Passive carbon electrodes above and below the fish monitor bioelectrical currents and digitally convert them into data for real-time monitoring. Here, one of eight bluegills at work in an aquatic biomonitor chamber. (Photo courtesy of U.S. Army Medical Research and Materiel Command.)
By David E. Trader
One Army-developed technology relies on nothing more than nature to help ensure that a daily and vital substance is safe and readily available. The aquatic biomonitor, available commercially as the Intelligent Aquatic Biomonitor System (iABS), uses fish and their breathing patterns to detect the presence of potentially toxic substances in water. The iABS employs a team of eight bluegill (Lepomis macrochirus), also known as sunfish or bream, to provide 24/7 monitoring of water supplies.
The U.S. Army Center for Environmental Health Research (USACEHR) is tasked with developing biomonitoring technologies for the many environmental health hazards that military members face on a day-to-day basis. The information collected by USACEHR allows the organization to provide diagnostic and prognostic tools to the military for environmental and occupational health surveillance.
“Fish are one of the greatest model systems for the detection of contaminants in water,” said Tommy Shedd, a Research Biologist who worked on the iABS. “When you think of the potential for human chemical exposure from water, what better indicator of the potential hazard than a living organism like the fish? The fish are a first line of defense as a broadband detector of potential harmful chemical hazards in water because of their integrated rapid response to abnormal contaminants in the water. The fish do not tell you what the problem is, just that there is a water problem that you should investigate further.”
The eight fish are deployed for a three-week tour of duty, while eight others wait on standby to be rotated in. The fish are placed into individual “stalls” separated by a frosted glass pane. Carbon block electrodes are suspended above and below each fish, capturing the electrical signals generated by the muscles in the fish as they breathe (similar to heart-rate patterns on an electrocardiogram). The device monitors ventilation rate, average depth of signal, cough rate, and percent movement, as well as water quality parameters including water pH, temperature, conductivity, and dissolved oxygen, which are known to affect the way a fish breathes. To protect these eight worker fish, the device is designed to withstand any nontoxic events, such as power or water flow failure.
All of the collected data are then converted to electrical signals, which are amplified, filtered, and transmitted to a laptop computer where they can be analyzed for changes in the environment. If six of the eight fish start behaving abnormally, the device sends out an alert and begins an automated sampling process to screen the water for toxins. If a toxic threat is determined to be present, personnel are called in to mitigate it.
Laboratory tests have shown that the iABS responds within an hour to most chemicals at acutely toxic levels. Within a few hours, the iABS can produce real-time monitoring. Furthermore, the electronic components used in the device are relatively low-cost, and the automated biomonitor alerts personnel only as needed, so continuous observation is unnecessary.
This combination of science and nature was transitioned to commercial development by a team of USACEHR scientists, supported by an Army Science and Technology Objective. The Environmental Sentinel Biomonitor Team was lead by USACEHR Science and Technology Director Dr. William van der Schalie and a team of researchers and biologists. In December 2004, the iABS was awarded an Army Research and Development Award, and in June of 2010 van der Schalie and the team were finalists for the Service to America Medal as a result of their work in aquatic biomonitoring.
The iABS is being used in several large municipalities across the United States to monitor water supplies. The eight small fish thus could save millions of people from using contaminated water sources. In one large city, the bluegills detected a diesel fuel spill in the water source before it reached the water supply. The USACEHR is also looking into other potential tools using the same type of technology. One technology uses cell monolayers to detect toxicity; changes in electrical resistance across the cell layer signal a change in the environment. This allows for a smaller and more transportable device that could be used in the field or in combat to ensure that water is safe and free of contaminants.
- DAVID E. TRADER is a Research Biologist at USACEHR. He holds a B.A. in biology from McDaniel College (formerly Western Maryland College) and an M.S. in environmental biology from Hood College. Trader is the Institutional Animal Care and Use Committee Chairman for USACEHR and a member of the American Water Works Association and the Society for Environmental Toxicology and Chemistry.