Ocean Oxygen: the role of the Ocean in the oxygen we breathe and the threat of deoxygenation
"EMB Future Science Brief No. 10 highlights the most recent science on Ocean oxygen, including causes, impacts and mitigation strategies of Ocean oxygen loss, and discusses whether “every second breath we take comes from the Ocean”. It closes with key policy, management and research recommendations to address Ocean deoxygenation and communicate more accurately about the role of the Ocean in Earth’s oxygen.
The sentence “every second breath you take comes from the Ocean” is commonly used in Ocean Literacy and science communication to highlight the importance of Ocean oxygen. [...]".
Source: European Marine Board
Authors: Marilaure Grégoire et al.
Decreasing O2 availability reduces cellular protein contents in a marine diatom
"Anthropogenic activities and climate change are exacerbating marine deoxygenation. Apart from aerobic organisms, reduced O2 also affects photoautotrophic organisms in the ocean. This is because without available O2, these O2 producers cannot maintain their mitochondrial respiration, especially under dim-light or dark conditions, which may disrupt the metabolism of macromolecules including proteins. We used growth rate, particle organic nitrogen and protein analyses, proteomics, and transcriptomics to determine cellular nitrogen metabolism of the diatom Thalassiosira pseudonana grown under three O2 levels in a range of light intensities [...]".
Source: Science Direct
Authors: Bokun Chen et al.
The response of nitrogen and sulfur cycles to ocean deoxygenation across the Cenomanian-Turonian boundary
"The Cretaceous Oceanic Anoxic Event 2 (OAE2) is a greenhouse episode of severe marine anoxia at the Cenomanian-Turonian boundary. This time interval is characterized by rising sea surface temperature, enhanced marine biological productivity, and widespread occurrence of organic-rich black shales. With an export of biological production to the deep ocean, organisms consume vast amounts of oxygen and subsequently utilize nitrate and sulfate as electron acceptors in organic matter degradation, thereby affecting biogeochemical cycles of nitrogen and sulfur. [...]".
Source: Science Direct
Authors: Ruixiang Zhai et al.
Indian Ocean glacial deoxygenation and respired carbon accumulation during mid-late Quaternary ice ages
"Reconstructions of ocean oxygenation are critical for understanding the role of respired carbon storage in regulating atmospheric CO2. Independent sediment redox proxies are essential to assess such reconstructions. Here, we present a long magnetofossil record from the eastern Indian Ocean in which we observe coeval magnetic hardening and enrichment of larger, more elongated, and less oxidized magnetofossils during glacials compared to interglacials over the last ~900 ka. Our multi-proxy records of redox-sensitive magnetofossils, trace element concentrations, and benthic foraminiferal Δδ13C consistently suggest a recurrence of lower O2 [...]".
Authors: Liao Chang et al.
Deoxygenation of the Baltic Sea during the last millennium
"Over the last 1,000 years, changing climate strongly influenced the ecosystem of coastal oceans such as the Baltic Sea. Sedimentary records revealed that changing temperatures could be linked to changing oxygen levels, spreading anoxic, oxygen-free areas in the Baltic Sea. However, the attribution of changing oxygen levels remains to be challenging. This work simulates a preindustrial period of 850 years, covering the Medieval Climate Anomaly (MCA) and the Little Ice Age using a coupled physical-biogeochemical model. [...]".
Source: Frontiers in Marine Science
Authors: Florian Börgel et al.
Role of climate variability on deep-water dynamics and deoxygenation during sapropel deposition ...
Full title: "Role of climate variability on deep-water dynamics and deoxygenation during sapropel deposition: New insights from a palaeoceanographic empirical approach"
"Modern marine settings are experiencing rapid deoxygenation mainly forced by global warming and anthropogenic eutrophication. Therefore, studies that assess the role of climate variability in large spatiotemporal deoxygenations during past climate changes are needed to better comprehend the consequences of the current global warming and ocean deoxygenation. [...]".
Source: Science Direct
Authors: Ricardo D. Monedero-Contreras et al.
A Selected Review of Impacts of Ocean Deoxygenation on Fish and Fisheries
"Oxygen is crucial for the survival of marine species. Yet, the ocean has experienced a loss of approximately 2% of its oxygen inventory since the last century, resulting in adverse impacts on marine life and ecosystems. In particular, changes in the gap between the supply and demand for dissolved oxygen lead to physiological and ecological variations, which cause alterations in habitats and food webs for fish and ecosystem services. These changes vary over time and by region, and the heterogeneous characteristics of marine species bring about non-linear consequences to human society. [...]".
Authors: Hongsik Kim et al.
Impact of deoxygenation and warming on global marine species in the 21st century
"Ocean temperature and dissolved oxygen shape marine habitats in an interplay with species' physiological characteristics. Therefore, the observed and projected warming and deoxygenation of the world's oceans in the 21st century may strongly affect species' habitats. Here, we implement an extended version of the Aerobic Growth Index (AGI), which quantifies whether a viable population of a species can be sustained in a particular location. We assess the impact of projected deoxygenation and warming on the contemporary habitat of 47 representative marine species covering the epipelagic, mesopelagic, and demersal realms. [...]".
Authors: Anne L. Morée et al.
Recent Deoxygenation of Patagonian Fjord Subsurface Waters Connected to the Peru–Chile Undercurrent and Equatorial Subsurface Water Variability
"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.
Acute hypoxia induces reduction of algal symbiont density and suppression of energy metabolism in the scleractinian coral Pocillopora damicornis
"Loss of oxygen in the ocean is accelerating and threatening the coral reef ecosystem. In this study, the impacts of hypoxia on the scleractinian coral Pocillopora damicornis were explored. The algal symbiont density, chlorophyll a + c2 content, energy consumption of corals, as well as energy available and consumption of their symbionts, decreased significantly post hypoxia stress. Meanwhile, the malondialdehyde contents in corals and symbionts, together with the caspase-3 activation level in corals, increased significantly in response to hypoxia stress. [...]".
Source: Science Direct
Authors: Kaidian Zhang et al.
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