Mass coral bleaching at Terumbu Pempang Tengah

At dawn, a small team lands on this huge submerged reef that lies near Jurong Island and major shipping lanes.

We are specifically checking for mass coral bleaching which was expected and seems to have started to affect some of our shores. We estimate about 20% of hard corals were showing signs of stress (pale, pink or with pale patches) with about 15% were outright bleaching. While about 50% of soft corals were showing signs of stress (pale patches, more yellow than usual), only about 10% were outright bleaching. 

As usual, the rest of the team make all the marvellous finds. Tammy spotted a large Burrowing giant clam, AND the rainbow over it. Also small and large anemonefish in Giant carpet anemones and Magnificent anemones. And a Cushion star and the nudibranchs. Kelvin also encountered a large nurse shark!

Photos by Tammy Lim.
Link to her album at the end of this blog post.

Here's a video of some of the mass coral bleaching we observed. High res photos of all cnidarian sightings on wildsingapore flickr.

It was nice to come across some uncommonly seen corals: Boulder horn coral (was slightly stressed), Lettuce coral, Tongue mushroom coral and Circular mushroom coral - all not bleaching.

I looked at corals that in the past bleached first: Cauliflower corals and Brain corals were all bleaching, while most Sandpaper corals were okay or pale, with only a few outright bleaching. Most of the Flowery disk corals were bleaching, only a few were okay. In reverse, most Goniopora corals were okay, with only a few bleaching. 

There are not a lot of hard corals on this shore, even on the reef edge. Most of the corals are boulder shaped. Today, while about 20% were showing signs of stress (pale, pink or with pale patches) only about 15% were outright bleaching. 

I came across 3 patches of dense Branching montipora corals. All had mostly dead corals in the centre of the patch with bleaching corals on the edges of the patch. Although there were a few small clumps that were not bleaching.

Thanks to Kelvin for surveying a huge northern part of the terumbu. Among his sightings, was a patch of Acropora corals that were bleaching. He also saw a large bubu on the reef edge.

There has always been many leathery soft corals of various kinds on this shore. In fact, I've often called this terumbu 'Land of the Leatheries'. With many large colonies covering large areas. Although about 50% were showing signs of stress (pale patches, more yellow than usual), only about 10% were outright bleaching. 

Other cnidarians can also bleach, so I looked out for those too. One Giant carpet anemone was a little pale, the rest I saw were okay. I saw one Magnificent anemone and it seemed fine - I have never seen these anemones bleach even in full blown mass bleaching events. I saw one Bubble tip anemone - these bleach very easily even outside of mass coral bleaching periods. I saw many Frilly anemones - most were okay.

Most of the Asparagus flowery soft coral I saw were pale and a few were bleaching. Most of the zoanthids I saw were alright, a few were bleaching or pale. The corallimorphs I saw were alright.

The situation today is similar to what we saw here in Jul 2016 during the last Global Mass Coral Bleaching event. But if we are not yet at peak bleaching, it could just be the beginning. The NOAA prediction for the Singapore Strait doesn't seem to suggest a sharp worsening in the weeks ahead. Let's hope for the best!

There were sprinkles of seagrasses of various kinds on many parts of the shore: sand bar and sandy areas in between rocks. Mostly Spoon seagrass with small leaves, heavily covered with epiphytes, and some with large leaves which were cleaner. There were also many clumps of Sickle seagrass. There were some longish Tape seagrasses. The situation looks worse than what I saw in May 2023 and May 2022.

Ian and I came across 3 large fish traps (bubu) laid on the reef edge. The rest of the team also saw similar traps all around the terumbu.

What is the fate of Terumbu Pempang Tengah?

Terumbu Pempang Tengah lies close to the planned 31ha reclamation at Eastern tip of Pulau Sudong. Other shores near the impact zone include Terumbu Bemban and Terumbu Raya.

Pulau Hantu and all the terumbus west of it are slated for massive reclamation outlined recently in the Long-Term Plan Review. Singapore's submerged reefs are often out of sight under the high tide and thus forgotten. Let's hope these terumbu stay safe until we can visit again.

The Singapore Blue Plan 2018

Pulau Semakau and nearby islands and submerged reefs have been recommended by the Singapore Blue Plan 2018 for Immediate Conservation Priority. The Blue Plan recommends the intertidal and subtidal marine areas of Pulau Semakau and adjacent Pulau Hantu, and Pulau Jong to be designated Marine Reserve.

The Blue Plan highlights that Pulau Semakau and its associated patch reefs comprise many ecosystems: coral reefs, mangrove areas, intertidal sandflats, seagrass meadows, and coral reefs. The subtidal area of Pulau Jong is larger than the terrestrial area. Pulau Hantu is a popular dive site has seen increasing interest in the past decade due to biodiversity awareness. If protection is accorded to these three islands, zonation plans for use can be implemented to manage tourism and human impacts.

DOWNLOAD the Plan, SUPPORT the Plan! More on the Singapore Blue Plan 2018 site.

Photos by others on this survey

Tammy Lim


Kelvin Yong Part 1


Part 2


Che Cheng Neo



Others on this survey: Jonathan Tan, Ian Mun.