Abstract: Maotiao River is a typical karst river, whose downstream reservoir is an important source of drinking water in Guiyang. To explore the variations of the composition of phytoplankton functional groups and its correlation with environmental factors in the Maotiao River Basin, phytoplankton were sampled and river physicochemical parameters were analyzed in June, August and November 2020, based on redundancy analysis and correlation analysis methods. During the investigation period, 7 phyla and 67 species (genera) of phytoplankton were recorded in the Maotiao River Basin, with the most species from Chlorophyta. The phytoplankton community structure varied temporally and spatially. The phytoplankton cell abundance across sampling sections ranged 0.11×10⁶-17.71×10⁶ cells·L^-1, and biomass ranged 29.85-1256.16 μg·L^-1. The phytoplankton in the Maotiao River Basin could be divided into 24 functional groups, with B, MP, S1, Y, and D were the dominant functional groups. The biomass of functional group D peaked at 1256.85 μg·L^-1 in August. The dominant functional groups were adapted to turbid meso-eutrophic water bodies. The phytoplankton functional groups showed significant temporal succession. The results of redundancy analysis showed that water temperature, pH, and electrical conductivity were the main environmental factors affecting the variations of phytoplankton functional groups in the Maotiao River Basin.

Key words: phytoplankton functional group, redundancy analysis, environmental factor, Maotiao River Basin.