28 April 2013

Sharky Terumbu Semakau

Another predawn arrival on a submerged reef in high water! Knee-high water is perfect for sharks and rays which hunt smaller fish in the shallow water.
So we are careful as we land in the clear waters of Terumbu Semakau.

Kok Sheng spotted a huge sting ray zooming out as we headed for the reef. Later on, I saw a shark chasing leaping fishes but it was too far to photograph in the dark. Chay Hoon later saw a cute baby Bamboo shark and took a great video clip of it!


There were lots of other fishes too, like this intriguing Burrowing snake eel (Pisodonophis crancrivorous). This fish is not a true eel and distinguished from true eels by its rather comical tiny circular fins near the head.
During a night reef walk, we can usually see lots of octopuses. Though they are often not very easy to spot. Can you find the octopus in this photo?
Here's one that's much easier to spot as it gracefully 'flew' across the sand with its eight arms.
Reefs are rich because animals live on animals! But you have to look closely to find some of them. This rather boring looking clump of branching Acropora corals (Acropora sp.) are home to several tiny blue-eyed coral crabs (Cymo andreossyi), as well as lots of tiny coral clams (Pedum spondyloideum)! These animals are superbly camouflaged in their coral home.
Even a rather smooth boulder Pore coral (Porites sp.) can have many tiny animals. On the right photo among the tiny flower-like polyps of the coral are tiny brown patches which are acoel flatworms, and banded feathery filaments of possibly a coral barnacle that has burrowed into the coral. Most of the corals on the reef seemed alright and I didn't see any signs of coral bleaching on this trip.
Today, both Kok Sheng and I found the scary Alicia sea anemone (Alicia sp.). It looks rather innocent when the tentacles are retracted, just another boring thing on the reef.
This is what the sea anemones look like when their tentacles are expanded. I have yet to see one with the tentacles fully expanded in the wild.
Here's another strange sea anemone I spotted tucked among some rocks. I'm not sure what it is. Perhaps the unidentified Neon sea anemone? Or a small Bubble tip anemone (Entacmea quadricolor).
There were also several Magnificent anemone (Heteractis magnifica). I saw one with a pair of anemone shrimps (Periclimenes brevicarpalis). The female is larger with larger white spots, while the slender male is more transparent. The tide was still high so the 'Nemo's or False clown anemonefish (Amphiprion ocellaris) were well hidden under the sea anemones. Their presence marked by sudden and rapid wiggles among the tentacles.
We all saw a lot of Glossodoris atromarginata today. I didn't see any other nudibranchs, but Kok Sheng found a special one.
I saw this strange whelk (Family Nassaridae) that I've not seen before. I'm not too sure what it might be. Kok Sheng also found a Fluted giant clam (Tridacna squamosa)!
The large patch of Montipora corals (Montipora sp.) I saw on my last trip here in Nov 2011 are still there.
Alas, there still isn't much seagrass on the reef.
Here's what the seagrass meadows looked like when we visited in June 2010. The seagrass meadows  became sparse when we visited in March 2011 and they have not recovered since then.
There were some Tape seagrass (Enhalus acoroides) that were long, especially among the rubbly and reefy area. But those in the sandy areas were shorter or curled up. Most were heavily covered in epiphytes.
This is what the better patches of seagrasses looked like. Small bladed Spoon seagrass (Halophila ovalis), with a sprinkling of long Serrated ribbon seagrass (Cymodocea serrulata) or Sickle seagrass (Thalassia hemprichii). I sense the situation is about the same as when I last visited this submerged reef in Nov 2012.
In the dark, lots of emissions are going on at the petrochemical plants on Pulau Bukom.
After sunrise, the huge plumes of emission are more obvious.
This is one of the boat strikes on the reef that we have seen before. It takes a long time for such 'scars' to heal.
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 Sep 2012.

Click on image for larger view.
Here's larger view of  Terumbu Semakau and other islands and reefs nearby. We enjoyed good clear weather until it was time to leave. Then it started to rain heavily. Just because we're on a dinghy doesn't mean we can't use an umbrella!
It's tricky landing in the dark and departing rapidly in bad weather. Which is why we are doing these recces to prepare for the Mega Marine Survey's  upcoming Southern Expedition in May. It also helps to have experienced people like Alex and Jumari to take us to the right spot!

Tomorrow, one more early morning recce trip and then straight into the first day of the Bryozoan and Hydroid Workshop! It's going to be a very long week for me.

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