SIZE-RELATED VARIATION IN THE SENSITIVITY OF THE MUSSEL, MYTILUS-EDULIS, TO COPPER

Juvenile mussels (Mytilus edulis, Mollusca: Bivalvia) were subjected t o a simple assay to investigate the pattern and timing of the shift fr om high copper resistance of the veliger larva to the lower resistance of the adult. The level of resistance found in veligers persists in m ussels of 1 mm shell length (400 ppb Cu; LT(50) 12.5 d) while the lowe r adult level of resistance is reached at a shell length of 5 mm (400 ppb Cu; LT(50) 2.8-5.3 d). Resistance declines gradually, being signif icantly correlated with shell length (P<0.02) such that size differenc es explain 88% of the variation in copper resistance among juvenile mu ssels.