The effects of noise exposure on auditory sensitivity of fishes [abstract]

Amy R. Scholik and Hong Y. Yan (2002). The effects of noise exposure on auditory sensitivity of fishes [abstract]. Bioacoustics, Volume 13 (2): 186 -187

The underwater acoustic environment is inherently loud as a result of ambient sounds. In addition, there is an increasing amount of sound from anthropogenic sources, which produce noise within the hearing range of most fish (less than 1.0 kHz). For fish, the auditory system is one of the most important sensory systems because it provides information about ambient sounds, prey items, predators and potential mates. Since a fish's ability to accurately interpret its acoustic environment is essential for its survival, it is important to understand how noise affects sound perception ability of fish. This study examines the question: does noise exposure affect auditory sensitivity differently in hearing specialists (fish with coupling devices between the gasbladder or ancillary structures and inner ear, enhancing overall hearing with wider frequency range and lower threshold) and hearing generalists (fish without coupling devices, with narrow frequency range and higher threshold)? For this study, a hearing specialist species, the fathead minnow Pimephales promelas, and a hearing generalist species, the bluegill sunfish Lepomis macrochirus, were used to examine: (1) the immediate effects on auditory threshold of white noise exposure at various exposure durations (1-24 h at 0.3-4.0 kHz, 142 dB re: 1µPa); and (2) recovery time after noise exposure (1-14 days). Audiograms for noise-exposed fish were measured using the auditory brainstem response protocol, which records acoustically evoked brainwaves, and compared to control fish (no noise exposure). The results for specialists showed that their best hearing frequency range (0.8-2.0 kHz) was affected significantly more than other frequencies. In addition, recovery of hearing ability after noise exposure was found to be both frequency- and exposure-dependent. The results for hearing generalist fish will be presented and discussed (work supported by the Kentucky Academy of Science, National Organization for Hearing Research, NIMH-58198, Institute of Museum and Library Service-LL90187).