Abstract.

"Oceanic anoxic events (OAEs) are historical intervals of global-scale ocean deoxygenation associated with hyperthermal climate states and biological crises. Massive volcanic carbon dioxide (CO2) emissions frequently associated with these events are thought to be a common driver of ocean deoxygenation through several climate-warming-related mechanisms. The Early Cretaceous OAE1a is one of the most intense ocean deoxygenation events, persisting for more than 1 Myr (refs.). [...]".

Source: Nature
Authors: Kohen W. Bauer et al.
DOI: https://doi.org/10.1038/s41586-024-07876-1

Read the full article here.

Deadline: 23 October 2024

"The Global Ocean Oxygen Network expert working group is seeking nominations for new members to join in place of several incumbent members that are rotating out in the next 6-12 months.

Over a 3-year term, with the possibility to extend to two terms, GO₂NE members advise the IOC-UNESCO Secretariat and its Member States on the threat of oxygen loss in the ocean and related scientific priorities. GO₂NE is committed to providing a global and multidisciplinary view of ocean deoxygenation, with a focus on understanding its multiple aspects and impacts. Furthermore, GO₂NE developed the framework of the Global Ocean Oxygen Decade (GOOD) as part of the UN Decade of Ocean Science for Sustainable Development, which is working to provide knowledge for action and develop mitigation and adaptation strategies and solutions to ensure continued provision of ecosystem services. More on GO₂NE and GOOD can be found on their respective webpages. 

The call is open to anyone that can demonstrate a strong interest in oxygen in the marine environment. Preference will be given to nominees with experience in biological oceanography, socio-economics, and social science.

To nominate yourself or someone else, please submit your nomination to the GO₂NE Secretariat by 23 October 2024 with the following information:

• Name, affiliation & email address
• A statement of expertise and experience pertaining to ocean oxygen (300 words)
• A statement of suitability to sit on an international scientific steering committee (300 words)

The current GO₂NE members will consider the candidates that fit best to enhance GO₂NE’s global representation of all aspects of research on ocean deoxygenation. We will inform the nominees of the results of the selection process by mid December 2024. GO₂NE actively encourages applications from under-represented groups and is committed to diversity and gender balance. For inquires or more information, please contact the GO₂NE Secretariat."

The 5th Issue of GOOD News is now available here. 

Previous issues are available in the archive here.

Abstract.

"The world’s oceans are under threat from the prevalence of heatwaves caused by climate change. Despite this, there is a lack of understanding regarding their impact on seawater oxygen levels - a crucial element in sustaining biological survival. Here, we find that heatwaves can trigger low-oxygen extreme events, thereby amplifying the signal of deoxygenation. By utilizing in situ observations and state-of-the-art climate model simulations, we provide a global assessment of the relationship between the two types of extreme events in the surface ocean (0–10 m). [...]".

Source: Nature
Authors: Changyu Li et al.
DOI: https://doi.org/10.1038/s41467-024-51323-8

Read the full article here.

Abstract.

"The role of environmental change as a significant force driving biological evolution during the Ediacaran–Cambrian transition remains a subject of extensive debate. In this study, we present high-resolution C-isotope data of organic matter (δ¹³C_org) and multiple S-isotope compositions of pyrite (δ³⁴S_py and Δ³³S_py) obtained from a continuous drill core (ZK1505) in South China, spanning the interval from the Ediacaran to Cambrian Stage 2. [...]".

Source: Science Direct
Authors: Yizhe Gong et al.
DOI: https://doi.org/10.1016/j.palaeo.2024.112281

Read the full article here.

Abstract.

"The expansion of transient and permanent coastal benthic anoxia is one of the most severe problems for the coastal ocean globally. We report frequent, hidden hypoxia in the bottom 5 cm of the water column of a coastal site in the central Baltic Sea by continuous high-resolution profiling of oxygen (O2) directly above the sediment surface. This hypoxia stood in stark contrast to 30-yr O2 monitoring records at this site that suggest apparent continuous well-oxygenated conditions. [...]".

Source: Wiley Online Library
Authors: Jonas Patrik Fredriksson et al.
DOI: https://doi.org/10.1002/lno.12607

Read the full article here.

Abstract.

"Dissolved oxygen (DO) is one of the core parameters in ocean investigation among various disciplines. The Winkler method, a classical approach, is extensively employed for DO determination. This method uses the reaction of Mn²⁺ to I₃^‐− as a proxy to quantitatively convert DO to iodine, followed by titration with sodium thiosulfate solution. However, this method is time-consuming and laborious due to the shaking and/or re-shaking of the DO bottle after adding the pickling reagents and waiting for the precipitate to settle. [...]".

Source: Science Direct
Authors: Yuhan Zhang et al.
DOI: https://doi.org/10.1016/j.seares.2024.102513

Read the full article here.

Full title: "Measuring deoxygenation effects on marine predators: A new animal-attached archival tag recording in situ dissolved oxygen, temperature, fine-scale movements and behaviour"

Abstract.

"1. Global climate-driven ocean warming has decreased dissolved oxygen (DO) levels (ocean deoxygenation) leading to expansions of hypoxic zones, which will affect the movements, behaviour, physiology and distributions of marine animals. However, the precise responses of animals to low DO remains poorly understood because movements and activity levels are seldom recorded alongside instantaneous DO in situ. [...]".

Source: Wiley Online Library
Authors: Ivo da Costa et al.
DOI: https://doi.org/10.1111/2041-210X.14360

Read the full article here.

Abstract.

"Eastern boundary upwelling systems (EBUS) are ecologically and economically important marine regions of the world ocean. In these systems, zooplankton play a pivotal role in transferring primary production up through the food web. Recent studies show that global warming is causing a gradual deoxygenation of the world ocean, while in EBUS a vertical expansion of the subsurface oxygen minimum zone (OMZ) along with increased wind-driven upwelling are taking place, further exacerbating hypoxic conditions for zooplankton inhabiting the upwelling zone. Hypoxia can affect zooplankton by disrupting their respiration, migration, reproduction, and development. [...]".

Source: EGUsphere 
Authors: Leissing Frederick et al.
DOI: https://doi.org/10.5194/egusphere-2024-836

Read the full article here.

Session 15: Ocean deoxygenation: drivers, trends, and biogeochemical-ecosystem impacts 
Xiamen Symposium on Marine Environmental Sciences 2025 (XMAS 2025) in Xiamen, China
January 14th to 17th, 2025

"XMAS 2025 consists of interdisciplinary cutting-edged sessions covering physical, chemical, and biological oceanography as well as marine pollution. In addition, workshops on emerging topics in marine environmental sciences such as ocean-based carbon dioxide removal, ocean governance and sustainability, the marine economy, marine education and outreach, and special sessions on Women in Science and mentoring future scientists will also be offered. More sessions and updates can be found on the XMAS 2025 website: https://melmeeting.xmu.edu.cn/xmas/#. 

The abstract submission is open by September 20^th, 2024, 18:00 CET on https://xmas.aconf.org/control.php/submission/submission_add.html. Your contribution to either session is welcomed."

Abstract.

"We examine how oxygen levels and the choice of 16S ribosomal RNA (rRNA) tags impact marine bacterial communities using Next-Generation amplicon sequencing. Analyzing V3 and V6 regions, we assess microbial composition in both Oxygen minimum zones (OMZ) and non-OMZ (NOMZ) areas in the Arabian Sea (AS) and the Central Indian Ocean basin (CIOB) respectively. Operational taxonomic units (OTUs) at 97% similarity showed slightly higher richness and diversity with V6 compared to V3. Vertical diversity patterns were consistent across both regions. [...]".

