间歇性水下声音暴露后水生东部锦龟（Chrysemys picta picta）的噪声诱导暂时性阈移

文献信息

中文摘要

背景： 水生龟在暴露于连续宽带和窄带声音后可能发生水下听力损失，即暂时性阈移（TTSs）；一个关键问题是龟耳如何对间歇性声源作出反应。方法：我们将三只东部锦龟（Chrysemys pica pica）暴露于20分钟水下400 Hz 1/6倍频程窄带噪声，采用4种占空比（25-75%间歇；100%连续）和两种暴露幅度[累积声暴露级（SELcum）：156-172 dB re 1 μPa2s]。结果：在570 Hz进行的水下听觉诱发电位测量显示显著阈移，范围为6.4-27.4 dB，与连续暴露相比，间歇暴露后的TTS较低。尽管龟在所有测试占空比下均出现TTS，但间歇暴露内的恢复间隔似乎限制了TTS增长，这与在哺乳动物中观察到的情况相似。间歇噪声的阈移低于相同SELcum下100%占空比暴露所观察和预测的阈移，提示SELcum可能高估水生龟的TTS。与25%和50%占空比暴露相比，75%和100%占空比暴露后恢复速率更快，可能是因为诱导的TTS更大。结论：我们说明所观察到的阈移可能对生物学相关声音的检测距离产生显著影响，突显了对这一受威胁类群进行噪声管理的重要性。

英文摘要

Aquatic turtles can incur underwater hearing loss-or temporary thresholds shifts (TTSs)-upon exposure to continuous broadband and narrowband sound; a key question is how the turtle ear responds to intermittent sound sources. We exposed three Eastern painted turtles (Chrysemys pica pica) to 20 min of underwater 400 Hz 1/6-octave narrowband noise at 4 duty cycles (25-75% intermittent; 100% continuous) and two exposure amplitudes [cumulative sound exposure levels (SELcum): 156-172 dB re 1 μPa2s]. Underwater auditory evoked potential measurements at 570 Hz demonstrated significant shifts ranging 6.4-27.4 dB, with lower TTS after intermittent exposures, compared to continuous. Although turtles experienced TTS at all duty cycles tested, recovery intervals within the intermittent exposures appeared to limit TTS growth, as observed in mammals. Thresholds shifts for intermittent noise were lower than shifts observed and predicted for 100% duty cycle exposures of the same SELcum, suggesting SELcum may overestimate TTS in aquatic turtles. Faster recovery rates occurred after 75% and 100% duty cycle exposures, compared to 25% and 50%, likely because of the greater TTS induced. We illustrate observed shifts may have significant impacts on detection distances of biologically relevant sounds, highlighting the importance of noise management for this threatened taxon.