黑料视频

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

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: Douglas W. R. Wallace et al.
DOI: 10.1007/s11027-023-10094-1

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

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鈦�O3鈭�) 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鈥�700 m) are correlated with changes in their heat content, with a slope 35% steeper than that expected from thermal solubility. [...]."

"The  webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment 鈥� ocean deoxygenation. Organised and hosted by , each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 18 December 2023 No 25

Moderator:

Radboud University / Utrecht University

Speakers:

Royal NIOZ, The Netherlands
"Tracing past marine anoxia using lipid biomarkers"

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

You can watch the GO₂NE Webinar 18 December 2023 No 25 recording . 

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

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 characterized by widespread oxygen-deficient water is ideal in this regard. The Austin Chalk Group in south Texas (USA) shows organic-rich intervals that can be linked to oxygen depletion in the ocean, but the exact bottom water oxygenation conditions have not been estimated. [...]." 

Source: European Marine Board

"On Thursday 7 December 2023, EMB hosted its 35th Third Thursday Science Webinar featuring Toste Tanhua who spoke 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' and EMB Position Paper No. 23 'Advancing Citizen Science for Coastal and Ocean Research'.

Toste Tanhua is a Senior Scientist at 黑料视频 (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 . 

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

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

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 S铆tio 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: Skylar D. Gerace et al. 
DOI: 10.1029/2023GB007814

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, r危-O2:C). Here, we tested if r危-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 (危-O2 = PCOD + 2PON) down to a depth of 1,000 m in the Sargasso Sea. [...]."

Source: Nature
Authors: Brian Kendall
DOI: 10.1038/s41561-023-01310-3

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鈥檚 shallow oceans. [...]."

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

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. [...]."

"The  webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment 鈥� ocean deoxygenation. Organised and hosted by , each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 20 November 2023 No 24

Moderator:

University of Bergen and Bjerknes Centre for Climate Research, Norway

Speakers:

NORCE Norwegian Research Centre, Norway
"On the Origins of Open Ocean Oxygen Minimum Zones"

Scripps Institution of Oceanography, University of California San Diego, USA
"Oxygen supply in the tropical Pacific: A role for turbulence and mesoscale eddies"

You can watch the GO₂NE Webinar 20 November 2023 No 24 recording .  

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

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

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: Wiley Online Library
Authors: Zhiwei Zhang et al.
DOI: 10.1029/2023GL104226

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 鈭�27% (鈭�28%) after the negative (positive) IOD event. [...]."

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

Abstract

"The Arabian Sea hosts a perennial and intense oxygen minimum zone (OMZ) at 150鈥�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: Wiley Online Library
Authors: Vyacheslav Khon et al. 
DOI: 10.1029/2023GL103728

Abstract

"The tectonic closure of the Central American Seaway (CAS) during the mid-Miocene to mid-Pliocene (鈭�16鈥�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: Frontiers in Marine Science
Authors: Sheng Huang et al.
DOI: 10.3389/fmars.2023.1291232

Abstract

"Oceanic dissolved oxygen (DO) decline in the Indian Ocean has profound implications for Earth鈥檚 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: Annie Bourbonnais et al.
DOI: 10.3389/fmars.2023.1333731

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鈥檚 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: IOC-UNESCO

"UNESCO鈥檚 Intergovernmental Oceanographic Commission (IOC/UNESCO), El Centro de Estudios Avanzados en Zonas 脕ridas (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."

For further information, please read . 

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

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

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), one of the most important aquaculture resources in Japan. Moreover, there is concern regarding the combined impacts of coastal warming, acidification, and deoxygenation on Pacific oysters. [...]."

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

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, 鈭�183 Ma). However, the detailed processes and mechanisms behind widespread ocean deoxygenation are unclear. [...]."

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

Abstract

"Atmospheric oxygen (O2) concentrations likely remained below modern levels until the Silurian鈥揇evonian, 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: Wiley Online Library
Authors: Ludovic Pascal et al.
DOI: 10.1111/gcb.16994

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

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

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

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鈥搚ear oxygen content time series in the Labrador Sea Water (LSW) layer (0鈥�2200 m). [...]."

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

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: Science Direct
Authors: Joseph T. Kulenguski et al.
DOI: 10.1016/j.palaeo.2023.111756

Abstract

"Oceanic anoxic events (OAEs) represent discrete intervals of decreased marine oxygen concentrations often associated with volcanism, enhanced organic carbon burial coupled with positive 未13C excursions, and significant biotic turnover. Cretaceous OAE 2 (ca. 94 Mya) is especially notable for globally-distributed changes in calcareous invertebrate and plankton populations. While the presence of organic-rich facies is consistent with locally anoxic environments in many cases, determining the global extent of anoxia is more problematic. [...]."

Source: Frontiers in Marine Science
Authors: Weiwei Fu & Tsuneo Ono
DOI: 10.3389/fmars.2023.1316092

Abstract

"The decline of oxygen levels in coastal waters has emerged as a significant and pressing concern, carrying extensive ecological and environmental ramifications. Coastal areas, the interface between land and sea, represent intricate and dynamic ecosystems that hold paramount importance for global biodiversity and sustain a multitude of human activities. Nevertheless, these coastal regions are confronted with mounting stressors originating from both human-induced factors such as nutrient pollution (Dai et al., 2023), natural forces like coastal modifications (Newton et al., 2016), and climate change forced by anthropogenic CO2 emission (Bindoff et al., 2019; IPCC, 2021). [...]."

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

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: Science Direct
Authors: Bolin Zhang et al.
DOI: 10.1016/j.gloplacha.2023.104273

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: Nature
Authors: Anders Lindskog et al.
DOI: 10.1038/s41561-023-01287-z

Abstract

"Marine biodiversity increased markedly during the Ordovician Period (~487鈥�443 million years ago). Some intervals within the Ordovician were associated with unusually rapid and prominent rises in taxonomic richness, the reasons for which remain debated. Links between increased oxygenation and biodiversification have been proposed, although supporting marine oxygen proxy data are limited. Here we present an expansive multi-site iodine-to-calcium (I/Ca) record from Lower鈥揗iddle Ordovician marine carbonates in Baltoscandia that provides a detailed account of the spatio-temporal development of oxygen conditions across this palaeoshelf. [...]."

Source: Nature
Authors: Huanye Wang et al.
DOI: 10.1038/s41561-023-01292-2

Abstract

"The Atlantic meridional overturning circulation (AMOC) exerts a major control on the global distribution of heat, dissolved oxygen and carbon in the ocean. Yet the timing and cause of the inception of this system and its evolution since the start of the Cenozoic Era 65 million years ago (Ma) remain highly uncertain. Here we present records of microbial source indicators based on glycerol dialkyl glycerol tetraether distributions from the Cenozoic Northwest Atlantic Ocean (~43鈥�18鈥塎a) and use them to infer changes in AMOC-driven deep-ocean oxygenation. [...]."

Source: Science Direct
Authors: Xintong Huang et al.
DOI: 10.1016/j.scitotenv.2023.164982

Abstract

"Ocean deoxygenation, acidification, and decreased phosphorus availability are predicted to increase in coastal ecosystems under future climate change. However, little is known regarding the combined effects of such environmental variables on the green tide macroalga Ulva prolifera. Here, we provide quantitative and mechanistic understanding of the acclimation mechanisms of U. prolifera to ocean deoxygenation, acidification, and phosphorus limitation under both laboratory and semi-natural (mesocosms) conditions. [...]."

Source: Current Journal
Authors: Kyla J. Kelly et al.
DOI: 10.5334/cjme.86

Abstract

"The University of Southern California鈥檚 (USC) Joint Educational Project鈥檚 STEM Education Programs hosted a three-day summer workshop focused on marine microbiology and coastal deoxygenation for high school educators. To increase ocean literacy in high school students from Title I schools, topical marine science research was translated into four lesson plans appropriate for classrooms that teach biology and environmental science. The lesson plans focus on how marine microbes affect and are affected by the dissolved oxygen content of seawater but covered diverse oceanography topics including microbial ecology, nutrient cycling, physical ocean dynamics, and climate change. [...]."

Source: Wiley Online Library
Authors: Nicholas J. Hawco & Rhea K. Foreman
DOI: 10.1029/2023GL105135

Abstract

"The expansion of oxygen deficient zones (ODZs) within the ocean's interior is anticipated to be a major consequence of anthropogenic climate change, but past changes in ODZs are poorly defined. Recent mapping efforts have revealed plumes of the redox-active metal cobalt within ODZs, driving a basin-scale correlation between high cobalt and low O₂. Here, we investigate the cobalt flux to Equatorial Pacific sediments along the Line Islands Ridge as a novel record of basin-scale fluctuations in ODZ extent. [...]."

