On the relationship between fronts of the Antarctic Circumpolar Current and surface chlorophyll concentrations in the Southern Ocean

Sokolov, Serguei; Rintoul, Stephen R.

doi:10.1029/2006jc004072

Cited by 200 publications

(231 citation statements)

References 41 publications

Supporting

Mentioning

211

Contrasting

Unclassified

Order By: Relevance

“…1): (i) over the south-eastern Kerguelen Plateau, remarkably constrained by the bathymetry, (ii) in a plume extending eastward through the interaction between the polar front jet, crossing the plateau in a narrow mid-depth channel just to the south of the Kerguelen Island, and the rise bordering the basin to the north, (iii) and to the easternmost part of the study area in a zone of retroflection of the polar front and of eddy mixing between Antarctic and subantarctic surface waters (see Park et al, 2014). This complex distribution is in agreement with an input of iron from the interaction between the iron-deficient Antarctic Circumpolar Current and the local bathymetry Sokolov and Rintoul, 2007). Trace metals, and iron in particular, are required for many important cellular processes such as photosynthesis (including photoadaptation), respiration, and nitrate reduction.…”

Section: High Primary Production In Naturally Iron-fertilized Bloomssupporting

confidence: 62%

Production regime and associated N cycling in the vicinity of Kerguelen Island, Southern Ocean

et al. 2015

View full text Add to dashboard Cite

Abstract. Although the Southern Ocean is considered a high-nutrient, low-chlorophyll (HNLC) area, massive and recurrent blooms are observed over and downstream of the Kerguelen Plateau. This mosaic of blooms is triggered by a higher iron supply resulting from the interaction between the Antarctic Circumpolar Current and the local bathymetry. Net primary production, N uptake (NO − 3 and NH + 4 ), and nitrification rates were measured at eight stations in austral spring 2011 (October-November) during the KEOPS 2 cruise in the Kerguelen Plateau area. Natural iron fertilization stimulated primary production, with mixed layer integrated net primary production and growth rates much higher in the fertilized areas (up to 315 mmol C m −2 d −1 and up to 0.31 d −1 respectively) compared to the HNLC reference site (12 mmol C m −2 d −1 and 0.06 d −1 respectively). Primary production was mainly sustained by nitrate uptake, with f ratios (corresponding to NO − 3 -uptake / (NO − 3 -uptake + NH + 4 -uptake)) lying at the upper end of the observations for the Southern Ocean (up to 0.9). We report high rates of nitrification (up to ∼ 3 µmol N L −1 d −1 , with ∼ 90 % of them < 1 µmol N L −1 d −1 ) typically occurring below the euphotic zone, as classically observed in the global ocean. The specificity of the studied area is that at most of the stations, the euphotic layer was shallower than the mixed layer, implying that nitrifiers can efficiently compete with phytoplankton for the ammonium produced by remineralization at low-light intensities. Nitrate produced by nitrification in the mixed layer below the euphotic zone is easily supplied to the euphotic zone waters above, and nitrification sustained 70 ± 30 % of the nitrate uptake in the productive area above the Kerguelen Plateau. This complicates estimations of new production as potentially exportable production. We conclude that high productivity in deep mixing system stimulates the N cycle by increasing both assimilation and regeneration.

show abstract

Section: High Primary Production In Naturally Iron-fertilized Bloomssupporting

confidence: 62%

Production regime and associated N cycling in the vicinity of Kerguelen Island, Southern Ocean

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Ishikawa et al, 2002), however, large, lightly silicified diatoms can also occur . There are some exceptions in the POOZ, such as the Antarctic Polar Front (PF), in the lee of islands or where bottom topography enriches surface waters with iron, that are able to sustain larger, often heavily silicified phytoplankton in relatively high concentrations (Sokolov and Rintoul, 2007).…”

