The African sharptooth catfish, Clarias gariepinus, contributes much to the River Nile ecosystem by its high omnivorosity, sturdiness, growth rates, and fecundity. It was globally appreciated as a key fluvial aquaculture species. Yet, it is also one of the top world freshwater aliens. Monitoring the genetic diversity of different economically and ecologically important species as well as development of markers that aid their tracing and abundance are fundamental. This is chiefly due to the growing international threats of environmental pollution, reduction, and loss of biodiversity. Herein, the genetic diversity of C. gariepinus along the River Nile in Egypt was assessed through sequencing of the mitochondrial cytochrome oxidase subunit I (COI). Also, a qPCR assay based on C. gariepinus 16srDNA was developed to assess the species abundance through environmental water DNA samples (eDNA). The results showed low genetic diversity of that species in Egypt. Moreover, its populations exhibited high rates of fixation. Testing its eDNA-based marker resulted in an unambiguous quantitative trend in situ, in agreement with reports of local fishermen. These eDNA signals were strong at least 1 Km upstream to the initial sampling areas, even where no C. gariepinus fishing activities are carried out. This possibly indicated a degree of homogenous species-abundance in each of the studied areas. Finally, the results identified a need for better conservation strategies for C. gariepinus, since its low diversity in the Egyptian River Nile may represent a threat against its persistence under the continuously changing environmental conditions. Moreover, using non-invasive sampling methods, e.g. based on aquatic eDNA quantification, can aid much the detection of areas of abundance of C. gariepinus, especially for both the economic importance it contributes and the invasive power it possesses.

中文翻译：

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基于DNA和eDNA的北非锐齿cat鱼Clarias gariepinus跟踪。

非洲锐齿cat鱼Clarias gariepinus的全食性，坚固性，增长率和繁殖力对尼罗河生态系统做出了很大贡献。它被公认为重要的河流水产养殖物种。然而，它也是世界上最重要的淡水外星人之一。监测不同的具有重要经济和生态意义的物种的遗传多样性以及开发有助于其追踪和丰富度的标记物是至关重要的。这主要是由于国际环境污染，减少和生物多样性丧失的威胁日益严重。在此，通过对线粒体细胞色素氧化酶亚基I（COI）进行测序，评估了埃及尼罗河沿岸的加里皮梭菌的遗传多样性。此外，基于C的qPCR分析。开发了gariepinus 16srDNA以通过环境水DNA样品（eDNA）评估物种的丰度。结果表明埃及该物种的遗传多样性低。此外，其种群显示出高固定率。测试其基于eDNA的标记后，与当地渔民的报告一致，在原位产生了明确的定量趋势。这些eDNA信号在初始采样区域上游至少1 km处很强，即使没有进行钩端螺旋藻捕捞活动也是如此。这可能表明在每个研究区域中均一的物种丰富度。最后，研究结果确定了需要对C. gariepinus采取更好的保护策略，由于其在埃及尼罗河中的低多样性可能会威胁到其在持续变化的环境条件下的持久性。而且，使用非侵入性采样方法，例如基于水生eDNA定量，可以极大地帮助检测gar.piniepinus的丰富区域，尤其是从其贡献的经济重要性及其拥有的侵入能力两方面。