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Apo Reef Spared from Predator Starfish

16/05/2006 00:00:00 WWF-Philippines Organizes Successful Clean-up Operations

5212 Crown-of-Thorns Starfish (COTS for short) were collected in separate cleanups in the vicinity of Apo Reef in Sablayan as part of a nationwide summer drive by WWF, and others to curb COTS infestations in Philippine reefs. The Crown-of-Thorns Starfish (Acanthaster planci) is a large, robust and voracious echinoderm that feeds almost exclusively on the tissue of living coral.
An adult Crown-of-Thorns Starfish, a top coral predator, is collected off a reef in Batangas. (WWF-Philippines / RAF SENGA)
Found throughout the Indo-Pacific region, COTS populations swell each summer. Adults are simply ravenous, eating large amounts of important coral species, usually from the genus Acropora (the branched corals most commonly associated with reefs). Massive swathes of the world’s coral reefs have been destroyed since global COTS populations started booming in the 1970s. Outbreaks can reach plague proportions: tens of thousands of individuals can suddenly appear in a few weeks. Just one adult can consume six square meters of reef annually.

12 to 20 arms ring a green to tan central disc that measures up to 40cm, though giant specimens – some as large as 80cm, have been recorded. Its sheer bulk, coupled with a dense coat of stinging spines up to 5cm long – prove an effective deterrent against most predators. Natural predation falls mostly to the Napoleon Wrasse, Harlequin Shrimp and Giant Triton. However, global fish stocks have been over-harvested since the 1950s – where the World Fish Center estimates that as much as 90% of the world’s fish stocks have been consumed. Hence, the lack of COTS predators.
A Giant Trumpet Triton shell attacking a Crown-of-Thorns. © Cat Holloway/Canon - WWF
The first COTS clean-up were carried out in January, where diver-volunteers collected 704 of the spiny predators. A second effort followed in February, yielding a further 387. To enhance operations, fishermen who were being allowed to fish within the protected areas (using sustainable methods) were requested to assist. They collected 1332. Even local octopus hunters, skilled in tracking and capturing their eight-legged quarry, joined the fray – garnering a respectable 1300. Club Paradise Resort from Busuanga, Northern Palawan, also helped collect 420 of the creatures.

The last cleanup was held this month and included representatives from DENR-PAO, the LGU of Sablayan and volunteer fishermen. 1059 were gathered. Though destroying large numbers of starfish may initially sound inhumane, WWF recognizes the need to reset nature’s balance. Says WWF CEO Lory Tan, ‘In cases where you have relatively young or recovering reefs, we choose to control COTS populations because most Philippine reefs are generally not in very good shape. They need the opportunity to recover. Plus, close to 50% of Filipinos living along our coastlines depend on seafood and many reef species as their sources of food.’ Thus the physical removal of the COTS is the only practical way to spare our reefs damage. By season’s end, 5212 have been collected in Apo Reef alone.

Balance of nature
Raf Senga, WWF Asia Pacific Energy Policy Coordinator and a cleanup participant says, ‘Make no mistake, Crown-of-Thorns Starfish play an important ecological role – they help keep fast-growing coral species in check, preventing them from dominating slow-growing, but equally important coral species. However, a host of reasons have upset nature’s balance – not the least of which is increasing global temperatures brought about by climate change.’

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