Peninsular diatom index for water quality monitoring

Formulation of a diatom index called Peninsular Diatom Index (PDI) based on nine environmental variables was developed to assess the water quality for Kabini River of Southern Karnataka. The selection of the variables was based on the Principal Component Analysis. Nineteen species of diatoms were identified from 144 samples using standard procedures. Sensitivity(s) and tolerance (v) values were calculated for each of the parameters and each of the species identified.PDI was calculated using the computational metric suggested by Blanco et al. (2012) About 4 species, Caloneis parvum, Nitzschia obtusa, Melosira islandica, Pinnularia gracillum and Synedra ulna indicated that the water quality was good. Only 5 species indicated that the water quality was acceptable, while 8 species indicated that the water quality was poor. Pinnularia divergens and Stauroneis angular indicated water quality as bad. The overall quality of the river was poor to acceptable (7.4). The PDI serves as an important tool for detecting water quality at regional level using local water chemistry parameter.