Tuesday, June 15, 2010

Checkup on Tanah Merah coral garden

The hearts of many nature lovers broke when Tanah Merah got badly hit by the recent oil spill. To make matters worse, coral bleaching is also going on during this period of time.

Will our coral garden at Tanah Merah survive the double impact? Will we lose what probably could be the best mainland coral site of Singapore? James and I decided to have a look ourselves this morning during a rare super low tide.

This is how the coral garden look like in July 2009. Most of the corals were not bleached and they were crowded over the intertidal area. Only about 5% of the corals were partially bleached due to natural mortality.

And as for today, June 2010, many of the boulder corals as seen from this photo seem to be rather bleached. Based on my personal rough estimation, about 30-40% of the corals I've seen today are partially bleached. In addition, James and I noticed that there is still a thin layer of crude oil on the surface.

Yet there are still some corals that have not been bleached. In fact most of the corals are not completely bleached, just like these coral in the photo.

Here are the boulder Favid hard corals (Family Faviidae) that were bleaching more than the rest.

In case you are scratching your head wondering what is coral bleaching? Bleaching happens when corals (and also other cnidarians) lose the symbiotic algae in their bodies which help produce nutrients. It is the algae that give the animals their colour. Scientists think that most bleaching is caused by an increase in sea surface temperature. Find out more about bleaching in the Bleach Watch Singapore blog.

Only some of the corals seem to be turning pink, which is actually a sign that it is diseased.

Here is a Brain coral (Family Mussidae) that seem to be losing its colour, which means losing its symbiotic algae (zooxanthallae).

Yet on the positive side, there are also many boulder faviid corals that are still doing fine.

Unlike that of Beting Bronok and other southern shores, the boulder Pore corals (Porites sp.) here at Tanah Merah seem to be more resilient towards bleaching. Other than a few of them, the rest of these corals seem to be still unbleached.

How about the mushroom corals? This Bracket mushroom hard coral unfortunately seems to be partially bleached.

Same for some of the Circular mushroom corals that we came across.

The most badly hit corals that are completely white in colour will be the branching Cauliflower coral (Pocillopora sp.) and the branching type of Pore corals (Porites sp.).

Will these bleached corals be able to recover? The answer is yes, if the stress is removed or lessened. I hope the conditions will return to normal soon. If it takes too long to do that, the corals will have a lesser chance of survival.

It was a great relief that many of the Acropora coral (Acropora sp.) are still not bleached. Corals not only contribute towards the reef and ecosystem, they are also home to creatures that live within it, such as this pair of lovely Broad-barred acropora gobies (Gobiodon histrio).

Furthermore, we also found some of the commensal porcelain crabs (Tetralia nigrolineata) that are usually found on the Acropora coral. They are very cute.

On the left is another type of crab that is quite well camouflaged, thus not very obvious in the photo. On the right side are a couple of clams that live among the polyps. James also found the Machine gun shrimp (Coralliocaris graminea)!

That's not all! I was excited to find a number of these juvenile Kite butterflyfish (Parachaetodon ocellatus) feeding on the Acropora coral polyps.

It's my first time seeing them with the coral. They are very cute!

Looking at the other coral types of the reef, the Lettuce coral (Pavona sp.) seem to be one of the toughest survival of the oil spill and bleaching event! Almost all colonies we came across were healthy! Yay!

At some sections of the shore, the plate corals can be quite extensive! Their size is much bigger than the already-very-big boulder corals.

Here are more plate-like corals that are still doing decently well!

Well it is certainty heartening to see that many hard corals are still fighting on to survive in the toughest environment! Nature is more resilient than we thought. I hope that they will eventually be alright.

How about the soft corals? There are very very few soft corals on this shore. I went to have a look at this finger-like soft coral that I saw last year. It seem to be doing ok, though I think it's only very slightly discoloured?

While these stumpy soft coral species are still ok! Yup, these are the only two colonies of soft corals I came across today.

While looking around, James and I also encountered some reef animals such as the Red-eyed reef crab (Eriphia ferox) on the left and the Red egg crab (Atergatis integerrimus) on the right.

I saw two of the Bulb-tentacled sea anemones (Entacmaea quadricolor) with Tomato anemonefish (Amphiprion frenatus). It was sad to see the anemones bleached. Hope the anemonefish can still survive and that the anemone will regain its symbiotic algae.

Tomato clownfish in bleached anemone from Loh Kok Sheng on Vimeo.

Here is a video I took of the anemonefish with the anemone.

Though it is a reality that bleaching is taking place and that the oil spill will have a certain level of impact on the reef, I guess we should also look at the brighter side that many of the corals are still hanging on. Let's hope that the coral garden will regain its former glory very soon!

More photos of the day's trip here: http://www.flickr.com/photos/koksheng/archives/date-posted/2010/06/15/


Unknown said...

May God bless these beautiful corals. Thanks for sharing the updates!


Think the Butterflyfish are the Eight-banded Butterflyfish instead.

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