News

Extinction of cold-water corals on the Namibian shelf due to low oxygen contents

"They were also able to link this event with a shift in the Benguela upwelling system, and an associated intensification of the oxygen minimum zone in this region. The team has now published their findings in the journal Geology.

Known as 'ecosystem engineers', cold-water corals play an important role in the species diversity of the deep sea. The coral species Lophelia pertusa is significantly involved in reef formation. [...]"

Source: EurekAlert!

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Ocean Deoxygenation and Copepods: Coping with Oxygen Minimum Zone Variability

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). [...]"

Source: Biogeosciences
Authors: Karen F. Wishner, Brad Seibel, and Dawn Outram
DOI: 10.5194/bg-2019-394

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Coral Mortality Event in the Flower Garden Banks of the Gulf of Mexico in July 2016: Local Hypoxia due to Cross-Shelf Transport of Coastal Flood Water

Abstract.

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

Source: Continental Shelf Research
Authors: Matthieu Le Hénaff et al.
DOI: 10.1016/j.csr.2019.103988

Read the full article here.


Oceanic organic carbon as a possible first-order control on the carbon cycle during the Bathonian–Callovian

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 δ13Ccarb-TOC decoupling event is noted in the Late Bathonian–Early Callovian. [...]"

Source: Global and Planetary Change
Authors: Ricardo L.Silva et al.
DOI: 10.1016/j.gloplacha.2019.103058


Read the full article here.


Defining CO2 and O2 syndromes of marine biomes in the Anthropocene

Abstract.

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

Source: Global Change Biology
Authors: Shannon G. Klein et al.
DOI: 10.1111/gcb.14879

Read the full article here.


Air–sea fluxes of greenhouse gases and oxygen in the northern Benguela Current region during upwelling events

Abstract.

"Ground-based atmospheric observations of CO2δ(O2∕N2), N2O, and CH4 were used to make estimates of the air–sea fluxes of these species from the Lüderitz and Walvis Bay upwelling cells in the northern Benguela region, during upwelling events. Average flux densities (±1σ) were 0.65±0.4 µmol m−2 s−1 for CO2, −5.1±2.5 µmol m−2 s−1 for O2 (as APO), 0.61±0.5 nmol m−2 s−1 for N2O, and 4.8±6.3 nmol m−2 s−1 for CH4. A comparison of our top-down (i.e., inferred from atmospheric anomalies) flux estimates with shipboard-based measurements showed that the two approaches agreed within ±55 % on average, though the degree of agreement varied by species and was best for CO2. [...]"

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

Read the full article here.


Present climate trends and variability in thermohaline properties of the northern Adriatic shelf

Abstract.

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

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

Read the full article here.


Seasonal variability of the southern tip of the Oxygen Minimum Zone in the eastern South Pacific (30°‐38°S): A modeling study

Abstract.

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

Source: JGR Oceans
Authors: Matias Pizarro‐Koch et al.
DOI: 10.1029/2019JC015201

Read the full article here.


Stable aerobic and anaerobic coexistence in anoxic marine zones

Abstract.

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

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

Read the full article here.


Ocean-Atmosphere Observations in Philippine Sea by Moored Buoy

Abstract.

"Offequatorial extension of equatorial buoy arrays such as Tropical Atmosphere and Ocean/Triangle Trans-Ocean Buoy Network (TAO/TRITON) buoy array is required to monitor global and regional climates. On December 3, 2016, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) deployed a moored buoy (Ph buoy) at 13°N, 137° E in the Philippine Sea and are measuring temperature, salinity, and dissolved oxygen concentration from the sea surface to 300 m and atmospheric parameters. [...]"

Source: MTS/IEEE Kobe Techno-Oceans (OTO), 2018 OCEANS
Authors: Akira Nagano  et al.
DOI: 10.1109/OCEANSKOBE.2018.8558886

Read the full article here.


The control of hydrogen sulfide on benthic iron and cadmium fluxes in the oxygen minimum zone off Peru

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. [...]"

Source: Biogeosciences  (Preprint)
Authors: Anna Plass et al.
DOI: 10.5194/bg-2019-390

Read the full article here.


BFAR explains causes of Metro Manila fish kill

"THE  fish kill in the coastal areas of Las Piñas and Parañaque was not caused by blast fishing but from the poor level of oxygen and high levels of ammonia and phosphates in said water body.

Based on the tests conducted by the Bureau of Fisheries and Aquatic Resources-National Fisheries Laboratory Division and BFAR 4A on the water quality in three sampling areas, it showed that there is a poor level of dissolved oxygen and higher levels of ammonia and phosphates than the standard level. The  sampling areas were in San Dionisio and Bay City, both in Parañaque. [...]"

Read the full article here.


Using machine learning to understand climate change

"Methane is a potent greenhouse gas that is being added to the atmosphere through both natural processes and human activities, such as energy production and agriculture.

To predict the impacts of human emissions, researchers need a complete picture of the atmosphere’s methane cycle. They need to know the size of the inputs—both natural and human—as well as the outputs. They also need to know how long methane resides in the atmosphere.

To help develop this understanding, Tom Weber, an assistant professor of earth and environmental sciences at the University of Rochester; undergraduate researcher Nicola Wiseman ’18, now a graduate student at the University of California, Irvine; and their colleague Annette Kock at the GEOMAR Helmholtz Centre for Ocean Research in Germany, used data science to determine how much methane is emitted from the ocean into the atmosphere each year.  [...]"

Source: University of Rochester

Read the full article here.


Cretaceous Oceanic Anoxic Events prolonged by phosphorus cycle feedbacks

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). [...]"

Source: Climate of the Past (Preprint)
Authors: Sebastian Beil et al.
DOI: 10.5194/cp-2019-118

Read the full article here.


Sensitivities to global change drivers may correlate positively or negatively in a foundational marine macroalga

Abstract.

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

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

Read the full article here.


Marine nitrogen fixers mediate a low latitude pathway for atmospheric CO2 drawdown

Abstract.

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

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

Read the full article here.


Researchers find global ocean methane emissions dominated by shallow coastal waters

"Methane is a potent greenhouse gas that is being added to the atmosphere through both natural processes and human activities, such as energy production and agriculture.

To predict the impacts of human emissions, researchers need a complete picture of the atmosphere's methane cycle. They need to know the size of the inputs—both natural and human—as well as the outputs. They also need to know how long methane resides in the atmosphere. [...]"

Source: Phys.org

Read the full article here.


Global ocean methane emissions dominated by shallow coastal waters

Abstract.

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

Source: Nature Communications
Authors: Thomas Weber, Nicola A. Wiseman & Annette Kock 
DOI: 10.1038/s41467-019-12541-7

Read the full article here.


Deep Atlantic mysteries unveiled in the face of climate change

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

Source: Cordis

Read the full article here.


Atmosphere–ocean oxygen and productivity dynamics during early animal radiations

Abstract.

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

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

Read the full article here.


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