Long-term disruption of growth, reproduction, and behavior after embryonic exposure of zebrafish to PAH-spiked sediment
A natural sediment spiked with three individual polycyclic aromatic hydrocarbons (PAHs; pyrene, phenanthrene and benzo[a]pyrene) was used to expose zebrafish embryos and larvae during 4 days. The total PAH concentration was 4.4 μg g−1 which is in the range found in sediment from contaminated areas. Quantification of metabolites in the larvae after exposure confirmed the actual contamination of the larvae and indicated an active metabolism specially for pyrene and benzo[a]pyrene. After a transfer in a clean medium, the larvae were reared to adulthood and valuated for survival, growth, reproduction, and behavior. Measured endpoints revealed a late disruption of growth (appearing at 5 months) and a trend toward a lower reproductive ability. Adults of embryos exposed to sediment spiked with PAHs displayed lethargic and/or anxiety-like behaviors. This latter behavior was also identified in offspring at larval stage. All together, these effects could have detrimental consequences on fish performances and contribution to recruitment.
(Environmental Science and Pollution Research. vol. 21, n° 0944-1344, pp. 13877-13887, 01/12/2014)
BE, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LRHLR, HGS, IFREMER, LPGP, INRA, Biosit : Biologie - Santé - Innovation Technologique
High frequency environmental changes and deposition processes in a 2 kyr-long sedimentological record from the Cap-Breton canyon (Bay of Biscay)
The core MD03-2693 (43°39.258′N; 01°39.805′W; 431 m water depth) was collected on an abandoned meander of the Capbreton Canyon (SE Bay of Biscay), filled over the last millennia by very high sedimentation rates (mean sedimentation rate of 1.2 cm/yr) linked to its specific environmental location and fine-grained clayed sediment decantation from the proximal canyon axis. This archive thus permits to undertake the study of late Holocene regional climatic patterns at a decadal temporal resolution. In the present work, we use data derived from planktonic foraminifera assemblages coupled to a multiproxy approach that associates grain-size measurements, x-ray fluorescence (XRF) elemental analysis and stable oxygen isotope on Globigerina bulloides shells to infer Sea Surface Temperature (SST) and Sea Surface Salinity (SSS) changes over the last two millennia. Signals reconstructed in the Bay of Biscay show significant oscillations that are consistent with well-known temperature anomalies such as the ‘Little Ice Age’ (LIA) and the ‘Medieval Warm Period’ (MWP). It additionally displays strong similarities with other areas in the western temperate and northern North Atlantic Ocean, suggesting a narrow coupling between its main gyre surface systems. Abrupt decrease of SSS together with significant change in terrigenous inputs suggests a change in precipitation regime at the onset of the LIA (around ad 1400). Moreover, superimposed to the relative long-term change in environmental parameter, the core MD03-2693 records rapid and discrete pulses of sand grain–sized material that are correlated with the local history of migration of the mouth of the Adour River.
(The Holocene. vol. 25, n° 0959-6836, pp. 348-365, 27/11/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Wandering Albatrosses Document Latitudinal Variations in the Transfer of Persistent Organic Pollutants and Mercury to Southern Ocean Predators
Top marine predators are effective tools to monitor bioaccumulative contaminants in remote oceanic environments. Here, we used the wide-ranging wandering albatross Diomedea exulans to investigate potential geographical variations of contaminant transfer to predators in the Southern Ocean. Blood concentrations of 19 persistent organic pollutants and 14 trace elements were measured in a large number of individuals (N = 180) of known age, sex and breeding status from the subantarctic Crozet Islands. Wandering albatrosses were exposed to a wide range of contaminants, with notably high blood mercury concentrations. Contaminant burden was markedly influenced by latitudinal foraging habitats (inferred from blood δ13C values), with individuals feeding in warmer subtropical waters having lower concentrations of pesticides, but higher concentrations of mercury, than those feeding in colder subantarctic waters. Sexual differences in contaminant burden seemed to be driven by gender specialization in feeding habitats, rather than physiological characteristics, with females foraging further north than males. Other individual traits, such as adult age and reproductive status, had little effect on blood contaminant concentrations. Our study provides further evidence of the critical role of global distillation on organic contaminant exposure to Southern Ocean avian predators. In addition, we document an unexpected high transfer of mercury to predators in subtropical waters, which merits further investigation.
