Friedrich Ladich

A comparative study of hearing ability in fishes: the auditory brainstem response approach

Auditory brainstem response (ABR) techniques, an electrophysiological far-field recording method widely used in clinical evaluation of human hearing, were adapted for fishes to overcome the major limitations of traditional behavioral and electrophysiological methods (e.g., invasive surgery, lengthy training of fishes, etc.) used for fish hearing research. Responses to clicks and tone bursts of different frequencies and amplitudes were recorded with cutaneous electrodes. To evaluate the effectiveness of this method, the auditory sensitivity of a hearing specialist (goldfish, Carassius auratus) and a hearing generalist (oscar, Astronotus ocellatus) was investigated and compared to audiograms obtained through psychophysical methods. The ABRs could be obtained between 100 Hz and 2000 Hz (oscar), and up to 5000 Hz (goldfish). The ABR audiograms are similar to those obtained by behavioral methods in both species. The ABR audiogram of curarized (i.e., Flaxedil-treated) goldfish did not differ significantly from two previously published behavioral curves but was lower than that obtained from uncurarized fish. In the oscar, ABR audiometry resulted in lower thresholds and a larger bandwidth than observed in behavioral tests. Comparison between methods revealed the advantages of this technique: rapid evaluation of hearing in untrained fishes, and no limitations on repeated testing of animals.

Effects of ambient and boat noise on hearing and communication in three fish species living in a marine protected area (Miramare, Italy)

The WWF-Natural Marine Reserve of Miramare (Trieste, Italy) is located in a major industrial and vacation area in the Adriatic Sea. Consequently, noise emanating from boating and shipping is an inevitable factor for local fishes. This study investigates the effects of ambient and ship noise on representatives of three vocal fish families with different hearing abilities. Ambient and ship noise were recorded, their sound pressure levels measured and played back in the lab. Auditory sensitivity was determined in Chromis chromis, Sciaena umbra and Gobius cruentatus, utilizing the auditory evoked potential recording technique. Compared to lab conditions, hearing thresholds determined during ambient noise playbacks were barely masked. Contrary, the noise emanating from a cabin-cruiser substantially reduced auditory sensitivity relative to thresholds in ambient noise. This masking effect was most pronounced in the frequency range where acoustic communication takes place. Boat noise potentially affects acoustic communication in fishes inhabiting the reserve.

Parallel Evolution in Fish Hearing Organs

Fishes, as broadly defined to include agnathans (jawless fishes), cartilaginous fishes, and bony fishes, are the earliest vertebrates (Fig. 4.1). Because an inner ear is found in the fossil record of the most primitive jawless vertebrates (Forey and Janvier (1994), it is reasonable to assume that the ear, and possibly hearing, arose quite early in this group or was present in their ancestral chordates. Although there has been some suggestion that vertebrate inner-ear sensory hair cells may be derived from a statocyst-like system invertebrate mechanoreceptive cell, this is very much open to question (reviewed in Coffin et al., Chapter 3). More importantly for this chapter, it is highly likely that the vertebrate ear arose de novo in this group or perhaps in craniate ancestors (see van Bergeijk 1967 and Wever 1974 for a discussion of the origin of the vertebrate ear and Lewis and Fay, Chapter 2, for a discussion of the origin of hearing).

Agonistic behaviour and significance of sounds in vocalizing fish

Vocalization during agonistic behaviour is widespread in fishes and has been described in representatives of about 30 families. Many species utter sounds when disturbed or caught, probably to startle predators. During aggressive intraspecific encounters fishes mainly vocalize while attacking or fighting, and only rarely in defense situations or when fleeing. Acoustic signals are typically accompanied by visual displays which complicates analysis of sound function. Sounds are mostly short and composed of a series of low frequency pulses. Different types of agonistic acoustic signals as in Polypterus are rare. Males are often more vocal than females but in some species e.g. cottids and gouramis sexual differences in agonistic calls are small. Agonistic vocalizations may affect outcome of contests, defense of territories, and inhibit or increase aggression. Correlation between several sound characteristics and outcome of encounters in Trichopsis vittata indicates that sound parameters are used for assessing ...

Did Auditory Sensitivity and Vocalization Evolve Independently in Otophysan Fishes

Otophysine fishes have a series of bones, the Weberian ossicles, which acoustically couple the swimbladder to the inner ear. These fishes have evolved a diversity of sound-generating organs and acoustic signals, although some species, such as the goldfish, are not known to be vocal. Utilizing a recently developed auditory brainstem response (ABR)-recording technique, the auditory sensitivities of representatives of seven families from all four otophysine orders were investigated and compared to the spectral content of their vocalizations. All species examined detect tone bursts from 100 Hz to 5 kHz, but ABR-audiograms revealed major differences in auditory sensitivities, especially at higher frequencies (>1 kHz) where thresholds differed by up to 50 dB. These differences showed no apparent correspondence to the ability to produce sounds (vocal versus non-vocal species) or to the spectral content of species-specific sounds. All fishes have maximum sensitivity between 400 Hz and 1,500 Hz, whereas the major portion of the energy of acoustic signals was in the frequency range of 100–400 Hz (swimbladder drumming sounds) and of 1–3 kHz (stridulatory sounds). Species producing stridulatory sounds exhibited better high-frequency hearing sensitivity (pimelodids, doradids), except for callichthyids, which had poorest hearing ability in this range. Furthermore, fishes emitting both low- and high-frequency sounds, such as pimelodid and doradid catfishes, did not possess two corresponding auditory sensitivity maxima. Based on these results it is concluded that selective pressures involved in the evolution of the Weberian apparatus and the design of vocal signals in otophysines were others (primarily predator or prey detection in quiet freshwater habitats) than those serving to optimize acoustical communication.

