PCBs contamination in farmed European sea bass from different Italian rearing systems

The chemical composition and the level of twelve PCB congeners (IUPAC Nos. 18, 28, 31, 44, 52, 101, 118, 138, 149, 153, 180 and 194) were determined in 133 specimens of European sea bass (Dicentrarchus labrax), collected from four Italian aquaculture facilities: extensive valley, semi-intensive ponds, intensive concrete tanks and sea-cages. Fish muscle composition varied based on the rearing system (P< 0.001): moisture was higher and fat concentration was lower in fish from the extensive system in comparison to fish from intensive tanks; intermediate values were found in fish from semi-intensive ponds and sea-cages. Concentrations of the 12 measured PCBs (PCBtot) and of the seven indicator congeners (PCB7) (Nos. 28, 52, 101, 118, 138, 153 and 180), when expressed on fat weight, were lower in extensively-reared sea bass (112.0 and 74.6 ng/g fat, respectively) with respect to sea bass from the other systems (average values: 179.7 and 123.2 ng/g fat) (P< 0.001). When the values were expressed on fresh muscle weight, PCBtot and PCB7 were lower in extensively-reared sea bass (3.412 and 2.266 ng/g fw), intermediate in fish from semi-intensive ponds (15.398 and 10.632) and sea cages (13.123 and 8.882), and higher in specimens from the intensive tanks (18.176 and 12.440) (P< 0.001). PCB 153 was the most abundant in all of the rearing systems. Within farm, muscular fat content and slaughter weight were positively correlated (r = 0.79). PCB7 concentration expressed in ng/g fat and in ng/g fw was positively correlated with both fish slaughter weight (r = 0.71 and 0.73) and muscular fat concentration (r = 0.86 and 0.96).