PARENT SESSION

PT12 Metals and Bioaccumulation
Exhibit Hall
8:00 AM - Tuesday

(PT158) Influences of Zn exposure on the bioavailability of Cd and Zn to two marine fish.

ZHANG, Li¹, WANG, Wen-Xiong¹, ¹ Department of Biology, Hong Kong University of Science and Technology, Hong Kong, China

ABSTRACT- Zinc is an essential metal but a potential toxicant to aquatic organisms. The bioaccumulation of Zn by marine fish is not well studied. In this study, two juvenile marine species, Terapon theraps (grunt) and Acanthopagrus schlegell (seabream), were exposed to a series of Zn concentrations from either waterborne or dietary routes for 1 and 3 weeks. After exposure, the concentrations of Zn and metallothionein (MT) in the gills, viscera and remaining tissues were all enhanced in both fish species. Waterborne and dietary Zn exposure enhanced dissolved uptake rates and assimilation efficiency (AE) of Cd and Zn as well. The increases of dissolved uptake rate constants (k_u) of Cd and Zn were up to 2.8 and 2.2x, respectively in T. theraps, and 1.9 and 2.6x in A. schlegell. Enhancement of the AEs of Cd and Zn were however not significant in the two species. We further showed that there was a positive linear relationship between k_u or AE and the Zn or MT concentration in the fish. The results suggested that Zn exposure increased the potential of metal uptake from the waterborne route in these two marine fish. Any change in metal accumulation from the diet may be mainly determined by change in metal concentration in the prey organisms.

Key words: marine fish, Zn, bioavailability, bioaccumulation