26 July 2010

Checking up another Changi shore

Today we check up a rather neglected stretch of Changi. I got a distinct whiff of crude here (a smell I encounter on Tanah Merah). But I couldn't find the source of the smell. It was particularly strong near the rocky areas.
Nevertheless, the shore was still lively. Here's one of the three young Cake sea stars that I saw today.

Here's the other two Cake sea stars (Anthenea aspera). They still had long arms and all were about the same colour and pattern. As they get bigger, their arms get shorter. From what I've encountered so far, it seem only the older ones have different colourful patterns.
But it was rather quiet in terms of echinoderm sightings today. I only saw one Sand star (Astropecten sp.) and did not see any Biscuit sea stars (Goniodiscaster scaber).
I saw two Thorny sea cucumbers (Colochirus quadrangularis), one Pink warty sea cucumber (Cercodemas anceps), many ball sea cucumbers (Phyllophorus sp.) buried in the soft silty sand, and one Orange sea cucumber. I didn't see any sea urchins.
I came across several large brittle stars (possibly Ophiothrix longipedia), their arms sticking out of hiding places in the rockier area. But I didn't see any of the brittle stars that sometimes roam the seagrasses at night.
Today, the soft silty shore was teeming with small carpet anemones (5-8cm). Many of them were tucked into their body columns, a situation that I seldom encounter. Some were bright green and one was bright purple. Some of these might be young Haddon's carpet anemones (Stichodactyla haddoni).
But many of the carpet anemones appear to be the Tiny carpet anemone (Stichodactyla tapetum).
There were lots of Peachia anemones (Peachia sp.) and several swimming anemones (Boloceroides mcmurrichi). But I didn't see any Tiger anemones or other anemones such as the Glass anemone (Dofleinia sp.). These are usually quite common here.
I saw one very tiny Flowery sea pen (Family Vertillidae) and an even tinier Slender sea pen (Virgularia sp.).
Various kinds of peacock anemones (Order Ceriantharia) are still on the shore: small banded ones, larger Dusky peacock anemones and many Common peacock anemones. I am beginning to realise that the black Phoronid worms are only seen with Common peacock anemones.
What a strange and beautiful creature! It was small, about 5cm long. I have no idea what it is. A kind of sea pen?
The rocks near the work site are coated in the usual variety of encrusting animals. From oysters to limpets to barnacles.
There were lots of little blobs on the rocks. Dr Daphne has taught us a lot about these blobs, and a closer look suggests they might be different kinds. The ones with the fine lines are the Lined bead anemone (Diadumene lineata). While I'm not sure what the one with dots along the body are. The lower two are probably the larger Banded bead anemones (Anthopleura sp.).
Under the stones, Stephen found a black hoof-shield limpet (Scutus sp.).
Also under a stone: What is this? A kind of ascidian?
A strange looking worm-like creature with scales and hairs are squirming among the keelworms under the stone.
There were still cowries on the rocky areas. These are probably the Ovum cowrie (Cypraea ovum).
Some clams I saw included the pretty patterned Venus clam (Family Veneridae), and a very young Fan clam (Family Pinnidae).
There were a lot of these blue swimming crabs (Thalamita sp.) just hanging onto the rocks. And schools of these little fat fishes.
Striped hermit crabs (Clibanarius sp.) and Tidal hermit crabs (Diogenes sp.) patrolled the shore.
The Spoon seagrasses (Halophila ovalis) looked alright today, with bright green leaf blades covering large parts of the very soft and silty shore. Although the seagrasses seems less lush than before, I didn't come across any bleaching seagrasses.
The shallow pools were full of tiny fishes. There were also a lot of tiny snapping shrimps (Family Alpheidae) on the shore.
A tiny Coastal horseshoe crab (Tachypleus gigas)! But I didn't come across the seahorses we saw on our trip earlier this year.
There were a few large purple branching sponges (Callyspongia sp.) and lots of melted chocolate sponges (Chondrilla australiensis) and a few small colonies of the hardy Zebra coral (Oulastrea crispata). Some zoanthids still covered the higher shores. But I couldn't find any signs of sea fans today.
It's the first time I'm back here since Feb 10. Many of the animals seen today were juveniles, suggesting the shore is recovering from some impact.

We had to cut the trip short as it started to storm!

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.
Let's hope this shore continues to recover and is spared further impacts.

Fortunately, there are other stretches of Changi that are still rich, such as the one we visited about a week ago.

Tomorrow, another stretch of Changi that we seldom visit.

4 comments:

  1. UPL Unity was involved in seawall works off Pulau Ubin... likely parked at the sheltered area off Changi when not required. http://www.mpa.gov.sg/sites/circulars_and_notices/pdfs/port_marine_notices/pn10-73.pdf

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  2. Thanks Anonymous for this information!

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  3. Ria, when you can smell the "crude" but not see it, this implies that the light factions of the crude has "dissolved" into the surrounding porous structures!

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  4. Oh dear. Thanks for that information anonymous.

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