Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Authors:Jones; Elizabeth M., Hoppema, Mario, Bakker, Karel, de Baar, Hein J.W. Pages: 575 - 595 Abstract: The waters along the West Antarctic Peninsula (WAP) have experienced warming and increased freshwater inputs from melting sea ice and glaciers in recent decades. Challenges exist in understanding the consequences of these changes on the inorganic carbon system in this ecologically important and highly productive ecosystem. Distributions of dissolved inorganic carbon (CT), total alkalinity (AT) and nutrients revealed key physical, biological and biogeochemical controls of the calcium carbonate saturation state (Ωaragonite) in different water masses across the WAP shelf during the summer. Biological production in spring and summer dominated changes in surface water Ωaragonite (ΔΩaragonite up to +1.39; ~90%) relative to underlying Winter Water. Sea-ice and glacial meltwater constituted a minor source of AT that increased surface water Ωaragonite (ΔΩaragonite up to +0.07; ~13%). Remineralization of organic matter and an influx of carbon-rich brines led to cross-shelf decreases in Ωaragonite in Winter Water and Circumpolar Deep Water. A strong biological carbon pump over the shelf created Ωaragonite oversaturation in surface waters and suppression of Ωaragonite in subsurface waters. Undersaturation of aragonite occurred at < ~1000 m. Ongoing changes along the WAP will impact the biologically driven and meltwater-driven processes that influence the vulnerability of shelf waters to calcium carbonate undersaturation in the future. PubDate: 2021-10-28 DOI: 10.1017/S0954102021000456
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Authors:Câmara; Paulo E.A.S., De Souza, Láuren M.D., Pinto, Otávio Henrique Bezerra, Convey, Peter, Amorim, Eduardo T., Carvalho-Silva, Micheline, Rosa, Luiz Henrique Pages: 596 - 604 Abstract: Antarctic lakes have generally simple periphyton communities when compared with those of lower latitudes. To date, assessment of microbial diversity in Antarctica has relied heavily on traditional direct observation and cultivation methods. In this study, sterilized cotton baits were left submerged for two years in two lakes on King George Island and Deception Island, South Shetland Islands (Maritime Antarctic), followed by assessment of diversity by metabarcoding using high-throughput sequencing. DNA sequences of 44 taxa belonging to four kingdoms and seven phyla were found. Thirty-six taxa were detected in Hennequin Lake on King George Island and 20 taxa were detected in Soto Lake on Deception Island. However, no significant difference in species composition was detected between the two assemblages (Shannon index). Our data suggest that metabarcoding provides a suitable method for the assessment of periphyton biodiversity in oligotrophic Antarctic lakes. PubDate: 2021-09-20 DOI: 10.1017/S0954102021000316
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Authors:Lukashanets; Dzmitry A., Convey, Peter, Borodin, Oleg I., Miamin, Vladislav Ye., Hihiniak, Yury H., Gaydashov, Alexey A., Yatsyna, Aleksander P., Vezhnavets, Vasil V., Maysak, Natallia N., Shendrik, Tatyana V. Pages: 605 - 623 Abstract: Knowledge of the biodiversity of the Thala Hills oasis (Enderby Land, East Antarctica) is very limited. Here, we integrate all information available since 1962, when the Russian ‘Molodyozhnaya’ station was established in the western part of the oasis. The published data on local eukaryote diversity (lichens, embryophytes, metazoans) include records of 90 species. Since 2008, Belarusian Antarctic Expedition researchers have worked in the eastern part of the oasis, accessible from the Belarusian station ‘Vechernyaya Mount'. This research revealed 95 species, including 44 species not recorded in the earlier published literature. The level of available information is uneven across major taxa. Lichens are the better-known group, with 51 species recorded in total, including 13 species recently recorded for the first time in the oasis. New records were also obtained for rotifers. Thala Hills biodiversity is consistent with wider patterns of Antarctic biogeography, with a high proportion of regionally endemic species (especially metazoans), the occurrence of both endemic and bipolar species of lichens and generally low numbers of cosmopolitan species (largely limited to aquatic rotifers, with the caveat that up-to-date taxonomic studies are required). The lack of data on marine macrobenthos, soil nematodes and terrestrial rotifers emphasizes the need for studies focusing on these groups. PubDate: 2021-10-26 DOI: 10.1017/S0954102021000328
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Authors:Bhushan; Brij, Tanwar, Himanshi, Eslavath, Malleswara Rao, Singh, Shashi Bala, Kumar, Bhuvnesh, Ganju, Lilly Pages: 624 - 632 Abstract: Mucosal immunity of Indian Antarctic personnel was analysed during the 34th Indian Scientific Expedition to Antarctica (ISEA) by ship voyage. Serum and salivary IgA, IgA1 and IgA2 levels along with salivary cortisol and TGF-β were quantified by enzyme-linked immunosorbent assay. Samples were collected at three different time points (T1, T2 and T3) during the expedition. Serum and salivary IgA, IgA1 and IgA2 concentrations incrementally increased towards the end of the expedition as compared to the beginning of the expedition. Salivary IgA and TGF-β levels were significantly altered during the expedition. Levels of IgA1 (P = 0.0007) and IgA2 (P = 0.0135) increased significantly at T3 as compared to T1. Additionally, significant changes in serum IgA were observed, with peak levels at T3 (P = 0.0015) and T2 (P < 0.001). However, the level of serum IgA2 was also significantly altered at T3 (P < 0.05) and T2 (P = 0.0006) in comparison with T1. The exact cause of the changes in serum and salivary IgA, IgA1, IgA2 and TGF-β levels during the summer expedition are unknown; however, the changes are evident in mucosal immunity. PubDate: 2021-09-08 DOI: 10.1017/S0954102021000407
