Morphology,Environmental Adaptation And Nutrition Quality Analysis Of Different Wild Populations Of Cyclina Sinensis

The clam(Cyclina sinensis)belongs to Lamellibranchia,Heterodont Venerida,Veneridae,and Cyclina in the taxonomic.It is one of the important economical shellfish and widely distributed in the costal of China.With the problems such as overfishing,poor breeding effect and inbreeding in recent years,the germplasm resources of C.sinensis has become increasingly degraded.This thesis attempts to explore the differences in many aspects of domestic wild populations of C.sinensis,focusing on the analysis and comparison of the morphology,environmental adaptability and nutritional quality of different wild populations of the clam C.sinensis.The research aims to provide a theoretical research basis for the genetics of the clam C.sinensis,it can also provide reference for the transplantation,production,cultivation and protection of germplasm resources.The main findings of this study are as follows:1.Correlation and path analysis of quantitative traits among different wild populations of C.sinensisCorrelation analysis was carried out on the traits of eleven wild populations of clam C.sinensis collected in coastal areas of China,and it was found that there were differences in the degree of correlation between different traits in each population,indicating that different populations were not consistent in morphology.In all groups,seven morphological traits,such as shell length,shell height,shell width,the distance from the top of the shell to the front and rear of the shell,and the distance from the end of the external ligament to the front of the shell and the bottom of the ventral margin,were significantly correlated with the body weight(P<0.01).The path analysis method was used to obtain the morphological characters that have the main influence on the body weight of each populations.And through the direct and indirect effects of the main morphological characters on the body weight,the optimal multiple regression equation with the body weight as the dependent variable were established for different populations.2.Comparison of environmental adaptability of five wild populations of C.sinensisIn the study of the environmental adaptability of 5 wild populations of the clam C.sinensis,it was found that there was no significant difference in the mass growth index between different groups(P>0.05),but the growth rates of shell length,shell height and shell width were significantly different(P<0.05).Dandong,Tianjin,and Yancheng populations had better growth performance of the relative indexes of shell length and shell height,while the Wenzhou population had poor performance of the relative growth indexes of shell length and shell height,which reflected from the side that morphological characters that mainly affect the body weight of different populations are not the same.There were great differences in survival rate among the 5populations.The Yancheng population had the highest survival rate(65.86±0.57)%,and the Wenzhou population had the lowest survival rate(29.90±2.40)%,which was significantly lower than the other 4 groups(P<0.05).The five populations were able to adapt to the local environment after the one-year transplant period,and achieved the overall synchronization of the breeding period,which provided great convenience for the hybrid breeding of the clam C.sinensis.The study also found that the populations with higher gonadal index also performed better in terms of condition factor,indicating that there is a great correlation between condition factor and gonadal index of the clam C.sinensis.Judging from the condition factor and glycogen content of different parts,the Dandong population has more advantages in energy storage,which also means that Dandong population may have more advantages more advantages in the metabolic performance in the subsequent autumn and winter.The results showed that the overall glycogen content of male clams was higher than that of female clams.It was speculated that the energy storage capacity of male clams was better than that of female clams,and they had stronger adaptability to the environment.3.Comparison of environmental adaptability of five wild populations of C.sinensisThe types of fatty acids and amino acids in different wild populations of the clam C.sinensis are the same,but the content were different.The soft tissue of different populations are rich in saturated fatty acids,mainly C16:0.The content of EPA and DHA in polyunsaturated fatty acids is high,indicating that the clam C.sinensis in different populations have higher nutritional value.All populations have the nutritional characteristics of high total amino acid content,and the proportion of umami amino acids is high,indicating that the clam has excellent flavor.The results showed that the ratios of EAA/TAA and NEAA/TAA in the soft tissue of different populations before and after transplantation were all up to standard of FAO/WHO ideal protein model evaluation,indicating that each population of the clam C.sinensis was a high-quality protein source.In addition,the results of the study showed that one-year of stocking in the same environment could not completely eliminate the nutritional differences among the five populations,and only a few populations had significant increases in the content of some nutritional indicators compared with those before transplantation.The results show that the bait conditions in the Lianyungang sea area have shortcomings compared with the original growth environment,and it is necessary to improve the nutritional quality of the clam C.sinensis such as improving the quality of the bait in the later stage.