Phytoplankton Community Structures And Their Relationship With Nitrogen And Phosphorus In Huizhou West Lake

The eutrophication often leads to the growth of phytoplankton，resulting in waterquality deterioration. Community structure of phytoplankton in relation to nitrogenand phosphorus was investigated in6lake areas（Yuanmiaoguan、Nannanhu、Pinghu、Nanfenghu、Beifenghu、Beinanhu） of Huizhou West Lake，a shallow tropical lakefrom February2011to January2012. In order to research the control of nutrients tothe growth of phytoplankton. The results as follows:（1） According to the cell abundance，the dominant specie in Yuanmiaoguan andNannanhu was Chroomonas acuta throughout the year，except cyanobacteria speciesdominated in Nannanhu in summer. Merismopedia glauca and Limnothrix sp. werethe dominant species in Pinghu and Merismopedia glauca was the dominant specie ofBeifenghu and Beinanhu，while Merismopedia glauca and Chroomonas acuta werethe dominant species in Nanfenghu. According to the biomass，bacillariophyta，pyrroptata and cryptophyta species dominated in Yuanmiaoguan and Nannanhu，whilebacillariophyta and cryptophyta species were the dominant species in spring andwinter，cyanobacteria species were the dominant species in summer and autumn in theother lake regions.（2） Between six sampling sites，the difference of abundance of phytoplanktonwas Nannanhu <Yuanmiaoguan <Pinghu <Beifenghu <Nanfenghu <Beinanhu，thedifference of biomass of phytoplankton was Nannanhu <Yuanmiaoguan <Pinghu <Beifenghu <Beinanhu <Nanfenghu as well as chlorophyll a，the difference ofShannon-Weaver diversity index of phytoplankton was Nannanhu> Yuanmiaoguan>Nanfenghu> Pinghu> Beifenghu> Beinanhu.（3）In6lake areas， we tested TP、PO₄^3--P、TN、NO₃^--N、NO₂^—N and NH₄⁺-N，all of which in Nannanhu were lowest. The concentrations of TP、PO43--P、TN werehighest in Nanfenghu，the concentrations of NO₃^--N、NO₂^--N were highest inBeifenghu，the concentration of NH₄⁺-N was highest in Beinanhu. The value of N/Pwas Nannanhu> Yuanmiaoguan> Beifenghu> Beinanhu> Nanfenghu> Pinghu.（4） The regression analysis showed that the correlation between TN and biomass of phytoplankton was significant in summer and autumn，while the correlationbetween TP and biomass of phytoplankton was significant in spring. Correlationsbetween TN,TP and chlorophyll a were significant in the whole year，while thecorrelation between TN and Shannon-Weaver diversity index of phytoplankton wassignificant in autumn only.