Itakura Hikaru, Wakiya Ryoshiro, Sakata Masayuki K, Hsu Hsiang-Yi, Chen Shih-Chong, Yang Chih-Chao, Huang Yi-Cheng, Han Yu-San, Yamamoto Satoshi, Minamoto Toshifumi
Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, 146 Williams St., Solomons, MD 20688, USA.
Graduate School of Science, Kobe University, 1-1 Rokkoudaichou, Nadaku, Kobe, Hyogo 657-8501, Japan.
Zool Stud. 2020 Jun 9;59:e17. doi: 10.6620/ZS.2020.59-17. eCollection 2020.
Although populations of anguillid eels have declined remarkably in recent decades, monitoring data on the spatial and temporal variation in their dynamics are often limited, particularly for tropical eel species. As there are often sympatries of multiple eel species in tropical rivers, identifying eel species based solely on morphological characteristics is challenging. Basin-scale surveys were conducted in rivers of southern Japan and northern Taiwan to investigate (1) whether the spatial distribution, abundance, and biomass of the tropical eel species, the giant mottled eel (), can be monitored in rivers by comparing the results obtained from environmental DNA (eDNA) analysis with data from electrofishing and (2) the riverine distribution of the sympatric and the temperate eel species, the Japanese eel (), in this region using eDNA analysis. Although we found an much lower abundance of in the study region, we identified the eDNA of the species from all of the study sites (21 sites) where it was collected by electrofishing, in addition to 22 further study sites where it was not collected directly. This indicates that eDNA analysis has a greater sensitivity for detecting , making it a powerful tool for monitoring the spatial distribution of the species in rivers. We found a significant positive relationship between eDNA concentration and both the abundance and biomass of , and eDNA concentration seemed to better reflect the abundance of the species than did biomass. eDNA of both and was identified from almost all rivers, indicating the sympatry of these species in this region, although the degree of sympatry differed between rivers. Though the eDNA concentration of decreased significantly with increasing distance from the river mouth, no significant relationship was found for . This study is the first to demonstrate the potential usefulness of eDNA analysis for estimating the spatial distribution, abundance, and biomass of tropical eels in rivers and to further apply this method to investigate sympatry among anguillid species. eDNA analysis can help in obtaining data on the population dynamics of tropical eels, providing invaluable information for managing these species.
尽管近几十年来鳗鲡种群数量显著下降，但关于其动态时空变化的监测数据往往有限，尤其是对于热带鳗鲡物种。由于热带河流中通常存在多种鳗鲡物种的同域分布，仅根据形态特征来识别鳗鲡物种具有挑战性。我们在日本南部和台湾北部的河流中进行了流域尺度的调查，以研究：（1）通过将环境DNA（eDNA）分析结果与电捕鱼数据进行比较，是否能够在河流中监测热带鳗鲡物种——巨斑花鳗（）的空间分布、丰度和生物量；（2）利用eDNA分析该地区同域分布的 以及温带鳗鲡物种——日本鳗鲡（）的河流分布情况。尽管我们发现在研究区域内 的丰度低得多，但除了22个未直接采集到该物种的其他研究地点外，我们在通过电捕鱼采集到该物种的所有研究地点（21个地点）都鉴定出了其eDNA。这表明eDNA分析在检测 方面具有更高的灵敏度，使其成为监测该物种在河流中空间分布的有力工具。我们发现eDNA浓度与 的丰度和生物量之间均存在显著的正相关关系，而且eDNA浓度似乎比生物量能更好地反映该物种的丰度。几乎在所有河流中都鉴定出了 和 的eDNA，这表明这些物种在该地区同域分布，尽管不同河流中的同域程度有所不同。虽然 的eDNA浓度随着离河口距离的增加而显著降低，但对于 未发现显著关系。本研究首次证明了eDNA分析在估计河流中热带鳗鲡的空间分布、丰度和生物量方面的潜在实用性，并进一步应用该方法来研究鳗鲡物种之间的同域分布情况。eDNA分析有助于获取热带鳗鲡种群动态数据，为管理这些物种提供宝贵信息。
