2. Methods
2.1. Coral collection and preparation
The experiment was conducted at Sesoko Research Station (Tropical Biosphere Research Center, University of the Ryukyus) at Sesoko Island (26°37′–39′N, 127°51′–52′E), Okinawa (Japan), which is located in the subtropical climate zone. Three coral colonies of Acropora tenuis (colonies A, B, and C) were collected ca. 50 m off from the coast of the island, where the depth was 1.5 m at low tide. Within 30 min of collection, the corals were transferred to the research station and maintained in an outdoor flow-through tank under natural sunlight conditions for several months before the experiment.