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January 27th, 2011
Giant Clams Get A New Home!

Two years ago, as part of our marine conservation program on Koh Tao we received 1000 giant clams (tridacna maxima) from the Thai Navy to raise until big enough to transplant onto the surrounding reefs.

Giant Clams in transit from Aow Leuk!	Christopher William Rowe-Roberts, clam in hand, ready to deposit on the reef.

The initial batch of clams were placed in cages in Aow Leuk Bay on Koh Tao’s south-east coast. Mortality rates where high during the first few months but two years on approximately 50% survived to maturity. 12 months ago the majority of these were transferred to the surrounding reefs in Aow Leuk with the remaining clams staying in their caged home.

Unfortunately the cages suffered some damage during the recent monsoon so we figured rather than fix the cages it best we simply transfer them out onto the natural reef. So as part of the ‘Adopt-a-Reef’ program a number of dive schools received some of the remaining clams for their adopted reef. Today Crystal Dive & Eco Koh Tao made their way to Aow Leuk and collected 22 giant clams from the collapsed cage on the bottom. Many of them have grown up nicely and were more than ready to be moved. For our second dive the boat made its way to Mae Haad and the much used Junkyard reef. IDCS Nathan Cook with the help of several volunteers currently diving, or training with Crystal Dive who took this opportunity to get involved in some marine conservation and helped us distribute the clams into the surrounding reef. When transplanting Giant Clams it is important that the underside be close to a suitable rock (or other solid surface) on which it can attach itself and not be open to predation from other animals. This is a critical time for the clams as it can take them many weeks, even months to secure a new footing. Newly certified Reef Check Eco Diver James Andrews with a giant clam ready for settling in Mae Haad!

Giant Clams require shallow water and plenty of sunlight to stay healthy. They are extremely important for maintaining water quality providing a natural filtration service for much reef water. Their colour comes from the symbiotic algae in their tissue. Many Giant Clams are fished out for their shells or for food in some places.

Showing off the Giant Clams before taking them down to their new home!	A couple of our Giant Clams in their new home!

Many of the clams were placed along our regularly surveyed Reef Check transect line in Mae Haad assuming that when doing our surveys we can also keep track of our babies in their new home.

Thank you to everyone who helped out today. PADI Divemaster Mads Frese and newly certified Eco Diver James Andrews who helped collect the clams and to conduct a Reef Check/Koh Tao Ecological Monitoring Program Survey in Aow Leuk. And thanks to the fun divers who gave up part of their fun dive to help us move the clams; Instructor Michael Steele, Christopher William Rowe-Roberts, Paul Streli, Jonas Fagerberg & Julio Macchiavelli.