Oxygen Optode Sensors: Principle, Characterization, Calibration, and Application in the Ocean


"Recently, measurements of oxygen concentration in the ocean—one of the most classical parameters in chemical oceanography—are experiencing a revival. This is not surprising, given the key role of oxygen for assessing the status of the marine carbon cycle and feeling the pulse of the biological pump. The revival, however, has to a large extent been driven by the availability of robust optical oxygen sensors and their painstakingly thorough characterization. For autonomous observations, oxygen optodes are the sensors of choice: They are used abundantly on Biogeochemical-Argo floats, gliders and other autonomous oceanographic observation platforms.  [...]"

Source: Frontiers in Marine Science
Authors: Henry C. Bittig et al.
DOI: 10.3389/fmars.2017.00429

Read the full article here.

Biogeochemical Role of Subsurface Coherent Eddies in the Ocean: Tracer Cannonballs, Hypoxic Storms, and Microbial Stewpots?


"Subsurface eddies are known features of ocean circulation, but the sparsity of observations prevents an assessment of their importance for biogeochemistry. Here we use a global eddying (0.1°) ocean-biogeochemical model to carry out a census of subsurface coherent eddies originating from eastern boundary upwelling systems (EBUS) and quantify their biogeochemical effects as they propagate westward into the subtropical gyres.  [...]"

Source: Global Biogeochemical Cycles
Authors: Ivy Frenger et al.
DOI: 10.1002/2017GB005743

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Influence of an oxygen minimum zone and macroalgal enrichment on benthic megafaunal community composition in a NE Pacific submarine canyon


"Megafaunal diversity in the deep sea shows a parabolic pattern with depth. It can be affected by factors such as low oxygen concentration, which suppresses diversity, or the presence of submarine canyons, which enhances it. Barkley Canyon, located off the west coast of British Columbia, Canada, is a submarine canyon that extends from the continental margin (200 m) into the deep ocean (2,000 m).  [...]"

Source: marine ecology
Authors: Lia Domke et al.
DOI: 10.1111/maec.12481

Read the full article here.

Dealing with Dead Zones: Hypoxia in the Ocean

When water runs off of farmland and urban centers and flows into our streams and rivers, it is often chock-full of fertilizers and other nutrients. These massive loads of nutrients eventually end up in our coastal ocean, fueling a chain of events that can lead to hypoxic "dead zones" — areas along the sea floor where oxygen is so low it can no longer sustain marine life. In this episode, we're joined by NOAA scientist Alan Lewitus to explore why dead zones form, how the problem of hypoxia is growing worse, and what we're doing about it.

Source: National Oceanic and Atmospheric Administration (NOAA)
Author: Troy Kitch

Read the full article here.

Dimethylsulfide (DMS) production in polar oceans may be resilient to ocean acidification


"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. [...]"

Source: Biogeosciences (under Review)
Authors: Frances E. Hopkins et al.
DOI: 10.5194/bg-2018-55

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Oceanic crustal carbon cycle drives 26-million-year atmospheric carbon dioxide periodicities


"Atmospheric carbon dioxide (CO2) data for the last 420 million years (My) show long-term fluctuations related to supercontinent cycles as well as shorter cycles at 26 to 32 My whose origin is unknown. Periodicities of 26 to 30 My occur in diverse geological phenomena including mass extinctions, flood basalt volcanism, ocean anoxic events, deposition of massive evaporites, sequence boundaries, and orogenic events and have previously been linked to an extraterrestrial mechanism. [...]

Source: Science Advances
Authors: R. Dietmar Müller and Adriana Dutkiewicz
DOI: 10.1126/sciadv.aaq0500

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Ocean science research is key for a sustainable future

"Human activity has already affected all parts of the ocean, with pollution increasing and fish-stocks plummeting. The UN’s recent announcement of a Decade of Ocean Science provides a glimmer of hope, but scientists will need to work closely with decision-makers and society at large to get the ocean back on track. [...]"

Source: Martin Visbeck
Author: Nature Communications
DOI: 10.1038/s41467-018-03158-3

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High total organic carbon in surface waters of the northern Arabian Gulf: Implications for the oxygen minimum zone of the Arabian Sea


"Measurements of total organic carbon (TOC) for two years in Kuwaiti waters showed high TOC levels (101.0–318.4, mean 161.2 μM) with maximal concentrations occurring within the polluted Kuwait Bay and decreasing offshore, indicating substantial anthropogenic component. Analysis of winter-time data revealed a large increase in density over the past four decades due to decrease in Shatt Al-Arab runoff, implying that the dissolved/suspended organic matter in surface waters of the northern Gulf could be quickly injected into the Gulf Deep Water (GDW). [...]"

Source: Marine Pollution Bulletin
Authors: Turki Al-Said et al.
DOI: 10.1016/j.marpolbul.2018.02.013

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Meridional overturning circulation conveys fast acidification to the deep Atlantic Ocean


"Since the Industrial Revolution, the North Atlantic Ocean has been accumulating anthropogenic carbon dioxide (CO2) and experiencing ocean acidification1, that is, an increase in the concentration of hydrogen ions (a reduction in pH) and a reduction in the concentration of carbonate ions. The latter causes the ‘aragonite saturation horizon’—below which waters are undersaturated with respect to a particular calcium carbonate, aragonite—to move to shallower depths (to shoal), exposing corals to corrosive waters. [...]"

Source: Nature
Authors: Fiz F. Perez et al.
DOI: 10.1038/nature25493

Read the full article here.

