摘要：The seasonal and spatial eukaryotic phytoplankton composition in the Fenhe River was investigated based on the 18S rDNA V4 region. The relationship between phytoplankton functional groups and environmental factors was explored to effectively capture the responses of these taxa to environmental gradients and their effects on ecosystem function. Our results indicated that the Chlorophyta and Bacillariophyta had higher relative abundance than other taxa, and their diversity and richness indices in spring were higher than those in other seasons. The linear discriminant analysis effect size (LEfSe) analyses detected that the potential seasonal biomarkers included
Desmodesmus,
Cyclotella,
Pseudoschroederia,
Discostella,
Scenedesmus,
Monoraphidium, and
Nannochloropsis; the spatial biomarkers included
Amphora,
Neochloris,
Hindakia,
Pseudomuriella,
Coccomyxa,
Chloroidium,
Scherffelia,
Chromochloris, and
Scotinosphaera. The systemic evolution and distribution characteristics of the first 50 representative sequences showed that the dominant genus included
Desmodesmus in spring,
Pseudopediastrum in summer,
Mychonastes in autumn, and
Monoraphidium in winter. Main seasonal variation of phytoplankton functional groups was as follows: spring (J + F + C + X1) → summer (J + F + X1 + X2) → autumn (J + F + X1 + C) → winter (X1 + J + B + X2). Pearson correlation, redundancy analysis, and variance partitioning analysis showed temperature and phosphate were the determining factors causing the changes of phytoplankton functional groups and community composition in the Fenhe River.
