Effects of Short Term Methylmercury Exposure on Growth and Development of the Large Yellow Croaker Embryos and Larvae

Due to the high toxicity in aquatic food chain, the toxic effects of methylmercury (MeHg) on organisms have caused widespread concerns, but little has been reported on its effects on marine fish. The acute and sub-lethal toxicities of MeHg chloride to an important aquaculture species in southeast coast of China-large yellow croaker (Pseudosciaena crocea) embryos and larvae were investigated in this study. Acute toxicity tests showed that the 48-h LC50 values of methylmercury to fish embryos and larvae were 28.39 (21.33-33.98) and 18.27 (11.33-29.29) mu g L-1, respectively. The 96-h LC50 value for larvae was 9.28 (4.41-14.49) mu g L-1, which indicated that fish larvae were more sensitive to MeHg than the embryos. On the other hand, MeHg exposure induced delayed hatching process, lower yolk absorption rate, higher morphological malformations at concentrations >= 1 mu g L-1, and caused higher larvae heart rate, lower survival and hatching success at concentrations >= 5, 10, and 20 mu g L-1, respectively. The results suggested that the hatching, survival and growth of the large yellow croaker during the early life stages may serve as sensitive biomarkers for marine MeHg pollution.