Physiological stress response in Nile tilapia (Oreochromis niloticus) exposed to firework noise

In the present study, impacts of firework noise on physiological response and stress recovery were investigated in Nile tilapia (Oreochromis niloticus). Two treatment groups, one with firework noise exposure, and a control with no noise exposure at all was used in the study. After a disturbance challenge with firework noise for 2-hour playback, fish behavior in terms of opercula beats and pectoral wing flaps as physiological response were monitored for 96-hours via video image tracking, which was then consecutively repeated with 4-days intervals and 15 repetitions over a period of 60 days. Elevated fish respiration rates after noise exposure, peaked in 24 hours, and declining to initial levels after 72 hours, an indication of stress recovery. In the long-term challenge with multiple exposures to firework noise, fish showed no attunuation to firework noise and presented the same alarm reflex every time of noise exposure with 4-days intervals. It has been evidenced that fireworks noise influenced fish stress and welfare, hence the findings in this study may support ecology-based management of coastal developments. Further, these results raise the question of whether short-term investigations are sufficient for understanding anthropogenic disturbance on aquatic animals.