Five Decades Behind the Limelight: Crown-Of-Thorns Sea Star Outbreaks Razing the Already Ailing Philippine Reefs

Abstract

A massive decline in Hard Coral Cover has been observed in the Philippines over the past decades, and Crown-of-thorns Sea star (COTS) outbreaks contribute to this decline. Effectively managing these outbreaks will aid in conserving the country’s reefs. However, questions about the extent of the damage caused by outbreaks, the biology of the Philippine COTS, and the nature and triggers of outbreaks dramatically limit the development of effective management. This review presents the existing knowledge of the biology of the Philippine COTS, past and present COTS outbreaks in the country, and current management strategies used to control these outbreaks. An extensive literature search was done to consolidate historical reports of COTS outbreaks from published journal articles, news articles, and personal communication with government agencies and other organizations. Results showed that COTS was reported in the Philippines as early as 1938, but outbreaks have been documented for the past five decades. COTS outbreaks have been consistently reported in the waters of Cebu, Central Visayas from 2002 to 2008 and 2018 to 2021. COTS spawning in the Philippines was reported during the summer months from March to May, but further studies are needed on other aspects of its biology, especially on its morphology, reproductive capacity, larval biology, and feeding capacity. Lastly, a Philippine COTS management program involving the government, the academe, and citizen scientists is urgently needed to monitor COTS outbreaks and minimize its effects on the country’s ailing reefs.