree of coupling on the seismically active plate interface, the Hellenic trench splay fault (believed to be the source of the 365 AD Great Crete Earthquake and Tsunami), and the Kephalonia transform fault by comparing the modeled GPS residual velocity field for a range of coupling values. The GPS observations are almost insensitive to coupling on the Kephalonia transform fault, because of the vertical dip of the fault that creates interseismic deformation only close to the fault where few GPS sites exist. The absence of resolvable shortening of the leading edge of the Aegean Plate precludes coupling of more than 0.2 (20% of the full Nubia-Aegean convergence rate) on the modeled plate interface. Because of the shallow dip of the plate interface and trench splay fault, and high rate of convergence, if these boundaries were fully coupled, high elastic strain rates would be expected to extend well into the overriding Aegean plate. Based on our preferred value for the degree of coupling (0.1), and assuming characteristic earthquake behavior, we estimate a recurrence time for great earthquakes with slip similar to that for the 365 Crete event of 5700-8300 yr, consistent with the absence of subsequent great earthquakes on this segment of the subduction zone.
ISSN: 0012-821X

hal-01053486
https://hal.archives-ouvertes.fr/hal-01053486
DOI : 10.1016/j.epsl.2013.10.018

Éditeur(s) : HAL CCSD Réseau « Développement durable et territoires fragiles »
Résumé : The Green and Blue infrastructure (Trame verte et bleue –TVB) is a new conservation policy tool based on the notions of ecological network and corridor. The introduction of this new instrument through the French Grenelle environment commitments brings about some change in the spatial strategy of the conservation policy. Beyond the identification of priority conservation areas, ecological planning of all the territory is concerned. The TVB’s implementation process establishes the connection of multi and nested decisional and action levels. It thus creates specific situations of complexity and uncertainty that require innovation and perpetual change of governance. The study of the Auvergne region case through the adaptive governance analytical framework highlights the potential fruitful role of Regional nature parks in such dynamics of change and learning. Mots-clés : aménagement durable des territoires, biodiversité, réseau écologique, corridor écologique, gouvernance adaptative, socio-écosystème, trame verte et bleue Keywords : Sustainable landplaning, Biodiversity, Ecological network, Adaptive governance, socio-ecosystem
La Trame verte et bleue (TVB), nouveau dispositif d’action publique visant à enrayer la perte de biodiversité traduit un renouvellement des référentiels de justification des politiques de conservation et de leur stratégie territoriale. Il s’agit d’intégrer la planification écologique dans l’aménagement de l’ensemble du territoire. Le processus de territorialisation de la TVB met en rapport de multiples niveaux de décision et d’action imbriqués. Il crée de ce fait des configurations inédites de complexité et d’incertitude et implique des innovations en termes de gouvernance que le cadre analytique de la gouvernance adaptative permet d’appréhender. En nous appuyant sur l’exemple du Parc Naturel Régional des Volcans d’Auvergne, nous analysons le rôle que ces institutions sont susceptibles de jouer dans ces dynamiques de changement et d’apprentissage socio-technique et politique qui conditionnent une mise en œuvre effective de la TVB.
ISSN: 1772-9971

hal-01195370
https://hal.archives-ouvertes.fr/hal-01195370
DOI : 10.4000/developpementdurable.9675
PRODINRA : 269288

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The natural river water certified reference material SLRS-5 (NRC-CNRC) was routinely analysed in this study for major and trace elements by ten French laboratories. Most of the measurements were made using ICP-MS. Because no certified values are assigned by NRC-CNRC for silicon and 35 trace element concentrations (rare earth elements, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y and Zr), or for isotopic ratios, we provide a compilation of the concentrations and related uncertainties obtained by the participating laboratories. Strontium isotopic ratios are also given. Le matériau de référence certifié d'eau de rivière naturelle SLRS-5 (NRC-CNRC) est analysé régulièrement comme contrôle qualité par dix laboratoires français étudiant les éléments majeurs et en trace dans les solutions naturelles. La plupart des mesures sont réalisées par ICP-MS. Le silicium et 35 éléments en trace (terres rares, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y et Zr) ne sont pas certifiés par NRC-CNRC. Aucun rapport isotopique n'est disponible. Nous proposons, pour ces éléments, des valeurs moyennes et leurs incertitudes associées obtenues par les différents laboratoires participants. Le rapport isotopique de Sr est aussi mesuré.
ISSN: 1639-4488

