Éditeur(s) : HAL CCSD
Résumé :  
A closed depression is defined as a geomorphologic element where a sediment depository is encircled by hillslopes. Despite the fact that closed depressions are often the only stagnant water points in many European landscapes, few ecological researches on their plant assemblages have been done. The main goal of this study was to give first results of the environmental factors responsible for the vegetation composition, richness and rarity in the closed depressions of the Lorraine biogeographical district (Belgium, France and grand-duche de Luxembourg). We surveyed for plant presence 85 forest and 77 grassland closed depressions. For each site, wetland area, local environmental factors and regional connectivities registered. For each species, the Ellenberg values were compiled. To investigate the main source of variation in species composition and in species richness (including richness in rare species), Non-metric Multidimensional Scaling analyses and Generalized Linear Models were respectively used. Species pools in forest (forest and preforest species) and in grassland (bog plants, pioneers, helophytes) were quite different. In both landscapes, a gradient from plants typical of basic high-productive soils to plants typical of acid low-productive soils reflects a shared successional gradient. The accumulation of organic matter allowed the establishment of Sphagnum spp., which slowly acidified the soil and thus acted as ecosystem engineers for the arrival of bog plants. Moreover, the species composition was additionally driven by the plant light tolerance in forests and by the plant water requirements in grasslands. Mechanisms of species accumulation (increase in species richness) were different in forests and in grasslands: respectively related to the plant light tolerance and to the wetland area. At the regional level, the averaged soil productivity was negatively related to the richness in rare species. Indeed, perennial highly-competitive plants such as Glyceria spp., Iris pseudacorus or Urtica dioica impeded the establishment of smaller and rarer species. At the habitat level, isolated closed depressions (due to either low connectivity or low grazing pressure) have more habitat rare species, giving evidences of dispersal limitation in plant assemblages of closed depressions.
7th INTECOL International Wetland Conference
Utrecht, Netherlands

hal-01032381
https://hal.archives-ouvertes.fr/hal-01032381

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
We use digital elevation models and satellite imagery data completed with field observations to develop an integrated morphotectonic analysis of the anomalous topography of the Central Cordillera of Patagonia between 46 degrees S and 48 degrees S, in a region overlying subducted segments of the Chile Spreading Ridge. This region shows a number of peculiar features, not expected in a normal subduction-related belt located away from a buried spreading center. First, it is characterized by overall short-wavelength topography and highly contrasted reliefs, typical of deeply incised young mountain belts, but surprisingly, also by an average very low elevation of similar to 900 m. Second, the Cordillera lacks central high reliefs; instead, there is a central, depressed domain with average low slope gradients including the deepest point of the study area (300 m below sea level in the bottom of Lake General Carrera/Buenos Aires). This depressed area is flanked by western and eastern regions of higher elevation having opposite general slope dips. To the east, the central Patagonian Cordillera is now separated from the flat plains of the Pampean domain (representing its former piedmont) and several elevated basaltic plateaus (mesetas) by 160 degrees N-180 degrees N trending morphotectonic corridors and the western border scarps of the mesetas. These scarps correspond to neotectonic features controlled by recent vertical faults, mostly active after 3 Ma. Remnants of a former peneplain, the Avellanos surface, are widespread within the entire Cordilleran region. From geological evidence, this peneplain formed between 15 and 4 Ma and was connected originally with the mesetas domain and now is dissected by these corridors. It is shown that a negative inversion related to extensional and strike-slip faulting occurred in the frontal region of the Cordillera at 3 Ma synchronously with the emplacement of magmatic products. Timing of the extensional deformation in central Patagonia is concomitant with the migration at depth of different segments of the South Chile Ridge, which entered the trench at 6 and 3 Ma, respectively, and the consequent opening of a slab window allows asthenospheric hot mantle to reach lithospheric regions. Finally, migration of segments of the Chile Spreading Ridge since 6 Ma triggered regional uplift of the Cordillera followed by limited extension in relation with increased thermal weakening of the crust.
ISSN: 0278-7407

hal-00486334
https://hal.archives-ouvertes.fr/hal-00486334
DOI : 10.1029/2009TC002453

