Diversity and ecology of fungal assemblages present in lake sediments at Clearwater Mesa,James Ross Island,Antarctica, assessed using metabarcoding of environmental DNA

We detected the fungal assemblages present in lake sediments on James Ross Island, Antarctica, using DNA metabarcoding. A total of 132 amplicon sequence variants (ASVs) were assigned, dominated by taxa of the phyla Ascomycota, Basidiomycota, Mortierellomycota and Mucoromycota. The less common phyla Chytridiomycota, Rozellomycota, Monoblepharomycota, Basidiobolomycota, Aphelidiomycota and the fungus-like Straminopila were also detected. Fungal sp. 1, Fungal sp. 2, Spizellomycetales sp. 1, Rozellomycotina sp. 1, Talaromyces rubicundus and Betamyces sp. dominated the assemblages. In general, the assemblages displayed high diversity and richness, and moderate dominance. Saprophytic, pathogenic and symbiotic fungi were detected. The metabarcoding data indicated that Antarctic lakes may represent a hotspot of fungal diversity in Antarctica. The sediments of these lakes may accumulate different fungal fragments and active fungal mycelia and their propagules, deposited over long periods of time. Lakes in the Antarctic Peninsula region are sensitive environments threatened by the effects of regional climatic changes. The abundance of sequences of little-known Rozellomycota and Chytridiomycota (Spizellomycetales) taxa in these ecosystems highlights the need for further studies to identify if they are metabolically active in the sediments and whether they have potentially pathogenic capabilities.     

The terrestrial arthropod fauna of the Byers Peninsula,Livingston Island,South Shetland Islands

We report the first detailed study of the terrestrial invertebrate fauna of the Byers Peninsula SSSI, Livingston Island, South Shetland Islands. Fourteen micro-arthropod taxa (10 Acari, four Collembola) and two Diptera are recorded, including the first record of the mite Edwardzetes dentifer from the maritime Antarctic. The first record of the midge Belgica antarctica from neighbouring Snow Island is also given. Population composition and density were described in samples from a wide range of terrestrial and freshwater habitats. There was no strong relationship between habitat and microarthropod species occurrence, although comparison of completely vegetated and more stony sites revealed greater population densities at the vegetated sites, and different species proportions at each. Some individual samples contained a wide range of species with none achieving numerical dominance, whilst others from superficially similar sites were dominated by one species. Dipterans were limited to a small number of lakes, streams and seepage areas, where they were sometimes abundant. Population density data and species occurrence are compared with previously published studies from the maritime Antarctic and elsewhere.     

A curious occurrence of Hazenia broadyi spec. nova in Antarctica and the review of the genus Hazenia (Ulotrichales, Chlorophyceae)

Freshwater filamentous green algae with branched thalli are almost unknown from the Antarctic region. They have rarely been recorded from maritime Antarctica and from sub-Antarctic Islands with rich phanerogamic vegetation. In the genus Hazenia, only one unidentified species was reported from several subaerial sites on Signy Island in 1979. However, unique populations of this genus were recently found in the stony littoral zone of two stable shallow lakes in the northern deglaciated region of James Ross Island (NE Antarctic Peninsula). These populations have a specialized ecology; they participate in the microvegetation on the flattened surfaces of stones in the littoral zones of lakes. The dominant green filamentous and richly branched alga from these communities was transferred to monospecific culture and studied in detail. Molecular sequence data (18S ribosomal DNA and the internal transcribed spacer) indicate that it belongs to the genus Hazenia (Bold in Am J Bot 45:737–743, 1958). Based on distinct molecular, morphological, and ecological characters, this alga was described as a new species (Hazenia broadyi spec. nova). A review of the genus Hazenia, based on molecular phylogenetic analyses of available strains, was also performed.     

