Presentation: Quagga mussel food choice at the HAB buffet by Anna Boegehold with the Cooperative Institute for Great Lakes Research and Vincent Denef with the University of Michigan

Description: Dreissenid mussels (quagga and zebra mussels) are powerful ecosystem engineers in the Laurentian Great Lakes, causing short and long term changes to phytoplankton such as algae and cyanobacteria. In western Lake Erie, invasive mussels have been implicated in promoting harmful algal blooms (HABs) in part by selectively feeding on green algae and diatoms while rejecting cyanobacteria like Microcystis aeruginosa. Multiple genetically distinct strains of M. aeruginosa can be found in a single HAB event, and the ecological significance of a bloom can be dependent on which strains are present. In order to gain insight into dreissenid feeding behavior during a HAB, we presented mussels with a choice between a preferred green algae and 7 strains of M. aeruginosa collected and isolated from western Lake Erie. In our study, quagga mussels consumed 100% of the green algae and did not eat the cyanobacteria, however there was some variability in mussel feeding behavior dependent on the M. aeruginosa strain they were exposed to. These experiments can give us an idea of 1) are quagga mussels in Lake Erie eating any of the M. aeruginosa strains when a better food source (i.e. green algae) is available? 2) What factors contribute to this choice? 3) How do these trophic dynamics between primary producers and primary consumers in the lab translate to bloom succession in western Lake Erie and beyond?