The Effect Of Boat Noise On The Hearing Threshold Of The Acipenser Dabryanus Dumeril

The Yangtze River sturgeon(Acipenser dabryanus Dumeril),also known as Darden’s sturgeon,is one of the endangered species in China.Due to the influence of many human activities such as water conservancy projects,shipping,docks and fishing,the migration,feeding and natural reproduction of the Yangtze River sturgeon have been seriously disturbed in recent decades,and the natural population size of the Yangtze River sturgeon has declined sharply,even the natural reproduction stopped in2000.As the golden water-way in China,the busy shipping,water conservancy project construction,such as those caused the Yangtze river suffered the underwater noise pollution seriously,this is bound to cause adverse effect on the Yangtze river sturgeon,the existence of noise pollution on the influence degree of the Yangtze river sturgeon is unclear,so it’s necessary to know the Yangtze river sturgeon auditory threshold,records of underwater noise intensity in the Yangtze river.The study on the impact of these noises on the Yangtze River sturgeon will provide data support for the evaluation of the potential impact of underwater noise on rare freshwater fish such as the Yangtze River sturgeon.At the same time,hearing is also an important survival skill for fish,and the study of hearing threshold has important guiding significance for the understanding of the wild survival ability and species conservation of Yangtze River sturgeon.1.The hydrophone was used to record the intensity of ship noise in the Yangtze River where the sturgeon moved across the river,Arc GIS Map was used to show the distribution of noise in the river section.The results found that in the river section where the sturgeon moves,noise is negatively correlated with the distribution of fishery resources.In areas such as dams,wharfs,and ports where there is more ship noise,there are fewer fishery resources,while in areas with less ship noise.Fishery resources are relatively large,and ships have a greater impact on fish,which is bound to have an impact on the Yangtze River sturgeon in the reserve.2.Auditory Evoked Potential(ABR)techniques were used to test hearing threshold of the Yangtze sturgeons.The short pure tone evoked potentials of 20 sturgeons were recorded by electrode connection.The results showed that under the maximum volume intensity of the system,the Yangtze River sturgeon’s listening frequency range was 100-500 Hz,and the sturgeon had a high sensitivity to the sound of 200-300 Hz.The best sensitive listening frequency was 300 Hz,and the hearing threshold was about 133±0.5 d B.With the decrease of sound intensity,the auditory brainstem response waveform of the sturgeon also changed,the amplitude decreased and the latency increased.An audiogram of auditory brainstem response of 20 sturgeons was obtained by averaging the thresholds of 20 sturgeons.The results showed that the auditory chart of the sturgeons was not typical "U" shape,but changed with the frequency,which might be related to the hearing weakness of the sturgeons.The study of the auditory threshold of the Yangtze River sturgeon is of great significance to the conservation of the species,and also provides data support for the evaluation of the impact of noise on the sturgeon.3.Used the recorded ship noise in the field and the playback of a single noise stimulus in the laboratory background,the impact of ship noise exposure on the auditory threshold of the Yangtze River sturgeon and its recovery were studied.The Yangtze River sturgeon was exposed to ship noise for 1/2/4/8 h.Immediately after the exposure,the ABR method was used to determine the hearing threshold of the Yangtze River sturgeon and compared with the control group(not exposed to noise).In the 1 h-4 h exposure group,the auditory threshold of the 15 test Yangtze sturgeons did not change significantly compared with the control group.Even with the longer 8-hour stimulation,no changes were found in the auditory threshold of the Yangtze sturgeon..It is speculated that the Yangtze River sturgeon may be a hearinginsensitive fish.After being stimulated by ship noise,the hearing threshold cannot be changed in a short time.Short-term ship noise stimulation will not cause the auditory threshold shift of the Yangtze River sturgeon.Whether these threshold shifts cause damage to the auditory structure of the Yangtze River sturgeon and the cause of the threshold shift need to be further explored.