Spatial And Temporal Distribution Of Macrobenthos In North Branch Of Yangze River Estuary And Adjacent Sea

From 2012 to 2013 we take research for macrobenthos in four seasons in the northern branch of Yangze River and in 2013 we do research in Yangshan Port in order to analyze variation of seasons、temporal and relationship between environmental factors and community. Results show:1.62 species had been taken in north branch of Yangze River for four seasons. Amongspecies,Mollusc(20)=Arthropoda(20)>Chordata(14)>Annelida(7)>Nemertea(1), summer(33)>autumn(23)>spring(19)>winter(18). Also there are 5 dominant species and some changed in contrast with previous research.There is some difference in seasonal density and the variation is winter>spring>summer>autumn and all kinds’ proportion differs gteatly. So as seasonal biomass and difference is winter>spring> summer>autumn. Seasonal diversity index differs greatly and Shannon.wiener index has same trend with Margelaf for summer>autumn>winter>spring. But Pielou index has trend for autumn>summer>spring>wunter. Seasonal community differs greatly and individuals become small, moreover environment became worse.2.48 species had been taken in Yangshan Port and Arthropoda(27)> Chordata(12) > Mollusc(7)>Annelida(1)>Others(1). Seasonal species is different for summer(28) >autumn(22) >spring(17) >winter(8) and all kinds’ proportion differs greatly.Dominant species differ greatly and the number is 7,besides, Exopalamon palaemon carincauda appears each season. With influence of season and environment, seasonal density differs greatly(P<0.05) for summer>autumn>spring>winter. Shannon.wiener index has the same with Pielou index for winter> summer> spring> autumn, but for Margelaf index is summer>autumn>spring>winter. Each smple’s diversity index has the same trend with seasons, just for the same between Shannon.Wiener and Pielou index and temporal composition differs greatly. Furthermore each sample trends regional distribution. Epifauna commposition is obvious.3.42 species had been taken for infauna in Yangshan Port : Annelida(19) > Mollusc(12) > Arthropoda(8) > Asteroidea(2) >Others(1). Except for autumn,other seasons are not far more similar.:autumn(28) > winter(18) > summer(17) > spring(15). Dominant species in four seasons are different and total number is 8, but Magelona cincta is present each season and dominant species vary greatly. Seasonal density differs more(P<0.05): summer>autumn>winter>spring. Seasonal Shannon,Wiener idex has same trend with Pielou index :spring >autumn >summer >winter. Variation of Margelaf index is autumn?spring>winter>summer. For each sample Shannon.Wiener index has same trend with Pielou index,but Margelaf index is different. Infauna composition vary with season and seasonal difference is obvious.4.Temperature、p H、DO、TSS、NTU and TN have obvious relationship with macrobenthos in north branch of Yangze River and Temperature、p H、Do、NTU and TN are more. In spring TN is the most,and second is BOD and salinity, but the worse is TSS. In summer salinity is the best,second is TN but last is NTU.Between atutumn and winter, TSS is the best.For infauna,TN is best in spring, next is NTU, last is DO; In summer NTU is best and last is TN; In autumn BOD is best and next is DO and COD but last is TN; In winter TN is the best and next is DO and COD but last is p H. The influence of environmental factors depends on seasonal difference, and benthos composition is influenced by factors more,besides, sediment and TSS is the main.