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A fully grown COTS (left) sits on a huge coral while consuming its top.

Outbreak of fiercely destructive starfish in coral reefs of Mambulao Bay

CROWN-OF-THORN STARFISH PANDEMIC

 

Fishermen are waging a fierce war against highly invasive and predatory starfish species that have been destroying coral reefs in the town's coastline

By ALFREDO P HERNANDEZ

EARLY last month, a group of fishermen-volunteers began diving double-time to uproot a fiercely destructive starfish species, the crown-of-thorns starfish — that has invaded a wide area of coral reefs along the coastlines of Mambulao, Camarines Norte.

And in its wake, it destroyed in silence coral reefs at a scale never seen before in the municipality.

The fishermen said they had never encountered it in so great a number over the past ten years of their fishing.

They were unaware of it, maybe because during those times they were just tiny dots scattered across a wide area of coral reefs in Mambulao Bay that faces the Pacific Ocean.

But not anymore.

Over the past 12 months, spear-fish hunters had observed an odd-looking, spine-wrapped sea creature that had invaded the reefs and destroying them in silence.

Worse, its path was littered with fragments of coral that were leftovers from what the predator had gobbled up.

According to the Bureau of Fisheries and Aquatic Resources (BFAR), the crown-of-thorns starfish or COTS sits on top of the coral and begins chewing it up.

In the next 24 hours, a COTS six inches in diameter could munch corals as big as a square foot.

Memories

In the 1960s when I was a teen, I used to spearfish, crabs, and shrimps in coral reefs near our beach in Parang, Mambulao, at low tide.

My home was just 700 meters away from Parang Beach, the beach of my youth.

I would see the common starfish under shallow, clear water painstakingly crawling across the sand on its way to a hiding place under a rock.

I would also see sea urchins, those spiny dark brown balls that would cross my path.

But never did I see a COTS.

This predator-invader never existed in our bay waters, one reason our coral reefs in those days in the 1960s were vibrant, healthy, thick, and in living color.

They were home to many fish species, crabs, and bivalve shells that made fishermen happy for the bountiful catch they would bring to the local market after their overnight fishing expeditions.

However, without us being aware of this, the COTS pandemic began in 1962 in the many reefs that made up the Great Barrier Reefs in Australia.

It had spread naturally on reefs across the Indo-Pacific region, including the Philippines, and when conditions were right, they plagued proportions and devastated hard coral communities.

It is only these days–60 years after it was first detected in the Australian Great Barrier Reefs — that the COTS pandemic is being felt in the waters of Mambulao Bay.

COTS has invaded the coral reefs here.

Two volunteer divers extract COTS from its lair.

Grim scenario

BFAR revealed a grim scenario: that if there are about 30 COTS in a hectare of the coral sea, there’s already an outbreak.

Over the past three weeks, the Mambulao volunteer-divers had extracted about 10,000 COTS from six to eight coral reef areas.

And they are counting for more each time they return to the waters to hunt them.

With no letup, the 12 volunteers uprooted and hauled up the troublemakers to the surface of the bay water from eight feet deep at a rate of 200 heads in less than 30 minutes.

Overfishing

Decades’ old studies have revealed that overfishing of the COTS’ primary predator, the giant triton, was the biggest culprit that spurred the spread of COTS.

It is a very large marine snail that can reach sizes of one and a half feet long.

The giant triton is an active predator and chases aggressively its prey, which it detects with its excellent sense of smell.

Though the chase may seem slow to human observers, the giant triton is relatively fast, especially for a snail. It prefers to eat other snails and sea stars, most notably the crown-of-thorns starfish.

Nowadays, the giant triton is almost extinct after it was over-fished for its high value as an expensive, rare home ornament.

COTS is highly venomous as its spines contain neurotoxins and other starfish poison that are dangerous to both humans and marine creatures.

The venom of COTS could cause severe pain, itching, and swelling.

In the Mambulao operations, the divers are using pairs of thongs (pansipit) to hold COTS in place and to extract it from the coral reef it had clang to.

But they are looking at using an injection gun to jab some chemicals into the arm of COTS to paralyze and kill it overnight.

But since one injection gun costs at least P3,000, the prospect of using it could take some more time, as the teams have to wait for donors’ help.

For a starfish, COTS moves fast – 20 meters an hour, and each night, it can eat its body area in coral and it grows up to a meter in diameter. COTS also goes after deeper, slow-growing corals such as the reef-building species, Porites.

Unlike the typical starfish with five arms, the COTS is disc-shaped with multiple arms (up to 21) covered in poisonous spines.

Right now, the Mambulao volunteers are working hard to dispose of the COTS.

The first option for them was to dry the COTS haul, but it emits a toxic odor as it dries up.

So burying it in the ground meters away from the shore has been the best option to deal with it.

The divers led by Artemio Andaya look across a wide spread of extracted COTS which later were buried under the sand. So far, the team has neutralized over one thousand starfishes since it began the initiative early July.

Right now, the volunteers comprising two teams of six men each are seeking financial and material aids to sustain their daily operations.

So far, the anti-COTS drive gets support from prominent families in Mambulao, and those natives based abroad.

They needed fuel for their two bancas, food, and basic diving gear to reach COTS and extract it from the reefs it has clung to.

(For financial help, donors could contact the volunteers through its Facebook account: https://www.facebook.com/mambulao.artsncrafts .)

(This article first appeared in OpinYon.net:

https://opinyon.net/national/outbreak-of-fiercely-destructive-starfish-in-coral-reefs-of-mambulao-town-in-camarines-norte