Master’s student Chelsea Salter of the Great Lakes Institute for Environmental Research (GLIER) is investigating why and how bacteria are able to naturally break down toxins in the sandy trenches of Pelee Island’s shore before those toxins can contaminate the residents’ drinking water.

Salter (BSc 2020) was awarded a graduate research fellowship with the Cooperative Institution for Great Lake Research (CIGLR) at the University of Michigan to pursue the project.

Harmful algal blooms are collections of cyanobacteria which produce toxic secondary metabolites and release them into water bodies, creating potentially significant human health risks in freshwater lakes around the world. Of the cyanobacterial toxins that exist, microcystins are the most common and most toxic.

“The history of cyanobacterial blooms in Lake Erie came to a climax in the summer of 2014 when a toxic algal bloom released high concentrations of microcystins into the city of Toledo, Ohio’s municipal water inlet, resulting in a three-day ‘do not drink’ advisory,” says Salter.

“During that same time period, Pelee Island, though also situated in the western basin of Lake Erie like Toledo, showed no toxic contamination in their drinking water treatment facilities.”

Pelee Island’s municipal water supply and residential drinking wells both gather their water directly from the lake that has passed through sand-filled trenches.

“Basically, the trenches of sand are teeming with microbes and it appears that these bacteria are degrading the toxins before they reach the water supply,” she says.

“We are mimicking Pelee’s natural microbe landscape in the lab by filling flow-through columns with lake water and beach sand collected from the island in the summer of 2020 with the aim of studying how microbe communities are able to degrade the toxins, and which species are specifically responsible.”

Salter’s plan is to analyze the microbial community to detect which species are active during exposure to microcystins. Even when boosting the toxic concentrations to levels higher than what would normally be present during a bloom event, the team has seen the toxins get broken down in less than a day.

“I’m very excited to work on this project and contribute to tangible, safe solutions to environmental issues,” says Salter. “It is why I went into science.”

For her fellowship, Salter receives a $18,000 U.S. one-year scholarship and guidance from mentors on both sides of the border. Chris Weisener, a professor with the School of the Environment and GLIER researcher, is the lead mentor.

“The potential outcomes of Chelsea’s work will provide a more detailed understanding of the bacterial community diversity and identify specific metabolic pathways involved in the degradation processes of the toxin,” says Dr. Weisener.

“Down the road, this information can be developed for potential industrial applications for biological freshwater treatment and other biotechnological breakthroughs.”

Judy Westrick, director of the Lumigen Instrument Center at Wayne State University, lends her expertise in cyanotoxins and harmful algal blooms, her analytical methodologies, and specialized instrumentation.

“Without Judy’s expertise and her mass spectrometer, there is no way I could get the same detail of information, which is crucial for my process,” Salter says.

Former GLIER researcher Subba Rao Chaganti is currently an assistant research scientist at the University of Michigan and will be her CIGLR mentor.

“Chelsea's project has no borders,” says Dr. Chaganti. “People living across the Great Lakes can benefit from the results generated from this project, as it deals with the removal from drinking water of the microcystin toxin released by harmful algal blooms.”

Salter’s initial results were published in Science Direct’s journal, Chemosphere, “Investigating the Microbial Dynamics of Microcystin-LR Degradation in Lake Erie Sand,” in February 2020.

—Sara Elliott