The toxic effects of copper on larvae of the barnacle species Chthamalus challengeri

Abstract

With the increased use of copper (Cu)-based antifouling (AF) paints, copper has become a potential threat to marine organisms. Experiments were performed to investigate the effects of copper on larvae of the barnacle Chthamalus challengeri. These experiments attempted to identify a more sensitive index to monitor copper pollution in marine environments. The 24 h LC50 ranged from 156.07 μg/L (nauplius II) to 817.15 μg/L (cypris) and the no observed effect concentration (NOEC) ranged from 81.75 μg/L (nauplius II) to 571.04 μg/L (cypris). The cypris settlement rate declined significantly when copper concentrations ≥135 μg/L. No cypris was found in the copper concentration of 60 and 75 μg/L treatment groups stressed for 22 d. Nauplius II moulting was not affected by exposure to copper for 24 h; however, when extended to 48 h, the percent moulted in 75 μg/L treatment group was declined to 37.12%, which was significant lower (P <0.05) than that in the control group. The phototaxis of nauplius II decreased significantly when copper concentrations ≥45 μg/L. Despite an initial significant increase at copper concentrations of 30 μg/L, ammonia excretion rate decreased when copper concentrations ≥60 μg/L. These results suggested that: (1) nauplius II could not develop to the cypris when the copper concentration ≥60 μg/L; (2) cypris settlement is more susceptible to copper than cypris mortality rate; (3) nauplius II is the most sensitive larval stage; (4) nauplius II ammonia excretion rate is the most sensitive index to copper and might be as the indicator for copper pollution monitoring.