28 July 2010

Oil-slicked Tanah Merah: Still full of stars!

Today we check out the Tanah Merah lagoon that was first hit by crude two months ago, and one month after our last trip here.
There's still crude on the shore, and grey muck under the sand, slick on the water, but the sea stars are still alive and mating!

I saw more than 100 Common sea stars (Archaster typicus) today! I was worried that they might be affected by the spill, so started taking photos of every single one that I came across. But I stopped after it became obvious that they were still abundant. After stopping, I continued to see many of them. When I got home I counted them: there were 102 sea stars in my photos. Here's some of them.
I photographed a total of 21 sea stars in mating position. Here's a selection of them.
In addition, there were pairs that were very close to one another. Perhaps getting ready to get into the position? I saw most of the sea stars at the mid-water mark where they usually gather. Alas, this 'gathering area' was full of grey muck and coated with a thin film of crude (the brownish scum in the photos).
I don't know how the sea stars cope with the grey muck that is found just beneath the thin top layer of sand. You can see this muck in the imprint left by this sea star that is moving.
Besides having to cope with crude on the shore, the poor mating sea stars also have to avoid being suffocated by litter on the shore. Sigh.
Several other kinds of animals were also still abundant on the shores today. Such as the prawns (Family Penaeidae) which were very lively in the shallow lagoon left behind at low tide. Most that I saw were small or medium sized.
I also saw countless small Flower crabs (Portunus pelagicus) skittering all over the lagoon bottom. I only saw a few adults.
I saw many medium sized flower crabs with their butts in the sand facing up. They did not burrow into the sand as I approached. Then I realised that these were all empty crab moults!
There were lots of little fishes of all kinds in the shallow waters left behind at low tide. Some were very very small. Others just moved too fast for me to photograph and identify. Those I managed to take a closer look at included the ever present Shadow goby (Acentrogobius nebulosus), a small rabbitfish (Family Siganidae) and several halfbeaks (Family Hemiramphidae).
I only had a brief look at the rock wall and the corals and fishes there. It was tricky to get near the wall. As we step into the water, the underlayer of grey muck cloud up the water making it difficult to look out for Mr Stonefish. Also, the soft ground made it treacherous to keep our footing. Still, from afar, I saw a few coral colonies and they were unbleached.
There was one small live and seemingly healthy Acropora coral (Acropora sp.) colony.
I got glimpses of some of the large fishes that we often see sheltering in the rock wall. Chay Hoon also saw a baby seahorse! Alas, we didn't find any of the adult seahorses that we saw in the past.
A pair of Pencil squids (Family Logliginidae) swam slowly by before disappearing into the murk that I created as I stepped into the water.
A small Blue-spotted fantail ray (Taeniura lymma) zoomed from the murky water into the rock wall.
There were many Nerite snails (Family Neritidae) out and about on the rocks. My first time seeing so many after the oil spill.
I spent most of the time away from the rock wall, on the shallow lagoon bottoms. The shore was quite bare of seaweeds! There were only small clumps here and there, and no green seaweeds. These are some that I saw today (from left): Gracilaria salicornia, Acanthophora sp., Soliera robusta, Padina sp., Sargassum sp., and pom pom red seaweed.
The Bazillion snails (Batillaria zonalis) are not so abundant in this lagoon, compared to the other Tanah Merah lagoon. But there are clusters of many of these snails in the more rocky parts of the lagoon bottom.
Most of the other animal sightings were of single or a handful of animals. I saw one small Haddon's carpet anemone (Stichodactyla haddoni). Stephen saw a peacock anemone (Order Ceriantharia) and one Synaptid sea cucumber (Family Synaptidae).
I saw one adult Horn-eye ghost crab (Ocypode ceratophthalmus) and three young ones which were so small that they had yet to grow the 'horns' on their eyes. I didn't see any Sand bubbler crabs (Scopimera sp.) in the area where they used to be. And I didn't see any Moon crabs (Matuta lunaris) either.
I saw two live Gong gong snails (Strombus canarium) and one of them seems to be laying an egg string (see the tangle of very thin filaments infront of it?).
I saw one live moon snail (Polinices mammatus) burrowing in the sand.
I saw one cluster of Button zoanthids (Zoanthus sp.) and one clump of blue spatula sponge (Lamellodysidea herbacea).
I only saw three Acorn worms (Class Enteropneusta) and only one had a good 'pile', the others producing only a shallow 'hill' of sediments. I also saw one Peanut worm (Phylum Sipuncula) above ground. Oh dear. This might mean that something is going on under the sand that disagrees with these burrowing worms.
There were a few patches of Spoon seagrass (Halophila ovalis) but all the leaf blades were completely covered in scum.
I saw two clumps of Tape seagrass (Enhalus acoroides) both with sparse leaf blades. One clump was entangled by abandoned rope. Sigh.
This enormous bird footprint shows that the herons are still foraging in the lagoon.
Many parts of the shores are still very soft underfoot. Here's a photo of where my foot suddenly sunk in showing the grey scum that emerges from under a thin top layer of sand.
There were many dark patches on the sand which were coated with some kind of white fuzzy filaments that resemble fungus. I have no idea what this is.There are still 'pancakes' of crude on the low water mark, slowly becoming covered in sand.
Just beneath a very thin layer of sand, the crude seems as glittery fresh as the day it landed on the shore two months ago!
Here's another 'pancake' of crude, leaking 'sheen' onto the shore.
Large slicks of crude still form on the water all over the lagoon.
The plastic litter below the low water mark are coated with crude.
The usual pile of floating debris has accumulated in the usual corner of the lagoon. Fortunately, the litter doesn't seem as badly slicked as those trapped below the water line.
While it was heartening to see so many sea stars still alive on the shore, as well as many prawns and shrimps and flower crabs, the diversity on the shore is definitely much less than that seen on our previous trips.

Tomorrow we check out another oil-slicked lagoon at Tanah Merah.

More on the Oil Spill facebook page with links to posts and photos about checks on oil-slicked shores and other background on the spill since it first happened.

More about my previous trips to Tanah Merah.

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