Uptake, depuration and effect of cadmium on the green mussel Perna viridis (L. 1758) (Mollusca: Bivalvia)

Abstract

We evaluated the effect of a sublethal concentration of cadmium (0.04 µg Cd L^–1) on the physiological condition of the juvenile green mussel Perna viridis (22.3 ± 2.33 mm shell height), collected in Guayacán, Sucre State, Venezuela. The mussels were exposed to the sublethal concentration for 7 days, and were then depurated during 52 days simultaneously in the laboratory and in the field in plastic baskets suspended from a long line. In both conditions, the concentration of cadium was measured and different physiological indices were determined: oxygen consumption, ammonia excretion, total protein content in tissues, RNA/DNA ratio, and height and mass of the shell and tissues. No significant differences in the physiological indices were obtained during the depuration process in the laboratory but, in general, all the indices tested increased during depuration in the field. The RNA/DNA index showed great variability, proving to be unsuitable to evaluate the toxic effect of cadmium; however, total protein content, shell and tissue height and mass and, particularly, oxygen consumption and ammonia excretion rate proved to be suitable to evaluate the physiological condition of mussels exposed to subletal concentrations of xenobiotics.