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| Titel |
Chlorophyll a-specific Δ14C, δ13C and δ15N values in stream periphyton: implications for aquatic food web studies |
| VerfasserIn |
N. F. Ishikawa, M. Yamane, H. Suga, N. O. Ogawa, Y. Yokoyama, N. Ohkouchi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 22 ; Nr. 12, no. 22 (2015-11-26), S.6781-6789 |
| Datensatznummer |
250118181
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| Publikation (Nr.) |
 copernicus.org/bg-12-6781-2015.pdf |
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| Zusammenfassung |
| Periphytic algae attached to a streambed substrate (periphyton) are an
important primary producer in stream ecosystems. We determined the isotopic
composition of chlorophyll a in periphyton collected from a stream flowing on
limestone bedrock in the Seri River, central Japan. Stable isotope ratios of
carbon (δ13C) and nitrogen (δ15N) and natural
radiocarbon abundances (Δ14C) were measured in chlorophyll a
(δ13Cchl, δ15Nchl and Δ14Cchl) and bulk (δ13Cbulk, δ15Nbulk and Δ14Cbulk) for periphyton, a pure
aquatic primary producer (Cladophora sp.) and a terrestrial primary producer (Quercus glauca).
Periphyton δ13Cbulk and δ13Cchl values
did not necessarily correspond to δ13Cbulk for an
algal-grazing specialist (Epeorus latifolium). Periphyton Δ14Cchl values
(−258 ‰ in April and −190 ‰ in
October) were slightly lower than Δ14Cbulk values
(−228 ‰ in April and −179 ‰ in
October) but were close to the Δ14C value for dissolved
inorganic carbon (DIC; −217 ± 31 ‰), which is a
mixture of weathered carbonates (Δ14C = −1000 ‰), CO2 derived from aquatic and terrestrial
organic matters (variable Δ14C) and dissolved atmospheric
CO2 (Δ14C approximately +30 ‰ in
2013). Δ14Cchl values were also close to Δ14Cbulk for E. latifolium (−215 ‰ in April and
−199 ‰ in October) and Cladophora sp. (−210 ‰), whereas the Δ14Cbulk value for Q. glauca
(+27 ‰) was closer to Δ14C for
atmospheric CO2. Although the bulk isotopic composition of periphyton
is recognised as a surrogate for the photosynthetic algal community, natural
periphyton is a mixture of aquatic and terrestrial organic materials. Our
results indicate that the bulk periphyton matrix at the study site consists
of 89 to 95 % algal carbon (derived from 14C-depleted DIC) and
5 to 11 % terrestrial organic carbon (derived from 14C-enriched
atmospheric CO2). |
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