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| Titel |
Bacterial carbon sources in coastal sediments: a cross-system analysis based on stable isotope data of biomarkers |
| VerfasserIn |
S. Bouillon, H. T. S. Boschker |
| 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 ; 3, no. 2 ; Nr. 3, no. 2 (2006-05-03), S.175-185 |
| Datensatznummer |
250000887
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| Publikation (Nr.) |
 copernicus.org/bg-3-175-2006.pdf |
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| Zusammenfassung |
| Coastal ecosystems are typically highly productive, and the sediments in
these systems receive organic matter from a variety of local and imported
sources. To assess if general patterns are present in the origin of carbon
sources for sedimentary bacteria and their relation to the origin of the
sediment organic carbon pool, we compiled both literature and new data on
δ13C of bacterial biomarkers (the phospholipid derived
fatty acids i+a15:0), along with δ13C data on sediment organic
carbon (δ13CTOC) and macrophyte biomass from a variety of
typical near-coastal systems. These systems included mangroves, salt marshes
(both C3 and C4-dominated sites), seagrass beds, and macroalgae-based
systems, as well as unvegetated sediments. First, our δ13Ci+a15:0 data showed large variability over the entire range of
δ13CTOC, indicating that in many settings, bacteria may
depend on carbon derived from various origins. Secondly, systems where local
macrophyte production is the major supplier of organic carbon for in situ
decomposition are generally limited to organic carbon-rich, peaty sites (TOC>10 wt%),
which are likely to make up only a small part of the global
area of vegetated coastal systems. These carbon-rich sediments also provided
a field based estimate of isotopic fractionation between bacterial carbon
sources and biomarkers (-3.7±2.1), which is similar to the expected
value of about -3 associated with the biosynthesis of fatty acids. Thirdly,
only in systems with low TOC (below ~1 wt%), we consistently found
that bacteria were selectively utilizing an isotopically enriched carbon
source, which may be root exudates but more likely is derived from
microphytobenthos. In other systems with between ~1 and 10 wt% TOC,
bacteria appear to show on average little selectivity and δ13Ci+a15:0
data generally follow the δ13CTOC, even
in systems where the TOC is a mixture of algal and macrophyte sources that
generally are believed to have a very different degradability. |
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