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Oxygen Seasonality, Utilization Rate, and Impacts of Vertical Mixing in the Eighteen Degree Water Region of the Sargasso Sea as Observed by Profiling

Abstract.

"Seasonal oxygen structure and utilization in the Sargasso Sea are characterized using nine profiling floats with oxygen 2021 sensors (years 2005–2008), deployed in an Eighteen Degree Water (EDW) experiment (CLIMODE). During autumn-winter when the mixed layer is deepening, oxygen increases from the surface to the base of the EDW at 400 m. During spring-summer, oxygen decreases except between the seasonal pycnocline and compensation depth, creating the seasonal shallow oxygen maximum layer (SOMax) with oxygen production[...]"

 

Source: Advancing Earth and Space Science
Authors: Samuel J. Billheimer et al.
DOI: https://doi.org/10.1029/2020GB006824

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Response of benthic nitrogen cycling to estuarine hypoxia

Abstract.

"The effects of bottom water oxygen concentration on sediment oxygen uptake, oxygen penetration depth, nitrate and ammonium fluxes, anammox, denitrification, dissimilatory nitrate reduction to ammonium, nitrification, and mineralization were investigated off the Changjiang estuary and its adjacent East China Sea, by combining a seasonal comparison[...]"

 

Source: ASLO- Association for the Sciences Limnology and Oceanography
Authors: Guodong Song et al.
DOI: https://doi.org/10.1002/lno.11630

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A benthic oxygen oasis in the early Neoproterozoic ocean

Abstract.

"Benthic oxygen oases linked to photosynthetic mats have been reported in modern anoxic aquatic systems. Benthic macroalgal blooms were common in stratified, anoxic Neoproterozoic oceans, leading us to hypothesize the existence of benthic oxygen oases at that time. This hypothesis has significant implications regarding the bioavailability of transition metals (e.g., Cu, Zn, Ni, Mo, V) and the distribution of aerobic eukaryotes in these oceans[...]"

 

Source: Science Direct
Authors: Haiyang Wang et al.
DOI: https://doi.org/10.1016/j.precamres.2020.106085

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Environmental Drivers of Mesophotic Echinoderm Assemblages of the Southeastern Pacific Ocean

Abstract.

"Mesophotic ecosystems (50–400 m depth) of the southeastern Pacific have rarely been studied because of the logistical challenges in sampling across this remote zone. This study assessed how oxygen concentrations and other environmental predictors explain variation in echinoderm assemblages at these mesophotic systems, where this group is among the predominant fauna. We compiled data on echinoderm taxa at 91 sampling stations, from historical and recent surveys (between 1950 and 2019), covering a longitudinal gradient of approximately 3,700 km along with the Nazca, Salas y Gómez[...]"

 

Source: Frontiers in Marine Science
Authors: Ariadna Mecho et al.
DOI: 10.3389/fmars.2021.574780

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A benthic oxygen oasis in the early Neoproterozoic ocean

Abstract.

"Benthic oxygen oases linked to photosynthetic mats have been reported in modern anoxic aquatic systems. Benthic macroalgal blooms were common in stratified, anoxic Neoproterozoic oceans, leading us to hypothesize the existence of benthic oxygen oases at that time. This hypothesis has significant implications regarding the bioavailability of transition metals (e.g., Cu, Zn, Ni, Mo, V) and the distribution of aerobic eukaryotes in these oceans. However, little research has been directed toward testing the benthic oxygen[...]"

 

Source: Science Direct
Authors:Haiyang Wang et al.
DOI: https://doi.org/10.1016/j.precamres.2020.106085

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Fossil evidence for vampire squid inhabiting oxygen-depleted ocean zones since at least the Oligocene

Abstract.

"A marked 120 My gap in the fossil record of vampire squids separates the only extant species (Vampyroteuthis infernalis) from its Early Cretaceous, morphologically-similar ancestors. While the extant species possesses unique physiological adaptations to bathyal environments with low oxygen concentrations, Mesozoic vampyromorphs inhabited epicontinental shelves. However, the timing of their retreat towards bathyal and oxygen-depleted habitats is poorly documented. Here, we document a first record of a post-Mesozoic vampire squid from the Oligocene of the Central Paratethys[...]"

Source: Nature - Communications Biology
Authors: Martin Košťák et al.
DOI: https://doi.org/10.1038/s42003-021-01714-0

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Triple Oxygen Isotopes in Silica–Water and Carbonate–Water Systems

Abstract.

"The field of stable isotope geochemistry began with the recognition that the oxygen isotope composition of ancient carbonates could be used as a paleothermometer (Urey 1947; Urey et al. 1951). As stated by Urey (1947), “Accurate determinations of the Ol8 content of carbonate rocks could be used to determine the temperature at which they were formed”. This concept was based on the temperature dependence for the oxygen isotope fractionation between calcite and water. Urey realized that if a mass spectrometer with sufficient precision could be built, a method of reproducibly extracting oxygen from[...]"

 

Source: Reviews in Mineralogy and Geochemistry
Authors: Jordan A.G. Wostbrock et al.
DOI: https://doi.org/10.2138/rmg.2021.86.11

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The rise of angiosperms strengthened fire feedbacks and improved the regulation of atmospheric oxygen

Abstract.

"The source of oxygen to Earth’s atmosphere is organic carbon burial, whilst the main sink is oxidative weathering of fossil carbon. However, this sink is to insensitive to counteract oxygen rising above its current level of about 21%. Biogeochemical models suggest that wildfires provide an additional regulatory feedback mechanism. However, none have considered how the evolution of different plant groups through time have interacted with this feedback. The Cretaceous Period[...]"

 

Source: Nature Geoscience
Authors: Claire M. Belcher et al.
DOI: https://doi.org/10.1038/s41467-020-20772-2

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Assimilating synthetic Biogeochemical-Argo and ocean colour observations into a global ocean model to inform observing system design

Abstract.

"A set of observing system simulation experiments was performed. This assessed the impact on global ocean biogeochemical reanalyses of assimilating chlorophyll from remotely sensed ocean colour and in situ observations of chlorophyll, nitrate, oxygen, and pH from a proposed array of Biogeochemical-Argo (BGC-Argo) floats. Two potential BGC-Argo array distributions were tested: one for which biogeochemical sensors are placed on all current Argo floats and one for which biogeochemical sensors are placed on a quarter of current Argo floats. Assimilating BGC-Argo data greatly improved model results throughout the water column[...]"

 

Source: Biogeosciences
Authors: David Ford et al.
DOI: https://doi.org/10.5194/bg-18-509-2021

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Recent Changes in Deep Ventilation of the Mediterranean Sea; Evidence From Long-Term Transient Tracer Observations

Abstract.

"The Mediterranean Sea is a small region of the global ocean but with a very active overturning circulation that allows surface perturbations to be transported to the interior ocean. Understanding of ventilation is important for understanding and predicting climate change and its impact on ocean ecosystems. To quantify changes of deep ventilation, we investigated the spatiotemporal variability of transient tracers (i.e., CFC-12 and SF6) observations combined with temporal evolution of hydrographic and oxygen observations in the Mediterranean Sea from 13 cruises conducted during 1987–2018, with emphasize on the update from 2011 to 2018. Spatially, both the Eastern and Western Mediterranean Deep Water (EMDW and WMDW) show a general west-to-east gradient[...]"

Source: Frontiers
Authors: Pingyang Li et al.
DOI: https://doi.org/10.3389/fmars.2020.00594

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