(Environmental Science and Technology. vol. 48, n° 0013-936X, pp. 14746-14755, 21/11/2014)
CEBC, INRA, ULR, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPTC, UB, CNRS
Variabilité climatique centre/est Pacifique au cours du dernier millénaire reconstruite à partir d’analyses géochimiques sur des coraux massifs
L’océan Pacifique est le siège de variabilités climatiques interannuel et multi-décennale, El Niño Southern Oscillation (ENSO) et la Pacific Decadal Oscillation (PDO), dont les répercussions (via des téléconnections) peuvent être mondiales. Des impacts importants sur les populations, les activités socio-économiques et sur l’environnement ont été attribuées à ENSO. Il est alors primordial d’améliorer notre compréhension de la dynamique Pacifique et notamment du phénomène ENSO ainsique son évolution sous l’effet du changement climatique.Les mesures géochimiques (Sr/Ca et 818O) réalisées sur les coraux constituent des enregistrements paléoclimatiques de choix pour l’étude de l’évolution d’ENSO et sont essentielles pour mettre en perspective la dynamique actuelle du climat par rapport à sa dynamique passée. Après avoir évaluer la robustesse du paléothermomètre géochimique corallien (Sr/Ca), cette thèse a permis la reconstruction de température de surface océanique (SST) à partir de coraux de l’atoll de Clipperton (Pacifique tropical Est) et de l’archipel des Marquises (Pacifique tropical centre) couvrantplusieurs parties du dernier millénaire. Nos résultats suggèrent que la structure spatiale d’ENSO étaitplutôt stable au cours des deux derniers siècles, montrant majoritairement une structure de type ENSOcanonique (Est Pacifique) par opposition à l’ENSO Modoki (centre Pacifique). Bien qu’encore débattue, cette structure spatiale pourrait avoir évoluée très récemment, en liaison avec le changement climatique global (et cela pourrait continuer dans le futur). A l’échelle décennale, nos deux zones d’étude (centre et Est Pacifique) sont influencées par la PDO.Les résultats de cette thèse tendent également à suggérer que l’activité d’ENSO actuelle (sous l’effet du forçage anthropique) n’est pas atypique à l’échelle du dernier millénaire. En effet, son intensité et sa fréquence étaient plus fortes au début du petit âge glaciaire (LIA, 16ème siècle). La comparaison deces résultats avec un ensemble de simulations climatiques (PMIP3) montre que la variabilité ENSO estbien reproduite par ces modèles climatiques mais qu’ils échouent à reproduire correctement l’état moyen des températures du Pacifique.
(21/11/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Study of the aquatic dissolved organic matter from the Seine River catchment (France) by optical spectroscopy combined to asymmetrical flow field-flow fractionation
The main goal of this thesis was to investigate the characteristics of dissolvedorganic matter (DOM) within the Seine River catchment in the Northern part of France. ThisPhD thesis was performed within the framework of the PIREN-Seine research program. Theapplication of UV/visible absorbance and EEM fluorescence spectroscopy combined toPARAFAC and PCA analyses allowed us to identify different sources of DOM andhighlighted spatial and temporal variations of DOM properties. The Seine River wascharacterized by the strongest biological activity. DOM from the Oise basin seemed to havemore "humic" characteristics, while the Marne basin was characterized by a third specifictype of DOM. For samples collected during low-water periods, the distributions of the 7components determined by PARAFAC treatment varied between the studied sub-basins,highlighting different organic materials in each zone. A homogeneous distribution of thecomponents was obtained for the samples collected in period of flood.Then, a semi-quantitative asymmetrical flow field-flow fractionation (AF4) methodology wasdeveloped to fractionate DOM. The following optimized parameters were determined: across-flow rate of 2 ml min-1 during the focus step with a focusing time of 2 min and anexponential gradient of cross-flow from 3.5 to 0.2 ml min-1 during the elution step. Thefluorescence properties of various size-based fractions of DOM were evaluated by applyingthe optimized AF4 methodology to fractionate 13 samples, selected from the three sub-basins.The fluorescence properties of these fractions were analysed, allowing us to discriminatebetween the terrestrial or autochthonous origin of DOM.
