Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Cross-species analyses of plant functional traits have shed light on factors contributing to differences in performance and distribution, but to date most studies have focused on either leaves or stems. We extend these tissue-specific analyses of functional strategy towards a whole-plant approach by integrating data on functional traits for 13 448 leaves and wood tissues from 4672 trees representing 668 species of Neotropical trees. Strong correlations amongst traits previously defined as the leaf economics spectrum reflect a tradeoff between investments in productive leaves with rapid turnover vs. costly physical leaf structure with a long revenue stream. A second axis of variation, the 'stem economics spectrum', defines a similar tradeoff at the stem level: dense wood vs. high wood water content and thick bark. Most importantly, these two axes are orthogonal, suggesting that tradeoffs operate independently at the leaf and at the stem levels. By simplifying the multivariate ecological strategies of tropical trees into positions along these two spectra, our results provide a basis to improve global vegetation models predicting responses of tropical forests to global change.
ISSN: 1461-023X

hal-00594040
https://hal.archives-ouvertes.fr/hal-00594040

Éditeur(s) : Gauthier-Villars
Résumé : The Mazagan (El Jadida) plateau and escarpment constitute the seaward extension of the Moroccan Meseta. Sedimentary sequence began at least as long ago as the Triassic. A very dense seismic reflection survey (32 profiles at 1 n. mile spacing) and information from 18 Cyana dives on the Mazagan the construction of isochrom map of the depth of the acoustic basement constituted either by jurassic platform carbonates or by Paleozoic granodiorite to Precambrian (?) crystalline basement, and a detailed structural map. The carbonate platform is structured in a succession of tilted blocks from the plateau to the foot of the escarpment. During early Cretaceous times, an important phase of vertical structuration is marked by the denudation of the escarpment. Transgressive sediments of late Cretaceous age cover unconformably the carbonate platform along the outer edge of the Mazagan Plateau. Deformation observed within the sedimentary cover suggests vertical tectonism from late Cretaceous up to the Present.
Oceanologica Acta, Special issue (0399-1784) (Gauthier-Villars), 1985

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00247/35832/34342.pdf
http://archimer.ifremer.fr/doc/00247/35832/

Éditeur(s) : Proceedings of the 9th International Pectinid Workshop, Canada
Résumé : The influence of density on Patinopecten yessoensis larval development was studied during production of an F2 generation. Setting behaviour of P. yessoensis on PVC removable spat collectors, previously tested with Pecten maximus, was determined. Poor larval growth of P. yessoensis was observed at a larval density of 7 ·ml·1 and post larval settlement occurred mainly on the bottom of the baskets, as has been observed with the king scallop, P. maximus. The PVC collector is not suitable for either species of scallop.

Droits : 1994 Ifremer
http://archimer.ifremer.fr/doc/00090/20163/17816.pdf
http://archimer.ifremer.fr/doc/00090/20163/

