scholarly journals Net heterotrophy in High Arctic first-year and multi-year spring sea ice

Elem Sci Anth ◽  
2022 ◽  
Vol 10 (1) ◽  
Author(s):  
Karley Campbell ◽  
B. A. Lange ◽  
J. C. Landy ◽  
C. Katlein ◽  
M. Nicolaus ◽  
...  
Keyword(s):  
Species Composition ◽  
Sea Ice ◽  
High Arctic ◽  
Algal Community ◽  
First Year ◽  
Light Conditions ◽  
Mixed Composition ◽  
Sampling Campaign ◽  
Variable Light ◽  
Ice Floes

The net productivity of sea ice is determined by the physical and geochemical characteristics of the ice–ocean system and the activity of organisms inhabiting the ice. Differences in habitat suitability between first-year and multi-year sea ice can affect the ice algal community composition and acclimation state, introducing considerable variability to primary production within each ice type. In this study, we characterized the biogeochemical variability between adjacent first-year and multi-year sea ice floes in the Lincoln Sea of the Canadian High Arctic, during the May 2018 Multidisciplinary Arctic Program—Last Ice sampling campaign. Combining measurements of transmitted irradiance from a remotely operated underwater vehicle with laboratory-based oxygen optode incubations, this work shows widespread heterotrophy (net oxygen uptake) in the bottom 10 cm of both ice types, particularly in thick multi-year ice (>2.4 m) and early morning of the 24-h day. Algal acclimation state and species composition varied between ice types despite similar net community production due to widespread light and nutrient limitation. The first-year ice algal community was increasingly dominated over spring by the potentially toxin-producing genus Pseudonitzschia that was acclimated to high and variable light conditions characteristic of a thinner ice habitat with mobile snow cover. In comparison, the multi-year ice harbored more shade-acclimated algae of mixed composition. This work highlights the potential for heterotrophy in sea ice habitats of the High Arctic, including first measurements of such O2-uptake in multi-year ice floes. Observed differences in photophysiology between algae of these sea ice types suggests that a shift toward higher light availability and a younger sea ice cover with climate change does not necessarily result in a more productive system. Instead, it may favor future sea ice algal communities of different species composition, with lower photosynthetic potential but greater resilience to stronger and more variable light conditions.

scholarly journals Upward transport of bottom-ice dimethyl sulfide during advanced melting of arctic first-year sea ice

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Margaux Gourdal ◽  
Odile Crabeck ◽  
Martine Lizotte ◽  
Virginie Galindo ◽  
Michel Gosselin ◽  
...  
Keyword(s):  
Sea Ice ◽  
Dimethyl Sulfide ◽  
The Arctic ◽  
Stable Phase ◽  
First Year ◽  
Sampling Campaign ◽  
Upward Transport ◽  
The Mean ◽  
Strong Control ◽  
Bulk Transport

This paper presents the first empirical estimates of dimethyl sulfide (DMS) gas fluxes across permeable sea ice in the Arctic. DMS is known to act as a major potential source of aerosols that strongly influence the Earth’s radiative balance in remote marine regions during the ice-free season. Results from a sampling campaign, undertaken in 2015 between June 2 and June 28 in the ice-covered Western Baffin Bay, revealed the presence of high algal biomass in the bottom 0.1-m section of sea ice (21 to 380 µg Chl a L–1) combined with the presence of high DMS concentrations (212–840 nmol L–1). While ice algae acted as local sources of DMS in bottom sea ice, thermohaline changes within the brine network, from gravity drainage to vertical stabilization, exerted strong control on the distribution of DMS within the interior of the ice. We estimated both the mean DMS molecular diffusion coefficient in brine (5.2 × 10–5 cm2 s–1 ± 51% relative S.D., n = 10) and the mean bulk transport coefficient within sea ice (33 × 10–5 cm2 s–1 ± 41% relative S.D., n = 10). The estimated DMS fluxes ± S.D. from the bottom ice to the atmosphere ranged between 0.47 ± 0.08 µmol m–2 d–1 (n = 5, diffusion) and 0.40 ± 0.15 µmol m–2 d–1 (n = 5, bulk transport) during the vertically stable phase. These fluxes fall within the lower range of direct summer sea-to-air DMS fluxes reported in the Arctic. Our results indicate that upward transport of DMS, from the algal-rich bottom of first-year sea ice through the permeable sea ice, may represent an important pathway for this biogenic gas toward the atmosphere in ice-covered oceans in spring and summer.

