Czech Polar Reports

Occurrence and group size of seals in the Western Antarctica: Results from the 2023 VII Turkish Antarctic Research Expedition

Mustafa Sözen, Nastassia Uluduz — Sun, 11 Jan 2026 00:00:00 +0100

Antarctica offers a unique opportunity to study climate-related changes and ecological responses due to its remoteness and relatively undisturbed ecosystems. Pinnipeds, which are among the top predators in the Southern Ocean, are important bioindicators of environmental conditions. This study presents data on the distribution, species composition, and group sizes of pinnipeds observed during the VII Turkish Antarctic Research Expedition along the Western Antarctic Peninsula (WAP) in January–February 2023. The observations were conducted both from the research vessel BIO Hespérides and during land-based surveys at nine sites located in the islands off the Danco and Graham Coasts, at the north side of Marguerite Bay, in South Shetland Islands and Trinity Peninsula. A total of 70 sightings were recorded, including five pinniped species from the Phocidae and Otariidae families: southern elephant seals (Mirounga leonina), Weddell seals (Leptonychotes weddellii), leopard seals (Hydrurga leptonyx), crabeater seals (Lobodon carcinophaga), and Antarctic fur seals (Arctocephalus gazella). No Ross seals (Ommatophoca rossii) were sighted. Southern elephant seals sightings (n = 40) were the most frequently recorded, especially in the northern part of the study area, with one group comprising up to 250 individuals. Weddell seals (n = 16) were mostly sighted on the sea ice near Adelaide Island, while Antarctic fur seals (n = 8) were observed both on land and at sea, with one unusually large aggregation (approximately 1,000 individuals). Leopard seals (n = 3) and crabeater seals (n = 2) were observed in small numbers, mostly as solitary individuals or in small groups. These results contribute to the baseline knowledge of pinniped distribution patterns along the WAP and provide insights into regional population structures during the austral summer. The data are important for future ecological monitoring and understanding of species-specific responses to environmental changes in Antarctic ecosystems.

Micromorphological features of organo-mineral interactions in soils and soil-like bodies of Thala Hills, East Antarctica

Ivan Alekseev, Elena Grek — Wed, 14 Jan 2026 00:00:00 +0100

Ice-free regions (oases) in East Antarctica have been recognized for their diverse environmental conditions of soil formation. Understanding the biogenic-abiogenic interactions, composition and dynamics of soil organic matter can provide insights into the resilience of Antarctic ecosystems in the face of environmental changes. Therefore, this study is aimed at the investigation of micromorphological features, biogeochemical properties and composition of soil organic matter across various scales in the soil and soil-like bodies of Thala Hills, East Antarctica. The examined soils are typically characterized by shallow profiles, predominantly coarse textures, slightly acidic to nearly neutral pH levels, and very low organic carbon content. Soil horizons studied differed by content of total organic carbon (from 0.42% in the sub-surface horizons to 13.68% in the topsoil Histic horizon in a wind shelter) and nitrogen (from 0.025% to 1.89%). Organomineral interactions are primarily observed in the form of biofilms, which predominantly develop in wind-sheltered areas and rock cavities. Micromorphological analyses revealed a predominance of primary materials, which are significantly modified by cryogenic processes (seen by vertical mineral alignment, cracks, and numerous packing voids) and physical weathering, with minimal influence from chemical weathering. Microscopic examination of soil thin sections indicated that the microfabric of these soils is predominantly composed of coarse detrital skeleton with abundant voids, while soils generally exhibit a low proportion of fine earth material.

Antiviral activity of Colobanthus quitensis (Kunth) Bartl. natural plant extract against transmissible gastroenteritis coronavirus in vitro

Sun, 11 Jan 2026 00:00:00 +0100

The primary goal of our study was to investigate the antiviral potential of natural extract of unique aboriginal Antarctic plant Colobanthus quitensis. The aqueous-ethanolic extract was assessed in vitro using MDСK (Madin-Darby Canine Kidney) and PEK (Porcine Embryonic Kidney) cell cultures, challenged with Porcine Coronavirus (TGEV). The observed antiviral properties were juxtaposed with those of synthetic flavonoid compounds, namely apigenin and luteolin. Ultimately, the data show that C. quitensis extracts exhibit in vitro potent antiviral activity against TGEV coronavirus. The composition of natural C. quitensis extracts was investigated using MALDI mass spectrome-try method.