Éditeur(s) : Elsevier Sci Ltd
Résumé : Several marine geophysical data and piston-coring surveys acquired during the last decade allow one to better understand the close dynamic interactions between the sand-rich Orinoco turbidite system and the compressional structures of the Barbados prism. These interactions have been active since Eocene time as illustrated by the study of outcrops onshore Barbados Island. Because of strong morphologic and tectonic control in the east-Caribbean active margin, the present-day Orinoco turbiditic pattern system does not exhibit a classic fan geometry. The sea-floor geometry between the slope of the front of the Barbados prism and the slope of the South-American margin induces the convergence of the turbidite channels toward the abyssal plain, at the front of the accretionary prism. Also, whereas in most passive margins the turbidite systems are organized upstream to downstream as canyon, channel-levee and lobes, here, due to the tectonic control, the sedimentary system is organized upstream to downstream as channel-levee, canyons and channelized lobes. Indeed, at the edge of the Orinoco platform, the system has multiple sources with several distributaries and downstream the channel courses are complex with frequent convergences or divergences that are emphasized by the effects of the undulating seafloor tectonic morphologies associated with active thrust tectonics and mud volcanism. On top of the accretionary prism, turbidite sediments are filling transported piggy-back basins whose timing of sedimentation vs. deformation is complex. While erosion processes are almost absent on the highly subsiding Orinoco platform and in the upper part of the turbidite system, they develop mostly between 2000 and 4000 m of water depth, above the compressional structures of the Barbados prism (canyons up to 3 km wide and 300 m deep). In the abyssal plain, the main turbiditic channel develops toward the east and connects with the Vidal mid-Atlantic channel. The sediments transported in this channel are filling several elongated basins linked with fracture zones (notably the Barracuda Basin), and finally end their course in the Puerto-Rico trench, the deepest morphologic depression of the region. Piston-cores have demonstrated that turbidite sediments above the accretionary prism and in the abyssal plain are mostly coarse sandy deposits covered by recent pelagic planktonic-rich sediments, which corresponds to slower sand deposition during the post-glacial sea level rise. Numerical stratigraphic modelling suggests that during the last glacial event, the main depocentres were located above the tectonic prism and in the abyssal plain, at the front of the prism and that, during the Holocene eustatic rise, a large accommodation space formed on the shelf confining sedimentation mostly on the Orinoco deltaic platform and producing a starvation downstream in the turbidite system.
Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2015-06 , Vol. 64 , P. 76-103

Droits : 2015 Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00252/36373/34913.pdf
DOI:10.1016/j.marpetgeo.2014.12.015
http://archimer.ifremer.fr/doc/00252/36373/

Éditeur(s) : Neidine Editeurs
Résumé : This article of the number 10 of Tai Kona is the natural complement to the article appeared under the number 8, dedicated to the submarine geodiversity of the New Caledonian EEZ. The first article notably put the bases of knowledge on the history, the origins and the specificities of the geodiversity of the maritime spaces of the New Caledonian EEZ. The present article focuses on four of the major stakes which are put: 1/ the scientific ones relative to an exceptional submarine geologic context, 2 /the economic ones connected to such a favorable geologic context and to mineral resources exploitation perspectives which are no more domain of the utopia, 3/ the major environmental ones with the existence of a semi deep and deep major biodiversity and 4/ the stakes on the natural risks of a zone in the active local or regional seismicity. The conclusions of this article underline all the major challenges, in the interface of four main quoted questions, which New Caledonia must know how to raise.
Cet article du numéro 10 de Tai Kona est le complément naturel de l’article paru sous le numéro 8, dédié à la géo diversité sous-marine de la Nouvelle-Calédonie. Le premier article posait notamment les bases de connaissance sur l’histoire, les origines et les spécificités de la géo diversité des espaces maritimes de la ZEE calédonienne. Le présent article se focalise sur quatre des enjeux majeurs qui sont posés aux plans : 1/ scientifique, relatifs à un contexte géologique sous-marin exceptionnel, 2/ économique, liés à un contexte géologique favorable et à des perspectives d’exploitation de ressources qui ne sont plus du domaine de l’utopie, 3/ environnemental avec là encore un contexte totalement original et l’existence d’une biodiversité semi profonde et profonde majeure et 4/ des risques naturels d’une zone à la sismicité locale ou régionale active. Les conclusions de cet article soulignent tous les enjeux majeurs, à l’interface des quatre grands défis cités, que la Nouvelle-Calédonie doit savoir relever.
Tai Kona (2269-7535) (Neidine Editeurs), 2014-09 , N. 10 , P. 24-37

Droits : 2014 Tai Kona
http://archimer.ifremer.fr/doc/00209/32013/30443.pdf
http://archimer.ifremer.fr/doc/00209/32013/

Éditeur(s) : HAL CCSD
Résumé : International audience
—Managing spatial reservoirs of malaria infection plays a crucial role in effective disease control. In this paper, a reservoir of infection refers to one or more interconnected subpopulations that sustain the epidemic at the level of the metapopulation to which applying a (linear) control strategy suffices to eradicate the disease in the whole system. We propose a numerical method to explain the steps for identifying reservoirs of malaria infection within n connected regions with the explicit movement of human population from the previous theoretical results in order to design an efficient computational tool. Furthermore, we determine the minimal percentage (critical vaccination fraction) of susceptible individuals in the reservoirs that should be protected to eliminate malaria. The costs and cost-effectiveness of malaria control interventions were analysed considering two strategies of control. (i) protecting the minimal fraction of susceptible individual; (ii) protecting any fraction greater than the minimal fraction. Cost-effectiveness analysis shows that the less cost and more effective strategy is to vaccinate (or protect) the minimal fraction of susceptible human in the reservoir of infection to halt outbreak. A numerical example provides insight into the efficiency of this approach.
IAENG International Journal of Applied Mathematics

