Request for additional information about Punggol and Serangoon Reservoirs

* Parts of the email have been removed for conciseness*

I read with interest about the blog posts which you have made about the newly opened Punggol Reservoir as well as the overall knowledge that you have about water quality monitoring. Given your enthusiasm and expertise in this field, we hope that you will be able to furnish us with some of the details that we require, such as:


- An overall idea of the environmental monitoring process

- The critical parameters which are monitored and their baselines [understand from Greenspan that, for water, this includes: Dissolved Oxygen (DO), Temperature, Turbidity, pH, Conductivity, Chlorophyll-a and Nitrate (NO3)]

- How often/when are samples collected for testing?

- Are there any typical steps taken if the baseline conditions are exceeded?


It would be beneficial if some of the information are specific to the Punggol/Serangoon Reservoirs.

T


Like all other reservoirs on mainland Singapore, Punggol and Serangoon Reservoirs (PSR) are under the purview of PUB. The water quality in these reservoirs is definitely monitored though little detail has been publicised - type of water quality parameters monitored, frequency of monitoring, results and implications of the water quality data.

You may want to try the following reference books to find out more about water quality monitoring

1. Water quality monitoring : a practical guide to the design and implementation of freshwater quality studies and monitoring programmes, edited by Jamie Bartram and Richard Ballance
   I find it useful as it covers the topic comprehensively though it may be slow reading at times. Published on behalf of United Nations Environment Programme, World Health Organization
2. Water quality assessments : a guide to the use of biota, sediments, and water in environmental monitoring (2nd ed), edited by Deborah Chapman
   This is a follow-up to the above title. Again, useful and comprehensive. Published on behalf of UNESCO, United Nations Educational, Scientific, and Cultural Organization, WHO, World Health Organization, UNEP, United Nations Environment Programme

You are indeed right. Dissolved oxygen (DO), temperature, turbidity etc. are relatively easy to measure and hence routinely monitored, probably around once a week (my estimate, feel free to dispute).

I am sure many other parameters are also measured. (Just look at the WHO drinking water guidelines - they have about 200 parameters.) For example, heavy metals, pesticides, oil, volatile organic compounds (VOCs) are good bets. Even the fancy ones like dioxins and radioactivity are possible candidates. Of course, the frequency of monitoring of these chemicals (and radioactivity) depends on the cost and effort of analysis (e.g. expensive lab instruments or tedious lab preparation steps are needed), the likelihood of these chemicals existing in our reservoirs and their impact on health and environment. I won't be surprised if some of the fancy parameters are measured only once a year.

The parameters monitored in our reservoirs probably exceed those given in WHO drinking water guidelines. And PUB is probably going into biological monitoring using macroinvertebrates (bugs). Check out my previous post, Water trends in the next decade, for more information on this topic.

Figure: Serangoon Reservoir with a dam in the distance. The dam serves to separate fresh water in the reservoir from salt water in the sea.

Figure: Punggol Reservoir with Sengkang Floating Wetland in the foreground




For water quality monitoring  (WQM) in our reservoirs, setting up limits for the water quality parameters can be a bit tricky. Do we apply drinking water guidelines to reservoir water? Probably not.

Or do we apply guidelines for aquatic life? Countries such as USA, Canada etc. already have such guidelines. Do we use their guidelines? Again, probably not as the environmental conditions are quite different between Singapore and say, USA. Even if we develop our own guidelines, I am certain every reservoir will be different from one another e.g. geology. How do we factor these differences into our guidelines? Hence, I always believe that baselines for each reservoir will have to be established based on long term WQM. Any deviation from those baselines may then be further investigated. As far as I know, PUB's guidelines (if any) for reservoir water quality have never been publicised.

Water quality monitoring workshop for CUGE

I had the opportunity to conduct an inaugural water quality monitoring (WQM) workshop for CUGE (Centre for urban greenery and ecology). The participants were mostly Nparks staff. Before this, I had only worked with MOE teachers and students in my WQM courses.


