Éditeur(s) : CIRAD : Centre de Coopération Internationale en Recherche Agronomique pour le Développement
Extrait de : 52e congrès annuel de la Société caribéenne des plantes alimentaires / 52nd annual meeting of the Caribbean food crops society (CFCS), du 10 au 16 juillet 2016. INRA, CFCS
Description : Breeding new interspecific banana hybrid varieties with pests and disease resistance characters is instrumental for the development of pesticide-free agroecological banana farming systems. Such breeding relies on the combined use of Musa acuminata and M. balbisiana parents. Unfortunately, infectious alleles of endogenous Banana streak virus (eBSV) sequences are present in the genome of M. balbisiana genitors. Upon activation by biotic and abiotic stresses, these infectious eBSVs lead to spontaneous infections by several species of Banana streak virus (BSV) in interspecific hybrids harbouring both M. acuminata and M. balbisiana genomes. In this work, we show that M. balbisiana diploid genitors available for breeding host at least one infectious eBSV. We also show how we segregated infectious and non-infectious eBSV alleles in seedy M. balbisiana diploids through self- pollination or chromosome doubling of haploid lines. We report on the successful breeding of M. balbisiana diploid genitors devoid of all infectious eBSV alleles following self-pollination and on the potential of breeding additional M. balbisiana diploid genitors free of infectious eBSVs by crossing parents displaying complementary eBSV patterns. This work paves the way to the safe use of M. balbisiana genitors for breeding banana interspecific hybrid varieties with no risk of activation of infectious eBSVs.
Siècle(s) traité(s) : 21
Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V16267
V16267

Résumé : (Funding) This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Sea Grant technical series, the Florida Geological Survey series, the Coastal Engineering Department series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
North America -- United States of America -- Florida
Florida
Florida

Droits : Copyright Walter S. Judd. Permission granted to University of Florida to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
http://ufdc.ufl.edu/UF00073894/00001

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In this study, we report new U-Pb zircon ages and amphibole and biotite 40Ar-39Ar cooling ages for igneous and metaigneous rocks from the eastern portion of the Borborema Province (NE Brazil). We combine these results with preliminary thermobarometric estimates and existing data to place constraints on the timing and duration of the Brasiliano-Pan-African Orogeny in northeastern Brazil and on the subsequent late- to post-orogenic history. The Alcantil orthogneiss contains a complex zircon population, but the youngest concordant analyses yielded an age of 632 ± 17 Ma (2σ). These grains have low Th/U ratios (<0.1), and the age of 632 Ma is therefore interpreted as dating the metamorphic event responsible for the acquisition of the gneissic fabric. In the Caruaru biotite amphibole orthogneiss, concordant analyses provided an age of 618 ± 4 Ma (2σ), which we relate to emplacement of the protolith of the Caruaru orthogneiss. Together with available U-Pb data from the literature, the 632-600 Ma age range is regarded as dating development of a regional flat-lying foliation coeval with high-grade metamorphism (upper amphibolite facies conditions). The 586 ± 3 Ma age (2σ) of the Panelas pluton is similar to those of other granitic plutons associated with a voluminous plutonism of high-K calc-alkaline to shoshonitic nature that occurred at 590-580 Ma. This plutonism slightly predated or was synchronous with development of large strike-slip shear zones. Amphibole grains yielded 40Ar-39Ar ages ranging from 584 ± 4 Ma to about 530 Ma, suggesting that regional temperatures remained near the closing temperature of this mineral (≈500 °C) for a long time. Most 40Ar-39Ar biotite ages range from 552 to 533 Ma, but two samples yielded plateau ages of 519 ± 5 Ma and 509 ± 5 Ma. The inferred rather slow cooling of the studied region possibly reflects low rates of unroofing, allowing persistence of a protracted thermal anomaly caused by the massive injection of magmas at the end of the Neoproterozoic.
ISSN: 0895-9811

hal-00745698
https://hal.archives-ouvertes.fr/hal-00745698
DOI : 10.1016/j.jsames.2012.06.003

