No mass coral bleaching at the Sisters Islands Marine Park

Volunteers checked up on the Marine Park shortly after the 'Circuit Breaker' was lifted. There was some urgency because Dr Jani Tanzil alerted us that mass coral bleaching may have started on our shores since the second week of June.

Healthy leathery soft coral on Small Sisters Island
overlooking Big Sisters Island during the predawn survey.

Dive surveys and intertidal surveys were conducted. Fortunately, during the actual surveys, no mass coral bleaching was seen at both Small Sisters Island and Big Sisters Island, although there were signs that corals had suffered some bleaching recently.


Here's Dr Jani's first alert on 20 June about possible mass coral bleaching seen at the Sisters Islands Marine Park and other shores. 

With permission from NParks, volunteers surveyed Small Sisters Island on 20 August. They did not see any large corals that were full on bleaching. About 1% were showing stress (paler than usual or with bleaching portions) or with recently dead patches.

Similarly, a survey of Big Sisters Island on 19 Sep found little actual bleaching, although there were signs of corals having recently died.

In the process of surveying Big Sisters Island, volunteers Loh Kok Sheng and Vincent Choo came across FIVE Fluted giant clams! Thanks to Dr Neo Mei Lin, our Giant Clam expert, who confirmed this after looking at their photos! Giant clams can also suffer from bleaching, so it was a relief to see that they appeared well.

The western shore of Pulau Tekukor is also part of the Sisters Islands Marine Park. Volunteer Vincent Choo shared what he saw during a dive survey there on 10 Aug. He reported little bleaching.

The sightings for mass coral bleaching were shared on the Bleach Watch Singapore site  and facebook page and compiled into a map of community sightings for all Singapore shores during this period. It appears the threat of mass coral bleaching has passed for now.

What is mass coral bleaching? Here's a brief introduction to the phenomenon.

Other happenings

Other happy news include the release of 119 critically endangered Hawksbill Turtle hatchlings at Sisters' Island Marine Park Turtle Hatchery on 23 Aug.