神农架大九湖湿地浮游植物群落结构特征及营养状态评价

摘要

大九湖湿地是南水北调中线工程的重要水源涵养地之一.为了解实施生态修复工程后浮游植物群落结构特征及水质营养状态,于2014年11月-2015年9月进行了3次采样调查,综合营养状态指数表明水质处于中营养和轻度富营养化之间,水质富营化水平沿水流方向呈降低趋势;共采集浮游植物8门129种,11月优势种为绿藻门的四尾栅藻(Scenedesmus quadricauda)和硅藻门的颗粒直链藻(Melosira granulata)、短缝藻(Eunotia sp.);5月优势种为蓝藻门的纤细席藻(Phormidium tenue)、绿藻门的四尾栅藻(Scenedesmus quadricauda)和球衣藻(Chlamydomonas globosa Snow)、硅藻门的短线脆杆藻(Fragilaria brevistriata);9月优势种为蓝藻门的拟柱孢藻(Cylindrospermopsis raciborskii)、小形色球藻(Chroococcus minor)和泽丝藻(Limnothrix redekei),优势种主要为中污带指示种.冗余分析表明总磷和总氮浓度对浮游植物丰度变化有显著影响,温度和总磷浓度对浮游植物生物量有显著影响,蓝藻门和绿藻门的丰度和生物量均与总磷浓度呈正相关.%Dajiuhu wetland is a rare subtropical alpine in the central China.Dajiuhu wetland is the source of the Du River,a first-grade tributary of the Han River,and the wetland also serves as one of the important water conservation area of the middle routes of South-to-North Water Diversion Project.The human activities such as ditches digging,holes dredging and bog draining have led to severe degradation of ecological function and the shrinking of lake surface area in Dajiuhu wetland since 1986.Mter the implementation of'the Dajiuhu wetland protection and ecological restoration project'from 2005 until present,we conducted a field survey on the phytoplankton community and lake trophic status from November 2014 to September 2015 to reveal the status quo post the restoration project.Trophic status indices showed the water quality was between mesotrophy and light eutrophication.The water eutrophication level decreased along the water flow direction.A total of 129 phytoplankton species belonging 8 phyla were observed.Scenedesmus quadricauda,Melosira granulate and Eunotia sp.were the common dominant species in November 2014,and Phormidium tenue,Chlamydomonas globosa Snow,Scenedesmus quadricauda and Fragilaria brevistriata in May 2015;Limnothrix redekei,Cylindrospermopsis raciborskii,and Chroococcus minor in September 2015.All the dominant species were α or β-mesosaprobity species.Redundancy analyses indicated that total phosphorus and total nitrogen were the key drivers behind this difference of the phytoplankton abundance,while water temperature and total phosphorus showed significant effects on phytoplankton biomass.Redundancy analyses further showed a positive relationship between total phosphorus and the abundance (and biomass) of Cyanophyta or Chlorophya.