Éditeur(s) : HAL CCSD Elsevier
Résumé : Extracting and purifying a representative fraction of bacteria from soil is necessary for the application of many techniques of microbial ecology. Here the influence of different soil types on the quantitative and qualitative recovery of bacteria by soil grinding and Nycodenz density gradient centrifugation was investigated. Three soils presenting contrasted physicochemical characteristics were used for this study. For each soil, the total (AODC: acridine orange direct count) and culturable (cfu: colony-forming units) bacterial densities were measured in three distinct fractions: (i) the primary soil, (ii) the soil pellet (soil remaining after centrifugation), and (iii) the extracted cells. The automated-ribosomal intergenic spacer analysis (A-RISA) was used to characterize the community structure directly from the DNA extracted from each fraction. The physicochemical characteristics of soils were found to influence both the efficiency of bacterial cell recovery and the representativeness of the extracted cells in term of community structures between the different fractions. Surprisingly, the most representative extracted cells were obtained from the soil exhibiting the lowest efficiency of cell recovery. Our results demonstrated that quantitative and qualitative cell recovery using Nycodenz density gradient centrifugation are not necessarily related and could be differentially biased according to soil type.
ISSN: 1164-5563

hal-01031904
https://hal.archives-ouvertes.fr/hal-01031904
DOI : 10.1016/j.ejsobi.2005.08.003

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Variation of dead wood decay rates among tropical trees remains one source of uncertainty in global models of the carbon cycle. Taking advantage of a broad forest plot network surveyed for tree mortality over a 23-year period, we measured the remaining fraction of boles from 367 dead trees from 26 neotropical species widely varying in wood density (0.23–1.24 g cm-3) and tree circumference at death time (31.5–272.0 cm). We modeled decay rates within a Bayesian framework assuming a first order differential equation to model the decomposition process and tested for the effects of forest management (selective logging vs. unexploited), of mode of death (standing vs. downed) and of topographical levels (bottomlands vs. hillsides vs. hilltops) on wood decay rates. The general decay model predicts the observed remaining fraction of dead wood (R2 = 60%) with only two biological predictors: tree circumference at death time and wood specific density. Neither selective logging nor local topography had a differential effect on wood decay rates. Including the mode of death into the model revealed thatstanding dead trees decomposed faster than downed dead trees, but the gain of model accuracy remains rather marginal. Overall, these results suggest that the release of carbon from tropical dead trees to the atmosphere can be simply estimated using tree circumference at death time and wood density.
ISSN: 0029-8549

hal-01094187
https://hal-agroparistech.archives-ouvertes.fr/hal-01094187
DOI : 10.1007/s00442-010-1602-8

Résumé : Herbácea, suculenta, aromática, generalmente de menos de 1 m. Hojas ovadas, cuneadas u obtusas en el ápice, subcordadas en la base, márgenes crenados, pubescentes. Flores en racimos de 10 a 30 cm; cáliz tomentoso, labio superior oblongo; corola blanquecina, rosada o lila.
Herbacée succulente, aromatique, atteignant généralement moins de 1 m. Feuilles ovées, avec pointe obtuse, base subcordée, bords crénelés, pubescents. Fleurs en grappes de 10 à 30 cm; calice tomenteux, lèvre supérieure oblongue; corolle blanchâtre, rosée ou couleur lilas.
Perennial herb, 60-100 cm high,with soft thick-stems, succulent, hairy, aromatic.  Leaves blades, 2.5-4.5 x 2.5-4 cm, thick and soft, broadly ovate, truncate-subcordate at the base, apex obtuse to rounded, margins crenate, both surfaces densely pubescent with glands; inflorescence a raceme 10-30 cm long; flowers bilabiate, corolla 7-9 mm long, lilac to whitish.
Nativa de Asia tropical y Africa, cultivada en las zonas tropicales del mundo.
Originaire de l’;Asie tropicale et d’;Afrique, cultivée dans les zones tropicales du monde.
Native to tropical Asia and Africa, cultivated in tropical regions

