Phytoplankton Community and the Relationship with the Environment in Nansi Lake, China

This study was carried out from June to October 2008 in Nansi Lake. Based on the data collected from five sampling stations, phytoplankton taxonomic composition, abundance, temporal variations and spatial distribution were examined. About 94 species, including 48 species of Chlorophyta, 22 species of Bacillariophyta, and 1 water bloom causative species were identified. Average phytoplankton diversity index and evenness values were 1.59 and 0.58, respectively, revealing moderate biodiversity of phytoplankton biocoenosis. The phytoplankton abundance averaged 1.52×107 cells/L, and was much higher than previous investigation carried out in the same months in 1995. The species of Chlorophyta, Bacillariophyta dominated phytoplankton community. The main dominant species were Scenedesmus dimorphus, Chlorella vulgaris, Synedra acus, Aulacoseira granulata, Merismopedia tenuissima and Monallantus brevicylindrus. Concerning nutrient stoichiometry, it was suggested that the higher TN: TP ratio indicated potential P-limitation for phytoplankton growth in Nansi Lake. The environmental conditions of water quality and phytoplankton community composition indicated that Nansi Lake was eutrophic in summer.