02 June 2010

How's Tanah Merah doing after the oil spill?

Today, a small team revisit Tanah Merah about a week after the oil slick first hit this shore.
The corals seem mostly to be doing fine. The water is clear, and not as yellow as on the day after the spill hit. Although comprising artificial seawalls and reclaimed sandy shores, Tanah Merah has an awesome reef!

Most of the spectacular hard corals grow outside the seawall.
Only Kok Sheng the Human Climbing Crab can negotiate this slippery tricky area to take this and other spectacular photos in July last year. Read more about it on his blog and check out his other posts about Tanah Merah as well.

The rest of us lack a death-wish and as usual, stay on the inside of the seawall. Even here, small to moderately large colonies of hard corals have settled on the artificial wall.
I only saw a few bleached coral colonies. Most of them were Pore corals (Porites sp.) with one Favid coral.
But many of the Pore corals seem to be doing fine.
There was one Flowery disk coral (Turbinaria sp.) that looked normal, and many patches of brown-as-usual Zebra corals (Oulastrea crispata).
There are many colourful colonies of Favid corals (Family Faviidae) of all kinds on this shore. They all seemed to be fine.
There were only a few patches of zoanthids. And they seemed to be normal.
I saw two Haddon's carpet anemones (Stichodactyla haddoni). Each looked normal and had a living anemone shrimp. One of the anemones was in shallow water and curled up. But this is probably because of the rain. Intertidal marinelife don't really like lots of freshwater. The other one was in deeper water. Both were not bleached.
The reef fishes were behaving normally this morning. As usual, on a daylight trip, they are well hidden. I saw a few zooming about from one hiding place to another. The only fishes I managed to photograph was this school of tiny fishes swimming about energetically.
There were no lethargic fishes as I saw on my trip a week ago. And I didn't see any dead fishes. But Grace found a Blue-spotted fantail ray (Taeniura lymma) trapped in a pool, something we've encountered before. It seemed fine.
And I spotted a well camouflaged Painted scorpionfish (Parascopaena picta) that seems alright.
A Spotted scat (Scatophagus argus) was also stranded in a pool, also something we've encountered in the past. It seemed quite lively.
There are fewer but still some gobies in the shallow pools. Today I saw an Ornate goby (Istigobius ornatus) and the very tough Shadow goby (Acentrogobius nebulosus).
I did see a recently dead squid, it still has its colours. Marcus saw one still leaking ink. In the past, at night, I am sometimes besieged by schools of these charismatic creatures.
There were many crab shells on the shore. But not all of them are dead crabs. In fact, those I looked at turned out to be crab moults, like the one in the photo below. Crabs (and other crustaceans) moult or shed their skin, including all hard parts exposed to the water like gills and mouthparts. So a badly oiled crab can survive by shedding its oil-coated skin? I also saw a few lively small Flower crabs (Portunus pelagicus).
Among the Missing in Action creatures are the crabs of the high shore. Today I only saw a few burrows made by possibly the Sand bubbler crabs (Scopimera sp.) and Soldier crabs (Dotilla sp.).
There were a few Striped hermit crabs (Clibanarius sp.) on the shore. They were lively and slick-free.

It was heartening to see many coils of sand produced by Acorn worms. These worms apparently can grow quite long and are possibly deeply buried in the sand.
The acorn worms are most definitely still alive and we had glimpses of the butt-end of some worms. Some of the worm casts were dark, but we have seen this before in the past and doesn't necessarily mean that the sand is contaminated with oil. On many shores, the deeper layers of sand are black from the action of anaerobic bacteria. This is the same reason why mangrove mud is black, and is a sign of life rather than death.
How nice to see some living fan worms (Family Sabellidae), although they are not as 'fluffy' as usual.
Today I still saw some Peanut worms on the sand, most were still weakly alive. Though not as many as on my trip a week ago. These worms have been washing up on East Coast shores affected by the slick as well. So they seem to be more common and widespread than I first thought.
Today I didn't see many clusters of bristleworms on the sand as I did on my trip a week ago.

