Diel Vertical Migration of Crustacean Zooplankton in Lake Zixia and Analysis of Its Impacted Factors

Diel vertical migration (DVM) of the crustacean zooplankton was investigated from September 19 to 21, 2010 in Lake Zixia, Nanjing.The factors impacting on DVM were also analyzed.The depth of the site for DVM investigation was 8.5 m.The physiochemical factors, chlorophyll.a and fish composition were measured for analyzing the possible factors impacting the DVM.The results showed that Diaphanosona orghidani, Bosmina sp.,Bosminopsis deitersi,Thermocyclops taihokuensis and adult Eodiapotomus sinensis had evident diel vertical migration.Nauplii and juveniles of Eodiapotomus sinensis showed no diel vertical migration.The analysis indicated that temperature, dissolved oxygen and cholorophyll a were not the main factors for diel vertical migration;light intensity and fish predation were important factors affecting the diel vertical migration of crustacean zooplankton.