Comparative roles of upwelling and glacial iron sources in Ryder Bay, coastal western Antarctic Peninsula

Annett, Amber; Skiba, Marta; Henley, Sian F.; Venables, Hugh J.; Meredith, Michael P.; Statham, Peter J.; Ganeshram, Raja S.

doi:10.1016/j.marchem.2015.06.017

Cited by 69 publications

(100 citation statements)

References 82 publications

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“…Although there are several potential sources of iron to surface waters (glacial melt, sea‐ice melt, seawater interaction with shallow sediments, atmospheric input and deep water upwelling), glacial meltwater has been identified as one of the most important [ Dierssen et al ., ; Hawkings et al ., ], by its volume flux and because of the continuous yet variable supply during the growing season [ Meredith et al ., ]. The close proximity of canyon head systems on the WAP to the coast where glaciers are prominent features, may also contribute favorably to the increased production seen in the canyon as the increased glacial meltwater input (and pushed by the coastal current) contributes to increased water column stability and is a potential source of iron to the system [ Alderkamp et al ., ; Annett et al ., ; Arrigo et al ., ]. While mUCDW upwelling enriched with iron from sediments has been proposed as a potential source of iron to coastal WAP regions [ Annett et al ., ], at Ryder Bay (340 km south of Palmer Deep) it was found to account for very little of the iron input due to the highly stratified waters during the growth season.…”

Section: Discussionmentioning

confidence: 99%

“…Macronutrients are generally abundant throughout the WAP [ Ducklow et al ., ; Serebrennikova and Fanning , ] and although they show marked seasonality [ Clarke et al ., ], in most cases they do not seem to limit phytoplankton growth [ Holm‐Hansen and Mitchell , ]. Micronutrients such as iron do not seem to limit primary production in the coastal waters of the WAP where canyon heads are located either [ Annett et al ., ; Helbling et al ., ; Martin et al ., ], but available data are limited.…”

Section: Introductionmentioning

confidence: 98%

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Mixing and phytoplankton dynamics in a submarine canyon in the West Antarctic Peninsula

et al. 2016

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Bathymetric depressions (canyons) exist along the West Antarctic Peninsula shelf and have been linked with increased phytoplankton biomass and sustained penguin colonies. However, the physical mechanisms driving this enhanced biomass are not well understood. Using a Slocum glider data set with over 25,000 water column profiles, we evaluate the relationship between mixed layer depth (MLD, estimated using the depth of maximum buoyancy frequency) and phytoplankton vertical distribution. We use the glider deployments in the Palmer Deep region to examine seasonal and across canyon variability. Throughout the season, the ML becomes warmer and saltier, as a result of vertical mixing and advection. Shallow ML and increased stratification due to sea ice melt are linked to higher chlorophyll concentrations. Deeper mixed layers, resulting from increased wind forcing, show decreased chlorophyll, suggesting the importance of light in regulating phytoplankton productivity. Spatial variations were found in the canyon head region where local physical water column properties were associated with different biological responses, reinforcing the importance of local canyon circulation in regulating phytoplankton distribution in the region. While the mechanism initially hypothesized to produce the observed increases in phytoplankton over the canyons was the intrusion of warm, nutrient enriched modified Upper Circumpolar Deep Water (mUCDW), our analysis suggests that ML dynamics are key to increased primary production over submarine canyons in the WAP.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Mixing and phytoplankton dynamics in a submarine canyon in the West Antarctic Peninsula

et al. 2016

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“…Meanwhile the model used by Misumi et al (2014) predicts an iron supply increase to highnutrient, low-chlorophyll (HNLC) surface waters by 2090, especially in the eastern equatorial Pacific, attributed by the authors to changes in the meridional overturning and gyrescale circulations that might intensify the advective supply of iron to surface waters. Furthermore, several authors (Annett et al, 2015;Bhatia et al, 2013;Hawkings et al, 2014;Raiswell et al, 2008Raiswell et al, , 2016 point out that both glacial and deep-water Fe sources may increase with continued climate warming due to Fe input from other sources, such as shelf sediments, meltwater, icebergs, rivers, surface water runoff and dust input.…”