Éditeur(s) : Université Bretagne Ouest
Résumé : This work deals with the fishing effects on the diversity dynamics of demersal fish communities, focusing on the biotic interactions. Multispecies indices are used in order to characterize the demersal fish community dynamics of the Bay of Biscay and of the Gulf of Lions. These are the diversity indices, the temporal variability of the total biomass and of the slope of the number size spectra and the slope of the species-area curves (spatial segregation). The yearly bottom trawl surveys EVHOE, CHALIST and MEDITS, carried out in these two areas since 1983 by IFREMER for the stocks assessment provide the data. The differences between areas are related to a fishing index (mean value of the annual landings of demersal fish per surface area). Other areas are included in the analysis when the index values are available from the published literature (North Sea, Scotian Shelf, Kenya, French Guyana). It is argued from the diversity indices analysis that the Gulf of Lions community is more diverse and less disturbed than the Bay of Biscay one. This result is not consistent with a fishing effect but with biogeography. The total biomass variability and the slope variability of size spectra are higher in the most harvested areas than in the least ones. On the contrary, the species-area slope is the lowest in the most harvested areas. Theoretically, biotic interactions decrease the total biomass variability and the spectra slope variability because of compensations and increase the species area slope because of competitive exclusion. It is concluded that harvesting alters biotic interactions and favour local coexistence by decreasing competitive exclusion. The species diversity maintenance depends on competitive exclusion. Hence, biodiversity is threatened not only by a direct fishing effect but also by a dynamics alteration.
Ce mémoire aborde le problème de l'impact de l'exploitation par la pêche sur la dynamique de diversité des peuplements de poissons démersaux. Les effets de la pêche sur le rôle des interactions biotiques entre espèces dans la dynamique des peuplements sont plus particulièrement analysés à l'aide de descripteurs multispécifiques. Les descripteurs utilisés sont les indices de diversité, la variabilité temporelle de la biomasse totale et de la pente multispécifique du spectre de poids et la pente des droites d'accumulation d'espèces mesurant la ségrégation spatiale. Les valeurs de ces indices sont calculées à partir des données de campagnes annuelles de chalutage de fond EVHOE, CHALIST et MEDITS, menées par l'IFREMER depuis 1983 pour l'évaluation des ressources halieutiques dans le golfe de Gascogne et dans le golfe du Lion. Les différences de caractéristiques de dynamique entre les deux peuplements révélées par ces descripteurs sont mises en relation avec un indice d'exploitation (valeur moyenne des débarquements annuels, divisée par la surface du plateau de la région concernée). D'autres régions ont été intégrées dans cette analyse lorsque les valeurs des indicateurs étaient disponibles dans la littérature (Mer du Nord, plateau de Nouvelle-Ecosse, Kenya et Guyane Française). Les indices de diversité utilisés permettent de mettre en évidence que le peuplement du golfe du Lion est plus diversifié et moins soumis à perturbations que celui du golfe de Gascogne. Ces caractéristiques semblent dues à l'histoire biogéographique de ces deux régions et non à un effet de la pêche. La variabilité de la biomasse totale et celle de la pente du spectre multispécifique augmentent depuis les régions les moins exploitées vers les plus exploitées. A l'inverse, la ségrégation spatiale diminue. En théorie, les interactions entre espèces diminuent la variabilité temporelle de la biomasse totale et de la pente du spectre multispécifique, à cause de compensations entre espèces, et augmentent la ségrégation spatiale par exclusion compétitive. L'interprétation donnée des résultats obtenus est ainsi une altération des interactions entre les espèces par l'exploitation. En prélevant de la biomasse, l'exploitation augmente la disponibilité des ressources pour les individus non pêchés. En conséquence, l'exclusion compétitive diminue et la coexistence locale des individus est facilitée. A long terme, la diversité est donc menacée, non seulement par raréfaction des espèces prélevées par l'exploitation mais aussi parce que les interactions sont altérées et que le maintien de la diversité en dépend pour partie.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2000/these-6670.pdf
http://archimer.ifremer.fr/doc/00000/6670/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The complex electrical impedance of a garnet-biotite-sillimanite residual enclave in the Neogene dacite of El Hoyazo (SE Spain) has been determined up to 978 °C at 200-300 MPa. This well studied material represents a direct sampling of the Alborán Domain thinned lower crust undergoing partial melting. The paragenesis is garnet + biotite + sillimanite + plagioclase + graphite ± cordierite coexisting with widespread (~ 10 wt.%) rhyolitic melt occurring as inclusions and interstitial glass and developed during regional anatexis at 850 ± 50 °C and 500-700 MPa. The samples were used in cyclic measurements consisting in heating-cooling ramps at progressively higher maximum temperature to observe the effect of reactions on conductivity. In the first cycle up to 850 °C at 2-3 kbar, re-melting of the interstitial glass is achieved with no additional reactions and logarithmic conductivity (S/m) is up to − 1.5. At T > 950 °C new melt with orthopyroxene + ilmenite is produced from biotite partial breakdown and the logarithmic conductivity (S/m) is up to − 0.7. Application of mixing models as Hashin-Shtrikman bounds or Archie's Law, shows that once interconnected, melt controls the electrical conductivity of the enclave. The electrical conductivity of the rock can be simulated with the electrical conductivity data obtained on the starting Matrix glass of the enclave and with the new melt. Our experimental results obtained on a graphitic metasedimentary material evidence show that graphite does not contribute to the conductivity enhancement and that the electrical anomaly observed below the Betics can be explained as effect of partial melting of a residual crust. Comparison with previous works on mafic granulites shows that similar conductivity values can be achieved both by melting of a residual felsic crust or by melting of mafic materials and suggests that pelitic rocks can be more common at deep levels than expected.
ISSN: 0040-1951

hal-00823063
https://hal.archives-ouvertes.fr/hal-00823063
DOI : 10.1016/j.tecto.2012.11.003

