Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean

Ardelan, Murat Van; Holm‐Hansen, Osmund; Hewes, Christopher D.; Reiss, Christian S.; Silva, N. S.; Dulai, Henrietta; Steinnes, E.; Sakshaug, Egil

doi:10.5194/bg-7-11-2010

Cited by 115 publications

(77 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As previously measured around South Georgia (Nielsdóttir et al, 2012, Holeton et al, 2005, but also in other regions of the Southern Ocean (e.g. Ardelan et al, 2010;Bucciarelli et al, 2001;Planquette et al, 2007), the model depicts highest dFe concentrations in near-shore waters (> 5 nM), decreasing with distance from the island. Our model results clearly show that the South Georgia island mass effect can reach regions located far away from the island (> 1000 km), where dFe concentrations may still be above background concentrations.…”

Section: The South Georgia Island Mass Effectsupporting

confidence: 51%

“…As shown in our model results around South Georgia (Fig. 9a) and by Ardelan et al (2010) and Planquette et al (2007) from in situ estimates, dFe scale lengths are variable and dependant on the direction and speed of local circulation. Clearly, it is important to keep in mind that scale length values do not depend on surface circulation only, but can be influenced by all processes that decrease or increase dFe concentrations between the source region and the points where scale lengths are measured (i.e.…”

Section: The South Georgia Island Mass Effectmentioning

confidence: 88%

“…These values include the wide range of scale lengths obtained from in situ dFe observations in the open ocean and near-shore regions of the Southern Ocean. Smallest values were obtained by Ardelan et al (2010) around the Antarctic Peninsula, and by Planquette et al (2007) around the Crozet Islands (∼ 25 km in both studies); larger-scale lengths were calculated around South Georgia by Nielsdóttir et al (2012) and in the vicinity of the Kerguelen Islands by Bucciarelli et al (2001) (scale lengths respectively 102 km and 151 km). As shown in our model results around South Georgia (Fig.…”

Section: The South Georgia Island Mass Effectmentioning

confidence: 99%

See 2 more Smart Citations

Sedimentary and atmospheric sources of iron around South Georgia, Southern Ocean: a modelling perspective

et al. 2014

View full text Add to dashboard Cite

Abstract. In high-nutrient low-chlorophyll waters of the western Atlantic sector of the Southern Ocean, an intense phytoplankton bloom is observed annually north of South Georgia. Multiple sources, including shallow sediments and atmospheric dust deposition, are thought to introduce iron to the region. However, the relative importance of each source is still unclear, owing in part to the scarcity of dissolved iron (dFe) measurements in the South Georgia region. In this study, we combine results from a recently published dFe data set around South Georgia with a coupled regional hydrodynamic and biogeochemical model to further investigate iron supply around the island. The biogeochemical component of the model includes an iron cycle, where sediments and dust deposition are the sources of iron to the ocean. The model captures the characteristic flow patterns around South Georgia, hence simulating a large phytoplankton bloom to the north (i.e. downstream) of the island. Modelled dFe concentrations agree well with observations (mean difference and root mean square errors of ∼ 0.02 nM and ∼ 0.81 nM) and form a large plume to the north of the island that extends eastwards for more than 800 km. In agreement with observations, highest dFe concentrations are located along the coast and decrease with distance from the island. Sensitivity tests indicate that most of the iron measured in the main bloom area originates from the coast and very shallow shelf-sediments (depths < 20 m). Dust deposition exerts almost no effect on surface chlorophyll a concentrations. Other sources of iron such as run-off and glacial melt are not represented explicitly in the model, however we discuss their role in the local iron budget.

show abstract

Section: The South Georgia Island Mass Effectsupporting

confidence: 51%

Section: The South Georgia Island Mass Effectmentioning

confidence: 88%

Section: The South Georgia Island Mass Effectmentioning

confidence: 99%

See 1 more Smart Citation

Sedimentary and atmospheric sources of iron around South Georgia, Southern Ocean: a modelling perspective

et al. 2014

View full text Add to dashboard Cite

show abstract

“…These waters are predominantly HNLC with a phytoplankton community dominated by nano-and picoflagellates but characteristically contain even less Chl a than the SAZ (Becquevort et al, 2000;Moore and Abbott, 2000;Kopczyńska et al, 2001;Olguín and Alder, 2011). The exception to this is where iron concentrations in surface waters are enhanced by upwelling and/or sediment input/resuspension from sea floor bathymetry and sub-Antarctic islands (Figure 2) (e.g., Pollard et al, 2002;Ardelan et al, 2010;Rembauville et al, 2015b). This pattern differs from that of macronutrients, which decline northwards across the POOZ region, nitrate falling from ∼25-20 µmol l −1 and silicate from ∼60-10 µmol l −1 .…”

