News

Limited oxygen production in the Mesoarchean ocean

Abstract.

"The Archean Eon was a time of predominantly anoxic Earth surface conditions, where anaerobic processes controlled bioessential element cycles. In contrast to “oxygen oases” well documented for the Neoarchean [2.8 to 2.5 billion years ago (Ga)], the magnitude, spatial extent, and underlying causes of possible Mesoarchean (3.2 to 2.8 Ga) surface-ocean oxygenation remain controversial. [...]"

Source: PNAS
Authors: Frantz Ossa Ossa
DOI: 10.1073/pnas.1818762116

Read the full article here.


The influence of decadal oscillations on the oxygen and nutrient trends in the Pacific Ocean

Abstract.

"A strong oxygen deficient layer is located in the upper layer of the tropical Pacific Ocean and at deeper depths 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 of nutrients has been observed in subsurface layers. Deoxygenation trends are not linear and there could be other influences on oxygen and nutrient trends and variability. Here oxygen and nutrient time series since 1950 in the Pacific Ocean were investigated at 50 to 300 m depth, as this layer provides critical pelagic habitat for biological communities. [...]"

Source: Biogeosciences
Authors: Lothar Stramma et al.
DOI: 10.5194/bg-2019-91

Read the full article here.


Seasonal and sub-seasonal oxygen and nutrient fluctuations in an embayment of an eastern boundary upwelling system: St Helena Bay

Abstract.

"Seasonal, sub-seasonal and spatial fluctuations in bottom dissolved oxygen (DO) were examined in St Helena Bay, South Africa’s largest and most productive embayment, between November 2013 and November 2014. Alongshore bay characteristics were assessed through comparison of variables along the 50-m depth contour. A mean coefficient of variation of 0.35 provided a measure of the relative variability of near-bottom DO concentrations along this contour. Consistently lower DO concentrations in the southern region of the bay in summer and autumn are attributed to enhanced retention. [...]"

Source: African Journal of Marine Science (2017)
Authors: GC Pitcher & TA Probyn
DOI: 10.2989/1814232X.2017.1305989

Read the full article here.


Phytoplankton calcifiers control nitrate cycling and the pace of transition in warming icehouse and cooling greenhouse climates

Abstract.

"Phytoplankton calcifiers contribute to global carbon cycling through their dual formation of calcium carbonate and particulate organic carbon (POC). The carbonate might provide an efficient export pathway for the associated POC to the deep ocean, reducing the particles' exposure to biological degradation in the upper ocean and increasing the particle settling rate. Previous work has suggested ballasting of POC by carbonate might increase in a warming climate, in spite of increasing carbonate dissolution rates, because calcifiers benefit from the widespread nutrient limitation arising from stratification. [...]"

Source: Biogeosciences
Authors: Karin F. Kvale et al.
DOI: 10.5194/bg-16-1019-2019

Read the full article here.


The microbiomes of deep-sea hydrothermal vents: distributed globally, shaped locally

Abstract.

"The discovery of chemosynthetic ecosystems at deep-sea hydrothermal vents in 1977 changed our view of biology. Chemosynthetic bacteria and archaea form the foundation of vent ecosystems by exploiting the chemical disequilibrium between reducing hydrothermal fluids and oxidizing seawater, harnessing this energy to fix inorganic carbon into biomass. [...]"

Source: Nature Reviews Microbiology
Author: Gregory J. Dick
DOI: 10.1038/s41579-019-0160-2

Read the full article here.


Uncovering mechanisms of global ocean change effects on the Dungeness crab (Cancer magister) through metabolomics analysis

Abstract.

"The Dungeness crab is an economically and ecologically important species distributed along the North American Pacific coast. To predict how Dungeness crab may physiologically respond to future global ocean change on a molecular level, we performed untargeted metabolomic approaches on individual Dungeness crab juveniles reared in treatments that mimicked current and projected future pH and dissolved oxygen conditions. We found 94 metabolites and 127 lipids responded in a condition-specific manner, with a greater number of known compounds more strongly responding to low oxygen than low pH exposure. [...]"

Source: bioRxiv
Authors: Shelly A. Trigg et al.
DOI: 10.1101/574798

Read the full article here.


Bacterial fermentation and respiration processes are uncoupled in anoxic permeable sediments

Abstract.

"Permeable (sandy) sediments cover half of the continental margin and are major regulators of oceanic carbon cycling. The microbial communities within these highly dynamic sediments frequently shift between oxic and anoxic states, and hence are less stratified than those in cohesive (muddy) sediments. A major question is, therefore, how these communities maintain metabolism during oxic–anoxic transitions. [...]"

Source: Nature Microbiology
Authors: Adam J. Kessler et al.
DOI: 10.1038/s41564-019-0391-z

Read the full article here.


Seasonal Variability of the Mauritania Current and Hydrography at 18°N

Abstract.

"Extensive field campaigns in the Mauritanian upwelling region between 2005 and 2016 provide the database for analyzing the seasonal variability of the eastern boundary circulation (EBC) and associated water mass distribution at 18°N. The data set includes shipboard upper ocean current, hydrographic, and oxygen measurements from nine research cruises conducted during upwelling (December to April) and relaxation (May to July) seasons. [...]"

Source: JGR Oceans
Authors: T. Klenz, M. Dengler and P. Brandt
DOI: 10.1029/2018JC014264

Read the full article here.


Efficient recycling of nutrients in modern and past hypersaline environments

Abstract.

"The biogeochemistry of hypersaline environments is strongly influenced by changes in biological processes and physicochemical parameters. Although massive evaporation events have occurred repeatedly throughout Earth history, their biogeochemical cycles and global impact remain poorly understood. Here, we provide the first nitrogen isotopic data for nutrients and chloropigments from modern shallow hypersaline environments (solar salterns, Trapani, Italy) and apply the obtained insights to δ15N signatures of the Messinian salinity crisis (MSC) in the late Miocene. [...]"

Source: Scientific Reports
Authors: Y. Isaji et al.
DOI: 10.1038/s41598-019-40174-9

Read the full article here.


Diversity of culturable Sulphur-oxidising bacteria in the oxygen minimum zones of the northern Indian Ocean

Abstract.

"Oxygen minimum zones (OMZs) are unique, widely spread and well-studied features of the global ocean, varying in seasonality and intensity. The Northern Indian Ocean contains OMZs in the Arabian Sea (AS-OMZ) and the Bay of Bengal (BB-OMZ) having unique biogeochemical features. OMZ water column harbours distinct microbial communities that play vital roles in ocean biogeochemical cycles. Sulphur cycling processes facilitated by OMZ microbial communities are poorly understood with regards to different microbial groups involved, spatially and temporally. [...]"

Source: Journal of Marine Systems (2018)
Authors: Larissa Menezes et al.
DOI: 10.1016/j.jmarsys.2018.05.007

Read the full article here.


Showing 1 - 10 of 457 results.
Items per Page 10
of 46