http://www.tramil.net/fototeca/plant287

Résumé : Arbusto aromático, 1 a 2 m de alto, ramas largas mimbreadas, decumbentes y arraigantes, densamente puberulentas o estrigosas. Hojas opuestas o ternadas, brevemente pecioladas, de 2-6 (raro 9) cm de longitud y 1.2-4.5 cm de ancho, oblongas, arrugadas, festonadas, cubiertas con pelillos cortos y nervaduras prominentes. Inflorescencias en cabezuelas axilares globosas, cilíndricas en la fructificación. Brácteas ovadas, acuminadas, las inferiores mucronadas. Flores zigomorfas, cáliz de 1.5-1.7 mm de largo y acrescente a la madurez; corola morada con fauces amarillas y blancas, rosada o blanca de 4 a 5 mm de largo. Fruto obovoide de 3 mm de ancho.
Arbuste aromatique, de 1 à 2 m de haut, aux branches longues et flexibles, décombantes et s’enracinant spontanément, très pubérulentes ou rugueuses. Feuilles opposées ou par groupes de trois, à pétiole court, de 2-6 (rarement 9) cm de longueur et de 1,2-4,5 cm de large, oblongues, rugueuses, festonnées, couvertes de petits poils courts et de nervures proéminentes. Inflorescences sous forme de petites têtes axillaires arrondies, cylindriques lors de la fructification. Bractées ovées, acuminées, les plus basses étant mucronées. Fleurs zygomorphes, calice de 1,5-1,7 mm de long continuant à croître une fois arrivé à maturité; corolle violette avec coeur jaune et blanc, rosée ou blanche de 4 à 5 mm de long. Fruit ovoïde de 3 mm de large.
Aromatic shrub, 1 to 2 m in height, branches long, slender and flexible like willow stems (osier-like), decumbent, lower basal branches can become long rooting suckers, densely puberulent or strigose.  Leaves opposite or ternate, briefly petiolate, 2-6 (rarely 9) cm long and 1.2-4.5 cm wide, oblong, corrugate, crenate, covered with short small hairs (pubescent) and prominent veins.  Inflorescences in globose axillary heads, cylindrical upon fructification.  Bracts ovate, acuminate, the inferior ones mucronate.  Flowers zygomorphic; calyx 1.5-1.7 mm in length and accrescent when ripe; corolla purple with yellow and white fauces (the throat of a gamopetalous corolla), pink or white, 4 to 5 mm in length.  Fruit obovoid, 3 mm in diameter.
América tropical y subtropical.
Amérique tropicale et subtropicale.
Tropical and subtropical America.

http://www.tramil.net/fototecaplant211

Éditeur(s) : Public Library Science
Résumé : Estimating diversity and abundance of fish species is fundamental for understanding community structure and dynamics of coral reefs. When designing a sampling protocol, one crucial step is the choice of the most suitable sampling technique which is a compromise between the questions addressed, the available means and the precision required. The objective of this study is to compare the ability to sample reef fish communities at the same locations using two techniques based on the same stationary point count method: one using Underwater Visual Census (UVC) and the other rotating video (STAVIRO). UVC and STAVIRO observations were carried out on the exact same 26 points on the reef slope of an intermediate reef and the associated inner barrier reefs. STAVIRO systems were always deployed 30 min to 1 hour after UVC and set exactly at the same place. Our study shows that; (i) fish community observations by UVC and STAVIRO differed significantly; (ii) species richness and density of large species were not significantly different between techniques; (iii) species richness and density of small species were higher for UVC; (iv) density of fished species was higher for STAVIRO and (v) only UVC detected significant differences in fish assemblage structure across reef type at the spatial scale studied. We recommend that the two techniques should be used in a complementary way to survey a large area within a short period of time. UVC may census reef fish within complex habitats or in very shallow areas such as reef flat whereas STAVIRO would enable carrying out a large number of stations focused on large and diver-averse species, particularly in the areas not covered by UVC due to time and depth constraints. This methodology would considerably increase the spatial coverage and replication level of fish monitoring surveys.
Plos One (1932-6203) (Public Library Science), 2014-01 , Vol. 9 , N. 1 , P. -

Droits : 2014 Mallet et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
http://archimer.ifremer.fr/doc/00170/28132/26352.pdf
DOI:10.1371/journal.pone.0084344
http://archimer.ifremer.fr/doc/00170/28132/

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé :  
In this paper, we report a study of the mating system and gene flow of Symphonia globulifera, a hermaphroditic, mainly bird-pollinated tree species with a large geographic distribution in the tropical Americas and Africa.Using three microsatellites, we analysed 534 seeds of 28 open pollinated families and 164 adults at the experimental site 'Paracou' in French Guiana. We observed, compared to other tropical tree species, relatively high values for the effective number of alleles. Significant spatial genetic structure was detected, with trees at distances up to 150 m more genetically similar than expected at random. We estimated parameters of the mating system and gene flow by using the mixed mating model and the TwoGener approach. The estimated multilocus outcrossing rate, tm, was 0.920. A significant level of biparental inbreeding and a high proportion of full-sibs were estimated for the 28 seed arrays. We estimated mean pollen dispersal distances between 27 and 53 m according to the dispersal models used. Although the adult population density of S. globulifera in Paracou was relatively high, the joint estimation of pollen dispersal and density of reproductive trees gave effective density estimates of 1.6 and 1.3trees/ha. The parameters of the mating system and gene flow are discussed in the context of spatial genetic and demographic structures, flowering phenology and pollinator composition and behaviour.
ISSN: 0018-067X

hal-01032178
https://hal.archives-ouvertes.fr/hal-01032178
DOI : 10.1038/sj.hdy.6800560