The vegetation of Cockburn Island,Antarctica

Cockburn Island, off the north-east Antarctic Peninsula, is important in the history of Antarctic terrestrial biology as it was here where the first botanical collections were made by JD Hooker in 1843. These, and a subsequent collection made by IM Lamb one hundred years later, are described here. A much more detailed survey of the vegetation of the island was made in 1989. At least nine moss, 34 lichen, three cyanobacteria and one alga taxa were recorded, and the floristic composition of several distinct communities assessed. The floristically most interesting and diverse sites are on the island's 250 m high plateau which possesses seepage areas and welldeveloped networks of polygons and stone circles. The vegetation is similar to that occurring on the mainly sedimentary deposits and rocks of nearby James Ross and Seymour Islands, but significantly different to that on the more acidic soils and rocks which predominate throughout much of the maritime Antarctic.     

The fossil record of Cunoniaceae: new evidence from Late Cretaceous wood of Antarctica?

Fossil angiosperm wood from Upper Cretaceous sediments of Livingston Island and James Ross Island in the northern Antarctic Peninsula region is identified as having the combination of anatomical characters most similar to modern Cunoniaceae. The material is characterised by predominantly solitary vessels, opposite to scalariform intervessel pitting, scalariform perforation plates, heterocellular multiseriate and homocellular uniseriate rays, diffuse axial parenchyma. Anatomically, the specimens conform most closely to the fossil organ genus Weinmannioxylon Petriella which has been placed within the Cunoniaceae. The presence of Weinmannioxylon in Late Cretaceous sediments suggests that taxa within or stem taxa to the Cunoniaceae might have been a notable component of the forest vegetation that covered the Antarctic Peninsula during the Late Mesozoic and may therefore represent the earliest record of this family.     

Diversity of fungal DNA in lake sediments on Vega Island,north-east Antarctic Peninsula assessed using DNA metabarcoding

Extremophiles - We assessed the diversity of fungal DNA present in sediments of three lakes on Vega Island, north-east Antarctic Peninsula using metabarcoding through high-throughput sequencing...     

The diatom flora and limnology of lakes in the Amery Oasis,East Antarctica

The diatom flora of three lakes in the ice-free Amery Oasis, East Antarctica, was studied. Two of the lakes are meltwater reservoirs, Terrasovoje Lake (31 m depth) and Radok Lake (362 m depth), while Beaver Lake (>435 m depth) is an epishelf lake. The lakes can be characterized as cold, ultra-oligotrophic and alkaline, displaying moderate (Radok and Terrasovoje lakes) to high (Beaver Lake) conductivities. There was no diatom phytoplankton present in any of the three lakes. While 34 benthic diatom taxa were identified from modern and Holocene sediments of Terrasovoje and Radok lakes, a 30-cm long sediment core recovered in Beaver Lake was barren. Five species (Luticola muticopsis, Muelleria peraustralis, Pinnularia cymatopleura, Psammothidium metakryophilum, P. stauroneioides) are endemic to the Antarctic region. All identified taxa are photographically documented and brief notes on their taxonomy, biogeography and ecology are provided. The most abundant diatom taxa are Amphora veneta, Craticula cf. molesta, Diadesmis spp, M. peraustralis and Stauroneis anceps. This is the first report on the diatom flora in lakes of the Amery Oasis.This revised version was published online in May 2004 with corrections to Figure 1.     

Diversity and bioprospecting of cultivable fungal assemblages in sediments of lakes in the Antarctic Peninsula

We recovered 195 fungal isolates from the sediments of different lakes in the Antarctic Peninsula, which were screened to detect bioactive compounds. Forty-two taxa belonging to the phyla Ascomycota, Basidiomycota, and Mortierellomycota were identified. Thelebolus globosus, Antarctomyces psychrotrophicus, Pseudogymnoascus verrucosus, Vishniacozyma victoriae, and Phenoliferia sp. were found to be the most prevalent. The fungal assemblages showed high diversity and richness, but low dominance values. However, the diversity indices and fungal distribution ranged according to the different lake sediments. Sixty fungal extracts displayed at least one biological activity against the evaluated targets. Among them, Pseudogymnoascus destructans showed selective trypanocidal activity, Cladosporium sp. 1 and Trichoderma polysporum showed antifungal activity, and Pseudogymnoascus appendiculatus and Helotiales sp. showed high herbicidal activity. We detected a rich and diverse fungal community composed of cold cosmopolitan and psychrophilic endemic taxa recognized as decomposers, symbiotics, pathogens, and potential new species, in the sediments of Antarctic lakes. The dynamics and balance of this fungal community represents an interesting aquatic web model for further ecological and evolutionary studies under extreme conditions and potential climate changes in the regions. In addition, we detected fungal taxa and isolates able to produce bioactive compounds that may represent the source of prototype molecules for applications in medicine and agriculture.     

