Copepods are important contributors to the zooplankton community in lakes. Being “sandwiched” between predators and resources, they are sensitive to changes in the environment. It has been proposed that the proportion of calanoids of total copepod abundance or biomass could be a valuable indicator of eutrophication. We investigated relationships between environmental factors and the abundance, biomass and size of calanoid and cyclopoid copepods as well as their proportions in summer in 68 Danish freshwater lakes (587 lake years) with contrasting nutrient levels and pH. When lake pH was < 6.0, mean lake depth and trophic state were the most important factors and calanoids completely dominated the copepod community. In shallow lakes with a mean depth < 2.5 m and with pH > 6.0, the proportion of calanoids in terms of biomass decreased substantially with increasing phosphorus and chlorophyll a concentrations but stayed around 50% at > 2.5 m depth irrespective of nutrient level. Time series of the lakes, recovering from eutrophication, confirmed this multi-lake pattern although the trajectory varied from lake to lake. We conclude that the proportion of calanoids in terms of biomass might be a valuable indicator of trophic state in shallow but not deep lakes and only when pH > 6.

桡足类是湖泊浮游动物群落的重要贡献者。它们夹在捕食者和资源之间，对环境的变化很敏感。有人提出，桡足类总丰度或生物量的海藻素比例可能是富营养化的一个有价值的指标。我们调查了环境因素与 68 个丹麦淡水湖（587 个湖年）中的海藻类和环足类桡足类的丰度、生物量和大小之间的关系，以及它们在夏季具有对比营养水平和 pH 值的比例之间的关系。当湖泊 pH < 6.0 时，平均湖深和营养状态是最重要的因素，而海藻类完全支配了桡足类群落。在平均深度 < 2.5 m 且 pH > 6.0 的浅湖中，就生物量而言，随着磷和叶绿素 a 浓度的增加，类胡萝卜素的比例显着降低，但在 > 2.5 m 深度处，无论营养水平如何，都保持在 50% 左右。从富营养化中恢复的湖泊的时间序列证实了这种多湖模式，尽管轨迹因湖泊而异。我们得出结论，就生物量而言，海藻素的比例可能是浅湖而非深湖中营养状态的重要指标，并且仅当 pH > 6 时。