Forecasting Microcystin Concentrations in Western Lake Erie

Session: Watershed and Lake Science Informing Management (2)

Justin Chaffin, Stone Laboratory, Ohio State University, chaffin.46@osu.edu
John Bratton, LimnoTech, jbratton@limno.com
Thomas Bridgeman, Dept. of Environmental Sciences, University of Toledo, thomas.bridgeman@utoledo.edu
Timothy Davis, Bowling Green State University, timdavi@bgsu.edu
Kevin Meyer, University of Michigan, kevmey@umich.edu
Ed Verhamme, LimnoTech, everhamme@limno.com
Judy Westrick, Wayne State University, westrick@chem.wayne.edu
Pengfei Xue, Michigan Tech, pexue@mtu.edu

Abstract

In recent years, a Lake Erie cyanobacterial bloom forecast has been issued in early July based on the spring phosphorus load. Although bloom size and location can be reasonably well forecasted, questions remain about the controls and predictability of microcystins (MC) concentrations. One complexity in field studies has been the coexistence of toxic and non-toxic strains of Microcystis. The factors influencing the dynamics of toxic and non-toxic strains within blooms are only beginning to be understood, but they may be at the point where reasonable predictions of changes in MC concentrations could be possible. While phosphorus has a clear role in bloom dynamics, nitrogen may also be important in the occurrence and biomass of cyanobacteria and the toxicity within the blooms. Other factors, such as light intensity and temperature, may also interact with nitrogen to impact MC production. This presentation will present (1) historical (since 2014) MC and cyanobacterial biomass correlations from 4758 samples collected between June and October in the western basin, (2) numerical models of ecological and physical processes to develop hindcasting, nowcasting, and forecasting capabilities, and (3) laboratory experiments that quantified MC production rates under ambient and elevated nutrient concentrations.