Eddies Affect Subsurface Phytoplankton and Oxygen Distributions in the North Pacific Subtropical Gyre

Xiu, Peng; Chai, Fei

doi:10.1029/2020gl087037

Cited by 42 publications

(45 citation statements)

References 61 publications

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“…We could not detect the effects of meso-scale eddies on the micro-size plankton abundance (and also assemblages), whereas other studies [27][28][29] have reported that the phytoplankton abundance vary with the eddies. Several studies focused on the variations in chlorophyll a concentration, but micro-size plankton abundance and assemblages vary with meso-scale eddies, as reported by Davis and McGillicuddy [48].…”

Section: Plos Onecontrasting

confidence: 99%

“…As several previous studies have indicated that phytoplankton abundance and assemblages differ with the eddy structure (cyclonic or anticyclonic) in the open ocean [ 27 – 29 ], we used relative vorticity (Ro) as the index of the eddy structure. Ro is calculated from the following equations where ζ is absolute vorticity, and f is the Coriolis parameter.…”

Section: Methodsmentioning

confidence: 99%

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Micro-size plankton abundance and assemblages in the western North Pacific Subtropical Gyre under microscopic observation

et al. 2021

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While primary productivity in the oligotrophic North Pacific Subtropical Gyre (NPSG) is changing, the micro-size plankton community has not been evaluated in the last 4 decades, prompting a re-evaluation. We collected samples over three years (2016–2018) from depths of 10 to 200 m (n = 127), and the micro-size plankton were identified and counted to understand the heterogeneity of micro-size plankton community structure. The assemblages were consistent to the those of 4 decades ago. Dinophyceae (dinoflagellates) were the most numerically abundant, followed by Cryptophyceae and Bacillariophyceae (diatoms). The other micro-size plankton classes (Cyanophyceae, Haptophyceae, Dictyochophyceae, Euglenophyceae, and Prasinophyceae) were not always detected, whereas only Trichodesmium spp. was counted in the Cyanophyceae. Other unidentified autotrophic and heterotrophic flagellates were also significantly present, and their numeric abundance was higher than or at the same level as was that of the Dinophyceae. In the Dinophyceae, Gymnodiniaceae and Peridiniales were abundant. The chlorophyll a concentration and these class-level assemblages suggested micro-size plankton is not a major primary producer in this area. We applied generalized additive models (GAMs) and principal coordination analyses (PCoAs) to evaluate the habitats of every plankton group and the heterogeneity of the assemblages. The GAMs suggested that every classified plankton abundance showed a similar response to salinity, and we observed differences in habitats in terms of temperature and nitrate concentrations. Based on the PCoAs, we observed unique communities at the 200 m depth layer compared with those at the other sampling layers. The site scores of PCoAs indicated that the micro-size plankton assemblages are most heterogeneous at the 10 m depth layer. At such depth, diazotrophic Cyanophyceae (Trichodesmium spp.) are abundant, particularly in less-saline water. Therefore, nitrogen fixation may contribute to the heterogeneity in the abundance and assemblages in the western NPSG.

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Section: Plos Onecontrasting

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Micro-size plankton abundance and assemblages in the western North Pacific Subtropical Gyre under microscopic observation

et al. 2021

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“…However, nuances are increasingly reported in eddy mechanisms and associated phytoplankton responses, highlighting the complexity of the phenomena in play (e.g., variations in physical fields through the eddy lifetime, contribution of lateral exchanges, eddy‐wind interaction, submesoscale pumping, eddy‐eddy interaction: Guidi et al., 2012 ; Lévy et al., 2001 ; McGillicuddy et al., 2007 ; Siegel et al., 2013 ; Sweeney et al., 2003 ). Among those modulations, variations are observed between the core sector of the eddies and their edge, the latter being subject to significant vertical motions impacting submesocale filaments and implying interactions with the surroundings waters (Klein & Lapeyre, 2009 ; Siegel et al., 2008 ; Xiu & Chai, 2020 ). Moreover, the respective influences of C and AC on phytoplankton dynamics are still debated (Barone et al., 2019 ; Brannigan, 2016 ; Dufois et al., 2016 ; Xiu & Chai, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

