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Sample records for marine antarctic ectotherms

  1. Climate-dependent evolution of Antarctic ectotherms: An integrative analysis

    Science.gov (United States)

    Pörtner, Hans O.

    2006-04-01

    The paper explores the climate-dependent evolution of marine Antarctic fauna and tries to identify key mechanisms involved as well as the driving forces that have caused the physiological and life history characteristics observed today. In an integrative approach it uses the recent concept of oxygen and capacity limited thermal tolerance to identify potential links between molecular, cellular, whole-organism, and ecological characteristics of marine animal life in the Antarctic. As a generalized pattern, minimization of baseline energy costs, for the sake of maximized growth in the cold, appears as one over-arching principle shaping the evolution and functioning of Antarctic marine ectotherms. This conclusion is supported by recent comparisons with (sub-) Arctic ectotherms, where elevated levels of energy turnover result at unstable, including cold temperatures, and are related to wide windows of thermal tolerance and associated metabolic features. At biochemical levels, metabolic regulation at low temperatures in general, is supported by the cold compensation of enzyme kinetic parameters like substrate affinities and turnover numbers, through minute structural modifications of the enzyme molecule. These involve a shift in protein folding, sometimes supported by the replacement of individual amino acids. The hypothesis is developed that efficient metabolic regulation at low rates in Antarctic marine stenotherms occurs through high mitochondrial densities at low capacities and possibly enhanced levels of Arrhenius activation energies or activation enthalpies. This contrasts the more costly patterns of metabolic regulation at elevated rates in cold-adapted eurytherms. Energy savings in Antarctic ectotherms, largely exemplified in fish, typically involve low-cost, diffusive oxygen distribution due to high density of lipid membranes, loss of haemoglobin, myoglobin and the heat shock response, reduced anaerobic capacity, large myocytes with low ion exchange activities

  2. UV radiation in marine ectotherms: Molecular effects and responses

    International Nuclear Information System (INIS)

    Dahms, Hans-U.; Lee, Jae-Seong

    2010-01-01

    This review summarizes current knowledge on ultraviolet radiation (UVR)-induced cellular and molecular damage in marine ectotherms (invertebrates and fish). UVR impairs sperm motility, reduces fertilization, and causes embryo malformation that in turn affects recruitment and therefore the sustainability of natural populations. The direct molecular effects of UVR are mediated by absorption of certain wavelengths by specific macromolecules and the dissipation of the absorbed energy via photochemical reactions. Most organisms have defense mechanisms that either prevent UVR-induced damage, or mechanisms that repair the damage. Photoprotective pigments, antioxidant defense compounds, and cell cycle development genes are some of the molecules involved in UVR defense. Photoenzymatic repair and nucleotide excision repair are the two primary DNA repair systems in marine ectotherms. We anticipate that toxicogenomic studies will gain importance in UVR research because they can elucidate the primary processes involved in UVR damage and the cellular response to this damage.

  3. Upper temperature limits of tropical marine ectotherms: global warming implications.

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    Khanh Dung T Nguyen

    Full Text Available Animal physiology, ecology and evolution are affected by temperature and it is expected that community structure will be strongly influenced by global warming. This is particularly relevant in the tropics, where organisms are already living close to their upper temperature limits and hence are highly vulnerable to rising temperature. Here we present data on upper temperature limits of 34 tropical marine ectotherm species from seven phyla living in intertidal and subtidal habitats. Short term thermal tolerances and vertical distributions were correlated, i.e., upper shore animals have higher thermal tolerance than lower shore and subtidal animals; however, animals, despite their respective tidal height, were susceptible to the same temperature in the long term. When temperatures were raised by 1°C hour(-1, the upper lethal temperature range of intertidal ectotherms was 41-52°C, but this range was narrower and reduced to 37-41°C in subtidal animals. The rate of temperature change, however, affected intertidal and subtidal animals differently. In chronic heating experiments when temperature was raised weekly or monthly instead of every hour, upper temperature limits of subtidal species decreased from 40°C to 35.4°C, while the decrease was more than 10°C in high shore organisms. Hence in the long term, activity and survival of tropical marine organisms could be compromised just 2-3°C above present seawater temperatures. Differences between animals from environments that experience different levels of temperature variability suggest that the physiological mechanisms underlying thermal sensitivity may vary at different rates of warming.

  4. Extremophiles in an Antarctic Marine Ecosystem

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    Iain Dickinson

    2016-01-01

    Full Text Available Recent attempts to explore marine microbial diversity and the global marine microbiome have indicated a large proportion of previously unknown diversity. However, sequencing alone does not tell the whole story, as it relies heavily upon information that is already contained within sequence databases. In addition, microorganisms have been shown to present small-to-large scale biogeographical patterns worldwide, potentially making regional combinations of selection pressures unique. Here, we focus on the extremophile community in the boundary region located between the Polar Front and the Southern Antarctic Circumpolar Current in the Southern Ocean, to explore the potential of metagenomic approaches as a tool for bioprospecting in the search for novel functional activity based on targeted sampling efforts. We assessed the microbial composition and diversity from a region north of the current limit for winter sea ice, north of the Southern Antarctic Circumpolar Front (SACCF but south of the Polar Front. Although, most of the more frequently encountered sequences  were derived from common marine microorganisms, within these dominant groups, we found a proportion of genes related to secondary metabolism of potential interest in bioprospecting. Extremophiles were rare by comparison but belonged to a range of genera. Hence, they represented interesting targets from which to identify rare or novel functions. Ultimately, future shifts in environmental conditions favoring more cosmopolitan groups could have an unpredictable effect on microbial diversity and function in the Southern Ocean, perhaps excluding the rarer extremophiles.

  5. Ultraviolet radiation response of two heterotropy Antarctic marine bacterial

    International Nuclear Information System (INIS)

    Hernandez, Edgardo A.; Ferreyra, Gustavo A.; Mac Cormack, Walter P.

    2004-01-01

    Two Antarctic marine bacterial strains, were exposed to different irradiance of ultraviolet (UV) solar radiation using several experimental protocols and interferential filters. Results showed that both, UV-A and UV-B radiation produce deleterious effects on two tested bacterial strains. The mortality values under UVB treatments were higher than those observed under UVA treatments. UVvi strain proved to be more resistant to UV radiation than the UVps strain. (author) [es

  6. Physiological basis for high CO2 tolerance in marine ectothermic animals: pre-adaptation through lifestyle and ontogeny?

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    M. Bleich

    2009-10-01

    Full Text Available Future ocean acidification has the potential to adversely affect many marine organisms. A growing body of evidence suggests that many species could suffer from reduced fertilization success, decreases in larval- and adult growth rates, reduced calcification rates, and even mortality when being exposed to near-future levels (year 2100 scenarios of ocean acidification. Little research focus is currently placed on those organisms/taxa that might be less vulnerable to the anticipated changes in ocean chemistry; this is unfortunate, as the comparison of more vulnerable to more tolerant physiotypes could provide us with those physiological traits that are crucial for ecological success in a future ocean. Here, we attempt to summarize some ontogenetic and lifestyle traits that lead to an increased tolerance towards high environmental pCO2. In general, marine ectothermic metazoans with an extensive extracellular fluid volume may be less vulnerable to future acidification as their cells are already exposed to much higher pCO2 values (0.1 to 0.4 kPa, ca. 1000 to 3900 μatm than those of unicellular organisms and gametes, for which the ocean (0.04 kPa, ca. 400 μatm is the extracellular space. A doubling in environmental pCO2 therefore only represents a 10% change in extracellular pCO2 in some marine teleosts. High extracellular pCO2 values are to some degree related to high metabolic rates, as diffusion gradients need to be high in order to excrete an amount of CO2 that is directly proportional to the amount of O2 consumed. In active metazoans, such as teleost fish, cephalopods and many brachyuran crustaceans, exercise induced increases in metabolic rate require an efficient ion-regulatory machinery for CO2 excretion and acid-base regulation, especially when anaerobic metabolism is involved and metabolic protons leak into the extracellular space. These ion-transport systems, which are located in highly developed gill epithelia, form the basis for

  7. Antarctic marine sediments as fingerprints of pollution migration

    International Nuclear Information System (INIS)

    Waheed, S.; Ahmad, S.; Rahman, A.; Qureshi, I.H.

    2001-01-01

    Forty elements in 21 coastal marine sediment samples collected during the second Antarctic scientific expedition from 18 different sites of Brekilen area located at the coast of Antarctica were analysed by instrumental neutron activation analysis (INAA) to detect eventual pollution. Radio-assay schemes for three sets of elements after neutron irradiation and cooling were evolved to avoid matrix effects. Data have been compared with those for sediments of various stations at Antarctica and two other regions in different continents. Lower concentration of certain elements in the Antarctic sediments reflects less environmental exposition. Enrichment factors (EF) were calculated for all the elements using the earth crust as reference matrix, based on elemental values by MASON, TAYLOR and WEDEPOHL which show a normal pattern near to unity expect for Ag and Br. The data obtained could also serve as a reference point from which changes in the global environment can be studied. The quality assurance of data was performed using standard reference materials (SRMs) of a similar matrix (IAEA Marine Sediment SD-M/TM and Chinese Marine Sediment GBW 07313). (author)

  8. Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system.

    Science.gov (United States)

    Calosi, Piero; Rastrick, Samuel P S; Lombardi, Chiara; de Guzman, Heidi J; Davidson, Laura; Jahnke, Marlene; Giangrande, Adriana; Hardege, Jörg D; Schulze, Anja; Spicer, John I; Gambi, Maria-Cristina

    2013-01-01

    Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO2. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO2, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO2. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification.

  9. Depth distributions of DNA damage in Antarctic marine phyto- and bacterioplankton exposed to summertime UV radiation

    NARCIS (Netherlands)

    Buma, A.G.J.; de Boer, M.K.; Boelen, P.

    During a survey from January to March 1998, the occurrence of W-B radiation (UVBR)-induced DNA damage in Antarctic marine phytoplankton and bacterioplankton was investigated, Sampling was done in Ryder Bay, off the British base Rothera Station, 67 degreesS, 68 degreesW (British Antarctic Survey).

  10. Archive of Geosample Data and Information from the Florida State University (FSU) Antarctic Marine Geology Research Facility (AMGRF)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Antarctic Marine Geology Research Facility (AMGRF) operated by Florida State University is a partner in the Index to Marine and Lacustrine Geological Samples...

  11. A robust bioassay to assess the toxicity of metals to the Antarctic marine microalga Phaeocystis antarctica.

    Science.gov (United States)

    Gissi, Francesca; Adams, Merrin S; King, Catherine K; Jolley, Dianne F

    2015-07-01

    Despite evidence of contamination in Antarctic coastal marine environments, no water-quality guidelines have been established for the region because of a paucity of biological effects data for local Antarctic species. Currently, there is limited information on the sensitivity of Antarctic microalgae to metal contamination, which is exacerbated by the lack of standard toxicity testing protocols for local marine species. In the present study, a routine and robust toxicity test protocol was developed using the Antarctic marine microalga Phaeocystis antarctica, and its sensitivity was investigated following 10-d exposures to dissolved copper, cadmium, lead, zinc, and nickel. In comparisons of 10% inhibition of population growth rate (IC10) values, P. antarctica was most sensitive to copper (3.3 μg/L), followed by cadmium (135 μg/L), lead (260 μg/L), and zinc (450 μg/L). Although an IC10 value for nickel could not be accurately estimated, the no-observed-effect concentration value for nickel was 1070 μg/L. Exposure to copper and cadmium caused changes in internal cell granularity and increased chlorophyll a fluorescence. Lead, zinc, and nickel had no effect on any of the cellular parameters measured. The present study provides valuable metal-ecotoxicity data for an Antarctic marine microalga, with P. antarctica representing one of the most sensitive microalgal species to dissolved copper ever reported when compared with temperate and tropical species. © 2015 SETAC.

  12. Penguin eggshell membranes reflect homogeneity of mercury in the marine food web surrounding the Antarctic Peninsula

    Energy Technology Data Exchange (ETDEWEB)

    Brasso, Rebecka L., E-mail: rlb1196@uncw.edu [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States); Polito, Michael J. [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States); Lynch, Heather J. [Ecology and Evolution Department, 640 Life Sciences Bldg., Stony Brook University, Stony Brook, NY 11794 (United States); Naveen, R. [Oceanites Inc., PO Box 15259, Chevy Chase, MD 20825 (United States); Emslie, Steven D. [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States)

    2012-11-15

    Remote regions such as the Antarctic have become increasingly important for investigations into far-reaching anthropogenic impacts on the environment, most recently in regard to the global mercury cycle. Spatial patterns of mercury availability in four regions of the Antarctic Peninsula were investigated using three species of sympatrically breeding Pygoscelis penguins as biomonitors. Eggshells with intact membranes from Adelie, Gentoo, and Chinstrap penguins were collected at 24 breeding colonies in the South Orkney Islands, South Shetland Islands, eastern Antarctic Peninsula, and western Antarctic Peninsula during the 2006/2007 austral summer. In addition, we compared eggshell membrane mercury concentrations with eggshell stable isotope values ({delta}{sup 15}N and {delta}{sup 13}C) to determine if species-specific trophic or foraging habitat preferences influenced female mercury exposure prior to breeding. With few exceptions, mercury concentrations were found to be fairly homogeneous throughout the Antarctic Peninsula suggesting little spatial variation in the risk of exposure to dietary mercury in this food web. Mercury concentrations in Gentoo and Adelie penguins were similar while Chinstrap penguins tended to have higher eggshell membrane mercury concentrations than their congeners. However, inter and intra-specific differences in eggshell membrane mercury concentration were not related to eggshell {delta}{sup 15}N or {delta}{sup 13}C values, a likely result of all three species foraging at similar trophic positions. The lack of regional-scale differences in mercury availability in this marine ecosystem may be a reflection of generally uniform atmospheric deposition and upwelling of regionally homogeneous deep water rather than from geographically distinct point sources. -- Highlights: Black-Right-Pointing-Pointer We examined regional patterns of mercury availability in the Antarctic Peninsula. Black-Right-Pointing-Pointer Three species of Pygoscelis

  13. Penguin eggshell membranes reflect homogeneity of mercury in the marine food web surrounding the Antarctic Peninsula

    International Nuclear Information System (INIS)

    Brasso, Rebecka L.; Polito, Michael J.; Lynch, Heather J.; Naveen, R.; Emslie, Steven D.

    2012-01-01

    Remote regions such as the Antarctic have become increasingly important for investigations into far-reaching anthropogenic impacts on the environment, most recently in regard to the global mercury cycle. Spatial patterns of mercury availability in four regions of the Antarctic Peninsula were investigated using three species of sympatrically breeding Pygoscelis penguins as biomonitors. Eggshells with intact membranes from Adélie, Gentoo, and Chinstrap penguins were collected at 24 breeding colonies in the South Orkney Islands, South Shetland Islands, eastern Antarctic Peninsula, and western Antarctic Peninsula during the 2006/2007 austral summer. In addition, we compared eggshell membrane mercury concentrations with eggshell stable isotope values (δ 15 N and δ 13 C) to determine if species-specific trophic or foraging habitat preferences influenced female mercury exposure prior to breeding. With few exceptions, mercury concentrations were found to be fairly homogeneous throughout the Antarctic Peninsula suggesting little spatial variation in the risk of exposure to dietary mercury in this food web. Mercury concentrations in Gentoo and Adélie penguins were similar while Chinstrap penguins tended to have higher eggshell membrane mercury concentrations than their congeners. However, inter and intra-specific differences in eggshell membrane mercury concentration were not related to eggshell δ 15 N or δ 13 C values, a likely result of all three species foraging at similar trophic positions. The lack of regional-scale differences in mercury availability in this marine ecosystem may be a reflection of generally uniform atmospheric deposition and upwelling of regionally homogeneous deep water rather than from geographically distinct point sources. -- Highlights: ► We examined regional patterns of mercury availability in the Antarctic Peninsula. ► Three species of Pygoscelis penguins were used as biomonitors. ► Chinstrap penguins tended to have higher mercury

  14. Tailoring Peptidomimetics Antifreeze Protein from Exotic Antarctic Marine

    International Nuclear Information System (INIS)

    Mohd Basyaruddin Abdul Rahman; Azren Aida Asmawi; Emilia Abdulmalek

    2016-01-01

    Antifreeze proteins (AFPs) are synthesized by various cold-adapted organisms to enable them to survive in subzero environment. The unique role of AFPs recently attracted enormous interest to develop them as commercial products. In this work, we have studied the antifreeze activity of short helical protein fragments (peptides) instead of the entire antifreeze protein of Antarctic yeast Glaciozyma antarctica. Several short peptide segments were designed according to amino acid sequence of helical region of AFP-1 G.antarctica, which are assumed to be involved in its antifreeze activity. We have demonstrated that short peptide segments derived from yeast AFP possess antifreeze activity and result in modification of the ice crystals growth rates and habits. This strategy has enabled the preparation of short AFP with high antifreeze activity in large amount of quantities at a low cost further opens the chance of developing the commercial potentials of AFPs.(author)

  15. Impacts of marine instability across the East Antarctic Ice Sheet on Southern Ocean dynamics

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    S. J. Phipps

    2016-09-01

    Full Text Available Recent observations and modelling studies have demonstrated the potential for rapid and substantial retreat of large sectors of the East Antarctic Ice Sheet (EAIS. This has major implications for ocean circulation and global sea level. Here we examine the effects of increasing meltwater from the Wilkes Basin, one of the major marine-based sectors of the EAIS, on Southern Ocean dynamics. Climate model simulations reveal that the meltwater flux rapidly stratifies surface waters, leading to a dramatic decrease in the rate of Antarctic Bottom Water (AABW formation. The surface ocean cools but, critically, the Southern Ocean warms by more than 1 °C at depth. This warming is accompanied by a Southern Ocean-wide “domino effect”, whereby the warming signal propagates westward with depth. Our results suggest that melting of one sector of the EAIS could result in accelerated warming across other sectors, including the Weddell Sea sector of the West Antarctic Ice Sheet. Thus, localised melting of the EAIS could potentially destabilise the wider Antarctic Ice Sheet.

  16. Sub-Antarctic marine aerosol: dominant contributions from biogenic sources

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    J. Schmale

    2013-09-01

    Full Text Available Biogenic influences on the composition and characteristics of aerosol were investigated on Bird Island (54°00' S, 38°03' W in the South Atlantic during November and December 2010. This remote marine environment is characterised by large seabird and seal colonies. The chemical composition of the submicron particles, measured by an aerosol mass spectrometer (AMS, was 21% non-sea-salt sulfate, 2% nitrate, 8% ammonium, 22% organics and 47% sea salt including sea salt sulfate. A new method to isolate the sea spray signature from the high-resolution AMS data was applied. Generally, the aerosol was found to be less acidic than in other marine environments due to the high availability of ammonia, from local fauna emissions. By positive matrix factorisation five different organic aerosol (OA profiles could be isolated: an amino acid/amine factor (AA-OA, 18% of OA mass, a methanesulfonic acid OA factor (MSA-OA, 25%, a marine oxygenated OA factor (M-OOA, 41%, a sea spray OA fraction (SS-OA, 7% and locally produced hydrocarbon-like OA (HOA, 9%. The AA-OA was dominant during the first two weeks of November and found to be related with the hatching of penguins in a nearby colony. This factor, rich in nitrogen (N : C ratio = 0.13, has implications for the biogeochemical cycling of nitrogen in the area as particulate matter is often transported over longer distances than gaseous N-rich compounds. The MSA-OA was mainly transported from more southerly latitudes where phytoplankton bloomed. The bloom was identified as one of three sources for particulate sulfate on Bird Island, next to sea salt sulfate and sulfate transported from South America. M-OOA was the dominant organic factor and found to be similar to marine OA observed at Mace Head, Ireland. An additional OA factor highly correlated with sea spray aerosol was identified (SS-OA. However, based on the available data the type of mixture, internal or external, could not be determined. Potassium was not

  17. Climate change and the marine ecosystem of the western Antarctic Peninsula

    Science.gov (United States)

    Clarke, Andrew; Murphy, Eugene J; Meredith, Michael P; King, John C; Peck, Lloyd S; Barnes, David K.A; Smith, Raymond C

    2006-01-01

    The Antarctic Peninsula is experiencing one of the fastest rates of regional climate change on Earth, resulting in the collapse of ice shelves, the retreat of glaciers and the exposure of new terrestrial habitat. In the nearby oceanic system, winter sea ice in the Bellingshausen and Amundsen seas has decreased in extent by 10% per decade, and shortened in seasonal duration. Surface waters have warmed by more than 1 K since the 1950s, and the Circumpolar Deep Water (CDW) of the Antarctic Circumpolar Current has also warmed. Of the changes observed in the marine ecosystem of the western Antarctic Peninsula (WAP) region to date, alterations in winter sea ice dynamics are the most likely to have had a direct impact on the marine fauna, principally through shifts in the extent and timing of habitat for ice-associated biota. Warming of seawater at depths below ca 100 m has yet to reach the levels that are biologically significant. Continued warming, or a change in the frequency of the flooding of CDW onto the WAP continental shelf may, however, induce sublethal effects that influence ecological interactions and hence food-web operation. The best evidence for recent changes in the ecosystem may come from organisms which record aspects of their population dynamics in their skeleton (such as molluscs or brachiopods) or where ecological interactions are preserved (such as in encrusting biota of hard substrata). In addition, a southwards shift of marine isotherms may induce a parallel migration of some taxa similar to that observed on land. The complexity of the Southern Ocean food web and the nonlinear nature of many interactions mean that predictions based on short-term studies of a small number of species are likely to be misleading. PMID:17405211

  18. Climate change and the marine ecosystem of the western Antarctic Peninsula.

    Science.gov (United States)

    Clarke, Andrew; Murphy, Eugene J; Meredith, Michael P; King, John C; Peck, Lloyd S; Barnes, David K A; Smith, Raymond C

    2007-01-29

    The Antarctic Peninsula is experiencing one of the fastest rates of regional climate change on Earth, resulting in the collapse of ice shelves, the retreat of glaciers and the exposure of new terrestrial habitat. In the nearby oceanic system, winter sea ice in the Bellingshausen and Amundsen seas has decreased in extent by 10% per decade, and shortened in seasonal duration. Surface waters have warmed by more than 1 K since the 1950s, and the Circumpolar Deep Water (CDW) of the Antarctic Circumpolar Current has also warmed. Of the changes observed in the marine ecosystem of the western Antarctic Peninsula (WAP) region to date, alterations in winter sea ice dynamics are the most likely to have had a direct impact on the marine fauna, principally through shifts in the extent and timing of habitat for ice-associated biota. Warming of seawater at depths below ca 100 m has yet to reach the levels that are biologically significant. Continued warming, or a change in the frequency of the flooding of CDW onto the WAP continental shelf may, however, induce sublethal effects that influence ecological interactions and hence food-web operation. The best evidence for recent changes in the ecosystem may come from organisms which record aspects of their population dynamics in their skeleton (such as molluscs or brachiopods) or where ecological interactions are preserved (such as in encrusting biota of hard substrata). In addition, a southwards shift of marine isotherms may induce a parallel migration of some taxa similar to that observed on land. The complexity of the Southern Ocean food web and the nonlinear nature of many interactions mean that predictions based on short-term studies of a small number of species are likely to be misleading.

  19. The Osservatorio Geofisico Sperimentale marine magnetic surveys in the Antarctic Seas

    Directory of Open Access Journals (Sweden)

    C. Zanolla

    1999-06-01

    Full Text Available About 40 000 km of marine magnetic and gradiometric data have been collected during eight geophysical surveys conducted since the Austral summer 1987/1988 in the circum-antarctic seas, by the research vessel OGS-Explora. For the most surveyed areas (Ross Sea, Southwestern Pacific Ocean, and Southern Scotia Sea, the analysis of the acquired data have contributed to clarify important aspects of their geological structure and tectonic evolution. The main scientific results, obtained combining other available geophysical data (multichannel seismic profiles and satellite-derived data, will be briefly illustrated.

  20. Rhodotorula portillonensis sp. nov., a basidiomycetous yeast isolated from Antarctic shallow-water marine sediment.

    Science.gov (United States)

    Laich, Federico; Vaca, Inmaculada; Chávez, Renato

    2013-10-01

    During the characterization of the mycobiota associated with shallow-water marine environments from Antarctic sea, a novel pink yeast species was isolated. Sequence analysis of the D1/D2 domain of the LSU rDNA gene and 5.8S-ITS regions revealed that the isolated yeast was closely related to Rhodotorula pallida CBS 320(T) and Rhodotorula benthica CBS 9124(T). On the basis of morphological, biochemical and physiological characterization and phylogenetic analyses, a novel basidiomycetous yeast species, Rhodotorula portillonensis sp. nov., is proposed. The type strain is Pi2(T) ( = CBS 12733(T)  = CECT 13081(T)) which was isolated from shallow-water marine sediment in Fildes Bay, King George Island, Antarctica.

  1. Time Matters: Increasing the Efficiency of Antarctic Marine Geology and Paleoceanography Expeditions by Providing Improved Sediment Chronology

    Science.gov (United States)

    Rosenheim, B. E.; Domack, E. W.; Shevenell, A.; Subt, C.

    2015-12-01

    To maximize the areal extent of Antarctic sedimentary records of past deglaciation, it is necessary to ensure more sediment cores can be adequately dated. Antarctic margin sediment is challenging to date due to the lack of preserved calcium carbonate, but the records contained in these sediments readily recount the history of deglaciation. Recent and continued development of new chronological methods for Antarctic margin sediments have allowed better use of the efforts of marine geological coring expeditions to the region. The development of Ramped PyrOx radiocarbon dating has allowed us to 1. improve dates in deglacial sediments where no carbonate is preserved, 2. date glacial sediments lying below the tills marking the last glaciation, and 3. compile core chronologies into a regional framework of ice shelf collapse that has eluded many marine geology campaigns over the last few decades. These advances in a fundamental aspect of geological sciences will put the U.S. and international community on a better foothold to interpret the past as it relates to our warming future. We will present these advances in chronology as well as the science that is enabled by them, while arguing that the future of Antarctic marine science also depends on investments in shore-based technologies that come at a relatively low cost.

  2. Metal and antibiotic-resistance in psychrotrophic bacteria from Antarctic marine waters

    Digital Repository Service at National Institute of Oceanography (India)

    De; Nair, S.; LokaBharathi, P.A.; Chandramohan, D.

    In the wake of the findings that Antarctic krills concentrate heavy metals at ppm level, (Yamamoto et al., 1987), the Antarctic waters from the Indian side were examined for the incidence of metal and antibiotic-resistant bacteria during...

  3. Mollusc shells as archival indicators of metal contamination in the Australian antarctic marine environment

    International Nuclear Information System (INIS)

    Simpson, R.D.

    2000-01-01

    Full text: Although considered by many to be a pristine environment past activities in Antarctica have caused localised contamination. In particular, the practice of disposing of station waste in open tips adjacent to the seashore has caused heavy metals to migrate to the marine environment. Times have changed and these practices are no longer permitted. Under international agreements, such as the Protocol on Environmental Protection to the Antarctic Treaty System, operators are now required to clean-up these sites so long as the act of clean-up does not cause greater environmental harm than leaving them where they are. The Australian Antarctic Division has embarked on a program to develop techniques for clean-up and remediation of disused waste disposal sites and is also developing techniques for monitoring the environment to ensure that clean-up does not cause greater environmental harm. The Antarctic clam, Laternula elliptica, is common in near shore sediments around the entire coast of Antarctica. It is a filter feeder that extracts suspended sediments from the water column and has been suggested as a candidate for mussel watch-type monitoring in Antarctica. Contaminants in waste disposal tips in Antarctica are likely to be mobilised in pulses caused by the seasonal flush of melting snow as it passes through the contaminated material. As a filter feeder Laternula will be exposed to the highest concentrations of contaminants while they remain in suspension. If contaminants are sequestered into the shells of the bivalve and if their levels in the shell can be analysed in relation to the annual growth rings then they may prove to be a useful archive of past environmental contamination. Specimens of Laternula were exposed to known concentrations of copper and cadmium under aquarium conditions in Antarctica to understand accumulation and depuration rates in the soft tissues. This information is used to assist interpretation of concentrations in animals collected

  4. Size distribution and ionic composition of marine summer aerosol at the continental Antarctic site Kohnen

    Science.gov (United States)

    Weller, Rolf; Legrand, Michel; Preunkert, Susanne

    2018-02-01

    We measured aerosol size distributions and conducted bulk and size-segregated aerosol sampling during two summer campaigns in January 2015 and January 2016 at the continental Antarctic station Kohnen (Dronning Maud Land). Physical and chemical aerosol properties differ conspicuously during the episodic impact of a distinctive low-pressure system in 2015 (LPS15) compared to the prevailing clear sky conditions. The approximately 3-day LPS15 located in the eastern Weddell Sea was associated with the following: marine boundary layer air mass intrusion; enhanced condensation particle concentrations (1400 ± 700 cm-3 compared to 250 ± 120 cm-3 under clear sky conditions; mean ± SD); the occurrence of a new particle formation event exhibiting a continuous growth of particle diameters (Dp) from 12 to 43 nm over 44 h (growth rate 0.6 nm h-1); peaking methane sulfonate (MS-), non-sea-salt sulfate (nss-SO42-), and Na+ concentrations (190 ng m-3 MS-, 137 ng m-3 nss-SO42-, and 53 ng m-3 Na+ compared to 24 ± 15, 107 ± 20, and 4.1 ± 2.2 ng m-3, respectively, during clear sky conditions); and finally an increased MS- / nss-SO42- mass ratio βMS of 0.4 up to 2.3 (0.21 ± 0.1 under clear sky conditions) comparable to typical values found at coastal Antarctic sites. Throughout the observation period a larger part of MS- could be found in super-micron aerosol compared to nss-SO42-, i.e., (10 ± 2) % by mass compared to (3.2 ± 2) %, respectively. On the whole, under clear sky conditions aged aerosol characterized by usually mono-modal size distributions around Dp = 60 nm was observed. Although our observations indicate that the sporadic impacts of coastal cyclones were associated with enhanced marine aerosol entry, aerosol deposition on-site during austral summer should be largely dominated by typical steady clear sky conditions.

  5. Microplastics in the Antarctic marine system: An emerging area of research.

    Science.gov (United States)

    Waller, Catherine L; Griffiths, Huw J; Waluda, Claire M; Thorpe, Sally E; Loaiza, Iván; Moreno, Bernabé; Pacherres, Cesar O; Hughes, Kevin A

    2017-11-15

    It was thought that the Southern Ocean was relatively free of microplastic contamination; however, recent studies and citizen science projects in the Southern Ocean have reported microplastics in deep-sea sediments and surface waters. Here we reviewed available information on microplastics (including macroplastics as a source of microplastics) in the Southern Ocean. We estimated primary microplastic concentrations from personal care products and laundry, and identified potential sources and routes of transmission into the region. Estimates showed the levels of microplastic pollution released into the region from ships and scientific research stations were likely to be negligible at the scale of the Southern Ocean, but may be significant on a local scale. This was demonstrated by the detection of the first microplastics in shallow benthic sediments close to a number of research stations on King George Island. Furthermore, our predictions of primary microplastic concentrations from local sources were five orders of magnitude lower than levels reported in published sampling surveys (assuming an even dispersal at the ocean surface). Sea surface transfer from lower latitudes may contribute, at an as yet unknown level, to Southern Ocean plastic concentrations. Acknowledging the lack of data describing microplastic origins, concentrations, distribution and impacts in the Southern Ocean, we highlight the urgent need for research, and call for routine, standardised monitoring in the Antarctic marine system. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Can acclimation of thermal tolerance, in adults and across generations, act as a buffer against climate change in tropical marine ectotherms?

    Science.gov (United States)

    Morley, S A; Nguyen, K D; Peck, L S; Lai, C-H; Tan, K S

    2017-08-01

    Thermal acclimation capacity was investigated in adults of three tropical marine invertebrates, the subtidal barnacle Striatobalanus amaryllis, the intertidal gastropod Volegalea cochlidium and the intertidal barnacle Amphibalanus amphitrite. To test the relative importance of transgenerational acclimation, the developmental acclimation capacity of A. amphitrite was investigated in F 1 and F 2 generations reared at a subset of the same incubation temperatures. The increase in CT max (measured through loss of key behavioural metrics) of F 0 adults across the incubation temperature range 25.4-33.4°C was low: 0.00°C (V. cochlidium), 0.05°C (S. amaryllis) and 0.06°C (A. amphitrite) per 1°C increase in incubation temperature (the acclimation response ratio; ARR). Although the effect of generation was not significant, across the incubation temperature range of 29.4-33.4°C, the increase in CT max in the F 1 (0.30°C) and F 2 (0.15°C) generations of A. amphitrite was greater than in the F 0 (0.10°C). These correspond to ARR's of 0.03°C (F 0 ), 0.08°C (F 1 ) and 0.04°C (F 2 ), respectively. The variability in CT max between individuals in each treatment was maintained across generations, despite the high mortality of progeny. Further research is required to investigate the potential for transgenerational acclimation to provide an extra buffer for tropical marine species facing climate warming. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Heat loss in air of an Antarctic marine mammal, the Weddell seal.

    Science.gov (United States)

    Mellish, Jo-Ann; Hindle, Allyson; Skinner, John; Horning, Markus

    2015-01-01

    The conflicting needs of homeostasis in air versus water complicate our understanding of thermoregulation in marine mammals. Large-scale modeling efforts directed at predicting the energetic impact of changing sea ice conditions on polar ecosystems require a better understanding of thermoregulation in air of free-ranging animals. We utilized infrared imaging as an indirect approach to determine surface temperatures of dry, hauled-out Weddell seals (Leptonychotes weddellii, n = 35) of varying age and body condition during the Antarctic summer. The study groups provided a fivefold range in body mass and a threefold range in blubber depth. Surface temperature (T s) did not vary by body region (head, shoulder, axilla, torso, hip, flippers). Average seal T s (mean 13.9 ± 11.2 °C) was best described through a combination of the physical traits of body mass and environmental variables of ambient temperature T air, and wind speed. Additional factors of ice temperature (T ice), relative humidity and cloud cover did not improve the model. Heat transfer model estimates suggested that radiation contributed 56.6 ± 7.7 % of total heat loss. Convection and conduction accounted for the remaining 15.7 ± 12.3 and 27.7 ± 9.3 %, respectively. Heat loss by radiation was primarily influenced by body mass and wind speed, whereas convective heat loss was influenced primarily by blubber depth and wind speed. Conductive heat loss was modeled largely as a function of physical traits of mass and blubber depth rather than any environmental covariates, and therefore was substantially higher in animals in leaner condition.

  8. Assessing fuel spill risks in polar waters: Temporal dynamics and behaviour of hydrocarbons from Antarctic diesel, marine gas oil and residual fuel oil.

    Science.gov (United States)

    Brown, Kathryn E; King, Catherine K; Kotzakoulakis, Konstantinos; George, Simon C; Harrison, Peter L

    2016-09-15

    As part of risk assessment of fuel oil spills in Antarctic and subantarctic waters, this study describes partitioning of hydrocarbons from three fuels (Special Antarctic Blend diesel, SAB; marine gas oil, MGO; and intermediate grade fuel oil, IFO 180) into seawater at 0 and 5°C and subsequent depletion over 7days. Initial total hydrocarbon content (THC) of water accommodated fraction (WAF) in seawater was highest for SAB. Rates of THC loss and proportions in equivalent carbon number fractions differed between fuels and over time. THC was most persistent in IFO 180 WAFs and most rapidly depleted in MGO WAF, with depletion for SAB WAF strongly affected by temperature. Concentration and composition remained proportionate in dilution series over time. This study significantly enhances our understanding of fuel behaviour in Antarctic and subantarctic waters, enabling improved predictions for estimates of sensitivities of marine organisms to toxic contaminants from fuels in the region. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Marine foraging and annual fish consumption of a south polar Skua population in the maritime Antarctic

    NARCIS (Netherlands)

    Hahn, S.M.; Ritz, M.S.; Reinhardt, K.

    2008-01-01

    Pelagic fish are an important component of Antarctic food webs but few quantitative data exist on energy transfer from fish to seabirds for the Seasonal Pack-ice Zone. We studied a local population of south polar, skuas Catharacta maccormicki during a whole breeding cycle and estimated its entire

  10. Alginate overproduction and biofilm formation by psychrotolerant Pseudomonas mandelii depend on temperature in Antarctic marine sediments

    Directory of Open Access Journals (Sweden)

    Felipe Vásquez-Ponce

    2017-07-01

    Conclusion: Because biofilm formation is an efficient bacterial strategy to overcome stressful conditions, alginate overproduction might represent the best solution for the successful adaptation of P. mandelii to the extreme temperatures of the Antarctic. Through additional research, it is possible that this novel P. mandelii strain could become an additional source for biotechnological alginate production.

  11. Combined ice core and climate-model evidence for the collapse of the West Antarctic Ice Sheet during Marine Isotope Stage 5e.

    Science.gov (United States)

    Steig, Eric J.; Huybers, Kathleen; Singh, Hansi A.; Steiger, Nathan J.; Frierson, Dargan M. W.; Popp, Trevor; White, James W. C.

    2015-04-01

    It has been speculated that collapse of the West Antarctic Ice Sheet explains the very high eustatic sea level rise during the last interglacial period, marine isotope stage (MIS) 5e, but the evidence remains equivocal. Changes in atmospheric circulation resulting from a collapse of the West Antarctic Ice Sheet (WAIS) would have significant regional impacts that should be detectable in ice core records. We conducted simulations using general circulation models (GCMs) at varying levels of complexity: a gray-radiation aquaplanet moist GCM (GRaM), the slab ocean version of GFDL-AM2 (also as an aquaplanet), and the fully-coupled version of NCAR's CESM with realistic topography. In all the experiments, decreased elevation from the removal of the WAIS leads to greater cyclonic circulation over the West Antarctic region. This creates increased advection of relatively warm marine air from the Amundsen-Bellingshausen Seas towards the South Pole, and increased cold-air advection from the East Antarctic plateau towards the Ross Sea and coastal Marie Byrd Land. The result is anomalous warming in some areas of the East Antarctic interior, and significant cooling in Marie Byrd Land. Comparison of ice core records shows good agreement with the model predictions. In particular, isotope-paleotemperature records from ice cores in East Antarctica warmed more between the previous glacial period (MIS 6) and MIS 5e than coastal Marie Byrd Land. These results add substantial support to other evidence for WAIS collapse during the last interglacial period.

  12. Distinct genetic differentiation and species diversification within two marine nematodes with different habitat preference in Antarctic sediments.

    Science.gov (United States)

    Hauquier, Freija; Leliaert, Frederik; Rigaux, Annelien; Derycke, Sofie; Vanreusel, Ann

    2017-05-30

    Dispersal ability, population genetic structure and species divergence in marine nematodes are still poorly understood, especially in remote areas such as the Southern Ocean. We investigated genetic differentiation of species and populations of the free-living endobenthic nematode genera Sabatieria and Desmodora using nuclear 18S rDNA, internal transcribed spacer (ITS) rDNA, and mitochondrial cytochrome oxidase I (COI) gene sequences. Specimens were collected at continental shelf depths (200-500 m) near the Antarctic Peninsula, Scotia Arc and eastern side of the Weddell Sea. The two nematode genera co-occurred at all sampled locations, but with different vertical distribution in the sediment. A combination of phylogenetic (GMYC, Bayesian Inference, Maximum Likelihood) and population genetic (AMOVA) analyses were used for species delimitation and assessment of gene flow between sampling locations. Sequence analyses resulted in the delimitation of four divergent species lineages in Sabatieria, two of which could not be discriminated morphologically and most likely constitute cryptic species. Two species were recognised in Desmodora, one of which showed large intraspecific morphological variation. Both genera comprised species that were restricted to one side of the Weddell Sea and species that were widely spread across it. Population genetic structuring was highly significant and more pronounced in the deeper sediment-dwelling Sabatieria species, which are generally less prone to resuspension and passive dispersal in the water column than surface Desmodora species. Our results indicate that gene flow is restricted at large geographic distance in the Southern Ocean, which casts doubt on the efficiency of the Weddell gyre and Antarctic Circumpolar Current in facilitating circum-Antarctic nematode species distributions. We also show that genetic structuring and cryptic speciation can be very different in nematode species isolated from the same geographic area, but with

  13. Seawater and Detrital Marine Pb Isotopes as Monitors of Antarctic Weathering Following Ice Sheet Development

    Science.gov (United States)

    Fenn, C.; Martin, E. E.; Basak, C.

    2011-12-01

    Comparisons of seawater and detrital Pb isotopes from sites proximal to Antarctica at the Eocene/Oligocene transition (EOT) are being used to understand variations in continental weathering associated with the development of the East Antarctic Ice Sheet (EAIS). Previous work has shown that seawater and detrital archives yield similar isotopic values during Eocene warmth, which is interpreted to record congruent chemical weathering of the continent. In contrast, distinct isotopic values for the two phases at the EOT represents increased incongruent mechanical weathering during growth of the ice sheet. For this study we expanded beyond the initial glaciation at the EOT to determine whether less dramatic changes in ice volume and climate also produce variations in weathering and intensity that are recorded by seawater and detrital Pb isotopes. We collected Nd and Pb isotope data from extractions of Fe-Mn oxide coatings of bulk decarbonated marine sediments, which preserve seawater isotopic values, and from complete dissolutions of the remaining silicate fraction for Ocean Drilling Program Site 748 on Kerguelen Plateau (1300 m modern water depth). The data spans an interval of deglaciation from ~23.5-27 Ma documented by δ18O that has been equated to a ~30% decrease in ice volume on Antarctica (Pekar and Christie-Blick, 2008, Palaeogeogr., Palaeoclim., Palaeoecol.). Initial results from Site 748 include the first ɛNd values for intermediate waters in the Oligocene Southern Ocean and reveal a value of ~-8 over the entire 3.5 my interval, which is consistent with values reported for deep Indian Ocean sites at this time and similar to deeper Southern Ocean sites. Corresponding detrital ɛNd values are less radiogenic and decrease from -9 to -13 during the study interval. Detrital 206Pb/204Pb values also decrease during the warming interval, while seawater 206Pb/204Pb values increase. The decrease in detrital values indicates the composition of source materials entering

  14. Changes in viability of two Antarctic marine bacteria exposed to solar radiation in the water column: influence of vertical mixing

    International Nuclear Information System (INIS)

    Hernandez, E.A.

    2007-01-01

    The effect of UV radiation on two Antarctic marine bacterial strains (UVps and UVvi) was studied in the water column of Potter Cove (South Shetland, Antarctica). Quartz flasks were filled with the bacterial suspensions and exposed to solar radiation at 0 m, 1 m and 3 m depth. Assays using flasks exposed to direct solar radiation and others using flasks covered with/by interferential filters which discriminate between UVA and UVB, were performed. In other assays, a vertical mixing of 4 m/h was simulated. Both strains showed a significant decrease in viability (expressed as colony - forming units) when exposed to a surface UVB dose of 8.4 kJ m -2 . Studies with interferential filters showed a significant decrease at 0 and 1 m depth under both UV treatments. The UVps strain appeared to be more sensitive to UVB than to UVA. Damage produced by UVB was attenuated by the vertical mixing when the surface UVB dose was 4.8 kJ m -2 . This effect was not observed when surface UVB dose was 7.7 kJ m -2 . These results show that the negative effect caused by UVB radiation on the bacterio plankton would be significant only in the first meter of water column of the Antarctic coastal waters with high levels of suspended particulate material. (author) [es

  15. Transport of soil particles to the ocean and their concentration in the marine atmosphere - A case study of marine aerosols collected during the cruises of the Antarctic observation ship Shirase

    International Nuclear Information System (INIS)

    Tanaka, Shigeru; Okamori, Katsutaka; Hashimoto, Yoshikazu

    1991-01-01

    The marine aerosol samples over the West Pacific Ocean, the Indian Ocean, and the Antarctic Ocean, collected during the cruises of the Antarctic observation ship Shirase, were analyzed by X-ray fluorescence. As the results, the average concentration of soil derived elements were 11.9 ng/m 3 for Al, 50.6 ng/m 3 for Si, 12.5 ng/m 3 for Fe, over the West Pacific Ocean. These values were so low as 1/100 of their concentrations in the land. Furthermore, these concentrations over the Indian Ocean and the Antarctic Ocean were extremely low, 6.5 ng/m 3 for Al, 13.4 ng/m 3 for Si, 3.5 ng/m 3 for Fe with average. It is considered that these values are the background concentration of soil derived elements in the marine atmosphere

  16. Marine and terrestrial factors affecting Adélie penguin Pygoscelis adeliae chick growth and recruitment off the western Antarctic Peninsula

    Science.gov (United States)

    Chapman, Erik W.; Hofmann, Eileen E.; Patterson, Donna L.; Ribic, Christine A.; Fraser, William R.

    2011-01-01

    An individual-based bioenergetics model that simulates the growth of an Adélie penguin Pygoscelis adeliaechick from hatching to fledging was used to assess marine and terrestrial factors that affect chick growth and fledging mass off the western Antarctic Peninsula. Simulations considered the effects on Adélie penguin fledging mass of (1) modification of chick diet through the addition of Antarctic silverfish Pleuragramma antarcticum to an all-Antarctic krillEuphausia superba diet, (2) reduction of provisioning rate which may occur as a result of an environmental stress such as reduced prey availability, and (3) increased thermoregulatory costs due to wetting of chicks which may result from increased precipitation or snow-melt in colonies. Addition of 17% Antarctic silverfish of Age-Class 3 yr (AC3) to a penguin chick diet composed of Antarctic krill increased chick fledging mass by 5%. Environmental stress that results in >4% reduction in provisioning rate or wetting of just 10% of the chick’s surface area decreased fledging mass enough to reduce the chick’s probability of successful recruitment. The negative effects of reduced provisioning and wetting on chick growth can be compensated for by inclusion of Antarctic silverfish of AC3 and older in the chick diet. Results provide insight into climate-driven processes that influence chick growth and highlight a need for field research designed to investigate factors that determine the availability of AC3 and older Antarctic silverfish to foraging Adélie penguins and the influence of snowfall on chick wetting, thermoregulation and adult provisioning rate.

  17. Organic compounds and suspended matter in the marine ice of the Eastern Antarctic

    International Nuclear Information System (INIS)

    Nemirovskaya, I.A.; Novigatsky, A.N.

    2005-01-01

    Data on the composition of organic compounds in Antarctic sea ice are virtually non-existent, as most works concentrate on the structure, physical composition and biological properties of the ice. Data is needed for the study of the global carbon cycle and the estimation of background values and anthropogenic compounds. Specific features of the hydrometeorological regime near Antarctica affect the structure of the ice cover and its properties. The transportation of large volumes of snow to the ocean results in the formation of a snow sludge layer which gradually accumulates on the sea surface and freezes into young slush ice. The irregular distribution of snow at the ice surface and seawater infiltration results in the formation of ice with a specific crystalline structure and physiochemical properties. This paper discussed the dissolved and suspended lipids and hydrocarbons, as well as suspended matter (SM) concentrations in snow, sea ice and sub-ice water in coastal zones of the East Antarctic. The data was obtained during the Russian Antarctic Expedition in 2003. Variations in the concentration and distribution of the various substances suggest that they are related to ice forming conditions and to the processes that occur when ice forms, as well as in the interaction of the substances with ice, snow and sub-ice water. The SM and organic compounds are accumulated in layers characterized by intense autochthonous processes. It was noted that the zones stay biogeochemically active even under low temperature conditions. The highest concentrations of organic compounds, along with the biggest variations in their proportions have been discovered in the areas surrounded by penguin colonies near Buromsky Island and Haswell Island's Lake. The presence of significant quantities of PAHs in both pack and seasonal ice of high latitudes indicates that their formation is relatively rapid even at low temperatures. Many biochemical processes are intense under the influence of ice

  18. Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO2 tolerance in phytoplankton productivity

    Science.gov (United States)

    Deppeler, Stacy; Petrou, Katherina; Schulz, Kai G.; Westwood, Karen; Pearce, Imojen; McKinlay, John; Davidson, Andrew

    2018-01-01

    High-latitude oceans are anticipated to be some of the first regions affected by ocean acidification. Despite this, the effect of ocean acidification on natural communities of Antarctic marine microbes is still not well understood. In this study we exposed an early spring, coastal marine microbial community in Prydz Bay to CO2 levels ranging from ambient (343 µatm) to 1641 µatm in six 650 L minicosms. Productivity assays were performed to identify whether a CO2 threshold existed that led to a change in primary productivity, bacterial productivity, and the accumulation of chlorophyll a (Chl a) and particulate organic matter (POM) in the minicosms. In addition, photophysiological measurements were performed to identify possible mechanisms driving changes in the phytoplankton community. A critical threshold for tolerance to ocean acidification was identified in the phytoplankton community between 953 and 1140 µatm. CO2 levels ≥ 1140 µatm negatively affected photosynthetic performance and Chl a-normalised primary productivity (csGPP14C), causing significant reductions in gross primary production (GPP14C), Chl a accumulation, nutrient uptake, and POM production. However, there was no effect of CO2 on C : N ratios. Over time, the phytoplankton community acclimated to high CO2 conditions, showing a down-regulation of carbon concentrating mechanisms (CCMs) and likely adjusting other intracellular processes. Bacterial abundance initially increased in CO2 treatments ≥ 953 µatm (days 3-5), yet gross bacterial production (GBP14C) remained unchanged and cell-specific bacterial productivity (csBP14C) was reduced. Towards the end of the experiment, GBP14C and csBP14C markedly increased across all treatments regardless of CO2 availability. This coincided with increased organic matter availability (POC and PON) combined with improved efficiency of carbon uptake. Changes in phytoplankton community production could have negative effects on the Antarctic food web and the

  19. Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO2 tolerance in phytoplankton productivity

    Directory of Open Access Journals (Sweden)

    S. Deppeler

    2018-01-01

    Full Text Available High-latitude oceans are anticipated to be some of the first regions affected by ocean acidification. Despite this, the effect of ocean acidification on natural communities of Antarctic marine microbes is still not well understood. In this study we exposed an early spring, coastal marine microbial community in Prydz Bay to CO2 levels ranging from ambient (343 µatm to 1641 µatm in six 650 L minicosms. Productivity assays were performed to identify whether a CO2 threshold existed that led to a change in primary productivity, bacterial productivity, and the accumulation of chlorophyll a (Chl a and particulate organic matter (POM in the minicosms. In addition, photophysiological measurements were performed to identify possible mechanisms driving changes in the phytoplankton community. A critical threshold for tolerance to ocean acidification was identified in the phytoplankton community between 953 and 1140 µatm. CO2 levels  ≥ 1140 µatm negatively affected photosynthetic performance and Chl a-normalised primary productivity (csGPP14C, causing significant reductions in gross primary production (GPP14C, Chl a accumulation, nutrient uptake, and POM production. However, there was no effect of CO2 on C : N ratios. Over time, the phytoplankton community acclimated to high CO2 conditions, showing a down-regulation of carbon concentrating mechanisms (CCMs and likely adjusting other intracellular processes. Bacterial abundance initially increased in CO2 treatments  ≥ 953 µatm (days 3–5, yet gross bacterial production (GBP14C remained unchanged and cell-specific bacterial productivity (csBP14C was reduced. Towards the end of the experiment, GBP14C and csBP14C markedly increased across all treatments regardless of CO2 availability. This coincided with increased organic matter availability (POC and PON combined with improved efficiency of carbon uptake. Changes in phytoplankton community production could have negative

  20. Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral Summer

    Directory of Open Access Journals (Sweden)

    Rebecca J. Gast

    2018-02-01

    Full Text Available Identifying putative mixotrophic protist species in the environment is important for understanding their behavior, with the recovery of these species in culture essential for determining the triggers of feeding, grazing rates, and overall impact on bacterial standing stocks. In this project, mixotroph abundances determined using tracer ingestion in water and sea ice samples collected in the Ross Sea, Antarctica during the summer of 2011 were compared with data from the spring (Ross Sea and fall (Arctic to examine the impacts of bacterivory/mixotrophy. Mixotrophic nanoplankton (MNAN were usually less abundant than heterotrophs, but consumed more of the bacterial standing stock per day due to relatively higher ingestion rates (1–7 bacteria mixotroph−1 h−1 vs. 0.1–4 bacteria heterotroph−1 h−1. Yet, even with these high rates observed in the Antarctic summer, mixotrophs appeared to have a smaller contribution to bacterivory than in the Antarctic spring. Additionally, putative mixotroph taxa were identified through incubation experiments accomplished with bromodeoxyuridine-labeled bacteria as food, immunoprecipitation (IP of labeled DNA, and amplification and high throughput sequencing of the eukaryotic ribosomal V9 region. Putative mixotroph OTUs were identified in the IP samples by taxonomic similarity to known phototroph taxa. OTUs that had increased abundance in IP samples compared to the non-IP samples from both surface and chlorophyll maximum (CM depths were considered to represent active mixotrophy and include ones taxonomically similar to Dictyocha, Gymnodinium, Pentapharsodinium, and Symbiodinium. These OTUs represent target taxa for isolation and laboratory experiments on triggers for mixotrophy, to be combined with qPCR to estimate their abundance, seasonal distribution and potential impact.

  1. Antarctic krill 454 pyrosequencing reveals chaperone and stress transcriptome.

    Directory of Open Access Journals (Sweden)

    Melody S Clark

    marine ectotherms' capacities to cope with environmental change.

  2. Production, purification, and characterization of an extracellular acid protease from the marine Antarctic yeast Rhodotorula mucilaginosa L7.

    Science.gov (United States)

    Lario, Luciana Daniela; Chaud, Luciana; Almeida, María das Graças; Converti, Attilio; Durães Sette, Lara; Pessoa, Adalberto

    2015-11-01

    The production, purification, and characterization of an extracellular protease released by Rhodotorula mucilaginosa L7 were evaluated in this study. This strain was isolated from an Antarctic marine alga and previously selected among others based on the capacity to produce the highest extracellular proteolytic activity in preliminary tests. R. mucilaginosa L7 was grown in Saboraud-dextrose medium at 25 °C, and the cell growth, pH of the medium, extracellular protease production and the glucose and protein consumption were determined as a function of time. The protease was then purified, and the effects of pH, temperature, and salt concentration on the catalytic activity and enzyme stability were determined. Enzyme production started at the beginning of the exponential phase of growth and reached a maximum after 48 h, which was accompanied by a decrease in the pH as well as reductions of the protein and glucose concentrations in the medium. The purified protease presented optimal catalytic activity at pH 5.0 and 50 °C. Finally, the enzyme was stable in the presence of high concentrations of NaCl. These characteristics are of interest for future studies and may lead to potential biotechnological applications that require enzyme activity and stability under acidic conditions and/or high salt concentrations. Copyright © 2015 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  3. Effects of ultraviolet light on photosynthesis and pigments of Antarctic marine phytoplankton

    International Nuclear Information System (INIS)

    Stephens, F.C.

    1989-01-01

    This field study was conducted at Palmer Station, Anvers Island, Antarctica, during November-December, 1987. The main objectives were to quantify the effects on photosynthetic rates and pigmentation of short-term and long-term exposures of Antarctic phytoplankton to different levels of UV radiation. Phytoplankton and ice algae were exposed to four levels of UV radiation in outdoor incubation chambers: near ambient UV; UV enhanced by approximately 5% over ambient levels; reduced UV-B; and essentially no UV. Results of 4-hour studies showed that rates of phytoplankton photosynthesis were generally inversely related to UV exposure. Higher photosynthetic rates were maintained over a greater range of irradiance levels when UV was removed in photosynthesis-irradiance studies. Photosynthetic pigments did not change with variations in either visible or UV light. After adaptation for 24 hours, photosynthetic rate measured under conditions of essentially no UV was approximately twice that measured under near ambient UV conditions. Results of photosynthesis-irradiance experiments indicate that photosynthetic efficiencies (α), maximum photosynthetic rates (P max ) and the index of inhibition (I b ) were inversely related to UV levels, probably due at least in part to the loss of chlorophyll a

  4. Improvement in extracellular protease production by the marine antarctic yeast Rhodotorula mucilaginosa L7.

    Science.gov (United States)

    Chaud, Luciana C S; Lario, Luciana D; Bonugli-Santos, Rafaella C; Sette, Lara D; Pessoa Junior, Adalberto; Felipe, Maria das Graças de A

    2016-12-25

    Microorganisms from extreme and restrictive eco systems, such as the Antarctic continent, are of great interest due to their ability to synthesize products of commercial value. Among these, enzymes from psychrotolerant and psychrophilic microorganisms offer potential economical benefits due to their high activity at low and moderate temperatures. The cold adapted yeast Rhodotorula mucilaginosa L7 was selected out of 97 yeasts isolated from Antarctica as having the highest extracellular proteolytic activity in preliminary tests. The present study was aimed at evaluating the effects of nutrient composition (peptone, rice bran extract, ammonium sulfate, sodium chloride) and physicochemical parameters (temperature and pH) on its proteolytic activity. A 2 6-2 fractional factorial design experiment followed by a central composite design (CCD 2 3 ) was performed to optimize the culture conditions and improve the extracellular proteolytic activity. The results indicated that the presence of peptone in the medium was the most influential factor in protease production. Enzymatic activity was enhanced by the interaction between low glucose and peptone concentrations. The optimization of culture conditions with the aid of mathematical modeling enabled a c. 45% increase in proteolytic activity and at the same time reduced the amount of glucose and peptone required for the culture. Thus culture conditions established in this work may be employed in the biotechnological production of this protease. Copyright © 2016 Elsevier B.V. All rights reserved.

  5.  Marine derived dinoflagellates in Antarctic saline lakes: Community composition and annual dynamics

    DEFF Research Database (Denmark)

    Rengefors, K.; Layborn-Parry, L.; Logares, R.

    2008-01-01

    polar dinoflagellate community, and not freshwater species. Polarella glacialis Montresor, Procaccini et Stoecker, a bipolar marine species, was for the first time described in a lake habitat and was an important phototrophic component in the higher salinity lakes. In the brackish lakes, we found a new...... sibling species to the brackish-water species Scrippsiella hangoei (J. Schiller) J. Larsen, previously observed only in the Baltic Sea....

  6. Precipitation of ikaite crystals in Antarctic marine sediments: implications from pore water geochemistry

    Science.gov (United States)

    Lu, Z.; Kennedy, H.; Rickaby, R. E.; Georg, B.; Shaw, S.; Lennie, A.; Pancost, R. D.

    2008-12-01

    Ikaite is a calcium carbonate hexahydrate (CaCO3•6H20) considered to be stable only at low temperatures. It has been found in form of tufa tower at locations where alkaline water mixes with water masses enriched in calcium (e.g. Ikka Fjord, Mono Lake). Large euhedral single crystals of ikaite were also recovered in marine sediments, associated with organic matter degradation, anaerobic oxidation of methane (AOM) and sulfate reduction. The hydration water in the ikaite crystals were demonstrated to record the oxygen isotope composition of the water from which they precipitated. Such a characteristic may allow using ikaite to reconstruct the ice volume in the past. For this purpose, the controls on its precipitation in the sediment column need to be investigated which is the main goal of this study. U.S. Antarctica Program cruise NBP0703 collected two cores with ikaite crystals at Antarctica Peninsula (Bransfield Strait and Firth of Tay). We determined major cation/anion concentrations, dissolved inorganic carbon (DIC) and δ13C composition of DIC in the pore waters in these two cores. Strong organic matter degradation or AOM in both cores results in quick consumption of sulfate in shallow part of the cores (SMT at around 3m).Rapid build-up of DIC is accompanied by the sharp decrease of dissolved calcium in the top 5m. Large variations were observed in δ13CDIC values (-20‰ to +13‰). The δ13C of ikaite in two cores were distinctive from each other (-19‰ and +4‰) corresponding to the DIC pools at different depths. The down core saturation state of the ikaite was modeled in PHREEQC based on the pore water chemistry, and the results are consistent with carbon isotope data, suggesting that these large crystals very likely formed within a narrow depth interval and a short time period (given high sedimentation rates of 0.5-1 cm/yr in this area).

  7. Transmission of Ranavirus between Ectothermic Vertebrate Hosts

    Science.gov (United States)

    Brenes, Roberto; Gray, Matthew J.; Waltzek, Thomas B.; Wilkes, Rebecca P.; Miller, Debra L.

    2014-01-01

    Transmission is an essential process that contributes to the survival of pathogens. Ranaviruses are known to infect different classes of lower vertebrates including amphibians, fishes and reptiles. Differences in the likelihood of infection among ectothermic vertebrate hosts could explain the successful yearlong persistence of ranaviruses in aquatic environments. The goal of this study was to determine if transmission of a Frog Virus 3 (FV3)-like ranavirus was possible among three species from different ectothermic vertebrate classes: Cope’s gray treefrog (Hyla chrysoscelis) larvae, mosquito fish (Gambusia affinis), and red-eared slider (Trachemys scripta elegans). We housed individuals previously exposed to the FV3-like ranavirus with naïve (unexposed) individuals in containers divided by plastic mesh screen to permit water flow between subjects. Our results showed that infected gray treefrog larvae were capable of transmitting ranavirus to naïve larval conspecifics and turtles (60% and 30% infection, respectively), but not to fish. Also, infected turtles and fish transmitted ranavirus to 50% and 10% of the naïve gray treefrog larvae, respectively. Nearly all infected amphibians experienced mortality, whereas infected turtles and fish did not die. Our results demonstrate that ranavirus can be transmitted through water among ectothermic vertebrate classes, which has not been reported previously. Moreover, fish and reptiles might serve as reservoirs for ranavirus given their ability to live with subclinical infections. Subclinical infections of ranavirus in fish and aquatic turtles could contribute to the pathogen’s persistence, especially when highly susceptible hosts like amphibians are absent as a result of seasonal fluctuations in relative abundance. PMID:24667325

  8. Transmission of ranavirus between ectothermic vertebrate hosts.

    Directory of Open Access Journals (Sweden)

    Roberto Brenes

    Full Text Available Transmission is an essential process that contributes to the survival of pathogens. Ranaviruses are known to infect different classes of lower vertebrates including amphibians, fishes and reptiles. Differences in the likelihood of infection among ectothermic vertebrate hosts could explain the successful yearlong persistence of ranaviruses in aquatic environments. The goal of this study was to determine if transmission of a Frog Virus 3 (FV3-like ranavirus was possible among three species from different ectothermic vertebrate classes: Cope's gray treefrog (Hyla chrysoscelis larvae, mosquito fish (Gambusia affinis, and red-eared slider (Trachemys scripta elegans. We housed individuals previously exposed to the FV3-like ranavirus with naïve (unexposed individuals in containers divided by plastic mesh screen to permit water flow between subjects. Our results showed that infected gray treefrog larvae were capable of transmitting ranavirus to naïve larval conspecifics and turtles (60% and 30% infection, respectively, but not to fish. Also, infected turtles and fish transmitted ranavirus to 50% and 10% of the naïve gray treefrog larvae, respectively. Nearly all infected amphibians experienced mortality, whereas infected turtles and fish did not die. Our results demonstrate that ranavirus can be transmitted through water among ectothermic vertebrate classes, which has not been reported previously. Moreover, fish and reptiles might serve as reservoirs for ranavirus given their ability to live with subclinical infections. Subclinical infections of ranavirus in fish and aquatic turtles could contribute to the pathogen's persistence, especially when highly susceptible hosts like amphibians are absent as a result of seasonal fluctuations in relative abundance.

  9. Psychrotrophic metal tolerant bacteria for mobilisation of metals in Antarctic waters

    Digital Repository Service at National Institute of Oceanography (India)

    Gonsalves, M.J.B.D.

    Cold tolerant psychrotrophic bacteria abound in the Antarctic waters. While Antarctic krills are known to concentrate heavy metals at ppm levels, psychrotrophic bacteria from Antarctic fresh and marine waters have been reported to tolerate them...

  10. Heavy metals in sediments and soft tissues of the Antarctic clam Laternula elliptica: more evidence as a possible biomonitor of coastal marine pollution at high latitudes?

    Science.gov (United States)

    Vodopivez, Cristian; Curtosi, Antonio; Villaamil, Edda; Smichowski, Patricia; Pelletier, Emilien; Mac Cormack, Walter P

    2015-01-01

    Studies on metal contamination in 25 de Mayo Island, Antarctica, yielded controversial results. In this work, we analyzed Antarctic marine sediments and Antarctic clam (Laternula elliptica) tissues to investigate the possible use of this mollusk as a biomonitor of metals and to identify the sources of metal pollution. Different types of paint from several buildings from Carlini Station were examined to assess their contribution to the local and random metal pollution. Five sediment samples, 105 L. elliptica specimens (40.2-78.0mm length) and four types of paint were analyzed to quantify Cd, Cr, Cu, Fe, Mn, Pb and Zn using inductively coupled plasma-optical emission spectrometry. Metal concentrations in sediments were lower than the global averages of the earth's crust, with the exception of Cd and Cu. These results were related to the contribution of the local fresh-water runoff. The different varieties of paint showed low levels of Cu, Mn, Fe and Zn, whereas a broad range of values were found in the case of Cr and Pb (20-15,100 μg·g(-1) and 153-115,500 μg·g(-1) respectively). The remains of the paint would be responsible for the significant increases in Cr and Pb which are randomly detected by us and by other authors. High levels of Fe and Cd, in comparison to other Antarctic areas, appear to be related to the terrigenous materials transported by the local streams. Accumulation indexes suggested that kidney tissue from L. elliptica could be an adequate material for biomonitoring pollution with Cd, Zn and probably also Pb. In general, relationships between size and metal contents reported by other authors were not verified, suggesting that this issue should be revised. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming

    Science.gov (United States)

    Gunderson, Alex R.; Stillman, Jonathon H.

