Bug hunting in Singapore Polytechnic (SP) (19 Nov 2008)

This time, I turned my attention to my very own campus to find out just how well established are the bug populations in our ponds.

The first pond is a relatively long one (~ 20m) well stocked with Koi and other large fishes. It stretches along the boundary of the campus along Commonwealth Avenue West. This is a really cool idea as it acts as a fence without installing a fence. With Esther's help, we combed through the bed at a few spots for bugs with the now familiar net. Besides lots of floating green algae, the whole place is a desert devoid of bugs. Oh, did I mention that the bed is made of an artificial stone? This, plus few aquatic plants and the presence of swarms of hungry fishes probably account for the bug free environment.

We next checked out the pond at the Eco-garden. "Eco-garden" sounds like an nice place to find a balance ecology. This is a smaller pond with nice landscaped waterfalls. Apparently, the name can be deceptive. With feet stamping on the bed of big rocks and net vigorously sweeping through the water, nothing turned up. (Is this a surprise or what?) The only "bug" we found was a snail shell (sans the snail) attached to an underwater rock.

Overall, SP has been a disappointment in its bug population. I guess that is what comes from making everything artificial.

Water Quality Monitoring in Bukit Timah Area: Ngee Ann Stream (18 Sep 2008)

We headed to this nice natural looking stream (affectionately termed "Ngee Ann Stream" due to its proximity to Ngee Ann Polytechnic) right after checking out Binjai Stream (see post below). But do not be mistaken about its naturalness... this stream will soon flow through a concrete tunnel before ending up in Ulu Pandan Canal.

At the first sampling point, we managed to net a big (~ 3cm length) damselfly nymph hidden in a bunch of waterside grasses and it is ALIVE! (We found a discarded exoskeleton earlier.) Regrettably, my camera is not good at capturing small objects so the pic is not posted here. However, other than the clearly irritated damselfly, no other macroinvert was netted though there were lots of hydrilla crowding one another out.

We tried our luck at bagging some macroinvertebrates at the second sampling point. No luck! We only found some gastropods (snails) firmly attached to underwater rocks. The other bug of interest is a cute looking, whitish Collembola (Springtail) inching its way across a rock surface.

It appears that our waters in Singapore are not exactly teeming with macroinverts. Do we have a problem here?

Figures (L - R): The scenic and natural open country freshwater stream that is Ngee Ann Stream; searching for bugs at the second sampling point; the naturalness giving way to stone and concrete; a surprising find - belukar (secondary forest) hidden next to the stream

Water Quality Monitoring in Bukit Timah Area: Binjai Stream (18 Sep 2008)

I had the honour of being attached to the Marine Biology Lab in NUS for a week. During this period, I learned more about the use of macroinvertebrates in water quality monitoring. The attachment was made more interesting with a field trip to one of my favourite haunts for recreation and water quality monitoring.

Binjai Stream is located in the Binjai area of Bukit Timah. Casual trekkers are not likely to stumber upon the entrance to this stream as it involves wading through a long, dark tunnel under an expressway. The occasional inhabitants of the tunnels, swifts of some kind, fiercely demonstrated their displeasure at our intrusion by playing touch-and-go near our faces.

This can qualify as one of the cleanest streams we have monitored. Forests surround the stream and the clear waters are occupied by numerous pond skaters. Unfortunately, the area further upstream is subject to land slides, especially after heavy rains. This really messes up the water quality as the stream water quickly becomes "kopi susu" with high levels of suspended sediments.

Yet despite the clear and clean (indicated by water quality tests) water, the benthic macroinvertebrate population was surprisingly disappointing. Kick sampling with a net yielded little macroinverts. Most were surface insects such as pond skaters.

Is this a normal trend in our waters? Or could this imply something unpleasant festering in the background? We do not have the answer at this point.

Figures (L - R): A freshwater crab deftly scoped up; numerous pond skaters; Esther working on the net to score some macroinverts; typical habitat of Binjai Stream