News

Cold-Water Coral Reefs in the Oxygen Minimum Zones Off West Africa

Abstract.

"The discoveries of large reefs within cold-water coral mound provinces revealed that the West African margin is a coral hotspot area in the Atlantic Ocean. The most striking observation is that cold-water corals thrive in extensive oxygen minimum zones under extreme conditions. This points to a wide tolerance of cold-water corals in these regions to low oxygen concentrations. The coral mound provinces off Mauritania, Angola, and Namibia, which are located in the centre of the local oxygen minimum zones, were selected as key study areas, and their regional oceanographic, bio-ecological, and geo-morphological settings are described in detail. [...]".

 

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

Read the full article here.


Can green hydrogen production be used to mitigate ocean deoxygenation? A scenario from the Gulf of St. Lawrence

Abstract.

"Ocean deoxygenation and expansion and intensification of hypoxia in the ocean are a major, growing threat to marine ecosystems. Measures currently used to protect marine biodiversity (e.g., marine protected areas) are ineffective in countering this threat. Here, we highlight the example of the Gulf of St. Lawrence in eastern Canada, where oxygen loss is not only due to eutrophication (which can be mitigated by nutrient controls) but also is a consequence of ocean circulation change and warming. Climate-related loss of oxygen will be an increasingly widespread source of risk to marine biodiversity over this century. [...]".

 

Source: Springer Nature
Authors: Douglas W. R. Wallace et al.
DOI: https://doi.org/10.1007/s11027-023-10094-1

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Climatic Changes in North Atlantic O2 Amplified by Temperature Sensitivity of Phytoplankton Growth

Abstract.

"Ocean warming is associated with a decline in the global oxygen (O2) inventory, but the ratio of O2 loss to heat gain is poorly understood. We analyzed historical variability in temperature (T), O2, and nitrate (N⁢O3−) in hydrographic observations and model simulations of the North Atlantic, a relatively well-sampled region that is important for deep ocean ventilation. Multidecadal fluctuations of O2 concentrations in subpolar thermocline waters (100–700 m) are correlated with changes in their heat content, with a slope 35% steeper than that expected from thermal solubility. [...]".

 

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

Read the full article here.


Sedimentary environment and benthic oxygenation history of the Upper Cretaceous Austin Chalk Group, south Texas...

Full title: "Sedimentary environment and benthic oxygenation history of the Upper Cretaceous Austin Chalk Group, south Texas: An integrated ichnological, sedimentological and geochemical approach"

Abstract.

"Oxygen concentration in the ocean is vital for sustaining marine ecosystems. While the potential impacts of deoxygenation on modern oceans are hard to predict, lessons can be learned from better characterizing past geological intervals formed under a greenhouse climate. The greenhouse Cretaceous containing several oceanic anoxic events [...]".

 

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

Read the full article here.


Hypoxia-tolerant zooplankton may reduce biological carbon pump efficiency in the Humboldt current system off Peru

Abstract.

"In the ocean, downward flux of particles produced in sunlit surface waters is the major component of the biological carbon pump, which sequesters atmospheric carbon dioxide and fuels deep-sea ecosystems. The efficiency of downward carbon transfer is expected to be particularly high in tropical upwelling systems where hypoxia occurring beneath the productive surface waters is thought to hamper particle consumption. However, observations of both particle feeders and carbon export in low-oxygen waters are scarce. Here, we provide evidence that hypoxia-tolerant zooplankton feed on sinking particles in the extensive Oxygen Minimum Zone (OMZ) off Peru. [...]".

 

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

Read the full article here.


Evolution and dynamics of the Arabian Sea oxygen minimum zone: Understanding the paradoxes

Abstract.

"The Arabian Sea hosts a perennial and intense oxygen minimum zone (OMZ) at 150–1200 m depths with O2 concentrations <0.5 ml/l. It is generally believed that the oxygen-depleted conditions at mid-water depths result from high rate of O2 consumption due to monsoon-driven productivity generating a high organic matter flux, combined with slow renewal of thermocline waters in the region. With global warming and increasing hypoxia, there is growing interest to better understand the various factors controlling oxygen conditions in the thermocline waters and the impact on the nutrient cycling and climate. [...]".

 

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

Read the full article here.


Reconstruction of dissolved oxygen in the Indian Ocean from 1980 to 2019 based on machine learning techniques

Abstract.

"Oceanic dissolved oxygen (DO) decline in the Indian Ocean has profound implications for Earth’s climate and human habitation in Eurasia and Africa. Owing to sparse observations, there is little research on DO variations, regional comparisons, and its relationship with marine environmental changes in the entire Indian Ocean. In this study, we applied different machine learning algorithms to fit regression models between measured DO, ocean reanalysis physical variables, and spatiotemporal variables. [...]".

 

Source: Frontiers in Marine Science
Authors: Sheng Huang et al.
DOI: https://doi.org/10.3389/fmars.2023.1291232

Read the full article here.


Editorial: Recent developments in oxygen minimum zones biogeochemistry

Abstract.

"Marine Oxygen Minimum Zones (OMZs) modulate biogeochemical cycles, and directly impact climate dynamics by influencing air-sea fluxes of the potent greenhouse gases methane and nitrous oxide (Levin, 2018). OMZs are formed in regions of weak oxygen (O2) supply from physical ventilation and high integrated microbial O2 demand fueled by downward organic flux from overlying surface waters. The ocean’s major OMZs are found in the Eastern Tropical South and North Pacific Ocean and the Arabian Sea and Bay of Bengal in the Indian Ocean (Karstensen et al., 2008; Stramma et al., 2008). [...]".

 

Source: Frontiers in Marine Science
Authors: Annie Bourbonnais et al.
DOI: https://doi.org/10.3389/fmars.2023.1333731

Read the full article here.


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