First odyssey beneath the sea ice of juvenile emperor penguins in East Antarctica

• Published in: Marine Ecology Progress Series
• Main Authors: Labrousse, Sara, Orgeret, Florian, Solow, Andrew R., Barbraud, Christophe, Sallée, Jean-Baptiste, Bost, Charles-André, Weimerskirch, Henri, Jenouvrier, Stéphanie
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Woods Hole Oceanographic Institution (WHOI), Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: Sea ice; Oceanographic conditions; Antarctic ecology; Juvenile behavior; Thermocline; Diving behavior; Foraging ecology; Emperor penguins; Aptenodytes forsteri; [SDV.BA.ZV]Life Sciences [q-bio]/Animal biology/Vertebrate Zoology; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Antarc*; Antarctic; Antarctica; East Antarctica
• Online Access: https://hal.sorbonne-universite.fr/hal-02024390; https://hal.sorbonne-universite.fr/hal-02024390/document; https://hal.sorbonne-universite.fr/hal-02024390/file/m609p001.pdf; https://doi.org/10.3354/meps12831

International audience Adult emperor penguins Aptenodytes forsteri breed on fast ice and forage within sea ice in winter. However, it remains unknown whether juveniles exhibit similar foraging behavior during their early life at-sea movements, and how it links with the oceanographic conditions. We investigated the first at-sea odyssey of 15 juvenile emperor penguins from Terre Adélie in 2013-2014. The average tracking duration was 167 ± 110 d SD (range 86-344 d). After departing the colony in December/January, the juveniles traveled north up to 53.76°S before heading south in April/May to forage within the sea ice. The juveniles spent 49 ± 14% of their total recorded trips (n = 12) in the sea ice, over both the continental slope and deep ocean regions. The penguins dived primarily during daylight. Within sea ice, the juveniles performed both shallow and deep dives, with the proportion of each varying seasonally. The switch to primarily deep dives in the autumn and winter within sea ice may be a consequence of (1) a seasonal change in the krill distribution from surface to deep waters and/or (2) the presence of macrozooplankton at depth due to a reduced/absent diel migration. Furthermore, we showed for the first time that the diving behavior of juveniles was associated with the mixed layer depth. We suggest they feed on mesopelagic prey aggregating near the thermocline. This study provides insight into an important, but poorly understood, part of the emperor penguin life cycle, essential to predict their response to future climate change.