17 March 2013

Checking up on Kranji mangroves

There's a thin sliver of mangroves at Kranji behind heavy industrial sites. I wondered how it is doing since I last visited in Feb 2011.
So I headed out this sunny morning to the mangroves overlooking Johor Baru across the Johor Strait. Alas, there's still a lot of rubbish on this shore.

The patch of rare rare Beccari's seagrass (Halophila beccarii) is still there.
All kinds of mangrove seedlings seem to have settled in the patch.
The seagrasses were quite lush, although the patch was small.
I saw a few large living Mangrove horseshoe crab (Carcinoscorpius rotundicauda)and many tiny ones in shallow pools of water among the trees. The Nature Society (Singapore) runs a programme that regularly monitors the horseshoe crabs at Kranji. Usually, members of the public can volunteer too for this programme. NSS has also published about their work on horsehoe crabs at Kranji.
I had a quick look under stones and saw many worms including this brown and black striped ribbon worm (Nemertea) that I've not seen before.
There was huddle of many tiny Onch slugs (Family Onchidiidae) under this stone.
Of course, there were lots of porcelain crabs (Family Porcellanidae). While most scuttle madly away, some will flatten out and stay still in the hope that you overlook them.
I managed to take a photo of how a Mangrove whelk (Littoraria melanostoma) hunker down at low tide. They use a bit of slime to glue the lip of the shell to a hard surface, then retract into the shell and seal themselves up with the 'door' or operculum. This is why we should not pick snails off the rock or tree. You can't glue them back on and when the tide comes in they may get washed away or be eaten by predators that come in at high tide.
I was trying to find mangrove bryozoans in anticipation of the Workshop on Bryozoans and Hydroids next month. So I scrutinised all hard surfaces. For the first time, I noticed that there were all kind of seaweeds! But alas, nothing that I recognised as bryozoans.
I saw these Nerite snails (Family Neritidae) that don't look like those I usually see. Well, there are 19 recorded species of Nerites on our shores and I haven't been paying close attention to those found in mangroves.
How nice to see many tiny Spotty sea anemones which Dr Daphne first found at Sungei Buloh. There were also many other small common sea anemones like the Lined bead anemone (Diadumene lineata) and Bead anemones (Anthopleura sp.).
I also had a closer look at ferocious Mangrove murex (Chicoreus capucinus) firmly wrapped around barnacles. This snail is a Drill and does drill holes through the shells of prey like barnacles. It takes a long while for the Drill to pierce the shell, so you shouldn't disturb them.
On a tree trunk, I saw this gecko  with strange spikes at the base of its tail. Nick Baker's awesome EcologyAsia website has lots of info about lizards and geckos of all kinds. But I'm not too sure what this is. Wouldn't it be great if it was the Maritime gecko? I didn't even know we had such a gecko.
Also on the tree a cluster of very hairy caterpillars. Don't touch these! The hairs can be very irritating.
The mangroves didn't seem to have changed much since my last visit two years ago. The mangroves here are suffering seriously from erosion. Erosion is a major issue in all our other mangroves in the Johor Strait, from Lim Chu Kang, Sungei Buloh to Mandai.
The huge patch of dumped tiles is still there. The trees growing in the area seem stunted as their aerial roots can't grow up for air.
The fishing hut is still there.
There was a pair of kayaks there too, chained up to a mangrove tree. And I met three friendly fishermen getting ready to line fish at the incoming tide.
What is new is a huge jetty in the distance, probably built by one of the industrial tenants along this shore. There was large stretch of washed up logs too.
Behind the pretty patches of mangrove trees the high shores are still swamped with rubbish. I've done a separate post about the rubbish situation here.
Hopefully, there will eventually be a solution to the trash issue on this shore.

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