Characteristics of Zooplankton Community and Its Relation to Environmental Factors in Lake Wuhu in Spring and Autumn

Investigations of zooplankton were carried out during four surveys in Lake Wuhu in spring(May) and autumn(November) of 2007 and 2008.Totally,133 species of zooplankton including 61 species of protozoa,63 species of rotifers,6 species of cladocerans and 3 species of copepods were found.The number of zooplankton species in spring(86 and 85,respectively) was higher than in autumn(73 and 72,respectively).The density of zooplankton was the highest in spring of 2007(49 605 ind./L) while the low density of zooplankton occurred in autumn of 2007,spring and autumn of 2008;and the protozoa and rotifer were predominated.Relationship between zooplankton community characteristics and water quality parameters were analyzed by canonical correspondence analysis(CCA).The analysis showed that temperature,transparency and the concentrations of Chl a,TP,TN,COD and DO were strongly correlated with the zooplankton community.The parameters that demonstrated a strong correlation to the zooplankton community differed among seasons,suggesting that the seasonal variations of zooplankton community structure were related closely to the water trophic status.