Meta-zooplankton community structure and its relationship with environmental factors in Wenruitang River
温瑞塘河后生浮游动物群落结构及其与环境因子的关系

A seasonal investigation of meta-zooplankton was undertaken from January to July 2011 in Wenruitang River,Zhejiang.A total of 24 meta-zooplankton species were identified,including 15 Rotifera,6 Cladocera and 3 Copepoda.Dominant species included Brachionus calyciflorus,B.urceus,B.falcaty,Asplanchna priodonta,Filinia longiseta,Rataria neptunia,Schmackeria inopinus,Microcyclops leuckarti and Moina macrocopa,and the dominant species composition acrossed different sites in different seasons.Monthly mean densities of zooplankton ranged from 13.39 to 310.8 ind./L,and the biomass changed from 0.29 to 26.04 mg/L,both of which increased with water temperature.The density and biomass of zooplankton were significantly different in ten sites during investigation.According to the canonical correspondence analysis(CCA),the distribution of zooplankton was affected by ammonia nitrogen(NH+4),total nitrogen(TN),water temperature(Wt),chemical oxygen demand(CODMn),dissolved oxygen(DO),nitrite(NO-2),nitrate(NO-3) and chlorophyll(Chl-a).Among them,water temperature was the main factor and was significantly positively correlated with the density of zooplankton(P≤0.05).In addition,the density could also be affected to some extent by CODMn,TN and NH+4.Therefore,more attentions should be paid to the distribution of COD and NH+4 in Wentuitang River during improving the river water environment.