Fish farming and anti-fouling paints: a potential source of Cu and Zn in farmed fish
The accumulation of copper and zinc, the basic components of anti-fouling paints, was examined in cultured sea bass Dicentrarchus labrax and sea bream Sparus aurata. Samplings were carried out at 4 eastern Mediterranean fish farms. Two of the farms used nets treated with anti-fouling paints, and 2 used untreated nets. At each farm samples of sediment and fish tissue (muscle, liver and gills) were analysed for heavy metal concentrations. The results showed that while total copper and zinc concentrations in sediments were quite similar in samples collected from the 4 farms, the extractable copper concentration in sediment from farms using anti-fouling treatment was 2 to 3 times higher than from those using untreated nets. Statistical analysis revealed no significant differences for either metal between sediment samples from farms using anti-fouling treatment and those which did not, except for extractable copper concentrations. However, analysis of the biological samples showed that copper concentrations in muscle tissue were lower in samples from farms using untreated nets, with the highest copper concentrations being observed in fish livers from farms using anti-fouling paints. General linear model results indicated significant differences between heavy metal concentrations in fish samples from farms using antifouling paints and those which did not. Furthermore, 1-way ANOVA indicated that these differences were confined to liver tissue for zinc, whereas significant differences for copper were seen in all tissues (except for gills of sea bream) for both species studied. These results indicate that the use of anti-fouling paints may be a potential source of metal accumulation in cultured fish.