Measurements of American lobster heart rate and movements in the wild using a low-cost open source datalogger

Abstract

To better understand the behavior of the American lobster (Homarus americanus) in the wild, we developed the C-HAT (Crustacean Heart and Activity Tracker): a datalogger capable of continuously recording the triaxial acceleration, compass heading, and heart rate of lobsters that are freely moving in their natural habitat. C-HATs and acoustic transmitters were affixed to six lobsters that were released within an acoustic positioning array off the coast of New Hampshire (USA) and recaptured by divers after 15–47 h at large. Lobster heart rates tended to be ~ 60 beats per minute (bpm) at rest, but increased to ~ 80 bpm during periods of activity. The presence of brief cardiac startle responses during the beginning of some periods of activity suggested that at least a third of their movement bouts occurred in response to external stimuli, such as interactions with other species. The combination of acoustic positioning data and datalogging allowed us to determine if various indices of acceleration could be used to estimate distance traveled. We found a significant correlation between a Movement Index (MI), based on differentiation of the three axes of acceleration, and the distance lobsters traveled in 10 min based on telemetry data. This enabled us to use the MI in concert with compass headings to reconstruct lobster movement paths via dead reckoning. This study demonstrates the potential for low-cost, open-source, dataloggers to provide detailed information on the daily behavior and physiology of marine invertebrates in the wild.