Section: Permanently Open Ocean Zonementioning

confidence: 99%

Southern Ocean Phytoplankton in a Changing Climate

2017

View full text Add to dashboard Cite

Phytoplankton are the base of the Antarctic food web, sustain the wealth and diversity of life for which Antarctica is renowned, and play a critical role in biogeochemical cycles that mediate global climate. Over the vast expanse of the Southern Ocean (SO), the climate is variously predicted to experience increased warming, strengthening wind, acidification, shallowing mixed layer depths, increased light (and UV), changes in upwelling and nutrient replenishment, declining sea ice, reduced salinity, and the southward migration of ocean fronts. These changes are expected to alter the structure and function of phytoplankton communities in the SO. The diverse environments contained within the vast expanse of the SO will be impacted differently by climate change; causing the identity and the magnitude of environmental factors driving biotic change to vary within and among bioregions. Predicting the net effect of multiple climate-induced stressors over a range of environments is complex. Yet understanding the response of SO phytoplankton to climate change is vital if we are to predict the future state/s of the ecosystem, estimate the impacts on fisheries and endangered species, and accurately predict the effects of physical and biotic change in the SO on global climate. This review looks at the major environmental factors that define the structure and function of phytoplankton communities in the SO, examines the forecast changes in the SO environment, predicts the likely effect of these changes on phytoplankton, and considers the ramifications for trophodynamics and feedbacks to global climate change. Predictions strongly suggest that all regions of the SO will experience changes in phytoplankton productivity and community composition with climate change. The nature, and even the sign, of these changes varies within and among regions and will depend upon the magnitude and sequence in which these environmental changes are imposed. It is likely that predicted changes to phytoplankton communities will affect SO biogeochemistry, carbon export, and nutrition for higher trophic levels.

show abstract

“…Boundary currents, such as the Antarctic Slope Current (ASC) and the Antarctic Coastal Current (CC), described below, transport Antarctic krill from spawning areas near the coast to the Scotia Sea (Hofmann et al 1998;Murphy et al 2004;Thorpe et al 2004Thorpe et al , 2007. Furthermore, shelf waters around the Antarctic Peninsula and the South Shetland Islands exhibit elevated concentrations of iron (Fitzwater et al 2000;Ardelan et al 2010;Frants et al 2012a,b) that promote biological productivity in regions that are replete in macronutrients but limited in micronutrients (Martin et al 1990;Fitzwater et al 2000). Advection of iron from the continental shelves of the Weddell Sea to the Scotia Sea is a key reason for the enhancement of surface chlorophyll in eastern Drake Passage (Korb et al 2004;Zhou et al 2010;Thompson and Youngs 2013;Wadley et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Weddell Sea Export Pathways from Surface Drifters

Youngs

Thompson

Flexas

et al. 2015

Journal of Physical Oceanography

View full text Add to dashboard Cite

The complex export pathways that connect the surface waters of the Weddell Sea with the Antarctic Circumpolar Current influence water mass modification, nutrient fluxes, and ecosystem dynamics. To study this exchange, 40 surface drifters, equipped with temperature sensors, were released into the northwestern Weddell Sea's continental shelf and slope frontal system in late January 2012. Comparison of the drifter trajectories with a similar deployment in early February 2007 provides insight into the interannual variability of the surface circulation in this region. Observed differences in the 2007 and 2012 drifter trajectories are related to a variable surface circulation responding to changes in wind stress curl over the Weddell Gyre. Differences between northwestern Weddell Sea properties in 2007 and 2012 include 1) an enhanced cyclonic wind stress forcing over the Weddell Gyre in 2012; 2) an acceleration of the Antarctic Slope Current (ASC) and an offshore shift of the primary drifter export pathway in 2012; and 3) a strengthening of the Coastal Current (CC) over the continental shelf in 2007. The relationship between wind stress forcing and surface circulation is reproduced over a longer time period in virtual drifter deployments advected by a remotely sensed surface velocity product. The mean offshore position and speed of the drifter trajectories are correlated with the wind stress curl over the Weddell Gyre, although with different temporal lags. The drifter observations are consistent with recent modeling studies suggesting that Weddell Sea boundary current variability can significantly impact the rate and source of exported surface waters to the Scotia Sea, a process that determines regional chlorophyll distributions.

show abstract

Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean

Cited by 115 publications

References 58 publications

Sedimentary and atmospheric sources of iron around South Georgia, Southern Ocean: a modelling perspective

Sedimentary and atmospheric sources of iron around South Georgia, Southern Ocean: a modelling perspective

Southern Ocean Phytoplankton in a Changing Climate

Weddell Sea Export Pathways from Surface Drifters

Contact Info

Product

Resources

About