Linear relationship between carbon and nitrogen isotope ratios along simple food chains in marine environments

Maki Noguchi Aita, Kazuaki Tadokoro, Nanako O. Ogawa, Fujio Hyodo, Reiichiro Ishii, S. Lan Smith, Toshiro Saino, Michio J. Kishi, Sei Ichi Saitoh, Eitaro Wada

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


To examine the relationship between carbon and nitrogen stable isotope (SI) ratios (δ 13C and δ 15N) of zooplankton, we analyzed samples collected bimonthly from March to October 2009, from the euphotic layers of the Oyashio current along the A-line in the western North Pacific. Isotopic ratios of higher trophic levels such as predatory zooplankton and/or long-lived zooplankton varied little with season, while those of short-lived zooplankton were variable on the δ 1513C map. We also analyzed preserved samples taken from the warm-core ring 86-B derived from the Kuroshio extension region. Although the zooplankton groups in the two regions exhibited different values in δ 15N, the δ 15N versus δ 13C slopes for each ecosystem do not show significant differences. Statistical analysis conducted together with previously published data from the Antarctic Ocean and the Gulf of Alaska suggested a similar δ 15N versus δ 13C slope throughout the four regions. We attributed this common slope to physiological aspects of feeding processes (e.g. the kinetic isotope effects inherent in the processes of amino acid synthesis). The common pattern for all four oceanic regions suggests that SIs may be used to elucidate general patterns in ecosystems and biogeochemical cycles.

Original languageEnglish
Pages (from-to)1629-1642
Number of pages14
JournalJournal of Plankton Research
Issue number11
Publication statusPublished - Nov 2011


  • carbon
  • food chain
  • isotopic fractionation
  • nitrogen
  • stable isotopes

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology


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