Source: Wiley Online Library
Authors: Liuqian Yu et al.
DOI: 10.1002/lno.11616

Abstract

"Globally expanding hypoxia in estuaries and coastal oceans has largely been attributed to the elevated river nutrient inputs, whereas the role of river-delivered terrestrial organic matter (OMterr) in hypoxia formation has been less investigated. This study uses a coupled physical-biogeochemical model and observations to investigate how OMterr directly (via remineralization) and indirectly (via the nutrients released from OMterr remineralization) promotes hypoxia development in the coastal transition zone off the Pearl River Estuary. [...]."

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Source: Wiley Online Library
Authors: Guodong Song et al.
DOI: 10.1002/lno.11630

Abstract

"The effects of bottom water oxygen concentration on sediment oxygen uptake, oxygen penetration depth, nitrate and ammonium fluxes, anammox, denitrification, dissimilatory nitrate reduction to ammonium, nitrification, and mineralization were investigated off the Changjiang estuary and its adjacent East China Sea, by combining a seasonal comparison with three artificially induced bottom water oxygen conditions (oxic, ambient, and severe hypoxia). [...]."

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Source: Springer Link
Authors: Marco Bartoli et al.
DOI: 10.1007/s12237-020-00786-1

Abstract

"Harmful blooms of cyanobacteria may extend over long time spans due to self-sustaining mechanisms. We hypothesized that settled blooms may increase redox-dependent P release and unbalance the stoichiometry of benthic nutrient regeneration (NH4+:SiO2:PO43− ratios). We tested this hypothesis in the hypertrophic Curonian Lagoon, the largest in Europe. During summer, at peak chlorophyll and water temperatures, sediment cores were collected over 19 stations representing all the lagoon sedimentary environments. [...]."

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"The Global Ocean Oxygen Network (GO₂NE) webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment – ocean deoxygenation. Organised and hosted by IOC/UNESCO, each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 9 December 2020 No 2

Moderator:
Prof. Andreas Oschlies
GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany

Speakers:
Dr. Sören Thomsen
LOCEAN-IPSL, CNRS, Paris, France
"How fine-scale physical processes shape the oxycline off Peru"

Prof. Laure Resplandy
Princeton University, USA
"Will oxygen minimum zones expand or shrink? The crucial contributions of ocean mixing and biogeochemical feedbacks"

You can watch the GO₂NE Webinar 9 December 2020 No 2 recording here.

Source: Springer Link
Authors: Francesco De Leo et al.
DOI: 10.1007/s10236-020-01419-8

Abstract

"Wind-generated ocean waves are key inputs for several studies and applications, both near the coast (coastal vulnerability assessment, coastal structures design, harbor operativity) and off-shore (a.o. oil and gas production, ship routes, and navigation safety). As such, the evaluation of trends in future wave climate is fundamental for the development of efficient policies in the framework of climate change adaptation and mitigation measures. [...]."

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Source: Wiley Online Library
Authors: Jun Inoue et al.
DOI: 10.1029/2020JD033904

Abstract

"The presence of clouds in the Arctic regulates the surface energy budget (SEB) over the sea‐ice surface and the ice‐free ocean. Following several previous field campaigns, the cloud‐radiation relationship, including cloud vertical structure and phase, has been elucidated; however, modeling of this relationship has matured slowly. In recognition of the recent decline in the Arctic sea‐ice extent, representation of the cloud system in numerical models should consider the effects of areas covered by sea ice and ice‐free areas. [...]."

Read the full article here.

"The Global Ocean Oxygen Network (GO₂NE) webinar series is a regular online seminar series that focuses on the depletion of oxygen in the marine environment – ocean deoxygenation. Organised and hosted by IOC/UNESCO, each one-hour webinar is run by a guest moderator and two invited speakers. To support the diversity of the scientific community, the webinar series aims for an equal balance of early-career and senior scientists, gender, and geographical representation."

GO2NE Webinar 11 November 2020 No 1

Moderator:
Prof. Michael Roman
University of Maryland Center for Environmental Science, USA

Speakers:
Dr. Alexandra Steckbauer
King Abdullah University of Science and Technology, Kingdom of Saudi Arabia
"Defining O₂ and CO₂ syndromes in the ocean and how deoxygenation and acidification impact marine biota"

Prof. Karen Wishner
University of Rhode Island, USA
"Deoxygenation and zooplankton: distributional strategies and oxygen minimum zone variability"

You can watch the GO₂NE Webinar 11 November 2020 No 1 recording here.

Source: Nature  
Authors: Jan Taucher et al.
DOI: 10.1038/s41558-020-00915-5

Abstract

"Ocean acidification (OA) will affect marine biotas from the organism to the ecosystem level. Yet, the consequences for the biological carbon pump and thereby the oceanic sink for atmospheric CO2 are still unclear. Here we show that OA considerably alters the C/N ratio of organic-matter export (C/Nexport), a key factor determining efficiency of the biological pump. By synthesizing sediment-trap data from in situ mesocosm studies in different marine biomes, we find distinct but highly variable impacts of OA on C/N_export, reaching up to a 20% increase/decrease under partial pressure of CO₂ (pCO2) conditions projected for 2100. [...]."

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Source: Nature
Authors: Wenju Cai et al.
DOI: 10.1038/s41558-020-00943-1

Abstract

"A strong positive Indian Ocean Dipole (pIOD) induces weather extremes such as the 2019 Australian bushfires and African floods. The impact is influenced by sea surface temperature (SST), yet models disagree on how pIOD SST may respond to greenhouse warming. Here we find increased SST variability of strong pIOD events, with strong equatorial eastern Indian Ocean cool anomalies, but decreased variability of moderate pIOD events, dominated by western warm anomalies. [...]."

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Source: Wiley Online Library
Author: Colette L. Kelly et al.
DOI: 10.1029/2020GB006637

Abstract

"Nitrous oxide (N2O), a potent greenhouse gas, is produced disproportionately in marine oxygen deficient zones (ODZs). To quantify spatiotemporal variation in N2O cycling in an ODZ, we analyzed N2O concentration and isotopologues along a transect through the eastern tropical North Pacific (ETNP). At several stations along this transect, N2O concentrations reached a near surface maximum that exceeded prior measurements in this region, of up to 226.1 ± 20.5 nM at the coast. [...]."

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Source: MDPI
Authors: Cuen Muller et al.
DOI: 10.3390/oceans2010002

Abstract

"Ocean acidification is predicted to have widespread impacts on marine species. The early life stages of fishes, being particularly sensitive to environmental deviations, represent a critical bottleneck to recruitment. We investigated the effects of ocean acidification (∆pH = −0.4) on the oxygen consumption and morphometry during the early ontogeny of a commercially important seabream, Chrysoblephus laticeps, up until flexion. Hatchlings appeared to be tolerant to hypercapnic conditions, exhibiting no difference in oxygen consumption or morphometry between treatments, although the yolk reserves were marginally reduced in the low-pH treatment. [...]."

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Source: Nature  
Authors: Mojtaba Fakhraee et al.
DOI: 10.1038/s41561-020-00660-6

Abstract

"The biological pump—the transfer of atmospheric carbon dioxide to the ocean interior and marine sediments as organic carbon—plays a critical role in regulating the long-term carbon cycle, atmospheric composition and climate. Despite its centrality in the Earth system, the response of the biological pump to biotic innovation and climatic fluctuations through most stages of Earth’s history has been largely conjectural. Here we use a mechanistic model of the biological carbon pump to revisit the factors controlling the transfer efficiency of carbon from surface waters to the ocean interior and marine sediments. [...]."

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Source: Nature 
Authors: Julia Gottschalk et al.
DOI: 10.1038/s41467-020-20034-1

Abstract

"Past changes in ocean 14C disequilibria have been suggested to reflect the Southern Ocean control on global exogenic carbon cycling. Yet, the volumetric extent of the glacial carbon pool and the deglacial mechanisms contributing to release remineralized carbon, particularly from regions with enhanced mixing today, remain insufficiently constrained. Here, we reconstruct the deglacial ventilation history of the South Indian upwelling hotspot near Kerguelen Island, using high-resolution 14C-dating of smaller-than-conventional foraminiferal samples and multi-proxy deep-ocean oxygen estimates. [...]."

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Source: Nature 
Authors: H. J. T. Hoving et al.
DOI: 10.1038/s41598-020-78255-9

Abstract

"Distribution patterns of fragile gelatinous fauna in the open ocean remain scarcely documented. Using epi-and mesopelagic video transects in the eastern tropical North Atlantic, which features a mild but intensifying midwater oxygen minimum zone (OMZ), we established one of the first regional observations of diversity and abundance of large gelatinous zooplankton. We quantified the day and night vertical distribution of 46 taxa in relation to environmental conditions. [...]."

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Source: Science Direct
Authors: Sebastian G. Litchfield et al.
DOI: 10.1016/j.marpolbul.2020.111354

Abstract

"Plastic pollution and ocean change have mostly been assessed separately, missing potential interactions that either enhance or reduce future impacts on ecosystem processes. Here, we used manipulative experiments with outdoor mesocosms to test hypotheses about the interactive effects of plastic pollution, ocean warming and acidification on macrophyte detrital decomposition. These experiments focused on detritus from kelp, Ecklonia radiata, and eelgrass, Zostera muelleri, and included crossed treatments of (i) no, low and high plastic pollution, (ii) current/future ocean temperatures, and (iii) ambient/future ocean partial pressure of carbon dioxide (pCO2). [...]."

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Source: Nature 
Authors: Gaojing Fan et al.
DOI: 10.1038/s41598-020-70417-z 

Abstract

"Satellite remote sensing and numerical models are widely used to estimate large-scale variations in ocean carbon export, but the relationship between export efficiency (e-ratio) of sinking organic carbon out of the surface ocean and its drivers remains poorly understood, especially in the Southern Ocean. Here, we assess the effects of temperature and primary productivity on e-ratio by combining particulate organic carbon export flux from in situ measurements during 1997–2013, environmental parameters from satellite products, and outputs from ocean biogeochemical models in the Southern Ocean. Results show that “High Productivity Low E-ratio” (HPLE) is a common phenomenon in the Subantarctic Zone and the Polar Frontal Zone, but not the Antarctic Zone. [...]."

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Source: Science 
Authors: K. M. Lewis et al.
DOI: 10.1126/science.aay8380 

Abstract

"Historically, sea ice loss in the Arctic Ocean has promoted increased phytoplankton primary production because of the greater open water area and a longer growing season. However, debate remains about whether primary production will continue to rise should sea ice decline further. Using an ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018. [...]."

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Source: Frontiers in Marine Science
Authors: Pingyang Li & Toste Tanhua
DOI: 10.3389/fmars.2020.00594

Abstract

"The Mediterranean Sea is a small region of the global ocean but with a very active overturning circulation that allows surface perturbations to be transported to the interior ocean. Understanding of ventilation is important for understanding and predicting climate change and its impact on ocean ecosystems. To quantify changes of deep ventilation, we investigated the spatiotemporal variability of transient tracers (i.e., CFC-12 and SF6) observations combined with temporal evolution of hydrographic and oxygen observations in the Mediterranean Sea from 13 cruises conducted during 1987–2018, with emphasize on the update from 2011 to 2018. [...]."

