Should underwater pinnacles be used as thermal refugia or dive site?

Underwater pinnacles play similar roles as coral reefs such as nursery and feeding grounds, tourism sites etc. Many underwater pinnacles are found in the Gulf of Thailand and they have faced with coral bleaching, recorded in... [ view full abstract ]

Underwater pinnacles play similar roles as coral reefs such as nursery and feeding grounds, tourism sites etc. Many underwater pinnacles are found in the Gulf of Thailand and they have faced with coral bleaching, recorded in 1998 and 2010, resulting in coral reef degradation. In this study, we surveyed many underwater pinnacles in the Gulf of Thailand to assess their status and potential use for tourism. We found that some underwater pinnacles are thermal refugia for corals during the coral bleaching crisis. For example, the underwater pinnacles at Hin Phoeng which are located about 25 km offshore from Rayong Province, the Eastern Gulf of Thailand, and harbored high diversity of scleractinian corals, especially the susceptible corals to bleaching such as Pocillopora spp. and Acropora spp. Three morphs of Pocillopora spp. were recorded at the study sites. The most dominant type was Type B which had high population density (about 50 colonies.m^-2) in some areas. The surveys on coral communities at Ko Samet (about 27 km from Hin Phoeng) and Trat Province (about 90 km from Hin Phoeng) revealed that no colonies of Pocillopora spp. were observed during the study period. Therefore, the underwater pinnacles at Hin Phoeng should be reserved as a refugia for corals under the climate change crisis. However, many underwater pinnacles with less coral cover but having beautiful soft corals and sea fans may be promoted to be dive sites.