Effects of low-frequency underwater sound on hair cells of the inner ear and lateral line of the teleost fish <i>Astronotus</i> <i>ocellatus</i>

211

136

SUMMARY Underwater noise pollution is an increasing environmental problem which might affect communication, behaviour, fitness and consequently species'survival. The most common anthropogenic noises in aquatic habitats derive from shipping. In the present study we investigated the implications of noise pollution from a ship on the sound detectability, namely of conspecific vocalizations in the Lusitanian toadfish, Halobatrachus didactylus. Ambient and ferry-boat noises were recorded in the Tagus River estuary(Portugal), as well as toadfish sounds, and their sound pressure levels determined. Hearing sensitivities were measured under quiet lab conditions and in the presence of these masking noises at levels encountered in the field,using the auditory evoked potentials (AEP) recording technique. The Lusitanian toadfish is a hearing generalist, with best hearing sensitivity at low frequencies between 50 and 200 Hz (below 100 dB re. 1 μPa). Under ambient noise conditions, hearing was only slightly masked at lower frequencies. In the presence of ship noise, auditory thresholds increased considerably, by up to 36 dB, at most frequencies tested. This is mainly because the main energies of ferry-boat noise were within the most sensitive hearing range of this species. Comparisons between masked audiograms and sound spectra of the toadfish's mating and agonistic vocalizations revealed that ship noise decreased the ability to detect conspecific acoustic signals. This study provides the first evidence that fishes' auditory sensitivity can be impaired by ship noise and that acoustic communication, which is essential during agonistic encounters and mate attraction, might be restricted in coastal environments altered by human activity.

Section: Introductionmentioning

confidence: 99%

Effects of ship noise on the detectability of communication signals in the Lusitanian toadfish

Vasconcelos

Amorim²,

Ladich

2007

211

136

“…Even louder sounds, or longer exposure to somewhat quieter sounds, produce damage to the sensory cells of fish ears, as evidenced in the few fish species that have been studied, and this may lead to permanent loss of hearing (i.e. permanent threshold shifts; Enger, 1981;Hastings et al, 1996;McCauley et al, 2003). In addition to causing inner ear damage, high levels of background sound may create physiological and behavioral stress responses in fishes similar to those found in mammals (Smith et al, 2004).…”

mentioning

confidence: 99%

Acoustical stress and hearing sensitivity in fishes: does the linear threshold shift hypothesis hold water?

Smith

Kane

Popper

2004

Self Cite

105

SUMMARY Mammals exposed to loud aerial sounds exhibit temporary threshold shifts(TTS) that are linearly related to increases of sound pressure above baseline hearing levels. It was unknown if this relationship held true for aquatic ectotherms such as fishes. To test this linear threshold shift hypothesis(LINTS) in fishes, we examined the effects of increased ambient sound on hearing of two species differing in hearing capabilities: goldfish(Carassius auratus; a hearing specialist) and tilapia(Oreochromis niloticus; a hearing generalist). Fish were exposed to 1–28 days of either quiet (110 dB re 1 μPa) or continuous white noise. First, we examined the effect of noise sound pressure level (SPL; 130,140, 160 or 170 dB re 1 μPa) on goldfish hearing thresholds after 24 h of noise exposure. Second, in a long-term experiment using 170 dB re 1 μPa white noise, we continuously exposed goldfish and tilapia for either 7 or 21–28 days. In both experiments, we measured alterations in hearing capabilities (using auditory brainstem responses) of noise-exposed fish. While tilapia exposed to noise for 28 days showed little or no hearing loss,goldfish exhibited considerable threshold shifts that reached an asymptote of up to 25 dB after only 24 h of exposure. There was a positive linear relationship between noise-induced TTS and the sound pressure difference between the noise and the baseline hearing thresholds in goldfish but not in tilapia. A similar relationship was found for published noise-induced threshold shifts in birds and mammals, but the slope of the linear relationship was greater in these groups than for fish. The linear threshold shift relationship provides insights into differential susceptibility of hearing specialist and generalist fishes to noise-induced hearing loss for a given SPL and provides a framework for future research on noise-induced threshold shifts in fishes and other animals.

“…It is known that intense sounds can cause temporary hearing threshold shifts (Popper and Clark, 1976;Scholik and Yan, 2001) and damage to the sensory cells of the ears of the few fish species that have been studied (Enger, 1981;Hastings et al, 1996;McCauley et al, 2003). Besides damage to the inner ear, high levels of background noise may also create physiological and behavioral stress responses in fishes similar to those found in mammals (Welch and Welch, 1970).…”

mentioning

confidence: 99%

Noise-induced stress response and hearing loss in goldfish (Carassius auratus)

Smith

Kane

Popper

2004

Self Cite

256

207

Sound is an important means of communication in aquatic environments because it can be propagated rapidly (five times faster than in air) over great distances and it is not attenuated as quickly as other signals such as light or chemicals (Hawkins and Myrberg, 1983). Thus, it is not surprising that fishes and marine mammals make considerable use of sound for communication, for detection of predators and prey and for learning about their environment (Au and Nachtigall, 1997;Edds-Walton, 1997;Zelick et al., 1999;Fay and Popper, 2000).Within the past decade, there has developed an increased awareness that underwater anthropogenic (human-generated) sounds may be detrimental to marine organisms by masking the detection of biologically relevant signals and/or even damaging the exposed animals (NRC, 2000(NRC, , 2003. These sounds may be associated with shipping, dredging, drilling, seismic surveys, sonar, recreational boating and many other human-made sources. As a result of these human-generated sounds, ambient noise levels in the ocean are thought to be growing (NRC, 2003). Early estimates by Ross (1993) suggest a 10·dB increase from 1950 to 1975 alone or more than a doubling in noise level. This is likely to have risen further with increases in shipping and uses of other acoustic sources in parts of the oceans (NRC, 2003). Indeed, recent forecasts by the National Oceanographic and Atmospheric Administration's Marine Transportation System indicate that foreign oceanborne trade is expected to double by the year 2020 (US Department of Transportation, 1999), and this could result in even greater ocean noise levels in shipping lanes unless there are dramatic changes in ship acoustics.Substantial exposure of fish to acoustical stress is also found in many aquaculture facilities (Bart et al., 2001) that are important sources of food, ornamental species and stock enhancement of wild populations. While considerable effort has been made to optimize growth of aquaculture species by manipulating many environmental parameters such as temperature, food quality, photoperiod, water chemistry and stock density, little or no concern has been directed to determining the appropriate acoustic environment for optimal growth and development. Rearing conditions in aquaculture tanks can produce sound levels within the frequency range of fish hearing that are 20-50·dB higher than in natural habitats (Bart et al., 2001). The few studies that have examined the Fishes are often exposed to environmental sounds such as those associated with shipping, seismic experiments, sonar and/or aquaculture pump systems. While efforts have been made to document the effects of such anthropogenic (human-generated) sounds on marine mammals, the effects of excess noise on fishes are poorly understood. We examined the short-and long-term effects of increased ambient sound on the stress and hearing of goldfish (Carassius auratus; a hearing specialist). We reared fish under either quiet (110-125·dB re 1·µPa) or noisy (white noise, 160-170·dB re 1·µPa) conditions a...