Lakes in the Alps represent a considerable fraction of nutrient-poor lakes in Central Europe, with unique biodiversity and ecosystem properties. Although some individual lakes are well-studied, less knowledge is available on large-scale patterns essential to generalise the understanding of their functioning. Here, we aimed to describe crustacean zooplankton communities (Cladocera, Copepoda) and identify their environmental drivers in the pelagic zone of 54 oligotrophic lakes in the montane region of the Alps (400-1200 m) in Austria, Germany, and Switzerland, covering a spatial scale of 650 km. Moreover, we aimed to provide data on the distribution and ecological requirements of the North American invader Bytotrephes longimanus in its Central European native range. Communities were mainly dominated by widespread species typical of lowland habitats, and only a few true specialists of oligotrophic alpine lakes were present. The most frequent taxa were the Daphnia longispina complex and Eudiaptomus gracilis, with 48 and 45 occurrences, respectively. Species richness decreased with altitude and increased with lake area. The main structuring factors of community composition were chlorophyll a concentration and depth, which drove an apparent separation of mesotrophic and oligotrophic communities. Bytotrephes had 13 occurrences, showing a preference for deep oligotrophic lakes. Its presence was not coupled with lower crustacean species richness as it was repeatedly observed in North America. Additionally, it frequently co-occurred with the other large predatory cladoceran, Leptodora kindtii. B. longimanus might be considered a truly montane species in Central Europe, given its absence in lowland and alpine lakes.

中文翻译：

---

阿尔卑斯山北部山区湖泊中的浮游动物群落和 Bythotrephes longimanus。

阿尔卑斯山的湖泊占中欧营养贫乏湖泊的相当一部分，具有独特的生物多样性和生态系统特性。尽管对一些个别湖泊进行了充分研究，但对于概括理解其功能所必需的大尺度模式的知识却较少。在这里，我们旨在描述甲壳类浮游动物群落（枝角类、桡足类），并确定其在奥地利、德国和瑞士阿尔卑斯山山区（400-1200 米）的 54 个贫营养湖泊中上层区域的环境驱动因素，涵盖空间尺度650公里。此外，我们旨在提供北美入侵者 Bytotrephes longimanus 在其中欧本土范围内的分布和生态要求的数据。社区主要以低地栖息地典型的广泛分布的物种为主，只有少数真正的贫营养高山湖泊专家在场。最常见的分类群是 Daphnia longispina complex 和 Eudiaptomus gracilis，分别出现 48 次和 45 次。物种丰富度随海拔升高而降低，随湖泊面积而增加。群落组成的主要结构因素是叶绿素 a 浓度和深度，这推动了中营养和贫营养群落的明显分离。Bytotrephes 有 13 次出现，显示出对深贫营养湖泊的偏好。它的存在与在北美反复观察到的低级甲壳动物物种丰富度无关。此外，它经常与其他大型掠食性枝角类动物 Leptodora kindtii 共同发生。B. longimanus 可能被认为是中欧真正的山地物种，