Chinese Offshore Zooplankton Species Information Platform And Primary Application

Zooplankton is the most important component in material exchange and energy transfer process of marine ecosystem. It is joint of the marine food web, transporting nutrient and energy from lower trophic level to higher trophic level. The succession and quantitative changes of species can affect the whole marine ecosystem. The identification of zooplankton is the technical base of diversity and distribution of zooplankton, so it is very important to study of marine ecosystem. Traditional identifying method is examining specimen under microscope, requiring fine skill of trained identifier and time consuming. The larva may not be identified by the traditional method. Thus, promoting the identificating methods to enhance precision and reduce the consuming time of identification, is very important.Combining the traditional identifying methods and molecular biological technique, this study constructed the foundation of Chinese Offshore Zooplankton Species Information Platform. The platform of Chinese Zooplankton information, containing monophyly information, the images of the specimen, and the DNA barcoding sequence information, was builded by the study through standard technique for gathering images of zooplankton and their sequence. The Chinese Offshore Zooplankton Species Image Database of the platform improved communication of traditional zooplankton identifing information. The DNA barcoding Sequence Database of the platform promoted the metagenomic methods of biodiversity study based on the DNA barcoding technique. In all, the platform would improve the identification based on the morphological and DNA barcoding. The library of offshore zooplankton images of China of this platform contained1086images. These pictures belonged to246species,135genus,68families,26orders, and7phylum. Based on the analyses of DNA barcodes, mtCOI sequences of various zooplanktonic species were revised. These species belong to genus Acartia, Pleuromamma, and family Eucalanidae (as Chen Qingchao’literature in1965). Acartia negligens from the same location of the South China Sea, Subeucalanus pileatus and Pleuromamma borealis from different oceans, Pleuromamma xiphis and Rhincalanus nasutus from East China Sea and from the offshore of Japan, fell into different branchs of NJ tree, which meant they have high intraspecific genetic divergence at large geographical scale.Based on the available zooplankton barcode database, an environmental DNA barcode library was constructed to study zooplankton composition in Jiaozhou Bay and the Changjiang estuary. In Jiaozhou Bay, A total of149mtCOI sequences were determined from the coxl gene secquences library. K2P genetic distances between individuals within the same species ranged from0to0.11, with an average of0.013(SE=0.003); meanwhile, genetic distance between species within the same genera ranged from0.137to0.369, with an average of0.265(SE=0.002). Thus the average of genetic distance between species was at least20times larger than that within species, indicating a barcode gap which ensured that mtCOI sequences can be used as reliable characters for species identification for the zooplankton assemblages. The genetic divergence of6%was adopted,37OTUs (species) was estimated. The results of BLAST of the OTUs were compared with the morphology identification work on species richness of sample from the same location of Jiaozhou Bay.The validity of the study method was assured.In Yangzi Estuary, a total of856mitochondrial coxl gene sequences from4samples of different location were determined from the coxl gene library. The occurrence of70OTUs (species) was estimated when the genetic divergence of5%was adopted as the threshold to separate different species. The monophyly of all the species was also resolved. The results of BLAST of the OTUs were compared with the morphological study on species richness of Changjiang Estuary. The nonholozooplanktonic species identified by the DNA barcodes here were supposed to be sampled with the dispersal life history phase.The result was basically consistent with the result indentified by Morphology characters. The DNA barcoding method was better in identifying sibling species. With comprehensive database, fast estimation of zooplankton richness can be performed by the environmental DNA barcoding approach.