鄱阳湖典型河湖交汇区浮游植物现状分析

Analysis on the Current Situation of Phytoplankton in the Typical River⁃Lake Ecotone of Lake Poyang

鄱阳湖典型河湖交汇区(尾闾区)易受人类频繁活动的影响,属于敏感区且是蓝藻水华易暴发区域.为探究鄱阳湖典型河湖交汇区浮游植物群落结构的差异性及相关驱动机制,于2019年至2020年1月(枯水期)、 4月(涨水期)、 7月(丰水期)和10月(退水期)对鄱阳湖典型河湖交汇区7个采样点位和鄱阳湖河流中段6个采样点位以及主湖区1个采样点位水质状况和浮游植物进行野外调查.结果表明,鄱阳湖典型河湖交汇区浮游植物共有7门64属,浮游植物生物量和相对丰度以硅藻和蓝藻为主.鄱阳湖典型河湖交汇区生物量和丰度东部总体上高于西部,河湖交汇区生物量和丰度高于河流中段.湖区和河湖交汇区蓝藻门优势度较大,河流中段硅藻门优势度较大.蒙特卡罗检验结果显示:总氮(TN)、总磷(TP)、正磷酸盐(PO_(3-)_(4)-P)、水深(WD)、水温(WT)和透明度(SD)是影响浮游植物群落分布的显著相关环境因子.冗余分析(RDA)结果显示,鄱阳湖西部典型河湖交汇区受水化因子(TN、 TP和PO_(3-)_(4)-P)作用更明显,东部典型河湖交汇区水文因子(WT、 WD和SD)影响更为显著.鄱阳湖典型河湖交汇区浮游植物影响因子具有季节性,冬季受水化因子影响较大,夏季受水文因子影响较大.

The typical river⁃lake ecotone(tail end area)of Poyang Lake,which is a sensitive area and prone to outbreaks of cyanobacteria bloom,is vulnerable to frequent human activities.To explore the diversity of phytoplankton community structure and the relevant driving mechanism in the typical river lake junction area of Poyang Lake,the water quality and phytoplankton at seven sampling points in the typical river lake junction area of Poyang Lake,at six sampling points in the middle section of Poyang Lake River,and at one sampling point in the main lake area were investigated in the field from 2019 to 2020(dry season),April(flood season),July(wet season),and October(recession period).The results showed that there were seven phyla and 64 genera of phytoplankton in the typical river⁃lake ecotone of Poyang Lake,and the biomass and relative abundance of phytoplankton were dominated by diatoms and cyanobacteria.The biomass and abundance in the east of the typical river⁃lake ecotone of Poyang Lake were generally higher than those in the west,and the biomass and abundance in the river⁃lake ecotone were higher than those in the middle of the river.The dominant degree of cyanobacteria in the lake area and the river⁃lake ecotone was large,and the dominant degree of diatoms in the middle section of the river was large.The Monte Carlo test results showed that total nitrogen(TN),total phosphorus(TP),orthophosphate phosphorus(PO_(3-)_(4)⁃P),water depth(WD),water temperature(WT),and transparency(SD)were significantly related environmental factors affecting the distribution of the phytoplankton community.Redundancy analysis results showed that the typical river⁃lake ecotone in the west of Poyang Lake was highly affected by the hydration factors(TN,TP,and PO_(3-)_(4)⁃P),and the hydrological factors(WT,WD,and SD)in the typical river⁃lake ecotone in the east were highly significant.The impact factors of phytoplankton in the typical river⁃lake ecotone of Poyang Lake were seasonal,being greatly affected by hydration factors in winter and hydrological factors in summer.