Protocol for Field Monitoring of Cardiac Activity in Intertidal Mussels Using the Pulse Device

This protocol describes a standardized field method for non-invasive recording of cardiac activity in intertidal mussels using the field-PULSE infrared sensor during low-tide emersion. It covers mussel selection criteria, sensor placement based on the internal anatomy of mussel, signal stabilization, recording procedure, metadata collection via the Pulse App (v3.7), and data management. The protocol is designed to ensure reproducibility across operators, sites, and latitudinal sampling campaigns.