Studies on Macrobenthos in the Northern Waters of Liaodong Bay:I. Species Composition and Number Distribution

A total of 58 grabs were collected from 29 stations with a 0.1 m2 bottom sampler in the northern waters of Liaodong Bay (a semi-enclosed estuary in Liaoning Province) in July 2007,in which species composition and number distribution of macrobenthos were investigated.There were 79 macrobenthic species identified in the research region,which included 24 species of Polychaeta,19 species of Crustacea,24 species of Mollusca,6 species of Echinodermata,and 5 species belonging to other taxonomical groups.The dominant species in this region were relatively few and only 5 species whose dominance indices were higher than 1%.They were Potamocorbula laevis,Amphioplus japonicus,Cirolana japonensis,Nemertinea and Nassarius siquijorensis.There were patches with low and high species,and the inhabit density and biomass of macrobenthos were mutually nested.The average inhabit density of macrobenthos was 68.28 m -2 and the average biomass was 22.75 g/m2.The average inhabit densities of Mollusca,Polychaeta,Crustacea,and Echinodermata were 30.52,14.48,12.76,and 6.38 m -2,respectively,and the biomasses were 6.92,4.15,1.86,and 8.64 g/m2,respectively.Compared with previous results that the average biomass of macrobenthos in the Bohai Sea ranged from 10.29 g/m2 to 12.83 g/m2 in 1959,the average biomass of macrobenthos in present region significantly increased (16.45-22.75 g/m2 ),except for Laizhou Bay.