Sunday, September 30, 2007

September Transect Day 2

It's Day 2 of our september transect! Though quite a number of volunteers could not make it on the last minute, my worry was gone when I saw today's friends working extra hard on the transects. Yesterday was also the first time I met a few of them too!

This is one of the two teams with Yilin, Demin (with the quadrat) and the experienced Siyang. While we reached the start point, the tide was still yet to be completely receded so there was a bit of wading to do.

And this is the same group in action. Transect 2 is the toughest in terms of terrain yet they broke my record and completed it very fast, of course without compromising on accuracy. Well done!

And here we have the other team in action, with Yujie, Sheong Leng, Nicholas and Jian An. They spotted a number of interesting animals along the transect and that's reassuring.

Also, Chek Jawa was kind of crowded from the boardwalk side as it was a Saturday. The Nparks guided walk was ongoing too while we see Adelle and Choon Beng on the ground too :)

And here we have Jian An and Sheong Leng with a pretty sunset backdrop while they were keeping the transect lines. Jian An's sole fell off and he had to wear Sheong Leng's booties to work the last transect, while the barefooted Sheong Leng helped us looked after our belongings at the sandbar. Working with barefoot is obviously a no no as there are many nasty sharp things hidden on the lagoon.

Nicholas and Yujie! This is Nicholas' first time (Jian An's also) down to an intertidal shore and they said they really found the place to be interesting. That's nice. This is also Yujie's second time helping me out with the transect. Thanks.

While we were moving from transects to transects, we encountered many interesting animals, including this seahorse at the seagrass lagoon.

This is a tiger moon snail. Other animals found along the way where I have no time to take photo will be lots of grown-bigger sandfish sea cucumbers, brittlestars, sandstars, hairy seahares etc.

We completed our 3 transects within target, that is before it turns totally dark. This is because yesterday's last transect photos turned out blur. It was also difficult to do video-ing of the whole stretch in total darkness with lights from the torches combined together. Therefore, work has to be done real fast while we redo one of yesterday's transect in addition. So horray! Mission accomplished. Thanks to all of the hard work of the volunteers.

We had a bit more time to spare so the guys could explore the wonderful shores a bit. Heard interesting things from them after which, including an exciting find of the warty sea cucumber which I have yet to see before in CJ. Yujie found this real small catfish. Look at the size as compared to the cockle shell. This is really cute.

Hidden beside the rock is this Salmacis sea urchin.

There is also this venus shell with the siphon sticking out a bit. Ironically, I saw many of these guys at Changi Village where they sold seafood.

Today's team was efficient and quick. The cleaning up was done in a moment, as compared to previous times of trying to untangle tapes in hours. Perhaps they heeded my warning to never entangle the tapes which will be a disaster. Haha.

As the cleaning was going on, I went to the storeroom and get our things out and realized ants invaded my big bag. Ended up washing the whole bag and getting rid of the ants, together with many bites. Soon, we hopped up to Uncle Chu's van and back we go with the bumboat. Finished everything at 9pm.

A group photo before we left for separate ways and also for well deserved dinner at Changi Village. A BIG thank you to all who came and help. Really appreciate everyone's effort, contributing to Chek Jawa in one way or another.

The story repeats where I had to sort out the enormous tons of tapes to clean and dry at home. :P

Anyway other than thanking everyone for the effort and precious time taken to help out, also want to thank God for ensuring everything run smooth when manpower was lesser. The weather for the second day was much better than the first and we could lay the line with much ease. There were no rain, so that's very optimal. Haha.

Looking forward for the next trip where we are going to monitor different groups of animals. That will be October 27. Anyone interested to join for the working trip, please email me at koksheng at Pls take away any spacing from the email add and replace at with @, this is to prevent spamming. Thanks and take care to all. See you soon.

Saturday, September 29, 2007

September transect day 1

The September low tides are finally here and we have a bunch of friendly and enthusiastic volunteers who decided to help out. Here we have Raymond, Suwen and Robyn (left to right).

