As with coral reefs around the world, Singapore reefs suffered a mass bleaching event in June 1998. Sea temperatures around Pulau Hantu and St John's were elevated by 1-2 deg C from March to June 1998. 50-90% of all reef organisms in Singapore were affected, particularly the hard corals, soft corals and anemones. The bleaching effect extended till 6m, the lower growth depth limit for coral growth locally. Sea temperatures returned to normal in August 1998. A study of the stressed colonies was undertaken during this period. 10 out of 35 coral colonies died from the stress, and the genera Sinularia and Euphyllia were most affected. Other colonies showed various signs of stress, such as growth of turf algae and silt accumulation, leading to partial mortality
