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Marine ammonification and carbonic anhydrase activity induce rapid calcium carbonate precipitation

Abstract.

"During Earth’s history, precipitation of calcium carbonate by heterotrophic microbes has substantially contributed to the genesis of copious amounts of carbonate sediment and its subsequent lithification. Previous work identified the microbial sulfur and nitrogen cycle as principal pathways involved in the formation of marine calcium carbonate deposits. While substantial knowledge exists for the importance of the sulfur cycle, specifically sulfate reduction, with regard to carbonate formation, information about carbonate genesis connected to the microbial nitrogen cycle is dissatisfactory. [...]"

Source: Geochimica et Cosmochimica Acta
Authors: S. Krause et al
DOI: 10.1016/j.gca.2018.09.018

Read the full article here.


Spatial congruence between multiple stressors in the Mediterranean Sea may reduce its resilience to climate impacts

Abstract.

"Climate impacts on marine ecosystems may be exacerbated by other, more local stressors interacting synergistically, such as pollution and overexploitation of marine resources. The reduction of these human stressors has been proposed as an achievable way of retaining ecosystems within a “safe operating space” (SOS), where they remain resilient to ongoing climate change. However, the operability of an SOS requires a thorough understanding of the spatial distribution of these climate and human impacts. [...]"

Source: Scientific Reports
Authors: Francisco Ramírez et al.
DOI: 10.1038/s41598-018-33237-w

Read the full article here.


Deep-Water Dynamics in the Subpolar North Atlantic at the End of the Quaternary

Abstract.

"In the subpolar North Atlantic, four sediment cores were taken. All of them were suitable for reconstructing the dynamics of the meridional overturning circulation in the late Quaternary. Stratigraphy of the cores was performed by carbonate analyses, study of planktonic foraminifera, and oxygen isotopic composition in Neogloboquadrina pachyderma sin. Study of benthonic foraminifera assemblages has shown significant differences in the deep-water dynamics in the late Quaternary related to water exchange between the North Atlantic and Arctic seas. [...]"

Source: Oceanology
Authors: N.P. Lukashina
DOI: 10.1134/S0001

Read the full article here.


Photosynthesis by marine algae produces sound, contributing to the daytime soundscape on coral reefs

Abstract.

"We have observed that marine macroalgae produce sound during photosynthesis. The resultant soundscapes correlate with benthic macroalgal cover across shallow Hawaiian coral reefs during the day, despite the presence of other biological noise. Likely ubiquitous but previously overlooked, this source of ambient biological noise in the coastal ocean is driven by local supersaturation of oxygen near the surface of macroalgal filaments, and the resultant formation and release of oxygen-containing bubbles into the water column. During release, relaxation of the bubble to a spherical shape creates a monopole sound source that ‘rings’ at the Minnaert frequency. [...]"

Source: PLOS ONE
Authors: Simon E. Freeman et al.
DOI: 10.1371/journal.pone.0201766

Read the full article here.


GO2NE Summer School 2019

The IOC- GO2NE SS2019: The Global Ocean Oxygen Network (GO2NE) from the UNESCO Intergovernmental Oceanographic Commission (IOC-UNESCO) organizes an international Summer School that will be held from September 2 to 8, 2019 in China on Xiamen University Xiang’an Campus which hosts the State Key Laboratory of Marine Environmental Science.

The IOC- GO2NE SS2019 will bring together 40 PhD students and early career scientists with 16 world-leading international scientists. It aims to connect young researchers with leading scientists from the academic and SMEs world working on oxygen not only in a theoretical framework, but also through practical sessions on laboratory experiments, field work, modelling and special sessions on communication, ethics, and engagement with stakeholder (see “Program”). 

The IOC-GO2NE vision is to provide scientific knowledge and educate the young generation of scientists for ‘the Ocean we need for the Future we want’ (IOC-UNESCO brochure – International Decade of Ocean Science for Sustainable Development’).

Follow this link to register on the official homepage.


