Kusu Island still reefy, with Giant clams!

This rich reefs of Kusu Island lies just opposite the Central Business District, less than half an hour away by fast boat. A small team surveys the rich reefs that are now part of Singapore's second national Marine Park at Lazarus South-Kusu Reef. 

The corals are slowly recovering from the 2024 mass coral bleaching and we feel haven't quite returned to their former glory. This is quite worrying as we are expecting another round of mass coral bleaching next year. We also saw 3 giant clams and other fascinating finds. I will compile the rest of the team's finds later.

The reef edge outside the Northern lagoon is densely covered in hard corals. Today, the very low tide exposed a large extent. The situation seems similar what I saw in May 2025. Many corals seem alright, including large colonies. Towards the western side nearer Eagle Bay, there remains some less commonly seen corals like branching Acropora and delicate plateforming Montipora that look like tiered wedding cakes and large Horn coral colonies. There are still large colonies of Leathery soft corals at the reef edge, but fewer and smaller colonies at the seawall. I didn't see any bleaching corals. Here's a slide show of the northern reef edge.

Corals have settled inside the Northern lagoon. Challenging to survey in total darkness. But the situation seems similar to what I saw in May 2025 and Aug 2024. There remains far fewer live corals, and the area near the seawall opening was much sandier and bare. The large patch of Branching montipora corals remains mostly dead, with only those on the outer edge of the patch alive and not bleaching. Other large coral colonies were also mostly dead on the upper portion. But there were many small colonies of common coral growing, often on the dead coral patches. I didn't see any bleaching colonies, but there were a few with freshly dying tissues (bluish grey).

I had a look at the southern reef edge, facing Lazarus Island and east of the temple. The situation seems similar to what I saw in May 2025. A rich reef edge large colonies of Trumpet coral and small fields of Branching montipora coral! As well as a few mushroom corals. I also noticed many small to large colonies of Cauliflower coral - a few with small white patches. Most corals seemed healthy, I didn't see whole colonies that were bleaching. Here's a slide show of the southern reef edge.

Unfortunately, I noticed some large deep holes at the reef edge with piles of dead corals pushed up - possibly due to a boat striking the reef? Could this be something to do the ongoing works on the Kusu Island jetty? I didn't see the large Anemone coral colonies that I saw last year. Perhaps these were destroyed in the boat strike?

Today, we spot three Fluted giant clams (about 25cm long). One was at the northern reef edge, the other on the southern reef (photo by Richard), and yet another past the temple. 

Magnificent anemones remain abundant in the northern lagoon and northern reef edge. Today I saw clusters of anemones with white, purple and red body columns. These large anemones multiply by cloning themselves, clones having similar coloured body columns. One of them had several large clown anemonefish aka 'Nemo'.

Both lagoons had sprinkles of Spoon seagrass (tiny leaves) and Needle seagrass (narrow leaves). There were some sand dollars and moon snail, as well as Acorn worm signs.

What is the future of Kusu Island?

The rich reefs of Kusu Island of today are slivers of massive reef flats that were reclaimed less than one human lifetime, 50 years ago. Today, all these vast reef flats have been reclaimed, leaving very narrow margins outside the seawall that can only be accessed by non-divers at the very lowest tides. Check out the Historical maps of Singapore by NUS Libraries site where you can actually overlay the various maps over time and use a slider to see the changes.

Kusu Island was in fact originally a tiny outcrop where the temple now is. And during the annual Kusu Island pilgrimage, devotees would land by sampan. As captured by this iconic photo by Ivan Polunin, from "Once upon an island: A rare peek into our past" Scenes of old Singapore through the lens of the late naturalist Ivan Polunin. Wallace Woon, Straits Times 20 Sep 2023.

In May 2024, it was announced that the reefs outside the northern lagoon of Kusu Island would be part of Singapore's second national Marine Park at Lazarus South-Kusu Reef. It is good to cherish and protect what we have left. More on Singapore's second marine park: past, present and future.

Kusu Island is among the islands likely to be impacted by the upcoming Keppel-Tanjung Pagar reclamation started to start end of 2027. More about the potential impacts and responses to the EIA. Submit your feedback to HDB here https://form.gov.sg/6966fc4e7c5fe159af98b799

The Singapore Blue Plan 2018

The Singapore Blue Plan 2018 recommended the cluster of Kusu, Lazarus and St. John's Islands for elevated protection status.

The Blue Plan highlights that Lazarus, St. John’s, and Kusu Islands are established sites for coral nurseries as their shoreline offers ideal sheltered areas for growth of corals. Designating these islands as No-fishing Areas can bolster their rehabilitation. Protecting a larger cluster of islands means 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

Richard Kuah