04 July 2015

Soft coral garden at Chek Jawa

A garden of soft corals in pastel shades has settled at Chek Jawa!
The team conducts this survey of the Chek Jawa coral rubble area once a year. To see whether it has recovered from the devastating mass deaths in 2007 which wiped out the sponges and many other animals here.


I surveyed mainly the low water area outside the coral rubble area at Chek Jawa today. The abundance of Spiky flowery soft corals reminds me of Tuas Merawang beacon many years ago.
These colonial animals come in different colours. We started seeing them for the first time during our survey last year in Jun 2014.
These soft corals are home to tiny creatures such as transparent Little red-nose shrimps, Tiny colourful brittle stars. We could not find any Ovulid snails that usually feed on these soft corals. I didn't see any Ball flowery soft corals today.
The most abundant anemone on the coral rubble area were Posy anemones. There were also a few clumps of Button zoanthids. There were a lot of Haddon's carpet anemones, especially in the seagrass meadows, but also on the coral rubble area. I didn't see any that were bleaching. I only saw one Common cerianthid. There were a few small Flowery sea pens. And some clusters of Stinging hydroids.
There were also many small to medium-sized Pore corals, all those I saw were a healthy dark brown (not bleaching). This one seems to form a basket of sponges and other marine life.
I also saw two small Flowery disk corals. There were also many small patches of Zebra coral, some Neat hexa coral and small patches of Cave corals.
I also saw one colony of boulder Sandpaper coral.
I came across this small Estuarine moray eel. It wasn't really distressed and eventually wriggled to a bigger pool nearby and disappeared into a hole there.
I saw a small Blue-spotted fantail ray. The rest of the team saw other interesting fishes. Kok Sheng saw a seahorse. The first time we have seen one in the North for a long time.
Chek Jawa remains quite starry. I saw one Knobbly sea star (the rest of the team saw more). Also one Plain sand star, one Spiny sea star and several Cake sea stars. The most abundant sea star were Biscuit sea stars from small to large ones.
Perhaps it is because I focused on the very low water mark, I didn't see many of the sea cucumbers that we commonly see at Changi like the Thorny sea cucumber and Pink warty sea cucumber. I did see many Orange sea cucumbers, two Long black sea cucumbers (which are common in the Southern reefs). I also saw some Smooth sea cucumbers, Ball sea cucumbers, Garlic bread sea cucumbers. I only saw one White sea urchin.
There were a few sea fans at the edge of the low water mark, only Candelabra sea fans and Gnarled sea fans. Most looked alright. None had Ovulid snails in them. But I did see one with Tiny colourful brittle stars and another with Sea fan Winged oysters.
The diversity of sponges and number of sponges on the shore remains low. It is probably just as bad or worse than our survey in Jun 2014 which was already worse than what we saw in Aug 2013. The most common sponge was Melted chocolate sponge, the dark rose pink sponge that I have yet to figure out, and Yellow bumpy sponges. I did see the Thorny stem sponge, and there were two clusters of Yellow horn sponge. I saw several clumps of Purple branching sponge, some Golf ball sponges and Spiky ball sponges in various colours. Also clumps of black sponges.
Sponges also provide homes for many small animals. Such as these Sponge synaptid sea cucumbers.
We are glad to see sponges because many nudibranchs feed on them. Today I saw two of these Doriprismatica atromarginata nudibranchs that we commonly see on our southern reefs.
Nudibranchs lay 'egg ribbons'. These are eggs embedded in jelly and laid in ribbons that form pretty ruffled rings or rosettes. What nudibranch laid this? Does this nudibranch feed on the Melted chocolate sponge? What does it look like? So much more to discover about our shores.
Thanks to Jonathan for finding this beautiful Blue dragon nudibranch. It has purple rings on its tentacles near the mouth, and feathery rhinophores. The tubular things on its body (called cerata) are arranged like fingers on a hand. Chay Hoon says the scientific name of this nudibranch is being revised.
I was attracted to this because I saw the greyish patches on the lumpy Pore coral. I have seen these patches before and previously thought that they were caused by disease.
I took a closer look and realised there were nudibranch egg ribbons on the patch. And two suspicious brown 'hairy' things that looked like slugs. Chay Hoon confirmed that they are indeed nudibranchs, and these nudibranchs eat Pore corals! They are possibly Phestilla lugubris.
Here's a closer look at the nudibranch. And the greyish patch where it ate the coral.
There were lots of nice green Needle seagrass (skinny leaf blades), Fern seagrass, Spoon seagrass (big and small leaf blades). In the coral rubble area, I saw five clumps of Tape seagrass with cropped leaf blades, although the blades are quite long (about 20-30cm long).
I had a quick look at the Delek air trees, Critically Endangered trees found along the coastal cliff. Many of the leaves are curled up. And the flower bunches look odd. I'm not sure if the trees are ok.
The coral rubble area is only exposed at the lowest spring tides, which tend to happen before dawn. The lush seagrass meadows have grown close to and in some places taken root in the area. I sense the area has become shallower (more sand) and less silty. Fortunately, today we didn't come across any driftnets freshly laid on the shore. Although I came across an abandoned crab trap, and Juria saw some abandoned netting that look like fish farm cage nets.
We did expect a storm to arrive in the morning, having looked at the satellite maps for the region at the start of the trip. But it was still scary to finally see it arrive. Pei Yan giving the first warning of it looming over Pasir Ris. We hurried and managed to get back to safety in time before the wind, rain and lightning was unleashed.
The water in the Johor Straits looks alright. Not tea-coloured, which suggests a plankton bloom.
I last did this survey alone in Apr 2015 and with the team in Jun 2014.

Thanks to NParks for permission and support to do these predawn low spring tide surveys of Chek Jawa. Thanks also to Chay Hoon for making all the transport arrangements. And the team for helping to cover as much ground as we can during the narrow low tide window. Thank you!

Chek Jawa and Pulau Sekudu may be affected by the 2030 landuse plan by the Ministry of National Development. The plan includes plans for a road link (black line) 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.
Click on images for larger view.
I feel it is thus important to update our understanding of what is going on in the field at these sites including Chek Jawa and Pulau Sekudu.

Tomorrow, we will be surveying Pulau Sekudu.

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