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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.

Lacustrine sediments from ice-free areas of Antarctica record both paleoecological and paleoclimatic information. Four sediment profiles (IIL1, IIL3, IIL4 and IIL9) were collected at Inexpressible Island, Ross Sea, to establish a robust late-Holocene chronology using accelerator mass spectrometry (AMS) 14C dating and geochemical and lithological analyses. The IIL1 and IIL4 sediments were strongly affected by penguin guano, and their bottom (oldest) ages were dated to 1659 and 4820 yr BP, respectively, using a Mixed Marine SoHem mode. By contrast, the organic matter of IIL3 and IIL9 sediments were predominantly sourced from aquatic microbial mats with the bottom ages of these two cores at 3179 and 2945 yr BP, respectively, based on a SHCal13 mode. The mass accumulation rates of the four sediment profiles inferred from this chronology showed peaks during ~1400–800 yr BP, corresponding to greater mean grain size and higher sand fraction ratios in the IIL3 and IIL9 profiles, suggesting a strengthened hydrodynamic effect in this period. Our results indicate a relatively warm period occurred in the study area, in accordance with an ‘optimum’ warming in the Ross Sea region. From a regional view, this warm period was also consolidated with climatic records from the western Ross Sea, most likely corresponding to a well-recognized climate perturbation known as the Medieval Climate Anomaly (MCA) in many parts of the world.

Seabirds are ideal model organisms to track mercury (Hg) through marine food webs as they are long-lived, broadly distributed, and are susceptible to biomagnification due to foraging at relatively high trophic levels. However, using these species as biomonitors requires a solid understanding of the degree of species, sexual and age-specific variation in foraging behaviors which act to mediate their dietary exposure to Hg. We combined stomach content analysis along with Hg and stable isotope analyses of blood, feathers and common prey items to help explain inter and intra-specific patterns of dietary Hg exposure across three sympatric Pygoscelis penguin species commonly used as biomonitors of Hg availability in the Antarctic marine ecosystem. We found that penguin tissue Hg concentrations differed across species, between adults and juveniles, but not between sexes. While all three penguins species diets were dominated by Antarctic krill (Euphausia superba) and to a lesser extent fish, stable isotope based proxies of relative trophic level and krill consumption could not by itself sufficiently explain the observed patterns of inter and intra-specific variation in Hg. However, integrating isotopic approaches with stomach content analysis allowed us to identify the relatively higher risk of Hg exposure for penguins foraging on mesopelagic prey relative to congeners targeting epipelagic or benthic prey species. When possible, future seabird biomonitoring studies should seek to combine isotopic approaches with other, independent measures of foraging behavior to better account for the confounding effects of inter and intra-specific variation on dietary Hg exposure.

Radionuclides including (210)Pb, (226)Ra and (137)Cs were analyzed in eight ornithogenic sediment profiles from McMurdo Sound, Ross Sea region, East Antarctica. Equilibration between (210)Pb and (226)Ra were reached in all eight profiles, enabling the determination of chronology within the past two centuries through the Constant Rate of Supply (CRS) model. Calculated fluxes of both (210)Pb and (137)Cs varied drastically among four of the profiles (MB4, MB6, CC and CL2), probably due to differences in their sedimentary environments. In addition, we found the flux data exhibiting a clear decreasing gradient in accordance with their average deposition rate, which was in turn related to the specific location of the profiles. We believe this phenomenon may correspond to global warming of the last century, since warming-induced surface runoff would bring more inflow water and detritus to the coring sites, thus enhancing the difference among the profiles. To verify this hypothesis, the deposition rate against age of the sediments was calculated based on their determined chronology, which showed ascending trends in all four profiles. The significant increase in deposition rates over the last century is probably attributable to recent warming, implying a potential utilization of radionuclides as environmental indicators in this region.

