Global Warming

Sea water temperature tests to see impact on turtle population

APINYA WIPATAYOTIN - BKK Post 3rd Oct 2007

The Marine and Coastal Resources Department is monitoring sea water temperatures at five major turtle nesting grounds to study the impact of global warming on their population. The targeted areas are Koh Surin, the Similan islands, Tai Maung beach and Prathong beach in Phangnga, and Koh Kram in Chon Buri province. The move comes after international marine biologists recently found evidence that a rise of just one degree Celsius in sea water temperatures can stop the development of male turtles.

Unlike mammals, including humans, where sex determination is chromosomal, turtles' and crocodiles' sex is determined by genes which react to the temperature during the incubation stage of their eggs. Marine biologist Kongkiat Kittiwattanawong, of the Phuket Marine Biological Centre, said the optimum temperature for turtle hatching is 29.5C. ''Only at this temperature can we hope to see the same number of male and female turtles hatch in the same nest.''

A study of the impact of rising sea temperatures on sea turtles in Malaysia suggested that the warmer climate has led to a sharp reduction in the male sea turtle population, said Mr Kongkiat. As a result, fewer female turtles come to nest. ''The number of female turtles nesting on Malaysian beaches has shrunk from about 2,000 turtles 10 years ago to only 500,'' said the marine biologist. Measuring the sea temperature at their habitats would help Thai scientists come up with proper plans to safeguard the sea turtle population. Besides studying global warming's implications on marine animals, marine biologists are also working on artificial insemination of rare sea turtle species to boost their numbers. If successful, Thailand would be the first country in the world to artificially breed sea turtles.

The project, jointly run by the Phuket Marine Biological Centre and Kasetsart University, has picked the Olive Ridley turtle, locally known as Tao Ya, as a pilot species. Veterinarian Sontaya Manawattana, the project's team leader, said semen of Olive Ridley turtles aged between 20-30 had already been collected.