Source: Science Direct
Authors: Mandar Bandekar et al.
DOI: https://doi.org/10.1016/j.marenvres.2024.106615

Read the full article here.

Abstract.

"Dissolved oxygen (DO) is one of the most important drivers of ocean biogeochemical cycles and marine life, and in many areas its concentration has declined due to climate change. In recent decades, a growing number of autonomous oceanographic platforms has been equipped with sensors for direct in situ measurements of oxygen levels. However, to ensure high quality and comparable data, these observations need to be validated or, if necessary, corrected. In this paper, we compiled all the available DO data collected by Argo floats and gliders in the South Adriatic Pit (Mediterranean Sea) between 2014 and 2020. [...]".

Source: Frontiers in Marine Science
Authors: Riccardo Gerin et al.
DOI: https://doi.org/10.3389/fmars.2024.1373196

Read the full article here.

Abstract.

"The spread of marine anoxia is believed to have played a key role in the development of the SPICE (Steptoean Positive Carbon Isotope Excursion) event and the end-Marjuman extinction in the late Cambrian (∼497.5 m.y. ago), but their cause-and-effect relationship is poorly constrained. Here we present an integrated analysis of carbonate δ13C, cerium anomalies (Ce/Ce*), and genus-level diversity data of trilobites from the North China Platform. [...]".

Source: GeoScienceWorld
Authors: Aihua Yang et al.
DOI: https://doi.org/10.1130/G52200.1

Read the full article here.

Abstract.

"Levels of dissolved oxygen in open ocean and coastal waters are decreasing (ocean deoxygenation), with poorly understood effects on marine megafauna. All of the more than 1000 species of elasmobranchs (sharks, skates, and rays) are obligate water breathers, with a variety of life-history strategies and oxygen requirements. This review demonstrates that although many elasmobranchs typically avoid hypoxic water, they also appear capable of withstanding mild to moderate hypoxia with changes in activity, ventilatory responses, alterations to circulatory and hematological parameters, and morphological alterations to gill structures. [...]".

Source: Wiley Online Library
Authors: Matt J. Waller et al.
DOI: https://doi.org/10.1111/jfb.15830

Read the full article here.

Abstract.

"Oceanic dissolved oxygen (DO) is crucial for oceanic material cycles and marine biological activities. However, obtaining subsurface DO values directly from satellite observations is limited due to the restricted observed depth. Therefore, it is essential to develop a connection between surface oceanic parameters and subsurface DO values. Machine learning (ML) methods can effectively grasp the complex relationship between input attributes and target variables, making them a valuable approach for estimating subsurface DO values based on surface oceanic parameters. [...]".

Source: Science Direct
Authors: Bo Ping et al.
DOI: https://doi.org/10.1016/j.marenvres.2024.106578

Read the full article here.

Abstract.

"Benthic foraminifera are single-celled organisms inhabiting all marine environments. Despite their high tolerance to oxygen depletion, the prevailing hypothesis anticipates a reduction in their diversity in permanently oxygen-depleted environments, including oxygen minimum zones. Here we re-evaluate diversity and study the endemism of benthic foraminifera in the eastern Pacific, an oceanic area hosting the largest permanently oxygen-depleted waters of the world. [...]".

Source: Science Direct
Authors: Paula Diz et al.
DOI: https://doi.org/10.1016/j.pocean.2024.103277

Read the full article here.

Abstract.

"It is predicted that oxygen minimum zones (OMZs) in the ocean will expand as a consequence of global warming and environmental pollution. This will affect the overall microbial ecology and microbial nitrogen cycle. As one of the world's largest alluvial estuaries, the Yangtze Estuary has exhibited a seasonal OMZ since the 1980s. In this study, we have uncovered the microbial composition, the patterns of community assembly and the potential for microbial nitrogen cycling within the water column of the Yangtze Estuary, with a particular focus on OMZ. [...]".

Source: Science Direct
Authors: Yihua Sun et al.
DOI: https://doi.org/10.1016/j.envres.2024.119011

Read the full article here.

Application deadline for PAGES (Past Global Changes) Mobility Fellowships closing on 15 August 2024

"There are two types, one for mobility within Africa and one within Latin America and the Caribbean (LAC).
These fellowships are meant to promote mobility of early career researchers from one country within the region to another country within the same region, typically for one month. Deadline for both is 15 August 2024."

For further information, please visit here for Africa and here for LAC. 

GO₂NE Webinar on Ocean Deoxygenation. 

"Do you want to know more about deoxygenation in the ocean?
Join us for the upcoming webinar!

Thursday, 11th July 2024, 15:30 h – 16:30 CEST

Registration link

Please join the Global Ocean Oxygen Network (IOC Expert Working Group GO2NE) for a new session of its webinar series on ocean deoxygenation. The webinar will feature presentations by two ocean oxygen experts, followed by moderated discussion sessions. Speakers will discuss the latest globally relevant ocean oxygen research in the context of their fields of research and expertise.

If you are interested in presenting at one of the upcoming webinars, please submit a short abstract here.

Moderation: 
Jeremy Sterling
Ocean Science Section, IOC-UNESCO

Speakers:
Houssine Nibani
Integrated Management of East Mediterranean Coastlines (IMAC), Morocco

Simone Moretti
Max Planck Institute for Chemistry, Germany

If you want to receive further information about upcoming webinars, please register here." 

Abstract.

"This study presents a high-resolution record of δ15Nsed, which serves as a proxy for water column denitrification and oxygen minimum zone (OMZ) intensity, from the Soledad Basin in the Eastern Tropical North Pacific OMZ. The Soledad Basin δ15Nsed record is compared to the Pescadero Slope and Santa Barbara Basin (SBB) δ15Nsed records to gain insight into regional variations in the ETNP OMZ. During the Medieval Climate Anomaly (MCA; 950–1250 CE), Soledad Basin, Pescadero Slope, and SBB records exhibit coherent trends suggesting that there was general water column oxygenation stability. [...]".

Source: MDPI
Authors: Caitlin E. Tems & Eric Tappa
DOI: https://doi.org/10.3390/oceans5020021

Read the full article here.

Abstract.

"Microbial communities within oxygen minimum zones (OMZs) play crucial roles in the marine biogeochemical cycling. Arabian Sea (AS) has one of the largest OMZs among the global oceans, however, knowledge about the microbial ecology of the AS OMZ remained limited. In the present study, 44 water samples collected from six stations across the AS, spanning from the deep chlorophyll maximum (DCM) layer to 4000m depth were analyzed. High-throughput sequencing of 16S rRNA genes revealed the structural diversity of bacterial and archaeal communities, influenced primarily by depth and dissolved oxygen (DO) levels. [...]".

Source: Frontiers in Marine Science
Authors: Ding Li et al.
DOI: https://doi.org/10.3389/fmars.2024.1380819

Read the full article here.

Call for Abstracts closing on 31 July 2024

AGU (American Geophysical Union) annual meeting 2024, Washington, D.C., 9-13 December 2024

A session on ocean deoxygenation will be held during the AGU meeting in Washington, D.C., during the second week of December. 

The abstract submission will close on July 31st. 

For further information, please visit here. 

Abstract.

"Respiratory activity in the oceans is declining due to the expansion of hypoxic zones and progressive deoxygenation, posing threats to marine organisms along with impacts of concurrent ocean acidification. Therefore, understanding the combined impacts of reduced pO2 and elevated pCO2 on marine primary producers is of considerable significance. Here, to simulate diatoms’ sinking into the aphotic zone of turbid coastal water, we exposed the diatoms Thalassiosira pseudonana and Thalassiosira weissflogii in darkness at 20°C [...]".

