1. Information on α- (local), β- (between habitats), and γ- (regional) diversity is fundamental to understanding biodiversity as well as the function and stability of community dynamics. Methods like environmental DNA (eDNA) metabarcoding are currently considered useful to investigate biodiversity.
2. We compared the performance of eDNA metabarcoding with visual and capture surveys for estimating α- and γ-diversity of river fish communities, and nestedness and turnover in particular.
3. In five rivers across west Japan, by comparison to visual/capture surveys, eDNA metabarcoding detected more species in the study sites (i.e. α-diversity). Consequently, the overall number of species in the region (i.e. γ-diversity) was higher. In particular, the species found by visual/capture surveys were encompassed by those detected by eDNA metabarcoding.
4. Estimates of community diversity within rivers differed between survey methods. Although we found that the methods show similar levels of community nestedness and turnover within the rivers, visual/capture surveys showed more distinct community differences from upstream to downstream. Our results suggest that eDNA metabarcoding may be a suitable method for community assemblage analysis, especially for understanding regional community patterns, for fish monitoring in rivers.

中文翻译：

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与河流鱼类群落的视觉和捕获调查相比，通过环境 DNA 元条形码估计生物多样性指标

1. 有关 α-（本地）、β-（栖息地之间）和 γ-（区域）多样性的信息对于了解生物多样性以及群落动态的功能和稳定性至关重要。目前认为环境 DNA (eDNA) 元条形码等方法可用于研究生物多样性。
2. 我们将 eDNA 元条形码的性能与视觉和捕获调查进行了比较，以估计河鱼群落的 α 和 γ 多样性，尤其是嵌套和周转。
3. 在日本西部的五条河流中，与视觉/捕获调查相比，eDNA 元条形码在研究地点检测到更多物种（即α-多样性）。因此，该地区的物种总数（即γ-多样性）较高。特别是，通过视觉/捕获调查发现的物种包含在通过 eDNA 元条形码检测到的物种中。
4. 河流内群落多样性的估计因调查方法而异。虽然我们发现这些方法在河流内显示出相似的群落嵌套和周转水平，但视觉/捕获调查显示从上游到下游的更明显的群落差异。我们的结果表明，eDNA 元条形码可能是一种合适的群落组合分析方法，特别是对于了解区域群落模式，以及河流鱼类监测。