Source: Springer Link
Authors: Cassandra N. Glaspie et al.
DOI: 10.1007/s12237-019-00626-x

Abstract

"The occurrence of low dissolved oxygen (hypoxia) in coastal waters may alter trophic interactions within the water column. This study identified a threshold at which hypoxia in the northern Gulf of Mexico (NGOMEX) alters composition of fish catch and diet composition (stomach contents) of fishes using fish trawl data from summers 2006–2008. Hypoxia in the NGOMEX impacted fish catch per unit effort (CPUE) and diet below dissolved oxygen thresholds of 1.15 mg L⁻¹ (for fish CPUE) and 1.71 mg L⁻¹ (for diet). CPUE of many fish species was lower at hypoxic sites (≤ 1.15 mg L ⁻¹) as compared to normoxic regions (> 1.15 mg L ⁻¹), including the key recreational or commercial fish species Atlantic croaker Micropogonias undulatus and red snapper Lutjanus campechanus. [...]."

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Source: Wiley Online Library
Authors: Laura Sánchez‐Velasco et al.
DOI: 10.1029/2019JC015414

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. [...]."

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Source: Nature
Authors: L. Resplandy et al.
DOI: 10.1038/s41598-019-56490-z

Abstract

"The ocean is the main source of thermal inertia in the climate system. Ocean heat uptake during recent decades has been quantified using ocean temperature measurements. However, these estimates all use the same imperfect ocean dataset and share additional uncertainty due to sparse coverage, especially before 2007. Here, we provide an independent estimate by using measurements of atmospheric oxygen (O₂) and carbon dioxide (CO₂) – levels of which increase as the ocean warms and releases gases – as a whole ocean thermometer. [...]."

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Source: Journal of Marine Research
Authors: Donald E. Canfield et al.
DOI: 10.1357/002224019828410548

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. [...]."

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Source: Frontiers in Environmental Science
Authors: Gretchen J. McCarthy et al.
DOI: 10.3389/fenvs.2019.00194

Abstract

"Non-native species introductions are associated with a range of ecosystem changes such as habitat destruction, competition with native species, and biodiversity losses. Less well known is the role non-native species play in altering biogeochemical processes, such as the emission of greenhouse gases (GHGs). In this study we used laboratory incubations to compare seasonal (spring, summer, fall) emissions of the GHGs nitrous oxide (N₂O), methane (CH₄), and carbon dioxide (CO₂) from native (Crassostrea virginica) and non-native (Ostrea edulis) oysters collected from a northern temperate estuary (Duxbury Bay, Massachusetts, USA). [...]."

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Source: Nature 
Authors: Arjen Tilstra et al.
DOI: 10.1038/s41598-019-55408-z

Abstract

"Denitrification may potentially alleviate excess nitrogen (N) availability in coral holobionts to maintain a favourable N to phosphorous ratio in the coral tissue. However, little is known about the abundance and activity of denitrifiers in the coral holobiont. The present study used the nirS marker gene as a proxy for denitrification potential along with measurements of denitrification rates in a comparative coral taxonomic framework from the Red Sea: Acropora hemprichii, Millepora dichotoma, and Pleuractis granulosa. [...]."

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Source: Science Daily

"In recent years, scientists have projected increasingly large summer dead zones in the Chesapeake Bay, areas where there is little or no oxygen for living things like crabs and fish to thrive, even as long-term efforts to reduce nutrient pollution continue. Researchers factored in local impacts of climate change to make projections of what the oxygen content of the Chesapeake Bay will look like in the future. [...]."

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Source: Wiley Online Library
Authors: Jiangsi Liu et al.
DOI: 10.1029/2019GC008614

Abstract

"The end‐Devonian mass extinction (~359 Ma) substantially impacted marine ecosystems and shaped the roots of modern vertebrate biodiversity. Although multiple hypotheses have been proposed, no consensus has been reached about the mechanism inducing this extinction event. In this study, I/Ca ratio of carbonate was used to unravel the changes in local oxygen content of the upper water column during this critical interval. The Devonian‐Carboniferous boundary was recorded in two shallow water carbonate sections in South China. [...]."

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Source: Science
Authors: Lewis J. Alcott et al.
DOI: 10.1126/science.aax6459

Abstract

"Oxygenation of Earth’s atmosphere and oceans occurred across three major steps during the Paleoproterozoic, Neoproterozoic, and Paleozoic eras, with each increase having profound consequences for the biosphere. Biological or tectonic revolutions have been proposed to explain each of these stepwise increases in oxygen, but the principal driver of each event remains unclear. Here we show, using a theoretical model, that the observed oxygenation steps are a simple consequence of internal feedbacks in the long-term biogeochemical cycles of carbon, oxygen, and phosphorus, and that there is no requirement for a specific stepwise external forcing to explain the course of Earth surface oxygenation. [...]."

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

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). [...]."

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Source: Wiley Online Library
Authors: Sabine K. Lengger et al.
DOI: 10.1029/2019GB006282

Abstract

"In response to rising CO₂ concentrations and increasing global sea surface temperatures, oxygen minimum zones (OMZ), or “dead zones”, are expected to expand. OMZs are fueled by high primary productivity, resulting in enhanced biological oxygen demand at depth, subsequent oxygen depletion, and attenuation of remineralization. This results in the deposition of organic carbon‐rich sediments. Carbon drawdown is estimated by biogeochemical models; however, a major process is ignored: carbon fixation in the mid‐ and lower water column. [...]."

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Source: The Independent
Author: Andy Gregory

""Dead zones” are rapidly appearing in the world’s oceans as they lose oxygen at an unprecedented rate due to climate change, sewage pollution and farming practices, presenting an existential threat to marine life and ecosystems, according to a vast new study. The overall level of oxygen in the oceans has dropped by roughly 2 per cent, while the number of known hypoxic “dead zones” – where oxygen levels are dangerously low – has skyrocketed from 45 known sites in the 1960s to at least 700 areas now dangerously devoid of the life-giving compound, some encompassing thousands of square miles. [...]."

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Source: The New York Times

"The world’s oceans are gasping for breath, a report issued Saturday at the annual global climate talks in Madrid has concluded. The report represents the combined efforts of 67 scientists from 17 countries and was released by the International Union for Conservation of Nature. It found that oxygen levels in the world’s oceans declined by roughly 2 percent between 1960 and 2010. The decline, called deoxygenation, is largely attributed to climate change, although other human activities are contributing to the problem. One example is so-called nutrient runoff, when too many nutrients from fertilizers used on farms and lawns wash into waterways. [...]."

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Source: IUCN
Authors: D. Laffoley & J. M. Baxter
DOI: 10.2305/IUCN.CH.2019.13.en

Abstract

"The ocean represents 97% of the physical habitable space on the planet and is central to sustaining all life on Earth. Since 2000 significant and dedicated effort has been directed at raising awareness and understanding of the consequences of greenhouse gas emissions on the ocean. Carbon dioxide emitted by human activities is driving the ocean towards more acidic conditions. Only in the past decade has it started to become more widely recognized that the temperature of the global ocean is also being significantly affected as a result of the effect that the carbon dioxide and other potent greenhouse gases are having in the Earth’s atmosphere. [...]."

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Source: Nature 
Authors: Emma L. Cross et al.
DOI: 10.1038/s41598-019-53930-8

Abstract

"Coastal ecosystems experience substantial natural fluctuations in pCO₂ and dissolved oxygen (DO) conditions on diel, tidal, seasonal and interannual timescales. Rising carbon dioxide emissions and anthropogenic nutrient input are expected to increase these pCO₂ and DO cycles in severity and duration of acidification and hypoxia. [...]."

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Source: Sasakawa Peace Foundation
Author: Ayako Yutsudo

"Ocean warming, acidification, deoxygenation, and marine heatwaves are all pressing marine issues that are quietly intensifying around the world. These challenges are diverse and occur on a massive scale, making it difficult for people to understand the full extent of the problem. To shed some light on this topic, the Sasakawa Peace Foundation (SPF) spoke with Mr. Tsunoda, Senior Research Fellow at the Ocean Policy Research Institute (OPRI). [...]."

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Source: New Atlas
Author: David Szondy

"An international team of researchers led by the University of Exeter suggests that a wide variety of marine species could be used for monitoring the world's oceans. Using electronic tags, scientists could exploit the natural behavior of sharks, penguins, turtles, seals and other species to fill gaps in our knowledge of the seas. With three-quarters of the Earth's surface covered with water, having a comprehensive understanding of the oceans is very important in dealing with everything from fishing quotas to climate change. The problem is that the oceans are much bigger than most people realize and many parts aren't easily, if at all, accessible. [...]."

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Source: The Washington Post

"TOMBWA, Angola — His ancestors were Portuguese colonialists who settled on this otherworldly stretch of coast, wedged between a vast desert and the southern Atlantic. They came looking for the one thing this barren region had in abundance: fish. By the time Mario Carceija Santos was getting into the fishing business half a century later, in the 1990s, Angola had won independence and the town of Tombwa was thriving. There were 20 fish factories strung along the bay, a constellation of churches and schools, a cinema hall built in art deco, and, in the central plaza, massive drying racks for the tons upon tons of fish hauled out of the sea. [...]."

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Source: Nature 
Authors: Catalina Aguirre et al.
DOI: 10.1038/s41612-019-0101-9

Abstract

"The climate of the ocean’s eastern boundaries is strongly influenced by subtropical anticyclones, which drive a surface wind stress that promotes coastal upwelling of nutrient-rich subsurface water that supports high primary productivity and an abundance of food resources. Understanding the projected response of upwelling-favourable winds to climate change has broad implications for coastal biogeochemistry, ecology, and fisheries. [...]."

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Source: Nature 
Authors: Rosie J. Chance et al.
DOI: 10.1038/s41597-019-0288-y

Abstract

"The marine iodine cycle has significant impacts on air quality and atmospheric chemistry. Specifically, the reaction of iodide with ozone in the top few micrometres of the surface ocean is an important sink for tropospheric ozone (a pollutant gas) and the dominant source of reactive iodine to the atmosphere. Sea surface iodide parameterisations are now being implemented in air quality models, but these are currently a major source of uncertainty. [...]."

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Source: University of Bristol

"New research led by scientists at the University of Bristol has shown that the feedback mechanisms that were thought to keep the marine nitrogen cycle relatively stable over geological time can break down when oxygen levels in the ocean decline significantly. The nitrogen cycle is essential to all forms of life on Earth - nitrogen is a basic building block of DNA.The marine nitrogen cycle is strongly controlled by biology and small changes in the marine nitrogen cycle have major implications on life. [...]."

