Dataset of the phytoplankton (including the biomass of potentially invasive cyanobacterium Sphaerospermopsis aphanizomenoides), physical and chemical parameters, and basic morphological and hydrological data of 49 lakes located at latitudes 51-55◦N

This dataset shows data collected for the purpose of the study of Budzyńska et al. 2019 “Environmental factors driving the occurrence of the invasive cyanobacterium Sphaerospermopsis aphanizomenoides (Nostocales) in temperate lakes”, Science of the Total Environment 650: 1338-1347. The aim of this study was to identify physical, chemical and biological factors related to the occurrence of the potentially invasive cyanobacterium Sphaerospermopsis aphanizomenoides (Nostocales, Cyanobacteria; synonyms: Aphanizomenon aphanizomenoides, Anabaena aphanizomenoides). We hypothesized that S. aphanizomenoides would live in the warmest and most nutrient-rich lakes, thus co-occurring with dense cyanobacterial blooms. Forty-nine freshwater lakes located between latitudes 51º and 55ºN (mid-eastern and north-eastern parts of Poland, temperate zone) were examined for the presence of S. aphanizomenoides. The location was chosen due to its proximity to the putative current northern limits of the range of the species. Environmental factors that could drive the occurrence of S. aphanizomenoides were studied simultaneously. The study was conducted in summer 2015, in the warmest period of the year. The samples were taken in the pelagic zone of each lake using a hosepipe sampler (Mantzouki et al., accepted in Scientific Data). Each lake was sampled once. An integrated sample form throughout the epilimnion and metalimnion was collected to avoid overlooking the presence of S. aphanizomenoides. As potential drivers of the occurrence of the species, the following parameters were analysed: water temperature, conductivity, total phosphorus concentration (TP), total nitrogen concentration (TN), the ratio of euphotic zone depth to the depth of water mixing, total phytoplankton biomass as a measure of lake productivity, and also lake area and the maximum lake depth. To identify environmental factors related to the occurrence of S. aphanizomenoides, principal component analysis (PCA) was performed with the use of Canoco for Windows 5.0 software. The same environmental factors were compared between two groups of lakes (lakes with a record of S. aphanizomenoides versus lakes without a record) using the Mann-Whitney U test in Statistica 12.5 software. We found that water temperature did not differentiate lakes with or without S. aphanizomenoides, but total phosphorus concentration was the primary driving factor of the occurrence of S. aphanizomenoides. The cyanobacterium lived mainly in lakes with high phytoplankton biomass and low underwater light penetration. In this dataset we included the following data: ▪ characteristic of the studied lakes (location, basic data on hydrology and morphometry); ▪ sampling data; ▪ phytoplankton data (biomass of S. aphanizomenoides, its share in total phytoplankton biomass, the total biomass of phytoplankton and the biomass of Cyanoprokaryota); ▪ data on potential environmental drivers of the occurrence of S. aphanizomenoides.本数据集对应Budzyńska等2019年发表于《Science of the Total Environment》（总环境科学）的研究论文《温带湖泊中入侵性蓝藻Sphaerospermopsis aphanizomenoides（念珠藻目）的发生驱动环境因子》（第650卷：1338-1347页）。本研究旨在明确与潜在入侵性蓝藻Sphaerospermopsis aphanizomenoides（念珠藻目，蓝藻门；异名：Aphanizomenon aphanizomenoides、Anabaena aphanizomenoides）发生相关的物理、化学及生物因子。研究假设S. aphanizomenoides会栖息于水温最高、营养盐最丰富的湖泊中，因此会与高密度蓝藻水华伴生。 研究共调查了位于北纬51°至55°之间（波兰中东部与东北部温带区域）的49座淡水湖泊，以检测S. aphanizomenoides的存在。该采样区域的选取依据是其接近该物种当前推测的分布北限。本研究同时探究了可能驱动S. aphanizomenoides发生的环境因子。研究于2015年夏季，即一年中气温最高的时段开展。采用软管采样器（Mantzouki等，收录于《Scientific Data》）于各湖泊的远洋带（pelagic zone）采集样本。每个湖泊仅采样一次。我们采集了温跃层上层（epilimnion）与斜温层（metalimnion）的整合水样，以避免遗漏S. aphanizomenoides的存在。 作为该物种发生的潜在驱动因子，我们分析了以下参数：水温、电导率、总磷浓度（TP）、总氮浓度（TN）、真光层深度与水体混合深度之比、表征湖泊生产力的浮游植物总生物量，以及湖泊面积与最大湖深。为明确与S. aphanizomenoides发生相关的环境因子，我们使用Windows版Canoco 5.0软件开展了主成分分析（PCA，principal component analysis）。我们借助Statistica 12.5软件中的曼-惠特尼U检验（Mann-Whitney U test），对比了存在S. aphanizomenoides记录的湖泊与无该物种记录的湖泊两组间的环境因子差异。 研究结果表明，水温并未对有无S. aphanizomenoides的湖泊产生显著区分效果，而总磷浓度是驱动S. aphanizomenoides发生的首要因子。该蓝藻主要栖息于浮游植物生物量较高、水下光穿透能力较弱的湖泊中。 本数据集包含以下数据： ▪ 研究湖泊的特征信息（地理位置、水文及形态测量学基础数据）； ▪ 采样相关数据； ▪ 浮游植物数据（S. aphanizomenoides的生物量、其在浮游植物总生物量中的占比、浮游植物总生物量及蓝原核生物（Cyanoprokaryota）生物量）； ▪ S. aphanizomenoides发生的潜在环境驱动因子相关数据。