Water-column processes in the West Antarctic Peninsula and the Ross Sea: Interannual variations and foodweb structure

Ducklow, Hugh W.; Fraser, William R.; Karl, David M.; Quetin, Langdon B.; Ross, Robin M.; Smith, Raymond C.; Stammerjohn, Sharon; Vernet, María; Daniels, Robert M.

doi:10.1016/j.dsr2.2006.02.009

Cited by 84 publications

(93 citation statements)

References 42 publications

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“…1). The oceanographic setting and microbial ecology of this region are described in Ducklow et al (2006). Abundance of all prokaryotes was measured using flow cytometry with SYBR green staining (Applied Biosystems).…”

Section: Methodsmentioning

confidence: 99%

“…The low rates of bacterial production in polar regions could be due to bacteria being inactive in these perennially cold waters (Ducklow et al 2001;Smith and del Giorgio 2003). Early work suggested that bacterial growth is limited in cold temperatures, potentially requiring higher concentrations of substrate to achieve rates similar to bacterial growth in warmer, temperate waters (Pomeroy and Wiebe 2001).…”

mentioning

confidence: 99%

“…One major difference between the two is that the Arctic Ocean receives terrestrial inputs of organic material, while the Southern Ocean and coastal waters of Antarctica do not. However, primary production is still the largest source of labile organic material to both polar oceans (Ducklow et al 2006). Rates of primary production are often quite high in both polar systems, but bulk bacterial production ( 3 H-leucine incorporation rates) in the Ross Sea (Antarctica) and in various Arctic waters is low compared to rates in temperate regions (Ducklow et al 2001;Kirchman et al 2009b).…”

mentioning

confidence: 99%

“…However, primary production is still the largest source of labile organic material to both polar oceans (Ducklow et al 2006). Rates of primary production are often quite high in both polar systems, but bulk bacterial production ( 3 H-leucine incorporation rates) in the Ross Sea (Antarctica) and in various Arctic waters is low compared to rates in temperate regions (Ducklow et al 2001;Kirchman et al 2009b). Consequently, the ratio of bacterial production to primary production is lower in both the Arctic Ocean and Ross Sea than in temperate oceans (Kirchman et al 2009b).…”

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confidence: 99%

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Abundance and single‐cell activity of bacterial groups in Antarctic coastal waters

Straza

Ducklow

Murray

et al. 2010

Limnology & Oceanography

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We estimated the abundance and single-cell activity of bacterial groups in waters off the West Antarctic Peninsula (WAP) using a combination of microautoradiography and fluorescent in situ hybridization (FISH). The abundance of the Ant4D3 subgroup, detected by a new FISH probe, was 10% of the total community and half of the gammaproteobacterial population. The Ant4D3, Polaribacter, and SAR11 subgroups accounted for the majority of the Gammaproteobacteria, Sphingobacteria-Flavobacteria, and Alphaproteobacteria, respectively. Approximately 40% of the total microbial community actively incorporated leucine (added at 20 nmol L 21 ), while a smaller fraction (12-22%) used protein and an amino acid mixture (added at tracer concentrations). The fractions of SAR11, Polaribacter, and Ant4D3 that were active differed from each other and varied among substrates. SAR11 had the largest fraction of active cells incorporating leucine, while Polaribacter dominated the community using protein. The fraction of Ant4D3 using different compounds did not vary, but this group dominated the incorporation of amino acids, and was an abundant and active component of the bacterial community. Bacteria in the WAP region were as active as bacteria in the Mid-Atlantic Bight, even though total bacterial production was lower in the WAP. Though persistently cold (0-1uC) and dominated by different bacterial taxa, the single-cell activity of this summertime Antarctic bacterial community was comparable to that of temperate communities.

