News

Global oceanic oxygenation controlled by the Southern Ocean through the last deglaciation

Abstract.

"Ocean dissolved oxygen (DO) can provide insights on how the marine carbon cycle affects global climate change. However, the net global DO change and the controlling mechanisms remain uncertain through the last deglaciation. Here, we present a globally integrated DO reconstruction using thallium isotopes, corroborating lower global DO during the Last Glacial Maximum [19 to 23 thousand years before the present (ka B.P.)] relative to the Holocene. [...]".

 

Source: Science Advances  
Authors: Yi Wang et al.
DOI: 10.1126/sciadv.adk2506

Read the full article here.


A molecular perspective on the invasibility of the southern ocean benthos: The impact of hypoxia and temperature on gene expression

Abstract. 

"When an organism makes a long-distance transition to a new habitat, the associated environmental change is often marked and requires physiological plasticity of larvae, juveniles, or other migrant stages. Exposing shallow-water marine bivalves (Aequiyoldia cf. eightsii) from southern South America (SSA) and the West Antarctic Peninsula (WAP) to changes in temperature and oxygen availability, we investigated changes in gene expression in a simulated colonization experiment of the shores of a new continent after crossing of the Drake Passage, and in a warming scenario in the WAP. [...]".

 

Source: Frontiers
Authors: Mariano Martínez et al.
DOI: https://doi.org/10.3389/fphys.2023.1083240

Read the full article here.


On anomalously high sub-surface dissolved oxygen in the Indian sector of the Southern Ocean

Abstract.

"The Southern Ocean (SO) plays a critical role in global ocean productivity and carbon cycling. Bio-Argo floats deployed in the Indian sector of the Southern Ocean provides new insights into the biogeochemical processes. Here we report significantly higher dissolved oxygen (DO) (~ 310 μmol/kg) in summer of 2014–2015 for one float (F1) and winter of 2014 in other float (F2) at sub-surface layer in the subantarctic region of the SO. The summer DO peak in F1 was 10% higher than those during the summer of succeeding year, while the winter DO peak in F2 was 20% higher than those during the winter of succeeding year. [...]".

 

Source: Journal of Oceanography 
Authors: Prince Prakash et al.
DOI: https://doi.org/10.1007/s10872-022-00644-7 

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Impact of the Agulhas Return Current on the oceanography of the Kerguelen Plateau region, Southern Ocean, over the last 40 kyrs

Abstract.

"The oceanography of the western Indian sector of the Southern Ocean is extremely complex due to the presence of several subantartic islands and plateaus that alter the zonal flow of the Antarctic Circumpolar Current. The circulation is even more complex around the Kerguelen Islands (KI) as the hydrological fronts merge with the Agulhas Return Current, the latter transporting warm surface waters from the low latitudes to the Subantarctic Zone (SAZ) east of KI. Here we present new sea-surface and sub-surface temperatures, based on diatom and radiolarian census[...]"

 

Source: Science Direct
Authors: M.Civel-Mazens et al.
DOI:https://doi.org/10.1016/j.quascirev.2020.106711

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Wind, waves, and surface currents in the Southern Ocean: observations from the Antarctic Circumnavigation Expedition

Abstract.

"The Southern Ocean has a profound impact on the Earth's climate system. Its strong winds, intense currents, and fierce waves are critical components of the air–sea interface and contribute to absorbing, storing, and releasing heat, moisture, gases, and momentum. Owing to its remoteness and harsh environment, this region is significantly undersampled, hampering the validation of prediction models and large-scale observations from satellite sensors. Here, an unprecedented data set of simultaneous observations of wind [...]"

 

Source: Earth System Science Data
Authors: Marzieh H. Derkani et al.
DOI: https://doi.org/10.5194/essd-13-1189-2021

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Small phytoplankton contribute greatly to CO2-fixation after the diatom bloom in the Southern Ocean

Abstract.

"Phytoplankton is composed of a broad-sized spectrum of phylogenetically diverse microorganisms. Assessing CO2-fixation intra- and inter-group variability is crucial in understanding how the carbon pump functions, as each group of phytoplankton may be characterized by diverse efficiencies in carbon fixation and export to the deep ocean. We measured the CO2-fixation of different groups of phytoplankton at the single-cell level around the naturally iron-fertilized Kerguelen plateau (Southern Ocean)[...]"

 

Source: The ISME Journal 
Authors: Solène Irion et al
DOI: https://doi.org/10.1038/s41396-021-00915-z

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Southern Ocean carbon export efficiency in relation to temperature and primary productivity

Abstract.

"Satellite remote sensing and numerical models are widely used to estimate large-scale variations in ocean carbon export, but the relationship between export efficiency (e-ratio) of sinking organic carbon out of the surface ocean and its drivers remains poorly understood, especially in the Southern Ocean. Here, we assess the effects of temperature and primary productivity on e-ratio by combining particulate organic carbon export flux from in situ measurements during 1997–2013, environmental parameters from satellite products, and outputs from ocean biogeochemical models in the Southern Ocean. Results show that “High Productivity Low E-ratio” (HPLE) is a common phenomenon in the Subantarctic Zone and the Polar Frontal Zone, but not the Antarctic Zone[...]"

 

Source: Nature Scientific Reports
Authors: Gaojing Fan et al.
DOI: https://doi.org/10.1038/s41598-020-70417-z 

Read the full article here.


Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates

Abstract.

"High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic CO2 emissions continue. Marine microbes are an essential part of the marine food web and are a critical link in biogeochemical processes in the ocean, such as the cycling of nutrients and carbon. Despite this, the response of Antarctic marine microbial communities to ocean acidification is poorly understood. We investigated the effect of increasing fCO2 on the growth of heterotrophic nanoflagellates (HNFs), nano- and picophytoplankton, and prokaryotes (heterotrophic Bacteria and Archaea) in a natural coastal Antarctic marine microbial community from Prydz Bay, East Antarctica.[...]"

 

Source: Biogeosciences
Authors: Stacy Deppeler et al.
DOI: 10.5194/bg-17-4153-2020

Read the  full article here.

 

 


Importance of wind and meltwater for observed chemical and physical changes in the Southern Ocean

Abstract.

"The Southern Ocean south of 30° S represents only one-third of the total ocean area, yet absorbs half of the total ocean anthropogenic carbon and over two-thirds of ocean anthropogenic heat. In the past, the Southern Ocean has also been one of the most sparsely measured regions of the global ocean. [...]"

Source: Nature Geoscience
Authors: Ben Bronselaer et al.
DOI: 10.1038/s41561-019-0502-8

Read the full article here.


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