Source: Frontiers in Marine Science
Authors: Jia-Zhen Sun et al.
DOI: https://doi.org/10.3389/fmars.2024.1387552

Read the full article here.

Abstract.

"Reef-building corals live in highly hydrodynamic environments, where water flow largely controls the complex chemical microenvironments surrounding them—the concentration boundary layer (CBL). The CBL may be key to alleviate ocean acidification (OA) effects on coral colonies by partially isolating them. However, OA effects on coral CBL remain poorly understood, particularly under different flow velocities. Here, we investigated these effects on the reef-building corals Acropora cytherea, Pocillopora verrucosa, and Porites cylindrica. [...]".

Source: Nature
Authors: Catarina P. P. Martins et al.
DOI: https://doi.org/10.1038/s41598-024-63210-9

Read the full article here.

Abstract.

"Coastal habitats are under increasing anthropogenic pressures that jeopardize the survival and persistence of ecologically important marine life. One such stressor, increasingly recognized as a significant threat to marine coastal habitats, is deoxygenation (Breitburg et al., 2018; IPCC, 2023). The United Nations Decade of Ocean Science for Sustainable Development has identified deoxygenation as a top international priority for ocean research, with efforts being led by the Global Ocean Oxygen Network (GO2NE) and affiliated programs (Global Ocean Oxygen Decade program). [...]".

Source: Frontiers in Marine Science
Authors: Maggie D. Johnson et al.
DOI: https://doi.org/10.3389/fmars.2024.1425902

Read the full article here.

Abstract.

"To assess the consequences of nutrient reduction strategies on water quality under climate change, we investigated the long-term dynamics of dissolved oxygen (DO) and pH in Narragansett Bay (NB), a warming urbanized estuary in Rhode Island, where nitrogen loads have declined due to extensive wastewater treatment plant upgrades. We use 15 years (January 2005-December 2019) of measurements from the Narragansett Bay Fixed Site Monitoring network. Nutrient-enhanced phytoplankton growth can increase DO in the upper water column while subsequent respiration can reduce water column DO and enhance bottom water acidification, and vice-versa. [...]".

Source: Frontiers in Marine Science
Authors: Hongjie Wang et al.
DOI: https://doi.org/10.3389/fmars.2024.1374873

Read the full article here.

Abstract.

"As a consequence of on-going global warming, the ocean is losing oxygen, which has implications not only in terms of marine resources management and food supply but also in terms of the potentially important feedback on the global carbon cycle and climate. Of particular scrutiny are the extended zones of already low levels of oxygen called the oxygen minimum zones (OMZs) embedded in the subsurface waters of the productive Eastern Boundary Upwelling Systems (EBUS). These OMZs are currently diversely simulated by state-of-the-art Earth System Models (ESM) hampering a reliable projection of ocean deoxygenation on marine ecosystem services in these regions. [...]".

Source: Nature 
Authors: Ivan Almendra et al.
DOI: https://doi.org/10.1038/s43247-024-01427-2

Read the full article here.

GO₂NE Webinar on Ocean Deoxygenation. 

"Do you want to know more about deoxygenation in the ocean?
Join us for the upcoming webinar!

Wednesday, 12 June 2024, 15:00 h – 16:00 CEST

Registration link

Join the Global Ocean Oxygen Network (IOC Expert Working Group GO2NE) for a special session of its webinar series on ocean deoxygenation to mark World Ocean Day 2024. The 29th webinar will take place on 12 June 2024, 1500 CEST. The webinar will feature presentations by GO2NE Co-Chairs Andreas Oschlies and Caroline Slomp and expert working group member Karin Limburg, speaking on the latest global scientific efforts to understand, mitigate and adapt to ocean deoxygenation and the most recent work of GO2NE and its members. 

If you are interested in presenting at one of the upcoming webinars, please submit a short abstract here.

Speakers:

Andreas Oschlies (GEOMAR, Germany)
Caroline Slomp (Radboud University, The Netherlands)
Karin Limburg (SUNY College of Environmental Science and Forestry, USA)

If you want to receive further information about upcoming webinars, please register here." 

Abstract.

"Oxygen declination in coastal oceans has accelerated drastically in recent decades, both in terms of severity and spatial extent, and such disappearance of oxygen leads to dead zones where life can't survive. This phenomenon is mainly attributed to nutrient pollution and climate change due to intensified anthropogenic activities. The annual statistical oxygen mean concentrations showed the current deoxygenation trends based on (WOA_2001–2018) data comparison of 200 m below the surface water from the first two decades of the 21st century. [...]".

Source: Science Direct
Authors: Md Mesbah Uddin Bhuiyan et al.
DOI: https://doi.org/10.1016/j.cscee.2024.100621

Read the full article here.

Abstract.

"Recent estimates of the global inventory of dissolved oxygen (DO) have suggested a decrease of 2 % since the 1960s. However, due to the sparse historical oxygen data coverage, the DO inventory exhibits large regional uncertainties at interannual timescale. Using ISASO2, a new DO Argo-based optimally interpolated climatology https://doi.org/10.17882/52367 (Kolodziejczyk et al.,2021), we have estimated an updated regional oxygen inventory. Over the long term (~1980–2013), comparing the ISASO2 Argo fields with the first guess WOA18 built from the DO bottle samples fields extracted from WOD18, the broad tendency to global ocean deoxygenation remains robust in the upper 2000 m with -451±243 Tmol per decade. [...]".

Source: Earth System Science Data
Authors: Nicolas Kolodziejczyk et al.
DOI: https://doi.org/10.5194/essd-2024-106

Read the full article here.

Abstract.

"We conducted extensive sediment trap experiments in the Benguela Upwelling System (BUS) in the south-eastern Atlantic Ocean to study the influence of zooplankton on the flux of particulate organic carbon (POC) through the water column and its sedimentation. Two long term moored and sixteen short term free-floating sediment trap systems were deployed. The mooring experiments were conducted for several years and the sixteen drifters were deployed on three different research cruises between 2019 and 2021. Zooplankton was separated from the trapped material and divided into 8 different zooplankton groups. [...]".

Source: EGUsphere 
Authors: Luisa Chiara Meiritz et al.
DOI: https://doi.org/10.5194/egusphere-2024-700

Read the full article here.

Abstract.

"The Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic) is marked by widespread marine deoxygenation and deposition of organic carbon (OC)-rich strata. The genesis of the T-OAE is thought to be associated with environmental changes caused by the emission of 12C-enriched greenhouse gasses (CO2, CH4), manifested in a negative Toarcian carbon isotope excursion (nT-CIE). The nT-CIE is commonly used to stratigraphically define the T-OAE, and despite the complex interrelationship of the different environmental phenomena, both terms (nT-CIE and T-OAE) are commonly used interchangeable. [...]".

Source: Springer Nature
Authors: Wolfgang Ruebsam & Lorenz Schwark 
DOI: https://doi.org/10.1007/s00531-024-02408-8

Read the full article here.

Abstract.

"Anthropogenic warming and nutrient over-enrichment of our oceans have resulted in significant, and often catastrophic, reductions in dissolved oxygen (deoxygenation). Stress on water-breathing animals from this deoxygenation has been shown to occur at all levels of biological organization: cellular; organ; individual; species; population; community; and ecosystem. Most climate forecasts predict increases in ocean deoxygenation, thus it is essential to develop reliable biological indicators of oxygen stress that can be used by regional and global oxygen monitoring efforts to detect and assess the impacts of deoxygenation on ocean life. [...]".

Source: EGUsphere 
Authors: Michael R. Roman et al.
DOI: https://doi.org/10.5194/egusphere-2024-616

Read the full article here.

Abstract.

