Antarctic Environment Research Articles

Persistent organic pollutants and mercury in a colony of Antarctic seabirds: higher concentrations in 1998, 2001, and 2003 compared to 2014 to 2016

Over decades, persistent organic pollutants (POPs) and trace metals like mercury (Hg) have reached the remotest areas of the world such as Antarctica by atmospheric transport. Once deposited in polar areas, low temperatures, and limited solar radiation lead to long environmental residence times, allowing the toxic substances to accumulate in biota. We investigated the load of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDTs) and metabolites (DDEs, DDDs) in embryos from failed eggs of the smallest seabird breeding in Antarctica, the Wilson's storm-petrel (Oceanites oceanicus) at King George Island (Isla 25 de Mayo). We compared samples of different developmental stages collected in 2001, 2003, and 2014 to 2016 to investigate changes in pollutant concentrations over time. We detected eight PCBs including the dioxin-like (dl) congeners PCB 105 and 118 (ΣPCBs: 59-3403 ng g−1 ww) as well as 4,4’-DDE, and 4,4’-DDD (ΣDDX: 19-1035 ng g−1 ww) in the embryos. Samples from the years 2001 and 2003 showed higher concentrations of PCBs than those from 2014 to 2016. Concentrations of DDX was similar in both time intervals. Furthermore, we determined Hg concentrations in egg membranes from 1998 to 2003, and 2014 to 2016. Similar to PCBs, Hg in egg membranes were higher in 1998 than in 2003, and higher in 2003 than in the years 2014 to 2016, suggesting a slow recovery of the pelagic Antarctic environment from the detected legacy pollutants. Embryos showed an increase in pollutant concentrations within the last third of their development. This finding indicates that contaminant concentrations may differ among developmental stages, and it should be taken into account in analyses on toxic impact during embryogenesis.

ANTARKTİKA SEFERLERİNDE ARAŞTIRMA GEMİLERİNİN KARBON EMİSYONLARININ İSTATİSTİKSEL YAKLAŞIMLA BELİRLENMESİ

Antarktika'da yapılan çalışmaların büyük çoğunluğu araştırma gemileri tarafından sağlanmaktadır. Bununla birlikte, araştırma gemilerinden kaynaklanan karbon emisyonlarının çevresel etkisine ilişkin veriler çok sınırlıdır. Bu çalışmada istatistiksel yöntemle iki farklı senaryo geliştirilerek Antarktika’da bilimsel amaçlı seferler yapan gemilerin emisyonlarının belirlenmesi ve daha sonra azaltılması için farklı yöntemlerin önerilmesi hedeflenmektedir. Araştırma gemisi ve uçakların yakıt tüketimi bu senaryolara göre hesaplandıktan sonra, literatürde yer alan emisyon faktörleri kullanılarak her senaryo için tüm kirletici gazların emisyon miktarları tahmin edilmiştir. İlk senaryoda, Avrupa'dan Antarktika'nın batısına sadece deniz yolu ile bilimsel seferler yapıldığı varsayılarak emisyon hesaplamaları yapılmıştır. İkinci senaryoda ise, aynı bölgeye hava yolu ile deniz yolu entegre bir şekilde kullanıldığı varsayılarak hesaplama yapılmıştır. Yalnızca deniz yolu kullanılan birinci senaryoda toplam 2143 ton CO2 emisyonu hesaplanırken, bunun %60’ının açık deniz seyrinden, %38’inin demirde beklemeden ve %2’sinin ise buzlu sularda seyirden kaynaklandığı saptanmıştır. Araştırma seferinin havayolu ile entegre edildiği ikinci senaryoda ise 1218 ton CO2 emisyonu hesaplanmış olup, burada emisyonun %66’sı demirde beklemeden, %21’i uçuştan, %10 açık deniz seyrinden ve %3’ü buzlu sularda seyirden kaynaklanmaktadır. Hesaplamalar, havayolu ile araştırma gemisinin birlikte kullanımının bu çalışma kapsamında emisyonları %57 oranında azaltabileceğini göstermektedir. Sonuç olarak, bu çalışma, Antarktika'ya coğrafi olarak yakın olmayan ülkelerin araştırma gemilerini doğrudan Antarktika seferleri için göndermek yerine hava ve deniz yolunu birlikte kullanmaları durumunda karbon emisyonlarının Antarktika çevresi üzerindeki etkilerinin azalabileceğini göstermektedir.

