Evaluation of acute copper toxicity during early life stages of gilthead seabream, Sparus aurata

Abstract

In this study, the effects of exposure to copper (mortality and morphological alterations) on the early life stages of the gilthead seabream, Sparus aurata, were examined. Eggs/embryos and larvae were exposed to nominal concentrations of copper ranging from 0.0001 to 10 mg/L Cu (II) in the tests with eggs/embryos and 0.025 to 0.5 mg/L Cu (II) in the test with larvae. Duration of the assays was 48 hours for embryos and 96 hours for larvae. A high percentage of mortality was observed in embryos exposed to 0.1 mg/L (97.2%) and in larvae exposed to 0.5 mg/L (100%). The embryos proved the most sensitive to copper for the same duration of exposure. The acute toxicity expressed as LC50 48 hours was 0.054 (0.048–0.058) mg/L for embryos and 0.261 (0.182– 0.375) mg/L for larvae. Morphological alterations or abnormalities in embryos included irregular shapes of chorion, opacity and vitellus retraction/degeneration. In larvae we observed poor capacity to swim, trembling, myoskeletal defects, opacity and exophthalmia. Histopathological alterations are observed in S. aurata larvae. Mucous cells of the digestive tissue present a severe alteration with an increment of exudates. A great cellular disorganization in the renal tissue is observed. Results from this work indicate the high sensitivity of early life stages of Sparus aurata to copper (II) and the persistence of sublethal effects.