Stress in rearing: Biochemical and growth impacts of acoustic exposure in juvenile Dicentrarchus labrax.

Acoustic pollution is an emerging concern in aquaculture, where continuous exposure to noise can affect the welfare of farmed fish. Juvenile fish may be more susceptible to acoustic disturbances during their growth phases, which could potentially affect their physiological responses. The European seabass (Dicentrarchus labrax) is an important species in aquaculture due to its economic value and widespread farming, making it a relevant model for studying the effects of acoustic pollution on farmed species. This study aimed to evaluate the short-term effects (30 min, 3 h, 24 h, and 7 days) of traffic noise exposure on the cellular responses of juvenile Dicentrarchus labrax, using whole-body analyses. Acoustic emissions were recorded from four different fishing vessels at distances between 10-15 m, with recordings played back randomly separated by 10 to 30-second intervals of silence between consecutive emissions. The biomarkers tested included heat shock protein 70 (HSP70), superoxide dismutase (SOD), glutathione peroxidase (GPx), adrenocorticotropic hormone (ACTH), cortisol, glucose, esterase, and alkaline phosphatase. The results revealed significant alterations in these parameters after just 30 min of exposure, with a tendency toward recovery after 7 days. Furthermore, a statistically significant reduction in growth rates was observed in exposed individuals. Although these findings may not apply to all species of farmed fish, they provide valuable insights into minimizing acoustic impacts and improving animal welfare in aquaculture environments.