A fresh batch of 40 true giant clams (Tridacna gigas), which were reared at laboratories in Bolinao, Pangasinan, were recently planted off Hamilo Coast in Nasugbu, Batangas, the World Wide Fund for Nature-Philippines (WWF-Philippines) reported yesterday.
The 40 giant clams, locally known as taklobos, were placed in their new homes on Santelmo Reef on May 28. In November last year, 102 giant clams were planted in the same coast. WWF-Philippine said an additional 35 giant clams are still underway, which would bring Hamilo Coast’s giant clam population to at least 170 soon.
“It’s amazing how fast Santelmo’s fauna has returned. Corals, invertebrates, and even large reef fish are being seen more frequently,” said WWF-Philippines project manager Paolo Pagaduan.
“It is hoped that baby clam recruits will eventually appear to seed outlying areas in Batangas,” he added.
Santelmo Reef is Hamilo Coast’s prized snorkeling site, the international conservation group noted. An area once blasted by dynamite fishers, the group said that Hamilo Coast has long since taken to “regrowth” with the assistance of the WWF.
Now, the group also said, new heads of Acropora and Pocillopora corals sprout alongside giant Porites boulders encrusted with legions of Christmas tree worms in Hamilo Coast.
According to WWF-Philippines, the True Giant Clam, as described by Linnaeus in 1758, is the world’s largest bivalve mollusk. It is the most massive of the seven known giant clam species and occurs in shallow waters of the Pacific and Indian Oceans.
The WWF-Philippines said mature individuals, which can live for over a century, have been known to exceed 1.4 meters in length and weigh in at over 260 kilograms.
Apart from the giant clams, the other large clams present in Hamilo Coast are Tridacna squamosa and Tridacna crocea.
“Resembling pouty lips, colorful clam mantles provide homes for symbiotic dinoflagellate algae called zooxanthellae, which provide clams with food and give them their color. For this reason, giant clams can only survive in shallow, well-lit areas,” the WWF-Philippines said.
An assessment of Hamilo Coast’s initially seeded clams revealed that mantle coloration has considerably improved, Pagaduan noted.
“When we planted the first batch last November, all clam mantles were pale gold. Now, each clam displays vibrant electric hues of blue and violet indicating that the area is conducive to clam growth,” he said.
The WWF-Philippines said giant clams are an integral part of the reef because they serve as nurseries for a host of fish and invertebrate species such as damsels, gobies and tiny commensal crustaceans like shrimp.
It also said that sedentary organisms like sponges, tunicates, corals and algae find giant clamshells perfect substrates for attachment, as most mature giant clams are partially encrusted by other reef organisms.
Moreover, the group said giant clams act as filter feeders, sifting planktonic debris from the water for food, and thus, help improve the overall water quality.