The distribution and significance of <i>Richelia intracellularis</i> Schmidt in the North Pacific Central Gyre1

Venrick, Elizabeth L.

doi:10.4319/lo.1974.19.3.0437

Cited by 140 publications

(107 citation statements)

References 8 publications

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“…This pattern of alternation in the dominance of N 2 fixation, as was also noted in the spatial distributions of Group B and Trichodesmium in the Amazon plume waters (Foster et al, 2007), implies that unicellular diazotrophs could have a potentially significant impact on N 2 fixation and nitrogen fluxes in mid to higher latitude regions where Trichodesmium has not been observed. Our next objective, to include modeled N 2 fixation rates of diatom-diazotroph associations (for example, Rhizosolenia-Richelia) that are known to contribute substantially to N 2 fixation in the North Pacific (Venrick, 1974;Karl et al, 1992;Capone, 2001), will allow for a more complete assessment of the importance of unicellular diazotrophs to N 2 fixation at Station ALOHA.…”

Section: Discussionmentioning

confidence: 99%

Modeled contributions of three types of diazotrophs to nitrogen fixation at Station ALOHA

et al. 2007

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A diagnostic model based on biomass and growth was used to assess the relative contributions of filamentous nonheterocystous Trichodesmium and unicellular cyanobacteria, termed Groups A and B, to nitrogen fixation at the North Pacific Station ALOHA over a 2-year period. Average (and 95% confidence interval, CI) annual rates of modeled monthly values for Trichodesmium, Group B and Group A were 92 (52), 14 (4) and 12 (8) mmol N per m 2 per year, respectively. The fractional contribution to modeled instantaneous nitrogen fixation by each diazotroph fluctuated on interannual, seasonal and shorter time scales. Trichodesmium fixed substantially more nitrogen in year 1 (162) than year 2 (12). Group B fixed almost two times more nitrogen in year 1 (17) than year 2 (9). In contrast, Group A fixed two times more nitrogen in year 2 (16) than year 1 (8). When including uncertainties in our estimates using the bootstrap approach, the range of unicellular nitrogen fixation extended from 10% to 68% of the total annual rate of nitrogen fixation for all three diazotrophs. Furthermore, on a seasonal basis, the model demonstrated that unicellular diazotrophs fixed the majority (51%-97%) of nitrogen during winter and spring, whereas Trichodesmium dominated nitrogen fixation during summer and autumn (60%-96%). Sensitivity of the modeled rates to some parameters suggests that this unique attempt to quantify relative rates of nitrogen fixation by different diazotrophs may need to be reevaluated as additional information on cell size, variability in biomass and C:N, and growth characteristics of the different cyanobacterial diazotrophs become available.

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Section: Discussionmentioning

confidence: 99%

Modeled contributions of three types of diazotrophs to nitrogen fixation at Station ALOHA

et al. 2007

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“…(Foster et al, , 2011, respectively. These diatom-diazotroph associations are well documented and globally distributed through the oligotrophic ocean and are thought to have an important role in carbon sequestration (Venrick, 1974;Janson et al, 1999;Subramaniam et al, 2008;Karl et al, 2012;Villareal et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

A novel cohabitation between two diazotrophic cyanobacteria in the oligotrophic ocean

et al. 2014

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The cyanobacterial genus Trichodesmium is biogeochemically significant because of its dual role in nitrogen and carbon fixation in the oligotrophic ocean. Trichodesmium species form colonies that can be easily enriched from the water column and used for shipboard rate measurements to estimate their contribution to oceanic carbon and nitrogen budgets. During a July 2010 cruise near the Hawaiian Islands in the oligotrophic North Pacific Subtropical Gyre, a specific morphology of Trichodesmium puff-form colonies were examined under epifluorescent microscopy and found to harbor a colonial endobiont, morphologically identified as the heterocystous diazotrophic cyanobacterium Calothrix. Using unialgal enrichments obtained from this cruise, we show that these Calothrix-like heterocystous cyanobionts (hetDA for 'Trichodesmium-associated heterocystous diazotroph') fix nitrogen on a diurnal cycle (maximally in the middle of the light cycle with a detectable minimum in the dark). Gene sequencing of nifH from the enrichments revealed that this genus was likely not quantified using currently described quantitative PCR (qPCR) primers. Guided by the sequence from the isolate, new hetDA-specific primers were designed and subsequent qPCR of environmental samples detected this diazotroph from surface water to a depth of 150 m, reaching densities up to B9 Â 10 3 l À 1 . Based on phylogenetic relatedness of nifH and 16S rRNA gene sequences, it is predicted that the distribution of this cyanobiont is not limited to subtropical North Pacific but likely reaches to the South Pacific and Atlantic Oceans. Therefore, this previously unrecognized cohabitation, if it reaches beyond the oligotrophic North Pacific, could potentially influence Trichodesmium-derived nitrogen fixation budgets in the world ocean.

