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Microscale characterization of dissolved organic matter production and uptake in marine microbial mat communitiesIntertidal marine microbial mats exhibited biologically mediated uptake of low molecular weight dissolved organic matter (DOM), including D-glucose, acetate, and an L-amino acid mixture at trace concentrations. Uptake of all compounds occurred in darkness, but was frequently enhanced under natural illumination. The photosystem 2 inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) generally failed to inhibit light-stimulated DOM uptake. Occasionally, light plus DCMU-amended treatments led to uptake rates higher than light-incubated samples, possibly due to phototrophic bacteria present in subsurface anoxic layers. Uptake was similar with either 3H- or 14C-labeled substrates, indicating that recycling of labeled CO2 via photosynthetic fixation was not interfering with measurements of light-stimulated DOM uptake. Microautoradiographs showed a variety of pigmented and nonpigmented bacteria and, to a lesser extent, cyanobacteria and eucaryotic microalgae involved in light-mediated DOM uptake. Light-stimulated DOM uptake was often observed in bacteria associated with sheaths and mucilage surrounding filamentous cyanobacteria, revealing a close association of organisms taking up DOM with photoautotrophic members of the mat community. The capacity for dark- and light-mediated heterotrophy, coupled to efficient retention of fixed carbon in the mat community, may help optimize net production and accretion of mats, even in oligotrophic waters.
Document ID
20040089759
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Paerl, H. W.
(Institute of Marine Sciences, University of North Carolina at Chapel Hill Morehead City 28557, United States)
Bebout, B. M.
Joye, S. B.
Des Marais, D. J.
Date Acquired
August 21, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Limnology and oceanography
Volume: 38
Issue: 6
ISSN: 0024-3590
Subject Category
Exobiology
Funding Number(s)
CONTRACT_GRANT: OCE 89-14833
CONTRACT_GRANT: 91-15706
CONTRACT_GRANT: 90-12496
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Exobiology
NASA Program Exobiology
NASA Discipline Number 52-80
NASA Center ARC

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