Ontogenetic dietary changes in male South American fur seals Arctocephalus australis in Patagonia

Marine Ecology Progress Series

Lisette Zenteno¹  Néstor A. García¹  Luis Cardona¹  Enrique A. Crespo¹  Damián G. Vales¹ 

关键词: Foraging ecology;    Pinniped;    Arctocephalus australis;    Ontogenetic dietary change;    Stable isotope analysis;    δ15N;    δ13C;    Patagonia;   

DOI  :  10.3354/meps11214

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: This study assessed ontogenetic dietary changes in male South American fur seals Arctocephalus australis in northern and central Patagonia (Argentina) using stable isotope ratios (δ¹⁵N and δ¹³C) in vibrissae and bones. Sucking pups were characterised by higher δ¹⁵N values and lower δ¹³C values than older specimens. Weaning was associated with a marked drop of δ¹⁵N values, both in bone and vibrissae. Such a drop was inconsistent with the consumption of local prey and may reveal movement to distant foraging grounds or physiological changes associated with either fasting or rapid growth. Stable isotope ratios indicated that juveniles fed more pelagically than subadults and adults, but that there were no major differences between the 2 latter age categories. As subadults and adults are rather similar in body mass and are much larger than juveniles, body mass may play a role in the ontogenetic dietary changes reported. Nevertheless, demersal benthic prey were always scarce in the diet of male fur seals, which relied primarily on Argentine shortfin squid and small pelagic fish throughout life, though adults also consumed large amounts of decapod crustaceans available at shallow depths. Vibrissae did not reveal regular oscillations of δ¹⁵N or δ¹³C, except in 1 individual. Thus, male fur seals from northern and central Patagonia do not appear to migrate regularly between isotopically distinct areas, although nomadic displacements cannot be ruled out.

【 授权许可】

Unknown