Effect of two different farming systems on the redox balance in gilthead sea bream Sparus aurata Linnaeus, 1758

The aim of the present study was to evaluate the redox balance in gilthead sea bream Sparus aurata Linnaeus, 1758 reared under two different farming systems (onshore tanks and offshore cage) to highlight how the different farming conditions can affect this oxidative stress (OS) index. For this purpose, forty healthy fish cultured in a Sicilian farm with different management (twenty taken from an onshore system and twenty from an offshore system) were sampled and subjected to blood collection. Successively, total oxidant status (TOS) and total antioxidant capacity (TAC) were measured in the obtained serum samples. Finally, oxidative stress index (OSI) was calculated as TOS/TAC ratio. In both farming systems physical and chemical characteristics of water were detected. Our results showed higher levels of TOS and OSI, and lower levels of TAC in fish held in onshore system respect to fish reared in offshore system. Moreover, linear regression analyses between TOS and TAC values showed different trends according to the different rearing technologies. This could confirm that changes in abiotic factors, such as temperature and dissolved oxygen concentration and, more generally, different rearing technologies may affect the redox balance in cultured gilthead sea bream, making it useful not only to evaluate the health status of fish but also indirectly to optimize husbandry practices.