The open sea as the main source of methylmercury in the water column of the Gulf of Lions (Northwestern Mediterranean margin)
Despite the ecologic and economical importance of coastal areas, the neurotoxic bioaccumulable monomethylmercury (MMHg) fluxes within the ocean margins and exchanges with the open sea remain unassessed. The aim of this paper is to address the questions of the abundance, distribution, production and exchanges of methylated mercury species (MeHgT), including MMHg and dimethylmercury (DMHg), in the waters, atmosphere and sediments of the Northwestern Mediterranean margin including the Rhône River delta, the continental shelf and its slope (Gulf of Lions) and the adjacent open sea (North Gyre).
(Geochimica et Cosmochimica Acta, n° 0016-7037, 01/02/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, OOB, UPMC, CNRS
Novel histone deacetylase 6 (HDAC6) selective inhibitors: a patent evaluation (WO2014181137)
(Expert Opinion on Therapeutic Patents. vol. 27, n° 1354-3776, pp. 229-236, 31/01/2017)
UNIL, UNIGE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IC2MP [Poitiers], UP, INC-CNRS, CNRS
Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach
While the Atlantic Meridional Overturning Circulation (AMOC) is thought to be a crucial component of the North Atlantic climate, past changes in its strength are challenging to quantify, and only limited information is available. In this study, we use a perfect model approach with the IPSL-CM5A-LR model to assess the performance of several surface nudging techniques in reconstructing the variability of the AMOC. Special attention is given to the reproducibility of an extreme positive AMOC peak from a preindustrial control simulation. Nudging includes standard relaxation techniques towards the sea surface temperature and salinity anomalies of this target control simulation, and/or the prescription of the wind-stress fields. Surface nudging approaches using standard fixed restoring terms succeed in reproducing most of the target AMOC variability, including the timing of the extreme event, but systematically underestimate its amplitude. A detailed analysis of the AMOC variability mechanisms reveals that the underestimation of the extreme AMOC maximum comes from a deficit in the formation of the dense water masses in the main convection region, located south of Iceland in the model. This issue is largely corrected after introducing a novel surface nudging approach, which uses a varying restoring coefficient that is proportional to the simulated mixed layer depth, which, in essence, keeps the restoring time scale constant. This new technique substantially improves water mass transformation in the regions of convection, and in particular, the formation of the densest waters, which are key for the representation of the AMOC extreme. It is therefore a promising strategy that may help to better constrain the AMOC variability and other ocean features in the models. As this restoring technique only uses surface data, for which better and longer observations are available, it opens up opportunities for improved reconstructions of the AMOC over the last few decades.
(Climate Dynamics, n° 0930-7575, pp. 1-17, 25/01/2017)
LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, UOR, PARVATI, LOCEAN, IPSL, ENS-PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, OCCR, UNIBE
Effects of PVP/PEI coated and uncoated silver NPs and PVP/PEI coating agent on three species of marine microalgae
In the last years, applications for silver nanoparticles (Ag NPs) continue to increase together with the concerns about their potential input and hazards in aquatic ecosystems, where microalgae are key organisms. The aim of the present study was to assess the relative sensitivity of three marine microalgae species with differences in cell wall composition/structure exposed to Poly N-vinyl-2-pirrolidone/Polyethyleneimine (PVP/PEI) coated 5 nm Ag NPs and uncoated 47 nm Ag NP. As limited attention has been paid to the role of coating agents in NP toxicity, the effect of PVP/PEI alone was also evaluated. After 72 h in artificial seawater, 47 nm Ag NPs formed around 1400 nm size aggregates while PVP/PEI coated 5 nm Ag NPs reached around 90 nm. Ag+ release in seawater was around 3% for 47 nm Ag NPs and 30% for PVP/PEI coated 5 nm Ag NPs. PVP/PEI coated 5 nm Ag NP aggregates entrapped the algal cells in a network of heteroaggregates, while uncoated 47 nm Ag NPs interacted to a lesser extent with algae. The concentration of PVP/PEI coated 5 nm Ag NPs that exerted the median effect (EC50) on algae growth pointed out differences in algae sensitivity: T. suecica was about 10 times more sensitive than I. galbana and P. tricornutum. Further, the coating agent alone was as toxic to algae as PVP/PEI coated 5 nm Ag NPs, suggesting that presence of the coating agent was the main driver of toxicity of coated NPs. Uncoated 47 nm Ag NPs instead, showed similar toxicity towards algae although P. tricornutum was slightly less sensitive than T. suecica and I. galbana, which agrees with the presence of a resistant silicified cell wall in the diatom. The present work demonstrates differences in sensitivity of three marine microalgae, possibly related to their cell surface and size characteristics.
