A survey of the terrestrial Tardigrada of the Vestfold Hills,Antarctica

A survey of the terrestrial tardigrades inhabiting growths of algae, lichens and mosses in the Vestfold Hills, Antarctica, was carried out at 11 and 35 sites during the austral summers of 1980 and 1982, respectively. In all, 24 species of plants were collected from which four genera and four species of Tardigrada were recovered. A key to the tardigrades of the area is presented. The distribution and associational patterns of the tardigrades are discussed in the context of other studies of antarctic Tardigrada.     

The inshore marine ecosystem off the Vestfold Hills,Antarctica

The planktonic, ice/water interface, and benthic communities at three sites off the coast of the Vestfold Hills, Antarctica, were examined over a complete year.The planktonic flora and fauna were composed predominantly of oceanic species with diatoms and copepods the numerically dominant groups. Primary production was largely restricted to the summer months except for epontic algae which developed in spring. The zooplankton exhibited a similar seasonal cycle but lagged some months behind that of the phytoplankton.The ice/water interface (epontic) fauna consisted of species from the plankton and benthos. Copepods were major contributors; however, two amphipod species dominated. Seasonality of the fauna in this habitat was determined by ice formation and breakout, and development of ice algae.Each of the benthic substrates supported a characteristic macrofaunal assemblage, although infaunal amphipods and tanaids were similar at each site. Infauna exhibited a distinct seasonal cycle related to that of the primary producers whereas macrofauna showed no seasonal changes in abundance.Species composition of each community in this coastal antarctic region was comparable with that of similar habitats in other antarctic coastal areas, supporting the circumpolarity of antarctic marine communities.     

Studies of viruses in penguins in the Vestfold Hills

Blood and cloacal swabs were collected from 1073 Adelie penguins (Pygoscelis adeliae) in 13 separate colonies near Davis in the Vestfold Hills, Antarctica. Three paramyxoviruses, distinct from Newcastle disease virus, were isolated from cloacal swabs obtained from penguins at three widely separated colonies. These isolates, together with others obtained from penguins in other areas of Antarctica, suggest that such viruses are widespread in antarctic penguins. Their significance in the ecology of antarctic penguins has not been determined. No evidence of infection with Newcastle disease virus or avian influenza virus was obtained during the survey.     

Plants and landscape in the Vestfold Hills,Antarctica

Maps are presented showing the recorded distribution and species density of terrestrial plants in the Vestfold Hills. The distribution, biomass and species diversity of terrestrial lithic algae, mosses and lichens is influenced positively by availability of meltwater from drift snow and by additional nutrient supply (probably N and P) near bird nest sites. The terrestrial plants are affected negatively by exposure (including sand blast) and salinity. These four factors are probably the most important environmental characteristics exercising local control over plant distribution and abundance within the limits set by temperature.Large changes in salinity, degree of exposure, water supply and nutrient supply occur across the Vestfold Hills, with the most favourable conditions generally occurring in the eastern half fairly close to the ice sheet.Plant distribution and abundance are also discussed in relation to the length of time that particular areas have been exposed as a result of ice retreat. With increasing time of exposure, plant diversity and abundance rise but subsequently fall sharply as conditions become more arid, saline, or both. This temporal sequence can be explained by considering changes in the important factors that control plant growth.     

High diversity and low specificity of fungi associated with seedless epiphytic plants

Epiphytes, which grow on other plants for support, make up a large portion of Earth's plant diversity. Like other plants, their surfaces and interiors are colonized by diverse assemblages of fungi that can benefit their hosts by increasing tolerance for abiotic stressors and resistance to disease or harm them as pathogens. Fungal communities associated with epiphytic plants and the processes that structure these communities are poorly known. To address this, we sampled seven epiphytic seedless plant taxa in a Costa Rican rainforest and examined the effects of host identity and microhabitat on external and endophytic fungal communities. We found low host specificity for both external and endophytic fungi and weak differentiation between epiphytic and neighboring epilithic plant hosts. High turnover in fungi within and between hosts and habitats reveals that epiphytic plant-associated fungal communities are highly diverse and suggests that they are structured by stochastic processes.     