Droits : info:eu-repo/semantics/OpenAccess
hal-01683268
https://hal.univ-antilles.fr/hal-01683268
https://hal.univ-antilles.fr/hal-01683268/document
https://hal.univ-antilles.fr/hal-01683268/file/ZongoDorvilleGouba28Janvier2017.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé :  
Classifying species by shared life-history traits is important if common ecological response groups are to be identified among different species. We investigated how habitat area, local and regional factors shape plant communities in small isolated closed depressions, and how the species richness is related to the interplay between environmental factors and specific life-history trait combinations. In Central-Western Europe, 169 closed depressions were completely Surveyed for plant presence in two highly contrasted landscapes (forested and open landscapes). All species were clustered into 9 Emergent Groups based oil 10 life-history traits related to plant dispersal, establishment and persistence. Habitat areas were related to species presence using logistic regressions. Most Emergent Groups were more area-dependent in open than in forested landscapes, owing to heterogeneous light levels in forest weakening the species-area relationship. In open landscapes, Floating Hydrophytes were severely underrepresented in very small depressions, owing to the absence of waterfowl poulation. Local environmental and regional factors were related to species richness using Generalized Linear Models. In open landscapes, local environmental factors such as water conductivity or soil productivity are respectively the main predictors. In forested landscapes, the abundance of most Emergent Groups Was better predicted by regional factors, i.e., habitat connectivity and distance to the forest edge. Forested landscapes strongly impeded the closed depressions' colonization by the less mobile Emergent Groups Such as Large-seeded Perennials.
ISSN: 1146-609X

hal-01032144
https://hal.archives-ouvertes.fr/hal-01032144
DOI : 10.1016/j.actao.2009.02.002

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 Elsevier
Résumé : Remerciements :- Dr. Jacques Delabie- Andrea Yockey-Dejean- Geoff Brown- Jean-Pierre Andrieu
Background: Most ant venoms consist predominantly of small linear peptides, although some contain disulfide linked peptides as minor components. However, in striking contrast to other ant species, some Anochetus venoms are composed primarily of disulfide-rich peptides. In this study, we investigated the venom of the ant Anochetus emarginatus with the aim of exploring these novel disulfide-rich peptides.Methods: The venom peptidome was initially investigated using a combination of reversed-phase HPLC and mass spectrometry, then the amino acid sequences of the major peptides were determined using a combination of Edman degradation and de novo MS/MS sequencing. We focused on one of these peptides, U-1-PONTX-Ae1a (Ae1a), because of its novel sequence, which we predicted would form a novel 3D fold. Ae1a was chemically synthesized using Fmoc chemistry and its 3D structure was elucidated using NMR spectroscopy. The peptide was then tested for insecticidal activity and its effect on a range of human ion channels.Results: Seven peptides named poneritoxins (PONTXs) were isolated and sequenced. The three-dimensional structure of synthetic Ae1a revealed a novel, compact scaffold in which a C-terminal beta-hairpin is connected to the N-terminal region via two disulfide bonds. Synthetic Ae1a reversibly paralyzed blowflies and inhibited human L-type voltage-gated calcium channels (Ca(v)1).Conclusions: Poneritoxins from Anochetus emarginatus venom are a novel class of toxins that are structurally unique among animal venoms.General significance: This study demonstrates that Anochetus ant venoms are a rich source of novel ion channel modulating peptides, some of which might be useful leads for the development of biopesticides.
ISSN: 0304-4165

hal-01511987
https://hal.archives-ouvertes.fr/hal-01511987
https://hal.archives-ouvertes.fr/hal-01511987/document
https://hal.archives-ouvertes.fr/hal-01511987/file/2016_Touchard_Biochimica_Biophysica_%7B4B3BE6A3-AE83-4C6E-B678-BBFB5CC84AF7%7D.pdf
DOI : 10.1016/j.bbagen.2016.07.027

Éditeur(s) : American Geophysical Union
Résumé : The origins and fates of the Atlantic salinity maximum water (SMW), formed through excess evaporation in the tropics and subtropics of both hemispheres, are studied using monthly mean outputs of a numerical simulation of the world ocean climatological circulation. After defining formation domains from the surface salinity field and the vertical stratification, a Lagrangian technique is used to estimate the formation rates and main pathways in each hemisphere and the role of this water in the framework of the warm water return flow of the meridional overturning cell. Formation rates around 9 and 11 Sv are found in the Southern and Northern Hemispheres, respectively. While the export of the southern SMW from its formation area is realized by the western boundary currents, that of the northern SMW mainly results from interior subduction. Equatorward of the formation regions, a fraction of each SMW variety is entrained in the subtropical cells that connect the subtropics to the equatorial region. Poleward of them, both varieties are seen to feed the regions of subtropical mode water (STMW) formation around 35degrees of latitude in both hemispheres. The bulk of the transport associated with each variety eventually turns northward: This amounts to similar to6 Sv of southern SMW gathered in the North Brazil Undercurrent (NBUC), and similar to10 Sv of northern SMW found in the Gulf Stream at 35degreesN, of which 8 Sv have gone through the Caribbean Sea. Of the 13.4-Sv northward transport of the meridional overturning cell estimated by the model at 47degreesN, more than 50% (6.9 Sv) is found to have transited through at least one of the SMW regions. This gives an indication of the likely important role of SMW formation in the observed northward salinity increase of the upper Atlantic Ocean.
Journal of Geophysical Union - Research C - Oceans (0148-0227) (American Geophysical Union), 2002-09 , Vol. 107 , N. C10 , P. NIL_610-NIL_624

Droits : 2002 by the American Geophysical Union
http://archimer.ifremer.fr/doc/2002/publication-769.pdf
DOI:10.1029/2002JC001318
http://archimer.ifremer.fr/doc/00000/769/

