Ornithogenic Soils Research Articles

Seabirds enrich Antarctic soil with trace metals in organic fractions

Coastal areas of Antarctica are subjected to anthropic contamination from around the world by trace metals biotransported and accumulated by seabird excrements. To explore this hypothesis, this study investigated the influence of seabirds on the contents of trace metals in soil organic fractions from Antarctica under different climatic conditions and from different parent materials. For this, soil profiles from the Maritime Antarctica region were selected based on the criteria of ornithogenesis, parent material, and climate. The contents of C, N, and selected metals (Ba, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, and Zn) were analysed in the organic matter associated with minerals (MAOM), the particulate fraction (POM), and in the total soil (MAOM + POM). The ornithogenic soils presented the highest amounts of C and N in the soil, MAOM, and POM as compared to nonornithogenic soils. Seabird activity resulted in an enrichment of Pb, Zn, and Cu. Among these biotransported metals, Cu and Zn seem to originate from natural biogenic processes in marine food chains, unlike Pb, which seems to come from anthropogenic sources. The soils developed from igneous rocks presented higher amounts of Ba, Co, Cu, Fe, Mn, and Sr in the soil, MAOM, and POM than soils from sedimentary rocks. The climate had no clear effect on most metals. Hence, seabirds enrich soils, MAOM, and POM with Cu, Zn, and Pb, whereas the amounts of Ba, Co, Cr, Fe, Mn, Ni, and Sr are mainly lithogenic, associated with the parent material. Monitoring biotransported trace metals in ornithogenic soils is of great importance, since they can create environmental toxicity to terrestrial plants and animals and can influence the food chain in the coastal areas of Antarctica.

Phosphatization under birds' activity: Ornithogenesis at different scales on Antarctic Soilscapes

Extensive areas of penguins’ nesting (Pygoscelis sp.), on ice-free areas, account for vast deposits of organic matter-rich guano in maritime Antarctica. One such area, at Harmony Point, currently houses different penguin colonies with extensive and unique ornithogenic soils, where phosphatization is the key soil-forming process. We sought to enhance the knowledge of phosphatization process, products, cycles, and phosphorus (P) forms in these unusual soils. We compared ornithogenic and non-ornithogenic soils, based on advanced chemical, micromorphological and mineralogical analyses of samples of guano and phosphate biocrusts, complete with P and OM fractionation. Ornithogenic soils have the organic P-pool as the largest phosphorous compartment, followed by varying P-Ca forms. In contrast, soils unaffected by phosphatization showed a high inorganic P-pool. Penguin guano is enriched with P, Ca, K, Cu, Zn, C and N. The phosphatic biocrusts are composed of struvite and hydroxyapatite, forming a gradient of phosphate forms. We recognized three different phosphatization environments, namely (i) present-day marine birds’ rookeries, (ii) adjacent zone of rookeries and (iii) abandoned rookeries. Geomorphological evolution of the coastal areas, by Holocene glacier retreat, resulted in the changing location of penguin colonies, resulting in a larger area and varying ages of phosphatization, forming ornithogenic soils with contrasting evolution degrees. Abandoned areas have greater vegetation growth, with higher diversity.

Content of Trace Elements in Soils of Eastern Antarctica: Variability Across Landscapes.

Although Antarctica is considered one of the most pristine areas on Earth, an accelerating human presence in this remote continent, such as scientific operations and functioning of numerous scientific stations, logistics, and tourism activities, has increased the risks of environmental impacts in recent decades. During the 63rd Russian Antarctic expedition, 42 samples from topsoil horizons were collected from Larsemann Hills, Mirny station, and Fulmar Island, Eastern Antarctica. The purpose of this work was to analyze the accumulation levels 8 trace elements and to assess possible environmental risks associated with contamination of Antarctic soils. Various human activities have been found to be responsible for increase of metal levels in studied Antarctic environments. Our study also revealed a specific role of ornithogenic factor and moss cover in distribution of contaminants in severe conditions of Eastern Antarctica soils. Ornithogenic soils were characterized by higher rates of accumulation of some trace metals and metalloids (especially zinc and copper) compared with other investigated "pristine" sites without significantly visible traces of guano inputs. In general term, obtained geoaccumulation index for trace elements in all samples were under or slightly above the 0 level, indicating low to moderate pollution of the studied soils. Results of principal component analysis revealed the necessity for further detailed research on interactions of trace metals with soil organic matter for better understanding of their biogeochemistry in the Antarctic environment. Although most of contaminated sites were found in anthropogenically affected areas, accumulation of some elements in guano-derived and moss materials were associated with higher values for soil pollution indices in natural soils, as well.

