1. Pressures on coastal ecosystems are increasing and aquatic species that are restricted to these habitats are facing the threat of extinction. However, the true extent of many threatened and rare aquatic species, especially elasmobranchs, remains unclear due to high levels of data deficiency and poor efficacy of traditional survey methods. Sawfishes (Pristidae), a family of shark-like rays, are among the most threatened and rare elasmobranch species and are difficult to detect in turbid, coastal habitats. Reliable cost-effective tools to detect these species are urgently needed to increase their conservation potential.
2. Characterization of environmental DNA (eDNA) extracted from water samples has garnered significant appeal for detection of rare and threatened species. To assist conservation and monitoring efforts for sawfishes using eDNA, species-specific TaqMan quantitative polymerase chain reaction assays were developed and validated to detect 1.25–5 copies of a 12S rRNA gene fragment. Filter samples were collected in Northern Territory, Australia to assess the utility of the developed eDNA assays and compare the efficacy of preservation and extraction workflows for detecting rare species.
3. Dwarf sawfish (Pristis clavata) were detected in three of 20 sites, and there was a significant effect of preservation and extraction workflow on total eDNA yield and subsequent detection success. Longmire's preserved samples extracted using glycogen-aided precipitation yielded a significantly higher concentration of total eDNA (n = 60; β = 1.27, t(95) = 8.172, P < 0.0001) and yielded positive P. clavata eDNA detections compared to ethanol preserved samples extracted using QIAGEN DNeasy kit, which did not yield any positive detections.
4. The optimized eDNA assays were developed to support monitoring efforts for endangered sawfishes. Importantly, this study demonstrates that choice of preservation and extraction workflow requires careful consideration, especially when detection of rare or threatened species can have important management and conservation outcomes.

中文翻译：

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使用最佳 eDNA 保存和提取工作流程提高检测灵敏度及其在受威胁锯鳐中的应用

1. 沿海生态系统的压力越来越大，仅限于这些栖息地的水生物种正面临灭绝的威胁。然而，由于数据严重缺乏和传统调查方法效率低下，许多受威胁和稀有水生物种的真实范围仍不清楚，尤其是板鳃类动物。锯鳐（Pristidae）是一种类似鲨鱼的鳐鱼，是最受威胁和最稀有的弹鳃类物种之一，在混浊的沿海栖息地很难被发现。迫切需要可靠的经济有效的工具来检测这些物种，以增加它们的保护潜力。
2. 从水样中提取的环境 DNA (eDNA) 的表征对于稀有和受威胁物种的检测具有重要意义。为了使用 eDNA 协助锯鳐的保护和监测工作，开发并验证了特定物种的 TaqMan 定量聚合酶链反应检测，以检测12S rRNA 基因片段的1.25-5 个拷贝。在澳大利亚北领地收集过滤样品，以评估开发的 eDNA 检测的效用，并比较保存和提取工作流程在检测稀有物种方面的功效。
3. 在 20 个地点中的三个地点检测到矮锯鳐（Pristis clavata），保存和提取工作流程对 eDNA 总产量和后续检测成功率有显着影响。与乙醇保存的样品相比，使用糖原辅助沉淀提取的 Longmire 保存的样品产生了显着更高浓度的总 eDNA（n  = 60；β  = 1.27，t (95) = 8.172，P  < 0.0001）并且产生了阳性P. clavata eDNA 检测使用 QIAGEN DNeasy 试剂盒提取，未产生任何阳性检测结果。
4. 开发优化的 eDNA 检测是为了支持对濒危锯鳐的监测工作。重要的是，这项研究表明，保护和提取工作流程的选择需要仔细考虑，尤其是当发现稀有或受威胁的物种可以产生重要的管理和保护结果时。