A parsimonious AUC-based biokinetic method to estimate relative bioavailable zinc to abalone Haliotis diversicolor supertexta

Abstract

We developed a mechanistic model based on the pharmacological area-under-curve (AUC) concept associated with a biokinetic rate model to predict relative bioavailable zinc (Zn) to abalone Haliotis diversicolor supertexta. We conducted a laboratory 14-day exposure experiment to obtain biokinetic parameters for soft tissue and shell of abalone and their food source, red alga Gracilaria tenuistipitata var. liui. The physiological parameters in terms of growth rate constants for abalone and algae were derived from literature. The present AUC-based model demonstrates that depuration rate constants and growth rate constants of abalone and algae are the critical parameters in predicting relative bioavailable Zn to abalone. During uptake phase of the exposure experiment, estimated relative bioavailable Zn to soft tissue and shell of H. diversicolor supertexta were 71.04±9.71% (mean±standard deviation) and 68.44±8.29%, respectively. Sensitivity analysis indicates that relative bioavailable Zn to abalone is greatly affected by growth rate and depuration rate constants of abalone and is less dependent on algae growth rate. We also applied a Monte Carlo approach to estimate the impact of parameter uncertainty on relative bioavailable Zn predictions. Our results suggest that the probabilistic approach allows a range of possible outcomes and their likelihood; it better informs both aquacultural risk assessors and risk managers. Our study suggests that we have to take into account both biokinetic and physiological processes in predicting the relative bioavailable metals to aquatic animals.