scholarly journals Extraordinary Carbon Fluxes on the Shallow Pacific Arctic Shelf During a Remarkably Warm and Low Sea Ice Period

2020 ◽  
Vol 7 ◽  
Author(s):  
Stephanie H. O’Daly ◽  
Seth L. Danielson ◽  
Sarah M. Hardy ◽  
Russell R. Hopcroft ◽  
Catherine Lalande ◽  
...  
Keyword(s):  
Sea Ice ◽  
Carbon Fluxes ◽  
Arctic Shelf ◽  
Ice Period

scholarly journals Bacterial diversity and lipid biomarkers in sea ice and sinking particulate organic material during the melt season in the Canadian Arctic

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Rémi Amiraux ◽  
Jean-François Rontani ◽  
Fabrice Armougom ◽  
Eléonore Frouin ◽  
Marcel Babin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sea Ice ◽  
Organic Material ◽  
Early Stage ◽  
Canadian Arctic ◽  
Carbon Fluxes ◽  
Enzymatic Activities ◽  
Ice Melt ◽  
Sinking Particles ◽  
Potential Biomarkers

The estimation of important carbon fluxes in a changing Arctic environment remains a challenge, one that could benefit from the development of biomarkers that distinguish between sympagic (ice-associated) and pelagic organic material. Products of 10S-DOX-like lipoxygenase and fatty acid cis-trans isomerase (CTI) activity of bacteria attached to sympagic particulate organic matter (POM) were proposed previously as potential biomarkers of the contribution of sympagic biota to carbon fluxes to the seafloor. To date, neither the bacteria involved in such enzymatic activities nor the detection of these potential biomarkers at their presumed source (i.e., sea ice) has been investigated. Here, we determined and compared the diversity of prokaryotic communities (based on operational taxonomic units) attached to sea ice POM and under-ice sinking particles during an early stage of ice melt (brine drainage) in Baffin Bay (Canadian Arctic). Based on a time series of biodiversity analyses and the quantification of lipid tracers of these two bacterial enzymatic activities, we suggest that CTI-active bacteria, exposed to hypersaline stress, are attached to algal POM just above bottom sea ice and released into the water column following brine drainage. In contrast, bacteria attached to sinking particles and exhibiting 10S-DOX-like lipoxygenase activity are suggested to come from the bottommost layer of sea ice, where they may play a role in the detoxification of algae-produce free fatty acids. These results provide a refined view of the potential use of products of CTI activity as specific biomarkers of sympagic organic matter.

Sea ice and life in a river-influenced arctic shelf ecosystem

2008 ◽  
Vol 74 (3-4) ◽  
pp. 739-740 ◽  
Author(s):  
Warwick F. Vincent ◽  
Carlos Pedrós-Alió
Keyword(s):  
Sea Ice ◽  
Arctic Shelf

scholarly journals Methane oxidizing seawater microbial communities from an Arctic shelf

2017 ◽  
Author(s):  
Christiane Uhlig ◽  
John B. Kirkpatrick ◽  
Steve D'Hondt ◽  
Brice Loose
Keyword(s):  
Sea Ice ◽  
Microbial Communities ◽  
Methane Oxidation ◽  
Methane Concentration ◽  
Oxidation Potential ◽  
Arctic Shelf ◽  
Natural Seawater ◽  
Methane Oxidizing Bacteria ◽  
High Concentrations ◽  
Methane Concentrations

Abstract. Microbial communities of the ocean can consume methane dissolved in seawater before it has a chance to escape to the atmosphere and contribute to greenhouse warming. Seawater over the shallow Arctic shelf is characterized by excess methane compared to the atmospheric equilibrium originating in sediments, permafrost and hydrates. Particularly high concentrations are found beneath sea ice. We studied the structure and methane oxidation potential of the microbial communities from seawater collected close to Utqiagvik, Alaska, in April 2016. The in situ methane concentrations were 16.3 ± 7.2 nmol L−1, approximately 4.8 times oversaturated compared to the atmospheric equilibrium. The group of methane oxidizing bacteria (MOB) in the natural seawater and seawater incubations was > 97 % dominated by Methylococcacales (γ-Proteobacteria). Incubations of seawater under a range of methane concentrations led to a loss of diversity in the bacterial community. The abundance of MOB was low with maximal fractions of 2.5 % at 200 times elevated methane concentration, while sequence reads of non-MOB methylotrophs were four times more abundant than MOB in most incubations. The abundances of MOB as well as non-MOB methylotrophs correlated tightly with the rate constant (kox) for methane oxidation, indicating that non-MOB methylotrophs might be coupled to MOB and involved in community methane oxidation. In sea ice, where methane concentrations of 82 ± 35.8 nmol kg−1 were found, Methylobacterium (α-Proteobacteria) was the dominant MOB with a relative abundance of 80 %. MOB abundances were very low in sea ice, with maximal fractions found at the ice-snow interface (0.1 %), while non-MOB-methlylotrophs were present in abundances compared to natural seawater communities. The differences in MOB taxa and an offset in methane concentration and stable isotope ratios between the ice and the water column point toward different methane cycling processes in both habitats.

Contrasts in Arctic shelf sea-ice regimes and some implications: Beaufort Sea versus Laptev Sea

1994 ◽  
Vol 119 (3-4) ◽  
pp. 215-225 ◽  
Author(s):  
Erk Reimnitz ◽  
Dirk Dethleff ◽  
Dirk Nürnberg
Keyword(s):  
Sea Ice ◽  
Beaufort Sea ◽  
Arctic Shelf ◽  
Laptev Sea ◽  
Shelf Sea

scholarly journals Numerical Simulation of Bohai Oil Spill in the Winter Sea Ice Period

2019 ◽  
Vol 33 (2) ◽  
pp. 185-197
Author(s):  
Kun Wang ◽  
Jing Du ◽  
Ming Liu ◽  
Jin-hao Wu ◽  
Heng-zhi Jiang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Sea Ice ◽  
Oil Spill ◽  
Ice Period

scholarly journals Short commentary on marine productivity at Arctic shelf breaks: upwelling, advection and vertical mixing

Ocean Science ◽  
2018 ◽  
Vol 14 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Achim Randelhoff ◽  
Arild Sundfjord
Keyword(s):  
Sea Ice ◽  
Barents Sea ◽  
Dominant Role ◽  
Ice Cover ◽  
Atlantic Water ◽  
Shelf Break ◽  
Arctic Shelf ◽  
The Arctic ◽  
Ample Evidence ◽  
Atlantic Sector

Abstract. The future of Arctic marine ecosystems has received increasing attention in recent years as the extent of the sea ice cover is dwindling. Although the Pacific and Atlantic inflows both import huge quantities of nutrients and plankton, they feed into the Arctic Ocean in quite diverse regions. The strongly stratified Pacific sector has a historically heavy ice cover, a shallow shelf and dominant upwelling-favourable winds, while the Atlantic sector is weakly stratified, with a dynamic ice edge and a complex bathymetry. We argue that shelf break upwelling is likely not a universal but rather a regional, albeit recurring, feature of “the new Arctic”. It is the regional oceanography that decides its importance through a range of diverse factors such as stratification, bathymetry and wind forcing. Teasing apart their individual contributions in different regions can only be achieved by spatially resolved time series and dedicated modelling efforts. The Northern Barents Sea shelf is an example of a region where shelf break upwelling likely does not play a dominant role, in contrast to the shallower shelves north of Alaska where ample evidence for its importance has already accumulated. Still, other factors can contribute to marked future increases in biological productivity along the Arctic shelf break. A warming inflow of nutrient-rich Atlantic Water feeds plankton at the same time as it melts the sea ice, permitting increased photosynthesis. Concurrent changes in sea ice cover and zooplankton communities advected with the boundary currents make for a complex mosaic of regulating factors that do not allow for Arctic-wide generalizations.

scholarly journals Methane-oxidizing seawater microbial communities from an Arctic shelf

2018 ◽  
Vol 15 (11) ◽  
pp. 3311-3329 ◽  
Author(s):  
Christiane Uhlig ◽  
John B. Kirkpatrick ◽  
Steven D'Hondt ◽  
Brice Loose
Keyword(s):  
Sea Ice ◽  
Microbial Communities ◽  
Methane Oxidation ◽  
Oxidation Potential ◽  
Arctic Shelf ◽  
Natural Seawater ◽  
Methane Oxidizing Bacteria ◽  
High Concentrations ◽  
Marine Microbial Communities ◽  
Methane Concentrations

Abstract. Marine microbial communities can consume dissolved methane before it can escape to the atmosphere and contribute to global warming. Seawater over the shallow Arctic shelf is characterized by excess methane compared to atmospheric equilibrium. This methane originates in sediment, permafrost, and hydrate. Particularly high concentrations are found beneath sea ice. We studied the structure and methane oxidation potential of the microbial communities from seawater collected close to Utqiagvik, Alaska, in April 2016. The in situ methane concentrations were 16.3 ± 7.2 nmol L−1, approximately 4.8 times oversaturated relative to atmospheric equilibrium. The group of methane-oxidizing bacteria (MOB) in the natural seawater and incubated seawater was > 97 % dominated by Methylococcales (γ-Proteobacteria). Incubations of seawater under a range of methane concentrations led to loss of diversity in the bacterial community. The abundance of MOB was low with maximal fractions of 2.5 % at 200 times elevated methane concentration, while sequence reads of non-MOB methylotrophs were 4 times more abundant than MOB in most incubations. The abundances of MOB as well as non-MOB methylotroph sequences correlated tightly with the rate constant (kox) for methane oxidation, indicating that non-MOB methylotrophs might be coupled to MOB and involved in community methane oxidation. In sea ice, where methane concentrations of 82 ± 35.8 nmol kg−1 were found, Methylobacterium (α-Proteobacteria) was the dominant MOB with a relative abundance of 80 %. Total MOB abundances were very low in sea ice, with maximal fractions found at the ice–snow interface (0.1 %), while non-MOB methylotrophs were present in abundances similar to natural seawater communities. The dissimilarities in MOB taxa, methane concentrations, and stable isotope ratios between the sea ice and water column point toward different methane dynamics in the two environments.

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