Our Vanishing World: Oceans

"As the human onslaught against life on Earth accelerates, no part of the biosphere is left pristine. The simple act of consuming more than we actually need drives the world’s governments and corporations to endlessly destroy more and more of the Earth to extract the resources necessary to satisfy our insatiable desires. In fact, an initiative of the World Economic Forum has just reported that ‘For the first time in history, more than 100 billion tonnes of materials are entering the global economy every year’ – see ‘The Circularity Gap Report 2020’– which means that, on average, every person on Earth uses more than 13 tonnes of materials each year extracted from the Earth. [...]"

Source: GlobalReasearch

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Anoxic metabolism after the 21st century in oxygen minimum zones


"Global models project a decrease of marine oxygen over the course of the 21th century. The future of marine oxygen becomes increasingly uncertain further into the future after yr 2100 , partly because ocean models differ in the way organic matter remineralisation continues under oxygen- and nitrate-free conditions. Using an Earth system model of intermediate complexity we found that under a business-as-usual CO2-emission scenario ocean deoxygenation further intensifies for several centuries until eventually ocean circulation re-establishes and marine oxygen increases again. (Oschlies et al. 2019, DOI 10.1038/s41467-019-10813-w). [...]"

Source: EGU General Assembly 2020
Authors: Wolfgang Koeve and Angela Landolfi
DOI: 10.5194/egusphere-egu2020-13038

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Effects of hypoxia on the behavior and physiology of kelp forest fishes


"Forecasts from climate models and oceanographic observations indicate increasing deoxygenation in the global oceans and an elevated frequency and intensity of hypoxic events in the coastal zone, which have the potential to affect marine biodiversity and fisheries. Exposure to low dissolved oxygen (DO) conditions may have deleterious effects on early life stages in fishes.  [...]"

Source: Global Change Biology
Authors: Evan G. Mattiasen et al.
DOI: 10.1111/gcb.15076

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Multi-agency report highlights increasing signs and impacts of climate change in atmosphere, land and oceans

"New York / Geneva, 10 March 2020 - The tell-tale physical signs of climate change such as increasing land and ocean heat, accelerating sea level rise and melting ice are highlighted in a new report compiled by the World Meteorological Organization and an extensive network of partners. It documents impacts of weather and climate events on socio-economic development, human health, migration and displacement, food security and land and marine ecosystems. [...]"

Source: World Meteorological Organization (WMO)

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Uncovering diversity and metabolic spectrum of animals in dead zone sediments


"Ocean deoxygenation driven by global warming and eutrophication is a primary concern for marine life. Resistant animals may be present in dead zone sediments, however there is lack of information on their diversity and metabolism. Here we combined geochemistry, microscopy, and RNA-seq for estimating taxonomy and functionality of micrometazoans along an oxygen gradient in the largest dead zone in the world.  [...]"

Source: Communications Biology
Authors: Elias Broman et al.
DOI: 10.1038/s42003-020-0822-7

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Even fish at the bottom of the ocean can’t escape climate change

"The fish that live at the bottom of the sea are a hardy bunch. They’re adapted to handle crushing pressure, little to no sunlight, and a meager supply of food. But these otherwise gritty fish are also very sensitive to changes in the climate of the water around them, a new study suggests.

Scientists surveyed different patches of seafloor in the Gulf of California and saw that variations in temperature and oxygen levels had a huge impact on whether the fish community was thriving or sparse. In particular, the researchers found that one specific combination—warmer waters mixed with low oxygen levels—didn’t bode well for deep sea fish. This means that these creatures are likely to be vulnerable to the impacts of climate change, the researchers reported March 5 in Marine Ecology Progress Series. [...]"

Source: Popular Science

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Special issue | Ocean deoxygenation: drivers and consequences – past, present and future (BG/CP/OS inter-journal SI)

Special issue jointly organized between Biogeosciences, Climate of the Past, and Ocean Science.

"The distribution of oxygen in the ocean is controlled by physical, biogeochemical and biological processes. Both the supply and consumption of oxygen are sensitive to climate change in ways that are not fully understood. Recent observations suggest that the oxygen content of the ocean is declining (ocean deoxygenation) and the oxygen minimum zones and costal hypoxia sites are expanding with tremendous effects on the ocean’s ecosystems and living organisms. Following the EUR-OCEANS conference on “Ocean Deoxygenation” in Toulouse, France, in 2011, the 46th International Liège Colloquium on “Low Oxygen Environments in Marine, Fresh and Estuarine Waters” in 2014 and the discussion meeting of the Royal Society London on “Ocean Ventilation and Deoxygenation in a Warming World” in 2016, the purpose of the international conference on “Ocean Deoxygenation: Drivers & Consequences – Past|Present|Future” that took place in Kiel, 3–7 Sept 2018 organised by the Collaborative Research Centre 754 “Climate-Biogeochemical Interactions in the Tropical Ocean” was to − focus on the past, present and future state of oxygen in the ocean on global, regional and local scales − analyse mechanisms and feedbacks critical to identify natural and anthropogenic causes of oxygen variability − determine impacts on biogeochemical cycles and ecosystems. [...]"

The issue is closed as of 29th February 2020. The submissions are listed here.


Is there a technological solution to aquatic dead zones?

"Could pumping oxygen-rich surface water into the depths of lakes, estuaries, and coastal ocean waters help ameliorate dangerous dead zones? New work says yes, although they caution that further research would be needed to understand any possible side effects before implementing such an approach. [...]"

Source: Science Daily 

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I/Ca in epifaunal benthic foraminifera: A semi-quantitative proxy for bottom water oxygen in a multi-proxy compilation for glacial ocean deoxygenation


"The decline in dissolved oxygen in global oceans (ocean deoxygenation) is a potential consequence of global warming which may have important impacts on ocean biogeochemistry and marine ecosystems. Current climate models do not agree on the trajectory of future deoxygenation on different timescales, in part due to uncertainties in the complex, linked effects of changes in ocean circulation, productivity and organic matter respiration. [...]"

Source: Earth and Planetary Science Letters
Authors: Wanyi Lu et al.
DOI: 10.1016/j.epsl.2019.116055

Trends and decadal oscillations of oxygen and nutrients at 50 to 300 m depth in the equatorial and North Pacific


"A strong oxygen-deficient layer is located in the upper layers of the tropical Pacific Ocean and deeper in the North Pacific. Processes related to climate change (upper-ocean warming, reduced ventilation) are expected to change ocean oxygen and nutrient inventories. In most ocean basins, a decrease in oxygen (“deoxygenation”) and an increase in nutrients have been observed in subsurface layers. Deoxygenation trends are not linear and there could be multiple influences on oxygen and nutrient trends and variability. [...]"

Source: Biogeosciences
Authors: Lothar Stramma et al.
DOI: 10.5194/bg-17-813-2020

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