11 June 2009

Mangroves of Pasir Ris

Today, my first look at this stretch of Pasir Ris mangroves and shores.
How nice to start a field trip at sunrise! The last few days, we ended our trips at sunrise or even earlier. It seemed a luxury to be able to stay in bed until 5am for a change.

Pools among the trees harbour all kinds of creatures, the most lively of these being mudskippers. Countless little ones scamper away, often just out of reach of a photograph.
This one might be the Dusky-gilled mudskipper (Periophthalmus novemradiatus). It's hard to be sure of the ID of a mudskipper from just a photo.

The soft silty mud under the trees is often covered with tiny little Red berry snails (Sphaerassiminea miniata).
But we didn't linger long under the trees. It's a glorious morning over a vast shore exposed by the low tide.
James bravely pushes on to check out this treacherously soft shore. The innocent layer of green Sea lettuce seaweeds (Ulva sp.) often giving way to mud up to the knees. But there's vast meadows of Spoon seagrass (Halophila ovalis) near the water's edge, promising all kinds of creatures hidden there.

I made a brief foray into the sand flats to check it out for anemones. There were some Haddon's carpet anemones (Stichodactyla haddoni), both small and medium sized ones.
Some of the usual Striped sand anemones, and this strange pink anemone with a striped body that I've not seen before.
But I eventually stayed on firmer ground to check out the mangrove area.
There are thousands of fiddler crabs on the sandy areas near and under the trees! There were lots of these Porcelain fiddler crabs (Uca annulipes). This is my first time seeing these fiddlers on the Northern shores besides at Chek Jawa.
And also lots of Orange fiddler crabs (Uca vocans) which I've seen on many Northern shores such as Ubin, Pulau Sekudu and Lim Chu Kang. These fiddler crabs are best differentiated by the shape of the enlarged pincer of the male crabs, and not by the colour of their pincers or their bodies.
I was watching this pair of fiddlers: a male (with one enlarged pincer) and female (with two small pincers). The male was busy trying to get the female to get into the burrow and she was busy trying not to get in, that they both didn't notice me until I started taking their photos.

The firmer sandy areas are crawling with Sand bubbler crabs (Scopimera sp.). The crabs are tiny and resemble the balls of sand that they create. Can you find the crab that is in the photo on the right among the balls of sand in the photo on the left? The size of the burrow hole generally gives a hint at the size of the crab that lives in it.
The upper shore of this stretch of Pasir Ris is edged by a stand of Perepat (Sonneratia alba). This is quite unusual: to be able to take a closer look at mangrove trees in nice clean sand on the mainland! Something a school trip could easily do, even at moderate tides.
Many mangrove trees like Perepat produce breathing roots that stick out forming something that looks like a bed of nails! It's important not to step on the roots as this hurts the trees. Also, the roots are home to all kinds of small animals such as crabs and snails.
And I also notice lots of little mangrove seedlings starting to grow among the Perepat roots! There were many different species of seedlings. I could see Api-api (Avicennia sp.) as well as Bakau (Rhizophora sp.).

Mangrove tree trunks also provide places for animals to hide and feed. Such as this interesting Onch slug (Family Onchididae). I got distracted by a crab and forgot to take its underside, sigh.
I also saw a really nice Portia tree (Thespesia populnea), also known as Baru baru.
Usually a scraggly small bush or even shrub, this was a magnificent tree with glossy green unmarked leaves. It was not only flowering profusely but for the first time, I saw the fruits forming under the withering flower petals.
When we first saw the tree, the sun was just rising and there were no open flowers, only buds. On our way home, we saw the open flowers! This rather rare plant is easily mistaken for the more common Sea hibiscus (Hibiscus tiliceaus).

Before starting the field trip, I had stopped by the Gedabu tree (Sonneratia ovata) planted near the boardwalk that I saw on a previous visit (and kindly identified by Dr John Yong). I wanted to see if it was flowering.
One of the flowers seemed to have finished blooming. But it was being affected by some sort of powdery fluffy pest. Oh dear.

The most exciting encounter, however, was to see the Lenggadai (Bruguiera parviflora)! All thanks to the tips shared by Dr John Yong.

Alas, like many of our mangroves, those at Pasir Ris are affected by marine litter.
Abandoned fishing nets get entangled in the mangrove roots, trapping marine creatures and affecting the breathing system of the trees.
Litter is even tossed into the leaves of the trees!

Marine litter is consider a very serious but preventable problem. Read more about the issues on the News from the International Coastal Cleanup Singapore blog which also has details on how you CAN make a difference on this issue.

There was also a sign warning people NOT to feed the monkey (singular). It's good to know that effort is being made to prevent our wild monkeys from getting used to being fed by people. And that early warnings are posted with even with only one monkey being sighted.
Monkeys that get used to being fed become a nuisance and often have to be killed. Monkeys should be left wild and free, such as the happy monkeys on Sentosa that I saw yesterday. More about why we should NOT feed the monkeys.

Read more about this trip on James' excellent Singapore Nature blog with lots more photos and stories of excellent finds.

1 comment:

  1. this shore looks nice and clean, friendly for nature noobs! the pink nem is very pretty!

    ReplyDelete

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