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Source: Biogeosciences 
Authors: Tim Rixen et al.
DOI: 10.5194/bg-17-6051-2020

Abstract

"Decreasing concentrations of dissolved oxygen in the ocean are  fuconsidered one of the main threats to marine ecosystems as they jeopardize the growth of higher organisms. They also alter the marine nitrogen cycle, which is strongly bound to the carbon cycle and climate. While higher organisms in general start to suffer from oxygen concentrations < ∼ 63 µM (hypoxia), the marine nitrogen cycle responds to oxygen concentration below a threshold of about 20 µM (microbial hypoxia), whereas anoxic processes dominate the nitrogen cycle at oxygen concentrations of < ∼ 0.05 µM (functional anoxia). The Arabian Sea and the Bay of Bengal are home to approximately 21 % of the total volume of ocean waters revealing microbial hypoxia. [...]."

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Source: Biogeosciences
Authors: Amal Jayakumar & Bess B. Ward
DOI: 10.5194/bg-17-5953-2020

Abstract

"Diversity and community composition of nitrogen (N) fixing microbes in the three main oxygen minimum zones (OMZs) of the world ocean were investigated using operational taxonomic unit (OTU) analysis of nifH clone libraries. Representatives of three of the four main clusters of nifH genes were detected. Cluster I sequences were most diverse in the surface waters, and the most abundant OTUs were affiliated with Alpha- and Gammaproteobacteria. Cluster II, III, and IV assemblages were most diverse at oxygen-depleted depths, and none of the sequences were closely related to sequences from cultivated organisms. The OTUs were biogeographically distinct for the most part – there was little overlap among regions, between depths, or between cDNA and DNA. [...]."

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Source: Science Direct
Authors: Junna Wang & Zhonglong Zhang 
DOI: 10.1016/j.jenvman.2020.110233

Abstract

"Transport and fate of phytoplankton blooms and excessive nutrients along salinity and turbidity gradients of a river-estuary continuum could determine when and where impaired water quality occurs. However, the general spatiotemporal patterns, underlying mechanisms and their implication for water quality management are not well understood. This study reveals typical seasonal variations and longitudinal patterns of phytoplankton, dissolved oxygen (DO) and nutrients (C, N, and P) in the lower St. Johns River estuary in Florida based on 23 years of data and a model which spans 3 years. [...]."

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Source: Wiley Online Library
Authors: A.‐M. Hayden et al.
DOI: 10.1029/2019JC015104

Abstract

"Past and modern large‐scale ice sheet loss results in geographically variable sea level changes. At present, in Hudson Bay, Canada, sea level is decreasing due to glacial isostatic adjustment, which represents a departure from the globally averaged sea level rise. However, there are large uncertainties in future sea level trends with further polar ice sheet retreat in the coming centuries. Sea level changes affect ocean tides considerably because tides are highly sensitive to changes in bathymetry. Here, we present multi‐century sea level projections associated with a suite of past and future ice loss scenarios and consider the impact of these changes on ocean tides using an established tidal model. [...]."

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Source: Biogeosciences
Authors: Samuel T. Wilson et al.
DOI: 10.5194/bg-17-5809-2020

Abstract

"In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. [...]."

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Source: Nature 
Authors: Hana Jurikova et al.
DOI: 10.1038/s41561-020-00646-4

Abstract

"The Permian/Triassic boundary approximately 251.9 million years ago marked the most severe environmental crisis identified in the geological record, which dictated the onwards course for the evolution of life. Magmatism from Siberian Traps is thought to have played an important role, but the causational trigger and its feedbacks are yet to be fully understood. Here we present a new boron-isotope-derived seawater pH record from fossil brachiopod shells deposited on the Tethys shelf that demonstrates a substantial decline in seawater pH coeval with the onset of the mass extinction in the latest Permian. [...]."

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

Abstract

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

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Source: Nature
Authors: Ben Bronselaer & Laure Zanna 
DOI: 10.1038/s41586-020-2573-5

Abstract

Anthropogenic global surface warming is proportional to cumulative carbon emissions1,2,3; this relationship is partly determined by the uptake and storage of heat and carbon by the ocean4. The rates and patterns of ocean heat and carbon storage are influenced by ocean transport, such as mixing and large-scale circulation5,6,7,8,9,10. However, existing climate models do not accurately capture the observed patterns of ocean warming, with a large spread in their projections of ocean circulation and ocean heat uptake8,11. Additionally, assessing the influence of ocean circulation changes (specifically, the redistribution of heat by resolved advection) on patterns of observed and simulated ocean warming remains a challenge. [...]."

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Source: Wiley Online Library
Authors: Judith Piontek et al.
DOI: 10.1002/lno.11639

Abstract

"The Arctic Ocean is highly susceptible to climate change as evidenced by rapid warming and the drastic loss of sea ice during summer. The consequences of these environmental changes for the microbial cycling of organic matter are largely unexplored. Here, we investigated the distribution and composition of dissolved organic matter (DOM) along with heterotrophic bacterial activity in seawater and sea ice of the Eurasian Basin at the time of the record ice minimum in 2012. Bacteria in seawater were highly responsive to fresh organic matter and remineralized on average 55% of primary production in the upper mixed layer. [...]."

Read the full article here.

Source: Nature 
Authors: Laurie C. Menviel et al.
DOI: 10.1038/s43017-020-00106-y

Abstract

"Intermediate glacial states were characterized by large temperature changes in Greenland and the North Atlantic, referred to as Dansgaard–Oeschger (D–O) variability, with some transitions occurring over a few decades. D–O variability included changes in the strength of the Atlantic meridional overturning circulation (AMOC), temperature changes of opposite sign and asynchronous timing in each hemisphere, shifts in the mean position of the Intertropical Convergence Zone and variations in atmospheric CO2. [...]."

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Source: Nature
Authors: Nicholas Robert Bates et al.
DOI: 10.1038/s43247-020-00030-5

Abstract

"Ocean chemical and physical conditions are changing. Here we show decadal variability and recent acceleration of surface warming, salinification, deoxygenation, carbon dioxide (CO2) and acidification in the subtropical North Atlantic Ocean (Bermuda Atlantic Time-series Study site; 1980s to present). Surface temperatures and salinity exhibited interdecadal variability, increased by ~0.85 °C (with recent warming of 1.2 °C) and 0.12, respectively, while dissolved oxygen levels decreased by ~8% (~2% per decade). [...]."

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Source: Wiley Online Library
Authors: Esther Portela et al.
DOI: 10.1029/2020GL089040

Abstract

"Future changes in subduction are suspected to be critical for the ocean deoxygenation predicted by climate models over the 21st century. However, the drivers of global oxygen subduction have not been fully described or quantified. Here, we address the physical mechanisms responsible for the oxygen transport across the late‐winter mixed layer base and their relation with water mass formation. Up to 70% of the global oxygen uptake takes place during Mode Water subduction mostly in the Southern Ocean and the North Atlantic. [...]."

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Source: Wiley Online Library
Authors: Jianzhong Su et al.
DOI: 10.1002/lno.11419

Abstract

"We surveyed the carbonate system along the main channel of the Chesapeake Bay in June 2016 to elucidate carbonate dynamics and the associated sources of oxygen‐consuming organic matter. Using a two endmember mixing calculation, chemical proxies, and stoichiometry, we demonstrated that in early summer, dissolved inorganic carbon (DIC) dynamics were controlled by aerobic respiration in the water column (43%), sulfate reduction in the sediment (39%), atmospheric CO2 invasion (13%), and CaCO3 dissolution (5%). [...]."

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Source: Science Direct
Authors: Philipp Nasemann et al.
DOI: 10.1016/j.gca.2020.06.027

Abstract

"The marine chromium (Cr) cycle is still insufficiently understood, in particular the mechanisms modulating the spatial distribution of dissolved stable Cr isotopes in seawater. Redox transformations between its main oxidation states, Cr(VI) and Cr(III), have been held accountable for the observed tight inverse logarithmic relationship between the dissolved Cr concentration [Cr] and its isotopic composition (δ53Cr), whereby isotopically light Cr(III) is removed in surface waters and oxygen minimum zones (OMZs), and subsequently released to deeper waters from remineralized particles or sediments. [...]."

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Source: Wiley Online Library
Authors: Malika Kheireddine et al.
DOI: 10.1029/2020GB006650

Abstract

"The export and fate of organic carbon in the mesopelagic zone are still poorly understood and quantified due to lack of observations. We exploited data from a biogeochemical‐Argo float that was deployed in the Red Sea to study how a warm and hypoxic environment can affect the fate of the organic carbon in the ocean's interior. We observed that only 10% of the particulate organic carbon (POC) exported survived at depth due to remineralization processes in the upper mesopelagic zone. [...]."

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Source: Nature 
Authors: Guancheng Li  et al.
DOI: 10.1038/s41558-020-00918-2

Abstract

"Seawater generally forms stratified layers with lighter waters near the surface and denser waters at greater depth. This stable configuration acts as a barrier to water mixing that impacts the efficiency of vertical exchanges of heat, carbon, oxygen and other constituents. Previous quantification of stratification change has been limited to simple differencing of surface and 200-m depth changes and has neglected the spatial complexity of ocean density change. [...]."

Read the full article here.

Source: GeoScienceWorld
Authors: Christopher T. Reinhard et al.
DOI: 10.2138/gselements.16.3.191

Abstract

"The redox state of Earth’s atmosphere has undergone a dramatic shift over geologic time from reducing to strongly oxidizing, and this shift has been coupled with changes in ocean redox structure and the size and activity of Earth’s biosphere. Delineating this evolutionary trajectory remains a major problem in Earth system science. Significant insights have emerged through the application of redox-sensitive geochemical systems. [...]."

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Source: Science Direct
Authors: Clare E. Reimers et al.
DOI: 10.1016/j.ecss.2020.106815

Abstract

"Benthic habitats within fjords are predominantly insulated from the high energy physical dynamics of open coastlines. As a result, fjords may have atypical mass and heat transfer rates at the seafloor. This study presents aquatic eddy covariance (EC) measurements made continuously from late May 2013 through December 2013, in Saanich Inlet fjord, British Columbia, to assess areal-averaged benthic fluxes of dissolved oxygen and heat, and their relationships to bottom boundary layer dynamics and water properties. [...]."

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Source: Biogeosciences
Authors: Lennart Thomas Bach et al.
DOI: 10.5194/bg-17-4831-2020

Abstract

"Eastern boundary upwelling systems (EBUS) are among the most productive marine ecosystems on Earth. The production of organic material is fueled by upwelling of nutrient-rich deep waters and high incident light at the sea surface. However, biotic and abiotic factors can modify surface production and related biogeochemical processes. Determining these factors is important because EBUS are considered hotspots of climate change, and reliable predictions of their future functioning requires understanding of the mechanisms driving the biogeochemical cycles therein. In this field experiment, we used in situ mesocosms as tools to improve our mechanistic understanding of processes controlling organic matter cycling in the coastal Peruvian upwelling system. [...]."

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Source: Wiley Online Library
Authors: Niels A. G. M. van Helmond et al.
DOI: 10.1002/lno.11575

Abstract

"Enhanced nutrient input and warming have led to the development of low oxygen (hypoxia) in coastal waters globally. For many coastal areas, insight into redox conditions prior to human impact is lacking. Here, we reconstructed bottom water redox conditions and sea surface temperatures (SSTs) for the coastal Stockholm Archipelago over the past 3000 yr. [...]."

