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Marine Ecology Progress Series

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MEPS 523:243-253 (2015)  -  DOI:

Fine-scale whisker growth measurements can reveal temporal foraging patterns from stable isotope signatures

Roxanne S. Beltran1,4,*, Megan Connolly Sadou2, Richard Condit3, Sarah H. Peterson1, Colleen Reichmuth2, Daniel P. Costa1

1Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
2Institute of Marine Sciences, Long Marine Laboratory, Santa Cruz, CA 95060, USA
3Smithsonian Tropical Research Institute, Balboa, Panama City, 0843-03092, Panama
4Present address: Department of Biological Sciences, University of Alaska, Anchorage, AK 99508, USA
*Corresponding author:

ABSTRACT: Stable isotope analysis of slow-growing, metabolically inert tissues is a common method for investigating foraging ecology in migratory animals, as direct observations of feeding are often not possible. Using tissue growth dynamics to interpret foraging timelines can maximize the utility of foraging data; however, applying inappropriate growth models is problematic, and high-resolution growth measurements are seldom made. We used photogrammetry to repeatedly measure the length of whiskers in 93 follicles over 670 d in a trained, captive northern elephant seal Mirounga angustirostris. We developed and optimized a follicle-specific growth model to describe the 18000 whisker length measurements. Whiskers from the captive seal exhibited asymptotic growth that was described by the von Bertalanffy growth function. Applying the growth model to serially sampled whiskers from 4 free-ranging adult female northern elephant seals resulted in alignment of peaks in δ15N along the length of whiskers with the breeding haul-out period, when seals are not feeding. Our study provides a high-resolution whisker growth model and is the first to use whisker growth dynamics to improve temporal interpretation of isotopic ratios.

KEY WORDS: Vibrissae · Whisker · Asymptotic growth rate · Stable isotope · Seal

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Cite this article as: Beltran RS, Connolly Sadou M, Condit R, Peterson S, Reichmuth C, Costa DP (2015) Fine-scale whisker growth measurements can reveal temporal foraging patterns from stable isotope signatures. Mar Ecol Prog Ser 523:243-253.

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