Efforts to reduce the amount of phosphorus and other nutrients washing off farm fields and into Lake Erie shifted into overdrive after high levels of a bacterial toxin shut down the drinking water supply to more than 400,000 Toledo-area residents last August.
Nutrient levels help determine when and where rapid cyanobacterial buildups occur, as well as the size of those blooms. But what factors control their toxicity? The Great Lakes are home to dozens of common cyanobacterial species, but only a few are toxic troublemakers.
"We know what causes these blooms: It's nutrients from farm runoff. What we don't fully understand is what determines whether these cyanobacterial blooms are highly toxic or not," said University of Michigan marine microbiologist and oceanographer Gregory Dick, leader of a multidisciplinary project that applies state-of-the-art genomics and environmental chemistry techniques to the Lake Erie problem.
Dick said he hopes the study yields insights that can be incorporated into computer-based ecological models used to forecast cyanobacterial blooms.
"By applying innovative technologies to study these harmful algal blooms, we're opening new windows into what organisms are there and how those communities change over time," he said. "We're able to track specific organisms in a way that hasn't been possible before."
Dick's team was awarded a $250,000 grant from the U-M Water Center for an 18-month project that began May 1, 2014. Members of the team will present results from the 2014 field season this week during an international conference on cyanobacterial blooms at Bowling Green State University in Ohio. They will participate in a Monday evening poster session and a Wednesday workshop.
The U-M work relies heavily on the techniques of environmental genomics, which enable researchers to extract and sequence genetic material in water or soil samples and to piece together the genomes of the organisms present.
The project is expected to produce full DNA sequences for at least 50 Lake Erie microbes this year, Dick said. Thirteen genomes from laboratory-grown Great Lakes cyanobacterial strains have already been completed and will be used to aid in the interpretation of the environmental genomes.
"One of the unique elements of our study is that we tracked whole microbial communities in western Lake Erie for the entire season, so we'll be able to determine how the compositions change over time," Dick said. "No one else has looked at which microbial species are present at such a fine scale."
The U-M-led team includes 11 researchers from five U-M units and NOAA's Great Lakes Environmental Research Laboratory. The co-principal investigators are Dick, who is an associate professor in the Department of Earth and Environmental Sciences and in the Department of Ecology and Evolutionary Biology; Thomas Johengen of the Cooperative Institute for Limnology and Ecosystems Research; and Vincent Denef of the Department of Ecology and Evolutionary Biology.
In addition to U-M aquatic geochemist Rose Cory, other core team members include David Sherman of the Life Sciences Institute; Gary Fahnenstiel of the Water Center; Melissa Duhaime, George Kling and Tim James of the Department of Ecology and Evolutionary Biology; and Steven Ruberg and Davis of the NOAA lab. Findings from the studies will be submitted for publication in peer-reviewed scientific journals.
Read the full Michigan News press release