Field and laboratory investigation of factors affecting GCL performance in the Antarctic environment

Performance indicators of geosynthetic clay liners (GCLs) exposed to the Antarctic environment were assessed using field and laboratory methods. Barrier properties of the GCLs were not impacted by the field conditions and exhumed hydraulic conductivities with respect to tap water ranged from 0.4 × 10−11 to 12 × 10−11 m/s, compared to 5 × 10−11 m/s (virgin) and from 2.1 × 10−11 to 8.8 × 10−11 m/s for a synthetic leachate, compared to 2.5 × 10−11 to 7.6 × 10−11 m/s for virgin specimens. The self-healing ability of bentonite remained intact despite environmental exposure as evidenced by X-ray radiographs. Using a test plot to evaluate GCL hydration with the major determinant of hydration was identified as proximity to meltwater flow. However, a finer subgrade ( D60 = 5–7 mm) increased average and peak GCL moisture contents in areas not inundated with meltwater and resulted in less deformation than a coarse subgrade ( D60 > 16 mm). Additionally, X-ray radiographs showed increased self-healing in monitoring specimens overlying fine subgrades. Environmental exposure (e.g., temperature cycling and dehydration/rehydration) did not affect the hydraulic conductivity of test plot specimens (1.1 × 10−11 to 8.5 × 10−11 m/s) compared to the virgin GCL (6.7 × 10−11 m/s) with respect to tap water, and minimal cation exchange had occurred.

Sexually-manifested variations in pigmentation of Boeckella poppei (Copepoda, Calanoida) from Livingston Island (Maritime Antarctica)

Antarctic environments are exposed to high levels of ultraviolet radiation (UVR) that are often detrimental to their biota. Recent studies suggest that the genus Boeckella (Copepoda, Calanoida) has a high level of plasticity in terms of its reaction to UVR, which enables its wide distribution in various water bodies in Antarctica. Boeckella poppei is common in freshwater habitats of all three main biogeographic regions in Antarctica: sub-Antarctic islands, maritime and continental. We present for the first time a specific photoprotective response in populations of B. poppei from Livingston Island, Maritime Antarctica. In non-ovigerous females and in males, we observed uniform distribution of carotenoids in the body, while these pigments were almost entirely concentrated in the ovisacs of mature females. We consider this as a means of progeny protection from the teratogenic influence of the high level of UVR in Antarctic environments. Unequivocally, such adaptation would facilitate the expansion of B. poppei on the continent through colonisation and survival in shallow freshwater habitats. Given that the Antarctic environment is dynamically changing over the past decades and the accelerated retreat of permanent ice cover is a premise for the formation of shallow ponds, B. poppei could be a suitable indicator for reflecting the ongoing global environmental changes in Antarctica.

Antarctic Porifera homogenates as a source of enzymes and antibacterial substances: first results

Marine Porifera (sponges) are known to produce several bioactive metabolites having a biotechnological potential, mostly derived from their bacterial symbionts; however, current knowledge on the production of metabolites such as enzymes and antibacterial molecules in sponges living in Antarctic environments is not fully exhaustive and needs further deepened investigation. The interest in discovering the broad spectrum of natural products potentially derived from species adapted to colonize extreme environments stimulates the research toward Antarctic sponge bioprospection. In this study, whole homogenates of Antarctic Demospongiae, belonging to five different species [Haliclona (Rhizoniera) sp., Haliclona (Rhizoniera) dancoi, Microxina sarai, Dendrilla antarctica, and Mycale acerata] were collected from Terra Nova Bay (Ross Sea) and examined for presence and activity of enzymes, including lysozyme, and antibacterial substances. Enzyme activities (leucine aminopeptidase, beta-glucosidase, and alkaline phosphatase) were measured using fluorogenic substrates; lysozyme content was determined on plates containing lyophilized Micrococcus lysodeikticus cell walls as a substrate. Homogenates were screened in microtiter plates for their antibacterial activity against Antarctic bacterial isolates, and the absorbance reduction was measured with a microplate reader. All homogenates exhibited proteolytic, glycolytic, and phosphatasic activities, lysozyme and antibacterial activities at near “in situ” temperature (5 °C), with some differences among the examined species. Results confirmed that Antarctic sponge homogenates are interesting sources of different bioactive substances, likely produced from associated bacterial symbionts, and that could have great potential to be used in medicine or industrial applications.

