Éditeur(s) : Elsevier Science Bv
Résumé : Small-scale fisheries have traditionally received less research effort than large-scale fisheries and are generally under-studied in Europe. In spite of their comparatively low volume of catches and economic importance, small-scale fisheries are socially important and an integral part of the European coastal zone. Considering the high heterogeneity of situations and the paucity of quantitative data, we used an analytical methodology based on the comparative method. We carried out an analysis of small-scale fisheries (SSFs) in Europe based on a selection of nine case studies. Our objective was to obtain a comprehensive description of small-scale fleets covering different areas/fisheries/species, encompassing the diversity and specific conditions under which SSFs operate, in order to demonstrate the ecological and social sustainability of this often overlooked fisheries segment. A common approach formulated so that the case studies could be compared with the case histories of other competing users, required that for each set of criteria – technical, biological, socio-economic, and institutional – a set of relevant items and indicators was established. An analysis of characteristics common to the selected case studies is conducted and an attempt made to extend our comparisons to the whole of the European Union. Our results show that (as compared with large-scale fleets, their main competitor) small-scale fleets: (i) are composed of smaller vessels and, consequently, travel lower distances to fishing grounds, and are more reliant on coastal areas; (ii) have smaller crews (although the global employment figure is similar to that of large-scale fleets in Europe); (iii) use mostly, but not exclusively, passive gears; (iv) use multi-purpose fishing approaches, and can change the fish species they target during the year; (v) have lower extraction rates; (vi) have lower total capital investments (including fishing rights), turnover and costs; and (vii) have lower fuel consumption, making them less sensitive to changing oil prices. Dependence on subsidies is lower (viii). Involvement in fisheries management is variable, conservation and access regulation measures are largely local in origin. For the selected case studies, the most significant competitors are large-scale fleets, and recreational fisheries, but other sources of interaction (water quality, invasive species, etc.) cannot be ignored.
Fisheries Research (0165-7836) (Elsevier Science Bv), 2013-02 , Vol. 140 , P. 1-13

Droits : 2012 Elsevier B.V. All rights reserved
http://archimer.ifremer.fr/doc/00118/22934/20757.pdf
DOI:10.1016/j.fishres.2012.11.008
http://archimer.ifremer.fr/doc/00118/22934/

Résumé : Les mécanismes à l’origine du maintien de la forte diversité locale des arbres des forêts tropicales humides constituent encore une énigme pour les scientifiques. Cette thèse a pour but d’étudier et de comprendre certains facteurs biotiques et abiotiques qui influencent l’assemblage des communautés des forêts tropicales humides d’Amazonie. A l’aide d’une approche empirique conduite dans les forêts tropicales de Guyane française et du Loreto au Pérou, de nombreuses expériences de terrain ont été mises en place dans le but d’apporter des éléments de réponse sur les mécanismes impliqués dans le maintien de la diversité des communautés d’arbres et d’insectes des forêts amazoniennes. Dans un premier temps, cette thèse permet de souligner l’importance des pressions biotiques exercées sur les communautés d’arbres. En effet, les communautés d’insectes peuvent influencer la composition des communautés d’arbres le long d’un gradient environnemental conduisant à des compromis entre la défense et la croissance. Ces compromis ou tradeoff permettent de maintenir la coexistence des espèces de forêts tropicales humides en favorisant la spécialisation des arbres à leur habitat (Chapitre 1, Annexe 3). Cependant, de nombreux facteurs peuvent engendrer des variations dans les compromis d’allocation exhibés par les plantes, ce qui peut compliquer la validité de ces résultats. Dans ce sens, nous avons souligné l’influence du rôle de la cascade trophique et l’existence chez certaines espèces d’arbres de stratégies d’évitement des insectes (Chapitre 2). Dans un second temps, nous avons montré que les filtres environnementaux et les distances géographiques favorisent un fort turnover de la composition des arthropodes des forêts tropicales (chapitre 3, Annexe 2). Les résultats de cette étude ont des implications fondamentales sur les mécanismes qui expliquent la structuration des communautés d’insectes herbivores. Nous avons souligné l’importance de l’interaction des communautés des insectes herbivores et de leurs plantes associées. De plus, des prédictions sont présentées sur le degré de spécialisation des insectes à leur plante-hôte (Annexe 3), notamment sur les implications possibles dans les compromis d’allocation chez les plantes. Finalement, des perspectives de recherche sont proposées en vue de poursuivre ces travaux de recherche, et notamment des extensions de mes expériences vers d’autres régions tropicales et tempérées et l’intégration de la phylogénie pour comprendre des mécanismes de coévolution entre communautés d’arbres et insectes. Nous proposons également une intégration des résultats de cette thèse dans les stratégies locales et régionales de conservation des forêts tropicales du bassin amazonien.
The mechanisms underlying the maintenance of local diversity of trees in tropical rainforests remain under debate. This dissertation aims to study and understand some biotic and abiotic factors that may influence both tree and insect community assembly in lowland tropical forests of Amazonia. I used an empirical approach to study communities of trees and insects in tropical forests of French Guiana and Peru, to address the extent to which insect herbivores contribute to the turnover of tree species across strong environmental gradients. In Chapter 1, I studied how herbivorous insect communities can influence the composition of tree communities along an environmental gradient by reinforcing tradeoffs between defense and growth that promote habitat specialization (Chapter 1, Appendix 3). The complicated variation in the patterns of growth and defense from this study led me to pursue further observations of an alternative plant defense strategy of time-avoidance of herbivores, which I examined in detail in Chapter 2. I found evidence for coordinated leaf production in some tree species that was consistent with the satiation of herbivores, suggesting that multiple interactions between plants and their herbivores may be responsible for patterns of habitat specialization in trees. In the second part of the dissertation, I examined insect herbivore communities in detail to test for turnover in species composition across geographic and environmental gradients. In Chapter 3, I present evidence for substantial beta-diversity in arthropod communities throughout lowland Amazonian forests. In the discussion I propose research perspectives to complete this research, including the extension of observations to compare tropical and temperate regions and the integration of molecular phylogenetics information to study coevolution of plant lineages and their insect herbivores. I conclude with suggestions for the integration of the results of this thesis in local and regional strategies for the preservation and conservation of tropical forests in the Amazon basin.

