Ecotoxicological Effects in Gilthead Seabream (Sparus aurata) Exposed to Environmentally Realistic Concentrations of Nickel Nanoparticles  ^†

Metalic nanoparticles (NPs) are emerging microcontaminants that have had, in recent years, increasing use in various sectors of the economy and society. Consequently, there is an urgent need to understand the environmental health consequences of the entry of these contaminants into the aquatic compartment. The objective of this study was to evaluate the ecotoxicological effects resulting from chronic exposure (28 days) to nickel NPs (Ni-NPs) at environmentally realistic concentrations (0.05 mg/L; 0.5 mg/L 5 mg/L), including a negative control (0.00 mg/L), in gills and liver of Sparus aurata. Antioxidant defense (Catalase, CAT), phase II metabolic detoxification (Glutathione S-Transferases, GSTs) enzymes, and lipid peroxidation (thiobarbituric acid reactive species, TBARS) were evaluated. Although the data showed that gills did not show significant differences in GST and CAT activities among the experimental goups, the group exposed to the highest dose (5 mg/L) showed a higher concentration of TBARS compared to the control. Regarding the liver, significant inhibition of catalase was observed for the different groups exposed to different concentrations of Ni-NPs. The assays performed suggest that the nanoparticles could promote biochemical alterations in the livers and gills of the exposed individuals, but more biomarkers of oxidative stress are needed to reveal the mechanistic pathways of Ni-NPs.