Increased Prevalence of Indicator and Pathogenic Bacteria in the Kumarakom Lake: A Function of Salt Water Regulator in Vembanadu Lake, A Ramsar Site, Along West Coast of India

Prevalence of indicator bacteria such as Escherichia coli and pathogenic bacteria like Vibrio Cholerae, Vibrio Parahaemolyticus and Salmonella were analysed in Vembanadu lake (9035'n 76025'e), along the west coast of India for a period of one year (October 20042005 September). Estuarine water samples were taken monthly from ten stations on the southern (inside bund region) and northern sides (outside of the bund) of a salt water regulator constructed in Vembanadu lake. The results indicated that substantially high level of indicator bacteria within the bund region of the lake during monsoon months and at the time of closure of the bund than the northern region. The results highlighted, that the water body is polluted with high faecal colifrom bacteria with mean mpn value ranged from 1718-7706/100 ml. E. Coli, V. Cholerae, V. Parahaemolyticus and Salmonella serotypes such as S. Paratyphi a, b, c and S. Newport were consistently isolated from all the station. To our knowledge this is the first report on the isolation of these Salmonella serovars from this lake. E. coli showed highest percentage of incidence (85.6-86.7%) followed by Salmonella (42-57%). V. Choleare (40-45%) and V. Parahaemolyticus (31.532%). The increased prevalence of indicator and pathogenic bacteria within the bund region may be due to the altered flow patterns due to the salt water regulator. The results of the present study suggest that the high faecal Coliform density and pathogen concentration in this water body will pose a serious health hazard to those who use this system for fishing and recreation.