Saturday, July 4, 2015

Annual survey at Chek Jawa's coral rubble

Chek Jawa is a special place in many Singaporean's heart. We almost lost this shore to development more than 10 years ago and are heartened to know that it is still around today for many to enjoy and appreciate. For me, it is my first field site as I did my UROPs project in 2007 studying the mass mortality and recruitment of organisms.

Today, the shores of Chek Jawa are out of bounds to the public to prevent trampling and one needs to follow a guided walk to go down and see the richness of the marine habitat. Thanks to permission from Nparks, a group of us were able to do an annual survey of the coral rubble at Chek Jawa this morning.

How is the coral rubble doing? This was one of the habitats that was hit most during the mass death event in 2007. Today, we see the coral rubble very slowly coming back to life.

One can still find hard corals, soft corals and sponges interspersed around the entire area. However the sponge count seems to have dropped since mid of last year.

Most of the hard corals that we can find would be the Pore hard corals (Porites sp.). All of them are doing well and are not bleaching.

I also came across a colony of Disk coral (Turbinaria sp.) and Boulder sandpaper coral (Psammocora sp.).

A special hard coral sighted would be this Grooved brain coral (Symphyllia sp.), probably Symphyllia recta. Many thanks to Danwei for the id! I believe it's our first sighting of the brain coral in the north!

Another hard coral-related special find would be these two slugs found feeding on the Pore hard coral! And that is the reason why some of our corals are greyish-blue as it is a result of being fed on. 

Here's the underside of the slug, where you can still find some remains of what the slug has been feeding on.

Thanks to Chay Hoon for the id, this aeolid slug is likely Phestilla lugubris. It's our first time seeing it on our intertidal shores. As mentioned on the Sea slug forum, they are probably much more common than realised, it is very cryptically coloured and often hidden in crevices and beneath the coral blocks to avoid heavy fish predation.

Another slug that we saw, which is definitely not cryptic in nature would be this flamboyant Blue dragon nudibranch (Pteraeolidia ianthina). The scientific name of this slug is currently being reviewed.

Despite having less sponges on the coral rubble, something worth celebrating would be many of these Flowery soft corals (Family Nephtheidea) that have grown to occupy a small stretch of the coral rubble. This reminded us of Tuas!

Another consolation would be these Barrel sponges (Xestospongia testudinaria) that seem to be doing well! Though they are common on pristine reefs in the southern reefs, we hardly see them on our northern reefs.

Moving on to sea stars which are my favourite, I was delighted to find about 5 of these majestic Knobbly sea stars (Protoreaster nodosus). The one on the bottom right of the collage was found on seagrass!

What was encouraging would be the presence of this young Knobbly sea star which shows that the population is still growing.

The Biscuit stars (Goniodiscaster scaber) are the most abundant on our survey today! They can be both big and small. And here we have a photobombing Fan-bellied filefish (Monacanthus chinensis).

There was even a six-armed biscuit star that Rene found on the shore!

I later also found a six-armed orange Cake sea star (Anthenea aspera)! Cake sea stars come in different colours and patterns.

At first I thought this was a Scaly sea stars (Nepanthia belcheri) but actually it is a large Crown sea star (Asterina coronata)! In fact it is the largest crown sea star I've ever seen.

Missing from our northern shores for some time would be the Estuarine seahorses (Hippocampus kuda). I am glad to find one on our trip today!

This master of camouflage is known as the Velcro crab (Camposcia retusa). It is named as a Velcro crab as it has the ability of the velcro to attached bits and pieces of stuffs on its body so that it can be well camouflaged with the surrounding, especially when motionless.

This brightly coloured and large hermit crab is known as the Spotted hermit crab (Dardanus sp.). We seldom see them on our northern shores.

Another uncommon critter of the north (though very common in the south) would be this Frilly sea anemones (Phymanthus sp.). I only saw one today.

The Snaky sea anemone (Macrodactyla doreensis) is also uncommon on our northern shores. They are named snakey anemones because of their snake-like tentacles that tend to curl.

Close to the end of our survey, we noticed the imminent weather approaching from the west. Therefore we have to quickly evacuate before we get hit by the storm. Let's hope Chek Jawa will continue to remain and thrive for a long time.

More photos of the trip on my facebook album:

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