1. Environmental DNA (eDNA) monitoring is a useful tool for species detection but its use in addressing management questions remains scarce. One factor limiting the use of eDNA as a routine monitoring tool is uncertainty around the potential of eDNA data to estimate species abundance. While several confounding factors limit the ability of eDNA data to estimate absolute abundances at large spatial and temporal scales, eDNA data have the potential to estimate relative species abundances patterns at smaller scales, and this information can assist management.
2. Environmental DNA and conventional monitoring surveys were conducted in the Abercrombie River catchment (Australia) where an incursion of the invasive redfin perch (Perca fluviatulis) threatens the survival of a population of endangered Macquarie perch (Macquaria australasica). Species-specific assays were used to quantify eDNA concentrations from water samples and estimate the relative abundance of both species. Electrofishing and fyke netting surveys were used to validate key observations from the eDNA survey.
3. Environmental DNA of both species was detected at all sites except one, where redfin perch DNA was not detected. Between species comparisons of eDNA concentrations revealed a clear negative relationship between the eDNA concentrations of both species, consistent with other evidence of redfin perch having a negative impact on Macquarie perch populations. Between site comparisons of redfin perch eDNA concentrations showed evidence of a novel incursion of the species in the upper reaches of the Abercrombie River and conventional monitoring in the following year confirmed the pattern of increased redfin perch abundances from downstream to upstream sites.
4. Relative comparisons of eDNA concentrations of aquatic species can be used to assess species interactions and reveal unexpected species abundance patterns (e.g. allowing inferences of novel incursions of invasive species). This information is critical to evaluate current, and design future, management strategies. Consequently, while deriving absolute species abundances from quantitative eDNA data may remain challenging, the use of quantitative eDNA surveys can provide relative abundance patterns valuable to the conservation and management of invasive and endangered species.
5. The quantitative nature of eDNA survey data has been debated extensively in the current literature because of potential confounding influences. Current study results show that these confounding influences may be less problematic at small spatial scales and quantitative eDNA data can be effective to monitor relative species abundances patterns.

中文翻译：

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定量环境 DNA 分析对入侵和濒危本地鱼类管理的价值

1. 环境 DNA (eDNA) 监测是一种有用的物种检测工具，但它在解决管理问题方面的应用仍然很少。限制使用 eDNA 作为常规监测工具的一个因素是 eDNA 数据估计物种丰度的潜力的不确定性。虽然有几个混杂因素限制了 eDNA 数据在大空间和时间尺度上估计绝对丰度的能力，但 eDNA 数据有可能在较小尺度上估计相对物种丰度模式，而这些信息可以帮助管理。
2. 在阿伯克龙比河集水区（澳大利亚）进行了环境 DNA 和常规监测调查，在那里入侵的红鳍鲈 ( Perca fluviatulis)的入侵威胁到濒临灭绝的麦夸里鲈鱼 ( Macquaria australasica)种群的生存。物种特异性测定用于量化水样中的 eDNA 浓度并估计两种物种的相对丰度。使用电捕鱼和 fyke 网调查来验证 eDNA 调查的关键观察结果。
3. 除了一个没有检测到红鳍鲈鱼 DNA 的地点外，所有地点都检测到了这两种物种的环境 DNA。物种间 eDNA 浓度的比较揭示了两个物种的 eDNA 浓度之间存在明显的负相关关系，这与红鳍鲈鱼对麦格理鲈鱼种群产生负面影响的其他证据一致。红鳍鲈鱼 eDNA 浓度的站点比较显示了该物种在阿伯克龙比河上游新入侵的证据，第二年的常规监测证实了从下游到上游站点的红鳍鲈鱼丰度增加的模式。
4. 水生物种 eDNA 浓度的相对比较可用于评估物种相互作用并揭示出乎意料的物种丰度模式（例如，允许推断入侵物种的新入侵）。这些信息对于评估当前和设计未来的管理策略至关重要。因此，虽然从定量 eDNA 数据推导出绝对物种丰度可能仍然具有挑战性，但使用定量 eDNA 调查可以提供对保护和管理入侵和濒危物种有价值的相对丰度模式。
5. 由于潜在的混杂影响，eDNA 调查数据的定量性质在当前文献中已被广泛讨论。目前的研究结果表明，这些混杂的影响在小空间尺度上可能不太成问题，定量 eDNA 数据可以有效地监测相对物种丰度模式。