No abstract

No abstract

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.

No abstract

No abstract

No abstract

Concentrations of Cd, Cu, Fe, Pb and Zn were measured in scales of the seagrass Posidonia oceanica from different areas of the French NW Mediterranean: the Cbte d'Azur and Corsica.Scales are basal parts of the seagrass which remain fixed on the rhizomes when leaves of P. oceanica die. Scales do not decay and the cyclic variation of their thickness permits retroactive dating (lepidochronology). Heavy metal concentrations were determined in the scales of P. oceanlca dated by lepidochronology. Scales from P. oceanica collected from the CBte d'Azur (analysis of lepidochronological years from 1982 to 1992) generally showed concentrations of Cu. Fe. Pb and Zn to be greater lharr those measured in samples from Corsica (analysis of lepidochronological years from 1972 to 1992).In contrast, Cd concentrations recorded in scales from Corsica were higher than in those from Cbte d'Azur. The reasons for these high Cd values are unknown. There was a general tendency for metal concentrations in P oceanlca scales collected on the C6te d'Azur to decrease with time. In Villefranchesur-Mer, where there are many pleasure boats, large concentrations of Cu were found in P. oceanica scales. These concentrations had increased in recent years.

No abstract