Field Trip 1: Sungei Buloh Wetland Reserve

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On 16 August, we visited the Sungei Buloh Wetland Reserve. The whole field trip was split into 2 lovely parts: the Mangrove Boardwalk and the Sungei Buloh Besar.

First though, an introduction to the place. The guide mentioned that Sungei Buloh only really took off when it was discovered by a few avid birdwatchers that it was a bird sanctuary. There were so many types of birds that many bird fanatics rushed over to observe them. In 2002, the place was declared a nature reserve. It became Singapore's first ASEAN Heritage Park in 2003. To this date, it is still a bird haven, and is frequented by many visitors, birdwatchers or not.

It was actually quite humid there, but fortunately not very hot since we visited in the morning. The smell of the mosquito repellant everyone had put on blasted our noses at full force immediately after we got off the bus. Cicadas chirped incessantly, like static that rings in your ears until you get used to it. The occasional calls of elusive shore birds that are only heard, but never seen. This was the elementary feel of the whole place.

As we were guided along the mangrove boardwalk, we were introduced to many different species of flora and fauna. Here are a few of them:

The yellow dots in the middle of the plant are baby spiders. The plant itself though, is known as the fishtail palm. Its leaves have oxalic acid crystals that can cause irritation to skin (so make sure you never touch them :O). Its leaves are also jagged to make it look like it has been colonised by other insects to discourage other insects from nesting or feeding on its leaves as they want to avoid competition. It has bipinnate leaves (leaves divide into more leaflets) and a really cool usage of the fishtail palm is that it can be used to produce jaggery (an unrefined sugar), palm wine, timber, and ornamental decorations.

The little mountain of soil in the picture is known as a mud lobster mound. It is a microhabitat for other organisms (e.g. ants), and is usually present at less salty parts of the mangrove. Mud lobsters aerate the muddy soil, which is beneficial for mangrove plants and animals. Crabs sometimes even take over and inhibit these mounds.

Our guide called the sea holly plant a "sweater"; you can't wear it and expect to keep warm though. It's just a term to describe how it deals with the salt in its environment: it excretes salt through the underside of its leaves. We were even allowed to taste it. The sea holly usually has square-shaped capsules for fruits, which explode when they're ripe, propelling its seeds from the parent plant.

Other methods of dealing with and flushing out the excess salt present in their living environment include roots that filter out the salt, as well as plants that store salt, and dispose of it later on.

An example of a plant that stores the salt temporarily is the buta-buta (blind-your-eyes). Its sap is corrosive, and can cause blinding (hence the name), or blisters to the skin. It exudes this poisonous white sap from all broken surfaces, so its probably not a very good idea to touch one, lest you break a branch. Its leaves are sometimes pounded into juice and exploited as fish poison as well.

The bakau putih plant has a large network of prop roots such that it can breathe. It is the main source of charcoal, as it has high caloric content and can burn longer and produce more energy. It's roots are also dense, so they're used to build wooden scaffoldings.

Its bark produces a smell which frightens away fish. Its seeds germinate when they are still attached to the parent plant, which is known as vivipary. These budding seeds are known as propagues, and are buoyant such that they can float away (across the seas) to colonise other places. The bakau putih seems to be one of the most common mangrove trees in Singapore.

And these are the propagues still hanging from the parent plant. These propagues can be eaten; apparently, PM Lee’s wife ate one once, and said it tasted like green apple. Interesting.

This is the cassina, one of the rarer plants in Sungei Buloh. According to the guide, there are only around 20 of these plants left in Singapore. It was falsely believed to cause vomiting in people at one point.

During low tide, tree climbing crabs come down to the ground to eat leaves. They remove fallen leaves in the habitat, which helps to relieve the stress on decomposition rates. A common sight in Sungei Buloh, they climb trees to stay above the water during high tide, and stay completely still; probably to avoid attention from predators. Not like that stops humans from finding them and eating them up though.

