Mangroves growing on Pulau Hantu seawall still doing well

Today, I focused almost entirely on the mangroves growing on the artificial seawalls of Pulau Hantu. Such a joy to do this with another mangrove enthusiast - thanks Kwan Siong! Amazing to see the mangroves, reefs and all kinds of marine life just opposite the huge petrochemical plants on Pulau Bukom.

We visited the large Nyireh laut growing on the seawall, and may have found another small treelet in the Southern lagoon. But sadly, someone had chopped all the saplings that settled on the Southern lagoon. My brief look suggest the corals are mostly alright. The rest of the team make all the special finds, I will update later.

While waiting for daylight, I was delighted to see happy clown anemonefishes in a Giant carpet anemone, just across the massive petrochemical plants, all still alight in the dark.

At sunrise, I got to the top of the seawall for a view of the mangroves growing here. A great view of the surrounding Terumbus, Pulau Hantu from the mangroves on the seawall.

Mangroves have settled naturally on the artificial seawall around the northern lagoon. I had earlier noticed this in Apr 09 (although they were probably growing there much much earlier). The trees are still growing very well. With fresh green leaves hardly chewed up by bugs or dinged by disease. Almost every tree was flowering or producing propagules. 

Kwan Siong and I revisit the rare Nyireh laut that we first saw growing on the seawall in Jun 2025. Listed as Critically Endangered in Singapore, we probably have only about 7 trees on our shores. I visit those at Sentosa Tg Rimau and St John's Island regularly.

We also noticed a small tree next to the enormous Nyireh bunga, and we think it might also be a Nyireh laut! It seems the treelet was there in Jun 2025, but not in  May 2022. The treelet had been chopped together with all the other treelets in the Southern lagoon. But it had managed to sprout new branches! While the Rhizophora next to it has not.

Heartbreaking to see that someone had chopped off all the young well-growing Rhizophora growing on the seawall of the Southern lagoon that I saw in Jun 2025. I first noticed this in May 2022 and they were okay in Jun 2025. Today, we even saw the chopped off portion of the trees on the shore, with a sheer clean cut on the trunk. Such a shame. But small saplings are starting to settle again on the seawall. Hope they will grow up unmolested.

Mangroves have also settled within the artificial Northern lagoon of Hantu Besear. Mangrove saplings settle among the lush border of Gelang laut on the high shore. And some grow quite large, including a tall Perepat near the seawall.

I only checked the corals at the mouth of the big lagoon on Hantu Besar. They were mostly boulder shaped corals. Almost all the Boulder pore corals had dying tissues (bluish grey). But most Merulinid boulder shaped corals were prefectly okay without even dead portions on the top. These were also growing on dead portions at the top of pan-caked shaped Boulder pore corals. There were still healthy corals in the shallow lagoon between Hantu Kecil and Hantu Besar. I didn't see any bleaching corals.

There were some medium sized colonies of Leathery soft corals of various kinds. As well as Asparagus flowery soft corals. All looked alright, although there were some pale patches on the flowery soft corals. I also saw a Magnificent anemone and Leathery sea fan.

Similar to our survey in Jun 2025 and Mar 2025, there remains hardly any signs of seagrasses. Few clumps of Tape seagrass with cropped leaves (about 20cm) heavily covered in ephiphytes. Even Spoon seagrasses (tiny leaves) remain sparse.

The ongoing Sudong reclamation is visible from the Southern lagoon of Hantu Besar.

From Port Marine Notice No. 55 of 2026 "Reclamation at Pulau Sudong" with effect from 08 Apr 2026 to 07 Oct 2026. The works involve the installation of navigational buoys, removal of metallic debris, demolition of abandoned jetty, dredging works, installation of marine staging platforms for soil instrumentation, infilling works, marine vibrocompaction, stone revetment works, and jetty construction to facilitate the reclamation and jetty construction works at Pulau Sudong.

Here is the location of Pulau Hantu and other nearby shores in relation to the Sudong reclamation.

What is the fate of Pulau Hantu?

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.

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.