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| Titel |
An isotopic (Δ14C, δ13C, and δ15N) investigation of the composition of particulate organic matter and zooplankton food sources in Lake Superior and across a size-gradient of aquatic systems |
| VerfasserIn |
P. K. Zigah, E. C. Minor, J. P. Werne, S. Leigh McCallister |
| 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 ; 9, no. 9 ; Nr. 9, no. 9 (2012-09-25), S.3663-3678 |
| Datensatznummer |
250007294
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| Publikation (Nr.) |
 copernicus.org/bg-9-3663-2012.pdf |
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| Zusammenfassung |
| Food webs in aquatic systems can be supported both by carbon from recent
local primary productivity and by carbon subsidies, such as material from
terrestrial ecosystems, or past in situ primary productivity. The importance
of these subsidies to respiration and biomass production remains a topic of
debate. While some studies have reported that terrigenous organic
carbon supports disproportionately high zooplankton production, others have
suggested that phytoplankton preferentially support zooplankton production
in aquatic ecosystems. Here we apply natural abundance radiocarbon (Δ14C)
and stable isotope (δ13C, δ15N)
analyses to show that zooplankton in Lake Superior selectively incorporate
recently fixed, locally produced (autochthonous) organic carbon even though
other carbon sources are readily available. Estimates from Bayesian isotopic
modeling based on Δ14C and δ13C values show that
the average lake-wide median contributions of recent in-lake primary
production and terrestrial, sedimentary, and bacterial organic carbon to the
bulk POM in Lake Superior were 58%, 5%, 33%, and 3%,
respectively. However, isotopic modeling estimates also show that recent in
situ production contributed a disproportionately large amount (median,
91%) of the carbon in mesozooplankton biomass in Lake Superior. Although
terrigenous organic carbon and old organic carbon from resuspended sediments
were significant portions (median, 38%) of the available basal food
resources, these contributed only a small amount to mesozooplankton biomass. Comparison of zooplankton food sources based on their
radiocarbon composition showed that terrigenous organic carbon was
relatively more important in rivers and small lakes, and the proportion of
terrestrially derived material used by zooplankton correlated with the
hydrologic residence time and the ratio of basin area to water surface area. |
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