The horseshoe crab actually isn’t a crab. Instead, its related to the scorpion family. Its tail is not used as a weapon, unlike scorpions, but instead to flip itself over when it is upside down. Known as living fossil as it has not changed it's body structure for the past 400 million years. It's blood is blue like a crabs, since it contains copper to bind oxygen (less effective than haemoglobin). Instead of haemoglobin, it has haemocyanin. It's blood can detect gram-negative bacteria, which are usually quite hard to detect. Thus, it's blood is used for medical purposes. Scientists have recently discovered how to clone it's blood, so no more mangrove horseshoe crabs will have to be killed for their blood :)

And this is the tulu plant. It has a very distinguishable red calyx, and is pollinated by sunbirds.

The nypa palm has a fan-like leaf formation as shown in the picture. These leaves can grow up to 9m in height It has a translucent fruit that is used in ice kacang known as attap chee, also supplies brown sugar in chendol. It is also used to make attap houses as it is very durable. It is pollinated by bees. Its sap can actually be used for biofuel as well.

This plant is interesting due to its unusually tough leaves which causes water to roll off them in droplets. Fun fact: attap itself is actually a brown composite fruit which is edible, but the more popular part is the seed, which has an edible endosperm. This is actually tasteless, but in desserts, they taste especially sweet because retailers like to store them in syrup to preserve them.

In a mangrove, there are wonders of nature everywhere; up, down, left, right. This is a picture of a particularly big mudskipper through the gaps of some wooden planks. It stores water in its gill chamber, but can also breathe through moist skin. It can live out of water for more than a week as it goes out of water to find new sources of food, but not too long since it needs to keep its skin moist to allow air to dissolve for gas exchange. They are readily identifiable by round circular puddles formed in the mud. Occasionally, you can even see 2 of them fighting, usually to defend their territory.

Sacred to buddhists, as it is said that Buddha achieved enlightenment under one of these fig trees. In construction sites, all trees are chopped down except these (due to its sacredness). It is pillar-like, and can even break through concrete. Once, HDB was worried about fig trees growing under HDBs, so they got someone to study them! They also have very noticeable aerial roots. It is also known as a “strangler”, as when their seeds are deposited on other plants, they will suffocate that plant. It can grow up to huge sizes, one of the biggest found in Sri Lanka.

Walking towards Sungei Buloh Besar; when suddenly, monitor lizard.

Vanato salvator (genus name originating from the Arabic word waral (ورل), meaning monitor), or the Malayan Water Monitor can grow up to 3m (twice as long as Rayhan’s height!) and can weigh up to a whopping 50kg. Not bad, for a lizard. The monitor lizard is a cold-blooded animal; *ahem* sorry, an ectotherm, to use the correct terminology. This means that they lack a homeostatic (self-regulatory) internal heating system, and cannot keep themselves warm without external help (which is worrying, for an animal that spends much of its time underwater). Thus the water monitor can only regulate their temperature by basking in the sun to heat up their bodies, up to hours on end. However, this also means it does not need to expand energy through higher metabolism simply in order to maintain a relatively constant internal temperature. Water monitors feed on fish, frogs, rodents and even snakes, along with some cases of consumption of turtles and crocodile eggs.

Some fun facts about water monitors: their main genus Vanato is the second-largest genus of lizard, after the Komodo dragon. The members of Vanato are also highly intelligent, in terms of their feeding habit. One species, V. niloticus, can cooperate as a group to forage for crocodile eggs, which are normally difficult to obtain due to the mother crocodile’s protective nature. While one lizard distracts the mother crocodile away from her nest, the other lizard quickly darts in to snatch away the crocodile eggs before the mother crocodile can protect them. Additionally, monitor lizards have been known to be able to count until six!

There were quite a few tourists at the bridge above the Sungei Buloh Besar; we saw almost none at the Mangrove Boardwalk. We could overhear the guide complaining about how many tourists there were, and how noisy they were, which might have been disturbing the animals.. Aside from the tourists though, we could see the magnificent expanse of water in front of us; in fact, it was flowing below us. A wide, straight channel of murky green water, hiding the secrets of nature.

Ahem. Time to stop being metaphorical and dreamy.

 

Anyway, according to the guide, there were usually a few crocodiles lurking around the besar. Sure enough, she pointed out a snout of a crocodile that looked completely like a rock, or a twig. Can you spot it in the picture? Its eyes and nostrils are positioned at the top of its head, so it can remain hidden like that while breathing and looking around.

