Seasonal dynamics in diatom and particulate export fluxes to the deep sea in the Australian sector of the southern Antarctic Zone

Rigual-Hernández, Andrés S.; Trull, Thomas W.; Bray, Stephen G.; Closset, Ivia; Armand, Leanne K.

doi:10.1016/j.jmarsys.2014.10.002

Cited by 43 publications

(58 citation statements)

References 97 publications

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“…transport by mesoscale eddies) of a coccolithophore bloom produced in more northerly latitudes. Lastly, the composition of the biogeochemical fluxes and diatom assemblages collected by the traps are characteristic of AZ waters (Rigual- Hernández et al, 2015a), further supporting the idea that the coccolithophores captured by the traps were produced close to the site. All this clearly indicates that in 2001 E. huxleyi was an established member of the phytoplankton communities of the Antarctic zone to the C-calcite south of Australia.…”

Section: Origin Magnitude and Composition Of The Coccolithophoresmentioning

confidence: 57%

“…The fluxes of all biogeochemical components were closely correlated ( Table 2 in Rigual- Hernández et al, 2015a). Coc- It is important to note that satellite PIC concentration estimates have been reported to be biased for high-latitude systems of the Southern Ocean where the satellite algorithm is thought to produce overestimates (Balch et al, 2016;Trull et al, 2018).…”

Section: Seasonal Dynamics Of Coccolith Export Fluxesmentioning

confidence: 86%

“…Silicate exhibits the strongest summer drawdown of all the macronutrients, reaching ∼ 30 % of its winter values ( Fig. 2; Trull et al, 2001b) mainly due to diatom growth and subsequent biogenic silica export to the deep sea (Rigual-Hernández et al, 2015a). The low algal biomass accumulation in the region is attributed to the very low iron levels (0.1-0.2 nM; Boyd et al, 2000a;Sohrin et al, 2000).…”

Section: Regional Setting and Oceanographymentioning

confidence: 97%

“…The 61 • S site is characterised by weak currents with a mean eastward geostrophic surface velocity of approximately 0.03 ± 0.02 m s −1 (Trull et al, 2001b). The site is north of the seasonal sea ice zone (Massom et al, 2013;Rigual-Hernández et al, 2015a) and remote from any known iceberg pathway (Gladstone et al, 2001).…”

Section: Sediment Trap Experimentsmentioning

confidence: 99%

“…A description of the analytical procedures for the estimation of geochemical fluxes is provided in Trull et al (2001a) and Rigual-Hernández et al (2015a). One aliquot was used for siliceous and calcareous microplankton and nanoplankton analyses.…”

Section: Sample Processing and Coccolithophore Counting Proceduresmentioning

confidence: 99%

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Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

et al. 2018

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Abstract. The Southern Ocean is experiencing rapid and relentless change in its physical and biogeochemical properties. The rate of warming of the Antarctic Circumpolar Current exceeds that of the global ocean, and the enhanced uptake of carbon dioxide is causing basin-wide ocean acidification. Observational data suggest that these changes are influencing the distribution and composition of pelagic plankton communities. Long-term and annual field observations on key environmental variables and organisms are a critical basis for predicting changes in Southern Ocean ecosystems. These observations are particularly needed, since highlatitude systems have been projected to experience the most severe impacts of ocean acidification and invasions of allochthonous species.

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Section: Origin Magnitude and Composition Of The Coccolithophoresmentioning

confidence: 57%

Section: Seasonal Dynamics Of Coccolith Export Fluxesmentioning

confidence: 86%

Section: Regional Setting and Oceanographymentioning

confidence: 97%

Section: Sediment Trap Experimentsmentioning

confidence: 99%

Section: Sample Processing and Coccolithophore Counting Proceduresmentioning

confidence: 99%

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Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

et al. 2018

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Seasonal variations, origin, and fate of settling diatoms in the Southern Ocean tracked by silicon isotope records in deep sediment traps

Closset

Cardinal

Bray

et al. 2015

Global Biogeochemical Cycles

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The Southern Ocean plays a pivotal role in the control of atmospheric CO 2 levels, via both physical and biological sequestration processes. The biological carbon transfer to the ocean interior is tightly coupled to the availability of other elements, especially iron as a trace-limiting nutrient and dissolved silicon as the mineral substrate that allows diatoms to dominate primary production. Importantly, variations in the silicon cycling are large but not well understood. Here we use δ 30 Si measurements to track seasonal flows of silica to the deep sea, as captured by sediment trap time series, for the three major zones (Antarctic, AZ; Polar Frontal, PFZ; and Sub-Antarctic, SAZ) of the open Southern Ocean. Variations in the exported flux of biogenic silica (BSi) and its δ 30 Si composition reveal a range of insights, including that (i) the sinking rate of BSi exceeds 200 m d À1 in summer in the AZ yet decreases to very low values in winter that allow particles to remain in the water column through to the following spring, (ii) occasional vertical mixing events affect the δ 30 Si composition of exported BSi in both the SAZ and AZ, and (iii) the δ 30 Si signature of diatoms is well conserved through the water column despite strong BSi and particulate organic carbon (POC) attenuation at depth and is closely linked to the Si consumption in surface waters. With the strong coupling observed between BSi and POC fluxes in PFZ and AZ, these data provide new constraints for application to biogeochemical models of seasonal controls on production and export.

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Synchronized autonomous sampling reveals coupled pulses of biomass and export of morphologically different diatoms in the Southern Ocean

Blain

Rembauville

Crispi

et al. 2020

Limnology & Oceanography

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The Southern Ocean hosts a large diversity of diatoms that play a major role in carbon fluxes. How the seasonal dynamics in the abundance of specific taxa in surface waters are linked to their contribution to carbon export remains, however, poorly understood. We present here synchronized observations from autonomous samplers deployed in the mixed layer (42 m) and at depth (300 m) during an entire productive season (October 2016 to March 2017) in the iron fertilized region of the central plateau of Kerguelen. Microscopic observations of surface water collected every 11 d revealed 30 different diatom taxa, each contributing to > 1% of total carbon biomass throughout the season. The synchronized sampling revealed a common pattern for diatom taxa belonging to 12 different genera, consisting, for a given taxon, in short pulses of abundance in surface waters followed by export. We explain these coupled dynamics by the formation of aggregates that are produced when a critical diatom cell abundance is reached. This control of the maximum abundance of a given diatom drives the seasonal change in the slope of the size‐class distribution of the diatom community. It further constrains the total carbon diatom biomass in a narrow range of values due to the inverse relationship between total diatom abundance and their community‐weighted mean biomass. This coupling let us conclude that aggregate formation, and the export to depth, occurs throughout the season for diatoms with different morphologies.

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Seasonal dynamics in diatom and particulate export fluxes to the deep sea in the Australian sector of the southern Antarctic Zone

Abstract: 17Particle fluxes were recorded over a one-year period in the southern Antarctic

Cited by 43 publications

References 97 publications

Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

Seasonal variations, origin, and fate of settling diatoms in the Southern Ocean tracked by silicon isotope records in deep sediment traps

Synchronized autonomous sampling reveals coupled pulses of biomass and export of morphologically different diatoms in the Southern Ocean

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