scholarly journals Fatty acids and stable isotope signatures of first-year and multiyear sea ice in the Canadian High Arctic

Elem Sci Anth ◽  
2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Doreen Kohlbach ◽  
Steven W. Duerksen ◽  
Benjamin A. Lange ◽  
Joannie Charette ◽  
Anke Reppchen ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Sea Ice ◽  
Food Web ◽  
Relative Proportion ◽  
High Arctic ◽  
First Year ◽  
Biochemical Processes ◽  
Food Web Interactions ◽  
Stable Isotope Signatures ◽  
Critical Components

Ice algae are critical components to the lipid-driven Arctic marine food web, particularly early in the spring. As little is known about these communities in multiyear ice (MYI), we aimed to provide a baseline of fatty acid (FA) and stable isotope signatures of sea-ice communities in MYI from the Lincoln Sea and compare these biomarkers to first-year ice (FYI). Significant differences in the relative proportions of approximately 25% of the identified FAs and significantly higher nitrogen stable isotope values (δ15N) in bottom-ice samples of FYI (δ15N = 6.4 ± 0.7%) compared to MYI (δ15N = 5.0 ± 0.4%) reflect different community compositions in the two ice types. Yet, the relative proportion of diatom- and dinoflagellate-associated FAs, as well as their bulk and most of the FA-specific carbon stable isotope compositions (δ13C) were not significantly different between bottom FYI (bulk δ13C: –28.4% to –26.7%, FA average δ13C: –34.4% to –31.7%) and MYI (bulk δ13C: –27.6% to –27.2%, FA average δ13C: –33.6% to –31.9%), suggesting at least partly overlapping community structures and similar biochemical processes within the ice. Diatom-associated FAs contributed, on average, 28% and 25% to the total FA content of bottom FYI and MYI, respectively, indicating that diatoms play a central role in structuring sea-ice communities in the Lincoln Sea. The differences in FA signatures of FYI and MYI support the view that different ice types harbor different inhabitants and that the loss of Arctic MYI will impact complex food web interactions with ice-associated ecosystems. Comparable nutritional quality of FAs, however, as indicated by similar average levels of polyunsaturated FAs in bottom FYI (33%) and MYI (28%), could help to ensure growth and reproduction of ice-associated grazers despite the shift from a MYI to FYI-dominated sea-ice cover with ongoing climate warming.

Sea ice characteristics during the Weddell Sea expedition explored by geophysical and remote sensing methods

2020 ◽  
Author(s):  
Wolfgang Rack ◽  
Frazer Christie ◽  
Evelyn Dowdeswell ◽  
Julian Dowdeswell ◽  
Paul Wachter ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Sea Ice ◽  
Extended Period ◽  
Weddell Sea ◽  
Altimeter Data ◽  
First Year ◽  
Limited Information ◽  
Radar Images ◽  
Ice Floes ◽  
Remote Sensing Methods

<p>The 2019 Weddell Sea expedition provided a unique opportunity for geophysical and glaciological sea ice measurements in one of the least accessible regions of the Southern Ocean. Although the extent and area of sea ice is well known based on satellite measurements, the limited information on thickness does still hinder the calculation of trends trends in volume and mass. Sea ice thickness is therefore one of the missing key variables in the global cryosphere mass balance, and difficult logistics are a challenge for near synchronous satellite validation measurements. Another key variable in this context is snow on sea ice, as knowledge of snow is required to convert satellite-derived freeboard to thickness.</p><p>We measured the sea-ice morphology by a combination of on ice and remote sensing methods: near-synchronous temporal and spatial measurements from a drone equipped with a radar sensor and camera, manually-derived on-ice surveys and samples such as snow pits, snow-depth transects and drill holes, and a AUV with upward-looking multibeam sonars. We also deployed ice-drifter buoys on several ice floes which we used to provide floe drift over an extended period of time.</p><p>In this contribution we present the results of our observations in conjunction with a close sequence of high resolution satellite radar images (TerraSAR-X, Sentinel-1) and altimeter data (ICESat-2 and CryoSat-2) to characterise the sea ice conditions in the western Weddell Sea. We found a mixture of fragments of deformed first-year and multi-year sea-ice which was consolidated in larger ice floes. A thick snow cover frequently depressed the ice cover of the thinner first year ice below sea level. Satellite data allow to extend our findings in time to a larger area and to improve our information on sea ice over a larger region.</p>

scholarly journals Growth Rate and Salinity Profile of First-Year Sea Ice in the High Arctic

