太湖水库蓄水前后浮游植物群落结构特征

Phytoplankton community structure characteristics before and after the impoundment in Taihu Reservoir

为了解太湖水库蓄水前和蓄水后浮游植物群落结构特征以及水质状况,分别于蓄水前(2014年6月)和蓄水后(2019年3月)进行水样采集,分析浮游植物群落结构特征和水质状况,并对浮游植物进行功能群划分。结果表明:①太湖水库蓄水前共检测出浮游植物1门21种,其中所有种类均属于硅藻门;蓄水后共检测出浮游植物4门25种。蓄水前呈现河流型特征,蓄水后呈现河流型和水库型双重特征。②太湖水库蓄水前共归类出5个功能类群,分别为D、LO、MP、P、X3;蓄水后共归类出8个功能类群,分别为D、J、LO、MP、P、T、X1、X3。浮游植物功能群演替明显:蓄水前MP+P+D→蓄水后P。③通过RDA分析得出,太湖水库蓄水前水温(WT)、溶解氧(DO)和化学需氧量(CODCr)是影响浮游植物分布的主要环境因子;蓄水后总氮(TN)、硝态氮(NO3--N)、悬浮物(SS)、透明度(SD)是主要环境因子。多样性指数和综合营养状态指数表明蓄水前和蓄水后太湖水库均处于中营养,水库建坝蓄水后水质变差,并对下游产生不利影响。

In order to understand the phytoplankton community structure characteristics and water quality status before and after the impoundment in Taihu Reservoir,water samples were collected to analyze the phytoplankton community structure characteristics and water quality status,and classify the phytoplankton functional groups before the impoundment(June 2014)and after the impoundment(March 2019).The results showed that 21 species of phytoplankton belonged to diatom were detected before the impoundment in Taihu Reservoir,while a total of 25 species of phytoplankton were detected after the impoundment.It had fluvial characteristics before the impoundment,whereas both fluvial and reservoir characteristics appeared after the impoundment.Before the impoundment,the Taihu Reservoir was classified into five functional groups,which were D,LO,MP,P and X3,respectively.After the impoundment,a total of 8 functional groups were classified into D,J,LO,MP,P,T,X1 and X3,respectively.The functional group succession of phytoplankton was obvious and it evolved form MP+P+D(before the impoundment)to P(after the impoundment).The RDA analysis was conducted to show WT,DO and CODCr were the main environmental factors affecting the distribution of phytoplankton in Taihu Reservoir before the impoundment,whereas TN,NO3-N,SS and SD were the main environmental factors after the impoundment.The diversity index and the comprehensive nutritional status index indicated that the Taihu Reservoir was in medium nutrition before and after the impoundment,and the water quality of the reservoir was deteriorated after the dam was built,which had an adverse impact on the downstream.