A case study of infestation of Acanthaster pianci in Andaman waters

Abstract

The starfish feeds on coral polyps and often plague of them are observed on many parts of the Indo – Pacific reefs causing mortality to vast areas of reef corals and their subsequent degradation. The species exhibits a wide range of colour patterns in nature, the common being violet with purplish or blue streaks on the middle of the arms or rusty brown or may be blue. A. planci is widely distributed in the Indo-Pacific from the east coast of East Africa, Red Sea, and then eastward as far as Hawaii. Acanthaster planci was observed at Grub Island, Chester Island, Alexandra Island, Red Skin Island and Twin Islands*.The reefs of Andaman surveyed are dominated by either Acropora spp. or massive Porites in different parts. The maximum concentration of Acanthaster was observed in Grub Island, nearly 50 m away from shore, in shallow waters. The mass mortality of corals observed at sites in the National Marine Park cannot be attributed to predation by Acanthaster. In deeper waters also mass mortality to corals was observed which might be due to many natural causes. Predation by Acanthaster might have played some role in the death of corals but this is not of an alarming state at present.