Mercury methylation in Sphagnum moss mats and its association with sulfate-reducing bacteria in an acidic Adirondack forest lake wetland

Ri Qing Yu, Isaac Adatto, Mario R. Montesdeoca, Charles T Driscoll, Mark E. Hines, Tamar Barkay

Research output: Contribution to journalArticle

29 Scopus citations


Processes leading to the bioaccumulation of methylmercury (MeHg) in northern wetlands are largely unknown. We have studied various ecological niches within a remote, acidic forested lake ecosystem in the southwestern Adirondacks, NY, to discover that mats comprised of Sphagnum moss were a hot spot for mercury (Hg) and MeHg accumulation (190.5 and 18.6 ng g-1 dw, respectively). Furthermore, significantly higher potential methylation rates were measured in Sphagnum mats as compared with other sites within Sunday Lake's ecosystem. Although MPN estimates showed a low biomass of sulfate-reducing bacteria (SRB), 2.8 × 104 cells mL-1 in mat samples, evidence consisting of (1) a twofold stimulation of potential methylation by the addition of sulfate, (2) a significant decrease in Hg methylation in the presence of the sulfate reduction inhibitor molybdate, and (3) presence of dsrAB-like genes in mat DNA extracts, suggested that SRB were involved in Hg methylation. Sequencing of dsrB genes indicated that novel SRB, incomplete oxidizers including Desulfobulbus spp. and Desulfovibrio spp., and syntrophs dominated the sulfate-reducing guild in the Sphagnum moss mat. Sphagnum, a bryophyte dominating boreal peatlands, and its associated microbial communities appear to play an important role in the production and accumulation of MeHg in high-latitude ecosystems.

Original languageEnglish (US)
Pages (from-to)655-668
Number of pages14
JournalFEMS Microbiology Ecology
Issue number3
StatePublished - Dec 2010



  • Acidic Adirondack lake wetland
  • Hg methylation
  • Sphagnum moss mats
  • Sulfate-reducing bacteria

ASJC Scopus subject areas

  • Ecology
  • Applied Microbiology and Biotechnology
  • Microbiology

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