Bacterial diversity in ornithogenic soils compared to mineral soils on King George Island, Antarctica

In the Nar?bski Point area of King George Island of Antarctica, ornithogenic soils form on land under Chinstrap and Gentoo Penguin rookeries. The purpose of this study was to compare the bacterial community compositions in the gradient of contamination by penguin feces; mineral soil with no contamination, and soils with medium or high contamination. The discrimination between mineral soils and ornithogenic soils by characterization of physicochemical properties and bacterial communities was notable. Physicochemical analyses of soil properties showed enrichment of carbon and nitrogen in ornithogenic soils. Firmicutes were present abundantly in active ornithogenic soils, Bacteroidetes and Proteobacteria in a formerly active one, and several diverse phyla such as Proteobacteria, Actinobacteria, and Acidobacteria in mineral soils. Some predominant species belonging to the Firmicutes and Gammaproteobacteria may play an important role for the mineralization of nutrients in ornithogenic soils. Results of this study indicate that dominant species may play an important role in mineralization of nutrients in these ecosystems.     

Extracellular hydrolase enzyme production by soil fungi from King George Island, Antarctica

Various microbial groups are well known to produce a range of extracellular enzymes and other secondary metabolites. However, the occurrence and importance of investment in such activities have received relatively limited attention in studies of Antarctic soil microbiota. In order to examine extracellular enzyme production in this chronically low-temperature environment, fungi were isolated from ornithogenic, pristine and human-impacted soils collected from the Fildes Peninsula, King George Island, Antarctica during the austral summer in February 2007. Twenty-eight isolates of psychrophilic and psychrotolerant fungi were obtained and screened at a culture temperature of 4°C for activity of extracellular hydrolase enzymes (amylase, cellulase, protease), using R2A agar plates supplemented with (a) starch for amylase activity, (b) carboxymethyl cellulose and trypan blue for cellulase activity or (c) skim milk for protease activity. Sixteen isolates showed activity for amylase, 23 for cellulase and 21 for protease. One isolate showed significant activity across all three enzyme types, and a further 10 isolates showed significant activity for at least two of the enzymes. No clear associations were apparent between the fungal taxa isolated and the type of source soil, or in the balance of production of different extracellular enzymes between the different soil habitats sampled. Investment in extracellular enzyme production is clearly an important element of the survival strategy of these fungi in maritime Antarctic soils.     

Diversity of bacterioplankton in coastal seawaters of Fildes Peninsula,King George Island,Antarctica

The bacterioplankton not only serves critical functions in marine nutrient cycles, but can also serve as indicators of the marine environment. The compositions of bacterial communities in the surface seawater of Ardley Cove and Great Wall Cove were analyzed using a 16S rRNA multiplex 454 pyrosequencing approach. Similar patterns of bacterial composition were found between the two coves, in which Bacteroidetes, Alphaproteobacteria, and Gammaproteobacteria were the dominant members of the bacterioplankton communities. In addition, a large fraction of the bacterial sequence reads (on average 5.3 % per station) could not be assigned below the domain level. Compared with Ardley Cove, Great Wall Cove showed higher chlorophyll and particulate organic carbon concentrations and exhibited relatively lower bacterial richness and diversity. Inferred metabolisms of summer bacterioplankton in the two coves were characterized by chemoheterotrophy and photoheterotrophy. Results suggest that some cosmopolitan species (e.g., Polaribacter and Sulfitobacter) belonging to a few bacterial groups that usually dominate in marine bacterioplankton communities may have similar ecological functions in similar marine environments but at different geographic locations.     

