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Stromatolites are the oldest evidence for life on Earth, but modern living examples are rare and predominantly occur in shallow marine or (hyper-) saline lacustrine environments, subject to exotic physico-chemical conditions. Here we report the discovery of living freshwater stromatolites in cool-temperate karstic wetlands in the Giblin River catchment of the UNESCO-listed Tasmanian Wilderness World Heritage Area, Australia. These stromatolites colonize the slopes of karstic spring mounds which create mildly alkaline (pH of 7.0-7.9) enclaves within an otherwise uniformly acidic organosol terrain. The freshwater emerging from the springs is Ca-HCO3 dominated and water temperatures show no evidence of geothermal heating. Using 16 S rRNA gene clone library analysis we revealed that the bacterial community is dominated by Cyanobacteria, Alphaproteobacteria and an unusually high proportion of Chloroflexi, followed by Armatimonadetes and Planctomycetes, and is therefore unique compared to other living examples. Macroinvertebrates are sparse and snails in particular are disadvantaged by the development of debilitating accumulations of carbonate on their shells, corroborating evidence that stromatolites flourish under conditions where predation by metazoans is suppressed. Our findings constitute a novel habitat for stromatolites because cool-temperate freshwater wetlands are not a conventional stromatolite niche, suggesting that stromatolites may be more common than previously thought.

A survey of small terrestrial mammals and bats was undertaken in rwo areas of southwestern Tasmania: around Melaleuca, in sedgeland, scrub and woodland communities, and at Clay tons in mixed forest. The density of bats was extremely low in comparison with populations in eastern Tasmania. The densities of Rattus lutreolusand Antechinus minimuswere greatest in sedgeland/scrub with a dense undergrowth. Pseudomys higginsi was only captured in mixed forest but is also present around Deny King's garden. Dasyurus viverrinuswas most abundant in young sedgeland. Cercartetus nanuswas present at both Clay tons and Melaleuca. No introduced rodents were trapped, but an outbreak of Rattus rattus had occurred previous to our study. No Mastacomys fuscuswere trapped but they have been recorded in a previous study. Fire has an important influence on the composition and structure of the vegetation which, in turn, influences the composition and density of the mammal community.

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