Physical changes recorded by a deep diving seal on the Patagonian slope drive large ecological changes

• Published in: Journal of Marine Systems
• Main Authors: Aubone, Nicolas, Saraceno, M., Torres Alberto, M.L., Campagna, J., Le Ster, Loïc, Picard, Baptiste, Hindell, Mark, Campagna, C., Guinet, Chirstophe
• Other Authors: Centro de Investigaciones del Mar y la Atmósfera (CIMA/CONICET-UBA), Instituto de Investigaciones Marinas y Costeras (IIMyC/UNMdP-CONICET), Centro para el Estudio de Sistemas Marinos (CESIMAR/CENPAT-CONICET) (CESIMAR), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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), Institute for Marine and Antarctic Studies and Centre for Marine Socioecology, University of Tasmania Hobart, Australia (UTAS), Wildlife Conservation Society Argentina, Ciudad Autónoma de Buenos Aires
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Southwestern Atlantic Ocean; Patagonian shelf slope; Elephant seals; Mirounga leonina; Malvinas current; [SDE]Environmental Sciences; Elephant Seal; Elephant Seals; Southern Elephant Seal
• Online Access: https://hal.science/hal-03295922; https://hal.science/hal-03295922/document; https://hal.science/hal-03295922/file/S0924796321001081.pdf; https://doi.org/10.1016/j.jmarsys.2021.103612

International audience The Patagonian slope is the region where Subantarctic waters and bathymetry give raise to physical and ecological processes that support a rich biodiversity and a large-scale industrial fisheries. Unique among the species that depend on this region is the deep diving southern elephant seal, Mirounga leonina. We report here on changes in the foraging behavior of a female seal explained by the combined effect of a cold and high salinity water mass and a decrease in surface chlorophyll-a concentration. Behavioral and oceanographic data from about 5000 profiles of temperature, conductivity, pressure, light and prey encounters were collected within an area ranging 59.5–61°W and 46–47.5°S, at depths of 300–700 m, on the Patagonian slope, during November–December 2018. A decrease in temperature (0.15 °C) and an increase in salinity (0.03) was found below the mixed layer, during December. Light data revealed a significant increase of irradiance in December (almost reaching the ocean bottom) associated with a decrease of chlorophyll-a in the upper levels. Concomitantly, the seal had a different diving behavior in December, foraging near the surface at night and close to the bottom during daylight hours. Also, the seal doubled the prey capture attempts in December compared to November. This study reveals the importance of ocean physical properties on seal's diving and foraging behavior, and how this changes, although small, can impact on seals diet and body composition during their post-breeding trips.