hal-00906166
https://hal.archives-ouvertes.fr/hal-00906166
DOI : 10.1111/j.1751-908X.2013.00232.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
A new portable sampling system was developed to extract Radium isotopes from large volumes (up to 300 L) of fresh surface- and ground-waters of low Ra-activities (<5 mBq/L). Ra is quantitatively adsorbed on a small amount (6.5 g) of MnO2-coated acrylic fibers, which are then dried and burned at 600 °C in the laboratory. The resulting Mn-oxide powder (about 2 cm3 when compacted) is then analyzed through gamma-ray spectrometry which allows measurement of the whole Ra quartet (226Ra, 228Ra, 224Ra and 223Ra) in a single counting of a few days. The usual relative standard combined uncertainties (1σ) are 2–3% for 226Ra, 228Ra and 224Ra; and less than 10% for 223Ra. This method was applied to the analysis of Ra in karstic waters of the Lez aquifer, and surface- and ground-waters of the upper and middle Vidourle watershed (South of France). The analyzed waters have relatively low 226Ra activities (1–4 mBq/L) in both cases, regardless of the contrasted geology (Mesozoic limestone vs crystalline Variscan basement), but clearly distinct (228Ra/226Ra) ratios in agreement with the differences in Th/U ratios of the two drained areas. Short-lived Ra isotopes (224Ra and 223Ra) appear to be mainly influenced by near-surface desorption/recoil processes for most of the sampling sites.
ISSN: 0969-8043

hal-01491281
https://hal.archives-ouvertes.fr/hal-01491281
DOI : 10.1016/j.apradiso.2016.12.010

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Imaging deep active volcanic areas remains a challenge in our understanding of their activity and evolution, especially in subduction zones. Study of magnetic anomalies is appropriate to access such dynamics in depth. The magnetic anomaly pattern of the Lesser Antilles Arc (LAA) subduction is studied through Curie Point Depth (CPD), interpreted as the depth of the 580 °C isotherm, and developed to better assess the deep thermal structure of the arc. The depth of the estimated CPD exhibits a complex topography. Keeping in mind the overall uncertainty associated with this method, a main doming is evidenced below the Guadeloupe archipelago. Its apex is shifted towards the ancient arc, suggesting a very hot state of the fore-arc/arc domain. To better understand the LAA thermal state, we perform 2D thermo-mechanical simulations of the subduction zone. Recalling that magnetite is a serpentinization by-product, we simulate water transfer triggered by slab dehydration to test the assumption of fore-arc serpentinization suggested by the positive magnetic anomaly in the vicinity of the Guadeloupe archipelago. In this area, the subduction-induced arc lithosphere hydration and related weakening trigger a fast heating of the upper plate by basal convective removal. This process of fast arc lithosphere thinning may apply where simultaneously the volcanic arc is split in two and normal convergence is high enough. As serpentinization strongly decreases P-wave velocity, we propose a new interpretation of a published seismic profile below Guadeloupe. The seismic layer previously interpreted as the arc lower crust may rather be a layer of serpentinized mantle, as supported by spatial correlations between gravimetric and magnetic anomalies. Consequently, at the scale of Guadeloupe Island, the fore-arc Moho would be shallower than initially assumed, with a dome shape more consistent with both the extensive deformation active since the Oligocene in the inner fore-arc and the CPD doming.
ISSN: 0040-1951

Droits : http://creativecommons.org/licenses/by-nc-nd/
insu-01505300
https://hal-insu.archives-ouvertes.fr/insu-01505300
https://hal-insu.archives-ouvertes.fr/insu-01505300/document
https://hal-insu.archives-ouvertes.fr/insu-01505300/file/Gailler-2017.pdf
DOI : 10.1016/j.tecto.2017.03.014