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Section: Methodsmentioning

confidence: 99%

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Abundance and single‐cell activity of bacterial groups in Antarctic coastal waters

Straza

Ducklow

Murray

et al. 2010

Limnology & Oceanography

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“…While such productivity hotspots comprise only a fraction of the Southern Ocean, they are important biogeochemically in terms of total carbon flows and for commercially important food webs (Atkinson et al 2001, Schlitzer 2002, Ducklow et al 2006). South Georgia is also particularly well suited to such a study.…”

Section: Introductionmentioning

confidence: 99%

Role of krill versus bottom-up factors in controlling phytoplankton biomass in the northern Antarctic waters of South Georgia

Whitehouse

Atkinson²,

Ward³

et al. 2009

Mar. Ecol. Prog. Ser.

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The extent to which Antarctic phytoplankton stocks are controlled by 'bottom-up' and/or 'top-down' factors is highly variable. Here we consider data collected at South Georgia during 3 summer surveys that recorded substantial hydrographic variability. A suite of bottom-up and top-down controlling factors were measured simultaneously at the mesoscale. Sea surface temperature varied by > 2°C, macronutrients ranged from near-winter concentrations to near-depleted, while mean densities of a major grazer, krill Euphausia superba, varied between near-zero and > 400 g wet mass m -2 . A general linear model was used to identify the main factors implicated in the observed differences in phytoplankton biomass. Despite east-to-west and on-to off-shelf temperature gradients, temperature per se was not implicated in phytoplankton variability. Also, while there was an abundance of NO 3 -N in surface waters, NH 4 -N was the key nutrient throughout. A domed relationship between phytoplankton and krill peaked between 2 and 4 mg chlorophyll a m -3 and 6 and 30 g krill m -2 . The positive side of this dome was represented by the west off-shelf region downstream of South Georgia. Here, an ample supply of micro-and macronutrients promoted high primary production, and low densities of krill presumably had little grazing effect. This positive relationship between krill and phytoplankton biomasses was interpreted as krill accumulating in areas of good feeding conditions. The negative side of the dome was typified by the east off-shelf region, where macronutrients remained high, primary production rates were low, and krill densities were very high. The grazing rates calculated here suggested that krill affect their food stocks severely, and the negative krill-phytoplankton relationship in this region may reflect locally high krill densities driving down their food supply.

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Interannual variability in net community production at the Western Antarctic Peninsula region (1997–2014)

Cassar

Huang

et al. 2016

JGR Oceans

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In this study, we examined the interannual variability of net community production (NCP) in the Western Antarctic Peninsula (WAP) using in situ O2/Ar‐NCP estimates (2008–2014) and satellite data (SeaWiFS and MODIS‐Aqua) from 1997 to 2014. We found that NCP generally first peaks offshore and follows sea‐ice retreat from offshore to inshore. Annually integrated NCP (ANCP) displays an onshore‐to‐offshore gradient, with coastal and shelf regions up to 8 times more productive than offshore regions. We examined potential drivers of interannual variability in the ANCP using an Empirical Orthogonal Function (EOF) analysis. The EOF's first mode explains ∼50% of the variance, with high interannual variability observed seaward of the shelf break. The first principal component is significantly correlated with the day of sea‐ice retreat (R = −0.58, p < 0.05), as well as the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO) climate indices in austral spring. Although the most obvious pathway by which the day of sea‐ice retreat influences NCP is by controlling light availability early in the growing season, we found that the effect of day of sea‐ice retreat on NCP persists throughout the growing season, suggesting that additional controls, such as iron availability, are preconditioned or correlated to the day of sea‐ice retreat.

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Water-column processes in the West Antarctic Peninsula and the Ross Sea: Interannual variations and foodweb structure

Cited by 84 publications

References 42 publications

Abundance and single‐cell activity of bacterial groups in Antarctic coastal waters

Abundance and single‐cell activity of bacterial groups in Antarctic coastal waters

Role of krill versus bottom-up factors in controlling phytoplankton biomass in the northern Antarctic waters of South Georgia

Interannual variability in net community production at the Western Antarctic Peninsula region (1997–2014)

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