Keywords: 
• Dongzhai Harbor /
• zooplankton /
• dominant species /
• biomass /
• diversity /
• zooplanktonic larvae

Abstract: The zooplankton is an important part of ecosystem,including larvae of marine medicinal creatures. It is thus of theoretic and economic values to investigate the diversity of zooplankton in the waters of Dongzhai Harbor,Hainan,China. In June and December 2010,zooplankton in 25 sites of Dongzhai Harbor were sampled to analyze their changes in community structure and diversity. The investigation found 82 species of zooplankton,which belonged to six Phyla and 14 genera,of which Arthropoda was the main population（ 45 species）. The zooplankton species had a significantly greater number in December than in June,and the common dominant species were Canthocalanus pauper and Calanopia thompsonis in the two seasons. In June and December,the average biomass and average abundance were 97. 2 mg·m^-3and 131 ind·L^-1,131. 4 mg·m^-3and 99 ind·L^-1,respectively,and the spatial distribution of total biomass depended on dominant species. Two zones of high abundance were formed in each of the two seasons,but the total biomass of zooplankton had significant seasonal difference. The indexes of diversity and evenness were higher in winter（ 3. 129 and 0. 523） than in summer（ 2. 496 and 0. 449）,and the distribution pattern and density of zooplankton were obviously different in the two seasons. This indicates that temperature,salinity and the mangrove habitat be the main factors affecting the distribution of zooplankton in Dongzhai Harbor.