The ecological state of aquatic ecosystems is systematically monitored using various bioindicators in many countries worldwide. In the European Union, freshwater biomonitoring is the central component of the EU Water Framework Directive (WFD, 2000/60/EC) and currently based on morpho-taxonomic methods. DNA metabarcoding is a novel approach to assess the ecological state fast and efficiently based on organismal DNA signatures and thereby support and upscale biomonitoring. However, compliance of metabarcoding with existing morpho-taxonomic methods must be ensured prior to official implementation. Thus, this study co-designed by research institutions and environmental agencies explored necessary key parameters and performed method intercalibration for the implementation of metabarcoding into WFD assessments of running waters. We focussed on benthic invertebrates as the most commonly used bioindicators. We analysed 170 invertebrate samples collected as part of the German federal state WFD routine stream biomonitoring, first via microscopic determination and then using metabarcoding. Our goals were to quantify overlap in i) taxonomic composition and ii) ecological status derived with both methods. For this purpose, we established data harmonisation measures to integrate invertebrate metabarcoding data into the official national WFD classification modules considering abundance and presence/absence data. Our results revealed a high (ca. 70%) overlap of bioindicator taxa found with both methods. Metabarcoding identified significantly more small invertebrate taxa and detected similar proportions of the important bioindicator ‘EPT’ taxa (mayflies, stoneflies, caddisflies). Despite deviations in some detected bioindicator taxa, the derived ecological status classes were highly correlated between methods, particularly after intercalibration (R²=0.74, Spearman rho=0.86). Regardless of whether we used abundance or presence/absence data, the resulting stream type classifications showed strong agreement. Thus, our study not only demonstrates the consistency of the methods for the stream types analysed but is also the first to operationalise a path to integration of metabarcoding data into the WFD assessment modules based on formal intercalibration guidelines.

中文翻译：

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适合目的？根据《水框架指令》评估底栖无脊椎动物 DNA 宏条形码，用于溪流生态状况等级评估


全球许多国家使用各种生物指标系统地监测水生生态系统的生态状况。在欧盟，淡水生物监测是欧盟水框架指令 （WFD， 2000/60/EC） 的核心组成部分，目前基于形态分类学方法。DNA 宏条形码是一种基于生物体 DNA 特征快速有效地评估生态状态的新方法，从而支持和扩大生物监测规模。然而，在正式实施之前，必须确保元条形码符合现有的形态分类学方法。因此，本研究由研究机构和环境机构共同设计，探索了必要的关键参数，并进行了方法互校准，以将元条形码实施到流水的 WFD 评估中。我们专注于底栖无脊椎动物作为最常用的生物指标。我们分析了作为德国联邦州 WFD 常规溪流生物监测的一部分收集的 170 个无脊椎动物样本，首先通过显微镜测定，然后使用元条形码。我们的目标是量化 i） 分类组成和 ii） 两种方法得出的生态状况的重叠。为此，我们建立了数据协调措施，将无脊椎动物元条形码数据整合到官方国家 WFD 分类模块中，同时考虑丰度和存在/不存在数据。我们的结果显示，两种方法都发现了生物指示剂类群的高重叠 （约 70%）。元条形码识别了明显更多的小型无脊椎动物分类群，并检测到了相似比例的重要生物指标“EPT”分类群（蜉蝣、石蝇、水蛾）。 尽管一些检测到的生物指示剂分类群存在偏差，但得出的生态状况类别在方法之间高度相关，尤其是在相互校准后 （R²=0.74，Spearman rho=0.86）。无论我们使用的是丰度还是存在/不存在数据，生成的流类型分类都显示出很强的一致性。因此，我们的研究不仅证明了所分析的流类型方法的一致性，而且还首次根据正式的相互校准指南将元条形码数据集成到 WFD 评估模块中。