Aquatic invertebrates are excellent indicators of ecosystem quality; however, choosing a sampling method can be difficult. Each method and associated protocol has advantages and disadvantages, and finding the approach that minimizes biases yet fulfills management objectives is crucial. To test the effects of both sampling methods and sample handling—i.e., to composite samples or leave them as replicates—we collected aquatic invertebrates from the Niobrara River at Agate Fossil Beds National Monument, Nebraska, using three methods and two sample handling protocols. We compared aquatic invertebrate assemblages collected with a Hester-Dendy multi-plate sampler, Hess sampler, and a D-frame dipnet. We calculated six common bioassessment metrics from composite (combined) and replicate (separate) samples. Hess samples contained the highest taxonomic richness (capturing 77% of all taxa observed) and dipnet samples the least (47%). Hester-Dendy samples had the greatest proportion of Ephemeroptera, and Ephemeroptera, Plecoptera, and Trichoptera (EPT). Dipnet samples had the lowest evenness values. In terms of sample handling, composite samples had inflated richness, diversity, and evenness compared with replicate samples, but bioassessment metrics calculated from proportions or averages (i.e., Hilsenhoff’s Biotic Index and the proportion of EPT taxa) did not differ between them. The proportion of invertebrate groups from composite samples were not statistically different among sampling methods, but several groups differed between replicate samples collected by different methods. Ultimately, we recommend collecting replicate samples with a Hess sampler when the goal of the study is to detect ecosystem change, among locations or differences in variables of interest.

中文翻译：

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合成或复制：采样方法和协议差异如何改变采集的流无脊椎动物和相关的生物评估指标。

水生无脊椎动物是生态系统质量的良好指标；但是，选择采样方法可能很困难。每种方法和相关的协议都有优点和缺点，因此找到使偏差最小化但又能实现管理目标的方法至关重要。为了测试采样方法和样品处理的效果（即合成样品还是将其作为重复样品），我们使用三种方法和两种样品处理方案从内布拉斯加州玛瑙化石床国家纪念碑的尼布拉拉河收集了水生无脊椎动物。我们比较了使用Hester-Dendy多板采样器，Hess采样器和D框架网罩收集的水生无脊椎动物组合。我们从复合样本（合并样本）和重复样本（分离样本）中计算了六个常见的生物评估指标。Hess样本包含最高的分类学丰富度（捕获到的所有分类单元占77％），而Dipnet样本最少（47％）。Hester-Dendy样品的星状目，星状目，鞘翅目和毛翅目（EPT）所占比例最大。Dipnet样本的最低均匀度值。在样品处理方面，与重复样品相比，复合样品的丰富度，多样性和均匀性均得到了提高，但是根据比例或平均值（即，希尔森霍夫的生物指数和EPT分类单元的比例）计算出的生物评估指标之间没有差异。复合样品中无脊椎动物组的比例在抽样方法之间没有统计学差异，但是在不同方法收集的重复样品之间，有几个组存在差异。最终，