Studying substrate variability in Chek Jawa by GIS

After collecting specimens of substrate along the transects last week, Yikang, Yong Jian and Jing Kai who are working on the GIS aspect of the substrate variability in Chek Jawa were back in NUS Geo Lab throughout the midterm break.


Studying sediments of Chek Jawa is no mean feat. It first involves scrapping off the collected substrate specimens onto a metal petri dish. Looks easy?


Here are the total number of samples they had to each test for substrate composition. And Yikang told me each bottle will take them 15-30minutes.


It was quite interesting to see different colours of sand and mud and other substrate types in different samples, which reflects possible wide variations.


As the sediments are wet, the team had to dry them at an oven for 15o degrees for half an hour. It's like baking cookies.


After which, the dried sediments of each sample will have to queue up to be sieved by this machine in the lab. Each sieving process takes 15 minutes. And all these work went on for four consecutive days before the manual processes were done.


On Thursday night, the team finally could enjoy the fruits of their labour. They displayed the results onto a GIS map where data interpolation can be peformed. We were pleasantly glad to see that there was some trends where the northern part of Chek Jawa has coarsest sediments. The mangroves end of Chek Jawa has the finest sediments. What caught my attention was that the sandbar "boomerang" shape was not visible in the map. That means that there are indeed more than one can expect when we predict the substrate variability in Chek Jawa.

Personally, I'm excited to see their analysis and they will be putting up a website soon to share their data and discussions. Let's watch out for it, I'll post it here too when it is up.

Reflections on Day 2 of February Transect

I was not able to be there on Day 2 of our February transect but the transect has to go on.


This is a photo showing Yong Jian setting up transect one on Day 2.


Day 2 is possible with Yikang who volunteers to help head the trip together with friends who volunteered. Yikang has written a reflection of that day of field work and I hope to share with you here.

"Today Kok Sheng is occupied with a lab session, so I have to kind of “take charge” of today’s transect session. I was a little anxious initially. But everything went smoothly thanks to the stellar team of Damien, Jingkai, Ria, Weilong and Yongjian.

Today was the first trip to Chek Jawa for Damien and Weilong, but they only took a while to get into the hang of things. Thanks Damien for volunteering and wish you all the best in your final year. I hope Weilong found the whole experience fruitful as he skipped two lectures to help out. Only got to know this today. Sorry Weilong didn’t get the opportunity to show you a sea star; couldn’t find sea stars that day in the area.

Thanks Yongjian and Jingkai for being so dependable and see you guys in geo lab. Another big thank you to Ria for covering me in T2 when I’m off video-ing T1, the mini guided walk, and the yusheng (which kind of reminds me of seagrass). Last but not least, thank you KS for the opportunity of doing useful work for the 'endangered' CJ that is close to our hearts."

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Below are more photos to share, from Day 1 taken by Yikang.


Adeline flaunts the datasheet while setting up the transect.


And all these require team work from volunteers. This is because the tide window is as short as 3 hours. Me alone will not be able to do all these.


Denise and Ron.


Siyang and Denise, chatting and resting as we finally completed the transect in time before sunset.

I would like to thank Yikang and the whole team for sacrificng your weekdays to do work on the shore. They did a wonderful job on day 2, ending the trip earlier than expected despite we were shorthanded.

The February transect trips conclude my field trips for my study at Chek Jawa and soon I will be doing analysis and writing of my report due end March.

Along the way, I will continue to share here on the progresses of the project. Do watch out for them.

February Transect Day 1

Time passes fast, and its time for the last series of transect for my study at Chek Jawa. This time, we are doing something special with the help of Yikang and his team. On top of doing our usual quadrat monitoring, we are also testing the sediment type of each quadrat location so as to better understand the substrate types of the study area.


On a sunny afternoon, friends from all over the place come together at Changi as we set off for Ubin. It was a weekday yet many took leave or special time off to volunteer for today's transect.


Arriving at the jetty of Pulau Ubin, we proceeded towards Uncle Chu's van. We also noted by the rocks by the sides of the jetty are covered with layers of mussel beds which has been persisting for quite some time.


Reaching Chek Jawa, we settled the logistics and off we went to the shore. As usual, July here is carrying the research in progress signboard which is important to inform the public of why we are down at the flat.


Day 1 of transect usually mean we will head north and finish the last 4 lines first. The greenish patch you see from this photos are the coverings of the algae on top of mussel beds.


After a mock up briefing, it was time to start setting up the transect line. And wow, this task was indeed challenging since the weather was extremely windy. The lines were easily blown aside and setting a straight line means lots of tug of wars.


Nevertheless, the garang team managed to set quite decent lines with the aid of the huge colour flags that ensured line of sight from the start points to the end points that were permanent. After a few rounds of trying out, most of us managed to figure the best way to lay lines with the windy condition, and hope these improvements can be of great use for day 2 later.


Meanwhile, while working, lots of Lesser-crested terns (Sterna bengalensis) can be found feeding and resting at the tip of the sandbar.


They are very shy, like most birds, and will fly off when I tried coming closer to them.


Flying higher and higher.


The tide was not very low but thankfully just sufficient for us to conduct the transect.


Unfortunately, Chek Jawa is too big to be sampled with justice over a short tide window period. This photo shows an example of a non biased sampling method that may not capture the animals we want. This carpet anemone was just a few centimeters away from our designated quadrat. If we just put the quadrat showing the carpet anemone, it will be biased.


Some of the other animals found include this small clump of mussels stick on the sand substrate instead of the usual hard ones.


These sandfish sea cucumbers usually start appearing when evening comes.


The seahare season was not over yet, and many of them can still be spotted.


Chek Jawa also is home to a rare seagrass, Halophila beccarii which was named after the intrepid Italian botanist-explorer, Odoardo Beccari.


More marine creatures: sea cucumbers, razor shell and sandstars.


Amazingly, I spotted a few dugong feeding trails like how Teamseagrass saw them during the mass death last Jan 2007. Dugongs are still present around Chek Jawa waters and indeed seagrasses are important food staples for them. It's fascinating how these trails appear during the mass death as an encouragement that life goes on and now towards the end of my study, Chek Jawa is indeed doing well recovering.


The teams worked hard and I am deeply thankful for their effort. This is one of the two teams with Denise, Ron, Siyang and Yong Jian (left to right).


Also, not forgetting to mention Pui San, Adeline, Jing Kai and July from the other team.


Here we have the geographer, Yikang, doing the sediment collection from the quadrat sites.


That involves digging out of a thumb size of substrate, which then we will bring back to the lab to test. More work.


Soon, the sun sets and it was time to leave.


Here's a last photo of July pointing to something in the cloud.

One more day to go...