Description: The crabeater seal (Lobodon carcinophaga) is the most abundant Antarctic seal and inhabits the circumpolar pack ice zone of the Southern Ocean. Until now, information on important environmental factors affecting its distribution as well as on foraging behaviour is limited. In austral summer 1998, 12 crabeater seals of both sexes and different age classes were equipped with satellitelinked dive recorders at Drescher Inlet (72.85°S, 19.26°E), eastern Weddell Sea. To identify suitable habitat conditions within the Weddell Sea, a maximum entropy (Maxent) modelling approach was implemented. The model revealed that the eastern and southern Weddell Sea is especially suitable for crabeater seals. Distance to the continental shelf break and sea ice concentration were the two most important parameters in modelling species distribution throughout the study period. Model predictions demonstrated that crabeater seals showed a dynamic response to their seasonally changing environment emphasized by the favoured sea ice conditions. Crabeater seals utilized ice-free waters substantially, which is potentially explained by the comparatively low sea ice cover of the Weddell Sea during summer 1998. Diving behaviour was characterized by short (〉90 % = 0-4 min) and shallow (〉90 % = 0-51 m) dives. This pattern reflects the typical summer and autumn foraging behaviour of crabeater seals. Both the distribution and foraging behaviour corresponded well with the life history of the Antarctic krill (Euphausia superba), the preferred prey of crabeater seals. In general, predicted suitable habitat conditions were congruent with probable habitats of krill, which emphasizes the strong dependence on their primary prey.

Description: Sea floor morphology plays an important role in many scientific disciplines such as ecology, hydrology and sedimentology since geomorphic features can act as physical controls for e.g. species distribution, oceanographically flow-path estimations or sedimentation processes. In this study, we provide a terrain analysis of the Weddell Sea based on the 500 m × 500 m resolution bathymetry data provided by the mapping project IBCSO. Seventeen seabed classes are recognized at the sea floor based on a fine and broad scale Benthic Positioning Index calculation highlighting the diversity of the glacially carved shelf. Beside the morphology, slope, aspect, terrain rugosity and hillshade were calculated. Applying zonal statistics to the geomorphic features identified unambiguously the shelf edge of the Weddell Sea with a width of 45-70 km and a mean depth of about 1200 m ranging from 270 m to 4300 m. A complex morphology of troughs, flat ridges, pinnacles, steep slopes, seamounts, outcrops, and narrow ridges, structures with approx. 5-7 km width, build an approx. 40-70 km long swath along the shelf edge. The study shows where scarps and depressions control the connection between shelf and abyssal and where high and low declination within the scarps e.g. occur. For evaluation purpose, 428 grain size samples were added to the seabed class map. The mean values of mud, sand and gravel of those samples falling into a single seabed class was calculated, respectively, and assigned to a sediment texture class according to a common sediment classification scheme.

Description: Interests in exploring Cold Water Corals (CWC) ecosystems witnessed a dramatic increase in the last decades, after the realisation that their habitats are threatened by ocean warming and acidification. However, they are still largely overlooked by the scientific community in deep and harsh environments like the Southern Ocean. Recent advances in species distribution models (SDM) have allowed forecasting species distribution patterns and assessing climate change impacts at different spatial scales. Several limitations related to the accuracy of species presences, the lack of reliable absence data and the limited spatial resolution of environmental factors, have restricted the widespread utilisation of these approaches in polar areas. In this work, real presence-absence records of 13 species were gathered from research expeditions and literature and combined with model-generated pseudo-absences, to cover the study area. Moreover, a final set of 14 high-resolution environmental variables was pre-selected and nine species distribution modelling algorithms were merged with means of the ensemble forecasting platform 'biomod2' to model the habitat suitability for azooxanthallate scleractinian corals, in the Weddell Sea. 'Biomod2' is implemented in 'R' and is a freeware, open source package. Response of scleractinian distribution to the future climate change was also investigated, based on two future scenarios of the bottom sea temperature. Present ensemble prediction maps accurately captured the potential ecological niches of the modelled species (good to excellent true skill statistic (TSS) and area under the receiver operating characteristic curve (AUC) evaluation measures). In the Weddell Sea, scleractinian distribution is limited to the continental shelf and slope areas with preference to small scale features (i.e., seamounts), which have been identified as having a high probability of supporting cold-water coral habitat. The most important factors in determining CWC habitat suitability were distance to coast and ice shelves, bathymetry, calcium carbonate and temperature. The response of scleractinian to future climate revealed some changes in small-scale spatial distribution patterns. Under warmer conditions, the CWC will probably expand their distribution range by a total of 6 to 10%, by 2037 and 2150 respectively, compared to the present. This expansion would concern the Filchner Trough and the adjacent continental shelves as well as the eastern side of the Antarctic Peninsula.

