Prevalence of pollution indicator and pathogenic bacterial load in a tropical estuary, Bay of Bengal: a multivariate statistical approach

Abstract

The present study aimed to estimate the current level of pollution, human pathogenic bacteria and their seasonal variability of the Dhamra estuary. The hydrological parameters like water temperature (WT), pH, salinity, dissolved oxygen (DO), nitrite (NO2-N), nitrate (NO3-N), ammonia (NH4-N) and phosphate (PO4-P) were studied to understand its influence on the microbial community. The total viable count of bacteria in water (TVC-W), sediment (TVC-S), Escherichia coli in water (EC-W) and sediment (EC-S) and Streptococus faecalis in water (SFLO-W) and sediment (SFLO-S) were analyzed in order to distinguish the pollution indicator bacteria in Dhamra estuary. The collected data was inferred through person correlation matrix (PCM), principal component analysis (PCA) and Euclidean distance cluster. The results reflected that the bacteriological community had a significant correlation with hydrological parameters during pre-monsoon than post-monsoon and summer. Cluster analysis showed a positive link between the environmental variables. The result of PCA showed 6, 5 and 5 factors during pre-monsoon, post-monsoon and summer accounts for 86.83%, 87.81% and 85.62% respectively of the total variance. The estuary shows that both water and sediment were having a significantly high number of EC and SFLO in water and sediment and exceeded the permissible limits of the World Health Organization (WHO). The result shows that the estuary is under threat due to a load of pollution and pathogenic bacteria.