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Source: PNAS
Authors: B. David A. Naafs et al.
DOI: 10.1073/pnas.1905553116

Abstract

"The present-day marine nitrogen (N) cycle is strongly regulated by biology. Deficiencies in the availability of fixed and readily bioavailable nitrogen relative to phosphate (P) in the surface ocean are largely corrected by the activity of diazotrophs. This feedback system, termed the “nitrostat,” is thought to have provided close regulation of fixed-N speciation and inventory relative to P since the Proterozoic. [...]."

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Source: Wiley Online Library
Authors: Wenfei Ni et al. 
DOI: 10.1029/2019JC015274

Abstract

"Climate change is known to cause deoxygenation in the open ocean, but its effects on eutrophic and seasonally hypoxic estuaries and coastal oceans are less clear. Using Chesapeake Bay as a study site, we conducted climate downscaling projections for dissolved oxygen and found that the hypoxic and anoxic volumes would increase by 10‐30% between the late 20^th and mid‐21^st century. [...]."

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Source: Phys.org

"An annual model-based report on "dead-zone" conditions in the Chesapeake Bay during 2019 indicates the total volume of low-oxygen, "hypoxic" water was on the high end of the normal range for 1985 to 2018, a finding that scientists consider relatively good news. Dr. Marjy Friedrichs, a Virginia Institute of Marine Science professor and report card co-author, says "Even with environmental conditions that favor severe hypoxia, including record-high river input and light winds, our analysis shows that the total amount of hypoxia this year was within the normal range seen over the past 35 years." [...]."

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Source: Science Daily

"In an effort to reverse the decline in the health of the world's oceans, the United Nations (UN) has declared 2021 to 2030 to be the Decade of Ocean Science for Sustainable Development. One key requirement for the scientific initiative is data on existing global ocean conditions. An important trove of data is already available thanks to the Tara Oceans expedition, an international, interdisciplinary enterprise that collected 35,000 samples from all the world's oceans between 2009 and 2013. The samples were collected by researchers aboard one schooner, the Tara, at depths ranging from the surface to 1,000 meters deep. [...]."

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Source: Springer Link
Authors: Yutaka W. Watanabe et al.
DOI: 10.1007/s10872-019-00532-7

Abstract

"We constructed parameterizations for the estimation of dissolved inorganic carbon (DIC) and pH in the western North Pacific, including Japanese coastal regions. Parameterizations, determined as a function of potential temperature (θ) and dissolved oxygen (DO), provided strong correlations with direct measurements for DIC [the coefficient of determination (R²) = 0.99; the root mean square error (RMSE) = 8.49 µmol kg⁻¹] and pH (R² = 0.98, RMSE = 0.030). [...]."

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Source: Nature 
Authors: Florian Breider et al.
DOI: 10.1038/s41558-019-0605-7

Abstract

"Ocean acidification, induced by the increase in anthropogenic CO₂ emissions, has a profound impact on marine organisms and biogeochemical processes. The response of marine microbial activities to ocean acidification might play a crucial role in the future evolution of air–sea fluxes of biogenic gases such as nitrous oxide (N₂O), a strong GHG and the dominant stratospheric ozone-depleting substance. Here, we examine the response of N₂O production from nitrification to acidification in a series of incubation experiments conducted in subtropical and subarctic western North Pacific. [...]."

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Source: Earth System Dynamics
Authors: Fabian Reith et al.
DOI: 10.5194/esd-10-711-2019

Abstract

"We investigate the climate mitigation potential and collateral effects of direct injections of captured CO₂ into the deep ocean as a possible means to close the gap between an intermediate CO₂ emissions scenario and a specific temperature target, such as the 1.5 ^∘C target aimed for by the Paris Agreement. For that purpose, a suite of approaches for controlling the amount of direct CO₂ injections at 3000 m water depth are implemented in an Earth system model of intermediate complexity. [...]."

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Source: Biogeosciences
Authors: Insa Rapp et al.
DOI: 10.5194/bg-16-4157-2019

Abstract

"The availability of the micronutrient iron (Fe) in surface waters determines primary production, N₂ fixation, and microbial community structure in large parts of the world's ocean, and thus it plays an important role in ocean carbon and nitrogen cycles. Eastern boundary upwelling systems and the connected oxygen minimum zones (OMZs) are typically associated with elevated concentrations of redox-sensitive trace metals (e.g., Fe, manganese (Mn), and cobalt (Co)), with shelf sediments typically forming a key source. [...]."

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Source: Nature 
Authors: Jesse Wilson et al.
DOI: 10.1038/s41598-019-52430-z

Abstract

"Dissolved oxygen (DO) concentrations shape the biogeochemistry and ecological structure of aquatic ecosystems; as a result, understanding how and why DO varies in space and time is of fundamental importance. Using high-resolution, in situ DO time-series collected over the course of a year in a novel marine ecosystem (Jellyfish Lake, Palau), we show that DO declined throughout the marine lake and subsequently recovered in the upper water column. [...]."

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Source: Frontiers in Marine Science
Authors: Grace K. Saba et al.
DOI: 10.3389/fmars.2019.00664

Abstract

"Coastal and ocean acidification can alter ocean biogeochemistry, with ecological consequences that may result in economic and cultural losses. Yet few time series and high resolution spatial and temporal measurements exist to track the existence and movement of water low in pH and/or carbonate saturation. Past acidification monitoring efforts have either low spatial resolution (mooring) or high cost and low temporal and spatial resolution (research cruises). [...]."

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Source: Nature 
Authors: Susana Flecha et al.
DOI: 10.1038/s41598-019-52084-x

Abstract

"Seawater pH is undergoing a decreasing trend due to the absorption of atmospheric CO₂, a phenomenon known as ocean acidification (OA). Biogeochemical processes occurring naturally in the ocean also change pH and hence, for an accurate assessment of OA, the contribution of the natural component to the total pH variation must be quantified. [...]."

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Source: Frontiers in Marine Science
Authors: Akash R. Sastri et al.
DOI: 10.3389/fmars.2019.00653

Abstract

"As ocean acidification (OA) sensor technology develops and improves, in situ deployment of such sensors is becoming more widespread. However, the scientific value of these data depends on the development and application of best practices for calibration, validation, and quality assurance as well as on further development and optimization of the measurement technologies themselves. Here, we summarize the results of a 2-day workshop on OA sensor best practices held in February 2018, in Victoria, British Columbia, Canada, drawing on the collective experience and perspectives of the participants. [...]."

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Source: Science Direct
Authors: Matthieu Le Hénaff et al.
DOI: 10.1016/j.csr.2019.103988

Abstract

"Remotely sensed and in situ data, in tandem with numerical modeling, are used to explore the causes of an episode of localized but severe mortality of corals, sponges, and other invertebrates at the Flower Garden Banks (FGB) National Marine Sanctuary in July 2016. [...]."

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Source: Wiley Online Library
Authors: Shannon G. Klein et al.
DOI: 10.1111/gcb.14879

Abstract

"Research efforts have intensified to foresee the prospects for marine biomes under climate change and anthropogenic drivers over varying temporal and spatial scales. Parallel with these efforts is the utilization of terminology, such as ‘ocean acidification’ and ‘ocean deoxygenation’, that can foster rapid comprehension of complex processes driving carbon dioxide (CO₂) and oxygen (O₂) concentrations in the global ocean and thus, are now widely used in discussions within and beyond academia. [...]."

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Source: Biogeosciences
Authors: Eric J. Morgan et al.
DOI: 10.5194/bg-16-4065-2019

Abstract

"Ground-based atmospheric observations of CO₂, δ(O₂∕N₂), N₂O, and CH₄ were used to make estimates of the air–sea fluxes of these species from the Lüderitz and Walvis Bay upwelling cells in the northern Benguela region, during upwelling events. Average flux densities (±1σ) were 0.65±0.4 µmol m⁻² s⁻¹ for CO₂, −5.1±2.5 µmol m⁻² s⁻¹ for O₂ (as APO), 0.61±0.5 nmol m⁻² s⁻¹ for N₂O, and 4.8±6.3 nmol m⁻² s⁻¹ for CH₄. A comparison of our top-down (i.e., inferred from atmospheric anomalies) flux estimates with shipboard-based measurements showed that the two approaches agreed within ±55 % on average, though the degree of agreement varied by species and was best for CO₂. [...]."

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Source: Ocean Science
Authors: Ivica Vilibić et al.
DOI: 10.5194/os-15-1351-2019

Abstract

"The paper documents seasonality, interannual-to-decadal variability, and trends in temperature, salinity, and density over a transect in the shallow northern Adriatic Sea (Mediterranean Sea) between 1979 and 2017. The amplitude of seasonality decreases with depth and is much larger in temperature and density than in salinity. [...]."

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Source: Wiley Online Library
Authors: Matias Pizarro‐Koch et al.
DOI: 10.1029/2019JC015201

Abstract

"We investigate the seasonal variability of the southern tip (30°–38°S) of the eastern South Pacific oxygen minimum zone (OMZ) based on a high horizontal resolution (1/12°) regional coupled physical‐biogeochemical model simulation. The simulation is validated by available in situ observations and the OMZ seasonal variability is documented. The model OMZ, bounded by the contour of 45 μM, occupies a large volume (4.5x10⁴ km³) during the beginning of austral winter and a minimum (3.5x10⁴ km³) at the end of spring, just 1 and 2 months after the southward transport of the Peru‐Chile Undercurrent (PCUC) is maximum and minimum, respectively. [...]."

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Source: Nature 
Authors: Emily J. Zakem et al.
DOI: 10.1038/s41396-019-0523-8

Abstract

"Mechanistic description of the transition from aerobic to anaerobic metabolism is necessary for diagnostic and predictive modeling of fixed nitrogen loss in anoxic marine zones (AMZs). In a metabolic model where diverse oxygen- and nitrogen-cycling microbial metabolisms are described by underlying redox chemical reactions, we predict a transition from strictly aerobic to predominantly anaerobic regimes as the outcome of ecological interactions along an oxygen gradient, obviating the need for prescribed critical oxygen concentrations. [...]."

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Source: University of Rochester
Author: Lindsey Valich

"Methane is a potent greenhouse gas that is being added to the atmosphere through both natural processes and human activities, such as energy production and agriculture. To predict the impacts of human emissions, researchers need a complete picture of the atmosphere’s methane cycle. They need to know the size of the inputs—both natural and human—as well as the outputs. They also need to know how long methane resides in the atmosphere. [...]."

