Giant clams are one of the most ecologically important organisms on a coral reef, known as a keystone species. Like hard corals, giant clams use symbiotic algae (zooanthallae) to produce a shell that adds to the reef structure. In addition to this, they clean nutrients from the water that could otherwise go towards the growth of macroalgae, smothering and killing corals.
A single giant clam can filter 100s of litres of water in a single day, and only where there are giant clams do we see high coral abundance and biodiversity. Unfortunately, these slow growing clams are being harvested for food and decoration, a practice which is unsustainable and benefits only a few individuals. Save Koh Tao developed a long term nursery. to help repopulate Koh Tao’s reefs.
Any significant ecological benefits will likely only accrue where giant clams are present in healthy, i.e. self-sustaining, populations and hence their conservation is paramount.Neo and Todd (2013)
The breeding and propagation of giant Clams is done at Fisheries Department’s breeding centre based in Prachuap Khiri Khan about 3 hours south of Bangkok. The project was started under the auspices of the Queen of Thailand , Queen Sirikit. For the past few years, Koh Tao has been the recipient of approximately 1000 – 1500 juvenile giant clams each year for the development and improvement of our reefs.
Many of these have been placed in protective cages for a year and are around 1-3 years old when received. After a year of care these clams are transplanted on designated reefs under Koh Tao’s ‘Adopt-a-Reef’ program. Under the Adopt a Reef program, local environmental centres and dive schools take environmental responsibility for a particular dive site that they dive or visit frequently.