Résumé : Hierba anual o perenne, erguida, de hasta 1.5 m, muy aromática. Hojas lanceoladas a elípticas, sinuado-dentadas, agudas, de hasta 13 cm, glandulosas. Flores en glomérulos densos o en espigas; sépalos 3 a 5, aovados; pétalos ausentes. Fruto pequeño dentro del cáliz con semillas negras.
Herbe annuelle ou bisannuelle, dressée, pouvant atteindre 1,5 m, très aromatique. Feuilles lancéolées à elliptiques, sinuo-dentées, aiguës, pouvant atteindre 13 cm, glanduleuses. Fleurs en glomérules denses ou en épis; 3 à 5 sépales, ovés; sans pétales. Petit fruit à l';intérieur du calice avec graines noires.
Bushy taprootedherb, erect, up to 1.5 m, highly aromaticwith a strong garlic-like smell. Lower leaves, sinuate-dentate, 5-8 cm x 1-2cm, upper leaves smaller with smooth margin; inflorescences are cymes, flowers clustered, greenish, perianth 1 mm long; fruit a utricle, seeds red-brown, smooth, ovoid 0.7-0.8 mm long.
Originaria de América, naturalizada en el Viejo Mundo, frecuentemente cultivada.
Originaire d';Amérique, naturalisée dans l';Ancien Monde, fréquemment cultivée.
Native to America, naturalized to the Old World, widely cultivated.

http://www.tramil.net/fototeca/plant120

Résumé : Hierba trepadora de hasta 6 m, usualmente muy ramificada. Hojas alternas de 4 a 12 cm, 5-7 lobadas; lóbulos obtusos o mucronulados con márgenes dentados o crenados. Corola amarilla, segmentos obtusos o emarginados de 1.5 a 2 cm. Fruto elipsoide, tuberculado, dehiscente, de 5 a 15 cm de diámetro, de amarillo a anaranjado, con 3 valvas; pulpa de color rojo; semillas elípticas, planas, de 10 a 16 mm.
Herbe grimpante pouvant atteindre 6 m, habituellement très ramifiée. Feuilles alternes de 4 à 12 cm, avec 5-7 lobes; lobes obtus ou mucronés, bords dentés ou crénelés. Corolle jaune, segments obtus ou émargés de 1,5 à 2 cm. Fruit ellipsoïdal, tuberculé, déhiscent, de 5 à 15 cm de diamètre, jaune à orangé, avec 3 valves; pulpe de couleur rouge; graines ellipsoïdales, aplaties, de 10 à 16 mm.
Climbing dioecious herb 6 m or more, usually densely branchedwith tendrils.  Leaves alternate, simple 4-12 cm long, deeply5-7 lobed,sinuate with mucronate tips; inflorescence a raceme; female and male flowers yellow, peduncle shorter on female flower, bracts on male peduncle reniform to rounded-cordate; fruit cylindrical, narrowed at both ends, 8-15 cm long, prominent tubercles on the ribs, orange when ripe containing pendulous seeds covered in a red pulp; seed oblong 12-16 mm x 5-9 mm and 3-4 mm thick.
Originaria del Viejo Mundo y naturalizada en todos los trópicos.
Originaire de l’;Ancien Monde et naturalisée sous tous les tropiques.
Native to the Old World and naturalized in all tropical regions.

http://www.tramil.net/fototeca/plant232

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The study of decay resistance in wood is of interest for wood end-users but also for the global carbon balance since wood biodegradation is a key driver of forest ecosystem functioning through its impacts on carbon and nutrient cycling. We studied the density and wood extractive contents in order to understand decay resistance against soil microflora after 90 days exposure of sapwood and heartwood from three Neotropical wood species known for their decay resistance: Bocoa prouacensis, Vouacapoua americana, Inga alba. Decay resistance was correlated with density more than wood extractive content. The results highlighted different decay resistance strategies. In B. prouacensis, both sapwood and heartwood were highly resistant due to the high density and high content of antifungal wood extractives. In V. americana heartwood, decay resistance was due to the high synergistic-acting wood extractive content. Conversely, with the least dense wood species I. alba, we found that decay resistance was due to the antifungal wood extractives synthesized early in the sapwood. In conclusion, we showed that the three wood species with the same level of heartwood decay resistance performance had different decay resistance strategies according to the anatomic and defensive wood traits.
ISSN: 0964-8305

