Heartbeat sensors under pressure: a new method for assessing hyperbaric physiology

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Description/Abstract

Non-invasive heartbeat sensors to measure the cardiac activity of crustaceans have been adapted for use under hyperbaric conditions. Able to record data continuously over long timescales, these sensors can collect high-resolution data on the physiological state of an organism, up to a tested limit of 300 atm. Using this technique, heart rate was recorded in a juvenile of the sublittoral spider crab, Maja brachydactyla (Decapoda: Majidae), when subjected to hydrostatic pressures of 1, 50, 100, and 150 atm for periods of 30 minutes. Heart rate increases with pressure until 100 atm (One-way repeated measures ANOVA: F (4, 25) = 154.76, p < 0.001). However, the significant decrease in the mean heart rate from 137.07 bpm at 100 atm to 118.40 bpm at 150 atm (t-test: t = 4.581, d.f. = 10, p < 0.001) indicates a mechanistic limit in the cardiac response of this species to pressures beyond 100 atm. This method could be potentially applied to any marine invertebrate with a neurogenic heart.