Friday, September 14, 2007

Mangrove Ecology at Sungei Buloh

Thursday afternoon, a big bunch of learning "ecologists" from NUS went to Sungei Buloh Nature Reserve for a field trip to study mangrove ecology. And believe me, everytime you go, there is something new for you to be marvelled at.

If you enter through Kranji, you might come across this railway crossing which has only one lane for a two-way traffic. Therefore, traffic jam always occurs near here though this place is not every populated.

Upon reaching the nature reserve, we were introduced to zonations based more on topography than species since our "compressed" mangroves are more heterogenous as compared to other undisturbed mangroves elsewhere from Singapore. From landward to seaward, the zonation goes like this: Back mangrove, mud lobster mound system, main forest, sandbank and then mudflat. One thing about the diversity of mangrove plants as compared to that from tropical rainforest is that species diversity is low as few plants can tolerate low oxygen, high salinity conditions.

Our first station is the back mangroves where it is found at tidal heights beyond where the highest water spring tide occur. What dominates the back mangrove will be Sea Hibiscus.

The next zonation will be the mud lobster mound and pool system.

Over here, the mud lobsters dig mud and unknowingly, they create huge mounds which are analogous to condominiums, even with swimming pool, in the forms of water pool. The height of the mound is advantageous to those plant which cannot tolerate salt because these plants can grow on the sides or on top of these mounds and be higher up from the salty water of the incoming tides. Growing on these mounds are mangrove ferns...

and sea holly. These plants can be identified by its jagged edges.

The main forest zone of Sungei Buloh is highly disturbed and therefore has more species of plants in a small area as compared to undisturbed mangroves. The common mangrove trees include the Rhizophora tree with stilt aerial roots, Bruguiera with knee like roots (as shown above) , and Avicennia with thin pencil-like roots.

And this is the flower of one of the Bruguiera species.

Even the huts along the boardwalk is so cute, with all the collages of drawings.

And hey, we saw this monitor lizard basking under the sun. Monitor lizards are the cleaners of the shores as they can feed on almost anything they catch. They also can "smell" the air with their tongue to track down prey. In Chek Jawa, we even saw one swimming and they are known to even swim underwater for half an hour.

Here is a fly on a leaf that has gotten my attention to take a snapshot before moving on as the teaching assistant shows us the different parts of mangroves.

This is a giant mudskipper which is actually a fish that can stay on land. How do they do it? They have hold water in their mouth and also breathe through moist skin. These fearsome predators even have two rows of teeth in their upper jaw, feeding on small fishes and crabs.

Talking about crabs, we have the tree climbing crabs. Why? Because they climb on trees! Duh. They climb high up during high tide to avoid being preyed upon. These guys eat mangrove leaves and seedlings and sometimes scavenge for meat.

The furthest seaward zone is where you can find the sandbank, as shown here. You can see many herons resting and feeding on the sandbank and also have a great view of Johor from here.

A close-up of the birds on the sandbank.

We then proceeded to the bridge over Sungei Buloh Besar and this photo shows the upstream portion where nutrients input into the mangrove ecosystem. There is a big name to explain this: allochthonous nutrient input.

And downstream, we find the river leading to the Straits of Johor.

Across again, another view of Johor. Sadly, we did not see natural shores along, but with modifications.

Here again we chanced upon this resident monitor lizard at the side of Sungei Buloh Besar. It is evident that there are the pencil-like thin roots which mainly belonged to the Avicennia trees.

Archer fish is interesting because they can feed on insects near the water surface by pumping out forceful jets of water to knock insects off leaves.

Our last stop was the main hide where we were told that many telescopium Rodongs can be found on the flat when the sluice gate drains the water out.

The whole trip was summarized with a short test and we were of course stressed over it for that short moment. Other than that, was a great trip. Thank God for wonderful weather despite nasty forecast from meterological station.

Sunday, September 2, 2007

An evening with the Saint

The evening tides have arrived and our first destination is to St John Island (Pulau Sakijang Bendera) which is 6.5 km south of Singapore.

