Diversity and Abundance of Non-Geniculate Coralline Algae (NGCA) in Different Reef Conditions and Depth Zones

Abstract

Non-g eniculate coralline red algae (NGCA) provide habitats for many epiphytic fauna and flora, and are considered reef engineers. The identification of NGCA is challenging due to cryptic speciation and their phenotypic plasticity that can be mediated by environmental conditions. Using DNA sequence data (psbA gene), a systematic examination was undertaken of the diversity and abundance of NGCA from two different reef conditions (fair and poor reef) and depth zones (shallow and deep zone) of a subtidal reef in the Gulf of Thailand at Koh Taen, Surat Thani Province, Thailand. Phylogentic analysis revealed 11 putative species: Chamberlainium sp., Dawsoniolithon sp., Hydrolithon boergesenii, Lithophyllum sp.1, Lithophyllum sp.2, Neogoniolithon sp.1, Neogoniolithon sp.2, Parvicellularium sp., Sporolithon ptychoides, Sporolithon sp.1 and Sporolithon sp.2. Specimens attributed to a newly recorded genus Parvicellularium, showed its highest abundance in the deep zone, while specimens attributed to Lithophyllum and Sporolithon were dominant in the shallow zone. The abundance of all NGCA genera showed no significant differences among reef conditions. Here, we present an updated overview of the diversity and abundance of NGCA in Thai waters.