Due Diligence and Compliance with the Protocol on Environmental Protection to the Antarctic Treaty

Abstract Due diligence standards have been read into treaty provisions for the protection for the environment and beyond in a wide range of international legal settings. The compliance provision of the Madrid Protocol on Environmental Protection to the Antarctic Treaty, Article 13, invites a similar analysis. Despite the doubts of ten years ago that a due diligence standard would be sufficient and appropriate for protecting the Antarctic environment the concept has arguably evolved to the point where it can provide an effective framework for operationalising States’ responsibilities under the Protocol as well as more widely in international environmental law, subject to adequate contextualisation.

Human adaptative behavior to Antarctic conditions: A review of physiological aspects.

The Antarctic environment induces adaptive metabolic and neuroendocrine changes associated with survival, as well as increased risks to physical and mental health. Circadian disruption has been observed in Antarctic expeditioners. The main consequences appear in quality of sleep, which can affect physical and cognitive performance. Physiological adaptation to cold is mediated by the norepinephrine and thyroid hormones (T3 and 3,5-T2 metabolite). The observed changes in the hypothalamic-pituitary-thyroid (HPT) axis of expeditioners varied according to temperature, photoperiod, time spent in the cold environment and stress level. The decrease in T3 levels has frequently been associated with mood swings. Psychological and physical stressors cause disturbances in the hypothalamic-pituitary-adrenal (HPA) axis, with consequent maintenance of high cortisol levels, leading to memory impairment, immunosuppression, and cardiometabolic and reproductive disorders. Preventive measures, such as provision of adequate food, well-established eating times, physical activity and even the use of phototherapy, can all help maintain the circadian rhythm. In addition, the use of high-tech clothing and room temperature control in research stations provide greater protection against the effects of intense cold. However, psychological stress requires a more individualized approach based on the crew's sociocultural characteristics, but it can be mitigated by mental healthcare and training in coping strategies. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Cardiovascular Diseases > Environmental Factors Metabolic Diseases > Environmental Factors.

Conservation Law in Antarctica and the Southern Ocean: the Antarctic Treaty System, conservation, and environmental protection

ABSTRACT The Antarctic Treaty System provides the corpus of law that governs the obligations of its Parties to protect and conserve the Antarctic environment. The System consists principally of the Antarctic Treaty (the Treaty), the Convention on the Conservation of Antarctic Marine Living Resources (CAMLR Convention), and the Protocol on Environmental Protection to the Antarctic Treaty (Environmental Protocol). The Antarctic Treaty establishes the Antarctic Treaty Consultative Meeting – the body that makes decisions under the provisions of the Treaty and Environmental Protocol. The CAMLR Convention establishes the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) – its decision-making body. Together, these two international bodies are responsible for the modern-day conservation and environmental management regimes for Antarctica and the Southern Ocean. This paper looks at the scope of law developed under the Antarctic Treaty System and its evolution; and at the interaction between the different components of the Antarctic Treaty System. The paper also forecasts some of the future challenges to conservation and environmental protection in Antarctica and the Southern Ocean.

Tourists’ motivations, learning, and trip satisfaction facilitate pro-environmental outcomes of the Antarctic tourist experience

