NSS Convention 2026

Three southern Appalachian caves, Daniel Boone Caverns (gated and locked with few visitors, Fort Blackmore, VA), Worley's Cave (a wild show cave, Bluff City, TN), and Linville Caverns (a developed show cave, Marion, NC) were assessed in a multiproxy analysis to determine if human visitation and development could influence cave mineralogy, inorganic geochemistry and microbial community assemblages. Sediments were analyzed using Illumina sequencing for microbial community structure, as well as a combination of X-ray diffraction, whole rock geochemistry, particle size distributions, and transmission electron microscopy (TEM) for mineral characterization.

Distinct geochemical and microbial signatures were found both within and between each cave. Biological manganese oxidation was present in all three caves, with significant differences in geochemistry across sites that contained Mn oxides vs. those that did not. Geochemistry and mineralogy of sediments primarily reflected the local bedrock rather than human-associated traffic and detritus. PCA plots using whole rock geochemistry (cross-referenced with X-ray diffraction data) indicate that sediment variability between caves was due to the amount of clay minerals vs. detrital feldspars and quartz, as well as the amount of detrital heavy minerals vs. Mn oxidation and phosphate.

Sediment-hosted microbial communities from the developed show cave, Linville Caverns contained more Bacteroidota (a phylum associated both with high molecular weight carbon and humans) than the other two caves, while Daniel Boone caverns, a relatively pristine cave, contained more Thermoplasmatota, Chloroflexota, and Nitrospirota (oligotrophic phyla), corroborating studies demonstrating that Bacteroidota are positively correlated and Nitrospirota are negatively correlated with anthropogenic and nutrient input.