Studies On The Community Structure And Biodiversity Of Fresh Water Snails In Poyang Lake

To further study the community structure,seasonal variation and relationships between different habitats of freshwater snails in Poyang Lake, an extensive investigation was conducted on the freshwater snail resources of Poyang Lake from Apirl 2007 to November 2007 between flood water seasons and drought water seasons, the diversity of freshwater snails was also studied. The main results showed as follows:1. A total of 26 species belonging to 15 genera and 7 families of gastropoda were found. The dominant species were Bellamya aeruginosa,Parafossarulus striatulus and Semisulcospira cancellata. For faunal composition, Palaearctic Region and Oriental Region were each penetration.2. In flood water seasons, the frequency of B. aeruginosa was the highest(77.59 %), while that of Bellamya angularis and Hippeutis canton were the lowest(1.72%). The average individual number of P. striatulus in all stations was the highest (3.3±3.2). In drought water seasons, the frequency of B. aeruginosa was also the highest(72.22%), while Semisulcospira gredleri was the lowest(2.78%). The average individual number of Rivnlaria auriculata in all stations was the highest (3.6±3.1).3. The average biomass and density of freshwater snails in Poyang Lake were 77.28 g/m~2 and 109.69 ind./m~2. The biomass and density were 64.78 g/m~2 and 122.48 ind. /m~2 in flood water seasons, while those in drought water seasons were 89.78 g/m~2 and 96.89 ind./m~2 respectively.4. The Shannon-Wiener diversity index and Pielou uniformity index were used to analyze the diversity of the freshwater snail community. In flood water seasons, the diversity index and Pielou uniformity index were 1.23 and 0.89, species richness was 4.7±2.0. In drought water seasons, diversity index and Pielou uniformity index were 0.96 and 0.93, species richness was 3.0±1.4.5. Using the Hierarchical Cluster of between-groups linkage method, 18 cross-sections of flood water seasons were divided into four groups. Two typical groups were sand-soil group and water plant group, which contained the most and the least freshwater snails respectively.