Transferts et accumulations sur les marges du Golfe de Gascogne : architecture, fonctionnement et contrôles.
Ce travail présente une analyse de la morphologie et de la dynamique sédimentaire des systèmes turbiditiques actuels du Cap-Ferret et de Capbreton (sud du Golfe de Gascogne). La reconnaissance effectuée sur le système de Capbreton est la première à le considérer dans son ensemble. Ce travail se base sur des données acoustiques de subsurface (sondeur multifaisceaux, sondeur de sédiments Chirp) et de carottages issues de la campagne océanographique Sargass menée par l’Université de Bordeaux. L’analyse morpho-bathymétrique révèle l’organisation amont-aval des géométries sédimentaires dans ces systèmes et, couplée aux données sédimentaires, de préciser les processus de dépôts liés aux écoulements gravitaires. Le fonctionnement holocène du canyon de Capbreton montre des processus gravitaires haute fréquence, révélant son rôle de dépôt-centre pour le sud du golfe de Gascogne. Dans le système du Cap-Ferret, la zone de transition chenal-lobe a été investiguée à fine échelle, documentant ainsi des structures sédimentaires rarement identifiées avec ce niveau de détails dans les systèmes turbiditiques modernes. La dynamique sédimentaire de chacun de ces systèmes est soumise à des forçages auto-cycliques et glacio-eustatiques qui affectent chacun des systèmes de façons différentes. Ces informations ont permis de proposer un modèle régional de fonctionnement sédimentaire au cours des derniers 50 000 ans.
(08/07/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The silicon isotope composition of Ethmodiscus rex laminated diatom mats from the tropical West Pacific: Implications for silicate cycling during the Last Glacial Maximum
The cause of massive blooms of Ethmodiscus rex laminated diatom mats (LDMs) in the eastern Philippine Sea (EPS) during the Last Glacial Maximum (LGM) remains uncertain. In order to better understand the mechanism of formation of E. rex LDMs from the perspective of dissolved silicon (DSi) utilization, we determined the silicon isotopic composition of single E. rex diatom frustules (δ 30 Si E. rex) from two sediment cores in the Parece Vela Basin of the EPS. In the study cores, δ 30 Si E. rex varies from À1.23‰ to À0.83‰ (average À1.04‰), a range that is atypical of marine diatom δ 30 Si and that corresponds to the lower limit of reported diatom δ 30 Si values of any age. A binary mixing model (upwelled silicon versus eolian silicon) accounting for silicon isotopic fractionation during DSi uptake by diatoms was constructed. The binary mixing model demonstrates that E. rex dominantly utilized DSi from eolian sources (i.e., Asian dust) with only minor contributions from upwelled seawater sources (i.e., advected from Subantarctic Mode Water, Antarctic Intermediate Water, or North Pacific Intermediate Water). E. rex utilized only ~24% of available DSi, indicating that surface waters of the EPS were eutrophic with respect to silicon during the LGM. Our results suggest that giant diatoms did not always use a buoyancy strategy to obtain nutrients from the deep nutrient pool, thus revising previously proposed models for the formation of E. rex LDMs.
(Paleoceanography. vol. 30, n° 0883-8305, pp. 803-823, 01/07/2015)
UC, RWTH Aachen, MSI, UC Santa Barbara - UCSB, UC, UCLouvain, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Occurrence of pharmaceutical compounds and pesticides in aquatic systems
This paper deals with the detection and quantification of APIs and other priority substances in the Arade River estuary (Portugal) providing the usefulness of Polar Organic Compound Integrative Samplers (POCIS). Thirteen APIs were detected whose variation was site and time dependent. Caffeine was at the highest concentration (804 ± 209 ng/L) followed by theophylline (184 ± 44 ng/L). Other APIs were analgesic, anticonvulsant, non-steroidal anti-inflammatory drugs, anti-lipidemic, anxiolytic and antidepressants. Twenty pesticides comprising atrazine, diuron, isoproturon, terbutryn and simazine included in the Water Framework Directive priority list were also site and time dependent. Carbendazim occurred at the highest concentration (45 ± 18 ng/L at site 1) but atrazine, diuron, isoproturon and simazine levels were below the Environmental Quality Standards. Although the summer impact was unclear, the results highlighted POCIS suitability for profiling these contaminants. This is to our knowledge the first study concerning APIs and pesticides in this area.