Genetic variation in Antarctic populations of the moss Sarconeurum glaciale

Sixty-six isolates of the moss Sarconeurum glaciale were collected from sites in continental Antarctica at Ross Island, southern Victoria Land and the Vestfold Hills. Genetic variation within and among the populations was estimated using isozymes and random amplified polymorphic DNA (RAPD) technology. Isozyme results only reproducibly showed variation between the populations with one enzyme; RAPDs indicated significantly higher levels of genetic variability within and among the Vestfold Hills samples than in the Ross Sea region samples. A dendrogram produced from the RAPD bands suggested that the Ross Island and southern Victoria Land samples form one population, and those from the Vestfold Hills form a separate and more variable population, possibly resulting from separate colonisation events on the continent. Received: 15 March 1996 / Accepted: 1 May 1997     

Widespread occurrence of populations of the unique autotrophic ciliate Metodinium rubrum (Ciliophora: Haptorida) in brackish and saline lakes of the Vestfold Hills (eastern Antarctica)

The occurrence of the unique autotrophic ciliate Mesodinium rubrum was investigated in a suite of lakes of various salinities situated in the Vestfold Hills oasis, Princess Elizabeth Land (eastern Antarctica). M. rubrum was found to occur in all but the most hypersaline lakes in the survey but was most numerous in the more brackish lakes. Salinity and water column temperature appeared to be the most important factors controlling the occurrence and abundance of this species. Nutrient levels (phosphate and nitrate) did not appear to be important controlling factors, although their influence may have been distorted by the fact that nutrient concentrations were generally higher in the more saline lakes. The widespread occurrence of this species in brackish and saline lakes of the Vestfold Hills provides opportunities to study the ecology and possible physiological and ultrastructural adaptations to living in a high-latitude environment of this ubiquitous and important species in marine microbial food webs.     

Uncertainty of using habitat fidelity in biomonitoring based on benthic diatoms - the Raška River case study

Epilithic diatoms are frequently recommended for river biomonitoring, while much less emphasis is placed on epiphytic communities. This study considers use of epiphytic and epilithic diatom communities from the Ra?ka River in biomonitoring. A total of 212 diatom taxa were recorded in both communities. Dominant diatoms were Achnanthidium minutissimum (Kützing) Czarnecki, A. affine (Grunow) Czarnecki, A. subatomus (Hustedt) Lange-Bertalot, Amphora pediculus (Kützing) Grunow, Diatoma vulgaris Bory, Gomphonema tergestinum (Grunow) Fricke, Cocconeis placentula var. lineata (Ehrenberg) Van Heurck, Melosira varians Agardh and Navicula tripunctata (Müller) Bory. Redundancy analysis (RDA) was used to detect the relationships between diatoms, some environmental factors and sampling sites. Diatoms of the epiphytic community showed a clearly grouping in relation to the sampling sites as compared with diatoms of the epilithic community. Species common to both communities showed a similar correlation with some environmental variables (BOD, pH, NH₄⁺, TP, NO₃^? and conductivity), with three exceptions (Diatoma vulgaris, Cymbella compacta, and Encyonema silesiacum). Pearson’s correlation coefficient showed correlation between selected environmental variables and diatom indices calculated using OMNIDIA 6.2 software (TDI, IPS, CEE, GENRE, TID, SID, SHE and IDSE/5). Diatoms of the epiphytic community are more clearly clustered in relation to the sampling sites as compared with diatoms of the epilithic community. According to our results there is still “place” in biomonitoring for epiphytic community. The present study highlights the necessity of sampling both epiphytic and epilithic communities because substrate specificity could play important role in biomonitoring.     