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Source: Nature 
Authors: Balsam Al-Janabi et al.
DOI: 10.1038/s41598-019-51099-8

Abstract

"Ecological impact of global change is generated by multiple synchronous or asynchronous drivers which interact with each other and with intraspecific variability of sensitivities. In three near-natural experiments, we explored response correlations of full-sibling germling families of the seaweed Fucus vesiculosus towards four global change drivers: elevated CO₂ (ocean acidification, OA), ocean warming (OW), combined OA and warming (OAW), nutrient enrichment and hypoxic upwelling. [...]."

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Source: Nature 
Authors: Pearse J. Buchanan et al.
DOI: 10.1038/s41467-019-12549-z

Abstract

"Roughly a third (~30 ppm) of the carbon dioxide (CO₂) that entered the ocean during ice ages is attributed to biological mechanisms. A leading hypothesis for the biological drawdown of CO₂ is iron (Fe) fertilisation of the high latitudes, but modelling efforts attribute at most 10 ppm to this mechanism, leaving ~20 ppm unexplained. [...]."

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Source: Phys.org

"Methane is a potent greenhouse gas that is being added to the atmosphere through both natural processes and human activities, such as energy production and agriculture. To predict the impacts of human emissions, researchers need a complete picture of the atmosphere's methane cycle. They need to know the size of the inputs—both natural and human—as well as the outputs. They also need to know how long methane resides in the atmosphere. [...]."

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Source: Nature 
Authors: Thomas Weber et al.  
DOI: 10.1038/s41467-019-12541-7

Abstract

"Oceanic emissions represent a highly uncertain term in the natural atmospheric methane (CH₄) budget, due to the sparse sampling of dissolved CH₄ in the marine environment. Here we overcome this limitation by training machine-learning models to map the surface distribution of methane disequilibrium (∆CH₄). Our approach yields a global diffusive CH₄ flux of 2–6TgCH₄yr⁻¹ from the ocean to the atmosphere, after propagating uncertainties in ∆CH₄ and gas transfer velocity. [...]."

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Source: Cordis

"ATLAS is one of these projects you can’t do justice to in a single-page article. For over 3.5 years now, a consortium of multinational industries, SMEs, governments and academia have been sailing across the Atlantic to assess its deep-sea ecosystems. In doing so, they’ve already managed to deeply enhance our understanding of the consequences of climate change as well as inform the development of better management policies and practices. [...]."

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Source: PNAS
Authors: Tais W. Dahl et al.
DOI: 10.1073/pnas.1901178116

Abstract

"The proliferation of large, motile animals 540 to 520 Ma has been linked to both rising and declining O₂ levels on Earth. To explore this conundrum, we reconstruct the global extent of seafloor oxygenation at approximately submillion-year resolution based on uranium isotope compositions of 187 marine carbonates samples from China, Siberia, and Morocco, and simulate O₂ levels in the atmosphere and surface oceans using a mass balance model constrained by carbon, sulfur, and strontium isotopes in the same sedimentary successions. [...]."

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Source: Oceanography
Authors: Francis Chan et al.
DOI: 10.5670/oceanog.2019.312

Abstract

"Coastal upwelling ecosystems around the world are defined by wind-generated currents that bring deep, nutrient-rich waters to the surface ocean where they fuel exceptionally productive food webs. These ecosystems are also now understood to share a common vulnerability to ocean acidification and hypoxia (OAH). In the California Current Large Marine Ecosystem (CCLME), reports of marine life die-offs by fishers and resource managers triggered research that led to an understanding of the risks posed by hypoxia. Similarly, unprecedented losses from shellfish hatcheries led to novel insights into the coastal expression of ocean acidification. [...]."

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Source: Frontiers in Marine Science
Authors: Konstantin Choumiline et al.
DOI: 10.3389/feart.2019.00237

Abstract

"Diverse studies predict global expansion of Oxygen Minimum Zones (OMZs) as a consequence of anthropogenic global warming. While the observed dissolved oxygen concentrations in many coastal regions are slowly decreasing, sediment core paleorecords often show contradictory trends. This is the case for numerous high-resolution reconstructions of oxygenation in the Eastern Tropical North Pacific (ETNP). [...]."

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Source: Phys.org
Author: Jessica Walker

"The importance of the ocean in climate regulation is enormous—yet undervalued. The ocean is estimated to have absorbed 93 percent of the excess heat generated by human activities since the 1970s, acting as a buffer against the global warming we've seen to date. The majority of the global carbon cycle circulates through the ocean, through marine food-webs and other processes, and carbon is locked-away in coastal and marine habitats and deep in ocean sediments. Coastal ecosystems alone sequester more carbon than terrestrial forest per unit area. [...]."

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Source: Nature
Authors: Janis Searles Jones
DOI: 10.1038/d41586-019-02832-w

"More than two-thirds of the planet is covered by ocean, but these waters have not received their due in terms of research dollars or public attention. That means the dangers that the seas face from climate change — and the solutions that they offer — are often overlooked. [...]."

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Source: Science Direct
Authors: C. Mettam et al.
DOI: 10.1016/j.epsl.2019.115800

Abstract

"A persistently aerobic marine nitrogen cycle featuring the biologically mediated oxidation of ammonium to nitrate has likely been in place since the Great Oxidation Event (GOE) some 2.3 billion years ago. Although nitrogen isotope data from some Neoarchaean sediments suggests transient nitrate availability prior to the GOE, these data are open to other interpretations. [...]."

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Source: Wiley Online Library
Authors: Stilianos Louca et al.
DOI: 10.1111/gbi.12357

Abstract

"Permanently anoxic regions in the ocean are widespread and exhibit unique microbial metabolic activity exerting substantial influence on global elemental cycles and climate. Reconstructing microbial metabolic activity rates in these regions has been challenging, due to the technical difficulty of direct rate measurements. In Cariaco Basin, which is the largest permanently anoxic marine basin and an important model system for geobiology, long‐term monitoring has yielded time series for the concentrations of biologically important compounds; however, the underlying metabolite fluxes remain poorly quantified. [...]."

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Source: Frontiers in Marine Science
Authors: Tobias Steinhoff et al.
DOI: 10.3389/fmars.2019.00544

Abstract

"The European Research Infrastructure Consortium “Integrated Carbon Observation System” (ICOS) aims at delivering high quality greenhouse gas (GHG) observations and derived data products (e.g., regional GHG-flux maps) for constraining the GHG balance on a European level, on a sustained long-term basis. The marine domain (ICOS-Oceans) currently consists of 11 Ship of Opportunity lines (SOOP – Ship of Opportunity Program) and 10 Fixed Ocean Stations (FOSs) spread across European waters, including the North Atlantic and Arctic Oceans and the Barents, North, Baltic, and Mediterranean Seas. [...]."

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Source: Nature
Authors: S. Comeau et al.
DOI: 10.1038/s41598-019-49044-w

Abstract

"Natural variability in pH in the diffusive boundary layer (DBL), the discrete layer of seawater between bulk seawater and the outer surface of organisms, could be an important factor determining the response of corals and coralline algae to ocean acidification (OA). Here, two corals with different morphologies and one coralline alga were maintained under two different regimes of flow velocities, pH, and light intensities in a 12 flumes experimental system for a period of 27 weeks. [...]."

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Source: PLOS
Authors: Louise Cominassi et al.
DOI: 10.1371/journal.pone.0221283

Abstract

"Ocean acidification and ocean warming (OAW) are simultaneously occurring and could pose ecological challenges to marine life, particularly early life stages of fish that, although they are internal calcifiers, may have poorly developed acid-base regulation. This study assessed the effect of projected OAW on key fitness traits (growth, development and swimming ability) in European sea bass (Dicentrarchus labrax) larvae and juveniles. [...]."

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Source: Wiley Online Library
Authors: C.R. Selden et al.
DOI: 10.1029/2019GB006242

Abstract

"The Eastern Tropical North Pacific (ETNP) Ocean hosts one of the world's largest oceanic oxygen deficient zones (ODZs). Hotspots for reactive nitrogen (N_r) removal processes, ODZs generate conditions proposed to promote N_r inputs via dinitrogen (N₂) fixation. In this study, we quantified N₂ fixation rates by ¹⁵N‐tracer bioassay across oxygen, nutrient and light gradients within and adjacent to the ODZ. [...]."

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Source: Chinese Academy of Sciences

"Chinese scientists have developed an online system to monitor marine-biochemical elements, according to Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, who led the project. The research team developed the online monitoring instruments by integrating three measurement modules namely, the chlorophyll module, productivity module and dissolved oxygen module, which are all developed by the team itself. [...]."

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Source: Earth System Dynamics
Authors: Tronje P. Kemena et al.
DOI: 10.5194/esd-10-539-2019

Abstract

"Previous studies have suggested that enhanced weathering and benthic phosphorus (P) fluxes, triggered by climate warming, can increase the oceanic P inventory on millennial timescales, promoting ocean productivity and deoxygenation. In this study, we assessed the major uncertainties in projected P inventories and their imprint on ocean deoxygenation using an Earth system model of intermediate complexity for the same business-as-usual carbon dioxide (CO₂) emission scenario until the year 2300 and subsequent linear decline to zero emissions until the year 3000. [...]."

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Source: Science
Authors: Folco Giomi et al.
DOI:  10.1126/sciadv.aax1814

Abstract

"Ocean warming affects the life history and fitness of marine organisms by, among others, increasing animal metabolism and reducing oxygen availability. In coastal habitats, animals live in close association with photosynthetic organisms whose oxygen supply supports metabolic demands and may compensate for acute warming. [...]."

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Source: GeoScienceWorld
Authors: Chelsie N. Bowman et al.
DOI: 10.1130/G46571.1

Abstract

"The late Ludlow Lau Event was a severe biotic crisis in the Silurian, characterized by resurgent microbial facies and faunal turnover rates otherwise only documented during the "big five" mass extinctions. This asynchronous late Silurian marine extinction event preceded an associated positive carbon isotope excursion (CIE), the Lau CIE, although a mechanism for this temporal offset remains poorly constrained. [...]."

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Source: Science Daily

"For years, scientists struggled to connect a mechanism to this mass extinction, one of the 10 most dramatic ever recorded in Earth's history. Now, researchers have confirmed that this event, referred to by scientists as the Lau/Kozlowskii extinction, was triggered by an all-too-familiar culprit: rapid and widespread depletion of oxygen in the global oceans. [...]."