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Source: Science Direct
Authors: Bernd Christiansen et al.
DOI: 10.1016/j.marpol.2019.02.014

Abstract

"Environmental concerns were raised from the very onset of discussions concerning the extraction of metalliferous ores from the deep sea, but most studies have targeted the expected impacts on the benthic communities only. The first section of this study compiles possible impacts of deep seabed mining activities on pelagic organisms. Several processes of mining-related activities were identified that can potentially affect the pelagic environment. Some of these processes will assumedly have only minor effects on the pelagic and benthopelagic communities, for example substrate removal and deposition of material. [...]."

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Source: Science Direct
Authors: Halina Kendzierska et al.
DOI: 10.1016/j.jembe.2020.151439

Abstract

"Understanding the role of benthic organisms in marine sediments is becoming increasingly important with the growing problem of eutrophication of marine ecosystems around the world, including the Baltic Sea. Therefore, we have conducted a series of incubation experiments on sediment cores collected from sites characterized by varying oxygen conditions and measured the influx (uptake by sediment) of oxygen as well as the sediment–water exchange of phosphate, ammonia and silicate. [...]."

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Source: Wiley Online Library
Authors: J. Michael Berman et al.
DOI: 10.1111/1462-2920.15215

Abstract

"Oceanic oxygen minimum zones (OMZs) play a pivotal role in biogeochemical cycles due to extensive microbial activity. How OMZ microbial communities assemble and respond to environmental variation is therefore essential to understanding OMZ functioning and ocean biogeochemistry. Sampling along depth profiles at five stations in the eastern tropical North Pacific Ocean (ETNP), we captured systematic variations in dissolved oxygen (DO) and associated variables (nitrite, chlorophyll, and ammonium) with depth and between stations. We quantitatively analysed relationships between oceanographic gradients and microbial community assembly and activity based on paired 16S rDNA and 16S rRNA sequencing. [...]."

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Source: Annual Reviews
Authors: Scott C. Doney et al.
DOI: 10.1146/annurev-environ-012320-083019

Abstract

"Rising atmospheric carbon dioxide (CO2) levels, from fossil fuel combustion and deforestation, along with agriculture and land-use practices are causing wholesale increases in seawater CO2 and inorganic carbon levels; reductions in pH; and alterations in acid-base chemistry of estuarine, coastal, and surface open-ocean waters. On the basis of laboratory experiments and field studies of naturally elevated CO2 marine environments, widespread biological impacts of human-driven ocean acidification have been posited, ranging from changes in organism physiology and population dynamics to altered communities and ecosystems. [...]."

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Source: Nature 
Authors: Mingyu Zhao et al.
DOI: 10.1038/s41467-020-15673-3

Abstract

"The marine phosphorus cycle plays a critical role in controlling the extent of global primary productivity and thus atmospheric pO2 on geologic time scales. However, previous attempts to model carbon–phosphorus-oxygen feedbacks have neglected key parameters that could shape the global P cycle. Here we present new diagenetic models to fully parameterize marine P burial. We have also coupled this diagenetic framework to a global carbon cycle model. [...]."

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Source: Nature
Authors: Curtis Deutsch et al.
DOI: 10.1038/s41586-020-2721-y

Abstract

"Climate and physiology shape biogeography, yet the range limits of species can rarely be ascribed to the quantitative traits of organisms1,2,3. Here we evaluate whether the geographical range boundaries of species coincide with ecophysiological limits to acquisition of aerobic energy4 for a global cross-section of the biodiversity of marine animals. [...]."

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Source: Science Direct
Authors: Maocai Shen et al.
DOI: 10.1016/j.marpolbul.2019.110712

Abstract

"Global climate change has attracted worldwide attention. The ocean is the largest active carbon pool on the planet and plays an important role in global climate change. However, marine plastic pollution is getting increasingly serious due to the large consumption and mismanagement of global plastics. The impact of marine plastics on ecosystem responsible for the gas exchange and circulation of marine CO2 may cause more greenhouse gas emissions. Consequently, in this paper, threats of marine microplastics to ocean carbon sequestration are discussed. [...]."

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Source: Nature 
Authors: David J. Hughes et al.
DOI: 10.1038/s41558-020-0737-9

Abstract

"Global warming and local eutrophication simultaneously lower oxygen (O2) saturation and increase biological O2 demands to cause deoxygenation. Tropical shallow waters, and their coral reefs, are particularly vulnerable to extreme low O2 (hypoxia) events. These events can drive mass mortality of reef biota; however, they currently remain unaccounted for when considering coral reef persistence under local environmental alterations and global climatic change. [...]."

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Source: Annual Reviews
Authors: Hervé Claustre et al.
DOI: 10.1146/annurev-marine-010419-010956

Abstract

"Biogeochemical-Argo (BGC-Argo) is a network of profiling floats carrying sensors that enable observation of as many as six essential biogeochemical and bio-optical variables: oxygen, nitrate, pH, chlorophyll a, suspended particles, and downwelling irradiance. This sensor network represents today's most promising strategy for collecting temporally and vertically resolved observations of biogeochemical properties throughout the ocean. All data are freely available within 24 hours of transmission. [...]."

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Source: Nature 
Authors: Romain Guilbaud et al.
DOI: 10.1038/s41561-020-0548-7

Abstract

"The redox chemistry of anoxic continental margin settings evolved from widespread sulfide-containing (euxinic) conditions to a global ferruginous (iron-containing) state in the early Neoproterozoic era (from ~1 to 0.8 billion years ago). Ocean redox chemistry exerts a strong control on the biogeochemical cycling of phosphorus, a limiting nutrient, and hence on primary production, but the response of the phosphorus cycle to this major ocean redox transition has not been investigated. [...]."

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Source: Science Direct
Authors: Antonia Chiarore et al.
DOI: 10.1016/j.marenvres.2020.104967

Abstract

"In marinas and harbours, the accumulation of pollutants in sediments, combined with poor exchange of water with the open sea, poses a major environmental threat. The presence of photosynthetic organisms and the related oxygen production, however, may alleviate the negative effects of environmental contamination on heterotrophic organisms, enhancing their physiological defences. [...]."

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Source: PNAS
Authors: Allison R. Moreno et al.
DOI: 10.1073/pnas.2004986117

Abstract

"Climate-driven depletion of ocean oxygen strongly impacts the global cycles of carbon and nutrients as well as the survival of many animal species. One of the main uncertainties in predicting changes to marine oxygen levels is the regulation of the biological respiration demand associated with the biological pump. Derived from the Redfield ratio, the molar ratio of oxygen to organic carbon consumed during respiration (i.e., the respiration quotient, r −O2:C  r−O2:C ) is consistently assumed constant but rarely, if ever, measured. [...]."

Read the full article here.

Source: Nature 
Authors: Marcos Fontela et al.
DOI: 10.1038/s41598-020-71793-2

Abstract

"The oceanic uptake of atmospheric carbon dioxide (CO2) emitted by human activities alters the seawater carbonate system. Here, the chemical status of the Northeast Atlantic is examined by means of a high-quality database of carbon variables based on the GO-SHIP A25 section (1997–2018). The increase of atmospheric CO2 leads to an increase in ocean anthropogenic carbon (Cant) and a decrease in carbonate that is unequivocal in the upper and mid-layers (0–2,500 m depth). [...]."

Read the full article here.

Source: Wiley Online Library
Authors: T. L. Frölicher et al.
DOI: 10.1029/2020GB006601

Abstract

"It is well established that the ocean is currently losing dissolved oxygen (O2) in response to ocean warming, but the long‐term, equilibrium response of O2 to a warmer climate is neither well quantified nor understood. Here we use idealized multimillennial global warming simulations with a comprehensive Earth system model to show that the equilibrium response in ocean O2 differs fundamentally from the ongoing transient response. [...]."

Read the full article here.

Source: Wiley Online Library
Authors: Ellias Yuming Feng et al.
DOI: 10.1029/2020GL088263

Abstract

"Ocean deoxygenation is a threat to marine ecosystems. We evaluated the potential of two ocean intervention technologies, that is, “artificial downwelling (AD)” and “artificial upwelling (AU),” for remedying the expansion of Oxygen Deficient Zones (ODZs). The model‐based assessment simulated AD and AU implementations for 80 years along the eastern Pacific ODZ. [...]."

Read the full article here.

Source: Wiley Online Library
Authors: Raghab Ray et al.
DOI: 10.1029/2020JG005739

Abstract

"There is growing evidence that a substantial fraction of the dissolved organic and inorganic carbon (DOC and DIC) and particulate organic carbon (POC) can be exported from mangroves to the ocean. Yet our understanding of C fluxes in mangrove forests is limited to only few regional studies that exclude the world's longest sediment dispersal system connected to the Amazon River. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Stacy Deppeler et al.
DOI: 10.5194/bg-17-4153-2020

Abstract

"High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic CO2 emissions continue. Marine microbes are an essential part of the marine food web and are a critical link in biogeochemical processes in the ocean, such as the cycling of nutrients and carbon. Despite this, the response of Antarctic marine microbial communities to ocean acidification is poorly understood. We investigated the effect of increasing fCO2 on the growth of heterotrophic nanoflagellates (HNFs), nano- and picophytoplankton, and prokaryotes (heterotrophic Bacteria and Archaea) in a natural coastal Antarctic marine microbial community from Prydz Bay, East Antarctica. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Christopher Gordon et al.
DOI: 10.5194/bg-17-41110.5194

Abstract

"Oceanic primary production forms the basis of the marine food web and provides a pathway for carbon sequestration. Despite its importance, spatial and temporal variations of primary production are poorly observed, in large part because the traditional measurement techniques are laborious and require the presence of a ship. More efficient methods are emerging that take advantage of miniaturized sensors integrated into autonomous platforms such as gliders and profiling floats. One such method relies on determining the diurnal cycle of dissolved oxygen in the mixed layer and has been applied successfully to measurements from gliders and mixed-layer floats. [...].”

Read the full article here.

"NOAA and its partners will report on their recent research cruise to measure the extent of the hypoxic or “dead zone” in the Gulf of Mexico during a media teleconference on Tue., Aug. 4 at 11:00 a.m. EDT.

In June, NOAA scientists forecasted this summer’s dead zone – an area of low to no oxygen that can kill fish and other marine life – to be approximately 6,700 square miles. That is larger than the long-term average measured size of 5,387 square miles, but substantially less than the record of 8,776 square miles set in 2017."

Visit the announcement here.

Source: Frontiers in Marine Science
Authors: Luis Medina Faull et al.
DOI: 10.3389/fmars.2020.00360

Abstract

"The Eastern Tropical North Pacific (ETNP) is a large, persistent, and intensifying oxygen minimum zone (OMZ) that accounts for almost half of the total area of global OMZs. Within the OMZ core (∼350–700 m depth), dissolved oxygen is typically near or below the analytical detection limit of modern sensors (∼10 nM). Steep oxygen gradients above and below the OMZ core lead to vertical structuring of microbial communities that also vary between particle-associated (PA) and free-living (FL) size fractions. [...]."

Read the full article here.

Source: Nature 
Authors: Fei Chai et al.
DOI: 10.1038/s43017-020-0053-y

Abstract

"Human activities have altered the state of the ocean, leading to warming, acidification and deoxygenation. These changes impact ocean biogeochemistry and influence ecosystem functions and ocean health. The long-term global effects of these changes are difficult to predict using current satellite sensing and traditional in situ observation techniques. [...]."

Read the full article here.