    2015-01-01

    Global warming is increasing the overheating risk for many organisms, though the potential for plasticity in thermal tolerance to mitigate this risk is largely unknown. In part, this shortcoming stems from a lack of knowledge about global and taxonomic patterns of variation in tolerance plasticity. To address this critical issue, we test leading hypotheses for broad-scale variation in ectotherm tolerance plasticity using a dataset that includes vertebrate and invertebrate taxa from terrestrial, freshwater and marine habitats. Contrary to expectation, plasticity in heat tolerance was unrelated to latitude or thermal seasonality. However, plasticity in cold tolerance is associated with thermal seasonality in some habitat types. In addition, aquatic taxa have approximately twice the plasticity of terrestrial taxa. Based on the observed patterns of variation in tolerance plasticity, we propose that limited potential for behavioural plasticity (i.e. behavioural thermoregulation) favours the evolution of greater plasticity in physiological traits, consistent with the ‘Bogert effect’. Finally, we find that all ectotherms have relatively low acclimation in thermal tolerance and demonstrate that overheating risk will be minimally reduced by acclimation in even the most plastic groups. Our analysis indicates that behavioural and evolutionary mechanisms will be critical in allowing ectotherms to buffer themselves from extreme temperatures. PMID:25994676

  12. Development of a model to assess masking potential for marine mammals by the use of airguns in Antarctic waters (abstract)

    NARCIS (Netherlands)

    Wittekind, D.; Tougaard, J.; Stilz, P.; Dähne, M.; Lucke, K.; Clark, C.W.; Benda-Beckmann, A.M. von; Ainslie, M.A.; Siebert, U.

    2013-01-01

    Functional marine mammal acoustic communication evolved under natural ambient noise levels, which makes communication vulnerable to intense, anthropogenic noise sources. We consider the potential long-range reduction effects of airgun noise on marine mammal communication range. During the

  13. Ultraviolet radiation response of two heterotropy Antarctic marine bacterial; Respuesta a la radiacion ultravioleta de dos cepas bacterianas marinas heterotrofas antarticas

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Edgardo A [Buenos Aires Univ. (Argentina). Facultad de Farmacia y Bioquimica; Ferreyra, Gustavo A; Mac Cormack, Walter P [Direccion Nacional del Antartico, Buenos Aires (Argentina). Instituto Antartico Argentino

    2004-07-01

    Two Antarctic marine bacterial strains, were exposed to different irradiance of ultraviolet (UV) solar radiation using several experimental protocols and interferential filters. Results showed that both, UV-A and UV-B radiation produce deleterious effects on two tested bacterial strains. The mortality values under UVB treatments were higher than those observed under UVA treatments. UVvi strain proved to be more resistant to UV radiation than the UVps strain. (author) [Spanish] Dos cepas marinas antarticas fueron expuestas a diferentes irradiancias de radiacion solar ultravioleta (UV) utilizando diferentes protocolos experimentales y filtros interferenciales. Los resultados mostraron que tanto la radiacion UV-A como UV-B produce efectos deletereos sobre las dos cepas bacterianas analizadas. Los valores de mortalidad bajo tratamiento UV-B fueron mayores que los observados bajo tratamiento UV-A. La cepa UVvi mostro mayor resistencia a la radiacion UV que la cepa UVps. (autor)

  14. Integration of airborne altimetry and in situ radar measurements to estimate marine ice thickness beneath the Larsen C ice shelf, Antarctic Peninsula

    Science.gov (United States)

    McGrath, D.; Steffen, K.; Rodriguez Lagos, J.

    2010-12-01

    Observed atmospheric and oceanic warming is driving significant retreat and / or collapse of ice shelves along the Antarctic Peninsula totaling over 25,000 km2 in the past five decades. Basal melting of meteoric ice can occur near the grounding line of deep glacier inflows if the ocean water is above the pressure melting point. Buoyant meltwater will develop thermohaline circulation, rising beneath the ice shelf, where it may become supercooled and subsequently refreeze in ice draft minima. Marine ice, due to its warm and thus relatively viscous nature, is hypothesized to suture parallel flow bands, increasing ice shelf stability by arresting fracture propagation and controlling iceberg calving dimensions. Thus efforts to model ice shelf stability require accurate estimates of marine ice location and thickness. Ice thickness of a floating ice shelf can be determined in two manners: (1) from measurements of ice elevation above sea level and the calculation of ice thickness from assumptions of hydrostatic equilibrium, and (2) from radar echo measurements of the ice-water interface. Marine ice can confound the latter because its high dielectric constant and strong absorptive properties attenuate the radar energy, often preventing a return signal from the bottom of the ice shelf. These two methods are complementary for determining the marine ice component though because positive anomalies in (1) relative to (2) suggest regions of marine ice accretion. Nearly 350 km of ice penetrating radar (25 MHz) surveys were collected on the Larsen C ice shelf, in conjunction with kinematic GPS measurements and collocated with surface elevation data from the NASA Airborne Topographic Mapper (ATM) as part of the ICE Bridge mission in 2009. Basal ice topography and total ice thickness is accurately mapped along the survey lines and compared with calculated ice thickness from both the kinematic GPS and ATM elevation data. Positive anomalies are discussed in light of visible imagery and

  15. Impact of marine debris on Antarctic fur seals Arctocephalus gazella at Cape Shirreff: diet dependent ingestion and entanglement

    NARCIS (Netherlands)

    Bravo Rebolledo, Elisa; Franeker, van J.A.

    2015-01-01

    For several decades it has been known that plastics in the marine environment can harm marine organisms, most visibly birds, turtles and mammals (Shomura and Yoshida, 1985). These animals can become entangled in this synthetic debris and can ingest macro- and micro-plastics. Recently, increased

  16. Development of a model to assess masking potential for marine mammals by the use of air guns in Antarctic waters

    NARCIS (Netherlands)

    Wittekind, Dietrich; Tougaard, Jakob; Stilz, Peter; Dähne, Michael; Clark, Christopher W.; Lucke, K.; Benda-Beckmann, von Sander; Ainslie, Michael A.; Siebert, Ursula

    2016-01-01

    We estimated the long-range effects of air gun array noise on marine mammal communication ranges in the Southern Ocean. Air gun impulses are subject to significant distortion during propagation, potentially resulting in a quasi- continuous sound. Propagation modeling to estimate the received

  17. Development of a model to assess masking potential for marine mammals by the use of air guns in Antarctic waters

    NARCIS (Netherlands)

    Wittekind, D.; Tougaard, J.; Stilz, P.; Dähne, M.; Clark, C.W.; Lucke, K.; Benda-Beckmann, A.M. von; Ainslie, M.A.; Siebert, U.

    2016-01-01

    We estimated the long-range effects of air gun array noise on marine mammal communication ranges in the Southern Ocean. Air gun impulses are subject to significant distortion during propagation, potentially resulting in a quasi- continuous sound. Propagation modeling to estimate the received

  18. Neither elevated nor reduced CO2 affects the photophysiological performance of the marine Antarctic diatom Chaetoceros brevis

    NARCIS (Netherlands)

    Boelen, Peter; de Poll, Willem H. van; van der Strate, Han J.; Neven, Ika A.; Beardall, John; Buma, Anita G. J.

    2011-01-01

    Enhanced or reduced pCO(2) (partial pressure of CO2) may affect the photosynthetic performance of marine microalgae since changes in pCO(2) can influence the activity of carbon concentrating mechanisms, modulate cellular RuBisCO levels or alter carbon uptake efficiency. In the present study we

  19. Environmental contamination in Antarctic ecosystems.

    Science.gov (United States)

    Bargagli, R

    2008-08-01

    Although the remote continent of Antarctica is perceived as the symbol of the last great wilderness, the human presence in the Southern Ocean and the continent began in the early 1900s for hunting, fishing and exploration, and many invasive plant and animal species have been deliberately introduced in several sub-Antarctic islands. Over the last 50 years, the development of research and tourism have locally affected terrestrial and marine coastal ecosystems through fuel combustion (for transportation and energy production), accidental oil spills, waste incineration and sewage. Although natural "barriers" such as oceanic and atmospheric circulation protect Antarctica from lower latitude water and air masses, available data on concentrations of metals, pesticides and other persistent pollutants in air, snow, mosses, lichens and marine organisms show that most persistent contaminants in the Antarctic environment are transported from other continents in the Southern Hemisphere. At present, levels of most contaminants in Antarctic organisms are lower than those in related species from other remote regions, except for the natural accumulation of Cd and Hg in several marine organisms and especially in albatrosses and petrels. The concentrations of organic pollutants in the eggs of an opportunistic top predator such as the south polar skua are close to those that may cause adverse health effects. Population growth and industrial development in several countries of the Southern Hemisphere are changing the global pattern of persistent anthropogenic contaminants and new classes of chemicals have already been detected in the Antarctic environment. Although the Protocol on Environmental Protection to the Antarctic Treaty provides strict guidelines for the protection of the Antarctic environment and establishes obligations for all human activity in the continent and the Southern Ocean, global warming, population growth and industrial development in countries of the Southern

  20. Activities of the training vessel Umitaka-maru (KARE-15; UM-11-07 of the Tokyo University of Marine Science and Technology during the 53rd Japanese Antarctic Research Expedition in 2011/2012

    Directory of Open Access Journals (Sweden)

    Masato Moteki

    2015-11-01

    Full Text Available The training vessel Umitaka-maru of the Tokyo University of Marine Science and Technology (TUMSAT undertook a marine science cruise in the Indian sector of the Southern Ocean during the 2011/2012 austral summer. During the cruise, TUMSAT conducted five different collaborative research projects. These included two phase-VIII Japanese Antarctic Research Expedition (JARE-52 to -57 projects: "Responses of Antarctic Marine Ecosystems to Global Environmental Changes with Carbonate Systems", which is the sub-theme of the prioritized research project "Exploring Global Warming from Antarctica"; and the ordinary research project "Studies on Plankton Community Structure and Environment Parameters in the Southern Ocean". The other three collaborative research projects were those undertaken in conjunction with (1 the National Institute of Polar Research, entitled "Environment and Ecosystem Changes in the Southern Ocean"; (2 the Japan Agency for Marine-Earth Science and Technology (JAMSTEC, entitled "Deployment of the Southern Ocean Buoy" ; and (3 with Hokkaido University, entitled "Studies on Dynamics of Antarctic Bottom Water". The Umitaka-maru departed from Fremantle, Australia, on 27 December 2011, sailed to the study area around the marginal sea ice zone (mainly along 110°E and 140°E, and returned to Hobart, Australia, on 1 February 2012. The participants performed various net castings to qualitatively evaluate the vertical distribution of plankton communities, made physical observations, and measured chemical parameters. They also retrieved a year-round mooring that had been deployed the previous year, retrieved two surface drifting buoys that had been released by the ice breaker Shirase, and deployed a JAMSTEC buoy (m-TRITON. In addition, several acidified culture experiments using pteropods were conducted on board.

  1. Comparative aspects of hypoxia tolerance of the ectothermic vertebrate heart

    DEFF Research Database (Denmark)

    Gesser, Hans; Overgaard, Johannes

    2009-01-01

    This chapter reviews cardiac contractile performance and its regulation during hypoxia/anoxia with regard to cellular metabolism and energy state, in particular hypoxia-tolerant ectothermic vertebrates. Overall the contractile performance of the hypoxic isolated heart muscle varies in a way...

  2. A First Look at Oxygen and Silicon Isotope Variations in Diatom Silica from a Pliocene Antarctic Marine Sediment Core

    Science.gov (United States)

    Abbott, T.; Dodd, J. P.; Hackett, H.; Scherer, R. P.

    2016-02-01

    Coupled oxygen (δ18O) and silicon (δ30Si) isotope variations in diatom silica (opal-A) are increasingly used as a proxy to reconstruct paleoenvironmental conditions (water temperatures, water mass mixing, nutrient cycling) in marine environments. Diatom silica is a particularly significant paleoenvironmental proxy in high latitude environments, such as the Southern Ocean, where diatom blooms are abundant and diatom frustules are well preserved in the sediment. The Andrill-1B (AND-1B) sediment core from the Ross Sea (Antarctica) preserves several Pliocene ( 4.5 Ma) age diatomite units. Here we present preliminary δ18O and δ30Si values for a diatomite subunit in the AND-1B sediment core. Initial isotope values for the AND-1B diatoms silica record relatively high variability (range δ18O: 36.3‰ to 39.9‰) that could be interpreted as large-scale changes in the water temperature and/or freshwater mixing in the Ross Sea; however, a significant concern with marine sediment of this age is isotope fractionation during diagenesis and the potential formation of opal-CT lepispheres. The effects of clay contamination on the diatom silica δ18O values have been addressed through sample purification and quantified through chemical and physical analyses of the diatom silica. The isotopic effects of opal-CT are not as clearly understood and more difficult to physically separate from the primary diatom silica. In order to better understand the isotope variations in the AND-1B diatoms, we also evaluated silicon and oxygen isotope fractionation during the transition from opal-A to opal-CT in a controlled laboratory experiment. Opal-A from cultured marine diatoms (Thalassiosira weissflogii) was subjected to elevated temperatures (150°C) in acid digestion vessels for 4 weeks to initiate opal-CT precipitation. Quantifying the effects of opal-CT formation on δ18O and δ30Si variations in biogenic silica improves our understanding of the use of diatom silica isotope values a

  3. Can Camera Traps Monitor Komodo Dragons a Large Ectothermic Predator?

    OpenAIRE

    Ariefiandy, Achmad; Purwandana, Deni; Seno, Aganto; Ciofi, Claudio; Jessop, Tim S.

    2013-01-01

    Camera trapping has greatly enhanced population monitoring of often cryptic and low abundance apex carnivores. Effectiveness of passive infrared camera trapping, and ultimately population monitoring, relies on temperature mediated differences between the animal and its ambient environment to ensure good camera detection. In ectothermic predators such as large varanid lizards, this criterion is presumed less certain. Here we evaluated the effectiveness of camera trapping to potentially monitor...

  4. Activities of the training vessel Umitaka-maru (KARE16 ; UM-12-08 of the Tokyo University of Marine Science and Technology during the 54th Japanese Antarctic Research Expedition in 2012/2013

    Directory of Open Access Journals (Sweden)

    Yujiro Kitade

    2016-07-01

    Full Text Available A marine science cruise was undertaken in the Indian sector of the Southern Ocean during the 2012/2013 austral summer on the training vessel Umitaka-maru (KARE16; UM-12-08 of the Tokyo University of Marine Science and Technology (TUMSAT. A primary aim of the cruise was to carry out a TUMSAT and National Institute of Polar Research (NIPR collaborative project commissioned by the Ministry of Education, Culture, Sports, Science and Technology (MEXT, entitled“Japanese Antarctic Research Expedition (JARE Routine Observation: Physical and Chemical Oceanography”. In addition to the MEXT-commissioned project, two TUMSAT-NIPR collaborative projects were conducted: 1“Studies on Plankton Community Structure and Environment Parameters in the Southern Ocean”, which is one of the original research projects of the JARE phase VIII (JAREs-52 to -57 projects; and 2“Environment and Ecosystem Changes in the Southern Ocean”. The Umitaka-maru departed from Fremantle, Australia, on 31 December 2012, sailed to the study area situated along 110°E in the marginal sea ice zone, and returned to Hobart, Australia, on 24 January 2013. Detailed properties of the Antarctic bottom water were revealed from physical and chemical oceanographic observations collected using a conductivity-temperature-depth profiler deployed to near the seafloor in the marginal ice zone. In addition, participants performed various net castings to qualitatively evaluate the vertical distribution of plankton communities, and deployed two year-round mooring arrays to assess the dynamics of Antarctic bottom water.

  5. The changing form of Antarctic biodiversity.

    Science.gov (United States)

    Chown, Steven L; Clarke, Andrew; Fraser, Ceridwen I; Cary, S Craig; Moon, Katherine L; McGeoch, Melodie A

    2015-06-25

    Antarctic biodiversity is much more extensive, ecologically diverse and biogeographically structured than previously thought. Understanding of how this diversity is distributed in marine and terrestrial systems, the mechanisms underlying its spatial variation, and the significance of the microbiota is growing rapidly. Broadly recognizable drivers of diversity variation include energy availability and historical refugia. The impacts of local human activities and global environmental change nonetheless pose challenges to the current and future understanding of Antarctic biodiversity. Life in the Antarctic and the Southern Ocean is surprisingly rich, and as much at risk from environmental change as it is elsewhere.

  6. Water Circulation and Marine Environment in the Antarctic Traced by Speciation of 129I and 127I

    DEFF Research Database (Denmark)

    Xing, Shan; Hou, Xiaolin; Aldahan, Ala

    2017-01-01

    Emissions of anthropogenic 129I from human nuclear activities are now detected in the surface water of the Antarctic seas. Surface seawater samples from the Drake Passage, Bellingshausen, Amundsen, and Ross Seas were analyzed for total 129I and 127I, as well as for iodide and iodate of these two....... The iodine distribution patterns provide useful information on surface water transport and mixing that are vital for better understanding of the Southern Oceans effects on the global climate change. The results indicate multiple spatial interactions between the Antarctic Circumpolar Current (ACC......) and Antarctic Peninsula Coastal Current (APCC). These interactions happen in restricted circulation pathways that may partly relate to glacial melting and icebergs transport. Biological activity during the warm season should be one of the key factors controlling the reduction of iodate in the coastal water...

  7. Summer diet of the Salvin's prion at sub-Antarctic Marion Island

    African Journals Online (AJOL)

    1988-02-14

    Feb 14, 1988 ... Thirty-nine food samples were collected from Salvin's prions Pachyptila salvini at sub-Antarctic Marion Island,. Prince Edward Islands. ..... guide to foraging methods used by marine birds in. Antarctic and sub-Antarctic seas. BIOMASS Handbook. 24: 1-22. GRINDLEY, J.R. & LANE, S.B. 1979. Zooplankton.

  8. Isolation and characterization of Campylobacter spp. from Antarctic fur seals (Arctocephalus gazella) at Deception Island, Antarctica.

    Science.gov (United States)

    García-Peña, F J; Pérez-Boto, D; Jiménez, C; San Miguel, E; Echeita, A; Rengifo-Herrera, C; García-Párraga, D; Ortega-Mora, L M; Pedraza-Díaz, S

    2010-09-01

    The presence of Campylobacter spp. was investigated in 41 Antarctic fur seals (Arctocephalus gazella) and 9 Weddell seals (Leptonychotes weddellii) at Deception Island, Antarctica. Infections were encountered in six Antarctic fur seals. The isolates, the first reported from marine mammals in the Antarctic region, were identified as Campylobacter insulaenigrae and Campylobacter lari.

  9. Transcriptome of the Antarctic brooding gastropod mollusc Margarella antarctica.

    Science.gov (United States)

    Clark, Melody S; Thorne, Michael A S

    2015-12-01

    454 RNA-Seq transcriptome data were generated from foot tissue of the Antarctic brooding gastropod mollusc Margarella antarctica. A total of 6195 contigs were assembled de novo, providing a useful resource for researchers with an interest in Antarctic marine species, phylogenetics and mollusc biology, especially shell production. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Antarctic science

    Science.gov (United States)

    Summerhayes, Colin

    Once upon a time, dinosaurs roamed Antarctica and swam in its seas. Since then, life evolved as the climate cooled into the ice ages. Life will no doubt continue to evolve there as the globe now warms. But nowadays, humans are having a profound and direct effect on life in Antarctica, the sub-Antarctic islands, and the surrounding Southern Ocean, which are being invaded by a wide range of alien species including microbes, algae, fungi, bryophytes, land plants, invertebrates, fish, birds, and mammals.

  11. The changing form of Antarctic biodiversity

    OpenAIRE

    Chown, Steven L.; Clarke, Andrew; Fraser, Ceridwen I.; Cary, S. Craig; Moon, Katherine L.; McGeoch, Melodie A.

    2015-01-01

    Antarctic biodiversity is much more extensive, ecologically diverse and biogeographically structured than previously thought. Understanding of how this diversity is distributed in marine and terrestrial systems, the mechanisms underlying its spatial variation, and the significance of the microbiota is growing rapidly. Broadly recognizable drivers of diversity variation include energy availability and historical refugia. The impacts of local human activities and global environmental change non...

  12. Climate change, multiple stressors, and the decline of ectotherms.

    Science.gov (United States)

    Rohr, Jason R; Palmer, Brent D

    2013-08-01

    Climate change is believed to be causing declines of ectothermic vertebrates, but there is little evidence that climatic conditions associated with declines have exceeded critical (i.e., acutely lethal) maxima or minima, and most relevant studies are correlative, anecdotal, or short-term (hours). We conducted an 11-week factorial experiment to examine the effects of temperature (22 °C or 27 °C), moisture (wet or dry), and atrazine (an herbicide; 0, 4, 40, 400 μg/L exposure as embryos and larvae) on the survival, growth, behavior, and foraging rates of postmetamorphic streamside salamanders (Ambystoma barbouri), a species of conservation concern. The tested climatic conditions were between the critical maxima and minima of streamside salamanders; thus, this experiment quantified the long-term effects of climate change within the noncritical range of this species. Despite a suite of behavioral adaptations to warm and dry conditions (e.g., burrowing, refuge use, huddling with conspecifics, and a reduction in activity), streamside salamanders exhibited significant loss of mass and significant mortality in all but the cool and moist conditions, which were closest to the climatic conditions in which they are most active in nature. A temperature of 27 °C represented a greater mortality risk than dry conditions; death occurred rapidly at this temperature and more gradually under cool and dry conditions. Foraging decreased under dry conditions, which suggests there were opportunity costs to water conservation. Exposure to the herbicide atrazine additively decreased water-conserving behaviors, foraging efficiency, mass, and time to death. Hence, the hypothesis that moderate climate change can cause population declines is even more plausible under scenarios with multiple stressors. These results suggest that climate change within the noncritical range of species and pollution may reduce individual performance by altering metabolic demands, hydration, and foraging effort

  13. Ocean acidification exerts negative effects during warming conditions in a developing Antarctic fish.

    Science.gov (United States)

    Flynn, Erin E; Bjelde, Brittany E; Miller, Nathan A; Todgham, Anne E

    2015-01-01

    Anthropogenic CO2 is rapidly causing oceans to become warmer and more acidic, challenging marine ectotherms to respond to simultaneous changes in their environment. While recent work has highlighted that marine fishes, particularly during early development, can be vulnerable to ocean acidification, we lack an understanding of how life-history strategies, ecosystems and concurrent ocean warming interplay with interspecific susceptibility. To address the effects of multiple ocean changes on cold-adapted, slowly developing fishes, we investigated the interactive effects of elevated partial pressure of carbon dioxide (pCO2) and temperature on the embryonic physiology of an Antarctic dragonfish (Gymnodraco acuticeps), with protracted embryogenesis (∼10 months). Using an integrative, experimental approach, our research examined the impacts of near-future warming [-1 (ambient) and 2°C (+3°C)] and ocean acidification [420 (ambient), 650 (moderate) and 1000 μatm pCO2 (high)] on survival, development and metabolic processes over the course of 3 weeks in early development. In the presence of increased pCO2 alone, embryonic mortality did not increase, with greatest overall survival at the highest pCO2. Furthermore, embryos were significantly more likely to be at a later developmental stage at high pCO2 by 3 weeks relative to ambient pCO2. However, in combined warming and ocean acidification scenarios, dragonfish embryos experienced a dose-dependent, synergistic decrease in survival and developed more slowly. We also found significant interactions between temperature, pCO2 and time in aerobic enzyme activity (citrate synthase). Increased temperature alone increased whole-organism metabolic rate (O2 consumption) and developmental rate and slightly decreased osmolality at the cost of increased mortality. Our findings suggest that developing dragonfish are more sensitive to ocean warming and may experience negative physiological effects of ocean acidification only in

  14. Consistent Richness-Biomass Relationship across Environmental Gradients in a Marine Macroalgal-Dominated Subtidal Community on the Western Antarctic Peninsula.

    Directory of Open Access Journals (Sweden)

    Nelson Valdivia

    Full Text Available Biodiversity loss has spurred the biodiversity-ecosystem functioning research over a range of ecosystems. In Antarctica, however, the relationship of taxonomic and functional diversity with ecosystem properties (e.g., community biomass has received less attention, despite the presence of sharp and dynamic environmental stress gradients that might modulate these properties. Here, we investigated whether the richness-biomass relationship in macrobenthic subtidal communities is still apparent after accounting for environmental stress gradients in Fildes Bay, King George Island, Antarctica. Measurements of biomass of mobile and sessile macrobenthic taxa were conducted in the austral summer 2013/4 across two environmental stress gradients: distance from nearest glaciers and subtidal depth (from 5 to 30 m. In general, community biomass increased with distance from glaciers and water depth. However, generalised additive models showed that distance from glaciers and depth accounted for negligible proportions of variation in the number of functional groups (i.e., functional richness and community biomass when compared to taxonomic richness. Functional richness and community biomass were positive and saturating functions of taxonomic richness. Large endemic, canopy-forming brown algae of the order Desmarestiales dominated the community biomass across both gradients. Accordingly, differences in the composition of taxa accounted for a significant and large proportion (51% of variation in community biomass in comparison with functional richness (10%. Our results suggest that the environmental factors here analysed may be less important than biodiversity in shaping mesoscale (several km biomass patterns in this Antarctic system. We suggest that further manipulative, hypothesis-driven research should address the role of biodiversity and species' functional traits in the responses of Antarctic subtidal communities to environmental variation.

  15. Reconsidering connectivity in the sub-Antarctic.

    Science.gov (United States)

    Moon, Katherine L; Chown, Steven L; Fraser, Ceridwen I

    2017-11-01

    Extreme and remote environments provide useful settings to test ideas about the ecological and evolutionary drivers of biological diversity. In the sub-Antarctic, isolation by geographic, geological and glaciological processes has long been thought to underpin patterns in the region's terrestrial and marine diversity. Molecular studies using increasingly high-resolution data are, however, challenging this perspective, demonstrating that many taxa disperse among distant sub-Antarctic landmasses. Here, we reconsider connectivity in the sub-Antarctic region, identifying which taxa are relatively isolated, which are well connected, and the scales across which this connectivity occurs in both terrestrial and marine systems. Although many organisms show evidence of occasional long-distance, trans-oceanic dispersal, these events are often insufficient to maintain gene flow across the region. Species that do show evidence of connectivity across large distances include both active dispersers and more sedentary species. Overall, connectivity patterns in the sub-Antarctic at intra- and inter-island scales are highly complex, influenced by life-history traits and local dynamics such as relative dispersal capacity and propagule pressure, natal philopatry, feeding associations, the extent of human exploitation, past climate cycles, contemporary climate, and physical barriers to movement. An increasing use of molecular data - particularly genomic data sets that can reveal fine-scale patterns - and more effective international collaboration and communication that facilitates integration of data from across the sub-Antarctic, are providing fresh insights into the processes driving patterns of diversity in the region. These insights offer a platform for assessing the ways in which changing dispersal mechanisms, such as through increasing human activity and changes to wind and ocean circulation, may alter sub-Antarctic biodiversity patterns in the future. © 2017 Cambridge

  16. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size.

    Directory of Open Access Journals (Sweden)

    Richard B King

    Full Text Available Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females and annual growth increments of individuals of unknown age (1,152 males, 730 females. We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631-820 mm snout-vent length in males and from 835-1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further

  17. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size

    Science.gov (United States)

    King, Richard B.

    2016-01-01

    Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631–820 mm snout-vent length in males and from 835–1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation. PMID

  18. Can camera traps monitor Komodo dragons a large ectothermic predator?

    Directory of Open Access Journals (Sweden)

    Achmad Ariefiandy

    Full Text Available Camera trapping has greatly enhanced population monitoring of often cryptic and low abundance apex carnivores. Effectiveness of passive infrared camera trapping, and ultimately population monitoring, relies on temperature mediated differences between the animal and its ambient environment to ensure good camera detection. In ectothermic predators such as large varanid lizards, this criterion is presumed less certain. Here we evaluated the effectiveness of camera trapping to potentially monitor the population status of the Komodo dragon (Varanus komodoensis, an apex predator, using site occupancy approaches. We compared site-specific estimates of site occupancy and detection derived using camera traps and cage traps at 181 trapping locations established across six sites on four islands within Komodo National Park, Eastern Indonesia. Detection and site occupancy at each site were estimated using eight competing models that considered site-specific variation in occupancy (ψand varied detection probabilities (p according to detection method, site and survey number using a single season site occupancy modelling approach. The most parsimonious model [ψ (site, p (site survey; ω = 0.74] suggested that site occupancy estimates differed among sites. Detection probability varied as an interaction between site and survey number. Our results indicate that overall camera traps produced similar estimates of detection and site occupancy to cage traps, irrespective of being paired, or unpaired, with cage traps. Whilst one site showed some evidence detection was affected by trapping method detection was too low to produce an accurate occupancy estimate. Overall, as camera trapping is logistically more feasible it may provide, with further validation, an alternative method for evaluating long-term site occupancy patterns in Komodo dragons, and potentially other large reptiles, aiding conservation of this species.

  19. Can camera traps monitor Komodo dragons a large ectothermic predator?

    Science.gov (United States)

    Ariefiandy, Achmad; Purwandana, Deni; Seno, Aganto; Ciofi, Claudio; Jessop, Tim S

    2013-01-01

    Camera trapping has greatly enhanced population monitoring of often cryptic and low abundance apex carnivores. Effectiveness of passive infrared camera trapping, and ultimately population monitoring, relies on temperature mediated differences between the animal and its ambient environment to ensure good camera detection. In ectothermic predators such as large varanid lizards, this criterion is presumed less certain. Here we evaluated the effectiveness of camera trapping to potentially monitor the population status of the Komodo dragon (Varanus komodoensis), an apex predator, using site occupancy approaches. We compared site-specific estimates of site occupancy and detection derived using camera traps and cage traps at 181 trapping locations established across six sites on four islands within Komodo National Park, Eastern Indonesia. Detection and site occupancy at each site were estimated using eight competing models that considered site-specific variation in occupancy (ψ)and varied detection probabilities (p) according to detection method, site and survey number using a single season site occupancy modelling approach. The most parsimonious model [ψ (site), p (site survey); ω = 0.74] suggested that site occupancy estimates differed among sites. Detection probability varied as an interaction between site and survey number. Our results indicate that overall camera traps produced similar estimates of detection and site occupancy to cage traps, irrespective of being paired, or unpaired, with cage traps. Whilst one site showed some evidence detection was affected by trapping method detection was too low to produce an accurate occupancy estimate. Overall, as camera trapping is logistically more feasible it may provide, with further validation, an alternative method for evaluating long-term site occupancy patterns in Komodo dragons, and potentially other large reptiles, aiding conservation of this species.

  20. Can Camera Traps Monitor Komodo Dragons a Large Ectothermic Predator?

    Science.gov (United States)

    Ariefiandy, Achmad; Purwandana, Deni; Seno, Aganto; Ciofi, Claudio; Jessop, Tim S.

    2013-01-01

    Camera trapping has greatly enhanced population monitoring of often cryptic and low abundance apex carnivores. Effectiveness of passive infrared camera trapping, and ultimately population monitoring, relies on temperature mediated differences between the animal and its ambient environment to ensure good camera detection. In ectothermic predators such as large varanid lizards, this criterion is presumed less certain. Here we evaluated the effectiveness of camera trapping to potentially monitor the population status of the Komodo dragon (Varanus komodoensis), an apex predator, using site occupancy approaches. We compared site-specific estimates of site occupancy and detection derived using camera traps and cage traps at 181 trapping locations established across six sites on four islands within Komodo National Park, Eastern Indonesia. Detection and site occupancy at each site were estimated using eight competing models that considered site-specific variation in occupancy (ψ)and varied detection probabilities (p) according to detection method, site and survey number using a single season site occupancy modelling approach. The most parsimonious model [ψ (site), p (site*survey); ω = 0.74] suggested that site occupancy estimates differed among sites. Detection probability varied as an interaction between site and survey number. Our results indicate that overall camera traps produced similar estimates of detection and site occupancy to cage traps, irrespective of being paired, or unpaired, with cage traps. Whilst one site showed some evidence detection was affected by trapping method detection was too low to produce an accurate occupancy estimate. Overall, as camera trapping is logistically more feasible it may provide, with further validation, an alternative method for evaluating long-term site occupancy patterns in Komodo dragons, and potentially other large reptiles, aiding conservation of this species. PMID:23527027

  1. Antarctic research today

    International Nuclear Information System (INIS)

    Hempel, G.

    1982-01-01

    With the appetite for living and dead natural resources, the political and economical interest concerning the Antarctic increases throughout the world. There are three interrelated main subjects accounting for the international interest: The shelf tectonic puzzle of the original continent of Gondwana, where the Antarctic is situated in the centre, between Australia, South Africa and South America, and the hopes concerning the existence of mineral resources under the ice of the Antarctic are based thereon. The Antarctic forms the biggest unified living space of the world. (orig.)

  2. Evolutionary adaptation of muscle power output to environmental temperature: force-velocity characteristics of skinned fibres isolated from antarctic, temperate and tropical marine fish.

    Science.gov (United States)

    Johnston, I A; Altringham, J D

    1985-09-01

    Single fast fibres were isolated from the myotomal muscles of icefish (Chaenocephalus aceratus Lönnberg, Antarctica), North Sea Cod (Gadus morhua L.) and Pacific Blue Marlin (Makaira nigricans Wakiya, Hawaii). Fibres were chemically skinned with the non-ionic detergent Brij-58. Maximum tensions (Po, kN m-2) developed at the characteristic body temperature of each species are 231 for icefish (-1 degree C), 187 for cod (8 degrees C) and 156 for marlin (20 degrees C). At 0 degree C Po is 7 times higher for fibres from the icefish than from the marlin. Fibres from icefish and cod failed to relax completely following activations at temperatures above approximately 12 degrees C. The resultant post-contraction force is associated with a proportional increase in stiffness, suggesting the formation of a population of Ca-insensitive cross bridges. At 10 degrees C there is little interspecific variation in unloaded contraction velocity (Vmax) among the three species. Vmax (muscle lengths s-1) at normal body temperatures are 0.9 for icefish (-1 degree C), 1.0 for cod (8 degrees C) and 3.4 for marlin (20 degrees C). The force-velocity (P-V) relationship becomes progressively more curved with increasing temperature for all three species. Maximum power output for the fast muscle fibres from the Antarctic species at -1 degree C is around 60% of that of the tropical fish at 20 degrees C. Evolutionary temperature compensation of muscle power output appears largely to involve differences in the ability of cross bridges to generate force.

  3. Lead isotopic signatures in Antarctic marine sediment cores: A comparison between 1 M HCl partial extraction and HF total digestion pre-treatments for discerning anthropogenic inputs

    International Nuclear Information System (INIS)

    Townsend, A.T.; Snape, I.; Palmer, A.S.; Seen, A.J.

    2009-01-01

    Sensitive analytical techniques are typically required when dealing with samples from Antarctica as even low concentrations of contaminants can have detrimental environmental effects. Magnetic Sector ICP-MS is an ideal technique for environmental assessment as it offers high sensitivity, multi-element capability and the opportunity to determine isotope ratios. Here we consider the Pb isotope record of five marine sediment cores collected from three sites in the Windmill Islands area of East Antarctica: Brown Bay adjacent to the current Australian station Casey, Wilkes near the abandoned US/Australian Station and McGrady Cove lying midway between the two. Two sediment pre-treatment approaches were considered, namely partial extraction with 1 M HCl and total dissolution involving HF. Lead isotope ratio measurements made following sediment partial extraction provided a more sensitive indication of Pb contamination than either Pb concentrations alone (irrespective of sample pre-treatment method) or isotope ratios made after HF digestion, offering greater opportunity for discrimination between impacted and natural/geogenic samples and sites. Over 90% of the easily extractable Pb from sediments near Casey was anthropogenic in origin, consisting of Pb from major Australian deposits. At Wilkes impact from discarded batteries with a unique isotopic signature was found to be a key source of Pb contamination to the marine environment with ∼ 70-80% of Pb being anthropogenic in origin. The country and source of origin of these batteries remain unknown. Little evidence was found suggesting contamination at Wilkes by Pb originating from the major US source, Missouri. No definitive assessment could be made regarding Pb impact at McGrady Cove as the collected sediment core was of insufficient depth. Although Pb isotope ratio signatures may indicate anthropogenic input, spatial concentration gradients at nearby Brown Bay suggest contamination at McGrady Cove is unlikely. We

  4. Antarctic news clips, 1991

    Science.gov (United States)

    1991-08-01

    Published stories are presented that sample a year's news coverage of Antarctica. The intent is to provide the U.S. Antarctic Program participants with a digest of current issues as presented by a variety of writers and popular publications. The subject areas covered include the following: earth science; ice studies; stratospheric ozone; astrophysics; life science; operations; education; antarctic treaty issues; and tourism

  5. Effect of different temperature regimes on the chlorophyll a concentration in four species of Antarctic macroalgae

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.

    th Symp. on Polar Biology, Nat. Inst. Pf Polar Research. Tokyo. Mem. natn. lnst. polar Res. Tokyo(Spec.Issue).32: l12-116. Papenfuss, G. F. 1964. Catalogue and bibliography of Antarctic and sub- antarctic benthic marine algae. Am. Geophys. Union...

  6. Extracellular proteases from the Antarctic marine Pseudoalteromonas sp. P96-47 strain Proteasas extracelulares de la cepa marina antártica Pseudoalteromonas sp. P96-47

    Directory of Open Access Journals (Sweden)

    S.C. Vázquez

    2008-03-01

    Full Text Available The extracellular protease-production capacity of 33 bacterial isolates taken from marine biotopes in King George Island, Antarctica, was evaluated in liquid cultures. The P96-47 isolate was selected due to its high production capacity and was identified as Pseudoalteromonas sp. The optimal growth temperature was 20 °C and the optimal for protease production was 15 °C. Proteases were purified from culture supernatants, developing a multiple-band profile in zymograms. They were classified as neutral metalloproteases and worked optimally at 45 °C with an Eact of 47 kJ/ mol. Their stability was higher at neutral pH, retaining more than 80% of activity at pH 6-10 after 3 h incubation at 4 °C. After 90 min incubation at 40 and 50 °C, the percentages of residual activities were 78% and 44%. These results contribute to the basic knowledge of Antarctic marine proteases and also help evaluate the probable industrial applications of P96-47 proteases.La capacidad productora de proteasas extracelulares de 33 aislamientos bacterianos tomados de biotopos marinos en la Isla Rey Jorge, Antártida, fue evaluada en cultivo líquido. El aislamiento P96-47 fue seleccionado debido a su alta capacidad productora y fue identificado como Pseudoalteromonas sp. La temperatura óptima de crecimiento fue de 20 °C y la de producción de 15 °C. Las proteasas fueron purificadas a partir del sobrenadante de cultivo, y en los zimogramas desarrollaron un perfil de múltiples bandas. Estas proteasas fueron clasificadas como metaloproteasas neutras y se observó que trabajan óptimamente a 45 °C, con una Eact de 47 kJ/ mol. Su estabilidad fue superior a pH neutro y retuvieron más del 80% de su actividad a pH 6-10 después de 3 h de incubación a 4 °C. Luego de 90 min de incubación a 40 y 50 °C, las actividades residuales fueron 78% y 44%, respectivamente. Los resultados que se presentan en este trabajo contribuyen al conocimiento básico de las proteasas marinas ant

  7. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula 1987-88, SDLS CD-ROM vol 24

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1987-88 in the Antarctic Peninsula, Antarctica, by the Japan National Oil...

  8. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula - 1985, SDLS CD-ROM vol 16

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1985 field season along the north side of the Antarctic-Peninsula by the British...

  9. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula - 1988-1989, SDLS CD-ROM vol 25

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1988-89 in the Antarctic Peninsula, Antarctica, by the Japan National Oil...

  10. 77 FR 19646 - Marine Mammals; File No. 17178

    Science.gov (United States)

    2012-04-02

    ... 1208 Greate Road, Gloucester Point, VA 23062, has applied in due form for a permit to import marine... the dietary preferences and feeding ecology of Antarctic marine mammals by analyzing seal and whale...

  11. Determination of trace metals in samples from the marine environment and the Antarctic as a basis for understanding the atmospheric transport of heavy metals, and analysis of metal traces in ultra-pure copper matrices. Bestimmung von Spurenmetallen in Proben aus der marinen Umgebung und der Antarktis als Grundlage fuer das Verstaendnis des atmosphaerischen Transportes von Schwermetallen und Analyse von Metallspuren in Reinstkupfermatrices

    Energy Technology Data Exchange (ETDEWEB)

    Voelkening, J

    1988-01-01

    With the aid of reference materials (CRM 74 and CRM 75) from the Bureau of Reference of the European Community in Brussels, a mass spectroscopic method with isotope dilution was developed for determining Cr, Ni, Zn, Cd, and Pb (partly to the mg/g-range). The aim was to establish a north-to-south concentration profile for these elements and in addition, Fe, Cu, and Tl in aerosol over the Atlantic. Moreover, aerosol samples were collected in the Antarctic, Antarctic snow was examined for its heavy metal content, and precipitation and seawater were analysed. As a supplementary method of analysis and comparison, differential inversed-pulse voltammetry was employed. As regards extension, the result of this work represents the so far most comprehensive documention on heavy metals in the marine atmosphere. In the middle of the South Atlantic, extremely low contents are found for all elements. These are comparable only with data from the South Pacific (Samoa) or the Antarctic. By calculating enrichment factors, inferences can be drawn for different areas to the sources of the individual elements. Thus, the element Cr stems almost exclusively from airborne mineral dust, while there is found to be a high anthropogenic proportion for instance for the elements Zn, Cd, and Pb, especially near the coasts. (orig./RB).

  12. Tolerance of Antarctic soil fungi to hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Kevin A.; Bridge, Paul; Clark, Melody S. [British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET (United Kingdom)

    2007-01-01

    Little is known about the effects of hydrocarbons and fuel oil on Antarctic filamentous fungi in the terrestrial Antarctic environment. Growth of fungi and bacteria from soils around Rothera Research Station (Adelaide Island, Antarctic Peninsula) was assessed in the presence of ten separate aromatic and aliphatic hydrocarbons [marine gas oil (MGO), dodecane, hexadecane, benzoic acid, p-hydroxybenzoic acid, toluene, phenol, biphenyl, naphthalene and m- and p-xylenes with ethylbenzene]. Aromatic hydrocarbons inhibited soil microbial growth more than aliphatic hydrocarbons. Soil microorganisms from a moss patch, where little previous impact or hydrocarbon contamination had occurred, were less tolerant of hydrocarbons than those from high impact sites. Fungal growth rates of Mollisia sp., Penicillium commune, Mortierella sp., Trichoderma koningii, Trichoderma sp. and Phoma herbarum were assessed in the presence of hydrocarbons. Generally, aromatic hydrocarbons inhibited or stopped hyphal extension, though growth rates increased with some aliphatic hydrocarbons. Hyphal dry weight measurements suggested that Mortierella sp. may be able to use dodecane as sole carbon and energy source. Hydrocarbon-degrading Antarctic fungi may have use in future hydrocarbon spill bioremediation. (author)

  13. Common metabolic constraints on dive duration in endothermic and ectothermic vertebrates

    Directory of Open Access Journals (Sweden)

    April Hayward

    2016-10-01

    Full Text Available Dive duration in air-breathing vertebrates is thought to be constrained by the volume of oxygen stored in the body and the rate at which it is consumed (i.e., “oxygen store/usage hypothesis”. The body mass-dependence of dive duration among endothermic vertebrates is largely supportive of this model, but previous analyses of ectothermic vertebrates show no such body mass-dependence. Here we show that dive duration in both endotherms and ectotherms largely support the oxygen store/usage hypothesis after accounting for the well-established effects of temperature on oxygen consumption rates. Analyses of the body mass and temperature dependence of dive duration in 181 species of endothermic vertebrates and 29 species of ectothermic vertebrates show that dive duration increases as a power law with body mass, and decreases exponentially with increasing temperature. Thus, in the case of ectothermic vertebrates, changes in environmental temperature will likely impact the foraging ecology of divers.

  14. Big biology meets microclimatology: Defining thermal niches of ectotherms at landscape scales for conservation planning

    Science.gov (United States)

    Daniel J. Isaak; Seth J. Wenger; Michael K. Young

    2017-01-01

    Temperature profoundly affects ecology, a fact ever more evident as the ability to measure thermal environments increases and global changes alter these environments. The spatial structure of thermalscapes is especially relevant to the distribution and abundance of ectothermic organisms but the ability to describe biothermal relationships at extents and grains relevant...

  15. Thermal and energetic constraints on ectotherm abundance: A global test using lizards

    Science.gov (United States)

    Buckley, L.B.; Rodda, G.H.; Jetz, W.

    2008-01-01

    Population densities of birds and mammals have been shown to decrease with body mass at approximately the same rate as metabolic rates increase, indicating that energetic needs constrain endotherm population densities. In ectotherms, the exponential increase of metabolic rate with body temperature suggests that environmental temperature may additionally constrain population densities. Here we test simple bioenergetic models for an ecologically important group of ectothermic vertebrates by examining 483 lizard populations. We find that lizard population densities decrease as a power law of body mass with a slope approximately inverse to the slope of the relationship between metabolic rates and body mass. Energy availability should limit population densities. As predicted, environmental productivity has a positive effect on lizard density, strengthening the relationship between lizard density and body mass. In contrast, the effect of environmental temperature is at most weak due to behavioral thermoregulation, thermal evolution, or the temperature dependence of ectotherm performance. Our results provide initial insights into how energy needs and availability differentially constrain ectotherm and endotherm density across broad spatial scales. ?? 2008 by the Ecological Society of America.

  16. Are Chicken Embryos Endotherms or Ectotherms? A Laboratory Exercise Integrating Concepts in Thermoregulation and Metabolism

    Science.gov (United States)

    Hiebert, Sara M; Noveral, Jocelyne

    2007-01-01

    This investigative laboratory exercise uses the different relations between ambient temperature and metabolic rate in endotherms and ectotherms as a core concept to answer the following question: What thermoregulatory mode is employed by chicken embryos? Emphasis is placed on the physiological concepts that can be taught with this exercise,…

  17. Stream isotherm shifts from climate change and implications for distributions of ectothermic organisms

    Science.gov (United States)

    Daniel J. Isaak; Bruce E. Rieman

    2013-01-01

    Stream ecosystems are especially vulnerable to climate warming because most aquatic organisms are ectothermic and live in dendritic networks that are easily fragmented. Many bioclimatic models predict significant range contractions in stream biotas, but subsequent biological assessments have rarely been done to determine the accuracy of these predictions. Assessments...

  18. Airspace: Antarctic Sound Transmission

    OpenAIRE

    Polli, Andrea

    2009-01-01

    This paper investigates how sound transmission can contribute to the public understanding of climate change within the context of the Poles. How have such transmission-based projects developed specifically in the Arctic and Antarctic, and how do these works create alternative pathways in order to help audiences better understand climate change? The author has created the media project Sonic Antarctica from a personal experience of the Antarctic. The work combines soundscape recordings and son...

  19. Spatial Patterns of Long-Term Erosion Rates Beneath the Marine West Antarctic Ice Sheet: Insights into the Physics of Continental Scale Glacial Erosion from a Comparison with the Ice-Velocity Field

    Science.gov (United States)

    Howat, I. M.; Tulaczyk, S.; Mac Gregor, K.; Joughin, I.

    2001-12-01

    As part of the effort to build quantitative models of glacial erosion and sedimentation, it is particularly important to construct scaled relations between erosion, transport, and sedimentation rates and appropriate glaciological variables (e.g., ice velocity). Recent acquisition of bed topography and ice velocity data for the marine West Antarctic Ice Sheet (WAIS)[Joughin et al., 1999; Lythe et al., in press] provides an unprecedented opportunity to investigate continental-scale patterns of glacial erosion and their relationship to the ice velocity field. Utilizing this data, we construct a map of estimated long-term erosion rates beneath the WAIS. In order to calculate long-term erosion rates from the available data, we assume that: (1) the ice sheet has been present for ~5 mill. years, (2) the initial topography beneath the WAIS was that of a typical ( ~200 m.b.s.l.) continental shelf, and (3) the present topography is near local isostatic equilibrium (Airy type). The map of long-term erosion rates constructed in this fashion shows an intriguing pattern of relatively high rates (of the order of 0.1 mm/yr) concentrated beneath modern ice stream tributaries (ice velocity ~100 m/yr), but much lower erosion rates (of the order of 0.01 mm/yr) beneath both the modern fast-moving ice streams ( ~400 m/yr.) and the slow-moving parts of the ice sheet ( ~10 m/yr). This lack of clear correlation between the estimated erosion rates and ice velocity is somewhat unexpected given that both observational and theoretical studies have shown that bedrock erosion rates beneath mountain glaciers can often be calculated by multiplying the basal sliding velocity by a constant (typically of the order of ~10^-4)(Humphrey and Raymond, 1993 and Mac Gregor et al., 2000). We obtain an improved match between estimated erosion rates and bed topography by calculating erosion rates using horizontal gradients within the ice velocity field rather than the magnitude of ice velocity, as consistent

  20. The Antarctic is a region where the largest human- induced ...

    African Journals Online (AJOL)

    induced perturbation of the marine ecosystem in the world has ... and minke whales feed mainly on krill, and they share a similar feeding area near the Antarctic ice edge. In the .... a result of improved analytical techniques). ...... of this functional response, and further field studies ... ASH, C. E. 1962 — The Whaler's Eye.

  1. Transcriptomics and comparative analysis of three antarctic notothenioid fishes.

    Directory of Open Access Journals (Sweden)

    Seung Chul Shin

    Full Text Available For the past 10 to 13 million years, Antarctic notothenioid fish have undergone extraordinary periods of evolution and have adapted to a cold and highly oxygenated Antarctic marine environment. While these species are considered an attractive model with which to study physiology and evolutionary adaptation, they are poorly characterized at the molecular level, and sequence information is lacking. The transcriptomes of the Antarctic fishes Notothenia coriiceps, Chaenocephalus aceratus, and Pleuragramma antarcticum were obtained by 454 FLX Titanium sequencing of a normalized cDNA library. More than 1,900,000 reads were assembled in a total of 71,539 contigs. Overall, 40% of the contigs were annotated based on similarity to known protein or nucleotide sequences, and more than 50% of the predicted transcripts were validated as full-length or putative full-length cDNAs. These three Antarctic fishes shared 663 genes expressed in the brain and 1,557 genes expressed in the liver. In addition, these cold-adapted fish expressed more Ub-conjugated proteins compared to temperate fish; Ub-conjugated proteins are involved in maintaining proteins in their native state in the cold and thermally stable Antarctic environments. Our transcriptome analysis of Antarctic notothenioid fish provides an archive for future studies in molecular mechanisms of fundamental genetic questions, and can be used in evolution studies comparing other fish.

  2. Revision of Eocene Antarctic carpet sharks (Elasmobranchii, Orectolobiformes) from Seymour Island, Antarctic Peninsula.

    Science.gov (United States)

    Engelbrecht, Andrea; Mörs, Thomas; Reguero, Marcelo A; Kriwet, Jürgen

    2017-01-01

    Seymour Island, Antarctic Peninsula, was once called the 'Rosetta Stone' of Southern Hemisphere palaeobiology, because this small island provides the most complete and richly fossiliferous Palaeogene sequence in Antarctica. Among fossil marine vertebrate remains, chondrichthyans seemingly were dominant elements in the Eocene Antarctic fish fauna. The fossiliferous sediments on Seymour Island are from the La Meseta Formation, which was originally divided into seven stratigraphical levels, TELMs 1-7 (acronym for Tertiary Eocene La Meseta) ranging from the upper Ypresian (early Eocene) to the late Priabonian (late Eocene). Bulk sampling of unconsolidated sediments from TELMs 5 and 6, which are Ypresian (early Eocene) and Lutetian (middle Eocene) in age, respectively, yielded very rich and diverse chondrichthyan assemblages including over 40 teeth of carpet sharks representing two new taxa, Notoramphoscyllium woodwardi gen. et sp. nov. and Ceolometlaouia pannucae gen. et sp. nov. Two additional teeth from TELM 5 represent two different taxa that cannot be assigned to any specific taxon and thus are left in open nomenclature. The new material not only increases the diversity of Eocene Antarctic selachian faunas but also allows two previous orectolobiform records to be re-evaluated. Accordingly, Stegostoma cf. faciatum is synonymized with Notoramphoscyllium woodwardi gen. et sp. nov., whereas Pseudoginglymostoma cf. brevicaudatum represents a nomen dubium . The two new taxa, and probably the additional two unidentified taxa, are interpreted as permanent residents, which most likely were endemic to Antarctic waters during the Eocene and adapted to shallow and estuarine environments.

  3. Analyses of developmental rate isomorphy in ectotherms: Introducing the dirichlet regression

    Czech Academy of Sciences Publication Activity Database

    Boukal S., David; Ditrich, Tomáš; Kutcherov, D.; Sroka, Pavel; Dudová, Pavla; Papáček, M.

    2015-01-01

    Roč. 10, č. 6 (2015), e0129341 E-ISSN 1932-6203 R&D Projects: GA ČR GAP505/10/0096 Grant - others:European Fund(CZ) PERG04-GA-2008-239543; GA JU(CZ) 145/2013/P Institutional support: RVO:60077344 Keywords : ectotherms Subject RIV: ED - Physiology Impact factor: 3.057, year: 2015 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0129341

  4. Development of a Regional Glycerol Dialkyl Glycerol Tetraether (GDGT) - Temperature Calibration for Antarctic and sub-Antarctic Lakes

    Science.gov (United States)

    Roberts, S. J.; Foster, L. C.; Pearson, E. J.; Steve, J.; Hodgson, D.; Saunders, K. M.; Verleyen, E.

    2016-12-01

    Temperature calibration models based on the relative abundances of sedimentary glycerol dialkyl glycerol tetraethers (GDGTs) have been used to reconstruct past temperatures in both marine and terrestrial environments, but have not been widely applied in high latitude environments. This is mainly because the performance of GDGT-temperature calibrations at lower temperatures and GDGT provenance in many lacustrine settings remains uncertain. To address these issues, we examined surface sediments from 32 Antarctic, sub-Antarctic and Southern Chilean lakes. First, we quantified GDGT compositions present and then investigated modern-day environmental controls on GDGT composition. GDGTs were found in all 32 lakes studied. Branched GDGTs (brGDGTs) were dominant in 31 lakes and statistical analyses showed that their composition was strongly correlated with mean summer air temperature (MSAT) rather than pH, conductivity or water depth. Second, we developed the first regional brGDGT-temperature calibration for Antarctic and sub-Antarctic lakes based on four brGDGT compounds (GDGT-Ib, GDGT-II, GDGT-III and GDGT-IIIb). Of these, GDGT-IIIb proved particularly important in cold lacustrine environments. Our brGDGT-Antarctic temperature calibration dataset has an improved statistical performance at low temperatures compared to previous global calibrations (r2=0.83, RMSE=1.45°C, RMSEP-LOO=1.68°C, n=36 samples), highlighting the importance of basing palaeotemperature reconstructions on regional GDGT-temperature calibrations, especially if specific compounds lead to improved model performance. Finally, we applied the new Antarctic brGDGT-temperature calibration to two key lake records from the Antarctic Peninsula and South Georgia. In both, downcore temperature reconstructions show similarities to known Holocene warm periods, providing proof of concept for the new Antarctic calibration model.

  5. Climate Change Impacts in the sub-Antarctic Islands Technical Report N.2 of ONERC

    International Nuclear Information System (INIS)

    2009-01-01

    Difficult to apprehend as a whole, the polar regions constitute the Arctic to the North, an ocean surrounded by emerged lands, and the Antarctic to the South, a continent bordered by the Austral Ocean where a belt of sub Antarctic islands lies. Climate change impacts on sub Antarctic islands are varied, direct and indirect: glacier retreat, more favourable conditions for introduced species, marine biodiversity modification, etc. This report discusses the French, British, Australian, South African and New Zealand sub Antarctic islands, the climatic evolutions and the resulting impacts, focused especially on biodiversity. The Observatoire National sur les Effets du Rechauffement Climatique and the International Polar Foundation have been joined in this endeavour by the French polar institute Paul-Emile Victor, the administration of the French Southern and Antarctic Lands (TAAF in French) and the International Union for the Conservation of Nature. (authors)

  6. Unveiling the Antarctic subglacial landscape.

    Science.gov (United States)

    Warner, Roland; Roberts, Jason

    2010-05-01

    Better knowledge of the subglacial landscape of Antarctica is vital to reducing uncertainties regarding prediction of the evolution of the ice sheet. These uncertainties are associated with bedrock geometry for ice sheet dynamics, including possible marine ice sheet instabilities and subglacial hydrological pathways (e.g. Wright et al., 2008). Major collaborative aerogeophysics surveys motivated by the International Polar Year (e.g. ICECAP and AGAP), and continuing large scale radar echo sounding campaigns (ICECAP and NASA Ice Bridge) are significantly improving the coverage. However, the vast size of Antarctica and logistic difficulties mean that data gaps persist, and ice thickness data remains spatially inhomogeneous. The physics governing large scale ice sheet flow enables ice thickness, and hence bedrock topography, to be inferred from knowledge of ice sheet surface topography and considerations of ice sheet mass balance, even in areas with sparse ice thickness measurements (Warner and Budd, 2000). We have developed a robust physically motivated interpolation scheme, based on these methods, and used it to generate a comprehensive map of Antarctic bedrock topography, using along-track ice thickness data assembled for the BEDMAP project (Lythe et al., 2001). This approach reduces ice thickness biases, compared to traditional inverse distance interpolation schemes which ignore the information available from considerations of ice sheet flow. In addition, the use of improved balance fluxes, calculated using a Lagrangian scheme, eliminates the grid orientation biases in ice fluxes associated with finite difference methods (Budd and Warner, 1996, Le Brocq et al., 2006). The present map was generated using a recent surface DEM (Bamber et al., 2009, Griggs and Bamber, 2009) and accumulation distribution (van de Berg et al., 2006). Comparing our results with recent high resolution regional surveys gives confidence that all major subglacial topographic features are

  7. Regional genetic diversity patterns in Antarctic hairgrass (Deschampsia antartica Desv.)

    NARCIS (Netherlands)

    van de Wouw, M.J.; Van Dijk, P.J.; Huiskes, A.H.L.

    2008-01-01

    Aim To determine patterns in diversity of a major Antarctic plant species, including relationships of Antarctic populations with those outside the Antarctic zone. Location Antarctic Peninsula, Maritime Antarctica, sub-Antarctic islands, Falkland Islands and South America. Methods Amplified fragment

  8. Cosmogenic nuclides constrain surface fluctuations of an East Antarctic outlet glacier since the Pliocene.

    OpenAIRE

    Jones, R.S.; Norton, K.P.; Mackintosh, A.N.; Anderson, J.T.H.; Kubik, P.; Vockenhuber, C.; Wittman, H.; Fink, D.; Wilson, G.S.; Golledge, N.R.; McKay, R.

    2017-01-01

    Understanding past changes in the Antarctic ice sheets provides insight into how they might respond to future climate warming. During the Pliocene and Pleistocene, geological data show that the East Antarctic Ice Sheet responded to glacial and interglacial cycles by remaining relatively stable in its interior, but oscillating at its marine-based margin. It is currently not clear how outlet glaciers, which connect the ice sheet interior to its margin, responded to these orbitally-paced climate...

  9. Antarctic aerosols - A review

    Science.gov (United States)

    Shaw, Glenn E.

    1988-02-01

    Tropospheric aerosols with the diameter range of half a micron reside in the atmosphere for tens of days and teleconnect Antarctica with other regions by transport that reaches planetary scales of distances; thus, the aerosol on the Antarctic ice represents 'memory modules' of events that took place at regions separated from Antarctica by tens of thousands of kilometers. In terms of aerosol mass, the aerosol species include insoluble crustal products (less than 5 percent), transported sea-salt residues (highly variable but averaging about 10 percent), Ni-rich meteoric material, and anomalously enriched material with an unknown origin. Most (70-90 percent by mass) of the aerosol over the Antarctic ice shield, however, is the 'natural acid sulfate aerosol', apparently deriving from biological processes taking place in the surrounding oceans.

  10. Short-term forest management effects on a long-lived ectotherm.

    Directory of Open Access Journals (Sweden)

    Andrea F Currylow

    Full Text Available Timber harvesting has been shown to have both positive and negative effects on forest dwelling species. We examined the immediate effects of timber harvests (clearcuts and group selection openings on ectotherm behavior, using the eastern box turtle as a model. We monitored the movement and thermal ecology of 50 adult box turtles using radiotelemetry from May-October for two years prior to, and two years following scheduled timber harvests in the Central Hardwoods Region of the U.S. Annual home ranges (7.45 ha, 100% MCP did not differ in any year or in response to timber harvests, but were 33% larger than previous estimates (range 0.47-187.67 ha. Distance of daily movements decreased post-harvest (from 22 m±1.2 m to 15 m±0.9 m whereas thermal optima increased (from 23±1°C to 25±1°C. Microclimatic conditions varied by habitat type, but monthly average temperatures were warmer in harvested areas by as much as 13°C. Animals that used harvest openings were exposed to extreme monthly average temperatures (∼40°C. As a result, the animals made shorter and more frequent movements in and out of the harvest areas while maintaining 9% higher body temperatures. This experimental design coupled with radiotelemetry and behavioral observation of a wild ectotherm population prior to and in response to anthropogenic habitat alteration is the first of its kind. Our results indicate that even in a relatively contiguous forested landscape with small-scale timber harvests, there are local effects on the thermal ecology of ectotherms. Ultimately, the results of this research can benefit the conservation and management of temperature-dependent species by informing effects of timber management across landscapes amid changing climates.

  11. Antarctic Meteorite Newsletter

    Science.gov (United States)

    Lindstrom, Marilyn

    2000-01-01

    This newsletter contains something for everyone! It lists classifications of about 440 meteorites mostly from the 1997 and 1998 ANSMET (Antarctic Search for Meteorites) seasons. It also gives descriptions of about 45 meteorites of special petrologic type. These include 1 iron, 17 chondrites (7 CC, 1 EC, 9 OC) and 27 achondrites (25 HED, UR). Most notable are an acapoloite (GRA98028) and an olivine diogenite (GRA98108).

  12. Constraints of bioenergetics on the ecology and distribution of vertebrate ectotherms

    Energy Technology Data Exchange (ETDEWEB)

    Spotila, J.R.

    1992-11-01

    The constraints of bioenergetics on the ecology and distribution of vertebrate ectotherms were quantified. During this project we conducted studies: to determine the role of incubation temperature on the post-hatching growth rate of the snapping turtle, Chelydra serpentina; to establish the rate of energy expenditure of the slider turtle, Trachemys scripta, in the field; to determine the field metabolic rates, body temperatures and selected microclimates of the box turtle, Terrapene carolina, and to measure the effect of diet type on the consumption rate, digestion rate and digestive efficiency of adult T. scripta. We also completed our research on the three-dimensional bioenergetic climate space for freshwater turtles.

  13. The late Cainozoic East Antarctic ice sheet

    International Nuclear Information System (INIS)

    Colhoun, E.A.

    1999-01-01

    A review, mainly of East Antarctic late Cainozoic (post 40 Ma) geological and geomorphological evidence, supports the hypothesis of the continuous presence of an ice sheet, of about the present size, since the late Miocene. Evidence is presented and the view advanced that, during the late Wisconsin maximum of isotope stage 2, ice was not nearly as thick or extensive over the continental shelf as required by the model of 'maximum' Antarctic glaciation. Some of the factors influencing the contribution of Antarctica to post-glacial sea-level rise are discussed. It is considered that Antarctica's contribution was probably considerably less than previously estimated. The dating of marine and freshwater sequences in the Vestfold and Bunger Hills is consistent with deglaciation around the Pleistocene Holocene boundary, after the Late Wisconsin maximum. A date of ∼25 ka BP from permafrost in the Larsemann Hills means that either the Larsemann Hills were not glaciated during the Late Wisconsin or the ice failed to erode much of the permafrost surface. The degree of weathering of rock and glacial drifts in the Vestfold, Larsemann and Bunger Hills suggests a long time for formation, perhaps considerably longer than indicated by the dated marine and freshwater sediment sequences. Cosmogenic isotope dating in the Vestfold Hills has provided equivocal ages for deglaciation. While the results could indicate deglaciation before 80 ka BP, they do not confirm such early deglaciation. If the ice cover was thin and failed to remove the previous rock exposure profile, then the assays could predate the last ice advance. Weathered iron crust fragments in the till suggest little erosion. The raised beaches of the oases are Holocene. Assuming they have been produced by post Late Wisconsin isostatic uplift and by the Holocene transgression, calculations show that the Antarctic continental ice sheet could not have been more than ∼500 m thicker in the inner shelf-coastal zone. The

  14. 76 FR 43266 - Marine Mammals; File No. 16472

    Science.gov (United States)

    2011-07-20

    ... importing of marine mammals (50 CFR Part 216). The applicant requests a five-year permit to take Antarctic fur seals (Arctocephalus gazella), southern elephant seals (Mirounga leonina), crabeater seals... juveniles; 600 Antarctic fur seal pups; 50 leopard seal adults and juveniles; 50 southern elephant seal...