The Bryophytes of the King George Island,Antarctica

After examining the moss collections from the King George Island collected by Dr. Wei Jiang-chun and Mr. Li Zhen-pei in 1983–1984 and 1985 separately, we find 7 species of the mosses, which belong to 4 families and 6 genera. Some of them such as the mosses of Calliergon and Drepanocladus favour moist habitats, whereas Andreaea obovata indicates the dry rocky substratum. Barbula unguiculata and Tortula ruralis could suffer non-permanent dry condition. Geographically, except Andreaea obovata and Calliergon stramineum the other mosses are almost cosmopolitans. They probably distributed to the King George Island before Antarctica drifting to the recent position, and the strong wind was also possible to blow the spores of mosses to Antarctica.     

Diversity and distribution of hidden cultivable fungi associated with marine animals of Antarctica

In the present study, we surveyed the distribution and diversity of fungal assemblages associated with 10 species of marine animals from Antarctica. The collections yielded 83 taxa from 27 distinct genera, which were identified using molecular biology methods. The most abundant taxa were Cladosporium sp. 1, Debaryomyces hansenii, Glaciozyma martinii, Metschnikowia australis, Pseudogymnoascus destructans, Thelebolus cf. globosus, Pseudogymnoascus pannorum, Tolypocladium tundrense, Metschnikowia australis, and different Penicillium species. The diversity, richness, and dominance of fungal assemblages ranged among the host; however, in general, the fungal community, which was composed of endemic and cold-adapted cosmopolitan taxa distributed across the different sites of Antarctic Peninsula, displayed high diversity, richness, and dominance indices. Our results contribute to knowledge about fungal diversity in the marine environment across the Antarctic Peninsula and their phylogenetic relationships with species that occur in other cold, temperate, and tropical regions of the World. Additionally, despite their extreme habitats, marine Antarctic animals shelter cryptic and complex fungal assemblages represented by endemic and cosmopolitan cold-adapted taxa, which may represent interesting models to study different symbiotic associations between fungi and their animal hosts in the extreme conditions of Antarctica.     

Culturable bacteria community development in postglacial soils of Ecology Glacier, King George Island, Antarctica

Glacier forelands are excellent sites in which to study microbial succession because conditions change rapidly in the emerging soil. Development of the bacterial community was studied along two transects on lateral moraines of Ecology Glacier, King George Island, by culture-dependent and culture-independent approaches (denaturating gradient gel electrophoresis). Environmental conditions such as cryoturbation and soil composition affected both abundance and phylogenetic diversity of bacterial communities. Microbiocenosis structure along transect 1 (severe cryoturbation) differed markedly from that along transect 2 (minor cryoturbation). Soil physical and chemical factors changed along the chronosequence (time since exposure) and influenced the taxonomic diversity of cultivated bacteria, particularly along transect 2. Arthrobacter spp. played a pioneer role and were present in all soil samples, but were most abundant along transect 1. Cultivated bacteria isolated from transect 2 were taxonomically more diverse than those cultivated from transect 1; those from transect 1 tended to express a broader range of enzyme and assimilation activities. Our data suggest that cryoturbation is a major factor in controlling bacterial community development in postglacial soils, shed light on microbial succession in glacier forelands, and add a new parameter to models that describe succession phenomena.     

Diversity and ecology of cultivable fungi isolated from the thermal soil gradients in Deception Island,Antarctica

We surveyed the diversity of cultivable fungi isolated from cold and hot volcanic soils of Deception Island, Antarctica. Seventy-four fungal isolates were identified; these belonged to 17 taxa in the genera Aspergillus, Penicillium, Pseudogymnoascus, Purpureocillium, and Mortierella. The fungal assemblages showed low diversity, richness, and dominance indices. The Aspergillus taxa were dominant in the soils at 0 °C, 50 °C, and 100 °C. Aspergillus lacticoffeatus, Aspergillus cf. ruber, Penicillium citrinun, and Purpureocillium sodanum were present only in soils having a temperature of 100 °C. Aspergillus calidoustus was present in all thermal soils and displayed the highest densities. The majority of fungi displayed mesophilic behavior; however, different isolates of Aspergillus lacticoffeatus and Aspergillus niger were able to grow at 50 °C; these are phylogenetically close to the causative agents of aspergillosis in immunocompromised individuals. Deception Island perhaps represents one of the most visited regions in Antarctica and the tourism there has increased over the last 20 years, especially by elderly tourists, probably with weak immune systems, come in contact with the resident microorganisms, including the thermo-resistant opportunistic Aspergillus species.

