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SEPG 2235 - Date Awarded 2003
Monitoring water quality in springs of the Nepalese Middle Hills using diatoms
Bed Mani Dahal & Ingrid Jüttner
Abstract
A survey of 30 springs in the Jhikhu Khola watershed of the Nepalese Middle Hills was conducted in December 2003 to investigate diatom assemblage composition and diversity, to obtain information about physical, chemical and microbiological conditions, and to link diatom biodiversity pattern to ecological conditions. The Jhikhu Khola watershed is densely populated and the major land use is irrigated agriculture. The water quality of the springs has deteriorated rapidly over the last decade and there is a need to develop a method using biological indicators to provide an integrated assessment of their environmental conditions. Spring water chemistry varied considerably and nutrient concentrations were often high with nitrate concentrations between 0.3-48.7 mg/L and phosphate between <0.05-0.565 mg/L. All springs were acidic with pH values between 4.5-6.5. In total 67 diatom species were found. Species richness was low and most springs had between 9-13 species. There were large differences in assemblage composition between sites. Eunotia rhomboidea, an unidentified Eunotia species and Pinnularia cf. obscuriformis were common at low pH, while sites with higher concentrations of Cl, NO3, Ca and Na were characterised by higher abundances of Navicula minima, Sellaphora seminulum, Navicula cf. absoluta, Achnanthes rupestoides and Nitzschia cf. inconspicua. These data show that diatoms respond to major trends in water chemistry in the springs of the Nepalese Middle Hills and can be used to develop tools for monitoring water quality problems such as eutrophication and acidification of these ecosystems.
Full report SEPG2235
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