Mycoplankton response to lake trophic state and phytoplankton community composition in Canadian lakes

Aquatic fungi are ubiquitous and play essential roles in organic matter decomposition and nutrient cycling in freshwater systems. In plankton, however, they have been largely overlooked, particularly in lakes. Hence, there is a need to evaluate their diversity and community composition on a large spatial scale. Using 18S rRNA gene amplicons from surface water of 369 Canadian lakes sampled across several biomes as part of the NSERC Lake Pulse Network, we examined the diversity and community composition of mycoplankton along a trophic gradient, assessing their potential as indicator species. The dominant fungal group in taxa and sequence numbers belonged to Chytridiomycota, followed by Dikarya. The diversity of fungi declined with increasing total phosphorus, with the greatest difference seen in oligotrophic vs. hypereutrophic lakes. Similarly, fungal community composition varied greatly between oligotrophic and hypereutrophic lakes although only a small proportional (~4-6%) was explained by the change in trophic status. Ions, pH, and land use were identified as drivers of fungal diversity and community composition. Using Co-Inertia analyses, fungal communities had higher correlations with eukaryotic phytoplankton rather than environmental variables, which indicated the importance of parasites in mycoplankton. This study is the first to analyze the diversity and community composition of mycoplankton in lakes on a large spatial scale revealing a high potential of mycoplankton as indicator of phytoplankton composition and other environmental variables.

Primary Presenter: Joanna Gauthier, University of Ottawa (gauthier.joanna@gmail.com)

Authors:

Joanna Gauthier, University of Ottawa  (joanna.gauthier@uottawa.ca)

Frances Pick, University of Ottawa  (Frances.Pick@uottawa.ca)

Rebecca Garner, University Concordia  (rebecca.garner@mail.concordia.ca)

Hans-Peter Grossart, Leibniz Institute for Freshwater Ecology and Inland Fisheries, IGB  (hanspeter.grossart@igb-berlin.de)

David Walsh, Concordia University  (david.walsh@concordia.ca)