     

Mid-Holocene skua remains from King George Island,Antarctica

Seven avian remains from Mid-Holocene strata of the southeastern coast of Potter Peninsula (King George Island: Isla 25 de Mayo, South Shetland Islands, Antarctica) are reported. They were described and assigned to the brown skua Stercorarius antarcticus lonnbergi (Aves, Laridae), a living species currently breeding in the area. The presence of penguins in the same sequence is in agreement with the current dynamics of the coastal ecosystems of Antarctica. Nowadays, penguins and skuas frequent these same environments.     

Diversity of the lichenized fungi in King George Island, Antarctica, revealed by phylogenetic analysis of partial large subunit rDNA sequences

Lichens are predominant and important components of flora in the terrestrial ecosystem of Antarctica. However, relatively few researches on the phylogenetic position of Antarctic lichen-forming fungi have been accomplished. In this study, partial sequences of nuclear large subunit rDNAs from 50 Antarctic specimens were obtained and the phylogeny was reconstructed. Antarctic lichen species were distributed among 4 orders, including the monophyletic order Agyrales, paraphyletic orders Pertusariales and Teloschistales, and polyphyletic order Lecanorales. Species diversity was highest in the order Lecanorales, followed by Teloschistales and Pertusariales. Based on the phylogeny and sequence similarity analyses, it is proposed that the taxonomy of Stereocaulon alpinum, Physcia caesia, Usnea aurantiacoatra, and Cladonia species should be revised by careful examination of their phenotypic and molecular characteristics. Six species known to be endemic to Antarctica, Catillaria corymbosa, Himantormia lugubris, Leptogium puberulum, Pertusaria pertusa, Rhizoplaca aspidophora, and Umbilicaria antarctica, formed unique lineages, implying independent origins in the Antarctic area.     

Distribution of macroalgae and macroalgal communities in gradients of physical conditions in Potter Cove, King George Island, Antarctica

The vegetation of a small fjord and its adjacent open shore was documented by subaquatic video. The distribution of individual species of macroalgae and the composition of assemblages were compared with gradients of light availability, hydrography, slope inclination, substratum, and exposition to turbulence and ice. The sublittoral fringe is usually abraded by winterly ice floes and devoid of large, perennial algae. Below this zone, the upper sublittoral is dominated by Desmarestia menziesii on steep rock faces, where water movements become irregular, or by Ascoseira mirabilis and Palmaria decipiens on weakly inclined slopes with steady rolling water movements. In the central sublittoral above 15 m, where turbulence is still active, Desmarestia anceps is outcompeting all other species on solid substratum, However, the species is not able to persist on loose material under these conditions. Instead, Himantothallus grandifolius may occur. Deeper, where turbulence usually is negligible, Desmarestia anceps also covers loose material. The change of dominance to Himantothallus grandifolius in the deep sublittoral cannot completely be explained at present. Himantothallus grandifolius also prevails in a mixed assemblage under the influence of grounding icebergs. Most of the smaller algae are opportunists with different degrees of tolerance for turbulence, but some apparently need more stable microhabitats and thus are dependent from continuing suppression of competitive large phaeophytes.The present work is part of the Argentinian-German cooperation program RASCALS (Research on Antarctic shallow coastal and littoral systems).     

