Seasonal development of algal biomass in snow-covered fast ice and the underlying platelet layer in the Weddell Sea, Antarctica

The seasonal changes of the nutrient regime and the development of algal communities in snow-covered fast ice and the underlying platelet layer was investigated in the eastern Weddell Sea during autumn, winter, and spring 1995. In the upper sea ice, an autumnal diatom community became enclosed during subsequent ice growth in winter, declined, and was replaced by a flagellate dominated community in spring. In this layer, nitrate was completely exhausted at the end of spring, although nutrients had been partly regenerated in early spring. The progressive congelation of platelet ice contributed significantly to sea ice growth thus influencing algal inoculation of the sea ice bottom. Biomass, present in the uppermost section of the platelet layer, could be found in the sea ice bottom after this section congealed to solid ice. After incorporation, species composition changed from larger and chain-forming species to species of smaller cell size. Concurrently, net growth rate slowed down from 0.07 day−1 within the platelet layer to 0.03 day−1 within the sea ice. Despite a thick snow cover of more than 20 cm, maximum biomass yield was 210 mg chl a m−2 in the platelet layer and 40 mg chl a m−2 in the sea ice respectively, while 95% of the latter was located within consolidated platelet ice. Total fast ice biomass observed here is significantly lower than that observed in snow-free fast ice of the Ross Sea, but because snow cover of the southern Weddell Sea is representative of most fast ice areas in the Antarctic, the data presented here are of general value.

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Turbulent heat transfer as a control of platelet ice growth in supercooled under-ice ocean boundary layers

Ocean Science ◽

10.5194/os-12-507-2016 ◽

2016 ◽

Vol 12 (2) ◽

pp. 507-515 ◽

Cited By ~ 1

Author(s):

Miles G. McPhee ◽

Craig L. Stevens ◽

Inga J. Smith ◽

Natalie J. Robinson

Keyword(s):

Heat Transfer ◽

Sea Ice ◽

Turbulent Heat Transfer ◽

Late Winter ◽

Turbulent Heat ◽

Ice Shelves ◽

Ice Growth ◽

Turbulent Heat Exchange ◽

Fast Ice ◽

Platelet Ice

Abstract. Late winter measurements of turbulent quantities in tidally modulated flow under land-fast sea ice near the Erebus Glacier Tongue, McMurdo Sound, Antarctica, identified processes that influence growth at the interface of an ice surface in contact with supercooled seawater. The data show that turbulent heat exchange at the ocean–ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing, analogous to similar results for moderate melting rates in seawater above freezing. Platelet ice growth appears to increase the hydraulic roughness (drag) of fast ice compared with undeformed fast ice without platelets. Platelet growth in supercooled water under thick ice appears to be rate-limited by turbulent heat transfer and that this is a significant factor to be considered in mass transfer at the underside of ice shelves and sea ice in the vicinity of ice shelves.

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Estimation of Thin Ice Thickness and Detection of Fast Ice from SSM/I Data in the Antarctic Ocean

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech2113.1 ◽

2007 ◽

Vol 24 (10) ◽

pp. 1757-1772 ◽

Cited By ~ 77

Author(s):

Takeshi Tamura ◽

Kay I. Ohshima ◽

Thorsten Markus ◽

Donald J. Cavalieri ◽

Sohey Nihashi ◽

...

Keyword(s):

Sea Ice ◽

Ross Sea ◽

Weddell Sea ◽

Ice Thickness ◽

Coastal Current ◽

Antarctic Ocean ◽

Coastal Polynya ◽

Fast Ice ◽

Ice Production ◽

The Antarctic

Abstract Antarctic coastal polynyas are important areas of high sea ice production and dense water formation, and thus their detection including an estimate of thin ice thickness is essential. In this paper, the authors propose an algorithm that estimates thin ice thickness and detects fast ice using Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) data in the Antarctic Ocean. Detection and estimation of sea ice thicknesses of <0.2 m are based on the SSM/I 85- and 37-GHz polarization ratios (PR85 and PR37) through a comparison with sea ice thicknesses estimated from the Advanced Very High Resolution Radiometer (AVHRR) data. The exclusion of data affected by atmospheric water vapor is discussed. Because thin ice and fast ice (specifically ice shelves, glacier tongues, icebergs, and landfast ice) have similar PR signatures, a scheme was developed to separate these two surface types before the application of the thin ice algorithm to coastal polynyas. The probability that the algorithm correctly distinguishes thin ice from thick ice and from fast ice is ∼95%, relative to the ice thicknesses estimated from AVHRR. Although the standard deviation of the difference between the thin ice thicknesses estimated from the SSM/I algorithm and AVHRR is ∼0.05 m and thus not small, the estimated ice thicknesses from the microwave algorithm appear to have small biases and the accuracies are independent of region and season. A distribution map of thin ice occurrences derived from the SSM/I algorithm represents the Ross Sea coastal polynya being by far the largest among the Antarctic coastal polynyas; the Weddell Sea coastal polynyas are much smaller. Along the coast of East Antarctica, coastal polynyas frequently form on the western side of peninsulas and glacier tongues, downstream of the Antarctic Coastal Current.

