Biogeochemical Dynamics in Adjacent Mesoscale Eddies of Opposite Polarity

Benedetto Barone; Matthew J. Church; Mathilde Dugenne; Nicholas J. Hawco; Oliver Jahn; Angelicque E. White; Seth G. John; Michael J. Follows; Edward F. DeLong; David M. Karl

doi:10.1029/2021GB007115

Biogeochemical Dynamics in Adjacent Mesoscale Eddies of Opposite Polarity

Benedetto Barone, Matthew J. Church, Mathilde Dugenne, Nicholas J. Hawco, Oliver Jahn, Angelicque E. White, Seth G. John, Michael J. Follows, Edward F. DeLong, David M. Karl

Flathead Lake Biological Station

Research output: Contribution to journal › Article › peer-review

24 Scopus citations

Abstract

We examined the biogeochemical impact of paired mesoscale cyclones and anticyclones in spatial proximity (<200 km apart) in the North Pacific Subtropical Gyre. While previous studies have demonstrated that upwelling associated with the intensification of cyclonic eddies can supply nutrients supporting plankton productivity, we observed that steeper vertical gradients in inorganic nutrients increased nutrient fluxes due to diapycnal mixing during the mature stage of cyclonic eddies. The increased diapycnal nutrient supply was linked with expansion of eukaryotic phytoplankton biomass and intensification of the deep chlorophyll maximum (DCM) layer. This perturbation in the plankton community was associated with increased fluxes of biominerals (specifically particulate inorganic carbon and particulate silica) and isotopically enriched organic nitrogen in particles exported in the cyclone. The time-integrated effects of thermocline vertical displacements on the lower euphotic zone were predictable deficits and surpluses of inorganic nutrients and dissolved oxygen, respectively. However, the stoichiometry of oxygen and inorganic nutrients differed from that predicted for production and consumption of phytoplankton biomass, requiring additional biological processes that decouple changes in oxygen and nutrient concentrations. The dynamics revealed by this study may be a common feature of oligotrophic ecosystems, where mesoscale biogeochemical perturbations are buffered by the DCM layer, which limits the ecological impact of eddies in the well-lit, near-surface ocean.

Original language	English
Article number	e2021GB007115
Journal	Global Biogeochemical Cycles
Volume	36
Issue number	2
DOIs	https://doi.org/10.1029/2021GB007115
State	Published - Feb 2022

Funding

We warmly thank Tara Clemente (University of Hawaii) for her leadership during the HOE‐Legacy 4 and MESO‐SCOPE expeditions. We are also grateful to Tim Burrell, Eric Shimabukuro, and Ryan Tabata (University of Hawaii) for their tireless efforts during field operations. We are grateful to Joshua Weitz and David Demory (Georgia Institute of Technology) for their thoughtful comments on the manuscript. We thank Susan Curless, Eric Grabowski, and Alexa Nelson (University of Hawaii) for the analysis of inorganic nutrients and sinking particle fluxes. The isotopic composition of nitrogen of sinking particles was measured by the Biogeochemical Stable Isotope Facility (University of Hawaii). This work was supported by grants from the Simons Foundation (#329108 to DMK, EFD, MJF, MJC, AEW, SGJ; 721252 to DMK; 721223 to EFD; 721221 to MJC; 721256 to AEW; 721250 to SGJ). We warmly thank Tara Clemente (University of Hawaii) for her leadership during the HOE-Legacy 4 and MESO-SCOPE expeditions. We are also grateful to Tim Burrell, Eric Shimabukuro, and Ryan Tabata (University of Hawaii) for their tireless efforts during field operations. We are grateful to Joshua Weitz and David Demory (Georgia Institute of Technology) for their thoughtful comments on the manuscript. We thank Susan Curless, Eric Grabowski, and Alexa Nelson (University of Hawaii) for the analysis of inorganic nutrients and sinking particle fluxes. The isotopic composition of nitrogen of sinking particles was measured by the Biogeochemical Stable Isotope Facility (University of Hawaii). This work was supported by grants from the Simons Foundation (#329108 to DMK, EFD, MJF, MJC, AEW, SGJ; 721252 to DMK; 721223 to EFD; 721221 to MJC; 721256 to AEW; 721250 to SGJ).

Funders	Funder number
Simons Foundation	721250, 721221, 721252, 329108, 721223, 721256

Keywords

chemical wake
deep chlorophyll maximum
diapycnal mixing
mesoscale eddy
nutrient injection

