An outbreak of crown-of-thorn starfish (COTS) in northern Palawan’s coral reefs has alarmed local authorities, who are also pushing for measures to mitigate their spread.
Board member Nieves Rosento said COTS infestations have so far been reported in El Nido, Linapacan, Taytay, Dumaran Island, and Araceli.
“In Linapacan, almost 1,800 yung nakolekta nung local divers. And then yung El Nido, total na recorded 65,209 collected, based on Malampaya Foundation data,” Rosento said.
Volunteers from the local government in El Nido have been trying to contain the COT outbreak in their municipality since 2009, according to Rosento.
She further mentioned that among the 65,209 crown-of-thorn starfish that have been gathered from El Nido in that time span, a recent collection accounted for 3,577 of them.
“This phenomenon has placed under threat the corals of Palawan. There are signs that this is worsening,” Rosento said.
She noted that research and volunteer efforts to control the crown-of-thorn starfish infestation require funding, and that locals would make their own improvised equipment for collection.
“Base po sa experience natin sa El Nido, umaabot ng P25,000-28,000 ang cost ng process ng collection. Hindi binabanggit yung bayad sa mga divers kasi mga volunteers [sila]. Normally, it’s just for the fuel, the food, the vinegars, at yung air tanks ay nililibre na ng mga divers ng El Nido,” she said.
The volunteers use improvised equipment: syringes loaded with vinegar. They then dive to the reefs to inject the vinegar solution into the mouths of the COTs, causing them to let go of the corals.
Rosento explained that injecting the COTs with acids like vinegar, or using their own stomach acid, is an effective way to kill the starfish, as they cannot be manually removed from the corals due to their highly venomous spikes. The divers use tongs and other tools to pick up the COTs and bury them far from the shore so that the starfish will not release any of their toxic spikes underwater.
The infestation of COTS can be attributed to their reproductive cycle. Unlike most starfish, which regenerate entire bodies from a single limb, the COTS reproduce through broadcast spawning, which involves freely releasing eggs and sperm into the water. These reproductive elements are then fertilized wherever the waves carry them.
“COTS mature into adults within two to three years, with the capability to spawn between 60 and 100 million eggs,” Rosento pointed out.
Rosento pushed for a resolution to grant funding and equipment to volunteers, while also urging local government units to closely monitor their reefs. This effort aims to supplement the current data and prevent further infections among the northern coral reefs.
She also advocated for the introduction of COTS natural predators into the affected areas, specifically the giant triton snail, crabs, lobsters, and other bottom-dwelling fish.
However, she said this is only a temporary solution so that the COTS do not reach maturity level.