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Physical and biological properties of early winter Antarctic sea ice in the Ross Sea

Annals of Glaciology ◽

10.1017/aog.2020.43 ◽

2020 ◽

pp. 1-19

Author(s):

Jean-Louis Tison ◽

Ted Maksym ◽

Alexander D. Fraser ◽

Matthew Corkill ◽

Noriaki Kimura ◽

...

Keyword(s):

Sea Ice ◽

Ross Sea ◽

Thickness Distribution ◽

Biological Properties ◽

Weddell Sea ◽

Algal Community ◽

Early Winter ◽

Ice Growth ◽

Antarctic Sea Ice ◽

Spatial Differences

Abstract This work presents the results of physical and biological investigations at 27 biogeochemical stations of early winter sea ice in the Ross Sea during the 2017 PIPERS cruise. Only two similar cruises occurred in the past, in 1995 and 1998. The year 2017 was a specific year, in that ice growth in the Central Ross Sea was considerably delayed, compared to previous years. These conditions resulted in lower ice thicknesses and Chl-a burdens, as compared to those observed during the previous cruises. It also resulted in a different structure of the sympagic algal community, unusually dominated by Phaeocystis rather than diatoms. Compared to autumn-winter sea ice in the Weddell Sea (AWECS cruise), the 2017 Ross Sea pack ice displayed similar thickness distribution, but much lower snow cover and therefore nearly no flooding conditions. It is shown that contrasted dynamics of autumnal-winter sea-ice growth between the Weddell Sea and the Ross Sea impacted the development of the sympagic community. Mean/median ice Chl-a concentrations were 3–5 times lower at PIPERS, and the community status there appeared to be more mature (decaying?), based on Phaeopigments/Chl-a ratios. These contrasts are discussed in the light of temporal and spatial differences between the two cruises.

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Coastal fast ice in the Shokalski Strait

Journal Ice and Snow ◽

10.15356/2076-6734-2016-4-525-532 ◽

2016 ◽

Vol 56 (4) ◽

pp. 525-532 ◽

Cited By ~ 1

Author(s):

V. A. Borodkin ◽

A. P. Makshtas ◽

P. V. Bogorodsky

Keyword(s):

Sea Ice ◽

Ice Cover ◽

Early Spring ◽

The Arctic ◽

Similar Process ◽

Research Station ◽

Arctic Seas ◽

Sea Ice Thickness ◽

Ice Growth ◽

Fast Ice

Field investigations of coastal fast ice near the research station Ice Base on the «Cape Baranova», carried out in 2013–2014, made possible to reveal a number of characteristics of the sea ice cover formation. It has been shown that during winter and early spring the sea ice thickness, being formed due to intensive snow drift and caused by that flooding of the ice cover just near the coast of the Bolshevik Island, substantially grows at its upper boundary, that is typical for the Antarctic seas. At the same time, similar process of the ice growth at a relatively short distance from the coast shows all features characteristic for the ice cover in the Arctic seas, and that is well reproduced by the conceptual numerical sea ice model. Thus, the region of the Ice Base «Cape Baranova» represents a natural laboratory for studying the processes of the sea ice formation in both, the Arctic and Antarctic seas under condition of the same atmospheric forcing. Transformation of the fast ice structure during the summer time is described. Results of the investigations has demonstrated that despite the radical changes in the structure thicknesses of the fast ice remained almost unchanged due to the ice growth on the bottom boundary of the ice cover until a destruction of it in August.

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Turbulent heat transfer as a control of platelet ice growth in supercool under-ice ocean boundary-layers

Ocean Science Discussions ◽

10.5194/osd-12-2807-2015 ◽

2015 ◽

Vol 12 (6) ◽

pp. 2807-2829 ◽

Cited By ~ 1

Author(s):

M. G. McPhee ◽

C. L. Stevens ◽

I. J. Smith ◽

N. J. Robinson

Keyword(s):

Heat Transfer ◽

Sea Ice ◽

Turbulent Heat Transfer ◽

Late Winter ◽

Turbulent Heat ◽

Ice Shelves ◽

Ice Growth ◽

Turbulent Heat Exchange ◽

Fast Ice ◽

Platelet Ice

Abstract. Late winter measurements of turbulent quantities in tidally modulated flow under land-fast sea ice near the Erebus Glacier Tongue, McMurdo Sound, identified processes that influence growth at the interface of an ice surface in contact with supercool seawater. The data suggest that turbulent heat exchange at the ocean-ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing, analogous to similar results for moderate melting rates in seawater above freezing. Platelet ice growth appears to increase the hydraulic roughness (drag) of fast ice compared with undeformed fast ice without platelets. We hypothesize that platelet growth in supercool water under thick ice is rate-limited by turbulent heat transfer and that this is a significant factor to be considered in mass transfer at the under-side of ice shelves and sea ice in the vicinity of ice shelves.

