Study links ecosystem changes in temperate lakes to clima...(lpine and temperate ecozones in North Am...)

Date:12/22/2008

lpine and temperate ecozones in North America and western Europe. Aquatic ecosystem changes across the circumpolar Arctic were found to occur in the late-19th and early 20th centuries. These were similar to shifts in algal communities, indicating decreased ice cover and related changes, over the last few decades in the temperate lakes.

"As expected, these changes occurred earlier by about 100 years in highly sensitive Arctic lakes, compared with temperate regions," says Dr. Smol, recipient of the 2004 Herzberg Gold Medal as Canada's top scientist.

In a detailed study from Whitefish Bay, Lake of the Woods, located in northwestern Ontario, strong relationships were found between changes in the lake algae and long-term changes in air temperature and ice-out records. The authors believe that, although the study was focused on algae preserved in lake sediments, changes to other parts of the aquatic ecosystem are also likely (for example algal blooms and deep-water oxygen levels).

"The widespread occurrence of these trends is particularly troubling as they suggest that climatically-induced ecological thresholds have already been crossed, even with temperature increases that are below projected future warming scenarios for these regions," adds Dr. Paterson. The authors warn that if the rate and magnitude of temperature increases continue, it is likely that new ecological thresholds will be surpassed, many of which may be unexpected.

"We are entering unchartered territory, the effects of which can cascade throughout the entire ecosystem," concludes Dr. Smol.

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Contact: Nancy Dorrance nancy.dorrance@queensu.ca Queen's University Source:Eurekalert

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