Polar Research (E-Journal)
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Trends in Antarctic ecological research in Latin America shown by publications in international journals
No full textAntarctica is a highly interesting region for ecologists because of its extreme climatic conditions and the uniqueness of its species. In this article, we describe the trends in Antarctic ecological research participation by Latin American countries. In a survey of articles indexed by the ISI Web of Science, we searched under the categories ‘‘Ecology,’’ ‘‘Biodiversity Conservation’’ and ‘‘Evolutionary Biology’’ and found a total of 254 research articles published by Latin American countries. We classified these articles according to the country of affiliation, kingdom of the study species, level of biological organization and environment. Our main finding is that there is a steady increase in the relative contribution of Latin American countries to Antarctic ecological research. Within each category, we found that marine studies are more common than terrestrial studies. Between the different kingdoms, most studies focus on animals and most studies use a community approach. The leading countries in terms of productivity were Argentina, Chile and Brazil, with Argentina showing the highest rate of increase.Keywords: Antarctica; Argentina; Brazil; Chile; research trends; scientific productivity(Published: 17 September 2013)Citation: Polar Research 2013, 32, 19993, http://dx.doi.org/10.3402/polar.v32i0.1999
Isolation and description of a globally distributed cryosphere cyanobacterium from Antarctica
No full textA previously uncultured cyanobacterium, strain KNUA009, was axenically isolated from a meltwater stream on Barton Peninsula, King George Island, South Shetland Islands, Antarctica. Molecular evidences showed that the isolate belongs to groups of globally distributed cryosphere cyanobacterial clones and this new isolate represents the first laboratory culture to be assigned to these groups. Strain KNUA009 was able to thrive at low temperatures ranging between 5°C and 20°C, but did not survive at temperatures of 25°C and above. As the isolate morphologically resembled Oscillatoria species, it is suggested that this cyanobacterium may represent a new species clade with cold resistance within the genus Oscillatoria.Keywords Barton Peninsular; cryosphere cyanobacteria; King George Island; uncultured Oscillatoria species.(Published: 8 August 2013)Citation: Polar Research 2013, 32, 18529, http://dx.doi.org/10.3402/polar.v32i0.1852
Contrasts between the cryoconite and ice-marginal bacterial communities of Svalbard glaciers
No full textCryoconite holes are foci of unusually high microbial diversity and activity on glacier surfaces worldwide, comprising melt-holes formed by the darkening of ice by biogenic granular debris. Despite recent studies linking cryoconite microbial community structure to the functionality of cryoconite habitats, little is known of the processes shaping the cryoconite bacterial community. In particular, the assertions that the community is strongly influenced by aeolian transfer of biota from ice-marginal habitats and the potential for cryoconite microbes to inoculate proglacial habitats are poorly quantified despite their longevity in the literature. Therefore, the bacterial community structures of cryoconite holes on three High-Arctic glaciers were compared to bacterial communities in adjacent moraines and tundra using terminal-restriction fragment length polymorphism. Distinct community structures for cryoconite and ice-marginal communities were observed. Only a minority of phylotypes are present in both habitat types, implying that cryoconite habitats comprise distinctive niches for bacterial taxa when compared to ice-marginal habitats. Curiously, phylotype abundance distributions for both cryoconite and icemarginal sites best fit models relating to succession. Our analyses demonstrate clearly that cryoconites have their own, distinct functional microbial communities despite significant inputs of cells from other habitats.Keywords: Cryoconite; glacier; Svalbard; moraines; niche; T-RFLP(Published: 22 May 2013)To access the supplementary material for this article, please see Supplementary Files in the column to the right (under Article Tools).Citation: Polar Research 2013, 32, 19468, http://dx.doi.org/10.3402/polar.v32i0.1946
A white humpback whale (Megaptera novaeangliae) in the Atlantic Ocean, Svalbard, Norway, August 2012
No full textA white humpback whale (Megaptera novaeangliae) was observed on several occasions off Svalbard, Norway, during August 2012. The animal was completely white, except for a few small dark patches on the ventral side of its fluke. The baleen plates were light-coloured, but the animal’s eyes had normal (dark) colouration. This latter characteristic indicates that the animal was not an albino; it was a leucistic individual. The animal was a full-sized adult and was engaged in ‘‘bubble-feeding’’, together with 1520 other humpback whales, each time it was seen. Subsequent to these sightings, polling of the marine mammal science community has resulted in the discovery of two other observations of white humpback whales in the Barents Sea area, one in 2004 and another in 2006; in both cases the observed individuals were adult animals. It is likely that all of these sightings are of the same individual, but there is no genetic or photographic evidence to confirm this suggestion. The rarity of observations of such white individuals suggests that they are born at very low frequencies or that the ontogenetic survival rates of the colour morph are low.Keywords: White humpback whale; Megaptera novaeangliae; Svalbard; leucism(Published: 26 April 2013)Citation: Polar Research 2013, 32, 19739, http://dx.doi.org/10.3402/polar.v32i0.1973
