Photochemically Mediated Linkages between Dissolved Organic Matter and Bacterioplankton

Moran, Mary Ann; Covert, Joseph S.

doi:10.1016/b978-012256371-3/50011-1

Cited by 53 publications

(53 citation statements)

References 55 publications

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“…The contrasting nature (polymerization vs. depolymerization) in the reactivity of light-exposed DOM has been observed by several researchers and attributed to differences in the quality of DOM (reviewed by Moran and Covert 2003;Anesio et al 2005). Our results indicate that the total dosing of light and water quality will also affect the fate of tannins.…”

Section: Discussionmentioning

confidence: 50%

Mangrove tannins in aquatic ecosystems: Their fate and possible influence on dissolved organic carbon and nitrogen cycling

Maie

Pisani

Jaffé

2008

Limnology & Oceanography

113

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We describe the fate of mangrove leaf tannins in aquatic ecosystems and their possible influence on dissolved organic nitrogen (DON) cycling. Tannins were extracted and purified from senescent yellow leaves of the red mangrove (Rhizophora mangle) and used for a series of model experiments to investigate their physical and chemical reactivity in natural environments. Physical processes investigated included aggregation, adsorption to organic matter-rich sediments, and co-aggregation with DON in natural waters. Chemical reactions included structural change, which was determined by excitation-emission matrix fluorescence spectra, and the release of proteins from tannin-protein complexes under solar-simulated light exposure. A large portion of tannins can be physically eliminated from aquatic environments by precipitation in saline water and also by binding to sediments. A portion of DON in natural water can coprecipitate with tannins, indicating that mangrove swamps can influence DON cycling in estuarine environments. The chemical reactivity of tannins in natural waters was also very high, with a half-life of less than 1 d. Proteins were released gradually from tannin-protein complexes incubated under light conditions but not under dark conditions, indicating a potentially buffering role of tanninprotein complexes on DON recycling in mangrove estuaries. Although tannins are not detected at a significant level in natural waters, they play an important ecological role by preserving nitrogen and buffering its cycling in estuarine ecosystems through the prevention of rapid DON export/loss from mangrove fringe areas and/or from rapid microbial mineralization.

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Section: Discussionmentioning

confidence: 50%

Mangrove tannins in aquatic ecosystems: Their fate and possible influence on dissolved organic carbon and nitrogen cycling

Maie

Pisani

Jaffé

2008

Limnology & Oceanography

113

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“…Variations in initial bioreactivity, age, sources and structural character (e.g. aromaticity) of DOM may affect its biological and photochemical fate during seaward transit (Mopper & Kieber 2002, Moran &Covert 2003 and references therein). In general, the balance between photoinhibition and photostimulation of DOM cycling may hinge on the initial reactivity of various subcomponents of DOM (Moran & Covert 2003).…”

mentioning

confidence: 99%

“…aromaticity) of DOM may affect its biological and photochemical fate during seaward transit (Mopper & Kieber 2002, Moran &Covert 2003 and references therein). In general, the balance between photoinhibition and photostimulation of DOM cycling may hinge on the initial reactivity of various subcomponents of DOM (Moran & Covert 2003). Thus, prediction of sunlight effects on DOM bioavailability and fate on a system scale is limited by the ability to characterize and predict the bioreactivity of the majority of organic compounds comprising the bulk DOM pool (Hedges et al.…”

mentioning

confidence: 99%

Effects of sunlight on decomposition of estuarine dissolved organic C, N and P and bacterial metabolism

McCallister¹,

Bauer²,

Kelly³

et al. 2005

Aquat. Microb. Ecol.

