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| Titel |
Transformation and fate of microphytobenthos carbon in subtropical, intertidal sediments: potential for long-term carbon retention revealed by 13C-labeling |
| VerfasserIn |
J. M. Oakes, B. D. Eyre |
| 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 ; 11, no. 7 ; Nr. 11, no. 7 (2014-04-08), S.1927-1940 |
| Datensatznummer |
250117350
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| Publikation (Nr.) |
 copernicus.org/bg-11-1927-2014.pdf |
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| Zusammenfassung |
| Microphytobenthos (MPB) are ubiquitous in coastal sediments, but the fate of
their production (carbon biomass) is poorly defined. The processing and fate
of MPB-derived carbon in subtropical intertidal sediments was investigated
through in situ labeling with 13C-bicarbonate. Of the added 13C,
100% was fixed within ~ 4 h, suggesting that MPB
productivity was limited by inorganic carbon availability. Although there
was rapid transfer of 13C to bacteria (within 12 h), a relatively small
fraction of 13C was transferred to heterotrophs (up to 12.5% of
total fixed 13C into bacteria and 0.01% into foraminifera). MPB was
the major reservoir for 13C throughout the study, suggesting that
production of extracellular polymeric substances was limited and/or MPB
recycled 13C. This retention of 13C was reflected in remarkably
slow estimated turnover times for the MPB community (66–100 d). Over 31 d,
~ 70% of the 13C was lost from sediments. This was
primarily via resuspension (~ 55%), enhanced by elevated
freshwater flow following rainfall. A further ~ 13% was
lost via fluxes of dissolved inorganic carbon during inundation. However,
13C losses via dissolved organic carbon fluxes from inundated sediments
(0.5%) and carbon dioxide fluxes from exposed sediments (<0.1%) were minimal. The retention of ~ 30% of the carbon
fixed by MPB within one tidal exposure after > 30 d, despite high
resuspension, demonstrates the potentially substantial longer term retention
of MPB-derived carbon in unvegetated sediments and suggests that MPB may
contribute to carbon burial ("blue carbon"). |
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