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

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鈥搒ea 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 observations from Argo-float-mounted sensors and discrete measurements from ship-based surveys and applied to temperature and salinity fields constructed from the global Argo array. [...]."

Source: Science Direct
Authors: Borhan Bagherpour et al.
DOI: 10.1016/j.cretres.2023.105574

Abstract

"A high鈥搑esolution carbon isotope record of pelagic carbonates (未13Ccarb) from the Zagros Mountains, Iran, documents a 1.8鈥� positive carbon isotope excursion (CIE) in the southeastern Neotethys during the Cenomanian鈥揟uronian transition, corresponding to Ocean Anoxic Event (OAE2). The succession is controlled by biostratigraphy that includes the Rotalipora cushmani, Whiteinella archaeocretacea, and Helvetoglobotruncana helvetica biozones. The CIE is characterized by a positive shift culminating in a first positive peak (at 3.3鈥�), followed by a 1鈥� negative excursion, accompanied by the highest 未18Ocarb values that can be interpreted as the result of a short鈥搇ived global cooling, the Plenus Cold Event. [...]."

Source: Science Direct
Authors: Yiwei Xu et al.
DOI: 10.1016/j.gloplacha.2023.104236

Abstract

"Sea-level changes exert an important control on oceanic circulation and climate evolution. Researchers have proposed that sea-level rise favored accumulation of sediments enriched in organic carbon during oceanic anoxic events (OAEs), although high-frequency sea-level changes and their controlling mechanism have remained poorly constrained. Here we present a detailed sedimentological and geochemical study on Aptian (Lower Cretaceous) shallow-water carbonates of the Dariyan Formation exposed in the Zagros fold belt of southern Iran. [...]."

"The  webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment 鈥� ocean deoxygenation. Organised and hosted by , each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 11 October 2023 No 23

Moderator:
Dimitri Gutierrez
Instituto del Mar del Per煤 (IMARPE), Peru

Speakers:
Montserrat Aldunate
Universidad de Concepci贸n, Chile
"Effect of the oxygen minimum zone on eukaryotic and prokaryotic phytoplankton of the Eastern Tropical North and South Pacific Ocean"

Michelle Graco
Instituto del Mar del Per煤 (IMARPE), Peru
"A Long-term Marine-coastal Observatory of low oxygen and acidification in the upwelling system off Peru"

You can watch the GO₂NE Webinar 11 October 2023 No 23 recording . 

Source: Frontiers in Marine Science
Authors: Lawrence Patrick C. Bernardo et al.
DOI: 10.3389/fmars.2023.1174892

Abstract

"An approach was developed to help evaluate and predict the combined effects of ocean acidification and deoxygenation on calcifying organisms along the coast of Japan. The Coastal and Regional Ocean COmmunity (CROCO) modeling system was set up to couple the Regional Ocean Modeling System (ROMS) to the Pelagic Interaction Scheme for Carbon and Ecosystem Studies (PISCES) biogeochemical model and used to reproduce physical and biochemical processes in the area around Miyako Bay, Iwate Prefecture, Japan. [...]."

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

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 鈮�63 渭M, 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: Science 
Authors: Menghan Li et al.
DOI: 10.1126/sciadv.adh9502

Abstract

"The Cryogenian Sturtian and Marinoan Snowball Earth glaciations bracket a nonglacial interval during which Demosponge and green-algal biomarkers first appear. To understand the relationships between environmental perturbations and early animal evolution, we measured sulfur and mercury isotopes from the Datangpo Formation from South China. Hg enrichment with positive 螖¹⁹⁹Hg excursion suggests enhanced volcanism, potentially due to depressurization of terrestrial magma chambers during deglaciation. [...]."

"The  webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment 鈥� ocean deoxygenation. Organised and hosted by , each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 13 September 2023 No 22

Moderator:
Lisa Levin
Scripps Institution of Oceanography, UC San Diego, USA

Speakers:
Natalya Gallo
University of Bergen and Bjerknes Centre for Climate Research, Norway
"Trophic impacts of ocean deoxygenation: Disruption of bentho-pelagic coupling in oxygen minimum zone regions"

Anne Gro Vea Salvanes
University of Bergen, Norway
"The bearded goby (Sufflogobius bibarbatus): a hypoxia-tolerant little fish member of the Namibian Benguela Ecosystem"

You can watch the GO₂NE Webinar 13 September 2023 No 22 recording . 

Source: Frontiers in Marine Science
Authors: Elizabeth Duskey
DOI: 10.3389/fmars.2023.1206506

Abstract

"Marine hypoxia has had major consequences for both economically and ecologically critical fish species around the world. As hypoxic regions continue to grow in severity and extent, we must deepen our understanding of mechanisms driving population and community responses to major stressors. It has been shown that food availability and habitat use are the most critical components of impacts on individual fish leading to observed outcomes at higher levels of organization. However, differences within and among species in partitioning available energy for metabolic demands 鈥� or metabolic prioritization 鈥� in response to stressors are often ignored. [...]."

Source: European Marine Board
Authors: Marilaure Gr茅goire et al.
DOI: 10.5281/zenodo.7941157

Abstract

"EMB Future Science Brief No. 10 highlights the most recent science on Ocean oxygen, including causes, impacts and mitigation strategies of Ocean oxygen loss, and discusses whether 鈥渆very second breath we take comes from the Ocean鈥�. It closes with key policy, management and research recommendations to address Ocean deoxygenation and communicate more accurately about the role of the Ocean in Earth鈥檚 oxygen. 
The sentence 鈥渆very second breath you take comes from the Ocean鈥� is commonly used in Ocean Literacy and science communication to highlight the importance of Ocean oxygen. [...]."

"On 13 June 2023, the European Marine Board (EMB) organised a webinar to present the new EMB Future Science Brief N掳10 鈥淥cean oxygen: The role of the Ocean in the oxygen we breathe and the threat of deoxygenation鈥�. This 1.5-hour online webinar included a presentation of the document and its main messages, a response to the document by the European Commission and a panel discussion with opportunity for Q&A." 

More information can be found here: .

Source: Wiley Online Library
Authors: Sakae Toyoda et al.
DOI: 10.1029/2022GB007689

Abstract

"The production by microorganisms of nitrous oxide (N2O), a trace gas contributing to global warming and stratospheric ozone depletion, is enhanced around the oceanic oxygen minimum zones (OMZs). The production constitutes an important source of atmospheric N2O. Although an OMZ is found in the northern part of the eastern Indian Ocean, the Bay of Bengal (BoB), two earlier studies conducted during the later phase of winter monsoon (February) and spring intermonsoon (March鈥揂pril) found quite different magnitudes of N2O accumulation. [...]."

Source: Science Direct
Authors: Bokun Chen et al.
DOI: 10.1016/j.scitotenv.2023.164032

Abstract

"Anthropogenic activities and climate change are exacerbating marine deoxygenation. Apart from aerobic organisms, reduced O2 also affects photoautotrophic organisms in the ocean. This is because without available O2, these O2 producers cannot maintain their mitochondrial respiration, especially under dim-light or dark conditions, which may disrupt the metabolism of macromolecules including proteins. We used growth rate, particle organic nitrogen and protein analyses, proteomics, and transcriptomics to determine cellular nitrogen metabolism of the diatom Thalassiosira pseudonana grown under three O2 levels in a range of light intensities at nutrient-rich status. [...]."

Source: Biogeosciences
Authors: Marco Fusi et al.
DOI: 10.5194/bg-20-3509-2023

Abstract

"Oxygen availability is a pivotal factor for ecosystem functioning and the resistance of organisms to the effect of climate change in aquatic habitats. Although extensive work has been done to assess the effect of oxygen on marine and freshwater biota, many studies have not captured the ecological importance of oxygen variations. Overlooking the fluctuating nature of oxygen may cause potential biases in the design and implementation of management policies for aquatic habitats. Conceptual perspectives on the dynamic nature of oxygen fluctuations have been raised in the scientific community in order to enhance the understanding of the effect of oxygen on the physiology and the ecology of aquatic species as well as the biogeochemical functioning of their ecosystems. [...]."

Source: Science Direct
Authors: Ruixiang Zhai et al.
DOI: 10.1016/j.gloplacha.2023.104182

Abstract

"The Cretaceous Oceanic Anoxic Event 2 (OAE2) is a greenhouse episode of severe marine anoxia at the Cenomanian-Turonian boundary. This time interval is characterized by rising sea surface temperature, enhanced marine biological productivity, and widespread occurrence of organic-rich black shales. With an export of biological production to the deep ocean, organisms consume vast amounts of oxygen and subsequently utilize nitrate and sulfate as electron acceptors in organic matter degradation, thereby affecting biogeochemical cycles of nitrogen and sulfur. [...]."