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Source: Biogeosciences
Authors: Elina A. Virtanen et al.
DOI: 10.5194/bg-16-3183-2019

Abstract

"Hypoxia is an increasing problem in marine ecosystems around the world. While major advances have been made in our understanding of the drivers of hypoxia, challenges remain in describing oxygen dynamics in coastal regions. The complexity of many coastal areas and lack of detailed in situ data have hindered the development of models describing oxygen dynamics at a sufficient spatial resolution for efficient management actions to take place. [...]."

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Source: Oxford University Press
Authors: Lina Russ et al. 
DOI: 10.1093/femsec/fiz137

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). [...]."

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Source: Safety4Sea

"The last two years MV Columbia records the ocean’s vitals every three minutes, along a 1,600-kilometer route through the Inside Passage. This includes the coastal region from Puget Sound to the Alaska Panhandle. The ship measures the sea's temperature, salinity, dissolved oxygen content, and carbon dioxide concentration, aiming to monitor ocean acidification. [...]."

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Source: Frontiers in Marine Science
Authors: Pablo N. Trucco-Pignata et al.
DOI: 10.3389/fmars.2019.00459

Abstract

"As a result of anthropogenic activities, it has been predicted that the ocean will be challenged with rising temperature, increased stratification, ocean acidification, stronger more frequent tropical storms, and oxygen depletion. In the tropical Pacific off central Mexico all these phenomena are already occurring naturally, providing a laboratory from which to explore ocean biogeochemical dynamics that are predicted under future anthropogenic forcing conditions. [...]."

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Source: Wiley Online Library
Authors: Fabian Große et al.
DOI: 10.1029/2019JC015230

Abstract

"The Mississippi and Atchafalaya River System discharges large amounts of freshwater and nutrients into the northern Gulf of Mexico (NGoM). These lead to increased stratification and elevate primary production in the outflow region. Consequently, hypoxia (oxygen <62.5 mmol/m³), extending over an area of roughly 15,000 km², forms every summer in bottom waters. [...]."

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Source: MDPI 
Authors: Vanessa Hull et al.
DOI: 10.3390/su11164450

Abstract

"The world’s oceans face unprecedented anthropogenic threats in the globalized era that originate from all over the world, including climate change, global trade and transportation, and pollution. Marine protected areas (MPAs) serve important roles in conservation of marine biodiversity and ecosystem resilience, but their success is increasingly challenged in the face of such large-scale threats. [...]."

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Source: Biogeosciences
Author: Daniela Niemeyer et al.
DOI: 10.5194/bg-16-3095-2019

Abstract

"Particle aggregation determines the particle flux length scale and affects the marine oxygen concentration and thus the volume of oxygen minimum zones (OMZs) that are of special relevance for ocean nutrient cycles and marine ecosystems and that have been found to expand faster than can be explained by current state-of-the-art models. [...]."

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Source: Ocean Science
Authors: Sinikka T. Lennartz et al.
DOI: 10.5194/os-15-1071-2019

Abstract

"Oceanic emissions of the climate-relevant trace gases carbonyl sulfide (OCS) and carbon disulfide (CS₂) are a major source to their atmospheric budget. Their current and future emission estimates are still uncertain due to incomplete process understanding and therefore inexact quantification across different biogeochemical regimes. [...]."

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Source: Phys.org

"What will the ecology of the Salish Sea look like in the year 2095? It's an important question for millions of people who live along and near the shores of this intricate, interconnected network of coastal waterways, inlets, bays, and estuaries that encompasses Puget Sound in Washington state and the deep waters of southwest British Columbia. A research team from PNNL found that the inner Salish Sea is resilient, and that future response to climate change—while significant—will be less severe than the open ocean. [...]."

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Source: Ocean Science
Authors: Pär Jansson et al. 
DOI: 10.5194/os-15-1055-2019

Abstract

"Methane (CH4) in marine sediments has the potential to contribute to changes in the ocean and climate system. Physical and biochemical processes that are difficult to quantify with current standard methods such as acoustic surveys and discrete sampling govern the distribution of dissolved CH4 in oceans and lakes. [...]."

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Source: Nature 
Authors: Tais W. Dahl et al.
DOI: 10.1038/s41598-019-48123-2

Abstract

"Oxygen is a prerequisite for all large and motile animals. It is a puzzling paradox that fossils of benthic animals are often found in black shales with geochemical evidence for deposition in marine environments with anoxic and sulfidic bottom waters. It is debated whether the geochemical proxies are unreliable, affected by diagenesis, or whether the fossils are transported from afar or perhaps were not benthic. [...]."

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Source: Frontiers in Marine Science
Authors: Robert E. Todd et al.
DOI: 10.3389/fmars.2019.00423

Abstract

"Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. The next steps in the development of boundary current observing systems are considered, leading to several specific recommendations. [...]."

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Source: Nature 
Authors: Steven D’Hondt et al.
DOI: 10.1038/s41467-019-11450-z

Abstract

"Subseafloor microbial activities are central to Earth’s biogeochemical cycles. They control Earth’s surface oxidation and major aspects of ocean chemistry. They affect climate on long timescales and play major roles in forming and destroying economic resources. In this review, we evaluate present understanding of subseafloor microbes and their activities, identify research gaps, and recommend approaches to filling those gaps. [...]."

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Source: Science Daily

"Ocean acidification is bad news for shellfish, as it makes it harder for them to form their calcium-based shells. But climate change could also have multiple other impacts that make California bays less hospitable to shelled organisms like oysters, which are a key part of the food web. Changes to water temperature and chemistry resulting from human-caused climate change could shrink the prime habitat and farming locations for oysters in California bays, according to a new study from the University of California, Davis. [...]."

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Source: Phys.org
Author: Felicia Chou

"NASA has selected a space-based instrument under its Earth Venture Instrument (EVI) portfolio that will make observations of coastal waters to help protect ecosystem sustainability, improve resource management, and enhance economic activity. The selected Geosynchronous Littoral Imaging and Monitoring Radiometer (GLIMR) instrument, led by principal investigator Joseph Salisbury at the University of New Hampshire, Durham, will provide unique observations of ocean biology, chemistry, and ecology in the Gulf of Mexico, portions of the southeastern United States coastline, and the Amazon River plume—where the waters of the Amazon River enter the Atlantic Ocean. [...]."

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Source: Frontiers in Marine Science
Authors: Dean Roemmich et al.
DOI: 10.3389/fmars.2019.00439

Abstract

"The Argo Program has been implemented and sustained for almost two decades, as a global array of about 4000 profiling floats. Argo provides continuous observations of ocean temperature and salinity versus pressure, from the sea surface to 2000 dbar. The successful installation of the Argo array and its innovative data management system arose opportunistically from the combination of great scientific need and technological innovation. Through the data system, Argo provides fundamental physical observations with broad societally-valuable applications, built on the cost-efficient and robust technologies of autonomous profiling floats. [...]."

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Source: NOAA

"This year’s Gulf of Mexico “dead zone”— an area of low oxygen that can kill fish and marine life — is approximately 6,952 square miles, according to NOAA-supported scientists. The measured size of the dead zone, also called the hypoxic zone, is the 8th largest in the 33-year record and exceeds the 5,770-square-mile average from the past five years. [...]."

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Source: Trends in Ecology & Evolution
Authors: Christopher L. Lawson et al.
DOI: 10.1016/j.tree.2019.07.001

Abstract

"Energetics studies have illuminated how animals partition energy among essential life processes and survive in extreme environments or with unusual lifestyles. There are few bioenergetics measurements for elasmobranch megafauna; the heaviest elasmobranch for which metabolic rate has been measured is only 47.7 kg, despite many weighing >1000 kg. Bioenergetics models of elasmobranch megafauna would answer fundamental ecological questions surrounding this important and vulnerable group, and enable an understanding of how they may respond to changing environmental conditions, such as ocean warming and deoxygenation. [...]."

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Source: Springer Link
Authors: Anna Pagnone et al.
DOI: 10.1007/s10236-019-01288-w

Abstract

"Trace metal measurements in recent years have revealed a complex distribution of dissolved iron (dFe) in the ocean that models still struggle to reproduce. The GEOTRACES section GA03 across the subtropical North Atlantic was chosen to study the driving processes involved in the Fe cycle in the region. [...]."

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Source: Wiley Online Library
Authors: Emily D. Matys et al.
DOI: 10.1111/gbi.12353

Abstract

"Bacteriohopanepolyols (BHPs) are pentacyclic triterpenoid lipids that contribute to the structural integrity and physiology of some bacteria. Because some BHPs originate from specific classes of bacteria, BHPs have potential as taxonomically and environmentally diagnostic biomarkers. For example, a stereoisomer of bacteriohopanetetrol (informally BHT II) has been associated with anaerobic ammonium oxidation (anammox) bacteria and suboxic to anoxic marine environments where anammox is active. [...]."

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Source: Frontiers in Earth Science
Authors: Nicolaas Glock et al.
DOI: 10.3389/feart.2019.00175

Abstract

"Oceanic oxygen decline due to anthropogenic climate change is a matter of growing concern. A quantitative oxygen proxy is highly desirable in order to identify and monitor recent dynamics as well as to reconstruct pre-Anthropocene changes in amplitude and extension of oxygen depletion. Geochemical proxies like foraminiferal I/Ca ratios seem to be promising redox proxies. [...]."

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Source: Science Direct
Authors: S. Bruggmann et al.
DOI: 10.1016/j.gca.2019.05.001

Abstract

"Chromium (Cr) isotope fractionation is sensitive to redox changes and the Cr isotopic composition (δ⁵³Cr) of sedimentary rocks has been used to reconstruct marine redox conditions and atmospheric oxygenation in the past. However, little is known about the behaviour of chromium isotopes across modern marine redox boundaries. We investigated Cr concentrations and δ⁵³Cr variations in seawater and sediment across the Peruvian oxygen minimum zone (OMZ) to provide a better understanding of Cr cycling in the ocean. [...]."

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Source: Science Direct
Authors: S. K. Gangl et al.
DOI: 10.1016/j.epsl.2019.04.028

Abstract

"Oceanic Anoxic Event 2 (OAE 2), which took place around the Cenomanian–Turonian boundary (∼94 Ma), is associated with extreme perturbations to the global carbon cycle, affected ocean basins worldwide and was associated with significant biological turnover. Although this event has been well studied in the northern hemisphere, the evolution and character of OAE 2, particularly in terms of the vertical and lateral extent of anoxia, is poorly constrained in the palaeo-Pacific Ocean. [...]."