1981 ◽  
Vol 27 (96) ◽  
pp. 315-330 ◽  
Author(s):  
M. Nakawo ◽  
N. K Sinha
Keyword(s):  
Growth Rate ◽  
Sea Ice ◽  
Physical Properties ◽  
High Arctic ◽  
First Year ◽  
Baffin Island ◽  
Growth Season ◽  
Method Of Calculation ◽  
Salinity Profile ◽  
Snow Conditions

AbstractThis paper describes the growth of sea ice and the salinity profiles observed in Eclipse Sound near Pond Inlet, Baffin Island, Canada, during the winter of 1977–78. A numerical method of calculation has been developed to incorporate the variations in snow conditions and physical properties of ice and snow during the growth season. It is shown that the growth rate can be predicted reasonably well. It is also shown that the vertical salinity profile in the ice towards the end of the season, provides a record of previous climatological conditions. A dependence has been shown between the predicted growth rate and the measured salinity.

scholarly journals Snow microstructure on sea ice: Importance for remote sensing applications

2021 ◽  
Author(s):  
Amy R. Macfarlane ◽  
Stefanie Arndt ◽  
Ruzica Dadic ◽  
Carolina Gabarró ◽  
Bonnie Light ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Sea Ice ◽  
Remote Sensing Data ◽  
High Arctic ◽  
First Year ◽  
Sensing Data ◽  
Snow Properties ◽  
Multiyear Ice ◽  
Snow Samples

<p>Snow plays a key role in interpreting satellite remote sensing data from both active and passive sensors in the high Arctic and therefore impacts retrieved sea ice variables from these systems ( e.g., sea ice extent, thickness and age). Because there is high spatial and temporal variability in snow properties, this porous layer adds uncertainty to the interpretation of signals from spaceborne optical sensors, microwave radiometers, and radars (scatterometers, SAR, altimeters). We therefore need to improve our understanding of physical snow properties, including the snow specific surface area, snow wetness and the stratigraphy of the snowpack on different ages of sea ice in the high Arctic.</p><p>The MOSAiC expedition provided a unique opportunity to deploy equivalent remote sensing sensors in-situ on the sea ice similar to those mounted on satellite platforms. To aid in the interpretation of the in situ remote sensing data collected, we used a micro computed tomography (micro-CT) device. This instrument was installed on board the Polarstern and was used to evaluate geometric and physical snow properties of in-situ snow samples.  This allowed us to relate the snow samples directly to the data from the remote sensing instruments, with the goal of improving interpretation of satellite retrievals. Our data covers the full annual evolution of the snow cover properties on multiple ice types and ice topographies including level first-year (FYI), level multi-year ice (MYI) and ridges.</p><p>First analysis of the data reveals possible uncertainties in the retrieved remote sensing data products related to previously unknown seasonal processes in the snowpack. For example, the refrozen porous summer ice surface, known as surface scattering layer, caused the formation of a hard layer at the multiyear ice/snow interface in the winter months, leading to significant differences in the snow stratigraphy and remote sensing signals from first-year ice, which has not experienced summer melt, and multiyear ice. Furthermore, liquid water dominates the extreme coarsening of snow grains in the summer months and in winter the temporally large temperature gradients caused strong metamorphism, leading to brine inclusions in the snowpack and large depth hoar structures, all this significantly influences the signal response of remote sensing instruments.</p>

scholarly journals Observations of Sea Ice Melt from Operation IceBridge Imagery

2019 ◽  
Author(s):  
Nicholas C. Wright ◽  
Chris M. Polashenski ◽  
Scott T. McMichael ◽  
Ross A. Beyer
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
First Year ◽  
Ice Melt ◽  
Melt Pond ◽  
Ice Surface ◽  
Optical Images ◽  
Arctic Sea ◽  
Ice Floes ◽  
Multiyear Ice

Abstract. The summer albedo of Arctic sea ice is heavily dependent on the fraction and color of melt ponds that form on the ice surface. This work presents a new dataset of sea ice surface fractions along Operation IceBridge (OIB) flight tracks derived from the Digital Mapping System optical imagery set. This dataset was created by deploying version 2 of the Open Source Sea-ice Processing (OSSP) algorithm to NASA’s Advanced Supercomputing Pleiades System. These new surface fraction results are then analyzed to investigate the behavior of meltwater on first-year ice in comparison to multiyear ice. Observations herein show that first-year ice does not ubiquitously have a higher melt pond fraction than multiyear ice under the same forcing conditions, contrary to established knowledge in the sea ice community. We discover and document a larger possible spread of pond fractions on first year ice leading to both high and low pond coverage, in contrast to the uniform melt evolution that has been previously observed on multiyear ice floes. We also present a selection of optical images that captures both the typical and atypical ice types, as observed from the OIB dataset. We hope to demonstrate the power of this new dataset and to encourage future collaborative efforts to utilize the OIB data to explore the behavior of melt pond formation Arctic sea ice.

scholarly journals The Borehole Jack—Is It a Useful Arctic Tool?