hal-01321162
https://hal.archives-ouvertes.fr/hal-01321162
https://hal.archives-ouvertes.fr/hal-01321162/document
https://hal.archives-ouvertes.fr/hal-01321162/file/Art_Amusant_al_Diversity_decay_resistance_strategies_Int.Biodet.Biodegr._2014.pdf
DOI : 10.1016/j.ibiod.2014.06.012

Résumé : Arbol de hasta 18 m de alto. Hojas pecioladas, subcoriáceas, oblongo elípticas a lanceoladas, agudamente acuminadas, pinnado nervadas de hasta 13 cm de longitud. Inflorescencias estaminadas de 3 a 20 flores; las pistiladas usualmente de una sola flor; flores pequeñas, amarillo cremosas. Fruto piriforme o subgloboso (nuez) de hasta 5 cm, colgante, rojizo o amarillento, con dos valvas; semilla con arilo escarlata.
Arbre pouvant atteindre 18 m de haut. Feuilles pétiolées, presque coriaces, oblongo-elliptiques à lancéolées, terminées en pointe très fine, pennatinnervées pouvant atteindre 13 cm de long. Inflorescences staminées de 3 à 20 fleurs; celles qui sont pourvues d’un pistil ont habituellement une seule fleur; fleurs petites, jaunes-crèmes. Fruit piriforme ou presque arrondi pouvant atteindre 5 cm, tombant, rougeâtre ou jaunâtre, bivalve; graine avec arille écarlate.
Tree dioecious 6-18 m high with a dense crown and aromatic wood.  Leaves simple, alternate, oblong-elliptic, acutely acuminate, pinnately veined, dark green shiny above, paler beneath, 5-15 cm x 2-7 cm; male inflorescences usually 1-10 flowered cyme, fragrant, pale yellow, female inflorescences a 1-3 flowered cyme, but usually 1-flowered, pale yellow; fruit a fleshy, smooth, yellow, sub-globose, drupe, 3-6 cm long with a circumferential, longitudinal ridge; seed brown, ovoid 1.5-4.5cm long covered with a lacinate, red aril.
Nativa de Asia tropical, cultivada en los trópicos del resto del mundo.
Originaire d’;Asie tropicale, cultivée dans les tropiques du reste du monde.
Native to tropical Asia, cultivated in tropical regions around the world.

http://www.tramil.net/fototeca/plant239

Éditeur(s) : HAL CCSD Oldendorf/Luhe
Résumé : International audience
Non-calcifying photosynthetic anthozoans have emerged as a group that may thrive under high carbon dioxide partial pressure (pCO(2)) conditions via increased productivity. However, the physiological mechanisms underlying this potential success are unclear. Here we investigated the impact of high pCO(2) on the dissolved inorganic carbon (DIC) use in the temperate sea anemone Anemonia viridis. We assessed the impacts of long-term exposure to high pCO(2), i.e. sampling in situ natural CO2 vents (Vulcano, Italy), and short-term exposure, i.e. during a 3 wk controlled laboratory experiment. We focused on photo-physiological parameters (net photosynthesis rates, chlorophyll a content and Symbiodinium density) and on carbonic anhydrase (CA) activity, an enzyme involved in the energy-demanding process of DIC absorption. Long-term exposure to high pCO(2) had no impact on Symbiodinium density and chlorophyll a content. In contrst, short-term exposure to high pCO(2) induced a significant reduction in Symbiodinium density, which together with unchanged net photosynthesis resulted in the increase of Symbiodinium productivity per cell. Finally, in both in situ long-term and laboratory short-term exposure to high pCO(2), we observed a significant decrease in the CA activity of sea anemones, suggesting a change in DIC use (i.e. from an HCO3- to a CO2 user). This change could enable a shift in the energy budget that may increase the ability of non-calcifying photosynthetic anthozoans to cope with ocean acidification.
ISSN: 0171-8630

hal-01546163
https://hal.archives-ouvertes.fr/hal-01546163
DOI : 10.3354/meps11916

