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

Abstract

The processes of bioaccumulation and elimination of cadmium by tissues of Styela clava (Herdman 1881) were investigated based on a semi-static two-compartment model. The kinetic parameters (accumulation rate constant k ₁, elimination rate constant k ₂, 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.