Éditeur(s) : HAL CCSD
Résumé : International audience
Continental erosion and weathering destroy parts of the stratigraphic record. Analyses of the sedimentary filling of paleokarsts help completing the geological record of regions that have been submitted to post-depositional, long-term, continental evolution. Jurassic carbonate platform of Languedoc (South of France) has undergone several karstification phases from Cretaceous to Neogene. Later incision of canyons through the carbonate massifs allows to observe paleokarsts over 400m depth, within the massifs. Paleokarsts are partly filled with sediments. Some have yielded marine bioclasts (echinoderms, radiolars), foraminifera and nannofossils; others are composed of polygenic detrital sediments, including sources from the upstream Paleozoic basement (Cevennes). The age of the filling of successive paleokarsts can be constrained by structural relationships and by biostratigraphy. These findings suggests 1) the marine elements of the karstic filling relate to a Late Cretaceous to Early Paleocene interval, while 2) the Paleozoic basement-sourced-sediments were trapped in the karst during Miocene to Present. Karstic sediment containing Early Paleocene foraminifera and nannofossils are found in paleokarsts cavities distributed across the entire thickness of the carbonate massif (≥350m). This requires base-level lowering and associated karstification, followed by base-level rise and karst filling of at least 350 m amplitude, respectively. The time interval corresponding to the occurrence of foraminifera and nannofossils in karsts covers 10 Myrs ; surprisingly, no equivalent marine sediments are preserved on the surface. In addition, analyses of the different forams species suggests several (up to 3) distinct karstification and marine filling cycles. Finally, sedimentological facies analysis of the karst filling reveals the following succession of processes: low energy settling of mudstone, high energy reworking, transport and deposition of silts and sandstones within the karst system. Integration of geological, paleontological and sedimentological data, leads to a polyphase scenario in response to repeated base-level variations, more than 350m amplitude. Such an amplitude excludes eustacy, and the improbable repeated sequence of uplift and subsidence rules out tectonics, as driving forces for base-level change, respectively. We propose that the high-amplitude base-level changes results from a succession of desiccation-flooding events of an endorheic, silled, basin during Early Paleogene. The later detrital assemblage sourced in the Cevennes occurs on perched paleosurfaces and in karst cavities across the whole 350m-deep canyon walls. When found on paleosurfaces, they correspond to the south-flowing Early Miocene fluvial drainage, and can be correlated downstream with the marine, well dated, Early Miocene, sediments. When found within the karst cavities, they correspond to successive base-level surfaces connected to the progressive incision of the canyon. This canyon incision is coeval with a Late Miocene uplift of the hinterland.
24th International Karstological School "Classical karst" : Paleokarst
Postojna, Slovenia

hal-01306683
https://hal-brgm.archives-ouvertes.fr/hal-01306683
https://hal-brgm.archives-ouvertes.fr/hal-01306683/document
https://hal-brgm.archives-ouvertes.fr/hal-01306683/file/Abstract_IKS.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Absolute earthquake hypocenter locations have been determined in the area offshore eastern Taiwan, at the Southernmost Ryukyu subduction zone. Location process is run within a 3D velocity model by combining the Taiwanese and neighboring Japanese networks and using the 3D MAXI technique. The study focuses on the most active seismic cluster in the Taiwan region that occurs in the forearc domain offshore eastern Taiwan. Earthquakes distribute mainly along 2 active planes. The first one aligns along the subduction interface and the second one, shallower affects the overriding margin. Focal mechanisms within the shallow group indicate that nodal planes are either compatible with high-angle back-thrusts or low-angle thrusts. The active seismic deformation exclusively indicates reverse faulting revealing that the forearc basement undergoes trench-perpendicular strong compression. By integrating the seismological image into the regional context, we favor the hypothesis in which the dense seismicity occurring offshore marks the activity of en-échelon high-angle reverse faults accommodating the uplift of a broken piece of Ryukyu Arc basement, called Hoping Basement Rise. The uplift is inferred to be caused by the subduction of an oceanic relief, either exotic block, seamount or oceanic crust sliver. Our favored solution satisfies the narrowness of epicenter's cluster along the Hoping Canyon, and the observation of high-angle active faults on seismic lines crossing the area. Furthermore, this solution is compatible with the active uplift of the Hoping Rise demonstrated from morphological and sedimentological data. We do not exclude the branching of the high-angle reverse faults system onto a splay fault connected with the subduction interface but further investigations are needed to map precisely the 3D distribution of active faults that break the margin.
ISSN: 0040-1951

hal-00407726
https://hal.archives-ouvertes.fr/hal-00407726
DOI : 10.1016/j.tecto.2007.11.018

Éditeur(s) : HAL CCSD Inter-Research
Résumé : International audience
Many large groupers form spawning aggregations, returning to the same spawning sites in consecutive spawning seasons. Connectivity between spawning aggregations is thus assured by larval dispersal. This study looks into the genetic structure and gene flow among spawning aggregations of a large grouper, the gulf coney Hyporthodus acanthistius, in the northern Gulf of California. First, using the mitochondrial control region and 11 microsatellites, we calculated FST metrics and conducted a Bayesian clustering analysis to determine structure among 5 spawning aggregations. Shallow genetic structure was found, separating the southernmost spawning aggregate from the remainder. Second, we used the results from the structure analysis and local water circulation patterns to delineate 3 distinct models of gene flow. The best-supported model, in which the southernmost spawning aggregate formed one group and all other spawning aggregates were nested into a second group, was the one that was consistent with water circulation during the species’ spawning season. Larval retention within a seasonal anticyclonic gyre that formed during the gulf coney’s spawning season may be responsible for the patterns found. This study highlights the importance of local oceanographic conditions in dictating the structure among spawning aggregations even at small geographic scales and contributes to informed management plans for this overexploited grouper.
Marine Ecology Progress Series

hal-01301199
https://hal-univ-perp.archives-ouvertes.fr/hal-01301199
DOI : 10.3354/meps10637

