Bone-appétit! The influence of microrganisms on bone preservation in caves at Naracoorte, South Australia

Abstract

The bacteria and fungi introduced into subterranean environments are implicated as causal organisms for destruction of Palaeolithic art and vertebrate fossils. Taphonomy studies characterise modifications resulting from acidic and enzymatic exudates of microbial metabolisms, as fungal tunnelling, and bacterial pitting. However, few studies are privy to the natural biostratinomic history of the animal’s decomposition, or the environmental variables and microbes influencing bone bioerosion. Hypotheses include early decomposition, soil burial, excessive nutrients and introduced diversity from tourism as catalysts of microbial erosion. Using modern in-situ bones from a decomposition study by Reed (2009) conducted within private caves in Naracoorte, South Australia, this study provides preliminary data on the associations between environment and the types of bioerosion that compromise bone preservation. Using Scanning Electron Microscopy (SEM) for characterising modifications, genetic profiling of microbial communities in caves and environmental cave assessments indicates that the observed diverse microbial communities are not conducive to bioerosion of vertebrate fossils in Naracoorte Caves. Moreover, less diverse fungal communities within closed, oligotrophic caves appear to have greater degradative abilities during prolonged extraction of organic minerals. Naracoorte Caves National Park captures the imaginations of the public and scientists for their invaluable retrospect on native faunal communities throughout the Pleistocene. Taphonomic analyses of the fossils recovered from NCNP are used for research that enables investigation on ecological changes, geological histories, and faunal extinction by providing data models used in environmental research and management. Thus, taphonomic investigation of microbial destruction of vertebrate bone is a useful in understanding the diagenetic histories of important fossil assemblages.