| Summary: | 碩士 === 國立臺灣海洋大學 === 海洋生物研究所 === 106 === Short-term exposure of strong underwater noise may cause avoidance behaviour, temporary hearing loss or acute stress on fish. However, long-term physiological effects of continuously, but weak sound perturbation were not clear. To realize the impacts of operation noise of offshore wind power generator, the audiogram of the experiment animal, black porgy (Acanthopagrus schlegelii), was measured via auditory brainstem response (ABR). As well as, the fish were exposed to the simulated-wind farm noise, either strong noise condition (138 dB re 1 μPa/125.4 Hz; approx. nearby the wind farm) or weak noise condition (109 dB re 1 μPa/125.4 Hz; 10-100 m distant from the wind farm) for 24 hours, 1 week and 2 weeks to understand the possible chronic stress responses. The circulation cortisol levels and reactive oxygen species (ROS) levels were measured, and the responses of antioxidants were investigated by the hepatic mRNA levels of the gene encoding to Cu/Zn superoxide dismutase (Cu/Zn-sod), catalase (cat) and glutathione peroxidase (gpx).The ABR results showed that hearing thresholds of black porgy were lower than sound pressure levels of strong noise condition at the dominant frequency (125.4 Hz), but the hearing thresholds were similar to the sound pressure levels of weak noise condition at that frequency, which indicated that black porgy may able to hear the operation noise in short distance, but the sound level of the noise 10-100 m away may just reach their hearing sensitivity. Furthermore, although there was no significant different in the circulation cortisol levels, results suggested that long-term exposure of noise may cause black porgy chronic stress, in which the plasma ROS levels was significantly increasing after 2 weeks of strong noise exposure. Additionally, in the weak condition group, the plasma ROS levels was lower than control at week 1st, but higher than control at week 2nd; meanwhile, the hepatic cat gene expression was significantly lower, but the gpx gene expression was higher in the fish under strong noise condition. This study concluded that under the noise that close to the hearing threshold, black porgy may be able to keep the ROS levels stable by the regulations of genes regarding to antioxidant. However, when the fish exposed to the continuous noises that were far higher than the hearing threshold, the absent of such antioxidants response may result the accumulation of plasma ROS. Moreover, this study showed that the exposure of continuous offshore wind farm operation noise cause chronic stress on fish potentially, which included the response of antioxidants and ROS levels. Nevertheless, such effects occurred under very extremely condition, which may not be the case in the open ocean.
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