Heavy metal indicator potential of the Asiatic clam (Corbicula fluminea) in artificial stream systems

The potential of the Asiatic clam, Corbicula fluminea, as a bioindicator of cadmium, copper, and zinc was studied during 28-day exposures in field artificial streams receiving river water on a once-through basis. Copper, at aquatic concentrations of 0.016 and 0.057 mg l^-1, showed the greatest degree of tissue uptake and had bioconcentration factors (BCF) of 22 571 and 17 720, respectively. A significant correlation (coefficient = 0.639) was observed between water concentration and tissue accumulation. Cadmium was intermediate relative to BCF (3 770 and 1 752 at aquatic exposures of 0.023 and 0.055 mg l^-1, respectively), and had a correlation coefficient of 0.758. Zinc had the lowest potential for concentration (631, 358, and 511 BCF at 0.218, 0.433, and 0.835 mg l^-1, respectively) with a correlation coefficient of 0.478. The rate of accumulation in Corbicula reached a maximum after 11 days for cadmium while a steady state condition for copper was not observed in 28 days. Zinc accumulation, like copper, showed a relative increase throughout the 28-day exposure period. Data from this study show that the Asiatic clam may be a reliable indicator of uptake for exposure to selected heavy metals.