As part of a long-term, peatland-scale sulfate addition experiment, the impact of varying sulfate deposition on bacterial community responses was assessed using 16S tag encoded pyrosequencing. In three separate areas of the peatland, sulfate manipulations included an eight year quadrupling of atmospheric sulfate deposition (experimental), a 3-year recovery to background deposition following 5 years of elevated deposition (recovery), and a control area. Peat concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, were measured, the production of which is attributable to a growing list of microorganisms, including many sulfate-reducing Deltaproteobacteria. The total bacterial and Deltaproteobacterial community structures in the experimental treatment differed significantly from those in the control and recovery treatments that were either indistinguishable or very similar to one another. Notably, the relatively rapid return (within three years) of bacterial community structure in the recovery treatment to a state similar to the control, demonstrates significant resilience of the peatland bacterial community to changes in atmospheric sulfate deposition. Changes in MeHg accumulation between sulfate treatments correlated with changes in the Deltaproteobacterial community, suggesting that sulfate may affect MeHg production through changes in the community structure of this group.
Bibliographical noteFunding Information:
The authors gratefully acknowledge Shu-Yi Shen and the Qiime community for technical genomics advice, Planck Huang who carried out chemical analyses, and helpful advice from Daniel Jones. Additional thanks go to Jeff Jeremiason, Ed Swain, Bruce Monson, Jim Almendinger and Brian Branfireun for their participation in the sulfate-addition experiments, and Randy Kolka, Deacon Kyllander, and Carrie Dorrance of the Northern Research Station for administrative and field assistance throughout the course of the project. This publication was based on work funded by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada to CPJM, and the U.S. EPA –Science To Achieve Results (STAR) Program, Grant R827630 , the Great Lakes Commission , Great Lakes Air Deposition Program, and the Minnesota Pollution Control Agency to DRE. These organizations had no role in the design, interpretation, or presentation of this project. The USDA Forest Service's Northern Research Station provided access to the study site as well as substantial in-kind support.
- Microbial ecology
- Sulfate reducing bacteria