Stable carbon and nitrogen isotope variations in canine dentine growth layers of Kerguelen southern elephant seals

Marine Ecology Progress Series

Ilham Bentaleb¹  C#xe9line Martin¹  Christophe Guinet¹  St#xe9phanie Steelandt¹ 

关键词: Mirounga leonina;    Dentine δ13C and δ15N;    Trophic level;    Foraging habitat;   

DOI  :  10.3354/meps09331

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: Foraging behaviour of mammals, namely the change in distribution and trophic levels from juvenile stage to adulthood, can be investigated by measuring δ¹³C and δ¹⁵N stable isotopes for layers deposited in a growing tooth. For the first time, we describe geographic differences in the ontogeny of foraging strategies and in the niche partitioning process according to sex and age of a highly sexually dimorphic species: the southern elephant seal Mirounga leonina. Canines from 8 males and 6 females were analysed for δ¹³C and δ¹⁵N stable isotope signatures. To assess intra-individual variability, instead of analysing collagen we analysed the bulk dentine within each of the 4 growth layers deposited annually. The δ¹³C signature revealed that, in individuals of 1 to 4 yr of age, teeth of both males and females exhibited large intra-individual variation in δ¹³C, suggesting that juveniles were foraging over a broad range of marine habitats encompassing both sub-Antarctic and Antarctic waters. Four out of the 6 teeth taken from females were collected on individuals younger than 4 yr, preventing investigation of longer-term changes. A δ¹³C pattern emerged for males older than 4 yr: individuals became resident to either a sub-Antarctic (–17‰) or an Antarctic (–20‰, both values reported as deviations from the Vienna PeeDee Belemnite standard) foraging habitat, with a decrease in intra-individual variability. Up to the age of 4 yr, juvenile males were at a slightly higher trophic level than juvenile females, but by the age of 4 yr, while their δ¹³C signature revealed that they were faithful to their foraging habitat, males exhibited a significant increase in their trophic levels, as shown by their δ¹⁵N signature.

【 授权许可】

Unknown