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Master Thesis

Évaluation des performances d'acquisition et des types de proies consommées par les femelles éléphants de mer de la Péninsule Valdés et des Îles Kerguelen

Abstract : The distribution and abundance of marine resources are subject to variations in environmental parameters. The ability of marine predators, such as the southern elephant seals (SES), Mirounga leonina, to forage efficiently can determine their net energy gain. In this study, 16 SES females from the Kerguelen Islands (KER) and 12 SES females from the Valdes Peninsula (VP) were equipped with time-depth recorders (TDRs) and accelerometers to compare the foraging performance and types of prey consumed by these two geographically distant colonies. Data from the accelerometers allow for the number of prey capture attempts (PCAs) and the body condition of the animals to be estimated from the drift rate. The following behavioural parameters were studied as a function of the locations, the temperature at 200 m, and the difference in light intensity between the surface and 150 m, using linear mixed models: 1) the depth of the dive, 2) the duration of the bottom phase, 3) the swimming effort in the bottom phase and 4) the number of PCAs in the bottom phase. The results obtained do not show any difference in dive depth, bottom phase duration, or bottom phase swimming effort between the two populations. However, KER individuals have three times the number of PCAs than VP individuals. In addition, KER females leave for the ocean in poorer physical condition than VP females and improve their body condition slower than VP females. These results suggest that the prey caught by these two populations of SES are different. Future studies should aim to more accurately identify the prey consumed by elephant seals and assess their net foraging success, in order to compare the foraging performance of these two colonies.
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Master Thesis
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https://dumas.ccsd.cnrs.fr/dumas-03038305
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Submitted on : Thursday, December 3, 2020 - 2:09:37 PM
Last modification on : Friday, February 19, 2021 - 3:29:30 AM
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Nolwenn Dameron. Évaluation des performances d'acquisition et des types de proies consommées par les femelles éléphants de mer de la Péninsule Valdés et des Îles Kerguelen. Sciences de l'environnement. 2020. ⟨dumas-03038305⟩

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