Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Tale of Two Lakes: One Gives Early Warning Signal for Ecosystem Collapse

29.04.2011
First experimental evidence that radical ecosystem change can be detected in advance

Researchers eavesdropping on complex signals from a remote Wisconsin lake have detected what they say is an unmistakable warning--a death knell--of the impending collapse of the lake's aquatic ecosystem.

The finding, reported today in the journal Science by a team of researchers led by Stephen Carpenter, an ecologist at the University of Wisconsin-Madison (UW-Madison), is the first experimental evidence that radical change in an ecosystem can be detected in advance, possibly in time to prevent ecological catastrophe.

"For a long time, ecologists thought these changes couldn't be predicted," says Carpenter. "But we've now shown that they can be foreseen. The early warning is clear. It is a strong signal."

The implications of the National Science Foundation (NSF)-supported study are big, says Carpenter.

"This research shows that, with careful monitoring, we can foresee shifts in the structure of ecosystems despite their complexity," agrees Alan Tessier, program director in NSF's Division of Environmental Biology. "The results point the way for ecosystem management to become a predictive science."

The findings suggest that, with the right kind of monitoring, it may be possible to track the vital signs of any ecosystem and intervene in time to prevent what is often irreversible damage to the environment.

"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."

"Networks for long-term ecological observation, such as the [NSF] Long-Term Ecological Research network, increase the possibility of detecting early warnings through comparisons across sites and among regions," the scientists write in their paper.

Ecosystems often change in radical ways. Lakes, forests, rangelands, coral reefs and many other ecosystems are often transformed by overfishing, insect pests, chemical changes in the environment, overgrazing and shifting climate.

For humans, ecosystem change can impact economies and livelihoods such as when forests succumb to an insect pest, rangelands to overgrazing, or fisheries to overexploitation.

A vivid example of a collapsed resource is the Atlantic cod fishery.

Once the most abundant and sought-after fish in the North Atlantic, cod stocks collapsed in the 1990s due to overfishing, causing widespread economic hardship in New England and Canada. Now, the ability to detect when an ecosystem is approaching the tipping point could help prevent such calamities.

In the new study, the Wisconsin researchers, collaborating with scientists at the Cary Institute for Ecosystem Studies in Millbrook, N.Y., the University of Virginia in Charlottesville and St. Norbert College in De Pere, Wis., focused their attention on Peter and Paul Lakes, two isolated and undeveloped lakes in northern Wisconsin.

Peter is a six-acre lake whose biota were manipulated for the study and nearby Paul served as a control.

The group led by Carpenter experimentally manipulated Peter Lake over a three-year period by gradually adding predatory largemouth bass to the lake, which was previously dominated by small fish that consumed water fleas, a type of zooplankton.

The purpose, Carpenter notes, was to destabilize the lake's food web to the point where it would become an ecosystem dominated by large predators.

In the process, the researchers expected to see a relatively rapid cascading change in the lake's biological community, one that would affect all its plants and animals in significant ways.

"We start adding these big ferocious fish and almost immediately this instills fear in the other fish," Carpenter says.

"The small fish begin to sense there is trouble and they stop going into the open water and instead hang around the shore and structures, things like sunken logs. They become risk-averse."

The biological upshot, says Carpenter, is that the lake became "water flea heaven."

The system becomes one where the phytoplankton, the preferred food of the lake's water fleas, is highly variable.

"The phytoplankton get hammered and at some point the system snap into a new mode," says Carpenter.

Throughout the lake's three-year manipulation, all its chemical, biological and physical vital signs were continuously monitored to track even the smallest changes that would announce what ecologists call a "regime shift," where an ecosystem undergoes radical and rapid change from one type to another.

It was in these massive sets of data that Carpenter and his colleagues were able to detect the signals of the ecosystem's impending collapse.

Ecologists first discovered similar signals in computer simulations of spruce budworm outbreaks.

Every few decades the insect's populations explode, causing widespread deforestation in boreal forests in Canada. Computer models of a virtual outbreak, however, seemed to undergo odd blips just before the outbreak.

The problem was solved by William "Buz" Brock, a UW-Madison economist who for decades has worked on the mathematical connections of economics and ecology.

Brock utilized a branch of applied mathematics known as bifurcation theory to show that the odd behavior was in fact an early warning of catastrophic change.

In short, he devised a way to sense the transformation of an ecosystem by detecting subtle changes in the system's natural patterns of variability.

The upshot of the Peter Lake field experiment, says Carpenter, is a validated statistical early warning system for ecosystem collapse.

The catch, however, is that for the early warning system to work, intense and continuous monitoring of an ecosystem's chemistry, physical properties and biota are required.

Such an approach may not be practical for every threatened ecosystem, says Carpenter, but he also cites the price of doing nothing.

"These regime shifts tend to be hard to reverse. It is like a runaway train once it gets going and the costs--both ecological and economic--are high."

In addition to Carpenter and Brock, authors of the Science paper include Jonathan Cole of the Cary Institute of Ecosystem Studies; Michael Pace, James Coloso and David Seekell of the University of Virginia at Charlottesville; James Hodgson of St. Norbert College; and Ryan Batt, Tim Cline, James Kitchell, Laura Smith and Brian Weidel of UW-Madison.

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Terry Devitt, University of Wisconsin-Madison (608) 262-8282 trdevitt@wisc.edu
Related Websites
NSF Long-Term Ecological Research Program: http://www.lternet.edu
NSF LTER North Temperate Lakes Site: http://www.lternet.edu/sites/ntl/

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2010, its budget is about $6.9 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives over 45,000 competitive requests for funding, and makes over 11,500 new funding awards. NSF also awards over $400 million in professional and service contracts yearly.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Ecology, The Environment and Conservation:

nachricht Global threat to primates concerns us all
19.01.2017 | Deutsches Primatenzentrum GmbH - Leibniz-Institut für Primatenforschung

nachricht Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>