Influence of soil properties on the distribution of Deschampsia antarctica on King George Island, Maritime Antarctica

The extremely cold and infertile Antarctic is one of the harshest terrestrial ecosystems for the growth of vegetation, except for the grass species Deschampsia antarctica. We examined the main soil variables that determine the distribution of D. antarctica in King George Island by using Bayesian analysis of variance and regression methods. This study compared the density of D. antarctica between 2 sites; the density remained relatively stable at site 1, whereas it severely decreased in site 2 over a period of 3?years. Although site 2 showed better soil conditions for the growth of D. antarctica such as organic matter content, available phosphorus, NO₃-N, and extractable cations, its poor drainage and low soil pH may affected the survival of D. antarctica by altering nutrition availability and inhibiting root respiration. Poisson analysis of covariance showed that the early melting of snow was also an important factor in the distribution of D. antarctica. The results also showed that seabirds and mammals might have greatly influenced the distribution of the grass species in King George Island by transferring nutrients from the sea onto land; thus, changing the chemical characteristics of the soil.     

Diversity of endophytic fungi associated with bryophyte in the maritime Antarctic (King George Island)

Bryophytes comprise one of the richest microfungal microhabitats in the Antarctic environment. The maritime Antarctic is very vulnerable to rapid environmental change caused by global warming. The aim of this study was to investigate the importance of bryophytes as a microhabitat for fungal species in the maritime Antarctic by surveying endophytic fungal diversity from several bryophytes including Andreaea sp., Barbilophozia hatcheri, Chorisodontium aciphyllum, Polytrichum alpinum, Polytrichum strictum, Sanionia uncinata, and Warnstorfia sarmentosa. We collected 13 bryophyte samples at four localities on Barton Peninsula, King George Island. In total, 31 endophytic fungi morphotypes were isolated from bryophyte tissues by a thorough surface sterilization method. Using internal transcribed spacer sequence analysis, 16 endophytic fungal strains belonging to Ascomycota (12), Basidiomycota (1), Oomycota (1), and Zygomycota (2) phyla were obtained. Our results suggest the presence of a diverse range of fungal species even in a very limited area, and those bryophytes play an important role in conserving fungal diversity in this harsh environment. Growth rate measurements at a wide range of temperatures confirmed that most of the fungal strains were both mesophilic and psychrotolerant. This is the first report of endophytic fungi in Antarctic moss tissue by fluorescence in situ hybridization.     

The diversity,distribution, and pathogenic potential of cultivable fungi present in rocks from the South Shetlands archipelago,Maritime Antarctica

We studied the molecular taxonomy and diversity of cultivable rock fungi from Antarctic islands. From 50 rock samples, 386 fungal isolates were obtained and identified as 33 taxa of 20 genera. The genera Cladophialophora, Cladosporium, Cyphellophora, Eichleriella, Paracladophialophora, and Penicillium displayed the highest densities. Ecological diversity indices showed that the fungal assemblages are diverse and rich with low dominance. The genera Cladophialophora, Cladosporium, and Penicillium showed a broad distribution from rocks of the various islands. One hundred and fifty-nine fungi, grown at 37 °C, were identified as Penicillium chrysogenum, Fusarium sp., and Rhodotorula mucilaginosa. One hundred and three fungi displayed haemolytic activity, 81 produced proteinase, 9 produced phospholipase, and 25 presented dimorphism and a spore diameter ≤ 4 µm. The Antarctic Peninsula region appears to be under the effects of global climate changes, which may expose and accelerate the rock’s weathering processes, and expose and release cryptic fungi and other microbes, especially those with innate pathogenic potential, previously arrested in rocks. Consequently, these rocks and their particles may represent a vehicle for the dispersal of microbial propagules, including those able to spread pathogens, along, across, and out of Antarctica.

