April 29th, 2011 by Joshua S Hill
Researchers who have been manipulating a northern Wisconsin lake have been able to detect a warning signal for the impending collapse of an ecosystem.
The team had been monitoring, Peter Lake in northern Wisconsin, keeping track of all its chemical, biological and physical vital signs so as to track even the smallest changes. Their aim was to find the small change that would announce a regime shift was about to take place; a shift at which point an ecosystem rapidly switches from one type to another.
“For a long time, ecologists thought these changes couldn’t be predicted,” says Stephen Carpenter, a limnologist and professor of zoology at the University of Wisconsin-Madison and one of the world’s foremost ecologists. “But we’ve now shown that they can be foreseen. The early warning is clear. It is a strong signal.”
Such research could lead to the ability to detect, with the right kind of monitoring, the vital signs of a doomed ecosystem and intervene in time to remedy whatever has happened, and reverse the problem.
“With more work, this could revolutionize ecosystem management,” Carpenter says. “The concept has now been validated in a field experiment and the fact that it worked in this lake opens the door to testing it in rangelands, forests and marine ecosystems.”
The researchers introduced predatory largemouth bass into Peter Lake, using nearby Paul Lake as a control, to watch what happened when a predatory fish is introduced into a lake dominated by small fish feeding on water fleas. Their purpose was to destabilize the lake’s food web to a point at which it switched to being dominated by large predators.
“We started adding these big ferocious fish and almost immediately this instils fear in the other fish,” Carpenter explains. “The small fish begin to sense there is trouble and they stop going into the open water and instead hang around the shore and structure, things like sunken logs. They become risk averse.”
The research team collected massive amounts of data from Peter Lake, which allowed them to detect the signal of the ecosystems impending collapse.
Source: University of Wisconsin-Madison
Image Source: Steve Carpenter
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