Tuesday, November 30, 2010

Are our streams dying?

First, it was Ngee Ann Stream - formerly natural (or "naturalised") stream surrounded by beautiful secondary forests was cleared and replaced by a canalised version. (See former posts - 1, 2, 3)

Now, development or rather its effects have come to my favourite tributary leading to Sungei Ulu Pandan. On 2 visits to this tributary as part of my field trip for my course on Freshwater Quality and Biodiversity, it was badly polluted by an ugly layer of black oil floating on the surface. On the first trip, the only living macroinvertebrates (bugs) we could find were a couple of blood worms. The second trip proved to be much worse with ZERO bugs and this time, besides the black oily film, there was also a strong petrochemical smell, presumably from the oil. Most of the adjacent vegetation have also been stained by the oil. I am skeptical that the stream can survive the ordeal.

Where could this oil have come from? Further upstream was some road construction works and even further up, a golf course was being extensively cleared. Were they the culprits? Possible but no way to tell without further investigation.

There goes another educational site. It was already small to start with though we could still find dragonflies, damselflies, snails easily then. We even found the odd freshwater eel sometimes. Now, I will have to crack my head to look for another viable alternative.

I happened to see this recent article: Stormwater Runoff Disrupts Urban Stream Life. This study in Seattle basically says that stormwater carries many pollutants from the land into water bodies, killing or driving off aquatic life. Though nothing new, it reminds us of the interconnectivity between human activities and nature and especially the relationship between land use and water.

At first sight, land and water appear separated and independent but never forget that water in stream does not just come from upstream, it comes from a much wider land area known as the watershed. Anything bad going down in the watershed can eventually find its way into the stream and even the sea. I heard of this interesting remark that "we all live downstream", meaning our (or human) actions will often come back to haunt us, whether for good or bad depending on what the said actions were.
Figure: Black oily stuff floating down from upstream. Though the aquatic plants managed to block off the bulk of it, the oil inevitably trickled downstream to kill off the bugs in the stream.

Figure: Another view of the oil

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