Éditeur(s) : HAL CCSD
Résumé : The presence of biological matter (biofilms) in deep geological sites for storage of, for instance, toxic elements or groundwater in aquifers was clearly proved. That biomass triggers physical and chemical processes which greatly modify the durability and the sustainability of the sites. These processes, mainly from oxidative/reductive reactions, are poorly understood. This is mainly due to the fact that former studies were done at the macroscopic level far away from the micrometric scale where relevant processes induced by bacteria take place. Investigations at microscopic level are needed. Thus, we developed an experimental set-up based on the combined use of optical microscopy (transmission), atomic force microscopy (AFM) and electrical and electro-chemical AFM microscopy (EC_AFM) in order to get simultaneous information on topographic and electro-chemical processes. The first highly sensitive step was to use AFM with biological samples in liquid environment: wepresent here a study about AFM imaging of living, moving or self-immobilized bacteria, in their genuine physiological liquid medium and in true in vivo conditions. No external immobilization protocol, neither chemical nor mechanical was needed. For the first time, the native gliding movements of Gram negative Nostoc cyanobacteria upon the surface were studied by AFM. AFM height and mechanical stiffness data were simultaneously acquired. From these, mechanical parameters, inner turgor pressure and Young modulus, were derived for different bacterial species (Anabaenopsis circularis, Rhodococcus wratislaviensis). Our study revealed that AFM imaging is thus possible on moving living species. These results open a large window on new studies of both dynamical phenomena of practical and fundamental interests such as the formation of biofilms and dynamic properties of bacteria in real physiological conditions. The second delicate step was to combine AFM and optical measurements with electrical ones. We mounted a new experimental set-up coupling real-time (i) monitoring of optical properties as the optical density (OD) evolution related to bulk bacterial growth in liquid or as the counting of number of bacteria adhering on the surface of the sample as well and (ii) electrical and electrochemical measurements. Furthermore, these results will shortly be applied to the optimized monitoring of the in-situ activity of bacteria consuming oil pollutants, following this way, in real-time, the bioremediation of an oilcontaminated soil (ANR ECOTECH_BIOPHY program).
La présence de matière biologique (biofilms) dans les sites de stockage géologique profond, d'éléments toxiques ou encore de l'eau potable des aquifères est maintenant clairement démontrée. Cette biomasse est à l'origine de processus physiques et chimiques qui modifient considérablement la durabilité et la pérennité des sites concernés. Ces processus, principalement de type oxydo-réductif, sont encore mal compris. Ceci est principalement dû aux méthodes d'investigation, principalement macroscopiques, loin de l'échelle micrométrique caractéristique des bactéries. Seules des études, basées sur des méthodes d'investigation locale, peuvent apporter les informations requises. Ainsi, nous avons développé un dispositif expérimental basé sur l'utilisation combinée de la microscopie optique (en transmission), la microscopie à force atomique (AFM) et la microscopie AFM en mode électrique et électrochimique (EC_AFM) afin d'obtenir des informations simultanées sur la topographie de l'échantillon et sur les processus électrochimiques à l'échelle des bactéries. La première étape sensible consistait à utiliser l'AFM sur des échantillons biologiques en milieu liquide: nous présentons ici les résultats de l'imagerie AFM en milieu liquide de plusieurs types de bactéries dans leurs conditions physiologiques naturelles (conditions in vivo). Aucun protocole d'immobilisation, ni chimique ni mécanique, n'a été nécessaire; et pour la première fois, les mouvements de reptation de cyanobactéries Nostoc ont été étudiés par l'AFM. Les études AFM ont permis d'acquérir des données topographiques mais aussi mécaniques : nous avons pu ainsi mesurer le module d'Young, la pression de turgescence de différentes souches bactériennes (Anabaenopsis circularis, Rhodococcus wratislaviensis). Cette étude complète, a révélé que l'imagerie AFM est donc possible sur des espèces vivantes en mouvement. Ces résultats ouvrent une grande fenêtre sur de nouvelles études d'intérêts tels que la formation de biofilms et les propriétés dynamiques de bactéries dans des conditions physiologiques réelles. La deuxième étape délicate était de combiner l'AFM aux mesures optiques et électriques. Nous avons développé un nouveau dispositif expérimental permettant (i) le suivi de l'évolution de la croissance bactérienne par la mesure des propriétés optiques comme la densité optique DO (pour le développement bactérien en volume - milieu planctonique) , ou l'analyse de l'image du substrat par comptage du nombre de bactéries sur la surface de l'échantillon (biofilm), et (ii) les mesures électriques et électrochimiques. L'ensemble de ces résultats sera prochainement appliqué au développement de nouveaux outils de surveillance d'une biodépollution de terrain contaminé par les hydrocarbures, par le suivi in situ et en temps réel de l'activité de bactéries dépolluantes (ECOTECH_BIOPHY ANR).
https://tel.archives-ouvertes.fr/tel-01044714

tel-01044714
https://tel.archives-ouvertes.fr/tel-01044714
https://tel.archives-ouvertes.fr/tel-01044714/document
https://tel.archives-ouvertes.fr/tel-01044714/file/theseDhahri2013.pdf

