Study On Regional Difference Of Stable Isotope And Fatty Acid Compositions Of Marine Benthonic Animals

In this paper, the stable carbon and nitrogen isotope compositions, fatty acid profiles, as well as stable carbon isotope compositions of individual fatty acids of marine benthonic animals such as sea cucumber (Apostichopus japonicus)and scallops (Patinopecten yesoensis and Chlamys farreri) in the coastal areas of China(Liaoning, Hebei, Shandong, Jiangsu and Fujian) were studied to analyze and compare the regional differences in stable isotope and fatty acid compositions of Apostichopus japonicus and scallops. Moreover, statistical analysis methods such as principal component analysis (PCA) and discriminant analysis (DA) were applied to distinguish between different origins of Apostichopus japonicus and scallops.Furthermore, the contribution rate of potential food source, the composition of food source and the fractionation process of stable carbon isotope of fatty acids were studied to evaluate the effects of food source and fatty acid metabolism on stable isotope and fatty acid compositions of Apostichopus japonicus and scallops, which will provide a theoretical basis for further analysis of regional difference in stable isotope and fatty acid compositions in marine benthonic animals.There were significant differences in the stable carbon and nitrogen isotope compositions of Apostichopus japonicus and scallops in different areas. The stable carbon and nitrogen isotope compositions can effectively discriminate between different origins of Apostichopus japonicus and scallops. Moreover, there were significant differences in the stable carbon and nitrogen isotope compositions of Apostichopus japonicus and scallops in different seasons. The ?13C and ?15N values of Apostichopus japonicus in autumn were higher than that in spring (?13C:0.066?2.310‰; ?15N: 0.527?1.246‰), while the ?13C values of Patinopecten yesoensis and Chlamys farreri in autumn were lower than that in spring (0.081?1.861‰and 0.201?1.566‰ respectively).The fatty acid compositions of marine benthonic animals reflect obvious species specificity, The fatty acid compositions of marine benthonic animals with different feeding habits are different. There were significant differences in the fatty acid compositions of Apostichopus japonicus and scallops in different regions. The fatty acid compositions, combined with statistical analysis methods can effectively distinguish between different origins of Apostichopus japonicus and scallops. There were significant differences in the fatty acid compositions of Apostichopus japonicus and scallops in different seasons. Moreover, there were also significant differences in the fatty acid compositions of Apostichopus japonicus with different farming methods.The ?13C values of saturated fatty acids were generally higher than that of unsaturated fatty acids. There were significant differences in the stable carbon isotope compositions of fatty acids of Apostichopus japonicus and scallops in different regions. The stable carbon isotope compositions of fatty acids,combined with statistical analysis methods can effectively distinguish between different origins of Apostichopus japonicus and scallops. There were significant differences in the stable carbon isotope compositions of fatty acids of Apostichopus japonicus and scallops in different seasons. The ?13C values of individual fatty acids of Apostichopus japonicus in autumn were higher than that in spring, while the 813C values of individual fatty acids of Patinopecten yesoensis and Chlamys farreri in autumn were lower than that in spring, which were consistent with the bulk 813C values of Apostichopus japonicus and scallops between seasons. Moreover, there were also significant differences in the stable carbon isotope compositions of fatty acids of Apostichopus japonicuswith different farming methods. The 813C values of individual fatty acids of stable breeding were higher than that of bottom sowing culture.There were significant differences in the stable carbon and nitrogen isotope compositions between potential food sources in different areas. Moreover, there were significant differences in the contribution of four potential food sources to the growth of Apostichopus japonicus. The relative contribution rates of the four potential food sources to the growth of Apostichopus japonicus in descending were macroalgae,Mytilus galloprovincialis, plankton and SOM in Laizhou, and SOM, plankton,macroalgae and Mytilus galloprovincialis in DZD, and SOM, macroalgae, Mytilus galloprovincialis and plankton in ZZD. The differences of the stable carbon and nitrogen isotope compositions of potential food sources and the contribution of potential food sources to the growth of marine benthonic animals are the main reason for the regional differences of stable carbon and nitrogen isotope compositions of marine benthonic animals.The food sources of marine benthonic animals with different feeding habits are different. The main food source of Apostichopus japonicus is diatoms, while the main food sources of scallops are diatoms and flagellates. However, the main food source between the two scallops is slightly different. The main food source of Patinopecten yesoensis is diatoms, while the main food source of Chlamys farreri is flagellates. The differences in the compositions of food sources of Apostichopus japonicus and scallops in different regions lead to significant regional differences in fatty acid compositions of Apostichopus japonicus and scallops.The stable carbon isotope fractionation of fatty acids of Apostichopus japonicas was 11.588-7.403‰, of which the stable carbon isotope fractionation of saturated fatty acids was 1.098?7.403‰,and the stable carbon isotope fractionation of monounsaturated fatty acids was -1.588?2.778‰, and the stable carbon isotope fractionation of polyunsaturated fatty acids was -1.559?5.614‰. The degree of fractionation of stable carbon isotopes of saturated fatty acids is greater than that of unsaturated fatty acids. There is a difference in source and metabolism between fatty acids in Apostichopus japonicus. The saturated fatty acids of Apostichopus japonicus are mainly derived from food, and the even-carbon saturated fatty acids less than 20 carbon atoms can be used to synthesize other fatty acids by desaturation and carbon chain extension in Apostichopus japonicus. The monounsaturated fatty acids less than 20 carbon atoms are mainly derived from food, while that more than 20 carbon atoms are mainly derived from transformation and synthesis of other fatty acids. The polyunsaturated fatty acids of 18:3n-3, 20:5n-3 and 20:3n-6 are mainly derived from food,of which 18:3n-3 and 20:5n-3 participated in metabolic reactions for the synthesis of other fatty acids or hormones. 20:4n-6 is mainly derived from the transformation and synthesis of 18:2n-6, and 22:6n-3 is derived from both food and the transformation and synthesis of 18:3n-3.The stable isotope compositions of food sources and the metabolic processes of fatty acids of marine benthonic animals are both affected by environmental factors.Therefore, the environmental factors are the ultimate determinants of regional differences in stable isotope and fatty acid compositions of marine benthonic animals.