Benthic community response to changes in sea-ice cover on the southeastern Weddell Sea shelf, Antarctica.
Supervisors: Santiago Pineda-Metz, Claudio Richter (AWI)
Antarctic marine ecosystems are significantly influenced by the presence of sea-ice, a crucial physical factor. Building upon the well-documented pattern of Antarctic sea-ice cover (sea-ice concentration-SIC) gain (referred to as “Whitening”) from 1979 until 2014, this thesis presents the latest synthesis of physical-biological data, with a specific emphasis on the occurrence of summer SIC loss (referred to as “Blueing”) from 2014 until 2021, in the Filchner region on the southeastern Weddell Sea shelf.

Here, the work provides a description of the benthic communities within this high-Antarctic ecosystem, and assess their relationship with environmental factors. Using seabed image (SBI) data from 24 stations (water depths 300−1780m), four sampled sub-regions were differentiated based on their water mass/sea-ice regime combination: Continental Slope, Eastern Shelf, Filchner Trough and Western Shelf.

The temporal analysis of SIC revealed fluctuating patterns of increase (Whitening) and decrease (Blueing) across the four sampled sub-regions. During the blueing period, noticeable decline in benthic abundances within each subregion was identified. However, colonial organisms underwent contrasting trends compared to non-colonial organisms across subregions and periods. This high temporal faunistic heterogeneity agreed with primary productivity levels delineated in previous research. Benthic abundance negatively correlated with water depth and certain types of sediment (e.g. fine). Its strongly suggested evaluating biomass together with water-mass-related characteristics (e.g. productivity and nutrient regimes, water currents) to clarify benthic spatial distribution patterns.

Key words: Benthic communities, mega-epibenthic fauna, Sea-Ice, Southeastern Weddell Sea, Filchner region, seabed images, environment-benthic relationship