Source: Biogeosciences
Authors: Nicolaas Glock
DOI: 10.5194/bg-20-3423-2023

Abstract

"The oceans are losing oxygen (O₂), and oxygen minimum zones are expanding due to climate warming (lower O₂ solubility) and eutrophication related to agriculture. This trend is challenging for most marine taxa that are not well adapted to O₂ depletion. For other taxa this trend might be advantageous because they can withstand low O₂ concentrations or thrive under O₂-depleted or even anoxic conditions. Benthic foraminifera are a group of protists that include taxa with adaptations to partly extreme environmental conditions. [...]."

Source: Nature
Authors: Liao Chang et al.
DOI: 10.1038/s41467-023-40452-1

Abstract

"Reconstructions of ocean oxygenation are critical for understanding the role of respired carbon storage in regulating atmospheric CO2. Independent sediment redox proxies are essential to assess such reconstructions. Here, we present a long magnetofossil record from the eastern Indian Ocean in which we observe coeval magnetic hardening and enrichment of larger, more elongated, and less oxidized magnetofossils during glacials compared to interglacials over the last ~900 ka. Our multi-proxy records of redox-sensitive magnetofossils, trace element concentrations, and benthic foraminiferal 螖未13C consistently suggest a recurrence of lower O2 in the glacial Indian Ocean over the last 21 marine isotope stages, as has been reported for the Atlantic and Pacific across the last glaciation. [...]."

Source: Nature
Authors: Irene H. Zhang et al.
DOI: 10.1038/s43705-023-00284-y

Abstract

"Oxygen deficient zones (ODZs) account for about 30% of total oceanic fixed nitrogen loss via processes including denitrification, a microbially mediated pathway proceeding stepwise from NO3鈥� to N2. This process may be performed entirely by complete denitrifiers capable of all four enzymatic steps, but many organisms possess only partial denitrification pathways, either producing or consuming key intermediates such as the greenhouse gas N2O. Metagenomics and marker gene surveys have revealed a diversity of denitrification genes within ODZs, but whether these genes co-occur within complete or partial denitrifiers and the identities of denitrifying taxa remain open questions. [...]."

Source: Nature
Authors: Davide Ciccarese et al.
DOI: 10.1038/s43247-023-00935-x

Abstract

"Sinking marine particles drive the biological pump that naturally sequesters carbon from the atmosphere. Despite their small size, the compartmentalized nature of particles promotes intense localized metabolic activity by their bacterial colonizers. Yet the mechanisms promoting the onset of denitrification, a metabolism that arises once oxygen is limiting, remain to be established. Here we show experimentally that slow sinking aggregates composed of marine diatoms鈥攊mportant primary producers for global carbon export鈥攕upport active denitrification even among bulk oxygenated water typically thought to exclude anaerobic metabolisms. [...]."

Source: Science Direct
Authors: Wei Tang et al.
DOI: 10.1016/j.jseaes.2023.105659

Abstract

"Marine anoxia during the Late Triassic has mostly been reported from the western Tethysand Panthalassa, which were near the Central Atlantic Magmatic Province (CAMP), but whether it developed in global open oceans (e.g., the eastern Tethys) is unknown. Whether the marine anoxia was global or regional requires more research. Here, we present carbonate-associated sulfate (CAS) and pyrite 未34Spy data for the Late Triassic鈥揈arly Jurassic interval from the Wenquan Section in Qiantang Basin, Tibet. [...]."

Source: Nature
Authors: Haiyang Wang et al.
DOI: 10.1038/s41467-023-39962-9

Abstract

"The largest negative inorganic carbon isotope excursion in Earth鈥檚 history, namely the Ediacaran Shuram Excursion (SE), closely followed by early animal radiation, has been widely interpreted as a consequence of oceanic oxidation. However, the primary nature of the signature, source of oxidants, and tempo of the event remain contested. Here, we show that carbonate-associated sulfate (CAS) from three different paleocontinents all have conspicuous negative 17O anomalies (螖鈥�17OCAS values down to 鈭�0.53鈥�) during the SE. [...]."

Source: Science Direct
Authors: Erik Wolfgring et al.
DOI: 10.1016/j.cretres.2023.105555

Abstract

"At Site U1516 (Mentelle Basin, southeast Indian Ocean, offshore western Australia), the International Ocean Discovery Program (IODP) Expedition 369 recovered an almost complete pelagic record of the Upper Cretaceous, including the Oceanic Anoxic Event 2 (OAE 2). To better understand paleoenvironmental changes across OAE 2, 32 samples were analysed for benthic foraminiferal abundance data that represent one of the few benthic foraminiferal datasets spanning the OAE 2 in the southern high latitudes. [...]."

Source: Science Direct
Authors: Yufei Hao et al.
DOI: 10.1016/j.jseaes.2023.105670

Abstract

"The high enrichment of redox-sensitive elements (RSEs), Mo, U, V, and Cr, in Ediacaran shales was attributed to the Neoproterozoic Oxygenation Event (NOE). However, recent studies have shown that contemporaneous shales from NW Canada do not exhibit RSE enrichment, whereas those from South China exhibit varying degrees of RSE enrichment. Here we investigate RSE records in a broader spatial and temporal distribution of shales within the Ediacaran Doushantuo Formation from South China. [...]."

Source: Frontiers in Marine Science
Authors: Florian B枚rgel et al.
DOI: 10.3389/fmars.2023.1174039

Abstract

"Over the last 1,000 years, changing climate strongly influenced the ecosystem of coastal oceans such as the Baltic Sea. Sedimentary records revealed that changing temperatures could be linked to changing oxygen levels, spreading anoxic, oxygen-free areas in the Baltic Sea. However, the attribution of changing oxygen levels remains to be challenging. This work simulates a preindustrial period of 850 years, covering the Medieval Climate Anomaly (MCA) and the Little Ice Age using a coupled physical-biogeochemical model. [...]."

Source: Biogeosciences
Authors: Kyle E. Hinson et al.
DOI: 10.5194/bg-20-1937-2023

Abstract

"Multiple climate-driven stressors, including warming and increased nutrient delivery, are exacerbating hypoxia in coastal marine environments. Within coastal watersheds, environmental managers are particularly interested in climate impacts on terrestrial processes, which may undermine the efficacy of management actions designed to reduce eutrophication and consequent low-oxygen conditions in receiving coastal waters. However, substantial uncertainty accompanies the application of Earth system model (ESM) projections to a regional modeling framework when quantifying future changes to estuarine hypoxia due to climate change. [...]."

Source: Science Direct
Authors: Andrea Gori et al.
DOI: 10.1016/j.dsr.2023.104052

Abstract

"Large, well-developed and flourishing reefs dominated by the cold-water coral Desmophyllum pertusum have recently been discovered along the Angola margin in the southeastern Atlantic Ocean living under very low oxygen concentrations (0.6鈥�1.5 mL L鈭�1). This study assessed the respiration rates of this coral in a short-term (10 days) aquarium experiment under naturally low oxygen concentrations (1.4 卤 0.5 mL L鈭�1) as well as under saturated oxygen concentrations (6.1 卤 0.6 mL L鈭�1). We found no significant difference in respiration rates between the two oxygen concentrations. [...]."

Source: Science Direct
Authors: Ricardo D. Monedero-Contreras et al.
DOI: 10.1016/j.palaeo.2023.111601

Abstract

"Modern marine settings are experiencing rapid deoxygenation mainly forced by global warming and anthropogenic eutrophication. Therefore, studies that assess the role of climate variability in large spatiotemporal deoxygenations during past climate changes are needed to better comprehend the consequences of the current global warming and ocean deoxygenation. [...]."

Source: Science Direct
Authors: Cheng Qian et al.
DOI: 10.1016/j.scitotenv.2023.163568

Abstract

"Hypoxia and ocean warming are two mounting global environmental threats influencing marine ecosystems. However, the interactive effects of rising temperature and depleted dissolved oxygen (DO) on marine protists remains unknown. Here, we conducted a series of laboratory experiments on four protozoa with distinct cell sizes to investigate the combined effects of temperature (19, 22, 25, 28, and 31 掳C) and oxygen availability (hypoxia, 2 mg DO L鈭�1 and normoxia, 7 mg DO L鈭�1) on their physiological performances (i.e., growth, ingestion, and respiration rates). The hypoxia-induced inhibition in three physiological rates increased with the biovolume of the protists. [...]."

Source: Nature
Authors: Anya V. Hess et al.
DOI: 10.1038/s41586-023-06104-6

Abstract

"The oxygen content of the oceans is susceptible to climate change and has declined in recent decades, with the largest effect in oxygen-deficient zones (ODZs), that is, mid-depth ocean regions with oxygen concentrations <5 渭mol kg鈭�1 (ref.). Earth-system-model simulations of climate warming predict that ODZs will expand until at least 2100. The response on timescales of hundreds to thousands of years, however, remains uncertain. Here we investigate changes in the response of ocean oxygenation during the warmer-than-present Miocene Climatic Optimum (MCO; 17.0鈥�14.8 million years ago (Ma)). [...]."

