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  • 11
    Publication Date: 2017-07-14
    Description: Marine habitats worldwide are increasingly pressurized by climate change, especially along the Antarctic Peninsula. Well-studied areas in front of rapidly retreating tidewater glaciers like Potter Cove are representative for similar coastal environments and, therefore, shed light on habitat formation and development on not only a local but also regional scale. The objective of this study was to provide insights into habitat distribution in Potter Cove, King George Island, Antarctica, and to evaluate the associated environmental processes. Furthermore, an assessment concerning the future development of the habitats is provided. To describe the seafloor habitats in Potter Cove, an acoustic seabed discrimination system (RoxAnn) was used in combination with underwater video images and sediment samples. Due to the absence of wave and current measurements in the study area, bed shear stress estimates served to delineate zones prone to sediment erosion. On the basis of the investigations, two habitat classes were identified in Potter Cove, namely soft-sediment and stone habitats that, besides influences from sediment supply and coastal morphology, are controlled by sediment erosion. A future expansion of the stone habitat is predicted if recent environmental change trends continue. Possible implications for the Potter Cove environment, and other coastal ecosystems under similar pressure, include changes in biomass and species composition.
    Type: Article , PeerReviewed
    Format: text
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  • 12
    Publication Date: 2023-02-08
    Description: To reconstruct the climatic and paleoceanographic variability offshore Northeast Greenland during the last ~10 ka with multidecadal resolution, sediment core PS93/025 from the outermost North-East Greenland continental shelf (80.5°N) was studied by a variety of micropaleontological, sedimentological and isotopic methods. High foraminiferal fluxes, together with high proportions of ice-rafted debris and high Ca/Fe ratios, indicate a maximum in bioproductivity until ~8 ka related to a low sea-ice coverage. Sortable silt values, planktic foraminifer associations, and stable isotope data of planktic and benthic foraminifers suggest a strong westward advection of relatively warm Atlantic Water by the Return Atlantic Current during this time, with a noticeable bottom current activity. This advection may have been facilitated by a greater water depth at our site, resulting from postglacial isostatic depression. For the following mid-Holocene interval (ca. 8–5 ka), isotope data, lower foraminiferal fluxes and a shift in grain size maxima point to a lasting but successively decreasing Atlantic Water inflow, a weakening productivity, and a growing sea-ice coverage which is also revealed by the P III IP 25 index. A final stage in the environmental development was reached at ~5 ka with the establishment of pre-industrial conditions. Low Ca/Fe ratios, low foraminiferal fluxes, low sortable silt values and the sea-ice indicating P III IP 25 index point to a limited productivity and a weak Atlantic Water inflow by the Return Atlantic Current to our research area, as well as a higher and/or seasonally more extended sea-ice coverage during the Late Holocene. Two intervals with somewhat enhanced Atlantic Water advection around 2.0 and 1.0 ka are indicated by slightly increased foraminiferal fluxes and the reoccurrence of subpolar foraminifers. These intervals may correlate with the Roman Warm Period and the Medieval Climate Anomaly, as defined in the North Atlantic region.
    Type: Article , PeerReviewed
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  • 13
    Publication Date: 2019-06-11
    Description: Strandings of marine animals are relatively common in marine systems. However, the underlying mechanisms are poorly understood. We observed mass strandings of krill in Antarctica that appeared to be linked to the presence of glacial meltwater. Climate-induced glacial meltwater leads to an increased occurrence of suspended particles in the sea, which is known to affect the physiology of aquatic organisms. Here, we study the effect of suspended inorganic particles on krill in relation to krill mortality events observed in Potter Cove, Antarctica, between 2003 and 2012. The experimental results showed that large quantities of lithogenic particles affected krill feeding, absorption capacity and performance after only 24 h of exposure. Negative effects were related to both the threshold concentrations and the size of the suspended particles. Analysis of the stomach contents of stranded krill showed large quantities of large particles ( 〉 106 μm3), which were most likely mobilized by glacial meltwater. Ongoing climate-induced glacial melting may impact the coastal ecosystems of Antarctica that rely on krill.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: video
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  • 14
    Publication Date: 2019-06-11
    Description: Since the Last Glacial Maximum, ice has retreated through the fjords of the South Shetland Islands leaving a valuable record of submarine landforms behind. In this study, glacial landforms and sub-bottom characteristics have been mapped to investigate the late Holocene retreat behaviour of the Fourcade Glacier and to delineate past environmental processes in Potter Cove, King George Island. The comprehensive datasets include high-resolution swath bathymetry, shallow seismic profiling and one sediment core. Moraines, moraine incisions and glacial lineations were mapped on the sea floor in the inner part of the cove, whereas pockmarks, ice scour marks and channel structures were identified in the outer part. Sub-bottom characteristics have been assigned to different acoustic facies types indicating different depositional settings. The results reveal glacial recessions as well as stillstands and potential readvances during the late Holocene. Furthermore, the sediment record indicates that the Fourcade Glacier was situated inside the inner cove during the Little Ice Age (500–100 cal yr bp).