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“…Diatomdiazotroph associations containing the cyanobiont R. intracellularis and the filamentous non-heterocystous Trichodesmium spp., were traditionally considered the dominant nitrogen-fixing plankton in marine tropical oceans. The 'New N' supplied by these organisms, and a variety of small unicellular diazotrophs described recently (Zehr et al, 2001;Montoya et al, 2004;Zehr et al, 2007), contribute substantially to these systems (Venrick, 1974;Mague et al, 1977;Carpenter and Romans, 1991;Capone et al, 1997;Carpenter et al, 1999;Arrigo, 2005). In the tropical North Atlantic, extensive N 2 fixation by blooms of diatoms and R. intracellularis produced nearly 70% of total N demand in surface waters Janson et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

“…It is usually found as an endosymbiont within diatoms such as Rhizosolenia spp, Hemiaulus spp, or as an episymbiont attached to Chaetoceros spp. (Venrick, 1974;Taylor, 1982;Sundstrom, 1984;Gomez et al, 2005). Diatomdiazotroph associations containing the cyanobiont R. intracellularis and the filamentous non-heterocystous Trichodesmium spp., were traditionally considered the dominant nitrogen-fixing plankton in marine tropical oceans.…”

Section: Introductionmentioning

confidence: 99%

Seasonal dynamics of the endosymbiotic, nitrogen-fixing cyanobacterium Richelia intracellularis in the eastern Mediterranean Sea

et al. 2008

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Biological nitrogen fixation has been suggested as an important source of nitrogen for the ultraoligotrophic waters of the Levantine Basin of the Mediterranean Sea. In this study, we identify and characterize the spatial and temporal distribution of the N-fixing (diazotrophic) cyanobacterium Richelia intracellularis. R. intracellularis is usually found as an endosymbiont within diatoms such as Rhizosolenia spp and Hemiaulus spp. and is an important diazotroph in marine tropical oceans. In this study, two stations off the Mediterranean coast of Israel were sampled monthly during 2005-2007. R. intracellularis was identified by microscopy and by reverse transcribed-PCR which confirmed a 98.8% identity with known nifH sequences of R. intracellularis from around the world. The diatom-diazotroph associations were found throughout the year peaking during autumn (October-November) at both stations. Abundance of R. intracellularis ranged from 10 to 55 heterocysts l À1 and correlated positively with the dissolved Si(OH) 4 /(NO 3 þ NO 2 ) ratio in surface waters. Although the rates of nitrogen fixation were very low, averaging B1.1 nmol N l À1 day À1 for the R. intracellularis size fraction (410 lm) from surface waters, they correlated positively with heterocyst counts during thermal stratification. The lack of large-scale diatom-diazotroph blooms and the low rates of nitrogen fixation by these diazotrophs may result from the P-starved conditions affecting the Levantine basin.

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The distribution and significance of Richelia intracellularis Schmidt in the North Pacific Central Gyre1

Cited by 140 publications

References 8 publications

Modeled contributions of three types of diazotrophs to nitrogen fixation at Station ALOHA

Modeled contributions of three types of diazotrophs to nitrogen fixation at Station ALOHA

A novel cohabitation between two diazotrophic cyanobacteria in the oligotrophic ocean

Seasonal dynamics of the endosymbiotic, nitrogen-fixing cyanobacterium Richelia intracellularis in the eastern Mediterranean Sea

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