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Kazdag Massif exposes an extensional metamorphic dome in the Biga Peninsula of northwest Turkey, bounded on both flanks by detachments and/or shear zones. The northern flank is marked by the extensional Alakeci shear zone (ASZ), with poorly known P-T-t path. We therefore focus on metamorphic conditions and temporal history of the ASZ to determine its tectono-metamorphic evolution. ASZ mylonites were derived from both the footwall Kazdag Massif core metamorphic rocks and the hanging wall Cetmi melange lithologies. The mylonitic fabrics in the ASZ depict a top-to-the NNE shearing, parallel to the NNE-plunging stretching lineation and NNW-dipping mylonitic foliation. This geometry implies normal sense movement i.e. north-side down-dip extensional displacement along this flank of the Kazdag Massif. The northward transition from ductile to brittle-ductile shear regime through the ASZ shows that the non-coaxial deformation occurred at decreasing temperatures and degree of metamorphism. The paragenesis in equilibrium of the mylonitic gneisses and schists contains quartz + feldspar + muscovite + biotite + garnet staurolite, with late retrogressive chlorite after biotite and garnet. Calculated thermo-barometric conditions for ASZ rocks yielded pressures between 6.9 and 5.7 kbar and temperatures between 706 and 587 degrees C, which constrain the peak metamorphism. The mylonitic rocks supplied isochron Ar-39/Ar-40 mica ages between 26.97 and 24.19 Ma, which we interpret to date the cooling of the mylonites following the P-T decrease across the ASZ. The metamorphic data support the structural record and strengthen the extensional character of the ASZ. The transition from sillimanite-bearing footwall Kazdag Massif core gneisses in the deeper structural levels to chlorite schists; towards the shallow structural levels at the top of the ASZ, is consistent with an extensional exhumation of the metamorphic pile. These data allow us to determine the peak P-T conditions and the temporal evolution in the northern flank of the Kazdag Massif, where Late Oligocene extensional exhumation was assisted by NNE-directed ductile-brittle ASZ, which had operated from amphibolite to greenschist facies. The ASZ, together with similar time-constrained ductile-brittle activity of SW-directed detachment along the southern flank of the massif, collectively indicates a bivergent mode of extension in the western Kazdag Massif. The latter is likely influenced by magmatic activity spatially and temporally related to these extensional zones. At the regional scale, the bivergent tectono-metamorphic pattern of the Kazdag Massif is similar to those observed on other places of the north-central Aegean domain.
ISSN: 0024-4937

hal-00445246
https://hal.archives-ouvertes.fr/hal-00445246
DOI : 10.1016/j.lithos.2009.02.010

Éditeur(s) : INRA : Institut National de la Recherche Agronomique Université des Antilles. Service commun de la documentation
Extrait de : 52e congrès annuel de la Société caribéenne des plantes alimentaires / 52nd annual meeting of the Caribbean food crops society (CFCS), du 10 au 16 juillet 2016. INRA, CFCS
Description : In the Global South, improvement of agricultural outputs is eagerly awaited. While by 2050, its population will double areas devoted to agriculture will decrease exacerbating undernutrition of the poor. Unfortunately, the demand for fresh locally-produced meat products is not satisfied yet in the tropics. So, efficiency in animal productions is essential to allow coverage of protein nutritional needs of people, both in quality and quantity. In the Caribbean territories mixed farming systems are the most common farming systems (about 80%) and can constitute a solution to reach food sovereignty in such limited and isolated spaces. Lessons to be learned from these systems involve improving animal performance while respecting the natural balance with environment and maintaining the multi-functionality of plants and animals. Firstly, the natural (or selected) comfort zone of animal and plants must fit with the farm conditions, insuring thereby animal survival and welfare. Enhancement of adaptation to stresses (biotic, abiotic and socio- economic) in species or animal genotypes is a key element implying their equilibrium with the farm environment. This approach underpins for the farmer an integrated management of animal health, nutrition, genetics, reproduction, in close relationship with other compartments of the farming system. Secondly, animal adaptation may be completed by resilience ability within systems. Animals have to produce although facing stresses. Finally, the animal must be efficient that is to say must reconcile physiological functions of production, reproduction with adaptation functions. This optimization leads to decreased inputs and to overall efficiency of mixed farming systems at the end. The aim of the breeder is to choose the animal producing the best balance between output-reproduction-adaptation, at the individual or the flock scale combining genetic and physiological diversity. The underlying idea is to give to humans and animals their right place in the food chain taking into account the farmers? skills and wills. This idea is included in the agroecological approach and may give guidelines for food sovereignty worldwide.
Siècle(s) traité(s) : 21
Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V16318
V16318

