14 April 2012

Chemicals sprayed at Chek Jawa

Today I saw a pair of NEA officers spraying chemicals to control mosquitoes at Chek Jawa.
They sprayed along the Mangrove Boardwalk, and got off the boardwalk to spray along the rocky shore as well.

I followed them for a while taking photos of what they were doing. Oddly (to me), they did not check the area until they got to the mangrove boardwalk. They then checked and sprayed the ground near the Jejawi Tower.
They sprayed all around the base of Jejawi Tower and all along the Nipah palm area.
They walked the entire back mangrove portion of the Mangrove Boardwalk and sprayed to the left and right of the boardwalk. There didn't seem to be much checking for mosquitos before spraying.
I fondly call this stretch of the boardwalk "Mosquito Valley". It is indeed full of mosquitoes, but also very rich in marine life which is easily seen by the smallest child!
The NEA officers sprayed all along the boardwalk until they got to the coast. When they got off the boardwalk and started to the spray the back mangroves further.
They did this area quite thoroughly.
I was surprised to see them get off the boardwalk and start to check and spray the natural rocky shores that are usually submerged at high tide.
They even checked the pools below the mid-water mark. Whatever is sprayed here will simply be washed into the rest of the shore at the next high tide.
I saw them heading towards the rest of the rocky shore, and had to leave as I was here to help guide at the Naked Hermit Crab walk.
Later on, I met them coming off the rocky shore before House No. 1. I was heartened to see that one of them removed some large litter from the shore. The officers were friendly and seemed professional in their job. They are probably just carrying out instructions.
The area I saw them spray is marked in blue. I think they did the entire rocky shore until where I met them again at the blue spot marked 'End'.
More photos of what I saw in this slide show.
I overheard them saying they plan to fog the area as well. I met some students doing research who said they saw NEA spraying on another occasion as well.

I'm not sure what chemicals are used in the spray. During the walk today, I could smell the sharp kerosene-like odour of the chemicals all along the Mangrove Boardwalk. I wonder if the chemicals will in fact cause an imbalance in the ecosystem that will eliminate natural predators of the mosquitoes and just make the mosquito problem worse?
I think this action was probably taken because of complaints by visitors of mosquitoes. Park managers often have to balance such complaints with the need to protect biodiversity.

Indeed, the mosquitoes at Chek Jawa can be abundant and fierce especially in the back mangroves. But the Naked Hermit Crabs so far have not had much problems. We alert our visitors to be prepared with repellent, and we ourselves dress in longs to minimise bites. The back mangroves is among our favourite stretches with much marine life. And the rocky shore and area adjacent is full of life too. More of what I saw today.

I have spoken to the NParks officers managing Chek Jawa. They say NEA is only supposed to conduct mosquito control on areas not affected by the tides and they will speak to NEA about this. But even in areas above the tidal influence, wildlife such as wild boar may drink the freshwater. Today, I saw the friendly Mama wild boar with her seven piglets and two older offspring hanging around Chek Jawa as usual.
Instead of spraying chemicals on the shore, it would be less damaging to the environment if perhaps visitors could be alerted to expect mosquitoes in certain stretches of the boardwalk? Or if repellent could be sold at the Information Kiosk?

If you can suggest constructive ways to manage this issue, please do leave a comment. Please make polite and constructive comments. I intend to send the link to this post to NEA and NParks as public feedback from those of us who feel spraying chemicals in a special habitat like Chek Jawa is not an ideal solution.

Comments are moderated. Please do not leave anonymous comments.

Thank you.

[Update 8 May 2012: I just received NEA's reply to my correspondence to them and NParks on the issue]


  1. Spraying chemicals can hurt the ecosystem especially if its along the shoreline! First of all non-target insects that are important pollinators or food source of other animals like frogs, lizards, birds will all be exterminated, leaving no food for the insectivores. Secondly the spraying seems to be done so near the shore that it will leach into the marine environment and kill the marine life which was the main reason why Chek Jawa was conserved in the first place. We all understand the need to control mosquitoes as vectors of malaria and dengue but to do it this way would do more harm than good. I think the sprayers need to be trained to spray the insecticide away from the shore and target areas that trap only freshwater and not seawater.

  2. Now I know what those oil patches on the water are.... That aside, I'm quite surprised that such activities are carried out Chek Jawa. I truly wonder how the animals are taking it. I believe that such spraying would affect the non targeted species since they might be affected by the fumes of it. A couple of times I've walked along the broadwalk and more often than not, I got to see other insects and I wonder how they'd be affected by the spraying.