  15. Tracking the El Nino events from Antarctic ice core records

    International Nuclear Information System (INIS)

    Keskin, S.S.; Oelmez, I.

    2004-01-01

    Sodium and chlorine measurements were made by instrumental neutron activation analysis (INAA) on stratigraphically dated ice core samples from Byrd Station, Antarctica, for the last three centuries. The time period between 1969 and 1989 showed an enhanced impact on the Antarctic ice sheets from oceans in the form of marine aerosols. A disturbed ocean-atmosphere interface due to El Ni Southern Oscillation (ENSO) events seems to be a candidate for this observation in Antarctica. (author)

  16. Analyses of Developmental Rate Isomorphy in Ectotherms: Introducing the Dirichlet Regression.

    Directory of Open Access Journals (Sweden)

    David S Boukal

    Full Text Available Temperature drives development in insects and other ectotherms because their metabolic rate and growth depends directly on thermal conditions. However, relative durations of successive ontogenetic stages often remain nearly constant across a substantial range of temperatures. This pattern, termed 'developmental rate isomorphy' (DRI in insects, appears to be widespread and reported departures from DRI are generally very small. We show that these conclusions may be due to the caveats hidden in the statistical methods currently used to study DRI. Because the DRI concept is inherently based on proportional data, we propose that Dirichlet regression applied to individual-level data is an appropriate statistical method to critically assess DRI. As a case study we analyze data on five aquatic and four terrestrial insect species. We find that results obtained by Dirichlet regression are consistent with DRI violation in at least eight of the studied species, although standard analysis detects significant departure from DRI in only four of them. Moreover, the departures from DRI detected by Dirichlet regression are consistently much larger than previously reported. The proposed framework can also be used to infer whether observed departures from DRI reflect life history adaptations to size- or stage-dependent effects of varying temperature. Our results indicate that the concept of DRI in insects and other ectotherms should be critically re-evaluated and put in a wider context, including the concept of 'equiproportional development' developed for copepods.

  17. Mapping Thermal Habitat of Ectotherms Based on Behavioral Thermoregulation in a Controlled Thermal Environment

    Science.gov (United States)

    Fei, T.; Skidmore, A.; Liu, Y.

    2012-07-01

    Thermal environment is especially important to ectotherm because a lot of physiological functions rely on the body temperature such as thermoregulation. The so-called behavioural thermoregulation function made use of the heterogeneity of the thermal properties within an individual's habitat to sustain the animal's physiological processes. This function links the spatial utilization and distribution of individual ectotherm with the thermal properties of habitat (thermal habitat). In this study we modelled the relationship between the two by a spatial explicit model that simulates the movements of a lizard in a controlled environment. The model incorporates a lizard's transient body temperatures with a cellular automaton algorithm as a way to link the physiology knowledge of the animal with the spatial utilization of its microhabitat. On a larger spatial scale, 'thermal roughness' of the habitat was defined and used to predict the habitat occupancy of the target species. The results showed the habitat occupancy can be modelled by the cellular automaton based algorithm at a smaller scale, and can be modelled by the thermal roughness index at a larger scale.

  18. Revisiting Antarctic Ozone Depletion

    Science.gov (United States)

    Grooß, Jens-Uwe; Tritscher, Ines; Müller, Rolf

    2015-04-01

    Antarctic ozone depletion is known for almost three decades and it has been well settled that it is caused by chlorine catalysed ozone depletion inside the polar vortex. However, there are still some details, which need to be clarified. In particular, there is a current debate on the relative importance of liquid aerosol and crystalline NAT and ice particles for chlorine activation. Particles have a threefold impact on polar chlorine chemistry, temporary removal of HNO3 from the gas-phase (uptake), permanent removal of HNO3 from the atmosphere (denitrification), and chlorine activation through heterogeneous reactions. We have performed simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) employing a recently developed algorithm for saturation-dependent NAT nucleation for the Antarctic winters 2011 and 2012. The simulation results are compared with different satellite observations. With the help of these simulations, we investigate the role of the different processes responsible for chlorine activation and ozone depletion. Especially the sensitivity with respect to the particle type has been investigated. If temperatures are artificially forced to only allow cold binary liquid aerosol, the simulation still shows significant chlorine activation and ozone depletion. The results of the 3-D Chemical Transport Model CLaMS simulations differ from purely Lagrangian longtime trajectory box model simulations which indicates the importance of mixing processes.

  19. Ecuadorian antarctic act

    International Nuclear Information System (INIS)

    1998-02-01

    To develop research in this continent involves to take communion with earth where the cold pole of the planet is located, the stormiest sea of the world surround it and where the capricious continental and geographical distribution permits the pass of meteorological violent and continuous systems. The Ecuador, in execution of the acquired commitments like Full Member of the System of the Antarctic Treaty, carried out the VII Expedition to the White Continent with an extensive program of scientific investigation in the field of: Sciences of Life, Sciences of the Earth and Atmospheric Sciences, so much in the environment of the Pacific Southeast, the Drake Pass, Bransfield Strait and the nearby ecosystems antarctic to Point Fort William in the Greenwich Island, site where the Ecuadorian station Pedro Vicente Maldonado is located. The scientific articles, result of the fruitful work of national investigator is consigned in this fourth edition. This publication constitutes our contribution to the world in the knowledge, understanding and handling of the marvelous White Continent from the middle of our planet, Ecuador

  20. Salmonella infections in Antarctic fauna and island populations of wildlife exposed to human activities in coastal areas of Australia.

    Science.gov (United States)

    Iveson, J B; Shellam, G R; Bradshaw, S D; Smith, D W; Mackenzie, J S; Mofflin, R G

    2009-06-01

    Salmonella infections in Antarctic wildlife were first reported in 1970 and in a search for evidence linking isolations with exposure to human activities, a comparison was made of serovars reported from marine fauna in the Antarctic region from 1982-2004 with those from marine mammals in the Northern hemisphere. This revealed that 10 (83%) Salmonella enterica serovars isolated from Antarctic penguins and seals were classifiable in high-frequency (HF) quotients for serovars prevalent in humans and domesticated animals. In Australia, 16 (90%) HF serovars were isolated from marine birds and mammals compared with 12 (86%) HF serovars reported from marine mammals in the Northern hemisphere. In Western Australia, HF serovars from marine species were also recorded in humans, livestock, mussels, effluents and island populations of wildlife in urban coastal areas. Low-frequency S. enterica serovars were rarely detected in humans and not detected in seagulls or marine species. The isolation of S. Enteritidis phage type 4 (PT4), PT8 and PT23 strains from Adélie penguins and a diversity of HF serovars reported from marine fauna in the Antarctic region and coastal areas of Australia, signal the possibility of transient serovars and endemic Salmonella strains recycling back to humans from southern latitudes in marine foodstuffs and feed ingredients.

  1. RADARSAT: The Antarctic Mapping Project

    Science.gov (United States)

    Jezek, Kenneth C.; Lindstrom, E. (Technical Monitor)

    2002-01-01

    The first Antarctic Imaging Campaign (AIC) occurred during the period September 9, 1997 through October 20, 1997. The AIC utilized the unique attributes of the Canadian RADARSAT-1 to acquire the first, high-resolution, synthetic aperture imagery covering the entire Antarctic Continent. Although the primary goal of the mission was the acquisition of image data, the nearly flawless execution of the mission enabled additional collections of exact repeat orbit data. These data, covering an extensive portion of the interior Antarctic, potentially are suitable for interferometric analysis of topography and surface velocity. This document summarizes the Project through completion with delivery of products to the NASA DAACs.

  2. Dating Antarctic ice sheet collapse: Proposing a molecular genetic approach

    Science.gov (United States)

    Strugnell, Jan M.; Pedro, Joel B.; Wilson, Nerida G.

    2018-01-01

    Sea levels at the end of this century are projected to be 0.26-0.98 m higher than today. The upper end of this range, and even higher estimates, cannot be ruled out because of major uncertainties in the dynamic response of polar ice sheets to a warming climate. Here, we propose an ecological genetics approach that can provide insight into the past stability and configuration of the West Antarctic Ice Sheet (WAIS). We propose independent testing of the hypothesis that a trans-Antarctic seaway occurred at the last interglacial. Examination of the genomic signatures of bottom-dwelling marine species using the latest methods can provide an independent window into the integrity of the WAIS more than 100,000 years ago. Periods of connectivity facilitated by trans-Antarctic seaways could be revealed by dating coalescent events recorded in DNA. These methods allow alternative scenarios to be tested against a fit to genomic data. Ideal candidate taxa for this work would need to possess a circumpolar distribution, a benthic habitat, and some level of genetic structure indicated by phylogeographical investigation. The purpose of this perspective piece is to set out an ecological genetics method to help resolve when the West Antarctic Ice Shelf last collapsed.

  3. Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.

    Science.gov (United States)

    Verberk, Wilco C E P; Bilton, David T; Calosi, Piero; Spicer, John I

    2011-08-01

    Aquatic ectotherms face the continuous challenge of capturing sufficient oxygen from their environment as the diffusion rate of oxygen in water is 3 x 10(5) times lower than in air. Despite the recognized importance of oxygen in shaping aquatic communities, consensus on what drives environmental oxygen availability is lacking. Physiologists emphasize oxygen partial pressure, while ecologists emphasize oxygen solubility, traditionally expressing oxygen in terms of concentrations. To resolve the question of whether partial pressure or solubility limits oxygen supply in nature, we return to first principles and derive an index of oxygen supply from Fick's classic first law of diffusion. This oxygen supply index (OSI) incorporates both partial pressure and solubility. Our OSI successfully explains published patterns in body size and species across environmental clines linked to differences in oxygen partial pressure (altitude, organic pollution) or oxygen solubility (temperature and salinity). Moreover, the OSI was more accurately and consistently related to these ecological patterns than other measures of oxygen (oxygen saturation, dissolved oxygen concentration, biochemical oxygen demand concentrations) and similarly outperformed temperature and altitude, which covaried with these environmental clines. Intriguingly, by incorporating gas diffusion rates, it becomes clear that actually more oxygen is available to an organism in warmer habitats where lower oxygen concentrations would suggest the reverse. Under our model, the observed reductions in aerobic performance in warmer habitats do not arise from lower oxygen concentrations, but instead through organismal oxygen demand exceeding supply. This reappraisal of how organismal thermal physiology and oxygen demands together shape aerobic performance in aquatic ectotherms and the new insight of how these components change with temperature have broad implications for predicting the responses of aquatic communities to

  4. Studying the evolutionary significance of thermal adaptation in ectotherms: The diversification of amphibians' energetics.

    Science.gov (United States)

    Nespolo, Roberto F; Figueroa, Julio; Solano-Iguaran, Jaiber J

    2017-08-01

    A fundamental problem in evolutionary biology is the understanding of the factors that promote or constrain adaptive evolution, and assessing the role of natural selection in this process. Here, comparative phylogenetics, that is, using phylogenetic information and traits to infer evolutionary processes has been a major paradigm . In this study, we discuss Ornstein-Uhlenbeck models (OU) in the context of thermal adaptation in ectotherms. We specifically applied this approach to study amphibians's evolution and energy metabolism. It has been hypothesized that amphibians exploit adaptive zones characterized by low energy expenditure, which generate specific predictions in terms of the patterns of diversification in standard metabolic rate (SMR). We complied whole-animal metabolic rates for 122 species of amphibians, and adjusted several models of diversification. According to the adaptive zone hypothesis, we expected: (1) to find "accelerated evolution" in SMR (i.e., diversification above Brownian Motion expectations, BM), (2) that a model assuming evolutionary optima (i.e., an OU model) fits better than a white-noise model and (3) that a model assuming multiple optima (according to the three amphibians's orders) fits better than a model assuming a single optimum. As predicted, we found that the diversification of SMR occurred most of the time, above BM expectations. Also, we found that a model assuming an optimum explained the data in a better way than a white-noise model. However, we did not find evidence that an OU model with multiple optima fits the data better, suggesting a single optimum in SMR for Anura, Caudata and Gymnophiona. These results show how comparative phylogenetics could be applied for testing adaptive hypotheses regarding history and physiological performance in ectotherms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Big biology meets microclimatology: defining thermal niches of ectotherms at landscape scales for conservation planning.

    Science.gov (United States)

    Isaak, Daniel J; Wenger, Seth J; Young, Michael K

    2017-04-01

    Temperature profoundly affects ecology, a fact ever more evident as the ability to measure thermal environments increases and global changes alter these environments. The spatial structure of thermalscapes is especially relevant to the distribution and abundance of ectothermic organisms, but the ability to describe biothermal relationships at extents and grains relevant to conservation planning has been limited by small or sparse data sets. Here, we combine a large occurrence database of >23 000 aquatic species surveys with stream microclimate scenarios supported by an equally large temperature database for a 149 000-km mountain stream network to describe thermal relationships for 14 fish and amphibian species. Species occurrence probabilities peaked across a wide range of temperatures (7.0-18.8°C) but distinct warm- or cold-edge distribution boundaries were apparent for all species and represented environments where populations may be most sensitive to thermal changes. Warm-edge boundary temperatures for a native species of conservation concern were used with geospatial data sets and a habitat occupancy model to highlight subsets of the network where conservation measures could benefit local populations by maintaining cool temperatures. Linking that strategic approach to local estimates of habitat impairment remains a key challenge but is also an opportunity to build relationships and develop synergies between the research, management, and regulatory communities. As with any data mining or species distribution modeling exercise, care is required in analysis and interpretation of results, but the use of large biological data sets with accurate microclimate scenarios can provide valuable information about the thermal ecology of many ectotherms and a spatially explicit way of guiding conservation investments. © 2017 by the Ecological Society of America.

  6. Comparison of Mitochondrial Reactive Oxygen Species Production of Ectothermic and Endothermic Fish Muscle

    Directory of Open Access Journals (Sweden)

    Lilian Wiens

    2017-09-01

    Full Text Available Recently we demonstrated that the capacity of isolated muscle mitochondria to produce reactive oxygen species, measured as H2O2 efflux, is temperature-sensitive in isolated muscle mitochondria of ectothermic fish and the rat, a representative endothermic mammal. However, at physiological temperatures (15° and 37°C for the fish and rat, respectively, the fraction of total mitochondrial electron flux that generated H2O2, the fractional electron leak (FEL, was far lower in the rat than in fish. Those results suggested that the elevated body temperatures associated with endothermy may lead to a compensatory decrease in mitochondrial ROS production relative to respiratory capacity. To test this hypothesis we compare slow twitch (red muscle mitochondria from the endothermic Pacific bluefin tuna (Thunnus orientalis with mitochondria from three ectothermic fishes [rainbow trout (Oncorhynchus mykiss, common carp (Cyprinus carpio, and the lake sturgeon (Acipenser fulvescens] and the rat. At a common assay temperature (25°C rates of mitochondrial respiration and H2O2 efflux were similar in tuna and the other fishes. The thermal sensitivity of fish mitochondria was similar irrespective of ectothermy or endothermy. Comparing tuna to the rat at a common temperature, respiration rates were similar, or lower depending on mitochondrial substrates. FEL was not different across fish species at a common assay temperature (25°C but was markedly higher in fishes than in rat. Overall, endothermy and warming of Pacific Bluefin tuna red muscle may increase the potential for ROS production by muscle mitochondria but the evolution of endothermy in this species is not necessarily associated with a compensatory reduction of ROS production relative to the respiratory capacity of mitochondria.

  7. Antarctic crabs: invasion or endurance?

    Directory of Open Access Journals (Sweden)

    Huw J Griffiths

    Full Text Available Recent scientific interest following the "discovery" of lithodid crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. This "invasion hypothesis" suggests that decapod crabs were driven out of Antarctica 40-15 million years ago and are only now returning as "warm" enough habitats become available. The hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs (Brachyura, and examination of relatively few Recent lithodid samples from the Antarctic slope. In this paper, we examine the existing lithodid fossil record and present the distribution and biogeographic patterns derived from over 16,000 records of Recent Southern Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the Antarctic. Recent records show that 22 species of crabs and lobsters have been reported from the Southern Ocean, with 12 species found south of 60 °S. All are restricted to waters warmer than 0 °C, with their Antarctic distribution limited to the areas of seafloor dominated by Circumpolar Deep Water (CDW. Currently, CDW extends further and shallower onto the West Antarctic shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West Antarctic shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to Antarctic slope. We conclude there is no evidence for a modern-day "crab invasion". We recommend a repeated targeted lithodid sampling program along the West Antarctic shelf to fully test the validity of the

  8. 76 FR 52354 - Notice of Permit Application Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2011-08-22

    ... can be broken and release plastic into the ocean. (2) Fishing nets: (a) Plankton nets come in a... in ASPA 149-Cape Shirreff, Livingston Island by the Antarctic Marine Living Resources (AMLR) Program... release of a designated pollutant in Antarctica, and for the release of waste in Antarctica. NSF has...

  9. Evolution and Function of the Insulin and Insulin-like Signaling Network in Ectothermic Reptiles: Some Answers and More Questions.

    Science.gov (United States)

    Schwartz, Tonia S; Bronikowski, Anne M

    2016-08-01

    The insulin and insulin-like signaling (IIS) molecular network regulates cellular growth and division, and influences organismal metabolism, growth and development, reproduction, and lifespan. As a group, reptiles have incredible diversity in the complex life history traits that have been associated with the IIS network, yet the research on the IIS network in ectothermic reptiles is sparse. Here, we review the IIS network and synthesize what is known about the function and evolution of the IIS network in ectothermic reptiles. The primary hormones of this network-the insulin-like growth factors 1 and 2 (IGFs) likely function in reproduction in ectothermic reptiles, but the precise mechanisms are unclear, and likely range from influencing mating and ovulation to maternal investment in embryonic development. In general, plasma levels of IGF1 increase with food intake in ectothermic reptiles, but the magnitude of the response to food varies across species or populations and the ages of animals. Long-term temperature treatments as well as thermal stress can alter expression of genes within the IIS network. Although relatively little work has been done on IGF2 in ectothermic reptiles, IGF2 is consistently expressed at higher levels than IGF1 in juvenile ectothermic reptiles. Furthermore, in contrast to mammals that have genetic imprinting that silences the maternal IGF2 allele, in reptiles IGF2 is bi-allelically expressed (based on findings in chickens, a snake, and a lizard). Evolutionary analyses indicate some members of the IIS network are rapidly evolving across reptile species, including IGF1, insulin (INS), and their receptors. In particular, IGF1 displays extensive nucleotide variation across lizards and snakes, which suggests that its functional role may vary across this group. In addition, genetic variation across families and populations in the response of the IIS network to environmental conditions illustrates that components of this network may be evolving in

  10. Natural and anthropogenic hydrocarbons in the Antarctic pack ice

    International Nuclear Information System (INIS)

    Nemirovskaya, I.A.; Novigatsky, A.N.

    2004-01-01

    A field experiment was conducted near the Russian Antarctic stations in May, 2001 in the Pridz Bay and coastal part of the Davies Sea to examine the content of dissolved and suspended forms of aliphatic hydrocarbons in melted snow samples, pack ice and ice cores. The site included clean control areas and polluted test areas. A spill was performed by covering the bare ice surface with marine diesel fuel. The different physical characteristics of clean and polluted ice were measured. This included radiation balance, reflected solar radiation, integral albedo radiation, surface temperature, seawater temperature, salinity at depth, and ice salinity. The study showed that accumulation of natural and anthropogenic hydrocarbon took place in the ice-water barrier zone, mostly in suspended form. It was concluded that for oil spills in pack Antarctic ice, the mechanism of filtration due to convection-diffusion plays an important role in the transformation of diesel fuel. 14 refs., 2 tabs., 2 figs

  11. Antarctic climate change and the environment

    Science.gov (United States)

    2009-11-01

    This volume provides a comprehensive, up-to-date account of how the physical and biological : environment of the Antarctic continent and Southern Ocean has changed from Deep Time until : the present day. It also considers how the Antarctic environmen...

  12. Inverse Relationship of Marine Aerosol and Dust in Antarctic Ice with Fine-Grained Sediment in the South Atlantic Ocean: Implications for Sea-Ice Coverage and Wind Strength

    Directory of Open Access Journals (Sweden)

    Sharon L. Kanfoush

    2012-03-01

    Full Text Available This research seeks to test the hypothesis that natural gamma radiation (NGR from Ocean Drilling Program Site 1094, which displays variability over the last glacial-interglacial cycle similar to dust in the Vostok ice core, reflects fine-grained terrigenous sediment delivered by eolian processes. Grain size was measured on 400 samples spanning 0–20 m in a composite core. Accumulation of the <63μ size fraction at Site 1094 and dust in Vostok exhibit a negative correlation, suggesting the fine sediments are not dominantly eolian. However the technique used for grain size measurements cannot distinguish between terrigenous and biogenous materials; therefore it is possible much fine-grained material is diatoms. An inverse correlation between fine sediments and NGR supports this interpretation, and implies terrigenous materials were at times diluted by microfossils from high biological productivity. Fine marine sediments correlate positively with temperature and negatively with marine aerosol Na+ in Vostok. One plausible explanation is extensive sea-ice of cold intervals steepened ocean-continent temperature gradients, intensified winds, and led to increased transport of dust and marine aerosol to Antarctica yet also reduced biological productivity at Site 1094. Such a reduction despite increases in NGR, potentially representing Fe-rich dust influx, would require light limitation or stratification associated with sea-ice.

  13. Report on field research of the Spanish Antarctic Campaign 2014/15: a cooperative international research project with the 56th Japanese Antarctic Research Expedition

    Directory of Open Access Journals (Sweden)

    Sakae Kudoh

    2015-07-01

    Full Text Available A study on the limnological and ecological characteristics of maritime Antarctic lakes on Byers Peninsula, Livingstone Island, South Shetland Islands, West Antarctica, was conducted by the Spanish Antarctic Research Campaign during the 2014/15 season, in cooperation with the research program of the 56th Japanese Antarctic Research Expedition. Limnological surveys of three hillside lakes and three lagoons near beaches were conducted under conditions of heavy snow cover. Soils and biological samples in the catchment areas of the lakes and lagoons were also collected and analyzed. The hillside lakes were covered by thick ice and snow, which maintained winter water conditions in the lakes, such as irreversible stratification, oxygen depletion of bottom water, very weak underwater light conditions, etc., even in mid-January, although swimming zooplankton were abundant. Water samples were also collected in coastal lagoons and streams, an environment in which birds and marine mammals transport materials through the aquatic system.

  14. Regulating Antarctic Tourism and the Precautionary Principle

    NARCIS (Netherlands)

    Bastmeijer, C.J.; Roura, R.

    2004-01-01

    On the basis of an overview of the developments in Antarctic tourism since 1956, this current development note examines the issue of international regulation of Antarctic tourism. After discussing one of the main management issues in respect of Antarctic tourism ¿ the assessment and prevention of

  15. Spatially Extensive Standardized Surveys Reveal Widespread, Multi-Decadal Increase in East Antarctic Adélie Penguin Populations.

    Science.gov (United States)

    Southwell, Colin; Emmerson, Louise; McKinlay, John; Newbery, Kym; Takahashi, Akinori; Kato, Akiko; Barbraud, Christophe; DeLord, Karine; Weimerskirch, Henri

    2015-01-01

    Seabirds are considered to be useful and practical indicators of the state of marine ecosystems because they integrate across changes in the lower trophic levels and the physical environment. Signals from this key group of species can indicate broad scale impacts or response to environmental change. Recent studies of penguin populations, the most commonly abundant Antarctic seabirds in the west Antarctic Peninsula and western Ross Sea, have demonstrated that physical changes in Antarctic marine environments have profound effects on biota at high trophic levels. Large populations of the circumpolar-breeding Adélie penguin occur in East Antarctica, but direct, standardized population data across much of this vast coastline have been more limited than in other Antarctic regions. We combine extensive new population survey data, new population estimation methods, and re-interpreted historical survey data to assess decadal-scale change in East Antarctic Adélie penguin breeding populations. We show that, in contrast to the west Antarctic Peninsula and western Ross Sea where breeding populations have decreased or shown variable trends over the last 30 years, East Antarctic regional populations have almost doubled in abundance since the 1980's and have been increasing since the earliest counts in the 1960's. The population changes are associated with five-year lagged changes in the physical environment, suggesting that the changing environment impacts primarily on the pre-breeding age classes. East Antarctic marine ecosystems have been subject to a number of changes over the last 50 years which may have influenced Adélie penguin population growth, including decadal-scale climate variation, an inferred mid-20th century sea-ice contraction, and early-to-mid 20th century exploitation of fish and whale populations.

  16. Spatially Extensive Standardized Surveys Reveal Widespread, Multi-Decadal Increase in East Antarctic Adélie Penguin Populations.

    Directory of Open Access Journals (Sweden)

    Colin Southwell

    Full Text Available Seabirds are considered to be useful and practical indicators of the state of marine ecosystems because they integrate across changes in the lower trophic levels and the physical environment. Signals from this key group of species can indicate broad scale impacts or response to environmental change. Recent studies of penguin populations, the most commonly abundant Antarctic seabirds in the west Antarctic Peninsula and western Ross Sea, have demonstrated that physical changes in Antarctic marine environments have profound effects on biota at high trophic levels. Large populations of the circumpolar-breeding Adélie penguin occur in East Antarctica, but direct, standardized population data across much of this vast coastline have been more limited than in other Antarctic regions. We combine extensive new population survey data, new population estimation methods, and re-interpreted historical survey data to assess decadal-scale change in East Antarctic Adélie penguin breeding populations. We show that, in contrast to the west Antarctic Peninsula and western Ross Sea where breeding populations have decreased or shown variable trends over the last 30 years, East Antarctic regional populations have almost doubled in abundance since the 1980's and have been increasing since the earliest counts in the 1960's. The population changes are associated with five-year lagged changes in the physical environment, suggesting that the changing environment impacts primarily on the pre-breeding age classes. East Antarctic marine ecosystems have been subject to a number of changes over the last 50 years which may have influenced Adélie penguin population growth, including decadal-scale climate variation, an inferred mid-20th century sea-ice contraction, and early-to-mid 20th century exploitation of fish and whale populations.

  17. Evaluating Potential Tipping Points of Antarctic basins

    Science.gov (United States)

    Durand, G.; Sainan, S.; Pattyn, F.; Jourdain, N.

    2017-12-01

    Antarctica is currently loosing mass and its forthcoming contribution to sea-level rise could substantially increase during the coming centuries. This is essentially due to geometrical constraints, i.e., in regions where grounded ice lies on a bedrock below sea-level sloping down towards the interior of the ice sheet (retrograde slope). For such a configuration the ice sheet is considered potentially unstable, as suggested by theory. However, recent observations on accelerated grounding-line retreat and new insights in modeling Pine Island and Thwaites glaciers give evidence that such self-sustained retreat, called marine ice sheet instability (MISI), has already been on its way. Although West Antarctica appears to be the most vulnerable region for MISI occurrence, similar topographic configurations are also observed in East Antarctica, in the Wilkes Basin in particular. Therefore, evaluating the MISI potential at a pan-Antarctic scale is becoming a priority. Here, using the f.ETISh ice sheet model, an ensemble of simulations of the entire contemporary Antarctic ice sheet has been carried out. In particular, we investigate the debuttressing of ice shelves required to initiate MISI for each coastal region around Antarctica by forcing the model with realistic sub-shelf melt pulses of varying duration and amplitude. We further identify the currently grounded areas where the outlet glaciers could hardly stabilize, the Amundsen Sea Sector being the more prone to large self-sustained retreats. On the contrary, the ability of Cook and Ninnis ice shelves to recover after large perturbations and enough buttress upstream outlet glaciers tends to limit self-sustained retreat of the sector. For each basin, rates of contribution to sea-level rise are discussed together with the RCPs and time when tipping points could be reached and MISI triggered.

  18. Absorption of ultraviolet radiation by antarctic phytoplankton

    Energy Technology Data Exchange (ETDEWEB)

    Vernet, M.; Mitchell, B.G. (Univ. of California-San Diego, La Jolla (United States))

    1990-01-09

    Antarctic phytoplankton contain UV-absorbing compounds that may block damaging radiation. Compounds that absorb from 320-340 nm were observed in spectral absorption of both particulates and in methanol extracts of the particulates. The decrease in the total concentration of these UV compounds with respect to chlorophyll a, as measured by the ratio of in vitro absorption at 335 nm to absorption at 665 nm is variable and decreases with depth. We observed up to 5-fold decrease in this ratio for samples within the physically mixes surface layer. The absorption of UV radiation in methanol extracts, which peaks from 320 to 340 nm, may be composed of several compounds. Shifts in peak absorption with depth (for example, from 331 nm at surface to 321 nm at 75 m), may be interpreted as a change in composition. Ratios of protective yellow xanthophylls (diadinoxanthin + diatoxanthin) to photosynthetic fucoxanthin-like pigments have highest values in surface waters. As these pigments also absorb in the near UV, their function might extend to protection as well as utilization of UV radiation for photosynthesis. We document strong absorption in the UV from 320-330 nm for Antarctic marine particulates. Below this region of the solar energy spectrum, absolute energy levels of incident radiation drop off dramatically. Only wavelengths shorter than about 320 nm will be significantly enhanced due to ozone depletion. If the absorption we observed serves a protective role for phytoplankton photosynthesis, it appears the peak band is in the region where solar energy increases rapidly, and not in the region where depletion would cause significant variations in absolute flux.

  19. Activity of Antarctic fungi extracts against phytopathogenic bacteria.

    Science.gov (United States)

    Purić, J; Vieira, G; Cavalca, L B; Sette, L D; Ferreira, H; Vieira, M L C; Sass, D C

    2018-06-01

    This study aims to obtain secondary metabolites extracts from filamentous fungi isolated from soil and marine sediments from Antarctic ecosystems and to assess its potential antibacterial activity on Xanthomonas euvesicatoria and Xanthomonas axonopodis pv. passiflorae (phytopathogenic bacteria causing diseases in pepper and tomato and passionfruit, respectively). Among the 66 crude intracellular and extracellular extracts obtained from fungi recovered from soil and 79 obtained from marine sediment samples, 25 showed the ability to prevent the growth of X. euvesicatoria in vitro and 28 showed the ability to prevent the growth of X. axonopodis pv. passiflorae in vitro. Intracellular and extracellular extracts from soil fungi inhibited around 97% of X. euvesicatoria and 98% of X. axonopodis pv. passiflorae at 2·1 mg ml -1 . The average inhibition rates against X. euvesicatoria and X. axonopodis pv. passiflorae for intracellular and extracellular extracts from marine sediments fungi were around 96 and 97%, respectively, at 3·0 mg ml -1 . Extracts containing secondary metabolites with antimicrobial activity against X. euvesicatoria and X. axonopodis pv. passiflorae were obtained, containing possible substitutes for the products currently used to control these phytopathogens. Micro-organisms from extreme ecosystems, such as the Antarctic ecosystem, need to survive in harsh conditions with low temperatures, low nutrients and high UV radiation. Micro-organisms adapt to these conditions evolving diverse biochemical and physiological adaptations essential for survival. All this makes these micro-organisms a rich source of novel natural products based on unique chemical scaffolds. Discovering novel bioactive compounds is essential because of the rise in antibiotic-resistant micro-organisms and the emergence of new infections. Fungi from Antarctic environments have been proven to produce bioactive secondary metabolites against various micro-organisms, but few studies

  20. Modelling the Antarctic Ice Sheet

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Holm, A.

    2015-01-01

    to sea level high stands during past interglacial periods. A number of AIS models have been developed and applied to try to understand the workings of the AIS and to form a robust basis for future projections of the AIS contribution to sea level change. The recent DCESS (Danish Center for Earth System......The Antarctic ice sheet is a major player in the Earth’s climate system and is by far the largest depository of fresh water on the planet. Ice stored in the Antarctic ice sheet (AIS) contains enough water to raise sea level by about 58 m, and ice loss from Antarctica contributed significantly...

  1. Constraining the Antarctic contribution to interglacial sea-level rise

    Science.gov (United States)

    Naish, T.; Mckay, R. M.; Barrett, P. J.; Levy, R. H.; Golledge, N. R.; Deconto, R. M.; Horgan, H. J.; Dunbar, G. B.

    2015-12-01

    Observations, models and paleoclimate reconstructions suggest that Antarctica's marine-based ice sheets behave in an unstable manner with episodes of rapid retreat in response to warming climate. Understanding the processes involved in this "marine ice sheet instability" is key for improving estimates of Antarctic ice sheet contribution to future sea-level rise. Another motivating factor is that far-field sea-level reconstructions and ice sheet models imply global mean sea level (GMSL) was up to 20m and 10m higher, respectively, compared with present day, during the interglacials of the warm Pliocene (~4-3Ma) and Late Pleistocene (at ~400ka and 125ka). This was when atmospheric CO2 was between 280 and 400ppm and global average surface temperatures were 1- 3°C warmer, suggesting polar ice sheets are highly sensitive to relatively modest increases in climate forcing. Such magnitudes of GMSL rise not only require near complete melt of the Greenland Ice Sheet and the West Antarctic Ice Sheet, but a substantial retreat of marine-based sectors of East Antarctic Ice Sheet. Recent geological drilling initiatives on the continental margin of Antarctica from both ship- (e.g. IODP; International Ocean Discovery Program) and ice-based (e.g. ANDRILL/Antarctic Geological Drilling) platforms have provided evidence supporting retreat of marine-based ice. However, without direct access through the ice sheet to archives preserved within sub-glacial sedimentary basins, the volume and extent of ice sheet retreat during past interglacials cannot be directly constrained. Sediment cores have been successfully recovered from beneath ice shelves by the ANDRILL Program and ice streams by the WISSARD (Whillans Ice Stream Sub-glacial Access Research Drilling) Project. Together with the potential of the new RAID (Rapid Access Ice Drill) initiative, these demonstrate the technological feasibility of accessing the subglacial bed and deeper sedimentary archives. In this talk I will outline the

  2. The promise and perils of Antarctic fishes: The remarkable life forms of the Southern Ocean have much to teach science about survival, but human activity is threatening their existence

    OpenAIRE

    O'Brien, Kristin M; Crockett, Elizabeth L

    2012-01-01

    The waters around the Antarctic are a treasure trove of fauna specially adapted to extreme cold temperatures. However, as with many other marine ecosystems, its life forms are threatened by human actions.

  3. ADMAP-2: The second generation Antarctic crustal magnetic anomaly map.

    Science.gov (United States)

    Ferraccioli, F.; Golynsky, A.; Golynsky, D.; Young, D. A.; Eagles, G.; Damaske, D.; Finn, C.; Aitken, A.; von Frese, R. R. B.; Ghidella, M. E.; Kim, H. R.; Hong, J.

    2017-12-01

    ADMAP-2 is the second generation crustal magnetic anomaly compilation for the Antarctic region south of 60°S. It was produced from more than 3.5 million line-km of near-surface terrestrial, airborne and marine magnetic observations collected since the International Geophysical Year 1957/58 through 2013. The data were edited, IGRF corrected, profile levelled and gridded at a 1.5-km interval on a polar stereographic projection using the minimum curvature technique. Given the ubiquitous polar cover of snow, ice and sea water, the magnetic anomaly compilation offers important constraints on the global tectonic processes and crustal properties of the Antarctic. It also links widely separated areas of outcrop to help unify disparate geologic studies, and provides insights on the lithospheric transition between Antarctica and adjacent oceans, as well as the geodynamic evolution of the Antarctic lithosphere in the assembly and break-up of the Gondwana, Rodinia, and Columbia supercontinents and key piercing points for reconstructing linkages between the protocontinents. The magnetic data together with ice-probing radar and gravity information greatly facilitate understanding the evolution of fundamental large-scale geological processes such as continental rifting, intraplate mountain building, subduction and terrane accretion processes, and intraplate basin formation.

  4. Antarctic snow and global climate

    International Nuclear Information System (INIS)

    Granberg, H.B.

    2001-01-01

    Global circulation models (GCM) indicate that global warming will be most pronounced at polar regions and high latitudes, causing concern about the stability of the Antarctic ice cap. A project entitled the Seasonal Snow in Antarctica examined the properties of the near surface snow to determine the current conditions that influence snow cover development. The goal was to assess the response of the snow cover in Queen Maud Land (QML) to an increased atmospheric carbon dioxide content. The Antarctic snow cover in QML was examined as part of the FINNARP expeditions in 1999 and 2000 which examined the processes that influence the snow cover. Its energy and mass balance were also assessed by examining the near surface snow strata in shallow (1-2 m) pits and by taking measurements of environmental variables. This made it possible to determine if the glacier is in danger of melting at this northerly location in the Antarctic. The study also made it possible to determine which variables need to change and by how much, for significant melting to occur. It was shown that the Antarctic anticyclone creates particular conditions that protect the snow cover from melting. The anticyclone brings dry air from the stratosphere during most of the year and is exempt from the water vapour feedback. It was concluded that even a doubling of atmospheric carbon dioxide will not produce major snow melt runoff. 8 refs

  5. Additive impacts of experimental climate change increase risk to an ectotherm at the Arctic's edge

    Science.gov (United States)

    Davenport, Jon M.; Hossack, Blake R.; Fishback, LeeAnn

    2017-01-01

    Globally, Arctic and Subarctic regions have experienced the greatest temperature increases during the last 30 years. These extreme changes have amplified threats to the freshwater ecosystems that dominate the landscape in many areas by altering water budgets. Several studies in temperate environments have examined the adaptive capacity of organisms to enhance our understanding of the potential repercussions of warming and associated accelerated drying for freshwater ecosystems. However, few experiments have examined these impacts in Arctic or Subarctic freshwater ecosystems, where the climate is changing most rapidly. To evaluate the capacity of a widespread ectotherm to anticipated environmental changes, we conducted a mesocosm experiment with wood frogs (Rana sylvatica) in the Canadian Subarctic. Three warming treatments were fully crossed with three drying treatments to simulate a range of predicted changes in wetland environments. We predicted wetland warming and drying would act synergistically, with water temperature partially compensating for some of the negative effects of accelerated drying. Across all drying regimes, a 1 °C increase in water temperature increased the odds of survival by 1.79, and tadpoles in 52-day and 64-day hydroperiod mesocosms were 4.1–4.3 times more likely to survive to metamorphosis than tadpoles in 45-day mesocosms. For individuals who survived to metamorphosis, there was only a weak negative effect of temperature on size. As expected, increased temperatures accelerated tadpole growth through day 30 of the experiment. Our results reveal that one of the dominant herbivores in Subarctic wetlands, wood frog tadpoles, are capable of increasing their developmental rates in response to increased temperature and accelerated drying, but only in an additive manner. The strong negative effects of drying on survival, combined with lack of compensation between these two environmental drivers, suggest changes in the aquatic environment

  6. Seasonal variations in ectotherm growth rates: Quantifying growth as an intermittent non steady state compensatory process

    Science.gov (United States)

    Guarini, J.-M.; Chauvaud, Laurent; Cloern, J.E.; Clavier, J.; Coston-Guarini, J.; Patry, Y.

    2011-01-01

    Generally, growth rates of living organisms are considered to be at steady state, varying only under environmental forcing factors. For example, these rates may be described as a function of light for plants or organic food resources for animals and these could be regulated (or not) by temperature or other conditions. But, what are the consequences for an individual's growth (and also for the population growth) if growth rate variations are themselves dynamic and not steady state? For organisms presenting phases of dormancy or long periods of stress, this is a crucial question. A dynamic perspective for quantifying short-term growth was explored using the daily growth record of the scallop Pecten maximus (L.). This species is a good biological model for ectotherm growth because the shell records growth striae daily. Independently, a generic mathematical function representing the dynamics of mean daily growth rate (MDGR) was implemented to simulate a diverse set of growth patterns. Once the function was calibrated with the striae patterns, the growth rate dynamics appeared as a forced damped oscillation during the growth period having a basic periodicity during two transitory phases (mean duration 43. days) and appearing at both growth start and growth end. This phase is most likely due to the internal dynamics of energy transfer within the organism rather than to external forcing factors. After growth restart, the transitory regime represents successive phases of over-growth and regulation. This pattern corresponds to a typical representation of compensatory growth, which from an evolutionary perspective can be interpreted as an adaptive strategy to coping with a fluctuating environment. ?? 2011 Elsevier B.V.

  7. Additive impacts of experimental climate change increase risk to an ectotherm at the Arctic's edge.

    Science.gov (United States)

    Davenport, Jon M; Hossack, Blake R; Fishback, LeeAnn

    2017-06-01

    Globally, Arctic and Subarctic regions have experienced the greatest temperature increases during the last 30 years. These extreme changes have amplified threats to the freshwater ecosystems that dominate the landscape in many areas by altering water budgets. Several studies in temperate environments have examined the adaptive capacity of organisms to enhance our understanding of the potential repercussions of warming and associated accelerated drying for freshwater ecosystems. However, few experiments have examined these impacts in Arctic or Subarctic freshwater ecosystems, where the climate is changing most rapidly. To evaluate the capacity of a widespread ectotherm to anticipated environmental changes, we conducted a mesocosm experiment with wood frogs (Rana sylvatica) in the Canadian Subarctic. Three warming treatments were fully crossed with three drying treatments to simulate a range of predicted changes in wetland environments. We predicted wetland warming and drying would act synergistically, with water temperature partially compensating for some of the negative effects of accelerated drying. Across all drying regimes, a 1 °C increase in water temperature increased the odds of survival by 1.79, and tadpoles in 52-day and 64-day hydroperiod mesocosms were 4.1-4.3 times more likely to survive to metamorphosis than tadpoles in 45-day mesocosms. For individuals who survived to metamorphosis, there was only a weak negative effect of temperature on size. As expected, increased temperatures accelerated tadpole growth through day 30 of the experiment. Our results reveal that one of the dominant herbivores in Subarctic wetlands, wood frog tadpoles, are capable of increasing their developmental rates in response to increased temperature and accelerated drying, but only in an additive manner. The strong negative effects of drying on survival, combined with lack of compensation between these two environmental drivers, suggest changes in the aquatic environment that

  8. ADMAP-2: The next-generation Antarctic magnetic anomaly map

    Science.gov (United States)

    Golynsky, Alexander; Golynsky, Dmitry; Ferraccioli, Fausto; Jordan, Tom; Damaske, Detlef; Blankenship, Don; Holt, Jack; Young, Duncan; Ivanov, Sergey; Kiselev, Alexander; Jokat, Wilfried; Gohl, Karsten; Eagles, Graeme; Bell, Robin; Armadillo, Egidio; Bozzo, Emanuelle; Caneva, Giorgio; Finn, Carol; Forsberg, Rene; Aitken, Alan

    2017-04-01

    The Antarctic Digital Magnetic Anomaly Project compiled the first international magnetic anomaly map of the Antarctic region south of 60°S (ADMAP-1) some six years after its 1995 launch (Golynsky et al., 2001; Golynsky et al., 2007; von Frese et al., 2007). This magnetic anomaly compilation provided new insights into the structure and evolution of Antarctica, including its Proterozoic-Archaean cratons, Proterozoic-Palaeozoic orogens, Palaeozoic-Cenozoic magmatic arc systems, continental rift systems and rifted margins, large igneous provinces and the surrounding oceanic gateways. The international working group produced the ADMAP-1 database from more than 1.5 million line-kilometres of terrestrial, airborne, marine and satellite magnetic observations collected during the IGY 1957-58 through 1999. Since the publication of the first magnetic anomaly map, the international geomagnetic community has acquired more than 1.9 million line-km of new airborne and marine data. This implies that the amount of magnetic anomaly data over the Antarctic continent has more than doubled. These new data provide important constraints on the geology of the enigmatic Gamburtsev Subglacial Mountains and Prince Charles Mountains, Wilkes Land, Dronning Maud Land, and other largely unexplored Antarctic areas (Ferraccioli et al., 2011, Aitken et al., 2014¸ Mieth & Jokat, 2014, Golynsky et al., 2013). The processing of the recently acquired data involved quality assessments by careful statistical analysis of the crossover errors. All magnetic data used in the ADMAP-2 compilation were delivered as profiles, although several of them were in raw form. Some datasets were decimated or upward continued to altitudes of 4 km or higher with the higher frequency geological signals smoothed out. The line data used for the ADMAP-1 compilation were reprocessed for obvious errors and residual corrugations. The new near-surface magnetic data were corrected for the international geomagnetic reference field

  9. Sea surface temperature contributes to marine crocodylomorph evolution.

    Science.gov (United States)

    Martin, Jeremy E; Amiot, Romain; Lécuyer, Christophe; Benton, Michael J

    2014-08-18

    During the Mesozoic and Cenozoic, four distinct crocodylomorph lineages colonized the marine environment. They were conspicuously absent from high latitudes, which in the Mesozoic were occupied by warm-blooded ichthyosaurs and plesiosaurs. Despite a relatively well-constrained stratigraphic distribution, the varying diversities of marine crocodylomorphs are poorly understood, because their extinctions neither coincided with any major biological crises nor with the advent of potential competitors. Here we test the potential link between their evolutionary history in terms of taxic diversity and two abiotic factors, sea level variations and sea surface temperatures (SST). Excluding Metriorhynchoidea, which may have had a peculiar ecology, significant correlations obtained between generic diversity and estimated Tethyan SST suggest that water temperature was a driver of marine crocodylomorph diversity. Being most probably ectothermic reptiles, these lineages colonized the marine realm and diversified during warm periods, then declined or became extinct during cold intervals.

  10. Evidence of microbial rhodopsins in Antarctic Dry Valley edaphic systems.

    Science.gov (United States)

    Guerrero, Leandro D; Vikram, Surendra; Makhalanyane, Thulani P; Cowan, Don A

    2017-09-01

    Microorganisms able to synthesize rhodopsins have the capacity to translocate ions through their membranes, using solar energy to generate a proton motive force. Rhodopsins are the most abundant phototrophic proteins in oceanic surface waters and are key constituents in marine bacterial ecology. However, it remains unclear how rhodopsins are used in most microorganisms. Despite their abundance in marine and fresh-water systems, the presence of functional rhodopsin systems in edaphic habitats has never been reported. Here, we show the presence of several new putative H + , Na + and Cl + pumping rhodopsins identified by metagenomic analysis of Antarctic desert hypolithic communities. Reconstruction of two Proteobacteria genomes harboring xanthorhodopsin-like proteins and one Bacteroidetes genome with a Na-pumping-like rhodopsin indicated that these bacteria were aerobic heterotrophs possessing the apparent capacity for the functional expression of rhodopsins. The existence of these protein systems in hypolithic bacteria expands the known role of rhodopsins to include terrestrial environments and suggests a possible predominant function as heterotrophic energy supply proteins, a feasible microbial adaptation to the harsh conditions prevalent in Antarctic edaphic systems. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Constraints of bioenergetics on the ecology and distribution of vertebrate ectotherms. Final report, 1 September 1988--30 June 1990

    Energy Technology Data Exchange (ETDEWEB)

    Spotila, J.R.

    1992-11-01

    The constraints of bioenergetics on the ecology and distribution of vertebrate ectotherms were quantified. During this project we conducted studies: to determine the role of incubation temperature on the post-hatching growth rate of the snapping turtle, Chelydra serpentina; to establish the rate of energy expenditure of the slider turtle, Trachemys scripta, in the field; to determine the field metabolic rates, body temperatures and selected microclimates of the box turtle, Terrapene carolina, and to measure the effect of diet type on the consumption rate, digestion rate and digestive efficiency of adult T. scripta. We also completed our research on the three-dimensional bioenergetic climate space for freshwater turtles.

  12. The evolution of body size under environmental gradients in ectotherms: why should Bergmann's rule apply to lizards?

    Directory of Open Access Journals (Sweden)

    Tregenza Tom

    2008-02-01

    Full Text Available Abstract Background The impact of environmental gradients on the evolution of life history traits is a central issue in macroecology and evolutionary biology. A number of hypotheses have been formulated to explain factors shaping patterns of variation in animal mass. One such example is Bergmann's rule, which predicts that body size will be positively correlated with latitude and elevation, and hence, with decreasing environmental temperatures. A generally accepted explanation for this phenotypic response is that as body mass increases, body surface area gets proportionally smaller, which contributes to reduced rates of heat-loss. Phylogenetic and non-phylogenetic evidence reveals that endotherms follow Bergmann's rule. In contrast, while previous non-phylogenetic studies supported this prediction in up to 75% of ectotherms, recent phylogenetic comparative analyses suggest that its validity for these organisms is controversial and less understood. Moreover, little attention has been paid to why some ectotherms conform to this rule, while others do not. Here, we investigate Bergmann's rule in the six main clades forming the Liolaemus genus, one of the largest and most environmentally diverse genera of terrestrial vertebrates. A recent study conducted on some species belonging to four of these six clades concluded that Liolaemus species follow Bergmann's rule, representing the only known phylogenetic support for this model in lizards. However, a later reassessment of this evidence, performed on one of the four analysed clades, produced contrasting conclusions. Results Our results fail to support Bergmann's rule in Liolaemus lizards. Non-phylogenetic and phylogenetic analyses showed that none of the studied clades experience increasing body size with increasing latitude and elevation. Conclusion Most physiological and behavioural processes in ectotherms depend directly upon their body temperature. In cold environments, adaptations to gain heat

  13. The safety band of Antarctic ice shelves

    Science.gov (United States)

    Fürst, Johannes Jakob; Durand, Gaël; Gillet-Chaulet, Fabien; Tavard, Laure; Rankl, Melanie; Braun, Matthias; Gagliardini, Olivier

    2016-05-01

    The floating ice shelves along the seaboard of the Antarctic ice sheet restrain the outflow of upstream grounded ice. Removal of these ice shelves, as shown by past ice-shelf recession and break-up, accelerates the outflow, which adds to sea-level rise. A key question in predicting future outflow is to quantify the extent of calving that might precondition other dynamic consequences and lead to loss of ice-shelf restraint. Here we delineate frontal areas that we label as `passive shelf ice’ and that can be removed without major dynamic implications, with contrasting results across the continent. The ice shelves in the Amundsen and Bellingshausen seas have limited or almost no `passive’ portion, which implies that further retreat of current ice-shelf fronts will yield important dynamic consequences. This region is particularly vulnerable as ice shelves have been thinning at high rates for two decades and as upstream grounded ice rests on a backward sloping bed, a precondition to marine ice-sheet instability. In contrast to these ice shelves, Larsen C Ice Shelf, in the Weddell Sea, exhibits a large `passive’ frontal area, suggesting that the imminent calving of a vast tabular iceberg will be unlikely to instantly produce much dynamic change.

  14. The ANTOSTRAT legacy: Science collaboration and international transparency in potential marine mineral resource exploitation of Antarctica

    Science.gov (United States)

    Cooper, Alan; Barker, Peter; Barrett, Peter; Behrendt, John; Brancolini, Giuliano; Childs, Jonathan R.; Escutia, Carlota; Jokat, Wilfried; Kristoffersen, Yngve; Leitchenkov, German; Stagg, Howard; Tanahashi, Manabu; Wardell, Nigel; Webb, Peter

    2009-01-01

    The Antarctic Offshore Stratigraphy project (ANTOSTRAT; 1989–2002) was an extremely successful collaboration in international marine geological science that also lifted the perceived “veil of secrecy” from studies of potential exploitation of Antarctic marine mineral resources. The project laid the groundwork for circum-Antarctic seismic, drilling, and rock coring programs designed to decipher Antarctica’s tectonic, stratigraphic, and climate histories. In 2002, ANTOSTRAT evolved into the equally successful and currently active Antarctic Climate Evolution research program. The need for, and evolution of, ANTOSTRAT was based on two simple tenets within SCAR and the Antarctic Treaty: international science collaboration and open access to data. The ANTOSTRAT project may be a helpful analog for other regions of strong international science and geopolitical interests, such as the Arctic. This is the ANTOSTRAT story.

  15. Fuel oil and dispersant toxicity to the Antarctic sea urchin (Sterechinus neumayeri).

    Science.gov (United States)

    Alexander, Frances J; King, Catherine K; Reichelt-Brushett, Amanda J; Harrison, Peter L

    2017-06-01

    The risk of a major marine fuel spill in Antarctic waters is increasing, yet there are currently no standard or suitable response methods under extreme Antarctic conditions. Fuel dispersants may present a possible solution; however, little data exist on the toxicity of dispersants or fuels to Antarctic species, thereby preventing informed management decisions. Larval development toxicity tests using 3 life history stages of the Antarctic sea urchin (Sterechinus neumayeri) were completed to assess the toxicity of physically dispersed, chemically dispersed, and dispersant-only water-accommodated fractions (WAFs) of an intermediate fuel oil (IFO 180, BP) and the chemical dispersant Slickgone NS (Dasic International). Despite much lower total petroleum hydrocarbon concentrations, physically dispersed fuels contained higher proportions of low-to-intermediate weight carbon compounds and were generally at least an order of magnitude more toxic than chemically dispersed fuels. Based on concentrations that caused 50% abnormality (EC50) values, the embryonic unhatched blastula life stage was the least affected by fuels and dispersants, whereas the larval 4-armed pluteus stage was the most sensitive. The present study is the first to investigate the possible implications of the use of fuel dispersants for fuel spill response in Antarctica. The results indicate that the use of a fuel dispersant did not increase the hydrocarbon toxicity of IFO 180 to the early life stages of Antarctic sea urchins, relative to physical dispersal. Environ Toxicol Chem 2017;36:1563-1571. © 2016 SETAC. © 2016 SETAC.

  16. Persistent Organic Pollutants in Biotic and Abiotic Components of Antarctic Pristine Environment

    Science.gov (United States)

    Bhardwaj, Laxmikant; Chauhan, Abhishek; Ranjan, Anuj; Jindal, Tanu

    2018-05-01

    Over the past decades, research in Antarctica has built a new understanding of Antarctica, its past, present and future. Human activities and long-range pollutants are increasing on the Antarctic continent. Research on persistent organic pollutants (POPs) has been carried out internationally by several countries having their permanent research stations to explain the impact of an ever increasing range of POPs in Antarctic ecosystem. POPs have been detected in Antarctica despite its geographical isolation and almost complete absence of human settlements. The presence of POPs in different abiotic (atmosphere, water bodies, sediments, soil, sea ice) and biotic components (mosses, lichens, krill, penguins, skua, etc.) in Antarctica has been studied and documented around for decades and has either been banned or strictly regulated but is still found in the environment. This review focuses on recent research pertaining to sources and occurrence of POPs in Antarctic lake water, soil, sediment, lichen, mosses and other Antarctic marine community. This review also proposes to summarize the current state of research on POPs in Antarctica environment and draw the earliest conclusions on possible significance of POPs in Antarctica based on presently available information from related Antarctic environment.

  17. AGU honored for Antarctic book

    Science.gov (United States)

    AGU has won an honorable mention award at the Fifteenth Annual Awards Program for Excellence in Professional and Scholarly Publishing sponsored by the Association of American Publishers for the book Volcanoes of the Antarctic Plate and Southern Oceans. The book is part of AGU's Antarctic Research Series, an outgrowth of research done during the International Geophysical Year that was begun in 1963 with a grant from the National Science Foundation. The award was presented at the AAP Annual Awards Dinner on February 6 at the Ritz-Carlton Hotel in Washington, D.C. The award consists of a medallion and a plate on which the names of the publisher, title, and authors are engraved.

  18. Antarctic macrobenthic communities: A compilation of circumpolar information

    Directory of Open Access Journals (Sweden)

    Julian Gutt

    2013-02-01

    Full Text Available Comprehensive information on Antarctic macrobenthic community structure has been publicly available since the 1960s. It stems from trawl, dredge, grab, and corer samples as well as from direct and camera observations (Table 1–2. The quality of this information varies considerably; it consists of pure descriptions, figures for presence (absence and abundance of some key taxa or proxies for such parameters, e.g. sea-floor cover. Some data sets even cover a defined and complete proportion of the macrobenthos with further analyses on diversity and zoogeography. As a consequence the acquisition of data from approximately 90 different campaigns assembled here was not standardised. Nevertheless, it was possible to classify this broad variety of known macrobenthic assemblages to the best of expert knowledge (Gutt 2007; Fig. 1. This overview does not replace statistically sound community and diversity analyses. However, it shows from where which kind of information is available and it acts as an example of the feasibility and power of such data collections. The data set provides unique georeferenced biological basic information for the planning of future coordinated research activities, e.g. under the umbrella of the biology program “Antarctic Thresholds - Ecosystem Resilience and Adaptation” (AnT-ERA of the Scientific Committee on Antarctic Research (SCAR and especially for actual conservation issues, e.g. the planning of Marine Protected Areas (MPAs by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR.

  19. IPAB Antarctic Drifting Buoy Data, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The World Climate Research Programme (WCRP) International Programme for Antarctic Buoys (IPAB), through participating research organizations in various countries,...

  20. Cambios en la viabilidad de dos bacterias marinas antárticas expuestas a la radiación solar en la columna de agua: influencia de la mezcla vertical Changes in viability of two Antarctic marine bacteria exposed to solar radiation in the water column: influence of vertical mixing

    Directory of Open Access Journals (Sweden)

    E. A. Hernández

    2007-09-01

    Full Text Available Se estudió el efecto de la radiación ultravioleta (RUV sobre dos cepas bacterianas marinas antárticas (UVps y UVvi en la columna de agua de la caleta Potter (Shetland del Sur, Antártida. Frascos de cuarzo con las cepas en estudio fueron expuestos a la radiación solar en superficie, a 1 m y a 3 m de profundidad. Se realizaron ensayos con exposición directa y con filtros interferenciales que discriminaron la radiación UVA y la UVB. En otros ensayos se simuló una mezcla vertical de 4 m/h. Ambas cepas mostraron una disminución significativa del número de unidades formadoras de colonias, tanto en superficie como a 1 m de profundidad, luego de exponerlas a dosis superficiales de UVB de 8,4 kJ m-2. El estudio con filtros interferenciales mostró una disminución significativa de la viabilidad en ambos tratamientos UV en superficie y a 1 m. La cepa UVps mostró mayor sensibilidad a la UVB que a la UVA. La mezcla vertical amortiguó el daño causado por la UVB cuando la dosis en superficie fue de 4,8 kJ m-2. Este efecto amortiguador no se observó cuando la dosis en superficie fue de 7,7 kJ m-2. Estos resultados muestran que el efecto negativo de la RUV sobre el bacterioplancton sería particularmente importante en el primer metro de profundidad de las aguas costeras antárticas con abundante material particulado en suspensión.The effect of UV radiation on two Antarctic marine bacterial strains (UVps and UVvi was studied in the water column of Potter Cove (South Shetland, Antarctica. Quartz flasks were filled with the bacterial suspensions and exposed to solar radiation at 0 m, 1 m and 3 m depth. Assays using flasks exposed to direct solar radiation and others using flasks covered with/by interferential filters which discriminate between UVA and UVB, were performed. In other assays, a vertical mixing of 4 m/h was simulated. Both strains showed a significant decrease in viability (expressed as colony - forming units when exposed to a surface

  1. Antarctic skuas recognize individual humans.

    Science.gov (United States)

    Lee, Won Young; Han, Yeong-Deok; Lee, Sang-Im; Jablonski, Piotr G; Jung, Jin-Woo; Kim, Jeong-Hoon

    2016-07-01

    Recent findings report that wild animals can recognize individual humans. To explain how the animals distinguish humans, two hypotheses are proposed. The high cognitive abilities hypothesis implies that pre-existing high intelligence enabled animals to acquire such abilities. The pre-exposure to stimuli hypothesis suggests that frequent encounters with humans promote the acquisition of discriminatory abilities in these species. Here, we examine individual human recognition abilities in a wild Antarctic species, the brown skua (Stercorarius antarcticus), which lives away from typical human settlements and was only recently exposed to humans due to activities at Antarctic stations. We found that, as nest visits were repeated, the skua parents responded at further distances and were more likely to attack the nest intruder. Also, we demonstrated that seven out of seven breeding pairs of skuas selectively responded to a human nest intruder with aggression and ignored a neutral human who had not previously approached the nest. The results indicate that Antarctic skuas, a species that typically inhabited in human-free areas, are able to recognize individual humans who disturbed their nests. Our findings generally support the high cognitive abilities hypothesis, but this ability can be acquired during a relatively short period in the life of an individual as a result of interactions between individual birds and humans.

  2. Energy intake functions and energy budgets of ectotherms and endotherms derived from their ontogenetic growth in body mass and timing of sexual maturation.

    Science.gov (United States)

    Werner, Jan; Sfakianakis, Nikolaos; Rendall, Alan D; Griebeler, Eva Maria

    2018-05-07

    Ectothermic and endothermic vertebrates differ not only in their source of body temperature (environment vs. metabolism), but also in growth patterns, in timing of sexual maturation within life, and energy intake functions. Here, we present a mathematical model applicable to ectothermic and endothermic vertebrates. It is designed to test whether differences in the timing of sexual maturation within an animal's life (age at which sexual maturity is reached vs. longevity) together with its ontogenetic gain in body mass (growth curve) can predict the energy intake throughout the animal's life (food intake curve) and can explain differences in energy partitioning (between growth, reproduction, heat production and maintenance, with the latter subsuming any other additional task requiring energy) between ectothermic and endothermic vertebrates. With our model we calculated from the growth curves and ages at which species reached sexual maturity energy intake functions and energy partitioning for five ectothermic and seven endothermic vertebrate species. We show that our model produces energy intake patterns and distributions as observed in ectothermic and endothermic species. Our results comply consistently with some empirical studies that in endothermic species, like birds and mammals, energy is used for heat production instead of growth, and with a hypothesis on the evolution of endothermy in amniotes published by us before. Our model offers an explanation on known differences in absolute energy intake between ectothermic fish and reptiles and endothermic birds and mammals. From a mathematical perspective, the model comes in two equivalent formulations, a differential and an integral one. It is derived from a discrete level approach, and it is shown to be well-posed and to attain a unique solution for (almost) every parameter set. Numerically, the integral formulation of the model is considered as an inverse problem with unknown parameters that are estimated using a

  3. Anthropogenic impacts on marine ecosystems in Antarctica.

    Science.gov (United States)

    Aronson, Richard B; Thatje, Sven; McClintock, James B; Hughes, Kevin A

    2011-03-01

    Antarctica is the most isolated continent on Earth, but it has not escaped the negative impacts of human activity. The unique marine ecosystems of Antarctica and their endemic faunas are affected on local and regional scales by overharvesting, pollution, and the introduction of alien species. Global climate change is also having deleterious impacts: rising sea temperatures and ocean acidification already threaten benthic and pelagic food webs. The Antarctic Treaty System can address local- to regional-scale impacts, but it does not have purview over the global problems that impinge on Antarctica, such as emissions of greenhouse gases. Failure to address human impacts simultaneously at all scales will lead to the degradation of Antarctic marine ecosystems and the homogenization of their composition, structure, and processes with marine ecosystems elsewhere. © 2011 New York Academy of Sciences.

  4. Thermoregulation and temperature relations of alligators and other large ectotherms inhabiting thermally stressed habitats. Annual progress report, 1 July 1976--30 September 1977

    International Nuclear Information System (INIS)

    Spotila, J.R.

    1977-06-01

    Progress is reported on studies of the biophysical and thermal relationships between large ectotherms and their aquatic environment. Data are reported from laboratory and field studies on alligators, turtles, and fish. Mathematical models of the effect of body size and physical characteristics on temperature regulation of ectotherms and of thermal stress in aquatic organisms were developed. Results are included of field studies on the physiological and behavioral adjustments of turtles in response to changes in water temperature produced by thermal effluents in PAR Pond at the Savannah River Ecology Laboratory

  5. Thermal sensitivity of immune function: evidence against a generalist-specialist trade-off among endothermic and ectothermic vertebrates

    Science.gov (United States)

    Butler, Michael W.; Stahlschmidt, Zachary R.; Ardia, Daniel R.; Davies, Scott; Davis, Jon; Guillette, Louis J.; Johnson, Nicholas; McCormick, Stephen D.; McGraw, Kevin J.; DeNardo, Dale F.

    2013-01-01

    Animal body temperature (Tbody) varies over daily and annual cycles, affecting multiple aspects of biological performance in both endothermic and ectothermic animals. Yet a comprehensive comparison of thermal performance among animals varying in Tbody (mean and variance) and heat production is lacking. Thus, we examined the thermal sensitivity of immune function (a crucial fitness determinant) in Vertebrata, a group encompassing species of varying thermal biology. Specifically, we investigated temperature-related variation in two innate immune performance metrics, hemagglutination and hemolysis, for 13 species across all seven major vertebrate clades. Agglutination and lysis were temperature dependent and were more strongly related to the thermal biology of species (e.g., mean Tbody) than to the phylogenetic relatedness of species, although these relationships were complex and frequently surprising (e.g., heterotherms did not exhibit broader thermal performance curves than homeotherms). Agglutination and lysis performance were positively correlated within species, except in taxa that produce squalamine, a steroidal antibiotic that does not lyse red blood cells. Interestingly, we found the antithesis of a generalist-specialist trade-off: species with broader temperature ranges of immune performance also had higher peak performance levels. In sum, we have uncovered thermal sensitivity of immune performance in both endotherms and ectotherms, highlighting the role that temperature and life history play in immune function across Vertebrata.

