The aim of this study was to determine factors affecting the vertical distribution of Eurytemora lacustris in mesotrophic lakes (Wigry, Hańcza, Szurpiły; north-eastern Poland) during the summer stagnation. Eurytemora lacustris was found in all of the studied lakes, with the highest abundance (8 ind. L-1) in Lake Wigry. In Lake Szurpiły, E. lacustris has never been recorded before. The results of this study revealed that E. lacustris was most numerous in thermocline zones, suggesting that this species could temporarily tolerate warmer water and lower oxygen concentrations due to better food resources. During the study, it was found that a large part of the E. lacustris population had epibiont ciliates, in contrast to other species of zooplankton that did not have any epibionts. The improvement in the water quality of many deep lakes could lead to an increase in the abundance of E. lacustris. However, epibiont ciliates may be a threat for this species and may play a substantial role in determining the production, distribution, and community dynamics of E. lacustris.

中文翻译：

---

层状中营养湖泊中的遗物Eurytemora lacustris（Copepoda，Calanoida）的垂直分布。

这项研究的目的是确定在夏季停滞期间影响中营养湖泊（维格里，汉茨扎，苏尔皮瓦伊；波兰东北部）的湖红藻垂直分布的因素。在所有研究过的湖泊中都发现了Eurytemora lacustris，在Wigry湖中的丰度最高（8 ind。L-1）。在祖尔皮维湖中，从未见过大肠埃希氏菌的记录。这项研究的结果表明，在温床地区，E。lacustris数量最多，这表明该物种可以暂时忍受较温暖的水和较低的氧气浓度，因为它们拥有更好的食物资源。在研究过程中，与其他没有表皮动物的浮游动物相比，发现大肠埃希菌的大部分具有表生动物纤毛。许多深湖水质的改善可能导致大肠埃希氏菌的丰度增加。然而，表生纤毛虫可能对该物种构成威胁，并可能在决定漆球菌的生产，分布和群落动态中起重要作用。