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Exploring the Susceptibility of Turbid Estuaries to Hypoxia as a Prerequisite to Designing a Pertinent Monitoring Strategy of Dissolved Oxygen

Abstract.

"Globally, there has been a decrease in dissolved oxygen in the oceans, that is more pronounced in coastal waters, resulting in more frequent hypoxia exposure for many marine animals. Managing hypoxia requires an understanding of the dynamics of dissolved oxygen (DO) where it occurs. The French coast facing the Bay of Biscay (N-E Atlantic Ocean) hosts at least a dozen tidal and turbid estuaries, but only the large estuaries of the Gironde and the Loire, are subject to a continuous monitoring. [...]"

Source: Frontiers in Marine Science 
Authors: Sabine Schmidt et al.
DOI: 10.3389/fmars.2019.00352

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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

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Diapycnal dissolved organic matter supply into the upper Peruvian oxycline

Abstract.

"The eastern tropical South Pacific (ETSP) hosts the Peruvian upwelling system, which represents one of the most productive areas in the world ocean. High primary production followed by rapid heterotrophic utilization of organic matter supports the formation of one of the most intense oxygen minimum zones (OMZs) in the world ocean, where dissolved oxygen (O2) concentrations reach less than 1 µmol kg−1. [...]"

Source: Biogeosciences
Authors: Alexandra N. Loginova et al.
DOI: 10.5194/bg-16-2033-2019

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Periodic changes in the Cretaceous ocean and climate caused by marine redox see-saw

Abstract.

"Periodic changes in sediment composition are usually ascribed to insolation forcing controlled by Earth’s orbital parameters. During the Cretaceous Thermal Maximum at 97–91 Myr ago (Ma), a 37–50-kyr-long cycle that is generally believed to reflect obliquity forcing dominates the sediment record.  [...]"

Source: Nature Geoscience
Authors: Klaus Wallmann et al.
DOI: 10.1038/s41561-019-0359-x

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Discrepancy in the Identification of the Atlantic/Pacific Front in the Central Arctic Ocean: NO Versus Nutrient Relationships

Abstract.

"Fronts in the NO parameter, a semiconservative tracer combining nitrate and dissolved oxygen, and dynamic height were observed in the central East Siberian Sea that distinguished Atlantic and Pacific contributions to the upper halocline of the Amerasian Basin during the summer of 2015. [...]"

Source: Geophysical Research Letters
Authors: Matthew B. Alkire, Robert Rember and Igor Polyakov
DOI: 10.1029/2018GL081837

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An assessment of the predictability of column minimum dissolved oxygen concentrations in Chesapeake Bay using a machine learning model

Abstract.

"Subseasonal to seasonal forecasts have the potential to be a useful tool for managing estuarine fisheries and water quality, and with increasing skill at forecasting conditions at these time scales in the atmosphere and open ocean, skillful forecasts of estuarine salinity, temperature, and biogeochemistry may be possible. In this study, we use a machine learning model to assess the predictability of column minimum dissolved oxygen in Chesapeake Bay at a monthly time scale. [...]"

Source: Estuarine, Coastal and Shelf Science
Authors: Andrew C. Ross, Charles A. Stock
DOI: 10.1016/j.ecss.2019.03.007

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Seasonal and sub-seasonal oxygen and nutrient fluctuations in an embayment of an eastern boundary upwelling system: St Helena Bay

Abstract.

"Seasonal, sub-seasonal and spatial fluctuations in bottom dissolved oxygen (DO) were examined in St Helena Bay, South Africa’s largest and most productive embayment, between November 2013 and November 2014. Alongshore bay characteristics were assessed through comparison of variables along the 50-m depth contour. A mean coefficient of variation of 0.35 provided a measure of the relative variability of near-bottom DO concentrations along this contour. Consistently lower DO concentrations in the southern region of the bay in summer and autumn are attributed to enhanced retention. [...]"

Source: African Journal of Marine Science (2017)
Authors: GC Pitcher & TA Probyn
DOI: 10.2989/1814232X.2017.1305989

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Uncovering mechanisms of global ocean change effects on the Dungeness crab (Cancer magister) through metabolomics analysis

Abstract.

"The Dungeness crab is an economically and ecologically important species distributed along the North American Pacific coast. To predict how Dungeness crab may physiologically respond to future global ocean change on a molecular level, we performed untargeted metabolomic approaches on individual Dungeness crab juveniles reared in treatments that mimicked current and projected future pH and dissolved oxygen conditions. We found 94 metabolites and 127 lipids responded in a condition-specific manner, with a greater number of known compounds more strongly responding to low oxygen than low pH exposure. [...]"

Source: bioRxiv
Authors: Shelly A. Trigg et al.
DOI: 10.1101/574798

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Seasonal Variability of the Mauritania Current and Hydrography at 18°N

Abstract.

"Extensive field campaigns in the Mauritanian upwelling region between 2005 and 2016 provide the database for analyzing the seasonal variability of the eastern boundary circulation (EBC) and associated water mass distribution at 18°N. The data set includes shipboard upper ocean current, hydrographic, and oxygen measurements from nine research cruises conducted during upwelling (December to April) and relaxation (May to July) seasons. [...]"

Source: JGR Oceans
Authors: T. Klenz, M. Dengler and P. Brandt
DOI: 10.1029/2018JC014264

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Autonomous profiling float observations reveal the dynamics of deep biomass distributions in the denitrifying oxygen minimum zone of the Arabian Sea

Abstract.

"Data from 13 autonomous profiling BGC-Argo floats, equipped with biogeochemical and bio-optical sensors deployed between 2011 and 2016, were used to explore the potential of bio-optical methods to map deep biomass distribution in the Arabian Sea oxygen minimum zone (OMZ). Dissolved oxygen sensors revealed concentrations below 5 μmol kg−1 for much of the depth range between 200 and 400 m and below 1 μmol kg−1 in the centre of the OMZ, which is well below climatological values. [...]"

Source: Journal of Marine Systems
Authors: Bożena Wojtasiewicz et al.
DOI: 10.1016/j.jmarsys.2018.07.002

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