News

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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Observed spatiotemporal variation of three-dimensional structure and heat/salt transport of anticyclonic mesoscale eddy in Northwest Pacific

Abstract.

"As in-situ observations are sparse, targeted observations of a specific mesoscale eddy are rare. Therefore, it is difficult to study the three-dimensional structure of moving mesoscale eddies. From April to September 2014, an anticyclonic eddy located at 135°E–155°E, 26°N–42°N was observed using 17 rapid-sampling Argo floats, and the spatiotemporal variations in the three-dimensional structure were studied. [...]"

Source: Journal of Oceanology and Limnology
Authors: Jun Dai et al.
DOI: 10.1007/s00343-019-9148-z

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Enhanced Organic Carbon Burial in Sediments of Oxygen Minimum Zones Upon Ocean Deoxygenation

Abstract.

"Oxygen minimum zones (OMZs) in the ocean are expanding. This expansion is attributed to global warming and may continue over the next 10 to 100 kyrs due to multiple climate CO2-driven factors. The expansion of oxygen-deficient waters has the potential to enhance organic carbon burial in marine sediments, thereby providing a negative feedback on global warming. Here, we study the response of dissolved oxygen in the ocean to increased phosphorus and iron inputs due to CO2-driven enhanced weathering and increased dust emissions, respectively. [...]"

Source: Frontiers in Marine Science
Authors: Itzel Ruvalcaba Baroni et al.
DOI: 10.3389/fmars.2019.00839

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Carbon cycling in the world's deepest blue hole

Abstract.

"Blue holes are unique geomorphological features with steep biogeochemical gradients and distinctive microbial communities. Carbon cycling in blue holes, however, remains poorly understood. Here we describe potential mechanisms of dissolved carbon cycling in the world's deepest blue hole, the Yongle Blue Hole (YBH), which was recently discovered in the South China Sea. In the YBH, we found some of the lowest concentrations (e.g., 22 μM) and oldest ages (e.g., 6,810 years BP) of dissolved organic carbon, as well as the highest concentrations (e.g., 3,090 μM) and the oldest ages (e.g., 8270 years BP) of dissolved inorganic carbon observed in oceanic waters. [...]"

Source: JGR Biogeosciences
Authors: P. Yao et al.
DOI: 10.1029/2019JG005307

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Regional nutrient decrease drove redox stabilisation and metazoan diversification in the late Ediacaran Nama Group, Namibia

Abstract.

"The late Ediacaran witnessed an increase in metazoan diversity and ecological complexity, marking the inception of the Cambrian Explosion. To constrain the drivers of this diversification, we combine redox and nutrient data for two shelf transects, with an inventory of biotic diversity and distribution from the Nama Group, Namibia (~550 to ~538 Million years ago; Ma). Unstable marine redox conditions characterised all water depths in inner to outer ramp settings from ~550 to 547 Ma, when the first skeletal metazoans appeared. [...]"

Source: Scientific Reports
Authors: F. T. Bowyer et al.
DOI: 10.1038/s41598-020-59335-2

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The role of water masses in shaping the distribution of redox active compounds in the Eastern Tropical North Pacific oxygen deficient zone

and influencing low oxygen concentrations in the eastern Pacific Ocean

Abstract.

"Oceanic oxygen deficient zones (ODZs) influence global biogeochemical cycles in a variety of ways, most notably by acting as a sink for fixed nitrogen (Codispoti et al. 2001). Optimum multiparameter analysis of data from two cruises in the Eastern Tropical North Pacific (ETNP) was implemented to develop a water mass analysis for the large ODZ in this region. This analysis reveals that the most pronounced oxygen deficient conditions are within the 13°C water (13CW) mass, which is distributed via subsurface mesoscale features such as eddies branching from the California Undercurrent. [...]"

Source: Limnology and Oceanography
Authors: Zachary C. Evans et al.
DOI: 10.1002/lno.11412

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Preparatory Meeting Stresses 2020 as a New Chapter of Ocean Action

"Participants at the 2020 UN Ocean Conference Preparatory Meeting highlighted the importance of a healthy ocean in implementing and achieving the SDGs and stressed that 2020 must be a year of concrete action for the ocean. The 2020 Ocean Conference is one of the first milestones of the UN Secretary-General’s Decade of Action for the SDGs and is expected to provide inputs into the High-level Political Forum on Sustainable Development (HLPF) and the UN Decade of Ocean Science for Sustainable Development. [...]"

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No “Ocean Super-Year” without Marine Regions

"This new decade starts at a critical moment for the future of the Ocean. There is strong agreement among experts that decisions taken in the next ten years will be critical for the future of the Ocean. The current ecological crisis demands a radical shift in the way we treat the marine environment, its precious wildlife, and its invaluable natural resources. We are witnessing continued loss of biodiversity, overfishing, habitat destruction, pollution, and many other serious impacts from human activities – all compounded by climate change, Ocean deoxygenation and acidification. [...]"

Source: International Institute for Sustainable Development

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