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10.1029/2021GB007115

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title = "Biogeochemical Dynamics in Adjacent Mesoscale Eddies of Opposite Polarity",

abstract = "We examined the biogeochemical impact of paired mesoscale cyclones and anticyclones in spatial proximity (<200 km apart) in the North Pacific Subtropical Gyre. While previous studies have demonstrated that upwelling associated with the intensification of cyclonic eddies can supply nutrients supporting plankton productivity, we observed that steeper vertical gradients in inorganic nutrients increased nutrient fluxes due to diapycnal mixing during the mature stage of cyclonic eddies. The increased diapycnal nutrient supply was linked with expansion of eukaryotic phytoplankton biomass and intensification of the deep chlorophyll maximum (DCM) layer. This perturbation in the plankton community was associated with increased fluxes of biominerals (specifically particulate inorganic carbon and particulate silica) and isotopically enriched organic nitrogen in particles exported in the cyclone. The time-integrated effects of thermocline vertical displacements on the lower euphotic zone were predictable deficits and surpluses of inorganic nutrients and dissolved oxygen, respectively. However, the stoichiometry of oxygen and inorganic nutrients differed from that predicted for production and consumption of phytoplankton biomass, requiring additional biological processes that decouple changes in oxygen and nutrient concentrations. The dynamics revealed by this study may be a common feature of oligotrophic ecosystems, where mesoscale biogeochemical perturbations are buffered by the DCM layer, which limits the ecological impact of eddies in the well-lit, near-surface ocean.",

keywords = "chemical wake, deep chlorophyll maximum, diapycnal mixing, mesoscale eddy, nutrient injection",

author = "Benedetto Barone and Church, \{Matthew J.\} and Mathilde Dugenne and Hawco, \{Nicholas J.\} and Oliver Jahn and White, \{Angelicque E.\} and John, \{Seth G.\} and Follows, \{Michael J.\} and DeLong, \{Edward F.\} and Karl, \{David M.\}",

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year = "2022",

month = feb,

doi = "10.1029/2021GB007115",

language = "English",

volume = "36",

journal = "Global Biogeochemical Cycles",

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T1 - Biogeochemical Dynamics in Adjacent Mesoscale Eddies of Opposite Polarity

AU - Barone, Benedetto

AU - Church, Matthew J.

AU - Dugenne, Mathilde

AU - Hawco, Nicholas J.

AU - Jahn, Oliver

AU - White, Angelicque E.

AU - John, Seth G.

AU - Follows, Michael J.

AU - DeLong, Edward F.

AU - Karl, David M.

PY - 2022/2

Y1 - 2022/2

N2 - We examined the biogeochemical impact of paired mesoscale cyclones and anticyclones in spatial proximity (<200 km apart) in the North Pacific Subtropical Gyre. While previous studies have demonstrated that upwelling associated with the intensification of cyclonic eddies can supply nutrients supporting plankton productivity, we observed that steeper vertical gradients in inorganic nutrients increased nutrient fluxes due to diapycnal mixing during the mature stage of cyclonic eddies. The increased diapycnal nutrient supply was linked with expansion of eukaryotic phytoplankton biomass and intensification of the deep chlorophyll maximum (DCM) layer. This perturbation in the plankton community was associated with increased fluxes of biominerals (specifically particulate inorganic carbon and particulate silica) and isotopically enriched organic nitrogen in particles exported in the cyclone. The time-integrated effects of thermocline vertical displacements on the lower euphotic zone were predictable deficits and surpluses of inorganic nutrients and dissolved oxygen, respectively. However, the stoichiometry of oxygen and inorganic nutrients differed from that predicted for production and consumption of phytoplankton biomass, requiring additional biological processes that decouple changes in oxygen and nutrient concentrations. The dynamics revealed by this study may be a common feature of oligotrophic ecosystems, where mesoscale biogeochemical perturbations are buffered by the DCM layer, which limits the ecological impact of eddies in the well-lit, near-surface ocean.

AB - We examined the biogeochemical impact of paired mesoscale cyclones and anticyclones in spatial proximity (<200 km apart) in the North Pacific Subtropical Gyre. While previous studies have demonstrated that upwelling associated with the intensification of cyclonic eddies can supply nutrients supporting plankton productivity, we observed that steeper vertical gradients in inorganic nutrients increased nutrient fluxes due to diapycnal mixing during the mature stage of cyclonic eddies. The increased diapycnal nutrient supply was linked with expansion of eukaryotic phytoplankton biomass and intensification of the deep chlorophyll maximum (DCM) layer. This perturbation in the plankton community was associated with increased fluxes of biominerals (specifically particulate inorganic carbon and particulate silica) and isotopically enriched organic nitrogen in particles exported in the cyclone. The time-integrated effects of thermocline vertical displacements on the lower euphotic zone were predictable deficits and surpluses of inorganic nutrients and dissolved oxygen, respectively. However, the stoichiometry of oxygen and inorganic nutrients differed from that predicted for production and consumption of phytoplankton biomass, requiring additional biological processes that decouple changes in oxygen and nutrient concentrations. The dynamics revealed by this study may be a common feature of oligotrophic ecosystems, where mesoscale biogeochemical perturbations are buffered by the DCM layer, which limits the ecological impact of eddies in the well-lit, near-surface ocean.

KW - chemical wake

KW - deep chlorophyll maximum

KW - diapycnal mixing

KW - mesoscale eddy

KW - nutrient injection

UR - https://www.scopus.com/pages/publications/85125132757

U2 - 10.1029/2021GB007115

DO - 10.1029/2021GB007115

M3 - Article

AN - SCOPUS:85125132757

SN - 0886-6236

VL - 36

JO - Global Biogeochemical Cycles

JF - Global Biogeochemical Cycles

IS - 2

M1 - e2021GB007115

ER -

Biogeochemical Dynamics in Adjacent Mesoscale Eddies of Opposite Polarity

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