We are investigating the links between environmental variables and harmful algal bloom (HAB) toxins in Lake Erie to better understand the process of toxin development and to forecast HAB toxicity. We are also conducting field and lab experiments to close knowledge gaps on the influence of nitrogen, light, and temperature on microcystins, the HAB toxins that contaminated drinking water in Toledo, Ohio, in 2014, resulting in a temporary drinking water ban.

Why We Care
When fresh water HAB toxins contaminate a supply of drinking water, especially one associated with a municipal drinking water system, they have the potential to affect the health of many people in a single event. Such an event occurred in Toledo, Ohio, in 2014 when elevated levels of microcystins led to a drinking water ban that affected almost 500,000 people who depend on Lake Erie as their water supply.

What We Are Doing
Lake Erie is relatively shallow and has a large watershed to surface area ratio, which makes it susceptible to HABs resulting from excess nutrient loading. Although HAB size and location can be well monitored and forecasted at this point for Lake Erie, fundamental questions remain about the controls and predictability of toxin production in blooms.

One difficulty in past field studies has been the coexistence of toxic and non-toxic strains of the same species of cyanobacteria, which are morphologically indistinguishable. Now, scientists understand the factors influencing the dynamics of toxic and non-toxic strains, and reasonable predictions of changes in toxicity are possible. While phosphorus has a clear role in HAB 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 HAB toxin production.

 Our study has three components:

1. Examination of historical data to look for correlations between changes in environmental variables and changes in HAB toxin concentrations.
2. Incorporation of historical data results in numerical models of ecological and physical processes to develop hindcasting, nowcasting, and forecasting capabilities.
3. Field and laboratory experiments to better focus knowledge gaps identified, including the influence of nitrogen, light, temperature, and other factors on the production and decay of HAB toxins.

Dr. Justin Chaffin of the F. T. Stone laboratory at The Ohio State University leads this project along with co-partners at LimnoTech (Inc.), Michigan Technological University, the University of Toledo, and Wayne State University. The project is funded through the NCCOS Ecology and Oceanography of HABs (ECOHAB) Program.

Benefits of Our Work
Our project will yield a suite of presentations, publications, and tools to inform stakeholder and scientific audiences of the advances made in understanding HAB toxicity. One of these products will be specific technical guidance to NOAA’s Center for Operational Oceanographic Products and Services and drinking water utilities describing how to incorporate new information and improved forecasting capabilities in their operational systems.