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Source: EOS
Author: Mary Caperton Morton
DOI: 10.1029/2019EO128019

"In 2019, predictions indicate that the Gulf of Mexico will retain the dubious distinction of having the second-largest low-oxygen dead zone on Earth (the Baltic Sea remains firmly in first place). By the end of the summer, the hypoxic region on the seafloor at the mouth of the Mississippi River is expected to occupy over 22,000 square kilometers—an area the size of the state of Massachusetts. [...]."

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Source: Nature
Authors: Kazumi Ozaki et al.
DOI: 10.1038/s41467-019-10872-z

Abstract

"The emergence of oxygenic photosynthesis created a new niche with dramatic potential to transform energy flow through Earth’s biosphere. However, more primitive forms of photosynthesis that fix CO2 into biomass using electrons from reduced species like Fe(II) and H2 instead of water would have competed with Earth’s early oxygenic biosphere for essential nutrients. [...]."

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Source: Science Direct
Authors: Hermann W. Bange et al.
DOI: 10.1016/j.dsr2.2019.06.015

Abstract

"Nitrous oxide (N₂O) is a climate-relevant atmospheric trace gas. It is produced as an intermediate of the nitrogen cycle. The open and coastal oceans are major sources of atmospheric N₂O. However, its oceanic distribution is still largely unknown. Here we present the first measurements of the water column distribution of N₂O in the Gulf of Aqaba and the Red Sea. [...]."

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Source: Biogeosciences
Authors: Kristin Doering et al.
DOI: 10.5194/bg-16-2163-2019

Abstract

"The stable sedimentary nitrogen isotope compositions of bulk organic matter (δ¹⁵N_bulk) and the silicon isotope composition of diatoms (δ³⁰Si_BSi) both mainly reflect the degree of past nutrient utilization by primary producers. However, in ocean areas where anoxic and suboxic conditions prevail, the δ¹⁵N_bulk signal ultimately recorded within the sediments is also influenced by water column denitrification, causing an increase in the subsurface δ¹⁵N signature of dissolved nitrate (δ¹⁵NO⁻₃) upwelled to the surface. [...]."

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Source: Frontiers in Marine Science
Authors: Jessica N. Cross et al.
DOI: 10.3389/fmars.2019.00356

Abstract

"Ocean acidification (OA) describes the progressive decrease in the pH of seawater and other cascading chemical changes resulting from oceanic uptake of atmospheric carbon. These changes can have important implications for marine ecosystems, creating risk for commercial industries, subsistence communities, cultural practices, and recreation. [...]."

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Source: EurekAlert

"A team of natural and social scientists, supported by 25 post-secondary students from the U.S. and Canada, will study vital signs of a rapidly changing Arctic Ocean this summer, and offer the public a chance to share the experience in real time. The innovative, 18-day Northwest Passage Project research expedition will depart on July 18 from the U.S. Air Base in Thule, Greenland, aboard the Swedish Icebreaker Oden, returning to Thule August 4 after a 2,000 nautical mile voyage through the Northwest Passage [...]."

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Source: IEEE Xplore
Authors: Shufeng Li et al.
DOI: 10.1109/OCEANS.2018.8604623

Abstract

"Mesoscale eddies, as a considerable contributor to the transport of ocean heat, dissolved oxygen and other biochemical tracers, have an important influence on the distribution of marine resources and global climate change. The purpose of this research is to capture the high variability of an anticyclonic eddy in South China Sea to observe its thermohaline vertical structure in different transections. [...]."

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Source: Phys.org

"The oceans are losing oxygen. Numerous studies based on direct measurements in recent years have shown this. Since water can dissolve less gas as temperatures rise, these results were not surprising. In addition to global warming, factors such as eutrophication of the coastal seas also contribute to the ongoing deoxygenation. [...]."

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Source: Nature 
Authors: Andreas Oschlies et al.
DOI: 10.1038/s41467-019-10813-w

Abstract

"Oceanic anoxic events have been associated with warm climates in Earth history, and there are concerns that current ocean deoxygenation may eventually lead to anoxia. Here we show results of a multi-millennial global-warming simulation that reveal, after a transitory deoxygenation, a marine oxygen inventory 6% higher than preindustrial despite an average 3 °C ocean warming. [...]."

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Source: Springer Link
Authors: Liyang Yang et al.
DOI: 10.1007/s11356-019-05700-2

Abstract

"Dissolved organic matter (DOM) is a critical component in aquatic ecosystems, yet its seasonal variability and reactivity remain not well constrained. These were investigated at the land-ocean interface of a subtropical river (Minjiang River, SE China), using absorption and fluorescence spectroscopy. [...]."

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

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. [...]."

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Source: The Royal Society
Authors: John I. Spicer & Simon A. Morley
DOI: 10.1098/rstb.2019.0034

Abstract

"It has been suggested that giant Antarctic marine invertebrates will be particularly vulnerable to declining O2 levels as our ocean warms in line with current climate change predictions. Our study provides some support for this oxygen limitation hypothesis, with larger body sizes being generally more sensitive to O2 reductions than smaller body sizes. [...]."

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Source: Science Daily

"Researchers have presented support for the theory that marine invertebrates with larger body size are generally more sensitive to reductions in oxygen than smaller animals, and so will be more sensitive to future global climate change. However, evolutionary innovation can to some extent offset any respiratory disadvantages of large body size. [...]."

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Source: Nature 
Authors: Rui Zhao et al.
DOI: 10.1038/s41598-019-44585-6

Abstract

"More than half of the global ocean floor is draped by nutrient-starved sediments characterized by deep oxygen penetration and a prevalence of oxidized nitrogen. Despite low energy availability, this habitat hosts a vast microbial population, and geochemical characteristics suggest that nitrogen compounds are an energy source critical to sustaining this biomass. [...]."

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Source: Science Direct
Authors: Renato Salvatteci et al.
DOI: 10.1016/j.pocean.2019.05.006

Abstract

"Upwelling of cold, nutrient-rich water from the oxygen minimum zone (OMZ) off Peru sustains the world’s highest production of forage fish, mostly composed of anchovy (Engraulis ringens). However, the potential impacts of climate change on upwelling dynamics and thus fish productivity in the near future are uncertain. Here, we reconstruct past changes in fish populations during the last 25,000 years to unravel their response to changes in OMZ intensity and productivity. [...]."

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Source: Nature
Authors: Ethan C. Campbell et al.
DOI: 10.1038/s41586-019-1294-0

Abstract

"Offshore Antarctic polynyas—large openings in the winter sea ice cover—are thought to be maintained by a rapid ventilation of deep-ocean heat through convective mixing. These rare phenomena may alter abyssal properties and circulation, yet their formation mechanisms are not well understood. Here we demonstrate that concurrent upper-ocean preconditioning and meteorological perturbations are responsible for the appearance of polynyas in the Weddell Sea region of the Southern Ocean. [...]."

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Source: National Geographic
Author: Sarah Gibbens

"Just off the coast of Louisiana and Texas where the Mississippi River empties, the ocean is dying. The cyclical event known as the dead zone occurs every year, but scientists predict that this year's could be one of the largest in recorded history. Annual spring rains wash the nutrients used in fertilizers and sewage into the Mississippi. That fresh water, less dense than ocean water, sits on top of the ocean, preventing oxygen from mixing through the water column. Eventually those freshwater nutrients can spur a burst of algal growth, which consumes oxygen as the plants decompose. [...]."

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Source: NOAA

"NOAA scientists are forecasting this summer’s Gulf of Mexico hypoxic zone or ‘dead zone’ – an area of low to no oxygen that can kill fish and other marine life – to be approximately 7,829 square miles, or roughly the size of Massachusetts. The annual prediction is based on U.S. Geological Survey river flow and nutrient data. [...]."

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Source: France24

"Armed with better data than ever before, scientists have in recent months sounded the alarm over the rising pace of global warming and the parlous state of Nature. But there is another area of concern, one that covers two thirds of the planet and plays a crucial role in absorbing dangerous greenhouse gases and regulating everything from food chains to weather patterns. Oceans are crucial to life on Earth, yet they frequently only feature in the environment debate when plastic pollution or fish-stock declines are discussed. But experts believe that might be changing. “We have an important opportunity over the next 18 months to do something for oceans,” said Dan Laffoley, from the International Union for the Conservation of Nature. [...]."

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Source: Biogeosciences
Authors: Tim Fischer et al.
DOI: 10.5194/bg-16-2307-2019

Abstract

"The coastal upwelling regime off Peru in December 2012 showed considerable vertical concentration gradients of dissolved nitrous oxide (N₂O) across the top few meters of the ocean. The gradients were predominantly downward, i.e., concentrations decreased toward the surface. Ignoring these gradients causes a systematic error in regionally integrated gas exchange estimates, when using observed concentrations at several meters below the surface as input for bulk flux parameterizations – as is routinely practiced. [...]."

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Source: Oxford University Press
Authors: William Christopher Long et al.
DOI: 10.1093/icesjms/fsz090

Abstract

"Ocean acidification is a decrease in pH resulting from dissolution of anthropogenic CO₂ in the oceans that has physiological effects on many marine organisms. Juvenile red and blue king crabs (Paralithodes camtschaticus and P. platypus) exhibit both increased mortality and decreased growth in acidified waters. In this study, we determined how ocean acidification affects oxygen consumption, feeding rates, and growth in both species. [...]."

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Source: Frontiers in Marine Science
Authors: Jorge Cardich et al.
DOI: 10.3389/fmars.2019.00270

Abstract

"Subsurface water masses with permanent oxygen deficiency (oxygen minimum zones, OMZ) are typically associated with upwelling regions and exhibit a high sensitivity to climate variability. Over the last decade, several studies have reported a global ocean deoxygenation trend since 1960 and a consequent OMZ expansion. However, some proxy records suggest an oxygenation trend for the OMZ over the margins of the Tropical North East Pacific since ca. 1850. [...]."

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Source: Science Direct
Authors: Florian Scholz et al.
DOI: 10.1016/j.epsl.2019.04.008

Abstract

"Oceanic Anoxic Events (OAEs) in Earth's history are regarded as analogues for current and future ocean deoxygenation, potentially providing information on its pacing and internal dynamics. In order to predict the Earth system's response to changes in greenhouse gas concentrations and radiative forcing, a sound understanding of how biogeochemical cycling differs in modern and ancient marine environments is required. [...]."