Tourism in Antarctica has been growing and diversifying. While Antarctic tourists are purported to have meaningful interactions with the Antarctic environment, little empirical research exists to understand how motivations and trip characteristics of the Antarctic journey shape tourists' experiential outputs, which may in turn influence their pro-environmental outcomes. To examine these relationships, we conducted exploratory analyses using 242 pre-and post-trip surveys collected during the 2019–2020 Antarctic season. We identified four motivation types of Antarctic tourists: experience & learning, adventure into Antarctica, social bonding, and trip of a lifetime. Following the interactional model of tourist experience, we associated this motivation typology and trip characteristics with experiential outputs (Perceived Learning, Measured Learning, and Satisfaction) and pro-environmental outcomes (Environmental Concerns, Management Preferences, and Behavior Intentions). Our results indicated most tourists traveling to Antarctica already possessed high levels of pro-environmental attitudes and behavior intentions, leading to few significant changes after the journey. However, we found that the specific inputs of motivations and trip characteristics influenced experiential outputs in different ways -especially Perceived Learning and Satisfaction-, which were strongly associated with pro-environmental outcomes. Findings reinforce the importance of meaningful and transformative Antarctic tourist experiences in promoting sustainable human-environment interactions and provide new insights regarding tourists’ learning and experiential outcomes.

The Antarctic Weddell seal genome reveals evidence of selection on cardiovascular phenotype and lipid handling

The Weddell seal (Leptonychotes weddellii) thrives in its extreme Antarctic environment. We generated the Weddell seal genome assembly and a high-quality annotation to investigate genome-wide evolutionary pressures that underlie its phenotype and to study genes implicated in hypoxia tolerance and a lipid-based metabolism. Genome-wide analyses included gene family expansion/contraction, positive selection, and diverged sequence (acceleration) compared to other placental mammals, identifying selection in coding and non-coding sequence in five pathways that may shape cardiovascular phenotype. Lipid metabolism as well as hypoxia genes contained more accelerated regions in the Weddell seal compared to genomic background. Top-significant genes were SUMO2 and EP300; both regulate hypoxia inducible factor signaling. Liver expression of four genes with the strongest acceleration signals differ between Weddell seals and a terrestrial mammal, sheep. We also report a high-density lipoprotein-like particle in Weddell seal serum not present in other mammals, including the shallow-diving harbor seal.

Antarctic environments as a source of bacterial and fungal therapeutic enzymes.

Microbial therapeutic enzymes are the protagonists in the pharmacological treatment of different human diseases. The intrinsic enzymatic characteristics, such as high affinity and specificity to the corresponding substrate, enable effective therapies, with minimal adverse effects and complete remission. However, immunogenicity, short half-life, low enzymatic yield, and low selectivity regarding available enzyme drugs are currently the main obstacles to their development and the broad adherence to therapeutic protocols. By harboring adapted and still unexplored microbial life, environments of extreme conditions, such as Antarctica, become especially important in the prospecting and development of new enzymatic compounds that present higher yields and the possibility of genetic improvement. Antarctic microorganisms have adaptation mechanisms, such as more fluid cell membranes, production of antifreeze proteins and enzymes with more malleable structures, more robust, stable, selective catalytic sites for their respective substrates, and high antioxidant capacity. In this context, this review aims to explore enzymes synthesized by bacteria and fungi from Antarctica as potential drug producers, capable of providing therapeutic efficacy, less adverse effects, and lower production costs with highlight to L-Asparaginase, collagenase, superoxide dismutase and ribonucleases. In addition, this review highlights the unique biotechnological profile of these Antarctic extremophile microorganisms.

Extracellular hydrolytic enzymes produced by yeasts from Antarctic lichens.

In the Antarctic environment, yeasts are versatile eukaryotes that have shown wide dispersion in different substrates, producing active enzymes in extreme conditions, but their relevance in biotechnological applications is largely unknown. The aim of this study was to evaluate the production of extracellular hydrolases by yeasts isolated from Antarctic lichens and molecularly identify these isolates. From a total of 144 isolates on the screening, 109 (76%) produced at least one of the hydrolases tested, with most activities for proteases 59 (41%), cellulases 58 (40%), esterases 57 (39%), lipases 29 (20%), amylases 23 (16%) and pectinases 20 (14%). Among these isolates, 76 were identified, most belonged to the phylum Basidiomycota (n=73) with the dominance of Vishniacozyma victoriae (n=27), Cystobasidium alpinum (n=3), Mrakia niccombsii (n=3), Cystobasidium laryngis (n=2), Bannozyma yamatoana (n=2), Holtermanniella nyarrowii (n=2), and Glaciozyma martinii (n=2). This study is the first one reporting extracellular enzyme production by yeasts isolated from thallus of the species of Antarctic lichens Lecania brialmontii, Polycauliona candelaria, Usnea capillacea, Cladonia metacorallifera, and Polycauliona regalis. With these data, it's possible to confirm lichens as a source of hydrolase-producing yeasts, reinforcing the potential of these microorganisms in bioprospecting studies of catalytic molecules from polar regions that may be useful in promising biotechnological applications.

