Rivers play a crucial role in collecting and transporting microplastics. Nonetheless, the degree to which microplastic pollution of freshwaters affects its biota remains understudied. Sampling of wild fishes has so far demonstrated that microplastic ingestion occurs commonly across species with alternate feeding modes, as well as in different environmental compartments. Due to the exploratory nature of many preceding studies, drawing insight about factors driving microplastic ingestion has remained difficult. It continues unknown for instance, what the importance of varying environmental microplastic concentrations is to predict ingestion rates in fish from those areas. Here we show that ingestion rates of microplastic particles (>300 μm) in the benthic round goby from the Rhine river were negligible (1 particle in 417 fish). Among the 535 visually selected putative microplastic fragments, stringent data processing steps to reduce the number of false positives during reference library searches, revealed the importance of taking such steps into account in comparison with other data processing routines. Our observations remained consistent, despite having collected fish from a strongly polluted site of the lower Rhine, which served as contrast to a significantly cleaner site upstream. These results demonstrate that higher environmental microplastic concentrations are not necessarily mirrored by higher ingestion rates in a given fish species.

河流在收集和运输微塑料中起着至关重要的作用。尽管如此，淡水的微生物污染影响其生物群的程度仍未得到研究。迄今为止，对野生鱼类的取样表明，在具有不同喂养方式的物种中以及在不同的环境区隔中，通常会发生微量吸收。由于许多先前研究的探索性质，对驱动微塑料摄入的因素进行深入了解仍然很困难。例如，仍然未知的是，改变环境中塑料的浓度对于预测这些地区鱼类的摄食率有多重要。在这里，我们显示来自莱茵河底栖圆形虾虎鱼的微塑料颗粒（> 300μm）的摄入率可以忽略不计（417条鱼中有1个颗粒）。在535个从视觉上选择的推定的微塑料片段中，严格的数据处理步骤减少了参考库搜索过程中的假阳性数量，这表明与其他数据处理例程相比，考虑此类步骤的重要性。尽管我们从莱茵河下游污染严重的地方收集了鱼类，但与上游明显清洁的地方形成对比，我们的观察仍然一致。这些结果表明，给定鱼类的较高摄入速率不一定能反映出较高的环境微生物可塑性浓度。揭示了与其他数据处理例程相比，考虑此类步骤的重要性。尽管我们从莱茵河下游污染严重的地方收集了鱼类，但与上游明显清洁的地方形成对比，我们的观察仍然一致。这些结果表明，给定鱼类的较高摄入速率不一定能反映出较高的环境微生物可塑性浓度。揭示了与其他数据处理例程相比，考虑此类步骤的重要性。尽管我们从莱茵河下游污染严重的地方收集了鱼类，但与上游明显清洁的地方形成对比，我们的观察仍然一致。这些结果表明，给定鱼类的较高摄入速率不一定能反映出较高的环境微生物可塑性浓度。