Phytoplankton functional groups in Poyang Lake: succession and driving factors

Phytoplankton functional groups have gained increasing attention in recent years. To understand the composition of phytoplankton functional groups in Poyang Lake and their drivers, field investigations were conducted over three years: 2013, 2014, and 2016. Phytoplankton were dominated by diatoms, contributing from 20.19% to 57.57% of the total biomass, followed by cyanobacteria, 9.81%–39.98%. Microcystis sp. and Anabaena sp. were the dominant species among cyanobacteria. Twenty-six functional groups were identified among 72 genera or species, and fiver groups (P, B, MP, H1, and G) were categorized dominant. All of dominant groups except H1 were tolerate highly fluctuating mixing intensities and showed a typical monthly succession variation. Water temperature, water level, and nutrients are key drivers for the variation of phytoplankton communities at taxonomic and functional levels. Both of redundancy and variation partitioning analyses showed that environmental variables might explain functional groups better than taxonomic communities, implying that the functional groups were more advantageous in showing the effects of environmental conditions than taxonomic compositions. Hydrological conditions have a crucial influence on phytoplankton assemblage dynamics in highly variable water regime lakes, but not in the largest ones. The functional groups method is suitable for identifying the spatial and seasonal characteristics of aquatic environments that significantly affected by water regimes.