Saving Singapore's Giant Clams
28 February 2010
"We hope that clams can be cultured to produce hundreds, if not thousands, for research and restocking, and even eventually to supply local aquariums."
Dr Peter Todd, Department of Biological Sciences
RESTOCKING CLAMS: Dr Peter Todd and Ms Neo Mei Lin, a Master of Science student both from the NUS Department of Biological Sciences
With their attractive shell exterior and meaty flesh, giant clams (family Tridacnidae) have been fished as food and for decorative purposes for hundreds of years. Present at an alarmingly low number on Singapore's reefs, researchers at the Marine Biology Laboratory of the NUS Department of Biological Sciences (DBS) are about to embark on an ambitious giant clam restocking programme. The project will be facilitated by NUS' own research vessel "The Galaxea", which was launched recently.
Restricted to coral reefs of the tropical Indo-Pacific, giant clams are the largest of all bivalve molluscs. They are one of a few reef invertebrates that harbour photosynthetic symbionts (algal cells) in their tissues. Giant clams produce calcium carbonate shells during photosynthesis which eventually become part the reef. While alive, their shells contribute to reef topography as well as provide habitats to other organisms. In addition, giant clams are a source of food to animals such as fish and crabs.
Principal Investigator Dr Peter Todd of NUS DBS has studied giant clams for the past three years with support from the NUS Academic Research Fund. This research has led to a number of papers being published on various aspects of giant clam behaviour, ecology and defences. Dr Todd said that the knowledge gained by his team will be channelled into a restocking programme. He hopes that clams can be cultured to produce hundreds, if not thousands, for research and restocking, and even eventually to supply local aquariums.
As a first step, Singapore's reefs are being scoured to count and profile existing giant clams. These surveys are mainly being carried out by Ms Neo Mei Lin, a Master of Science student who SCUBA dives along the reef searching for clams. At low tide she goes for reef walks to survey reef flats that would be covered by two to three metres of water during high tide. To date, she has conducted close to 40 trips to some 17 islands around Singapore. She has found a total of 22 giant clams incorporating three species: Tridacna crocea, Tridacna maxima and Tridacna squamosa, from an area of ~45,000 m2. Tissue samples are also being collected for future genetic work.
On how "The Galaxea" will help their research, Dr Todd said: "The experienced crew on board know all the local reefs and sea conditions, especially the currents. This makes going out to sea much safer. "The Galaxea" is designed as a diving platform and much thought went into making her and efficient an effect research vessel. It is also fast, which means that more sites can be visited in a day." Mei Lin added that there is plenty of deck space as well as benches in the cabin for working with samples.