Influence of Habitat and Climate Variables on Arbuscular Mycorrhizal Fungus Community Distribution,as Revealed by a Case Study of Facultative Plant Epiphytism under Semiarid Conditions

In semiarid Mediterranean ecosystems, epiphytic plant species are practically absent, and only some species of palm trees can support epiphytes growing in their lower crown area, such as Phoenix dactylifera L. (date palm). In this study, we focused on Sonchus tenerrimus L. plants growing as facultative epiphytes in P. dactylifera and its terrestrial forms growing in adjacent soils. Our aim was to determine the possible presence of arbuscular mycorrhizal fungi (AMF) in these peculiar habitats and to relate AMF communities with climatic variations. We investigated the AMF community composition of epiphytic and terrestrial S. tenerrimus plants along a temperature and precipitation gradient across 12 localities. Epiphytic roots were colonized by AMF, as determined by microscopic observation; all of the epiphytic and terrestrial samples analyzed showed AMF sequences from taxa belonging to the phylum Glomeromycota, which were grouped in 30 AMF operational taxonomic units. The AMF community composition was clearly different between epiphytic and terrestrial root samples, and this could be attributable to dispersal constraints and/or the contrasting environmental and ecophysiological conditions prevailing in each habitat. Across sites, the richness and diversity of terrestrial AMF communities was positively correlated with rainfall amount during the most recent growing season. In contrast, there was no significant correlation between climate variables and AMF richness and diversity for epiphytic AMF communities, which suggests that the composition of AMF communities in epiphytic habitats appears to be largely determined by the availability and dispersion of fungal propagules from adjacent terrestrial habitats.     

Fossil bivalves in marine sediments of Vestfold Hills in Eastern Antarctica

Bivalves collected in Vestfold Hills during the 55th Russian Antarctic Expedition (RAE, 2009?2010) are represented by five species. Four of them (Laternula elliptica, Thracia meridionalis, Adamussium colbecki, and Philobrya sublaevis) were collected in the sediments that filled the coastal lake terraces during the Holocene; these species are still abundant on the Antarctic shelf at present. Bivalves were found in eight samples, with L. elliptica shells and fragments thereof found in seven of those samples. The sample collected near Deep Lake had the most diverse species composition, as it contained all four species named above. Shells of named species widely occurring in present-day Antarctica were found high above sea level in the marine sediments of the oasis. This indicate to the similarity of the oasis habitats in the past and the recent marine conditions. Fragments of shells of the fifth (now extinct) species Ruthipecten tuftsensis were found in glacial–marine sediments of the Marine Plain dating back to the late Pleistocene. The present study of fossil bivalves from the late Cenozoic marine sediments in Vestfold Hills is the first of its kind in Russia.     

Variation in the ribosomal ITS-sequence of the lichens Buellia frigida and Xanthoria elegans from the Vestfold Hills,eastern Antarctica

Abstract:Thalli of the lichens Buellia frigida and Xanthoria elegans were collected from five different locations each 5–15 km apart in the Vestfold Hills, Princess Elizabeth Land, eastern Antarctica. A further collection was made from Mawson Station, Mac Robertson Land, eastern Antarctica, 660 km away. DNA was extracted from whole thalli and the ribosomal ITS region amplified by PCR using fungal specific primers. Resulting products were sequenced to gain an indication of whether or not variation was present within populations of lichen-forming fungi from continental Antarctica, and therefore of the availability of genetic resources to react to pressures such as climate change. Three genotypes ofB. frigida and two of X. elegans were detected in the Vestfold Hill collections. However, these differed by only one nucleotide position suggesting the presence of relatively little genetic variation, if the ITS region is indicative of the overall genome. Buellia frigida collected from Mawson Station had an identical ITS region sequence to the most common Vestfold Hills genotype, indicating that this species may have a low level of genetic variation across much of eastern Antarctica. In contrast, X. elegans collected from Mawson showed considerable genetic variation from the Vestfolds thalli, differing at 14·2% of nucleotide positions and had an identical ITS region sequence to an isolate from maritime Antarctica 4960 km away. Samples from the Vestfold Hills formed a distinct cluster in a phylogenetic analysis of ITS sequences from a worldwide collection of X. elegans isolates.     

