1928 research outputs found
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Five-year bio-monitoring of aquatic ecosystems near Artigas Antarctic Scientific Base, King George Island
Get PDFFildes Peninsula, in King George Island, Antarctica, has a great concentration of international facilities, and it has clearly been affected by human activities. The objective of this 5-year study was to assess the impact of anthropogenic activities on the bacterial abundance in water bodies close to Artigas Antarctic Scientific Base (BCAA, in Spanish Base Científica Antártica Artigas). Water samples from areas under different human influence (Uruguay Lake, nearby ponds, and meltwater from Collins Glacier) were aseptically collected and refrigerated until processed. The number of heterotrophic bacteria and Pseudomonas spp. was analyzed using a culture-dependent approach. Physico-chemical properties of the water samples (temperature, pH, and conductivity) were also determined. Results showed that water from the highly affected area, Uruguay Lake, where the pump
that provides water to the BCAA is located, did not suffer significant fluctuations in heterotrophic bacterial abundance (104–105 CFU∙mL−1); however, Pseudomonas abundance increased until becoming the predominant population. In other water samples, the number of heterotrophic bacteria and Pseudomonas gradually increased during this 5-year study, by 2014 reaching similar values to those observed for Uruguay Lake. The implications of human activities on Antarctic bacterial abundance are discussed
A preliminary study of freshwater meiofaunal communities at Greenwich Island, South Shetland Islands, Antarctica
Get PDFMeiofaunal communities of three small, shallow freshwater habitats sampled during the austral summer of 2013 in Greenwich Island, South Shetland Islands, Antarctica, are reported. Communities are dominated by tardigrades (85%), nematodes (11%), and rotifers (3%). Collembola, Oligochaeta, crustacean larvae (nauplii) and unidentified organisms account for 0.3%. Total meiofaunal densities reach 11 770 ind∙cm-2, with mean densities (ind∙cm−2) of 1 365.83 ± 2 716.65 (Zone A), 523.67 ± 1 166.48(Zone B) and 72.17 ± 110.78 (Zone C). Given the age of freshwater habitats, and the general lack of higher-trophic level predatory taxa, those species we report are likely early stage colonizers, and these communities are at an early stage of ecological succession. Non-parametrical analysis revealed the main variables influencing meiofaunal density and distribution are related to granulometric characteristics of sediments and microphytobenthic biomass. There were close relationships between meiofaunal abundance and microphytobenthic biomass, which indicates that benthic microalgae significantly influence meiofaunal distribution. A strong correlation between nematode abundance and the percentage of silt, clay and carbon in the sediment was also shown by canonical correspondence analysis and Spearman rank correlation
Summer distribution of marine mammals encountered along transects between South Africa and Antarctica during 2007 – 2012 in relation to oceanographic features
Get PDFThe at-sea summertime distribution of marine mammals between South Africa and Antarctica was determined along eight transects surveyed between December 2007 and January 2012. During 1930 30-minute transect counts, 1390 marine mammal individuals were attributed to 19 species: eight toothed whales (Odontoceti), six pinnipeds, and five baleen whales (Mysticeti). An additional two toothed-whale species were encountered ‘out of effort’. The four most numerous species accounted for 85% of the total number of individuals encountered: crabeater seal (Lobodon carcinophagus), humpback whale (Megaptera novaeangliae), Antarctic Minke whale (Balaenoptera bonaerensis) and fin whale (B. physalus). The distribution of these species was related to oceanographic features, such as water masses and fronts, pack ice and ice edge: These differences were statistically highly significant. Biodiversity was compared with other polar marine ecosystems
Experimental culture of non-indigenous Juncus bufonius from King George Island, South Shetland Island, Antarctica
Get PDFJuncus bufonius L. (Juncaceae) is recognized by the US Department of Agriculture as a weed or invasive plant. Recently, we reported on J. bufonius L. var. bufonius associated with the native vascular plants Deschampsia antarctica and Colobanthus quitensis in the environs of the Polish Arctowski Station, King George Island, in the Maritime Antarctica. In this study, we evaluated the developmental stages and morphological characteristics of J. bufonius plants cultivated in controlled conditions beginning with seeds obtained from plants of the Antarctic population. Germination occurred at 3 weeks and the germination percentage was low (22.5%). The average time between the anthesis and seed formation was 7 weeks, similar to that reported for other species in the Juncaceae. According to data reported in the literature, Antarctic individuals were significantly smaller than their relatives growing in other conditions, except for the number of inflorescences. The morphological characteristics of a species vary according to its distribution and the edaphoclimatic environment where it occur; cosmopolitan plants shuch as J. bufonius also have reduced stature in cold environments. The low percentage germination may have been due to water availability in the plant chamber in which the study was conducted. J. bufonius is intolerant of dry environments, and once it suffers hydric stress its recovery is very low; thus, a moister environment could be beneficial. J. bufonius has become established amongst native vegetation near Arctowski Station and without careful control or eradication; it may have the potential to spread far beyond the site, as has happened with the alien grass Poa annua as human disturbance and climate warming increase
Preliminary evidence for 17 coastal terraces on Fildes Peninsula, King George Island, Antarctica