Standardized algal growth potential and/or algal primary production rates of maritime Antarctic stream waters (King George Island, South Shetlands)
No full textIn addition to the chemical analyses providing total nutrient content, standardized water trophic status bioassays are useful in the determination of available nutrients for primary producers. The aim of the study was to determine the standardized values of algal growth potential (AGP) and algal primary productivity rate (APPR) of maritime Antarctic stream water using modified AGP/APPR protocols. The standardized values of AGP and the APPR of oligotrophic and mesotrophic water samples from snow-melt streams were measured, and possible nutrient limitation and heavy metal inhibition were evaluated at 5°C and 25°C using polar and temperate strains of Stichococcus bacillaris, respectively. The water samples were enriched for the nutrient limitation tests with 1000 mμ l-1 NO3- -N, 50 μg l-1 PO43- -P, and a mixture of 1000 μg l-1 NO3- -N + 50 μg l-1 PO43- -P, and for the heavy metal inhibition tests with 1000 mg l-1 Na2-ethylenediaminetetraacetic acid (EDTA). The AGP of oligotrophic samples was significantly lower than that of the mesotrophic ones at both temperatures. In addition, AGP was significantly higher at 5°C than at 25°C. Oligotrophic samples were identified as being nitrogen limited, while no nutrient limitation was observed in the mesotrophic samples. No statistically significant heavy metal inhibition was observed at either temperature. The positive correlation of AGP and water nutrient content indicates that the method used accurately and comprehensively monitors the changes in biological availability of mineral nutrients and can provide a standardized reference point for similar exploration of freshwater ecosystems across both polar regions.Keywords: Maritime Antarctic; microalgae; nutrient limitations; snow-melt stream water(Published: 3 October 2013)Citation: Polar Research 2013, 32, 11191, http://dx.doi.org/10.3402/polar.v32i0.1119
Validation of parameterizations for the surface turbulent fluxes over sea ice with CHINARE 2010 and SHEBA data
No full textThis study examines the modelled surface turbulent fluxes over sea ice from the bulk algorithms of the Beijing Climate Centre Climate System Model (BCC_CSM), the European Centre for Medium-Range Weather Forecasts (ECMWF) model and the Community Earth System Model (CESM) with data from the fourth Chinese National Arctic Research Expedition (CHINARE 2010) and the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment. Of all the model algorithms, wind stresses are replicated well and have small annual biases (-0.6% in BCC_CSM, 0.2% in CESM and 17% in ECMWF) with observations, annual sensible heat fluxes are consistently underestimated by 83-141%, and annual latent heat fluxes are generally overestimated by 49-73%. Five sets of stability functions for stable stratification are evaluated based on theoretical and observational analyses, and the superior stability functions are employed in a new bulk algorithm proposal, which also features varying roughness lengths. Compared to BCC_CSM, the new algorithm can estimate the friction velocity with significantly reduced bias, 84% smaller in winter and 56% smaller in summer, respectively. For the sensible heat flux, the bias of the new algorithm is 30% smaller in winter and 19% smaller in summer than that of BCC_CSM. Finally, the bias of modelled latent heat fluxes is 27% smaller in summer.Keywords: Iceatmosphere coupling; turbulent flux parameterization; MoninObukhov similarity theory; SHEBA; stable boundary layer(Published: 23 September 2013)Citation: Polar Research 2013, 32, 20818, http://dx.doi.org/10.3402/polar.v32i0.2081
Kelp forest as a habitat for mobile epifauna: case study of Caprella septentrionalis Kröyer, 1838 (Amphipoda, Caprellidae) in an Arctic glacial fjord
No full textDistribution and abundance of the amphipod Caprella septentrionalis in relation to environmental conditions and habitat preferences were investigated in a kelp forest in Hornsund, Spitsbergen. Three sampling sites differed in hydrodynamics, organic and inorganic suspension concentration, and sedimentation rates. None of these abiotic factors or species of a macroalgal host appeared to have a significant influence on C. septentrionalis abundance and size range. An apparent preference towards the blade parts of the algal thalli was observed. These results support the idea of C. septentrionalis as a generalist Arcticboreal species that takes advantage of the protective nature of kelp forests.Keywords: Caprellid amphipod; Arctic fjord; kelp forest; population structure; distribution; macroalgae(Published: 20 November 2013)Citation: Polar Research 2013, 32, 21037, http://dx.doi.org/10.3402/polar.v32i0.2103
