Studies On Community Structures Of Plankton And Its Relationships With The Environmental Factors In Jinshan Lake And Its Adjacent Ponds, Zhenjing City

Jinshan Lake is a typical small plain lake of Yangtze River delta area in Zhenjing City. We investigated the plankton, physical and chemical factors in Jinshan Lake and its adjacent waters for 7 times from Des. 2004 to Nov. 2005. We set 10 sample sites, among which 5 ones were in Jinshan Lake and the other 5 ones were in the adjacent waters. A detailed research on the composition and the changing rule of community structure of the plankton was taken. 4 diversity indexes were used to analyze the diversity of phytoplankton. Hierarchical Cluster Analysis (HCA) and Principal Components Analysis (PCA) were used to analyze the distribution patterns of the plankton. Multiple regression and Canonical Correspondence Analysis (CCA) were used to analyze the correlation of plankton species with environment factors. The nutrition status of the water was also been evaluated. What we did could provide background data for the ecological restoration of the water and provide the foundation for studying the ecological system structure and energy flow in Jinshan Lake.1. 302 taxa of phytoplankton were identified, which belonged to 99 genera of 8 phyla and included 253 species, 45 variations, 4 forms. The year's average biomass was 2989.32 ×10~4 ind/1. The biomass and the number of species of Chlorophyta ranked the first. There were 13 dominant species which included Chroomonas acuta Uterm., Chlorella vulgaris Beij. and Merismopedia tenuissima Lemm. and so on. The amount of species was the most in winter and the fewest in spring, and the trend of each site was similar to the whole. The biomass of phytoplankton is the best in summer and the fewest in spring. The average concentration of the chlorophyll a of a year is 96.40mg/m~3 and the highest value was present in summer. We calculated 4 diversity indexes, and the result showed that the level of Jinshan Lake was a little lower than adjacent waters.10 sites were divided into 3 teams by analyzing phytoplankton community structure distribution patterns.2. 92 species and genera of zooplankton were identified, among which there were Rotifera 68 species and genera, Cladocera 22 species and genera and Copepoda only 2 species. The average biomass and weight of zooplankton were 76100.95 ind/l and 71.52mg/l, of which Rotifera had abosluted dominance, especially Brachionus sp. which offen appears in the trophic lakes. The seasonal changing trend of specific composition and the biomass of the zooplankton were similar to the phytoplankton, and the amount...