Psychrotolerant enterobacters inhabiting the gut of Antarctic fishes of the family Nototheniidae and description of Enterobacter hoffmannii subsp. nototheniae subsp. nov.

Sun, 11 Jan 2026 00:00:00 +0100

The gut microbiota of four Antarctic marine fish species – Notothenia coriiceps, Trematomus bernacchii, Trematomus hansoni, and Trematomus newnesi – were analysed, with a particular focus on the members of the Enterobacter cloacae complex. Nineteen isolated strains were characterised by rep-PCR, automated ribotyping, extended phenotyping, and MALDI-TOF MS analysis. Fingerprinting methods grouped the psychrotolerant isolates into two distinct groups, representing the dominant enteric bacteria in the gut contents of these fish. Following their preliminary identification as members of the Enterobacter cloacae complex, additional phylogenetic analyses were conducted using the 16S rRNA and rpoB genes, as well as fatty acid analysis and whole-genome sequencing of two representatives selected based on their fingerprints. All results indicated that the analysed group represents a new autochthonous Enterobacter taxon inhabiting the gut of fish of the family Nototheniidae. Based on average nucleotide identity (ANI) and in silico DNA–DNA hybridization (dDDH) values, the “Enterobacter hoffmannii”, the effectively published but non-valid name, was the most closely related species to representatives of both groups of isolates from the gut of the above-specified notothenioid fish. The name Enterobacter hoffmannii subsp. nototheniae subsp. nov. is proposed, with the type strain P5473^T (= CCM 8629^T = LMG 34031^T), for isolates of Group 1. At the same time, the name Enterobacter hoffmannii subsp. hoffmannii subsp. nov. is suggested for isolates of Group 2, with the existing type strain DSM 14563^T = LMG 30171^T.

Limitation of visibility on the coast of the Kara Sea in the context of modern climate change

Sun, 11 Jan 2026 00:00:00 +0100

An analysis of standard meteorological observations of horizontal visibility was performed, based on instrumental and visual observations at two Russian meteorological stations located on the southern coast of the Kara Sea. Horizontal visibility is an important navigation criterion for choosing safe routes and speeds along the Northern Sea Route. A decrease in horizontal visibility to less than 50 m is a dangerous weather event. The study of the conditions for the occurrence of such a dangerous phenomenon has become especially relevant when using giant ice-class tankers, the length of which reaches 300 m. The analysis showed that the frequency (probability) of unfavorable conditions for horizontal visibility has a pronounced seasonal variation. A relationship was found between the increase in frequency and changing climatic conditions, namely an increase in frequency against the background of modern global warming which is expressed both in a steady increase in surface air temperature in all seasons of the year and in a reduction of sea ice cover in the summer.

Phytomass and organic carbon stocks in the mountain tundra communities of the Khibiny Mountains, Murmansk Region, Russia

Sun, 11 Jan 2026 00:00:00 +0100

This article presents the results of a field-measured monitoring study on the structure and productivity of two widespread community types within the mountain tundra belt of the Subarctic (Kola Peninsula, Khibiny Mountains). The data cover the period 2000 to 2023, during which the mean annual air temperature increased by 2.2°C. In 2023, the dwarf shrub community had an average aboveground phytomass of 908 g m^-2 and an annual production of 128 g m^-2, values 1.5–2 times higher than in the lichen community. The composition of aboveground phytomass was as follows - dwarf shrub community: 72% dwarf shrubs, 10% mosses, 18% lichens; lichen community: 32% dwarf shrubs, 6% mosses, 62% lichens. In the dwarf shrub community during the past two decades (2000–2023), the contribution of dwarf shrubs to the aboveground phytomass remained unchanged. However, a compositional change occurred: the proportion of evergreen dwarf shrubs nearly doubled, the moss component increased fivefold, while the lichen fraction decreased by a factor of 1.5. Aboveground phytomass increased by 22%, whereas annual production showed a slight decrease of 7%. The aboveground phytomass of the lichen community decreased by 15% over a twenty-year period. Its structural composition also changed: the moss contribution increased 21 times, while the proportion of lichens decreased by a factor of 1.1 in 2023. The results demonstrate a significant response of the Khibiny mountain tundra ecosystem to ongoing global warming during the study period. The rise in temperature at this stage of global climate change has led to an alteration in the structure of vegetation, namely an increased contribution of evergreen dwarf shrubs and mosses to the plant communities of the Khibiny Mountains.