A comparison of epiphytic diatom communities on <Emphasis Type="Italic">Plocamium cartilagineum</Emphasis> (Plocamiales,Florideophyceae) from two Antarctic areas

Our understanding of diatoms, one of the most important Antarctic primary producers, is based mostly on investigations of plankton, sea-ice, and sediment samples. Herein, we contribute to the limited research devoted to benthic Antarctic diatoms by presenting a study on epiphytic diatom communities sampled in two remote Antarctic regions: Admiralty Bay (maritime Antarctica, Antarctic Peninsula) and Terra Nova Bay (Ross Sea). Recent studies have demonstrated that the most critical factor for the local epiphytic diatom communities was the nature of the substrate. In order to eliminate this factor so we could evaluate other potential controls, we sampled epiphytic diatoms from only one substrate that is common to both regions: the macroalgae Plocamium cartilagineum (L.) Dixon. Thalli of P. cartilagineum and their associated microalgal community was collected in January 2011 (Admiralty Bay) and 2012 (Terra Nova Bay) from a water depth of 5–25 m. Dehydrated macroalgal pieces were placed on stubs and sputter-coated, which allowed observation of diatoms attached to the substrate in their original position using scanning electron microscopy. A total of 72 taxa were observed, of which 31 taxa were common to both regions. Cell abundance and diatom growth form dominance were significantly different in Admiralty Bay and Terra Nova Bay samples. Total diatom abundance was higher in Admiralty Bay samples, dominated by adnate diatoms (Cocconeis spp.), but the number of taxa found as well as the values of ecological indices were higher for samples from the Ross Sea, where motile forms were dominant (Navicula spp.). Our results suggest that Antarctic shallow-water benthic habitats may present a high degree of microniche heterogeneity and highlight the need of fine-scale analyses in microbial studies. We also suggest grazers as a factor that contributes greatly to the observed differences.     

Processes regulating the community composition and relative abundance of taxa in the diatom communities of the Malili Lakes, Sulawesi Island, Indonesia

Although high levels of endemism have been reported on Sulawesi Island for almost 150 years, the aquatic systems of the island have received little attention until recently. The diatoms of the ancient Malili Lakes, located on central Sulawesi, exhibit levels of endemism unequaled elsewhere in the world. Interestingly, the diatom community of the lakes is taxonomically impoverished, and the entire order Centrales is conspicuous by its absence. In this article we review the mechanisms contributing to the development and maintenance of community composition and relative abundance of taxa within the system, at within-lake and system-wide scales. Our findings demonstrate that stochastic processes related to biogeography and colonization have had little influence on the diatom flora of the lakes, and deterministic processes related to competition, selection, speciation, and adaptive radiation, functioning on very small spatial scales, have contributed greatly to the diversity, community structure, and endemism of the system.     

Diversity,ecology, and bioprospecting of culturable fungi in lakes impacted by anthropogenic activities in Maritime Antarctica

