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Why Lake Ontario Turned Neon Blue Last Week

Science & Tech  (tags: cyanobacteria, Lake Ontario, study, science, environment, interesting, research, space, nasa )

- 1753 days ago -
If you flew over the Great Lakes last week -- either in an airplane or aboard the International Space Station -- you might have noticed an explosion of colour between Ontario and New York state.

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Michael O (176)
Tuesday September 3, 2013, 8:32 pm
Lake Ontario was an electric blue on all but its westernmost surface.

The phenomenon was visible from orbit, where an astronaut on the space station captured it with a camera.

A NASA satellite also recorded images.

The lively neon hue used to be a common event on Lake Ontario, but has grown rarer over the last two decades, said biologist Michael Twiss, a professor at Clarkson University in New York state who studies the Great Lakes.

Twiss explained that the colour develops from blue-green algae, which thrive in warm temperatures. They cause the water's pH to rise, which in turn makes calcium and carbonate ions that are naturally present in the water condense into white blocks of calcite on the surface of the algae.

Those tiny white chunks reflect blue and green light especially well, Twiss said, giving the water its vibrant aquamarine tint.

The phenomenon is called a "whiting event."

"It's odd for it to happen in Lake Ontario. It used to happen all the time," he said. But then invasive zebra mussels swept into the Great Lakes in the early 1990s. "They started accumulating the calcium in their shells. So now this only tends to happen when it's warm, because calcite precipitates even more when it's warm."

Eventually, the colouring from the whiting event fades as the water cools and as the condensing chunks of calcite get large enough to sink the tiny plankton.

Twiss said the proliferation of cyanobacteria is not to be confused with a harmful algal bloom, where algae multiply and produce a toxin that can make the water unsafe for swimming or drinking.

It's very difficult to distinguish a harmful bloom using satellite images alone, but in this case, available evidence suggests the cyanobacteria are not part of one, said Greg Boyer, a chemistry professor at the State University of New York and director of the Great Lakes Research Consortium.

"It so happened we had an Environment Canada ship doing a survey of Lake Ontario during Aug. 19-24 same time as the [NASA] satellite," he said in an email. "What few algae were there were dominated by dinoflagellates, diatoms and other generally beneficial algae.... There is no ground-truth data that would support the presence of a bloom and lots of contradictory data that says a bloom did not occur."

Such blooms occur often enough on Lake Erie. Scientists even warned earlier this year that Lake Erie was in for "very bad algae" this summer.

The predictions were right: by mid-July, the public health department in Chatham-Kent, Ont., had to close all but one of the region's public beaches due to the bacteria.

Nancy Anderson (21)
Tuesday September 3, 2013, 9:41 pm
Pretty color from space.

Past Member (0)
Wednesday September 4, 2013, 12:34 am
Beautiful color---must be something to have see it from space! And yet Toronto's beaches are some of the cleanest beaches 4 the last 10-15 years...thanks Michael

DaleLovesOttawa O (198)
Wednesday September 4, 2013, 8:27 am
Fascinating article and colour.

Jim Phillips (3257)
Wednesday September 4, 2013, 9:00 am
Awesome and fascinating.

Ty, Michael.

. (0)
Wednesday September 4, 2013, 9:01 am
Yeah, and the week before that it was a dirty milky white. Explain that one.

Dot A (182)
Wednesday September 4, 2013, 10:04 am
Wouldn't have been aware of this recent occurance, but for this post!,.... Thanks, Michael! Like others have said, the color is quite beautiful~

Kit B (276)
Wednesday September 4, 2013, 12:31 pm

This a little confusing, the Great Lakes are not often thought of as warm water. Though the answer for the phenomena is within a warming trend. Ummmm!

S S (0)
Wednesday September 4, 2013, 12:40 pm
Thank you.

Nelson Baker (0)
Wednesday September 4, 2013, 2:05 pm

Nancy M (169)
Wednesday September 4, 2013, 2:26 pm
And Upstate will get tons of snow and the right-wing will say there is no Global Warming. In fact, it is when the lakes are TOO WARM and never freeze over that there is more snow in Upstate.

Vicki M (28)
Wednesday September 4, 2013, 4:04 pm
N&Shared very interesting!

Roger G (154)
Wednesday September 4, 2013, 5:40 pm
noted, thanks

Past Member (0)
Thursday September 5, 2013, 6:16 am

Past Member (0)
Thursday September 5, 2013, 6:38 am
never knew. thanks

Lona G (79)
Thursday September 5, 2013, 7:38 am
Great article. I'n glad to hear that the blue colouring was not due to the toxic blue algae we've had to deal with here in our swimming waters when the temperatures suddenly shot up and out of control .

Jamie Clemons (282)
Thursday September 5, 2013, 11:45 am
Glad it is nothing harmful.

Robert Hardy (68)
Thursday September 5, 2013, 11:12 pm
How the would changes before our very eyes.

Past Member (0)
Friday September 6, 2013, 3:59 am

Kerrie G (116)
Friday September 6, 2013, 4:14 am
Noted, thanks.

Melania Padilla (122)
Monday September 9, 2013, 1:34 pm
Blue-green algae are beautiful under the microscope. Algae are so interesting!

Sonia M (60)
Tuesday September 10, 2013, 10:09 am
Great article with amazing pictures..Thanks for sharing

Bob P (394)
Tuesday September 10, 2013, 4:42 pm
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