Climate change has increased the frequency, duration and intensity of heatwaves in Europe. These extreme events result in alterations of physical, chemical, and biological properties of lakes that may synergistically promote cyanobacterial dominance. In our study we focused on cyanobacterial blooms in lakes distributed over a longitudinal gradient in Central Europe during one of the “top ten European heat waves” in summer 2015. 92 lakes were included in the study, located across three climatic subregions: cool northern lakes, situated in Lithuania, temperate northern lakes in Poland, and warm northern lakes in Croatia. The objective of the study was to determine if cyanobacterial biomass, predominant species, and cyanotoxin concentration differed, across the south-north gradient, as a function of water temperature, total phosphorus, and total nitrogen. Statistical significance of observed patterns was tested using the Kruskal-Wallis rank sum test and the generalized linear model. We found the lowest average epilimnion temperature, but the highest average cyanobacterial biomass in the northern, ‘cool’ lakes while the highest average temperature with the lowest average cyanobacterial biomass in the southern, ‘warm’ lakes. The concentration of cyanotoxins was also the highest in the ‘cool’ lakes. Total phosphorus and total nitrogen correlated significantly with cyanobacterial biomass, cyanotoxins concentration and biomass of some cyanobacterial species (mainly ), regardless of the latitude. Only in the ‘cool’ lakes concentration of cyanotoxins (microcystins and anatoxin-a) correlated significantly with cyanobacterial biomass and the biomass of some dominant cyanobacterial species (). Our results emphasized the differences of heat weaves impact on lakes of various latitudes, with the strongest increase in toxic cyanobacterial blooms in northern ‘cool’ lakes, situated in high latitudes. On the other hand, nutrients directly enhanced blooms across all the studied latitudes of Central Europe. The cyanobacteria species dominating in blooms might be recognized as ecological indicators of climate change, especially in the north-eastern part of Europe.

中文翻译：

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热浪期间中欧纵向梯度上的有害水华：蓝藻生物量、蓝藻毒素和营养物质

气候变化增加了欧洲热浪的频率、持续时间和强度。这些极端事件导致湖泊物理、化学和生物特性的改变，可能协同促进蓝藻的优势。在我们的研究中，我们重点关注 2015 年夏季“欧洲十大热浪”之一期间分布在中欧纵向梯度的湖泊中的蓝藻水华。研究涵盖了 92 个湖泊，分布在三个气候分区：凉爽的北部湖泊，位于立陶宛、波兰的温带北部湖泊和克罗地亚的温暖的北部湖泊。该研究的目的是确定南北梯度上蓝藻生物量、主要物种和蓝藻毒素浓度是否随水温、总磷和总氮变化而变化。使用 Kruskal-Wallis 秩和检验和广义线性模型测试观察到的模式的统计显着性。我们发现北部“冷”湖泊的平均水温最低，但平均蓝藻生物量最高，而南部“暖”湖泊的平均温度最高，平均蓝藻生物量最低。 “冷”湖中蓝藻毒素的浓度也是最高的。无论纬度如何，总磷和总氮与蓝藻生物量、蓝藻毒素浓度和某些蓝藻物种（主要是）的生物量显着相关。仅在“冷”湖中，蓝藻毒素（微囊藻毒素和赤霉素-a）的浓度与蓝藻生物量和一些优势蓝藻物种的生物量显着相关（）。我们的结果强调了热编织对不同纬度湖泊的影响的差异，其中位于高纬度的北部“冷”湖泊中有毒蓝藻水华的增长最为强劲。另一方面，营养物质直接促进了中欧所有研究纬度地区的开花。在水华中占主导地位的蓝藻物种可能被认为是气候变化的生态指标，特别是在欧洲东北部。