(06/11/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Multimodel analysis on the response of the AMOC under an increase of radiative forcing and its symmetrical reversal
The response of the Atlantic meridional overturning circulation (AMOC) to an increase of radiative forcing (ramp-up) and a subsequent reversal of radiative forcing (ramp-down) is analyzed for four different global climate models. Due to changes in ocean temperature and hydrological cycle, all models show a weakening of the AMOC during the ramp-up phase. Once the external forcing is reversed, the results become model dependent. For IPSL-CM5A-LR, the AMOC continues its weakening trend for most of the ramp-down experiment. For HadGEM2-ES, the AMOC trend reverses once the external forcing also reverses, without recovering its initial value. For EC-EARTH and MPI-ESM-LR the recovery is anomalously strong yielding an AMOC overshoot. A robust linear dependency can be established between AMOC and density difference between North Atlantic (NA) deep water formation region and South Atlantic (SA). In particular, AMOC evolution is primarily controlled by a meridional salinity contrast between these regions. During the warming scenario, the subtropical Atlantic becomes saltier while the NA experiences a net freshening which favours an AMOC weakening. The different behaviour in the models during the ramp-down is dependent on the response of the ocean at the boundaries of NA and SA. The way in which the positive salinity anomaly stored in the subtropical Atlantic during the ramp-up is subsequently released elsewhere, characterizes the recovery. An out-of-phase response of the salinity transport at 48° N and 34°S boundaries is able to control the meridional density contrast between NA and SA during the transient experiments. Such a non-synchronized response is mainly controlled by changes in gyre salinity transport rather than by changes in overturning transport, thus suggesting a small role of the salt advection feedback in the evolution of the AMOC.
(Climate Dynamics. vol. 45, n° 0930-7575, pp. 1429-1450, 05/11/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Carbonate slopes and gravity deposits
In this special volume a series of papers are presented that concentrate on sedimentation patterns observed on the slopes and within the basins surrounding shallow-water carbonate depositional systems. Four papers discuss depositional patterns on the slope to basin transect of the Cainozoic sedimentary system of the Bahamas; four other papers examine gravity deposits of Jurassic and Cretaceous carbonate depositional systems.
(Sedimentary Geology, n° 0037-0738, 01/11/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
SOPHIE velocimetry of Kepler transit candidates XII. KOI-1257 b: a highly eccentric three-month period transiting exoplanet
In this paper we report a new transiting warm giant planet: KOI-1257 b. It was first detected in photometry as a planet-candidate by the Kepler space telescope and then validated thanks to a radial velocity :follow-up with the SOPHIE spectrograph. It orbits its host star with a period of 86,647661 d +/- 3 s and a high eccentricity of 0.772 +/- 0.045. The planet transits the main star of a metal-rich, relatively old binary system With stars of mass of 0.99 +/- 0.05 M-circle dot and 0.70 +/- 0.07 M-circle dot for the primary and secondary, respectively. This binary system is constrained thanks to a self-consistent modelling of the Kepler transit light curve; the SOPHIE radial velocities; line bisector and full-width half maximum (FWHM) variations, and the spectral energy distribution. However, future observations are needed to confirm it. The PASTIS fully-Bayesian software was used to validate the nature of the planet and to determine which star of the binary system is the transit host. By accounting for the dilution from the binary both in photometry and in radial velocity, we find that the planet has a mass of 1.45 +/- 0.35 M-4, and a radius of 0.94(4) +/- 0.12 R-4 and thus a bulk density of 2.1 +/- 1.2 g cm(-3). The planet has an equilibrium temperature of 511 +/- 50K, making it one of the few known members of the warm-Jupiter population. The HARPS-N spectrograph was also used to observe a transit of KOI-1257 b, simultaneously with a joint amateur and professional photometric follow up, with the aim of constraining the orbital obliquity of the planet. However, the Rossiter-McLaughlin effect was not clearly detected, resulting in poor constraints on the orbital obliquity of the planet.
