15 June 2014

Spongeless on Sekudu

It's always a delight to see the Estuarine seahorse. I almost missed it because it looked very much like the sea fan that it was holding on to.
We made two trips to check up on Pulau Sekudu. Sadly, like our survey of Chek Jawa yesterday, we noticed a marked absence of sponges here.

Very much like Chek Jawa yesterday, most of the rubble at Pulau Sekudu looked like this. Just a sprinkling of sponges or none at all. Most of the rock was covered by a variety of seaweeds. It looks like seaweeds have replaced sponges on the rubble.
The most abundant sponge was this Yellow bumpy sponges. There were also many Chocolate sponge, and the rocks were mostly coated in Melted chocolate sponge.
There were also many less colourful sponges, and only very few clumps of the more colourful and previously common sponges.
Because sponges were concentrated mainly on large boulders, it was easier for me to spot the nudibranchs. Like this Hypselodoris which is commonly seen at Changi too.
Here's a pretty nudibranch I saw on a bunch of hydroids.
Here's another nudibranch on hydroids too.
And this little one that we call the Cow nudibranch.
Another first time find was this cowrie with a red body mantle. I'm still not sure what it is. I also saw a few Noble volutes.
Abundant on the lush seagrass meadows were Swimming anemones and White sea urchins. The sea urchins carry bits of seagrasses, seaweeds and debris, so it's important to look carefully while walking so as to avoid crushing any of them.
There were a lot of large living Fan clams on the shore. And when these die, the shell provide homes to crabs, fishes and in this case, a Miliaris cowrie.
This Reef octopus really blends well with the sand. I also saw a Slender seagrass octopus and a Pygmy squid. There were also some Geographic sea hares and Spotted sea hares.
There are lots of Swimming crabs of various kinds, and some were seen in mating position or getting ready to mate, like these two crabs. Also common here are Stone crabs. I also saw one Spearer mantis shrimp and many Orange-striped hermit crabs. As well as some Orange fiddler crabs and Porcelain fiddler crabs.
I also saw this strange creature.
I think it's the Transparent spoke anemone.
How nice to see a Haeckel's anemone. There were many Haddon's carpet anemones and none of them were bleaching. Posy anemones were also common on the rubbly areas all around the island.
Like Chek Jawa, there were many small patches of Zebra coral, and many (about 10) small to medium-sized colonies of Boulder pore corals.
I only saw a few sea fans. Several Candelabra sea fans, one small cluster of Tree seafan, and one Gnarled sea fan. I didn't see any Skinny sea fans.
There were a lot of Flowery sea pens, Spiky sea pens and I saw one Slender sea pen. I saw several ball flowery soft corals, but no other kind of soft corals. Button zoanthids were still abundant. Strangely, I came across very few Cerianthids.
I haven't seen this sea cucumber before! It was hidden under a rock and moves rather rapidly. Its front end has a different pattern and is narrower, while the hidden rear end is more bulbous and plain. While there were many Garlic bread sea cucumbers, I only saw a few Orange sea cucumbers and one Pink warty sea cucumber.
The pair of Diadema sea urchins with ferocious long spines are still there! I saw one Thorny sea urchin.
I saw one Common sea star! These sea stars are no longer common on Chek Jawa since they were wiped out in the 2007 mass death. Marcus found a patch of many Common sea stars. The most abundant sea star were Biscuit stars. There were also some Sand stars. The rest of the team also saw some Knobbly sea stars. I also found Cake sand dollars, while the team found one Pink sand dollar. Chay Hoon found a huge Oval heart urchin.
I also saw three Blue feather stars over the two trips.
The island provides shelter to many different kinds of fishes: Blue-spotted fantail rayFilefishes, and some wrasses as well as some fishes that I can't identify.
There are many kinds of fan worms here! Although there are some ascidians, none of us found any flatworms.
The patch Serrated ribbon seagrass that I saw on in 2011. was still there! It was about 5m x 5m.
I saw two Tape seagrass clumps. Their leave blades are very long (more than 1m) and one of the clumps had female flowers.
I also saw some dugong feeding trails in the lush seagrass meadows there. The most abundant species are Spoon seagrasses . There are also lots of healthy looking Fern seagrass.
It was good to see the Perepat trees were free from the caterpillar infestation that ate up all the leaves on these trees in Aug 2013.
I also spotted this cute little gecko on the tree! How did it get onto the island?
On the first trip, we ended the trip before sunrise.
As seen from the GIS map done and shared by Dr Raju, there is a kind of arm east of the island which is only exposed at the very lowest tides. I did the western side of the island on the first day, and the eastern arm on the second day. As on our trip in Jul 2013, the entire lagoon and the outer 'arm' is still very sandy. With large areas of bare sand and signs of immobile animals such as corals being buried. Where is the sand coming from?
On the first day, the team found a 50m monofilament net which looks freshly laid (no encrustations). It had a mesh size of about 10cm and there was only one Stone crab trapped in it. On the second day, the team also found fish traps. They released the fishes and destroyed the traps.
Alas, I saw remains of a TV on the high shore. This obviously didn't float to the island and was probably dumped there. It is heartbreaking to see these kinds of impacts on Pulau Sekudu.
As we left on the second day, we saw burning taking place on the large platform abandoned on Chek Jawa.
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 Pulau Sekudu. Our last survey was in Jul 2013. Thanks to Alan at NParks for permission to visit and to Chay Hoon for organising the trip! And for the rest of the volunteers for helping to thoroughly survey this small but very rich island.

More about why I think it's important to regularly survey Pulau Sekudu and Chek Jawa.

Posts by others on this trip

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