Dr Georgia Nester1, Dr Leonie Suter2, Dr Andrea Polanowski2, Dr John Kitchener2, Professor Mike Bunce3, Johan Wasserman4, Dr Bruce Deagle5
1The Minderoo Foundation – OceanOmics Division, Perth, Australia, 2Australian Antarctic Divison, Kingston, Australia, 3Otago University, Dunedin, New Zealand, 4Murdoch University, Murdoch, Australia, 5CSIRO, Hobart, Australia
Biography:
Dr Andrea Polanowski is a researcher within the genetics unit of the Australian Antarctic Division.
Abstract:
The Southern Ocean, surrounding Antarctica, is increasingly vulnerable to anthropogenic pressures, climate change, and invasions by non-native species. Monitoring biotic responses to these impacts requires robust temporal and spatial baselines, generally established through Continuous Plankton Recorder (CPR) surveys. We conducted a 3000-nautical-mile eDNA transect from Hobart, Australia, to Davis Station, Antarctica, evaluating two eDNA sampling strategies: large (12L, 20μm) and small (2L, 0.45μm). Using a broad COI metabarcoding assay, we found the large sample/pore combination was better suited to open ocean monitoring, detecting more target DNA and rare or low abundance species. Comparisons with simultaneously conducted CPR transects (n=4) revealed that eDNA detections were more diverse than CPR, with 7 (4 unique) and 4 (1 unique) phyla detections respectively. While both methods effectively characterised biodiversity patterns across the Southern Ocean, eDNA enabled surveys in the presence of sea-ice where CPR cannot be conducted. Accordingly, eDNA detected 16 species of concern along the transect, notably in the Antarctic region (south of 60°S). These were attributed to hull biofouling, a recognized pathway for marine introductions into Antarctica. Considering the vulnerability of Antarctic environments to potential introductions in a warming Southern Ocean, this research highlights the critical need for sustained biosecurity measures. We propose integrating eDNA metabarcoding with long-term CPR surveys in the Southern Ocean, stressing the urgency of its adoption. The temporal and spatial interweaving of CPR, eDNA, and biophysical data will generate a more nuanced picture of Southern Ocean ecosystems, with significant implications for the conservation and preservation of Antarctic ecosystems.