Friday, April 29, 2011

An early warning sign for ecosystem collapse?

Jennifer Carpenter in Science: … now a team of ecologists has shown that it is possible to detect early distress signals in a lake that foretell a major disruption to its ecology. If researchers could identify similar signals in other ecosystems, they might one day predict, and perhaps even prevent, ecological meltdowns.

The collapse of the Atlantic cod fishery in the early 1990s saw the most abundant fish in the North Atlantic disappear due to overfishing. Such events are becoming increasingly common as humans overfish, overgraze, and alter the climate. Connections between predators and prey—often described as a food web—become destabilized. This leaves ecosystems vulnerable to dramatic changes, such as when a single species, like certain algae, grows out of control and forms toxic blooms, like the red tides common off the coast of Florida and Mexico. In theory, learning to detect the precursors of environmental distress could help raise the alarm before any damage is irreversible. But while that's a nice idea on paper, no one has shown that it is possible in real ecosystems.

Now, in the first study of its kind, researchers have pinpointed early warning signs for the disruption of a food web in a lake. By gradually introducing a large fish species—the largemouth bass—into a Wisconsin lake dominated by smaller algae-eating fish, a team of ecologists pushed the aquatic ecosystem to a critical limit where the largemouth bass came to dominate the food web….

Right state, wrong lake--Little Cedar Lake in Wisconsin, shot by Leehall7

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