http://www.theses.fr/2013AGUY0582/document

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
Context : Functional - structural models (FSM) of tree growth have great potential in forestry, but their development, calibration and validation are hampered by the difficulty of collecting experimental data at organ scale for adult trees. Due to their simple architecture and morphological properties, " model plants " such as Cecropia sciadophylla are of great interest to validate new models and methodologies, since exhaustive descriptions of their plant structure and mass partitioning can be gathered. * Aims : Our objective was to develop a model-based approach to analysing the influence of environmental conditions on the dynamics of trophic competition within C. sciadophylla trees. * Methods : We defined an integrated environmental factor that includes meteorological medium-frequency variations and a relative index representing the local site conditions for each plant. This index is estimated based on model inversion of the GreenLab FSM using data from 11 trees for model calibration and 7 trees for model evaluation. * Results : The resulting model explained the dynamics of biomass allocation to different organs during the plant growth, according to the environmental pressure they experienced. * Perspectives : By linking the integrated environmental factor to a competition index, an extension of the model to the population level could be considered.
ISSN: 1286-4560

hal-00780347
https://hal-ecp.archives-ouvertes.fr/hal-00780347
https://hal-ecp.archives-ouvertes.fr/hal-00780347/document
https://hal-ecp.archives-ouvertes.fr/hal-00780347/file/Letort2011AFS.pdf
DOI : 10.1007/s13595-011-0131-x

Éditeur(s) : HAL CCSD
Résumé : Over the last decade, distance-based methods have been introduced and then improved in the field of spatial economics to gauge the geographic concentration of activities. There is a growing literature on this theme including new tools, discussions on their specific properties and various applications. However, there is currently no typology of distance-based methods. This paper fills that gap. The proposed classification helps understand all the properties of distance-based methods and proves that they are variations on the same framework.
https://halshs.archives-ouvertes.fr/halshs-00679993

halshs-00679993
https://halshs.archives-ouvertes.fr/halshs-00679993
https://halshs.archives-ouvertes.fr/halshs-00679993v5/document
https://halshs.archives-ouvertes.fr/halshs-00679993/file/MARCON-PUECH-Hal%2000679993v5.pdf

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: Overweight in Guadeloupe is a public health matter affecting children and adults. In the present study we evaluated the metabolic profile, including serum ghrelin, leptin and adiponectin levels, in normal weight, overweight and obese school children and we analyzed the potential changes in anthropometric and metabolic risk factors after a 1-year lifestyle intervention program. Methods: Parameters were assessed at baseline and at 1 year. Three groups (G) were defined according the International Obesity Task Force reference values, G1: normal weight / G2: overweight / G3: obese. The lifestyle intervention included dietary counseling, regular physical activity and family support. Results: A total of 120 children (G1: n = 44, G2: n = 39, G3: n = 37), aged 11– 15 years and 59 % girls were enrolled. Obese children showed significant lower HDL-C, adiponectin and ghrelin concentrations, higher triglycerides, fasting blood glucose, insulin and leptin levels and also higher frequencies of abdominal obesity (G1: 2.3 %, G2: 28.2 %, G3: 73 %) and insulin resistance (GI: 39 %, G2: 72 %, G3: 89 %) than the other groups. In the overall sample, the linear regressions exploring the associations of ghrelin, adiponectin and leptin with age, gender, BMI z-score, HOMA-IR and tanner stage as independent variables showed strong associations of leptin levels with weight status and insulin resistance at baseline. The models accounted for 58 % of variability in leptin levels compared with 26 and 15 % for adiponectin and ghrelin levels respectively. In 83 children who completed the program, significant decreases in BMI z-score in overweight and obese children were noted. Leptin levels decreased significantly only in the obese group whereas adiponectin concentrations increased significantly in the three groups, In obese children, a significant correlation was found between changes in BMI Z-score, and changes in leptin levels (r = 0.39; P = 0.049) but not with changes in adiponectin levels. Conclusions: Abdominal obesity and insulin resistance were highly prevalent in obese children highlighting their risk of metabolic complications in adulthood. A 1-year long lifestyle intervention was associated with improvement in BMI z-score and metabolic parameters.
ISSN: 1743-7075

