Lake Ontario can breathe easy: Likely no algae bloom

The greenish colour viewed from NASA's Aqua satellite is likely caused by an inorganic process called "whiting" rather than a dangerous algae bloom. NASA/Aqua/MODIS

UPDATE: NASA Earth Observatory has since updated their story. To read it, click here.

TORONTO – A NASA claim that an astronaut and a weather satellite captured a massive algae bloom in Lake Ontario from space is being refuted by researchers.

Jim Watkins, a post doctoral researcher at Cornell University in New York believes that, instead, the bluish-green colouring of the lake is being caused by a process called “calcium whiting.”

Watkins is the principal author of a paper published this month in the Journal of Great Lakes Research on the subject of whiting.

Concerns about the claim of a plankton bloom in Lake Ontario were first presented to Global News by David Bird, a professor of biological sciences at L’Université du Québec à Montréal (UQAM). He said that it is an easy mistake to make using satellite photos.

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“You could figure it out if you worked on it, but just by eye, there’s no way to tell.”

However, he added that it would be unlikely that cyanobacteria – the blue-green algae – was entirely responsible for the coloured appearance of the lake because if it were, it would be a “major environmental event.”

Watkins agreed.

“Whiting is a common late summer phenomenon in Lake Ontario, where calcium carbonate precipitates out in the surface of the water column,” Watkins told Global News. “The lake is in a limestone basin so high in… calcium. Also carbonate is less soluble in warmer water (hence the late summer timing).”

The ideal recipe for a whiting seems to be an increase of phytoplankton – single-cell plants, such as algae, that convert sunlight, carbon dioxide and nutrients into food sources in water as well as warmer water, such as that which occurs at the end of summer.

“Sometimes you have a cool year or maybe not a so productive year, and those two things seemed to be linked pretty well to years that you don’t get this event,” Watkins said.

Watkins was out on Lake Ontario on Aug. 12 and 13 with the United States Environmental Protection Agency.

“We identified a likely whiting event that matches the satellite imagery through measurements of high turbidity [the stirring up of particles],” he said.
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After being out on the lake, Watkins said that the plankton isn’t a bloom. In fact, chlorophyll concentrations – which are evident in large algae blooms – in Lake Ontario are lower by a factor of 10 compared to Lake Erie where there is a definite algae bloom.

As for concerns as to how this affects our water, Watkins said, “I wouldn’t call it a bad thing… One positive thing is that it gets a lot of stuff down to the bottom of the lake. It transports things back to the bottom, and that’s kind of an interesting twist.”

Though Watkins believes that a whiting is the likely cause, he added, “One thing lacking, though, is the actual measurement of calcium carbonate in the water to confirm.”

Though we may notice a change in colour to our water, Watkins said, it isn’t harmful to us.

A similar process that occurred in Lake Michigan was witnessed from space in 1999 and 2001 by NASA’s SeaWiFs Project.

Lake Michigan “whiting” as observed in 2001. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

Watkins noted that the sediment record in the Great Lakes shows that whiting events didn’t occur until the 1930s, likely due to increased phosphorus being put into the water. If we reduce phosphorus – as the International Joint Commission, a collaborative effort by Canada and the United States recommended last week – it would likely end the whitings.

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“Satellite images indicate that Lake Michigan whitings have stopped since 2004,” Watkins added.

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