Large-scale ocean deoxygenation during the Paleocene-Eocene Thermal Maximum
"The consequences of global warming for fisheries are not well understood, but the geological record demonstrates that carbon cycle perturbations are frequently associated with ocean deoxygenation. Of particular interest is the Paleocene-Eocene Thermal Maximum (PETM) where the CO2 input into the atmosphere was similar to the IPCC RCP8.5 emission scenario. Here we present sulfur-isotope data which record a positive 1 ‰ excursion during the PETM. Modeling suggests that significant parts of the ocean must have become sulfidic. The toxicity of hydrogen sulfide will render two of the largest and least explored ecosystems on Earth, the mesopelagic and bathypelagic zones, uninhabitable by multi-cellular organisms. This will affect many marine species whose eco-zones stretch into the deep ocean. [...]"
Authors: Weiqi Yao, Adina Paytan, Ulrich G. Wortmann
Macrobenthic communities in a shallow normoxia to hypoxia gradient in the Humboldt upwelling ecosystem
"Hypoxia is one of the most important stressors affecting the health conditions of coastal ecosystems. In highly productive ecosystems such as the Humboldt Current ecosystem, the oxygen minimum zone is an important abiotic factor modulating the structure of benthic communities over the continental shelf. Herein, we study soft-bottom macrobenthic communities along a depth gradient–at 10, 20, 30 and 50 m–for two years to understand how hypoxia affects the structure of shallow communities at two sites in Mejillones Bay (23°S) in northern Chile. [...]"
Source: PLoS ONE
Authors: Maritza Fajardo et al.
Expanding 'dead zone' in Arabian Sea raises climate change fears
In the waters of the Arabian Sea, a vast "dead zone" the size of Scotland is expanding and scientists say climate change may be to blame. In his lab in Abu Dhabi, Zouhair Lachkar is labouring over a colourful computer model of the Gulf of Oman, showing changing temperatures, sea levels and oxygen concentrations.His models and new research unveiled earlier this year show a worrying trend.Dead zones are areas of the sea where the lack of oxygen makes it difficult for fish to survive and the one in the Arabian Sea is "is the most intense in the world," says Lachkar, a senior scientist at NYU Abu Dhabi in the capital of the United Arab Emirates.
The Ocean is losing its breath: declining oxygen in the world's ocean and coastal waters; summary for policy makers
"Oxygen is critical to the health of the ocean. It structures aquatic ecosystems, impacts the biogeochemical cycling of carbon, nitrogen and other key elements, and is a fundamental requirement for marine life from the intertidal zone to the greatest depths of the ocean." [...]
Source: UNESCO (UNESDOC)
Authors: Denise Breitburg et al.
How ocean warmth triggers glacial melting far away
"The melting of glaciers on one side of the globe can trigger disintegration of glaciers on the other side of the globe, as has been presented in a recent paper by a team of AWI scientists, who investigated marine microalgae preserved in glacial deposits and subsequently used their findings to perform climate simulations. The study highlights a process with alerting consequences for modern ice sheets: continuous warming of the ocean can result in a massive loss of polar ice mass, and consequently to rapid sea level rise."
Source: Science Daily
North Pacific freshwater events linked to changes in glacial ocean circulation
"There is compelling evidence that episodic deposition of large volumes of freshwater into the oceans strongly influenced global ocean circulation and climate variability during glacial periods. In the North Atlantic region, episodes of massive freshwater discharge to the North Atlantic Ocean were related to distinct cold periods known as Heinrich Stadials. [...]"
Authors: E. Maier et al.
2018 AGU Fall Meeting
The Fall Meeting 2018 is a unique opportunity to highlight the latest discoveries, insights, and advances for our global community of Earth and space scientists, and at the same time to raise appreciation of the value and impact of our science among world leaders in Washington, D.C.
The 2018 meeting also marks the beginning of AGU’s Centennial in 2019, a time to reflect on the meaning of a century of discovery and to look ahead to the essential contributions that our science will make to understanding our world, informing policy decisions, sparking innovation, and protecting the health and welfare of people everywhere.
- Session Proposal and Tutorial Talk Acceptance Notifications: mid-June 2018
- Early abstract submission deadline: 25 July 2018, 11:59 PM EDT
- Abstract and Town Hall Submission Deadline: 1 August 2018, 11:59 PM EDT
- Scientific Program Released and Abstract and Sessions’ Scheduled Days/Times Notifications Sent: 1 October 2018
Get more information about the meeting on the official homepage.
Start Date: 12/9/18
2018 AGU Fall Meeting
Conveners: Jim Ammerman/Long Island Sound Study, and Jim O'Donnell/University of Connecticut
Single cell genomic and transcriptomic evidence for the use of alternative nitrogen substrates by anammox bacteria
"Anaerobic ammonium oxidation (anammox) contributes substantially to ocean nitrogen loss, particularly in anoxic marine zones (AMZs). Ammonium is scarce in AMZs, raising the hypothesis that organic nitrogen compounds may be ammonium sources for anammox. Biochemical measurements suggest that the organic compounds urea and cyanate can support anammox in AMZs. [...]"
Source: The ISME Journal
Authors: Sangita Ganesh et al.
Early Palaeozoic ocean anoxia and global warming driven by the evolution of shallow burrowing
"The evolution of burrowing animals forms a defining event in the history of the Earth. It has been hypothesised that the expansion of seafloor burrowing during the Palaeozoic altered the biogeochemistry of the oceans and atmosphere. However, whilst potential impacts of bioturbation on the individual phosphorus, oxygen and sulphur cycles have been considered, combined effects have not been investigated, leading to major uncertainty over the timing and magnitude of the Earth system response to the evolution of bioturbation. [...]"
Source: Nature Communications
Authors: Sebastiaan van de Velde et al.