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.