Éditeur(s) : Elsevier
Résumé : The multi-component aspect of species diversity of groundfish assemblages was examined on the basis of a set of experimental trawl surveys conducted on the east coast of Corsica. We analysed and compared the structuration of diversity within three different bathymetric strata: the continental shelf (60-120 m depth), the upper slope (250-400 m) and the lower slope (450-570 m). For each of these three bathymetric strata, we simultaneously analysed 12 indices that are theoretically complementary and relate to 4 diversity components: (1) the number of species, (2) rarity, (3) evenness and (4) taxonomic diversity. Principal component analysis based on Spearman's correlation coefficients was carried out to investigate empirical relationships between the selected indices. Our results showed not only that a single diversity index cannot provide a complete view of the groundfish diversity along the east coast of Corsica, but also that-in some cases-one index cannot even encapsulate a complete description of a specific diversity component. We also found that the nature and the number of independent diversity components slightly varied from one bathymetric stratum to another. The main differences-which mainly occurred in the deepest bathymetric stratum-might be associated with lower density of individuals and lower dominance of some species at deeper depths. Finally, this study is the first dealing with groundfish diversity in this area, which is currently characterized by one of the lowest fishing intensity rates in the northern Mediterranean Sea. It might be considered as a first '' reference state '' with a view to monitoring the spatio-temporal changes in species diversity patterns along the east coast of Corsica in the future. (C) 2007 Elsevier B.V. All rights reserved.
Fisheries Research (0165-7836) (Elsevier), 2007-12 , Vol. 88 , N. 1-3 , P. 120-132

Droits : 2007 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2007/publication-3512.pdf
DOI:10.1016/j.fishres.2007.08.003
http://archimer.ifremer.fr/doc/00000/3512/

Éditeur(s) : HAL CCSD Oxford University Press (OUP): Policy F
Résumé : International audience
We discuss a property of distance-based measures that has not been addressed with regard to evaluating the geographic concentration of economic activities. The article focuses on the choice between a probability density function of point-pair distances or a cumulative function. We begin by introducing a new cumulative function, M, for evaluating the relative geographic concentration and the co-location of industries in a non-homogeneous spatial framework. Secondly, some rigorous comparisons are made with the leading probability density function of Duranton and Overman (2005), Kd. The merits of the simultaneous use of Kd and M is proved, underlining the complementary nature of the results they provide.
Journal of Economic Geography

hal-01094082
https://hal-agroparistech.archives-ouvertes.fr/hal-01094082
DOI : 10.1093/jeg/lbp056

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
LiDAR (Light Detection And Ranging) remote sensing has been shown to be a good technique for the estimation of forest parameters such as canopy heights and above ground biomass. Whilst airborne LiDAR data are in general very dense but only available over small areas due to the cost of their acquisition, spaceborne LiDAR data acquired from the Geoscience Laser Altimeter System (GLAS) have a coarser acquisition density associated with a global cover. It is therefore valuable to analyze the integration relevance of canopy heights estimated from LiDAR sensors with ancillary data such as geological, meteorological, and phenological variables in order to propose a forest canopy height map with good precision and high spatial resolution.In this study, canopy heights extracted from both airborne and spaceborne LiDAR, were first extrapolated from available environmental data (e.g. geology, slope, vegetation indices, etc.). The estimated canopy height maps using random forest (RF) regression from the airborne or GLAS calibration datasets showed similar precisions (RMSE better than 6.5 m). In order to improve the precision of the canopy height estimates regression-kriging (kriging of random forest regression residuals) was used. Results indicated an improvement in the RMSE (decrease from 6.5 to 4.2 m) for the regression-kriging maps from the GLAS dataset, and from 5.8 to 1.8 m for the regression-kriging map from the airborne LiDAR dataset. Finally, in order to investigate the impact of the spatial sampling of future LiDAR missions on the precision of canopy height estimates, six subsets were derived from the initial airborne LiDAR dataset with flight line spacing of 5, 10, 20, 30, 40 and 50 km (corresponding to 0.29, 0.11, 0.08, 0.05, 0.04, and 0.03 points/km² respectively). Results indicated that using the regression-kriging approach achieved a precision of 1.8 m on the canopy height map with flight line spacing of 5 km and achieved an average RMSE of 4.8m for the configuration for the 50 km flight line spacing.
ISSN: 2072-4292

hal-01361343
https://hal.archives-ouvertes.fr/hal-01361343
https://hal.archives-ouvertes.fr/hal-01361343/document
https://hal.archives-ouvertes.fr/hal-01361343/file/mt2016-pub00048036.pdf
DOI : 10.3390/rs8030240

