Exposure at low tide leads to a different microbial abundance of intertidal coral Acropora pulchra

ABSTRACT Corals thrive in symbiotic relationships with a variety of microorganisms, including endosymbiont algae. The interaction between coral and microbial associations has been extensively researched since it is thought to play a function in coral health. Temperature and light are two abiotic elements that contribute to coral life. Corals in reef-flat environments frequently face variations in these two characteristics due to their proximity to shallow seas. This study aims to compare the microbial diversity and abundance associated with the coral Acropora pulchra on the reef flat under two conditions, namely corals that emerged to the surface at low tide (SF) and corals that submerged over time (SM) and to compare the microbial diversity of both with those found in its adjacent seawaters. Microbial analysis on 16S rRNA region V4 showed that the alpha diversity of coral microbial communities and seawaters was not significantly different. However, differences in abundance were noticed at the phylum and genus levels. With p-value < 0.05, PCoA analysis using the Bray–Curtis test showed that the coral microbial community was significantly different from the surrounding seawaters. This study indicates that under different conditions, corals of the same species can be dominated by different microbial groups. This study also confirms the uniqueness between coral microbes and their adjacent seawaters. The abundance of certain microbes is a host mechanism for survival.