Are hearing sensitivities of freshwater fish adapted to the ambient noise in their habitats

SUMMARY Several groups of fishes, among them two thirds of all freshwater fishes, have developed hearing specializations that enhance auditory sensitivity and broaden frequency ranges compared with hearing non-specialists (generalists), which lack such adaptations. It has been speculated that the enhanced sensitivities of these so-called hearing specialists have evolved in quiet habitats such as lakes, backwaters of rivers, slowly flowing streams or the deep sea. To test this hypothesis, noise levels and frequency spectra of four different freshwater habitats near Vienna, Austria (Danube River, Triesting stream, Lake Neusiedl, backwaters of the Danube River), were recorded and played back to native fish species while simultaneously measuring their auditory thresholds using the auditory evoked potential (AEP) recording technique. As a representative of hearing specialists, we chose the common carp (Cyprinus carpio, Cyprinidae) and for the hearing generalists the European perch (Perca fluviatilis, Percidae). Data show that the carps hearing is only moderately masked by the quiet habitat noise level of standing waters (mean threshold shift 9 dB) but is heavily affected by stream and river noise by up to 49 dB in its best hearing range (0.5-1.0 kHz). In contrast, the perchs hearing thresholds were only slightly affected (mean up to 12 dB, at 0.1 kHz) by the highest noise levels presented. Our results indicate that hearing abilities of specialists such as carp are well adapted to the lowest noise levels encountered in freshwater habitats and that their hearing is considerably masked in some parts of their distribution range. Hearing in non-specialists such as perch, on the other hand, is only slightly or not at all impaired in all habitats.

Correlation between auditory sensitivity and vocalization in anabantoid fishes

Abstract Several anabantoid species produce broad-band sounds with high-pitched dominant frequencies (0.8–2.5 kHz), which contrast with generally low-frequency hearing abilities in (perciform) fishes. Utilizing a recently developed auditory brainstem response recording-technique, auditory sensitivities of the gouramis Trichopsis vittata, T. pumila, Colisa lalia, Macropodus opercularis and Trichogaster trichopterus were investigated and compared with the sound characteristics of the respective species. All five species exhibited enhanced sound-detecting abilities and perceived tone bursts up to 5 kHz, which qualifies this group as hearing specialists. All fishes possessed a high-frequency sensitivity maximum between 800 Hz and 1500 Hz. Lowest hearing thresholds were found in T. trichopterus (76 dB re 1 μPa at 800 Hz). Dominant frequencies of sounds correspond with the best hearing bandwidth in T. vittata (1–2 kHz) and C. lalia (0.8–1 kHz). In the smallest species, T. pumila, dominant frequencies of acoustic signals (1.5–2.5 kHz) do not match lowest thresholds, which were below 1.5 kHz. However, of all species studied, T. pumila had best hearing sensitivity at frequencies above 2 kHz. The association between high-pitched sounds and hearing may be caused by the suprabranchial air-breathing chamber, which, lying close to the hearing and sonic organs, enhances both sound perception and emission at its resonant frequency.

Diversity in noise-induced temporary hearing loss in otophysine fishes

The effects of intense white noise (158 dB re 1 microPa for 12 and 24 h) on the hearing abilities of two otophysine fish species--the nonvocal goldfish Carassius auramus and the vocalizing catfish Pimelodus pictus--were investigated in relation to noise exposure duration. Hearing sensitivity was determined utilizing the auditory brainstem response (ABR) recording technique. Measurements in the frequency range between 0.2 and 4.0 kHz were conducted prior and directly after noise exposure as well as after 3, 7, and 14 days of recovery. Both species showed a significant loss of sensitivity (up to 26 dB in C. auratus and 32 dB in P. pictus) immediately after noise exposure, with the greatest hearing loss in the range of their most sensitive frequencies. Hearing loss differed between both species, and was more pronounced in the catfish. Exposure duration had no influence on hearing loss. Hearing thresholds of C. auratus recovered within three days, whereas those of P. pictus only returned to their initial values within 14 days after exposure in all but one frequency. The results indicate that hearing specialists are affected differently by noise exposure and that acoustic communication might be restricted in noisy habitats.

Sound Production and Acoustic Communication

Fishes have evolved a diversity of sound-generating organs. These include vibrating the swimbladder and pectoral girdle by rapidly contracting muscles or rubbing bony elements against each other (stridulation) and plucking enhanced tendons. While the former mechanisms produce low-frequency, often harmonic signals (< 500 Hz), the latter usually generate broad-band pulsed sounds with frequencies up to a few kHz. The restriction of fish sounds to lower frequencies limits the distances over which sounds can propagate, especially in shallow waters where sound transmission is negligible below a certain frequency (cutoff frequency).

Noise emission during the first powerboat race in an Alpine lake and potential impact on fish communities

In order to assess the effects of high-speed boating on fish communities, noise levels were measured during the first Class 1 powerboat race on the Austrian Lake Traunsee. The noise spectra were compared to natural ambient noise and hearing abilities of four native fish species. Sound pressure levels (SPLs) were significantly elevated during the training heats and the race compared with natural levels, reaching up to 128 dB re 1 microPa (instantaneous SPL) at a distance of 300 m to the powerboats. Continuous equivalent SPLs were significantly lower during training and the pole position race compared to the race itself because fewer boats were simultaneously on the lake. The hearing abilities of the native hearing specialists and generalists were investigated. While carp and roach (two cyprinids) showed enhanced auditory sensitivity typical for hearing specialists, perch and whitefish were much less sensitive to sounds. Comparisons between power boat noise spectra and audiograms showed that the cyprinids can detect the boats up to several hundred meters distance because the main noise energy is well within the most sensitive hearing range. The hearing generalists, however, probably only perceive the first harmonic of the boat noise at close distances.