Clay mineralogy and micropedology of phosphate-rich soils from Lions Rump, Maritime Antarctica

Micropedology studies by description of scanning electron microscopy images and electron micropobre analysis combined with field soil description, mineralogical, physical, and chemical laboratory analyses, can furnish valuable information about soil genesis in polar regions. The present study was carried out at Lions Rump (King George Island, Maritime Antarctica), where six pedons were selected to represent the main soil types found in the local ice-free areas, varying from bare (without vegetation) to well-vegetated ornithogenic soils, with high phosphate and organic matter content. Each pedon was described and sampled for mineralogical, micromorphological and microchemical studies, complemented by chemical and physical analyses. Phosphatization is the main forming process in these soils and two types of ornithogenic soils could be distinguished: Acid pH ornithogenic soils and Neutral pH ornithogenic soils. Phosphate-rich, deep, acid pH ornithogenic soils are the most developed soils and occur associated with abandoned penguin rookeries, with well-crystalline Al-phosphates (taranakite). Soils recently occupied by penguins have neutral pH and absence of crystalline phosphate minerals, although they are also rich in exchangeable P. Phosphate are found as illuvial coatings, infillings, reacting alteration cortex of clasts or compound the micromass of the aggregates. Although the microstructures of Lions Rump soils are related to frost-action, the phosphatization forming a particular well-developed rounded aggregates, under strong biological influence. The ornithogenesis depends on the time of exposure to birds' influence and decomposition stage of guano.

Biological and physicochemical properties of the nests of White Stork Ciconia ciconia reveal soil entirely formed, modified and maintained by birds

The physiological and behavioural activities of animals have far-reaching impacts on the characteristics and functioning of soil. This includes vertebrates, which are capable of modifying the physicochemical and biochemical properties of soil. To date, however, no species is known to be responsible for the entire process of soil formation, modification and maintenance. Large-bodied birds build nests which they then use for several years or even decades. During nest construction or renovation, birds gather and transport to the nesting site organic and mineral matter that includes tree branches of various sizes, twigs, turf, straw and hay. Over time, during subsequent breeding events, adult birds supply further loads of organic matter to the nest, such as food remains, excrement, pellets, feathers, egg shells and other materials. Taking the White Stork Ciconia ciconia as an example, we have shown that the materials deposited in the nests of large-bodied birds gradually produce ornithogenic soils over the years, with distinguishable layers having different physicochemical characteristics and biochemical activities. The tested nesting substrate met the criteria for ornithogenic material; the layers had appropriate thickness and phosphorus pentoxide (P2O5) content. Results of the study indicates that the material contained in White Stork nests have the characteristics of Histosols. Moreover, such nests harbour assemblages of fungi and arthropods that contain species typical of soil mycobiota and fauna, respectively. This study is the first to describe a soil that is formed, modified and maintained entirely by vertebrates and is physically isolated from the ground. Our results highlight the fact that the nests of large birds are unique structures in ecosystems and provide a habitat for a rich and diverse assemblage of organisms.

Hydrogeochemistry and chemical weathering in a periglacial environment of Maritime Antarctica

