黑料视频

Source: Oxford University Press
Authors: Kathryn L. Howe et al.
DOI: 10.1093/femsec/fiac153

Abstract

"The northern Gulf of Mexico (nGOM) hypoxic zone is a shallow water environment where methane, a potent greenhouse gas, fluxes from sediments to bottom water and remains trapped due to summertime stratification. When the water column is destratified, an active planktonic methanotrophic community could mitigate the efflux of methane, which accumulates to high concentrations, to the atmosphere. To investigate the possibility of such a biofilter in the nGOM hypoxic zone we performed metagenome assembly, and metagenomic and metatranscriptomic read mapping. Methane monooxygenase (pmoA) was an abundant transcript, yet few canonical methanotrophs have been reported in this environment, suggesting a role for non-canonical methanotrophs. [...]."

Source: Nature
Authors: Charl猫ne Feucher et al.
DOI: 10.1038/s43247-022-00570-y

Abstract

"Accurate monitoring of the long-term trend of oxygen content at global scale requires a better knowledge of the regional oxygen variability at interannual to decadal time scale. Here, we combined the Argo dataset and repeated ship-based sections to investigate the drivers of the oxygen variability in the North Atlantic Ocean, a key region for the oxygen supply into the deep ocean. We focus on the Labrador Sea Water in the Irminger Sea over the period 1991鈥�2018 and we show that the oxygen solubility explains less than a third of the oxygen variability. [...]."

"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 December 2022 No 17

Moderator:
Gil Jacinto
Marine Science Institute, University of the Philippines Diliman, Philippines

Speakers:
Lara Sotto
Marine Science Institute, University of the Philippines Diliman, Philippines
"Hypoxia in Manila Bay: Insights from Fieldwork, Nutrient Load and Hydrodynamic Modeling"

Aileen Tan Shau Hwai 
Centre For Marine & Coastal Studies, Universiti Sains Malaysia, Malaysia
"Fish Kills in Malaysia"

You can watch the GO₂NE Webinar 8 December 2022 No 17 recording . 

Source: Nature
Authors: Gabriella D. Kitch et al.
DOI: 10.1038/s43247-022-00641-0

Abstract

"Ocean acidification causes biocalcification stress. The calcium isotope composition of carbonate producers can archive such stress because calcium isotope fractionation is sensitive to precipitation rate. Here, we synthesize morphometric observations of planktic foraminifera with multi-archive calcium isotope records from Gubbio, Italy and the Western Interior Seaway spanning Cretaceous Ocean Anoxic Event 2 (~94 million years ago). Calcium isotope ratios increase ~60 thousand years prior to the event. [...]."

Source: Wiley Online Library
Authors: Kohen W. Bauer et al.
DOI: 10.1111/gbi.12538

Abstract

"Oceanic Anoxic Events (OAEs) are conspicuous intervals in the geologic record that are associated with the deposition of organic carbon (OC)-rich marine sediment, linked to extreme biogeochemical perturbations, and characterized by widespread ocean deoxygenation. Mechanistic links between the marine biological carbon pump (BCP), redox conditions, and organic carbon burial during OAEs, however, remain poorly constrained. In this work we reconstructed the BCP in the western Tethys Ocean across OAE1a (~120 Mya) using sediment geochemistry and OC mass accumulation rates (OCAcc). [...]."

Source: Taylor & Francis Online
Authors: Annaliese C.S. Meyer et al. 
DOI: 10.1080/07055900.2022.2153325

Abstract

"This study presents dissolved nitrous oxide (N2O) concentrations in the water column at the Bermuda Atlantic Time-series Study (BATS) station and uses a subset of these measurements to estimate air-to-sea flux for four specific time points between September 2018 and June 2019. N2O concentrations at BATS were in the range of 4.0 nmol L鈭�1鈥�16.9 nmol L鈭�1, with vertical profiles which were the mirror inverse of dissolved oxygen. Regardless of season, N2O concentration maxima were found within the oxygen minimum zone (OMZ). The highest maximum N2O values were observed in November and lowest in October. [...]."

Source: Nature
Authors: Ute Daewel et al.
DOI: 10.1038/s43247-022-00625-0 

Abstract

"The wind wake effect of offshore wind farms affects the hydrodynamical conditions in the ocean, which has been hypothesized to impact marine primary production. So far only little is known about the ecosystem response to wind wakes under the premisses of large offshore wind farm clusters. Here we show, via numerical modeling, that the associated wind wakes in the North Sea provoke large-scale changes in annual primary production with local changes of up to 卤10% not only at the offshore wind farm clusters, but also distributed over a wider region. [...]."

Source: Nature
Authors: Karin Kvale & Andreas Oschlies
DOI: 10.1038/s41561-022-01096-w 

Abstract

"Climate change and plastics pollution are dual threats to marine environments. Here we use biogeochemical and microplastic modelling to show that even if there is complete removal of microplastics and cessation of deposition in the oceans in 2022, regional recovery from microplastic-induced remineralization and water column deoxygenation could take hundreds of years for coastal upwelling zones, the North Pacific and Southern Ocean. [...]."

Source: Nature
Authors: Nicolaas Glock et al. 
DOI: 10.1038/s43247-022-00635-y 

Abstract

"Quantifying past oxygen concentrations in oceans is crucial to improving understanding of current global ocean deoxygenation. Here, we use a record of pore density of the epibenthic foraminifer Planulina limbata from the Peruvian Oxygen Minimum Zone to reconstruct oxygen concentrations in bottom waters from the Last Glacial Maximum to the Late Holocene at 17.5掳S about 500 meters below the sea surface. We found that oxygen levels were 40% lower during the Last Glacial Maximum than during the Late Holocene (about 6.7 versus 11.1 碌mol/kg, respectively). [...]."

Source: Wiley Online Library
Authors: Julius J.M. Busecke et al.
DOI: 10.1029/2021AV000470

Abstract

"Global ocean oxygen loss is projected to persist in the future, but Earth system models (ESMs) have not yet provided a consistent picture of how it will influence the largest oxygen minimum zone (OMZ) in the tropical Pacific. We examine the change in the Pacific OMZ volume in an ensemble of ESMs from the CMIP6 archive, considering a broad range of oxygen (O2) thresholds relevant to biogeochemical cycles and ecosystems (5鈥�160 碌mol/kg). Despite OMZ biases in the historical period of the simulations, the ESM ensemble projections consistently fall into three regimes across ESMs: an expansion of low oxygenated waters (+0.8 [0.6, 1.0] 脳 1016 m3/century for O2 鈮� 120 碌mol/kg, ESM median and interquartile range); a slight contraction of the OMZ core although more uncertain across ESMs (鈭�0.1 [鈭�0.5, 0.0] 脳 1016 m3/century for O2 鈮� 20 碌mol/kg); and at the transition from contraction to expansion regimes, a spatial redistribution but near-zero change in the volume of hypoxic waters (0.0 [鈭�0.3, +0.1] 脳 1016 m3/century for O2 鈮� 60 碌mol/kg). [鈥�]."

Source: Wiley Online Library
Authors: Lillian R. McCormick et al.
DOI: 10.1002/lol2.10296

Abstract

"Changing oxygen conditions are altering the distribution of many marine animals. Zooplankton vertical distributions are primarily attributed to physiological tolerance and/or avoidance of visual predation. Recent findings reveal that visual function in marine larvae is highly sensitive to oxygen availability, but it is unknown how oxygen, which affects light sensitivity and generates limits for vision, may affect the distribution of animals that rely heavily on this sensory modality. This study introduces the concept of a 鈥渧isual luminoxyscape鈥� to demonstrate how combinations of limiting oxygen and light could constrain the habitat of marine larvae with oxygen-demanding vision. [...]."

Source: Science Direct 
Authors: Yu Zhang et al.
DOI: 10.1016/j.marpetgeo.2022.105958

Abstract

"The evolution of global ocean oxygenation during the early Cambrian remains highly controversial, making it difficult to evaluate how environmental triggers play a role in controlling the organic matter (OM) accumulation in black shales. In this study, an integrated approach, including total organic carbon (TOC) content, major and trace element geochemistry, and microscope images, was systematically conducted in a continuous core well that penetrated through the Lower Cambrian Yanjiahe (YJH)鈥揝huijingtuo (SJT, subdivided into SM 鈪�, SM 鈪�, SM 鈪�, and SM 鈪� members) successions (鈭�541-514Ma) at the Three Gorges area [...]."

Source: Nature
Authors: Jianghui Du et al.
DOI: 10.1038/s41586-022-05267-y

Abstract

"North Pacific deoxygenation events during the last deglaciation were sustained over millennia by high export productivity, but the triggering mechanisms and their links to deglacial warming remain uncertain. Here we find that initial deoxygenation in the North Pacific immediately after the Cordilleran ice sheet (CIS) retreat was associated with increased volcanic ash in seafloor sediments. Timing of volcanic inputs relative to CIS retreat suggests that regional explosive volcanism was initiated by ice unloading. [鈥�]."

