Epibenthic distributions patterns at a newfound seamount in the northwestern Weddell Sea (Antarctica)

boris.dorschel [ at ] awi.de


During Polarstern cruise ANT-XXIX/3 a previously unknown and still unnamed seamount was discovered at the deep offshore shelf of the northwestern Weddell Sea in February 2013. During a bathymetric grid survey with Polarstern’s shipboard multibeam system all flanks except for the southeast side (inaccessible due to icebergs) of the structure were covered and mapped in high resolution. The flat plateau area was crossed 4 times along the lengthwise (northwest-southeast) and 4 times across. Even though a full multibeam coverage of the structure was not possible due to ice conditions, the grid survey reveals the morphology of the seamount and allows for an initial interpretation of the influences of icebergs and currents at this seamount. The classification as seamount is based on the overall morphology of the structure that is characteristic for an eroded volcano edifice. It is furthermore supported by pillow lava structures recorded with the shipboard sediment echosounder and igneous rock trawled from the flanks of the mount. Moreover, composition and distribution of the epibenthic megafauna has been investigated by means seabed photographs taken using an Ocean Floor Observation System (OFOFS) along three transects of about two nautical miles each at the northern flank of the seamount, covering the entire depth range from an almost level and very shallow (15-30 m) summit area of approx. 5 nm length and 2 nm width, the steep flank from about 30 to 150 m depth, as well as the more gentle slope to the surrounding shelf plateau of about 400 m depth. First results of the quantitative analysis of the approximately 500 seabed photographs taken per transect, each showing an area of 1.5 x 2.3 m2, will be shown. Further studies are necessary to evaluate whether the mega-epibenthic distribution patterns at the seamount correspond with the effects of iceberg scouring and/or the distribution of morphology-driven circulation cells that may strongly affect pelagic processes such as primary production, sedimentation and, hence, food supply to the benthos.

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Conference (Talk)
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Event Details
XIth Scar Biology Symposium, 14 Jul 2013 - 19 Jul 2013, Barcelona.
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Dorschel, B. , Gutt, J. , Piepenburg, D. and Segelken-Voigt, A. (2013): Epibenthic distributions patterns at a newfound seamount in the northwestern Weddell Sea (Antarctica) , XIth Scar Biology Symposium, Barcelona, 14 July 2013 - 19 July 2013 .

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ANT > XXIX > 3

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