Complementary pathways of dissolved organic carbon removal pathways in clear-water Amazonian ecosystems: photochemical degradation and bacterial uptake

Abstract Dissolved organic carbon (DOC) photochemical reactions establish important links between DOC and planktonic bacteria. We hypothesize that seasonal changes in DOC quality, related to the flood pulse, drive the effects of light–DOC interactions on uptake by planktonic bacteria uptake in clear...

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Bibliographic Details
Published in:FEMS microbiology ecology 2006-04, Vol.56 (1), p.8-17
Main Authors: Amado, André M., Farjalla, Vinicius F., Esteves, Francisco de A., Bozelli, Reinaldo L., Roland, Fábio, Enrich-Prast, Alex
Format: Article
Language:English
Subjects:
Amazon
Aquatic ecosystems
Bacteria
Bacteria - metabolism
Bacteriology
Biodegradation
Biological and medical sciences
Brazil
Carbon - metabolism
Chlorophyll - analysis
CO2 production
Dissolved organic carbon
Ecology
Ecosystem
Ecosystems
Fresh Water
Fundamental and applied biological sciences. Psychology
hydrological variability
Hydrology
Lakes
Light effects
Microbiology
Mineralization
Miscellaneous
Oxidation
photochemical degradation
Photochemical reactions
Photochemicals
Photolysis
planktonic bacteria
Rivers
Seasonal variations
Seasons
Sunlight
Water analysis
Water Microbiology
Water sampling
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Summary:Abstract Dissolved organic carbon (DOC) photochemical reactions establish important links between DOC and planktonic bacteria. We hypothesize that seasonal changes in DOC quality, related to the flood pulse, drive the effects of light–DOC interactions on uptake by planktonic bacteria uptake in clear-water Amazonian ecosystems. Water samples from two ecosystems (one lake and one stream) were incubated in sunlight during different hydrological periods and were then exposed to bacterial degradation. Photochemical and bacterial degradation were driven by seasonal DOC inputs. Bacterial mineralization was the main degradation pathway of autochthonous DOC in the lake, while allochthonous DOC was more available for photochemical oxidation. We suggest that sunlight enhances the bacterial uptake of refractory DOC but does not alter uptake of labile forms. We also observed a positive relationship between sunlight and bacterial degradation of DOC, instead of competition. We conclude that photochemical reactions and bacteria complementarily degrade the different sources of DOC during the flood pulse in Amazonian clear-water aquatic ecosystems.
ISSN:0168-6496
1574-6941
DOI:10.1111/j.1574-6941.2006.00028.x