Éditeur(s) : Inter-research
Résumé : Mixed beds of Ophiocomina nigra and Ophiothrix fragilis (Echinodermata, Ophiuroidea) are usually predominated by O. fragilis and are reported to be stable over time. The Bay of Brest (Brittany, France) is a highly productive ecosystem where both species co-occur in the main central part. Using a geostatistical approach, we tested for changes in O. nigra and O. fragilis density and total biomass patterns between 1987 and 2011. Our results highlighted an increase in O. nigra population size and the induction of a spatial shift of the co-occurring O. fragilis. O. nigra increased similar to 5 times in density and covered almost all the study area, while its density-dependent biomass increased similar to 3 times (22 t km(-2), ash-free dry mass) between 1987 and 2011. Overall, the O. fragilis population decreased in density by similar to 30%, but its total biomass did not change over time. The current distribution pattern revealed a clear spatial exclusion of O. fragilis from the central part of the study area toward the southern part, overlapping beds of dead slipper limpet Crepidula fornicata, which were formerly considered to be the dominant suspension-feeder species in the bay. The success of O. nigra colonization is linked to its biological and functional traits, as well as deep changes in food supply over the studied period. Ecological consequences of such a large change in the benthic compartment of the bay are explored in the light of associated changes in environmental patterns.
Marine Ecology-progress Series (0171-8630) (Inter-research), 2012 , Vol. 460 , P. 79-90

Droits : 2012 Inter-Research
http://archimer.ifremer.fr/doc/00090/20136/17782.pdf
DOI:10.3354/meps09784
http://archimer.ifremer.fr/doc/00090/20136/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Local variation in the density of Anopheles mosquitoes and the risk of exposure to bites are essential to explain the spatial and temporal heterogeneities in the transmission of malaria. Vector distribution is driven by environmental factors. Based on variables derived from satellite imagery and meteorological observations, this study aimed to dynamically model and map the densities of Anopheles darlingi in the municipality of Saint-Georges de l’Oyapock (French Guiana). Longitudinal sampling sessions of An. darlingi densities were conducted between September 2012 and October 2014. Landscape and meteorological data were collected and processed to extract a panel of variables that were potentially related to An. darlingi ecology. Based on these data, a robust methodology was formed to estimate a statistical predictive model of the spatial-temporal variations in the densities of An. darlingi in Saint-Georges de l’Oyapock. The final cross-validated model integrated two landscape variables—dense forest surface and built surface—together with four meteorological variables related to rainfall, evapotranspiration, and the minimal and maximal temperatures. Extrapolation of the model allowed the generation of predictive weekly maps of An. darlingi densities at a resolution of 10-m. Our results supported the use of satellite imagery and meteorological data to predict malaria vector densities. Such fine-scale modeling approach might be a useful tool for health authorities to plan control strategies and social communication in a cost-effective, targeted, and timely manner.
ISSN: 1932-6203

hal-01383486
https://hal.archives-ouvertes.fr/hal-01383486
https://hal.archives-ouvertes.fr/hal-01383486/document
https://hal.archives-ouvertes.fr/hal-01383486/file/Adde_et_al_PlosONE_2016.pdf
DOI : 10.1371/journal.pone.0164685

Éditeur(s) : HAL CCSD Nordic Ecological Society
Résumé : Niche differentiation and ecological filtering are primary ecological processes that shape community assembly, but their relative importance remains poorly understood. Analyses of the distributions of functional traits can provide insight into the community structure generated by these processes. We predicted the trait distributions expected under the ecological processes of niche differentiation and environmental filtering, then tested these predictions with a dataset of 4672 trees located in nine 1-ha plots of tropical rain forest in French Guiana. Five traits related to leaf function (foliar N concentration, chlorophyll content, toughness, tissue density and specific leaf area), and three traits related to stem function (trunk sapwood density, branch sapwood density, and trunk bark thickness), as well as laminar surface area, were measured on every individual tree. There was far more evidence for environmental filtering than for niche differentiation in these forests. Furthermore, we contrasted results from species-mean and individual-level trait values. Analyses that took within-species trait variation into account were far more sensitive indicators of niche differentiation and ecological filtering. Species-mean analyses, by contrast, may underestimate the effects of ecological processes on community assembly. Environmental filtering appeared somewhat more intense on leaf traits than on stem traits, whereas niche differentiation affected neither strongly. By accounting for within-species trait variation, we were able to more properly consider the ecological interactions among individual trees and between individual trees and their environment. In so doing, our results suggest that the ecological processes of niche differentiation and environmental filtering may be more pervasive than previously believed.
ISSN: 0030-1299

hal-01032397
https://hal.archives-ouvertes.fr/hal-01032397
DOI : 10.1111/j.1600-0706.2010.19110.x

