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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.


Interactive effects of ocean deoxygenation and acidification on a coastal fish Sillago japonica in early life stages

Abstract.

"Acidification and deoxygenation are major threats to ocean environments. Despite the possibilities of their co-occurrence, little is known about their interactive effects on marine organisms. The effects of low pH and low dissolved oxygen (DO) on the early life stages of the coastal fish Sillago japonica were investigated. Twenty-five experimental treatments fully crossed in five levels of pH 7.6–8.1 and DO 50–230 μmol/kg (20–100 % saturation degree) were tested, and hatching rate of the embryos and survivability of the larvae after 24 h at 25 °C were investigated. [...]".

 

Source: Science Direct 
Authors: Makiko Yorifuji et al.
DOI: https://doi.org/10.1016/j.marpolbul.2023.115896

Read the full article here.


A Reconstructing Model Based on Time–Space–Depth Partitioning for Global Ocean Dissolved Oxygen Concentration

Abstract.

"Dissolved oxygen (DO) is essential for assessing and monitoring the health of marine ecosystems. The phenomenon of ocean deoxygenation is widely recognized. Nevertheless, the limited availability of observations poses a challenge in achieving a comprehensive understanding of global ocean DO dynamics and trends. The study addresses the challenge of unevenly distributed Argo DO data by developing time–space–depth machine learning (TSD-ML), a novel machine learning-based model designed to enhance reconstruction accuracy in data-sparse regions. [...]".

 

Source: MDPI
Authors: Zhenguo Wang et al.
DOI: https://doi.org/10.3390/rs16020228

Read the full article here.


High-frequency dynamics of pH, dissolved oxygen, and temperature in the coastal ecosystems of the Tanga-Pemba Seascape...

Full title: "High-frequency dynamics of pH, dissolved oxygen, and temperature in the coastal ecosystems of the Tanga-Pemba Seascape: implications for upwelling-enhanced ocean acidification and deoxygenation"

Abstract.

"Ocean acidification, deoxygenation, and warming are three interconnected global change challenges caused by increased anthropogenic carbon emissions. These issues present substantial threats to marine organisms, ecosystems, and the survival of coastal communities depending on these ecosystems. Coastal upwelling areas may experience significant [...]".

 

Source: Frontiers in Marine Science
Authors: Rushingisha George et al. 
DOI: https://doi.org/10.3389/fmars.2023.1286870

Read the full article here.


Reconstruction of dissolved oxygen in the Indian Ocean from 1980 to 2019 based on machine learning techniques

Abstract.

"Oceanic dissolved oxygen (DO) decline in the Indian Ocean has profound implications for Earth’s climate and human habitation in Eurasia and Africa. Owing to sparse observations, there is little research on DO variations, regional comparisons, and its relationship with marine environmental changes in the entire Indian Ocean. In this study, we applied different machine learning algorithms to fit regression models between measured DO, ocean reanalysis physical variables, and spatiotemporal variables. [...]".

 

Source: Frontiers in Marine Science
Authors: Sheng Huang et al.
DOI: https://doi.org/10.3389/fmars.2023.1291232

Read the full article here.


Ocean deoxygenation caused non-linear responses in the structure and functioning of benthic ecosystems

Abstract.

"The O2 content of the global ocean has been declining progressively over the past decades, mainly because of human activities and global warming. Nevertheless, how long-term deoxygenation affects macrobenthic communities, sediment biogeochemistry and their mutual feedback remains poorly understood. Here, we evaluate the response of the benthic assemblages and biogeochemical functioning to decreasing O2 concentrations along the persistent bottom-water dissolved O2 gradient of the Estuary and Gulf of St. Lawrence (QC, Canada). [...]".

 

Source: Wiley Online Library
Authors: Ludovic Pascal et al.
DOI: https://doi.org/10.1111/gcb.16994

Read the full article here.


Simulations of ocean deoxygenation in the historical era: insights from forced and coupled models

Abstract.

"Ocean deoxygenation due to anthropogenic warming represents a major threat to marine ecosystems and fisheries. Challenges remain in simulating the modern observed changes in the dissolved oxygen (O2). Here, we present an analysis of upper ocean (0-700m) deoxygenation in recent decades from a suite of the Coupled Model Intercomparison Project phase 6 (CMIP6) ocean biogeochemical simulations. The physics and biogeochemical simulations include both ocean-only (the Ocean Model Intercomparison Project Phase 1 and 2, OMIP1 and OMIP2) and coupled Earth system (CMIP6 Historical) configurations. [...]".

 

Source: Frontiers in Marine Science 
Authors: Yohei Takano et al.
DOI: https://doi.org/10.3389/fmars.2023.1139917

Read the full article here.


On the Origins of Open Ocean Oxygen Minimum Zones

Abstract.

"Recent work suggests that Oxygen Minimum Zones (OMZs) are sustained by the supply of oxygen-poor waters rather than the export of organic matter from the local surface layer and its subsequent remineralization inside OMZs. However, the mechanisms that form and maintain OMZs are not well constrained, such as the origin of the oxygen that oxygenates OMZs, and the locations where oxygen consumption occurs. Here we use an observation-based transport matrix to determine the origins of open ocean OMZs in terms of (a) OMZ volume, (b) oxygen that survives remineralization and oxygenates OMZs, and (c) oxygen utilization in the interior ocean that contributes to the oxygen-deficit of OMZs. [...]".

 

Source: Wiley Online Library
Authors: Xabier Davila et al.
DOI: https://doi.org/10.1029/2023JC019677

Read the full article here.

 


GOBAI-O2: temporally and spatially resolved fields of ocean interior dissolved oxygen over nearly 2 decades

Abstract.

"For about 2 decades, oceanographers have been installing oxygen sensors on Argo profiling floats to be deployed throughout the world ocean, with the stated objective of better constraining trends and variability in the ocean's inventory of oxygen. Until now, measurements from these Argo-float-mounted oxygen sensors have been mainly used for localized process studies on air–sea oxygen exchange, upper-ocean primary production, biological pump efficiency, and oxygen minimum zone dynamics. Here, we present a new four-dimensional gridded product of ocean interior oxygen, derived via machine learning algorithms trained on dissolved oxygen [...]".

 

Source: Earth System Science Data
Authors: Jonathan D. Sharp et al.
DOI: https://doi.org/10.5194/essd-15-4481-2023

Read the full article here.


Monsoon-driven seasonal hypoxia along the northern coast of Oman

Abstract.

"Dissolved oxygen and current observations from a cabled ocean observatory in the Sea of Oman show that the annual recurrence of coastal hypoxia, defined as dissolved oxygen concentrations ≤63 μM, is associated with the seasonal cycle of local monsoon winds. The observations represent the first long-term (5+ years) continuous moored observations off the northern Omani coast. During the summer/fall southwest (SW) monsoon season (Jun-Nov), winds in the Sea of Oman generate ocean currents that result in coastal upwelling of subsurface waters with low dissolved oxygen concentrations. [...]".

 

Source: Frontiers in Marine Science
Authors: Steven F. DiMarco et al.
DOI: https://doi.org/10.3389/fmars.2023.1248005

Read the full article here.


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