Limpets Siphonaria lessoni (10e12 mm) and mussels Brachidontes
rodriguezii (17e20 mm) were manually collected at the
rocky intertidal area of each study area. Approximately 20 organisms
from each site were carried refrigerated to the laboratory and
kept on aerated tanks with seawater of the same area to depurate.
After 24 h, shell length was measured and soft tissues were
dissected, rinsed thoroughly with Milli-Q water and pooled. Subsamples
of soft tissues were dried in an oven at 60 C and then
ground up with a mortar and pestle for the stable isotopes analysis.
For PCB analysis, soft tissues were homogenized with a stainless
steel blender and stored at 20 C until analysis.