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Regeneration of artificially induced lesions was monitored in nubbins of the branching coral Acropora muricata at two reef-flat sites representing contrasting environments at Réunion Island (21u079S, 55u329E). Growth of these injured nubbins was examined in parallel, and compared to controls. Biochemical compositions of the holobiont and the zooxanthellae density were determined at the onset of the experiment, and the photosynthetic efficiency (F v /F m) of zooxanthellae was monitored during the experiment. Acropora muricata rapidly regenerated small lesions, but regeneration rates significantly differed between sites. At the sheltered site characterized by high temperatures, temperature variations, and irradiance levels, regeneration took 192 days on average. At the exposed site, characterized by steadier temperatures and lower irradiation, nubbins demonstrated fast lesion repair (81 days), slower growth, lower zooxanthellae density, chlorophyll a concentration and lipid content than at the former site. A trade-off between growth and regeneration rates was evident here. High growth rates seem to impair regeneration capacity. We show that environmental conditions conducive to high zooxanthellae densities in corals are related to fast skeletal growth but also to reduced lesion regeneration rates. We hypothesize that a lowered regenerative capacity may be related to limited availability of energetic and cellular resources, consequences of coral holobionts operating at high levels of photosynthesis and associated growth.
ISSN: 1932-6203

hal-01369712
http://hal.univ-reunion.fr/hal-01369712
http://hal.univ-reunion.fr/hal-01369712/document
http://hal.univ-reunion.fr/hal-01369712/file/journal.pone.0072618.PDF
DOI : 10.1371/journal.pone.0072618

Éditeur(s) : HAL CCSD Elsevier
Résumé : The dense hydrous magnesium silicate called the D phase is the most likely candidate to recycle hydrogen into the lower mantle in subduction zones. As seismology represents the preferred method to detect this mineral in subduction zones, the single crystal elastic tensor has been calculated using first principle methods. A triple cell (View the MathML source) was used to account for an ordered ideal composition of the D phase to lower mantle pressures. The elastic tensor of the mineral at ambient conditions is predicted to be C11 = 387.7, C33 = 287.7, C44 = 100.4, C12 = 108.0, C13 = 51.1, C14 = − 14.6 in GPa with bulk modulus at zero pressure Ko = 163 GPa and a statistical error of about 4.0 GPa for all constants. The pressure derivatives of the elastic constants have been determined to pressure of 80 GPa. Our tensor correctly predicts the published experimental measurements of linear compressibility along the a- and c-axes, the logarithmic pressure derivative of the c/a axial ratio and bulk modulus at zero pressure. It contradicts the experimentally measured elastic tensor reported by (Liu, L.-G., Okamoto, K., Yang, Y.-J., Chen, C.-C., Lin, C.-C., 2004. Elasticity of single-crystal phase D (a dense hydrous magnesium silicate) by Brillouin spectroscopy. Solid State Commun. 132, 517–520), which fails to reproduce the experimental compressibility data. Using the elastic constants and density predicted to 85 GPa, the seismic anisotropy of P- and S-waves has been calculated as a function of pressure. The single crystal has high P-wave velocities and shear wave splitting in the basal plane below 20 GPa. At high pressures, the maximum P-wave velocities have threefold symmetry normal to a-axes in the basal plane, whereas the maximum shear wave splitting is parallel to a-axes with twofold symmetry. The D phase has high Vp and Vs anisotropy at ambient pressure, 17.6% for Vp and 19.9% for Vs. The Vp anisotropy decreases with increasing pressure to about 30 GPa, while it remains constant at 8% from 30 to 85 GPa. The Vs anisotropy decreases to 17% at 20 GPa and then increases to 22% at 85 GPa. The isotropic velocity ratios of S to P (Rs/p), bulk sound to S (Rphi/s) and density to S (Rρ/s) are calculated as a function of pressure. The Rs/p shows very little variation with pressure with low value of 0.6, whereas both Rphi/s and Rρ/s increase with pressure to peak values of 2.8 and 2.0 respectively at about 60 GPa. The presence of the D phase in subducted horizontal ‘stagnant' plates in the circum Pacific could contribute to a number of seismic observations, such as the observed velocity heterogeneity at depths between 500 and 1000 km and the fast S-waves travelling horizontally with horizontal polarization in this depth range. Further the lower density of the D phase compared with anhydrous minerals could influence buoyancy of the hydrated ‘stagnant' slabs. The transformation of the D phase to perovskite plus ferripericlase during thermal annealing may be responsible for horizontal slab seismogenesis.
ISSN: 0012-821X

hal-00406379
https://hal.archives-ouvertes.fr/hal-00406379
DOI : 10.1016/j.epsl.2007.04.053

