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 Muhd Nasry!
In the process, we think we might have come across a rare
Nyireh laut! The rest of the team saw a Burrowing giant clam, colourful fish and marine life. Corals seemed mostly okay.
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). It seems the trees have grown much bigger over the years.
Most of the trees that were large (6m or taller) were
Bakau kurap and
Bakau pasir, with a few
Bakau minyak. Also one
Perepat (conical pneumatophores sticking up among the rocks) and
Nyireh bunga.
Today, for the first time since
Jan 2011, I walked at the top of the seawall! I usually only have a look at them from the ground up. The trees on the western seawall of the northern lagoon have grown much larger! Making it quite tricky to walk around them on the seawall.
But it was easier to take a closer look at the trees from the top of the seawall.
Tengah putih was especially abundant. But there were also plenty of the more commonly encountered mangroves like
Bakau putih,
Tumu and
Api-api bulu. All the trees appeared healthy and most were profusely blooming and producing well formed propagules.
While on the seawall, Nasri and I think we came across a rare
Nyireh laut! 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. Update: Confirmed most likely to be Nyireh laut (Xylocarpus rumphii). Thanks to Hock Keong from NParks for the exciting chat on this. I'm motivated to look for the tree in other seawalls!
Mangrove saplings have also started to settle on the north-eastern seawall. I first noticed this in
Oct 2014. Today, I noticed more and larger saplings. Compared to
Jul 2020, when I saw fewer saplings than what I noticed on
Jul 2015.
Today, most of the saplings were
Bakau kurap and
Bakau pasir, with a few
Bakau minyak - those nearer the high shore were taller and well formed (team members for scale). There was a small shrubby
Api-Api putih on the high shore, and on the wall a small well formed
Bakau putih treelet and what looks like a small
Nyireh bunga treelet.
In
May 2022, I noticed that in southern lagoon, some mangrove trees have also settled on the seawalls. Today, the situation seems similar, with young well-grown
Bakau kurap and
Bakau pasir on the western seawall.
The big
Bakau putih tree growing on eastern seawall seems to have grown a lot since
May 2022!
Some mangrove trees have also established quite well inside the northern lagoon. Growing to quite a large size. Many saplings also settle nearby.
The two enormous
Perepat trees growing between Hantu Besar and Hantu Kecil are still very much alive. I don't often take a close look at the mangroves on Pulau Hantu. I did so on
May 2022,
Jul 2020,
Aug 2017,
Jul 2015,
Oct 2014.
As usual, the rest of the team make all the special finds. A small
Burrowing giant clam! Also '
Nemos' in anemones,
Copperbanded butterflyfishes, razorfish, cardinalfish, file fish and other colourful fish. The always amusing large
Very hairy hermit crab. As well as nudibranchs of all kinds.
The team also surveyed the reef and it appears most of the corals remain alright. Similar to our survey at a lower tide in
Mar 2025, it seems the reef edge is back to normal with some parts dense with the usual variety of common and less commonly seen corals. The large colony of
Goniopora corals is still there together with other less commonly seen corals like
Anchor corals. Also
Circular mushroom corals and other kinds of 'long' mushroom corals, and
Sunflower mushroom corals. They all seemed mostly fine.
In the Southern lagoon, I saw several healthy corals that look like they were freshly smashed with a hammer. Still not sure what happened.
There have always been many medium-sized
leathery soft coral various kinds here. As in
Mar 2025, the team didn't see any that were bleaching. They also saw
Asparagus flowery soft corals, Spiky soft coral. Also many
Giant carpet anemones (a bit pale but not bleaching),
Frilly anemones, a
Bubble tip anemone,
Fire anemone. As well as
Sea mat zoanthids, zoanthids and
corallimorphs. They were all fine.
There are large stretches of sandy shores in the artificial lagoons. Today, a small boat was beached on the mid-shore. These sandy shores are still alive with
Common sea stars, large
Fan shell clams and large
Garlic bread sea cucumber - suggesting that this shore is not heavily harvested. Similar to our survey in
Mar 2025, there remains hardly any signs of seagrasses. Few clumps of
Tape seagrass with medium length leaves (about 30cm) heavily covered in ephiphytes. Even
Spoon seagrasses remain sparse and tiny.
Although it lies just across the petrochemical plants on Pulau Bukom, the shores of Pulau Hantu are rich. It was nice to see many families out exploring the reefs this sunny morning.
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 2018Pulau 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 surveyChe Cheng NeoTammy LimMarcus NgJames CabatbatOthers on the survey: Ian Mun, Mud Nasry, Isaac Goh, Jayden Kang
