长江口南北支浮游动物群落生态学研究

长江口特殊的生态环境使得浮游动物的种类组成、密度和时空分布等生态特征有别于其它水体。2005年秋季（丰水期）和2006年春季（枯水期）对长江口南北支浮游动物进行了2个航次的调查,沿南北支由西向东设立3个采样断面共20个采样点。共采集到浮游动物227种,其中轮虫65种,原生动物107种,枝角类15种,桡足类40种。优势种包括龟甲轮虫（Keratella）、刺簇多肢轮虫（Polyarthra trigla）、萼花臂尾轮虫（Brachionus calyciflorus）、砂壳虫（Difflugia）、表壳虫（Arcella）、砂壳纤毛虫（Tintinnid）、中华哲水蚤（Calanus sinicus）、汤匙华哲水蚤（Sinocalanus dorrii）、广布中剑水蚤（Mesocyclops leuckarti）、象鼻溞（Bosmina）等。文章对南北两支浮游动物的种类组成和结构进行了比较,南支浮游动物的种类、数量及生物多样都高于北支,南北两支的浮游动物群落相似度很低。南北两支水域环境的不同造成其浮游动物群落结构的较大差异,文章分析了环境因子与浮游动物群落结构的相关性,其中水温是重要的影响因素,水温的季节性决定了浮游动物在时间分布上的变化。盐度对浮游动物群落结构的影响主要决定了其物种生态类型及空间分布。从整体上看,南北支主要受长江径流控制,浮游动物的种类组成以淡水种为主,咸水种在断面3出现较多。

Zooplankton community ecology in north and south branches at Yangtze River estuary

The special ecological environment at Yangtze River estuary makes zooplankton there different from other water in ecological characteristics such as species composition,density and time-space distribution etc.Two times＇ investigations were taken in spring（drought season） and autumn（raining season） from2005 to 2006 along the north and south branches,where three cross-section and 20 survey points were set.A total of 227 zooplankton species were identified,with 65 species of rotifers,107species of protozoas,15 species of cladocerans and 40 species of copepods.The Keratella,Polyarthra trigla,Brachionus calyciflorus,Difflugia,Arcella,tintinnid,Calanus sinicus,Sinocalanus dorrii,Mesocyclops leuckarti and Bosmina ect were the dominant species.This paper compared the species composition and structure of two branches.The zooplankton species,quantity and biomass in south branch is higher than that in north branch.Zooplankton community similarity in two branches is very low.The different environmental caused much different zooplankton community structure.Correlationship of zooplankton community structure and environmental factors were analyzed,among which water temperature was the important factor that determined the time distribution of zooplankton with seasonal change.The salinity influenced the ecological types and space distribution of zooplankton community structure.As a whole,the north and south branches were controled by Yangtze river,so that the zooplankton species were mainly rever-type and the salt-type appeared more in section 3.