Relative contributions of food and water in the accumulation of zinc by two species of marine fish

A model food chain, utilizing ⁶⁵Zn-labeled and nonlabeled food organisms, was used to measure the relative contributions of food and water to Zn accumulation by Gambusia affinis and Leiostomus xanthurus. Chlamydomonas sp. was fed to Artemia sp. which in turn was fed to G. affinis and L. xanthurus. A trace metal-chelate buffer system was used to maintain a stable free Zn ion activity (10^-8.5 mol l^-1) in the experimental seawater. Food represented 78 to 82% of total accumulation of ⁶⁵Zn by the fish. Thus, food cannot be ignored in assessing the accumulation and toxicity of trace metals.