Controlling for anthropogenically induced atmospheric variation in stable carbon isotope studies

Eric S. Long, Richard A. Sweitzer, Duane R. Diefenbach, Merav Ben-David

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Increased use of stable isotope analysis to examine food-web dynamics, migration, transfer of nutrients, and behavior will likely result in expansion of stable isotope studies investigating human-induced global changes. Recent elevation of atmospheric CO2 concentration, related primarily to fossil fuel combustion, has reduced atmospheric CO2 δ13C (13C/12C), and this change in isotopic baseline has, in turn, reduced plant and animal tissue δ13C of terrestrial and aquatic organisms. Such depletion in CO2 δ13C and its effects on tissue δ13C may introduce bias into δ13C investigations, and if this variation is not controlled, may confound interpretation of results obtained from tissue samples collected over a temporal span. To control for this source of variation, we used a high-precision record of atmospheric CO2 δ13C from ice cores and direct atmospheric measurements to model modern change in CO2 δ13C. From this model, we estimated a correction factor that controls for atmospheric change; this correction reduces bias associated with changes in atmospheric isotopic baseline and facilitates comparison of tissue δ13C collected over multiple years. To exemplify the importance of accounting for atmospheric CO2 δ13C depletion, we applied the correction to a dataset of collagen δ13C obtained from mountain lion (Puma concolor) bone samples collected in California between 1893 and 1995. Before correction, in three of four ecoregions collagen δ13C decreased significantly concurrent with depletion of atmospheric CO2 δ13C (n ≥ 32, P ≤ 0.01). Application of the correction to collagen δ13C data removed trends from regions demonstrating significant declines, and measurement error associated with the correction did not add substantial variation to adjusted estimates. Controlling for long-term atmospheric variation and correcting tissue samples for changes in isotopic baseline facilitate analysis of samples that span a large temporal range.

Original languageEnglish (US)
Pages (from-to)148-156
Number of pages9
JournalOecologia
Volume146
Issue number1
DOIs
StatePublished - Nov 1 2005

Fingerprint

carbon isotope
isotopes
stable isotope
collagen
Puma concolor
carbon
stable isotopes
sampling
animal tissues
ecoregions
fossil fuels
aquatic organisms
global change
combustion
food webs
plant tissues
ice
ecoregion
bones
aquatic organism

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics

Cite this

Long, Eric S. ; Sweitzer, Richard A. ; Diefenbach, Duane R. ; Ben-David, Merav. / Controlling for anthropogenically induced atmospheric variation in stable carbon isotope studies. In: Oecologia. 2005 ; Vol. 146, No. 1. pp. 148-156.
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Controlling for anthropogenically induced atmospheric variation in stable carbon isotope studies. / Long, Eric S.; Sweitzer, Richard A.; Diefenbach, Duane R.; Ben-David, Merav.

In: Oecologia, Vol. 146, No. 1, 01.11.2005, p. 148-156.

Research output: Contribution to journalArticle

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