Microbial Community Structure in St. Lawrence River Wetlands and Management of Mercury-Methylation

Session: 16. - How can Microbial Metagenomics Inform Management of Great Lakes Ecosystems?

Erin Eggleston, Middlebury College, [email protected]
Evie Brahmstedt, Clarkson University, [email protected]
Thomas Holsen, Dept. Civil & Environ. Eng., Clarkson University, [email protected]
MacKenzie E. Waller, St. Lawrence River Institute of Environmental Sciences, Cornwall, Ontario, [email protected]
Matthew Windle, St. Lawrence River Inst., [email protected]
Jeff Ridal, St. Lawrence River Institute, of Environmental Sciences, [email protected]
Michael Twiss, Clarkson University, Dept. of Biology & Great Rivers Center, [email protected]

Abstract

The International Joint Commission Plan 2014 guidelines for water level alteration at the Moses-Saunders power dam will likely mobilize hydric wetland soils and associated sediment into the nearshore of the St. Lawrence River.  Given the legacy deposition of Hg and sulfur, as well as abundant organic matter and phosphorus sequestered by Typha, we predict that mercury-methylating microbes (MMMs) will play a major role in Hg cycling, and mobilization, in this region. Four wetland types were compared (barrier beaches, drowned river mouths, protected embayments and open embayments) to assess the presence of MMMs. Amplicon sequencing (16S rRNA) was used to investigate overall microbial diversity in these hydric soils, as well as targeted analysis of three major clades of known and predicted MMMs (viz., sulfate-reducing Deltaproteobacteria, Firmicutes and methanogenic Archaea). We find that wetland type was not a good predictor of microbial diversity, and we detected MMMs from all three clades in all of the samples we tested.  Future studies are aimed at determining MMM activity in relation to redox status of hydric soils, which is related to water level management.

1. Keyword
microbiological studies

2. Keyword
methylmercury

3. Keyword
wetlands