The plankton community of a young, eutrophic, Antarctic saline lake

A shallow, saline lake (Rookery Lake) close to the sea and surrounded by a penguin rookery was investigated during the austral spring and summer of 1996/1997. The proximity to the sea means that the lake is likely to have been formed recently during isostatic uplift. Inputs of carbon and nutrients from the penguin rookery have rendered Rookery Lake eutrophic compared with other brackish and saline lakes in the Vestfold Hills. Chlorophyll a concentration, bacterioplankton, heterotrophic nanoflagellate and phototrophic nanoflagellate abundances were all significantly higher than in other non-enriched lakes. The high productivity created seasonal anoxia during winter and spring below ice cover. The ciliate community resembled the marine community, and was dissimilar to that seen in older saline lakes within the Vestfold Hills. Thus Rookery Lake provides valuable evidence of the impact of natural eutrophication on an Antarctic lake, as well as of the evolution of the typical microbial community which dominates the older lakes of the Vestfold Hills. Accepted: 2 May 1999     

Stream epilithic, epipelic and epiphytic diatoms: habitat fidelity and use in biomonitoring

We compared the use of epilithic, epiphytic, and epipelic diatom communities in stream biomonitoring by investigating species composition and relationships with measured water quality variables in two tributaries of the Grand River, Ontario, Canada. Although ordination showed some separation of the epilithon from other habitats, clear habitat preferences and seasonality were not identified. Canonical correspondence analysis showed that measured water quality variables explained the major gradients in the diatom data for all three habitats. The diatoms from each habitat were strongly related to alkalinity, suspended solids, biological oxygen demand and conductivity, and in addition, epipelic and epiphytic diatoms showed significant relationships with total phosphorus. It was concluded that although some species were more abundant in one habitat than the others, the community structure of the epilithic, epiphytic and epipelic habitats from these streams was not consistently different. The results indicate no apparent benefit to sampling discrete habitats for water quality monitoring using diatoms, however, the best relationship are obtained using the sum of the diatom data from all three habitats.     

Occurrence and distribution of tracheoidal elements in the Orchidaceae

Eighty-eight species of West African orchids were examined for tratheoidal elements in the root, stem, pseudobulb and leaf. Forty-three species (49%) contained tiacheoidal elements. al were epiphytic species; none of the twelve terrestrial and one epilithic/terrestrial species examined contained tracheoidal elements. Of the epiphytic species, twenty-one contained tracheoidal elements in the roots; seventeen in the stem/pseudobulb and twenty-three in the leaves.
The tracheoidal elements are similar in structure: they all possess annular, spiral, reticulate or pitted secondary wall thickenings. These elements vary in shape, size and distribution in the different species and these variations may be of some taxonomic use within the Orchidaceae.
The functions of the tracheoidal elements is not clear, but they probably provide mechanical support and also aid water -retention in the organs containing them.     

Ace Lake: three decades of research on a meromictic,Antarctic lake

Ace Lake (Vestfold Hills, Antarctica) has been investigated since the 1970s. Its close proximity to Davis Station has allowed year-long, as well as summer only, investigations. Ace Lake is a saline meromictic (permanently stratified) lake with strong physical and chemical gradients. The lake is one of the most studied lakes in continental Antarctica. Here, we review the current knowledge of the history, the physical and chemical environment, community structure and functional dynamics of the mixolimnion, littoral benthic algal mats, the lower anoxic monimolimnion and the sediment within the monimolimnion. In common with other continental meromictic Antarctic lakes, Ace Lake possesses a truncated food web dominated by prokaryote and eukaryote microorganisms in the upper aerobic mixolimnion and an anaerobic prokaryote community in the monimolimnion, where methanogenic Archaea, sulphate-reducing and sulphur-oxidizing bacteria occur. These communities are functional in winter at subzero temperatures, when mixotrophy plays an important role in survival in dominant photosynthetic eukaryotic microorganisms in the mixolimnion. The productivity of Ace Lake is comparable to other saline lakes in the Vestfold Hills, but higher than that seen in the more southerly McMurdo Dry Valley lakes. Finally, we identify gaps in the current knowledge and avenues that demand further investigation, including comparisons with analogous lakes in the north polar region.     

