Brachidontes variabilis and Patella sp. as quantitative biological indicators for cadmium, lead and mercury in the Lebanese coastal waters

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 × 103 to 3.4 × 104, from 7.5 × 103 to 8.0 × 103 and from 3.0 × 104 to 3.2 × 104, for Cd, Pb and Hg, respectively. For limpets, BCFs varied from 1.7 × 104 to 7.4 × 104 for Cd, from 2.5 × 103 to 6 × 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.