Section: The Isa Method: How To Increase Artificial Iron Emissionsmentioning

confidence: 99%

Climate engineering by mimicking natural dust climate control: the iron salt aerosol method

et al. 2017

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Abstract. Power stations, ships and air traffic are among the most potent greenhouse gas emitters and are primarily responsible for global warming. Iron salt aerosols (ISAs), composed partly of iron and chloride, exert a cooling effect on climate in several ways. This article aims firstly to examine all direct and indirect natural climate cooling mechanisms driven by ISA tropospheric aerosol particles, showing their cooperation and interaction within the different environmental compartments. Secondly, it looks at a proposal to enhance the cooling effects of ISA in order to reach the optimistic target of the Paris climate agreement to limit the global temperature increase between 1.5 and 2 • C.Mineral dust played an important role during the glacial periods; by using mineral dust as a natural analogue tool and by mimicking the same method used in nature, the proposed ISA method might be able to reduce and stop climate warming. The first estimations made in this article show that by doubling the current natural iron emissions by ISA into the troposphere, i.e., by about 0.3 Tg Fe yr −1 , artificial ISA would enable the prevention or even reversal of global warming. The ISA method proposed integrates technical and economically feasible tools.

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“…As the summer approaches and temperatures increase, ice melt, solar heating, and reduced winds shoal the ML and phytoplankton experience high, and sometimes excessive, light (Alderkamp et al, ). Concurrently, coastal meteoric (glacial meltwater and precipitation) and offshore sea ice melt inputs provide a spatially heterogeneous dFe supply that can continue to fuel some phytoplankton growth (Annett et al, , ). Surface ML light is expected to change in the future as upper ocean circulation, stratification, and sea ice cover continue to undergo rapid and dramatic changes (Martinson et al, ; Meredith et al, ; Moffat & Meredith, ; Schofield et al, ; Stammerjohn et al, ).…”

Section: Introductionmentioning

confidence: 99%

Light Is the Primary Driver of Early Season Phytoplankton Production Along the Western Antarctic Peninsula

et al. 2019

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Light and dissolved iron (dFe) availability control net primary production (NPP) in much of the Southern Ocean, but the primary controller during spring in the western Antarctic Peninsula has never been assessed. Underwater light and dFe availability are sensitive to climate‐induced changes in upper ocean circulation, stratification, and sea ice cover, which can affect NPP and phytoplankton community composition, both of which can alter carbon drawdown and food web structure. We estimated in situ NPP, net community production, and heterotrophic respiration and contextualized our field measurements with satellite‐based historical NPP estimates. Average light exposure mainly controlled NPP, while low dFe was associated with greatest NPP, indicating that spring phytoplankton growth is light‐limited and not dFe‐limited. Using experiments that simulated varying mixed layer depths by exposing phytoplankton to a short period of in situ surface light (up to 150× the mean light in the mixed layer, comparable to the difference in light experienced by phytoplankton mixed from 50 m to the surface), we assessed the effect of phytoplankton photoacclimation on NPP and relative success of individual taxa. At moderate light exposure (<30×), phytoplankton experienced little photodamage or changes in NPP, and Phaeocystis antarctica grew more than diatoms. Conversely, phytoplankton exposed to high light (>60×) experienced significant photodamage, declines in NPP, and declines in P. antarctica, with no consistent changes in diatoms. These results support the idea that P. antarctica is better adapted to variable light than diatoms and suggest that deeper mixed layers with variable light will favor P. antarctica.

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Comparative roles of upwelling and glacial iron sources in Ryder Bay, coastal western Antarctic Peninsula

Cited by 69 publications

References 82 publications

Mixing and phytoplankton dynamics in a submarine canyon in the West Antarctic Peninsula

Mixing and phytoplankton dynamics in a submarine canyon in the West Antarctic Peninsula

Climate engineering by mimicking natural dust climate control: the iron salt aerosol method

Light Is the Primary Driver of Early Season Phytoplankton Production Along the Western Antarctic Peninsula

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