27 June 2009

Checking out the Chek Jawa coral rubble area

Today I was out with TeamSeagrass at a super low tide. I took the opportunity to check out the coral rubble area at Chek Jawa. I've been visiting this area for nearly a decade now and it has a special place in my heart.
This photo was taken in Jul 2002, long before the boardwalk was built. As you can see, the area was rich in sponges and other marine life!

Unfortunately, Chek Jawa suffered mass deaths in early 2007 which wiped out the sponges and other marine life. Read more about this incident and the effort to document the recovery in Kok Sheng's Chek Jawa Mortality and Recruitment Project blog.This is what the area looked like today. There were very few sponges. Whereas in the past, almost every bit of coral rubble was covered in encrusting animals, today there were only a few of such instances. This patch of bright orange ascidian with an orange sea cucumber was seen near the beacon.
This patch was on the sand bar between the Beacon and House No. 1.
This patch was seen under the jetty near House No. 1.
But there were clumps of sponges here and there. Just not a jammed packed mess of sponges as it used to be.
There seems to be enough sponges to support quite a population of these Denison's nudibranchs (Dendrodoris denisoni). I saw four of them today, in various sizes.
Including this small one among the seaweeds. This nudibranch eats sponges, possibly sponges that live in murky, mucky sites. It lacks a radula and jaws so it can't rasp or chew its food sponge. Instead, it secretes digestive juices onto the sponge and then sucks up the softened sponge.
Other molluscs that were active were the Noble volutes (Cymbiola nobilis). I came across two of them laying eggs, and this big mamma who has done a great job.
I also came across a really tiny octopus.
It released an ink that retained a shape quite similar to itself, before settling into its burrow and changing colours to match its surrounding exactly!
A little further along, I came across one that was stranded and had turned pale. It'll be alright when the tide comes in, I'm sure.
What was really surprising was to come across several colonies of hard corals!
Some were quite large (about 30cm across).
Others were smaller. A closer look at the corallites suggests they might be Pore boulder corals (Porites sp.). I've seen these on Chek Jawa before, so it's nice to see them making a comeback.
Most of them seemed to be doing well, although one had a corner that was bleaching.
There were also small colonies of the super tough Zebra corals (Oulastrea crispata).
Sometimes mistaken for hard corals are these mounds of Button zoanthids (Zoanthus sp.). There were several of these, but not in overwhelming numbers, on the coral rubble area today.
A first encounter on Chek Jawa was several large groups of these fine feathery soft corals. I've seen these in numbers at Tuas, Beting Bronok and many of our Southern Islands. But I don't recall seeing them on Chek Jawa before. Does it mean Chek Jawa is becoming 'reefier'?
This pink flowery soft coral (Family Nephtheidea) is often seen on our Northern shores and also on Chek Jawa. It was nice to see a small colony today. But I didn't see any animals living in it.
On the beacon legs, there were the remains of several dead sea fans, and one tiny colony of pink sea fans that resemble trees. I wonder why we see so many more sea fans on Changi (see Kok Sheng's post) and even the East Coast than on Chek Jawa? Perhaps they grow in deeper waters at Chek Jawa? Hmmm.
With Dr Daphne's upcoming trip, I'm particularly focused on checking out the anemones on our shores. Today on Chek Jawa, I saw one Swimming anemone (Boloceroides mcmurrichii) and several of these dusky pink Posy anemones which are very common on Pulau Sekudu.
Of course, there were lots and lots of Haddon's carpet anemones (Stichodactyla haddoni) and they all seemed to be doing well. Except for this one which seemed a bit yellowish. Perhaps due to the very hot weather? I get very nervous nowadays with off colour carpet anemones as these may be an early sign of ill health.
And then, I came across this large blob (about 6cm across), with some tentacles sticking out of its mouth. It's definitely a sea anemone but I have no idea what it might be!
Here's a closer look at the tentacles and body column. The only sea anemone I've seen that comes close to it is the Haeckel's anemone (Actinostephanus haeckeli).
It was nice to come across some small Knobbly sea stars (Protoreaster nodosus). There were two of them in the coral rubble area today.
There were, however, lots of Biscuit sea stars (Goniodiscaster scaber). Many of them were large (about 10cm from arm tip to arm tip).
It was nice to see several of the orange sea cucumber. I also saw a smooth sea cucumber half buried in the sand.
Here and there were fluffs of fan worms (Family Sabellidae).
The seagrasses at the coral rubble area were doing very well indeed. I've posted about this on the TeamSeagrass blog.

Today, there were lots of people at Chek Jawa because there was a guided walk on. It was nice to catch up with some old friends and also to see so many people enjoying Chek Jawa.

A group of people had snuck out to the shore near House No. 1. They took a few photographs of birds feeding on the shores and then headed back to the trail.And there was an old abandoned net on the shore which is already well overgrown with seaweeds. I didn't see any new nets or traps on the shore.
I feel the coral rubble area is doing well, although of course, I had hoped for better. With time perhaps, it will regain its original splendour.

Other posts about this trip


  1. What a big difference between your first picture and 2nd picture,very impactful pictures. With so many people like you putting in so much effort and time in conserving our shore, I hope the place will return, at least partially, to its good old days, teeming with all sorts of marine lives.

  2. Thanks for sharing your wonderful discoveries : )

  3. Thanks Federick and Joe for the encouragement. Yes, I'm sure with time Chek Jawa will be her old self again.



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