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Last interglacial ocean changes in the Bahamas: climate teleconnections between low and high latitudes

Abstract.

"Paleorecords and modeling studies suggest that instabilities in the Atlantic Meridional Overturning Circulation (AMOC) strongly affect the low-latitude climate, namely via feedbacks on the Atlantic Intertropical Convergence Zone (ITCZ). Despite the pronounced millennial-scale overturning and climatic variability documented in the subpolar North Atlantic during the last interglacial period (MIS 5e), studies on cross-latitudinal teleconnections remain very limited. This precludes a full understanding of the mechanisms controlling subtropical climate evolution across the last warm cycle. [...]"

Source: Climate of the Past
Authors: Anastasia Zhuravleva and Henning A. Bauch
DOI: 10.5194/cp-14-1361-2018

Read the full article here.


Redox condition and nitrogen cycle in the Permian deep mid-ocean: A possible contrast between Panthalassa and Tethys

Abstract.

"To constrain the redox conditions and related nitrogen cycles during the Middle Permian (Guadalupian) to latest Late Permian (Lopingian) deep mid-Panthalassa, we determined the abundances of major, trace, and rare earth elements along with the carbon and nitrogen isotope ratios in shales interbedded with deep-sea cherts that are well-exposed at the Gujo-Hachiman section in the Mino-Tanba belt, SW Japan. [...]"

Source: Global and Planetary Change
Authors: Wataru Fujisaki et al.
DOI: 10.1016/j.gloplacha.2018.09.015

Read the full article here.


Projected Centennial Oxygen Trends and Their Attribution to Distinct Ocean Climate Forcings

Abstract.

"We explore centennial changes in tropical Pacific oxygen (O2) using numerical models to illustrate the dominant patterns and mechanisms under centennial climate change. Future projections from state‐of‐the‐art Earth System Models exhibit significant model to model differences, but decreased solubility and weakened ventilation together deplete thermocline O2 in middle to high latitudes. In contrast, the tropical thermocline O2undergoes much smaller changes or even a slight increase. [...]"

Source: Global Biogeochemical Cycles
Authors: Yohei Takano, Takamitsu Ito & Curtis Deutsch
DOI: 10.1029/2018GB005939

Read the full article here.


Microbial niches in marine oxygen minimum zones

Abstract.

"In the ocean’s major oxygen minimum zones (OMZs), oxygen is effectively absent from sea water and life is dominated by microorganisms that use chemicals other than oxygen for respiration. Recent studies that combine advanced genomic and chemical detection methods are delineating the different metabolic niches that microorganisms can occupy in OMZs. Understanding these niches, the microorganisms that inhabit them, and their influence on marine biogeochemical cycles is crucial as OMZs expand with increasing seawater temperatures."

Source: Nature Reviews Microbiology
Authors: Anthony D. Bertagnolli & Frank J. Stewart
DOI: 10.1038/s41579-018-0087-z

Read the full article here.


Drivers of oxygen consumption in the northern Gulf of Mexico hypoxic waters – A stable carbon isotope perspective

Abstract.

"We examined the stable carbon isotopic composition of remineralized organic carbon (δ13COCx) in the northern Gulf of Mexico (nGoM) using incubations (sediment and water) and a three end‐member mixing model. δ13COCx in incubating sediments was ‐18.1±1.3‰, and δ13COCx in incubating near‐surface and near‐bottom waters varied with salinity, ranging from ‐30.4‰ to ‐16.2‰ from brackish water to full strength Gulf water. The average δ13COCx was ‐18.6 ±1.8‰ at salinity >23. A three end‐member mixing model based on a multi‐year dataset collected in previous summer hypoxia cruises (2011, 2012, 2014, 2015 and 2016) suggested that δ13COCx in near‐bottom waters across the nGoM (5‐50 m) was ‐18.1±0.6‰. [...]" 

Source: Geophysical Reasearch Letters
Authors: Hongjie Wang et al.
DOI: 10.1029/2018GL078571

Read the full article here.


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