期刊
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
卷 122, 期 7, 页码 1806-1820出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2016JG003727
关键词
benthic biofilms; dissolved organic carbon; (13)carbon; allochthonous; autochthonous; light
资金
- Austrian Science Fund [P23420-B17, Y420-B17]
- Marie Curie individual fellowship [PIEF-GA-2010-274895]
- National Science Foundation [DEB-1457457, DEB-11199922]
- Austrian Science Fund (FWF) [P23420] Funding Source: Austrian Science Fund (FWF)
- Direct For Biological Sciences
- Division Of Environmental Biology [1456978] Funding Source: National Science Foundation
- Division Of Environmental Biology
- Direct For Biological Sciences [1457217] Funding Source: National Science Foundation
Changes in the riparian vegetation along stream channels, diurnal light availability, and longitudinal fluctuations in the local light regime in streams influence primary production and carbon (C) cycling in benthic stream biofilms. To investigate the influence of light availability on the uptake dynamics of autochthonous and allochthonous dissolved organic carbon (DOC) in benthic biofilms, we experimentally added C-13-labeled allochthonous DOC to biofilms grown under light intensities ranging from 5 to 152molphotonsm(-2)s(-1). We calculated the net C flux, which showed that benthic biofilms released autochthonous DOC across the entire light gradient. Light availability and diurnal light patterns influenced C uptake by benthic biofilms. More allochthonous DOC was respired under low light availability and at night, whereas under high light availability and during the day mainly autochthonous C was respired by the benthic biofilm community. Furthermore, phenol oxidase activity (indicative of allochthonous DOC uptake) was more elevated under low light availability, whereas beta-glucosidase activity (indicative of autochthonous DOC use) increased with light intensity. Collectively, our results suggest that biofilms exposed to high light inputs preferentially used autochthonous DOC, whereas biofilms incubated at attenuated levels showed greater use of allochthonous DOC. This has implications for the spatial dynamics of DOC uptake in streams and speaks against the occurrence of priming effects in algal-dominated stream biofilms.
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