Source: MDPI
Authors: Hongsik Kim et al.
DOI: 10.3390/fishes8060316

Abstract

"Oxygen is crucial for the survival of marine species. Yet, the ocean has experienced a loss of approximately 2% of its oxygen inventory since the last century, resulting in adverse impacts on marine life and ecosystems. In particular, changes in the gap between the supply and demand for dissolved oxygen lead to physiological and ecological variations, which cause alterations in habitats and food webs for fish and ecosystem services. These changes vary over time and by region, and the heterogeneous characteristics of marine species bring about non-linear consequences to human society. [...]."

GOOD News is the newsletter that keeps you up to date on the highlights, events, announcements, and opportunities in the  and the . Compiled by the GO₂NE Secretariat at the , the content of GOOD News is provided by the ocean deoxygenation community. 

In the third issue of GOOD News, you can read more about:

• GO2NE working group annual in-person meeting
• ECCWO-5: Ocean Deoxygenation: Physical, Biogeochemical and Ecological Research Advances and Future Needs 
• Update of the Global Ocean Oxygen Database and Atlas (GO2DAT) project
• Spotlighting Ocean Deoxygenation at World Oceans Day 鈥� June 2023
• GO2DAT at the International Ocean Data Conference-II 2023 
• GO2NE webinar series
• Events, announcements, and opportunities 

Source: Nature
Authors: Folco Giomi et al.
DOI: 10.1038/s41561-023-01217-z

Abstract

"The decline of dissolved oxygen in the oceans could be detrimental to marine life and biogeochemical cycles. However, predicting future oxygen availability with models that mainly focus on temporal and spatial large-scale mean values could lead to incorrect predictions. Marine ecosystems are strongly influenced by short temporal- and small spatial-scale oxygen fluctuations. Large-scale modelling neglects fluctuations, which include the pervasive occurrence of high oxygen supersaturation on a daily time scale in productive ecosystems such as coral reefs, seagrass meadows and mangrove forests and the spatial heterogeneity in oxygen availability at microclimatic scales. [...]."

Source: Biogeosciences
Authors: Anne L. Mor茅e et al.
DOI: 10.5194/bg-20-2425-2023

Abstract

"Ocean temperature and dissolved oxygen shape marine habitats in an interplay with species' physiological characteristics. Therefore, the observed and projected warming and deoxygenation of the world's oceans in the 21st century may strongly affect species' habitats. Here, we implement an extended version of the Aerobic Growth Index (AGI), which quantifies whether a viable population of a species can be sustained in a particular location. We assess the impact of projected deoxygenation and warming on the contemporary habitat of 47 representative marine species covering the epipelagic, mesopelagic, and demersal realms. [...]."

Source: Wiley Online Library
Authors: Haichao Guo et al.
DOI: 10.1029/2022GL102645

Abstract

"Quantifying changes in oceanic aerobic respiration is essential for understanding marine deoxygenation. Here we use an Earth system model to investigate if and to what extent oxygen utilization rate (OUR) can be used to track the temporal change of true respiration (Rtrue). Rtrue results from the degradation of particulate and dissolved organic matter in the model ocean, acting as ground truth to evaluate the accuracy of OUR. Results show that in thermocline and intermediate waters of the North Atlantic Subtropical Gyre (200鈥�1,000 m), vertically integrated OUR and Rtrue both decrease by 0.2 molO2/m2/yr from 1850 to 2100 under global warming. [...]."

"The  webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment 鈥� ocean deoxygenation. Organised and hosted by , each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 26 July 2023 No 21

Moderator:
Damodar Shenoy
CSIR-National Institute of Oceanography, Goa, India

Speakers:
Sudheesh Valliyodan
Central University of Kerala, India
"Oxygen Minimum Zone dynamics of eastern Arabian Sea"

Zouhair Lachkar
New York University Abu Dhabi, United Arab Emirates
"Recent and future trends in the Arabian Sea oxygen minimum zone: processes and uncertainties"

You can watch the GO₂NE Webinar 26 July 2023 No 21 recording . 

Source: Science Direct
Authors: Wang Zheng et al.
DOI: 10.1016/j.epsl.2023.118175

Abstract

"Widespread oceanic anoxia marked by globally extensive deposition of organic-rich black shale during the Late Devonian was a major factor in the mass extinctions at the Frasnian-Famennian (FFB, 鈭�372 million years ago) and Devonian-Carboniferous boundaries (DCB, 鈭�359 million years ago), although the triggers for these deoxygenation events are still under debate. Here, we apply a novel paleoredox proxy, Hg isotopes, to investigate Late Devonian ocean redox variation and its causes. [...]."

Source: Science Direct
Authors: Pavel Kabanov et al.
DOI: 10.1016/j.earscirev.2023.104415

Abstract

"This paper reviews global records of anoxic events of the Middle Devonian 鈥� earliest Mississippian, as well as the possible triggers and controls of these events. These 鈥渁noxic events鈥� are complex multistage paleoenvironmental disturbances manifested in multiple proxies, which we showcase with the Horn River Group (HRG) 鈥� a succession of basinal organic-rich shales and cherts deposited during the latest Eifelian 鈥� earliest Late Frasnian(鈭�386鈥�373 My ago) on the western continental margin of Laurentia near the paleo-equator. [...]."

Source: Wiley Online Library
Authors: Mingze Ye et al.
DOI: 10.1029/2023GL103598

Abstract

"The availability of oxygen and nutrients during the Mesoproterozoic (1.6鈥�1.0 Ga) is thought to influence the rate of eukaryote evolution. The cause of the transition from low productivity in the upper Wumishan Formation to organic-rich sediments in the Hongshuizhuang Formation remains unknown. We report FeHR/FeT, Fepy/FeHR, MoEF, UEF, VEF, and [Ce/Ce*]SN in one core of the Yanliao Basin to study the redox evolution and compare it with other sections in different depths of the Yanliao Basin to get clues of the spatial and temporal redox heterogeneity. [...]."

"The  webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment 鈥� ocean deoxygenation. Organised and hosted by , each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 19 June 2023 No 20

Moderator:
Andreas Oschlies
黑料视频 Helmholtz Centre for Ocean Research Kiel, Germany

Speakers:
Patricia Handmann
Lhyfe, France
"Potential Environmental Services of Offshore Hydrogen Production - Ocean Reoxygenation" 

Bo Gustafsson 
Stockholm University Baltic Sea Centre, Sweden
"Mitigation of eutrophication and oxygen depletion in the Baltic Sea; challenges for science and management"

You can watch the GO₂NE Webinar 19 June 2023 No 20 recording . 

Source: Science Direct
Authors: Yijun Xiong et al.
DOI: 10.1016/j.gca.2023.04.032

Abstract

"The formation of green rust (GR; a mixed ferric/ferrous hydroxide) and vivianite (ferrous phosphate) are likely to have exerted a major control on phosphorus (P) cycling in ancient anoxic oceans. However, the factors that influence the formation of these minerals under different chemical conditions are poorly constrained, which limits understanding of the pathways that ultimately result in P drawdown and retention in anoxic sediments. This, in turn, limits understanding of P cycling in anoxic oceans and hence potential productivity feedbacks. [...]."

Source: Science Direct
Authors: Guangyao Cao et al.
DOI: 10.1016/j.gloplacha.2023.104129

Abstract

"The Ordovician-Silurian transition (OST) is a critical geological interval, during which dramatic climatic, environmental and biological changes occurred. Although expanded euxinic conditions have been regarded as one of the main causes of Late Ordovician mass extinction (LOME), the controls of euxinia remain the topic of debate. In this study, we evaluate the paleosalinity conditions of the inner Yangtze Sea (IYS) during the OST using a combination of paleosalinity proxies (B/Ga, Sr/Ba, and S/TOC). [...]."

Source: Wiley Online Library
Authors: Pamela Linford et al.
DOI: 10.1029/2022GB007688

Abstract

"In recent decades, global dissolved oxygen (DO) measurements have registered a decrease of 鈭�1%鈥�2% in oxygen content, raising concerns regarding the negative impacts of ocean deoxygenation on marine life and the greenhouse gas cycle. By combining in situ data from 2016 to 2022, satellite remote sensing, and outputs from a physical-biogeochemical model, we revealed the deoxygenation process in the Patagonian fjords for the first time. Deoxygenation was associated with the advection of equatorial subsurface water (ESSW) mass into the northern region of Patagonia. [...]."