Résumé : Arbusto pequeño muy ramificado de hasta 30 cm de alto; ramas leñosas, rojas o purpúreas, puberulentas. Hojas fasciculadas, corto-pecioladas, elípticas a lineares, obtusas, agudas u obtusas en la base, enteras, conspicuamente glandular-punteadas. Verticilos con 3 a 6 flores, axilares; cáliz puberulento; corola lila, rosada o purpúrea. Nuececillas de 1 mm de longitud.
Petit arbuste très ramifié pouvant atteindre 30 cm de haut; branches ligneuses, rouges ou pourpres, pubérulentes. Feuilles fasciculées, à court pétiole, elliptiques à linéaires, obtuses, aiguës ou obtuses à la base, entières, pointe très nettement glandulaire. Verticilles de 3 à 6 fleurs, axillaires; calice pubérulent; corolle couleur lilas, rosée ou pourpre. Noisettes de 1 mm de longueur.
Densely branching, aromatic, shrub, 20-30 cm high.  Leaves lanceolate, entire, 0.5-1 cm x 0.2-0.5 cm, grayish-green, aromatic with glandular-dotted; flowers born in rounded or ovoid cluster, corolla 2-lipped, lilac, pink or purple; fruits tiny producing 4 nutlets.
Nativa de Europa, cultivada en otras partes del mundo.
Originaire d’;Europe, cultivée dans d’;autres parties du monde.
Native to Europe, cultivated in others parts of the world.

http://www.tramil.net/fototeca/plant350

Éditeur(s) : NRC
Résumé : We studied relationships between tropical tunas (albacore (Thunnus alalunga), bigeye (Thunnus obesus), and yellowfin (Thunnus albacares)) and their biotic and abiotic environments through simultaneous acoustic observations of tunas and their prey, experimental longline catch, and oceanographic data in French Polynesia. Vertical habitat limits were estimated based on temperature and dissolved oxygen at capture data. We then studied tuna-micronekton relationships to better understand how tuna occupy the pelagic space, At a regional scale, tunas were more abundant in areas rich in prey with favourable hydrological conditions. Inside such areas, at the scale of a longline set, however, the longline catches were maximal only when prey were not distributed in dense patches (except for yellowfin tuna). We interpreted this result by considering that areas with high prey abundance attract tunas, but at a small scale, if prey are patchy distributed, tunas are more inclined to feed on them rather than on longline baits. The effect of patches on yellowfin tuna catch per unit effort (CPUE) does not appear likely because this species also feeds on the mixed layer, where patch density was very low. Not only hydrological characteristics, but also prey density and prey patch characteristics, should be taken into account for interpreting longline CPUE data.
Thunnus obesus, et thon à nageoires jaunes, Thunnus albacares) à leurs environnements biotique et abiotique. Pour ce faire, nous avons réalisé simultanément, en Polynésie Française, des observations acoustiques des thons et de leurs proies, des pêches à l'aide d'une palangre instrumentée et des mesures hydrologiques. Des limites d'habitat vertical des thons calculées sur la base de données de température et d'oxygène dissous sont proposées. Nous étudions ensuite les relations thons-micronecton afin de mieux comprendre la stratégie d'occupation de l'espace des thons. A une échelle régionale, les thons sont plus abondants dans des zones riches en proies avec des conditions hydrologiques favorables. Cependant, à l'intérieur de telles zones, les captures sont maximales lorsque les proies ne sont pas distribuées sous forme de patchs (sauf pour le thon à nageoires jaunes). Nous interprétons ces résultats en considérant que les zones de fortes abondances en proies attirent les thons mais, qu'à une échelle fine, si les proies sont distribuées sous la forme de patchs denses, les thons s'en nourrissent préférentiellement, au détriment des appâts de la palangre. Ces patchs ne semblent pas influencer les prises par unité d'effort (PUE) des thons à nageoires jaunes, probablement parce que cette espèce se nourrit également dans la couche homogène où la densité en patchs est très faible. Les caractéristiques hydrologiques, mais également la densité en proies et leur type de distribution, devraient donc être pris en compte pour l'interprétation des données de PUE.
Canadian journal of fisheries and aquatic sciences (0706-652X) (NRC), 2002-06 , Vol. 59 , N. 6 , P. 1002-1013

Droits : 2002 NRC Canada
http://archimer.ifremer.fr/doc/2002/publication-733.pdf
DOI:10.1139/F02-073
http://archimer.ifremer.fr/doc/00000/733/

