Characteristics of phytoplankton distribution for assessment of water quality in the Zhalong Wetland, China

Phytoplankton community structures of water environmental were monitored from July to August 2010 in Zhalong Wetland in northeast China. Phytoplankton community was obtained from samples taken from 341 stations with different environmental conditions. Physicochemical parameters (chemical oxygen demand, the total nitrogen, the total phosphorus, chlorophyll a (Chl-a)) were measured simultaneously for comparison with phytoplankton samples. A total of 410 phytoplankton taxa belonging to 7 phyla, 9 classes, 20 orders, 29 families, 79 genera were obtained. The mean value of trophic state index (TSI) was 49.87 and ranged from 34.89 to 69.12. The dominant species in the study area included Anabaena azotica, Selenastrum minutum, Chlorella vulgaris, Trachelomonas volvocina, Navicula radiosa, and indicator species suggesting that most of the Zhalong Wetland is mesotrophic. The TSI, phytoplankton density, Shannon–Wiener index, Margalef index also indicated that the water quality was a mesotrophic state in Zhalong Wetland.