And then Paul and Yijun. I'm sorry Peihao and Bingquan were not in the bumboat photos.

This time, we decided to use big flags with the poles so that they can be visible for maintaining straight lines. This is one group trying to put in the flag into the tide that hasn't reached minimum yet.

And here is how the transect tape looks like with the flag.

Here is another team in action, working hard on their transect.

As you can see, the lines were easily crooked because today was really really windy. Was really tough trying to make things straight. Therefore, we decided to bury some parts of the line to make sure that they don't run away! Good idea.

This is the group that did the longest transect.... a stunning 500m or half a kilometre across. And that is Pulau Tekong's "holiday chalet" in the background.

And wow, Chek Jawa is indeed recovering. Those baby sandfish sea cucumbers have grown quite a bit! That's very encouraging. Furthermore, they are quite commonly found too at the seagrass lagoon.

I'm sure this tiny noble volute is another sign of good recovery.

Sunset is always pretty and it's the first time I appreciate it in Chek Jawa since the evening tides have just started.

This is beautiful. Don't you agree?

We worked till 7 plus and while walking back, this is the part where everyone has to cross the wooden planks across a dam-thingy (not damn).

After washing up,enjoying the bits of food and drink, Uncle Chu brings us back safely to Ubin jetty where a quick bumboat ride returns us to the concrete jungle.

Frankly speaking, I really enjoyed working with today's friends. Thank you ALL for making everything pleasurable. Hope you all have had bits of fun too. Here is a group photo at the end with Paul pointing not to a street lamp, but a moon!

Thanks everyone for the recommendations suggested for next such trip. Will keep it in mind.

Ok, here's the big and round moon. We'll see it again tomorrow! Till then.

Tuesday, September 11, 2007

Remember Chek Jawa

Yesterday went to watch this docu-film at picturehouse. It was the closing film for the 7th Asian Film Symposium.

Because I only got a chance to know Chek Jawa in person this year, I have missed a lot of action. Especially when it was still a wonderful place before the mass death and when everyone contributed their heart and sweat to save this place.

I am so glad to watch the film and see how hard everyone worked to salvage whatever they can and each one of the volunteers that came from all walks of lives made a difference indeed!

Snippets from the 2001 transect reminded me of how tough it can get for the volunteers and helpers to "chase" against the incoming tide and work doubly hard in a terrain where you can get sunk in mud knee deep. Yet many were glad to have done something for the nature in Singapore.

Thank you Eric Lim for this great film and indeed, from all the laughter yesterday, everyone enjoyed watching it. It must have been heartfelt for those people who have done the salvage works themselves back at 2001.

More details of this film here.

And let us not only remember Chek Jawa, but to also ensure such a piece of wonder continues to exist for the younger generations. Mass death doesn't mean Chek Jawa is gone. It is obvious that recovering already occuring and estauries are very resilient and dynamic. Give it time, it will recover :-)

Sunday, September 2, 2007

The mussel beds in Chek Jawa

Something new appeared in Chek Jawa after the mass death early this year.

Huge patches of blackish slime looking thing were found covering huge areas of the intertidal flat.

They are usually found in the boundaries of the seagrass lagoon and the sandbars.

A closer look reveals holes in them which contains a tiny mussel with byssus threads around them, forming a mat of mussel bed over the whole area.

Gastropods like to eat these mussels. And we also bunches of pink and yellow stuff that looks like a carnation are actually eggs of a muricid snail.

And this is whole the shell of the mussel or also called the Asian date mussel looks like.

According to Joseph Lai, the person who discovered Chek Jawa, he shared that plenty of this smallish Asian Date Mussel can also be found around Pulau Sarimbun - right around the foot of the island as well as the nearby rocks of a shoal east of it.


From a couple of readups, this is what I got from journals (references below).

