Nitrogen Fixation by Trichodesmium and unicellular diazotrophs in the northern South China Sea and the Kuroshio in summer

Wu, Chao; Fu, Fei-Xue; Sun, Jun; Thangaraj, S. John Justin; Pujari, Laxman

doi:10.1038/s41598-018-20743-0

Cited by 35 publications

(48 citation statements)

References 65 publications

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“…These results suggested that filamentous diazotrophs contribute significantly to biological N 2 fixation in the ECS, particularly in the Kuroshio mainstream and bifurcation region. However, their new N input and contribution to N 2 fixation in Kuroshio and the offshore ECS might underestimate previously (Chang et al, 2000;Jiang et al, 2018;Shiozaki, Takeda, et al, 2015;Wu et al, 2018;Zhang et al, 2012), because of scare measured data in Kuroshio. Therefore, contributions of filamentous cyanobacteria and unicellular diazotrophs to N 2 fixation in the ECS remain unclear, and direct measurement of size-fractioned N 2 fixation is required.…”

Section: Estimation Of N 2 Fixation By Filamentous Diazotrophs Duringmentioning

confidence: 93%

“…Like buoyant Trichodesmium , diatom–diazotroph associations (DDAs) have an important role in carbon sequestration and in the biological pump because of their heavy, silicon‐containing cell walls (Brzezinski et al, ; Karl et al, ; Subramaniam et al, ; White et al, ). Under the drastic increase in p CO 2 and sea surface temperature (SST), the distribution, controlling factors, and N 2 fixation of Trichodesmium and Richelia / Calothrix are receiving greater interest (Sohm, Webb, & Capone, ; Subramaniam et al, ; Wu et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, Kuroshio and its branches strongly intrude into the ECS and SYS (ECSYS), which profoundly influence the physicochemical environment and biogeochemical processes (Chen, 2009;Zhang et al, 2007). N 2 fixation rates (NFRs) in Kuroshio and adjacent waters Shiozaki et al, 2010;Wu et al, 2018;Zhang et al, 2012) were found to be higher than those reported in most global seas (Landolfi et al, 2018;Luo et al, 2012;Tang et al, 2019). Kuroshio is recognized as the hotspot of N 2 fixation in the Pacific Ocean where fixed N contributes significant role in the N budget (Shiozaki et al, 2010;Shiozaki, Takeda, et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Kuroshio Shape Composition and Distribution of Filamentous Diazotrophs in the East China Sea and Southern Yellow Sea

et al. 2019

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The filamentous Trichodesmium and Richelia/Calothrix appear to be crucial N 2 -fixing cyanobacteria throughout the warm oligotrophic ocean, particularly in western boundary currents. The Kuroshio, the hotspot of N 2 fixation in the Pacific Ocean, intrudes into the East China Sea (ECS) and southern Yellow Sea (SYS), which may profoundly influence composition and distribution of filamentous diazotrophs. We provide high spatial resolution dataset of filamentous diazotrophs in the ECS and SYS in July and August 2013. Results showed that Trichodesmium colonies and Richelia/Calothrix were strictly restricted to warm, saline, nitrogen-limited waters of the ECS influenced by Kuroshio and were not detected in the SYS. The density of Trichodesmium in the ECS and SYS was 8.48 × 10 6 trichomes/m 2 , and colonial trichomes accounted for 40%. In addition to free filaments, Richelia/Calothrix were found to be symbiotic with diatoms Hemiaulus, Rhizosolenia/Guinardia, Chaetoceros, and Bacteriastrum with a total density at 2.13 × 10 6 heterocysts/m 2 in the ECS. The densities of filamentous diazotrophs were significantly higher in high-salinity region of the ECS (mainly controlled by Kuroshio) than in low-salinity region of the ECS and in the SYS. The densities of Trichodesmium and Richelia/Calothrix were significantly and positively correlated with temperature, salinity, and mixed-layer depth but were negatively correlated with NO 3 , turbidity, and chlorophyll-a. These results suggested that composition and distribution of filamentous diazotrophs in the ECS and SYS were largely shaped by Kuroshio and associated physicochemical properties. We hypothesize that active N 2 fixation in Kuroshio may be substantially supported by Richelia/Calothrix in addition to Trichodesmium.

