21 March 2012

Thousands of dead fishes at Sungei Api Api?

Media articles reported that thousands of small 5cm long dead fishes "were found at the mouth of Sungei Api Api and along Pasir Ris beach" on 20 Mar.
Today I had a look at the area to look for signs of mass deaths. Would it be like the situation we saw in Dec 2009 where the beach was littered with hundreds of dead fishes of all kinds?

Sungei Api Api seems clear of dead fishes, both the muddy banks a little further up the mouth of the river (photo above), and at the sandy banks near the mouth (below). There was a whiff of dead fish though, at the bridge. It smelt more like being at a salted fish factory than nauseating.
I had a quick look at the beach to the west of the mouth of Sungei Api Api. As usual, there's lots of styrofoam litter on the high shore.
On the high water mark, there were a few sparse scatterings of small dead fishes.
The low water mark during this neap tide (about 0.6m Tg Changi) was covered in a thick layer of Sea lettuce green seaweed (Ulva sp.). I didn't find any dead fishes of any kind among the seaweeds.
But there were signs of other life. Like this nice moult of a Mangrove horseshoe crab (Carcinoscorpius rotundicauda).
I also saw many moults of Flower crabs (Portunus pelagicus). I checked for transparent eyes, to confirm that they are moults and not dead crabs.
There were even a few patches of fresh green Spoon seagrasses (Halophila ovalis). These seagrasses are quite lush lower down where it's more often submerged.
There were a few hermit crabs (Clibanarius sp.) out and about despite the rain, the rocky shores had Drills (Family Muricidae) busy laying eggs, I saw a couple of moon snail sand collars and some burrowing sea anemones.
I then headed for the beach on the eastern side of the mouth of Sungei Api Api. There I also saw  sparse scatterings of these small dead fishes on the high water mark. There were no dead fishes on the low water mark.
I walked the beach all the way to Sungei Tampines, and at the mouth of Sungei Tampines, I saw these few different kinds of dead fishes. I didn't see any other dead fishes of any kind.
On the muddy banks of Sungei Api Api, there were lots and lots of Egrets. Lined up along the water's edge as well as clustering under the mangrove trees.
I went into the eastern muddy banks of Sungei Api Api for a closer look. There's the usual assortment of washed up litter.
Here, the fishy smell is a lot stronger and there were scatterings of these small fishes. I didn't do the western muddy bank because the rain got heavier and lightning got closer.
During my walk, I saw obvious signs of erosion on many parts of the beach.
Erosion is also seriously affecting the mangrove trees growing near Sungei Tampines.
As usual, there is a great deal of litter on this beach, even though it is regularly cleaned.
A cursory look at the kind of litter and it seems to be that they come from the fish farms opposite the shore (large plastic bags previously containing rice, washing powder) as well as users of Pasir Ris beach (small packets of snacks, drinking straws, toiletries).
I also came across a tangle of abandoned fishing line. It took no trouble at all for me to remove it. Sad that the person who abandoned it didn't make this small simple effort.
I was very surprised to see three elaborate set ups of fishing nets and traps in the mangroves on the western side of the mouth of Sungei Tampines.
Here's a closer look at the trap above.
Further in this very tiny patch of mangroves, a more extensive square set up of fishing nets.
The net doesn't seem to be regularly checked by the person/people who put it up, as this fish caught in the net was not removed.
A mangrove tree branch is bent to nearly breaking point to anchor this strange trap.
Another elaborate trap set up with coconut leaves arranged around a fish net.
The fish traps are not very far from the granite breakers in this very small patch of mangroves that is already suffering from erosion.
Despite the rain, fishermen were setting up on the bridge over Sungei Api Api.
I wondered what goes on upstream of Sungei Api Api? Sungei Api Api is special because the mangroves lining the stream were part of a conscious decision by NParks to re-establish the original mangrove habitat there after reclamation at Pasir Ris and works to deepen the Sungei. The experience in this experiment was not only applied to Sungei Tampines which lies nearby, but also to mangrove restoration at Pulau Semakau!

Further upstream, however, the Sungei is canalised. Here, I saw a large construction site for the Belysa Executive Condos.
Here's a map of the area. The portion I surveyed today is in light blue.
In February 2011, Grant Pereira shared about several incidents of pollution that killed off marine life at Sungei Api Api.

In media reports, PUB said "(The fishes) were likely to have been washed in by the tide, and some of them were deposited on the river bed of Sungei Api Api. The contractors are currently clearing the dead fishes". The foreman of the crew who have been cleaning Sungei Api Api for two years told the press that he thought the dead fish came from Serangoon Harbour, near Pulau Ubin

"PUB assures the public that this incident has no impact on drinking water quality. The water in Sungei Api Api is not used for the drinking water supply." The National Environment Agency is also investigating the cause of the incident.

Update 22 Mar: A new media report says "NEA has ruled out water contamination as the cause of their deaths. It said yesterday that it analysed water samples from the area and did not detect any irregularities. There was also no discharge of toxic chemicals or pollutants into Sungei Api Api on Tuesday." Also "Fish farmers there have not reported any fish dying in their farms. Algae blooms which kill fish have also not been reported in the area recently."


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