Researchers from NC State University have designed a Fitbit-like sensor system that enables them to monitor freshwater mussels remotely. That same system could also be used to detect toxic elements in aquatic ecosystems based on the mussels’ behavior. Mussels and other mollusks open their shells when feeding and abruptly close when predators or harmful chemicals are present.
“Folks have been trying to find ways to measure how widely mussels or oysters open their shells off and on since the 1950s, but there have been a wide variety of challenges,” states Jay Levine, professor of epidemiology at NC State. “We needed something that allows the animals to move, can be placed in streams and collects data – and now we have it.”
The team developed the monitor using commercially-available components, including a pair of IMUs outfitted with a magnetometer and accelerometer, similar to those found in smartphones. One of the sensors is attached to the mussel’s top shell, while the other is affixed on the bottom, which allows the researchers to tell when the shells open and close. The IMUs are wired to a data acquisition system mounted to a stake placed in the water and are powered by a solar cell. The system transmits the collected data wirelessly via a cellular network.
The current prototype is outfitted with four connected mussels, but the researchers state they could connect dozens more. They also performed more than 250 hours of testing using live mussels in a laboratory tank and found that the sensor system was incredibly accurate, measuring the angle of the mussel’s shell opening to within less than a single degree.