14 January 2013

Dugong signs on Changi with sea fan garden

Dugong feeding trails on mainland Changi! These characteristic furrows show that dugongs have been feeding on the seagrasses here recently.
Another daylight trip to the lush seagrass meadows with glimpses of underwater gardens of sea fans, sponges and more!

The tide was lower than we expected, but still not low enough to clearly see the sea fans (Order Gorgonacea) that grow on the rockier parts of this shore. Sea fans can grow in murky water because they don't have symbiotic algae that rely on photosynthesis. We had a much better look at the sea fans during a good low tide in Jul 2012.
Here's a closer look at some of the sea fans.
Sea fans are a great place for other animals to live. These include these Winged oysters (Family Pteriidae) which are only found on sea fans. Also, a strange white thread-like thing wound around this sea fan. I have no idea what it is. Kok Sheng found a strange clam on a sea fan too. I didn't see any ovulid snails though.
The rocks are also coated with colourful sponges of all kinds, including Zebra corals (Oulastrea crispata) and Cave corals (Tubastrea sp.). The sponge variety at Changi seems quite different from those we saw at Punggol the day before. So every shore in Singapore is precious!
There's also lots of life among the sponges. This cluster of branching purple sponges is a handy spot for mama squids to lay their white sausage-like egg capsules.
Other pretty creatures on the shore include several Biscuit sea stars (Goniodiscaster scaber), some large Haddon's carpet anemones (Stichodactyla haddoni), many Swimming anemones (Boloceroides mcmurrichi), several Thorny sea cucumbers (Colochirus quadrangularis), Warty pink sea cucumbers (Cercodemas anceps) and buried Ball sea cucumbers (Phyllophorus sp.). The rest of the team also found two frogfishes and an octopus!
It was nice to see the Luidia sea star (Luidia sp.) which I don't often encounter. It is a burrowing sea star and has pointy tube feet on the underside. Like other Luidia sea stars, it has pretty star-shaped structures on the upperside.
Pei Yan showed me this pair of Hairy sea hares (Bursatella leachi) which are easy to overlook for seaweeds.
On the rocks, I saw white coils that look like eggs laid by the nearby limpets.
A small part of the shore was covered with colourful Button zoanthids (Zoanthus sp.). Our last trip here was in Jul 2012 and the shore seems to be doing ok.
There were lots and lots of people out on the shore. Some were sightseers, many were systematically foraging on the shore with buckets and bags. Chay Hoon and Pei Yan persuaded a young boy to release a seahorse he had found.
Many fishermen were cast netting in deeper water. I had a look at some of the gear used by the fishermen and the marine life they caught. There was a good variety of fishes, crabs and prawns.
On the richest part of the rocky shore, I came across a man preparing to cast net in the area. He got off the rock and stomped into the water to cast.
As usual, there is litter on the shore. What is perplexing is to find many very large bags (my foot in the photo for scale) mostly for rice, also ice. There were also many other large bags without any markings. Where did these come from?
But what can most seriously affect this shore is 'beach improvement'. This is when sand is dumped on the top of the beach to make it look nicer. Eventually, the sand of course washes down and buries the seagrasses and can seriously set back the habitats. I noticed this happening on this shore in Dec 2008. I suspect 'beach improvement' has also happened on another Changi shore in Aug 2012.

Posts by others on this trip
  • Kok Sheng with lots of sea fans, octopus, frogfish! 
  • Pei Yan with giant octopus and close ups of all kinds of animals including a fireworm.


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