Résumé : La banane plantain (Musa paradisiaca) est l’aliment de base de millions de personnes dans le monde et sa culture génère des revenus permanents pour un grand nombre d’agriculteurs, dans des plantations de taille petite ou moyenne. Comme dans d’autres régions tropicales, la culture du plantain en Guadeloupe et en Haïti est soumise à de fortes contraintes parasitaires aussi bien telluriques (i.e. du sol : nématodes phytoparasites et charançon du bananier) qu’aériennes (Cercosporiose noire notamment). Les moyens de lutte conventionnels reposent sur l’usage de produits de synthèse dont les effets néfastes sur l’environnement (sols, eaux, animaux) comme sur la santé humaine ne sont plus supportables. Il est donc urgent de réfléchir à des solutions agro-écologiques permettant de rétablir les équilibres biologiques, de maintenir une bonne qualité des sols et une production optimale dans les systèmes de culture plantains. C’est le but de ce travail de thèse qui couple la réalisation d’un diagnostic agro-écologique dans des parcelles paysannes, et le test d’alternatives agro-écologiques en milieu semi-contrôlé. Pour ce faire, une typologie des systèmes de culture plantains a été réalisée à l’issue d’une enquête agro-environnementale dans les deux zones d’étude. Elle a permis de sélectionner 23 parcelles en Guadeloupe et 12 en Haïti dans lesquelles un diagnostic agro-écologique a été conduit. Sur la base de ce diagnostic et de la recherche d’alternatives agro-écologiques à l’usage des produits chimiques, une expérimentation au champ a été mise en place en Guadeloupe en station de recherche, permettant le test de trois pratiques culturales innovantes pour le plantain (seules et combinées), à savoir : i) l’introduction d’une plante de service Paspalum notatum pour la gestion des adventices et la réduction de l’utilisation d’herbicides ; ii) l’apport de vermicompost pour le contrôle des nématodes phytoparasites inféodés au bananier plantain et la fertilisation de celui-ci ; iii) l’utilisation de plants sains PIF (Plants Issus de Fragments de tiges) indemnes de nématodes et de larves de charançon du bananier. La typologie des systèmes de culture plantains révèle que : i) en Guadeloupe les précédents : jachère, ananas et banane plantain sont prédominants avec un niveau d’intensification faible (apports d’intrants chimiques faibles et peu fréquents) ou élevé (apports d’intrants chimiques élevés et plus fréquents) ; ii) en Haïti, les précédents : jachère, banane plantain et manioc prédominent avec un niveau d’intensification faible ou nul (apport d’intrants inexistant). Les résultats du diagnostic agro-écologique montrent que, i) lorsque le niveau d’intensification est faible, les bananeraies plantains pérennes et le précédent-ananas permettent de maintenir une bonne qualité du sol et une bonne régulation des parasites telluriques ; ii) lorsque le niveau d’intensification est fort, les populations d’ingénieurs du sol diminuent drastiquement, alors que le cortège parasitaire tellurique augmente sans que cela n’affecte l’obtention de bons niveaux de rendement instantannés (parcelles précédées d’ananas ou d’une jachère principalement) ; iii) en absence totale de fertilisation, il résulte une diminution de l’activité biologique du sol mais aussi du rendement du plantain, exacerbé par le choix des précédents-culturaux (manioc ou banane plantain) en lien avec les contraintes pédoclimatiques et la maladie des raies noires (Cercosporiose noire) causée par Mycosphaerella fijiensis, notamment au sein des parcelles Haïtiennes ; iv) la succession plantain/plantain est la plus pénalisante vis-à-vis de la culture du plantain, car quelque soit le niveau d’intensification, le rendement reste relativement faible, en lien avec une dégradation de l’état sanitaire, comparativement aux autres précédents.
Plantain (Musa paradisiaca) is the staple food of millions of people worldwide and its cropping generates ongoing revenues for many farmers who are planting small or medium size areas. As in other tropical regions, plantain cultivation in Guadeloupe and Haiti is under heavy parasitic constraints terrestrial (plant-parasitic nematodes and banana weevil) as well as aerial (black Sigatoka in particular). Conventional means of control based on the use of synthetic products which adverse effects on the environment (soil, water, animals ...) as on human health are not bearable any more. It is thus urgent to think about agroecological solutions allowing to restore the biological balances, to maintain good soil quality and optimal plantain cropping systems.This is the ultimate goal of this thesis which couples the realization of an agroecological diagnosis in peasants’ plots, and the test of agroecological alternatives in semi-controlled conditions. To do this, a typology of plantain cropping systems was carried out from an agrienvironmental survey in the two study areas. It allowed to select 23 plots in Guadeloupe and 12 in Haiti in which an agroecological diagnosis was implemented. Based on this diagnosis and the research of agroecological alternatives to the use of chemicals, a field experiment was set up in Guadeloupe, in an experimental station allowing the test of three innovative practices for plantain cultivation (alone and combined), namely : i) the introduction of a cover-crop Paspalum notatum for weed control while reducing the use of herbicides ; ii) the input of worms’ compost to control plant-parasitic nematodes specific to plantain and to fertilize it ; iii) the use of healthy “PIF” plants (plants issued from stem fragments) free from telluric pests (nematodes and weevil’s larvaes).The typology of plantains cropping systems shows: i) in Guadeloupe the previous crops are: fallow pineapple and plantain predominate with a low level of intensification (low and infrequent chemical inputs) or high (high and frequent chemical inputs); ii) in Haiti, the previous crops are: fallow, plantain and cassava predominate with a low level or no intensification at all (no inputs). The results of the agroecological analysis show that : i) when the level of intensification is low, perennial plantain and pineapple as previous crops help maintaining a good soil quality and a good regulation of the telluric pests ; ii) when the level of intensification is strong, the soil engineers drastically reduce, while the density of telluric parasites increases without affecting good levels of instantaneous yields (plots where the previous crop is pineapple or mostly fallow) ; iii) when the fertilization is totally missing, it decreases the biological activity of the soil furthermore the plantain yields, exacerbated by the choice of the previous crop (cassava or plantain), in connection with soils and climate constraints and the black Sigatoka caused by Mycosphaerella fijiensis, especially in the Haitian plots ; iv) the crop succession plantain/plantain is the most critical regarding the plantain’s cropping, because whatever the level of intensification, the yields remain relatively low in connection with a degradation of the health state, compared to other previous crops.The driving of an experiment in a research station shows that on the scale of one year, the three tested innovative practices allow maintaining a good soils quality. Healthy plants "PIF" have a better health state (absence of plant parasitic nematodes in the roots) which helps a significant increase of the yields. Cover-crop P. notatum helps the weeds and the soil pests control and favors the improvement of soil biological activity and plantain yields. Worms’ compost contributes to the maintenance of a better soils quality while allowing the regulation of the populations of plant-parasitic nematodes of the plantains.