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
A dense, local network of 30 geodetic markers covering a 50 × 60 km2 area in the southwestern European Alps (Briançon region) has been temporarily surveyed in 1996, 2006 and 2011 by GPS. The aim is to measure the current deformation in this seismically active area. The study zone is characterized by a majority of extensional and dextral focal mechanisms, along north–south to N160 oriented faults. The combined analysis of the three measurement campaigns over 15 years and up to 16 years of permanent GPS data from the French RENAG network now enables to assess horizontal velocities below 1 mm/year within the local network. The long observation interval and the redundancy of the dense campaign network measurement help to constrain a significant local deformation pattern in the Briançon region, yielding an average E–W extension of 16 ± 11 nanostrain/year. We compare the geodetic deformation field to the seismic deformation rate cumulated over 37 years, and obtain good coherencies both in amplitude and direction. Moreover, the horizontal deformation localized in the Briançon region represents a major part of the Adriatic-European relative plate motion. However, the average uplift of the network in an extensional setting needs the presence of buoyancy forces in addition to plate tectonics.
ISSN: 0264-3707

hal-01119724
https://hal.archives-ouvertes.fr/hal-01119724
DOI : 10.1016/j.jog.2015.02.001

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Coral reefs are increasingly being altered by a myriad of anthropogenic activities and natural disturbances. Long-term studies offer unique opportunities to understand how multiple and recurrent disturbances can influence coral reef resilience and long-term dynamics. While the long-term dynamics of coral assemblages have been extensively documented, the long-term dynamics of coral reef fish assemblages have received less attention. Here, we describe the changes in fish assemblages on Tiahura reef, Moorea, from 1979 to 2011. During this 33-yr period, Tiahura was exposed to multiple disturbances (crown-of-thorns seastar outbreaks and cyclones) that caused recurrent declines and recoveries of coral cover and changes in the dominant coral genera. These shifts in coral composition were associated with long-term cascading effects on fish assemblages. The composition and trophic structure of fish assemblages continuously shifted without returning to their initial composition, whereas fish species richness remained stable, albeit with a small increase over time. We detected nonlinear responses of fish density when corals were most degraded. When coral cover dropped below 10 % following a severe crown-of-thorns sea star outbreak, the density of most fish trophic groups sharply decreased. Our study shows that historical contingency may potentially be an important but largely underestimated factor explaining the contemporary structure of reef fish assemblages and suggests that temporal stability in their structure and function should not necessarily be the target of management strategies that aim at increasing or maintaining coral reef resilience.
ISSN: 0722-4028

hal-01282725
https://hal-univ-perp.archives-ouvertes.fr/hal-01282725
DOI : 10.1007/s00338-015-1371-2

Éditeur(s) : HAL CCSD American Association for the Advancement of Science
Résumé : 6 pages
International audience
Large impacts provide a mechanism for resurfacing planets through mixing near-surface rocks with deeper material. Central peaks are formed from the dynamic uplift of rocks during crater formation. As crater size increases, central peaks transition to peak rings. Without samples, debate surrounds the mechanics of peak-ring formation and their depth of origin. Chicxulub is the only known impact structure on Earth with an unequivocal peak ring, but it is buried and only accessible through drilling. Expedition 364 sampled the Chicxulub peak ring, which we found was formed from uplifted, fractured, shocked, felsic basement rocks. The peak-ring rocks are cross-cut by dikes and shear zones and have an unusually low density and seismic velocity. Large impacts therefore generate vertical fluxes and increase porosity in planetary crust.
ISSN: 0036-8075

hal-01399386
https://hal.archives-ouvertes.fr/hal-01399386
PUBMED : 27856906
DOI : 10.1126/science.aah6561

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
We determine the elasticity of FeSiO3 perovskite for various spin configurations using density-functional theory calculations. The elastic moduli and the bulk seismic wave velocities are weakly affected by the spin transition. However we show that the intrinsic differences in seismic anisotropy between the high-spin and low-spin phases of Fe-bearing perovskite coupled with lattice preferred orientation that can develop due and during the convection may lead to distinct seismic signatures between the top and the bottom of the lower mantle. These signatures should be detectable in observations and they need to be taken into account in tomographic studies of the Earth's lower mantle.
ISSN: 0094-8276

hal-00512662
https://hal.archives-ouvertes.fr/hal-00512662
DOI : 10.1029/2010GL043320