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
AimBiological invasions are major contributors to global change and native biodiversity decline. However, they are overlooked in marine conservation plans. Here, we examine for the first time the extent to which marine conservation planning research has addressed (or ignored) biological invasions. Furthermore, we explore the change of spatial priorities in conservation plans when different approaches are used to incorporate the presence and impacts of invasive species.LocationGlobal analysis with a focus on the Mediterranean Sea region.MethodsWe conducted a systematic literature review consisting of three steps: (1) article selection using a search engine, (2) abstract screening and (3) review of pertinent articles, which were identified in the second step. The information extracted included the scale and geographical location of each case study as well as the approach followed regarding invasive species. We also applied the software Marxan to produce and compare conservation plans for the Mediterranean Sea that either protect, or avoid areas impacted by invasives, or ignore the issue. One case study focused on the protection of critical habitats, and the other on endemic fish species.ResultsWe found that of 119 papers on marine spatial plans in specific biogeographic regions, only three (2.5%) explicitly took into account invasive species. When comparing the different conservation plans for each case study, we found that the majority of selected sites for protection (ca. 80%) changed in the critical habitat case study, while this proportion was lower but substantial (27%) in the endemic fish species case study.Main conclusionsBiological invasions are being widely disregarded when planning for conservation in the marine environment across local to global scales. More explicit consideration of biological invasions can significantly alter spatial conservation priorities. Future conservation plans should explicitly account for biological invasions to optimize the selection of marine protected areas.
ISSN: 1366-9516

hal-01431351
https://hal-univ-perp.archives-ouvertes.fr/hal-01431351
DOI : 10.1111/ddi.12491

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
To quantify the relationships between anisotropy. S-wave splitting and tectonics, we determined the seismic properties of lower-crustal and upper-mantle rocks outcropping in the lvrea Zone (Northem Italy). We obtained P-and S-wave seismic velocities by laboratory direct velocity measurements and/or by calculations based on the modal compositions of the rocks, the lattice preferred orientations (LPOs), and the single crystal stiffness coefficients. Measured P-and S-wave velocities (6.0-7 .5 km s-1 and 3.6-4.2 km s-1) are typical of the lower crust. The P-wave anisotropy is in the range 0-l 0%. Shear-wave birefringence is in the range 0.0-0.6 km s-1 , with typical values between 0.0 and 0.2 km s-1 • In many cases, the birefringence is clearly related to fabric elements (foliation, lineation). Mafic rocks such as anorthosite or pyroxene-bearing gabbros exhibit low P-wave anisotropies (< 5%) and low shear-wave birefringences (less than 0.1 km s-1). In contrast, the seismic properties of felsic rocks such as biotite-bearing gneisses and mafic rocks such as amphibolites display high V P anisotropy (10%) and strong birefringence (0.3 km s-1). Biotite and amphibole preferred orientations clearly control seismic anisotropy and particularly shear-wave splitting. In these rocks, maximum splitting is observed in directions parallel to the foliation with the fast split shear wave polarized parallel to the foliation plane. To have an overview of the seismic properties of this lower-crustal section at a broader scale, we calculated from our data the anisotropie seismic properties of several hypothetical samples that are perhaps more representative of the regional anisotropy than each sample individually. For instance, the average lower-crustal sample displays an anisotropy of 5.5% for P waves and a birefringence around 0.14 km s I for S waves propagating parallel to the foliation. We observe little splitting for waves propagating at high angle to the foliation.
ISSN: 0031-9201

hal-01389712
http://hal.univ-reunion.fr/hal-01389712
http://hal.univ-reunion.fr/hal-01389712/document
http://hal.univ-reunion.fr/hal-01389712/file/Barruol_Kern-PEPI96_hal.pdf
DOI : 10.1016/0031-9201(95)03124-3

Éditeur(s) : Natl Shellfisheries Assoc
Résumé : The pearl industry in French Polynesia is based on exploitation of natural stocks of the black-lip pearl oyster (Pinctada margaritifera); it generates an annual turnover of 90 million euros. Improvements in pearl quality need genetic studies to improve the populations. This pearl oyster is a protandric species, where the sex-ratio normally is biased towards males. There is an increasing interest in gender control to find the mechanisms to augment female proportions for management purposes. This review summarizes information on exogenous and endogenous factors regulating gender in this and other bivalves and concludes that P. margaritifera is a protandric hermaphrodite, developing as a male during the first two years and without evidence of an effect from abiotic and biotic factors on gender during this phase. Later, pearl oysters progressively change to females, reaching a sex ratio close to 1:1 in specimens >8 years; at this stage, gender is apparently influenced by environmental parameters, but particularly by stress. Future research should seek to accurately determine the effect of temperature and food on sex ratios. Studies should be performed to characterize genes responsible for expression of gender. The use of hormones is a path that might be explored to influence the gender of pearl oysters.
Journal Of Shellfish Research (0730-8000) (Natl Shellfisheries Assoc), 2011-08 , Vol. 30 , N. 2 , P. 231-240