Source: Science Direct 
Authors: Junpeng Zhang et al.
DOI: 10.1016/j.epsl.2022.117858

Abstract

"The Great Ordovician Biodiversification Event (GOBE) achieved its peak during the Middle Ordovician, likely in association with climatic cooling and a rise of atmospheric O2. However, unstable redox states developed widely in contemporaneous epeiric seas, challenging previous assumptions about sustained oceanic oxygenation driven by deep-ocean ventilation in the aftermath of Ordovician cooling. Here, we investigate two Middle-Upper Ordovician shale-dominated successions from intra-shelf basin and slope settings of the Yangtze Sea, South China. [鈥�]."

Source: Science Direct
Authors: Yuzhu Ge & David P.G. Bond
DOI: 10.1016/j.earscirev.2022.104220

Abstract

"Marine redox conditions through the Permian-Triassic (P-T) boundary interval have been intensively studied in South China with different redox proxies and from different sections. However, the resultant interpretations are inconsistent and sometimes even controversial, thereby impeding an overall understanding of global environmental changes and of causes for the P-T mass extinction events. This study summarizes and reevaluates these previous studies. [...]."

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 second issue of GOOD News, you can read more about:

• GO2NE online meeting 鈥� October 2022
• EBUS Conference 鈥� Lima, Peru September 2022
• Side event at the UNFCCC COP27 calling on the integration of ocean deoxygenation in climate action
• Ocean deoxygenation and acidification Summer School
• GO2NE webinar series
• Events, announcements, and opportunities 

Source: Springer Link
Authors: Karlina Triana et al.
DOI: 10.1007/s10661-022-10615-6

Abstract

"Deoxygenation is increasingly recognized as a significant environmental threat to the ocean following sea temperature rises due to global warming and climate change. Considering the cruciality of the deoxygenation impacts, it is important to assess the current status and predict the future possibility of ocean deoxygenation, for instance, within the Central Indo Pacific (CIP) regions represent climate-regulated marine areas. This study divided CIP into five regions then investigated the deoxygenation parameters (dissolved oxygen, temperature, salinity, and pH) collected from 1993 to 2021 sourced from in situ measurement and long-term hindcast data. [...]."

Source: Nature
Authors: Samuel A. H. Kekuewa et al. 
DOI: 10.1038/s41598-022-21831-y

Abstract

"The California Current System experiences seasonal ocean acidification and hypoxia (OAH) owing to wind-driven upwelling, but little is known about the intensity, frequency, and depth distribution of OAH in the shallow nearshore environment. Here we present observations of OAH and dissolved inorganic carbon and nutrient parameters based on monthly transects from March 2017 to September 2018 extending from the surf zone to the鈥墌鈥�40 m depth contour in La Jolla, California. Biologically concerning OAH conditions were observed at depths as shallow as 10 m and as close as 700 m to the shoreline. [...]."

Source: Wiley Online Library  
Authors: Steven Emerson & Bo Yang
DOI: 10.1029/2022GL099834

Abstract

"The magnitude and distribution of the ocean's biological pump (the downward flux of organic carbon (OC) from the ocean surface) influences the pCO2 of the atmosphere and the O2 content of the deep sea, but has not been well quantified. We determine this flux in the ocean's five subtropical gyres using upper-ocean oxygen mass balance and measurements of T, S, and pO2 by autonomous profiling floats. Our results suggest that the biological OC pump is not globally uniform among the subtropical gyres: values in the North Pacific and Atlantic indicate distinct autotrophy (1鈥�2 mol C m鈭�2 yr鈭�1) while near zero values in the S. [...]."

Source: Science Direct 
Authors: Zaitian Zhang et al.
DOI: 10.1016/j.gloplacha.2022.103942

Abstract

"The Carnian Humid Episode (CHE) represents a dramatic dry to wet climate transition in the Late Triassic. Manifestations of this climate shift and its associated biological and environmental responses are not fully understood. Here, we carried out carbonate carbon isotope, trace metal, and pyrite framboid analyses at Wolonggang in southwest China to trace palaeoenvironmental changes during this critical interval. The CHE at Wolonggang is marked by the development of fine laminated carbonaceous siltstones and black shales overlying the intensely bioturbated Zhuganpo limestone deposited in the latest Julian 1. [...]."

Source: Science Direct 
Authors: Edson Piscoya et al.
DOI: 10.1016/j.marenvres.2022.105710

Abstract

"The vertical distribution of phytoplankton is of fundamental importance in the structure, dynamic, and biogeochemical pathways in marine ecosystems. Nevertheless, what are the main factors determining this distribution remains as an open question. Here, we evaluated the relative influence of environmental factors that might control the coexistence and vertical distribution of pico-nanoplankton associated with the OMZ off northern Chile. Our results showed that in the upper layer Synechococcus-like cells were numerically important at all sampling stations. [...]."

Source: Science Direct 
Authors: Yusuke Kuwahara et al. 
DOI: 10.1016/j.gloplacha.2022.103920

Abstract

"The Late Devonian, during which one of the 鈥淏ig Five鈥� Phanerozoic mass extinction events occurred, was one of the most important time intervals in Earth history. Nevertheless, the paucity of deep-sea records due to subduction has hampered elucidation of the pelagic environment during the Late Devonian in Panthalassa. However, ancient hydrothermal ferromanganese sediments, which were deposited on the abyssal seafloor and then accreted onto continental margins, are preserved as umber deposits and exposed in accretionary prisms. These sediments can provide key information to characterize the paleo-ocean. [...]."

Source: Nature
Authors: Katrin J. Meissner & Andreas Oschlies
DOI: 10.1038/d41586-022-02187-9

Abstract

"Variations in ocean oxygen levels during Earth鈥檚 history have been linked to evolution and mass extinctions. Simulations now suggest that the configuration of the continents has a substantial impact on ocean oxygenation. [...]."

Source: Science Direct 
Authors: Wen-qian Wang et al.
DOI: 10.1016/j.epsl.2022.117714

Abstract

"The redox chemistry change in ancient oceans has profoundly shaped the evolutionary trajectories of animals. Uranium isotopes (U) in marine carbonate sediments have widely been used to place quantitative constraints on the oxygenation state of the oceans through geological history. However, syndepositional and post-depositional diagenesis impose a positive and variable U offset in the carbonate sediments relative to contemporaneous seawater, leaving uncertainties on quantification of anoxic seafloor areas in the past. Studies from modern settings suggest that Low-Magnesium Calcite (LMC) in articulate brachiopod shells are diagenetic resistant materials that may faithfully record the U value of ancient seawater. [...]."

Source: Science Direct 
Authors: Thomas Steuber et al.
DOI: 10.1016/j.palaeo.2022.111086

Abstract

"We report the first high-resolution sedimentological and geochemical record of the negative carbon-isotope excursion (CIE) at the onset of the early Aptian oceanic anoxic event (OAE) 1a from a carbonate-ramp depositional environment, analysed from a well core from c. 2500 m depth, 100 km offshore Abu Dhabi, United Arab Emirates. Time-series analysis of stable oxygen isotope values and concentrations of Si, Al, and Ti resulted in durations of the C3 and C4 segments of the CIE that support relative completeness of the C3 segment and high sediment preservation rates of c. 13 cm/kyr of the studied sedimentary sequence. [...]."

"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 October 2022 No 16

Moderator:
Grant Pitcher
Department of Forestry, Fisheries and the Environment, South Africa

Speakers:
Annette Carlson
University of Connecticut, USA
"Assessing drivers of oxygen dynamics in the southern Benguela Upwelling System through the combined application of models and observations"

Bronwyn Currie
Namibian Ministry of Fisheries and Marine Resources, Namibia
"Oxygen calls the shots in the Northern Benguela Upwelling System off Namibia"

You can watch the GO₂NE Webinar 20 October 2022 No 16 recording . 

Source: Wiley Online Library  
Authors: Michael A. Kipp
DOI: 10.1029/2022GL099817

Abstract

"Modern anoxic marine sediments release phosphorus (P) to seawater, driving feedbacks at multiple timescales. On sub-Myr timescales, anoxic P regeneration amplifies ocean deoxygenation; on multi-Myr timescales, it stabilizes atmospheric O2. Some authors have extended this thinking to the Precambrian: by analogy, widespread ocean anoxia would imply extensive P regeneration from sediments. However, this neglects the role of sulfate in P regeneration. [...]."

