[MARMAM] New publication on lipid extraction and acidification in stable isotopes of ziphiid bones

Carol Tatsch carol.c.tatsch at gmail.com
Wed Jan 27 19:27:37 PST 2016

Dear MARMAM subscribers,

My colleagues and I are pleased to announce the publication of our research

Tatsch, A. C. C., Secchi, E. R., & Botta, S. (2016). Effects of
acidification, lipid removal and mathematical normalization on carbon and
nitrogen stable isotope compositions in beaked whale (Ziphiidae) bone. *Rapid
Communications in Mass Spectrometry, 30*, 460–466.

RATIONALE: The analysis of stable isotopes in tissues such as teeth and
bones has been used to study long-term trophic ecology and habitat use in
marine mammals. However, carbon isotope ratios (δ13C values) can be altered
by the presence of 12C-rich lipids and carbonates. Lipid extraction and
acidification are common treatments used to remove these compounds. The
impact of lipids and carbonates on carbon and nitrogen isotope ratios (δ15N
values), however, varies among tissues and/or species, requiring
taxon-specific protocols to be developed. METHODS: The effects of lipid
extraction and acidification and their interaction on carbon and nitrogen
isotope values were studied for beaked whale (Ziphiidae) bone samples. δ13C
and δ15N values were determined in quadruplicate samples: control,
lipid-extracted, acidified and lipid-extracted followed by acidification.
Samples were analyzed by means of elemental analysis isotope ratio mass
spectrometry. Furthermore, the efficiency of five mathematical models
developed for estimating lipid-normalized δ13C values from untreated δ13C
values was tested. RESULTS: Significant increases in δ13C values were
observed after lipid extraction. No significant changes in δ13C values were
found in acidified samples. An interaction between both treatments was
demonstrated for δ13C but not for δ15N values. No change was observed in δ15N
values for lipid-extracted and/or acidified samples. Although all tested
models presented good predictive power to estimate lipid-free δ13C values,
linear models performed best. CONCLUSIONS: Given the observed changes in δ13C
values after lipid extraction, we recommend *a priori* lipid extraction or *a
posteriori* lipid normalization, through simple linear models, for beaked
whale bones. Furthermore, acidification seems to be an unnecessary step
before stable isotope analysis, at least for bone samples of ziphiids.

The article is available from the publisher's website (
http://doi.org/10.1002/rcm.7457) or by request at carol.c.tatsch at gmail.com

Best regards,

Ana Carolina Tatsch

MSc. Ana Carolina Corrêa Tatsch
Programa de Pós-graduação em Oceanografia Biológica - PPGOB
Laboratório de Ecologia e Conservação da Megafauna Marinha- EcoMega
Instituto de Oceanografia - IO
Universidade Federal do Rio Grande - FURG
Rio Grande/RS - Brasil
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