The Simulated Biological Response to Southern Ocean Eddies via Biological Rate Modification and Physical Transport

Tyler Rohr; Cheryl Harrison; Matthew C. Long; Peter Gaube; Scott C. Doney

doi:10.1029/2019gb006385

Supplementary material to "Imprint of Southern Ocean eddies on chlorophyll"

10.5194/bg-2018-70-supplement ◽

2018 ◽

Author(s):

Ivy Frenger ◽

Matthias Münnich ◽

Nicolas Gruber

Keyword(s):

Southern Ocean ◽

Ocean Eddies ◽

Supplementary Material

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Biological response to physical processes in the Indian Ocean sector of the Southern Ocean: a case study in the coastal and oceanic waters

Environmental Monitoring and Assessment ◽

10.1007/s10661-014-3990-4 ◽

2014 ◽

Vol 186 (12) ◽

pp. 8109-8124

Author(s):

N. Anilkumar ◽

Racheal Chacko ◽

P. Sabu ◽

Honey U. K. Pillai ◽

Jenson V. George ◽

...

Keyword(s):

Indian Ocean ◽

Southern Ocean ◽

Biological Response ◽

Physical Processes ◽

Indian Ocean Sector ◽

The Indian Ocean ◽

Ocean Sector

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The subsurface biological structure of Southern Ocean eddies revealed by BGC-Argo floats

Journal of Marine Systems ◽

10.1016/j.jmarsys.2021.103569 ◽

2021 ◽

pp. 103569

Author(s):

Jiaoyang Su ◽

Peter Strutton ◽

Christina Schallenberg

Keyword(s):

Southern Ocean ◽

Biological Structure ◽

Ocean Eddies ◽

Argo Floats

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Impact of desert and volcanic aerosol deposition on phytoplankton in the South Indian Ocean and Southern Ocean

10.5194/egusphere-egu2020-20767 ◽

2020 ◽

Author(s):

Carla Geisen ◽

Celine Ridame ◽

Emilie Journet ◽

Benoit Caron ◽

Dominique Marie ◽

...

Keyword(s):

Indian Ocean ◽

Southern Ocean ◽

Primary Production ◽

Algal Growth ◽

Biological Response ◽

South Indian Ocean ◽

Desert Dust ◽

South Indian ◽

Natural Aerosols ◽

Fe Addition

The Southern Ocean is known to be the largest High Nutrient Low Chlorophyll (HNLC) area of the global ocean, where algal development is mainly limited by iron (Fe) deficiency, except in few naturally Fefertilized areas (e.g. around Kerguelen plateau). The availability of different nutrients is unevenly distributed in this area. Thus, northwards the polar front, nitrogen and phosphorus (N and P) concentrations are high, but the scarcity of silicon (Si) limits the growth of diatoms (HN-LSi-LC). Further North, the Southern Indian Ocean is characterized by macronutrient limitation and low primary production (LNLC).In these areas, atmospheric input could play a major role in the nutrient supply of primary producers. The main aim of this study is to assess the biological response of local phytoplankton communities to a deposition of two types of natural aerosols: desert dust and volcanic ash. Preliminary trace-metal clean laboratory experiments enabled us to quantify the abiotic dissolution of main macro- and micronutrients in dry and wet deposition mode of different natural aerosols of these types that yield us to choose Patagonia dust and ash from the Icelandic volcano Eyjafjallaj&#246;kull for our experiment at sea. We set up a series of on-board trace-metal clean microcosm experiments in the contrasted biogeochemical conditions of the South Indian Ocean and Southern Ocean with addition of realistic amounts of dust and ash of respectively 2 and 25 mg.L-1. Experiments ran over 48 hours to evaluate the triggered primary production and cell abundances. Primary production was estimated by 13C spike and biogenic Si (bSi) uptake rates were assessed by 30Si spike. Parallel experiments with nutrient addition (dFe, DIP, DIN and dSi) along with flux cytometry for estimation of pico- and nanophytoplankton cells enabled us to determine which element(s) dissolved from the aerosols was responsible for the enhanced algal growth. The highest CO2 fixation rate of 50 mg.m-3.day-1 was found at the natural Fe fertilized Kerguelen plateau station. Dust, ash and Fe addition triggered primary production, and CO2 fixation doubled in these treatments. We recorded an enrichment of b30Si, indicating an increase of Si uptake rate, mostly stimulated by Fe addition. At the different HNLC stations (high N - low Si and high N - high Si), Fe and aerosol addition induced as well increased CO2 fixation. In the northern LNLC stations, algal growth was stimulated by nitrogen addition as expected, but Fe, Si and aerosol addition also triggered a biological response from Synechococcus cyanobacteria and pico- and nanoeukaryotes. Noteworthy, in most experiments the two contrasted aerosol types (desert dust and volcanic ash) at particle charges which varied over more than an order of magnitude triggered very similar biological responses in all of the sampled areas, even with distinct elementary and mineral compositions (e.g. the Icelandic volcano ash is 64 % amorphous and contains roughly twice the amount of Fe, P, Mn and Zn compared to the Patagonian desert dust which is only 48 % amorphous).

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Does the sensitivity of Southern Ocean circulation depend upon bathymetric details?

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2013.0050 ◽

2014 ◽

Vol 372 (2019) ◽

pp. 20130050 ◽

Cited By ~ 11

Author(s):

Andrew McC. Hogg ◽

David R. Munday

Keyword(s):

Southern Ocean ◽

Wind Stress ◽

Ocean Circulation ◽

Bottom Water ◽

Deep Ocean ◽

Ocean Eddies ◽

Oceanic Response ◽

Water Formation ◽

Circumpolar Current ◽

Bottom Water Formation

The response of the major ocean currents to changes in wind stress forcing is investigated with a series of idealized, but eddy-permitting, model simulations. Previously, ostensibly similar models have shown considerable variation in the oceanic response to changing wind stress forcing. Here, it is shown that a major reason for these differences in model sensitivity is subtle modification of the idealized bathymetry. The key bathymetric parameter is the extent to which the strong eddy field generated in the circumpolar current can interact with the bottom water formation process. The addition of an embayment, which insulates bottom water formation from meridional eddy fluxes, acts to stabilize the deep ocean density and enhances the sensitivity of the circumpolar current. The degree of interaction between Southern Ocean eddies and Antarctic shelf processes may thereby control the sensitivity of the Southern Ocean to change.

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