Field Day at Sungei Buloh Wetland Reserve (SBWR) (28 Mar 09)

A perfect day for water quality monitoring - the morning weather is bright with a good tide coming in - no lack of water for monitoring and sampling.


Students are all fired up for half a day of field work though they seem more interested in the surroundings than in their tasks of water quality monitoring. This is understandable considering that most of them have not set foot on SBWR. Neither have they ever set their sights on the insects, fishes, plants of a mangrove swamp. In a way, it is lamentable that our youth does not have the inclination or time to visit such natural areas but it also presents a great opportunity for Nparks and schools to work harder on their environmental education programmes.


Amazingly, some students confessed that they prefered a wilder area for a field trip e.g. "Ngee Ann Stream" where you have to bash your way through tall grasses and hurt your butt through slipping on mud. SBWR? "Too civilised for us"


As the day wore on and the sun reached its zenith, weariness grew on their faces... one started to see the standard "too tired to talk, too tired to think" behaviour. Perhaps the route we took has passed the point of diminishing returns. This is something to review for the next run of this module.


But something unexpected showed up to bring them back to full attention - a full blown shower with accompanying thunder with us stuck at the last sampling station and the visitor centre clearly out of sight. I consider this the highlight of the trip as it reminds us to respect nature. Nature does not care for your plans and to-do lists, it just does what it does but offers an exciting environment very different from the controlled conditions in a lab or classroom.

Figures (L-R, T-B): Checking out the resident fauna at the main bridge; clambering among the trees to get a good spot at the water edge; "environmental couple" at work; grand finale - sprinting back to the visitor centre, then the bus in bone drenching rain.

A myth busted... and a new believer is born (10 Mar 09)

How often do you hold onto a belief for years and see it busted to shreds within minutes? Not often, I hope unless you have been living in a cave.

It started as another lesson for a secondary school. These students were brought out of the classroom to yet another field trip to a nearby pond. They were given big, robust nets and told to dig into the bottom mud and be aggressive about it. No big deal for kids 50 years ago but for them, it was a novelty... a thrilling experience no classroom lesson could have prepared them for. Yes, you have be there to get your hands dirty to find out.

You are probably wondering what they were supposed to do with the mud. In short, check out the bugs in the mud. Anything without backbone, isolate and identify them. These include insects, worms, snails and....

Bingo! The students scooped up half a dozen or so leeches! These are not your 1-inch wriggling critters commonly found in Malaysian forests. Imagine these half-foot whoppers* clinging everywhere on your body including those parts of your body not exposed to the sun, furiously competing against one another to feed on your blood.... blood chilling. And I have always believed that there are no carnivorous leeches in Singapore. There goes that belief. Never will I nonchalantly wade into an unknown pool/pond/reservoir here.


Is anyone screaming yet? Oh yes, the students were indeed screaming, not in terror but in excitement. I guess there is a big difference between seeing leeches in a sample bowl and having them stuck on your own body.

On the technical side, the presence of this significant number of leeches indicate a bad water quality with a low oxygen content. This was confirmed by our oxygen tests.

In case you conclude that I hate leeches, on the contrary, they are one of my favourite animals. Not the kind that you keep at home but the kind that you admire. Their tenacity and survivalability rank tops among animals. This is in addition to their arsenal of biochemicals that allow them to do what they do best - all these packed into a compact but ferocious package.

* These half-foot critters are fish fry compared to the half-METRE Amazonian leech.

Figures (L-R, T-B): Classroom lesson of looking at dead (and boring) specimens under the microscope; trying to score some live specimens in the field; mud and bugs are part of the job; searching intently for the tiniest bugs; cute aquatic leeches - are they carnivorous buffalo leeches?; check out my article on the chemical secrets of the leech in Singapore Scientist no. 111 (2008)

How mercury flows downstream

A comprehensive piece of research by USGS on the biogeochemistry of mercury in 8 different streams in US. Several interesting observations were made in the study but I will just highlight 2 points why mercury is an insidious pollutant posing a high degree of hazard.

1. The source of mercury in the study does not go directly into the water. Instead, mercury is carried by air or rain into streams and their watersheds. In other words, the watershed may not have any industry (e.g. mining, smelting, power generation) releasing mercury but mercury can still be transported from other areas by the atmosphere

2. Mercury can definitely move up the trophic levels to reach the top predator, usually fishes, if not man. It does not just remain in the abiotic environment, it can easily enter the food web right at the lowest level (e.g. algae) to affect the entire ecology.

How mercury flows downstream

via ES&T Online News on 3/11/09

A comprehensive study shows the correlations among landscape, mercury, and the life in streams and rivers.