Droits : http://creativecommons.org/licenses/by/
hal-01231394
http://hal.upmc.fr/hal-01231394
http://hal.upmc.fr/hal-01231394/document
http://hal.upmc.fr/hal-01231394/file/art_10.1186_s12986-015-0039-9.pdf
DOI : 10.1186/s12986-015-0039-9

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The life-history traits and population dynamics of species are increasingly being attributed to the characteristics of their preferred habitats. While coral reef fish are often strongly associated with particular habitats, long-term studies establishing the demographic and life-history consequences of occupying different reef substrata are rare and no studies have monitored individuals in situ over their lifetime and determined the fate of their offspring. Here, we documented a quasi-turnover and local reproductive success for an entire population of orange clownfish (Amphiprion percula) from Kimbe Island, Papua New Guinea, by taking bi-annual samples of DNA over a 10-yr period (2003–2013). We compared demographic and life-history traits of individuals living on two host anemone species, Heteractis magnifica and Stichodactyla gigantea, including female size, adult continued presence (a proxy for relative longevity range), early post-settlement growth, the number of eggs per clutch and ‘local’ reproductive success (defined for each adult as the number of offspring returning to the natal population). Our results indicate that while the relative longevity of adults was similar on both host anemone species, females living in H. magnifica were larger than females in S. gigantea. However, despite females growing larger and producing more eggs on H. magnifica, we found that local reproductive success was significantly higher for clownfish living in S. gigantea. Life-history traits also exhibited local spatial variation, with higher local reproductive success recorded for adults living on S. gigantea on the eastern side of the island. Our findings support a ‘silver-spoon’ hypothesis that predicts individuals that are fortunate enough to recruit into good habitat and location will be rewarded with higher long-term reproductive success and will make a disproportionate contribution to population renewal.
ISSN: 0722-4028

hal-01357939
https://hal-univ-perp.archives-ouvertes.fr/hal-01357939
DOI : 10.1007/s00338-016-1485-1

Éditeur(s) : HAL CCSD National Institute of Environmental Health Sciences
Résumé : International audience
Safe drinking water is essential for well-being. Although microbiological contamination remains the largest cause of water-related morbidity and mortality globally, chemicals in water supplies may also cause disease, and evidence of the human health consequences is limited or lacking for many of them. We aimed to summarize the state of knowledge, identify gaps in understanding, and provide recommendations for epidemiological research relating to chemicals occurring in drinking water. Assessing exposure and the health consequences of chemicals in drinking water is challenging. Exposures are typically at low concentrations, measurements in water are frequently insufficient, chemicals are present in mixtures, exposure periods are usually long, multiple exposure routes may be involved, and valid biomarkers reflecting the relevant exposure period are scarce. In addition, the magnitude of the relative risks tends to be small. Research should include well-designed epidemiological studies covering regions with contrasting contaminant levels and sufficient sample size; comprehensive evaluation of contaminant occurrence in combination with bioassays integrating the effect of complex mixtures; sufficient numbers of measurements in water to evaluate geographical and temporal variability; detailed information on personal habits resulting in exposure (e.g., ingestion, showering, swimming, diet); collection of biological samples to measure relevant biomarkers; and advanced statistical models to estimate exposure and relative risks, considering methods to address measurement error. Last, the incorporation of molecular markers of early biological effects and genetic susceptibility is essential to understand the mechanisms of action. There is a particular knowledge gap and need to evaluate human exposure and the risks of a wide range of emerging contaminants.
ISSN: 0091-6765

hal-01118530
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01118530
PUBMED : 24380896
DOI : 10.1289/ehp.1206229
PUBMEDCENTRAL : PMC3948022

