Abstract. 

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

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

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Abstract. 

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

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

Read the full article here.

Opening of one position for a 4-year Ph.D. or 3-year mobility postdoc for working on Fish Modelling in the Black Sea

"This position is offered in the frame of the recently funded 4-year Horizon-Europe project NECCTON  (New Copernicus Capability for Trophic Ocean Networks) and is available under a joint supervision at the Liège University (MAST-FOCUS group, Department of Astrophysics, Geophysics and Oceanography), the Royal Netherlands Institute for Sea Research (NIOZ) in the Nederland and the University of Maryland Center for Environmental Science (US). The research project aims at modelling the dynamics of selected fish species (e.g. anchovies, horse mackerel, sprat) in the Black Sea to assess the impact of past and projected environmental changes (e.g. deoxygenation, warming, fishing) on fish distribution and stocks." 

You can find more details in this document. 

Abstract. 

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

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

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Abstract. 

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

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

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Abstract. 

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

Source: Science Direct
Authors: Johann Müller et al.
DOI: https://doi.org/10.1016/j.gloplacha.2023.104067 

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Abstract. 

"Ocean deoxygenation is predicted to threaten marine ecosystems globally. However, current and future oxygen concentrations and the occurrence of hypoxic events on coral reefs remain underexplored. Here, using autonomous sensor data to explore oxygen variability and hypoxia exposure at 32 representative reef sites, we reveal that hypoxia is already pervasive on many reefs. Eighty-four percent of reefs experienced weak to moderate (≤153 µmol O2 kg−1to ≤92 µmol O2 kg−1) hypoxia and 13% experienced severe (≤61 µmol O2 kg−1) hypoxia. Under different climate change scenarios based on four Shared Socioeconomic Pathways (SSPs) [...]".

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

Read the full article here.

Abstract. 

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

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

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Abstract. 

"Photosynthesis produces molecular oxygen, but it is the burial of organic carbon in sediments that has allowed this O2 to accumulate in Earth’s atmosphere. Yet many direct controls on the preservation and burial of organic carbon have not been explored in detail. For modern Earth, it is known that reactive iron phases are important for organic carbon preservation, suggesting that the availability of particulate iron could be an important factor for the oxygenation of the oceans and atmosphere over Earth history. Here we develop a theoretical model to investigate the effect of mineral–organic preservation on the oxygenation of the Earth, supported by a proxy [...]".

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

Read the full article here.

Call for paper manuscripts closing tomorrow

This is a quick reminder that the call for paper manuscripts for a special issue on "Constraining Uncertainties in Hindcasts and Future Projections of Marine Deoxygenation" in Frontiers in Marine Science ends tomorrow, 7 April 2023. 

Further information: https://www.frontiersin.org/research-topics/24190/constraining-uncertainties-in-hindcasts-and-future-projections-of-marine-deoxygenation.