It was indeed an eye opener. With their outdoor experience, my field trip became a non-issue. No complaints about the mozzies, the mud or the weather.

In fact, I dare say this field trip to Ngee Ann Stream was my most challenging. A huge tree has fallen over the path I normally took my participants. There was no clear path through it or around it. Fortunately, a hardy participant (L) came forward to blaze a trail through the fallen tree while I was wondering whether the rest were able to handle such bashing through. Reminding myself these were Nparks staff, everyone came through without a scratch despite the big ants scrambling all over the branches in protest of our intrusion. A few other “garang” types helped to clear the trail as L and I took the lead in our trailblazing.

Because of the wet weather earlier in the day, the canal was flooded. Usually a convenient way to cover ground, the canal became out of bounds. Since these guys and ladies were as good as I thought they were, I decided to do another round of bashing through a patch of tall grasses. Since these were only grasses (not trees or shrubs), I used my handy walking stick to sweep the blockage aside. Problem solved.

Though most of the participants have no chemistry background, they were thrilled with trying out the water testing kits back in our classroom. Designed for field work and hence simple to operate, most participants took an instant familiarity with the kits’ usage. In fact, they were more than enthusiastic to stay after 5p.m. to finish their water testing with the kits. It is always a pleasure to observe students with a passion to learn and experiment.

Figure: My favourite monitoring station along Ngee Ann Stream. A good shady spot for the participants to rest after the "gruelling" hike through tall grasses and steep slopes. Notice the tall grasses in middle - we had to bash through those after this station.

Figure: This canal is normally dry with only a small flow in the centre. On this day, an earlier rain has made the canal impassable. Even the participant has to collect a water sample on the steps. Not for school students.

Figure: Using water testing kits back in the classroom

Figure: Participants putting up their water quality data for all to see and compare.

Figure: Bug hunting and identification at Chinese Garden

Figure: We had the rare chance of checking out what Chinese Garden has implemented its admirable efforts to go green. This is a phytoremediation project to treat and reuse grey water from a toilet's sinks.


Update: Here is the link for a write-up of the workshop on CUGE' website
http://www.cuge.com.sg/October-2011 > 04 Oct 2011 - A Fun and Enriching Hands-on Experience Sampling and Testing Water

Checking out the water quality at Singapore's iconic (but mostly forgotten) landmark: Chinese Garden

Some time ago, I was lamenting about the lack of water bodies in Singapore for educational activities. I now realise that I have missed out a wonderful outdoors location for my water quality studies and it is none other than our iconic Chinese Garden. (The nearby Japanese Garden and Jurong Lake Park should also fit the bill as outdoors classrooms though I have yet to check them out.) When I was younger (decades ago?), Chinese Garden was always in the spotlight for shooting of period drama serials by the then SBC (Singapore Broadcasting Corporation) (now Mediacorp). Nowadays, it is mostly forgotten except for a handful of joggers, photographers and tourists. The latest attractions in town are the sexy casino and theme park on Sentosa, as well as the panoramic sky garden and another casino at Marina Bay Sands.Chinese Garden is so "history".

What prompted me to check out Chinese Garden was a friendly meeting with the management of the Garden under JTC (Jurong Town Corporation). They are really supportive of promoting the 2 gardens and 1 park for educational purposes - outdoors lessons, water quality studies, even relevant R&D. Do approach them if you think that they fit your educational curriculum as I am sure they will oblige your request.

Enough chatter. Here are some of the findings on my trip there.

Figure: A rather commonly encountered aesthetic problem is the obvious presence of algae in a few streams and ponds. We didn't try doing any sampling for fear of allergic reactions to algae and their metabolic products.

Figure: Quite a few healthy patches of cattails. We tried sampling for bugs (macroinvertebrates) here as such densely vegetated areas are their favourite haunt.

Figure: A small water body at the dead end of a stream. Because of the lack of flow and circulation, the end of this pond is occasionally overwhelmed by suspended sediments. We also did a sampling of the bugs here.

