Pulau Semakau: conservation and urban needs

Thanks to Huang Danwei for the alert to this article "Conserving reefs beside a marine landfill in Singapore" by Prof Chou and Karenne Tun about environmental planning that balances urban needs with conservation of our shores.

"Pulau Semakau, commissioned as a landfill in 1999, now has its extensive reef flat supporting an average live coral cover of 30% and 24 coral genera, with good diversity of other reef invertebrates and large beds of seagrass.

Natural coral recovery also occurred at abandoned rocks not used for construction. Tours are conducted for the public and access is restricted as part of the continuing protection measures.

These are the results of effective environmental planning. The development previously destroyed the reef on the east of Semakau, but steps were taken to protect the western reef, such as building of membrane-lined rock bund that encloses the landfill, and positioning of silt screens to prevent sediment damage during the construction of the perimeter bund."

Chou, L.M. & K.P.P. Tun (2007). Conserving reefs beside a marine landfill in Singapore. Coral Reefs 26: 719-719.

The article is available on SpringerLink (subscription required)


Links to more
Pulau Semakau intertidal walks conducted by the volunteers of the Raffles Museum of Biodiversity Research.
About Pulau Semakau on wildsingapore

Frog Island revisited

A late evening tide and we were off to have a look at Pulau Sekudu or Frog Island. As always, we are anxious to see signs of recovery. Like Chek Jawa, Pulau Sekudu was also affected by the flooding early this year, but not as badly.

We are delighted to see blobs, gobs and other colourful stuff growing back on the big boulders. By the way, these are all animals! We're excited because nudibranchs eat these encrusting animals. And we love nudibranchs.

Alas, we didn't see many nudibranchs. I saw this pair of fugly nudis, which are possibly Thordisa villosa.And Chay Hoon (of course) found a miniscule nudi. Tiong Chin broke his back photographing it, thus sparing me the agony of having to do so. Ron also took a good photo. We shall just slackly await one of them to blog the photo.

It was encouraging, though to come across this large egg mass laid in a spiral on the boulder. It certainly looks like a nudibranch egg mass. Ron also came across a spiral among the seagrasses. So we can hopefully look forward to seeing more nudis later on.

On the rock was also this ... ahem, Rock star (Asterina coronata).This was my big star for the trip. But the others found the 8-armed sea star (Luidia maculata) and Ron saw the Cake sea star (Anthenea aspera). Wow!

Hopefully, soon we will also see the Knobbly sea stars (Protoreaster nodosus) that used to crowd this shore. Alas, we didn't see any tonight.

It was also encouraging to chance upon this young Sandfish sea cucumber (Holothuria scabra).These animals unfortunately died in large numbers on Chek Jawa during the Big Flood. It's good to see them coming back.

Just after I told Adelle that the season for sea urchins was probably over, I came across this little white sea urchin (Salmacis sp.?). By then, she and her party were too far away to call back.This rather camera-shy animal 'carries' objects and is thus hard to spot although it is bright white!

Tonight, we're off duty from the Nem Hunt. But we still documented them by photographs.

There were a few Haddon's carpet anemones (Stichodactyla haddoni).And some really tiny sea anemones. I'm not sure if this one is a baby Haddon's carpet anemone or Stichodactyla tapetum.

There were several swimming anemones too.And the sand was just teeming with the tiny anemones that we've already seen at Sembawang, East Coast and Changi. Wow! It's just stunning what we can see if we look closely.Albert and friends saw a moving sea anemone! But a look at the photo suggests it was probably an anemone stuck to a shell occupied by a hermit crab.

The shores of Sekudu were also teeming with fishes. Tiny TINY ones swarmed in schools among the seagrasses.

This large toadfish (Family Batrachoididae) lurked on the bottom pretending to be a stone.While this young rabbitfish (Family Siganidae) is perfectly camouflaged among the seaweeds.On the water surface was an odd little halfbeak with a shovel-shaped lower jaw that is many times longer than it upper jaw.Seagrasses are an important nursery for fishes, many of which are important food fishes. Pulau Sekudu and Chek Jawa are probably important areas where our favourite seafood can breed and grow up before moving out to our other nearby shores. Keeping these two areas as no-fishing zones will probably result in better fishing nearby.

Thus it is heartening to note that access to Chek Jawa and Pulau Sekudu by boat is now restricted. A permit is now required from NParks to land on Pulau Sekudu. See the NParks website for more details scroll to "Notice to Vessels"; "PDF of Designation" and "Application for Permit".

Andy also did a quick check on the trash situation on Pulau Sekudu, and it seems to have improved.

Well, this is the last of the low tide trips for a while. As usual, at this time of the year, there's a few weeks when there are no low tides. This is a time for us to catch up on sleep, give public talks, conduct training, plan for the next series of evening tides.