Éditeur(s) : Elsevier
Résumé : We examined the potential for producing the large numbers of sandfish (Holothuria scabra) needed for restocking programmes by co-culturing juveniles with the shrimp Litopenaeus stylirostris in earthen ponds. Our experiments in hapas within shrimp ponds were designed to detect any deleterious effects of sandfish on shrimp, and vice versa. These experiments showed that a high stocking density of juvenile sandfish had no significant effects on growth and survival of shrimp. However, survival and growth of sandfish reared with shrimp for 3 weeks were significantly lower than for sandfish reared alone. Increased stocking density of shrimp also had a significant negative effect on survival and/or growth of sandfish. A grow-out trial of juvenile sandfish in 0.2-ha earthen ponds stocked with 20 shrimp post-larvae m(-2), and densities of sandfish between 0.8 and 1.6 individuals m(-2), confirmed that co-culture is not viable. All sandfish reared in co-culture were dead or moribund after a month. However, sandfish stocked alone into 0.2-ha earthen ponds survived well and grew to mean weights of similar to 400 g within 12 months without addition of food. The grow-out trial demonstrated that there is potential for profitable pond farming of sandfish in monoculture. Further research is now needed to identify the optimal size of juveniles, stocking densities and pond management regimes. (C) 2007 Elsevier B.V. All rights reserved.
Aquaculture (0044-8486) (Elsevier), 2007-12 , Vol. 273 , N. 4 , P. 509-519

Droits : 2007 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2007/publication-3590.pdf
DOI:10.1016/j.aquaculture.2007.07.015
http://archimer.ifremer.fr/doc/00000/3590/

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
We calculated the seismic properties of 47 mantle xenoliths from 9 kimberlitic pipes in the Kaapvaal craton based on their modal composition, the crystal-preferred orientations (CPO) of olivine, ortho- and clinopyroxene, and garnet, the Fe content of olivine, and the pressures and temperatures at which the rocks were equilibrated. These data allow constraining the variation of seismic anisotropy and velocities within the cratonic mantle. The fastest P and S2 wave propagation directions and the polarization of fast split shear waves (S1) are always subparallel to olivine [100] axes of maximum concentration, which marks the lineation (fossil flow direction). Seismic anisotropy is higher for high olivine contents and stronger CPO. Maximum P wave azimuthal anisotropy (AVp) ranges between 2.5 and 10.2% and the maximum S wave polarization anisotropy (AVs), between 2.7 and 8%. Changes in olivine CPO symmetry result in minor variations in the seismic anisotropy patterns, mainly in the apparent isotropy directions for shear wave splitting. Seismic properties averaged over 20 km-thick depth sections are, therefore, very homogeneous. Based on these data, we predict the anisotropy that would be measured by SKS, Rayleigh (SV) and Love (SH) waves for five endmember orientations of the foliation and lineation. Comparison to seismic anisotropy data from the Kaapvaal shows that the coherent fast directions, but low delay times imaged by SKS studies, and the low azimuthal anisotropy with with the horizontally polarized S waves (SH) faster than the vertically polarized S wave (SV) measured using surface waves are best explained by homogeneously dipping (45°) foliations and lineations in the cratonic mantle lithosphere. Laterally or vertically varying foliation and lineation orientations with a dominantly NW-SE trend might also explain the low measured anisotropies, but this model should also result in backazimuthal variability of the SKS splitting data, not reported in the seismological data. The strong compositional heterogeneity of the Kaapvaal peridotite xenoliths results in up to 3% variation in density and in up to 2.3% variation of Vp, Vs, and Vp / Vs ratio. Fe depletion by melt extraction increases Vp and Vs, but decreases the Vp / Vs ratio and density. Orthopyroxene enrichment due to metasomatism decreases the density and Vp, strongly reducing the Vp / Vs ratio. Garnet enrichment, which was also attributed to metasomatism, increases the density, and in a lesser extent Vp and the Vp / Vs ratio. Comparison of density and seismic velocity profiles calculated using the xenoliths' compositions and equilibration conditions to seismological data in the Kaapvaal highlights that (i) the thickness of the craton is underestimated in some seismic studies and reaches at least 180 km, (ii) the deep sheared peridotites represent very local modifications caused and oversampled by kimberlites, and (iii) seismological models probably underestimate the compositional heterogeneity in the Kaapvaal mantle root, which occurs at a scale much smaller than the one that may be sampled seismologically.
ISSN: 1869-9510

hal-01053516
https://hal.archives-ouvertes.fr/hal-01053516
DOI : 10.5194/se-5-45-2014