Table2_eDNA analysis reveals high invasion risks in nature reserves in Guangdong Province, China.xlsx

IntroductionInvasive species can cause ecological and economic damage in various areas, including nature reserves. The invasion risks of aquatic invasive vertebrates in nature reserves, however, remain unclear since this group often hides under the water and is frequently neglected in ecological surveys based on traditional methods.
MethodsEnvironmental DNA (eDNA) provides a promising alternative way to conduct biodiversity surveys in aquatic ecosystems. Here, we collected aquatic eDNA samples from eight nature reserves in Guangdong Province, China to mainly investigate the diversity of aquatic invasive vertebrates and inform their invasion risks in these nature reserves.
Results and discussionWe detected a total of 104 aquatic vertebrate species belonging to three classes (Actinopteri, Amphibia and Reptilia), 12 orders, 32 families, and 71 genera, among which nine were invasive species (8.65% of all aquatic vertebrates detected), i.e., Coptodon zillii, Sarotherodon galilaeus, Oreochromis niloticus, Oreochromis tanganicae, Gambusia affinis, Clarias gariepinus, Chelydra serpentina, Trachemys scripta elegans, and Rana catesbeiana. Surprisingly, 55.56% of these aquatic invasive vertebrates (i.e., five species) were found in at least 75.00% samples, and both C. zillii and S. galilaeus were detected in all samples (100%), suggesting that most invasive species were widely distributed in these nature reserves. In addition, all aquatic invasive vertebrate species ranked very high (top 66 of aquatic vertebrates detected) regarding their relative abundance of sequences, and three of the top 10 species with the highest number of sequences were invasive species (i.e., C. zillii, S. galilaeus, and O. niloticus), suggesting high population size of these invasive vertebrates. Moreover, we also detected 16 endangered/threatened species (15.38% of all vertebrates detected), which demonstrated notable overlaps of geographic distribution with invasive species. The reality of high abundance, wide geographical distribution and overlaps with the endangered/threatened species indicated considerable risks of aquatic invasive vertebrates in nature reserves in Guangdong Province, which calls for urgent needs for effective management. Our study would provide fundamental insights for the formulation of effective management measures to reduce losses caused by invasive species and promote the protection of endangered/threatened species in nature reserves.

**引言** 入侵物种可对包括自然保护区在内的诸多区域造成生态与经济损失。然而，自然保护区内水生入侵脊椎动物的入侵风险仍不明朗——这类生物常隐匿于水下，且在基于传统方法的生态调查中常被忽略。
**研究方法** 环境DNA（eDNA）为水生生态系统的生物多样性调查提供了极具前景的替代方案。本研究从中国广东省的8个自然保护区采集了水生环境DNA样本，旨在重点探究水生入侵脊椎动物的多样性，并评估其在这些保护区内的入侵风险。
**结果与讨论** 本研究共检测到104种水生脊椎动物，隶属于3纲（辐鳍鱼纲Actinopteri、两栖纲Amphibia、爬行纲Reptilia）、12目、32科及71属，其中9种为入侵物种（占所有检测到的水生脊椎动物的8.65%），分别为：齐氏非鲫（Coptodon zillii）、伽利略罗非鱼（Sarotherodon galilaeus）、尼罗罗非鱼（Oreochromis niloticus）、坦噶尼喀罗非鱼（Oreochromis tanganicae）、食蚊鱼（Gambusia affinis）、斑胡子鲶（Clarias gariepinus）、鳄龟（Chelydra serpentina）、红耳滑龟（Trachemys scripta elegans）及美洲牛蛙（Rana catesbeiana）。
值得注意的是，55.56%的水生入侵脊椎动物（即5个物种）在至少75.00%的样本中被检出，其中齐氏非鲫与伽利略罗非鱼在所有样本（100%）中均有检出，表明多数入侵物种在这些自然保护区内分布广泛。此外，所有水生入侵脊椎动物物种的序列相对丰度均位居前列（在所检测的水生脊椎动物中排名前66位）；在序列数最多的前10个物种中，有3种为入侵物种（齐氏非鲫、伽利略罗非鱼及尼罗罗非鱼），提示这类入侵脊椎动物拥有较高的种群规模。
此外，本研究还检测到16种濒危/受威胁物种（占所有检测到的脊椎动物的15.38%），其地理分布与入侵物种存在显著重叠。上述入侵物种高丰度、广分布且与濒危/受威胁物种分布重叠的现状，表明广东省自然保护区内的水生入侵脊椎动物面临着可观的入侵风险，亟需开展有效的防控管理。本研究可为制定有效的管理措施以降低入侵物种造成的损失、推动自然保护区内濒危/受威胁物种的保护工作提供基础理论参考。