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Increasing ocean stratification over the past half-century

Abstract.

"Seawater generally forms stratified layers with lighter waters near the surface and denser waters at greater depth. This stable configuration acts as a barrier to water mixing that impacts the efficiency of vertical exchanges of heat, carbon, oxygen and other constituents. Previous quantification of stratification change has been limited to simple differencing of surface and 200-m depth changes and has neglected the spatial complexity of ocean density change. Here, we quantify changes in ocean stratification down[...]"

 

Source: Nature Climate Change
Authors: Guancheng Li  et al.
DOI: https://doi.org/10.1038/s41558-020-00918-2

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Benthic fluxes of oxygen and heat from a seasonally hypoxic region of Saanich Inlet fjord observed by eddy covariance

Abstract.

"Benthic habitats within fjords are predominantly insulated from the high energy physical dynamics of open coastlines. As a result, fjords may have atypical mass and heat transfer rates at the seafloor. This study presents aquatic eddy covariance (EC) measurements made continuously from late May 2013 through December 2013, in Saanich Inlet fjord, British Columbia, to assess areal-averaged benthic fluxes of dissolved oxygen and heat, and their relationships to bottom boundary layer dynamics and water properties. The measurements were achieved by the connection of a system of underwater EC sensors to Ocean Network Canada's Victoria Experimental Network Under the Sea (VENUS) observatory that has a primary seafloor node[...]"

 

Source: Science Direct
Authors: Clare E. Reimers et al.
DOI: https://doi.org/10.1016/j.ecss.2020.106815

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Metabolic trait diversity shapes marine biogeography

Abstract.

"Climate and physiology shape biogeography, yet the range limits of species can rarely be ascribed to the quantitative traits of organisms1,2,3. Here we evaluate whether the geographical range boundaries of species coincide with ecophysiological limits to acquisition of aerobic energy4 for a global cross-section of the biodiversity of marine animals. We observe a tight correlation between the metabolic rate and the efficacy of oxygen supply, and between the temperature sensitivities[...]"

 

Source: Nature
Authors: Curtis Deutsch et al.
DOI: https://doi.org/10.1038/s41586-020-2721-

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The Northeast Atlantic is running out of excess carbonate in the horizon of cold-water corals communities

Abstract.

"The oceanic uptake of atmospheric carbon dioxide (CO2) emitted by human activities alters the seawater carbonate system. Here, the chemical status of the Northeast Atlantic is examined by means of a high-quality database of carbon variables based on the GO-SHIP A25 section (1997–2018). The increase of atmospheric CO2 leads to an increase in ocean anthropogenic carbon (Cant) and a decrease in carbonate that is unequivocal in the upper and mid-layers (0–2,500 m depth). In the mid-layer, the carbonate content in the Northeast Atlantic is maintained by the interplay between the northward spreading of recently conveyed Mediterranean Water with excess of carbonate and the arrival of subpolar-origin waters close to carbonate[...]".

Source: Nature Reviews Earth & Environment
Authors: Marcos Fontela et al.
DOI: https://doi.org/10.1038/s41598-020-71793-2

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