Diversity And Community Characteristics Of Heterotriphic Flagellates In Baiyangdian Lake

Baiyangdian Lake, a shallow macrophytic lake, is the largest freshwater lake of North China Plain. In recent years, with the development of industry and agriculture, the environment of Baiyangdian Lake was severely damaged and the eutrophi cation of the lake became more and more serious. The species diversity and community characteristics of heterotrophic flagellates was studied, the results was as fllows:Heterotrophic flagellates were collected using PFU method and identified under the DIC microscope. Fifty species(including seven newly recorded species), assigned to33genus, were indentified in Baiyangdian Lake.The abundance and biomass of heterotrophic flagellates in surface water of Baiyangdian Lake were in the range of100-3200ind./ml and35.98-2328.85ug/L (annual average1054ind./ml and532.93μg/L), respectively. Heterotrophic flagellates smaller than7μm comprised47.11%of the total abundance and comprised6.82%of total biomass, and the Heterotrophic flagellates between7μm and14μm comprised37.42%of the total abundance and39.21%of the total biomass, while heterotrophic flagellates larger than14μm comprised15.47%of the abundance but contributed53.97%of the total biomass.Statistical analysis results showed that the abundance of heterotrophic flagellates had statistically significant negative correlation with total nitrogen (TN) and ammonia nitrogen, and had positive correlation with pH, bacterial abundance, ciliate abundance and chlorophyll a concentrations. The biomass of heterotrophic flagellates had statistically significant positive correlation with pH, dissolved oxygen (DO), ciliate abundance and chlorophyll a concentrations, and had negative correlation with total nitrogen (TN) and ammonia nitrogen. The results demonstrated that heterotrophic flagellates play a key role in the microbial food loop of Baiyangdian Lake.