Does the Zhenbei seamount in the South China Sea harbor distinctive biodiversity? A primary study based on eDNA metabarcoding

Abstract

The South China Sea is one of the regions with the richest marine biodiversity in the world, featuring a variety of ecological environment such as deep-sea plains, seamounts, and cold springs. Currently, studies on the biodiversity of the South China Sea seamounts are relatively limited, and the seamount effect is still debated. In this study, we used environmental DNA metabarcoding to analyze data from three biological communities in the Zhenbei seamount. We studied the biodiversity and environmental factors in this area and compared the data with those of deep-sea plains and cold spring areas to analyze the biological uniqueness and seamounts diversity. A total of 158 species of phytoplankton, 147 invertebrates, and 82 fish species were identified in the area. The abundance of invertebrates and fish in the Zhenbei seamount was high, with invertebrates showing obvious spatial differences, while the distribution of fish communities exhibited stability. However, phytoplankton community richness was quite low and declined exponentially with depth, attributed to seamounts disturbing the direction and speed of ocean currents, resulting in local eddies and upwelling that changed nutrient availability at different depths. The composition of biological communities in the deep-water area also verifies this view. Our work highlighted the impact of the Zhenbei seamount on community diversity, supporting the long-standing hypothesis that the seamount is a hotspot for species diversity, and provided technical support and knowledge for further exploitation and biodiversity conservation of the seamount.