     

Meiofauna distribution in Martel Inlet, King George Island (Antarctica): sediment features versus food availability

The meiofauna density in Martel Inlet, Admiralty Bay, King George Island (Antarctica) was studied in order to better understand the spatial patterns of meiofauna distribution in shallow polar seas. Sampling was undertaken by scuba-diving at 15 m depth at 7 stations during the summers of 1996/1997 and 1997/1998. The meiofauna was dominated by nematodes (>60%), followed by copepods, nauplii and polychaetes. The mean densities found during the 2 years studied (4.09 and 3.5᎒⁶ ind. m^-2) suggest that the shallow area of Martel Inlet is characterized by higher numbers of meiofaunal organisms than are found in other ecosystems, which is in agreement with other meiofaunal studies carried out in polar areas. It may be concluded that it is mainly the sedimentary features that influence the meiofauna distribution. However, food availability must contribute to the support of the higher meiofauna densities found in the inlet.     

Diversity and structure of bacterial communities in Fildes Peninsula, King George Island

To examine the bacterial community structure in the Fildes Peninsula, King George Island, Antarctica, we examined the bacterial diversity and community composition of samples collected from lacustrine sediment, marine sediment, penguin ornithogenic sediments, and soils using culture-dependent and culture-independent methods. The 70 strains fell into five groups: Actinobacteria, Bacteroidetes, Firmicutes, Gammaproteobacteria, and Betaproteobacteria. Bacterial diversity at the phylum level detected in Denaturing Gradient Gel Electrophoresis (DGGE) profiles comprised Proteobacteria (including the subphyla Alpha-, Beta-, Gamma-, Deltaproteobacteria), Bacteroidetes, Firmicutes, Chlorobi, and Deinococcus-Thermus. Gammaproteobacteria was identified to be the dominant bacterial subphylum by cultivation and DGGE method. By cluster analysis, the overall structure and composition of bacterial communities in the soil and lacustrine sediment were similar to one another but significantly different from bacterial communities in penguin ornithogenic sediment and marine sediment, which were similar to one another. The majority of 16S rDNA sequences from cultured bacteria were closely related to sequences found in cold environments. In contrast, a minority of 16S rDNA sequences from the DGGE approach were closely related to sequences found in cold environments.     

Distribution of microphytobenthic biomass in Martel Inlet,King George Island (Antarctica)

The spatial and temporal variation of microphytobenthic biomass in the nearshore zone of Martel Inlet (King George Island, Antarctica) was estimated at several sites and depths (10–60 m), during three summer periods (1996/1997, 1997/1998, 2004/2005). The mean values were inversely related to the bathymetric gradient: higher ones at 10–20 m depth (136.2 ± 112.5 mg Chl a m⁻², 261.7 ± 455.9 mg Phaeo m⁻²), intermediate at 20–30 m (55.6 ± 39.5 mg Chl a m⁻², 108.8 ± 73.0 mg Phaeo m⁻²) and lower ones at 40–60 m (22.7 ± 23.7 mg Chl a m⁻², 58.3 ± 38.9 mg Phaeo m⁻²). There was also a reduction in the Chl a/Phaeo ratio with depth, from 3.2 ± 3.2 (10–20 m) to 0.7 ± 1.0 (40–60 m), showing a higher contribution of senescent phytoplankton and/or macroalgae debris at the deeper sites and the limited light flux reaching the bottom. Horizontal differences found in the biomass throughout the inlet could not be clearly related to hydrodynamics or proximity to glaciers, but with sediment characteristics. An inter-summer variation was observed: the first summer presented the highest microphytobenthic biomass apparently related to more hydrodynamic conditions, which causes the deposition of allochthonous material.     

Diversity of Both the Cultivable Protease-Producing Bacteria and Bacterial Extracellular Proteases in the Coastal Sediments of King George Island,Antarctica

Protease-producing bacteria play a vital role in degrading sedimentary organic nitrogen. However, the diversity of these bacteria and their extracellular proteases in most regions remain unknown. In this paper, the diversity of the cultivable protease-producing bacteria and of bacterial extracellular proteases in the sediments of Maxwell Bay, King George Island, Antarctica was investigated. The cultivable protease-producing bacteria reached 10⁵ cells/g in all 8 sediment samples. The cultivated protease-producing bacteria were mainly affiliated with the phyla Actinobacteria, Firmicutes, Bacteroidetes, and Proteobacteria, and the predominant genera were Bacillus (22.9%), Flavobacterium (21.0%) and Lacinutrix (16.2%). Among these strains, Pseudoalteromonas and Flavobacteria showed relatively high protease production. Inhibitor analysis showed that nearly all the extracellular proteases from the bacteria were serine proteases or metalloproteases. These results begin to address the diversity of protease-producing bacteria and bacterial extracellular proteases in the sediments of the Antarctic Sea.     

