The seawater was continuously pumped from the reef near the research station and was supplied to the tank without filtration. One month before the start of the experiment (April 2012), 48 coral fragments were prepared by cutting branches of the 3 coral colonies with a plier (16 fragments from each colony). The fragments were attached on polycarbonate bolts (1 cm wide, 2.5 cm long) with acrylate adhesive and were again maintained in the outdoor tank until coral tissue started to cover the exposed skeleton.