"Warming linked to 'unprecedented' algae growth in Arctic lake"

MONTREAL (AFP) — Global warming is believed to be softening the harsh Arctic environment, causing the algae population in Canada's northernmost lake to spike over the past two centuries, researchers said Wednesday.

The team, led by Laval University scientists Warwick Vincent and Reinhard Pienitz, found aquatic life in Ward Hunt Lake, located on island north of Ellesmere Island, increased 500-fold during the period.

The changes occurred at a speed and range "unprecedented in the lake's last 8,000 years," the researchers said in a statement.

And, they say, the likely culprit is "climate change related to human activity."

The findings, to appear in the journal Geophysical Research Letters on September 28, are based on an analysis of an 18-centimeter (seven-inch) sediment core plucked from the lake's center in August 2003.

Its layers, the researchers said, chronicle the diversity and abundance of aquatic life in the lake over the last 8,450 years.

The deepest layers of sediment revealed a very small number of algae as well as only minor variations in concentration, but the top two centimeters (0.8 inches), corresponding to the last 200 years, showed an abrupt increase in the lake's algae population, they said.

"This is of course an extreme environment for living organisms," said lead author Dermot Antoniades of the Center for Northern Studies.

"But our data indicate that current conditions make the lake a more favorable location for algae growth than it was in the past."

"We cannot claim with certainty that these changes were brought on by human activity, but natural variations observed over the last millennia were never so abrupt and extensive," he said.

Located on the 83rd parallel in the Quttinirpaaq (meaning "top of the world" in Inuktitut) National Park, Ward Hunt Island is completely surrounded by ice.