Recent pedological investigation indicated that the presence of sulfides and additions of seabird guano in Maritime Antarctica accelerates the weathering process, but chemical weathering remains little studied, underestimated and underdiagnosed in cold environments. The present work evaluates characteristics of soils and hydrogeochemical processes in Barton Peninsula, a typical periglacial environment of Maritime Antarctica. Four pedons were selected, described, sampled and classified according to the U.S. Soil Taxonomy. Soil morphological, physical and chemical properties were analyzed. Fifty eight surface water samples were collected and analyzed. Samples were filtered, acidified and analyzed (Al, Ca, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, S, Si and Zn) by ICP-OES after the appropriate treatments. We identified four different water groups: i) calcium and magnesium bicarbonate waters on non-sulfated substrates; ii) acidic sodium sulfate or magnesium calcium sulfate waters in sulfate substrates; iii) neutral alkaline waters on phosphatic substrates; iv) sodium hyperchloride alkaline waters in coastal marine areas. The hydrogeochemical composition can be predicted by lithology, landform and bird nesting density. Higher concentrations of metals in running waters indicate the process of sulfide oxidation. Our results show that seabirds activity promotes a sea-land bio-transfer of nutrients resulting in ornitheutrophication, identified by positive hydrogeochemical anomaly (high nutrients) in soils and waters. Sulfated and ornithogenic soils present deeper weathering (sulfurization and phosphatization processes), which cannot be underestimated. The assessment of hydrogeochemical background is a suitable tool for preservation of terrestrial ecosystems in this part of Antarctica.

LA RICOLONIZZAZIONE DELL’ANTARTIDE: STORIE DI PINGUINI E FOCHE, SENTINELLE DEI CAMBIAMENTI CLIMATICI NEGLI ULTIMI 10 MILA ANNI

The re-colonization of Antarctica: stories of penguins and seals, sentinels of climate change in the last ten thousand years. During the Late Pleistocene the Antarctic glacial system expanded and advanced on the coastal margin of the continent forcing penguins, seals and other animals nesting in the deglaciated areas to migrate toward refuge areas located at northern latitudes. The deglaciation that followed the last glacial maximum, in the Ross Sea area, was accomplished around 8000 years ago, freeing the Antarctic coasts that were re-colonized by Adélie penguins and elephant seals. These two species have coexisted, even alternating, in the deglaciated areas of the coastal strip for several millennia. In the ornithogenic soils of the abandoned penguin colonies and in the breeding sites of the elephant seals, recently discovered on the Holocene raised beaches, a precious heritage of organic remains is preserved, allowing us to study different aspects of recent environmental history. The phases of colonization and coexistence between penguins and elephant seals are very complex and reflect the climatic-environmental variations that have characterized the Antarctic scenario for several thousand of years. Penguins and elephant seals, sensitive sentinels of the Antarctic ecosystem, are now playing an important role in the Southern Ocean scenario, interpreting the dramatic role of bellwether of climate change.

Late Holocene variation in the Hard prey remains and stable isotope values of penguin and seal tissues from the Danger Islands, Antarctica

Ornithogenic soils in Antarctica provide a biological archive of the occupation history and trophic ecology of penguins and other marine species over geological timescales. Hard prey remains and predator tissues, which are well preserved in ornithogenic soils, can act as paleoecological proxies of past environmental conditions. Here we examine ornithogenic soils from an active colony of Pygoscelis spp. penguins on Platter Island in the Danger Islands Archipelago along the northeastern side of the Antarctic Peninsula. We radiocarbon dated penguin tissues from excavated ornithogenic soils and parameterized an age-depth model of penguin occupation history. Hard prey remains were enumerated and recovered Pygoscelis spp. penguin and Antarctic fur seal (Arctocephalus gazella) tissues were analyzed for stable isotopes carbon (δ13C) and nitrogen (δ15N) analysis. The oldest recovered ornithogenic soils at Platter Island date to 502–653 years BP and coincide with the start of a period of increased warming and glacial discharge in the northeastern Antarctic Peninsula. Penguin tissues δ15N values increased between the oldest and youngest dated ornithogenic soils but seal tissues did not. This may indicate that the trophic level of penguins, but not seals, has increased over time, a hypothesis supported by the concurrent increase in the hard prey remains of fish and squid taxa common to penguin diets recovered from ornithogenic soils. Future studies of ornithogenic soils in the Danger Islands Archipelago are warranted to test this hypothesis and assess the potential confounding effects of varying ecosystem isotopic baselines and penguin species composition over time.

