Eddies enhance biological production in the Weddell‐Scotia Confluence of the Southern Ocean

Kahru, Mati; Mitchell, B. Greg; Gille, Sarah T.; Hewes, Christopher D.; Holm‐Hansen, Osmund

doi:10.1029/2007gl030430

Cited by 127 publications

(99 citation statements)

References 25 publications

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“…Physical processes that may contribute to the supply of new iron include upwelling (de Baar et al, 1995), vertical diffusive flux , horizontal advection (Ellwood et al, 2008;Sedwick et al, 2008;Bowie et al, 2009), the interaction between bathymetry and currents (Blain et al, 2007;Sokolov et al, 2007), and mesoscale eddies and cross-frontal mixing (Kahru et al, 2007). In addition, the melting of sea ice and icebergs also can supply or redistribute iron in surface waters (Smith et al, 2007;Lannuzel et al, 2008;Lancelot et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

Misumi

Lindsay

Moore³

et al. 2014

Biogeosciences

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Abstract. We investigated the simulated iron budget in ocean surface waters in the 1990s and 2090s using the Community Earth System Model version 1 and the Representative Concentration Pathway 8.5 future CO 2 emission scenario. We assumed that exogenous iron inputs did not change during the whole simulation period; thus, iron budget changes were attributed solely to changes in ocean circulation and mixing in response to projected global warming, and the resulting impacts on marine biogeochemistry. The model simulated the major features of ocean circulation and dissolved iron distribution for the present climate. Detailed iron budget analysis revealed that roughly 70 % of the iron supplied to surface waters in high-nutrient, low-chlorophyll (HNLC) regions is contributed by ocean circulation and mixing processes, but the dominant supply mechanism differed by region: upwelling in the eastern equatorial Pacific and vertical mixing in the Southern Ocean. For the 2090s, our model projected an increased iron supply to HNLC waters, even though enhanced stratification was predicted to reduce iron entrainment from deeper waters. This unexpected result is attributed largely to changes in gyre-scale circulations that intensified the advective supply of iron to HNLC waters. The simulated primary and export production in the 2090s decreased globally by 6 and 13 %, respectively, whereas in the HNLC regions, they increased by 11 and 6 %, respectively.Roughly half of the elevated production could be attributed to the intensified iron supply. The projected ocean circulation and mixing changes are consistent with recent observations of responses to the warming climate and with other Coupled Model Intercomparison Project model projections. We conclude that future ocean circulation has the potential to increase iron supply to HNLC waters and will potentially buffer future reductions in ocean productivity.

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Section: Introductionmentioning

confidence: 99%

The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

Misumi

Lindsay

Moore³

et al. 2014

Biogeosciences

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“…Using satellite and Argo data, Carranza and Gille (2015) reported a correlation of increased Chl a in the SO with increased mixed layer depth. A positive SAM also increases eddy formation and transports SAZ water across the Polar Front (Meredith and Hogg, 2006;Kahru et al, 2007;Hogg et al, 2008). These cyclonic eddies trap warm water at their core, enhance stratification, and upwell nutrients and iron, creating ideal conditions for phytoplankton productivity (Kahru et al, 2007) and may also contribute significantly to ocean warming in the POOZ (Hogg et al, 2008).…”

Section: Permanently Open Ocean Zonementioning

confidence: 99%

Southern Ocean Phytoplankton in a Changing Climate

2017

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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.

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“…Temporal and spatial scales of atmospheric and oceanographic process should be considered when weighing their predictive capabilities on the formation and persistence of biological hotspots (Palacios et al 2006). For example, eddies are important sources of biological production that may contain high concentrations of chl a and krill (Kahru et al 2007, Santora et al 2012a, and likely affect spatial and temporal variation in top predator hotspots (Gende & Sigler 2006, Block et al 2011. Bathymetry derived circulation patterns and coastal transport processes (e.g.…”

Section: Drivers Of Hotspotsmentioning

confidence: 99%

Spatio-temporal persistence of top predator hotspots near the Antarctic Peninsula

Santora¹,

Veit²

2013

Mar. Ecol. Prog. Ser.

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We quantified species richness and abundance of seabirds and marine mammals in order to identify marine areas that are persistently attractive to top predators. Shipboard surveys across a 150 000 km 2 grid off the Antarctic Peninsula were conducted once or twice each year from 2003 to 2011 during which the distribution and abundance of top predators were mapped. We hypothesized that spatial organization of species richness and abundance hotspots reflect persistent habitat use and are regionalized according to distance from land and oceanographic boundaries. To test this, we used a new hotspot variance metric based on the percentage of time that the species richness or abundance estimate at any one location is greater than 1 standard deviation above the long term means for the entire survey grid. Species richness hotspots were based on all species sighted, while abundance hotspots were based on concentrations of 16 species: 13 seabirds (penguins, petrels and albatrosses), 1 pinniped and 2 baleen whales. Species abundance hotspots reflected 2 major groupings -those with oceanic and coastal origins. We identified 15 richness hotspots, 9 of which were in proximity to the southern Antarctic Circumpolar Current front; the 6 others were associated with major breeding colonies and the location of 2 submarine canyon systems. Our approach integrates temporal and spatial variances over 14 individual surveys and provides useful reference points for identifying ecologically important areas, refining food web models and developing spatial management of and conservation strategies for marine ecosystems.

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Eddies enhance biological production in the Weddell‐Scotia Confluence of the Southern Ocean

Cited by 127 publications

References 25 publications

The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

Southern Ocean Phytoplankton in a Changing Climate

Spatio-temporal persistence of top predator hotspots near the Antarctic Peninsula

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