1. Department of Environmental Engineering, Toyama Prefectural University, Imizu, Toyama, Japan
2. Graduate School of Gifu University, Gifu, Japan
3. National Water Supply and Drainage Board, Sri Lanka
4. Department of Civil and Environmental Engineering, Faculty of Engineering, University of Ruhuna, Hapugala, Galle, Sri Lanka
5. Department of Zoology, Faculty of Science, University of Peradeniya, Peradeniya, Sri Lanka