"A prominent ocean region exhibiting depleted oxygen concentration is the northern Indian Ocean, whose projected deoxygenation trend in response to climate change requires a comprehensive understanding of the roles of ocean dynamics. We present newly compiled in situ data across platforms (e.g. cruises, Argo, buoy) in the Indonesian coasts of Sumatra and Java between 2010–2022. Combined with reanalysis products, our data detect oxygen-depleted waters attributed to the eastward advection of the northern Indian Ocean waters and monsoon-driven coastal upwelling. [...]".

Source: EGUsphere
Authors: Faisal Hamzah et al.
DOI: https://doi.org/10.5194/egusphere-2024-451

Read the full article here.

Abstract.

"Hydrogen sulfide is produced by heterotrophic bacteria in anoxic waters and via carbonyl sulfide hydrolysis and phytoplankton emissions under oxic conditions. Apparent losses of dissolved cadmium (dCd) and zinc (dZn) in oxygen minimum zones (OMZs) of the Atlantic and Pacific Oceans have been attributed to metal-sulfide precipitation formed via dissimilatory sulfate reduction. It has also been argued that such a removal process could be a globally important sink for dCd and dZn. However, our studies from the North Pacific OMZ show that dissolved and particulate sulfide concentrations are insufficient to support the removal of dCd via precipitation. [...]".

Source: Wiley Online Library
Authors: Nicole Buckley et al.
DOI: https://doi.org/10.1029/2023GB007881

Read the full article here.

Abstract.

"The potential impact of manganese mining on benthic remineralization in the Pacific Ocean was assessed in this study. We estimated total sediment oxygen uptake rates (TOU) using in situ autonomous benthic chambers at the polymetallic nodule and Co-rich polymetallic crust mining sites of Korea: at the Clarion-Clipperton Fracture Zone (PILOT site) in the eastern Pacific and the open-sea seamounts (OSM) 9-1 and OSM17 in the western Pacific, respectively. [...]".

Source: Science Direct
Authors: Sung-Uk An et al.
DOI: https://doi.org/10.1016/j.dsr.2024.104295

Read the full article here.

Abstract.

"Expansion of oceanic anoxia is a prevailing hypothesis for driving the marine end-Permian mass extinction and is mainly based on isotopic geochemical proxies. However, long-term oceanic redox conditions before the end-Permian mass extinction remain unresolved. Here we report a secular redox trend based on rock magnetic experiments and cerium anomalies through the Changhsingian and across the Permian-Triassic boundary at the Meishan section, China. Magnetic mineral assemblages changed dramatically at ca. 252.8 million years age (Ma), which indicates that oceanic deoxygenation started about 0.9 million years earlier than the end-Permian mass extinction. [...]".

Source: Nature
Authors: Min Zhang et al.
DOI: https://doi.org/10.1038/s43247-024-01394-8

Read the full article here.

Abstract.

"Oxygen minimum zones (OMZs) in the ocean are areas with dissolved oxygen (DO) concentrations below critical thresholds that impact marine ecosystems and biogeochemical cycling. In the northern Indian Ocean (NIO), OMZs exhibit a tendency to expand in mesopelagic waters and contribute significantly to global nitrogen loss and climate change. However, the microbial drivers of OMZ expansion in the NIO remain understudied. [...]".

Source: Frontiers in Marine Science
Authors: Jinyan Liu et al.
DOI: https://doi.org/10.3389/fmars.2024.1396306

Read the full article here.

Abstract.

"The physiological tolerances of marine species toward ambient temperature and oxygen can jointly be evaluated in a single metric: the metabolic index. Changes therein characterize a changing aerobic habitat tailored to species-specific thermal and hypoxia sensitivity traits. If the geographical limits of marine species as indicated by critical thresholds of the metabolic index shift abruptly in response to ocean warming and deoxygenation, aerobic habitat could potentially be lost abruptly. [...]".

Source: Wiley Online Library
Authors: Friederike Fröb et al.
DOI: https://doi.org/10.1029/2023EF004141

Read the full article here.

Abstract.

"Ongoing ocean deoxygenation is threatening marine organisms globally. In eastern boundary upwelling systems, planktonic copepods dominate the epipelagic zooplankton, being crucial in the marine food web. Yet, they must cope with severe hypoxia caused by shoaling of the oxygen minimum zone. Based on laboratory experiments during 2021, we found differential responses in the metabolic rate (MR) and critical oxygen partial pressure of three abundant copepods. Calanoides patagoniensis doubled its MR during the upwelling season, so better exploiting the spring phytoplankton bloom for feeding and reproduction while maintaining their critical oxygen partial pressure unchanged between seasons. [...]".

Source: Wiley Online Library
Authors: Leissing Frederick et al.
DOI: https://doi.org/10.1002/lno.12556

Read the full article here.

Abstract.

"The mitigation of climate change and pollution-related hypoxia and anoxia is a growing challenge for coastal communities. Known ocean conservation measures do not show the desired fast results counteracting deoxygenation. The new infrastructure related to the coastal production of renewable energies linked to the production of green hydrogen can provide new possibilities of artificial ocean reoxygenation to mitigate coastal hypoxia, but has to be treated urgently and seriously from different scientific, engineering and socio-economic angles. [...]".

Source: Wiley Online Library
Authors: Patricia Handmann & Douglas Wallace
DOI: https://doi.org/10.1111/gcb.17228

Read the full article here.

Abstract.

"Oxygen (O2) availability is essential for healthy coral reef functioning, yet how continued loss of dissolved O2 via ocean deoxygenation impacts performance of reef building corals remains unclear. Here, we examine how intra-colony spatial geometry of important Great Barrier Reef (GBR) coral species Acropora may influence variation in hypoxic thresholds for upregulation, to better understand capacity to tolerate future reductions in O2 availability. We first evaluate the application of more streamlined models used to parameterise Hypoxia Response Curve data, models that have been used historically to identify variable oxyregulatory capacity. [...]".

Source: Wiley Online Library
Authors: Nicole J. Dilernia et al.
DOI: https://doi.org/10.1002/ece3.11100

Read the full article here.

Abstract.

"Quantification of oxygen uptake at the ocean surface and its surface-to-interior pathways is crucial for understanding oxygen concentration change in a warming ocean. We investigate the mean meridional global oxygen transport between 1950 and 2009 using coupled physical-biogeochemical model output. We introduce a streamfunction in latitude-oxygen coordinates to reduce complexity in the description of the mean meridional oxygen pathways. [...]".

Source: Wiley Online Library
Authors: Esther Portela et al.
DOI: https://doi.org/10.1029/2023JC020259

Read the full article here.

"The satellite event 'New approaches to combat eutrophication and hypoxia' brought together partners under the GEF-8 Clean and Healthy Ocean Integrated Program (CHO-IP) for introductions and to begin the next phase of tackling eutrophication and hypoxia in 14 national child projects.

Representatives of partner organisations, the Food and Agriculture Organization of the United Nations (FAO), Asian Development Bank (ADB), Development Bank for Latin America (CAF), European Bank for Reconstruction and Development (EBRD), together with the  IOC-UNESCO Global Ocean Oxygen Network (GO₂NE) and the Global Water Partnership (GWP) discussed the program aims and objectives over the course of a 90 minute deoxygenation primer, panel discussion and Q&A session.

Keys points expressed by participants included that:

• Partners across scales and sectors must be involved early, with appropriate financing mechanisms, and engaged throughout to foster project ownership and outcome longevity.
• Scientific data, and methods of access, must be shared openly.
• Science will be unheeded unless it is delivered in a manner that is clear, timely, intelligible, and contextualised and translated to those who have, or will have, the capacity to use it.
• Collaboration with regional actors must be enhanced to aid identification of the most effective science-based actions that will have the highest impact in regional contexts, rather than following global trends.
• International institutions must be encouraged to identify and engage with initiatives of actors in their networks that may already be addressing or adapting to hypoxic conditions.
• Scientifically well-versed personnel are needed in Development Banks and other institutions positioned to leverage existing networks to tackle deoxygenation and other marine issues.