Figure: Sorting out the bugs from our water sampling. Surprise, surprise... there are healthy populations of various bugs despite the aesthetic problems mentioned above. Lots of shrimps, damselflies, some dragonflies, quite a few mayflies, water bugs, almost no worms and no leeches. The water is biologically (and implicitly chemically and physically) healthier than most water bodies I have sampled in Singapore. Make no mistake, Chinese Garden is THE place to visit for water quality work.

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

Digging around at Pandan Reservoir

I managed to steal some rare spare time to tag along with a NUS team and JH for a biodiversity survey of the floating wetlands at Pandan Reservoir.
What floating wetlands?!? If you have been observant enough, Pandan Reservoir and Lower Seletar Reservoirs have several bunches of plants floating right in the water. No, they are not aquatic weeds that suddenly grow up from the reservoir bed. They were deliberately placed there as an experiment(?) to improve the water quality. (Check out my previous post on how plants can clean up water.)

Figure: One of the floating wetlands at Pandan Reservoir. Notice that the plants on the wetland are different from those on the shore.

These floating wetlands are actually made of a floating plastic matrix above which a layer of coconut husks is embedded. The plants are allowed to extend their roots through these 2 layers.

Will they float away? No. Short of an extreme weather event, each wetland is anchored to the bed by rocks.

These floating wetlands dotted the northern shore of Pandan Reservoir. Are they effective in improving the water quality? My opinion is there are probably too few of such wetlands to make a difference to the reservoir as a whole. (Did I say that this was just an experiment?) Any change in water quality is probably localised and restricted to the immediate vicinity of the wetland. You will likely need a series of these wetlands to ring the entire reservoir. Maybe add another ring or two.

Figure: By the way, we had the luxury of sitting in a PUB motorboat as we passed by several floating wetlands

Next question - do bugs (macroinvertebrates) live under these wetlands? If so, what kind of bugs? These are interesting questions as my usual bug surveys were performed in running water (e.g. stream) or stationary water (e.g. pond). In the substrate of a floating wetland?!? No one knows...

Figure: Digging and scrapping and sweeping through the underside of a floating wetland

Figure: Voila! You can see a Marble Goby (top left) and a shrimp (bottom right) clearly here.

No so clear in the figure include: backswimmers (many!), unknown zooplankton (?) (many!), copepods, chironomids (your wriggling blood worms), a few damsel flies, dragonfly nymph exoskeletons (surprisingly, no live nymphs though we can see adult dragonflies happily scuttling through the air), chironomid eggs and pupa cases, mayflies (!). Looks like the biodiversity in these floating wetlands ain't so bad.

Figure: No, this is not part of the wetland survey. Actually, this is the primary task of the NUS team - deploying sampling traps in the reservoir to find out what kind of bugs can be lured into them.

Figure: On the way back, we stopped by this odd looking contraption floating in the middle of the reservoir. (Actually, it a buoy housing sensors though no one in the team knows what kind of sensors.) Of course, data from the sensors are transmitted telemetrically to some receiver on shore. Everything is this package is powered by solar energy as evident by the solar panels. See a previous post on descriptions of a similar setup. Oh, we didn't stop here just to admire this blue box. The NUS team actually wanted to catch some spider specimens here as a healthy population of spiders seems to be thriving on this buoy in the middle of nowhere.

A quick update for the past months

I would like to convince myself (and you) that my packed work schedule has prevented me from posting anything since the end of May. I know it is a shame but I am also sure that inertia has played a large part - not having posted for so long propagates the said behaviour :-)

In part to prove that I am really "busy" and to update you on the past activities, here is a summary of my "work".

June - July
Conducted "Freshwater quality and biodiversity" course for Crescent Girls, Henderson Sec Sch, Clementi Woods SS, Queensway SS. It was back to a tributary (sort of a naturalised drain) of Sg Ulu Pandan for more water quality testing and bug hunting.

Figure: The group hunt (for bugs)

Figure: Don't forget the water quality parameters

Figure: Sorting out the spoils of the hunt

Figure: A rare find - freshwater eel - too small for unagi though

Figure: The common Dragonfly nymphs though perhaps not so commonly seen by the students

Conducted a round of 6-day intensive AEM (advanced elective module) "Water quality and pollution".