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Source: Biogeosciences
Authors: Qixing Ji et al.
DOI: 10.5194/bg-16-2079-2019

Abstract

"The open ocean is a major source of nitrous oxide (N₂O), an atmospheric trace gas attributable to global warming and ozone depletion. Intense sea-to-air N₂O fluxes occur in major oceanic upwelling regions such as the eastern tropical South Pacific (ETSP). The ETSP is influenced by the El Niño–Southern Oscillation that leads to inter-annual variations in physical, chemical, and biological properties in the water column. In October 2015, a strong El Niño event was developing in the ETSP; we conduct field observations to investigate (1) the N₂Oproduction pathways and associated biogeochemical properties and (2) the effects of El Niño on water column N₂O distributions and fluxes using data from previous non-El Niño years. [...]."

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Source: Nature
Authors: Kanae Kobayashi et al.
DOI: 10.1038/s41396-019-0440-x

Abstract

"Natural abundance of stable nitrogen (N) and oxygen (O) isotopes are invaluable biogeochemical tracers for assessing the N transformations in the environment. To fully exploit these tracers, the N and O isotope effects (¹⁵ε and ¹⁸ε) associated with the respective nitrogen transformation processes must be known. [...]."

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Source: Nature 
Authors: Sakae Toyoda et al.
DOI: 10.1038/s41598-019-44224-0

Abstract

"Nitrous oxide (N₂O) contributes to global warming and stratospheric ozone depletion. Although its major sources are regarded as bacterial or archaeal nitrification and denitrification in soil and water, the origins of ubiquitous marine N₂O maximum at depths of 100–800 m and N₂O dissolved in deeper seawater have not been identified. [...]."

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Source: Wiley Online Library
Authors: Julius J.M. Busecke et al.
DOI: 10.1029/2019GL082692

Abstract

"Warming‐driven expansion of the oxygen minimum zone (OMZ) in the equatorial Pacific would bring very low oxygen waters closer to the ocean surface, and possibly impact global carbon/nutrient cycles and local ecosystems. Global coarse Earth System Models (ESMs) show, however, disparate trends that poorly constrain these future changes in the upper OMZ. [...]."

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

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). [...]."

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Source: Nature
Authors: J. Yang et al.
DOI: 10.1038/s41561-019-0371-1

Abstract

"The bioavailability of essential nutrients such as nitrogen and phosphorus has fluctuated with the chemical evolution of Earth surface environments over geological timescales. However, significant uncertainty remains over the evolution of Earth’s early nitrogen cycle, particularly how and when it responded to the evolution of oxygenic photosynthesis. [...]."

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

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. [...]."

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Source: Wiley Online Library
Authors: A. Bahl et al.
DOI: 10.1029/2018GB006121

Abstract

"Modern Earth System Models (ESMs) disagree on the impacts of anthropogenic global warming on the distribution of oxygen and associated low‐oxygen waters. A sensitivity study using the GFDL CM2Mc model points to the representation of lateral mesoscale eddy transport as a potentially important factor in such disagreement. Because mesoscale eddies are smaller than the spatial scale of ESM ocean grids, their impact must be parameterized using a lateral mixing coefficient A_REDI. [...]."

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

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. [...]."

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Source: Journal of Experimental Biology
Auhtors: Lillian R. McCormick et al. 
DOI: 10.1242/jeb.200899

Abstract

"For many animals, evolution has selected for complex visual systems despite the high energetic demands associated with maintaining eyes and their processing structures. The metabolic demands of visual systems therefore make them highly sensitive to fluctuations in available oxygen. In the marine environment, oxygen changes over daily, seasonal, and inter-annual time scales and there are large gradients of oxygen with depth. [...]."

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Source: PNAS
Authors: Daniel A. Stolper & Claire E. Bucholz
DOI: 10.1073/pnas.1821847116

Abstract

"A rise in atmospheric O₂ levels between 800 and 400 Ma is thought to have oxygenated the deep oceans, ushered in modern biogeochemical cycles, and led to the diversification of animals. Over the same time interval, marine sulfate concentrations are also thought to have increased to near-modern levels. We present compiled data that indicate Phanerozoic island arc igneous rocks are more oxidized (Fe³⁺/ΣFe ratios are elevated by 0.12) vs. Precambrian equivalents. [...]."

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Source: Wiley Online Library
Authors: Z. Lachkar et al.
DOI: 10.1029/2018GL081631

Abstract

"The highly saline, oxygen saturated waters of the Arabian Gulf (hereafter the Gulf) sink to intermediate depths (200‐300m) when they enter the Arabian Sea, ventilating the World's thickest oxygen minimum zone (OMZ). Here, we investigate the impacts of a warming of the Gulf consistent with climate change projections on the intensity of this OMZ. Using a series of eddy‐resolving model simulations, we show that the warming of the Gulf waters increases their buoyancy and hence limits their contribution to the ventilation of intermediate depths. [...]."

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Source: EurekAlert

"The world's oceans soak up about a quarter of the carbon dioxide that humans pump into the air each year -- a powerful brake on the greenhouse effect. In addition to purely physical and chemical processes, a large part of this is taken up by photosynthetic plankton as they incorporate carbon into their bodies. When plankton die, they sink, taking the carbon with them. Some part of this organic rain will end up locked into the deep ocean, insulated from the atmosphere for centuries or more. [...]."

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Source: PNAS
Authors: Jaclyn K. Saunders et al.
DOI: 10.1073/pnas.1818349116

Abstract

"Marine oxygen-deficient zones (ODZs) are naturally occurring midlayer oxygen-poor regions of the ocean, sandwiched between oxygenated surface and deep layers. In the absence of oxygen, microorganisms in ODZs use other compounds, such as oxidized forms of nitrogen and sulfur, as terminal electron acceptors. [...]."

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Source: Science
Authors: Emma R. Kast et al.
DOI: 10.1126/science.aau5784

Abstract

"The million-year variability of the marine nitrogen cycle is poorly understood. Before 57 million years (Ma) ago, the ¹⁵N/¹⁴N ratio (δ¹⁵N) of foraminifera shell-bound organic matter from three sediment cores was high, indicating expanded water column suboxia and denitrification. [...]."

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Source: PLOS
Authors: Lauren Gillies Campbell et al.
DOI: 10.1371/journal.pone.0209055

Abstract

"Rich geochemical datasets generated over the past 30 years have provided fine-scale resolution on the northern Gulf of Mexico (nGOM) coastal hypoxic (≤ 2 mg of O₂ L^-1) zone. In contrast, little is known about microbial community structure and activity in the hypoxic zone despite the implication that microbial respiration is responsible for forming low dissolved oxygen (DO) conditions. [...]."

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Source: Biogeosciences
Authors: Angélique Hameau et al. 
DOI: 10.5194/bg-16-1755-2019

Abstract

"Marine deoxygenation and anthropogenic ocean warming are observed and projected to intensify in the future. These changes potentially impact the functions and services of marine ecosystems. A key question is whether marine ecosystems are already or will soon be exposed to environmental conditions not experienced during the last millennium. Using a forced simulation with the Community Earth System Model (CESM) over the period 850 to 2100, we find that anthropogenic deoxygenation and warming in the thermocline exceeded natural variability in, respectively, 60 % and 90 % of total ocean area. [...]."

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Source: Biogeosciences
Authors: Soeren Thomsen et al.
DOI: 10.5194/bg-16-979-2019

Abstract

"Upwelling systems play a key role in the global carbon and nitrogen cycles and are also of local relevance due to their high productivity and fish resources. To capture and understand the high spatial and temporal variability in physical and biogeochemical parameters found in these regions, novel measurement techniques have to be combined in an interdisciplinary manner. Here we use high-resolution glider-based physical–biogeochemical observations in combination with ship-based underwater vision profiler, sensor and bottle data to investigate the drivers of oxygen and nitrate variability across the shelf break off Mauritania in June 2014. [...]."

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Source: Wiley Online Library
Authors: D. L. Arévalo‐Martínez et al.
DOI: 10.1029/2018GL081648

Abstract

"The Benguela Upwelling System (BUS) is the most productive of all eastern boundary upwelling ecosystems and it hosts a well‐developed oxygen minimum zone. As such, the BUS is a potential hotspot for production of N₂O, a potent greenhouse gas derived from microbially driven decay of sinking organic matter. Yet, the extent at which near‐surface waters emit N₂O to the atmosphere in the BUS is highly uncertain. [...]."

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Source: Nature
Authors: Mojtaba Fakhraee et al.
DOI: 10.1038/s41561-019-0351-5

Abstract

"Oceanic sulfate concentrations are widely thought to have reached millimolar levels during the Proterozoic Eon, 2.5 to 0.54 billion years ago. Yet the magnitude of the increase in seawater sulfate concentrations over the course of the Eon remains largely unquantified. A rise in seawater sulfate concentrations has been inferred from the increased range of marine sulfide δ³⁴S values following the Great Oxidation Event and was induced by two processes: enhanced oxidative weathering of sulfides on land, and the onset of marine sulfur redox cycling. [...]."

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Source: Wiley Online Library
Authors: Matthew B. Alkire et al. 
DOI: 10.1029/2018GL081837

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. [...]."

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Source: Nature
Authors: Philip W. Boyd et al.
DOI: 10.1038/s41586-019-1098-2

Abstract

"The ocean’s ability to sequester carbon away from the atmosphere exerts an important control on global climate. The biological pump drives carbon storage in the deep ocean and is thought to function via gravitational settling of organic particles from surface waters. However, the settling flux alone is often insufficient to balance mesopelagic carbon budgets or to meet the demands of subsurface biota. [...]."

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Source: Science Direct
Authors: Madeleine M. Nilsson et al.
DOI: 10.1016/j.marchem.2018.11.004

Abstract

"In situ measured benthic fluxes of dissolved inorganic carbon (DIC), a proxy for organic carbon (OC) oxidation or recycling rates, are used together with burial rates based on measured sediment accumulation rates (SAR) and vertical distribution of OC in the sediment solid phase to construct a benthic OC budget for the Baltic Sea system. [...]."

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Source: Xinhua 

"COLOMBO, April 11 (Xinhua) -- Sri Lanka's Marine Environment Protection Authority on Thursday urged countries along the Bay of Bengal to draft stronger laws against polluting the oceans due to the formation of a dead zone in the center of the Bay of Bengal. General Manager of the Marine Environment Protection Authority, Dr. P.B. Teney told Xinhua that authorities had discovered the formation of a dead zone in the Bay of Bengal which had spread across a 6000 square kilometer area and was 100 meters to 400 meters in depth. [...]."

