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Acoustic measurements of post-dive cardiac responses in southern elephant seals ( Mirounga leonina ) during surfacing at sea

Louise Day 1 Joffrey Jouma'A 1 Julien Bonnel 2, 3 Christophe Guinet 1
2 Lab-STICC_ENSTAB_CID_TOMS
Lab-STICC - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance
3 Pôle STIC_AP
ENSTA Bretagne - École Nationale Supérieure de Techniques Avancées Bretagne
Abstract : Measuring physiological data in free-ranging marine mammals remains challenging, owing to their far-ranging foraging habitat. Yet, it is important to understand how these divers recover from effort expended underwater, as marine mammals can perform deep and recurrent dives. Among them, southern elephant seals (Mirounga leonina) are one of the most extreme divers, diving continuously at great depth and for long duration while travelling over large distances within the Southern Ocean. To determine how they manage post-dive recovery, we deployed hydrophones on four post-breeding female southern elephant seals. Cardiac data were extracted from sound recordings when the animal was at the surface breathing. Mean heart rate at the surface was 102.4±4.9 beats.min(-1) and seals spent on average 121±20 s breathing. During these surface intervals, the instantaneous heart rate is increasing with time. Elephant seals are supposed to drastically slow their heart rate (bradycardia) while they are deep underwater, and increase it (tachycardia) during the ascent towards the surface. Our finding suggests that tachycardia continues while the animal stays breathing at the surface. Also, the measured mean heart rate at the surface was unrelated to the duration and swimming effort of the dive prior to the surface interval. Recovery (at the surface) after physical effort (underwater) appears to be related to the overall number of heart beats performed at the surface, and therefore total surface duration. Southern elephant seals recover from dives by adjusting the time spent at the surface rather than their heart rate
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https://hal.archives-ouvertes.fr/hal-01499321
Contributeur : Martine Lacalle <>
Soumis le : vendredi 31 mars 2017 - 11:22:27
Dernière modification le : vendredi 14 août 2020 - 03:01:14

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Louise Day, Joffrey Jouma'A, Julien Bonnel, Christophe Guinet. Acoustic measurements of post-dive cardiac responses in southern elephant seals ( Mirounga leonina ) during surfacing at sea. Journal of Experimental Biology, Cambridge University Press, 2017, 220, pp.1626-1633. ⟨10.1242/jeb.146928⟩. ⟨hal-01499321⟩

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