Elephant seal foraging success is enhanced in Antarctic coastal polynyas

• Published in: Proceedings of the Royal Society B: Biological Sciences
• Main Authors: Arce, Fernando, Hindell, Mark, Mcmahon, Clive, Wotherspoon, Simon, Guinet, Christophe, Harcourt, Robert, Bestley, Sophie
• Other Authors: Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia, Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Department of Biological Sciences Australia, Macquarie University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Mirounga leonina; body condition; drift rates; Southern Ocean; post-polynyas; foraging behaviour; [SDE]Environmental Sciences; Antarctic; The Antarctic; Antarc*; Elephant Seal; Elephant Seals; Southern Elephant Seals
• Online Access: https://hal.science/hal-03563073; https://doi.org/10.1098/rspb.2021.2452

International audience Antarctic polynyas are persistent open water areas which enable early and large seasonal phytoplankton blooms. This high primary productivity, boosted by iron supply from coastal glaciers, attracts organisms from all trophic levels to form a rich and diverse community. How the ecological benefit of polynya productivity is translated to the highest trophic levels remains poorly resolved. We studied 119 southern elephant seals feeding over the Antarctic shelf and demonstrated that: (i) 96% of seals foraging here used polynyas, with individuals spending on average 62% of their time there; (ii) the seals exhibited more area-restricted search behaviour when in polynyas; and (iii) these seals gained more energy (indicated by increased buoyancy from greater fat stores) when inside polynyas. This higher-quality foraging existed even when ice was not present in the study area, indicating that these are important and predictable foraging grounds year-round. Despite these energetic advantages from using polynyas, not all the seals used them extensively. Factors other than food supply may influence an individual's choice in their use of feeding grounds, such as exposure to predation or the probability of being able to return to distant sub-Antarctic breeding sites.