Abstract: From the viewpoints of species composition and biomass (size-fractionated chlorophyll a), an investigation was conducted on the phytoplankton composition at Zhangzhou section of Western Jiulong River during wet, normal, and dry seasons in 2010, with the relationships between the phytoplankton composition and environmental factors analyzed and the water quality assessed. In the study area, the proportion of picoplankton biomass to the total phytoplankton biomass had significant positive correlation with water temperature (P<0.05), and the proportion of microphytoplankton biomass to the total biomass had negative correlation with water total nitrogen (P<0.05). A total of 59 species belonging to 7 phyla were identified. The phytoplankton species composition and abundance varied with seasons and sites. In wet season, the proportion of Cyanobacteria increased (P<0.05), while that of Dinoflagellates decreased (P<0.05), as compared with those in dry season. Canonical correspondence analysis showed that water temperature and nutrients contents were the main environmental factors affecting the phytoplankton community composition and biomass at the Zhangzhou section of western Jiulong River.  

Key words: Astragalus membranaceus var. mongholicus, chemical composition, inorganic element, climatic factor.