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00040/15100/12543.pdf
DOI:10.2983/035.030.0206
http://archimer.ifremer.fr/doc/00040/15100/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance at the species level is limited due to their small cell size and few morphological features visible under the light microscope. Here, we present unique data on haptophyte seasonal diversity and dynamics from two annual cycles, with the taxonomic resolution and sampling depth obtained with high-throughput sequencing. From outer Oslofjorden, S Norway, nano- and picoplanktonic samples were collected monthly for 2years, and the haptophytes targeted by amplification of RNA/cDNA with Haptophyta-specific 18S rDNA V4 primers. We obtained 156 operational taxonomic units (OTUs), from c. 400.000 454 pyrosequencing reads, after rigorous bioinformatic filtering and clustering at 99.5%. Most OTUs represented uncultured and/or not yet 18S rDNA-sequenced species. Haptophyte OTU richness and community composition exhibited high temporal variation and significant yearly periodicity. Richness was highest in September-October (autumn) and lowest in April-May (spring). Some taxa were detected all year, such as Chrysochromulina simplex, Emiliania huxleyi and Phaeocystis cordata, whereas most calcifying coccolithophores only appeared from summer to early winter. We also revealed the seasonal dynamics of OTUs representing putative novel classes (clades HAP-3-5) or orders (clades D, E, F). Season, light and temperature accounted for 29% of the variation in OTU composition. Residual variation may be related to biotic factors, such as competition and viral infection. This study provides new, in-depth knowledge on seasonal diversity and dynamics of haptophytes in North Atlantic coastal waters. See also the Perspective by Massana
ISSN: 0962-1083

hal-01545321
https://hal.archives-ouvertes.fr/hal-01545321
DOI : 10.1111/mec.13160

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The equilibrium phase relations of a mafic durbachite (53 wt.% SiO2) from the TA (TM) ebi pluton, representative of the Variscan ultrapotassic magmatism of the Bohemian Massif (338-335 Ma), have been determined as a function of temperature (900-1,100A degrees C), pressure (100-200 MPa), and H2O activity (1.1-6.1 wt.% H2O in the melt). Two oxygen fugacity ranges were investigated: close to the Ni-NiO (NNO) buffer and 2.6 log unit above NNO buffer (a dagger NNO + 2.6). At 1,100A degrees C, olivine is the liquidus phase and co-crystallized with phlogopite and augite at 1,000A degrees C for the whole range of investigated pressure and water content in the melt. At 900A degrees C, the mineral assemblage consists of augite and phlogopite, whereas olivine is not stable. The stability field of both alkali feldspar and plagioclase is restricted to low pressure (100 MPa) at nearly water-saturated conditions (< 3-4 wt.% H2O) and T < 900A degrees C. A comparison between experimental products and natural minerals indicates that mafic durbachites have a near-liquidus assemblage of olivine, augite, Ti-rich phlogopite, apatite and zircon, followed by alkali feldspar and plagioclase, similar to the mineral assemblage of minette magma. Natural amphibole, diopside and orthopyroxene were not reproduced experimentally and probably result from sub-solidus reactions, whereas biotite re-equilibrated at low temperature. The crystallization sequence olivine followed by phlogopite and augite reproduces the sequence inferred in many mica-lamprophyre rocks. The similar fractionation trends observed for durbachites and minettes indicate that mafic durbachites are probably the plutonic equivalents of minettes and that K- and Mg-rich magmas in the Bohemian Massif may have been generated from partial melting of a phlogopite-clinopyroxene-bearing metasomatized peridotite. Experimental melt compositions also suggest that felsic durbachites can be generated by simple fractionation of a more mafic parent and mixing with mantle-derived components at mid crustal pressures.
ISSN: 0010-7999

hal-00618418
https://hal.archives-ouvertes.fr/hal-00618418
DOI : 10.1007/s00410-009-0430-5

