Carbon and nitrogen isotope fractionation of amino acids in an avian marine predator, the gentoo penguin (Pygoscelis papua)
McMahon, Kelton W.
Polito, Michael J.
McCarthy, Matthew D.
Thorrold, Simon R.
MetadataShow full item record
KeywordAmino acid; Avian; Compound-specific stable isotope analysis; Diet; Fractionation; Penguin; Trophic position
Compound-specific stable isotope analysis (CSIA) of amino acids (AA) has rapidly become a powerful tool in studies of food web architecture, resource use, and biogeochemical cycling. However, applications to avian ecology have been limited because no controlled studies have examined the patterns in AA isotope fractionation in birds. We conducted a controlled CSIA feeding experiment on an avian species, the gentoo penguin (Pygoscelis papua), to examine patterns in individual AA carbon and nitrogen stable isotope fractionation between diet (D) and consumer (C) (Δ13CC-D and Δ15NC-D, respectively). We found that essential AA δ13C values and source AA δ15N values in feathers showed minimal trophic fractionation between diet and consumer, providing independent but complimentary archival proxies for primary producers and nitrogen sources respectively, at the base of food webs supporting penguins. Variations in nonessential AA Δ13CC-D values reflected differences in macromolecule sources used for biosynthesis (e.g., protein vs. lipids) and provided a metric to assess resource utilization. The avian-specific nitrogen trophic discrimination factor (TDFGlu-Phe = 3.5 ± 0.4‰) that we calculated from the difference in trophic fractionation (Δ15NC-D) of glutamic acid and phenylalanine was significantly lower than the conventional literature value of 7.6‰. Trophic positions of five species of wild penguins calculated using a multi-TDFGlu-Phe equation with the avian-specific TDFGlu-Phe value from our experiment provided estimates that were more ecologically realistic than estimates using a single TDFGlu-Phe of 7.6‰ from the previous literature. Our results provide a quantitative, mechanistic framework for the use of CSIA in nonlethal, archival feathers to study the movement and foraging ecology of avian consumers.
© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ecology and Evolution 5 (2015): 1278–1290, doi:10.1002/ece3.1437.
Suggested CitationArticle: McMahon, Kelton W., Polito, Michael J., Abel, Stephanie, McCarthy, Matthew D., Thorrold, Simon R., "Carbon and nitrogen isotope fractionation of amino acids in an avian marine predator, the gentoo penguin (Pygoscelis papua)", Ecology and Evolution 5 (2015): 1278–1290, DOI:10.1002/ece3.1437, https://hdl.handle.net/1912/7215
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Stable isotope analyses of feather amino acids identify penguin migration strategies at ocean basin scales Polito, Michael J.; Hinke, Jefferson T.; Hart, Tom; Santos, Mercedes; Houghton, Leah A.; Thorrold, Simon R. (2017-07)Identifying the at-sea distribution of wide ranging 20 marine predators is critical to understanding their ecology. Advances in electronic tracking devices and intrinsic biogeochemical markers have greatly improved our ...
Degens, Egon T.; Hunt, John M. (Woods Hole Oceanographic Institution, 1968-02)In February-March 1965, a series of piston cores were taken aboard ATLANTIS II off the coast of Arabia, Pakistan, and India (Figure 1) in water depths of about 3,000 meters. The principal objectives of this program were ...
Observations of Li isotopic variations in the Trinity Ophiolite : evidence for isotopic fractionation by diffusion during mantle melting Lundstrom, Craig C.; Chaussidon, Marc; Hsui, Albert T.; Kelemen, Peter B.; Zimmerman, Mark (2004-08-10)The Trinity peridotite (northern CA) contains numerous lithologic sequences consisting of dunite to harzburgite to spinel lherzolite to plagioclase lherzolite. Previous workers have documented geochemical gradients in these ...