Freshwater picocyanobacteria (Pcy) are important yet understudied components of lake ecosystems. Most previous studies have relied on cell abundances to assess Pcy dynamics in largely oligotrophic lakes, while little is known about spatial diversity and dynamics across different lake types. In the present study we assessed the horizontal-spatial abundance and community structure of Pcy in two contrasting (oligotrophic and hypertrophic) New Zealand lakes using epifluorescence microscopy and 16S rRNA metabarcoding. Pcy abundance and community composition differed significantly both between and within the oligotrophic and hypertrophic lakes. While spatial variability was observed in both study lakes, these differences were particularly pronounced in the oligotrophic, morphometrically complex Lake Wanaka where cell abundances were typically higher in bays than open-water sites and community structure differed significantly between sites. Community structuring appeared to be driven by localised environmental conditions, with different factors influencing each lake. These results suggest that single spot-samples are insufficient to gain an understanding of Pcy dynamics and consequently, phytoplankton dynamics in lakes.

中文翻译：

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使用环境 DNA 元条形码揭示两个对比湖泊中微微蓝细菌群落的空间丰度和分布

淡水微微蓝细菌（Pcy）是湖泊生态系统的重要组成部分，但尚未得到充分研究。先前的大多数研究都依赖于细胞丰度来评估主要寡营养湖泊中的 Pcy 动态，而对不同湖泊类型的空间多样性和动态知之甚少。在本研究中，我们使用落射荧光显微镜和 16S rRNA 宏条形码评估了两个对比鲜明（贫营养和肥营养）的新西兰湖泊中 Pcy 的水平空间丰度和群落结构。贫营养型和富营养型湖泊之间和内部的 Pcy 丰度和群落组成存在显着差异。虽然在两个研究湖泊中都观察到了空间变异性，但这些差异在寡营养、形态复杂的瓦纳卡湖中尤其明显，其中海湾中的细胞丰度通常高于开放水域，并且不同地点之间的群落结构存在显着差异。群落结构似乎是由当地环境条件驱动的，每个湖泊都有不同的影响因素。这些结果表明，单点样本不足以了解 Pcy 动态，进而了解湖泊中浮游植物的动态。