12 July 2010

Checking Changi for oil spill effects: cucumber suprise!

This is our first visit to a rich stretch of Changi that was hit by the oil spill seven weeks ago. Sam visited the shore the day after the spill and found things to be alright. But we worry about long term effects.
So it was a relief to find the shore crowded with life. One of the highlights: this pair of these bright yellow Estuarine seahorses (Hippocampus kuda) that shared their little pool with other creatures.

Tucked between the seahorses were a little pinkish sea cucumber and the siphon of a buried bivalve, possibly a Razor clam (Family Solenidae)! It sure is crowded! Chay Hoon also saw seahorses, but I'm not sure if she saw these same ones.
As usual, the pools of water shelter lots of little animals. Today, the seagrass pipefishes seem to be back in season with many encountered on our trip.
Like the seahorse, it is the papa pipefish that carries the eggs. This pipefish was seen upside down already and you can see the pouch under his belly. I placed him gently in a pool and he seemed alright.
On this shore, the peacock anemones (Order Ceriantharia) often have a ring of little black Phonorid worms (Phylum Phoronida) at their base. There were many peacock anemones on the shore today, with their worms. And also many large Striped hermit crabs (Clibanarius sp.). I noticed that many of the hermit crabs had drill snails (Family Muricidae) on their shells. Perhaps the drills are getting ready to lay their eggs there?
This shore is among the few places where we can find the beautiful Tiger sea anemone which has striped tentacles and a red-spotted body column. They were quite abundant today. There were also several swimming crabs (Family Portunidae) on the shore.
There were several large Haddon's carpet anemones (Stichodactyla haddoni) and the one in the photo seems to be in the process of either eating or spitting out a large crab!
Among the other animals seen in abundance today were many snapping shrimps (Family Alpheidae), lots of Flower crabs (Portunus pelagicus) of all sizes, many living Gong-gong snails (Strombus canarium), many small rabbitfishes (Siganus canaliculatus), lots of little gobies (Family Gobiidate) of all kinds and several flat-armed brittle stars.
Particularly abundant today were the Thorny sea cucumbers (Colochirus quadrangularis). There were lots of them, sprinkled all over the shore. Some were clustered together.
In fact, the dominant group on the shore today were sea cucumbers! Other sea cucumbers seen included many buried ball sea cucumbers (Phyllophorus sp.), many Warty pink sea cucumbers (Cercodemas anceps), many orange sea cucumbers, and some beige sea cucumbers.
I also saw many of these sea cucumbers. 5-10cm long, they are pale with rose to pink patches and very long tube feet. I don't know what kind they are and I've not seen so many of them before.
My favourite find was this sea cucumber that I've never seen before! It was about 12cm long and was hard and felt rather plasticky.
The sea cucumber was seen half buried in the ground. It had short, rather conical tube feet with bright orange tips, contrasting with the greyish blue body. I have no idea what it is!
This shore is usually rich in echinoderms. Unlike our previous trips, however, we didn't see many sea stars today. I did see one very young Cake sea star (Anthenea aspera) which still has long arms (it's the bigger star in the photo). And there were many small Biscuit sea stars (Goniodiscaster scaber), the small star in the photo.
There were some Sand stars (Astropecten sp.). I saw more Painted sand stars (left photo) than the usually more common Plain sand stars. But we didn't come across any special sea stars. Perhaps they knew Kok Sheng wasn't with us.
We came across a huge gathering of Black sea urchins (Temnopleurus sp.) covering an area of about 2m square! This is sometimes seen on Changi shores.
Here's a closer look at the fat and healthy looking sea urchins. These animals purposely carry shells and other bits of rubbish. Where they were clustered, there were mats of Nest mussel (Musculita senhousia). Do the sea urchins eat these little mussels?
There were also many cnidarians on the shores. I saw many flowery sea pens (Family Veretillidae), some near one another. They come in many different colours. But I only saw two Sea pencils.
There were several tiny carpet anemones which might be Stichodactyla tapetum. This one had a tiny shrimp on it!
I saw this buried sea anemone with a bright orange body column. I saw something like this on another stretch of Changi shore in 2007.
The only octopus I saw was a dead one. Sigh.
And the only slug I saw was this lone Geographic seahare (Syphonota geographica), although there were many pink egg strings which I believe is laid by this kind of seahare. Sometimes, there is a lot of these slugs on this shore, but not today. Chay Hoon, of course, found many more slugs.
Among the interesting crustaceans seen today was a bronzy-coloured spearer mantis shrimp (Harpiosquilla sp.) that zoomed about in the shallow water. I saw another one in the deeper murky waters in the more usual pale greyish green colour. There were lots of shrimps and small prawns too.
There was also this hermit with bright blue 'elbow' patches, colourful eyes and a scaly pattern on its pincers. This seems to be similar to the one Mei Lin saw at Beting Bronok. I believe Chay Hoon has got the ID for it and I'm sure she will blog about it.
We also check out the small stretch of rocky shore here and the Zebra corals (Oulastrea crispata) are still abundant and not bleached.
There were also a few purple branching sponges (Callyspongia sp.), and I saw two Crown sea stars (Asterina coronata). But the rocks are not very encrusted with marine life, with few banded bead anemones (Anthopleura sp.) and not many snails either.
The Spoon seagrasses (Halophila ovalis) growing on Changi often have very large leaf blades. Today there seems to be a little less of them, but still patches of dense growth here and there. Most of them seem alright, bright green and unbleached. There were also patches of Spoon seagrasses with small leaf blades. I didn't come across any Fern seagrasses (Halophila spinulosa).
Some patches of Spoon seagrasses however had yellowish or pale bases. And some had black leaf blades. But these blemishes were not as widespread as those we saw at Chek Jawa about a month ago.
Near the mid-water mark on the sloping sandy shore, I noticed a greyish layer under the sand. Fortunately Janette and her colleagues are monitoring this site for oil spill effects. We heard them hard at work later in the morning, but didn't get a chance to chat with them. I hope their work is going well.
Chay Hoon saw lots of other stuff, including a buried baby shark! Although we didn't see as many sea stars as before, there is an abundance of sea cucumbers today. And most of the usual favourites were still happy and active. While we saw some interesting finds too!

Another special today, there were no fishermen out on the shore. They were probably all watching the big soccer game. We could hear cheering throughout the morning from campers on the shore.

We enjoyed a glorious sunrise today! On the horizon to the left is Chek Jawa on Pulau Ubin and Pulau Tekong on the far right. The lights on the horizon mark the vessels at the mouth of the Johor River.
Let's hope this shore is truly unharmed by the oil spill.

More about the oil spill on wild shores of singapore and the Oil Spill facebook page.

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