25 June 2010

After the oil spill, stars still out at Tanah Merah!

With trepidation, we visited this other sector of Tanah Merah dreading what we might see.
So it was most heartening to see that many sea stars are still very much alive on the shore!

We must have seen about 30 of these Common sea stars (Archaster typicus) today. They were more spread out than usual, with more seen near the low water mark than usual. I didn't see any other echinoderms dead or alive.

When we last visited this shore, it was a month ago, a few hours after the spill hit this shore. Although we notice many signs of crude still on the shore, the hard and soft corals growing on the sea walls seem mostly alright. And this is the first time I noticed a leathery soft coral growing here! It's the pinkish colony at the lower right corner of the photo.
The most abundant hard coral here are Zebra corals (Oulastrea crispata) which is the most widespread coral in Singapore and can be found in murky waters. Like elsewhere, they grow in small encrusting patches on hard surfaces.
Oh dear, some of these tough corals are starting to bleach.
There's a variety of other hard corals growing here too, mostly Pore corals (Porites sp.) and Favid corals (Family Faviidae).
There are also many tiny baby coral colonies starting out on the rocks. Some of them are not doing too well.
There are several large Pore coral (Porites sp.) colonies here, and those I saw were not bleached.
This Pore hard coral, however, seems to be starting to bleach.
So too, this large colony of Favid coral.
While this looks like a hard coral colony that has bleached and died as it's already covered in scum. Possibly a Cauliflower coral (Pocillopora sp.) which we already saw bleached on our last trip.
There are a few colonial anemones or zoanthids (Order Zoanthidea) and they seemed alright.
The Haddon's carpet anemones (Stichodactyla haddoni) were mostly still unbleached. And look, there are living prawns (Family Penaeidae)! I saw a few, but not as many as in the past.
Here's some other Haddon's carpet anemones I saw.
I only saw one bleached and distressed carpet anemone. It took me a while to figure out what this was.
And I saw this small anemone that was completely bleached. I'm not sure what kind of anemone it is exactly, possibly a Tiny carpet anemone (Stichodactyla tapetum)?
It was heartening to see some crabs on the shore. I saw one Moon crab (Matuta lunaris) and many active Horn-eyed ghost crabs (Ocypode ceratophthalmus) both young and adults, all clean of crude. There were also many swimming crabs (Family Portunidae) of various kinds and sizes from tiny ones to large adults. When we last visited, we saw many dead and dying Moon crabs, and many of the Ghost crabs were covered in crude.
I even came across this pair of Flower crabs (Portunus pelagicus) that seem be in position for mating.
How nice to see the Spotted hermit crab (Dardanus sp.) on this stretch of Tanah Merah too. However, I didn't see other kinds of hermit crabs.
I saw several living Gong-gong snails (Strombus canarium) their shells without obvious signs of crude! But not as many as in the past. These snails were badly distressed on our previous trip here.
A closer look and there's fine coils egg strings in front of this snail. Is it laying eggs?
Other living snails seen on the shore including one Dolphin shell snail (Angaria delphinus), a large Spiral melongena (Pugilina cochlidium) and many whelks (Family Nassaridae). I saw several living Oval moon snails (Polinices mammatus) on the sand and one Nerite snail (Family Neritidae) on the rocks. We couldn't find any live Button snails (Umbonium vestiarum).
We saw a few Acorn worm casts. The only fan worm (Family Sabellidae) I saw seemed to hesitate about sticking its fan out of its tube. We did not see masses of distressed worms on the shore as on our previous trip.
Other creatures seen include a few sponges that didn't look very good, one Thumbs up sea squirt (Polycarpa sp.) and one Slender sea pen (Virgularia sp.).
I came across patches of VERY tiny Spoon seagrass (Halophila ovalis) with even tinier fishes nestled among the leaf blades. The ground just beneath the sandy surface where the seagrasses grew were black and soft, silty mud-like.
Today we saw much fewer fishes than on our previous trip, when many distressed fishes were outside their hiding places. In larger shallow pools there were more gobies (Family Gobiidae). But not many gobies in smaller pools. I saw much fewer surface dwelling fishes than I usually do here.
I did see this large black fish that is commonly encountered hiding in spaces among the rocks. I'm not sure what it is, possibly a grouper or damselfish.
But it was very hard to survey the deeper water because the ground has turned soft and slippery with a silty mud-like substance, resulting in mucky water with every step. More on the signs of crude seen today.

It also did not help that it was also constantly drizzling, in a strong wind.

There were only two of us doing this survey at the 3am low spring tide. So we only covered a very small area. We also cut short our trip as lightning started to play up and we could sense heavy weather coming in.

We need to survey this shore regularly and hope for the best.

See also Chay Hoon's post about our trip.

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