Description: Species distribution models (SDM) predict species occurrence based on statistical relationships with environmental conditions. The R-package biomod2 which includes 10 different SDM techniques and 10 different evaluation methods was used in this study. Macroalgae are the main biomass producers in Potter Cove, King George Island (Isla 25 de Mayo), Antarctica, and they are sensitive to climate change factors such as suspended particulate matter (SPM). Macroalgae presence and absence data were used to test SDMs suitability and, simultaneously, to assess the environmental response of macroalgae as well as to model four scenarios of distribution shifts by varying SPM conditions due to climate change. According to the averaged evaluation scores of Relative Operating Characteristics (ROC) and True scale statistics (TSS) by models, those methods based on a multitude of decision trees such as Random Forest and Classification Tree Analysis, reached the highest predictive power followed by generalized boosted models (GBM) and maximum-entropy approaches (Maxent). The final ensemble model used 135 of 200 calculated models (TSS 〉 0.7) and identified hard substrate and SPM as the most influencing parameters followed by distance to glacier, total organic carbon (TOC), bathymetry and slope. The climate change scenarios show an invasive reaction of the macroalgae in case of less SPM and a retreat of the macroalgae in case of higher assumed SPM values.

Description: FOR DOWNLOAD THE COMPLETE FILE PLEASE USE THE "OTHER VERSION". 363322 values, 1037 CTD profiles (Conductivity, Temperature & Density), salinity, voltage and pressure data compiled at 123 stations, spatially distribute in entire Potter Cove. Variable available: Coordinates of stations, depth sampling [m], water temperature [°C], potential temperature [°C], salinity [psu], density [kg/m^3], conductivity [mS/cm], turbidity [NTU], voltage [V], press [dbar].The depth has been classified into three categories 0-5 m; 5-15 m and over 15 m. 5 stations were monthly sampled: E1, E2, E3 (18, 17, 6 years, respectively); Faro and Peñon de Pesca (all months except June & July for 2 and 3 years, respectively). The other 118 stations belong to summer season only covering 1 to 5 years sampling. Transects for summer 1996/1997, 2007 and 2008 have been georeferenced and newly available. Device used: CTD/Rosette (CTD-RO).

Description: Suspended particulate matter (SPM), inorganic particulate matter (IPM) and organic particulate matter (OPM) of 55 stations in water and 19 on land joined with meteorological variables (daily mean, maximum and minimum air temperature; daily range temperature 'max-min'); atmospheric pressure; relative humidity; precipitation; visibility; mean and max wind speed of day; wind gut; direction and cloud cover ) in Potter Cove, Carlini Station, King George Island (Isla 25 de Mayo). The depth has been classified into three categories: 0-5 m; 5-15 m and over 15 m.

Description: FOR DOWNLOAD THE COMPLETE FILE PLEASE USE THE "OTHER VERSION". A joined data set of CTD profiles (conductivity, temperature, density, salinity, voltage and pressure) with metereological variables (daily mean, maximum and minimum air temperature; daily range temperature ?max-min); atmospheric pressure; relative humidity; precipitation; visibility; mean and max wind speed of day; wind gut; direction and cloud cover ) in Potter Cove, Carlini Station, King George Island (Isla 25 de Mayo). Stations have been merged within a neighbourhood of 0-100 m and concerning their membership to a geochemical cluster analysis (https://doi.pangaea.de/10.1594/PANGAEA.856971). 85 stations are remaining from the original data set (doi parent). The depth has been classified into three categories: 0-5 m; 5-15 m and over 15 m. Comment: As soon as there are CTD sample without metereology abailable it exists empty rows. Device used: CTD/Rosette (CTD-RO).