Effects of lipid extraction on stable carbon and nitrogen isotope analyses of fish tissues: potential consequences for food web studies |
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| Authors: | M A Sotiropoulos W M Tonn L I Wassenaar |
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| Institution: | Department of Biological Sciences, University of Alberta, Edmonton, Alberta;, National Water Research Institute, Environment Canada, Saskatoon, Saskatchewan, Canada;, Present address: North/South Consultants, Inc., 83 Scurfield Crescent, Winnipeg, Manitoba R3Y 1G4, Canada |
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| Abstract: | Abstract – We examined whether solvent-based lipid extractions, commonly used for stable isotope analysis (SIA) of biota, alters δ 15N or δ 13C values of fish muscle tissue or whole juvenile fish. Lipid extraction from muscle tissue led to only small (<1‰) isotope shifts in δ 13C and δ 15N values. By contrast, ecologically significant shifts (+3.4‰ for δ 13C and +2.8‰ for δ 15N) were observed for whole juvenile fish. Sample variance was not affected by lipid extraction. For tissue-specific SIA, two sample aliquots may be required: a lipid-extracted aliquot for stable carbon isotope analysis when differing lipid content among tissues is a concern, and a nonextracted aliquot for δ 15N determination. Whole organism SIA is not recommended because of the mix of tissues having different turnover times; for very small fish, we recommend that fish be eviscerated, decapitated, and skinned to minimise differences with samples of muscle tissue. |
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| Keywords: | stable isotope analysis carbon nitrogen fish lipid extraction |
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