Source: Nature
Authors: Zhen-Zhen Zheng et al.
DOI: 10.1038/s41467-020-17366-3

Abstract

"In the context of continuously increasing anthropogenic nitrogen inputs, knowledge of how ammonia oxidation (AO) in the ocean responds to warming is crucial to predicting future changes in marine nitrogen biogeochemistry. Here, we show divergent thermal response patterns for marine AO across a wide onshore/offshore trophic gradient. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Jin-Yu Terence Yang et al.
DOI: 10.5194/bg-17-3631-2020

Abstract

"Temporal variations in excess nitrate (DIN_xs) relative to dissolved inorganic phosphorus (DIP) were evaluated using datasets derived from repeated measurements along meridional and zonal transects in the upper (200–600 m) North Atlantic (NAtl) between the 1980s and 2010s. The analysis revealed that the DIN_xs trend in the western NAtl differed from that in the eastern NAtl. In the western NAtl, which has been subject to atmospheric nitrogen deposition (AND) from the USA, the subsurface DIN_xs concentrations have increased over the last 2 decades. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Yuri Galletti et al.
DOI: 10.5194/bg-17-3669-2020

Abstract

"Atmospheric fluxes of dissolved organic matter (DOM) were studied for the first time on the island of Lampedusa, a remote site in the central Mediterranean Sea (Med Sea), between 19 March 2015 and 1 April 2017. The main goals of this study were to quantify total atmospheric deposition of DOM in this area and to evaluate the impact of Saharan dust deposition on DOM dynamics in the surface waters of the Mediterranean Sea. Our data show high variability in DOM deposition rates without a clear seasonality and a dissolved organic carbon (DOC) input from the atmosphere of 120.7 mmol DOC m⁻² yr⁻¹. [...]."

Read the full article here.

Source: Nature
Authors: Jens Terhaar et al.
DOI: 10.1038/s41586-020-2360-3

Abstract

"The ongoing uptake of anthropogenic carbon by the ocean leads to ocean acidification, a process that results in a reduction in pH and in the saturation state of biogenic calcium carbonate minerals aragonite (Ω_arag) and calcite (Ω_calc). Because of its naturally low Ω_arag and Ω_calc (refs.), the Arctic Ocean is considered the region most susceptible to future acidification and associated ecosystem impacts. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Lester Kwiatkowski et al.
DOI: 10.5194/bg-17-3439-2020

Abstract

"Anthropogenic climate change is projected to lead to ocean warming, acidification, deoxygenation, reductions in near-surface nutrients, and changes to primary production, all of which are expected to affect marine ecosystems. Here we assess projections of these drivers of environmental change over the twenty-first century from Earth system models (ESMs) participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) that were forced under the CMIP6 Shared Socioeconomic Pathways (SSPs). [...]."

Read the full article here.

Source: Biogeosciences
Authors: Andrew H. MacDougall et al.
DOI: 10.5194/bg-17-2987-2020

Abstract

"The Zero Emissions Commitment (ZEC) is the change in global mean temperature expected to occur following the cessation of net CO₂ emissions and as such is a critical parameter for calculating the remaining carbon budget. The Zero Emissions Commitment Model Intercomparison Project (ZECMIP) was established to gain a better understanding of the potential magnitude and sign of ZEC, in addition to the processes that underlie this metric. [...]."

Read the full article here.

"A Story of the Collaborative Research Centre "Climate-Biogeochemistry Interactions in the Tropical Ocean"

After 12 years of intensive research, the Collaborative Research Centre 754 "Climate-Biogeochemical Interactions in the Tropical Ocean" ended in winter 2019 with a final symposium in Heiligenhafen.

More than 100 scientists involved in the large-scale project over its entire running time were able to gain numerous new insights into the processes of nutrient cycling, the interaction between ocean and atmosphere and the ecosystems in the tropical oceans. Above all, however, they drew attention to a phenomenon that affects the entire ocean: global oxygen loss and the spread of oxygen minimum zones in the ocean. With this video, the SFB 754 now draws a conclusion and at the same time points out the new research tasks that have resulted from its work. These include improved ocean observation and the question of how to prevent further oxygen loss.

For more information, please look at www.sfb754.de."

For a German version of the video, please follow this link.

Source: Wiley Online Library
Authors: Alexandra Steckbauer et al.
DOI: 10.1111/gcb.15252

Abstract

"Deoxygenation in coastal and open‐ocean ecosystems rarely exists in isolation but occurs concomitantly with acidification. Here, we first combine meta‐data of experimental assessments from across the globe to investigate the potential interactive impacts of deoxygenation and acidification on a broad range of marine taxa. [...]."

Read the full article here.

Source: Phys.org

"A type of anaerobic bacteria responsible for more than 50 percent of nitrogen loss from marine environments has been shown to use solid-state matter present outside their cells for respiration. The finding by KAUST researchers adds to knowledge of the global nitrogen cycle and has important energy-saving potential for wastewater treatment. [...]."

Read the full article here.

Source: One Earth
Authors: Andrea Franke et al.
DOI: 10.1016/j.oneear.2020.05.013

Abstract

"Protecting the ocean has become a major goal of international policy as human activities increasingly endanger the integrity of the ocean ecosystem, often summarized as ‘‘ocean health.’’ By and large, efforts to protect the ocean have failed because, among other things, (1) the underlying socio-ecological pathways have not been properly considered, and (2) the concept of ocean health has been ill defined. Collectively, this prevents an adequate societal response as to how ocean ecosystems and their vital functions for human societies can be protected and restored. We review the confusion surrounding the term ‘‘ocean health’’ and suggest an operational ocean-health framework in line with the concept of strong sustainability. [...]."

Read the full article here.

Source: University of Michigan

"Researchers from the University of Michigan, the Chesapeake Bay Program and the University of Maryland Center for Environmental Science are forecasting a slightly smaller-than-average Chesapeake Bay “dead zone” this year, due to reduced rainfall and less nutrient-rich runoff flowing into the bay from the watershed this spring. [...]."

Read the full article here.

Source: NOAA

"NOAA scientists are forecasting this summer’s Gulf of Mexico hypoxic area or “dead zone” – an area of low to no oxygen that can kill fish and other marine life – to be approximately 6,700 square miles, larger than the long-term average measured size of 5,387 square miles but substantially less than the record of 8,776 square miles set in 2017. The annual prediction is based on U.S. Geological Survey river-flow and nutrient data. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Alexander Bratek et al.
DOI: 10.5194/bg-17-2839-2020

Abstract

"In this study, we investigate the role of sedimentary N cycling in the southern North Sea. We present a budget of ammonification, nitrification and sedimentary NO−3 consumption and denitrification in contrasting sediment types of the German Bight (southern North Sea), including novel net ammonification rates. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Fabian Große et al.
DOI: 10.5194/bg-17-2701-2020

Abstract

"In the East China Sea, hypoxia (oxygen ≤ 62.5 mmol m⁻³) is frequently observed off the Changjiang (or Yangtze River) estuary covering up to about 15 000 km². The Changjiang is a major contributor to hypoxia formation because it discharges large amounts of freshwater and nutrients into the region. However, modeling and observational studies have suggested that intrusions of nutrient-rich oceanic water from the Kuroshio Current also contribute to hypoxia formation. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Jérôme Kaiser et al.
DOI: 10.5194/bg-17-2579-2020

Abstract

"Summer cyanobacterial blooms represent a threat to the Baltic Sea ecosystem, causing deoxygenation of the bottom water and the spread of the so-called dead zones. The history of the Baltic Sea cyanobacterial blooms is known from in situ and satellite observations since the early 1980s but is still not well understood. [...]."

Read the full article here.

Source: Chesapeake Bay Program 
Author: Kaitlyn May 

"An estimated 38% of the Chesapeake Bay and its tidal tributaries met clean water standards for clarity, oxygen and algae growth between 2016 and 2018. This score is lower than the record high 42% from the previous reporting period, but is still the fifth highest estimate of water quality standards attainment since 1985. This four percentage point decrease is due in large part to a decline in dissolved oxygen in the open waters of the Bay, those areas beyond the shoreline and shallows. Dissolved oxygen is necessary for the survival of the Bay’s aquatic species, and is a factor in the annual dead zone. [...]."

Read the full article here.

Source: Science
Authors: Jonathan P. Zehr & Douglas G. Capone
DOI: 10.1126/science.aay9514

Abstract

"Biological dinitrogen (N₂) fixation, the reduction of atmospheric N₂ to ammonia, is important for maintaining the fertility of the oceans by providing biologically useful nitrogen to support primary organic matter production (i.e., carbon dioxide fixation). N₂ fixation offsets the removal of combined nitrogen by microbial denitrification and anaerobic ammonium oxidation (anammox) and export to the deep sea. For several decades, there has been a lack of consensus as to whether losses of N through microbial removal pathways are balanced by biological nitrogen fixation, along with other inputs such as atmospheric nitrogen deposition and terrestrial runoff. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Carolin R. Löscher et al.
DOI: 10.5194/bg-17-851-2020

Abstract

"The Bay of Bengal (BoB) has long stood as a biogeochemical enigma, with subsurface waters containing extremely low, but persistent, concentrations of oxygen in the nanomolar range which – for some, yet unconstrained, reason – are prevented from becoming anoxic. One reason for this may be the low productivity of the BoB waters due to nutrient limitation and the resulting lack of respiration of organic material at intermediate waters. [...]."

Read the full article here.

Source: EOS
Author: Jon Kelvey

"Every year, the Mississippi River dumps around 1.4 million metric tons of nitrogen into the Gulf of Mexico, much of it runoff from agricultural fertilizer. This nitrogen can lead to algal blooms, which in turn deplete oxygen concentrations in the water, creating hypoxic dead zones. The nitrogen cycle is a phenomenon environmental scientists would really like to understand better. “As humans, we do put a lot of reactive nitrogen compounds into the ocean, especially in coastal regions, by…river runoff,” said Katharina Kitzinger of the Max Planck Institute for Marine Microbiology in Bremen, Germany. “It’s really crucial to understand how microbes turn over this excess nitrogen that we put into the environment.” [...]."

Read the full article here.

Source: Biogeosciences
Auhtors: Kenta Watanabe et al.
DOI: 10.5194/bg-17-2425-2020

Abstract

"Macroalgal beds have drawn attention as one of the vegetated coastal ecosystems that act as atmospheric CO₂ sinks. Although macroalgal metabolism as well as inorganic and organic carbon flows are important pathways for CO₂ uptake by macroalgal beds, the relationships between macroalgal metabolism and associated carbon flows are still poorly understood. In the present study, we investigated carbon flows, including air–water CO₂ exchange and budgets of dissolved inorganic carbon, total alkalinity, and dissolved organic carbon (DOC), in a temperate macroalgal bed during the productive months of the year. [...]."

Read the full articele here.

Source: Nature 
Authors: Mak A. Saito et al.
DOI: 10.1038/s41561-020-0565-6

Abstract

"Numerous biogeochemical reactions occur within the oceans’ major oxygen minimum zones, but less attention has been paid to the open ocean extremities of these zones. Here we report measurements on oxygen minimum zone waters from the Eastern to the Central Tropical North Pacific, which we analysed using metaproteomic techniques to discern the microbial functions present and their influence on biogeochemical cycling. [...]."

Read the full article here.

Source: Climate of the Past
Authors: Sebastian Beil et al.
DOI: 10.5194/cp-16-757-2020

Abstract

"Oceanic anoxic events (OAEs) document major perturbations of the global carbon cycle with repercussions for the Earth's climate and ocean circulation that are relevant to understanding future climate trends. Here, we compare the onset and development of Cretaceous OAE1a and OAE2 in two drill cores with unusually high sedimentation rates from the Vocontian Basin (southern France) and Tarfaya Basin (southern Morocco). OAE1a and OAE2 exhibit remarkable similarities in the evolution of their carbon isotope (δ¹³C) records, with long-lasting negative excursions preceding the onset of the main positive excursions, supporting the view that both OAEs were triggered by massive emissions of volcanic CO₂ into the atmosphere. However, there are substantial differences, notably in the durations of individual phases within the δ¹³C positive excursions of both OAEs. [...]."

