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  • 1
    Publication Date: 2014-08-20
    Description: Stresses on Antarctic ecosystems result from environmental change, including extreme events, and from (other) human impacts. Consequently, Antarctic habitats are changing, some at a rapid pace while others are relatively stable. A cascade of responses from molecular through organismic to the community level are expected. The differences in biological complexity and evolutionary histories between both polar regions and the rest of the planet suggest that stresses on polar ecosystem function may have fundamentally different outcomes from those at lower latitudes. Polar ecosystem processes are therefore key to informing wider ecological debate about the nature of stability and potential changes across the biosphere. The main goal of AnT-ERA is to facilitate the science required to examine changes in biological processes in Antarctic and sub-Antarctic marine-, freshwater and terrestrial ecosystems. Tolerance limits, as well as thresholds, resistance and resilience to environmental change will be determined. AnT-ERA is classified into three overlapping themes, which represent three levels of biological organisation: (1) molecular and physiological performance, (2) population processes and species traits, (3) ecosystem function and services.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
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  • 2
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 3
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The vertical distribution of bacterial abundance and biomass was investigated in relation to algal biomass in ice cores taken from drifting ice floes in two Arctic shelf areas: the Barents Sea and the Laptev Sea. Bacteria were not homogeneously distributed throughout the cores but occurred in dense layers. Different types of distribution patterns were found: either a single maximum occurred inside or at the bottom of the ice floe or maxima were found in different parts of the floes. Bacterial concentrations ranged from 0.4 to 36.7 · 105 cells ml−1. The size spectra of sea-ice bacteria were determined by image analysis. Cell sizes showed considerable variation between the ice floes. In multi-year sea ice, the largest bacteria were observed in the area of an internal chlorophyll a maximum. No specific vertical distribution patterns were found in first-year ice floes. Bacterial biomass for the ice cores ranged from 19.2 to 79.2 mg C m−2, and the ratio of bacterial:ice algal biomass ranged from 0.43 to 10.42. A comparison with data collected from fast ice revealed large differences in terms of cell size, abundance and biomass.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The occurrence of flagellates and heliozoans in the Greenland Sea was determined from freshly collected samples and crude cultures established during the expedition ARK XI/2 onboard RV “Polarstern” in autumn 1995. The live material was collected from the water column, new ice, and multi-year ice floes, and examined with light (interference and phase contrast) and epifluorescence microscopy. Photographic and video techniques were utilised for the documentation. The observed general morphology of the cells, swimming motions, feeding behaviour and modes of reproduction assisted in the identification of flagellates. A total of 57 photo- and heterotrophic flagellate taxa, representing cryptophytes, dinoflagellates, haptophytes, chrysophytes, Prasinophyceae, chlorophytes, euglenids, choanoflagellates, kinetoplastids, protists of unknown affinity (Protista incertae sedis), and heliozoans, were found. Diatoms were excluded from this study. Newly forming ice, ice floes and cultures established from the ice samples contained almost twice as many identified flagellate taxa as the water column. In addition to general information on the community structure of flagellates and heliozoans, the light microscopical methods used here provided information on the need for additional microscopy, establishment of cultures, and the suitability of the material for experimental work.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acoel Turbellaria constitute a regular component of the metazoa populating Antarctic sea ice (sea-ice endofauna). Two species were collected, which differ in colour, size, shape and egg spawning season. They do not resemble any known pelagic species. Their small body diameter of less than 300 μm allows them to penetrate deeply into the network of brine channels. Their vertical distribution within one ice floe was positively correlated with the accumulation of algal biomass; maxima for both parameters were found in the bottom 5 cm of the floe. The method by which the Turbellaria invade the sea ice is not clear. At present we have no indication that they pass through a pelagic or benthic stage in their life-cycle. As the Turbellaria were found to populate sea ice in areas with water depths ranging from 370 to 4450 m, the presence of benthic phases in their life-cycle, either free-living or epizooic, is not very probable. We suggest that the Turbellaria either use migrating invertebrates as a vector for their propagation or pass through a pelagic stage in their life-cycle.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2020-01-18
