09 May 2012

Giant clams at Terumbu Semakau

A glorious sunrise explodes despite the dark clouds as we land on Terumbu Semakau to rescue more giant clams for Mei Lin's project.
We found clams! Also snake, 'Nemos' and lots of healthy corals on this submerged reef right next to Semakau Landfill!

We approach Terumbu Semakau as the sun rose under dark clouds. This submerged reef is just beyond Pulau Jong (the little 'char siew pau' shaped island on the horizon), and very close to the Semakau Landfill (the Transfer Station is to the right). The city on the skyline is less than half an hour away!

On the other side of this amazing submerged reef are the refineries on Pulau Bukom!
Terumbu Semakau is very close to the original Pulau Semakau which has mangroves, reefs and seagrass meadows. Rain brings rainbows! I joked that our Giant clam is probably at the end of that rainbow. And it turned out, that is about where we found it!
Here's a map of Terumbu Semakau.

I'm delighted to see that the corals on the edge facing Pulau Semakau are nice and healthy. I only saw one slightly bleaching hard coral.
This is what I saw during the mass coral bleaching event in June 2010.
Coral bleaching on Terumbu Semakau
It's nice to see so many healthy corals crowded next to one another on this reef edge.
And they are all very colourful and not bleaching.
Here's more glimpses of the crowded corals on this shore.
I also saw a cluster of several Tongue mushrooom corals (Herpolitha sp.).
There are many species of hard corals on this shore, including many well grown specimens of some of the less commonly seen corals. I didn't really focus on hard corals today because the job was to find giant clams!
The only bleaching animals I saw were several Asparagus soft coral (Family Nephtheidae) that were rather pale. On the right is the usual purplish colour, on the left, not so good. I didn't see any bleaching Leathery soft corals. I'm rather nervous as we approach the summer season. Kareen tells me there are already reports of coral bleaching in the Philippines. More about coral bleaching on Bleach Watch Singapore.
We love going on our adventures with Alex of Summit Marine. He really looks out for us, literally. The crew made a surprise stop in the middle of our trip, to bring Kareen an umbrella. They must have noticed that she didn't have one and it had been drizzling for some time! We are so touched by their concern.
So now, Kareen is nice and dry as we survey this amazing shore!
Aha, a Fluted giant clam (Tridacna squamosa)! But it was tiny! About 10cm long. Much too small to be involved in breeding. So we leave it behind to grow up.
Finally, I saw a large Giant clam! See how close it is to the Semakau Landfill! The white wavy lips give it away at low tide. During high tide, its fleshy 'lips' inflate so that the clam can feed off sunshine. Like many hard corals, Giant clams harbour symbiotic algae (xoozanthellae) which undergo photosynthesis and shares the food produced with the animal.
Kareen takes a photo of the clam with the scissors for scale. She uses the scissors to gently and carefully cut the byssus threads which the clam secretes to stick onto a hard surface. This doesn't harm the clam at all if done by properly.
Kareen says this Giant clam is a mother. Giant clams start out as males and only become female when they are larger. She estimates this one is about 12 years old! It takes a long time for a Giant clam to grow up. We are so glad the Summit Marine crew dropped by again to help us carefully carry this big mother clam back to the boat. She is heavy!
As we hunt for clams we find other interesting marine life. Kareen found a Banded filesnake (Acrocordus granulatus)! It was just resting among the rubble. These snakes are associated with mangroves, and there is a huge stretch of mangroves on Pulau Semakau!
There are lots and lots of Magnificent anemone (Heteractis magnifica) on Terumbu Semakau. These large sea anemones come in a wide range of  colours. The body column may be pale pink, shocking pink, orange or yellowish. Tentacles may be purplish, bluish or green. Truly magnificent!
'Nemo's or Clown anemonefishes (Amphiprion ocellaris) live in these large anemones. At low tide, however, sometimes the poor fish is stranded when the anemone is out of water! I gently put this mama clownfish into a pool of water and she was quite fine. The tide was turning in about a half an hour and I'm sure she will be happily reunited with her anemone then.
I also saw a few Bubble tip anemones (Entacmea quadricolor). This one didn't have bubble shaped tips, which sometimes happens.
A heart urchin! I seldom see this burrowing creature above ground. It is possibly Maretia ovata. But we can't be sure until the specialist takes a closer look at the specimen.
How delightful to see a Phyllidia varicosa nudibranch which I seldom encounter. It has a dotted black line on its grey foot! Unlike many nudibranchs which have a flowery gill on the back, these nudibranchs have gills on the side of the body. Besides the two tiny yellow rhinophores on top (which looks like one of the bumps), the nudibranch also has tiny tentacles near the mouth on the underside!
Oh dear, it seems a lot of the Tape seagrass (Enhalus acoroides) is still cropped short, compared to our last trip here in Dec 2011. I could see lots of short blades sticking straight up.
I did see some long Tape seagrass, also much Spoon seagrass (Halophila ovalis) although most was heavily covered in epiphytes. I also came across some patches of Serrated ribbon seagrass (Cymodocea serrulata). I didn't come across any Noodle seagrass (Syringodium isoetifolium) which we have seen here in the past.
Alas, I came across several large fish traps laid directly on the reef. But we didn't have time to remove them.
Before we left, I noticed emissions emerging from the refineries on Pulau Bukom.
Although today we didn't see any Indo-pacific dolphins (Sousa chinensis), Alex told us they saw about 6 playing in the water near St. John's Island last week!

The rescued clam will join some other wild clams from our shores as part of Mei Lin's effort to breed them and hopefully repopulate our reefs with these magnificent animals. Find out more about this project in Jose Hong's article in the Straits Times and on Mei Lin's blog.

More trips ahead as the low spring tides continue. But every day, the low tide is a little later. Tomorrow, I get to sleep, wake up call at a luxuriously late 5am!

No comments:

Post a Comment


Related Posts with Thumbnails