03 July 2015

Corals, mangroves and seagrasses of Pulau Hantu

Mangroves have settled naturally on the artificial seawalls of Pulau Hantu. While corals and seagrasses  have crept back into the artificial lagoon. On the outside of the seawall, the rich reef flats are still very much alive.
Alas, Mei Lin's Giant clams are lost. We only found one wild clam. We are quite distressed by this.


I started at the rich reef flats outside the seawall. The tide is very low today so much of the corals were exposed. Fortunately, the tide turned soon after sunrise, protecting the corals from being toasted.
We started our survey well before dawn. Just across from the pretty lights of the petrochemical plants on Pulau Bukom, there are living reefs.
Colourful colonies of Brain coral, Favid corals and Carnation corals.
Also Anemone corals, Mole mushroom corals and Ring plate corals, all doing well. I also saw many Tongue mushroom corals.
There are lots of Circular mushroom corals, among larger Pore corals. All the Pore corals I saw were not bleaching.
A closer look at the Circular mushroom corals in all sizes from tiny still attached to a hard surface, to large free-living ones.
Also called table coral because the colonies grow into flat table-like forms, the branching Acropora coral provides living spaces for all kinds of small creatures. They are hard to spot as they hide deep among the stony branches of the coral. On the high shore, there were small clusters of Montipora coral, but not large patches like those I've seen on the Terumbus.
How nice to see large colonies of electric blue Branching horn coral. So far, the only other place I've seen this coral in large numbers at Raffles Lighthouse.
Large colonies of delicate Lettuce coral and Disk coral.
The large patches of Galaxy coral are still there and they seem alright.
More colourful orals!
Only a few of the Circular mushroom corals were bleaching. Most of them were alright.
I saw one Brain coral that was bleaching, but most of those I saw were alright. Similarly, one bleaching Cauliflower coral, with most being alright.
The Asparagus flowery soft corals were a little yellowish. The Giant carpet anemones I saw seemed alright.
What is coral bleaching and why this is of concern on the Bleach Watch Singapore blog. Fortunately, the latest Bleaching Alert Areas from the NOAA website shows that Singapore falls outside the 'Watch' status. So let's hope our corals have passed the danger period for the year.
The only nudibranch I saw was this Blue dragon. Chay Hoon says the ID of this animal is being looked into and its name might change. There were also many White-rumped sea cucumbers, and I saw some of the usual crabs too.
It's easier to photograph fishes at night when they are less skittish. I'm not sure what fish this is.
Colourful life of all kinds cover the ground in deeper water. It is important not to get too close to the rich areas to avoid crushing these delicate marine life. You can also dive at Pulau Hantu! Join the volunteers of the Hantu Bloggers who have been conducting guided dives here every month for 12 years!
There are many large Leathery soft corals and they seemed alright. There are also mangrove trees that have settled naturally on the western seawall (blue arrow). I hurried over to have a look at them.
A view of the western reef flats outside the seawall with the mangrove trees on the left.
Among the trees I came to look at were the many Tengar putih that are growing here. They are all doing well, flowering and producing propagules. Pulau Hantu is the only place I know of where I can easily see many of these trees in a small area. The tree is listed as Vulnerable on the Red List.
Little mangrove saplings have settled on the sand around the bigger trees that are growing on the seawall.
More saplings settling on the sand around the lagoon.
One lone but very tall (about 60cm) sapling has settled in the middle of the lagoon.
Mangrove saplings have also started to settle on the eastern seawall. I first noticed this in Oct 2014.
Here's a view of the saplings on the eastern seawall.
One tree is already growing tall here. It appears to be a Mangrove cannon-ball tree. The bark isn't peeling a lot though.
Most of the Tape seagrasses in the northern lagoon were nice and long.  I also noticed that the lagoon is much sandier (less silty and soft) and the lagoon seems to be shallower.
Many of the Tape seagrasses were covered with a thick layer of hairy epiphytes.
There were patches, however, of 'cropped' Tape seagrass.
There are also Spoon seagrasses, although they are heavily covered in epiphytes.
Sadly, Mei Lin could not find any of the Giant clams she had grown from babies and put out in the wild. We are very sad.  The team did find a wild clam. There are many pressures on our shores. Let's hope Pulau Hantu stays safe until we next visit.

Photos by others on this trip
There are not enough low tides to do all our shores! So Kok Sheng checked out a Changi shore today. Here's what he shared on facebook.


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