Summer microplankton community structure across the Scotia Sea: implications for biological carbon  export

Korb, Rebecca E.; Whitehouse, Martin J.; Gordon, Marina; Ward, Peter; Poulton, Alex J

doi:10.5194/bgd-6-9781-2009

Cited by 3 publications

(6 citation statements)

References 45 publications

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“…We put forward the hypothesis that ikaite precipitation had occurred in the sea ice brines of the Weddell–Scotia Confluence during the preceding winter and the resultant DIC‐ and TA‐poor brines were released into the underlying water as the ice melted, transferring the inorganic carbon characteristics into the summer mixed layer. The absence of calcifying phytoplankton in this region (Korb et al, 2010) supports the proposed mechanism of the observed depletion in DIC and TA at the sea surface.…”

Section: Discussionsupporting

confidence: 73%

“…Chlorophyll‐a concentrations sharply decreased to a minimum of 0.21 mg m −3 beneath the sea ice at station 1. For the MIZ (stations 1–6), the phytoplankton community was dominated by naked, heterotrophic dinoflagellates with diatoms accounting for between 21 and 46% of the total cell abundance (Korb et al, 2010). North of the South Orkney Islands to 59°S (stations 8–13) the community consisted of a mixture of dinoflagellates and cryptophytes, with less than 20% diatoms (Korb et al, 2010).…”

Section: Resultsmentioning

confidence: 99%

“…The gradient of the phosphate regression line (48) is much smaller than that predicted by either nutrient utilization ratio. The decreasing concentration of silicate indicates the activity of the diatoms observed in this region (Korb et al, 2010). Despite the bloom being dominated by naked dinoflagellates, with little photosynthetic ability, it is predicted that the few diatoms present would account for the majority of the photosynthetic activity and carbon utilization.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Jones¹,

Bakker²,

Venables³

et al. 2010

Tellus B: Chemical and Physical Meteorology

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A B S T R A C TThe effect of sea ice melt on the carbonate chemistry of surface waters in the Weddell-Scotia Confluence, Southern Ocean, was investigated during January 2008. Contrasting concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA) and the fugacity of carbon dioxide (f CO 2 ) were observed in and around the receding sea ice edge. The precipitation of carbonate minerals such as ikaite (CaCO 3 ·6H 2 O) in sea ice brine has the net effect of decreasing DIC and TA and increasing the f CO 2 in the brine. Deficits in DIC up to 12 ± 3 μmol kg −1 in the marginal ice zone (MIZ) were consistent with the release of DIC-poor brines to surface waters during sea ice melt. Biological utilization of carbon was the dominant processes and accounted for 41 ± 1 μmol kg −1 of the summer DIC deficit. The data suggest that the combined effects of biological carbon uptake and the precipitation of carbonates created substantial undersaturation in f CO 2 of 95 μatm in the MIZ during summer sea ice melt. Further work is required to improve the understanding of ikaite chemistry in Antarctic sea ice and its importance for the sea ice carbon pump.

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Section: Discussionsupporting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Jones¹,

Bakker²,

Venables³

et al. 2010

Tellus B: Chemical and Physical Meteorology

View full text Add to dashboard Cite

show abstract

“…In the AAZ west of South Georgia, diatoms also dominate phytoplankton biomass in late summer with a strong contribution of Pseudo‐nitzschia , T. antarctica , and E. antarctica var. antarctica (Korb and Whitehouse ; Korb et al ). We observed a strong contribution of the very large diatom Thalassiothrix antarctica together with Corethron spp.…”

Section: Discussionmentioning

confidence: 99%

Particulate matter stoichiometry driven by microplankton community structure in summer in the Indian sector of the Southern Ocean

Rembauville

Blain

Caparros

et al. 2016

Limnology & Oceanography

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Microplankton community structure and particulate matter stoichiometry were investigated in a late summer survey across the Subantarctic and Polar Front in the Indian sector of the Southern Ocean. Microplankton community structure exerted a first order control on PON:POP stoichiometry with diatom‐dominated samples exhibiting much lower ratios (4–6) than dinoflagellate and ciliate‐dominated samples (10–21). A significant fraction of the total chlorophyll a (30–70%) was located beneath the euphotic zone and mixed layer and sub‐surface chlorophyll features were associated to transition layers. Although microplankton community structure and biomass was similar between mixed and transition layers, the latter was characterized by elevated Chl:POC ratios indicating photoacclimation of mixed layer communities. Empty diatom frustules, in particular of Fragilariopsis kerguelensis and Pseudo‐nitzschia, were found to accumulate in the Antarctic Zone transition layer and were associated to elevated BSi:POC ratios. Furthermore, high Si(OH)4 diffusive fluxes (>1 mmol m2 d−1) into the transition layer appeared likely to sustain silicification. We suggest transition layers as key areas of C and Si decoupling through (1) physiological constraints on carbon and silicon fixation (2) as active foraging sites for grazers that preferentially remineralize carbon. On the Kerguelen Plateau, the dominant contribution of Chaetoceros Hyalochaete resting spores to microplankton biomass resulted in a three‐fold enhancement of POC concentration at 250 m, compared to other stations. These findings further highlight the importance of diatom resting spores as a significant vector of carbon export through the intense remineralization horizons characteristing Southern Ocean ecosystems.

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“…As phytoplankton stocks (Boyce et al, 2010) and diatom production (Bopp et al, 2005) decline globally under climate change, carbon export to deeper layers via diatom blooms will be affected (Korb et al, 2010). Additionally, in the Southern Ocean, intense grazing on diatoms by krill efficiently transfers biomass to higher trophic levels (Smetacek et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Metatranscriptomes reveal functional variation in diatom communities from the Antarctic Peninsula

et al. 2015

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Functional genomics of diatom-dominated communities from the Antarctic Peninsula was studied using comparative metatranscriptomics. Samples obtained from diatom-rich communities in the Bransfield Strait, the western Weddell Sea and sea ice in the Bellingshausen Sea/Wilkins Ice Shelf yielded more than 500K pyrosequencing reads that were combined to produce a global metatranscriptome assembly. Multi-gene phylogenies recovered three distinct communities, and diatom-assigned contigs further indicated little read-sharing between communities, validating an assembly-based annotation and analysis approach. Although functional analysis recovered a core of abundant shared annotations that were expressed across the three diatom communities, over 40% of annotations (but accounting for o10% of sequences) were community-specific. The two pelagic communities differed in their expression of N-metabolism and acquisition genes, which was almost absent in post-bloom conditions in the Weddell Sea community, while enrichment of transporters for ammonia and urea in Bransfield Strait diatoms suggests a physiological stance towards acquisition of reduced N-sources. The depletion of carbohydrate and energy metabolism pathways in sea ice relative to pelagic communities, together with increased light energy dissipation (via LHCSR proteins), photorespiration, and NO 3 − uptake and utilization all pointed to irradiance stress and/or inorganic carbon limitation within sea ice. Ice-binding proteins and cold-shock transcription factors were also enriched in sea ice diatoms. Surprisingly, the abundance of gene transcripts for the translational machinery tracked decreasing environmental temperature across only a 4°C range, possibly reflecting constraints on translational efficiency and protein production in cold environments.

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Summer microplankton community structure across the Scotia Sea: implications for biological carbon export

Cited by 3 publications

References 45 publications

Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Particulate matter stoichiometry driven by microplankton community structure in summer in the Indian sector of the Southern Ocean

Metatranscriptomes reveal functional variation in diatom communities from the Antarctic Peninsula

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