Discovery May Yield a Natural Way to Control Toxic Algae

Fri, 17, March, 2023 by Food from Thought

A tiny crustacean may hold the key to preventing toxic effects from outbreaks of algae in the Great Lakes and other freshwater bodies, according to University of Guelph biologists.

Blooms of cyanobacteria (blue-green algae) can taint drinking water and harm fish and wildlife. The blooms are caused mainly by excessive nutrients from fertilizer runoff from farm fields and warm water temperatures.

“We’re looking to develop basically a biocontrol agent to mediate or suppress cyanobacteria outbreaks,” says Dr. John Fryxell, a professor in the Department of Integrative Biology within the College of Biological Science. They may have found one in Daphnia, a minuscule crustacean commonly called a water flea.

Says Fryxell, “If we can encourage Daphnia as a biocontrol agent, it might be a beneficial way of naturally responding to these outbreaks.”

His team included Dr. Seth Rudman, now a faculty member at Washington State University (WSU), and Dr. Rene Shahmohamadloo, now a Natural Sciences and Engineering Research Council and Liber Ero post-doctoral researcher with WSU and the University of Guelph.

This Food from Thought project aims to address a serious environmental and human health threat. For example, in summer 2014, the drinking water system in Toledo, Ohio, had to shut down for two days after a cyanobacteria outbreak.

The research

The U of G team worked with 20 clones of Daphnia magna, whose adults grow no bigger than five millimetres. The researchers studied the organism’s sensitivity to both healthy green algae and cyanobacteria in different concentrations. They recorded the water flea’s lifespan and growth and reproduction rates among other parameters. Daphnia can live for weeks in warm water and for several months in colder water.

“The results showed that there’s quite a lot of variation in the sensitivities between clones,” says Fryxell.

The researchers cultured Daphnia in Lake Erie water temperatures to see how they reacted over a typical growing season. Experiments with groups of single clones and with mixtures of clones took place at the Hagen Aqualab on the University of Guelph campus. The team is now analyzing the results.

Next steps

“We’re interested in the interplay of differing concentrations of cyanobacteria and competition within the Daphnia population,” Fryxell says.

To study that interplay, the team is developing a technique using DNA markers to distinguish variants of Daphnia. Using this DNA assay, the team hopes to better evaluate how well different strains of Daphnia cope with the cyanobacteria throughout the growing season.

“We’re entering into the proof-of-concept phase,” says Fryxell. “What makes this project different from other biocontrol projects is that these are strains within a species – not different species.”

He says the team hopes to encourage existing genotypes that do the best job of suppressing cyanobacteria. They also hope to learn why cyanobacteria harm some organisms but not others.

This is discovery science, says Fryxell, meaning that developing biocontrols for real-world conditions can take years or decades.

“We’re doing this to find out if there’s a potential here – which we think there is – and we’re determining what the constraints are.”

This story is a part of the 2021-22 Food from Thought Annual Impact Report