On Monday, the department listed the five sites on its website that had been hit by the plankton boom, namely:
• Boat route between Koh Lan and South Pattaya
• Na Ban Beach
• Ta Waen Beach
• Tian Beach
• Koh Sak
The department said the plankton explosion had mainly been caused by wastewater coupled with rain that washed silt into the sea.
The department said the situation around the island was being closely monitored and it is seeking cooperation from local residents, tourists and fishermen not to dump garbage and wastewater into the sea.