Natural History Museum, University of Oslo, Oslo, Norway.
Group for Integrated Biological Investigation, Center for Advanced Studies of Biodiversity, Federal University of Pará, Belém, Brazil.
Sci Rep. 2024 Sep 3;14(1):20427. doi: 10.1038/s41598-024-71398-z.
Freshwater ecosystems are crucial for global biodiversity through supporting plant and animal species and providing essential resources. These ecosystems are under significant threat, particularly in island environments such as Madagascar. Our study focuses on the Amboaboa River basin, home to the rare and endemic fish species Rheocles derhami, last recorded in 2013. To assess the status of this and other threatened fish species including Ptychochromis insolitus and Paretroplus gymnopreopercularis, and to understand freshwater fish population dynamics in this biodiversity hotspot, we conducted a comprehensive survey using both environmental DNA (eDNA) and traditional fishing methods. While traditional methods effectively captured a diverse range of species, including several invasive aliens and the critically endangered endemic species that were the focus of this study, the eDNA approach detected only a fraction of these introduced species and struggled to identify some critically endangered endemics at the species level. This highlights the value of combining methods to enhance species detection. We also investigated the trade-offs associated with multi-primer assessments in eDNA analysis, focusing on three different primer combinations targeting the 12S mitochondrial gene: MiFish, Tele02, and Riaz. Additionally, we provided 12S reference barcodes for 10 species across 9 genera of fishes from the region to increase the coverage of the public reference databases. Overall, our study elucidates the current state of freshwater biodiversity in the Amboaboa River basin and underscores the value of employing multiple methods for effective conservation strategies.
淡水生态系统通过支持动植物物种和提供必要的资源，对全球生物多样性至关重要。这些生态系统受到了严重的威胁，尤其是在马达加斯加等岛屿环境中。我们的研究集中在 Amboaboa 河流域，这里是珍稀的特有鱼类 Rheocles derhami 的家园，该物种最后一次记录是在 2013 年。为了评估这一物种以及其他受威胁鱼类物种（包括 Ptychochromis insolitus 和 Paretroplus gymnopreopercularis）的状况，并了解这个生物多样性热点地区淡水鱼类种群的动态，我们使用环境 DNA（eDNA）和传统捕鱼方法进行了全面调查。虽然传统方法有效地捕获了包括几种入侵外来物种和我们研究重点的极度濒危特有物种在内的各种不同物种，但 eDNA 方法仅检测到这些引入物种的一小部分，并且难以在物种水平上识别一些极度濒危的特有物种。这突出了结合方法以增强物种检测的价值。我们还研究了 eDNA 分析中多引物评估相关的权衡取舍问题，重点关注了针对 12S 线粒体基因的三种不同引物组合：MiFish、Tele02 和 Riaz。此外，我们还为该地区 9 个属的 10 种鱼类提供了 12S 参考条形码，以增加公共参考数据库的覆盖范围。总的来说，我们的研究阐明了 Amboaboa 河流域淡水生物多样性的现状，并强调了采用多种方法进行有效保护策略的价值。
