Nitrate fluxes induced by turbulent mixing in dipole eddies in an oligotrophic ocean

Li, Ruihuan; Xu, Jie; Cen, Xian‐Rong; Zhong, Wanxuan; Liao, Jingsheng; Z, Shi; Zhou, Sheng‐Qi

doi:10.1002/lno.11794

Cited by 6 publications

(4 citation statements)

References 72 publications

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“…In the dipole eddies in western South China Sea, Li et al. (2021) quantified the vertical nitrate fluxes to the base of the euphotic zone in the same cruise and found that the turbulent nitrate flux at the base of the euphotic zone of CE was significantly higher than that of ACE and the new production in CE was mainly supported by upwelling. Wang et al.…”

Section: Discussionmentioning

confidence: 99%

Chromatic Acclimating Synechococcus Dominate in Mesoscale Eddies

Zhang,

Li,

et al. 2024

JGR Oceans

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Mesoscale eddies are found almost everywhere in global ocean. They can last for weeks to months with scales up to over 100 km and play important roles in global biogeochemical cycles. In this study, we analyzed the phylogenetic and pigment type composition of Synechococcus in a cyclonic eddy (CE, cold eddy) and an anticyclonic eddy (ACE, warm eddy) located in western South China Sea in summer, 2018. Nutrients pumping enhanced Synechococcus abundance markedly in the upper euphotic layers of CE. High diversity of both phylogenetic clades and pigment types of Synechococcus were discovered in the sampling area, with clear composition difference between CE and ACE. The chromatic acclimating pigment type (PT) 3dA dominated in CE while PT 3dB dominated in ACE. The potential weak chromatic acclimator PT 3eA contributed a significant proportion in both CE and ACE. To better understand the difference of PT composition in CE and ACE, we further investigated the phylogenetic composition of Synechococcus in CE and ACE. Clade CRD 1, which were the main strains in upwelling regions, were dominant in CE, where cooler and nutrient rich subsurface water was pumped to the upper layers. Warm water adapted clade II and clade III dominated in ACE. Our study, for the first time, indicated that chromatic acclimation was important in shaping the vertical profile of Synechococcus community in mesoscale eddies of the subtropical oceans.

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Section: Discussionmentioning

confidence: 99%

Chromatic Acclimating Synechococcus Dominate in Mesoscale Eddies

Zhang,

Li,

et al. 2024

JGR Oceans

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“…The most common manifestations of mesoscale eddies regulating the rates of biological processes are related to vertical movements which can affect the availability of both light and nutrients to phytoplankton and thereby alter the growth of phytoplankton (Cullen, 2015; Li et al., 2021). Mesoscale eddies affect phytoplankton distribution and hence Chl concentrations via different mechanisms, such as nutrient pumping associated with eddy intensification (Falkowski et al., 1991; McGillicuddy, 2016), diapycnal nutrient fluxes as a result of the steeper vertical gradients in inorganic nutrients caused by eddies (Barone et al., 2022) and the redistribution of nutrients in the euphotic zone due to eddy‐induced vertical oscillations of the pycnocline (Falkowski et al., 1991).…”

Section: Discussionmentioning

confidence: 99%

Mesoscale Eddy Modulation of Subsurface Chlorophyll Maximum Layers in the South China Sea