Read the full article here.

Source: Science Direct
Authors: Fernando Núñez-Useche et al.
DOI: 10.1016/j.cretres.2020.104488

Abstract

"Integrated microfacies and geochemical analyses conducted on five stratigraphic sections in northeastern Mexico (ancentral western margin of the proto-North Atlantic) reveal major paleoenvironmental changes in shallow water and pelagic environments in the prelude and run-up of the early Aptian oceanic anoxic event (OAE) 1a. During the Barremian–Aptian transition, the replacement of photozoan rudist-coral by mesotrophic/eutrophic orbitolinid-miliolid communities in the Cupido platform occurred in association with increased nutrient input. [...]."

Read the full article here.

Source: Science Direct
Authors: Stefano Bonaglia et al.
DOI: 10.1016/j.marenvres.2020.104968

Abstract

"Oxygen depleted areas are widespread in the marine realm. Unlike macrofauna, meiofauna are abundant in hypoxic sediments. We studied to what extent meiofauna affect oxygen availability, sulfide removal and microbial communities. Meiofauna were extracted alive and added to intact sediments simulating abundance gradients previously reported in the area. [...]."

Read the full article here.

Source: Biogeosciences
Authors: Claudia Frey et al.
DOI: 10.5194/bg-17-2263-2020

Abstract

"Oxygen-deficient zones (ODZs) are major sites of net natural nitrous oxide (N₂O) production and emissions. In order to understand changes in the magnitude of N₂O production in response to global change, knowledge on the individual contributions of the major microbial pathways (nitrification and denitrification) to N₂O production and their regulation is needed. In the ODZ in the coastal area off Peru, the sensitivity of N₂O production to oxygen and organic matter was investigated using ¹⁵N tracer experiments in combination with quantitative PCR (qPCR) and microarray analysis of total and active functional genes targeting archaeal amoA and nirS as marker genes for nitrification and denitrification, respectively. [...]."

Read the full article here.

Source: Science
Authors: Stephen J. Tomasetti & Christopher J. Gobler
DOI: 10.1126/science.aba4896

Abstract

"Changes in human population centers and agricultural fertilizer use have accelerated delivery rates of nitrogen and phosphorus to coastal waters, often stimulating rapid accumulations of primary production (1). Whereas resulting eutrophication processes are of less environmental relevance in well-mixed, ocean ecosystems, when they occur in warm, stratified, and/or poorly mixed waters, they can result in hypoxia [depletion of dissolved oxygen (DO)] and acidification (decrease in pH), both of which individually can have adverse effects on aquatic life, affecting a suite of physiological processes and increasing mortality rates (2, 3). [...]."

Read the full article here.

Source: Springer Link 
Authors: B. Sridevi & V.V.S.S. Sarma
DOI: 10.1007/s12040-020-1376-2

Abstract

"Occurrence of intense oxygen minimum zone (OMZ) is known in the Bay of Bengal (BoB), but it has been recently reported to have become more acute and is at its tipping point. Here, we show that the intensification of OMZ to acute condition is a random and short-term rather than perennial phenomenon based on re-evaluation of old and recent information in the BoB. Short-term modifications in dissolved oxygen (DO) in the OMZ are caused by balance among physical forcings: salinity stratification, occurrence of cyclonic (CE), and anticyclonic eddies (ACE). [...]."

Read the full article here.

Source: Mongabay
Author: Elizabeth Claire Alberts

"In March, Australia’s Great Barrier Reef suffered its most widespread bleaching event to date. Sixty percent of the reef underwent moderate to severe bleaching, and some corals may never recover. The cause of this bleaching event was climate change, which brought unusually warm waters to the Great Barrier Reef in February, and disrupted the delicate, symbiotic relationship between the corals and their life-sustaining algae. In general, when sea temperatures rise, corals become stressed and expel algae from their tissues. Without this algae, the corals turn ghostly white and slowly starve. [...]."

Read the full article here.

Source: Nature 
Auhtors: C. V. Ullmann et al.
DOI: 10.1038/s41598-020-63487-6

Abstract

"Many aspects of the supposed hyperthermal Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic, c. 182 Ma) are well understood but a lack of robust palaeotemperature data severely limits reconstruction of the processes that drove the T-OAE and associated environmental and biotic changes. New oxygen isotope data from calcite shells of the benthic fauna suggest that bottom water temperatures in the western Tethys were elevated by c. 3.5 °C through the entire T-OAE. [...]."

Read the full article here.

Source: Ocean Science
Authors: Claudia Wekerle et al.
DOI: 10.5194/os-16-1225-2020

Abstract

"Fram Strait, the deepest gateway to the Arctic Ocean, is strongly influenced by eddy dynamics. Here we analyse the output from two eddy-resolving models (ROMS – Regional Ocean Modeling System; FESOM – Finite-Element Sea-ice Ocean Model) with around 1 km mesh resolution in Fram Strait, with a focus on their representation of eddy properties and dynamics. A comparison with mooring observations shows that both models reasonably simulate hydrography and eddy kinetic energy. [...]."

Read the full article here.

Source: Phys.org
Author: Danielle Torrent Tucker

"In a new study, Stanford researchers have strongly bolstered the theory that a lack of oxygen in Earth's oceans contributed to a devastating die-off approximately 444 million years ago. The new results further indicate that these anoxic (little- to no-oxygen) conditions lasted over 3 million years—significantly longer than similar biodiversity-crushing spells in our planet's history. Beyond deepening understandings of ancient mass extinction events, the findings have relevance for today: Global climate change is contributing to declining oxygen levels in the open ocean and coastal waters, a process that likely spells doom for a variety of species. [...]."

Read the full article here.

Source: Science Direct
Authors: Daniel L. Sullivan et al.
DOI: 10.1016/j.gca.2020.04.002

Abstract

"Oceanic anoxic Event 2 (OAE-2) occurred at the Cenomanian-Turonian boundary (∼94.1 Ma) and was a time of profound global changes in ocean chemistry and the carbon cycle. This event was characterized by a positive carbon isotope excursion (CIE) caused by massive organic carbon burial, global greenhouse temperatures, ocean deoxygenation, and changes in ocean life driven by large igneous province (LIP) activity. LIPS throughout the Phanerozoic have had dynamic magma flux, with episodes of major eruptions interspersed with periods of relatively less intense eruptions. [...]."

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Source: Biogeosciences
Authors: Angélique Hameau et al.
DOI: 10.5194/bg-17-1877-2020

Abstract

"Anthropogenic greenhouse gas emissions cause ocean warming and oxygen depletion, with adverse impacts on marine organisms and ecosystems. Warming is one of the main indicators of anthropogenic climate change, but, in the thermocline, changes in oxygen and other biogeochemical tracers may emerge from the bounds of natural variability prior to warming. Here, we assess the time of emergence (ToE) of anthropogenic change in thermocline temperature and thermocline oxygen within an ensemble of Earth system model simulations from the fifth phase of the Coupled Model Intercomparison Project. [...]."

Read the full article here.

Source: Wiley Online Library
Authors: Tyler Rohr et al.
DOI: 10.1029/2019GB006385

Abstract

"We examine the structure and drivers of anomalous phytoplankton biomass in Southern Ocean eddies tracked in a global, multi‐year, eddy‐resolving, 3‐D ocean simulation of the Community Earth System Model. We examine how simulated anticyclones and cyclones differentially modify phytoplankton biomass concentrations, growth rates, and physical transport. [...]."

Read the full article here.

Source: Nature 
Authors: Ruimin Wang et al.
DOI: 10.1038/s41598-020-62816-z

Abstract

"Organic matter production and decomposition primarily modulate the atmospheric O₂ and CO₂ levels. The long term marine primary productivity is controlled by the terrestrial input of phosphorus (P), while the marine P cycle would also affect organic matter production. In the past 540 million years, the evolution of terrestrial system, e.g. colonization of continents by vascular land plants in late Paleozoic, would certainly affect terrestrial P input into the ocean, which in turn might have impacted the marine primary productivity and organic carbon burial. [...]."

Read the full article here.

Source: Nature 
Authors: David J. Hughes et al.
DOI: 10.1038/s41558-020-0737-9

Abstract

"Global warming and local eutrophication simultaneously lower oxygen (O₂) saturation and increase biological O₂ demands to cause deoxygenation. Tropical shallow waters, and their coral reefs, are particularly vulnerable to extreme low O₂ (hypoxia) events. These events can drive mass mortality of reef biota; however, they currently remain unaccounted for when considering coral reef persistence under local environmental alterations and global climatic change. [...]."

Read the full article here.

Source: GeoScienceWorld
Authors: Johanna Marin Carbonne
DOI: 10.1130/focus042020.1

Abstract

"In the history of this continuously evolving planet, the Great Oxygenation Event (GOE), which occurred at ca. 2.3 Ga (Bekker et al., 2004; Holland, 2006) was a critical environmental change. This event was first recognized by the disappearance of detrital uraninite, pyrite, and siderite, from the siliciclastic record, as well as by shales that do not contain appreciable amounts of redox-sensitive elements and paleosols that are not oxidized before ca. 2.3 Ga (Holland, 2006). [...]."

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Source: Nature 
Authors: Melissa M. Omand et al.
DOI: 10.1038/s41598-020-60424-5

Abstract

"The sinking of organic particles produced in the upper sunlit layers of the ocean forms an important limb of the oceanic biological pump, which impacts the sequestration of carbon and resupply of nutrients in the mesopelagic ocean. Particles raining out from the upper ocean undergo remineralization by bacteria colonized on their surface and interior, leading to an attenuation in the sinking flux of organic matter with depth. [...]."

Read the full article here.

Source: Nature
Authors: D. Atamanchuk et al.
DOI: 10.1038/s41561-020-0532-2

Abstract

"The concentration of oxygen exerts major controls on life in the ocean, and its distribution in the ocean and atmosphere carries information about biological productivity, transports of mass and heat, ocean deoxygenation and global carbon sinks. Our understanding of processes underlying oxygen distributions, their key features and variability is often lacking. [...]."

Read the full article here.

Source: Science Direct
Authors: Wei Li et al.
DOI: 10.1016/j.marenvres.2020.104965

Abstract

"Phytoplankton in the upper oceans are exposed to changing light levels due to mixing, diurnal solar cycles and weather conditions. Consequently, effects of ocean acidification are superimposed upon responses to variable light levels. We therefore grew a model diatom Thalassiosira pseudonana under either constant or variable light but at the same daily photon dose, with current low (400 μatm, LC) and future high CO₂ (1000 μatm, HC) treatments. [...]."

Read the full article here.

Source: Nature
Authors: Crystal A. Ng & Fiorenza Micheli 
DOI: 10.1038/s41598-020-62294-3

Abstract

"Species interactions are crucial for the persistence of ecosystems. Within vegetated habitats, early life stages of plants and algae must survive factors such as grazing to recover from disturbances. However, grazing impacts on early stages, especially under the context of a rapidly changing climate, are largely unknown. [...]."

Read the full article here.

