Abstract: To reveal the variations of the structure of macrobenthic communities in the intertidal zone of Xiaoqing River estuary and the effects of coastal protection dam and sea ice, annual samplings of macrobenthos were carried out in each spring from 2004 to 2015. Species composition, biomass, abundance, and biodiversity indices of macrobenthos were analyzed. The results showed that a total of 108 species were identified in the past 12 years. The whole collections were divided into five main groups based on cluster analysis. Samples in 2004 before dam construction and samples in 2013 which were less affected by the dam construction and sea ice disaster, were identified as two separate groups. Macrobenthic communities were significantly affected during the dam construction in 2005-2008, the samples from which were identified as a group. Samples in the period of 2009-2012 after the dam construction were identified as a group, during which macrobenthic communities were mainly influenced by sea ice. Samples in 2014 and 2015 were merged into one group, in which the communities tended to be stable. The abundance and biomass ranged from 218 to 1522 ind·m^-2 and 31.83 g·m^-2 to 123.41 g·m^-2, respectively. Species richness index (d), evenness index (J) and Shannon diversity index (H) were 3.12, 0.51 and 2.55, respectively. Abundance/biomass curves showed that the macrobenthic assemblages were under moderate to severe disturbance due to the construction of coastal protection dam and sea ice disaster.

Key words: irrigation frequency, yield, organic nutrient solution, quality, fertilizer and water use efficiency, photosynthesis