Preliminary investigations on the Distribution and growth of Corbicula fluminea in the Dianshan Lake of Shanghai

Abstract:

Distribution of Corbicula fluminea in the Dianshan lake was investigated by sediment sampling conducted on 28th June of 2010. Results of distribution survey revealed that C. fluminea in the southeast area (average density 62.3ind./m2，average biomass 62.7 g/m2) is more abundant than the northwest area (average density 13.8 ind./m2，average biomass 12.8 g/m2), and the highest density was found at a southeast tunnel connected with the lake (average density 318.5ind./m2，average biomass 225.2 g/m2). Population dynamics of C. fluminea in the Dianshan Lake was investigated by monthly collection of clam specimens from January to December of 2011. Results showed that, large numbers of juvenile C. fluminea (shell length < 8mm) presented in June, therefore, June can be identified as the peak reproduction season of C. fluminea in the Dianshan Lake. Shell length of C. fluminea increased to 19mm one year after settlement, and then increased to 27mm two years after settlement, only very low percentage of individuals can survive more than two years after settlement. The life span of C. fluminea is estimated as 2-3 years after settlement. Theoretically the largest individual is estimated as 30mm in shell length, whereas practically the largest individual was measured as 34mm in shell length. Data on the distribution and population dynamics of C. fluminea in the Dianshan Lake can be significantly important to the conservation of this species within this area.