03 February 2010

Seahorse search at sunset

I enjoyed a lovely sunset with Collin and friends from NParks as we searched for seahorses at Changi.
This shore was recently affected by construction to remove a jetty and redo the seawalls. So I wasn't sure if there would be anything there, much less seahorses!

So it was a nice surprise to see the seagrasses doing very well, with small and large leaves of Spoon seagrasses (Halophila ovalis) covering nearly the entire shore all the way to the mid-water mark. The most abundant animal there were Common peacock anemones (Order Ceriantharia). In various colours, true to their common name.
There were also a few of these smaller peacock anemones with slender banded tentacles.
Also seen dotting the shores in regular intervals were Thorny sea cucumbers (Colochirus quadrangularis). Most were small or tiny, hardly bigger than a seagrass leaf. This little sea cucumber was lying on top of a small carpet anemone (Stichodactyla sp.) which I totally missed until I processed the photo.
I came across one larger Haddon's carpet anemone (Stichodactyla haddoni).
And also one small Glass anemone (Doflenia sp.). But alas, I didn't see any of the other larger anemones that we used to see on this shore.
There was one Flowery sea pen (Family Veretillidae) with its polyps retracted.
While on the rocky area affected by the construction work, there were lots and lots of Button zoanthids (Zoanthus sp.), the polyps forming greyish blue cushions here and there. There wasn't much else on this shore. And though I tried to peer through the murky water, I couldn't see any sea fans either.
The work site area was rather barren, although the rock face was carpeted with a thick layer of seaweeds and small animals such as oysters and barnacles had already settled there. Some the oysters have already been vandalised. Hopefully by natural predators and not by humans.
On the other rocky area far away from the work site, there were the usual common encrusting marine life. Like this Zebra hard coral (Oulastrea crispata), a really tough bunch of polyps that seem to thrive on our northern shores.
There were also a few clumps of colourful sponges. But I failed to find any slugs or flatworms.
In the seagrass area, there were lots of crabs: (clockwise from left) the well camouflaged elbow crab (Family Parthenopidae), and hidden Leaf porter crab (Family Dorripidae), buried Moon crabs (Family Matutidae) and lots of little swimming crabs (Family Portunidae).
I saw one of these very pretty Reticulated moon crabs (Matuta planipes) which so far I've only seen on another part of Changi.
There were also many small prawns (Family Penaeidae) that would grow up to be the kind that we eat. Seagrasses are indeed important nurseries for our favourite seafood.
Other youngsters in the seagrass were many young Gong-gong snails (Strombus canarium) which have yet to develop a thick lip on their shells. The upperside of the shell is well encrusted with camouflaging stuff.
There were also lots of tiny fishes, as well as somewhat bigger ones. Like this half hidden eeltail catfish (Family Plotosidae).
And a well camouflaged flathead (Family Platycephalidae) which was quite small.
Of course, the star attractions of a northern shore! I saw several tiny baby sea stars among the seagrasses.
Here's a slightly bigger one, which looks like it might grow up to be a Biscuit sea star (Goniodiscaster scaber).
I also saw some small Plain sea stars (Astropecten sp.).
And one medium-sized Painted sea star (Astropecten sp.).
My weird encounter of the day: a short segment of bristleworm that seemed to still be twisting around in the sand.
A closer look and it turned out to be a large Olive whelk (Nassarius olivaceus) eating a bit of worm. The whelk's shell was encrusted with long strands of seaweeds.
And the team DID find a seahorse (Hippocampus kuda)! Jeremy found it! Hurrah! After Collin tagged it, it was released. So I didn't get a photo of it.

If you see a seahorse at our northern shore, please gently take a photo of both sides of the animal (make sure it is in the water). If you have a flickr account, please share it on this flickr group Seahorse sightings in Singapore (and have a look at the many seahorses seen!).

With more sightings we can have a better understanding of where our seahorses are found and how to better protect them.

This particular stretch of Changi is regularly 'beat' up by various activities.
Bumboats plying the Changi-Ubin route zoom past the area. It is regularly fished by prawn harvesters, cast-netters and line fishermen. Since late 2009, there has been a barge with excavators working this stretch of shore. There was no MPA notice about this work, so I'm not sure what they were supposed to do. From observations, it seems they took down an old jetty and redid the seawalls there. It was only in the last few weeks that the works had ended.Dredging of Changi Creek seems to happen every one to two years. This also affects the shores nearby.
Despite these pressures, our Changi shores are still very much alive. With special animals such as sea horses. On some visits, the shore is very soft and silty. On yesterday's trip, the shore was quite firm with only small areas of soft silt. This results in different kinds of plants and animals found on this shore at different times. Another reason to keep an eye on this shore.

1 comment:

  1. Thanks for the name of that matuta spp crab. I have been looking for this id.

    i got a whole list of marine creatures to id & i need your help.

    ReplyDelete

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