News

Fossil-Bearing Concretions of the Araripe Basin Accumulated During Oceanic Anoxic Event 1b

Abstract.

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

 

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

Read the full article here.


Depth Variance of Organic Matter Respiration Stoichiometry in the Subtropical North Atlantic and the Implications for the Global Oxygen Cycle

Abstract.

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

 

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

Read the full article here.


Butterfly effect of shallow-ocean deoxygenation on past marine biodiversity

Abstract.

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

 

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

Read the full article here.


Vertical variation of bacterial production and potential role in oxygen loss in the southern Bay of Bengal

Abstract.

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

 

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

Read the full article here.


Widespread marine euxinia along the western Yangtze Platform caused by oxygen minimum zone expansion during the Capitanian mass extinction

Abstract.

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

 

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

Read the full article here.


Carbonate-hosted manganese deposits and ocean anoxia

Abstract.

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

 

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

Read the full article here.


Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming ...

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

Abstract.

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

 

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

Read the full article here.


Spatially heterogenous seawater δ34S and global cessation of Ca-sulfate burial during the Toarcian oceanic anoxic event

Abstract.

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

 

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

Read the full article here.


“Hypoxic” Silurian oceans suggest early animals thrived in a low-O2 world

Abstract.

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

 

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

Read the full article here.


Mentoring the next generation of ocean deoxygenation and acidification scientists

Intro.

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

Source: IOC-UNESCO

For further information, please read here


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

Abstract.

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

 

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

Read the full article here.


Stratigraphic architecture of the Tethyan Cenomanian-Turonian succession and OAE2 in the Dokan Area, Kurdistan Region, northeast Iraq

Abstract.

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

 

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

Read the full article here.


Job Offer in a project on understanding the consequences of marine heatwaves for terrestrial and marine systems in Northwestern Europe

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

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

You can find more details here.


Job Offer in paleoclimate modelling: sea-ice and past ocean oxygenation

PhD position at the School of Energy, Geoscience, Infrastructure and Society at the Heriot-Watt University  

"Are you interested in using climate models to help us understand the future? Consider applying for this PhD and join the Past Climate Change team at the Lyell Centre (Heriot-Watt University).

We are looking for an enthusiastic PhD candidate who will analyse the impact of different past (warm) climate states on sea-ice and effects on seawater oxygenation through model simulations."

You can find more details here


Job Offer in paleoceanographic proxies and past climate change: Past ocean oxygenation

PhD position at the School of Energy, Geoscience, Infrastructure and Society at the Heriot-Watt University  

"Are you interested in using past paleoceanographic reconstructions to help us understand our future planet? We are looking for an enthusiastic team-member to join the Past Climate Change Group https://pastclimates.site.hw.ac.uk/ at the Lyell Centre (Heriot-Watt, Edinburgh UK) as a PhD researcher. The project offers opportunities to work on data synthesis, proxy development and application."

You can find more details here


Job Offer in ocean biogeochemical dynamics

Postdoctoral researcher position at the School of Earth and Environmental Sciences at the University of St Andrews

"We are seeking a talented and creative postdoctoral researcher to work on ocean biogeochemical dynamics using observations, numerical models, and theory. Candidates should have a high level of technical skill in data analysis, and a strong grasp of ocean circulation and biogeochemistry. The position is initially available for two years, with the possibility of extension.  

The ocean plays a fundamental role in global biogeochemical cycling, with impacts on climate, planetary habitability, and ecosystem dynamics. Large-scale changes in these cycles – such as that of carbon and oxygen – are being observed or are predicted in the coming decades and centuries. For example, widespread deoxygenation and acidification are expected by the end of the 21st century, with potentially severe ramifications for both marine life and climate feedbacks. Understanding the mechanisms behind these changes is inhibited by a chronic sparsity of observations. Novel theoretical and analytical approaches are required to deepen our understanding of oceanic biogeochemical cycles and their observed changes, and to predict their future evolution and the consequences therein."

You can find more details here


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

Abstract.

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

 

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

Read the full article here.


Widespread marine euxinia along the western Yangtze Platform caused by oxygen minimum zone expansion during the Capitanian mass extinction

Abstract.

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

 

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

Read the full article here.


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