The loss of organic nitrogen during marine primary production may be significantly overestimated when using 15N substrates

Flynn, Kevin J.; Berry, Lorraine

doi:10.1098/rspb.1999.0684

Cited by 35 publications

(40 citation statements)

References 39 publications

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“…it is likely that DCAA were produced during bacterial mineralization of riverine DON. In the Koiguste transect, the coincidence of maximum chl a concentrations and a minimum DCAA versus DON content at the outer station, 13 km from the shore, may support a low release of DCAA from growing algae as observed by Flynn & Berry (1999). The amount of phaeopigments also increased at the outer station (Table l ) , but the declining DCAA concentrations do not indicate that dead or inactive algae contributed DCAA to the water.…”

Section: -mentioning

confidence: 76%

“…In the present study, DCAA made up a major portion of DON, but the abundance of DCAA appeared not to correlate well with the biomass of living or dead phytoplankton. algae typically release a minor amount of DCAA Planktonic algae have been shown to produce DCAA (Flynn & Berry 1999). Another potential source of (Hellebust 1965, Ittekkot 1982 …”

Section: Fluxes Of Dissolved Nitrogen Compounds In the Gulf Of Rigamentioning

confidence: 99%

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Occurrence and bacterial cycling of dissolved nitrogen in the Gulf of Riga, the Baltic Sea

Jørgensen¹,

Tranvik²,

Berg³

1999

Mar. Ecol. Prog. Ser.

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Occurrence, composition and biolability of total dissolved nitrogen (TDN, including dissolved inorganic and organic N ( [DIN and DON]) were examined in May and July 1996 in the northern (Koiguste transect) and southern part (Saulkrasti transect) of the Gulf of Riga. In the Saulkrasti transect, the Daugava River was a major source of TDN as indicated by concentrations of up to 60 pM TDN in the river plume, compared to about 20 p M TDN in the open gulf. DON made up 80 to 90% of the TDN, but on May 16 a nitrate-rich river plume lowered the proportion of DON to 65%. Riverine DIN and DON stimulated the biological activity along the transect in May, but apparently not in July. In the Koiguste transect, concentrations of TDN were 0.5-fold lower than at Saulkrasti. In May, input of terrestrial nutrients to the inner part of the transect probably increased the biological production. In both transects, the labile DON fraction, defined as bacterial DON degradation over a week, was estimated at 4 to 29%, with an average of 13%. Dissolved combined amino acids (DCAA) made up 10 to 30% of the DON. A high DON lability coincided with a large proportion of DCAA, relative to TDN, or a high algal biomass. The L/D rat10 of especially dissolved combined glutamic acid appeared to be a potential indicator of DON lability DCAA, as well as dissolved free amino acids (DFAA), were dominant nutrient sources to the bacteria, on average sustaining 77 % (range 8 to 136%) of the bacterial N demand. In addition to amino acids, the bacteria incorporated or released DIN and urea. The effect of solar radiation on DON biolability was tested, but no consistent evidence for a light effect on transformation or bacterial utilization of recalcitrant DON was found. Our results show that there is an active microbial cycling of DON in the gulf, driven in part by input of N from the Daugava River. In summer, availability of assimilable N appears to limit the microbial activity as indicated by an estimated C/N ratio of 43 of labile DOM, as compared to a ratio of 4 in May. The microbial N dynamics in the Gulf of Riga are comparable to low-eutrophic estuaries and do not indicate direct eutrophication effects.

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Section: -mentioning

confidence: 76%

Section: Fluxes Of Dissolved Nitrogen Compounds In the Gulf Of Rigamentioning

confidence: 99%

Occurrence and bacterial cycling of dissolved nitrogen in the Gulf of Riga, the Baltic Sea

Jørgensen¹,

Tranvik²,

Berg³

1999

Mar. Ecol. Prog. Ser.

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“…The higher release of DCAA in the light suggests that this release is a photosynthetically driven process, although Harlin and Craigie (1975) found no difference in light-dark DON release rates for a brown macroalgae. Phytoplankton may release 25-41% of DIN uptake as DON on short time scales (Bronk et al 1994) and much of this release may be DFAA and DCAA (Flynn and Berry 1999). Jorgensen (1982) found increased water column DFAA in the presence of U. lactuca, but based on the amino acid composition concluded that the DFAA were exudates from bacteria stimulated by algal DON release.…”

Section: Sediment Fluxes and The Influence Of Benthic Microalgaethe Dmentioning

confidence: 99%

Benthic algae control sediment—water column fluxes of organic and inorganic nitrogen compounds in a temperate lagoon