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Antarctic sea ice variability and trends, 1979–2010

The Cryosphere Discussions ◽

10.5194/tcd-6-931-2012 ◽

2012 ◽

Vol 6 (2) ◽

pp. 931-956 ◽

Cited By ~ 16

Author(s):

C. L. Parkinson ◽

D. J. Cavalieri

Keyword(s):

Indian Ocean ◽

Sea Ice ◽

Ross Sea ◽

Ice Cover ◽

Weddell Sea ◽

The Arctic ◽

Future Research ◽

Positive Trend ◽

Antarctic Sea Ice ◽

Ice Coverage

Abstract. In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

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Thraustochytrid protists in Antarctic fast ice?

Antarctic Science ◽

10.1017/s0954102093000379 ◽

1993 ◽

Vol 5 (3) ◽

pp. 279-280 ◽

Cited By ~ 13

Author(s):

Franz Riemann ◽

Karsten Schaumann

Keyword(s):

Sea Ice ◽

Ice Core ◽

Short Note ◽

Weddell Sea ◽

Lower Section ◽

Fast Ice ◽

Arctic Ice ◽

Pennate Diatoms

Sea ice provides a habitat for a conspicuous and productive assemblage of autotrophic microalgae and for heterotrophs ranging from bacteria to vertebrates (Horner 1990, Garrison 1991). With the exception of a reference to chytridiaceous fungi that were found infecting Arctic ice diatoms (Horner 1977) and a note in a cruise report (Schnack-Schiel 1987, p. 153), it appears that fungi and similar organisms have until now not been mentioned as members of the heterotrophic sea ice community. In the present short note we report on the abundant occurrence of apparently thraustochytrid fungus-like protists associated with mucilage tubes of pennate diatoms, encountered in the lower section of a fast ice core drilled close to the southern shelf ice margin of the Weddell Sea.

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Land-fast ice microalgal and phytoplanktonic communities (Adélie Land, Antarctica) in relation to environmental factors during ice break-up

Antarctic Science ◽

10.1017/s0954102003001378 ◽

2003 ◽

Vol 15 (3) ◽

pp. 353-364 ◽

Cited By ~ 19

Author(s):

C. RIAUX-GOBIN ◽

M. POULIN ◽

R. PRODON ◽

P. TREGUER

Keyword(s):

Sea Ice ◽

Early Spring ◽

Ice Melt ◽

Fast Ice ◽

Maximum Cell ◽

Cell Densities ◽

Ice Water ◽

Water Species ◽

Very High ◽

Pennate Diatoms

Annual land-fast ice, particularly an unconsolidated layer or “platelet ice-like” layer (PLI), was sampled in spring 1995 to study the spatial and short-term variations of ice-associated diatoms. Under-ice water, a lead and small polynyas were also sampled. Along a 7 km seaward transect a geographical gradient was evident, with some rare diatom species present only in the offshore PLI, whereas others (mainly pennate diatoms) were ubiquitous. The dense microphytic PLI community as well as the phytoplankton was diatom-dominated, but, within these two communities, marked differences appeared. First, the sea-ice communities (PLI and solid bottom ice) were moderately diverse (36 species), mostly composed of pennate diatoms, of which many were chain forming or tube-dwelling. Dominant taxa were Navicula glaciei, Berkeleya adeliensis, Nitzschia stellata, Amphiprora kufferathii and Nitzschia lecointei. Some differences in the distribution of the most dominant species appeared within the bottom ice and the PLI, attesting to differences in the origin or/and growing capability of these diatoms in these two ice compartments. Under-ice water species composition was mixed with sea-ice communities only on the most coastal sites and during ice melt. Maximum cell numbers were mostly noticed in the PLI, reaching up to 1010 cells l−1 and very high Chl a concentrations (exceptionally up to 9.8 mg Chl a l−1 or 1.9 g Chl a m−2, from a 10 to 20 cm thick PLI layer, close to the continent). Secondly, the phytoplankton in the lead and small polynyas had a low diversity, very low standing stocks (on an average 0.69 μg Chl a l−1) and cell densities (2 × 104 cells l−1). Some species from the polynyas were similar to those of the PLI, such as Navicula glaciei, but others were typically planktonic, such as Chaetoceros cf. neglectus. The presence of encysted cells (Chaetoceros and Chrysophytes) was also noticeable in the polynya water. In early spring no seeding process was obvious from the PLI to polynya water. A comparison with similar fast-ice diatom communities in other parts of coastal Antarctica, is presented.

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