Community structure and diversity of macrobenthos in southern intertidal zone of Yellow River Delta,China

In May and August,2004- 2010,an investigation was conducted on the macrobenthos diversity in the southern intertidal zone of the Yellow River Delta. A total of 89 macrobenthos species were collected,most of which were polychaetes,crustacean,and mollusks,accounting for 34. 8%,29. 2% and 27. 0% of the total,respectively. Helice tientsinensis and Macrophthalmus japonicas were the dominant species in high tidal zone,while Potamocorbula laevis,Bullacta exarata,Umbonium thomasi,and Mactra veseriformis were dominated in mid and low tidal zones. The average Shannon index,Margalef index,and Pielou evenness index were1. 46,1. 15,and 0. 66,respectively,and the Shannon index and Pielou index showed an upward trend. The species distribution had an obvious difference in different tidal zones,but less difference among years,which was also shown by cluster analysis. Due to the changes of habitat conditions since 2005 when the dams were established,the bio-resources in the high tide zone increased obviously. As compared with historical data,the composition of dominant species in the study area in 2004- 2010 was relatively stable,but the polychaetes occupied larger proportion,which was related to the human activities and the eco-environment change.