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How to account for the lipid effect on carbon stable‐isotope ratio (δ 13 C): sample treatment effects and model bias
Author(s) -
Mintenbeck K.,
Brey T.,
Jacob U.,
Knust R.,
Struck U.
Publication year - 2008
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.2007.01754.x
Subject(s) - normalization (sociology) , biology , trophic level , stable isotope ratio , isotopes of carbon , lipid metabolism , biochemistry , ecology , physics , quantum mechanics , sociology , anthropology , total organic carbon
This study investigated the impact of lipid extraction, CaCO 3 removal and of both treatments combined on fish tissue δ 13 C, δ 15 N and C:N ratio. Furthermore, the suitability of empirical δ 13 C lipid normalization and correction models was examined. δ 15 N was affected by lipid extraction (increase of up to 1·65‰) and by the combination of both treatments, while acidification alone showed no effect. The observed shift in δ 15 N represents a significant bias in trophic level estimates, i.e. lipid‐extracted samples are not suitable for δ 15 N analysis. C:N and δ 13 C were significantly affected by lipid extraction, proportional to initial tissue lipid content. For both variables, rates of change with lipid content (ΔC:N and Δδ 13 C) were species specific. All tested lipid normalization and correction models produced biased estimates of fish tissue δ 13 C, probably due to a non‐representative database and incorrect assumptions and generalizations the models were based on. Improved models need a priori more extensive and detailed studies of the relationships between lipid content, C:N and δ 13 C, as well as of the underlying biochemical processes.