Get PDFThis study confirms the presence of 17 coastal terraces on Fildes Peninsula, Antarctica based on field observations and grain size analysis. The terraces formed by isostatic uplift during climate warming and glacier melting, and each level corresponds to a relatively stable period of climate. The grain size characteristics indicate an overlapping sedimentary origin for the sediments on the coastal terraces. The consistency of regional sea level rise, climate change, and glacial area suggest the presence of similar coastal terraces on King George Island since 18.0 ka
A mobile polar atmospheric parameter measurement system: II. First atmospheric turbulence observation at Antarctic Taishan Station
Get PDFThis is the second paper of a series devoted to atmospheric optical turbulence Cn
2 observation using a mobile polar atmospheric parameter measurement system. We present the initial results of Cn 2 measurement at Antarctic Taishan Station using micro-thermal sensors and a three-dimensional sonic anemometer at height ~2.0 m above the snow surface. The site testing experiments were carried out during the 30th Chinese National Antarctic Research Expedition (CHINARE). We collected about 1 000 h of data between 30 December 2013 and 10 February 2014. The Cn2 curve exhibits clear daily structures, with two peaks around midnight and midday and two troughs around 7:30 and 17:00 local time (UTC+5). The mean Cn2 is 2.7×10−15 m−2/3 and the 25th and 75th percentiles of the Cn2 cumulative distribution are 9.6×10−16 m−2/3 and 6.2×10−15 m−2/3, respectively. Meteorological parameters such as temperature, relative humidity, wind speed, and air pressure are also presented
Advancing the understanding of variations of Arctic sea ice optical and thermal behaviors through an international research and mobility project
Get PDFIn recent decades, significant changes of Arctic sea ice have taken place. These changes are expected to influence the surface energy balance of the ice-covered Arctic Ocean. To quantify this energy balance and to increase our understanding of mechanisms leading to observed changes in the Arctic sea ice, the project “Advancing Modelling and Observing solar Radiation of Arctic sea ice—understanding changes and processes (AMORA)” was initiated and conducted from 2009 to 2013. AMORA was funded and organized under a frame of Norway-China bilateral collaboration program with partners from Finland, Germany, and the USA. The primary goal of the project was achieved by developing an autonomous spectral radiation buoy, deploying it on drifting sea ice close to the North Pole, and receiving a high-resolution time series of spectral radiation over and under sea ice from spring (before melt onset) to autumn (after freeze-up) 2012. Beyond this, in-situ sea ice data were collected during several field campaigns and simulations of snow and sea ice thermodynamics were performed. More autonomous measurements are available through deployments of sea ice mass balance buoys. These new observational data along with numerical model studies are helping us to better understand the key thermodynamic processes of Arctic sea ice and changes in polar climate. A strong scientific, but also cultural exchange between Norway, China, and the partners from the USA and Europe initiated new collaborations in Arctic reseach
Arctic Human Development Report : Regional Processes and Global Linkages
Get PDFThe goals of the second volume of the AHDR – Arctic Human Development Report: Regional Processes and Global Linkages – are to provide an update to the first AHDR (2004) in terms of an assessment of the state of Arctic human development; to highlight the major trends and changes unfolding related to the various issues and thematic areas of human development in the Arctic over the past decade; and, based on this assessment, to identify policy relevant conclusions and key gaps in knowledge, new and emerging Arctic success stories.
The production of AHDR-II on the tenth anniversary of the first AHDR makes it possible to move beyond the baseline assessment to make valuable comparisons and contrasts across a decade of persistent and rapid change in the North. It addresses critical issues and emerging challenges in Arctic living conditions, quality of life in the North, global change impacts and adaptation, and Indigenous livelihoods.
The assessment contributes to our understanding of the interplay and consequences of physical and social change processes affecting Arctic residents’ quality of life, at both the regional and global scales. It shows that the Arctic is not a homogenous region. Impacts of globalization and environmental change differ within and between regions, between Indigenous and non-Indigenous northerners, between genders and along other axes
Methanesulphonic acid in aerosols along a cruise path from China to the Arctic Ocean: Spatial and temporal distributions and link with iodine
Get PDFMethanesulphonic acid (MSA) may play an important role in the climate change occurring in response to the warming of the Arctic Ocean. However, the spatial and temporal distributions of MSA in this region are poorly understood. We report on the MSA content of aerosols over oceans measured during the 3rd Chinese National Arctic Research Expedition (CHINARE2008) from July to September, 2008. Results show that the aerosol MSA content can be influenced by multiple processes in different areas. In coastal regions, airborne pollutants, especially nitric oxide, may strongly influence the oxidation of dimethyl sulfide (DMS) and increase the concentration of aerosol MSA. In remote areas of the Pacific and Arctic oceans, changes in plankton will indirectly influence the airborne MSA concentration. Moreover, we found fairly similar trends in the variation of the concentrations of total iodine (TI) and MSA in the Arctic during CHINARE2008, suggesting that iodine and MSA may come from similar sources in the Arctic. Compared with the findings from other two cruises, CHINARE1999 and CHINARE2012, we found that sea ice is an extremely important factor that influences the aerosol MSA content in the Arctic. In addition, MSA concentrations may increase in the Arctic in the future caused by sea ice melting due to global warming
