The contribution of aeolian sand and dust to iron fertilization of phytoplankton blooms in southwestern Ross Sea, Antarctica

Winton, V. Holly L.; Dunbar, Gavin B.; Bertler, Nancy A. N.; Millet, Marc-Alban; Delmonte, Barbara; Atkins, Cliff; Chewings, Jane Margaret; Andersson, Per

doi:10.1002/2013gb004574

Cited by 42 publications

(85 citation statements)

References 104 publications

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“…[], MEDUSA‐RS also does not include aeolian deposition. A sensitivity analysis revealed that realistic concentrations of atmospheric iron deposition in the Ross Sea negligibly affect the modeled phytoplankton, in accordance with field‐based estimates [ Winton et al ., ]. All model equations are provided in the supporting information Tables S1 and S2.…”

Section: Methodsmentioning

confidence: 99%

Climate change impacts on southern Ross Sea phytoplankton composition, productivity, and export

et al. 2017

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The Ross Sea, a highly productive region of the Southern Ocean, is expected to experience warming during the next century along with reduced summer sea ice concentrations and shallower mixed layers. This study investigates how these climatic changes may alter phytoplankton assemblage composition, primary productivity, and export. Glider measurements are used to force a one‐dimensional biogeochemical model, which includes diatoms and both solitary and colonial forms of Phaeocystis antarctica. Model performance is evaluated with glider observations, and experiments are conducted using projections of physical drivers for mid‐21st and late‐21st century. These scenarios reveal a 5% increase in primary productivity by midcentury and 14% by late‐century and a proportional increase in carbon export, which remains approximately 18% of primary production. In addition, scenario results indicate diatom biomass increases while P. antarctica biomass decreases in the first half of the 21st century. In the second half of the century, diatom biomass remains relatively constant and P. antarctica biomass increases. Additional scenarios examining the independent contributions of expected future changes (temperature, mixed layer depth, irradiance, and surface iron inputs from melting ice) demonstrate that earlier availability of low light due to reduction of sea ice early in the growing season is the primary driver of productivity increases over the next century; shallower mixed layer depths additionally contribute to changes of assemblage composition and export. This study further demonstrates how glider data can be effectively used to facilitate model development and simulation, and inform interpretation of biogeochemical observations in the context of climate change.

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Section: Methodsmentioning

confidence: 99%

Climate change impacts on southern Ross Sea phytoplankton composition, productivity, and export

et al. 2017

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“…The evidence supporting very small atmospheric dust Fe inputs has been well discussed elsewhere; atmospheric deposition is very likely to be insignificant relative to other fluxes to the euphotic zone (Sedwick et al 2011;Gerringa et al, 2012;Gao et al, 2013;Planquette et al, 2013), although aerosol concentrations have yet to be quantified in the ASP region. In other Antarctic regions with substantial exposed unconsolidated sediments on the proximal continent, dust sources may be somewhat more important (Winton et al, 2014).…”

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confidence: 99%

Dynamics of dissolved iron and other bioactive trace metals (Mn, Ni, Cu, Zn) in the Amundsen Sea Polynya, Antarctica

Sherrell

Lagerström

Forsch

et al. 2015

Elementa: Science of the Anthropocene

123

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The Amundsen Sea Polynya is experiencing large increases in glacial meltwater input and hosts an extremely productive and long-lasting summer phytoplankton bloom, suggesting a crucial role for natural Fe fertilization. Early summer distributions and dynamics of the dissolved bioactive metals Fe, Mn, Zn, Cu and Ni were investigated during a three week period in 2010-2011, using GEOTRACES-compliant methods. Dissolved Fe was very low (0.06-0.12 nmol kg −1 ) in the upper 20 m of the central polynya, suggesting that the sub-maximal rates of in situ primary productivity reported previously for this growth phase of the bloom are attributable to insufficient Fe availability. Weeks after the sampling period, phytoplankton biomass accumulated to peak bloom conditions, implying a continuous supply of bioavailable Fe to the euphotic zone. The dominant biologically-relevant Fe source was meltwater-enriched seawater flowing from the Dotson Ice Shelf cavity and delivering Fe at 0.7 nmol kg −1 to the broader polynya. The modest Fe content of Circumpolar Deep Water (CDW; 0.3 nmol kg −1 ), invading through cross-shelf troughs, was strongly augmented by benthic Fe inputs, which may combine with glacial meltwater dFe in the Dotson outflow. Sea ice melting provided a modest local Fe flux, insufficient to drive large annual blooms. Dissolved Mn was strongly reduced in surface waters, but displayed a subsurface maximum likely advected through the region from shallow coastal sediments. Nutrient-type elements Zn, Cu and Ni had large to small dynamic ranges, respectively, and increasing concentrations with depth, indicating uptake and remineralization within the polynya system. Surface water drawdown ratios of metals and nutrients provided novel estimates of metal quotas (metal/P) for the dominant bloom phytoplankton, Phaeocystis antarctica. At one unique mature bloom station, Zn and Cu were scavenged to low concentrations throughout the 350 m water column, a possible result of intense removal onto sinking Phaeocystis biodetritus. The Amundsen Sea appears to be a model region for studying the biogeochemical consequences of increased glacial meltwater inputs.

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“…, with locally higher deposition confined to the McMurdo Sound area [Winton et al, 2014]. Postconvective vertical mixing by turbulent diffusion and/or episodic upwelling by mesoscale and submesoscale fronts and eddies may supply additional dFe during the growing season.…”

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confidence: 99%

Iron supply and demand in an Antarctic shelf ecosystem

McGillicuddy

Sedwick

Dinniman

et al. 2015

Geophysical Research Letters

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The Ross Sea sustains a rich ecosystem and is the most productive sector of the Southern Ocean. Most of this production occurs within a polynya during the November–February period, when the availability of dissolved iron (dFe) is thought to exert the major control on phytoplankton growth. Here we combine new data on the distribution of dFe, high‐resolution model simulations of ice melt and regional circulation, and satellite‐based estimates of primary production to quantify iron supply and demand over the Ross Sea continental shelf. Our analysis suggests that the largest sources of dFe to the euphotic zone are wintertime mixing and melting sea ice, with a lesser input from intrusions of Circumpolar Deep Water and a small amount from melting glacial ice. Together these sources are in approximate balance with the annual biological dFe demand inferred from satellite‐based productivity algorithms, although both the supply and demand estimates have large uncertainties.

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The contribution of aeolian sand and dust to iron fertilization of phytoplankton blooms in southwestern Ross Sea, Antarctica

Cited by 42 publications

References 104 publications

Climate change impacts on southern Ross Sea phytoplankton composition, productivity, and export

Climate change impacts on southern Ross Sea phytoplankton composition, productivity, and export

Dynamics of dissolved iron and other bioactive trace metals (Mn, Ni, Cu, Zn) in the Amundsen Sea Polynya, Antarctica

Iron supply and demand in an Antarctic shelf ecosystem

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