    Type: Dataset
    Format: text/tab-separated-values, 363 data points
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  • 7
    Publication Date: 2020-01-18
    Type: Dataset
    Format: text/tab-separated-values, 1666 data points
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  • 8
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    PANGAEA
    In:  Supplement to: Gradinger, Rolf; Bluhm, Bodil A; Iken, Katrin (2010): Arctic sea-ice ridges - Safe heavens for sea-ice fauna during periods of extreme ice melt? Deep Sea Research Part II: Topical Studies in Oceanography, 57(1-2), 86-95, https://doi.org/10.1016/j.dsr2.2009.08.008
    Publication Date: 2020-01-18
    Description: The abundances and distribution of metazoan within-ice meiofauna (13 stations) and under-ice fauna (12 stations) were investigated in level sea ice and sea-ice ridges in the Chukchi/Beaufort Seas and Canada Basin in June/July 2005 using a combination of ice coring and SCUBA diving. Ice meiofauna abundance was estimated based on live counts in the bottom 30 cm of level sea ice based on triplicate ice core sampling at each location, and in individual ice chunks from ridges at four locations. Under-ice amphipods were counted in situ in replicate (N=24-65 per station) 0.25 m**2 quadrats using SCUBA to a maximum water depth of 12 m. In level sea ice, the most abundant ice meiofauna groups were Turbellaria (46%), Nematoda (35%), and Harpacticoida (19%), with overall low abundances per station that ranged from 0.0 to 10.9 ind/l (median 0.8 ind/l). In level ice, low ice algal pigment concentrations (〈0.1-15.8 µg Chl a /l), low brine salinities (1.8-21.7) and flushing from the melting sea ice likely explain the low ice meiofauna concentrations. Higher abundances of Turbellaria, Nematoda and Harpacticoida also were observed in pressure ridges (0-200 ind/l, median 40 ind/l), although values were highly variable and only medians of Turbellaria were significantly higher in ridge ice than in level ice. Median abundances of under-ice amphipods at all ice types (level ice, various ice ridge structures) ranged from 8 to 114 ind/m**2 per station and mainly consisted of Apherusa glacialis (87%), Onisimus spp. (7%) and Gammarus wilkitzkii (6%). Highest amphipod abundances were observed in pressure ridges at depths 〉3 m where abundances were up to 42-fold higher compared with level ice. We propose that the summer ice melt impacted meiofauna and under-ice amphipod abundance and distribution through (a) flushing, and (b) enhanced salinity stress at thinner level sea ice (less than 3 m thickness). We further suggest that pressure ridges, which extend into deeper, high-salinity water, become accumulation regions for ice meiofauna and under-ice amphipods in summer. Pressure ridges thus might be crucial for faunal survival during periods of enhanced summer ice melt. Previous estimates of Arctic sea ice meiofauna and under-ice amphipods on regional and pan-Arctic scales likely underestimate abundances at least in summer because they typically do not include pressure ridges.
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 9
    Publication Date: 2020-01-18
    Type: Dataset
    Format: text/tab-separated-values, 122 data points
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  • 10
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    PANGAEA
    In:  Supplement to: McConnell, Brenna; Gradinger, Rolf; Iken, Katrin; Bluhm, Bodil A (2012): Growth rates of arctic juvenile Scolelepis squamata (Polychaeta: Spionidae) isolated from Chukchi Sea fast ice. Polar Biology, 35(10), 1487-1494, https://doi.org/10.1007/s00300-012-1187-2
    Publication Date: 2020-01-18
    Description: In spring, Arctic coastal fast ice is inhabited by high densities of sea ice algae and, among other fauna, juveniles of benthic polychaetes. This paper investigates the hypothesis that growth rates of juveniles of the common sympagic polychaete, Scolelepis squamata (Polychaeta: Spionidae), are significantly faster at sea ice algal bloom concentrations compared to concurrent phytoplankton concentrations. Juvenile S. squamata from fast ice off Barrow, Alaska, were fed with different algal concentrations at 0 and 5 °C, simulating ambient high sea ice algal concentrations, concurrent low phytoplankton concentrations, and an intermediate concentration. Growth rates, calculated using a simple linear regression equation, were significantly higher (up to 115 times) at the highest algal concentration compared to the lowest. At the highest algal concentration, juveniles grew faster at 5 °C compared to those feeding at 0 °C with a Q10 of 2.0. We conclude that highly concentrated sea ice algae can sustain faster growth rates of polychaete juveniles compared to the less dense spring phytoplankton concentrations. The earlier melt of Arctic sea ice predicted with climate change might cause a mismatch between occurrence of polychaete juveniles and food availability in the near future. Our data indicate that this reduction in food availability might counteract any faster growth of a pelagic juvenile stage based on forecasted increased water temperatures.
    Type: Dataset
    Format: text/tab-separated-values, 84 data points
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