Overview: Giant clams (Tridacninae) are the largest living bivalve molluscs in the world, where one species – Tridacna gigas – is known to grow up to ~1m long and weigh over 300kg. They are highly conspicuous on the reefs, with their vibrant mantle colours and large shells. Today, there are 10 extant species mostly distributed in the shallow tropical coral reefs of the Indo-Pacific region. Giant clams have been mentioned to play important ecological roles on the reefs, such as food, as shelter and as reef-builders. Hence, their presence on reefs goes far beyond their aesthetic value.
Since pre-history, giant clams have been useful to man as food (flesh) and material (shell carbonates). With the recent advances of exploitation methods and accelerated habitat loss, giant clams in major areas of the Indo-Pacific are facing local extirpations. To curb any further decline in wild stocks, there was a concerted effort by several institutions in starting up breeding and culturing programmes. Aquaria-reared juvenile clams were later used for restocking and restoring decimated clam-reefs.
Singapore Case Study: Giant clam research has been ongoing for more than a decade in Singapore, where early research focused on improving mariculture techniques. Later research looked at the autecology and behaviour of larvae and juveniles. More recently, research has gone back to re-looking at key issues related to the conservation and management of giant clam populations. In particularly, to support the recent initiatives of restocking giant clams onto Singapore’s reefs.
Coral reefs of Singapore has experienced massive changes over the last few decades. As we become more urbanised, we are losing much of our natural coastline to land reclamation. As a result of coastal development, local flora and fauna have been reclaimed over, including the giant clams. Population surveys of giant clams revealed that we have lost two species (Tridacna gigas and Hippopus hippopus) while the remaining species are in extremely low densities (Tridacna crocea, T. maxima, and T. squamosa). To prevent the loss of our iconic marine invertebrates, restocking initiatives are underway in hope to give these majestic creatures a chance to thrive here.