(Marine Pollution Bulletin. vol. 96, n° 0025-326X, pp. 384-400, 01/07/2015)
UAlg, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Responses of cytochrome P450, GST, and MXR in the mollusk Corbicula fluminea to the exposure to hospital wastewater effluents
Pharmaceutical products are a major group of chemical compounds that are continuously released into the environment. The primary pathway of pharmaceuticals to the aquatic environment is the discharge of wastewater effluents. The Psychiatric hospital of Montpon (Dordogne, France) operates with its wastewater treatment plant. We first evaluated the presence and concentrations of 27 pharmaceuticals compounds in these effluents. All of the 27 compounds were detected in these wastewater effluents at concentrations ranging between 37,500 ng L−1 (paracetamol) and 150 ng L−1 (citalopram). The aim of the study was then to evaluate the exposure effects of the effluents on cytochrome P450, GST, and MXR responses in Corbicula fluminea gills and digestive glands. Experiments on clams exposed during 1, 3, 7 14, and 21 days revealed a strong and continuous overexpression of mdr1 (multidrug resistant 1) gene expression in gills and transitory variations in pi-gst expression and GST activity. EROD activity increased also transitory after 1 day in the digestive gland of exposed clams. These results indicated that in the effluent, some molecules have undergone metabolism of phase 1 and/or phase 2.
(Environmental Science and Pollution Research. vol. 22, n° 0944-1344, pp. 11033-11046, 01/07/2015)
VAcBio, INUC, Comue de Toulouse, LECA, UJF, USMB [Université de Savoie] [Université de Chambéry], CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INUC, Comue de Toulouse, GEODE, UT2J, Comue de Toulouse, CNRS
Genotoxic and immunotoxic potential effects of selected psychotropic drugs and antibiotics on blue mussel (Mytilus edulis) hemocytes.
The potential toxicity of pharmaceuticals towards aquatic invertebrates is still poorly understood and sometimes controversial. This study aims to document the in vitro genotoxicity and immunotoxicity of psychotropic drugs and antibiotics on Mytilus edulis. Mussel hemocytes were exposed to fluoxetine, paroxetine, venlafaxine, carbamazepine, sulfamethoxazole, trimethoprim and erythromycin, at concentrations ranging from μg/L to mg/L. Paroxetine at 1.5 μg/L led to DNA damage while the same concentration of venlafaxine caused immunomodulation. Fluoxetine exposure resulted in genotoxicity, immunotoxicity and cytotoxicity. In the case of antibiotics, trimethoprim was genotoxic at 200 μg/L and immunotoxic at 20 mg/L whereas erythromycin elicited same detrimental effects at higher concentrations. DNA metabolism seems to be a highly sensitive target for psychotropic drugs and antibiotics. Furthermore, these compounds affect the immune system of bivalves, with varying intensity. This attests the relevance of these endpoints to assess the toxic mode of action of pharmaceuticals in the aquatic environment.
(Environmental Pollution. vol. 202, n° 0269-7491, pp. 177-186, 01/07/2015)
INRS-AFSB, INRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, UB
Etude expérimentale des effets des conditions environnementales (température, oxygène, polluants) sur la survie, le développement et le comportement des stades embryo-larvaires d'esturgeon européen, Acipenser sturio
L'esturgeon européen Acipenser sturio est un poisson migrateur amphihalin qui a connu un fort déclin au cours du 20ème siècle. La dernière population vit dans le bassin Gironde-Garonne-Dordogne (GGD) et sa dernière reproduction connue date de 1994. Les individus relachés lors de repeuplements sont supposés venir se reproduire prochainement. Du fait du changement global et de l'évolution des activités humaines, une meilleure connaissance de la vulnérabilité des jeunes stades de A. sturio vis-à-vis de la température, de la disponibilité en oxygène et des polluants s'est avérée nécessaire. La sensibilité aux conditions oxythermiques actuelles et à venir a été évaluée ainsi que la qualité des sédiments des frayères. Enfin, la sensibilité des jeunes stades de cette espèce à des mélanges de polluants représentatifs du bassin GGD a été également évaluée. Une forte sensibilité des jeunes stades de A. sturio au taux d'oxygène a été mise en évidence. Les fenêtres optimales et critiques de tolérance ont été estimées. La toxicité des sédiments de frayères de Dordogne est globalement supérieur à celle des sédiments de frayères de Garonne. Beauregard et Pessac-sur-Dordogne semblent être respectivement les sites les plus favorables et défavorables aux jeunes stades. La sensibilité de A. sturio aux polluants rencontrés dans le bassin est relativement faible. Les conditions environnementales actuelles du bassin GGD semblent globalement satisfaisantes pour accueillir le développement de jeunes stades de A. sturio. Les données collectées dans cette étude pourront servir pour d'autres programmes de réintroduction de cette espèce.