Breeding sites and population of seabirds on Admiralty Bay,King George Island,Antarctica

The monitoring of the status and distribution of seabird populations is necessary to understand their spatial and temporal responses to rapid climate changes occurring in the Western Antarctic Peninsula area. We surveyed and mapped Admiralty Bay bird communities and related them to climate variables—temperature, temperature anomaly, Antarctic Oscillation Index and El-Niño Southern Oscillation Index. We recorded 13 breeding seabird species over three seasons (2009/2010, 2010/2011 and 2011/2012) and mapped 10 of them over an area of 149.5 ha. The ice-free areas with the greatest number of species were Point Thomas, Keller Peninsula and Hennequin Point. The most abundant species was the Adelie Penguin (Pygoscelis adeliae) followed by the Chinstrap Penguin (P. antarcticus). We observed that the number of breeding pairs of Gentoo Penguins (P. papua), Chinstrap Penguins and skuas (Catharacta maccormicki and C. antarctica) are related to temperature, temperature anomaly and El-Niño Southern Oscillation Index. The size of breeding populations and their distributions have been fluctuating over the last 30 years in ice-free areas of Admiralty Bay. Most species showed a decreasing trend from 1978 to 2012, with the exception of Chinstrap Penguins, Southern Giant Petrels (Macronectes giganteus) and skuas, which seem to be stable in numbers in the last two decades. Decreases in seabird populations from the Antarctic Peninsula are widely recognized as a response to environmental change and anthropogenic influences such as tourism and building activities, thus highlighting the importance of monitoring to support mitigation measures.     

Microbial mats of twenty-six lakes from Potter Peninsula,King George Island,Antarctica

The taxonomic composition and ecology of microbial mats were investigated in 26 lentic environments of Potter Peninsula (King George Island, Antarctica) during the summer of 1995/96. These have different limnological characteristics according to the location of the basins. Among the 139 algal taxa registered, 10 are new records for Antarctica. Bacillariophyceae was the dominant class in terms of species richness, followed by the Cyanobacteria and Chlorophyceae. TWINSPAN classification was used to describe six epilithic algal assemblages; Canonical Correspondence Analysis ordination showed that soluble reactive phosphorus, phytoplanktonic chlorophyll a concentration and conductivity were the main sources for the variation in the data.     

Vertical distribution of macrobenthic infauna from the shallow sublittoral zone of Admiralty Bay,King George Island,Antarctica

A 0.0625 m² mini-box corer (MBC) was used to study the vertical distribution of macrobenthos in the shallow sublittoral zone of Admiralty Bay, during the 2003/2004 summer, near the Brazilian Station Comandante Ferraz, and the Peruvian Station Machu Picchu. Sediment samples were taken from 20, 30 and 60 m, and stratified for particle-size, total organic matter (TOM) and faunal composition analysis. The most abundant taxa were Polychaeta, Oligochaeta, Amphipoda, Cumacea, Bivalvia and Gastropoda. In general, macrofauna were concentrated in the 0–4 cm layer (64% of total organisms). Correlations between sediment characteristics and faunal densities have not completely explained neither the aggregation of organisms at the surface sediment layers nor the differences in faunal composition between locations at 20 m depth. Analysis of parameters such as organic carbon, heavy metals, interstitial water, and species composition should contribute to a better understanding of the diversity patterns found in this study.