Partners will now move ahead with the program's Global Coordination Project and begin to make connections to national actors and networks working to address eutrophication and hypoxia and implement the program in the 14 participating countries.

The program will synergise with the Global Ocean Oxygen Database and Atlas (GO₂DAT), an endorsed action under the UN Ocean Decade of Ocean Science for Sustainable Development and may lead to the development of new Actions as the program is implemented."

Contact: go2ne-secretariat@unesco.org

More information:

The 'New approaches to combat eutrophication and hypoxia' event

The GEF Clean and Healthy Ocean Program

IOC-UNESCO program announcement

Abstract.

"In the tropical Pacific, weak ventilation and intense microbial respiration at depth give rise to a low dissolved oxygen (O2) environment that is thought to be ventilated primarily by the equatorial current system (ECS). The role of mesoscale eddies and vertical mixing as potential pathways of O2 supply in this region, however, remains poorly known due to sparse observations and coarse model resolution. Using an eddy resolving simulation of ocean circulation and biogeochemistry, we assess the contribution of these processes to the O2 budget balance and find that vertical mixing of O2 [...]".

Source: Wiley Online Library
Authors: Yassir A. Eddebbar et al.
DOI: https://doi.org/10.1029/2023JC020588

Read the full article here.

Abstract.

"The largest continental shelf Oxygen Minimum Zone (OMZ) in the world is formed along the Indian western shelf in the eastern Arabian Sea during the Southwest Monsoon [(SWM); June–September], which is a natural pollution event associated with the coastal upwelling. This study examines the composition, abundance, and distribution of copepods during the Northeast Monsoon [(NEM); November to February] and SWM in 50 m depth zones along the Indian western shelf in the eastern Arabian Sea. [...]".

Source: Science Direct
Authors: Vidhya Vijayasenan et al.
DOI: https://doi.org/10.1016/j.marenvres.2024.106380

Read the full article here.

Abstract.

"Hypoxic zones and oceanic deoxygenation are spreading worldwide due to anthropogenic activities and climate change, greatly affecting marine organisms exposed to lowered O2. Yet, the effects of the lowered O2 on phytoplankton are often neglected when studying O2 effects as they are the O2 producers. Here we showed that low O2 (dissolved O2, 150 ± 10 μmol L−1) enhanced the growth of the marine diatom Thalassiosira pseudonana in limited light but reduced it in moderate to inhibitory light and that hypoxia (40 ± 7.5 μmol L−1) reduced its growth at any growth lights. [...]".

Source: Science Direct
Authors: Bokun Chen et al.
DOI: https://doi.org/10.1016/j.envexpbot.2024.105667

Read the full article here.

In-person satellite event "New approaches to combat eutrophication and hypoxia" 

April 9th, 17:00 – 20:00 CEST at Tech Barcelona, Pier 07, Barcelona

"The event takes place before the opening day of the United Nations 2024 Ocean Decade Conference on the 10-12 April.

This joint event presents new approaches to combat hypoxia and eutrophication through the GEF-8 Clean and Healthy Ocean Integrated Program (CHO-IP) and facilitates connections for co-designed action.
Following the event, attendees and speakers can exchange views over refreshments.

A programme is attached. Attendance does not require registration to the Ocean Decade Conference, but separate registration to this event specifically is required. You can register by clicking below.

Please note that no travel support is offered to attend this event."

You can register for the event here. 

You can find the programme here. 

Abstract.

"Reef fishes in the California Current Ecosystem have evolved in habitats affected by seasonally variable, episodic upwelling of high pCO2 (acidified, low pH) and low dissolved oxygen (deoxygenated) water, which suggests that these fishes might exhibit resilience to ocean acidification (OA) and deoxygenation. Yet, how the fitness of these fish are affected by natural variability in pH and DO over short time scales remains poorly understood, as do the effects of longer-term trends in pH and DO driven by climate change. [...]".

Source: Science Direct
Authors: Corianna Flannery & Eric P. Bjorkstedt
DOI: https://doi.org/10.1016/j.jembe.2024.151993

Read the full article here.

GO₂NE Webinar on Ocean Deoxygenation. 

"Do you want to know more about deoxygenation in the ocean?
Join us for the upcoming webinar!

Wednesday, 3rd April 2024, 14:00 h – 15:00 CEST

Registration link

Please join the Global Ocean Oxygen Network (IOC Expert Working Group GO2NE) for a new session of its webinar series on ocean deoxygenation. The 28th webinar will take place 3 April 2024, 14:00 h CEST. The webinar will feature presentations by a more senior and an early-career scientist, 20 minutes each, followed by 10-minute moderated discussion sessions. 

If you are interested to present at one of the upcoming webinars please submit a short abstract here.

Moderation: 
Aileen Tan Shau Hwai
Centre For Marine & Coastal Studies, Unversiti Sains Malaysia, Malaysia

Speakers:
Tom Hull
Centre for Environment Fisheries and Aquaculture Science (CEFAS), United Kingdom
"Observing ocean oxygen in UK shelf seas"

Monaliza Mohd-Din
Marine Science Program, Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Malaysia
"High biomass diatom blooms induced the formation of hypoxic-anoxic zones in the inner part of Johor Strait"

If you want to receive further information about upcoming webinars, please register here." 

Abstract.

"Ocean acidification and deoxygenation co-occur in marine environments, causing deterioration of marine ecosystems. However, effects of compound stresses on marine organisms and their physiological coping mechanisms are largely unknown. Here, we show how high pCO2 and low dissolved oxygen (DO) cause transcriptomic changes in eggs of a demersal fish (Sillago japonica), which are fully exposed to such stresses in natural environment. Overall gene expression was affected more strongly by low DO than by high pCO2. Enrichment analysis detected significant stress responses such as glycolytic processes in response to low DO. [...]".

Source: Science Direct
Authors: Akira Iguchi et al.
DOI: https://doi.org/10.1016/j.scitotenv.2023.169484

Read the full article here.

Abstract.

"Abrupt changes in ocean biogeochemical variables occur as a result of human-induced climate forcing as well as those which are more gradual and occur over longer timescales. These abrupt changes have not yet been identified and quantified to the same extent as the more gradual ones. We review and synthesise abrupt changes in ocean biogeochemistry under human-induced climatic forcing. We specifically address the ocean carbon and oxygen cycles because the related processes of acidification and deoxygenation provide important ecosystem hazards. [...]".

Source: Biogeosciences
Authors: Christoph Heinze et al.
DOI: https://doi.org/10.5194/bg-2023-182

Read the full article here.

Full title: "Marine anoxia initiates giant sulfur-oxidizing bacterial mat proliferation and associated changes in benthic nitrogen, sulfur, and iron cycling in the Santa Barbara Basin, California Borderland"

Abstract.

"The Santa Barbara Basin naturally experiences transient deoxygenation due to its unique geological setting in the southern California Borderland and seasonal changes in ocean currents. Long-term measurements of the basin showed that anoxic events and subsequent nitrate exhaustion in the bottom waters have been occurring more frequently [...]".

Source: Biogeosciences
Authors: David J. Yousavich et al.
DOI: https://doi.org/10.5194/bg-21-789-2024

Read the full article here.

Abstract.

