Radiolarians reveal past water mass changes at the Sabrina Coast, East Antarctica

Radiolarians are siliceous marine zooplankton found in all of the world’s oceans, inhabiting the entire water column. Their fossilised skeletons, preserved in marine sediments, provide valuable paleoceanographic information due to their distinct depth preferences. In the Southern Ocean, radiolarians preserved in ice-edge marine sediment cores offer a snapshot into  past oceanographic conditions and climatic changes linked to ocean-ice interactions.

Detailed counts of radiolarian taxa have been generated using a sediment core from the Sabrina Coast, East Antarctica. The Sabrina Coast serves as the marine exit point of the Totten Glacier, which is currently thinning due to surface and basal processes. The radiolarian record reveals instances of water mass change on the continental slope during the four most recent interglacial periods (Marine Isotope Stages 1, 5, 7, and 9).

Radiolarian assemblages in this region exhibit greater species richness and diversity than other microfossil groups, such as diatoms and silicoflagellates. Factor analysis highlights that radiolarian assemblages are more dynamic and variable than diatom assemblages during interglacial periods. Fluctuations in the abundance of key radiolarian taxa indicate the presence of intermediate water at times in each interglacial. When paired with subsurface temperature reconstructions, these findings may reveal past periods of basal melting of the Totten Glacier.