Sound communication

peer reviewedAll anemonefish species can produce two types of sounds. The first class concerns agonistic sounds that are produced during territory defence and probably to establish social hierarchy between individuals. The second class relates to submissive sounds that are emitted in reaction to aggressive acts by dominant individuals. In both types of sounds, irrespective of the sexual status, frequency is highly related to fish size: smaller individuals produce pulses of higher frequency and shorter duration than larger individuals. Consequently, these sonic features within a group may convey information on the social rank of the emitter within the group. This relationship between fish size and both dominant frequency and pulse duration could concern all the Amphiprionini tribe. It highlights the use of a highly conservative vocalization mechanism. Aggressive sounds are initiated by buccal jaw teeth snapping caused by rapid mouth closure attributed to a sonic ligament. We hypothesize that the slam provokes bone vibrations. As the close association of the rib cage and the swimbladder wall would be analogous to a membrane loudspeaker, vibrations would cause shaking of this membrane and cause the second part of the sound. The sound-producing mechanism related to submissive sounds is still not known

Auditory evoked potential audiograms in post-settlement stage individuals of coral reef fishes

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Interspecific variation of calls in clownfishes: degree of similarity in closely related species

Clownfishes are colorful coral reef fishes living in groups in association with sea anemones throughout the Indo-Pacific Ocean. Within their small societies, size hierarchy determines which fish have access to reproduction. These fishes are also prolific callers whose aggressive sounds seem to play an important role in the social hierarchy. Agonistic interactions being involved in daily behaviour suggest how acoustic communication might play an important role in clownfish group. Sounds were recorded and compared in fourteen clownfish species (some of which have never been recorded before) to evaluate the potential role of acoustic communication as an evolutionary driving force. Surprisingly, the relationship between fish size and both dominant frequency and pulse duration is not only species-specific; all the specimens of the 14 species are situated on exactly the same slope, which means the size of any Amphiprion can be predicted by both acoustic features. The number of pulses broadly overlaps among species, whereas the pulse period displays the most variation even if it shows overlap among sympatric species. Sound comparisons between three species (A. akallopisos, A. ocellaris and A. frenatus) having different types of teeth and body shape do not show differences neither in the acoustic waveform nor in the power spectrum. Significant overlap in acoustic features demonstrates that the sound-producing mechanism is highly conservative among species. Differences in the calls of some species are due to size dimorphism and the sound variation might be in this case a by-product. This morphological constraint does not permit a consideration of acoustic communication as the main driving force in the diversification of clownfishes. Moreover, calls are not produced to find mate and consequently are less subject to variations due to partner preference, which restricts the constraints of diversification. Calls are produced to reach and defend the competition to mate access. However, differences in the pulse period between cohabiting species show that, in some case, sounds can help to differentiate the species, to prevent competition between cohabiting species and to promote the diversification of taxa

Comparative study on sound production in different Holocentridae species

<p/> <p>Background</p> <p>Holocentrids (squirrelfish and soldierfish) are vocal reef fishes whose calls and sound-producing mechanisms have been studied in some species only. The present study aims to compare sound-producing mechanisms in different Holocentridae genera (<it>Holocentrus</it>, <it>Myripristis</it>, <it>Neoniphon</it>, <it>Sargocentron</it>) from separate regions and, in some cases, at different developmental stages. An accurate comparison was made by recording six species while being hand-held, by observing TEM) the sonic muscles and by dissections of the sound-producing mechanism.</p> <p>Results</p> <p>In all these species, calls presented harmonics, their dominant frequency was between 80 and 130 Hz and they were composed of trains of 4 to 11 pulses with gradual increasing periods towards the end of the call. In each case, the calls did not provide reliable information on fish size. The sounds were produced by homologous fast-contracting sonic muscles that insert on articulated ribs whose proximal heads are integrated into the swimbladder: each pulse is the result of the back and forth movements of the ribs. Small differences in the shape of the oscillograms of the different species could be related to the number of ribs that are involved in the sound-producing mechanism. These fish species are able to make sounds as soon as they settle on the reef, when they are 40 days old. Comparison between <it>Neoniphon </it>from Madagascar and from Rangiroa in French Polynesia showed a new, unexpected kind of dialect involving differences at the level of pulse distribution. <it>Neoniphon </it>calls were characterised by a single pulse that was isolated at the beginning of the remaining train in Madagascar whereas they did not show any isolated single pulses at the beginning of the call in Rangiroa.</p> <p>Conclusion</p> <p>This family cannot use the acoustic fundamental frequencies (or pulse periods) of grunts to infer the size of partners. Pulse duration and number of pulses are statistically related to fish size. However, these characteristics are poorly informative because the correlation slope values are weak. It remains other features (sound amplitude, resistance to muscle fatigue, calling frequency) could be used to assess the body size. Characteristics of the sound producing mechanisms are conservative. All species possess fast-contracting muscles and have the same kind of sound producing mechanism. They do show some change between clades but these differences are not important enough to deeply modify the waveforms of the calls. In this case, our description of the grunt could be considered as the signature for the holocentrid family and can be used in passive acoustic monitoring.</p