Source: Wiley Online Library  
Authors: Pengfei Xue et al.
DOI: 10.1029/2022JB024714

Abstract

"The Paleocene-Eocene Thermal Maximum (PETM, 鈭�56 Ma) presents a past analog for future global warming. Previous studies provided evidence for major loss of dissolved oxygen during the PETM, although understanding the degree and distribution of oxygen loss poses challenges. Magnetofossils produced by magnetotactic bacteria are sensitive to redox conditions in sediments and water columns, and have been used to reconstruct paleoredox conditions over a range of geological settings. [...]."

Source: Nature 
Authors: Katja Fennel et al.
DOI: 10.1038/s43586-022-00154-2 

Abstract

"Ocean biogeochemical models describe the ocean鈥檚 circulation, physical properties, biogeochemical properties and their transformations using coupled differential equations. Numerically approximating these equations enables simulation of the dynamic evolution of the ocean state in realistic global or regional spatial domains, across time spans from years to centuries. This Primer explains the process of model construction and the main characteristics, advantages and drawbacks of different model types, from the simplest nutrient鈥損hytoplankton鈥搝ooplankton鈥揹etritus model to the complex biogeochemical models used in Earth system modelling and climate prediction. [...]."

Source: Wiley Online Library  
Authors: Ana C. Franco et al.
DOI: 10.1111/fog.12610

Abstract

"Ocean warming and deoxygenation are already modifying the habitats of many aerobic organisms. Benthic habitat in the Northeast Pacific is sensitive to deoxygenation, as low oxygen concentrations occur naturally in continental shelf bottom waters. Here, we examine the potential impacts of deoxygenation and ocean warming on the habitat distribution of Pacific halibut (Hippoglossus stenolepis), one of the most commercially important groundfish in North America. [...]."

Source: Wiley Online Library
Authors: Anta-Clarisse Sarr et al.
DOI: 10.1029/2022GL099830

Abstract

"Mechanisms that drive cyclicity in marine sediment deposits during hothouse climate periods in response to Earth鈥檚 orbit variations remain debated. Orbital cycles fingerprint in the oceanographic records results from the combined effect of terrestrial (e.g. weathering-derived nutrient supply, freshwater discharge) and oceanic (e.g. productivity, oxygenation) processes, whose respective contribution remains to be clarified. [...]."

Source: Science Direct 
Authors: Alberto S谩nchez et al.
DOI: 10.1016/j.dsr.2022.103810

Abstract

"The expansion of the oxygen minimum zone (OMZ) associated with global warming has generated interest in its variability during the last two millennia. Several oceanographic mechanisms, as advection of dissolved oxygen and depletion of dissolved oxygen by oxidation of exported marine productivity, could explain the variability of 未15N in organic matter as a denitrification indicator of the water column in the Pacific Ocean. Our objective was to infer local or remote forcing mechanisms that lead to the strengthening or weakening of the OMZ in the Eastern Tropical North Pacific. [...]."

Source: Science Direct 
Authors: Edward J. Matheson et al.
DOI: 10.1016/j.epsl.2022.117715

Abstract

"Marine ironstone is a Phanerozoic biochemical sedimentary rock that contains abundant primary iron. Although rare, ironstone is conspicuous in the Paleozoic sedimentary record. Its iron source remains contentious, with traditional models invoking a continentally derived source. Increasing sedimentologic evidence suggests that many Paleozoic ironstones formed along favourably oriented continental margins where coastal upwelling delivered ferruginous waters, with the postulated source of iron being deep-ocean hydrothermal fluids. [...]."

Source: Science Direct 
Authors: Lucien Nana Yobo et al.
DOI: 10.1016/j.gca.2022.06.016

Abstract

"Chromium is a redox sensitive element that exhibits a large range of isotopic compositions in Earth鈥檚 surface environments because of Cr(VI)-Cr(III) transformations. This property of Cr has been exploited as a tracer of Earth鈥檚 oxygenation history using marine sediments. However, paleoredox applications using Cr are difficult to implement due to its complicated cycling, which creates spatial variability in seawater 未53Cr values. Applications are further hindered by the potential for variability in the major inputs of Cr, such as submarine volcanism, to mask redox processes. [...]."

Source: Nature
Authors: Alexandre Pohl et al.
DOI: 10.1038/s41586-022-05018-z 

Abstract

"The early evolutionary and much of the extinction history of marine animals is thought to be driven by changes in dissolved oxygen concentrations ([O2]) in the ocean. In turn, [O2] is widely assumed to be dominated by the geological history of atmospheric oxygen (pO2). Here, by contrast, we show by means of a series of Earth system model experiments how continental rearrangement during the Phanerozoic Eon drives profound variations in ocean oxygenation and induces a fundamental decoupling in time between upper-ocean and benthic [O2]. [...]."

Source: Wiley Online Library
Authors: Yi Ding et al.
DOI: 10.1111/gbi.12520

Abstract

"Most previous studies focused on the redox state of the deep water, leading to an incomplete understanding of the spatiotemporal evolution of the redox-stratified ocean during the Ediacaran鈥揅ambrian transition. In order to decode the redox condition of shallow marine environments during the late Ediacaran, this study presents I/(Ca鈥�+鈥塎g), carbon and oxygen isotope, major, trace, and rare earth element data of subtidal to peritidal dolomite from the Dengying Formation at Yangba, South China. [...]."

Source: Science Direct 
Authors: Wenhan Chen et al.
DOI: 10.1016/j.gloplacha.2022.103884

Abstract

"The early Toarcian Oceanic Anoxic Event (T-OAE, ~183 Ma) was characterized by marine deoxygenation and the burial of organic-rich sediments at numerous localities worldwide. However, the extent of marine anoxia and its impact on the sulfurcycle during the T-OAE is currently poorly understood. Here, stable sulfur isotopes of reduced metal-bound sulfur (未34Spyrite) and pyrite sulfur concentrations (SPY) have been analyzed across the Pliensbachian-Toarcian boundary (Pl-To) and the T-OAE from the Sakahogi and Sakuraguchi-dani sections (Japan), which were deposited in the deep and shallow Panthalassic Ocean, respectively. [...]."

Source: Wiley Online Library 
Authors: Mark Holzer
DOI: 10.1029/2022JC018802

Abstract

"We investigate the sensitivity of the oxygen content and true oxygen utilization of key low-oxygen regions 惟 to pointwise changes in biological production. To understand how the combined water and biogenic particle transport controls the sensitivity patterns and the fate of oxygen in the ocean, we develop new relationships that link the steady-state oxygen content and deficit of 惟 to the downstream and upstream oxygen utilization rate (OUR), respectively. We find that the amount of oxygen from 惟 that will be lost per unit volume at point r is linked to OUR(r) through the mean oxygen age accumulated in 惟. [...]."

Source: Science Direct 
Authors: Zhi-Hui Zhang et al.
DOI: 10.1016/j.jop.2022.06.002

Abstract

"The Cretaceous has been considered a 鈥渉igh-fire鈥� world accompanied by widespread by-products of combustion in the rock record. The mid-Cretaceous oceanic anoxic event 1b (OAE1b) is marked by one of the major perturbations in the global carbon cycle characterized by deposition of organic-rich sediments in both marine and terrestrial settings. However, our understanding is still limited on changes in wildfire activity during OAE1b period. [...]."

Source: Science Direct 
Authors: Edel Mary O'Sullivan et al.
DOI: 10.1016/j.precamres.2022.106760

Abstract

"This study addresses marine palaeoredox conditions of the mid-Neoproterozoic by analysing the Mo isotope, trace element, and U-Th-Pb isotope compositions of shallow water microbial carbonate, deep water pelagic carbonate, and shale from the Stone Knife Formation (SKF) in NW Canada. The U-Th-Pb isotope SKF systematics of reef microbialite carbonates, and the moderately expressed negative Ce anomalies are consistent with the presence of dissolved O2 in the surface waters. [...]."

Source: Science Direct 
Authors: Guangyou Zhu et al.
DOI: 10.1016/j.chemgeo.2022.120929

Abstract

"The Cryogenian interglacial period have witnessed dramatic changes in climate, oceanic environment and biological evolution. The nitrogen isotopic composition, as an important biogeochemical proxy, has the potential to track both the nutrient cycling and redox conditions in the past. However, nitrogen isotopic data during this interglacial time is rather limited. Here, we present integrated data for nitrogen isotopes (未15N), as well as organic carbon isotopes (未13Corg), iron (Fe) speciation, pyrite morphology and trace elements from the Cryogenian interglacial Datangpo Formation derived from a drill core from South China to figure out the nitrogen cycling and coeval redox states. [...]."

