References of "Kever, Loïc"
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See detailEnvironmental constraints drive the partitioning of the soundscape in fishes
Ruppé, Laetitia; Clément, Gaël; Herrel, Anthony et al

in Proceedings of the National Academy of Sciences of the United States of America (2015)

The underwater environment is more and more being depicted as particularly noisy, and the inventory of calling fishes is continuously increasing. However, it currently remains unknown how species share ... [more ▼]

The underwater environment is more and more being depicted as particularly noisy, and the inventory of calling fishes is continuously increasing. However, it currently remains unknown how species share the soundscape and are able to communicate without misinterpreting the messages. Different mechanisms of interference avoidance have been documented in birds, mammals, and frogs, but little is known about interference avoidance in fishes. How fish thus partition the soundscape underwater remains unknown, as acoustic communication and its organization have never been studied at the level of fish communities. In this study, passive acoustic recordings were used to inventory sounds produced in a fish community (120 m depth) in an attempt to understand how different species partition the acoustic environment. We uncovered an important diversity of fish sounds, and 16 of the 37 different sounds recorded were sufficiently abundant to use in a quantitative analysis. We show that sonic activity allows a clear distinction between a diurnal and a nocturnal group of fishes. Moreover, frequencies of signals made during the day overlap, whereas there is a clear distinction between the different representatives of the nocturnal callers because of a lack of overlap in sound frequency. This first demonstration, to our knowledge, of interference avoidance in a fish community can be understood by the way sounds are used. In diurnal species, sounds are mostly used to support visual display, whereas nocturnal species are generally deprived of visual cues, resulting in acoustic constraints being more important. [less ▲]

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See detailSound production in Onuxodon fowleri (Carapidae) and its amplification by the host shell
Kever, Loïc ULg; Colleye, Orphal ULg; Lugli, Marco et al

in Journal of Experimental Biology (2014), 217

Onuxodon species are well known for living inside pearl oysters. As in other carapids, their anatomy highlights their ability to make sounds but sound production has never been documented in Onuxodon ... [more ▼]

Onuxodon species are well known for living inside pearl oysters. As in other carapids, their anatomy highlights their ability to make sounds but sound production has never been documented in Onuxodon. This paper describes sound production in Onuxodon fowleri as well as the anatomy of the sound production apparatus. Single-pulsed sounds and multiple-pulsed sounds that sometimes last more than 3 s were recorded in the field and in captivity (Makemo Island, French Polynesia). These pulses are characterized by a broadband frequency spectrum from 100 to 1000 Hz. Onuxodon fowleri is mainly characterized by its ability to modulate the pulse period, meaning that this species can produce pulsed sounds and tonal-like sounds using the same mechanism. In addition, the sound can be remarkably amplified by the shell cavity (peak gain can exceed 10 dB for some frequencies). The sonic apparatus of O. fowleri is characterized by a rocker bone in front of the swimbladder, modified vertebrae and epineurals, and two pairs of sonic muscles, one of which (primary sonic muscle) inserts on the rocker bone. The latter structure, which is absent in other carapid genera, appears to be sexually dimorphic suggesting differences in sound production in males and females. Sound production in O. fowleri could be an example of adaptation where an animal exploits features of its environment to enhance communication. [less ▲]

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See detailAcoustic communication in Ophidiiformes: a case study using Ophidion rochei
Kever, Loïc ULg

Doctoral thesis (2014)

A ce jour, la biologie des Ophidiiformes reste peu connue car la majorité des espèces de ce groupe est inféodée aux eaux profondes. Celles qui ne le sont pas ont adopté un mode de vie nocturne, passant la ... [more ▼]

