Production and utilization of dissolved organic carbon during an experimental diatom bloom

Norrman, Bo; Zwelfel, Ulla Li; Hopkinson, Charles S.; Fry, B.

doi:10.4319/lo.1995.40.5.0898

Cited by 207 publications

(177 citation statements)

References 29 publications

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“…4a). Conversely, the POM C/N ratio decreased after 15 August while the DOM C/N ratio increased, which could be related to the release of carbohydrate (Norrman, Zweifel, Hopkinson, & Fry, 1995;Søndergaard et al, 2000). Therefore, the fresh organic matter produced inshore at the origin of the filament was still present off-shore.…”

Section: The Filament Studymentioning

confidence: 91%

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Off-shelf fluxes of labile materials by an upwelling filament in the NW Iberian Upwelling System

Álvarez-Salgado

Doval

Borges

et al. 2001

Progress in Oceanography

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Daily changes in the concentrations of carbon and nitrogen species were monitored during the course of a Lagrangian drifter experiment in a recurrent upwelling filament south of Cape Finisterre (NW Iberian Upwelling System). A drifting buoy released at the southern edge of the upwelling centre generated by the Cape moved 60km southwestwards from 3 to 7 August 1998. Organic matter in the 50m deep study water mass (average 77±2 µM C) consisted of: 57µM C of dissolved organic matter (DOM) with a C/N molar ratio of 19±2; 6µM C of DOM with a C/N ratio of 9±2, and 14µM C of 50% DOM and 50% suspended organic matter (POM susp ) with a C/N ratio of 6.0±0.4.Net conversion of consumed inorganic salts into accumulated TOM=POM susp +DOM was ෂ40% for nitrogen and ෂ30% for carbon. Since the parcel of water crossed the shelf-edge, these conversion efficiencies are equivalent to net horizontal export-ratio of 0.4 and 0.3 respectively. A second drifter was deployed in the offshore-end of the filament, and was displaced 20km west between 14 and 17 August 1998. Nitrate was exhausted in the surface water and no significant changes were observed in the variables measured during the course of the second experiment. Low C/N ratios (6.5±0.4) and rapid POM susp /DOM inter-conversion in the 20 µM C excess observed in the study volume points to the persistence of the labile materials formed on the shelf during transport to the ocean. Our data demonstrate a) the key role of upwelling filaments in off-shelf export of organic materials and b) the major contribution of DOM to this horizontal export, a previously unaccounted amount.The high nitrogen content of the materials exported make them attractive organic substrates for use by microbial populations in the adjacent oligotrophic ocean. 

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Section: The Filament Studymentioning

confidence: 91%

“…Although this time segregation has been observed in cultures (e.g. Norrman et al, 1995), this is the first observation of it in the field. The efficiency of conversion of NO 3 Ϫ consumption into TON accumulation during the transit of the surface coastal waters from Cape Finisterre upwelling centre to the ocean was ෂ40%.…”

Section: Net Consumption Of Nomentioning

confidence: 99%

Off-shelf fluxes of labile materials by an upwelling filament in the NW Iberian Upwelling System

Álvarez-Salgado

Doval

Borges

et al. 2001

Progress in Oceanography

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“…A number of studies (Søndergaard et al, 2000;Jørgensen, 1986;Norrman et al, 1995), have implicated phytoplankton in the release of DOM AUT . We therefore regressed Table 4 which show that values of E 254 and E 280 derived for DOM AUT are similar to those reported for DOM from Lake Fryxell (Chin et al, 1994;Weishaar et al, 2003).…”

Section: Sources Of Lakewater Dommentioning

confidence: 99%

Functional variability of dissolved organic matter from the surface water of a productive lake

et al. 2008

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River Fulvic Acid was used as a quality control standard. For 9 of the assays, variability among DOM samples was significantly (p<0.01) greater than could be explained by analytical error. Seasonal trends observed for 6 of the assays could be explained by a simple mixing model in which the two end-members were DOM from the catchment (allochthonous) and DOM produced within the lake (autochthonous). The fraction of autochthonous DOM predicted by the model is significantly correlated (p <0.01) with chlorophyll concentration, consistent with production from phytoplankton. Autochthonous DOM is less light-absorbing, less fluorescent, more hydrophilic, and possesses fewer proton-dissociating groups, than allochthonous material.

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“…On the one hand, short-term incubation studies (i.e., days to months) indicate that bacteria consume labile, recently produced DOC (Coffin et al 1993;Carlson andDucklow 1995, 1996;Cherrier et al 1996;Coffin and Connolly 1997). On the other hand, as the concentration of oceanic bulk DOC is assumed to be at steady state (Norrman et al 1995;Carlson and Ducklow 1996) and has an average conventional age of ϳ4,000-6,000 yr B.P. (Williams and Druffel 1987;Bauer et al 1992;Druffel et al 1992), it is generally thought that bacterial remineralization must also be one of the ultimate sinks for older, presumably more refractory bulk DOC constituents (Williams and Carlucci 1976).…”

mentioning

confidence: 99%

Radiocarbon in marine bacteria: Evidence for the ages of assimilated carbon

Cherrier

Bauer

Druffel

et al. 1999

Limnology & Oceanography

107

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It is generally accepted that marine bacteria utilize labile, recently produced components of bulk dissolved organic matter. This interpretation is based largely on indirect measurements using model compounds and plankton‐derived organic matter. Here, we present an assessment of the relative proportions of modern and older dissolved organic carbon (DOC) utilized by marine bacteria. Bacterial nucleic acids were collected from both estuarine (Santa Rosa Sound, FL) and open‐ocean (eastern North Pacific) sites, and the natural radiocarbon signatures of the nucleic acid carbon in both systems were determined. Bacterial nucleic acids from Santa Rosa Sound were significantly enriched in radiocarbon with respect to the bulk DOC and were similar to the radiocarbon signature of atmospheric CO2 at the time of sampling, indicating that these bacteria exclusively assimilate a modern component of the estuarine bulk DOC. In contrast, bacterial nucleic acids from the oceanic site were enriched in 14C relative to the bulk DOC but depleted in 14C with respect to modern surface dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POCsusp). This suggests that open‐ocean bacteria assimilate both modern and older components of DOC. The distinct radiocarbon signatures of the nucleic acids at these two sites (i.e., +120 ± 17‰ estuarine vs. −34 ± 24‰ oceanic) demonstrate that natural 14C abundance measurements of bacterial biomarkers are a powerful tool for investigations of carbon cycling through microbial communities in different aquatic systems.

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Production and utilization of dissolved organic carbon during an experimental diatom bloom

Cited by 207 publications

References 29 publications

Off-shelf fluxes of labile materials by an upwelling filament in the NW Iberian Upwelling System

Off-shelf fluxes of labile materials by an upwelling filament in the NW Iberian Upwelling System

Functional variability of dissolved organic matter from the surface water of a productive lake

Radiocarbon in marine bacteria: Evidence for the ages of assimilated carbon

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