Anthropogenic and natural climate-impacted water level (WL) fluctuations are one of many environmental problems affecting natural ecosystems. The aim of this study was to explain differences in the development of autotrophic and heterotrophic plankton in two shallow, temperate, embanked lakes with different modes of WL regulation. Lake Mytycze has natural WL changes supplied exclusively by precipitation; a decrease in water level was predominantly due to more evaporation than precipitation. In this lake, nutrient concentration, particulate matter, growth of toxigenic cyanobacteria and contamination with microcystins correlated positively with decreases in WL. Lake Tomaszne has anthropogenic WL regulation, elevated values of nutrients and particulate matter, but they were caused by the periodic, abrupt entrance of river waters rich in allochthonous nutrients, organic and inorganic particles. In this lake, a higher biomass of cyanobacteria was observed than in the lake with natural WL changes; the concentrations of intracellular microcystins in water correlated positively with the biomass of toxigenic species. In both lakes, decreases in the biomass of algivorous crustaceans correlated with the occurrence of cyanobacterial biomass. Biomasses of algivorous crustaceans increased abruptly when concentration of microcystins diminished below 2 μg∙dm⁻³. These biomass peaks occurred due to rapid development of the cladocerans; Bosmina longirostris was found in the lake with natural WL changes and Daphnia cucullata was found in the lake with anthropogenic WL regulation. The development of predacious crustaceans was not related to the blooms of filamentous cyanobacteria or the biomass of algivorous crustaceans (as potential prey). In both lakes, Thermocyclops crassus and Mesocyclops leuckartii (Copepoda) contributed significantly to the biomass of predacious crustaceans; their abundance correlated positively with the amount of particulate matter, which was probably utilised as an alternative food source. These findings illustrate indirect influence of WL on plankton composition and biomass through alteration of environmental variables. The results indicate that the mode of WL regulation (natural vs anthropogenic) must be taken into consideration when estimating the influence of WL changes on plankton dynamics.

人为和自然气候影响的水位（WL）波动是影响自然生态系统的许多环境问题之一。这项研究的目的是解释在两个不同温升调节模式的浅温带堤岸湖泊中自养和异养浮游生物的发育差异。Mytycze湖的自然WL变化完全由降水提供；水位下降的主要原因是蒸发量多于降水量。在该湖中，养分浓度，颗粒物，产毒蓝藻的生长以及微囊藻毒素的污染与WL的降低呈正相关。Tomaszne湖具有人为的WL调节，营养物质和颗粒物的值升高，但它们是由周期性的，富含异源营养素，有机和无机颗粒的河水突然进入。在该湖中，观察到的蓝藻生物量高于自然WL变化的湖。水中细胞内微囊藻毒素的浓度与产毒物质的生物量呈正相关。在这两个湖泊中，藻类甲壳类动物的生物量减少与蓝细菌生物量的发生有关。当微囊藻毒素的浓度降低到2μg∙dm以下时，藻类甲壳类动物的生物量突然增加。藻类甲壳类动物的生物量减少与蓝细菌生物量的发生有关。当微囊藻毒素的浓度降低到2μg∙dm以下时，藻类甲壳类动物的生物量突然增加。藻类甲壳类动物的生物量减少与蓝细菌生物量的发生有关。当微囊藻毒素的浓度降低到2μg∙dm以下时，藻类甲壳类动物的生物量突然增加。⁻³。这些生物量峰值是由于锁骨的迅速发展而产生的。在湖中发现了具有自然WL变化的Bosmina longirostris，并且在人为WL调控的湖中发现了Daphnia cucullata。捕食甲壳类动物的发育与丝状蓝藻的繁殖或藻类甲壳动物的生物量（作为潜在的猎物）无关。在这两个湖泊，Thermocyclops克拉苏和中剑leuckartii（Copepoda）显着促进了早熟甲壳类动物的生物量；它们的丰度与颗粒物的量成正相关，颗粒物的量可能被用作替代食物来源。这些发现说明了WL通过改变环境变量对浮游生物组成和生物量的间接影响。结果表明，在估算WL变化对浮游生物动力学的影响时，必须考虑WL调节模式（自然与人为）。