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Combined use of radiocarbon and stable carbon isotopes for the source mixing model in a stream food web
Author(s) -
Ishikawa Naoto F.,
Finlay Jacques C.,
Uno Hiromi,
Ogawa Nanako O.,
Ohkouchi Naohiko,
Tayasu Ichiro,
Power Mary E.
Publication year - 2020
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.11541
Subject(s) - food web , invertebrate , dissolved organic carbon , algae , environmental science , stable isotope ratio , carbon fibers , radiocarbon dating , environmental chemistry , isotopes of carbon , ecology , total inorganic carbon , periphyton , isotope analysis , organic matter , total organic carbon , predation , biology , chemistry , carbon dioxide , paleontology , physics , materials science , composite material , quantum mechanics , composite number
Radiocarbon natural abundance (Δ 14 C) has emerged as a useful dietary tracer in freshwater ecology for the past decade, yet its applicability for separating aquatic and terrestrial resources has not been examined quantitatively. Here, we report Δ 14 C values of stream invertebrates in different functional feeding groups collected from the upper South Fork Eel River watershed, northern California. We found that algae‐grazing insect larvae show low Δ 14 C values (−43.1 ± 21.8‰, mean ± standard deviation, N = 6), reflecting the signal of dissolved inorganic carbon weathered from ancient inorganic carbon or respiration of old organic carbon. In contrast, the Δ 14 C values of leaf‐shredding insect larvae (21.7 ± 31.9‰, N = 5) were close to those of contemporary atmospheric CO 2 except at the SF Eel River where algal production was highest. The Δ 14 C values of predators (−6.1 ± 35.7‰, N = 14) were intermediate between those of grazers and shredders. In a Bayesian mixing model, Δ 14 C provided a more ecologically realistic estimate for terrestrial vs. aquatic source contributions to invertebrates with lower uncertainty (i.e., narrower credible interval) than did the stable carbon isotopes (δ 13 C). These results demonstrate that Δ 14 C can be used, in combination with δ 13 C, to more precisely estimate organic matter sources to stream animals.