  6. Draft genome sequence of Bizionia argentinensis, isolated from antarctic surface water

    OpenAIRE

    Lanzarotti, E.; Pellizza, L.; Bercovich, A.; Foti, M.; Coria, S.H.; Vazquez, S.C.; Ruberto, L.; Hernández, E.A.; Dias, R.L.; Mac Cormack, W.P.; Cicero, D.O.; Smal, C.; Nicolas, M.F.; Vasconcelos, A.T.R.; Marti, M.A.

    2011-01-01

    A psychrotolerant marine bacterial strain, designated JUB59 T, was isolated from Antarctic surface seawater and classified as a new species of the genus Bizionia. Here, we present the first draft genome sequence for this genus, which suggests interesting features such as UV resistance, hydrolytic exoenzymes, and nitrogen metabolism. © 2011, American Society for Microbiology. Fil:Pellizza, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Mac Cormac...

  7. Bacterial diversity of autotrophic enriched cultures from remote, glacial Antarctic, Alpine and Andean aerosol, snow and soil samples

    Science.gov (United States)

    González-Toril, E.; Amils, R.; Delmas, R. J.; Petit, J.-R.; Komárek, J.; Elster, J.

    2009-01-01

    Four different communities and one culture of autotrophic microbial assemblages were obtained by incubation of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas), in a minimal mineral (oligotrophic) media. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. Phylogenetic comparison with the currently available rDNA database allowed sequences belonging to Proteobacteria Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla to be identified. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the marine Antarctic soil the poorest (only one). Snow samples from Col du Midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteriaclone). The only microorganism identified in the Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. Most of the identified microorganisms had been detected previously in cold environments, marine sediments soils and rocks. Air current dispersal is the best model to explain the presence of very specific microorganisms, like those identified in this work, in environments very distant and very different from each other.

  8. Extinction and recolonization of maritime Antarctica in the limpet Nacella concinna (Strebel, 1908) during the last glacial cycle: toward a model of Quaternary biogeography in shallow Antarctic invertebrates.

    Science.gov (United States)

    González-Wevar, C A; Saucède, T; Morley, S A; Chown, S L; Poulin, E

    2013-10-01

    Quaternary glaciations in Antarctica drastically modified geographical ranges and population sizes of marine benthic invertebrates and thus affected the amount and distribution of intraspecific genetic variation. Here, we present new genetic information in the Antarctic limpet Nacella concinna, a dominant Antarctic benthic species along shallow ice-free rocky ecosystems. We examined the patterns of genetic diversity and structure in this broadcast spawner along maritime Antarctica and from the peri-Antarctic island of South Georgia. Genetic analyses showed that N. concinna represents a single panmictic unit in maritime Antarctic. Low levels of genetic diversity characterized this population; its median-joining haplotype network revealed a typical star-like topology with a short genealogy and a dominant haplotype broadly distributed. As previously reported with nuclear markers, we detected significant genetic differentiation between South Georgia Island and maritime Antarctica populations. Higher levels of genetic diversity, a more expanded genealogy and the presence of more private haplotypes support the hypothesis of glacial persistence in this peri-Antarctic island. Bayesian Skyline plot and mismatch distribution analyses recognized an older demographic history in South Georgia. Approximate Bayesian computations did not support the persistence of N. concinna along maritime Antarctica during the last glacial period, but indicated the resilience of the species in peri-Antarctic refugia (South Georgia Island). We proposed a model of Quaternary Biogeography for Antarctic marine benthic invertebrates with shallow and narrow bathymetric ranges including (i) extinction of maritime Antarctic populations during glacial periods; (ii) persistence of populations in peri-Antarctic refugia; and (iii) recolonization of maritime Antarctica following the deglaciation process. © 2013 John Wiley & Sons Ltd.

  9. Environmental radioactivity in the antarctic station

    International Nuclear Information System (INIS)

    Gonzalez, S.; Osores, J.; Martinez, J.; Lopez, E.; Jara, R.

    1998-01-01

    Study about environmental radioactivity in the Peruvian antarctic station Machu Pichu they were carried out during the last three periods to the southern summer. The objective of the project it is to evaluate environmental component in order to elaborate a study it base on the levels background radioactivity and artificial in the antarctic region

  10. South African antarctic biological research programme

    CSIR Research Space (South Africa)

    SASCAR

    1981-07-01

    Full Text Available This document provides a description of the past, current and planned South African biological research activities in the sub-Antarctic and Antarctic regions. Future activities will fall under one of the five components of the research programme...

  11. Carbon dioxide emissions of Antarctic tourism

    NARCIS (Netherlands)

    Farreny, R.; Oliver-Solà, J.; Lamers, M.A.J.; Amelung, B.; Gabarrell, X.; Rieradevall, J.; Boada, M.; Benayas, J.

    2011-01-01

    The increase of tourism to the Antarctic continent may entail not only local but also global environmental impacts. These latter impacts, which are mainly caused by transport, have been generally ignored. As a result, there is a lack of data on the global impacts of Antarctic tourism in terms of

  12. Pakistan and Antarctic research - an overview

    International Nuclear Information System (INIS)

    Rizvi, S.H.

    1993-01-01

    The paper describes the significance of Antarctica and the necessity of conducting scientific research for the understanding of the global environment and through various environmental processes operative in Antarctica. The paper presents a review of the Pakistan's activities and research interests in Antarctica focussing on the salient features of the Pakistan's Antarctic Research Programme and objectives. It summarises the significance of Antarctica, Antarctic Research and the interests of the world in Antarctica and international co-operation for Antarctic Research. The paper also highlights the philosophy of Antarctic Science and provides some guidelines for the development of Antarctic Research programmes for Pakistan and for the newcomers in Antarctica particularly for the developing countries. (author)

  13. Testing oils in antarctic soils

    International Nuclear Information System (INIS)

    Leufkens, D.

    2001-01-01

    The resident seals, whales and penguins in Antarctica's Ross Sea region have only environmentally friendly ways of getting around. In contrast, wherever humans go in the Antarctic and whatever they do, be it research, tourism or fishing, they need fuel for their planes, icebreaker ships, land vehicles and generators. Because of this, petroleum hydrocarbons are the most likely source of pollution in the Antarctic. Accidental oil spills often occur near scientific stations, where storage and refuelling of aircraft and vehicles can result in spills. Spills also occur as a consequence of drilling activities. Dr Jackie Aislabie, a microbiologist from the New Zealand government's research company Landcare Research, is leading a program aimed at understanding how oil spills impact on Antarctic soils. The properties of pristine soils were compared with oil-contaminated soil at three locations: Scott Base, Marble Point and in the Wright Valley at Bull Pass. Soils in the Scott Base area are impacted by the establishment and continuous habitation of the base over 40 years, and a hydrocarbon-contaminated site was sampled near a former storage area for drums of mixed oils. Soil sampled from Marble Point was taken from near the old Marble Point camp, which was inhabited from 1957 to about 1963. Oil stains were visible on the soil surface, and are assumed to have been there for more than 30 years. The samples selected for analysis from the Wright Valley came from a spill site near Bull Pass that occurred during seismic bore-hole drilling activities in 1985. The contamination levels ranged from below detection to just over 29,000 μg/g of soil. Descriptions and analyse results are included into a Geographic Information System and associated soils database

  14. Allometries of Maximum Growth Rate versus Body Mass at Maximum Growth Indicate That Non-Avian Dinosaurs Had Growth Rates Typical of Fast Growing Ectothermic Sauropsids

    Science.gov (United States)

    Werner, Jan; Griebeler, Eva Maria

    2014-01-01

    We tested if growth rates of recent taxa are unequivocally separated between endotherms and ectotherms, and compared these to dinosaurian growth rates. We therefore performed linear regression analyses on the log-transformed maximum growth rate against log-transformed body mass at maximum growth for extant altricial birds, precocial birds, eutherians, marsupials, reptiles, fishes and dinosaurs. Regression models of precocial birds (and fishes) strongly differed from Case’s study (1978), which is often used to compare dinosaurian growth rates to those of extant vertebrates. For all taxonomic groups, the slope of 0.75 expected from the Metabolic Theory of Ecology was statistically supported. To compare growth rates between taxonomic groups we therefore used regressions with this fixed slope and group-specific intercepts. On average, maximum growth rates of ectotherms were about 10 (reptiles) to 20 (fishes) times (in comparison to mammals) or even 45 (reptiles) to 100 (fishes) times (in comparison to birds) lower than in endotherms. While on average all taxa were clearly separated from each other, individual growth rates overlapped between several taxa and even between endotherms and ectotherms. Dinosaurs had growth rates intermediate between similar sized/scaled-up reptiles and mammals, but a much lower rate than scaled-up birds. All dinosaurian growth rates were within the range of extant reptiles and mammals, and were lower than those of birds. Under the assumption that growth rate and metabolic rate are indeed linked, our results suggest two alternative interpretations. Compared to other sauropsids, the growth rates of studied dinosaurs clearly indicate that they had an ectothermic rather than an endothermic metabolic rate. Compared to other vertebrate growth rates, the overall high variability in growth rates of extant groups and the high overlap between individual growth rates of endothermic and ectothermic extant species make it impossible to rule out either

  15. Allometries of maximum growth rate versus body mass at maximum growth indicate that non-avian dinosaurs had growth rates typical of fast growing ectothermic sauropsids.

    Science.gov (United States)

    Werner, Jan; Griebeler, Eva Maria

    2014-01-01

    We tested if growth rates of recent taxa are unequivocally separated between endotherms and ectotherms, and compared these to dinosaurian growth rates. We therefore performed linear regression analyses on the log-transformed maximum growth rate against log-transformed body mass at maximum growth for extant altricial birds, precocial birds, eutherians, marsupials, reptiles, fishes and dinosaurs. Regression models of precocial birds (and fishes) strongly differed from Case's study (1978), which is often used to compare dinosaurian growth rates to those of extant vertebrates. For all taxonomic groups, the slope of 0.75 expected from the Metabolic Theory of Ecology was statistically supported. To compare growth rates between taxonomic groups we therefore used regressions with this fixed slope and group-specific intercepts. On average, maximum growth rates of ectotherms were about 10 (reptiles) to 20 (fishes) times (in comparison to mammals) or even 45 (reptiles) to 100 (fishes) times (in comparison to birds) lower than in endotherms. While on average all taxa were clearly separated from each other, individual growth rates overlapped between several taxa and even between endotherms and ectotherms. Dinosaurs had growth rates intermediate between similar sized/scaled-up reptiles and mammals, but a much lower rate than scaled-up birds. All dinosaurian growth rates were within the range of extant reptiles and mammals, and were lower than those of birds. Under the assumption that growth rate and metabolic rate are indeed linked, our results suggest two alternative interpretations. Compared to other sauropsids, the growth rates of studied dinosaurs clearly indicate that they had an ectothermic rather than an endothermic metabolic rate. Compared to other vertebrate growth rates, the overall high variability in growth rates of extant groups and the high overlap between individual growth rates of endothermic and ectothermic extant species make it impossible to rule out either of

  16. Allometries of maximum growth rate versus body mass at maximum growth indicate that non-avian dinosaurs had growth rates typical of fast growing ectothermic sauropsids.

    Directory of Open Access Journals (Sweden)

    Jan Werner

    Full Text Available We tested if growth rates of recent taxa are unequivocally separated between endotherms and ectotherms, and compared these to dinosaurian growth rates. We therefore performed linear regression analyses on the log-transformed maximum growth rate against log-transformed body mass at maximum growth for extant altricial birds, precocial birds, eutherians, marsupials, reptiles, fishes and dinosaurs. Regression models of precocial birds (and fishes strongly differed from Case's study (1978, which is often used to compare dinosaurian growth rates to those of extant vertebrates. For all taxonomic groups, the slope of 0.75 expected from the Metabolic Theory of Ecology was statistically supported. To compare growth rates between taxonomic groups we therefore used regressions with this fixed slope and group-specific intercepts. On average, maximum growth rates of ectotherms were about 10 (reptiles to 20 (fishes times (in comparison to mammals or even 45 (reptiles to 100 (fishes times (in comparison to birds lower than in endotherms. While on average all taxa were clearly separated from each other, individual growth rates overlapped between several taxa and even between endotherms and ectotherms. Dinosaurs had growth rates intermediate between similar sized/scaled-up reptiles and mammals, but a much lower rate than scaled-up birds. All dinosaurian growth rates were within the range of extant reptiles and mammals, and were lower than those of birds. Under the assumption that growth rate and metabolic rate are indeed linked, our results suggest two alternative interpretations. Compared to other sauropsids, the growth rates of studied dinosaurs clearly indicate that they had an ectothermic rather than an endothermic metabolic rate. Compared to other vertebrate growth rates, the overall high variability in growth rates of extant groups and the high overlap between individual growth rates of endothermic and ectothermic extant species make it impossible to rule

  17. Snow surface microbiome on the High Antarctic Plateau (DOME C).

    Science.gov (United States)

    Michaud, Luigi; Lo Giudice, Angelina; Mysara, Mohamed; Monsieurs, Pieter; Raffa, Carmela; Leys, Natalie; Amalfitano, Stefano; Van Houdt, Rob

    2014-01-01

    The cryosphere is an integral part of the global climate system and one of the major habitable ecosystems of Earth's biosphere. These permanently frozen environments harbor diverse, viable and metabolically active microbial populations that represent almost all the major phylogenetic groups. In this study, we investigated the microbial diversity in the surface snow surrounding the Concordia Research Station on the High Antarctic Plateau through a polyphasic approach, including direct prokaryotic quantification by flow cytometry and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH), and phylogenetic identification by 16S RNA gene clone library sequencing and 454 16S amplicon pyrosequencing. Although the microbial abundance was low (<10(3) cells/ml of snowmelt), concordant results were obtained with the different techniques. The microbial community was mainly composed of members of the Alpha-proteobacteria class (e.g. Kiloniellaceae and Rhodobacteraceae), which is one of the most well-represented bacterial groups in marine habitats, Bacteroidetes (e.g. Cryomorphaceae and Flavobacteriaceae) and Cyanobacteria. Based on our results, polar microorganisms could not only be considered as deposited airborne particles, but as an active component of the snowpack ecology of the High Antarctic Plateau.

  18. Snow surface microbiome on the High Antarctic Plateau (DOME C.

    Directory of Open Access Journals (Sweden)

    Luigi Michaud

    Full Text Available The cryosphere is an integral part of the global climate system and one of the major habitable ecosystems of Earth's biosphere. These permanently frozen environments harbor diverse, viable and metabolically active microbial populations that represent almost all the major phylogenetic groups. In this study, we investigated the microbial diversity in the surface snow surrounding the Concordia Research Station on the High Antarctic Plateau through a polyphasic approach, including direct prokaryotic quantification by flow cytometry and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH, and phylogenetic identification by 16S RNA gene clone library sequencing and 454 16S amplicon pyrosequencing. Although the microbial abundance was low (<10(3 cells/ml of snowmelt, concordant results were obtained with the different techniques. The microbial community was mainly composed of members of the Alpha-proteobacteria class (e.g. Kiloniellaceae and Rhodobacteraceae, which is one of the most well-represented bacterial groups in marine habitats, Bacteroidetes (e.g. Cryomorphaceae and Flavobacteriaceae and Cyanobacteria. Based on our results, polar microorganisms could not only be considered as deposited airborne particles, but as an active component of the snowpack ecology of the High Antarctic Plateau.

  19. No evidence of the effect of extreme weather events on annual occurrence of four groups of ectothermic species.

    Directory of Open Access Journals (Sweden)

    Agnieszka H Malinowska

    Full Text Available Weather extremes may have strong effects on biodiversity, as known from theoretical and modelling studies. Predicted negative effects of increased weather variation are found only for a few species, mostly plants and birds in empirical studies. Therefore, we investigated correlations between weather variability and patterns in occupancy, local colonisations and local extinctions (metapopulation metrics across four groups of ectotherms: Odonata, Orthoptera, Lepidoptera, and Reptilia. We analysed data of 134 species on a 1×1 km-grid base, collected in the last 20 years from the Netherlands, combining standardised data and opportunistic data. We applied dynamic site-occupancy models and used the results as input for analyses of (i trends in distribution patterns, (ii the effect of temperature on colonisation and persistence probability, and (iii the effect of years with extreme weather on all the three metapopulation metrics. All groups, except butterflies, showed more positive than negative trends in metapopulation metrics. We did not find evidence that the probability of colonisation or persistence increases with temperature nor that extreme weather events are reflected in higher extinction risks. We could not prove that weather extremes have visible and consistent negative effects on ectothermic species in temperate northern hemisphere. These findings do not confirm the general prediction that increased weather variability imperils biodiversity. We conclude that weather extremes might not be ecologically relevant for the majority of species. Populations might be buffered against weather variation (e.g. by habitat heterogeneity, or other factors might be masking the effects (e.g. availability and quality of habitat. Consequently, we postulate that weather extremes have less, or different, impact in real world metapopulations than theory and models suggest.

  20. Chilean Antarctic Stations on King George Island

    OpenAIRE

    Katsutada Kaminuma

    2000-01-01

    The purpose of my visit to Chilean Antarctic Stations was to assess the present status of geophysical observations and research, as the South Shetland Island, West Antarctica, where the stations are located, are one of the most active tectonic regions on the Antarctic plate. The Instituto Antartico Chileno (INACH) kindly gave me a chance to stay in Frei/Escudero Bases as an exchange scientist under the Antarctic Treaty for two weeks in January 2000. I stayed in Frei Base as a member of a geol...

  1. Antarctic new particle formation from continental biogenic precursors

    Directory of Open Access Journals (Sweden)

    E.-M. Kyrö

    2013-04-01

    Full Text Available Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN. The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

  2. Antarctic new particle formation from continental biogenic precursors

    Science.gov (United States)

    Kyrö, E.-M.; Kerminen, V.-M.; Virkkula, A.; Dal Maso, M.; Parshintsev, J.; Ruíz-Jimenez, J.; Forsström, L.; Manninen, H. E.; Riekkola, M.-L.; Heinonen, P.; Kulmala, M.

    2013-04-01

    Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN). The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher) communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

  3. Brucella antibody seroprevalence in Antarctic seals (Arctocephalus gazella, Leptonychotes weddellii and Mirounga leonina).

    Science.gov (United States)

    Jensen, Silje-Kristin; Nymo, Ingebjørg Helena; Forcada, Jaume; Hall, Ailsa; Godfroid, Jacques

    2013-09-03

    Brucellosis is a worldwide infectious zoonotic disease caused by Gram-negative bacteria of the genus Brucella, and Brucella infections in marine mammals were first reported in 1994. A serosurvey investigating the presence of anti-Brucella antibodies in 3 Antarctic pinniped species was undertaken with a protein A/G indirect enzyme-linked immunosorbent assay (iELISA) and the Rose Bengal test (RBT). Serum samples from 33 Weddell seals Leptonychotes weddelli were analysed, and antibodies were detected in 8 individuals (24.2%) with the iELISA and in 21 (65.6%) with the RBT. We tested 48 southern elephant seal Mirounga leonina sera and detected antibodies in 2 animals (4.7%) with both the iELISA and the RBT. None of the 21 Antarctic fur seals Arctocephalus gazella was found positive. This is the first report of anti-Brucella antibodies in southern elephant seals. The potential impact of Brucella infection in pinnipeds in Antarctica is not known, but Brucella spp. are known to cause abortion in terrestrial species and cetaceans. Our findings suggest that Brucella infection in pinnipeds is present in the Antarctic, but to date B. pinnipedialis has not been isolated from any Antarctic pinniped species, leaving the confirmation of infection pending.

  4. Impact of marine vertebrates on Antarctic terrestrial micro-arthropods

    NARCIS (Netherlands)

    Bokhorst, S.F.; Convey, P.

    2016-01-01

    Traits of primary producers associated with tissue quality are commonly assumed to have strong control over higher trophic levels. However, this view is largely based on studies of vascular plants, and cryptogamic vegetation has received far less attention. In this study natural gradients in

  5. Historical Arctic and Antarctic Surface Observational Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This product consists of meteorological data from 105 Arctic weather stations and 137 Antarctic stations, extracted from the National Climatic Data Center (NCDC)'s...

  6. Abundance, viability and culturability of Antarctic bacteria

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; DeSouza, M.J.B.D.; Nair, S.; Chandramohan, D.

    The viability of total number of bacteria decide the mineralisation rate in any ecosystem and ultimately the fertility of the region. This study aims at establishing the extent of viability in the standing stock of the Antarctic bacterial population...

  7. South African Antarctic earth science research programme

    CSIR Research Space (South Africa)

    SASCAR

    1984-02-01

    Full Text Available This document describes the past, current and planned future South African earth science research programme in the Antarctic, Southern Ocean and subantarctic regions. The scientific programme comprises five components into which present and future...

  8. Productivity and linkages of the food web of the southern region of the western Antarctic Peninsula continental shelf

    Science.gov (United States)

    Ballerini, Tosca; Hofmann, Eileen E.; Ainley, David G.; Daly, Kendra L.; Marrari, Marina; Ribic, Christine A.; Smith, Walker O.; Steele, John H.

    2014-01-01

    The productivity and linkages in the food web of the southern region of the west Antarctic Peninsula continental shelf were investigated using a multi-trophic level mass balance model. Data collected during the Southern Ocean Global Ocean Ecosystem Dynamics field program were combined with data from the literature on the abundance and diet composition of zooplankton, fish, seabirds and marine mammals to calculate energy flows in the food web and to infer the overall food web structure at the annual level. Sensitivity analyses investigated the effects of variability in growth and biomass of Antarctic krill (Euphausia superba) and in the biomass of Antarctic krill predators on the structure and energy fluxes in the food web. Scenario simulations provided insights into the potential responses of the food web to a reduced contribution of large phytoplankton (diatom) production to total primary production, and to reduced consumption of primary production by Antarctic krill and mesozooplankton coincident with increased consumption by microzooplankton and salps. Model-derived estimates of primary production were 187–207 g C m−2 y−1, which are consistent with observed values (47–351 g C m−2 y−1). Simulations showed that Antarctic krill provide the majority of energy needed to sustain seabird and marine mammal production, thereby exerting a bottom-up control on higher trophic level predators. Energy transfer to top predators via mesozooplanton was a less efficient pathway, and salps were a production loss pathway because little of the primary production they consumed was passed to higher trophic levels. Increased predominance of small phytoplankton (nanoflagellates and cryptophytes) reduced the production of Antarctic krill and of its predators, including seabirds and seals.

  9. Productivity and linkages of the food web of the southern region of the western Antarctic Peninsula continental shelf

    Science.gov (United States)

    Ballerini, Tosca; Hofmann, Eileen E.; Ainley, David G.; Daly, Kendra; Marrari, Marina; Ribic, Christine A.; Smith, Walker O.; Steele, John H.

    2014-03-01

    The productivity and linkages in the food web of the southern region of the west Antarctic Peninsula continental shelf were investigated using a multi-trophic level mass balance model. Data collected during the Southern Ocean Global Ocean Ecosystem Dynamics field program were combined with data from the literature on the abundance and diet composition of zooplankton, fish, seabirds and marine mammals to calculate energy flows in the food web and to infer the overall food web structure at the annual level. Sensitivity analyses investigated the effects of variability in growth and biomass of Antarctic krill (Euphausia superba) and in the biomass of Antarctic krill predators on the structure and energy fluxes in the food web. Scenario simulations provided insights into the potential responses of the food web to a reduced contribution of large phytoplankton (diatom) production to total primary production, and to reduced consumption of primary production by Antarctic krill and mesozooplankton coincident with increased consumption by microzooplankton and salps. Model-derived estimates of primary production were 187-207 g C m-2 y-1, which are consistent with observed values (47-351 g C m-2 y-1). Simulations showed that Antarctic krill provide the majority of energy needed to sustain seabird and marine mammal production, thereby exerting a bottom-up control on higher trophic level predators. Energy transfer to top predators via mesozooplanton was a less efficient pathway, and salps were a production loss pathway because little of the primary production they consumed was passed to higher trophic levels. Increased predominance of small phytoplankton (nanoflagellates and cryptophytes) reduced the production of Antarctic krill and of its predators, including seabirds and seals.

  10. Ross Ice Shelf, Antarctic Ice and Clouds

    Science.gov (United States)

    1991-01-01

    In this view of Antarctic ice and clouds, (56.5S, 152.0W), the Ross Ice Shelf of Antarctica is almost totally clear, showing stress cracks in the ice surface caused by wind and tidal drift. Clouds on the eastern edge of the picture are associated with an Antarctic cyclone. Winds stirred up these storms have been known to reach hurricane force.

  11. Understanding and protecting the world's biodiversity: the role and legacy of the SCAR programme "Evolution and Biodiversity in the Antarctic".

    Science.gov (United States)

    di Prisco, Guido; Convey, Peter; Gutt, Julian; Cowan, Don; Conlan, Kathleen; Verde, Cinzia

    2012-12-01

    Current global changes are prompting scientists and governments to consider the risk of extinction of species inhabiting environments influenced by ice. Concerted, multidisciplinary, international programmes aimed at understanding life processes, evolution and adaptations in the Polar Regions will help to counteract such an event by protecting polar life and ecosystems. There is a long tradition of international scientific cooperation in Antarctica that provides a strong foundation for such approaches. While basic understanding is emerging, we still largely lack predictive biological models, and need to achieve further integration amongst biological and non-biological disciplines. The ongoing SCAR Science Research Programme, "Evolution and Biodiversity in the Antarctic (EBA)" has successfully carried out its crucial role of providing an overarching umbrella for SCAR research in Life Sciences. Now is the time for aiming to progress beyond this important role, and the Antarctic biology community is proposing two programmes, focussed on distinct but complementary aspects of polar biology and working across marine, freshwater and terrestrial environments: "State of the Antarctic Ecosystem (AntEco)", and "Antarctic Thresholds--Ecosystem Resilience and Adaptation (AnT-ERA)". These programmes are the legacy of EBA, and they are key to understanding and protect Antarctic biodiversity. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Antarctic krill; assessment of mesh size selectivity and escape mortality from trawls

    DEFF Research Database (Denmark)

    Krafft, Bjørn A.; Krag, Ludvig Ahm; Herrmann, Bent

    2015-01-01

    Marine AS. The project will examine krill escape mortality from the codend during a full scale field experiment, model size selectivity and escape mortality in codends including different designs and assess the size selectivity in the trawl body forward of the codend. Based on end results from the preceding...... examinations we will be able to predict size selectivity and escape mortality from the entire trawl body with the appurtenant mortality for different trawl designs......This working paper presents the aims and methodology for a three-year-project (commenced in 2015) assessing size selectivity and escape mortality of Antarctic krill from trawl nets. The project is widely based on acquired experiences from a completed study Net Escapement of Antarctic krill...

  13. Modeling Antarctic Ice Sheet retreat in warm climates: a historical perspective.

    Science.gov (United States)

    Pollard, D.; Deconto, R. M.; Gasson, E.

    2016-12-01

    Early modeling of Antarctic Ice Sheet size vs. climate focused on asymmetry between retreat and growth, with much greater warming needed to cause retreat from full ice cover, due to Height Mass Balance Feedback and albedo feedback. This led to a long-standing model-data conflict, with models needing 1000 to2000 ppmv atmospheric CO2 to produce retreat from full size, vs. proxy data of large ice fluctuations despite much lower CO2 since the Miocene.Subsequent modeling with marine ice physics found that the West Antarctic Ice Sheet could undergo repeated warm-period collapses with realistic past forcing. However, that yields only 3 to 7 m equivalent sea-level rise above modern, compared to 10 to 20 m or more suggested by some geologic data. Large subglacial basins in East Antarctica could be vulnerable to the same processes,but did not retreat in most models due to narrower and shallower sills.After recent modifications, some ice sheet models were able to produce warm-period collapse of major East Antarctic basins, with sea-level rise of up to 15 m. The modifications are (i) hydrofracturing by surface melt, and structural failure of ice cliffs, or (ii) numerical treatment at the grounding line. In these models, large retreat occurs both for past warmintervals, and also for future business-as-usual scenarios.Some interpretations of data in the late Oligocene and Miocene suggest yet larger fluctuations, between 50 to 100% of modern Antarctic size. That would require surface-melt driven retreat of some terrestrial East Antarctic ice, despite the hysteresis issue raised above. A recent study using a coupled climate-ice sheet model found that with a finer climate gridand more frequent coupling exchange, substantial retreat of terrestrial Antarctica can occur with 500 to 840 ppmv CO2, much lower than in earlier models. This will allow meaningful interactions between modeling and deeper-time geologic interpretations since the late Oligocene.

  14. Effects of euthanasia method on stable-carbon and stable-nitrogen isotope analysis for an ectothermic vertebrate.

    Science.gov (United States)

    Atwood, Meredith A

    2013-04-30

    Stable isotope analysis is a critical tool for understanding ecological food webs; however, results can be sensitive to sample preparation methods. To limit the possibility of sample contamination, freezing is commonly used to euthanize invertebrates and preserve non-lethal samples from vertebrates. For destructive sampling of vertebrates, more humane euthanasia methods are preferred to freezing and it is essential to evaluate how these euthanasia methods affect stable isotope results. Stable isotope ratios and elemental composition of carbon and nitrogen were used to evaluate whether the euthanasia method compromised the integrity of the sample for analysis. Specifically, the stable isotope and C:N ratios were compared for larval wood frogs (Rana sylvatica  =  Lithobates sylvaticus), an ectothermic vertebrate, that had been euthanized by freezing with four different humane euthanasia methods: CO2, benzocaine, MS-222 (tricaine methanesulfonate), and 70% ethanol. The euthanasia method was not related to the δ(13)C or δ(15)N values and the comparisons revealed no differences between freezing and any of the other treatments. However, there were slight (non-significant) differences in the isotope ratios of benzocaine and CO2 when each was compared with freezing. The elemental composition was altered by the euthanasia method employed. The percentage nitrogen was higher in CO2 treatments than in freezing, and similar (non-significant) trends were seen for ethanol treatments relative to freezing. The resulting C:N ratios were higher for benzocaine treatments than for both CO2 and ethanol. Similar (non-significant) trends suggested that the C:N ratios were also higher for animals euthanized by freezing than for both CO2 and ethanol euthanasia methods. The euthanasia method had a larger effect on elemental composition than stable isotope ratios. The percentage nitrogen and the subsequent C:N ratios were most affected by the CO2 and ethanol euthanasia methods, whereas

  15. Health aspects of Antarctic tourism.

    Science.gov (United States)

    Prociv, P

    1998-12-01

    Increasing numbers of seaborne tourists are visiting Antarctica, with most coming from the United States (3503 in 1996-97), Germany (777), and Australia (680; cf. 356 in 1994-95 and 410 in 1995-96). The impression among travel medicine clinicians is that, each year, more prospective travelers seek advice about the health demands of this type of adventure, mostly relating to fitness for travel, exposure to extreme cold, hazards in ice and snow, and other potential health risks. This is a recent phenomenon. While a regular shipping service had been established between the Falklands and the subantarctic islands of South Georgia and the South Shetlands by 1924, the first documented tourists accompanied an Argentine expedition to the South Orkneys in 1933.1 Commercial airline flights over these islands and the Antarctic Peninsula began in 1956, from Chile, and recreational cruises to the Peninsula began in 1958. Tourist numbers subsequently grew slowly, for what was clearly an exclusive and very expensive undertaking, with few ships available for these hazardous voyages. From 1957 to 1993, 37,000 tourists visited by sea, most seeing only the Peninsula.2 The dramatic recent growth in numbers is a consequence of the collapse of the Soviet Union. The small fleet of ice-strengthened research vessels and working icebreakers, which was made redundant by withdrawal of central government support from isolated communities and military activities along the northern coast of Siberia (and from Antarctic research bases), now accounts for the bulk of charter-cruise tourism to Antarctica, at competitive prices. According to the International Association of Antarctica Tour Operators,3 7322 people traveled to Antarctica on commercially organized voyages in the 1996-97 season, and a record 10,000 shipborne visitors were expected for the 1997-98 season (November-March), traveling mainly from South America to the Peninsula on 15 ice-reinforced vessels, each carrying between 36 and 180

  16. Regulation of acid-base status in ectothermic vertebrates: the consequences for oxygen pressures in lung gas and arterial blood.

    Science.gov (United States)

    Glass, M L; Soncini, R

    1995-01-01

    Extensive literature reports a negative delta pHa/delta t in ectothermic vertebrates, but data are scarce as to its consequences for O2 transport. In reptiles, the negative delta pHa/delta t results from an elevated lung gas PCO2 (PACO2) at higher temperatures, implying a corresponding fall of PAO2. In parallel, arterial PO2 rises with temperature, due to a combination of central vascular shunt and decreasing Hb.O2 affinity. As a result, the PO2 gradient between lung gas and blood (PA-aO2) becomes reduced at higher temperatures. In amphibians, the negative delta pHa/delta t results from combined cutaneous and pulmonary CO2 elimination. We propose that this leads to a rather temperature-independent lung gas PO2. Moreover, our calculations suggest that resting reptiles and amphibians maintain a relatively large PA-aO2 also at high temperatures. The negative delta pHa/delta t in teleost fish is generally considered to be a result of modulated plasma [HCO3-]. Recent data from our laboratory suggest that acute pH adjustments at high temperatures may involve alterations of PaCO2 through gill ventilation, leading to a decrease of PaO2 with rising temperature.

  17. Marine cloud brightening: regional applications.

    Science.gov (United States)

    Latham, John; Gadian, Alan; Fournier, Jim; Parkes, Ben; Wadhams, Peter; Chen, Jack

    2014-12-28

    The general principle behind the marine cloud brightening (MCB) climate engineering technique is that seeding marine stratocumulus clouds with substantial concentrations of roughly monodisperse sub-micrometre-sized seawater particles might significantly enhance cloud albedo and longevity, thereby producing a cooling effect. This paper is concerned with preliminary studies of the possible beneficial application of MCB to three regional issues: (1) recovery of polar ice loss, (2) weakening of developing hurricanes and (3) elimination or reduction of coral bleaching. The primary focus is on Item 1. We focus discussion herein on advantages associated with engaging in limited-area seeding, regional effects rather than global; and the levels of seeding that may be required to address changing current and near-term conditions in the Arctic. We also mention the possibility that MCB might be capable of producing a localized cooling to help stabilize the West Antarctic Ice Sheet.

  18. Antarctic station life: The first 15 years of mixed expeditions to the Antarctic

    Science.gov (United States)

    Sarris, Aspa

    2017-02-01

    This study examined the experiences of women who lived and worked on remote and isolated Antarctic stations for up to 15 months at a time. The study employed purposeful sampling and a longitudinal - processual approach to study women's experiences over the first 15 years of mixed gender Antarctic expeditions. The retrospective analysis was based on a semi-structured interview administered to 14 women upon their return to Australia. The results showed that women referred to the natural physical Antarctic environment as one of the best aspects of their experience and the reason they would recommend the Antarctic to their friends as a good place to work. In describing the worst aspect of their experience, women referred to aspects of Antarctic station life, including: (i) the male dominated nature of station culture; (ii) the impact of interpersonal conflict, including gender based conflict and friction between scientists and trades workers; and (iii) the lack of anonymity associated with living and working with the same group of individuals, mainly men, for up to 12 months or more. The results are discussed within the context of the evolution of Antarctic station culture and recommendations are made in terms of the demography of expeditions, expeditioner selection and recruitment and the ongoing monitoring of Antarctic station culture. The study presents a framework that can be applied to groups and teams living and working in analogous isolated, confined and extreme work environments, including outer space missions.

  19. Meteorological observatory for Antarctic data collection

    International Nuclear Information System (INIS)

    Grigioni, P.; De Silvestri, L.

    1996-01-01

    In the last years, a great number of automatic weather stations was installed in Antarctica, with the aim to examine closely the weather and climate of this region and to improve the coverage of measuring points on the Antarctic surface. In 1987 the Italian Antarctic Project started to set up a meteorological network, in an area not completely covered by other countries. Some of the activities performed by the meteorological observatory, concerning technical functions such as maintenance of the AWS's and the execution of radio soundings, or relating to scientific purposes such as validation and elaboration of collected data, are exposed. Finally, some climatological considerations on the thermal behaviour of the Antarctic troposphere such as 'coreless winter', and on the wind field, including katabatic flows in North Victoria Land are described

  20. Tephra compositions from Late Quaternary volcanoes around the Antarctic Peninsula

    Science.gov (United States)

    Kraus, S.

    2009-12-01

    /Hf ratios lower than N-MORB, all other volcanoes including the Larsen Rift centers display Zr/Hf higher than N-MORB. It is expected that the correlation of the new data with published data from tephra layers found in ice, lake and marine sediment cores will contribute to a better constrained timing of individual climatic events identified in the northern Antarctic Peninsula area. Late Quaternary volcanoes around the northern Antarctic Peninsula.

  1. Chilean Antarctic Stations on King George Island

    Directory of Open Access Journals (Sweden)

    Katsutada Kaminuma

    2000-07-01

    Full Text Available The purpose of my visit to Chilean Antarctic Stations was to assess the present status of geophysical observations and research, as the South Shetland Island, West Antarctica, where the stations are located, are one of the most active tectonic regions on the Antarctic plate. The Instituto Antartico Chileno (INACH kindly gave me a chance to stay in Frei/Escudero Bases as an exchange scientist under the Antarctic Treaty for two weeks in January 2000. I stayed in Frei Base as a member of a geological survey group named "Tectonic Evolution of the Antarctic Peninsula" which was organized by Prof. F. Herve, University of Chile, from January 05 to 19,2000. All my activity in the Antarctic was organized by INACH. During my stay in Frei Base, I also visited Bellingshausen (Russian, Great Wall (China and Artigas (Uruguay stations. All these stations are located within walking distance of Frei Base. King Sejong Station (Korea, located 10km east from Frei Base, and Jubany Base (Argentine, another 6km south-east from King Sejong Station, were also visited with the aid of a zodiac boat that was kindly operated for us by King Sejong Station. All stations except Escudero Base carry out meteorological observations. The seismological observations in Frei Base are operated by Washington State University of the U. S. monitoring of earthquake activity and three-component geomagnetic observations are done at King Sejong and Great Wall stations. Earth tide is monitored at Artigas Base. Continuous monitoring of GPS and gravity change are planned at King Sejong Station in the near future. Scientific research activities of each country in the area in the 1999/2000 Antarctic summer season were studied and the logistic ability of all stations was also assessed for our future international cooperation.

  2. Mysterious iodine-overabundance in Antarctic meteorites

    Science.gov (United States)

    Dreibus, G.; Waenke, H.; Schultz, L.

    1986-01-01

    Halogen as well as other trace element concentrations in meteorite finds can be influenced by alteration processes on the Earth's surface. The discovery of Antarctic meteorites offered the opportunity to study meteorites which were kept in one of the most sterile environment of the Earth. Halogen determination in Antartic meteorites was compared with non-Antarctic meteorites. No correlation was found between iodine concentration and the weathering index, or terrestrial age. The halogen measurements indicate a contaminating phase rich in iodine and also containing chlorine. Possible sources for this contamination are discussed.

  3. Mysterious iodine-overabundance in Antarctic meteorites

    International Nuclear Information System (INIS)

    Dreibus, G.; Waenke, H.; Schultz, L.

    1986-01-01

    Halogen as well as other trace element concentrations in meteorite finds can be influenced by alteration processes on the Earth's surface. The discovery of Antarctic meteorites offered the opportunity to study meteorites which were kept in one of the most sterile environment of the Earth. Halogen determination in Antartic meteorites was compared with non-Antarctic meteorites. No correlation was found between iodine concentration and the weathering index, or terrestrial age. The halogen measurements indicate a contaminating phase rich in iodine and also containing chlorine. Possible sources for this contamination are discussed

  4. Bacterial diversity of autotrophic enriched cultures from remote, glacial Antarctic, Alpine and Andean aerosol, snow and soil samples

    Directory of Open Access Journals (Sweden)

    E. González-Toril

    2009-01-01

    Full Text Available Four different communities and one culture of autotrophic microbial assemblages were obtained by incubation of samples collected from high elevation snow in the Alps (Mt. Blanc area and the Andes (Nevado Illimani summit, Bolivia, from Antarctic aerosol (French station Dumont d'Urville and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas, in a minimal mineral (oligotrophic media. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. Phylogenetic comparison with the currently available rDNA database allowed sequences belonging to Proteobacteria Alpha-, Beta- and Gamma-proteobacteria, Actinobacteria and Bacteroidetes phyla to be identified. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified and the marine Antarctic soil the poorest (only one. Snow samples from Col du Midi (Alps and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones. These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteriaclone. The only microorganism identified in the Antarctica soil (Brevundimonas sp. was also detected in the Antarctic aerosol. Most of the identified microorganisms had been detected previously in cold environments, marine sediments soils and rocks. Air current dispersal is the best model to explain the presence of very specific microorganisms, like those identified in this work, in environments very distant and very different from each other.

  5. Ice age aerosol content from east Antarctic ice core samples and past wind strength

    International Nuclear Information System (INIS)

    Petit, J.R.; Briat, M.; Royer, A.

    1981-01-01

    The possible link between the aerosol content from the 905 deep Dome C ice core (East Antartica) which spans some 32,000 yr (Lorius et al. Nature; 280:644 (1979)) and climate, is considered. No evidence of major global or local volcanic activity was found though large marine and continental inputs (respectively 5 and 20 times higher than present) were observed at the end of the last Glacial stage. It is considered that they reflect glacial age climate with stronger atmospheric circulation, enhanced aridity and faster aerosol transport towards the Antarctic continent. (U.K.)

  6. Constraining the Antarctic contribution to global sea-level change: ANDRILL and beyond

    Science.gov (United States)

    Naish, Timothy

    2016-04-01

    Observations, models and paleoclimate reconstructions suggest that Antarctica's marine-based ice sheets behave in an unstable manner with episodes of rapid retreat in response to warming climate. Understanding the processes involved in this "marine ice sheet instability" is key for improving estimates of Antarctic ice sheet contribution to future sea-level rise. Another motivating factor is that far-field sea-level reconstructions and ice sheet models imply global mean sea level (GMSL) was up to 20m and 10m higher, respectively, compared with present day, during the interglacials of the warm Pliocene (~4-3Ma) and Late Pleistocene (at ~400ka and 125ka). This was when atmospheric CO2 was between 280 and 400ppm and global average surface temperatures were 1 to 3°C warmer, suggesting polar ice sheets are highly sensitive to relatively modest increases in climate forcing. Such magnitudes of GMSL rise not only require near complete melt of the Greenland Ice Sheet and the West Antarctic Ice Sheet, but a substantial retreat of marine-based sectors of East Antarctic Ice Sheet. Recent geological drilling initiatives on the continental margin of Antarctica from both ship- (e.g. IODP; International Ocean Discovery Program) and ice-based (e.g. ANDRILL/Antarctic Geological Drilling) platforms have provided evidence supporting retreat of marine-based ice. However, without direct access through the ice sheet to archives preserved within sub-glacial sedimentary basins, the volume and extent of ice sheet retreat during past interglacials cannot be directly constrained. Sediment cores have been successfully recovered from beneath ice shelves by the ANDRILL Program and ice streams by the WISSARD (Whillans Ice Stream Sub-glacial Access Research Drilling) Project. Together with the potential of the new RAID (Rapid Access Ice Drill) initiative, these demonstrate the technological feasibility of accessing the subglacial bed and deeper sedimentary archives. In this talk I will outline the

  7. Lichen flora around the Korean Antarctic Scientific Station, King George Island, Antarctic.

    Science.gov (United States)

    Kim, Ji Hee; Ahn, In-Young; Hong, Soon Gyu; Andreev, Mikhail; Lim, Kwang-Mi; Oh, Mi Jin; Koh, Young Jin; Hur, Jae-Seoun

    2006-10-01

    As part of the long-term monitoring projects on Antarctic terrestrial vegetation in relation to global climate change, a lichen floristical survey was conducted around the Korean Antarctic Station (King Sejong Station), which is located on Barton Peninsula, King George Island, in January and February of 2006. Two hundred and twenty-five lichen specimens were collected and sixty-two lichen species in 38 genera were identified by morphological characteristics, chemical constituents, TLC analysis and ITS nucleotide sequence analysis.

  8. Aerosols in King George Island (Antarctic peninsula) using PIXE and alpha spectrometry

    International Nuclear Information System (INIS)

    Dias da Cunha, K.; Medeiros, G.; Leal, M.A.; Lima, C.; Dalia, K.C.

    2009-01-01

    The aim of this study was to characterize the airborne particles and particles deposited in the recent snow samples collected at King George Island (Admiralty Bay) in order to evaluate the possible local sources of airborne particles and the aerosol transport from South America to Antarctic at sea level. Airborne particles samples were collected using a cascade impactor and cyclones at several sampling points at Admiralty Bay. Airborne particles were also collected during the ship travel from Rio de Janeiro to Antarctica. The recent snow samples and aerosols collected at several sampling points at Admiralty Bay were analyzed by PIXE for the determination of the elemental mass concentration. Snow samples were analyzed by alpha spectrometry to determine the 232Th, 228Th, 238U and 234U concentrations in snow. The Mass Median Aerodynamic Diameter of airborne particles was determined. The results suggest that there is a correlation between the aerosol samples and the particles deposited in the snow, but the elemental mass distributions are not equal. The snow elemental concentration can be used as an indicator of the elements present in the aerosols. The local aerosol sources (natural and anthropogenic) have been considered to characterize the aerosol transport to Antarctic, mainly King George Island. The main aerosol sources are the marine spray, weathering of local rocks and anthropogenic sources, as the diesel burning in the island. Besides the local aerosol sources the transport of airborne particles from south Atlantic to Antarctic is an important source of airborne particles at King George Island. (author)

  9. Marine ecology

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    Studies on marine ecology included marine pollution; distribution patterns of Pu and Am in the marine waters, sediments, and organisms of Bikini Atoll and the influence of physical, chemical, and biological factors on their movements through marine biogeochemical systems; transfer and dispersion of organic pollutants from an oil refinery through coastal waters; transfer of particulate pollutants, including sediments dispersed during construction of offshore power plants; and raft culture of the mangrove oysters

  10. Marine pollution

    International Nuclear Information System (INIS)

    Albaiges, J.

    1989-01-01

    This book covers the following topics: Transport of marine pollutants; Transformation of pollutants in the marine environment; Biological effects of marine pollutants; Sources and transport of oil pollutants in the Persian Gulf; Trace metals and hydrocarbons in Syrian coastal waters; and Techniques for analysis of trace pollutants

  11. Links between Patagonian Ice Sheet fluctuations and Antarctic dust variability during the last glacial period (MIS 4-2)

    Science.gov (United States)

    Kaiser, Jérôme; Lamy, Frank

    2010-06-01

    Antarctic and Greenland ice-core records reveal large fluctuations of dust input on both orbital and millennial time-scales with potential global climate implications. At least during glacial periods, the Antarctic dust fluctuations appear to be largely controlled by environmental changes in southern South America. We compare dust flux records from two Antarctic ice-cores to variations in the composition of the terrigenous supply at ODP Site 1233 located off southern Chile and known to record fluctuations in the extent of the northern part of the Patagonian ice-sheet (NPIS) during the last glacial period (Marine Isotope Stage, MIS, 4 to 2). Within age uncertainties, millennial-scale glacial advances (retreats) of the NPIS correlate to Antarctic dust maxima (minima). In turn, NPIS fluctuations were closely related to offshore sea surface temperature (SST) changes. This pattern suggests a causal link involving changes in temperature, in rock flour availability, in latitudinal extensions of the westerly winds and in foehn winds in the southern Pampas and Patagonia. We further suggest that the long-term trend of dust accumulation is partly linked to the sea-level related changes in the size if the Patagonian source area due to the particular morphology of the Argentine shelf. We suggest that sea-level drops at the beginning of MIS 4 and MIS 2 were important for long-term dust increases, while changes in the Patagonian dust source regions primarily control the early dust decrease during the MIS 4/3 transition and Termination 1.

  12. Future Antarctic Bed Topography and Its Implications for Ice Sheet Dynamics

    Science.gov (United States)

    Adhikari, Surendra; Ivins, Erik R.; Larour, Eric Y.; Seroussi, Helene L.; Morlighem, Mathieu; Nowicki, S.

    2014-01-01

    The Antarctic bedrock is evolving as the solid Earth responds to the past and ongoing evolution of the ice sheet. A recently improved ice loading history suggests that the Antarctic Ice Sheet (AIS) has generally been losing its mass since the Last Glacial Maximum. In a sustained warming climate, the AIS is predicted to retreat at a greater pace, primarily via melting beneath the ice shelves.We employ the glacial isostatic adjustment (GIA) capability of the Ice Sheet System Model (ISSM) to combine these past and future ice loadings and provide the new solid Earth computations for the AIS.We find that past loading is relatively less important than future loading for the evolution of the future bed topography. Our computations predict that the West Antarctic Ice Sheet (WAIS) may uplift by a few meters and a few tens of meters at years AD 2100 and 2500, respectively, and that the East Antarctic Ice Sheet is likely to remain unchanged or subside minimally except around the Amery Ice Shelf. The Amundsen Sea Sector in particular is predicted to rise at the greatest rate; one hundred years of ice evolution in this region, for example, predicts that the coastline of Pine Island Bay will approach roughly 45mmyr-1 in viscoelastic vertical motion. Of particular importance, we systematically demonstrate that the effect of a pervasive and large GIA uplift in the WAIS is generally associated with the flattening of reverse bed slope, reduction of local sea depth, and thus the extension of grounding line (GL) towards the continental shelf. Using the 3-D higher-order ice flow capability of ISSM, such a migration of GL is shown to inhibit the ice flow. This negative feedback between the ice sheet and the solid Earth may promote stability in marine portions of the ice sheet in the future.

  13. Halogen species record Antarctic sea ice extent over glacial–interglacial periods

    Directory of Open Access Journals (Sweden)

    A. Spolaor

    2013-07-01

    Full Text Available Sea ice is an integral part of the earth's climate system because it affects planetary albedo, sea-surface salinity, and the atmosphere–ocean exchange of reactive gases and aerosols. Bromine and iodine chemistry is active at polar sea ice margins with the occurrence of bromine explosions and the biological production of organoiodine from sea ice algae. Satellite measurements demonstrate that concentrations of bromine oxide (BrO and iodine oxide (IO decrease over sea ice toward the Antarctic interior. Here we present speciation measurements of bromine and iodine in the TALDICE (TALos Dome Ice CorE ice core (159°11' E, 72°49' S; 2315 m a.s.l. spanning the last 215 ky. The Talos Dome ice core is located 250 km inland and is sensitive to marine air masses intruding onto the Antarctic Plateau. Talos Dome bromide (Br− is positively correlated with temperature and negatively correlated with sodium (Na. Based on the Br−/Na seawater ratio, bromide is depleted in the ice during glacial periods and enriched during interglacial periods. Total iodine, consisting of iodide (I− and iodate (IO3−, peaks during glacials with lower values during interglacial periods. Although IO3− is considered the most stable iodine species in the atmosphere it was only observed in the TALDICE record during glacial maxima. Sea ice dynamics are arguably the primary driver of halogen fluxes over glacial–interglacial timescales, by altering the distance between the sea ice edge and the Antarctic plateau and by altering the surface area of sea ice available to algal colonization. Based on our results we propose the use of both halogens for examining Antarctic variability of past sea ice extent.

  14. Future Antarctic bed topography and its implications for ice sheet dynamics

    Science.gov (United States)

    Adhikari, S.; Ivins, E. R.; Larour, E.; Seroussi, H.; Morlighem, M.; Nowicki, S.

    2014-06-01

    The Antarctic bedrock is evolving as the solid Earth responds to the past and ongoing evolution of the ice sheet. A recently improved ice loading history suggests that the Antarctic Ice Sheet (AIS) has generally been losing its mass since the Last Glacial Maximum. In a sustained warming climate, the AIS is predicted to retreat at a greater pace, primarily via melting beneath the ice shelves. We employ the glacial isostatic adjustment (GIA) capability of the Ice Sheet System Model (ISSM) to combine these past and future ice loadings and provide the new solid Earth computations for the AIS. We find that past loading is relatively less important than future loading for the evolution of the future bed topography. Our computations predict that the West Antarctic Ice Sheet (WAIS) may uplift by a few meters and a few tens of meters at years AD 2100 and 2500, respectively, and that the East Antarctic Ice Sheet is likely to remain unchanged or subside minimally except around the Amery Ice Shelf. The Amundsen Sea Sector in particular is predicted to rise at the greatest rate; one hundred years of ice evolution in this region, for example, predicts that the coastline of Pine Island Bay will approach roughly 45 mm yr-1 in viscoelastic vertical motion. Of particular importance, we systematically demonstrate that the effect of a pervasive and large GIA uplift in the WAIS is generally associated with the flattening of reverse bed slope, reduction of local sea depth, and thus the extension of grounding line (GL) towards the continental shelf. Using the 3-D higher-order ice flow capability of ISSM, such a migration of GL is shown to inhibit the ice flow. This negative feedback between the ice sheet and the solid Earth may promote stability in marine portions of the ice sheet in the future.

  15. A New Antarctic Field Course for Undergraduates at Michigan State University

    Science.gov (United States)

    Tweedie, C. E.; Hesse, J.; Hollister, R. D.; Roberts, P.; Wilson, J.; Wilson, M. I.; Webber, P. J.

    2003-12-01

    Field courses in remote and extreme environments immerse students in new and unfamiliar cultural and environmental settings where the impact from learning is high and the conventional wisdom, mindsets, and life skills of students are challenged. Through the Office of Study Abroad at Michigan State University (MSU), a new field course for undergraduates entitled `Studies in Antarctic System Science' embraces these principles. The three week, 6 credit course will be convened for the first time during the 2003-04 austral summer and will feature field based activities and classroom sessions beginning in Ushuaia, Tierra Del Fuego, Argentina. The defining experience of the program will be a cruise of the Antarctic Peninsula on a tourist ship partnered to the International Association of Antarctic Tour Operators (IAATO). This cruise will include landings on a daily basis at various sites of interest and international research stations en route. In 2003-04, the course will comprise 20 students and three faculty members from MSU. The non-major course curriculum has been compiled from materials based on original research by program faculty, relevant literature, information obtained directly from the international research community, and the Antarctic tourist industry. Subject areas will span multiple disciplines including palaeohistory and ecology, oceanography, climatology, geology and glaciology, marine, terrestrial and aerobiology, early exploration, policy and management, and the potential impacts from climate change and humans. It is intended that the course be repeated on an annual basis and that the curriculum be expanded to include greater coverage of ongoing research activities, especially NSF funded research. We welcome contact and feedback from educators and scientists interested in this endeavor, especially those who would like to broaden the impact of their own education interests or research by offering materials that could enhance the curriculum of the course

  16. A metabolic hypothesis for the evolution of temperature effects on the arterial PCO2  and pH of vertebrate ectotherms.

    Science.gov (United States)

    Hillman, Stanley S; Hedrick, Michael S

    2018-01-04

    Body temperature increases in ectothermic vertebrates characteristically lead to both increases in arterial P CO 2  ( P a CO 2 ) and declines in resting arterial pH (pHa) of about 0.017 pH units per 1°C increase in temperature. This 'alphastat' pH pattern has previously been interpreted as being evolutionarily driven by the maintenance of a constant protonation state on the imidazole moiety of histidine protein residues, hence stabilizing protein structure-function. Analysis of the existing data for interclass responses of ectothermic vertebrates shows different degrees of P a CO 2  increases and pH declines with temperature between the classes, with reptiles>amphibians>fish. The P a CO 2  at the temperature where maximal aerobic metabolism ( V̇ O 2 ,max ) is achieved is significantly and positively correlated with temperature for all vertebrate classes. For ectotherms, the P a CO 2  where V̇ O 2 ,max is greatest is also correlated with V̇ O 2 ,max , indicating there is an increased driving force for CO 2 efflux that is lowest in fish, intermediate in amphibians and highest in reptiles. The pattern of increased P a CO 2  and the resultant reduction of pHa in response to increased body temperature would serve to increase CO 2 efflux, O 2 delivery and blood buffering capacity and maintain ventilatory scope. This represents a new hypothesis for the selective advantage of arterial pH regulation from a systems physiology perspective in addition to the advantages of maintenance of protein structure-function. © 2018. Published by The Company of Biologists Ltd.

  17. Marine genomics

    DEFF Research Database (Denmark)

    Oliveira Ribeiro, Ângela Maria; Foote, Andrew David; Kupczok, Anne

    2017-01-01

    Marine ecosystems occupy 71% of the surface of our planet, yet we know little about their diversity. Although the inventory of species is continually increasing, as registered by the Census of Marine Life program, only about 10% of the estimated two million marine species are known. This lag......-throughput sequencing approaches have been helping to improve our knowledge of marine biodiversity, from the rich microbial biota that forms the base of the tree of life to a wealth of plant and animal species. In this review, we present an overview of the applications of genomics to the study of marine life, from...

  18. Protein metabolism in marine animals: the underlying mechanism of growth.

    Science.gov (United States)

    Fraser, Keiron P P; Rogers, Alex D

    2007-01-01

    Growth is a fundamental process within all marine organisms. In soft tissues, growth is primarily achieved by the synthesis and retention of proteins as protein growth. The protein pool (all the protein within the organism) is highly dynamic, with proteins constantly entering the pool via protein synthesis or being removed from the pool via protein degradation. Any net change in the size of the protein pool, positive or negative, is termed protein growth. The three inter-related processes of protein synthesis, degradation and growth are together termed protein metabolism. Measurement of protein metabolism is vital in helping us understand how biotic and abiotic factors affect growth and growth efficiency in marine animals. Recently, the developing fields of transcriptomics and proteomics have started to offer us a means of greatly increasing our knowledge of the underlying molecular control of protein metabolism. Transcriptomics may also allow us to detect subtle changes in gene expression associated with protein synthesis and degradation, which cannot be detected using classical methods. A large literature exists on protein metabolism in animals; however, this chapter concentrates on what we know of marine ectotherms; data from non-marine ectotherms and endotherms are only discussed when the data are of particular relevance. We first consider the techniques available to measure protein metabolism, their problems and what validation is required. Protein metabolism in marine organisms is highly sensitive to a wide variety of factors, including temperature, pollution, seasonality, nutrition, developmental stage, genetics, sexual maturation and moulting. We examine how these abiotic and biotic factors affect protein metabolism at the level of whole-animal (adult and larval), tissue and cellular protein metabolism. Available gene expression data, which help us understand the underlying control of protein metabolism, are also discussed. As protein metabolism appears to

  19. A recent case of Antarctic bioprospecting from Japan

    Directory of Open Access Journals (Sweden)

    Akiho Shibata

    2010-03-01

    Full Text Available Antarctic bioprospecting, namely the search for valuable genetic or chemical compounds in Antarctic nature, has been the subject of intense discussion within Antarctic Treaty Consultative Meetings. In this discussion, based on the so-called "end-users view point," utilizing the patent database to see how much Antarctic biological material has been used in patents, Antarctic bioprospecting has been depicted as a lucrative commercial activity operated by big multinational companies. This paper, instead, proposes an "access view point" for Antarctic bioprospecting, by examining a recent Japanese case in which scientists participating in the Japanese Antarctic Research Expedition in 2007 collected some sediment from Antarctic lakes near Syowa Station, isolated and cultured a particular fungus, and found the first evidence of the presence of antifreezing activity in oomycetes. In 2009, the scientists' affiliate institutions, including the National Institute of Advanced Industrial Science and Technology, applied for a patent on Antarctomyces psychrotrophicus Syw-1 and the antifreeze protein obtained from it. A detailed examination of this case demonstrates that the dichotomy of Antarctic bioprospecting into "commercial" and "scientific" does not reflect the reality of bioprospecting activities and, therefore, does not provide an appropriate ground for legal and policy discussion on Antarctic bioprospecting.

  20. Molecular ecophysiology of Antarctic notothenioid fishes.

    Science.gov (United States)

    Cheng, C-H Christina; Detrich, H William

    2007-12-29

    The notothenioid fishes of the Southern Ocean surrounding Antarctica are remarkable examples of organismal adaptation to extreme cold. Their evolution since the mid-Miocene in geographical isolation and a chronically cold marine environment has resulted in extreme stenothermality of the extant species. Given the unique thermal history of the notothenioids, one may ask what traits have been gained, and conversely, what characters have been lost through change in the information content of their genomes. Two dramatic changes that epitomize such evolutionary transformations are the gain of novel antifreeze proteins, which are obligatory for survival in icy seawater, by most notothenioids and the paradoxical loss of respiratory haemoproteins and red blood cells, normally deemed indispensable for vertebrate life, by the species of a highly derived notothenioid family, the icefishes. Here, we review recent advances in our understanding of these traits and their evolution and suggest future avenues of investigation. The formerly coherent paradigm of notothenioid freeze avoidance, developed from three decades of study of antifreeze glycoprotein (AFGP) based cold adaptation, now faces challenges stemming from the recent discovery of antifreeze-deficient, yet freeze-resistant, early notothenioid life stages and from definitive evidence that the liver is not the physiological source of AFGPs in notothenioid blood. The resolution of these intriguing observations is likely to reveal new physiological traits that are unique to the notothenioids. Similarly, the model of AFGP gene evolution from a notothenioid pancreatic trypsinogen-like gene precursor is being expanded and refined based on genome-level analyses of the linked AFGP loci and their ancestral precursors. Finally, the application of comparative genomics to study evolutionary change in the AFGP genotypes of cool-temperate notothenioids from sub-Antarctic habitats, where these genes are not necessary, will contribute to

  1. The Antarctic Master Directory -- the Electronic Card Catalog of Antarctic Data

    Science.gov (United States)

    Scharfen, G.; Bauer, R.

    2003-12-01

    The Antarctic Master Directory (AMD) is a Web-based, searchable record of thousands of Antarctic data descriptions. These data descriptions contain information about what data were collected, where they were collected, when they were collected, who the scientists are, who the point of contact is, how to get the data, and information about the format of the data and what documentation and bibliographic information exists. With this basic descriptive information about content and access for thousands of Antarctic scientific data sets, the AMD is a resource for scientists to advertise the data they have collected and to search for data they need. The AMD has been created by more than twenty nations which conduct research in the Antarctic under the auspices of the Antarctic Treaty. It is a part of the International Directory Network/Global Change Master Directory (IDN/GCMD). Using the AMD is easy. Users can search on subject matter key words, data types, geographic place-names, temporal or spatial ranges, or conduct free-text searches. To search the AMD go to: http://gcmd.nasa.gov/Data/portals/amd/. Contributing your own data descriptions for Antarctic data that you have collected is also easy. Scientists can start by submitting a short data description first (as a placeholder in the AMD, and to satisfy National Science Foundation (NSF) reporting requirements), and then add to, modify or update their record whenever it is appropriate. An easy to use on-line tool and a simple tutorial are available at: http://nsidc.org/usadcc. With NSF Office of Polar Programs (OPP) funding, the National Snow and Ice Data Center (NSIDC) operates the U.S. Antarctic Data Coordination Center (USADCC), partly to assist scientists in using and contributing to the AMD. The USADCC website is at http://nsidc.org/usadcc.

  2. Levoglucosan indicates high levels of biomass burning aerosols over oceans from the Arctic to Antarctic.

    Science.gov (United States)

    Hu, Qi-Hou; Xie, Zhou-Qing; Wang, Xin-Ming; Kang, Hui; Zhang, Pengfei

    2013-11-01

    Biomass burning is known to affect air quality, global carbon cycle, and climate. However, the extent to which biomass burning gases/aerosols are present on a global scale, especially in the marine atmosphere, is poorly understood. Here we report the molecular tracer levoglucosan concentrations in marine air from the Arctic Ocean through the North and South Pacific Ocean to Antarctica during burning season. Levoglucosan was found to be present in all regions at ng/m(3) levels with the highest atmospheric loadings present in the mid-latitudes (30°-60° N and S), intermediate loadings in the Arctic, and lowest loadings in the Antarctic and equatorial latitudes. As a whole, levoglucosan concentrations in the Southern Hemisphere were comparable to those in the Northern Hemisphere. Biomass burning has a significant impact on atmospheric Hg and water-soluble organic carbon (WSOC) from pole-to-pole, with more contribution to WSOC in the Northern Hemisphere than in the Southern Hemisphere.

  3. Effects of sea-ice extent and krill or salp dominance on the Antarctic food web

    Science.gov (United States)

    Loeb, V.; Siegel, V.; Holm-Hansen, O.; Hewitt, R.; Fraser, W.; Trivelpiece, W.; Trivelpiece, S.

    1997-06-01

    Krill (Euphausia superba) provide a direct link between primary producers and higher trophic levels in the Antarctic marine food web. The pelagic tunicate Salpa thompsoni can also be important during spring and summer through the formation of extensive and dense blooms. Although salps are not a major dietary item for Antarctic vertebrate predators,, their blooms can affect adult krill reproduction and survival of krill larvae. Here we provide data from 1995 and 1996 that support hypothesized relationships between krill, salps and region-wide sea-ice conditions,. We have assessed salp consumption as a proportion of net primary production, and found correlations between herbivore densities and integrated chlorophyll-a that indicate that there is a degree of competition between krill and salps. Our analysis of the relationship between annual sea-ice cover and a longer time series of air temperature measurements, indicates a decreased frequency of winters with extensive sea-ice development over the last five decades. Our data suggest that decreased krill availability may affect the levels of their vertebrate predators. Regional warming and reduced krill abundance therefore affect the marine food web and krill resource management.

