loading page

Long-distance Southern Ocean environmental DNA (eDNA) transect provides insights into spatial marine biota and invasion pathways for non-native species
  • +4
  • Georgia Nester,
  • Leonie Suter,
  • John Kitchener,
  • Michael Bunce,
  • Andrea Polanowski,
  • Johan Wasserman,
  • Bruce Deagle
Georgia Nester
Curtin University

Corresponding Author:[email protected]

Author Profile
Leonie Suter
Australian Antarctic Division
Author Profile
John Kitchener
Australian Antarctic Division
Author Profile
Michael Bunce
Institute of Environmental Science and Research Ltd
Author Profile
Andrea Polanowski
Australian Antarctic Division
Author Profile
Johan Wasserman
Murdoch University Harry Butler Institute
Author Profile
Bruce Deagle
CSIRO
Author Profile

Abstract

The Southern Ocean surrounding Antarctica harbours some of the most pristine marine environments remaining, but is increasingly vulnerable to anthropogenic pressures, climate change, and invasion by non-native species. Monitoring biotic responses to cumulative impacts requires spatiotemporal baselines and ongoing monitoring - traditionally, this has been obtained by continuous plankton recorder (CPR) surveys. Here, we conduct a 3000 nautical mile environmental DNA (eDNA) transect from Hobart (Australia) to Davis Station (Antarctica). We evaluate eDNA sampling strategies for long-term open ocean biomonitoring by comparing two water volume and filter pore size combinations: large (12 L with 20 μm) and small (2 L with 0.45 μm). Employing 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 four simultaneously conducted CPR transects revealed that eDNA detections were more diverse than CPR, with 7 (4 unique) and 4 (1 unique) phyla detections respectively. While both methods effectively delineated biodiversity patterns across the Southern Ocean, eDNA enables surveys in the presence of sea-ice where CPR cannot be conducted. Accordingly, 16 species of concern were detected along the transect using eDNA, notably in the Antarctic region (south of 60°S). These were largely attributed to hull biofouling, a recognized pathway for marine introductions into Antarctica. In a warming Southern Ocean, continued biomonitoring is vital for conserving Antarctic ecosystems. We advocate for the long-term implementation of eDNA metabarcoding alongside CPR surveys to facilitate ecosystem-based management of these vulnerable environments.