Sardenne Fany, Ménard Frédéric, Degroote M., Fouche Edwin, Guillou G., Lebreton B., Hollanda S. J., Bodin Nathalie. (2015). Methods of lipid-normalization for multi-tissue stable isotope analyses in tropical tuna. Rapid Communications in Mass Spectrometry, 29 (13), p. 1253-1267. ISSN 0951-4198.
Titre du document
Methods of lipid-normalization for multi-tissue stable isotope analyses in tropical tuna
Sardenne Fany, Ménard Frédéric, Degroote M., Fouche Edwin, Guillou G., Lebreton B., Hollanda S. J., Bodin Nathalie
Source
Rapid Communications in Mass Spectrometry, 2015,
29 (13), p. 1253-1267 ISSN 0951-4198
RATIONALE: The bias associated with lipid contents in fish tissues is a recalcitrant topic for trophic studies using stable isotopes. Lipids are depleted in the heavy carbon isotope (C-13) and the lipid content varies considerably among species, tissues and in both time and space. We have applied and assessed different correction methods for tropical tuna tissues. METHODS: We tested two types of normalization methods to deal with variable lipid content in liver, gonads, and white and red muscles of yellowfin, bigeye and skipjack tuna: a chemical extraction using dichloromethane and a mathematical correction based on three modeling approaches (linear, non-linear and mass balance models). We measured isotopic ratios of bulk and lipid-free tissues and assessed the predictive ability of the correction models with the lipid-free measurements. The parameters of the models were estimated from our dataset and from results from published studies on other species. RESULTS: Comparison between bulk, lipid-free and lipid-corrected isotopic ratios demonstrated that (1) chemical extraction using dichloromethane did not affect delta N-15 values; (2) the change in delta C-13 values after extraction was tissue-specific; (3) lipid-normalization models using published parameter estimates failed to predict lipid-corrected delta C-13 values; and (4) linear and non-linear models using parameters estimated for each tissue from our dataset provided accurate delta C-13 predictions for all tissues, and mass balance model for white muscle only. CONCLUSIONS: Models using published estimates for parameters from other species cannot be used. Based on a range of lipid content that do not exceed 45%, we recommend the linear model to correct the bulk delta C-13 values in the investigated tissues but the parameters have to be estimated from a proportion of the original data for which chemical extraction is required and the isotopic values of bulk and lipid-free tissues are measured.
Plan de classement
Sciences fondamentales / Techniques d'analyse et de recherche [020]
;
Ressources halieutiques [040]
