Abstract: To assess the effects of thermal water discharged from coastal power plant on zooplankton, the sea area near Jiaxing Power Plant located at the coast of Zhejiang Province was selected as a case to investigate the zooplankton distribution during both spring and neap tides in May 2006. The thermal tolerance of Calanus sinicus, Sinocalanus tenellus, Acartiella sinensisand Corycaeus affinis, the common dominant copepods in coastal waters of East China Sea, were also determined by 24 h semilethal temperature. In total, 26 species of zooplankton were identified, among which, 22 species were in spring tide and 23 species in neap tide. The main species identified belonged to neritic low-salinity group, and Tortanus vermiculus and Labidorcera euchaeta were the dominant species. Zooplankton biomass increased from the close to the distant of coastline, while the density was relatively uniform. The biomass distribution was determined by Acanthomysis longirostrisand fish larval, while the density distribution was determined by T. vermiculus and L. euchaeta. No death was observed for the four species when the temperature was raised by 7 centigrade, suggesting that zooplankton had higher thermal tolerance. It was concluded that the thermal water discharged from coastal power plant had larger effects on the distribution of zooplankton species with stronger activities and higher masses near the outfall, but less effects on the species with weaker activities and lower masses.

Key words: Stow net, Generalized additive model, Environmental factor, Catch per unit effort (CPUE)