ILOILO City – The Bureau of Fisheries and Aquatic Resources (BFAR) has appealed for more technical experts and scuba divers to help remove destructive crown of thorns (COT) starfish that is infesting the waters of Culasi, Antique. One of the largest in the world, COT prey on hard or stony coral polyps.
A group of divers was supposed to conduct a COT cleanup on July 16 but the activity was postponed due to bad weather, said Director Remia Aparri of BFAR Region 6.
There is an outbreak of COT in Culasi, a first in Western Visayas, according to Aparri. The local government has declared a state of calamity.
Experts estimate that a COT can eat away about 10 square meters of corals per year. When there is an outbreak, however, COTs do not just eat “some” corals but they eat “a lot”.
“When there are no more corals, our fishes would no longer have habitat,” said Aparri.
For his part, Dr. Jon Altamirano from the Southeast Asian Fisheries Development Center in Tigbauan, Iloilo, said COT “naturally exists in coral reefs and their presence alone cannot be considered as an outbreak.”
But when there is an outbreak, he said, COT “eat so fast that the corals cannot even recover. So, a massive outbreak can cause a major impact on coral reefs.”
From June 25 to 29, a team from BFAR conducted a reef assessment in Culasi. There were between five to 10 COT per square meter.
“There is an outbreak when there are more than 15 COT per hectare,” said Aparri.
The BFAR technical team was able to gather a total of 426 COT.
“But there is still a large number of COT that must be extracted,” said Aparri.
The sudden increase in COT population could be due to the “abundance of food, not for the adult COT but for the planktonic larvae, even before they settled in Culasi,” said Altamirano.
“When the larvae become well-developed, they need appropriate conditions before they settle on corals as ‘babies’ and grow to adults. Appropriate conditions for settlement mainly involve a proper substrate with good food. For COT, this means areas with good corals, which are their primary food. So, Culasi may have been the best place for the planktonic larvae to settle. It has abundant and healthy corals,” he said.
Aparri said the COT is characterized by numerous spines projecting from its body wall. It has a large central disk and has around seven to 23 arms.
The most practical way is to manually remove the COT but divers must do it with utmost care, said Altamirano.
“The safety of divers is most important. COT thorns can cause severe pain and swelling,” he said.
The integrity of the corals must also be maintained, Altamirano added.
Citing sciencedaily.com, Christopher Salao of Basecamp Divers in Panay said the problem is not unique to Culasi. The predator starfish are in fact decimating large tracts of coral reefs throughout the country. He said an individual can consume up to six square meters of living reef per year.
The outbreak in Culasi could be due to the increase in water temperature or nutrient levels, said Salao.
Some of the starfish’s major predators such as the humphead wrasse and giant triton, which usually keep the species in check, have declined in recent years as a result of overfishing, he added.
When their group visited Culasi last year, Salao said, the COT population was already “beyond normal.”
“Just imagine the corals na posible ma-wipe out. Affected gid ang mga isda,” Salao said./PN