  4. Emerging spatial patterns in Antarctic prokaryotes.

    Science.gov (United States)

    Chong, Chun-Wie; Pearce, David A; Convey, Peter

    2015-01-01

    Recent advances in knowledge of patterns of biogeography in terrestrial eukaryotic organisms have led to a fundamental paradigm shift in understanding of the controls and history of life on land in Antarctica, and its interactions over the long term with the glaciological and geological processes that have shaped the continent. However, while it has long been recognized that the terrestrial ecosystems of Antarctica are dominated by microbes and their processes, knowledge of microbial diversity and distributions has lagged far behind that of the macroscopic eukaryote organisms. Increasing human contact with and activity in the continent is leading to risks of biological contamination and change in a region whose isolation has protected it for millions of years at least; these risks may be particularly acute for microbial communities which have, as yet, received scant recognition and attention. Even a matter apparently as straightforward as Protected Area designation in Antarctica requires robust biodiversity data which, in most parts of the continent, remain almost completely unavailable. A range of important contributing factors mean that it is now timely to reconsider the state of knowledge of Antarctic terrestrial prokaryotes. Rapid advances in molecular biological approaches are increasingly demonstrating that bacterial diversity in Antarctica may be far greater than previously thought, and that there is overlap in the environmental controls affecting both Antarctic prokaryotic and eukaryotic communities. Bacterial dispersal mechanisms and colonization patterns remain largely unaddressed, although evidence for regional evolutionary differentiation is rapidly accruing and, with this, there is increasing appreciation of patterns in regional bacterial biogeography in this large part of the globe. In this review, we set out to describe the state of knowledge of Antarctic prokaryote diversity patterns, drawing analogy with those of eukaryote groups where appropriate

  5. From transcriptome to biological function: environmental stress in an ectothermic vertebrate, the coral reef fish Pomacentrus moluccensis

    Directory of Open Access Journals (Sweden)

    Ward Alister C

    2007-10-01

    Full Text Available Abstract Background Our understanding of the importance of transcriptional regulation for biological function is continuously improving. We still know, however, comparatively little about how environmentally induced stress affects gene expression in vertebrates, and the consistency of transcriptional stress responses to different types of environmental stress. In this study, we used a multi-stressor approach to identify components of a common stress response as well as components unique to different types of environmental stress. We exposed individuals of the coral reef fish Pomacentrus moluccensis to hypoxic, hyposmotic, cold and heat shock and measured the responses of approximately 16,000 genes in liver. We also compared winter and summer responses to heat shock to examine the capacity for such responses to vary with acclimation to different ambient temperatures. Results We identified a series of gene functions that were involved in all stress responses examined here, suggesting some common effects of stress on biological function. These common responses were achieved by the regulation of largely independent sets of genes; the responses of individual genes varied greatly across different stress types. In response to heat exposure over five days, a total of 324 gene loci were differentially expressed. Many heat-responsive genes had functions associated with protein turnover, metabolism, and the response to oxidative stress. We were also able to identify groups of co-regulated genes, the genes within which shared similar functions. Conclusion This is the first environmental genomic study to measure gene regulation in response to different environmental stressors in a natural population of a warm-adapted ectothermic vertebrate. We have shown that different types of environmental stress induce expression changes in genes with similar gene functions, but that the responses of individual genes vary between stress types. The functions of heat

  6. Environmental constraints on West Antarctic ice-sheet formation

    Energy Technology Data Exchange (ETDEWEB)

    Lindstrom, D R; MacAyeal, D R

    1987-01-01

    Small perturbations in Antarctic environmental conditions can culminate in the demise of the Antarctic ice sheet's western sector. This may have happened during the last interglacial period, and could recur within the next millennium due to atmospheric warming from trace gas and CO/sub 2/ increases. In this study, we investigate the importance of sea-level, accumulation rate, and ice influx from the East Antarctic ice sheet in the re-establishment of the West Antarctic ice sheet from a thin cover using a time-dependent numerical ice-shelf model. Our results show that a precursor to the West Antarctic ice sheet can form within 3000 years. Sea-level lowering caused by ice-sheet development in the Northern Hemisphere has the greatest environmental influence. Under favorable conditions, ice grounding occurs over all parts of the West Antarctic ice sheet except up-stream of Thwaites Glacier and in the Ross Sea region.

  7. A geoelectrical survey above an Antarctic ice shelf

    Directory of Open Access Journals (Sweden)

    M. Pavan

    1998-06-01

    Full Text Available A geoelectrical survey was performed on the Hells Gate ice shelf (Victoria Land-Antarctic within the framework of an integrated geophysical and glaciological research program. The resistivity profiles show a similar trend, with resistivity values ranging from about 25000 W · m to 500000 W · m. These results have been interpreted as the effect of a sharp transition from "marine ice" to "continental" ice an interpretation that is consistent with the results of surface mapping. Interpreting the Vertical Electrical Soundings (VES is a complex process. In fact, the alternating layers of ice with different compositions and salt content generate great uncertainty relative to the corresponding electric stratigraphies. To solve these problems of equivalency, all the available constraints were used including the drilling thickness, seismic reflection profiles as well as radar profiles. The results were used to provide what is mainly a qualitative overview that is coherent with the glaciological hypotheses relative to the evolution and structure proposed by some researchers for this ice shelf.

  8. MECHANISMS FOR THE SEASONAL CYCLE IN THE ANTARCTIC COASTAL OCEANS

    OpenAIRE

    オオシマ; Kay I., OHSHIMA

    1996-01-01

    Seasonal variations of the Antarctic coastal oceans has not been well understood owing to logistical difficulties in observations, especially during the ice-covered season. Recently, 'Weddell Gyre Study' and 'Japanese Antarctic Climate Research program' have revealed the following seasonal variations in the Antarctic coastal ocean. First, the thickness of the Winter Water (WW) layer, characterized by cold, fresh, oxygen-rich water, exhibits its maximum in the austral fall and its minimum in t...

  9. Thermoregulation and temperature relations of alligators and other large ectotherms inhabiting thermally stressed habitats. Progress report, 1 October 1974--30 September 1977

    International Nuclear Information System (INIS)

    Spotila, J.R.

    1977-06-01

    Significant progress has been made in determining the mechanisms by which large ectotherms adjust to thermal stress in their natural environment. The effect of mouth gaping on head temperatures and the role of radiation, conduction and convection on body temperatures of alligators have been determined. The utility of energy budget modeling as a method for studying the thermoregulatory mechanisms of animals has been demonstrated. Steady state and time dependent models of body temperature have been tested. Convection coefficients and evaporative water loss rates have been measured for the turtle, Chysemys scripta. Climate space diagrams have been formulated and are being tested. Behavioral thermoregulation of turtles has been studied in PAR pond on the Savannah River Plant, Aiken, S.C. Steady state energy budget equations have been computed for largemouth bass. Experimental heat transfer coefficients indicate that most heat transfer is through the body wall and not via the gills. A time dependent model is being tested. It predicts the body temperature of a fish in a heterothermal environment. Theoretical calculations have been made of the effects of body size, color, and metabolism on the temperature regulation of ectotherms

  10. Antarctic Meteorite Classification and Petrographic Database

    Science.gov (United States)

    Todd, Nancy S.; Satterwhite, C. E.; Righter, Kevin

    2011-01-01

    The Antarctic Meteorite collection, which is comprised of over 18,700 meteorites, is one of the largest collections of meteorites in the world. These meteorites have been collected since the late 1970's as part of a three-agency agreement between NASA, the National Science Foundation, and the Smithsonian Institution [1]. Samples collected each season are analyzed at NASA s Meteorite Lab and the Smithsonian Institution and results are published twice a year in the Antarctic Meteorite Newsletter, which has been in publication since 1978. Each newsletter lists the samples collected and processed and provides more in-depth details on selected samples of importance to the scientific community. Data about these meteorites is also published on the NASA Curation website [2] and made available through the Meteorite Classification Database allowing scientists to search by a variety of parameters

  11. Satellite magnetic anomalies of the Antarctic crust

    Directory of Open Access Journals (Sweden)

    D. E. Alsdorf

    2000-06-01

    Full Text Available Spatially and temporally static crustal magnetic anomalies are contaminated by static core field effects above spherical harmonic degree 12 and dynamic, large-amplitude external fields. To extract crustal magnetic anomalies from the measurements of NASA's Magsat mission, we separate crustal signals from both core and external field effects. In particular, we define Magsat anomalies relative to the degree 11 field and use spectral correlation theory to reduce them for external field effects. We obtain a model of Antarctic crustal thickness by comparing the region's terrain gravity effects to free-air gravity anomalies derived from the Earth Gravity Model 1996 (EGM96. To separate core and crustal magnetic effects, we obtain the pseudo-magnetic effect of the crustal thickness variations from their gravity effect via Poisson's theorem for correlative potentials. We compare the pseudo-magnetic effect of the crustal thickness variations to field differences between degrees 11 and 13 by spectral correlation analysis. We thus identify and remove possible residual core field effects in the Magsat anomalies relative to the degree 11 core field. The resultant anomalies reflect possible Antarctic contrasts due both to crustal thickness and intracrustal variations of magnetization. In addition, they provide important constraints on the geologic interpretation of aeromagnetic survey data, such as are available for the Weddell Province. These crustal anomalies also may be used to correct for long wavelength errors in regional compilations of near-surface magnetic survey data. However, the validity of these applications is limited by the poor quality of the Antarctic Magsat data that were obtained during austral Summer and Fall when south polar external field activity was maximum. Hence an important test and supplement for the Antarctic crustal Magsat anomaly map will be provided by the data from the recently launched Ørsted mission, which will yield coverage

  12. Antarctic carbonaceous chondrites - New opportunities for research

    Science.gov (United States)

    McSween, Harry Y., Jr.

    An account is given of the types of carbonaceous meteorites available in the Antarctic collections of the U.S. and Japan. In the case of the collection for Victoria Land and Queen Maud Land, all known classes for meteorites except C1 are present; available pairing data, though limited, are indicative of the presence of many different falls. Thus far, attention has been focused on the largest meteorites. Most samples, however, are small.

  13. Structural Uncertainty in Antarctic sea ice simulations

    Science.gov (United States)

    Schneider, D. P.

    2016-12-01

    The inability of the vast majority of historical climate model simulations to reproduce the observed increase in Antarctic sea ice has motivated many studies about the quality of the observational record, the role of natural variability versus forced changes, and the possibility of missing or inadequate forcings in the models (such as freshwater discharge from thinning ice shelves or an inadequate magnitude of stratospheric ozone depletion). In this presentation I will highlight another source of uncertainty that has received comparatively little attention: Structural uncertainty, that is, the systematic uncertainty in simulated sea ice trends that arises from model physics and mean-state biases. Using two large ensembles of experiments from the Community Earth System Model (CESM), I will show that the model is predisposed towards producing negative Antarctic sea ice trends during 1979-present, and that this outcome is not simply because the model's decadal variability is out-of-synch with that in nature. In the "Tropical Pacific Pacemaker" ensemble, in which observed tropical Pacific SST anomalies are prescribed, the model produces very realistic atmospheric circulation trends over the Southern Ocean, yet the sea ice trend is negative in every ensemble member. However, if the ensemble-mean trend (commonly interpreted as the forced response) is removed, some ensemble members show a sea ice increase that is very similar to the observed. While this results does confirm the important role of natural variability, it also suggests a strong bias in the forced response. I will discuss the reasons for this systematic bias and explore possible remedies. This an important problem to solve because projections of 21st -Century changes in the Antarctic climate system (including ice sheet surface mass balance changes and related changes in the sea level budget) have a strong dependence on the mean state of and changes in the Antarctic sea ice cover. This problem is not unique to

  14. America on the Ice. Antarctic Policy Issues

    Science.gov (United States)

    1990-01-01

    Malay- sian Prime Minister- Mahatir Mohamad-fired the open- ing volleys during a UN General Assembly speech in September of that year. He noted...define the problem of unin- habited lands." According to Mahatir , the Antarctic conti- nent clearly qualified for such consideration and, not... Mahatir , 109 Molodezhnaya station, 124 Moon Treaty (1979), 108 Mount Erebus, 134 Myhre, Jeffrey, 59 NASA. See National Aeronautics and Space

  15. Marine biology

    International Nuclear Information System (INIS)

    Thurman, H.V.; Webber, H.H.

    1984-01-01

    This book discusses both taxonomic and ecological topics on marine biology. Full coverage of marine organisms of all five kingdoms is provided, along with interesting and thorough discussion of all major marine habitats. Organization into six major parts allows flexibility. It also provides insight into important topics such as disposal of nuclear waste at sea, the idea that life began on the ocean floor, and how whales, krill, and people interact. A full-color photo chapter reviews questions, and exercises. The contents are: an overview marine biology: fundamental concepts/investigating life in the ocean; the physical ocean, the ocean floor, the nature of water, the nature and motion of ocean water; general ecology, conditions for life in the sea, biological productivity and energy transfer; marine organisms; monera, protista, mycota and metaphyta; the smaller marine animals, the large animals marine habitats, the intertidal zone/benthos of the continental shelf, the photic zone, the deep ocean, the ocean under stress, marine pollution, appendix a: the metric system and conversion factors/ appendix b: prefixes and suffixes/ appendix c: taxonomic classification of common marine organisms, and glossary, and index

  16. Balance of the West Antarctic Ice Sheet

    Science.gov (United States)

    2002-01-01

    For several decades, measurements of the West Antarctic Ice Sheet showed it to be retreating rapidly. But new data derived from satellite-borne radar sensors show the ice sheet to be growing. Changing Antarctic ice sheets remains an area of high scientific interest, particularly in light of recent global warming concerns. These new findings are significant because scientists estimate that sea level would rise 5-6 meters (16-20 feet) if the ice sheet collapsed into the sea. Do these new measurements signal the end of the ice sheet's 10,000-year retreat? Or, are these new satellite data simply much more accurate than the sparse ice core and surface measurements that produced the previous estimates? Another possibility is that the ice accumulation may simply indicate that the ice sheet naturally expands and retreats in regular cycles. Cryologists will grapple with these questions, and many others, as they examine the new data. The image above depicts the region of West Antarctica where scientists measured ice speed. The fast-moving central ice streams are shown in red. Slower tributaries feeding the ice streams are shown in blue. Green areas depict slow-moving, stable areas. Thick black lines depict the areas that collect snowfall to feed their respective ice streams. Reference: Ian Joughin and Slawek Tulaczyk Science Jan 18 2002: 476-480. Image courtesy RADARSAT Antarctic Mapping Project

  17. Antarctic isolation: immune and viral studies

    Science.gov (United States)

    Tingate, T. R.; Lugg, D. J.; Muller, H. K.; Stowe, R. P.; Pierson, D. L.

    1997-01-01

    Stressful environmental conditions are a major determinant of immune reactivity. This effect is pronounced in Australian National Antarctic Research Expedition populations exposed to prolonged periods of isolation in the Antarctic. Alterations of T cell function, including depression of cutaneous delayed-type hypersensitivity responses and a peak 48.9% reduction of T cell proliferation to the mitogen phytohaemagglutinin, were documented during a 9-month period of isolation. T cell dysfunction was mediated by changes within the peripheral blood mononuclear cell compartment, including a paradoxical atypical monocytosis associated with altered production of inflammatory cytokines. There was a striking reduction in the production by peripheral blood mononuclear cells of the predominant pro-inflammatory monokine TNF-alpha and changes were also detected in the production of IL-1, IL-2, IL-6, IL-1ra and IL-10. Prolonged Antarctic isolation is also associated with altered latent herpesvirus homeostasis, including increased herpesvirus shedding and expansion of the polyclonal latent Epstein-Barr virus-infected B cell population. These findings have important long-term health implications.

  18. EVA: Evryscopes for the Arctic and Antarctic

    Science.gov (United States)

    Richichi, A.; Law, N.; Tasuya, O.; Fors, O.; Dennihy, E.; Carlberg, R.; Tuthill, P.; Ashley, M.; Soonthornthum, B.

    2017-06-01

    We are planning to build Evryscopes for the Arctic and Antarctic (EVA), which will enable the first ultra-wide-field, high-cadence sky survey to be conducted from both Poles. The system is based on the successful Evryscope concept, already installed and operating since 2015 at Cerro Tololo in Chile with the following characteristics: robotic operation, 8,000 square degrees simultaneous sky coverage, 2-minute cadence, milli-mag level photometric accuracy, pipelined data processing for real-time analysis and full data storage for off-line analysis. The initial location proposed for EVA is the PEARL station on Ellesmere island; later also an antarctic location shall be selected. The science goals enabled by this unique combination of almost full-sky coverage and high temporal cadence are numerous, and include among others ground-breaking forays in the fields of exoplanets, stellar variability, asteroseismology, supernovae and other transient events. The EVA polar locations will enable uninterrupted observations lasting in principle over weeks and months. EVA will be fully robotic. We discuss the EVA science drivers and expected results, and present the logistics and the outline of the project which is expected to have first light in the winter of 2018. The cost envelope can be kept very competitive thanks to R&D already employed for the CTIO Evryscope, to our experience with both Arctic and Antarctic locations, and to the use of off-the-shelf components.

  19. Extraction and characterization of collagen from Antarctic and Sub-Antarctic squid and its potential application in hybrid scaffolds for tissue engineering.

    Science.gov (United States)

    Coelho, Rui C G; Marques, Ana L P; Oliveira, Sara M; Diogo, Gabriela S; Pirraco, Rogério P; Moreira-Silva, Joana; Xavier, José C; Reis, Rui L; Silva, Tiago H; Mano, João F

    2017-09-01

    Collagen is the most abundant protein found in mammals and it exhibits a low immunogenicity, high biocompatibility and biodegradability when compared with others natural polymers. For this reason, it has been explored for the development of biologically instructive biomaterials with applications for tissue substitution and regeneration. Marine origin collagen has been pursued as an alternative to the more common bovine and porcine origins. This study focused on squid (Teuthoidea: Cephalopoda), particularly the Antarctic squid Kondakovia longimana and the Sub-Antarctic squid Illex argentinus as potential collagen sources. In this study, collagen has been isolated from the skins of the squids using acid-based and pepsin-based protocols, with the higher yield being obtained from I. argentinus in the presence of pepsin. The produced collagen has been characterized in terms of physicochemical properties, evidencing an amino acid profile similar to the one of calf collagen, but exhibiting a less preserved structure, with hydrolyzed portions and a lower melting temperature. Pepsin-soluble collagen isolated from I. argentinus was selected for further evaluation of biomedical potential, exploring its incorporation on poly-ε-caprolactone (PCL) 3D printed scaffolds for the development of hybrid scaffolds for tissue engineering, exhibiting hierarchical features. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Global Priorities for Marine Biodiversity Conservation

    Science.gov (United States)

    Selig, Elizabeth R.; Turner, Will R.; Troëng, Sebastian; Wallace, Bryan P.; Halpern, Benjamin S.; Kaschner, Kristin; Lascelles, Ben G.; Carpenter, Kent E.; Mittermeier, Russell A.

    2014-01-01

    In recent decades, many marine populations have experienced major declines in abundance, but we still know little about where management interventions may help protect the highest levels of marine biodiversity. We used modeled spatial distribution data for nearly 12,500 species to quantify global patterns of species richness and two measures of endemism. By combining these data with spatial information on cumulative human impacts, we identified priority areas where marine biodiversity is most and least impacted by human activities, both within Exclusive Economic Zones (EEZs) and Areas Beyond National Jurisdiction (ABNJ). Our analyses highlighted places that are both accepted priorities for marine conservation like the Coral Triangle, as well as less well-known locations in the southwest Indian Ocean, western Pacific Ocean, Arctic and Antarctic Oceans, and within semi-enclosed seas like the Mediterranean and Baltic Seas. Within highly impacted priority areas, climate and fishing were the biggest stressors. Although new priorities may arise as we continue to improve marine species range datasets, results from this work are an essential first step in guiding limited resources to regions where investment could best sustain marine biodiversity. PMID:24416151

  1. Global priorities for marine biodiversity conservation.

    Directory of Open Access Journals (Sweden)

    Elizabeth R Selig

    Full Text Available In recent decades, many marine populations have experienced major declines in abundance, but we still know little about where management interventions may help protect the highest levels of marine biodiversity. We used modeled spatial distribution data for nearly 12,500 species to quantify global patterns of species richness and two measures of endemism. By combining these data with spatial information on cumulative human impacts, we identified priority areas where marine biodiversity is most and least impacted by human activities, both within Exclusive Economic Zones (EEZs and Areas Beyond National Jurisdiction (ABNJ. Our analyses highlighted places that are both accepted priorities for marine conservation like the Coral Triangle, as well as less well-known locations in the southwest Indian Ocean, western Pacific Ocean, Arctic and Antarctic Oceans, and within semi-enclosed seas like the Mediterranean and Baltic Seas. Within highly impacted priority areas, climate and fishing were the biggest stressors. Although new priorities may arise as we continue to improve marine species range datasets, results from this work are an essential first step in guiding limited resources to regions where investment could best sustain marine biodiversity.

  2. Draft genome of the Antarctic dragonfish, Parachaenichthys charcoti.

    Science.gov (United States)

    Ahn, Do-Hwan; Shin, Seung Chul; Kim, Bo-Mi; Kang, Seunghyun; Kim, Jin-Hyoung; Ahn, Inhye; Park, Joonho; Park, Hyun

    2017-08-01

    The Antarctic bathydraconid dragonfish, Parachaenichthys charcoti, is an Antarctic notothenioid teleost endemic to the Southern Ocean. The Southern Ocean has cooled to -1.8ºC over the past 30 million years, and the seawater had retained this cold temperature and isolated oceanic environment because of the Antarctic Circumpolar Current. Notothenioids dominate Antarctic fish, making up 90% of the biomass, and all notothenioids have undergone molecular and ecological diversification to survive in this cold environment. Therefore, they are considered an attractive Antarctic fish model for evolutionary and ancestral genomic studies. Bathydraconidae is a speciose family of the Notothenioidei, the dominant taxonomic component of Antarctic teleosts. To understand the process of evolution of Antarctic fish, we select a typical Antarctic bathydraconid dragonfish, P. charcoti. Here, we have sequenced, de novo assembled, and annotated a comprehensive genome from P. charcoti. The draft genome of P. charcoti is 709 Mb in size. The N50 contig length is 6145 bp, and its N50 scaffold length 178 362 kb. The genome of P. charcoti is predicted to contain 32 712 genes, 18 455 of which have been assigned preliminary functions. A total of 8951 orthologous groups common to 7 species of fish were identified, while 333 genes were identified in P. charcoti only; 2519 orthologous groups were also identified in both P. charcoti and N. coriiceps, another Antarctic fish. Four gene ontology terms were statistically overrepresented among the 333 genes unique to P. charcoti, according to gene ontology enrichment analysis. The draft P. charcoti genome will broaden our understanding of the evolution of Antarctic fish in their extreme environment. It will provide a basis for further investigating the unusual characteristics of Antarctic fishes. © The Author 2017. Published by Oxford University Press.

  3. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high ... or by any means without permission in writing from the copyright holder. ..... Journal of Chemical Engineering Research and Design 82 ... Indian Ocean Marine Science Association Technical.

  4. Marine Biomedicine

    Science.gov (United States)

    Bang, Frederik B.

    1977-01-01

    Describes early scientific research involving marine invertebrate pathologic processes that may have led to new insights into human disease. Discussed are inquiries of Metchnikoff, Loeb, and Cantacuzene (immunolgic responses in sea stars, horseshoe crabs, and marine worms, respectively). Describes current research stemming from these early…

  5. Marine Biology

    Science.gov (United States)

    Dewees, Christopher M.; Hooper, Jon K.

    1976-01-01

    A variety of informational material for a course in marine biology or oceanology at the secondary level is presented. Among the topics discussed are: food webs and pyramids, planktonic blooms, marine life, plankton nets, food chains, phytoplankton, zooplankton, larval plankton and filter feeders. (BT)

  6. Initiation and long-term instability of the East Antarctic Ice Sheet.

    Science.gov (United States)

    Gulick, Sean P S; Shevenell, Amelia E; Montelli, Aleksandr; Fernandez, Rodrigo; Smith, Catherine; Warny, Sophie; Bohaty, Steven M; Sjunneskog, Charlotte; Leventer, Amy; Frederick, Bruce; Blankenship, Donald D

    2017-12-13

    Antarctica's continental-scale ice sheets have evolved over the past 50 million years. However, the dearth of ice-proximal geological records limits our understanding of past East Antarctic Ice Sheet (EAIS) behaviour and thus our ability to evaluate its response to ongoing environmental change. The EAIS is marine-terminating and grounded below sea level within the Aurora subglacial basin, indicating that this catchment, which drains ice to the Sabrina Coast, may be sensitive to climate perturbations. Here we show, using marine geological and geophysical data from the continental shelf seaward of the Aurora subglacial basin, that marine-terminating glaciers existed at the Sabrina Coast by the early to middle Eocene epoch. This finding implies the existence of substantial ice volume in the Aurora subglacial basin before continental-scale ice sheets were established about 34 million years ago. Subsequently, ice advanced across and retreated from the Sabrina Coast continental shelf at least 11 times during the Oligocene and Miocene epochs. Tunnel valleys associated with half of these glaciations indicate that a surface-meltwater-rich sub-polar glacial system existed under climate conditions similar to those anticipated with continued anthropogenic warming. Cooling since the late Miocene resulted in an expanded polar EAIS and a limited glacial response to Pliocene warmth in the Aurora subglacial basin catchment. Geological records from the Sabrina Coast shelf indicate that, in addition to ocean temperature, atmospheric temperature and surface-derived meltwater influenced East Antarctic ice mass balance under warmer-than-present climate conditions. Our results imply a dynamic EAIS response with continued anthropogenic warming and suggest that the EAIS contribution to future global sea-level projections may be under-estimated.

  7. 77 FR 5403 - Conservation of Antarctic Animals and Plants

    Science.gov (United States)

    2012-02-03

    ... NATIONAL SCIENCE FOUNDATION 45 CFR Part 670 Conservation of Antarctic Animals and Plants AGENCY: National Science Foundation. ACTION: Final rule. SUMMARY: Pursuant to the Antarctic Conservation Act of 1978, The National Science Foundation (NSF) is amending its regulations to reflect newly designated...

  8. Reaching for the Horizon: Enabling 21st Century Antarctic Science

    Science.gov (United States)

    Rogan-Finnemore, M.; Kennicutt, M. C., II; Kim, Y.

    2015-12-01

    The Council of Managers of National Antarctic Programs' (COMNAP) Antarctic Roadmap Challenges(ARC) project translated the 80 highest priority Antarctic and Southern Ocean scientific questionsidentified by the community via the SCAR Antarctic Science Horizon Scan into the highest prioritytechnological, access, infrastructure and logistics needs to enable the necessary research to answer thequestions. A workshop assembled expert and experienced Antarctic scientists and National AntarcticProgram operators from around the globe to discern the highest priority technological needs includingthe current status of development and availability, where the technologies will be utilized in the Antarctic area, at what temporal scales and frequencies the technologies will be employed,and how broadly applicable the technologies are for answering the highest priority scientific questions.Secondly the logistics, access, and infrastructure requirements were defined that are necessary todeliver the science in terms of feasibility including cost and benefit as determined by expected scientific return on investment. Finally, based on consideration of the science objectives and the mix oftechnologies implications for configuring National Antarctic Program logistics capabilities andinfrastructure architecture over the next 20 years were determined. In particular those elements thatwere either of a complexity, requiring long term investments to achieve and/or having an associated cost that realistically can only (or best) be achieved by international coordination, planning and partnerships were identified. Major trends (changes) in logistics, access, and infrastructure requirements were identified that allow for long-term strategic alignment of international capabilities, resources and capacity. The outcomes of this project will be reported.

  9. Biological studies in the Antarctic waters: A review

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.

    stream_size 12 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_407.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_407.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  10. Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years

    NARCIS (Netherlands)

    Gardner, Alex S.; Moholdt, Geir; Scambos, Ted; Fahnstock, Mark; Ligtenberg, Stefan; van den Broeke, Michiel; Nilsson, Johan

    2018-01-01

    Ice discharge from large ice sheets plays a direct role in determining rates of sea-level rise. We map present-day Antarctic-wide surface velocities using Landsat 7 and 8 imagery spanning 2013–2015 and compare to earlier estimates derived from synthetic aperture radar, revealing heterogeneous

  11. Antarctic biology in the 21st century - Advances in, and beyond the international polar year 2007-2008’

    Science.gov (United States)

    Stoddart, Michael

    2010-08-01

    The International Polar Year 2007-2008 (IPY) has provided an opportunity for biology to show itself as an important part of Antarctic science in a manner in which it was not seen during earlier Polar Years. Of the 15 endorsed biological projects in Antarctica, 7 included more than 20 scientists and could be deemed truly international. Four were conducted in the marine environment, and one each in the fields of biological invasions, microbial ecology, and terrestrial ecology, and one was SCAR’s over-arching ‘Evolution and Biodiversity in the Antarctic’. The marine projects have left a robust legacy of data for future research into the consequences of environmental change, and into future decisions about marine protected areas. Studies on introductions of exotic organisms reveal an ever-present threat to the warmer parts of the high-latitude Southern Ocean, or parts which might become warmer with climate change. Studies on microbial ecology reveal great complexity of ecosystems with high numbers of unknown species. Terrestrial research has shown how vulnerable the Antarctic is to accidental introductions, and how productive the soils can be under changed climate conditions. Antarctic biology has come-of-age during IPY 2007-2008 and the campaign has set the scene for future research.

  12. Natural products mediating ecological interactions in Antarctic benthic communities: a mini-review of the known molecules.

    Science.gov (United States)

    Núñez-Pons, L; Avila, C

    2015-07-01

    Out of the many bioactive compounds described from the oceans, only a small fraction have been studied for their ecological significance. Similarly, most chemically mediated interactions are not well understood, because the molecules involved remain unrevealed. In Antarctica, this gap in knowledge is even more acute in comparison to tropical or temperate regions, even though polar organisms are also prolific producers of chemical defenses, and pharmacologically relevant products are being reported from the Southern Ocean. The extreme and unique marine environments surrounding Antarctica along with the numerous unusual interactions taking place in benthic communities are expected to select for novel functional secondary metabolites. There is an urgent need to comprehend the evolutionary role of marine derived substances in general, and particularly at the Poles, since molecules of keystone significance are vital in species survival, and therefore, in structuring the communities. Here we provide a mini-review on the identified marine natural products proven to have an ecological function in Antarctic ecosystems. This report recapitulates some of the bibliography from original Antarctic reviews, and updates the new literature in the field from 2009 to the present.

  13. Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years

    Science.gov (United States)

    Gardner, Alex S.; Moholdt, Geir; Scambos, Ted; Fahnstock, Mark; Ligtenberg, Stefan; van den Broeke, Michiel; Nilsson, Johan

    2018-02-01

    Ice discharge from large ice sheets plays a direct role in determining rates of sea-level rise. We map present-day Antarctic-wide surface velocities using Landsat 7 and 8 imagery spanning 2013-2015 and compare to earlier estimates derived from synthetic aperture radar, revealing heterogeneous changes in ice flow since ˜ 2008. The new mapping provides complete coastal and inland coverage of ice velocity north of 82.4° S with a mean error of image pairs acquired during the daylight period. Using an optimized flux gate, ice discharge from Antarctica is 1929 ± 40 Gigatons per year (Gt yr-1) in 2015, an increase of 36 ± 15 Gt yr-1 from the time of the radar mapping. Flow accelerations across the grounding lines of West Antarctica's Amundsen Sea Embayment, Getz Ice Shelf and Marguerite Bay on the western Antarctic Peninsula, account for 88 % of this increase. In contrast, glaciers draining the East Antarctic Ice Sheet have been remarkably constant over the period of observation. Including modeled rates of snow accumulation and basal melt, the Antarctic ice sheet lost ice at an average rate of 183 ± 94 Gt yr-1 between 2008 and 2015. The modest increase in ice discharge over the past 7 years is contrasted by high rates of ice sheet mass loss and distinct spatial patters of elevation lowering. The West Antarctic Ice Sheet is experiencing high rates of mass loss and displays distinct patterns of elevation lowering that point to a dynamic imbalance. We find modest increase in ice discharge over the past 7 years, which suggests that the recent pattern of mass loss in Antarctica is part of a longer-term phase of enhanced glacier flow initiated in the decades leading up to the first continent-wide radar mapping of ice flow.

  14. Parameter Estimations of Dynamic Energy Budget (DEB Model over the Life History of a Key Antarctic Species: The Antarctic Sea Star Odontaster validus Koehler, 1906.

    Directory of Open Access Journals (Sweden)

    Antonio Agüera

    Full Text Available Marine organisms in Antarctica are adapted to an extreme ecosystem including extremely stable temperatures and strong seasonality due to changes in day length. It is now largely accepted that Southern Ocean organisms are particularly vulnerable to global warming with some regions already being challenged by a rapid increase of temperature. Climate change affects both the physical and biotic components of marine ecosystems and will have an impact on the distribution and population dynamics of Antarctic marine organisms. To predict and assess the effect of climate change on marine ecosystems a more comprehensive knowledge of the life history and physiology of key species is urgently needed. In this study we estimate the Dynamic Energy Budget (DEB model parameters for key benthic Antarctic species the sea star Odontaster validus using available information from literature and experiments. The DEB theory is unique in capturing the metabolic processes of an organism through its entire life cycle as a function of temperature and food availability. The DEB model allows for the inclusion of the different life history stages, and thus, becomes a tool that can be used to model lifetime feeding, growth, reproduction, and their responses to changes in biotic and abiotic conditions. The DEB model presented here includes the estimation of reproduction handling rules for the development of simultaneous oocyte cohorts within the gonad. Additionally it links the DEB model reserves to the pyloric caeca an organ whose function has long been ascribed to energy storage. Model parameters described a slowed down metabolism of long living animals that mature slowly. O. validus has a large reserve that-matching low maintenance costs- allow withstanding long periods of starvation. Gonad development is continuous and individual cohorts developed within the gonads grow in biomass following a power function of the age of the cohort. The DEB model developed here for O

  15. Emerging spatial patterns in Antarctic prokaryotes

    Directory of Open Access Journals (Sweden)

    Chun Wie eChong

    2015-09-01

    Full Text Available Recent advances in knowledge of patterns of biogeography in terrestrial eukaryotic organisms have led to a fundamental paradigm shift in understanding of the controls and history of life on land in Antarctica, and its interactions over the long term with the glaciological and geological processes that have shaped the continent. However, while it has long been recognized that the terrestrial ecosystems of Antarctica are dominated by microbes and their processes, knowledge of microbial diversity and distributions has lagged far behind that of the macroscopic eukaryote organisms. Increasing human contact with and activity in the continent is leading to risks of biological contamination and change in a region whose isolation has protected it for millions of years at least; these risks may be particularly acute for microbial communities which have, as yet, received scant recognition and attention. Even a matter apparently as straightforward as Protected Area designation in Antarctica requires robust biodiversity data which, in most parts of the continent, remain almost completely unavailable. A range of important contributing factors mean that it is now timely to reconsider the state of knowledge of Antarctic terrestrial prokaryotes. Rapid advances in molecular biological approaches are increasingly demonstrating that bacterial diversity in Antarctica may be far greater than previously thought, and that there is overlap in the environmental controls affecting both Antarctic prokaryotic and eukaryotic communities. Bacterial dispersal mechanisms and colonization patterns remain largely unaddressed, although evidence for regional evolutionary differentiation is rapidly accruing and, with this, there is increasing appreciation of patterns in regional bacterial biogeography in this large part of the globe. In this review, we set out to describe the state of knowledge of Antarctic prokaryote diversity patterns, drawing analogy with those of eukaryote

  16. Automatic focusing system of BSST in Antarctic

    Science.gov (United States)

    Tang, Peng-Yi; Liu, Jia-Jing; Zhang, Guang-yu; Wang, Jian

    2015-10-01

    Automatic focusing (AF) technology plays an important role in modern astronomical telescopes. Based on the focusing requirement of BSST (Bright Star Survey Telescope) in Antarctic, an AF system is set up. In this design, functions in OpenCV is used to find stars, the algorithm of area, HFD or FWHM are used to degree the focus metric by choosing. Curve fitting method is used to find focus position as the method of camera moving. All these design are suitable for unattended small telescope.

  17. Antarctic Lithosphere Studies: Progress, Problems and Promise

    Science.gov (United States)

    Dalziel, I. W. D.; Wilson, T. J.

    2017-12-01

    In the sixty years since the International Geophysical Year, studies of the Antarctic lithosphere have progressed from basic geological observations and sparse geophysical measurements to continental-scale datasets of radiometric dates, ice thickness, bedrock topography and characteristics, seismic imaging and potential fields. These have been augmented by data from increasingly dense broadband seismic and geodetic networks. The Antarctic lithosphere is known to have been an integral part, indeed a "keystone" of the Pangea ( 250-185Ma) and Gondwanaland ( 540-180 Ma) supercontinents. It is widely believed to have been part of hypothetical earlier supercontinents Rodinia ( 1.0-0.75 Ga) and Columbia (Nuna) ( 2.0-1.5 Ga). Despite the paucity of exposure in East Antarctica, the new potential field datasets have emboldened workers to extrapolate Precambrian geological provinces and structures from neighboring continents into Antarctica. Hence models of the configuration of Columbia and its evolution into Rodinia and Gondwana have been proposed, and rift-flank uplift superimposed on a Proterozoic orogenic root has been hypothesized to explain the Gamburtsev Subglacial Mountains. Mesozoic-Cenozoic rifting has imparted a strong imprint on the West Antarctic lithosphere. Seismic tomographic evidence reveals lateral variation in lithospheric thickness, with the thinnest zones within the West Antarctic rift system and underlying the Amundsen Sea Embayment. Upper mantle low velocity zones are extensive, with a deeper mantle velocity anomaly underlying Marie Byrd Land marking a possible mantle plume. Misfits between crustal motions measured by GPS and GIA model predictions can, in part, be linked with the changes in lithosphere thickness and mantle rheology. Unusually high uplift rates measured by GPS in the Amundsen region can be interpreted as the response of regions with thin lithosphere and weak mantle to late Holocene ice mass loss. Horizontal displacements across the TAM

  18. Terrestrial and exposure histories of Antarctic meteorites

    International Nuclear Information System (INIS)

    Nishiizumi, K.

    1986-01-01

    Records of cosmogenic effects were studied in a large suite of Antarctic meteorites. The cosmogenic nuclide measurements together with cosmic ray track measurements on Antartic meteorites provide information such as exposure age, terrestrial age, size and depth in meteoroid or parent body, influx rate in the past, and pairing. The terrestrail age is the time period between the fall of the meteorite on the Earth and the present. To define terrestrial age, two or more nuclides with different half-lives and possibly noble gases are required. The cosmogenic radionuclides used are C-14, Kr-81, Cl-36, Al-26, Be-10, Mn-53, and K-40

  19. Terrestrial and exposure histories of Antarctic meteorites

    Science.gov (United States)

    Nishiizumi, K.

    1986-01-01

    Records of cosmogenic effects were studied in a large suite of Antarctic meteorites. The cosmogenic nuclide measurements together with cosmic ray track measurements on Antartic meteorites provide information such as exposure age, terrestrial age, size and depth in meteoroid or parent body, influx rate in the past, and pairing. The terrestrail age is the time period between the fall of the meteorite on the Earth and the present. To define terrestrial age, two or more nuclides with different half-lives and possibly noble gases are required. The cosmogenic radionuclides used are C-14, Kr-81, Cl-36, Al-26, Be-10, Mn-53, and K-40.

  20. Estimation of Antarctic Land-Fast Sea Ice Algal Biomass and Snow Thickness From Under-Ice Radiance Spectra in Two Contrasting Areas

    Science.gov (United States)

    Wongpan, P.; Meiners, K. M.; Langhorne, P. J.; Heil, P.; Smith, I. J.; Leonard, G. H.; Massom, R. A.; Clementson, L. A.; Haskell, T. G.

    2018-03-01

    Fast ice is an important component of Antarctic coastal marine ecosystems, providing a prolific habitat for ice algal communities. This work examines the relationships between normalized difference indices (NDI) calculated from under-ice radiance measurements and sea ice algal biomass and snow thickness for Antarctic fast ice. While this technique has been calibrated to assess biomass in Arctic fast ice and pack ice, as well as Antarctic pack ice, relationships are currently lacking for Antarctic fast ice characterized by bottom ice algae communities with high algal biomass. We analyze measurements along transects at two contrasting Antarctic fast ice sites in terms of platelet ice presence: near and distant from an ice shelf, i.e., in McMurdo Sound and off Davis Station, respectively. Snow and ice thickness, and ice salinity and temperature measurements support our paired in situ optical and biological measurements. Analyses show that NDI wavelength pairs near the first chlorophyll a (chl a) absorption peak (≈440 nm) explain up to 70% of the total variability in algal biomass. Eighty-eight percent of snow thickness variability is explained using an NDI with a wavelength pair of 648 and 567 nm. Accounting for pigment packaging effects by including the ratio of chl a-specific absorption coefficients improved the NDI-based algal biomass estimation only slightly. Our new observation-based algorithms can be used to estimate Antarctic fast ice algal biomass and snow thickness noninvasively, for example, by using moored sensors (time series) or mapping their spatial distributions using underwater vehicles.

  1. Cloacal evaporative cooling: a previously undescribed means of increasing evaporative water loss at higher temperatures in a desert ectotherm, the Gila monster Heloderma suspectum.

    Science.gov (United States)

    DeNardo, Dale F; Zubal, Tricia E; Hoffman, Ty C M

    2004-02-01

    The Gila monster Heloderma suspectum is an active forager in an environment that, at times, can be extremely hot and arid. Thus, Gila monsters face extreme thermostatic and hydrostatic demands. For a desert ectotherm routinely risking dehydration, evaporative water loss (EWL) is typically viewed as detrimental. Yet evaporation simultaneously dehydrates and cools an animal. We explored EWL in Gila monsters by measuring cutaneous, ventilatory and cloacal EWL at five ambient temperatures between 20.5 degrees C and 40 degrees C. Our results show that Gila monsters have high EWL rates relative to body mass. Cutaneous EWL underwent a consistent, temperature-dependent increase over the entire range of test temperatures (Q(10)=1.61, with EWL ranging from 0.378 to 0.954 mg g(-1) h(-1)). Ventilatory EWL did not show a significant temperature-dependent response, but ranged from 0.304 to 0.663 mg g(-1) h(-1). Cloacal EWL was extremely low and relatively constant between 20.5 degrees C and 35 degrees C, but rose dramatically above 35 degrees C (Q(10) >8.3 x 10(7), from 0.0008 at 35 degrees C to 7.30 mg g(-1) h(-1) at 40 degrees C). This steep rise in cloacal EWL coincided with an increasing suppression of body temperature relative to ambient temperature. Dehydration to 80% of initial body mass led to a delay in the onset and an attenuation of the dramatic increase in cloacal EWL. These results emphasize the potential value of EWL for thermoregulation in ectotherms and demonstrate for the first time the role of the cloaca in this process.

  2. Post-hatching development of mitochondrial function, organ mass and metabolic rate in two ectotherms, the American alligator (Alligator mississippiensis and the common snapping turtle (Chelydra serpentina

    Directory of Open Access Journals (Sweden)

    Sarah K. G. Sirsat

    2016-04-01

    Full Text Available The ontogeny of endothermy in birds is associated with disproportionate growth of thermogenic organs and increased mitochondrial oxidative capacity. However, no similar study has been made of the development of these traits in ectotherms. For comparison, we therefore investigated the metabolism, growth and muscle mitochondrial function in hatchlings of a turtle and a crocodilian, two ectotherms that never develop endothermy. Metabolic rate did not increase substantially in either species by 30 days post-hatching. Yolk-free body mass and heart mass did not change through 30 days in alligators and heart mass was a constant proportion of body mass, even after 1 year. Yolk-free body mass and liver mass grew 36% and 27%, respectively, in turtles during the first 30 days post-hatch. The mass-specific oxidative phosphorylation capacity of mitochondria, assessed using permeabilized muscle fibers, increased by a non-significant 47% in alligator thigh and a non-significant 50% in turtle thigh over 30 days, but did not increase in the heart. This developmental trajectory of mitochondrial function is slower and shallower than that previously observed in ducks, which demonstrate a 90% increase in mass-specific oxidative phosphorylation capacity in thigh muscles over just a few days, a 60% increase in mass-specific oxidative phosphorylation capacity of the heart over a few days, and disproportionate growth of the heart and other organs. Our data thus support the hypothesis that these developmental changes in ducks represent mechanistic drivers for attaining endothermy.

  3. Post-hatching development of mitochondrial function, organ mass and metabolic rate in two ectotherms, the American alligator (Alligator mississippiensis) and the common snapping turtle (Chelydra serpentina).

    Science.gov (United States)

    Sirsat, Sarah K G; Sirsat, Tushar S; Price, Edwin R; Dzialowski, Edward M

    2016-04-15

    The ontogeny of endothermy in birds is associated with disproportionate growth of thermogenic organs and increased mitochondrial oxidative capacity. However, no similar study has been made of the development of these traits in ectotherms. For comparison, we therefore investigated the metabolism, growth and muscle mitochondrial function in hatchlings of a turtle and a crocodilian, two ectotherms that never develop endothermy. Metabolic rate did not increase substantially in either species by 30 days post-hatching. Yolk-free body mass and heart mass did not change through 30 days in alligators and heart mass was a constant proportion of body mass, even after 1 year. Yolk-free body mass and liver mass grew 36% and 27%, respectively, in turtles during the first 30 days post-hatch. The mass-specific oxidative phosphorylation capacity of mitochondria, assessed using permeabilized muscle fibers, increased by a non-significant 47% in alligator thigh and a non-significant 50% in turtle thigh over 30 days, but did not increase in the heart. This developmental trajectory of mitochondrial function is slower and shallower than that previously observed in ducks, which demonstrate a 90% increase in mass-specific oxidative phosphorylation capacity in thigh muscles over just a few days, a 60% increase in mass-specific oxidative phosphorylation capacity of the heart over a few days, and disproportionate growth of the heart and other organs. Our data thus support the hypothesis that these developmental changes in ducks represent mechanistic drivers for attaining endothermy. © 2016. Published by The Company of Biologists Ltd.

  4. Marine Science

    African Journals Online (AJOL)

    between humans and the coastal and marine environment. ... The journal has a new and more modern layout, published online only, and the editorial .... the population structure of Platorchestia fayetta sp. nov. and their interaction with the.

  5. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the ... tidal height and amplitude can influence light penetra- ...... to environmental parameters in cage culture area of Sepanggar Bay, Malaysia.

  6. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ... consist of special issues on major events or important thematic issues. ... of sources, including plant and animal by- products.

  7. Marine biotoxins

    National Research Council Canada - National Science Library

    2004-01-01

    ... (ciguatera fish poisoning). It discusses in detail the causative toxins produced by marine organisms, chemical structures and analytical methods, habitat and occurrence of the toxin-producing organisms, case studies and existing regulations...

  8. Marine Science

    African Journals Online (AJOL)

    pod diversity and distribution are important especially since studies on marine biodiversity are scarce .... Method II –. Zamoum &. Furla (2012) protocol. Method III. – Geist et al (2008) protocol ..... Public Library Of Science One 8: 51273.

  9. Marine pollution

    International Nuclear Information System (INIS)

    Clark, R.B.

    1992-01-01

    The effects of petroleum, waste materials, halogenated hydrocarbons, radioactivity and heat on the marine ecosystem, the fishing industry and human health are discussed using the example of the North Sea. (orig.) [de

  10. Marine Science

    African Journals Online (AJOL)

    No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form ... to optimize nucleic acid extraction protocols from marine gastropods, present an ...... Greenfield., Gomez E, Harvell CD, Sale PF, Edwards.

  11. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high ..... circulation patterns include the nutrient-rich Somali ...... matical Structures in Computer Science 24: e240311.

  12. Marine insects

    National Research Council Canada - National Science Library

    Cheng, Lanna

    1976-01-01

    .... Not only are true insects, such as the Collembola and insect parasites of marine birds and mammals, considered, but also other kinds of intertidal air-breathing arthropods, notably spiders, scorpions...

  13. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue .... shell growth is adversely affected. ... local stressors in action, such as ocean acidification ..... that the distribution of many intertidal sessile animals.

  14. Penguin Proxies: Deciphering Millennial-Scale Antarctic Ecosystem Change using Amino Acid Stable Isotope Analysis.

    Science.gov (United States)

    Michelson, C.; McMahon, K.; Emslie, S. D.; Patterson, W. P.; McCarthy, M. D.; Polito, M. J.

    2017-12-01

    The Southern Ocean ecosystem is undergoing rapid environmental change due to ongoing and historic anthropogenic impacts such as climate change and marine mammal harvesting. These disturbances may have cascading effects through the Antarctic food webs, resulting in profound shifts in the sources and cycling of organic matter supporting higher-trophic organisms, such as penguins. For example, bulk stable isotope analyses of modern and ancient preserved penguin tissues suggest variations in penguin feeding ecology throughout the Holocene with dramatic isotopic shifts in the last 200 years. However, it is not clear whether these isotopic shifts resulted from changes at the base of the food web, dietary shifts in penguins, or some combination of both factors. Newly developed compound-specific stable nitrogen isotope analysis of individual amino acids (CSIA-AA) may provide a powerful new tool to tease apart these confounding variables. Stable nitrogen isotope values of trophic amino acids (e.g., glutamic acid) increase substantially with each trophic transfer in the food web, while source amino acid (e.g., phenylalanine) stable nitrogen isotope values remain relatively unchanged and reflect ecosystem baselines. As such, we can use this CSIA-AA approach to decipher between baseline and dietary shifts in penguins over time from modern and ancient eggshells of Pygoscelis penguins in the Antarctic Peninsula and the Ross Sea regions of Antarctica. In order to accurately apply this CSIA-AA approach, we first characterized the trophic fractionation factors of individual amino acids between diet and penguin consumers in a long-term controlled penguin feeding experiment. We then applied these values to modern and ancient eggshells from the Antarctic Peninsula and Ross Sea to evaluate shifts in penguin trophic dynamics as a function of climate and anthropogenic interaction throughout much of the Holocene. This work develops a cutting edge new molecular geochemistry approach

  15. What's Cooler Than Being Cool? Icefin: Robotic Exploration Beneath Antarctic Ice Shelves

    Science.gov (United States)

    Lawrence, J.; Schmidt, B. E.; Meister, M. R.; Glass, J. B.; Bowman, J. S.; Stockton, A. M.; Dichek, D.; Hurwitz, B.; Ramey, C.; Spears, A.; Walker, C. C.

    2017-12-01

    The 2017-18 Antarctic field season marks the first of three under the RISEUP project (Ross Ice Shelf & Europa Underwater Probe, NASA PSTAR program grant NNX16AL07G, PI B. E. Schmidt). RISEUP expands our efforts to understand the physical processes governing ice-ocean interactions from beneath the McMurdo Ice Shelf (MIS) to the Ross Ice Shelf (RIS), utilizing the modular autonomous or remotely operable submersible vehicle (AUV/ROV) Icefin. The remote, aphotic regions below Antarctic shelves present a unique opportunity- they are both poorly understood terrestrial environments and analogs for similar systems hypothesized to be present on other bodies in our solar system, such as Europa and Enceladus. By developing new robotic technologies to access and explore ice shelf cavities we are advancing our understanding of how temperature, pressure, and salinity influence the ice-ocean interface, the limits of habitable environments on Earth, and what biological processes and adaptations enable the life discovered by the RISP and WISSARD programs during initial exploration beneath the RIS. These investigations further our understanding of ocean world habitability and support planned and proposed planetary missions (e.g. Europa Clipper, Europa Lander) via improved constraint of marine ice accretion processes, organic entrainment, and interface habitability. Custom built at Georgia Tech and first deployed during the 2014/15 Antarctic season, Icefin is 3.5 m, 125 kg modular vehicle that now carries a full suite of oceanographic sensors (including conductivity, temperature, depth, dissolved O2, dissolved organic matter, turbidity, pH, eH, and sonar) that can be deployed through boreholes as small as 25 cm in diameter. Here we present continued analysis of basal ice and oceanographic observations in the McMurdo Sound region from 2012-2015 with, pending anticipated field work, comparisons to preliminary data from the 2017/18 field season beneath both the McMurdo and Ross Ice

  16. Antarctic Starfish (Echinodermata, Asteroidea) from the ANDEEP3 expedition.

    Science.gov (United States)

    Danis, Bruno; Jangoux, Michel; Wilmes, Jennifer

    2012-01-01

    species, newly reported in the Southern Ocean.The quality of the data was controlled very thoroughly, by means of on-board Polarstern GPS systems, checking of identification by a renowned specialist (Prof. Michel Jangoux, Université Libre de Bruxelles), and matching to the Register of Antarctic Marine Species (RAMS) and World Register of Marine Species (WoRMS). The data is therefore fit for completing checklists, for inclusion in biodiversity patterns analysis, or niche modeling. It also nicely fills an information gap regarding deep-sea starfish from the Southern Ocean, for which data is very scarce at this time. The authors may be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies.

  17. Environmental Variation and Cohort Effects in an Antarctic Predator

    Science.gov (United States)

    Garrott, Robert A.; Rotella, Jay J.; Siniff, Donald B.; Parkinson, Claire L.; Stauffer, Glenn E.

    2011-01-01

    ice associated with climate change, suggest significant alterations in Antarctic marine ecosystems in the future.

  18. Icebergs, sea ice, blue carbon and Antarctic climate feedbacks.

    Science.gov (United States)

    Barnes, David K A; Fleming, Andrew; Sands, Chester J; Quartino, Maria Liliana; Deregibus, Dolores

    2018-06-28

    Sea ice, including icebergs, has a complex relationship with the carbon held within animals (blue carbon) in the polar regions. Sea-ice losses around West Antarctica's continental shelf generate longer phytoplankton blooms but also make it a hotspot for coastal iceberg disturbance. This matters because in polar regions ice scour limits blue carbon storage ecosystem services, which work as a powerful negative feedback on climate change (less sea ice increases phytoplankton blooms, benthic growth, seabed carbon and sequestration). This resets benthic biota succession (maintaining regional biodiversity) and also fertilizes the ocean with nutrients, generating phytoplankton blooms, which cascade carbon capture into seabed storage and burial by benthos. Small icebergs scour coastal shallows, whereas giant icebergs ground deeper, offshore. Significant benthic communities establish where ice shelves have disintegrated (giant icebergs calving), and rapidly grow to accumulate blue carbon storage. When 5000 km 2 giant icebergs calve, we estimate that they generate approximately 10 6 tonnes of immobilized zoobenthic carbon per year (t C yr -1 ). However, their collisions with the seabed crush and recycle vast benthic communities, costing an estimated 4 × 10 4  t C yr -1 We calculate that giant iceberg formation (ice shelf disintegration) has a net potential of approximately 10 6  t C yr -1 sequestration benefits as well as more widely known negative impacts.This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'. © 2018 The Authors.

  19. A pivotal role for ocean eddies in the distribution of microbial communities across the Antarctic Circumpolar Current.

    Directory of Open Access Journals (Sweden)

    Siddarthan Venkatachalam

    Full Text Available Mesoscale variability and associated eddy fluxes play crucial roles in ocean circulation dynamics and the ecology of the upper ocean. In doing so, these features are biologically important, providing a mechanism for the mixing and exchange of nutrients and biota within the ocean. Transient mesoscale eddies in the Southern Ocean are known to relocate zooplankton communities across the Antarctic Circumpolar Current (ACC and are important foraging grounds for marine top predators. In this study we investigated the role of cyclonic and anti-cyclonic eddies formed at the South-West Indian Ridge on the spatial variability and diversity of microbial communities. We focused on two contrasting adjacent eddies within the Antarctic Polar Frontal Zone to determine how these features may influence the microbial communities within this region. The water masses and microbiota of the two eddies, representative of a cyclonic cold core from the Antarctic zone and an anti-cyclonic warm-core from the Subantarctic zone, were compared. The data reveal that the two eddies entrain distinct microbial communities from their points of origin that are maintained for up to ten months. Our findings highlight the ecological impact that changes, brought by the translocation of eddies across the ACC, have on microbial diversity.

  20. Pan-Antarctic analysis aggregating spatial estimates of Adélie penguin abundance reveals robust dynamics despite stochastic noise.

    Science.gov (United States)

    Che-Castaldo, Christian; Jenouvrier, Stephanie; Youngflesh, Casey; Shoemaker, Kevin T; Humphries, Grant; McDowall, Philip; Landrum, Laura; Holland, Marika M; Li, Yun; Ji, Rubao; Lynch, Heather J

    2017-10-10

    Colonially-breeding seabirds have long served as indicator species for the health of the oceans on which they depend. Abundance and breeding data are repeatedly collected at fixed study sites in the hopes that changes in abundance and productivity may be useful for adaptive management of marine resources, but their suitability for this purpose is often unknown. To address this, we fit a Bayesian population dynamics model that includes process and observation error to all known Adélie penguin abundance data (1982-2015) in the Antarctic, covering >95% of their population globally. We find that process error exceeds observation error in this system, and that continent-wide "year effects" strongly influence population growth rates. Our findings have important implications for the use of Adélie penguins in Southern Ocean feedback management, and suggest that aggregating abundance across space provides the fastest reliable signal of true population change for species whose dynamics are driven by stochastic processes.Adélie penguins are a key Antarctic indicator species, but data patchiness has challenged efforts to link population dynamics to key drivers. Che-Castaldo et al. resolve this issue using a pan-Antarctic Bayesian model to infer missing data, and show that spatial aggregation leads to more robust inference regarding dynamics.

  1. Faunal diversity of the benthic amphipods (Crustacea of the Magellan region as compared to the Antarctic (preliminary results

    Directory of Open Access Journals (Sweden)

    Claude de Broyer

    1999-12-01

    Full Text Available To investigate the marine benthic ecosystems of the Magellan region and to compare them with the better known Antarctic systems, three campaigns were recently carried out in this area: the Joint Magellan Victor Hensen Campaign 1994, the Polarstern ANT XIII/4 cruise 1996, and the Vidal Gormaz CIMAR FIORDO II cruise 1996. Numerous and diverse zoobenthos samples were collected mostly with an Agassiz trawl and with a small dredge, an epibenthic sledge, with baited traps or by diving. All gears together gathered more than 132,000 specimens of gammaridean and caprellidean amphipods. 137 species of gammaridean amphipods have been identified from the material to date. About 20% of these species appear to be new for science. This taxonomic work takes place in the framework of a general revision of the Southern Ocean amphipod fauna undertaken by theAntarctic Amphipodologists Network. A complete list of the benthic species of gammaridean and caprellidean amphipods is presented, including the zoogeographical distribution and the new records. The new abundant material collected, still under study, will allow a comparison of faunal diversity, zoogeographical and ecological traits of the Magellan benthic amphipod taxocoenoses with those of the West and East Antarctic benthos.

  2. Mass balance of the Antarctic ice sheet.

    Science.gov (United States)

    Wingham, D J; Shepherd, A; Muir, A; Marshall, G J

    2006-07-15

    The Antarctic contribution to sea-level rise has long been uncertain. While regional variability in ice dynamics has been revealed, a picture of mass changes throughout the continental ice sheet is lacking. Here, we use satellite radar altimetry to measure the elevation change of 72% of the grounded ice sheet during the period 1992-2003. Depending on the density of the snow giving rise to the observed elevation fluctuations, the ice sheet mass trend falls in the range -5-+85Gtyr-1. We find that data from climate model reanalyses are not able to characterise the contemporary snowfall fluctuation with useful accuracy and our best estimate of the overall mass trend-growth of 27+/-29Gtyr-1-is based on an assessment of the expected snowfall variability. Mass gains from accumulating snow, particularly on the Antarctic Peninsula and within East Antarctica, exceed the ice dynamic mass loss from West Antarctica. The result exacerbates the difficulty of explaining twentieth century sea-level rise.

  3. When will the Antarctic Ozone Hole Recover?

    Science.gov (United States)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Steve

    2006-01-01

    The Antarctic ozone hole develops each year and culminates by early Spring. Antarctic ozone values have been monitored since 1979 using satellite observations from the .TOMS instrument. The severity of the hole has been assessed from TOMS using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average size during the September-October period. Ozone is mainly destroyed by halogen catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this presentation, we show the relationships of halogens and temperature to, both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. The ozone hole will begin to show first signs of recovery in about 2023, and the hole will fully recover to pre-1980 levels in approximately 2070. This 2070 recovery is 20 years later than recent projections.

  4. Metal complexation capacity of Antarctic lacustrine sediments.

    Science.gov (United States)

    Alberti, Giancarla; Mussi, Matteo; Quattrini, Federico; Pesavento, Maria; Biesuz, Raffaela

    2018-04-01

    The purpose of this study is to implement a work that is a part of a project funded by the Italian National Antarctic Research Program (PNRA, Piano Nazionale di Ricerche in Antartide) within the main thematic focus "Chemical Contamination-Global Change". This research was devoted to detect and characterize micro and nano components with strong complexing capability towards metal ions at trace level in sea water, lakes and lacustrine sediments, sampled during the XXII expedition of PNRA. In particular, in the present work, the sorption complexation capacity of an Antarctic lacustrine sediments toward Cu(II) and Pb(II) is described. The characterization of the sorption was undertaken, studying kinetics and isotherm profiles. The lake here considered is Tarn Flat in the area of Terra Nova Bay. The sorption equilibria of Cu(II) and Pb(II) on the lacustrine sediments were reached in about 10 h, and they were best modelled by the Langmuir equation. Preliminary, to establish if the data here obtained were consistent with those reported for the same area in other expeditions, a common multivariate techniques, namely the principal component analysis (PCA), was applied and finally the consistency of the data has been confirmed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Distribution and abundance of Antarctic krill (Euphausia superba) along the Antarctic Peninsula

    Science.gov (United States)

    Siegel, Volker; Reiss, Christian S.; Dietrich, Kimberly S.; Haraldsson, Matilda; Rohardt, Gerhard

    2013-07-01

    Net-based data on the abundance, distribution, and demographic patterns of Antarctic krill are quantified from a contemporaneous two ship survey of the Antarctic Peninsula during austral summer 2011. Two survey areas were sampled focussed on Marguerite Bay in the south, and the tip of the Antarctic Peninsula in the north. Data from 177 stations showed that the highest concentrations of krill were found in the southern sampling area. Differences between areas were associated with a few large catches of one year old krill found in anomalously warm and productive waters in Marguerite Bay, and small krill catches in the less-productive, offshore waters in the north. Estimated krill density across the survey area was 3.4 krill m-2, and was low compared to the long-term average of 45 krill m-2 for the Elephant Island area. Overall recruitment between the two survey regions was similar, but per capita recruitment was about 60% lower than historical mean recruitment levels measured at Elephant Island since the late 1970s. Demographic patterns showed small krill concentrated near the coast, and large krill concentrated offshore on the shelf and slope all along the survey area. The offshore distribution of adult krill was delineated by the warm (˜1 °C), low salinity (33.8) water at 30 m, suggesting that most krill were present shoreward of the southern boundary of Antarctic Circumpolar Current Front. Distributions of larvae indicated that three hotspot areas were important for the production of krill: slope areas outside Marguerite Bay and north of the South Shetland Islands, and near the coast around Antarctic Sound. Successful spawning, as inferred from larval abundance, was roughly coincident with the shelf break and not with inshore waters. Given the rapid changes in climate along the Antarctic Peninsula and the lower per capita recruitment observed in recent years, studies comparing and contrasting production, growth, and recruitment across the Peninsula will be

  6. Glacial removal of late Cenozoic subglacially emplaced volcanic edifices by the West Antarctic ice sheet

    Science.gov (United States)

    Behrendt, John C.; Blankenship, D.D.; Damaske, D.; Cooper, A. K.

    1995-01-01

    Local maxima of the horizontal gradient of pseudogravity from closely spaced aeromagnetic surveys over the Ross Sea, northwestern Ross Ice Shelf, and the West Antarctic ice sheet, reveal a linear magnetic rift fabric and numerous subcircular, high-amplitude anomalies. Geophysical data indicate two or three youthful volcanic edifices at widely separated areas beneath the sea and ice cover in the West Antarctic rift system. In contrast, we suggest glacial removal of edifices of volcanic sources of many more anomalies. Magnetic models, controlled by marine seismic reflection and radar ice-sounding data, allow us to infer that glacial removal of the associated late Cenozoic volcanic edifices (probably debris, comprising pillow breccias, and hyaloclastites) has occurred essentially concomitantly with their subglacial eruption. "Removal' of unconsolidated volcanic debris erupted beneath the ice is probably a more appropriate term than "erosion', given its fragmented, ice-contact origin. The exposed volcanoes may have been protected from erosion by the surrounding ice sheet because of more competent rock or high elevation above the ice sheet. -from Authors

  7. Recruitment, growth and mortality of an Antarctic hexactinellid sponge, Anoxycalyx joubini.

    Directory of Open Access Journals (Sweden)

    Paul K Dayton

    Full Text Available Polar ecosystems are sensitive to climate forcing, and we often lack baselines to evaluate changes. Here we report a nearly 50-year study in which a sudden shift in the population dynamics of an ecologically important, structure-forming hexactinellid sponge, Anoxycalyx joubini was observed. This is the largest Antarctic sponge, with individuals growing over two meters tall. In order to investigate life history characteristics of Antarctic marine invertebrates, artificial substrata were deployed at a number of sites in the southern portion of the Ross Sea between 1967 and 1975. Over a 22-year period, no growth or settlement was recorded for A. joubini on these substrata; however, in 2004 and 2010, A. joubini was observed to have settled and grown to large sizes on some but not all artificial substrata. This single settlement and growth event correlates with a region-wide shift in phytoplankton productivity driven by the calving of a massive iceberg. We also report almost complete mortality of large sponges followed over 40 years. Given our warming global climate, similar system-wide changes are expected in the future.

