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.
Sci Rep. 2020 May 29;10(1):8790. doi: 10.1038/s41598-020-65883-4.
To monitor and manage biodiversity, surrogate species (i.e., indicator, umbrella and flagship species) have been proposed where conservation resources are focused on a limited number of focal organisms. Using data obtained from 78 sites across six rivers in the mainland Japan and the Amami-Oshima Island, we demonstrate that two anguillids - the Japanese eel (Anguilla japonica) and the giant mottled eel (A. marmorata) - can act as surrogate species for conservation of freshwater biodiversity. Anguillid eels were the widest topographically-distributed species ranging from near the mouth to the upper reaches of rivers. Moreover, stable isotopic analyses indicated that eels are likely one of the highest-order predators in freshwater ecosystems. A significant positive relationship was found between the density of eels and the number of other diadromous species collected. However, the optimal models revealed that both the density of eels and the number of other diadromous species were significantly negatively correlated with distance from the river mouth and cumulative height of trans-river structures from the river mouth to each site. This suggests the positive relationship between eel density and number of other diadromous species was indirect and related to river-ocean connectivity. Given their catadromous life-cycle, and global commercial and cultural importance, as a taxa, anguillid eels can act as indicator, umbrella and flagship species, and a comprehensive surrogate for conservation of freshwater biodiversity.
为了监测和管理生物多样性，人们提出了替代物种（即指示、伞护和旗舰物种）的概念，即将保护资源集中在有限数量的焦点生物上。本研究利用在日本本州和奄美大岛的 6 条河流的 78 个站点获得的数据，证明了两种鳗鲡 - 日本鳗鲡（Anguilla japonica）和巨石斑鱼（A. marmorata） - 可以作为保护淡水生物多样性的替代物种。鳗鲡是分布范围最广的物种，从河口到河流上游都有分布。此外，稳定同位素分析表明，鳗鱼可能是淡水生态系统中最高级的捕食者之一。鳗鱼密度与采集到的其他洄游物种数量之间存在显著的正相关关系。然而，最优模型显示，鳗鱼密度和其他洄游物种数量都与从河口到每个站点的河流高度的累积高度呈显著负相关。这表明鳗鱼密度与其他洄游物种数量之间的正相关关系是间接的，与河流-海洋连通性有关。鉴于它们的溯河洄游生命周期，以及全球商业和文化的重要性，作为一个分类单元，鳗鲡可以作为指示、伞护和旗舰物种，以及保护淡水生物多样性的综合替代物。