Source: Nature
Authors: Julia Anstett et al.
DOI: 10.1038/s41597-023-02222-y

Abstract

"Oxygen-deficient marine waters referred to as oxygen minimum zones (OMZs) or anoxic marine zones (AMZs) are common oceanographic features. They host both cosmopolitan and endemic microorganisms adapted to low oxygen conditions. Microbial metabolic interactions within OMZs and AMZs drive coupled biogeochemical cycles resulting in nitrogen loss and climate active trace gas production and consumption. Global warming is causing oxygen-deficient waters to expand and intensify. [...]."

Source: Science Direct
Authors: Kaidian Zhang et al.
DOI: 10.1016/j.marpolbul.2023.114897

Abstract

"Loss of oxygen in the ocean is accelerating and threatening the coral reef ecosystem. In this study, the impacts of hypoxia on the scleractinian coral Pocillopora damicornis were explored. The algal symbiont density, chlorophyll a + c2 content, energy consumption of corals, as well as energy available and consumption of their symbionts, decreased significantly post hypoxia stress. Meanwhile, the malondialdehyde contents in corals and symbionts, together with the caspase-3 activation level in corals, increased significantly in response to hypoxia stress. [...]."

Source: Wiley Online Library
Authors: Jane C. Y. Wong et al.
DOI: 10.1002/lno.12367

Abstract

"It is commonly known that phytoplankton have a pivotal role in marine biogeochemistry and ecosystems as carbon fixers and oxygen producers, but their response to deoxygenation has scarcely been studied. Nonetheless, in the major oceanic oxygen minimum zones (OMZs), all surface phytoplankton groups, regardless of size, disappear and are replaced by unique cyanobacteria lineages below the oxycline. To develop reasonable hypotheses to explain this pattern, we conduct a review of available information on OMZ phytoplankton, and we re-analyze previously published data (flow cytometric and hydrographic) on vertical structure of phytoplankton communities in relation to light and O₂ levels. [...]."

Source: Science Direct
Authors: Libby J. Robinson et al.
DOI: 10.1016/j.palaeo.2023.111496

Abstract

"Oceanic Anoxic Events (OAEs) are important geological events that may be analogues to future climate-driven deoxygenation of our oceans. Much of the global ocean experienced anoxic conditions during the Cenomanian鈥揟uronian OAE (OAE2; 鈭�94 Ma), whereas the Western Interior Seaway (WIS) experienced oxygenation at this time. Here, organic geochemical and palynological data generated from Cenomanian鈥揟uronian age sediments from five sites in the WIS are used to investigate changing redox and ecological conditions across differing palaeoenvironments and palaeolatitudes. [...]."

Source: Science Direct
Authors: Huyue Song et al.
DOI: 10.1016/j.epsl.2023.118128

Abstract

"The timing and causation of the Capitanian (late Middle Permian) biocrisis remain controversial. Here, a detailed uranium-isotopic (未238U) profile was generated for the mid-Capitanian to lower Wuchiapingian of the Penglaitan section (the Guadalupian/Lopingian Permian global stratotype) in South China for the purpose of investigating relationships between the biocrisis and coeval oceanic anoxic events (OAEs). Negative 未238U excursions indicate two distinct OAEs, a mid-Capitanian (OAE-C1) and an end-Capitanian (OAE-C2) event. [...]."

Source: Springer Nature
Authors: Tarek Anan & Adam El-Shahat 
DOI: 10.1007/978-3-030-95637-0_7

Abstract

"Oceanic anoxic events (OAEs) are considered as periods of oxygen deficiency in many oceans; accompanied by accumulation of organic-rich black shales. Mesozoic anoxic events were recognized based on the presence of black shales that are rich in organic matter. The most significant anoxic events during the Mesozoic are the Early Toarcian, the Early Aptian, and the Cenomanian鈥揟uronian. The less significant events are the Valanginian-Hauterivian, the Hauterivian-Barremian, the Aptian-Albian, the Late Albian, the Albian-Cenomanian, and the Coniacian-Santonian. [...]."

Source: Science Direct
Authors: Wolfgang Ruebsam & Lorenz Schwark
DOI: 10.1016/j.gloplacha.2023.104117

Abstract

"The Cenomanian-Turonian (Late Cretaceous) climate warming was closely coupled to profound perturbations of biogeochemical cycles and ecosystems. The occurrence of organic matter-rich sediments across various depositional environments of the proto-North Atlantic hereby marks severe oxygen-deficient conditions, culminating in Oceanic Anoxic Event (OAE 2) at the Cenomanian/Turonian boundary. Here we combine bulk, isotope and molecular geochemical techniques to characterize trends in organic matter accumulation and its relationship to biogeochemical cycling (nitrogen, carbon) and marine phytoplankton community shifts at the Tarfaya shelf, situated at the northeastern margin of the proto-north Atlantic. [...]."

Source: Science Direct
Authors: Dag L. Aksnes et al.
DOI: 10.1016/j.ecss.2023.108286 

Abstract

"The exchange of water masses between deep fjords and the open ocean is commonly constrained by a topographical barrier called the sill. While fjord water above the sill depth communicates relatively freely with the open ocean, water below the sill depth is caught inside the fjord basin. This basin water may remain stagnant in deep fjords for many successive years. During these periods, the biological consumption of dissolved oxygen is larger than the supply of new oxygen, and the fjord basin might experience hypoxia and even anoxia. [...]."

Source: Science Direct
Authors: Yudong Jia et al.
DOI: 10.1016/j.aquatox.2023.106502

Abstract

"Dissolved oxygen concentrations both in the open ocean and coast have been declining due to the interaction of global climate change and human activity. Fish have evolved different adaptative strategies to cope with possibly damage induced by hypoxic environments. Black rockfish as important economic fish widely reared in the offshore sea cage, whereas related physiological response subject to hypoxia stress remained unclear. In this study, hepatic anti-oxidant enzymes (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GSH-Px]), aminotransferase (AST) and alanine aminotransferase (ALT) activities, lipid peroxidation (LPO), malondialdehyde (MDA) and glutathione (GSH) content, immunological parameters and the expression of apoptosis (bax, bcl2, p53, caspase3, xiap) and immune-related genes (c3, il-1尾, ccl25, saa, hap, isg15) of black rockfish were determined during hypoxia and reoxygenation to illustrate the underlying defense response mechanisms. [...]."

Source: Science Direct
Authors: Rong Hu et al.
DOI: 10.1016/j.quascirev.2023.108028

Abstract

"Deep-sea oxygen concentrations reflect combined effects of air-sea exchange in high-latitude surface waters, ventilation through ocean circulation and the organic carbonremineralization at depth. Reconstruction of past bottom water oxygen (BWO) concentrations has been challenging due to limitations of each existing BWO proxy whose fidelity may be complicated by diagenetic or depositional factors. Therefore, evaluations on BWO changes with multi-proxy approach are always preferred. In this study, we exploit the authigenic uranium content on mixed planktonic foraminiferal coatings as a BWO proxy by presenting new foraminiferal U/Ca and U/Mn ratios of the Holocene and last glacial maximum (LGM) sediments from 54 sites throughout the Pacific Ocean, covering a range of modern BWO from 8 to 210 渭mol/kg. [...]."

Source: Science Direct
Authors: Zhaozhao Tan et al.
DOI: 10.1016/j.chemgeo.2023.121410

Abstract

"The Mo isotope composition of late Ediacaran global seawater and the global extent of ocean oxygenation are still debated due to the complex controls on sedimentary Mo isotope compositions and the rarity with which sediments directly capture global seawater Mo isotope compositions. Deep-water sulfidic sediments from modern severely restricted basins like the Black Sea have the best chance of capturing global seawater Mo isotope compositions. However, few studies have focused on sedimentary Mo isotope variations and their causes in late Ediacaran restricted basins. [...]."

Source: MDPI
Authors: Jaquelino Varela et al.
DOI: 10.3390/biology12040577

Abstract

"Climate change is leading to the loss of oxygen content in the oceans and endangering the survival of many marine species. Due to sea surface temperature warming and changing circulation, the ocean has become more stratified and is consequently losing its oxygen content. Oviparous elasmobranchs are particularly vulnerable as they lay their eggs in coastal and shallow areas, where they experience significant oscillations in oxygen levels. Here, we investigated the effects of deoxygenation (93% air saturation) and hypoxia (26% air saturation) during a short-term period (six days) on the anti-predator avoidance behavior and physiology (oxidative stress) of small-spotted catshark (Scyliorhinus canicula) embryos. [...]."

Source: Wiley Online Library 
Authors: Xin Sun et al.
DOI: 10.1029/2022GB007548

Abstract

"Fixed nitrogen limits primary productivity in most areas of the surface ocean. Nitrite oxidation is the main source of nitrate, the most abundant form of inorganic fixed nitrogen. Even though known as an aerobic process, nitrite oxidation is not always stimulated by increased oxygen concentration, and nitrite oxidation occurs in layers of oxygen minimum zones (OMZs) where oxygen is not detectable. Nitrite-oxidizing bacteria, known since their original isolation as aerobes, were also detected in these layers. Whether and how nitrite oxidation is occurring in the anoxic seawater is debated. [...]."

