千岛湖浮游植物群落结构的垂向分布特征及其影响因素

深水湖库浮游植物群落结构具典型垂向分异特征，是其水质和生态系统功能的考量要素之一；但对深水湖库浮游植物垂向分异的季节变化规律及其成因仍认识不清.以深水湖库千岛湖为例，通过春、秋两季全湖12个点位浮游植物群落结构及同步水质指标剖面变化的调查，揭示了典型深水湖库浮游植物群落结构的垂向分布特征及影响因素.结果表明，春季浮游植物丰度和叶绿素a最大值出现在次表层(2～5 m),而秋季浮游植物丰度和叶绿素a则在表层达到最大值，然后均随水深增加而下降.千岛湖浮游植物优势种属在垂向上呈现明显的分层特征，具体而言，春季表层和次表层主要以隐藻和假鱼腥藻为主，中层隐藻占据优势，而底层小环藻细胞丰度明显高于其他藻属；秋季表层优势属为假鱼腥藻和束丝藻，在次表层和中层，细鞘丝藻和假鱼腥藻占据优势地位，底层细鞘丝藻成为唯一优势属.此外，水体关键环境指标也存在明显的垂向变化，春季水体氮和磷营养盐浓度与水深呈负相关，而秋季则呈相反趋势；统计分析表明春季浮游植物丰度垂向分布与磷酸盐浓度显著正相关，秋季浮游植物丰度垂向分布则与光照强度呈现显著正相关，而水温、硝态氮和总氮则是驱动两季浮游植物优势属垂向分布的主要因素.综上所述...

Vertical Distribution Characteristics and Influencing Factors of Phytoplankton Community Structure in Qiandao Lake

Clear vertical variations in phytoplankton community structure are usually observed in deep-water lakes and reservoirs, which is one of the key components of water quality and ecosystem functioning. However, the vertical patterns and ecological drivers of phytoplankton communities in deep-water lakes and reservoirs are still understudied. In this study, we took Qiandao Lake, a deep-water reservoir, as an example to reveal the vertical distribution characteristics of phytoplankton communities and its influencing factors by investigating phytoplankton community structure and the associated water quality index at 12 sites across the whole lake in two seasons (spring and autumn). The results showed that the phytoplankton abundance and chlorophyll a were highest in the surface layer in autumn and then decreased toward deep water, whereas in spring, the maximum value occurred in the subsurface layer (2-5 m), and the dominant phytoplankton species showed obvious vertical stratification characteristics. Specifically, in spring, Cryptomonas and Pseudanabaena dominated the surface and subsurface layers, Cryptomonas dominated in the middle layer, and the abundance of Cyclotella at the bottom layer was significantly higher than that of the other algae genera. The dominant genera in autumn were Pseudanabaena and Aphanizomenon. In the subsurface and middle layers, Leptolyngbya and Pseudanabaena occupied the dominant position, and Leptolyngbya became the only dominant genus. In the bottom layer, Leptolyngbya was the only dominant genus. The key environmental indicators of the water also had obvious vertical changes. The contents of N and P nutrients had a negative correlation with the water depth in spring, whereas the reverse trend was observed in autumn. The correlation analysis showed that the vertical variation in phytoplankton abundance in spring was significantly positively correlated with phosphate concentration, whereas the vertical distribution of phytoplankton abundance in autumn was significantly positively correlated with intensity of light, and the water temperature, NH₄⁺-N, and total nitrogen were the main factors driving the vertical changes in the dominant genera of phytoplankton community in the two seasons. To summarize, environmental conditions such as water temperature, light, and nutrients had strong effects on the vertical distribution of phytoplankton. In the ecological investigation and quality assessment of deep-water lakes and reservoirs, the vertical distribution characteristics of the phytoplankton community structure and the influence of environmental conditions should be fully considered.