Tuesday, September 18, 2012

Berlayer Creek & Bukit Chermin Boardwalk

Officially opened on 2 January 2012, the Berlayer Creek and Bukit Chermin Boardwalk is part of the 2.1km-long Labrador Nature and Coastal Walk. The boardwalk runs for about 960m along the 5.6-hectare Berlayer (or Berlayar) Creek, home to one of the few natural riverine mangrove forests left in Singapore, before it winds towards Keppel Island.

Berlayer Creek is actually part of what used to be a small tidal river in the southern part of Singapore. Urban development work has claimed most part of the original river system, but a small portion near the estuary was spared. The area was named after a historic rock formation, Batu Berlayer, which means “Sail Rock” in Malay, that stood at its estuary. This rock formation, together with another similar-looking one on the opposite shore of Tanjong Rimau on Sentosa, once formed some kind of "gateway" for boats. Due to these two sharp rock formations, the gateway was called 龙牙门 in Chinese, meaning Dragon Teeth's Gate.

The National Parks Board has done up a very nice online guide on this nature spot, and hence I will focus more on some of the things to note, and the ecological aspects along this boardwalk instead.

Dos & Don'ts
  1. Stay on the boardwalk, or you may end up trampling the flora and fauna.
  2. Bring water and some light snacks, as you can only buy drinks at the end of the boardwalk at the cafe at Keppel Marina or from the vending machines at Labrador Park.
  3. Keep your volume down, or you may disturb the very animals you want to see, and they may hide away from you.
  4. Take nothing but photos, leave nothing but foot prints. Bring your litter out with you, and never take anything from the forest. Poaching has resulted in severe reduction in the population of much wildlife in many places.
  5. You may want to bring insect repellent just in case, though I personally have not encounter many mosquitoes there.
  6. Please bring a cap/hat in case of sunny weather, and raincoat/poncho in case of wet weather. I would also recommend bringing a few plastic bags to keep your electronic products in case it rains.
  7. Bring a camera along, but remember to have a plastic bag to keep it dry in case it rains.

What to Expect at the Boardwalk

The entrance to the boardwalk is located near the Labrador MRT Station. Do check out the various cultivated native plants around the MRT station before you enter the boardwalk beyond the pavilion.

Once you enter the boardwalk, you will be greeted by a beautiful riverine mangrove forest. Riverine mangrove forests are those that occur along tidal rivers. As a result, the river has more freshwater during low tide, fed by its tributaries upstream, but gets inundated with sea water during high tide. In a typical riverine mangrove forest, the trees are usually taller and healthier, as the area will be enriched by nutrients from its tributaries. However, due to development, the main source of freshwater for Berlayer Creek is now is left with a small drain, and hence the amount of nutrients received by the forest is also affected.

Like other mangrove forests, the plants found in a riverine mangrove forest still has to adapt to the various challenging conditions - the soft and unstable mud, the lack of oxygen in the soil, and the salt (which has a drying effect). As a result, most mangrove plants spread their roots widely for more stability; develop aerial roots to take in oxygen from the atmosphere; and either block most of the salt at the root level, or excrete salt through glands on the leaves.

Berlayer Creek is home to the largest population of the Bakau Pasir (Rhizophora stylosa) on mainland Singapore. This is a nationally vulnerable mangrove tree with hard and heavy wood traditionally used for making charcoal. It relies on its roots to exclude salt from entering the plant through a process called ultrafiltration. The thin and long structures seen hanging from the trees are the seedlings, not fruits - the seed develops shoots and roots while still attached to the tree. Mature seedlings are dispersed by water and have a greenish collar. The seedling floats horizontally for a few weeks, during which the root (lower part) will absorb water and become heavier, eventually causing the seedling to tip and float vertically. As the tide goes down, the vertically-oriented seedling will sink into the mud or other suitable substrates.

The Api-api Ludat (Avicennia officinalis), a common magrove tree, is also found here. "Api-api" means "fire-fire" or "firefly" in Malay, as some Avicennia species are noted to attract fireflies. Research indicated that roots of Avicennia species also exclude some salt from entering the plant. It also has glands to excrete salt that is not excluded at the roots.

After the short loop among the trees, the boardwalk continues along side with the forest. Several interesting coastal and mangrove plants can be seen along the trail. In the photo above, you can see a Malayan Banyan (Ficus microcarpa), which is a fig tree, with the long dangling roots. As fig trees produce figs very regularly, they are able to provide regular food supplies for all kinds of animals such as birds and monkeys, unlike other forest trees that fruit perhaps once a year or even once every few years. In fact, such large fig trees play a critical role in providing food and shelter, and studies suggest the number of such fig trees limit the number of animals found in a forest.

