Mass coral bleaching expected in Mar-May 2027

Mass coral bleaching is likely in Singapore in Mar-May 2027. NParks will be monitoring.

Mass coral bleaching at Kusu Island, Jun 2024

Karenne Tun, group director of NParks’ National Biodiversity Centre said that while recent studies show that repeated bleaching in Singapore has caused relatively low immediate coral death – usually under 10%, and about 5% in the 2024 bleaching event – the reefs are changing and have “flattened” over time. Repeated bleaching and shifts to simpler reefs may affect coral spawning, limiting the  reefs’ long-term resilience even if they appear to recover.

Marine biologist Huang Danwei, deputy head of NUS’ Lee Kong Chian Natural History Museum noted that increased frequency of coral bleaching events means reefs have less time to recover between them. When corals do not recover, the flora and fauna that depend on reef habitats also decline in abundance and diversity.

According to third World Ocean Assessment: “The reefs of today will not be the reefs of tomorrow, and shifting baselines need to be considered when setting objectives, with respect to conservation, restoration and regeneration".

Current efforts include NParks’ 100k Corals Initiative, launched in December 2024 to plant 100,000 corals in Singapore over the next decade and beyond. It is the most extensive coral restoration effort in Singapore to date. Jani Tanzil, facility director of the St John’s Island National Marine Laboratory, noted that in Singapore’s case, where only about 10 sq km of reefs remain, there is no choice but to turn to this last resort of reef restoration to combat their decline.

Coral spawning muted in 2025 after mass coral bleaching in 2024

Once a year, on the fourth month, around four days after the fourth full moon of the year, our corals release eggs and sperm all at the same time! Called mass coral spawning, this year's event was 'muted', most likely because of mass coral bleaching in 2024. Scientists say the scale of the event was similar to the spawning in 2017, which occurred months after the 2016 mass bleaching event. 

However, Dr Karenne Tun, group director of NParks’ National Biodiversity Centre noted that while spawning was muted in 2017, it improved significantly in 2018 and 2019. “Thus, we are hopeful that the corals will recover to full fecundity within the next two years if our reefs are not subjected to any further thermal or other stressors,” she added.

More about mass coral spawning and this blog post on the 2024 event 

Singapore corals showing signs of recovery amid global coral bleaching event

Amid the largest recorded global bleaching event, Singapore’s corals are showing signs of recovery as sea surface temperatures begin to fall, with about 20 per cent to 30 per cent of them still showing signs of bleaching.

But the marine heatwave has taken its toll on some corals here, with 30 per cent to 55 per cent observed to be bleached in July, the National Parks Board (NParks) and National University of Singapore (NUS) told The Straits Times.

Mass coral bleaching 2024 in Singapore: community action

Share your sightings of mass coral bleaching. Volunteers will start consolidating community sightings in this map of mass coral bleaching in Singapore 2024. Scientists will be analysing the data shared. Share your intertidal and subtidal bleaching sightings on the Bleach Watch Singapore facebook group. This is similar to the volunteer effort in 2020.

The world is currently experiencing its fourth global coral bleaching event, the second in the last 10 years, according to press releases by international organisations NOAA and ICRI in Apr 2024. The final determination of a global bleaching event means bleaching has been confirmed within each Ocean basin. Mass bleaching of coral reefs, since early 2023, has been confirmed in at least 53 countries.

From the NOAA press release

For Singapore, as of April, we are in Coral Bleaching Watch (yellow). In 9-12 weeks, we are expected to be at Coral Bleaching Alert Level 1 to 2 (red to dark red). From the NOAA predictions for the Singapore Strait.

So what is coral bleaching? Why should I care?

Mass coral bleaching 2020 in Singapore: community action

Share your sighting of mass coral bleaching. Community sightings are consolidated in this map of mass coral bleaching in Singapore 2020. The map includes sightings shared on the Bleach Watch Singapore facebook group, of both intertidal and subtidal sightings.

Dr Jani Tanzil of the St John's Island National Marine Laboratory reported that "bleaching corals were observed in the second week of Jun 2020. Stark white coral colonies in shallow waters were visible from the surface and sea temperatures reaching up to 32ºC at midday."

Mass coral bleaching 2016 in Singapore: community action

Community sightings are consolidated in this  map of mass coral bleaching in Singapore 2016: In addition to intertidal survey sightings, the map includes sightings shared on the Bleach Watch Singapore facebook group. This includes some subtidal sightings.

Since June, the intertidal survey team has seen mass coral bleaching on 25 intertidal reefy shores. From our remote southern most reef at Raffles Lighthouse, to our northern most reef at Beting Bronok off Pulau Tekong. From the massive encrustation of corals on 2km of seawall at East Coast Park, to reefs on Kusu Island just minutes from the Central Business District. Even the reefs on natural Pulau Semakau next to the landfill and opposite petrochemical plants on Pulau Bukom.

Global mass coral bleaching to hit Singapore soon?

The third global coral bleaching event in recorded history has been declared by the US National Oceanic and Atmospheric Administration (NOAA).

Mass coral bleaching in Singapore's
Terumbu Bemban in Jun 2010

Boosted by an expected strongest-ever El Nino, bleaching may spread globally again in 2016. Why is global bleaching of concern? Does it happen in Singapore? What can I do about it? And more...

Update on coral bleaching at Sultan Shoal (Aug 2014)

The Maritime and Port Authority of Singapore (MPA) has been relocating corals at Sultan Shoal as part of their preventive measures to protect the corals from the development works for the future Tuas Terminal and DHI was engaged to carry out the relocation works.