In this study, we accessed culturable fungal assemblages present in the sediments of three lakes potentially impacted anthropogenically in the Fildes Peninsula, King George Island, Antarctica and identified 63 taxa. Cladosporium sp. 2, Pseudeurotium hygrophilum, and Pseudogymnoascus verrucosus were recovered from the sampled sediments of all lakes. High concentrations of metals and the lowest fungal diversity indices were detected in the sediments of the Central Lake, which can be influenced by human activities due to their proximity to research stations to those of the other two lakes, which were far from the Antarctic stations. At least one type of biological activity was demonstrated by 40 fungal extracts. Among these, P. hygrophilum, P. verrucosus, Penicillium glabrum, and Penicillium solitum demonstrated strong trypanocidal, herbicidal, and antifungal activities. Our results suggest that an increase of the anthropogenic activities in the region might have affected the microbial diversity and composition. In addition, the fungal diversity in these lakes may be a useful model to study the effect of anthropogenic activities in Antarctica. We isolated a diverse group of fungal taxa from Antarctic lake sediments, which have the potential to produce novel compounds for the both the medical and agriculture sectors.

     

Diversity Patterns,Ecology and Biological Activities of Fungal Communities Associated with the Endemic Macroalgae Across the Antarctic Peninsula

We surveyed diversity patterns and engaged in bioprospecting for bioactive compounds of fungi associated with the endemic macroalgae, Monostroma hariotii and Pyropia endiviifolia, in Antarctica. A total of 239 fungal isolates were obtained, which were identified to represent 48 taxa and 18 genera using molecular methods. The fungal communities consisted of endemic, indigenous and cold-adapted cosmopolitan taxa, which displayed high diversity and richness, but low dominance indices. The extracts of endemic and cold-adapted fungi displayed biological activities and may represent sources of promising prototype molecules to develop drugs. Our results suggest that macroalgae along the marine Antarctic Peninsula provide additional niches where fungal taxa can survive and coexist with their host in the extreme conditions. We hypothesise that the dynamics of richness and dominance among endemic, indigenous and cold-adapted cosmopolitan fungal taxa might be used to understand and model the influence of climate change on the maritime Antarctic mycota.     

Diversity of the cyanobacterial microflora of the northern part of James Ross Island,NW Weddell Sea,Antarctica

The diversity and ecological distribution of cyanobacteria in the northern, deglaciated part of James Ross Island were studied during the Antarctic summer season 2005–2006. Seventy-five cyanobacterial morphotypes were observed in various habitats of this area. The identified cyanobacterial taxa belong to the characteristic and dominant types of coastal Antarctica, and majority of them appeared connected to special habitats and formed distinct populations and ecologically delimited communities. The results are compared and discussed with respect to phenotypically characterised cyanobacterial microflora of maritime Antarctica and to recent molecular analyses of cyanobacterial strains from different Antarctic regions. The existence of a specificity and characteristic composition of Antarctic cyanobacterial communities was demonstrated.     

Diatom community response to an acid mine drainage gradient

Acid mine drainage (AMD) is a significant environmental issue worldwide. On the West Coast of the South Island, New Zealand, many AMD-affected streams occur within close proximity to naturally acidic streams, enabling us to compare the response of communities in naturally and anthropogenic acidified systems. We investigated epiphytic diatom communities in 39 streams along an AMD gradient that included naturally acidic and circum-neutral reference streams. There was a wide range in taxonomic richness in reference streams and those moderately impacted by AMD (8–33 taxa). Taxonomic richness was greatly reduced in severely impacted streams (1–5 taxa) at a threshold of pH 3.4 and was dominated by Pinnularia cf. acidophila (69–100% relative abundance). Community composition differed between circum-neutral reference streams and moderately and severely impacted streams. However, naturally acidic and moderately impacted streams had similar diatom communities primarily composed of Eunotia and Frustulia species. Our results indicate that diatom communities are strongly structured by pH and able to tolerate moderate conductivity and metal concentrations. This is a challenge for researchers and water managers attempting to incorporate diatoms into AMD monitoring in regions with naturally acidic streams.     

