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| Leroy, Emmanuelle C.; Samaran, Flore; Stafford, Kathleen M.; Bonnel, Julien; Royer, Jean-yves. |
| The southern Indian Ocean is believed to be a natural territory for blue and fin whales. However, decades after commercial and illegal whaling decimated these populations, little is known about their current status, seasonal habitat or movements. Recent passive acoustic studies have described the presence of 4 acoustic populations of blue whales (Antarctic and 3 'pygmy' types), but are generally limited temporally and geographically. Here, we examine up to 7 yr of continuous acoustic recordings (2010-2016) from a hydrophone network of 6 widely spaced sites in the southern Indian Ocean, looking for the presence of Antarctic and pygmy blue and fin whales. Power spectral density analyses of characteristic and distinct frequency bands of these species show... |
| Tipo: Text |
Palavras-chave: Pygmy blue whales; Antarctic blue whales; Fin whales; Southern Indian Ocean; Passive acoustic monitoring; Sympatry. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00516/62731/67110.pdf |
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| Jézéquel, Youenn; Chauvaud, Laurent; Bonnel, Julien. |
| The detection ranges of broadband sounds produced by marine invertebrates are not known. To address this deficiency, a linear array of hydrophones was built in a shallow water area to experimentally investigate the propagation features of the sounds from various sizes of European spiny lobsters (Palinurus elephas), recorded between 0.5 and 100 m from the animals. The peak-to-peak source levels (SL, measured at one meter from the animals) varied significantly with body size, the largest spiny lobsters producing SL up to 167 dB re 1 µPa2. The sound propagation and its attenuation with the distance were quantified using the array. This permitted estimation of the detection ranges of spiny lobster sounds. Under the high ambient noise conditions recorded in... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00630/74201/73827.pdf |
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| Leroy, Emmanuelle C; Royer, Jean-yves; Bonnel, Julien; Samaran, Flore. |
| In the past decades, in the context of a changing ocean submitted to an increasing human activity, a progressive decrease in the frequencies (pitch) of blue whale vocalizations has been observed worldwide. Its causes, of natural or anthropogenic nature, are still unclear. Based on 7years of continuous acoustic recordings at widespread sites in the southern Indian Ocean, we show that this observation stands for five populations of large whales. The frequency of selected units of vocalizations of fin, Antarctic, and pygmy blue whales has steadily decreased at a rate of a few tenths of hertz per year since 2002. In addition to this interannual frequency decrease, blue whale vocalizations display seasonal frequency shifts. We show that these intra-annual... |
| Tipo: Text |
Palavras-chave: Large baleen whales; Blue whale calls; Frequency shifts; Frequency decrease; Ambient noise; Bioacoustics. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00516/62730/67109.pdf |
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| Leroy, Emmanuelle C.; Samaran, Flore; Bonnel, Julien; Royer, Jean-yves. |
| Passive acoustic monitoring is an efficient way to provide insights on the ecology of large whales. This approach allows for long-term and species-specific monitoring over large areas. In this study, we examined six years (2010 to 2015) of continuous acoustic recordings at up to seven different locations in the Central and Southern Indian Basin to assess the peak periods of presence, seasonality and migration movements of Antarctic blue whales (Balaenoptera musculus intermedia). An automated method is used to detect the Antarctic blue whale stereotyped call, known as Z-call. Detection results are analyzed in terms of distribution, seasonal presence and diel pattern of emission at each site. Z-calls are detected year-round at each site, except for one... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00357/46828/46699.pdf |
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| Jezequel, Youenn; Bonnel, Julien; Coston-guarini, Jennifer; Guarini, Jean-marc; Chauvaud, Laurent. |
| Experiments in marine behavioural ecology rely heavily on observations made in tanks. However, when studying acoustic behaviours of marine animals in confined volumes, the effects of reverberation must be characterized, something that has been overlooked in parts of the marine ecology literature. In this study, we characterized reverberation in tanks using an artificial sound source and examined the implications for bioacoustic studies using sounds emitted by the European lobster Homarus gammarus during feeding and in response to stress. Broadband and transient sounds commonly produced by crustaceans were severely impacted by reverberation such that their spectral characteristics and pulse width durations could not be assessed. In contrast, low-frequency... |
| Tipo: Text |
Palavras-chave: European lobster; Passive acoustics; Tanks; Reverberation; Rattle; Buzzing sound; Spectral analysis. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00439/55080/56512.pdf |
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