The Research On DNA Barcode Of Fish Eggs And Adult Fish In Some Island In The South China Sea

The Xisha,Zhongsha and Nansha Islands in the South China Sea are mostly coral reefs composed of reef-building corals.They are a special kind of ecosystem in the ocean and contain abundant fish resources.Correct understanding of fish is a prerequisite for the conservation and development of fish stocks.The rise of DNA barcode technology provides a fast and efficient method for fish identification.The establishment of a complete database of DNA barcodes provides strong support for the promotion of DNA barcodes.This study explored the applicability of DNA barcodes in the Siganidae and the parrotfish,and identified the eggs of the four island reefs of Meiji Reef,Zhubi Reef,Chenhang Island and Qilianyu.This work has greatly improved the DNA barcode data of Coral Reef Fish from South China Sea.The results are as follows:1.We obtained 46 CO Ⅰ genes from 10 species and downloaded 27 CO Ⅰ genes from 12 species from BOLD and GenBank to study the CO Ⅰ gene’s genetic composition,intraspecific and interspecific genetic distance,codon characteristics and molecular phylogenetic tree.The results show that the average base composition of 73 CO Ⅰ genes was T:28.8%,C:28.8%,A:24.7%and G:17.8%.The content of G+C(46.6%)was lower than the content of A+T(53.5%)and the base composition showed obvious bias.The average interspecific genetic distance was 0.098,which was 49 times the length of the genetic distance within the species(average:0.002).The phylogenetic tree reveals that Siganus unimaculatus and S.vulpinus clustered into one branch among 19 species of basket fish.The other 17 species(89.5%)clustered in monophyletic groups at genus level.It is shown that the technology of DNA barcoding can be used for fish species identification of Siganidae.2.We investigated the performance of DNA barcodes in a sample of Scaridae.A total of 401 DNA barcodes using 533 base-pair fragments of the cytochrome c oxidase subunitⅠ(CO Ⅰ)gene were generated.350 of the CO Ⅰ barcode clusters represented 43 species submitted to the Barcode of Life Data Systems(BOLD)and GenBank databases.The mean nucleotide compositions for the complete data set were as follows:29.5%adenine(A),29.5%thymine(T),29.5%cytosine(C)and 18.2%guanine(G)in the order C=T>A>G.The mean genetic distance between confamilial species was nearly 53-fold higher than that among individuals within species.In the Neighbor-joining tree of CO Ⅰsequences,C.sordidus and C.spilurus clustered together,all of the individuals of the other same species clustered together.Our results supported DNA barcoding as an efficient molecular tool for achieving better monitoring,conservation,and management of fisheries.3.In this study,3045 fish eggs samples from Meiji Reef,Qibi Reef,Qihang Island and Qilianyu were collected for photos and DNA extraction.Using DNA barcode technology,1150 fish egg sequences were obtained by sequencing;1039 fish eggs were accurately identified,of which 83 were identified as genus and 956 were identified as species,belonging to 12 orders,40 families,84 genera and 162 species.412 fish eggs were identified in Chenhang Island,of which 381 were identified as species and 31 were identified as genus.There were 15 species of fish collected in spring and autumn.69 species of Meiji reef fish eggs were identified,of which 65 were identified as species and 4 were identified as genus;3 species of fish eggs were collected in at least 2 seasons in spring,autumn and winter.431 fish eggs were identified in Qilianyu,of which 403 were identified as species and 28 were identified as genus.There were 15 species of fish eggs collected in at least 2 seasons in spring,summer and autumn.127 fish eggs were identified in Zhubi Reef,of which 107 were identified as species and 20 were identified as genus.One species of fish eggs was collected in spring and autumn:Scolopsis monogramma.The islands with the highest species similarity among different islands are Qilianyu and Chenhang.The results showed that direct cryopreservation is more beneficial to the preservation of morphological characteristics of fish eggs.At the same time,DNA barcode technology can be used as an effective way to identify fish eggs.In the absence of obvious fish egg morphology identification,it can effectively compensate for the insufficiency of classical morphology.At the same time,the morphological characteristics database of fish eggs is in turn filled.