Jayzon G. Bitacura
Microorganisms like bacteria are frequently used as indicators of water quality in freshwater ecosystems. Thus, this study was conducted to evaluate the total coliforms (TC) and total aerobic heterotrophic bacteria (TAHB) present in the upstream (Kantagnos), midstream (lgang), and downstream (Kan-ipa) of Pagbanganan River. The most probable number (MPN/100 mL) of TC was determined through multiple tube fermentation test while counts of TAHB present in both water and sediments were enumerated by serial dilution and plating methods. MPN of TC revealed that the river water should not be used as a source of public water supply and as a venue for contact recreational activities like bathing and swimming. Furthermore, TAHB in the sediments of the river did not differ significantly across sites although their values showed a decreasing trend. Conversely, TAHB in the water column of the river significantly increased from upstream to downstream. These results are most probably influenced by the quarrying activities present in the area. In the upstream where there is no quarrying activity, TAHB was higher in sediment than in the water, while in the downstream where quarrying activities are present, it is otherwise. Because of these significant differences, it is believed that the ratios of TAHB present in the water column and sediments are potential indicators of sediment disturbance in the aquatic environment. The results of this study imply that proper management of Pagbanganan River by all sectors of the community is needed to keep it sustainable for safe use.
Keywords: indicator bacteria, water quality, freshwater ecosystem, anthropogenic impact