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Ontogenetic Development of Auditory Sensitivity and Sound Production in the Squeaker Catfish Synodontis Schoutedeni

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Ontogenetic Development of Auditory Sensitivity and Sound Production in the Squeaker Catfish Synodontis Schoutedeni

Walter Lechner et al. BMC Biol.

Abstract

Background: Surveys of ontogenetic development of hearing and sound production in fish are scarce, and the ontogenetic development of acoustic communication has been investigated in only two fish species so far. Studies on the labyrinth fish Trichopsis vittata and the toadfish Halobatrachus didactylus show that the ability to detect conspecific sounds develops during growth. In otophysine fish, which are characterized by Weberian ossicles and improved hearing sensitivities, the ontogenetic development of sound communication has never been investigated. We analysed the ontogeny of the auditory sensitivity and vocalizations in the mochokid catfish Synodontis schoutedeni. Mochokid catfishes of the genus Synodontis are commonly called squeakers because they produce broadband stridulation sounds during abduction and adduction of pectoral fin spines. Fish from six different size groups - from 22 mm standard length to 126 mm - were studied. Hearing thresholds were measured between 50 Hz and 6 kHz using the auditory evoked potentials recording technique; stridulation sounds were recorded and their sound pressure levels determined. Finally, absolute sound power spectra were compared to auditory sensitivity curves within each size group.

Results: The smallest juveniles showed the poorest hearing abilities of all size groups between 50 and 1,000 Hz and highest hearing sensitivity at 5 and 6 kHz. The duration of abduction and adduction sounds and the pulse period increased and sound pressure level (in animals smaller than 58 mm) increased, while the dominant frequency of sounds decreased with size in animals larger than 37 mm. Comparisons between audiograms and sound spectra revealed that the most sensitive frequencies correlate with the dominant frequencies of stridulation sounds in all S. schoutedeni size groups and that all specimens are able to detect sounds of all size groups.

Conclusions: This study on the squeaker catfish S. schoutedeni is the first to demonstrate that absolute hearing sensitivity changes during ontogeny in an otophysine fish. This contrasts with prior studies on two cypriniform fish species in which no such change could be observed. Furthermore, S. schoutedeni can detect conspecific sounds at all stages of development, again contrasting with prior findings in fishes.

Figures

Figure 1
Figure 1
Auditory evoked potential audiograms of the size groups investigated. Mean hearing thresholds of the size groups XXS (N = 12), XS (N = 6), S (N = 6), M (N = 5), L (N = 4) and XL (N = 6) of Synodontis schoutedeni tested. Catfish pictures show representative specimens of group XXS (left) and XL (right) drawn in proportional scale for comparative purposes.
Figure 2
Figure 2
Correlations between auditory thresholds and fish size at frequencies tested. Semilog plots of hearing thresholds of each individual against log of standard-length at each frequency tested. N = 39 at each frequency except 6000 Hz (N = 34). Pearson's correlation coefficients and significances are given in graphs. Regression equations: x = log standard length, y = hearing threshold (dB re 1 μPa); 50 Hz: y = -1.92x + 117.79; 100 Hz: y = -21,33x + 125.27; 300 Hz: y = -29.91x + 130.33; 500 Hz: y = -21.32x + 111.67; 800 Hz: y = -22.84x + 114.81; 1000 Hz: y = -21.44x + 112.46; 2000 Hz: y = -11.57x + 95.77; 3000 Hz: y = -1.57x + 81.83; 4000 Hz: y = 5.34x + 74.30; 5000 Hz: y = 15.83x + 60.13; 6000 Hz: y = 19.68x + 54.78.
Figure 3
Figure 3
Sonagram and oscillogram of stridulation sounds. Sonagram (top) and oscillogram (below) of adduction sounds (left) and abduction sounds (right) of representatives of group XXS (A) and group XL (B). Sampling frequency 44.1 kHz, filter bandwidth 650 Hz for XXS and 600 Hz for XL, 75% overlap, Hanning window.
Figure 4
Figure 4
Correlations between sound characteristics and standard length. Plots of sound characteristics against standard length. Pearson's correlation coefficients and significances are given in graphs. 4A: Segmented linear regression plot SPL against SL, breaking point 57.6 mm SL, regression equations (y = SPL): SL < 57.6 mm: N = 21, SPL = 0.36 SL + 109.76, SL > 57.6 mm: N = 19, SPL = 0.02 SL + 129.10; 4B: Pulse-period (adduction) against SL: N = 40, pulse period = 0.04 SL + 1.93; 4C: Duration of adduction sounds against SL: N = 40, duration = 0.30 SL + 19.59; 4D: Duration of abduction sounds against SL: N = 40, duration = 0.39 SL + 39.69; 4E: Segmented linear regression plot of dominant frequency against SL, breaking point 36.91 mm SL: SL < 36.91 mm: N = 9, dom. freq. = 101.35 SL - 741.89, SL > 36.91 mm: N = 31, dom. freq. = - 7.04 SL + 1469.41; 4F: Segmented linear regression plot bandwidth of sounds 10 dB below SPL of peak frequency against SL, breaking point 73.43 mm SL: SL < 73.43 mm: N = 24, bandwidth = - 53.42 SL + 5174.77, SL > 73.43 mm: N = 11, bandwidth = - 9.36 SL + 2210.15. Regression lines in 4A, 4E and 4F were drawn according to the results of the segmented linear regression calculation. Note two p and r values (one for each regression) in figures 4A, 4E and 4F.
Figure 5
Figure 5
Relations between auditory thresholds and sound spectra. Cepstrum-smoothed sound power spectra of stridulatory sounds calculated for a distance of 5 cm from the hydrophone compared to auditory thresholds in the six size groups tested. For size-ranges see material and methods.
Figure 6
Figure 6
Temporal sound characteristics of single calls. Oscillogram of a single stridulation sound of S. schoutedeni showing temporal sound characteristics analysed (PP = pulse period).
Figure 7
Figure 7
Cepstrum-smoothed power spectrum of stridulatory sounds of a size group indicating the calculation of the frequency bandwidth used for analysis. The minimum and maximum frequencies 10 dB below the dominant frequency were determined and the bandwidth calculated.

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References

    1. Hawkins AD, Myrberg AA. , Jr. In: Bioacoustics, a Comparative Approach. Lewis B, editor. London: Academic Press; 1983. Hearing and sound communication underwater; pp. 347–405.
    1. Popper AN, Fay RR. In: Comparative Hearing: Fish and Amphibians. Fay RR, Popper AN, editor. New York: Springer Verlag; 1999. The auditory periphery in fishes; pp. 43–100.
    1. Ferraris CJ Jr. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa. 2007;1418:1–628.
    1. Lechner W, Ladich F. Size matters: diversity in swimbladders and Weberian ossicles affects hearing in catfishes. J Exp Biol. 2008;211:1681–1689. doi: 10.1242/jeb.016436. - DOI - PubMed
    1. Dmitrieva LP, Gottlieb G. Development of brainstem auditory pathway in mallard duck embryos and hatchlings. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 1992;171:665–671. - PubMed

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