The authorities had planted many native plants along the boardwalk, making this a nice trail to learn some of our native coastal plant. I will just highlight a few of the planted ones here:

Many young Gedabu (Sonneratia ovata) have been planted here. This critically endangered mangrove bears round persimmon-like fruits which are edible. It uses ultrafiltration to block the salt at the roots, just like the Bakau Pasir.

The Limau Hantu (Suregada multiflora) is another nationally critically endangered tree planted here.The fruit resembles small lime, hence the Malay name "Limau Hantu" which means "ghost lime". Studies shown that extracts from this plant has antibacterial and insecticidal properties. More recent studies showed that it has some anti-HIV and anti-cancer properties as well.

Yet another critically endangered tree planted here is the Sea Teak (Podocarpus polystachyus). The timber from this tree is hard and durable, and is used in some places to make furniture and house interior. It is also planted for ornamental purposes.

Of course, looking at planted trees can never be as interesting as finding the wild ones. Apart from the Bakau Pasir and Api-api mentioned at the beginning of this post, there are a few other mangrove and coastal plants here like the Bakau Putih (Bruguiera cylindrica), Buta-buta (Excoecaria agallocha), Nipah Palm (Nypa fruticans), Mangrove Derris (Derris trifoliata) and Sea Hibiscus (Talipariti tiliaceum). But it would be a lot more interesting to try to spot the ones that are really uncommon at this particular mangrove forest.

The Chengam (Scyphiphora hydrophyllacea) is rather commonly seen in our other mangroves, but somehow only a few can be found at Berlayer Creek. The small fruits are cylindrical and green, and they are dispersed by water.

The Teruntum Merah (Lumnitzera littorea) is an endangered mangrove tree. The authorities had planted many young ones along the boardwalk, but there is one huge and tall wild one among the wild trees. It has pretty red flowers, blooming in clusters. The small and somewhat corky fruits are buoyant and dispersed by water. The wood is hard and extremely durable, and is used for the building of bridges, wharves, cart axles, flooring and sleepers. It has a rose-like scent, making it popular as a cabinet timber.

You will sharp eyes to spot the Kalak Kambing (Finlaysonia obovata), a critically endangered climber. The fruits appear like a pair of horns, and hence the common name "kalak kambing", which means goat's horn. The young leaves of this plant are apparently eaten by some as a vegetable.

The hardest to spot, however, is a tall and mature Berembang (Sonneratia caseolaris), a nationally critically endangered mangrove tree closely related to the Gedabu mentioned earlier. I only know of less than 10 wild trees left on mainland Singapore, the others are: three (possibly a young fourth one to be verified) at Woodlands; one at Sungei Buloh; and one at Kranji. Several other wild ones can still be found on Pulau Ubin and Pulau Tekong though. Like the other Sonneratia species, the flowers usually bloom at night and are pollinated by nectar-feeding bats and moths at night, and birds in the morning.

Apart from the plants, the usual mangrove animals can be seen here too.

The mudskippers are among the easiest to spot. The above is a Giant Mudskipper (Periophthalmodon schlosseri). This is the biggest species of mudskipper in Singapore. This fish can survive out of water by holding water in its mouth and gill chamber. It is rather aggressive and hunts small animals such as crabs and worms for food.

The Collared Kingfisher (Todiramphus chloris) can also be seen, if not heard, here. Apart from small fishes, it feeds on small crabs, shrimps and insects too. Apart from kingfishers, many other birds, such as green pigeons, orioles, bulbuls, sunbirds and even a few migratory waders, can be seen here.

If you are lucky, you may chance upon the Plantain Squirrels (Callosciurus notatus). They feed mostly on fruits and leaves, though they may also eat insects and bird eggs.

Many butterflies and moths can be seen here, and hence it's no surprise you may see caterpillars here too. The above is an Atlas Moth (Attacus atlas) caterpillar. The Atlas moth is the biggest moth in the world in terms of total wing surface area, and its wingspan is also one of the widest, up to 30cm.

The boardwalk will bring you towards the see and eventually to the Bukit Chermin section of the boardwalk. While you are here, remember to look down to see if there are any schools of fishes around. If the tide is low, you can even see little crabs!

Do also check out the rare Johor Fig (Ficus kerkhovenii) growing on the cliff as you head towards the marina.

And here's the Marina at Keppel Bay!

If you look down, you will notice that there are lots of soft corals and other organisms growing on the sides of the floating pontoon!

Here's a closer look - can you see a clam, soft corals, seaweeds, and a pair of tunicates (the thing below with a pair of holes each)?

You can even find colourful cave corals!

If you still have energy after the walk, you may want to consider going to Labrador Nature Reserve, which is just nearby, where more nature awaits!


Anonymous said...

Friend, you are amazing. Thank you for making all these information easily assessible.

innocenet nature lover said...

thank you, Ron, for the nice closed up picture of the flora and fauna, it helps a layman to understand and appreciate the mangrove better.