Source: Science Direct 
Authors: Hanwei Yao et al.
DOI: 10.1016/j.gloplacha.2022.103881

Abstract

"The Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE 2, ca. 94 Ma) was one of the most extreme carbon cycle and climatic perturbations of the Phanerozoic Eon. Widespread deposition of organic-rich shales during OAE 2 has been attributed to a rapid rise in atmospheric CO2, global heating, and marine anoxia triggered by intense large igneous province (LIP) volcanism. Here, we present new Hg and Zn elemental and isotopic analyses from samples spanning OAE 2 in a hemipelagic section from Rehkogelgraben, Austria, which was part of the north-western Tethys. [...]."

Source: Science Direct 
Authors: Brayden S. McDonald et al.
DOI: 10.1016/j.gca.2022.05.010

Abstract

"A 未238U record of changing ocean anoxia during OAE 2 is reconstructed using seawater derived U in pelagic marine sediments in the Portland #1 core in the south-central region of the Western Interior Seaway of North America. The peak negative excursion of 1.4鈥� in authigenic sedimentary 未238U values is consistent with expansion of marine anoxia during the event, but the size of the shift is much larger than the negative excursions recorded in two other published records. [...]."

Source: Science Direct 
Authors: Zhong Han et al.
DOI: 10.1016/j.gloplacha.2022.103887

Abstract

"The early Toarcian, as registered in a variety of sedimentary archives, was characterized by an abrupt negative carbon-isotope excursion (CIE) typically superimposed on a long-term positive trend, and was accompanied by significant climatic and environmental changes. However, the changes in continental weathering influx and oceanic deoxygenation in shallow waters and their possible role in causing carbonate-platform crises in low latitudes remains poorly constrained. [...]."

Source: Wiley Online Library 
Authors: Jamie Atkins et al.
DOI: 10.1029/2022GL098672

Abstract

"Ocean mesoscale eddies have been identified as drivers of localized extremely low dissolved oxygen concentration ([O2]) conditions in the subsurface. We employ a global physical-biogeochemical ocean model at eddy-permitting resolution to conduct a census of open-ocean eddies near Eastern Boundary Upwelling Systems adjacent to tropical Oxygen Minimum Zones (OMZs). We track cyclonic and anticyclonic eddies with a surface signature over the period 1992鈥�2018 and isolate their subsurface oxygen characteristics. We identify strongly deoxygenating eddies and quantify their contribution to low [O2] extreme events. [...]."

Source: Science Direct 
Authors: Ga毛l Le Croizier et al.
DOI: 10.1016/j.marpolbul.2022.113892

Abstract

"Oxygen minimum zones (OMZs) are currently expanding across the global ocean due to climate change, leading to a compression of usable habitat for several marine species. Mercury stable isotope compositions provide a spatially and temporally integrated view of marine predator foraging habitat and its variability with environmental conditions. Here, we analyzed mercury isotopes in blue sharks Prionace glauca from normoxic waters in the northeastern Atlantic and from the world's largest and shallowest OMZ, located in the northeastern Pacific (NEP). [...]."

Source: Science Direct 
Authors: Wei Shi et al.
DOI: 10.1016/j.epsl.2022.117619

Abstract

"The Ediacaran Period (鈭�635 to 541 Ma) witnessed the early diversification and radiation of metazoans, in the form of the Ediacaran Biota. This biological revolution, beginning at 鈭�575 Ma, has been widely attributed to a temporally restricted episode of deeper ocean oxygenation, potentially caused by a contemporaneous rise in atmospheric oxygen levels. However, quantitative geochemical-record-driven estimates of Ediacaran atmospheric and oceanic redox evolution are lacking, and hence possible links between oceanic and atmospheric oxygenation remain speculative. [...]."

"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 23 August 2022 No 15

Moderator:
Jodie Rummer
James Cook University, Australia

Speakers:
Ariel Pezner
Scripps Institution of Oceanography, University of California San Diego, USA
"Coral reef hypoxia: Present-day exposure and projections under warming"

David Suggett
University of Technology Sydney, Australia
"Unlocking the vulnerability of reef-forming corals to deoxygenation"

You can watch the GO₂NE Webinar 23 August 2022 No 15 recording . 

Source: Science Direct 
Authors: Vidhya Vijayasenan et al.
DOI: 10.1016/j.pocean.2022.102839

Abstract

"The Arabian Sea and the Bay of Bengal are cul-de-sacs of the northern Indian Ocean, and they contain more than half of the world's Oxygen Minimum Zones (OMZs). The current study reviews the vast and advancing literature on the oceanographic settings that lead to distinct OMZs in the Arabian Sea and the Bay of Bengal and links them with the copepods thriving there, their status, and likely adaptations. The Arabian Sea has a thicker perennial subsurface OMZ (鈭�1000 m) than the Bay of Bengal (鈭�500 m), which is linked to high plankton production via upwelling and winter convection in the former and river influx and mesoscale eddies in the latter. [...]."

Source: Taylor & Francis Online
Authors: Ujwala Amberkar & Rakhee Khandeparker 
DOI: 10.1080/17451000.2022.2086700

Abstract

"The Arabian Sea (AS) oxygen minimum zone (OMZ) is a site of intense denitrification, contributing to 20% of the global oceanic denitrification, playing a significant role in the nitrogen cycle. In this study, the structure and diversity of culturable bacterial communities inhabiting the water column of the AS OMZ were investigated through phylogenetic analysis and nitrate-utilizing ability was studied through culture-based studies. A total of 248 isolates collected during pre-monsoon and post-monsoon season were analysed for 16S rRNA gene sequences. [...]."

Source: Science Direct 
Authors: Xiao Chen et al.
DOI: 10.1016/j.watres.2022.118690

Abstract

"Ocean deoxygenation could potentially trigger substantial changes in the composition and reactivity of dissolved organic matter (DOM) pool, which plays an important role in the global carbon cycle. To evaluate links between DOM dynamics and oxygen availability, we investigated the DOM composition under varying levels of oxygen in a seasonally hypoxic fjord through a monthly time-series over two years. We used ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to characterize DOM on a molecular level. [...]."

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 first issue of GOOD News, you can read more about:

• The Global Ocean Oxygen Network (GO2NE) and the Global Ocean Oxygen Decade (GOOD)
• Call for Nominations for new members of the Global Ocean Oxygen Network committee
• GO2DAT Hackathon 2022
• Li猫ge Colloquium 鈥� May 2022
• Arctic cruise on icebreaker 鈥淟e Commandant Charcot鈥�, 3 June 鈥� 8 July 2022
• GO2NE webinar series
• Events, announcements, and opportunities

Source: Science  
Authors: Nina M. Papadomanolaki et al.
DOI: 10.1126/sciadv.abn2370

Abstract

"Enhanced recycling of phosphorus as ocean deoxygenation expanded under past greenhouse climates contributed to widespread organic carbon burial and drawdown of atmospheric CO2. Redox-dependent phosphorus recycling was more efficient in such ancient anoxic marine environments, compared to modern anoxic settings, for reasons that remain unclear. Here, we show that low rates of apatite authigenesis in organic-rich sediments can explain the amplified phosphorus recycling in ancient settings as reflected in highly elevated ratios of organic carbon to total phosphorus. [...]."

"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 July 2022 No 14

Moderator:
Moriaki Yasuhara
The University of Hong Kong

Speakers:
Huai-Hsuan May Huang
National Museum of Natural History, Smithsonian Institution, USA
"Reconstructing biotic responses to deoxygenation in the geological past based on microfossils"

Curtis Deutsch
Princeton University, USA
"Metabolic Index predicts the Temperature Size Rule"

You can watch the GO₂NE Webinar 13 July 2022 No 14 recording . 

Source: Science 
Authors: Akitomo Yamamoto et al. 
DOI: 10.1126/sciadv.abl9207

Abstract

"Nutrient inputs from the atmosphere and rivers to the ocean are increased substantially by human activities. However, the effects of increased nutrient inputs are not included in the widely used CMIP5 Earth system models, which introduce bias into model simulations of ocean biogeochemistry. Here, using historical simulations by an Earth system model with perturbed atmospheric and riverine nutrient inputs, we show that the contribution of anthropogenic nutrient inputs to past global changes in ocean biogeochemistry is of similar magnitude to the effect of climate change. [...]."

Source: Wiley Online Library 
Authors: Daniel A. Stolper et al. 
DOI: 10.1029/2021GC010196

Abstract

"The deep ocean is generally considered to have changed from anoxic in the Precambrian to oxygenated by the Late Paleozoic (鈭�420鈥�400 Ma) due to changes in atmospheric oxygen concentrations. When the transition occurred, that is, in the Early Paleozoic or not until the Late Paleozoic, is less well constrained. To address this, we measured Fe3+/危Fe of volcanic rocks, sheeted dykes, gabbros, and ultramafic rocks from the Early Paleozoic (鈭�485 Ma) Bay of Islands (BOI) ophiolite as a proxy for hydrothermal alteration in the presence or absence of O2 derived from deep marine fluids. [...]."