Figure: On first sight, nothing wrong with the scene. But if you look closely enough, lots of people are looking down on their pants and shoes. This is what happens when you venture out in the wilderness in the rain and through knee high vegetation. All manner of creepy-crawlies are out their homes, latching on to the hapless passer-by (i.e. us).

Figure: Part of Ngee Ann Stream. Looks like another canal except that this used to be a natural stream with thick secondary forest on both edges. See next figure.

Figure: The same part of Ngee Ann Stream as the figure above but a year back. Note the vegetation stretching right to the edge of the secondary forest stream

Figure: An unusual find - a catfish struggling against the current in the "canalised" Ngee Ann Stream. Why was it doing so? I have no idea. Perhaps it should have just flowed along with the tide of change as what the rest of the stream did when it gave way to "development".

Figure: Due to the earlier heavy rain (what else is new in Singapore?), the whole canal was flooded, preventing the students from sampling the water (too dangerous).

Figure: The same part of the canal as the figure above but in drier times and more than a year back.

Figure: I simply can't resist putting in this routine group photo. Must show that the participants are in good spirits, right?

Singapore International Water Festival (27 Jun 2010)

Once again, I was roped in to organise the event "Amazing Greenviron Challenge" - an environmental quiz of sorts with indoor and outdoor components at the Marina Barrage. Weather was terrible in the morning so the outdoor part has to be moved indoors. (Right, rain was indeed heavy in June, giving rise to the shocking floods in downtown Singapore.)

Figure: Only 1 photo to show you here - the super group photo with organisers, student helpers and participants.

(Are we not done with the summary yet??? Afraid not... Did I mention that I had a tight schedule then?)

Water Quality Monitoring (WQM) (19 Jun 2010)

Amidst the tight schedule, I managed to sneak in a round of WQM with Team Seagrass at Chek Jawa.

Figure: On this rare sunny June morning, my students prepared their equipment for WQM.

To top it off, I attended the 4-day Wilderness Medical First Responder (WMFR) Course by OBS (Outward Bound Singapore) on Pulau Ubin. More on this in a later post.

Figure: WMFR participants and our dummies

WQM at Pasir Ris

Ah yes, the problematic kid on the block with regards to water quality - Pasir Ris Beach. (The latest advisory on its "fair" water quality is found here.) We checked out this notorious locale on this rainy July morning. Perhaps unknown to most people, this stretch of sand hosts 2 significant patches of seagrasses even though they are not monitored by Team Seagrass. (Some of the Team's members do however check out the seagrasses here in their own capacity.) And since there are seagrasses here, my team will of course be interested in the WQ.

Figure: 1 patch of seagrasses near Sg Loyang

Figure: The 2nd patch of seagrasses near Sg Tampines. I was told that there is a smaller patch further west near the end of Pasir Ris Park. We did not check this one out though.

Myth or miracle? - Using 1-cent coins to destroy mosquito eggs

The following email about using the Singapore 1-cent coin (another version uses the Malaysian equivalent) to stop mosquito breeding has been circulating around. At first glance, this appears unrelated to water quality but read on... and find out another aspect of water quality and macroinvertebrates (bugs) that we seldom think about. (The common theme is about how clean water is indicated by a healthy bug community while polluted water is often dominated by the "uglies" such as leeches, tubifex worms.)

---------
Subject: How to prevent mosquitoes lay eggs, cheapest way of preventing survival of mosquitoes.


We cannot stop mosquitoes laying eggs at any stagnant water in drains/ponds or water collected in waste pails, tanks, tins, used tyres etc. etc. Of course if you have fish inside the tanks/containers then there should be no problem.


Do you know that there is a very simple and very economical way to destroy the mosquitoes' eggs and not let them hatch into larvae. Very very simple, just put in few 1 cent copper coins into the tanks/containers then it will solve all your problems.. Because in accordance to Japanese Research Scientists, they found the mosquitoes eggs will be destroyed by a kind of mineral discharge from the copper.