"Accelerated Arctic warming has raised concerns about future environmental conditions in the Bering Sea, one of the world's most productive marine ecosystems. Marine Isotope Stage (MIS) 11 (424–374 ka), a period with orbital parameters similar to those of the current interglacial (Holocene), is thought to be a suitable analog to predict future marine environments. Here, we reconstruct paleoredox changes in the Bering Sea over the last 800 kyr using high-resolution U/Th ratios from four sites, which were sampled by the Integrated Ocean Drilling Program (IODP) Expedition 323. [...]".

Source: Science Direct
Authors: Xuguang Feng et al.
DOI: https://doi.org/10.1016/j.palaeo.2023.111982

Read the full article here.

Abstract.

"The ocean enabled the diversification of life on Earth by adding O2 to the atmosphere, yet marine species remain most subject to O2 limitation. Human industrialization is intensifying the aerobic challenges to marine ecosystems by depleting the ocean's O2 inventory through the global addition of heat and local addition of nutrients. Historical observations reveal an ∼2% decline in upper-ocean O2 and accelerating reports of coastal mass mortality events. The dynamic balance of O2 supply and demand provides a unifying framework for understanding these phenomena across scales from the global ocean to individual organisms. [...]".

Source: Annual Review of Marine Science
Authors: Curtis Deutsch et al.
DOI: https://doi.org/10.1146/annurev-marine-040323-095231

Read the full article here.

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.

Full title: "Highly active fish in low oxygen environments: vertical movements and behavioural responses of bigeye and yellowfin tunas to oxygen minimum zones in the eastern Pacific Ocean"

Abstract.

"Oxygen minimum zones in the open ocean are predicted to significantly increase in volume over the coming decades as a result of anthropogenic climatic warming. The resulting reduction in dissolved oxygen (DO) in the pelagic realm is likely to have detrimental impacts on water-breathing organisms, particularly those with higher metabolic rates, such as billfish, tunas, and sharks. [...]".

Source: Springer Nature 
Authors: Nicolas E. Humphries et al.
DOI: https://doi.org/10.1007/s00227-023-04366-2

Read the full article here.

Abstract.

"Ocean deoxygenation is intensifying globally due to human activities – and is emerging as a grave threat to coral reef ecosystems where it can cause coral bleaching and mass mortality. However, deoxygenation is one of many threats to coral reefs, making it essential to understand how prior environmental stress may influence responses to deoxygenation. To address this question, we examined responses of the coral holobiont (i.e., the coral host, Symbiodiniaceae, and the microbiome) to deoxygenation in corals with different environmental stress backgrounds. [...]".

Source: Frontiers in Marine Science
Authors: Sara D. Swaminathan et al.
DOI: https://doi.org/10.3389/fmars.2023.1301474

Read the full article here.

Abstract.

"Global warming and anthropogenic activity are boosting marine deoxygenation in many regions around the globe. Deoxygenation is a critical ocean stressor with profound implications for marine ecosystems and biogeochemical cycles. Understanding the dynamics and evolution of past deoxygenation events can enhance our knowledge of present-day and future impacts of climate change and anthropogenic pressure on marine environments. Many studies have reconstructed the evolution redox conditions of past deoxygenation events using geochemical proxies. [...]".

Source: Science Direct
Authors: Ricardo D. Monedero-Contreras et al.
DOI: https://doi.org/10.1016/j.palaeo.2023.111953

Read the full article here.

Abstract.

"Despite the observation that we are witnessing a true oxygen crisis, the ocean deoxygenation theme is getting less attention from the media and population compared to other environmental stressors concerning climate change. The current ocean oxygen crisis is characterized by a complex interplay of climatic, biological, and oceanographic processes acting at different time scales. Earth system models offer insights into future deoxygenation events and their potential extent [...]".

Source: Science Direct
Authors: Alan Maria Mancini et al.
DOI: https://doi.org/10.1016/j.earscirev.2023.104664

Read the full article here.

Full title: "The early Toarcian Oceanic Anoxic Event (Jenkyns Event) in the Alpine-Mediterranean Tethys, north African margin, and north European epicontinental seaway"

Abstract.

"The early Toarcian Oceanic Anoxic Event (Jenkyns Event) was associated with major world-wide climatic changes with profound effects on the global carbon cycle. This review revisits the available literature covering the Jenkyns Event applying an updated common stratigraphic definition, allowing illustration of the development and evolution of anoxia in the Alpine-Mediterranean Tethys [...]".

Source: Science Direct 
Authors: Gabriele Gambacorta et al.
DOI: https://doi.org/10.1016/j.earscirev.2023.104636

Read the full article here.

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.

Abstract.

"The discoveries of large reefs within cold-water coral mound provinces revealed that the West African margin is a coral hotspot area in the Atlantic Ocean. The most striking observation is that cold-water corals thrive in extensive oxygen minimum zones under extreme conditions. This points to a wide tolerance of cold-water corals in these regions to low oxygen concentrations. The coral mound provinces off Mauritania, Angola, and Namibia, which are located in the centre of the local oxygen minimum zones, were selected as key study areas, and their regional oceanographic, bio-ecological, and geo-morphological settings are described in detail. [...]".

Source: Springer Nature
Authors: Claudia Wienberg et al.
DOI: https://doi.org/10.1007/978-3-031-40897-7_8

Read the full article here.

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.

GO₂NE Webinar on Ocean Deoxygenation. 

"Do you want to know more about deoxygenation in the ocean?
Join us for the upcoming webinar!

Monday, 21st February 2024, 14:00 h – 15:00 CET

Registration link

Please join the Global Ocean Oxygen Network (IOC Expert Working Group GO2NE) for a new session of its webinar series on ocean deoxygenation. The 27th webinar will take place 21 February 2024, 14:00 h CET. The webinar will feature presentations by a more senior and an early-career scientist, 20 minutes each followed by 10 minutes moderated discussion sessions. 

If you are interested to present at one of the upcoming webinars please submit a short abstract here.

Moderation: 
Natalya Gallo
University of Bergen and Bjerknes Centre for Climate Research, Norway

Speakers:
Martine Røysted Solås
University of Bergen and Bjerknes Centre for Climate Research, Norway
"Vertical distribution of mesopelagic scattering layers under different oxygen conditions: Insights from a western Norwegian fjord"

Carl Reddin
GeoZentrum Nordbayern, Germany - Paleobiology, and Integrative Ecophysiology at AWI, Germany
"Warming-associated deoxygenation as a driver of marine extinction? The deep past and near future"

If you want to receive further information about upcoming webinars please register here." 

PhD position at the Ludwig-Maximilians-Universität München

"The Department of Earth and Environmental Sciences at LMU Munich invites applications for one PhD position in Geomicrobiology/ Environmental Microbiology to experimentally investigate the diversity and activity of marine microbial communities in the context of ocean deoxygenation.

Together with warming and acidification, ocean deoxygenation is considered one of the three major impacts of climate change in global oceans according to IPCC, and a main research scientific topic for organizations such as UNESCO or IUCN. In the DFG Emmy-Noether Research Group in Biogeochemistry and Climate Change, we investigate the effects of ocean deoxygenation on dissolved organic matter (DOM) sequestration, due to interactions with microbial communities and the marine carbon and sulfur cycles. By combining field work experiments with state-of-art laboratory techniques from different disciplines, we aim to decipher new links between microbes and DOM, in the context of a changing, deoxygenated ocean."

You can find more details here. 

The 4th Issue of GOOD News is now available here. 

Previous issues are available in the archive here.

Abstract.