(Science of the Total Environment. vol. 577, n° 0048-9697, pp. 45-53, 15/01/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Lacustrine record of last millennia eruptions in Northern Chilean Patagonia (45–47°S)
(The Holocene. vol. 27, n° 0959-6836, pp. 1227 - 1251, 10/01/2017)
ULiège, ULiège, LMV, UBP, INSU - CNRS, UJM, UJM EPE, CNRS, GEOTOP, UQAM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UdeC, ULiège, UdeC
Identification of the Molecular Clockwork of the Oyster Crassostrea gigas
Molecular clock system constitutes the origin of biological rhythms that allow organisms to anticipate cyclic environmental changes and adapt their behavior and physiology. Components of the molecular clock are largely conserved across a broad range of species but appreciable diversity in clock structure and function is also present especially in invertebrates. The present work aimed at identify and characterize molecular clockwork components in relationship with the monitoring of valve activity behavior in the oyster Crassostrea gigas. Results provided the characterization of most of canonical clock gene including clock, bmal/cycle, period, timeless, vertebrate-type cry, rev-erb, ror as well as other members of the cryptochrome/photolyase family (plant-like cry, 6–4 photolyase). Analyses of transcriptional variations of clock candidates in oysters exposed to light / dark regime and to constant darkness led to the generation of a putative and original clockwork model in C. gigas, intermediate of described systems in vertebrates and insects. This study is the first characterization of a mollusk clockwork. It constitutes essential bases to understand interactions of the different components of the molecular clock in C. gigas as well as the global mechanisms associated to the generation and the synchronization of biological rhythms in oysters.
(PLoS ONE. vol. 12, n° 1932-6203, pp. e0169790, 10/01/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Active tectonics of the Calabrian subduction revealed by new multi-beam bathymetric data and high-resolution seismic profiles in the Ionian Sea (Central Mediterranean)
The detailed morphology and internal structure of the Calabrian accretionary wedge and adjacent Eastern Sicily margin are imaged in unprecedented detail by a combined dataset of multi-beam bathymetry and high-resolution seismic profiles. The bathymetric data represent the results of 6 recent marine geophysical surveys since 2010 as well as a compilation of earlier surveys presented as a 2 arc-sec (60 m) grid. Several distinct morpho-tectonic provinces are identified including: the deeply incised Malta–Hyblean Escarpment, numerous submarine canyons, broad regions of relatively flat seafloor dominated by fields of sediment waves, the gently undulating anticlinal fold-and-thrust belts of the external Calabrian accretionary wedge and the adjacent portion of the Western Mediterranean Ridge. The Calabrian arc can be divided into 4 domains (from SE to NW): 1) the undeformed Ionian abyssal plain, 2) the external evaporitic wedge, 3) the internal clastic wedge, 4) the Calabrian backstop (Variscan crystalline basement). The Calabrian accretionary wedge can also be divided laterally into two major lobes, the NE- and the SW lobes, and two minor lobes. The kinematics of the limit between the two major lobes is investigated and shown to be sinistral in the external (evaporitic) wedge. A network of radial slip lines within the southernmost external wedge unequivocally demonstrate ongoing dextral displacement of a rigid indenter (representing the corner of the clastic wedge) into the evaporitic wedge thereby confirming the geodynamic model of an active lateral slab tear fault here off eastern Sicily. The slab tear produces a series of major sub-parallel dextral strike-slip faults offshore Mt. Etna and south of the Straits of Messina consistent with the relative motions between Calabria and the Peloritan domain (NE Sicily). Abundant strike-slip faulting, and wide-spread folding and thrusting observed throughout the entire accretionary wedge, indicate regional shortening between the Ionian abyssal plain (foreland) and the Calabrian–Peloritan backstop caused by active subduction.
