231
within the same species that will allow the assessment of these physiological
measures at different auditory processing levels. These types of comparisons should
provide insights into what information we can and cannot glean about auditory
capabilities from singular recording methods within an individual species.
1.3 Study Species: Hawaiian Sergeant Damselfi sh, Abudefduf
abdominalis
Damselfi shes (family Pomacentridae) are a large group of reef fi shes with approximately 360 species. Several damselfi sh genera are known to produce primarily
broadband pulsed sounds during territorial and reproductive behavior, which conveys information about species, sex, body size, reproductive readiness, and aggression level (reviewed in Amorim 2006 ). Previous studies also demonstrate that both
the frequency and temporal patterning of the pulsed sounds are critically important
for acoustic communication in behaving pomacentrid fi shes (Myrberg et al. 1993 ;
Lobel and Mann 1995 ; Myrberg and Lugli 2006 ). The Hawaiian sergeant fi sh,
Abudefduf abdominalis , is a colonial benthic-spawning damselfi sh that produces
low-frequency, low-intensity pulsed sounds associated with reproductive and agonistic behaviors (Fig. 1 ). Further, the frequency hearing range matches the spectral
content of sounds produced by naturally behaving wild fi sh (Maruska et al. 2007 ).
During the protracted breeding season, males clean and prepare benthic substrates
to attract females for courtship and spawning. After spawning, males remain to
guard the nest, care for the developing young until they hatch, and continue to court
and spawn with additional females over the course of the breeding season. Similar
to other damselfi shes examined thus far [see Zelick et al. 1999 ; Bass and McKibben
2003 ; Amorim 2006 for reviews], A. abdominalis does not appear to possess any
special adaptations to enhance the detection of sound pressure, and the anterior edge
of the swim bladder is typically several millimeters caudal to the otic capsule
(~1.5–3.0 % of SL; Fig. 2a ). This species is well suited for comparing different
electrophysiological techniques that assess fi sh hearing because the behaviors associated with sound production including the temporal and spectral sound characteristics, central auditory nerve projections, and response properties of auditory
neurons in the brain are already described (Maruska et al. 2007 ; Maruska and Tricas
2009a , b , 2011 ). This information facilitates interpretation of the auditory recording
data in a biologically relevant context.
The goal of this study was to fi rst characterize the AEP thresholds from the
saccule (saccular potentials) in the Hawaiian sergeant fi sh, and then to compare
them to the thresholds measured by the AEP and extracellular single unit recording
techniques from the brain in this same species. These data are signifi cant because no
other study has directly compared auditory threshold measurements obtained by
several different electrophysiological-based techniques from different auditory processing levels in a single soniferous fi sh under similar testing conditions.
Comparison of Electrophysiological Auditory Measures in Fishes
within the same species that will allow the assessment of these physiological
measures at different auditory processing levels. These types of comparisons should
provide insights into what information we can and cannot glean about auditory
capabilities from singular recording methods within an individual species.
1.3 Study Species: Hawaiian Sergeant Damselfi sh, Abudefduf
abdominalis
Damselfi shes (family Pomacentridae) are a large group of reef fi shes with approximately 360 species. Several damselfi sh genera are known to produce primarily
broadband pulsed sounds during territorial and reproductive behavior, which conveys information about species, sex, body size, reproductive readiness, and aggression level (reviewed in Amorim 2006 ). Previous studies also demonstrate that both
the frequency and temporal patterning of the pulsed sounds are critically important
for acoustic communication in behaving pomacentrid fi shes (Myrberg et al. 1993 ;
Lobel and Mann 1995 ; Myrberg and Lugli 2006 ). The Hawaiian sergeant fi sh,
Abudefduf abdominalis , is a colonial benthic-spawning damselfi sh that produces
low-frequency, low-intensity pulsed sounds associated with reproductive and agonistic behaviors (Fig. 1 ). Further, the frequency hearing range matches the spectral
content of sounds produced by naturally behaving wild fi sh (Maruska et al. 2007 ).
During the protracted breeding season, males clean and prepare benthic substrates
to attract females for courtship and spawning. After spawning, males remain to
guard the nest, care for the developing young until they hatch, and continue to court
and spawn with additional females over the course of the breeding season. Similar
to other damselfi shes examined thus far [see Zelick et al. 1999 ; Bass and McKibben
2003 ; Amorim 2006 for reviews], A. abdominalis does not appear to possess any
special adaptations to enhance the detection of sound pressure, and the anterior edge
of the swim bladder is typically several millimeters caudal to the otic capsule
(~1.5–3.0 % of SL; Fig. 2a ). This species is well suited for comparing different
electrophysiological techniques that assess fi sh hearing because the behaviors associated with sound production including the temporal and spectral sound characteristics, central auditory nerve projections, and response properties of auditory
neurons in the brain are already described (Maruska et al. 2007 ; Maruska and Tricas
2009a , b , 2011 ). This information facilitates interpretation of the auditory recording
data in a biologically relevant context.
The goal of this study was to fi rst characterize the AEP thresholds from the
saccule (saccular potentials) in the Hawaiian sergeant fi sh, and then to compare
them to the thresholds measured by the AEP and extracellular single unit recording
techniques from the brain in this same species. These data are signifi cant because no
other study has directly compared auditory threshold measurements obtained by
several different electrophysiological-based techniques from different auditory processing levels in a single soniferous fi sh under similar testing conditions.
Comparison of Electrophysiological Auditory Measures in Fishes