Éditeur(s) : HAL CCSD
Résumé : Tropical forests are a biodiversity hotspot, with the coexistence of numerous species until a fine spatial scale. Particularly, 16.000 tree species coexist in Amazonia, 1.800 in Frenche Guiana and between 120 and more than 200 tree species per hectare. However, there are some uncertainties in maintaining diversity in regard to global changes. Hence before predicting the diversity evolution face of global changes, fundamental studies are needed to understand which assembly processes are involved in the maintenance of diversity. These fundamental studies still relevant given the lack of consensus on the relative importance of assembly processes. This thesis is a continuation of these fundamental studies, using innovative integrative approach, at multi-scale, to address three types of diversity: taxonomic diversity, functional and phylogenetic. Our results challenge the importance of environmental filtering for hydrological and chemical properties of soils, versus the importance of biotic interactions on community assembly. Furthermore, our results suggest that species distributions could be affected by forest dynamics related to falling trees and therefore by light availability. Finally, we have highlighted the importance of dispersal limitation on community assembly.
Les forêts tropicales représentent un ‘hotspot’ de diversité avec un nombre considérable d’espèces qui coexistent jusqu’à une échelle locale fine. Plus particulièrement, 16 000 espèces d’arbres coexistent en Amazonie, 1 800 en Guyane française et entre 120 et plus de 200 espèces d’arbres par hectare. Cependant, le maintien de cette diversité face aux changements globaux actuels et à venir (qu’ils soient anthropiques ou climatiques…) est incertain. Avant de pouvoir prédire l’évolution de la diversité face aux changements globaux, un travail fondamental est nécessaire afin de comprendre les processus d’assemblage des communautés, processus qui maintiennent cette diversité. Ce travail est réalisé depuis de nombreuses années en écologie et reste d’actualité vu l’absence de consensus quant à l’importance relative des processus d’assemblage. Cette thèse s’inscrit dans la continuité de ce travail fondamental en utilisant une approche intégrative innovante, qui aborde de manière multi-échelle trois types de diversité : diversité taxonomique, fonctionnelle et phylogénétique. Nos résultats questionnent sur l'importance du filtrage environnemental quant aux propriétés hydrologiques et chimiques des sols, et sur celle des interactions biotiques dans l’assemblage de la communauté étudiée. Par ailleurs, nos résultats suggèrent que les distributions d’espèces puissent être influencées par la dynamique forestière en lien avec les chutes d’arbres et donc avec la disponibilité en lumière. Enfin, nous avons mis en évidence l’importance de la limitation de dispersion.
https://tel.archives-ouvertes.fr/tel-01418447

NNT : 2016YANE0003
tel-01418447
https://tel.archives-ouvertes.fr/tel-01418447
https://tel.archives-ouvertes.fr/tel-01418447/document
https://tel.archives-ouvertes.fr/tel-01418447/file/these.pdf

Résumé : After 12 years of a difficult start, the sea bass (Dicentrarchus labrax) breeding projects are multiplying. Faced with the constraints presented by the sites used in the past, farming at sea seems to offer conditions more conducive to the growth and survival of the animals. The zootechnical data from the farm makes it possible to link the rate of growth and the thermal profile of the site. Risks and uncertainties still weigh heavily on aquafarming projects, but solutions such as insurance are helping to improve their economic feasibility. The economic and financial analysis comes up with good overall profitability of the project, even if the duration of the breeding cycle and the necessity to ensure a progressive increase in operating capacity make the start-up phase long and not very lucrative.
(OCR non controlé) Après 12 années d'un démarrage difficile, les projets d'élevage du loup (Dicentrarchus labrax) se multiplient. Face aux contraintes que présentent les sites utilisés par le passé, l'élevage en mer semble offrir des conditions plus favorables à la croissance et à la survie des animaux. Les données zootechniques de l'élevage permettent de mettre en relation la vitesse de croissance et le profil thermique du site. Risques et incertitudes pèsent encore lourdement sur les projets aquacoles, mais des solutions telles que l'assurance contribuent à améliorer leur faisabilité économique. L'analyse économique et financière conclut à une bonne rentabilité globale du projet même si la durée du cycle d'élevage et la nécessité d'assurer une montée en puissance progressive de l'exploitation rendent la phase de démarrage longue et peu rémunératrice.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1989/rapport-2417.pdf
http://archimer.ifremer.fr/doc/00000/2417/

