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MEPS 614:199-207 (2019)  -  DOI: https://doi.org/10.3354/meps12913

Use of 15N-enriched glycine to estimate vibrissa growth in free-ranging northern elephant seals Mirounga angustirostris

David Aurioles-Gamboa1,*, Seth D. Newsome2, Jason L. Hassrick3, Tatiana Acosta-Pachón4, Félix Aurioles-Rodríguez5, Daniel P. Costa6

1Facultad de Ingeniería Ambiental, Universidad Popular Autónoma del Estado de Puebla, Puebla 72410, México
2Biology Department, University of New Mexico, Albuquerque, New Mexico 87131, USA
3ICF Fish and Aquatic Science, 201 Mission Street, Suite 1500, San Francisco, California 94105, USA
4Departamento Académico de Ciencias Marinas y Costeras. Universidad Autónoma de Baja California Sur, La Paz, Baja California Sur 23080, México
5División de Ciencias Naturales y Exactas, Universidad de Guanajuato, 36050 Guanajuato, México
6Ecology and Evolutionary Biology Department, University of California Santa Cruz, Santa Cruz, California 95064, USA
*Corresponding author:

ABSTRACT: The stable isotope composition of continuously growing but metabolically inert tissues remains unaltered after they are synthesized, providing insights on seasonal and inter-annual variation in the ecology of individuals. In pinnipeds, isotope analysis of sub-sampled vibrissae can provide a longitudinal record of movement, diet, and even physiological state at the individual level. To reliably apply this approach, however, taxon-specific vibrissa growth needs to be estimated, especially for species with complicated annual life cycles that undergo periods of active foraging interspersed with reproduction and/or molting associated with fasting. Here, we intravenously injected 15N-enriched glycine to estimate vibrissa growth in 8 free-ranging adult female northern elephant seals during their (shorter) post-breeding and (longer) post-molting foraging trips; all animals were instrumented with satellite tags to track movements and vibrissae were collected when the animals returned to land. We found a significant positive relationship between the maximum δ15N values, representing 15N-glycine injections, and the distance between the origin of the spike and the root of the vibrissa. The δ15N spikes that occurred closest to the root were narrower and had lower δ15N values than those that occurred closer to the tip of the vibrissa, suggesting differential velocities of 15N-glycine absorption and vibrissa growth. A derived von Bertalanffy model yielded mean (±SD) growth of 0.015 ± 0.006 d-1, similar to that previously reported for a single captive northern elephant seal. Vibrissa length is an important consideration for accurately interpreting isotope-based ecological and physiological histories given the non-continuous growth observed in our study.


KEY WORDS: Northern elephant seal · Vibrissae growth · 15N-enriched glycine


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Cite this article as: Aurioles-Gamboa D, Newsome SD, Hassrick JL, Acosta-Pachón T, Aurioles-Rodríguez F, Costa DP (2019) Use of 15N-enriched glycine to estimate vibrissa growth in free-ranging northern elephant seals Mirounga angustirostris. Mar Ecol Prog Ser 614:199-207. https://doi.org/10.3354/meps12913

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