Carbonate chemistry of an in-situ free-ocean CO2 enrichment experiment (antFOCE) in comparison to short term variation in Antarctic coastal waters


"Free-ocean CO2 enrichment (FOCE) experiments have been deployed in marine ecosystems to manipulate carbonate system conditions to those predicted in future oceans. We investigated whether the pH/carbonate chemistry of extremely cold polar waters can be manipulated in an ecologically relevant way, to represent conditions under future atmospheric CO2 levels, in an in-situ FOCE experiment in Antarctica. [...]"

Source: Scientific Reports
Authors: J. S. Stark et al.
DOI: 10.1038/s41598-018-21029-1

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Earth’s Oceans Suffocate as Climate Change and Nutrient Loading Create “Dead Zones”

"A new research study from a Global Ocean Oxygen Network (GO2NE) team of scientists reveals that the number of low- and zero oxygen sites in the world’s oceans have increased dramatically in the past 50 years. The Intergovernmental Oceanographic Commission of the United Nations created the GO2NE working group to provide a multidisciplinary, global view of deoxygenation, with the end goal of advising policymakers on preserving marine resources by countering low oxygen. [...]"

Source: environmental monitor
Author: Karla Lant

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Effects of ocean acidification and hydrodynamic conditions on carbon metabolism and dissolved organic carbon (DOC) fluxes in seagrass populations


"Global change has been acknowledged as one of the main threats to the biosphere and its provision of ecosystem services, especially in marine ecosystems. Seagrasses play a critical ecological role in coastal ecosystems, but their responses to ocean acidification (OA) and climate change are not well understood. There have been previous studies focused on the effects of OA, but the outcome of interactions with co-factors predicted to alter during climate change still needs to be addressed. [...]"

Source: PLoS ONE
Authors: Luis G. Egea et al.
DOI: 10.1371/journal.pone.0192402

Read the full article here.

The effect of bio-irrigation by the polychaete Lanice conchilega on active denitrifiers: Distribution, diversity and composition of nosZ gene


"The presence of large densities of the piston-pumping polychaete Lanice conchilega can have important consequences for the functioning of marine sediments. It is considered both an allogenic and an autogenic ecosystem engineer, affecting spatial and temporal biogeochemical gradients (oxygen concentrations, oxygen penetration depth and nutrient concentrations) and physical properties (grain size) of marine sediments, which could affect functional properties of sediment-inhabiting microbial communities. [...]"

Source: PLOS
Authors: Maryam Yazdani Foshtomi et al.
DOI: 10.1371/journal.pone.0192391

Read the full article here.

The microbial nitrogen-cycling network


"Nitrogen is an essential component of all living organisms and the main nutrient limiting life on our planet. By far, the largest inventory of freely accessible nitrogen is atmospheric dinitrogen, but most organisms rely on more bioavailable forms of nitrogen, such as ammonium and nitrate, for growth. [...]"

Source: Nature Reviews Microbiology
Authors: Marcel M. M. Kuypers, Hannah K. Marchant & Boran Kartal
DOI: 10.1038/nrmicro.2018.9

Read the full article here.

Response of O2 and pH to ENSO in the California Current System in a high-resolution global climate model


"Coastal upwelling systems, such as the California Current System (CalCS), naturally experience a wide range of O2 concentrations and pH values due to the seasonality of upwelling. Nonetheless, changes in the El Niño–Southern Oscillation (ENSO) have been shown to measurably affect the biogeochemical and physical properties of coastal upwelling regions. In this study, we use a novel, high-resolution global climate model (GFDL-ESM2.6) to investigate the influence of warm and cold ENSO events on variations in the O2 concentration and the pH of the CalCS coastal waters. [...]"

Source: Ocean Science
Authors:  Giuliana Turi et al.
DOI: 10.5194/os-14-69-2018

Read the full article here.

Top Ocean Research Organizations Develop Unified Voice at Scripps Meeting

Global research organization seeks to leverage technological advances to promote ocean protection

"Several dozen of the world’s top oceanographers were at Scripps Institution of Oceanography at the University of California San Diego last week to showcase advances in the technology used to observe the oceans.

At the 19th annual meeting of the Partnership for Observation of the Global Oceans (POGO), which Scripps Oceanography co-founded in 1999, leaders said that the organization has evolved from setting up scientific observation networks in the global oceans to encouraging the spread of oceanographic expertise worldwide. Now, said POGO Chair Karen Wiltshire, the organization seeks to create consensus among scientists to create a global voice calling attention to issues ranging from ocean acidification to deoxygenation and sustainable fishing. [...]"

Source: Scripps Institution of Oceanography

Read the full article here.

Impact of mesoscale eddies on water mass and oxygen distribution in the eastern tropical South Pacific


"The influence of mesoscale eddies on the flow field and the water masses, especially the oxygen distribution of the eastern tropical South Pacific is investigated from a mooring, float and satellite data set. Two anticyclonic (ACE1/2), one mode water (MWE) and one cyclonic eddy (CE) are identified and followed in detail with satellite data on their westward transition with velocities of 3.2 to 6.0 cm/s from their generation region, the shelf of the Peruvian and Chilean upwelling regime, across the Stratus Ocean Reference Station (ORS) (~ 20° S, 85° W) to their decaying region far west in the oligotrophic open ocean. [...]"

Source: Ocean Science (under review)
Authors: Rena Czeschel et al.
DOI: 10.5194/os-2018-5

Read the full article here.


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