A study on the intertidal animal diversity of Xia-Sanheng Island by using morphological and DNA barcoding identification

Intertidal animals are an essential part of the ecosystem, and species diversity can reflect the state of the local ecological environment. However, traditional morphological identification is prone to corresponding classification errors or research limitations. With the development of molecular biology, many techniques and bioinformatics classification methods have been applied to identify species efficiently in recent years. This research aimed to examine the feasibility of DNA barcoding within the identification of intertidal animal species collected from the Xia-Sanheng Island. A total of 41 cox1 gene sequences were obtained by experimentalization or downloaded from the National Center for Biotechnology Information (NCBI) database. Then morphological classification, molecular identification, phylogenetic tree analysis, and Automatic Barcode Gap Discovery (ABGD) method were used to analyze the animal samples. We found that although the molecular classification of molluscs was not accurate enough, the collected specimens could be divided into 15 species, 12 families, and 4 phyla. Tetraclita japonica, Thais luteostoma, and Mytilus coruscus were the dominant species on the Xia-Sanheng Island. Additionally, there may be a new species, Platynereis sp., which needs further confirmation. We suggest that further identification of marine biodiversity should be carried out by combining morphological and molecular biological methods.