How blue-green algae blooms are threatening the Great Lakes
Great Lakes Institute of Environmental Research confirms presence of cyanobacteria in Lake St. Clair
Freshwater blue-green algae blooms are a global phenomenon that can affect humans, pets, the environment and the economy. And as weather patterns shift, the blooms — which prefer warm, nutrient-rich water — are appearing in areas where they wouldn't commonly occur, according to one researcher.
Though blooms typically show up in shallow bodies of water with temperatures above 20 C in areas of higher agricultural activity, blooms in colder and more nutrient-poor lakes have been observed more frequently than previously expected, including Lake Superior and Lake Huron, said Mike McKay, director of the University of Windsor's Great Lakes Institute of Environmental Research (GLIER).
The issue can't only be chalked up to rising temperatures, however.
"We've seen a higher frequency of extreme rainfall event[s]. This causes nutrients tied up in the soil surrounding the lake to be washed into the lake, and we've seen blooms in Lake Superior off the coast of Thunder Bay over the past decade," said McKay.
"This combination of nutrient loading, whether from farming or an extreme weather event, combined with warming can cause blooms."
Locations such as Lake St. Clair on the Michigan border and the western shore of Lake Erie in Ohio are common recipients of the phenomenon, given higher surface temperatures and high nutrient input.
Earlier this week, the Windsor-Essex County Health Unit issued a warning of an apparent blue-green algae bloom in Lake St. Clair, located between Lake Erie and Lake Huron in southwestern Ontario.
After checking satellite readings with both the U.S.-based National Oceanic Atmospheric Administration (NOAA) and Environment Climate Change Canada, McKay confirmed there was a layer near the shore that showed signs of cyanobacteria, the microorganisms otherwise known as blue-green algae.
McKay describes the blooms as "unsightly," but also producers of neurotoxins and hepatotoxins that affect the neurological system and liver if ingested.
Water researchers take trip to China
Along with a group of 24 other scientists from 12 different countries, McKay recently returned from China, representing his role with GLIER. It's an international relationship that has been established over the past 15 years, where strategies and discussions have attempted to combat a shared problem: freshwater algal blooms.
"We find them around the world, it's not just a phenomenon we find in the Great Lakes of North America," said McKay.
McKay says that China has a similar equivalent, the Yunnan Plateau Lakes, located in the country's southwestern quadrant. According to McKay, algae act like microscopic plants, present universally but not always in bloom.
"Think of what you need to grow a plant. Sunlight, carbon dioxide, water and nutrients, [or] fertilizer. So all that remains is the nutrients and we're providing that mainly through agricultural activity."
"Some algae are good. They end up being eaten by other plankton and eventually incorporated into the food web. These [blue-green algae] are different. They are buoyant and form scum on the surface of the water. They also frequently form toxins which can be harmful to humans."
The government of Ontario advises that when blue-green algae is spotted "assume the toxins are present."
"I'm not concerned about [drinking water] because our municipal utilities are very good at removing these contaminants. Most people wouldn't want to swim in green water, either. But there are recognized risks that vary with exposure," McKay said.
Perhaps more of a concern for groups such as GLIER is the environmental effect. When a blue-green algal bloom dies, the decomposed biomass causes "dead zones" in the lake, lowering oxygen levels. McKay says that pets are also drawn to the leftover "dried mats" from the dead organisms, which still contain toxins and could lead to death if consumed.
Currently, mitigation efforts are dependent on the size of the affected lake. According to McKay, smaller lakes can have blooms treated with interventions such as a hydrogen peroxide, which can kill the bacteria.
For larger lakes, such as Lake St. Clair or Lake Erie, the treatment is ineffective.
"[Instead], we have to work more with the farming community to identify best management practices so that less fertilizer is leaching into the lakes. Really for something like Lake Erie, we need to reduce nutrient inputs."
As discussions continue, McKay also hopes to highlight the possible socioeconomic implications, as well as research into the potential threats that come with aerosols for people living near areas of blooms.
"[Increased blooms could] result in reduced recreational opportunities for fishers, which leads to reduced property values and reduced tourism. And what's emerging now is asking if there is higher exposure for people living in coastal areas to airborne toxins."
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