MICROBIAL STUDIES OF SEDIMENTS FROM PUBLIC CAVE LANDS: BASELINE DATA FOR MANAGEMENT

In the past few years, our research group has been investigating the relative diversity and abundance of microbial communities from sediments of two caves located on public lands. Over 100,000 people visit Timpanogos Cave National Monument (TC), UT, annually, and the trail portions have been significantly impacted. TC sediment samples were taken from both on-trail disturbed sites and off-trail ‘pristine’ sites for comparison. In contrast, Halliday’s Deep Cave (HD), in Great Basin National Park, NV, is only open for tours by permit, and has significantly less impact due to visitation. In this cave, sediment samples were taken from an area in the cave noted for abundant cave life. DNA was extracted from all samples, used in PCR to amplify a ~1500bp fragment of the 16S rDNA, cloned, and sequenced. Sequences were used in phylogenetic analyses to determine the evolutionary relationships of the clones. Currently, 84 bacterial clones from TC and 117 bacterial clones from HD have been sequenced. While clones belonging to similar microbial groups were retrieved from both caves, the relative abundances of the communities differ. Nine major taxonomic groups were found in disturbed TC sediments, dominated by Acidobacteria (39%), Gammaproteobacteria (24%), and Planctomycetes (18%). The only microbial sequences retrieved from the pristine sites in TC were related to Crenarcheota. Twelve taxonomic groups were retrieved from HD sediments, with the majority belonging to Betaproteobacteria (20%), Acidobacteria (17%), Alphaproteobacteria (16%), and Deltaproteobacteria (15%).

As a resource that is typically overlooked in managed caves, these microbial sediment studies can be applied to cave management decisions in several ways. In the case of HD, these baseline data can be used to asses the impact of visitation. For TC, which is already highly impacted, the same types of data can be used to monitor the affects of clean-up efforts. Finally, although a number of studies have investigated microbial communities in more unique cave environs (i.e. sulfur caves), there are very few studies that have documented the microbial diversity of more ‘typical’ oligotrophic cave environments. These studies will be useful as a foundation for identifying those microbes common in oligotrophic systems and those unique to cave environments.