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Section: Estimation Of N 2 Fixation By Filamentous Diazotrophs Duringmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kuroshio Shape Composition and Distribution of Filamentous Diazotrophs in the East China Sea and Southern Yellow Sea

et al. 2019

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“…The recent result obtained from a global survey of genes used for the assimilation of the organic compounds in picocyanobacteria directly indicated that the Synechococcus clade-II prefer to take up amino acids and NH 4 for use in biogenesis (Yelton et al 2016). During the study period in 2009, besides excretion of zooplankton, the diazotrophic cyanobacteria, Trichodesmium, usually thriving in the Kuroshio Current in summer, might provide considerable amount of NH 4 , (Chen et al 2008;Chung et al 2012;Wu et al 2018). Additionally, the study area is an excellent fishing ground, and the contribution of fish excrement to the organic nitrogen inventory cannot be ignored.…”

Section: Discussionmentioning

confidence: 99%

Attribution of the growth of a distinct population of Synechococcus to the coverage of lateral water on an upwelling

Chung¹,

Gong²

2019

Terr. Atmos. Ocean. Sci.

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Upwelling water generally transports abundant nutrients to fertilize the euphotic zone and promotes larger phytoplankton to thrive. In contrast, knowledge about the composition of prokaryotic picoplankton associated with the scale of upwelling is limited. In this study, the population compositions of prokaryotic picoplankton, with particular focus on Synechococcus, under two diverse hydrographic conditions in the shelf-margin upwelling system were compared in detail. During the study period of 2009, an upwelling event was observed. In contrast to conventional upwelled water, the surface of this upwelling was covered with a thin layer of nutrient-depleted water. Although the water exchange created a low-nutrient stock environment, which fell below traditional chemical detection limits, its flux was likely sufficient to support the growth of the Synechococcus clade-II lineage. In comparison with the hydrography in 2009, no obvious upwelling occurred, and oligotrophic water primarily occupied the upper layer during the study period of 2010. The abundance of Synechococcus significantly declined to approximately half its numbers observed in 2009. While the Synechococcus clade-II were still the predominant population, their proportion in the 16S rRNA gene library decreased to approximately 50%. The remaining part was replaced with α-Proteobacteria and various heterotrophic bacteria. The results of the present study, combined with those obtained in previous studies, yield a more comprehensive understanding of the phytoplankton community dynamics in this varied ecosystem.

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“…Trichodesmium is highly abundant in the Kuroshio Current (35,36), which directly flows through the KST area. Before the extreme events, cyanobacterial production in the KST area was suppressed by the high concentration of toxic metals such as arsenic, cadmium, copper and lead (37).…”

Section: Dietary Response To the Drastic Biogeochemical Changes And Hmentioning

confidence: 99%

Foraging strategies under extreme events: Contrasting adaptations by benthic macrofauna to drastic biogeochemical disturbance

Wang

Lebrato

Tseng

et al. 2020

Preprint

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Extreme events caused by global change are increasingly affecting the ocean’s biogeochemical cycling and ecosystem functioning, but it is challenging to observe how food webs respond to rapid habitat disturbances. Benthic communities are particularly vulnerable because their habitats are easily affected by extreme events. Here, we examined how benthic macrofauna responded to a “near shutdown” of shallow marine hydrothermal vents, triggered by M5.8 earthquake and C5 typhoon events. Despite reduced vent fluxes, we shows that the endemic vent crab Xenograpsus testudinatus continued to rely on chemosynthetic sulfur bacteria rather than photosynthetic sources. We posit this obligate nutritional dependence caused a population decline of vent crabs. In contrast, the non-endemic mollusks exhibited much greater dietary plasticity with no detectable impact on the population. Our study based on naturally occurring extreme events exemplifies how specialist species in marine system are particularly vulnerable to the unprecedented evolutionary and environmental pressures exerted by human activities worldwide.

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Nitrogen Fixation by Trichodesmium and unicellular diazotrophs in the northern South China Sea and the Kuroshio in summer

Cited by 35 publications

References 65 publications

Kuroshio Shape Composition and Distribution of Filamentous Diazotrophs in the East China Sea and Southern Yellow Sea

Kuroshio Shape Composition and Distribution of Filamentous Diazotrophs in the East China Sea and Southern Yellow Sea

Attribution of the growth of a distinct population of Synechococcus to the coverage of lateral water on an upwelling

Foraging strategies under extreme events: Contrasting adaptations by benthic macrofauna to drastic biogeochemical disturbance

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