DON'T BELIEVE, Try it by yourself and even the small snails also will not visit the containers (with copper coins) collected with stagnant water. You will observe the water collected in the containers will be very clean and clear.
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Should you save up your 1-cent coins to keep the mozzies away? (By the way, production of 1-cent coins has been discontinued some years back due to inflation.) Here's my take:

Certain heavy metals (e.g. copper, lead) have been known to be toxic to bugs and their larvae in water (selected ref: 1, 2). These heavy metals exert their toxicity when they are dissolved in water at concentrations as low as below 1ppm (part per million).


The Singapore 1-cent coin is made of zinc plated over by copper according to the Singapore Mint. Solid copper is barely soluble in water but under certain conditions (e.g. acidity), significant amounts of the copper plating can dissolve into solution. With a sufficient concentration of dissolved copper in water, mosquito larvae (or eggs which are usually more vulnerable) can be killed.

Is the water then safe for drinking? It depends on the final concentration of dissolved copper. WHO (World Health Organisation) provided a maximum limit of 2ppm (2004 guideline) of copper in drinking water. But pouring the water into the sewers should not pose a problem.

Myth or miracle? Neither, it is science. No harm trying but I wouldn't count on this method as my only defence against mosquito breeding.

You can also read my interview on this topic in Lianhe Wanbao (4 Mar 10).

Water quality monitoring (WQM) projects on the rise?

It is heartening to see more schools (secondary and pre-U) getting into water quality monitoring (WQM), based on the queries coming in from teaching staff and students. This is especially encouraging given the lack of publicity and media coverage on WQM.

I will truly be happy when I see the same trend in research and innovation funds going into WQM. On the positive side, there is already an observable rise in interest in environmental issues, the most obvious star being climate change with all its implications.

Much money has also been poured into water - not WQM of course but on water and wastewater treatment. In the context of Singapore, this is understandable as water has always been an issue of national security. Wastewater treatment may seem to to be a poor cousin of water supply but it is NOT. Without it, Singapore will likely be infested with filthy waterways and crippled by rampant waterborne diseases. (I suddenly remember this analogous joke about our bottom orifice being the boss among all the other body parts. When it refused to work and shut down (literally), the brain, heart, stomach etc. went into panic and finally acknowledged it as the boss.)

Hopefully, we will start to recognise the role WQM plays in our water supply. Water does not only come from rain dropping into the reservoir directly. It comes from the watershed serving the reservoir. In Singapore's case, the watershed can extend to quite a large area serviced by a network of canals running into the reservoir. Oh well, perhaps one step at a time.

I have copied an excerpt of a recent query below together with my reply. Perhaps some of you may find it useful. (I have of course omitted names of persons and schools in my excerpt.)

-------------------------
We are a group of 3 students from (omitted) currently preparing to embark on a water quality project by assessing the macroinvertebrates in water body. The two main water bodies we are looking at are WELL stream and a canal in Hort Park.


After looking at your blog, we discovered a lot of useful information that can help us with our project. There are a few problems we hope you can clarify for us.

Firstly, we are unsure about the period needed to monitor the macroinvertebrates in order for the results to be accurate.

Also, we are not very sure about the suitable methodology to monitor the macroinvertebrates as we are strongly discouraged to remove macroinvertebrate from the water bodies. Currently we are thinking about scooping the macroinvertebrates out of the water body to observe, before putting them back since the canal and stream are relatively shallow and the kick-seine method is not practical. The problem with this is that the stream may flow too fast for us to count the macroinvertebrates correctly.

We really want a guidesheet and would like to enquire if you have a guidesheet for identifying macroinvertebrates. Due to short dateline, we would only pick on one species to observe, which we would only decide after going to the actual sites.

-----------------------------

Good to see that you are interested in the bugs in our waters.


A few points from me:

What is your objective of assessing the bugs in your chosen water bodies? Do you have a hypothesis to prove or disprove?

