05 July 2015

Sunrise survey of Pulau Sekudu

We landed well before dawn for our annual survey of Pulau Sekudu, a tiny island just off Chek Jawa on Pulau Ubin.
Although the seagrasses are doing well, the sponges are still missing and the situation does not seem to have improved very much from last year.

Like at Chek Jawa yesterday, most of the rubble at Pulau Sekudu look like this. Just a sprinkling of sponges or none at all. Most of the rock was covered by a variety of seaweeds.
The sponge situation is similar to what we saw at Chek Jawa yesterday. The diversity of sponges and number of sponges on the shore remains low and seems to be deteriorating. Today, the situation was worse than in Jun 2014 which was worse than in Aug 2013. The most common sponge was Melted chocolate sponge, the dark rose pink sponge that I have yet to figure out, and Yellow bumpy sponges. There were clusters of Yellow horn sponge, some Golf ball sponges, Spiky ball sponges in various colours, many Chocolate sponge, as well as clumps of black sponges. I didn't see any Purple branching sponge.
The most abundant anemone were Posy anemones, the most abundant sponge were Yellow bumpy sponges. There were also a few clumps of Button zoanthids.
A tiny Reef octopus that appears to be clutching something in its arms at its burrow. There were lots of Swimming crabs of various kinds. I also saw a Red egg crab and a Maroon stone crab.
I saw three large Knobbly sea stars in deeper water. The rest of the team also saw more Knobblies. The most abundant sea star on the shore were Biscuit sea stars.
I saw one feather star in deeper water, the rest of the team found more. I missed them but Marcus saw the Diadema sea urchins that usually encounter here.
I saw two of these corals which I think is Tiny ring coral, a kind of Favid coral. I saw many small patches of Zebra coral, but I didn't come across the Boulder pore corals that I saw in Jun 2014, but Kok Sheng saw some.
I came across one Miliaris cowrie and several Onyx cowries. As well as the usual cowries. There were also some Noble volutes on the seagrass meadows. The rest of the team found many different kinds of nudibranchs and Kok Sheng found a lot of flatworms.
There were a few sea fans, all large and well formed without any commensals.
I saw one Flat branch sea fan and two Skinny sea fans. Kok Sheng and the rest of the team saw more.
As we had already noticed in Jun 2014, the lagoon is still sandy and mostly bare although there are sprinkles of seagrasses and many Haddon's carpet anemones here and there. Where is the sand coming from?
The Serrated ribbon seagrass patch is still there, growing among lush Spoon seagrasses. The area here has become super soft. I didn't see it, but the rest of the team found Tape seagrass with leaf blades that were rather long (about 30-40cm) but appear cropped at the ends.
There were lush growths of Fern seagrasses, and abundant Haddon's carpet anemones. I did not see any anemones that were bleaching. Today, there were also a lot of large Swimming anemones among the seagrasses and some White sea urchins. I only saw a few Flowery sea pens.
I noticed a lot of Fan clams sticking out of the ground. Many of those sticking out that I checked were dead. Perhaps the live ones can dig down into the ground? Even dead, the empty shells provide shelter for small animals and a place for encrusting creatures to grow.
The Perepat trees are still full of leaves. Caterpillars had eaten all their leaves in Aug 2013 but they recovered in Jun 2014.
The rest of the team found all kinds of interesting things including TWO Hollow-cheeked stonefishes. Kok Sheng shares more underwater photos too.

Pulau Sekudu means Frog Island and there is indeed a huge rock in the shape of a frog on the island. Someone had helpfully added eyes and a smile on the rock. There is a legend about an elephant, a pig and a frog and how they formed Pulau Sekudu and Pulau Ubin. More here.
Large container ships pass through the Johor Strait to or from Pasir Gudang in Johor.
Just off the island are large fish floating fish farms.
Also passing by every morning are large barges piled with sand being brought to Singapore's sand stockpile on the mainland near Tampines.
There were fish traps all over Pulau Sekudu. Altogether, the team took care of 8 functioning traps, most of them had live or dead fishes. In one trap, I released one Emperor, one filefish and two Eel-tail catfishes. In another, I released a large Copperband filefish.
There were fish traps at the reef edge. And I could see plastic bottles in the water marking traps in deeper water. Today, we did not see any newly laid fishing nets, but there were many old abandoned nets that were already heavily covered in seaweeds. It's a pity more is not being done to manage the fishing impact on Pulau Sekudu and Chek Jawa.
That's me and Dr Chua Ee Kiam as we reminisce and chat at the end of our trip. Dr Chua is writing another book about Pulau Ubin! Salute! I can't wait to read it!
This little island lies just off Chek Jawa on Pulau Ubin. It is part of the Chek Jawa Wetlands that is managed by NParks.
Pulau Sekudu is off limits since 2007 and requires special permission from NParks. Thanks to NParks for permission and support to do these predawn low spring tide surveys of Chek Jawa. Thanks also to Chay Hoon for making all the transport arrangements. And the team for helping to cover as much ground as we can during the narrow low tide window. Thank you!

Chek Jawa and Pulau Sekudu may be affected by the 2030 landuse plan by the Ministry of National Development. The plan includes plans for a road link (black line) from the mainland jumping off at Punggol, crossing to Pulau Ubin through Chek Jawa to jump off to Pulau Tekong before circling back to the mainland on Changi East. Proposed reclamation (in yellow) will bury Pasir Ris shores, Pulau Sekudu and Chek Jawa as well as a large amount of shore at Changi Beach.
Click on images for larger view.
I feel it is thus important to update our understanding of what is going on in the field at these sites including Chek Jawa and Pulau Sekudu.

We probably won't be back to visit Chek Jawa and Pulau Sekudu until next year. I hope these unique and beautiful shores remain well until then.

Posts by others on this trip

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