Aout 2004 - Seasonal variations of a battery of biomarkers and physiological endpoints for the mussel Mytilus galloprovincialis transplanted into the Northwest Mediterranean Sea
Auteurs : Bodin N., Burgeot T., Stanisière J.Y., Bocquené G., Menard D., Minier C., Boutet I., Amat A., Cherel Y., Budzinski H.
Comparative Biochemistry and Physiology, Part B. 138 : 411-427.
Seasonal variations of six mussel ( Mytilus galloprovincialis) biomarkers at two sites in the Mediterranean Sea were compared with physiological indices (condition, growth and gonad maturation), environmental parameters (temperature, salinity and turbidity), and chemical contamination levels. The basal levels of acetylcholinesterase (AChE), DNA adducts, benzo[ a]pyrene hydroxylase (BPH), heat-shock proteins (HSP70), metallothioneins (MT) and P-glycoprotein (P-gp)-mediated multixenobiotic resistance (MXR) were estimated as early warning signals in caged mussels sampled at Carteau (native site) and La Fourcade (transplantation site) over a 2-year period. The Carteau and La Fourcade mussels have specific chemical contamination profiles but a similar range of values. For example, both are highly contaminated by heavy metals (201 and 258.4 mg kg-1 dw, respectively) and considered as moderately impacted for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). However, contamination levels at Carteau are twice as high for PAHs (101.5 mg g-1 dw) and PCBs (90.2 mg g-1 dw) than La Fourcade. The seasonal contamination trend at Carteau showed six-fold higher levels of pyrolytic pollutants in winter. Although few tissue lesions were detected in individuals studied at either site, greater parasitic infestation was observed at Carteau. The results of findings from the two Mediterranean pilot studies support the adaptability of transplanted mussels to be used as biomarkers and to establish physiological endpoints for chemical contaminant exposure.
Aout 2004 - Measurement of DNA adducts and strand breaks in dab (Limanda limanda) collected in the field : effects of biotic (age, sex) and abiotic (sampling site and period) factors on the extent of DNA damage
Auteurs : Akcha F., G. Leday, A. Pfohl-Leszkowicz
Mutation Research, Fundamental & Molecular Mechanisms of Mutagenesis 552:197-207
Aout 2004 - Measurement of single DNA strand breaks in gill and hemolymph cells of mussels, Mytilus sp, collected on the French Atlantic Coast
Auteurs : Akcha F., Tanguy A., Leday G., Pelluhet L., Budzinski H., Chiffoleau J-F.
Marine Environmental Research 58 : 753-756.
DNA single-strand breaks were measured by the comet assay in both gill and hemolymph cells of mussels collected in 3 sampling areas of the French coast (Pointe du Castelli, Pen Bron and Saint-Nazaire Harbour). Whole mussel tissue samples were also collected for the chemical determination of PAH, PCB and heavy metal concentrations.
In mussel, a higher level of DNA strand breaks was measured in gill than in hemolymph cells ( p<0.001). Despite a factor of contamination from 2 to 3 between sites, no difference in the extent of mussel DNA strand breaks was shown between sampling locations ( p>0.05), questioning the sensitivity of the assays used in biomonitoring studies.
Keywords : Mussel, DNA damage, Strand breaks, Comet, Oxidative stress
Juillet 2004 - Susceptiblity of larval Crepidula fornicata to predation by suspension-feeding adults
Auteurs : Pechenik J.A., Blanchard M., Rotjan R.
The slipper shell snail Crepidula fornicata forms dense assemblages along much of the European coast, where it co-occurs with oysters. We examined the susceptibility of slipper shell larvae to predation by suspension-feeders, including adults of their own species. In particular, we compared filtration rates on phytoplankton with those on larvae, and determined the extent to which consumption of larvae varied with adult size, larval size, and with the presence of alternative food (phytoplankton). We also examined the ability of competent larvae to metamorphose successfully in the presence of feeding adults. For each experiment, adults were held in plastic jars with seawater or phytoplankton suspension and allowed to graze on larvae (101 larvae per jar) for 4-6 h at room temperature (21-23degreesC); larvae were kept in circulation with gentle aeration. Adults of C. fornicata ingested substantial numbers of larvae over the complete range of sizes tested, about 450-850 mum shell length. Ingestion rates were reduced by 43-50% in the presence of phytoplankton, and were not correlated with adult shell length. The rates at which larvae were removed by adult slipper shells were generally lower than predicted from the rates at which the same adults ingested phytoplankton, suggesting either some ability of larvae to avoid capture or some difficulty of adults in consuming larvae entrained into their feeding currents. Slipper shell larvae were also readily consumed by adult oysters (Ostrea edulis and Crassostrea gigas), and indeed oysters consumed larvae at faster rates than predicted from their phytoplankton ingestion rates. Nevertheless, substantial numbers of competent larvae managed to metamorphose successfully during the test periods, either on the sides of the jars they were in or on the adults' shells, suggesting that recruitment probably continues in the field even when suspension-feeding adults are at high concentrations in the benthos.
Keywords : Larvae, Predation, Susceptibility
Juillet 2004 - Influence of oil exposure on the physiology and ecology of the common sole Solea solea : experimental and field approaches
Auteurs : Claireaux G., Désaunay Y., Akcha F., Aupérin B., Bocquené G., Budzinski H., Cravedi J.P., Davoodi F., Galois R., Gilliers C., Goanvec C., Guérault D., Imbert N., Mazéas O., Nonotte G., Nonotte L., Prunet P., Sébert P., Vettier A.
