Preliminary assessment of the water quality of Rushikulya estuary based on the abundance of pathogenic bacteria

Abstract

Estuaries are among the most dynamic ecosystems in coastal regions and are facing serious threats due to increasing anthropogenic activities. The aim of the present study is to evaluate the water quality of the Rushikulya estuary by analyzing the abundance of pathogenic bacteria in both its water and sediment. Water and sediment samples were collected from five different stations at the mouth of the Rushikulya estuary during the monsoon and post-monsoon seasons. These samples were analyzed to assess the abundance of pathogenic bacteria and environmental parameters. The results revealed that bacterial abundance is significantly higher in the sediment than in the water, possibly due to a longer residence time of pathogenic bacteria in the sediment. Seasonal observations indicated an increase in pathogenic bacterial abundance during the monsoon season, suggesting an impact from monsoonal discharge. Escherichia coli-like organism, faecal coliforms, Shigella-like organisms, and Vibrio cholera-like organisms were the dominant pathogenic bacteria in both the water and sediment of the Rushikulya estuary. The higher abundance of these pathogens and the results of statistical analysis, which showed a strong correlation between Total Streptococci and BOD (r = 0.79), indicate the influence of human settlement and the mixing of untreated sewage in the Rushikulya estuary. The elevated levels of E. coli, faecal coliforms, and Shigella-like organisms in the Rushikulya estuary raise significant concerns that require immediate attention.

Keywords: Pathogenic bacteria; Pollution; Rushikulya estuary; Seasonal; Water quality.