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
The exchanges of carbon, water and energy between the atmosphere and the Amazon basin have global implications for the current and future climate. Here, the global atmospheric inversion system of the Monitoring of Atmospheric Composition and Climate (MACC) service is used to study the seasonal and interannual variations of biogenic CO 2 fluxes in Amazonia during the period 2002–2010. The system assimilated surface measurements of atmospheric CO 2 mole fractions made at more than 100 sites over the globe into an atmospheric transport model. The present study adds measurements from four surface stations located in tropical South America, a region poorly covered by CO 2 observations. The estimates of net ecosystem exchange (NEE) optimized by the inversion are compared to an independent estimate of NEE upscaled from eddy-covariance flux measurements in Amazonia. They are also qualitatively evaluated against reports on the seasonal and interannual variations of the land sink in South America from the scientific literature. We attempt at assessing the impact on NEE of the strong droughts in 2005 and 2010 (due to severe and longer-than-usual dry seasons) and the extreme rainfall conditions registered in 2009. The spatial variations of the seasonal and in-terannual variability of optimized NEE are also investigated. While the inversion supports the assumption of strong spatial heterogeneity of these variations, the results reveal critical limitations of the coarse-resolution transport model, the surface observation network in South America during the recent years and the present knowledge of modelling uncertainties in South America that prevent our inversion from capturing the seasonal patterns of fluxes across Amazonia. However, some patterns from the inversion seem consistent with the anomaly of moisture conditions in 2009.
ISSN: 1680-7316

hal-01557375
https://hal.univ-lorraine.fr/hal-01557375
https://hal.univ-lorraine.fr/hal-01557375/document
https://hal.univ-lorraine.fr/hal-01557375/file/acp-15-8423-2015.pdf
DOI : 10.5194/acp-15-8423-2015-supplement

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Recent research has demonstrated the importance of dermal exposure for some semivolatile organic compounds (SVOCs) present in the gas phase of indoor air. Though models for estimating dermal intake from gaseous SVOCs exist, their predictions can be subject to variations in input parameters, which can lead to large variation in exposure estimations. In this sensitivity analysis for a steady state model, we aimed to assess these variations and their determinants using probabilistic Monte Carlo sampling for 8 SVOCs from different chemical families: phthalates, bisphenols, polycyclic aromatic hydrocarbons (PAHs), organophosphorus (OPs), organochlorines (OCs), synthetic musks, polychlorinated biphenyls (PCBs) and polybromodiphenylethers (PBDEs). Indoor SVOC concentrations were found to be the most influential parameters. Both Henry's law constant (H) and octanol/water partition coefficient (Kow) uncertainty also had significant influence. While exposure media properties such as volume fraction of organic matter in the particle phase (fom-part), particle density (ρpart), concentration ([TSP]) and transport coefficient (ɣd) had a slight influence for some compounds, human parameters such as body weight (W), body surface area (A) and daily exposure (t) make a marginal or null contribution to the variance of dermal intake for a given age group. Inclusion of a parameter sensitivity analysis appears essential to reporting uncertainties in dermal exposure assessment.
ISSN: 0160-4120

hal-01526430
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01526430
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01526430/file/Dermal%20absorption%20of%20semivolatile%20organic%20compounds_accepted.pdf
DOI : 10.1016/j.envint.2017.02.005
PUBMED : 28249739

Éditeur(s) : HAL CCSD John Libbey Eurotext
Résumé : International audience
Chemical risk assessment is a tool used in decision-making processes concerning situations of scientific uncertainty. Approaches to risk assessment in occupational and environmental health share the same objective of risk prevention. Nevertheless, the methods for both differ depending on whether the goal is to enforce regulations or conduct expert assessments and studies. These differences are stronger in occupational health, for which regulations require risk assessments at the work station, to classify and prioritize exposure situations to implement occupational risk prevention strategies. Risk assessment thus has somewhat different meanings in occupational and environmental health. This article attempts to clarify the different terms used in the different contexts and to describe the similarities and differences of the two approaches.
ISSN: 1635-0421

hal-00936256
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00936256
DOI : 10.1684/ers.2013.0646

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : This paper develops a comparative overview of the development of Fish Aggregating Devices (or fads) by the tropical purse seine fisheries in various ocean areas (Atlantic, Indian, Western and Eastern Pacific Oceans). First, a comparative review of fishery statistics is developed. Recent catches on fads by purse seiners can be estimated at a level of one million tons yearly. This comparison allows to describe the fishing zones and catch trends over time, the species composition and size taken in the various fad fisheries. Skipjack tuna is the dominant species in most fad fisheries, but significant amounts of yellowfin and bigeye are also frequently taken under fads. The paper also presents an overview of various observer data concerning the by-catches of the various fisheries using fads. This comparison allows to estimate the total worldwide yearly by-catches at about 100,000 t, and their species composition in each ocean. The fad technology used in the various oceans by purse seiners is described. The recent use of fads by purse seiners has introduced major uncertainties in most stock assessments, because analyses are hampered by changes in the fishing effort in a fad fishery, by changes in fishing zones and in sizes caught. As a last point, the management of fads presently done or in view by the various tuna bodies are introduced. It appears that the present massive use of fads worldwide is perhaps an unsafe fishing mode, which could produce serious overfishing of many stocks. There is then a consensus that the use of fads needs to be controlled and limited to sustainable biological levels.

Droits : Ifremer
http://archimer.ifremer.fr/doc/00042/15278/12664.pdf
http://archimer.ifremer.fr/doc/00042/15278/

Éditeur(s) : Amer Meteorological Soc
Résumé : Salinity measurements from 119 surface drifters in 2007-12 were assessed; 80% [Surface Velocity Program with a barometer with a salinity sensor (SVP-BS)] and 75% [SVP with salinity (SVP-S)] of the salinity data were found to be usable, after editing out some spikes. Sudden salinity jumps are found in drifter salinity records that are not always associated with temperature jumps, in particular in the wet tropics. A method is proposed to decide whether and how to correct those jumps, and the uncertainty in the correction applied. Northeast of South America, in a region influenced by the Amazon plume and fresh coastal water, drifter salinity is very variable, but a comparison with data from the Soil Moisture and Ocean Salinity satellite suggests that this variability is usually reasonable. The drifter salinity accuracy is then explored based on comparisons with data from Argo floats and from thermosalinographs (TSGs) of ships of opportunity. SVP-S/SVP-BS drifter records do not usually present significant biases within the first 6 months, but afterward biases sometimes need to be corrected (altogether, 16% of the SVP-BS records). Biases start earlier after 3 months for drifters not protected by antifouling paint. For the few drifters for which large corrections were applied to portions of the record, the accuracy cannot be proven to be better than 0.1 psu, and it cannot be proven to be better than 0.5 psu for data in the largest variability area off northeast South America. Elsewhere, after excluding portions of the records with suspicious salinity jumps or when large corrections were applied, the comparisons rule out average biases in individual drifter salinity record larger than 0.02 psu (midlatitudes) and 0.05 psu (tropics).
Journal Of Atmospheric And Oceanic Technology (0739-0572) (Amer Meteorological Soc), 2014-04 , Vol. 31 , N. 4 , P. 967-983

Droits : 2014 American Meteorological Society
http://archimer.ifremer.fr/doc/00190/30095/28748.pdf
DOI:10.1175/JTECH-D-13-00158.1
http://archimer.ifremer.fr/doc/00190/30095/