Antarctic fungi applied to textile dye bioremediation.

Antarctica has one of the most hostile conditions on the planet. The environmental characteristics found in this region favor the development of extremophile microorganisms, which are poorly explored biotechnologically. In this context, this study aimed at selectively isolating fungi with potential for the bioremediation of a textile dye. A total of 11 filamentous fungi were isolated from Antarctic samples after incubation in Minimal Mineral medium with the addition of Sulphur Indigo Blue dye. The Antarctic-derived fungi were submitted to textile dye decolorization analysis and biomass production. Isolates LAMAI 2400 and LAMAI 2402 showed more than 90% of decolorization at 15 °C, whereas at 28 °C these isolates showed 81.86 and 98.89%, respectively. In general, the toxicity of the bioassays, evaluated using Cucumis sativus, was higher than in the control. Both isolates, LAMAI 2400 and LAMAI 2402, were identified as Penicillium cf. oxalicum and classified as mesophilic-psychrotolerant. This fungal species has rarely been reported in the Antarctic environments. The results presented herein indicate the potential of the fungi recovered from Antarctic marine sediments for bioremediation of textile dyes at low and moderate temperatures, broadening the perspectives in the field of Antarctic mycology.

Natural gamma radiation at the sea level around the Antarctic continent recorded south of the 62° parallel

This study presents the results of dosimetry radiation measurement performed in the Antarctic region at the surface of the sea which was conducted between January and March 2018. Over 2 200 records were collected using a portable Gamma Scout Online radiometer during a 72-day voyage circumnavigating the continent of Antarctica. The mean average of the measured radiation dose rate was 0.091 μSvh-1 and varied from 0.052 to 0.193 μSvh-1. These result are above global average dose rate of radiation at sea level (0.031 μSvh-1) and often higher than those recorded on the Antarctic continent. Yet generally our records fall within well recognized latitudinal trend of radiation being higher toward poles. This is results of troposphere begins at lower altitude in Antarctic in comparison to lower latitudes. The origin of this radiation is natural and results from the presence of higher cosmic rays and secondary radiation induced in the atmosphere. The presence of terrestrial radionuclides in the Antarctic environment has a local, secondary influence on the measured values of radiation. The theoretical calculated annual dose equivalent for humans present in Antarctica could often exceed the limit of 1 mSv as recorded for other Antarctic locations yet our results (0.772 mSv per year) do not confirm that.

Effects of temperature and salinity on the sub-Antarctic snail Xymenopsis muriciformis (King and Broderip, 1832): Medium-term exposure to different climate change scenarios

As a consequence of climate change, benthic marine species that inhabit the sub-Antarctic oceans could be impacted as a result of changes in temperature and salinity that are affecting areas of high latitudes, where stenoic marine species are common. Therefore, the physiological performance of the species is essential to understand the ability of species to persist within their current range and to predict their rates of redistribution in response to the impacts of climate change impact. Xymenopsis muriciformis, an endemic sub-Antarctic benthic snail of the Strait of Magellan (53° 47′S; 70° 58′W), was used as a model species to understand the physiological response of a species that inhabits the Southern Oceans, where environmental conditions are very stable. We tested a medium-term exposure to the effects of climate change, including changes in temperature and salinity. The organisms were acclimatized for three months in the laboratory, at a temperature of 9 °C and salinity of 30 psu (control). The experiment was carried out for 60 days, where the ingestion rate and oxygen uptake were measured every 10 days. At the end of the experiments, the physiological condition of the organisms was determined by applying the metabolic indicators: carbohydrate indices (CHI), total lipids (TLI) and lipofuscins (LI), which were obtained by histological-histochemical analysis. The results indicated that temperature had significant effects on the ingestion rate and oxygen consumption, while salinity and the interaction between salinity and temperature had no significant effects. Organisms exposed to low temperatures (1 °C) and (5 °C), expected for the southern hemisphere summer, exhibited cellular degradation, which would limit the access and colonization of Antarctic environments. The organisms exposed to the 15 °C treatment (expected for the Magellan region), presented a significantly higher amount of lipofuscins in the vesicular connective tissue cells with morphological characteristics in the autophagosomes. We concluded that the snail X. muriciformis is a characteristic stenoic species, highly sensitive to temperature variations, as those projected in climate change scenarios for the Antarctic and sub-Antarctic regions.