After that, we proceeded into a hut that overlooked an artificial pond. We had a small snack break there as well. Happy happy bellies :D (sorry that was just random. Ahem, back to the serious stuff.)

Sea almond (terminalia catapa) is salt tolerant. Its leaves can produce slight acid when put in water. Once, one of such leaves were going for 1 US dollar online, as it was in heavy demand by aquariums that needed the extra acidity in their tanks. This is literally “money that falls from the sky”.

Its seeds are edible as well. On closer inspection, its tree branches terminate at every level in a systematic manner.

After a while, a crocodile finally revealed itself! It was basking there in the sun on the sandbank (can you spot it?), with its mouth open. The guide mentioned that the crocodile might be waiting for prey, so it simply keeps its mouth open. It’s quite small, but at least it finally showed itself. They can reach speeds of up to 18 km/h in water; that’s alarmingly fast. It can reach sizes of 6.7m long, and weigh up to 1000kg (beat that monitor lizard). Its longest tooth is around 9cm long. They are carnivores (obviously), but seldom attack large creatures such as humans. If they did though, we’d be in trouble; they have a bite strength of up to 16000N! This is like having a 1600kg object crush down on you. Ouch. This enormous jaw strength is due to their jaw muscles. There is a lot of space in their skull for these muscles, and they’re adapted for shutting instead of opening. Amusingly, the jaws of a crocodile can be shut by just using several layers of duct tape. That might not be a very good idea though. Random facts: although they have rather small brains, it is possible that these crocodiles have a deeper language ability than we currently believe. 


 

Mullet fish spotted! This fish is unique in that it can use its muscles to jump out of the water for brief periods of time. They do this hopping motion to escape predators, such as larger carnivorous fish. In this case, in the relatively "safe" Sungei Buloh, without a lot of things eating them up, their numbers have escalated, and fast. As these fishes love travelling in groups, our guide told us that the groups were too big and the fish were a little too crammed for their liking.  They were probably jumping out of the water to try and beat the crowd to the front! This particular one, the guide reckons, had escaped from a nearby fish farm. One can only imagine how many many of them thrive in the murky depths of the Besar.

We also caught a glimpse of shorebirds and waders. They come from as far as Siberia, Russia. Migrates to as far as Australia when temperature is extremely low in Russia for food and warmth. They fly to Sungei Buloh usually at low tide. Sungei Buloh have specialised man-made ponds that are controlled such that water level does not rise too high, such that during high tide, the birds will land in these special ponds so visitors can see them.

One of the really interesting structures we saw (and with a live demonstration from our guide on how it works too :D), was the Sluice Gate put into place to regulate the water level in many of the ponds in Sungei Buloh. Originally, a long loooong time ago (not that long ago actually), many of Sungei Buloh’s ponds were used by prawn and fish farmers to farm prawn and fish. These traditional prawn or fish farmers stock their ponds and practice water exchanges to drain waste and let in nutrient-rich water regularly. Before harvesting, a complete draining of the pond is required to attain the yield. All these water regulations were able to be achieved, supplying the people living in Singapore a long long time ago with delicious prawns, all thanks to the Sluice Gates.

Now, Sungei Buloh’s many ponds’ water is still being regulated by these Sluice Gates. However, apart from one prawn pond that is used for demonstration purposes, the rest of the Sluice Gates are utilised to regulate some ponds for migratory birds as the mudflat is a feeding and roosting ground for them.

During high tide, there will be less exposed coastal areas for the birds to feed and roost. To boost the number of birds to cater to the needs of avid birdwatchers, twelve sluice gates have been placed at strategic points of each pond, facing the sea. As such, tide movements into some of these ponds can be regulated, ensuring that at least one of the three ponds present in Sungei Buloh will have a low water level even during high tides to enable birds to feed and roost on the exposed mudflats, boosting their numbers. As these ponds cannot be left unattended for a long period, there is a strict schedule to follow to allow both the organic nutrients and crustaceans (crabs, prawns and allies), different species of fishes and molluscs (snails, slugs, mussels and clams) to procreate within the ponds. Sluice gate gate management ensures a flux of vibrant oxygenated water teeming with rich minerals to rejuvenate the ponds.
 

