The composition and dynamics of fungal communities associated with harmful algal blooms
Recent harmful algal blooms (HABs) in the Laurentian Great Lakes have been attributed in large part to a combination of nutrient inputs and climate. However, other factors may also influence the magnitude of HABs but have received little attention. For instance, fungal pathogens can strongly influence phytoplankton populations and are known to infect bloom-forming species, but the role of fungi in Great Lakes HABs is mostly unknown. For this project, we took steps towards better understanding the role of fungi in Great Lakes blooms by characterizing the composition and dynamics of the fungal community during the 2014 Lake Erie bloom. We also examined the fungal community in Saginaw Bay in Lake Huron and six inland lakes to compare communities across Lakes that differ in bloom magnitude and other characteristics. Samples were collected across the growing season and the fungal community characterized using next generation (PacBio RS II) sequencing.
Several major fungal groups were broadly represented in samples, especially members of Chytridiomycota and Cryptomycota. Represented fungal groups are known to include parasites of bloom-forming species, including the dominant cyanobacterium in Lake Erie blooms, Microcystis aeruginosa. Sites within and across lakes that varied in bloom magnitude also differed in the composition of the fungal community. Furthermore, notable changes occurred in the fungal community over time from the initiation of the bloom to its peak and subsequent decline. Our findings thus greatly advance our understanding of an understudied but potentially important component of the Lake Erie ecosystem.