Soil indicators of bird activity in the temperate climatic zone – A case‐study

AbstractThe importance of birds to pedogenesis and their impact on soil characteristics is a long‐standing topic of research. For this reason, the ornithogenic soils (avian soils) are distinguished as a separate category in some soil classifications. The continuous progress of knowledge on and changes in the management of the Earth's resources demand constant updating of definitions and classification criteria in various fields of environmental sciences. A search of the literature revealed few studies that examine the properties of bird soils in the temperate climate zone. This paper focuses on ornithogenic material: grit and bones deposited in the topsoil. Although areas covered by such soils are limited to 1–100 ha, they are found in high abundance in Europe and Asia. The surface horizon of the soil examined in the current study in Poznań, Poland, contained ample ornithogenic material; however, the soil's phosphorus content was remarkably low. Therefore, the analysed soil may not be considered as an ornithogenic soil, nor can it be attributed to the ornithic supplementary qualifier provided by the World Reference Base (WRB). The case study presented here exemplifies that soils containing ornithogenic material but lacking phosphorous compounds may occur in the temperate climate zone. Therefore, we conclude that ornithogenic material is the only permanent indicator of the existence of large groups of birds in non‐polar climate zones.

Orthophosphate enhances N2O production from aerobic hydroxylamine decomposition: implications to N2O emissions from nitrification in ornithogenic and manure-fertilized soils

Soils affected by animal wastes have simultaneously high N and P contents. Despite the reports of high nitrous oxide (N2O) emissions in such environments, the role that P plays in N2O dynamics has not yet been systematically investigated. Here, we report the enhancement effect of orthophosphate (PO43−-P) abundance on N2O yields from abiotic NH2OH decomposition, which may have substantial implications to N2O emissions from nitrification in such P-rich soils. The axenic cultures of Nitrosomonas europaea, an ammonia-oxidizing bacterium previously reported to leak NH2OH, exhibited significantly higher N2O yields when incubated at higher PO43−-P concentrations. As NH4+-to-NO2− turnover and growth rates were unaffected even at the highest PO43−-P concentration examined, the abiotic interaction between extracellularly released NH2OH and PO43−-P was the most plausible mechanism of enhanced N2O emission in these nitrifier cultures. This proposed mechanism was supported by the results of abiotic NH2OH incubation whereby higher PO43−-P concentration resulted in higher N2O yield. Orthophosphate enhancement of NH2OH-to-N2O turnover was then simulated with addition of 5 μmol NH2OH to an ornithogenic soil with high PO43−-P content (23.9 ± 6.7 g/kg wet soil) and active nitrification activity after sterilization. The N2O yield, 69.0 ± 4.6%, was significantly higher than the N2O yields for other examined soils with lower PO43−-P contents (0–1.94 g/kg wet soil), and the PO43−-P contents of the examined soils exhibited strong correlation with the N2O yields. These findings suggest that N2O production from nitrification via abiotic turnover of released NH2OH may be a consequential mechanism of N2O emissions in PO43−-P-rich soils.

Application of δ15N to trace the impact of penguin guano on terrestrial and aquatic nitrogen cycles in Victoria Land, Ross Sea region, Antarctica

Penguin colonies in Antarctica offer an ideal “natural laboratory” to investigate ecosystem function and the nitrogen (N) cycle. This study assessed the spatial distribution of penguin-derived N from guano and quantitatively assessed its impact on plant N utilization strategies in Victoria Land, Ross Sea region, Antarctica. Soil, moss, and aquatic microbial mats were collected inside and outside an active Adélie penguin (Pygoscelis adeliae) colony and analyzed for δ15N of total and inorganic nitrogen (NH4+-N and NO3−-N). The soil total nitrogen (TN), NH4+-N, and NO3−-N concentrations, as well as their δ15N values were significantly higher in guano-impacted areas than those in guano-free areas, verifying that guano is an important N source at and near penguin colonies. However, even far from the penguin colonies, soil δ15N values resembled those in penguin colonies, suggesting strong spatial impacts of penguin-derived N. The moss impacted by guano was more enriched in δ15N than in guano-free areas. The δ15N values of NH4+-N and NO3−-N in soils covered with moss revealed that the moss might prefer inorganic N in the absence of guano, while the dissolved organic N would become an important source for moss growing on ornithogenic soils. Aquatic microbial mat samples near penguin colonies were 15N-enriched, but 15N-depleted at upland sites.