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
The issue of drinking water quality compliance in small and medium scale water services is of paramount importance in relation to the 98/83/CE European Drinking Water Directive (DWD). Additionally, concerns are being expressed over the implementation of the DWD with respect to possible impacts on water quality from forecast changes in European climate with global warming and further anticipated reductions in north European acid emissions. Consequently, we have developed a decision support system (DSS) named ARTEM-WQ (AwaReness Tool for the Evaluation and Mitigation of drinking Water Quality issues resulting from environmental changes) to support decision making by small and medium plant operators and other water stakeholders. ARTEM-WQ is based on a sequential risk analysis approach that includes consideration of catchment characteristics, climatic conditions and treatment operations. It provides a holistic evaluation of the water system, while also assessing human health risks of organic contaminants potentially present in treated waters (steroids, pharmaceuticals, pesticides, bisphenol-a, polychlorobiphenyls, polycyclic aromatic hydrocarbons, petrochemical hydrocarbons and disinfection by-products; n = 109). Moreover, the system provides recommendations for improvement while supporting decision making in its widest context. The tool has been tested on various European catchments and shows a promising potential to inform water managers of risks and appropriate mitigative actions. Further improvements should include toxicological knowledge advancement, environmental background pollutant concentrations and the assessment of the impact of distribution systems on water quality variation.
ISSN: 1660-4601

hal-01122233
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122233
PUBMED : 25046634
DOI : 10.3390/ijerph110707354
PUBMEDCENTRAL : PMC4113881

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 Public Library of Science
Résumé : International audience
The seasonal patterns of conceptions and births differ between geographic areas. Several potential determinants of this variation have been identified, including biological, environmental and behavioral elements, but festive events are rarely mentioned. We investigated the possible association between the carnival and seasonal fertility variations in the French West Indies. We ran a retrospective registry-based study. The data were extracted from the registry of all births on Guadeloupe between 2000 and 2011 (n = 74,412), and from the Maternity Birth Register of the University Hospital, for all pregnancies of at least 14 completed weeks of gestation (observable conceptions) with an outcome recorded between 2007 and 2010 (n = 8,425). We compared data during and outside the carnival period for each year, including 2009, when there was no carnival due to a 44-day general strike. In all years other than 2009, the weekly number of births was higher for pregnancies initiated during the carnival period than for pregnancies initiated at other times, and the weekly number of observable conceptions was higher during the carnival period than at other times. Our findings support the hypothesis that carnivals in the French West Indies are associated with an increase in the number of conceptions and subsequent births.
ISSN: 1932-6203

hal-01485778
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01485778
DOI : 10.1371/journal.pone.0173102
PUBMED : 28253323

Éditeur(s) : HAL CCSD AGU and the Geochemical Society
Résumé : International audience
The transition between the small melt lens observed on top of fast spreading ridge magma chambers and the overlying sheeted dike complex marks the interface between magma and the hydrothermal convective system. It is therefore critical to our understanding of fast spreading ridge accretion processes. We present maps of two areas of the Oman ophiolite where this transition zone is observed as continuous outcrops. Our observations, which include the base of the sheeted dike being crosscut by gabbros, are consistent with episodic dike injections in a steady state model but also suggest that the root of these dikes is commonly erased by vertical movements of the top of the melt lens. Dike assimilation is a possible mechanism for incorporating hydrated phases, which result from hydrothermal alteration, to the melt lens during upward migrations of its upper boundary. Upward migrations are also responsible for a granoblastic overprint of the root of the dikes that is also observed in the stoped diabase xenoliths. This granoblastic overprint attests to reheating of previously hydrothermally altered lithologies which can even trigger hydrous partial melting due to the lowering of the solidus of mafic lithologies by the presence of a water activity. Clinopyroxenes present in these granoblastic lithologies are typically low in Ti and Al content, thus strongly contrasting with corresponding magmatic clinopyroxene. This may attest to the recrystallization of clinopyroxenes after amphiboles under the peculiar conditions present at the root zone of the sheeted dike complex. Downward migrations of the top of the melt lens result in the crystallization of the isotropic gabbros at its roof, which represent the partly fossilized melt lens. Melt lens fossilization eventually occurs when magma supply is stopped or at the melt lens margins where the thermal conditions become cooler. Melt lens migration, recrystallization of hydrothermally altered sheeted dikes during reheating stages, and assimilation processes observed in the Oman ophiolite are consistent with the observations made in IODP Hole 1256D. We propose a general dynamic model in which the melt lens at fast spreading ridges undergoes upward and downward movements as a result of either eruption/replenishment stages or variations in the hydrothermal/magmatic fluxes.
ISSN: 1525-2027

hal-00445249
https://hal.archives-ouvertes.fr/hal-00445249
DOI : 10.1029/2009GC002652

