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Editorial: Recent developments in oxygen minimum zones biogeochemistry

Abstract.

"Marine Oxygen Minimum Zones (OMZs) modulate biogeochemical cycles, and directly impact climate dynamics by influencing air-sea fluxes of the potent greenhouse gases methane and nitrous oxide (Levin, 2018). OMZs are formed in regions of weak oxygen (O2) supply from physical ventilation and high integrated microbial O2 demand fueled by downward organic flux from overlying surface waters. The ocean’s major OMZs are found in the Eastern Tropical South and North Pacific Ocean and the Arabian Sea and Bay of Bengal in the Indian Ocean (Karstensen et al., 2008; Stramma et al., 2008). [...]".

 

Source: Frontiers in Marine Science
Authors: Annie Bourbonnais et al.
DOI: https://doi.org/10.3389/fmars.2023.1333731

Read the full article here.


Partitioning of the denitrification pathway and other nitrite metabolisms within global oxygen deficient zones

Abstract.

"Oxygen deficient zones (ODZs) account for about 30% of total oceanic fixed nitrogen loss via processes including denitrification, a microbially mediated pathway proceeding stepwise from NO3– to N2. This process may be performed entirely by complete denitrifiers capable of all four enzymatic steps, but many organisms possess only partial denitrification pathways, either producing or consuming key intermediates such as the greenhouse gas N2O. Metagenomics and marker gene surveys have revealed a diversity of denitrification genes within ODZs, but whether these genes co-occur within [...]".

 

Source: Nature
Authors: Irene H. Zhang et al.
DOI: https://doi.org/10.1038/s43705-023-00284-y

Read the full article here.


A hydrogenotrophic Sulfurimonas is globally abundant in deep-sea oxygen-saturated hydrothermal plumes

Abstract. 

"Members of the bacterial genus Sulfurimonas (phylum Campylobacterota) dominate microbial communities in marine redoxclines and are important for sulfur and nitrogen cycling. Here we used metagenomics and metabolic analyses to characterize a Sulfurimonasfrom the Gakkel Ridge in the Central Arctic Ocean and Southwest Indian Ridge, showing that this species is ubiquitous in non-buoyant hydrothermal plumes at Mid Ocean Ridges across the global ocean. One Sulfurimonas species, USulfurimonas pluma, was found to be globally abundant and active in cold (<0−4 °C), oxygen-saturated and hydrogen-rich hydrothermal plumes. [...]".

 

Source: Nature
Authors: Massimiliano Molari et al.
DOI: https://doi.org/10.1038/s41564-023-01342-w

Read the full article here.


Insights into prokaryotic community and its potential functions in nitrogen metabolism in the Bay of Bengal, a pronounced Oxygen Minimum Zone

Abstract. 

"Ocean oxygen minimum zones (OMZs) around the global ocean are expanding both horizontally and vertically. Multiple studies have identified the significant influence of anoxic conditions (≤1 μM O2) on marine prokaryotic communities and biogeochemical cycling of elements. However, little attention has been paid to the expanding low-oxygen zones where the oxygen level is still above the anoxic level. Here, we studied the abundance and taxonomic and functional profiles of prokaryotic communities in the Bay of Bengal (BoB), where the oxygen concentration is barely above suboxic level (5 μM O2). [...]". 

 

Source: Microbiology Spectrum
Authors: Bowei Gu et al. 
DOI: https://doi.org/10.1128/spectrum.00892-21

Read the full article here.


Biotic induction and microbial ecological dynamics of Oceanic Anoxic Event 2

Abstract. 

"Understanding the causal mechanisms of past marine deoxygenation is critical to predicting the long-term Earth systems response to climate change. However, the processes and events preceding widespread carbon burial coincident with oceanic anoxic events remain poorly constrained. Here, we report a comprehensive biomarker inventory enveloping Oceanic Anoxic Event 2 that captures microbial communities spanning epipelagic to benthic environments in the southern proto-North Atlantic Ocean. We identify an abrupt, sustained increase in primary productivity that predates Oceanic Anoxic Event 2 by ∼220 ± 4 thousand years, well before other geochemical proxies register biogeochemical perturbations. [...]". 

