Ecological impacts of human activities on microbial community composition and microbial-mediated activities in Hailstone National Wildlife Refuge, an alkaline, hypersaline, and selenate-contaminated site in South-Central Montana

2014 to 2016

Hailstone National Wildlife Refuge (NWR) is a ~ 2,000-acre area located in northern Stillwater County. A combination of natural factors such as saline seeps and selenium-rich bedrock, and anthropogenic causes such as the loss of native grasslands, summer-fallow agricultural practices, and the presence of a dam (now dismantled), have resulted in salt concentrations as high as 88,900 μS/cm (seawater is about 55,000 μS/cm) and selenate concentrations as high as ~3,000 μg/L in places (chronic water standard for selenium is 5 μg/L). These conditions have been detrimental to vegetation and wildlife, and the lake bed to former Hailstone Lake is now a barren salt-encrusted basin. Although extreme, the geochemistry of Hailstone NWR is representative of other sites in Montana and the Western United States.

Our aim is to characterize the microbial communities and activities taking place in Hailstone NWR with the goals of aiding reclamation and bioremediation activities, and to understand the human impact on microbial communities in this site.  We have taken a combination of sequencing-based and culture-based approaches for this purpose.  High throughput 16S rDNA sequencing has revealed a diverse microbial community dominated by anaerobes of the phyla Bacteroidetes, Firmicutes, and by a diverse community of sulfate-reducing Proteobacteria. We have obtained pure cultures of both aerobic and anaerobic selenate reducers from the bacterial genera Pseudomonas, Halomonas and Bacillus.



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