16 November 2012

Tiger on Terumbu Semakau

My first time finding a Tiger cowrie (Cypraea tigris)! This special snail had been seen before by the team on this reef, so it's thanks to them that I knew where to look.
I'm on Terumbu Semakau, a submerged reef just off the Semakau Landfill, to check up on the disappearing seagrasses on the reef as well as to look at the health of the marine life in general in the face of ongoing coastal works nearby.

Here's what the magnificent creature looks like. The snail is listed as Endangered in Singapore.
It's timely to visit Terumbu Semakau because of the nearby ongoing work by Shell to replace the SBM pipeline which would involved dredging and other major works. I attended a Shell briefing on this in September.
Click on image for larger view.
Here's a map of Terumbu Semakau.
Another of my goals this trip is to check up on the seagrass situation on Terumbu Semakau. Alas, the lush seagrass meadows that I saw in the past are gone. There were only small patches of seagrasses, mostly covered in epiphytes and badly 'chomped' Tape seagrass (Enhalus acoroides).
Here's what the seagrass meadows looked like when we visited in June 2010.
This was the 'densest' patch of seagrasses I came across.
This is what the seagrasses looked like in May 2012. The situation looks even more dire now. This situation has been going on for more than a year. The seagrass meadows were already sparse when we visited in March 2011. Let's hope the seagrasses recover soon.
I also took the opportunity to check for coral bleaching. It was a little disturbing to see some white Cauliflower corals (Pocillopora sp.). But the polyps are still brown and when submerged, the white skeleton is not so obvious. There were a few colonies with yellowing or pale portions but I didn't see any colonies that were fully bleaching.
I came across a wide variety of corals and most of them seemed in good health.
Some of the Asparagus soft corals (Family Nephtheidae) were rather yellow, while others were the more normal purple. I saw a few large leathery soft corals (Family Alcyoniidae) and none were bleaching.
It was nice to see a large colony of Acropora corals (Acropora sp.).
I was surprised to see a large patch of branching Montipora corals (Montipora sp.)! The patch was about 10m square.
In checking up on the seagrasses, I didn't spend much time on the reef edge. Which was densely covered in thick seasonal bloom of Sargassum seaweed (Sargassum sp.). But the rest spent much time here and Kok Sheng found special corals, sea anemones and another Fluted giant clam (Tridacna squamosa)!
Kok Sheng also found a pretty Alicia sea anemone (Alicia sp.) which we rarely encounter. It has a really nasty sting so we handle it very carefully. Here's some studio shots of this wondrous creature.
I also saw lots of other sea anemones today. Many Giant sea anemones (Stichodactyla gigantea), one of them with a big 'Nemo' or False clown anemonefish (Amphiprion ocellaris) hiding in it. Also two Fire anemone (Actinodendron sp.), and many beautiful Magnificent anemone (Heteractis magnifica). As well as one Haekel's anemone (Actinostephanus haekeli)!
There was also an Upside-down jellyfish (Cassiopea sp.), which is rather common on Pulau Semakau. Jim is going to have a closer look at it to see if it glows in the dark.
Although called the Common sea star (Archaster typicus), this animal is no longer as common as it used to be. This is my first time seeing it on Terumbu Semakau. This sea star is still among the most widely distributed of sea stars in Singapore.
Oh dear, this deep gouge on the reef looks like a boat strike. When a boat runs aground on the reef at high tide. During our trip here in June, we saw a boat strike on the opposite side of this reef.
We were blessed with dry cool weather! And a muted but pretty sunset. It was also a relief to see no new fish traps or abandoned driftnets on the reef.
Back on the boat, Jim shows us how some sea creatures glow in the dark! He is working on taking photos of flourescence in sea creatures. An awesome glimpse into yet another aspect of our marine life!
Later today, we'll be back on the shore to check things out at St. John's Island.


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