North America's northernmost lake affected by global warming

Analyses conducted by researchers from Université Laval’s Center for Northern Studies reveal that the continent’s northernmost lake is affected by climate change. In an article to be published in the September 28 edition of Geophysical Research Letters, the international research team led by Université Laval scientists Warwick Vincent and Reinhard Pienitz reports that aquatic life in Ward Hunt Lake, a body of water located on a small island north of Ellesmere Island in the Canadian Arctic, has undergone major transformations within the last two centuries.

The speed and range of these transformations—unprecedented in the lake’s last 8,000 years—suggest that climate change related to human activity could be at the source of this phenomenon.

The researchers’ conclusions are based on the analysis of a sediment core extracted in the center of Ward Hunt Lake in August 2003. This 18 centimeter long sediment core containing algae pigments and diatom remnants was used by the researchers as a biological archive in order to determine the diversity and abundance of aquatic life-forms in the lake over the last 8,450 years.

Analysis of the deepest layers of sediment revealed a very small number of algae as well as only minor variations in concentration. However, the top two centimeters of the core, which correspond to the last 200 years, showed abrupt changes in the lake’s algae population: during that period, chlorophyll a concentration, a pigment found in every species in the lake, increased by a factor of 500. A type of diatom typical of very cold environments also made its first appearance during the same period. “The absence of diatoms and the low pigment concentration below the top 2.5 centimeters of the core suggest that the lake was permanently frozen in the past,” explains lead author and Center for Northern Studies researcher Dermot Antoniades.

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. The lake itself is permanently covered by a 4-meter layer of ice, except for a small peripheral zone that thaws out during a few weeks every summer. “This is of course an extreme environment for living organisms, but our data indicate that current conditions make the lake a more favorable location for algae growth than it was in the past,” points out Antoniades. “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,” concludes the researcher.

In addition to Antoniades, Vincent, and Pienitz, the article is co-authored by Catherine Crawley from the University of Toronto, Marianne Douglas from the University of Alberta, Dale Andersen from the Center for the Study of Life in the Universe (USA), Peter Doran at the University of Illinois in Chicago (USA), Ian Hawes from the National Institute of Water and Atmospheric Research (New Zealand), and Wayne Pollard from McGill University.

This study was conducted as part of the ArcticNet program, which brings together scientists and managers in the natural, human health and social sciences with their partners in Inuit organizations, northern communities, federal and provincial agencies and the private sector to study the impacts of climate change in the coastal Canadian Arctic.

Source: Université Laval

Related stories:

Researchers view microorganisms from space
What is the smallest thing you can see from space? From a standard shuttle orbit of 217 kilometers above the Earth’s surface, it is suggested that you can see the Great Wall of China. With the aid of binoculars, you can also see clearly the pyramids of Giza, large ships and even major roads.
Warming Could Radically Change Lake Tahoe in 10 Years
A new UC Davis study predicts that climate change will irreversibly alter water circulation in Lake Tahoe, radically changing the conditions for plants and fish in the lake -- and it could happen in 10 years.
Study of bacterial communities may provide climate-change clues
As part of the world carbon cycle, bacterial communities in freshwater lakes break down carbon in decaying organic matter, converting it into carbon dioxide that is released into the atmosphere.
More nutritious, less toxic high-quality food helps reduce toxins in the food chain
Research led by Dartmouth scientists found that animals fed nutritious, high-quality food end up with much lower concentrations of toxic methylmercury in their tissues. The result suggests ways in which methylmercury—a neurotoxin that can accumulate to hazardous levels—can be slowed in its passage up the food chain to fish.
Researchers to study why dead zone returned to Lake Erie
A $2.5 million grant will fund a 5-year study examining why dead zones have returned to Lake Erie, and researchers hope the findings will allow them to detect the cause and stop the spread before the fishery and tourism industries suffer.
Lake Tahoe Clarity Holds Steady in 2005
The waters of Lake Tahoe were clear to an average depth of 72.4 feet in 2005, according to UC Davis scientists who have monitored the lake since 1968. That keeps the clarity measurement in the range where it has been for the past five years -- and where it was for other multiyear periods in the 1990s.


Satellites Spot Mighty Mississippi – In The Atlantic
Scientists using satellite imagery found that at least 23 percent of the water released from the mouth of the Mississippi River from July through September 2004 traveled quite a distance - into the Gulf of Mexico, around the Florida Keys, and into the Atlantic Ocean.
Lake Tahoe Clarity Improved Slightly in 2004
The waters of Lake Tahoe were clear to an average depth of 73.6 feet in 2004, according to UC Davis scientists who have monitored the lake since 1968. That is a slight improvement from 2003, when the lake's waters were clear to 71 feet.

News discussion:

Space & Earth science news