COLIFORM BACTERIA IN STREAMBED SEDIMENTS IN A SUBTROPICAL RAIN-FORESTCONSERVATION RESERVE

Mean concentrations of coliform bacteria in streambed sediments in a s ubtropical rainforest conservation reserve in Queensland, Australia, u ndisturbed except by tourists walking, camping and swimming, were appr oximately 0.5 x 10(6) cfu/100 mi during the dry season and 1.2 x 10(6) cfu/100 mi during the wet season, with the difference significant at p < 0.001. In general, total coliform concentrations in sediments were not significantly correlated with sampling site, rainfall, streamflow or visitor numbers on the sampling date. Concentrations in sediment we re approximately 1000 times higher than in the overlying water column (95% c.i. 750-1500x). Eighteen individual bacterial species in the Ent erobacteriaceae and Vibrionaceae were identified, including species of Klebsiella, Enterobacter,, Escherichia, Acinetobacter, Citrobacter, S erratia, Providencia, Morganella, Plesiomonas and Aeromonas. Two of th ese, Plesiomonas shigelloides and Aeromonas hydrophila, are pathogenic to humans. P, shigelloides is a common cause of severe human diarrhoe a in Asia. This is the first time it has been identified from natural surface waters in Australia. (C) 1998 Elsevier Science Ltd. All rights reserved.