scholarly journals Divergent Genomic Adaptations in the Microbiomes of Arctic Subzero Sea-Ice and Cryopeg Brines

2021 ◽  
Vol 12 ◽  
Author(s):  
Josephine Z. Rapp ◽  
Matthew B. Sullivan ◽  
Jody W. Deming
Keyword(s):  
Sea Ice ◽  
Taxonomic Composition ◽  
Environmental Stability ◽  
First Year ◽  
Extreme Conditions ◽  
Secretion Systems ◽  
Bacterial Competition ◽  
Copy Numbers ◽  
Stable Conditions ◽  
Dna Replication And Repair

Subzero hypersaline brines are liquid microbial habitats within otherwise frozen environments, where concentrated dissolved salts prevent freezing. Such extreme conditions presumably require unique microbial adaptations, and possibly altered ecologies, but specific strategies remain largely unknown. Here we examined prokaryotic taxonomic and functional diversity in two seawater-derived subzero hypersaline brines: first-year sea ice, subject to seasonally fluctuating conditions; and ancient cryopeg, under relatively stable conditions geophysically isolated in permafrost. Overall, both taxonomic composition and functional potential were starkly different. Taxonomically, sea-ice brine communities (∼105 cells mL–1) had greater richness, more diversity and were dominated by bacterial genera, including Polaribacter, Paraglaciecola, Colwellia, and Glaciecola, whereas the more densely inhabited cryopeg brines (∼108 cells mL–1) lacked these genera and instead were dominated by Marinobacter. Functionally, however, sea ice encoded fewer accessory traits and lower average genomic copy numbers for shared traits, though DNA replication and repair were elevated; in contrast, microbes in cryopeg brines had greater genetic versatility with elevated abundances of accessory traits involved in sensing, responding to environmental cues, transport, mobile elements (transposases and plasmids), toxin-antitoxin systems, and type VI secretion systems. Together these genomic features suggest adaptations and capabilities of sea-ice communities manifesting at the community level through seasonal ecological succession, whereas the denser cryopeg communities appear adapted to intense bacterial competition, leaving fewer genera to dominate with brine-specific adaptations and social interactions that sacrifice some members for the benefit of others. Such cryopeg genomic traits provide insight into how long-term environmental stability may enable life to survive extreme conditions.

scholarly journals Tank study of physico-chemical controls on gas content and composition during growth of young sea ice

2002 ◽  
Vol 48 (161) ◽  
pp. 177-191 ◽  
Author(s):  
Jean-Louis Tison ◽  
Christian Haas ◽  
Marcia M. Gowing ◽  
Suzanne Sleewaegen ◽  
Alain Bernard
Keyword(s):  
Sea Ice ◽  
Sea Water ◽  
Bubble Nucleation ◽  
Water Dynamics ◽  
Gas Content ◽  
First Year ◽  
Water Interface ◽  
Atmospheric Gases ◽  
Physico Chemical ◽  
Ice Water

AbstractDuring an ice-tank experiment, samples were taken to study the processes of acquisition and alteration of the gas properties in young first-year sea ice during a complete growth–warming–cooling cycle. The goal was to obtain reference levels for total gas content and concentrations of atmospheric gases (O2, N2, CO2) in the absence of significant biological activity. The range of total gas-content values obtained (3.5–18 mL STP kg−1) was similar to previous measurements or estimates. However, major differences occurred between current and quiet basins, showing the role of the water dynamics at the ice–water interface in controlling bubble nucleation processes. Extremely high CO2concentrations were observed in all the experiments (up to 57% in volume parts). It is argued that these could have resulted from two unexpected biases in the experimental settings. Concentrations in bubbles nucleated at the interface are controlled by diffusion both from the ice–water interface towards the well-mixed reservoir and between the interface water and the bubble itself. This double kinetic effect results in a transition of the gas composition in the bubbles from values close to solubility in sea water toward values close to atmospheric, as the ice cover builds up.

scholarly journals Mesoscale distribution and functional diversity of picoeukaryotes in the first-year sea ice of the Canadian Arctic

2013 ◽  
Vol 7 (8) ◽  
pp. 1461-1471 ◽  
Author(s):  
Kasia Piwosz ◽  
Józef Maria Wiktor ◽  
Andrea Niemi ◽  
Agnieszka Tatarek ◽  
Christine Michel
Keyword(s):  
Sea Ice ◽  
Functional Diversity ◽  
Canadian Arctic ◽  
First Year

Seasonal evolution and salt/freshwater fluxes of first-year sea ice: Comparison between pack ice and landfast sea ice 

2021 ◽  
Author(s):  
Marc Oggier ◽  
Hajo Eicken ◽  
Robert Rember ◽  
Allison Fong ◽  
Dmitry V. Divine ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Cores ◽  
Upper Ocean ◽  
First Year ◽  
Ice Melt ◽  
Ice Surface ◽  
Freshwater Fluxes ◽  
Exchange Processes ◽  
Bulk Salinity ◽  
Landfast Sea Ice