A ce jour, la biologie des Ophidiiformes reste peu connue car la majorité des espèces de ce groupe est inféodée aux eaux profondes. Celles qui ne le sont pas ont adopté un mode de vie nocturne, passant la journée cachées dans le sable, les anfractuosités d’un récif, ou un hôte invertébré en fonction de l’espèce considérée. Des études antérieures ont montré que les appareils de production de sons des Ophidioidei (Ophidiidae et Carapidae) sont complexes et présentent des différences interspécifiques marquées. De plus, l’oreille interne est généralement bien développée. Ces poissons étant actifs dans le noir, la communication acoustique devrait tenir un rôle important dans leur biologie. Ce travail de recherches s’attèle, par différentes approches, à étudier cette thématique en utilisant Ophidion rochei comme cas d’étude. Cet Ophidiidae psammobionte, présente un dimorphisme sexuel marqué au niveau de l’appareil de production de sons avec notamment la présence chez les mâles d’une structure minéralisée à l’avant de la vessie natatoire : le « rocker bone ». Pour mieux cerner la fonction des différentes structures intervenant dans la production et la réception de sons, des comparaisons ont été réalisées avec deux Carapidae : Onuxodon fowleri pour la production de sons et Carapus acus pour la réception de sons. L’étude établit que les espèces O. rochei et C. acus peuvent entendre les sons de leurs conspécifiques. Cependant, l’apport principal de cette partie est la démonstration que la grande taille des otolithes (en valeur absolue ou relative) n’est pas liée à de meilleures capacités auditives. De gros otolithes seraient principalement associés à une plus grande acuité de l’appareil stato-acoustique pour des espèces vivant dans des milieux accidentés. Les mâles et les femelles O. rochei produisent des sons uniquement après le coucher du soleil, durant la période de reproduction qui se déroule de juin à octobre. Ces sons apparaissent courts et tonaux chez les femelles, longs et pulsés chez les mâles. Ces différences dans les signatures acoustiques sont clairement liées au dimorphisme sexuel marqué bien qu’un patron moteur commun soit conservé chez les deux sexes. Brièvement, le muscle sonique dorsal servirait à mettre la vessie natatoire sous tension et le muscle sonique ventral serait à l’origine de l’émission de chaque pulse. De plus, les mâles présentent dans les caractéristiques sonores des différences individuelles marquées qui doivent refléter leur statut reproducteur et/ou leur taille. Chez O. fowleri, les deux sexes possèdent des « rocker bones » de taille et de forme différentes. Les sons enregistrés sont uniquement pulsés, mais ces poissons se distinguent de nombreux téléostéens par leur capacité à moduler le taux de pulsation. La comparaison des morphologies et mécanismes permet de soutenir l’hypothèse selon laquelle les « rocker bones » des deux taxa sont le résultat de convergences évolutives. Chez beaucoup de téléostéens, les sons sont utilisés pour supporter des stimuli d’ordre visuel. Les Ophidioidei étant actifs dans le noir, les contraintes évolutives ont principalement dû se marquer au niveau de l’appareil producteur de sons. En conclusion, la morphologie des appareils de production de sons, le dimorphisme sexuel, les caractéristiques uniques des sons produits, leur moment d’émission dans l’année et dans la journée soulignent la place importante de la communication acoustique au sein des Ophidioidei. [less ▲]

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See detailFin flickering and associated sounds in the cichlid fish Ophthalmotilapia ventralis: a preliminary study.
Kever, Loïc ULg; Poncin, Pascal ULg; Parmentier, Eric ULg

Poster (2014)

Fin flickering was defined as rapid movements of the fins. The behavioral function of such movements is however not well established. Depending on the species investigated, they were considered as comfort ... [more ▼]

Fin flickering was defined as rapid movements of the fins. The behavioral function of such movements is however not well established. Depending on the species investigated, they were considered as comfort movements (e.g. removal of minor irritations) or alarm for young. In the cichlid Etroplus maculatus they allow homogenous repartition of eggs on the substrate. We studied visual and acoustical behavior of five Ophthalmotilapia ventralis (two males and three females) reared in a 240 l tank. Pectoral fin flickering associated with sound production was often observed, especially from fish that established a territory. With the exception of the butterflish Chaetodon mutlicinctus and gouramis, this aspect of fin flickering is generally overlooked in teleosts. First observations support the fact that sounds (peak frequency and pulse duration: 562±95 Hz and 14±5 ms, respectively) are not emitted during all kinds of fin movements but mainly during some caudo-rostral horizontal fin sweeps. In-depth studies are however required to better characterize the movements and understand what morphological traits are responsible for the sound production. Further investigations are also needed to determine if fin flickering has a role in O. ventralis social interactions [less ▲]

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See detailA superfast muscle in the complex sonic apparatus of Ophidion rochei (Ophidiiformes): histological and physiological approaches
Kever, Loïc ULg; Boyle, Kelly; Dragicevic, Branko et al

in Journal of Experimental Biology (2014), 214

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See detailHearing capacities and otolith size in two ophidiiform species (Ophidion rochei and Carapus acus)
Kever, Loïc ULg; Colleye, Orphal ULg; Herrel, Anthony et al

in Journal of Experimental Biology (2014), 217

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See detailSound Characteristics and Complex Sonic Apparatus Morphologies in Two Ophidiiformes: Ophidion rochei (Ophidiidae) and Onuxodon fowleri (Carapidae)
Kever, Loïc ULg; Colleye, Orphal ULg; Lecchini, David et al

Conference (2013, July 14)

Ophidiiformes show complex and highly diverse sonic apparatus morphologies allowing them a great variety of calls. Some Ophidion (Ophidiidae) and all Onuxodon (Carapidae) species have in common, at the ... [more ▼]

