News

A crisis in the water is decimating this once-booming fishing town

"TOMBWA, Angola — His ancestors were Portuguese colonialists who settled on this otherworldly stretch of coast, wedged between a vast desert and the southern Atlantic. They came looking for the one thing this barren region had in abundance: fish.

By the time Mario Carceija Santos was getting into the fishing business half a century later, in the 1990s, Angola had won independence and the town of Tombwa was thriving. There were 20 fish factories strung along the bay, a constellation of churches and schools, a cinema hall built in art deco, and, in the central plaza, massive drying racks for the tons upon tons of fish hauled out of the sea. [...]"

Source: The Washington Post

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Article Open Access Published: 29 November 2019 Role of synoptic activity on projected changes in upwelling-favourable winds at the ocean’s eastern bo

Abstract.

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

Source: npj Climate and Atmospheric Science
Authors: Catalina Aguirre et al.
DOI: 10.1038/s41612-019-0101-9

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Global sea-surface iodide observations, 1967–2018

Abstract.

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

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

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Changes in oxygen concentrations in our ocean can disrupt fundamental biological cycles

"New research led by scientists at the University of Bristol has shown that the feedback mechanisms that were thought to keep the marine nitrogen cycle relatively stable over geological time can break down when oxygen levels in the ocean decline significantly.

The nitrogen cycle is essential to all forms of life on Earth - nitrogen is a basic building block of DNA.The marine nitrogen cycle is strongly controlled by biology and small changes in the marine nitrogen cycle have major implications on life. [...]"

Source: University of Bristol

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Fundamentally different global marine nitrogen cycling in response to severe ocean deoxygenation

Abstract.

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

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

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Large projected decline in dissolved oxygen in a eutrophic estuary due to climate change

Abstract.

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

Source: JGR Oceans
Authors: Wenfei Ni et al. 
DOI: 10.1029/2019JC015274

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Dead-zone report card reflects improving water quality in Chesapeake Bay

"An annual model-based report on "dead-zone" conditions in the Chesapeake Bay during 2019 indicates the total volume of low-oxygen, "hypoxic" water was on the high end of the normal range for 1985 to 2018, a finding that scientists consider relatively good news.

 

Dr. Marjy Friedrichs, a Virginia Institute of Marine Science professor and report card co-author, says "Even with environmental conditions that favor severe hypoxia, including record-high river input and light winds, our analysis shows that the total amount of hypoxia this year was within the normal range seen over the past 35 years."

Source: Phys.org

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Distribution of iron in the Western Indian Ocean and the Eastern tropical South pacific: An inter-basin comparison

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. [...]"

Source: Chemical Geology
Authors: James W. Moffett and Christopher R. German
DOI: 10.1016/j.chemgeo.2019.119334

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Ocean studies look at microscopic diversity and activity across entire planet

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

Source: Science Daily

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Unravelling the sources of carbon emissions at the onset of Oceanic Anoxic Event (OAE) 1a

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. [...]"

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

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Spatiotemporal changes of ocean carbon species in the western North Pacific using parameterization technique

Abstract.

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

Source: Journal of Oceanography
Authors: Yutaka W. Watanabe et al.
DOI: 10.1007/s10872-019-00532-7

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Response of N2O production rate to ocean acidification in the western North Pacific

Abstract.

"Ocean acidification, induced by the increase in anthropogenic CO2 emissions, has a profound impact on marine organisms and biogeochemical processes1. The response of marine microbial activities to ocean acidification might play a crucial role in the future evolution of air–sea fluxes of biogenic gases such as nitrous oxide (N2O), a strong GHG and the dominant stratospheric ozone-depleting substance2. Here, we examine the response of N2O production from nitrification to acidification in a series of incubation experiments conducted in subtropical and subarctic western North Pacific. [...]"

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

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Meeting climate targets by direct CO2 injections: what price would the ocean have to pay?

Abstract.

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

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

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Controls on redox-sensitive trace metals in the Mauritanian oxygen minimum zone

Abstract.

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

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

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Climatic, physical, and biogeochemical changes drive rapid oxygen loss and recovery in a marine ecosystem

Abstract.

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

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

Read the full article here.


The Development and Validation of a Profiling Glider Deep ISFET-Based pH Sensor for High Resolution Observations of Coastal and Ocean Acidification

Abstract.

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

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

Read the full article here.

 


Decadal acidification in Atlantic and Mediterranean water masses exchanging at the Strait of Gibraltar

Abstract.

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

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

Read the full article here.


Perspectives on in situ Sensors for Ocean Acidification Research

Abstract.

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

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

Read the full article here.


Wind-driven stratification patterns and dissolved oxygen depletion in the area off the Changjiang (Yangtze) Estuary

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. [...]"

Source: Biogeosciences
Authors: Taavi Liblik et al.
DOI: 10.5194/bg-2019-421

Read the full article here.


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