  8. Different Oceanographic Regimes in the Vicinity of the Antarctic Peninsula Reflected in Benthic Nematode Communities.

    Directory of Open Access Journals (Sweden)

    Freija Hauquier

    Full Text Available Marine free-living nematode communities were studied at similar depths (~500 m at two sides of the Antarctic Peninsula, characterised by different environmental and oceanographic conditions. At the Weddell Sea side, benthic communities are influenced by cold deep-water formation and seasonal sea-ice conditions, whereas the Drake Passage side experiences milder oceanic conditions and strong dynamics of the Antarctic Circumpolar Current. This resulted in different surface primary productivity, which contrasted with observed benthic pigment patterns and varied according to the area studied: chlorophyll a concentrations (as a proxy for primary production were high in the Weddell Sea sediments, but low in the surface waters above; this pattern was reversed in the Drake Passage. Differences between areas were largely mirrored by the nematode communities: nematode densities peaked in Weddell stations and showed deeper vertical occurrence in the sediment, associated with deeper penetration of chlorophyll a and indicative of a strong bentho-pelagic coupling. Generic composition showed some similarities across both areas, though differences in the relative contribution of certain genera were noted, together with distinct community shifts with depth in the sediment at all locations.

  9. Oxygen hypothesis of polar gigantism not supported by performance of Antarctic pycnogonids in hypoxia

    Science.gov (United States)

    Woods, H. Arthur; Moran, Amy L.; Arango, Claudia P.; Mullen, Lindy; Shields, Chris

    2008-01-01

    Compared to temperate and tropical relatives, some high-latitude marine species are large-bodied, a phenomenon known as polar gigantism. A leading hypothesis on the physiological basis of gigantism posits that, in polar water, high oxygen availability coupled to low metabolic rates relieves constraints on oxygen transport and allows the evolution of large body size. Here, we test the oxygen hypothesis using Antarctic pycnogonids, which have been evolving in very cold conditions (−1.8–0°C) for several million years and contain spectacular examples of gigantism. Pycnogonids from 12 species, spanning three orders of magnitude in body mass, were collected from McMurdo Sound, Antarctica. Individual sea spiders were forced into activity and their performance was measured at different experimental levels of dissolved oxygen (DO). The oxygen hypothesis predicts that, all else being equal, large pycnogonids should perform disproportionately poorly in hypoxia, an outcome that would appear as a statistically significant interaction between body size and oxygen level. In fact, although we found large effects of DO on performance, and substantial interspecific variability in oxygen sensitivity, there was no evidence for size×DO interactions. These data do not support the oxygen hypothesis of Antarctic pycnogonid gigantism and suggest that explanations must be sought in other ecological or evolutionary processes. PMID:19129117

  10. Ciliated protozoa of two antarctic lakes: analysis by quantitative protargol staining and examination of artificial substrates

    Science.gov (United States)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Coats, D. W.; Wharton RA, J. r. (Principal Investigator)

    1999-01-01

    Planktonic and artificial substrate-associated ciliates have been identified in two perennially ice-covered antarctic lakes of the McMurdo Dry Valleys. Abundances estimated by quantitative protargol staining ranged from < 5 to 31690 cells l-1, levels that are comparable to those previously obtained using other methods. Nineteen ciliate taxa were identified from these lakes, with the most frequently encountered genera being Plagiocampa, Askenasia, Monodinium, Sphaerophrya and Vorticella. The taxonomic findings compare favorably with those of previous investigators; however four previously unreported genera were observed in both Lakes Fryxell and Hoare. The variability in the depth distributions of ciliates in Lake Fryxell is explained in terms of lake physicochemical properties and ciliate prey distributions, while factors related to temporal succession in the Lake Hoare assemblage remain unexplained. Local marine or temperate zone freshwater habitats are a more likely source than the surrounding dry valleys soils for present ciliate colonists in these lakes. Although the taxonomic uncertainties require further examination, our results suggest that ciliate populations in these antarctic lakes undergo significant fluctuations and are more diverse than was previously recognized.

  11. Seasonal trophic ecology of the dominant Antarctic coral Malacobelemnon daytoni (Octocorallia, Pennatulacea, Kophobelemnidae).

    Science.gov (United States)

    Servetto, N; Rossi, S; Fuentes, V; Alurralde, G; Lagger, C; Sahade, R

    2017-09-01

    Antarctic ecosystems present highly marked seasonal patterns in energy input, which in turn determines the biology and ecology of marine invertebrate species. This relationship is stronger at lower levels of the food web, while upper levels may be less dependent on primary production pulses. The pennatulid Malacobelemnon daytoni, is one of the most abundant species in Potter Cove, Antarctica. In order to assess its trophic ecology and energetic strategies, its biochemical (carbohydrates, proteins and lipids), Fatty Acid (FA) and Stable Isotope (SI) (δ 15 N and δ 13 C) compositions were studied over a year-round period. The FA and SI profiles suggest an omnivorous diet and opportunistic feeding strategy for the species. These results, together with biochemical analysis (higher lipid and carbohydrate concentration observed in July and October 2009), support the hypothesis that resuspension events may be an important source of energy, reducing the seasonality of food depletion periods in winter. The evidence presented here gives us a better insight into the success that this species has in Potter Cove and under the current environmental changes experienced by the Antarctic Peninsula. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Macronutrient and carbon supply, uptake and cycling across the Antarctic Peninsula shelf during summer.

    Science.gov (United States)

    Henley, Sian F; Jones, Elizabeth M; Venables, Hugh J; Meredith, Michael P; Firing, Yvonne L; Dittrich, Ribanna; Heiser, Sabrina; Stefels, Jacqueline; Dougans, Julie

    2018-06-28

    The West Antarctic Peninsula shelf is a region of high seasonal primary production which supports a large and productive food web, where macronutrients and inorganic carbon are sourced primarily from intrusions of warm saline Circumpolar Deep Water. We examined the cross-shelf modification of this water mass during mid-summer 2015 to understand the supply of nutrients and carbon to the productive surface ocean, and their subsequent uptake and cycling. We show that nitrate, phosphate, silicic acid and inorganic carbon are progressively enriched in subsurface waters across the shelf, contrary to cross-shelf reductions in heat, salinity and density. We use nutrient stoichiometric and isotopic approaches to invoke remineralization of organic matter, including nitrification below the euphotic surface layer, and dissolution of biogenic silica in deeper waters and potentially shelf sediment porewaters, as the primary drivers of cross-shelf enrichments. Regenerated nitrate and phosphate account for a significant proportion of the total pools of these nutrients in the upper ocean, with implications for the seasonal carbon sink. Understanding nutrient and carbon dynamics in this region now will inform predictions of future biogeochemical changes in the context of substantial variability and ongoing changes in the physical environment.This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'. © 2018 The Authors.

  13. Secondary organic aerosols over oceans via oxidation of isoprene and monoterpenes from Arctic to Antarctic.

    Science.gov (United States)

    Hu, Qi-Hou; Xie, Zhou-Qing; Wang, Xin-Ming; Kang, Hui; He, Quan-Fu; Zhang, Pengfei

    2013-01-01

    Isoprene and monoterpenes are important precursors of secondary organic aerosols (SOA) in continents. However, their contributions to aerosols over oceans are still inconclusive. Here we analyzed SOA tracers from isoprene and monoterpenes in aerosol samples collected over oceans during the Chinese Arctic and Antarctic Research Expeditions. Combined with literature reports elsewhere, we found that the dominant tracers are the oxidation products of isoprene. The concentrations of tracers varied considerably. The mean average values were approximately one order of magnitude higher in the Northern Hemisphere than in the Southern Hemisphere. High values were generally observed in coastal regions. This phenomenon was ascribed to the outflow influence from continental sources. High levels of isoprene could emit from oceans and consequently have a significant impact on marine SOA as inferred from isoprene SOA during phytoplankton blooms, which may abruptly increase up to 95 ng/m³ in the boundary layer over remote oceans.

  14. Shifting baselines in Antarctic ecosystems; ecophysiological response to warming in Lissarca miliaris at Signy Island, Antarctica.

    Science.gov (United States)

    Reed, Adam J; Thatje, Sven; Linse, Katrin

    2012-01-01

    The Antarctic Peninsula has experienced a rapid increase in atmospheric temperature over the last 50 years. Whether or not marine organisms thriving in this cold stenothermal environment are able to cope with warming is of concern. Here, we present changes to the growth and shell characteristics of the ecologically important, small and short lived brooding bivalve Lissarca miliaris from Signy Island, Antarctica. Using material collected from the 1970's to the present day, we show an increase in growth rate and adult shell deterioration accompanied by a decrease in offspring size, associated with an increase in annual average temperatures. Critical changes to the bivalve's ecology seen today evidence the problem of a shift in baseline since the onset of warming recorded in Antarctica. These small bivalves are demonstrating ecophysiological responses to subtle warming that, provided warming continues, could soon surpass a physiological tipping point, adding to warming associated threats such as increased predatory pressure and ocean acidification.

  15. Shifting baselines in Antarctic ecosystems; ecophysiological response to warming in Lissarca miliaris at Signy Island, Antarctica.

    Directory of Open Access Journals (Sweden)

    Adam J Reed

    Full Text Available The Antarctic Peninsula has experienced a rapid increase in atmospheric temperature over the last 50 years. Whether or not marine organisms thriving in this cold stenothermal environment are able to cope with warming is of concern. Here, we present changes to the growth and shell characteristics of the ecologically important, small and short lived brooding bivalve Lissarca miliaris from Signy Island, Antarctica. Using material collected from the 1970's to the present day, we show an increase in growth rate and adult shell deterioration accompanied by a decrease in offspring size, associated with an increase in annual average temperatures. Critical changes to the bivalve's ecology seen today evidence the problem of a shift in baseline since the onset of warming recorded in Antarctica. These small bivalves are demonstrating ecophysiological responses to subtle warming that, provided warming continues, could soon surpass a physiological tipping point, adding to warming associated threats such as increased predatory pressure and ocean acidification.

  16. New Carcharhiniform Sharks (Chondrichthyes, Elasmobranchii) from the Early to Middle Eocene of Seymour Island, Antarctic Peninsula

    Science.gov (United States)

    Engelbrecht, Andrea; Mörs, Thomas; Reguero, Marcelo A.; Kriwet, Jürgen

    2018-01-01

    Seymour Island, Antarctic Peninsula, is known for its wealth of fossil remains. This island provides one of the richest fossiliferous Paleogene sequences in the world. Chondrichthyans seemingly dominate this Eocene marine fauna and offer a rare insight into high-latitude faunas during the Palaeogene. So far, only a few isolated teeth of carcharhinid sharks have been reported from Seymour Island. Bulk sampling in the well-exposed La Meseta and Submeseta formations yielded new and abundant chondrichthyan material, including numerous teeth of carcharhinid and triakid sharks. Here, we present a reevaluation of the previously described carcharhinid remains and a description of new taxa: Meridiogaleus cristatus, gen. et sp. nov., Kallodentis rythistemma, gen. et sp. nov., Abdounia richteri, sp. nov., and Abdounia mesetae, sp. nov. The carcharhiniforms Mustelus sp. and Galeorhinus sp. are reported based on rare material, whereas teeth previously assigned to Scoliodon represent a nomen dubium. PMID:29551850

  17. Antarctic Ice Sheet Discharge Driven by Atmosphere-Ocean Feedbacks Across the Last Glacial Termination

    Science.gov (United States)

    Fogwill, C. J.; Turney, C. S.; Golledge, N. R.; Etheridge, D. M.; Rubino, M.; Thornton, D.; Baker, A.; Weber, M. E.; Woodward, J.; van Ommen, T. D.; Moy, A. D.; Davies, S. M.; Bird, M. I.; Winter, K.; Munksgaard, N.; Menviel, L.; Rootes, C.; Vohra, J.; Rivera, A.; Cooper, A.

    2016-12-01

    Reconstructing the dynamic response of the Antarctic ice sheets to warming during the Last Glacial Termination (LGT; 18,000-11,650 yrs ago) allows us to identify ice-climate feedbacks that could improve future projections1,2. Whilst the sequence of events during this period are reasonably well-known, relatively poor chronological control has precluded precise alignment of ice, atmospheric and marine records2, making it difficult to assess relationships between Antarctic ice-sheet dynamics, climate change and sea-level rise3-5. Here we present results from a highly-resolved `horizontal ice core'6,7 from the Weddell Sea Embayment, which records millennial-scale ice-sheet dynamics across this extensive sector of Antarctica. Counterintuitively, we find ice-sheet surface drawdown of 600 m across the Antarctic Cold Reversal (ACR; 14,600-12,700 yrs ago)5, with stabilisation during the subsequent millennia of atmospheric warming. Earth system and ice-sheet modelling highlights that this response was likely sustained by strong ocean-ice feedbacks4,8; however, the drivers remain uncertain. Given the coincidence of the ice-sheet changes recorded with marked shifts in atmospheric circulation9,10,11we suggest that millennial-scale Antarctic ice-sheet behaviour was initiated and sustained by global atmospheric teleconnections across the LGT. This has important ramifications ice-sheet stability under contemporary climate change, with changing atmospheric and oceanic circulation patterns. 1 Collins, M. et al. in Climate Change 2013: The Physical Science Basis. 2 Weber, M. E. et al. Nature 510, 134-138, (2014). 3 Weaver, A. J., et al., Science 299, 1709-1713, (2003). 4 Golledge, N. R. et al. Nat Commun 5, (2014). 5 Pedro, J. B. et al. Nature Geosci9. 51-55 (2015). 6 Turney, C. S. M. et al. Journal of Quaternary Science 28, 697-704 (2013). 7 Winter, K. et al. Geophys. Res. Lett.43. 5. 2019-2026 (2016). 8 Menviel, L., A. et al., Quaternary Science Reviews 30, 1155-1172 (2011). 9 Hogg

  18. Differing foraging strategies influence mercury (Hg) exposure in an Antarctic penguin community.

    Science.gov (United States)

    Polito, Michael J; Brasso, Rebecka L; Trivelpiece, Wayne Z; Karnovsky, Nina; Patterson, William P; Emslie, Steven D

    2016-11-01

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Sea-level response to abrupt ocean warming of Antarctic ice shelves

    Science.gov (United States)

    Pattyn, Frank

    2016-04-01

    Antarctica's contribution to global sea-level rise increases steadily. A fundamental question remains whether the ice discharge will lead to marine ice sheet instability (MISI) and collapse of certain sectors of the ice sheet or whether ice loss will increase linearly with the warming trends. Therefore, we employ a newly developed ice sheet model of the Antarctic ice sheet, called f.ETISh (fast Elementary Thermomechanical Ice Sheet model) to simulate ice sheet response to abrupt perturbations in ocean and atmospheric temperature. The f.ETISh model is a vertically integrated hybrid (SSA/SIA) ice sheet model including ice shelves. Although vertically integrated, thermomechanical coupling is ensured through a simplified representation of ice sheet thermodynamics based on an analytical solution of the vertical temperature profile, including strain heating and horizontal advection. The marine boundary is represented by a flux condition either coherent with power-law basal sliding (Pollard & Deconto (2012) based on Schoof (2007)) or according to Coulomb basal friction (Tsai et al., 2015), both taking into account ice-shelf buttressing. Model initialization is based on optimization of the basal friction field. Besides the traditional MISMIP tests, new tests with respect to MISI in plan-view models have been devised. The model is forced with stepwise ocean and atmosphere temperature perturbations. The former is based on a parametrised sub-shelf melt (limited to ice shelves), while the latter is based on present-day mass balance/surface temperature and corrected for elevation changes. Surface melting is introduced using a PDD model. Results show a general linear response in mass loss to ocean warming. Nonlinear response due to MISI occurs under specific conditions and is highly sensitive to the basal conditions near the grounding line, governed by both the initial conditions and the basal sliding/deformation model. The Coulomb friction model leads to significantly higher

  20. Activities of the summer party of the 37th Japanese Antarctic Research Expedition 1995-1996

    Directory of Open Access Journals (Sweden)

    Hiroshi Kanda

    1999-07-01

    Full Text Available The summer activities in the 1995/1996 austral summer of the 37th Japanese Antarctic Research Expedition (JARE-37 are reported. The JARE-37 consisted of 16 members of the summer party, one news reporter and one graduate student. The Antarctic research vessel, SHIRASE, left Tokyo on 14th November 1995 and arrived at Fremantle, West Australia on 28th November. She reached the pack ice edge near Lutzow-Holm Bay on 14th December and anchored at Syowa Station on 24th December. Transportation of cargo by helicopter to Syowa Station and to the transport point (S16 for Dome Fuji Station was carried out between 16th December 1995 and 9th January 1996. A total of 1069.5 tons of cargo, including light oil transported by pipe and freight by oversnow vehicles, were transported. Construction to replace old buildings and facilities at Syowa Station were carried out. Main construction, a building for storage, continued throughout the summer at Syowa Station. In addition, an emergency power house and a seismographic hut were built, and the old power house was torn down. Summer research programs included a marine physical survey, atmospheric work, and field surveys in ice-free areas along the Soya Coast. All of the summer party left Syowa Station on 12th February and headed to Sydney, East Australia. En route, a geodesic survey, geological and biological research were carried out at ice-free areas along the Prince Olav Coast and oceanographic, marine biological observations, geomagnetism and other work were carried out on board. Members of the summer party of JARE-37 returned to Narita by air on 27th March 1996.

  1. Otters, Marine

    Science.gov (United States)

    Estes, James A.; Bodkin, James L.; Ben-David, M.; Perrin, William F.; Würsing, Bernd; Thewissen, J.G.M.

    2009-01-01

    The otters (Mustelidae; Lutrinae) provide an exceptional perspective into the evolution of marine living by mammals. Most extant marine mammals (e.g. the cetaceans, pinnipeds, and sirenians) have been so highly modified by long periods of selection for life in the sea that they bear little resemblance to their terrestrial ancestors. Marine otters, in contrast, are more recent expatriates from freshwater habitats and some species still live in both environments. Contrasts among species within the otters, and among the otters, terrestrial mammals, and the more highly adapted pinnipeds and cetaceans provide powerful insights into mammalian adaptations to life in the sea (Estes, 1989). Among the marine mammals, sea otters (Enhydra lutris, Fig. 1) provide the clearest understanding of consumer-induced effects on ecosystem function. This is due in part to opportunities provided by history and in part to the relative ease with which shallow coastal systems where sea otters live can be observed and studied. Although more difficult to study than sea otters, other otter species reveal the connectivity among the marine, freshwater, and terrestrial systems. These three qualities of the otters – their comparative biology, their role as predators, and their role as agents of ecosystem connectivity – are what make them interesting to marine mammalogy.The following account provides a broad overview of the comparative biology and ecology of the otters, with particular emphasis on those species or populations that live in the sea. Sea otters are features prominently, in part because they live exclusively in the sea whereas other otters have obligate associations with freshwater and terrestrial environments (Kenyon, 1969; Riedman and Estes, 1990).

  2. Marine Battlefields

    DEFF Research Database (Denmark)

    Harðardóttir, Sara

    as they are an important food source for various marine animals. For both phytoand zooplankton predation is a major cause of mortality, and strategies for protection or avoidance are important for survival. Diatoms of the genera Nitzschia and Pseudo-nitzschia are known to produce a neuro-toxin, domoic acid (DA). Despite......Phytoplankton species are photosynthetic organisms found in most aquatic habitats. In the ocean, phytoplankton are tremendously important because they produce the energy that forms the base of the marine food web. Zooplankton feed on phytoplankton and mediate the energy to higher trophic levels...

  3. Seabed images from Southern Ocean shelf regions off the northern Antarctic Peninsula and in the southeastern Weddell Sea

    Science.gov (United States)

    Piepenburg, Dieter; Buschmann, Alexander; Driemel, Amelie; Grobe, Hannes; Gutt, Julian; Schumacher, Stefanie; Segelken-Voigt, Alexandra; Sieger, Rainer

    2017-07-01

    Recent advances in underwater imaging technology allow for the gathering of invaluable scientific information on seafloor ecosystems, such as direct in situ views of seabed habitats and quantitative data on the composition, diversity, abundance, and distribution of epibenthic fauna. The imaging approach has been extensively used within the research project DynAMo (Dynamics of Antarctic Marine Shelf Ecosystems) at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research Bremerhaven (AWI), which aimed to comparatively assess the pace and quality of the dynamics of Southern Ocean benthos. Within this framework, epibenthic spatial distribution patterns have been comparatively investigated in two regions in the Atlantic sector of the Southern Ocean: the shelf areas off the northern tip of the Antarctic Peninsula, representing a region with above-average warming of surface waters and sea-ice reduction, and the shelves of the eastern Weddell Sea as an example of a stable high-Antarctic marine environment that is not (yet) affected by climate change. The AWI Ocean Floor Observation System (OFOS) was used to collect seabed imagery during two cruises of the German research vessel Polarstern, ANT-XXIX/3 (PS81) to the Antarctic Peninsula from January to March 2013 and ANT-XXXI/2 (PS96) to the Weddell Sea from December 2015 to February 2016. Here, we report on the image and data collections gathered during these cruises. During PS81, OFOS was successfully deployed at a total of 31 stations at water depths between 29 and 784 m. At most stations, series of 500 to 530 pictures ( > 15 000 in total, each depicting a seabed area of approximately 3.45 m2 or 2.3 × 1.5 m) were taken along transects approximately 3.7 km in length. During PS96, OFOS was used at a total of 13 stations at water depths between 200 and 754 m, yielding series of 110 to 293 photos (2670 in total) along transects 0.9 to 2.6 km in length. All seabed images taken during the two cruises

  4. Radarsat Antarctic Mapping Project Digital Elevation Model, Version 2

    Data.gov (United States)

    National Aeronautics and Space Administration — The high-resolution Radarsat Antarctic Mapping Project (RAMP) Digital Elevation Model (DEM) combines topographic data from a variety of sources to provide consistent...

  5. Searching for eukaryotic life preserved in Antarctic permafrost

    DEFF Research Database (Denmark)

    Zucconi, L.; Selbmann, L.; Buzzini, P.

    2012-01-01

    Fungi and yeasts isolated in pure culture from Antarctic permafrost collected at different depths in the McMurdo Dry Valleys were identified with cultural, physiological and molecular methods. Fungi belonged to the genera Penicillium, Eurotium, Cladosporium, Alternaria, Engyodonthium, Aureobasidium...

  6. STRATEGIES AND KINETICS OF PHOTOACCLIMATION IN 3 ANTARCTIC NANOPHYTOFLAGELLATES

    NARCIS (Netherlands)

    BUMA, AGJ; NOORDELOOS, AAM; LARSEN, J

    Three Antarctic nanophytoflagellates (two cryptophyte species and a Pyramimonas sp.) were compared for their capacity to photoacclimate and for their kinetic responses in changing photic environments. Division rate, cell size, cellular fluorescence, and chlorophyll a content were measured during

  7. Climate Prediction Center (CPC) Daily Antarctic Oscillation Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Antarctic Oscillation (AAO) is a leading teleconnection pattern in the Southern Hemisphere circulation. It is calculated as the first Empirical Orthogonal...

  8. Biological invasions in the Antarctic: extent, impacts and implications.

    Science.gov (United States)

    Frenot, Yves; Chown, Steven L; Whinam, Jennie; Selkirk, Patricia M; Convey, Peter; Skotnicki, Mary; Bergstrom, Dana M

    2005-02-01

    Alien microbes, fungi, plants and animals occur on most of the sub-Antarctic islands and some parts of the Antarctic continent. These have arrived over approximately the last two centuries, coincident with human activity in the region. Introduction routes have varied, but are largely associated with movement of people and cargo in connection with industrial, national scientific program and tourist operations. The large majority of aliens are European in origin. They have both direct and indirect impacts on the functioning of species-poor Antarctic ecosystems, in particular including substantial loss of local biodiversity and changes to ecosystem processes. With rapid climate change occurring in some parts of Antarctica, elevated numbers of introductions and enhanced success of colonization by aliens are likely, with consequent increases in impacts on ecosystems. Mitigation measures that will substantially reduce the risk of introductions to Antarctica and the sub-Antarctic must focus on reducing propagule loads on humans, and their food, cargo, and transport vessels.

  9. Climate Prediction Center(CPC)Monthly Antarctic Oscillation Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Antarctic Oscillation (AAO) is a leading teleconnection pattern in the Southern Hemisphere circulation. It is calculated as the first Empirical Orthogonal...

  10. Antarctic Active Subglacial Lake Inventory from ICESat Altimetry, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains lake boundaries, volume changes, and gridded elevations for 124 active subglacial lakes beneath the Antarctic ice sheet. Lakes were identified...

  11. Photosynthesis in a sub-Antarctic shore-zone lichen

    NARCIS (Netherlands)

    Smith, V.; Gremmen, N.J.M.

    2001-01-01

    Photosynthetic responses to moisture, light, temperature, salinity and inorganic nitrogen fertilization are reported for a shore-zone lichen Turgidiusculum complicatulum (formerly Mastodia tesselata), a possible recent introduction to sub-Antarctic Marion Island. Optimum moisture contents for net

  12. German Antarctic Receiving Station (GARS) O'Higgins

    Science.gov (United States)

    Neidhardt, Alexander; Ploetz, Christian; Kluegel, Thomas

    2013-01-01

    In 2012, the German Antarctic Receiving Station (GARS) O'Higgins contributed to the IVS observing program with four observation sessions. Maintenance and upgrades were made, and a new replacement dewar is under construction in the observatory at Yebes, Spain.

  13. Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years

    Directory of Open Access Journals (Sweden)

    A. S. Gardner

    2018-02-01

    Full Text Available Ice discharge from large ice sheets plays a direct role in determining rates of sea-level rise. We map present-day Antarctic-wide surface velocities using Landsat 7 and 8 imagery spanning 2013–2015 and compare to earlier estimates derived from synthetic aperture radar, revealing heterogeneous changes in ice flow since ∼ 2008. The new mapping provides complete coastal and inland coverage of ice velocity north of 82.4° S with a mean error of < 10 m yr−1, resulting from multiple overlapping image pairs acquired during the daylight period. Using an optimized flux gate, ice discharge from Antarctica is 1929 ± 40 Gigatons per year (Gt yr−1 in 2015, an increase of 36 ± 15 Gt yr−1 from the time of the radar mapping. Flow accelerations across the grounding lines of West Antarctica's Amundsen Sea Embayment, Getz Ice Shelf and Marguerite Bay on the western Antarctic Peninsula, account for 88 % of this increase. In contrast, glaciers draining the East Antarctic Ice Sheet have been remarkably constant over the period of observation. Including modeled rates of snow accumulation and basal melt, the Antarctic ice sheet lost ice at an average rate of 183 ± 94 Gt yr−1 between 2008 and 2015. The modest increase in ice discharge over the past 7 years is contrasted by high rates of ice sheet mass loss and distinct spatial patters of elevation lowering. The West Antarctic Ice Sheet is experiencing high rates of mass loss and displays distinct patterns of elevation lowering that point to a dynamic imbalance. We find modest increase in ice discharge over the past 7 years, which suggests that the recent pattern of mass loss in Antarctica is part of a longer-term phase of enhanced glacier flow initiated in the decades leading up to the first continent-wide radar mapping of ice flow.

  14. Morphogenesis of Antarctic Paleosols: Martian Analogue

    Science.gov (United States)

    Mahaney, W. C.; Dohm, J. M.; Baker, V. R.; Newsom, Horton E.; Malloch, D.; Hancock, R. G. V.; Campbell, Iain; Sheppard, D.; Milner, M. W.

    2001-11-01

    Samples of horizons in paleosols from the Quartermain Mountains of the Antarctic Dry Valleys (Aztec and New Mountain areas) were analyzed for their physical characteristics, mineralogy, chemical composition, and microbiology to determine the accumulation and movement of salts and other soluble constituents and the presence/absence of microbial populations. Salt concentrations are of special interest because they are considered to be a function of age, derived over time, in part from nearby oceanic and high-altitude atmospheric sources. The chemical composition of ancient Miocene-age paleosols in these areas is the direct result of the deposition and weathering of airborne-influxed salts and other materials, as well as the weathering of till derived principally from local dolerite and sandstone outcrops. Paleosols nearer the coast have greater contents of Cl, whereas near the inland ice sheet, nitrogen tends to increase on a relative basis. The accumulation and vertical distribution of salts and other soluble chemical elements indicate relative amounts of movement in the profile over long periods of time, in the order of several million years. Four of the six selected subsamples from paleosol horizons in two ancient soil profiles contained nil concentrations of bacteria and fungi. However, two horizons at depths of between 3 and 8 cm, in two profiles, yielded several colonies of the fungi Beauveria bassiana and Penicillium brevicompactum, indicating very minor input of organic carbon. Beauveria bassiana is often reported in association with insects and is used commercially for the biological control of some insect pests. Penicillium species are commonly isolated from Arctic, temperate, and tropical soils and are known to utilize a wide variety of organic carbon and nitrogen compounds. The cold, dry soils of the Antarctic bear a close resemblance to various present and past martian environments where similar weathering could occur and possible microbial populations

  15. Functional ecology of an Antarctic Dry Valley

    Science.gov (United States)

    Chan, Yuki; Van Nostrand, Joy D.; Zhou, Jizhong; Pointing, Stephen B.

    2013-01-01

    The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are critically at risk from climate change. The terrestrial landscape is dominated by oligotrophic mineral soils and extensive exposed rocky surfaces where biota are largely restricted to microbial communities, although their ability to perform the majority of geobiological processes has remained largely uncharacterized. Here, we identified functional traits that drive microbial survival and community assembly, using a metagenomic approach with GeoChip-based functional gene arrays to establish metabolic capabilities in communities inhabiting soil and rock surface niches in McKelvey Valley. Major pathways in primary metabolism were identified, indicating significant plasticity in autotrophic, heterotrophic, and diazotrophic strategies supporting microbial communities. This represents a major advance beyond biodiversity surveys in that we have now identified how putative functional ecology drives microbial community assembly. Significant differences were apparent between open soil, hypolithic, chasmoendolithic, and cryptoendolithic communities. A suite of previously unappreciated Antarctic microbial stress response pathways, thermal, osmotic, and nutrient limitation responses were identified and related to environmental stressors, offering tangible clues to the mechanisms behind the enduring success of microorganisms in this seemingly inhospitable terrain. Rocky substrates exposed to larger fluctuations in environmental stress supported greater functional diversity in stress-response pathways than soils. Soils comprised a unique reservoir of genes involved in transformation of organic hydrocarbons and lignin-like degradative pathways. This has major implications for the evolutionary origin of the organisms, turnover of recalcitrant substrates in Antarctic soils, and predicting future responses to anthropogenic pollution. PMID:23671121

  16. Antarctic Martian Meteorites at Johnson Space Center

    Science.gov (United States)

    Funk, R. C.; Satterwhite, C. E.; Righter, K.; Harrington, R.

    2018-01-01

    This past year marked the 40th anniversary of the first Martian meteorite found in Antarctica by the ANSMET Antarctic Search for Meteorites) program, ALH 77005. Since then, an additional 14 Martian meteorites have been found by the ANSMET program making for a total of 15 Martian meteorites in the U. S. Antarctic meteorite collection at Johnson Space Center (JSC). Of the 15 meteorites, some have been paired so the 15 meteorites actually represent a total of approximately 9 separate samples. The first Martian meteorite found by ANSMET was ALH 77005 (482.500 g), a lherzolitic shergottite. When collected, this meteorite was split as a part of the joint expedition with the National Institute of Polar Research (NIPR) Japan. Originally classified as an "achondrite-unique", it was re-classified as a Martian lherzolitic shergottite in 1982. This meteorite has been allocated to 137 scientists for research and there are 180.934 g remaining at JSC. Two years later, one of the most significant Martian meteorites of the collection at JSC was found at Elephant Moraine, EET 79001 (7942.000 g), a shergottite. This meteorite is the largest in the Martian collection at JSC and was the largest stony meteorite sample collected during the 1979 season. In addition to its size, this meteorite is of particular interest because it contains a linear contact separating two different igneous lithologies, basaltic and olivine-phyric. EET 79001 has glass inclusions that contain noble gas and nitrogen compositions that are proportionally identical to the Martian atmosphere, as measured by the Viking spacecraft. This discovery helped scientists to identify where the "SNC" meteorite suite had originated, and that we actually possessed Martian samples. This meteorite has been allocated to 205 scientists for research and 5,298.435 g of sample is available.

  17. Glacial morphology and depositional sequences of the Antarctic Continental Shelf

    Science.gov (United States)

    ten Brink, Uri S.; Schneider, Christopher

    1995-01-01

    Proposes a simple model for the unusual depositional sequences and morphology of the Antarctic continental shelf. It considers the regional stratal geometry and the reversed morphology to be principally the results of time-integrated effects of glacial erosion and sedimentation related to the location of the ice grounding line. The model offers several guidelines for stratigraphic interpretation of the Antarctic shelf and a Northern Hemisphere shelf, both of which were subject to many glacial advances and retreats. -Authors

  18. Leadership in politics and science within the Antarctic Treaty

    OpenAIRE

    John R. Dudeney; David W.H. Walton

    2012-01-01

    For over 50 years the Antarctic has been governed through the Antarctic Treaty, an international agreement now between 49 nations of whom 28 Consultative Parties (CPs) undertake the management role. Ostensibly, these Parties have qualified for their position on scientific grounds, though diplomacy also plays a major role. This paper uses counts of policy papers and science publications to assess the political and scientific outputs of all CPs over the last 18 years. We show that a subset of t...

  19. Wind profile radar for study of Antarctic air circulation

    International Nuclear Information System (INIS)

    Ragaini, E.; Sarango, M.F.; Vasquez, E.H.

    1992-01-01

    After a brief discussion of meteorological methods used in the Antarctic, the paper gives an outline of a coordinated international research project whose objective is to set up a wind profiler radar station that would give meteorologists information regarding Antarctic atmospheric dynamics useful in their investigation of the causes and effects of the hole in the ozone layer. The radar instrumentation is to provide continuous readings of wind velocity at varying altitudes above the polar continent

  20. Distribution of sewage pollution around a maritime Antarctic research station indicated by faecal coliforms, Clostridium perfringens and faecal sterol markers

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Kevin A.; Thompson, Anu

    2004-02-01

    This study describes the distribution of sewage pollution markers (faecal coliforms, Clostridium perfringens and faecal sterols) in seawater and marine sediments around Rothera Research Station, Antarctic Peninsula. Untreated sewage waste has been released from this site since 1975, creating the potential for long-term contamination of the benthic environment. Faecal coliform concentrations in seawater reached background levels within 300 m of the outfall. In sediment cores, both C. perfringens and faecal coliform concentrations declined with distance from the outfall, though C. perfringens persisted at greater depths in the sediment. High concentrations of 5{beta}(H)-cholestan-3{beta}-ol (coprostanol) relative to the corresponding 5{alpha}-epimer (cholestanol), indicative of sewage pollution, were only found in sediments within 200 m of the sewage outfall. This study has shown that sewage contamination is limited to the immediate vicinity of the sewage outfall. Nevertheless, a sewage treatment plant was installed in February 2003 to reduce this contamination further. - Sewage contamination of seawater and marine sediments near Rothera Research Station (Antarctic Peninsula) was limited to the immediate vicinity of the outfall.

  1. Distribution of sewage pollution around a maritime Antarctic research station indicated by faecal coliforms, Clostridium perfringens and faecal sterol markers

    International Nuclear Information System (INIS)

    Hughes, Kevin A.; Thompson, Anu

    2004-01-01

    This study describes the distribution of sewage pollution markers (faecal coliforms, Clostridium perfringens and faecal sterols) in seawater and marine sediments around Rothera Research Station, Antarctic Peninsula. Untreated sewage waste has been released from this site since 1975, creating the potential for long-term contamination of the benthic environment. Faecal coliform concentrations in seawater reached background levels within 300 m of the outfall. In sediment cores, both C. perfringens and faecal coliform concentrations declined with distance from the outfall, though C. perfringens persisted at greater depths in the sediment. High concentrations of 5β(H)-cholestan-3β-ol (coprostanol) relative to the corresponding 5α-epimer (cholestanol), indicative of sewage pollution, were only found in sediments within 200 m of the sewage outfall. This study has shown that sewage contamination is limited to the immediate vicinity of the sewage outfall. Nevertheless, a sewage treatment plant was installed in February 2003 to reduce this contamination further. - Sewage contamination of seawater and marine sediments near Rothera Research Station (Antarctic Peninsula) was limited to the immediate vicinity of the outfall

  2. Marine Science

    African Journals Online (AJOL)

    Science. The journal has a new and more modern layout, published online only, and the editorial. Board was increased to include more disciplines pertaining to marine sciences. While important chal- lenges still lie ahead, we are steadily advancing our standard to increase visibility and dissemination throughout the global ...

  3. Marine Mammals.

    Science.gov (United States)

    Meith, Nikki

    Marine mammals have not only fascinated and inspired human beings for thousands of years, but they also support a big business by providing flesh for sea-borne factories, sustaining Arctic lifestyles and traditions, and attracting tourists to ocean aquaria. While they are being harpooned, bludgeoned, shot, netted, and trained to jump through…

  4. Marine Science

    African Journals Online (AJOL)

    Mauritius Marine Conservation Society through their. Abstract. While no populations of seals are resident in the tropical Indian Ocean, vagrant animals are occasionally sighted in the region. Here we detail two new sightings of pinnipeds in the Mascarene Islands (Mauritius, Reunion and Rodri- gues) since 1996 and review ...

  5. Marine Science

    African Journals Online (AJOL)

    J O U R N A L O F. Marine Science. Coral reefs of Mauritius in a changing global climate ..... in confined aquifers, and a lesser influence in uncon- fined systems. On the ... massive cloud cover during the critical months, some. 70% bleaching ...

  6. Marine Science

    African Journals Online (AJOL)

    Copy Editor Timothy Andrew. Published ... 2007; Zhou et al., 2009) and they play an important role in the ... At both sites, zonal variation in TMPB was evident with significantly higher C-biomass closer to ... ton is considered to be an essential parameter in eco- systems ...... logical significance of toxic marine dinoflagellates.

  7. Marine Science

    African Journals Online (AJOL)

    sustainable coastal development in the region, as well as contributing to the ... between humans and the coastal and marine environment. ... exploitation for timber, fuel wood, aquaculture, urban. Abstract. Given the high dependence of coastal communities on natural resources, mangrove conservation is a challenge in.

  8. Marine Science

    African Journals Online (AJOL)

    No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means ... USA/Norway ... The last couple of years have been a time of change for the Western Indian Ocean Journal of Marine.

  9. Marine Science

    African Journals Online (AJOL)

    Chief Editor José Paula | Faculty of Sciences of University of Lisbon, Portugal. Copy Editor Timothy Andrew. Published biannually. Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high quality research generated in the Western Indian Ocean (WIO) ...

  10. The genome of the Antarctic-endemic copepod, Tigriopus kingsejongensis.

    Science.gov (United States)

    Kang, Seunghyun; Ahn, Do-Hwan; Lee, Jun Hyuck; Lee, Sung Gu; Shin, Seung Chul; Lee, Jungeun; Min, Gi-Sik; Lee, Hyoungseok; Kim, Hyun-Woo; Kim, Sanghee; Park, Hyun

    2017-01-01

    The Antarctic intertidal zone is continuously subjected to extremely fluctuating biotic and abiotic stressors. The West Antarctic Peninsula is the most rapidly warming region on Earth. Organisms living in Antarctic intertidal pools are therefore interesting for research into evolutionary adaptation to extreme environments and the effects of climate change. We report the whole genome sequence of the Antarctic-endemic harpacticoid copepod Tigriopus kingsejongensi . The 37 Gb raw DNA sequence was generated using the Illumina Miseq platform. Libraries were prepared with 65-fold coverage and a total length of 295 Mb. The final assembly consists of 48 368 contigs with an N50 contig length of 17.5 kb, and 27 823 scaffolds with an N50 contig length of 159.2 kb. A total of 12 772 coding genes were inferred using the MAKER annotation pipeline. Comparative genome analysis revealed that T. kingsejongensis -specific genes are enriched in transport and metabolism processes. Furthermore, rapidly evolving genes related to energy metabolism showed positive selection signatures. The T. kingsejongensis genome provides an interesting example of an evolutionary strategy for Antarctic cold adaptation, and offers new genetic insights into Antarctic intertidal biota. © The Author 2017. Published by Oxford University Press.

  11. Parasites of the Antarctic toothfish (Dissostichus mawsoni Norman, 1937 (Perciformes, Nototheniidae in the Pacific sector of the Antarctic

    Directory of Open Access Journals (Sweden)

    Ilya I. Gordeev

    2016-06-01

    Full Text Available The Antarctic toothfish (Dissostichus mawsoni Norman, 1937 is one of the main target species of commercial fisheries in the Antarctic. It is an endemic and is found along the shelf of Antarctica, as well as on the slopes of seamounts, underwater elevations and islands in the sub-Antarctic. It feeds on a variety of fish and cephalopods and can be an intermediate/paratenic host of some helminthes, whose final hosts are whales, seals, large rays and sharks. This article presents new data on toothfish infection in the Pacific sector of the Antarctic. Specimens were examined during commercial longline fishing in the Ross Sea and the Amundsen Sea in January–February 2013. Fourteen species of parasites were found using standard parasitological methods and genetic analysis.

  12. A long term strategy for Antarctic tourism : The key to decision making within the Antarctic Treaty System?

    NARCIS (Netherlands)

    Bastmeijer, C.J.; Maher, P.; Stewart, E.; Lück, M.

    2011-01-01

    The fast increase of Antarctic tourism raises various management questions. Questions relating to the safety of tourists, questions regarding the interaction between science and tourism and questions relating to direct, indirect or cumulative affects on Antarctica's environment and wilderness

  13. Climate change and Southern Ocean ecosystems I: how changes in physical habitats directly affect marine biota.

    Science.gov (United States)

    Constable, Andrew J; Melbourne-Thomas, Jessica; Corney, Stuart P; Arrigo, Kevin R; Barbraud, Christophe; Barnes, David K A; Bindoff, Nathaniel L; Boyd, Philip W; Brandt, Angelika; Costa, Daniel P; Davidson, Andrew T; Ducklow, Hugh W; Emmerson, Louise; Fukuchi, Mitsuo; Gutt, Julian; Hindell, Mark A; Hofmann, Eileen E; Hosie, Graham W; Iida, Takahiro; Jacob, Sarah; Johnston, Nadine M; Kawaguchi, So; Kokubun, Nobuo; Koubbi, Philippe; Lea, Mary-Anne; Makhado, Azwianewi; Massom, Rob A; Meiners, Klaus; Meredith, Michael P; Murphy, Eugene J; Nicol, Stephen; Reid, Keith; Richerson, Kate; Riddle, Martin J; Rintoul, Stephen R; Smith, Walker O; Southwell, Colin; Stark, Jonathon S; Sumner, Michael; Swadling, Kerrie M; Takahashi, Kunio T; Trathan, Phil N; Welsford, Dirk C; Weimerskirch, Henri; Westwood, Karen J; Wienecke, Barbara C; Wolf-Gladrow, Dieter; Wright, Simon W; Xavier, Jose C; Ziegler, Philippe

    2014-10-01

    Antarctic and Southern Ocean (ASO) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This article reviews current and expected changes in ASO physical habitats in response to climate change. It then reviews how these changes may impact the autecology of marine biota of this polar region: microbes, zooplankton, salps, Antarctic krill, fish, cephalopods, marine mammals, seabirds, and benthos. The general prognosis for ASO marine habitats is for an overall warming and freshening, strengthening of westerly winds, with a potential pole-ward movement of those winds and the frontal systems, and an increase in ocean eddy activity. Many habitat parameters will have regionally specific changes, particularly relating to sea ice characteristics and seasonal dynamics. Lower trophic levels are expected to move south as the ocean conditions in which they are currently found move pole-ward. For Antarctic krill and finfish, the latitudinal breadth of their range will depend on their tolerance of warming oceans and changes to productivity. Ocean acidification is a concern not only for calcifying organisms but also for crustaceans such as Antarctic krill; it is also likely to be the most important change in benthic habitats over the coming century. For marine mammals and birds, the expected changes primarily relate to their flexibility in moving to alternative locations for food and the energetic cost of longer or more complex foraging trips for those that are bound to breeding colonies. Few species are sufficiently well studied to make comprehensive species-specific vulnerability assessments possible. Priorities for future work are discussed. © 2014 John Wiley & Sons Ltd.

  14. Isotopic niche variation in a higher trophic level ectotherm: highlighting the role of succulent plants in desert food webs.

    Directory of Open Access Journals (Sweden)

    Miguel Delibes

    Full Text Available Stable isotope analysis of animal tissues allows description of isotopic niches, whose axes in an n-dimensional space are the isotopic ratios, compared to a standard, of different isotope systems (e.g. δ(13C, δ(15N. Isotopic niches are informative about where an animal, population or species lives and about what it consumes. Here we describe inter- and intrapopulation isotopic niche (bidimensional δ(13C-δ(15N space of the Orange-throated whiptail (Aspidoscelis hyperythra, an arthropodivorous small lizard, in ten localities of Baja California Sur (Mexico. These localities range from extreme arid to subtropical conditions. Between 13 and 20 individuals were sampled at each locality and 1 cm of tail-tip was collected for isotope analysis. As expected, interpopulation niche width variation was much larger than intrapopulation one. Besides, isotopic variation was not related to age, sex or individual size of lizards. This suggests geographic variation of the isotopic niche was related to changes in the basal resources that fuel the trophic web at each locality. The position of Bayesian isotope ellipses in the δ-space indicated that whiptails in more arid localities were enriched in 13C, suggesting most of the carbon they ingested came from CAM succulent plants (cacti, agaves and in minor degree in C4 grasses. Contrarily, whiptails in subtropical areas were depleted in 13C, as they received more carbon from C3 scrubs and trees. Localities closer to sea-level tended to be enriched in 15N, but a clear influence of marine subsidies was detected only at individual level. The study contributes to identify the origin and pathways through which energy flows across the trophic webs of North American deserts.

  15. Isotopic Niche Variation in a Higher Trophic Level Ectotherm: Highlighting the Role of Succulent Plants in Desert Food Webs

    Science.gov (United States)

    Delibes, Miguel; Blazquez, Ma Carmen; Fedriani, Jose Maria; Granados, Arsenio; Soriano, Laura; Delgado, Antonio

    2015-01-01

    Stable isotope analysis of animal tissues allows description of isotopic niches, whose axes in an n-dimensional space are the isotopic ratios, compared to a standard, of different isotope systems (e.g. δ13C, δ15N). Isotopic niches are informative about where an animal, population or species lives and about what it consumes. Here we describe inter- and intrapopulation isotopic niche (bidimensional δ13C-δ15N space) of the Orange-throated whiptail (Aspidoscelis hyperythra), an arthropodivorous small lizard, in ten localities of Baja California Sur (Mexico). These localities range from extreme arid to subtropical conditions. Between 13 and 20 individuals were sampled at each locality and 1 cm of tail-tip was collected for isotope analysis. As expected, interpopulation niche width variation was much larger than intrapopulation one. Besides, isotopic variation was not related to age, sex or individual size of lizards. This suggests geographic variation of the isotopic niche was related to changes in the basal resources that fuel the trophic web at each locality. The position of Bayesian isotope ellipses in the δ-space indicated that whiptails in more arid localities were enriched in 13C, suggesting most of the carbon they ingested came from CAM succulent plants (cacti, agaves) and in minor degree in C4 grasses. Contrarily, whiptails in subtropical areas were depleted in 13C, as they received more carbon from C3 scrubs and trees. Localities closer to sea-level tended to be enriched in 15N, but a clear influence of marine subsidies was detected only at individual level. The study contributes to identify the origin and pathways through which energy flows across the trophic webs of North American deserts. PMID:25973609

  16. 78 FR 28000 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-05-13

    ... 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has... facilities and equipment. Location Antarctic Peninsula region, ASPA 117-Avian Island, ASPA 128 Cape...

  17. 78 FR 54686 - Notice of Permit Applications Received under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-09-05

    ... the Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism... of the ongoing effort to monitor the spatial scale of human impacts in Antarctica. Samples taken near...

  18. 77 FR 50720 - Notice of Permit Modification Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-08-22

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and..., bill and flipper dimensions taken, 3-5 feathers removed to confirm gender of the penguin, and have GPS...

  19. 78 FR 56743 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-09-13

    ... by the Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science... measure ablation and GPS units to monitor the motion of the glacier. The GPR system will be moved...

  20. 77 FR 67407 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-11-09

    ... designation of certain animals and certain geographic areas a requiring special protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas. The applications received... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic...

  1. 78 FR 56744 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-09-13

    ... requiring special protection. The regulations establish such a permit system to designate Antarctic... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 AGENCY: National Science Foundation. ACTION: Notice of Permit Applications Received...

  2. 77 FR 38834 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-06-29

    ... requiring special protection. The regulations establish such a permit system to designate Antarctic... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 AGENCY: National Science Foundation. ACTION: Notice of permit applications received...

  3. 78 FR 59728 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-09-27

    ... requiring special protection. The regulations establish such a permit system to designate Antarctic... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Foundation (NSF) is required to publish a notice of permit applications received to conduct activities...

  4. Potential of the solid-Earth response for limiting long-term West Antarctic Ice Sheet retreat

    Science.gov (United States)

    Konrad, Hannes; Sasgen, Ingo; Pollard, David; Klemann, Volker

    2016-04-01

    The West Antarctic Ice Sheet (WAIS) is assumed to be inherently unstable because it is grounded below sea level in a large part, where the bedrock deepens from today's grounding line towards the interior of the ice sheet. Idealized simulations have shown that bedrock uplift due to isostatic adjustment of the solid Earth and the associated sea-level fall may stop the retreat of such a marine-based ice sheet (Gomez et al., 2012). Here, we employ a coupled model for ice-sheet dynamics and solid-Earth dynamics, including a gravitationally consistent description of sea level, to investigate the influence of the viscoelastic Earth structure on the WAIS' future stability (Konrad et al. 2015). For this, we start from a steady-state condition for the Antarctic Ice Sheet close to present-day observations and apply atmospheric and oceanic forcing of different strength to initiate the retreat of the WAIS and investigate the effect of the viscoelastic deformation on the ice evolution for a range of solid-Earth rheologies. We find that the climate forcing is the primary control on the occurrence of the WAIS collapse. However, for moderate climate forcing and a weak solid-Earth rheology associated with the West Antarctic rift system (asthenosphere viscosities of 3x10^19 Pa s or less), we find that the combined effect of bedrock uplift and gravitational sea-level fall limits the retreat to the Amundsen Sea embayment on millennial time scales. In contrast, a stiffer Earth rheology yields a collapse under these conditions. Under a stronger climate forcing, weak Earth structures do not prevent the WAIS collapse; however, they produce a delay of up to 5000 years in comparison to a stiffer solid-Earth rheology. In an additional experiment, we test the impact of sea-level rise from an assumed fast deglaciation of the Greenland Ice Sheet. In cases when the climatic forcing is too weak to force WAIS collapse by itself, the additional rise in sea-level leads to disintegration of the WAIS

  5. Population dynamics of Salpa thompsoni near the Antarctic Peninsula: Growth rates and interannual variations in reproductive activity (1993-2009)

    Science.gov (United States)

    Loeb, V. J.; Santora, J. A.

    2012-04-01

    The salp Salpa thompsoni has exhibited increased abundance in high latitude portions of the Southern Ocean in recent decades and is now frequently the numerically dominant zooplankton taxon in the Antarctic Peninsula region. The abundance increase of this species in high latitude waters is believed related to ocean warming. Due to its continuous filter feeding and production of dense rapidly sinking fecal pellets S. thompsoni is considered to be an important link in the export of particulate carbon from the surface waters. Hence basic information on the life history of this component of the Antarctic marine ecosystem is essential for assessing its impact given continued climate warming. Here we cover various aspects of the life history of S. thompsoni collected in the north Antarctic Peninsula during annual austral summer surveys of the US Antarctic Marine Living Resources (AMLR) Program between 1993 and 2009. We focus on seasonal and interannual variations in the size composition and abundance of the aggregate (sexual) and solitary (asexual) stages. This information is valuable for refining components of Southern Ocean food web models that explicitly deal with size-structured and life history information on zooplankton. Intraseasonal changes in length-frequency distribution of both stages are used to estimate their growth rates. These average 0.40 mm day-1 for aggregates and 0.23 mm day-1 for solitaries; together these represent ∼7 week and ∼7.5 month generation times, respectively, and a 9 month life cycle (i.e., onset of aggregate production year 1 to aggregate production year 2). Based on the maximum lengths typically found during January-March, the life spans of the aggregate and solitary stages can reach at least ∼5 and ∼15 months, respectively. Length-frequency distributions each year reflect interannual differences in timing of the initiation and peak reproductive output. Interannual differences in the abundance of total salps and proportions of the

  6. The not-so-silent world: Measuring Arctic, Equatorial, and Antarctic soundscapes in the Atlantic Ocean

    Science.gov (United States)

    Haver, Samara M.; Klinck, Holger; Nieukirk, Sharon L.; Matsumoto, Haru; Dziak, Robert P.; Miksis-Olds, Jennifer L.

    2017-04-01

    Anthropogenic noise in the ocean has been shown, under certain conditions, to influence the behavior and health of marine mammals. Noise from human activities may interfere with the low-frequency acoustic communication of many Mysticete species, including blue (Balaenoptera musculus) and fin whales (B. physalus). This study analyzed three soundscapes in the Atlantic Ocean, from the Arctic to the Antarctic, to document ambient sound. For 16 months beginning in August 2009, acoustic data (15-100 Hz) were collected in the Fram Strait (79°N, 5.5°E), near Ascension Island (8°S, 14.4°W) and in the Bransfield Strait (62°S, 55.5°W). Results indicate (1) the highest overall sound levels were measured in the equatorial Atlantic, in association with high levels of seismic oil and gas exploration, (2) compared to the tropics, ambient sound levels in polar regions are more seasonally variable, and (3) individual elements beget the seasonal and annual variability of ambient sound levels in high latitudes. Understanding how the variability of natural and man-made contributors to sound may elicit differences in ocean soundscapes is essential to developing strategies to manage and conserve marine ecosystems and animals.

  7. Persistence of Antarctic polar stratospheric clouds

    Science.gov (United States)

    Mccormick, M. Patrick; Trepte, C. R.

    1988-01-01

    The persistence of Polar Stratospheric Clouds (PSCs) observed by the Stratospheric Aerosol Measurement (SAM) 2 satellite sensor over a 9-year period is compared and contrasted. Histograms of the SAM 2 1.0 micron extinction ratio data (aerosol extinction normalized by the molecular extinction) at an altitude of 18 km in the Antarctic have been generated for three 10-day periods in the month of September. Statistics for eight different years (1979 to 1982 and 1984 to 1987) are shown in separate panels for each figure. Since the SAM 2 system is a solar occultation experiment, observations are limited to the edge of the polar night and no measurements are made deep within the vortex where temperatures could be colder. For this reason, use is made of the NMC global gridded fields and the known temperature-extinction relationship to infer additional information on the occurrence and areal coverage of PSCs. Calculations of the daily areal coverage of the 195 K isotherm will be presented for this same period of data. This contour level lies in the range of the predicted temperature for onset of the Type 1 particle enhancement mode at 50 mb (Poole and McCormick, 1988b) and should indicate approximately when formation of the binary HNO3-H2O particles begins.

  8. Peripheral cold acclimatization in Antarctic scuba divers.

    Science.gov (United States)

    Bridgman, S A

    1991-08-01

    Peripheral acclimatization to cold in scuba divers stationed at the British Antarctic Survey's Signy Station was investigated during a year in Antarctica. Five divers and five non-diver controls underwent monthly laboratory tests of index finger immersion in cold water for 30 min. Index finger pulp temperature and time of onset of cold-induced vasodilatation (CIVD) were measured. Pain was recorded with verbal and numerical psychophysical subjective pain ratings. Average finger temperatures and median finger pain from 6-30 min of immersion, maximum finger temperatures during the first CIVD cycle, and finger temperatures at the onset of CIVD were calculated. Comparison of the variables recorded from divers and non-divers were performed with analysis of variance. No significant differences were found among the variables recorded from divers and non-divers. From a review of the literature, divers have responses typical of non-cold-adapted Caucasians. There is, therefore, no evidence that Signy divers peripherally acclimatized to cold. We suggest that these findings occur because either the whole body cooling which divers undergo inhibits peripheral acclimatization or because of insufficiently frequent or severe cold exposure while diving. Further basic studies on the duration, frequency and severity of cold exposure necessary to induce peripheral cold acclimatization are required before this question can be satisfactorily answered.

  9. Antarctic icebergs distributions 1992-2014

    Science.gov (United States)

    Tournadre, J.; Bouhier, N.; Girard-Ardhuin, F.; Rémy, F.

    2016-01-01

    Basal melting of floating ice shelves and iceberg calving constitute the two almost equal paths of freshwater flux between the Antarctic ice cap and the Southern Ocean. The largest icebergs (>100 km2) transport most of the ice volume but their basal melting is small compared to their breaking into smaller icebergs that constitute thus the major vector of freshwater. The archives of nine altimeters have been processed to create a database of small icebergs (law of slope -1.52 ± 0.32 close to the -3/2 laws observed and modeled for brittle fragmentation. The global volume of ice and its distribution between the ocean basins present a very strong interannual variability only partially explained by the number of large icebergs. Indeed, vast zones of the Southern Ocean free of large icebergs are largely populated by small iceberg drifting over thousands of kilometers. The correlation between the global small and large icebergs volumes shows that small icebergs are mainly generated by large ones breaking. Drifting and trapping by sea ice can transport small icebergs for long period and distances. Small icebergs act as an ice diffuse process along large icebergs trajectories while sea ice trapping acts as a buffer delaying melting.

  10. 78 FR 41959 - Notice of Permit Modification Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-07-12

    ... Areas (ASPA) or involving Antarctic Flora and Fauna. Starting in 2013, all new permits issued for ASPA entry or involving Antarctic Flora and Flora require the permittee to submit an annual report to the... Specially Protected Areas (ASPA) or involving Antarctic Flora and Fauna issued prior to 2013 that require...

  11. 77 FR 41809 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-07-16

    ..., Lockheed Martin IS&GS, Antarctic Support Contract, 7400 S. Tucson Way, Centennial, CO 80112-3938. Activity..., Antarctic Support Contract, 7400 S. Tucson Way, Centennial, CO 80112-3938. Activity for Which Permit Is.... Applicant: Celia Lang, Lockheed Martin IS&GS, Antarctic Support Contract, 7400 S. Tucson Way, Centennial, CO...

  12. Feasibility of Using Alternate Fuels in the U.S. Antarctic Program: Initial Assessment

    Science.gov (United States)

    2017-09-01

    Polar Programs. Morris, A. 2015a. Email communication. 21 April. Centennial , CO: Antarctic Support Contractor. ———. 2015b. Personal...communication. 19 May. Centennial , CO: Antarctic Support Contractor. ———. 2014. Email communication. 24 November. Centennial , CO: Antarctic Support

  13. Biodiversity: invasions by marine life on plastic debris.

    Science.gov (United States)

    Barnes, David K A

    2002-04-25

    Colonization by alien species poses one of the greatest threats to global biodiversity. Here I investigate the colonization by marine organisms of drift debris deposited on the shores of 30 remote islands from the Arctic to the Antarctic (across all oceans) and find that human litter more than doubles the rafting opportunities for biota, particularly at high latitudes. Although the poles may be protected from invasion by freezing sea surface temperatures, these may be under threat as the fastest-warming areas anywhere are at these latitudes.

  14. Active Marine Station Metadata

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Active Marine Station Metadata is a daily metadata report for active marine bouy and C-MAN (Coastal Marine Automated Network) platforms from the National Data...

  15. Biodiversity of Antarctic echinoids: a comprehensive and interactive database

    Directory of Open Access Journals (Sweden)

    Bruno David

    2005-12-01

    Full Text Available Eighty-one echinoid species are present south of the Antarctic Convergence, and they represent an important component of the benthic fauna. “Antarctic echinoids” is an interactive database synthesising the results of more than 100 years of Antarctic expeditions, and comprising information about all echinoid species. It includes illustrated keys for determination of the species, and information about their morphology and ecology (text, illustrations and glossary and their distribution (maps and histograms of bathymetrical distribution; the sources of the information (bibliography, collections and expeditions are also provided. All these data (taxonomic, morphologic, geographic, bathymetric… can be interactively queried in two main ways: (1 display of listings that can be browsed, sorted according to various criteria, or printed; and (2 interactive requests crossing the different kinds of data. Many other possibilities are offered, and an on-line help file is also available.

  16. Potential sea-level rise from Antarctic ice-sheet instability constrained by observations

    Science.gov (United States)

    Ritz, Catherine; Edwards, Tamsin L.; Durand, Gaël; Payne, Antony J.; Peyaud, Vincent; Hindmarsh, Richard C. A.

    2015-12-01

    Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive to generate large ensembles for uncertainty assessment, and lower-resolution model projections rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.

  17. Bacterial succession across seasonal transitions in the coastal waters of the western Antarctic Peninsula

    Science.gov (United States)

    Luria, C.; Rich, J. J.; Amaral-Zettler, L. A.; Ducklow, H. W.

    2016-02-01

    The marine ecosystem west of the Antarctic Peninsula (WAP) undergoes a dramatic seasonal transition every spring, from almost total darkness to almost continuous sunlight, resulting in a cascade of environmental changes, including the intense phytoplankton blooms that support a highly productive food web. Despite having important implications for the microbial loop and the biological carbon pump, the degree of trophic coupling between phytoplankton and bacteria is unclear. In particular, due to the difficulties inherent in sampling this remote system during the Antarctic winter and spring, little is known about how phytoplankton blooms may or may not drive bacterial seasonal succession. Using 16S rRNA gene amplicon sequencing, we assessed bacterial community composition in 68 samples from 24 dates that spanned the cold, dark winter, spring transitional period, and summer phytoplankton bloom. Our analysis resulted in 15 million sequences and 12,000 Operational Taxonomic Units (OTUs). We found that mid-winter bacterial communities had the highest richness ( 1,800 observed OTUs in rarefied libraries) and a greater abundance of oligotrophic and potentially chemoautolithotrophic taxa. The bacterial community changed only gradually up until the onset of a mid-summer phytoplankton bloom, which coincided with a 100-fold increase in bacterial production, a rapid decline in richness to 700 OTUs, and a shift in community composition toward copiotrophic taxa. This period lasted only a few weeks, at the end of which the bacterial community had largely reverted to its mid-winter state. Our findings provide new evidence of trophic coupling between bacteria and phytoplankton and highlight the importance of higher-resolution time series sampling in order to capture rapid seasonal changes.

  18. Characterization of Stearoyl-CoA Desaturases from a Psychrophilic Antarctic Copepod, Tigriopus kingsejongensis.

    Science.gov (United States)

    Jung, Woongsic; Kim, Eun Jae; Han, Se Jong; Choi, Han-Gu; Kim, Sanghee

    2016-10-01

    Stearoyl-CoA desaturase is a key regulator in fatty acid metabolism that catalyzes the desaturation of stearic acid to oleic acid and controls the intracellular levels of monounsaturated fatty acids (MUFAs). Two stearoyl-CoA desaturases (SCD, Δ9 desaturases) genes were identified in an Antarctic copepod, Tigriopus kingsejongensis, that was collected in a tidal pool near the King Sejong Station, King George Island, Antarctica. Full-length complementary DNA (cDNA) sequences of two T. kingsejongensis SCDs (TkSCDs) were obtained from next-generation sequencing and isolated by reverse transcription PCR. DNA sequence lengths of the open reading frames of TkSCD-1 and TkSCD-2 were determined to be 1110 and 681 bp, respectively. The molecular weights deduced from the corresponding genes were estimated to be 43.1 kDa (TkSCD-1) and 26.1 kDa (TkSCD-2). The amino acid sequences were compared with those of fatty acid desaturases and sterol desaturases from various organisms and used to analyze the relationships among TkSCDs. As assessed by heterologous expression of recombinant proteins in Escherichia coli, the enzymatic functions of both stearoyl-CoA desaturases revealed that the amount of C16:1 and C18:1 fatty acids increased by greater than 3-fold after induction with isopropyl β-D-thiogalactopyranoside. In particular, C18:1 fatty acid production increased greater than 10-fold in E. coli expressing TkSCD-1 and TkSCD-2. The results of this study suggest that both SCD genes from an Antarctic marine copepod encode a functional desaturase that is capable of increasing the amounts of palmitoleic acid and oleic acid in a prokaryotic expression system.

  19. An Ensemble Analysis of Antarctic Glacial Isostatic Adjustment and Sea Level

    Science.gov (United States)

    Lecavalier, B.; Tarasov, L.