    May I suggest that instead of spraying such chemicals, could we think of ways to increase the population of the natural predators of these mosquitos? I believe that this's a better way since it would control the mosquito population without the use of chemicals

  3. I wonder whether any research has been done, or any consideration given as to how these chemicals may affect the ecosystem of CJ? If chemicals MUST be used, I feel that their effects must first be well understood, and the type of chemical used should be chosen carefully to minimize negative impact on other wildlife. I believe many chemicals do not discriminate between mosquitoes and other organisms that are important members of the ecosystem. Also, like lekowala said, i'm quite shocked that the spraying is done so near the shoreline where it will definitely enter the marine ecosystem.
    I feel that visitors to these wild places, should expect that mosquitoes will be part of the experience. We can all do simple things like apply mosquito repellent to protect ourselves from mosquitoes.

  4. As a mother of 2 young children, we recently went on a tour to Chek Jawa and prepared ourselves with repellent, understanding that there will be mosquitoes in the natural habitat (which is one of the very last we have in Singapore).

    Even though we all got biten by the little 'commandos', we enjoyed the entire tour and being part of the rich nature.

    Denver (8 yr old): I think we should not spray chemicals as it will destroy the habitat of many creatures.

    Visitors who wish to visit Chek Jawa just need to understand and be informed on the mosquitoes in the area. Prepare insect repellents and wear long sleeve if necessary. Chek Jawa is a natural environment where we can learn a lot and we should respect and conserve the eco-system.

  5. By increasing the natural predators of the mosquitos, we may disrupt the mangrove ecosystem as mosquitos may not be the only food source for these predators. A better solution would be raising the awareness of the visitors that mosquitos are part of the food web in this ecosystem and getting bitten by them is part of the experience for this trip. if they are afraid, as visitors, they should apply insect repellent to avoid getting bitten by insects. We should learn to respect the nature and not to take it on them.

  6. I am shocked. Spraying insecticide at Chek Jawa reflects a certain amount of stupidity and/or disregard to the fragility of the ecosystems there. It also reflects a certain laziness and a severe lack of creativity in problem-solving capabilities.

    I wonder if any research has been done by whomever who had authorised the spraying of these chemicals, to assess the impact of these chemicals on the flora and fauna there, or if the spraying of these chemicals are effective in helping to control the mosquito population at Chek Jawa, in the first place. Chek Jawa, after all, is only a small part of a larger Pulau Ubin.

    I sincerely hope that this spraying would be discontinued until further studies can be done. Chek Jawa is a precious natural heritage for all Singaporeans, too precious to be sacrificed by the lack of thinking.

  7. As rightly mentioned, NEA is perhaps just doing their job and responding to the public's feedback. However, the application of chemical pesticides to such a nature trove will do more harm than good in the long-term especially if natural predators of the mosquito larvae are to be killed in the process of pesticide application. It would the the public's responsibility to be well prepared (mosquito repellent) and appropriately dressed (light, long sleeved shirts and long pants) for such conditions. Educating the public on 'why chemicals and pesticides are not used in Chek Jawa' can also be used to help Singaporeans understand the ecology of our natural habitats.

  8. What is a nature walk without mosquito bites, with them flying around you and irritating you throughout the journey, getting you to touch your skin and scratch them and leaving all the "kiss" marks at various spots?

    If they are trying to stop dengue from spreading, them perhaps they have come to the wrong place. Unless the mosquitos at Chek Jawa bite visitors who are infected with the dengue virus. (Mosquitos are just organisms that spreads the virus. They are not the creators of dengue.)

    Mosquitos contribute to the stability of our ecosystem. The dragonflies feed on them. At Chek Jawa, I hardly notice any dragonflies fly around. The uncommon mangrove dwarf (Raphismia bispina) is classified as rare to me. There used to be many of such male species (blue in colour) flying around when I started guiding in 2009/2010. However I can hardly find a single dragonfly in Chek Jawa. http://peiyansama.blogspot.com/2010/12/mangrove-dwarf-chek-jawa.html This is the only image I have captured at Chek Jawa on 24 December 2010.

    Dragonflies provides indications as to how well the ecosystem of the place is doing.

    Mosquito control should strictly be confined to urban areas. Leave our nature parks and wild places alone.

    What is a nature walk without mosquito?

