Jul 4, 2008

Sekudu Survey

3am and a small team were off to check out Pulau Sekudu which lies just off Chek Jawa. The island is now part of the Chek Jawa Wetlands and requires a permit to visit. We were eager to see how this added protection would have affected the marine life there.

The seagrasses were doing well, with lots of healthy carpet anemones of various sizes. Tiny sea pens were seen, although the more common ones with the orange 'root' were not encountered.There were little sand stars among the meadows, as well as a few white sea urchins (Salmacis sp.) and black sea urchins (Temnopleurus sp.).This is my first time seeing the black sea urchin on Sekudu. However, we didn't see any pencil urchins (Prionocidaris sp.) this time around.

It was generally 'quiet' compared to earlier visits. Most of the coral rubble was bare, until the tide fell very low. It was only then that the kind of sponge and encrusting growths that we used to see in the past were revealed.
Sponges are not only pretty but also provide places for animals to shelter. Like this bunch of many little hermit crabs.I have no idea what kind of hermit crabs these are.

Nudibranchs also feed on such encrusting animals and thus more common where there are good growths. So happily, Chay Hoon finally found her nudibranchs after going slugless for two days of field trips.

The coral rubble was infested with the little brown sea anemones that used to be common but disappeared after the flood of 2007.These little sea anemones are not only back, but I also noticed that there were green ones among the brown ones too! Are they just different coloured versions or entirely different kinds of anemones?

We looked for Knobbly sea stars (Protoreaster nodosus) and altogether we saw five. We also saw several Biscuit sea stars (Goniodiscaster scaber). But all these stars were adults.

It's good to know that at Changi yesterday, we saw lots of baby sea stars. Lying just across from Pulau Sekudu and Chek Jawa, Changi can be a source of new recruits should anything happen to these Ubin shores.

Chay Hoon found this four armed Crown sea star (Asterina coronata)!
Jeff annouced happily "Didn't you know Ria, fore warned is for armed?"... groan.

Our trip was disrupted for a while by a rain shower, so we didn't really explore thoroughly. Some parts of the shore was thick with stinging hydroids, but I could only find one of these beautiful pink soft corals.On our visit last year, we encountered canoeists who came to Sekudu to remove these soft corals. Let's hope the new measures in place to restrict access to Sekudu will reduce such losses.

Among the special encounters was this pretty moon snail.We've seen this moon snail on Changi too and a kind reader suggested it might be Tanea euzona.

Dr Chua found this amazing sand dollar! First one, then another!It was pink! This might be Peronella lesueuri which is listed in Dr Lane's book (Lane, David J.W. and Didier Vandenspiegel. 2003. A Guide to Sea Stars and Other Echinoderms of Singapore. Singapore Science Centre. 187pp.) According to the Guide: "This species is not common in Singapore waters. In recent years, it has been dredged only south of the mainland and then only occasionally."

But the most stunning encounter for me was Nemo of the North!Originally thought not to exist on our Northern shores, I was quite surprised to find this False clown anemonefish (Amphiprion ocellaris) on Pulau Sekudu!

Unfortunately, clown anemonefishes have been harvested from the wild for the aquarium trade. So much so that they may become locally extinct. Here's more about the situation in Australia. Let's hope this little Nemo and her friends on our other shores are left alone in the wild.

Although there were fewer fish traps on the shores compared to our last trip, we saw an abandoned driftnet stuck among the rocks.We also saw a fisherman lay a drift net in the channel between Pulau Sekudu and Chek Jawa. I hope all these dangers will not hurt Nemo and all the marine life on this precious little island.

More about encounters on this trip on Kok Sheng's wonderful creations blog.


Anonymous said...

This was my favorite fishing ground! I don't think I like this kind of blog who using it like a tool!

Anonymous said...

Your Salmacis sp. is likely to be
Salmacis sphaeroides (Linnaeus, 1758)

But Salmaciella dusummieri (L. Agassiz, 1846) is propably the nearest congener.

Not too sure of the one on the right.

Quite common around Changi to East Coast and was wondering why Dr. Lane didn't have it in his "A Guide to Sea Stars and other Echinoderms of Singapore.

Keep up the good work. Thanks.

Ria Tan said...

Thanks yy for sharing that!

I'm not sure why Dr Lane didn't include it in his book. We'll be sure to ask him the next chance we meet him.