Acute and Sublethal Effects of Ethylmercury Chloride on Chinese Rare Minnow (Gobiocypris rarus): Accumulation, Elimination, and Histological Changes

Ethylmercury (EtHg) has been widely observed in the environment due to anthropogenic contamination and/or environmental ethylation of inorganic mercury. Herein, the acute and sublethal effect of EtHg chloride on Chinese rare minnow (Gobiocypris rarus) as a fish model was studied. EtHg chloride showed an obvious toxicity to 4-month-old Chinese rare minnow (LC50 24.8 mu gL(-1) (as Hg) at 24h). Histological analysis revealed that acute EtHg exposure can induce necrosis, telangiectasis and exfoliation of epithelial cells in the gill, as well as edema, vacuoles, and pyknotic nuclei in hepatocytes. Sublethal dose exposure revealed a very high accumulation of EtHg in fish, which is subsequently metabolized to inorganic mercury and eliminated after depuration. A new mercury species, possibly diethylmercury, was also observed as the metabolite of EtHg in rare minnow. The present study provides useful information for assessing the risks of EtHg and understanding its bioaccumulation in aquatic organisms.