Changing distribution of late Quaternary terrestrial lacustrine and littoral environments in the Vestfold Hills,Antarctica

Relict marine terraces and associated boulder pavements allow the mapping of coastal environments in the Vestfold Hills and adjacent islands approximately 6000 a B.P. These structures are best developed in what were restricted tidal waters and are ascribed to sea-ice dynamics. The retreat of glacier ice, the subsequent flooding of many areas by sea water and the drainage of most of these as isostatic uplift raised the Vestfold Hills in the Holocene, have produced an immense variety of lacustrine environments as well as a diverse marine littoral. Glacial advance and retreat have occurred in the mid-late Holocene and is particularly evident adjacent to the Sørsdal Glacier.     

Survey of South Polar skuas (Catharacta maccormicki) for blood parasites in the Vestfold Hills region of Antarctica

Thin blood smears prepared from 125 South Polar skuas (Catharacta maccormicki) at breeding islands and feeding sites in the Vestfold Hills region of Antarctica between December 1999 and January 2000 did not contain hematozoa. These findings confirm results of previous smaller studies, and provide baseline data for this species.     

Trace element distributions in some saline lakes of the Vestfold Hills,Antarctica

The distributions of trace elements in Shield, Ace and Burton Lakes of the Vestfold Hills were investigated. Three aspects are discussed as follows: (1) the vertical distribution of 18 trace elements in the three lakes, (2) the behaviour of trace elements in the lakes, especially that of manganese in Shield Lake, and (3) the origin of trace elements in antarctic saline lakes.High concentrations of trace elements were found in these coastal saline lakes, when compared to open ocean water.We suggest that the peak of total extractable manganese, found at 20 m in Shield Lake, was related to the oxic/anoxic water interface brought about by microbiological activity. Solid phase manganese at the upper oxic layer may have precipitated and then reached the anoxic boundary to be there reduced to manganese ion. This dissolved manganese may then have diffused upwards to be reoxidized to a solid form. This cycle, repeated many times, may have produced the Mn profile.The alkali, alkaline earth elements and Cl were probably derived from relict seawater. Other elements were present in similar concentration ratios to those of South Polar aerosols. Residence time calculations indicate that fallout of aerosol particles, themselves derived from various sources, is capable of accounting for the measured concentrations of some trace elements in Shield Lake. This source of trace elements may be significant for other antarctic saline lakes.     

Meromixis in an antarctic fjord: a precursor to meromictic lakes on an isostatically rising coastline

Physico-chemical data and isotopic studies (utilising H¹⁴CO₃, H₂ ¹⁸O, ³H₂O) suggest that hypersaline meromixis in Ellis Fjord (Vestfold Hills, Antarctica) was initiated during the middle Holocene period, when hypersaline brine, excluded during the annual formation of sea-ice, gravitated in a density current to the bottom. The application of this contemporary information to the genesis of the meromictic lakes found today in the Vestfold Hills, suggest that their meromixis may have developed prior to isolation from the sea. Comparison of physico-chemical data from the meromictic basins of Ellis Fjord with that of the Vestfold Hills saline lake allows some determination of their evolutionary pathways initiated before, during and after isolation from the sea. Further evolution of each lake can be explained through the individual interaction between climate, the catchment size and basin morphology.     

SEASONAL,SUCCESSION OF ALGAE IN RIVERS. I. EXAMPLES FROM THE AVON,A LARGE SLOW-FLOWING RIVER1

The epipelic, epilithic and epiphytic algae in a large slow-flowing river (the Avon) situated in southern England usually exhibited a pronounced bloom during early spring probably in response, to increasing daylength. Although floods caused a reduction in the standing crop of most communities both through scouring action and possibly long-term alteration of microhabitat, they also seemed essential for the renovation of sediment and, rock substrates after periods of rapid algal growth. Because of the attachment characteristics of the predominant epiphytic species, the community attached to Cladophora remained relatively unaffected by flooding. Water velocity may have been important in determining the species composition of some communities, particularly the epiphytic associations. Nutrients probably seldom limited development, but during part of the summer competition with planktonic diatoms for silicon appeared to limit attached algae. During the summer, large scale detachment (which greatly reduced algal density) apparently correlates with a high photosynthetic rate. Algal, numbers in the plankton occasionally decreased in response to a loss of buoyancy of the predominant species.