Heterolobosean amoebae from Arctic and Antarctic extremes: 18 novel strains of Allovahlkampfia,Vahlkampfia and Naegleria

The diversity of heterolobosean amoebae, important members of soil, marine and freshwater microeukaryote communities in the temperate zones, is greatly under-explored in high latitudes. To address this imbalance, we studied the diversity of this group of free-living amoebae in the Arctic and the Antarctic using culture dependent methods. Eighteen strain representatives of three heterolobosean genera, Allovahlkampfia Walochnik et Mulec, 2009 (1 strain), Vahlkampfia Chatton et Lalung-Bonnaier, 1912 (2) and Naegleria Alexeieff, 1912 (15) were isolated from 179 samples of wet soil and fresh water with sediments collected in 6 localities. The Allovahkampfia strain is the first representative of the genus from the Antarctic; 14 strains (7 from the Arctic, 7 from the Antarctic) of the highly represented genus Naegleria complete the ‘polar’ cluster of five Naegleria species previously known from the Arctic and Sub-Antarctic regions, whereas one strain enriches the ‘dobsoni’ cluster of Naegleria strains of diverse origin. Present isolations of Naegleria polaris De Jonckheere, 2006 from Svalbard, in the Arctic and Vega Island, in the Antarctic and N. neopolaris De Jonckheere, 2006 from Svalbard and Greenland in the Arctic, and James Ross Island, the Antarctic demonstrate their bipolar distribution, which in free-living amoebae has so far only been known for Vermistella Morand et Anderson, 2007.     

Concentrations of Thirteen Trace Metals in Scales of Three Nototheniid Fishes from Antarctica (James Ross Island,Antarctic Peninsula)

In this study, we assessed concentrations of 13 trace metals in the scales of Notothenia coriiceps, Trematomus bernacchii and Gobionotothen gibberifrons caught off the coast of James Ross Island (Antarctic Peninsula). Overall, our results for scales broadly match those of previous studies using different fish and different organs, with most metals found at trace levels and manganese, aluminium, iron and zinc occurring at high levels in all species. This suggests that scales can serve as a useful, non-invasive bioindicator of long-term contamination in Antarctic fishes. High accumulation of manganese, aluminium, iron and zinc is largely due to high levels in sediments associated with nearby active volcanic sites. Manganese, vanadium and aluminium showed significant positive bioaccumulation in T. bernacchii (along with non-significant positive accumulation of iron, zinc, cobalt and chromium), most likely due to greater dietary specialisation on sediment feeding benthic prey and higher trophic species. Levels of significance in bioaccumulation regressions were strongly affected by large-scale variation in the data, driven largely by individual differences in diet and/or changes in habitat use and sex differences associated with life stage and reproductive status. Increased levels of both airborne deposition and precipitation and meltwater runoff associated with climate change may be further adding to the already high levels of manganese, aluminium, iron and zinc in Antarctic Peninsula sediments. Further long-term studies are encouraged to elucidate mechanisms of uptake (especially for aluminium and iron) and possible intra- and interspecific impacts of climate change on the delicate Antarctic food web.

     

Vegetation of Barton Peninsula in the neighbourhood of King Sejong Station (King George Island,maritime Antarctic)

Plant communities were studied on Barton Peninsula around King Sejong Station on King George Island, maritime Antarctic. The objective of this study was to document the occurrence and distribution of plant assemblages to provide the bases for monitoring the effects of environmental changes and human impact on the vegetation of this area. Approximately 47% of the investigated area was covered by vegetation. Crustose lichens showed the highest mean cover (21%) among vegetation components. The total mean cover of the four dominant taxa, together with the other three major subdominant components, i.e., Usnea spp., Andreaea spp. and Sanionia georgico-uncinata, was 78.2% of the total cover of all the species. Lichen cover and species diversity increased with altitude and the time of exposure from snow. Lichens contributed substantially more to the increased species density and diversity than did bryophytes. Ten plant communities were recognized within the study area. All of them belong to the Antarctic cryptogam tundra formation; they were grouped into four subformations: fruticose lichen and moss cushion subformation, crustose lichen subformation, moss carpet subformation and moss hummock subformation. The moss turf subformation was not found on this region. The Antarctic herb tundra formation was also not found; however, the populations of both Antarctic vascular plants have rapidly expanded around Barton Peninsula in recent years, which may allow development of the Antarctic herb tundra formation in the future.