  9. One needs to know and understand that mosquitoes are permenant feature of all coastal wetlands.

    The basis to the abundance of mosquitoes in these areas is easily explained by the existence of relatively stagnant tide pools which are formed during a high tide and would only flushed away by the next high tide. In Singapore (correct me if I am wrong), the time period between two high tides are 2 weeks-since Singapore's water experience diurnal tide conditions. Therefore, these tide pools will not be not flushed by the daily tide movements unless the high tides wash the pools away -this promotes mosquito breeding within these pools.

    Therefore, fogging these wetlands(with assumption that the 'chemicals' used are environmental-friendly)would not be the 'best 'ultimate solution to control the mosquito population. One would need to change the hydrology of the areas i.e. to prevent formation of tide pools if he/she really desires to get rid of the mosquitoes in the mangroves-this is almost impossible to be carried out especially on rocky shores!

    Ecology wise, the removal of the mosquitoes would lead to devastiting effects of food webs in these areas. What will happen to population of insects, lizards or other mosquito eating organisms within these wetlands if there is no lack of food for them. This in turn, will affect the other animals' diet who feed on the mosquito-eating organism- i.e. the domino effect and the collapse of the food chain.

    In summary, NEA should just avoid fogging. it's harmful to other organisms both physiologically and ecologically(as mentioned by other commenters). If the situation is indeed dire, I'm sure there other more environmental friendly options to deal with them.

  10. For goodness sake, it's NATURE... let it be.

    When we humans try to control or affect nature, it oftens come with a backlash and will cause even more problems in the end. With such fogging and spraying, the rest of the insects and creatures which may have helped to control the population of mosquitos and other creatures down will be greatly affected (by lack of food or simply killed off by these chemicals) and in the end they will not be able to re-populate as quickly as moquitos to control them later on.

    Please stop the un-necessary and just remind users of the area to protect themselves accordingly instead.

  11. It's certainly very distressing to think about the potential impacts on the wildlife and other organisms in the area, especially in areas that don't actually have a mosquito problem.

    I don't blame the workers because they're doing their job and carrying out instructions (although they seem to be quite overzealous), but it's a matter of the instructions they receive from higher management. At the same time, it's essential to get visitors to understand that mosquitoes, while undesirable, are inevitable in nature areas. Instead of complaining to the authorities and getting them to poison the area with chemicals, how about taking the necessary steps to reduce the risk of getting bitten?

  12. I agree with PeiYan: "Dragonflies provides indications as to how well the ecosystem of the place is doing". If I come to a site and I see a variety of dragonfly species which are typically found in a similar habitat, then I can say that the ecosystem there is rather healthy.

    Well, in Bishan Park where grass cutters are seen cutting grass (http://www.youtube.com/watch?v=mbo8MShHYxQ) and mosquito oil is applied (http://www.youtube.com/watch?v=UT0iVjMkoMw), I still only see 4 or 5 species, much fewer than I had expected.
    Well, we have given feedback to NParks and PUB. It seems that the grass cutters do not cut the vegetation so thoroughly now. That's better than before. But I still wish to see more vegetation, and a variety of vegetation along the stream. As for mosquito oil, PUB replied to say that they will use BTI (Bacillus thuringiensis israelensis, a soil bacterium) instead.

  13. How can we introduce insecticide and fog in a natural habitat?

    If the chemical used is Cypermethrin (which is commonly used in fogging), even though it has a low toxicity to birds and mammals, they are highly toxic to aquatic organisms and fish as well as to bees. The spraying is in the coast at Chek Jawa!

    Highly sadden by this.

    In Taiwan, my sister send me a picture of a sign in the toilet that warns visitors to be aware of poisonous snakes. It is a given that in a natural environment we protect the wildlife residents of the area by taking precautions ourselves and not kill the residents.

  14. Thanks to your many constructive comments, NParks replied almost immediately to my email this morning about the incident. They will arrange to meet NEA to discuss this. NEA has also just replied to say that the issue has been highlighted to their officers and that they will respond as soon as possible. Thank you everyone for your support on this issue!

  15. I strongly agree with all to protect the wildlife...mosquitoes too...
    Instead of using chemicals on the environment, use it on ourselves. Be prepared with mosquito patches, use as many as you like as long as you take the patches out as you exit the park. Often a time, i notice used mosquito patches on the ground.
    NEA should spend more time clearing and preventing garbage from drifting in at the shoreline and also educate island residents on garbage proper disposal in the plantations. I was there exploring the plantaions and was much disgusted by the sight of loads of garbage.



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