Dinoflagellates in a fast-ice covered inlet of the Riiser-Larsen Ice Shelf (Weddell Sea)

A short-term (3–15 days) multiple and single sediment-trap array deployed in Drescher Inlet (Eastern Weddell Sea) during austral summer 1998 showed well preserved and relatively diverse dinoflagellate assemblages comprised of 13 taxa. Consistent with other Antarctic studies, large Protoperidinium species were dominating whereas Preperidinium and Dinophysis showed minor frequencies. Athecates were not observed, possibly due to their poor preservation status. The majority of dinoflagellates were heterotrophic species, likely feeding on previously recorded abundant diatoms at the study site. Assemblage structures varied according to depth (Protoperidinium antarcticum and P. rosaceum at 10 m depth vs. P. macrapicatum and Preperidinium granulosum at 360 m depth) and collection period (first period: P. antarcticum; second period: Protoperidinium sp. C). Sediment-trap dinoflagellates were either derived from a flux out of the overlying fast ice, platelet ice, or the water column but given their high mobility, migration between these media cannot be ruled out.