Mixed function oxidase activity and organochlorine levelks in farmed sharpnout seabream (Diplodus puntazzo) from two intensive aquaculture facilities

Abstract

Mixed function oxidase (MFO) activities and organochlorine levels were investigated in liver of farmed sharpsnout seabream bred in two intensive facilities, a sea farm and a land-based farm. The aim of this study is to investigate how different facility locations and breeding conditions might affect fish metabolic capabilities and accumulation of toxic chemicals in farmed sharpsnout seabream. The differences between breeding two or more fish species in the same cage or tank known as polyculture and monoculture (1 species) were also investigated. The results showed that both facility location (sea and land) as well as breeding systems (polyculture and monoculture) might be responsible for the differences observed in both MFO enzyme activity and organochlorine levels. Significantly higher activities of two metabolizing enzymes such as 7-ethoxyresorufin-O-deethylase (EROD) and benzo(a)pyrene monooxygenase (B(a)PMO) were in fact recorded in land-based farmed fish than in sea farmed ones, and much higher in those from polyculture than in monoculture (p<0.05). By contrast, the highest levels of dichlorodiphenyldichloroethilene (ppDDE) and polychlorinated biphenyls (PCBs as Aroclor 1260) were measured in sea-farmed fish, except for hexachlorobenzene (HCB), which gave higher levels in land-based farmed fishes. No significant differences were observed between monoculture and polyculture in p,pDDE and PCBs levels except for p,pDDE which was significantly higher in monoculture than in polyculture (p<0.05) in fish reared in tanks. Finally significantly higher HCB levels were measured in fish reared in monoculture in tanks (p<0.05) and in polyculture in cages (p<0.05). The low TEQ values obtained for PCB congeners at liver level indicated no concern for fish health.