Éditeur(s) : HAL CCSD Frontiers Media
Résumé : International audience
We present high resolution observations of microstructure and texture evolution during dynamic recrystallization (DRX) of ice polycrystals deformed in the laboratory at high temperature (≈0.98Tm). Ice possesses a significant viscoplastic anisotropy that induces strong strain heterogeneities, which result in an early occurrence of DRX mechanisms. It is therefore a model material to explore these mechanisms. High resolution c-axis measurements at sample scale by optical techniques and full crystallographic orientation measurements by cryo-Electron Back Scattering Diffraction (EBSD) provide a solid database for analyzing the relative impact of the macroscopic imposed stress vs. the local and internal stress fields on DRX mechanisms. Analysis of misorientation gradients in the EBSD data highlights a heterogeneous dislocation distribution, which is quantified by the Nye tensor estimation. Joint analyses of the dislocation density maps and microstructural observations highlight spatial correlation between high dislocation density sites and the onset of nucleation taking place by grain-boundary bulging, subgrain rotation or by the formation of kink-bands.
ISSN: 2296-6463

hal-01515284
https://hal.univ-lorraine.fr/hal-01515284
DOI : 10.3389/feart.2015.00081

Éditeur(s) : HAL CCSD
Résumé : One of the major challenges in forest ecology is to understand the ecology, physiology and potential responses of the> 250000 species of vascular plants of the planet through the categorization of this diversity into functional groups. This approach is essentially based on functional traits analysis, but few investigations were made in tropical areas. The aim of this study was to determine functional groups in two contrasted tropical ecosystems, dry (DF) and mountain rain (MRF) forest (respectively rainfall of 1 200 mm/year and 10 000 mm/year). Guadeloupe Island in FWI presents both these ecosystems spread over less 100 km. In a first time, we developed an original species typology based on 7 "soft" traits, easy to measure (stomatal density, leaf trichom density, chlorophyll content, leaf nitrogen content, specific leaf area, wood density, leaf area, plant height). The method was based on principal component analysis (PCA) and agglomerative hierarchical clustering (AHC) applied to these traits measured at the individual level (Blazy et al., 2009). In a second time, we evaluated the relevance of these soft trait-based groups compared to a typology based on 5 "hard" ecophysiological traits, more costly to quantify but with higher functional significance (difference between predawn and minimum leaf water potential, stomatal conductance, maximal carbon assimilation rate, leaf water potential at 90% of loss of stem hydraulic conductivity). When performed on the dominant canopy species in DF and MRF (a total of 13 species and 60 mature individuals), the typological approach based on soft traits seems relevant to discriminate groups with a distinct functional reality. Through both ecosystems, we obtained 4 homogenous groups. Two were exclusively composed by DF's or MRF's species, indicating that a functional strategy can be linked to specific environmental conditions. The two other groups showed a mix of DF and MRF species indicating that different functional strategies can coexist in the same environment. These mixed groups seem distinct by their ecophysiological features, particularly in term of hydraulic characteristics. One group was composed by drought tolerant species, water spender species, with a high xylem embolism resistance, whereas the second one was composed by water saver species, less resistant to embolism. Therefore, a determination of functional groups based on soft traits could be useful to model ecosystem's responses to environmental changes on a global scale.
Book of Abstracts - isem 2013 - Ecological Modelling for Ecosystem Sustainability
Toulouse, France

hal-00964668
https://hal.archives-ouvertes.fr/hal-00964668

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Background and AimsEpiphytism imposes physiological constraints resulting from the lack of access to the nutrient sources available to ground-rooted plants. A conspicuous adaptation in response to that lack is the phytotelm (plant-held waters) of tank-bromeliad species that are often nutrient-rich. Associations with terrestrial invertebrates also result in higher plant nutrient acquisition. Assuming that tank-bromeliads rely on reservoir-assisted nutrition, it was hypothesized that the dual association with mutualistic ants and the phytotelm food web provides greater nutritional benefits to the plant compared with those bromeliads involved in only one of these two associations.MethodsQuantitative (water volume, amount of fine particulate organic matter, predator/prey ratio, algal density) and qualitative variables (ant-association and photosynthetic pathways) were compared for eight tank- and one tankless-bromeliad morphospecies from French Guiana. An analysis was also made of which of these variables affect nitrogen acquisition (leaf N and δ(15)N).Key ResultsAll variables were significantly different between tank-bromeliad species. Leaf N concentrations and leaf δ(15)N were both positively correlated with the presence of mutualistic ants. The amount of fine particulate organic matter and predator/prey ratio had a positive and negative effect on leaf δ(15)N, respectively. Water volume was positively correlated with leaf N concentration whereas algal density was negatively correlated. Finally, the photosynthetic pathway (C3 vs. CAM) was positively correlated with leaf N concentration with a slightly higher N concentration for C3-Tillandsioideae compared with CAM-Bromelioideae.ConclusionsThe study suggests that some of the differences in N nutrition between bromeliad species can be explained by the presence of mutualistic ants. From a nutritional standpoint, it is more advantageous for a bromeliad to use myrmecotrophy via its roots than to use carnivory via its tank. The results highlight a gap in our knowledge of the reciprocal interactions between bromeliads and the various trophic levels (from bacteria to large metazoan predators) that intervene in reservoir-assisted nutrition.
ISSN: 0305-7364

hal-00849045
https://hal.archives-ouvertes.fr/hal-00849045
DOI : 10.1093/aob/mct147
PUBMED : 23864002

