Aug 3, 2007

A look at Chek Jawa

This morning (not TOO early), Marcus and I joined Kok Sheng on his project to monitor the recovery of Chek Jawa. It was a chance for me to focus on looking carefully at Chek Jawa.

We started at the shore near the beacon. The shore was covered with lush growths of seagrasses, including the pretty Fern seagrass (Halophila spinulosa) and lots of seaweed (Caulerpa mexicana). The green marine meadows were studded with lots of living carpet anemones (Stichodactyla haddoni) and peacock anemones.On the sand bar near the beacon, what a nice surprise! This looks like a fresh dugong feeding trail through Spoon seagrass (Halophila ovalis) because the seagrass hasn't grown back yet.And another nice surprise. We bump into Sponge Expert Swee Cheng who is accompanied by Chee Kong. They are here to do a survey of sponges. Alas, there were NOT a lot of sponges. Some were growing back, but not in the numbers and bewildering variety that we used to encounter.

We wandered on and what is this!? Could this thing in the sand be the first Common sea star (Archaster typicus) to be seen since the big flood early this year wiped them out? We thought so at first and took lots of photos.Cheh! It turned out to be a brittle star instead.

Kok Sheng later pointed out an area covered with brittle stars! Not something I've commonly seen before on Chek Jawa.We also saw lots of tiny little Sand stars (Astropecten sp.), and I saw one medium sized Biscuit star (Goniodiscaster scabra).The sand dollars were doing just fine. They were everywhere in large numbers and all sizes.We also saw what looks like a small Sandfish sea cucumber (Holothuria scabre). These sea cucumbers were wiped in large numbers during the flood. So if it is one, that's a nice sign of recovery.

As we headed out to the Northern sandbar, we came across a rather small Armina babai. A burrowing nudibranch that we've only seen so far on Changi.Later on, Marcus found this hirsute sea hare, it was all alone. It might not be the normal Hairy sea hare (Bursatella leachii). It may be something else altogether. We're not really sure.Being in an anemone mood all week, we also kept a lookout for them 'nems. We saw two swimming anemones, and one of these anemones with lines along their tentacles that we've seen also on Changi.On the way back, we also checked out the tiny pretty striped sea anemones on the boardwalk legs, and the little brown blobs in the rock pools.In the coastal forest, the Delek air (Memecylon edule) trees were blooming! What a spectacular sight!
Several encounters were thought-provoking today.

Approaching the Northern sand bar we realised the shore was covered with large mounds. A closer look reveals they are mussel beds. The little animals are probably Musculista sp. which build communal 'nests' out of byssal threads incorporating sediments, bits of broken shells and other debris. The nest is pockmarked with little slits, each housing one mussel.

Nothing much else is found on the mounds. Seagrasses don't grow on it, there are a few hermit crabs perched on top of the mounds and a few whelks (Family Nassaridae) that are found in the fringes. But the mounds do create pools that are filled with darting fishes (impossible to shoot), crabs and other small creatures.

Later on, we realised the beds extend the entire tide line along Chek Jawa, all the way towards the boardwalk. In fact the mussels were also settling on the boulders near the mid-water mark!We're not really sure what this change means.

Alas, as we checked out the Northern area, we came across an abandoned drift net. In it were trapped four large horseshoe crabs and four swimming crabs. Swee Cheng and Chee Kong patiently released the crabs, while Marcus documented the event. We put the trapped creatures into a nearby stream and they seemed alright.
At the end of our trip, Swee Cheng and Chee Kong took the entire drift net all the way to House No. 1 so that it would no longer harm any other marine life on Chek Jawa.
Another disturbing thing we noticed was a great deal of rubbish on Chek Jawa. I noticed it first when I arrived near the beacon. The low water mark was littered with not only natural materials such as floating mangrove seedlings, but also a lot of styrofoam bits, plastic beverage bottles, used noodle containers, snack packaging, even a tube of sunscreen. The same line of litter continued throughout the shore to the Northern sandbar, mostly used food containers.

Kok Sheng has a photo of a styrofoam noodle container with left over noodles in it! He also shares some other related issues on his chek jawa project blog as he urges us not to spoil the Chek Jawa recovery.

I have been going to Chek Jawa for many years and have not encountered litter in such quantities before. The only time I see this amount and this kind of litter is on the East Coast, and to some extent, at Changi as well. Could this be litter tossed by people from the boardwalk? Certainly, before the boardwalk was opened, I didn't encounter such a situation.


Goh Pei Hao said...

The rubbish situation looks weird, something i never see before either. Hmmm...

Sivasothi said...

I've seen the rubbish float in like this before.

Liana said...

i'm guessing the spread of the mussel beds could be due to a lower sea star population than usual.

Ria Tan said...

Thanks Liana, that's a good thought to follow up on. Siva and Dr Dan will be at Chek Jawa tomorrow, I'll ask them.

About the rubbish, I guess it's 'good' to know it's not something totally new? Thanks Siva.