5. Conclusion

            The rapid bio-assessment protocol of odonates showed the potential value of non-exhaustive surveys. It has the advantage of being efficient, effective, low cost, and easy to implement. At a regional scale, rapid bio-assessment is already used for bio-diversity assessment such as the African Freshwater Biodiversity Assessment (Oertli, 2008). The protocols developed can be easily be adopted by informed volunteers, amateurs, and hobbyists. Such an arrangement can involve more people to contribute as environmental activists. 

Although the use of this method of water quality assessment seemed practical, there are certain limitations to the use of this method. The first limitation was that the species of odonates used were only applicable to the Upper MacRitchie Basin of the Central Catchment area as the habitat there is unique to itself. Secondly, as the sampling was only done over a limited period of time, a more exhaustive measurement of odonates must be made so that a more complete inventory of odonate species can be made to see the extent to which these preliminary results can be generalised. This will allow a more comprehensive matrix to be developed to make a more reliable estimate of the water quality.

Although the use of odonates as a water-quality assessment tool has its advantages, odonates should not be sole bio-indicators of water quality. The use of other groups of macro-invertebrates, as well as chemical methods, may give a more reliable diagnosis than just one species. The complementary use of various bio-indicators can allow an initial estimation of the ecological health of fresh water resources to be determined before a more accurate method of measurement could be made by the Public Utilities Board or the National Parks Board.

            Further investigation and development of environmental assessment matrices could be done for other areas in the Central Catchment Area such as the Nee Soon Swamp Forest Basin, the Pang Sua River Basin and the Lower and Upper Peirce Basins. However, as some parts of the basins are within the Military Training area and some have been overtaken by expressways and other developments within the Central Catchment and its fringes, sampling odonates for environmental monitoring may not always be feasible. Meanwhile, the Upper MacRitchie Basin remains as a good site for us to test our hypothesis about how the odonates could be an indicator of the state ecological health of our freshwater resources.