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  • Antarctica  (2)
  • 550.28
  • 2020-2024  (1)
  • 2020-2022  (1)
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  • 2020-2024  (1)
  • 2020-2022  (1)
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  • 1
    Publication Date: 2021-07-03
    Description: The shape of ice shelf cavities are a major source of uncertainty in understanding ice‐ocean interactions. This limits assessments of the response of the Antarctic ice sheets to climate change. Here we use vibroseis seismic reflection surveys to map the bathymetry beneath the Ekström Ice Shelf, Dronning Maud Land. The new bathymetry reveals an inland‐sloping trough, reaching depths of 1,100 m below sea level, near the current grounding line, which we attribute to erosion by palaeo‐ice streams. The trough does not cross‐cut the outer parts of the continental shelf. Conductivity‐temperature‐depth profiles within the ice shelf cavity reveal the presence of cold water at shallower depths and tidal mixing at the ice shelf margins. It is unknown if warm water can access the trough. The new bathymetry is thought to be representative of many ice shelves in Dronning Maud Land, which together regulate the ice loss from a substantial area of East Antarctica.
    Description: Plain Language Summary: Antarctica is surrounded by floating ice shelves, which play a crucial role in regulating the flow of ice from the continent into the oceans. The ice shelves are susceptible to melting from warm ocean waters beneath them. In order to better understand the melting, knowledge of the shape and depth of the ocean cavity beneath ice shelves is crucial. In this study, we present new measurements of the sea floor depth beneath Ekström Ice Shelf in East Antarctica. The measurements reveal a much deeper sea floor than previously known. We discuss the implications of this for access of warm ocean waters, which can melt the base of the ice shelf and discuss how the observed sea floor features were formed by historical ice flow regimes. Although Ekström Ice Shelf is relatively small, the geometry described here is thought to be representative of the topography beneath many ice shelves in this region, which together regulate the ice loss from a substantial area of East Antarctica.
    Description: Key Points: Vibroseis seismic surveys used to map the ice shelf cavity beneath Ekström Ice Shelf in Antarctica. Deep trough with transverse sills and overdeepenings provide evidence of past ice streaming and retreat. Two ocean circulation regimes inferred in the shallow and deep parts of the cavity.
    Description: Belgian Science Policy Contract
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: DFG Cost S2S project
    Description: RD http://dx.doi.org/10.13039/100009936
    Keywords: 550.28 ; 551.31 ; Ice shelf ; Antarctica ; Bathymetry ; Ice‐Ocean Interaction ; Ice dynamics ; Seismics
    Type: article
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  • 2
    Publication Date: 2023-03-02
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Leistenschneider, C., Le Bohec, C., Eisen, O., Houstin, A., Neff, S., Primpke, S., Zitterbart, D., Burkhardt-Holm, P., & Gerdts, G. No evidence of microplastic ingestion in emperor penguin chicks (Aptenodytes forsteri) from the Atka Bay colony (Dronning Maud Land, Antarctica). Science of The Total Environment, (2022): 158314, https://doi.org/10.1016/j.scitotenv.2022.158314.
    Description: Microplastic (〈5 mm; MP) pollution has been an emerging threat for marine ecosystems around the globe with increasing evidence that even the world's most remote areas, including Antarctica, are no longer unaffected. Few studies however, have examined MP in Antarctic biota, and especially those from Antarctic regions with low human activity, meaning little is known about the extent to which biota are affected. The aim of this study was to investigate, for the first time, the occurrence of MP in the emperor penguin (Aptenodytes forsteri), the only penguin species breeding around Antarctica during the austral winter, and an endemic apex predator in the Southern Ocean. To assess MP ingestion, the gizzards of 41 emperor penguin chicks from Atka Bay colony (Dronning Maud Land, Antarctica), were dissected and analyzed for MP 〉500 μm using Attenuated Total Reflection Fourier-transform Infrared (ATR-FTIR) spectroscopy. A total of 85 putative particles, mostly in the shape of fibers (65.9 %), were sorted. However, none of the particles were identified as MP applying state-of-the-art methodology. Sorted fibers were further evidenced to originate from contamination during sample processing and analyses. We find that MP concentrations in the local food web of the Weddell Sea and Dronning Maud Land coastal and marginal sea-ice regions; the feeding grounds to chick-rearing emperor penguin adults, are currently at such low levels that no detectable biomagnification is occurring via trophic transfer. Being in contrast to MP studies on other Antarctic and sub-Antarctic penguin species, our comparative discussion including these studies, highlights the importance for standardized procedures for sampling, sample processing and analyses to obtain comparable results. We further discuss other stomach contents and their potential role for MP detection, as well as providing a baseline for the long-term monitoring of MP in apex predator species from this region.
    Description: This study was supported by the Alfred Wegner Institute (AWI; Germany), the Ricola Foundation (Switzerland), the Freiwillige Akademische Gesellschaft Basel (FAG; Switzerland), the CNRS-France and the RTPI-NUTRESS (CSM Monaco & CNRS University of Strasbourg France).
    Keywords: Aptenodytes forsteri ; Microplastics ; ATR-FTIR ; Stomach content ; Antarctica ; Weddell Sea & Dronning Maud Land
    Repository Name: Woods Hole Open Access Server
    Type: Article
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