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Algae, plankton and insects move north

More chlorophyll in Clyde River lakes a sign of global warming

JANE GEORGE

Researchers from the Univ. of Alberta bore down through the ice into a frozen lake near Clyde River. They'll go down to the bottom of the lake and retrieve a core of lake sediments to study what they contain.

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These changes have to do with an increase in the concentrations of chlorophyll, a group of green pigments found in organisms, which use sunlight to make food.

“What’s important about chlorophyll is that it’s an indicator of warming, and production [of chlorophyll] and climate are really intimately linked,” said Neal Michelutti of the University of Alberta.

Neal and his team took sediments from six lakes around Clyde River and then examined these samples to gauge the levels of chlorophyll. They found “dramatic increases” in the concentrations of chlorophyll, starting around the year 1850, when in industrialization started in the South.

“These events appear synchronized with the record of recent climate change,” says the research report, published in the current issue of Geophysical Research Letters.

An increase in chlorophyll means the ice-free growing season is becoming longer and can support more and different forms of aquatic life: algae, plankton and insects.

The results of their analysis can tell much about the impact of climate change.(PHOTOS COURTESY OF NEAL MICHELUTTI)

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“The growing season is very short so a difference of a few weeks on either end makes a huge impact biologically,” Neal said.

However, many of these changes in the lakes are not visible to the eye. The colour of the water won’t change from blue to green, Neal said, but early break-up and later freezing dates are signs the lakes are warming and becoming more productive.

Neal said sediment is a useful tool to get a long-term perspective on what is happening in the climate.

“We can basically collect a lot of sediments, and come back and get them processed and get the results back relatively quickly,” Neal said.

In his study of Clyde River’s lakes, he used an innovative technique called “reflectance spectroscopy.” The new technique allows researchers to “see” in wavelengths what the human eye can’t and to learn about the chemical composition of the sediment.

It’s a technique Neal would like to use in other regions of the Arctic as a way of tracking climate changes.

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