http://www.theses.fr/2014AGUY0758/document

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
Background. An association with cancer is described in 17–32% of cases of dermatomyositis (DM) and in 5–16% of cases of anti-synthetase syndrome (ASS). The literature contains very few studies involving Afro-Caribbean patients with DM or ASS. The aim of our retrospective study was to determine the prevalence of cancer in a series of patients with DM or ASS at the University Hospital of Pointe-à-Pitre between 1st January 2000 and 31st December 2012. The secondary objective was to review the clinical and laboratory features as well as the course of DM/ASS in these patients.Patients and methods. The inclusion criteria were as follows: Afro-Caribbean origin; age >15 years; patient living in Guadeloupe; screening for malignancy.Results. Twenty-two patients were included (15 DM, 7 ASS). Only one case of cancer was diagnosed in the entire study population at a mean follow-up of 6±4 years (prevalence: 6.7%, CI95% [1.7–31.9]). Of the 15 patients presenting DM (sex ratio F/M: 4, mean age: 45±14 years), 6 (40%) had associated connective tissue disease.Conclusion. Our study suggests a weak association between DM and cancer in Afro-Caribbean patients. These results may be explained by the features of the disease seen in these patients (female gender, young age at onset, associated connective tissue disease) and the low prevalence in the Caribbean region of cancers typically associated with DM.
Introduction. Dix-sept à 32 % des cas de dermatomyosite (DM) et 5 à 16 % des cas de syndrome des anti-synthétases (SAS) sont associés à un cancer. Les séries de patients afro-caribéens atteints de DM ou de SAS sont exceptionnellement rapportées dans la littérature. Le but de notre étude rétrospective était d’estimer la prévalence des cancers dans une série de patients guadeloupéens atteints de DM ou de SAS. L’objectif secondaire était de préciser les caractéristiques cliniques, biologiques et évolutives de la maladie chez ces patients.Patients et méthode. Les critères d’inclusion étaient les suivants : patient afro-caribéen ; âge >15ans ; patient vivant en Guadeloupe ; réalisation d’un bilan d’extension à la recherche d’une néoplasie.Résultats. Vingt-deux patients ont été inclus (15 atteints de DM, 7 de SAS). Un seul cancer a été diagnostiqué, avec une durée moyenne de suivi de 6±4ans sur l’ensemble de la série (prévalence de 6,7 % ; IC 95 % [1,7 ; 31,9]). Parmi les 15 patients atteints de DM (sex-ratio H/F=1/4 ; âge moyen : 45±14ans), 6 (40 %) avaient une connectivite associée.Conclusion. Notre étude suggère une faible association entre DM et cancer chez les patients afro-caribéens. Ces résultats s’expliquent principalement par les caractéristiques de la maladie chez ces patients (sexe féminin, jeune âge, connectivite associée) et la faible prévalence, aux Antilles, des cancers classiquement associés aux DM.
ISSN: 0151-9638

inserm-01110999
http://www.hal.inserm.fr/inserm-01110999
http://www.hal.inserm.fr/inserm-01110999/document
http://www.hal.inserm.fr/inserm-01110999/file/2014%2C%20Tersiguel%20-%20Epid%C3%A9miologie%20de%20la%20dermatomyosite%20et%20du%20syndrome%20des%20anti-synth%C3%A9tases%20en%20population%20afro-carib%C3%A9enne.pdf
PUBMED : 25288059