Source: Wiley Online Library
Authors: Paula Ruiz‐Fernández et al.
DOI: 10.1111/1758-2229.12837

Abstract

"Anoxic marine zones (AMZs), also known as ‘oxygen‐deficient zones’, contribute to the loss of fixed nitrogen from the ocean by anaerobic microbial processes. While these microbial processes associated with the nitrogen cycle have been extensively studied, those linked to the carbon cycle in AMZs have received much less attention, particularly the autotrophic carbon fixation —a crucial component of the carbon cycle. [...]."

Read the full article here.

Source: Nature 
Authors: Ehui Tan et al.
DOI: 10.1038/s41558-020-0723-2

Abstract

"Temperature is one of the fundamental environmental variables governing microbially mediated denitrification and anaerobic ammonium oxidation (anammox) in sediments. The GHG nitrous oxide (N₂O) is produced during denitrification, but not by anammox, and knowledge of how these pathways respond to global warming remains limited. [...]."

Read the full article here.

Source: The University of Hong Kong

"A new research led by MPhil student Miss Yu Yan Yau and supervised by Dr Benoit Thibodeau from the Department of Earth Sciences and the Swire Institute of Marine Science, the University of Hong Kong (HKU), highlighted the importance of reducing fossil fuel combustion not only to curb the trend of global warming, but also to improve the quality of China’s coastal waters. The findings were recently published in the prestigious journal Environmental Science & Technology. [...]."

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Source: Global Research
Author: Robert J. Burrowes

"As the human onslaught against life on Earth accelerates, no part of the biosphere is left pristine. The simple act of consuming more than we actually need drives the world’s governments and corporations to endlessly destroy more and more of the Earth to extract the resources necessary to satisfy our insatiable desires. In fact, an initiative of the World Economic Forum has just reported that ‘For the first time in history, more than 100 billion tonnes of materials are entering the global economy every year’ – see ‘The Circularity Gap Report 2020’– which means that, on average, every person on Earth uses more than 13 tonnes of materials each year extracted from the Earth. [...]."

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Source: Science Daily

"Thanks to a new algorithm, researchers can now use satellite data to determine in which parts of the ocean certain types of phytoplankton are dominant. In addition, they can identify toxic algal blooms and assess the effects of global warming on marine plankton, allowing them to draw conclusions regarding water quality and the ramifications for the fishing industry. [...]."

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Source: Wiley Online Library
Authors: Devon B. Cole et al.
DOI: 10.1111/gbi.12382

Abstract

"Few topics in geobiology have been as extensively debated as the role of Earth's oxygenation in controlling when and why animals emerged and diversified. All currently described animals require oxygen for at least a portion of their life cycle. Therefore, the transition to an oxygenated planet was a prerequisite for the emergence of animals. Yet, our understanding of Earth's oxygenation and the environmental requirements of animal habitability and ecological success is currently limited; estimates for the timing of the appearance of environments sufficiently oxygenated to support ecologically stable populations of animals span a wide range, from billions of years to only a few million years before animals appear in the fossil record. [...]."

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Source: Wiley Online Library
Authors: Kathryn I. Rico et al. 
DOI: 10.1111/gbi.12388

Abstract

"Constraints on Precambrian ocean chemistry are dependent upon sediment geochemistry. However, diagenesis and metamorphism can destroy primary biosignatures, making it difficult to consider biology when interpreting geochemical data. Modern analogues for ancient ecosystems can be useful tools for identifying how sediment geochemistry records an active biosphere. The Middle Island Sinkhole (MIS) in Lake Huron is an analogue for shallow Proterozoic waters due to its low oxygen water chemistry and microbial communities that exhibit diverse metabolic functions at the sediment–water interface. [...]."

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Source: Nature
Authors: Veronica Piazza et al.
DOI: 10.1038/s41598-020-61393-5

Abstract

"The Toarcian Oceanic Anoxic Event (TOAE, Early Jurassic, ~182 Ma ago) was characterised by severe environmental perturbations which led to habitat degradation and extinction of marine species. Warming-induced anoxia is usually identified as main driver, but because marine life was also affected in oxygenated environments the role of raised temperature and its effects on marine life need to be addressed. [...]."

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Source: The Guardian
Author: Damian Carrington

"First seagrass restoration in Britain will capture carbon rapidly and offer habitat for lost marine life.
“We think this whole bay was once carpeted with seagrass,” says Evie Furness, waving across the sparkling, sunlit waters of Dale Bay in Pembrokeshire, Wales. The underwater meadow is long gone though, a victim of past pollution and shipping. So from a boat half a mile from shore, Furness is feeding a long rope into the water, which carries a little hessian bag of seagrass seeds every metre. “We’ve passed the 800,000 seed mark now,” she says. [...]."

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Source: Wiley Online Library
Authors: Evan G. Mattiasen et al.
DOI: 10.1111/gcb.15076

Abstract

"Forecasts from climate models and oceanographic observations indicate increasing deoxygenation in the global oceans and an elevated frequency and intensity of hypoxic events in the coastal zone, which have the potential to affect marine biodiversity and fisheries. Exposure to low dissolved oxygen (DO) conditions may have deleterious effects on early life stages in fishes. [...]."

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Source: Geoscientific Model Development
Authors: Christopher T. Reinhard et al.
DOI: 10.5194/gmd-13-5687-2020

Abstract

"The methane (CH₄) cycle is a key component of the Earth system that links planetary climate, biological metabolism, and the global biogeochemical cycles of carbon, oxygen, sulfur, and hydrogen. However, currently lacking is a numerical model capable of simulating a diversity of environments in the ocean where CH4 can be produced and destroyed, and with the flexibility to be able to explore not only relatively recent perturbations to Earth’s CH₄ cycle but also to probe CH₄ cycling and associated climate impacts under the very low-O2 conditions characteristic of most of Earth history and likely widespread on other Earth-like planets. [...]."

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Source: Nature 
Authors: Elias Broman et al.
DOI: 10.1038/s42003-020-0822-7

Abstract

"Ocean deoxygenation driven by global warming and eutrophication is a primary concern for marine life. Resistant animals may be present in dead zone sediments, however there is lack of information on their diversity and metabolism. Here we combined geochemistry, microscopy, and RNA-seq for estimating taxonomy and functionality of micrometazoans along an oxygen gradient in the largest dead zone in the world. [...]."

Read the full article here.

Source: Popular Science
Author: Kate Baggaley

"The fish that live at the bottom of the sea are a hardy bunch. They’re adapted to handle crushing pressure, little to no sunlight, and a meager supply of food. But these otherwise gritty fish are also very sensitive to changes in the climate of the water around them, a new study suggests.

Scientists surveyed different patches of seafloor in the Gulf of California and saw that variations in temperature and oxygen levels had a huge impact on whether the fish community was thriving or sparse. In particular, the researchers found that one specific combination—warmer waters mixed with low oxygen levels—didn’t bode well for deep sea fish. This means that these creatures are likely to be vulnerable to the impacts of climate change, the researchers reported March 5 in Marine Ecology Progress Series. [...]."

Read the full article here.

Source: Science
Author: Erik Stokstad
DOI: 10.1126/science.abb5645

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

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Source: Science Daily 

"Could pumping oxygen-rich surface water into the depths of lakes, estuaries, and coastal ocean waters help ameliorate dangerous dead zones? New work says yes, although they caution that further research would be needed to understand any possible side effects before implementing such an approach. [...]."

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Source: Nature
Authors: Romain Guilbaud et al.
DOI: 10.1038/s41561-020-0548-7

Abstract

"The redox chemistry of anoxic continental margin settings evolved from widespread sulfide-containing (euxinic) conditions to a global ferruginous (iron-containing) state in the early Neoproterozoic era (from ~1 to 0.8 billion years ago). Ocean redox chemistry exerts a strong control on the biogeochemical cycling of phosphorus, a limiting nutrient, and hence on primary production, but the response of the phosphorus cycle to this major ocean redox transition has not been investigated. [...]."

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Source: Science Direct
Authors: Wanyi Lu et al.
DOI: 10.1016/j.epsl.2019.116055

Abstract

"The decline in dissolved oxygen in global oceans (ocean deoxygenation) is a potential consequence of global warming which may have important impacts on ocean biogeochemistry and marine ecosystems. Current climate models do not agree on the trajectory of future deoxygenation on different timescales, in part due to uncertainties in the complex, linked effects of changes in ocean circulation, productivity and organic matter respiration. [...]."

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Source: Earth System Science Data
Authors: Michio Aoyama
DOI: 10.5194/essd-12-487-2020

Abstract

"A global nutrient gridded dataset that might be the basis for studies of more accurate spatial distributions of nutrients in the global ocean was created and named GND13. During 30 cruises, reference materials of nutrients in seawater or their equivalents were used at all stations, and high-precision measurements were made. The precision of the nutrient analyses was better than 0.2 %. Data were collected from the hydrographic cruises in the JASMTEC R/V Mirai cruises, JMA cruise, CARINA, PACIFICA, and WGHC datasets from which nutrient data were available. [...]."

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Source: Science Direct
Authors: F. Garrett Boudinot et al.
DOI: 10.1016/j.palaeo.2020.109673

Abstract

"Cretaceous oceanic anoxic events (OAEs) were periods of geologically short (<1 million years) global change characterized by elevated temperatures, changes in ocean biogeochemistry, ecological turnover, and the global-scale deposition of black shales. After decades of OAE research, the intensity and spatiotemporal heterogeneity of ocean anoxia and its direct effects on marine ecology remain areas of active study. We present high-resolution organic geochemical and foraminiferal records from the western margin of the Western Interior Seaway (WIS) during the Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE2, ~94 Ma) that indicate reorganization of a neritic ecosystem in response to sea-level rise, and dynamic changes in redox conditions that were likely driven by enhanced marine productivity. [...]."

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Source: Nature 
Authors: Christopher C. Chapman et al.
DOI: 10.1038/s41558-020-0705-4

Abstract

"The Southern Ocean is a critical component of the global climate system and an important ecoregion that contains a diverse range of interdependent flora and fauna. It also hosts numerous fronts: sharp boundaries between waters with different characteristics. As they strongly influence exchanges between the ocean, atmosphere and cryosphere, fronts are of fundamental importance to the climate system. However, rapid advances in physical oceanography over the past 20 years have challenged previous definitions of fronts and their response to anthropogenic climate change. [...]."

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Source: Climate of the Past
Authors: Jianjun Zou et al.
DOI: 10.5194/cp-16-387-2020

Abstract

"The deep-ocean carbon cycle, especially carbon sequestration and outgassing, is one of the mechanisms to explain variations in atmospheric CO₂ concentrations on millennial and orbital timescales. However, the potential role of subtropical North Pacific subsurface waters in modulating atmospheric CO₂ levels on millennial timescales is poorly constrained. An increase in the respired CO₂ concentration in the glacial deep-ocean due to biological pump generally corresponds to deoxygenation in the ocean interior. [...]."

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

Abstract

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

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

Abstract

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

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Source: Science Daily

"A new study suggests that iron fertilization may not have a significant impact on phytoplankton growth, at least on a global scale.
Historically, the oceans have done much of the planet's heavy lifting when it comes to sequestering carbon dioxide from the atmosphere. Microscopic organisms known collectively as phytoplankton, which grow throughout the sunlit surface oceans and absorb carbon dioxide through photosynthesis, are a key player. [...]."

