MEPS 439:295-305 (2011)  -  DOI: https://doi.org/10.3354/meps09331

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.

KEY WORDS: Mirounga leonina · Dentine δ¹³C and δ¹⁵N · Trophic level · Foraging habitat

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Cite this article as: Martin C, Bentaleb I, Steelandt S, Guinet C (2011) Stable carbon and nitrogen isotope variations in canine dentine growth layers of Kerguelen southern elephant seals. Mar Ecol Prog Ser 439:295-305. https://doi.org/10.3354/meps09331 Export citation Share:    Facebook - - linkedIn