Sedimentary n-alkanoic acids are ubiquitous in the environment and their carbon isotopic composition is increasingly used to identify the source of organic matter and to reconstruct past climatic and ecological changes. Here we investigate the distribution and carbon isotope ratios of n-alkanoic acids in two sediment profiles influenced by animal excrement in Antarctica. We found that organic matter input from animal excrement is the predominate source of short- and mid-chain n-alkanoic acids in the ornithogenic sediments. Decreased δ13C values are closely related to increased excrement input of penguins and seals that occupied the study site, especially in C16 n-alkanoic acid. Long-chain (>C24) n-alkanoic acids likely originate from moss and heterotrophic microbes, and the δ13C values of C26 n-alkanoic acid were consistent with organic biomarkers and bio-elements from animal excrement. Two possible processes are suggested to explain the close relationship between C26 n-alkanoic acid δ13C values and animal excrement input. All the results indicate that the carbon isotopes of n-alkanoic acids in ornithogenic sediments can be used to indicate historical population change of penguins or seals in Antarctica.

The wide geographic distribution of penguins (Order Sphenisciformes) throughout the Southern Hemisphere provided a unique opportunity to use a single taxonomic group as biomonitors of mercury among geographically distinct marine ecosystems. Mercury concentrations were compared among ten species of penguins representing 26 geographically distinct breeding populations. Mercury concentrations were relatively low (62.00 ppm) in feathers from 18/26 populations considered. Population-level differences in trophic level explained variation in mercury concentrations among Little, King, and Gentoo penguin populations. However, Southern Rockhopper and Magellanic penguins breeding on Staten Island, Tierra del Fuego, had the highest mercury concentrations relative to their conspecifics despite foraging at a lower trophic level. The concurrent use of stable isotope and mercury data allowed us to document penguin populations at the greatest risk of exposure to harmful concentrations of mercury as a result of foraging at a high trophic level or in geographic ‘hot spots’ of mercury availability. Fil: Brasso, Rebecka L.. University Of North Carolina; Estados Unidos Fil: Chiaradia, André. Philip Island Nature Park, Research Department; Australia Fil: Polito, Michael J.. State University Of Louisiana; Estados Unidos Fil: Raya Rey, Andrea Nélida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Emslie, Steven D.. University Of North Carolina; Estados Unidos

Ornithogenic or bird-formed soils have accumulated in many coastal regions around Antarctica as a result of breeding activities by pygoscelid penguins, especially the Adelie penguin ( Pygoscelis adeliae ). These soils are often deep, range from hundreds to thousands of years old, and contain a natural archive of penguin tissues and those of their prey. In some regions, these tissues are extremely well preserved by the dry, cold environment and include complete and partial penguin mummies, feathers, bone, and eggshell. Hard parts of prey (fish bones, otoliths, and squid beaks) also commonly occur in these deposits from the penguin guano as it accumulates during soil development. Here, we review how research on these soils and the tissues they contain has progressed since they were first identified and described. These studies have provided not only valuable information on penguin occupation history with climate change since the Pleistocene, but also whole ecosystem responses to perturbations such as the ‘krill surplus’ that is hypothesized to have occurred following historic depletion of seals and whales in the 18th–20th centuries. New findings in the Ross Sea indicate how penguin occupation and abandonment cycles have progressed over millennia in relation to climate change. In addition, stable isotope analysis of δ 15 N and δ 13 C in ancient and modern Adelie penguin tissues (feathers, bone, eggshell and membrane) and guano support the ‘krill surplus’ hypothesis in showing a dietary shift from fish to krill over the past ∼200 years. Other recent studies have focused on stable isotope analyses of penguin prey remains, as well as ancient DNA and mercury analyses of penguin tissues recovered from ornithogenic soils. An analysis of fish otoliths recovered from ancient guano provide a means to investigate values of otolith carbonate δ 18 O, which correlates with other paleoclimatic records, and can be used as a proxy for changing ocean temperatures through time. In addition, measurements of total mercury (Hg) in penguin egg membrane from abandoned colonies up to 800 years old indicate significantly higher mercury levels in the past compared to modern penguins, likely due to a greater reliance on higher trophic prey prior to the proposed ‘krill surplus’. All of these studies indicate that ornithogenic soils and the natural archive of tissues they contain provide a unique means to integrate both terrestrial and marine records with ecosystem studies and climate change, past and present, in Antarctica.