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Source: Royal Society of Chemistry
Authors: Jian Zeng et al. 
DOI: 10.1039/C8EM00558C

Abstract

"Both dissolved and particulate organic materials have been proposed to be important factors in regulating the heterotrophic denitrification in various aquatic environments. However, specific pathways and mechanisms remain elusive. In this study, water column samples were collected from Daya Bay, southern China, to examine the relationships between potential denitrification and different organic components in the water column. Bulk dissolved organic carbon (DOC) was categorized into three major components including terrigenous fluorescent (tFDOC), autochthonous fluorescent (bFDOC) and non-fluorescent (nFDOC) fractions, while the bulk particulate organic carbon (POC) was divided into terrigenous (tPOC) and autochthonous (bPOC) based on an isotope mixing model. [...]."

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Source: Nature
Authors: Bruno Basso et al.
DOI: 10.1038/s41598-019-42271-1

Abstract

"Loss of reactive nitrogen (N) from agricultural fields in the U.S. Midwest is a principal cause of the persistent hypoxic zone in the Gulf of Mexico. We used eight years of high resolution satellite imagery, field boundaries, crop data layers, and yield stability classes to estimate the proportion of N fertilizer removed in harvest (NUE) versus left as surplus N in 8 million corn (Zea mays) fields at subfield resolutions of 30 × 30 m (0.09 ha) across 30 million ha of 10 Midwest states. [...]."

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Source: Frontiers in Marine Science
Authors: Kathleen Bailey et al.
DOI: 10.3389/fmars.2019.00180

Abstract

"Instrumented moorings (hereafter referred to as moorings), which are anchored buoys or an anchored configuration of instruments suspended in the water column, are highly valued for their ability to host a variety of interchangeable oceanographic and meteorological sensors. This flexibility makes them a useful technology for meeting end user and science-driven requirements. [...]."

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Source: Journal of Experimental Biology
Author: Yangfan Zhang
DOI: 10.1242/jeb.199141

"Hypoxia, a low level of oxygen that limits the physiological functions of animals, is a topic that fascinates many biologists. As climate change progresses, the frequency of hypoxic episodes in aquatic environments is increasing, putting fish species under stress and even reducing populations in some cases. But it is not only fish that suffer the ill effects of hypoxia. [...]."

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Source: Taylor & Francis Online
Authors: Kunal Chakraborty et al.
DOI: 10.1080/1755876X.2019.1588697

Abstract

"The resolution of the model emerges to be an important factor in simulating the real oceanic features. In this paper, the performance of two coupled bio-physical models, having spatial resolutions 1/12° (∼9 km) and 1/4° (∼25 km) configured using Regional Ocean Modeling System (ROMS), have been evaluated in simulating upper ocean dynamics of the Arabian Sea. [...]."

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Source: Biogeosciences
Authors: Katja Fennel et al.
DOI: 10.5194/bg-16-1281-2019

Abstract

"A quantification of carbon fluxes in the coastal ocean and across its boundaries with the atmosphere, land, and the open ocean is important for assessing the current state and projecting future trends in ocean carbon uptake and coastal ocean acidification, but this is currently a missing component of global carbon budgeting. This synthesis reviews recent progress in characterizing these carbon fluxes for the North American coastal ocean. [...]."

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Source: PNAS
Authors: Justin L. Penn et al.
DOI: 10.1073/pnas.1818014116

Abstract

"The dynamics of nitrogen (N) loss in the ocean’s oxygen-deficient zones (ODZs) are thought to be driven by climate impacts on ocean circulation and biological productivity. Here we analyze a data-constrained model of the microbial ecosystem in an ODZ and find that species interactions drive fluctuations in local- and regional-scale rates of N loss, even in the absence of climate variability. [...]."

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Source: Science Direct
Authors: Andrew C. Ross & Charles A. Stock
DOI: 10.1016/j.ecss.2019.03.007

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. [...]."

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Source: PNAS
Authors: Frantz Ossa Ossa et al.
DOI: 10.1073/pnas.1818762116

Abstract

"The Archean Eon was a time of predominantly anoxic Earth surface conditions, where anaerobic processes controlled bioessential element cycles. In contrast to “oxygen oases” well documented for the Neoarchean [2.8 to 2.5 billion years ago (Ga)], the magnitude, spatial extent, and underlying causes of possible Mesoarchean (3.2 to 2.8 Ga) surface-ocean oxygenation remain controversial. [...]."

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Source: Biogeosciences
Authors: Karin F. Kvale et al.
DOI: 10.5194/bg-16-1019-2019

Abstract

"Phytoplankton calcifiers contribute to global carbon cycling through their dual formation of calcium carbonate and particulate organic carbon (POC). The carbonate might provide an efficient export pathway for the associated POC to the deep ocean, reducing the particles' exposure to biological degradation in the upper ocean and increasing the particle settling rate. Previous work has suggested ballasting of POC by carbonate might increase in a warming climate, in spite of increasing carbonate dissolution rates, because calcifiers benefit from the widespread nutrient limitation arising from stratification. [...]."

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

Abstract

"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. [...]."

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Source: Nature
Authors: Shelly A. Wanamaker et al.
DOI: 10.1038/s41598-019-46947-6

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. [...]."

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Source: Nature
Authors: Adam J. Kessler et al.
DOI: 10.1038/s41564-019-0391-z

Abstract

"Permeable (sandy) sediments cover half of the continental margin and are major regulators of oceanic carbon cycling. The microbial communities within these highly dynamic sediments frequently shift between oxic and anoxic states, and hence are less stratified than those in cohesive (muddy) sediments. A major question is, therefore, how these communities maintain metabolism during oxic–anoxic transitions. [...]."

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Source: Nature 
Authors: Y. Isaji et al.
DOI: 10.1038/s41598-019-40174-9

Abstract

"The biogeochemistry of hypersaline environments is strongly influenced by changes in biological processes and physicochemical parameters. Although massive evaporation events have occurred repeatedly throughout Earth history, their biogeochemical cycles and global impact remain poorly understood. Here, we provide the first nitrogen isotopic data for nutrients and chloropigments from modern shallow hypersaline environments (solar salterns, Trapani, Italy) and apply the obtained insights to δ¹⁵N signatures of the Messinian salinity crisis (MSC) in the late Miocene. [...]."

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Source: Science Daily

"A new study suggests that measuring the volume rather than the area of the Gulf of Mexico's dead zone is more appropriate for monitoring its effects on marine organisms. [...]."

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Source: Scientific American
Author: Laura Poppick

"Escaping predators, digestion and other animal activities—including those of humans—require oxygen. But that essential ingredient is no longer so easy for marine life to obtain, several new studies reveal. In the past decade ocean oxygen levels have taken a dive—an alarming trend that is linked to climate change, says Andreas Oschlies, an oceanographer at the Helmholtz Center for Ocean Research Kiel in Germany, whose team tracks ocean oxygen levels worldwide. “We were surprised by the intensity of the changes we saw, how rapidly oxygen is going down in the ocean and how large the effects on marine ecosystems are,” he says. [...]."

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Source: Science Direct
Authors: Ruifang C. Xie et al.
DOI: 10.1016/j.epsl.2019.02.001

Abstract

"Over the past decades, observations have confirmed decreasing oxygen levels and shoaling of oxygen minimum zones (OMZs) in the tropical oceans. Such changes impact the biogeochemical cycling of micronutrients such as Cd, but the potential consequences are only poorly constrained. Here, we present seawater Cd concentrations and isotope compositions for 12 depth profiles at coastal, nearshore and offshore stations from 4°S to 14°S in the eastern tropical South Pacific, where one of the world's strongest OMZs prevails. [...]."

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Source: Wiley Online Library
Authors: Frederike Korth et al.
DOI: 10.1029/2018GL080466

Abstract

"Hydroxylamine (NH₂OH), a short‐lived intermediate in the nitrogen cycle, is a potential precursor of nitrous oxide (N₂O) in the ocean. However, measurements of NH₂OH in the ocean are sparse. Here we present a data set of depth profiles of NH₂OH from the equatorial Atlantic Ocean and the eastern tropical South Pacific and compare it to N₂O, nitrate, and nitrite profiles under varying oxygen conditions. The presence of NH₂OH in surface waters points toward surface nitrification in the upper 100 m. [...]."

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Source: Scientific American
Author: Erica Gies

"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. [...]."

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

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. [...]."

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Source: PNAS
Authors: Nicolaas Glock et al.
DOI: 10.1073/pnas.1813887116

Abstract

"Benthic foraminifera populate a diverse range of marine habitats. Their ability to use alternative electron acceptors—nitrate (NO3−) or oxygen (O2)—makes them important mediators of benthic nitrogen cycling. Nevertheless, the metabolic scaling of the two alternative respiration pathways and the environmental determinants of foraminiferal denitrification rates are yet unknown. We measured denitrification and O2 respiration rates for 10 benthic foraminifer species sampled in the Peruvian oxygen minimum zone (OMZ). [...]."

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Source: Biogeosciences
Authors: Darci Rush et al.
DOI: 10.5194/bg-16-2467-2019

Abstract

"The eastern Mediterranean Sea sedimentary record is characterised by intervals of organic rich sediment (sapropels), indicating periods of severe anoxia triggered by astronomical forcing. It has been hypothesized that nitrogen fixation was crucial in injecting the Mediterranean Sea with bioavailable nitrogen (N) during sapropel events. However, the evolution of the N biogeochemical cycle of sapropels is poorly understood. For example, the role of the complementary removal reaction, anaerobic ammonium oxidation (anammox), has not been investigated because the traditional lipid biomarkers for anammox, ladderane fatty acids, are not stable over long periods in the sedimentary record. [...]."

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

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. [...]."

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Source: Science Daily

"Climate change is causing significant changes to phytoplankton in the world's oceans, and a new MIT study finds that over the coming decades these changes will affect the ocean's color, intensifying its blue regions and its green ones. Satellites should detect these changes in hue, providing early warning of wide-scale changes to marine ecosystems. [...]."

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Source: Nature 
Authors: Stephanie Dutkiewicz et al.
DOI: 10.1038/s41467-019-08457-x

Abstract

"Marine calcifiers are considered to be among the most vulnerable taxa to climate-forced environmental changes occurring on continental margins with effects hypothesized to occur on microstructural, biomechanical, and geochemical properties of carbonate structures. Natural gradients in temperature, salinity, oxygen, and pH on an upwelling margin combined with the broad depth distribution (100–1,100 m) of the pink fragile sea urchin, Strongylocentrotus (formerly Allocentrotus) fragilis, along the southern California shelf and slope provide an ideal system to evaluate potential effects of multiple climate variables on carbonate structures in situ. [...]."

