6 years after the mass mortality event

It has been almost 6 years since the fateful mass mortality event that occured in Chek Jawa. My first visit to this special shore was exactly on the date that we witnessed the mass death.

Despite not having to see how the shore was like in the past, many stories, accounts and photos did the job for me to compare the shore before and after the heavy rains in December 2006 and January 2007.

Going down to the shore with Teamseagrass has allowed me to check out how the shore is doing, especially after the monsoon season. I am glad to see that many of the Carpet anemones (Stichodactyla haddoni) in the northern shore are still doing well! No signs of bleaching or uprooting.

Here's a view of the southern shore with the huge carpet anemones among the seagrass lagoon.

Many of the carpet anemones also are found on sandy substrates such as those in the photo collage above. There seems to be more carpet anemones than my previous trip one year ago!

Here's a different perspective of the carpet anemones with their photos taken using an underwater camera.

Interestingly, I witnessed how an unfortunate crab which happened to swim across a carpet anemone got stung and slowly was brought towards the centre of the oral disk where the mouth and stomach is located. It really worked like a conveyor belt.

It is heartening to still see dugong feeding trails on Chek Jawa. In fact, we have also seen them on various shores of Changi.

During low tide, shore birds such as these terns rest and feed on the large expanse of shore exposed. At the background is Pulau Tekong.

Among the many critters that the birds feed on would be these circular stuffs... What are they?

These are actually Cake sand dollars (Arachnoides placenta) found buried slightly underneath the sand. The cake sand dollars are still found in abundant numbers on the shore... this is a good sign that the recent rain did not affect the marine life significantly.

On one of the sand dollars, I managed to find a parasitic snail preying on the echinoderm.

How about other soft-bodied invertebrates that would respond poorly to very low salinity, such as the sea cucumbers? Apparently, many of the sea cucumbers such as this Garlic bread sea cucumber (Holothuria scabra) look fine.

Here is an assortment of the different types of sea cucumbers encountered on the trip.

What is slightly worrying would be that this trip was the first time I saw so many Warty pink sea cucumbers (Cercodemas anceps) on Chek Jawa and that some of them seem to be decomposing. This could be a response to the recent rains in which salinity was lowered to a certain limit that these sea cucumbers start to deteriorate. 

Nevertheless, the other marine organisms were alright. So it was not alarming for us.

Due to the scorching sun, I did not find any of the usual sea stars except for this uncommon Luidia sand star (probably Luidia hardwicki).

I couldn't find the huge numbers of Button snails (Umbonium vestiarum) that can be found on the sandy shores of Chek Jawa. Nevertheless, I managed to stumble on one live individual. Hopefully more can be found elsewhere. 

With Chay Hoon's microscopic eyes, she found this tiny Tiny black gymnodoris nudibranch (Gymnodoris sp.)! This is probably my first sighting of this nudi on Chek Jawa.

A washed up Ball flowery soft coral was found just right beside one of the boardwalk pillars.

And in it, there's a little colourful brittlestar!

The boardwalk legs are well encrusted with many types of living organisms such as sponges and ascidians.

A quick look at the rocky shore revealed the usual assemblage of rocky marine life such as this Blue-spotted flatworm (cf Pseudoceros indicus).

Ending off the quick look of Chek Jawa, I took my underwater camera for a dip again to look at the lush seagrasses of the shore.

The seagrass habitat is a great haven for carpet anemones....

and also Cerianthids (Order Ceriantharia).

Animals wise, I also found a Noble volute (Cymbiola nobilis)...

and even a huge Razor clam (Family Solenidae).

The seagrasses in the lagoon are doing very well despite the shifting sands of the ever dynamic sandbar. Here's a photo with our intrepid Teamseagrass volunteers in action.

According to the latest 7 million population Land Use Plan, Chek Jawa may not exist for long and we may once again face the threats of losing it forever.

From Ria's blog post, the plans in the north include a road link from the mainland jumping off at Punggol, crossing to Pulau Ubin through Chek Jawa to jump off to Pulau Tekong before circling back to the mainland on Changi East. Proposed reclamation (in yellow) will bury Pasir Ris shores, Pulau Sekudu and Chek Jawa as well as a large amount of shore at Changi Beach.

What can one person do about this?

We can't take our shores for granted! You can make a difference! Simply explore, express and ACT!

Visit our shores before they are gone. Join nature activities at our wild places, like those listed on wildsingapore happenings. Share what you've seen. Volunteer for them.

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More photos of the trip here: http://www.flickr.com/photos/koksheng/archives/date-taken/2013/01/27/

Chek Jawa with Dr Dan

After about one year of absence from the intertidal shores of Chek Jawa, I had the honour to be back here again this time with Dr Dan and his students!

Every year, Dr Dan leads a group of students from the Duke University's Nicholas School of the Environment on an Urban Tropical Ecology in Singapore trip and will never fail to share Chek Jawa to his students.

Since Dr Dan and I have not been down to the shores for a year, we could very quickly figure how much the shore has changed! Other than the ever-shifting sand bar, we noticed something delightful... the Carpet anemones (Stichodactyla haddoni) seem to be coming back slowly but surely.

Here is an assortment of the different carpet anemones with different colours. They used to be so common and abundant before the mass death in 2007 such that they look like landmines on the sandbar.

Some of these carpet anemones have settled well among the lush seagrasses of Chek Jawa.

