| Experimental evidence that terrestrial carbon subsidies increase CO2 flux from lake ecosystems. | |
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MedLine Citation:
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PMID: 14689297 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Subsidies are donor-controlled inputs of nutrients and energy that can affect ecosystem-level processes in a recipient environment. Lake ecosystems receive large inputs of terrestrial carbon (C) in the form of dissolved organic matter (DOM). DOM inputs may energetically subsidize heterotrophic bacteria and determine whether lakes function as sources or sinks of atmospheric CO(2). I experimentally tested this hypothesis using a series of mesocosm experiments in New England lakes. In the first experiment, I observed that CO(2) flux increased by 160% 4 days following a 1,000 microM C addition in the form of DOM. However, this response was relatively short lived, as there was no effect of DOM enrichment on CO(2) flux beyond 8 days. In a second experiment, I demonstrated that peak CO(2) flux from mesocosms in two lakes increased linearly over a broad DOM gradient (slope for both lakes=0.02+/-0.001 mM CO(2).m(-2) day(-1) per microM DOC, mean+/-SE). Concomitant changes in bacterial productivity and dissolved oxygen strengthen the inference that increasing CO(2) flux resulted from the metabolism of DOM. I conducted two additional studies to test whether DOM-correlated attributes were responsible for the observed change in plankton metabolism along the subsidy gradient. First, terrestrial DOM reduced light transmittance, but experimental shading revealed that this was not responsible for the observed patterns of CO(2) flux. Second, organically bound nitrogen (N) and phosphorus (P) accompanied DOM inputs, but experimental nutrient additions (without organic C) caused mesocosms to be saturated with CO(2). Together, these results suggest that C content of terrestrial DOM may be an important subsidy for freshwater bacteria that can influence whether recipient aquatic ecosystems are sources or sinks of atmospheric CO(2). |
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Authors:
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Jay T Lennon |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. Date: 2003-12-19 |
Journal Detail:
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Title: Oecologia Volume: 138 ISSN: 0029-8549 ISO Abbreviation: Oecologia Publication Date: 2004 Mar |
Date Detail:
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Created Date: 2004-03-25 Completed Date: 2004-05-07 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0150372 Medline TA: Oecologia Country: Germany |
Other Details:
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Languages: eng Pagination: 584-91 Citation Subset: IM |
Affiliation:
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Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755-3576, USA. Jay.T.Lennon@Dartmouth.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Carbon
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analysis* Carbon Dioxide / analysis* Ecosystem* Fresh Water / analysis* Humans Soil Pollutants / analysis* |
| Chemical | |
Reg. No./Substance:
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0/Soil Pollutants; 124-38-9/Carbon Dioxide; 7440-44-0/Carbon |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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