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Source: Biogeosciences
Authors: Lothar Stramma et al.
DOI: 10.5194/bg-17-813-2020

Abstract

"A strong oxygen-deficient layer is located in the upper layers of the tropical Pacific Ocean and deeper in the North Pacific. Processes related to climate change (upper-ocean warming, reduced ventilation) are expected to change ocean oxygen and nutrient inventories. In most ocean basins, a decrease in oxygen (“deoxygenation”) and an increase in nutrients have been observed in subsurface layers. Deoxygenation trends are not linear and there could be multiple influences on oxygen and nutrient trends and variability. [...]."

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Source: Nature 
Authors: Natalie H. N. Low & Fiorenza Micheli 
DOI: 10.1038/s41598-020-59483-5

Abstract

"Climate change is altering the intensity and variability of environmental stress that organisms and ecosystems experience, but effects of changing stress regimes are not well understood. We examined impacts of constant and variable sublethal hypoxia exposures on multiple biological processes in the sea urchin Strongylocentrotus purpuratus, a key grazer in California Current kelp forests, which experience high variability in physical conditions. [...]."

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Source: Springer Link 
Authors: Jun Dai et al.
DOI: 10.1007/s00343-019-9148-z

Abstract

"As in-situ observations are sparse, targeted observations of a specific mesoscale eddy are rare. Therefore, it is difficult to study the three-dimensional structure of moving mesoscale eddies. From April to September 2014, an anticyclonic eddy located at 135°E–155°E, 26°N–42°N was observed using 17 rapid-sampling Argo floats, and the spatiotemporal variations in the three-dimensional structure were studied. [...]."

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

Abstract

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

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Source: Wiley Online Library
Authors: P. Yao et al.
DOI: 10.1029/2019JG005307

Abstract

"Blue holes are unique geomorphological features with steep biogeochemical gradients and distinctive microbial communities. Carbon cycling in blue holes, however, remains poorly understood. Here we describe potential mechanisms of dissolved carbon cycling in the world's deepest blue hole, the Yongle Blue Hole (YBH), which was recently discovered in the South China Sea. In the YBH, we found some of the lowest concentrations (e.g., 22 μM) and oldest ages (e.g., 6,810 years BP) of dissolved organic carbon, as well as the highest concentrations (e.g., 3,090 μM) and the oldest ages (e.g., 8270 years BP) of dissolved inorganic carbon observed in oceanic waters. [...]."

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Source: Nature 
Authors: F. T. Bowyer et al.
DOI: 10.1038/s41598-020-59335-2

Abstract

"The late Ediacaran witnessed an increase in metazoan diversity and ecological complexity, marking the inception of the Cambrian Explosion. To constrain the drivers of this diversification, we combine redox and nutrient data for two shelf transects, with an inventory of biotic diversity and distribution from the Nama Group, Namibia (~550 to ~538 Million years ago; Ma). Unstable marine redox conditions characterised all water depths in inner to outer ramp settings from ~550 to 547 Ma, when the first skeletal metazoans appeared. [...]."

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Source: Wiley Online Library
Authors: Zachary C. Evans et al.
DOI: 10.1002/lno.11412

Abstract

"Oceanic oxygen deficient zones (ODZs) influence global biogeochemical cycles in a variety of ways, most notably by acting as a sink for fixed nitrogen (Codispoti et al. 2001). Optimum multiparameter analysis of data from two cruises in the Eastern Tropical North Pacific (ETNP) was implemented to develop a water mass analysis for the large ODZ in this region. This analysis reveals that the most pronounced oxygen deficient conditions are within the 13°C water (13CW) mass, which is distributed via subsurface mesoscale features such as eddies branching from the California Undercurrent. [...]."

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Source: International Institute for Sustainable Development

"Participants at the 2020 UN Ocean Conference Preparatory Meeting highlighted the importance of a healthy ocean in implementing and achieving the SDGs and stressed that 2020 must be a year of concrete action for the ocean. The 2020 Ocean Conference is one of the first milestones of the UN Secretary-General’s Decade of Action for the SDGs and is expected to provide inputs into the High-level Political Forum on Sustainable Development (HLPF) and the UN Decade of Ocean Science for Sustainable Development. [...]."

Read the full article here.

Source: International Institute for Sustainable Development

"This new decade starts at a critical moment for the future of the Ocean. There is strong agreement among experts that decisions taken in the next ten years will be critical for the future of the Ocean. The current ecological crisis demands a radical shift in the way we treat the marine environment, its precious wildlife, and its invaluable natural resources. We are witnessing continued loss of biodiversity, overfishing, habitat destruction, pollution, and many other serious impacts from human activities – all compounded by climate change, Ocean deoxygenation and acidification. [...]."

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Source: Phys.org
Author: Elaina Hancock

"For the past 25 years, the Environmental Protection Agency and the Connecticut Department of Energy and Environmental Protection have been diligently collecting water samples each month in Long Island Sound (LIS). Recently, the data have been compiled and analyzed, by UConn associate professors of Marine Science Penny Vlahos and Michael Whitney, and other team members, who have begun the task of digging into the data to better understand the biogeochemistry of the Sound. Part of the analysis, called "Nitrogen Budgets for LIS," has been published in the journal Estuarine, Coastal and Shelf Science. [...]."

Read the full article here.

Source: UN News

""Life under water is essential to life on land", said Tijjani Muhammad-Bande. The ocean produces “half of the oxygen we breathe” and provides food for millions of around the world, playing a “fundamental role in mitigating climate change as a major heat and carbon sink”. The Ocean Conference, which will run in Lisbon from 2 to 6 June, aims to propel science-based innovative solutions in the form of global ocean action. The worldwide ocean economy is valued at around $1.5 trillion dollars annually, as aquaculture is the fastest growing food sector and 350 million jobs world-wide are linked to fisheries. [...]."

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Source: Science Direct
Authors: Henry A. Ruhl et al.
DOI: 10.1016/j.dsr2.2020.104741

Abstract

"The biological carbon pump has been estimated to export ∼5–15 Gt C yr⁻¹ into the deep ocean, and forms the principal deep-sea food resource. Irregular, intense pulses of particulate organic carbon (POC) have been found to make up about one-third of the overall POC fluxes at a long-term deep-sea research station influenced by coastal upwelling of the California Current, Station M (34°50′N, 123° W, 4000 m depth). However, the drivers of these pulses have been challenging to quantify. [...]."

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Source: Nature
Authors: L. W. Tait et al.
DOI: 10.1038/s41598-020-58557-8

Abstract

"Predicting the effects of invasive ecosystem engineering species in new bioregions has proved elusive. In part this is because separating biological effects from purely physical mechanisms has been little studied and yet could help predict potentially damaging bioinvasions. Here we tested the effects of a large bio-engineering fanworm Sabella spallanzanii (Sabella) versus worm-like structures (mimics) on gas and nutrient fluxes in a marine soft bottom sediment. [...]."

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Source: Science Direct 
Authors: Damodar M. Shenoy et al.
DOI: 10.1016/j.jmarsys.2020.103310 

Abstract

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

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Source: Nature 
Authors: Vivien Marx
DOI: 10.1038/s41592-020-0736-9

"Microbiology wants in. No longer should microbes and microbial processes be left out of climate change assessments, state 33 researchers from nine countries in their consensus statement¹, “Scientists’ warning to humanity: microorganisms and climate change.” There’s a “need to act,” the authors write. By underappreciating the importance of microbial processes both on land and in the oceans, “we fundamentally limit our understanding of Earth’s biosphere and response to climate change and thus jeopardize efforts to create an environmentally sustainable future.” [...]."

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Source: Nature 
Authors: Huang Huang et al.
DOI: 10.1038/s41467-020-14302-3

Abstract

"Weddell Sea-derived Antarctic Bottom Water (AABW) is one of the most important deep water masses in the Southern Hemisphere occupying large portions of the deep Southern Ocean (SO) today. While substantial changes in SO-overturning circulation were previously suggested, the state of Weddell Sea AABW export during glacial climates remains poorly understood. [...]."

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Source: Biogeosciences
Authors: Vincent Echevin et al.
DOI: 10.5194/bg-17-3317-2020

Abstract

"The northern Humboldt current system (NHCS or Peru upwelling system) sustains the world's largest small pelagic fishery. While a nearshore surface cooling has been observed off southern Peru in recent decades, there is still considerable debate on the impact of climate change on the regional ecosystem. This calls for more accurate regional climate projections of the 21st century, using adapted tools such as regional eddy-resolving coupled biophysical models. [...]."

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Source: EOS
Author: Sarah Stanley

"Certain parts of Earth’s oceans are so oxygen depleted that they can hardly sustain life. Climate models predict that these “dead zones” will expand as global warming progresses, affecting ecosystems, fisheries, and the climate itself. Now Lengger et al. provide new evidence that such predictions do not adequately account for the activity of anaerobic microbes that consume inorganic carbon within dead zones. [...]."

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Source: Biogeosciences
Authors: Filippos Tagklis et al.
DOI: 10.5194/bg-17-231-2020

Abstract

"Western boundary currents act as transport pathways for nutrient-rich waters from low to high latitudes (nutrient streams) and are responsible for maintaining midlatitude and high-latitude productivity in the North Atlantic and North Pacific. This study investigates the centennial oxygen (O₂) and nutrient changes over the Northern Hemisphere in the context of the projected warming and general weakening of the Atlantic Meridional Overturning Circulation (AMOC) in a subset of Earth system models included in the CMIP5 catalogue. In all models examined, the Atlantic warms faster than the Pacific Ocean, resulting in a greater basin-scale solubility decrease. [...]."

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Source: Springer Link
Authors: Lijing Cheng et al.
DOI: 10.1007/s00376-020-9283-7

"Human-emitted greenhouse gases (GHGs) have resulted in a long-term and unequivocal warming of the planet (IPCC, 2019). More than 90% of the excess heat is stored within the world’s oceans, where it accumulates and causes increases in ocean temperature (Rhein et al., 2013; Abram et al., 2019). Because the oceans are the main repository of the Earth’s energy imbalance, measuring ocean heat content (OHC) is one of the best way to quantify the rate of global warming (Trenberth et al., 2016; Von Schuckmann et al., 2016; Cheng et al., 2018). [...]."

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Source: Ocean Science
Authors: Jongsun Kim et al.
DOI: 10.5194/os-16-45-2020

Abstract

"The coastal Gulf of Mexico (GOM) and coastal sea off the Korean Peninsula (CSK) both suffer from human-induced eutrophication. We used a nitrogen (N) mass balance model in two different regions with different nitrogen input sources to estimate organic carbon fluxes and predict future carbon fluxes under different model scenarios. The coastal GOM receives nitrogen predominantly from the Mississippi and Atchafalaya rivers and atmospheric nitrogen deposition is only a minor component in this region. [...]."

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Source:  Annual Reviews
Authors: John L. Largier
DOI: 10.1146/annurev-marine-010419-011020

Abstract

"Bays in coastal upwelling regions are physically driven and biochemically fueled by their interaction with open coastal waters. Wind-driven flow over the shelf imposes a circulation in the bay, which is also influenced by local wind stress and thermal bay–ocean density differences. Three types of bays are recognized based on the degree of exposure to coastal currents and winds (wide-open bays, square bays, and elongated bays), and the characteristic circulation and stratification patterns of each type are described. Retention of upwelled waters in bays allows for dense phytoplankton blooms that support productive bay ecosystems. [...]."

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Source: Nature
Authors: Ben Bronselaer et al.
DOI: 10.1038/s41561-019-0502-8

Abstract

"The Southern Ocean south of 30° S represents only one-third of the total ocean area, yet absorbs half of the total ocean anthropogenic carbon and over two-thirds of ocean anthropogenic heat. In the past, the Southern Ocean has also been one of the most sparsely measured regions of the global ocean. [...]."

