RELATIONSHIPS BETWEEN INDICATORS, PATHOGENS AND WATER-QUALITY IN AN ESTUARINE SYSTEM

This study examined water and sediment samples for a range of indicato r and pathogenic microorganisms from six sites in an urban estuary, Sy dney, Australia. Water quality was affected by rainfall and sewage ove rflows which were associated with significant increases in the concent ration of faecal coliforms, faecal streptococci, Clostridium perfringe ns spores, F-RNA bacteriophage, Aeromonas spp., Giardia and Cryptospor idium spp. However, in sediments, only faecal coliform concentrations were significantly increased by rainfall, although sewage overflow aga in resulted in increased concentrations of faecal coliforms, faecal st reptococci, C. perfringens spores and Aeromonas. Isolation of Salmonel la appeared to coincide with wet weather events and occasionally ident ical serotypes were detected in sediments at several locations within the estuary. However, isolations of enteric virus were sporadic and di d not appear to be exclusively related to wet weather events. C. perfr ingens was identified as the most useful indicator of faecal pollution and was the only indicator significantly correlated to the presence o f pathogenic Giardia (r = 0.41, p < 0.05) and the opportunistic bacter ial genus Aeromonas (r = 0.39, p < 0.05). F-RNA bacteriophage was not significantly correlated with any of the pathogens examined. Copyright (C) 1996 Elsevier Science Ltd