Spatiotemporal distribution of size-fractioned phytoplankton in the Yalu River Estuary, China

ABSTRACT The grain size structure of phytoplankton has great influence on shellfish culture. The present study aimed to assess the spatial and temporal variation in the phytoplankton community structure in the Yalu River Estuary and to explore the relationship between the phytoplankton community structure and various environmental parameters in 2020. High-throughput sequencing was used in this study. The results showed that nanophytoplankton, especially Karlodinium veneficum, dominated the estuary throughout the year. The biomass ratio of picophytoplankton, nanophytoplankton, and microphytoplankton were 20:63:17 in spring, 30:44:26 in summer, 1:38:61 in autumn, and 2:45:53 in winter, respectively. Meanwhile, Dinophyta had the greatest biomass throughout the year, followed by Bacillariophyta. On the spatial dimension (Station average), COD, T, SST had a positive impact on total phytoplankton communities, and Dep had a negative impact. In the time dimension (Monthly average), the environmental factor that significantly controlled the phytoplankton community structure were NO2 and SST.