    2016-12-01

    Inferences of past ice sheet evolution that lack any uncertainty assessment (implicit or explicit), have little value. A developing technique for explicit uncertainty quantification of glacial systems is Bayesian calibration of models against large observational data-sets (Tarasov et al., 2012). The foundation for a Bayesian calibration of a 3D glacial systems model (GSM) for Antarctica has recently been completed (Briggs et al., 2013; 2014; Briggs and Tarasov, 2013). Bayesian calibration thoroughly samples model uncertainties against fits to observational data to generate a probability distribution for the Antarctic Ice Sheet deglaciation with explicit and well-defined confidence intervals. To have validity as a complete inference of past ice sheet evolution, Bayesian calibration requires a model that "brackets reality".Past work has shown the GSM to have likely inadequate range of grounding line migration in certain sectors as well as persistent ice thickness biases in topographically complex regions (Briggs et al., 2014). To advance towards full calibration, these deficiencies are being addressed through a number of model developments. The grounding line scheme has been revised (Pollard and DeConto, 2012), the horizontal resolution is increased to 20 km, and boundary conditions are updated. The basal drag representation now includes the sub-grid treatment of the thermo-mechanical impacts of high basal roughness. Parametric uncertainties in basal drag for regions that are presently marine have been re-evaluated. The impact of past changes in ocean temperature on sub ice shelf melt is explicitly incorporated in the current ocean forcing parametric scheme. Uncertainties in earth rheology are also probed to robustly quantify uncertainties affiliated with glacial isostatic adjustment. The ensemble analysis of the Antarctic glacial system provides dynamical bounds on past and present Antarctica glacial isostatic adjustment and sea level contributions. This research

  20. Emperors in hiding: when ice-breakers and satellites complement each other in Antarctic exploration.

    Directory of Open Access Journals (Sweden)

    André Ancel

    Full Text Available Evaluating the demographic trends of marine top predators is critical to understanding the processes involved in the ongoing rapid changes in Antarctic ecosystems. However, the remoteness and logistical complexity of operating in Antarctica, especially during winter, make such an assessment difficult. Satellite imaging is increasingly recognised as a valuable method for remote animal population monitoring, yet its accuracy and reliability are still to be fully evaluated. We report here the first ground visit of an emperor penguin colony first discovered by satellite, but also the discovery of a second one not indicated by satellite survey at that time. Several successive remote surveys in this coastal region of East Antarctica, both before and after sudden local changes, had indeed only identified one colony. These two colonies (with a total of ca. 7,400 breeding pairs are located near the Mertz Glacier in an area that underwent tremendous habitat change after the glacier tongue broke off in February 2010. Our findings therefore suggest that a satellite survey, although offering a major advance since it allows a global imaging of emperor penguin colonies, may miss certain colony locations when challenged by certain features of polar ecosystems, such as snow cover, evolving ice topology, and rapidly changing habitat. Moreover our survey shows that this large seabird has considerable potential for rapid adaptation to sudden habitat loss, as the colony detected in 2009 may have moved and settled on new breeding grounds. Overall, the ability of emperor penguin colonies to relocate following habitat modification underlines the continued need for a mix of remote sensing and field surveys (aerial photography and ground counts, especially in the less-frequented parts of Antarctica, to gain reliable knowledge about the population demography and dynamics of this flagship species of the Antarctic ecosystem.

  1. Emperors in hiding: when ice-breakers and satellites complement each other in Antarctic exploration.

    Science.gov (United States)

    Ancel, André; Cristofari, Robin; Fretwell, Peter T; Trathan, Phil N; Wienecke, Barbara; Boureau, Matthieu; Morinay, Jennifer; Blanc, Stéphane; Le Maho, Yvon; Le Bohec, Céline

    2014-01-01

    Evaluating the demographic trends of marine top predators is critical to understanding the processes involved in the ongoing rapid changes in Antarctic ecosystems. However, the remoteness and logistical complexity of operating in Antarctica, especially during winter, make such an assessment difficult. Satellite imaging is increasingly recognised as a valuable method for remote animal population monitoring, yet its accuracy and reliability are still to be fully evaluated. We report here the first ground visit of an emperor penguin colony first discovered by satellite, but also the discovery of a second one not indicated by satellite survey at that time. Several successive remote surveys in this coastal region of East Antarctica, both before and after sudden local changes, had indeed only identified one colony. These two colonies (with a total of ca. 7,400 breeding pairs) are located near the Mertz Glacier in an area that underwent tremendous habitat change after the glacier tongue broke off in February 2010. Our findings therefore suggest that a satellite survey, although offering a major advance since it allows a global imaging of emperor penguin colonies, may miss certain colony locations when challenged by certain features of polar ecosystems, such as snow cover, evolving ice topology, and rapidly changing habitat. Moreover our survey shows that this large seabird has considerable potential for rapid adaptation to sudden habitat loss, as the colony detected in 2009 may have moved and settled on new breeding grounds. Overall, the ability of emperor penguin colonies to relocate following habitat modification underlines the continued need for a mix of remote sensing and field surveys (aerial photography and ground counts), especially in the less-frequented parts of Antarctica, to gain reliable knowledge about the population demography and dynamics of this flagship species of the Antarctic ecosystem.

  2. Submarine geology and geomorphology of active Sub-Antarctic volcanoes: Heard and McDonald Islands

    Science.gov (United States)

    Watson, S. J.; Coffin, M. F.; Whittaker, J. M.; Lucieer, V.; Fox, J. M.; Carey, R.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Martin, T.; Cooke, F.

    2016-12-01

    Heard and McDonald Islands (HIMI) are World Heritage listed sub-Antarctic active volcanic islands in the Southern Indian Ocean. Built atop the Kerguelen Plateau by Neogene-Quaternary volcanism, HIMI represent subaerial exposures of the second largest submarine Large Igneous Province globally. Onshore, processes influencing island evolution include glaciers, weathering, volcanism, vertical tectonics and mass-wasting (Duncan et al. 2016). Waters surrounding HIMI are largely uncharted, due to their remote location. Hence, the extent to which these same processes shape the submarine environment around HIMI has not been investigated. In early 2016, we conducted marine geophysical and geologic surveys around HIMI aboard RV Investigator (IN2016_V01). Results show that volcanic and sedimentary features prominently trend east-west, likely a result of erosion by the eastward flowing Antarctic Circumpolar Current and tidal currents. However, spatial patterns of submarine volcanism and sediment distribution differ substantially between the islands. >70 sea knolls surround McDonald Island suggesting substantial submarine volcanism. Geophysical data reveals hard volcanic seafloor around McDonald Island, whereas Heard Island is characterised by sedimentary sequences tens of meters or more thick and iceberg scours - indicative of glacial processes. Differences in submarine geomorphology are likely due to the active glaciation of Heard Island and differing rock types (Heard: alkali basalt, McDonald: phonolite), and dominant products (clastics vs. lava). Variations may also reflect different magmatic plumbing systems beneath the two active volcanoes (Heard produces larger volumes of more focused lava, whilst McDonald extrudes smaller volumes of more evolved lavas from multiple vents across the edifice). Using geophysical data, corroborated with new and existing geologic data, we present the first geomorphic map revealing the processes that shape the submarine environment around HIMI.

  3. Evidence for a dynamic East Antarctic ice sheet during the mid-Miocene climate transition

    Science.gov (United States)

    Pierce, Elizabeth L.; van de Flierdt, Tina; Williams, Trevor; Hemming, Sidney R.; Cook, Carys P.; Passchier, Sandra

    2017-11-01

    The East Antarctic ice sheet underwent a major expansion during the Mid-Miocene Climate Transition, around 14 Ma, lowering sea level by ∼60 m. However, direct or indirect evidence of where changes in the ice sheet occurred is limited. Here we present new insights on timing and locations of ice sheet change from two drill sites offshore East Antarctica. IODP Site U1356, Wilkes Land, and ODP Site 1165, Prydz Bay are located adjacent to two major ice drainage areas, the Wilkes Subglacial Basin and the Lambert Graben. Ice-rafted detritus (IRD), including dropstones, was deposited in concentrations far exceeding those known in the rest of the Miocene succession at both sites between 14.1 and 13.8 Ma, indicating that large amounts of IRD-bearing icebergs were calved from independent drainage basins during this relatively short interval. At Site U1356, the IRD was delivered in distinct pulses, suggesting that the overall ice advance was punctuated by short periods of ice retreat in the Wilkes Subglacial Basin. Provenance analysis of the mid-Miocene IRD and fine-grained sediments provides additional insights on the movement of the ice margin and subglacial geology. At Site U1356, the dominant 40Ar/39Ar thermochronological age of the ice-rafted hornblende grains is 1400-1550 Ma, differing from the majority of recent IRD in the area, from which we infer an inland source area of this thermochronological age extending along the eastern part of the Adélie Craton, which forms the western side of the Wilkes Subglacial Basin. Neodymium isotopic compositions from the terrigenous fine fraction at Site U1356 imply that the ice margin periodically expanded from high ground well into the Wilkes Subglacial Basin during periods of MMCT ice growth. At Site 1165, MMCT pebble-sized IRD are sourced from both the local Lambert Graben and the distant Aurora Subglacial Basin drainage area. Together, the occurrence and provenance of the IRD and glacially-eroded sediment at these two marine

  4. Marine Sciences

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    PNL research in the marine sciences is focused on establishing a basic understanding of the mechanisms of stress and tolerance in marine organisms exposed to contaminants. Several environmental stressors had been investigated in earlier energy-related research. In a landmark study, for example, PNL had established that the severity of fish disease caused by the common infectious agent, Flexobacter columnaris, was seriously aggravated by thermal enhancement and certain ecological factors. Subsequent studies demonstrated that the primary immune response in fish, challenged by columnaris, could be permanently suppressed by comparatively low tritium exposures. The research has suggested that a potential exists for a significant biological impact when an aquatic stressor is added to an ambient background of other stressors, which may include heat, heavy metal ions, radiation or infectious microorganisms. More recently, PNL investigators have shown that in response to heavy metal contaminants, animals synthesize specific proteins (metallothioneins), which bind and sequester metals in the animals, thus decreasing metal mobility and effects. Companion studies with host-specific intracellular pathogens are being used to investigate the effects of heavy metals on the synthesis of immune proteins, which mitigate disease processes. The results of these studies aid in predicting the ecological effects of energy-related contaminants on valued fin and shellfish species

  5. Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea ice

    Directory of Open Access Journals (Sweden)

    R. S. Humphries

    2016-02-01

    Full Text Available Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3 concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between

  6. Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea ice

    Science.gov (United States)

    Humphries, R. S.; Klekociuk, A. R.; Schofield, R.; Keywood, M.; Ward, J.; Wilson, S. R.

    2016-02-01

    Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm-3 - higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of

  7. In vitro immunobiological activity of an Antarctic streptomyces polysaccharide

    International Nuclear Information System (INIS)

    Toshkova, R.; Yossifova, L.; Gardeva, E.; Zvetkova, E.; Ivanova, V.

    2010-01-01

    Antarctic Streptomyces sp. 1010, were obtained from sea water samples (Livingston Island, Antarctica), during the Third Bulgarian Antarctic Scientific Expedition (1994-1995). The ecophysiological methods for isolation and characterization of these active, cold-adapted, Gram-positive microorganisms (psychrophiles) in morphological, phenotypic, genetic and taxonomic aspects, have been earlier reported. In this study, a new extracellular polysaccharide (heteropolysaccharide) has been isolated and purified from cultured broth of the Antarctic Streptomyces sp. 1010. The monosaccharide content of the Antarctic streptomyces heteropolysaccharide has been examined by TLC and GC/MS. The mitogenic and immuno potential properties of the purified Antarctic Streptomyces polysaccharide (ASMP) have been studied in vitro - in the short-term cultures of human peripheral blood mononuclear cells (hPBMCs - lymphocytes and monocytes) and mouse spleen lymphocytes (mouse splenocytes - mSps). The results obtained show that ASMP has a double lectin-like effect on the proliferative activity of hPBMCs: similar to this of Con A on the lymphoid cells (preliminary T-lymphocytes) and to the effect of LPS on the mononuclear from monocyte-macrophage lineage. Expressed as proliferative index (PI), the mitogenic response of mSps to the in vitro influence of ASMP was also higher than PI in the negative, as well as in the positive controls (mSps, cultured in the presence of PHA, Con A and LPS). The new Antarctic Streptomyces' heteropolysaccharide examined could be useful in the future as an immunomodulative biologically active substance and its extracellular production may contribute to the development of thermobiochemistry, immunomodulative drug therapy and immunopharmaceutical industry. (authors)

  8. Exploration of low temperature microRNA function in an anoxia tolerant vertebrate ectotherm, the red eared slider turtle (Trachemys scripta elegans).

    Science.gov (United States)

    Biggar, Kyle K; Storey, Kenneth B

    2017-08-01

    As a model for vertebrate long-term survival in oxygen-restricted environments, the red-eared slider turtle (Trachemys scripta elegans) can adapt at the biochemical level to survive in oxygen-free (anoxic) cold water (<10°C). This impressive ability is enabled through a coordinated suppression of energy-expensive, non-essential, cell processes. This study explored the anoxia-responsive expression of several microRNA species (miR-1a, -133, -17, -107, -148a, -21, -103, -210, -20a, -365 and -29b) in adult turtles exposed to 5h and 20h anoxia (at 5±1°C). Furthermore, since microRNA target binding is regularly defined only by microRNA-mRNA interactions at 37°C, the possibility of unique low temperature-selective microRNA targeting interactions with mRNA was explored in this ectotherm. Approximately twice as many microRNA-mRNA interactions were predicted at 5°C versus 37°C with particular enrichment of mRNA targets involved in biological processes known to be part of the stress response. Hence, the results suggest that the influence of temperature should be considered for the prediction of microRNA targets (and their follow-up) in poikilothermic animals and that interacting effects of low body temperature and anoxia on microRNA expression could potentially be important to achieve the profound metabolic rate depression that characterizes turtle hibernation underwater during the winter. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Spatial-temporal variations in surface ozone over Ushuaia and the Antarctic region: observations from in situ measurements, satellite data, and global models.

    Science.gov (United States)

    Nadzir, Mohd Shahrul Mohd; Ashfold, Matthew J; Khan, Md Firoz; Robinson, Andrew D; Bolas, Conor; Latif, Mohd Talib; Wallis, Benjamin M; Mead, Mohammed Iqbal; Hamid, Haris Hafizal Abdul; Harris, Neil R P; Ramly, Zamzam Tuah Ahmad; Lai, Goh Thian; Liew, Ju Neng; Ahamad, Fatimah; Uning, Royston; Samah, Azizan Abu; Maulud, Khairul Nizam; Suparta, Wayan; Zainudin, Siti Khalijah; Wahab, Muhammad Ikram Abdul; Sahani, Mazrura; Müller, Moritz; Yeok, Foong Swee; Rahman, Nasaruddin Abdul; Mujahid, Aazani; Morris, Kenobi Isima; Sasso, Nicholas Dal

    2018-01-01

    The Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O 3 ) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC'16). Hourly O 3 data was measured continuously for 23 days using an EcoTech O 3 analyzer. To understand more about the distribution of surface O 3 over the Antarctic, we present the spatial and temporal of surface O 3 of long-term data (2009-2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furthermore, surface O 3 satellite data from the free online NOAA-Atmospheric Infrared Sounder (AIRS) database and online data assimilation from the European Centre for Medium-Range Weather Forecasts (ECMWF)-Monitoring Atmospheric Composition and Climate (MACC) were used. The data from both online products are compared to document the data sets and to give an indication of its quality towards in situ data. Finally, we used past carbon monoxide (CO) data as a proxy of surface O 3 formation over Ushuaia and the Antarctic region. Our key findings were that the surface O 3 mixing ratio during MASEC'16 increased from a minimum of 5 ppb to ~ 10-13 ppb approaching the Drake Passage and the Coastal Antarctic Peninsula (CAP) region. The anthropogenic and biogenic O 3 precursors from Ushuaia and the marine region influenced the mixing ratio of surface O 3 over the Drake Passage and CAP region. The past data from WDCGG showed that the annual O 3 cycle has a maximum during the winter of 30 to 35

  10. Extensive lake sediment coring survey on Sub-Antarctic Indian Ocean Kerguelen Archipelago (French Austral and Antarctic Lands)

    Science.gov (United States)

    Arnaud, Fabien; Fanget, Bernard; Malet, Emmanuel; Poulenard, Jérôme; Støren, Eivind; Leloup, Anouk; Bakke, Jostein; Sabatier, Pierre

    2016-04-01

    Recent paleo-studies revealed climatic southern high latitude climate evolution patterns that are crucial to understand the global climate evolution(1,2). Among others the strength and north-south shifts of westerlies wind appeared to be a key parameter(3). However, virtually no lands are located south of the 45th South parallel between Southern Georgia (60°W) and New Zealand (170°E) precluding the establishment of paleoclimate records of past westerlies dynamics. Located around 50°S and 70°E, lost in the middle of the sub-Antarctic Indian Ocean, Kerguelen archipelago is a major, geomorphologically complex, land-mass that is covered by hundreds lakes of various sizes. It hence offers a unique opportunity to reconstruct past climate and environment dynamics in a region where virtually nothing is known about it, except the remarkable recent reconstructions based on a Lateglacial peatbog sequence(4). During the 2014-2015 austral summer, a French-Norwegian team led the very first extensive lake sediment coring survey on Kerguelen Archipelago under the umbrella of the PALAS program supported by the French Polar Institute (IPEV). Two main areas were investigated: i) the southwest of the mainland, so-called Golfe du Morbihan, where glaciers are currently absent and ii) the northernmost Kerguelen mainland peninsula so-called Loranchet, where cirque glaciers are still present. This double-target strategy aims at reconstructing various independent indirect records of precipitation (glacier advance, flood dynamics) and wind speed (marine spray chemical species, wind-borne terrigenous input) to tackle the Holocene climate variability. Despite particularly harsh climate conditions and difficult logistics matters, we were able to core 6 lake sediment sites: 5 in Golfe du Morbihan and one in Loranchet peninsula. Among them two sequences taken in the 4km-long Lake Armor using a UWITEC re-entry piston coring system by 20 and 100m water-depth (6 and 7m-long, respectively). One

  11. 222Rn in the Antarctic Peninsula during 1986

    International Nuclear Information System (INIS)

    Pereira, E.B.; Setzer, A.W.; Cavalcanti, I.F.A.

    1988-01-01

    222 Rn was continuously measured at the Brazilian Antarctic Station (62 0 S, 58 0 W) during the year of 1986. Baseline radon concentration averaged 0.02 Bq.m -3 with surges peaking 0.4 Bq.m -3 . The data exhibited a characteristic periodicity of about 25 days and a strong positive association with short term fluctuations of atmospheric temperature. No seasonal variations of radon were observed. Interpretation of the radon surges with reference to synoptic charts and weather satellite pictures showed that the continental influence of radon at the Antarctic Peninsula is very small and comes only from the tip of the South American cone. (author)

  12. Microbiology and Geochemistry of Antarctic Paleosols

    Science.gov (United States)

    Mahaney, W. C.; Malloch, D.; Hancock, R. G. V.; Campbell, I. B.; Sheppard, D.

    2000-08-01

    Samples of ancient soils from horizons in paleosols from the Quartermain Mountains (Aztec and New Mountain areas of the Antarctic Dry Valleys) were analyzed for their chemical composition and microbiology to determine the accumulation and movement of salts and other soluble constituents. The salt concentrations are of special interest because they are considered to be a function of age, derived in part from nearby oceanic and high altitude atmospheric sources. The geochemistry of ancient Miocene-age paleosols in these areas is the direct result of the deposition and weathering of till, derived principally from dolerite and sandstone source rock, in association with airborne-influxed salts. Paleosols nearer the coast have greater contents of chlorine, and farther inland near the Inland Ice Sheet, nitrogen tends to increase on a relative basis. The accumulation and vertical distribution of salts and other soluble chemical elements indicate relative amounts of movement in the profile over long periods of time, to the order of several million years. Iron, both in total concentration and in the form of various extracts, indicates it can be used as a geochronometer to assess the buildup of goethite plus hematite over time in the paleosols. Trends for ferrihydrite, a partially soluble Fe-hydroxide, shows limited profile translocation that might be related to the movement of salt. Six of the eight selected subsamples from paleosol horizons in three soil profiles contained nil concentrations of bacteria and fungi. However, two horizons at depths of between three to eight centimeters yielded several colonies of the fungi Beauveria bassiana and Penicillium spp., indicating some input of organic carbon. Beauveria bassiana is often reported in association with insects and is used commercially for the biological control of some insect pests. Penicillium species are commonly isolated from Arctic, temperate and tropical soils and are known to utilize a wide variety of organic

  13. Antarctic volcanoes: A remote but significant hazard

    Science.gov (United States)

    Geyer, Adelina; Martí, Alex; Folch, Arnau; Giralt, Santiago

    2017-04-01

    Ash emitted during explosive volcanic eruptions can be dispersed over massive areas of the globe, posing a threat to both human health and infrastructures, such as the air traffic. Some of the last eruptions occurred during this decade (e.g. 14/04/2010 - Eyjafjallajökull, Iceland; 24/05/2011-Grímsvötn, Iceland; 05/06/2011-Puyehue-Cordón Caulle, Chile) have strongly affected the air traffic in different areas of the world, leading to economic losses of billions of euros. From the tens of volcanoes located in Antarctica, at least nine are known to be active and five of them have reported volcanic activity in historical times. However, until now, no attention has been paid to the possible social, economical and environmental consequences of an eruption that would occur on high southern latitudes, perhaps because it is considered that its impacts would be minor or local, and mainly restricted to the practically inhabited Antarctic continent. We show here, as a case study and using climate models, how volcanic ash emitted during a regular eruption of one of the most active volcanoes in Antarctica, Deception Island (South Shetland Islands), could reach the African continent as well as Australia and South America. The volcanic cloud could strongly affect the air traffic not only in the region and at high southern latitudes, but also the flights connecting Africa, South America and Oceania. Results obtained are crucial to understand the patterns of volcanic ash distribution at high southern latitudes with obvious implications for tephrostratigraphical and chronological studies that provide valuable isochrones with which to synchronize palaeoclimate records. This research was partially funded by the MINECO grants VOLCLIMA (CGL2015-72629-EXP)and POSVOLDEC(CTM2016-79617-P)(AEI/FEDER, UE), the Ramón y Cajal research program (RYC-2012-11024) and the NEMOH European project (REA grant 34 agreement n° 289976).

  14. Observation of hydro-acoustic signal from the Balleny Islands, Ross Sea, Antarctic: Seasonal ice activities and earthquakes from Pacific-Antarctic ridge

    Science.gov (United States)

    Hong, J. K.; Kang, S. G.; Dziak, R. P.; Park, Y.; Lau, T. K. A.; Haxel, J.; Matsumoto, H.

    2017-12-01

    From January 2015 to March 2016, five hydrophone moorings were deployed near the Balleny Islands to obtain the long-term hydroacoustic record as a collaborative effort between the NOAA/Pacific Marine Environmental Laboratory and the Korea Polar Research Institute. The goal of this hydro-acoustic project is to understand seasonal sea-ice activities and identify potential underwater volcanic sources within the Balleny seamounts. All five of the hydrophone moorings were recovered in March 2016, however only three of them recorded 14 months of continuous, broadband (1 kHz sample rate) hydro-acoustic data successfully. In spite of coordinating problem by partial recovery, recorded data contain valuable information for seasonal sea-ice activities and earthquakes from Pacific-Antarctic Ridge. We analyzed events from ice-quakes and earthquakes statistically. The number of ice-quakes is maximum in the austral summer while minimum in the austral winter which shows a clear seasonal pattern consistent with freeze-thaw cycles. Comparing with global earthquakes catalogue, number of earthquake events are correlated well with the catalogue. Because the austral winter is more calm by ice-quakes, however, we can detect more earthquakes in this season.

  15. Asynchronous behavior of the Antarctic Ice Sheet and local glaciers during and since Termination 1, Salmon Valley, Antarctica

    Science.gov (United States)

    Jackson, Margaret S.; Hall, Brenda L.; Denton, George H.

    2018-01-01

    The stability of the Antarctic Ice Sheet under future warming remains an open question with broad implications for sea-level prediction and adaptation. In particular, knowledge of whether the ice sheet has the capacity for rapid drawdown or collapse, or whether it can remain stable during periods of warming, is essential for predicting its future behavior. Here we use 55 radiocarbon dates, coupled with geomorphologic mapping, to reconstruct the timing of changes in ice extent and elevation during the last ice-age termination in Salmon Valley, adjacent to McMurdo Sound in the western Ross Sea Embayment. Results indicate that a grounded ice sheet in the Ross Sea Embayment achieved its maximum elevation and extent along the headlands of Salmon Valley at ∼18,000 yr BP, during a period of increasing temperatures and accumulation over the Antarctic continent. This ice remained at or near its maximum on the headlands near the valley mouth until after ∼14,000 yr BP. Removal of grounded Ross Sea ice from Salmon Valley was complete shortly after ∼7900 yr BP, indicating that the grounding line had retreated through southern McMurdo Sound by that time. We suggest the primary driver of Ross Sea ice removal from McMurdo Sound was marine-based, either through basal melting or calving due to sea-level rise. When combined with regional data, the Salmon Valley record suggests that this sector of the Antarctic Ice Sheet did not contribute in a significant way to deglacial meltwater pulses, such as meltwater pulse 1a. In contrast to the Ross Sea ice, our work also shows that local, independent alpine glaciers in Salmon Valley have advanced through the Holocene. Land-terminating glaciers such as these elsewhere in the region show a similar pattern, and may reflect the continued influence of increased accumulation following the termination of the last ice age.

  16. Persistent organohalogen contaminant burdens in Antarctic krill (Euphausia superba) from the eastern Antarctic sector: A baseline study

    International Nuclear Information System (INIS)

    Bengtson Nash, S.M.; Poulsen, A.H.; Kawaguchi, S.; Vetter, W.; Schlabach, M.

    2008-01-01

    A baseline for persistent organohalogen compound (POC) accumulation in the Antarctic keystone species, Antarctic krill (Euphausia superba) has been established for a 50 deg. longitudinal range of the eastern Antarctic sector. Samples of adult krill, caught from 12 sites distributed between 30 deg. and 80 deg. E (60-70 deg. S), were analysed for > 100 organohalogen compounds including chlorinated pesticides, polychlorinated biphenyls (PCBs), polybrominated organic compounds and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs). Organochlorine pesticides dominated measured krill contaminant burdens with hexachlorobenzene (HCB) as the single most abundant compound quantified. Krill HCB concentrations were comparable to those detected at this trophic level in both the Arctic and temperate northwest Atlantic, lending support for the hypothesis that HCB will approach global equilibrium at a faster rate than other POCs. Para, para'-dichlorodiphenylethene (p,p'-DDE) was detected at notable concentrations. Measurements of DDT and its degradation products provide an important baseline for monitoring the temporal and geographical influence of renewed, DDT usage for malaria-control in affected southern hemisphere countries. In contrast to the Arctic, PCBs did not feature prominently in contaminant burdens of Antarctic krill. The major commercial polybrominated diphenyl ether (PBDE) congeners -99 and -47 were quantified at low background levels with clear concentration spikes observed at around 70 deg. E , in the vicinity of modern, active research stations. The likelihood that local anthropogenic activities are supplementing low PBDE levels, delivered otherwise primarily via long range environmental transport, is discussed. The suspected naturally occurring brominated organic compound, 2,4,6-tribromoanisole (TBA), was a ubiquitous contaminant in all samples whereas the only PCDD/Fs quantifiable were trace levels of octachlorodibenzo-p-dioxin (OCDD) and 1,2,3

  17. Changes in bird communities of Admiralty Bay, King George Island (West Antarctic: insights from monitoring data (1977–1996

    Directory of Open Access Journals (Sweden)

    Sierakowski Kazimierz

    2017-06-01

    Full Text Available The paper summarizes results of twenty years of seabird observations carried out between 1977 and 1996 on the western shore of Admiralty Bay (King George Island, South Shetlands, Antarctic. Changes in population size, distribution and phenology of the breeding species as well as the appearance of non-breeding species are reported. A total of 34 species of birds were observed, including 13 breeding species. Among the non-breeding species, four were observed to visit the site regularly, six rarely, and the remaining 11 were observed only occasionally. Among breeding populations, three Pygoscelis penguin species, the main krill consumers, were most numerous. The Adélie Penguin (P. adeliae dominated among the penguins nesting in the investigated areas, reaching 23,661 breeding pairs in 1978. Two other penguin species were less abundant with population sizes of approximately 7,200 breeding pairs for the Chinstrap Penguin (P. antarcticus and 3,100 breeding pairs for the Gentoo Penguin (P. papua in the same year. During the following two decades, breeding populations of pygoscelid species experienced a declining trend and their numbers were reduced by 68.0% for Chinstrap, 67.1% for Gentoo, and 33.9% for Adélie Penguins. The data reported here represent a unique reference basis and provide valuable information about indicator species, suitable for comparison with contemporary observations of bird populations in the Antarctic Peninsula region, a place of rapidly occurring climate changes and intensive harvesting of marine living resources.

  18. GENOTOXICITY OF SHALLOW WATERS NEAR THE BRAZILIAN ANTARCTIC STATION "COMANDANTE FERRAZ" (EACF, ADMIRALTY BAY, KING GEORGE ISLAND, ANTARCTICA

    Directory of Open Access Journals (Sweden)

    Arthur José da Silva Rocha

    2015-03-01

    Full Text Available Series of biomonitoring surveys were undertaken weekly in February 2012 to investigate the genotoxicity of the shallow waters around the Brazilian Antarctic Station "Comandante Ferraz" (EACF. The comet assay was applied to assess the damage to the DNA of hemocytes of the crustacean amphipods Gondogeneia antarctica collected from shallow waters near the Fuel Tanks (FT and Sewage Treatment Outflow (STO of the research station, and compare it to the DNA damage of animals from Punta Plaza (PPL and Yellow Point (YP, natural sites far from the EACF defined as experimental controls. The damage to the DNA of hemocytes of G. antarctica was not significantly different between sites in the biomonitoring surveys I and II. In survey III, the damage to the DNA of animals captured in shallow waters near the Fuel Tanks (FT and Sewage Treatment Outflow (STO was significantly higher than that of the control site of Punta Plaza (PPL. In biomonitoring survey IV, a significant difference was detected only between the FT and PPL sites. Results demonstrated that the shallow waters in front of the station may be genotoxic and that the comet assay and hemocytes of G. antarctica are useful tools for assessing genotoxicity in biomonitoring studies of Antarctic marine coastal habitats.

  19. Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

    NARCIS (Netherlands)

    Rugenstein, Maria; Stocchi, Paolo; von der Heydt, Anna; Dijkstra, Hendrik; Brinkhuis, Henk

    2014-01-01

    During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~34 Myr) by combining solid Earth and ocean dynamic

  20. Antarctic and Southern Ocean influences on Late Pliocene global cooling

    NARCIS (Netherlands)

    McKay, R.; Naish, T.; Carter, L.; Riesselman, C.; Dunbar, R.; Sjunneskog, C.; Winter, D.; Sangiorgi, F.; Warren, C.; Pagani, M.; Schouten, S.; Willmott, V.; Levy, R.; DeConto , R.M.; Powell, R.D.

    2012-01-01

    The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL

  1. Microbial ecology and biogeochemistry of continental Antarctic soils

    Directory of Open Access Journals (Sweden)

    Don A Cowan

    2014-04-01

    Full Text Available The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbour microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths possess a genetic capacity for nitrogen and carbon cycling, polymer degradation and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.

  2. South African Antarctic research programme 1978-1982

    CSIR Research Space (South Africa)

    SASCAR

    1978-12-01

    Full Text Available This document provides a comprehensive review of the planned South African scientific activities in Antarctica and on the sub-Antarctic islands in the five year period starting in 1978. The scientific programmes are classified under five headings...

  3. 76 FR 60933 - Antarctic Conservation Act Permit Applications

    Science.gov (United States)

    2011-09-30

    ... NATIONAL SCIENCE FOUNDATION Antarctic Conservation Act Permit Applications AGENCY: National... Conservation Act of 1978. DATES: Interested parties are invited to submit written data, comments, or views with... Regulation for conduct of a flight from South America, over the South Pole, landing at Teniente Marsh Base...

  4. Microbial ecology and biogeochemistry of continental Antarctic soils.

    Science.gov (United States)

    Cowan, Don A; Makhalanyane, Thulani P; Dennis, Paul G; Hopkins, David W

    2014-01-01

    The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbor microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths) possess a genetic capacity for nitrogen and carbon cycling, polymer degradation, and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.

  5. Estimates of numbers of kelp gulls and Kerguelen and Antarctic ...

    African Journals Online (AJOL)

    Four species are regular breeders at the islands: Subantarctic skua Catharacta antarctica, kelp gull Larus dominicanus, Antarctic tern Sterna vittata and Kerguelen tern S. virgata. The latter three species currently each have populations of below 150 breeding pairs at the islands. Kelp gull numbers appear to be relatively ...

  6. Petrology of Antarctic Eucrites PCA 91078 and PCA 91245

    Science.gov (United States)

    Howard, L. M.; Domanik, K. J.; Drake, M. J.; Mittlefehldt, D. W.

    2002-01-01

    Antarctic eucrites PCA 91078 and PCA 91245, are petrographically characterized and found to be unpaired, type 6, basaltic eucrites. Observed textures that provide insight into the petrogenesis of these meteorites are also discussed. Additional information is contained in the original extended abstract.

  7. Evaluating Wind Power Potential in the Spanish Antarctic Base (BAE)

    International Nuclear Information System (INIS)

    Arribas, L.M.; Garcia Barquero, C; Navarro, J.; Cuerva, A.; Cruz, I.; Roque, V.; Marti, I.

    2000-01-01

    The objective of the work is to model wind field in the surroundings of the Spanish Antarctic Base (BAE in the following). The need of such a work comes from the necessity of an energy source able to supply the energy demand in the BAE during the Antarctic winter. When the BAE is in operation (in the Antarctic summer) the energy supply comes from a diesel engine. In the Antarctic winter the base is closed, but the demand of energy supply is growing up every year because of the increase in the number of technical and scientific machines that remain in the BAE taking different measurements. For this purpose the top of a closed hill called Pico Radio, not perturbed by close obstacles, has been chosen as the better site for the measurements. The measurement station is made up with a sonic anemometer and a small wind generator to supply the energy needed by the sensors head heating of the anemometer. This way, it will be also used as a proof for the suitability of a wind generator in the new chosen site, under those special climatic conditions.(Author) 3 refs

  8. Freshwater invertebrates of sub-Antarctic Marion Island | Dartnall ...

    African Journals Online (AJOL)

    The aquatic species include five platyhelminthes, a gastrotrich, three tardigrades, 28 rotifers, six nematodes, two annelids and 11 arthropods. Most are familiar species that have been recorded on other sub-Antarctic islands. The invertebrate faunas of the various freshwater habitats were basically similar in species ...

  9. Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

    NARCIS (Netherlands)

    Rugenstein, M.; Stocchi, P.; van der Heydt, A.; Brinkhuis, H.

    2014-01-01

    During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~ 34 Myr) by combining solid Earth and ocean

  10. Insignificant change in Antarctic snowmelt volume since 1979

    NARCIS (Netherlands)

    Kuipers Munneke, P.; Picard, G.; van den Broeke, M.R.; Lenaerts, J.T.M.; van Meijgaard, E.

    2012-01-01

    Surface snowmelt is widespread in coastal Antarctica. Satellite-based microwave sensors have been observing melt area and duration for over three decades. However, these observations do not reveal the total volume of meltwater produced on the ice sheet. Here we present an Antarctic melt volume

  11. Calving fluxes and basal melt rates of Antarctic ice shelves

    NARCIS (Netherlands)

    Depoorter, M.A.; Bamber, J.L.; Griggs, J.A.; Lenaerts, J.T.M.; Ligtenberg, S.R.M.; van den Broeke, M.R.; Moholdt, G.

    2013-01-01

    Iceberg calving has been assumed to be the dominant cause of mass loss for the Antarctic ice sheet, with previous estimates of the calving flux exceeding 2,000 gigatonnes per year1, 2. More recently, the importance of melting by the ocean has been demonstrated close to the grounding line and near

  12. Dynamic thinning of glaciers on the Southern Antarctic Peninsula

    NARCIS (Netherlands)

    Wouters, B.; Martin-Espanol, A.; Helm, V.; Flament, T.; van Wessem, J. M.; Ligtenberg, S. R. M.; van den Broeke, M. R.; Bamber, J. L.

    2015-01-01

    Growing evidence has demonstrated the importance of ice shelf buttressing on the inland grounded ice, especially if it is resting on bedrock below sea level. Much of the Southern Antarctic Peninsula satisfies this condition and also possesses a bed slope that deepens inland. Such ice sheet geometry

  13. Mucilaginibacter terrae sp nov., isolated from Antarctic soil

    Czech Academy of Sciences Publication Activity Database

    Sedláček, I.; Pantůček, R.; Králová, S.; Mašlaňová, I.; Holochová, P.; Staňková, E.; Sobotka, Roman; Barták, M.; Busse, H.-J.; Švec, P.

    2017-01-01

    Roč. 67, č. 10 (2017), s. 4002-4007 ISSN 1466-5026 R&D Projects: GA MŠk(CZ) LO1416 Institutional support: RVO:61388971 Keywords : Mucilaginibacter terrae sp nov. * James ross island * Antarctic Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.134, year: 2016

  14. A multivariate analysis of Antarctic sea ice since 1979

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes Neto, Newton de; Evangelista, Heitor [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Tanizaki-Fonseca, Kenny [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Universidade Federal Fluminense (UFF), Dept. Analise Geoambiental, Inst. de Geociencias, Niteroi, RJ (Brazil); Penello Meirelles, Margareth Simoes [Universidade do Estado do Rio de Janeiro (UERJ)/Geomatica, Maracana, Rio de Janeiro, RJ (Brazil); Garcia, Carlos Eiras [Universidade Federal do Rio Grande (FURG), Laboratorio de Oceanografia Fisica, Rio Grande, RS (Brazil)

    2012-03-15

    Recent satellite observations have shown an increase in the total extent of Antarctic sea ice, during periods when the atmosphere and oceans tend to be warmer surrounding a significant part of the continent. Despite an increase in total sea ice, regional analyses depict negative trends in the Bellingshausen-Amundsen Sea and positive trends in the Ross Sea. Although several climate parameters are believed to drive the formation of Antarctic sea ice and the local atmosphere, a descriptive mechanism that could trigger such differences in trends are still unknown. In this study we employed a multivariate analysis in order to identify the response of the Antarctic sea ice with respect to commonly utilized climate forcings/parameters, as follows: (1) The global air surface temperature, (2) The global sea surface temperature, (3) The atmospheric CO{sub 2} concentration, (4) The South Annular Mode, (5) The Nino 3, (6) The Nino (3 + 4, 7) The Nino 4, (8) The Southern Oscillation Index, (9) The Multivariate ENSO Index, (10) the Total Solar Irradiance, (11) The maximum O{sub 3} depletion area, and (12) The minimum O{sub 3} concentration over Antarctica. Our results indicate that western Antarctic sea ice is simultaneously impacted by several parameters; and that the minimum, mean, and maximum sea ice extent may respond to a separate set of climatic/geochemical parameters. (orig.)

  15. Modeling the Thermal Interactions of Meteorites Below the Antarctic Ice

    Science.gov (United States)

    Oldroyd, William Jared; Radebaugh, Jani; Stephens, Denise C.; Lorenz, Ralph; Harvey, Ralph; Karner, James

    2017-10-01

    Meteorites with high specific gravities, such as irons, appear to be underrepresented in Antarctic collections over the last 40 years. This underrepresentation is in comparison with observed meteorite falls, which are believed to represent the actual population of meteorites striking Earth. Meteorites on the Antarctic ice sheet absorb solar flux, possibly leading to downward tunneling into the ice, though observations of this in action are very limited. This descent is counteracted by ice sheet flow supporting the meteorites coupled with ablation near mountain margins, which helps to force meteorites towards the surface. Meteorites that both absorb adequate thermal energy and are sufficiently dense may instead reach a shallow equilibrium depth as downward melting overcomes upward forces during the Antarctic summer. Using a pyronometer, we have measured the incoming solar flux at multiple depths in two deep field sites in Antarctica, the Miller Range and Elephant Moraine. We compare these data with laboratory analogues and model the thermal and physical interactions between a variety of meteorites and their surroundings. Our Matlab code model will account for a wide range of parameters used to characterize meteorites in an Antarctic environment. We will present the results of our model along with depth estimates for several types of meteorites. The recovery of an additional population of heavy meteorites would increase our knowledge of the formation and composition of the solar system.

  16. EBSD in Antarctic and Greenland Ice

    Science.gov (United States)

    Weikusat, Ilka; Kuiper, Ernst-Jan; Pennock, Gill; Sepp, Kipfstuhl; Drury, Martyn

    2017-04-01

    boundaries. However, an almost equal number of tilt subgrain boundaries were measured, involving dislocations gliding on non-basal planes (prism or prism slip). A few subgrain boundaries involving prism edge dislocation glide, as well as boundaries involving basal twist dislocation slip, were also identified. The finding that subgrain boundaries built up by dislocations gliding on non-basal planes are as frequent as those originating from basal plane slip is surprising and has impact on the discussion on rate-controlling processes for the ice flow descriptions of large ice masses with respect to sea-level evolution. Weikusat, I.; Miyamoto, A.; Faria, S. H.; Kipfstuhl, S.; Azuma, N. & Hondoh, T.: Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction J. Glaciol., 2011, 57, 85-94

  17. On the origin and evolution of Antarctic Peracarida (Crustacea, Malacostraca

    Directory of Open Access Journals (Sweden)

    Angelika Brandt

    1999-12-01

    Full Text Available The early separation of Gondwana and the subsequent isolation of Antarctica caused a long evolutionary history of its fauna. Both, long environmental stability over millions of years and habitat heterogeneity, due to an abundance of sessile suspension feeders on the continental shelf, favoured evolutionary processes of preadapted taxa, like for example the Peracarida. This taxon performs brood protection and this might be one of the most important reasons why it is very successful (i.e. abundant and diverse in most terrestrial and aquatic environments, with some species even occupying deserts. The extinction of many decapod crustaceans in the Cenozoic might have allowed the Peracarida to find and use free ecological niches. Therefore the palaeogeographic, palaeoclimatologic, and palaeo-hydrographic changes since the Palaeocene (at least since about 60 Ma ago and the evolutionary success of some peracarid taxa (e.g. Amphipoda, Isopoda led to the evolution of many endemic species in the Antarctic. Based on a phylogenetic analysis of the Antarctic Tanaidacea, Sieg (1988 demonstrated that the tanaid fauna of the Antarctic is mainly represented by phylogenetically younger taxa, and data from other crustacean taxa led Sieg (1988 to conclude that the recent Antarctic crustacean fauna must be comparatively young. His arguments are scrutinized on the basis of more recent data on the phylogeny and biodiversity of crustacean taxa, namely the Ostracoda, Decapoda, Mysidacea, Cumacea, Amphipoda, and Isopoda. This analysis demonstrates that the origin of the Antarctic fauna probably has different roots: an adaptive radiation of descendants from old Gondwanian ancestors was hypothesized for the isopod families Serolidae and Arcturidae, an evolution and radiation of phylogenetically old taxa in Antarctica could also be shown for the Ostracoda and the amphipod family Iphimediidae. A recolonization via the Scotia Arc appears possible for some species, though it is

  18. Is there a distinct continental slope fauna in the Antarctic?

    Science.gov (United States)

    Kaiser, Stefanie; Griffiths, Huw J.; Barnes, David K. A.; Brandão, Simone N.; Brandt, Angelika; O'Brien, Philip E.

    2011-02-01

    The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ˜3000 m, is very steep, overlain by 'warm' (2-2.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCAR-MarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelf-slope-abyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a homogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be

  19. Australian and Canadian perspectives and regulations for protecting the polar marine environment

    Energy Technology Data Exchange (ETDEWEB)

    Rothwell, Donald R.

    1997-12-31

    The report compares Australian and Canadian responses for protecting polar marine environments. Vast areas of the polar seas fall within their potential combined EEZ/continental shelf jurisdiction. The Antarctic Treaty provisions, doubts on the status of the Northwest Passage waters and the capacity to enforce legislative initiatives against foreign vessels have been constraints. Australia`s enactment of legislation prohibiting mining within the AAT continental shelf and whaling within the AAT EEZ has tested the Antarctic Treaty. Canada`s reaction to the Manhattan and the enactment of the Arctic Waters Pollution Prevention Act is an example of unilateral action. While the countries have made noteworthy initiatives to enhance the protection of their polar marine environments, doubts remain in some instances on their capacity to give effect to the initiatives. However, sovereignty remains at the heart of their response. Failure to address Antarctic marine environmental issues will rebound on the environment and reflect poorly upon Australia`s sovereignty claim to the AAT. For Canada it is a sovereignty issue and has directly impact upon its citizens inhabiting the islands and coastal areas of the Canadian Arctic. The Madrid Protocol provides the strongest legal basis for the Antarctic Treaty parties to enact laws and regulations in Antarctica. Conservation measures adopted under the Convention for the Conservation of Antarctic Marine Living Resources focuses increasingly on environmental concerns. The most significant regional initiative adopted by Arctic states is the AEPS which does not have a legal foundation. It`s co-operative programs provide basis for co-operation in dealing with environmental problems. It clearly recognises that only co-operative responses will achieve significant outcomes. The 1990s have posed new challenges for marine environmental protection such as ship-based tourism in Antarctica and the growing pressure to use the Northwest Passage on a

  20. Regional Antarctic snow accumulation over the past 1000 years

    Directory of Open Access Journals (Sweden)

    E. R. Thomas

    2017-11-01

    Full Text Available Here we present Antarctic snow accumulation variability at the regional scale over the past 1000 years. A total of 79 ice core snow accumulation records were gathered and assigned to seven geographical regions, separating the high-accumulation coastal zones below 2000 m of elevation from the dry central Antarctic Plateau. The regional composites of annual snow accumulation were evaluated against modelled surface mass balance (SMB from RACMO2.3p2 and precipitation from ERA-Interim reanalysis. With the exception of the Weddell Sea coast, the low-elevation composites capture the regional precipitation and SMB variability as defined by the models. The central Antarctic sites lack coherency and either do not represent regional precipitation or indicate the model inability to capture relevant precipitation processes in the cold, dry central plateau. Our results show that SMB for the total Antarctic Ice Sheet (including ice shelves has increased at a rate of 7 ± 0.13 Gt decade−1 since 1800 AD, representing a net reduction in sea level of ∼ 0.02 mm decade−1 since 1800 and ∼ 0.04 mm decade−1 since 1900 AD. The largest contribution is from the Antarctic Peninsula (∼ 75 % where the annual average SMB during the most recent decade (2001–2010 is 123 ± 44 Gt yr−1 higher than the annual average during the first decade of the 19th century. Only four ice core records cover the full 1000 years, and they suggest a decrease in snow accumulation during this period. However, our study emphasizes the importance of low-elevation coastal zones, which have been under-represented in previous investigations of temporal snow accumulation.

  1. Early cenozoic differentiation of polar marine faunas.

    Directory of Open Access Journals (Sweden)

    J Alistair Crame

    Full Text Available The widespread assumption that the origin of polar marine faunas is linked to the onset of major global cooling in the Late Eocene-Early Oligocene is being increasingly challenged. The Antarctic fossil record in particular is suggesting that some modern Southern Ocean taxa may have Early Eocene or even Paleocene origins, i.e. well within the Early Cenozoic greenhouse world. A global analysis of one of the largest marine clades at the present day, the Neogastropoda, indicates that not only is there a decrease in the number of species from the tropics to the poles but also a decrease in the evenness of their distribution. A small number of neogastropod families with predominantly generalist trophic strategies at both poles points to the key role of seasonality in structuring the highest latitude marine assemblages. A distinct latitudinal gradient in seasonality is temperature-invariant and would have operated through periods of global warmth such as the Early Cenozoic. To test this concept a second global analysis was undertaken of earliest Cenozoic (Paleocene neogastropods and this does indeed show a certain degree of faunal differentiation at both poles. The Buccinidae, s.l. is especially well developed at this time, and this is a major generalist taxon at the present day. There is an element of asymmetry associated with this development of Paleocene polar faunas in that those in the south are more strongly differentiated than their northern counterparts; this can in turn be linked to the already substantial isolation of the southern high latitudes. The key role of seasonality in the formation of polar marine faunas has implications for contemporary ecosystem structure and stability.

  2. Trace-element analysis of Antarctic H chondrites: Chemical weathering and comparisons with their non-Antarctic counterparts

    International Nuclear Information System (INIS)

    Kwok, J.E.

    1986-01-01

    Large numbers of meteorites have been discovered in Antarctica over the last decade (7000 fragments probably representing over 1200 separate events). They are important for their numbers and for their complement of unique or rare specimens; they also have long terrestrial ages (up to 1,000,000 years) compared to non-Antarctic falls (usually < 200 years). We report compositional data for mobile/volatile trace elements Ag, Au, Bi, Cd, Co, Cs, In, Rb, Sb, Se, Te, Ti, U, and Zn in a suite of Antarctic H chondrites. Our data show that heavily oxidized H chondrites are leached of a portion of their trace elements and, therefore, have been chemically compromised by their stay in Antarctica. The less oxidized specimens seem to have retained their chemical integrity. We suggest possibilities for using chemical data to measure the degree of a chondrite's chemical weathering. We compare our data to that obtained previously for non-Antarctic H chondrites (Linger et al., 1986), by petrologic type (H4, H5, H6, H4-6) and shock-loading (moderately shocked facies a-c, heavily shocked facies d-f). Many statistically significant differences are found between non-Antarctic and Victoria Land, Antarctica H chondrites of each petrologic type and of shock facies d-f

  3. Silicon Isotopes of Marine Pore Water: Tracking the Destiny of Marine Biogenic Opal

    Science.gov (United States)

    Cassarino, L.; Hendry, K. R.

    2017-12-01

    Silicon isotopes (δ30Si) are a powerful tool for the studying of the past and present silicon cycles, which is closely linked to the carbon cycle. Siliceous phytoplankton, such as diatoms, as one of the major conveyors of carbon to marine sediments. δ30Si from fossil diatoms has been shown to represent past silicic acid (DSi) utilization in the photic zone, since the lighter isotope is preferentially incorporated in their skeleton, the frustule. This assumes that species in the sediments depict past blooms and that frustules are preserved in their initial state during burial. Here we present new silicon isotopes data of sea water and pore water of deep marine sediments from two contrasted environments, the Equatorial Atlantic and West Antarctic Peninsula. δ30Si and DSi concentration, of both sea water and pore water, are negatively correlated. Marine biogenic opal dissolution can be tracked using δ30Si signature of pore water as lighter signals and high DSi concentrations are associated with the biogenic silica. Our data enhances post depositional and diagenesis processes during burial with a clear highlight on the sediment water interface exchanges.

  4. beta-diversity and species accumulation in antarctic coastal benthos: influence of habitat, distance and productivity on ecological connectivity.

    Directory of Open Access Journals (Sweden)

    Simon F Thrush

    Full Text Available High Antarctic coastal marine environments are comparatively pristine with strong environmental gradients, which make them important places to investigate biodiversity relationships. Defining how different environmental features contribute to shifts in beta-diversity is especially important as these shifts reflect both spatio-temporal variations in species richness and the degree of ecological separation between local and regional species pools. We used complementary techniques (species accumulation models, multivariate variance partitioning and generalized linear models to assess how the roles of productivity, bio-physical habitat heterogeneity and connectivity change with spatial scales from metres to 100's of km. Our results demonstrated that the relative importance of specific processes influencing species accumulation and beta-diversity changed with increasing spatial scale, and that patterns were never driven by only one factor. Bio-physical habitat heterogeneity had a strong influence on beta-diversity at scales 40 km. Our analysis supports the emphasis on the analysis of diversity relationships across multiple spatial scales and highlights the unequal connectivity of individual sites to the regional species pool. This has important implications for resilience to habitat loss and community homogenisation, especially for Antarctic benthic communities where rates of recovery from disturbance are slow, there is a high ratio of poor-dispersing and brooding species, and high biogenic habitat heterogeneity and spatio-temporal variability in primary production make the system vulnerable to disturbance. Consequently, large areas need to be included within marine protected areas for effective management and conservation of these special ecosystems in the face of increasing anthropogenic disturbance.

  5. beta-diversity and species accumulation in antarctic coastal benthos: influence of habitat, distance and productivity on ecological connectivity.

    Science.gov (United States)

    Thrush, Simon F; Hewitt, Judi E; Cummings, Vonda J; Norkko, Alf; Chiantore, Mariachiara

    2010-07-30

    High Antarctic coastal marine environments are comparatively pristine with strong environmental gradients, which make them important places to investigate biodiversity relationships. Defining how different environmental features contribute to shifts in beta-diversity is especially important as these shifts reflect both spatio-temporal variations in species richness and the degree of ecological separation between local and regional species pools. We used complementary techniques (species accumulation models, multivariate variance partitioning and generalized linear models) to assess how the roles of productivity, bio-physical habitat heterogeneity and connectivity change with spatial scales from metres to 100's of km. Our results demonstrated that the relative importance of specific processes influencing species accumulation and beta-diversity changed with increasing spatial scale, and that patterns were never driven by only one factor. Bio-physical habitat heterogeneity had a strong influence on beta-diversity at scales 40 km. Our analysis supports the emphasis on the analysis of diversity relationships across multiple spatial scales and highlights the unequal connectivity of individual sites to the regional species pool. This has important implications for resilience to habitat loss and community homogenisation, especially for Antarctic benthic communities where rates of recovery from disturbance are slow, there is a high ratio of poor-dispersing and brooding species, and high biogenic habitat heterogeneity and spatio-temporal variability in primary production make the system vulnerable to disturbance. Consequently, large areas need to be included within marine protected areas for effective management and conservation of these special ecosystems in the face of increasing anthropogenic disturbance.

  6. A circadian clock in Antarctic krill: an endogenous timing system governs metabolic output rhythms in the euphausid species Euphausia superba.

    Directory of Open Access Journals (Sweden)

    Mathias Teschke

    Full Text Available Antarctic krill, Euphausia superba, shapes the structure of the Southern Ocean ecosystem. Its central position in the food web, the ongoing environmental changes due to climatic warming, and increasing commercial interest on this species emphasize the urgency of understanding the adaptability of krill to its environment. Krill has evolved rhythmic physiological and behavioral functions which are synchronized with the daily and seasonal cycles of the complex Southern Ocean ecosystem. The mechanisms, however, leading to these rhythms are essentially unknown. Here, we show that krill possesses an endogenous circadian clock that governs metabolic and physiological output rhythms. We found that expression of the canonical clock gene cry2 was highly rhythmic both in a light-dark cycle and in constant darkness. We detected a remarkable short circadian period, which we interpret as a special feature of the krill's circadian clock that helps to entrain the circadian system to the extreme range of photoperiods krill is exposed to throughout the year. Furthermore, we found that important key metabolic enzymes of krill showed bimodal circadian oscillations (∼9-12 h period in transcript abundance and enzymatic activity. Oxygen consumption of krill showed ∼9-12 h oscillations that correlated with the temporal activity profile of key enzymes of aerobic energy metabolism. Our results demonstrate the first report of an endogenous circadian timing system in Antarctic krill and its likely link to metabolic key processes. Krill's circadian clock may not only be critical for synchronization to the solar day but also for the control of seasonal events. This study provides a powerful basis for the investigation into the mechanisms of temporal synchronization in this marine key species and will also lead to the first comprehensive analyses of the circadian clock of a polar marine organism through the entire photoperiodic cycle.

  7. 14C as a tracer of labile organic matter in Antarctic benthic food webs

    Science.gov (United States)

    Purinton, Brett L.; DeMaster, David J.; Thomas, Carrie J.; Smith, Craig R.

    2008-11-01

    14C measurements were made on surface plankton, particle-trap material, surface sediment, benthic invertebrate gut contents, and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula (WAP) shelf between November 1999 and March 2001 as part of the Food for Benthos on the ANtarctic Continental-Shelf (FOODBANCS) Project. The 14C contents of the body tissues from a variety of deposit feeders (-126±13 per mil) were substantially enriched relative to the surface sediment (-234±13 per mil) and statistically similar to the organic matter collected in plankton tows (-135±10 per mil), indicating that recently produced marine plankton are the primary source of nutrition for these deposit feeders on the West Antarctic shelf. Selective ingestion was the primary feeding strategy used by echiuran worms and certain holothurians (i.e. Peniagone vignoni) for incorporating labile organic carbon into their tissues as demonstrated by the large differences (105±13 per mil) between surface sediment and gut content 14C activities. In contrast, digestive and/or assimilatory selection was the predominant strategy used by an irregular urchin ( Amphipneustes lorioli) and several other holothurians ( Protelpidia murrayi, Bathyplotes fuscivinculum and the head-down conveyor belt feeder, Molpadia musculus), as demonstrated by large differences (42±7 per mil) between the 14C activities of their foregut or whole-gut organic contents and their body tissues. Despite large fluctuations in carbon export from the euphotic zone, benthic feeding strategies remained essentially constant over the 15-month sampling period. No seasonal variation was evident in either the 14C abundance of the deposit-feeder body tissues, or in the 14C abundance of their gut contents. The mean 14C abundance in the body tissues of the two sub-surface deposit feeders ( A

  8. Polar Frontal Migration in the Warm Late Pliocene: Diatom Evidence from The Wilkes Land Margin, East Antarctic

    Science.gov (United States)

    Riesselman, C. R.; Taylor-Silva, B.; Patterson, M. O.

    2017-12-01

    The Late Pliocene is the most recent interval in Earth's history to sustain global temperatures within the range of warming predicted for the 21st century. Published global reconstructions and climate models find an average +2° C summer SST anomaly relative to modern during the 3.3-3.0 Ma PRISM interval, when atmospheric CO2 concentrations last reached 400 ppm. Here, we present a new diatom-based reconstruction of Pliocene interglacial sea surface conditions from IODP Site U1361, on the East Antarctic continental rise. U1361 biogenic silica concentrations document the alternation of diatom-rich and diatom-poor lithologies; we interpret 8 diatom-rich mudstones within this sequence to record interglacial periods between 3.8 and 2.8 Ma. We find that open-ocean conditions in the mid-Pliocene became increasingly influenced by sea ice from 3.6-3.2 Ma, prior to the onset of Northern Hemisphere glaciation. This cooling trend was interrupted by a temporary southward migration of the Antarctic Polar Front, bathing U1361 in warmer subantarctic waters during a single interglacial, marine isotope stage KM3 (3.17-3.15 Ma), that corresponds to a maximum in summer insolation at 65°S. Following this interval of transient warmth, interglacial periods became progressively cooler starting at 3 Ma, coinciding with a transition from obliquity to precession as the dominant orbital driver of Antarctic ice sheet fluctuations. Building on the identification of a single outlier interglacial within the PRISM interval, we have revisited older reconstructions to explore the response of the Southern Ocean/cryosphere system to peak late Pliocene warmth. By applying a modern chronostratigraphic framework to those low-resolution "mean interglacial" records, we identify the same frontal migration in 4 other cores in the Pacific sector of the Southern Ocean, documenting a major migration of the polar front during a key interval of warm climate. These new results suggest that increased summer

  9. Heavy metal distribution in organic and siliceous marine sponge tissues measured by square wave anodic stripping voltammetry.

    Science.gov (United States)

    Illuminati, S; Annibaldi, A; Truzzi, C; Scarponi, G

    2016-10-15

    May sponge spicules represent a "tank" to accumulate heavy metals? In this study we test this hypothesis determining the distribution of Cd, Pb and Cu concentrations between organic and siliceous tissues in Antarctic Demospongia (Sphaerotylus antarcticus, Kirkpatrikia coulmani and Haliclona sp.) and in the Mediterranean species Petrosia ficiformis. Results show that although, in these sponges, spicules represent about 80% of the mass content, the accumulation of pollutant is lower in the spicules than in the corresponding organic fraction. The contribution of tissues to the total sponge content of Cd, Pb and Cu is respectively 99%, 82% and 97% for Antarctic sponges and 96%, 95% and 96% for P. ficiformis, similar in polar and temperate organisms. These results pave the way to a better understanding of the role of marine sponges in uptaking heavy metals and to their possible use as monitor of marine ecosystems, recommend by the Water Framework Directive. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Arctic and Antarctic Sea Ice Changes and Impacts (Invited)

    Science.gov (United States)

    Nghiem, S. V.

    2013-12-01

    The extent of springtime Arctic perennial sea ice, important to preconditioning summer melt and to polar sunrise photochemistry, continues its precipitous reduction in the last decade marked by a record low in 2012, as the Bromine, Ozone, and Mercury Experiment (BROMEX) was conducted around Barrow, Alaska, to investigate impacts of sea ice reduction on photochemical processes, transport, and distribution in the polar environment. In spring 2013, there was further loss of perennial sea ice, as it was not observed in the ocean region adjacent to the Alaskan north coast, where there was a stretch of perennial sea ice in 2012 in the Beaufort Sea and Chukchi Sea. In contrast to the rapid and extensive loss of sea ice in the Arctic, Antarctic sea ice has a trend of a slight increase in the past three decades. Given the significant variability in time and in space together with uncertainties in satellite observations, the increasing trend of Antarctic sea ice may arguably be considered as having a low confidence level; however, there was no overall reduction of Antarctic sea ice extent anywhere close to the decreasing rate of Arctic sea ice. There exist publications presenting various factors driving changes in Arctic and Antarctic sea ice. After a short review of these published factors, new observations and atmospheric, oceanic, hydrological, and geological mechanisms contributed to different behaviors of sea ice changes in the Arctic and Antarctic are presented. The contribution from of hydrologic factors may provide a linkage to and enhance thermal impacts from lower latitudes. While geological factors may affect the sensitivity of sea ice response to climate change, these factors can serve as the long-term memory in the system that should be exploited to improve future projections or predictions of sea ice changes. Furthermore, similarities and differences in chemical impacts of Arctic and Antarctic sea ice changes are discussed. Understanding sea ice changes and

  11. The sensitivity of dimethyl sulfide production to simulated climate change in the Eastern Antarctic Southern Ocean

    International Nuclear Information System (INIS)

    Gabric, Albert J.; Cropp, Roger; Marchant, Harvey

    2003-01-01

    Dimethyl sulfide (DMS) is a radiatively active trace gas produced by enzymatic cleavage of its precursor compound, dimethyl sulfoniopropionate (DMSP), which is released by marine phytoplankton in the upper ocean. Once ventilated to the atmosphere, DMS is oxidised to form non-sea-salt sulfate and methane sulfonate (MSA) aerosols, which are a major source of cloud condensation nuclei (CCN) in remote marine air and may thus play a role in climate regulation. Here we simulate the change in DMS flux in the Eastern Antarctic ocean from 1960-2086, corresponding to equivalent CO 2 tripling relative to pre-industrial levels. Calibration to contemporary climate conditions was carried out using a genetic algorithm to fit the model to surface chlorophyll from the 4-yr SeaWiFs satellite archive and surface DMS from an existing global database. Following the methodology used previously in the Subantarctic Southern Ocean, we then simulated DMS emissions under enhanced greenhouse conditions by forcing the DMS model with output from a coupled atmospheric-ocean general circulation model (GCM). The GCM was run in transient mode under the IPCC/IS92a radiative forcing scenario. By 2086, the change simulated in annual integrated DMS flux is around 20% in ice-free waters, with a greater increase of 45% in the seasonal ice zone (SIZ). Interestingly, the large increase in flux in the SIZ is not due to higher in situ production but mainly because of a loss of ice cover during summer-autumn and an increase in sea-to-air ventilation of DMS. These proportional changes in areal mean flux (25%) are much higher than previously estimated for the Subantarctic Southern Ocean (5%), and point to the possibility of a significant DMS-climate feedback at high Southern latitudes. Due to the nexus between ice cover and food-web structure, the potential for ecological community shifts under enhanced greenhouse conditions is high, and the implications for DMS production are discussed

  12. Life cycle environmental impacts of three products derived from wild-caught Antarctic krill (Euphausia superba).

    Science.gov (United States)

    Parker, Robert W R; Tyedmers, Peter H

    2012-05-01

    Concern has been voiced in recent years regarding the environmental implications of the Antarctic krill fishery. Attention has focused primarily on ecological concerns, whereas other environmental aspects, including potentially globally problematic emissions and material and energy demands, have not been examined in detail. Here we apply life cycle assessment to measure the contributions of krill meal, oil, and omega-3 capsules to global warming, ozone depletion, acidification, eutrophication, energy use, and biotic resource use. Supply chains of one krill fishing and processing company, Aker BioMarine of Norway, were assessed. Impacts of krill products were found to be driven primarily by the combustion of fossil fuels onboard the fishing vessel and a transport/resupply vessel. Approximately 190 L of fuel are burned per tonne of raw krill landed, markedly higher than fuel inputs to reduction fisheries targeting other species. In contrast, the biotic resource use associated with extracting krill is relatively low compared to that of other reduction fisheries. Results of this study provide insight into the broader environmental implications of the krill fishery, comparisons between products derived from krill and other species targeted for reduction, opportunities for improving the fishery's performance, and a baseline against which to measure future performance. © 2012 American Chemical Society

  13. The paradox of a long grounding during West Antarctic Ice Sheet retreat in Ross Sea.

    Science.gov (United States)

    Bart, Philip J; Krogmeier, Benjamin J; Bart, Manon P; Tulaczyk, Slawek

    2017-04-28

    Marine geological data show that the West Antarctic Ice Sheet (WAIS) advanced to the eastern Ross Sea shelf edge during the Last Glacial Maximum (LGM) and eventually retreated ~1000 km to the current grounding-line position on the inner shelf. During the early deglacial, the WAIS deposited a voluminous stack of overlapping grounding zone wedges (GZWs) on the outer shelf of the Whales Deep Basin. The large sediment volume of the GZW cluster suggests that the grounding-line position of the paleo-Bindschadler Ice Stream was relatively stationary for a significant time interval. We used an upper bound estimate of paleo-sediment flux to investigate the lower bound duration over which the ice stream would have deposited sediment to account for the GZW volume. Our calculations show that the cluster represents more than three millennia of ice-stream sedimentation. This long duration grounding was probably facilitated by rapid GZW growth. The subsequent punctuated large-distance (~200 km) grounding-line retreat may have been a highly non-linear ice sheet response to relatively continuous external forcing such as gradual climate warming or sea-level rise. These findings indicate that reliable predictions of future WAIS retreat may require incorporation of realistic calculations of sediment erosion, transport and deposition.

