Study of toxicity and bioaccumulation of copper in the silver sea bream Sparus sarba

Abstract

The toxicity and bioaccumulation of copper were studied in fingerlings (mean body weight = 9.4±2.1 g) and subadults (mean body weight = 85.5±27.1 g) of the silver sea bream Sparus sarba. Test fish were obtained from local fish culture sites. Static tests over 96 h showed that subadults were not more tolerant to copper than the much smaller fingerlings. The 24-h, 48-h, 72-h, and 96-h LC50 for fingerlings were 2.01 mg Cu L −1, 1.28 mg Cu L −1, 1.17 mg Cu L −1, and 1.03 mg Cu L −1, respectively. The values for subadults were 2.36 mg Cu L −1, 1.52 mg Cu L −1, 1.34 mg Cu L −1, and 1.24 mg Cu L −1, respectively. Copper concentrations corresponding to 13%, 25%, and 40% of the 96-h LC50 value were used to study the effects of copper exposure on the growth rate of S. sarba in 30-d bioassays. The growth rate of fingerlings was higher than that of subadults by approximately a hundred-fold. For both fingerlings and subadults, reduced growth was observed at 0.15 mg Cu L −1 (∼40% of the 96-h LC50 value). Growth appeared to be a more sensitive endpoint for toxicity tests than mortality. Fish exposed to copper for 30 d contained more copper than control animals. The highest copper concentrations for both fingerlings and subadults were found in the intestine. The order of copper concentration was intestine > liver > gonad > gills, skin and muscle.