The Community Structure And Diversity Analysis Of Phytoplankton In The Yellow Sea And The Chang Jiang Estuary Waters

In this study the phytoplankton community structure in the Yellow Sea and the Changjiang Estuary waters were investigated, which were mainly composed of species composition, quantity distribution, dominant species, biological diversity and physico-chemical factors affecting these parameters. 2 surveys were carried out in Spring, 2005 and Autumn, 2005 respectively.A total of 83 taxa were determined, belonging to 2 algae classes: Bacillariophyceae(74 species) and Phrrhophyta(9 species). Among them inshore species were the richest.The number of phytoplankton species in Autumn was higher than the one in Spring, which is 30 genera with 75 species and 24 genera with 55 species respectively. The species composition changed with obvious seasonal succession, and the Jaccard similarity index is 60.49%.Phytoplankton abundance in Spring ranged from 1.17×104 to 1281.69×104cells.m-3, averaged at 1139.29×104cells.m-3, and in Autumn from 0.057×104 to1151.91×104 cells.m-3, averaged at 75.45×104 cells.m-3. The abundance in Spring was much higher than the one in Autumn. The highest density was recorded in the Changjiang estuary waters in Spring, and in Autumn was located in the southern bay of Shandong Island and the the inshores of Subei. Dominant species varied from Spring survey to Autumn survey. The dominant species were Skeletonema costatum(Greville) Cleve, Chaetoceros debilis Cleve, Pseudonitzschia pungens Grunow, Rhizosolenia setigera Brightwell,etc. in Spring, and in Autumn the dominant species included Rhizosolenia alata f. indica(Péragallo) Ostenfeld, Chaetoceros lorenzianus Grunow, Chaetoceros curvisetus Cleve, Coscinodiscus radiatus Ehrenberg, Pseudonitzschia pungens Grunow and Skeletonema costatum(Greville) Cleve.The diversity indexes in Spring were lower than the ones in Autumn. In Spring, the Shannon-weiner index was 1.60; the lowest value occurred in the Changjiang estuary waters with an average of 0.97. In correspondence, the Shannon-weiner index was 1.64 and the lower value area moved north to the middle of South of Yellow Sea in Spring. The Margalef index in Spring was 0.78 with a higher value located in the south bay of Shandong Island and Subei inshores. In Autumn, the Margalef was 1.06 and distributed evenly. For the Pielou index, in Spring the value was 0.57 and in Autumn rose to 0.72.Multivariate analysis (MDS, CLUSTER,ANOSIM)by using software PRIMER 5.0 on the phytoplankton showed that the 48 sampling stations can be classified into three groups(I,II,III in Spring and AI,AII,AIII in Autumn) by the cluster analysis based on species composition. The cell abundance and dominant species in three groups differed from each other.PCA and BIO-ENV analysis of the environmental factors showed that the factors affecting the species composition and the abundance distribution in Spring were salinity, surface PO4 and other nutrients, and in Autumn the factors were mainly surface temperature and salinity. Referring to the previous works, in Spring, three groups can be distinguished: I, Yellow Sea Netric group; II, the Yellow Sea Central group; III, the Yellow Sea and East Sea Mixed water group. Otherwise, in Autumn, there was a little difference, and the following groups were divided: AI, the Yellow Sea Northern group; II, the Yellow Sea Central group; III, the Yellow Sea and East Sea Mixed water group.