  14. The effects of oil pollution on Antarctic benthic diatom communities over 5 years

    International Nuclear Information System (INIS)

    Polmear, R.; Stark, J.S.; Roberts, D.; McMinn, A.

    2015-01-01

    Highlights: • We examine the impact of hydrocarbon pollution on Antarctic benthic diatoms. • The effect of standard synthetic lubricant oil and a biodegradable oil were examined. • There were significant effects from both treatments for over 5 years. • There was little difference between the different types of oil. - Abstract: Although considered pristine, Antarctica has not been impervious to hydrocarbon pollution. Antarctica’s history is peppered with oil spills and numerous abandoned waste disposal sites. Both spill events and constant leakages contribute to previous and current sources of pollution into marine sediments. Here we compare the response of the benthic diatom communities over 5 years to exposure to a commonly used standard synthetic lubricant oil, an alternative lubricant marketed as more biodegradable, in comparison to a control treatment. Community composition varied significantly over time and between treatments with some high variability within contaminated treatments suggesting community stress. Both lubricants showed evidence of significant effects on community composition after 5 years even though total petroleum hydrocarbon reduction reached approximately 80% over this time period. It appears that even after 5 years toxicity remains high for both the standard and biodegradable lubricants revealing the temporal scale at which pollutants persist in Antarctica

  15. Antarctic contribution to meltwater pulse 1A from reduced Southern Ocean overturning.

    Science.gov (United States)

    Golledge, N R; Menviel, L; Carter, L; Fogwill, C J; England, M H; Cortese, G; Levy, R H

    2014-09-29

    During the last glacial termination, the upwelling strength of the southern polar limb of the Atlantic Meridional Overturning Circulation varied, changing the ventilation and stratification of the high-latitude Southern Ocean. During the same period, at least two phases of abrupt global sea-level rise--meltwater pulses--took place. Although the timing and magnitude of these events have become better constrained, a causal link between ocean stratification, the meltwater pulses and accelerated ice loss from Antarctica has not been proven. Here we simulate Antarctic ice sheet evolution over the last 25 kyr using a data-constrained ice-sheet model forced by changes in Southern Ocean temperature from an Earth system model. Results reveal several episodes of accelerated ice-sheet recession, the largest being coincident with meltwater pulse 1A. This resulted from reduced Southern Ocean overturning following Heinrich Event 1, when warmer subsurface water thermally eroded grounded marine-based ice and instigated a positive feedback that further accelerated ice-sheet retreat.

  16. Muricauda antarctica sp. nov., a marine member of the Flavobacteriaceae isolated from Antarctic seawater.

    Science.gov (United States)

    Wu, Yue-Hong; Yu, Pei-Song; Zhou, Ya-Dong; Xu, Lin; Wang, Chun-Sheng; Wu, Min; Oren, Aharon; Xu, Xue-Wei

    2013-09-01

    A Gram-stain-negative, rod-shaped bacterium with appendages, designated Ar-22(T), was isolated from a seawater sample collected from the western part of Prydz Bay, near Cape Darnley, Antarctica. Strain Ar-22(T) grew optimally at 35 °C, at pH 7.5 and in the presence of 1-3% (w/v) NaCl. The isolate was positive for casein, gelatin and Tween 20 decomposition and negative for H2S production and indole formation. Chemotaxonomic analysis showed that MK-6 was the major isoprenoid quinone and phosphatidylethanolamine was the major polar lipid. The major fatty acids were iso-C(17:0) 3-OH, iso-C(15:1) G, iso-C(15:0) and C(16:1)ω7c/iso-C(15:0) 2OH. The genomic DNA G+C content was 44.8 mol%. Comparative 16S rRNA gene sequence analysis revealed that strain Ar-22(T) is closely related to members of the genus Muricauda, sharing 94.2-97.3% sequence similarity with the type strains of species of the genus Muricauda and being most closely related to the Muricauda aquimarina. Phylogenetic analysis based on the 16S rRNA gene sequence comparison confirmed that strain Ar-22(T) formed a deep lineage with Muricauda flavescens. Sequence similarity between strain Ar-22(T) and Muricauda ruestringensis DSM 13258(T), the type species of the genus Muricauda, was 96.9%. Strain Ar-22(T) exhibited mean DNA-DNA relatedness values of 40.1%, 49.4% and 25.7% to M. aquimarina JCM 11811(T), M. flavescens JCM 11812(T) and Muricauda lutimaris KCTC 22173(T), respectively. On the basis of phenotypic and genotypic data, strain Ar-22(T) represents a novel species of the genus Muricauda, for which the name Muricauda antarctica sp. nov. (type strain Ar-22(T) =CGMCC 1.12174(T) = JCM 18450(T)) is proposed.

  17. The trophic role of the tunicate Salpa thompsoni in the Antarctic marine ecosystem

    Science.gov (United States)

    Perissinotto, Renzo; Pakhomov, Evgeny A.

    1998-11-01

    During a repeat grid survey and drogue study carried out in austral summer 1994/95, the abundance and feeding activity of salps were estimated in the Lazarev Sea region from net tows and in situ measurements of gut fluorescence. Throughout the survey area, Salpa thompsoni accounted for >95% of the total salp stock while Ihlea racovitzai was consistently represented in very low abundances. Maximum densities of S. thompsoni, with ≈4000 ind. 1000 m -3, were recorded in the Marginal Ice Zone (MIZ) in December when chlorophyll- a concentrations were well below 1 mg m -3. A dramatic decrease in salp stock was observed at the beginning of January, when S. thompsoni virtually disappeared from the most productive area of the MIZ where chlorophyll- a concentrations had by then reached bloom levels of 1.5-3 mg (Chl-a) m -3. In situ grazing measurements showed that throughout the cruise S. thompsoni exhibited the highest ingestion rates per individual of any of the most abundant components of the grazing pelagic community, with maxima of ≈160 μg (pigm) ind. -1 d -1. These feeding rates are 3 to 5 times higher than those previously obtained using in vitro incubations. The total daily consumption of the population of S. thompsoni varied from 0.3 to 108% of daily primary production. We suggest that competitive removal of food by S. thompsoni, rather than direct predation, is responsible for the low krill abundances generally associated with salp swarms.

  18. Marine studies at the western Antarctic Peninsula: Priorities, progress and prognosis

    Science.gov (United States)

    Meredith, Michael P.; Stefels, Jacqueline; van Leeuwe, Maria

    2017-05-01

    Since its discovery and the early heroic age of its exploration, Antarctica has held a fascination for scientists and the general public alike. Being an untouched wilderness, images of Antarctica inspired researchers to survey it for new discoveries that had the potential to radically reshape understanding of our planet and the life that it inhabits. Many of the early expeditions that charted Antarctica carried scientific parties, eager to increase the sum of human knowledge in addition to testing human endurance in the harshest of environments.

  19. A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond

    OpenAIRE

    Kennicutt, M.C.; Chown, S.L.; Cassano, J.J.; Liggett, D.; Peck, L.S.; Massom, R.; Rintoul, S.R.; Storey, J.; Vaughan, D.G.; Wilson, T.J.; Allison, I.; Ayton, J.; Badhe, R.; Baeseman, J.; Barrett, P.J.

    2015-01-01

    Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the horizon’ to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consu...

  20. Stable isotopes and Antarctic moss banks: Plants and soil microbes respond to recent warming on the Antarctic Peninsula

    Science.gov (United States)

    Royles, Jessica; Amesbury, Matthew; Ogée, Jérôme; Wingate, Lisa; Convey, Peter; Hodgson, Dominic; Griffiths, Howard; Leng, Melanie; Charman, Dan

    2014-05-01

    The Antarctic Peninsula is one of the most rapidly warming regions on Earth, with air temperature increases of as much as 3°C recorded since the 1950s. However, the longer-term context of this change is limited and existing records, largely relying on ice core data, are not suitably located to be able to trace the spatial signature of change over time. We are working on a project exploiting stable isotope records preserved in moss peat banks spanning 10 degrees of latitude along the Antarctic Peninsula as an archive of late Holocene climate variability. Here we present a unique time series of past moss growth and soil microbial activity that has been produced from a 150 year old moss bank at Lazarev Bay, Alexander Island (69°S), a site at the southern limit of significant plant growth in the Antarctic Peninsula region. These moss banks are ideal archives for palaeoclimate research as they are well-preserved by freezing, generally monospecific, easily dated by radiocarbon techniques, and have sufficiently high accumulation rates to permit decadal resolution. We use accumulation rates, cellulose δ13C and fossil testate amoebae to show that growth rates, assimilation and microbial productivity rose rapidly in the 1960s, consistent with temperature change, although recently may have stalled, concurrent with other evidence. The increase in biological activity is unprecedented in the last 150 years. Along with work completed on Signy Island (60°S), in the South Orkney Islands, in which we used carbon isotope evidence to show recent climate-related enhancement of CO2 assimilation and peat accumulation rates in Antarctica, the observed relationships between moss growth, microbial activity and climate suggests that moss bank records have the potential to test the regional expression of temperature variability shown by instrumental data on the Antarctic Peninsula over centennial to millennial timescales, by providing long-term records of summer growth conditions

  1. Turning microplastics into nanoplastics through digestive fragmentation by Antarctic krill.

    Science.gov (United States)

    Dawson, Amanda L; Kawaguchi, So; King, Catherine K; Townsend, Kathy A; King, Robert; Huston, Wilhelmina M; Bengtson Nash, Susan M

    2018-03-08

    Microplastics (plastics microplastics through ingestion. Here, by exposing Antarctic krill (Euphausia superba) to microplastics under acute static renewal conditions, we present evidence of physical size alteration of microplastics ingested by a planktonic crustacean. Ingested microplastics (31.5 µm) are fragmented into pieces less than 1 µm in diameter. Previous feeding studies have shown spherical microplastics either; pass unaffected through an organism and are excreted, or are sufficiently small for translocation to occur. We identify a new pathway; microplastics are fragmented into sizes small enough to cross physical barriers, or are egested as a mixture of triturated particles. These findings suggest that current laboratory-based feeding studies may be oversimplifying interactions between zooplankton and microplastics but also introduces a new role of Antarctic krill, and potentially other species, in the biogeochemical cycling and fate of plastic.

  2. Are Antarctic ozone variations a manifestation of dynamics or chemistry?

    Science.gov (United States)

    Tung, K.-K.; Ko, M. K. W.; Rodriguez, J. M.; Sze, N. D.

    1986-01-01

    The existence of a reverse circulation cell with rising motion in the polar lower stratosphere is suggested as an explanation for the temporal behavior of the ozone column density in the Antarctic region. The upwelling brings ozone-poor air from below 100 mbar to the stratosphere, possibly contributing to the observed ozone decline in early spring. At the same time, the Antarctic stratosphere might contain a very low concentration of NO(x), a condition that could favor a greatly enhanced catalytic removal of O3 by halogen species. It is argued that heterogeneous processes and formation of OClO by the reaction BrO+ClO - OClO+Br before and after the polar night might help to suppress the NO(x) levels during the early spring period.

  3. Development of the interface software for the Antarctic penetrator

    Directory of Open Access Journals (Sweden)

    Kazuo Shibuya

    2005-11-01

    Full Text Available We have developed PC-based interface software which controls ground system segments (GSSs of the Antarctic penetrator through an automatic data collection system onboard a helicopter. A pen-touch panel was developed for easy operation. There are six basic functions in the interface software; GSS time synchronization", make schedule file", send schedule file", GSS time calibration", data read-out", and sleep". The sleep command enables us to cut off the radio transmitter/receiver to save power during a pre-determined period. After execution of each command, log files are saved automatically. In order to monitor processing by eye, a bar graph appears during execution of time synchronization" and data read-out". As for malfunctioning encountered during the 43rd Japanese Antarctic Research Expedition, the related software bugs were identified and the codes were rewritten.

  4. The delta18O composition of Antarctic coastal current waters

    International Nuclear Information System (INIS)

    Frew, R.; Heywood, K.; Dennis, P.

    1997-01-01

    The varying proportions of 18 O to 16 O in sea water provide an oceanographic trace like salinity, but with an extra degree of freedom: salt is a tracer for the oceanic fluid, whereas the isotopic composition is a tracer specifically for the water component of that fluid. Hydrogen and oxygen isotopes are the variables most intimately related to the water component in the sea, therefore thay furnish a direct link to the water in the atmosphere and on continents and to the precipitation cycle which caused the salinity changes. The ratio of 18 O to 16 O (delta 18 O) ot waters is a powerful tracer in polar regions where sea and glacial ice processes decouple delta 18 O from salinity. Here we present observations from a significant but relatively unexplored component of the Southern Ocean current system, the Antarctic Coastal Current, and its associated Antarctic Slope Front. (author)

  5. Marine animal stings or bites

    Science.gov (United States)

    Stings - marine animals; Bites - marine animals ... Things you can do to prevent a marine animal sting or bite include: Swim near a lifeguard. Observe posted signs that may warn of danger from jellyfish or other hazardous marine life. ...

  6. Molluscan systematics and biostratigraphy: lower tertiary, La Meseta formation, Seymour Island, Antarctic Peninsula

    National Research Council Canada - National Science Library

    Stilwell, Jeffrey D; Zinsmeister, William J

    1992-01-01

    Contents: The Antarctic research series: statement of objectives - Acknowledgements - Abstract - Introduction - Previous investigations - Stratigraphy - Age of the La Meseta Formation - Biostratigraphy - Depositional environments...

  7. Basin-scale heterogeneity in Antarctic precipitation and its impact on surface mass variability

    Directory of Open Access Journals (Sweden)

    J. Fyke

    2017-11-01

    Full Text Available Annually averaged precipitation in the form of snow, the dominant term of the Antarctic Ice Sheet surface mass balance, displays large spatial and temporal variability. Here we present an analysis of spatial patterns of regional Antarctic precipitation variability and their impact on integrated Antarctic surface mass balance variability simulated as part of a preindustrial 1800-year global, fully coupled Community Earth System Model simulation. Correlation and composite analyses based on this output allow for a robust exploration of Antarctic precipitation variability. We identify statistically significant relationships between precipitation patterns across Antarctica that are corroborated by climate reanalyses, regional modeling and ice core records. These patterns are driven by variability in large-scale atmospheric moisture transport, which itself is characterized by decadal- to centennial-scale oscillations around the long-term mean. We suggest that this heterogeneity in Antarctic precipitation variability has a dampening effect on overall Antarctic surface mass balance variability, with implications for regulation of Antarctic-sourced sea level variability, detection of an emergent anthropogenic signal in Antarctic mass trends and identification of Antarctic mass loss accelerations.

  8. Introduction. Antarctic ecology: from genes to ecosystems. Part 2. Evolution, diversity and functional ecology.

    Science.gov (United States)

    Rogers, Alex D; Murphy, Eugene J; Johnston, Nadine M; Clarke, Andrew

    2007-12-29

    The Antarctic biota has evolved over the last 100 million years in increasingly isolated and cold conditions. As a result, Antarctic species, from micro-organisms to vertebrates, have adapted to life at extremely low temperatures, including changes in the genome, physiology and ecological traits such as life history. Coupled with cycles of glaciation that have promoted speciation in the Antarctic, this has led to a unique biota in terms of biogeography, patterns of species distribution and endemism. Specialization in the Antarctic biota has led to trade-offs in many ecologically important functions and Antarctic species may have a limited capacity to adapt to present climate change. These include the direct effects of changes in environmental parameters and indirect effects of increased competition and predation resulting from altered life histories of Antarctic species and the impacts of invasive species. Ultimately, climate change may alter the responses of Antarctic ecosystems to harvesting from humans. The unique adaptations of Antarctic species mean that they provide unique models of molecular evolution in natural populations. The simplicity of Antarctic communities, especially from terrestrial systems, makes them ideal to investigate the ecological implications of climate change, which are difficult to identify in more complex systems.

  9. Measurement of the electrostatic field in aurora by antarctic rocket

    International Nuclear Information System (INIS)

    Takeya, Yoshio; Minami, Shigeyuki

    1974-01-01

    The direct measurement of the electrostatic field produced by the flow of charged particles and geomagnetic field in aurora has been carried out by means of rockets or satellites. The construction of an electric field meter and its characteristics are described, which measures the vectors of electric field with antarctic rockets. New scheme is presented: three components of an electric field are directly obtained through the probes set in three directions. (Mori, K.)

  10. Atmospheric Influences on the Anomalous 2016 Antarctic Sea Ice Decay

    Science.gov (United States)

    Raphael, M. N.; Schlosser, E.; Haumann, A.

    2017-12-01

    Over the past three decades, a small but significant increase in sea ice extent (SIE) has been observed in the Antarctic. However, in 2016 there was a surprisingly early onset of the melt season. The maximum Antarctic SIE was reached in August rather than end of September, and was followed by a rapid decrease. The decline of the sea ice area (SIA) started even earlier, in July. The retreat of the ice was particularly large in November where Antarctic SIE exhibited a negative anomaly (compared to the 1981-2010 average) of almost 2 Mio. km2, which, combined with reduced Arctic SIE, led to a distinct minimum in global SIE. And, satellite observations show that from November 2016 to February 2017, the daily Antarctic SIE has been at record low levels. We use sea level pressure and geopotential height data from the ECMWF- Interim reanalysis, in conjunction with sea ice data obtained from the National Snow and Ice Data Centre (NSIDC), to investigate possible atmospheric influences on the observed phenomena. Indications are that both the onset of the melt in July and the rapid decrease in SIA and SIE in November were triggered by atmospheric flow patterns related to a positive Zonal Wave 3 index, i.e. synoptic situations leading to strong meridional flow. Additionally the Southern Annular Mode (SAM) index reached its second lowest November value since the beginning of the satellite observations. It is likely that the SIE decrease was preconditioned by SIA decrease. Positive feedback effects led to accelerated melt and consequently to the extraordinary low November SIE.

  11. Geochemical signatures of tephras from Quaternary Antarctic Peninsula volcanoes

    OpenAIRE

    Kraus,Stefan; Kurbatov,Andrei; Yates,Martin

    2013-01-01

    In the northern Antarctic Peninsula area, at least 12 Late Plelstocene-Holocene volcanic centers could be potential sources of tephra layers in the region. We present unique geochemical fingerprints for ten of these volcanoes using major, trace, rare earth element, and isotope data from 95 samples of tephra and other eruption products. The volcanoes have predominantly basaltic and basaltic andesitic compositions. The Nb/Y ratio proves useful to distinguish between volcanic centers located on ...

  12. Antarctic sea ice losses drive gains in benthic carbon drawdown.

    Science.gov (United States)

    Barnes, D K A

    2015-09-21

    Climate forcing of sea-ice losses from the Arctic and West Antarctic are blueing the poles. These losses are accelerating, reducing Earth's albedo and increasing heat absorption. Subarctic forest (area expansion and increased growth) and ice-shelf losses (resulting in new phytoplankton blooms which are eaten by benthos) are the only significant described negative feedbacks acting to counteract the effects of increasing CO2 on a warming planet, together accounting for uptake of ∼10(7) tonnes of carbon per year. Most sea-ice loss to date has occurred over polar continental shelves, which are richly, but patchily, colonised by benthic animals. Most polar benthos feeds on microscopic algae (phytoplankton), which has shown increased blooms coincident with sea-ice losses. Here, growth responses of Antarctic shelf benthos to sea-ice losses and phytoplankton increases were investigated. Analysis of two decades of benthic collections showed strong increases in annual production of shelf seabed carbon in West Antarctic bryozoans. These were calculated to have nearly doubled to >2x10(5) tonnes of carbon per year since the 1980s. Annual production of bryozoans is median within wider Antarctic benthos, so upscaling to include other benthos (combined study species typically constitute ∼3% benthic biomass) suggests an increased drawdown of ∼2.9x10(6) tonnes of carbon per year. This drawdown could become sequestration because polar continental shelves are typically deeper than most modern iceberg scouring, bacterial breakdown rates are slow, and benthos is easily buried. To date, most sea-ice losses have been Arctic, so, if hyperboreal benthos shows a similar increase in drawdown, polar continental shelves would represent Earth's largest negative feedback to climate change. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. The Antarctic - the wild card in the global climate

    International Nuclear Information System (INIS)

    Oesterhus, Svein; Gammelsroed, Tor; Foldvik, Arne; Noest, Ole Anders

    1999-01-01

    The overview gives an account of studies of snowfall, ice melting and formation and water flow patterns in the Antarctic during the present global warming period. It also gives a survey of the ice area in the region. The sea water warming is dramatic and a large floating glacier seems to be decomposing which is disrupting the oceanographic and ecological relations in the region and globally and is significantly influencing the global climate

  14. Observation of very low frequency emissions at Indian Antarctic ...

    Indian Academy of Sciences (India)

    Recently, we have succeeded in recording VLF emissions at the Indian Antarctic station, Maitri (geom. lat. 62° S, geom. long. 57.23°E, =4.5) using a T-type antenna, pre/main amplifiers and digital audio tape recorder. VLF hiss in the frequency ranges 11–13 kHz and 13–14.5 kHz and some riser-type emissions in the ...

  15. Can Antarctic lichens acclimatize to changes in temperature?

    Science.gov (United States)

    Colesie, Claudia; Büdel, Burkhard; Hurry, Vaughan; Green, Thomas George Allan

    2018-03-01

    The Antarctic Peninsula, a tundra biome dominated by lichens and bryophytes, is an ecozone undergoing rapid temperature shifts. Such changes may demand a high physiological plasticity of the local lichen species to maintain their role as key drivers in this pristine habitat. This study examines the response of net photosynthesis and respiration to increasing temperatures for three Antarctic lichen species with different ecological response amplitudes. We hypothesize that negative effects caused by increased temperatures can be mitigated by thermal acclimation of respiration and/or photosynthesis. The fully controlled growth chamber experiment simulated intermediate and extreme temperature increases over the time course of 6 weeks. Results showed that, in contrast to our hypothesis, none of the species was able to down-regulate temperature-driven respiratory losses through thermal acclimation of respiration. Instead, severe effects on photobiont vitality demonstrated that temperatures around 15°C mark the upper limit for the two species restricted to the Antarctic, and when mycobiont demands exceeded the photobiont capacity they could not survive within the lichen thallus. In contrast, the widespread lichen species was able to recover its homoeostasis by rapidly increasing net photosynthesis. We conclude that to understand the complete lichen response, acclimation processes of both symbionts, the photo- and the mycobiont, have to be evaluated separately. As a result, we postulate that any acclimation processes in lichen are species-specific. This, together with the high degree of response variability and sensitivity to temperature in different species that co-occur spatially close, complicates any predictions regarding future community composition in the Antarctic. Nevertheless, our results suggest that species with a broad ecological amplitude may be favoured with on-going changes in temperature. © 2017 John Wiley & Sons Ltd.

  16. Temperature effects on hemocyanin oxygen binding in an antarctic cephalopod.

    Science.gov (United States)

    Zielinski, S; Sartoris, F J; Pörtner, H O

    2001-02-01

    The functional relevance of oxygen transport by hemocyanin of the Antarctic octopod Megaleledone senoi and of the eurythermal cuttlefish Sepia officinalis was analyzed by continuous and simultaneous recordings of changes in pH and hemocyanin oxygen saturation in whole blood at various temperatures. These data were compared to literature data on other temperate and cold-water cephalopods (octopods and giant squid). In S. officinalis, the oxygen affinity of hemocyanin changed at deltaP50/degrees C = 0.12 kPa (pH 7.4) with increasing temperatures; this is similar to observations in temperate octopods. In M. senoi, thermal sensitivity was much smaller (delta log P50/delta pH) increased with increasing temperature in both the cuttlefish and the Antarctic octopod. At low PO2 (1.0 kPa) and pH (7.2), the presence of a large venous oxygen reserve (43% saturation) insensitive to pH reflects reduced pH sensitivity and high oxygen affinity in M. senoi hemocyanin at 0 degrees C. In S. officinalis, this reserve was 19% at pH 7.4, 20 degrees C, and 1.7 kPa O2, a level still higher than in squid. These findings suggest that the lower metabolic rate of octopods and cuttlefish compared to squid is reflected in less pH-dependent oxygen transport. Results of the hemocyanin analysis for the Antarctic octopod were similar to those reported for Vampyroteuthis--an extremely high oxygen affinity supporting a very low metabolic rate. In contrast to findings in cold-adapted giant squid, the minimized thermal sensitivity of oxygen transport in Antarctic octopods will reduce metabolic scope and thereby contribute to their stenothermality.

  17. First record of Babesia sp. in Antarctic penguins.

    Science.gov (United States)

    Montero, Estrella; González, Luis Miguel; Chaparro, Alberto; Benzal, Jesús; Bertellotti, Marcelo; Masero, José A; Colominas-Ciuró, Roger; Vidal, Virginia; Barbosa, Andrés

    2016-04-01

    This is the first reported case of Babesia sp. in Antarctic penguins, specifically a population of Chinstrap penguins (Pygoscelis antarctica) in the Vapour Col penguin rookery in Deception Island, South Shetlands, Antarctica. We collected peripheral blood from 50 adult and 30 chick Chinstrap penguins. Examination of the samples by microscopy showed intraerythrocytic forms morphologically similar to other avian Babesia species in 12 Chinstrap penguin adults and seven chicks. The estimated parasitaemias ranged from 0.25×10(-2)% to 0.75×10(-2)%. Despite the low number of parasites found in blood smears, semi-nested PCR assays yielded a 274 bp fragment in 12 of the 19 positive blood samples found by microscopy. Sequencing revealed that the fragment was 97% similar to Babesia sp. 18S rRNA from Australian Little Penguins (Eudyptula minor) confirming presence of the parasite. Parasite prevalence estimated by microscopy in adults and chicks was higher (24% vs. 23.3%, respectively) than found by semi-nested PCR (16% vs. 13.3% respectively). Although sampled penguins were apparently healthy, the effect of Babesia infection in these penguins is unknown. The identification of Babesia sp. in Antarctic penguins is an important finding. Ixodes uriae, as the only tick species present in the Antarctic Peninsula, is the key to understanding the natural history of this parasite. Future work should address the transmission dynamics and pathogenicity of Babesia sp. in Chinstrap penguin as well as in other penguin species, such as Gentoo penguin (Pygoscelis papua) and Adélie penguin (Pygoscelis adeliae), present within the tick distribution range in the Antarctic Peninsula. Copyright © 2016 Elsevier GmbH. All rights reserved.

  18. Human impacts on Antarctic ecosystems: do not forget the microorganisms!

    OpenAIRE

    Hughes, Kevin; Verleyen, Elie; Vyverman, Wim; Obbels, Dagmar; Willems, Anne; Stelmach Pessi, Igor; Laughinghouse IV, Haywood; Wilmotte, Annick

    2013-01-01

    The tiny and microscopic creatures that are the permanent inhabitants of the Antarctic continent are often overlooked in environmental impact assessments and when new management and protection strategies are designed. This lack of consideration is probably due to their small size and the need of sophisticated molecular methods to study their diversity, evolution and geographic distribution. However, considerable progress has been made in the field of molecular diversity in the last two dec...

  19. 15N and 13C abundances in marine environments with emphasis on biogeochemical structure of food networks

    International Nuclear Information System (INIS)

    Wada, E.

    1987-01-01

    Distributions of δ 15 N and δ 13 C for biogenic substances in the Antarctic Ocean and in the Otsuchi River estuary in Japan were investigated to construct isotope biogeochemical framework for assessing marine ecosystems. The isotopic compositions of phytoplankton were particularly low in the Antarctic Ocean. High nitrate and CO 2 concentrations in the surface sea waters, and the low light intensity seem to enhance the kinetic isotope fractionations that preferred the depletion of 15 N and 13 C in the algal body. A clear-cut linear relationship between animal δ 15 N and its trophic level was obtained in the Antarctic system. In the estuary, the variation of isotope ratios were principally governed by the mixing of land-derived organic matter, marine phytoplankton, and seagrasses. A food-chain effect of 15 N enrichment was also confirmed. An isotopically ordered structure was presented for a marine estuarine ecosystem. The isotopic abundances in a food network vary mainly because of the variation in 15 N and 13 C contents of primary producers grown under different environmental conditions and because of the enrichment of 15 N along food chains. (author)

  20. Mariners Weather Log

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Mariners Weather Log (MWL) is a publication containing articles, news and information about marine weather events and phenomena, worldwide environmental impact...

  1. MarineCadastre.gov

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MarineCadastre.gov is a marine information system that provides authoritative ocean data, offshore planning tools, and technical support to the offshore renewable...

  2. Marine Jurisdiction Boundaries

    Data.gov (United States)

    Department of Homeland Security — The NOAA Coastal Services Center's Marine Jurisdiction dataset was created to assist in marine spatial planning and offshore alternative energy sitting. This is a...

  3. Tsunamis and marine life

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, D.V.S.; Ingole, B.S.; Tang, D.; Satyanarayan, B.; Zhao, H.

    The 26 December 2004 tsunami in the Indian Ocean exerted far reaching temporal and spatial impacts on marine biota. Our synthesis was based on satellite data acquired by the Laboratory for Tropical Marine Environmental Dynamics (LED) of the South...

  4. Supermarket Marine Biology.

    Science.gov (United States)

    Colby, Jennifer A.; And Others

    1995-01-01

    Describes a survey used to determine the availability of intact marine vertebrates and live invertebrates in supermarkets. Results shows that local supermarkets frequently provide a variety of intact marine organisms suitable for demonstrations, experiments, or dissections. (ZWH)

  5. On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

    Directory of Open Access Journals (Sweden)

    Martin Black

    2014-05-01

    Full Text Available The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4 package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE values of 5% in the visible near infrared (0.4–1 µm and 8% in the shortwave infrared (1–2.5 µm. Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation.

  6. Glacial isostatic stress shadowing by the Antarctic ice sheet

    Science.gov (United States)

    Ivins, E. R.; James, T. S.; Klemann, V.

    2005-01-01

    Numerous examples of fault slip that offset late Quaternary glacial deposits and bedrock polish support the idea that the glacial loading cycle causes earthquakes in the upper crust. A semianalytical scheme is presented for quantifying glacial and postglacial lithospheric fault reactivation using contemporary rock fracture prediction methods. It extends previous studies by considering differential Mogi-von Mises stresses, in addition to those resulting from a Coulomb analysis. The approach utilizes gravitational viscoelastodynamic theory and explores the relationships between ice mass history and regional seismicity and faulting in a segment of East Antarctica containing the great Antarctic Plate (Balleny Island) earthquake of 25 March 1998 (Mw 8.1). Predictions of the failure stress fields within the seismogenic crust are generated for differing assumptions about background stress orientation, mantle viscosity, lithospheric thickness, and possible late Holocene deglaciation for the D91 Antarctic ice sheet history. Similar stress fracture fields are predicted by Mogi-von Mises and Coulomb theory, thus validating previous rebound Coulomb analysis. A thick lithosphere, of the order of 150-240 km, augments stress shadowing by a late melting (middle-late Holocene) coastal East Antarctic ice complex and could cause present-day earthquakes many hundreds of kilometers seaward of the former Last Glacial Maximum grounding line.

  7. Peatland Ecosystem Processes in the Maritime Antarctic During Warm Climates.

    Science.gov (United States)

    Loisel, Julie; Yu, Zicheng; Beilman, David W; Kaiser, Karl; Parnikoza, Ivan

    2017-09-27

    We discovered a 50-cm-thick peat deposit near Cape Rasmussen (65.2°S), in the maritime Antarctic. To our knowledge, while aerobic 'moss banks' have often been examined, waterlogged 'peatlands' have never been described in this region before. The waterlogged system is approximately 100 m 2 , with a shallow water table. Surface vegetation is dominated by Warnstorfia fontinaliopsis, a wet-adapted moss commonly found in the Antarctic Peninsula. Peat inception was dated at 2750 cal. BP and was followed by relatively rapid peat accumulation (~0.1 cm/year) until 2150 cal. BP. Our multi-proxy analysis then shows a 2000-year-long stratigraphic hiatus as well as the recent resurgence of peat accumulation, sometime after 1950 AD. The existence of a thriving peatland at 2700-2150 cal. BP implies regionally warm summer conditions extending beyond the mid-Holocene; this finding is corroborated by many regional records showing moss bank initiation and decreased sea ice extent during this time period. Recent peatland recovery at the study site (maritime Antarctic region may promote a more peatland-rich landscape in the future.

  8. Task-dependent cold stress during expeditions in Antarctic environments.

    Science.gov (United States)

    Morris, Drew M; Pilcher, June J; Powell, Robert B

    2017-01-01

    This study seeks to understand the degree of body cooling, cold perception and physical discomfort during Antarctic tour excursions. Eight experienced expedition leaders across three Antarctic cruise voyages were monitored during occupational tasks: kayaking, snorkelling and zodiac outings. Subjective cold perception and discomfort were recorded using a thermal comfort assessment and skin temperature was recorded using a portable data logger. Indoor cabin temperature and outdoor temperature with wind velocity were used as measures of environmental stress. Physical activity level and clothing insulation were estimated using previous literature. Tour leaders experienced a 6°C (2°C wind chill) environment for an average of 6 hours each day. Leaders involved in kayaking reported feeling colder and more uncomfortable than other leaders, but zodiac leaders showed greater skin temperature cooling. Occupational experience did not predict body cooling or cold stress perception. These findings indicate that occupational cold stress varies by activity and measurement methodology. The current study effectively used objective and subjective measures of cold-stress to identify factors which can contribute to risk in the Antarctic tourism industry. Results suggest that the type of activity may moderate risk of hypothermia, but not discomfort, potentially putting individuals at risk for cognitive related mistakes and cold injuries.

  9. Velocities of antarctic outlet glaciers determined from sequential Landsat images

    Science.gov (United States)

    MacDonald, Thomas R.; Ferrigno, Jane G.; Williams, Richard S.; Lucchitta, Baerbel K.

    1989-01-01

    Approximately 91.0 percent of the volume of present-day glacier ice on Earth is in Antarctica; Greenland contains about another 8.3 percent of the volume. Thus, together, these two great ice sheets account for an estimated 99.3 percent of the total. Long-term changes in the volume of glacier ice on our planet are the result of global climate change. Because of the relationship of global ice volume to sea level (± 330 cubic kilometers of glacier ice equals ± 1 millimeter sea level), changes in the mass balance of the antarctic ice sheet are of particular importance.Whether the mass balance of the east and west antarctic ice sheets is positive or negative is not known. Estimates of mass input by total annual precipitation for the continent have been made from scattered meteorological observations (Swithinbank 1985). The magnitude of annual ablation of the ice sheet from calving of outlet glaciers and ice shelves is also not well known. Although the velocities of outlet glaciers can be determined from field measurements during the austral summer,the technique is costly, does not cover a complete annual cycle,and has been applied to just a few glaciers. To increase the number of outlet glaciers in Antarctica for which velocities have been determined and to provide additional data for under-standing the dynamics of the antarctic ice sheets and their response to global climate change, sequential Landsat image of several outlet glaciers were measured.

  10. Expanding Antarctic Sea Ice: Anthropogenic or Natural Variability?

    Science.gov (United States)

    Bitz, C. M.

    2016-12-01

    Antarctic sea ice extent has increased over the last 36 years according to the satellite record. Concurrent with Antarctic sea-ice expansion has been broad cooling of the Southern Ocean sea-surface temperature. Not only are Southern Ocean sea ice and SST trends at odds with expectations from greenhouse gas-induced warming, the trend patterns are not reproduced in historical simulations with comprehensive global climate models. While a variety of different factors may have contributed to the observed trends in recent decades, we propose that it is atmospheric circulation changes - and the changes in ocean circulation they induce - that have emerged as the most likely cause of the observed Southern Ocean sea ice and SST trends. I will discuss deficiencies in models that could explain their incorrect response. In addition, I will present results from a series of experiments where the Antarctic sea ice and ocean are forced by atmospheric perturbations imposed within a coupled climate model. Figure caption: Linear trends of annual-mean SST (left) and annual-mean sea-ice concentration (right) over 1980-2014. SST is from NOAA's Optimum Interpolation SST dataset (version 2; Reynolds et al. 2002). Sea-ice concentration is from passive microwave observations using the NASA Team algorithm. Only the annual means are shown here for brevity and because the signal to noise is greater than in the seasonal means. Figure from Armour and Bitz (2015).

  11. Seashore marine table quiz

    OpenAIRE

    Institute, Marine

    2013-01-01

    Develop an increasing awareness of plants and animals that live in local marine environments including the seashore, seas and oceans of Ireland. After learning all about the seashore and other marine related lessons, this quiz can be used to evaluate the student’s knowledge of the marine related living things and natural environments. The table quiz can be used as a guide, highlighting facts about the marine environment and some of the animals that live there.

  12. Carotenoids in Marine Animals

    OpenAIRE

    Maoka, Takashi

    2011-01-01

    Marine animals contain various carotenoids that show structural diversity. These marine animals accumulate carotenoids from foods such as algae and other animals and modify them through metabolic reactions. Many of the carotenoids present in marine animals are metabolites of β-carotene, fucoxanthin, peridinin, diatoxanthin, alloxanthin, and astaxanthin, etc. Carotenoids found in these animals provide the food chain as well as metabolic pathways. In the present review, I will describe marine a...

  13. Marine Education Knowledge Inventory.

    Science.gov (United States)

    Hounshell, Paul B.; Hampton, Carolyn

    This 35-item, multiple-choice Marine Education Knowledge Inventory was developed for use in upper elementary/middle schools to measure a student's knowledge of marine science. Content of test items is drawn from oceanography, ecology, earth science, navigation, and the biological sciences (focusing on marine animals). Steps in the construction of…

  14. Marine polar steroids

    International Nuclear Information System (INIS)

    Stonik, Valentin A

    2001-01-01

    Structures, taxonomic distribution and biological activities of polar steroids isolated from various marine organisms over the last 8-10 years are considered. The peculiarities of steroid biogenesis in the marine biota and their possible biological functions are discussed. Syntheses of some highly active marine polar steroids are described. The bibliography includes 254 references.

  15. Polar marine ecosystems: major threats and future change

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, A. [British Antarctic Survey, Cambridge (United Kingdom); Harris, C.M. [Environmental Research and Assessment, Grantchester (United Kingdom)

    2003-07-01

    This review of polar marine ecosystems covers both the Arctic and Antarctic, identifying the major threats and, where possible, predicting their possible state(s) in 2025. Although the two polar regions are similar in their extreme photoperiod, low temperatures, and in being heavily influenced by snow and ice, in almost all other respects they are very different. The Arctic Ocean is a basin surrounded by continental landmasses close to, and influenced by, large populations and industrial activities. In contrast, the Southern Ocean is contiguous with all the other great oceans and surrounds a single land mass; Antarctica is remote from major centres of population and sources of pollution. Marine environments in both Polar Regions have been highly disturbed by fishing activity, but, in terms of pollution, some areas remain among the most pristine in the world. There are, however, both local and global pressures. Over the 2025 time horizon, the greatest concern for the Arctic is probably the ecological implications of climate change, particularly insofar as sea ice extent and duration are likely to be affected. Such changes are not expected to be as pronounced in the Southern Ocean over this time period, and concerns are related more to direct threats from harvesting of marine living resources, and the ability to manage these fisheries sustainably. In both Polar Regions, the capacity of marine ecosystems to withstand the cumulative impact of a number of pressures, including climate change, pollution and overexploitation, acting synergistically is of greatest concern. (author)

  16. Rate of egg maturation in marine turtles exhibits 'universal temperature dependence'.

    Science.gov (United States)

    Weber, Sam B; Blount, Jonathan D; Godley, Brendan J; Witt, Matthew J; Broderick, Annette C

    2011-09-01

    1. The metabolic theory of ecology (MTE) predicts that, after correcting for body mass variation among organisms, the rates of most biological processes will vary as a universal function of temperature. However, empirical support for 'universal temperature dependence' (UTD) is currently equivocal and based on studies of a limited number of traits. 2. In many ectothermic animals, the rate at which females produce mature eggs is temperature dependent and may be an important factor in determining the costs of reproduction. 3. We tested whether the rate of egg maturation in marine turtles varies with environmental temperature as predicted by MTE, using the time separating successive clutches of individual females to estimate the rate at which eggs are formed. We also assessed the phenotypic contribution to this rate, by using radio telemetry to make repeated measurements of interclutch intervals for individual green turtles (Chelonia mydas). 4. Rates of egg maturation increased with seasonally increasing water temperatures in radio-tracked green turtles, but were not repeatable for individual females, and did not vary according to maternal body size or reproductive investment (number and size of eggs produced). 5. Using a collated data set from several different populations and species of marine turtles, we then show that a single relationship with water temperature explains most of the variation in egg maturation rates, with a slope that is statistically indistinguishable from the UTD predicted by MTE. However, several alternative statistical models also described the relationship between temperature and egg maturation rates equally parsimoniously. 6. Our results offer novel support for the MTE's predicted UTD of biological rates, although the underlying mechanisms require further study. The strong temperature dependence of egg maturation combined with the apparently weak phenotypic contribution to this rate has interesting behavioural implications in ectothermic

  17. Reconciling projections of the Antarctic contribution to sea level rise

    Science.gov (United States)

    Edwards, Tamsin; Holden, Philip; Edwards, Neil; Wernecke, Andreas

    2017-04-01

    Two recent studies of the Antarctic contribution to sea level rise this century had best estimates that differed by an order of magnitude (around 10 cm and 1 m by 2100). The first, Ritz et al. (2015), used a model calibrated with satellite data, giving a 5% probability of exceeding 30cm by 2100 for sea level rise due to Antarctic instability. The second, DeConto and Pollard (2016), used a model evaluated with reconstructions of palaeo-sea level. They did not estimate probabilities, but using a simple assumption here about the distribution shape gives up to a 5% chance of Antarctic contribution exceeding 2.3 m this century with total sea level rise approaching 3 m. If robust, this would have very substantial implications for global adaptation to climate change. How are we to make sense of this apparent inconsistency? How much is down to the data - does the past tell us we will face widespread and rapid Antarctic ice losses in the future? How much is due to the mechanism of rapid ice loss ('cliff failure') proposed in the latter paper, or other parameterisation choices in these low resolution models (GRISLI and PISM, respectively)? How much is due to choices made in the ensemble design and calibration? How do these projections compare with high resolution, grounding line resolving models such as BISICLES? Could we reduce the huge uncertainties in the palaeo-study? Emulation provides a powerful tool for understanding these questions and reconciling the projections. By describing the three numerical ice sheet models with statistical models, we can re-analyse the ensembles and re-do the calibrations under a common statistical framework. This reduces uncertainty in the PISM study because it allows massive sampling of the parameter space, which reduces the sensitivity to reconstructed palaeo-sea level values and also narrows the probability intervals because the simple assumption about distribution shape above is no longer needed. We present reconciled probabilistic

  18. δ13Catm and [CO2] measurements in Antarctic ice cores, 160 kyrBP - present

    Science.gov (United States)

    Eggleston, Sarah; Schmitt, Jochen; Schneider, Robert; Joos, Fortunat; Fischer, Hubertus

    2014-05-01

    Measurements from Antarctic ice cores allow us to reconstruct atmospheric concentrations of climatically important gases including CO2 over the past 800 kyr. Such measurements show that [CO2] has varied in parallel with Antarctic temperatures on glacial-interglacial timescales. Knowledge of the variations of the stable carbon isotope of CO2, δ13Catm, can help us better understand the processes involved in these fluctuations. Here, we present a first complete δ13Catmrecord extending from 160 kyrBP to the present accompanied by δ15N2 measurements during Marine Isotope Stage 3 (MIS 3, 57 - 29 kyrBP). The present record, measured primarily on ice from the EPICA Dome C and Talos Dome ice cores, has an average resolution of 500 yr, focused mainly on the Last Glacial Maximum and termination (180 yr; Schmitt et al., 2012), MIS 3 (660 yr), and Termination II through MIS 5.4 (590 yr; Schneider et al., 2013). Throughout the record, δ13Catm varies between approximately -6.8 and -6.4‰Following a period of relatively constant δ13Catm at the end of MIS 6 (around -6.8), the boundaries of MIS 5 correspond roughly with the beginning and end of a gradual enrichment in this isotope. In comparison, the more recent record depicts three more abrupt excursions to lighter values around 63 - 59, 46, and 17 kyrBP, in each case followed by a slower return (0.4o over the course of 5 - 15 kyr) to more enriched isotopic values. These coincide with Heinrich events 6, 5, and 1, respectively. No direct correlation is observed between the concentration and carbon isotope of CO2 over the last 160 kyr. The data indicate rather that numerous processes, such as uptake and release of atmospheric CO2 by the ocean and land biosphere, perhaps influenced by regions of growing permafrost during MIS 3 and 4, acting on a variety of timescales must be considered in explaining the evolution of δ13Catm on glacial-interglacial timescales. References: Schmitt, J. et al. Science 336, 711-714 (2012) Schneider

  19. 75 FR 42462 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-07-21

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... Promontory to collect ground control point with highly precise GPS equipment. Activity would include hiking...

  20. 75 FR 53723 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-09-01

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and...-depth sensing equipment is available, however positioning such devices near seabird and pinniped...

  1. 78 FR 76862 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2013-12-19

    ... the Antarctic Science, Tourism and Conservation Act of 1996, has developed regulations for the... in Antarctic waters. Likewise, the sex of individual whales can be determined from genetic markers...

  2. 75 FR 57299 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-09-20

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... spatial scales of various types of disturbances in and around McMurdo Station, Antarctica. The sampling...

  3. 76 FR 61117 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-10-03

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... and spatial scales of various types of disturbances in and around McMurdo Station. The sampling...

  4. 76 FR 20721 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-04-13

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... imaging (MRI) scans. The study, to be conducted in collaboration with the University of California San...

  5. 75 FR 68830 - Notice of permit applications received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-11-09

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... impacts initial CO\\2\\ sequestration and how it impacts the composition of the phytoplankton community...

  6. 77 FR 22004 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2012-04-12

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... educational purposes. Location Palmer Station area, Marguerite Bay including ASPA 107-Dion Islands, ASPA 113...

  7. 77 FR 71842 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2012-12-04

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and..., as well as 500 grams of Artemia salina cysts as food for krill. They plan to measure how fast DNA is...

  8. 78 FR 33115 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2013-06-03

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... pregnancy and future parturition rates; and (3) To what extent might changes in food availability during the...

  9. 77 FR 32701 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2012-06-01

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... overriding incentives is to know how best to conserve this great natural resource of the bird, the food...

  10. 78 FR 58568 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2013-09-24

    ... certain animals and certain geographic areas a requiring special protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas. Application Details 1. Applicant... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic...

  11. 78 FR 53789 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2013-08-30

    ... certain animals and certain geographic areas a requiring special protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas. Application Details 1. Applicant... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic...

  12. Mode change of millennial CO2 variability during the last glacial cycle associated with a bipolar marine carbon seesaw.

    Science.gov (United States)

    Bereiter, Bernhard; Lüthi, Dieter; Siegrist, Michael; Schüpbach, Simon; Stocker, Thomas F; Fischer, Hubertus

    2012-06-19

    Important elements of natural climate variations during the last ice age are abrupt temperature increases over Greenland and related warming and cooling periods over Antarctica. Records from Antarctic ice cores have shown that the global carbon cycle also plays a role in these changes. The available data shows that atmospheric CO(2) follows closely temperatures reconstructed from Antarctic ice cores during these variations. Here, we present new high-resolution CO(2) data from Antarctic ice cores, which cover the period between 115,000 and 38,000 y before present. Our measurements show that also smaller Antarctic warming events have an imprint in CO(2) concentrations. Moreover, they indicate that during Marine Isotope Stage (MIS) 5, the peak of millennial CO(2) variations lags the onset of Dansgaard/Oeschger warmings by 250 ± 190 y. During MIS 3, this lag increases significantly to 870 ± 90 y. Considerations of the ocean circulation suggest that the millennial variability associated with the Atlantic Meridional Overturning Circulation (AMOC) undergoes a mode change from MIS 5 to MIS 4 and 3. Ocean carbon inventory estimates imply that during MIS 3 additional carbon is derived from an extended mass of carbon-enriched Antarctic Bottom Water. The absence of such a carbon-enriched water mass in the North Atlantic during MIS 5 can explain the smaller amount of carbon released to the atmosphere after the Antarctic temperature maximum and, hence, the shorter lag. Our new data provides further constraints for transient coupled carbon cycle-climate simulations during the entire last glacial cycle.

  13. Marine nitrogen cycle

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    ) such as the Marine nitrogen cycle The marine nitrogen cycle. ‘X’ and ‘Y’ are intra-cellular intermediates that do not accumulate in water column. (Source: Codispoti et al., 2001) Page 1 of 3Marine nitrogen cycle - Encyclopedia of Earth 11/20/2006http://www... and nitrous oxide budgets: Moving targets as we enter the anthropocene?, Sci. Mar., 65, 85-105, 2001. Page 2 of 3Marine nitrogen cycle - Encyclopedia of Earth 11/20/2006http://www.eoearth.org/article/Marine_nitrogen_cycle square6 Gruber, N.: The dynamics...

  14. Carotenoids in Marine Animals

    Science.gov (United States)

    Maoka, Takashi

    2011-01-01

    Marine animals contain various carotenoids that show structural diversity. These marine animals accumulate carotenoids from foods such as algae and other animals and modify them through metabolic reactions. Many of the carotenoids present in marine animals are metabolites of β-carotene, fucoxanthin, peridinin, diatoxanthin, alloxanthin, and astaxanthin, etc. Carotenoids found in these animals provide the food chain as well as metabolic pathways. In the present review, I will describe marine animal carotenoids from natural product chemistry, metabolism, food chain, and chemosystematic viewpoints, and also describe new structural carotenoids isolated from marine animals over the last decade. PMID:21566799

  15. Guidelines to Avoid Biocontamination of Antarctic Subglacial Aquatic Environments: Forward Contamination Concerns, Environmental Management and Scientific Stewardship of Icy analogue environments

    Science.gov (United States)

    Race, M. S.; Hobbie, J.; et al.

    2007-12-01

    infancy, the initial methodologies and protocols will undoubtedly continue to need further development and regular revision - making continued collaboration and communication between the polar and space communities mutually beneficial and advisable. NRC Study Committee members: 1 John E. Hobbie (Chair), Marine Biological Laboratory, Woods Hole, Massachusetts; 2 Amy Baker, Technical Administrative Services, Littleton, Colorado; 3 Garry Clarke, The University of British Columbia, Vancouver, Canada; 4 Peter T. Doran, University of Illinois at Chicago, Earth and Environmental Sciences; 5 David Karl, University of Hawaii at Manoa, School of Ocean and Earth Science, Honolulu; 6 Barbara Methé, The Institute for Genomic Research, Rockville, Maryland; 7 Heinz Miller, Alfred-Wegener-Institute for Polar and Marine Research, Germany; 8 Samuel B. Mukasa, University of Michigan, Ann Arbor; 9 Margaret Race, SETI Institute, Mountain View, California; 10 Warwick Vincent, Département de Biologie, Université Laval, Québec, Canada; 11 David Walton, British Antarctic Survey, Cambridge, United Kingdom; 12 James White, University of Colorado, Boulder, 13 Maria Uhle (Study Director), National Research Council.

  16. Marine Robot Autonomy

    CERN Document Server

    2013-01-01

    Autonomy for Marine Robots provides a timely and insightful overview of intelligent autonomy in marine robots. A brief history of this emerging field is provided, along with a discussion of the challenges unique to the underwater environment and their impact on the level of intelligent autonomy required.  Topics covered at length examine advanced frameworks, path-planning, fault tolerance, machine learning, and cooperation as relevant to marine robots that need intelligent autonomy.  This book also: Discusses and offers solutions for the unique challenges presented by more complex missions and the dynamic underwater environment when operating autonomous marine robots Includes case studies that demonstrate intelligent autonomy in marine robots to perform underwater simultaneous localization and mapping  Autonomy for Marine Robots is an ideal book for researchers and engineers interested in the field of marine robots.      

  17. Skin pigmentation provides evidence of convergent melanism in extinct marine reptiles.

    Science.gov (United States)

    Lindgren, Johan; Sjövall, Peter; Carney, Ryan M; Uvdal, Per; Gren, Johan A; Dyke, Gareth; Schultz, Bo Pagh; Shawkey, Matthew D; Barnes, Kenneth R; Polcyn, Michael J

    2014-02-27

    Throughout the animal kingdom, adaptive colouration serves critical functions ranging from inconspicuous camouflage to ostentatious sexual display, and can provide important information about the environment and biology of a particular organism. The most ubiquitous and abundant pigment, melanin, also has a diverse range of non-visual roles, including thermoregulation in ectotherms. However, little is known about the functional evolution of this important biochrome through deep time, owing to our limited ability to unambiguously identify traces of it in the fossil record. Here we present direct chemical evidence of pigmentation in fossilized skin, from three distantly related marine reptiles: a leatherback turtle, a mosasaur and an ichthyosaur. We demonstrate that dark traces of soft tissue in these fossils are dominated by molecularly preserved eumelanin, in intimate association with fossilized melanosomes. In addition, we suggest that contrary to the countershading of many pelagic animals, at least some ichthyosaurs were uniformly dark-coloured in life. Our analyses expand current knowledge of pigmentation in fossil integument beyond that of feathers, allowing for the reconstruction of colour over much greater ranges of extinct taxa and anatomy. In turn, our results provide evidence of convergent melanism in three disparate lineages of secondarily aquatic tetrapods. Based on extant marine analogues, we propose that the benefits of thermoregulation and/or crypsis are likely to have contributed to this melanisation, with the former having implications for the ability of each group to exploit cold environments.

  18. Spatial variation in age structure among colonies of a marine snake: the influence of ectothermy.

    Science.gov (United States)

    Bonnet, Xavier; Brischoux, François; Pinaud, David; Michel, Catherine Louise; Clobert, Jean; Shine, Richard; Fauvel, Thomas

    2015-07-01

    Several tetrapod lineages that have evolved to exploit marine environments (e.g. seals, seabirds, sea kraits) continue to rely upon land for reproduction and, thus, form dense colonies on suitable islands. In birds and mammals (endotherms), the offspring cannot survive without their parents. Terrestrial colonies contain all age classes. In reptiles (ectotherms), this constraint is relaxed, because offspring are independent from birth. Hence, each age class has the potential to select sites with characteristics that favour them. Our studies of sea snakes (sea kraits) in the lagoon of New Caledonia reveal marked spatial heterogeneity in age structure among colonies. Sea krait colonies exhibit the endothermic 'seal-seabird' pattern (mixed-age classes within populations) only where the lagoon is narrow. Where the lagoon is wide, most snake colonies are comprised primarily of a single age cohort. Nurseries are located near the coast, adult colonies offshore and mixed colonies in-between. We suggest that ectothermy allows individuals to utilize habitats that are best suited to their own ecological requirements, a flexibility not available to endothermic marine taxa with obligate parental care. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

  19. 76 FR 39905 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-07-07

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... ASPA 134--Cierva Point and Offshore islands, Danco Coast, Antarctica, to install boreholes and a soil... occurrence and properties, and soil properties along a latitudinal gradient on the western Antarctic...

  20. 75 FR 62891 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-10-13

    ... requiring special protection. The regulations establish such a permit system to designate Antarctic... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  1. 76 FR 52354 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-08-22

    ... requiring special protection. The regulations establish such a permit system to designate Antarctic... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  2. 77 FR 56237 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2012-09-12

    ... protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  3. 75 FR 61520 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-10-05

    ... protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  4. 75 FR 60830 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-10-01

    ... protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  5. 76 FR 58049 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-09-19

    ... protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  6. 75 FR 75501 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-12-03

    ... requiring special protection. The regulations establish such a permit system to designate Antarctic... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... applications received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  7. 75 FR 25300 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-05-07

    ... protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  8. 77 FR 31044 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2012-05-24

    ... protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received Under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  9. 75 FR 6222 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-02-08

    ... protection. The regulations establish such a permit system to designate Antarctic Specially Protected Areas... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received Under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  10. 76 FR 58843 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-09-22

    ... requiring special protection. The regulations establish such a permit system to designate Antarctic... NATIONAL SCIENCE FOUNDATION Notice of Permit Applications Received Under the Antarctic... Applications Received under the Antarctic Conservation Act of 1978, Public Law 95-541. SUMMARY: The National...

  11. Spatial structures in the heat budget of the Antarctic Atmospheric Boundary Layer

    NARCIS (Netherlands)

    van der Berg, W.J.; van den Broeke, M.R.; van Meijgaard, E.

    2008-01-01

    Output from the regional climate model RACMO2/ANT is used to calculate the heat budget of the Antarctic atmospheric boundary layer (ABL). The main feature of the wintertime Antarctic ABL is a persistent temperature deficit compared to the free atmosphere. The magnitude of this deficit is controlled

  12. Contrasting Arctic and Antarctic atmospheric responses to future sea-ice loss

    Science.gov (United States)

    England, M.; Polvani, L. M.; Sun, L.

    2017-12-01

    By the end of this century, the annual mean Antarctic sea ice area is projected to decline by over a third, an amount similar to that in the Arctic, but the effect of Antarctic sea ice loss on the atmosphere remains largely unexplored. Using the Community Earth Systems Model (CESM) Whole Atmosphere Coupled Climate Model (WACCM), we investigate the effect of future Antarctic sea ice loss, and contrast it with its Arctic counterpart. This is accomplished by analyzing integrations of the model with historic and future sea ice levels, using the RCP8.5 scenario. This allows us to disentangle the effect of future sea ice loss on the atmosphere from other aspects of the coupled system. We find that both Antarctic and Arctic sea ice loss act to shift the tropospheric jet equatorwards, counteracting the poleward shift due to increases in greenhouse gases. Although the total forcing to the atmosphere is similar in both hemispheres, the response to Arctic sea ice loss is larger in amplitude and but more seasonally varying, while the response in the Antarctic persists throughout the year but with a smaller amplitude. Furthermore, the atmospheric temperature response over the Antarctic is trapped closer to the surface than in the Arctic, and perhaps surprisingly, we find that the surface temperature response to Antarctic sea ice loss is unable to penetrate the Antarctic continent.

  13. Meltwater produced by wind–albedo interaction stored in an East Antarctic ice shelf

    NARCIS (Netherlands)

    Lenaerts, JTM; Lhermitte, S.L.M.; Drews, R.; Ligtenberg, SRM; Berger, S.; Helm, V.; Smeets, C.J.P.P.; van den Broeke, MR; van de Berg, W.J.; van Meijgaard, E; Eijkelboom, M.; Eisen, O.; Pattyn, F.

    2017-01-01

    Surface melt and subsequent firn air depletion can ultimately lead to disintegration of Antarctic ice shelves1, 2 causing grounded glaciers to accelerate3 and sea level to rise. In the Antarctic Peninsula, foehn winds enhance melting near the grounding line4, which in the recent past has led to the

  14. Spatial pattern in Antarctica: what can we learn from Antarctic bacterial isolates?

    Science.gov (United States)

    Chong, Chun Wie; Goh, Yuh Shan; Convey, Peter; Pearce, David; Tan, Irene Kit Ping

    2013-09-01

    A range of small- to moderate-scale studies of patterns in bacterial biodiversity have been conducted in Antarctica over the last two decades, most suggesting strong correlations between the described bacterial communities and elements of local environmental heterogeneity. However, very few of these studies have advanced interpretations in terms of spatially associated patterns, despite increasing evidence of patterns in bacterial biogeography globally. This is likely to be a consequence of restricted sampling coverage, with most studies to date focusing only on a few localities within a specific Antarctic region. Clearly, there is now a need for synthesis over a much larger spatial to consolidate the available data. In this study, we collated Antarctic bacterial culture identities based on the 16S rRNA gene information available in the literature and the GenBank database (n > 2,000 sequences). In contrast to some recent evidence for a distinct Antarctic microbiome, our phylogenetic comparisons show that a majority (~75 %) of Antarctic bacterial isolates were highly similar (≥99 % sequence similarity) to those retrieved from tropical and temperate regions, suggesting widespread distribution of eurythermal mesophiles in Antarctic environments. However, across different Antarctic regions, the dominant bacterial genera exhibit some spatially distinct diversity patterns analogous to those recently proposed for Antarctic terrestrial macroorganisms. Taken together, our results highlight the threat of cross-regional homogenisation in Antarctic biodiversity, and the imperative to include microbiota within the framework of biosecurity measures for Antarctica.

  15. Standing crop and growth rates of net phytoplankton and nanoplankton in Antarctic waters

    Digital Repository Service at National Institute of Oceanography (India)

    Goes, J.I.; Fondekar, S.P.; Parulekar, A.H.

    stream_size 16 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_419.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_419.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  16. Law 16.518 Antarctic Treaty: approve the protocols about Environment protection and annex s

    International Nuclear Information System (INIS)

    1994-01-01

    The treaty Antarctic in their appendix C in its articles is about the elimination of residuals by means of its removal of the area of having Treated Antarctic among them radioactive materials, planning of the wastes, communication treatment and exam of the plans of treatment of wastes, treatment proceeding prevention of sea contamination ,discharge of hydrocarbons petroliferous, discharge of liquid noxious substances [es

  17. Food choice of Antarctic soil arthropods clarified by stable isotope signatures

    NARCIS (Netherlands)

    Bokhorst, S.F.; Ronfort, C.; Huiskes, A.H.L.; Convey, P.; Aerts, R.A.M.

    2007-01-01

    Antarctic soil ecosystems are amongst the most simplified on Earth and include only few soil arthropod species, generally believed to be opportunistic omnivorous feeders. Using stable isotopic analyses, we investigated the food choice of two common and widely distributed Antarctic soil arthropod

  18. Living resources of Antarctic India's contribution to exploration and future plans for exploration

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    stream_size 7 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_459.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_459.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  19. Zooplankton biomass data collected from net tows from the Eltanin in the Antarctic in support of the US Antarctic Research Program (USARP) from 1963 - 1967 (NODC Accession 0068171)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton biomass data (displacement volume, settled volume) sampled aboard the R/V ELTANIN during the U.S. Antarctic Research Program (USARP) from Apr 5 1963 to...

  20. Oceanographic and topographic conditions structure benthic meiofauna communities in the Weddell Sea, Bransfield Strait and Drake Passage (Antarctic)

    Science.gov (United States)

    Veit-Köhler, Gritta; Durst, Stephan; Schuckenbrock, Jan; Hauquier, Freija; Durán Suja, Laura; Dorschel, Boris; Vanreusel, Ann; Martínez Arbizu, Pedro

    2018-03-01

    The marine environment of the tip of the Antarctic Peninsula is characterised by three oceanographically distinct regions for which we linked continental-slope meiofaunal patterns and environmental drivers on a large scale (100-300 km among ecoregions). Samples for meiofauna communities and sediment analyses were collected with a multicorer, water-column data were derived from water samples and CTD recordings. Meiofauna communities including individuals from 19 higher taxa were compared to a set of 16 environmental variables. We detected significant differences between the communities of Weddell Sea and those of Bransfield Strait and Drake Passage. The amount of phytopigments in the sediment, their freshness and the silt and clay content were driving factors for this separation. The highest meiofauna abundances were found at slopes in the Weddell Sea. Food banks may facilitate high standing stocks. There, the highest ever recorded copepod percentages for the Antarctic were related to the highest phytopigment contents while nematodes were extremely abundant even in deeper sediment layers at stations with fresh organic material. For Bransfield Strait and Drake Passage a sampling scheme of slopes and adjacent troughs was applied. The two regions were divided into three geographical "areas" with the two "habitat" types investigated for each area. Multivariate non-parametric permutational analysis of variance (PERMANOVA) showed that in Bransfield Strait slope and trough meiofauna communities differed significantly in all geographical areas while in Drake Passage this was only the case in the East. These differences were explained best by the regionally and topographically distinct characteristics of 7 out of 11 water-column and sediment-bound factors related to sediment grain size, food quantity and quality, water temperature and salinity. Environmental drivers of the benthic habitat are dependent on large-scale oceanographic conditions and are thus sensitive to changes