(Astronomy & Astrophysics - A&A. vol. 571, n° 0004-6361, 01/11/2014)
CAUP, IAP, UPMC, INSU - CNRS, CNRS, LAM, AMU, INSU - CNRS, CNES, CNRS, IMCCE, UPMC, INSU - CNRS, CNRS, PSL, CNRS, CBMSO, CSIC, UAM, UNIGE, OHP, OSU PYTHEAS, IRD, AMU, IRSTEA, CNRS, LMNO, UNICAEN, NU, CNRS, LAGRANGE, UNS, INSU - CNRS, UniCA, CNRS, UniCA, ESO, AUDE, DFA/FCUP, FCUP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CALA, EDF R&D STEP, EDF R&D, EDF [E.D.F.], UniCA
Utilisation du comportement natatoire de Daphnia magna comme indicateur sensible et précoce de toxicité pour l'évaluation de la qualité de l'eau
Les paramètres comportementaux sont de plus en plus considérés comme étant des indicateurs sensibles et précoces de toxicité chez les organismes aquatiques. Cependant, l’utilisation du comportement natatoire comme critère de toxicité pour l’analyse de risque environnemental ou pour le contrôle de la qualité de l’eau reste pour l’heure encore limitée. En effet, il est actuellement difficile de quantifier la sensibilité des paramètres comportementaux et d’établir un lien entre les seuils d’effets comportementaux et les effets aigus et subaigus classiquement mesurés dans les tests en écotoxicologie. Dans le but d’améliorer notre compréhension des effets comportementaux des polluants sur Daphnia magna, nous avons développé un nouveau système de mesure du comportement multi-cuves baptisé «Multi-DaphTrack ». Douze substances toxiques, couvrant une large gamme de modes d’action différents ont été testées dans ce système. Un test standard d’immobilisation ainsi que des analyses de comportement dans le toximètre DaphToxI®, ont également été effectués pour chaque substance afin de comparer les seuilsd’effets comportementaux avec les paramètres classiques d’immobilisation. Les résultats des expositions aux différentes substances ont démontré que notre nouveau système d’exposition multi-cuves permet de détecter des effets comportementaux (i.e.,augmentation de la vitesse de nage) significatifs et précoces pour l’ensemble des substances testées et ce, à des concentrations proches de la CE10(48 h) du test aigu d’immobilisation dès la première heure d’exposition. Des profils comportementaux différents ont été observés selon les substances testées (i.e., intensité, temps de latence et durée de l’effet) mais ceux-ci ne sont pas spécifiques d’un mode d’action particulier. Les résultats obtenus avec le toximètre DaphToxI®ont révélé des profils d’effet similaires (i.e.,augmentation de la vitesse de nage) bien que ce système soit globalement moins sensible par rapport au système «Multi-DaphTrack». Pour conclure, notre nouveau système d’exposition multi-cuves «Multi-DaphTrack» est un outil plus sensible et précoce que letest standard d’immobilisation pour l’évaluation de la toxicité de substances chimiques. L’utilisation du système «Multi-DaphTrack» pourrait donc être envisagée, après quelques améliorations et validation supplémentaires, pour l’évaluation de la qualité des masses d’eauet des effluents.
(30/10/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EDF R&D LNHE, EDF R&D, EDF [E.D.F.]
Large-Scale Carbonate Submarine Mass-Wasting along the Northwestern Slope of the Great Bahama Bank (Bahamas): Morphology, Architecture, and Mechanisms
Along the northwestern margin of the Great Bahama Bank (Bahamas), high-resolution multibeam bathymetry maps have revealed large escarpments, 80-100 m in height, and gigantic carbonate Mass Transport Complexes (MTCs), characterized by megablocks, several hundred to several thousand meters in size.The present-day configuration of this mass-wasting deposit is the result of the specific basinal sedimentation of the GBB during the Neogene. Marginal sedimentation was produced by: (i) massive gravity-flow slope apron carbonates, feeding from the eastern prograding platform, including oversized MTCs; and (ii) thick, elongated, and muddier drift contourite flowing from south to north along the toe of slope. Four distinct MTCs (MTC-1 to -4) resulted from repeated slope failures in the Late Pliocene and the Pleistocene. These MTCs all glided along a common privileged décollement surface, dated Late Messinian – Early Pliocene, which coincided with a regional diagenetic key stratigraphic surface. The MTCs collapsed down from the steep mid- to upper-slope apron, partially draped the drift deposits, and flowed basinward over 10-20 km, extending over an area of approximately 400 km2.With the support of good-quality seismic reflection data, a detailed analysis was produced of the stratigraphic architecture of these MTCs, highlighting the high variability of the seismic facies from tabular bounded strata to chaotic patterns. The analysis of the facies demonstrated the internal stratigraphic complexity of the MTCs as well as that of the subsequent filling of the associated headwall scar-related depressions.A depositional reconstitution of the MTCs is proposed from collapse initiation to final deposition, resulting in the present-day irregular seafloor morphology. The model accounts for the influence of the Early Pliocene drift-induced topography on the distribution and internal architecture of the successive MTCs. Most likely due to sedimentation rate increase, the contourite displayed lateral morphological variations, forming flat to mound-shaped features when upslope collapses occurred. Depending on lee-side steepness, it then acted either as secondary décollement ramp or as natural obstacle for mass-wasting deposits.Strips of sharply-bounded chaotic facies preserved within the Pliocene contourite are interpreted as far-reaching fluid escape-related facies (thixotropy), resulting from frontal impact with the contourite at the toe of the MTCs.The MTCs are not unique mass-wasting carbonate deposits, as similar features with comparable dimensions have been reported in the geological record in the Bahamas and in other carbonate basins. However, they clearly illustrate a significant volume of sediment remobilization over short distances in carbonate slope environments.
(Sedimentary Geology. vol. 317, n° 0037-0738, pp. 27-42, 28/10/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS