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Anoxic metabolism after the 21st century in oxygen minimum zones

Abstract.

"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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Intermediate water masses, a major supplier of oxygen for the eastern tropical Pacific ocean

Abstract.

"It is well known that Intermediate Water Masses (IWM) are sinking in high latitudes and ventilate the lower thermocline (500–1500 m depth). We here highlight how the IWM oxygen content and the IWM pathway along the Equatorial Intermediate Current System (EICS) towards the eastern tropical Pacific ocean are essential for the supply of oxygen to the lower thermocline and the Oxygen Minimum Zones (OMZs). [...]"

Source: Ocean Science
Authors: Olaf Duteil et al.
DOI: 10.5194/os-2020-17

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Bioaccumulation of Trace Elements in Myctophids in the Oxygen Minimum Zone Ecosystem of the Gulf of California

Abstract.

"Myctophids are key members of mesopelagic communities with a world biomass estimated at 600 million tons. They play a central role in oceanic food webs and are known to perform diel vertical migrations, crossing the thermocline and reaching the oxygen minimum zone, however, very scarce information exists on trace element content in these organisms. Therefore, the trace elemental composition (Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd and Pb) of Triphoturus mexicanus and Benthosema panamense specimens was determined. Zinc (Zn) was the most common trace element for both species, T. mexicanus presented 39.8 µg.g−1 dw and B. panamense 30.6 µg.g−1 dw. [...]"

Source: Oceans
Authors: Cátia Figueiredo et al.
DOI: 10.3390/oceans1010004

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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

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Enhanced Organic Carbon Burial in Sediments of Oxygen Minimum Zones Upon Ocean Deoxygenation

Abstract.

"Oxygen minimum zones (OMZs) in the ocean are expanding. This expansion is attributed to global warming and may continue over the next 10 to 100 kyrs due to multiple climate CO2-driven factors. The expansion of oxygen-deficient waters has the potential to enhance organic carbon burial in marine sediments, thereby providing a negative feedback on global warming. Here, we study the response of dissolved oxygen in the ocean to increased phosphorus and iron inputs due to CO2-driven enhanced weathering and increased dust emissions, respectively. [...]"

Source: Frontiers in Marine Science
Authors: Itzel Ruvalcaba Baroni et al.
DOI: 10.3389/fmars.2019.00839

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The regulation of oxygen to low concentrations in marineoxygen-minimum zones

Abstract.

"The Bay of Bengal hosts persistent, measurable, but sub-micromolar, concentrations of oxygenin its oxygen-minimum zone (OMZ). Such low-oxygen conditions are not necessarily rare in theglobal ocean and seem also to characterize the OMZ of the Pescadero Basin in the Gulf of California,as well as the outer edges of otherwise anoxic OMZs, such as can be found, for example, in theEastern Tropical North Pacific. We show here that biological controls on oxygen consumption arerequired to allow the semistable persistence of low-oxygen conditions in OMZ settings; otherwise,only small changes in physical mixing or rates of primary production would drive the OMZ betweenanoxic and oxic states with potentially large swings in oxygen concentration. [...]"

Source: Journal of Marine Research
Authors: Donald E. Canfield et al.
 

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Variability of dissolved oxygen in the Arabian Sea Oxygen Minimum Zone and its driving mechanisms

Abstract.

"The Arabian Sea hosts one of the most intense, perennial Oxygen Minimum Zones (OMZ) in the world ocean. Observations along a meridional transect at 68°E extending from 8 to 21°N showed large seasonal as well as interannual changes in the dissolved oxygen and nitrite concentrations. Unlike previous studies that used observations from the periphery of the OMZ, our observations are from its core and also allow us demarcating the southern extent of the OMZ. [...]"

Source: Journal of Marine Systems
Authors: Damodar M.Shenoy et al.
DOI: 10.1016/j.jmarsys.2020.103310 

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The regulation of oxygen to low concentrations in marine oxygen-minimum zones

Abstract.

"The Bay of Bengal hosts persistent, measurable, but sub-micromolar, concentrations of oxygen in its oxygen-minimum zone (OMZ). Such low-oxygen conditions are not necessarily rare in the global ocean and seem also to characterize the OMZ of the Pescadero Basin in the Gulf of California, as well as the outer edges of otherwise anoxic OMZs, such as can be found, for example, in the Eastern Tropical North Pacific. We show here that biological controls on oxygen consumption are required to allow the semistable persistence of low-oxygen conditions in OMZ settings; otherwise, only small changes in physical mixing or rates of primary production would drive the OMZ between anoxic and oxic states with potentially large swings in oxygen concentration. [...]"

Source: Journal of Marine Research 
Authors: Don E. Canfield et al.

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Larval Fish Habitats and Deoxygenation in the Northern Limit of the Oxygen Minimum Zone off Mexico

Abstract.

"The present state of deoxygenation in the northern limits of the shallow oxygen minimum zone off Mexico is examined in order to detect its effects on larval fish habitats and consider the sensitivity of fish larvae to decreased dissolved oxygen. A series of cruises between 2000 and 2017 indicated a significant vertical expansion of low oxygen waters. The upper limit of suboxic conditions (<4.4 μmol/kg) has risen ~100 m at 19.5°N off Cabo Corrientes and ~50 m at 25°N in the mouth of the Gulf of California. The larval habitat distribution was related to the geographic variability of dissolved oxygen and water masses between these two latitudes. [...]"

Source: JGR Oceans
Authors: Laura Sánchez‐Velasco et al.
DOI: 10.1029/2019JC015414

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Multidisciplinary Observing in the World Ocean’s Oxygen Minimum Zone Regions: From Climate to Fish — The VOICE Initiative

Abstract.

"Multidisciplinary ocean observing activities provide critical ocean information to satisfy ever-changing socioeconomic needs and require coordinated implementation. The upper oxycline (transition between high and low oxygen waters) is fundamentally important for the ecosystem structure and can be a useful proxy for multiple observing objectives connected to eastern boundary systems (EBSs) that neighbor oxygen minimum zones (OMZs). [...]"

Source: Frontiers in Marine Science
Authors: Véronique Garçon et al.
DOI: 10.3389/fmars.2019.00722

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