Giant clams at Pulau Semakau (East)

One of the reefiest shores lies next to Singapore's only landfill and near petrochemical plants on Pulau Bukom. A team surveys even though the tide was not as low as we expected.

The corals seemed alright and we find 6 Giant clams! There were also lots of large sea anemones, colourful crabs, nudibranchs and other interesting marine life.

This shore has always been full of clams. Today, Marcus found close to one another, a young Fluted giant clam (about 20cm) AND a old Burrowing giant clam (about 12cm - in yellow circle)! Lon and Richard found more elsewhere, so in total we might have seen 4 Fluted alive and 1 dead, plus the Burrowing giant clam. Will have to deconflict their photos before we can be sure of the total count.

Lon saw two large Fluted giant clams (30-40cm) but only managed to photograph one. Richard found another large one too, Marcus found a young Fluted giant clam  (about 20cm). Sadly, they also saw the shells of one large dead Fluted giant clam. But we also found 2 Burrowing giant clams, Marcus found one about 12cm embedded among coral rubble, and Rui Quan found a smaller one embedded in living coral.

Collage of photos by the team.
Links to their albums below.

The rest of the team make all the special finds! The Magnificent anemones were still abundant - purple and red body columns, also Giant carpet anemones and also possibly the less commonly seen Merten's carpet anemone. Colourful crabs were abundant, and the team saw Bigfin reef squid, the usual nudibranchs.

Collage of photos by the team.
Links to their albums below.

Today, the tide wasn't as low as we expected. But some of the more intrepid team members nevertheless checked out the reef edge. I surveyed the mid-water mark. I saw a large colony of Lettuce corals, some Brain corals, Anemone corals and the usual boulder shaped corals. The scattered patches of Branching montipora corals near the Landfill seawall are mostly alive but have not formed a dense 'field' (yet?). I first noticed them in Feb 2019. All seemed fine.

As in the past, the shore is dominated by large colonies of Leathery soft corals of various kinds. There still many large Asparagus flowery soft corals with some Spiky flowery soft corals. I didn't see any that were stressed or bleaching.

Near the seawall, there are still dense growths of Chocolate sponges - also common on other parts of Pulau Semakau. Button zoanthids remain common covering large areas of rubble. I saw various sponges including a Barrel sponge. I saw one Giant carpet anemone, some Frilly anemones, the rest of the team saw many Magnifica anemones. There were also many crabs, well documented by Rui Quan.

The narrow stretch of sandy shore near the seawalls also had many signs of life. Many oval moon snails, which suggest their buried prey is also present. Also many buried Acorn worms. I also saw a pair of buried horseshoe crabs, Richard saw another buried pair too. There were very sparse far apart patches of Spoons seagrass with tiny leaves. Richard saw Tape seagrass with moderately long leaves (about 30cm) near the reef edge. The Sargassum was not in full bloom here today.

More about Pulau Semakau

Just as Changi Airport and Changi Beach are not the same even though they are near one another and share a name, Pulau Semakau is NOT the same as the Semakau Landfill. The Landfill was created by destroying all of Pulau Saking, and about half of the original Pulau Semakau by building a very long seawall. Fortunately, the landfill was constructed and is managed in such a way that some of the original mangroves, seagrass meadows and reefs on Pulau Semakau were allowed to remain. It is NOT true that the construction of the Landfill created the marine life found on Pulau Semakau. The marine life was there long before the Landfill was built.

Here's a view of the shore we surveyed. This was taken on our Jul 2023 survey when Kelvin flew the drone and gave us awesome new perspectives!

What is the fate of Pulau Semakau (East)?

Pulau Semakau (East), Terumbu Semakau and even Pulau Jong and Pulau Sebarok are slated for massive reclamation outlined recently in the Long-Term Plan Review.

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.

Landing near the Landfill seawall
on a shore thick with soft corals.

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.

Large leathery soft corals with
petrochemical facilities on Pulau Bukom on the horizon.

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 the survey

Richard Kuah


Marcus Ng


Rui Quan Oh


Jason Ooi



Lon Voon Ong


Meijuan Foo


Samuel Lau


Mathias Luk


Others on the survey: Mathias Luk, Isaac Ong.