Constraints on Early Paleozoic deep-ocean oxygen concentrations from the iron geochemistry of the Bay of Islands ophiolite


"The deep ocean is generally considered to have changed from anoxic in the Precambrian to oxygenated by the Late Paleozoic (∼420–400 Ma) due to changes in atmospheric oxygen concentrations. When the transition occurred, that is, in the Early Paleozoic or not until the Late Paleozoic, is less well constrained. To address this, we measured Fe3+/ΣFe of volcanic rocks, sheeted dykes, gabbros, and ultramafic rocks from the Early Paleozoic (∼485 Ma) Bay of Islands (BOI) ophiolite as a proxy for hydrothermal alteration in the presence or absence of O2 derived from deep marine fluids. [...]".


Source: Geochemistry, Geophysics, Geosystems 
Authors: Daniel A. Stolper et al. 

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Hydrostatic pressure is the universal key driver of microbial evolution in the deep ocean and beyond


"Oceans cover approximately 70% of the Earth’s surface, and microbes comprise 90% of the ocean biomass and are regarded as an important ‘hidden’ driver of essential elemental cycling, such as carbon cycling, in the oceans (Karl, 2007; Salazar and Sunagawa, 2017). Although the general public – even many scientists – think of the oceans as unified, stable water systems, they contain varied environments, including extreme environments such as oxygen-deficient zones, oligotrophic open ocean, polar water regions, deep ocean[...]"


Source: Environmental Microbiology Reports
Authors: Xiang Xiao et al.
DOI: 10.1111/1758-2229.12915 

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Shedding New Light on the Nitrogen Cycle in the Dark Ocean

"Every year, the Mississippi River dumps around 1.4 million metric tons of nitrogen into the Gulf of Mexico, much of it runoff from agricultural fertilizer. This nitrogen can lead to algal blooms, which in turn deplete oxygen concentrations in the water, creating hypoxic dead zones. The nitrogen cycle is a phenomenon environmental scientists would really like to understand better. “As humans, we do put a lot of reactive nitrogen compounds into the ocean, especially in coastal regions, by…river runoff,” said Katharina Kitzinger of the Max Planck Institute for Marine Microbiology in Bremen, Germany. “It’s really crucial to understand how microbes turn over this excess nitrogen that we put into the environment. [...]”"

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Understanding the remote influences of ocean weather on the episodic pulses of particulate organic carbon flux


"The biological carbon pump has been estimated to export ∼5–15 Gt C yr−1 into the deep ocean, and forms the principal deep-sea food resource. Irregular, intense pulses of particulate organic carbon (POC) have been found to make up about one-third of the overall POC fluxes at a long-term deep-sea research station influenced by coastal upwelling of the California Current, Station M (34°50′N, 123° W, 4000 m depth). However, the drivers of these pulses have been challenging to quantify. [...]"

Source: Deep Sea Research Part II: Topical Studies in Oceanography
Authors: Henry A. Ruhl et al.
DOI: 10.1016/j.dsr2.2020.104741

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The microbiomes of deep-sea hydrothermal vents: distributed globally, shaped locally


"The discovery of chemosynthetic ecosystems at deep-sea hydrothermal vents in 1977 changed our view of biology. Chemosynthetic bacteria and archaea form the foundation of vent ecosystems by exploiting the chemical disequilibrium between reducing hydrothermal fluids and oxidizing seawater, harnessing this energy to fix inorganic carbon into biomass. [...]"

Source: Nature Reviews Microbiology
Author: Gregory J. Dick
DOI: 10.1038/s41579-019-0160-2

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


"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

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New Study in Oxygen-Deprived Black Sea Provides Insights on Future Carbon Budget

"Scientists are studying the oxygen-deprived waters of the Black Sea to help answer questions about the deepest parts of the ocean and Earth’s climate.


A new study led by researchers at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science found that even in the absence of oxygen, the chemical and biological processes occurring in the Black Sea resemble those in the oxygenated deep ocean. [...]"

Source: University of Miami Rosenstiel School of Marine & Atmospheric Science

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Species distribution modeling of deep sea sponges in the North Pacific Ocean.


"Knowledge of deep-sea species and their ecosystems is limited due to the inaccessibility of the areas and the prohibitive cost of conducting large-scale field studies. My graduate research has used predictive modeling methods to map hexactinellid sponge habitat extent in the North Pacific, as well as climate-induced changes in oceanic dissolved oxygen levels and how this will impact sponges. [...]"

Authors: Fiona Davidson
DOI: 10.7287/peerj.preprints.26815v1

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Seasonal monitoring of deep-sea megabenthos in Barkley Canyon cold seep by internet operated vehicle (IOV)


"Knowledge of the processes shaping deep-sea benthic communities at seasonal scales in cold-seep environments is incomplete. Cold seeps within highly dynamic regions, such as submarine canyons, where variable current regimes may occur, are particularly understudied. Novel Internet Operated Vehicles (IOVs), such as tracked crawlers, provide new techniques for investigating these ecosystems over prolonged periods. In this study a benthic crawler connected to the NEPTUNE cabled infrastructure operated by Ocean Networks Canada was used to monitor community changes across 60 m2 of a cold-seep area of the Barkley Canyon, North East Pacific, at ~890 m depth within an Oxygen Minimum Zone (OMZ). [...]"

Source: PLoS ONE
Authors: Carolina Doya et al.
DOI: 10.1371/journal.pone.0176917

Full article

Deep sea life faces dark future due to warming and food shortage

New study reveals negative impact of climate change, human activity, acidification and deoxygenation on ocean and its creatures


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