Anthropogenic noise playback impairs embryonic development and increases mortality in a marine invertebrate

Human activities can create noise pollution and there is increasing international concern about how this may impact wildlife. There is evidence that anthropogenic noise may have detrimental effects on behaviour and physiology in many species but there are few examples of experiments showing how fitness may be directly affected. Here we use a split-brood, counterbalanced, field experiment to investigate the effect of repeated boat-noise playback during early life on the development and survival of a marine invertebrate, the sea hare Stylocheilus striatus at Moorea Island (French Polynesia). We found that exposure to boat-noise playback, compared to ambient-noise playback, reduced successful development of embryos by 21% and additionally increased mortality of recently hatched larvae by 22%. Our work, on an understudied but ecologically and socio-economically important taxon, demonstrates that anthropogenic noise can affect individual fitness. Fitness costs early in life have a fundamental influence on population dynamics and resilience, with potential implications for community structure and function

Ciclo diurno de dos sonidos recurrentes de peces en arrecifes de coral mesofóticos

Mesophotic coral ecosystems (MCEs) are the deepest part of tropical coral reefs, ranging from depths of 30 to over 170 m. Despite their significance, MCEs remain largely unexplored due to the challenges associated with accessing these depths. However, the application of passive acoustic monitoring methods (PAM) is a suitable approach for studying fish communities within these unique habitats. In French Polynesia, recent PAM studies have unveiled a higher occurrence of frequency-modulated fish sounds in MCEs than in shallower reef environments. This study aims to further enhance our understanding of fish sounds in MCEs by examining their diel patterns, focusing specifically on the two most abundant frequency-modulated fish sounds that were recorded at depths of 60 and 120 m at six Polynesian islands. Both sound types occurred predominantly during the beginning and the end of nocturnal periods. The presence and abundance of these sounds exhibited variation between the islands, highlighting potential regional disparities in vocal activity or the bathymetric distribution of the sound-producing species. By characterizing the diel cycles and bathymetric differences in relation to their geographical distribution, this study offers preliminary insights into identifying the potential sound-producing species.Los Ecosistemas de Coral Mesofótico (MCEs, por sus siglas en inglés) representan la parte más profunda de los arrecifes de coral tropicales, con profundidades que van desde los 30 metros hasta más de 170 metros. A pesar de su importancia, los MCEs siguen siendo en gran parte inexplorados debido a los desafíos asociados con el acceso a estas profundidades. Sin embargo, la aplicación de métodos de Monitoreo Acústico Pasivo (PAM, por sus siglas en inglés) presenta un enfoque adecuado para estudiar las comunidades de peces dentro de estos hábitats únicos. En la Polinesia francesa, estudios recientes de PAM han revelado una mayor ocurrencia de sonidos de peces de modulación de frecuencia en los MCEs en comparación con los ambientes de arrecifes menos profundos. Este estudio tiene como objetivo mejorar aún más nuestra comprensión de los sonidos de los peces en los MCEs mediante el examen de sus patrones diurnos, centrándose específicamente en los dos sonidos de peces de modulación de frecuencia más abundantes que fueron registrados a profundidades de 60 metros y 120 metros en seis islas distintas de la Polinesia. Ambos tipos de sonidos ocurrieron predominantemente al comienzo y al final de los períodos nocturnos. La presencia y abundancia de estos sonidos mostraron variaciones entre las diferentes islas, resaltando posibles disparidades regionales en la actividad vocal o en la distribución batimétrica de las especies que producen los sonidos. Al caracterizar los ciclos diurnos y las diferencias batimétricas en relación con su distribución geográfica, esta investigación ofrece conocimientos preliminares para identificar las posibles especies que producen estos sonidos

Sound production in four damselfish (Dascyllus) species: phyletic relationships?

peer reviewedMost studies of fish sounds show that the sounds are species-specific, with unique spectral and timing characteristics. This raises the question as to whether these sounds can be used to understand phyletic relationships between species and which acoustic parameters are subject to variation between species. In the present study, 597 sounds (and 2540 pulses) related to signal jumps of four Dascyllus species (Dascyllus aruanus, Dascyllus trimaculatus, Dascyllus albisella, and Dascyllus flavicaudus) from different geographic regions (Madagascar, Moorea, Rangiroa, and Hawaii) were analysed. It was possible to discern species-specific sounds, but also variation in sounds between populations. Large variations in sound length were found between Dascyllus species, whereas differences in interpulse duration were found to be variable between populations. In the regions where species live in sympatry, it appears that they restrict the variability in their sounds. This could comprise evidence of adaptation with character displacement of sonic characteristics where different species co-occur. However, sonic characteristics still overlapped substantially between species, suggesting that females would need to sample more than one sound and potentially use other cues to discriminate between species