27 June 2013

Natural reefs on artificial seawalls with OTTERS!

Today, a few of us are exploring the amazing reef that has settled naturally on the artificial seawalls at Tanah Merah Ferry Terminal.
I saw lots of amazing corals, and also visited the seagrass meadows nearby. And otters were sighted!

An amazing variety of hard corals have settled on the seawall at the Terminal.
The reef grows right in front of the pontoons where huge ferries berth. It can only be seen at very low tides which seldom happen during daylight.
The corals have settled on a kind of 'platform' of rocks built out of the seawall, I think it's called a berm.
The corals grow well submerged and are only revealed at the lowest tides. Here's a view of the seawall, the colour change shows the waterline for the mid-level tide.
It's rather tricky surveying the slippery rocks. I started under the bridge and very slowly inched out.
Corals of different shapes are found here.
The corals were quite densely packed in some parts of the wall.
Various kinds of corals growing near one another.
There were even a few small colonies of Acropora coral (Acropora sp.) colonies.
As usual, Favid corals (Family Faviidae) are abundant with many colourful colonies, some of them quite large.
I saw a tiny colony of Anchor coral (Family Euphyllidae), several colonies of Anemone corals (Goniopora sp.) and Galaxy corals (Galaxea sp.).
I saw a small colony of Cauliflower coral (Pocillopora sp.), several of Boulder sandpaper coral (Psammocora sp.) and many medium sized colonies of Lettuce corals (Pavona sp.), and smaller colonies of Carnation corals (Pectinia sp.) which I couldn't take good photos of.
I saw many tiny Circular mushroom corals (Fungia sp.) still stuck onto rocks, and many small colonies of Brain corals (Family Mussidae).
Most of the corals that stick out above the low tide were boulder shaped. But submerged even at the lowest tides were many large and beautiful delicate plate-like corals.
Here's a look at some of the plate-like corals that I saw: Disk corals (Turbinaria sp.) of various kinds and many large colonies of Bracket mushroom coral (Podabacia sp.).
I'm not really sure what kind of plate coral this is.
Here's two huge plate-corals growing submerged on the 'platform' from the seawall.
A special coral that I rarely see: the Cabbage coral (Trachyphyllia geoffroyi). Sadly, it seems to be bleaching.
There were a few colonies that were pale or bleaching. But most of the reef seemed alright.
Here's a slideshow of MORE photos of this amazing reef on an artificial seawall! It was hard to take good photos of the beautiful reefs during this hazy day with only a tiny swimming camera. Though I think I did a better job today than when I first tried it in Jun 2012.

I also saw some reef animals: several the Spurred turban snail (Astralium calcar) which I don't see very often, and one Dolphin shell snail (Angaria delphinus). There was also one Sally-light-foot crab (Grapsus albolineatus) and a Red egg crab (Atergatis integerrimus).
This coral colony has tiny blue coral barnacles (Pyrgoma sp.) boring into it.
As usual, there is litter on the seawall, but not a lot.
Soon, the tide turned and I had to slowly crawl back up the very slippery seawall. As a ferry left the terminal, it belched black smoke and generated waves that washed up on the reef. This stretch of shore was hit by the massive oil spill of May 2010 and global coral bleaching in the same year. It was good to see that most of the corals seemed healthy. With a good variety of species. While I can survey the other intertidal parts of Tanah Merah regularly, this reefy seawall can only be safely surveyed once a year.
Kok Sheng the Human Climbing Crab first introduced us to this reef and surveys it every year to make sure it is well. He shares awesome photos of this reef on his blog: 2011 and 2010 and 2009. He has found yet another stretch of reefy seawall further away from the terminal. He surveyed it separately this year and shared awesome photos of what he saw there. Pei Yan and Rene visited this stretch today.

I hopped over to the other side of the seawall, where there is a sandy lagoon. Two large patches of seagrasses (orange arrows) have sprouted here.
The patches of Smooth ribbon seagrasses (Cymodocea rotundata) are now lush meadows that have grown enormously.
The seagrasses are dotted with Haddon's carpet anemones (Stichodactyla haddoni).
Isabelle and her NParks colleagues are here to do a survey for horseshoe crabs. They've just finished and were having a closer look at the rest of the shore.
In the short time I was on this shore I spotted a lively flower crab (Portunus pelagicus), a washed up squid (Family Loliginidae) and a large sea anemone, probably the Pearly sea anemone (Paracondylactis sinensis). I also saw a Garlic bread sea cucumber (Holothuria scabra) and Rene spotted a Frilly sea anemone (Phymanthus sp.).
Stranded at the low tide was a Brown stripe wrasse (Halichoeres bicolor).
And a Bartail flathead (Platycephalus indicus).
Rene found an Arabian cowrie (Cypraea arabica). This cowrie is usually found in reefs and we have seen it several times at Tanah Merah.
There doesn't seem to be much litter washed up on the shore today.
On the high shore, we gathered some seeds of mangroves and coastal plants that have washed ashore. So it is entirely possible for mangroves to eventually regenerate on this shore too. In fact, on my last trip here in May 2013, I saw what looks like a Mangrove Cannon-ball tree (Xylocarpus granatum) growing on the high shore!
We'll be using these fruits and seeds to tell stories at the upcoming Festival of Biodiversity! Come visit us at Vivo City to learn more about the amazing shores that Singapore has!

But what about the OTTERS??!!

Ah yes. When I met up with the NParks team, they excitedly told me about the otters that they encountered while doing their transect. Kwan Siong showed me these awesome photos of the otters!
Photo by Koh Kwan Siong on facebook.
Then when Pei Yan and Rene came back from their explorations of the seawall, they ALSO saw the otters! Wah, I totally missed seeing them even though I was between both groups. I comfort myself by saying that the otters probably didn't want to get too close to the ferries. And also by looking at the awesome videoclip of the otters that Pei Yan shared:

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