The civet cat is a nocturnal creature. Its dung is used to produce coffee when these cats eat coffee beans. This coffee is considered gourmet and can actually be quite expensive.

Mangroves are a valuable part of our living habitat and community, both for humans and other organisms alike. Mangroves appear in saline environments, in coastal depositional habitats. Different kinds of mangrove plants and trees have various types of root systems. They can be prop, conical, matted, pencil or knobbly. All these specialised aerial roots enable the mangrove plants to survive well despite the limited the oxygen supply in the muddy soil. They also aid in the stability and support of the plant or tree into the ground to deal with the ever-changing coastal landscape.

These mangroves have many benefits:

Firstly, with their extensive root systems, they are able to reduce the impact of waves pounding onto shore. This helps to protect the shore from harsh sea or ocean current and even tsunamis. By having a mangrove to protect the coast of an island, it would greatly help to reduce the damage caused by such natural disasters. Imagine what would happen if there were no mangroves for protection and a tsunami comes and floods up and ruins your entire country! (And yes, your phone will be destroyed too oh no.) The gentler waves can also promote land creation to increase the span of an island.

Secondly, it is a safe environment for various marine animals to nest their eggs or give birth. Mangroves provide a natural nursery for fish, prawns and crabs by trapping microscopic organisms among the roots as food for these young organisms. The roots sticking out haphazardly also make it more difficult for bug sized predators to access, making the mangrove area very safe for the young organisms to grow healthily in their former years.

Being plants, the existence of mangroves allow for renewal of the damage caused by human activities, which might have resulted in an increase in carbon dioxide emissions and other harmful greenhouse gases. Through the process of photosynthesis, the mangroves, like all other photosynthetic plants, produce oxygen into and remove carbon dioxide from the atmosphere.

In addition, mangroves are beneficial in terms of our economy. Mangrove plants such as api api and bakau (meaning “fire”) are good sources of fire-resistant wood and charcoal. They have been used for producing premium quality timber for furniture and chipwood for paper manufacture. They are used to withstanding salt water and thus will not rot easily.

However, mangroves are starting to be viewed as dirty environments that are merely wastelands that can and should be removed to create more space for human activities. What people don’t realise is that mangroves are actually very clean, but rather it is the pollution caused by humans that are causing the mangrove landscape to appear so dilapidated. The “tangled mess of roots” we often see in mangroves help to filter sea water by trapping trash. Humans’ careless discarding of waste materials such as styrofoam takeaway boxes, plastic bottles, straws can only be trapped amongst the roots of our poor mangrove trees and waste away, sometimes causing harm to other organisms, at the same time.

We’ve dirtied these mangroves, killed some off and walk around acting like its our home. We do what we please there, leaving a trail of destruction behind us in the form of litter. Now, don’t you think its time for us to save them? First, as doctors always say, do no harm. It’d be pretty ironic if our efforts to protect mangroves cause even more harm to them. Thus, while visiting mangroves, don’t leave anything behind, and don’t take anything out: in other words, don’t litter, and don’t take anything that belongs to the mangrove. This applies if you see anyone else littering or damaging the mangrove as well: tell them! It’s always tempting to push these responsibilities to others, like the park cleaners, or someone else. We can’t all be like that; the animals aren’t exactly going to clean up after your mess. Help raise awareness on the state of these mangroves too. You don’t need to be environmental activists and raise signs demanding for change though; just telling people, and hopefully convincing them to join in, and help conserve these amazing mangroves. There’s even an annual NUSH cleanup community involvement project at Sungei Buloh that collected 122kg worth of rubbish over just a stretch of 375m last year! Alternatively, you can encourage your school to go for the “Adopt-A-Park” program to raise awareness on the conservation of the Sungei Buloh wetland reserve. Every little effort counts; no one is insignificant!

As you have seen, mangroves are lovely <3 and a very important part of our livelihood and we must do our best to conserve and preserve them! Let’s do our part together to reduce land and marine pollution which would possibly eventually harm our mangroves!