Abstract
AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 25:1-6 (2016) - DOI: https://doi.org/10.3354/ab00652 NOTE Lipid extraction in stable isotope analyses of juvenile sea turtle skin and muscle Thaisa F. Bergamo1,2, Silvina Botta2,3,*, Margareth Copertino1,2 1Laboratório de Ecologia Vegetal Costeira, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, CP 474, Rio Grande, RS 96203-900, Brazil 2Programa de Pós-Graduação em Oceanografia Biológica, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, CP 474, Rio Grande, RS 96203-900, Brazil 3Laboratório de Ecologia e Conservação da Megafauna Marinha, Universidade Federal do Rio Grande - FURG, CP 474, Rio Grande, RS 96203-900, Brazil *Corresponding author: silbotta@gmail.com ABSTRACT: Studies involving various aspects of the biology and ecology of sea turtles have successfully applied stable isotope analysis. In many of these studies, the chemical extraction of 13C-depleted lipids of sea turtle tissues has been used as a standard protocol, often without testing whether the time-consuming lipid removal is required. Furthermore, this chemical procedure may unpredictably modify δ15N values, probably due to the loss of proteins associated with lipid structures, thus reinforcing the need for testing the isotopic consequence of the chemical removal of lipids. This study aimed to evaluate the effects of lipid extraction on skin and muscle C and N isotopic values of juvenile green turtles Chelonia mydas. We analyzed paired δ13C and δ15N values from lipid-extracted and non-lipid-extracted samples of skin and muscle of 15 juvenile green turtles. Lipid extraction was performed using a mixture of chloroform and methanol. A significant increase was found in δ13C values after lipid extraction for muscle (~0.5‰), but not for skin. C:N ratios were not correlated with the change in δ13C values in either tissue. δ15N values were not affected by lipid extraction in either tissue. The difference found in δ13C values between control and lipid-extracted muscle samples may be biologically significant. On the other hand, the lipid extraction of skin samples does not appear to be necessary in the case of juvenile green turtles. This procedure needs to be tested in green turtles in other life stages. KEY WORDS: Green turtle · Chelonia mydas · Stable isotope analysis · Carbon · Nitrogen · δ13C · δ15N · Lipid extraction Full text in pdf format NextCite this article as: Bergamo TF, Botta S, Copertino M (2016) Lipid extraction in stable isotope analyses of juvenile sea turtle skin and muscle. Aquat Biol 25:1-6. https://doi.org/10.3354/ab00652 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 25. Online publication date: May 25, 2016 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2016 Inter-Research.
Highlights
Stable isotope analysis (SIA) of animal tissue carbon (δ13C values) and nitrogen (δ15N values) has been largely used to study the trophic ecology and habitat use of several taxa, including marine megafauna
Testing the effects of lipid removal on both δ13C and δ15N values is highly relevant before applying SIA to address questions about diet and trophic ecology
Mean δ13C differences between control and lipid-extracted samples (Δδ13C) was 0.51 ‰. This difference was mainly driven by 3 samples that showed an increase of > 0.5 ‰ after lipid extraction, with all other samples being less modified by the treatment (i.e. Δδ13C < 0.5 ‰; Fig. 1)
Summary
Stable isotope analysis (SIA) of animal tissue carbon (δ13C values) and nitrogen (δ15N values) has been largely used to study the trophic ecology and habitat use of several taxa, including marine megafauna (e.g. seabirds, Cherel et al 2005; sea turtles, Arthur et al 2008; sharks, Carlisle et al 2015; marine mammals, Drago et al 2015). Due to differences in the biochemical pathways during synthesis, lipids may be depleted in 13C relative to other major constituents, such as proteins (DeNiro & Epstein 1977). Such differences among protein and lipid metabolism (Martínez del Rio et al 2009) can bias the interpretation of stable isotope values and result in misleading diet reconstructions, especially when based on tissues with a significant amount of fat (Ricca et al 2007).
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