The Zoned horn snails (Batillaria zonalis) are still doing very well on this shore. They occur in vast numbers covering almost the entire shore, as usual. Among them, also countless Dubious nerites (Clithon oualaniensis), tiny snails each with a different intricate pattern on their shells.
Among the special snails seen alive and well today were: Several dolphin shell snails (Angaria delphinus), several Reef murex (Family Muricidae), one Black-lipped conch (Strombus urceus) and several living Pink moon snails. Although there were many empty shells of Pink moon snails. And I didn't see a single Gong-gong (Strombus canarium) today, either dead or alive.
Also missing were the Nerite snails (Family Neritidae) usually common on the rocks everywhere. Today they were seen only near the canal. But we didn't see any dead Nerites either. Perhaps they are hiding our somewhere, waiting out the bad situation?

Many of the oysters stuck to the rocks were dead, with their shells gaping open.
I didn't see a single live Fan shell (Pinna sp.) which usually lie half buried in the sand. But I also didn't see more dead clams than usual. And I did see several living Window-pane clams (Placuna sp.) which lie freely on the surface of the sand.
We saw ONE Common sea star (Archaster typicus). It did not seem to be disintegrating.
I'm kind of glad I didn't see any special 'never before seen' animals today. I realise that usually means these animals are stressed.

There are many different types of seagrasses on this shore! There is a small patch of Tape seagrass (Enhalus acoroides) . I learnt from Len of Seagrass-Watch that this seagrass grows in a 'circle'. It's quite obvious in this small patch. As Andy remarked, the seagrasses today were quite 'clean' of the usual scummy epiphytes that settle on the seagrass blades.
There was also a patch of Sickle seagrass (Thalassia hemprichii)! The grass here also looked alright.
These structures are part of Eugene's and Siti's seagrass study. Alas, all the seagrasses they were studying have gone. I didn't come across a single patch of Spoon seagrass (Halophila ovalis). I do hope they might eventually re-emerge from their buried underground stems (called rhizomes).
The patch of Ribbon seagrass (Cymodocea rotundata) on this shore has grown much bigger! There are now two patches, each covering about 2m square. So far, I've only seen this seagrass at Chek Jawa and Cyrene Reef. The blades are green and clean and lots of tiny Dubious nerites are settled on them.
In between the two lovely patches of Ribbon seagrass was a bag of soft stuff. It had absorbed oil and was leaking it back onto the shore! What to do about this? Brainwave! Travis has some small plastic bags and uses them to protect his hands as he drags the bag all the way to the high shore. Andy films the progress. Bravo!
When I first arrived, I saw piles of huge bags. Probably containing oil stained sand. It's good to know they are bothering to clean this shore.
It seems they had used those absorbent rolls on this shore. That's good to know. In the distance, a pack of wild dogs roamed the shore. It seemed relatively clear of heavy oil, with only some light staining on the low water mark.
Still, on most of the water on the shore there is sheen of oil, and a thin layer of brownish scum.
There is a short stretch of seawall stained deeply black. I also wonder whether the geofabric (in the foreground) which is part of the seawall construction, will absorb oil and continue releasing it onto the shore?
On some rocks, the grazing animals like tiny snails and limpets seem to be already eating the scum growing on the surface. I don't know how this will affect them over time.
Alas, this shore remains affected by a never ending slick of rubbish. From abandoned fish traps to litter that floats in with every tide.
How will this shore be affected by the oil spill in the long term? I really don't know. We can only visit it regularly and keep track of changes. And hope for the best.

After the rain, there is a rainbow over the ships parked in this sea overlooking this shore.
As the rainbow sheen over the water on Tanah Merah disappears, so we hope for a full and complete recovery of this remarkable shore.

More photos of the Tanah Merah shores before the oil spill.

See also Marcus' post about this trip.

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