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Although it is clear that settlement-stage fi sh larvae can detect reef sound at distances
of a few 100 m (Wright et al. 2010 ), it is less understood how such auditory sensitivity develops throughout the larval phase and how the auditory abilities vary
between species.
The early hearing capabilities in several pelagic reef Pomacentrid species have
been examined during larval stages with mixed results. Using AEP recordings,
Egner and Mann ( 2005 ) reported an ontogenetic change in the auditory sensitivity of
the sergeant major damselfi sh ( Abudefauf saxatilis , Pomacentridae) (Fig. 4 ).
Curiously, at 100 and 200 Hz there was a signifi cant effect of size on hearing thresholds with auditory sensitivity decreasing with standard fi sh length. In addition, maximum detectable frequency increased with SL with the larger fi sh (>50 mm SL) being
more responsive at higher frequencies (1000–1600 Hz). This study suggests that
sound may play a role in short-range orientation (<1 km) of pelagic larvae to reefs.
In contrast, both hearing improvement and absence of developmental changes
have been described among other species within the Pomacentridae family. Kenyon
( 1996 ), through classical conditioning experiments conducted in a standing wave
tube to control sound pressure and particle motion cues, showed that the bicolor
damselfi sh ( Stegastes partitus ) exhibit an ontogenetic increase in auditory sensitivity, up to 45 dB re 1 μPa at their most sensitive frequency of 300 Hz. Likewise,
Wright et al. ( 2005 ) also reported increases in AEP responses of roughly 8 dB re 1
μPa at 100 and 600 Hz between pre-settlement (12–15 mm SL) and post-settlement
(15–17 mm SL) in juvenile damselfi sh ( Stegastes nagasakiensis ).
Simpson et al. ( 2005 ) investigated sound detection in early embryonic stages of
two clownfi sh species, the saddle anemone fi sh ( Amphiprion ephippium ) and the red
anemone fi sh ( A. rubrocinctus , Pomacentridae), by measuring the heart rate of
embryos while exposed to sounds in the range of 100–1200 Hz at 80–150 dB (re 1
μPa at 1 m). The authors found that after 3 dpf the heart rate of larvae increased
signifi cantly in response to sound. Throughout development, larvae responded to
sound via changes in heart rate to large range of frequencies from 400–700 Hz at 3
dpf and 100–1200 Hz at 9 dpf. Larval auditory sensitivity was also shown to increase
during development approximately 51 dB re 1 μPa at 700 Hz.
More recently, Wright et al. ( 2011 ) described using AEP recordings ontogenetic
increases in auditory sensitivity ranging up to 25 dB re 1 μPa in three pelagic coralreef fi sh species. Ontogenetic increases in auditory sensitivity were demonstrated
for larval stages of carangid ( Caranx ignobilis ), serranid ( Epinephalus coioides ),
and polynemid ( Eleutheronema tetradactulum ) fi shes ranging from 9 to 28 mm
TL. However, fi sh larvae from two other species examined, Epinephelus fuscoguttatus (Serranidae) and Macquaria novemaculeata (Percichthyidae), did not show
any ontogenetic changes in auditory sensitivity across different-sized groups. Such
species-specifi c variation in auditory sensitivity during ontogeny suggests that both
the developmental stage and species are important factors to consider when investigating whether sound may be a salient cue used by pelagic larvae for navigation and
orientation to reef habitats.
R.O. Vasconcelos et al.
Although it is clear that settlement-stage fi sh larvae can detect reef sound at distances
of a few 100 m (Wright et al. 2010 ), it is less understood how such auditory sensitivity develops throughout the larval phase and how the auditory abilities vary
between species.
The early hearing capabilities in several pelagic reef Pomacentrid species have
been examined during larval stages with mixed results. Using AEP recordings,
Egner and Mann ( 2005 ) reported an ontogenetic change in the auditory sensitivity of
the sergeant major damselfi sh ( Abudefauf saxatilis , Pomacentridae) (Fig. 4 ).
Curiously, at 100 and 200 Hz there was a signifi cant effect of size on hearing thresholds with auditory sensitivity decreasing with standard fi sh length. In addition, maximum detectable frequency increased with SL with the larger fi sh (>50 mm SL) being
more responsive at higher frequencies (1000–1600 Hz). This study suggests that
sound may play a role in short-range orientation (<1 km) of pelagic larvae to reefs.
In contrast, both hearing improvement and absence of developmental changes
have been described among other species within the Pomacentridae family. Kenyon
( 1996 ), through classical conditioning experiments conducted in a standing wave
tube to control sound pressure and particle motion cues, showed that the bicolor
damselfi sh ( Stegastes partitus ) exhibit an ontogenetic increase in auditory sensitivity, up to 45 dB re 1 μPa at their most sensitive frequency of 300 Hz. Likewise,
Wright et al. ( 2005 ) also reported increases in AEP responses of roughly 8 dB re 1
μPa at 100 and 600 Hz between pre-settlement (12–15 mm SL) and post-settlement
(15–17 mm SL) in juvenile damselfi sh ( Stegastes nagasakiensis ).
Simpson et al. ( 2005 ) investigated sound detection in early embryonic stages of
two clownfi sh species, the saddle anemone fi sh ( Amphiprion ephippium ) and the red
anemone fi sh ( A. rubrocinctus , Pomacentridae), by measuring the heart rate of
embryos while exposed to sounds in the range of 100–1200 Hz at 80–150 dB (re 1
μPa at 1 m). The authors found that after 3 dpf the heart rate of larvae increased
signifi cantly in response to sound. Throughout development, larvae responded to
sound via changes in heart rate to large range of frequencies from 400–700 Hz at 3
dpf and 100–1200 Hz at 9 dpf. Larval auditory sensitivity was also shown to increase
during development approximately 51 dB re 1 μPa at 700 Hz.
More recently, Wright et al. ( 2011 ) described using AEP recordings ontogenetic
increases in auditory sensitivity ranging up to 25 dB re 1 μPa in three pelagic coralreef fi sh species. Ontogenetic increases in auditory sensitivity were demonstrated
for larval stages of carangid ( Caranx ignobilis ), serranid ( Epinephalus coioides ),
and polynemid ( Eleutheronema tetradactulum ) fi shes ranging from 9 to 28 mm
TL. However, fi sh larvae from two other species examined, Epinephelus fuscoguttatus (Serranidae) and Macquaria novemaculeata (Percichthyidae), did not show
any ontogenetic changes in auditory sensitivity across different-sized groups. Such
species-specifi c variation in auditory sensitivity during ontogeny suggests that both
the developmental stage and species are important factors to consider when investigating whether sound may be a salient cue used by pelagic larvae for navigation and
orientation to reef habitats.
R.O. Vasconcelos et al.