Section: Southern Ocean Primary Productivitymentioning

confidence: 99%

Southern Ocean phytoplankton physiology in a changing climate

Petrou

Kranz

Trimborn

et al. 2016

Journal of Plant Physiology

113

View full text Add to dashboard Cite

Please cite this article in press as: Petrou, K., et al., Southern Ocean phytoplankton physiology in a changing climate. J Plant Physiol (2016), http://dx.doi.org/10.1016/j.jplph.2016.05.004 ARTICLE IN PRESS a b s t r a c tThe Southern Ocean (SO) is a major sink for anthropogenic atmospheric carbon dioxide (CO 2 ), potentially harbouring even greater potential for additional sequestration of CO 2 through enhanced phytoplankton productivity. In the SO, primary productivity is primarily driven by bottom up processes (physical and chemical conditions) which are spatially and temporally heterogeneous. Due to a paucity of trace metals (such as iron) and high variability in light, much of the SO is characterised by an ecological paradox of high macronutrient concentrations yet uncharacteristically low chlorophyll concentrations. It is expected that with increased anthropogenic CO 2 emissions and the coincident warming, the major physical and chemical process that govern the SO will alter, influencing the biological capacity and functioning of the ecosystem. This review focuses on the SO primary producers and the bottom up processes that underpin their health and productivity. It looks at the major physico-chemical drivers of change in the SO, and based on current physiological knowledge, explores how these changes will likely manifest in phytoplankton, specifically, what are the physiological changes and floristic shifts that are likely to ensue and how this may translate into changes in the carbon sink capacity, net primary productivity and functionality of the SO.

show abstract

“…The nPF has a highly variable position as a function of longitude, so we derived the nPF using maps of absolute dynamic topography, which is the sum of satellite altimetry anomaly data and a mean dynamic topography (Rio and Hernandez, 2004). The nPF is defined using a constant isoline of sea surface height, using a technique first described by Sokolov and Rintoul (2007) (for more details see Swart and Speich, 2010). By analysing the time series of nPF positions between 1998-2008, we determined that the temporal variability in the nPF at each point in longitude, relative to the mean position used here, to be only 0.72°± 0.35.…”

Section: Methodsmentioning

confidence: 99%

A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean

et al. 2012

View full text Add to dashboard Cite

Abstract. Due to its importance as a limiting nutrient for phytoplankton growth in large regions of the world's oceans, ocean water column observations of concentration of the trace-metal iron (Fe) have increased markedly over recent decades. Here we compile >13 000 global measurements of dissolved Fe (dFe) and make this available to the community. We then conduct a synthesis study focussed on the Southern Ocean, where dFe plays a fundamental role in governing the carbon cycle, using four regions, six basins and five depth intervals as a framework. Our analysis highlights depth-dependent trends in the properties of dFe between different regions and basins. In general, surface dFe is highest in the Atlantic basin and the Antarctic region. While attributing drivers to these patterns is uncertain, inter-basin patterns in surface dFe might be linked to differing degrees of dFe inputs, while variability in biological consumption between regions covaries with the associated surface dFe differences. Opposite to the surface, dFe concentrations at depth are typically higher in the Indian basin and the Subantarctic region. The inter-region trends can be reconciled with similar ligand variability (although only from one cruise), and the inter-basin difference might be explained by differences in hydrothermal inputs suggested by modelling studies ) that await observational confirmation. We find that even in regions where many dFe measurements exist, the processes governing the seasonal evolution of dFe remain enigmatic, suggesting that, aside from broad Subantarctic -Antarctic trends, biological consumption might not be the major driver of dFe variability. This highlights the apparent importance of other processes such as exogenous inputs, physical transport/mixing or dFe recycling processes. Nevertheless, missing measurements during key seasonal transitions make it difficult to better quantify and understand surface water replenishment processes and the seasonal Fe cycle. Finally, we detail the degree of seasonal coverage by region, basin and depth. By synthesising prior measurements, we suggest a role for different processes and highlight key gaps in understanding, which we hope can help structure future research efforts in the Southern Ocean.

show abstract

On the relationship between fronts of the Antarctic Circumpolar Current and surface chlorophyll concentrations in the Southern Ocean

Cited by 200 publications

References 41 publications

Production regime and associated N cycling in the vicinity of Kerguelen Island, Southern Ocean

Production regime and associated N cycling in the vicinity of Kerguelen Island, Southern Ocean

Southern Ocean phytoplankton physiology in a changing climate

A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean

Contact Info

Product

Resources

About