The comparative energetics and growth strategies of sympatric Antarctic and subantarctic fur seal pups at Îles Crozet

• Published in: Journal of Experimental Biology
• Main Authors: Arnould, John P.Y., Luque, Sebastian P., Guinet, Christophe, Costa, D.P., Kingston, J., Shaffer, Scott A.
• Other Authors: Department of Zoology, University of Melbourne, Centre d'Études Biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), Department of Biology, Memorial University of Newfoundland = Université Memorial de Terre-Neuve St. John's, Canada (MUN), Department of Ecology and Evolutionary Biology, University of California Santa Cruz (UC Santa Cruz), University of California (UC)-University of California (UC), School of Biological Sciences, Macquarie University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2003
• Subjects: maternal provisioning; metabolic rate; growth strategy; resource partitioning; energetics; weaning; fur seal; Arctocephalus gazella; Arctocephalus tropicalis; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDE.ES]Environmental Sciences/Environmental and Society; [SDE.MCG]Environmental Sciences/Global Changes; Antarctic; Antarc*; Antarctic Fur Seal; Antarctic Fur Seals; Îles Crozet
• Online Access: https://hal.science/hal-00189199; https://doi.org/10.1242/jeb.00703

10 pages International audience The period of maternal dependence is a time during which mammalian infants must optimise both their growth and the development of behavioural skills in order to successfully meet the demands of independent living. The rate and duration of maternal provisioning, postweaning food availability and climatic conditions are all factors likely to influence the growth strategies of infants. While numerous studies have documented differences in growth strategies at high taxonomic levels, few have investigated those of closely related species inhabiting similar environments. The present study examined the body composition, metabolism and indices of physiological development in pups of Antarctic fur seals (Arctocephalus gazella) and subantarctic fur seals (Arctocephalus tropicalis), congeneric species with different weaning ages (4·months and 10·months, respectively), during their overlap in lactation at a sympatric breeding site in the Iles Crozet. Body lipid reserves in pre-moult pups were significantly greater (t28=2.73, P<0.01) in subantarctic (26%) than Antarctic fur seals (22%). Antarctic fur seal pups, however, had significantly higher (t26=3.82, P<0.001) in-air resting metabolic rates (RMR; 17.1±0.6·ml·O2·kg–1·min–1) than subantarctic fur seal pups (14.1±0.5·ml·O2·kg–1·min–1). While in-water standard metabolic rate (SMR; 22.9±2.5·ml·O2·kg–1·min–1) was greater than in-air RMR for Antarctic fur seal pups (t9=2.59, P<0.03), there were no significant differences between in-air RMR and in-water SMR for subantarctic fur seal pups (t12=0.82, P>0.4), although this is unlikely to reflect a greater ability for pre-moult pups of the latter species to thermoregulate in water. Pup daily energy expenditure was also significantly greater (t27=2.36, P<0.03) in Antarctic fur seals (638±33·kJ·kg–1·day–1) than in subantarctic fur seals (533±33·kJ·kg–1·day–1), which corroborates observations that pups of the former species spend considerably more time actively learning to swim and ...