Ecological And Taxonomic Studies Of Molluscs Communities In Three Wetlands On Qi’ao Island, Pearl River Estuary, China

A long term (biomonthly from Jan.2008to Nov.2010) studies in3differenttypes of wetlands (mangrove arbor, a tidal river, and an artificial lake) atQi’ao-Dan’gan I., revealed significant variations of species number, abundancebiomass and community structure, and no significant variations of temporal variation,and the relations with environment factors.During this period,16species consisting of11species of gastropods and5species of bivalves were found in total. All of the bivalve species were found amongthe seaweeds. Total abundances of mollusks were1824ind./m2,1736ind./m2and112ind./m2at SW, MA and EP respectively, the average annual abundances of threewetlands was68ind./m2. The situations of kinds of biodiversity indexs for molluscscommunity were: Mean total species number (S): MA (2.82)> SW(2.47)> EP (1.33);the trend of mean Margalef’s species richness (D)、Shannon-Winner’s diversity index(H’)，Pielou’s eveness index (J’) were the same as the mean total species number: MA> SW> EP. The community composition significantly differed among these wetland types (p<0.05), The dissimilarity of community structure among three wetlands were MA vsSW> SW vs EP> EP vs MA.ANOSIM showed the mollusc community compositions exhibited no significantdifferences at three different wetlands in different seasons or different years. TheRELATE test found that there was a significant serial shift occurred during the3rdyear of sampling in the SW wetland. SIMPER found this serial shift were contributedto the decline of abundance of Melanoides tuberculata (Müller,1774) and theincrease of abundance of Potamocorbula sp..In this article, relationships between the distribution of molluscs andenvironmental parameters are discussed as well. BEST/BIOENV found the bestenvironmental parameter was S-TN.The taxonomic study of the molluscs on Qi’ao Island in the Pearl River estuarydecribed2new records species of China including Assiminea estuarine Habe,1946and Iravadia (Fairbankia) cochinchinensis Bavey&Dautzenberg,1910and1speciesCerithidea sinensis Philippi,1848was found in tropical zone for the first time andsome of other species in this article including Sphaerassiminea brevicula Pfeiffer,1855, Taiwanassiminea sp., Melanoides tuberculata (Müller,1774), Laemodontapunctigera (H.&A. Adams,1853), Iravadia (Iravadia) ornata (Blanford),1867,Potamocorbula amurensis (Schrenck,1867), Potamocorbula sp. and Abra sp..