Last August, 400,000 Toledo, Ohio residents lost access to drinkable water after efforts to control nutrient levels in Lake Erie broke down.
The amount of phosphorus and other nutrients, typically deposited by fertilizer runoff from farm fields, is used to measure the amount of bacterial buildup in bodies of water that can potentially turn toxic. However, it’s unknown what specifically causes the toxicity.
In light of these events, a team led by Gregory Dick, a marine microbiologist and associate professor of earth and environmental sciences, looked into what contributes to the formation of the potentially toxic cyanobacterial species, also known as blue-green algae.
According to a press release, the team was given a $250,000 dollar grant from the University’s Water Center for an 18-month project beginning in May 2014. Though data analysis is ongoing, the team will present information gathered over the past year at an international conference about cyanobacterial blooms next week. The conference will be held at Bowling Green State University in Ohio.
Though the runoff from farm fields has previously been identified as a contributing factor to the water shutdown, the team chose to focus on the internal factors in the water that could make buildup toxic.
Dick emphasized the collaborative aspect of the project and said there was a need to approach the study of toxicity in Lake Erie from many different perspectives.
“This research is a project that involves a large team of researchers from the University — there’s 11 of us from many different departments and schools at the University,” he said. “We’re also partnering with the NOAA Great Lakes Environmental Research Lab in Ann Arbor. An important aspect of that is this is a really complicated problem that involves a lot of different disciplines. To work on this problem, to understand this problem, I feel like we needed this large team to come at it from many different disciplinary perspectives.”
Dick’s team, in collaboration with another team led by aquatic geochemist Rose Cory, an assistant prof in earth and environmental sciences, hopes to discover which species of cyanobacteria are present in Lake Erie, which ones are toxic and what controls their toxicity.
Cory’s team has conducted tests on water for chemical substances that could play a role. One substance they identified is hydrogen peroxide.
Cory said toxin-producing cyanobacteria have a higher chance of surviving hydrogen peroxide takeover than the non-toxic blooms, upsetting the balance between the two and causing the toxic cyanobacteria to become prevalent.
“There’s really two main results (of the study),” she said. “One is concentration of hydrogen peroxide and just the amount that was there was pretty high compared to other natural waters like lakes or streams. Not all the time — not across the whole season — but concentrations of hydrogen peroxide were high, they peaked at times actually very much corresponding to when there was a peak in the microcystin-forming or toxin-forming cyanobacteria.”
Vincent Denef, assistant professor in the departments of ecology and evolutionary biology, said he and his part of the team approached the problem from the perspective of genomics, which focuses on DNA analysis.
“I had a technician that went out every week with the NOAA team to help with the sampling and then she’s been looking at genomics approaches,” Denef said. “We’re helped by the fact that human genome projects and the push for cheap human genomes has made genome sequencing extremely cheap for these tiny little bacteria.”
Both Dick and Cory highlighted the importance of using different disciplines to approach the problem, noting that they both work on different aspects of a similar issue.
“It’s a good collaboration because there’s this hypothesis about hydrogen peroxide and radicals influencing toxin-forming cyanobacteria that’s been around for a while, but people haven’t tested it,” Cory said. “This is because it requires a collaboration between Greg Dick’s group — people that are actually looking at the toxin-forming cyanobacteria — and someone like me who looks at the concentration of oxidants and radicals. Those require totally different knowledge and skill sets.”
Dick said he hopes the combined work will help to predict toxic cyanobacterial blooms in the future and prevent water shutdowns like the one in Toledo.
“The blooms themselves are a problem, but we think by better understanding which species are present — which strains of cyanobacteria are present — and what their biology is all about, we’ll be able to better understand when we have these toxics,” Dick said. “That could help us predict and understand these toxic blooms.”