Occurrence of the smallest phototrophic microorganisms (photoautotrophic picoplankton, APP) in Lake Balaton was discovered in the early 1980s. This triggered a series of systematic studies on APP and resulted in the setting of a unique long-term picoplankton dataset. In this review, we intend to summarize the obtained results and to give a new insight on APP ecology and diversity in Lake Balaton. According to the results, APP dynamics depends on trophic state, temperature, nutrient, and light availability, as well as grazing pressure. APP abundance in Lake Balaton decreased to a low level (1–2 × 10⁵ cells mL⁻¹) as a consequence of decreasing nutrient supply (oligotrophication) during the past more than two decades, and followed a characteristic seasonal dynamics with higher abundance values from spring to autumn than in winter. Concomitantly, however, the APP contribution to both phytoplankton biomass and primary production increased (up to 70% and 40–50%, respectively) during oligotrophication. Regarding annual pattern, picocyanobacteria are dominant from spring to autumn, while in winter, picoeukaryotes are the most abundant, most likely due to the different light and temperature optima of these groups. Within picocyanobacteria, single cells and microcolonies were both observed with mid-summer dominance of the latter which correlated well with the density of cladocerans. Community-level chromatic adaptation (i.e., dominance of phycoerythrin- or phycocyanin-rich forms) of planktonic picocyanobacteria was also found as a function of underwater light quality. Sequence analysis studies of APP in Lake Balaton revealed that both picocyanobacteria and picoeukaryotes represent a diverse and dynamic community consisting several freshwater genotypes (picocyanobacteria: Synechococcus, Cyanobium; picoeukaryotes: Choricystis, Stichococcus, Mychonastes, Nannochloris, and Nannochloropsis).

1980年代初发现了巴拉顿湖中最小的光养微生物（photoautotrophic picoplankton，APP）的出现。这引发了一系列关于 APP 的系统研究，并导致建立了一个独特的长期微型浮游生物数据集。在这篇综述中，我们打算总结所获得的结果，并对巴拉顿湖的 APP 生态和多样性提供新的见解。根据结果​​，APP动态取决于营养状态、温度、养分和光照有效性，以及放牧压力。巴拉顿湖的 APP 丰度降至低水平（1-2 × 10 ^{5 个} 细胞 mL ^-1）作为过去二十多年营养供应减少（贫营养化）的结果，并遵循特征性的季节性动态，从春季到秋季的丰度值高于冬季。然而，与此同时，APP 对浮游植物生物量和初级生产的贡献在贫营养化期间增加（分别高达 70% 和 40-50%）。关于年度模式，从春季到秋季，微型蓝细菌占优势，而在冬季，微型核生物最丰富，这很可能是由于这些群体的不同光照和温度最佳值。在 picocyanobacteria 中，单细胞和微菌落都被观察到，后者在仲夏占优势，这与枝角类动物的密度密切相关。社区水平的色彩适应（即，浮游微微蓝细菌的藻红蛋白或富含藻蓝蛋白形式的优势也被发现是水下光质量的函数。巴拉顿湖 APP 的序列分析研究表明，微型蓝藻和微型核生物都代表了一个由几种淡水基因型组成的多样化和动态群落（微型蓝藻：聚球藻，蓝藻；微小核生物：绒毛球菌属、Stichococcus属、Mychonastes、Nannochloris和Nannochloropsis）。