The effects of copper, cadmium and zinc on particle filtration and uptake of glycine in the Pacific oyster Crassostrea gigas

Abstract 1. The filtration rate (volume of water completely cleared of collodial carbon per unit time) by control oysters is 36.60 ml/g hr ± 7.68 (sd). 2. Filtration rates decrease with increasing concentrations of Cd 2+ and Zn 2+ . 3. In 8–16 mg/l Cu 2+ , filtration rates are significantly higher than the control, but in Cu 2+ concentrations above 32 mg/l, filtration rates are lower than controls. 4. Influx of 14 C-glycine is characterized by Michaelis-Menten kinetics with J max and K t values of 1.85 ± 0.097 μ mol/g hr and 33.7 ± 4.6 μ M respectively. 5. The uptake rate of glycine from 1 μM solution is 37.79 μmol/g hr. 6. In order of degree of inhibition of glycine uptake, Cu 2+ > Cd 2+ > Zn 2+ . 7. In 128 mg/l Cu 2+ , glycine uptake rate is reduced to 3.96 nmol/g hr or 10.5% of control. 8. The rate of glycine uptake by filter feeding bivalves is dependent on rate of water pumping rate. 9. The volume specific glycine transport (amount of glycine transported/unit volume of seawater completely cleared of colloidal carbon) by control oysters in 1 μM glycine concentrations is 1.03 μmol/l. 10. The volume specific glycine transport remains constant in increasing Zn 2+ concentrations, and declines in increasing Cu 2+ concentrations, suggesting differential effects of the metals on particle filtration and the epithelial amino acid carriers. 11. The apparent volume specific glycine transport increases to 2.14 μmol/l in 128 mg/l Cd 2+ . This volume specific transport greater than the glycine concentration in the medium suggests that there may be uptake of cadmium complexed glycine by the oysters.