By: Emme Rose Santiagudo
THE Bureau of Fisheries and Aquatic Resources (BFAR) in the region called on professional scuba divers to respond to the outbreak of coral-eating seastars in Culasi, Antique.
BFAR Regional Director Remia Aparri sought the help of professional divers following the outbreak of the sea pest, crown-on-thorns (COTs) in Culasi, Antique.
According to Aparri, the local government already placed the town under a state of calamity on June 11, 2019.
“The local government in Culasi sought our help to respond to the COTs outbreak in their area,” she said in a phone interview on Friday.
In Maniguin Island in Culasi, 10 to 15 COTs per square kilometre were spotted, according to Aparri.
“An outbreak can be declared if there more than 15 COTs per hectare. In their case, there is already an outbreak on the COTs because their population is beyond normal,” she said.
The regional director expressed her alarm over the COT outbreak in Culasi especially because of the threat that it can pose to coral reefs.
“Sobra ka delikado because ang ginakaon nila corals. They prey on live corals and if wala na coral, wala naman isda and wala naman pagkaon,” she lamented.
While there are sightings of COTs in Guimaras, Aparri said the outbreak in Culasi was the first to be recorded in the region.
COTs are large seastars that prey on coral reefs and can consume up to six square meters of living coral reef in a year.
Dr. Jon Altamirano of the Southeast Asian Fisheries Development Center/Aquaculture Department (SEAFDEC/AQD), explained that the presence of COT actually indicates a healthy reef however an outbreak can cause a massive impact to the coral reefs.
“COT naturally exists in coral reefs and their presence alone cannot be considered as an outbreak, COT indicates a healthy reef. A few of them helps keep the reef healthy by eating away ‘some’ corals that can eventually recover. However, when there is an outbreak, COT do not just eat ‘some’ corals but they eat ‘a lot!’ And they eat so fast that the coral cannot even recover. So, a massive outbreak can cause a major impact on the coral reefs,” he said.
Altamirano’s theory on the sudden increase of COT in Culasi relates to the probable abundance of food which are also flowing in the same water column as the COT larvae.
“Maybe it relates to the food not for the adults, but food for the plantonic larvae even before they settled in Culasi. Rains during the past weeks may have introduced a lot of nutrients to the coastal waters (not only in Culasi but neighboring areas as well), aiding in the abundance of micro-algae. More micro-algae caused a lot more of the COT larvae to survive and develop very fast. Then, when those unnaturally abundant COT larvae passed by Culasi, a whole lot of them settled causing the ‘outbreak’,” he explained.
On the other hand, the outbreak can also be caused by the lack of predators that prey on COT mainly because of overfishing, according to Aparri.
“Ang predators nga nagakaon diri sa COT nubo na ang population. Because of overfishing, ang mga fishes nga gakaon sa ila wala na dira,” she said.
Meanwhile, Aparri said they immediately responded to the outbreak upon the request of the local goverment of Culasi.
From June 25 to June 29, 2019, Aparri said they conduct reef assessment and COT extraction in Culasi in coordination with the local government.
“We conducted and coordinated with LGUs and deployed scuba divers from June 25 to 29 to conduct reef assessment and to manually extract the COT,” she said.
Aparri added that they were able to collect 500 COTs in the first two dives of the volunteers.
However, she appealed for more professional divers to volunteer and join the collection of COT as there is still an impending outbreak in the area.
Recently, a group of Iloilo based divers, Basecamp Divers also collected around 500 COTs in the nearby island of Culasi, the famous Mararison Island.
Christopher Salao, member of the group has reminded that only professional divers or those that were properly oriented can do the manual extraction since the COTs are extremely sensitive.
Once agitated, Salao said one COT can release 100 to 1000 eggs and worsen the outbreak.
As a short term solution, Altamirano advised that COTs must be culled if observed to be too many in an area.
The most practical way is manual removal by divers. But utmost care is needed for this method,” he said.
In the long run, he emphasized that proper management on land is vital since land-based activities cause a great deal of effect to the seas.
He also underscored that the safety of divers must be prioritized at all times.
“COT thorns can cause severe pain and swelling when stung, so some implements may be needed. Integrity of the corals needs to also be maintained, so taking care of the corals during the process must be observed,” he said.