Éditeur(s) : Universite Montpellier II
Résumé : Since 1980, the expansion of a green macro-alga: Valonia aegagropila (C Agardh) is observed in Salses-Leucate lagoon (France). It is currently distributed in the north of the lagoon with important biomasses (40 gDW/m²) eroding the cover of Zostera noltii. The free form of the alga can be transported with the surface or bottom currents depending on seasons. It multiplies mainly by vegetative reproduction. There are few studies on the ecophysiological capacities of V. aegagropila. This work tries to answer why (physiological adaptation) and how (mechanical process of transport) the alga invaded the lagoon, with an approach including observations, experiments in controlled environment and biological and hydrodynamic models. The growth capacities depend on temperature and light intensities, the nutrients absorption rates and internal nitrogen and phosphorus internal quotas were measured and modelled using a Droop model based on internal quota. Vertically transport was studied with laboratory experiments and measurements of biomass transport were made into the lagoon. The biological model (growth, vertical transport, mortality) was coupled to the MARS 3D hydrodynamic model with a meshgrid of 160m. The results show an adaptation of the alga to low availability of phosphorus and an annual growth of biomass controlled by the availability of nutrient during winter. The alga seems to occupy the whole zones where growth is optimal and the risk of invasion of the southern part of the lagoon is limited. This work opens on research prospects on an ecological model (confronting physiological capacities and competition of V. aegagropila, Zostera noltii, green algae and primary production), new physiological experiments, ecological observations and potential valorisation of V. aegagropila.
Depuis 1980, est observée dans l'étang de Salses-Leucate l'expansion d'une macro-algue verte : Valonia aegagropila (C. Agardh). En 2004, elle était présente sur la presque totalité de la moitié nord de la lagune avec des biomasses importantes (jusqu'à 600 gPS/m²). L'algue envahit et érode également la couverture d'herbiers garant de la biodiversité, de la productivité et de la stabilité de l'écosystème. V. aegagropila se reproduit essentiellement de manière végétative (fragmentation des thalles) et possède la particularité de retenir de l'oxygène de la photosynthèse dans sa structure sphérique. Cet oxygène piégé lui donne la possibilité de mouvement sur la verticale et d'être transportée dans le domaine par les courants. Les conditions physico-chimiques de l'étang présentent de fortes variations saisonnières en salinité, en température et en turbidité, ainsi que des apports nutritifs faibles : la production primaire est principalement limitée par le phosphore. Il existe malheureusement peu d'informations sur V. aegagropila ainsi que trop peu de connaissances sur son écophysiologie. Elle semble vivre dans des milieux plutôt oligotrophe dans des régions tropicales à sub-tropicales. Ce travail basé sur une approche d'observations de terrain, d'expérimentations en milieu contrôlé (en laboratoire) et de modélisation des processus, a permis d'une part d'explorer les capacités adaptatives physiologiques de V. aegagropila aux conditions environnementales de l'étang et d'autre part de mettre à jour les modes de fonctionnement de la dynamique spatio-temporelle de la population. Les capacités de croissance ont été mesurées sur un large spectre de température et de lumière. Les capacités d'absorption des sels nutritifs dans l'eau et les facultés de l'algue à stocker l'azote et le phosphore dans ses tissus ont également été étudiées. D'autre part, un modèle de dynamique des populations a été conceptualisé puis développé. Les processus pris en compte dans ce modèle sont la croissance de l'algue (modèle à quota interne), la flottabilité de l'algue et la mortalité par surdensité. Ces processus ont été paramétrés en majeure partie par des expérimentations réalisées en laboratoire. Ce modèle 0D a par la suite était couplé au modèle hydrodynamique MARS3D (modèle Ifremer) mis en place sur la lagune de Salses-Leucate, utilisant deux grilles de calcul (160m ou de 80m de résolution). Les simulations réalisées permettent d'appréhender les capacités spatio-temporelles de la croissance de l'algue dans l'étang, le turnover annuel de la biomasse totale et les attracteurs de biomasse du système sous différents évènements météorologiques. Ces résultats sont comparés avec les répartitions cartographiques de la population observées in situ en 1999 et 2004 et des flux de biomasses mesurés au cours d'observations de terrain entre juin 2003 et septembre 2004. L'ensemble des résultats montre d'une part une adaptation de l'algue à évoluer dans un milieu pauvre en phosphore et d'autre part une croissance annuelle de la biomasse totale qui est principalement contrôlée par les apports hivernaux en sels nutritifs dans la lagune. Les résultats des simulations montrent également que V. aegagropila semble occuper à présent la majeure partie des zones favorables à sa croissance. Il est également montré que si sa capacité de mouvement peut favoriser la dispersion d'individus dans la lagune et accélérer la croissance de la population pour de faibles biomasses initiales, cette même capacité de mouvement joue plutôt un rôle de régulation de la population lorsque la biomasse totale devient importante. On peut penser que le risque de colonisation de l'herbier à zostère de la partie sud de la lagune (bassin de Salses) est limité. Ce travail ouvre enfin des perspectives de recherche sur l'amélioration du modèle de dynamique des populations de l'espèce, sur de nouvelles expérimentations à réaliser ou encore sur la surveillance écologique du milieu. Des propositions sont faites pour concevoir un modèle écologique confrontant les capacités physiologiques des macrophytes (algues vertes, Valonia et zostères) afin d'apréhender les phénomènes de compétitions et les modes de fonctionnement du réseau trophique de la lagune de Salses- Leucate. Des pistes sur la valorisation de la matière algale de V. aegagropila sont enfin proposées.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/these-2453.pdf
http://archimer.ifremer.fr/doc/00000/2453/