Éditeur(s) : HAL CCSD Elsevier
Résumé : A Ar-40/Ar-39 geochronological study was performed on amphibole and biotite from some representative units of distinct tectonic domains of the southeastern Guiana Shield, north of the Amazonian Craton, the Amapa Block and the Carecuru Domain. In the AmapA Block, an Archean continental block involved in the Transamazonian orogenesis (2.26-1.95 Ga), the investigated minerals, from rocks of the Archean high-grade basement assemblage, give only Paleoproterozoic ages, indicating their complete resetting during the Transamazonian orogenic event. Amphibole ages vary from 2087 +/- 3 to 2047 +/- 20 Ma, and biotite ages spread mainly between 2079 +/- 18 and 2033 +/- 13 Ma. In the Carecuru Domain, in which the geodynamic evolution is related to Paleoproterozoic magmatic arc setting during the Transamazonian event, calc-alkaline granitoids yield amphibole age of 2074 +/- 17 Ma, and biotite ages of 1928 +/- 19 Ma and 1833 +/- 13 Ma. These data reinforce the importance of the Transamazonian orogenic cycle in the investigated area, and indicate that the rocks were not significantly affected by post-Transamazonian events. When coupled with available U-Th-Pb monazite and Pb-Pb zircon geochronological records and petro-structural observations, the new Ar-40/Ar-39 data delineate contrasting cooling and exhumation histories for the tectonic domains. In the AmapA Block, the data suggest nearly vertical T-t paths that reflect fast cooling rates, which indicate tectonically controlled exhumation, related to collisional stages of the Transamazonian event, between 2.10 and 2.08 Ga. Conversely, in the Carecuru Domain, low cooling rates suggest that the arc-related granitoids underwent slow and monotonous cooling since their emplacement until reaching the biotite isotopic closure temperature.
ISSN: 0895-9811

hal-00420075
https://hal.archives-ouvertes.fr/hal-00420075
DOI : 10.1016/j.jsames.2008.08.010

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Despite the increasing dominance of turf algae in coral reefs, few studies have investigated their physiological and ecological responses to changes in abiotic factors. We tested the effects of depth and ultraviolet radiation on turf algae at different levels of successional stages using two experiments. Depth-related differences were found for all turf algal communities, characterized by a higher amount of the cyanobacteria taxon Dichothrix and the red filamentous genera Poly-/Herposiphonia in the shallow and the appearance of oscillating cyanobacteria in deeper waters. In the first experiment, cross-depth transplantation of 153 days old communities influenced percentage cover, biomass and taxa composition. Downward transplantation lowered overall biomass and abundance of the foraminifera Sorites, whereas the crustose green alga Pringsheimiella and filamentous cyanobacteria colonized the communities. A nearly reverse pattern was observed in upward transplanted communities. Overall we distinguished between sensitive taxa, like Oscillatoria, and taxa able to acclimate to alterations in their environment, like Pringsheimiella, Poly/Herposiphonia and Dichothrix. In the second experiment, algae grown for 285 days at 5 m were exposed together with a set of sterile settlement tiles to three UVR regimes at 2 m for 22 days. UVR had no effect on turf algal communities regardless of successional stage. This study highlights the presence of high light and UV tolerant species. The high UV tolerance of turf communities may confer a competitive advantage over other more sensitive coral reef biota, such as corals. This study demonstrates that turf algae are dynamic communities exhibiting species-specific resistance to environmental changes.
ISSN: 0022-0981

hal-01333486
https://hal-univ-perp.archives-ouvertes.fr/hal-01333486
DOI : 10.1016/j.jembe.2014.07.017

Éditeur(s) : HAL CCSD Springer
Résumé : International audience
In the Dent Blanche Tectonic System, the Mont Morion biotite-bearing granite is a km-scale intrusion preserved in a low-strain volume. Zircon saturation thermometry suggests that it crystallised from a melt that reached about 800 °C. U–Pb zircon and allanite geochronology indicates crystallization of the magma in the Permian (290 ± 3 Ma; 280 ± 8 Ma, respectively). Migmatitic biotite-gneiss and amphibolite are found as xenoliths within the Mont Morion granite and constitute its country-rocks. In two samples of migmatitic biotite-gneiss zircon has metamorphic overgrowths that yield U–Pb ages of 285 ± 3 Ma and 281 ± 4 Ma, and are thus contemporaneous with the intrusion of the granite. The Mont Morion granite with its country-rocks of migmatitic biotite-bearing gneiss and amphibolite was thus emplaced at middle crustal levels while amphibolite facies metamorphism affected its country rocks. The magmatic and metamorphic record in the Mont Morion area reflects the high-temperature regime and lithospheric thinning of the Adriatic continental margin during Permian.
ISSN: 1661-8726

insu-01622179
https://hal-insu.archives-ouvertes.fr/insu-01622179
DOI : 10.1007/s00015-017-0284-1

Éditeur(s) : HAL CCSD E Schweizerbart Science Publishers
Résumé : Mafic microgranular enclaves produced by co-mingling between minette and syenite magmas are found in the Piquiri Syenite, southern Brazil. These enclaves were crystallized under upper mantle conditions. K-clinopyroxene and pyrope are among the early-crystallized phases, suggesting an initial pressure around 5GPa. The mineralogy of minettes comprises phenocrysts of magnesium biotite and diopside, occasionally apatite, in a groundmass formed by these minerals plus alkali feldspar. Two types of apatites are observed: (i) euhedral grains, as inclusions or groundmass constituents, and (ii) aciculate crystals formed during undercooling of mafic magma. Substitutional schemes suggested for these apatites are Si ⇆ P in the tetrahedral site, and Sr and LREE replacing Ca. La, Ce, Nd, and Sr concentrations reveal that these elements are extremely enriched in apatite. Partition coefficients between early-crystallized apatites and estimated melt compositions are DLa (11.8 - 30.6), DCe (16.1-33), DNd (12-31) and DSr (5.1-8.2). Apatite concentrates the LREE up to 200 times compared to clinopyroxene, even higher values were determined for ap/mica partitioning. The ap/cpx and ap/mica partition coefficients for undercooled minerals are close to the values determined for the near-liquidus phases, which indicates constant behavior of LREE and Sr between apatite-clinopyroxene-mica parageneses and minette liquids. Furthermore, these partitioning data preclude any chemical diffusion of these elements between minette and syenite magmas during co-mingling.
ISSN: 0935-1221