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The effects of natural sunlight and microbial decomposition on DOC, DON, and DOP were investigated along the salinity gradient of a temperate coastal plain estuary. The impact of sunlight-irradiated DOM on bacterial properties (bacterial abundance, production, bacterial growth efficiency [BGE]) was also followed. Surface-water light levels resulted in no detectable abiotic production of NH 4 + or PO 4 3 -or loss of DOC. Bacterial decomposition of DOC was enhanced by 27 to 200% in irradiated relative to dark treatments. There was, however, no corresponding enhancement in DON and DOP remineralization. Significant differences in bacterial decomposition of light-exposed DOC were frequently observed following prolonged incubation (> 7 d), suggesting that enhanced reactivity may result from photochemical modification of higher molecular weight organic matter. BGE in light relative to dark treatments was positively correlated (r 2 = 0.38, p < 0.01) with in situ NH 4 + concentrations. In light treatments, significantly lower N and P remineralization in August 1999 corresponded with low in situ inorganic nutrient concentrations and bacterial growth efficiency (BGE) and with elevated bacterial DOC utilization. In contrast, enhanced DOC reactivity in April 2000 during nutrient-replete conditions corresponded with net immobilization of inorganic N and P by bacterial biomass production, but without a concomitant impact on BGE. These findings suggest that the combination of photochemical and microbial alteration of DOM may increase bacterial demand for inorganic nutrients, alter BGE, and influence the partitioning of C between bacterial biomass and respiration. KEY WORDS: DOC · DON · DOP · BGE · Phototransformation · Bacterial bioassays Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 40: [25][26][27][28][29][30][31][32][33][34][35] 2005 information available for estuarine DOM that is lower in vascular plant and soil influences and higher in contributions from younger (recently produced) or algalderived organic matter ' (Moran et al. 2000). The effects of sunlight-exposure on DOM cycling in estuaries are difficult to quantify. Variations in initial bioreactivity, age, sources and structural character (e.g. aromaticity) of DOM may affect its biological and photochemical fate during seaward transit (Mopper & Kieber 2002, Moran &Covert 2003 and references therein). In general, the balance between photoinhibition and photostimulation of DOM cycling may hinge on the initial reactivity of various subcomponents of DOM (Moran & Covert 2003). Thus, prediction of sunlight effects on DOM bioavailability and fate on a system scale is limited by the ability to characterize and predict the bioreactivity of the majority of organic compounds comprising the bulk DOM pool (Hedges et al. 2000). This has sometimes been circumvented by the use of microbial activity (e.g. bacterial abundance, growth and production) as a proxy for integrating both positive and negative photochemical imp...

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“…However, there is a general consensus that sunlight has "priming effect" for bacterial uptake on old terrestrial-derived DOM as opposite to the negative effects on fresh algae-derived DOM (Moran and Covert 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Microorganisms were also observed to synthesize refractory DOM out of simple small molecules (Ogawa et al, 2001). While the role of microorganisms in DOM degradation has long been recognized, the importance of solar irradiation was only recognized 1-2 decades ago, and triggered an intensified research on the DOM photo-degradation (Moran and Zepp, 2000;Moran and Covert, 2003;Scully et al, 2004;Spencer et al, 2009;Gonsior et al, 2009;Ortega-Retuerta et al, 2010;Stubbins et al, 2010;Benner and Kaiser 2010 Stedmon et al, 2007;Housari et al, 2010;Clark et al, 2004). It has been observed that photoalterations can increase, decrease, or have no net effect on biodegradability of DOM depending on different DOM sources (Tranvik and Bertilson 2001;Moran and Zepp 2000).…”

Section: Introductionmentioning

confidence: 99%

Characterization,Sources,and Transformations of Dissolved Organic Matter (DOM) in the Florida Coastal Everglades (FCE)

Chen¹

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Photochemically Mediated Linkages between Dissolved Organic Matter and Bacterioplankton

Cited by 53 publications

References 55 publications

Mangrove tannins in aquatic ecosystems: Their fate and possible influence on dissolved organic carbon and nitrogen cycling

Mangrove tannins in aquatic ecosystems: Their fate and possible influence on dissolved organic carbon and nitrogen cycling

Effects of sunlight on decomposition of estuarine dissolved organic C, N and P and bacterial metabolism

Characterization,Sources,and Transformations of Dissolved Organic Matter (DOM) in the Florida Coastal Everglades (FCE)

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