(pp. 222, 25/06/2015)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Velocity estimation of valve movement in oysters for water quality surveillance
The measurements of valve opening activity in a population of oysters under natural environmental conditions are used to estimate the velocity of their valve movement activity. Three different differentiation schemes were used to estimate the velocity, namely an algebraic-based differentiator method, a non-homogeneous higher order sliding mode differentiator and a homogeneous finite-time differentiator. The estimated velocities were then used to compare the performances of these three different differentiators. We demonstrate that this estimated velocity can be used for water quality monitoring as the differentiators can detect very rapid change in valve movements of the oyster population resulting from some external stimulus or common input.
(24/06/2015)
NON-A, Inria, CRIStAL, CNRS, CRIStAL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The mussel caging approach in assessing biological effects of wastewater treatment plant discharges in the Gulf of Finland (Baltic Sea)
Biological effects of wastewater treatment plant (WWTP) effluents were investigated in Baltic mussels (Mytilus trossulus) caged for one month 800 m and 1100 m from the WWTP discharge site and at a reference site 4 km away. Significant antioxidant, genotoxic and lysosomal responses were observed close to the point of the WWTP discharge. Passive samplers (POCIS) attached to the cages indicated markedly higher water concentrations of various pharmaceuticals at the two most impacted sites. Modeling the dispersal of a hypothetical passive tracer compound from the WWTP discharge site revealed differing frequencies and timing of the exposure periods at different caging sites. The study demonstrated for the first time the effectiveness of the mussel caging approach in combination with passive samplers and the application of passive tracer modeling to examine the true exposure patterns at point source sites such as WWTP pipe discharges in the Baltic Sea.
(Marine Pollution Bulletin. vol. 97, n° 0025-326X, pp. 135-149, 24/06/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Transcriptomic, Biochemical, and Histopathological Responses of the Clam Ruditapes decussatus from a Metal-Contaminated Tunis Lagoon
This study was designed to investigate the molecular (transcriptional expression), biochemical (oxidative stress and neurotoxicity), and histopathological effects of metal contamination in the gill of clams (Ruditapes decussatus) sampled from the Tunis lagoon. The concentrations of five heavy metals (Cd, Pb, Hg, Cu, and Zn) in surface sediments and their accumulation in soft tissues of R. decussatus were evaluated in three sites (Z1, Z2, and Z3). A metal contamination state of Tunis lagoon sediments was noted with spatial variations with relatively high levels at Z2. Biomarker analyses showed an increase in glutathione S-transferase and catalase activities and lipid peroxidation levels and a decrease in acetylcholinesterase activity in the studied sites. Molecular investigation showed a significant overexpression of: cytochrome c oxidase subunit I, ribosomal RNA 16S, Cu/Zn superoxide dismutase, heat shock protein 70, and metallothioneins in the three sampling sites. Moreover, our data were correlated to severe and diverse histopathological alterations in the clam gills. The principal component analysis showed that the Z2 region is more affected by metal contamination than Z1 and Z3 regions. Current field results suggest the use of several combined biomarkers at different cell levels instead of individual ones in monitoring programs.
(Archives of Environmental Contamination and Toxicology. vol. 70, n° 0090-4341, pp. 241-256, 16/06/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Recovery capabilities of Xenopus laevis after exposure to Cadmium and Zinc
The present investigation evaluates the recovery capabilities of Xenopus laevis following 12days of exposure to 30μg CdL(-1) and 1000μg ZnL(-1) alone or mixed, followed by a depuration phase in laboratory conditions. Focused endpoints, which were investigated at different times of depuration, are bioaccumulation of Cd and Zn, micronucleus induction, quantification of metallothioneins (MTs), and expression of genes involved in metal toxicity mechanisms. The results show that at the end of the contamination phase, there was higher metal bioaccumulation capability and MT synthesis in remaining tissues than in the liver. An increased expression of genes involved in detoxification and oxidative stress mechanisms was observed, suggesting an additive effect of both metals and a higher Zn regulation in the liver. During the depuration phase, the results show the recovery capability of Xenopus from 7days of depuration related to metamorphosis processes, which were observed at the end of the experiment. The results confirm the relevance of the amphibian model and the complementarities between a marker of genotoxicity, MT production, bioaccumulation and transcriptional analysis in the evaluation of the ecotoxicological impact. The results also highlight the reversible effects of Cd and Zn toxicity.
(Chemosphere. vol. 139, n° 0045-6535, pp. 117-125, 11/06/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS