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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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Application of geoacoustic inference to assess the diurnal effects of photosynthetic activity in a seagrass meadow

Abstract.

"Seagrasses provide a multitude of ecosystem services: they alter water flow, cycle nutrients, stabilize sediments, support the food web structure, and provide a critical habitat for many animals. However, due to threats to seagrass meadows and their associated ecosystems, these habitats are declining globally. Acoustical methods can be a powerful remote sensing tool to efficiently monitor seagrass meadows, alleviating the problem of space and time aliasing associated with traditional spot measurements. [...]"

Source: Earth and Space Science Open Archive
Authors: Megan Ballard et al.
DOI: 10.1002/essoar.10502265.1

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Trends and decadal oscillations of oxygen and nutrients at 50 to 300 m depth in the equatorial and North Pacific

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. [...]"

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

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Short- and long-term impacts of variable hypoxia exposures on kelp forest sea urchins

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. [...]"

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

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