We saw many juvenile carpet anemones on the sand bar and this is a good sign!

One Common sea star (Archaster typicus) was found during the trip. I did not really have the opportunity to look for the colony of them on the sand bar as the tide was not very low.

Buried or semi-buried on the sand bar are sea cucumbers and sea stars such as this Smooth sea cucumber and the Plain Sand star (Astropecten indicus).

We stumbled across this dead plain sea star with lots of snails feasting on it. This of course is not a result of any physical stress such as drop of salinity but a natural occurence of feeding / scavenging on dead animals.

I got the sense from this trip that the number of Cake sand dollars (Arachnoides placenta) on the sand bar has dropped. It could be because that the tide was not that low. We noticed many pecked sand dollars with the star-shaped jaw exposed. These sand dollars were recently predated on by shorebirds.

We tried to look for the Button snails (Umbonium vestiarum) and after a while, Ria shared with everyone that she has found live ones on the sand bar! The density of these snails are not high but these snails seem to be bigger than usual. We also found one Lined moon snail (Natica lineata) which is actually a predator of the button snails.

Dr Dan found a rare snail! This is the Naked moon snail (Sinum sp.) which I think has not been sighted at Chek Jawa before.

The mantle of this snail is such that it cannot fully retract back into its flat thin shell. It sure can stretch itself and elongate quite a fair bit!

The empty shell of a Tun snail (Family Tonnidae) was spotted! Are living ones lurking somewhere out there?

Cindy found this large shell of a Bonnet snail (Phalium glaucum) that is occupied by a hermit crab. The living version of this snail is actually rare and not commonly sighted.

This is an interesting view of the cerianthid which is also known as peacock anemone. The cerianthid actually lives within a tube which is visible in this photo from top down position.

We came across this washed up Common sea pen (Pteroides sp.) with a porcelain crab living within. It was found quite high up near the mangroves.

Surprise surprise! It was great to spot the dugong feeding trails again!

Here's Dr Dan with his students having a closer look at the trails. The trail seem to suggest that two dugongs were feeding on the seagrass together!

Before we left, we had an aerial view of the shore from the tall Jejawi Tower. 

It was indeed wonderful to be back at Chek Jawa to see how it is recovering since the mass death. As for now, I do really hope to be back on a super low spring tide to check out the coral rubble. My previous check up on this fragile but rich habitat was in 2009. 

Checking Chek Jawa (April 2011)

It has been a really long time since I last stepped on the shores of Chek Jawa! The previous time was during January in 2010 which was more than a year ago. How has Chek Jawa been? I had a quick look at the shore while the Teamseagrass volunteers were busy surveying seagrasses.

The Carpet anemones (Stichodactyla haddoni) are one of the first organisms that I had a look to see how they are doing on the shore. These anemones are still not as abundant at the southern sand bar when compared to the northern sand bar. This photo shows the anemones at the north of Chek Jawa.

Many of the juvenile carpet anemones that I have seen back during my survey days a couple of years ago have grown bigger along the northern sand bar. This is indeed heartening.

Somehow these anemones are able to tolerate the presence of sand on their tentacle surfaces. With hope, it is possible that the northern sand bar will be home to even more of these anemones. This may probably help Chek Jawa return to its former glory where there are so many of these carpet anemones on the sand bar.

Other than those found on the sand bar, there are also many carpet anemones living within the lush seagrass meadow.

Many of these carpet anemones among seagrasses and seaweeds look healthy based on their coloration. We are glad to know that these creatures survived some extreme weather conditions, especially in January this year when there were heavy rainfall.

I only saw a small number of Peacock anemones (Order Ceriantharia) during this trip. I think it is because of the really hot weather that day.

Not sure if it is because the tide was not so low or that the seagrass meadow has shifted, there wasn't much of the southern sand bar exposed further away from the boardwalk. As such, I did not encounter many Cake sand dollars (Arachnoides placenta) in the south than in the north.

But as usual, at locations where these sand dollars are found, these echinoderms aggregate in large numbers.

Also due to the hot weather, I could only find a few of these Plain Sand stars (Astropecten indicus) which can be found in great numbers especially below dawn or after dusk.

A couple of the Common sea stars (Archaster typicus) were found near the southern sand bar. However, I did not see more of them elsewhere. Will they be able to procreate more individuals successfully to recolonize the sand bar as like before the mass flood? Only time will tell.

The sea cucumbers were well represented during the trip. There are about 7-8 different species found in this photo collage. The presence of these soft bodied invertebrates indicate that the salinity is within tolerable range.

Near the floating pontoon, I came across mats of what looks like that belonging to the Asian date mussels (Musculista senhousia). But after checking it out, I realize there were no bivalves inside the mat. I wonder what this is.

With the help of volunteers, Nparks has consistently been giving guided walks to the public to share the natural wonders of Chek Jawa with everyone. Kudos to their hardwork in raising awareness of the shore which we all love and would want to preserve.

I do agree that the ecosystems in Chek Jawa are indeed dynamic. Especially in the shifting in zonations of the sand bar and seagrass meadow. The button snails have gone MIA again. I believe it is probably a seasonal thing as they will migrate into deeper waters at certain stages of their life cycle.

Let us just continue to keep a good watch at this precious living shore.

More of what I've seen during this trip in my God's Wonderful Creation blog.