1. The secondary salinisation of wetlands is a global problem that poses a great threat to most freshwater biodiversity, including amphibians. We examined tadpole diversity in relation to wetland conductivity (our proxy for salinity) in wetlands in south-eastern Australia to better understand (i) how salinity and amphibian diversity interact and (ii) the threat posed by secondary salinisation. 2. Six tadpole species were trapped in 56 wetlands that reflected a typical salinity gradient for the study region. We developed Bayesian models to examine the relationships between conductivity and both the probability of species occupancy and expected number of species with the imperfect detection probability of species accounted for in the models. 3. The probability of occupancy for all species and expected species number was negatively associated with wetland conductivity. Our results predict that conductivity should not limit tadpole presence below about 3000 lS cm )1 at 25°C (approximately 6% seawater) in the region, but will largely exclude amphibian larvae beyond about 6000 lS cm )1 at 25°C (approximately 12% seawater). 4. We also detected subtle among-species differences in salinity tolerance. The results reported here show that tadpoles in the study region are likely to be negatively affected by projected future increases in salinisation.

Factors affecting the foraging of mobile native fauna in highly fragmented urban landscapes have seldom been quantified at large spatial scales. We investigated factors affecting foraging by Grey-headed Flyingfoxes ( Pteropus poliocephalus ; 'flying-foxes') in the greater Melbourne metropolitan area. Flying-foxes established a continuously occupied colony site in the Royal Botanic Gardens Melbourne in 1986, and the size of the colony has subsequently increased greatly. We used a stratified-random sampling design to examine the importance of six variables on the detection of foraging flying-foxes: (i) distance from the colony site (0-10, 10-20 and 20-30 km); (ii) distance from the Yarra River (0-5 and 5-20 km); (iii) the relative tree density of the municipality; (iv) whether the site was a park or street; (v) whether there was a relatively high or low density of trees at the site; and (vi) whether food was or was not detected at the site. We surveyed 240 sites within a 30-km radius of the colony site for foraging flying-foxes in both May and October 2002. The probability of detecting a foraging flying-fox declined with increasing distance from the colony site, but increased with increasing tree cover, and was higher for parks compared with streets and when food was present. Flying-foxes were observed foraging in a number of plant genera that have no species that naturally occur in the Melbourne area. Flying-foxes in Melbourne thus forage on planted resources that are widely distributed within a fragmented landscape, and are an example of a positive response by a native species to the process of urbanization.

Because of its efficacy in inactivating waterborne protozoan cysts and oocysts, ozone is frequently used for disinfection of drinking water. The effect of ozone on cysts of Giardia lamblia was investigated in gerbils (Meriones unguiculatus), using an infectivity assay by scanning electron microscopy, immunoblotting, and flow cytometry. Cysts recovered from experimentally infected gerbils were exposed to an initial ozone concentration of 1.5 mg/L for 0, 30, 60, and 120 sec. This treatment resulted in a dose-dependent reduction in cysts concentration, loss of infectivity in gerbils, and profound structural modifications to the cyst wall. Exposure for 60 sec or longer resulted in extensive protein degradation and in the disappearance of a cyst wall and a trophozoite antigen.

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Athalassic wetlands play a pivotal role in sediment and nutrient cycling and retention at the catchment level and are important ecosystems for local and regional biodiversity. Yet, the management of wetlands outside of riverine floodplains (non-riverine wetlands) is difficult, as there is limited understanding of these water bodies and of the processes that threaten them, like secondary salinisation. Accordingly, we describe the patterns of variation in wetland salinity and water chemistry across a regional landscape that is threatened by secondary salinisation. Spatial analyses indicated the distribution of the study wetlands was non-random and there was considerable positive spatial auto-correlation in water chemistry among wetlands-indicating a lack of independence. We detected massive variation in water chemistry among wetlands compared to minimal within-wetland variation and conductivity accounted for most of the among-wetland variation confirming its prominence in non-riverine wetland water chemistry. Wetland salinities were classified by their chemical evaporative pathway and we found a number of wetlands that may have become secondary salinised. The results reported here support the notion that the study, conservation and management of non-riverine wetlands should include assessments made at multiple spatial scales from individual waterbodies through to catchments. This is important because wetlands may not be independent units, but components of larger systems. However, we also note that the use of individual wetlands as units of replication may be problematic under some circumstances. We also argue that the identification of secondarily salinised wetlands will often require a multiple lines of evidence approach.