Tyler

McGlathery

Anderson

2003

Limnology & Oceanography

144

101

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Coastal lagoons are a common land-margin feature worldwide and function as an important filter for nutrients entering from the watershed. The shallow nature of lagoons leads to dominance by benthic autotrophs, which can regulate benthic-pelagic coupling. Here we demonstrate that both microalgae and macroalgae are important in controlling dissolved inorganic as well as organic nitrogen (DIN and DON) fluxes between the sediments and the water column. Fluxes of nitrogen (NH , NO , DON, urea, and dissolved free and combined amino acids [DFAA,DCAA]) and O 2 were measured from October 1998 through August 1999 in sediment cores collected from Hog Island Bay, Virginia. Cores were collected from four sites representing the range of environmental conditions across this shallow lagoon: muddy, high-nutrient and sandy, low-nutrient sites that were both dominated by benthic microalgae, and a mid-lagoon site with fine sands covered by dense macroalgal mats. Sediment-water column DON fluxes were highly variable and comparable in magnitude to DIN fluxes; fluxes of individual compounds (urea, DFAA, DCAA) often proceeded simultaneously in different directions. Where sediment metabolism was net autotrophic because of microalgal activity, TDN (total dissolved nitrogen) fluxes, mostly comprised of DIN, urea, and DFAA, were directed into the sediments. Heterotrophic sediments, including those underlying macroalgal mats, were a net source of TDN, mostly as DIN. Macroalgae intercepted sediment-water column fluxes of DIN, urea, and DFAA, which accounted for 27-75% of calculated N demand. DON uptake was important in satisfying macroalgal N demand seasonally and where DIN concentrations were low. Up to 22% of total N uptake was released to the water column as DCAA. Overall, macroalgae assimilated, transformed, and rereleased to the water column both organic and inorganic N on short (minutes-hours) and long (months) time scales. Microalgae and macroalgae clearly regulate benthic-pelagic coupling and thereby influence transformations and retention of N moving across the land-sea interface.

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“…On the contrary, nitrogen-replete cells are likely to release more organic nitrogen. Nitrogen release is related to nitrogen uptake by the phytoplankton (Bronk & Glibert 1993, Flynn & Berry 1999. Studies on the relationship between DON (dissolved organic nitrogen) release and the nitrogen states of algae will contribute to the clarification of phytoplankton dynamics and nitrogen cycling in aquatic environments.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Release of dissolved organic nitrogen from Scenedesmus quadricauda (Chlorophyta) and Microcystis novacekii (Cyanobacteria)

Nagao¹,

Miyazaki²

2002

Aquat. Microb. Ecol.

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We measured the time-course of dissolved organic nitrogen (DON) release and inorganic nitrogen assimilation in the freshwater phytoplankton Scenedesmus quadricauda (Turp.) Brébission and Microcystis novacekii (Kom.) Comp. by the 15 N tracer method. The algae were cultivated under nitrogen-limited or -replete conditions. We estimated the total DON release, release of recently assimilated nitrogen (RANR) and net nitrogen assimilation (NNA), using ammonium chloride or sodium nitrate as the nitrogen source. In the 15 N tracer incubation of S. quadricauda prior to 1 h and in M. novacekii prior to 3-6 h, minimal release of total DON was observed under the nitrogen-limited conditions. This result suggests that nitrogen-limited cells efficiently use incorporated nitrogen. Appreciable release of total DON was observed in the 15 N incubation of nitrogen-replete S. quadricauda and M. novacekii. RANR in both nitrogen-limited and -replete algae was smaller than, and lagged behind, release of total DON, indicating that newly assimilated nitrogen was less easily released. NNA by nitrogen-limited S. quadricauda increased from the onset of the tracer incubation, showing that ambient nitrogen was needed for nitrogen-limited cells from the beginning of the incubation. Nitrogen-replete S. quadricauda showed no NNA during the first 1 h of the tracer incubation, suggesting that the alga did not require external nitrogen immediately after being transferred from nitrogen-replete conditions. This study shows that nitrogen release and assimilation are markedly affected by the nutritional states of the algae. KEY WORDS: Ammonium · Nitrogen assimilation · Organic nitrogen release · Microcystis novacekii · Nitrate · Scenedesmus quadricauda Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 27: [275][276][277][278][279][280][281][282][283][284] 2002 variously reported in different DOM-release studies. Watt (1969) and Fogg (1983) suggested that the released substances consist mainly of low molecular weight compounds, such as amino acids and early photosynthates. However, Nalewajko & Schindler (1976), Chrost & Faust (1983) and Sundh (1989) reported that released DOM is often dominated by compounds with high molecular weights. These discrepancies seem related to the nutritional and physiological states of the algae tested.Release of organic nitrogen by phytoplankton may be influenced by the nitrogen demand and physiology of the algal cells, as was suggested by the studies on DOM release. Nitrogen is an important factor for cellular nutrition and physiology. Nitrogen-limited cells will not readily release organic nitrogen, because nitrogen is required for growth and maintenance of optimal cell conditions. On the contrary, nitrogen-replete cells are likely to release more organic nitrogen. Nitrogen release is related to nitrogen uptake by the phytoplankton (Bronk & Glibert 1993, Flynn & Berry 1999. Studies on the relationship between DON (dissolved organic nitrogen) release and the nitroge...

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The loss of organic nitrogen during marine primary production may be significantly overestimated when using 15N substrates

Cited by 35 publications

References 39 publications

Occurrence and bacterial cycling of dissolved nitrogen in the Gulf of Riga, the Baltic Sea

Occurrence and bacterial cycling of dissolved nitrogen in the Gulf of Riga, the Baltic Sea

Benthic algae control sediment—water column fluxes of organic and inorganic nitrogen compounds in a temperate lagoon

Release of dissolved organic nitrogen from Scenedesmus quadricauda (Chlorophyta) and Microcystis novacekii (Cyanobacteria)

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