Distribution of dissolved iron during the natural iron-fertilization experiment KEOPS (Kerguelen Plateau, Southern Ocean)

Blain, Stéphane; Sarthou, Géraldine; Laan, Patrick

doi:10.1016/j.dsr2.2007.12.028

Cited by 147 publications

(152 citation statements)

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“…Additionally, this species has been shown to be tolerant to low iron concentration (Brand et al, 1983;Sunda and Huntsman, 1995;Muggli and Harrison, 1997;Findlay and Giraudeau, 2000;Holligan et al, 2010). In January, the silicic acid concentration at the station A3 reaches o2 mmol L À 1 and iron concentration is $ 0.1 nmol L À 1 (Blain et al, 2008). Moreover, the high nitrate, phosphate and ammonium concentrations and the highest SST in late summer might be favorable conditions for a E. huxleyi bloom.…”

Section: Seasonality and Magnitude Of The Coccolith Fine Fraction Exportmentioning

confidence: 99%

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Rembauville

Meilland

Ziveri

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tWe report the contribution of planktic foraminifers and coccoliths to the particulate inorganic carbon (PIC) export fluxes collected over an annual cycle (October 2011/September 2012) on the central Kerguelen Plateau in the Antarctic Zone (AAZ) south of the Polar Front (PF). The seasonality of PIC flux was decoupled from surface chlorophyll a concentration and particulate organic carbon (POC) fluxes and was characterized by a late summer (February) maximum. This peak was concomitant with the highest satellite-derived sea surface PIC and corresponded to a Emiliania huxleyi coccoliths export event that accounted for 85% of the annual PIC export. The foraminifer contribution to the annual PIC flux was much lower (15%) and dominated by Turborotalita quinqueloba and Neogloboquadrina pachyderma. Foraminifer export fluxes were closely related to the surface chlorophyll a concentration, suggesting food availability as an important factor regulating the foraminifer's biomass. We compared size-normalized test weight (SNW) of the foraminifers with previously published SNW from the Crozet Islands using the same methodology and found no significant difference in SNW between sites for a given species. However, the SNW was significantly species-specific with a threefold increase from T. quinqueloba to Globigerina bulloides. The annual PIC:POC molar ratio of 0.07 was close to the mean ratio for the global ocean and lead to a low carbonate counter pump effect ( $ 5%) compared to a previous study north of the PF (6-32%). We suggest that lowers counter pump effect south of the PF despite similar productivity levels is due to a dominance of coccoliths in the PIC fluxes and a difference in the foraminifers species assemblage with a predominance of polar species with lower SNW.

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Section: Seasonality and Magnitude Of The Coccolith Fine Fraction Exportmentioning

confidence: 99%

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Rembauville

Meilland

Ziveri

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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“…Other trace elements, such as dissolved REE, radium isotopes and total dissolvable Fe, exhibit their highest concentrations at C01, indicative of a nearby lithogenic source (Blain et al, 2008b;van Beek et al, 2008;Zhang et al, 2008;Chever et al, 2010). Furthermore, the dissolved neodymium (Nd) isotopic composition at C01 (−6 ≤ ε Nd ≤ −4; Fig.…”

Section: Evidence Of a Lithogenic Source In The Vicinity Of Heard Islandmentioning

confidence: 99%

“…Indeed, this hypothesis was first raised by indirect geochemical tracers: rare earth element (REE) concentrations and radium activities strongly suggested that lateral advection of lithogenic materials weathered from Heard Island could be an important source of dissolved Fe (DFe) for the water surrounding the plateau (van Beek et al, 2008;Zhang et al, 2008). Also, regeneration from sinking biogenic materials and input from bottom sediments have been proposed as important processes generating high DFe in the deeper waters below 150 m over the plateau (Blain et al, 2008b). Park et al (2008b) suggested that diapycnal mixing enhanced by internal tides and convective winter mixing constitute the dominant mechanisms that make the deep Fe available for phytoplankton in surface waters in austral spring and summer.…”

Section: Introductionmentioning

confidence: 99%

Imprint of a dissolved cobalt basaltic source on the Kerguelen Plateau

et al. 2012

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Abstract. Processes of cobalt (Co) entrainment from shelf sediments over the Kerguelen Plateau were studied during the KEOPS (Kerguelen Ocean Plateau compared Study) in order to explain the exceptionally high dissolved cobalt concentrations that have been measured in the surface waters above the Kerguelen Plateau, and in intermediate and deep waters above its eastern slope. Lateral advection and dissolution of Co contained in basalt sediments around Heard Island, a main source of lithogenic Co in the study area, were shown to imprint the process of surface enrichment over the plateau. Dissolved Co enrichment was strongest at the intercept of the eastern slope with intermediate and deep waters, probably due to more efficient mobilisation of the sediments in the slope current, in addition to advection of Co-enriched and low-oxygenated ocean water masses.In surface waters, the strong sedimentary Co inputs were estimated to be much higher than biological Co uptake in phytoplankton blooms, underlining the potential use of dissolved cobalt as tracer of the natural iron fertilization above the Kerguelen Plateau. Based on a simple steady-state balance equation of the external input of dissolved iron over the plateau, the fertilization of iron inferred by using dissolved Co as a tracer of basalt sources is estimated to be 28 × 10 2 ± 21 × 10 2 t yr −1 in surface waters of the Kerguelen Plateau. This estimate is consistent with preceding ones (Zhang et al., 2008;Chever et al., 2010), and the calculated iron supply matches with the phytoplankton demand (Sarthou et al., 2008).

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“…Biological net community production, NCP, decreases sea surface pCO 2 . In high-nutrient, low-chlorophyll (HNLC) regions , including the Southern Ocean, more than 2 decades of intense research have confirmed that increasing iron supply stimulates primary production (Boyd et al, 2007;Blain et al, 2008). Large and persistent phytoplankton blooms develop annually in the vicinity of subantarctic islands Borrione and Schlitzer, 2013;Pollard et al, 2009) due to natural iron supply.…”

Section: Introductionmentioning

confidence: 99%

Carbon, oxygen and biological productivity in the Southern Ocean in and out the Kerguelen plume: CARIOCA drifter results

2015

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Distribution of dissolved iron during the natural iron-fertilization experiment KEOPS (Kerguelen Plateau, Southern Ocean)

Cited by 147 publications

References 50 publications

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Imprint of a dissolved cobalt basaltic source on the Kerguelen Plateau

Carbon, oxygen and biological productivity in the Southern Ocean in and out the Kerguelen plume: CARIOCA drifter results

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