 

Source: Communications Earth & Environment 
Authors: Gregory T. Connock et al. 
DOI: https://doi.org/10.1038/s43247-022-00466-x 

Read the full article here.


Small phytoplankton contribute greatly to CO2-fixation after the diatom bloom in the Southern Ocean

Abstract.

"Phytoplankton is composed of a broad-sized spectrum of phylogenetically diverse microorganisms. Assessing CO2-fixation intra- and inter-group variability is crucial in understanding how the carbon pump functions, as each group of phytoplankton may be characterized by diverse efficiencies in carbon fixation and export to the deep ocean. We measured the CO2-fixation of different groups of phytoplankton at the single-cell level around the naturally iron-fertilized Kerguelen plateau (Southern Ocean)[...]"

 

Source: The ISME Journal 
Authors: Solène Irion et al
DOI: https://doi.org/10.1038/s41396-021-00915-z

Read the full article here.


Fishing trawlers could harm water quality by disrupting seafloor microbes

"Fishing boats that drag nets along the sea floor to catch seafood can indiscriminately harm marine life and destroy habitat. Now, a new study suggests “bottom trawling” can also disrupt the ability of microbes in sediment to remove excess nutrients in coastal waters, potentially increasing that pollution. “This is one of the first papers to look at actual biogeochemical effects of bottom trawling,” says Sebastiaan van de Velde, a marine biogeochemist at the University of California, Riverside, who was not involved. “The whole angle is very novel.” [...]"

Source: Science

Read the full article here.


Discovery and Mapping of the Triton Seep Site, Redondo Knoll: Fluid Flow and Microbial Colonization Within an Oxygen Minimum Zone

Abstract.

"This paper examines a deep-water (∼900 m) cold-seep discovered in a low oxygen environment ∼30 km off the California coast in 2015 during an E/V Nautilus telepresence-enabled cruise. This Triton site was initially detected from bubble flares identified via shipboard multibeam sonar and was then confirmed visually using the remotely operated vehicle (ROV) Hercules. High resolution mapping (to 1 cm resolution) and co-registered imaging has provided us with a comprehensive site overview – both of the geologic setting and the extent of the associated microbial colonization. [...]"

Source: Frontiers in Marine Science
Authors: Jamie K. S. Wagner et al.
DOI: 10.3389/fmars.2020.00108

Read the full article here.


Interactions of anaerobic ammonium oxidizers and sulfide-oxidizing bacteria in a substrate-limited model system mimicking the marine environment

Abstract. 

"In nature anaerobic ammonium oxidation (anammox) and denitrification processes convert fixed nitrogen to gaseous nitrogen compounds, which are then released to the atmosphere. While anammox bacteria produce N2 from ammonium and nitrite, in the denitrification process nitrate and nitrite are converted to N2 and the greenhouse gas nitrous oxide (N2O). [...]"

Source: FEMS Microbiology Ecology
Authors: Lina Russ et al. 
DOI: 10.1093/femsec/fiz137

Read the full article here.


Diversity and relative abundance of ammonia- and nitrite-oxidizing microorganisms in the offshore Namibian hypoxic zone

Abstract.

"Nitrification, the microbial oxidation of ammonia (NH3) to nitrite (NO2) and NO2 to nitrate (NO3), plays a vital role in ocean nitrogen cycling. Characterizing the distribution of nitrifying organisms over environmental gradients can help predict how nitrogen availability may change with shifting ocean conditions, for example, due to loss of dissolved oxygen (O2). [...]"

Source: PLoS ONE
Authors: Evan Lau et al.
DOI: 10.1371/journal.pone.0217136

Read the full article here.


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