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Phosphorus-limited conditions in the early Neoproterozoic ocean maintained low levels of atmospheric oxygen

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. [...]"

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

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I/Ca in epifaunal benthic foraminifera: A semi-quantitative proxy for bottom water oxygen in a multi-proxy compilation for glacial ocean deoxygenation

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. [...]"

Source: Earth and Planetary Science Letters
Authors: Wanyi Lu et al.
DOI: 10.1016/j.epsl.2019.116055


Global certified-reference-material- or reference-material-scaled nutrient gridded dataset GND13

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. [...]"

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

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Neritic ecosystem response to Oceanic Anoxic Event 2 in the Cretaceous Western Interior Seaway, USA

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. [...]"

Source: Palaeogeography, Palaeoclimatology, Palaeoecology
Authors: F. Garrett Boudinot et al.
DOI: 10.1016/j.palaeo.2020.109673

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Defining Southern Ocean fronts and their influence on biological and physical processes in a changing climate

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. [...]"

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

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Millennial-scale variations in sedimentary oxygenation in the western subtropical North Pacific and its links to North Atlantic climate

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. [...]"

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

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Bioaccumulation of Trace Elements in Myctophids in the Oxygen Minimum Zone Ecosystem of the Gulf of California

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. [...]"

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

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Sweden becomes latest nation to join Global Ocean Alliance

"Sweden has become the newest member of the UK’s Global Ocean Alliance, which looks to help drive urgent action towards the 30by30 target, which would safeguard 30% of the ocean by 2030 and so helping to protect marine wildlife.

“Sweden together with Fiji, hosted the first UN ocean conference in 2017, and we firmly believe we need more international cooperation and substantially increased ambitions to help our ocean survive under the increasing pressures of overfishing, pollution and climate change,” said Swedish Minister for Environment and Climate, Isabella Lövin. [...]"

Source: Oceanographic

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Discovery and Mapping of the Triton Seep Site, Redondo Knoll: Fluid Flow and Microbial Colonization Within an Oxygen Minimum Zone

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. [...]"

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

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Seeding oceans with iron may not impact climate change

"Study finds Earth's oceans contain just the right amount of iron; adding more may not improve their ability to absorb carbon dioxide

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.

To help stem escalating carbon dioxide emissions produced by the burning of fossil fuels, some scientists have proposed seeding the oceans with iron -- an essential ingredient that can stimulate phytoplankton growth. Such "iron fertilization" would cultivate vast new fields of phytoplankton, particularly in areas normally bereft of marine life. [...]"

Source: Sciencedaily

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