Search results for "Antarctic Region"
showing 10 items of 25 documents
Social, Occupational, and Cultural Adaptation During a 12-Month Wintering in Antarctica.
2016
Background and methods Life in isolated and confined environments (ICEs) is subject to important constraints which can generate psychosociologically impaired outcomes. This study investigated psychological, social, occupational, and cultural variables which are among the most important determinants in adaptation to a one-year wintering in Antarctica for 13 international subjects. Results Our findings confirm and give further insight into the role of social (Cohesiveness, Social Support) and occupational (Implementation/Preparedness, Counterproductive Activity, Decision Latitude, and Psychological Job Demands) dimensions of adaptation to ICEs. Relationships between various social and occupat…
Species of Acryptolaria Norman, 1875 (Cnidaria: Hydrozoa) collected by US Antarctic and sub-Antarctic expeditions.
2020
Acryptolaria is a worldwide genus of deep-water benthic hydroids. The genus has relatively high species diversity, with 36 species described so far, yet most of them have been reported only occasionally. As a result, scientific knowledge of their ecology and distribution is scarce. Here I present the results of the study of species of Acryptolaria collected during several Antarctic and sub-Antarctic expeditions under the United States Antarctic Research Program between 1958 and 1986. Eight species were found in the collection (plus one determined to the genus level), with A. operculata having the highest occurrence. Acryptolaria flabellum is reported for the second time; the study also repr…
Solar UV-B radiation affects leaf quality and insect herbivory in the southern beech tree Nothofagus antarctica
2004
We examined the effects of solar ultraviolet-B (UV-B) radiation on plant-insect interactions in Tierra del Fuego (55°S), Argentina, an area strongly affected by ozone depletion because of its proximity to Antarctica. Solar UV-B under Nothofagus antarctica branches was manipulated using a polyester plastic film to attenuate UV-B (uvb-) and an Aclar film to provide near-ambient UV-B (uvb+). The plastic films were placed on both north-facing (i.e., high solar radiation in the Southern Hemisphere) and south-facing branches. Insects consumed 40% less leaf area from north- than from south-facing branches, and at least 30% less area from uvb+ branches than from uvb-branches. The reduced herbivory …
Phytoplankton communities of polar regions–Diversity depending on environmental conditions and chemical anthropopressure
2015
The polar regions (Arctic and Antarctic) constitute up to 14% of the biosphere and offer some of the coldest and most arid Earth's environments. Nevertheless several oxygenic phototrophs including some higher plants, mosses, lichens, various algal groups and cyanobacteria, survive that harsh climate and create the base of the trophic relationships in fragile ecosystems of polar environments. Ecosystems in polar regions are characterized by low primary productivity and slow growth rates, therefore they are more vulnerable to disturbance, than those in temperate regions. From this reason, chemical contaminants influencing the growth of photoautotrophic producers might induce serious disorders…
Assessing the conservation values and tourism threats in Barrientos Island, Antarctic Peninsula
2019
Antarctica has been witnessing continued growth of tourism, both in the overall visitation and in the diversity of itineraries and visitor activities. Expanding tourism presents unique business and educational opportunities, but it is also putting immense pressure on Antarctica's natural, and for the most parts, pristine environment. Understanding the effectiveness of different tourism management strategies and instruments, like the Visitor Site Guidelines adopted by the Antarctic Treaty, is fundamental to the sustainable management of Antarctic tourism. The purpose of this study was to assess the effectiveness of Visitor Site Guidelines and other tourism management actions in reducing impa…
High Diversity of the Viral Community from an Antarctic Lake
2009
Viruses are the most abundant biological entities and can control microbial communities, but their identity in terrestrial and freshwater Antarctic ecosystems is unknown. The genetic structure of an Antarctic lake viral community revealed unexpected genetic richness distributed across the highest number of viral families that have been found to date in aquatic viral metagenomes. In contrast to other known aquatic viromes, which are dominated by bacteriophage sequences, this Antarctic virus assemblage had a large proportion of sequences related to eukaryotic viruses, including phycodnaviruses and single-stranded DNA (ssDNA) viruses not previously identified in aquatic environments. We also o…
Additions to knowledge of the biodiversity of benthic hydroids (Cnidaria: Hydrozoa) in the Balleny Islands (Antarctica)
2021
The Balleny Islands, an isolated archipelago located 240 km off the coast of Victoria Land (East Antarctica), are separated from the Antarctic continental shelf by waters more than 2000 m deep. The benthic hydroid fauna of these islands is little known, with only 25 species reported so far. The present study contributes to a better knowledge of the benthic hydrozoans inhabiting this archipelago by studying a small collection held at the National Institute of Water and Atmospheric Research Invertebrate Collection at Wellington, New Zealand. Sixteen species of benthic hydroids were found in the collection, belonging to nine families and 12 genera of Leptothecata. Kirchenpaueriidae and Oswalde…
Identification of Morphological Biosignatures in Martian Analogue Field Specimens Using In Situ Planetary Instrumentation
2008
International audience; We have investigated how morphological biosignatures (i.e., features related to life) might be identified with an array of viable instruments within the framework of robotic planetary surface operations at Mars. This is the first time such an integrated lab-based study has been conducted that incorporates space-qualified instrumentation designed for combined in situ imaging, analysis, and geotechnics ( sampling). Specimens were selected on the basis of feature morphology, scale, and analogy to Mars rocks. Two types of morphological criteria were considered: potential signatures of extinct life ( fossilized microbial filaments) and of extant life (crypto-chasmoendolit…
F-type lectin from serum of the Antarctic teleost fish Trematomus bernacchii (Boulenger, 1902): Purification, structural characterization, and bacter…
2021
Abstract The increasing availability of sequenced genomes has enabled a deeper understanding of the complexity of fish lectin repertoires involved in early development and immune recognition. The teleost fucose-type lectin (FTL) family includes proteins that preferentially bind fucose and display tandemly arrayed carbohydrate-recognition domains (CRDs) or are found in mosaic combinations with other domains. They function as opsonins, promoting phagocytosis and the clearance of microbial pathogens. The Antarctic fish Trematomus bernacchii is a Perciforme living at extremely low temperatures (−1.68 °C) which is considered a model for studying adaptability to the variability of environmental w…
Recent evolution of the multi-isotopic radioactive content in ice of Livingston Island, Antarctica.
1999
The temporal arrangement of the ice layers that are produced in ecosystems with perpetual snows form situations that greatly favour the study of the temporal evolution of the radioactive fallout that occurs in the said zones, whether this fallout is natural or artificial in origin. This allows one to investigate the causes of the fallout and the mechanisms transporting the radionuclides involved from their source point to the study zone, as well as their subsequent behaviour in that zone. There are special difficulties involved in this type of study in Antarctica. Some are of a general character deriving from the conditions of extreme climate and isolation which complicate the processes of …