Studies on freshwater thermophilic amoebae in natural and man-made water bodies in the Rockhampton area

Free-living amoebae (FLA) are an assemblage of heterotrophic, eukaryotic organisms, which survive in a range of specialised and extreme environments worldwide. A few, namely Naegleria fowleri, pathogenic Acanthamoeba spp. and Balamuthia mandrillaris may occasionally become parasites of humans and produce life and sight-threatening diseases that are difficult to treat effectively. This thesis presents the findings of a 12-month survey of 3 natural and 3 man-made water-bodies in the Rockhampton area. It was undertaken to determine if these thermophilic FLA were present in readily recoverable quantities using the samplevolumes detailed in this study thereby reflecting high population densities which could pose a potential health hazard to humans using these water bodies recreationally." -- abstract. Free-living amoebae (FLA) are an assemblage of heterotrophic, eukaryotic organisms, which survive in a range of specialised and extreme environments worldwide. A few, namely Naegleriafowleri, pathogenic Acanthamoeba spp. and Balamuthia mandrillaris may occasionally become parasites of humans and produce life and sight-threatening diseases that are difficult to treat effectively.This thesis presents the findings of a 12-month survey of 3 natural and 3 manmade water-bodies in the Rockhampton area. It was undertaken to determine if these thermophilic FLA were present in readily recoverable quantities using the sample volumes detailed in this study thereby reflecting high population densities which could pose a potential health hazard to humans using these water bodies recreationally. Thennophilic FLA were recovered from all sites with the majority being isolated in the warmer months of spring and summer. In addition, culture dynamics and desiccation experiments were conducted to study the response of FLA to laboratory manipulation of parameters that included food supply and the effects of prolonged desiccation with the objective being to predict survivability of FLA populations in response to changing environmental conditions. Food supply experiments showed that N. fowleri would survive as dormant cysts after consuming a finite food supply. Desiccation experiments conducted at 22°C showed that all of the five species of thermophilic FLA would survive to 14 weeks. This thesis demonstrated that thermophilic FLA are a common component of the microbiota of freshwater bodies in Rockhampton's tropical environment.