Concentrations of rare earth elements (REEs) were determined in three ornithogenic sediment profiles excavated at active Adelie penguin ( Pygoscelis adeliae ) colonies in McMurdo Sound, Ross Sea, Antarctica. The distribution of REEs in each profile fluctuated with depth. REEs measured in environmental media (including bedrock, guano, and algae) and analysis on the correlations of ΣREE–lithological elements and ΣREE–bio-elements in the profiles indicated that sedimentary REEs were mainly from weathered bedrock in this area, and the non-crustal bio-genetic REEs from guano and algae were minor. Further discussion on the slopes and Ce and Eu anomalies of chondrite-normalized REE patterns indicated that a mixing process of weathered bedrock, guano and algae was the main controlling factor for the fluctuations of REEs with depth in the sediments. An end-member equation was developed to calculate the proportion of REEs from the three constituents in the sediments. The calculation functioned well in estimating bedrock-derived REEs and the magnitude of ornithogenic influence in different profiles. In general, REEs in the ornithogenic sediments showed anti bio-element patterns and thus can be used as an additional proxy to reconstruct historical penguin populations.

Biological responses to climate and environmental changes in remote polar regions are of increasing interest in global change research. Terrestrial and marine polar ecosystems have suffered from impacts of both rapid climate change and intense human activities, and large fluctuations in the population sizes of seabirds, seals, and Antarctic krill have been observed in the past decades. To understand the mechanisms driving these regime shifts in polar ecosystems, it is important to first distinguish the influences of natural forcing from anthropogenic activities. Therefore, investigations of past changes of polar ecosystems prior to human contact are relevant for placing recent human-induced changes within a long-term historical context. Here we focus our review on the fossil, sub-fossil, archaeological, and biogeochemical remains of marine vertebrates in polar sediments. These remains include well-preserved tissues such as bones, hairs and feathers, and biogeochemical markers and other proxy indicators, including deposits of guano and excrement, which can accumulate in lake and terrestrial sediments over thousands of years. Analyses of these remains have provided insight into both natural and anthropogenic impacts on marine vertebrates over millennia and have helped identify the causal agents for these impacts. Furthermore, land-based seabirds and marine mammals have been shown to play an important role as bio-vectors in polar environments as they transport significant amounts of nutrients and anthropogenic contaminants between ocean and terrestrial ecosystems.

Seabirds have substantial influence on geochemical circulation of elements, serving as a link for substance exchange between their foraging area and colonies. In this study, we investigated the elemental and carbon isotopic composition of five penguin-affected sediment profiles excavated from Ross Island and Beaufort Island in the Ross Sea region, Antarctica. Among the three main constituents of the sediments (including weathered bedrock, guano and algae), guano was the main source of organic matter and nutrients, causing selective enrichment of several elements in each of the sediment profiles. In the 22 measured elements, As, Cd, Cu, P, S, Se and Zn were identified as penguin bio-elements in the Ross Sea region through statistical analysis and comparison with local end-member environmental media such as weathered bedrock, fresh guano and fresh algae. Carbon isotopic composition in the ornithogenic sediments showed a mixing feature of guano and algae. Using a two-member isotope mixing equation, we were able to reconstruct the historical change of guano input and algal bio-mass. Compared with research in other parts of Antarctic, Arctic, and South China Sea, we found apparent overlap of avian bio-elements including As, Cd, Cu, P, Se, and Zn. Information on the composition and behavior of bio-elements in seabird guano on a global scale, and the role that bio-vectors play in the geochemical circulation between land and sea, will facilitate future research on avian ecology and paleoclimatic reconstruction.

