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2017 | Stream Salinity

Ariel View of Streams

FACULTY SEED GRANT | Global Change Center

Microbial diversity response to a coal-mining induced salinity gradient in Appalachian headwater streams with possible implications for leaf litter breakdown.

  • Dr. Carl Zipper, Crop and Soil Environmental Sciences
  • Dr. Stephen Schoenholtz, Forest Resources and Environmental Conservation
  • Dr. Brian Badgley, Crop and Soil Environmental Sciences

Microbial communities, including bacteria and fungi, are the essential base of freshwater foodwebs and drive important ecosystem functions, such as leaf litter breakdown. However, these communities are often ignored in studies of ecosystem structure and function because quantifying their diversity has historically been difficult. Salinity acts as a primary determinant of microbial community structure over broad gradients that differentiate ecosystems at global scales, but little is known about how microbial communities vary over lower concentration gradients such as those represented by mining-influenced headwater streams. It is known, however that anthropogenic salinization alters both freshwater animal biodiversity and ecosystem functions. Here, we propose to expand on previous work that quantified microbial communities associated with leaf litter using next-generation sequencing in 24 Appalachian headwater streams across a coal-mining induced gradient of salinity. Despite exciting preliminary results indicating sensitivity of microbial communities to increased salinity, focused exploration of data-rich bacterial and fungal sequences is needed to broaden our understanding of microbial responses to low-level salinity and relationships to leaf litter breakdown rates.

This seed grant will allow us to accomplish four objectives: First, complete a detailed statistical analysis of bacterial and fungal data that has been generated but not analyzed. Use of multivariate and network analyses could uncover patterns in microbial community response to low-level salinity gradients in freshwater ecosystems that are undescribed and of broad potential significance. Second, combine these new analyses with our previous results to provide rare insight into effects of salinity on microbial and aquatic macroinvertebrate communities, which interact to carry out leaf litter breakdown functions in headwater streams. Third, publish novel findings that address microbial community sensitivity to salinization and influence on leaf litter decomposition rates. A current manuscript in preparation awaits the addition of results from microbial community analyses in order provide a unique look into relationships between ecosystem function and biodiversity (microbial + macroinvertebrate) along a salinity gradient. Fourth, present findings at the 2018 Society for Freshwater Science annual meeting in Detroit, MI. We feel the novelty and exposure of these results will create high likelihood of generating external grant funding because they address both basic and applied ecological questions related to biodiversity response to anthropogenic stressors, and to general biodiversity-ecosystem function relationships.