Éditeur(s) : Wiley-blackwell
Résumé : In bird species that have a high movement capacity, dispersal may connect subpopulations over vast geographical regions, with important consequences for the design of conservation management strategies. Here we used a molecular approach to infer the patterns and rates of dispersal among eight Mediterranean subpopulations of the endangered Bonelli's Eagle, based on 245 individuals screened at 17 microsatellite loci. There was moderate genetic differentiation between subpopulations sampled in the western (Iberia and Morocco) and eastern (Cyprus) Mediterranean, whereas differentiation among subpopulations in the former region was weak to moderate and followed a pattern of isolation by distance. Within the western Mediterranean, the small, peripheral and ecologically unique population of southwest Portugal had the lowest genetic diversity and the highest differentiation. The remaining subpopulations formed two loose clusters, one including Morocco and southwest and eastern Spain, and the other northeast Portugal and western and central Spain. Few recent migrants were detected, and they originated primarily from adjacent subpopulations. Our findings suggest that western Mediterranean Bonelli's Eagles may have a large-scale metapopulation structure, with subpopulations connected to some extent by distance-dependent dispersal, probably influenced by natal philopatry and the geographical configuration of subpopulations. The combination of marked ecological and genetic divergence suggests that the peripheral subpopulation of southwest Portugal may be regarded as a distinct management unit.
Ibis (0019-1019) (Wiley-blackwell), 2013-07 , Vol. 155 , N. 3 , P. 485-498

Droits : 2013 British Ornithologists’ Union
http://archimer.ifremer.fr/doc/00148/25924/24018.pdf
DOI:10.1111/ibi.12065
http://archimer.ifremer.fr/doc/00148/25924/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Melt generation in the continental crust is thought to significantly influence seismic bulk velocities and anisotropy, although existing laboratory data provide limited constraints on such seismic attributes. In this study we measured ultrasonic compressional wave speeds (Vp) and anisotropy during sample compaction, mica-breakdown and melt-generation in synthetic, foliated quartz–muscovite aggregates. Measurements were performed at peak conditions of 300 MPa hydrostatic confining pressure and 750 °C, over a six hour time period, for three separate samples where wave propagation directions were aligned at 0°, 45° and 90° with respect to the foliation plane. The experiments are initially marked by sample compaction and rapid reduction in porosity (from 25% to <2 vol%), with a corresponding increase in Vp. During initial stages of the experiment Vp ranges from 4.65 to 5.45 km/s, depending on the direction of the P wave propagation, resulting in up to ∼16% anisotropy, which originates mainly from the preferred orientation of muscovite and possible incipient melt lenses oriented parallel to foliation. As the experiment progresses the bulk Vp decreases gradually and Vp anisotropy drops from ∼16% to ∼2% after five hours into the experiment. The drop in anisotropy is caused by muscovite-breakdown and increasing amount of partial melting of the aggregate. The bulk velocities are considerably lower than predicted for a mixture of muscovite and β-quartz (stable at 300 MPa and 750 °C). Thermodynamic modeling indicates that mica breakdown and production of melt with ∼2 wt% dissolved water in the aggregate can explain the low Vp, even though β-quartz is stable; the modeled Vp is ∼4.75 km/s at 300 MPa and 750 °C. These ultrasonic attributes signify movement of the melt to fill vacant pores and coating grain boundaries, effectively connecting melt films and reducing seismic anisotropy. The results may apply to regions where crustal melting is on-going, in particular regions of elevated temperature that are only weakly deforming, with coupled anomalously low bulk velocities and seismic anisotropy.
ISSN: 0012-821X

hal-01243569
https://hal.archives-ouvertes.fr/hal-01243569
DOI : 10.1016/j.epsl.2015.05.039

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This study provides an integrated review of plate tectonic models of the evolution of the Antarctica-Patagonia connection compared to geological records collected on land in Patagonia and Tierra del Fuego, and offshore along the northern edge of the Scotia Sea. A temporal framework for the sedimentary and tectonic events of the North Scotia Ridge and Tierra del Fuego is constructed with additional data compiled from entire Patagonia and the Austral Basin. This review provides robust correlations of seaways and tectonic events along the Scotia and South America plates and indicates that the opening of the Drake Passage was not steady state since ca. 30 Ma. Rather the regions forming the present-day northern limit of this gateway experienced important paleogeographic changes, from deep marine basins to shallow ridges and emerged regions during the late Oligocene and early-middle Miocene time. Our compilation of geological data shows that emergence along the North Scotia Ridge and Tierra del Fuego was achieved at 23-22 Ma, and has been followed by elimination of the Patagoniano Sea in Patagonia, starting at 22-23 Ma and achieved at 20 Ma. This transition towards more continental sedimentation in southern South America is correlated with more shallow marine conditions in the Austral Basin. This succession of events had a strong influence on the general geometry of the Drake Passage, corresponding to a constriction of its northern limit, starting in the window 29-22 Ma and achieved at 21 Ma. This period of active deformation in southern South America also corresponds to a period of the global climate having two anomalies well known from the isotopic records: the Late Oligocene Warming. around 26 Ma and the Mid-Miocene Climatic Optimum which ended between 15 and 14 Ma. The possible effects of the post-Oligocene tectonic evolution of the Drake Passage region on general oceanic circulation are discussed. Causes for the synchronicity between tectonic events and these global warming events are examined.
ISSN: 0012-821X

hal-00413525
https://hal.archives-ouvertes.fr/hal-00413525
DOI : 10.1016/j.epsl.2008.12.037

