Regarding molluscs, PCB concentrations on a wet weight basis
were significantly different between species and correlated with
lipid percentage (p < 0.05); thus, PCBs concentrations in limpets
S. lessoni and bivalves B. rodriguezii are presented on a lipid basis in
Table 2. Mean concentrations of total PCB ranged from 1074 (±290)
to 1894 ± (520) ng g1 lipid wt in limpets S. lessoni and from 1903
(±580) to 4583 (±300) ng g1 lipid wt in B. rodriguezii, being
significantly higher in B. rodriguezii (p < 0.05). Zhao et al. (2005)
suggested that different trophic habits could explain differential
bioaccumulation in molluscs. This could be the case since
B. rodriguezii are filter feeders while S. lessoni are grazers of micro
and macroalgae. In addition, mussels would have higher uptake
since they breathe through gills whilst limpets are pulmonated.
However, different physiological mechanisms of each species such
as contaminant biotransformation or depuration cannot be
neglected (Barron, 1990).