A Primary Study Of Anthropogenic Noise And It’s Effrcts On Marine Fishes

In order to reduce carbon dioxide emissions and stop global warming, as a kind of clean energy, the use of wind power gains increasing attention. China’s offshore wind power energy industry develops rapidly in recent years, however, during the life cycle of a offshore wind farm it will continue to release noise into the ocean in almost thirty years and causes noise pollution. The underwater noise from human activities is an environmental issue that has attracted much concern in the last few years, but there is few study of this field in our country,so it is very necessary for us to study the characteristic of single wind turbine and cumulative effect of multiple wind turbines. We collected the underwater noise data in Shanghai Donghai bridge offshore wind farm and studied the characteristic of single wind turbine, we also compared the sound pressure level inside and outside the wind farm and compared different methods during sound collection.The results show that the noise of offshore wind turbine has the characteristics of low frequency and low sound pressure level, it’s main frequency is within 400 Hz, and sound pressure level is between 81~99 d B. The main frequency of wind turbine B1(3 MW)are 60 Hz, 119 Hz, 235 Hz, 351 Hz,sound pressure level is about 89 d B; The main frequency of wind turbine A2(3 MW)are 62 Hz、124 Hz、238 Hz、325 Hz,sound pressure level is about 81 d B;The main frequency of wind turbine F1(3.6 MW)are 62 Hz、139 Hz、186 Hz、359 Hz,sound pressure level is about 99 d B;The main frequency of wind turbine F2(5 MW)is 69 Hz, sound pressure level is about 90 d B。In the range between 15~148 meters, the sound pressure level of single wind turbine decreased with increasing distance, but in 148 meters away there is no correlation between sound pressure level and distance. The results of underwater noise from different depth show that the frequency spectrums of noises from different depth are almost the same when the tidal flow velocity is slow, but when the tidal flow velocity speed up, some frequency component shift and lost. The study of sound pressure level of inside and outside the wind farm show that the sound pressure level inside the wind farm is lower than the outside, this may caused by the change of sea condition during sound collection. The results above show that the measurement of underwater noise from offshore wind farm is highly susceptible to interference such as the change of sea condition and we need a more strict condition if we want to have an accurate measurement of offshore wind turbine noise than the measurement of other high sound pressure level noise. Our study also shows that the two different methods we use to collect underwater noise are both available.The underwater noise caused by human activities such as offshore wind farm may affect the sound communication between fishes. False kelpfish(Sebasticus marmoratus)is a typical offshore reef fish and a important commercial fish,it can make a sound through sounding muscle during reproductive period or non-reproductive period and communicate between different individuals. We here use the method of Auditory Evoked Potential to study the hearing threshold of S.marmoratus. The auditory evoked potentials of 10 S.marmoratus were recorded using two electrodes to determine the hearing threshold of tone bursts from 80 to 1500 Hz. The results show that S.marmoratus. is sensitive to sound signals of low frequency and it’s hearing threshold is 72 to 79 d B. the best hearing of S.marmoratus is between 80 to 200 Hz, and the lowest threshold was 72 d B at 80 Hz. As the sound frequency increase, the auditory sensitivity of S.marmoratus decrease, and it has a poor sensitivity to the sound frequency above 500 Hz, and it’s hearing threshold is above 90 d B. Hearing threshold values from 10 individuals were averaged to form the audiogram of S.marmoratus. The audiogram is liner increase and shows S.marmoratus’ s hearing threshold increase with the increase of sound frequency increase.Combine the above results we think that the underwater noise caused by human activities such as offshore wind farm may affect the sound communication between fishes, but we need further behavior experiments to know whether this kind of noise will affect the behavior of marine organism. The noise protection and environment assessment of further offshore wind farm and behavioral experiment and noise exposure on marine life could be based on our data.