Evaluation of a chronic exposure to nanoplastics in goldfish (Carassius auratus): Analytical validation of automated assays for the measurement of biochemical markers

Abstract

The bulk of plastic pollution is mainly composed of small fragments, micro- and nanoplastics (NPs). Although many studies are currently published on NPs, research on the effects of NPs in fish after a chronic exposure is still scarce. The present study aimed to validate a series of automated assays to be used in the monitoring of fish challenged with a chronic exposure to NPs, using Carassius auratus (goldfish) as model species. For this purpose, adult C. auratus were exposed to 100 µg/L polystyrene (PS)-NPs for a 30-day period. Total oxidative status (TOS), total antioxidant capacity (TAC), esterase activity (EA) and adenosine deaminase activity (ADA) were measured in the gills, brain and muscle of fish. In addition, acetylcholinesterase activity (AChE) and creatinine kinase (CK) were measured in the muscle. All biomarkers were successfully validated in goldfish tissues and consequently used to assess the effects of NPs following a chronic exposure. Results showed that EA and TAC significantly increased in gills, while EA decreased significantly in the brain, and no effects were observed in any of these parameters in muscle. These results indicate that both immune and antioxidant responses were triggered by NPs in gills, but not in the brain nor muscle. This suggests that gills may be a primary target for NPs, potentially leading to a cascading effect on gas exchange, or osmo- and ionic regulation that should be further investigated.