L'évaluation des conséquences écologiques d'une marée noire est un problème complexe qui requiert un examen articulé et cohérent de la chaîne d'interactions qui relie l'échelle cellulaire, à laquelle agit le contaminant, à l'échelle écosystémique, où se situent les interactions avec les activités humaines. Cette chaîne d'interactions traverse les frontières des disciplines scientifiques (chimie, toxicologie, physiologie, écologie halieutique). En prenant la sole (Solea solea L.) comme espèce cible - espèce caractéristique des habitats côtiers pollués par l'"Erika" - le programme de recherche ECTOPHY est une première tentative de mise en place d'une approche multidisciplinaire visant à définir, valider et mettre en relation des indicateurs d'intégrité fonctionnelle caractérisant les différents niveaux biologiques. Le couplage d'observations in situ avec des expositions en milieu contrôlé a montré que des pertes de fonctionnalité évidentes et durables à l'échelle de l'individu sont masquées à l'échelle de la population. Certaines des approches (in situ ou expérimentale) et certains des indicateurs testés peuvent être proposés comme instruments utilisables dans le cadre d'évaluation d'impact de pollutions par des hydrocarbures.
Evaluating the ecological impact of an oil spill is a complex issue requiring coherently articulated examination of the sequence of interactions that link the cell, where contaminants exert their effects, to the ecosystem, where interactions with human activities arise. This sequence of interactions traverses the frontiers between scientific disciplines (chemistry, toxicology, physiology, and fisheries ecology). Using the common sole (Solea solea L.) as a model species for the coastal habitats polluted by the "Erika" oil spill, our research project attempted to define indices of functional integrity that characterised the consequences of fuel exposure at the different biological levels. The coupling of field observations with experimental laboratory work revealed how functional alterations which are readily observable within individuals and their organs are progressively obscured as investigation progresses towards more complex organisational levels. Some of the approaches and indices are proposed as instruments for evaluating the impact of contamination by hydrocarbons.
Keywords : Common-sole, Physiological-ecology, Oil-spill, Complex-system-approach
Mai 2004 - Evaluation of biomarkers in oyster larvae in natural and polluted conditions
Auteurs : Damiens G., His E., Gnassia-Barelli M., Quiniou F., Roméo M
Crassostrea gigas D-shaped larvae were subjected to different conditions of temperature and salinity for 24 h and four biomarkers (acetylcholinesterase (AChE) activity, thiobarbituric acid reactive substances (TBARS) levels, glutathione S-transferase (GST) and catalase (CAT) activities) were measured. AChE activity decreased when salinity increased from 25 to 30 and 35 psu at 20 and 25 °C. Temperature did not seem to have an influence on AChE activity. TBARS levels increased as a function of salinity when the temperature was maintained at 20 °C, whereas at 25 °C no effect of salinity could be observed. Variations in GST and CAT activities were not significant with salinity and temperature except that catalase activity was higher at 25 °C than at 20 °C. Exposure experiments were conducted at 23 °C and 30 psu with carbofuran (100 and 1000 µg/l) and malathion (100 and 300 µg/l). There was an inhibition of AChE activity with carbofuran, and a toxic effect shown by an increase in TBARS levels counteracted by increases in GST and CAT activities which protected the larvae. When two pairs of adults producing larvae were taken into consideration, significant differences in biomarker levels were noted between the larval offspring of each pair. Malathion induced a decrease in AChE activity and an increase in CAT activity.
Keywords : Biomarker, Mollusc larvae, Crassostrea gigas, Abiotic factors, Carbofuran, Malathion
Avril 2004 - Anthropogenic regulation of the phosphorus balance in the Thau catchment–coastal lagoon system (Mediterraean Sea, France) over 24 years
Auteurs : La Jeunesse I ., Elliott M.
Marine Pollution Bulletin 48, 679–687
Novembre 2003 - Modélisation des flux sédimentaires charriés dans la baie du Mont-Saint-Michel (Manche, France)
Auteurs : Axel Ehrhold (Ifremer), Sylvie Guillou (Ecole), J. Auffret (Université de Caen), T. Garlan (Ifremer), K. Nguyen (Université de Caen)
Cette étude des flux sédimentaires en baie du Mont-Saint-Michel combine l'utilisation d'un modèle numérique 2DH résolvant les équations de Saint-Venant et un modèle des transits sédimentaires établis sur l'analyse des levés d'imagerie acoustique calibrée par un canevas dense de prélèvements sédimentaires. Les simulations des flux sédimentaires aux abords du Mont-Saint-Michel montrent le cheminement des sables coquilliers depuis les fonds subtidaux au large de la côte de Saint-Malo jusqu'aux encablures du Mont-Saint-Michel à l'est et la région de Cancale à l'ouest. Ce transfert des sédiments à la côte est à l'origine de la construction du prisme holocène dans cette région. Le modèle physique reproduit la dynamique tidale des sédiments aux abords immédiats du Mont-Saint-Michel sous le jeu de l'asymétrie des courants de marée et montre l'intérêt du couplage modèle numérique/dynamique de terrain dans la compréhension des processus de comblement des baies de la façade Manche-Atlantique.
A study of the sediment bedload in the Mont-Saint-Michel bay is presented here. It combines the use of a 2DH numerical model and a pattern of sediment bedload transport established on the analysis of the statements of sidescan imagery combined with a dense groundwork of sedimentary grab samples. Results show the role of tidal currents asymetry in the realistic bioclastic sand transfert from the subtidal environment to the coast and the divergence of sedimentary dynamic between the maritime bay to the West and the tidal delta to the East. This in-shore transfer is responsable of the Holocene prism construction. The model reproduces tidal sedimentary dynamics with the immediate surroundings of the Mont-Saint-Michel. It shows the interest of the modeling of bedload flows in the reconstitution of the sedimentary processes in the filling bays of Manche-Atlantic coast. (C) 2003 Editions scientifiques et medicales Elsevier SAS and Ifremer/CNRS/IRD. Tous droits reserves.