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Chromitite pods in the Mayarí-Cristal ophiolitic massif (eastern Cuba) were formed in the Late Cretaceous when island arc tholeiites and MORB-like back-arc basin basalts reacted with residual mantle peridotites and generated chromite-rich bodies enclosed in dunite envelopes. Platinum-group minerals (PGM) in the podiform chromitites exhibit important Os-isotope heterogeneities at the kilometric, hand sample and thin section scales. 187Os/188Os calculated at the time of chromitite crystallization (~90 Ma) ranges between 0.1185 and 0.1295 (γOs = −7.1 to +1.6, relative to enstatite chondrite), and all but one PGM have subchondritic 187Os/188Os. Grains in a single hand sample have initial 187Os/188Os that spans from 0.1185 to 0.1274, and in one thin section it varies between 0.1185 and 0.1232 in two PGM included in chromite which are only several millimeters apart. As the Os budget of a single micrometric grain derives from a mantle region that was at least several m3 in size, the variable Os isotopic composition of PGM in the Mayarí-Cristal chromitites probably reflects the heterogeneity of their mantle sources on the 10-100 m scale. Our results show that this heterogeneity was not erased by pooling and mingling of individual melt batches during chromitite crystallization but was transferred to the ore deposits on mineral scale. The distribution of the Os model ages calculated for PGM shows four main peaks, at ~100, 500, 750 and 1,000 Ma. These variable Os model ages reflect the presence of different depleted domains in the oceanic (Pacific-related) upper mantle of the Greater Antilles paleo-subduction zone. The concordance between the age of crystallization of the Mayarí-Cristal chromitites and the most recent peak of the Os model age distribution in PGM supports that Os in several grains was derived from fertile domains of the upper mantle, whose bulk Os isotopic composition is best approximated by that of enstatite chondrites; on the other hand, most PGM are crystallized by melts that tapped highly refractory mantle sources.
ISSN: 0010-7999

hal-00822742
https://hal.archives-ouvertes.fr/hal-00822742
DOI : 10.1007/s00410-010-0575-2

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Although ants may induce community-wide effects via changes in physical habitats in terrestrial environments, their influence on aquatic communities living in plant-held waters remains largely underexplored. The neotropical tank-bromeliad Aechmea mertensii (Bromeliaceae) occurs along forest edges in ant-gardens initiated by Camponotus femoratus or by Pachycondyla goeldii. Its leaves form wells that hold rainwater and provide suitable habitats for many aquatic organisms. We postulated that these ant-plant mutualisms indirectly affect the microbial community structure via changes in the environmental conditions experienced by the plants. To test this hypothesis, we analyzed the protist communities from 63 tank-bromeliads associated with either C. femoratus or P. goeldii (hereafter Cf-Aechmea and Pg-Aechmea) along a forest edge in French Guiana. For each plant, a large number of environmental variables (including habitat structure, food resources, incident radiation and the presence of aquatic invertebrates) were quantified to determine their relative importance in driving any observed differences across ant-associated plants. Pg-Aechmea are located in sun-exposed areas and hold low volumes of water and low amounts of detritus, whereas Cf-Aechmea are located in partially shaded areas and accumulate higher amounts of water and detritus. Protists (i.e., protozoa and algae) inhabiting Cf-Aechmea exhibit greater richness and abundances than those in Pg-Aechmea. Variations in detritus content, number of leaves, incident radiation, and the epiphyte richness of the ant-garden were the main factors explaining the variation in protist richness. A shift in the functional group composition of protists between bromeliads tended by different ant species suggested that mutualistic ants indirectly mediate changes in the microbial food web.
Basic and Applied Ecology

hal-00913126
https://hal.archives-ouvertes.fr/hal-00913126
https://hal.archives-ouvertes.fr/hal-00913126/document
DOI : 10.1016/j.baae.2012.10.002
OATAO : 10190

Éditeur(s) : HAL CCSD
Résumé : International audience
Background Orodental diseases include several clinically and genetically heterogeneous disorders that can present in isolation or as part of a genetic syndrome. Due to the vast number of genes implicated in these disorders, establishing a molecular diagnosis can be challenging. We aimed to develop a targeted next-generation sequencing (NGS) assay to diagnose mutations and potentially identify novel genes mutated in this group of disorders. Methods We designed an NGS gene panel that targets 585 known and candidate genes in orodental disease. We screened a cohort of 101 unrelated patients without a molecular diagnosis referred to the Reference Centre for Oro-Dental Manifestations of Rare Diseases, Strasbourg, France, for a variety of orodental disorders including isolated and syndromic amelogenesis imperfecta (AI), isolated and syndromic selective tooth agenesis (STHAG), isolated and syndromic dentinogenesis imperfecta, isolated dentin dysplasia, otodental dysplasia and primary failure of tooth eruption. Results We discovered 21 novel pathogenic variants and identified the causative mutation in 39 unrelated patients in known genes (overall diagnostic rate: 39%). Among the largest subcohorts of patients with isolated AI (50 unrelated patients) and isolated STHAG (21 unrelated patients), we had a definitive diagnosis in 14 (27%) and 15 cases (71%), respectively. Surprisingly, COL17A1 mutations accounted for the majority of autosomal-dominant AI cases. Conclusions We have developed a novel targeted NGS assay for the efficient molecular diagnosis of a wide variety of orodental diseases. Furthermore, our panel will contribute to better understanding the contribution of these genes to orodental disease. Trial registration numbers NCT01746121 and NCT02397824
Journal of Medical Genetics

hal-01272929
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01272929
DOI : 10.1136/jmedgenet-2015-103302
PUBMED : 26502894