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 15
    Publication Date: 2024-02-07
    Description: The Antarctic Circumpolar Current (ACC) plays a crucial role in global ocean circulation by fostering deep-water upwelling and formation of new water masses. On geological time-scales, ACC variations are poorly constrained beyond the last glacial. Here, we reconstruct changes in ACC strength in the central Drake Passage in vicinity of the modern Polar Front over a complete glacial-interglacial cycle (i.e., the past 140,000 years), based on sediment grain-size and geochemical characteristics. We found significant glacial-interglacial changes of ACC flow speed, with weakened current strength during glacials and a stronger circulation in interglacials. Superimposed on these orbital-scale changes are high-amplitude millennial-scale fluctuations, with ACC strength maxima correlating with diatom-based Antarctic winter sea-ice minima, particularly during full glacial conditions. We infer that the ACC is closely linked to Southern Hemisphere millennial-scale climate oscillations, amplified through Antarctic sea ice extent changes. These strong ACC variations modulated Pacific-Atlantic water exchange via the “cold water route” and potentially affected the Atlantic Meridional Overturning Circulation and marine carbon storage.
    Type: Article , PeerReviewed
    Format: text
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  • 16
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    PANGAEA
    In:  Alfred Wegener Institute - Wadden Sea Station Sylt
    Publication Date: 2023-03-16
    Keywords: Aircraft; AWI_Coast; Coastal Ecology @ AWI; DATE/TIME; LATITUDE; LONGITUDE; MULT; Multiple investigations; Sylt_image; Sylt air photographs; Sylter Wattenmeer; Uniform resource locator/link to raw data file; UTM Easting, Universal Transverse Mercator; UTM Northing, Universal Transverse Mercator; UTM Zone, Universal Transverse Mercator
    Type: Dataset
    Format: text/tab-separated-values, 825 data points
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  • 17
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    PANGAEA
    In:  Alfred Wegener Institute - Wadden Sea Station Sylt
    Publication Date: 2023-03-16
    Keywords: Aircraft; AWI_Coast; Coastal Ecology @ AWI; DATE/TIME; LATITUDE; LONGITUDE; MULT; Multiple investigations; Sylt_image; Sylt air photographs; Sylter Wattenmeer; Uniform resource locator/link to raw data file; UTM Easting, Universal Transverse Mercator; UTM Northing, Universal Transverse Mercator; UTM Zone, Universal Transverse Mercator
    Type: Dataset
    Format: text/tab-separated-values, 740 data points
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  • 18
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    PANGAEA
    In:  Alfred Wegener Institute - Wadden Sea Station Sylt
    Publication Date: 2023-03-16
    Keywords: Aircraft; AWI_Coast; Coastal Ecology @ AWI; DATE/TIME; LATITUDE; LONGITUDE; MULT; Multiple investigations; Sylt_image; Sylt air photographs; Sylter Wattenmeer; Uniform resource locator/link to raw data file; UTM Easting, Universal Transverse Mercator; UTM Northing, Universal Transverse Mercator; UTM Zone, Universal Transverse Mercator
    Type: Dataset
    Format: text/tab-separated-values, 740 data points
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  • 19
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    PANGAEA
    In:  Alfred Wegener Institute - Wadden Sea Station Sylt
    Publication Date: 2023-03-16
    Keywords: Aircraft; AWI_Coast; Coastal Ecology @ AWI; DATE/TIME; LATITUDE; LONGITUDE; MULT; Multiple investigations; Sylt_image; Sylt air photographs; Sylter Wattenmeer; Uniform resource locator/link to raw data file; UTM Easting, Universal Transverse Mercator; UTM Northing, Universal Transverse Mercator; UTM Zone, Universal Transverse Mercator
    Type: Dataset
    Format: text/tab-separated-values, 2065 data points
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  • 20
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    PANGAEA
    In:  Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven
    Publication Date: 2023-03-16
    Keywords: Calculated; Course; CT; DATE/TIME; HE439; HE439-track; Heincke; LATITUDE; LONGITUDE; North Sea; Speed; Underway cruise track measurements
    Type: Dataset
    Format: text/tab-separated-values, 5470 data points
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