Zn II accumulation in the soft tissue and shell of abalone Haliotis diÕersicolor supertexta via the alga Gracilaria tenuistipitata var. liui and the ambient water

This investigation analyzed the Zn-bioaccumulation kinetics in the abalone Haliotis diÕersicolor supertexta and in the red alga Gracilaria tenuistipitata var. liui for assessing bioconcentration and biomagnification in an aquacultural system. Laboratory exposure experiments estimated Ž . uptake and depuration rate constants i.e., k and k , respectively of H. diÕersicolor supertexta 1 2 Ž . via nondietary and dietary processes. Bioconcentration factor BCF and biomagnification factor Ž . BMF of H. diÕersicolor supertexta as well as BCF of G. tenuistipitata var. liui were determined. A simple first-order one-compartment model fitted the uptake and depuration characteristics of Zn-bioaccumulation and successfully determined k and k . The resulting values 1 2 of k and k of H. diÕersicolor supertexta were 101.4 ml g d and 0.611 d, respectively, 1 2 when the abalone were exposed to 1 mg ml Zn seawater without the presence of G. tenuistipitata var. liui. When the abalone were fed with the algae, k and k values were 1 2 estimated to be 114.5 g g d and 0.636 d, respectively. BCF values for the alga and abalone were determined to be 170 and 180, respectively; and the BMF value was 1.06 for the abalone. Both field and laboratory data show that BMF values for Zn were about 1. Further more, the abalone in the tank without algae absorbed the same quantity of Zn as the abalone in the tank with alga. From these two findings we conclude that Zn in the abalone comes from the ambient water and not from the algae. q 1999 Elsevier Science B.V. All rights reserved.