No more waking up in the wee hours and having a headache on how to get public transport. One thing about having evening tides is that I compromised on the packing, was searching high and low to my dismay for my torch.

Setting off from Marina South Pier, the wildfilms and beachfleas gang headed southwest-ward. From this photo, we can see four areas, from the front, a rocky outcrop exposed at low tides, Sentosa cove, Keppel shipyard and the far back is the city landscape. Look at how busy our straits and coasts are, filled with human interventions. This is the price to pay for development.

And this nice lettering on the slopes of the island continues to welcome and tell everyone you're at the right place.

An evening session definitely includes a setting sun as the backdrop of the tranquil island.

Landing on the jetty, we were greeted with many fishermen and also a kuching. St John is indeed a great getaway from the hussles and bussles of the busy city life.

Though we did not visit the island for the sandy beach of the swimming lagoon, it was nice to see this sand castle made by well-wisher writting a "God bless" greeting. It has been since I-dont-know-when I have build sandcastles on the beach like a child, though I like to build them in the air.

St John shores has these natural rocky coast cliffs where fault lines are exposed, revealing the beauty and art of nature. Why are these cliffs pink, it is because of the oxidation of iron.

St John is an island that is filled and compacted with life. There are many soft corals and hard corals found, including this blue coral. Though it doesn't look blue but dark brown, it is named that way becasue it has a blue internal skeleton.

Very quickly, I spotted some spiny projections which resembles the spider conch (Lambis lambis). And overturning it, the camouflage from its back was exposed as having beautiful pinkish underside with the creature inside.

Chay Hoon, with her sharp eyes, spotted this pesudoceros flatworm. Though this species is more common than others, I really love it because the colours are really stinning with a striking yellow line across the white and blue body.

As the sunsets with a orangey glow behind the two sisters,

the gang continues to explore the shore creatures. Note the landslide behind. Landslides are mainly caused by exposure when vegetations are removed or when there is human intervention, like the path on top of the cliff. It is something that can be big scale and disastrous and engineers should never underestimate it.

Just as we were looking around, we saw this great billed heron stopping by. It was a great sight.

Back to the shores, we were enthrilled to see how colourful it is, with this sponge here of course.

And we also saw a number of this neptune's cup sponge, in bright yellow.

Phymanthus anemones are common, and among the others spotted are the moon snails prowling, the wandering cowries wandering (duh) and the tiny shrimps scrawling across the rocks.

Ron spotted a gigantea carpet anemone with a residential anemone shrimp on it.

Red egg crabs are also very common nearing the edge of the shore, this one here seems to be disturbed or interacted with the active swimming crab.

Ron, July and I spotted these greenish blobs at the reef edge. Ron was saying they are corallimorphs.

But as what I observed in water, they look more like anemones. Ron agreed too and we are still clueless as to what they are. Any ideas folks?

Octopus always show their mastery of camouflage, can you spot where this one is?
Staring into the details of the crowded living reef edge, I was pleasantly surprised to see these very tiny and cute hydroids.

Chee Yuan spotted the hairy projections at one of the rock crevices and Ron shared that it is most likely from the clam. Beside it is a cowrie, also well camouflaged.

I spotted this interesting thing on a rock, looks like a coral. Can anyone help me out with identifying it?

This black flatworm has yellow and white edges and it is the first time I saw such of a kind.

With Chay Hoon around, there will be more things to see. This carpet eel blenny was at first hiding under a rock with the head and tail exposed. After removing the rock, we can see this guy in full. Hehe.

And CH also found this really tiny hairy seahorse. Not only was it tiny, it was truly well camouflaged. Surely I would have missed it.

This is indeed the corallimorph that we common see and know.

More crabby creatures include brown egg crabs, velcro or decorator crabs etc.

We spent the last 15 mins on the sandy swimming lagoon and amongst the mass of molluscs found, I saw this loner and only Haddon's carpet anemone.

And the reason of being at the swimming lagoon is to look for these common seastars. Sadly, these guys are no longer common, due to overcollection.

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