Marine Ecology Progress Series
MEPS is a leading hybrid research journal on all aspects of marine, coastal and estuarine ecology. Priority is given to outstanding research that advances our ecological understanding.
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DOI: https://doi.org/10.3354/meps10560
copiedSample acidification significantly alters stable isotope ratios of sulfur in aquatic plants and animals
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.
KEYWORDS
Acidification of samples prior to sulfur isotope analysis results in invalid ratios and should not be used.
Image: R. Connolly, Symbols: ian.umces.edu/symbols
Stable isotope ratios of sulfur are increasingly being used in the analysis of modern and historical food webs. Preparation of plant and animal material for isotope analysis routinely includes steps (e.g. addition of acid) that remove inorganic material not normally assimilated by consumers. Connolly and Schlacher tested the effects of acidification on sulfur isotopes in seagrass, algae and invertebrate animals. Acid treatment resulted in significant losses of elemental sulfur and changes in sulfur isotope ratios. Acidification of samples prior to sulfur isotope analysis results in invalid ratios and should not be used.
Rod M. Connolly (Co-author)
- Australian Rivers Institute - Coast and Estuaries, and School of Environment, Gold Coast Campus, Griffith University, Queensland 4222, Australia
Thomas A. Schlacher (Co-author)
- Faculty of Science, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia