scholarly journals Development, Productivity, and Seasonality of Living Planktonic Foraminiferal Faunas and Limacina helicina in an Area of Intense Methane Seepage in the Barents Sea

2020 ◽  
Vol 125 (2) ◽  
Author(s):  
Siri Ofstad ◽  
Julie Meilland ◽  
Katarzyna Zamelczyk ◽  
Melissa Chierici ◽  
Agneta Fransson ◽  
...  
Keyword(s):  
Barents Sea ◽  
Methane Seepage ◽  
The Barents Sea ◽  
Limacina Helicina

Dynamics of methane seepage at Leirdjupet Fault Complex (SW Barents Sea) since last deglaciation and possible future scenarios

2021 ◽  
Author(s):  
Claudio Argentino ◽  
Kate Waghorn ◽  
Sunil Vadakkepuliyambatta ◽  
Stéphane Polteau ◽  
Stefan Bünz ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Barents Sea ◽  
Ice Sheet ◽  
Methane Emissions ◽  
Anaerobic Oxidation Of Methane ◽  
Last Deglaciation ◽  
Methane Seeps ◽  
Geochemical Composition ◽  
Methane Seepage ◽  
The Barents Sea

<p>Methane emissions from Arctic continental margins may increase due to global warming. Present-day ocean fluxes seem to provide a minor contribution to the atmosphere methane pool, but large uncertainties still remain on the magnitude of future emissions from methane seeps and gas hydrate-bearing sediments. The Barents Sea is a natural laboratory to study the evolution of methane seeps in relation to climate change, as it recorded several phases of ice-sheet advance and retreat during the Pleistocene. Glaciations and its concurrent denudation of the Barents Sea influenced the subsurface, causing reservoir expansion and fracturing, thereby driving hydrocarbon (mostly gas) migration which resulted in a sustained regional fluid flow system. New data from this area can shed light on future response of other high-latitude continental shelves worldwide. Here, we present reconstructed methane emission dynamics at Leirdjupet Fault Complex (LFC), SW Barents Sea, since last deglaciation (occurred after ~19 cal Ka BP). The geochemical composition of sediment cores indicate prolonged methane emissions, which started after 14.5 cal Ka BP. Geochemical proxies for anaerobic oxidation of methane in the sediment (barium, calcium and sulfur enrichments, isotopic composition of foraminifera) indicate an overall decrease in seepage intensity over the Holocene toward present-day conditions. Methane-derived authigenic carbonates with aragonite mineralogy and heavy δ<sup>18</sup>O signature recorded an episode of gas hydrate destabilization in this region. Paleo-hydrate stability models suggest that this event was triggered by the influx of warm Atlantic water and isostatic uplift linked to the retreat of the Barents Sea Ice Sheet. Present-day distribution of methane seeps at LFC is strongly linked to underlying faults. Methane hydrates are stable in the southern part of the investigated seepage area and might respond to a future increase in bottom water temperatures.</p>

scholarly journals Shell density of planktonic foraminifera and pteropod species Limacina helicina in the Barents Sea: Relation to ontogeny and water chemistry

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249178
Author(s):  
Siri Ofstad ◽  
Katarzyna Zamelczyk ◽  
Katsunori Kimoto ◽  
Melissa Chierici ◽  
Agneta Fransson ◽  
...  
Keyword(s):  
Water Depth ◽  
Barents Sea ◽  
Planktonic Foraminifera ◽  
Chemical Properties ◽  
Specific Area ◽  
Shell Size ◽  
Neogloboquadrina Pachyderma ◽  
The Barents Sea ◽  
Limacina Helicina ◽  
Physical And Chemical

Planktonic calcifiers, the foraminiferal species Neogloboquadrina pachyderma and Turborotalita quinqueloba, and the thecosome pteropod Limacina helicina from plankton tows and surface sediments from the northern Barents Sea were studied to assess how shell density varies with depth habitat and ontogenetic processes. The shells were measured using X-ray microcomputed tomography (XMCT) scanning and compared to the physical and chemical properties of the water column including the carbonate chemistry and calcium carbonate saturation of calcite and aragonite. Both living L. helicina and N. pachyderma increased in shell density from the surface to 300 m water depth. Turborotalita quinqueloba increased in shell density to 150–200 m water depth. Deeper than 150 m, T. quinqueloba experienced a loss of density due to internal dissolution, possibly related to gametogenesis. The shell density of recently settled (dead) specimens of planktonic foraminifera from surface sediment samples was compared to the living fauna and showed a large range of dissolution states. This dissolution was not apparent from shell-surface texture, especially for N. pachyderma, which tended to be both thicker and denser than T. quinqueloba. Dissolution lowered the shell density while the thickness of the shell remained intact. Limacina helicina also increase in shell size with water depth and thicken the shell apex with growth. This study demonstrates that the living fauna in this specific area from the Barents Sea did not suffer from dissolution effects. Dissolution occurred after death and after settling on the sea floor. The study also shows that biomonitoring is important for the understanding of the natural variability in shell density of calcifying zooplankton.

Method application of optimal multi-parameter analysis to assess the distribution of water masses as an example of CTD data of the Barents Sea in summer 2017

2019 ◽  
pp. 38-51
Author(s):  
Valeriy G. Yakubenko ◽  
Anna L. Chultsova
Keyword(s):  
Barents Sea ◽  
Field Measurements ◽  
Structural Similarity ◽  
Water Masses ◽  
Parameter Analysis ◽  
Water Dynamics ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
The Barents Sea ◽  
Expert Assessments

Identification of water masses in areas with complex water dynamics is a complex task, which is usually solved by the method of expert assessments. In this paper, it is proposed to use a formal procedure based on the application of the method of optimal multiparametric analysis (OMP analysis). The data of field measurements obtained in the 68th cruise of the R/V “Academician Mstislav Keldysh” in the summer of 2017 in the Barents Sea on the distribution of temperature, salinity, oxygen, silicates, nitrogen, and phosphorus concentration are used as a data for research. A comparison of the results with data on the distribution of water masses in literature based on expert assessments (Oziel et al., 2017), allows us to conclude about their close structural similarity. Some differences are related to spatial and temporal shifts of measurements. This indicates the feasibility of using the OMP analysis technique in oceanological studies to obtain quantitative data on the spatial distribution of different water masses.

Surface temperatures of the Barents Sea

1990 ◽  
Vol 8 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Lars Midttun
Keyword(s):  
Barents Sea ◽  
The Barents Sea ◽  
Surface Temperatures
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