(Earth and Planetary Science Letters. vol. 461, n° 0012-821X, pp. 61 - 72, 02/01/2017)
LDO, INSU - CNRS, UBO EPE, CNRS, GEOMAR, CAU, MARUM, SHOM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER, INSU - CNRS, UM, CNRS, UA, CNR, GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], UniCA, ICREA, UTM
Fate of antibiotics from hospital and domestic sources in a sewage network
(Science of the Total Environment. vol. 575, n° 0048-9697, pp. 758-766, 01/01/2017)
METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, HCMUT, VNU-HCM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Inputs, dynamics and potential impacts of silver (Ag) from urban wastewater to a highly turbid estuary (SW France)
Although silver (Ag) has been listed as a priority pollutant for the aquatic environment by the European Union (Directive 2006/11/EC), the use of Ag-based products with antimicrobial effects is increasing in Europe, as well as North America and Asia. This study investigates personal care products (PCP) as a potential source of Ag in wastewater, as well as the dynamics and fate of Ag in the influent and effluent of a major urban wastewater treatment plant (WWTP) located on the fluvial part of the Gironde Estuary. Typical household PCPs marked as using Ag contained concentrations of up to 0.4 mg kg−1 making them likely contributors to urban Ag released into the aquatic environment. Silver concentrations in influent wastewater generally occurred during mid-week working hours and decreased during the night and on weekends clearly indicating the dominance of urban sources. Up to 90% of the total Ag in wastewater was bound to particles and efficiently (>80%) removed by the treatment process, whereas 20% of Ag was released into the fluvial estuary. Silver concentrations in wastewater effluents clearly exceeded estuarine concentrations and may strongly amplify the local Ag concentrations and fluxes, especially during summer rainstorms in low river discharge conditions. Further work should focus on environmental effects and fate of urban Ag release due to immediate localized outfall and/or the adsorption on estuarine particles and subsequent release as dissolved Ag chloro-complexes within the estuarine salinity gradient
(Chemosphere. vol. 167, n° 0045-6535, pp. 501-511, 01/01/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Spatial patterns in the condition index of the wild Pacific oyster Crassostrea gigas in a macrotidal coastal ecosystem: Influence of tidal processes and beyond
In macrotidal coastal ecosystems, spatial heterogeneity of the water column properties is induced by both oceanic and continental influences. Hydrodynamic processes generate a land-sea gradient of environmental conditions, affecting the biological performances of sedentary organisms. The aim of the present study is to establish an extensive spatial assessment in the reproductive investment of the wild Pacific oyster Crassostrea gigas in Arcachon Bay. This is done by looking for a relationship between the Lawrence and Scott condition index (LSCI) and two tidal processes: the immersion level (IL) and the local oceanic flushing time (LoFt). The LSCI of C. gigas was assessed, just before gamete release, at 68 sampling stations in Arcachon Bay. Oyster performance was overall low and spatially variable. Significant differences in the LSCI were detected between the outer and inner bay. Oyster reefs located toward the mouth of the bay exhibited high LSCI (between 9 and 11), while oyster reefs located in inner bay, especially in south-eastern part around the Eyre River, had low LSCI (below 6). Linear modelling allowed to highlight significant effects of both tidal processes IL and LoFt on the obtained LSCI gradient. IL, LoFt explained 33% of the spatial variability observed on LSCI (IL = 3%; LoFt = 17%; LoFt + IL: 13%), 6% were attributed to the intra-station variation (ISv). Thus, high IL and rapid LoFt favor a better development of somatic-gonadal volume, probably because of longer feeding time and higher supply of food from the ocean by tide flows. Disentangling the effects of IL and LoFt on LSCI allowed to describe the spatial pattern in 61% of variability not explained by both tidal factors. A residual gradient directed southeast-northwest highlighted that others factors, independent from IL and LoFt seems to hamper inner bay oyster reproductive performance. Consequently, investigating on the ecological functioning (Eyre influences), trophic potential and anthropogenic pressures of this zone seem crucial on the understanding of C. gigas reproductive pattern in Arcachon Bay.
(Journal of Sea Research (JSR). vol. 119, n° 1385-1101, pp. 28-36, 01/01/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, IFREMER