Éditeur(s) : HAL CCSD Elsevier
Résumé :  
The within-population spatial structure of genetic diversity is shaped by demographic processes, including historical accidents such as forest perturbations. Information drawn from the analysis of the spatial distribution of genetic diversity is therefore inherently linked to demographic-historical processes that ultimately determine the fate of populations. All adult trees and saplings in a 1.4-ha plot within a mixed Norway spruce (Picea abies [L.] Karst) stand were characterised by means of chloroplast (paternally inherited) markers, and a large sub-sample of these were genotyped at mitochondrial (maternally inherited) molecular markers. These data were used to analyse the spatial distribution of genetic variation and to compare the patterns corresponding to the two marker types. The plot presented non-homogeneous local stem density in the younger cohorts, and the indirect effect of this source of variation on the spatial genetic structure was investigated. Results suggest that (i) spatially limited seed dispersal induced patchiness in genotype distribution, while pollen flow had a homogenising effect; (ii) deviations from random spatial structure were stronger in the demographically most stable portions of the stand, while they were weaker where sudden bursts of regeneration occurred; (iii) spatially overlapping adult and sapling cohorts displayed the same spatial genetic structure (stronger on stable areas, weaker in portions of the stand undergoing events of intense regeneration), which was substantiated by the influence of local demographic processes. Regeneration dynamics as modulated by demography thus influences the distribution of genetic diversity within the stand both in the younger life stages and in the adult population.
ISSN: 0378-1127

hal-01032063
https://hal.archives-ouvertes.fr/hal-01032063
DOI : 10.1016/j.foreco.2008.03.023

Éditeur(s) : HAL CCSD BioScientifica
Résumé : International audience
The general rules established from mammalian species for the regulation of spermatogenesis by gonadotropins may not be fully relevant in fish. Particularly, Fsh is as potent as Lh to stimulate steroidogenesis and the Fsh receptor is expressed in Leydig cells. In seasonal breeders, Fsh is likely the major gonadotropin involved in spermatogenesis onset and Lh is required to support spermatogenesis progression and gamete release. However, the genes that relay the action of Fsh and Lh have been poorly investigated in fish. The present study was aimed at identifying gonadotropin-dependent genes expressed in the testis during fish puberty. We cultured pubertal trout testicular explants for 96 h, with or without gonadotropin, and analyzed transcriptome variations using microarrays. Fsh and Lh had similar effects on a large group of genes while other genes were preferentially regulated by one or the other gonadotropin. We showed that most of the responsive genes were expressed in somatic cells and exhibited relevant patterns during the seasonal reproductive cycle. Some genes preferentially modulated by Lh could be involved in testicular cell fate (pvrl1 and bty) or sperm maturation (ehmt2 and racgap1) and will deserve further examination. Besides Fsh's effects on the steroidogenic pathway, our study demonstrates that Fsh coordinates relevant stimulatory and inhibitory paracrine factors known to regulate early germ cell proliferation and differentiation. Some of these genes belong to major regulatory pathways including the Igf pathway (igf1b/igf3 and igfbp6), the Tgfb pathway (amh, inha, inhba, and fstl3), the Wnt pathway (wisp1), and pleiotrophin (mdka).
ISSN: 0952-5041

inserm-00812401
http://www.hal.inserm.fr/inserm-00812401
DOI : 10.1530/JME-12-0197
PUBMED : 23045716

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The island of Taiwan is located on the convergent boundary between the Philippine Sea plate and the Chinese continental margin. It offers very active mountain building and collapsing processes well illustrated by the rugged topography, rapid uplift and denudation, young tectonic landforms, active faulting and numerous earthquakes. In this paper, using simple models, we have estimated vertical movements and associated absolute gravity variations which can be expected along a profile crossing the southern part of the island and probably suffering the highest rates of rising. The two different tectonic styles proposed for the island, thin-skinned and thick-skinned, were taken into account. Horizontal and vertical movements were modeled by an elastic deformation code. Gravity variations due to these deformations are then modeled at a second step. They are dominated by plate and free-air effects, i.e. elevation of the topography, with several mu Gal yr(-1). By comparison, gravity changes generated by mass transfers are weak: maximum 0.1 mu Gal yr(-1) with the thin-skinned tectonic and 0.3 mu Gal yr(-1) with the thick-skinned tectonic. Though elastic rheology has limitations, this modeling offers interesting results on what gravity signal can be expected from the AGTO project (Absolute Gravity in the Taiwanese Orogen), which proposes to study the dynamic of these mountain ranges using absolute gravimetry (AG) and also including relative gravimetry (RG) and GPS measurements.
ISSN: 0264-3707

hal-00456035
https://hal.archives-ouvertes.fr/hal-00456035
DOI : 10.1016/j.jog.2009.09.004

Éditeur(s) : Taylor & Francis Ltd
Résumé : A new method is developed to estimate daily turbulent airsea fluxes over the global ocean on a 0.25 degrees grid. The required surface wind speed (w(10)) and specific air humidity (q(10)) at 10m height are both estimated from remotely sensed measurements. w(10) is obtained from the SeaWinds scatterometer on board the QuikSCAT satellite. A new empirical model relating brightness temperatures (T-b) from the Special Sensor Microwave Imager (SSM/I) and q(10) is developed. It is an extension of the author's previous q(10) model. In addition to T-b, the empirical model includes sea surface temperature (SST) and airsea temperature difference data. The calibration of the new empirical q(10) model utilizes q(10) from the latest version of the National Oceanography Centre airsea interaction gridded data set (NOCS2.0). Compared with mooring data, the new satellite q(10) exhibits better statistical results than previous estimates. For instance, the bias, the root mean square (RMS), and the correlation coefficient values estimated from comparisons between satellite and moorings in the northeast Atlantic and the Mediterranean Sea are 0.04gkg(1), 0.87gkg(1), and 0.95, respectively. The new satellite q(10) is used in combination with the newly reprocessed QuikSCAT V3, the latest version of SST analyses provided by the National Climatic Data Center (NCDC), and 10m air temperature estimated from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses (ERA-Interim), to determine three daily gridded turbulent quantities at 0.25 degrees spatial resolution: surface wind stress, latent heat flux (LHF), and sensible heat flux (SHF). Validation of the resulting fields is performed through a comprehensive comparison with daily, in situ values of LHF and SHF from buoys. In the northeast Atlantic basin, the satellite-derived daily LHF has bias, RMS, and correlation of 5Wm(2), 27Wm(2), and 0.89, respectively. For SHF, the statistical parameters are 2Wm(2), 10Wm(2), and 0.94, respectively. At global scale, the new satellite LHF and SHF are compared to NOCS2.0 daily estimates. Both daily fluxes exhibit similar spatial and seasonal variability. The main departures are found at latitudes south of 40 degrees S, where satellite latent and sensible heat fluxes are generally larger.
International Journal Of Remote Sensing (0143-1161) (Taylor & Francis Ltd), 2013-07 , Vol. 34 , N. 14 , P. 5243-5261

Droits : 2013 Taylor & Francis
http://archimer.ifremer.fr/doc/00137/24825/23575.pdf
DOI:10.1080/01431161.2013.787502
http://archimer.ifremer.fr/doc/00137/24825/

Éditeur(s) : Public Library Science
Résumé : Where conservation resources are limited and conservation targets are diverse, robust yet flexible priority-setting frameworks are vital. Priority-setting is especially important for geographically widespread species with distinct populations subject to multiple threats that operate on different spatial and temporal scales. Marine turtles are widely distributed and exhibit intra-specific variations in population sizes and trends, as well as reproduction and morphology. However, current global extinction risk assessment frameworks do not assess conservation status of spatially and biologically distinct marine turtle Regional Management Units (RMUs), and thus do not capture variations in population trends, impacts of threats, or necessary conservation actions across individual populations. To address this issue, we developed a new assessment framework that allowed us to evaluate, compare and organize marine turtle RMUs according to status and threats criteria. Because conservation priorities can vary widely (i.e. from avoiding imminent extinction to maintaining long-term monitoring efforts) we developed a "conservation priorities portfolio" system using categories of paired risk and threats scores for all RMUs (n = 58). We performed these assessments and rankings globally, by species, by ocean basin, and by recognized geopolitical bodies to identify patterns in risk, threats, and data gaps at different scales. This process resulted in characterization of risk and threats to all marine turtle RMUs, including identification of the world's 11 most endangered marine turtle RMUs based on highest risk and threats scores. This system also highlighted important gaps in available information that is crucial for accurate conservation assessments. Overall, this priority-setting framework can provide guidance for research and conservation priorities at multiple relevant scales, and should serve as a model for conservation status assessments and priority-setting for widespread, long-lived taxa.
Plos One (1932-6203) (Public Library Science), 2011-09 , Vol. 6 , N. 9 , P. 1-14

Droits : 2011 Wallace et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License
http://archimer.ifremer.fr/doc/00050/16097/13573.pdf
DOI:10.1371/journal.pone.0024510
http://archimer.ifremer.fr/doc/00050/16097/