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Authors:Peralta-Figueroa; Christian, Martínez-Oyanedel, José, Bunster, Marta, González-Rocha, Gerardo Pages: 633 - 644 Abstract: Proteases are widely used in industrial processes, and the discovery of new, more kinetically efficient proteases can have a positive impact on industry. Enzymes from Antarctic microorganisms exhibit cold-adaptive properties, making them useful in biotechnology. The cold and harsh environment of Antarctica makes it a valuable source for new biotechnologically related enzymes. In this study, we characterized two cold-adapted proteases purified from Pseudoalteromonas issachenkonii P14M1-4 and Flavobacterium frigidimaris ANT34-7, isolated from King George Island, Antarctica, and compared these with proteases from the non-cold-adapted bacteria Bacillus licheniformis and Geobacillus stearothermophilus. The best temperature growing conditions were used for protease purification and characterization. The protease from P. issachenkonii P14M1-4 was identified as a 40–43 kDa metal-dependent subtilisin-like serine protease and the protease from F. frigidimaris ANT34-7 was identified as a 28 kDa metalloprotease. The enzymes showed an optimum temperature of between 35°C and 40°C and an optimum pH in the neutral to alkaline range. Their activation energies, catalytic constants and growth capacities at different temperatures categorize them as cold-adapted enzymes. We conclude that the characteristics exhibited by these proteases make them useful for biotechnological purposes requiring high activity at low temperatures. Moreover, to the best of our knowledge, this is the first characterization of a cold-adapted protease from F. frigidimaris. PubDate: 2021-10-20 DOI: 10.1017/S0954102021000468
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Authors:Dang; Nguk-Ling, Chu, Wan-Loy, Yap, Kok-Seng Ivan, Kok, Yih-Yih, Phang, Siew-Moi, Chan, Kok-Keong, Convey, Peter Pages: 645 - 659 Abstract: Human- and animal-impacted sites in Antarctica can be contaminated with heavy metals, as well as areas influenced by underlying geology and naturally occurring minerals. The present study examined the relationship between heavy metal presence and soil microalgal occurrence across a range of human-impacted and undisturbed locations on Signy Island. Microalgae were identified based on cultures that developed after inoculation into an enriched medium. Twenty-nine microalgae representing Cyanobacteria, Bacillariophyta, Chlorophyta and Tribophyta were identified. High levels of As, Ca, Cd, Cu and Zn were detected in Gourlay Peninsula and North Point, both locations hosting dense penguin rookeries. Samples from Berntsen Point, the location of most intense human activity both today and historically, contained high levels of Pb. The contamination factor and pollution load index confirmed that the former locations were polluted by Cd, Cu and Zn, with these being of marine biogenic origin. Variation in the microalgal community was significantly correlated with concentrations of Mn, Ca, Mg, Fe, Zn, Cd, Co, Cr and Cu. However, the overall proportion of the total variation contributed by all metals was low (16.11%). Other factors not measured in this study are likely to underlie the majority of the observed variation in microalgal community composition between sampling locations. PubDate: 2021-09-13 DOI: 10.1017/S0954102021000390
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Authors:Carvallo; Claire, Godoy, Nathaly, Aguilar, Bertha, Egas, Claudia, Fuentealba, Raúl, Préndez, Margarita Pages: 660 - 673 Abstract: Antarctica is a natural research laboratory thanks to its unique climate, geography, flora and fauna. The conservation of Antarctica's environment is monitored through the Madrid Protocol; however, there are local pollution problems associated with human activities such as research and tourism; in particular, there are negative impacts on air quality from the use of fossil fuels. In this work, we studied for the first time the magnetic and elemental characteristics of the lichen Usnea aurantiaco-atra (Jacq.) Bory collected during different years and from various sites in King George Island, Antarctic Peninsula, as well as some samples of its supporting substrate, for long-term monitoring of atmospheric pollution. Several anthropogenic elements (Ni, Pb, Mo, Cd and Zn) have been identified on sites close to human activities, but also on sites far from them. We found that magnetic proxies from U. aurantiaco-atra samples show a spatial correlation with human influence (scientific bases or airstrips). We observed a correlation between magnetic parameters and Ni and, to a lesser extent, with Cr, Co, V and Ag. The results suggest that by using these magnetic and elemental techniques it is possible to implement monitoring with the lichen U. aurantiaco-atra as a bioindicator for some elements of anthropogenic origin. PubDate: 2021-10-25 DOI: 10.1017/S0954102021000419
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Authors:Kwon; Hataek, Kim, Seong-Joong, Kim, Sang-Woo, Kim, Sinu Pages: 674 - 684 Abstract: The topographical effect on a strong wind event that occurred on 7 January 2013 at King Sejong Station (KSJ), Antarctica, was investigated using the Polar Weather Research and Forecasting (WRF) model. Numerical experiments applying three different terrain heights of the Antarctic Peninsula (AP) were performed to quantitatively estimate the topographical effect on the selected strong wind event. The experiment employing original AP topography successfully represented the observed features in the strong wind event, both in terms of peak wind speed (by ~94%; ~19.7 m/s) and abrupt transitions of wind speed. In contrast, the experiment with a flattened terrain height significantly underestimated the peak wind speeds (by ~51%; ~10.4 m/s) of the observations. An absence of AP topography failed to simulate both a strong discontinuity of sea-level pressure fields around the east coast of the AP and a strong south-easterly wind over the AP. As a result, the observed downslope windstorm, driven by a flow overriding a barrier, was not formed at the western side of the AP, resulting in no further enhancement of the wind at KSJ. This result demonstrates that the topography of the AP played a critical role in driving the strong wind event at KSJ on 7 January 2013, accounting for ~50% of the total wind speed. PubDate: 2021-10-20 DOI: 10.1017/S0954102021000444
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