Keywords: 
• Zooplankton community /
• shellfish culture /
• Li’an Lagoon /
• dry season

Abstract: Zooplankton communities in the shellfish-culture area and its adjacent non-culture area in Li’an Lagoon in the south of Hainan Island were observed to analyze their short-term temporal variation in dry season,and were found to have high abundance,species richness,significant dominant species and low evenness. In the zooplankton communities were identified 104 species of zooplankton and 14 species of planktonic larvae,which were under 6 phyla and 76 genera. The total abundance ranged from 114 ind·L^-1 to 735 ind·L^-1,including58%-77% protozoa,18%-30% copepods,and 1%-13% tunicate. The dominant species were mainly Acrocalanus gibber,Oithona brevicornis,Oikopleura（ vexillaria） dioica Harpacticoida,Favella ehrenbergi,Strombidinopsis acuminatum,Tintinnopsis lobiancoi,Globigerina quinqueloba and Helicostomella longa. The dominant species and dominance of the zooplankton showed temporal variation. The temporal pattern of the zooplankton in the shellfish culture area was similar to that in the adjacent non-culture area,but higher average abundance was observed in the non-culture area in the early month of the observation. Analysis of relationship between zooplankton communities and environmental factors showed that temperature,salinity and chlorophyll a were highly correlated to the zooplankton communities. The results demonstrated that apparent variations occurred in the community composition and abundance of the zooplankton even within one month in Li’an Lagoon. So it should be cautious to adopt the data from one single sampling time to represent long-term data in marine environmental research and monitoring.