Electrical structure beneath Schirmacher Oasis, East Antarctica: a magnetotelluric study
No full textMaitri Station (70.76°S; 11.73°E) is located in Schirmacher Oasis, a coastal nunatak in north-central Dronning Maud Land covering an area of 35 km2. Here, we report results from the first magnetotelluric experiments and delineate the deep electrical conductivity structure under Schirmacher Oasis using the data acquired during the 24th Indian Antarctic Scientific Expedition. The magnetotelluric method has the advantage of shallow to deeper level coverage as the data acquisition covers a wide frequency band of 10-3103 Hz, permitting different penetration depths depending on the frequency and conductivity of the layer under investigation. The modelling results indicate the presence of a highly resistive (8000-10 000 ohm m) upper crust, which shows a lateral variation in thickness from 20 km (below site 6) in the east to 10 km (between sites 1 and 2) in the west. It is underlain by a less resistive (500-600 ohm m) lower crust. The highly resistive upper crustal structure supports the existing notion that western Dronning Maud Land is a stable, cratonic platform. Results of free-air gravity, seismic, geomagnetic and surface wave dispersion investigations in East Antarctica also indicate a cratonic-type crust. The results of our study allow us to identify a westward thinning of the upper crust with a marked boundary between sites 1 and 2. We also find evidence for the continuity of the Mozambique mobile belt in East Antarctica on the western side of Schirmacher Oasis.Keywords: Magnetotellurics; Schirmacher Oasis crustal structure; East Antarctica; Mozambique Belt; electrical conductivity(Published: 20 November 2013)Citation: Polar Research 2013, 32, 17309, http://dx.doi.org/10.3402/polar.v32i0.1730
Formation of Barents Sea Branch Water in the north-eastern Barents Sea
No full textThe Barents Sea throughflow accounts for approximately half of the Atlantic Water advection to the Arctic Ocean, while the other half flows through Fram Strait. Within the Barents Sea, the Atlantic Water undergoes considerable modifications before entering the Arctic Ocean through the St. Anna Trough. While the inflow area in the south-western Barents Sea is regularly monitored, oceanographic data from the outflow area to the north-east are very scarce. Here, we use conductivity, temperature and depth data from August/September 2008 to describe in detail the water masses present in the downstream area of the Barents Sea, their spatial distribution and transformations. Both Cold Deep Water, formed locally through winter convection and ice-freezing processes, and Atlantic Water, modified mainly through atmospheric cooling, contribute directly to the Barents Sea Branch Water. As a consequence, it consists of a dense core characterized by a temperature and salinity maximum associated with the Atlantic Water, in addition to the colder, less saline and less dense core commonly referred to as the Barents Sea Branch Water core. The denser core likely constitutes a substantial part of the total flow, and it is more saline and considerably denser than the Fram Strait branch as observed within the St. Anna Trough. Despite the recent warming of the Barents Sea, the Barents Sea Branch Water is denser than observed in the 1990s, and the bottom water observed in the St. Anna Trough matches the potential density at 2000 m depth in the Arctic Ocean.Keywords: Dense water formation; Kara Sea; deep water; Atlantic Water(Published: 20 September 2013)Citation: Polar Research 2013, 32, 18905, http://dx.doi.org/10.3402/polar.v32i0.1890
Reproductive biology of the Antarctic ‘‘sea pen’’ Malacobelemnon daytoni (Octocorallia, Pennatulacea, Kophobelemnidae)
No full textThe reproductive biology of the sea pen Malacobelemnon daytoni was studied at Potter Cove, South Shetland Islands, where it is one of the dominant species in shallow waters. Specimens collected at 15–22 m depth were examined by histological analysis. M. daytoni is gonochoristic and exhibited a sex ratio of 1:1. Oocyte sizes (>300 µm) and the absence of embryos or newly developed larvae in the colonies suggest that this species can have lecithotrophic larvae and experience external fertilization. This life strategy is in line with other members of the group and supports the hypothesis that this could be a phylogenetically fixed trait for pennatulids. It was observed that oocytes were generated by gastrodermic tissue and released to the longitudinal canal. Thereafter, they migrate along the canal until they reach maturity and are released by autozooids at the top of the colonies. This striking feature has not yet been reported for other pennatulaceans. Mature oocytes were observed from colonies of 15 mm in length, suggesting that sexual maturity can be reached rapidly. This is contrary to what is hypothesized for the vast majority of Antarctic benthic invertebrates, namely that rates of activities associated with development, reproduction and growth are almost universally very slow. This strategy may also explain the ecological success of M. daytoni in areas with high ice impact as in the shallow waters of Potter Cove.Keywords: Antarctica; benthic communities; Pennatulacea; reproduction; oogenesis(Published: 6 August 2013)Citation: Polar Research 2013, 32, 20040, http://dx.doi.org/10.3402/polar.v32i0.2004