The mussel, Brachidontes variabilis, and the limpet, Patella sp., were used as indicators to monitor cadmium, lead and mercury concentrations along the Lebanese coast. Studies were carried out in order to define the best strategy for assessing and minimizing the effects of size and physiological condition on the metal contents of the molluscs, and corrective models were constructed. Metal concentrations in surface water were measured to estimate bioconcentration factors (BCFs). The BCFs varied from 8.3 x 10(3) to 3.4 x 10(4), from 7.5 x 10(3) to 8.0 X 10(3) and from 3.0 x 10(4) to 3.2 x 10(4), for Cd, Pb and Hg, respectively. For limpets, BCFs varied from 1.7 x 10(4) to 7.4 x 10(4) for Cd, from 2.5 x 10(3) to 6 x 103 for Pb and remained fairly constant at around 104 for Hg. The highest BCFs were associated with lowest contamination levels. The results of the geographical survey exhibited a similar large-scale spatial pattern for the two species and followed the metal concentration distributions measured in the waters.

Larval stages of bivalve molluscs are highly sensitive to pollutants. Oysters from a hatchery from Normandy (English Channel) were induced to spawn, and fertilized eggs were exposed to copper or cadmium for 24 h. Metal accumulation (from 0.125 to 5 mu g Cu L-1 and from 25 to 200 mu g Cd L-1) and MT concentrations were measured in larvae. Compared to controls, larvae accumulated copper and cadmium with an increase in MT concentrations particularly with cadmium (i.e. 130.96 ng Cu (mg protein)(-1) and 12.69 mu g MT (mg protein)(-1) at 1 mu g Cu L-1 versus 23.19 ng Cu (mg protein)(-1) and 8.92 mu g MT (mg protein)(-1) in control larvae; 334.3 ng Cd (mg protein)(-1) and 11.70 mu g MT (mg protein)(-1) at 200 mu g Cd L-1 versus 0.87 ng Cd (mg protein)(-1) and 4.60 mu g MT (mg protein)(-1) in control larvae). Larvae were also obtained from oysters of a clean area (Arcachon Bay) and a polluted zone (Bidassoa estuary) and exposed to copper in the laboratory, their MT concentration was measured as well as biomarkers of oxidative stress. Biomarker responses and sensitivity to copper for the larvae from Arcachon oysters were higher than for those from Bidassoa.

This study aimed at comparing toxic element (Hg, Cd) bioaccumulation in relation to age for bottlenose (Tursiops truncatus) and striped dolphins (Stenella coeruleoalba) from Mediterranean and Atlantic waters. Metal concentrations were also measured in selected prey to infer metal exposure through the diet. As expected, Mediterranean prey exhibited the highest Hg levels, probably as a consequence of the Hg enrichment of the Mediterranean Sea. Comparing the predators from each area and taking age into account, Mediterranean bottlenose dolphins displayed higher Hg levels than Atlantic dolphins (p = 0.032), whereas Mediterranean striped dolphins did not (p = 0.691). The consumption of Myctophid fish, which showed the highest Hg levels (105 +/- 80 ng g(-1) w.wt.) among Atlantic prey, may explain the high Hg levels in the liver of the Atlantic striped dolphins and suggested a preferential offshore feeding behaviour in this area. Concerning Cd, no clear differences were found between geographical areas. (c) 2006 Elsevier Ltd. All rights reserved.