Abstract
Coral reefs are among the most biodiverse habitats on Earth, but knowledge of their associated marinemicrobiome remains limited. To increase the understanding of the coral reef ecosystem in the lower Gulf of Thailand, this study utilized 16S and 18S rRNA gene-based pyrosequencing to identify the prokaryotic and eukaryotic microbiota present in the reef water at Kham Island, Trat province, Thailand (N6.97 E100.86). The obtained result was then compared with the published microbiota from different coral reef water and marine sites. The coral reefs at Kham Island are of the fringe type. The reefs remain preserved and abundant. The community similarity indices (i.e., Lennon similarity index, Yue & Clayton similarity index) indicated that the prokaryotic composition of Kham was closely related to that of Kra, another fringing reef site in the lower Gulf of Thailand, followed by coral reef water microbiota at GS048b (Cooks Bay, Fr. Polynesia), Palmyra (Northern Line Islands, United States) and GS108b (Coccos Keeling, Australia), respectively. Additionally, the microbial eukaryotic populations at Kham was analyzed and compared with the available database at Kra. Both eukaryotic microbiota, in summer and winter seasons, were correlated. An abundance of Dinophysis acuminata was noted in the summer season, in accordance with its reported cause of diarrhoeatic shellfish outbreak in the summer season elsewhere. The slightly lower biodiversity in Kham than at Kra might reflect the partly habitat difference due to coastal anthropogenic activities and minor water circulation, as Kham locates close to the mainland and is surrounded by islands (e.g., Chang and Kut islands). The global marine microbiota comparison suggested relatively similar microbial structures among coral sites irrespective of geographical location, supporting the importance of coral-associated marine microbiomes, and Spearman’s correlation analysis between community membership and factors of shore distance and seawater temperature indicated potential correlation of these factors (p-values < 0.05) with Kham, Kra, and some other coral and coastal sites. Together, this study provided the second marine microbial database for the coral reef of the lower Gulf of Thailand, and a comparison of the coral-associated marine microbial diversity among global ocean sites.
Highlights
Marine microbiota differ by ocean geography, associated animals, seasons and human influences, and are found in all marine ecosystems, from the tropics to the Antarctic and Arctic, to deep hydrothermal vents (Kari, 2007)
The microbes help break down nutrients, produce metabolites that protect the corals from climate change, and secrete antibiotics that can protect the corals from some pathogens (Rohwer et al, 2002; Reshef et al, 2006; Dinsdale et al, 2008; Graham & Nash, 2013)
The Kham’s fringing reef seawater was clear and had no abnormal smell, and the coral condition was normal at times of sample collection
Summary
Marine microbiota differ by ocean geography, associated animals, seasons and human influences, and are found in all marine ecosystems, from the tropics to the Antarctic and Arctic, to deep hydrothermal vents (Kari, 2007). For a relatively identical habitats, differences in marine prokaryotic and eukaryotic populations at a small spatial scale can be due to human influences, such as from piers and residential housing (Hidayat et al, 2012; Somboonna et al, 2012). Coral reefs have one of the greatest diversities of organisms and microorganisms on Earth. They cover less than 1% of the Earth’s surface, they host approximately 25% of all marine species (Bryant et al, 1998; Spalding, Green & Ravilious, 2001), and intricate and complex relationships among corals and the surrounding microorganisms and animals occur. The microbial community could, impact coral health and ability to adapt to differing environmental conditions (Rohwer et al, 2002; Wegley et al, 2007; Barott et al, 2012)
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