疏浚后杭州西湖浮游动物群落的变化

2003年1-12月调查了疏浚后杭州两湖(小型、浅水、富营养化湖泊)四个采样站(Ⅰ-Ⅳ)浮游动物群落的变化。研究包括优势种组成、密度和生物量,以及浮游动物生物量与水体叶绿素a、有机物耗氧量、总氮和总磷含量之间的相关分析。疏浚后,Ⅲ-Ⅳ站原生动物第一优势种由似铃壳虫(Tintinnopsis sp.)变为筒壳虫(Tintinnidium sp.);Ⅲ-Ⅳ站轮虫第一优势种由暗小异尾轮虫(Trichocerca pusilla)变为针簇多肢轮虫(Polyarthra trigla);Ⅰ站的长额象鼻溞(Bosmina longirostris)和Ⅲ站的微型裸腹溞(Moina micrura)分别取代了长肢秀体溞(Diaphanosoma leuchtenbergianum)第一优势种的地位;桡足类中,剑水蚤优势种为粗壮温剑水蚤(Thermocyclops dybowskii),哲水蚤优势种为汤匙华哲水蚤(Sinocalanus dorrii)。疏浚后,西湖浮游动物平均密度增加了80.5%,其中原生动物密度增量贡献57.3%。平均生物量增加了49.7%,其中轮虫生物量增量贡献36.5%。西湖浮游动物生物量与水体叶绿素a、有机物耗氧量和总磷含量之间均呈垃著的正相关关系。不同采样站中,以Ⅳ站环境生态因子与浮游动物生物量之间的相关程度最高,其次为Ⅲ站、Ⅰ站和Ⅱ站,水体环境生态因子对浮游动物的影响程度与其优势利演变的体现相一致。在不同浮游动物类群中,枝角类生物量与水质生态因子之间的相关程度最高,其次为轮虫、桡足类和原生动物。

A change of zooplankton community after dredging in the West Lake, Hangzhou

Ecology of zooplankton community, including dominant species composition, density, biomass, and regression analysis amomg zooplankton biomass and the water quality factors were studied at four sampling stations (Ⅰ-Ⅳ) of the West Lake, Hangzhou, a shallow eutrophic lake.After dredging, Tintinnopsis sp., which was the first dominant species of Protozoa replaced by Tintinnidium sp., and Trichocerca pusilla replaced by Polyarthra trigla at stations Ⅲ-Ⅳ.Diaphanosoma leuchtenbergianum, which was the first dominant species of Cladocera replaced by Bosmina longirostris at Station Ⅰ and by Moina micrura at Station Ⅲ.Thermocyclops dybowskii dominated the Cyclopida, and Sinocalanus dorrii dominated the Calanoida after dredging.The annual average density of zooplankton increased 80.5%, of which 57.3% was contributed by protozoans.And the annual average biomass of zooplankton increased 49.7%, of which 36.5% was contributed by rotifers.There had a positive linear relationship between biomass of zooplankton and Chlorophyll-a, COD_Mn and total phosphorus content in the West Lake, Hangzhou after dredging.The relative degrees of the biomass and environmental factors were differed in each sampling station of the West Lake with an order of: Ⅳ>Ⅲ>Ⅰ>Ⅱ.The influence degrees of environmental factors on zooplankton was coincidence with appearance of dominant species changes.The relative degrees of the biomass and environmental factors were differed in each group of zooplankton with an order of: Cladocera>Rotifer>Copepoda>Protozoa.