<p>Sea ice affects the exchange of energy and matter between the atmosphere and the ocean from local to hemispheric scales. Salt fluxes across the ice-ocean interface that drive thermohaline mixing beneath growing sea ice are important elements of upper ocean nutrient and carbon exchange. Sea-ice melt releases freshwater into the upper ocean and results in formation of melt ponds that affect gas and energy transfer across the atmosphere-ice interface. The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) provided an opportunity to follow sea-ice evolution and exchange processes over a full seasonal cycle in a rapidly changing ice cover. To this end, approximately 25 sea-ice cores were collected at 2 distinct sites, representing first-year and multi-year ice, to monitor physical, biological and geochemical processes relevant to atmosphere-ice-ocean exchange processes. Here we compare the growth and decay of first-year ice in the Central Arctic during the winter 2019-2020 to that of landfast first-year ice at Utqiaġvik, Alaska, from 1998 to 2016. Ice stratigraphy was similar at both sites with about 15 cm of granular ice on top of columnar ice, with a comparable growth history with a similar maximum ice thickness of 1.6-1.7 m. We aggregated the sea-ice bulk salinity and temperature profiles using a degree-day approach, and examined brine and freshwater fluxes at lower and upper interfaces of the ice, respectively. Preliminary results show lower sea-ice bulk salinity during the growth season and greater desalination at the ice surface during the melt season at the MOSAiC floe in comparison to Utqiaġvik.</p>

Arctic sea ice volume budget decomposition satellite product for the CryoSat-2 (2010-2020) period 

2021 ◽  
Author(s):  
Harry Heorton ◽  
Michel Tsamados ◽  
Paul Holland ◽  
Jack Landy
Keyword(s):  
Sea Ice ◽  
Climate Model ◽  
Volume Growth ◽  
Arctic Sea Ice ◽  
First Year ◽  
Sea Ice Concentration ◽  
Marginal Seas ◽  
Ice Volume ◽  
Arctic Sea ◽  
Ice Concentration

<p><span>We combine satellite-derived observations of sea ice concentration, drift, and thickness to provide the first observational decomposition of the dynamic (advection/divergence) and thermodynamic (melt/growth) drivers of wintertime Arctic sea ice volume change. Ten winter growth seasons are analyzed over the CryoSat-2 period between October 2010 and April 2020. Sensitivity to several observational products is performed to provide an estimated uncertainty of the budget calculations. The total thermodynamic ice volume growth and dynamic ice losses are calculated with marked seasonal, inter-annual and regional variations</span><span>. Ice growth is fastest during Autumn, in the Marginal Seas and over first year ice</span><span>. Our budget decomposition methodology can help diagnose the processes confounding climate model predictions of sea ice. We make our product and code available to the community in monthly pan-Arctic netcdft files for the entire October 2010 to April 2020 period.</span></p>

scholarly journals Anomalous blocking over Greenland preceded the 2013 extreme early melt of local sea ice

2017 ◽  
Vol 59 (76pt2) ◽  
pp. 181-190 ◽  
Author(s):  
Thomas J. Ballinger ◽  
Edward Hanna ◽  
Richard J. Hall ◽  
Thomas E. Cropper ◽  
Jeffrey Miller ◽  
...  
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Circulation Pattern ◽  
The Arctic ◽  
Labrador Sea ◽  
First Year ◽  
Tropospheric Circulation ◽  
Blocking Index

ABSTRACTThe Arctic marine environment is undergoing a transition from thick multi-year to first-year sea-ice cover with coincident lengthening of the melt season. Such changes are evident in the Baffin Bay-Davis Strait-Labrador Sea (BDL) region where melt onset has occurred ~8 days decade−1 earlier from 1979 to 2015. A series of anomalously early events has occurred since the mid-1990s, overlapping a period of increased upper-air ridging across Greenland and the northwestern North Atlantic. We investigate an extreme early melt event observed in spring 2013. (~6σ below the 1981–2010 melt climatology), with respect to preceding sub-seasonal mid-tropospheric circulation conditions as described by a daily Greenland Blocking Index (GBI). The 40-days prior to the 2013 BDL melt onset are characterized by a persistent, strong 500 hPa anticyclone over the region (GBI >+1 on >75% of days). This circulation pattern advected warm air from northeastern Canada and the northwestern Atlantic poleward onto the thin, first-year sea ice and caused melt ~50 days earlier than normal. The episodic increase in the ridging atmospheric pattern near western Greenland as in 2013, exemplified by large positive GBI values, is an important recent process impacting the atmospheric circulation over a North Atlantic cryosphere undergoing accelerated regional climate change.

scholarly journals Albedo of Young and First-Year Antarctic Sea Ice

1990 ◽  
Vol 14 ◽  
pp. 331 ◽  
Author(s):  
Richard Brandt ◽  
Ian Allison ◽  
Stephen Warren
Keyword(s):  
Sea Ice ◽  
Radiation Flux ◽  
Open Water ◽  
First Year ◽  
Spectral Measurements ◽  
Antarctic Sea Ice ◽  
Antarctic Expedition ◽  
Downward Radiation ◽  
Radiation Measurements ◽  
Snow Thickness

Reflection of solar radiation was studied in the seasonal sea-ice zone off East Antarctica on a cruise of the Australian Antarctic Expedition, October-December 1988. Spectral and total albedos were measured for grease ice, nilas, young grey ice, grey-white ice, snow-covered ice, and open water. Spectral measurements covered the region 400–1000 nm wavelength. For ice too thin to support our weight, the radiometers were mounted at the end of a 1.5 m rod extended out the door of a helicopter or from a basket hung from the ship's crane, using a positioning and leveling rack. Corrections had to be applied to the downward radiation flux because the helicopter or the crane was in the field of view of the cosine-collector. The fractional coverage of each of the ice types (and open water) was estimated hourly for the region near the ship, as well as the thickness of each ice type, and the snow thickness. Observations were carried out continuously during the four weeks the ship was in the ice, supplemented by occasional helicopter surveys covering larger areas. These observations, together with the radiation measurements, make possible the computation of area-average albedo for the East Antarctic sea-ice zone in spring.

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