Mussels detect contamination by a sensor on their shells

American researchers attached small, inexpensive mussel sensors to measure how open their shells were. This allows them, for example, to detect pollution in water at an early stage.

Mussels eat plankton that they filter from the water by opening their shells slightly. But if a harmful substance appears, the entire mussel bottom shuts the valves at the same time, which is a form of self-protection.

This mechanism was known for a long time, but scientists recently realized that it could be used to measure environmental pollution, for example. However, finding a practical way to track underwater mussels, without hindering this, was still an art. Often the measurement was very inaccurate or just practical for laboratory procedure.

Fitbit mussels

Researchers at North Carolina State University (USA) have developed small, inexpensive, waterproof motion sensors and installed them on mussels, one at the top of the shell and the other at the bottom. “We have developed a ‘Fitbit’ dedicated to mussels to ‘track their activity,’” lead researcher Alper Bozkurt, professor of electrical and computer engineering, said in a press release from NCSU. “We have developed a ‘Fitbit’ dedicated to mussels to ‘track their activity,’” a Fitbit watch is a watch that monitors the wearer’s activity.

The sensor is called Inertial measurement units (IMUs), similar to the sensor in your smartphone that detects motion. The IMU consists of a magnetometer to measure direction and an accelerometer to measure acceleration. The latter can be used for measurement when the mussel has suddenly closed its shell. By combining accelerometers in different directions, the researchers were also able to measure how open the cortex is, with an accuracy of less than a millimeter. The magnetometer was a control measure.

Monitor the environment

The researchers tested the system in an aquarium of four mussels. The sensors are connected to a weatherproof base station that collects data with flexible cables. The sensors lasted for 250 hours and did not appear to interfere with the mussels. To be on the safe side, scholars write in their article in their journals IEEE Sensors Messages: “Invertebrates are exempt from animal welfare regulations.”

When used in practice – even outside the laboratory – the base station can be powered by solar panels. In principle, the system is suitable for monitoring dozens of mussels at the same time.

Canary

The researchers expect the system to be suitable for monitoring the environment. “Think of the canary in the coal mine,” said co-researcher Jay Levine in the press release. Only we can detect the toxin without the mussels being dying. However, we can investigate how environmental factors affect the health of the mussels.

Study the behavior of mussels

So researchers believe their sensors are suitable for discovering more about mollusks. “Our goal is to create a ‘mussel internet’ and monitor their individual and group behavior,” says Boscourt.

Levine adds: “ In addition to validating its effectiveness as an environmental monitor, we are optimistic that the technology could help us learn new things about the mussels themselves. What prompts them to filter and eat? Does their behavior change in response to temperature changes? Thanks to the sensors, we can measure the standard behavior of individual animals and monitor the movement of their shells in response to changes in the environment.

The next step is for researchers to test their system in nature under real conditions. More details about measuring mussels can be read in a press release from North Carolina State University.

Text: Bastian Wentzl
Photos: NCSU

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