Spatio-temporal variability of soil surface temperature affects adaptation of Antarctic hairgrass populations. 1. Fluctuations of average monthly local temperature near plants influence biometrical, biochemical, and ecological characteristics

Sun, 11 Jan 2026 00:00:00 +0100

A spatial-temporal temperature influence on Deschampsia antarctica populations adaptation was studied in the Galindez Island (Argentine Islands, the maritime Anatrctic) during seven consecutive Antarctic summer seasons (2017/19 – 2023/24). The subject of the research is the evaluation of complex adaptability (I^qk_i) characteristic for eleven populations of Deschampsia antarctica. Another goal was to analyze the temperature variables obtained with the help of microlimate loggers located at eleven sites, and their effects on the measured plant populations adaptability indices and to determine the united indices I^tk_i of their influence on them. Determination of the I^tk_i contribution to the complex index I^qk_i for eleven populations in the dynamics of seven summer seasons was calculated. Methods of determining the plants number in populations and measuring the morphometric indices of D. antarctica plants populations were used. Reserve and protective seed proteins were studied by polyacrylamide gel electrophoresis (PAGE). The spatial variables of these indices extreme grouping method were applied for eleven populations to obtain an I^qk_I and I^tk_i. Sets of complex indices were compared by regression technique. The populations forming general population (G-population) were found to develop unevenly depending on microconditions. In particular, individual populations with different frequencies matched into an asynchronous group, the populations of which were not matched of the general development trend of the G-population rest. The I^tk_i contributions to I^qk_i were shown be not always positive. Negative contributions were observed in the season k=3 (2019/20) and in some individual months of the seasons k=5, 6, 7.

Phenological development, viability, and visual tree assessment of Pinus sibirica du tour beyond the Arctic circle

Polina S. Zykova, Oxana A. Goncharova, Olesya E. Zotova — Sun, 11 Jan 2026 00:00:00 +0100

The study was performed on the Kola Peninsula and aimed to assess the impact of climatic factors on Pinus sibirica’s phenological development beyond the Arctic Circle in particular. Eight phenological parameters were analyzed, including vegetative bud swelling and breaking, initiation and cessation of annual linear shoot growth, full lignification of shoots, cessation of needle elongation and maturation, duration of linear lateral shoot growth, and needle growth period. Additionally, correlations between the onset of phenophases and temperature parameters, including average monthly and ten-day temperatures, the dates of the stable transition through the thresholds of 0, 5, and 10°C, sums of active temperatures above 0, 5, and 10°C for phenological phases and periods, monthly and ten-day sums of active temperatures, and monthly and ten-day cumulative sums of active temperatures starting from April, were investigated. Viability assessment involved evaluating the degree of annual shoot lignification, winter hardiness, habitus preservation, shoot-forming capacity, vertical shoot growth, generative reproduction, and reproduction in cultivation. Tree health categories were established based on examinations of root, butt, trunk, crown base, primary branches, and crown for indications of hollows, cracks, decay and fungal fruiting bodies, damage, wounds, weak forks, and dead branches. The onset dates of the phenophases occurring in the beginning of the vegetation period and full shoot lignification correlated with the dates of transition through the thresholds of 0 and 5°C. In contrast, the onset dates of the phenophases occurring in the middle of the vegetation period and duration of phenological periods correlated with accumulated temperatures above 0 and 5°C. The date of transition through 10°C and its associated parameters yielded uninformative results. The onset dates of all phenophases exhibit negative correlations with the following parameters: (1) average temperatures in April and May, (2) the sums of active temperatures (SATs) exceeding 0 and 5°C in May, (3) cumulative SATs above the thresholds of 0 and 5°C from April to May and June, and (4) cumulative ten-day SATs above the thresholds of 0 and 5°C before the onset of a phenophase. Pinus sibirica at Polar-Alpine Botanical Garden-Institute (PABGI) exhibited winter hardiness, maintained species-typical life form, and reached the generative stage of development. They were categorized as healthy or weakened. Visual inspection revealed no restrictions to root system growth. They displayed monocormic, unimucronate or bimucronate forms, with dense crowns and well-developed apical and lateral shoots. Some instances of reduced lateral shoot growth and V-shaped trunk forks were observed. Recommendations for regular monitoring, sanitary pruning and other agrotechnical measures have been formulated for the investigated tree individuals.