Effects Of Environmental Factors On Scapharca Subcrenata Larvae Of Guangdong Raoping Populations And Juveniles Of Fujian Zhangzhou Populations

Scapharca subcrenata is an important marine economic shellfish in China.Due to the effects of overfishing and habitat destruction,the gross resources and production of raccoon began to decline drastically and it is far from meeting the market demand.In this study,one-way analysis of variance was used to investigate the effects of different environmental factors on the hatching rate and larval spat of Fijian populations.Response surface analysis was used to find the optimal growth condition combination.The study had the following main results:1.Effect of environmental factors on early growth and development of Scapharca subcrenataThe optimum incubation temperature of Scapharca subcrenata fertilized egg was around21~29°C,17~29°C and 21~29°C were the optimal survival and growth temperature range for Scapharca subcrenata planktonic larvae,respectively.The optimum incubation salinity of Scapharca subcrenata fertilized egg was around 19~29,14~29 was the optimal survival and growth temperature range for Scapharca subcrenata planktonic larvae.The optimum incubation density of Scapharca subcrenata fertilized egg was around 5~20 ind/mL.The appropriate breeding density for the planktonic larvae was 5~10 ind/mL.The optimum incubation pH of Scapharca subcrenata fertilized egg was around 6.8~8.4.7.2~8.4 was the optimum pH range for Scapharca subcrenata planktonic larvae.2.Effect of environmental factors on growth and development of juveniles Scapharca subcrenataThe optimal temperature range for Scapharca subcrenata juvenile was 21~33°C,with an optimum temperature of 25~29°C.The optima salinity range for Scapharca subcrenata juvenile is 14~34.The optimal growth density range for Scapharca subcrenata juvenile was0.6~2.4 ind/cm~2.Density has no effect on survival of Scapharca subcrenata juvenile.For Scapharca subcrenata juvenile,Dicrateria sp.with Chlorella sp.at the rate of 1:1 obtained the best feeding result.Pure mud substrate had significantly higher growth rate,survival rate for the larvae than substrate contained sand.Under different substrate to breeding Scapharca subcrenata juvenile,mud with sand at the rate of 2:1 obtained the best growth,and pure mud obtained the survival rate.Suitable substrate for the juvenile should be mud with sand which sediment was more than 67%.3.Response surface methodology to analyze the effect of interaction temperature,salinity and mud percentage on the shell length growth of juveniles Scapharca subcrenataThe optimum temperature,salinity and mud percentage for juvenile growth of Scapular subcutaneous were determined through the response surface methodology(RSM).The multivariate nonlinear model was applied to study the interactions and optimization of the growth parameters for Scapharca subcrenata which were explored by experiments.there were no significant interactions between temperature,salinity and mud percentage for the growth of juveniles.The multivariate non-linear model is as follows:Y=7.35+0.16A+0.035B+0.15C-0.017AC-0.035BC-0.39A~2-0.12B~2-0.24C~2(R~2=0.9938),the optimum conditions for germination are as follows:temperature 25.8?and salinity 24.4 and mud percentage 76.26%.