Sunday, February 2, 2014

Oil spill check at Northern Semakau

There was a collision on 29 Jan evening between a chemical tanker and a containership which happened "about 2.7 km, south of Jurong Island". This has caused a spillage of bunker fuel in the surrounding waters. On a Lunar New Year holiday, we decided to swing by the Semakau and Terumbu Raya area to have a look at the impact of this oil spill.

We had a large team and thus could afford to split into two, one that landed on Terumbu Raya and I was part of the Pulau Semakau team. We landed at northern Semakau which is the part that is closest to Pulau Hantu and Jurong Island.

Thankfully, there isn't much of visible oil patches or slick on the shores on Semakau as like the ones we saw on Kusu the day before.

However, there is still a layer of oil slick that can be found at different part of the high shore.

While Andy walked all the way south to document the impact, I walked further north and northeast to cover more ground. Here's a photo of the thin layer of oil near the mangroves.

At some parts, the oil is more visible but they are pretty much localised and not all over the shore.

Today is also my first time walking from the northern tip to the eastern shore of Semakau which is closer to the 7km rock bund of the Semakau landfill. This stretch is sure soft and there were many moments of falling into the soft mud. There were also many branching sponges and cyanobacteria that cover huge expanse of the shore.

Here's a closer look at the branching sponges that sticks out like fingers. :P

I came across a Furry sea hare (Stylocheilus sp.) and touched it like what I did at Kusu yesterday. I was relieved to not feel any oil on its surface.

A pleasant surprise would be to find yet another juvenile Fluted giant clam (Tridacna squamosa)! It was sitting on top of a boulder hard coral.

The giant clam shell looks quite clean without much "commensals" living with it. I did not find more living giant clams though.

Instead, I stumbled upon this patch of many, I really mean many dead adult giant clam shells.

These are mainly shells of the Fluted giant clams. I think it could be a result of people dumping these dead shells on the shore after.... eating them? Hmm...

The eastern shores of Semakau is home to lots of the Magnificent sea anemones (Heteractis magnifica)!

It is amazing to find them even at the most "lifeless" rocky high shore near the replanted mangroves. There were not much evidence of oil impacting this part of the shore.

That's not all, these magnificent sea anemones can even be found in great numbers at the reef edge!

The reef edge facing Terumbu Semakau is very pristine with lots of hard corals and other reef associates exposed at low spring tide. The water was pretty clear as well!

Here's another view of the reefy area with Terumbu Semakau and Semakau Landfill at the background.

This photo shows a variety of animals such as hard corals of different species, a Long spined black sea urchin (Diadema sp.), a huge Barrel sponge (Xestospongia testudinaria), and also the Magnificent sea anemone on the right.

There was a good assortment and variety of uncommon and not-so-common hard corals that can be found on Eastern Semakau.

I even saw a huge colony of the Physogyra Coral (Physogyra sp.)! 

Correction: Thanks to Jeff Low for the correction, this coral is actually Plerogyra sp. instead of Physogyra sp. These two coral genus look similar but Physogyra is a solid, boulder form, compared to the wavey meandroid form of Plerogyra sp. (which is shown in the photo).

Plerogyra corals have bubble-like vesicles and trumpet-like corallites with separate walls. I'm quite excited as this is my first time seeing this coral on our intertidal shores.

Today was my first time observing predatory snails feeding on the Galaxy corals (Galaxea sp.). It's amazing how these snails can feed on the retracted tentacles of the coral.

The Reef octopus is a king of camouflage! They can and will change colour and shape to blend into the environment.

At the reefs, I saw many different types of sea anemones ranging from this unknown anemone with neon stripes on its body column. The tentacles look like that of the Bulb-tentacled anemone (Entacmea quadricolor).

This Pizza anemone (Cryptodendrum adhaesivum) was found wedged amongst the rocks at the reef edge.

As the tide was low, many of the commensal clownfish such as this pair of Tomato anemonefish (Amphiprion frenatus) were stranded or trapped in the tide pool.

Just right beside the exposed Giant carpet anemone (Stichodactyla gigantea) are some other stranded
False clown anemonefish (Amphiprion ocellaris).

Though I tried to push it to a pool of water, I guess this is all part and parcel of living in between tides where stress is inevitable.

This bluish anemone which can sting badly when touched is actually known as the Fire anemone (Actinodendron sp.). The oral disk has white stripes with small dark spots, radiating from the mouth. 

Before we depart, I had a quick look at what lies near the northern yellow beacon at Semakau.

The shore was mostly covered with sargassum seaweed and there were only a few spots where the marine life was not obscured. There are some stretches with hard corals and sponges.

This Stonefish sea cucumber (Actinopyga lecanora) is quite commonly seen on the reefs of Semakau. Thankfully we did not see (or step on) the real stonefish today.

Shall end my post with this shot of the beacon legs with the lights of Bukom at the background. Quite like this view of the sea at dusk.

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