Links to more blogs about this trip
Ron's tidechaser blog: butterflyfish, more sea cucumbers, the lovely large Cake sea star, tiny nudibranch and more.
TC's mountain and sea blog: cuttlefish, black peacock anemone, 8-legged sea star and more.

Evening at St. John's

It's the first evening tide of the season as the morning super low tides ease off. And the usual bunch of beach stalwarts were out to revisit St. John's Island, beneath a threatening sky.Lying just off the Sisters Island, St. John's shore is crammed with all kinds of marine life.Soft and hard corals abound.

Some hard corals flouresce at dusk, the bright green polyps glowing in the water!Among the first things spotted, by Ron, was a Spider conch (Lambis lambis).Later on, I spotted the pretty snail on the right. I don't know what it is.

The usual egg crabs were seen; Red egg crab (Atergatis integerrimus) and Brown egg crab (Atergatis floridus).Both these crabs are highly poisonous to eat. So they are rather 'bo-chap' and trundle about slowly on the shore.

As it got dark, the octopuses started coming out.Worms also got busy. While most people may consider them icky, the worms on the shores can be quite fascinating.I saw a black flatworm with an orange-and-white edge to its frilly body (on the left). As well as a very VERY long ribbon worm (on the right) in its striped pajamas.
Some worms have bristley sides (left), others have feathery tentacles on their heads (right).

There was a LOT of sargassum of various shapes on the shores. And the brown seaweed was literally crawling with dove snails.They seemed to be grazing the algae off the broad brown blades of the sargassum. You can see the 'clean' areas next to these snails.
Of course, once there's a whole bunch of animals all grouped together, hanky panky seems to be part of the festivities.

The shore was also full of fishes.The little darting cardinals easily distract from well camouflaged fishes like this Painted scorpionfish (Parascorpaena picta).

Other assorted fishes were encountered.I don't know what the fish is on the left; while on the right is the tail of a Carpet eel-blenny (Congrogadus subducens) which obviously burrowed into a crevice that was too short for it.

Marcus yelled "Stingray all around me!" and I rushed over, carefully, to have a look.There were several small Blue-spotted fantail rays (Taeniura lymma) flitting about with the incoming tide. We managed to snap this one that stopped for a little while.

Nem Mode never really being switched off, even though the nem team was not with us, I looked out for nems.There were lots of frilly anemones (Phymanthus sp.) of various patterns and colours.And this transparent thing that looks like a sea anemone, but is actually probably a peacock anemone as it has a ring of smaller tentacles in the centre, and I've seen these live in tubes.As the tide came in, I thought I should have a look at the swimming lagoon.

On the way there, I bumped into a Land hermit crab (Coenobita cavipes). These pretty animals are more active at night. They are very happy on the shores, scavenging for food and keeping things clean and tidy. It's a pity that some people take them home to keep as pets. Our marine life should live wild and free instead of caged for the pleasure of a few people. The Land hermit crab is unfortunately listed among the threatened animals of Singapore due to habit loss and over-collection.

In the swimming lagoon, the sand was littered with creeper snails.I startled a Ghost crab (Ocypode ceratophthalma) and came across a juvenile Gong-gong (Strombus canarium) which had not yet grown the extended 'wing' on the shell. And right in the middle of the lagoon, were clusters of Common sea stars (Archaster typicus)!These sea stars are no longer common and are in fact listed among our threatened animals. It was thus a delight to see them there. Many were stacked in pairs getting ready to mate. There were also some smaller ones, which is rather unusual to see.

St. John's is truly a marvellous shore that's very much alive.

There are lots of other sightings that I missed: seahorse, velcro crab and more. Here's more about the trip on other blogs:
Chay Hoon's colourful clouds blog: seahorse, more fishes, flatworm and tiny nudi and a successful waterproof camera test.
Ron's tidechaser blog: weird anemones, velcro crab, moon snails and more about how spider conch snails gather together.
The budak blog for a more lyrical account of our trip, and a feature on the land hermit crabs found there, perhaps two species on St. John's?
July's discovery blog: our very own native pong pong tree, rocky features, anemone shrimp and more.
Kok Sheng's wonderful creations blog: reefs crowded with life, great billed heron, lots of crabs and more.

Despite the ominous clouds and threat of rain as we began the trip, the evening turned out to be clear with a velvet sky sprinkled with stars. The water was equally clear, even with the incoming tide!

Andy and I noted that the rubbish we saw tucked into the cliffside on our earlier trip had been removed to the high shore. That's good.

On a less happy note, poor July's camera went swimming today. Sigh. That's one of the hazards of exploring our shores.