"Ocean deoxygenation and expansion and intensification of hypoxia in the ocean are a major, growing threat to marine ecosystems. Measures currently used to protect marine biodiversity (e.g., marine protected areas) are ineffective in countering this threat. Here, we highlight the example of the Gulf of St. Lawrence in eastern Canada, where oxygen loss is not only due to eutrophication (which can be mitigated by nutrient controls) but also is a consequence of ocean circulation change and warming. Climate-related loss of oxygen will be an increasingly widespread source of risk to marine biodiversity over this century. [...]".

Source: Springer Nature
Authors: Douglas W. R. Wallace et al.
DOI: https://doi.org/10.1007/s11027-023-10094-1

Read the full article here.

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.

Abstract.

"Ocean deoxygenation is a key stressor for marine ecosystems and biogeochemical cycles (Gruber, 2011; Breitburg et al., 2018). Climate projections based on Earth system models (ESMs) suggest that the global oxygen inventory will undergo a significant decline over the next century under persistent greenhouse gas emissions (Bopp et al., 2013; Kwiatkowski et al., 2020). Oxygen minimum zones (OMZs) located close to productive eastern boundary upwelling systems (EBUSs) and the Arabian Sea may expand or shift in spatial extent dramatically, thereby impacting regional marine habitats (Stramma et al., 2012) and ecosystem services (Lachkar et al., 2023). [...]".

Source: Frontiers in Marine Science
Authors: Masahito Shigemitsu et al.
DOI: https://doi.org/10.3389/fmars.2023.1355015

Read the full article here.

Abstract.

"During the Messinian, the sensitivity of the Mediterranean Basin to ecosystem perturbation was enhanced in response to the progressive restriction of water exchange with the Atlantic Ocean. The widespread deposition of organic-rich layers (i.e. sapropel) during the Messinian testifies the perturbation of the carbon and oxygen cycles; indeed, these sediments were deposited under conditions of oxygen starvation, presumably in response to a periodic deterioration of the thermohaline circulation strength. [...]".

Source: Science Direct 
Authors: Alan Maria Mancini et al.
DOI: https://doi.org/10.1016/j.dsr.2023.104217

Read the full article here.

Abstract.

"Ocean warming is associated with a decline in the global oxygen (O₂) inventory, but the ratio of O₂ loss to heat gain is poorly understood. We analyzed historical variability in temperature (T), O₂, and nitrate (N⁢O3−) in hydrographic observations and model simulations of the North Atlantic, a relatively well-sampled region that is important for deep ocean ventilation. Multidecadal fluctuations of O₂ concentrations in subpolar thermocline waters (100–700 m) are correlated with changes in their heat content, with a slope 35% steeper than that expected from thermal solubility. [...]".

Source: Wiley Online Library
Authors: Andrew J. Margolskee et al.
DOI: https://doi.org/10.1029/2023GB007930

Read the full article here.

Full title: "Sedimentary environment and benthic oxygenation history of the Upper Cretaceous Austin Chalk Group, south Texas: An integrated ichnological, sedimentological and geochemical approach"

Abstract.

"Oxygen concentration in the ocean is vital for sustaining marine ecosystems. While the potential impacts of deoxygenation on modern oceans are hard to predict, lessons can be learned from better characterizing past geological intervals formed under a greenhouse climate. The greenhouse Cretaceous containing several oceanic anoxic events [...]".

Source: Wiley Online Library
Authors: Charlie Y. C. Zheng et al. 
DOI: https://doi.org/10.1111/sed.13169

Read the full article here.

GO₂NE Webinar on Ocean Deoxygenation. 

"Do you want to know more about deoxygenation in the ocean?
Join us for the upcoming webinar!

Monday, 29th January 2024, 10:00 h – 11:00 CET

Registration link

Please join the Global Ocean Oxygen Network (IOC Expert Working Group GO2NE) for a new session of its webinar series on ocean deoxygenation. The 26th webinar will take place 29 January 2024, 10:00 h CET. The webinar will feature presentations by a more senior and an early-career scientist, 20 minutes each followed by 10 minutes moderated discussion sessions. 

If you are interested to present at one of the upcoming webinars please submit a short abstract here.

Moderation: 
Minhan Dai
Xiamen University, China

Speakers:
Yawei Shen
Xiamen University, China
"Will it be possible to shape the hypoxia tolerance of marine animals? A case study in aquaculture abalone"

Folco Giomi
Independent researcher, Italy
"Marine life on stage. A focus on oxygen availability to the scale of relevant players"

If you want to receive further information about upcoming webinars please register here." 

Abstract.

"In the ocean, downward flux of particles produced in sunlit surface waters is the major component of the biological carbon pump, which sequesters atmospheric carbon dioxide and fuels deep-sea ecosystems. The efficiency of downward carbon transfer is expected to be particularly high in tropical upwelling systems where hypoxia occurring beneath the productive surface waters is thought to hamper particle consumption. However, observations of both particle feeders and carbon export in low-oxygen waters are scarce. Here, we provide evidence that hypoxia-tolerant zooplankton feed on sinking particles in the extensive Oxygen Minimum Zone (OMZ) off Peru. [...]".

Source: Nature
Authors: Anja Engel et al. 
DOI: https://doi.org/10.1038/s43247-023-01140-6

Read the full article here.

Abstract.

"Fossils from the Araripe Basin (northeastern Brazil) are known for their remarkable preservation of vertebrates and invertebrates, even including soft tissues. They occur in carbonate concretions within organic carbon-rich strata assigned to the Romualdo Formation. Here we present integrated stable isotope, elemental and microfossil records from the Sítio Sobradinho outcrop, Araripe Basin, northeastern Brazil. Our results imply that black shales hosting fossil-bearing carbonate concretions within the lower Romualdo Formation were deposited during Oceanic Anoxic Event (OAE) 1b (Kilian sub-event). [...]".

Source: Wiley Online Library
Authors: Marlone H. H. Bom et al.
DOI: https://doi.org/10.1029/2023PA004736

Read the full article here.

Abstract.

"Climate warming likely drives ocean deoxygenation, but models still cannot fully explain observed declines in oxygen. One unconstrained parameter is the oxygen demand per carbon respired for complete remineralization of organic matter (i.e., the total respiration quotient, rΣ-O2:C). Here, we tested if rΣ-O2:C declined with depth by quantifying suspended concentrations of particulate organic carbon (POC), particulate organic nitrogen (PON), particulate organic phosphorus (POP), particulate chemical oxygen demand (PCOD), and total oxygen demand (Σ-O2 = PCOD + 2PON) down to a depth of 1,000 m in the Sargasso Sea. [...]".

Source: Wiley Online Library
Authors: Skylar D. Gerace et al. 
DOI: https://doi.org/10.1029/2023GB007814

Read the full article here.

Abstract.

"A geochemical study of an ancient mass-extinction event shows that only moderate expansion of oxygen-deficient waters along continental margins is needed to decimate marine biodiversity. This finding provides a stark warning of the possible consequences of human-driven ocean deoxygenation on life in Earth’s shallow oceans. [...]".

Source: Nature
Authors: Brian Kendall
DOI: https://doi.org/10.1038/s41561-023-01310-3

Read the full article here.

Abstract.

"Marine environments wherein long-term microbial oxygen consumption exceeds oxygen replenishment can be associated with oxygen minimum zones (OMZ). The Bay of Bengal OMZ (BOB-OMZ) is one of the most intense OMZs globally. To assess the contribution of bacterial oxygen consumption to oxygen loss in BOB-OMZ, we measured bacterial production (BP), temperature, salinity, and dissolved oxygen (DO) in the whole water column. [...]".

Source: Frontiers in Microbiology
Authors: Wenqi Ye et al.
DOI: https://doi.org/10.3389/fmicb.2023.1250575

Read the full article here.

Abstract.

