Noise-induced hearing loss in two otophysine fishes and effects on acoustic communication [abstract]

S. Amoser and F. Ladich (2002). Noise-induced hearing loss in two otophysine fishes and effects on acoustic communication [abstract]. Bioacoustics, Volume 13 (2): 204

There is growing concern that aquatic vertebrates may be affected by the increasing noise of anthropogenic origin in their environment. Several studies have been conducted on the effects of noise on marine mammals, but only a few studies have dealt with fish. The aim of the present study is to measure and compare the immediate effects of intense noise exposure (160 dB re 1 µPa for 12 and 24 hours) on two otophysine fish species, the non-vocal cyprinid Carassius auratus and the catfish Pimelodus pictus, which produces low-frequency drumming and high-pitched stridulatory-sounds. The second aim of this study was to determine the effects of noise on the ability of P. pictus to communicate acoustically. Hearing sensitivity was determined utilising the auditory evoked potential (AEP) recording technique. Measurements were performed prior and directly after noise exposure as well as after several days of recovery. Threshold shifts immediately after noise exposure ranged from 13-22 dB in C. auratus and from 7-34 dB in P. pictus. In both species the greatest hearing loss occurred at their most sensitive frequencies (C. auratus: 500 - 1000 Hz; P. pictus: 500-4000 Hz). Sound energies in the pimeloid catfish were maximally 10 dB above hearing curves immediately after noise exposure. Differences in recovery were observed between species. Carassius auratus recovered completely after 3 days, whereas in Pimelodus pictus reduced auditory sensitivity of up to 15 dB was still observed after 3 days. Our results showed that these two hearing specialists are differently affected by noise exposure and that the threshold shifts are more persistent in P. pictus. The hearing loss in the vocalising pimelodid catfish indicates that sound communication is impaired in noisy environments. This research was supported by the Austrian Science Fund (FWF No 12411 to F.L.).