Phytoplankton Composition And Variation In The ShuangLong Lake

ShuangLong lake is located in the northern part of ChongQing, YuBei district, which has rich water resource and is a satellite city. As a lake in urban city, ShuangLong lake improve the city'scenery, provide people a comfort area for entertainment. But because of incautious development, ShuangLong lake was polluted seriously, and decrease the limited rain Gathering area gradually. YuBei district have a synthetically treatment engineering on the lake: Establish the sewage system along the shore to collect the waste water; Arrange plant decontamination bed to make the rainwater clean; Whole cure the lake gulf and plant the shore to protect the water body; Pure the lake's bottom, implement dredging engineering; Arrange deep water aerate and circulation equipments which can make the water flow; Put the fish fry into the lake to protect water body.This research analysis begin after synthesizing treatment, There are 6 sampling sites in ShuangLong lake, from Jul.2005 to Jun.2006, determined physical-chemical indexes such as water temperature, PH, total nitrogen, total phosphorus every mouth. appraised phytoplankton species complexity; numerated phytoplankton cell density; analyzed various kinds of biological diversities, and making ecological evaluation of water quality. The result demonstrated that:①Total nitrogen of ShuangLong lake ranged 1.212～2.105mg/L, and total phosphorus ranged 0.037～0.125mg/L in one year. Using the software of SPSS 11.5 to analyse the relationship of the phytoplankton abundance ,water temperature, PH, total nitrogen and total phosphorus. Educing the phytoplankton abundance, total nitrogen and total phosphorus have remarkable interrelated relationship; TN/TP exceed 15, total phosphorus maybe the restrictive factor in ShuangLong lake. ShuangLong lake's water quality satisfy water standard ofⅣ.②8 phyla, 66 genera and 122 species (including varieties) of phytoplankton community in the waters of the ShuangLong lake were identified. The phytoplankton abundance of each sampling station ranged: 410.8~562.8×104cells/L. Chlorophyta and Cyanophyta were dominating in most mouth of one year. Cyanophyta, Cryptophyta and Pyrrophyta were increased largely in spring. Especially, the P. bipes Stein. growth very fast on Mar. and Apr., resulting in the water body presented red and brown, water quality get worse. With the rainy season's coming in summer, Chlorophyta is preponderant obviously. The species and quantity of Bacillariophyta get increase in autumn. In general, the phytoplankton of ShuangLong lake represent the variation with years in different condition of hydrology and climate.③Analyzing the index of biologic diversity of phytoplankton, index of Shsannon-Wiener,index of Margale and index of Pilou all show that water quality of ShuangLong lake was mid- contaminated. Moreover; overall evaluation of the phytoplankton showed that, ShuangLong lake water body has been in the rich nutritional level. Water quality is best in summer and worst in spring.