Sedimentary ancient DNA as an environmental proxy in Antarctic fjords

The potential of sedimentary ancient DNA (sedaDNA) as a new tool for tracing sea ice and environmental conditions over the Anthropocene was investigated in a fjord on the Western Antarctic Peninsula, a climate warming hotspot. A short marine sediment core of 25 cm length from the fjord (Sheldon Cove) was analysed for sedaDNA at 1 to 2 cm intervals. The core, taken in 2018, was dated by 210Pb which indicates that it extends to ~1890 CE. We focussed on sedaDNA of the obligate sympagic (sea-ice-affiliated) dinoflagellate Polarella glacialis and the dinoflagellate Islandinium minutum, a taxon routinely used for past sea-ice reconstructions, but one that also occurs in year-round sea-ice-free areas. We also noted important marine foodweb components such as diatoms and dinoflagellates.