EFFECTS OF PRESSURE AND TEMPERATURE ON THE EKG AND HEART RATE OF THE HYDROTHERMAL VENT CRABBYTHOGRAEA THERMYDRON(BRACHYURA)

Abstract

Effects of pressure and temperature on the electrocardiogram (EKG) and heart rate of crabs from the Galapagos deep-sea (2500 meters) hydrothermal vents were studied. Vent crabs require high hydrostatic pressure for long term survival. During decompression their EKG is disrupted and their heart rate is reduced. Low temperature reduces these decompression effects. The crabs have a higher temperature tolerance while at their environmental pressure (238 atm) and can withstand shortterm exposure to temperatures as high as 37C. Possible mechanisms for the action of pressure on neuromuscular systems are discussed. Habits and physiological capabilities of the crabs in the unusual vent environment are suggested on the basis of their physiological tolerances.

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

“…Within these chambers, water is recirculated from an open external source and so chemical parameters within the system can be maintained and monitored. Such technological progress was crucial in developing the capacity to maintain organisms at controlled hydrostatic pressure for extended periods of time [6,7,14].…”

“…Cardiac activity was used in many of these experiments as a continual indicator of respiratory functioning [6,7]. In Crustacea, this was achieved by implanting silver wires directly into either side of the heart [15].…”

“…In Crustacea, this was achieved by implanting silver wires directly into either side of the heart [15]. Although some small organisms remained highly sensitive to the procedure [16,17], it was experimentally proven not to dramatically affect short-term stress response in the hydrothermal vent crab, Bythograea thermydon [6]. Nonetheless, this invasive method required drilling through the carapace and penetration of the pericardial sinus when attaching the sensor [18].…”

“…Thus, cardiac activity (as a proxy of respiratory capacity) can be employed as a sensitive indicator of physiological impairment [29]. Indicatively in Crustacea, changes in cardiac activity have already been observed in response to hydrostatic pressure [6,7] as well as hormone concentrations [30], mode and extent of activity [31], threat of predation [23], emersion from water [32], temperature [33] and environmental contaminants, such as copper [34].…”

“…Developing methods for continuously monitoring the physiological state of an organism under controlled pressures was therefore integral to gain *Corresponding author. Email: nr105@soton.ac.uk a more comprehensive understanding of the susceptibility and resilience of marine organisms to variations in depth [6,7]. When considered in conjunction with phylogenetic evidence, such methods can even help to explain the distribution of extant aquatic species with respect to depth, and how this may have changed over evolutionary time [3].…”