1987 ◽  
Vol 109 (4) ◽  
pp. 391-397 ◽  
Author(s):  
Nirmal K. Sinha
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Melting Point ◽  
Sea Ice ◽  
High Arctic ◽  
Test System ◽  
Simultaneous Recording ◽  
First Year ◽  
Test Procedures ◽  
Operational Conditions

As the working temperatures in ice are very close to its melting point, it behaves viscoelastically and experiences what is commonly known as high temperature embrittlement. Its mechanical properties are rate sensitive and analysis must include load and displacement history. Borehole jack tests can be improved by the use of an electrohydraulic pump in conjunction with simultaneous recording of pressure and diametral displacement as a function of time. These small but significant modifications in the test procedures permit analysis of the response of a borehole jack test system under operational conditions in the High Arctic in first-year and multi-year sea ice.

Mercury uptake within an ice algal community during the spring bloom in first-year Arctic sea ice

2013 ◽  
Vol 118 (9) ◽  
pp. 4746-4754 ◽  
Author(s):  
Alexis Burt ◽  
Feiyue Wang ◽  
Monika Pućko ◽  
Christopher-John Mundy ◽  
Michel Gosselin ◽  
...  
Keyword(s):  
Sea Ice ◽  
Spring Bloom ◽  
Arctic Sea Ice ◽  
Algal Community ◽  
First Year ◽  
Mercury Uptake ◽  
Arctic Sea

scholarly journals Observations of sea ice melt from Operation IceBridge imagery

2020 ◽  
Vol 14 (10) ◽  
pp. 3523-3536
Author(s):  
Nicholas C. Wright ◽  
Chris M. Polashenski ◽  
Scott T. McMichael ◽  
Ross A. Beyer
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
First Year ◽  
Ice Melt ◽  
Melt Pond ◽  
Ice Surface ◽  
Optical Images ◽  
Arctic Sea ◽  
Ice Floes ◽  
Multiyear Ice

Abstract. The summer albedo of Arctic sea ice is heavily dependent on the fraction and color of melt ponds that form on the ice surface. This work presents a new dataset of sea ice surface fractions along Operation IceBridge (OIB) flight tracks derived from the Digital Mapping System optical imagery set. This dataset was created by deploying version 2 of the Open Source Sea-ice Processing (OSSP) algorithm to NASA's Advanced Supercomputing Pleiades System. These new surface fraction results are then analyzed to investigate the behavior of meltwater on first-year ice in comparison to multiyear ice. Observations herein show that first-year ice does not ubiquitously have a higher melt pond fraction than multiyear ice under the same forcing conditions, contrary to established knowledge in the sea ice community. We discover and document a larger possible spread of pond fractions on first-year ice leading to both high and low pond coverage, in contrast to the uniform melt evolution that has been previously observed on multiyear ice floes. We also present a selection of optical images that capture both the typical and atypical ice types, as observed from the OIB dataset. The derived OIB data presented here will be key to explore the behavior of melt pond formation Arctic sea ice.

scholarly journals Growth Rate and Salinity Profile of First-Year Sea Ice in the High Arctic

1981 ◽  
Vol 27 (96) ◽  
pp. 315-330 ◽  
Author(s):  
M. Nakawo ◽  
N. K Sinha
Keyword(s):  
Growth Rate ◽  
Sea Ice ◽  
Physical Properties ◽  
High Arctic ◽  
First Year ◽  
Baffin Island ◽  
Growth Season ◽  
Method Of Calculation ◽  
Salinity Profile ◽  
Snow Conditions

AbstractThis paper describes the growth of sea ice and the salinity profiles observed in Eclipse Sound near Pond Inlet, Baffin Island, Canada, during the winter of 1977–78. A numerical method of calculation has been developed to incorporate the variations in snow conditions and physical properties of ice and snow during the growth season. It is shown that the growth rate can be predicted reasonably well. It is also shown that the vertical salinity profile in the ice towards the end of the season, provides a record of previous climatological conditions. A dependence has been shown between the predicted growth rate and the measured salinity.

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