DNA-assisted inventory and community structure of benthic marine algae in Taiping Island (or Itu Aba Island), South China Sea

Abstract

Taiping Island (also known as Itu Aba Island) is located in the middle of one of the most politically controversial land strips in the South China Sea, thereby imposing a great obstacle for the exploration of marine biodiversity in this area. The goals of this study were to improve our knowledge gap of biodiversity of benthic marine algae (including both seaweeds and cyanobacteria) and to provide basic herbarium and molecular references on their communities. With 199 molecular sequences assisted for species identification, we found 19 orders, 40 families, 68 genera and 121 species in Taiping Island, including those belonging to 34 Chlorophyta species, 9 Ochrophyta species, 62 Rhodophyta species, and 16 cyanobacteria species. Among them, six genera, 14 species were new records for the South China Sea and more than 70% species were considered as new records for Taiping Island. There were also many taxa which may be considered as undescribed species new to science. In this fringing reef island, the species compositions were significantly different between two types of habitats separated by a reef crest. In the Reef Flat Zone, the most common species encountered included members of Caulerpa, Dictyota, Galaxaura and Halimeda. In the Reef Slope Zone, the most common species included members of Corallinales and Peyssonneliales. The nuisance coral-competing seaweeds (Galaxaura divaricata and Ramicrusta texitilis) and the cyanobacterium (Moorea bouillonii) were reported for the first time in Taiping Island. Our expanded DNA barcoding data in Taiping Island provides a greater understanding of the benthic marine algal biodiversity in the South China Sea.