"The development of widespread marine anoxic and/or euxinic conditions has been proposed as a likely driver of the mid-Capitanian mass extinction. However, the driving mechanisms and spatiotemporal evolution of anoxia/euxinia remain poorly constrained. In order to decipher changes in marine redox conditions and their possible influence on the mid-Capitanian biotic crisis, we applied multiple geochemical indicators to three sections across a shelf-to-basin transect in the Middle Permian Kuhfeng and Lower Yinping formations of the Lower Yangtze Basin, South China. [...]".

Source: Science Direct 
Authors: Bolin Zhang et al.
DOI: https://doi.org/10.1016/j.gloplacha.2023.104273

Read the full article here.

Abstract.

"Marine redox conditions (that is, oxygen levels) impact a wide array of biogeochemical cycles, but the main controls of marine redox since the start of the Phanerozoic about 538 million years ago are not well established. Here we combine supervised machine learning with shale-hosted trace metal concentrations to reconstruct a near-continuous record of redox conditions in major marine depositional settings. We find synchronously opposite redox changes in upper ocean versus deep shelf and (semi-)restricted basin settings ('redox anticouples', nomen novum) in several multi-million-year intervals, which can be used to track the positions of oxygen-minimum zones and the primary locations of organic burial through time. [...]".

Source: Nature
Authors: Xiangli Wang et al. 
DOI: https://doi.org/10.1038/s41561-023-01296-y

Read the full article here.

Abstract.

"The Indian Ocean Dipole (IOD) plays a crucial role in shaping local and global environments, yet its effects on interannual variability of the Arabian Sea oxygen minimum zone (ASOMZ) remains poorly understood. Here, we used a coupled physical-biogeochemical model to investigate the dynamical response of the ASOMZ to extreme negative (2016) and positive (2019) IOD events. Our findings revealed that the suboxic area of the ASOMZ reduced (expanded) by ∼27% (∼28%) after the negative (positive) IOD event. [...]".

Source: Wiley Online Library
Authors: Zhiwei Zhang et al.
DOI: https://doi.org/10.1029/2023GL104226

Read the full article here.

Abstract.

"The Arabian Sea hosts a perennial and intense oxygen minimum zone (OMZ) at 150–1200 m depths with O2 concentrations <0.5 ml/l. It is generally believed that the oxygen-depleted conditions at mid-water depths result from high rate of O2 consumption due to monsoon-driven productivity generating a high organic matter flux, combined with slow renewal of thermocline waters in the region. With global warming and increasing hypoxia, there is growing interest to better understand the various factors controlling oxygen conditions in the thermocline waters and the impact on the nutrient cycling and climate. [...]".

Source: Science Direct 
Authors: Arun Deo Singh et al.
DOI: https://doi.org/10.1016/j.eve.2023.100028

Read the full article here.

Global Ocean Oxygen Network on World Ocean Day 2024

"In 2024, the Global Ocean Oxygen Network (GO2NE), an IOC-UNESCO working group under the United Nations Decade of Ocean Science for Sustainable Development, is again planning to mark World Ocean Day (WOD) on June 8th by working together with institutions to hold a series of in-person and virtual outreach activities. Just as last year, the GO2NE reaching out to identify suitable institutions where these activities could take place, with the aim of supporting the delivery of informative events to advance knowledge on the risks and impacts of deoxygenation in the marine environment.

In 2023, partners across the globe organised in-person, interactive, and virtual science communication events. GO2NE hopes to further promote more events that may already be in the planning stages and to create opportunities to integrate ocean oxygen in planned and new outreach activities.

If you are already involved in a WOD event this year or know of a planned WOD event near you, please let us know. Suggestions of organisations who may be interested to host an event or integrate ocean oxygen in their event, as well as suggestions for potential expert participation in activities around the Day, are very welcome. The short form linked at the end of this page has been created to collect your suggestions and inputs. Your time is very much appreciated!

The GO2NE Secretariat looks forward to supporting the coordination and organisation of efforts to raise awareness of ocean deoxygenation around World Ocean Day and to share opportunities to engage in the hosting and attendance of events."

https://forms.gle/TPMrSVwK8e1EN1fV6

Abstract.

"The tectonic closure of the Central American Seaway (CAS) during the mid-Miocene to mid-Pliocene (∼16–3 Ma BP) is thought of as a key interval for the onset of the present-day tropical Pacific oxygen minimum zone (OMZ). In this study we investigate the impact of an open CAS on the ocean circulation and the OMZ in the tropical Pacific. We perform a series of sensitivity experiments with the Kiel Climate Model, where we vary the CAS sill depth from shallow to deep. [...]".

Source: Wiley Online Library
Authors: Vyacheslav Khon et al. 
DOI: https://doi.org/10.1029/2023GL103728

Read the full article here.

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.

GO₂NE Webinar on Ocean Deoxygenation. 

"Do you want to know more about deoxygenation in the ocean?
Join us for the upcoming webinar!

Monday, 18th December 2023, 16:00 h – 17:00 CET

Registration link

Please join the Global Ocean Oxygen Network (IOC Expert Working Group GO2NE) for a new session of its webinar series on ocean deoxygenation. The 25th webinar will take place 18 December 2023, 16:00 h CET. The webinar will feature presentations by a more senior and an early-career scientist, 20 minutes each followed by 10 minutes moderated discussion sessions. 

If you are interested to present at one of the upcoming webinars please submit a short abstract here.

Moderation: 
Caroline Slomp
Radboud University / Utrecht University

Speakers:
Darci Rush
Royal NIOZ, The Netherlands
"Tracing past marine anoxia using lipid biomarkers"

Jannes Koelling
University of Washington, USA
"On the decadal variability of oxygen uptake, export, and storage in the Labrador Sea"

If you want to receive further information about upcoming webinars please register here." 

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.

Abstract.

"This study provides a detailed examination of a condensed Cenomanian-Turonian (C-T) succession of two sections (Dokan Dam and Khalakan) in the Kurdistan Region, Northeastern Iraq, based on biostratigraphy (calcareous nannofossils and planktic foraminifera), carbon and oxygen isotope geochemistry, and facies analysis. The C/T boundary in this region is characterized by a hiatus noticeable due to the absence of the Globigerinelloides benthonensis and Dicarinella hagni subzones and the lack of positive carbon isotope excursion (CIE) peak b during the Oceanic Anoxic Event 2 (OAE2). [...]".

Source: Science Direct
Authors: Fadhil A. Lawa et al.
DOI: https://doi.org/10.1016/j.jafrearsci.2023.105064

Read the full article here.

Abstract.

"The uptake of dissolved oxygen from the atmosphere via air-sea gas exchange and its physical transport away from the region of uptake are crucial for supplying oxygen to the deep ocean. This process takes place in a few key regions that feature intense oxygen uptake, deep water formation, and physical oxygen export. In this study we analyze one such region, the Labrador Sea, utilizing the World Ocean Database (WOD) to construct a 65–year oxygen content time series in the Labrador Sea Water (LSW) layer (0–2200 m). [...]".

Source: Frontiers in Marine Science 
Authors: Jannes Koelling et al.
DOI: https://doi.org/10.3389/fmars.2023.1202299

Read the full article here.

PhD position at the ACCE (Adapting to the Challenges of a Changing Environment) at the University of York 

"Recent high-profile and extraordinary marine heatwaves (e.g. the Pacific “Blob”) have galvanised the scientific community to better understand climate-driven extreme events in the ocean and their potential ecosystem impacts. The North Sea is a global hot spot for marine heatwaves, with many marine species already exceeding their comfortable thermal range. Marine heatwaves can also significantly influence air temperature patterns over land, with warm sea temperatures having been identified as a main driver of the record-breaking UK summer heatwave of 2018."

You can find more details here.