TrEnD Laboratory, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia.
Australian Antarctic Division, Department of Climate Change, Energy, the Environment and Water, Kingston, Tasmania, Australia.
Sci Total Environ. 2024 Nov 15;951:175657. doi: 10.1016/j.scitotenv.2024.175657. Epub 2024 Aug 22.
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.
环绕南极洲的南大洋拥有一些仍然保持原始状态的海洋环境，但越来越容易受到人为压力、气候变化和非本地物种入侵的影响。监测生物对累积影响的反应需要时间和空间的基线和持续监测——传统上，这是通过连续浮游生物记录器（CPR）调查获得的。在这里，我们进行了一次最长的环境 DNA（eDNA）横截线之一，从霍巴特（澳大利亚）到戴维斯站（南极洲）跨越了 3000 多海里。我们通过比较两种水体积和滤膜孔径组合来评估长期开放海洋生物监测的 eDNA 采样策略：大（12 l 用 20 μm）和小（2 l 用 0.45 μm）。采用广泛的 COI 代谢组学分析，我们发现大样本/孔组合更适合开放海洋监测，可检测到更多目标 DNA 和稀有或低丰度物种。与同时进行的四个 CPR 横截线的比较表明，eDNA 检测的多样性比 CPR 更高，分别检测到 7 个（4 个独特）和 4 个（1 个独特）门。虽然两种方法都有效地描绘了南大洋的生物多样性模式，但 eDNA 可以在 CPR 无法进行的情况下进行调查。因此，使用 eDNA 在横截线上检测到了 16 种受关注的物种，特别是在南极地区（南纬 60°S 以南）。这些主要归因于船体生物污垢，这是海洋引入南极洲的一种公认途径。考虑到南极环境在变暖的南大洋中对潜在引入物的脆弱性，这项工作强调了持续生物安全警惕的重要性。我们主张将 eDNA 代谢组学与南大洋的长期 CPR 调查相结合，强调其实施的紧迫性。我们预计 CPR、eDNA 和生物物理数据的时间和空间交织将更细致地描绘南大洋生态系统的情况，对保护和维护南极生态系统具有重要意义。
