By Minerva Newman
CEBU CITY—A group of scuba divers, volunteers and members of the Knight Stewards of the Sea, Inc. (Seaknights 2.0) fear of a possible Crown of Thorns (COT) starfish outbreak in Bogo Shoal, a marine sanctuary with an estimated area of about three hectares that is part of the 24-hectare Lagundi Reef off the coastal waters of Talisay City in Cebu.
Seaknight 2.0 marine biologist William Villaver, in his Facebook post, described it as a case of “SPOT COT outbreak” since COT collected were concentrated in the eastern side of the reef where there were already plenty of corals being eaten by the starfish.
Villaver said it could also be an incipient outbreak which is equivalent to an upcoming outbreak since there were 19 small juvenile COTs among the fully-grown COT’s that they collected last Sunday, December 22.
“Active total COT outbreak should be acted upon ASAP since during these situations, one square meter of coral in the reef is consumed by the COT every day,” Villaver noted.
According to Ed Karlon Rama, one of the volunteer-divers, who is also a member of Seaknights 2.0, the group has been able to remove 65 pieces of the coral-eating starfish, including 19 juveniles, in a span of approximately 30 minutes at a 50-meter patch of the Bogo Shoal.
Villaver described it as a possible outbreak because there should only be 30 COT starfishes for every hectare of healthy coral reefs.
The crown of thrones (COT) are coral-eating starfish that are endemic to tropical waters, Rama added that they increase their population because of the presence of more nitrates, including detergents dumped into the seawaters, and over fishing of its only natural predator, the giant triton seashells.
“We first noticed the outbreak in Bogo shoal last Sunday but, in previous dives, we’ve already noticed their presence. In previous dives, we’d turned them upside down and buried them in the sand. This suffocates them and kills them. Then the reef fishes will eat them after they decompose,” Rama explained.
Rama told The Manila Bulletin that in the group’s dive on December 22, they already saw the COT starfishes in piles very close to the coral nursery in Bogo Shoal. The coral nursery is part of the reef that got destroyed years ago when a ship ran aground here, and we are trying to rehabilitate that part by planting corals.
“We got very concerned because they might attack the replanted coral fragments. We knew we could not let them be because they can cover 20-meters an hour crawling at night and we could not just turn them upside down and burry them because it takes too much time to that. But we just have to cull them to manage the numbers,” Rama added.
Rama explained that COTs cannot be killed by just stabbing them because they will just stress-spawn and split into millions of gametes before dying. “They must be manually removed as many as possible before the air in our tanks ran out, put them on sacks, turning them belly-up and bury them in the sand,” he said.
According to Villaver removing the mature COTs must be dealt with utmost care because rough handling them may trigger them to release gametes, these are fertilized eggs to ensure their survival of the new set of young COTs spreading all over the area.
Rama said that they collected 65 pieces of COTs including those 19 juveniles that they buried in the sand to suffocate them until they die. Then the reef creatures eat them as part of natural decomposition.
“But, as you can see, it is time consuming to do this. This won’t work in an outbreak,” Rama said.
Rama added that they concentrated at the Bogo Shoal because of the nursery. The COTs can wipe out the entire nursery because the corals there are still young, and years of work would just go down the drain.
But they can’t stop there, Rama said, because the other patches of reef already had COT infestation, and there are corals that are centuries old, very old corals that will be consumed if the outbreak is not stopped.
The group is diving again on Friday, December 27 with scheduled two dives each for the next four Sundays to continue the cleanup. “But there are only six of us doing it,” Rama said.
The group is calling the Bureau of Fisheries and Aquatic Resources (BFAR-7) to assist them and validate the situation to prevent an impending COT outbreak in the area.