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| Photo Credit: Lara Jansen. |
Researchers at McGill University have identified bacteria that can indicate whether a blue-green algae (cyanobacteria) bloom is likely to be toxic, offering a potential water-safety early warning system. Blooms are becoming more frequent due to climate change, according to previous McGill research. They can produce various contaminants, known as cyanotoxins, that pose serious health risks to humans, pets and wildlife.
The study was led by Lara Jansen in Professor Jesse Shapiro’s lab, in the Department of Microbiology and Immunology. It showed that bacterioplankton populations shift in proportion to the broader bacterial community during a bloom. Jansen conducted the research at McGill as a PhD student, while on exchange from Portland State University.
Some of the bacterioplankton she identified – including some related to those known to break down cyanotoxins – were consistently more abundant in toxic blooms, suggesting that shifts in these bacterial populations may indicate a need for further testing to determine whether the water in a lake has become hazardous.
A consistent, cost-effective method
The team collected water samples and analyzed DNA extracted from the aquatic bacterial community (bacterioplankton), comparing them to a database of DNA sequences to identify the types of bacteria present in the lake.
“Sampling bacteria is a relatively cost-effective measure, because DNA sequencing costs have come down a lot,” Jansen said. “It’s useful to find tools that can capture data cheaply, because these sites are often far from major urban centres.”
The researchers also tested for microcystin, the most common cyanotoxin in these lakes, and found that the bacteria appeared during the same timeframe. This finding confirmed the bacteria’s presence as a probable harbinger of toxins.
Consistent results across ecosystems
While previous studies focused on lakes that were similar to each other, this research compared two ecologically distinct lakes in the Cascade Mountains with different nutrient levels. The results showed that bacterial communities reflect bloom toxicity across ecosystems.
“These mountain lakes are popular for recreation and exist at the headwaters of major drinking water sources,” Jansen explained. “Cyanotoxins don’t always degrade quickly, so there’s potential for downstream migration.”
Current toxin testing methods are expensive and must be repeated throughout a bloom period. Jansen’s approach offers a more efficient alternative that could indicate when the other methods are needed
Improving public safety through better communication
Even with testing, Jansen noted that public health messaging around harmful algal blooms remains a challenge.
“There can be advisories in place, but people are still boating – and water aerosolization can carry toxins into the air,” she said. “I had to encourage people myself not to go in the water. Agencies are doing their best, but it’s hard with limited personnel.”
Understanding how bacteria respond to toxic blooms could help improve risk communication and guide more timely interventions, Jansen said.
Authors: Lara Jansen, Nicolas Tromas, Angela Strecker, and Jesse Shapiro
Source/Credit: McGill University
Reference Number: mcb110325_01