Abstract.

"Marine Oxygen Minimum Zones (OMZs) modulate biogeochemical cycles, and directly impact climate dynamics by influencing air-sea fluxes of the potent greenhouse gases methane and nitrous oxide (Levin, 2018). OMZs are formed in regions of weak oxygen (O2) supply from physical ventilation and high integrated microbial O2 demand fueled by downward organic flux from overlying surface waters. The ocean’s major OMZs are found in the Eastern Tropical South and North Pacific Ocean and the Arabian Sea and Bay of Bengal in the Indian Ocean (Karstensen et al., 2008; Stramma et al., 2008). [...]".

Source: Frontiers in Marine Science
Authors: Annie Bourbonnais et al.
DOI: https://doi.org/10.3389/fmars.2023.1333731

Read the full article here.

Abstract.

"Late Devonian (ca. 360 Ma), Early Carboniferous (ca. 330 Ma), and Early Triassic (ca. 250 Ma) manganese deposits in the South China Block support an emerging view that some Mn carbonates form through direct synsedimentary (authigenic) precipitation. These Mn carbonates accumulated on distal shelves and are interbedded with lime mudstone and heterozoan carbonates that accumulated in coastal upwelling environments. Lithofacies, Ce anomalies combined with vanadium, uranium, and molybdenum enrichments indicate that the Mn carbonates were primarily precipitated under anoxic conditions. [...]".

Source: Science Direct 
Authors: Fangge Chen et al.
DOI: https://doi.org/10.1016/j.epsl.2023.118385

Read the full article here.

Full title: "Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan"

Abstract.

"Coastal warming, acidification, and deoxygenation are progressing primarily due to the increase in anthropogenic CO2. Coastal acidification has been reported to have effects that are anticipated to become more severe as acidification progresses, including inhibiting the formation of shells of calcifying organisms such as shellfish, which include Pacific oysters (Crassostrea gigas) [...]".

Source: Biogeosciences
Authors: Masahiko Fujii et al.
DOI: https://doi.org/10.5194/bg-20-4527-2023

Read the full article here.

Abstract.

"The early Toarcian of the Early Jurassic saw a long-term positive carbon-isotope excursion (CIE) abruptly interrupted by a significant negative excursion (nCIE), associated with rapid global warming and an oceanic anoxic event (T-OAE, ∼183 Ma). However, the detailed processes and mechanisms behind widespread ocean deoxygenation are unclear. Here, we present high-resolution carbonate-associated sulfate sulfur-isotope [...]".

Source: Science Direct
Authors: Zhong Han et al.
DOI: https://doi.org/10.1016/j.epsl.2023.118404

Read the full article here.

Title: "Microbially-Driven Shifts in Marine Nutrient Cycling in Response to Ocean Deoxygenation and Climate Change"

Speaker: Julia Huggins

Event Date: Tuesday, 5 December 2023, 12:00 - 13:00 h EST

"The oceans are currently losing dissolved oxygen (O2) as a result of climate change and human activity, which may have dramatic effects on biodiversity and global climate feedbacks. As O2 is depleted to near-anoxia in pelagic marine environments, microorganisms shift from aerobic respiration to anaerobic nitrogen-based metabolisms. Most conceptual and numerical models assume this shift will lead to nitrogen loss, but it can also lead to nitrogen retention depending on which microbial metabolism(s) engage. The controls regulating the relative activity and variability of these metabolisms remain uncertain, however, and this confounds our efforts to predict how the marine nitrogen cycle responds to deoxygenation and impacts other marine biogeochemical cycles. I conduct experiments with live marine microbial communities to measure how different nitrogen-based microbial metabolisms are regulated in the transition from oxic to anoxic conditions. I use a combination of stable nitrogen isotopes (15N) and bioinformatics technologies to increase our knowledge of how competing microbial metabolisms are regulated under variable environmental conditions and unstable resource availability. My work has implications for our biogeochemical models that predict ocean deoxygenation and related climate feedbacks."

You can find more information here and you can join the webinar here.

Title: "Sailing for oxygen - how citizen science can help understand ocean deoxygenation"

Event Date: Thursday, 7 December 2023, 13:00 - 14:00 h

"On Thursday 7 December 2023, EMB will host its 35th Third Thursday Science Webinar featuring Toste Tanhua who will speak about "Sailing for oxygen - how citizen science can help understand ocean deoxygenation".

This topic is linked to the science within the EMB Future Science Brief No. 10 'Ocean oxygen: the role of the Ocean in the oxygen we breathe and the threat of deoxygenation'.

Toste Tanhua is a Senior Scientist at GEOMAR (Germany) and chemical oceanographer. His work focuses on Ocean ventilation by observing transient tracers and conducting deliberate tracer release experiments to understand ventilation and mixing in the Ocean. He also works on understanding the dynamics of Ocean carbon, nutrients and oxygen. In addition, he is co-chairing the steering committee of the Global Ocean Observing System (GOOS) and coordinating the EU funded project EuroSea, that aims at improving the ocean observing and forecasting system."

You can find more information here and you can register for the webinar here.

Abstract.

"Atmospheric oxygen (O2) concentrations likely remained below modern levels until the Silurian–Devonian, as indicated by several recent studies. Yet, the background redox state of early Paleozoic oceans remains poorly constrained, hampering our understanding of the relationship between early animal evolution and O2. Here, we present a multi-proxy analysis of redox conditions in the Caledonian foreland basin to Baltica from the early to the mid-Silurian. [...]".

Source: Science Direct 
Authors: Emma R. Haxen et al.
DOI: https://doi.org/10.1016/j.epsl.2023.118416

Read the full article here.

Intro.

"UNESCO’s Intergovernmental Oceanographic Commission (IOC/UNESCO), El Centro de Estudios Avanzados en Zonas Áridas (CEAZA) and the Universidad Catolica del Norte, as well as many other partners and sponsors organized the GOOD-OARS-CLAP-COPAS Summer School from 6-12 November 2023 in La Serena, Chile, to teach the latest science of ocean acidification and deoxygenation."

Source: IOC-UNESCO

For further information, please read here. 

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.

Abstract.

"The occurrences of summer hypoxia in coastal California Current can significantly affect the benthic and pelagic habitat and lead to complex ecosystem changes. Model-simulated hypoxia in this region is strongly spatially heterogeneous, and its future changes show uncertainties depending on the model used. Here, we used an ensemble of the new generation Earth system models to examine the present-day and future changes of summer hypoxia in this region. We applied model-specific thresholds combined with empirical bias adjustments of the dissolved oxygen variance to identify hypoxia. [...]".

Source: Frontiers in Marine Science 
Authors: Hui Shi et al.
DOI: https://doi.org/10.3389/fmars.2023.1205536

Read the full article here.