Source: Nature
Authors: Catherine V. Davis
DOI: 10.1038/s43247-022-00477-8

Abstract

"Oxygenation in the Eastern Equatorial Pacific is responsive to ongoing climate change in the modern ocean, although whether the region saw a deglacial change in extent or position of the Oxygen Minimum Zone remains poorly constrained. Here, stable isotopes from the shells of an Oxygen Minimum Zone-dwelling planktic foraminifer are used to reassess the position of the mid-water Oxygen Minimum Zone relative to both the thermocline and benthos. Oxygen isotopes record a rapid shoaling of the Oxygen Minimum Zone towards the thermocline associated with Heinrich Stadial 1 and persisting through the deglaciation. [...]."

Source: Science Direct 
Authors: Lei Zhang et al.
DOI: 10.1016/j.gloplacha.2022.103798

Abstract

"Microbe-metazoan transitions (MMTs), representing a switch from microbe-mediated to metazoan-mediated carbonate production, have been linked to major changes in Earth-surface conditions. The 鈥榣ate Cambrian MMT鈥� (nomen novum), during which microbial reefs were replaced by maceriate and lithistid sponge reefs, coincided with a sharp rise in atmospheric O2 levels attributed to the Steptoean Positive Carbon Isotope Excursion (SPICE) at ~497鈥�494 Ma. However, relationships between atmospheric oxygenation, marine redox conditions, and the MMT have not been thoroughly investigated to date. [...]."

Source: ASM Journals
Authors: Bowei Gu et al. 
DOI: 10.1128/spectrum.00892-21

Abstract

"Ocean oxygen minimum zones (OMZs) around the global ocean are expanding both horizontally and vertically. Multiple studies have identified the significant influence of anoxic conditions (鈮�1鈥壩糓 O2) on marine prokaryotic communities and biogeochemical cycling of elements. However, little attention has been paid to the expanding low-oxygen zones where the oxygen level is still above the anoxic level. Here, we studied the abundance and taxonomic and functional profiles of prokaryotic communities in the Bay of Bengal (BoB), where the oxygen concentration is barely above suboxic level (5鈥壩糓 O2). [...]."

Source: Science Direct 
Authors: J. Jeffrey Morris et al.
DOI: 10.1016/j.redox.2022.102285

Abstract

"Reactive oxygen species (ROS) are omnipresent in the ocean, originating from both biological (e.g., unbalanced metabolism or stress) and non-biological processes (e.g. photooxidation of colored dissolved organic matter). ROS can directly affect the growth of marine organisms, and can also influence marine biogeochemistry, thus indirectly impacting the availability of nutrients and food sources. Microbial communities and evolution are shaped by marine ROS, and in turn microorganisms influence steady-state ROS concentrations by acting as the predominant sink for marine ROS. [...]."

Source: Science Direct 
Authors: Carlos A. Alvarez Zarikian et al.
DOI: 10.1016/j.marmicro.2022.102105

Abstract

"We present the first continuous middle through late Pleistocene record of fossil ostracods from the Maldives in the northern Indian Ocean, derived from sediment cores taken at Site U1467 by Expedition 359 of the International Ocean Discovery Program (IODP). Site U1467 lies at 487 m water depth in the Inner Sea of the Maldives archipelago, an ideal place for studying the effects of the South Asian Monsoon (SAM) system on primary productivity, intermediate depth ocean circulation, and the regional oxygen minimum zone (OMZ). [...]."

Source: Nature 
Authors: Gregory T. Connock et al. 
DOI: 10.1038/s43247-022-00466-x 

Abstract

"Understanding the causal mechanisms of past marine deoxygenation is critical to predicting the long-term Earth systems response to climate change. However, the processes and events preceding widespread carbon burial coincident with oceanic anoxic events remain poorly constrained. Here, we report a comprehensive biomarker inventory enveloping Oceanic Anoxic Event 2 that captures microbial communities spanning epipelagic to benthic environments in the southern proto-North Atlantic Ocean. We identify an abrupt, sustained increase in primary productivity that predates Oceanic Anoxic Event 2 by 鈭�220鈥壜扁��4 thousand years, well before other geochemical proxies register biogeochemical perturbations. [...]."

Source: Science Direct 
Authors: Mu Liu et al.
DOI: 10.1016/j.epsl.2022.117553

Abstract

"The Late Ordovician (Hirnantian) mass extinction (LOME) was marked by two discrete pulses of high species turnover rates attributed to glacial cooling (LOME-1) and subsequent expansion of anoxic marine conditions (LOME-2). However, the mechanisms and extent of global marine anoxia remain controversial. In this study, we present uranium isotope (U) data from a new Ordovician-Silurian (O-S) boundary carbonate section in the Southwest China to explore the extent/duration of the global marine anoxia, and links to the LOME. [...]."

"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 June 2022 No 13

Moderator:
Guizhi Wang 
Xiamen University, China

Speakers:
Yangyang Zhao
Xiamen University, China
"Interactive hypoxia-acidification in coastal waters responds to ocean warming"

Esther Portela 
University of Tasmania, Australia
"Physical mechanisms driving oxygen uptake by the ocean interior"

You can watch the GO₂NE Webinar 21 June 2022 No 13 recording . 

Source: Springer Link 
Authors: Prince Prakash et al.
DOI: 10.1007/s10872-022-00644-7 

Abstract

"The Southern Ocean (SO) plays a critical role in global ocean productivity and carbon cycling. Bio-Argo floats deployed in the Indian sector of the Southern Ocean provides new insights into the biogeochemical processes. Here we report significantly higher dissolved oxygen (DO) (~鈥�310 渭mol/kg) in summer of 2014鈥�2015 for one float (F1) and winter of 2014 in other float (F2) at sub-surface layer in the subantarctic region of the SO. The summer DO peak in F1 was 10% higher than those during the summer of succeeding year, while the winter DO peak in F2 was 20% higher than those during the winter of succeeding year. [...]."

Source: Wiley Online Library
Authors: Jenna Pearson et al.
DOI: 10.1029/2021GB007192

Abstract

"Coastal hypoxia鈥攈armfully low levels of oxygen鈥攊s a mounting problem that jeopardizes coastal ecosystems and economies. The northern Indian Ocean is particularly susceptible due to human-induced impacts, vast naturally occurring oxygen minimum zones, and strong variability associated with the seasonal monsoons and interannual Indian Ocean Dipole (IOD). We assess how natural factors influence the risk of coastal hypoxia by combining a large set of oxygen measurements with satellite observations to examine how the IOD amplifies or suppresses seasonal hypoxia tied to the Asian Monsoon. We show that on both seasonal and interannual timescales hypoxia is controlled by wind- and coastal Kelvin wave-driven upwelling of oxygen-poor waters onto the continental shelf and reinforcing biological feedbacks (increased subsurface oxygen demand). [...]."

Source: Science Direct
Authors: Alberto S谩nchez et al. 
DOI: 10.1016/j.jmarsys.2022.103732

Abstract

"Deoxygenation of the water column in the oceans and in the oxygen minimum zone (OMZ) has become relevant due to its connection with global climate change. The variability of the OMZ has been inferred by in situ measurements for the last 70 years and qualitatively assessed through the monitoring of trace elements and the nitrogen stable isotope ratio (未15N) of organic matter on several time scales. The V, Ni, Mo and U concentrations in surface sediments and the dissolved oxygen concentration in the water column of La Paz Bay and the Mazatl谩n margin were used to propose an exponential regression model. This model will allow the inference of the dissolved oxygen concentration in the sedimentary records from the Alfonso Basin in La Paz Bay and in the Mazatl谩n margin over the last 250 years. [...]."

Source: Science Direct 
Authors: David J. Hughes et al.
DOI: 10.1016/j.marpolbul.2022.113722

Abstract

"Hypoxia (low oxygen stress) is increasingly reported on coral reefs, caused by ocean deoxygenation linked to coastal nutrient pollution and ocean warming. While the ability to regulate respiration is a key driver of hypoxia tolerance in many other aquatic taxa, corals' oxyregulatory capabilities remain virtually unexplored. Here, we examine O2-consumption patterns across 17 coral species under declining O2partial pressure (pO2). All corals showed ability to oxyregulate, but total positive regulation (Tpos) varied between species, ranging from 0.41 (Pocillopora damicornis) to 2.42 (P. acuta). [...]."

