Investigation and analysis of the status of plankton in Xiangjiang river

The status of plankton in Xiangjiang river was investigated in different seasons from April 2009 to November 2010.The results showed that there were 127 species of phytoplankton,belonging to 8 phyla including 44 species of Chlorophyta,38 species of Bacillariophyta,13 species of Cyanophyta,9 species of Euglenophyta,7 species of Cryptophyta,6 species of Xanthophyta,and 5 species of Pyrrophyta and Chrysophyta respectively;the average density of phytoplankton was 2.91×104 ind/L,and the biomass was 0.15 mg/L;the biomass of the Bacillariophyta was the largest,accounting for 41.8% of the total biomass,and the predominant species were Melosira granulate,Synedra acus and Navicula radiosa.There were 91 species of zooplankton,among which 38 species belonged to Rotifera,19 species belonged to Copepoda,18 species belonged to Protozoa and 16 species belonged to Cladocera;the average density of zooplankton was 13.94 ind/L,and the biomass was 0.24 mg/L;the biomass of the Cladocera was the largest,accounting for 47.7% of the total biomass;Cyclops and Calanus were the predominant species appearing all over the year.The plankton in Xiangjiang river belonged to the typical river-type community structure in terms of species composition,which explained that the Xiangjiang river was in poor to moderate nutritional status.