Effects of copper in plasma, gills, liver and muscle of seabream (Sparus aurata, Linnaeus 1758) juveniles

In aquaculture, one of the major restrictions on production is due to disease. Copper sulphate is widely used as treatment, however, it is toxic and even fatal at high concentrations. Although toxilogical effects of copper in fish are well documented, the variability of results is large. In the present study, 121 seabream (Sparus aurata) juveniles of 130,97 ± 0,91 g (mean ± SD) were experimentally exposed to control group (0 mg Cu/L), treatment 1 (0,24 ± 0,04 mg Cu/L), treatment 2 (0,66 ± 0,12 mg Cu/L), treatment 3 (1,7 ± 0,09 mg Cu/L), during a period of 26 days followed with a recovery period to day 54. Principal results showed that while muscle and plasma Cu concentration did not vary among treatments, liver Cu concentration showed significant differences. In addition, diverse degrees of histopathological alterations were observed. This could be related to the treatment, and may be due to different physiological mechanism within the fish to mitigate copper effects.These mechanisms will define if a fish will or not adapt to different concentrations of copper. Fish held at the higher copper concentration died before the end of the experiment, proving that this concentration is fatal fo seabream juveniles in less than 8 days. Results point to copper, independently of the dose, as inducer of histopathological alterations. This study also suggests histological and histochemical improvement in seabream during recovery period. In summary, copper sulphate treatment may be a toxicological condition for seabream, which produce histological alterations and copper accumulation. Nevertheless, these changes could be restored with a recovery period.