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Source: Science Direct
Authors: Feifei Zhang et al.
DOI: 10.1016/j.epsl.2019.115976

Abstract

"The global Hangenberg Crisis near the Devonian-Carboniferous boundary (DCB) represents one of the major Phanerozoic mass extinction events, which shaped the roots of modern vertebrate biodiversity. Marine anoxia has been cited as the proximate kill mechanism for this event. However, the detailed timing, duration, and extent of global marine redox chemistry changes across this critical interval remain controversial because most of the studies to date only constrain changes in local or regional redox chemistry. [...]."

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Source: Science Direct 
Author: Christopher J.Gobler
DOI: 10.1016/j.hal.2019.101731

Abstract

"Climate change is transforming aquatic ecosystems. Coastal waters have experienced progressive warming, acidification, and deoxygenation that will intensify this century. At the same time, there is a scientific consensus that the public health, recreation, tourism, fishery, aquaculture, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past several decades. [...]."

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Source: Science Direct
Authors: Marcela Cornejo-D’Ottone et al.
DOI: 10.1016/j.chemosphere.2019.125709

Abstract

"Plastic is an allochthonous material to marine ecosystems but is rapidly colonized by marine microbial communities, with an as yet unclear contribution to biogeochemical cycles. In this study, we investigated the influence of an active microbial community grown on microplastic particles (the plastisphere) on CO₂ and N₂O recycling and its potential role in greenhouse gas inventories and air-sea exchange. Microplastics were collected during two cruises (Cimar 21 and FIP Montes Submarinos) from the surface layer (5 m depth) from several contrasting trophic regions of the South Pacific Ocean, i.e., from a transition zone off the eutrophic coastal upwelling of Chile, to a mesotrophic transition area of oceanic seamounts and, finally, to an oligotrophic zone in the South Pacific Subtropical Gyre. [...]."

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Source: Science Direct
Authors: Jessica B. Volz et al.
DOI: 10.1016/j.epsl.2019.116012

Abstract

"Numerous studies have provided compelling evidence that the Pacific Ocean has experienced substantial glacial/interglacial changes in bottom-water oxygenation associated with enhanced carbon dioxide storage in the glacial deep ocean. Under postulated low glacial bottom-water oxygen concentrations (O2bw), redox zonation, biogeochemical processes and element fluxes in the sediments must have been distinctively different during the last glacial period (LGP) compared to current well-oxygenated conditions. [...]."

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Source: Science Direct
Authors: Haiyang Wang et al.
DOI: 10.1016/j.gca.2019.11.028

Abstract

"The Mesoproterozoic Era (1.6-1.0 Ga), long regarded as an interval of sluggish biotic evolution and persistently low atmospheric-oceanic oxygen levels, has become the subject of recent controversy regarding putative large-scale oxygenation events. In this study, we conducted a comprehensive investigation of redox, productivity, seawater sulfate concentrations, and hydrographic conditions for the ∼1.4-1.32-Ga Xiamaling Formation in the shallow Hougou and mid-depth Huangtugui sections in the Yanshan Basin (North China). [...]."

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Source: Science Direct
Authors: James W. Moffett & Christopher R. German
DOI: 10.1016/j.chemgeo.2019.119334

Abstract

"The Western Indian Ocean (WIO) and Eastern Tropical South Pacific (ETSP) are distinctly different regimes, yet they share several important features. These include a strong upwelling system, a large oxygen minimum zone (OMZ) with active denitrification, a spreading center with extensive hydrothermal activity, and a vast oligotrophic upper water column. Here, we show that the distribution and geochemistry of iron shows remarkable similarities as well. [...]."

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Source: Science Direct
Authors: Markus Adloff et al.
DOI: 10.1016/j.epsl.2019.115947

Abstract

"The early Aptian Oceanic Anoxic Event (OAE) 1a represents a major perturbation of the Earth's climate system and in particular the carbon cycle, as evidenced by widespread preservation of organic matter in marine settings and a characteristic negative carbon isotopic excursion (CIE) at its onset, followed by a broad positive CIE. The contemporaneous emplacement of a large igneous province (LIP) is invoked as a trigger for OAE 1a (and OAEs in general), but this link and the ultimate source of the carbon perturbation at the onset of OAEs is still debated. [...]."

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Source: Biogeosciences
Authors: Taavi Liblik et al.
DOI: 10.5194/bg-17-2875-2020

Abstract

"The area off the Changjiang Estuary is under strong impact of fresh water and anthropogenic nutrient load from the Changjiang River. The seasonal hypoxia in the area has variable location and range, but the decadal trend reveals expansion and intensification of the dissolved oxygen (DO) depletion. [...]."

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Source: Biogeosciences
Authors: Karen F. Wishner et al.
DOI: 10.5194/bg-17-2315-2020

Abstract

"Increasing deoxygenation (loss of oxygen) of the ocean, including expansion of oxygen minimum zones (OMZs), is a potentially important consequence of global warming. We examined present day variability of vertical distributions of copepod species in the Eastern Tropical North Pacific (ETNP) living in locations with different water column oxygen profiles and OMZ intensity (lowest oxygen concentration and its vertical extent in a profile). [...]."

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Source: Science Direct
Authors: Ricardo L. Silva et al.
DOI: 10.1016/j.gloplacha.2019.103058

Abstract

"Oceans are the largest, readily exchangeable, superficial carbon reservoir; a current challenge in investigating past and present environments and predict future evolution relates to the role of oceanic carbon in regulating Earths' carbon cycle and climate. At least one paired δ¹³C_carb-TOC decoupling event is noted in the Late Bathonian–Early Callovian. [...]."

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Source: Biogeosciences
Authors: Anna Plass et al.
DOI: 10.5194/bg-17-3685-2020

Abstract

"Sediments in oxygen-depleted marine environments can be an important sink or source of bio-essential trace metals in the ocean. However, the key mechanisms controlling the release from or burial of trace metals in sediments are not exactly understood. Here, we investigate the benthic biogeochemical cycling of Fe and Cd in the oxygen minimum zone off Peru. We combine bottom water profiles, pore water profiles, as well as benthic fluxes determined from pore water profiles and in-situ from benthic chamber incubations along a depth transect at 12° S. In agreement with previous studies, both concentration-depth profiles and in-situ benthic fluxes indicate a Fe release from sediments into bottom waters. [...]."

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Source: Climate of the Past
Authors: Sebastian Beil et al.
DOI: 10.5194/cp-16-757-2020

Abstract

"Oceanic Anoxic Events (OAEs) document major perturbations of the global carbon cycle with repercussions on the Earth’s climate and ocean circulation that are relevant to understand future climate trends. Here, we compare sedimentation patterns, nutrient cycling, organic carbon accumulation and carbon isotope variability across Cretaceous Oceanic Anoxic Events OAE1a and OAE2 in two drill cores with unusually high sedimentation rates from the Vocontian Basin (southern France) and Tarfaya Basin (southern Morocco). [...]."

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Source: Nonlinear Processes in Geophysics 
Authors: João H. Bettencourt et al.
DOI: 10.5194/npg-27-277-2020

Abstract

"We apply a coupled modelling system composed of a state-of-the-art hydrodynamical model and a low complexity biogeochemical model to an idealized Iberian Peninsula upwelling system to identify the main drivers of dissolved oxygen variability and to study its response to changes in the duration of the upwelling season and in phytoplankton growth regime. [...]."

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Source: Biogeosciences 
Authors: Haiyan Zhang et al.
DOI: 10.5194/bg-17-5745-2020

Abstract

"A three-dimensional physical-biological model of the marginal seas of China was used to analyze interannual and intra-seasonal variations in hypoxic conditions and identify the main processes controlling their generation off the Changjiang (or Yangtze River) estuary. The model was compared against available observations and reproduces the observed temporal and spatial variability of physical and biological properties including bottom oxygen. Interannual variations of hypoxic extent in the simulation are partly explained by variations in river discharge but not nutrient load. [...]."

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Source: Biogeosciences
Authors: Fabian Große et al.
DOI: 10.5194/bg-17-2701-2020

Abstract

"In the East China Sea, hypoxia (oxygen ≤ 62.5 mmol m⁻³) is frequently observed off the Changjiang (or Yangtze) River estuary covering up to about 15,000 km². The Changjiang River is a major contributor to hypoxia formation because it discharges large amounts of freshwater and nutrients into the region. However, modelling and observational studies have suggested that intrusions of nutrient-rich oceanic water from the Kuroshio also contribute to hypoxia formation. [...]."

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Source: Ocean Science
Authors: Thomas Neumann et al.
DOI: 10.5194/os-16-767-2020

Abstract

"The Baltic Sea is a semi-enclosed, brackish water sea in northern Europe. The deep basins of the central Baltic Sea regularly show hypoxic conditions. In contrast, the northern parts of the Baltic Sea, the Bothnian Sea and Bay, are well oxygenated. Lateral inflows or a ventilation due to convection are possible mechanisms for high oxygen concentrations in the deep water of the northern Baltic Sea. [...]."

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Source: Biogeosciences
Authors: Christine Rooks et al.
DOI: 10.5194/bg-17-1231-2020

Abstract

"Sponges are commonly known as general nutrient providers for the marine ecosystem, recycling organic matter into various forms of bio-available nutrients such as ammonium and nitrate. In this study we challenge this view. We show that nutrient removal through microbial denitrification is a common feature in six cold-water sponge species from boreal and Arctic sponge grounds. [...]."

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Source: Biogeosciences
Authors: Lothar Stramma et al.
DOI: 10.5194/bg-17-813-2020

Abstract

"A strong oxygen deficient layer is located in the upper layer of the tropical Pacific Ocean and at deeper depths in the North Pacific. Processes related to climate change (upper ocean warming, reduced ventilation) are expected to change ocean oxygen and nutrient inventories. In most ocean basins, a decrease in oxygen (‘deoxygenation’) and an increase of nutrients has been observed in subsurface layers. Deoxygenation trends are not linear and there could be other influences on oxygen and nutrient trends and variability. Here oxygen and nutrient time series since 1950 in the Pacific Ocean were investigated at 50 to 300 m depth, as this layer provides critical pelagic habitat for biological communities. [...]."

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Source: Science Direct
Authors: Larissa Menezes et al.
DOI: 10.1016/j.jmarsys.2018.05.007

Abstract

"Oxygen minimum zones (OMZs) are unique, widely spread and well-studied features of the global ocean, varying in seasonality and intensity. The Northern Indian Ocean contains OMZs in the Arabian Sea (AS-OMZ) and the Bay of Bengal (BB-OMZ) having unique biogeochemical features. OMZ water column harbours distinct microbial communities that play vital roles in ocean biogeochemical cycles. [...]."

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Source: Science Direct
Authors: Bożena Wojtasiewicz et al.
DOI: 10.1016/j.jmarsys.2018.07.002

Abstract

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

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Source: Biogeosciences 
Authors: Frances E. Hopkins et al.
DOI: 10.5194/bg-17-163-2020

Abstract

"Emissions of dimethylsulfide (DMS) from the polar oceans play a key role in atmospheric processes and climate. Therefore, it is important we increase our understanding of how DMS production in these regions may respond to environmental change. The polar oceans are particularly vulnerable to ocean acidification (OA). However, our understanding of the polar DMS response is limited to two studies conducted in Arctic waters, where in both cases DMS concentrations decreased with increasing acidity. [...]."

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