| Chinese Sturgeon(Acipenser sinensis),is the national level to protect animals in China.However,In recent years,due to human activities,such as hydropower operation,waterway regulation,ship navigation,the wild population of Acipenser sinensis has decreased sharply.From 2017 to 2021,the natural reproduction of A.sinensis was interrupted,and the survival situation of its wild population was very serious,facing the risk of extinction.As the world’s “golden waterway”,the Yangtze River is increasingly polluted by underwater noise caused by busy shipping,which is bound to have a certain adverse impact on the habitat and reproduction of A.sinensis and other fishes.However,there is no relevant report on the specific impact of ship noise on A.sinensis.Therefore,by studying the hearing ability of A.sinensis,this paper analyzes the ship noise background in the waters of the important habitat of A.sinensis,and explores whether the noise has an impact on the hearing threshold of juvenile A.sinensis.It provides a basic reference for mastering the impact of water noise on wild A.sinensis and other fish,and plays an important role in the protection of important aquatic animals such as A.sinensis.1.Auditory Brainstem Response(ABR)was used to measure the auditory threshold of juvenile A.sinensis.The short pure tone auditory evoked potentials of 15 juvenile A.sinensis were recorded by inserting electrodes into the skin.The results showed that the hearing frequency range of juvenile A.sinensis was narrow,the sensitive frequency was in the range of 100 ～ 500 Hz,the most sensitive frequency was250 Hz,and the hearing threshold was 129.5 d B.The collected data at each frequency are analyzed to obtain the lowest threshold at each frequency.After statistical processing,the audiogram of juvenile A.sinensis.In the experimental environment,the audiogram of juvenile A.sinensis was similar to the “U” shape,which was similar to the hearing curve of spoon sturgeon and lake sturgeon.The listening frequency range was narrow and the threshold was high,so it belongs to hearing insensitive fish.2.Through analyzing and processing the ship noise recorded in Yichang A.sinensis nature reserve on the Yangtze River,the frequency band of ship noise with similar auditory threshold of juvenile A.sinensis was intercepted by Adobe audit CC software for playback,and the effects of ship noise stimulation in different time periods on the auditory threshold of juvenile A.sinensis were studied.Twenty-five juvenile A.sinensis were exposed to ship noise for 1,2,4,8 and 16 h.Immediately after the noise stimulation,the auditory threshold of the experimental fish was measured by ABR method,and compared with the control group(not stimulated by any noise).The results showed that the auditory threshold of juvenile A.sinensis did not change compared with the control group in 1h and 2h ship niose stimulation group;In the 4-h exposure group,the auditory threshold of juvenile A.sinensis began to change at the frequency of 200 Hz.The maximum change in the experimental group occurred at the frequency of 250 Hz,and the measured threshold was 131 d B(129.5 d B at 250 Hz in the control group);In the 8 h noise exposure group,the change of threshold was the most obvious.At the frequency of 250 Hz,the threshold increases by about 3.5 d B compared with the control group(133.5 d B at 250 Hz in the test group and 129.5 d B at 250 Hz in the control group);The threshold also changed in the 16 h noise exposure group,and there was no obvious upward trend compared with 4 h and 8 h stimulation group.Overall,the auditory threshold shift of juvenile A.sinensis was small after being stimulated by ship noise for different periods of time. |
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