Transformation of sulfur species in lake sediments at Ardley Island and Fildes Peninsula, King George Island, Antarctic Peninsula

In Antarctica, penguins transport sulfur and other bio-elements in the form of guano from marine to terrestrial environments where they become deposited in ornithogenic soils and sediments, including lake or pond systems. Transformation of sulfur species in these terrestrial and aquatic deposits, however, has rarely been studied. Here, we used the cold diffusion method to analyze various sulfur species in a lake deposit of ornithogenic sediment core (C1) and a pristine lake sediment core (C2), collected from Ardley Island and Fildes Peninsula, Antarctic Peninsula, respectively. The total organic carbon, total phosphorus, total nitrogen and various sulfur species in C1 were more fluctuant and much higher than those in C2, indicating a primary source from penguin guano. In core C1, organic sulfur (Org-S) was the main form of sulfur, and sulfate (SO42−) was the main form of inorganic sulfur. The acid volatile sulfur (AVS) in C1 was much higher than pyrite sulfur (CRS). In the pristine lake sediment core C2, Org-S and SO42− were the main sulfur species. CRS was the primary form of reduced inorganic sulfur in C2 sediments in contrast to the AVS in C1, indicating that AVS had been effectively transformed into CRS in C1. Our results demonstrate that the high levels of organic matter in C1 likely limited the transformation of AVS to CRS.

Holocene occupation history of pygoscelid penguins at Stranger Point, King George (25 de Mayo) Island, northern Antarctic Peninsula

We report additional fossil evidence for pygoscelid penguins breeding on King George (25 de Mayo) Island, South Shetland Islands, in the Holocene beginning at ~7000 cal. yr BP. This evidence comes from a raised marine beach deposit formerly studied and described as Pingfo I at Stranger Point, Potter Peninsula. We relocated and exposed deposits at this site and recovered additional samples of penguin bones from five stratigraphic beds that are redescribed here. Most of these bones are from juvenile penguins and exhibit little or no wear indicating minimal transport to the beach deposits. Some of the bones are developed enough to be identifiable to Adélie ( Pygoscelis adeliae), Gentoo ( Pygoscelis papua), and Chinstrap ( Pygoscelis antarctica) penguins, indicating that all three species were breeding at Stranger Point from ~7320 to 4865 cal. yr BP. This breeding occupation corresponds with the first warming and deglaciation that occurred in the northern Antarctic Peninsula by this time and ends with the onset of reglaciation of the Peninsula. At least 31 abandoned penguin mounds and ornithogenic soils also were located and sampled at Stranger Point and indicate that the current occupation of this area by all three pygoscelid penguins dates no older than ~535 cal. yr BP. The absence of ornithogenic soils from earlier Holocene breeding was probably due to glacial activity and soil solifluction during periods of warming in the mid to late Holocene.

Soil-landscape interplays at Harmony Point, Nelson Island, Maritime Antarctica: Chemistry, mineralogy and classification

Soils and landforms of Nelson Island remain one of the least studied in the South Shetlands Archipelago, despite that it is one of the oldest ice-free areas and is strongly vegetated. In this paper, we examine the main processes and factors of soil formation at Harmony Point and the relation of soils to landforms, vegetation and lithology.To achieve the goals, 26 pedons were collected and studied from a 4 km2 ice-free area at Harmony Point (S62°18′; W059°10′) on the southern area of Nelson Island (Maritime Antarctica). The soils were sampled on all representative local landforms, including three levels of uplifted marine terraces up to cryoplanated plateau, waterlogged depressions, rock felsenmeer, debris slopes and patterned ground, and a paraglacial border of the ice cap (270 m a.s.l). Sampling along the cryoplanated plateau was carried out along a gradient extending inland from the margins of the Ice Cap; and sampling of the marine terraces was performed along a chronosequence under varying bird-nesting influence and age. The main pedogenetic processes observed in this area are marked phosphatization, melanization from the accumulation of organic matter, and cryoturbation. Soil development varies from weakly developed, shallow, stony and cryoturbated to well-developed and organic-rich, phosphate soils with colors ranging from grayish to brown. The mineralogical composition of the clay fraction contains secondary minerals, indicating the active role of chemical weathering. Ornithogenic soils have mature phosphate minerals such as vivianite and taranakite, as well as poorly crystalline leucophosphite. Intensively cryoturbated soils are underlain by permafrost and are classified as Typic Haploturbels; polygonal soils are widespread on the cryoplanated plateau. Areas without permafrost were classified as Typic Gelorthents. Phosphatization is a dominant soil-forming process in this area and is associated with past and present-day guano accumulation by bird nesting and has led to the the development of deeper Ornithogenic Haplorthels. The ornithogenic soils occur at different topographic levels on the cryplanated platform and marine terraces. High P concentrations can be used as a proxy of the past nesting birds' activities, with far-reaching implications, especially with regards to vegetation growth and microbial activity and diversity.