Source: Wiley Online Library 
Authors: Silvia Pajares et al.
DOI: 10.1111/1462-2920.16362

Abstract

"Dissolved oxygen regulates microbial distribution and nitrogen cycling and, therefore, ocean productivity and Earth's climate. To date, the assembly of microbial communities in relation to oceanographic changes due to El Ni帽o Southern Oscillation (ENSO) remains poorly understood in oxygen minimum zones (OMZ). The Mexican Pacific upwelling system supports high productivity and a permanent OMZ. Here, the spatiotemporal distribution of the prokaryotic community and nitrogen-cycling genes was investigated along a repeated transect subjected to varying oceanographic conditions associated with La Ni帽a in 2018 and El Ni帽o in 2019. [...]."

Source: Science Direct
Authors: Johann M眉ller et al.
DOI: 10.1016/j.gloplacha.2023.104067 

Abstract

"Ocean anoxia was one of the key killing mechanisms responsible for the end-Permian mass extinction (鈭�252 Ma). However, the temporal evolution and the triggering mechanisms of the end-Permian anoxia are controversial, with the current view being that the water column deoxygenation was a spatially and temporally heterogeneous event. Here, we use cerium-anomalies, uranium contents and rare earth element and yttrium (REY) compositions measured on the carbonate fraction of samples from two marine sections in Armenia and South China to constrain the evolution of end-Permian marine anoxia. [...]."

Source: Nature 
Authors: Ariel K. Pezner et al.
DOI: 10.1038/s41558-023-01619-2

Abstract

"Ocean deoxygenation is predicted to threaten marine ecosystems globally. However, current and future oxygen concentrations and the occurrence of hypoxic events on coral reefs remain underexplored. Here, using autonomous sensor data to explore oxygen variability and hypoxia exposure at 32 representative reef sites, we reveal that hypoxia is already pervasive on many reefs. Eighty-four percent of reefs experienced weak to moderate (鈮�153鈥壜祄ol O2 kg鈭�1to 鈮�92鈥壜祄ol O2 kg鈭�1) hypoxia and 13% experienced severe (鈮�61鈥壜祄ol O2 kg鈭�1) hypoxia. Under different climate change scenarios based on four Shared Socioeconomic Pathways (SSPs), we show that projected ocean warming and deoxygenation will increase the duration, intensity and severity of hypoxia, with more than 94% and 31% of reefs experiencing weak to moderate and severe hypoxia, respectively, by 2100 under SSP5-8.5. [...]."

Source: Cambridge University Press
Authors: Minhan Dai et al. 
DOI: 10.1017/cft.2023.7

Abstract

"Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great efforts to reduce nutrient loading and mitigate associated environmental damages. Symptoms of this crisis have appeared to spread rapidly, reaching developing countries in Asia with emergences in Southern America and Africa. The pace of changes and the underlying drivers remain not so clear. To address the gap, we review the up-to-date status and mechanisms of eutrophication and hypoxia in global coastal oceans, upon which we examine the trajectories of changes over the 40 years or longer in six model coastal systems with varying socio-economic development statuses and different levels and histories of eutrophication. [...]."

Source: Nature 
Authors: Mingyu Zhao et al.
DOI: 10.1038/s41561-023-01133-2

Abstract

"Photosynthesis produces molecular oxygen, but it is the burial of organic carbon in sediments that has allowed this O2 to accumulate in Earth鈥檚 atmosphere. Yet many direct controls on the preservation and burial of organic carbon have not been explored in detail. For modern Earth, it is known that reactive iron phases are important for organic carbon preservation, suggesting that the availability of particulate iron could be an important factor for the oxygenation of the oceans and atmosphere over Earth history. Here we develop a theoretical model to investigate the effect of mineral鈥搊rganic preservation on the oxygenation of the Earth, supported by a proxy compilation for terrigenous inputs and the burial of reactive iron phases, and find that changes to the rate of iron input to the global ocean constitute an independent control on atmosphere鈥搊cean O2 and marine sulfate levels. [...]."

Source: Science Direct
Authors: Yadhav Abhilesh Imrit et al.
DOI: 10.1016/j.rsma.2023.102815

Abstract

"Sea water samples were collected at five stations around Mauritius namely Flic-en-Flac, Albion, Mont Choisy, Trou-d鈥橢au-Douce and La Cambuse over 12 months from July 2021 to June 2022 for the analysis of dissolved oxygen (D.O), pH and Total alkalinity (). Albion was the only open water system whereas the others were lagoons. Summer was from November 2021 to April 2022 while the period from July 2021 to October 2021, May 2022 and June 2022 were considered to be winter. [...]."

Source: Nature 
Authors: Swapan K. Sahoo et al.
DOI: 10.1038/s41586-023-05716-2

Abstract

"The Devonian鈥揅arboniferous transition marks a fundamental shift in the surface environment primarily related to changes in ocean鈥揳tmosphere oxidation states, resulting from the continued proliferation of vascular land plants that stimulated the hydrological cycle and continental weathering, glacioeustasy, eutrophication and anoxic expansion in epicontinental seas, and mass extinction events. Here we present a comprehensive spatial and temporal compilation of geochemical data from 90 cores across the entire Bakken Shale (Williston Basin, North America). [...]."

Source: Science Direct
Authors: Min Ren & Ruifan Li
DOI: 10.1016/j.sedgeo.2023.106343

Abstract

"The Rare Earth Element (REE) systematics of the post-Marinoan cap dolostones reflect the marine redox conditions and chemistry in the immediate aftermath of the snowball Earth. Rare earth elements and yttrium (REY) compositions in the Doushantuo cap dolostones that directly overlie Nantuo glacial diamictites in south China are determined from the inner shelf to the slope. In general, shale-normalized REY patterns (REYSN) of the cap dolostones show significant fractionations that are characterized by light REE depletion, slight middle REE enrichment relative to the light and heavy REEs, positive Eu anomalies, and slightly super-chondritic Y/Ho ratios. [...]."

Source: Nature
Authors: Massimiliano Molari et al.
DOI: 10.1038/s41564-023-01342-w

Abstract

"Members of the bacterial genus Sulfurimonas (phylum Campylobacterota) dominate microbial communities in marine redoxclines and are important for sulfur and nitrogen cycling. Here we used metagenomics and metabolic analyses to characterize a Sulfurimonasfrom the Gakkel Ridge in the Central Arctic Ocean and Southwest Indian Ridge, showing that this species is ubiquitous in non-buoyant hydrothermal plumes at Mid Ocean Ridges across the global ocean. One Sulfurimonas species, USulfurimonas pluma, was found to be globally abundant and active in cold (<0鈭�4鈥壜癈), oxygen-saturated and hydrogen-rich hydrothermal plumes. [...]."

Source: Frontiers in Physiology
Authors: Mariano Mart铆nez et al.
DOI: 10.3389/fphys.2023.1083240

Abstract

"When an organism makes a long-distance transition to a new habitat, the associated environmental change is often marked and requires physiological plasticity of larvae, juveniles, or other migrant stages. Exposing shallow-water marine bivalves (Aequiyoldia cf. eightsii) from southern South America (SSA) and the West Antarctic Peninsula (WAP) to changes in temperature and oxygen availability, we investigated changes in gene expression in a simulated colonization experiment of the shores of a new continent after crossing of the Drake Passage, and in a warming scenario in the WAP. [...]."

Source: Wiley Online Library 
Authors: Ana C. Franco et al.
DOI: 10.1029/2022GL101857

Abstract

"Bottom waters of the northeast Pacific continental shelf naturally experience localized hypoxic conditions, with significant influences on food webs and biogeochemical cycling. In August 2021, extreme hypoxia was detected from several measurement platforms along the southern British Columbia continental shelf, with oxygen concentration <60 渭mol kg^鈭�1, and a difference from the seasonal climatology of more than 2 standard deviations. Early and intense remote upwelling and local density shifts were associated with an anomalously strong spring phytoplankton bloom, which likely stimulated localized respiration of subsurface organic matter. [...]."

Source: Nature 
Authors: Jerry F. Tjiputra et al.
DOI: 10.1038/s41598-023-30159-0

Abstract

"Robust detection of anthropogenic climate change is crucial to: (i) improve our understanding of Earth system responses to external forcing, (ii) reduce uncertainty in future climate projections, and (iii) develop efficient mitigation and adaptation plans. Here, we use Earth system model projections to establish the detection timescales of anthropogenic signals in the global ocean through analyzing temperature, salinity, oxygen, and pH evolution from surface to 2000 m depths. For most variables, anthropogenic changes emerge earlier in the interior ocean than at the surface, due to the lower background variability at depth. [...]."

