18 June 2010

Oil spill aftermath at Tanah Merah: signs of life?

Despite the obvious signs of crude still on the shore, there is still life here! The most startling sight was of this pair of shorebirds. I think they are the Malaysian sandplovers (Charadrius peronii) that we saw on our Death March to the Lost Coast.
I learnt from the Bird Ecology Study Group blog that "They feed in pairs on remote sandy beaches. They feed on worms and other invertebrates like small crustaceans." Oh dear, oil tainted food can't be good for these rare shorebirds.

Another delightful encounter was with a living Spotted hermit crab (Dardanus sp.)! So far, we've only seen this hermit crab near reefs and it's not all that common.
I also saw several living Striped hermit crabs (Clibanarius sp.) although they were very shy. And a few small Tidal hermit crabs (Diogenes sp.) as well, though not many.
On some parts of the sandy shores, there are signs of lots of busy, living sand bubbler crabs (Scopimera sp.)! This is a lot more than what we saw on our trip two weeks ago. Other crustaceans seen include some skittish Flower crabs (Portunus pelagicus) which is normal behaviour for them during daylight. I didn't see any shrimps though.
The scary find of the day was this stonefish by Chay Hoon! Can you see it?
How about now? The Hollow-cheek stonefish (Synanceia horrida) is quite common on this shore!
Another great find by Chay Hoon: a pair of tiny seahorses!

There were still lots of little gobies swimming actively about in the shallow waters: The super tough Shadow goby (Acentrogobius nebulosus) were abundant. As were the Ornate goby (Istigobius ornatus). And the Common frill-fin goby (Bathygobius fuscus).
Fishes are generally very shy during daylight. I saw glimpses of groupers, flashes of smaller fishes. This is quite normal behaviour. We should revisit this shore at night to have a better feel of how the fishes are doing.

The only echinoderms we saw today were dead. There was the test of a recently dead Oval maretia heart urchin (Maretia ovata). We saw several of these heart urchins above ground when we visited the day after the spill hit the shore. These animals are usually buried. Today we also saw a test of a dead sea urchin, and Sam spotted a dying sea cucumber. And we didn't see any living Common sea stars (Archaster typicus).
How are the hard corals doing? There are several large hard corals on this shore. These two look fine. Nice and brown.
As we have seen on trip two weeks ago, there is also coral bleaching on this shore. But only a few of of the hard corals here were bleaching. Most are Pore corals (Porites sp.) with some Favid corals (Family Faviidae). We estimate about 20% of those found on this shore were bleached completely or starting to bleach.
It was only that it was bleaching that I noticed this hard coral. It seems to be a kind of Mushroom coral (Family Fungiidae).
There are many living Favid corals (Family Faviidae) on this shore. With a few large colonies. Here's a selection of those I saw that seemed to be doing alright.
Here's more Favid corals.
These Pore hard corals (Porites sp.) also look fine.
There were a few clumps of living colonial anemones or zoanthids (Order Zoanthidea).
Sam also saw one Haddon's carpet anemone (Stichodactyla haddoni). But we didn't see any other cnidarians.

The dominant lifeform on this shore are the Zoned horn snails (Batillaria zonalis) and Dubious nerites (Clithon oualanensis). Countless numbers of these tiny creatures carpeted nearly every inch of the low water area of this vast shore.
I was glad to see living specimens of these special snails: The Dolphin snail (Angaria delphinus) and the Reef murex (Family Muricidae). I saw only a handful of Nerites (Family Neritidae), but there were several Large false limpets (Siphonaria atra) which seem to be alive and grazing the rocks. I didn't see any other living snails though.
There were still signs of many acorn worms. Today, we did not see any peanut worms which appeared in large numbers soon after the oil spill hit the shore.
The fanworms (Family Sabellidae) were still alive, but still rather shy. Most seem to prefer not to extend their feathery tentacles into the water.
I also saw a few living Thumbs up sea squirts (Polycarpa sp.) on the rocks. On the high sandy shores, I saw some living Large cockles (Family Cardiidae) that I often see on sandy areas near reefs.
Amazingly, this shore has patches of some seagrasses that are not common in Singapore. This is one of the three patches of patches of the rare Smooth ribbon seagrass (Cymodocea rotundata). So far, we have only seen this seagrass on Chek Jawa and Cyrene Reef. The ones on Tanah Merah do not seem to be doing well, with many leaf blades turning brown.
This is probably because big blobs of brown crude have settled on the shore just in front of the seagrass patch (yellow arrow indicates location of seagrass patch). Two weeks ago, I took photos of this patch while it was underwater, and it was not a pretty sight.
There are two other patches of Smooth ribbon seagrasses a little further down. These don't seem to be doing well either.
There is also a small patch of Sickle seagrass (Thalassia hemprichii) growing lower on the shore near the seawall. Most of it seems to be fresh and green.
But some parts of the Sickle seagrass patch are turning yellow and brown.
There is a small clump of Tape seagrass (Enhalus acoroides). It is growing rather high on the shore and didn't look very good. The leave blades were rather 'crispy' and the tips were brown, while the leaf bases were yellowish.
There's another tiny clump of Tape seagrass growing in deeper water, lower down on the shore! And it was flowering.
Among the drift gathered on the high water mark, there are still lots of fresh broken Noodle seagrass (Syringodium isoetifolium). So far, we've only seen this seagrass on our Southern shores. Is there a large meadow growing somewhere near Tanah Merah?
I didn't see much seaweeds today, both in quantity and variety. Mostly Sargassum seaweed (Sargassum sp.) and some Codium seaweed (Codium sp.) and Mermaid's fan seaweed (Padina sp.).
In general, I would say the situation is not much different from what we saw two weeks ago. This is, however, much less lively than the shore usually is before the oil spill. Here's posts about our previous trips to Tanah Merah, and some photos of marine life we have seen on this shore.

As we were leaving, we have a glimpse of the seawall facing the sea. There is a marvellous reef here! Alas, we could see bleaching going on at this reef.
Kok Sheng went to check up on this reef a few days ago. Here is a photo he took of the reef in July 2009. How is this reef doing? Find out on Kok Sheng's blog. We didn't go down to have a look as the tide was too high. And you have to be a Human Climbing Crab to survive a closer look at this reef!

On our recent trips to this shore after the oil spill, we have seen a rainbow.
I see it as a sign of hope. We shall just have to keep visiting it to see how it is doing.

See also Chay Hoon's post about this trip. Sam shared about what he saw on facebook.

Tomorrow, we will check up on the post-oil spill situation at Chek Jawa with TeamSeagrass.

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