About leaked oil and dying corals

Maritime biologists and government agencies disagree about the impact of the oil spill on marine wildlife.

Divers from the Department of Marine Science at Kasetsart University have found that the coral in shallow water off the coast of Rayong has turned white. Tar balls have been found on Khao Laem Ya and Had Ma Pim beaches near Rayong, and rocks are still covered in oil. An area of ​​five rai with seagrass is not affected.

The coral that has turned white (bleaching) is located at a depth of 10 to 20 meters. Thon Thamrongnawasawat, head of the Department of Marine Science, believes the coral may have been covered in oil at low tide, preventing the coral from breathing. It can take years to recover, as it grows at only 1 percent per year compared to 5 percent in other species.

The tar balls are formed at the surface of the water from oil that has weathered to a solid or semi-solid substance and washed ashore. Thon expects more to wash ashore in the next two weeks. It's important to clear them up. First, because they pollute the beaches; secondly because we don't know how they affect the ecosystem if they remain on or under the sand.'

University teams also took water samples: in three different places and at different depths. Sediment collected from and under the seabed is examined for heavy metals. Fish, shellfish and various types of plankton are also collected for laboratory testing. Thon says every animal species in the area, including worms, should be tested because they all play a role in the ecosystem. 'That process is labour-intensive and expensive, but necessary.'

So far, no damage has been determined at greater depths, but that says nothing about the long-term effects. It can take months or years for the harmful effects of the leaked oil and the solvent used to become visible. “We have to keep checking. Not just on and around Ao Phrao beach, because waves, tides and wind all play a role in the spread of the oil.'

No damage to coral

Contrary to the findings of Thon and his teams, a top official from the Marine and Coastal Resources Department (MCRD) says the coral at Ao Phrao has not suffered any damage. He stated this last week during a hearing by a parliamentary committee. The MCRD inspected twelve sites on the islands of Koh Samet, three other islands and Lam Ya cape on the mainland. Only part of the coral reefs exuded slime, according to the MCRD's report of the inspections.

The waters around Rayong contain 3.000 rai of coral reefs, 1.400 of which are in Khao Lam Ya-Samed National Park, where Ao Phrao Beach is located. The area also contains 3.800 rai of seagrass, 824 of which are in the national park. According to the MCRD report, the coral is not very fertile in some areas and has a density of 30 to 50 percent.

The Department of National Parks, Wildlife and Plant Conservation also sent a survey team to the area four days after the spill. The team couldn't study water less than 3 feet deep because it was still covered in oil, but they did at greater depths where the coral looked normal.

And then we have the Pollution Control Department, which is in charge of monitoring beach cleaning and monitoring air, water and sand quality. The PCD has also taken water samples, at 23 locations, but the results are not yet known. Searching for heavy metals and polycyclic aromatic hydrocarbons. If they are found, it can take at least a year before clear traces of contamination, especially by heavy metals, are detected.

(Source: Spectrum, Bangkok Post, August 11, 2013)