Source: MDPI
Authors: Donat-P. H盲der & Kunshan Gao
DOI: 10.3390/w15040817

Abstract

"Aquatic ecosystems are responsible for about 50% of global productivity. They mitigate climate change by taking up a substantial fraction of anthropogenically emitted CO2 and sink part of it into the deep ocean. Productivity is controlled by a number of environmental factors, such as water temperature, ocean acidification, nutrient availability, deoxygenation and exposure to solar UV radiation. Recent studies have revealed that these factors may interact to yield additive, synergistic or antagonistic effects. While ocean warming and deoxygenation are supposed to affect mitochondrial respiration oppositely, they can act synergistically to influence the migration of plankton and N2-fixation of diazotrophs. [...]."

Source: PNAS
Authors: Xianhui S. Wan et al.
DOI: 10.1073/pnas.2220697120

Abstract

"The ocean is a net source of the greenhouse gas and ozone-depleting substance, nitrous oxide (N2O), to the atmosphere. Most of that N2O is produced as a trace side product during ammonia oxidation, primarily by ammonia-oxidizing archaea (AOA), which numerically dominate the ammonia-oxidizing community in most marine environments. The pathways to N2O production and their kinetics, however, are not completely understood. Here, we use 15N and 18O isotopes to determine the kinetics of N2O production and trace the source of nitrogen (N) and oxygen (O) atoms in N2O produced by a model marine AOA species, Nitrosopumilus maritimus. [...]."

Source: Marine Climate Change Impacts Partnership  
Authors: Claire Mahaffey et al.
DOI: 10.14465/2023.reu07.oxy

Abstract

"What is already happening

• Since the 1960s, the global oceanic oxygen content has declined by more than 2%.
• Sustained observations in the North Sea reveal the recent onset of oxygen deficiency in late summer, partly due to ocean warming. The intensity and extent of oxygen deficiency has also increased over time. [...]."

Source: Nature 
Authors: Kwangchul Jang et al.
DOI: 10.1038/s43247-023-00708-6

Abstract

"Deep water freshening beneath pan-Arctic ice shelves has recently been proposed based on the absence of excess thorium in glacial Arctic sediments. This profound proposal requires scrutiny of Arctic paleohydrology during past glacial periods. Here, we present structural and geochemical results of inorganic authigenic carbonates in deep-sea glacimarine sediments from the Mendeleev Ridge, western Arctic Ocean over the last 76 kyr. Our results suggest that Polar Deep Water in the western Arctic became brackish and anoxic during stadial periods. We argue that sediment-laden hyperpycnal meltwater discharged from paleo-ice sheets filled much of the water column depending upon the density, substantially reducing the salinity and oxygen content of the Polar Deep Water. [...]."

Source: Nature
Authors: Alexandra Kunert & Brian Kendall
DOI: 10.1038/s41467-023-36516-x

Abstract

"Mesozoic oceanic anoxic events are recognized as widespread deposits of marine organic-rich mudrocks temporally associated with mass extinctions and large igneous province emplacement. The Toarcian Oceanic Anoxic Event is one example during which expanded ocean anoxia is hypothesized in response to environmental perturbations associated with emplacement of the Karoo鈥揊errar igneous province. However, the global extent of total seafloor anoxia and the relative extent of euxinic (anoxic and sulfide-rich) and non-euxinic anoxic conditions during the Toarcian Oceanic Anoxic Event are poorly constrained. [...]."

Source: Science Direct 
Authors: Murat Belivermi艧 et al.
DOI: 10.1016/j.marpolbul.2023.114602

Abstract

"The prevalence and frequency of hypoxia events have increased worldwide over the past decade as a consequence of global climate change and coastal biological oxygen depletions. On the other hand, anthropogenic emissions of CO2 and consequent accumulation in the sea surface result in a perturbation of the seawater carbonate system, including a decrease in pH, known as ocean acidification. While the effect of decreases in pH and dissolved oxygen (DO) concentration is better understood, their combined effects are still poorly resolved. [...]."

Source: Frontiers in Marine Science 
Authors: Wenxia Zhang et al.
DOI: 10.3389/fmars.2023.1146877

Abstract

"Coastal ecosystems play tremendous roles in socio-economic development, but their functions are degrading due to human activities. One of the most alarming degradations is coastal deoxygenation, driven primarily by the over-enrichment of anthropogenic nutrients and organic matter (eutrophication) in the coastal waters. The coastal deoxygenation has led to the worldwide spread of hypoxic zones (where dissolved oxygen concentration is less than 2 mg/L), with the number of reported hypoxic sites increasing from 45 in the 1960s to around 700 nowadays. Besides being perturbed by human activities locally, coastal waters respond more rapidly than the open ocean to global climate change such as ocean warming. [...]."

Source: Springer Nature
Authors: Helen S. Findlay
DOI: 10.1007/978-3-031-10812-9_2

Abstract

"The ocean plays an essential role in regulating Earth鈥檚 climate. The ocean provides many services, but two crucial ones are its ability to take up heat and carbon dioxide (CO₂) from the atmosphere and cycle both around the world in its vast currents, as well as store them away long term. The ocean is changing rapidly and often unnoticed by the general public. However, as the effects of climate change become more prevalent on the ocean, we will start to see a direct impact on human society. This chapter discusses three main climate change effects on the ocean: ocean warming, acidification, and loss of oxygen. [...]."

Source: Science Direct 
Authors: Natascha Ouillon et al.
DOI: 10.1016/j.scitotenv.2022.160459

Abstract

"Benthic species are exposed to oxygen fluctuations that can affect their performance and survival. Physiological effects and ecological consequences of fluctuating oxygen are not well understood in marine bioturbators such as the soft-shell clam Mya arenaria. We explored the effects of different oxygen regimes (21 days of exposure to constant hypoxia (~4.1 kPa PO2), cyclic hypoxia (~2.1鈥搤10.4 kPa PO2) or normoxia (~21 kPa PO2)) on energy metabolism, oxidative stress and ecological behaviors (bioirrigation and bioturbation) of M. arenaria. Constant hypoxia and post-hypoxic recovery in cyclic hypoxia led to oxidative injury of proteins and lipids, respectively. Clams acclimated to constant hypoxia maintained aerobic capacity similar to the normoxic clams. [...]."

"Concepts of resilience and recovery do not only apply to aquatic ecosystems but also to societies when faced with disruptions and crises. Past events have shown that adaptability and decisiveness are important keys to resilience and recovery. Disruptions are opportune moments for setting up strategies for management and recovery. Faced with the COVID-19 pandemic, ASLO meetings have adapted by transforming the ASM 2021 Palma meeting to virtual with a positive attitude that in 2023 we will recover and meet in-person. Positivity is also an important factor.  We do not dwell on problems, but we try to look for solutions and get united for whatever crisis we face.  
We will incorporate the theme of resilience and recovery in aquatic systems into the plenary sessions and encourage submissions that examine these topics and invite you to contribute special sessions on topics relevant to freshwater and marine ecosystems." 

Sessions on ocean oxygen, deoxygenation, anoxia, and hypoxia:

• SS015 Deoxygenation in the Past, Present and Future Ocean
• SS050 Disentangling Complex Long-Term pH and O2 Trends in Coastal and Estuarine Systems From Global and Regional Drivers
• SS107 Oxic-Anoxic Interfaces: Pathways, Dynamics and Exchanges

For further information, please visit the  and . 

"The  webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment 鈥� ocean deoxygenation. Organised and hosted by , each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 21 March 2023 No 19

Moderator:
Andreas Oschlies
黑料视频 Helmholtz Centre for Ocean Research Kiel, Germany

Speakers:
Javier Ar铆stegui
Instituto de Oceanograf铆a y Cambio Global, Universidad de Las Palmas de Gran Canaria, Spain
"Estimating dark-ocean respiration through ETS activity"

Haichao Guo
黑料视频 Helmholtz Centre for Ocean Research Kiel, Germany
"Can oxygen utilization rates track the long-term trend of mesopelagic respiration"

You can watch the GO₂NE Webinar 21 March 2023 No 19 recording . 

Source: Science Direct 
Authors: Javier Fern谩ndez-Mart铆nez et al.
DOI: 10.1016/j.gloplacha.2022.104026

Abstract

"Despite carbon-cycle perturbations at a global scale during the early Toarcian, the extent of anoxia during the 鈭�182-Ma Toarcian Oceanic Anoxic Event (T-OAE) remains in debate. A common factor in the development of oceanic anoxia is watermass restriction, which is thought to have been important in the NW European Seaway, but whose influence elsewhere is relatively unstudied. Here, we analyze Mo/TOC (a proxy for watermass restriction) and redox proxies (e.g., Corg/P) in two sections of the Asturian Basin (northern Iberian Paleomargin), and we integrate these results with data from a suite of global Toarcian sections in order to reassess the relationship of euxinia and local hydrographic restriction during the T-OAE. [...]."

