In order to understand intertidal shellfish ecology situation of the Dongji Island, and provide basic in-formation about Zhejiang basic community structure of marine ecosystems, we collected intertidal shellfish from April 2010 to April 2011. The shellfish species composition, distribution, ecological characteristics and diversity of situations are reported. The results show that there are 33 species of shellfish, belonging to 3 classes, 7 orders, and 20 families. According to the nature of temperature adaptation, shellfish are divided into three groups. There are 15 wide temperature widespread species (45.5%), 4 temperate species (12.1%), and 14 ubtropical species (42.4%). The yearly average biomass was 1541.8 g/m2, exhibiting an increasing trend from high tide to low tide . The yearly av-erage density was 925.2 ind/m2 with the highest value in the middle zone. The biomass and density both had the highest value in summer. The biomass has the lowest value in autumn and the density has the lowest value in spring. Shannon-Wiener Diversity index (H ') is from 0.9 to 3.0. Pielou evenness index (J) is from 0.2 to 0.8. The results show that the species is rich and the density is high in the Dongji Island, which means the geographical environment is suitable for shellfish growing. The species distribution is even and the ecological environment is stable in the Dongji Island.%为了解东极岛潮间带贝类生态状况,为浙江海洋生态系统基本群落结构提供基础资料,于2010年4月至2011年4月的大潮期间,在舟山东极岛潮间带采集贝类,调查了解贝类的种类组成、数量分布、生态特点、多样性情况。研究分析发现,东极岛潮间带贝类33种,隶属3纲7目20科。根据温度适应性质分,东极岛潮间带贝类属于3个类群：广温广布种15种,占45.5%；温带种4种,占12.1%；亚热带种14种,占42.4%。东极岛潮间带贝类四季平均生物量为1541.8 g/m2,由高潮带向低潮带呈递增趋势；四季平均栖息密度为925.2个/m2,以中潮带最高,向高潮带和低潮带递减。季节变化中生物量由大到小依次为夏季、春季、冬季、秋季,栖息密度由大到小依次为夏季、秋季、冬季、春季。多样性指数(H′)为0.9~3.0,均匀度指数(J)为0.2~0.8。结果表明东极岛种类丰富,生物量和栖息密度较高,说明东极岛地理环境较好,适宜贝类生存；物种分布均匀,生态环境稳定。
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