We analyzed nitrogen and carbon stable isotope ratios and mercury (Hg) in breast feathers from three species of closely related sparrows, Saltmarsh, Seaside, and Nelson's Sparrows (Ammodramus caudacutus, A. maritimus, and A. nelsoni, respectively), to assess if trophic position and food web structure influence Hg exposure in these species. Sparrows were captured during the non-breeding season from 2006 to 2008 in North Carolina salt marshes near Wrightsville Beach, New Hanover County. Generalized linear models were used to test for the influence of species, δ15N, and δ13C on breast feather Hg. The most parsimonious model included species, δ15N, and their interaction term and explained 36% of the variation in breast feather Hg. Each species exhibited a different association between breast feather δ15N and Hg with Seaside Sparrows showing a positive correlation (r = 0.27, P = 0.03), Nelson's Sparrows a negative correlation (r = − 0.28, P = 0.01), and Saltmarsh Sparrows with no significant association. For Saltmarsh Sparrows, δ15N and Hg revealed decoupling between breast feather Hg and trophic position. Our results demonstrate that the influence of δ15N on breast feather Hg is likely indicative of geographic variation in δ15N baselines rather than trophic position.

Extralimital and extinct species of birds and mammals with either tropical or western affinities are characteristic of numerous Florida Pliocene and Pleistocene vertebrate faunas. These sites document nonanalog or disharmonious faunas, recording the association of certain genera or species that are no longer sympatric, in particular taxa now restricted to drier habitats in western North America or tropical habitats in Middle America occurring together with species still found in Florida and the southeastern United States. Extralimital or extinct taxa of western origin in Florida Plio-Pleistocene nonanalog faunas include: the mammals Antrozous , Lepus , Spermophilus , Thomomys , and Baiomys ; and the birds Gymnogyps californianus , Teratornis merriami , Aquila chrysaetos , Tympanuchus cupido , two species of Glaucidium , and Pica pica . A large influx of tropical species occurred in Florida late Blancan and early Irvingtonian sites, primarily consisting of taxa of South American origin involved in the Great American Biotic Interchange. Besides large Interchange mammals, other mammals with tropical affinities now extinct or extralimital to Florida include: the bats Desmodus archaeodaptes , Desmodus stocki , Mormoops megalophylla, Pteronotus pristinus , and Eumops underwoodi , the carnivores Leopardus pardalis , Leopardus wiedii , Panthera onca , two species of Conepatus , and Tremarctos floridanus , and the peccary Pecari . Tropical birds in Florida Plio-Pleistocene faunas include the extralimital Tachybaptus dominicus , Laterallus exilis , Jacana spinosa , Buteogallus urubitinga , Milvago chimachima , Vanellus chilensis , and Ceryle torquata ; as well as several extinct species including Titanis walleri , a chachalaca (Family Cracidae), Amplibuteo concordatus , Spizaetus grinnelli , and Cremaster tytthus . These tropical and western taxa indicate the presence of biogeographic corridors during Plio-Pleistocene glacial intervals that connected the Florida peninsula to both the arid western United States and tropical Middle America. A mosaic of desert grassland and savanna habitats intermixed with wetlands apparently extended eastward from the arid Southwest through Texas and along a southeastern corridor to the Florida peninsula. A Gulf Coast savanna corridor supporting savanna and thorn scrub habitats probably existed during glacial low sea level stands on the exposed continental shelf and coastal plain along the northern margin of the Gulf of Mexico, connecting the Florida peninsula with Mexico and Central America. The occurrence of both tropical and western taxa in some of the same faunas strongly indicates that these distributional patterns were contemporaneous and corresponded to climatic conditions and vegetational associations that no longer exist in Florida.

