Studies on heterotrophic bacteria and total coliforms in relation with environmental parameters of water in Gurupur Estuary, off Mangaluru, Karnataka, India

Abstract

The physico-chemical and microbiological characteristics of water along Gurupur estuary Mangalore, Karnataka were studied for eight months from October 2014 to May 2015. Four stations selected in the estuary are near Kuluru Bridge (Station 1), the Konkan Seva samithi bridge where sewage discharge point is located (Station 2), the Sultan battery area which receives organic waste from few seafood processing industries (Station 3) and a confluence point of Netravati and Gurupur estuary near old port (Station 4). The minimum and maximum values of Total Heterotrophic Bacteria (CFU x 10 7 /mL) varied between 0.063 to 930, 0.39 to 440, 0.01 to 65 and 0.005 to 71 at Station 1, 2, 3 and 4 respectively. Total Coliforms (MPN/100 mL) in water varied from 10 to 290, 9 to >1100, 10 to 460 and 10 to >1100 respectively at Station 1, 2, 3 and 4. The Faecal Coliforms in water (MPN/100 mL) ranged from 3 to 290, 4 to >1100, 3 to 240 and 10 to >1100 at Stations 1, 2, 3 and 4. Seasonally, THB, TC and FC counts were reduced from post-monsoon (October) to pre-monsoon (May) in all the stations. Both THB and TC exhibited positive significant correlation with dissolved oxygen. However, both THB and TC showed a negative correlation with pH, salinity and water temperature. The study on heterotrophic bacteria and total coliforms provides baseline information for decision makers and resource planners and would be a useful tool for further ecological monitoring and assessment of this estuary.