Monitoring period
This depends on your answer to point 1.


E.g. if you are trying to find out the effects of day/night on the bug community, then you probably have sample in the morning, afternoon, evening, after midnight.


Or are you trying to correlate some other parameter to the bug community?

 Methodology
This will be tricky if you do not want to remove any bugs from the environment. Sorting and counting will be impossible without bringing the bugs out of the water though I believe it is possible to sort/count on site as your suggested (the bugs will still have to be removed from the water environment).

However, the method you suggested (scoping out and putting back) may not work too well if you do not stir up the bottom sediments. Most bugs are found in the sediment.

Being not familiar with the locations you mentioned, I am not sure why you said that the kick seine method is not practical as it can still be used in shallow waters. Other methods include the Surber sampler, colonisation samplers (leaving something in the water for bugs to colonise) and drift sampler. Colonisation sampling and drift sampling do not require kicking and have a good chance of yielding a signicant number of bugs.

I suggest that you restrict yourself to Order level for identification rather than species level as it is difficult to even go to Family level in the field. A good guidesheet is the Aquatic key sold at Nature Niche. It is designed for Thailand's bugs though it should still work well here. Check if they have stock. If not, you may borrow from me.

Singapore Bug List

In response to queries from some readers regarding the types of bugs (macroinvertebrates) found in Singapore's fresh waters, I have compiled a quick list of the bugs I have encountered.

I have broadly classified our fresh water bodies into 3 types:

1. Ponds

Figure: A very stagnant pond next to Sungei Ulu Pandan

Figure: Turbid pond in the forest near Dover MRT station. (Sorry folks, if you intend to visit this one, forget it as the whole area is now under construction.)






Bugs present:

1. Leeches! And big ones too! These are whoppers compared to the tiny terrestrial ones commonly encountered in Malaysian jungles. I was told that they are Buffalo Leeches (unverified).
   
   There are also tiny ones (fingernail sized).
2. Dragonfly
3. Damselfly
4. Water stick insect
5. Mayfly
6. Pond skater
7. Chironomid ("Bloodworm")
8. Sludge worm
9. Beetle

NO Caddisfly!

Unsurprisingly, when the dissolved oxygen (DO) level drops low (say below 2-3mg/L), the ponds become infested with leeches which crowd out the friendly bugs e.g. Mayflies.

2. Streams

Figure: Ngee Ann Stream riffles surrounded by secondary forest then. If you want to visit this wonderful stream, do it soon because the adjacent land is cleared and under construction (yawn, what else is new?). Who knows when the stream will be paved over to make way for yet another condominium?

Figure: Binjai Stream. A good old clear stream PROVIDED rains do not wash sediments into it.

Figure: Tributary into Sungei Pandan. This is a good example of a canal that looks like a natural stream.

Bugs present:

1. Snail (lots of them in the tributary leading to Sg Pandan)
2. Collembola
3. Dragonfly
4. Damselfly
5. Eel
6. Shrimp
7. Crab (Binjai Stream. Yes, this stream is clean and natural enough to find crabs.)

NO Mayfly! NO Caddisfly!

3. Freshwater reservoir

Figure: MacRitchie Reservoir. Fully exposed to the sky.

Bugs present:

1. 
   
   Mayfly
2. 
   
   Dragonfly
3. 
   
   Damselfly
4. 
   
   Chironomid
5. 
   
   Shrimp
6. 
   
   Snail
7. 
   
   Lentil Shrimp
8. 
   
   Caddisfly

NO Leech!

Disclaimer: Haha, this is definitely not a complete list. All the above bugs are based on my experience in those waters.

Strangely, NO Plecoptera (Stonefly) and Megaloptera have been found so far in Singapore waters! These 2 orderse are supposed to be really common in other countries e.g. USA, UK.

Acknowledgement: Many thanks to Esther for introducing me to the world of water bugs! I am still learning lots more from her.

One last comment:

Forget about finding bugs in artificial fish ponds with little or no natural substrate - e.g. below