Éditeur(s) : HAL CCSD Intech
Résumé : International audience
The massive integration of sustainable energies into electrical grids (non-interconnectedor connected) is a major problem due to their stochastic character revealed by strongfluctuations at all scales. In this paper, the scaling behaviour or power law correlationsand the nature of scaling behaviour of sustainable resource data such as flow velocity,atmospheric wind speed, solar global solar radiation and sustainable energy such as,wind power output, are highlighted. For the first time, Fourier power spectral densitiesare estimated for each dataset. We show that the power spectrum densities obtained areclose to the 5/3 Kolmogorov spectrum. Furthermore, the multifractal and intermittentproperties of sustainable resource and energy data have been revealed by the concavityof the scaling exponent function. The proposed analysis frame allows a full descriptionof fluctuations of processes considered. A good knowledge of the dynamic of fluctua-tions is crucial to management of the integration of sustainable energies into a grid.
Sustainable Energy - Technological Issues, Applications and Case Studies

hal-01528087
https://hal.archives-ouvertes.fr/hal-01528087
DOI : 10.5772/106341

Éditeur(s) : HAL CCSD American Society for Investigative Pathology
Résumé : International audience
Based on both experimental and clinical data, tamoxifen has been proposed to have cardiovascular benefits, although the mechanism(s) contributing to that protective effect are still poorly understood. In vitro experiments demonstrated that tamoxifen elicits its transcriptional effect through estrogen receptor (ER) α, but other targets can participate in its actions. However, although tamoxifen selectively activates the activating function (AF)-1 of ERα, we recently showed that this ERα subfunction is dispensable for the atheroprotective action of 17β-estradiol (E2), the main ligand of ERs. The goal of the present work is to determine to which extent ERα and its AF-1 mediate the vasculoprotective action of tamoxifen. Our data confirm that tamoxifen exerts an atheroprotective action on low density lipoprotein receptor (LDL-r(-/-)) female mice, but, in contrast to E2, it fails to accelerate reendothelialization after carotid electric injury. Tamoxifen and E2 elicit differences in gene expression profiles in the mouse aorta. Finally, the atheroprotective action of tamoxifen is abrogated in ERα(-/-)LDL-r(-/-) mice and in LDL-r(-/-) mice selectively deficient in ERαAF-1 (ERαAF-1(0/0)LDL-r(-/-)). Our results demonstrate, for the first time to our knowledge, that tamoxifen mediates its actions in vivo through the selective activation of ERαAF-1, which is sufficient to prevent atheroma, but not to accelerate endothelial healing.
ISSN: 0002-9440

hal-00874317
https://hal.archives-ouvertes.fr/hal-00874317
DOI : 10.1016/j.ajpath.2013.03.010
PUBMED : 23669343

Éditeur(s) : HAL CCSD
Résumé : International audience
The presence of photosynthetic zooxanthellae (dinoflagellates) in the tissue of many cnidarians is the main reason for their ecological success (i.e. coral reefs). It could also be the main cause of their demise, as the worldwide bleaching of reef-building coral is nothing less than the breakdown of this symbiotic association. The stability of this relationship is the principal marker for the biomonitoring of cnidarian health. We have therefore developed a new, simple method to isolate zooxanthellae in a few steps using NaOH solution. The protocol was validated in three symbiotic cnidarian species: a sea anemone, a gorgonian and a coral. Our method allows the isolation of intact and viable zooxanthellae with better yields than classic methods, especially for species with a calcareous skeleton. Moreover, the isolated zooxanthellae were free of host nucleic contaminants, facilitating subsequent specific molecular analyses.
Journal of Experimental Biology

hal-01546180
https://hal.archives-ouvertes.fr/hal-01546180
DOI : 10.1242/jeb.074955