First Report of Diversity of Cyanobacteria of Broknes Peninsula of Larsemann Hills, East Antarctica

Antarctica is an extreme environment and contains many unique geological, glaciological and biological features. However, due to changes in climatic conditions Antarctica is affected by Global warming. The Larsemann Hills area is located in East Antarctica approximately halfway between Vest fold Hills and Amery Ice Shelf on South-eastern coast of Prydz Bay which includes two main peninsulas, the western named Stornes and the eastern named Broknes. The Antarctic environment is highly sensitive and susceptible to the impacts of human activities and has much less natural ability to recover from disturbance than the environment of other continents. Due to coastal location and ice free landscape, Larsemann Hills is an attractive area for human activities which consit on scientific expeditions as well as touristic activities which are currently increasing. It is hypothesized that due to increase in land use pressure, the growth and diversity of Cyanobacteria in this area may be affected. The aim of this study was to record Cyanobacteria from freshwater bodies, rocks and terrestrial habitats. Considering the two main peninsulas, Stornes peninsula comes under the Antarctic Specially Protected Area (ACPA) so the samples were collected from diverse habitats of Broknes Peninsula. Altogether, 16 species of Cyanobacteria belonging to nine genera were recorded from diverse habitat of Broknes Peninsula of Larsemann Hills. This is the first Indian study report of Cyanobacteria of Broknes peninsula of Larsemann Hills. All species are reported for the first time and therefore constitutes new record from this area.

Sources and composition of chemical pollution in Maritime Antarctica (King George Island), part 1: Sediment and water analysis for PAH sources evaluation in the vicinity of Arctowski station

The paper presents a study regarding the identification of polycyclic aromatic hydrocarbons (PAHs) in fresh waters and surface sediments on the western shore of Admiralty Bay over four sampling seasons from 2017 to 2018. The results were compared to literature data from 2016 to provide a more comprehensive image of the environmental fate of PAHs over the years. The highest value of Σ PAHs was 82.9 ng/L and 445 ng/g dw in water and sediment samples, respectively. The analysis of PAH indicator ratio values showed that pyrogenic or mixed sources contribute to the PAH pollution in Antarctic sediments and water more than does petroleum. The main source is the combustion of biomass (e.g. as a result of fires) and coal, and PAHs are mostly associated with the activity of stations or are transported to a lesser extent by long-range atmospheric transport (LRAT) from South America. The values of the ΣLMW/ΣHMW ratio in sediments indicate that petrogenic sources contribute to PAH contamination, but among the six PAH ratios tested, petrogenic sources were identified as dominant in approximately 17–19% of cases. Lack of coherence in the obtained results confirms the mixed origin of PAHs in the studied samples. Although the differentiation of PAHs sources is still ambiguous, caution is recommended in light of the Antarctic system's evident and rapid response to global and local PAH emissions, and the dependency of accumulation and release cycle processes on weather conditions. A reduction in petrol usage in favour of renewable energy sources, and restriction of tourism are strongly recommended for better preservation of the pristine Antarctic environment.

Insight Into Ecology, Metabolic Potential, and the Taxonomic Composition of Bacterial Communities in the Periodic Water Pond on King George Island (Antarctica).

