水生态学杂志Issue(2)：32-38,7.DOI:10.15928/j.1674-3075.2015.02.006
蟢湖北部底泥疏浚的生态效应研究
Ecological Effects of Dredging on Aquatic Ecosystem in Northern Gehu Lake
摘要
Abstract
Gehu Lake,with the total area of 164 km2 ,is the sixth largest fresh water lake in Jiangsu Province and the important component of lake groups in Taihu Lake basin.However,the whole Gehu Lake has degraded from macrophytic lake into algae type lake with frequent occurrence of cyanobacterial bloom in summer and is facing seri-ous ecological crisis because of land reclamation,large-scale reclamation aquaculture and cage culture.In 2011 and 2012,ecological dredging project in northern Gehu Lake was carried out to improve the water quality and eco-logical environment in Gehu Lake.The aim of our study was to investigate the ecological effects of dredging on a-quatic ecosystem in northern Gehu Lake,focusing on the spatial-temporal distribution of nutrients in bottom mud, the spatial-temporal variations of phytoplankton,zoobenthos,and aquatic macrophyte communities including species composition,density and biomass in dredged and un-dredged areas,which will provide scientific evidence for lake eutrophication control and ecological remediation.From October,2012 to September,2013,monthly sampling was made at eight sampling sites (site 1-site 3 in the dredged area and site 4-site 8 in the un-dredged area).1 L sur-face water sample was collected using water sampler for phytoplankton identification,fixed with Lugos′solution and settled for 48 h before microscopic examination.Bottom mud samples were collected with a Peterson bottom sampler (1 /16 m2 ),then screened and rinsed for zoobenthos identification,counting and weighing.All the emerged plant in a 1 m2 sampling plot were removed from the root and weighed;submerged plant,floating-leaved plant and float-ing plant were collected using grass clip,then identified and weighed after water rinsing.Bottom sediments (0 -5 cm)were collected with sediment corer,then dried and grinded for nutrient content determination,including the total organic carbon(TOC),total nitrogen(TN)and total phosphorous(TP).The results show that the average con-tents of TN,TP and organic matter in sediments of dredged areas were 0.65 g/kg,0.63 g/kg and 7.73 g/kg,de-creased by 51.4%,51.2% and 72.0%,respectively,comparing with those in the un-dredged areas,indicating that dredging was an effective approach for nutrients removal in sediments.The phytoplankton density and biomass in dredged areas were 379.6 ×104 -2 867.1 ×104 ind./L and 2.3 -10.0 mg/L,decreased by 19.8% -28.1%and 19.5% -50.2% comparing with those in the un-dredged areas.Especially,the density and biomass of cya-nobacteria were respectively reduced by 28.6% -39.5% and 31.8% -66.0% in dredged areas,which signifi-cantly decreased the risk of cyanobacteria bloom in northern Gehu Lake.The average density and biomass of oli-gochaetas,chironomids and mollusks in dredged areas were 94.3 ind./m2 and 0.52 g/m2 ,10.91 ind./m2 and 0.12 g/m2 ,0.54 ind./m2 and 0.55 g/m2 ,decreased respectively by 57.3% and 52.9%,by 91.8% and 82.8%,and by 91.8% -91.6% comparing with those in the un-dredged areas.Dredging project significantly in-fluenced the species diversity and biomass of chironomids and mollusks.The cover and biomass of macrophyte in dredged areas were 50.28% and 2.25 kg/m2 ,which were basically equivalent to those in un-dredged areas.The results indicate that dredging project is suitable to conduct in eutrophic lakes,which will improve the aquatic eco-logical environment by removing part proportion of surface sediments and suppressing phytoplankton growth.How-ever,dredging too deep will adversely influence the zoobenthos and aquatic macrophyte communities.关键词
底泥疏浚/沉积物/生态效应/蟢湖Key words
dredging/sediment/ecological effects/Gehu Lake分类
资源环境引用本文复制引用
吴沛沛,刘劲松,胡晓东,杨星,翁松干,李志清,郭刘超,吴苏舒..蟢湖北部底泥疏浚的生态效应研究[J].水生态学杂志,2015,(2):32-38,7.基金项目
江苏省科技计划项目（BM2014041）；江苏省水利科技项目（2013002；2014038；2014042）。 （）