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : A preliminary version appeared in the 18th ACM-SIAM Symposium on Discrete Algorithms, pp. 746- 755, 2007
International audience
The Voronoi diagram of a finite set of objects is a fundamental geometric structure that subdivides the embedding space into regions, each region consisting of the points that are closer to a given object than to the others. We may define various variants of Voronoi diagrams depending on the class of objects, the distance function and the embedding space. In this paper, we investigate a framework for defining and building Voronoi diagrams for a broad class of distance functions called Bregman divergences. Bregman divergences include not only the traditional (squared) Euclidean distance but also various divergence measures based on entropic functions. Accordingly, Bregman Voronoi diagrams allow one to define information-theoretic Voronoi diagrams in sta- tistical parametric spaces based on the relative entropy of distributions. We define several types of Bregman diagrams, establish correspondences between those diagrams (using the Legendre transformation), and show how to compute them efficiently. We also introduce extensions of these diagrams, e.g. k-order and k-bag Bregman Voronoi diagrams, and introduce Bregman triangulations of a set of points and their connection with Bregman Voronoi diagrams. We show that these triangulations capture many of the properties of the celebrated Delaunay triangulation.
ISSN: 0179-5376

hal-00488441
https://hal.archives-ouvertes.fr/hal-00488441
https://hal.archives-ouvertes.fr/hal-00488441/document
https://hal.archives-ouvertes.fr/hal-00488441/file/BVD-DCG.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The marine Messinian deposits of Tunisia cover a narrow littoral strip some 300 km long between the northern Bizerte and Cap Bon areas and the central-eastern Sahel region. Litho- and biofacies analysis of six stratigraphic sections reveals the distinctive features of these deposits.;The lower Messinian deposits are characterized by ubiquitous siliciclastics and abundant oolitic/bioclastic limestones organized in an eastward facing ramp. Westward (landward), this ramp changes into coastal lagoons, sometimes containing evaporites. Eastward, the ramp passes to the reefal Pelagian Platform extending as far as Lampedusa.;Two main sedimentary cycles are distinguished: 1) an early Messinian siliciclastic retrogradational then oolitic/bioclastic progradational cycle (Beni Khiar Formation and lower Oued bel Khedim Formation): 2) a late Messinian brackish to continental cycle that probably accumulated in rapidly subsiding lagoons (Cued el Bir Formation and upper Oued bel Khedim Formation). The Tunisian early Messinian cycle is partly eustatically controlled, but the late Messinian cycle cannot be confidently correlated to other well-known Messinian series because of tectonic movements.;The lower Messinian deposits of Tunisia are also characterized by abundant suspension-feeding organisms (molluscs and bryozoans) and rare corals, calcareous algae, echinoids, and larger benthic foraminifers. The proposed palaeoenvironmental model shows that the lower Messinian ramp of Tunisia was located on a current-protected margin and subjected to continent-derived sediment and nutrient supply. Eastward, nutrient influx diminished and a shallow-water isolated carbonate platform with coralgal facies developed between the western and the eastern Mediterranean basins. The main hydrological connection between these two basins occurred through a narrow seaway situated to the northeast of the Pelagian Platform, south of Sicily and Malta.
ISSN: 0031-0182

hal-00475583
https://hal.archives-ouvertes.fr/hal-00475583
DOI : 10.1016/j.palaeo.2009.10.028

Éditeur(s) : Wiley-blackwell
Résumé : The history of colonization and dispersal in fauna distributed among deep-sea chemosynthetic ecosystems remains enigmatic and poorly understood because of an inability to mark and track individuals. A combination of molecular, morphological and environmental data improves understanding of spatial and temporal scales at which panmixia, disruption of gene flow or even speciation may occur. Vestimentiferan tubeworms of the genus Escarpia are important components of deep -sea cold seep ecosystems, as they provide long-term habitat for many other taxa. Three species of Escarpia, Escarpia spicata [Gulf of California (GoC)], Escarpia laminata [Gulf of Mexico (GoM)] and Escarpia southwardae (West African Cold Seeps), have been described based on morphology, but are not discriminated through the use of mitochondrial markers (cytochrome oxidase subunit 1; large ribosomal subunit rDNA, 16S; cytochrome b). Here, we also sequenced the exon-primed intron-crossing Haemoglobin subunit B2 intron and genotyped 28 microsatellites to (i) determine the level of genetic differentiation, if any, among the three geographically separated entities and (ii) identify possible population structure at the regional scale within the GoM and West Africa. Results at the global scale support the occurrence of three genetically distinct groups. At the regional scale among eight sampling sites of E. laminata (n=129) and among three sampling sites of E. southwardae (n=80), no population structure was detected. These findings suggest that despite the patchiness and isolation of seep habitats, connectivity is high on regional scales.
Molecular Ecology (0962-1083) (Wiley-blackwell), 2013-08 , Vol. 22 , N. 16 , P. 4147-4162

Droits : 2013 John Wiley & Sons Ltd
http://archimer.ifremer.fr/doc/00152/26354/24515.pdf
DOI:10.1111/mec.12379
http://archimer.ifremer.fr/doc/00152/26354/