Bioaccumulation of cadmium in the ascidian Styela clava (Herdman 1881)

Abstract

The processes of bioaccumulation and elimination of cadmium by tissues ofStyela clava (Herdman 1881) were investigated based on a semi-static two-compartment model. The kinetic parameters (accumulation rate constant k₁, elimination rate constant k₂, bioconcentration factor BCF, biological half-life t_1/2 and maximum equilibrium concentration C_Amax) were obtained by non-linear regression. The results showed that S. clava accumulates cadmium from its aquatic environment. BCF decreased with increasing metal concentration in the water, and when the accumulation achieved balance, C_Amax correlated positively with metal concentrations in the water. Concentrations of cadmium in different tissues of S. clava were: gonad > digestive gland ≈ other parts > tunic. The t_1/2 values for cadmium were 15.54–50.40 days in the accumulation process and 11.53–24.55 days in the elimination phase. The high rate of accumulation and elimination of cadmium from the body reveals the potential of the organism to be used as a biomonitor of short-term cadmium fluctuation in marine systems.

Keywords: accumulation;, cadmium; elimination; kinetics; Styela clava

African Journal of Marine Science 2009, 31(3): 289–295