Source: PNAS 
Authors: Jitao Chen et al.
DOI: 10.1073/pnas.2115231119

Abstract

"Piecing together the history of carbon (C) perturbation events throughout Earth鈥檚 history has provided key insights into how the Earth system responds to abrupt warming. Previous studies, however, focused on short-term warming events that were superimposed on longer-term greenhouse climate states. Here, we present an integrated proxy (C and uranium [U] isotopes and paleo CO2) and multicomponent modeling approach to investigate an abrupt C perturbation and global warming event (鈭�304 Ma) that occurred during a paleo-glacial state. We report pronounced negative C and U isotopic excursions coincident with a doubling of atmospheric CO2 partial pressure and a biodiversity nadir. [...]."

Source: Springer Link
Authors: Pratima M. Kessarkar et al. 
DOI: 10.1007/s12040-022-01823-2 

Abstract

"The Arabian Sea encompasses oxygen minimum zone with denitrifying conditions. For the present study, sediments were collected across three transects off Goa transect (GT), Mangalore transect (MT) and Kochi transect (KT) in contact with water column dissolved oxygen (DO) range of 1.4鈥�118.0鈥吢礛. Sediments were investigated for texture, clay mineralogy, total organic carbon (Corg), total nitrogen, CaCO3, 未15N, 未13C, metal content to infer their distribution with changing DO and their use as possible palaeo-proxies. The Corg (0.9鈥�8.6%) is largely marine and 未15N from GT and MT preserves signatures of higher water column denitrification. [...]."

Source: Wiley Online Library
Authors: Herd铆s G. R. Steinsd贸ttir et al. 
DOI: 10.1111/1462-2920.16003

Abstract

"Coastal waters are a major source of marine methane to the atmosphere. Particularly high concentrations of this potent greenhouse gas are found in anoxic waters, but it remains unclear if and to what extent anaerobic methanotrophs mitigate the methane flux. Here we investigate the long-term dynamics in methanotrophic activity and the methanotroph community in the coastal oxygen minimum zone (OMZ) of Golfo Dulce, Costa Rica, combining biogeochemical analyses, experimental incubations and 16S rRNA gene sequencing over 3 consecutive years. [...]."

Source: Wiley Online Library
Authors: Taka Ito et al.
DOI: 10.1029/2021GB007151

Abstract

"Large-scale loss of oxygen under global warming is termed 鈥渙cean deoxygenation鈥� and is caused by the imbalance between physical supply and biological consumption of oxygen in the ocean interior. Significant progress has been made in the theoretical understanding of ocean deoxygenation; however, many questions remain unresolved. The oxygen change in the tropical thermocline is poorly understood, with diverging projections among different models. Physical oxygen supply is controlled by a suite of processes that transport oxygen-rich surface waters into the interior ocean, which is expected to weaken due to increasing stratification under global warming. [...]."

Source: Science Direct
Authors: Feifei Zhang et al.
DOI: 10.1016/j.epsl.2022.117421

Abstract

"The mid-Ludfordian Lau carbon isotope excursion (Lau CIE) represents the largest positive carbon isotope excursion in the Phanerozoic (~9鈥�), coincident with the biodiversity loss of many marine animal clades. Two main explanations for the Lau CIE are enhanced organic carbon burial via increased marine productivity and preservation-driven expansion of anoxia. While these two explanations are not mutually exclusive, the main driver of Lau CIE is yet to be constrained. Here, we resolve this longstanding debate using barium isotopes (未138 Ba) of marine carbonates deposited across the Lau CIE. [...]."

Source: Springer Link
Authors: Tayler M. Clarke et al. 
DOI: 10.1007/s10641-022-01256-2

Abstract

"The organisms that inhabit Oxygen Minimum Zones (OMZ) have specialized adaptations that allow them to survive within a very narrow range of environmental conditions. Consequently, even small environmental perturbations can result in local species distribution shifts that alter ecosystem trophodynamics. Here, we examined the effect of changing sea water temperatures and oxygen levels on the physiological performance and metabolic traits of the species forming marine demersal communities along the OMZ margins in the Costa Rican Pacific. The strong temperature and oxygen gradients along this OMZ margin provide a 鈥渘atural experiment鈥� to explore the effects of warming and hypoxia on marine demersal communities. [...]."

Source: Science Direct
Authors: Syed Azharuddin et al. 
DOI: 10.1016/j.jseaes.2022.105094

Abstract

"The Arabian Sea is characterized by a strong Oxygen Minimum Zone (OMZ) bearing sub-oxic conditions at the intermediate water depth. We analyzed a sediment core near the upper margin of OMZ (174 m water depth) from offshore Saurashtra, northeastern (NE) Arabian Sea to reconstruct multi-proxy biogeochemical response in the area during the Early-Middle Holocene (鈭�10鈥�4 ka before present). The results indicate lower foraminiferal productivity (both benthic and planktic) and weak sub-surface denitrification causing mild OMZ conditions at the study site during the early Holocene (鈭�10鈥�8 ka). Subsequently, an increased foraminiferal productivity and sub-surface (both the water column and sediment) denitrification in the area led to intensified OMZ conditions during the mid-Holocene (after 鈭�8 ka). [...]."

Source: Science Direct 
Authors: Feifei Zhang et al.
DOI: 10.1016/j.epsl.2022.117437

Abstract

"The Earth's redox evolution has been commonly assumed to have played a key role in shaping the evolutionary history of the biosphere. However, whether and how shifts in marine redox conditions are linked to key biotic events 鈥� foremost the rise of animals and the ecological expansion of eukaryotic algae in the late Proterozoic oceans 鈥� remains heavily debated. Our current picture of global marine redox evolution during this critical interval is incomplete. This is particularly the case for the Tonian Period (鈭�1.0 to 鈭�0.717 Ga), when animals may have diverged and when eukaryotic algae began their rise in ecological importance. Here, we present new uranium isotope (U) measurements from Tonian carbonates to fill this outstanding gap. [...]."

Source: Science Direct
Authors: Sharon Sharon & Christina L. Belanger
DOI: 10.1016/j.quascirev.2022.107412

Abstract

"Dysoxic events are well-studied in Pleistocene and Holocene marinesediment records from the North Pacific using faunal, sedimentological, and geochemical paleo-oxygenation proxies. However, differences in proxy sensitivity and local conditions make it difficult to quantify the relative severity of dysoxia across the North Pacific. Here, we use multivariate analyses of taxonomically standardized benthic foraminiferal assemblages to quantitatively compare the severity and duration of dysoxic events at four intermediate depth sites within oxygen minimum zones in the Gulf of Alaska (GoA), Santa Barbara Basin, and Baja California Sur. Unlike previous faunal dissolved oxygen indices, the metric developed here incorporates the total faunal assemblage and is better correlated with co-registered geochemical proxies. [...]."

Source: Wiley Online Library
Authors: Emily M. Donham et al. 
DOI: 10.1111/gcb.16125

Abstract

"Understanding species鈥� responses to upwelling may be especially important in light of ongoing environmental change. Upwelling frequency and intensity are expected to increase in the future, while ocean acidification and deoxygenation are expected to decrease the pH and dissolved oxygen (DO) of upwelled waters. However, the acute effects of a single upwelling event and the integrated effects of multiple upwelling events on marine organisms are poorly understood. Here, we use in situ measurements of pH, temperature, and DO to characterize the covariance of environmental conditions within upwelling-dominated kelp forest ecosystems. We then test the effects of acute (0鈥�3 days) and chronic (1鈥�3 months) upwelling on the performance of two species of kelp forest grazers, the echinoderm, Mesocentrotus franciscanus, and the gastropod, Promartynia pulligo. We exposed organisms to static conditions in a regression design to determine the shape of the relationship between upwelling and performance and provide insights into the potential effects in a variable environment. We found that respiration, grazing, growth, and net calcification decline linearly with increasing upwelling intensity for M. francicanus over both acute and chronic timescales. [...]."

Source: Science Direct
Authors: Tianchen He et al. 
DOI: 10.1016/j.gloplacha.2022.103771

Abstract

"Warming-induced marine anoxia has been hypothesized as an environmental stressor for the end-Triassic mass extinction (ETME), but links between the spread of marine anoxia and the two phases of extinction are poorly constrained. Here, we report iron speciation and trace metal data from the Bristol Channel Basin and Larne Basin of the NW European epicontinental sea (EES), spanning the Triassic鈥揓urassic (T鈥揓) transition (~ 202鈥�200 Ma). Results show frequent development of anoxic-ferruginous conditions, interspersed with ephemeral euxinic episodes in the Bristol Channel Basin during the latest Rhaetian, whereas the contemporaneous Larne Basin remained largely oxygenated, suggesting heterogeneous redox conditions between basins. Subsequently, more persistent euxinic conditions prevailed across the T鈥揓 boundary in both basins, coinciding precisely with the second phase of the ETME. [...]."