Ophidiiformes show complex and highly diverse sonic apparatus morphologies allowing them a great variety of calls. Some Ophidion (Ophidiidae) and all Onuxodon (Carapidae) species have in common, at the front of the swimbladder, a mineralized structure called rocker bone. According to morphological observations, it probably results from adaptive convergence. Its evolutionary advantage remains however to be determined. Sonic apparatus morphology and sound characteristics were examined in Ophidion rochei from Dùlce-Glàva (Croatia) and in Onuxodon fowleri from Makemo (French Polynesia). The rocker bone is only present in males in O. rochei but in both sexes in O. fowleri. Onuxodon fowleri and male O. rochei produce calls that often last more than 1 s. Calls are composed of 1 to 41 pulses lasting for 21±10 ms in O. fowleri and 1 to 55 pulses lasting for 16±13 ms in O. rochei. Mean pulse periods are also relatively long, ca. 95 ms and 125 ms, respectively. Females of O. rochei produce short (ca. 20 ms) hum-like sounds that are characterized by shorter pulses (mean duration: 0.7±0.2 ms) and higher pulse rates (mean pulse period: 4±1 ms). Differences in sound characteristics are likely due to the rocker bone that most probably evolved in response to mechanical constraints acting on the swimbladder in O. fowleri and male O. rochei. Its presence suggests a sustained sound production was crucial in their evolutionary success. However, the sexual dimorphism observed in O. rochei but not in O. fowleri suggests differences in way of life. [less ▲]

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See detailSound production mechanism in Gobius paganellus (Gobiidae)
Parmentier, Eric ULg; Kever, Loïc ULg; Boyle, Kelly ULg et al

in Journal of Experimental Biology (2013), 216

Gobiidae, the largest fish family (>1500 species), has species from at least 10 genera that produce sounds for communication. Studies focused on goby sound production mechanisms have suggested that sounds ... [more ▼]

Gobiidae, the largest fish family (>1500 species), has species from at least 10 genera that produce sounds for communication. Studies focused on goby sound production mechanisms have suggested that sounds are produced by the forcible ejection of water through small apertures in the opercles (hydrodynamic mechanism). The present study was a multidisciplinary investigation (morphology, muscle histology, high-speed video, sound analysis and electromyography) of the sound emission mechanism in Gobius paganellus, which produces both pulsed and tonal calls. Two populations were used, from Brittany and Venice. In the French population, sounds were accompanied by a suite of coordinated movements of the buccal, branchial and opercular regions. This was not the case in the Venetian population, and thus the direct role of head movements in sound production was rejected. The hydrodynamic mechanism hypothesis was also rejected in G. paganellus on the basis of sound oscillogram shape and because sounds are still produced after the opercles and hyohyoid muscles are cut. The use of both electromyography and electron microscopy showed that the levator pectoralis muscle, which originates on the skull and inserts on the dorsal tip of the cleithrum, is involved in sound production. We propose that the contraction of this muscle and associated vibration of the large radials is used to make sounds. In addition, we propose that different sound types (pulsed sounds and tonal calls) could occur because of differences in fish size. [less ▲]

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See detailThe barbel-like specialization of the pelvic fins in Ophidion rochei (Ophidiidae)
Codina, Elisabet; Kever, Loïc ULg; Compère, Philippe ULg et al

in Journal of Morphology (2012), 273(12), 1367-1376

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See detailImportant variations in sonic apparatus morphology and sound characteristics of Ophidion rochei (Ophidiidae)
Kever, Loïc ULg; Dragicevic, Branko; Branko, Dulcic et al

Conference (2012)

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See detailCommunication acoustique chez les téléostéens
Kever, Loïc ULg; Parmentier, Eric ULg

Conference (2010, March 07)

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See detailDiversity in the sound production mechanism in Ophidiiformes
Parmentier, Eric ULg; Mann, David; Kever, Loïc ULg et al

Conference (2010)

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See detailDiversity and complexity in the acoustic behaviour of Dacyllus flavicaudus (Pomacentridae)
Parmentier, Eric ULg; Kever, Loïc ULg; Casadevall, Margardia et al

in Marine Biology (2010), 157(10), 2317-2327

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See detailVariations in sound production in <i>Dascyllus flavicaudus<i>
Kever, Loïc ULg; Lecchini, David; Parmentier, Eric ULg

Poster (2009, November 27)

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See detailVariations in sound production in <i>Dascyllus flavicaudus<i>
Kever, Loïc ULg; Lecchini, David; Parmentier, Eric ULg

Poster (2009, October)

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