Ornithogenic soils on basalts from maritime Antarctica

Large amounts of organic matter deposited by marine birds, especially penguins, accumulate on ice-free areas of maritime Antarctica during the short austral summer. The well-known ornithogenic soils of this region are unique in Antarctica and represent important sites where phosphatization is the main soil-forming process. Most recent studies in ornithogenic soils of maritime Antarctica were conducted on andesitic areas, and no reports are available about ornithogenic soils on basaltic intrusion. The purpose of this study was to report the main chemical, physical, and mineralogical characteristics of ornithogenic soils on basaltic intrusion of Barrientos, and evaluate the effects of different nesting bird species and altitude. The amount of Mehlich-extractable P indicates a close interaction between guano and underlying soils, with different end products depending on altitude, weathering degree and nesting bird species. In the soil collected from the giant petrel's nest, the intensity of organic deposition was much lower. The lower means of Mehlich-extractable P, total organic carbon and total nitrogen in Barrientos Island showed the little influence of marine birds when compared to King George Island. On the other hand, the means of exchangeable Ca and Mg were higher due to the basaltic composition of the regional volcanoes, contrasting with the andesites, which are the commonest rock type in maritime Antarctica. Thus, the soil characteristics of the Barrientos Island are influenced by both parent material and phosphatization.

Direct and Indirect Effects of Penguin Feces on Microbiomes in Antarctic Ornithogenic Soils.

Expansion of penguin activity in maritime Antarctica, under ice thaw, increases the chances of penguin feces affecting soil microbiomes. The detail of such effects begins to be revealed. By comparing soil geochemistry and microbiome composition inside (one site) and outside (three sites) of the rookery, we found significant effects of penguin feces on both. First, penguin feces change soil geochemistry, causing increased moisture content (MC) of ornithogenic soils and nutrients C, N, P, and Si in the rookery compared to non-rookery sites, but not pH. Second, penguin feces directly affect microbiome composition in the rookery, not those outside. Specifically, we found 4,364 operational taxonomical units (OTUs) in 404 genera in six main phyla: Proteobacteria, Actinobacteria, Gemmatimonadetes, Acidobacteria, Chloroflexi, and Bacteroidetes. Although the diversity is similar among the four sites, the composition is different. For example, penguin rookery has a lower abundance of Acidobacteria, Chloroflexi, and Nitrospirae but a higher abundance of Bacteroidetes, Firmicutes, and Thermomicrobia. Strikingly, the family Clostridiaceae of Firmicutes of penguin-feces origin is most abundant in the rookery than non-rookery sites with two most abundant genera, Tissierella and Proteiniclasticum. Redundancy analysis showed all measured geochemical factors are significant in structuring microbiomes, with MC showing the highest correlation. We further extracted 21 subnetworks of microbes which contain 4,318 of the 4,364 OTUs using network analysis and are closely correlated with all geochemical factors except pH. Our finding f penguin feces, directly and indirectly, affects soil microbiome suggests an important role of penguins in soil geochemistry and microbiome structure of maritime Antarctica.

Geochemical and biotic factors influencing the diversity and distribution of soil microfauna across ice-free coastal habitats in Victoria Land, Antarctica

