Figure 1.
Oscillograms of an AEP and a click stimulus.
AEP of a S. glanis in response to the click stimulus presented 28 dB above hearing threshold. The first, second and third positive peak (P1, P2, P3) are labelled. The double-headed arrow indicates the latency measured from the onset of the click stimulus to the second positive peak (P2).
Figure 2.
Auditory evoked potential audiogram at 15°C and 25°C.
Mean hearing thresholds of C. carpio kept 15°C, 25°C and 15°C repeated. N = 9.
Table 1.
Mean (± S.E.) hearing thresholds of C. carpio measured at 15°C, 25°C and 15°C repeated. N = 9.
Figure 3.
Auditory evoked potential audiogram at 15°C and 25°C.
Mean hearing thresholds of S. glanis kept at 15°C, 25°C and 15°C repeated. N = 8.
Table 2.
Mean (± S.E.) hearing thresholds of S. glanis measured at 15°C, 25°C and 15°C repeated. N = 8.
Table 3.
Mean differences in hearing sensitivity of C. carpio and S. glanis, between the two tested temperatures (mean of 15°C and 15°C repeated) and 25°C.
Figure 4.
AEPs of one specimen of C. carpio in response to a single-click stimulus.
Click stimulus presented 28 dB above hearing thresholds at both temperatures. Arrows indicate onset. The vertical dashed line indicates the position of the P2 peak at 25°C relative to the P2 peak at 15°C and 15°C repeated.
Figure 5.
Latency between the onset of the click and the second positive peak.
Mean (+ S.E.) latency of C. carpio kept at 15°C, 25°C and 15°C repeated. N = 9. Different letters (a, b) indicate significant differences between temperatures (p≤0.05).
Table 4.
Mean (± S.E.) latency of the second positive peaks (P2) of C. carpio and S. glanis measured at 15°C, 25°C and 15°C repeated calculated as the time period between the onset of a single click stimulus and the second positive peak.
Figure 6.
AEPs of one specimen of S. glanis in response to a single-click stimulus.
Click stimulus was presented 28 dB above hearing thresholds at both temperatures. Arrows indicate onset of the single-click stimulus. The vertical dashed line indicates the position of the P2 peak at 25°C relative to the P2 peak at 15°C and 15°C repeated.
Figure 7.
Latency between the onset of the click and the second positive peak.
Mean (+ S.E.) latency of S. glanis kept at 15°C, 25°C and 15°C repeated. N = 8. Different letters (a, b) indicate significant differences between temperatures (p≤0.05).
Figure 8.
Comparison of the changes in hearing sensitivity in eurythermal (solid lines) and stenothermal (dashed lines) otophysines.
C. carpio and S. glanis (recent study, 15°C vs. 25°C), I. punctatus (Wysocki et al., 2009: 18°C vs. 26°C), Amazonian catfishes P. pictus (Wysocki et al., 2009: 22°C vs. 30°C) and P. armatulus (Papes and Ladich, 2011; 22°C vs. 30°C).