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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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Slaking the world’s thirst with seawater dumps toxic brine in oceans

"Growing populations and tightening water supplies have spurred people in many places—including the Middle East, Australia, California and China—to look to the oceans and other salty waters as a source of new drinking water. But desalination plants are energy intensive and create a potentially environment-harming waste called brine (made up of concentrated salt and chemical residues), which is dumped into the ocean, injected underground or spread on land.

Despite the ecological threats, “there was no comprehensive assessment about brine—how much we produce,” says Manzoor Qadir, assistant director of the United Nations University Institute on Water, Environment and Health. So he and his colleagues calculated that figure and found it is 50 percent greater than the desalination industry’s previous rough estimate. In fact, it is enough to cover Florida with 30 centimeters of brine every year. [...]"

Source: Scientific American

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Planktonic food web structure and trophic transfer efficiency along a productivity gradient in the tropical and subtropical Atlantic Ocean

Abstract.

"Oligotrophic and productive areas of the ocean differ in plankton community composition and biomass transfer efficiency. Here, we describe the plankton community along a latitudinal transect in the tropical and subtropical Atlantic Ocean. Prochlorococcus dominated the autotrophic community at the surface and mixed layer of oligotrophic stations, replaced by phototrophic picoeukaryotes and Synechococcus in productive waters. [...]"

Source: Scientific Reports
Authors: Laia Armengol et al.
DOI: 10.1038/s41598-019-38507-9

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Variability of seawater chemistry in a kelp forest environment is linked to in situ transgenerational effects in the purple sea urchin

Abstract.

"While the value of giant kelp (Macrocystis pyrifera) as a habitat-forming foundation species is well-understood, it is unclear how they impact the oxygen concentration and pH of the surrounding seawater, and further, how such a dynamic abiotic environment will affect eco-evolutionary dynamics in a context of global change. Here, we profiled the nearshore kelp forest environment in Southern California to understand changes in dissolved oxygen (DO) and pH with high spatiotemporal resolution. We then examined transgenerational effects using sea urchins (Strongylocentrotus purpuratus) as our study organism.  [...]"

Source: Frontiers in Marine Science
Authors: Umihiko Hoshijima and Gretchen Hofmann
DOI: 10.3389/fmars.2019.00062

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Deep‐sea oxygen depletion and ocean carbon sequestration during the last ice age

Abstract.

"Enhanced ocean carbon storage during the Pleistocene ice ages lowered atmospheric CO2 concentrations by 80 to 100 ppm relative to interglacial levels. Leading hypotheses to explain this phenomenon invoke a greater efficiency of the ocean's biological pump, in which case carbon storage in the deep sea would have been accompanied by a corresponding reduction in dissolved oxygen. We exploit the sensitivity of organic matter preservation in marine sediments to bottom water oxygen concentration to constrain the level of dissolved oxygen in the deep central equatorial Pacific Ocean during the last glacial period (18,000 – 28,000 years BP) to have been within the range of 20‐50 μmol/kg, much less than modern value of ca. 168 μmol/kg. [...]"

Source: Global Biogeochemical Cycles
Authors: Robert F. Anderson et al.
DOI: 10.1029/2018GB006049

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Effects of Coastal Upwelling and Downwelling on Hydrographic Variability and Dissolved Oxygen in Mobile Bay

Abstract.

"Upwellling and downwelling events are important coastal processes that strongly influence shelf ecosystem dynamics. Though changes on the shelf have been well studied, the impact of these events on estuarine systems has received less focus. In summer 2016 a downwelling and upwelling event were observed near the mouth of Mobile Bay. The impact of these events were examined throughout the bay with high spatial resolution observations. Five boat surveys were conducted to capture the spatial response of offshore forcing and its changes in the estuary. In addition to the surveys, 16 CTDs were deployed and measured temporal changes. [...]"

Source: JGR Oceans
Authors: Jeffrey Coogan, Brian Dzwonkowski and John Lehrter
DOI: 10.1029/2018JC014592

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Study of dissolved oxygen responses to tropical cyclones in the Bay of Bengal based on Argo and satellite observations

Abstract.

"Effects of tropical cyclones (TCs) on dissolved oxygen (DO) in subsurface waters (20–200 m) over the Oxygen Minimum Zones (OMZs) in the Bay of Bengal (BoB) are examined based on Argo and satellite data. Five TCs (Hudhud, Five, Vardah, Maarutha and Mora) during 2013–2018 are considered. Analyses reveal three types of DO temporal variability caused by the storm-induced mixing and upwelling. The first type features temporal DO increases in subsurface waters (37–70 m) caused mainly by intense vertical mixing and downwelling. [...]"

Source: Science of the Total Environment
Authors: Huabing Xu et al.
DOI: 10.1016/j.scitotenv.2018.12.384

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A Novel Approach for Measuring the Gulf of Mexico Dead Zone: Toward Better Temporal and Spatial Estimates for Management Applications

Abstract.

"Nearly every summer, a large hypoxic zone forms in the northern Gulf of Mexico. Research on the causes and consequences of hypoxia requires reliable estimates of hypoxic extent, which can vary at submonthly time scales due to hydro-meteorological variability. Here, we use an innovative space-time geostatistical model and data collected by multiple research organizations to estimate bottom-water dissolved oxygen (BWDO) concentrations and hypoxic area across summers from 1985 to 2016. [...]"

Source: Environmental Science and Technology 
Authors: V. Rohith Reddy Matli et al.
DOI: 10.1021/acs.est.8b03474

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