Effects of underwater noise on auditory sensitivity of a cyprinid fish Free

The ability of a fish to interpret acoustic information in its environment is essential for survival. Thus it is important to understand how underwater noise, from anthropogenic sources such as boats, affects fish hearing. In this study, the fathead minnow, Pimephales promelas, was used to examine the following: (1) the immediate effects of white‐noise exposure (300–4000 Hz, 142 dB re: 1 μPa) on auditory thresholds; (2) recovery time of hearing ability after exposure; and (3) the effects of noise exposure, from a small boat engine recorded in the field, on hearing thresholds. Audiograms were measured using the auditory brainstem response (ABR) protocol and compared to fathead minnows not exposed to noise. Immediately after exposure to white noise, five out of the eight frequencies tested showed a significantly higher threshold compared to the control fish. Recovery was found to depend on both duration of noise exposure and auditory frequency. Boat engine noise, peak frequency of 1292 Hz, also elevated thresholds in the fathead’s most sensitive hearing range (1000–2500 Hz). These results support the hypothesis that auditory thresholds can be altered by noise in the environment and provide evidence to show that these effects can be long term (>14 days). [Work supported by the Kentucky Academy of Science.]