A green, goopy algal bloom can bring summer fun at the cottage to a halt. Formed by an overgrowth of microbes called cyanobacteria, algal blooms are not just unsightly, they can be dangerous. They can release toxins that are harmful to people, pets, and wildlife.
But recent research out of the University of Waterloo suggests that cyanobacteria may have an enemy: viruses.
“We always hear about viruses in the context of human illnesses,” says Jozef Nissimov, one of the researchers and an assistant professor at the university. But viruses infect every form of life—that includes microorganisms such as cyanobacteria, he explains.
When a virus infects and kills a single-celled organism like a cyanobacteria, the cell will undergo a process called lysis. The cell ruptures and bursts, and everything that was once inside the organism will leak out into the environment. This knowledge prompted Nissimov and his team of researchers to wonder what would happen when a virus kills the microbes that cause toxic algal blooms.
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The team infected a strain of cyanobacteria in liquid with a virus and monitored the samples for toxin levels. Two days post-infection, the concentration of toxin in the surrounding liquid had increased four-fold.
The results showed that in a lab setting, viral infection can happen very quickly, killing the cyanobacteria and causing a spike in toxins. But as toxin levels soared, the water samples containing the cyanobacteria became clearer.
“When the cells die, you lose colouration,” says Nissimov. “The cells are not photosynthesizing anymore, so you don’t have the green colour that would be attributed to an active bloom. The water becomes clear—yet we can still detect these toxins at high levels.”
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The results are an intriguing look into the battles being waged on the microscopic level. And it begs the question: could viruses hold future secrets to controlling cottage algal blooms?
Nissimov says that because these results are from a lab setting, further work must be done to see how infections play out in natural ecosystems. “The next step will be finding out if viruses causing rapid release of toxins from dying cells happens in other species and other toxins.”
Unfortunately, this research shows that for cottagers, relying on water colour isn’t a reliable way to know if a lake is safe from algal blooms. Instead, Nissimov says to continue to look to your local public health and monitoring authorities for water quality updates.
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