Stable isotope analysis ( δ 13 C and δ 15 N) is a useful tool when examining animal diets due to a general enrichment in heavier isotopes from prey tissues to the tissues of the predators consuming them. However, the amount of this enrichment, or discrimination, can vary among taxa and tissue type, limiting the use of stable isotope analysis when estimating diet composition. In this study we calculate the dietary isotopic discrimination factors of specific Pygoscelis penguin egg tissues, including eggshell, shell membrane, albumen and yolk, using a captive population of gentoo penguins fed known diets. We found that discrimination factors varied by isotope, tissue, and whether factors were calculated from whole fish or fish muscle. The observed variation in discrimination factors across tissues likely reflects differences in biochemical and metabolic processes during tissue synthesis. We validated the use of tissue discrimination factors derived in this study by independently reconstructing the diet composition of wild gentoo penguins at Cape Sherriff, Livingston Island, Antarctica using the δ 15 N values of eggshell organics and shell membrane. While eggshell organics and shell membrane from the same egg differed in raw δ 15 N values, modeling confirmed that these differences were due to tissue-specific isotopic discrimination. Furthermore, our results suggest that in 2006, female gentoo penguins at Cape Sherriff consumed a higher percentage of krill than fish during the egg-laying period.

An investigation of the effects of solvent, temperature and the bulk of the silyl and carbamate functionalities on the stereoselective synthesis of substituted vinyl carbamates from α-silyl benzyl carbamates is described.

We integrate taphonomic data on vertebrate and invertebrate paleontology, micropaleontology and palynology to explain the formation of a late Pliocene death assemblage of marine birds and fish in the “Pinecrest Sand”, Gulf Coastal Florida. Stereonet plots of orientation data on over 1500 cormorant (Phalacrocoracidae: Phalacrocorax) bones indicate that this fossil assemblage formed first from gradual accumulation of bone, shell and sediments on a barrier island beach, and second by rapid sedimentation in a quiet, back-beach setting associated with multiple episodes of breaching of the barrier. This latter event resulted in the preservation of 137 partial and complete cormorant skeletons and thousands of isolated bones that show a high angle of dip and a preferred orientation to the northeast. Invertebrate fossils exhibit taphonomic signatures characteristic of high-energy reworking with a large percentage of abraded shell fragments similar to beach deposits. Moreover, these data indicate that more than a single depositional episode caused the formation of the deposits referred to as the bird layers. Palynological evidence supports this conclusion. The pollen recovered from the deposits is highly abraded and broken and does not represent an in situ vegetational environment as compared to other deposits of this age in Florida and Georgia. The large number of cormorant and other seabird and fish remains in the bird layers appears to have been caused by a series of toxic red tides that occurred on the Gulf Coast of Florida. These events today cause die offs of large flocks of cormorants and bottom-dwelling fish similar to those recovered from the site. Palynological analysis of the sediments revealed abundant cysts of a dinoflagellate species known to produce toxic red tides. The most likely cause of the death of the cormorants and other vertebrates at this site is a toxic bloom of a variety of Pyrodinium bahamense, the thecate form of the dinoflagellate cyst Polysphaeridium zoharyi, which has a stratigraphic range from the lower Eocene to the Holocene.

Hexahydro-3a, 7a-dihydroxy-3,7,7-trimethyl-2-phenyl-4H-furo [3,2-c]pyran-4-one 6 has been obtained from the reaction between tetrahydro-4, 4-dimethyl-2-oxo-3-furanyl propanoate 4 , benzaldehyde and base. The product is the result of a modified benzilic acid rearrangement.

(−)(R,R)-2-Amino-1-(4-nitrophenyl)propan-1,3-diol 3 has been used to resolve racemic 3-hydroxy-2-methylene-3-phenylpropanoic acid 1a. Conversion of the laevorotatory enantiomer into anti and syn methyl 3-hydroxy-2-methyl-3-phenylpropanoate, 2a and 2b respectively, was achieved with Pd/H2. Correlation of the specific rotations of 2a and 2b with isomers of known configuration established the absolute configuration of 4a as R. This was confirmed independently by X-ray crystallography.

An efficient synthesis of substituted vinyl carbamates, from benzyl carbamates via the Peterson olefination is described.

An efficient synthesis of N -Acylimidazolidinones derived from α,β-unsaturated acid chlorides using DABCO as the base is described.