Recently, MPA has updated its NGO partners on the observations of coral bleaching at Sultan Shoal.

Update on coral bleaching at Sultan Shoal (Jul 2014)

The Maritime and Port Authority of Singapore (MPA) has been relocating corals at Sultan Shoal as part of their preventive measures to protect the corals from the development works for the future Tuas Terminal and DHI was engaged to carry out the relocation works.

Recently, MPA has updated its NGO partners on the observations of coral bleaching at Sultan Shoal.

Western Australia coral reefs at risk from highest ocean temperatures in 215 years

High ocean temperatures off the West Australian coast are “unprecedented since at least 1795” and pose a significant threat to the state’s coral reefs, scientists say.

Bleaching Area Alert
on the US NOAA Satellite and Information Service

“Ocean temperatures have warmed so much and sea levels have risen so much over the last 150 years that every natural event is amplified,” Zinke said. “So any future heatwave is probably going to be more extreme. We’ve crossed this line where coral bleaching can now occur on a large scale.”

Mass coral bleaching starting in Singapore in 2013?

There were signs of mass coral bleaching at Terumbu Hantu when we visited on 28 Jun 2013.

Karenne Tun and Debby Ng also shared signs of bleaching on other shores. What is coral bleaching and what can an ordinary person do?

Intertidal corals can resist coral bleaching?

A study found that some Australian corals on the intertidal resisted bleaching during the 2010-2011 bleaching event!

Image: Paul and Jill

Sana Dandan says Kimberley corals in tidal pools at low tide at midday are subject to high temperatures and very high light intensity. She also says these are the two most common factors proven to induce coral bleaching, but the corals she observed appeared to be unaffected by them.

Major upgrades in NOAA’s global coral bleaching prediction and monitoring

NOAA announced a major advance in predicting mass coral bleaching, providing the probability of bleaching up to four months ahead.

Using the new seasonal ecological forecast system, NOAA’s Coral Reef Watch does not anticipate any large scale coral bleaching events in the Northern Hemisphere through October 2012.

NOAA has also significantly advanced near-real time satellite monitoring of the high ocean temperatures that can cause coral bleaching. A new generation version of NOAA’s product suite now provides daily 5-km satellite monitoring of coral bleaching thermal stress for reefs around the world. This represents 100 times finer resolution, more frequent observations, and more data than the current twice-weekly 50-km global satellite coral bleaching monitoring.

Findings from the 2010 Singapore coral bleaching event

Some good news from the mass coral bleaching on Singapore reefs in 2010, not only about Singapore reefs but globally!

Mass bleaching seen in June 2010
on a submerged reef off Pulau Semakau

In a recent paper, James Guest found that corals in Singapore and Malaysia that previously experienced severe bleaching in 1998, unexpectedly survived the 2010 event! The paper provides solid field evidence that certain corals in Singapore and Malaysia can cope with higher water temperatures.

Thai dive sites may be closed due to coral bleaching

Coral bleaching has damaged Thailand's Andaman Sea reefs more severely than the 2004 tsunami, said the Thai National Parks Director.

Bleaching corals
from the The Bangkok Post 8 May 10;

The Director of Research, National Parks, Thailand, Dr Songtam Suksawang, said 93.6% of coral at Surin, the Similans, Phi Phi, Racha and Phuket are dead. The coral bleaching rates by site are: Surin Island, 99.9%; Thachai Island 84%; Surin South 85%; Similan Island 89.3%. The species affected are the Staghorn, Ring, Double Star and Mountain coral

"Worst coral die-off seen since 1998" due to coral bleaching

"Certainly the worst coral die-off seen since 1998. It may prove to be the worst such event known to science," says the ARC Centre of Excellence for Coral Reef Studies about the recent coral bleaching.

Bleaching at Cyrene Reef in Jun 2010, photo by Marcus Ng
shared on the Bleach Watch Singapore flickr group

Many reefs are dead or dying across the Indian Ocean and into the Coral Triangle following a bleaching event that extends from the Seychelles in the west to Sulawesi and the Philippines in the east and include reefs in Sri Lanka, Burma Thailand, Malaysia, Singapore, and many sites in western and eastern Indonesia.

Coral bleaching in Singapore in the news

60% of Singapore corals were bleaching in mid-2010, but recently, there are signs of recovery, reported the Straits Times today.

Mass bleaching seen in June on a submerged reef off Pulau Semakau

As with bleaching elsewhere, bleaching in Singapore is mainly attributed to unusually high sea temperatures.

Malaysian coral under threat: AlJazeera video clip

Al Jazeera's Stephanie Scawen has been investigating the effects on Malaysia's Tioman Island.
Scientists have said that the first seven months of this year brought the hottest combined sea and land temperatures to parts of Southeastt Asia, since records began.

That has led to some of the worst coral bleaching the region has ever seen.

Iconic coral species the most vulnerable to bleaching

Evan Schwarten AAP Sydney Morning Herald 17 Aug 10;

The Great Barrier Reef's dominant coral species are among the most vulnerable to the effects of global warming, a new study has found.

A groundbreaking study into the immunity of coral species has found the iconic Acroporidae family to be among the most susceptible to outbreaks of disease or bleaching.

Bleaching in Indonesia leads to massive death on reefs

A survey of corals in Aceh, Indonesia revealed one of the most rapid and severe coral mortality events ever recorded. The scientists found that 80% of some species have died since the initial assessment and more colonies are expected to die within the next few months.
The Wildlife Conservation Society today released initial field observations that indicate that a dramatic rise in the surface temperature in Indonesian waters has resulted in a large-scale bleaching event that has devastated coral populations.