"The Asian date mussel, Musculista senhousia is an Indo-Pacific mytilid that was unintentionally introduced in the early 1990s in the north-eastern Adriatic Sea, and actually occurs with large populations also in Tyrrhenian (Gulf of Olbia) and Ionian (Mar Piccolo) coastal areas.

Mussels live semiburied in subtidal soft sediments, secrete byssal threads to attach to conspecifics, and build extended mats that alter the nature of the sediment inhabited by commercial infaunal bivalves."

Below are some FAQs for you to know more about them. They can't be ignored. Most of the facts are taken from NIMPIS, 2002.

What is its scientific name and classification?

Musculista senhousia. Phylum: Mollusca, Class: Bivalvia, Subclass: Pteriomorphia, Order: Mytiloida, Superfamily: Mytiloidea, Family: Mytilidae

What are their dimensions and how does it look like?

Maximum length of around 30mm and has a smooth, thin shell which is an olive green to brown in colour, with dark radial lines or zigzag markings.

In which part of the habitat can they be found?

From the intertidal to subtidal habitats (to a depth of 20m) and on soft or hard substrata. It prefers to settle in groups on soft substrata, but is capable of fouling wharf pilings and man made structures.

When settled on hard substrata the mussel will not form a protective cocoon. It is a highly adaptive species, and is able to tolerate low salinities.

In which part of the world can you find these mussels?

Native range: Russian Federation, Democratic People's Republic of Korea, Republic of Korea, Japan, China (CSIRO, 2000), Singapore (OBIS, 2006).

Known introduced range: USA (USGS, 2006), Canada, Mexico (Cohen, 2005), New Zealand, Australia (Allen and Williams, 2003), Israel, Egypt, France, Italy, Slovenia (CIESM, 2005), Tanzania, Madagascar (Mastrototaro et al. 2003).

What is byssus thread and what is it for?

It is used to construct a cocoon which protects the shell. This cocoon is made up of byssal threads and sediment.

How does it grow and reproduce?

M. senhousia is a species with high fecundity, rapid growth, a short life span and good dispersal ability, making it a successful invader.

It has separate sexes, with males and females spawning at the same time. The larvae of this species are planktonic, and have been recorded in the plankton for up to 55 days. It can reach an adult size in only 9 months, and its life span is typically no longer than two years.

How does it feed?

This mussel, like most mussels, is a suspension feeder. It consumes organic matter and many planktonic organisms from the water surrounding it.

What feeds them then?

Diving ducks and oystercatchers have been recorded feeding on M. senhousia, and it is also consumed by many species of carnivorous gastropods. In San Diego Bay, field experiments have indicated native gastropods may prevent M. senhousia from establishing dense beds.

What are its impact to our shores, like Chek Jawa?

It can dominate benthic communities and potentially exclude native species. It settles in aggregations and is therefore able to reach high densities.

The byssal mats formed by the mussel may restrict the growth of some species of seagrass.

The byssal mat may also cause an increase infaunal density and species richness as it provides additional habitat for many species.


1. Crooks, J.A. (1998) Habitat alteration and community-level effects of an exotic mussel, Musculista senhousia. Marine Ecology. Progress Series 162, 137– 152.

2. Mistri, M. (2003) The non-indigenous mussel Musculista senhousia in an Adriatic lagoon: effects on benthic community over a 10 year period. Journal of the Marine Biological Association of the UK 83, 1277– 1278.

3. Mistri, M. (2004) Prey preference of Carcinus aestuarii: possible implications with the control of an invasive mytilid and Manila clam culture in a northern Adriatic lagoon. Aquaculture 230, 261–272.

4. NIMPIS (2002) Musculista senhousia species summary. National Introduced Marine Pest Information System (Eds: Hewitt C.L., Martin R.B., Sliwa C., McEnnulty F.R., Murphy N.E., Jones T. & Cooper S.). Web publication

5. by Global Invasive Species Database