The excavating sponge Cliona orientalis as a coral reef competitor’s on Krakatau Islands colonisation, Indonesia

The recovery of coral reefs on Krakatau Islands after the destructive eruption in 1883 has been reported in very limited study. Coral reefs began to grow on all islands in the Krakatau volcanic complex, including the highly active volcano island i.e. Anak Krakatau (north to west coast). Survival of coral reefs in the Krakatau Islands influenced by several factors such as predation, diseases, soft coral overgrowth, and also sediment covers. Somehow, sponges as one of killer-competitor of coral reefs have never been reported in the Krakatau Islands.