11 September 2010

Oil-spill check on Tanah Merah, part 2

Yesterday, I checked another stretch of Tanah Merah that was hit by the oil spill three months ago.
How delightful to see not one but two of these Spotted hermit crabs (Dardanus sp.) which are not very often seen, and usually only near reefy shores.

I saw six living Common sea stars (Archaster typicus)! The largest number I've seen on this stretch since the oil spill. But this is still a low number and the animals were widely dispersed from one another. Unlike the situation in the other stretch of Tanah Merah which I visited the day before.
The Haddon's carpet anemone (Stichodactyla haddoni) is still there though it seems to have moved closer to the seawall. And the resident anenome shrimp (Periclimenes brevicarpalis) is still at home.
I saw the Plain sea anemone which seemed alright. We haven't figured out its identity yet.
The most abundant fish I saw were Ornate lagoon-gobies (Istigobius ornatus)! They swarmed on the bottom in large numbers!
There were many schools of very tiny fishes!
A Striated heron was hunting on the shore, probably attracted by these little fishes.
I did glimpse other fishes darting among the rocks. It's hard to spot fishes in the daytime. The only large fishes I saw were dead. There were three freshly dead Cresent perch (Terapon jarbua). Perhaps they were discarded by fishermen on the shore?
This large dead fish was wedged among the rocks. A cluster of scavenging snails have settled on its chin. I'm not sure what it is, or why it is bright red. Could it be the Hollow-cheeked stonefish (Synanceia horrida) which is quite common on this shore. I tried to pry it out but it was too firmly wedged and smelled terrible.
Most of the corals on the shore seemed normal with no signs of bleaching.
Most the large and small Favid corals (Family Faviidae) seem alright.
I inadvertently saw a cluster of small Circular mushroom corals (Family Fungiidae)! (i.e., I spotted them in the photo after I got home). There are also some Pore corals (Porites sp.) and all were their normal brown colour.
A few of the Favid corals were rather brightly coloured and flourescent. I'm not sure whether this means that they are stressed.
There were five clusters of zoanthids (Zoanthus sp.) that seem to be alright, three of them are quite large clusters, on rocks.
The rocks that appear dark, I notice are dotted with many little Bazillion snails (Batillaria zonalis) (which are still VERY abundant on the shore). Perhaps the snails are eating whatever is growing on the rock? I suppose that's a good sign?
There were piles of little shells occupied by tiny hermit crabs on these dark rocks. In fact, there were many of these hermit crabs busy on many parts of the shore.
I saw one living Black lipped conch (Strombus urceus). And a Spurred turban snail (Astraea calcar) which I rarely see! I also saw several Spotted top snails (Trochus maculatus) and there were some living Large false limpets (Siphonaria atra) grazing the rocks. All the snail shells were coated in the beige muck that covers all the hard surfaces on this shore. I didn't see any Dolphin snails (Angaria delphinus).
I saw more than ten fanworms (Family Sabellidae). They seemed mostly alright, expanding their fan of tentacles in the usual way they do.
I could have a closer look a the tube that this fanworm constructs to live in. The tube seems to be coated in icky stuff. Poor thing.
This stretch of shore which does NOT have a layer of crude on the mid-water mark, is still full of signs of burrowing Sand bubbler crabs (Scopimera sp.). I didn't see many crabs, although swimming crabs (Family Portunidae) dashed off into hiding places as I approached. It's not as easy spotting these animals during the day as it is in the dark. Worryingly, I didn't see any signs of Acorn worms (Class Enteropneusta).
The most abundant seaweed I saw was Mermaids fan (Padina sp.) which covered many rocks and hard surfaces.
Other seaweeds seen include many bunches of Sargassum seaweed (Sargassum sp.) and a few clumps of Lettuce seaweed (Ulva sp.) as well as many clumps of Agar-agar red seaweed (Gracilaria sp.), Codium seaweed (Codium sp.).
The patches of Smooth ribbon seagrass (Cymodocea rotundata) seem large if not larger than before.
There is a long line of crude along the mid-water mark near the Ribbon seagrass patches and sheen accumulates among the seagrasses.
Despite the onslaught, the Ribbon seagrass seems mostly green, although many blades were brown. I didn't see any bleaching. The seagrass was teeming with Bazillion snails (Batillaria zonalis) and Dubious nerites (Clithon oualaniensis).
The small clump of Tape seagrass (Enhalus acoroides) is flowering! I hear that plants often furiously flower when they feel they are going to die. So this is not necessarily a good sign I think.
The larger patch of Tape seagrass on the high shore was green, although the tips were brownish, and it too was flowering.
The patch of Sickle seagrass (Thalassia hemprichii) seems to be about the same size. It is submerged as the tide is not very low.
The Sickle seagrass was mostly green although there were leaf blades with brown tips and pale bases.
An underwater shot of the Sickle seagrass.
I didn't see any Spoon seagrass (Halophila ovalis).

Unfortunately, there is still a great deal of crude on the shore. In some parts of the shore, on the mid-water mark, there is a thick layer of crude under a thin layer of sand which shows up when I gently scrape the surface, and even when I step on the sand, which feels rather slippery and jelly-like. I don't know why the sand is pock-marked with tiny little holes.
The crude lies just beneath the sand. A step reveals not only sparkly black crude, and a rainbow sheen, but also the smell of crude, which still hangs around in this area. It smells almost the same as the day I went when the spill first hit the shore.
The stretch of crude tainted mid-water mark is quite long.
The streams flowing from the high shore reveal the black stuff under the sand.
Sheen still forms on some parts of the lagoon.
Unlike the Tanah Merah stretch I visited the day before, there wasn't any of the brown scum, and the area of white and green scum on the ground is not very extensive. I had a quick look at it as the sun set on this first evening low tide of the year.
A closer look at the white and green scum.
There is crude under the sand near the areas with the white and green scum.
Sheen emerges when I step on the ground.
On some parts, the area of sheen that emerges is huge! That's my foot at the lower portion of the photo.
Besides the spill, the marine life and corals on the shore have to cope with litter.
Some of the litter appear to be industrial in origin, not something likely to be dumped by recreational users. This is disturbing.
There are still piles of large trash on the high shore, including huge ropes, an abandoned 'sampan' or small boat, and an abandoned driftnet. Since I was alone, I couldn't drag out any of the trash. Quite frustrating.When I arrived, there were many line fishermen on the shore. Some had set up (complete with beach umbrella) on the rock wall facing the reefier part of the shore. Later on, I noticed some had come down to fish on the long seawall along the sandy shore as well.
A pair of young men who sound like they are from mainland China were busy exploring the shore. One was barefoot and the other in slippers. Here they are trying to capture a colourful swimming crab (which I think is not edible).
Although there is still much life on this shore, there are many pressures on it too. Let's hope it can eventually recover.

More about the oil spill on this blog and on the Oil spill facebook page.

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