MEPS 493:1-8 (2013)  -  DOI: https://doi.org/10.3354/meps10560

FEATURE ARTICLE
Sample acidification significantly alters stable isotope ratios of sulfur in aquatic plants and animals

Rod M. Connolly1,*, Thomas A. Schlacher2

1Australian Rivers Institute - Coast and Estuaries, and School of Environment, Gold Coast Campus, Griffith University, Queensland 4222, Australia
2Faculty of Science, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia

ABSTRACT: Sulfur stable isotopes are increasingly being used as tracers of material processing in studies of both modern and historical food webs. Preparation of plant and animal material for isotope analysis routinely includes steps that remove inorganic material not normally assimilated by consumers. Whereas acidification of samples is known to assist with this for some elements (carbon), it can produce unwanted effects for others (nitrogen). Here we tested the effects of acidification on sulfur isotopes by comparing isotope ratios of paired acidified and non-acidified samples of seagrass, epiphytic algae growing on seagrass and animal consumers (3 types of crustaceans: amphipods, copepods and isopods). Acid treatment resulted in significant losses of elemental sulfur from the tissues and changes in sulfur isotope ratios of samples. The artificial depletion of the heavy sulfur isotope decreased sulfur isotope ratios by 2.6‰ on average, and by as much as 7.0‰ in individual samples. Acidification of samples prior to sulfur isotope analysis results in invalid ratios and should not be used.


KEY WORDS: Acid digestion · Amino acids · Carbonate · DMSP · Seagrass · Stable isotope analysis


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Cite this article as: Connolly RM, Schlacher TA (2013) Sample acidification significantly alters stable isotope ratios of sulfur in aquatic plants and animals. Mar Ecol Prog Ser 493:1-8. https://doi.org/10.3354/meps10560

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