for National Geographic News
The common bluegill fish is being used to protect public drinking water for millions in the United States from terrorists and accidental contamination.
An automated machine developed by the U.S. Army uses bluegills—a hardy species about the size of a human hand—to continuously monitor water quality in New York City; San Francisco, California; and Washington, D.C.
Unlike current humanmade sensors, bluegills can respond to a wide range of chemicals and provide rapid detection of developing toxic water conditions.
The Army system, for example, can quickly detect toxic materials such as cyanide, organic solvents, and pesticides.
(Related: "Loons Sound Alarm on Mercury Contamination" [May 2003].)
"It's definitely gone well beyond the 'canary in the coal mine' aspect," said Tom Shedd, a biologist with the U.S. Army Center for Environmental Health Research in Fort Detrick, Maryland, who co-invented the system. Miners once used the health of canaries to monitor for the presence of deadly methane gas.
"It's a high-tech technology that has been brought to this new millennium because of advanced hardware and software capabilities."
Since the terrorist attacks of September 11, 2001, federal law has required nearly all communities to assess the vulnerability of their water systems to terrorism or other intentional acts that would disrupt delivery of safe and reliable drinking water.
The Army started development of its early-warning system—now sold under the commercial name 1090 Intelligent Aquatic BioMonitoring System—about six years ago, Shedd says.
The system works by monitoring the behavior of eight bluegills that swim freely in tanks where dechlorinated water flows at reservoirs or treatment plants.
Electrodes mounted in the aquarium monitor the fishes' respiratory behavior.
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