Abstract The presence of chironomids and/or oligochaetes is generally considered to be an indication of poor status of freshwater. Non-chironomid dipterans show unclear trends. The abundance and percentage of these groups are rarely used as potential indicators. We attempted to determine whether these metrics reveal freshwater quality in lowland streams and lake littoral (Northern Europe, Baltic ecoregion, Estonia). The water quality was assessed based either on the water itself or on macroinvertebrates, fish, macrophytes, phytobenthos (in streams only) and/or phytoplankton (in lakes only). As expected, the high abundance and high percentage of chironomids and ceratopogonids indicated low quality of water in lakes. The high percentage of chironomids indicated low water quality also in streams. The high percentage of oligochaetes indicated low water quality in lakes. However, their high abundance (but not the percentage) was unexpectedly a symptom of high water quality in streams and to a lesser extent in lakes. In these cases, oligochaetes were represented by rheophilic, rather than saprophilic species. The abundance of simuliids (but not the percentage) and the richness of dipteran families indicated high water quality in streams. We suggest that the obtained results will allow better use of the indicative potential of freshwater macroinvertebrates.

中文翻译：

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双翅目幼虫和寡毛纲的丰度和百分比是否表明溪流和湖泊沿岸水质低？

摘要 摇蚊和/或寡毛纲动物的存在通常被认为表明淡水状况不佳。非摇蚊双翅目显示出不明确的趋势。这些群体的丰度和百分比很少用作潜在指标。我们试图确定这些指标是否揭示了低地溪流和湖泊沿岸（北欧、波罗的海生态区、爱沙尼亚）的淡水质量。水质评估基于水本身或大型无脊椎动物、鱼类、大型植物、底栖植物（仅在溪流中）和/或浮游植物（仅在湖泊中）。正如预期的那样，摇蚊科动物和角马科动物的高丰度和高百分比表明湖泊中的水质量低。摇蚊的高百分比表明溪流中的水质也很低。高比例的寡毛纲动物表明湖泊水质较差。然而，它们的高丰度（但不是百分比）出乎意料地是溪流水质高的征兆，在较小程度上是湖泊水质的征兆。在这些情况下，寡毛纲动物以亲流变物种而不是亲腐物种为代表。simuliids 的丰度（但不是百分比）和双翅目家族的丰富度表明溪流中的水质很高。我们建议获得的结果将允许更好地利用淡水大型无脊椎动物的指示潜力。simuliids 的丰度（但不是百分比）和双翅目家族的丰富度表明溪流中的水质很高。我们建议获得的结果将允许更好地利用淡水大型无脊椎动物的指示潜力。simuliids 的丰度（但不是百分比）和双翅目家族的丰富度表明溪流中的水质很高。我们建议获得的结果将允许更好地利用淡水大型无脊椎动物的指示潜力。