Polar regions contain a wide variety of lentic ecosystems. These include periodic ponds that have a significant impact on carbon and nitrogen cycling in polar environments. This study was conducted to assess the taxonomic and metabolic diversity of bacteria found in Antarctic pond affected by penguins and sea elephants and to define their role in ongoing processes. Metabolic assays showed that of the 168 tested heterotrophic bacteria present in the Antarctic periodic pond, 96% are able to degrade lipids, 30% cellulose, 26% proteins, and 26% starch. The taxonomic classification of the obtained isolates differs from that based on the composition of the 16S rRNA relative abundances in the studied pond. The dominant Actinobacteria constituting 45% of isolates represents a low proportion of the community, around 4%. With the addition of run-off, the proportions of inhabiting bacteria changed, including a significant decrease in the abundance of Cyanobacteria, from 2.38 to 0.33%, increase of Firmicutes from 9.32 to 19.18%, and a decreasing richness (Chao1 index from 1299 to 889) and diversity (Shannon index from 4.73 to 4.20). Comparative studies of communities found in different Antarctic environments indicate a great role for penguins in shaping bacterial populations.

Abiotic Stress-Induced Actin-Depolymerizing Factor 3 From Deschampsia antarctica Enhanced Cold Tolerance When Constitutively Expressed in Rice.

The Antarctic flowering plant Deschampsia antarctica is highly sensitive to climate change and has shown rapid population increases during regional warming of the Antarctic Peninsula. Several studies have examined the physiological and biochemical changes related to environmental stress tolerance that allow D. antarctica to colonize harsh Antarctic environments; however, the molecular mechanisms of its responses to environmental changes remain poorly understood. To elucidate the survival strategies of D. antarctica in Antarctic environments, we investigated the functions of actin depolymerizing factor (ADF) in this species. We identified eight ADF genes in the transcriptome that were clustered into five subgroups by phylogenetic analysis. DaADF3, which belongs to a monocot-specific clade together with cold-responsive ADF in wheat, showed significant transcriptional induction in response to dehydration and cold, as well as under Antarctic field conditions. Multiple drought and low-temperature responsive elements were identified as possible binding sites of C-repeat-binding factors in the promoter region of DaADF3, indicating a close relationship between DaADF3 transcription control and abiotic stress responses. To investigate the functions of DaADF3 related to abiotic stresses in vivo, we generated transgenic rice plants overexpressing DaADF3. These transgenic plants showed greater tolerance to low-temperature stress than the wild-type in terms of survival rate, leaf chlorophyll content, and electrolyte leakage, accompanied by changes in actin filament organization in the root tips. Together, our results imply that DaADF3 played an important role in the enhancement of cold tolerance in transgenic rice plants and in the adaptation of D. antarctica to its extreme environment.

Exploitation of Antarctic Iced Freshwater: A Call To Unfreeze Legal Discourse

While discussed within the Antarctic Treaty System during the 1970s-1980s, the idea of iceberg harvesting was laid on ice due to the lack of adequate technologies and scientific knowledge on the potential environmental implications. However, the State Parties to the ATS envisioned the possibility of reopening the legal discourse. For that purpose, iced freshwater resources exploitation was excluded from the scope of the Madrid Protocol containing a ban on all mineral mining activities within the scope ratione loci of the ATS. However, during the negotiations, it was agreed that if the prospect of iceberg harvesting was ever to be realised, the environmental protection provisions under the Madrid Protocol should apply. The present paper provides an analysis of whether the potential exploitation of iced freshwater resources proves realistic within the existing legal framework under the Antarctic Treaty System and the United Nations Convention on the Law of the Sea and discusses which rules States would need to adhere to when engaging in such activities. It arrives at the conclusion that, as to now, there is no prohibition of iceberg harvesting for freshwater use under international law. Nevertheless, both within the scope of the ATS and in the high seas, environmental regulations restrict the implementation of the activity and, therefore, require comprehensive environmental impact assessments to be conducted before the commencement of the activity. Furthermore, as ownership allocation of icebergs is not regulated under the relevant treaties, the present paper examines two legal regimes that may potentially govern iceberg acquisition in the high seas, namely, res nullius and res communis. Finally, as private efforts have become more far-reaching in the recent decades, an overview of the current state of practice is presented, highlighting the observed advantages and potential drawbacks. Conclusively, the present paper advocates for the reopening of the legal discourse on the subject matter before the commencement of exploitation activities so as to ensure that the fragile Antarctic environment is protected and preserved for the benefit of all humankind in accordance with the object and purpose of the ATS.