News

Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia

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

Read the full article here.


Spatial and Temporal Redox Heterogeneity Controlled by a Fe(II), Anoxic Upwelling System in the Early Mesoproterozoic Ocean

Abstract. 

"The availability of oxygen and nutrients during the Mesoproterozoic (1.6–1.0 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. [...]".

 

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

Read the full article here.


Recent Deoxygenation of Patagonian Fjord Subsurface Waters Connected to the Peru–Chile Undercurrent and Equatorial Subsurface Water Variability

Abstract.

"In recent decades, global dissolved oxygen (DO) measurements have registered a decrease of ∼1%–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: Wiley Online Library
Authors: Pamela Linford et al.
DOI: https://doi.org/10.1029/2022GB007688

Read the full article here.


A compendium of bacterial and archaeal single-cell amplified genomes from oxygen deficient marine waters

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

Read the full article here.


Do phytoplankton require oxygen to survive? A hypothesis and model synthesis from oxygen minimum zones

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) [...]". 

 

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

Read the full article here.


Redox conditions and ecological resilience during Oceanic Anoxic Event 2 in the Western Interior Seaway

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–Turonian OAE (OAE2; ∼94 Ma), whereas the Western Interior Seaway (WIS) experienced oxygenation at this time. Here, organic geochemical and palynological data generated from Cenomanian–Turonian 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: Libby J. Robinson et al.
DOI: https://doi.org/10.1016/j.palaeo.2023.111496

Read the full article here.


Global oceanic anoxia linked with the Capitanian (Middle Permian) marine mass extinction

Abstract. 

"The timing and causation of the Capitanian (late Middle Permian) biocrisis remain controversial. Here, a detailed uranium-isotopic (δ238U) 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 δ238U excursions indicate two distinct OAEs, a mid-Capitanian (OAE-C1) and an end-Capitanian (OAE-C2) event. [...]".

 

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

Read the full article here.


Mesozoic Oceanic Anoxic Events and the Associated Black Shale Deposits as a Potential Source of Energy

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–Turonian. 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: Springer Nature
Authors: Tarek Anan & Adam El-Shahat 
DOI: https://doi.org/10.1007/978-3-030-95637-0_7

Read the full article here.


Phytoplankton dynamics and nitrogen cycling during Oceanic Anoxic Event 2 (Cenomanian/Turonian) in the upwelling zone of the NE proto-North Atlantic

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 [...]". 

 

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

Read the full article here.


Mitigation of oxygen decline in fjords by freshwater injection

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: Dag L. Aksnes et al.
DOI: https://doi.org/10.1016/j.ecss.2023.108286 

Read the full article here.


Hypoxia stress induces hepatic antioxidant activity and apoptosis, but stimulates immune response and immune-related gene expression in black rockfish

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 [...]".

 

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

Read the full article here.


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