Abstract: The benthic meiofauna was quantitatively investigated from 19 stations in the sea areas of the First-phase Project of Yangshan Deepwater Port in November, 2005 and ten meiofauna groups, including nematodan, copepodan, polychaetan, bivalvian, ostracodan, amphipodan, tanaidacean,cumacean, gastropodan and foraminiferan, were recorded. Among them, the dominant fauna was nematodan with average abundance 154.05ind/(10 cm²); the following dominant ones in turn were ostracodan (58.37ind/(10 cm²)), foraminiferan(30.59ind/(10 cm²))and polychaetan(15.09ind/(10 cm²)). As to individual dry weights of meiofauna groups, the first four dominant biomass were foraminiferan(1 254.10ind/(10 cm²)), ostracodan(1 517.52ind/(10 cm2)), bivalvian(315.33ind/(10 cm²))and polychaetan(200.13ind/(10 cm²)); while nematodan lied below them with its biomass only 61.62ind/(10 cm²). There were differences of horizontal distribution between the abundance and biomass of meiofauna in 19 stations. The high abundance areas were presented from Luchao Port to Little Yangshan Island, and the high biomass areas were presented near Big and Little Yangshan Islands. Their distribution rules were not found, and the phenomena might be due to the large engineering project in East China Sea which has divided the whole distribution of meiofauna into several discontinuous parts. The results gained support from the analysis of unweighted pair-group method with arithmetic (UPGMA). The UPGMA analysisshowed that some separate stations had been brought together, which did not meet with the distribution rules of fauna. However, the high abundance of ostracodan and foraminiferan was distributed in deeper water while the high abundance of nematodan was presented in coastal water, and they could meet the distribution rules of these fauna groups.

Key words: meiofauna, abundance, biomass, distribution, Yangshan Deepwater Port, meiofauna, abundance, biomass, distribution