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Long-distance Southern Ocean environmental DNA (eDNA) transect provides insights into spatial marine biota and invasion pathways for non-native species
Journal article   Open access   Peer reviewed

Long-distance Southern Ocean environmental DNA (eDNA) transect provides insights into spatial marine biota and invasion pathways for non-native species

Georgia M. Nester, Leonie Suter, John A. Kitchener, Michael Bunce, Andrea M. Polanowski, Johan Wasserman and Bruce Deagle
The Science of the total environment, Vol.951, 175657
2024
DOI: https://doi.org/10.1016/j.scitotenv.2024.175657
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Published3.72 MBDownloadView
CC BY V4.0,  Open Access

Abstract

Antarctic Biodiversity Biomonitoring Biosecurity Continuous plankton recorder Metabarcoding
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 temporal and spatial baselines and ongoing monitoring - traditionally, this has been obtained by continuous plankton recorder (CPR) surveys. Here, we conduct one of the longest environmental DNA (eDNA) transects yet, spanning over 3000 nautical miles 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. Given the vulnerability of Antarctic environments to potential introductions in a warming Southern Ocean, this work underscores the importance of continued biosecurity vigilance. We advocate integrating eDNA metabarcoding with long-term CPR surveys in the Southern Ocean, emphasising the urgency of its implementation. We anticipate 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. [Display omitted] •We assessed eDNA for long-term biomonitoring in Southern Ocean and compared with CPR.•Larger volumes and pore sizes better suited for open-ocean eDNA monitoring•All methods detect unique taxa, but only eDNA can be used in presence of sea-ice.•Consequently 16 species of concern were detected, attributed to hull biofouling.•eDNA crucial for ongoing biosecurity vigilance in the Southern Ocean

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