Source: Science Direct 
Authors: Wenlong Pei et al. 
DOI: 10.1016/j.palaeo.2022.111360

Abstract

"Before the Quaternary, the Earth experienced a series of environmental perturbations. The causal links between large volcanic events, extreme climatic change, and ocean anoxia have been examined in the context of these perturbations. However, to date, the correlation between oceanic anoxia and large volcanic activity in the Pleistocene remains poorly constrained. Identifying the physical processes that can control changes to the marine osmium, uranium, and sulfur isotope ratios is critical to understanding how volcanic activity, climate changes, and ocean anoxia have coevolved throughout the Quaternary. [...]."

Source: Science Direct 
Authors: Jun Ma et al. 
DOI: 10.1016/j.marpolbul.2023.114579

Abstract

"The continuous expansion of the oxygen minimum zone (OMZ) is a microcosm of marine hypoxia problem. Based on a survey in M4 seamount area of Tropical Western Pacific Ocean, the effects of thermodynamic parameters on OMZ were discussed. The study showed thermodynamic parameters mainly affect the upper oxycline of OMZ. The increase in temperature aggravates seawater stratification, which not only shallows oxycline but also increases the strength of DO stratification, promoting the expansion of OMZ. [...]."

Source: Science Direct 
Authors: Meredith Burke et al.
DOI: 10.1016/j.csr.2022.104908

Abstract

"Dissolved oxygen (DO) in the global ocean is on the decline, resulting in the degradation of coastal habitats. As aquaculture production occurs in these regions, proper understanding of coastal DO dynamics is important for improved farm management (e.g. site selection). The main objective of this study was to quantify along-shore and cross-shore variability in DO dynamics, as well as onshore advection of offshore waters to the bays that could contain aquaculture farms. [...]."

Source: Cambridge University Press
Authors: Raquel Bryant & Christina L. Belanger
DOI: 10.1017/pab.2022.47

Abstract

"The impact of global climate events on local ecosystems can vary spatially. Understanding this potential heterogeneity can illuminate which environments will be most impacted and the proximal drivers of ecosystem responses. Cenomanian鈥揟uronian marine deposits of the Western Interior Seaway (WIS) record paleoceanographic changes associated with the Greenhorn transgression and the onset of Oceanic Anoxic Event 2 (OAE2). They provide an ideal setting to study basin-wide paleoecological responses during a global perturbation. [...]."

Source: Geological Society of London
Authors: Bryony A. Caswell & Liam Herringshaw
DOI: 10.1144/SP529-2022-226

Abstract

"Climate change is undermining the health and integrity of seafloor ecosystems, with declines in bioturbation expected to impact future ecosystem functioning. We explored changes in the nature and degree of bioturbation during Early Jurassic global warming and ocean deoxygenation. Understanding how these communities responded can help anticipate how bioturbation and ecosystem functioning might change over large spatial and temporal scales. Trace and body fossils from outcrop and core in the Cleveland Basin, UK show how healthy seafloor communities deteriorated through the Pliensbachian spinatum Zone, and macroinfaunal behaviour fluctuated across the Pliensbachian鈥揟oarcian boundary coincident with mass extinction. [...]."

"The  webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment 鈥� ocean deoxygenation. Organised and hosted by , each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 8 February 2023 No 18

Moderator:
Sean Crowe
Departments of Microbiology and Immunology, and Earth, Ocean, and Atmospheric Sciences, The University of British Columbia, Canada

Speakers:
Kohen Bauer
Ocean Networks Canada, University of Victoria, British Columbia, Canada
"Ocean anoxia in deep time: Multiple episodes of rapid ocean deoxygenation during the Cretaceous"

Daniel Mills
Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universit盲t M眉nchen, Munich, Germany
"The control of dissolved O₂ on the diversity of microbial eukaryotes over geologic time"

You can watch the GO₂NE Webinar 8 February 2023 No 18 recording . 

Source: Science Direct 
Authors: Xinze Lu et al. 
DOI: 10.1016/j.gca.2022.11.028

Abstract

"A Tremadocian (Early Ordovician, base Stairsian North American Stage) mass extinction event is recorded globally in rocks from several ancient continents and is accompanied by a globally correlated positive carbon isotope excursion (CIE; the largest during the Early Ordovician). In this study, elemental concentrations and uranium isotope compositions (未238U) were measured for carbonate samples from three sections (along a proximal-to-distal transect: Ibex area, Shingle Pass, Meiklejohn Peak, respectively) in the Great Basin to test the role of ocean anoxia/euxinia on the base Stairsian mass extinction event. [...]."

Source: Science Direct 
Authors: Wei Wei et al.
DOI: 10.1016/j.epsl.2022.117942

Abstract

"Early animals experienced multiple-phase radiations and extinctions from the late Ediacaran to early Cambrian. Oxygen likely played an important role in these evolutionary events, but detailed marine redox evolution during this period remains highly debated. The emerging vanadium (V) isotope system can better capture short-term perturbations to global ocean redox conditions. In this study, we analyzed V isotope compositions (V) of organic-rich cherts and black shales deposited from the late Ediacaran to early Cambrian (ca. 560鈥�518 Ma) in the Yangtze Block, South China. [...]."

Source: Science Direct 
Authors: Yuxin Zhou & Jerry F. McManus
DOI: 10.1016/j.quascirev.2022.107914

Abstract

"Oxygen in the ocean has essential ecological and climatic functions, and can be an important indicator of deep-ocean ventilation and carbon storage. Previous studies are divided on whether the subsurface North Atlantic, which today is well-oxygenated, had higher or lower oxygen levels during the Last Glacial Maximum (LGM). Crucially, the limited number of previous reconstructions precludes any conclusions regarding basin-wide patterns in past changes in oxygenation. [...]."

Source: Science Direct 
Authors: Wenhan Chen et al.
DOI: 10.1016/j.epsl.2022.117959

Abstract

"The late Pliensbachian to early Toarcian was characterized by major climatic and environmental changes, encompassing the early Toarcian Oceanic Anoxic Event (T-OAE, or Jenkyns Event, 鈭�183 Ma) and the preceding Pliensbachian鈥揟oarcian boundary event (Pl/To). Information on seawater redox conditions through this time interval has thus far come mainly from European sections deposited in hydrographically restricted basins, and hence our understanding of the redox evolution of the open ocean (and in particular Panthalassa 鈥� the largest ocean to have existed) is limited. [...]."

Source: Science Direct 
Authors: K. Mareike Paul et al.
DOI: 10.1016/j.chemgeo.2022.121203

Abstract

"Sedimentary molybdenum (Mo) and uranium (U) enrichments are widely used to reconstruct changes in bottom water oxygen conditions in aquatic environments. Until now, most studies using Mo and U have focused on restricted suboxic-euxinic basins and continental margin oxygen minimum zones (OMZs), leaving mildly reducing and oxic (but eutrophic) coastal depositional environments vastly understudied. Currently, it is unknown: (1) to what extent Mo and U enrichment factors (Mo- and U-EFs) can accurately reconstruct oxygen conditions in coastal sites experiencing mild deoxygenation, and (2) to what degree secondary (depositional environmental) factors impact Mo- and U-EFs. [...]."

Source: Science Direct 
Authors: Leticia Maria Cavole et al.
DOI: 10.1016/j.dsr.2022.103941

Abstract

"The deep-sea is rapidly losing oxygen, with profound implications for marine organisms. Within Eastern Boundary Upwelling Systems, such as the California and the Benguela Current Ecosystems, an important question is how the ongoing expansion, intensification and shoaling of Oxygen Minimum Zones (OMZs) will affect deep-sea fishes throughout their lifetimes. One of the first steps to filling this knowledge gap is through the development of tools and techniques to track fishes鈥� exposure to hypoxic (<45 渭mol kg-1), low-temperature (鈭�4鈥�10掳C) and low-pH (鈭�7.5) waters when inhabiting OMZs. [...]."

Source: Nature
Authors: Catherine V. Davis et al.
DOI: 10.1038/s41467-022-35083-x

Abstract

"Oxygen minimum zones (OMZs) play a critical role in global biogeochemical cycling and act as barriers to dispersal for marine organisms. OMZs are currently expanding and intensifying with climate change, however past distributions of OMZs are relatively unknown. Here we present evidence for widespread pelagic OMZs during the Pliocene (5.3-2.6 Ma), the most recent epoch with atmospheric CO2 analogous to modern (~400-450 ppm). The global distribution of OMZ-affiliated planktic foraminifer, Globorotaloides hexagonus, and Earth System and Species Distribution Models show that the Indian Ocean, Eastern Equatorial Pacific, eastern South Pacific, and eastern North Atlantic all supported OMZs in the Pliocene, as today. [...]."