Source: Nature
Authors: Hironao Matsumoto et al.
DOI: 10.1038/s41467-021-27817-0

Abstract

"During the mid-Cretaceous, the Earth experienced several environmental perturbations, including an extremely warm climate and Oceanic Anoxic Events (OAEs). Submarine volcanic episodes associated with formation of large igneous provinces (LIPs) may have triggered these perturbations. The osmium isotopic ratio (187Os/188Os) is a suitable proxy for tracing hydrothermal activity associated with the LIPs formation, but 187Os/188Os data from the mid-Cretaceous are limited to short time intervals. Here we provide a continuous high-resolution marine 187Os/188Os record covering all mid-Cretaceous OAEs. Several OAEs (OAE1a, Wezel and Fallot events, and OAE2) correspond to unradiogenic 187Os/188Os shifts, suggesting that they were triggered by massive submarine volcanic episodes. However, minor OAEs (OAE1c and OAE1d), which do not show pronounced unradiogenic 187Os/188Os shifts, were likely caused by enhanced monsoonal activity. [...]."

Source: Science Direct
Authors: Dongtao Xu et al.
DOI: 10.1016/j.gca.2022.02.019

Abstract

"Pulses of the Ediacaran ocean oxygenation were inferred from strong enrichments of redox-sensitive elements (RSEs; particularly Mo, V, U, Re) and negative pyritesulfur isotopes (未34Spy) in black shales of the Doushantuo Formation in South China. These oceanic oxygenation events (OOEs) have been challenged by the lack of comparable RSE enrichments in correlative strata of northwestern Canada. Here we report four positive chromium isotope (未53Cr) excursions with peak values (+0.79 卤 0.03鈥� to +1.45 卤 0.06鈥�; 2SD) close to the average 未53Cr value of the modern ocean (+1.0 卤 0.3鈥�) at the intervals of OOEs, which are separated by low 未53Cr values close to that of the bulk silicate Earth (BSE, 鈭�0.124 卤 0.101鈥�). The positive 未53Cr excursions could be explained by episodic input of oxygenated water from the open ocean to the restricted Nanhua basin, or pulses of ocean oxygenation during the Ediacaran-early Cambrian. The two interpretations can explain the majority of the geochemical data available from the Wuhe section, but both have limitations. [...]."

Source: Science Direct
Authors: Alberto S谩nchez et al. 
DOI: 10.1016/j.csr.2022.104716

Abstract

"The Gulf of California is a highly biodiverse marine basin located in the northeast Mexican Pacific Ocean. In the past three decades, this basin has experienced increased hypoxia in shallow waters, which threatens its coastal ecosystems. The aim of this study is to analyze 未15N and 未13C isotopes of organic matter in coastal sediments to characterize sources of primary production and shifts in biogeochemical processes that reflect increasing oxygen deficiency in the shallow coast of the eastern Gulf of California. Surface sediments samples were collected from 8 to 47 m deep along the coastal margin of Sinaloa and Sonora. This region is characterized by the development of anthropogenic activities, which could be the main source of organic matter evidenced in the marine environment. [...]."

Source: Science Direct
Authors: Anju Mallissery et al.
DOI: 10.1016/j.jmarsys.2021.103680

Abstract

"The central and northeast Arabian Sea (AS) has an intense and thick oxygen minimum zone (OMZ) and denitrification zone. It is comparable with the strongest OMZ of the north-equatorial Pacific Ocean. Denitrification in the AS is revisited using a set of cruise observations collected during February鈥揗arch of 2009 by the Centre for MarineLivingResources, India. The region possesses one of the most robust N* depleted water reaching as low as -20 渭mol l鈭�1 at depths (~600 m). In AS, the oxygen depletion is mainly due to sluggish circulation, weak lateral and vertical ventilation. The biological respiration in oxygen deficit condition depletes nitrate and further modifies the Redfield ratio at intermediate depths (200-600 m) from 16N:1P to 8N:1P. [...]."

Source: Science Direct
Authors: Zhuo Chen et al.
DOI: 10.1016/j.scitotenv.2021.152862

Abstract

"Picoeukaryotic communities respond rapidly to global climate change and play an important role in marine biological food webs and ecosystems. The formation of oxygen minimum zones (OMZ) is facilitated by the stratification of seawater and higher primary production in the surface layer, and the marine picoeukaryotic community this low-oxygen environment is topic of interest. To better understand the picoeukaryotic community assembly mechanisms in an OMZ, we collected samples from the Bay of Bengal (BOB) in October and November 2020 and used 18S rDNA to study the picoeukaryotic communities and their community assembly mechanisms that they are controlled by in deep-sea and hypoxic zones. The results show that deterministic and stochastic processes combine to shape picoeukaryotic communities in the BOB. [...]."

Source: GeoScienceWorld
Authors: Zheng Tang et al. 
DOI: 10.2113/2022/1835176

Abstract

"We present new geochemical evidence of changes in oxygenation of the deep Antarctic Pacific over the last 770鈥塳yr. Our data are derived from redox-sensitive metals and export production proxies extracted from gravity core ANT34/A2-10 at 4217鈥塵 water depth. Our results show that oxygen levels in the deep Antarctic Zone (AZ) varied in line with the release of deeply sequestered remineralized carbon to the atmosphere during glacial鈥搃nterglacial (G鈥揑G) cycles, with lower oxygen concentrations and more carbon storage during glacial periods. Subsequent reductions in the amount of carbon stored at depth were closely associated with improved ventilation during glacial terminations. [...]."

Source: Geoscientific Model Development 
Authors: Kai Wang et al. 
DOI: 10.5194/gmd-15-1017-2022

Abstract

"The tropical Pacific Ocean holds the two largest oxygen minimum zones (OMZs) in the world's oceans, showing a prominent hemispheric asymmetry, with a much stronger and broader OMZ north of the Equator. However, many models have difficulties in reproducing the observed asymmetric OMZs in the tropical Pacific. Here, we apply a fully coupled basin-scale model to evaluate the impacts of stoichiometry and the intensity of vertical mixing on the dynamics of OMZs in the tropical Pacific. We first utilize observational data of dissolved oxygen (DO) to calibrate and validate the basin-scale model. Our model experiments demonstrate that enhanced vertical mixing combined with a reduced O:C utilization ratio can significantly improve our model capability of reproducing the asymmetric OMZs. Our study shows that DO concentration is more sensitive to biological processes over 200鈥�400鈥塵 but to physical processes below 400鈥塵. [...]." 

Source: Science Direct
Authors: Yang Yu et al.
DOI: 10.1016/j.precamres.2021.106527

Abstract

"Oxygen availability is crucial for the evolution of eukaryotes in geological history, yet detailed Mesoproterozoic oceanic-atmospheric redox conditions remain enigmatic. In contrast to the generally accepted hypothesis of an anoxic mid-Proterozoic ocean and atmosphere, several transient oxygenation events may occur at the Earth鈥檚 surface during the Mesoproterozoic, especially for the period around 1.4 Ga. The North China Platform develops one of the most complete and continuous Mesoproterozoic stratigraphic successions globally, preserving key information on the redox state of the surface ocean鈥揳tmosphere system during the mid-Proterozoic. [...]."

Source: Nature 
Authors: Matthias Kranner et al. 
DOI: 10.1038/s41598-022-05295-8

Abstract

"Marine oxygen minimum zones (OMZs) trap greenhouse gases, reduce livable habitats, a critical factor for these changes is the amount of dissolved oxygen (DO). The frequently used tool to reconstruct DO values, the Benthic Foraminifera Oxygen Index (BFOI), showed major shortcomings and lacks effectiveness. Therefore, we enhanced the BFOI and introduce enhanced BFOI (EBFOI) formulas by using all available data benthic foraminifers provide, calculating the whole livable habitat of benthic foraminifers, including bottom water oxygenation (BWO) and pore water oxygenation (PWO). Further, we introduce for the first time a transfer function to convert EBFOI vales directly into DO values, increasing efficiency by up to 38%. [...]."

Source: Science Direct
Authors: Maya Elrick et al.
DOI: 10.1016/j.epsl.2022.117410

Abstract

"The middle Paleozoic (鈭�420-350 Myr) records a major increase in ocean-atmosphere oxygen levels; however, the timing and pattern of oxygenation are poorly constrained. Two well-dated North American locations in Nevada and Illinois were used to generate a high-resolution U-isotopic profile (U) spanning 鈭�70 Myr of the middle Paleozoic. Stratigraphic and geochemical data support the interpretation that the Nevada profile represents a near-primary record of global-ocean redox variations. First-order U trends indicate strongly reducing oceans during the late Silurian and Early Devonian, terminated by a major oxygenation event near the Emsian-Eifelian boundary (鈭�395 Ma). More oxic seawater conditions persisted for the next 30+ Myr, but were punctuated by multiple Myr-scale anoxic events during the Middle-Late Devonian and Early Mississippian that correlate with known global biotic crises, positive C excursions, and widespread organic-rich facies deposition. [...]."

