"The oceans are losing oxygen. Numerous studies based on direct measurements in recent years have shown this. Since water can dissolve less gas as temperatures rise, these results were not surprising. In addition to global warming, factors such as eutrophication of the coastal seas also contribute to the ongoing deoxygenation. [...]"

Source: Phys.org

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Abstract.

"Oceanic anoxic events have been associated with warm climates in Earth history, and there are concerns that current ocean deoxygenation may eventually lead to anoxia. Here we show results of a multi-millennial global-warming simulation that reveal, after a transitory deoxygenation, a marine oxygen inventory 6% higher than preindustrial despite an average 3 °C ocean warming. [...]"

Source: Nature Communications
Authors: Andreas Oschlies et al.
DOI: 10.1038/s41467-019-10813-w

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Abstract.

"Dissolved organic matter (DOM) is a critical component in aquatic ecosystems, yet its seasonal variability and reactivity remain not well constrained. These were investigated at the land-ocean interface of a subtropical river (Minjiang River, SE China), using absorption and fluorescence spectroscopy. [...]"

Source: Environmental Science and Pollution Research
Authors: Liyang Yang et al.
DOI: 10.1007/s11356-019-05700-2

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Abstract.

"Globally, there has been a decrease in dissolved oxygen in the oceans, that is more pronounced in coastal waters, resulting in more frequent hypoxia exposure for many marine animals. Managing hypoxia requires an understanding of the dynamics of dissolved oxygen (DO) where it occurs. The French coast facing the Bay of Biscay (N-E Atlantic Ocean) hosts at least a dozen tidal and turbid estuaries, but only the large estuaries of the Gironde and the Loire, are subject to a continuous monitoring. [...]"

Source: Frontiers in Marine Science 
Authors: Sabine Schmidt et al.
DOI: 10.3389/fmars.2019.00352

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Abstract.

"It has been suggested that giant Antarctic marine invertebrates will be particularly vulnerable to declining O2 levels as our ocean warms in line with current climate change predictions. Our study provides some support for this oxygen limitation hypothesis, with larger body sizes being generally more sensitive to O2 reductions than smaller body sizes. [...]"

Source: Philosophical Transactions of the Royal Society B
Authors: John I. Spicer  and Simon A. Morley
DOI: 10.1098/rstb.2019.0034

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"Researchers have presented support for the theory that marine invertebrates with larger body size are generally more sensitive to reductions in oxygen than smaller animals, and so will be more sensitive to future global climate change. However, evolutionary innovation can to some extent offset any respiratory disadvantages of large body size. [...]"

Source: Science Daily / University of Plymouth

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Abstract.

"More than half of the global ocean floor is draped by nutrient-starved sediments characterized by deep oxygen penetration and a prevalence of oxidized nitrogen. Despite low energy availability, this habitat hosts a vast microbial population, and geochemical characteristics suggest that nitrogen compounds are an energy source critical to sustaining this biomass. [...]"

Source: Scientific Reports
Authors: Rui Zhao et al.
DOI: 10.1038/s41598-019-44585-6

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Abstract.

"Upwelling of cold, nutrient-rich water from the oxygen minimum zone (OMZ) off Peru sustains the world’s highest production of forage fish, mostly composed of anchovy (Engraulis ringens). However, the potential impacts of climate change on upwelling dynamics and thus fish productivity in the near future are uncertain. Here, we reconstruct past changes in fish populations during the last 25,000 years to unravel their response to changes in OMZ intensity and productivity. [...]"

Source: Progress in Oceanography
Authors: RenatoSalvatteci et al.
DOI: 10.1016/j.pocean.2019.05.006

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Abstract.

"Offshore Antarctic polynyas—large openings in the winter sea ice cover—are thought to be maintained by a rapid ventilation of deep-ocean heat through convective mixing. These rare phenomena may alter abyssal properties and circulation, yet their formation mechanisms are not well understood. Here we demonstrate that concurrent upper-ocean preconditioning and meteorological perturbations are responsible for the appearance of polynyas in the Weddell Sea region of the Southern Ocean. [...]"

Source: Nature
Authors: Ethan C. Campbell et al.
DOI: 10.1038/s41586-019-1294-0

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"JUST OFF THE coast of Louisiana and Texas where the Mississippi River empties, the ocean is dying. The cyclical event known as the dead zone occurs every year, but scientists predict that this year's could be one of the largest in recorded history. Annual spring rains wash the nutrients used in fertilizers and sewage into the Mississippi. That fresh water, less dense than ocean water, sits on top of the ocean, preventing oxygen from mixing through the water column. Eventually those freshwater nutrients can spur a burst of algal growth, which consumes oxygen as the plants decompose. [...]"

Source: National Geographic

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