hal-00407602
https://hal.archives-ouvertes.fr/hal-00407602
DOI : 10.1127/0935-1221/2007/0019-0039

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : In this work we combined apatite fission track and biotite/K-feldspar 40Ar/39Ar ages with tectonic data in the west central part of the Axial Zone of the Pyrenees. We discuss the exhumation ages and rates of the Néouvielle, Bordère-Louron, and Bielsa Variscan granites and their relationships with the timing and sequence of south vergent basement thrusting within the Pyrenean orogenic prism. The 40Ar/39Ar ages on K-feldspars from the Néouvielle massif (sample NV7) seem to indicate tectonic movements on the Eaux-Chaudes thrust during the early middle Eocene. Fission track results suggest that the exhumation of the Néouvielle massif occurred around 35 Ma and exhumation of the Bordère-Louron massif around 32 Ma in relation to thrusting on the Gavarnie thrust. The Bielsa massif was exhumed from around 19 Ma by out-of-sequence movements on the Bielsa thrust. We thus show that whereas most of the Pyrenean basement thrust faults (here the Eaux-Chaudes, Gavarnie, and Guarga thrusts) were active in sequence toward the southern foreland from the early Eocene to the earliest Miocene, some of them (here the Bielsa thrust) were activated out of sequence in the hinterland, later than the generally accepted Aquitanian age for the end of the Pyrenean compression. Finally, the apatite fission track modeling indicate a last cooling episode starting around 5 Ma which is most certainly related to the Pliocene reexcavation of the southern and northern flanks of the Pyrenees
ISSN: 0278-7407

hal-00406582
https://hal.archives-ouvertes.fr/hal-00406582
DOI : 10.1029/2006TC002080

Éditeur(s) : Soc Francaise D Ichtyologie
Résumé : This work deals with the fishing effects on the diversity dynamics of demersal fish communities, focusing on the biotic interactions. Multispecies indices were used in order to characterise the demersal fish community dynamics of the Bay of Biscay and of the Gulf of Lions. These are the diversity indices, the temporal variability of the total biomass and of the slope of the number size spectra and the slope of the species-area curves (spatial segregation). The data were provided by yearly bottom trawl surveys EVHOE, CHALIST and MEDITS carried out in these two areas since 1983 by IFREMER for stock assessment. The differences between areas are related to a fishing index (mean value of the annual landings of demersal fish per surface area). Other areas are included in the analysis when the index values are available from the published literature (North Sea, Scotian Shelf, Kenya, French Guyana). From the diversity indices analysis it is argued that the Gulf of Lions community is more diverse and less disturbed than the Bay of Biscay one. This result is not consistent with a fishing effect. It is interpreted as a biogeography pattern. The total biomass variability and the slope variability of size spectra are higher in the most harvested areas than in the least ones. On the contrary, the species-area slope is the lowest in the most harvested areas. Theoretically, biotic interactions decrease the total biomass variability and the spectra slope variability because of compensations, and increase the species area slope because of competitive exclusion. It is concluded that harvesting alters biotic interactions and favours local coexistence by decreasing competitive exclusion. The species diversity maintenance depends on competitive exclusion. Hence, biodiversity is threatened not only by a direct fishing effect but also by a dynamics alteration.
Ce mémoire aborde le problème de l'impact de l'exploitation par la pêche sur la dynamique de diversité des peuplements de poissons démersaux. Les effets de la pêche sur le rôle des interactions biotiques entre espèces dans la dynamique des peuplements sont plus particulièrement analysés à l'aide de descripteurs multispécifiques. Les descripteurs utilisés sont les indices de diversité, la variabilité temporelle de la biomasse totale et de la pente multispécifique du spectre de poids et la pente des droites d'accumulation d'espèces mesurant la ségrégation spatiale. Les valeurs de ces indices sont calculées à partir des données de campagnes annuelles de chalutage de fond EVHOE, CHALIST et MEDITS, menées par l'IFREMER depuis 1983 pour évaluer les ressources halieutiques dans le golfe de Gascogne et dans le golfe du Lion. Les différences de caractéristiques de dynamique entre les deux peuplements révélées par ces descripteurs sont mises en relation avec un indice d'exploitation (valeur moyenne des débarquements annuels, divisée par la surface du plateau de la région concernée). D'autres régions ont été intégrées dans cette analyse lorsque les valeurs des indicateurs étaient disponibles dans la littérature (Mer du Nord, plateau de Nouvelle-Ecosse, Kenya et Guyane Française). Les indices de diversité utilisés permettent de mettre en évidence que le peuplement du golfe du Lion est plus diversifié et moins soumis à perturbations que celui du golfe de Gascogne. Ces caractéristiques semblent dues à l'histoire biogéographique de ces deux régions et non à un effet de la pêche. La variabilité de la biomasse totale et celle de la pente du spectre multispécifique augmentent depuis les régions les moins exploitées vers les plus exploitées. A l'inverse, la ségrégation spatiale diminue. En théorie, les interactions entre espèces diminuent la variabilité temporelle de la biomasse totale et de la pente du spectre multispécifique, à cause de compensations entre espèces, et augmentent la ségrégation spatiale par exclusion compétitive. L'interprétation donnée des résultats obtenus est ainsi une altération des interactions entre les espèces par l'exploitation. En prélevant de la biomasse, l'exploitation augmente la disponibilité des ressources pour les individus non pêchés. En conséquence, l'exclusion compétitive diminue et la coexistence locale des individus est facilitée. A long terme, la diversité est donc menacée, non seulement par raréfaction des espèces prélevées par l'exploitation mais aussi parce que les interactions sont altérées et que le maintien de la diversité en dépend pour partie.
Cybium (0399-0974) (Soc Francaise D Ichtyologie), 2001 , Vol. 25 , N. 3 , P. 293-294

