Study On Phytoplankton Community Structure And Its Indication Of Environment Of Lake Taiping In Anhui

Lake Taiping is located in Huangshan District of Anhui Province.lt is one of thelargest reservoir type lakes in Anhui province. It has been listed as the second batch ofnational ecological environment protection projects in2012，and one of the nationalkey protection lakes in2015. Its ecological environment protection has become apirority in the future. At present?its ecological baseline information is lacking，and theenvironmental research reports based on phytoplankton indicators are also rare. Apreliminary study was conducted on the phytoplankton community structure in LakeTaiping from September2012to March2013once every two months. Pearsoncorrelation analysis was used to study the correlation between phytoplankton andenvironmental factors，and a preliminary ecological assessment was conducted by thephysicochemical and biological indexes of phytoplankton. At the same time’ there wasa comparison with previous studies to provide basic data and resources of waterecological environment protection in Lake Taiping.1. A total of7phyla,96genera and131species were identified (includ speciesand varieties). The phytoplankton community was dominated by Chlorophyta, whichwas comprised of42genera and73species, accounted for55.7%of the total species.Secondly, Bacillariophyta (24genera and25species) and Cyanophyla (16genera and17species) accounted for19.1%and13.0%respectively.The average phytoplankton density and biomass were134.77x104cells/L andl.Olmg/L respectivelyt dominated by Cyanophyta，Bacillariophyta and Chlorophyta.The dominant species were Microcystis， Oscillatoira, Anabaena，Aphanizomenon flos-aquae， Pseudanabaena mucicola, Chroomonas acuta，Cryptomonas erosa，Synedra, Fragilaria，Melosira，Cyclotella，Crucigenia tetrapediaand Chlorella, belonging to13species in4phyla. 2,Theseasonal order of phytoplankton species number from high to low wasautumni winter, summer，spring, and the spatial order was upstream, midstream anddownstream.The phytoplankton density was134,77x104cells/L averagely in a year. Itranged from high to low in the following season order: autumn, summer, spring andwinter, and the spatial order was HI，H3，H2，H4and H5. The phytoplankton biomasswas].01mg/L averagely in a year. Its seasonal variation was the same tophytoplankton density, and the spatial order was HI? H3，H4, H5and H2. Besides,vertical distribution decreased from upper layer to sublayer.The dominant species ranged from high to low in the following season order:summer，spring, autumn, winter. On the vertical distribution，there were somedifferences between different sampling stations on dominant species.The seasonal order of Shannon-weaver index from high to low was autumn，spring，winter, summer and the Margelaf index was autumn, winter, spring andsummer. Meanwhile，the Pielou index was in order of autumn, spring, summer andwinter.In space，Shannon-weaver index and Margelaf index of H1and H4were higherthan those in the other sampling stations, while the Pielou index was no significantdifferent between different sampling stations. On the vertical distribution，threediversity indexes decreased from upper layer to sublayer.3.Duringthe investigationi water quality evaluation results based on the use ofphysical and chemical indicators of Lake Taiping showed that water qualityconditions were good with I? II type water in the four seasons. Water qualityconditions were mesotrophic，(3-mesosaprobic and light to moderate pollution basedon the biomass? dominant species and diversity indexes respectively. The results ofdifferent evaluations were almost consistent, indicating the water environment qualitywas light to moderate pollution.Compared with the previous results，there was no big change in composition ofphytoplankton species. Cyanophyta was still a majority，but large volumephytoplankton had increased significantly, Xanthophyta and chlorophyta volvoxwhich were indicators of clean water had disappeared? while more than50%added phytoplankton were indicative species of mesosaprobic zone，suggesting the currentwater quality state had declined，but not to the degree of deterioration.4.The SPSS sotfware was used to analysis the correlation and monadic linearregression between phytoplankton and environment factors. The results were asfollows: the main factors that impacted the distribution and variation of phytoplanktonin Lake Taiping were water temperature，transparency, dissolved oxygen and totalnitrogen. However, pH，CODMntn. toal phosphorus, ammonia nitrogeand BOD5hadno significant correlation with phytoplankton indexes.