Genomic Characterization of Toxic Cyanobacterial Community Dynamics in Missisquoi Bay, Quebec

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

Charles Greer, National Research Council Canada, [email protected]
Nathalie Fortin, National Research Council Canada, [email protected]
Nicolas Tromas, Université de Montréal, [email protected]
B. Shapiro, Université de Montréal, [email protected]

Abstract

We have been using a genomics-based approach to monitor and characterize cyanobacterial blooms in the Quebec portion of Missisquoi Bay, Lake Champlain since 2006.  Sequencing technologies are powerful approaches to survey microbial diversity and investigate cyanobacterial population dynamics. We have observed that the extensive flood event during the spring of 2011 in Lake Champlain was concomitant with a dramatic reduction of the genus Microcystis for the first time since 2007. High-throughput sequencing of 16S rRNA gene amplicons showed that shifts in dominance occurred primarily between the genera Microcystis and Dolichospermum. Drastic shifts in populations favouring Microcystis appeared to be associated with intense rainfall events and the subsequent spike of nutrients such as phosphorus and dissolved nitrogen. A significant correlation between rainfall and the opportunistic pathogen E. coli was also observed in our tributary stations. During intense rainfall episodes, nutrients typically originate from sewage overflow, surface runoff and tile drain effluents. The resulting high concentrations and types of nutrients can promote the growth of toxin-producing cyanobacteria. Our results suggest that wastewater overflows should be controlled and that manure and fertilizer application prior to intense rainfall or prolonged periods of rain should be avoided in the spring and throughout the year.

1. Keyword
genetics

2. Keyword
biodiversity

3. Keyword
microbiological studies

4. Additional Keyword
Microcystis

5. Additional Keyword
Community dynamics

6. Additional Keyword
Toxic cyanobacteria