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00000/10248/7688.pdf
http://archimer.ifremer.fr/doc/00000/10248/

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
This paper aims to decipher the thermal evolution of the Montagne Noire Axial Zone (MNAZ,southern French Massif Central) gneiss core and its metasedimentary cover through determination ofP–T paths and temperature gradients. Migmatitic gneiss from the core of the dome record a clock-wise evolution culminating at 725 25 °C and 0.8 0.1 GPa with partial melting, followed by adecompression path with only minor cooling to 690 25° C and 0.4 0.1 GPa. Field structuralanalyses as well as detailed petrological observations interpreted in a petrogenetic grid indicate thatthe cover sequence experienced LP-HT metamorphism at <0.4 GPa. Apparent thermal gradientswithin the cover were determined with garnet–biotite thermometry and Raman Spectroscopy on Car-bonaceous Matter. High-temperature apparent gradients (e.g. 530 °C km1 along one transect) areexplained by late brittle–ductile extensional shearing evidenced by phyllonites that post-date peakmetamorphism. In areas where normal faults are less abundant and closely spaced, gradients of 20to 50 °C km1 are calculated. These gradients can be accounted for by a combination of domeemplacement and ductile shearing (collapse of isotherms), without additional heat input. Finally, thethermal evolution of the MNAZ is typical for many gneiss domes worldwide as well as with otherLP-HT terranes in the Variscides.
ISSN: 0263-4929

Droits : http://creativecommons.org/licenses/by-nc-nd/
insu-01290388
https://hal-insu.archives-ouvertes.fr/insu-01290388
https://hal-insu.archives-ouvertes.fr/insu-01290388/document
https://hal-insu.archives-ouvertes.fr/insu-01290388/file/jmg12188.pdf
DOI : 10.1111/jmg.12188

Éditeur(s) : Elsevier
Résumé : The ecological quality status (EcoQ) of intertidal mudflats constrained by Pacific oyster farming was assessed by single (H', AMBI, BENTIX and BOPA) and multimetric (M-AMBI and average score) index approaches in the Pertuis Charentais (SW France). Fifteen sampling stations were monitored seasonally for sedimentological features and macrozoobenthos in 2004. Sediments affected by oyster biodeposits showed organic matter enrichment, and sediments from off-bottom culture sites had higher organic matter contents and lower redox potentials than sediments from on-bottom culture sites. Biotic indices consistently registered responses of macrozoobenthos to organic enrichment but there was only partial agreement between single index-derived EcoQs. The average score was better than M-AMBI and single indices for determining EcoQs. Accordingly, oyster farming alters intertidal macrozoobenthic assemblages moderately, and off-bottom cultures cause more disturbance than on-bottom cultures. Hydrodynamics and seasons may interact with culture practices in smothering/strengthening biodeposition-mediated effects through dispersal/accumulation of biodeposits.
Marine Pollution Bulletin (0025-326X) (Elsevier), 2008-11 , Vol. 56 , N. 11 , P. 1898-1912

Droits : 2008 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/2008/publication-4650.pdf
DOI:10.1016/j.marpolbul.2008.07.010
http://archimer.ifremer.fr/doc/00000/4650/