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Lipid extraction has little effect on the δ15N of aquatic consumers

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Published
  • Travis Ingram
  • Blake Matthews
  • Christopher Harrod
  • Tom Stephens
  • Jonathan Grey
  • Russell Markel
  • Asit Mazumder
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<mark>Journal publication date</mark>10/2007
<mark>Journal</mark>Limnology and Oceanography
Issue number10
Volume5
Number of pages5
Pages (from-to)338-342
Publication StatusPublished
<mark>Original language</mark>English

Abstract

Proper application of stable isotopes (e.g., δ15N and δ13C) to food web analysis requires an understanding of all nondietary factors that contribute to isotopic variability. Lipid extraction is often used during stable isotope analysis (SIA), because synthesized lipids have a low δ13C and can mask the δ13C of a consumer's diet. Recent studies indicate that lipid extraction intended to adjust δ13C may also cause shifts in δ15N, but the magnitude of and reasons for the shift are highly uncertain. We examined a large data set (n = 854) for effects of lipid extraction (using Bligh and Dyer's [1959] chloroform-methanol solvent mixtures) on the δ15N of aquatic consumers. We found no effect of chemically extracting lipids on the δ15N of whole zooplankton, unionid mussels, and fish liver samples, and found a small increase in fish muscle δ15N of ~0.4‰. We also detected a negative relationship between the shift in δ15N following extraction and the C:N ratio in muscle tissue, suggesting that effects of extraction were greater for tissue with lower lipid content. As long as appropriate techniques such as those from Bligh and Dyer (1959) are used, effects of lipid extraction on δ15N of aquatic consumers need not be a major consideration in the SIA of food webs.