“…Among those modulations, variations are observed between the core sector of the eddies and their edge, the latter being subject to significant vertical motions impacting submesocale filaments and implying interactions with the surroundings waters (Klein & Lapeyre, 2009 ; Siegel et al., 2008 ; Xiu & Chai, 2020 ). Moreover, the respective influences of C and AC on phytoplankton dynamics are still debated (Barone et al., 2019 ; Brannigan, 2016 ; Dufois et al., 2016 ; Xiu & Chai, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Impact of Mesoscale Eddies on Deep Chlorophyll Maxima

Cornec

Laxenaire

Claustre

et al. 2021

Geophysical Research Letters

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To better understand their dynamics, it is necessary to assess the drivers affecting their environmental properties, in particular, those affecting light and nutrient availability at depth. Small-scale ocean dynamics, such as internal waves or mesoscale eddies, may act as altering factors synced with phytoplankton responses, as they can induce vertical perturbations of the water column (McGillicuddy et al., 1998;Uz et al., 2001). Mesoscale eddies are ubiquitous structures in the global ocean (Chaigneau Abstract Deep Chlorophyll Maxima (DCM) are ubiquitous features in stratified oceanic systems.Their establishment and maintenance result from hydrographical stability favoring specific environmental conditions with respect to light and nutrient availability required for phytoplankton growth. This stability can potentially be challenged by mesoscale eddies impacting the water column's vertical structure and thus the environmental parameters that condition the subsistence of DCMs. Here, data from the global BGC-Argo float network are collocated with mesoscale eddies to explore their impact on DCMs. We show that cyclonic eddies, by providing optimal light and nutrient conditions, increase the occurrence of DCMs characterized by Deep Biomass Maxima for phytoplankton. In contrast, DCMs in anticyclonic eddies seem to be driven by photoacclimation as they coincide with Deep Acclimation Maxima without biomass accumulation. These findings suggest that the two types of eddies potentially have different impacts on the role of DCMs in global primary production. Plain Language SummaryIn the global ocean, phytoplankton can be found at depths where their growth is limited by their access to light from the surface and nutrient supply from below. Depending on the combination of environmental conditions, phytoplankton at depth can either accumulate in densely populated layers or deploy adaptive survival strategies such as multiplying their internal light sensors. Given their dependence on environmental variations, phytoplankton can be affected by physical disturbances that alter the vertical structure of the water column's properties. Among these are mesoscale eddies, large water structures dominated by rotation on the horizontal plane which also induce vertical physical movements. In this study, we associate data from autonomous robots that drift with ocean currents and sample physical and biological properties down to a depth of 2,000 meters, with mesoscale eddies detected by satellite. We show that on a global scale, cold mesoscale eddies promote the growth of phytoplankton at depth.

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“…Two reasons were considered for our results on the meso-scale eddies, namely 1) the difference in observation of oceanic basins, and 2) the limitations of our approach (observations and statistical models). First, previous studies had been conducted in the central and eastern NPSG [27][28][29], and the heterogeneity of plankton abundance and assemblages with the meso-scale eddies are observed rarely in the western NPSG. Second, our data sets were a mixture of observations of three cruises, of which the primary aims were investigation of the distribution of Japanese eel larvae.…”

Section: Plos Onementioning

confidence: 99%

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Eddies Affect Subsurface Phytoplankton and Oxygen Distributions in the North Pacific Subtropical Gyre

Cited by 42 publications

References 61 publications

Micro-size plankton abundance and assemblages in the western North Pacific Subtropical Gyre under microscopic observation

Micro-size plankton abundance and assemblages in the western North Pacific Subtropical Gyre under microscopic observation

Impact of Mesoscale Eddies on Deep Chlorophyll Maxima

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