Polluants métalliques et chaînes alimentaires marines

Les concentrations en métaux traces (Cd, Cu, Hg, Pb et Zn) ont été déterminées à différents niveaux d'une chaîne alimentaire côtière de Méditerranée (phytoplancton, zooplancton, et crustacés nectoniques). La synthèse de nos résultats montre qu'en général les concentrations en métaux sont plus faibles dans les prédateurs que dans les proies. Cependant des poissons tels que le thon, la bonite et le congre présentent, selon différents auteurs, des concentrations en mercure plus fortes que celles des maillons inférieurs. Ce problème de contamination en mercure de certains poissons de Méditerranée (phénomène qui est peut-être naturel) reste posé. D'autre part, des déterminations de métaux traces, associées à des mesures de calcium total, ont été effectuées dans des zones de pollution reconnue sur des organes-cibles, les branchies de poissons et de moules. Ces organismes marins sont situés au sommet de chaînes alimentaires. Ces déterminations tendent à montrer que des analyses de calcium (faciles, rapides et peu onéreuses) pourraient servir d'indicateur de stress toxique général pour évaluer la pollution

Détermination de la qualité des eaux du littoral mauritanien par la mesure des métaux traces chez les mollusques

Les variations des concentrations en Cd, Cu, Fe, Mn et Zn ont été analysées chez deux Mollusques prélevés l'un le long de la côte mauritanienne (Donax rugosus) et l'autre dans deux baies du nord de la Mauritanie (Venus verrucosa). Pour D. rugosus, les poids variant, nous avons examiné les relations C = a Pb, C = concentration en métal, P = poids sec et b = coefficient de régression. Dans tous les cas, le coefficient b est négatif. Pour V verrucosa, les poids varient peu, V. verrucosa, animal le plus gros, a les concentrations les plus faibles en métaux, à l'exception du cadmium. Ce travail a été réalisé dans le cadre d'un accord inter-universitaire : Université de Nice,Institut Supérieur des Sciences de Nouakchott

Isolement, étude structurale et propriétés antibiotiques et antifongiques d'un composant polysaccharidique de la diatomée marine Cheatoceros Lauderi (Ralfs CC)

International audienceThe marine diatom Chaetoceros lauderi produces a high molecular weight ionic polysaccharide which exhibits a significant antibiotic activity against staphylococcus species acid pathogenic fungi. Acidic hydrolysis followed by GC-MS identification of the corresponding alditol acetates leads to a basic structural compotion comprising arabinose, xylose, galactorse, mannose and glucose in the ration 12:21:15:25:5. The presence of uronic and sulfate residues in the ratio 3:2 is suspected from the conductimetric titration curve using sodium hydroxyde

Heavy metal content and biotransformation enzymes in two fish species from the NW Mediterranean

Trace metal concentrations (Cd, Cu, Fe, Zn) and total-calcium content were measured in the gills of 2 marine fish (painted comber Serranus cabrilla and striped mullet Mullus barbatus) sampled in different stations in the cove of Cortiou, where the outlet collecting the waste waters of Marseille, France, is situated (NW Mediterranean). In parallel, the activity rates of some phase I enzymes (ethoxyresorufin-0-dealkylase, EROD; pentoxyresorufin-0-dealkylase, PROD) and phase II enzymes (glutathione-S-transferase, GST) were determined in the livers of both species of fish. Cadmium and copper concentrations were highly variable for both species. Two sampling stations situated in the dispersion area of waste waters seemed affected by chemical pollution. At these stations, iron concentrations appeared to be higher in gills of S. cabrilla and M. barbatus. Elevated iron concentrations were thought to be due to the water treatment plant, which uses iron chloride as a flocculant. Likewise, at both stations calcium and cadmium concentrations were higher in M barbatus. EROD and PROD activities appeared to be generally lower in the livers of S. cabrilla collected at both 'polluted' stations; GST activities did not differ according to the sampling stations. Enzyme activities (PROD and GST) in M barbatus were lower at the stations in the dispersion area of waste waters. The results imply that heavy metals, which can also be accumulated in some target organs of fish, may lower biotransformation enzyme activities which are induced in the livers of fish exposed to organics

Biomarkers in Ruditapes decussatus: a potential bioindicator species

The clam Ruditapes decussatus is distributed worldwide and due to its ecological and economical interest has been proposed as a bioindicator in areas where mussels are not available. The accumulation of several anthropogenic compounds in their tissues suggests that they possess mechanisms that allow them to cope with the toxic effects of these contaminants. Besides pollutant uptake, the use of biomarkers is pointed out in this paper since it is a promising approach to monitor the effect of these contaminants in the marine environment. Biomarkers complement the information of the direct chemical characterization of different types of contaminants. Therefore, the aim of this paper is to review the role of several biomarkers: (metallothioneins (MT), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx) (total and selenium-dependent), lipid peroxidation (measured as MDA, one of the final products of lipid peroxidation), glutathione S-transferase (GST) and acetylcholinesterase (AChE), measured in different tissues of the clam R. decussatus, in laboratory conditions and under various environmental stresses, in two ecosystems (Ria Formosa lagoon- Portugal) and Bizerta lagoon (Tunisia) in a perspective of a multibiomarker approach to assess environmental changes. Experiment and field studies are in good agreement since MT levels, especially in the gills, the first target tissue of these contaminants, can be used as biomarker of exposure to Cd. GPx and MDA may also be determined in this respect. AChE activity is inhibited by pesticide and, to a less extent, by metal exposure in the gills and whole soft body of clams. However, the induction of GST isoforms experimentally demonstrated is not observed in the field because only global GST activity was determined. The whole set of results opens new research perspectives for the use of this species to assess the effect of mixtures of pollutants in the aquatic environment.PAUILF (Programme d’Action Universitaire Integreée Luso-Françaiseinfo:eu-repo/semantics/publishedVersio