Xu,

Wang,

Cheng

et al. 2023

JGR Biogeosciences

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Subsurface chlorophyll maximum (SCM) layers contribute considerably to the integrated biomass of the water column and can be strongly modulated by mesoscale eddies that are ubiquitous in the global ocean. The mechanisms of eddy‐induced surface chlorophyll concentration have been extensively examined in the South China Sea (SCS). However, the potential impact of mesoscale eddies on SCM layers remains unclear. We examined the influence of mesoscale eddies on the depth, thickness and magnitude of SCM layers in the SCS using output from an eddy‐permitting biological–physical coupled model over a 22‐year period. Our study shows that nutrient distribution is largely driven by eddy dynamics, with cyclonic eddies enhancing the supply of inorganic nutrients in the upper layers by uplifting the thermocline, and downward displacement of the thermocline in anticyclonic eddies, reducing the nutrient supply into the euphotic zone from the depth. We found that anticyclonic (cyclonic) eddies are responsible for increased (decreased) SCM depth and decreased (increased) SCM magnitude; SCM thickness decreased in cyclonic eddies but slightly increased in anticyclonic eddies. The effects of mesoscale eddies depend on eddy amplitude. Maximal anomalies in depth, thickness and magnitude always occur near the center of eddies. Phytoplankton community structure at SCM layers is also affected by eddies, with more diatoms in cyclonic eddies and more coccolithophores in anticyclonic eddies. Our study will advance our understanding of mesoscale physical–biogeochemical interactions.

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“…Turbulence and shear enhance encounter rates of TEP precursor and coagulation of particles increasing their sizes (Beauvais et al, 2006;Pedrotti et al, 2010;Burns et al, 2019). Floating particles tend to gather in CEs's core due to horizontal shear instabilities promoting shear and spirals (Munk et al, 2000) and turbulence kinetics are higher at the center of the CEs due to upwelling (Li et al, 2021). Simultaneously, though, it is also expected that the increased frequency of collisions will facilitate more collisions amongst larger aggregates.…”

Section: Transparent Exopolymer Particles (Tep)mentioning

confidence: 99%

Distribution of polysaccharidic and proteinaceous gel−like particles in three cyclonic eddies in the Eastern Tropical North Atlantic

Devresse,

Becker,

Engel

2024

Front. Mar. Sci.

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Transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP), two prominent classes of gel−like particles in the ocean primarily produced by phytoplankton, play crucial roles in ecological and biogeochemical processes, influencing microbial nutrition, growth, and particle aggregation. The distribution of these particles is intricately linked to the spatiotemporal dynamics of phytoplankton. Mesoscale cyclonic eddies (CEs) are known to stimulate phytoplankton growth and influence particle transport, but their effects on TEP and CSP remain to be determined. In the Eastern Tropical North Atlantic (ETNA), we examined three CEs: one off the Mauritanian coast during summer (Mau), one offshore during winter (Sal), and another near Brava island during winter. Mau and Brava CEs were in their intensification/maturity phase, while the Sal CE was in its decay phase. Both TEP and CSP concentrations correlated with primary productivity, but TEP increased with chlorophyll−a concentration, whereas elevated CSP coincided also with the highest abundance of pico−nanophytoplankton (<20 µm), mainly Synechococcus. Both gels exhibited a positive correlation with bacterial biomass production, indicating their consumption by heterotrophic bacteria. TEP total area in the epipelagic waters of all CEs (Mau, Brava, and Sal) was elevated compared to surrounding waters, with on average 4, 2.5, and 1.6−fold higher values, respectively. However, no significant difference in TEP size distribution was observed within any CEs and their surroundings. Similarly, CSP total area increased in the epipelagic waters of Mau and Brava CEs, with on average 5 and 2.4−fold higher values, respectively, compared to surrounding waters. CSP particles were notably larger in these two eddies, while the Sal CE showed no significant difference from surrounding waters in CSP abundance and size. Overall, TEP and CSP exhibited distinct responses to CEs, with increased concentrations during their intensification/maturation stage and remineralization dominating during their decaying stage.

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Nitrate fluxes induced by turbulent mixing in dipole eddies in an oligotrophic ocean

Cited by 6 publications

References 72 publications

Chromatic Acclimating Synechococcus Dominate in Mesoscale Eddies

Chromatic Acclimating Synechococcus Dominate in Mesoscale Eddies

Mesoscale Eddy Modulation of Subsurface Chlorophyll Maximum Layers in the South China Sea

Distribution of polysaccharidic and proteinaceous gel−like particles in three cyclonic eddies in the Eastern Tropical North Atlantic

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