Real-time automated behavioural monitoring of mussels during contaminant exposures using an improved microcontroller-based device.

An improved microcontroller-based device for real-time biomonitoring of mussel behaviour is introduced in this study. Open source Arduino platforms were used as processing cores and infra-red (IR) sensors (with transistor output) and Hall sensors to record the cardiac activities and valve movements of mussels. Compared to the devices described in previous studies, this device has low cost, high throughput, and high portability, and can be applied to conduct real-time preliminary automatic data processing. Mediterranean mussels were exposed to Cu2+ and microplastics and their cardiac activities and valve movements were recorded. The results demonstrated that Cu2+ exposure caused valve closure and a drop in the heart rate, similar to the behaviour during natural periods of bradycardia in mussels. The microplastic exposures tended to cause high oscillations (low concentration of microplastics) and slow decreases (high concentration of microplastics) of the maximum valve open positions. Such oscillations and decreases appeared to reset and restart after the bradycardia period. The device has potential to measure and establish behavioural responses of mussels and other bivalves, to the stress of exposure from environmental contaminants.