ALBERT

Description: Due to extreme pack ice, the Filchner Region in the southern Weddell Sea is one of the least studied regions on the planet. Here, we provide a detailed description of the benthic communities of this high-Antarctic ecosystem, and assess the relationship between environmental factors and benthic distribution patterns. Fieldwork was performed in the austral summers of 2013-14 and 2015-16 during the R/V 'Polarstern' cruises PS82 and PS96. Using a combination of multibox corer (MBC) and seabed image data from 37 stations (water depths 243-1217 m), we differentiated 6 station groups. While 1 of these groups was comprised of a single station, the other 5 groups represented distinct benthic communities. Three of these correspond to the previously described Eastern Shelf, Southern Shelf, and Southern Trench communities. However, we found distribution shifts and MBC abundance and biomass reductions when comparing our results with earlier studies. The other 2 groups have novel characteristics and are presented here as an Ice/Ice Shelf Water-related community and a Continental slope community. Water depth in combination with 2 or 3 other environmental variables (out of 7 available) explained 〈30% of the benthic distribution and composition. We found a tighter relationship between water mass circulation and spatial distribution of the communities; we suggest using water-mass-related characteristics (e.g. productivity regimes, water currents) to better explain benthic spatial distribution patterns.

Description: Imagery transects with a camera attached to a multibox corer providing seabed images were carried out during POLARSTERN expedition ANT-XXIX/9 (PS82) focussing on the ecology of benthic assemblages on the southern and eastern Weddell Sea shelves. The camera system attached to the multibox corer was composed of one casing housing a Cannon EOS 100 camera, a second casing housing a flash-light, two lights fixed to the multibox corer frame, and 4.5cm distanced parallel lasers providing a scale in the images. The camera was tilted to a 45° angle. The transects were done along the drift trail of the ship, maximum speed was 1knot, and minimum speed varied with current speed. The winch of the ship was used to maintain a distance of approximately 1-2m above the seabed. The seabed images provide insights into the general composition of key species, higher systematic groups and ecological guilds. Within interdisciplinary approaches, distributions of assemblages can be attributed to environmental conditions such as bathymetry, sediment characteristics, water masses and current regimes. The images also contain valuable information on how benthic species are associated to each other. Transect files include individual images, whereas metadata of each image is found in a separate file. Geographical coordinates of images was based on the Posidonia system of the telemetry box attached to the multibox corer. Due to technical problems, St-033 and 044 were carried without Posidonia, thus Latitude and Longitude for each image is unavailable. For all other transects the Posidonia system was functional and, with a few exceptions, most images have their corresponding Latitude and Longitude.