The aim of present research is to study the patterns of phyto- and zooplankton fluctuations in endorheic soda lakes (Uldz Gol-Torey Basin, southeastern Transbaikalia, Russia) under arid conditions because studied area is becoming increasingly arid. Plankton samples were collected in summer during time intervals with different lake water levels using standard hydrobiological methods. We detected four patterns of change in plankton communities with changing environmental conditions (increasing total dissolved solid, pH and temperature, and decreasing depth). The first pattern is characterized by a predominance of green algae, charophytes, diatoms and euglenophytes; the species composition and dominant zooplankton assemblage are the same in different years. The second pattern is characterized by a loss of cryptophyte and chrysophyte algae, a dominance of green and blue-green algae, a decrease in zooplankton species diversity, and an increased abundance of zooplankton, the dominant species are consistent over time. The third pattern exhibits marked decreases in phytoplankton diversity and density, a dominance of green algae and diatoms, a further decrease in the species richness of zooplankton, and increased abundance and biomass of some species. The fourth pattern is a marked by a reduction in plankton species diversity to a monospecific community.

中文翻译：

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外贝加尔（俄罗斯）东南部内陆苏打湖浮游生物群落结构的波动

本研究的目的是研究干旱条件下内陆苏打湖（Uldz Gol-Torey 盆地，俄罗斯外贝加尔东南部）中植物和浮游动物的波动模式，因为研究区域变得越来越干旱。浮游生物样本是在夏季使用标准水生生物方法在不同湖水位的时间间隔内收集的。我们检测到浮游生物群落随着环境条件的变化（溶解固体总量增加、pH 值和温度增加以及深度减少）的四种变化模式。第一种模式的特点是绿藻、轮藻、硅藻和裸藻占优势；不同年份的物种组成和优势浮游动物组合相同。第二种模式的特征是隐生植物和金藻类藻类的丢失，绿藻和蓝绿藻占主导地位，浮游动物物种多样性减少，浮游动物丰度增加，优势物种随着时间的推移是一致的。第三种模式表现为浮游植物多样性和密度显着下降，绿藻和硅藻占优势，浮游动物物种丰富度进一步下降，部分物种的丰度和生物量增加。第四种模式的标志是浮游生物物种多样性减少到单一群落。浮游动物物种丰富度进一步下降，某些物种的丰度和生物量增加。第四种模式的标志是浮游生物物种多样性减少到单一群落。浮游动物物种丰富度进一步下降，某些物种的丰度和生物量增加。第四种模式的标志是浮游生物物种多样性减少到单一群落。