Community Characteristics and Genetic Diversity of Macrobenthos in Haima Cold Seep

Abstract

Knowledge about community structure and genetic diversity can help assess the potential for change in the loss and restoration of biodiversity, thereby facilitating effective management and ecosystem protection. Macroinvertebrate communities are an important biotic component of deep sea cold seep ecosystems. As Haima cold seep is increasingly being assessed for its potential gas hydrate mineral wealth, knowledge of community characteristics and genetic diversity of macrobenthos is needed to anticipate the potential impacts on biodiversity. In this study, we examined species diversity and community structure at five sites in the Haima cold seep using a remote-operated vehicle (ROV) for in situ surveying. The results identified 12 macrobenthic species from 5 phyla and 12 families. The macrobenthos community could be divided into two communities (H1 and H2=mussel bed community, and H3 and H4= vesicomyid clams community) based on CLUSTER and NMDS analyses. Gigantidas haimaensis (Mollusca), Branchipolynoe pettiboneae (Annelida), and Histampica haimaensis (Echinodermata) were most dominant within their respective phyla, with values of the dominance of 0.160, 0.021 and 0.114, respectively. The genetic diversity of these three typical macrobenthic species in the Haima cold seep was evaluated using the mitochondrial cytochrome c oxidase subunit I (COI) gene, haplotype, and nucleotide diversity values were 0.651 to 0.912 and 0.00148 to 0.00812, respectively, representing high haplotype diversity but low nucleotide diversity. Finally, mitochondrial concatenated dataset (MCD) sequences from three mitochondrial genes (ATP6, COI, and NAD4) and 294,734 genome-wide single nucleotide polymorphisms (SNPs) from restriction site-associated DNA-sequencing (RAD-seq) data were obtained from 60 individuals from two sites (H1 and H2), providing deep insight into the genetic diversity and structure of G. haimaensis, the engineer species in Haima cold seep. No significant genetic differentiation between G. haimaensis in H1 and H2 was detected based on MCD sequences. Nevertheless, when using SNP datasets, a small but clear genetic subdivision between G. haimaensis in the two sites as revealed by STRUCTURE and principal component analysis (PCA). The results comprehensively illuminate macrobenthos biodiversity in the Haima cold seep ecosystem and provide a baseline against which population dynamics may be assessed in the future.