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : Approximately 4,000 petroleum (oil and gas) platforms exist in the northern Gulf of Mexico and form one of the world's most extensive de facto artificial reef systems. Collectively, these structures may comprise one of the largest fad (Fish Aggregating Device) arrays in the world, attracting surface and midwater pelagic fishes. The diverse composition of pelagic fish fauna at ngom platforms is described and includes valued species such as Thunnus albacares, Thunnus atlanticus, Coryphaena hippurus, Acanthocybium solandri, Rachycentron canadum, Seriola dumerili, Scomberomorus cavalla, and Decapterus punctatus. Petroleum platforms influence pelagic fishery resources and are an important component of the Gulf's commercial and recreational fishing industries. Reviewed literature revealed a sparsity of fundamental knowledge of densities, temporal and spatial occurrence, and fishing effort/catch rates of pelagic fishes at platforms. The role of Gulf petroleum platforms "as fads" is examined, possible mechanisms for aggregation are reviewed, and a synopsis of the author's preliminary findings on life history aspects of A. solandri and R. canadum from platforms is presented. It is proposed that platforms provide opportunities for the study of pelagic species to better understand the life history, ecology, behaviour, and habitat requirements of pelagic fishery resources in the Gulf of Mexico.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15301/12633.pdf
http://archimer.ifremer.fr/doc/00042/15301/

Résumé : Au cours de 325 relevés, 518 observations visuelles et 202 acoustiques ont permis de recenser 4 familles, 14 genres et 17 espèces, représentant un effectif total cumulé de près de 6000 cétacés contactés dans les limites de 15 mille nautiques des côtes en Guadeloupe. Les dauphins (Delphinidëe), constituent 33% des 36 espèces actuellement connues dans le monde. Six espèces plus rares ont été décrites. Parmi les cétacés à fanons, la baleine à bosse (Megaptera novaeangliae) migre dans les eaux côtières de décembre à fin mai et reste l'espèce la plus rencontrée. Grâce à un suivi individuel par télémétrie, il a pu être prouvé qu'au moins un individu de cette espèce pouvait séjourner dans l'archipel plus de huit jours. En 2010, une baleine à bosse de la baie du Moule à été suivie sur plus de 6300 kilomètres jusqu'au sud de l'Islande, vers les Iles Féroé. Une première estimation de stock sur la période de 2008 à 2011 propose que 442 baleines à bosse %CV 19,29 IC95% [302-645] évolueraient dans l'archipel côtier. Les carnïvores sont les plus abondants, avec parmi ceux-ci, le dauphin tacheté pantroplcal (Stenella attenuata) dont l'estimation indique que 270 à 300 individus évolueraient sur 1361 km2 avec une densité relative élevée (0,052 tndtvtdus/km>, %CV 90,16), principalement en-côte-sous-le-vent. L'analyse de la répartition spatiale et des facteurs du milieu indique une sectorisation géographique marquée des populations en zone côtière, avec des distributions influencées spécifiquement par la bathymétrie, la latitude, les distances à la côte et à l'isobathe 200, pour les informations principales et selon les espèces.
In 325 surveys, 518 visuai observations and acoustic 202 have identified four families, 14 genera and 17 species, representing a cumulative total ofnearly 6000 cetaceans assessed within 15 miles of coastal water ofGuadeloupe. Dolphins (Delphinidae), constitute 33% ofthe 36 species currently known in the world. Six rare species have been described. Among the baleen whales, the humpback whale (Megaptera novaeangliae) migrate into coastal waters from December to late May and is the species most encountered. With individual monitoring by telemetry, it has been proved that at least one individual ofthis species could stay in the archipelago over eight days. In 2010, a humpback whale in the Bay ofmold were followed for more than 6300 km to the south ofIceland to the Faroe Islands. A first estimate ofstock over the period 2008 to 20 Il suggests that 442 humpback whales CV% 19.2995% [302-645] would evolve in the coastal archipelago. <..';:-.'") Carnivores are the most abundant, with among them, the spotted dolphin (Stenella attenuata) whose estimate indicates that 270 to 300 individuals are present over 1361 km 2 with a high specifie density (0.052 individuals / km 2,% CV 90, 16), mainly in the Leeward coast. The analysis ofthe spatial distribution and environmental factors indicates a marked geographical sectorisation ofpopulations in coastal areas, with distributions specifically influenced by bathymetry, latitude, distance to the coast and the isobath 200, depending on the species

http://www.theses.fr/2012AGUY0520/document

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

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