Source: Biogeosciences
Authors: Jannes Koelling et al. 
DOI: 10.5194/bg-19-437-2022

Abstract

"The Labrador Sea in the North Atlantic Ocean is one of the few regions globally where oxygen from the atmosphere can reach the deep ocean directly. This is the result of wintertime deep convection, which homogenizes the water column to a depth of up to 2000鈥塵 and brings deep water undersaturated in oxygen into contact with the atmosphere. In this study, we analyze how the intense oxygen uptake during Labrador Sea Water (LSW) formation affects the properties of the outflowing deep western boundary current, which ultimately feeds the upper part of the North Atlantic Deep Water layer in much of the Atlantic Ocean. [...]."

Source: Nature 
Authors: Katsuro Katsumata et al.
DOI: 10.1038/s41597-022-01212-w

Abstract

"Despite technological advances over the last several decades, ship-based hydrography remains the only method for obtaining high-quality, high spatial and vertical resolution measurements of physical, chemical, and biological parameters over the full water column essential for physical, chemical, and biological oceanography and climate science. The Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) coordinates a network of globally sustained hydrographic sections. These data provide a unique data set that spans four decades, comprised of more than 40 cross-ocean transects. The section data are, however, difficult to use owing to inhomogeneous format. The purpose of this new temperature, salinity, and dissolved oxygen data product is to combine, reformat and grid these data measured by Conductivity-Temperature-Depth-Oxygen (CTDO) profilers in order to facilitate their use by a wider audience. [...]."

Source: Wiley Online Library 
Authors: Yuntao Zhou et al.
DOI: 10.1029/2022GL097724

Abstract

"Due to climate change, global oceanic dissolved oxygen (DO) has been decreasing, and oxygen minimum zones (OMZs) have been expanding. Here, we estimate the annual global and regional OMZ areas using geostatistical regression combined with Monte Carlo. From 1960 to 2019, annual global OMZ20 (DO < 20 渭mol/kg) and OMZ60 (DO < 60 渭mol/kg) areas cover 5%鈥�14% and 15%鈥�32% of the global ocean, respectively. The global and most regional OMZ areas after the late 2000s were all significantly larger than those in previous years. [...]."

"The Open Science Conference on Eastern Boundary Upwelling Systems (EBUS): Past, Present and Future and the Second International Conference on the Humboldt Current System are planned for September 19 - 23 in Lima, Peru. Although the conference aims to be in-person, options for virtual participation will be provided.

The meeting will bring together PhD students, early career scientists and world experts to understand, review, and synthesize what is known about dynamics, sensitivity, vulnerability and resilience of Eastern Boundary Upwelling Systems and their living resources to climate variability, change and extreme events."

For further information, please visit the .

Source: Science Direct
Authors: Tianchen He et al.
DOI: 10.1016/j.gloplacha.2022.103770

Abstract

"The end-Triassic mass extinction (ETME) was associated with intensified deep-water anoxia in epicontinental seas and mid-depth waters, yet the absolute oxygenation state in the shallow ocean is uncharacterized. Here we report carbonate-associated iodine data from the peritidal Mount Sparagio section (Southern Italy) that documents the ETME (~ 200 Ma) in the western Tethys. We find a sharp drop in carbonate I/(Ca + Mg) ratios across the extinction horizon and persisting into the Early Jurassic. [...]."

"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 30 March 2022 No 12

Moderator:
Boris Dewitte
CEAZA, Chile

Speakers:
Alexandra Parouffe
LEGOS, France
"Future habitability of the South East Pacific in a changing environment"

Andrew Babbin
Massachusetts Institute of Technology, USA
"A High-Resolution Atlas of the Eastern Tropical Pacific Oxygen Deficient Zones"

You can watch the GO₂NE Webinar 30 March 2022 No 12 recording . 

Source: Science Direct
Authors: Florian L眉skow et al. 
DOI: 10.1016/j.marenvres.2022.105566

Abstract

"Physical and topographic characteristics can structure pelagic habitats and affect the plankton community composition. For example, oxygen minimum zones (OMZs) are expected to lead to a habitat compression for species with a high oxygen demand, while upwelling of nutrient-rich deep water at seamounts can locally increase productivity, especially in oligotrophic oceanic waters. Here we investigate the response of the gelatinouszooplankton (GZ) assemblage and biomass to differing oxygen conditions and to a seamount in the Eastern Tropical North Atlantic (ETNA) around the Cape Verde archipelago. [...]."

"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 March 2022 No 11

Moderator:
Kirsten Isensee
IOC-UNESCO

Speakers:
Andreas Oschlies
黑料视频 Helmholtz Centre for Ocean Research Kiel, Germany
Marilaure Gr茅goire
University of Li猫ge, Belgium
"Introduction and overview on GOOD by co-chairs GO2NE"

Marilaure Gr茅goire
University of Li猫ge, Belgium
V茅ronique Gar莽on
Legos, France
"Assessing and predicting deoxygenation and ocean health in the open and coastal ocean"

Minhan Dai
Xiamen University, China
"Coastal hypoxia, COASTAL -SOS"

Karin Limburg
State University of New York College of Environmental Science & Forestry, USA and Department of Aquatic Resources, Swedish Agricultural University
"Project Breathless"

You can watch the GO₂NE Webinar 11 March 2022 No 11 recording .

Source: Springer Link
Authors: Klaus Wallmann et al.
DOI: 10.1007/s10533-022-00908-w 

Abstract

"A new box model is employed to simulate the oxygen-dependent cycling of nutrients in the Peruvian oxygen minimum zone (OMZ). Model results and data for the present state of the OMZ indicate that dissolved iron is the limiting nutrient for primary production and is provided by the release of dissolved ferrous iron from shelf and slope sediments. Most of the removal of reactive nitrogen occurs by anaerobic oxidation of ammonium where ammonium is delivered by aerobic organic nitrogen degradation. Model experiments simulating the effects of ocean deoxygenation and warming show that the productivity of the Peruvian OMZ will increase due to the enhanced release of dissolved iron from shelf and slope sediments. A positive feedback loop rooted in the oxygen-dependent benthic iron release amplifies, both, the productivity rise and oxygen decline in ambient bottom waters. [...]."

Source: Science Direct
Authors: Sudheesh Valliyodan et al.
DOI: 10.1016/j.pocean.2022.102742

Abstract

"The oxygen minimum zone (OMZ) in the eastern Arabian Sea (EAS, 鈭�6掳 to 21掳N), within Indian Exclusive Economic Zone (EEZ), is mapped, for the first time, for one year through ten repeated ship-based observations between December 2017 and January 2019 at seven to ten stations along the 2000 m depth contour. On an annual basis, the OMZ (<20 碌M oxygen) in the EAS varied between 60 and 1350 m; its thickness decreased from north to south. During the winter monsoon, the upper boundary of the OMZ in the north and south was deeper (150鈥�160 m) than the central EAS (鈭�110 m). [...]."

Source: Science Direct
Authors: Marina L茅vy et al.
DOI: 10.1016/B978-0-12-821512-8.00020-7

Abstract

"The oxygen content of the ocean interior largely results from a balance between respiration and advective ventilation, with only a small contribution from mixing processes. However, two important characteristics, which are key to future oxygen distribution in the ocean, primarily depend on the strength of ocean mixing. The first relates to the oxygen minimum zones (OMZ), which are wide O2-deficient mesopelagic layers inhospitable to most marine macro-fauna. We illustrate how mixing intensity controls the volume of all major OMZs. [...]."

"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 January 2022 No 10

Moderator:
Caroline Slomp
Utrecht University, The Netherlands

Speakers:
Niels van Helmond
Utrecht University, The Netherlands
"Sedimentary trace metals: a powerful indicator for bottom water redox conditions"

Laura Bristow
University of Southern Denmark
"Nitrogen cycling in anoxic waters: oxygen contamination and the need for in situ measurement"

You can watch the GO₂NE Webinar 26 January 2022 No 10 recording .

Source: Wiley Online Library
Authors: Rebecca J. Duncan et al.
DOI: 10.1111/nph.17868

Abstract

"Primary production in the Southern Ocean is dominated by diatom-rich phytoplankton assemblages, whose individual physiological characteristics and community composition are strongly shaped by the environment, yet knowledge on how diatoms allocate cellular energy in response to ocean acidification (OA) is limited. Understanding such changes in allocation is integral to determining the nutritional quality of diatoms and the subsequent impacts on the trophic transfer of energy and nutrients. [...]."