| Water landscape is the core of Jiuzhaigou Nature Reserve, the water environment affects the sucesssion of the water ecosystem and aesthetic value of the landscape. As primary producers in aquatic environment, phytoplankton can reflect water quality and act an important role in water environment monitoring and protection. The study started from July 25 th to August 6th 2014, We surveyed structure of phytoplankton community and water quality in 12 main lakes and analyzed the change of the spatial distribution of phytoplankton in Long Lake and Five Colored Lake. The main results are listed as follows:69 genus of 7 Phylum including 138 species are identified in Jiuzhaigou Nature Reserve. Bacillariophyta has 42 genus 108 species, Chlorophycota has 15 genus 17 species, Cyanophyta has 5 genus 6 species and others 7 genus 7 species. Most species are tychoplankton-periphytic diatom, euplankton were composed of centricae and other algae.Different lakes have different structures of phytoplankton community. Except Cyclotella changhai and Ceratium hirundinella are dominant species in Long lake, Zechawa Valley. Tychoplankton-periphytic diatom are dominant species in most lakes of Shuzheng Valley and Rize Valley. Dominant species are similar in lakes of Shuzheng Valley, major dominant species are Achnanthidium minutissimum,Cyclotella changhai,Delicata delicatula,Denticula tenuis. While dominant species are differernt in lakes of Rize Valley. Dominant species of some lake are not even diatom, the major dominant species of Arrow Bamboo Lake is Gymnodinium sp., Peridinium sp. and Dinobryon divergens are dominant species of Panda Lake, Chlamydomonas sp. is occuring in Five Colored Lake as a dominant species.The study of spatial distribution of phytoplankton in Long Lake and Five Colored Lake showed as follow. In Long Lake, the phytoplankton distribution showed regular changes in both vertical and horizontal scale because of the structure of lake and no humen disturbance environment. The abundance(ind./L) of phytoplankton in Long Lake, effected by Cyclotella changhai, gradually increase along the direction of inlet to outlet. The abudance of phytoplankton in littoral area is higher than that in lake centre area. The abudance of phytoplankton showed a trend of decrease after the first increase in vertical scale. While, Ceratium hirundinella and Cyclotella changhai affecte the biomass(mg/L) of phytoplankton in Long Lake. The biomass of phytoplankton in middle area is higher than that in lake inlet and outlet. The biomass of phytoplankton in surface is the highest, then showed a trend of decrease after the first increase in vertical scale. In Five Colored Lake, the abundance(ind./L) of phytoplankton is the highest in platform area and diffuse to central area. That is mainly affected by tychoplankton-periphytic diatom and Chlamydomonas sp.Synthesizing all kinds of methods to evaluate water quality, We conclude that most lakes of Jiuzhaigou Nature Reserve are oligotrophic lakes, but platform area of Five Colored Lake is slight polluted. Utilizing structures of phytoplankton community to determine type of the lake. We find Panda Lake and Arrow Bamboo Lake are transforming macrophytic dominated lake to phytoplankton dominated lake. |
