T7 AM Metals in the Environment: Dietary Concerns in Aquatic Systems
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 327-329

(CHE-1117-617110) Subcellular Cd distribution, accumulation and toxicity in predatory gastropod, Thais clavigera, fed different prey.

Cheung, MS ¹, Fok, EMW³, Ng, T², Yen, Y-F³, Wang, W-X², ¹ Atmospheric, Marine, Coastal Environment Program, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Knog, China³ Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China² Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China

ABSTRACT- Bioaccumulation and toxicity of Cd were investigated in a marine predatory whelk, Thais clavigera, after being fed with the rock oyster, Saccostrea glomerata, or the herbivorous snail, Monodonta labio, for up to 4 weeks. The oysters and snails had different Cd speciations and concentrations in their bodies given their different metal handling strategies, and were previously exposed to dissolved Cd for 2 weeks before being fed to the whelks. After 4 weeks of dietary exposure, the Cd body burdens in T. clavigera increased from 3.1 mg g-1 to 22.9-41.8 mg g-1 and to 22.7-24.1 mg g-1 when they were fed with oyster and snail prey, respectively. There was an increasing proportion of Cd distributed in the metallothionein-like protein and organelle fractions, whereas the relative distribution in the metal-rich granule decreased when the whelks were fed Cd-spiked prey. At the highest Cd dosage, more Cd was distributed in the metal-rich granule pool when the whelks were fed the oysters than when they were fed with the snails. Among all the biomarkers measured (metallothionein-MT induction, condition index, lipid peroxidation, energy content including carbohydrate, lipid and proteins), only the MT showed a significant difference from the control treatments and was the most sensitive biomarker for dietary Cd exposure. No toxicity was found in the whelks fed different Cd-exposed prey as revealed by various biomarkers at the different biological levels. Our results imply that metal speciation in prey can alter subcellular metal distribution in predators, and dietary Cd toxicity to the whelks was low even when the accumulated Cd body burdens were high.

Key words: Cd, dietary toxicity, trophic transfer, bioaccumulation