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Stable isotopes in subtidal food webs: Have enriched carbon ratios in benthic consumers been misinterpreted?
Author(s) -
Nadon Marc-Olivier,
Himmelman John H.
Publication year - 2006
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 - 10.4319/lo.2006.51.6.2828
Subject(s) - benthic zone , primary producers , submarine pipeline , oceanography , shore , environmental science , isotopes of carbon , kelp , ecology , biology , total organic carbon , geology , phytoplankton , nutrient
We examined the hypothesis that the δ 13 C of benthic consumers is depleted in offshore, deeper waters where kelp and benthic microalgae are absent by conducting three analyses: (1) we analyzed δ 13 C (and δ 15 N) of consumers along a nearshore‐offshore gradient in the field, (2) we analyzed δ 13 C (and δ 15 N) of consumers placed in cages at various depths and distances from shore, and (3) we reexamined published stable isotope values for consumers taken at various depths from studies around the world. In all three situations, we did not observe the predicted change in δ 13 C values of benthic consumers. In both the literature and in our field measurements, the δ 13 C values for consumers were on average separated from the values for suspended particulate organic matter by 4%, irrespective of depth, indicating that factors other than the feeding on 13 C‐rich benthic primary producers may explain the enriched carbon ratios in benthic consumers (e.g., selective feeding on enriched particles). The hypothesis that the high δ 13 C ratio in suspension and deposit feeders reflects feeding on benthic primary producers is thus tenuous and requires further investigation.