Soils in Antarctica support simple but unique biological assemblages in one of the most extreme terrestrial habitats on Earth. Among terrestrial fauna, microscopic invertebrates (nematodes, rotifers and tardigrades) are the most abundant and diverse, but the paucity of surveys still limits a more thorough understanding of their diversity and distribution patterns. To address this gap in knowledge, we conducted a survey across soil environments with differing biogeochemical characteristics (i.e., fellfields, moss communities, wetlands, and ornithogenic soils) at Edmonson Point. Our primary objective was to identify local diversity and drivers of distribution patterns of soil microfauna assemblages at the species level for all phyla. Presence of a broad range of soil habitats supported abundant and diverse microfauna of 24 species, including 18 rotifers, 4 nematodes, and 2 tardigrades. While nematode and tardigrade fauna were generally consistent with previous reports in the region, rotifers consisted mostly of bdelloids, newly-recorded and likely endemic species. Bdelloid rotifers were generally the most abundant followed by nematodes and tardigrades in similar numbers, with very patchy distributions and only nematodes found across all soil habitats. The type of soil environment was the most significant predictor of species distributions, with the richest and most abundant microfauna found in moist soils associated with cryptogamic vegetation and the poorest in dry fellfields and ornithogenic soils. Species distributions were also highly variable within particular environments and were related primarily to moisture, nutrients and organic matter, but availability and quality of food resources was the major underlying driver. Given the exceptionally wide range of terrestrial environments, Edmonson Point represents one of the most important biodiversity hot-spots for microfauna in the Ross Sea region, emphasizing its outstanding ecological importance and conservation value.

Pathogenic potential of environmental resident fungi from ornithogenic soils of Antarctica

We assessed the diversity of cultivable fungi in the ornithogenic soil nests of bird species like Phalacrocorax atriceps, Macronectes giganteus, Pygoscelis antarcticus, and Pygoscelis papua in the Antarctic islands. From 481 fungi isolated at 15 °C, only 50 displayed growth at 37 °C, and were identified as 14 species of 15 genera. Aspergillus fumigatus, Penicillium chrysogenum, and Rhodotorula mucilaginosa were the most abundant species obtained. Fifty taxa grew at 40 °C; displayed haemolytic and phospholipase activities; produced tiny spores, capsule, and melanin; showed growth at different pH; and showed resistance to amphotericin B. Interestingly, the minimum inhibitory concentration of amphotericin B increased by 5–10 fold for some A. fumigatus isolates after phagocytosis by amoeba. Our results show relations among fungal community compositions present in Antarctic ornithogenic soil and their pathogenic risk to humans in vitro. As the Antarctica Peninsula is a major region of the planet affected by global climate changes, our results, though preliminary, raise concerns about the dispersal of potential pathogenic microbes present in Antarctic substrates by wild birds, which can fly great distances and spread potential pathogens mainly to South America and Oceania.

Trace element content in soils of the King George and Elephant islands, maritime Antarctica

ABSTRACTTrace element concentrations were studied in soils of the King George and Elephant islands in the maritime part of West Antarctica. The lowest concentrations of Cu, Pb, Cd, Zn, Ni and Mn were typical for the pristine soil of Elephant Island. The highest concentrations of these elements were found in the Fildes Peninsula and revealed the influence of human activities in the area of the Bellingshausen station and adjacent waste disposal sites. Ornithogenic soils of the Fildes Peninsula have shown low concentrations of Cd and As. Using geoaccumulation indexes, all the pristine soils of King George and Elephant islands and ornithogenic soils of the Fildes Peninsula were classified as unpolluted; the human-affected soils were mainly identified as moderately polluted. Obtained data can be used as background concentration levels for further researches.

Genome content, metabolic pathways and biotechnological potential of the psychrophilic Arctic bacterium Psychrobacter sp. DAB_AL43B, a source and a host of novel Psychrobacter-specific vectors

Psychrobacter sp. DAB_AL43B, isolated from ornithogenic soil collected on the Arctic island of Spitsbergen, is a newly sequenced psychrophilic strain susceptible to conjugation and electrotransformation. Its genome consists of a circular chromosome (3.3 Mb) and four plasmids (4.4–6.4kb). In silico genome mining and microarray-based phenotypic analysis were performed to describe the metabolic potential of this strain and identify possible biotechnological applications. Metabolic reconstruction indicated that DAB_AL43B prefers low-molecular-weight carboxylates and amino acids as carbon and energy sources. Genetic determinants of heavy-metal resistance, anthracene degradation and possible aerobic denitrification were also identified. Comparative analyses revealed a relatively close relationship between DAB_AL43B and other sequenced Psychrobacter species. In addition, the plasmids of this strain were used as the basis for the construction of Escherichia coli–Psychrobacter spp. shuttle vectors. Taken together, the results of this work suggest that DAB_AL43B is a promising candidate as a new model strain for studies on Psychrobacter spp.