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Source: Wiley Online Library
Authors: Olaf Duteil
DOI: 10.1029/2018GL081041

Abstract

"The mechanisms controlling the variability of oxygen levels in the ocean are poorly quantified. We focus here on the impact of wind synoptic variability associated with tropical convective regions and extra‐tropical storms. Removing the wind higher frequencies of variability (2 days – 1 month) in an atmosphere reanalysis used to force an ocean model decreases wind stress by up to 20% in the tropics and 50% in the mid‐latitudes, weakening wind‐driven ocean circulation by 20%. Oxygen levels decrease by up to 10 mmol.m^‐3 in tropical oceans and 30 mmol.m^‐3 in subtropical gyres mainly due to changes in advective processes. [...]."

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Source: Wiley Online Library
Authors: Robert F. Anderson et al.
DOI: 10.1029/2018GB006049

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. [...]."

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Source: Oxford University Press
Authors: Jiapeng Wu et al.
DOI: 10.1093/femsec/fiz013

Abstract

"Candidatus Scalindua is an exclusive genus of anammox bacteria known to exhibit low diversity found in deep-sea ecosystems. In this study, the community composition of anammox bacteria in surface sediments of the South China Sea (SCS) was analyzed using high-throughput sequencing techniques. Results indicated that the dominant OTUs were related to three different genera of anammox bacteria, identified as Ca. Scalindua (87.29%), Ca. Brocadia (10.27%) and Ca. Kuenenia (2.44%), in order of decreasing abundance. [...]."

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Source: Frontiers in Marine Science
Authors: Céline C. Michiels et al.
DOI: 10.3389/fmars.2019.00027

Abstract

"Marine oxygen minimum zones (OMZs) support 30-50% of global fixed-nitrogen (N) loss but comprise only 7% of total ocean volume. This N-loss is driven by canonical denitrification and anaerobic ammonium oxidation (anammox), and the distribution and activity of these two processes vary greatly in space and time. Factors that regulate N-loss processes are complex, including organic matter availability, oxygen concentrations, and NO2- and NH4+ concentrations. [...]."

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Source: Science Direct
Authors: Elfi Mollier-Vogel et al.
DOI: 10.1016/j.gloplacha.2018.10.020

Abstract

"This study presents new high resolution sedimentary δ15N records from piston cores collected within and outside the present-day eastern south Pacific oxygen minimum zone along a latitudinal transect from 3.5°S to 15°S. Radiocarbon dating of foraminifera and organic matter show that the cores cover the Holocene and the last deglaciation with high sedimentation rate allowing interpretations at millennial to centennial timescale. [...]."

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Source: Frontiers in Marine Science
Authors: Carolina Cisternas-Novoa et al.
DOI: 10.3389/fmars.2018.00500

Abstract

"We investigated how future ocean conditions, and specifically the interaction between temperature and CO2, might affect marine aggregate formation and physical properties. Initially, mesocosms filled with coastal seawater were subjected to three different treatments of CO2 concentration and temperature: (1) 750 ppm CO2, 16°C, (2) 750 ppm CO2, 20°C, and (3) 390 ppm CO2, 16°C. Diatom-dominated phytoplankton blooms were induced in the mesocosms by addition of nutrients. [...]."

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Source: Science Direct
Authors: A.W. Dale et al.
DOI: 10.1016/j.gca.2018.10.025

Abstract

"Stable isotopes (15,14N, 18,16O) of dissolved inorganic nitrogen (N) were measured in sediment porewaters and benthic flux chambers across the Peruvian oxygen minimum zone (OMZ) from 74 to 1000 m water depth. Sediments at all locations were net consumers of bottom water NO3−. In waters shallower than 400 m, this sink was largely attributed to dissimilatory nitrate reduction to ammonium (DNRA) by filamentous nitrate-storing bacteria (Marithioploca and Beggiatoa) and to denitrification by foraminifera. [...]."

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Source: The Guardian
Author: Fiona Harvey

"A new global agreement to protect the seas should be a priority for the government to stop our seas becoming a “sewer”, according to a cross-party group of MPs. Plastic pollution is set to treble in the next decade, the environmental audit committee warned, while overfishing is denuding vital marine habitats of fish, and climate change is causing harmful warming of the oceans as well as deoxygenation and acidification. [...]."

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Source: Independent
Author: Josh Gabbatiss

"British seas are being treated “like a sewer”, polluted by an endless stream of plastics, untreated waste and farming effluent, MPs have warned. In a damning new report, the Environmental Audit Committee has laid out the dangers facing the nation’s oceans and what needs to be done to address them. Besides pollution, climate change, overfishing and deep sea mining are all threatening marine ecosystems and the trillions of pounds they deliver to the economy, the report states. [...]."

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Source: Science
Authors: Lijing Cheng et al
DOI: 10.1126/science.aav7619

Abstract

"Climate change from human activities mainly results from the energy imbalance in Earth's climate system caused by rising concentrations of heat-trapping gases. About 93% of the energy imbalance accumulates in the ocean as increased ocean heat content (OHC). The ocean record of this imbalance is much less affected by internal variability and is thus better suited for detecting and attributing human influences than more commonly used surface temperature records. Recent observation-based estimates show rapid warming of Earth's oceans over the past few decades (see the figure). [...]."

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Source: Wiley Online Library
Authors: Kenneth S. Johnson et al. 
DOI: 10.1029/2018GL079881

Abstract

"Nitrate limits productivity in much of the ocean. Nitrate residence time is a few thousand years and changes in nitrate loss could influence ocean productivity. A major sinks for nitrate is denitrification and anaerobic ammonia oxidation in the oxygen minimum zones (OMZs). The Bay of Bengal OMZ is anomalous because large amounts of nitrate loss do not occur there, while nitrate is removed in the nearby OMZ of the Arabian Sea. Observations of nitrate and oxygen made over 5 years by 20 profiling floats equipped with chemical sensors in the Bay of Bengal and the Arabian Sea are used to understand why nitrate is removed rapidly in the Arabian Sea, but not in the Bay of Bengal. [...]."

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Source: Wiley Online Library
Authors: Jeffrey Coogan et al.
DOI: 10.1029/2018JC014592

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. [...]."

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Source: GeoScienceWorld 
Authors: Stuart A. Robinson et al.
DOI: 10.1130/G45842.1

Abstract

"Mesozoic oceanic anoxic events (OAEs) were major perturbations of the Earth system, associated with high CO₂ concentrations in the oceans and atmosphere, high temperatures, and widespread organic-carbon burial. Models for explaining OAEs and other similar phenomena in Earth history make specific predictions about the role and pattern of temperature change, which can be tested through comparison with the geological record. Oceanic Anoxic Event 2 (OAE 2) occurred ~94 m.y. ago and is commonly considered as the type example of an OAE. [...]."

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Source: IOP Science
Authors: Donald Scavia et al.
DOI: 10.1088/1748-9326/aaf938

Abstract

"While impacts of low oxygen on marine organisms have been reviewed from physiological and ecological perspectives, relating broad population- and ecosystem-level effects to the areal extent of hypoxia (dissolved oxygen concentration below 64 µM, or 2 mg/l) has proven difficult. We suggest that hypoxic volume is a more appropriate metric compared to hypoxic area because volume better integrates the effects of hypoxia on ecological processes relevant to many marine taxa. [...]."

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Source: Science Direct
Authors: Huabing Xu et al.
DOI: 10.1016/j.scitotenv.2018.12.384

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. [...]."

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Source: Biogeosciences
Authors: Insa Rapp et al.
DOI: 10.5194/bg-2018-472

Abstract

"The availability of the micronutrient iron (Fe) in surface waters determines primary production, N₂ fixation and microbial community structure in large parts of the world's ocean, and thus plays an important role in ocean carbon and nitrogen cycles. Eastern boundary upwelling systems and the connected oxygen minimum zones (OMZs) are typically associated with elevated concentrations of redox-sensitive trace metals (e.g. Fe, manganese (Mn) and cobalt (Co)), with shelf sediments typically forming a key source. Over the last five decades, an expansion and intensification of OMZs has been observed and this trend is likely to proceed. [...]."

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Source: Science Direct
Authors: Feifei Zhang et al.
DOI: 10.1016/j.earscirev.2018.10.012

Abstract

"The Smithian-Spathian boundary (SSB) was an interval characterized by a major global carbon cycle perturbation, climatic cooling from a middle/late Smithian boundary hyperthermal condition, and a major setback in the recovery of marine necto-pelagic faunas from the end-Permian mass extinction. Although the SSB has been linked to changes in oceanic redox conditions, key aspects of this redox variation (e.g., duration, extent, and triggering mechanisms) and its relationship to coeval climatic and biotic changes remain unresolved. [...]."

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Source: Science Direct
Authors: Linping Xie et al.
DOI: 10.1016/j.scitotenv.2018.08.333

Abstract

"Blue holes can provide valuable information regarding paleoclimate, climate change, karst processes, marine ecology, and carbonate geochemistry. The Sansha Yongle Blue Hole, located on Yongle Atoll in the Paracel Islands in the South China Sea, is the deepest blue hole in the world. A comprehensive investigation of the blue hole was conducted to determine the hydrochemical properties and associated redox processes active in the water column. Results indicate the presence of two thermoclines, one at 13–20 m and a second at 70–150 m, dividing the water column into five stratified water layers. [...]."

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

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 (OMZ) in the world ocean where dissolved oxygen (O2) concentrations reach well below 1 µmol kg−1. The high productivity leads to an accumulation of dissolved organic matter (DOM) in the surface layers that may serve as a substrate for heterotrophic respiration. [...]."

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Source: Biogeosciences
Authors: Kristin Doering et al.
DOI: 10.5194/bg-16-2163-2019

Abstract

"The stable sedimentary nitrogen isotope compositions of bulk organic matter (δ¹⁵N_bulk) and the silicon isotope composition of diatoms (δ³⁰Si_BSi) both mainly reflect the degree of past nutrient utilization by primary producers. However, in ocean areas where anoxic and suboxic conditions prevail, the δ¹⁵N_bulk signal ultimately recorded within the sediments is also influenced by water column denitrification [...]."

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